湿化学法制备硅纳米线阵列及其光电化学产氢性能分析

为了探究不同方法条件下制备的硅纳米线阵列电极产氢性能异同,文中分别采用了两步金属辅助催化无电刻蚀法、一步金属辅助催化无电刻蚀法以及阳极氧化法来制备硅纳米线阵列用作为光电分解水电池光阴极材料。通过FESEM、XRD和UVVis-IR DRS等手段对实验样品的形貌、晶型、减反性表征,发现相比于其他2种方法所得硅纳米线样品,两步金属辅助催化无电刻蚀法制备的硅纳米线结构晶型保持更好,表面缺陷更少。光电化学测试表明两步金属辅助催化无电刻蚀法制备的硅纳米线光电化学性能表现最优,其光电流密度值是一步法的4倍,阳极氧化法的40倍;转移电荷电阻仅是一步法制备的硅纳米线阵列阻值的1/3,阳极氧化法制备的1/1 000。     

Akt is involved in the inhibition of cell proliferation by EGF

Axin is a negative regulator of the Wnt/beta-catenin pathway and is involved in the regulation of axis formation and proliferation. Involvement of Axin in the regulation of other signaling pathways is poorly understood. In this study, we investigated the involvement of Akt in growth regulation by Axin in L929 fibroblasts stimulated by EGF. Akt activity was increased by EGF treatment and Ras activation, respectively. Both the EGF- and Ras-induced Akt activations were abolished by Axin induction, as revealed by both Western blot and immunocytochemical analyses. The proliferation and Akt activation induced by EGF were decreased by Axin induction, and the effects of EGF were abolished by treatment of an Akt-specific inhibitor. Therefore, Axin inhibits EGF-induced proliferation of L929 fibroblasts by blocking Akt activation.     

Electrocatalysis by ad-atoms: Part XVII. Electronegativity effect on oxygen donation by oxygen-adsorbing ad-atoms and steric hindrance by alkyl groups in Shole control in aldehyde oxidation

The oxidation of propionaldehyde was examined on electrodes modified by Ru, Ag, Hg, Ge, Sn, As, Sb, Bi, S, Se and Te ad-atoms. The feature of the enhancement of propionaldehyde oxidation by ad-atoms was found to be quite similar to that of formaldehyde and acetaldehyde oxidation. The oxidation was found to be enhanced strikingly by oxygen donation by oxygen-adsorbing ad-atoms as well as by the inhibition of poison formation by S_hole control by non-oxygen-adsorbing ad-atoms, but to a lesser extent. In the enhancement by S_hole control, steric hindrance by alkyl groups is observed. In the enhancement by oxygen-adsorbing ad-atoms, the difficulty in oxygen donation from ad-atoms to aldehyde molecules depends on the size of the alkyl group: the smaller the electronegativity of the oxygen-adsorbing ad-atoms, the more difficult is this donation. The donation is discouraged by the orientation of aldehyde molecules caused by the induced negative charge of adsorbed oxygen atoms.     

Fermented Oyster Extract Attenuated Dexamethasone-Induced Muscle Atrophy by Decreasing Oxidative Stress

It is well known that oxidative stress induces muscle atrophy, which decreases with the activation of Nrf2/HO-1. Fermented oyster extracts (FO), rich in γ-aminobutyric acid (GABA) and lactate, have shown antioxidative effects. We evaluated whether FO decreased oxidative stress by upregulating Nrf2/HO-1 and whether it decreased NF-κB, leading to decreased IL-6 and TNF-α. Decreased oxidative stress led to the downregulation of Cbl-b ubiquitin ligase, which increased IGF-1 and decreased FoxO3, atrogin1, and Murf1, and eventually decreased muscle atrophy in dexamethasone (Dexa)-induced muscle atrophy animal model. For four weeks, mice were orally administered with FO, GABA, lactate, or GABA+Lactate, and then Dexa was subcutaneously injected for ten days. During Dexa injection period, FO, GABA, lactate, or GABA+Lactate were also administered, and grip strength test and muscle harvesting were performed on the day of the last Dexa injection. We compared the attenuation effect of FO with GABA, lactate, and GABA+lactate treatment. Nrf2 and HO-1 expressions were increased by Dexa but decreased by FO; SOD activity and glutathione levels were decreased by Dexa but increased by FO; NADPH oxidase activity was increased by Dexa but decreased by FO; NF-κB, IL-6, and TNF-α activities were increased by Dexa were decreased by FO; Cbl-b expression was increased by Dexa but restored by FO; IGF-1 expression was decreased by Dexa but increased by FO; FoxO3, Atrogin-1, and MuRF1 expressions were increased by Dexa but decreased by FO. The gastrocnemius thickness and weight were decreased by Dexa but increased by FO. The cross-sectional area of muscle fiber and grip strength were decreased by Dexa but increased by FO. In conclusion, FO decreased Dexa-induced oxidative stress through the upregulation of Nrf2/HO-1. Decreased oxidative stress led to decreased Cbl-b, FoxO3, atrogin1, and MuRF1, which attenuated muscle atrophy.     

