Study of Nitrogen Implanted in Aluminum at Various Doses

Experimental and theoretical studies are carried out to understand transport of nitrogen in aluminum during implantation process. 60 keV and 120 keV N₂⁺ ion are implanted in pure Al substrates at doses ranging from l×l0¹⁷ to 9×l0¹⁷ N-atoms per cm². RBS and Glancing angle XRD studies are carried out. RBS studies show that the depth profiles are gaussian in nature at low doses and gradually become rectangular in shape as the dose increases. XRD analysis reveals that AlN is formed even at low doses. Theoretical simulations of depth profiles at low dose, include displacement mixing and radiation enhanced diffusion, which are modelled to be described by a diffusion like process. Effective diffusion coefficient in radiation environment is found to be equal to 8×l0^-16 cm².sec^-1. At high doses, when new N-atoms are added during implantation their transport gets linked with the already formed AlN. This leads to a rectangular shape of depth profiles observed at high doses.     

On the measurement of microwave absorption of bulk YBaCuO superconductors in X-band (8–12 GHz)

Microwave absorption at the surface of highT _c YBaCUO superconducting sample has been determined in X-band by measuring VSWR. Power reflectivity >98% has been observed in the frequency range of 8·2–10·5 GHz indicating very low absorption at the surface. At some of the frequencies, however, negligible microwave loss has been observed.     

One-group theory of a control rod with an elliptical cross section placed confocally in a multiplying system of similar cross section

One-group theory in the diffusion approximation has been developed to calculate the value of a control rod of elliptical cross section placed confocally in a multiplying assembly of similar cross section. The result is compared with that for a circular rod placed coaxially in a multiplying assembly of circular cross section.     

Influence of gain saturation, gain asymmetry, and pump/probedepletion on wavelength conversion efficiency of FWM in semiconductoroptical amplifiers

The effects of gain saturation, gain asymmetry, and pump/probe depletion on the conversion efficiency of four-wave mixing (FWM) in semiconductor optical amplifiers are studied analytically and numerically. The power dependence of FWM coupling coefficients and ultrafast relaxation-related gain mechanisms are included in the model. By studying the FWM efficiency in the transition from unsaturated to strongly saturated regions, it is seen that gain asymmetry results in deviation from small-signal models when the pump-probe detuning and pump powers are small. At high pump injection or gain conditions, it is also shown that the small-signal model breaks down even for relatively large detuning frequencies. Probe depletion is also seen to be critical under saturated conditions and an upper bound is derived for ranges of input pump power, pump-probe detuning, and gain for a given amplifier under which the small-signal model is valid     

Improvement in Corrosion Resistance of Biomaterial Alumina after 60 keV Nitrogen Ion Implantation

Surface modification of polycrystalline α-alumina is carried out using ion implantation. Samples were implanted at 60 keV N⁺ ions with different ion doses ranging from 1 × 10¹⁵ to 1 × 10¹⁷ ions/cm². Corrosion resistance is studied in a Ringer solution. The increase in corrosion resistance is due to the compound formation studied using Fourier transform infrared spectroscopy and glancing-angle X-ray diffraction techniques. Nanohardness is more at a lower ion dose and decreases at a higher ion dose. Microstrutural investigation shows that the decrease in corrosion resistance and nanohardness at a higher ion dose is due to the damage accumulation at the surface.     

An open label study to determine the effects of an oral proteolytic enzyme system on whey protein concentrate metabolism in healthy males

Background

Current research suggests that protein intake of 1.5 – 2.8 g/kg/day (3.5 times the current recommended daily allowance) is effective and safe for individuals trying to increase or maintain lean muscle mass. To achieve these levels of daily protein consumption, supplementing the diet with processed whey protein concentrate (WPC) in liquid form has become a popular choice for many people. Some products have a suggested serving size as high as 50 g of protein. However, due to possible inhibition of endogenous digestive enzymes from over-processing and rapid small intestine transit time, the average amount of liquid WPC that is absorbed may be only 15 g. The combined effect of these factors may contribute to incomplete digestion, thereby limiting the absorption rate of protein before it reaches the ceacum and is eliminated as waste. The purpose of this study was to determine if Aminogen^®, a patented blend of digestive proteases from Aspergillus niger and Aspergillus oryzae, would significantly increase the in-vivo absorption rate of processed WPC over control values. It also investigated if any increase would be sufficient to significantly alter nitrogen (N2) balance and C-reactive protein (CRP) levels over control values as further evidence of increased WPC absorption rate.

