Both hypothyroidism and hyperthyroidism enhance low density lipoprotein oxidation

Hypothyroidism is frequently associated with hypercholesterolemia and an increased risk for atherosclerosis, whereas hyperthyroidism is known to precipitate angina or myocardial infarction in patients with underlying coronary heart disease. We have shown previously that L-T4 functions as an antioxidant in vitro and inhibits low density lipoprotein (LDL) oxidation in a dose-dependent fashion. The present study was designed to evaluate the changes in LDL oxidation in subjects with hypothyroidism and hyperthyroidism. Fasting blood samples for LDL oxidation analyses, lipoprotein determinations, and thyroid function tests were collected at baseline and after the patients were rendered euthyroid. The lag phase (mean +/- SEM hours) of the Cu+2-catalyzed LDL oxidation in the hypothyroid state and the subsequent euthyroid states were 4 +/- 0.0.65 and 14 +/- 0.68 h, respectively (P < 0.05). The lag phase during the hyperthyroid phase was 6 +/- 0.55 h, and that during the euthyroid phase was 12 +/- 0.66 h (P < 0.05). The total and LDL cholesterol levels were higher in hypothyroidism than in euthyroidism and were lower in hyperthyroidism than in the euthyroid state. We conclude that LDL has more susceptibility to oxidation in both the hypothyroid and hyperthyroid states. Thus, the enhanced LDL oxidation may play a role in the cardiac disease process in both hypothyroidism and hyperthyroidism.     

Formation of part families to design cells with alternative routing considerations

A heuristic algorithm for the formation of part families to design cells with consideration to alternative routing of parts is presented. Most of the existing algorithms in cellular manufacturing systems utilize fixed routings for parts. Consideration of alternative routings in the design of cells is important for improving operational aspects of cellular manufacturing systems. An example problem solved is included in the paper.     

Fixed-point error analysis of discrete Wigner-Ville distribution

The Wigner-Ville distribution (WVD) has been a powerful signal processing tool for time-frequency signal analysis. Consequently, many algorithms have been proposed in the literature for computing the WVD in real-time applications. However, Boashash (1987) has proposed and showed that the evaluation of the analytic signal using the time-domain approach, and involving the Hilbert transformer, is the most efficient algorithm for real-time applications. A fixed-point error analysis of this algorithm has been carried out. The theoretical noise-to-signal ratio (NSR) is derived and verified through simulation. The results indicate that for this algorithm, the NSR increases by 0.5 bit/stage, whereas for the other algorithms, it increases by 1 bit/stage     

Biodegradation of nitrate esters. II. Degradation of nitrocellulose by a fungus isolated from a double-base propellant

An organism found to be growing on moist double-base propellant, containing nitrocellulose (NC) and nitroglycerine aerobically degraded NC in submerged cultivation. This organism, which was subsequently identified as Penicillium corylophilum Dierckx, was able to degrade the NC (13.17%N) when it was present as the sole nitrogen source, in conjunction with either starch or xylan as a carbon source. It was found that 20% of the NC was utilized in a 3-day period. Also, NC degradation was studied utilizing Fusarium solani IFO 31093, a denitrifying fungus, in combination with P. corylophilum; however, no increased utilization was observed. Evidence for the degradation includes a decrease in the NC weight, an increase in the biomass weight, the presence of celluloytic and denitrifying enzymes, and other appropriate growth parameters. © 1995 John Wiley & Sons, Inc.     

Measurement of the current transient in Ta2O5 films

Current vs. time (I−t) measurements were performed on Ta₂O₅-based devices. Charge build-up at the Ta₂O₅/SiO₂ interface was used to explain the transient. The interfacial charge density was calculated from the I−t curve and the maximum was found to be 398 nC cm^-2 and 317 nC cm^-2 for Al/Ta₂O₅/Si and Al/Ta₂O₅/SiO₂/Si capacitors respectively. The value for MTOS was comparable with the value obtained by quasi-static measurements.     

Noise-margin limitations on gallium-arsenide VLSI

Two factors which limit the complexity of GaAs MESFET VLSI circuits are considered. Power dissipation sets an upper complexity limit for a given logic circuit implementation and thermal design. Uniformity of device characteristics and the circuit configuration determines the electrical functional yield. Projection of VLSI complexity based on these factors indicates that logic chips of 15000 gates are feasible with the most promising static circuits if a maximum power dissipation of 5 W per chip is assumed. While lower power per gate and therefore more gates per chip can be obtained by using a popular E/D FET circuit, yields are shown to be small when practical device parameter tolerances are applied. Further improvements in materials, devices, and circuits will be needed to extend circuit complexity to the range currently dominated by silicon     

Quasi-static and high frequency C-V measurements on Al/Ta2O5/SiO2/Si

Quasi-static and high frequency capacitance-voltage (C-V) measurements of Al/Ta₂O₅/SiO₂/Si (MTOS) capacitors are analysed. Space charge build-up at the Ta₂O₅-SiO₂ interface and the frequency response of these charges are explained. It is also found that the leakage current is not the sole contributor to the discrepancies observed in quasi-static measurements, as suggested in the literature. An estimate of the interface charge is also presented.     

Diffused junction p+−n solar cells in bulk GaAs—II: Device characterization and modelling

The photovoltaic characteristics of p⁺-n junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are presented in detail. Quantum efficiency measurements were analyzed and compared to computer simulations of the cell structure in order to determine material parameters such as diffusion length, surface recombination velocity and junction depth. From the results obtained it is projected that proper optimization of the cell parameters can increase the efficiency of the cells to close to 20%.     

Thermodynamics study of liquid Cu−Mg alloys by vapor pressure measurements

Metallurgical and Materials Transactions B -