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971.
The molecular structure of Ph3CSSC(S)SCPh3 · CS2 has been determined by X-ray structural analysis. The substance crystallizes in the triclinic crystal system [a = 884.9(2) pm, b = 1 039.5(2) pm, c = 2 064.6(3) pm, α = 75.86(1)°, β = 79.83(2)°, γ = 77.31(5)°, Z = 2, space group P1 ]. The CS3 group is planar; the S? S-bond (201.4 pm) forms an angle of 5.7° with the CS3 plane. The torsional angle CSSC equals 96.3°. (Ph3C)2CS4 was obtained by reaction of TosNSCl2 (Tos = p-MeC6H4SO2) with Ph3CSH in CS2 in the presence of triethylamine. The reaction mechanism is discussed. 相似文献
972.
973.
We report on a new enzyme/support system to immobilize proteins such as enzymes through a covalent bond on polysulfone membranes. In the present case the enzyme endo-1,4-β-xylanase (E.C.3.2.1.8) is attached to polysulfone previously derivatized by introducing an acrylate group. Membranes are properly prepared from this polysulfone acrylate. Afterwards the enzyme is immobilized though the amino groups of side chains of the amino acids of the enzyme and the acrylate group of the derivatized polysulfone. Such immobilization of the enzyme is confirmed by microelemental analysis as well as by amino acid analysis by HPLC. Moreover, the enzymatic activity of the membranes was evaluated and compared with that corresponding to the free enzyme. Certain physical parameters (asymmetry, irregularity, pore size and surface roughness) of the corresponding enzymatic membranes were obtained from SEM and AFM image interpretation. 相似文献
974.
In this work, low pressure glow discharge O2 plasma has been used to increase wettability in a LDPE film in order to improve adhesion properties and make it useful for technical applications. Surface energy values have been estimated using contact angle measurements for different exposure times and different test liquids. In addition, plasma-treated samples have been subjected to an aging process to determine the durability of the plasma treatment. Characterization of the surface changes due to the plasma treatment has been carried out by means of Fourier transformed infrared spectroscopy (FTIR) to determine the presence of polar species such as carbonyl, carboxyl and hydroxyl groups. In addition to this, atomic force microscopy (AFM) analysis has been used to evaluate changes in surface morphology and roughness. Furthermore, and considering the semicrystalline nature of the LDPE film, a calorimetric study using differential scanning calorimetry (DSC) has been carried out to determine changes in crystallinity and degradation temperatures induced by the plasma treatment. The results show that low pressure O2 plasma improves wettability in LDPE films and no significant changes can be observed at longer exposure times. Nevertheless, we can observe that short exposure times to low pressure O2 plasma promote the formation of some polar species on the exposed surface and longer exposure times cause slight abrasion on LDPE films as observed by the little increase in surface roughness. 相似文献
975.
Páez-Hernández ME Aguilar-Arteaga K Valiente M Ramírez-Silva MT Romero-Romo M Palomar-Pardavé M 《Analytical and bioanalytical chemistry》2004,380(4):690-697
The results presented in this work deal with the prime application of activated composite membranes (ACMs) for the transport of Hg(II) ions in a continuous extraction–re-extraction system using di-(2-ethylhexyl)dithiophosphoric acid (DTPA) as carrier. The effects of variables such as the pH, the nature of the acid and the concentration of the casting solutions on the transport of Hg(II) are also investigated. When the ACM was prepared with a 0.5 M DTPA solution and when the feed solution contained 2.5×10–4 M Hg(II) in 0.1 M HCl, the amount of mercury extracted was greater than 76%. The re-extracted mercury was subsequently recovered by means of a stripping phase comprising 0.3 M thiourea solution in 2 M H2SO4, yielding 54% of the initial amount of mercury after transport had taken place for 180 min. 相似文献
976.
977.
978.
Photovoltaic and spectral properties of tetraphenyloporphyrin and metallotetraphenyloporphyrin dyes 总被引:1,自引:0,他引:1
Spectroscopical properties and photocurrent (or photovoltage) of tetraphenyloporphyrins and metallotetraphenyloporphyrins in nematic liquid crystal have been studied. Photoelectric response has been measured in an electrochemical cell made of the semitransparent semiconducting and golden electrodes with porphyrin dyes embedded in liquid crystal. Fluorescence, time-resolved luminescence in microsecond time scale and photoacoustic spectra have also been measured. The competition between radiative, non-radiative processes and charge transfer is discussed. It has been shown that effectivity of porphyrins for photocurrent generation depends on the presence/absence of central metal in the macrocycle of porphyrin skeleton and the kind of metal. The schematic model of the contributions of the dye molecule and semiconducting electrode in the electron transfer process is shown. 相似文献
979.
V. V. Dotsenko S. G. Krivokolysko A. N. Chernega V. P. Litvinov 《Russian Chemical Bulletin》2007,56(7):1431-1436
A new stereoselective method for the synthesis of trans-isomers of 2-amino-4-aryl-5-benzoyl-4,5-dihydrothiophene-3-carbonitriles was proposed. The method involves base-catalyzed
reactions of phenacyl thiocyanate with 3-(het)aryl-2-cyanoprop-2-enethioamides. (4R,5S/4S,5R)-2-Amino-5-benzoyl-4-(2-chlorophenyl)-4,5-ihydrothiophene-3-carbonitrile was structurally characterized by X-ray diffraction
analysis.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1379–1383, July, 2007. 相似文献
980.
Thermal
degradation of vinylidene chloride/[4-(t-butoxycarbonyloxy)phenyl]methyl
acrylate copolymers
B. A. Howell D. A. Spears P. B. Smith 《Journal of Thermal Analysis and Calorimetry》2006,85(1):115-117
Vinylidene chloride polymers containing comonomer
units capable of consuming evolved hydrogen chloride to expose good radical-scavenging
sites might be expected to display greater thermal stability than similar
polymers containing simple alkyl acrylates as comonomer. Incorporation of
a comonomer containing the phenyl t-butyl
carbonate moiety into a vinylidene chloride polymer has the potential to afford
a polymer with pendant groups which might interact with hydrogen chloride
to expose phenolic groups. Copolymers of vinylidene chloride with [4-(t-butoxycarbonyloxy)phenyl]methyl acrylate have been
prepared, characterized, and subjected to thermal degradation. The degradation
has been characterized by thermal and spectroscopic techniques. The degradation
of vinylidene chloride/[4-(t-butoxycarbonyloxy)phenyl]methyl
acrylate copolymers is much more facile than the same process for similar
copolymers containing either [4-(isobutoxycarbonyloxy)phenyl]methyl acrylate
or methyl acrylate, a simple alkyl acrylate, as comonomer. During copolymer
degradation, [4-(t-butoxycarbonyloxy) phenylmethyl
acrylate units are apparently converted to acrylic acid units by extensive
fragmentation of the sidechain. Thus, the phenyl t-butyl
carbonate moiety does function as a labile acid-sensitive pendant group but
its decomposition in this instance leads to the generation of a phenoxybenzyl
carboxylate capable of further fragmentation. 相似文献