Optical and electrical characterization of CdS thin films

Thin CdS films have been grown by chemical bath (CdCl₂, thiourea, ammonia) deposition (CBD) on SnO₂ (TO)-coated glass substrate for use as window materials in CdS/CdTe solar cells. High-resolution transmission electron microscopy revealed grains with an average size of 10 nm. The structure was predominantly hexagonal with a high density of stacking faults. The film crystallinity improved with annealing in air. Annealing in a CdCl₂ flux increased the grain size considerably and reduced the density of stacking faults. The optical transmission of the as-deposited films indicated a band gap energy of 2.41 eV. Annealing in air reduced the band gap by 0.1 eV. Annealing in CdCl₂ led to a sharper optical absorption edge that remained at 2.41 eV. Similar band gap values were obtained by photocurrent spectroscopy and electroabsorption spectroscopy (EEA) using an electrolyte contact. EEA spectra were broad for the as-deposited and air-annealed samples, but narrower for the CdCl₂-annealed films, reflecting the reduction in stacking fault density. Donor densities of ca. 10¹⁷ cm ^–3 were derived from the film/electrolyte junction capacitance.     

Transport of chemical and microbial compounds from known wastewater discharges: potential for use as indicators of human fecal contamination

The quality of drinking and recreational water is currently (2005) determined using indicator bacteria. However, the culture tests used to analyze forthese bacteria require a long time to complete and do not discriminate between human and animal fecal material sources. One complementary approach is to use chemicals found in human wastewater, which would have the advantages of (1) potentially shorter analysis times than the bacterial culture tests and (2) being selected for human-source specificity. At 10 locations, water samples were collected upstream and at two successive points downstream from a wastewaster treatment plant (WWTP); a treated effluent sample was also collected at each WWTP. This sampling plan was used to determine the persistence of a chemically diverse suite of emerging contaminants in streams. Samples were also collected at two reference locations assumed to have minimal human impacts. Of the 110 chemical analytes investigated in this project, 78 were detected at least once. The number of compounds in a given sample ranged from 3 at a reference location to 50 in a WWTP effluent sample. The total analyte load at each location varied from 0.018 microg/L at the reference location to 97.7 microg/L in a separate WWTP effluent sample. Although most of the compound concentrations were in the range of 0.01-1.0 microg/L, in some samples, individual concentrations were in the range of 5-38 microg/L. The concentrations of the majority of the chemicals present in the samples generally followed the expected trend: they were either nonexistent or at trace levels in the upstream samples, had their maximum concentrations in the WWTP effluent samples, and then declined in the two downstream samples. This research suggests that selected chemicals are useful as tracers of human wastewater discharge.     

Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: a national reconnaissance

To provide the first nationwide reconnaissance of the occurrence of pharmaceuticals, hormones, and other organic wastewater contaminants (OWCs) in water resources, the U.S. Geological Survey used five newly developed analytical methods to measure concentrations of 95 OWCs in water samples from a network of 139 streams across 30 states during 1999 and 2000. The selection of sampling sites was biased toward streams susceptible to contamination (i.e. downstream of intense urbanization and livestock production). OWCs were prevalent during this study, being found in 80% of the streams sampled. The compounds detected represent a wide range of residential, industrial, and agricultural origins and uses with 82 of the 95 OWCs being found during this study. The most frequently detected compounds were coprostanol (fecal steroid), cholesterol (plant and animal steroid), N,N-diethyltoluamide (insect repellant), caffeine (stimulant), triclosan (antimicrobial disinfectant), tri(2-chloroethyl)phosphate (fire retardant), and 4-nonylphenol (nonionic detergent metabolite). Measured concentrations for this study were generally low and rarely exceeded drinking-water guidelines, drinking-water health advisories, or aquatic-life criteria. Many compounds, however, do not have such guidelines established. The detection of multiple OWCs was common for this study, with a median of seven and as many as 38 OWCs being found in a given water sample. Little is known about the potential interactive effects (such as synergistic or antagonistic toxicity) that may occur from complex mixtures of OWCs in the environment. In addition, results of this study demonstrate the importance of obtaining data on metabolites to fully understand not only the fate and transport of OWCs in the hydrologic system but also their ultimate overall effect on human health and the environment.     

Afro-American preferences for counselor characteristics.

