Chloromycetin in the nutrition of the silkworm Bombyx mori L.-III. Influence on gut weight, oxygen uptake, and glucose absorption

Administration of chloromycetin has been found to enhance the oxygen uptake of the gut of the silkworm. The possibility that this increase might have been due to a thinning of the gut wall has been ruled out since the reduction in gut weight set in much later. Although glucose ultilization by the gut has been found to be increased in vitro, increase in oxygen uptake has not been affected in the presence of glucose. The possibility of a hormonal stimulation has been discussed.

Isolation and partial characterization of sheep plasma α1-mucoprotein

1. 1. Sheep plasma α1-mucoprotein was isolated in an electrophoretically homogeneous state by a combination of ammonium sulphate saturation, isoelectric precipitation and preparative agar electrophoresis in a yield of approx. 150 mg/l of plasma. 2. 2. The mucoprotein was water-soluble, non-coagulable on heating at 100°, not precipitable by 1.8 M perchloric acid, 10% trichloroacetic acid but precipitable by saturated ammonium sulphate solution, 0.6 M sulfosalicylic acid and 5% phosphotungstic acid in 2 N HCl. It had E1 cm1 % value of 9.57 at 278 mμ in water, refractive-index index increment 1.9·10-4 (g/l) in water, isoelectric point at pH 4.45 (sodium acetate-acetic acid buffer) and was homogeneous in pH range 4.0-11.5 but at pH values 2.6 and 3.5 showed some dissociation. 3. 3. The mucoprotein had the following chemical composition: Nitrogen, 12.4%; polypeptide, 77.4%; total hexose (only mannose and galactose), 7.1%; fucose, 1.0%; glucosamine, 4.9% and sialic acid, 4.8%. It had no N-terminal amino acid.

Photocatalytic Activity of Microwave Plasma-Synthesized TiO2 Nanopowder

Nanocrystalline TiO2 was synthesized using the microwave plasma technique and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, laser particle size analyzer, UV-vis spectroscopy and BET surface area analyzer. The synthesized TiO2 powder crystallized in anatase phase and the crystallite sizes were in nanometers. The photocatalytic activity of the compound was determined and compared against the activity of the commercial Degussa P-25 TiO2 catalyst. The degradation rates of the dyes were found to be higher over the synthesized TiO2 as compared to that over commercial Degussa P-25 TiO2.

Optimal Blood Glucose Regulation using Single Network Adaptive Critics

Diabetes is a serious disease during which the body's production and use of insulin is impaired, causing glucose concentration level toincrease in the bloodstream. Regulating blood glucose levels as close to normal as possible, leads to a substantial decrease in long term complications of diabetes. In this paper, an intelligent neural network on-line optimal feedback treatment strategy based on nonlinear optimal control theory is presented for the disease using subcutaneous treatment strategy. A simple mathematical model of the nonlinear dynamics of glucose and insulin interaction in the blood system is considered based on the Bergman's minimal model. A glucose infusion term representing the effect of glucose intake resulting from a meal is introduced into the model equations. The efficiency of the proposed controllers is shown taking random parameters and random initial conditions in presence of physical disturbances like food intake. A comparison study with linear quadratic regulator theory brings Out the advantages of the nonlinear control synthesis approach. Simulation results show that unlike linear optimal control, the proposed on-line continuous infusion strategy never leads to severe hypoglycemia problems.

Computer modelling approach to study the modes of binding of alpha- and beta-anomers of D-galactose, D-fucose and D-glucose to L-arabinose-binding protein

