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101.
V. V. Avdin A. A. Lymar A. V. Batist E. A. Nikitin M. Yu. Belkanova V. A. Potemkin 《Journal of Structural Chemistry》2007,48(4):747-752
Oxyhydrate gels have a hydrophilic surface, due to which they undergo destruction and secondary polymerization in aqueous media. Prolonged storage in aqueous solution gives rise to regions with selfsimilar helical ordering in gels. Structuring of this kind is also observed when synthesis is conducted under conditions that provide low gelation rates. Electromagnetic UV and visible radiation is another means to change the gel structure; it makes the oligomer species pass into the excited state, due to which one of the directions of structuring becomes dominant. This work summarizes the results of computer simulation of gel agglomerates. For oxyhydrate systems, helical ordering was found to be one of the local energy minima. The units of a macrohelix can lie at various angles relative to one another, and they can change, after absorption of energy, the helix pitch and the order of elements in the helix. 相似文献
102.
We synthesized the new photosensitive oligomer containing a chalcone moiety in the main chain by end-capping reaction of diepoxide compound with methacrylic acid. The chalcone-epoxy oligomeric compound was synthesized with 4,4′-dihydroxychalcone and epichlorohydrin. Investigation of the photosensitivity of the newly synthesized chalcone oligomer was carried out by using UV-Vis absorption and infrared spectroscopies under UV exposure. We observed the photodimerization behavior under UV irradiation. At the same time, we could also observe the photopolymerization of the compound with a trace amount of dimethoxyphenyl acetophenone. Thermal properties of UV-cured dimethacrylate compounds were also studied. 相似文献
103.
电感耦合等离子体发射光谱(ICP-AES)测定高纯氧化镧中14个稀土元素杂质,镧对其它稀土元素的光谱干扰比较严重,要求光谱仪单色器有较高的分辨率。使用端视式全谱直读ICP-AES仪,选择测定波长,工作参数优化,讨论了镧和酸度的影响。大部分稀土元素测定使用曲线拟合(FACT)的背景校正方法。该方法的稀土元素氧化物检出限达到3×10-4~0.022 mg.L-1(3σ)。 相似文献
104.
Harald Stueger Markus Braunwarth Gottfried Fuerpass Judith Baumgartner Robert Saf 《Monatshefte für Chemie / Chemical Monthly》2006,137(5):595-603
Summary. The previously unknown ruthenio disilanes Rp–Si2Me4–C6H4X (Rp = η5-C5H5Ru(CO)2; X = H, Br, –CHO, CH=C(CN)2) were synthesized from ClSi2Me4C6H4X (X = H, Br) and Rp− using conventional chemical methods. Trends in the UV/Vis absorption spectra indicate strong electronic coupling within the
Rp–Si–Si–Caryl fragment and, therefore, closely resemble the ones observed for the corresponding iron complexes. The four compounds however,
were shown to be less sensitive towards UV irradiation. The crystal structure of Rp–Si2Me4–C6H4CH=C(CN)2 was determined by X-ray diffraction and exhibits an all-trans-array of the Ru–Si–Si–Caryl moiety, what is a basic requirement for optimal through-bond interaction. 相似文献
105.
本文通过酶活性测定,荧光光谱和紫外光谱研究了外加Cu2+与烟草多酚氧化酶(简称PPO)的相互作用。结果表明,微量铜的加入能增加酶的活性,[Cu2+]/[PPO]为0.20左右时酶活性最大,[Cu2+]/[PPO]为0.91时,Cu2+开始表现出对PPO活性的抑制;Cu2+对PPO内源荧光的猝灭机制属于形成络合物所引起的静态猝灭,猝灭常数Ksv为8.0375×103L·mol-1;Cu2+的加入使PPO蛋白质分子构象发生变化,α-螺旋含量增加,多肽链及Trp和Tyr残基的芳杂环进一步向分子内收缩,疏水基团之间的疏水作用增强。 相似文献
106.
The potential-dependent surface-enhanced Raman spectrum of adsorbed p-nitrobenzoic acid (PNBA) on the roughened Au electrode has been obtained by using ultraviolet (UV) excitation at 325 nm. The surface-enhanced Raman spectra of PNBA intensely changed when the voltage was in the rang of negative value, and the electrode potential at which the resonance (potential of maximum intensity) occurs varied when the vibrational mode changes, indicating that the PNBA molecules were chemisorbed on the roughened Au surface. The charge transfer (CT) mechanism could probably explain the experiment results in the present work. 相似文献
107.
Photocatalysis has been extensively studied due to its potential ability to avoid the excessive use of chemical reagents and reduce the energy consumption by employing solar energy. Moreover, to alleviate the reduction in the membrane permeation selectivity, separation efficiency, and membrane service life caused by the emerging micro-pollutants and membrane fouling, membrane technology is often coupled with microbial, electrochemical, and catalytic processes. However, although physical/chemical cleaning and membrane module replacement can overcome the inherent limitations caused by membrane fouling and other membrane separation processes, high operating costs limit their practical applications. In this review, common preparation methods for TiO2 photocatalytic membranes are described in detail, and the main approaches to enhancing their photocatalytic performance are discussed. More importantly, the mechanism of the TiO2 photocatalytic membrane antifouling process is elucidated, and some applications of photocatalytic membranes in other areas are described. This review systematically outlines future research directions in the field of photocatalytic membrane modification, including metal and non-metal doping, fabrication of heterojunction structures, control over reaction conditions, increase in hydrophilicity, and increase in membrane porosity. 相似文献
108.
UV curable epoxy acrylates were reinforced with two different organically modified montmorillonites (MMTs) and an unmodified MMT. Conversion and rate of polymerization was monitored by real time infrared spectroscopy (RTIR) and photo-DSC. Microstructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical clarity. Optical clarity of the films containing clay was quite good as only a slight decrease was observed. Physical properties of the reinforced films were examined by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), hardness and tensile testing. Enhancements in glass transition temperature (Tg), thermal stability and mechanical properties were observed. The films reinforced with the unmodified MMT exhibit the most significant enhancements in properties. 相似文献
109.
Barbara Szafran Jan Pawlaczyk 《Journal of inclusion phenomena and macrocyclic chemistry》1995,23(4):277-288
The 1 : 1 inclusion complex involving sulfafurazole (SF) and-cyclodextrin (-CD) is prepared by the freeze-drying method and characterized on the basis of its chemical analysis, thermal behavior, infrared spectrum, X-ray powder pattern and13C NMR spectrum in DMSO-d6 solution. The stability constant of the inclusion complex was determined by the solubility method. The effect of cyclodextrin on the UV absorption spectrum of sulfafurazole was also observed. 相似文献
110.
H. Reul 《Fresenius' Journal of Analytical Chemistry》1977,285(2):126