Experimental and predicted enthalpies of mixing of mixtures formed from alcohols and sunflower oil at 298.15 K

The enthalpies of mixing of systems formed from alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol) and sunflower oil at 298.15 K are presented. Enthalpies were measured in the composition range in which the compounds were miscible. From the experimental measurements, we calculated the heat capacities of the mixtures. Several group contribution models were applied to estimate the enthalpies of mixing of these mixtures. The average deviations varied from 10 to 60%, depending on the model and compound. The best prediction in all cases was the Nitta model, with average deviations from 10 to 30%. The novelty of the work is that models of this type have not been applied previously to predict enthalpies of such large molecules, and the results of the estimates are of the same order as other types of compounds (pure compounds of small size).     

Negative-bias temperature instability cure by process optimization

Negative-bias temperature instability (NBTI) is a major challenge for modern integrated circuits and may represent a key factor for the success of a technology. In this paper, NBTI is approached from a process point of view, providing a general picture of the manufacturing process steps that affect NBTI performance. It is found that several process steps may be optimized to reduce the NBTI susceptibility of p-type MOSFETs. The choice of the cure approach depends on the device application, on the technology, and also on the equipment.     

1.55-/spl mu/m spot-size converter integrated laser diode with conventional buried-heterostructure laser process

A 1.55-/spl mu/m spot-size converter integrated laser diode is demonstrated with conventional buried-heterostructure laser process. For the spot-size converter, we employed a double-waveguide structure in which a ridge-based passive waveguide was incorporated. The passive waveguide was optically combined with a laterally tapered active waveguide to control mode size. The threshold current was measured to be 5 mA together with high slope efficiency of 0.45 W/A. The beam divergence angles in the horizontal and vertical directions were as small as 9.0/spl deg/ and 7.8/spl deg/, respectively.     

Diuresis and natriuresis produced by long term administration of a selective Angiotensin-(1-7) antagonist in normotensive and hypertensive rats

Intrarenal arterial infusion of endothelin-1 (1, 3 and 10 ng/kg per min) reduced renal blood flow, urine flow rate and urinary Na+ excretion without affecting fractional Na+ excretion in anesthetized rabbits. An endothelin ET(A) receptor antagonist (R)2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]carbonyl]amino-4-me thyl-pentanoyl]amino-3-[3-(1-methyl-1H-indolyl)]propionyl]amino-3-(2-pyr idyl)propionic acid (FR139317, 1 microg/kg per min) attenuated the endothelin-1 (1 ng/kg per min)-induced renal responses. An endothelin ET(B) receptor antagonist N-cis 2,6-dimetylpiperidinocarbonyl-L-gamma-metylleucyl-D-1-met hoxycarbonyltryptophanyl-D-norleucine (BQ-788, 1 microg/kg per min) potentiated the endothelin-1-induced changes in renal blood flow, urine flow rate and urinary Na+ excretion. A nitric oxide (NO) synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME, 50 microg/kg per min) also potentiated the endothelin-1-induced reductions in urine flow rate and urinary Na+ excretion but not the reduction in renal blood flow. Endothelin-1 reduced fractional Na+ excretion in the presence of BQ-788 or L-NAME. A spontaneous NO donor 1-hydroxy-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (30 ng/kg per min) slightly attenuated the antinatriuresis but not the vasoconstriction induced by endothelin-1. These results suggest that in the rabbit kidney in vivo endothelin ET(A) receptors mediate endothelin-1-evoked vasoconstriction and tubular Na+ reabsorption, that the concomitant stimulation of endothelin ET(B) receptors by endothelin-1 counteracts both the ET(A) receptor-mediated vascular and tubular actions, and that the tubular action, but not the vascular action, of endothelin-1 is also susceptible to changes in renal NO level.     

The effect of static electric and magnetic fields on the optical properties of amorphous hydrogenated silicon films produced by r.f. glow discharge

The aim of the present work was to study the optical properties of amorphous hydrogenated silicon films produced by capacitive and inductive r.f. glow discharge in a 3%SiH₄-Ar gas mixture. The effect of the application of static electric and magnetic fields during the film formation on the photoconductivity, photoactivation energy, recombination mechanisms and optical gap was thoroughly investigated. Films prepared in a capacitively or inductively coupled discharge show bias-dependent photoconductivities, which reach about 10^-4 Ω^-1 cm^-1 for an inductive discharge with a negative bias and about 10^-5 Ω^-1 cm^-1 for a capacitive discharge with a positive bias. The optical gap is of the order of 1.55 eV for capacitive films and is bias dependent for inductive films (1.45–1.85 eV). A superimposed magnetic field (of about 1 kG) increases the photoconductivity by one order of magnitude for both deposition methods. The optical gap is field dependent for inductive films (1.6–1.8 eV) and is about 1.6 eV for capacitive films. The main recombination mechanism at a moderate photon flux (less than 10¹⁴ cm^-2 s^-1) is monomolecular for all deposition conditions. The photoactivation energy lies between 0.1 and 0.2 eV for capacitive films and is about 0.1 eV for inductive films. It was also found that, by using suitable crossed electric and magnetic fields, it was possible to control the density and nature of the defect states in the films. These are correlated with the type of hydrogenated silicon species and with the amount of hydrogen incorporated into the films, which markedly influence the film properties.     

Gas absorption with autocatalytic reaction

The film theory has been employed to investigate gas absorption accompanied by an autocatalytic chemical reaction of the form A + ? → ? + ?. This reaction has been taken to be the simplest analogue of the autocatalytic features of chain reactions encountered in the industrially important gas-liquid oxidation and chlorination reactions. Numerical solutions have been obtained using standard library subroutines for integrating systems of first order equations, having transformed the two describing second order non-linear differential equations into suitable first order initial value form. Predictions of the Enhancement Factor show that it can be very considerably larger than that for the ‘equivalent’ first order reaction. This is due to the accumulation of radicals within the mass transfer film. An asymptotically exact empirical approximation for the Enhancement Factor is also presented. The ‘degree of conversion’ of the absorbed gas across the mass transfer film is shown to be more sensitive to the kinetic and diffusional parameters than is the case for a first order reaction.