Change search
Refine search result
3456789 251 - 300 of 531
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 251. Li, Xiaoxin
    et al.
    Gong, Chenghuan
    Gurzadyan, Gagik G.
    Gelin, Maxim F.
    Liu, Jinxuan
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Institute of Artificial Photosynthesis, State Key Laboratory of Fine Chemicals, Dalian University of Technology, 116024 Dalian, China.
    Ultrafast Relaxation Dynamics in Zinc Tetraphenylporphyrin Surface-Mounted Metal Organic Framework2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 1, p. 50-61Article in journal (Refereed)
    Abstract [en]

    Ordered porphyrin-based metal organic frameworks (MOFs) may serve as a model for mimicking the natural photosynthesis with highly ordered chlorophylls, i.e., porphyrin-like chromophores. Study of light harvesting and energy transfer as the primary event of photosynthesis is of great importance leading to improvement of photovoltaics overall performance. Detailed characterization of ultrafast dynamics of zinc tetraphenylporphyrin (ZnTPP) surface mounted metal organic framework (SURMOF) is reported by using various steady-state and time-resolved laser spectroscopic techniques, i.e., time correlated single photon counting, fluorescence up-conversion and transient absorption pump-probe with 20 fs resolution. Obtained results in these nanoporous materials were compared with corresponding results for ZnTPP in ethanol measured under the same conditions. Dramatic quenching of both upper excited singlet state S-2 and first excited state SI was observed. Subpicosecond and picosecond lifetimes were detected in transient fluorescence and absorption. Analytical formulas are derived for the linear absorption, steady-state fluorescence, and fluorescence up-conversion signals. Theoretical description excellently reproduces experimental time and frequency resolved signals. Strong quenching of the femtosecond transients in SURMOF is explained in terms of highly efficient Forster resonance energy transfer between the neighboring porphyrin moieties which is caused by a strong spectral overlap of absorption and steady-state fluorescence spectra and quantum coherent energy transfer and redistribution.

  • 252.
    Li, Xiaoxin
    et al.
    Dalian Univ Technol, State Key Lab Fine Chem, Inst Artificial Photosynth, Dalian 116024, Peoples R China..
    Gurzadyan, Gagik G.
    Dalian Univ Technol, State Key Lab Fine Chem, Inst Artificial Photosynth, Dalian 116024, Peoples R China..
    Gelin, Maxim F.
    Tech Univ Munich, Chem Dept, D-85747 Garching, Germany..
    Domcke, Wolfgang
    Tech Univ Munich, Chem Dept, D-85747 Garching, Germany..
    Gong, Chenghuan
    Dalian Univ Technol, State Key Lab Fine Chem, Inst Artificial Photosynth, Dalian 116024, Peoples R China..
    Liu, Jinxuan
    Dalian Univ Technol, State Key Lab Fine Chem, Inst Artificial Photosynth, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Enhanced S-2 Fluorescence from a Free-Base Tetraphenylporphyrin Surface-Mounted Metal Organic Framework2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 41, p. 23321-23328Article in journal (Refereed)
    Abstract [en]

    The ultrafast transient dynamics of a free-base tetraphenylporphyrin (H2TPP) surface-mounted metal organic framework (SURMOF) is spectroscopically characterized and compared with that of H2TPP in ethanol solution. A dramatic increase of the quantum yield of the Soret band fluorescence (S-2 -> S-0) is observed in the H2TPP-SURMOF, which is accompanied by an increase of the S-2 fluorescence lifetime and a broadening of the fluorescence spectra. In contrast, the Q band (S-1) fluorescence is strongly quenched in the H2TPP SURMOF compared with the fluorescence of H(2)TPPin ethanol solution. The observed transient absorption kinetics supports the fluorescence data. The enhanced fluorescence in the SURMOF compared with H2TPP in solution is attributed to the combination of two factors: the alignment of the vibrational energy levels of the dominant Franck-Condon active mode of the Soret and Q bands and the weaker coupling of these modes to the environment.

  • 253.
    Li, Yuanyuan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Cheng, Ming
    Jungstedt, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Xu, Bo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Optically Transparent Wood Substrate for Perovskite Solar Cells2019In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, no 6, p. 6061-6067Article in journal (Refereed)
    Abstract [en]

    Transparent wood is a candidate for use as an energy-saving building material due to its low density (ca. 1.2 g/cm(3)), high optical transmittance (over 85% at 1 mm thickness), low thermal conductivity (0.23 W m(-1) K-1), and good load-bearing performance with tough failure behavior (no shattering). High optical transmittance also makes transparent wood a candidate for optoelectronic devices. In this work, for the first time, perovskite solar cells processed at low temperature (<150 degrees C) were successfully assembled directly on transparent wood substrates. A power conversion efficiency up to 16.8% was obtained. The technologies demonstrated may pave the way for integration of solar cells with light transmitting wood building structures for energy-saving purposes.

  • 254.
    Li, Zhuofeng
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Soroka, Inna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Min, Fanyi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    pH-Control as a way to fine-tune the Cu/Cu2O ratio in radiation induced synthesis of Cu2O particles2018In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 45, p. 16139-16144Article in journal (Refereed)
    Abstract [en]

    In this work we have optimized the -radiation induced synthesis of Cu-Cu2O particles from aqueous CuSO4 solution by investigating the effect of pH. The obtained precipitate was analyzed by XRD and SEM techniques. The results indicated that at solution pH lower than 3.75, quasi-spherical Cu agglomerates can be formed while at pH higher than 4.40 only octahedron-shaped Cu2O particles are produced. At solution pH in the range from 3.75 to 4.40, a Cu-Cu2O mixture is produced. It was found that the relative amount of Cu2O in the Cu-Cu2O precipitate increases with pH in the studied range. The influence of solution pH on the Cu/Cu2O ratios in the product can be explained on the basis of pH-dependent competition kinetics between the reactions leading to either Cu or Cu2O formation. As a consequence, the composition and morphology of the Cu-Cu2O precipitate can be tuned by controlling pH of the aqueous CuSO4 solution during the -radiation induced synthesis.

  • 255.
    Li, Zhuwei
    et al.
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Hou, Jungang
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Zhang, Bo
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Cao, Shuyan
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Wu, Yunzhen
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Gao, Zhanming
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Nie, Xiaowa
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Two-dimensional Janus heterostructures for superior Z-scheme photocatalytic water splitting2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 59, p. 537-544Article in journal (Refereed)
    Abstract [en]

    Developing robust water splitting photocatalyst remains a pivot challenge for solar-to-fuel conversion. Herein, two-dimensional (2D) Janus bilayer heterostructures are reported by sulfur-vacancy-confined-in ZnIn2S4 (V-s-ZnIn2S4) and WO3 nanosheets as an all-solid-state Z-scheme prototype. First-principle calculations and experimental observations clearly confirm the spontaneous formation of this redox-mediator-free Z-scheme van der Waals heterostructure at atomic level, not only facilitating the space separation of photoexcited carriers with high charge density, enhancing charge dynamics and optimizing charge lifetime, but also accumulating electrons in conduction band of V-s-ZnIn2S4 and holes in valence band of WO3 by internal electric field through W-S bonds. After integrated by NiS quantum dots, novel 2D/2D NiS/V-s-ZnIn2S4/WO3 heterostructures with high stability exhibited an outstanding visible-light hydrogen evolution rate of 11.09 mmol g(-1)h(-1) and an apparent quantum efficiency about 72% at 420 nm, the highest value so far reported among the family of ZnIn(2)S(4 )photocatalysts. This work not only presents novel Janus heterostructures but also paves the atomic-level structural and interfacial design and the construction of 2D Janus bilayer Z-scheme heterojunctions for solar energy conversion applications.

  • 256.
    Liljenberg, Magnus
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Halldin Stenlid, Joakim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Mechanism and regioselectivity of electrophilic aromatic nitration in solution: the validity of the transition state approach2018In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 24, no 1, article id 15Article in journal (Refereed)
    Abstract [en]

    The potential energy surfaces in gas phase and in aqueous solution for the nitration of benzene, chlorobenzene, and phenol have been elucidated with density functional theory at theM06-2X/6-311G(d,p) level combined with the polarizable continuum solvent model (PCM). Three reaction intermediates have been identified along both surfaces: the unoriented pi-complex (I), the oriented reaction complex (II), and the sigma-complex (III). In order to obtain quantitatively reliable results for positional selectivity and for modeling the expulsion of the proton, it is crucial to take solvent effects into consideration. The results are in agreement with Olah's conclusion from over 40 years ago that the transition state leading to (II) is the rate-determining step in activated cases, while it is the one leading to (III) for deactivated cases. The simplified reactivity approach of using the free energy for the formation of (III) as a model of the rate-determining transition state has previously been shown to be very successful for halogenations, but problematic for nitrations. These observations are rationalized with the geometric and energetic resemblance, and lack of resemblance respectively, between (III) and the corresponding rate determining transition state. At this level of theory, neither the sigma-complex (III) nor the reaction complex (II) can be used to accurately model the rate-determining transition state for nitrations.

  • 257. Lin, Tzung-Sheng
    et al.
    Hsieh, Chang-Hsun
    Kuo, Chin
    Juang, Yu-Pu
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Chiang, Hongsen
    Hung, Shang-Cheng
    Jiang, Ching-Chuan
    Liang, Pi-Hui
    Sulfation pattern of chondroitin sulfate in human osteoarthritis cartilages reveals a lower level of chondroitin-4-sulfate2020In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 229, article id 115496Article in journal (Refereed)
    Abstract [en]

    Chondroitin sulfates (CS) account for more than 80% of glycosaminoglycans of articular cartilage, which imparts its physiological functions. We quantified the absolute concentration of the CS components of the full thickness cartilages from the knees of patients with terminal-phase osteoarthritis. Osteochondrol biopsies were removed from the medial femoral condyle and lateral femoral condyle of sixty female patients receiving total knee arthroplasty, aged from 58 to 83 years old. We found that total CS concentrations and chondroitin-4-sulfate disaccharide were significantly lowered in osteoarthritic samples. Microstructure analysis indicated that while chondroitin-0-sulfate was equally distributed across different zones of the osteoarthritic cartilages, chondroitin-4-sulfate is significantly less in the deep zones. Down-regulation of sulfotransferases, the enzymes responsible for CS sulfation in the lesion site of cartilage were observed. Our study suggested chondroitin-4-sulfate down-regulation may be a diagnostic marker for degraded osteoarthritis cartilage, with potential implications in cartilage regeneration.

