Design of multijunction GaPNAs/Si heterostructure solar cells by computer simulation

The designs of two- and three-junction solar cells based on GaPNAs/Si lattice-matched hetero-structures are calculated. It is shown that the efficiency of two-junction solar cells constituted by a junction based on a GaPNAs solid solution with a band gap E _g of 1.78 eV and a junction based on Si may reach a value of 30.3% under AM1.5 D, 100 mW/cm², and 35.4% under AM1.5D, 20 W/cm². The maximum values of the efficiency of the three-junction solar cell constituted by top and middle junctions based on GaPNAs with E _g of 2 and 1.5 eV, respectively, and a Si-based bottom junction are 39.2% under AM1.5 D, 100 mW/cm², and 44.5% under AM1.5D, 20 W/cm². It is shown that the thickness and minority carrier lifetime of the photoactive layers affect the efficiency of solar-light conversion by the heterostructures being developed.     

Evaluation of the quality of GaAs epitaxial layers and their interfaces from analysis of the exciton absorption spectra

Exciton optical spectra are sensitive to even slight changes in the properties of a solid. The spectra of exciton polaritons can be especially informative, although the spectroscopy of these quasiparticles imposes certain restrictions on the measurement temperature and the quality of the material. Exciton parameters such as the resonance frequency ω _T and damping coefficient Γ may vary under the influence of electric fields, defects present in the crystal, or changes in the chemical composition of the film. If the material characteristics vary along the thickness of the film (the z coordinate), so do the resonance frequency and damping coefficient. Here, the spectra of undoped GaAs layers epitaxially grown on GaAs substrates are investigated at T = 1.7 K. Analysis of the spectra at the exciton absorption edge makes it possible to estimate the “dead-layer” depth, the strength of electric fields, and the concentration of impurities.     

Modification of synthetic materials to reduce combustibility

The studies conducted demonstrated the effectiveness of using Phosdiol for reducing the combustibility of PE fibres and the small effect of PAN and PA fibre fire barriers. The oxygen index of flameproof fibrous polyester material was 27.5%, which allows assigning it to difficultly combustible polymers, and the strength of the fibre increases by 12–15%. __________ Translated from Khimicheskie Volokna, No. 1, pp. 35–38, January–February, 2006.     

光纤传输电视伴音的二次调制技术

本文简述光纤传输电视伴音的二次调制技术的基本原理,并对实现二次调制的实际电路进行了详细分析。     

Dynamic course of neurological syndromes in very young children with the history of intrauterine growth retardation

90 infants with intrauterine growth retardation (IGR) and 100 normal infants (control group) were followed up from 5 days till 3 years of life. In IGR infants there was a more frequent combination of several neurologic syndromes, an early manifestation of motor disorders (from the very moment of birth), a delay of neuro-psychic development (during the first year of life), a tendency to development of moderate hydrocephalus by the age of 6 months. Autonomic-visceral disorders in them were mostly characterized by the symptoms of abaissement, but not of irritation.     

Prevalence and demographic determinants of metronidazole resistance by Helicobacter pylori in a large cosmopolitan cohort of Australian dyspeptic patients

1. Heterozygous naked neck birds were raised under natural spring (average 21.2 degrees C) and summer temperatures (average 27.1 degrees C) to investigate the influence of dietary energy on broiler performance, carcase yield and nutrient composition of breast meat. 2. Birds were fed on a low energy diet of 12.12 MJ ME/kg, a medium energy diet of 12.96 MJ ME/kg and a high energy diet of 13.79 MJ ME/kg with 2 protein concentrations per energy treatment, 230 and 200 g/kg, from 0 to 3 and 3 to 7 weeks of age, respectively. 3. Summer rearing resulted in a decrease in body weight, body weight gain, carcase weight and carcase part yields of birds. 4. Increasing dietary energy from 12.12 to 13.79 MJ ME/kg increased body weight at 3 and 7 weeks, body weight gains from 0 to 3 and 3 to 7 weeks, carcase weights and relative abdominal fat weights of birds in a linear manner. There was no effect of dietary energy on the nutrient composition of breast meat. 5. It was concluded that there was no differences in dietary energy requirements of heterozygous naked neck birds when grown under natural optimum (21.2 degrees C) and summer temperatures (27.1 degrees C).     

Suc-Phe-Leu-Phe-SBzl--a new substrate for functional study of Escherichia coli ATP-dependent Lon-proteinase and its modified forms

A new efficient substrate, Suc-Phe-Leu-Phe-SBzl, was proposed for studying the function of the Escherichia coli ATP-dependent Lon protease and its modified forms. The kinetic parameters of hydrolysis of the substrate were determined. The esterase activity of protease Lon was found to be nucleotide-regulated.     

Randomised trial of heroin maintenance programme for addicts who fail in conventional drug treatments

OBJECTIVE: To evaluate an experimental heroin maintenance programme. Design: Randomised trial. SETTING: Outpatient clinic in Geneva, Switzerland. SUBJECTS: Heroin addicts recruited from the community who were socially marginalised and in poor health and had failed in at least two previous drug treatments. INTERVENTION: Patients in the experimental programme (n=27) received intravenous heroin and other health and psychosocial services. Control patients (n=24) received any other conventional drug treatment (usually methadone maintenance). Main outcome measures: Self reported drug use, health status (SF-36), and social functioning. RESULTS: 25 experimental patients completed 6 months in the programme, receiving a median of 480 mg of heroin daily. One experimental subject and 10 control subjects still used street heroin daily at follow up (difference 44%; 95% confidence interval 16% to 71%). Health status scores that improved significantly more in experimental subjects were mental health (0.58 SD; 0.07 to 1.10), role limitations due to emotional problems (0.95 SD; 0.11 to 1.79), and social functioning (0.65 SD; 0.03 to 1.26). Experimental subjects also significantly reduced their illegal income and drug expenses and committed fewer drug and property related offences. There were no benefits in terms of work, housing situation, somatic health status, and use of other drugs. Unexpectedly, only nine (38%) control subjects entered the heroin maintenance programme at follow up. CONCLUSIONS: A heroin maintenance programme is a feasible and clinically effective treatment for heroin users who fail in conventional drug treatment programmes. Even in this population, however, another attempt at methadone maintenance may be successful and help the patient to stop using injectable opioids.