Growth and development ofThiobacillus ferrooxidans for engineering applications

A bioprocessing approach for the extraction of base, nuclear and precious metals from refractory and lean grade ores has been reviewed in this paper. Characteristic morphological features ofThiobacillus ferrooxidans, the organism which has been extensively used for biooxidation of sulphide ores have been discussed. Mechanisms of chemoautotrophy and mineral oxidation have been illustrated. The current engineering applications of this microorganism have also been brought out. Various methods for accelerating the growth ofThiobacillus ferrooxidans for faster biooxidation and genetic manipulation for development of desired strains have been outlined.     

Pluronic lecithin organogel of 5-aminosalicylic acid for wound healing

5-Aminosalicylic acid (5-ASA) is an aminosalicylate anti-inflammatory drug, which is also known as mesalazine or mesalamine. Currently employed in treating inflammatory bowel disease, ulcerative colitis, inflamed anus or rectum, and maintain remission in Crohn's disease. Evidence from the researchers highlighted its significant re-epithelization in allergic asthma, aphthous, and gastric ulcerative conditions. The objective of the study was to formulate the pluronic lecithin organogel (PLO) containing 5-ASA and evaluate its wound-healing ability in a full thickness excision wound rat model. The data obtained from in silico docking studies revealed 5-ASA is having an affinity towards the transforming growth factor-beta (TGF-β) specifically towards beta1. Among various formulations prepared (F1 to F8), F1, and F6 have shown a maximum in vitro drug release with optimum pH and viscosity. From MTT assay it was found that selected PLO formulations showed no toxicity and enhanced cell proliferation in HaCaT cell lines. In vivo wound-healing studies in albino Wistar rats has revealed that PLO accelerates wound closure and reepithelization to the statistically significant level on day 3 (p?相似文献   

A simple method to estimate gain-bandwidth product and the secondpole of the operational amplifiers

A method for realizing a sine-wave voltage-controlled oscillator (VCO) with a linear frequency to control voltage characteristics over three decades of frequencies, or more, in one sweep is discussed. The method employed is the conversion of a simple integrated square-wave VCO into a sine-wave VCO by separating the first-harmonic component and providing frequency shifting to achieve the desired output range. The sources of distortion of the output waveform are shown to be higher-order components of the square-wave used and higher-order components produced in the mixer. Possible improvements of the circuit are suggested, including the use of higher-order filters to reduce distortion and the use of a square-wave VCO operating at higher frequencies to provide operation at higher frequencies or over wider sweep ranges     

In-situ observation of faceted growth of benzophenone single crystals

Melt growth of benzophenone was in-situ observed under various cooling rate and temperature gradient. The melt growth experiments were performed for various cooling rate of melt and various temperature gradients. The movement of growth interface with time was measured for various growth faces such as (001), (101) and (011) and the growth rates of the respective faces were calculated. It was found that the growth rate of all the faces increased with cooling rate of the melt. Steady state growth was observed in the experiments with low temperature gradient while, the steep gradient leads to unstable growth of crystal. The observed growth rate variation was explained using the attachment energy model.     

Physical properties of fcc lanthanum under pressure

We report here a theoretical calculation of band strucure and superconductivity in the fcc phase of lanthanum under pressure. The effect of pressure on the band structure is obtained by means of the linear muffintin orbital method. McMillan's formula is used to calculate the superconducting transition temperature (T _c). It is found that the value ofT _c increases continuously up to 17.8 GPa and then begins to decrease. The change in the slope ofT _c is attributed to the appearance of a new piece of Fermi surface. The calculated values ofT _c are compared with the available experimental data.     

Phase transition in L-alaninium oxalate by photoacoustics

Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at 378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is not very sharp. This is discussed in detail with reference to the other known data for the organic crystals.     

Effect of thickness variation on stress analysis of piping elbows under internal pressure

Finite elements and computer codes are being used extensively for the calculation of deflections, terminal reactions and stresses in piping and pressure vessels. In these practices, pipelines are usually idealised by straight or curved beams. In contrast to this, the theory for pipe bend is based on differential equations of shell theory and by using the flexibility factor concept, it is possible to introduce the effect of bends into a pipe system. It can be said that inaccuracies in bend flexibility factors and stress intensification factors can lead to erroneous results when the straight lengths to which they are attached to are short. Thin walled piping elbow's wall thickness are likely to vary as a result of manufacturing processes. With the increasing use of thin-wall pipe at high stresses the effect of the internal pressure becomes significant. In the present paper stresses in a piping elbow due to internal pressure are studied in the presence of thickness variation.A finite element scheme with a doubly curved shell element which can account for variation in thickness has been utilized in the present paper. The effect of wall thickness variation in a 90° bend taking into account the end constraint due to tangent pipe to which they are attached to on the stress distribution has been studied for varying pipe factors.In order to study how the stress intensification factor will differ with different arc lengths, bends of various included angles having non-uniform wall thickness have been analyzed.The material of the piping system is assumed to behave elastically.Numerical results show that the non-uniform thickness of the bend wall does not affect maximum stress factor even in the case of bends with pipe factors of the order 0.05. For 90° bends as pipe factor increases from 0.05 the maximum stress factor increases and then decreases as pipe factor approaches 0.15. For other included angle bends the stress factor varies linearly with a maximum value at low pipe factor. The maximum stress factor is found to vary linearly with bend angle for all pipe factors and thinning factor of the pipe wall.     

Language issues in the implementation of a kernel

In this paper we present some issues encountered in the implementation of a kernel for a multiprocessor system using a high level language called CCNPASCAL. We present the nature of the problem concerning each issue, the solutions we adopted and possible better alternatives which we could not adopt for various reasons.     

Error estimates for conforming finite element solutions

A method for determining realistic error estimates for conforming finite element solutions is presented. The method requires solution of the problem by at least two, and preferably three mesh schemes that yield monotonic solution covergence. This in turn will automatically yield one solution bound, upper or lower. The paper describes a simple and practical scheme for obtaining the other bound by utilizing the solutions from the multiple mesh schemes. These bounds bracket the exact solution within relatively narrow limits and provide the basis of the error estimate. The solution quantities considered are the system energy quantities; and for eigenvalue problems these correspond to the eigenvalues themselves. As in convergence proofs, it is expected that the displacement and stress quantities will follow the behavior of the energy quantities. The proposed bounding method is applicable to eigenvalue and static problems devoid of stress singularities, and considers only the discretization error of conforming finite element models. The validity of the proposed bounding method has not been proved mathematically; however, extensive numerical applications of the method indicate its workability in every case tested. Results of some applications are included in this article.