Effect of dysprosium active ions on spectral properties of KGW single crystals

Dysprosium (Dy) doped potassium gadolinium tungstate single crystals were grown by top seeded solution growth using K₂WO₄ as solvent. Two different concentrations of laser active ions were doped in the crystal. Crystals grown with lower growth rate using K₂WO₄ as solvent yielded better quality than that grown by K₂W₂O₇ as solvent. Growth conditions, like cooling rate and the rotation rate were optimized. Absorption studies confirm dominant absorption peaks in the visible as well as in near infrared regions. Photoluminescence reveals a strong yellow emission for the doped samples and the emission intensity of 3% Dy doped sample is 1.4 times higher than that of 1% Dy concentration in KGW. Raman spectra indicate the characteristic vibrational modes corresponding to the tungstate anion. The intensity of peaks in Raman spectra are increased with increase in concentration of Dy, in addition to a slight shift in Raman frequency.     

On the Estimation of True Hall–Petch Constants and Their Role on the Superposition Law Exponent in Al Alloys

Hall–Petch (HP) relation and the superposition of different strengthening mechanisms in different aluminum alloys with grain sizes in the range of 50 nm–70 µm were analyzed. HP parameters as high as σ₀ ≈ 200 MPa and k_HP ≈ 0.14 MPa m^1/2 were observed when the HP relation was fitted directly using the experimentally measured yield strength values. In contrast, considering only the grain size strengthening (by subtracting other strengthening contributions), HP constants of σ₀ ≈ 10 MPa and k_HP ≈ 0.06 MPa m^1/2 were obtained over wide range of grain sizes for the case of a linear superposition of the various strengthening mechanisms present. This is in excellent accord with the values obtained for pure Al justifying the chosen superposition exponent of n equal unity for the different alloys investigated.     

Biocompatibility studies of electrospun nanofibrous membrane of PLLA‐PVA blend

Electrospinning, self‐assembly, and phase separation are some of the techniques available for the synthesis of nanofibers. Of these techniques, electrospinning is a simple and versatile method for generating ultrafine fibers from a wide variety of polymers and polymer blends. Poly L ‐lactide (PLLA) and Poly (vinyl alcohol) (PVA) are biodegradable and biocompatible polymers which are mainly used for biomedical applications. Nanofibrous membranes with 1:9 ratio of PLLA to PVA (8 to 10 wt % and 10 wt %) were fabricated by electrospinning. The percentage porosity and contact angle of PVA in the PLLA‐PVA nanofibrous mat increased from 80 to 83% and from 39 ± 3° to 55 ± 3°, respectively. The water uptake percentage of PVA nanofibers decreased from 190 to 125% on the addition of PLLA to PVA in the PLLA‐PVA nanofibrous mat. The nanofiber morphology, structure and crystallinity were studied by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray diffraction (XRD), respectively. The thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimetery (DSC). The biocompatibility studies of PLLA‐PVA blend were performed using fibroblast cells (NIH 3T3) by MTT assay method. The release of Curcumin (0.5, 1.0, and 1.5 wt %) from PLLA‐PVA blend was found to be ～ 78, 80, and 80%, respectively, in 4 days. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Impact of genotype,seasons and manufacturing process on the activities of peptidase and lipoxygenase in tea

Tea flush shoots comprising three leaves and a bud were harvested from five different cultivars planted in a single area of UPASI Tea Research Farm and analysed for lipoxygenase (LOX) and peptidase activities. Among the cultivars, UPASI-3 recorded high peptidase activity, while UPASI-9 registered significantly higher lipoxygenase activity. This study suggested the influence of genotype on these enzymes. Green leaves sampled during mid-April to May (Premonsoon) exhibited higher peptidase activities, while LOX activity was predominant during monsoon period (June to August). Peptidase activity was higher in actively growing tea tissues (bud) and decreased with shoot maturity, whereas LOX activity significantly increased with the maturity of shoot from bud to third leaf and rapid decline in the internodes. During manufacturing process, the activity of both the enzymes varied widely and maximum peptidase activity was observed in withered leaves and cut dhool had maximum LOX activity. The flavour analysis was carried out in green leaf, withered leaf, cut dhool, fermented dhool and black tea which indicated that the value of flavour index was higher in final black tea and lowest in green leaf. This provides significant information that most of the aroma compounds are formed during processing (after harvesting only).     

