TRANSPORT PROPERTIES AND SECOND VIRIAL COEFFICIENTS FOR XENON

An accurate potential of The Hartree-Fock Dispersion (HFD) form for xenon was constructed (Dham, Meath, Allnatt, Aziz and Slaman, 1990) by a multiproperty fit to several sets of experimental data. Along with the data to which it was fitted, the potential accurately reproduces a wide range ofother bulk and microscopic data, and appears to be the best available characterization of the xenon interaction. Based on this potential, second virial coefficients and transport properties of dilute xenon gas are tabulated from 100 to 6,200 K, and empirical functions are presented for interpolating between the tabulated values.     

Flame development characteristics at variable swirl level inductions in a stratified CNG direct injection combustion engine

The study of flame development characteristics is crucial in the study of flame propagation, extinction, and for the investigation of combustion cyclic variability in SI engine. The aim of this study is to investigate the characteristics of flame development in a lean-stratified combustion of Natural Gas Engine （CNG） in a single cylinder direct injection （DI） engine at a specific motor speed, and fixed injection timing and air-fuel ratio by varying only the swirl level at the intake. The engine was set to run at 1800 rpm with half-load throttled. The ignition advance was set at 21.5 BTDC, and to create an overall lean and stratified mixture, injection timing was set at 61 BTDC with an air-fuel-ratio of 40.5 （λ=2.35）. Variable turbulent flow conditions near spark-plug were created by positioning the swirl control valves （SCV） at the intake port just before the two intake valves. This was done by setting one of the valves at full open position and the other one at 0% closed, 50% closed and 100% closed positions in order to achieve medium tumble （no swirl）, medium swirl and high swirl flows in the cylinder, respectively. An endoscope and CCD camera assembly was utilized to capture the flame images from the tumble plane at the intake side of the engine ever）, 2 CA degrees after ignition timing （AIT） for 40 CAs. It was observed that flame growth rate and flame convection velocity are increasing with increasing the swirl level. The total combustion duration is, thus, shorter in swirl induced combustion than without. However, COV in IMEP is greater in swirl induced flow cases than the medium tumble.     

Copolymerization of elemental sulfur with styrene

Copolymerization of elemental sulfur with styrene in the presence and absence of metallic sodium was studied at 120°C and 138°C. Propagation of the reaction was followed by gel permeation chromatography (GPC). Glass transition temperatures of all samples were obtained by differential scanning calorimetry (DSC). Reaction products were fractionated with a preparative-type GPC, and each fraction was characterized by DSC, vapor pressure osmometry, infrared spectrophotometry, and both proton and carbon-13 nuclear magnetic resonance spectrometry. Results indicate that the product is a true copolymer of styrene and sulfur. Kinetics of the copolymerization were studied using GPC to monitor styrene and sulfur concentrations. The initial rate of copolymerization (as followed by the consumption of styrene and sulfur) decreases with increasing initial styrene to sulfur ratio. From kinetic analyses, ratios of the rate constants of homo- and copolymerization were determined. Copolymerization of the reactants is more spontaneous than homopolymerization. The reactivity ratios obtained are 0.2 for styrene and 0.6 for sulfur.     

Salmonellosis in Indonesia: phage type distribution of Salmonella typhi

The distribution of phage types was studied among 577 strains of Salmonella typhi from Indonesia. Chemotype, colicinogeny, and tetrathionate reductase activity were also studied for most of these strains. The current phage type formula for Java was determined to be: A, D2, D6, E1a, E2, M1, and 46, but two other large groups of strains were also found, I + IV and degraded Vi+ strains. Significant differences in S. typhi strain distributions were noted between two localities on Java with respect to phage type and tetrathionate reductase activity. Comparisons were made with past phage typing studies in Jakarta as well as with more recent studies in other parts of south-east Asia. Phage types A, D1, D2, and E1 persisted at a rather steady level in Jakarta for 28 years. Evidence was found for epidemiological links to European and Asian areas. Antibiotic resistance among these Indonesian S. typhi strains was rare.     

Synthesis,characterization of phosphine oxide-containing polyimides and their use as selective membrane for dopamine

Tris-(p-aminophenoxy)phosphineoxide, t-APPO, was prepared from 4-nitrophenol and POCl₃, followed by hydrogenation. A series of polyimides prepared from t-APPO and the corresponding dianhydrides by two-stage polycondensation method was characterized by Fourier Transform Infrared Spectrometer (FTIR), GPC, thermal analysis and physical methods. Moreover, in order to check the permeation properties of the resulting polyimide film, the selectivity of the polyimide-coated electrode toward electroactive species (ascorbic acid and dopamine) was examined by means of cyclic voltammetry (CV), differential pulse voltammetry (DPV) and time-base amperometric measurement (TB) techniques. As a result, it has been found that polyimide electrode showed selective permeation for dopamine while blocking the permeation of ascorbic acid through film. Therefore, it has been claimed that phosphine oxide-containing polyimide electrode can be used as a dopamine-selective membrane in the presence of ascorbic acid.     

Delayed positive thallium uptake in large B-cell non-Hodgkin's malignant lymphoma

We report an unusual finding in an AIDS patient who presented with a large mediastinal mass and multiple lymphadenopathy. A sequential thallium and gallium scan to specify the nature of the mediastinal mass was requested. The early thallium images, acquired 15 min after the intravenous injection, showed no uptake in the mass. The delayed images 2 hr later showed intense thallium uptake. A gallium scan performed 48 hr later also showed intense gallium uptake in the mediastinal mass. Biopsy from the inguinal lymph node confirmed the presence of large-cell diffuse noncleaved malignant lymphoma. This case raises questions about the optimum time of imaging for thallium in high-grade lymphoma, whether delayed imaging is essential, about previous reports of low sensitivity of thallium in undifferentiated lymphoma and about the mechanism of thallium uptake in this type of tumor.     

Dielectric and ultrasonic absorption in some linear polyamides

The dielectric behavior of some linear polyamides has been studied over a frequency range from 10² to 10⁵ Hz between 20°C and 90°C. Also the change in attenuation of longitudinal ultrasonic waves has been measured as a function of frequency and temperature. Analysis of the results shows α- and β- relaxations. The movement of amide protons involved in intermolecular hydrogen bonds is also noticed.     

Analytical and numerical modeling of steady periodic heat transfer in extended surfaces

This paper deals with the analytical and numerical approaches that have been used to study periodic or oscillatory heat transfer processes occurring in extended surfaces. The details pertain to harmonic oscillations but many of the methods can be applied to more general periodic functions. For linear problems, the techniques include complex combination, Laplace transforms, finite differences, and boundary elements. For the nonlinear situations, approaches such as finite differences, finite elments, and different combinations of complex temperature, perturbation, series expansions, straightline, and finite differences have proved effective. Following a brief introduction, the applications of each approach are discussed in detail. Both straight and annular fin configurations are covered and the profile shapes include rectangular, trapezoidal, triangular, and convex parabolic. The periodic conditions involve oscillating base temperature, oscillating base heat flux, oscillating environment temperature, convection at the fin's base through a fluid with oscillating temperature, and some combinations of these conditions. The nonlinear problems discussed cover radiating and convecting-radiating fins, fins with variable thermal conductivity and coordinate dependent heat transfer coefficients, and systems with fin-to-fin, fin-to-base, and fin-to-environment radiative interactionsThis article is dedicated to the memory of first author's younger brother, Mohammed Iqbal, Civil Services of Pakistan, who became an innocent victim of human savagery in 1971 in what was then East Pakistan     

Geometric modeling of the human normal cerebral arterial system

We propose an anatomy-based approach for an efficient construction of a three-dimensional human normal cerebral arterial model from segmented and skeletonized angiographic data. The centerline-based model is used for an accurate angiographic data representation. A vascular tree is represented by tubular segments and bifurcations whose construction takes into account vascular anatomy. A bifurcation is defined quantitatively and the algorithm calculating it is given. The centerline is smoothed by means of a sliding average filter. As the vessel radius is sensitive to quality of data as well as accuracy of segmentation and skeletonization, radius outlier removal and radius regression algorithms are formulated and applied. In this way, the approach compensates for some inaccuracies introduced during segmentation and skeletonization. To create the frame of vasculature, we use two different topologies: tubular and B-subdivision based. We also propose a technique to prevent vessel twisting. The analysis of the vascular model is done on a variety of data containing 258 vascular segments and 131 bifurcations. Our approach gives acceptable results from anatomical, topological and geometrical standpoints as well as provides fast visualization and manipulation of the model. The approach is applicable for building a reference cerebrovascular atlas, developing applications for simulation and planning of interventional radiology procedures and vascular surgery, and in education.