Methods

Two groups of healthy male subjects were assigned a specified balanced diet before and after each of two legs of the study. Subjects served as their own controls. In the first leg each control group (CG) was dosed with 50 g of WPC following an overnight fast. Nine days later each test group (TG) was dosed following an overnight fast with 50 g of WPC containing either 2.5 g (A2.5) or 5 g (A5) of Aminogen^®. Blood samples were collected during each leg at 0 hr, 0.5 hr, 1 hr, 2 hr, 3 hr, 3.5 hr and 4 hr for amino acid (AA) and CRP analyses. The following 18 AAs were quantified: alanine, arginine, aspartic acid, cysteine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine. Urine was collected for 24 hours from 0 hr for total N2 analysis. Results are expressed as means ± SEM. All significance and power testing on results was done at a level of alpha = 0.05. Area under the concentration time curve (AUC) was calculated using the trapezoidal rule. One-way analysis of variance (ANOVA-1) was done between CGs, between TGs and between time points. One-way repeated measures analysis of variance (ANOVA-1-RM) was done to compare CGs and TGs. Two-way analysis of variance (ANOVA-2) was performed on total serum amino acid (TSAA) levels, urine N2 levels and CRP levels between each CG and TG.

Results

After baseline subtraction the mean AUC was significantly (p ≤ 0.05) greater in each TG compared the corresponding CG. Comparison of the mean AUC between each TG and each CG was not significantly different. Total serum amino acid (TSAA) levels were significantly greater in each TG compared the corresponding CG. They were also significantly different between each TG but not between each CG. All individual serum amino acid (ISAA) levels in TG-A2.5 except glycine, histidine, methionine and serine were significantly higher than in CG-A2.5 at 4 hr. All ISAA levels in TG-A5 except methionine and serine were significantly higher than in CG-A5 at 4 hr. The N2 balance was significantly higher in each TG compared to the corresponding CG, but not significantly different between each CG and between each TG. Significant differences in CRP levels are reported between each TG compared to the corresponding CG, but not significantly different between each TG and between each CG.

Conclusion

A patented blend of digestive proteases (Aminogen^®) increased the absorption rate of processed WPC over controls, as measured by statistically significant increases in AUC, TSAA levels, ISAA levels and N2 balance. Significant decreases in CRP levels and fluxes in AA levels are also reported.

     

Rapid synthesis of silver nanoparticles by Pseudomonas stutzeri isolated from textile soil under optimised conditions and evaluation of their antimicrobial and cytotoxicity properties

Present study utilised textile soil isolated bacterium Pseudomonas stutzeri to synthesise extracellular silver nanoparticles (AgNPs) under optimised conditions. The synthesised AgNPs were characterised using ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Optimisation showed AgNPs synthesis within 8 h using 2mM Ag nitrate at pH9, temperature 80°C and maximum absorbance toward 400 nm. TEM analysis revealed spherical shape AgNPs and reduction in size upto 8 nm was observed under optimised conditions. FTIR spectra confirmed presence of proteins bound to AgNPs act as reducing agent. AgNPs showed strong antibacterial activity against multi‐drug resistant (MDR) Escherichia coli and Klebsiella pneumoniae as demonstrated by disc diffusion and colony forming unit assays. Zone of inhibition increased with increasing concentration of AgNPs with maximum of 19 mm against E. coli and 17 mm against K. pneumoniae at concentration of 2 μg/disc. Furthermore, AgNPs did not show any cytotoxic effects on human epithelial cells as demonstrated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay even at 2 μg/ml concentration of AgNPs. The results of the present study suggest that AgNPs can be synthesised rapidly under optimised conditions and show strong antimicrobial property against MDR pathogens without having toxicity effect on human epithelial cells.Inspec keywords: ultraviolet spectra, proteins, transmission electron microscopy, infrared spectra, Fourier transform spectra, visible spectra, microorganisms, toxicology, cellular biophysics, biomedical materials, antibacterial activity, nanomedicine, nanofabrication, nanoparticles, silverOther keywords: 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay, human epithelial cells, cytotoxic effects, K. pneumoniae, colony forming unit counting assays, disc diffusion, Klebsiella pneumoniae, Escherichia coli, multidrug resistant, stabilising agent, reducing agent, proteins, parametric optimisation, TEM, transmission electron microscopy, FTIR spectra, Fourier transform infrared spectroscopy, ultraviolet‐visible spectroscopy, bacterium, cytotoxicity properties, antimicrobial properties, textile soil, Pseudomonas stutzeri, silver nanoparticle synthesis