NASTRAN as a resource in code development

A case history is presented in which the NASTRAN system provided both guidelines and working software for use in the development of a discrete element program, PATCHES-111. To avoid duplication and to take advantage of the wide spread user familiarity with NASTRAN, the PATCHES-111 system uses NASTRAN bulk data syntax, NASTRAN matrix utilities, and the NASTRAN linkage editor. Problems in developing the program are discussed along with details on the architecture of the PATCHES-111 parametric cubic modeling system. The system includes model construction procedures, checkpoint/restart strategies, and other features

Multilayer electret activated by direct contact silicon electrode.

Electrets used in microelectromechanical systems (MEMS) devices are often formed by corona charging, where ionized gases are generated in an electric field to introduce a charge to the electret surface. The purpose of this study was to investigate a new technique for creating an electret from a plasma enhanced chemical vapor deposition (PECVD) multilayer film of SiO2/Si3N4/SiO2 using a direct contact electrode of silicon. The electret formation takes advantage of deep traps in silicon nitride, which are known to develop from hydrogen interactions with silicon dangling bonds and, in some stoichiometries, nitrogen dangling bonds. The electret activation process has been optimized for maximum effective surface voltage (ESV). The deposition and activation process for the electret has the additional benefit of using commercially available equipment present in many microelectronic fabrication facilities. Standardized processes for depositing the PECVD film stack and activating the electret with a wafer level bonder have been developed.Using this new process, electret films have been produced with positive and negative effective surface voltages in excess of +/‐194.0 V. Extrapolated lifetimes, based on thermal decay studies, are calculated to be 57 years and 23 years for positive and negative electrets respectively if they are maintained in moderate to low humidity environments below 125°C. Activation energy levels in positive and negative electrets are 1.4 eV and 1.2 eV respectively. This new electret multilayer film stack and direct charging method produced thin film electrets with a half‐life 5 times greater than that reported in literature by other groups using PECVD multilayer electrets [1, 2]. A new application was investigated to see how an electret may benefit semiconductor‐liquid interactions. The PECVD electret was used to apply a gate bias to the back side of a double side polished silicon wafer to determine the effect of gate bias on the etch rates of an anisotropic silicon etch in 25% wt. tetramethylammonium hydroxide (TMAH). Our results show that the positively charged electret produced a statistically significant increase in etch rate, when compared to neutral and negatively charged electrets, as the silicon‐TMAH interface approached the depletion region produced by the electret. The mean values of the silicon etch rate were evaluated for the last hour of etching with samples categorized by electret potentials as positive, negative or neutral. The positive potential electret had a mean etch rate of 12.0 um/hr for silicon as compared to 8.8 um/hr and 8.6 um/hr for negatively and neutrally charge electrets respectively. The one way Analysis Of Variance (ANOVA) of the silicon etch rates between the neutral (control) PECVD film and the positive electret had a P value of 0.009 and falls within the 1% significance level, showing that it is very likely that the positive electret film has an effect on the final etch rate of the silicon under null hypothesis testing

Fiddler Crabs (Uca pugilator) as Bioindicators of Environmental Health in Coastal Estuarine Communities of Beaufort, South Carolina

Historically, coastal environmental health primarily has been analyzed through direct measurements of water, sediment, and contaminant residues in animal tissue. However, there is much evidence that certain species may serve as bioindicators, the ecological and morphological properties of which can predict the level of anthropogenic impact. The purpose of this study was to test the feasibility of utilizing the sand fiddler crab Uca pugilator as a bioindicator of anthropogenic impact. Three 30 m sq. sites (each divided into three subsites) were selected in Beaufort, South Carolina, as examples of different types and levels of human impact (a relatively unimpacted reference site, a municipal site receiving sewage effluent, and a golf course site receiving fertilizer and pesticides). Crabs (n = 1164) were assessed for carapace width, dominant to subordinate claw ratio (males only), and population density. Mating behavior was also observed. Carapace width was significantly reduced in the golf course crabs (p \u3c 0.001), and population densities were significantly greater at both affected sites compared to the reference site (p \u3c 0.001). Claw size ratios were significantly influenced by site, day, and the interaction of site and day (p = 0.005, 0.008, and 0.002 respectively), but there was no clear pattern in these influences. Reproductive behavior was increased in crabs at the golf course site. Due to limitations, this study suffers from pseudoreplication. However, this study demonstrates economical, noninvasive approaches to evaluate estuarine wellbeing

Cellular solid behaviour of liquid crystal colloids. 1. Phase separation and morphology

