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  • 151. Janosik, T.
    et al.
    Rannug, A.
    Rannug, U.
    Wahlström, N.
    Slätt, Johnny
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Bergman, J.
    Chemistry and Properties of Indolocarbazoles2018Inngår i: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 118, nr 18, s. 9058-9128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The indolocarbazoles are an important class of nitrogen heterocycles which has evolved significantly in recent years, with numerous studies focusing on their diverse biological effects, or targeting new materials with potential applications in organic electronics. This review aims at providing a broad survey of the chemistry and properties of indolocarbazoles from an interdisciplinary point of view, with particular emphasis on practical synthetic aspects, as well as certain topics which have not been previously accounted for in detail, such as the occurrence, formation, biological activities, and metabolism of indolo[3,2-b]carbazoles. The literature of the past decade forms the basis of the text, which is further supplemented with older key references.

  • 152.
    Jiang, Xiaoqing
    et al.
    Dalian Univ Technol, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Wang, Dongping
    Dalian Univ Technol, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China.;Shenyang Univ Chem Technol, Coll Chem Engn, Shenyang 110142, Liaoning, Peoples R China..
    Yu, Ze
    Dalian Univ Technol, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Ma, Wanying
    Shenyang Univ Chem Technol, Coll Chem Engn, Shenyang 110142, Liaoning, Peoples R China..
    Li, Hai-Bei
    Shandong Univ, Sch Ocean, Weihai 264209, Peoples R China..
    Yang, Xichuan
    Dalian Univ Technol, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Liu, Feng
    Shanghai Jiao Tong Univ, Dept Phys, Shanghai 200240, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Molecular Engineering of Copper Phthalocyanines: A Strategy in Developing Dopant-Free Hole-Transporting Materials for Efficient and Ambient-Stable Perovskite Solar Cells2019Inngår i: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 9, nr 4, artikkel-id 1803287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Copper (II) phthalocyanines (CuPcs) have attracted growing interest as promising hole-transporting materials (HTMs) in perovskite solar cells (PSCs) due to their low-cost and excellent stability. However, the most efficient PSCs using CuPc-based HTMs reported thus far still rely on hygroscopic p-type dopants, which notoriously deteriorate device stability. Herein, two new CuPc derivatives are designed, namely CuPc-Bu and CuPc-OBu, by molecular engineering of the non-peripheral substituents of the Pc rings, and applied as dopant-free HTMs in PSCs. Remarkably, a small structural change from butyl groups to butoxy groups in the substituents of the Pc rings significantly influences the molecular ordering and effectively improves the hole mobility and solar cell performance. As a consequence, PSCs based on dopant-free CuPc-OBu as HTMs deliver an impressive power conversion efficiency (PCE) of up to 17.6% under one sun illumination, which is considerably higher than that of devices with CuPc-Bu (14.3%). Moreover, PSCs containing dopant-free CuPc-OBu HTMs show a markedly improved ambient stability when stored without encapsulation under ambient conditions with a relative humidity of 85% compared to devices containing doped Spiro-OMeTAD. This work thus provides a fundamental strategy for the future design of cost-effective and stable HTMs for PSCs and other optoelectronic devices.

  • 153. Jin, Ying
    et al.
    Lai, Zhaogui
    Bi, Peng
    Yan, Songtao
    Wen, Lei
    Wang, Yongchao
    Pan, Jinshan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Combining lithography and capillary techniques for local electrochemical property measurements2018Inngår i: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 87, s. 53-57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The relationships between composition, microstructure and electrochemical properties are of fundamental importance in understanding the corrosion of multiphase materials and thus in aiding in the design of new materials. A local electrochemical test system which combines a capillary device with a photolithographic mask has been developed to investigate the local electrochemical properties of a predefined micron-sized area with greater reliability and versatility than existing approaches. Independent electrochemical measurements were conducted on the different phases of a 2205 duplex stainless steel in NaCl solution, demonstrating the feasibility of the developed test system.

  • 154.
    Johansson, F. O. L.
    et al.
    Uppsala Univ, Dept Phys & Astron, Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Ivanovic, M.
    Univ Tubingen, Inst Phys & Theoret Chem, Morgenstelle 18, D-72076 Tubingen, Germany..
    Svanstrom, S.
    Uppsala Univ, Dept Phys & Astron, Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Cappel, Ute B.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. Uppsala Univ, Dept Phys & Astron, Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden.
    Peisert, H.
    Univ Tubingen, Inst Phys & Theoret Chem, Morgenstelle 18, D-72076 Tubingen, Germany..
    Chasse, T.
    Univ Tubingen, Inst Phys & Theoret Chem, Morgenstelle 18, D-72076 Tubingen, Germany..
    Lindblad, A.
    Uppsala Univ, Dept Phys & Astron, Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Femtosecond and Attosecond Electron-Transfer Dynamics in PCPDTBT:PCBM Bulk Heterojunctions2018Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, nr 24, s. 12605-12614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Charge separation efficiency is a crucial parameter for photovoltaic devices-polymers consisting of alternating electron-rich and electron-deficient parts can achieve high such efficiencies, for instance, together with a fullerene electron acceptor. This offers a viable path toward solar cells with organic bulk heterojunctions. Here, we measured the charge-transfer times in the femtosecond and attosecond regimes via the decay of sulfur is X-ray core excited states (with the core-hole clock method) in blends of a low-band gap polymer {PCPDTBT [poly[2,6-(4,4-bis (2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-1/1 dithiophene)-alt-4,7- (2,1,3-benzothiadiazole)]]} consisting of a cyclopentadithiophene electron-rich part and a benzothiadiazole electron-deficient part. The constituting parts of the bulk heterojunction were varied by adding the fullerene derivative PCBM ([6,6]-phenyl-C-61-butyric acid methyl ester) (weight ratio of polymer/PCBM as 1:0, 1:1, 1:2, and 1:3). For low-energy excitations, the charge-transfer time varies to the largest extent for the thiophene donor part. The charge-transfer time in the 1:2 blend is reduced by 86% compared to that of pristine PCPDTBT. At higher energy excitations, the charge-transfer time does not vary with the chemical environment, as this regime is dominated by intramolecular conduction that yields ultrafast charge-transfer times for all blends, approaching 170 as. We thus demonstrate that the core-hole clock method applied to a series with changing composition can give information about local electron dynamics (with chemical specificity) at interfaces between the constituting parts the crucial part of a bulk heterojunction where the initial charge separation occurs.

  • 155.
    Josefsson, Leila
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Cronhamn, Melker
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Ekman, Malin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Widehammar, Hugo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Emmer, Åsa
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Structural basis for the formation of soy protein nanofibrils2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 11, s. 6310-6319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Amyloid-like protein nanofibrils (PNFs) can assemble from a range of different proteins including disease-associated proteins, functional amyloid proteins and several proteins for which the PNFs are neither related to disease nor function. We here examined the core building blocks of PNFs formed by soy proteins. Fibril formation at pH 2 and 90 degrees C is coupled to peptide hydrolysis which allows isolation of the PNF-forming peptides and identification of them by mass spectrometry. We found five peptides that constitute the main building blocks in soy PNFs, three of them from the protein b-conglycinin and two from the protein glycinin. The abilities of these peptides to form PNFs were addressed by amyloid prediction software and by PNF formation of the corresponding synthetic peptides. Analysis of the structural context in the native soy proteins revealed two structural motifs for the PNF-forming peptides: (i) so-called b-arches and (ii) helical segments involved in quaternary structure contacts. However, the results suggest that neither the native structural motifs nor the protein of origin defines the morphology of the PNFs formed from soy protein isolate.