Examined 128 Black college students' (aged 17–52 yrs) preferences for salient counselor characteristics. Ss were asked to express their preference for counselors similar or dissimilar to them across 8 counselor characteristics (ethnicity, sex, religion, educational background, socioeconomic background, attitudes and values, personality, and age) identified from previous research. A total of 120 paired comparisons were generated to compare preferences for the 16 similar and dissimilar counselor characteristics. Results reveal that Ss expressed preferences for counselors who, in comparison to themselves, were more educated, had similar attitudes and values, were older, and had similar personalities; these characteristics were more important to the Ss than the counselor's race and ethnicity. Additional analysis of within-group preference profiles revealed no consistent difference by commitment to Afro-American culture, sex, or previous counseling experience. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A profile of recently employed academicians in APA-approved and nonapproved counseling psychology programs.

Surveyed 70 26–42 yr old recipients of junior-level academic appointments in American Psychological Association (APA)-approved and nonapproved counseling psychology programs between September 1978 and September 1983 regarding demographic information, professional productivity, and personal contact networks. Results indicate that the successful applicant for an academic position was in his/her 30's, had a degree from an APA-approved program, and had completed a predoctoral internship. This candidate also had teaching experience and had articles published. Personal contacts were a salient factor in securing appointments in the approved programs. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Case study of attempts to enact self service tobacco display ordinances: a tale of three communities

OBJECTIVE: To examine self service tobacco displays (SSTDs) and youth retail tobacco access by comparing longitudinal illegal tobacco sales rates in three communities in Santa Barbara County, California, that considered or implemented ordinances banning SSTDs. A confirmatory survey was also conducted to substantiate the longitudinal data. DESIGN: A longitudinal case study design was utilised. Five undercover tobacco buys were conducted between 1994 and 1997 (n = 332). In addition, one confirmatory survey was conducted in a geographically separated area, which had no ordinances banning SSTDs (n = 57). RESULTS: Decreases in youth buy rates were reported in all three communities. Most notably, the first city to enact a SSTD ban, Carpinteria, achieved a 0% sales rate, which was maintained throughout the study period. In contrast, Santa Barbara and Goleta experienced considerable drops in their illegal sales rates, but neither community obtained results as dramatic as those found in Carpinteria. The confirmatory survey showed that 32.1% of stores with SSTDs sold cigarettes to minors; this compares to a sales rate of 3.4% in stores without SSTDs (chi(2) (1) = 8.11, p = 0.004). CONCLUSIONS: Efforts to enact self service bans are likely to meet with retail and tobacco industry opposition, as was the case in this study's three communities. The process of community debate, resultant publicity surrounding the issue, and enactment of SSTD ordinances may serve to not only increase merchant awareness of youth tobacco laws and their penalties but also may contribute to reduced youth cigarette sales rates. Implications and limitations of the findings are discussed.     

Paraoxonase (PON1) gene in mice: sequencing, chromosomal localization and developmental expression

PURPOSE: To retrospectively examine the optic disc photographs of a glaucoma population for optic disc haemorrhages, vascular occlusions and vascular abnormalities. METHODS: The optic disc photographs of 906 eyes of glaucoma and suspect glaucoma patients were examined. Optic disc photographs were taken annually, where possible, with the follow-up period varying between 1 and 14 years duration (mean, 2.89). Glaucoma patients are regularly reviewed every 4-6 months and glaucoma suspects every 1-2 years, depending on the ophthalmologist. Low-tension glaucoma patients were reviewed more frequently (mean, every 2.6 months). The results of the findings were compared to a control group of 39 subjects with a mean follow-up period of 7 years, using Fisher's exact test. RESULTS: It was found that during the period under review, 7.4% (n = 67) of eyes had optic disc haemorrhages. The highest frequency of optic disc haemorrhages (37.5%) was found in the low tension glaucoma group (P = 0.0001) followed by 11% of primary open-angle glaucoma eyes (P = 0.03). In the normal group there were three eyes with optic disc haemorrhages and one with a disc collateral, which constitutes 5.1% vascular changes in this sub-group. Of the study eyes 2.8% had central retinal vein occlusions, 1.3% branch vein occlusion, 1.2% disc vessel abnormalities (loops) and 1.1% disc collaterals. Discrete nerve fibre layer haemorrhages and microaneurysms were found in 0.8% and 1.8% of eyes, respectively. CONCLUSIONS: A total of 16.8% of the eyes observed in this study had either disc haemorrhages or vascular changes. The underlying trend of vascular and haemorrhagic changes in glaucoma are demonstrated in this sample, which is in general agreement with previous studies. The high percentage of optic disc haemorrhages in low tension glaucoma is highlighted. The presence of microaneurysms and nerve fibre layer haemorrhages is interesting but of unknown significance.