  • 258. Lindman, Björn
    et al.
    Stilbs, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Molecular diffusion in microemulsions2018In: Microemulsions: Structure and Dynamics, CRC Press, 2018, p. 119-152Chapter in book (Other academic)
    Abstract [en]

    The interest in studies of diffusional processes in microemulsions has grown rapidly during the past few years. The reasons are an increased number of available techniques providing easily interpretable data and the realization that self-diffusion data give unique information on the molecular organization and structure of microemulsions. Furthermore, many current and potential applications of microemulsions are dependent on molecular transport over macroscopic distances.

  • 259.
    Liu, Haiyang
    et al.
    Shenzhen Univ, Coll Optoelect Engn, Key Lab Optoelect Devices & Syst, Minist Educ & Guangdong Prov, Shenzhen 518060, Peoples R China.;Hong Kong Polytech Univ, Dept Appl Biol & Chem Technol, Hong Kong, Hong Kong, Peoples R China..
    Liu, Tianqi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Li, Jia
    Shenzhen Univ, Coll Optoelect Engn, Key Lab Optoelect Devices & Syst, Minist Educ & Guangdong Prov, Shenzhen 518060, Peoples R China..
    Zhang, Youming
    Shenzhen Univ, Coll Optoelect Engn, Key Lab Optoelect Devices & Syst, Minist Educ & Guangdong Prov, Shenzhen 518060, Peoples R China.;Hong Kong Polytech Univ, Dept Appl Biol & Chem Technol, Hong Kong, Hong Kong, Peoples R China..
    Li, Jiahua
    Hong Kong Polytech Univ, Dept Appl Biol & Chem Technol, Hong Kong, Hong Kong, Peoples R China..
    Song, Jun
    Shenzhen Univ, Coll Optoelect Engn, Key Lab Optoelect Devices & Syst, Minist Educ & Guangdong Prov, Shenzhen 518060, Peoples R China..
    Qu, Junle
    Shenzhen Univ, Coll Optoelect Engn, Key Lab Optoelect Devices & Syst, Minist Educ & Guangdong Prov, Shenzhen 518060, Peoples R China..
    Wong, Wai-Yeung
    Shenzhen Univ, Coll Optoelect Engn, Key Lab Optoelect Devices & Syst, Minist Educ & Guangdong Prov, Shenzhen 518060, Peoples R China.;Hong Kong Polytech Univ, Dept Appl Biol & Chem Technol, Hong Kong, Hong Kong, Peoples R China..
    A simple Schiff base as dual-responsive fluorescent sensor for bioimaging recognition of Zn2+ and Al3+ in living cells2018In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 6, no 34, p. 5435-5442Article in journal (Refereed)
    Abstract [en]

    A simple Schiff base fluorescent sensor (BDNOL) was synthesized from the reaction of picolinohydrazide and 4-(diethylamino)salicylaldehyde, and developed for selective detection of Al3+ and Zn2+. This non-fluorescent sensor displayed obvious fluorescence enhancement after binding to Al3+/Zn2+ ions with high sensitivity and selectivity, accompanied by obvious fluorescence emission enhancement (504 nm for Al3+ and 575 nm for Zn2+). The detection limits were found to be 8.30 x 10(-8) M for Al3+ and 1.24 x 10(-7) M for Zn2+. The binding mechanisms between BDNOL and Al3+/Zn2+ ions were supported by H-1 NMR and HR-MS analysis, and a density functional theory (DFT) study. The sensing behavior was also studied with molecular logic functions of OR, AND, and NOT gates. Furthermore, the fluorescent sensor was successfully used to recognize Al3+ and Zn2+ in living cells, suggesting that this simple biosensor has great potential in biological imaging applications.

  • 260.
    Liu, Jian Quan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Mat Sci, Xuzhou 221116, Jiangsu, Peoples R China.
    Chen, Xinyi
    Shatskiy, Andrey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Kärkäs, Markus D.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Wang, Xiang-Shan
    Silver-Mediated Synthesis of Substituted Benzofuran- and Indole-Pyrroles via Sequential Reaction of ortho-Alkynylaromatics with Methylene Isocyanides2019In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 84, no 14, p. 8998-9006Article in journal (Refereed)
    Abstract [en]

    A silver-mediated reaction between 2-ethynyl-3-(1-hydroxyprop-2-yn-1-yl)phenols or 2-ethyn-yl-3-(1-hydroxy-prop-2-yn-1-yl)anilines and methylene isocyanides has been developed. A sequential 5-endo-dig cyclization and [3 + 2] cycloaddition process is proposed. This synthetic strategy is atom- and step-efficient and applicable to a broad scope of substrates, allowing the synthesis of valuable substituted benzofuran- and indole-pyrroles in moderate to high yields.

  • 261.
    Liu, Jianhua
    et al.
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Jia, Donglin
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Gardner, James M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala Univ, Dept Chem Angstrom, Phys Chem, S-75120 Uppsala, Sweden..
    Zhang, Xiaoliang
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Metal nanowire networks: Recent advances and challenges for new generation photovoltaics2019In: MATERIALS TODAY ENERGY, ISSN 2468-6069, Vol. 13, p. 152-185Article, review/survey (Refereed)
    Abstract [en]

    Transparent conducting electrodes which allow photons passing through and simultaneously transfers the charge carriers are critical for the construction of high-performance photovoltaic cells. Electrodes based on metal oxides, such as indium-doped tin oxide (ITO) or fluorine-doped tin oxide (FTO), may have limited application in new generation flexible solar cells, which employ solution-processed roll-to-roll or ink-printing techniques toward large-area-fabrication approach, due to their brittleness and poor mechanical properties. Metal nanowire network (MNWN) emerges as a highly potential alternative candidate instead of ITO or FTO due to the high transparency, low sheet resistance, low cost, solution processable and compatibility with a flexible substrate for high throughput production. This feature article systematically summarizes the recent advances of the MNWNs, including new concepts and emerging strategies for the synthesis of metal nanowires (MNWs), various approaches for the preparation of MNWNs and comprehensively discusses the novel MNWN electrodes prepared on different substrates. The state-of-the-art new generation solar cell devices, such as transparent, flexible and light-weight solar cells, with MNWN as a transparent conductive electrode are emphasized. Finally, the opportunities and challenges for the development of MNWN electrodes toward application in the new generations of photovoltaic devices are discussed.

  • 262.
    Liu, Jian-Quan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Shatskiy, Andrey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Matsuura, Bryan S.
    NYU, Dept Chem, New York, NY 10003 USA..
    Kärkäs, Markus D.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Recent Advances in Photoredox Catalysis Enabled Functionalization of alpha-Amino Acids and Peptides: Concepts, Strategies and Mechanisms2019In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, Vol. 51, no 14, p. 2759-2791Article, review/survey (Refereed)
    Abstract [en]

    The selective modification of alpha-amino acids and peptides constitutes a pivotal arena for accessing new peptide-based materials and therapeutics. In recent years, visible light photoredox catalysis has appeared as a powerful platform for the activation of small molecules via single-electron transfer events, allowing previously inaccessible reaction pathways to be explored. This review outlines the recent advances, mechanistic underpinnings, and opportunities of applying photoredox catalysis to the expansion of the synthetic repertoire for the modification of specific amino acid residues. 1 Introduction 2 Visible-Light-Mediated Functionalization of alpha-Amino Acids 2.1 Decarboxylative Functionalization Involving Redox-Active Esters 2.2 Direct Decarboxylative Coupling Strategies 2.3 Hypervalent Iodine Reagents 2.4 Dual Photoredox and Transition-Metal Catalysis 2.5 Amination and Deamination Strategies 3 Photoinduced Peptide Diversification 3.1 Gese-Type Bioconjugation Methods 3.2 Peptide Macrocyclization through Photoredox Catalysis 3.3 Biomolecule Conjugation through Arylation 3.4 C-H Functionalization Manifolds 4 Conclusions and Outlook

  • 263.
    Liu, Jian-Quan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Chem Engn, Xuzhou 221116, Jiangsu, Peoples R China.
    Shen, Xuanyu
    Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Chem Engn, Xuzhou 221116, Jiangsu, Peoples R China..
    Shatskiy, Andrey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Zhou, Enlong
    Shandong Agr Univ, Coll Chem & Mat Sci, Tai An 271000, Shandong, Peoples R China..
    Kärkäs, Markus D.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Wang, Xiang-Shan
    Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Chem Engn, Xuzhou 221116, Jiangsu, Peoples R China..
    Silver-Induced [3+2] Cycloaddition of Isocyanides with Acyl Chlorides: Regioselective Synthesis of 2,5-Disubstituted Oxazoles2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed)
    Abstract [en]

    A silver-induced cycloaddition of isocyanides with acyl chlorides has been developed. This transition metal-catalyzed strategy provides an effective and scalable approach for the formation of 2,5-disubstituted oxazoles in good to high yields. The employed silver-based MOF catalyst can be efficiently recycled without compromising the yield.

