Ti/TiO<Subscript>2</Subscript> nanotube array electrode as a new sensor to photoelectrocatalytic determination of ethylene glycol

The photoelectrocatalytic oxidation behaviour of ethylene glycol (EG) was studied in the present work using the TiO₂-modified Ti foil (Ti/TiO₂) electrode. The Ti/TiO₂ nanotube array (Ti-NTA) electrode was prepared by anodizing of the Ti foil in the HF aqueous solution (0.2% v/v). The anodization was conducted in the constant 30 V for 2 h, and then the as-prepared Ti-NTA electrode was calcinated at 50 ^° C for 2 h. The surface morphology of Ti- NTA electrode was studied using scanning electron microscopy images. For EG determination, the photocurrent of EG (EG oxidation current in the UV irradiation) was assessed using the hydrodynamic photoamperometric method in the phosphate buffers. Ultimately, the optimum conditions of EG determination were studied in various pH values and applied bias potentials, and the pH = 3.0 and E= 1.0 V (vs. reference electrode) were determined as the optimum conditions. It was found that the photocurrent of EG was linearly dependent on the concentration of EG in the range of 3.0 × 10 ^?5 to 0.88 mol l ^?1 , and the detection limit of EG determination was found to be 7.2 × 10^?6 mol l^?1 (3 σ).     

Investigation of superhydrophilic mechanism of titania nano layer thin film—Silica and indium oxide dopant effect

In this paper, TiO₂?CSiO₂?CIn₂O₃ nano layer thin films were deposited on glass substrate using sol?Cgel dip coating method. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements were used to evaluate chemical structure, surface composition, hydroxyl group contents and superhydrophilicity of titania films. FTIR result indicated that Si?CO?CSi, Si?CO?CTi and Ti?CO?CTi bands formed in TiO₂?CSiO₂?CIn₂O₃ sample. According to XPS, the hydroxyl content for TiO₂, TiO₂?CSiO₂ and TiO₂?CSiO₂?CIn₂O₃ films was calculated as 11·6, 17·1 and 20·7%, respectively. The water contact angle measurements indicated that silica and indium oxide dopant improved the superhydrophilicity of titania nano film surface especially in a dark place. The enhanced superhydrophilicity can be related to the generation of surface acidity on the titania nano film surfaces. In the present state, superhydrophilicity is induced by the simultaneous presence of both Lewis and Bronsted sites.     

分光光度法测定维吾尔传统药用植物何首乌的总黄酮含量

以芦丁为对照品，用分光光度法测定何首乌提取物中总黄酮含量。得乙酸乙酯部位的黄酮含量最高，石油醚部位的黄酮含量最低。     

AN ASSESSMENT OF THE HARMONIC POLLUTION DUE TO LINE CORONA

Abstract

This work deals with the phenomenon of corona on high voltage overhead transmission lines as a possible source of harmonic pollution. Starting with a validated method for simulating corona by means of distributed nonlinear shunt resistors, the distorted current waveforms for different locations on a long line could be determined. The location-dependent frequency spectrum of the line longitudinal current could be obtained through numerical Fourier analysis. It is shown, that under some operating and weather conditions, the harmonic content of the line current can attain technically unacceptable values.     

Time Evolution of Demixing in Oxides under an Oxygen Potential Gradient

Time evolution of concentration profiles leading to steady-state demixing in oxides under oxygen partial pressure gradient is treated based on a microscopic model by applying the path probability method of irreversible statistical mechanics. The redistribution of vacancies and cations toward the steady-state distribution has essentially been reduced to the diffusion of vacancies and the interdiffusion of cations along the specimen. Atomistic features of the problem, such as a vast difference in the relaxation times for the redistribution of vacancies and cations, are emphasized. Time required for the system to reach the steady state is then estimated in terms of fundamental material properties.     

Preparation, characterization and photocatalytic activity of TiO2/polyaniline core-shell nanocomposite

Polyaniline (PANI) as a promising conducting polymer has been used to prepare polyaniline/TiO₂ (PANI/TiO₂) nanocomposite with core-shell structure as photocatalyst. Titanium dioxide (TiO₂) nanoparticles with an average crystal size of 21?nm were encapsulated by PANI via the in situ polymerization of aniline on the surface of TiO₂ nanoparticles. FT?CIR, UV-Vis-NIR, XRD, SEM and TEM techniques were used to characterize the PANI/TiO₂ core-shell nanocomposite. Photocatalytic activity of PANI/TiO₂ nanocomposite was investigated under both UV and visible light irradiations and compared with unmodified TiO₂ nanoparticles. Results indicated deposition of PANI on the surface of TiO₂ nanoparticles which improved the photocatalytic activity of pristine TiO₂ nanoparticles.     

Fiscal-period-based service level constraints and safety stock requirements†

This paper deals with service level constraints which are defined over a fiscal period. Fiscal-period-based service level constraints are considerably more complex than their lead-time counterparts and result in significantly different safety stock requirements. Thus, a confusion between a lead-time and fiscal-period perspective can result in substantial financial consequences and is therefore of managerial relevance. Although no generalizations are possible from the limited results presented, further computational experience suggests that the findings reported hold over a wide range of situations.     

Fast-sintering of hydrothermally synthesized BaTiO3 powders and their dielectric properties

Hydrothermally synthesized barium titanate (BaTiO₃) powders with a submicrometre particle size have been fast-sintered with a heating rate of ∼ 200 °C min^-1 at various temperatures (1250–1350 °C) for short times (5 and 15 min). The microstructures and dielectric properties of the sintered samples are studied and compared with those sintered conventionally. The sample fast-sintered at 1250 °C for 5 min had the highest dielectric constant value of approximately 3700 with an average grain size of about 1 μm. Both the dielectric constant and the Curie–Weiss temperature are found to be dependent on the grain size of the sintered samples, particularly when the average grain size is less than 5 μm. This has been attributed to the presence of internal stress in the fine-grained BaTiO₃. This revised version was published online in November 2006 with corrections to the Cover Date.     

新疆石榴花中总黄酮提取工艺研究

石榴花含有黄酮类化合物。本实验采用分光光度法,以芦丁为标准样品,测定石榴花中的总黄酮的含量。结果表明:黄酮类化合物的最佳提取工艺为:乙醇浓度45%,提取时间为1h,料液比1:60,提取温度为60℃。试验结果可能为以后石榴花资源的开发利用提供重要的理论依据。     

琐琐葡萄乙酸乙酯提液和正丁醇提液抑菌作用初步研究

先用95%乙醇浸泡,然后用乙酸乙酯和正丁醇从琐琐葡萄中提取其活性成分,并探讨了其抑菌作用。结果表明,琐琐葡萄乙酸乙酯和正丁醇提取物对微生物有明显抑制作用。