Change search
Refine search result
123456 151 - 200 of 288
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 151.
    Lu, Huiran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Leijonmarck, Simon
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry. Swerea KIMAB AB.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Cornell, Ann M.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Flexible Paper Electrodes for Li-Ion Batteries Using Low Amount of TEMPO-Oxidized Cellulose Nanofibrils as Binder2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 28, p. 18097-18106Article in journal (Refereed)
    Abstract [en]

    Flexible Li-ion batteries attract increasing interest for applications in bendable and wearable electronic devices. TEMPO-oxidized cellulose nanofibrils (TOCNF), a renewable material, is a promising candidate as binder for flexible Li-ion batteries with good mechanical properties. Paper batteries can be produced using a water-based paper making process, avoiding the use of toxic solvents. In this work, finely dispersed TOCNF was used and showed good binding properties at concentrations as low as 4 wt %. The TOCNF was characterized using atomic force microscopy and found to be well dispersed with fibrils of average widths of about 2.7 nm and lengths of approximately 0.1-1 mu m. Traces of moisture, trapped in the hygroscopic cellulose, is a concern when the material is used in Li-ion batteries. The low amount of binder reduces possible moisture and also increases the capacity of the electrodes, based on total weight. Effects of moisture on electrochemical battery performance were studied on electrodes dried at 110 degrees C in a vacuum for varying periods. It was found that increased drying time slightly increased the specific capacities of the LiFePO4 electrodes, whereas the capacities of the graphite electrodes decreased. The Coulombic efficiencies of the electrodes were not much affected by the varying drying times. Drying the electrodes for 1 h was enough to achieve good electrochemical performance. Addition of vinylene carbonate to the electrolyte had a positive effect on cycling for both graphite and LiFePO4. A failure mechanism observed at high TOCNF concentrations is the formation of compact films in the electrodes.

  • 152.
    Lu, Huiran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Hagberg, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Li4Ti5O12 flexible, lightweight electrodes based on cellulose nanofibrils as binder and carbon fibers as current collectors for Li-ion batteries2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 39, p. 140-150Article in journal (Refereed)
    Abstract [en]

    TEMPO oxidized cellulose nanofibrils (TOCNF) were used as binder material to prepare bendable Li4Ti5O12 (LTO) electrodes. Carbon fiber (CF) layers were integrated as current collectors to enhance the mechanical properties and to increase the specific energy of the electrodes. These electrodes combined with CF current collectors (LTO/CF) show good electrochemical properties and are flexible, sustainable, mechanical and chemical stable, lightweight and produced by a water-based easy filtration process. An increase of the active material weight (LTO) from around 19% to 71% of the electrode and current collector combined weight is demonstrated with CF compared with a copper current collector. Additionally, preparation of the current collector material is non-expensive, quick and easy compared to that of carbon nanotube or graphene. To test the flexible battery application, 4000 times repeated bending was carried out on both the LTO electrodes and the LTO/CF electrodes. This had no significant effect on the morphology, mechanical and electrochemical properties of neither the LTO nor the LTO/CF electrodes. Addition of the CF layer improves the mechanical properties and specific capacity of the LTO-electrode. A thicker LTO electrode with only 2 wt% TOCNF is demonstrated which is promising for thicker electrodes with high energy density. A full cell was assembled with the LTO/CF as negative electrode and LiFePO4 (LFP)/CF as positive, which exhibited a stable cycling performance and good energy density.

  • 153. Lu, Zhansheng
    et al.
    Yang, Zongxian
    Hermansson, Kersti
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Castleton, Christopher W. M.
    Several different charge transfer and Ce3+ localization scenarios for Rh-CeO2(111)2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 7, p. 2333-2345Article in journal (Refereed)
    Abstract [en]

    We present DFT+U based electronic structure calculations in a p(3 x 3) slab supercell, for low coverages of atomically dispersed Rh interacting with the CeO2(111) surface, comparing Rh as an adatom, and as a dopant substituted into the surface layer. We find that, energetically, a Rh atom approaching a ceria(111) surface with both sparse O and Ce vacancies present strongly prefers to heal the Ce vacancies, but next it prefers to adsorb on a stoichiometric region rather than healing an O vacancy. In the adatom system, Rh is oxidized by electron transfer to a 4f orbital on one Ce ion in the surface layer, which is then nominally converted from Ce4+ -> Ce3+ (i.e. Rh adatoms are single donors). We show that there are a number of different local minima, with Ce3+ localization at 1st, 2nd or 3rd nearest neighbour Ce sites. The second neighbour is the most stable, but all are close in energy. In the Rh-doped system (Rh replaces Ce), Rh is oxidized by charge transfer to neighbouring O atoms, and Rh doping leads to deep acceptor and donor states. Rh is not stable in the O sublattice. Moreover, based on vacancy formation energies, we find that oxygen vacancy formation is strongly enhanced in the vicinity of Rh dopants, but slightly suppressed in the vicinity of Rh adatoms.

  • 154.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Materials characterization of thin film electrodes for PEFC - Survey of methods and an example2004In: Journal of New Materials for Electrochemical Systems, ISSN 1480-2422, Vol. 7, no 1, p. 21-28Article in journal (Refereed)
    Abstract [en]

    Thorough materials characterization is an essential tool for obtaining a deeper understanding of the electrochemical processes taking place in thin film electrodes of polymer fuel cells. This paper gives a survey of different methods for characterizing materials properties that are relevant to the electrochemical performance of such electrodes (i.e. loading, thickness, electrical conductivity, porosity, pore size distribution and pore morphology). The use of these materials characterization methods is exemplified, among other things it is shown that the ionomer (Nafion(R)) in a thin-film electrode made by the spraying method is homogeneously distributed in pores smaller than 40 nm. Furthermore, the ionomer penetrates and/or encapsulates the primary carbon particles of 30 nm. The results are discussed in relation to different MEA fabrication methods.

  • 155.
    Luo, T.
    et al.
    Aix Marseille Univ, Fac St Jerome, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France..
    Mangelinck, D.
    Aix Marseille Univ, Fac St Jerome, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France..
    Descoins, M.
    Aix Marseille Univ, Fac St Jerome, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France..
    Bertoglio, M.
    Aix Marseille Univ, Fac St Jerome, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France..
    Mouaici, N.
    Ecole Natl Mines & Met ENSMM Annaba, Ex CEFOS Chaiba BP 233 RP Annaba,W129, Sidi Amar, Algeria..
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT).
    Girardeaux, C.
    Aix Marseille Univ, Fac St Jerome, CNRS, IM2NP, Case 142, F-13397 Marseille 20, France..
    Combined effect of Pt and Walloying elements on Ni-silicide formation2018In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 123, no 12, article id 125301Article in journal (Refereed)
    Abstract [en]

    A combinatorial study of the combined effect of Pt and W on Ni silicide formation is performed. Ni(Pt, W) films with thickness and composition gradients were prepared by a co-deposition composition spread technique using sputtering deposition from Pt, W, and Ni targets. The deposited Ni(Pt, W) films were characterized by X-ray diffraction, X-ray reflectivity, Rutherford backscattering, and atom probe tomography. The maximum content of alloying elements is close to 27 at. %. Simulations of the thickness and composition were carried out and compared with experimental results. In situ X-ray diffraction and atom probe tomography were used to study the phase formation. Both additive alloying elements (Pt + W) slow down the Ni consumption and the effect of W is more pronounced than the one of Pt. Regarding the effect of alloying elements on Ni silicides formation, three regions could be distinguished in the Ni(Pt, W)/Si wafer. For the region close to the Ni target, the low contents of alloying elements (Pt + W) have little impact on the phase sequence (delta-Ni2Si is the first silicide and NiSi forms when Ni is entirely consumed) but the kinetics of silicide formation slows down. The region close to the Pt target has high contents of (Pt + W) and is rich in Pt and a simultaneous phase formation of delta-Ni(2)Sii and NiSi is observed. For the high (PtthornW) contents and W-rich region, NiSi forms unexpectedly before delta-Ni2Si and the subsequent growth of delta-Ni2Si is accompanied by the NiSi consumption. When Ni is entirely consumed, NiSi regrows at the expense of delta-Ni2Si.

  • 156.
    Lyne, Bruce
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Commercially available nanomaterials for inclusion in forest products2011In: TAPPI Int. Conf. Nanotechnology Renew. Mater., 2011, p. 944-956Conference paper (Refereed)
  • 157.
    Ma, Ying
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Ceria-based Nanostructured Materials for Low-Temperature Solid Oxide Fuel Cells2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    As one of the most efficient and environmentally benign energy conversion devices, solid oxide fuel cells (SOFC) have attracted much attention in recent years. Conventional SOFC with yttria-stabilized zirconia as electrolyte require high operation temperature (800-1000 °C), which causes significant problems like material degradation, as well as other technological complications and economic barrier for wider applications. Therefore, there is a broad interest in reducing the operation temperature of SOFCs. One of the most promising ways to develop low-temperature SOFCs (LTSOFC) is to explore effective materials for each component with improved properties. So in this thesis, we are aiming to design and fabricate ceria-based nanocomposite materials for electrolyte and electrodes of LTSOFC by a novel nanocomposite approach.

