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41.
Electroless deposition of a Co?Ni?P alloy on the surface of graphite felt filaments was performed in a low-temperature pyrophosphate solution under flow-through conditions. The loading, composition, morphology, and structure of electroless the Co?Ni?P alloy deposit on the filaments of the modified graphite felt were investigated by gravimetric analysis, energy-dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffraction, respectively. Electrochemical characterization of a graphite felt electrode modified with electroless Co?Ni?P alloy was performed by cyclic voltammetry, chrono-techniques, and the electrochemical impedance spectroscopy test in an aqueous solution of polysulfide composed of the mixture of 1 M Na2S, 1 M NaOH and 1 M S. It was found that the electroless Co?Ni?P alloy deposit on graphite felt has good cycling stability and high electrocatalytic activity toward reversible electrochemical redox reactions of polysulfide species. In comparison with the bare graphite felt electrode, the electrode modified with the electroless Co?Ni?P alloy showed five to seven times lower values of anodic and cathodic overpotentials in the aqueous solution of polysulfide. It is very likely that the good electrochemical performance of the modified graphite felt electrode is related to the high surface area of the electroless Co?Ni?P alloy deposit. 相似文献
42.
Brigita Tomšič Barbara Simončič Boris Orel Lidija Černe Petra Forte Tavčer Mateja Zorko Ivan Jerman Aljaž Vilčnik Janez Kovač 《Journal of Sol-Gel Science and Technology》2008,47(1):44-57
Multifunctional, water and oil repellent and antimicrobial finishes for cotton fibres were prepared from a commercially available
fluoroalkylfunctional water-born siloxane (FAS) (Degussa), nanosized silver (Ag) (CHT) and a reactive organic–inorganic binder
(RB) (CHT). Two different application procedures were used: firstly, one stage treatment of cotton fabric samples by FAS sol
(i), as well as by a sol mixture constituted from all three precursors (Ag–RB–FAS, procedure 1S) (ii), and secondly, two stage
treatment of cotton by Ag–RB sol and than by FAS sol (Ag–RB + FAS, procedure 2S) (iii). The hydrophobic and oleophobic properties
of cotton fabrics treated by procedures (i)–(iii) before and after consecutive (up to 10) washings were established from contact
angle measurements (water, diiodomethane and n-hexadecane) and correlated with infrared and XPS spectroscopic measurements. The results revealed that even after 10 washing
cycles cotton treated with Ag–RB + FAS (2S) retained an oleophobicity similar to that of the FAS treated cotton, while the
Ag–RB–FAS (1S) cotton fibres exhibited a loss of oleophobicity already after the second washing, even though fluorine and
C–F vibrational bands were detected in the corresponding XPS and IR spectra. The antibacterial activity of cotton treated
by procedures (i)–(iii) was tested by its reduction of the bacteria Escherichia coli and Staphylococcus aureus following the AATCC 100-1999 standard method and EN ISO 20743:2007 transfer method. The reduction in growth of both bacteria
was nearly complete for the unwashed Ag–RB and Ag–RB–FAS (S1), but for the unwashed Ag–RB + FAS (S2) treated cotton no reduction
of S. aureus and 43.5 ± 6.9% reduction of E. coli was noted. After the first washing, the latter two finishes exhibited nearly a complete reduction of E. coli but for the Ag–RB treated cotton the reduction dropped to 88.9 ± 3.4. None of the finishes retained antibacterial properties
after 10 repetitive washings. The beneficial and long-lasting low surface energy effect of FAS finishes in the absence of
Ag nanoparticles, which led to the “passive” antibacterial properties of FAS treated cotton fabrics, was established by applying
the EN ISO 20743:2007 transfer method. The results revealed a reduction in bacteria of about 21.9 ± 5.7% (FAS), 13.1 ± 4.8%
(Ag–RB–FAS (S1)) and 41.5 ± 3.7% (Ag–Rb + FAS (S2)), while no reduction of the growth of bacteria was observed for cotton
treated with Ag nanoparticles after 10 repetitive washings. The physical properties (bending rigidity, breaking strength,
air permeability) of finished cotton samples were determined, and showed increased fabric softness and flexibility as compared
to the Ag–RB treated cotton, but a slight decrease of breaking strength in the warp and weft directions, while air permeability
decreased for all type of finishes. 相似文献
43.
Arkadij Sobolev Maurice C R Franssen Brigita Vigante Brigita Cekavicus Raivis Zhalubovskis Huub Kooijman Anthony L Spek Gunars Duburs Aede de Groot 《The Journal of organic chemistry》2002,67(2):401-410
Since 2,6-dimethyl-4-aryl-1,4-dihydropyridine 3,5-diesters themselves are not hydrolyzed by commercially available hydrolases, derivatives with spacers containing a hydrolyzable group were prepared. Seven acyloxymethyl esters of 5-methyl- and 5-(2-propoxyethyl) 4-[2-(difluoromethoxy)phenyl]-2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate were synthesized and subjected to Candida rugosa lipase (CRL) catalyzed hydrolysis in wet diisopropyl ether. A methyl ester at the 5-position and a long or branched acyl chain at C3 gave the highest enantiomeric ratio (E values). The most stereoselective reaction (E = 21) was obtained with 3-[(isobutyryloxy)methyl] 5-methyl 4-(2-difluoromethoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate, and this compound was used to prepare both enantiomers of 3-methyl 5-(2-propoxyethyl) 4-[2-(difluoromethoxy)phenyl]-2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate. The absolute configuration of the enzymatically produced carboxylic acid was established to be 4R by X-ray crystallographic analysis of its 1-(R)-phenylethyl amide. 相似文献
44.
45.
Brigita Tomši?Danijela Klemen?i? Barbara Simon?i? Boris Orel 《Polymer Degradation and Stability》2011,96(7):1286-1296
The influence of antimicrobial activity of two contemporary finishes, specifically a dispersion of colloidal silver (Ag) and 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (Si-QAC), on the degree of biodeterioration of 100% cotton (CO) fabric and fabric composed of a mixture of cotton and polyester (CO/PET) was studied. Ag was chosen for the leaching agent, while Si-QAC was used as the bio-barrier-forming agent. The biodeterioration of samples finished with different concentrations of Ag and Si-QAC was analysed from a standard soil burial test after 3, 6 and 12 days of exposure to soil microflora. SEM micrographs revealed intensive biodeterioration of the unfinished cellulose fibres, while the highly biologically resistant polyester fibres remained undamaged. A controlled release of Ag successfully inhibited biodeterioration of the cellulose fibres in the CO and CO/PET fabrics when its concentration reached a lethal, biocidal concentration. Contrary to the effects of Ag, the bio-barrier formation of Si-QAC on CO and CO/PET fabrics was insufficient to protect the cellulose fibres during longer periods of soil burial, irrespective of its concentration. Intensive chemical changes to the cellulose were clearly seen from the FT-IR spectra of all of the samples. The resistance of the polyester component to biodeterioration did not provide any significant protection for the cotton component in CO/PET fabric. 相似文献
46.
Brigita CekavicusKintija Kore Liva JakoveleAiva Plotniece Karlis PajusteMarina Petrova Sergey BelyakovArkadij Sobolev 《Tetrahedron letters》2011,52(47):6246-6249
Cyclisation of γ-halo-β-ketoesters with aromatic amines and aldehydes in methanol gave novel polysubstituted 3-pyrroline derivatives. A plausible mechanism for the reaction has been proposed. The structures of 1,2,3,4-tetrasubstituted 3-pyrrolines were confirmed by NMR spectroscopy and X-ray crystallography. 相似文献
47.
Brigita Darminto Dr. Gregory J. Rees John Cattermull Dr. Kenjiro Hashi Dr. Maria Diaz-Lopez Dr. Naoaki Kuwata Dr. Stephen J. Turrell Emily Milan Yvonne Chart Dr. Camilla Di Mino Prof. Hyeon Jeong Lee Prof. Andrew L. Goodwin Prof. Mauro Pasta 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314444
The sodium-rich antiperovskites (NaRAPs) with composition Na3OB (B=Br, Cl, I, BH4, etc.) are a family of materials that has recently attracted great interest for application as solid electrolytes in sodium metal batteries. Non-Arrhenius ionic conductivities have been reported for these materials, the origin of which is poorly understood. In this work, we combined temperature-resolved bulk and local characterisation methods to gain an insight into the origin of this unusual behaviour using Na3OBr as a model system. We first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; then identified the presence of a poorly crystalline impurities, not detectable by XRD, and elucidated their effect on ionic conductivity. These findings improve understanding of the processing-structure-properties relationships pertaining to NaRAPs and highlight the need to determine these relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes. 相似文献