  • 156.
    Josefsson, Leila
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Emmer, Åsa
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Imaging of polyvinyl alcohol microbubbles in a capillary using a homebuilt microscopeManuskript (preprint) (Annet (populærvitenskap, debatt, mm))
  • 157.
    Josefsson, Leila
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Goodall, David
    Emmer, Åsa
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Implementation of a UV area imaging detector for analysis of polyvinyl alcohol microbubbles in capillary electrophoresisManuskript (preprint) (Annet vitenskapelig)
  • 158.
    Josefsson, Leila
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Xinchen, Ye
    Brett, Calvin
    Meijer, Jonas
    Olsson, Carl
    Sjögren, Amanda
    Sundlöf, Josefin
    Davydok, Anton
    Langton, Maud
    Emmer, Åsa
    Lendel, Christofer
    Protein nanofibrils from potato protein isolate - preparation and characterizationManuskript (preprint) (Annet vitenskapelig)
  • 159.
    Judith Cruz, M.
    et al.
    Univ Antofagasta, Dept Chem Engn & Mineral Proc, Antofagasta, Chile.;Univ Antofagasta, Ctr Adv Study Lithium & Ind Minerals CELiMIN, Antofagasta, Chile..
    Makarova, Irina V.
    Belarusian State Technol Univ, Dept Chem Technol Electrochem Prod & Elect Engn M, Minsk, BELARUS.;Lappeenranta Univ Technol, Sch Engn Sci, Dept Separat & Purificat, Skinnarilankatu 34, FI-53850 Lappeenranta, Finland..
    Kharitonov, Dmitry S.
    Belarusian State Technol Univ, Dept Chem Technol Electrochem Prod & Elect Engn M, Minsk, BELARUS.;Polish Acad Sci, Jerzy Haber Inst Catalysis & Surface Chem, Krakow, Poland..
    Dobryden, Illia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Chernik, Alexander A.
    Belarusian State Technol Univ, Dept Chem Technol Electrochem Prod & Elect Engn M, Minsk, BELARUS..
    Grageda, Mario
    Univ Antofagasta, Dept Chem Engn & Mineral Proc, Antofagasta, Chile.;Univ Antofagasta, Ctr Adv Study Lithium & Ind Minerals CELiMIN, Antofagasta, Chile..
    Ushak, Svetlana
    Univ Antofagasta, Dept Chem Engn & Mineral Proc, Antofagasta, Chile.;Univ Antofagasta, Ctr Adv Study Lithium & Ind Minerals CELiMIN, Antofagasta, Chile..
    Corrosion properties of nickel coatings obtained from aqueous and nonaqueous electrolytes2019Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 51, nr 9, s. 943-953Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nickel was deposited on a copper substrate from aqueous and nonaqueous ethanol electrolytes. X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and chronovoltametry, scanning electron microscopy, and atomic force microscopy were used to study the effect of the solvent on the surface and corrosion properties of the Ni coatings formed. Unifom and relatively smooth Ni films were obtained as measured with microscopy techniques. The formation of a passive film in acidic, alkaline, and neutral chloride-containing media was confirmed with X-ray photoelectron spectroscopy. The water-based nickel-plating electrolyte makes it possible to deposit coatings with higher corrosion resistance as compared with coatings deposited from ethanol electrolyte in NaOH and NaCl media. The proposed mechanism of corrosion in a 0.5 M H2SO4 solution involves cycles of active-passive surface behavior due to its passivation by corrosion products.

  • 160.
    Kaestner, Bernd
    et al.
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Johnson, C. Magnus
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Hermann, Peter
    PTB, Abbestr 2-12, D-10587 Berlin, Germany.;Deutschland GmbH & Co KG, West Pharmaceut Serv, Stolberger Str 21-41, D-52249 Eschweiler, Germany..
    Kruskopf, Mattias
    PTB, Bundesallee 100, D-38116 Braunschweig, Germany.;NIST, 100 Bur Dr, Gaithersburg, MD 20899 USA..
    Pierz, Klaus
    PTB, Bundesallee 100, D-38116 Braunschweig, Germany..
    Hoehl, Arne
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Hornemann, Andrea
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Ulrich, Georg
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Fehmel, Jakob
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Patoka, Piotr
    Free Univ Berlin, Inst Chem & Biochem, Phys Chem, Takustr 3, D-14195 Berlin, Germany..
    Ruehl, Eckart
    Free Univ Berlin, Inst Chem & Biochem, Phys Chem, Takustr 3, D-14195 Berlin, Germany..
    Ulm, Gerhard
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Infrared Nanospectroscopy of Phospholipid and Surfactin Monolayer Domains2018Inngår i: ACS OMEGA, ISSN 2470-1343, Vol. 3, nr 4, s. 4141-4147Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A main challenge in understanding the structure of a cell membrane and its interactions with drugs is the ability to chemically study the different molecular species on the nanoscale. We have achieved this for a model system consisting of mixed monolayers (MLs) of the biologically relevant phospholipid 1,2-distearoyl-sn-glycero-phosphatidylcholine and the antibiotic surfactin. By employing nano-infrared (IR) microscopy and spectroscopy in combination with atomic force microscopy imaging, it was possible to identify and chemically detect domain formation of the two constituents as well as to obtain IR spectra of these species with a spatial resolution on the nanoscale. A novel method to enhance the near-field imaging contrast of organic MLs by plasmon interferometry is proposed and demonstrated. In this technique, the organic layer is deposited on gold and ML graphene substrates, the latter of which supports propagating surface plasmons. Plasmon reflections arising from changes in the dielectric environment provided by the organic layer lead to an additional contrast mechanism. Using this approach, the interfacial region between surfactin and the phospholipid has been mapped and a transition region is identified.

  • 161.
    Kamada, Ayaka
    et al.
    Univ Tokyo, Dept Bioengn, Tokyo, Japan..
    Mittal, Nitesh
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Assembly mechanism of nanostructured whey protein filaments2016Inngår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 252Artikkel i tidsskrift (Annet vitenskapelig)
  • 162.
    Kanerva, M.
    et al.
    Tampere Univ, Fac Engn & Nat Sci, POB 589, FI-33014 Tampere, Finland.;Orton Orthopaed Hosp, FI-00280 Helsinki, Finland.;Res Inst Orton, FI-00280 Helsinki, Finland..
    Besharat, Zahra
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Parnanen, T.
    Orton Orthopaed Hosp, FI-00280 Helsinki, Finland.;Res Inst Orton, FI-00280 Helsinki, Finland..
    Jokinen, J.
    Tampere Univ, Fac Engn & Nat Sci, POB 589, FI-33014 Tampere, Finland..
    Honkanen, M.
    Tampere Univ, Fac Engn & Nat Sci, POB 589, FI-33014 Tampere, Finland..
    Sarlin, E.
    Tampere Univ, Fac Engn & Nat Sci, POB 589, FI-33014 Tampere, Finland..
    Göthelid, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Schlenzka, D.
    Orton Orthopaed Hosp, FI-00280 Helsinki, Finland.;Res Inst Orton, FI-00280 Helsinki, Finland..
    Miniature CoCr laser welds under cyclic shear: Fatigue evolution and crack growth2019Inngår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 99, s. 93-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Miniature laser welds with the root depth in the range of 50-300 pm represent air-tight joints between the components in medical devices, such as those in implants, growth rods, stents and various prostheses. The current work focuses on the development of a fatigue test specimen and procedure to determine fatigue lives of shear-loaded laser welds. A cobalt-chromium (CoCr) alloy is used as a benchmark case. S-N graphs, damage process, and fracture surfaces are studied by applying x-ray analysis, atomic force microscopy, and scanning electron microscopy both before and after the crack onset. A non-linear material model is fitted for the CoCr alloy to run finite element simulations of the damage and deformation. As a result, two tensile-loaded specimen designs are established and the performance is compared to that of a traditional torque-loaded specimen. The new generation specimens show less variation in the determined fatigue lives due to well-defined crack onset point and, therefore, precise weld seam load during the experiments. The fatigue damage concentrates to the welded material and the entire weld experiences fatigue prior to the final, fracture-governed failure phase. For the studied weld seams of hardened CoCr, a regression fatigue limit of 10.8-11.8 MPa, where the stress refers to the arithmetic average shear stress computed along the region dominated by shear loading, is determined.

  • 163.
    Kanninen, Petri
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Eriksson, Björn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Davodi, Fatemeh
    Aalto University.
    Buan, Marthe
    Aalto University.
    Kallio, Tanja
    Aalto University.
    Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Carbon corrosion properties and performance of multi-walled carbon nanotube support with and without nitrogen-functionalization in fuel cell electrodesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Pt-supported on multi-walled carbon nanotubes (MWCNT) and N-modified MWCNT (N-MWCNT) catalysts are synthesized by pyrolysis from emeraldine solution and microemulsion. Their electrochemical properties and carbon corrosion resistance in a Proton Exchange Membrane Fuel Cell (PEMFC) are compared with a commercial Pt/Vulcan catalyst through I-V curves, cyclic voltammetry and CO stripping. The initial fuel cell performances of the Pt/(N-)MWCNT catalysts are superior to Pt/Vulcan. The corrosion of the catalysts is quantified by the continuous measure of the CO2 release by online-mass spectrometry during potentiodynamic cycling between 0.1 and 1.6 V at 80°C. The results show that Pt/MWCNT (with the lowest double-layer capacity) is the most stable catalyst followed by Pt/N-MWCNT and Pt/Vulcan, initially losing carbon at a rate of 1.1, 3.4 and 4.7 µgC (mg Ctot)−1 cycle−1 , respectively. After about 30 % carbon loss (50-70 cycles) all catalysts corrode at an approximate rate of 5.5 µgC mg−1 cycle−1. At this stage, all show similar electrochemical surface area and double-layer capacity. However, the substantial diminution of the initially very thick and porous Pt/(N-)MWCNT catalyst layers after corrosion consequences in lower fuel cell performance compared to the structurally less affected Pt/Vulcan electrode. The results clearly reveal that CNT-based catalyst supports are more corrosion resistant compared to state-of-the-art Vulcan. Moreover, the performance of the corroded electrodes envisages the importance of electrode porosity. 