    In the first part of the thesis, novel core-shell doped ceria/Na2CO3 nanocomposite was fabricated and investigated as electrolytes materials of LTSOFC. Two types of doped ceria were selected as the main phase for nanocomposite: samarium doped ceria (SDC) and calcium doped ceria (CDC). The core-shell SDC/Na2CO3 nanocomposite particles are smaller than 100 nm with amorphous Na2CO3 shell of 4~6 nm in thickness. The ionic conductivity of nanocomposite electrolytes were investigated by EIS and four-probe d.c. method, which demonstrated much enhanced ionic conductivities compared to the single phase oxides. The thermal stability of such nanocomposite has also been investigated based on XRD, BET, SEM and TGA characterization after annealing samples at various temperatures. Such nanocomposite was applied in LTSOFCs with an excellent power density of 0.8 Wcm-2 at 550 °C. The high performances together with notable thermal stability prove the doped ceria/Na2CO3 nanocomposite as a potential electrolyte material for long-term LTSOFCs.

    In the second part of the thesis, a novel template-, surfactant-free chemical synthetic route has been successfully developed for the controlled synthesis of hierarchically structured CeO2 with nanowires and mesoporous microspheres morphologies. The new synthetic route was designed by utilizing the chelate formation between cerium ion and various carboxylates forms of citric acid. Then, hierarchically structured cerium oxide with morphologies of nanowires and mesoporous microspheres can be obtained by thermal decomposition of the two kinds of precursors. Moreover, by doping with desired elements, SDC nanowires and SDC-CuO mesoporous microspheres were prepared and used for electrolyte and anode materials, respectively, based on their unique properties depending on their morphologies. When SDC nanowires/Na2CO3 composite were applied as electrolyte for single SOFC, and it exhibited maximum power density of 522 mWcm-2 at 600 °C, which is much better than the state-of-the-art SOFCs using doped ceria as electrolytes. Besides, the mesoporous CuO-SDC composite anode was synthesized by our microwave-assisted method, which shows good phase homogeneity of both SDC and CuO. When it was applied for fuel cells, the cell had better performance than conventional CuO-SDC anode prepared by solid state method.

    The whole work of this thesis aims to provide a new methodology for the entire SOFC community. It is notable that our work has attracted considerable attention after publication of several attached papers. The results in this thesis may benefit the development of LTSOFC and expand the related research to a new horizon.

  • 158. Malti, Abdellah
    et al.
    Edberg, Jesper
    Granberg, Hjalmar
    Khan, Zia Ullah
    Andreasen, Jens W.
    Liu, Xianjie
    Zhao, Dan
    Zhang, Hao
    Yao, Yulong
    Brill, Joseph W.
    Engquist, Isak
    Fahlman, Mats
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Crispin, Xavier
    Berggren, Magnus
    An Organic Mixed Ion-Electron Conductor for Power Electronics2016In: Advanced Science, ISSN 2198-3844, Vol. 3, no 2, article id UNSP 1500305Article in journal (Refereed)
    Abstract [en]

    A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting nanopaper are exploited in devices which exhibit record values for the charge storage capacitance (1F) in supercapacitors and transconductance (1S) in electrochemical transistors.

  • 159. Martinez-Sanz, Marta
    et al.
    Olsson, Richard T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lopez-Rubio, Amparo
    Lagaron, Jose M.
    Development of electrospun EVOH fibres reinforced with bacterial cellulose nanowhiskers. Part I: Characterization and method optimization2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18, no 2, p. 335-347Article in journal (Refereed)
    Abstract [en]

    In the present study, hybrid electrospun EVOH fibres reinforced with bacterial cellulose nanowhiskers (BCNW) were developed and characterized. The nanowhiskers, obtained by sulphuric acid digestion of native bacterial cellulose mats generated by Gluconacetobacter xylinum, were morphologically characterized by SEM and optical microscopy with polarized light and revealed a highly crystalline structure of nanofibrils aggregates. XRD analyses suggested a crystalline structure corresponding to the cellulose I allomorph. It was also confirmed by means of FT-IR spectroscopy that amorphous regions were preferentially digested by the acid treatment, whereas TGA analyses showed a decrease in the thermal stability of the nanowhiskers most likely due to incorporation of sulphate groups and the inherent acidity remaining in the filler even after extensive washing cycles. A method was developed for improving the incorporation of BCNW within the EVOH electrospun fibres, consisting on the addition of the BCNW in the form of a centrifuged precipitate, versus the most conventionally employed freeze-dried nanowhiskers. DSC analyses showed a significant increase in the glass transition temperature of the composites during the second heating run, which may be related to the acidic character of the nanofiller. Finally, sonication was seen to enhance interfacial interaction but to reduce the incorporation of the filler in the matrix in the case of the centrifuged material.

  • 160.
    Matsushita, Taishi
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Däcker, C. -Å
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Thermophysical properties of mould flux from Swedish steel companies2008In: Proc. ICS 2008: The 4th Int. Congress Sci. Technol. Steelmaking, 2008, p. 718-721Conference paper (Refereed)
  • 161.
    Mazinanian, Neda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Metal Release and Corrosion of Stainless Steel in Simulated Food Contact2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Knowledge on metal release behaviour of stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessments. Recently, a new European test guideline (the CoE protocol) has been implemented to ensure safety of metals and alloys in food contact, such as stainless steels. This guideline suggests 5 gL-1 citric acid (pH 2.4) as a food simulant for acidic foods of pH ≤ 4.5. So far, limited assessments exist that investigate the correlation between the bioaccessibility, material characteristics, corrosion behaviour and surface chemistry of stainless steel for food application tests using citric acid. Therefore, this doctoral thesis comprises an in–depth interdisciplinary and multi–analytical research effort to fill this knowledge gap.

    This work includes thorough investigations of a range of stainless steel grades in simulated food contact as a function of different important parameters such as grades, surface finish, temperature, pH, solution composition, metal complexation and buffering capacity, concentration of the complex forming agents, loading, and repeated usage. This is accomplished by kinetic studies of metal release, electrochemical, and surface analytical investigations. Another focus of this thesis is to assess the dominating metal release process in citric acid or chloride containing solutions of varying pH.

    This study suggests protonation (at acidic pH) and surface complexation (at weakly acidic and neutral pH) as the predominant metal release mechanisms for stainless steel in citric acid solutions. Solution complexation may also play a role by hindering metal precipitation at weakly acidic and neutral pH, and metal release from surface defects / inclusions may initially be important for non-passivated surfaces.

  • 162.
    Mazinanian, Neda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Karolinska Institutet, Sweden.
    Metal Release Mechanisms for Passive Stainless Steel in Citric Acid at Weakly Acidic pH2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 10, p. C686-C693Article in journal (Refereed)
    Abstract [en]

    Metal release investigations from stainless steel into citric acid (CA) solutions at near-neutral pH are relevant for food applications, cleaning, and passivation. This study investigated metal release from abraded stainless steel grade AISI 304 into 5 g/L CA at pH 3.1, 4.8, and 6.4 at 40°C, as compared to a control solution (10 mM KNO3). Polyacrylic acid (PAA) was used as a model solution with and without separation from the stainless steel surface by a membrane. No significant difference was found for the released amounts of Fe and Mn between CA, PAA, and KNO3 solutions at pH 3.1, suggesting other mechanisms than complexation. At pH 4.8 and 6.4, a significantly higher release was found for CA and PAA solutions compared with KNO3 solution, but not for PAA solution when PAA molecules could not reach the stainless steel surface due to membrane separation, implying a dominant complexation-induced metal release mechanism that requires adsorption and/or close vicinity of the complexing agent to the surface. Cr was enriched in the surface oxide (surface passivation) in complexing solutions and the release of Cr was most dependent on complexation by CA at pH 4.8 and 6.4.

  • 163.
    Mazinanian, Neda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nickel release and surface characteristics of fine powders of nickel metal and nickel oxide in media of relevance for inhalation and dermal contact2013In: Regulatory toxicology and pharmacology, ISSN 0273-2300, E-ISSN 1096-0295, Vol. 65, no 1, p. 135-146Article in journal (Refereed)
    Abstract [en]

    Differences in surface oxide characteristics and extent of nickel release have been investigated in two thoroughly characterized micron-sized (mainly <4 mu m) nickel metal powders and a nickel oxide bulk powder when immersed in two different synthetic fluids, artificial sweat (ASW-pH 6.5) and artificial lysosomal fluid (ALF-pH 4.5) for time periods up to 24 h. The investigation shows significantly more nickel released from the nickel metal powders (<88%) compared to the NiO powder (<0.1%), attributed to differences in surface properties. Significantly more nickel was released from the nickel metal powder with a thin surface oxide predominantly composed of non-stoichiometric nickel oxide (probably Ni2O3), compared to the release from the nickel metal powder with a thicker surface oxide predominantly composed of NiO and to a lesser extent Ni2O3 (88% and 25% release after 24 h in ALF, respectively). Significantly lower amounts of nickel were released from the nickel metal powders in ASW (2.2% and <1%, respectively). The importance of particle and surface characteristics for any reliable risk assessment is discussed, and generated data compared with literature findings on bioaccessibility (released fraction) of nickel from powders of nickel metal and nickel oxide, and massive forms of nickel metal and nickel-containing alloys.

