Liquid–liquid equilibria of the ternary system water + acetic acid + dimethyl adipate

Liquid–liquid equilibrium (LLE) data of water + acetic acid + dimethyl adipate have been determined experimentally at 298.15, 308.15 and 318.15 K. Complete phase diagrams were obtained by determining binodal curve and tie-lines. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. UNIFAC and modified UNIFAC models were used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data of CH₂, CH₃COO, CH₃, COOH, and H₂O functional groups. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

Viscosities, Apparent Molar Volumes, Expansivities and Isentropic Compressibilities of some Fatty Acids and their Triglycerides in Benzene at (20, 30, 40 and 60) °C

Viscosities, apparent molal volumes, compressibilities and expansivities of lauric, palmitic and stearic acids and their triglycerides, trilaurin, tripalmitin and tristearin, were determined in benzene at 20, 30, 40 and 60 °C. Accurate density and sound velocity measurements carried out simultaneously with a high-precision vibrating-tube densimeter and sound velocity measuring device were utilized in deriving volume, compressibility and expansivity data. Viscosities were measured with Ostwald type viscometers. Infinite dilution values of the apparent molal volumes and compressibilities were obtained by an extrapolation procedure. Apparent molal expansivities at infinite dilution were obtained from the temperature dependence of the apparent molar volume at infinite dilution. The properties at infinite dilution were evaluated in terms of solute-solvent interactions. Volumetric results in benzene were compared with the corresponding data estimated from group contributions in aqueous solutions using the additivity rule.     

Spatial unmasking of birdsong in human listeners: energetic and informational factors

Spatial unmasking describes the improvement in the detection or identification of a target sound afforded by separating it spatially from simultaneous masking sounds. This effect has been studied extensively for speech intelligibility in the presence of interfering sounds. In the current study, listeners identified zebra finch song, which shares many acoustic properties with speech but lacks semantic and linguistic content. Three maskers with the same long-term spectral content but different short-term statistics were used: (1) chorus (combinations of unfamiliar zebra finch songs), (2) song-shaped noise (broadband noise with the average spectrum of chorus), and (3) chorus-modulated noise (song-shaped noise multiplied by the broadband envelope from a chorus masker). The amount of masking and spatial unmasking depended on the masker and there was evidence of release from both energetic and informational masking. Spatial unmasking was greatest for the statistically similar chorus masker. For the two noise maskers, there was less spatial unmasking and it was wholly accounted for by the relative target and masker levels at the acoustically better ear. The results share many features with analogous results using speech targets, suggesting that spatial separation aids in the segregation of complex natural sounds through mechanisms that are not specific to speech.     

Carotenoids and Related Compounds. Part 36.. Further syntheses of zeaxanthin and rhodoxanthin

A modification of a previously reported synthesis of zeaxanthin ( 1 ), and routes to both zeaxanthin and rhodoxanthin ( 2 ) from α-ionone, are described.     

Flow equivalence and stochastic equivalence in G-networks

G-networks are novel product form queuing networks that, in addition to ordinary customers, contain unusual entities such as negative customers which eliminate normal customers, and triggers that move other customers from some queue to another. Recently we introduced one more special type of customer, a reset, which may be sent out by any server at the end of a service epoch, and that will reset the queue to which it arrives into its steady state when that queue is empty. A reset which arrives to a non-empty queue has no effect at all. The sample paths of a system with resets is significantly different from that of a system without resets, because the arrival of a reset to an empty queue will provoke a finite positive jump in queue length which may be arbitrarily large, while without resets positive jumps are only of size + 1 and they occur only when a positive customer arrives to a queue. In this paper we review this novel model, and then discuss its traffic equations. We introduce the concept of stationary equivalence for queueing models, and of flow equivalence for distinct queueing models. We show that the flow equivalence of two G-networks implies that they are also stationary equivalent. We then show that the stationary probability distribution of a G-network with resets is identical to that of a G-network without resets whose transition probabilities for positive (ordinary) customers has been increased in a specific manner. Our results show that a G-network with resets has the same form of traffic equations and the same joint stationary probability distribution of queue length as that of a G-network without resets.     

Observation of an x-ray vortex

Phase singularities are a ubiquitous feature of waves of all forms and represent a fundamental aspect of wave topology. An optical vortex phase singularity occurs when there is a spiral phase ramp about a point phase singularity. We report an experimental observation of an optical vortex in a field consisting of 9-keV x-ray photons. The vortex is created with an x-ray optical structure that imparts a spiral phase distribution to the incident wave field and is observed by use of diffraction about a wire to create a division-of-wave-front interferometer.     

On the eigenvalues of a 3 by 3 non-Hermitian Hamiltonian

In this paper, we are concerned with a 3 × 3 complex matrix Jacobi (tri-diagonal matrix) arised from a non-Hermitian discrete quantum system. Necessary and sufficient conditions for reality of the eigenvalues of the matrix in question are established.     

Electrokinetic and electrorheological properties of poly(vinyl chloride)/polyindole conducting composites

In this study, poly(vinyl chloride) (PVC), polyindole (PIN), and PVC/PIN conducting composites having five different compositions were used. Particle sizes, densities, dielectric constants, and sedimentation ratios of the materials were determined. The zeta‐potentials of the samples were measured in aqueous and nonaqueous (silicone oil [SO]) media. The dispersions prepared in SO were subjected to external electric field strength, and their electrorheological properties were investigated. Then the effects of dispersed particle volume fraction, shear rate, external electric field strength, frequency, and temperature onto electrorheological activities of the dispersions were examined. Further, creep and creep‐recovery tests were applied to the PIN/SO and PVC/PIN/SO dispersions, and reversible viscoelastic deformations were observed. Finally, the vibration damping capacity of PVC (66%)/PIN (34%)/SO dispersion system was tested by using an automobile shock absorber. Copyright © 2011 John Wiley & Sons, Ltd.