The Effect of Surface Treatment on Nickel Leaching from Nitinol

Nitinol is widely used as a biomaterial for implantable medical devices but can be susceptible to nickel leaching. Our research was aimed at determining nickel leaching from surface treated Nitinol samples, treated as follows: mechanical polishing (untreated), oxidation, and nitriding+oxidation (5 different nitriding temperatures). Five specimens from each category were immersed in 40 mL PBS solution and incubated at 37°C over 91 days. Nickel concentration readings were taken at regular intervals. After 91 days, the average nickel concentration in the PBS solution was (a) 0.223 mg/L, SD 0.017, untreated, (b) 7.68 mg/L, SD 6.405, 1000°C nitriding+oxidation, and (c) 3.914 mg/L, SD 1.78, oxidation-only. The concentration readings had large standard deviations implying differences in surface characteristics after treatment. The increased nickel leaching from treated samples was thought to be due to atomic diffusion and exposure of the nickel-rich sublayers to PBS after oxide layer delamination. These sublayers formed after formation of thick (\u3e1 µm) TiO2 layers during oxidation

Scale Optimization of Milkguard Biosensor for Detecting E. coli in Human Breast Milk

Milkguard is an alginate-based biosensor developed to detect E. coli in human breast milk via the metabolism of X-gal (5-Bromo-4-Chloro-3-Indolyl β-D-Galactopyranoside) by β-galactosidase. In order to deconvolute metabolic reproducibility from scaling laws, the commercial enzyme β-galactosidase was used to mimic the biological function of the bacterial lac operon. Downscaling was explored as an optimization of the biosensor design based on numerical solutions to Fickian-based diffusion models. The characterization of large capsules (d ≅ 3 mm) and atomized microcapsules (d ≅ 300 ± 60 μm) yielded size-specific Michaelis-Menten constants. Small capsules (Km = 3.6 x 10-4 M; Vmax ’’ = 1.2 x 10-3) produced a significantly faster response time versus large capsules when loaded at a substrate concentration of 5 mg/mL (p = 7.7x 10-3 at = 0.01) and 2.5 mg/mL (p = 1.5 x 10-4 at \u3c 0.001). Comparisons of effectiveness factors between small (η = 0.58) and large (η = 0.43) capsules indicates a lesser degree of diffusion limitations in small capsules. Large bootstrapping errors produced by nonlinear regression of Michaelis-Menten models for the capsules suggests that additional mechanisms to diffusion are involved in producing sensor response. A new sensor mechanism combining Fickian diffusion and experimental results is proposed and modeled numerically

Effect of Ignatzshineria indica (Gammaproteobacteria: Xanthomonadales) on rate of decomposition in mice

Microbes have a major role from the onset of and throughout decomposition. Studies show that a decomposing body supports a necrobiome (Pechal et al., 2013), a term coined to mean a community of living things associated with decomposition of remains, specifically with reference to microorganisms. The objective of the current study is to show how Ignatzschineria indica, a fly associated, and selected bacteria associated with a decomposing human body affect decomposition under controlled (laboratory) conditions. The work presented here is a laboratory experiment carried out at Sam Houston State University, Huntsville, Texas. To assess the effect of Ignatzschineria indica bacteria on decomposition, 3 batches of 90 mice were subjected to 9 different bacterial treatments involving 4 bacteria; A [Ignatzschineria indica], B [Escherichia coli], C [Bacillus licheniformis], D [Salmonella enterica], and combinations of Ignatzchineria indica and other bacteria in the following manner BA, CA, DA, PC [positive control] and NC [negative control]. 270 mice were observed throughout their decomposition process. Results from this experiment showed that the initial bacteria composition in dead mice does not affect the rate of decomposition under laboratory controlled conditions of temperature and moisture, with the exclusion of vertebrate and invertebrate scavengers. Adding Ignatzchineria indica to dead mice specimens under laboratory controlled conditions does not significantly affect the rate of decomposition but instead affects the pathway of decomposition. This was evident from the different intensities of volatile organic compounds (VOCs) that were collected and assayed from the different samples. The same experiment shows that at any given time the ambient temperature is significantly different from the subjects’ temperatures during decomposition. Our findings lead us to conclude that the addition of Ignatzschineria indica bacteria to decomposing mice does not significantly alter the rate of decomposition. It does alter the chemical pathways of decomposition as evidenced by variant VOCs composition

Phase transitions in superionic PbSnF₄

PbSnF\sb4 is the highest performance fluoride ion conductor known to date. We have studied the phase transitions it undergoes under three different conditions: (i) versus the amount of hydrofluoric acid used for the preparation by the aqueous route, (ii) upon application of mechanical energy, and (iii) versus temperature. The addition of an aqueous solution of lead(II) nitrate to a fresh aqueous solution of SnF\sb2 results in the precipitation of $\alpha$-PbSnF\rm\sb4(aq\sb1), which is very highly strained in the ($\vec a,\vec b$) plane of the tetragonal unit-cell. If a very minor amount of hydrofluoric acid is used, the strain increases and o-PbSnF\sb4 is obtained. The $\alpha$-PbSnF\sb4\to o-\rm PbSnF\sb4 transition is mostly a bidimensional phase transition, which includes a highly disordered intermediate "transitional phase". Ball milling results in a phase transition, giving microcrystalline disordered $\mu\gamma$-PbSnF\sb4, a cubic $\beta$-PbF\sb2 like phase. Tests were performed to make sure the $\mu\gamma$-PbSnF\sb4 samples are indeed microcrystalline cubic PbSnF\sb4 and not a mixture of microcrystalline $\beta$-PbF\sb2 and amorphous SnF\sb2. Milling $\alpha$- and $\beta$-PbF\sb2 for comparison and testing showed that both $\beta\to\alpha$ and $\alpha\to\beta$ transitions take place upon milling. Stirring $\alpha$-PbF\sb2 in an aqueous solution of SnF\sb2 results in the formation of $\rm\alpha$-PbSnF\rm\sb4(aq\sb2) or \rm Pb\sb2SnF\sb6 depending on the conditions whereas no reaction occurs with $\beta$-PbF\sb2. When all the phases of PbSnF\sb4 are heated, phase changes take place versus temperature and time. Our findings provide key knowledge that will have to be taken into account in the fabrication of practical devices using PbSnF\sb4 for guaranteed reproducible results, long term stability and stable output of the device