  • 164.
    Mazinanian, Neda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Herting, Gunilla
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Metal release and corrosion resistance of different stainless steel grades in simulated food contact2016In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 72, no 6, p. 775-790Article in journal (Refereed)
    Abstract [en]

    A new technical guideline has been implemented by the Council of Europe (CoE) to ensure the stability and safety of food contact articles of metals and alloys, using 5 g/L citric acid (pH 2.4) and artificial tap water DIN 10531 (pH 7.5) as food simulants. The objectives of this study were: (i) to quantify the extent of metal release from austenitic (grades AISI 201, 204, 304, and 316L), ferritic (grades AISI 430 and EN 1.4003), and lean duplex stainless steel (grade EN 1.4162) in citric acid (5 g/L, pH 2.4) and in artificial tap water (pH 7.5); (ii) to compare the release of metals to the surface oxide composition, the open circuit potential-time dependence, and the corrosion resistance; and (iii) to elucidate the combined effect of high chloride concentrations (0.5 M NaCl) and citric acid at pH 2.2 and 5.5 on the extent of metal release from AISI 304 with and without prior surface passivation by citric acid. Exposures of all stainless steel grades in citric acid and artificial tap water up to 10 d (at 70°C/40°C) resulted in lower metal release levels than the specific release limits stipulated within the CoE protocol. For all grades, metals were released at levels close to the detection limits when exposed to artificial tap water, and higher release levels were observed when exposed to citric acid. Increased surface passivation, which resulted in reduced metal release rates with time, took place in citric acid for all grades and test conditions (e.g., repeated exposure at 100°C). There was no active corrosion in citric acid at pH 2.4. Fe (in citric acid) and Mn (in all solutions, but mostly tap water) were preferentially released, as compared to their bulk alloy content, from all stainless steel grades. Ni was released to the lowest extent. 0.5 M NaCl induced a very low (close to detection limits) metal release from grade AISI 304 at pH 5.5. When combined with citric acid (5 g/L) and at lower pH (2.2), 0.5 M NaCl induced slightly higher metal release compared to citric acid (pH 2.4) alone for coupons that were not pre-passivated. Pre-passivation in 5 g/L citric acid (pH 2.4) at 70°C for 2 h largely reduced this solution dependence. Pre-passivation resulted in an up to 27-fold reduced extent of metal release in solutions containing citric acid and/or NaCl at pH 2.2 to 5.5, and resulted in improved reproducibility among replicate samples.

  • 165.
    Mazinanian, Neda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Influence of Citric Acid on the Metal Release of Stainless Steels2015In: Corrosion Science and Technology, ISSN 1598-6462, Vol. 14, no 4, p. 166-171Article in journal (Refereed)
    Abstract [en]

    Knowledge of how metal releases from the stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessment. A new European standard test protocol for testing metal release in food contact materials made from metals and alloys has recently been published by the Council of Europe. The major difference from earlier test protocols is the use of citric acid as the worst-case food simulant. The objectives of this study were to assess the effect of citric acid at acidic, neutral, and alkaline solution pH on the extent of metal release for stainless steel grades AISI 304 and 316, commonly used as food contact materials. Both grades released lower amounts of metals than the specific release limits when they were tested according to test guidelines. The released amounts of metals were assessed by means of graphite furnace atomic absorption spectroscopy, and changes in the outermost surface composition were determined using X-ray photoelectron spectroscopy. The results demonstrate that both the pH and the complexation capacity of the solutions affected the extent of metal release from stainless steel and are discussed from a mechanistic perspective. The outermost surface oxide was significantly enriched in chromium upon exposure to citric acid, indicating rapid passivation by the acid. This study elucidates the effect of several possible mechanisms, including complex ion- and ligand-induced metal release, that govern the process of metal release from stainless steel under passive conditions in solutions that contain citric acid.

  • 166.
    Midander, Klara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Bioaccessibility of nano- and micron-sized metallic particles in simulated lung systems2008Conference paper (Refereed)
    Abstract [en]

    Ambient airborne particles of varying size and composition, originating from anthropogenic and natural sources are today a recognized health risk in the society. The rapid development of engineered nanomaterials, including particles, is believed to become an issue of large concern. At present, few efforts have been made to investigate potential adverse health effects of nano- and micron sized metallic particles. Reliable data on surface properties and reactivity of metallic particles and its correlation to toxicity is scarce. Bioaccessibility data, in terms of metal release, is believed to reflect the toxic effects of metallic particles. The metal release process is influenced by particle size, i.e. surface area, shape and material type, e.g. passive/non-passive, pure/alloy/oxide as well as the exposure environment, e.g. within the lung. The assessment of potentially adverse health effects due to particles requires the correlation between toxic effects, bioaccessibility properties and surface characteristics. Within this context, the material aspects of metal release from Cu-particles were studied in-vitro by exposure in different synthetic biological media that simulate, to some extent, a realistic inhalation scenario. Particle toxicity in terms of DNA damage and cytotoxic effects was studied in collaboration with human toxicologists at Karolinska Institutet, and aerosol scientists at Stockholm University, using epithelial human lung cells.

  • 167.
    Mikhaylova, Maria
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Kim, Do-Kyung
    KTH, Superseded Departments, Materials Science and Engineering.
    Berry, CC
    Zagorodni, Andrei
    KTH, Superseded Departments, Materials Science and Engineering.
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Curtis, ASG
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    BSA immobilization on amine-functionalized superparamagnetic iron oxide nanoparticles2004In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 16, no 12, p. 2344-2354Article in journal (Refereed)
    Abstract [en]

    Immobilization of bovine serum albumin (BSA) on surface-modified superparamagnetic iron oxide nanoparticles (SPION) has been performed by two different double-step immobilization approaches. The first approach consists of preparation of SPION by controlled chemical coprecipitation in the presence of BSA solution, whereas the second approach includes preliminary surface modification of SPION with an amine group using a coupling agent of 3-aminepropyltrimethoxysilane (APTMS). Both procedures are followed by 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide hydrochloride (EDC) activation with sequential immobilization of the layer of BSA. Additionally, an attempt to modify the surface of SPION with amine and carboxylic groups is undertaken by using L-aspartic acid (LAA). TEM shows that the particle size varies in the range 10-15 nm and does not change significantly after the coating process. The presence of BSA and amine groups on the surface of SPION is confirmed by FT-IR. Magnetic properties are investigated by VSM and results indicate that the superparamagnetic properties are retained for BSA-coated SPION while reducing the value of saturation magnetization (M-s). The binding capacity is estimated from thermo-gravimetric and chemical analyse;. APTMS-coated SPION show higher BSA binding capacity compared to that of coprecipitated SPION in the presence of BSA. In vitro tests have been performed after the functionalization of SPION with LAA and BSA. Human dermal fibroblasts are incubated with the surface-modified SPION for 6 and 24 h to observe cell behavior, morphology, cytoskeletal organization, and interactions between cell and SPION. BSA-coated SPION incubated with cells demonstrated a cell response similar to that of control cells, with no adverse cell damage and no endocytosis, whereas LAA-coated SPION show partial endocytosis without cytoskeletal disorganization.

  • 168. Mille, C.
    et al.
    Tyrode, Eric C.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Corkery, Robert W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630).
    3-D chiral photonic crystals replicated from butterfly wing scales2011In: Materials Research Society Symposium Proceedings: Volume 1389, 2011, p. 7-12Conference paper (Refereed)
    Abstract [en]

    Three dimensional silica photonic crystals with the gyroid minimal surface structure have been synthesized using the butterfly Callophrys rubi as a template. The replicas are synthesized with a high degree of fidelity, which is confirmed by the spectral and morphological characterization. Further, the material is shown to be optically active.

