Minority carrier lifetime in silicon photovoltaics : the effect of oxygen precipitation

Single-crystal Czochralski silicon used for photovoltaics is typically supersaturated with interstitial oxygen at temperatures just below the melting point. Oxide precipitates therefore can form during ingot cooling and cell processing, and nucleation sites are typically vacancy-rich regions. Oxygen precipitation gives rise to recombination centres, which can reduce cell efficiencies by as much as 4% (absolute). We have studied the recombination behaviour in p-type and n-type monocrystalline silicon with a range of doping levels intentionally processed to contain oxide precipitates with a range of densities, sizes and morphologies. We analyse injection-dependent minority carrier lifetime measurements to give a full parameterisation of the recombination activity in terms of Shockley–Read–Hall statistics. We intentionally contaminate specimens with iron, and show recombination activity arises from iron segregated to oxide precipitates and surrounding defects. We find that phosphorus diffusion gettering reduces the recombination activity of the precipitates to some extent. We also find that bulk iron is preferentially gettered to the phosphorus diffused layer rather than to oxide precipitates

Barley malt-based composition as a galactagogue — a randomized, controlled trial in preterm mothers

Objectives: Delayed or insufficient breast milk production, as well as low milk supply, is still a challenging problem toovercome, particularly in the case of preterm delivery. Herbal galactagogues might be a good way to increase milk supply,however, there is a lack of clinical studies confirming their efficacy and safety.The aim of this study was to verify the safety and effectiveness as a galactagogue of the unique galactagogue compositionbased on barley malt with β -glucan and lemon balm.Material and methods: The study included 117 mothers of preterm infants randomly divided into the GalactagogueGroup given galactagogue and the Placebo Group. A complete data set was obtained for 80 participants, divided equallybetween two groups.Volume of milk expressed by mothers during the first two weeks after delivery was the primary outcome and safetyof the product was the secondary outcome.Results: Volume of milk recorded on participants’ last visit in the Galactagogue Group was significantly higher than in thePlacebo Group (95 mL vs 62.5 mL, p = 0.049). The total expressed milk volume during the study was 4209 ± 335 mLin the Placebo Group vs 6036 ± 498 mL (p = 0.003) in the Galactagogue Group.Conclusions: Supplementation with unique Galactagogue composition was safe and increased milk output which allowedachieving target minimal volume of 500 mL per day in first week of lactation in preterm mothers

Compressibility of the high-pressure rocksalt phase of ZnO

We report the results of a combined experimental and theoretical investigation on the stability and the volume behavior under hydrostatic pressure of the rocksalt (B1) phase of ZnO. Synchrotron-radiation x-ray powder-diffraction data are obtained from 0 to 30 GPa. Static simulations of the ZnOB1 phase are performed using the ab initio perturbed ion method and the local and nonlocal approximations to the density-functional theory. After the pressure induced transition from the wurtzite phase, we have found that a large fraction of the B1 high-pressure phase is retained when pressure is released. The metastability of this ZnO polymorph is confirmed through the theoretical evaluation of the Hessian eigenvalues of a nine-parameter potential energy surface. This allows us to treat the experimental and theoretical pressure-volume data on an equal basis. In both cases, we have obtained values of the bulk modulus in the range of 160–194 GPa. For its zero-pressure first derivative, the experimental and theoretical data yield a value of 4.4±1.0. Overall, our results show that the ZnOB1 phase is slightly more compressible than previously reported

Quality of life in childhood epilepsy with lateralized epileptogenic foci

<p>Abstract</p> <p>Background</p> <p>Measuring quality of life (QOL) helps to delineate mechanisms underlying the interaction of disease and psychosocial factors. In adults, epileptic foci in the left temporal lobe led to lower QOL and higher depression and anxiety as compared to the right-sided foci. No study addressed the development of QOL disturbances depending on the lateralization of epileptogenic focus. The objective of our study was to examine QOL in children with lateralized epileptiform discharges.</p> <p>Methods</p> <p>Thirty-one parents of children with epilepsy filled the Health-Related Quality of Life in Childhood Epilepsy Questionnaire (QOLCE). Fifteen children had foci in the left hemisphere and sixteen in the right, as verified with Electroencephalography (EEG) examinations.</p> <p>Results</p> <p>We found a significant correlation between foci lateralization and reduced QOL (Spearman's rho = 0.361, p < 0.046). Children with right hemispheric foci exhibited lower overall QOL, particularly in five areas: anxiety, social-activities, stigma, general-health, and quality-of-life.</p> <p>Conclusions</p> <p>We demonstrated for the first time that in children left- and right-hemispheric foci were associated with discordant QOL scores. Unlike in adults, foci in the right hemisphere led to worse emotional and social functioning demonstrating that seizures impact the brain differentially during development.</p

Effects of mellitic acid (MA) and sodium fluoride (NaF) on the histological appearance of murine fetal tibiae cultured in vitro

The aim of this studv was to develop a standardized image analysis method for localization and quantitative measurement of calcified structures of murine fetal tibiae cultured in vitro as a completion and verification of previous biochemical studies. The calcified structures of bone stained by von Kossa silver technique and the epiphyseal cartilages showing intensive metachromasia with toluidine-blue staining were converted with grey-value window programs and afterwards the areas of the selected structures were measured. The histomorphological investigations showed that the murine tibiae, incubated for a period of 6 days in a medium with addition of 5 mmol mellitic acid, showed both a significant reduction of calcium deposits and an increase of epiphyseal intercellular cartilage matrix. The tibiae incubated in a medium with addition of 0.5 mmol sodium fluoride significantly showed an increase of calcium deposits in the thickened lammellae of the cornpacta. These histomorphological results confirm previous biochemical studies