湿化学法制备硅纳米线阵列及其光电化学产氢性能分析

为了探究不同方法条件下制备的硅纳米线阵列电极产氢性能异同,文中分别采用了两步金属辅助催化无电刻蚀法、一步金属辅助催化无电刻蚀法以及阳极氧化法来制备硅纳米线阵列用作为光电分解水电池光阴极材料.通过FESEM、XRD和UV-Vis-IRDRS等手段对实验样品的形貌、晶型、减反性表征,发现相比于其他2种方法所得硅纳米线样品,两步金属辅助催化无电刻蚀法制备的硅纳米线结构晶型保持更好,表面缺陷更少.光电化学测试表明两步金属辅助催化无电刻蚀法制备的硅纳米线光电化学性能表现最优,其光电流密度值是一步法的4倍,阳极氧化法的40倍;转移电荷电阻仅是一步法制备的硅纳米线阵列阻值的1/3,阳极氧化法制备的1/1000.     

Friedel-Crafts Polymers. 6. Friedel-Crafts Polycondensation of p-Xylylerte Dibromide with Salicylic Acid and β-Resorcyiic Acid

Polymers were prepared by condensing p-xylylene dibromide separately with salicylic acid and β-resorcylic acid in the presence of anhydrous ferric chloride in dioxane. The polymer samples_were characterized by elemental analysis, by IR spectral study, by M determined by vapor pressure osmometry, by nonaqueous conducto-metric titration in pyridine, by TGA in air, and by viscosity measurements of polymer solutions in DMF. Polymeric metal chelates of Cu²⁺, Co²⁺, Zn²⁺, Ni²⁺, and Fe³⁺ with polymer samples were prepared and characterized by elemental analysis, by IR spectral study, and by TGA in air. The chelation ion-exchange properties of the polymer samples were studied by employing the batch equilibration method.     

Substoichiometric determination of phosphorus

Phosphorus in orchard leaves (NBS SRM-1571) and spinach (SRM-1570) was determined by various substoichiometric analytical methods such as the direct method, GRASHCHENKO's method and the method of carrier amount variation. All samples were labelled with³²P radioisotope. The data obtained by the method of carrier amount variation were also treated by the method of least squares instead of De VOE's method. Phosphorus concentration in orchard leaves was 0.206±0.011% by the direct method, 0.219±0.011% by GRASHCHENKO's method, 0.211±0.011% by the method of carrier amount variation and 0.207±0.007% by the method of least squares, respectively. These values agree with the value reported by NBS (0.21±0.01%). Furthermore, these concentrations obtained by various substoichiometric methods were compared with those by radioactivation reported in a prevoius paper.     

Comparison of monolithic approaches for enantioselective capillary electrochromatography involving cyclodextrins

The access to CD-modified monoliths for enantiomeric separation by CEC can be divided into two main approaches. (i) Silica-based monoliths, prepared by either a sol-gel process or by sintering of silica particles, are modified after fabrication by coating with a CD selector. Alternatively the fusion of CD functionalized silica particle via gluing is feasible. (ii) Rigid or homogeneous organic polymer-based monoliths, prepared by polymerization of organic monomers in the presence of a porogen, are modified with the CD selector either by copolymerization or by physical incorporation into the continuous bed.     

锰离子控制掺杂二氧化钛薄膜光催化活性增强的机理探讨

采用溶胶-凝胶法通过工艺控制制备了锰离子以不同形式掺杂TiO₂的光催化剂薄膜,并通过XPS和SEM对薄膜的结构进行表征.通过UV-Vis分光光度计及电化学工作站表征了薄膜的光吸收性能和光电化学性能,通过甲基橙溶液的光催化降解脱色率来表征催化剂薄膜的光催化活性.结果表明,以锰离子MT掺杂方式制备的TiO₂薄膜可明显增强TiO₂的光催化活性,而以MM掺杂方式制备的TiO₂薄膜反而降低了TiO₂的光催化活性;锰离子MT掺杂方式的最佳掺杂质量分数为0.8%.催化剂薄膜的电化学行为显示,薄膜具有p-n结的电容-电压特性,锰离子MT掺杂TiO₂薄膜的开路电位和瞬时光电流信号较强,说明其光生载流子易于生成并且分离效果较好.依据半导体的p-n结原理探讨了锰离子控制掺杂TiO₂的光催化活性机理.     