  • 169. Mishra, G.
    et al.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sharma, A.
    Multifunctional Mesoporous Carbon Capsules and their Robust Coatings for Encapsulation of Actives: Antimicrobial and Anti-bioadhesion Functions2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 23, p. 19371-19379Article, review/survey (Refereed)
    Abstract [en]

    We present the synthesis and applications of multifunctional hollow porous carbon spheres with well-ordered pore architecture and ability to encapsulate functional nanoparticles. In the present work, the applications of hollow mesoporous carbon capsules (HMCCs) are illustrated in two different contexts. In the first approach, the hollow capsule core is used to encapsulate silver nanoparticles to impart antimicrobial characteristics. It is shown that silver-loaded HMCCs (concentration ?100 μg/mL) inhibit the growth and multiplication of bacterial colonies of Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) up to 96% and 83%, respectively. In the second part, the fabrication of hierarchical micro- and nanostructured superhydrophobic coatings of HMCCs (without encapsulation with silver nanoparticles) is evaluated for anti-bioadhesion properties. Studies of protein adsorption and microorganism and platelet adhesion have shown a significant reduction (up to 100%) for the HMCC-based superhydrophobic surfaces compared with the control surfaces. Therefore, this unique architecture of HMCCs and their coatings with the ability to encapsulate functional materials make them a promising candidate for a variety of applications.

  • 170. Mishra, Y. K.
    et al.
    Natarajan Arul, Murugan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Kotakoski, J.
    Adam, J.
    Progress in electronics and photonics with nanomaterials2017In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 146, p. 304-307Article in journal (Refereed)
    Abstract [en]

    Nanomaterials have been at the center of attraction for almost five decades as their contributions to different disciplines such as electronics, photonics and medicine are enormous. Various kinds of nanomaterials have been developed and are currently utilized in innumerable applications. Nevertheless, their simple realization and easy and efficient upscaling are topics under intense investigation. Innovative strategies have been adopted for nanomaterial synthesis and their usability. Here, we provide a brief overview on nanomaterials ranging from basic understanding of their structure-property relationship to advanced applications. This editorial covers various aspects about nanomaterials, which will be useful/attractive for beginners in the field of nanotechnology as well as for experts and for industrialists looking forward to exploit them for real world applications.

  • 171.
    Mittal, Nitesh
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Biotechnology (BIO), Protein Technology. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Jansson, Ronnie
    KTH, School of Biotechnology (BIO), Protein Technology.
    Widhe, Mona
    KTH, School of Biotechnology (BIO), Protein Technology.
    Benselfelt, Tobias
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Innventia AB, Sweden.
    Håkansson, Karl M. O.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Biotechnology (BIO), Protein Technology. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Hedhammar, My
    KTH, School of Biotechnology (BIO), Protein Technology.
    Söderberg, Daniel
    KTH, School of Biotechnology (BIO), Protein Technology. KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ultrastrong and Bioactive Nanostructured Bio-Based Composites2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 5, p. 5148-5159Article in journal (Refereed)
    Abstract [en]

    Nature’s design of functional materials relies on smart combinations of simple components to achieve desired properties. Silk and cellulose are two clever examples from nature–spider silk being tough due to high extensibility, whereas cellulose possesses unparalleled strength and stiffness among natural materials. Unfortunately, silk proteins cannot be obtained in large quantities from spiders, and recombinant production processes are so far rather expensive. We have therefore combined small amounts of functionalized recombinant spider silk proteins with the most abundant structural component on Earth (cellulose nanofibrils (CNFs)) to fabricate isotropic as well as anisotropic hierarchical structures. Our approach for the fabrication of bio-based anisotropic fibers results in previously unreached but highly desirable mechanical performance with a stiffness of ∼55 GPa, strength at break of ∼1015 MPa, and toughness of ∼55 MJ m–3. We also show that addition of small amounts of silk fusion proteins to CNF results in materials with advanced biofunctionalities, which cannot be anticipated for the wood-based CNF alone. These findings suggest that bio-based materials provide abundant opportunities to design composites with high strength and functionalities and bring down our dependence on fossil-based resources.

  • 172. Molochnikov, L S
    et al.
    Kovalyova, E G
    Grigor'ev, I A
    Zagorodni, Andrei A.
    KTH, Superseded Departments, Materials Science and Engineering.
    Direct measurement of H+ activity inside cross-linked functional polymers using nitroxide spin probes2004In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 4, p. 1302-1313Article in journal (Refereed)
    Abstract [en]

    The lack of a direct method for measuring activity inside ion-exchamye resins was the main obstacle for strict thermodynamic investigations of such objects during the past decades. This paper proposes a method for the activity determination. The method is based on exploring the ESR response of stable nitroxide radicals introduced as probes into the resin phase. This method allows for the measurement of the hydrogen ion activity inside cross-linked polyelectrolytes. In addition to the method verification, the paper reports its application to the determination of ionization constants of functional groups and to the investigation of the hydrolysis and sorption of copper on different types of sorbents (weak cation and anion-exchange resins, functionalized and nonfunctionalized polymeric films). The applicability of known thermodynamic approaches developed for the investigation of micelles and biomembranes with nitroxide radicals is discussed. The paper also includes a critical analysis of the potentiometric method conventionally used for the investigation of ion-exchange equilibria.

  • 173.
    Mongkhontreerat, Surinthra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Öberg, Kim
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Erixon, Lina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Löwenhielm, Peter
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    UV initiated thiol-ene chemistry: a facile and modular synthetic methodology for the construction of functional 3D networks with tunable properties2013In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 1, no 44, p. 13732-13737Article in journal (Refereed)
    Abstract [en]

    A facile methodology for the fabrication of functional crosslinked three dimensional (3D) networks has herein been explored via the benign and UV initiated thiol-ene coupling (TEC) chemistry. The careful selection of monomers or polymers and their feed ratio resulted in straightforward design of organic, inorganic and hydrogel networks with readily available alkenes or thiol functional groups. All crosslinked networks were fabricated within 1 second of UV exposure at wavelengths of 320-390 nm and generally exhibited excellent gel fractions around 90%. By introducing off-stoichiometric thiol and ene (OSTE) monomer feed ratios the window of mechanical properties could be manipulated. For the organic triazine system, the Young's modulus was altered from 780 MPa at an equimolar monomer ratio to soft 106 kPa for 2.5 equiv. with excess of thiol compared to enes. Postfunctionalizations with hydrophilic polyethylene glycols or acrylic acid and hydrophobic heneicosa-fluorododecyl acrylate were explored for the manipulation of functional networks. In this case, the rigid networks with excess of thiols were used as model substrates of which the initial contact angle (CA) of 60 degrees was decreased to 43 degrees by the introduction of acrylic acid and increased to 140 degrees by successful attachment of fluorinated molecules. Finally, amalgamating micropatterning strategy with simple postfunctionalizations of hydrophobic groups resulted in superhydrophobic rigid surfaces with a CA of 173 degrees.

  • 174. Moriana, Rosana
    et al.
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ribes-Greus, Amparo
    Improved thermo-mechanical properties by the addition of natural fibres in starch-based sustainable biocomposites2011In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 42, no 1, p. 30-40Article in journal (Refereed)
    Abstract [en]

    Sustainable biocomposites based on thermoplastic starch copolymers (Mater-Bi KE03B1) and biofibres (cotton, hemp and kenaf) were prepared and characterised in terms of their thermo-mechanical and morphological properties. Biocomposites exhibit improved thermal stability and mechanical properties in comparison with the Mater-Bi KE. Biofibres act as suitable thermal stabilizers for the Mater-Bi KE, by increasing the maximum decomposition temperature and the Ea associated to the thermal decomposition process. Biofibre addition into the Mater-Bi KE results in higher storage modulus and in a reduction of the free-volume-parameter associated to the Mater-Bi KE glass transition. The influence of different biofibres on the thermo-mechanical properties of the biocomposites has been discussed. Hemp and kenaf enhance the thermal stability and reduce the free volume-parameter of Mater-Bi KE more significantly than cotton fibres, although the latter exhibits the highest mechanical performance. These differences may be explained by the improved interaction of lignocellulosic fibres with the Mater-Bi KE, due to the presence of hemicellulose and lignin in their formulation.

  • 175. Muhmood, L.
    et al.
    Viswanathan, N. N.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    A new approach for the diffusion coefficient evaluation of sulfur in CaO-SiO2-Al2O3 slag2011In: 6th International Conference on Diffusion in Solids and Liquids, DSL-2010, 2011, p. 626-634Conference paper (Refereed)
    Abstract [en]

    The Diffusion coefficient of sulfur in a ternary slag with composition of 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 was measured at 1723 K by chemical diffusion from the variation of concentration of sulfur in silver metal. A MATLAB program was developed to find the concentration variation of sulfur in silver metal using various critical parameters like the diffusion coefficient of sulfur in slag available in literature, sulfur partition ratio, sulfide capacity of the slag and the its density. The P S2 and PO2 pressures were calculated from the Gibbs energy of the equilibrium reaction between CaO in the slag and solid CaS and confirming the same by using ThermoCalc. The density of the slag at 1723 K was obtained from earlier experiments. Initially the order of magnitude for the diffusion coefficient was taken from the works of Saito and Kawai but later was modified so that the concentration changes of Sulfur obtained from the program agreed with the experimental results. The diffusion coefficient of sulfur in 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 slag at 1723 K was estimated as 4.14×10-6 cm2/sec.

