Ab-initio calculations of the optical properties of the Si(113)3x2ADI surface

We investigated the stable silicon (113) surface with a 3x2ADI reconstruction by ab-initio methods. The ground state properties have been obtained using the density-functional theory. We present the dispersion of the electronic band structure, where the surface bands have been distinguished from the projected bulk bands by calculating their localization in the slab. The optical spectra, here the reflectance anisotropy (RAS), have been obtained within the independent particle random phase approximation. We identified surface features in the spectra tracing them back to the responsible electronic states and, studied their localization in the slab. A comparison with available experimental data for the band structure and the RAS shows a good agreement.Comment: 10 pages, 10 figure

Elementary structural building blocks encountered in silicon surface reconstructions

Driven by the reduction of dangling bonds and the minimization of surface stress, reconstruction of silicon surfaces leads to a striking diversity of outcomes. Despite this variety even very elaborate structures are generally comprised of a small number of structural building blocks. We here identify important elementary building blocks and discuss their integration into the structural models as well as their impact on the electronic structure of the surface

An improved method for the determination of sulphachloropyrazine in meat and liver of broilers during and after their treatment for coccidiosis

The paper presents results of the HPLC determination of sulphachloropyrazine residues (active component of the drug „Esb3 30%”) in muscle tissue and liver of broiler chickens inoculated with laboratory-grown coccidium in the course and after treatment with this sulphonamide.Extraction of sulphachloropyrazine from samples of broiler muscle tissue and liver was carried out with a mixture of solvents dichloromethane-methanol-acetic acid (90:5:5, v/v/v), followed by extract purification by chromatographic separation on a XAD-2 column and elution of sulphachloropyrazine residues with dichloromethane. The HPLC determination of sulphachloropyrazine residues was accomplished on a Bio Sil C-8 HL 5 ?m column with a mobile phase consisting of 60% aqueous solution of acetonitrile and NH3 (pH=9.5), using a UV detector at 254 nm.The method developed allows quantitative determination of the residues of the anticoccidial agent in broiler tissue samples with a detection limit of 0.02 ?g g–1. Recovery of the method for this type of samples with a complex matrix was satisfactory, the results ranging from 79.2(0.6 to 86.7(0.2% for muscle tissue and from 81.7(0.8 to 87.3(0.7% for liver

Rate of lipid peroxidation in brain and liver tissues and the total antioxidant status of blood plasma in developing chicks

Age-related changes of tissue lipid peroxidation (LPO) of liver and brain, as well as plasma antioxidant capacity of broiler chicken cockerels were investigated. Tissue LPO was characterised by the spectrophotometric assessment of thiobarbituric acid reactive substances (TBARS). Plasma antioxidant power was evaluated by the measurement of total antioxidant status (TAS). Newly hatched broiler chicks had similar TAS value (1.19 mmol/l) as newborns of mammalian species. Significant changes (p < 0.05) were observed in the time course of all parameters. Tissue TBARS concentration was higher in the brain than in the liver at hatching, while the latter organ was found to have more effective antioxidant defence during embryonic life. The concentration of TBARS increased up to the 10th day in the liver but only up to the 21st day in the brain, and the former was accompanied by an approximately 50% decrease of plasma antioxidant capacity. This suggests that the liver plays an important role in forming the antioxidant defence mechanisms of the blood plasma in broiler chicks

Dog feeding test for assessing the nutritional adequacy of practical diets

The nutritive value of dog foods declared by the manufacturer as nutritionally complete and balanced can be best assessed by feeding trials with dogs. A protocol of a feeding trial has been developed and tested with working dogs fed two different commercial complete and balanced diets for 8 weeks. The parameters used for evaluating the effect of diets were general health status, body and hair coat condition, change of body weight, haematological parameters (white blood cell (WBC) count, red blood cell (RBC) count, haemoglobin, packed cell volume), and biochemical parameters in blood serum (alanine aminotransferase, urea, albumin). The trial protocol proved to be appropriate to monitor the dogs' nutritional status and to reveal differences between diets. This method of evaluation is recommended for use in supporting the nutritional claims (labelling) of dog foods

Effects of saturated and unsaturated fats with vitamin E supplementation on the antioxidant status of broiler chicken tissues

The influence of fish oil (highly unsaturated) and beef tallow (highly saturated) with vitamin E (100 IU/kg) supplementation on the antioxidant status of broiler chicken cockerels was investigated. Chicks were fed a control diet with no added fat, 40 g/kg each of fish oil and beef tallow diets, respectively, from 11 to 42 days of age. Tocopherol concentration and the rate of lipid peroxidation, thiobarbituric acid reactive substance (TBARS) in liver, fatty acid composition of the liver lipids, blood serum total antioxidant status (TAS), and reduced glutathione (GSH) content were determined. Vitamin E supplementation of the diet increased liver ?-tocopherol content in chicks regardless of the type of dietary fat. Fish oil diet resulted in higher liver TBARS value while beef tallow diet showed lower values compared to the control diet. Vitamin E supplementation reduced liver TBARS as well as serum GSH, and raised serum TAS for all diets. Serum GSH was the same for vitamin E supplemented diets regardless of the fat supplement. Fish oil diets resulted in a significant increase in hepatic lipid n-3 PUFA content. A significant positive correlation was found between liver TBARS and n-3 PUFA content. No relationships were established, however, between liver TBARS and n-6 PUFA or saturated fatty acids. The results suggest that feeding oils rich in n-3 PUFA increases tissue concentration of these fatty acids, consequently increasing tissue lipid peroxidation and reducing the antioxidative status of broiler chickens. Supplementing high levels of vitamin E with such oils may increase tissue oxidative stability. Serum TAS or GSH may be used as a measure of antioxidative status in chickens

Inelastic response of silicon to shock compression

The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature