Structural Characteristics and Electrical Conductivity of Vanadium-doped lithium Ultraphosphate Glasses

Glasses of the 33.5Li₂O-66.5P₂O₅-xV₂O₅ (mol. %) system with (0 ≤ x ≤ 5) were prepared by the normal melting and annealing technique. Their physical and spectroscopic properties such as X-ray powder diffraction (XRD), density, infrared spectroscopy and electrical conductivity were investigated. The composition dependent density shows an initial decrease at 0.1 mol.% of V₂O₅ followed by an increase in density with further addition of the V₂O₅ content. The structure of these glasses has been studied by recording the Fourier-transform infrared spectroscopy (FTIR) over the range 400–1800 cm^?1. Vibrational modes are assigned to different types of phosphate groups in the glass network. The temperature (333–452 K) and composition dependence of direct current (DC) electrical conductivity were measured. The electric conductivity is observed to increase with the first addition of vanadium oxide reflecting the presence of V⁴⁺ions that take part within modifying positions in the glass network .Then, the electric conductivity is found to decrease with the further increase in the content of V₂O₅ up to 5 mol.% reflecting the formation of V⁵⁺ions that take part as network forming positions in the glass network. The variations in density and electrical conductivity with V₂O₅ content are discussed in terms of changes in the glass structure.     

Solubility of Sodium Phenytoin in Ethanol + Water Mixtures at Various Temperatures

The solubility of sodium phenytoin in binary mixtures of ethanol + water at 298.2, 303.2, 308.2, and 313.2 K was measured. The solubility was increased by addition of ethanol, reached a maximum value at 0.50 mass fraction of ethanol, and then decreased with further increase of ethanol. At all temperatures, the solubility of the solute in neat water was greater than that of neat ethanol. The Jouyban–Acree model and its combined version with the van't Hoff equation were used to predict the reported solubilities, resulting in a mean relative deviation of 12.7 and 13.7%, respectively.     

Chemical Durability of Fluoride Glasses: I, Reaction of Fluorozirconate Glasses with Water

The chemical durability of five flouarozirconate glass compositions was studied. Measurements of leachant composition and solution chemistry by plasma emission spettroscopy, pH, and fluoride analysis are reported. Changes in surface structure were monitored by scanning electron microscopy, electron-probe X-ray analysis, and X-ray diffraction. The modifer additives with high aqueous solubility (A1F₃, NaF, LiF, PbF₂) exhibited the highest leach rates with ZrF₄, BaFs₂, and LaF₃ exhibiting lower rates. The leaching order of Zr > Ba > La was maintained for all samples. The leaching process consists of the dissolution of the glass matrix, leaving a thick and porous layer containing Zr, Ba, La, and molecular water. Hydroxylation of the Zr species to form a hydroxyfluoride complex in solution dominated a decrease in pH to moderately acidic values. The resulting increase in component solubility (particularly zirconium fluoride) in the acidic solutions accelerated the glass dissolution rate and demonstrated that, if no buffer is present to avert the pH drift, the chemical durability of these glasses in aqueous environments is extremely poor, being roughly equivalent to that of Na₂O 2SiO₂.     

Chemical Durability of Fluoride Glasses: II, Reaction of Barium-Thorium-Based Glasses with Water

The aqueous leaching behavior of three Ba-Th-based fluoride glasses was studied. Results of solution analysis, SEM, and IR spectroscopy are reported and compared with earlier studies on fluorozirconate-based glasses. Leaching appears to be by matrix dissolution dominated by component solubility. No hy-drated leach layer was seen to form on the surface. Only a mild drift In solution pH, resulting from a limited hydrolysis of, dissolved thorium fluoride, was observed. The reduced pH drift away from neutral, coupled with lower component solubilities, is credited with the 100-fold improvement in chemical durability of the Ba-Th-based fluoride glasses over the fluorozirconate-based glasses reported previously.     

Mechanical Properties of Chemically Strengthened Glasses at High Temperatures

Young's modulus, shear modulus, and modulus of rapture for two chemically strengthened glasses were determined at high temperatures. The Young's modulus and shear modulus decreased with increasing temperature, with a sharp inflection slightly above room temperature. The region of inflection indicated an internal friction peak. For comparison Young's modulus and shear modulus were determined as a function of temperature on a thermally tempered soda-lime-silica glass and on a semitempered borosilicate glass. Curves of these moduli, in contrast to those for the chemically strengthened glasses, did not reveal regions of inflection. The modulus of rupture is not affected by short exposure to heat up to 260°C., but decreases appreciably when exposed to temperatures above 204°C for 200 hr or more. Deflection measurements at room temperature showed that the two chemically strengthened glasses had about five times as much delayed elasticity as did thermally tempered soda-lime-silica glass.     

Reactions of Glasses with Aqueous Solutions

The kinetics of the reactions of various glasses with water and aqueous solutions with pH from 1 to 13 was studied. Simple binary alkali oxide-silica glasses were examined as well as some ternary glasses derived from the binary compositions by substituting alkaline-earth oxides for silica. All components of the glass were determined in the extract; the glasses varied from those very easily decomposed by water to those having durability comparable to that of commercial glasses. The equilibrium conditions of the system glass-water are distinguished from the approach to that equilibrium normally observed in such experiments. The rates of removal of various glass constituents under varied experimental conditions are reported and potential mechanisms for these reactions are discussed.     

Thermal Stability of Immobilized Lipase from Candida antarctica in Glycerols with Various Water Contents at Elevated Temperatures

The immobilized lipase from Candida antarctica (fraction B, CALB) was incubated in glycerols with various water contents at 80–100 °C to measure the residual activity as a function of time. The glycerol-containing water stabilized the immobilized CALB, especially at 30–60 wt% water contents. The thermal inactivation behaviors of the immobilized CALB were expressed by a model in which the free energy of activation for the inactivation of the immobilized lipase molecules obeyed a Gaussian distribution.     

Reactions of Zirconia and Titanium at Elevated Temperatures

The reactions between zirconia and titanium were studied by (1) weight change and bulk density determinations, (2) chemical analysis, (3) metallographic and petrographic analyses, (4) microhardness determinations, (5) lattice parameter measurements, (6) electron probe analysis, and (7) thermal conductivity determinations. These studies were made on specimens which had been fired in vacuum in the temperature range 1200° to 2000°C. Experimental data indicated that titanium contents up to 4 atomic % were retained at room temperature as a substitutional solid solution in zirconia. In titanium-rich binary alloys, zirconium and oxygen were retained in solid solution in titanium for zirconia contents up to approximately 10 mole %. In this case, the zirconium entered the titanium lattice substitutionally and the oxygen went into interstitial positions.     

Study of the Physical Properties of Metallic Glasses at Cryogenic Temperatures

The problems of using metallic glasses for fabricating magnetic cores of cryogenic and superconducting electrotechnical devices, operating at low temperatures of 77 K, are considered. The experience of creating a number of devices, including electric generators, motors and transformers with HTSC windings, is analyzed. The advantages and disadvantages of magnetic cores from annealed tapes are considered. The results of the study of losses and magnetic characteristics of domestic amorphous and nanocrystalline alloys before and after high-temperature annealing are presented.     