The modes of binding of alpha- and beta-anomers of D-galactose, D-fucose and D-glucose to L-arabinose-binding protein (ABP) have been studied by energy minimization using the low resolution (2.4 A) X-ray data of the protein. These studies suggest that these sugars preferentially bind in the alpha-form to ABP, unlike L-arabinose where both alpha- and beta-anomers bind almost equally. The best modes of binding of alpha- and beta-anomers of D-galactose and D-fucose differ slightly in the nature of the possible hydrogen bonds with the protein. The residues Arg 151 and Asn 232 of ABP from bidentate hydrogen bonds with both L-arabinose and D-galactose, but not with D-fucose or D-glucose. However in the case of L-arabinose, Arg 151 forms hydrogen bonds with the hydroxyl group at the C-4 atom and the ring oxygen, whereas in case of D-galactose it forms bonds with the hydroxyl groups at the C-4 and C-6 atoms of the pyranose ring. The calculated conformational energies also predict that D-galactose is a better inhibitor than D-fucose and D-glucose, in agreement with kinetic studies. The weak inhibitor D-glucose binds preferentially to one domain of ABP leading to the formation of a weaker complex. Thus these studies provide information about the most probable binding modes of these sugars and also provide a theoretical explanation for the observed differences in their binding affinities.

Vitamin A and thyroxine carrier proteins in chicken plasma Steady-state control of the plasma level of free retinol-binding protein and free thyroxine

1. 1. The binding parameters of prealbumin-2 with retinol-binding protein and thyroxine (T4) revealed the existence of distinct and multiple sites for both retinol-binding protein and T4. 2. 2. From the analysis of binding parameters of retinol-binding protein with prealbumin-2 it is clear that under steady-state conditions about 99% of the holo-retinol-binding protein remains bound to prealbumin-2. 3. 3. Equilibrium dialysis studies on binding properties of thyroid hormones with prealbumin-2 revealed that it has a single high affinity site and three low affinity sites. 4. 4. The occurrence of three carrier proteins for thyroid hormones, thyroxine-binding globulin, prealbumin-2 and albumin has been demonstrated. However, the chicken thyroxine-binding globulin differs from human thyroxine-binding globulin by being relatively less acidic and occuring at a two-fold lower concentration. But the thyroid hormone binding parameters are comparable. 5. 5. Highly sensitive methods were developed for determination of T4 binding capacities of the various proteins and plasma level of total T4 by fractionation of carrier proteins and further quantitatively employing in electrophoresis and equilibrium dialysis. 6. 6. The thyroxine-binding proteins were found to be two types, one (viz., thyroxine-binding globulin) of great affinity but of low binding capacity, which mainly acts as reservoir of T4, and another (viz.,prealbumin-2) of low affinity but of high binding capacity, which can participate predominantly in the control of the free T4 pool.

An assessment of the reduction potential of hydrogen plasma

Hydrogen plasma can be used for deoxidation of functional materials containing reactive metals in both bulk and thin film forms. Since the different species in the plasma are not in thermodynamic equilibrium, application of classical thermodynamics to the analysis of such a system is associated with some difficulties. While global equilibrium approaches have been tried, with and without additional approximations or constraints, there is some ambiguity in the results obtained. Presented in this article is the application of a local equilibrium concept to assess the thermodynamic limit of the reaction of each species present in the gas with oxides or oxygen dissolved in metals. Each reaction results in a different pal tial pressure of H2O. Because of the higher reactivity of the dissociated and ionized species and the larger thermodynamic driving force for reactions involving these species, they act as powerful reducing agents. It is necessary to remove the products of reaction from the plasma to prevent back reaction and gradual approach to global equilibrium. A quantitative description using the framework of the Ellingham-Richardson-Jeffes diagrams is presented.

Simultaneous Utilization of Glucose and Sucrose by Thermophilic Fungi

The utilization of mixtures of glucose and sucrose at nonlimiting concentrations was studied in batch cultures of two common thermophilic fungi, Thermomyces lanuginosus and Penicilium duponti. The sucrose-utilizing enzymes (sucrose permease and invertase) in both fungi were inducible. Both sugars were used concurrently,regardless of their relative proportion in the mixture. At the optimal growth temperature (50C), T.lanuginosus utilized sucrose earlier than it did glucose, but at a suboptimal growth temperature (30°C) the two sugars were utilized at nearly comparable rates. The coutilization of the two sugars was most likely possible because (i) invertase was insensitive to catabolite repression by glucose, (ii) the activity and affinity of the glucose transport system were lowered when sucrose was included in the growth medium, and (iii) the activity of the glucose uptake system was also subject to repression by high concentrations of glucose itself. The concurrent utilization of the available carbon sources by thermophilic fungi might be an adaptive strategy for opportunistic growth in nature under conditions of low nutrient availability and thermal fluctuations in the environment.