  • 164. Kaur, S.
    et al.
    Srivastava, A.
    Kumar, Sanjiv
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Srivastava, Vaibhav
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Ahluwalia, A. S.
    Mishra, Y.
    Biochemical and proteomic analysis reveals oxidative stress tolerance strategies of Scenedesmus abundans against allelochemicals released by Microcystis aeruginosa2019Inngår i: Algal Research, ISSN 2211-9264, Vol. 41, artikkel-id 101525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We studied the possible survival strategies of a green alga, Scenedesmus abundans, against allelochemicals secreted by Microcystis aeruginosa. We exposed the monoculture of S. abundans to a cell free-filtrate (allelochemicals)of M. aeruginosa at the start of our experiment and measured the growth behaviour, morphological changes and oxidative stress markers. The results suggest that exposure to allelochemicals induced oxidative stress in S. abundans, which had significantly reduced the growth of green alga with certain morphological changes. However, after seven days, S. abundans found ways to reduce oxidative stress by recovering its morphology and growth close to that of control. To understand possible survival strategies of test alga, we measured biochemical as well as protein level changes in S. abundans. Biochemical response of the green alga clearly showed that as a response to allelochemicals, enzymatic and non-enzymatic antioxidants were induced. Proteomic analysis showed that exposure to allelochemicals induced accumulation of 13 proteins on the 2-DE gel of S. abundans, which falls in three functional categories, i.e., (i)energy metabolism (photosynthesis, carbon fixation and respiration), (ii)ROS scavenging enzymes and molecular chaperones, and (iii)amino acid and protein biosynthesis. After chronic oxidative stress, these proteins presumably retained glycolysis, pentose phosphate pathway and turnover rate of the Calvin-Benson cycle. Moreover, these proteins assisted in the adequate detoxification of ROS and played an important role in the damage removal and repair of oxidized proteins, lipids and nucleic acids. Therefore, our study anticipates that S. abundans embraces biochemical and proteomic reprogramming to thrives against allelochemicals released by M. aeruginosa.

  • 165.
    Kawada, S.
    et al.
    Japan.
    Watanabe, Seiya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Sasaki, S.
    Japan.
    Miyatake, M.
    Japan.
    Evaluation of friction behavior and surface interactions of cyano-based ionic liquids under different sliding contacts and high vacuum condition2018Inngår i: Lubricants, ISSN 2075-4442, Vol. 6, nr 3, artikkel-id 69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The friction coefficients of ionic liquids were evaluated by many investigations. Most investigations used fluorine-based ionic liquids as lubricants. However, these ionic liquids produce the corrosion wear. This investigation focuses on the use of cyano-based ionic liquids as lubricants. Compared to fluorine-based ionic liquids, cyano-based ionic liquids exhibit high friction coefficients against steel material. This work examines how the friction coefficients of cyano-based ionic liquids are influenced by the type of sliding material used (AISI 52100, TiO2, and tetrahedral amorphous carbon). TiO2 lubricated with 1-ethyl-3-methylimidazolium tricyanomethanide, and ta-C lubricated with 1-butyl-1methylpyrrolidinium tetracyanoborate exhibited very low friction coefficients, smaller than fluorine-based ionic liquids. Time-of-Flight Secondary Ion Mass Spectrometry analysis showed that anions adsorb onto the worn surface, suggesting that anion adsorption is a critical parameter influencing friction coefficients. Quadrupole Mass Spectrometry measurements revealed that cations decompose on the nascent surface, preventing adsorption on the worn surface. These results suggest that low friction coefficients require the decomposition of cations and adsorption of anions. The reactivity of nascent surface changes with the sliding material used due to varying catalytic activity of the nascent surfaces.

  • 166. Kawada, S.
    et al.
    Watanabe, Seiya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Tadokoro, C.
    Sasaki, S.
    Effects of Alkyl Chain Length of Sulfate and Phosphate Anion-Based Ionic Liquids on Tribochemical Reactions2018Inngår i: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, nr 1, artikkel-id 8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ionic liquids are expected to become increasingly popular lubricants as they feature a number of attractive properties. This investigation focused on sulfate and phosphate anion-based ionic liquids and the improvement in lubricating performance with the addition of these anions. However, the detailed lubricating mechanism and effect of alkyl chain length on tribochemical reactions are unclear. This study investigates tribochemical reaction processes using a quadrupole mass spectrometer (Q-MS) and X-ray photoelectron spectroscopy. Seven types of ionic liquids: 1-ethyl-3-methylimidazolium hydrogensulfate ([EMIM][HSO4]), 1-ethyl-3-methylimidazolium methylsulfate ([EMIM][MSU]), 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESU]), 1-ethyl-3-methylimidazolium n-octylsulfate ([EMIM][OSU]), 1-ethyl-3-methylimidazolium dimethyl phosphate ([EMIM][DMP]), 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]), and 1-ethyl-3-methylimidazolium dibutyl phosphate ([EMIM][DBP]), were selected as lubricants. The friction coefficient of sulfate anion-based ionic liquids increased as their alkyl chain lengthened. However, wear scar diameter in this case showed the opposite tendency. The friction coefficient and wear scar diameter of phosphate anion-based ionic liquids increased with an increase in the alkyl chain length. Q-MS results indicated that the main outgassing components during sliding were the cation components, whereas the anion remained on the sliding surface and formed a tribofilm. The ionic liquids with short alkyl chains reacted with the sliding surface easily and led to very low friction. However, corrosive wear occurred in the case of the sulfate anion. On the other hand, anions with long alkyl chains underwent gradual tribochemical reactions because that led the mitigation of contact with nascent surface. The phosphate-based ionic liquids with long alkyl chains were unable to cause the lubricating effect due to low reactivity.

  • 167. Kawada, S.
    et al.
    Watanabe, Seiya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Tadokoro, C.
    Tsuboi, R.
    Sasaki, S.
    Lubricating mechanism of cyano-based ionic liquids on nascent steel surface2018Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 119, s. 474-480Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the lubricating mechanism of cyano-based ionic liquids on steel surfaces using Q-MS, ToF-SIMS, and TGA. [EMIM][DCN], [EMIM][TCC], [EMIM][TCB], [BMPL][DCN], [BMPL][TCC], and [BMPL][TCB] were selected as lubricants. [EMIM][TCB] exhibited the highest friction coefficient. The others exhibited very low friction coefficients of less than 0.08. Q-MS analysis indicated that the cation components were detected in outgassing during sliding tests. However, anion components were not detected. ToF-SIMS results showed that the anions remained on the worn surfaces which would lead low friction coefficients. To achieve low friction coefficient, the tribo-decomposition of the ionic liquids and adsorption of anion were required. TGA indicated thermal stability was an index for tribo-decomposition on the nascent steel surface.

  • 168. Kawada, Shouhei
    et al.
    Sato, Keisuke
    Watanabe, Seiya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Sasaki, Shinya
    Lubricating property of cyano-based ionic liquids against hard materials2017Inngår i: Journal of Mechanical Science and Technology, ISSN 1738-494X, E-ISSN 1976-3824, Vol. 31, nr 12, s. 5745-5750Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ionic liquids are expected to be used as a new lubricants and lubricant additives because of their unique properties. However, cyano-based ionic liquids have exhibited poor lubricating property with steel/steel contacts. We evaluated the lubricating properties of cyano-based ionic liquids with steel/hard materials contacts. TiO2, Al2O3, and tetrahedral amorphous carbon (ta-C) DLC were used as hard materials. Six types of ionic liquids, as combination of two types of cations ([EMIM], [BMPL]) and three types of cyanide anions ([DCN], [TCC] and [TCB]), were selected. In sliding tests of steel/TiO2 and steel/Al2O3 lubricated with [EMIM][DCN], [BMPL][DCN], [EMIM][TCC], [BMPL][TCC] exhibited low friction coefficients of less than 0.1. In addition, steel/Al2O3 and steel/ta-C DLC lubricated with [BMPL][TCB] exhibited very low friction coefficients less than 0.05. On the other hand, high friction coefficients were observed at steel/TiO2 and steel/Al2O3 contacts lubricated with [EMIM][TCB] and steel/ta-C DLC contact lubricated with [EMIM] cation group. Peeling of the ta-C DLC was observed when [EMIM] cation group was used. ToF-SIMS analysis indicated that the anion was adsorbed on the worn surfaces in the case of low frictional conditions. However, both ions were hardly observed in the case of high frictional conditions. It is considered that the ionic liquids underwent tribo-decomposition on the worn surfaces at low friction coefficient. To evaluate the degree of tribo-decomposition, Thermogravimetric analysis (TGA) was used. TGA results indicated that [EMIM][TCB], which exhibited high friction coefficient, had the most highest stability among all ionic liquids. Low stability ionic liquids, however, showed a tendency for low friction coefficient. These results suggest that lubricating properties are related to the stability of ionic liquids.