Platelet Hemostasis Reactions at Different Temperatures Correlate with Intracellular Calcium Concentration

Hypo- and hyperthermia affect both primary and secondary hemostasis; however, there are controversial data concerning platelet activation and the underlying mechanisms under hypo- and hyperthermia. The discrepancies in the data could be partly explained by different approaches to hemostatic reactions analysis. We applied a new LaSca-TMF laser particle analyzer for a simultaneous fluorescence and laser scattering analysis of platelet responses at different temperatures. Human platelets were activated by ADP in a wide range of temperatures, and platelet transformations (e.g., a shape change reaction, aggregation and clot formation) and the intracellular calcium concentration ([Ca²⁺]_i) were analyzed by LaSca-TMF and confocal microscopy. The platelet shape change reaction gradually increased with a rising temperature. The platelet aggregation strongly decreased at low ADP concentrations with the augmentation of the temperature and was independent of the temperature at high ADP concentrations. In contrast, the clotting time decreased with a temperature increase. Similar to the aggregation response, a rise in [Ca²⁺]_i triggered by low ADP concentrations was higher under hypothermic conditions and the differences were independent of the temperature at high ADP concentrations. We showed that the key reactions of cellular hemostasis are differentially regulated by temperature and demonstrated for the first time that an accelerated aggregation under hypothermic conditions directly correlated with an increased level in [Ca²⁺]_i in platelets.     

Formation of Radiation-Induced Defects in Silica Glasses at High Irradiation Temperatures

The mechanisms of formation of radiation-induced defects in silica glasses are investigated under both simultaneous and sequential exposure to -radiation and high temperatures. It is demonstrated that silica glasses contain E"(T) centers (T = Si and Al) in impurity-free regions andE"_M (T) centers in the vicinity of alkali metal impurities. These centers can undergo transformations. The origin of a new center responsible for the absorption band at 360 nm is elucidated. This center is identified as a twofold-coordinated aluminum atom with a trapped electron.     

Elastic Moduli of Glasses at Elevated Temperatures by a Dynamic Method

The elastic constants of thirteen glasses were measured by a dynamic method at elevated temperatures. Both Young's modulus and the shear modulus were determined and from these Pois-son's ratio was calculated as a function of temperature. Fused silica, Vycor-brand glass, and Pyrex-brand glass had positive temperature coefficients of elastic moduli, whereas all the other glasses showed negative coefficients. Poisson's ratio was found to rise with temperature in all thirteen glasses. This is interpreted as an indication of an approach to the liquid state.     

MgO-C耐火材料在不同温度下于空气中的氧化机理

在空气中,于800－1600℃的不同温度下,定期采用测量重量损失的方法对含20％（质量）石墨MgO-C耐火材料的氧化进行了研究。随着温度从800℃升高到1400℃,脱碳率提高,然后从1400℃－1600℃或多或少保持恒定。详细地分析了氧化动力学,并且从800℃-1400℃的湿度范围得到了反应速度模型,发现可以通过脱碳层的氧护散来控制反应速度。在较高的温度（＞1400℃）下,通过MgO(固）＋C（固）→Mg(气）＋CO(气）反应间接地发生石墨氧化,这样产生的镁气体在耐火材料的外表面再发生氧化,并作为MgO沉积。这会导致在脱碳的外壳中气孔率降低,结果氧化速度放慢。     

不同温度培养的3株EV71毒株的增殖动力学分析

目的对不同温度培养的3株EV71中国流行株的增殖动力学进行分析。方法分别在32、35、37和40℃条件下对FY23、K9和S1株EV71进行传代培养、2～24h培养及噬斑培养,采用微量滴定法测定病毒的感染性滴度;传代培养的子代病毒通过脑内注射方式感染新生ICR乳鼠,观察病毒的致病性。结果传代培养时,在32和40℃培养的3株病毒致细胞完全病变时间较35和37℃延长,且子代病毒滴度下降,35℃培养的病毒滴度较37℃升高;3株病毒培养24h后,37℃培养的病毒增殖效率最高,35℃次之,40℃最低;4个温度培养的病毒噬斑形态无明显变化;新生乳鼠脑内注射致死率差异无统计学意义(P>0.05)。结论培养温度的变化可影响EV71的致细胞病变速度及子代病毒的增殖,但对病毒噬斑的形态及新生乳鼠的致病能力无明显影响。     

化学反应中水分的控制方法

本文针对去除化学反应中水分的影响因素,从固体原料,液体原料,溶剂,反应设备,空气中的水分及反应生成水等方面制定措施加以控制.对原料制定水分标准,进行干燥或进行脱水操作,对设备进行干燥,使用干燥的惰性气体进行保护,对生成的水分进行共沸或反应进行去除等措施提供可参考的建议.     