  • 264.
    Liu, Jun
    et al.
    Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Wood & Paper Chem, Porthansgatan 3-5, FI-20500 Turku, Finland.;Jiangsu Univ, Dept Environm & Safety, Biofuels Inst, Zhenjiang 212013, Peoples R China..
    Leppanen, Ann-Sofie
    Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Wood & Paper Chem, Porthansgatan 3-5, FI-20500 Turku, Finland..
    Kisonen, Victor
    Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Wood & Paper Chem, Porthansgatan 3-5, FI-20500 Turku, Finland..
    Willfor, Stefan
    Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Wood & Paper Chem, Porthansgatan 3-5, FI-20500 Turku, Finland..
    Xu, Chunlin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Wood & Paper Chem, Porthansgatan 3-5, FI-20500 Turku, Finland..
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Insights on the distribution of substitutions in spruce galactoglucomannan and its derivatives using integrated chemo-enzymatic deconstruction, chromatography and mass spectrometry2018In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 112, p. 616-625Article in journal (Refereed)
    Abstract [en]

    Accurate determination of the distribution of substitutions in the primary molecular structure of heteropolysaccharides and their derivatives is a prerequisite for their increasing application in the pharmaceutical and biomedical fields, which is unfortunately hindered due to the lack of effective analytical techniques. Acetylated galactoglucomannan (GGM) is an abundant plant polysaccharide as the main hemicellulose in softwoods, and therefore constitutes an important renewable resource from lignocellulosic biomass for the development of bioactive and functional materials. Here we present a methodology for profiling the intramolecular structure of spruce GGM and its chemical derivatives (cationic, anionic, and benzoylated) by combining chemo-enzymatic hydrolysis, liquid chromatography, and mass spectrometry. Fast identification and qualitative mass profiling of GGM and its derivatives was conducted using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF-MS) and electrospray ionization mass spectrometry (ESI-MS). Tandem mass fragmentation analysis and its hyphenation with hydrophilic interaction liquid chromatography (HILIC-ESI-MS/MS) provide further insights on the substitution placement of the GGM oligosaccharides and its derivatives. This method will be useful in understanding the structure-function relationships of native GGM and their derivatives, and therefore facilitate their potential application. 

  • 265.
    Liu, Min
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    DFT calculations of initial localized corrosion of aluminum: Influence of aqueous ad-layer, chloride ions, and intermetallic particles2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Localized corrosion of aluminum (Al, here including Al alloys) involves a series of physico-chemical processes at the interface between the metal and the aqueous ad-layer or the aqueous solution. The mechanisms that govern localized corrosion are quite complex and have been the subject of many experimental studies. Efforts to improve our understanding through computational studies have so far been much more limited. The primary aim of this Doctoral Thesis was to apply Density Functional Theory (DFT), together with some Molecular Dynamics calculations (limited effort), to gain a deeper mechanistic understanding of some of the most influential factors for the initiation of localized corrosion of Al: chloride ions, intermetallic particles (IMPs) and the presence of an aqueous ad-layer on the solid phase.In the scientific literature three scenarios have been proposed for the interaction of chloride ions with an aluminum and/or passive aluminum surface: through adsorption onto the passive layer, through breakdown of the same layer or through migration of chloride ions into the layer. DFT-calculations have been able to explore these scenarios in more detail, and provide evidence that chloride ions induce partial de-passivation in several ways. On the bare Al surface, chloride ions may inhibit the re-passivation through competitive adsorption with oxygen molecules, as suggested by density of state calculations. Chloride ions are also found to migrate via oxygen vacancies into the inner part of the investigated aluminum oxide films (α- and γ-Al2O3), where a critical amount of accumulated chloride can promote meta-stable pitting propagation. γ-Al2O3 exhibits a more open structure than α-Al2O3, resulting in a lower energy barrier for chloride migration.Micro-galvanic effects induced by Volta potential differences between representative intermetallic particles (Mg2Si and Al2Cu) and the surrounding Al matrix were predicted by calculating the work function of the bare surfaces of these phases with DFT. These values vary with crystalline face orientation and with terminal atomic configuration in the outmost surface layer. Calculated Volta potential differences between IMPs and Al show a reasonable agreement with reported experimental data, and suggest the possibility of predicting the nobility of specific IMPs relative to Al. Moreover, both DFT and scanning Kelvin probe force microscopy show evidence of electrochemical nobility inversion of Mg2Si versus Al upon adsorption of pure water ad-layers. This implies that an originally- 2 -cathodic Mg2Si phase becomes anodic compared to Al upon water adsorption, and is attributed to surface relaxation according to DFT calculations. With subsequent introduction of chloride ions into the water ad-layer, the nobility inversion of both Mg2Si and Al2Cu retains. This is due to a strong oxidizing effect of water on Al, while the effect of chloride seems less pronounced.In all, these and other examples presented show that DFT-calculations can provide more detailed atomistic and molecular information on physico-chemical processes governing localized corrosion of Al than experiments alone can do.

  • 266.
    Liu, Min
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, National Center for Materials Service Safety.
    Jin, Ying
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    A DFT-Study of Cl Ingress into α-Al2O3(0001) and Al(111) and Its Possible Influence on Localized Corrosion of Al2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 11, p. C3124-C3130Article in journal (Refereed)
    Abstract [en]

    Ingress of chloride into alpha-Al2O3(0001) and Al(111) was calculated by first-principles theory calculations by considering Cl insertion into Al or O vacancies within alpha-Al2O3(0001) or into vacancy or interstitial sites within Al(111). For alpha-Al2O3, the formation of an O vacancy is energetically more favorable than of an Al vacancy. The insertion of Cl into an O vacancy is also more favorable than into an Al vacancy. A high energy-barrier has been derived for Cl transport within the neighboring O vacancies. In addition, the work function decreases with Cl ingress into the interior of the oxide. For Al(111), Cl insertion into either an Al vacancy or an interstitial site is less favorable compared to the insertion into alpha-Al2O3. The work function only changes slightly with Cl insertion into an Al vacancy. Moreover, the pre-inserted Cl reduces the energy-barrier for further Cl ingress into alpha-Al2O3, whereas Cl tends to stay in the sub-surface layer of Al(111), suggesting Cl accumulation at the Al2O3/Al.

  • 267.
    Liu, Min
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, National Center for Materials Service Safety.
    Jin, Ying
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Co-adsorption of H2O, OH, and Cl on aluminum and intermetallic surfaces and its effects on the work function studied by DFT calculations2019In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, no 23Article in journal (Refereed)
    Abstract [en]

    The energetics of adsorption of H2O layers and H2O layers partially replaced with OH or Cl on an Al(111) surface and on selected surfaces of intermetallic phases, Mg2Si and Al2Cu, was studied by first-principle calculations using the density function theory (DFT). The results show that H2O molecules tended to bind to all investigated surfaces with an adsorption energy in a relatively narrow range, between -0.8 eV and -0.5 eV, at increased water coverage. This can be explained by the dominant role of networks of hydrogen bonds at higher H2O coverage. On the basis of the work function, the calculated Volta potential data suggest that both intermetallic phases became less noble than Al(111); also, the Volta potential difference was larger than 1 V when the coverage of the Cl-containing ad-layer reached one monolayer. The energetics of H2O dissociation and substitution by Cl as well as the corresponding work function of each surface were also calculated. The increase in the work function of the Al(111) surface was attributed to the oxidation effect during H2O adsorption, whereas the decrease of the work function for the Mg2Si(111)-Si surface upon H2O adsorption was explained by atomic and electronic rearrangements in the presence of H2O and Cl.

  • 268.
    Liu, Min
    et al.
    University of Science and Technology Beijing, Beijing, 100083, China.
    Jin, Ying
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Zhang, Chuanhui
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Wen, Lei
    University of Science and Technology Beijing, National Center for Materials Service Safety.
    Density-functional theory investigation of Al pitting corrosion in electrolyte containing chloride ions2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 357, p. 2028-2038Article in journal (Refereed)
    Abstract [en]

    The behavior of chloride ions (Cl-) and oxygen species (the oxygen atom, O or molecular oxygen, O-2) on Al(1 1 1) surface has been studied by density functional theory calculations in order to deepen the molecular understanding of fundamental processes leading to pitting of aluminum (Al). The adsorption behavior of individual species, Cl-, O atom and O-2 was determined first. Subsequently, three possible scenarios in different pitting stages were modeled exploring the repassivation and dissolution of Al in neutral electrolyte containing Cl-. In scenario i, it was found that Cl- can hardly destroy even an O-monolayer on Al(1 1 1) surface, however may lead to the elongation of Al-O bond and the weakened binding between the first Al layer and subsequent Al layers. Both O-2 and Cl- were simultaneously introduced onto Al(1 1 1) in scenario ii. The result showed a weakened Al-O interaction and an intensive hybridization peak at -0.18 Ha between Al-3p with Cl-3p suggesting insufficient repassivation behavior of Al under this condition. Finally, scenario iii mimicked different local environmental conditions in pits formed on Al. At low coverage of Cl-, chloride ions had little effect on surface relaxation. The interaction among chloride ions and Al surface became stronger as Cl- coverage increased. Surface Al atoms dissolved gradually and substructures such as AlCl3 and Al2C15 formed when the coverage was larger than 2/3 ML of a monolayer.

  • 269.
    Liu, Peng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Wang, Linqin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Karlsson, Karl Martin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Hao, Yan
    Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Xu, Bo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Boschloo, Gerrit
    Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Molecular Engineering of D-pi-A Type of Blue-Colored Dyes for Highly Efficient Solid-State Dye-Sensitized Solar Cells through Co-Sensitization2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 42, p. 35946-35952Article in journal (Refereed)
    Abstract [en]

    A novel blue-colored organic donor-pi-acceptor sensitizer, the so-called MKA16 dye, has been employed to construct solid-state dye-sensitized solar cells (ssDSSCs). Using 2,2',7-,7'-tetrakis(N,N-di-p-methoxyphenyl-amine) 9,9'-spirobifuorene (Spiro-OMeTAD) as hole-transport material, a good conversion efficiency of 5.8% was recorded for cells based on the MKA16 dye and a high photovoltage of 840 mV in comparison with 5.6% efficiency using the known (Dyenamo Blue) dye. By co-sensitization using the orange-colored D35 dye and MKA16 together, the solid-state solar cells showed an excellent efficiency of 7.5%, with a high photocurrent of 12.41 mA cm(-2) and open-circuit voltage of 850 mV. The results show that the photocurrent of ssDSSCs can be significantly improved by co-sensitization mainly attributed to the wider light absorption range contributing to the photocurrent. In addition, results from photo-induced absorption spectroscopy show that the dye regeneration is efficient in co-sensitized solar cells. The current results possible routes of improving the design of aesthetic and highly efficient ssDSSCs.

