Transport phenomena in laser surface alloying

A three dimensional, transient model is developed for studying heat transfer, fluid flow and mass transfer for the case of a single-pass laser surface alloying process. The numerical study is performed in a co-ordinate system fixed to the laser which moves with a constant scanning speed. The coupled momentum, energy and species conservation equations are solved using a finite volume technique. Phase change processes are modelled using a fixed-grid enthalpy-porosity technique, which is capable of predicting the continuously evolving solid-liquid interface. The three-dimensional model is able to predict the species concentration distribution inside the molten pool during alloying, as well as in the entire cross section of the solidified alloy. Corresponding experimental results show a good qualitative agreement with the numerical predictions with regard to pool shape and final composition distribution.     

An algorithm for generating color scales for both categorical and ordinal coding

Previous research has shown multihue scales to be well‐suited to code categorical features and shown lightness scales to be well‐suited to code ordinal quantities. We introduce an algorithm, Motley, that produces color scales varying in both hue and lightness, intended to be effective for both categorical and ordinal coding, allowing users to determine both absolute and relative quantities efficiently and accurately. The algorithm first determines the lightnesses of scale colors to maximize perceived lightness differences and establish the lightness ordering, generating separate search spaces for each scale position. It then selects hues by heuristic search to maximize the discriminability of the scale. It produces scales that are ordered with respect to lightness but unordered with respect to hue and thus more discriminable than typical multihue lightness scales. In an experimental evaluation on human subjects, Motley's scales enabled accurate judgments of relative quantity, with response times superior to unordered multihue scales and comparable to ordered lightness scales, and enabled accuracy and speed of judgments of absolute quantity superior to lightness scales and comparable to multihue scales. Published 2009 Wiley Periodicals, Inc., Col Res Appl, 2010.     

The Enriched Feature Enhancement Technique for Satellite Image Based on Transforms Using PCNN

The features of the satellite images can be improved by fusing or combining two images with complementary property. By fusing these two images the spatial property of the resultant image is improved. Satellite images are one of the agents that give the features of the earth’s surface. Processing these satellite images will provide more geographical information hidden in the images. This research paper have an detailed insight study of two types of the satellite images one is Panchromatic (PAN) and other Multispectral (MS). The PAN image with high spatial resolution and MS image with spectral resolution are fused to get better resultant output. For fusion process Nonsubsampled Contour let Transform is used to decompose the images into low and high frequency values. Pulse Coupled Neural Network is used to motivate the low frequency pixel and Morphological filter is applied to the edge detected image for finding the features in the images. This is an real time transformations which will give better results in SAR image processing, video processing, stereo based reconstruction of depth and width of the features present in the image.

     

Oxidation Kinetics of an Amorphous Silicon Carbonitride Ceramic

The oxidation kinetics of amorphous silicon carbonitride (SiCN) was measured at 1350°C in ambient air. Two types of specimens were studied: one in the form of thin disks, the other as a powder. Both specimens contained open nanoscale porosity. The disk specimens exhibited weight gain that saturated exponentially with time, analogous to the oxidation behavior of reaction-bonded Si₃N₄. The saturation value of the weight gain increased linearly with specimen volume, suggesting the nanoscale pore surfaces oxidized uniformly throughout the specimen. This interpretation was confirmed by high-resolution electron microscopy and secondary ion mass spectroscopy. Experiments with the powders (having a particle size much larger than the scale of the nanopores) were also consistent with measurements of the disks. However, the powder specimens, having a high surface-to-volume ratio, continued to show measurable weight gain due to oxidation of the exterior surface. The wide range of values for the surface-to-volume ratio, which included all specimens, permitted a separation of the rate of oxidation of the free surface and the oxidation of the internal surfaces of the nanopores. Surface oxidation data were used to obtain the rate constant for parabolic growth of the oxidation scale. The values for the rate constant obtained for SiCN lay at the lower end of the spectrum of oxidation rates reported in the literature for several Si₃N₄ and SiC materials. Convergence in the behavior of SiCN and CVD-SiC is ascribed to the purity of both materials. Conversely, it is proposed that the high rates of oxidation of sintered polycrystalline silicon carbides and nitrides, as well as the high degree of variability of these rates, might be related to the impurities introduced by the sintering aids.     

Mesoporous Pt–Ni catalyst and their electro catalytic activity towards methanol oxidation

Mesoporous Pt/Ni architecture has been prepared by template assisted electrochemical deposition of Pt–Ni over anodized aluminum oxide template followed by controlled de-alloying with nitric acid. Surface characteristics of the ordered bimetallic mesoporous Pt/Ni structure were systematically characterized through XRD, SEM, AFM and XPS analyses. It is designated by XPS analysis that presence of Ni significantly modifies surface characteristics and electronic states of Pt accompanied with a downshift in the d-band character of Pt. Mesoporous morphology is highly beneficial to offer readily accessible Pt catalytic sites for methanol oxidation reaction. The prepared bimetallic Pt/Ni was used as electro catalyst for DMFC. Comparison of electrocatalytic activity of bimetallic mesoporous Pt/Ni with bimetallic smooth Pt/Ni was interrogated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy analyses. Distinctly enhanced electrocatalytic activity with improved CO tolerance associated with bimetallic mesoporous Pt/Ni electrode towards methanol oxidation stems from a synergy existing between mesoporous structure with bi-metallic composition.     

