Thermal and structural properties of KPO3·Ln(PO3)3 glasses (Ln=rare earth ion)

Glass transition temperatures T_g and Raman spectra of KPO₃·Ln(PO₃)₃ (Ln=rare earth ion) glasses were measured for all rare earth members (except Pm). From the series behavior of the T_g and Raman data, it is concluded that the coordination number around rare earth ions changes, probably from nine to eight, in the middle of the rare earth series.     

Precise Measurements of the Vapor-Liquid Equilibria (VLE) of HFC-32/134a Mixtures Using a New Apparatus

A new apparatus for precise measurements of the vapor-liquid equilibria of mixtures by the circulation method has been developed. This apparatus has two special components: a high-stability temperature control system and a helium pressurization system. The temperature in the liquid bath surrounding the sample cell is kept constant within ±0.5mK. The helium pressurization system increases the pressure of the sampled mixture when measuring the compositions at low temperatures by gas chromatography. With these components, the uncertainty in measuring the vapor-liquid equilibria has been reduced. Using this apparatus, the vapor-liquid equilibria of HFC-32/134a mixtures were measured in a temperature range of 263.15 to 293.15K. These results are in good agreement with the calculated results from REFPROP (Ver. 6.01) with a relative pressure difference of about 2%.     

Environmental remediation by an integrated microwave/UV illumination technique. 8. Fate of carboxylic acids, aldehydes, alkoxycarbonyl and phenolic substrates in a microwave radiation field in the presence of TiO2 particles under UV irradiation

Thermal and nonthermal effects originating when a system is subjected to a microwave radiation field in the TiO2-photocatalyzed transformation of model substances containing various functional groups (e.g., benzoic acid, phthalic acid, o-formylbenzoic acid, phthalaldehyde, succinic acid, dimethyl phthalate, diethyl phthalate, and phenol) have been examined under simultaneous irradiation by ultraviolet (UV) and microwave (MW) radiations. Characteristics of the microwave effects and the fate of each substrate during the microwave-assisted photocatalytic process were monitored by UV absorption spectroscopy, HPLC methods, total organic carbon assays, and identification of intermediates using electrospray mass spectral techniques. Microwave thermal and nonthermal effects were delineated by comparing results from MW-generated internal heat versus conventional external heating, and at constant ambient temperature under a microwave field. Factors involved in the nonthermal component of the microwave radiation were inferred for the initial adsorption of the substrate and its subsequent degradation occurring on the surface of TiO2 particles. Microwave effects bear on the mechanism through which a model substrate undergoes oxidative degradation. A characteristic feature of these effects was briefly examined by considering the behavior of polar (dipole moments) substrates in a microwave radiation field.     

Dependence of Superconducting Critical Temperature of A15-Type V3Ga on Composition

The composition dependence of the superconducting critical temperature T _c has been investigated for A15-type V₃Ga compounds. The T _c is determined by the specific heat and the magnetic flux transmission ratio through the sample and discussed in terms of the powder X-ray diffraction. The long-range order parameter and the lattice parameter of V₃Ga are evaluated quantitatively by the Rietveld method at each composition, which is evaluated exactly by the electron probe microanalysis (EPMA) measurements. The well-ordered homogeneous alloying structures. V _1–x Ga _x compounds are found to have nearly the same T _c as that for the stoichiometric composition between 0.23<0.25.     

Synthesis and characterization of half-sandwich Ir and Ru complexes containing Mnt ligand (Mnt = maleonitriledithiolate)

The reaction of [Cp¹IrCl₂]₂ and [(p-Cymene)RuCl₂]₂ with disodium maleonitriledithiolate (Na₂Mnt) yield the 16-electron complexes Cp¹Ir(Mnt) (1) and [(p-Cymene)Ru(Mnt)] (2). Complexes 1 and 2 can further react with PPh₃ to form the corresponding 18-electron complexes Cp¹Ir(Mnt)PPh₃ (3) and [(p-Cymene)Ru(Mnt)PPh₃] (4). All complexes have been fully characterized by IR and NMR spectroscopy, as well as elemental analysis. The molecular structures of 1 and 4 have been confirmed by X-ray crystallography.     

Determination of the thermal conductivity of argon and nitrogen over a wide temperature range through data evaluation and shock-tube experiments

Reliable and well-established methods to measure the thermal conductivity of gases are available only in the moderate temperature range, namely, up to about 1000 K. In the present study, a set of the most probable thermal conductivity values of components of gaseous combustion products in a wide range of temperatures has been obtained through an optimum combination of three procedures: critical assessment of available data in the moderate temperature range, experimental determination by the shock-tube method at high temperatures, and theoretacal estimation of temperature dependence in the intermediate temperature range. Among the components of combustion products, one monatomic gas and one diatomic gas, namely, argon and nitrogen, were studied in the present paper. The shock-tube measurements have been performed in the temperature ranges 1000–4500 K for argon and 500–2200 K for nitrogen. The results of the critical evaluation and the shock-tube measurements have been combined with the aid of theoretically assumed temperature dependence of the thermal conductivity.Invited paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Enzymatic digestion of corncobs pretreated with low strength of sulfuric acid for bioethanol production

In this study, the effect and the optimum pretreatment condition of corncobs using low strength of H₂SO₄ were investigated, in which H₂SO₄ was used to improve the enzymatic digestibility of corncobs for saccharification without degradation of sugars released. The optimum pretreatment condition was found to be the addition of 0.5% (vol./vol.) H₂SO₄ and autoclaving at 122 °C for 20 min. Under this condition, the structural integrity of corncob was altered to make cellulose microfibrils more accessible for cellulase enzymes, and the enzymatic digestion of corncobs could be significantly enhanced. A high yield of sugar, 80% (wt./wt.), could be obtained at a low enzyme dosage of 0.024 g enzymes/g cobs, when pretreated. As a result, the ethanol production was obviously improved by the pretreatment, i.e., the ethanol yield of 77% (wt./wt.) was obtained within 36 h in the SSF fermentation using Saccharomyces cerevisiae NBRC2114.     

Laser spark initiated microwave discharge

The process of laser-spark-assisted initiation of microwave (MW) discharge in the free space has been experimentally studied. It is established that a threshold for laser-spark-initiated MW discharge at atmospheric pressure decreases in a broad range of MW pulse delay times relative to the laser pulse. At a reduced air pressure, MW discharge can be laser-initiated in the absence of spark.