  • 169.
    Kharitonov, Dmitry S.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Sommertune, Jens
    RISE Res Inst Sweden, Surface Proc & Formulat, SE-11486 Stockholm, Sweden..
    Örnek, Cem
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Ryl, Jacek
    Gdansk Univ Technol, Dept Electrochem Corros & Mat Engn, 11-12 Narutowicza St, PL-80233 Gdansk, Poland..
    Kurilo, Irina I.
    Belarusian State Technol Univ, Organ Subst Technol Fac, Dept Phys Colloid & Analyt Chem, Minsk 220006, BELARUS..
    Claesson, Per M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Corrosion inhibition of aluminium alloy AA6063-T5 by vanadates: Local surface chemical events elucidated by confocal Raman micro-spectroscopy2019Inngår i: CORROSION SCIENCE, Vol. 148, s. 237-250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chemical interactions between aqueous vanadium species and aluminium alloy AA6063-T5 were investigated in vanadate-containing NaCl solutions. Confocal Raman and X-ray photoelectron spectroscopy experiments were utilised to gain insight into the mechanism of corrosion inhibition by vanadates. A greenish-grey coloured surface layer, consisting of V+4 and V+5 polymerized species, was seen to form on the alloy surface, especially on top of cathodic micrometre-sized IMPs, whereby suppressing oxygen reduction kinetics. The results suggest a two-step mechanism of corrosion inhibition in which V+5 species are first reduced to V+4 or V+3 species above cathodic IMPs, and then oxidized to mixed-valence V+5/V+4 polymerized compounds.

  • 170.
    Kharitonov, Dmitry S.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Electrochem Prod Technol & Mat Elect Eq, Minsk 220006, BELARUS..
    Örnek, Cem
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. Swerea KIMAB, Dept Corros Energy & Proc Ind, SE-16440 Kista, Sweden..
    Claesson, Per M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Sommertune, Jens
    RISE Res Inst Sweden, Chem Mat & Surfaces, SE-11486 Stockholm, Sweden..
    Zharskii, Ivan M.
    Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Electrochem Prod Technol & Mat Elect Eq, Minsk 220006, BELARUS..
    Kurilo, Irina I.
    Belarusian State Technol Univ, Organ Subst Technol Fac, Dept Phys Colloid & Analyt Chem, Minsk 220006, BELARUS..
    Pan, Jinshan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Corrosion Inhibition of Aluminum Alloy AA6063-T5 by Vanadates: Microstructure Characterization and Corrosion Analysis2018Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, nr 3, s. C116-C126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Corrosion inhibition of aluminum alloy AA6063-T5 by vanadates (NaVO3) in 0.05 M NaCl solution has been investigated by electrochemical and weight loss measurements, and associated with microstructure and Volta potential data. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses confirmed the presence of micrometer-sized Fe-rich Al4.01MnSi0.74, Al1.69Mg4Zn2.31, and FeAl3 intermetallic phases (IMPs) and nanometer-sized CuAl2, ZnAl2, and Mg2Si precipitates in the microstructure. Scanning Kelvin probe force microscopy measurements showed Volta potential differences of up to 600 mV between the microstructure constituents indicating a high susceptibility to micro-galvanic corrosion, with interphase boundary regions exhibiting the highest propensity to corrosion. Most IMPs had cathodic character whereas some nanometer-sized Mg-rich particles exhibited anodic nature, with large Volta potential gradients within interphase regions of large cathodic particles. Electrochemical potentiodynamic polarization measurements indicated that the vanadates provided mixed corrosion inhibition effects, mitigating both oxygen reduction, occurring on cathodic IMPs, and anodic metal dissolution reaction, occurring on anodic sites, such as Mg2Si and interphase boundary regions. Electrochemical measurements indicated that the sodium metavanadate inhibitor blocks active metal dissolution, giving high inhibition efficiency (>95%) during the initial exposure, whereas long-term weight loss measurements showed that the efficacy decreases after prolonged exposure.

  • 171.
    Kishani, Saina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH.
    Vilaplana, Francisco
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Solubility and adsorption of different xyloglucan fractions to model surfaces2018Inngår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikkel i tidsskrift (Annet vitenskapelig)
  • 172.
    Klinter, Stefan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Bulone, Vincent
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. Univ Adelaide, ARC Ctr Excellence Plant Cell Walls, Waite Campus, Urrbrae, SA 5064, Australia.;Univ Adelaide, Sch Agr Food & Wine, Waite Campus, Urrbrae, SA 5064, Australia..
    Arvestad, Lars
    Stockholm Univ, Dept Math, Swedish E Sci Res Ctr, Sci Life Lab, S-10691 Stockholm, Sweden..
    Diversity and evolution of chitin synthases in oomycetes (Straminipila: Oomycota)2019Inngår i: Molecular Phylogenetics and Evolution, ISSN 1055-7903, E-ISSN 1095-9513, Vol. 139, artikkel-id 106558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The oomycetes are filamentous eukaryotic microorganisms, distinct from true fungi, many of which act as crop or fish pathogens that cause devastating losses in agriculture and aquaculture. Chitin is present in all true fungi, but it occurs in only small amounts in some Saprolegniomycetes and it is absent in Peronosporomycetes. However, the growth of several oomycetes is severely impacted by competitive chitin synthase (CHS) inhibitors. Here, we shed light on the diversity, evolution and function of oomycete CHS proteins. We show by phylogenetic analysis of 93 putative CHSs from 48 highly diverse oomycetes, including the early diverging Ewychasma dicksonii, that all available oomycete genomes contain at least one putative CHS gene. All gene products contain conserved CHS motifs essential for enzymatic activity and form two Peronosporomycete-specific and six Saprolegniale-specific clades. Proteins of all clades, except one, contain an N-terminal microtubule interacting and trafficking (MIT) domain as predicted by protein domain databases or manual analysis, which is supported by homology modelling and comparison of conserved structural features from sequence logos. We identified at least three groups of CHSs conserved among all oomycete lineages and used phylogenetic reconciliation analysis to infer the dynamic evolution of CHSs in oomycetes. The evolutionary aspects of CHS diversity in modern-day oomycetes are discussed. In addition, we observed hyphal tip rupture in Phytophthora infestans upon treatment with the CHS inhibitor nikkomycin Z. Combining data on phylogeny, gene expression, and response to CHS inhibitors, we propose the association of different CHS clades with certain developmental stages.

  • 173. Kocabaş, M.
    et al.
    Örnek, Cem
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Curioni, M.
    Cansever, N.
    Nickel fluoride as a surface activation agent for electroless nickel coating of anodized AA1050 aluminum alloy2019Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 364, s. 231-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, the use of nickel fluoride tetrahydrate (NiF 2 ·4H 2 O) as a surface activator and sealant at the same time for the coating of electroless nickel-phosphorus (Ni-P) on anodized aluminum alloy AA1050 is proposed. The usage of the activator resulted in more efficient deposition of Ni-P, improved adhesion properties, and increased wear and friction behavior as opposed to non-activated conditions. Scanning electron microscopy (SEM) and confocal laser microscopy (CLM) analyses of ultramicrotome-cut cross sections of Ni-P coated specimens, surface-activated by NiF 2 ·4H 2 O, revealed a more well-structured metal-coating interface as opposed to non-activated conditions.

  • 174.
    Kong, Na
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Shimpi, Manishkumar R.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Park, Jaehyeung
    Univ Massachusetts, Dept Chem, Lowell, MA 01854 USA..
    Ramström, Olof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Yan, Mingdi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides (vol 405, pg 33, 2015)2015Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 412, s. 80-80Artikkel i tidsskrift (Fagfellevurdert)
  • 175.
    Kootala, Sujit
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Filho, L.
    Srivastava, Vaibhav
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Linderberg, Victoria
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Moussa, A.
    David, L.
    Trombotto, S.
    Crouzier, Thomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Reinforcing Mucus Barrier Properties with Low Molar Mass Chitosans2018Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 3, s. 872-882Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mucus gel covers the wet epithelia that forms the inner lining of the body. It constitutes our first line of defense protecting the body from infections and other deleterious molecules. Failure of the mucus barrier can lead to the inflammation of the mucosa such as in inflammatory bowel diseases. Unfortunately, there are no effective strategies that reinforce the mucus barrier properties to recover or enhance its ability to protect the epithelium. Herein, we describe a mucus engineering approach that addresses this issue where we physically cross-link the mucus gel with low molar mass chitosan variants to reinforce its barrier functions. We tested the effect of these chitosans on mucus using in-lab purified porcine gastric mucins, which mimic the native properties of mucus, and on mucus-secreting HT29-MTX epithelial cell cultures. We found that the lowest molar mass chitosan variant (degree of polymerization of 8) diffuses deep into the mucus gels while physically cross-linking the mucin polymers, whereas the higher molar mass chitosan variants (degree of polymerization of 52 and 100) interact only superficially. The complexation resulted in a tighter mucin polymer mesh that slowed the diffusion of dextran polymers and of the cholera toxin B subunit protein through the mucus gels. These results uncover a new use for low molar mass mucoadhesive polymers such as chitosans as noncytotoxic mucosal barrier enhancers that could be valuable in the prevention and treatment of mucosal diseases.

