Mutagenic and genotoxic activities of four pesticides: captan, foltaf, phosphamidon and furadan

The mutagenic and genotoxic potential of four pesticides viz. captan, foltaf, phosphamidon and furadan was evaluated by the Ames mutagenicity assay and their DNA damaging ability on radiation repair defective E. coli K-12 strains respectively. The mutagenic spectrum revealed captan to be most mutagenic in the absence of metabolic activation, while the presence of S9 mix led to an attenuated mutagenic response. Foltaf, phosphamidon and furadan were detected as relatively weaker mutagens. A significant decrease in the survival of SOS defective mutants, recA, lexA and pol- of E. coli was observed as compared to their wild-type counterparts in the presence of the pesticides. The role of SOS repair genes gains further support from the Salmonella strains triggering the error-prone SOS response.     

Outcome of hepatitis C patients with and without hepatocellular carcinoma undergoing liver transplant

OBJECTIVE: Hepatitis C virus (HCV) infection is associated with development of hepatocellular carcinoma (HCC). The aim of this study was to examine clinical characteristics and outcome of patients with HCV with or without HCC undergoing liver transplant. METHODS: We reviewed the charts of all 55 patients transplanted between November 1990 and December 1996 for HCV cirrhosis with HCC and compared them with a control group of HCV patients without HCC. Patients with a history of alcohol abuse or HBsAg positivity were excluded. There were 37 men and 18 women, with a mean age of 57.6 yr (range, 19-70 yr) in the HCC group. RESULTS: There was no significant difference between the HCC and nonHCC groups regarding Child's class or United Network for Organ Sharing (UNOS) status at the time of transplant. Twenty-six (45%) patients were diagnosed or suspected of having HCC before transplant. Twenty-five patients (45.5%) had a single focus of HCC. Fourteen percent (seven of 50) of the patients with HCC had been treated with interferon, whereas 12% (six of 52) of patients in the nonHCC group had received interferon. Duration of interferon therapy ranged from 1 to 9 months. All interferon treatment occurred within 5 yr of transplant. A history of intravenous drug use or transfusion was identified in 37 (67%) of HCC patients. Thirty-two patients (58%) without HCC had a parenteral exposure. There was no significant difference in patient or graft survival rates between the patients with and without HCC. CONCLUSION: Approximately one-half of HCC was not detected before liver transplant. There was no significant difference in the mode of transmission, clinical status at the time of transplant, or outcome between the HCV patients with and without HCC.     

Screening of prostate cancer in males with prostatism

Genetic analysis of the population structure of the western blacklegged tick, Ixodes pacificus Cooley & Kohls, was conducted using allozymes. This vector tick transmits the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, in the far-western United States. It ranges from British Columbia to Baja California and disjunct populations are present in Oregon, Nevada, Utah, and Arizona. Host-seeking adult ticks were collected from vegetation across the range of the species and were partially fed on rabbits prior to analysis. Twelve putative loci were resolved using starch gel electrophoresis. One locus, glucose-6-phosphate isomerase, formed an apparent north/south latitudinal cline and showed significant geographic structure. None of the remaining loci exhibited much genetic differentiation. Estimates of gene flow were high relative to other arthropods. Isolation-by-distance analysis suggests a recent and rapid range expansion. We conclude that the overall lack of differentiation is due high rates of gene flow.     

The organometallic vpe growth of GaSb and GaAsl−xSbx using trimethylantimony

The organometallic vapor phase epitaxial (OMVPE) growth of GaSb and GaAs_l−xSb_x (0 ≤ × ≤ 0.26, 0 .64 ≤ × ≤1) is discussed. Trimethylgallium and trimethylantimony are used as the Ga and Sb source, respectively. Most GaAs_1× Sb_x growths are done using arsine, but the use of an alternate arsenic source, trimethylarsenic, is also discussed. In contrast to most arsenic-containing alloys, both GaSb and Sb-rich GaAs_1−x Sbx are grown under Group III-rich conditions. The total input flux as well as the ratio of the input chemicals must be closely regulated. In particular, growth of GaAs_l−xSb_x requires careful control of the trimethylantimony-to-total Group V ratio, since arsenic preferentially incorporates into the crystal. This work was supported by DOE through the Division of Materials Science Branch of the Office of Basic Energy Sciences under Contract No. DE-AC03-79SF10610.     