  • 176. Naderi, Ali
    et al.
    Lindstrom, Tom
    Weise, Christoph F.
    Flodberg, Goren
    Sundstrom, Jonas
    Junel, Kristina
    Erlandsson, Johan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Runebjork, AnneMarie
    Phosphorylated nanofibrillated cellulose: production and properties2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 1, p. 20-29Article in journal (Refereed)
    Abstract [en]

    Phosphate functionalized nanofibrillated cellulose (NFC) was produced through an industrially attractive process, by reacting wood pulp with a phosphate containing salt, followed by mechanical delamination through microfluidization. The degrees of delamination of the phosphorylated NFCs (judged by among others AFM-imaging, rheological studies and tensile strength measurements on NFC films) were found to improve with increasing functionalization of the pulp and number of microfluidization-passes. The NFC systems were found to display similar characteristics as other well-known NFC systems. Interestingly, however, the sufficiently delaminated phosphorylated NFCs exhibited significantly lower oxygen permeability values (at RH 50%) than the published values of several well-known highly delaminated NFC systems. The potential application of the phosphorylated NFC in packaging applications can hence be envisaged.

  • 177.
    Neranon, Kitjanit
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stimuli-Responsive, Multivalent Glycodendrimer/Metalloglycodendrimer Assemblies for Targeted DeliveryManuscript (preprint) (Other academic)
  • 178.
    Nordenström, Malin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Riazanova, Anastasia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Järn, Mikael
    RISE Res Inst Sweden, Div Biosci & Mat, SE-11428 Stockholm, Sweden..
    Paulraj, Thomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Turner, Charlotta
    Lund Univ, Dept Chem, SE-22100 Lund, Sweden..
    Ström, Valter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Olsson, Richard
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Svagan, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Superamphiphobic coatings based on liquid-core microcapsules with engineered capsule walls and functionality2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 3647Article in journal (Refereed)
    Abstract [en]

    Microcapsules with specific functional properties, related to the capsule wall and core, are highly desired in a number of applications. In this study, hybrid cellulose microcapsules (1.2 +/- 0.4 mu m in diameter) were prepared by nanoengineering the outer walls of precursor capsules. Depending on the preparation route, capsules with different surface roughness (raspberry or broccoli-like), and thereby different wetting properties, could be obtained. The tunable surface roughness was achieved as a result of the chemical and structural properties of the outer wall of a precursor capsule, which combined with a new processing route allowed in-situ formation of silica nanoparticles (30-40 nm or 70 nm in diameter). By coating glass slides with "broccoli-like" microcapsules (30-40 nm silica nanoparticles), static contact angles above 150 degrees and roll-off angles below 6 degrees were obtained for both water and low surface-tension oil (hexadecane), rendering the substrate superamphiphobic. As a comparison, coatings from raspberry-like capsules were only strongly oleophobic and hydrophobic. The liquid-core of the capsules opens great opportunities to incorporate different functionalities and here hydrophobic superparamagnetic nanoparticles (SPIONs) were encapsulated. As a result, magnetic broccoli-like microcapsules formed an excellent superamphiphobic coating-layer on a curved geometry by simply applying an external magnetic field.

  • 179.
    Norlin, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Fabrication of Porous Nb2O5 by Plasma Electrolysis Anodization and Electrochemical Characterization of the Oxide2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 7, p. B225-B230Article in journal (Refereed)
    Abstract [en]

    Porous Nb2O5 electrodes were fabricated by applying anodic pulses of 700 V and 10 ms duration to pure Nb in phosphate bufferedsaline solution (PBS), aiming at biomaterial applications. The porosity of the oxide could be controlled by the number of pulses. X-ray photoelectron spectroscopy analysis confirmed the oxide to be Nb2O5. The electrochemical behavior and interfacial propertiesof the porous Nb2O5 were characterized in PBS by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EIS measurements indicate that the oxide film has a two-layer structure with a compact inner layer and a porousouter layer, and the pores were sealed by precipitates during long-time aging in PBS. The two-layer structure of the oxide film wasobserved by examination of the cross section using scanning electron microscopy in backscatter mode. The CV measurementsreveal that the oxide exhibits an electrochemical “rectifying” property. It is stable over a wide potential range but shows hydrogenuptake upon cathodic polarization below −1 V vs Ag/AgCl.

  • 180.
    Noroozi, Mohammad
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Abedin, Ahmad
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Moeen, Mahdi
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Radamson, Henry H.
    CVD growth of GeSnSiC alloys using disilane, digermane, tin tetrachloride and methylsilane2014In: ECS Transactions, 2014, Vol. 64, no 6, p. 703-710Conference paper (Refereed)
    Abstract [en]

    In this study, Ge1-x-y-zSnxSiyCz layers (0.01≤x≤ 0.06, 0≤y≤0.02 and 0≤z≤0.01) have been successfully grown at 280-330 °C on Ge and Si by using RPCVD technique. It was demonstrated that the quality of epitaxial layers is dependent on the growth parameters, layer thickness and the quality of Ge virtual layer. It was found that a proper strain balance in the matrix during the epitaxy where the Si is adjusted carefully with the Sn flux improves the incorporation of Sn in Ge matrix. A similar improvement of Sn incorporation has been observed for phosphorous, boron and carbon doping in GeSn layers as well. This is explained by the compensation of the compressive strain caused by Snand the tensile strain induced by Si to obtain the minimum energy in Ge matrix. This behavior was not observed for relaxed GeSn layers and Sn incorporation could be controlled only by the growth parameters. The thermal stability of GeSn is an important integration issue for device fabrication. The thermal stability of P- and B-doped GeSn layers was studied by rapid thermal annealing (RTA) in range of 400-600 °C and compared with intrinsic layers. The GeSn layers were stable up to 550 °C while the B-doped layers showed strain relaxation readily at 500 °C. The epitaxial quality of epi-layers was evaluated in terms of oxygen and water vapor contamination. The level of oxygen during epitaxy was as low as 10 ppb and the contamination amount was found as low as 1017 cm-3.

  • 181.
    Nowak, Andrzej
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Hagberg, Johan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Leijonmarck, Simon
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Schweinebarth, Hannah
    Baker, Darren
    Uhlin, Anders
    Tomani, Per
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Lignin-based carbon fibers for renewable and multifunctional lithium-ion battery electrodes2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 2, p. 81-90Article in journal (Refereed)
    Abstract [en]

    Lignin-based carbon fibers (LCFs) from the renewable resource softwood kraft lignin were synthesized via oxidative thermostabilization of pure melt-spun lignin and carbonization at different temperatures from 1000 degrees C to 1700 degrees C. The resulting LCFs were characterized by tensile testing, scanning electron microscopy (SEM), X-ray diffraction (XRD) and confocal Raman spectroscopy. The microstructure is mainly amorphous carbon with some nanocrystalline domains. The strength and stiffness are inversely proportional to the carbonization temperature, while the LCFs carbonized at 1000 degrees C exhibit a strength of 628 MPa and a stiffness of 37 GPa. Furthermore, the application potential of LCFs was evaluated as negative electrodes in a lithium-ion battery (LIB) by electrochemical cycling at different current rates in a half-cell setup. The capacity drops with the carbonization temperature and the LCFs carbonized at 1000 degrees C have a capacity of 335 mAh g(-1). All LCFs showed good cycling stability. Because of the mechanical integrity and conductivity of the LCFs, there is no need to apply current collectors, conductive additives or binders. The advantage is an increased gravimetric energy density compared to graphite, which is the most common negative electrode material. LCFs show a promising multifunctional behavior, including good mechanical integrity, conductivity and an ability to intercalate lithium for LIBs.

  • 182. Ohm, Wiebke
    et al.
    Rothkirch, Andre
    Pandit, Pallavi
    Koerstgens, Volker
    Mueller-Buschbaum, Peter
    Rojas, Ramiro
    Yu, Shun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Brett, Calvin J.
    Soderberg, Daniel L.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Morphological properties of airbrush spray-deposited enzymatic cellulose thin films2018In: JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, ISSN 1945-9645, Vol. 15, no 4, p. 759-769Article in journal (Refereed)
    Abstract [en]

    We investigate the layer formation of enzymatic cellulose by airbrush spray coating on silicon oxide surfaces. The layer structure and morphology of enzymatic cellulose films in the thickness range between 86 nm and 2.1 A mu m is determined as a function of the spray coating procedures. For each spray coating step, layer buildup, surface topography, crystallinity as well as the nanoscale structure are probed with atomic force microscopy and surface-sensitive X-ray scattering methods. Without intermittent drying, the film thickness saturates; with intermittent drying, a linear increase in layer thickness with the number of spray pulses is observed. A closed cellulose layer was always observed. The crystallinity remains unchanged; the nanoscale structures show three distinct sizes. Our results indicate that the smallest building blocks increasingly contribute to the morphology inside the cellulose network for thicker films, showing the importance of tailoring the cellulose nanofibrils. For a layer-by-layer coating, intermittent drying is mandatory.