  • 176.
    Koppolu, Rajesh
    et al.
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland..
    Abitbol, Tiffany
    RISE Res Inst Sweden, Biosci & Mat Surface Proc & Formulat, S-11428 Stockholm, Sweden..
    Kumar, Vinay
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland.;Finland Ltd, VTT Tech Res Ctr, High Performance Fiber Prod, Espoo 02044, Finland..
    Jaiswal, Aayush Kumar
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland..
    Swerin, Agne
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. RISE Res Inst Sweden, Biosci & Mat Surface Proc & Formulat, S-11428 Stockholm, Sweden..
    Toivakka, Martti
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland..
    Continuous roll-to-roll coating of cellulose nanocrystals onto paperboard2018Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 10, s. 6055-6069Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is an increased interest in the use of cellulose nanocrystal (CNC) films and coatings for a range of functional applications in the fields of material science, biomedical engineering, and pharmaceutical sciences. Most of these applications have been demonstrated on films and coatings produced using laboratory-scale batch processes, such as solvent casting, dip coating, or spin coating. For successful coating application of CNC suspensions using a high throughput process, several challenges need to be addressed: relatively high viscosity at low solids content, coating brittleness, and potentially poor adhesion to the substrate. This work aims to address these problems. The impact of plasticizer on suspension rheology, coating adhesion, and barrier properties was quantified, and the effect of different pre-coatings on the wettability and adhesion of CNC coatings to paperboard substrates was explored. CNC suspensions were coated onto pre-coated paperboard in a roll-to-roll process using a custom-built slot die. The addition of sorbitol reduced the brittleness of the CNC coatings, and a thin cationic starch pre-coating improved their adhesion to the paperboard. The final coat weight, dry coating thickness, and coating line speed were varied between 1-11 g/m(2), 900 nm-7 A mu m, and 2.5-10 m/min, respectively. The barrier properties, adhesive strength, coating coverage, and smoothness of the CNC coatings were characterized. SEM images show full coating coverage at coat weights as low as 1.5 g/m(2). With sorbitol as plasticizer and at coat weights above 3.5 g/m(2), heptane vapor and water vapor transmission rates were reduced by as much as 99% and 75% respectively. Compared to other film casting techniques, the process employed in this work deposits a relatively thick coating in significantly less time, and may therefore pave the way toward various functional applications based on CNCs. [GRAPHICS] .

  • 177.
    Koppolu, Rajesh
    et al.
    Abo Akad Univ, Ctr Funct Mat, Lab Paper Coating & Converting, SF-20500 Turku, Finland..
    Lahti, Johanna
    Tampere Univ Technol, Paper Converting & Packaging, Tampere 33100, Finland..
    Abitbol, Tiffany
    RISE Res Inst Sweden, Bioecon Biorefinery & Energy, S-11428 Stockholm, Sweden..
    Swerin, Agne
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Kuusipalo, Jurkka
    Tampere Univ Technol, Paper Converting & Packaging, Tampere 33100, Finland..
    Toivakka, Martti
    Abo Akad Univ, Ctr Funct Mat, Lab Paper Coating & Converting, SF-20500 Turku, Finland..
    Continuous Processing of Nanocellulose and Polylactic Acid into Multilayer Barrier Coatings2019Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 12, s. 11920-11927Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent years have seen an increased interest toward utilizing biobased and biodegradable materials for barrier packaging applications. Most of the abovementioned materials usually have certain shortcomings that discourage their adoption as a preferred material of choice. Nanocellulose falls into such a category. It has excellent barrier against grease, mineral oils, and oxygen but poor tolerance against water vapor, which makes it unsuitable to be used at high humidity. In addition, nanocellulose suspensions' high viscosity and yield stress already at low solid content and poor adhesion to substrates create additional challenges for high-speed processing. Polylactic acid (PLA) is another potential candidate that has reasonably high tolerance against water vapor but rather a poor barrier against oxygen. The current work explores the possibility of combining both these materials into thin multilayer coatings onto a paperboard. A custom-built slot-die was used to coat either microfibrillated cellulose or cellulose nanocrystals onto a pigment-coated baseboard in a continuous process. These were subsequently coated with PLA using a pilot-scale extrusion coater. Low-density polyethylene was used as for reference extrusion coating. Cationic starch precoating and corona treatment improved the adhesion at nanocellulose/baseboard and nanocellulose/PLA interfaces, respectively. The water vapor transmission rate for nanocellulose + PLA coatings remained lower than that of the control PLA coating, even at a high relative humidity of 90% (38 degrees C). The multilayer coating had 98% lower oxygen transmission rate compared to just the PLA-coated baseboard, and the heptane vapor transmission rate reduced by 99% in comparison to the baseboard. The grease barrier for nanocellulose + PLA coatings increased 5-fold compared to nanocellulose alone and 2-fold compared to PLA alone. This approach of processing nanocellulose and PLA into multiple layers utilizing slot-die and extrusion coating in tandem has the potential to produce a barrier packaging paper that is both 100% biobased and biodegradable.

  • 178.
    Koskela, Salla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wang, Shennan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Xu, Dingfeng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Yang, Xuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Li, Kai
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    McKee, Lauren S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Bulone, Vincent
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Lytic polysaccharide monooxygenase (LPMO) mediated production of ultra-fine cellulose nanofibres from delignified softwood fibres2019Inngår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The production of cellulose nanofibres (CNFs) typically requires harsh chemistry and strong mechanical fibrillation, both of which have negative environmental impacts. A possible solution is offered by lytic polysaccharide monooxygenases (LPMOs), oxidative enzymes that boost cellulose fibrillation. Although the role of LPMOs in oxidative modification of cellulosic substrates is rather well established, their use in the production of cellulose nanomaterials is not fully explored, and the effect of the carbohydrate-binding module (CBM) on nanofibrillation has not yet been reported. Herein, we studied the activity of two LPMOs, one of which was appended to a CBM, on delignified softwood fibres for green and energy-efficient production of CNFs. The CNFs were used to prepare cellulose nanopapers, and the structure and properties of both nanofibres and nanopapers were determined. Both enzymes were able to facilitate nanocellulose fibrillation and increase colloidal stability of the produced CNFs. However, the CBM-lacking LPMO was more efficient in introducing carboxyl groups (0.53 mmol/g) on the cellulose fibre surfaces and releasing CNFs with thinner width (4.3 ± 1.5 nm) from delignified spruce fibres than the modular LPMO (carboxylate content of 0.38 mmol/g and nanofibre width of 6.7± 2.5 nm through LPMO pretreatment followed by mild homogenisation. The prepared nanopapers showed improved mechanical properties (tensile strength of 262 MPa, and modulus of 16.2 GPa) compared to conventional CNFs preparation methods, demonstrating the potential of LPMOs as green alternatives for cellulose nanomaterials preparation.

  • 179.
    Koskela, Salla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Wang, Shennan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Yang, Xuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Li, Kai
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH Royal Inst Technol, Glycosci, Stockholm, Sweden..
    Srivastava, Vaibhav
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    McKee, Lauren S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Bulone, Vincent
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. KTH Royal Inst Technol, Glycosci, Stockholm, Sweden..
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Enzyme-assisted preparation of nanocellulose from wood holocellulose fibers2019Annet (Annet vitenskapelig)
  • 180.
    Kottwitz, Matthew
    et al.
    Univ Illinois, Dept Chem, 1209 W Calif St, Urbana, IL 61801 USA..
    Li, Yuanyuan
    SUNY Stony Brook, Dept Mat Sci & Chem Engn, Stony Brook, NY 11794 USA..
    Palomino, Robert M.
    Brookhaven Natl Lab, Div Chem, Upton, NY 11973 USA..
    Liu, Zongyuan
    Brookhaven Natl Lab, Div Chem, Upton, NY 11973 USA..
    Wang, Guangjin
    Hubei Engn Univ, Coll Chem & Mat Sci, Xiaogan 432000, Peoples R China.;Foshan Univ, Sch Mat Sci & Energy Engn, Foshan 528000, Peoples R China..
    Wu, Qin
    Brookhaven Natl Lab, Ctr Funct Nanomat, Upton, NY 11973 USA..
    Huang, Jiahao
    SUNY Stony Brook, Dept Mat Sci & Chem Engn, Stony Brook, NY 11794 USA..
    Timoshenko, Janis
    SUNY Stony Brook, Dept Mat Sci & Chem Engn, Stony Brook, NY 11794 USA..
    Senanayake, Sanjaya D.
    Brookhaven Natl Lab, Div Chem, Upton, NY 11973 USA..
    Balasubramanian, Mahalingam
    Argonne Natl Lab, Adv Photon Source, Lemont, IL 60439 USA..
    Lu, Deyu
    Brookhaven Natl Lab, Ctr Funct Nanomat, Upton, NY 11973 USA..
    Nuzzo, Ralph G.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. Univ Illinois, Dept Chem, 1209 W Calif St, Urbana, IL 61801 USA..
    Frenkel, Anatoly I.
    SUNY Stony Brook, Dept Mat Sci & Chem Engn, Stony Brook, NY 11794 USA.;Brookhaven Natl Lab, Div Chem, Upton, NY 11973 USA..
    Local Structure and Electronic State of Atomically Dispersed Pt Supported on Nanosized CeO22019Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 9, nr 9, s. 8738-8748Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Single atom catalysts (SACs) have shown high activity and selectivity in a growing number of chemical reactions. Many efforts aimed at unveiling the structure-property relationships underpinning these activities and developing synthesis methods for obtaining SACs with the desired structures are hindered by the paucity of experimental methods capable of probing the attributes of local structure, electronic properties, and interaction with support-features that comprise key descriptors of their activity. In this work, we describe a combination of experimental and theoretical approaches that include photon and electron spectroscopy, scattering, and imaging methods, linked by density functional theory calculations, for providing detailed and comprehensive information on the atomic structure and electronic properties of SACs. This characterization toolbox is demonstrated here using a model single atom Pt/CeO2 catalyst prepared via a sol-gel-based synthesis method. Isolated Pt atoms together with extra oxygen atoms passivate the (100) surface of nanosized ceria. A detailed picture of the local structure of Pt nearest environment emerges from this work involving the bonding of isolated Pt2+ ions at the hollow sites of perturbed (100) surface planes of the CeO2 support, as well as a substantial (and heretofore unrecognized) strain within the CeO2 lattice in the immediate vicinity of the Pt centers. The detailed information on structural attributes provided by our approach is the key for understanding and improving the properties of SACs.