Sky component grids for glazed vertical windows

Daylight contribution at a point due to sky visible through different areas of a window is a function of the sky luminance, the projected solid angle of these areas at the reference point on the working plane and the transmittance of glass. The transmittance of glass varies considerably with the angle of incidence, which depends upon the relative positions of different parts of a window opening with respect to the reference point. A sky component grid, representing the sky component values from different elemental areas of openings in a window wall, forms one of the simplest ready reckoners in daylighting design. This paper presents the methodology of generating sky component grid for any sky condition. The relevant data on mean altitude of grid elements, the mean angle of incidence for different grid elements, and differential sky factors are included for facilitating the computation of grid values. The sky component grid for Indian clear design sky based on exact equations of sky component for a horizontal plane, with a due allowance for transmittance of 3 mm thick clear glass, is provided for comparing the accuracy of the methodology based on differential sky factors. The values computed from the data and the methodology presented in this paper agree closely with the exact values. The deviation of computed values from exact values is less than ±10%.     

Syndrome and transition count are uncorrelated [logic circuittesting]

In the testing of logic circuits, two proposed data-compression methods use the number of ones (syndrome) and the number of sequence changes (transition count). An enumeration N(m, k , t) of the number of length-m binary sequences having syndrome value k and transition count t is developed. Examination of this result reveals that the parallel compression of these two methods has small overlap in error masking. An asymptotic expression for N(m, k, t) is developed     

Switching characteristics of an optically controlled GaAs-MESFET

The switching characteristics of an optically controlled Metal Semiconductor Field Effect Transistor (MESFET), popularly known as Optical Field Effect Transistor (OPFET), have been derived analytically. The limitations of the existing model have been overcome in the present model. Calculations are being carried out to examine the effect of illumination on the current-voltage characteristics, drain-to-source capacitance (C_dc), internal gate-to-source capacitance (C_gs), drain-to-source resistance (R_ds), the transconductance (g_m), the input RC time constant and the cutoff frequency (f_T) of a GaAs-MESFET. The variations of these parameters with gate length L_g and the doping concentration N_d have also been studied in dark and illuminated conditions. The results of numerical calculations show that there is an overall decrease in the input RC time constant of the device in the illuminated condition arising from the internal gate-to-source capacitance and the transconductance. The results obtained on the basis of the model show a close agreement with the reported experimental findings. The simple model presented here is fairly accurate and can be used as a basic tool for circuit simulation purposes     

An equilibrium model for predicting flue-gas composition of an incinerator

The composition of an incinerator flue gas depends characteristically on the operating parameters such as combustion temperature, fractional excess air value, and moisture content of the waste material. An a priori knowledge of the influence of these parameters on the flue-gas composition helps to carry out the combustion process efficiently by appropriately selecting their values. A simple chemical equilibrium model is proposed to predict the flue-gas composition from an incinerator at different operating temperatures, excess air values, and moisture contents of the combusting material. The predicitions are supposed to establish the upper limit of the chemical species concentrations in the flue gas and hence the model is considered as an appropriate one for selecting the pollution control equipment and in estimating the upper limit of environmental contamination. The model-based computations predict that at a given temperature and moisture content, the increase in excess air decreases the concentrations of carbon monoxide, carbon dioxide, water, and hydrogen in the flue gas while it increases that of oxygen. Similarly, the proportion of nitrogen dioxide, nitrogen, sulfur dioxide and sulfur trioxide decreases while that of nitric oxide increases. At a given excess air and moisture content, the increase in temperature decreases the concentrations of carbon monoxide and hydrogen and increases of carbon dioxide and water due to better combustion. Similarly, the increase in temperature also augments the concentrations of nitric oxide, nitrogen dioxide and sulfur dioxide while it decreases that of nitrogen and sulfur trioxide. Similar trends are observed at different levels of moisture content.     

Transverse vibration of a quarter of an elliptic plate with variable thickness

Rayleigh-Ritz method has been used to find the first three frequencies and mode shapes for free flexural vibration of a plate in the form of a quadrant of an ellipse with linear and quadratic thickness variations. The results for a quarter of a circular plate with uniform thickness have been obtained as a special case and comparison has been made with results already available. By taking various combinations of clamped, simply-supported and completely-free edges we get twenty-seven different cases. Tables are given for the first three frequencies for different values of parameters. Mode shapes have also been plotted in some cases. The convergence of results is indicated by working out approximations of various orders.