  • 183.
    Olin, Pontus
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Fundamentals of Wetting and Mechanical Durability of Superhydrophobic Coatings2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In paper I the friction between three different superhydrophobic surfaces and water drops were investigated using high‑speed video. The surfaces were two based on a hydrophobic wax and the third was the leaf of a Lotus (Nelumbo Nucifera). The acceleration of water drops was measured as a function of drop size and surface inclination. For small capillary numbers it was shown that the dissipation was dominated by pinning‑depinning transitions along the trailing contact line. A parameter called the superhydrophobic sliding resistance bsh has been introduced. The motion of drops on superhydrophobic surfaces of a general macroscopic topography can be predicted provided that bsh and the drop size are known. This theory also infers the existence of an equilibrium sliding angle, beq, at which the drop acceleration is zero.

    The effect of line‑shaped defects on the motion of water drops on superhydrophobic surfaces were also investigated using high‑speed video in paper II. It was shown that the motion of the drop in the vicinity of the defect can be approximated by a damped harmonic oscillator. Whether a drop got trapped or not while traversing the defect was determined by the incident speed and the characteristics of the oscillator. In systems with low viscous dissipation it is possible to predict the trapping speed as well as the exit speed using a simple work‑energy consideration.

    The resistance of wax based superhydrophobic coatings subjected to different types of mechanical damage were investigated in paper III. Scratch tests were performed using atomic force microscopy (AFM) and rubbing with an index finger. Coatings were also subjected to compression with a silicone rubber stamp. The effect of impacting water drops was also investigated. A load of 12 nN was enough to remove the coating from the substrate. The coatings remained superhydrophobic at compression pressures up to 59 kPa but the superhydrophobic properties were lost after only one stroke with a finger. The coatings resisted at least 200 000 impacts of falling water drops without losing their superhydrophobic properties.

    In paper IV superhydrophobic coatings were fabricated in a semi‑continuous process, where an alkyl ketene dimer (AKD) was dissolved in supercritical carbon dioxide (scCO2) and sprayed onto the substrate. Several different substrates such as: glass, aluminium, paper, poly (ethylene terephthalate) (PET) and poly (tetrafluoroethylene) (PTFE) were successfully coated. The most efficient spray process, considering surface properties and mass of extracted AKD, was obtained at the lowest temperature investigated, 67 °C, and the highest pressure evaluated in this study, 25 MPa. The influence of the pre‑expansion conditions (p, T) on the surface temperature (at a spray distance of 3 cm) was also shown to be negligible.

  • 184.
    Olin, Pontus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Lindström, Stefan B.
    Solid Mechanics , Department of Management and Engineering, the Institute of Technology, Linköping University.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Trapping of Water Drops by Defects on Superhydrophobic SurfacesManuscript (preprint) (Other academic)
    Abstract [en]

    In this work the effect of line‑shaped defects on the motion of water drops on superhydrophobic surfaces have been investigated using high‑speed video. The defects were introduced on superhydrophobic wax surfaces by a simple scratching method. It is shown that the motion of the drop in the vicinity of the defect can be approximated by a damped harmonic oscillator. Whether a drop gets trapped or not while traversing the defect is determined by the incident speed and the characteristics of the oscillator, more specifically by the damping ratio z and the nondimensional forcing constant â. We also show that it is possible to predict the trapping speed as well as the exit speed using a simple work‑energy consideration in systems with negligible viscous dissipation.

  • 185.
    Olupot, Peter Wilberforce
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Byaruhanga, Joseph K.
    Characterization of feldspar and quartz raw materials in Uganda for manufacture of electrical porcelains2006In: Journal of the Australasian Ceramic Society, ISSN 1018-6689, Vol. 42, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    Electric porcelains are widely used for insulation purposes. The aim of this study is to characterize feldspar and quartz raw materials in Uganda for use in manufacture of electric porcelains. Samples from two deposits of each feldspar and silica are investigated to assess their potential as raw materials in the manufacture of electric porcelains. Raw samples ground to powder form are investigated by means of X-ray diffraction, thermal analysis, and scanning electron microscopy. In addition, the chemical composition, particle size distribution and density of the powders are determined. The study reveals one of the feldspar deposits to consist of purely ordered microcline, while the other has ordered microcline, quartz and albite. The silica deposits are purely of quartz mineral. The materials investigated, are suitable for use in porcelain production.

  • 186.
    Ovaskainen, Louise
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Olin, Pontus
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Tuominen, Mikko
    SP Kemi, Material och Ytor, Drottning Kristinas väg 45, SE-114 86 Stockholm.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wear studies of superhydrophobic coatings of wax sprayed from rapid expansion of supercritical solutions (RESS)Manuscript (preprint) (Other academic)
    Abstract [en]

    The wear resistance of superhydrophobic coatings made by spraying a wax from supercritical carbon dioxide solutions have been evaluated by different methods. Scratch tests were performed by using the tip of the cantilever in an atomic force microscope (AFM) by applying an increasing load force on the tip during the measurement. Compression tests were also performed by applying different loads onto a rubber stamp that was placed on the surfaces. In addition to this, frictional wear was evaluated by moving an index finger over the surface using a device that measured the applied load and frictional forces. The wetting properties of the exposed coatings were subsequently evaluated in terms of advancing and receding water contact angles, the superhydrophobic sliding resistance parameter and the surface roughness (RMS). The morphology of the coatings was studied by scanning electron microscopy and optical profilometry. Scratching, with the AFM, at load forces of 12 nN was enough to fully remove the coating from the underlying silica substrate. Results also show that the surfaces remained superhydrophobic after being exposed to compression loads up to 59 kPa. The frictional wear measurments showed that the superhydrophobic properties were immediately lost after pressing and moving a finger over the coating since the lateral movement destroyed the fine surface structure.  Finally it was found that the surfaces could stand up to 200 000 falling water drops without losing its superhydrophobicity.

  • 187. Pasti, Igor A.
    et al.
    Leetmaa, Mikael
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univiversity, Sweden.
    General principles for designing supported catalysts for hydrogen evolution reaction based on conceptual Kinetic Monte Carlo modeling2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 4, p. 2526-2538Article in journal (Refereed)
    Abstract [en]

    Rational catalyst design presents one of the main paradigms in the contemporary materials science. Although the electronic structure calculations can be used to search for possible candidates, realistic supported catalysts are difficult to address in this way. In this contribution we use conceptual model of the supported hydrogen evolution reaction (HER) catalyst and investigate possible processes using Kinetic Monte Carlo simulations. In specific, we look at the possibility to boost H-2 production by the H spillover to the support and the tailoring of the catalyst deposit. Different scenarios were considered depending on the nature of the HER rate determining step (RDS) on the catalyst surface and the effects of the rates of elementary processes, catalyst dispersion and morphology are analyzed. Metals with low affinity towards hydrogen should be used as catalyst supports, while H spillover can boost H-2 production if Tafel or Heyrovsky reaction is the RDS on the catalyst surface. However, this can be achieved only if the catalyst dispersion is high, while the support has to act as a Hads acceptor and enable fast Hads recombination. General instructions for the choice of the catalystlsupport combination can be used to design new advanced HER catalysts. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  • 188.
    Paulraj, Alagar R.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kiros, Yohannes
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Skårman, B.
    Vidarsson, H.
    Core/shell structure nano-iron/iron carbide electrodes for rechargeable alkaline iron batteries2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 7, p. A1665-A1672Article in journal (Refereed)
    Abstract [en]

    In this work, we have studied a 2% copper substituted core shell type iron/iron carbide as a negative electrode for application in energy storage. The NanoFe-Fe3C-Cu delivered 367 mAh g−1 at ≈80% current efficiency, successfully running for over 300 cycles. The superior electrode kinetics and performance were assessed by rate capability, galvanostatic, potentiodynamic polarization measurements in 6 M KOH electrolyte and at ambient temperature. Ex-situ XRD characterizations and SEM images of both the fresh and used electrode surfaces show that nanoparticles were found to be still intact with negligible particle agglomeration. The electrodes have shown stable performances with low capacity decay, whereas sulfur dissolution from the additive Bi2S3 was found to decrease the charging efficiency with time. This core-shell type structured nano material is, consequently, an auspicious anode candidate in alkaline-metal/air and Ni-Fe battery systems.

  • 189.
    Paulraj, Alagar Raj
    et al.
    KTH Royal Inst Technol, Dept Chem Engn, SE-10044 Stockholm, Sweden..
    Kiros, Yohannes
    KTH Royal Inst Technol, Dept Chem Engn, SE-10044 Stockholm, Sweden..
    Göthelid, Mats
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Johansson, Malin B.
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem, POB 523, SE-75120 Uppsala, Sweden..
    NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media2018In: CATALYSTS, ISSN 2073-4344, Vol. 8, no 8, article id 328Article in journal (Refereed)
    Abstract [en]

    This article reports the two-step synthesis of NiFeOx nanomaterials and their characterization and bifunctional electrocatalytic activity measurements in alkaline electrolyte for metal-air batteries. The samples were mostly in layered double hydroxide at the initial temperature, but upon heat treatment, they were converted to NiFe2O4 phases. The electrochemical behaviour of the different samples was studied by linear sweep voltammetry and cyclic voltammetry on the glassy carbon electrode. The OER catalyst activity was observed for low mass loadings (0.125 mg cm(-2)), whereas high catalyst loading exhibited the best performance on the ORR side. The sample heat-treated at 250 degrees C delivered the highest bi-functional oxygen evolution and reduction reaction activity (OER/ORR) thanks to its thin-holey nanosheet-like structure with higher nickel oxidation state at 250 degrees C. This work further helps to develop low-cost electrocatalyst development for metal-air batteries.