We study the phase ordering colloids suspended in a thermotropic nematic liquid crystal below the clearing point Tni and the resulting aggregated structure. Small (150nm) PMMA particles are dispersed in a classical liquid crystal matrix, 5CB or MBBA. With the help of confocal microscopy we show that small colloid particles densely aggregate on thin interfaces surrounding large volumes of clean nematic liquid, thus forming an open cellular structure, with the characteristic size of 10-100 micron inversely proportional to the colloid concentration. A simple theoretical model, based on the Landau mean-field treatment, is developed to describe the continuous phase separation and the mechanism of cellular structure formation.Comment: Latex 2e (EPJ style) EPS figures included (poor quality to comply with space limitations

Clinical review: The role of biomarkers in the diagnosis and management of community-acquired pneumonia

In patients with community-acquired pneumonia, traditional criteria of infection based on clinical signs and symptoms, clinical scoring systems, and general inflammatory indicators (for example, leukocytosis, fever, C-reactive protein and blood cultures) are often of limited clinical value and remain an unreliable guide to etiology, optimal therapy and prognosis. Procalcitonin is superior to other commonly used markers in its specificity for bacterial infection (allowing alternative diagnoses to be excluded), as an indicator of disease severity and risk of death, and mainly as a guide to the necessity for antibiotic therapy. It can therefore be viewed as a diagnostic, prognostic, and perhaps even theragnostic test. It more closely matches the criteria for usefulness than other candidate biomarkers such as C-reactive protein, which is rather a nonspecific marker of acute phase inflammation, and proinflammatory cytokines such as plasma IL-6 levels that are highly variable, cumbersome to measure, and lack specificity for systemic infection. Elevated levels of pro-adrenomedullin, copeptin (which is produced in equimolar amounts to vasopressin), natriuretic peptides and cortisol are significantly related to mortality in community-acquired pneumonia, as are other prohormones such as pro-atrial natriuretic peptide, coagulation markers, and other combinations of inflammatory cytokine profiles. However, all biomarkers have weaknesses as well as strengths. None should be used on its own; and none is anything more than an aid in the exercise of clinical judgment based upon a synthesis of available clinical, physiologic and laboratory features in each patient

Grain Boundary Loops in Graphene

Topological defects can affect the physical properties of graphene in unexpected ways. Harnessing their influence may lead to enhanced control of both material strength and electrical properties. Here we present a new class of topological defects in graphene composed of a rotating sequence of dislocations that close on themselves, forming grain boundary loops that either conserve the number of atoms in the hexagonal lattice or accommodate vacancy/interstitial reconstruction, while leaving no unsatisfied bonds. One grain boundary loop is observed as a "flower" pattern in scanning tunneling microscopy (STM) studies of epitaxial graphene grown on SiC(0001). We show that the flower defect has the lowest energy per dislocation core of any known topological defect in graphene, providing a natural explanation for its growth via the coalescence of mobile dislocations.Comment: 23 pages, 7 figures. Revised title; expanded; updated reference

The Effects of Price Regulation on Pharmaceutical R&D and Innovation

As rising health care expenditures focus government attention on slowing the growth, the pharmaceutical industry comes under increasing pressure to curb prices of ethical drugs. Pharmaceutical price regulations have been implemented in many countries to control pharmaceutical expenditures. Yet, creating innovative drugs requires enormous R&D costs, which in turn require adequate expected economic returns. Since price controls reduce profits and expected returns, as countries invoke stricter price regulations, firms will either move their R&D process into less regulated markets or move out of innovative R&D. This paper assesses the impact of drug price regulations in Japan compared to market-priced drugs in the US on pharmaceutical innovation

Exploring the Effects of Aromatic Molecules in Chemical Enhanced Oil Recovery

Chemical enhanced oil recovery (cEOR) methods are being used as a viable contributor to the world’s growing energy demands. Due to the complex chemical composition of crude oil, attempting to optimize the surfactant concentration and salinity of formulations is done empirically. This process can be very time intensive due to the wide variety of surfactant structures available for cEOR. Surfactant selection is typically done by matching the average chain length of the oil with that of the surfactant. In this study, we are trying to understand how aromatic structures present in Illinois Basin crude oil interact with surfactants. This will potentially help guide the process of surfactant selection. For this experiment, we used three model oils: dodecane, dodecane + 10% toluene, and dodecane + 35% toluene. We performed phase behavior testing with two anionic surfactants at a variety of salinities with the model oils. One surfactant is an alkyl propoxy sulfate and the other is alkyl benzene sulfonate. Measurement of the interfacial tension (IFT) between the oil and surfactant dissolved in an aqueous solution provides a quantitative measure of how efficiently the surfactant interacts with the oil. The lower the IFT, the more effective the surfactant. So far, we have observed significant differences in the micro emulsions when the model oil contains aromatics. The results suggest that surfactants containing aromatics play an important role in interacting with the aromatic groups present in the oil. It is anticipated that these results will provide mechanistic insight about the contribution of aromatic structures in surfactant selection