Estimation of particle volume fraction, mass fraction and number density in thermophoretic deposition systems

A method is presented to predict the soot volume fraction in soot-laden gas streams in systems where thermophoresis is the dominant mechanism of particle deposition onto adjoining surfaces. In particular, we considered deposition of silica particles on a circular cylinder in cross-flow to a premix CH₄/O₂ flame, a setup similar to the one used in the outside vapor deposition process used for making optical fibers. Silica particles were produced by introducing SiCl₄ along with the premix gases to the burner and were collected on a cylinder. Heat flux and mass deposition rate measurements on the cylinder were performed and recorded as a function of time. Considering thermophoresis to be the dominant mechanism of particle deposition, a simple theory was developed to establish the relationship between the measured quantities. The theory predicted that the thickness at any given time t was expected to increase linearly with the integral of (integrated from t=0 to t=t), where q^′′(t) is the heat flux. Such a linear relationship was observed for five different reactant flow rates confirming thermophoresis to be the dominant mechanism of particle deposition. Soot volume fraction and soot mass fraction were calculated from the slope of these linear fits and were seen to be in good agreement with the estimates of the soot fraction from light scattering measurements. Based on the light scattering estimates of particle diameter, particle number densities were also estimated.     

New synchronisation method for satellite-switched time-division multiple-access systems

A new synchronisation method for satellite-switched time-division multiple-access systems is described. It is shown that this method has some significant system benefits, and involves a small increase in satellite hardware complexity.     

Fatigue life response of ASME SA 106-B steel in pressurized water reactor environments

Fatigue strain-life tests were conducted on ASME SA 106-B piping steel base metal and weld metal specimens in 288°C (550°F) pressurized water reactor (PWR) environments as a function of strain amplitude, strain ratio, notch acuity, and cyclic frequency. Notched base metal specimens tested at 0·017 Hz in 0·001 part per million (ppm) dissolved oxygen environments nearly completely used up the margins of safety of 2 on stress and 20 on cycles incorporated into the ASME Section III design curve for carbon steels. Tests conducted with smooth base metal and weld metal specimens at 1·0 Hz showed virtually no degradation in cycles to failure when compared to 288°C air test results. In all cases, however, the effect of temperature alone reduced the margin of safety offered by the design curve in the low cycle regime for the test specimens. Comparison between the fatigue life results of smooth and notched specimens suggests that fatigue crack initiation is not significantly affected by 0·001 ppm dissolved oxygen, and that most of the observed degradation may be attributed to crack growth acceleration. These results suggest that the ASME Section III methodology should be reviewed, taking into account the PWR environment variables which degrade fatigue life of pressure-retaining components.     

Observability of nonlinear differential algebraic systems

We define the smooth observability of nonlinear DAE systems and give sufficient conditions for this property to hold locally in a neighborhood of a solution. The matrix rank conditions for observability are verifiable by a combination of symbolic and numerical linear algebra computations. These conditions generalize conditions that have appeared in the literature for observability of linear time-varying DAE systems. We indicate how the main result is potentially useful in studying a system's zero dynamics. Some relevant rank properties of Hessenberg DAE systems are established.This work was supported in part by the Grant-In-Aid Program for Faculty of Virginia Commonwealth University.     

22-Mb integrated physical and genetic map based on YAC/STS content spanning the interval DXS1125-DXS95 in human Xq12-q21.31

Wild-type p53 (wt-p53), a key protein in cell cycle regulation, inactivates the G1 cyclins through direct activation of p21Waf-1/Cip-1/Sdi-1. Persistent vascular smooth muscle cell (VSMC) proliferation following vascular interventions hinders the benefits of these therapeutics. Using the hemagglutinating virus of Japan/liposome-mediated gene transfer method, we examined the inhibitory effect of overexpression of exogenous wt-p53 on VSMC proliferation in vitro and in vivo. We assessed the proliferative activity of human p53 cDNA-transduced bovine VSMCs by DNA synthesis assay, flow cytometry, and cell proliferation assay. p53 gene transfer reduced thymidine incorporation of VSMCs stimulated by platelet-derived growth factor-BB (P<.001). The p53-transduced VSMCs underwent synthetic phase depletion (mean, 8.02% versus 33.7% of control; P<.001) and transient G2/M accumulation 2 days after gene transfection, and in almost all cells, G1 arrest occurred (mean, 92.6% versus 79.3% of control; P<.001) 5 days later. The wt-p53 gene transfection also inhibited the VSMC proliferation (P<.001) with no detectable induction of apoptosis. Cell death of p53-transduced VSMCs was induced only by additional treatment with an apoptosis-stimulating reagent, doxorubicin. The verification of apoptosis was made by DNA ladder, flow cytometry, and electron microscopy. In vivo transfection of p53 cDNA inhibited neointimal formation after balloon injury in rabbit carotid arteries, without apoptotic stimuli (P<.01). Thus, overexpression of the p53 gene in the injured arterial wall inhibits the proliferation of VSMCs in vitro and in vivo. This novel concept, including not only exogenous but also endogenous p53 overexpression in the vessel wall, may be one approach worth exploring in the treatment of patients with restenosis occurring after vascular interventions.     

