Model reduction and process control of thermomechanical behaviour of non-linear material deformation

This paper describes a design procedure for metal forming processes by using the controllable subspace of the full system. The velocity profile of the moving die is designed using the reduced order system. The metal forming processes are simulated using non-linear finite element methods based on the rigid viscoplastic flow formulation. The balanced model reduction technique is applied to reduce the full state space model to a reduced order model that retains the controllable subspace of the thermomechanical system. The linear quadratic regulator theory with output tracking is used as an off-line design tool to design the die velocity schedule. The process design is carried out to maintain the strain rate of the critical portion of the billet at a desired value. The procedure for designing the process parameters is demonstrated using two case studies.     

Ionic liquid assisted one step green synthesis of Au–Ag bimetallic nanoparticles

Au–Ag bimetallic nanoparticles have been fabricated by one-step simple electrochemical deposition method using ionic liquid as green electrolyte (1-butyl-3-methylimidazolium tetrafluoro borate). Fabricated Au–Ag bimetallic nanoparticles have been characterized using cyclic voltammetry (CV), FE-SEM, UV–vis spectroscopy, and X-ray diffraction (XRD) studies. The electrodeposited Au–Ag bimetallic nanoparticles were found in the size range of 16–30 nm, respectively. This type of Au–Ag bimetallic nanoparticles could be directly applied for the optoelectronic and biosensing applications.     

Synthesis and characterization of poly(3‐octylthiophene)/single wall carbon nanotube composites for photovoltaic applications

In situ polymerization of P3OT with SWCNT is carried out in the presence of a FeCl₃ oxidant in a chloroform medium. The characterization of the composites is performed with FTIR, Raman, ¹H‐NMR, UV–Vis, PL spectroscopy, XRD, SEM, TEM, and conductivity measurements. The change (if any) in CC symmetric and antisymmetric stretching frequencies in FTIR, the shift in G band frequencies in Raman, any alterations in λ_max of UV–Vis and PL spectroscopic measurements are monitored with SWCNT loading in the polymer matrix. ¹H‐NMR confirms the wrapping of the polymer on to the SWCNT indicating lack of mobility. The work function values and the optical band gap values also support this view. The in situ polymerization procedure of the donor polymer molecules and the acceptor carbon nanotubes has resulted in enhanced dispersibility and stability of the composites in organic solvents. However, the principal focus of the study is to understand the interaction between the polymer and the SWCNTs, as the interface plays an important role in its application in the photovoltaic cells. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of black tea on histological and immunohistochemical changes in pancreatic tissues of normal and streptozotocin‐induced diabetic mice (Mus musculus)

The aim of the present study is to evaluate the effect of hot water extract of black tea in regenerating β cells in streptozotocin‐induced diabetic mice. Light microscopic examination of pancreatic sections of streptozotocin‐induced diabetic mice showed the acinar cells to be small, shrunken, and with deteriorated β cells. The dose of streptozotocin not only altered the function of β cells but also damaged the acinar region. The changes in acinar cells were coarsening of endoplasmic reticulation suggesting alteration in their secretory function. The control pancreatic tissue showed well‐defined granulated islets and dark β cells when stained with chrome hematoxylin and phloxine. Interestingly, pancreatic sections of diabetic mice fed with black‐tea extract showed regeneration of β cells and acinar region appeared normal with increased numbers of β cells. To understand the probable mechanism of action of black‐tea extract, we analyzed inducible nitric oxide synthase (iNOS) expression by immunohistochemistry and the results showed an increased iNOS levels in streptozotocin‐induced diabetic pancreas, and such high iNOS levels were inhibited in black‐tea extract treated mice. According to histological results obtained, it can be concluded that the black‐tea extract helps in regeneration of damaged pancreas and protects pancreatic β cells by its antioxidant action against nitrosative stress in streptozotocin‐induced diabetes. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

Effect of thermal boundary layer on radiative heat transfer from combustion plasma

The effect of thermal boundary layer on radiative heat transfer considering nongray nonisothermal plasma has been calculated for potassium seeded watergas combustion plasma. The effect of combustion species concentration and seed concentration on radiative flux under the equilibrium flow and frozen flow condition has been studied. It has been estimated that reduction in radiative flux due to cold boundary layer may be upto 25%.     

Preparation and Characterization of Hydroxyapatite-Coated Selenium Nanoparticles and their Interaction with Osteosarcoma（SaOS-2） Cells

Nanotechnology has taken a firm step to revolutionize the field of orthopedic implants. Current research on bone implants focuses to develop implants with multifaceted functions viz., osteoinduction, chemoprevention, antimicrobial action etc., especially for cancerous bone resection. The objective of the present study was to synthesize a novel composite for bone implants, possessing the above properties. Selenium was selected owing to its chemopreventive and chemotherapeutic properties. Hydroxyapatite was selected owing to its bioactivity and similarity in composition to bone mineral properties. Selenium nanoparticles were prepared by chemical reduction method and coated with hydroxyapatite.Hydroxyapatite-coated selenium nanoparticle（HASnp） was characterized physico-chemically using fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscope, and energy-dispersive X-ray spectroscopy.HASnp was analysed in vitro using SaOS-2 cell line. Enhanced cell proliferation and alkaline phosphatase activity were observed in HASnp-treated cells. The results indicate that HASnp is highly suitable for the use in orthopedic applications.     

Site-directed mutagenesis of the arginine-glycine-aspartic acid in vitronectin abolishes cell adhesion

Vitronectin (VN), a major cell adhesion protein, is found in plasma and in the extracellular matrix. At least three distinct cell surface receptors for vitronectin belonging to the integrin superfamily have been identified in normal and neoplastic cells. Many cell adhesion ligands, including vitronectin, contain an Arg-Gly-Asp (RGD) sequence mediating, in part, the ligand-receptor interaction. These ligands bind different integrins with varying specificity and affinity. The mechanism of receptor specificity remains controversial. To determine the role of the RGD sequence in receptor specificity, we amplified the cDNA for human vitronectin from a liver cDNA library and generated two separate mutants by utilizing site-directed mutagenesis resulting in aspartic acid (Asp47) to glutamic acid (Glu47) substitution and glycine (Gly46) to alanine (Ala46) substitution. The mammalian expression vector, pZEM229R, was used to transfect baby hamster kidney cells which secreted recombinant proteins into the supernatant. All recombinant proteins were isolated by heparin-agarose chromatography and tested for interaction with three known vitronectin receptors, namely, alpha IIIb beta 3 on thrombin-activated platelets, alpha v beta 3 on human umbilical vein endothelial cells and alpha v beta 5 on Panc-1 cells. Recombinant wild-type vitronectin behaved in a fashion similar to plasma-derived vitronectin. Both the RGE-VN and RAD-VN recombinant mutant proteins showed complete loss of cell adhesion activity, regardless of the receptor. These results confirm the essential and central role of the RGD sequence in vitronectin for cell adhesion. This expression system allows further structure/function analysis of vitronectin.