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The photoluminescence and optical properties of MgxZn1-xTe alloys have been studied in the composition range 0xZn1-xTe alloys without altering the magnitude or the homogeneity of the magnesium concentration. Evidence is obtained for an increased quantum efficiency after lithium doping.

Transparent conducting zinc oxide (unintentionally doped) films were prepared by spray pyrolysis using air as the carrier gas. The optical and electrical properties of the films are presented and discussed as a function of the substrate temperature. The optical properties were studied in the ultraviolet (u.v.) visible and near infrared (i.r.) regions. The transmittance data were used to determine the optical constants, the refractive index, n, the extinction coefficient, k, and the absorption coefficient, a. The reflectivity of the films was calculated and found to be very small in the wavelengths investigated, showing a tendency to increase in the i.r. range in order to act as a host reflector.

An investigation was made of the plasma reflection of light and the results were used to find the effective mass of highly degenerate copper selenide,p>1020 cm-3, as a function of carrier concentrationp. The study of the temperature dependence of effective mass, electrical conductivity, thermoelectric power and Hall mobility carried out in the present work gives an idea of the nature of the valence bands in these materials.

To determine the seroprevalence of maternal and neonatal toxoplasmosis and cytomegalovirus (CMV) antibodies and hepatitis-B (HB) antigenaemia in a rural Egyptian area, a prospective serological study was done on a randomly selected sample of pregnant women (n = 150) and their newborn infants (n = 150). Sera were collected from the mothers during the first antenatal visit, and at the time of delivery and cord blood specimens (paired samples) taken from their infants to be tested for toxoplasma-IgG and IgM antibodies, CMV-IgG and IgM antibodies surface antigen (HBsAg) and HBe antigen (HBeAg). Maternal infection was indicated in cases where specific IgM antibody was present or where an initial maternal specimen gave negative result for IgG antibody, but the second blood specimen gave positive result. Specific IgM antibody in a cord blood specimen indicated fetal infection. Out of the 150 pregnant women, 64 (43 percent) were toxoplasma immune at their first antenatal visit and their newborns were toxoplasma IgG positive. Toxoplasma specific IgM antibody was detected in only three mothers at the time of deliver. The rate of maternal infection in susceptible pregnancies was 4 percent and the maternal-fetal transmission rate was estimated to be 33 percent, as only one newborn infant had toxoplasma-IgM antibody at birth. This denoted a prevalence of congenital toxoplasma infection = < 1.0 percent to non-immune mothers. There were no clinical features of congenital infection in the infant with toxoplasma-IgM antibody, but he will require long-term follow-up. All the mothers infected during pregnancy had known risk factors for toxoplasma infection. One-hundred-and-forty-three (96 percent) of the pregnant women were CMV-IgG seropositive at their first antenatal visit. At the time of delivery 143 (96 percent) of the mothers and their newborn infants were CMV-IgG seropositive. None of the mothers or their infants was CMV-IgM seropositive. HBsAg was detected in 8 per cent of pregnant mothers (n = 12) and in two (17 percent) of their newborn infants. None of the mothers was HBeAg positive. In conclusion, the prevalence of toxoplasma infection during pregnancy and its transplacental transmission rate in a rural Egyptian area are high compared to other countries. A toxoplasmosis antenatal screening and public education programmes for pregnant mothers is justifiable in rural Egypt. However, it appears that an antenatal screening programme for CMV is, at present, not warranted.