Depression and the illusion of control

24 depressed and 24 nondepressed undergraduates (Beck Depression Inventory) placed bets on a dice game. The throwing of the dice was either under player-control or croupier-control conditions. As predicted, depressed Ss were more confident of success in the croupier-control condition, and nondepressed Ss were more confident of success in the player-control condition. Results support the view that depressed Ss are characterized by a sense of personal incompetence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motivational and associative aspects of mild depression in skill and chance tasks.

In Exp I, the levels of aspiration and expectancies for success of 281 mildly depressed and nondepressed college students on a skill and chance task were studied. The 2 groups did not differ in expectations for success, but depressed Ss displayed elevated levels of aspiration, particularly for the skill task. Exp II, with 120 college students, tested the prediction, based on an attainment discrepancy model, that increases in expectancy for success would be a function of the interaction of performance level and the skill–chance nature of a task for mildly depressed Ss but not for nondepressed Ss. Comparisons of increases in expectancy for success following average and superior performance support this prediction. The prediction that locus of control (Rotter's Internal–External Locus of Control Scale) and depression (Beck Depression Inventory) would not be significantly correlated was also confirmed. Results indicate that the level of aspiration of mildly depressed persons may be particularly elevated in skill tasks, resulting in the perception of average performance in such tasks as unsuccessful. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antioxidant capacities,procyanidins and pigments in avocados of different strains and cultivars

Avocado (Persea americana) is an important tropical fruit, but little is known about their antioxidant capacities and phytochemical composition. The objective of this research was to determine antioxidant capacities, total phenolic content and identify and quantify major antioxidant compounds in avocados of different strains and cultivars. Ripe Florida avocados from seven cultivars (Slimcado, Booth 7, Booth 8, Choquette, Loretta, Simmonds, and Tonnage) of West Indian or Guatemalan strains were separated into seeds, peels and pulp, and freeze dried. Hass avocado of Mexican strain was chosen for comparison. Samples were extracted with acetone/water/acetic acid solvent and analysed using the Folin–Ciocalteu assay for total phenolic content. Antioxidant capacities were determined by oxygen radical absorbance capacity (ORAC) and DPPH assays. Procyanidins were identified and quantified using HPLC-MSⁿ. Antioxidant pigments (chlorophylls and carotenoids) were estimated spectrophotometrically. For all varieties, seeds contained the highest antioxidant capacities, phenolic content, and procyanidins, whereas the pulp had the lowest. Procyanidins, including catechin, epicatechin, A- and B-type dimers, A- and B-type trimers, tetramers, pentamers and hexamers, were identified in peels and seeds using normal-phase HPLC–ESI-MSⁿ. Antioxidant capacities, phenolic contents and procyanidins in avocados were highly correlated, suggesting that procyanidins were the major phenolic compounds that contributed to antioxidant capacities. Carotenoids and chlorophylls were found to be concentrated in avocado peels but did not correlate with antioxidant capacities. This study suggested that avocado seeds and peels, industrial wastes of avocado processing, can be exploited as source of antioxidants.     

Synthesis and Dielectric Properties of Subsituted Lanthanum Aluminate

LaAlO₃ was chemically modified in order to ascertain the effects of substitution of larger cations on the compound's slight rhombohedral distortion from cubic symmetry—a property that often degrades the performance of LaAlO₃ substrates for epitaxial high-temperature superconducting films. La_{1– x} Sr _x Al_{1– x} Ti_xO₃ (x = 0–05, 0.10, 0.15, 0.25),La_{1– x} Sr_xAl_1–xZr_xO₃, La_{1– x} Sr _x Al_1–xMg_xO_3–2xF _2x and La_{1– x} ,Sr_xAl_{1– x} Sc _x O_{3– x} (x = 0.05, 0.10, 0.15) were prepared in polycrystalline form and 1–2 mm single crystals of the Sr,Ti- and Sr,Zr-substituted systems were grown using a PbO–PbF₂–B₂O₃–PbO₂ flux. Shifts in the peak positions of the X-ray powder diffraction patterns confirmed subsitution of the larger cations. The diffraction patterns were also typified by the line-broadening and the decrease in the rhombohedral splitting at all doping levels. The dielectric constant of LaAlO₃ was unchanged for all of the fluoride-containing systems and for the 5% Sr, Ti- and Sr,Zr-systems.