  • 181.
    Kozhevnikov, Evgeny
    et al.
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Qiao, Shupei
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Han, Fengtong
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Yan, Wei
    Harbin Med Univ, Dept Cardiol, Affiliated Hosp 1, Harbin, Heilongjiang, Peoples R China..
    Zhao, Yufang
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Hou, Xiaolu
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Acharya, Alaka
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Shen, Yijun
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Tian, Hui
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Zhang, Haijiao
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    Chen, Xiongbiao
    Univ Saskatchewan, Dept Mech Engn, Saskatoon, SK, Canada..
    Zheng, Yuanchuan
    Harbin Inst Technol, Sch Chem & Chem Engn, Harbin, Heilongjiang, Peoples R China..
    Yan, Hongji
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Guo, Mian
    Harbin Med Univ, Affiliated Hosp 2, Dept Neurosurg, Harbin, Heilongjiang, Peoples R China..
    Tian, Weiming
    Harbin Inst Technol, Sch Life Sci & Technol, Harbin, Heilongjiang, Peoples R China..
    A dual-transduction-integrated biosensing system to examine the 3D cell-culture for bone regeneration2019Inngår i: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 141, artikkel-id UNSP 111481Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three-dimensional (3D) cell cultures developed with living cells and scaffolds have demonstrated outstanding potential for tissue engineering and regenerative medicine applications. However, no suitable tools are available to monitor dynamically variable cell behavior in such a complex microenvironment. In particular, simultaneously assessing cell behavior, cell secretion, and the general state of a 3D culture system is of a really challenging task. This paper presents our development of a dual-transduction-integrated biosensing system that assesses electrical impedance in conjunction with imaging techniques to simultaneously investigate the 3D cell-culture for bone regeneration. First, we created models to mimic the dynamic deposition of the extracellular matrix (ECM) in 3D culture, which underwent osteogenesis by incorporating different amounts of bone-ECM components (collagen, hydroxyapatite [HAp], and hyaluronic acid [HA]) into alginate-based hydrogels. The formed models were investigated by means of electrical impedance spectroscopy (EIS), with the results showing that the impedances increased linearly with collagen and hyaluronan, but changed in a more complex manner with HAp. Thereafter, we created two models that consisted of primary osteoblast cells (OBs), which expressed the enhanced green fluorescent protein (EGFP), and 4T1 cells, which secreted the EGFP-HA, in the alginate hydrogel. We found the capacitance (associated with impedance and measured by EIS) increased with the increases in initial embedded OBs, and also confirmed the cell proliferation over 3 days with the EGFP signal as monitored by the fluorescent imaging component in our system. Interestingly, the change in capacitance is found to be associated with OB migration following stimulation. Also, we show higher capacitance in 4T1 cells that secret HA when compared to control 4T1 cells after a 3-day culture. Taken together, we demonstrate that our biosensing system is able to investigate the dynamic process of 3D culture in a non-invasive and real-time manner.

  • 182.
    Kozhuharov, Svilen
    et al.
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Radiom, Milad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Maroni, Plinio
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Borkovec, Michal
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Persistence Length of Poly(vinyl amine): Quantitative Image Analysis versus Single Molecule Force Response2018Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, nr 10, s. 3632-3639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Single molecules of poly(vinyl amine) are analyzed in the adsorbed state by atomic force microscopy (AFM) in two different ways. First, high-resolution images of individual adsorbed polymers were recorded in monovalent electrolyte solutions. The backbone of the imaged polymers was digitized, and the directional correlation function and internal mean-square end-to-end distance were evaluated. These quantities were analyzed with the wormlike chain (WLC) model, and the persistence length was extracted. Second, individual polymer chains were picked up from the surface, and their force extension behavior was recorded in the same electrolyte solutions. These force profiles were also interpreted in terms of the WLC model, whereby the elastic contribution was also considered. Both techniques yield the persistence length of the polymer. From imaging one obtains a persistence length of about 1.6 nm, while the force experiments yield a value around 0.51 nm. We suspect that the force experiments reflect the intrinsic part of the persistence length, while the imaging experiments yield the persistence length including the electrostatic

  • 183.
    Kravchenko, Oleksandr
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Timmer, Brian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Biedermann, Maurice
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Inge, Ken
    Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden..
    Ramström, Olof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Univ Massachusetts, Dept Chem, Lowell, MA USA..
    Stable CAAC-based complexes in dynamic olefin metathesis2018Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Artikkel i tidsskrift (Annet vitenskapelig)
  • 184. Kumagai, Y.
    et al.
    Barreiro Fidalgo, Alexandre
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Jonsson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Impact of Stoichiometry on the Mechanism and Kinetics of Oxidative Dissolution of UO 2 Induced by H 2 O 2 and γ-Irradiation2019Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, nr 15, s. 9919-9925Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radiation-induced oxidative dissolution of uranium dioxide (UO 2 ) is one of the most important chemical processes of U driven by redox reactions. We have examined the effect of UO 2 stoichiometry on the oxidative dissolution of UO 2 in aqueous sodium bicarbonate solution induced by hydrogen peroxide (H 2 O 2 ) and γ-ray irradiation. By comparing the reaction kinetics of H 2 O 2 between stoichiometric UO 2.0 and hyper-stoichiometric UO 2.3 , we observed a significant difference in reaction speed and U dissolution kinetics. The stoichiometric UO 2.0 reacted with H 2 O 2 much faster than the hyper-stoichiometric UO 2.3 . The U dissolution from UO 2.0 was initially much lower than that from UO 2.3 but gradually increased as the oxidation by H 2 O 2 proceeded. Increase in the initial H 2 O 2 concentration caused decrease in the U dissolution yield with respect to the H 2 O 2 consumption both for UO 2.0 and UO 2.3 . This decrease in the U dissolution yield is attributed to the catalytic decomposition of H 2 O 2 on the surface of UO 2 . The γ-ray irradiation induced the U dissolution that is analogous to the kinetics by the exposure to a low concentration (2 × 10 -4 mol dm -3 ) of H 2 O 2 . The exposure to higher H 2 O 2 concentrations caused lower U dissolution and resulted in deviation from the U dissolution behavior by γ-ray irradiation.

  • 185.
    Kärkäs, Markus D.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Electrochemical strategies for C-H functionalization and C-N bond formation2018Inngår i: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 47, nr 15, s. 5786-5865Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Conventional methods for carrying out carbon-hydrogen functionalization and carbon-nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon-carbon and carbon-heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon-hydrogen functionalization and carbon-nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.

  • 186.
    Kärkäs, Markus D.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Svante Arrhenius väg 16C, SE-106 91 Stockholm, Sweden.
    Lignin Hydrogenolysis: Improving Lignin Disassembly through Formaldehyde Stabilization2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 10, s. 2111-2115Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Lignocellulosic biomass is available in large quantities and constitutes an attractive feedstock for the sustainable production of bulk and fine chemicals. Although methods have been established for the conversion of its cellulosic fractions, valorization of lignin has proven to be challenging. The difficulty in disassembling lignin originates from its heterogeneous structure and its propensity to undergo skeletal rearrangements and condensation reactions during biorefinery fractionation or biomass pretreatment processes. A strategy for hindering the generation of these resistive interunit linkages during biomass pretreatment has now been devised using formaldehyde as a stabilizing agent. The developed method when combined with Ru/C‐catalyzed hydrogenolysis allows for efficient disassembly of all three biomass fractions: (cellulose, hemicellulose, and lignin) and suggests that lignin upgrading can be integrated into prevailing biorefinery schemes.

