Measurement of Minority-Carrier Lifetime in Silicon Solar Cells by the Photoconductive Decay Method

One of the critical parameters for the overall efficiency of solar cells is the lifetime of minority carriers. This manuscript describes the measurement of minority - carrier lifetime of silicon solar cells, at room temperature, by photoconductive decay method. The Holobeam, Model 655 Double-Pulsed Holographic system, is used as the light source. This consists of a Q-switched, pulsed ruby laser oscillator with two ruby laser amplifiers. Silicon samples with projected lifetimes of less than O.25μ secs to about 8μ secs are used for the investigation, and the results obtained using this technique, compare favourably with the results furnished by the manufacturers

Dielectric Constants of Irradiated and Carbonated Polymers

Using the LC resonance circuit, changes in dielectric constants of irradiated and carbonated polymers as a function of carbon concentration are investigated. Both low and high density polymers are used. Results predict a quadratic increase in the dielectric constant of specimen as the percentage concentration of carbon is increased. This may be due to the formation of some polar groups which not only get polarized due to relative displacement of electrons and protons, but also have an inherent significant dipole lengths. Results also show that irradiation cases increase in the dielectric constant of both pure and carbonated polymers and that for a given composition, the dielectric constant increases with frequency. Irradiation effect is more pronounced for high density polymers than for low density polymers, and tends to disappear as carbon concentration increases

Construction and Calibration of a Local Pyranometer and its Use in the Measurement of Intensity of Solar Radiation

Using locally available materials, we have successfully constructed a pyranometer. This pyranometer has been calibrated against a standard Eppley pyranometer at the University of Nigeria, Nsukka and then used in measurement of intensity of solar radiation in Enugu which lies on latitude 6.200N-- and longitude 7. 30oE. The investigation was carried out between October and December 1984. Our investigations show that the maximum mean instantaneous insolation for the months of October November and December in Enugu were 565.6 Wm-2 , 600.6 Wm-2 and 580.4 Wm -2 respectively. The maximum instantaneous insolation for the period usually occured between 11.30 a.m. and 1.00 p.m. Our results also reveal that the sudden appearance of harmattan haze drastically reduced the mean hourly insolation. These results compare favourably with similar investigations using other techniques

Effects of Vitamin C Treatment on Serum Protein, Albumin, Beta-Globulin Profiles and Body Weight of Trypanosoma Brucei-Infected Rattus Noregicus

The effect of vitamin C supplements on serum protein profile and body weight of Trypanosoma brucei-infected rats was investigated. The rats were inoculated with trypanosomes intraperitoneally and samples were collected on fourth, eight, twelfth and sixteenth days of post infection (pi). Sixty (60) parasite free-albino rats were used, which were divided into four groups. Group A (control) was left uninfected with trypanosomes, group B and C were infected with Trypanosomes and treated with 40mls and 60mls of ascorbic acid (Vitamin C), respectively. Trypanosoma brucei infection caused significant (p<0.01) decreases in serum total proteins, albumin, beta globulin and body weight levels in untreated rats. Consumption of Vitamin C, however, prevented these diseaseinduced anomalies in the treated infected rats. Analyses of the sera using Bradford method and cellulose acetate electrophoresis showed that Vitamin C infected the state of serum protein, albumin and gamma globulin in the trypanosome-infected treated rats. It was concluded that consumption of the Vitamin C ameliorated the pathological changes in serum protein and body weight of T. brucei – infected rats.Keywords: Trypanosoma brucei, Rattus norvegicus, Ascorbic acid, Body weight, Serum protei

Convergence and stability theorems for the Picard-Mann hybrid iterative scheme for a general class of contractive-like operators

In this paper we use the general class of contractive-like operators introduced by Bosede and Rhoades (J. Adv. Math. Stud. 3(2):1-3, 2010) to prove strong convergence and stability results for Picard-Mann hybrid iterative schemes considered in a real normed linear space. We establish the strong convergence and stability of the Picard iterative scheme as a corollary. Our results generalize and improve a multitude of results in the literature, including the recent results of Chidume (Fixed Point Theory Appl. 2014:233, 2014)

Linkage to HIV care, postpartum depression, and HIV-related stigma in newly diagnosed pregnant women living with HIV in Kenya: a longitudinal observational study

BACKGROUND: While studies have suggested that depression and HIV-related stigma may impede access to care, a growing body of literature also suggests that access to HIV care itself may help to decrease internalized HIV-related stigma and symptoms of depression in the general population of persons living with HIV. However, this has not been investigated in postpartum women living with HIV. Furthermore, linkage to care itself may have additional impacts on postpartum depression beyond the effects of antiretroviral therapy. We examined associations between linkage to HIV care, postpartum depression, and internalized stigma in a population with a high risk of depression: newly diagnosed HIV-positive pregnant women. METHODS: In this prospective observational study, data were obtained from 135 HIV-positive women from eight antenatal clinics in the rural Nyanza Province of Kenya at their first antenatal visit (prior to testing HIV-positive for the first time) and subsequently at 6 weeks after giving birth. RESULTS: At 6 weeks postpartum, women who had not linked to HIV care after testing positive at their first antenatal visit had higher levels of depression and internalized stigma, compared to women who had linked to care. Internalized stigma mediated the effect of linkage to care on depression. Furthermore, participants who had both linked to HIV care and initiated antiretroviral therapy reported the lowest levels of depressive symptoms. CONCLUSIONS: These results provide further support for current efforts to ensure that women who are newly diagnosed with HIV during pregnancy become linked to HIV care as early as possible, with important benefits for both physical and mental health

Bioremediation of PCP by Trichoderma and Cunninghamella Strains Isolated from Sawdust

Four fungal isolates, SD12, SD14, SD19 and SD20 isolated from the aged sawdust grew on agar plates supplemented with PCP up to a concentration of 100 mg L-1. At high PCP concentration, isolate SD12 showed the highest radial growth rate of 10 mm day-1, followed by SD14 and SD19 both with 4.5 mm day-1 and SD20 with 4.2 mm day-1. Ultrastructural study on the effect of PCP on the PCP tolerant fungi using scanning electron microscope showed that high concentration of PCP caused the collapse of both fungal hyphae and spores. Among the four PCP tolerant fungi examined, isolate SD12 showed the least structural damage at high PCP concentration of 100 mg L-1. This fungal isolate was further characterized and identified as Cunninghamella sp. UMAS SD12. Preliminary PCP biodegradation trial performed in liquid minimal medium supplemented with 20 mg L-1 of PCP using Cunninghamella sp. UMAS SD12 showed that the degradation up to 51.7% of PCP in 15 days under static growth condition