  • 190.
    Petronico, Aaron
    et al.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA..
    Moneypenny, Timothy P., II
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA.;Univ Illinois, Beckman Inst Adv Sci & Technol, Urbana, IL 61801 USA..
    Nicolau, Bruno G.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA..
    Moore, Jeffrey S.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA.;Univ Illinois, Beckman Inst Adv Sci & Technol, Urbana, IL 61801 USA..
    Nuzzo, Ralph G.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Univ Illinois, Dept Chem, Urbana, IL 61801 USA.
    Gewirth, Andrew A.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA..
    Solid-Liquid Lithium Electrolyte Nanocomposites Derived from Porous Molecular Cages2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 24, p. 7504-7509Article in journal (Refereed)
    Abstract [en]

    We demonstrate that solid-liquid nanocomposites derived from porous organic cages are effective lithium ion electrolytes at room temperature. A solid-liquid electrolyte nanocomposite (SLEN) fabricated from a LiTFSI/DME electrolyte system and a porous organic cage exhibits ionic conductivity on the order of 1 x 10(-3) S cm(-1). With an experimentally measured activation barrier of 0.16 eV, this composite is characterized as a superionic conductor. Furthermore, the SLEN displays excellent oxidative stability up to 4.7 V vs Li/Li+. This simple three-component system enables the rational design of electrolytes from tunable discrete molecular architectures.

  • 191.
    Pettersson, Torbjörn
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Pendergraph, Samuel A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Marais, Andrew
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Gustafsson, Emil
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Robust and Tailored Wet Adhesion in Biopolymer Thin Films2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 12, p. 4420-4428Article in journal (Refereed)
    Abstract [en]

    Model layer-by-layer (LbL) assemblies of poly(allylamine hydrochloride) (PAH) and hyaluronic acid (HA) were fabricated in order to study their wet adhesive behavior. The film characteristics were investigated to understand the inherent structures during the assembly process. Subsequently, the adhesion of these systems was evaluated to understand the correlation between the structure of the film and the energy required to separate these LbL assemblies. We describe how the conditions of the LbL fabrication can be utilized to control the adhesion between films. The characteristics of the film formation are examined in the absence and presence of salt during the film formation. The dependence on contact time and LbL film thickness on the critical pull-off force and work of adhesion are discussed. Specifically, by introducing sodium chloride (NaCl) in the assembly process, the pull-off forces can be increased by a factor of 10 and the work of adhesion by 2 orders of magnitude. Adjusting both the contact time and the film thickness enables control of the adhesive properties within these limits. Based on these results, we discuss how the fabrication procedure can create tailored adhesive interfaces with properties surpassing analogous systems found in nature.

  • 192. Piskounova, Sonya
    et al.
    Rojas, Ramiro
    Bergman, Kristoffer
    Hilborn, Jöns
    The Effect of Mixing on the Mechanical Properties of Hyaluronan-Based Injectable Hydrogels2011In: Macromolecular Materials and Engineering, ISSN 1438-7492, Vol. 296, no 10, p. 944-951Article in journal (Refereed)
    Abstract [en]

    A method for determining the correlation between the mixing of two reactive polymers and the structural and mechanical properties of the formed hydrogels is presented. Rheological measurements show that insufficient mixing gives rise to soft and not fully crosslinked hydrogels while excessive mixing beyond gel point results in weaker hydrogels due to potential breakage of their 3D network. Furthermore, the hydrogels swell significantly more in cell culture medium than in phosphate-buffered saline, attributed to interactions with additional molecules such as proteins. Thus, moderate mixing gives rise to the most homogenous and mechanically stable hydrogels and the choice of medium e. g., for release experiments, should be consistent in order to avoid unnecessary variations in the data caused by different swelling profiles.

  • 193. Pu, Tingting
    et al.
    Tan, Wenyi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Nanjing Institute of Technology, Nanjing, China.
    Shi, Huangang
    Na, Yi
    Lu, Jiangang
    Zhu, Bin
    Steam/CO2 electrolysis in symmetric solid oxide electrolysis cell with barium cerate-carbonate composite electrolyte2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 190, p. 193-198Article in journal (Refereed)
    Abstract [en]

    A composite electrolyte, Zr doped BaCe0.8Y0.2O3-delta (BaCe0.8Y0.2O3-delta, BCZY) and binary carbonates [(Li,Na)(2)CO3] (LNCO) was first applied to reduce CO2 accompanied with steam electrolysis in solid oxide electrolysis cell (SOEC) at 600 degrees C, lower than which conventional SOEC composed by YSZ works in (usually above 800 degrees C). Electrolysis performances are improved due to sufficient steam feed at oxygen electrode side (30-110 ml/min). Steam electrolysis provides proton source for the reduction of CO2. Application of composite electrolyte promotes proton transport and directly leads to H-2 even CH4 production. To a certain degree, carbon resistance guarantees the symmetric SOEC operation at a lower bias potential of 0.5 V (vs.00V) applied. A redox-stable and carbon-tolerant LSCM as symmetric electrode with a hybrid-ion-conducting composite electrolyte realizes the fuel synthesis by CO2 reduction in proton-type solid oxide electrolyzer.

  • 194.
    Qin, Haiyan
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Fu, Tao
    Centre for Optical and Electromagnetic Research, Zhejiang University.
    Ning, Zhijun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Controlling Yield and Morphology for GoldNanorods in a Seed-Mediated Synthesis Method forCell Imaging2010In: 2010 OSA-IEEE-COS Advances in Optoelectronics and Micro/Nano-Optics, Institute of Electrical and Electronics Engineers (IEEE), 2010, article id 5713561Conference paper (Refereed)
    Abstract [en]

    Designed experiments are carried out to systematically study the effects of silver ions on morphology and yield of gold nanorods synthesized via a seed-mediated method. Gold nanorods synthesized with different silver ions and CTAB concentrations were characterized by absorption spectroscopy and TEM. The shape and yield of gold nanorods were effectively controlled by adjusting the concentration ratio of CTAB and silver ions for synthesis. Dark field images of a glass slide sample with gold nanorods deposit and a sample with gold nanrods staining cells further confirmed that high quality gold nanorods were obtained.

  • 195.
    Qin, Jian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Environment-Sensitive Multifunctional Drug Delivery Systems2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Drug delivery systems (DDS) with multiple functionalities such as environment-sensitive drug release mechanisms and visualization agents have motivated the biomedical community as well as materials chemists for more than a decade. This dissertation is concerned with the development of nanoparticles for multifunctional DDS  to tackle several crucial challenges in these complex systems, including polymeric nanospheres which respond to temperature change, superparamagnetic iron oxide nanoparticles/polymeric composite for magnetic resonance imaging contrast agents and drug carriers, immunoresponse of nanomaterials and injectable magnetic field sensitive ferrogels.

    The biocompatible and biodegradable polylactide (PLA) was employed as matrix materials for polymeric nanosphere-based DDS. The thermosensitive polymeric nanospheres have been constructed through a “modified double-emulsion method”. The inner shell containing the thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) undergoes a “hydrophilic-to-hydrophobic” phase transition around the human body temperature. The sensitivity of the polymer to the temperature can facilitate drug release at an elevated temperature upon administration. In addition, gold nanoparticles were assembled on the dual-shell structure to form a layer of gold shell. The cell viability was found to be enhanced due to the gold layer. The immunoresponse of the gold nanoparticles has been considered even if no acute cytotoxicity was observed.

    Imaging is another functionality of multifunctional DDS. This work focuses on magnetic resonance imaging (MRI) and involves synthesis and surface modification of superparamagnetic iron oxide nanoparticles (SPIONs) for contrast agents. The SPIONs have been prepared through a high temperature decomposition method. Surface modification was carried out in different ways. Poly(L,L-lactide) (PLLA) was grafted on SPIONs through surface-initiated ring-opening polymerization. The hydrophobic model drug indomethacin was loaded in the PLLA layer of the composite particles. For biomedical applications, it is essential to modify the hydrophobic particles so that they can be dispersed in physiological solutions. A series of protocols including using small charged molecules and amphiphilic polymers has been established. Pluronic F127 (PF127), a triblock copolymer was applied as a phase transfer reagent. Most interestingly, PF127@SPIONs show remarkable efficacy as T2 contrast agents. The PF127@SPIONs have been successfully applied to image the cochlea in a rat model. As another phase transfer reagent, poly(maleic anhydride-alt-octadecene)-graft-PNIPAAm (PMAO-graft-PNIPAAm) was created for surface modification of SPIONs. This new copolymer provides the modified SPIONs with thermosensitivity together with water-dispersibility.