Materials and methods of construction to resist the effects of cyclones

Failures of thousands of dwellings and that of a large number of engineered and non-engineered buildings and other industrial structures, caused by cyclones every year are of serious concern to professional engineers, scientists and researchers. The quality of common building materials used in the coastal regions of India such as stone and brick masonry, timber, steel and reinforced cement concerte, tiles, AC and other roofing sheets and also the effective methods of construction adopted, significantly affect the strength of structures in resisting severe cyclones. This paper discusses the common deficiencies on the properties of the materials used for walls and roofing of housing and other industrial structures, in resisting cyclonic wind forces and the ineffective construction practices leading to poor strength of overall structure. The paper also suggests some of the simple techniques to improve the cyclonic resistance of the structures.     

Effect of ethanol treatment on the proteins of Madhuca (Madhuca butyraceae) seed flour

Madhuca butyraceae flour was subjected to a two stage ethanol treatment to remove the toxic saponins and the effect of such treatment on the proteins was determined. Ethanol treatment caused minor changes in the amino acide composition and also in the gel filtration and gel electrophoretic patterns. The limiting amino acids in the ethanol treated flour are lysine and sulphur containing amino acids as compared to the provisional amino acid scoring pattern of FAO/WHO.     

Tracking Drug‐Induced Epithelial–Mesenchymal Transition in Breast Cancer by a Microfluidic Surface‐Enhanced Raman Spectroscopy Immunoassay

Epithelial–mesenchymal transition (EMT) is a primary mechanism for cancer metastasis. Detecting the activation of EMT can potentially convey signs of metastasis to guide treatment management and improve patient survival. One of the classic signatures of EMT is characterized by dynamic changes in cellular expression levels of E‐cadherin and N‐cadherin, whose soluble active fragments have recently been reported to be biomarkers for cancer diagnosis and prognosis. Herein, a microfluidic immunoassay (termed “SERS immunoassay”) based on sensitive and simultaneous detection of soluble E‐cadherin (sE‐cadherin) and soluble N‐cadherin (sN‐cadherin) for EMT monitoring in patients' plasma is presented. The SERS immunoassay integrates in situ nanomixing and surface‐enhanced Raman scattering readout to enable accurate detection of sE‐cadherin and sN‐cadherin from as low as 10 cells mL^?1. This assay enables tracking of a concurrent decrease in sE‐cadherin and increase in sN‐cadherin in breast cancer cells undergoing drug‐induced mesenchymal transformation. The clinical potential of the SERS immunoassay is further demonstrated by successful detection of sE‐cadherin and sN‐cadherin in metastatic stage IV breast cancer patient plasma samples. The SERS immunoassay can potentially sense the activation of EMT to provide early indications of cancer invasions or metastasis.     

Investigating the Effect of WC on the Hardness and Wear Behaviour of Surface Modified AA 6063

The objective of this work is to reinforce Tungsten Carbide (WC) onto the surface of AA 6063 aluminium alloy using Gas Tungsten Arc (GTA) as heat source and investigate the hardness and wear properties. Based on number of trials, optimum GTA heat source parameters are finalized with reference to the proper fusion of base metal. It is found that the hardness is reduced after the application of heat. After the reinforcement of WC, the hardness returns back to the base metal value. In order to further to improve the properties, the reinforced alloy is heat Treated. The Microhardness of the reinforced and aged AA 6063 is increased by 50% with respect to base metal. The wear resistance of the reinforced surface is improved by 52% with respect to base metal. Characterization techniques like SEM, EDX and XRD are done and the presence of WC is confirmed.