Structure-function studies of an IGF-I analogue that can be chemically cleaved to a two-chain mini-IGF-I

The structure and biological activities of two disulphide isomersof a C-region deletion mutant of insulin-like growth factor-I(IGF-I) which has an Asn–Gly link engineered at the junctionof the A- and B-regions were studied before and after chemicalcleavage. Circular dichroism (CD) spectra and binding affinityto IGF binding protein 3 (IGFBP3) indicated that the treatmentwith hydroxylamine did not disrupt the overall tertiary foldof the hormones. Cleavage restored some binding affinity forthe IGF-I receptor in both isomers and weakly restored the abilityto stimulate incorporation of tritiated thymidine into DNA inNIH 3T3 fibroblasts transfected with the human IGF-I receptor.Cleavage also restored metabolic capacity, as measured by theability of the isomers to promote lipogenesis in isolated ratadipocytes through the insulin receptor. These results are consistentwith the theory that binding of IGF-I to the IGF-I receptorrequires a conformational change similar to that involved ininsulin binding the insulin receptor. The weak affinity forthe IGF-I receptor after cleavage is consistent with the beliefthat residues in the C-region interact with the IGF-I receptor.This structural difference between insulin and IGF-I gives eacha higher binding affinity for its own receptor.     

On the application of CAD technology for the synthesis of spatial revolute–revolute dyads

This work presents a method based on Computer Aided Design or CAD for facilitating the synthesis of Revolute–Revolute (R–R) dyads with adjustable moving pivots. The CAD-based method presented in this work ensures that all prescribed rigid-body parameters used to synthesize the R–R dyad satisfy particular kinematic requirements of an R–R dyad. Through the application of this CAD method, five of the six general R–R dyad constraint equations are satisfied and therefore not essential for the synthesis of the R–R dyad. By reducing the number of dyad design constraints from six to one, the user can synthesize R–R links with adjustable moving pivots for multi-phase motion and path generation applications. The example included demonstrates the use of the CAD method in the synthesis of an RRSS path generator with adjustable moving pivots.     

Validation of SV2A-Targeted PET Imaging for Noninvasive Assessment of Neuroendocrine Differentiation in Prostate Cancer

Neuroendocrine prostate cancer (NEPC) is an aggressive and lethal variant of prostate cancer (PCa), and it remains a diagnostic challenge. Herein we report our findings of using synaptic vesicle glycoprotein 2 isoform A (SV2A) as a promising marker for positron emission tomography (PET) imaging of neuroendocrine differentiation (NED). The bioinformatic analyses revealed an amplified SV2A gene expression in clinical samples of NEPC versus castration-resistant PCa with adenocarcinoma characteristics (CRPC-Adeno). Importantly, significantly upregulated SV2A protein levels were found in both NEPC cell lines and tumor tissues. PET imaging studies were carried out in NEPC xenograft models with ¹⁸F-SynVesT-1. Although ¹⁸F-SynVesT-1 is not a cancer imaging agent, it showed a significant uptake level in the SV2A⁺ tumor (NCI-H660: 0.70 ± 0.14 %ID/g at 50–60 min p.i.). The SV2A blockade resulted in a significant reduction of tumor uptake (0.25 ± 0.03 %ID/g, p = 0.025), indicating the desired SV2A imaging specificity. Moreover, the comparative PET imaging study showed that the DU145 tumors could be clearly visualized by ¹⁸F-SynVesT-1 but not ⁶⁸Ga-PSMA-11 nor ⁶⁸Ga-DOTATATE, further validating the role of SV2A-targeted imaging for noninvasive assessment of NED in PCa. In conclusion, we demonstrated that SV2A, highly expressed in NEPC, can serve as a promising target for noninvasive imaging evaluation of NED.     

Robust control of HIV infection by antiretroviral therapy: a super‐twisting sliding mode control approach

Acquired immune deficiency syndrome is an epidemic infectious disease which is caused by the human immunodeficiency virus (HIV) and that has proliferated across worldwide. It has been a matter of concern for the scientific community to develop an antiretroviral therapy, which will prompt a rapid decline in viral abundance. With this motivation, this study proposes the design of a robust super twisting sliding mode controller based on output information for an uncertain HIV infection model. The control objective is to decrease the concentration of infected CD4+ T cells to a specified level by drug administration using only the output information of the uncertain HIV infection model which is total CD4+ T cell concentration. The robust output‐feedback controller has been developed in combination with a robust exact differentiator, functioning as an observer. The reported analysis demonstrates that the approach proposed here is capable of ensuring robust performance under several operating conditions, measurement and modelling error, parametric uncertainties and external disturbances and the simulation results prove the proficiency of the controller proposed.Inspec keywords: control system synthesis, observers, robust control, drugs, medical control systems, diseases, uncertain systems, variable structure systems, patient treatment, feedback, cellular biophysics, microorganismsOther keywords: robust control, antiretroviral therapy, sliding mode control approach, acquired immune deficiency syndrome, epidemic infectious disease, human immunodeficiency virus, scientific community, robust super, mode controller, output information, uncertain HIV infection model, control objective, infected CD4, total CD4, T cell concentration, robust output‐feedback controller, robust exact differentiator, robust performance     

Pramila Rao · D. Sujatha · K. Rathina Raj · S. Vishwanatha · K. Narasimhamurthy · P. Saibaba · D. Narasimha Rao · S. Divakar

 Subchronic toxicity dietary studies were conducted in albino rats on the safety aspects of residual β-cyclodextrin in egg samples treated for cholesterol removal at concentrations of 250, 125 and 20 ppm for a period of 90 days. Daily food intake, body weight gain, relative organ weights, histopathology, haematology and serum enzyme activities were studied. The study however, did not reveal any toxicity at any of the levels tested. It can therefore be concluded from the present study that β-cyclodextrin-treated egg samples do not cause any toxicity. Received: 28 September 1999