Chicken prealbumin: Nature of its heterogeneity and binding of plasma retinol-binding protein and thyroid hormones

The heterogeneity of chicken prealbumin (PA) has been shown to be due to the occurrence of three different plasma proteins (PA1 PA2 and PA3). Equilibrium dialysis studies revealed that the thyroid hormones bind specifically to PA2. These hormones bind at the same site on PA2. Circular dichroism studies failed to reveal conformational changes on interaction of retinol-binding protein and thyroid hormone with PA2. Both retinol-binding protein and thyroid hormone are independently transported by PA2.

Droplet Epitaxy of InN Quantum Dots on Si(111) by RF Plasma-Assisted Molecular Beam Epitaxy

InN quantum dots (QDs) were fabricated on Si(111) substrate by droplet epitaxy using an RF plasma-assisted MBE system. Variation of the growth parameters, such as growth temperature and deposition time, allowed us to control the characteristic size and density of the QDs. As the growth temperature was increased from 100 C to 300 degrees C, an enlargement of QD size and a drop in dot density were observed, which was led by the limitation of surface diffusion of adatoms with the limited thermal energy. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to assess the QDs size and density. The chemical bonding configurations of InN QDs were examined by X-ray photo-electron spectroscopy (XPS). Fourier transform infrared (FTIR) spectrum of the deposited InN QDs shows the presence of In-N bond. Temperature-dependent photoluminescence (PL) measurements showed that the emission peak energies of the InN QDs are sensitive to temperature and show a strong peak emission at 0.79 eV.

Optimization of ion energy spread in inductively coupled plasma source designed for focused ion beam applications

The ion energy distribution of inductively coupled plasma ion source for focused ion beam application is measured using a four grid retarding field energy analyzer. Without using any Faraday shield, ion energy spread is found to be 50 eV or more. Moreover, the ion energy distribution is found to have double peaks showing that the power coupling to the plasma is not purely inductive, but a strong parasitic capacitive coupling is also present. By optimizing the various source parameters and Faraday shield, ion energy distribution having a single peak, well separated from zero energy and with ion energy spread of 4 eV is achieved. A novel plasma chamber, with proper Faraday shield is designed to ignite the plasma at low RF powers which otherwise would require 300-400 W of RF power. Optimization of various parameters of the ion source to achieve ions with very low energy spread and the experimental results are presented in this article. (C) 2010 Elsevier Ltd. All rights reserved.

Self-assembled flower-like nanostructures of InN and GaN grown by plasma-assisted molecular beam epitaxy

Nanosized hexagonal InN flower-like structures were fabricated by droplet epitaxy on GaN/Si(111) and GaN flower-like nanostructure fabricated directly on Si(111) substrate using radio frequency plasma-assisted molecular beam epitaxy. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the crystallinity and morphology of the nanostructures. Moreover, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to investigate the chemical compositions and optical properties of nano-flowers, respectively. Activation energy of free exciton transitions in GaN nano-flowers was derived to be similar to 28.5 meV from the temperature dependent PL studies. The formation process of nano-flowers is investigated and a qualitative mechanism is proposed.

The Single Langmuir Probe under Orbital-Limited Conditions in a Low-Density Collisional Plasma

The cylindrical Langmuir probe under orbital-limited conditions was used to determine the charge density in a low-density collisional plasma. The Langmuir's theory was applied to both electron and ion saturation currents in their respective accelerating regions. Present study indicates that the length of the probe significantly affects the probe characteristics. A probe of suitable length under orbital-limited conditions may be useful under the experimental conditions where the radius of the probe is much smaller than the Debye lengt.