Glasses Resistant to Sodium Vapor at Temperatures to 700°C

Glasses resistant to attack by sodium vapor at temperatures up to 700°C were developed from the CaO-Al₂O₃-MgO-BaO-B₂O₃ system. The resistance of these glasses decreases sharply above the transformation temperature. The glasses have a high water content, have good wetting properties, and adhere well to materials such as aluminum oxide and niobium; thus they can be used as solder glasses and metalizing components. The surface layer formed on the glass during attack by sodium vapor has a specific electrical resistance which is lower by 2 to 3 orders of magnitude than that of glass not exposed to sodium vapor.     

Photoionization of Ferrocyanide at Various Wavelengths in Polar Glasses at 77°K

Solutions of potassium ferrocyanide in 10 N NaOH glass and in ethylene-glycol/water (3/1) glass at 77°K were irradiated with UV-light. The ratio of the yields of radicals in the two solvents, as well as the scavenging efficiency of an election scavenger (acrylamide) in 10 N NaOH, were found to change with the irradiation wavelength. From the experiments the conclusion is drawn that the ejection of electrons may occur from different electronic levels depending on the excitation wavelength and that the electrons ejected from a charge-transfer-to-solvent state have higher reactivity with a scavenger than electrons ejected from intramolecular singlet states.     

Influence of Polydimethylsiloxane on the Oxygen Concentration of Oils at Various Temperatures

The effect of temperature on the oil oxygen concentration, tested in both soybean and olive oils with no added polydimethylsiloxane (PDMS), showed that the oxygen concentration increased with temperature to approximately 100 °C. Above 100 °C, the oxygen concentration abruptly decreased. This change was attributed to the balance between the rates of oxygen uptake and consumption by oil oxidation, which favored oxygen consumption over uptake at temperatures above 100 °C. The addition of 100 ppb PDMS to soybean oil, enough to form a continuous layer over the surface of the oil, reduced the oxygen concentration when compared to a soybean oil control containing no added PDMS at temperatures ranging from 93 to 180 °C; thus suggesting an oxygen barrier effect of PDMS. The accumulation of PDMS at the air–oil interface in soybean oil held at 180 °C was determined by comparing the oil’s internal temperature and the apparent surface temperature. A decrease in the apparent surface temperature while the oil was held at a constant internal temperature was attributed to a change in the emissivity of the surface as a consequence of the accumulation of PDMS in the air–oil interface. The presence of PDMS at the air–oil interface was confirmed for 100 ppm of PDMS, a concentration greater than the concentration necessary to form a monolayer of PDMS on the oil surface.     

Oxyfluoronitride Glasses with High Elastic Modulus and Low Glass Transition Temperatures

The preparation and properties of novel calcium aluminosilicate glasses containing both nitrogen and fluorine are reported. Nitrogen increases Young's modulus and microhardness of oxide glasses by ∼25%. However, one of the major disadvantages of the use of oxynitride glasses for high-stiffness applications is the fact that nitrogen also increases glass viscosity. Melting temperatures of the order of ∼1700°C are required to achieve sufficiently low viscosities for glass forming and drawing processes. Fluorine substitution for oxygen in Ca–Si–Al–O–N glasses yields significant decreases in glass transition temperature and glass melting temperature as well as increasing nitrogen solubility to levels much higher than that previously reported for glasses made by melting CaO, SiO₂, Si₃N₄, and Al₂O₃ powder mixtures. The important effect that N results in increased elastic modulus is not diminished by the addition of fluorine. Thus, it is possible to produce novel oxyfluoronitride glasses with a high elastic modulus but melting and working can be carried out at more conventional glass processing temperatures.