Modifying the size of nanopores of alginate microcapsules

Alginate hydrogels provide desirable biocompatibility and material properties for various biomedical applications, but are limited by the polymer\u27s natural pore size. With the rise of nanotechnology, the desired crosslinked pore size range of 30 nm to 100 nm has not yet been achieved. This project aimed to develop a method to increase the pore size of alginate-based hydrogels in a reproducible manner without compromising their structural integrity. Experimental methods included altering alginate composition using carboxymethyl cellulose or gelatin and inducing conformational changes via Mach-1TM mechanical compression. Fluorescence microscopy was used to visualize the diffusion of FITC-dextran weight markers and fluorescent polystyrene nanoparticles into the microcapsules (d = 300 μm) and macrocapsules (d = 3 mm) for all experimental conditions. Based on pilot experiments, altered alginate composition did not significantly increase the pore size of alginate capsules for the modeled diffusivity range D = 1 x 10-14 m2/s to D = 1 x 10-15 m2/s. Mechanical compressions did not significantly affect the porosity or diffusivity of alginate macrocapsules (p \u3e 0.05) under all conditions for Young’s moduli ranging from E = 76 kPa to E = 200 kPa. Based on image analysis results, it could be hypothesized that molecular weight cutoff cutoff may be increased to 500 kDa following 10 successive compressions. Additional work to optimize fluorescent microscopy methods and pore size manipulation methods is required for expanded use of alginate capsules with emerging nanotechnologies

PENGARUH FEE BASED INCOME DAN INTELLECTUAL CAPITAL TERHADAP PROFITABILITAS PADA INDUSTRI PERBANKAN DI BURSA EFEK INDONESIA

This study aims to identify and analyze the effects of fee based income and intellectual capital(value added capital employed, value added human capital and structural capital value added) on profitability at banking industries in Indonesia Stock Exchange. This study employs 16 samples out of 33 banking industries which have been selected using purposive sampling method. Analysis method used in this study is multiple linier regression. The results shows that: (1) fee based income, value added capital employed, value added human capital, structural capital value added simultaneously perform significant effects on profitability at banking industries in Indonesia Stock Exchange, (2) fee based income performs positive but not significant effect on profitability at banking  industries  in  Indonesia  Stock  Exchange,  (3)  value  added  capital  employed  performs positive and significant effect on profitability at banking industries in Indonesia Stock Exchange, (4) value added human capital performs positive and significant effect on profitability at banking industries in Indonesia Stock Exchange, (5) structural capital value added performs negative and not significant effect on profitability at banking industries in Indonesia Stock Exchange

Evaluation of Bambara groundnut varieties for off-season production in Zimbabwe

Early planting of bambara groundnuts (Vigna subterranea L. Verdc) in the southern Africa enables farmers to fetch premium prices before the markets are flooded with produce from the main summer growing period.However, adaptation of the crop outside the main growing season has not been studied in Zimbabwe. Therefore, this study evaluated 20 varieties at four planting dates covering contrasting temperatures and daylength, at Harare Research Station, during 2000/2001. Planting date was the main plot factor replicated three times and cultivar the subplot. Standard agronomic practices were followed and adequate moisture supplied through supplementary irrigation. Both the planting dates and variety main effects were significant (

Analyzing Pili Nut Value Chains in Sorsogon Province, Philippines

The importance of the pili nut (Canarium ovatum Engl.) industry cannot be discounted due to its immense domestic potential in Sorsogon Province, Philippines, where 62% out of the total volume of canarium nut production in the Bicol Region is concentrated. This paper examined the pili nut value chain network in the study area. Supplemented by secondary data sources, primary data gathering was conducted involving interviews with 15 pili farmers, 30 processors, and 20 traders located in Sorsogon City and 5 other pili-growing towns in Sorsogon Province. Analytical tools such as descriptive and net margin analyses were used. Results showed that farmers, processors, processor-wholesaler-retailers, processor-retailers, wholesaler-retailers, and retailers comprised the value chain. Four pili pulp and shelled pili chains where processors were not participants were identified while 12 dried kernel chains were mapped out. Selling dried kernel pili during the lean season gives farmers the highest value at PhP147.94 per kilogram rather than selling raw or shelled pili where returns are only one-fifth of this value. Traders refrain from buying dried kernel pili from farmers since they prefer buying pili with pulp and shelled pili so they can do the processing themselves. Chain problems include the lack of technical, financial, and information support; scattered location of pili farms; and low levels of product innovation. Recommendations offered include forming a cooperative or consolidating group to assemble all harvests, justify the purchase of depulping and other processing equipment, hasten production and processing technology transfer, and increase competitiveness