Determination of Mg, Ti and Cl in Ziegler-Natta catalysts by WDXRF

A method for determination of Mg, Ti and Cl in Ziegler-Natta (ZN) catalysts by wavelength dispersive X-ray fluorescence (WDXRF) spectrometry was developed. For comparative reasons, Ti was determined by spectrophotometry, Mg by complexometry and Cl by argentometric titration. Direct pressing was shown to be unsuitable for sample preparation due to catalyst decomposition. For Ti and Mg measurements, catalyst samples were calcinated at 1000 °C and pressed at 275 MPa. Their determination by the fundamental parameters based on the Ti Ka line measurement was shown to be equivalent to those results obtained by univariate calibration or by the classical methods. Cl was determined by aqueous extraction, followed by deposition on a support. Chloride loss was observed. Fixation of Cl as AgCl on polytetrafluoroethylene (FHLC) millipore membrane afforded the best results. Nevertheless, measurements by WDXRF were shown to be inferior to those obtained by argentometric titration.     

New designer drug 2,5-dimethoxy-4-ethylthio-beta-phenethylamine (2C-T-2): studies on its metabolism and toxicological detection in rat urine using gas chromatography/mass spectrometry

Studies are described on the metabolism and the toxicological analysis of the phenethylamine-derived designer drug 2,5-dimethoxy-4-ethylthio-beta-phenethylamine (2C-T-2) in rat urine using gas chromatography/mass spectrometry (GC/MS) after enzymatic cleavage of conjugates, liquid-liquid extraction and derivatization. The structures of 14 metabolites were assigned tentatively by detailed interpretation of their mass spectra. Identification of these metabolites indicated that 2C-T-2 was metabolized by sulfoxidation followed by N-acetylation and either hydroxylation of the S-ethyl side chain or demethylation of one methoxy group, O-demethylation of the parent compound followed by N-acetylation and sulfoxidation, deamination followed by reduction to the corresponding alcohol followed by partial glucuronidation and/or sulfation or by oxidation to the corresponding acid followed either by partial glucuronidation or by degradation to the corresponding benzoic acid derivative followed by partial glucuronidation. Furthermore, 2C-T-2 was metabolized by N-acetylation of the parent compound followed either by O-demethylation and sulfoxidation or by S-dealkylation, S-methylation and sulfoxidation. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction microwave-assisted acetylation allowed the detection of an intake of a dose of 2C-T-2 in rat urine, which corresponds to a common drug users' dose. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of 2C-T-2 in human urine.     

Synthesis, properties, and applications of urethane-modified acrylated poly(ester-amide)s

Epoxy resin-based unsaturated poly(ester-amide) resins (UPEAs) were treated with acryloyl chloride to afford acrylated UPEAs resins (AUPEAs). Urethane-based acrylated poly(ester-amide)s prepared by reaction with diisocyanate were characterized by elemental analysis, by molecular weight determination (by vapour pressure osmometry), by IR spectral study, and by thermogravimetry. The curing of interacting blends was monitored by differential scanning calorimetry (DSC). On the basis of DSC data in-situ glass-reinforced composites were prepared from the resulting materials and their mechanical, electrical, and chemical properties were characterized. Unreinforced blends were characterized by thermogravimetry.     

Kinetic studies of free-radical polymerizations of I-vinylimidazole initiated by benzoyl peroxide and azoisobutyronitrile

Kinetic features of radical polymerizations of 1-vinylimidazole initiated by azoisobutyronitrile and by benzoyl peroxide have been investigated in several solvents and at several temperatures. Polymerizations initiated both by the azo compound and by the peroxide have abnormally low monomer exponents and abnormally high initiator exponents, features first noted by Bamford and Schofield and attributed by them to degradative addition of monomer. Polymerizations initiated by benzoyl peroxide appear to be further complicated by induced decomposition of the initiator; conversion vs time curves, especially for polymerizations in dimethylformamide and particularly at 80°C, show pronounced curvature. These curves can be approximately interpreted in terms of the Tobolsky theory of “dead-end” radical polymerization.     

Oxidations and reductions of iron-cyanogen compounds of cobalt,nickel, cadmium and zinc

I. Cobalt ferrocyanide is oxidized by bromine water, by nitrous acid or by hydrogen peroxide in presence of acids to cobalt ferroferricyanide (cobalt Prussian blue), while cobalt ferricyanide is reduced by sulfurous acid to cobalt Prussian blue.II. Nickel ferrocyanide is oxidized by nitrous acid or by hydrogen peroxide in presence of acids to nickel ferricyanide.III. Nickel ferrocyanide and cadmium ferrocyanide are oxidized by bromine water to the ferricyanides.IV. The ferricyanides of nickel, cadmium and zinc are reduced by sulfurous acid to the ferrocyanides.     

