Structural and Textural Modifications of Ternary Phosphate Glasses by Thermal Treatment

Phosphate-based glasses of composition xNa₂O−(45+(10−x))CaO−45P₂O₅ with different Na₂O, CaO (x = 1, 5, 10, 15, and 20 mol%), and invariable P₂O₅ (45 mol%) contents were prepared using the rapid melt quench technique. The obtained thermal data from differential thermal analysis revealed a decline in glass transition (T_g) and crystallization (T_c) temperatures of glasses against the compositional changes. The inclusion of Na₂O at the cost of CaO in the glass network led to a reduction in its thermal stability. The thermal treatment carried out on glasses helped to derive their glass-ceramic counterparts. The amorphous and crystalline features of samples were characterized using X-ray diffraction patterns. The crystalline species that emerged out of the calcium phosphate phases confirmed the dominance of Q¹ and Q² structural distributions in the investigated glass-ceramics. The obtained scanning electron micrographs and atomic force microscopic images confirmed the surface crystallization and textural modification of the samples after thermal treatment. The N₂-adsorption–desorption studies explored the reduction of porous structures due to thermal treatment on the melt-driven glass surface. The measured elastic moduli and Vicker's hardness values of the glasses showed an increase after thermal treatment, which were reduced against the inclusion of alkali content in both glass and glass-ceramics.     

Physical and optical properties of Co2+, Ni2+ doped 20ZnO + xLi2O + (30 − x)K2O + 50B2O3 (5 ≤ x ≤ 25) glasses: Observation of mixed alkali effect

Co²⁺ and Ni²⁺ ions doped 20ZnO + xLi₂O + (30 ? x) K₂O + 50B₂O₃ (5 ≤ x ≤ 25) mol% glasses are prepared using melt quenching technique. Structural changes of the prepared glasses by addition of transition metal oxides, CoO and NiO are investigated by UV–vis–NIR, FT-IR spectroscopy and XRD. The XRD pattern indicates the amorphous nature of prepared glasses. FT-IR measurements of the all glasses revealed that the network structure of the glasses are mainly based on BO₃ and BO₄ units placed in different structural groups in which the BO₃ units being dominant. The optical absorption spectra suggest the site symmetry of Co²⁺ and Ni²⁺ ions in the glasses are near octahedral. Crystal field and inter-electronic repulsion parameters are also evaluated. The optical band gap and Urbach energies exhibited the mixed alkali effect. Various physical parameters such as density, refractive index, optical dielectric constant, polaron radius, electronic polarizability and inter-ionic distance are also determined.     

The influences of some additives on electrochemical behaviour of nickel electrodes

Nickel hydroxide is used as an active material in positive electrodes of rechargeable alkaline batteries. Since the nickel hydroxide electrode exhibits a poor performance which results not only from the competitive reactions of the oxidation of the active material but also from the evolution of oxygen. Its reduced charge acceptance is suspected to be related to a relatively long distance between nickel hydroxide particles and the nearest portion of the substrate. The practical capacity of the positive nickel electrode depends on the efficiency of the conductive network connecting the Ni(OH)₂ particle with the current collector.     

Maximal load demand allocation

The authors address the problem of determining the maximum amount of active and reactive unserved load demand that can be connected to each bus in an electric power system without violation of its operating constraints. This maximal load demand allocation problem, which is associated with each electrical island of a power system operating in a restorative state, is formulated as a mixed nonlinear-integer programming problem. A decoupling procedure partitions the overall allocation problem into a maximal active load demand allocation subproblem and a minimal reactive load demand deallocation subproblem. The approach has been implemented in the form of a computer program and tested using power system models of up to 118 buses. Details of the implementation procedure and some illustrative test results are presented     

Retention of ascorbic acid in pickles — effect of different spices and salt (an in vitro study)

Effect of spices, different concentration of sodium chloride and other salts on retention of ascorbic acid during storage period (21 days in case of spices and eight days for salts) was studied. The retention of ascorbic acid with the addition of 24% NaCl was 55%, followed by 37% with red chillies, fenugreek, turmeric; 32% with the addition of pepper, sugar and 26% with mustard and asafoetida. When all the spices and salt were added together, the retention was much higher (73%) than those with individual spices. Sodium chloride over a wide range of concentrations was found to have higher retention of ascorbic acid. The retention being 80%, when stored with 24.0% sodium chloride solution for eight days. Sulfates of sodium, potassium, magnesium and manganese or chlorides of magnesium or manganese did not have a significant effect on the retention of ascorbic acid. The retention with potassium chloride was close to that observed with sodium chloride.     

Screening for bacterial vaginosis and cervicitis aimed at preventing premature delivery

BACKGROUND/AIMS: We previously reported that the populations of lymphocytes and the expression of activated antigens in human sinusoidal mononuclear cells were different from those in peripheral blood mononuclear cells. Attempts to culture these cells for further study failed because they died rapidly under standard culture conditions in vitro after isolation from the liver. In this study, we evaluated the characteristics of cell death and the effects of various culture conditions on the viability of these cells. METHODS: Sinusoidal mononuclear cells were isolated from University of Wisconsin solution that had been perfused through the portal veins of normal healthy human livers harvested for transplantation into living related recipients. RESULTS: 70% of sinusoidal mononuclear cells cultured in vitro were nonviable within 48 h after isolation, while only 10% of peripheral blood mononuclear cells died under the same conditions. Sinusoidal mononuclear cells showed DNA ladder formation of DNA on electrophoresis and characteristic morphological pattern on electron microscopic examination that suggested they had died in an apoptotic manner. The addition of human liver extracts or 2-mercaptoethanol and reduced glutathione to the cultures rescued the sinusoidal mononuclear cells from apoptosis. Furthermore, diamide, a sulfhydryl group specific oxidant, negated the effect of the liver extract. CONCLUSION: In comparison with peripheral blood mononuclear cells, human sinusoidal mononuclear cells were more subject to death by apoptosis ex vivo, which was reversed by exogenous agents producing reducing conditions. These results suggested that hepatic sinusoidal mononuclear cells might express a different sensitivity to redox environment than peripheral blood mononuclear cells.     

Three-dimensional thermal model for vertical direct chill slab casting process

To aid in the designing of an automatic control system, a steady state three-dimensional (3D) thermal model is developed to predict the temperature distributions for an industrial scale vertical direct chill (DC) slab caster for aluminium alloy AA-1050. A single domain approach for the liquid, mushy and solid regions is used by employing the enthalpy porosity technique. The convective heat transfer in the liquid region is taken into account by assuming a slag flow velocity field equal to the casting speed. The predicted thermal field is verified with the numerically predicted temperature field available in the literature and a reasonably good agreement is found. Detailed parametric study is carried out by varying important parameters of this process. Results of the temperature field, sump depth, mushy zone thickness, shell thickness and local surface heat flux are presented and discussed.

Afin d’aider à la conception d’un système de contrôle automatique, on a développé un modèle thermique à 3D en régime permanent pour la prédiction des distributions de température d’une machine de coulée verticale de brames par refroidissement intense et continu (DC) à l’échelle industrielle, pour l’alliage d’aluminium AA-1050. On utilise une approche à domaine unique pour la région liquide, la région pâteuse et la région solide au moyen de la technique d’enthalpie et porosité. On tient compte du transfert de chaleur par convection dans la région liquide en assumant un champ de vitesse d’écoulement de laitier égal à la vitesse de coulage. On vérifie le champ thermique prédit au moyen du champ de température prédit numériquement dans la littérature et l’on obtient un accord raisonnable. On effectue une étude paramétrique détaillée en faisant varier les paramètres importants de ce procédé. On présente et discute les résultats du champ de température, de la profondeur du refoulement, de l’épaisseur de la zone pâteuse, de l’épaisseur de la coquille, et du flux thermique local à la surface.     

Functional characterization of a H+/nucleoside co-transporter (CaCNT) from Candida albicans,a fungal member of the concentrative nucleoside transporter (CNT) family of membrane proteins

Human and other mammalian concentrative (Na(+)-linked) nucleoside transport proteins belong to a membrane protein family (CNT, TC 2.A.41) that also includes Escherichia coli H(+)-dependent nucleoside transport protein NupC. Here, we report the cDNA cloning and functional characterization of a CNT family member from the pathogenic yeast Candida albicans. This 608 amino acid residue H(+)/nucleoside symporter, designated CaCNT, contains 13 predicted transmembrane domains (TMs), but lacks the exofacial, glycosylated carboxyl-terminus of its mammalian counterparts. When produced in Xenopus oocytes, CaCNT exhibited transport activity for adenosine, uridine, inosine and guanosine but not cytidine, thymidine or the nucleobase hypoxanthine. Apparent K(m) values were in the range 16-64 micro M, with V(max) : K(m) ratios of 0.58-1.31. CaCNT also accepted purine and uridine analogue nucleoside drugs as permeants, including cordycepin (3'-deoxyadenosine), a nucleoside analogue with anti-fungal activity. Electrophysiological measurements under voltage clamp conditions gave a H(+) to [(14)C]uridine coupling ratio of 1 : 1. CaCNT, obtained from logarithmically growing cells, is the first described cation-coupled nucleoside transporter in yeast, and the first member of the CNT family of proteins to be characterized from a unicellular eukaryotic organism.