  • 270.
    Liu, Tianqi
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Zhang, Biaobiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Iron-Based Molecular Water Oxidation Catalysts: Abundant, Cheap, and Promising2019In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 14, no 1, p. 31-43Article, review/survey (Refereed)
    Abstract [en]

    An efficient and robust water oxidation catalyst based on abundant and cheap materials is the key to converting solar energy into fuels through artificial photosynthesis for the future of humans. The development of molecular water oxidation catalysts (MWOCs) is a smart way to achieve promising catalytic activity, thanks to the clear structures and catalytic mechanisms of molecular catalysts. Efficient MWOCs based on noble-metal complexes, for example, ruthenium and iridium, have been well developed over the last 30 years; however, the development of earth-abundant metal-based MWOCs is very limited and still challenging. Herein, the promising prospect of iron-based MWOCs is highlighted, with a comprehensive summary of previously reported studies and future research focus in this area.

  • 271.
    Lopez-Goldar, Xose
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). CSIC, Mision Biol Galicia, Pontevedra, Spain.;Ohio State Univ, Dept Plant Pathol, Columbus, OH 43210 USA.;INIA, Forest Res Ctr, Dept Forest Ecol & Genet, Madrid, Spain..
    Villari, Caterina
    Ohio State Univ, Dept Plant Pathol, Columbus, OH 43210 USA.;Univ Georgia, Daniel B Warnell Sch Forestry & Nat Resources, Athens, GA 30602 USA..
    Bonello, Pierluigi
    Ohio State Univ, Dept Plant Pathol, Columbus, OH 43210 USA..
    Borg-Karlson, Anna-Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Grivet, Delphine
    INIA, Forest Res Ctr, Dept Forest Ecol & Genet, Madrid, Spain.;Univ Valladolid, INIA, Sustainable Forest Management Res Inst, Palencia, Spain..
    Zas, Rafael
    CSIC, Mision Biol Galicia, Pontevedra, Spain..
    Sampedro, Luis
    CSIC, Mision Biol Galicia, Pontevedra, Spain..
    Inducibility of Plant Secondary Metabolites in the Stem Predicts Genetic Variation in Resistance Against a Key Insect Herbivore in Maritime Pine2018In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, article id 1651Article in journal (Refereed)
    Abstract [en]

    Resistance to herbivores and pathogens is considered a key plant trait with strong adaptive value in trees, usually involving high concentrations of a diverse array of plant secondary metabolites (PSM). Intraspecific genetic variation and plasticity of PSM are widely known. However, their ecology and evolution are unclear, and even the implication of PSM as traits that provide direct effective resistance against herbivores is currently questioned. We used control and methyl jasmonate (MJ) induced clonal copies of genotypes within families from ten populations of the main distribution range of maritime pine to exhaustively characterize the constitutive and induced profile and concentration of PSM in the stem phloem, and to measure insect herbivory damage as a proxy of resistance. Then, we explored whether genetic variation in resistance to herbivory may be predicted by the constitutive concentration of PSM, and the role of its inducibility to predict the increase in resistance once the plant is induced. We found large and structured genetic variation among populations but not between families within populations in resistance to herbivory. The MJ-induction treatment strongly increased resistance to the weevil in the species, and the genetic variation in the inducibility of resistance was significantly structured among populations, with greater inducibility in the Atlantic populations. Genetic variation in resistance was largely explained by the multivariate concentration and profile of PSM at the genotypic level, rather than by bivariate correlations with individual PSM, after accounting for genetic relatedness among genotypes. While the constitutive concentration of the PSM blend did not show a clear pattern of resistance to herbivory, specific changes in the chemical profile and the increase in concentration of the PSM blend after MJ induction were related to increased resistance. To date, this is the first example of a comprehensive and rigorous approach in which inducibility of PSM in trees and its implication in resistance was analyzed excluding spurious associations due to genetic relatedness, often overlooked in intraspecific studies. Here we provide evidences that multivariate analyses of PSM, rather than bivariate correlations, provide more realistic information about the potentially causal relationships between PSM and resistance to herbivory in pine trees.

  • 272.
    Lundberg, Helena
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Tinnis, Fredrik
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Adolfsson, Hans
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Zirconium catalyzed amide formation without water scavenging2019In: Applied organometallic chemistry, ISSN 0268-2605, E-ISSN 1099-0739, article id e5062Article in journal (Refereed)
    Abstract [en]

    A scalable homogeneous metal-catalyzed protocol for direct amidation of carboxylic acids is presented. The use of 2-10 mol% of the commercially available Zr(Cp)(2)(OTf)(2)center dot THF results in high yields of amides at moderate temperature, using an operationally convenient reaction protocol that circumvents the use of water scavenging techniques.

  • 273.
    Lynch, Aisling
    et al.
    Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Limerick, Ireland..
    Jia, Lijun
    Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Limerick, Ireland..
    Svärd, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Limerick, Ireland.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Univ Limerick, Synth & Solid State Pharmaceut Ctr, Bernal Inst, Dept Chem Sci, Limerick, Ireland..
    Crystal Growth of Salicylamide in Organic Solvents2018In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 18, no 12, p. 7305-7315Article in journal (Refereed)
    Abstract [en]

    Salicylamide was used as a model active pharmaceutical compound to investigate the crystal growth process and its associated kinetics. The impact of organic solvent, supersaturation, and temperature on the crystal growth was studied. The multiparticle crystal growth kinetics were determined using the seeded isothermal desupersaturation method and modeled using several growth rate equations, using different representations of the driving force. The results showed that crystal growth is significantly influenced by experimental conditions. Within the range of experimental conditions, the growth kinetics was affected strongly by the temperature and to a lesser degree by solvent choice. Comparison of the growth order parameter reveals a surface integration controlled growth. Higher than expected activation energies indicate desolvation as a governing process. A comparison of the influence of the solvent on the crystal growth of salicylamide against previously published approximate data at much higher supersaturation shows good agreement, but the influence on the interfacial energy is opposite to that observed for crystal nucleation. In a detailed comparison with crystal growth data of salicylic acid, there is a consistency in the influence of the solvent on the crystal growth of the two compounds. Salicylamide growth kinetics is more strongly affected by increasing temperature than salicylic acid.

  • 274.
    Långberg, Marie
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. SWERIM, SE-16407 Kista, Sweden..
    Örnek, Cem
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Zhang, Fan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Cheng, J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Liu, M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Granaes, E.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Wiemann, C.
    Res Ctr Julich, Peter Grunberg Inst PGI 6, D-52425 Julich, Germany..
    Gloskovskii, A.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Matveyev, Y.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Kulkarni, S.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Noei, H.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Keller, T. F.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;Univ Hamburg, Phys Dept, D-20355 Hamburg, Germany..
    Lindell, D.
    SWERIM, SE-16407 Kista, Sweden..
    Kivisakk, U.
    AB Sandvik Mat Technol, SE-81181 Sandviken, Sweden..
    Lundgren, E.
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Stierle, A.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;Univ Hamburg, Phys Dept, D-20355 Hamburg, Germany..
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Characterization of Native Oxide and Passive Film on Austenite/Ferrite Phases of Duplex Stainless Steel Using Synchrotron HAXPEEM2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 11, p. C3336-C3340Article in journal (Refereed)
    Abstract [en]

    A new measurement protocol was used for microscopic chemical analysis of surface oxide films with lateral resolution of 1 mu m. The native air-formed oxide and an anodic passive film on austenite and ferrite phases of a 25Cr-7Ni super duplex stainless steel were investigated using synchrotron hard X-ray photoemission electron microscopy (HAXPEEM). Pre-deposited Pt-markers, in combination with electron backscattering diffraction mapping (EBSD), allowed analysis of the native oxide on individual grains of the two phases and the passive film formed on the same area after electrochemical polarization of the sample. The results showed a certain difference in the composition of the surface films between the two phases. For the grains with (001) crystallographic face // sample surface, the native oxide film on the ferrite contained more Cr oxide than the austenite. Anodic polarization up to 1000 mV/(Ag/AgCl) in 1M NaCl solution at room temperature resulted in a growth of the Cr- and Fe-oxides, diminish of Cr-hydroxide, and an increased proportion of Fe3+ species. by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

  • 275.
    López Durán, Verónica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Chemical Modification of Cellulose Fibres and Fibrils for Design of New Materials2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to the growing interest in biobased materials in today’s society, where the need for a cyclic economy is obvious, there has been a huge increase in the  interest for using cellulose due to its excellent mechanical and chemical properties. However, the properties of cellulose have to be modified and improved in order to satisfy advanced material applications where the cellulose properties can be tuned to fit the properties of other components in composite mixtures. This thesis explores the heterogeneous chemical modification of cellulose for improved material properties of cellulose-based materials and the use of cellulose fibres and fibrils in novel applications.

    In the first part of the work described in this thesis, a fundamental study was performed to clarify how the chemical composition and the fibre/fibril structure of the cellulose following chemical modification affect the material properties. The second part of the work was aimed at exploring the potential for using the chemically modified fibres/fibrils in novel material applications. 

    Lignocellulosic fibres with different chemical compositions were modified by periodate oxidation and borohydride reduction, and it was found that the most important factor was the amount of holocellulose present in the fibres, since lignin-rich fibres were less reactive and less responsive to the treatments. Despite the lower reactivity of lignin-rich fibres, it was however possible to improve their mechanical properties and to achieve a significant increase in the compressive strength of papers prepared from modified unbleached kraft fibres.

    The chemical modifications were then expanded to nine different molecular structures and two different degrees of modification. Fibres modified at low degrees of modification were used to prepare handsheets, followed by mechanical and physical characterization. Highly modified fibres were also used to prepare cellulose nanofibrils (CNFs). It was found that the properties of handsheets and films prepared from modified fibres/fibrils are highly dependent on the chemical structure of the modified cellulose and, as an example, the ductility was greatly improved by converting secondary alcohols to primary alcohols. A detailed analysis of the modified fibres and fibrils also showed that, due to the heterogeneous chemical reaction used, the modified fibrils had a core-shell structure with a shell of modified cellulose with a lower crystalline order surrounding a core of crystalline cellulose. The results also showed that the chemical structure of the modified shell dramatically affects the interaction with moisture. Materials from fibrils containing covalent crosslinks have shown to be less sensitive to moisture at the cost of being more brittle. 

    In a different application, modified CNFs were used as paper strength additives. Three differently modified CNFs were used: carboxymethylated CNFs, periodate-oxidised carboxymethylated CNFs and dopamine-grafted carboxymethylated CNFs. The properties of these CNFs were compared with that of a microfibrillated cellulose from unbleached kraft fibres. In general, a great improvement in the dry mechanical properties of handsheets was observed with the addition of the periodate-oxidised oxidised and dopamine-grafted modified fibrils, whereas only the periodate-oxidised carboxymethylated CNFs improved the wet strength.

    Finally, it was found that the chemically modified fibres could be used to prepare a novel low-density material with good mechanical strength, both wet and dry, and excellent shape recovery capacity in the wet state after mechanical compression. The fibre networks were produced by solvent exchange from water to acetone followed by air drying at room temperature. The properties of the fibre networks could also fairly easily be tuned in terms of porosity, density and strength.

  • 276.
    López-Goldar, Xosé
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Villari, C.
    Bonello, P.
    Borg-Karlson, Anna-Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Grivet, D.
    Sampedro, L.
    Zas, R.
    Genetic variation in the constitutive defensive metabolome and its inducibility are geographically structured and largely determined by demographic processes in maritime pine2019In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 107, no 5, p. 2464-2477Article in journal (Refereed)
    Abstract [en]

    Interspecific phenotypic variation in plant secondary metabolites (PSM) is often explained by biotic and abiotic factors. However, patterns of variation within species do not clearly fit the theoretical predictions. Exploring how genetics, environment and demographic processes shape such variation among and within populations is crucial for understanding evolution of PSM, particularly in long-lived plants such as forest trees. Here, we quantified genetic variation in PSM among and within populations, and explored drivers of local adaptation by studying the role of climate as a source of population differentiation in PSM of maritime pine. Constitutive profile and concentrations of 63 PSM and their herbivory-associated inducibility were determined in the bark of 130 clonally replicated genotypes with known familial structure from 10 populations covering the distribution range of the species. We compared neutral and quantitative population genetic differentiation of PSM (F ST and Q ST ). Also, we accounted for population genetic structure and kinship among individuals when exploring climate–trait relationships. We found large population differentiation and additive genetic variation in constitutive PSM. Many PSM were inducible, although very low genetic variation was observed with respect to their inducibility. Q ST –F ST comparisons suggest that differentiation of most diterpenes, monoterpenes, and phenolics can be explained by neutral demographic processes. Spatially heterogeneous selection across populations leading to local adaptation was only found for total constitutive sesquiterpenes and a few individual PSM. After accounting for population genetic structure, only the constitutive concentration of two sesquiterpenes showing signs of diversifying selection was predicted by climate, with decreasing concentrations along a growth-prone climatic gradient. Synthesis. Evolutionary patterns of plant secondary metabolites depended on their chemical nature, with neutral differentiation governing most plant secondary metabolites. Evidence of local adaptation was only found for total constitutive sesquiterpenes and a few individual plant secondary metabolites. The low genetic variation in the inducibility of plant secondary metabolites suggests a conserved model of defensive induction in this species. Since population differentiation linked to past demographic history could lead to false positives of adaptive differentiation signals, accounting for the genetic relatedness among populations is required to infer the environmental determinants of intraspecific genetic variation in putatively adaptive traits such as plant defences.

  • 277.
    MacKenzie, Jordan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Swerin, Agne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Turbulent stress measurements of fibre suspensions in a straight pipe2018In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 30, no 2, article id 025104Article in journal (Refereed)
    Abstract [en]

    The focus of the present work is an experimental study of the behaviour of semi-dilute, opaque fibre suspensions in fully developed cylindrical pipe flows. Measurements of the normal and turbulent shear stress components and the mean flow were acquired using phase-contrast magnetic resonance velocimetry. Two fibre types, namely, pulp fibre and nylon fibre, were considered in this work and are known to differ in elastic modulus. In total, three different mass concentrations and seven Reynolds numbers were tested to investigate the effects of fibre interactions during the transition from the plug flow to fully turbulent flow. It was found that in fully turbulent flows of nylon fibres, the normal, < u(z)u(z)>(+), and shear, < u(z)u(z)>(+) (note that <.> is the temporal average, u is the fluctuating velocity, z is the axial or streamwise component, and r is the radial direction), turbulent stresses increased with Reynolds number regardless of the crowding number (a concentration measure). For pulp fibre, the turbulent stresses increased with Reynolds number when a fibre plug was present in the flow and were spatially similar in magnitude when no fibre plug was present. Pressure spectra revealed that the stiff, nylon fibre reduced the energy in the inertial-subrange with an increasing Reynolds and crowding number, whereas the less stiff pulp fibre effectively cuts the energy cascade prematurely when the network was fully dispersed.

  • 278.
    Magallanes, Gabriel
    et al.
    Univ Michigan, Dept Chem, Willard Henry Dow Lab, 930 North Univ Ave, Ann Arbor, MI 48109 USA..
    Kärkäs, Markus D.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Univ Michigan, Dept Chem, Willard Henry Dow Lab, 930 North Univ Ave, Ann Arbor, MI 48109 USA..
    Bosque, Irene
    Univ Michigan, Dept Chem, Willard Henry Dow Lab, 930 North Univ Ave, Ann Arbor, MI 48109 USA..
    Lee, Sudarat
    Univ Michigan, Dept Chem, Willard Henry Dow Lab, 930 North Univ Ave, Ann Arbor, MI 48109 USA..
    Maldonado, Stephen
    Univ Michigan, Dept Chem, Willard Henry Dow Lab, 930 North Univ Ave, Ann Arbor, MI 48109 USA.;Univ Michigan, Program Appl Phys, Ann Arbor, MI 48109 USA..
    Stephenson, Corey R. J.
    Univ Michigan, Dept Chem, Willard Henry Dow Lab, 930 North Univ Ave, Ann Arbor, MI 48109 USA..
    Selective C-O Bond Cleavage of Lignin Systems and Polymers Enabled by Sequential Palladium-Catalyzed Aerobic Oxidation and Visible-Light Photoredox Catalysis2019In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 9, no 3, p. 2252-2260Article in journal (Refereed)
    Abstract [en]

    Lignin, which is a highly cross-linked and irregular biopolymer, is nature's most abundant source of aromatic compounds and constitutes an attractive renewable resource for the production of aromatic commodity chemicals. Herein, we demonstrate a practical and operationally simple two-step degradation approach involving Pd-catalyzed aerobic oxidation and visible-light photoredox-catalyzed reductive fragmentation for the chemoselective cleavage of the beta-O-4 linkage-the predominant linkage in lignin for the generation of lower-molecular-weight aromatic building blocks. The developed strategy affords the beta-O-4 bond cleaved products with high chemoselectivity and in high yields, is amenable to continuous flow processing, operates at ambient temperature and pressure, and is moisture- and oxygen-tolerant.

  • 279.
    Mageroy, Melissa H.
    et al.
    Norwegian Inst Bioecon Res, Dept Mol Plant Biol, N-1431 As, Norway..
    Christiansen, Erik
    Norwegian Inst Bioecon Res, Dept Mol Plant Biol, N-1431 As, Norway..
    Langstrom, Bo
    Swedish Univ Agr Sci, Dept Ecol, S-75007 Uppsala, Sweden..
    Borg-Karlson, Anna-Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Solheim, Halvor
    Norwegian Inst Bioecon Res, Dept Mol Plant Biol, N-1431 As, Norway..
    Bjorklund, Niklas
    Swedish Univ Agr Sci, Dept Ecol, S-75007 Uppsala, Sweden..
    Zhao, Tao
    Orebro Univ, Sch Sci & Technol, SE-70182 Orebro, Sweden..
    Schmidt, Axel
    Max Planck Inst Chem Ecol, Dept Biochem, D-07745 Jena, Germany..
    Fossdal, Carl Gunnar
    Norwegian Inst Bioecon Res, Dept Mol Plant Biol, N-1431 As, Norway..
    Krokene, Paal
    Norwegian Inst Bioecon Res, Dept Mol Plant Biol, N-1431 As, Norway..
    Priming of inducible defenses protects Norway spruce against tree-killing bark beetles2020In: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 43, no 2, p. 420-430Article in journal (Refereed)
    Abstract [en]

    Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short-lived model plants such as Arabidopsis, but little is known about this phenomenon in long-lived plants like spruce. We compared the effects of pretreatment with sublethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48-year-old Norway spruce (Picea abies) trees to mass attack by a tree-killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees but largely avoided fungus-inoculated trees and MeJA-treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91-fold higher terpene concentrations compared with untreated trees, whereas application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus-inoculated trees is a result of direct induction of defenses, whereas resistance in MeJA-treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.