    As another form of DDS, ferrogel made of PF127 copolymer and SPIONs was developed. Gelation process depends on the temperature of the SPIONs/PF127 mixture. This property makes it possible to use the ferrogel as an injectable drug carrier. Unlike other ferrogels based on crosslinked polymeric network, the PF127 ferrogel can entrap and release hydrophobic drugs. Application of an external magnetic field is found to enhance the drug release rate. This property can find application in externally stimulated local drug release applications.

  • 196.
    Qin, Jian
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Nanoparticles for multifunctional drug delivery systems2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Multifunctional drug delivery systems incorporated with stimuli-sensitive drug release, magnetic nanoparticles and magnetic resonance (MR) T2 contrast agents is attracting increasing attention recently. In this thesis, works on polymer nanospheres response to temperature change, superparamagnetic iron oxide nanoparticles (SPION)/polymeric composite materials for MR imaging contrast agents are summarized.

    A “shell-in-shell” polymeric structure has been constructed through a “modified double-emulsion method”. Thermosensitive inner shell is comprised of poly(N-isopropylacrylamide) which undergoes phase transition at body temperature. Such a feature could facilitate drug release at an elevated temperature upon administration. Furthermore, the dual-shell structure is covered by a layer of gold nanoparticles. According to the cytotoxicity tests, the biocompatibility is shown to be enhanced due to the layer of gold.

    SPION have been prepared using a high temperature decomposition method. Particle growth of SPION is monitored by transmission electron microscope and synchrotron X-ray diffraction. Poly(L,L-lactide)@SPION (PLLA@SPION) composite particles have been prepared through surface-initiated ring-opening polymerization which has been developed in our lab. For biomedical applications, it is essential to transfer the particles to physiological solutions from organic solutions. Phase transfer of SPION has been carried out by utilizing small molecules. Stability at the neutral pH is of large concern for such transfer systems. A novel phase transfer agent, Pluronic F127 (PF127), a triblock copolymer has been applied and the stability of the aqueous PF127@oleic acid (OA)@SPION solution has been greatly enhanced over a broad pH range. Most interestingly, PF127@OA@SPION show remarkable efficacy as T2 contrast agents as indicated by relaxometric measurements compared with commercially available products.

  • 197.
    Qin, Jian
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Asempah, Isaac
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Laurent, Sophie
    Department of General Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons-Hainaut.
    Fornara, Andrea
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Muller, Robert N.
    Department of General Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons-Hainaut.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Injectable Superparamagnetic Ferrogels for Controlled Release of Hydrophobic Drugs2009In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 21, no 13, p. 1354-1357Article in journal (Refereed)
    Abstract [en]

    A ferrogel for magnetically controlled release of drugs is prepared by integration of superparamagnetic iron oxide nanoparticles and Pluronic F127 gels. The hydrophobic drug indomethacin is loaded in the ferrogel owing to the oil-in-water micellar structure. The characteristic solgel transition property renders the ferrogel an injectable drug carrier that will be, in principle, free from surgical implant procedure.

  • 198.
    Qin, Jian
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Jo, Yun Suk
    Ihm, Jong Eun
    Kim, Do Kyung
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Thermosensitive nanospheres with a gold layer revealed as low-cytotoxic drug vehicles2005In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 20, p. 9346-9351Article in journal (Refereed)
    Abstract [en]

    In this paper, the positive effect of a gold layer on cell viability is demonstrated by examining the results given by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfop henyl)-2H-tetrazolium (MTS) assay and two-color cell fluorescence viability (TCCV) assay. These cytotoxicity tests were performed with human cervical adenocarcinoma cells (HeLa cell line) and transformed African green monkey kidney fibroblast cells (Cos-7 cell line). To fabricate the nanostructures as drug vehicles, first, poly((L),(L)-lactidec-co-ethylene glycol) (PLLA-PEG) and poly(N-isopropylacrylamide-co-(D),(D)-lactide) (PNIPAAm-PDLA) were synthesized, and then two kinds of thermosensitive nanospheres comprising "shell-in-shell" structures without a gold layer (PLLA-PEG@PNIPAAm-PDLA) and with a gold layer (Au@PLLA-PEG@PNIPAAmPDLA) were constructed by a modified double-emulsion method (MDEM). Both of them displayed a unique thermosensitive character exhibiting the lower critical solubility temperature (LCST) at 36.7 degrees C which was confirmed by LTV-vis spectroscopy and differential scanning calorimetry (DSC). The release profiles of entrapped bovine serum albumin (BSA) were monitored at 22 and 37 degrees C, respectively, to reveal the thermal dependence on the release rate. In cell viability tests, both PLLA-PEG@PNIPAAm-PDLA and Au@PLLAPEGCd)PNIPAAm-PDLA showed excellent cell viability, and furthermore, Au@PLLA-PEG@PNIPAAmPDLA, particularly at high doses, exhibited more enhanced cell viability than PLLA-PEGCa)PNTPAAm-PDLA. This effect is mainly attributed to the gold layer which binds the protein molecules first and consequently facilitates transmembrane uptake of essential nutrients in the cell media, resulting in favorable cell proliferation.

  • 199.
    Qiu, Ping
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Evolution of corrosion products and metal release from Galvalume coatings on steel during short and long-term atmospheric exposures2012In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 133, no 1, p. 419-428Article in journal (Refereed)
    Abstract [en]

    Non-treated Galvalume (55% Al, 43.4% Zn and 1.6% Si by weight) coatings have been studied through a combination of surface, near surface and bulk analysis after exposure at marine conditions, and for comparison also in an urban test site and in successively more complex short-term laboratory exposures. Slightly polished Galvalume surfaces exhibit dendritic aluminum-rich areas with higher Volta potential compared with interdendritic zinc-rich areas. These effects were not observed on bare as-received surfaces due to the overall presence of aluminum oxide. As a result, preferential corrosion occurred initially in interdendritic areas. The zinc release rate followed the same time-dependence as the surface coverage of zinc-containing phases at the marine exposure condition with zinc predominantly released compared to aluminum. Short term laboratory exposures generated the same main phases as formed at marine conditions. This confirms that the evolution of corrosion products and time dependence of zinc release rates can be explained by the uniform formation of less soluble Al2O3, AlOOH and Al(OH)(3) compared to observed zinc-containing phases, e.g. ZnO, zinc hydroxycarbonate and zinc hydroxychloride. The same underlying mechanism is believed to operate also during exposure of Galvalume in the urban site studied.

  • 200.
    Rafiee, Sepideh
    KTH, School of Chemical Science and Engineering (CHE).
    En jämförelse av biskikt bildade av en geminitensid och en konventionell tensid2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this study was to perform the distinction of the quality and structure of the bilayers created, by operating alternative surfactants in different compositions and concentrations. Previous researches presents that aggregations start to be formed in less than CMC (critical micelle concentration), but bilayers also seem to be created in even lower concentrations. In this experiment the compositions and concentrations which avail the achievement of bilayers were investigated. Surface tensiometer was employed to do the measurments.

    The bilayers were formed in this work are vesicles which are sort of spherical bilayers AKA liposomes and they are the reason which caused the bluish color of the aqueous solutions. Other kinds like discs are not able to result the bluish color, so the hypothesis in this study was having vesicles in the solutions were made by surfactants.

    The experiment was started by measuring surface tension of a mixture of SOS (sodium n-ctyl sulphate) plus DTAB (Dodecyltrimethylammonium) in DI water, from the a higher composition percentage of SOS and a lower composition percentage of DTAB. The procedure was continued by decreaasing in SOS composition and increasing in DTAB composition alternatively. All sets were repeated in identical concentrations from high to low. Bilayers in blue colors were possible to be recognized in lower than CMC in all sets. ST in all samples were measured.

    In the next step the experiment repeated with the same material but in NaBr (50mM) solution instead of water. This time more sets were made and again measured by surface tensiometer. A pattern almost like the previous test was performed, but the solubility was much better in NaBr solution as expected and also bilayers were expected to be formed in higher concentrations.

    The last sets were created for Gemini surfactants with the spacer of 6 and 3 and were measured by surface tensiometer. But muck lower solubility were identified, instead a much more huge aggregation was collected in all sets, both in DI water and NaBr solution.

    Plotting the surface tension measurement (γ) vs. the Ln of concentrations of all sets confirms the investigation that surface tension almost remains the same over CMC, and CMC is the lowest concentration that free surfactants exist and below CMC all surfactants get to create aggregations. Also forming of bilayers happens as decreasing the concentration much better and it does not much depend on the composition.

123456 151 - 200 of 288
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf