The Method of Angular Line to Calculate Eigenvalues for Microstrip Antennas

The method of angular line (MAL) is presented for calculating the resonant frequency of microstrip antenna, which is available in other literature and originally used to analyze various waveguide structure. The results obtained by using this method are in conformity with those reported elsewhere.     

About the pKa of the active-site histidine in flavocytochrome b2 (yeast L-lactate dehydrogenase)

Flavocytochrome b2 or L-lactate dehydrogenase from yeasts catalyzes the oxidation of L-lactate at the expense of monoelectronic acceptors such as cytochrome c, its physiological partner. When incubated in the presence of both L-lactate and a keto acid, the enzyme catalyzes a transhydrogenation reaction wherein only the flavin is involved. During this reaction, the substrate alpha-hydrogen is transferred not only to the solvent but also in part to the keto acid, which acts as reverse substrate. Thus, when bound to the reduced enzyme, this hydrogen is sticky. In the context of a carbanion mechanism, it resides on Nepsilon of His373, the active site base. We have shown before that a correlation between the amount of intermolecular hydrogen transfer from [2-3H] lactate and the keto acid reverse substrate concentration enables the determination of the first-order rate constant, kHe, for exchange of the substrate-derived protein-bound hydrogen with bulk solvent (Urban P, Lederer F, 1985, J Biol Chem 260:11115-11122). In this work, we show that the exchange with the solvent appears to be independent of the phosphate buffer concentration in the range from 40 to 500 mM. It is thus probable that exchange occurs directly with water molecules. The second-order rate constant for exchange is then 0.16 (+/-0.03) M(-1) s(-1). Using the Eigen equation, this figure yields a pKa of 9.1+/-0.1 for His373 in the reduced enzyme, compared to a probable value of 6.0 or less in the oxidized enzyme (Suzuki H, Ogura YC, 1970, J Biochem 67:291-295). The mechanistic significance of these results is discussed.     

On the stabilization of a cable with a tip mass

In this note, we consider a vertical cable which is pinched at the upper end. A mass is attached at the lower end where a control force is also applied. We show that this hybrid system is uniformly stabilized by choosing a suitable control law for the control force depending on the velocity and angular velocity at the free end. Moreover for specific values of the feedback coefficients, we obtain the rate of decay of the energy of the system     

Grafting of glycidylmethacrylate onto demineralized xenogeneic bone in aqueous medium

Summary Demineralized xenogeneic bone (DXB) was prepared from bovine cortical tibia and graft copolymerized with glycidylmethacrylate (GMA) using a combination of potassium persulfate (K₂S₂0₈) and sodium metabisulfite (Na₂S₂O₅)as redox initiating system in aqueous medium. To optimize the reaction condition, the concentrations of backbone, monomer, initiator, temperature and time were varied. The percent grafting was found to increase initially and thereafter decrease in most of the cases. The optimum temperature and time were found to be 40°C and 180 minutes, respectively. The grafting results have been discussed and a reaction mechanism is proposed. Functional groups and structural changes of the graft copolymer were determined by Fourier transform infrared (FT-IR) spectroscopic method for proof of grafting and the results are discussed. Received: 12 August 2002/Revised version: 30 October 2002/ Accepted: 25 November 2002 Correspondence to R. Murugan     

Effect of Covers for Soil and Water Conservation Using Tilting Flume

The effect of stone and vegetative covers was evaluated for soil and water conservation in a waterway on alfisols. Experiments were conducted on a hydraulic tilting flume under simulated flow (93 and 40 cm2?s?1) and slope (0.1, 1.0, 3.0, and 5.0%) conditions. The depth of soil was maintained at 0.35 m over a perforated bed to facilitate deep drainage. A comparative study of bare soil, stone cover (50%), and vegetative cover (50%) is made to evaluate soil loss, deep drainage, Manning’s roughness coefficient, and the Froude number. The study has revealed that stone cover is more effective than vegetative cover at lower discharge in reducing the flow velocity, and thereby soil erosion. Deep drainage has been reduced from lower to higher discharge for all the slopes with cover measures, including bare soil. It is found that cover measures are necessary beyond 3% slope in order to prevent rill erosion in alfisols.     

Type, extent and use of colours in ready-to-eat (RTE) foods prepared in the non-industrial sector – a case study from Hyderabad, India

The type and extent of colours added to ready‐to‐eat (RTE) foods prepared in the non‐industrial sector of India was investigated. Of the 545 RTE foods analysed, 90% contained permitted colours, 2% contained a combination of permitted and non‐permitted colours and 8% contained only non‐permitted colours. However in RTE foods with permitted colours, 73% exceeded 100 ppm, as prescribed by the Prevention of Food Adulteration Act of India, and 27% were within the prescribed levels. Among the permitted colours, tartrazine was the most widely used colour followed by sunset yellow. The maximum concentration of colours was detected in sweet meats (18 767 ppm), non‐alcoholic beverages (9450 ppm), miscellaneous foods (6106 ppm) and hard‐boiled sugar confectioneries (3811 ppm). Among the non‐permitted colours found, rhodamine was most commonly used. Some of the foods, such as savouries and miscellaneous foods like sugar coated aniseed and almond milk, are not supposed to contain colours as per the Prevention of Food Adulteration Act, but were found to contain colours.     

Structure-composition-property dependence in reactive magnetron sputtered ZnO thin films

Thin films of zinc oxide (ZnO) were prepared by dc reactive magnetron sputtering on glass substrates at various oxygen partial pressures in the range 1×10⁻⁴–6×10⁻³ mbar and substrate temperatures in the range 548–723 K. The variation of cathode potential of zinc target on the oxygen partial pressure was explained in terms of target poisoning effects. The stoichiometry of the films has improved with the increase in the oxygen partial pressure. The films were polycrystalline with wurtzite structure. The films formed at higher substrate temperatures were (0 0 2) oriented. The temperature dependence of Hall mobility of the films formed at various substrate temperatures indicated that the grain boundary scattering of charge carriers was predominant electrical conduction mechanism in these films. The optical band gap of the films increased with the increase of substrate temperature. The ZnO films formed under optimized oxygen partial pressure of 1×10⁻³ mbar and substrate temperature of 663 K exhibited low electrical resistivity of 6.9×10⁻² Ω cm, high visible optical transmittance of 83%, optical band gap of 3.28 eV and a figure of merit of 78 Ω⁻¹ cm⁻¹.     

防爆起重机制动器的故障分析及技术改造

防爆起重机是某施工工地用于大型设备的卸车、安装、调试、对接等作业的关键设备。该起重机具有结构复杂，所处环境恶劣，维护保养难度大等特点。制动装置是该设备的关键部件，其可靠性直接关系到吊装工作的安全。在近5年的使用期间，该防爆起重机制动器共出现故障26次，占吊装设备故障总量的56．6％。制动器出现故障的主要部位是制动器线圈、整流模块和摩擦片3部分，其中最易出问题的是整流模块和制动器线圈。为此，对起重机的制动器进行了技术改造。     

Gaussianization: An Efficient Multivariate Density Estimation Technique for Statistical Signal Processing

Multivariate density estimation is an important problem that is frequently encountered in statistical learning and signal processing. One of the most popular techniques is Parzen windowing, also referred to as kernel density estimation. Gaussianization is a procedure that allows one to estimate multivariate densities efficiently from the marginal densities of the individual random variables. In this paper, we present an optimal density estimation scheme that combines the desirable properties of Parzen windowing and Gaussianization, using minimum Kullback–Leibler divergence as the optimality criterion for selecting the kernel size in the Parzen windowing step. The utility of the estimate is illustrated in classifier design, independent components analysis, and Prices’ theorem.