  • 280.
    Maier, Annika Carolin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Dynamics of Spent Nuclear Fuel Dissolution: Impact of Catalysis, Matrix Composition and Time Evolution2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Worldwide, nuclear power produces a large portion of the electricity that we consume every day. While nuclear energy comes with certain advantages, waste originating from its use is of particular concern. As of today, most countries are planning to store spent nuclear fuel in deep geological repositories to protect humans and the environment from this highly radiotoxic waste. Through a number of natural and engineered barriers, a repository is designed to remain intact and keep the radionuclides contained for millennia to come. To assess the safety of a repository, long-term predictions based on model systems are required. Given that one day the barriers of a repository fail, groundwater intrusion is inevitable. Once spent fuel is in contact with groundwater, the mobility of radionuclides in the environment is significantly enhanced. Spent nuclear fuel is a complex material which consists to around 95 % of UO2. The remainders are fission products and heavier actinides. In this thesis a bottom up approach is used to study dissolution of UO2 based model systems with a particular focus on dissolution induced by H2O2. H2O2 forms upon water radiolysis and can enhance UO2 dissolution. The mechanism for H2O2 consumption on metals and metal oxides is therefore revisited. It was found that the mechanism for catalytic decomposition of H2O2 on Pd differs from that on metal oxides. In addition, coumarin was demonstrated to be an efficient scavenger for reaction intermediates i.e. HO . To simulate longterm dissolution under repository conditions, UO2 and Gd-doped UO2 pellets were leached to reach high H2O2 exposures. Surface passivation reducing the dissolution of UO2 pellets was found to be accompanied by the formation of an oxidized layer. Studtite, a urnayl peroxide mineral can passivate the UO2 surface under certain conditions. Upon exposure to g-radiation studtite was found to dissolve readily, inhibiting passivation of real spent fuel by this surface precipitate.

  • 281.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Barreiro Fidalgo, Alexandre
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    H2O2 Induced Dissolution of (U1–xGdx)O2 Pellets in Aqueous Solution – Impact of H2 and Consecutive ExposuresManuscript (preprint) (Other academic)
  • 282.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Benarosch, Anna
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering.
    El Jamal, Ghada
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Radiation induced dissolution of U3Si2 - A potential accident tolerant fuel2019In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 517, p. 263-267Article in journal (Refereed)
    Abstract [en]

    To assess the integrity of the accident tolerant fuel candidate U 3 Si 2 under geological repository conditions, the kinetics of γ-radiation- and H 2 O 2 - induced oxidative dissolution was studied. The experiments were performed in aqueous solutions containing 10 mM HCO 3 − and in solutions without added HCO 3 − . The same experiments were also performed on UO 2 for comparison. All experiments were performed using powder suspensions. The experiments show that U 3 Si 2 is less than one order of magnitude more reactive towards H 2 O 2 than is UO 2 . The dissolution yield of U 3 Si 2 slightly exceeds the theoretical yield (23%). In experiments with consecutive additions of H 2 O 2 in HCO 3 − solutions, the reactivity remains constant implying that no significant amount of a secondary phase is formed on the U 3 Si 2 surface. The dissolution of Si closely follows that of U in HCO 3 − solution. In solutions without added HCO 3 − the reactivity towards H 2 O 2 is reduced by a factor less than 2. The dissolution is slightly slower than in HCO 3 − containing solutions but precipitation of U is observed after some time. The results of consecutive additions of H 2 O 2 to the HCO 3 − free system shows that the reactivity is decreasing for every addition. This indicates that a secondary phase is formed. XRD shows that the secondary phase is studtite. The irradiation experiments show that the surface area normalized radiation chemical yields for uranium dissolution for U 3 Si 2 and UO 2 in HCO 3 − solution differ by a factor 5–10 in favour of UO 2 . This difference can largely be attributed to the difference in dissolution yield.

  • 283.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Herceglija Iglebaek, Ena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Confirming the formation of hydroxyl radicals in the catalytic decomposition of H2O2 on metal oxides using coumarin as a probe2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed)
    Abstract [en]

    Hydrogen peroxide can be catalytically decomposed to O2 and H2O on metal oxide surfaces in contact with aqueous solutions containing H2O2. The initial step in this process has been proposed to be the formation of surface‐bound hydroxyl radicals which has recently been verified using tris as a radical scavenger. Here, we make use of the unique fluorescent product 7‐hydroxycoumarin formed in the reaction between hydroxyl radicals and coumarin to probe the formation of surface‐bound hydroxyl radicals. The experiments clearly show that 7‐hydroxycoumarin is formed upon catalytic decomposition of H2O2 in aqueous suspensions containing ZrO2‐particles and coumarin, thereby confirming the formation of surface‐bound hydroxyl radicals in this process. The results are quantitatively compared to results on the same system using tris as a probe for hydroxyl radicals. The effects of the two probes on the system under study are compared and it is concluded that coumarin has a significantly lower impact on the system.

  • 284.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Iglebaek, Ena Herceglija
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Confirming the Formation of Hydroxyl Radicals in the Catalytic Decomposition of H2O2 on Metal Oxides Using Coumarin as a Probe2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 11, no 22, p. 5435-5438Article in journal (Refereed)
    Abstract [en]

    Hydrogen peroxide can be catalytically decomposed to O-2 and H2O on metal oxide surfaces in contact with aqueous solutions containing H2O2. The initial step in this process has been proposed to be the formation of surface-bound hydroxyl radicals which has recently been verified using tris as a radical scavenger. Here, we make use of the unique fluorescent product 7-hydroxycoumarin formed in the reaction between hydroxyl radicals and coumarin to probe the formation of surface-bound hydroxyl radicals. The experiments clearly show that 7-hydroxycoumarin is formed upon catalytic decomposition of H2O2 in aqueous suspensions containing ZrO2-particles and coumarin, thereby confirming the formation of surface-bound hydroxyl radicals in this process. The results are quantitatively compared to results on the same system using tris as a probe for hydroxyl radicals. The effects of the two probes on the system under study are compared and it is concluded that coumarin has a significantly lower impact on the system.

  • 285.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H22019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed)
    Abstract [en]

    To assess the influence of metallic inclusions (ϵ‐particles) on the dissolution of spent nuclear fuel under deep repository conditions, Pd‐catalyzed reactions of H2O2, O2 and UO22+ with H2 were studied using Pd‐powder suspensions. U(VI) can efficiently be reduced to less soluble U(IV) on Pd‐particles in the presence of H2. The kinetics of the reaction was found to depend on the H2 partial pressure at pH2≤5.1×10−2 bar. In comparison, the H2 pressure dependence for the reduction of H2O2 on Pd also becomes evident below 5.1×10−2 bar. Surface bound hydroxyl radicals are formed as intermediate species produced during the catalytic decomposition of H2O2 on oxide surfaces. While a significant amount of surface bound hydroxyl radicals were scavenged during the catalytic decomposition of H2O2 on ZrO2, no scavenging was observed in the same reaction on Pd. This indicates a different reaction mechanism for H2O2 decomposition on Pd compared to metal oxides and is in contrast to current literature. While Pd is an excellent catalyst for the synthesis of H2O2 from H2 and O2, a similar catalytic activity that was previously proposed for ZrO2 could not be confirmed.

  • 286.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kegler, Philip
    Klinkenberg, Martina
    Baena, Angela
    Finkeldei, Sarah
    Brandt, Felix
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    High Surface Conversion UO2 - Leaching Experiments as Model for Long-term Leaching of Spent Nuclear Fuel Under Deep Repository ConditionsManuscript (preprint) (Other academic)
  • 287. Makarova, I. V.
    et al.
    Kharitonov, D. S.
    Dobryden', Illia B.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Chernik, A. A.
    Corrosion Behavior in Acid and Alkaline Media of Nickel Coatings Deposited at Room Temperature2018In: Russian journal of applied chemistry, ISSN 1070-4272, E-ISSN 1608-3296, Vol. 91, no 9, p. 1441-1450Article in journal (Refereed)
    Abstract [en]

    Impedance spectroscopy, chronovoltammetry, chronopotentiometry, scanning electron microscopy, and atomic-force microscopy were used to examine the corrosion behavior in acid and alkaline media and the morphology of nickel coatings electrodeposited from acetate, tartrate, and isobutyrate electrolytes at a temperature of 20–25°C. Models describing the nickel corrosion processes in H2SO4 and NaOH solutions were suggested. It was found that nickel coatings formed from isobutyrate electrolytes have the highest corrosion resistance.

  • 288.
    Makarova, Irina
    et al.
    Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Technol Electrochem Prod & Elect Engn M, Sverdlova Str 13a, Minsk 220006, BELARUS.;LUT Univ, Sch Engn Sci, Dept Separat & Purificat, Yliopistonkatu 34, FI-53850 Lappeenranta, Finland..
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Kharitonov, Dmitry
    Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Technol Electrochem Prod & Elect Engn M, Sverdlova Str 13a, Minsk 220006, BELARUS.;Polish Acad Sci, Jerzy Haber Inst Catalysis & Surface Chem, Niezapominajek 8, PL-30239 Krakow, Poland..
    Kasach, Aliaksandr
    Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Technol Electrochem Prod & Elect Engn M, Sverdlova Str 13a, Minsk 220006, BELARUS..
    Ryl, Jacek
    Gdansk Univ Technol, Dept Electrochem Corros & Mat Engn, Narutowicza Str 11-12, PL-80233 Gdansk, Poland..
    Repo, Eveliina
    LUT Univ, Sch Engn Sci, Dept Separat & Purificat, Yliopistonkatu 34, FI-53850 Lappeenranta, Finland..
    Vuorinen, Esa
    Lulea Univ Technol, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    Nickel-nanodiamond coatings electrodeposited from tartrate electrolyte at ambient temperature2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 380, article id 125063Article in journal (Refereed)
    Abstract [en]

    In this study, nanocrystalline Ni and Ni-diamond coatings were obtained by electrodeposition from tartrate electrolyte at ambient temperature aiming at improving corrosion and wear properties of the material. The created surfaces were investigated with regard to microhardness, adhesion, wear- and corrosion-resistance. The various methods such as atomic force microscopy, scanning electron microscopy, electrochemical impedance spectroscopy and linear polarization technique were applied to study the coating surface properties. The introduction of nanodiamond particles into the coating led to a rougher surface structure and a bigger grain size in comparison to bare nickel coating. Our study shows that the addition of 5.10(-2) (g dm(-3)) of nanodiamonds to the plating bath is enough to obtain composite coatings with a clear increase in microhardness and wear resistance. The slightly improved corrosion resistance of the coating, decrease in corrosion current density from 0.41 to 0.14 mu A cm(-2) in neutral chloride-containing medium, and nobler values of the corrosion potential were also observed.