  • 187.
    Kärkäs, Markus D.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Svante Arrhenius väg 16C, SE-106 91 Stockholm, Sweden.
    Photochemical Generation of Nitrogen-Centered Amidyl, Hydrazonyl, and Imidyl Radicals: Methodology Developments and Catalytic Applications2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, s. 4999-5022Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    During the past decade, visible light photocatalysis has become a powerful synthetic platform for promoting challenging bond constructions under mild reaction conditions. These photocatalytic systems rely on harnessing visible light energy for synthetic purposes through the generation of reactive but controllable free radical species. Recent progress in the area of visible light photocatalysis has established it as an enabling catalytic strategy for the mild and selective generation of nitrogen-centered radicals. The application of visible light for photocatalytic activation of amides, hydrazones, and imides represents a valuable approach for facilitating the formation of nitrogen-centered radicals. Within the span of only a couple of years, significant progress has been made for expediting the generation of amidyl, hydrazonyl, and imidyl radicals from a variety of precursors. This Perspective highlights the recent advances in visible light-mediated generation of these radicals. A particular emphasis is placed on the unique ability of visible light photocatalysis in accessing elusive reaction manifolds for the construction of diversely functionalized nitrogen-containing motifs and as a platform for nontraditional bond disconnections in contemporary synthetic chemistry.

  • 188.
    Kärkäs, Markus D.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
    Bosque, Irene
    Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
    Magallanes, Gabriel
    Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
    Rigoulet, Mathilde
    Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
    Stephenson, Corey R. J.
    Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
    Redox Catalysis Facilitates Lignin Depolymerization2017Inngår i: Synform, nr 11, s. A189-A192Artikkel, forskningsoversikt (Annet vitenskapelig)
    Abstract [en]

    The laboratory of Professor Corey Stephenson at the University of Michigan (Ann Arbor, USA) has had an interest in lignin depolymerization since 2014. According to Corey Stephenson there were two main reasons that initially attracted their attention towards lignin. On the one hand, there is its abundance and unique aromatic backbone, which makes it an exceptional renewable source for small aromatic chemicals. On the other hand there are only few examples of selective methodologies found in the literature regarding its depolymerization, a majority of them employing harsh conditions due to its recalcitrant nature. He added: “Since the major interest of my laboratory focuses on harnessing the energy of visible light, we saw the opportunity of using photoredox catalysis to selectively cleave the ß-O–4 bonds present in the lignin backbone, a methodology that proved to be exceptionally robust for lignin model systems.

    However, a prior oxidation step was required to achieve this fragmentation, which prompted us to search for alternative oxidation methodologies.” Such a method is presented in the present ACS Central Science publication.”

  • 189.
    Kärkäs, Markus D.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
    Bosque, Irene
    Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
    Matsuura, Bryan S.
    Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
    Stephenson, Corey R. J.
    Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
    Photocatalytic Oxidation of Lignin Model Systems by Merging Visible-Light Photoredox and Palladium Catalysis2016Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 18, nr 19, s. 5166-5169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignin valorization has long been recognized as a sustainable solution for the renewable production of aromatic compounds. Two-step oxidation/reduction strategies, whereby the first oxidation step is required to “activate” lignin systems for controlled fragmentation reactions, have recently emerged as viable routes toward this goal. Herein we describe a catalytic protocol for oxidation of lignin model systems by combining photoredox and Pd catalysis. The developed dual catalytic protocol allowed the efficient oxidation of lignin model substrates at room temperature to afford the oxidized products in good to excellent yields.

  • 190.
    Kärkäs, Markus D.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Li, Ying-Ying
    Huazhong Univ Sci & Technol, Sch Chem & Chem Engn, Key Lab Mat Chem Energy Convers & Storage, Hubei Key Lab Mat Chem & Serv Failure,Minist Educ, Wuhan 430074, Hubei, Peoples R China..
    Siegbahn, Per E. M.
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Liao, Rong-Zhen
    Huazhong Univ Sci & Technol, Sch Chem & Chem Engn, Key Lab Mat Chem Energy Convers & Storage, Hubei Key Lab Mat Chem & Serv Failure,Minist Educ, Wuhan 430074, Hubei, Peoples R China..
    Åkermark, Björn
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Metal-Ligand Cooperation in Single-Site Ruthenium Water Oxidation Catalysts: A Combined Experimental and Quantum Chemical Approach2018Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, nr 17, s. 10881-10895Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Catalysts for oxidation of water to molecular oxygen are essential in solar-driven water splitting. In order to develop more efficient catalysts for this oxidatively demanding reaction, it is vital to have mechanistic insight in order to understand how the catalysts operate. Herein, we report the mechanistic details associated with the two Ru catalysts 1 and 2. Insight into the mechanistic landscape of water oxidation catalyzed by the two single-site Ru catalysts was revealed by the use of a combination of experimental techniques and quantum chemical calculations. On the basis of the obtained results, detailed mechanisms for oxidation of water by complexes 1 and 2 are proposed. Although the two complexes are structurally related, two deviating mechanistic scenarios are proposed with metal-ligand cooperation being an important feature in both processes. The proposed mechanistic platforms provide insight for the activation of water or related small molecules through nontraditional and previously unexplored routes.

  • 191.
    Kärkäs, Markus D.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109, United States.
    Porco, John A. Jr
    Department of Chemistry, Center for Molecular Discovery (BU-CMD), Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
    Stephenson, Corey R. J.
    Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
    Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis2016Inngår i: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 116, nr 17, s. 9683-9747Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The use of photochemical transformations is a powerful strategy that allows for the formation of a high degree of molecular complexity from relatively simple building blocks in a single step. A central feature of all light-promoted transformations is the involvement of electronically excited states, generated upon absorption of photons. This produces transient reactive intermediates and significantly alters the reactivity of a chemical compound. The input of energy provided by light thus offers a means to produce strained and unique target compounds that cannot be assembled using thermal protocols. This review aims at highlighting photochemical transformations as a tool for rapidly accessing structurally and stereochemically diverse scaffolds. Synthetic designs based on photochemical transformations have the potential to afford complex polycyclic carbon skeletons with impressive efficiency, which are of high value in total synthesis.

  • 192.
    Leandri, V.
    et al.
    Uppsala Univ, Dept Chem, Angstrom Lab, S-75120 Uppsala, Sweden..
    Yang, W.
    Uppsala Univ, Dept Chem, Angstrom Lab, S-75120 Uppsala, Sweden.;Imperial Coll London, Dept Chem, London SW7 2AZ, England..
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Boschloo, G.
    Uppsala Univ, Dept Chem, Angstrom Lab, S-75120 Uppsala, Sweden..
    Ott, S.
    Uppsala Univ, Dept Chem, Angstrom Lab, S-75120 Uppsala, Sweden..
    Rapid Microwave-Assisted Self-Assembly of a Carboxylic-Acid-Terminated Dye on a TiO2 Photoanode2018Inngår i: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 1, nr 1, s. 202-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Self-assembly of carboxylic-acid-functionalized dyes on mesoporous, anatase TiO2 is at the heart of dye-sensitized solar cells (DSSCs). However, the process often requires 6-20 h of electrode immersion at room temperature in the dye-bath solutions. Here, we introduce a new, rapid microwave-assisted sensitization technique (MINAS), which significantly accelerates the sensitization process and yields high-quality, self-assembled films of an organic dye within 5 min. Targeted experiments show that the effects of the microwave radiation cannot be explained purely on the basis of the thermal component. The interaction of the microwave radiation with the conductive fluorine-doped tin oxide (FTO) electrical contact is a key aspect to consider and a unique feature of MWAS that is the likely cause for producing rapid self-assembly of the dye on the surface.

  • 193.
    Leandri, Valentina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Daniel, Quentin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Kloo, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Electronic and Structural Effects of Inner Sphere Coordination of Chloride to a Homoleptic Copper(II) Diimine Complex2018Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, nr 8, s. 4556-4562Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reaction of CuCl2 with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of [Cu(dmp)(2)](Cl)(2) but instead to [Cu(dmp)(2)Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu-(dmp)(2)Cl]PF6 exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E-1/2 = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)(2)](+), as one may expect. Instead, [Cu(dmp)(2)](+) is isolated as a product when the reduction of [Cu(dmp)(2)Cl]PF6 is performed with L-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)(2)](2+) complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of [Cu(dmp)(2)](ClO4)(2) crystals in acetonitrile results in a 5-coordinated complex, [Cu(dmp)(2)(CH3CN)](ClO4)(2), in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)(2)(CH3CN)](2+) is identical to the one of [Cu(dmp)(2)](+), if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.

  • 194.
    Leandri, Valentina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Jonsson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis2019Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, nr 11, s. 6667-6674Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we have assessed coumarin as a quantitative probe for hydroxyl radical formation in heterogeneous photocatalysis. Upon reaction with the hydroxyl radical, coumarin produces several hydroxylated products, of which one, 7-OH-coumarin, is strongly fluorescent. The fluorescence emission is strongly affected by inner filtering due to the presence of coumarin. Therefore, we performed a series of calibration experiments to correct for the coumarin concentration. From the calibration experiments, we could verify that the inner-filtering effect can be attributed to the competing absorption of the fluorescence excitation light between coumarin and 7-OH-coumarin. Through judicious calibration for the inner-filtering effects, the corrected results for the photocatalytic system show that the rate of hydroxyl scavenging is constant with time for initial coumarin concentrations of ≥50 μM under the conditions of our experiments. The rate increases linearly with coumarin concentration, as expected from the Langmuir–Hinshelwood model. Within the coumarin concentration range used here, the photocatalyst surface does not become saturated. Given the fact that the highest coumarin concentration used (1 mM) in this work is quite close to the solubility limit, we conclude that coumarin cannot be used to assess the full photocatalytic capacity of the system, i.e., surface saturation is never reached. The rate of hydroxyl radical scavenging will, to a large extent, depend on the affinity to the surface, and it is therefore not advisable to use coumarin as a probe for photocatalytic efficiency when comparing different photocatalysts.

