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291.
Małgorzata Wiśniewska Teresa Urban Agnieszka Nosal-Wiercińska Vladimir I. Zarko Vladimir M. Gun’ko 《Central European Journal of Chemistry》2014,12(4):476-479
The influence of anionic poly(acrylic acid) — PAA addition on the stability of synthesized silica, alumina and mixed silica-alumina suspensions as a function of solution pH was studied. The turbidimetry method was used to monitor the changes of the examined systems stability over time. The calculated stability coefficients enabled estimation of polymer adsorption influence on stability of metal oxide suspension. It was shown that the alumina suspension without the polymer is the most unstable at the pH values 6 and 9, whereas the silica polymer was most unstable at pH 3. PAA with higher molecular weight (240 000) is a relatively effective stabilizer of all investigated adsorbents (except silica at pH 3). These properties of poly(acrylic acid) are highly desirable in many branches of industry (e.g. production of cosmetics, pharmaceuticals, paints) where polymers are widely used as effective stabilizers of colloidal suspensions. 相似文献
292.
Jong Hyun Park Dr. Sahng Ha Lee Gun Su Cha Da Som Choi Dong Heon Nam Jae Hyung Lee Prof. Dr. Jung‐Kul Lee Prof. Dr. Chul‐Ho Yun Prof. Dr. Ki Jun Jeong Prof. Dr. Chan Beum Park 《Angewandte Chemie (International ed. in English)》2015,54(3):969-973
Cytochromes P450 can catalyze various regioselective and stereospecific oxidation reactions of non‐functionalized hydrocarbons. Here, we have designed a novel light‐driven platform for cofactor‐free, whole‐cell P450 photo‐biocatalysis using eosin Y (EY) as a photosensitizer. EY can easily enter into the cytoplasm of Escherichia coli and bind specifically to the heme domain of P450. The catalytic turnover of P450 was mediated through the direct transfer of photoinduced electrons from the photosensitized EY to the P450 heme domain under visible light illumination. The photoactivation of the P450 catalytic cycle in the absence of cofactors and redox partners is successfully conducted using many bacterial P450s (variants of P450 BM3) and human P450s (CYPs 1A1, 1A2, 1B1, 2A6, 2E1, and 3A4) for the bioconversion of different substrates, including marketed drugs (simvastatin, lovastatin, and omeprazole) and a steroid (17β‐estradiol), to demonstrate the general applicability of the light‐driven, cofactor‐free system. 相似文献
293.
Seon Hoon Kim Geum-Yoon Oh Doo Gun Kim Hyun Chul Ki Tae Un Kim Hwe Jong Kim 《Optical and Quantum Electronics》2013,45(7):755-760
We proposed triangular resonator integrated with zinc oxide (ZnO) thin film. With assumption that ZnO thin film grown by low temperature hydrothermal method was placed on the over-cladding of the triangular resonator region, the propagation characteristic was analyzed using 2-D finite-difference time-domain method as a function of refractive index change of ZnO thin film. The wavelength of resonance was shifted about 0.002 nm when the change of refractive index of zinc oxide thin film was 0.01. 相似文献
294.
Soo‐Jin Park Gun‐Young Heo Dong‐Hack Suh 《Journal of polymer science. Part A, Polymer chemistry》2003,41(15):2393-2403
In this work, the latent thermal cationic initiators triphenyl benzyl phosphonium hexafluoroantimonate (TBPH) and benzyl‐2‐methylpyrazinium hexafluoroantimonate (BMPH) were newly synthesized and characterized with IR, 1H NMR, and P NMR spectroscopy. The thermal and mechanical properties of difunctional epoxy [diglycidyl ether of bisphenol A (DGEBA)] resins cured by 1 phr of either TBPH or BMPH were investigated. The DGEBA/TBPH system showed a higher curing temperature and a higher critical stress intensity factor than the epoxy/BMPH system. This could be interpreted in terms of the slow thermal diffusion rate and bulk structure of the four phenyl groups in TBPH. However, the decomposition activation energy derived from the Coats–Redfern method was lower for epoxy/TBPH. This result was probably due to the fact that a broken short‐chain structure was developed by the steric hindrance of TBPH in the difunctional epoxy resin. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2393–2403, 2003 相似文献
295.
Jin Ho Kim Yoon Jeong Do Jin Hwan Park Seong Soo Park Seong Soo Hong Gun Dae Lee 《Reaction Kinetics and Catalysis Letters》2004,83(2):377-383
The hydroxylation of phenol into catechol (CAT) and hydroquinone (HQ) with hydrogen peroxide and TS-1 catalyst was carried
out via both photo- and dark (thermal) reactions. The conversion of phenol and the product ratio of CAT/HQ in the photocatalytic
reaction were higher than those in dark (thermal) reaction.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
296.
Young Gun Ko Dong Hun Shin Ung Su Choi 《Journal of polymer science. Part A, Polymer chemistry》2005,43(6):1238-1247
Field‐emission scanning electron microscopy (FESEM) was used to monitor pinecone‐like Cu(II) crystal growth on polymeric fibers for various growth times. In FESEM images, Cu(II) complexes and Cu(OH)2 crystal growth on poly(acryloamidino ethylene amine) and poly(acryloamidino diethylenediamine) were observed. Up to an elapsed time of 16 min, crystal growth was observed in only one direction. However, after an elapsed time of 20 h, pinecone‐like crystals covered the entire surfaces of the synthesized polymers. Fourier transform infrared spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy were used for analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1238–1247, 2005 相似文献
297.
A mathematical model to describe the pulse shape of delayed adsorbate fluorescence is proposed that accounts for desorption of oxygen molecules from the surface of a substrate induced by interaction with phonons. A numerical study of the temperature dependence of the probability of desorption of oxygen molecules from the substrate surface and of the luminescence intensity is carried out. 相似文献
298.
299.
We find the general form of solutions of the integral equation ∫k(t ? s)u1(s) ds = u2(t) of the convolution type for the pair of unknown functions u1 and u2 in the class of compactly supported continuously differentiable functions under the condition that the kernel k(t) has the Fourier transform \(\widetilde {{P_2}}\), where \(\widetilde {{P_1}}\) and \(\widetilde {{P_2}}\) are polynomials in the exponential eiτx, τ > 0, with coefficients polynomial in x. If the functions \({P_l}\left( x \right) = \widetilde {{P_l}}\left( {{e^{i\tau x}}} \right)\), l = 1, 2, have no common zeros, then the general solution in Fourier transforms has the form Ul(x) = Pl(x)R(x), l = 1, 2, where R(x) is the Fourier transform of an arbitrary compactly supported continuously differentiable function r(t). 相似文献
300.
Lee K Oh SH Kang NG Lee JS Kim DY Lee H Jung GY 《Langmuir : the ACS journal of surfaces and colloids》2008,24(16):8413-8416
Nanoscale metal patterns were successfully reproduced on top of a functional organic layer by a direct metal-transfer technique (DMT). A gold film deposited on the protruding features of a stamp was transferred to the organic layer by controlling its stickiness through a two-step thermal treatment. The process was also suitable for the transfer of highly adhesive metal materials to the stamp surface by using an additional gold layer. Chromium nanowires at 70 nm half-pitch were faithfully produced without any damage to the organic active layer. 相似文献