  • 289.
    Martinez-Abad, Antonio
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. AlbaNova University Centre.
    Giummarella, Nicola
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Differences in extractability under subcritical water reveal interconnected hemicellulose and lignin recalcitrance in birch hardwoods2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270Article in journal (Refereed)
    Abstract [en]

    Hardwoods constitute an essential renewable resource for the production of platform chemicals and bio-based materials. A method for the sequential extraction of hemicelluloses and lignin from hardwoods is proposed using subcritical water in buffered conditions without prior delignification. This allows the cascade isolation of mannan, xylan and lignin-carbohydrate complexes based on their extractability and recalcitrance in birch lignocellulose. The time evolution of the extraction was monitored in terms of composition, oligomeric mass profiling and sequencing of the hemicelluloses, and molecular structure of the lignin and lignin-carbohydrate complexes (LCCs) by heteronuclear single quantum coherence nuclear magnetic resonance (2D HSQC NMR). The minor mannan and pectin populations are easily extractable at short times (<5 min), whereas the major glucuronoxylan (GX) becomes enriched at moderate extraction times. Longer extraction times results in major hydrolysis exhibiting GX fractions with tighter glucuronation spacing and lignin enrichment. The pattern of acetylation and glucuronation in GX is correlated with extractability and with connectivity with lignin through LCCs. This interconnected molecular heterogeneity of hemicelluloses and lignin has important implications for their supramolecular assembly and therefore determines the recalcitrance of hardwood lignocellulosic biomass.

  • 290.
    Martinez-Abad, Antonio
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. Univ Alicante, Analyt Chem Nutr & Food Sci, Alicante, Spain.
    Jimenez-Quero, Amparo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Spruce hemicelluloses (galactoglucomannan and arabinoglucuronoxylan): Interplay with cellulose and lignin in softwoods2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 291.
    Martinez-Abad, Antonio
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Quero, Amparo Jimenez
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Berglund, Jennie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Giummarella, Nicola
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Wallenberg Wood Sci Ctr, Stockholm, Sweden.;KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Influence of the molecular structure of wood hemicelluloses on the recalcitrance of lignocellulosic biomass2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 292.
    Martins, Antonio
    et al.
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden..
    Pfirrmann, Thorsten
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden.;Martin Luther Univ Halle Wittenberg, Inst Physiol Chem, D-06114 Halle, Germany..
    Heessen, Stijn
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden.;Sanofi Aventis Deutschland GmbH, Global Business Dev & Licensing Consumer Healthca, D-65926 Frankfurt, Germany..
    Sundqvist, Gustav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Bulone, Vincent
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Andreasson, Claes
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden..
    Ljungdahl, Per O.
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden..
    Ssy5 is a signaling serine protease that exhibits atypical biogenesis and marked S1 specificity2018In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 293, no 22, p. 8362-8378Article in journal (Refereed)
    Abstract [en]

    Ssy5 is a signaling endoprotease that plays a key role in regulating central metabolism, cellular aging, and morphological transitions important for growth and survival of yeast (Saccharomyces cerevisiae) cells. In response to extracellular amino acids, Ssy5 proteolytically activates the transcription factors Stp1 and Stp2, leading to enhanced Ssy1-Ptr3-Ssy5 (SPS) sensor-regulated gene expression. Ssy5 comprises a catalytic (Cat) domain and an extensive regulatory prodomain. Ssy5 is refractory to both broad-spectrum and serine protease-specific inhibitors, confounding its classification as a protease, and no information about Ssy5's cleavage-site preferences and its mechanism of substrate selection is available. Here, using mutational and inhibition experiments, we investigated the biogenesis and catalytic properties of Ssy5 and conclusively show that it is a serine protease. Atypical for the majority of serine proteases, Ssy5's prodomain was obligatorily required in cis during biogenesis for the maturation of the proteolytic activity of the Cat domain. Autolysis and Stp1 and Stp2 cleavage occurred between a cysteine (at the P1 site) and a serine or alanine (at the P1 site) and required residues with short side chains at the P1 site. Substitutions in the Cat domain affecting substrate specificity revealed that residues Phe-634, His-661, and Gly-671 in the S1-binding pocket of this domain are important for Ssy5 catalytic function. This study confirms that the signaling protease Ssy5 is a serine protease and provides a detailed understanding of the biogenesis and intrinsic properties of this key enzyme in yeast.

  • 293. Matveev, V. V.
    et al.
    Markelov, D. A.
    Dvinskikh, Sergey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Shishkin, A. N.
    Tyutyukin, K. V.
    Penkova, A. V.
    Tatarinova, E. A.
    Ignat'Eva, G. M.
    Milenin, S. A.
    Investigation of Melts of Polybutylcarbosilane Dendrimers by 1H NMR Spectroscopy2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, no 1, article id 13710Article in journal (Refereed)
    Abstract [en]

    Melts of polybutylcarbosilane (PBC) dendrimers from third (G3) up to sixth (G6) generations are investigated by 1H NMR spectroscopy in a wide temperature range up to 493 K. At room temperature, NMR spectra of G3-G5 dendrimers exhibit resolved, solution-like spectra ("liquid" phase). In contrast, the spectrum of the G6 dendrimer is characterized by a single unresolved broad line at whole temperature range, which supports the presence of an anomalous phase state of G6 at temperatures higher than glass transition temperature. For the first time, an unexpected transition of G5 dendrimer from a molecular liquid state to an anomalous state/phase upon temperature increase has been detected using NMR data. Specifically, an additional wide background line appears in the G5 spectrum above 473 K, and this line corresponds to a G5 state characterized by restricted molecular mobility, i.e., a state similar to the "anomalous" phase of G6 melt. The fraction of the G5 dendrimers in "anomalous" phase at 493 K is approximately 40%. Analysis of the spectral shapes suggests that changes in the G5 dendrimers are reversible with temperature.

  • 294.
    Mazo, Juan J.
    et al.
    Univ Zaragoza, Dept Fis Mat Condensada, Zaragoza, Spain.;Univ Zaragoza, CSIC, Inst Ciencia Mat Aragon, Zaragoza, Spain..
    Martinez, Pedro J.
    Univ Zaragoza, CSIC, Inst Ciencia Mat Aragon, Zaragoza, Spain.;Univ Zaragoza, Dept Fis Aplicada, Zaragoza, Spain..
    Pedraz, Patricia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hennig, Jana
    Friedrich Schiller Univ Jena, Otto Schott Inst Mat Res OSIM, Lobdergraben 32, D-07743 Jena, Germany..
    Gnecco, Enrico
    Friedrich Schiller Univ Jena, Otto Schott Inst Mat Res OSIM, Lobdergraben 32, D-07743 Jena, Germany..
    Plowing-Induced Structuring of Compliant Surfaces2019In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 122, no 25, article id 256101Article in journal (Refereed)
    Abstract [en]

    The structures produced by a sharp tip scraping a compliant surface are modeled in the illustrative case of scan patterns formed by a series of parallel lines. This is made possible by a modified version of the Prandtl model for stick-slip friction, with an interaction energy landscape replicating the morphology of the evolving surface. As a result, a ripple motif emerges with a tilt angle increasing linearly with the distance between the scan lines, except for the region close to the left boundary of the scanned area, where the ripples are oriented at 90 degrees. This region can penetrate considerably to the right, forming a complex branched pattern. These predictions are substantiated by atomic force microscopy nanolithography experiments on polystyrene surfaces at room temperature. A simple and robust theoretical protocol for reproducing early-stage wear processes (potentially going beyond single contacts) is thus made available.

  • 295.
    McCarrick, Sarah
    et al.
    Karolinska Inst, Inst Environm Med, S-17177 Stockholm, Sweden..
    Wei, Zheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Moelijker, Nynke
    Toxys, Leiden, Netherlands..
    Derr, Remco
    Toxys, Leiden, Netherlands..
    Persson, Kjell-Arne
    Swerim AB, Lulea, Sweden..
    Hendriks, Giel
    Toxys, Leiden, Netherlands..
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Karlsson, Hanna L.
    Karolinska Inst, Inst Environm Med, S-17177 Stockholm, Sweden..
    High variability in toxicity of welding fume nanoparticles from stainless steel in lung cells and reporter cell lines: the role of particle reactivity and solubility2019In: Nanotoxicology, ISSN 1743-5390, E-ISSN 1743-5404Article in journal (Refereed)
    Abstract [en]

    Millions of people in the world perform welding as their primary occupation resulting in exposure to metal-containing nanoparticles in the fumes generated. Even though health effects including airway diseases are well-known, there is currently a lack of studies investigating how different welding set-ups and conditions affect the toxicity of generated nanoparticles of the welding fume. The aim of this study was to investigate the toxicity of nine types of welding fume particles generated via active gas shielded metal arc welding (GMAW) of chromium-containing stainless steel under different conditions and, furthermore, to correlate the toxicity to the particle characteristics. Toxicological endpoints investigated were generation of reactive oxygen species (ROS), cytotoxicity, genotoxicity and activation of ToxTracker reporter cell lines. The results clearly underline that the choice of filler material has a large influence on the toxic potential. Fume particles generated by welding with the tested flux-cored wire (FCW) were found to be more cytotoxic compared to particles generated by welding with solid wire or metal-cored wire (MCW). FCW fume particles were also the most potent in causing ROS and DNA damage and they furthermore activated reporters related to DNA double- strand breaks and p53 signaling. Interestingly, the FCW fume particles were the most soluble in PBS, releasing more chromium in the hexavalent form and manganese compared to the other fumes. These results emphasize the importance of solubility of different metal constituents of the fume particles, rather than the total metal content, for their acute toxic potential.