  • 195.
    Leandri, Valentina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Jonsson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Reply to "Comment on 'Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis'"2019Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, nr 33, s. 20685-20686Artikkel i tidsskrift (Annet vitenskapelig)
  • 196.
    Leandri, Valentina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Liu, Peng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Sadollahkhani, Azar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Safdari, Majid
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Kloo, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Excited-State Dynamics of [Ru(bpy)(3)](2+) Thin Films on Sensitized TiO2 and ZrO22019Inngår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 20, nr 4, s. 618-626Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The excited state dynamics of Tris(2,2 '-bipyridine)ruthenium(II) hexafluorophosphate, [Ru(bpy)(3)(PF6)(2)], was investigated on the surface of bare and sensitized TiO2 and ZrO2 films. The organic dyes LEG4 and MKA253 were selected as sensitizers. A Stern-Volmer plot of LEG4-sensitized TiO2 substrates with a spin-coated [Ru(bpy)(3)(PF6)(2)] layer on top shows considerable quenching of the emission of the latter. Interestingly, time-resolved emission spectroscopy reveals the presence of a fast-decay time component (25 +/- 5 ns), which is absent when the anatase TiO2 semiconductor is replaced by ZrO2. It should be specified that the positive redox potential of the ruthenium complex prevents electron transfer from the [Ru(bpy)(3)(PF6)(2)] ground state into the oxidized sensitizer. Therefore, we speculate that the fast-decay time component observed stems from excited-state electron transfer from [Ru(bpy)(3)(PF6)(2)] to the oxidized sensitizer. Solid-state dye sensitized solar cells (ssDSSCs) employing MKA253 and LEG4 dyes, with [Ru(bpy)(3)(PF6)(2)] as a hole-transporting material (HTM), exhibit 1.2 % and 1.1 % power conversion efficiency, respectively. This result illustrates the possibility of the hypothesized excited-state electron transfer.

  • 197.
    Leandri, Valentina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Pizzichetti, Angela Raffaella Pia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Xu, Bo
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Franchi, Daniele
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Zhang, Wei
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Benesperi, Iacopo
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Freitag, Marina
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. DUT, DUT KTH Joint Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Exploring the Optical and Electrochemical Properties of Homoleptic versus Heteroleptic Diimine Copper(I) Complexes2019Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, nr 18, s. 12167-12177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to ligand scrambling, the synthesis and investigation of the properties of heteroleptic Cu(I) complexes can be a challenging task. In this work, we have studied the optical and electrochemical properties of a series of homoleptic complexes, such as [Cu(dbda)(2)](+), [Cu(dmp)(2)](+), [Cu(Br-dmp)(2)](+), [Cu(bcp)(2)](+), [Cu(dsbtmp)(2)](+), [Cu(biq)(2)](+), and [Cu(dap)(2)](+) in solution, and those of their heteroleptics [Cu(dbda)(dmp)](+), [Cu(dbda)(Br-dmp)](+), [Cu(dbda)(bcp)](+), [Cu(dbda)(dsbtmp))(+), [Cu(dbda)(biq)](+), [Cu(dbda)(dap)](+) adsorbed on the surface of anatase TiO2 (dbda = 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid; dmp = 2,9-dimethyl-1,10-phenanthroline; Br-dmp = 5-bromo 2,9-dimethyl-1,10-phenanthroline; bcp = bathocuproine or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; dsbtmp = 2,9-di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline; biq = 2,2'-biquinoline; dap = 2,9-dianisyl-1,10-phenanthroline). We show that the maximum absorption wavelengths of the heteroleptic complexes on TiO2 can be reasonably predicted from those of the homoleptic complexes in solution through a simple linear relation, whereas the prediction of their redox properties is less trivial. In the latter case, two different linear patterns emerge: one including the ligands bcp, biq, and dap and another one including the ligands dmp, Br-dmp, and dsbtmp. We offer an interpretation of the data based on the chemical structure of the ligands. On one hand, ligands bcp, biq, and dap possess a more extended pi-conjugated system, which gives a more prominent contribution to the overall redox properties of the ligand dbda. On the other hand, the ligands dmp, Br-dmp, and dsbtmp are all phenanthroline-based containing alkyl substituents and contribute less than dbda to the overall redox properties.

  • 198.
    Lebedova, Jana
    et al.
    Karolinska Inst, Inst Environm Med, Nobels Vag 13, S-17177 Stockholm, Sweden.;Masaryk Univ, RECETOX, Kamenice 753-5,Pavilon A29, CZ-62500 Brno, Czech Republic..
    Hedberg, Yolanda
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Karlsson, Hanna L.
    Karolinska Inst, Inst Environm Med, Nobels Vag 13, S-17177 Stockholm, Sweden..
    Size-dependent genotoxicity of silver, gold and platinum nanoparticles studied using the mini-gel comet assay and micronucleus scoring with flow cytometry2018Inngår i: Mutagenesis, ISSN 0267-8357, E-ISSN 1464-3804, Vol. 33, nr 1, s. 77-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metallic nanoparticles (NPs) are promising nanomaterials used in different technological solutions as well as in consumer products. Silver (Ag), gold (Au) and platinum (Pt) represent three metallic NPs with current or suggested use in different applications. Pt is also used as vehicle exhaust catalyst leading to a possible exposure via inhalation. Despite their use, there is limited data on their genotoxic potential and possible size-dependent effects, particularly for Pt NPs. The aim of this study was to explore size-dependent genotoxicity of these NPs (5 and 50 nm) following exposure of human bronchial epithelial cells. We characterised the NPs and assessed the viability (Alamar blue assay), formation of DNA strand breaks (mini-gel comet assay) and induction of micronucleus (MN) analysed using flow cytometry (in vitro microflow kit). The results confirmed the primary size (5 and 50 nm) but showed agglomeration of all NPs in the serum free medium used. Slight reduced cell viability (tested up to 50 mu g/ml) was observed following exposure to the Ag NPs of both particle sizes as well as to the smallest (5 nm) Au NPs. Similarly, at non-cytotoxic concentrations, both 5 and 50 nm-sized Ag NPs, as well as 5 nm-sized Au NPs, increased DNA strand breaks whereas for Pt NPs only the 50 nm size caused a slight increase in DNA damage. No clear induction of MN was observed in any of the doses tested (up to 20 mu g/ml). Taken together, by using the comet assay our study shows DNA strand breaks induced by Ag NPs, without any obvious differences in size, whereas effects from Au and Pt NPs were size-dependent in the sense that the 5 nm-sized Au NPs and 50 nm-sized Pt NPs particles were active. No clear induction of MN was observed for the NPs.

  • 199. Lee, H.
    et al.
    Wu, X.
    Yang, X.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Ligand-Controlled Electrodeposition of Highly Intrinsically Active and Optically Transparent NiFeOxHy Film as a Water Oxidation Electrocatalyst2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 23, s. 4690-4694Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly intrinsically active and optically transparent NiFeOxHy water oxidation catalyst was prepared by electrodeposition of [Ni(C12-tpen)](ClO4)2 complex (Ni−C12). This NiFeOxHy film has a current density of 10 mA cm−2 with an overpotential (η) of only 298 mV at nanomolar concentration and the current density of 10 mA cm−2 remains constant over 22 h in 1 m KOH. The extremely high turnover frequency of 0.51 s−1 was obtained with η of 300 mV. More importantly, such outstanding activity and transparency (optical loss <0.5 %) of the NiFeOxHy film are attributed to a ligand effect of the dodecyl substituent in Ni−C12, which enables its future application in solar water splitting.

  • 200.
    Lee, Husileng
    et al.
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wu, Xiujuan
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Ye, Qilun
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wu, Xingqiang
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wang, Xiaoxiao
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Zhao, Yimeng
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Hierarchical CoS2/Ni3S2/CoNiOx nanorods with favorable stability at 1 A cm(-2) for electrocatalytic water oxidation2019Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, nr 11, s. 1564-1567Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, we have reported an easily synthesized CoS2/Ni3S2/CoNiOx water oxidation catalyst with excellent catalytic activity and superior durability. The as-prepared catalyst required overpotential (eta) as low as 256 mV to exhibit a current density of 10 mA cm(-2) in 1.0 M KOH. Remarkably, it sustained a current density of 1 A cm(-2) for one week in 30% KOH solution with only 25 mV increment of eta. Thus, it is a hopeful candidate as a highly-effective water oxidation electrode in practical applications.

1234567 151 - 200 of 454
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