铂修饰光阴极及其在纳晶太阳能电池中的应用

分别用真空镀膜法、热分解法和电化学法制备了铂金修饰导电玻璃,并以此作为光阴极组装了染料敏化纳晶TiO₂太阳能电池.用SEM观察了铂金修饰导电玻璃表面形貌,发现用真空镀膜法制备的铂金膜结构缺陷多、不均匀,存在较多的污点.用热分解法制备的铂金膜具有多孔状结构,但存在较多的有机物分解的残留物.用电镀法制备的铂金膜结构均匀、排列规则、缺陷少、污染少.测定了所制备铂金膜的电阻,结果表明由电镀法所制得的铂金膜电阻最小,用热解法和真空镀膜法制得的铂金膜电阻较大.测定了DSSC电池的光电性能,发现用电镀法制得的铂金膜的催化性能最好,大大提高了DSSC电池的性能;其次是热分解法,由真空镀膜法制备的铂金膜对电池的性能没有多大改善.     

PHOTOINACTIVATION OF SPINACH NITRATE REDUCTASE SENSITIZED BY FLAVIN MONONUCLEOTIDE. EVIDENCE FOR THE INVOLVEMENT OF SINGLET OXYGEN

Abstract All the activities of the nitrate reductase complex from spinach are irreversibly inactivated by irradiation of the enzyme with blue light in the presence of flavin mononucleotide. The photoinactivation requires oxygen and is prevented by ethylenediaminetetraacetic acid and by reduced nicotinamide adenine dinucleotide, but not by superoxide dismutase plus catalase. On the other hand, the inactivation is markedly enhanced in 77% deuterated water and it is suppressed by the singlet oxygen quenchers azide, histidine and tryptophan. All these results suggest that singlet oxygen generated by light absorption by flavin mononucleotide, rather than excited flavin mononucleotide or other oxygen species, is the primary agent involved in the photooxidative inactivation of the enzyme.     

Role of binding entropy in the refinement of protein-ligand docking predictions: analysis based on the use of 11 scoring functions

We present results of testing the ability of eleven popular scoring functions to predict native docked positions using a recently developed method (Ruvinsky and Kozintsev, J Comput Chem 2005, 26, 1089) for estimation the entropy contributions of relative motions to protein-ligand binding affinity. The method is based on the integration of the configurational integral over clusters obtained from multiple docked positions. We use a test set of 100 PDB protein-ligand complexes and ensembles of 101 docked positions generated by (Wang et al. J Med Chem 2003, 46, 2287) for each ligand in the test set. To test the suggested method we compared the averaged root-mean square deviations (RMSD) of the top-scored ligand docked positions, accounting and not accounting for entropy contributions, relative to the experimentally determined positions. We demonstrate that the method increases docking accuracy by 10-21% when used in conjunction with the AutoDock scoring function, by 2-25% with G-Score, by 7-41% with D-Score, by 0-8% with LigScore, by 1-6% with PLP, by 0-12% with LUDI, by 2-8% with F-Score, by 7-29% with ChemScore, by 0-9% with X-Score, by 2-19% with PMF, and by 1-7% with DrugScore. We also compared the performance of the suggested method with the method based on ranking by cluster occupancy only. We analyze how the choice of a clustering-RMSD and a low bound of dense clusters impacts on docking accuracy of the scoring methods. We derive optimal intervals of the clustering-RMSD for 11 scoring functions.     

镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响

利用盆栽试验,研究了镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响.结果表明,施用镧显著增加了青菜生物量,与对照相比地上部干重提高了5.49%～19.78%,根干重提高了13.51%～51.35%.在低浓度下,随镧浓度的升高,青菜茎叶和根的氮、磷、钾含量逐渐增加,到一定浓度后,随着镧浓度的继续升高,含量反而逐渐降低.镧施入土壤后对脲酶、酸性磷酸酶、转化酶活性表现出刺激作用并随浓度的升高而增强,而对过氧化氢酶活性有轻微的抑制作用,对脱氢酶活性有强烈的抑制作用.     

Relation between melting behavior and physical structure in polymers

The phenomenon of double melting, as manifested by two characteristic endotherms in the melting region on a differential thermal analysis (DTA) scan, has been studied in nylon 66 and polystyrene as a function of sample treatment by annealing or drawing. A variety of techniques were used in these studies including DTA, x-ray diffraction, electron microscopy, and mechanical testing. It is shown that the two endotherms are not caused by a bimodal crystal size distribution, by recrystallization, by orientation changes, or by phase changes. It is proposed that one endotherm is caused by the melting of foldedchain crystals, while the other is due to the melting of less perfect bundle crystals. This view is well supported by the results, especially by the DTA measurements made at different heating rates. Published data on the thermal behavior of annealed and drawn poly(ethylene terephthalate) and on polyethylene crystallized at various pressures may also be explained on this basis if it is allowed that in polyethylene the chains may be more extended.