  • 296.
    McCracken, Joselle M.
    et al.
    Univ Illinois, Dept Chem, 600 S Matthews Ave, Urbana, IL 61801 USA..
    Rauzan, Brittany M.
    Univ Illinois, Dept Chem, 600 S Matthews Ave, Urbana, IL 61801 USA..
    Kjellman, Jacob C. E.
    Univ Illinois, Dept Chem, 600 S Matthews Ave, Urbana, IL 61801 USA..
    Su, Hanxiao
    Univ Illinois, Frederick Seitz Mat Res Lab, 1304 West Green St, Urbana, IL 61801 USA.;Univ Illinois, Dept Mat Sci & Engn, 1304 West Green St, Urbana, IL 61801 USA..
    Rogers, Simon A.
    Univ Illinois, Dept Chem & Biomol Engn, 600 S Matthews Ave, Urbana, IL 61801 USA..
    Nuzzo, Ralph G.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Univ Illinois, Dept Chem, 600 S Matthews Ave, Urbana, IL 61801 USA.;Univ Illinois, Frederick Seitz Mat Res Lab, 1304 West Green St, Urbana, IL 61801 USA.;Univ Illinois, Dept Mat Sci & Engn, 1304 West Green St, Urbana, IL 61801 USA.;KTH Royal Inst Technol, Surface & Corros Sci, Sch Engn Sci Chem Biotechnol & Hlth, Drottning Kristinasvag 51, S-10044 Stockholm, Sweden..
    Ionic Hydrogels with Biomimetic 4D-Printed Mechanical Gradients: Models for Soft-Bodied Aquatic Organisms2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 28, article id 1806723Article in journal (Refereed)
    Abstract [en]

    Direct-ink writing (DIW), a rapidly growing and advancing form of additive manufacturing, provides capacities for on-demand tailoring of materials to meet specific requirements for final designs. The penultimate challenge faced with the increasing demand of customization is to extend beyond modification of shape to create 4D structures, dynamic 3D structures that can respond to stimuli in the local environment. Patterning material gradients is foundational for assembly of 4D structures, however, there remains a general need for useful materials chemistries to generate gray scale gradients via DIW. Here, presented is a simple materials assembly paradigm using DIW to pattern ionotropic gradients in hydrogels. Using structures that architecturally mimic sea-jelly organisms, the capabilities of spatial patterning are highlighted as exemplified by selectively programming the valency of the ion-binding agents. Spatial gradients, when combined with geometry, allow for programming the flexibility and movement of iron oxide nanoparticle-loaded ionotropic hydrogels to generate 4D-printed structures that actuate in the presence of local magnetic fields. This work highlights approaches to 4D design complexity that exploits 3D-printed gray-scale/gradient mechanics.

  • 297.
    McKee, Lauren S.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Martinez-Abad, Antonio
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Ruthes, Andrea C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. AlbaNova Univ Ctr, KTH Royal Inst .
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Brumer, Harry
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Focused Metabolism of beta-Glucans by the Soil Bacteroidetes Species Chitinophaga pinensis2019In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 85, no 2, article id UNSP e02231-18Article in journal (Refereed)
    Abstract [en]

    The genome and natural habitat of Chitinophaga pinensis suggest it has the ability to degrade a wide variety of carbohydrate-based biomass. Complementing our earlier investigations into the hydrolysis of some plant polysaccharides, we now show that C. pinensis can grow directly on spruce wood and on the fungal fruiting body. Growth was stronger on fungal material, although secreted enzyme activity was high in both cases, and all biomass-induced secretomes showed a predominance of beta-glucanase activities. We therefore conducted a screen for growth on and hydrolysis of beta-glucans isolated from different sources. Most noncrystalline beta-glucans supported good growth, with variable efficiencies of polysaccharide deconstruction and oligosaccharide uptake, depending on the polysaccharide backbone linkage. In all cases, beta-glucan was the only type of polysaccharide that was effectively hydrolyzed by secreted enzymes. This contrasts with the secretion of enzymes with a broad range of activities observed during growth on complex heteroglycans. Our findings imply a role for C. pinensis in the turnover of multiple types of biomass and suggest that the species may have two metabolic modes: a "scavenging mode," where multiple different types of glycan may be degraded, and a more "focused mode" of beta-glucan metabolism. The significant accumulation of some types of beta-gluco-oligosaccharides in growth media may be due to the lack of an appropriate transport mechanism, and we propose that this is due to the specificity of expressed polysaccharide utilization loci. We present a hypothetical model for beta-glucan metabolism by C. pinensis that suggests the potential for nutrient sharing among the microbial litter community. IMPORTANCE It is well known that the forest litter layer is inhabited by a complex microbial community of bacteria and fungi. However, while the importance of fungi in the turnover of natural biomass is well established, the role of their bacterial counterparts is less extensively studied. We show that Chitinophaga pinensis, a prominent member of an important bacterial genus, is capable of using both plant and fungal biomass as a nutrient source but is particularly effective at deconstructing dead fungal material. The turnover of dead fungus is key in natural elemental cycles in the forest. We show that C. pinensis can perform extensive degradation of this material to support its own growth while also releasing sugars that may serve as nutrients for other microbial species. Our work adds detail to an increasingly complex picture of life among the environmental microbiota.

  • 298.
    Mei, Nanxuan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hedberg, Jonas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Blomberg, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Division Bioscience and Materials, RISE Research Institutes of Sweden, Stockholm, 111 21, Sweden.
    Influence of Biocorona Formation on the Transformation and Dissolution of Cobalt Nanoparticles under Physiological Conditions2019In: ACS Omega, ISSN 2470-1343, Vol. 4, no 26, p. 21778-21791Article in journal (Refereed)
    Abstract [en]

    Cobalt (Co) nanoparticles (NPs) are produced in different applications and unintentionally generated at several occupational and traffic settings. Their diffuse dispersion may lead to interactions with humans and aquatic organisms via different exposure routes that include their transformation/dissolution in biological media. This paper has investigated the particle stability and reactivity of Co NPs (dispersed by sonication prior to exposure) interacting with selected individual biomolecules (amino acids, polypeptides, and proteins) in phosphate-buffered saline (PBS). No or minor adsorption of amino acids (glutamine, glutamic acid, lysine, and cysteine) was observed on the Co NPs, independent of the functional group and charge. Instead, phosphate adsorption resulted in the formation of a surface layer (a corona) of Co phosphate. The adsorption of larger biomolecules (polyglutamic acid, polylysine, lysozyme, and mucin) was evident in parallel with the formation of Co phosphate. The dissolution of the Co NPs was rapid as 35-55% of the particle mass was dissolved within the first hour of exposure. The larger biomolecules suppressed the dissolution initially compared to exposure in PBS only, whereas the dissolution was essentially unaffected by the presence of amino acids, with cysteine as an exception. The formation of Co phosphate on the NP surface reduced the protective properties of the surface oxide of the Co NPs, as seen from the increased levels of the released Co when compared with the nonphosphate-containing saline. The results underline the diversity of possible outcomes with respect to surface characteristics and dissolution of Co NPs in biological media and emphasize the importance of surface interactions with phosphate on the NP characteristics and reactivity.

  • 299.
    Menzel, Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. Univ Politecn Valencia, Inst Ingn Alimentos Desarrolla, Dept Tecnol Alimentos, Valencia, Spain..
    Gonzalez-Martinez, Chelo
    Univ Politecn Valencia, Inst Ingn Alimentos Desarrolla, Dept Tecnol Alimentos, Valencia, Spain..
    Chiralt, Amparo
    Univ Politecn Valencia, Inst Ingn Alimentos Desarrolla, Dept Tecnol Alimentos, Valencia, Spain..
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Antioxidant starch films containing sunflower hull extracts2019In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 214, p. 142-151Article in journal (Refereed)
    Abstract [en]

    This study explores the preparation of antioxidant starch food packaging materials by the incorporation of valuable phenolic compounds extracted from sunflower hulls, which are an abundant by-product from food industry. The phenolic compounds were extracted with aqueous methanol and embedded into starch films. Their effect on starch films was investigated in terms of antioxidant activity, optical, thermal, mechanical, barrier properties and changes in starch molecular structure. The starch molecular structure was affected during thermal processing resulting in a decrease in molar mass, smaller amylopectin molecules and shorter amylose branches. Already 1-2% of extracts were sufficient to produce starch films with high antioxidant capacity. Higher amounts (4-6%) of extract showed the highest antioxidant activity, the lowest oxygen permeability and high stiffness and poor extensibility. The phenolic extracts affected predominantly the mechanical properties, whereas other changes could mainly be correlated to the lower glycerol content which was partially substituted by the extract.

  • 300.
    Meyer, Gerd
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Small cause - Great effect: What the 4f(n+1)5d(0) -> 4f(n)5d(1) configuration crossover does to the chemistry of divalent rare-earth halides and coordination compounds2019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 270, p. 324-334Article in journal (Refereed)
    Abstract [en]

    The rare-earth elements in the divalent state, i.e. with oxidation number + 2, may either have the electron configuration 4f(n+1)5d degrees(symbolized as R2+) or 4f(n)5d(1) (R(3+)e(-)). As R2+ (R = Eu, Yb, Sm, Tm, Dy, Nd) they can either be contained in extended solids as in the insulating diiodides RI2, or in coordination complexes such as samarocene, Kagan's reagent, or TmI2(DME)(3). In the case of R(3+)e(-), the "excess" d electron can either be delocalized and cause (semi)metallic behavior in extended solids, e.g. in LaI2, or localized with the R(3+)e(-) = 4f(n)5d(1) ion trapped in a coordination complex with (super)bulky ligands such as in [K(2.2.2-crypt)][LaCp ''(3)]. Thus, the seemingly small cause of a one-electron configuration crossover, 4f(n+1)5d degrees <--> Hf(n)5d(1) has a large effect on the chemical behavior and physical properties of the respective compounds where atomic properties and ligand effects play important roles.

3456789 251 - 300 of 531
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf