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91.
The crystal structure of alunite (K0.72,Na0.28) Al3(SO4)2(OH)6 from El Gnater, central Tunisia, is refined by the Rietveld method. Raman and infrared data of this mineral are also given in order to provide some further information about the mineralogy and chemistry of this alunite. The crystal system is trigonal, space group R $ \bar 3 The crystal structure of alunite (K0.72,Na0.28) Al3(SO4)2(OH)6 from El Gnater, central Tunisia, is refined by the Rietveld method. Raman and infrared data of this mineral are also given
in order to provide some further information about the mineralogy and chemistry of this alunite. The crystal system is trigonal,
space group R
m, with a = 6.9834(4) ? and c = 17.0899(11) ?. Final Rietveld refinement converges to R
p = 0.16, R
wp = 0.16, and R
Bragg = 0.07. In the alkalic site, the occupancy of potassium and sodium is refined to 72 and 28%, respectively. The Raman and
infrared spectra are investigated in order to improve previous assignments of the observed frequencies, especially for tetrahedral
and octahedral vibration and OH group, which are discussed on the basis of unit-cell group analysis and by comparison with
previously observed wavenumbers of natrojarosite and synthetic alunite.
The text was submitted by the authors in English. 相似文献
92.
Electrode-supported hydrogels were conferred with the biospecificity of enzymes during the process of electropolymerization
to give rise to a class of bioactive, stimuli-responsive co-joined interpenetrating networks of inherently conductive polymers
and highly hydrated hydrogels. Glucose responsive biotransducers were prepared by potentiostatic electropolymerization [750 mV
vs. Ag/AgCl (3 M KCl)] of pyrrole at Poly(hydoxyethyl methacrylate)-based hydrogel-coated Pt micro-electrodes (Φ = 100 μm) from aqueous solutions of pyrrole and glucose oxidase (GOx; 0.4 M pyrrole, 1.0 mg/ml GOx) to 1.0 and 10.0 mC/cm2. Polypyrrole was them over-oxidized by cyclic voltammetry (0–1.2 V vs. Ag/AgCl, 40 cycles in PBKCl, pH = 7.0). Biotransducers
were stored at 4 °C in PBKCl for up to 18 days. Amperometric dose–response at 0.4 V vs. Ag/AgCl followed by Lineweaver–Burk
analysis produced enzyme kinetic parameters as a function of electropolymerization charge density and storage time. Apparent
Michaelis constant (K
Mapp) increased from 18.6–152.0 mM (1.0 mC/cm2) and from 2.7–6.1 mM (10.0 mC/cm2). Biotransducer sensitivity increased to 21.2 nA/mM after 18 days and to 12.8 pA/mM after 10 days for the 1.0 and 10.0 mC/cm2 membranes, respectively. Maximum current, I
max, also increased over time to 2.7 nA (1.0 mC/cm2) and to 170 pA (10.0 mC/cm2). Electropolymerization of polypyrrole is shown to be an effective means for imparting bioactivity to a hydrogel-coated microelectrode.
GOx was shown to be stabilized and to increase activity over time within the electroconductive hydrogel. 相似文献
93.
Yi Yang Renhe Tang Dr. Seifallah Abid Lhoussain Khrouz Dr. Julien C. Vantourout Dr. Anis Tlili 《European journal of organic chemistry》2023,26(36):e202300619
We report the photocatalyzed C−SCF3 bond formation using a new shelf-stable PhPh-N-(SCF3)(CF3) reagent I in combination with 4CzIPN as organophotocatalyst under blue LED irradiation. While the synthesis of vinyl-SCF3 is performed in the presence of bromide salts as an activator of reagent I , the synthesis of trifluoromethylthioesters was undertaken using aldehydes as starting material in the presence of a hydrogen atom transfer catalyst (HAT). Preliminary mechanistic investigations including EPR spectroscopy and cyclic voltammetry analysis shed the light on the reaction mechanisms. 相似文献