We studied the relationship of serum immunoglobulin-E (Ig-E) and interleukin-4 (IL-4) concentrations, eosinophil counts, and frequency of respiratory illness with passive smoking in 70 randomly selected children of smoking parents. Fifty randomly selected age-matched children of non-smoking parents served as controls. Children of smoking parents had higher frequency of respiratory illnesses per year (P < 0.01), significantly higher total leucocytic and eosinophil counts, higher percentage of eosinophils (P < 0.01), and higher serum IgE and IL-4 concentrations (P < 0.05) compared to the control group. Serum IgE level was correlated positively with the average number of smoked cigarettes/day, number of siblings, and total leucocytic count. Interleukin-4 concentrations were significantly correlated with the number of smoked cigarettes and IgE levels. Although IgE levels were higher in children of smoking parents (587 +/- 359 IU/ml) compared to controls (189 +/- 21 IU/ml), they did not differ significantly between children with and those without frequent respiratory illness (605 +/- 365 and 557 +/- 354 IU/ml, respectively). Interleukin-4 concentrations were significantly higher in children of smoking parents with frequent respiratory illness (1.8 +/- 0.5 pg/ml) v. those without frequent respiratory illness (1.3 +/- 0.45 pg/ml). Multiple logistic regression analysis revealed that the overall positivity of the risk factors predisposing to respiratory diseases in the study children was 79 percent, and the highest odds ratio was that for IL-4 (OR = 5.15). In conclusion, there is a significant increase in IL-4 and Ig-E concentrations, high eosinophil count and frequent respiratory symptoms in children of smoking parents. It remains that the current state of knowledge on health risks associated with passive smoking warrants that strong preventive action be promoted.

The importance of islet cell antibodies (ICA) as a predictor of insulin dependent diabetes mellitus (IDDM) has been emphasized by several investigators since 1974. The ICA was also detected in patients with various immune-mediated diseases such as auto-immune thyroiditis. Schistosomiasis is a wide-spread helminthic disease which affects more than 200 million patients all over the world. Immunological abnormalities and pancreatic affection are features of the disease. We studied the prevalence of ICA in 40 children with schistosomiasis (20 males and 20 females), 14 children with IDDM, and 30 of the non-diabetic siblings of patients with IDDM, and evaluated the oral glucose tolerance and early release of insulin after an i.v. load of glucose in children with schistosomiasis, diabetics' siblings, and 10 normal age-matched controls. The age of onset of IDDM and duration of the disease were 6.5 +/- 2.3 and 4.1 +/- 1.2, respectively, and the age of onset and duration of schistosomiasis were 8.3 +/- 2.7 and 2.5 +/- 1.5 years, respectively. Sex, consanguinity, history of previous virus diseases (mumps, measles and rubella), and sex maturity rating did not differ among the three study groups; however, children with schistosomiasis were significantly older. The prevalence of ICA was 50 per cent in children with IDDM, 13 per cent in the diabetics' siblings, and 25 per cent of children with schistosomiasis. Glucose tolerance was normal in children with schistosomiasis and diabetics' siblings. Early release of insulin after i.v. glucose load was significantly lower in children with schistosomiasis compared to the other two groups. In conclusion, the high prevalence of ICA and the decreased early release of insulin in response to an i.v. glucose load in children with schistosomiasis suggest that auto-immune aggression against the islet cells contributes in the pathogenesis of pancreatic disease in these patients, and might increase the risk for developing glucose intolerance and diabetes.

The influence of substrate temperature on the structural, optical and electrical properties of ZnO films prepared by the spray pyrolysis method using aqueous solution of zinc acetate has been investigated. The films are polycrystalline and X-ray diffraction measurements show a strong preferred orientation along the [002] plane which is strongly dependent on the substrate temperature. Optical absorption spectra, show high transparency of the film (90–95% transmission) in the visible range, with a sharp absorption edge around 375 nm wavelength of light which closely corresponds to the intrinsic band gap of ZnO (3.3 eV). ZnO films with the lowest resistivity, which is due to the increased mobility resulting from the improvement of the crystallinity of the films, can be prepared at a substrate temperature of 490 °C.

The room temperature photoelectric response of undoped and lithium-doped Zn1-xMgxTe (0 ? x ? 0.50) alloys has been measured in the wavelength range 0.50 ? ? ? 3.0 µm. The response curve for undoped samples is characterized by a single peak in the band edge region. The peak shifts with composition in accordance with the expected shift in the energy band gap. Lithium-doped samples show an additional peak centred at 1.04 eV for all compositions. This peak is attributed to photo-generated holes in the split-off band created as the result of electronic transitions to shallow acceptor impurities.