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91.
熔融碳酸盐燃料电池阳极材料表面改性 总被引:1,自引:0,他引:1
选择铌作为合金化元素,通过氟化物熔盐电化学表面合金化的方法对熔融碳酸盐燃料电池阳极材料镍进行表面改性,改性后的阳极材料的耐蚀性能与电催化性能均得到明显的改善。 相似文献
92.
M. N. Repkova M. I. Meshchaninova T. M. Ivanova N. I. Komarova D. V. Pyshnyi A. G. Venyaminova 《Russian Chemical Bulletin》2002,51(7):1194-1197
A solid-phase H-phosphonate procedure was developed for the synthesis of oligoribonucleotides containing aliphatic amino linkers with different lengths at the N(4) atom of cytosine. The hybridization properties of modified oligoribonucleotides were studied. Thermal stability of the RNA—RNA* and DNA—RNA* duplexes depends on the position of modified cytosine in the chain and the type of the duplex. 相似文献
93.
L. Domka 《Colloid and polymer science》1993,271(11):1091-1099
Calcium carbonates of different degrees of surface hydrophobicity were obtained when sorbic acid or polyoxyethylene glycol were present during the precipitation. In the presence of trace amounts of divalent cations carbonates with high surface hydrophilicity and improved monodisperse character are obtained. Surface modification of the calcium carbonates by several proadhesive compounds can markedly improve the chemical affinity of the carbonates to polymers. Very effective are isostearoyl titanate and two polyoxyethylene compounds. Precipitated calcium carbonates modified with 2 to 3 percent (wt/wt) of isostearoyl titanate increased the tensile strenght of butadiene-styrene rubber by approximately 100%. Polyurethane is only strengthened when 30 wt/wt of a filler are introduced independently of the type proadhesive compounds. The best strength and hysteresis of polyurethanes are obtained with calcium carbonate modified with 2 percent (wt/wt) of polyoxyethylene glycol. 相似文献
94.
C(alpha)-Formylglycine, the catalytic amino acid residue in the active site of sulfatases, is generated by post-translational modification of a cysteine or serine residue. We describe a highly sensitive procedure for the detection of C(alpha)-formylglycine-containing peptides in tryptic digests of sulfatase proteins. The protocol is based on the formation of hydrazone derivatives of C(alpha)-formylglycine-containing peptides when using dinitrophenylhydrazine as a matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The hydrazone derivatives desorb and ionize with high efficiency and can be detected in the sub-femtomole range. The presence of C(alpha)-formylglycine is indicated by a mass increment of 180.13 u, corresponding to the hydrazone moiety, and also by a unique C-terminal fragment ion, characteristic of sulfatases, that becomes prominent in MALDI post-source decay mass spectra of the hydrazone derivatives. 相似文献
95.
96.
A facile and environment friendly approach was developed to graft vinyl acetate (VAc) onto plastic articles in an aqueous solution using tert‐butyl alcohol (TBA) as a compatiblizer and benzoyl peroxide (BPO) as an initiator. In a novel setup, excessive monomer suspended in a water phase, VAc could be conveniently grafted on the model substrate of low‐density polyethylene (LDPE) film and the graft percentage (GP) could be developed up to 7.3%. Reaction temperature could increase GP significantly, while adding monomer over a critical volume did not influence GP. By adding some paradioxybenzene, i.e. 0.06–0.08% in VAc phase, homopolymer PVAc could be avoided practically, while graft polymerization proceeded favorably in aqueous solutions. It was proved by attenuated total reflection‐infrared (ATR‐IR) spectroscopy that grafted VAc was located mainly at the surface of the LDPE film and hydrophilic nature of both grafted and alcoholyzed films were improved via contact angle measurements. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
97.
T. Yasuda T. Okuno M. Miyama H. Yasuda 《Journal of polymer science. Part A, Polymer chemistry》1994,32(10):1829-1837
Plasma treatment of a polymeric surface could involve at least three major mechanisms: (1) direct interaction of reactive species in the low-temperature plasma state with the surface (line of sight irradiation effect), and (2) chemical reactions of plasma-induced reactive species with the surface, and (3) reactions among reactive species and the surface (plasma polymerization). The first and the third effects are considered to be limited to the surfaces which directly contact with plasma (glow). The second effect is not limited to the surfaces that contact with plasma state but can penetrate beyond the plasma zone by diffusion. Using an assembly of fibers, of which only the top layer contacts with plasma (glow), the penetration of chemical changes caused by plasma exposure was investigated. Results indicate that the fluorination effect (incorporation of fluorine-containing moieties on the surface of polymeric substrate) penetrates through a considerable thickness of the assembly of fibers, depending on the porosity (gas permeability) of the system. Chemical reactions of plasma-induced (chemically) reactive but nonpolymerizing species with the substrate fibers seems to predominate. The direct interactions of energetic species, such as ions, electrons, and electronically excited species, with polymeric surfaces seems to play relatively minor roles in the plasma treatment investigated. The major role of plasma, in this case, seems to be creating such chemically reactive species. © 1994 John Wiley & Sons, Inc. 相似文献
98.
The influence of hydroxyapatite modification on the cross-linking of polydimethylsiloxane/HAp composites 总被引:1,自引:0,他引:1
Jovanovic J Adnadjevic B Kicanovic M Uskokovic D 《Colloids and surfaces. B, Biointerfaces》2004,39(4):1273-186
Hydroxyapatite (HAp) was modified by the action of various hydrophobic agents based on silicon-containing compounds. The influence of the type of applied agent on the thermodynamic and kinetic parameters of the cross-linking of poly(dimethyl siloxane)/HAp composites was investigated. All the modified HAp particles became hydrophobic and these samples were used to synthesize the polysiloxane/hydroxyapatite composites (PDMS/HAp). The possible modes of interaction between the hydroxyapatite and hydrophobing agents were discussed. The most probable interaction between hydroxyapatite and the applied hydrophobing agents is hydrogen bonding. PDMS/HAp composites were formed directly in the cell of the DSC and cross-linking was investigated in situ. It was determined that the introduction of hydroxyapatite into polysiloxane matrices changed the enthalpy of cross-linking, as well as the activation energy of cross-linking and reaction order, while the introduction of modified HAp led to thermodynamic and kinetic parameters more similar to those of the cross-linking of unfilled elastomer. 相似文献
99.
三氧化铬超微粒的制备与表征 总被引:8,自引:0,他引:8
我们曾首次报道了Fe_2O_3超微粒溶胶具有大的三阶光学非线性响应,其X~((3))值与商品用的掺杂CdS_(1-x)Se玻璃相近,并对其产生机制进行了初步研究.本文用微乳液法制备了经十二烷基苯磺酸钠(DBS)和硬脂酸(ST)表面修饰的Cr_2O_3超微粒,并用TEM、IR、XPS及紫外可见吸收光谱进行了表征. 相似文献
100.