Preliminary assessment of the stability of thin- and polymer thick-film resistors embedded into printed wiring boards

Embedding passive components into multilayer printed wiring boards (PWBs) meet electronic device requirements concerning the necessity of saving the surface board area for active elements, reducing board’s size, improving device functionality and safety as well as overall product cost reduction. Since embedded components cannot be replaced after the board is completed, a long term stability and reliability are the important concerns for manufactures.This paper presents the results of examinations of embedded thin-film NiP resistors and polymer thick-film resistors during their continuous operation and the influence of temperature on the resistance values after the simulation of a lead-free soldering process and after the temperature cycling test (?40 ?C/+85 ?C).     

Biodegradable microfabricated plug-filters for glaucoma drainage devices

We report on the development of a batch fabricated biodegradable truncated-cone-shaped plug filter to overcome the postoperative hypotony in nonvalved glaucoma drainage devices. Plug filters are composed of biodegradable polymers that disappear once wound healing and bleb formation has progressed past the stage where hypotony from overfiltration may cause complications in the human eye. The biodegradable nature of device eliminates the risks associated with permanent valves that may become blocked or influence the aqueous fluid flow rate in the long term. The plug-filter geometry simplifies its integration with commercial shunts. Aqueous humor outflow regulation is achieved by controlling the diameter of a laser-drilled through-hole. The batch compatible fabrication involves a modified SU-8 molding to achieve truncated-cone-shaped pillars, polydimethylsiloxane micromolding, and hot embossing of biodegradable polymers. The developed plug filter is 500?μm long with base and apex plane diameters of 500 and 300?μm, respectively, and incorporates a laser-drilled through-hole with 44-μm effective diameter in the center.     

Effect of protein concentration, pH, lactose content and pasteurization on thermal gelation of acid caprine whey protein concentrates

The influence of pH (4.5-6.5), sodium chloride content (125-375 mM), calcium chloride content (10-30 mM), protein concentration (70-90 g/l) and lactose content on the gel hardness of goat whey protein concentrate (GWPC) in relation to the origin of the acid whey (raw or pasteurized milk) was studied using a factorial design. Gels were obtained after heat treatment (90 degrees C, 30 min). Gel hardness was measured using texture analyser. Only protein concentration and pH were found to have a statistically significant effect on the gel hardness. An increase in the protein concentration resulted in an increase in the gel hardness. GWPC containing 800g/kg protein formed gels with a hardness maximum at the pHi, whereas GWPC containing 300 g/kg protein did not form true gels. Whey from pasteurized milk formed softer gels than whey from raw milk. A high lactose content (approximately 360 g/kg) also reduced the gelation performance of GWPC.     

Rice field geochemistry and hydrology: an explanation for why groundwater irrigated fields in Bangladesh are net sinks of arsenic from groundwater

Irrigation of rice fields in Bangladesh with arsenic-contaminated groundwater transfers tens of cubic kilometers of water and thousands of tons of arsenic from aquifers to rice fields each year. Here we combine observations of infiltration patterns with measurements of porewater chemical composition from our field site in Munshiganj Bangladesh to characterize the mobility of arsenic in soils beneath rice fields. We find that very little arsenic delivered by irrigation returns to the aquifer, and that recharging water mobilizes little, if any, arsenic from rice field subsoils. Arsenic from irrigation water is deposited on surface soils and sequestered along flow paths that pass through bunds, the raised soil boundaries around fields. Additionally, timing of flow into bunds limits the transport of biologically available organic carbon from rice fields into the subsurface where it could stimulate reduction processes that mobilize arsenic from soils and sediments. Together, these results explain why groundwater irrigated rice fields act as net sinks of arsenic from groundwater.     

Evaluation of the safety assurance level for Salmonella spp. throughout the food production chain in Switzerland

In Switzerland. the safeguarding of food is the responsibility of industry, organizations, and governmental authorities. The dispersion of the tasks and the diversity of implemented safety measures among involved stakeholders do not allow a general overview of the national safety assurance level provided. A comprehensive evaluation of the level of safety assurance provided for foodborne pathogens such as Salmonella spp. is therefore lacking, and the prevalence of Salmonella spp. at various points in the food production chain is not known. The objectives of this study were to (i) collect data on safety measures implemented throughout the food production chain in Switzerland regarding Salmonella spp.; (ii) evaluate the safety assurance level for Salmonella spp. at each step of the production chain for chicken meat, pork, beef, and milk and dairy products (bovine origin); and (iii) gather data on the prevalence of the pathogen at each step. Data on implemented safety assurance measures for Salmonella spp. were gathered from the various stakeholders in the food production chain. The data were analyzed by a semiquantitative method that considered the quality and relevance of the implemented safety measures for Salmonella spp. The safety assurance level for Salmonella spp. was evaluated from "no safety assurance" to "very good safety assurance." Available results of testing for Salmonella spp. from 1998 to 2000 were used for calculating the prevalence of the pathogen throughout the food production chain. The results showed a varying safety assurance level for Salmonella spp. throughout the food production chain. Strengths (e.g., feed production for chickens) and weaknesses (e.g., pork production) were observed. These results serve as a basis for a rational optimization of the system.     

Apparent chemical composition of nine commercial or semi-commercial whey protein concentrates, isolates and fractions

Summary Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in β-lactoglobulin, four whey protein isolates and a fraction enriched in α-lactalbumin were analyzed for protein composition, including %β-lactoglobulin, α-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native β-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true β-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimated true β-lactoglobulin weight % of 70.9 ± 1.1, 62.0 ± 3.4 and 39.5 ± 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al ., 1999).     

Large scale isolation of gliadin fractions

The ω,- γ-, and α-gliadin groups were isolated by chromatography of 10 g of crude gliadin on Sulfopropyl Sephadex C50, followed by chromatographies of the SPS-C50 fractions on Sephadex G100. The alcohol-soluble glutenins separated from the SPS-C50 fractions containing the γ- and β-gliadins had lower contents of Asx, Ala and Tyr but higher contents of Thr, Ser and Met than the gliadins. On the basis of weights of the isolated fractions, the proportions of ω-, γ-, β- and α-gladin groups in Cappelle wheat were estimated to be about 15, 30, 30 and 25% of the total gliadin, respectively. This method of isolation of the four gliadin groups is suitable for all wheat varieties, especially for the isolation of α-gliadin.     

New types of synthetic infusion solutions. III. Elimination and retention of poly-[N-(2-hydroxypropyl)methacrylamide] in a test organism

The elimination and retention of a new, fully synthetic plasma prosthesis of Czechoslovak origin under the working name of Duxon (poly[N-(2-hydroxypropyl)methacrylamide]) was investigated in experiments on rabbits by using a 14C-labeled polymer. Results published earlier on elimination have been confirmed and extended. Retention was examined after repeated application. The effect of molecular weight prevailed both in elimination and in retention. Polymers of lower molecular weights, which possess a good therapeutical effect, are not permanently deposited in the organism.