Evaluation of standard and real fire exposures on thermal response of rail car floor assembly

This work developed a computational methodology to evaluate and compare standard fire exposures such as those outlined in ASTM E119 with real fire exposures and determine the difference in the temperature rise of a rail car floor assembly. The real fire exposures simulated in this work were identified in a review of incidents and consisted of a constantly-fed diesel fuel spill, a localized trash fire, and a gasoline spill simulated from a collision of the railcar with an automobile. These realistic fire exposures were applied to a variety of exemplar rail cars representative of single-level and bi-level passenger cars. These floor assembly models exposed to realistic fires were simulated in Fire Dynamics Simulator (FDS). The thermal exposure at the underside of railcar provided by FDS was coupled with a thermal model in ABAQUS, which provided the evolution of temperature in different components of the floor assembly. The standard scenarios were simulated for 2 hours instead of the typical 30 minutes to identify the appropriate exposure duration in ASTM E119, which can better represent a real fire scenario. The average and maximum temperatures predicted at the unexposed surface for both scenarios were compared with the threshold values given in NFPA 130.     

Contributions of Metaknowledge to Retrieval of Natural Categories in Semantic Memory.

Retrieving the answer to a general knowledge question has been shown to involve two metacognitive processes--a feeling-of-knowing that initiates the search of long-term memory and a willingness to continue searching until an answer can be confidently stated. To extend this model, college students were asked to retrieve as many members of 2 natural categories as they could in 1 min. Examination of the points at which they switched categories revealed that they searched longer in categories of higher potency, and they switched earlier when the other category was of higher potency. They also searched the first category longer when they were allowed to switch only once during a trial rather than as often as they wished. It was concluded that feeling-of-knowing maintained search of a category and also contributed to the willingness to continue searching, and the constraint on switching impacted the willingness to continue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An investigation of carbon nanotube jet grinding

Since their observation in 1976 and 1991, carbon nanotubes (CNTs) have generated much interest due to their properties and potential applications. CNTs are tubular carbon molecules with remarkable mechanical, electrical, chemical and thermal properties, which make them useful in various applications. Industries producing CNTs via the fluidized bed chemical vapor deposition technique face challenges related to the size of CNT bundles. The two main challenges are agglomeration and agglomerate size distribution control. A solution to these challenges involves the use of jet mills to grind the CNT agglomerates. The goal of this study was to determine whether the nanotubes could be ground with air jets using a commercial jet mill and apply a two-parameter model to describe the grinding process. The present study has indicated that air-jet grinding of CNTs is feasible with a typical commercial jet mill. This paper presents the effect of operational parameters on the arithmetic mean diameter of the ground product. Sonic velocity through the grinding nozzles was required to obtain reasonable grinding rates and relatively narrow particle size distributions. This occurs at high air to solids feedrate ratios. Additionally, a simple attrition model can describe the grinding process in the spiral jet mill.     

Longitudinal analysis of the relationship between symptoms and quality of life in veterans treated for posttraumatic stress disorder.

This study examined how change in posttraumatic stress disorder (PTSD) symptoms relates to change in quality of life. The sample consisted of 325 male Vietnam veterans with chronic PTSD who participated in a randomized trial of group psychotherapy. Latent growth modeling was used to test for synchronous effects of PTSD symptom change on psychosocial and physical health-related quality of life within the same time period and lagged effects of initial PTSD symptom change on later change in quality of life. PTSD symptoms were associated with reduced quality of life before treatment. There were synchronous effects of symptom change on change in quality of life but no significant lagged effects. Results indicate the importance of measuring quality of life in future investigations of PTSD treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Project Preserve: A Program to Retain Minorities in Engineering

A national effort, begun in 1972 to increase the numbers of minorities in engineering, has made substantial progress, but the attrition for minority students is still estimated at 70%. To address the problem, Project Preserve was designed to confirm, by demonstration, the results of previous research showing that the combination of explicit cognitive development, close relationships with faculty, and strong bonds to an institution can raise the performance and retention of minority engineering students. The project enrolled over 100 minority engineering students who had been dismissed from freshman engineering studies on other campuses or placed on academic probation, but whose high school grades and SAT scores were indicative of success. They were channeled into participating institutions chosen for their record of basic support services, willingness to augment or restructure those services, and for variation among institutional variables: Xavier University of Louisiana (XU), California State University at Northridge (CSUN), and City College of the City University of New York (CCNY). A 2 1/2 hour battery of evaluation instruments was given to 79 students upon entry and to 26 students upon their attaining Junior status after two years in the program. The results demonstrated that: (1) an admirable 64% of would-be drop outs had achieved Junior status or were still enrolled in engineering at the conclusion of two years; (2) cognitive growth occurred on basic memory skills and one critical thinking skill, but there were institutional differences in the extent of intellectual development, with Xavier producing the most change; (3) closer relationships to faculty were outcomes; (4) the most positive feelings about, or bonding to, the institution occurred at Xavier University, while the most evidence of social participation and connectedness occurred at CSUN.     

PGRP-LB: An Inside View into the Mechanism of the Amidase Reaction

Peptidoglycan recognition proteins (PGRPs) are ubiquitous among animals and play pivotal functions in insect immunity. Non-catalytic PGRPs are involved in the activation of immune pathways by binding to the peptidoglycan (PGN), whereas amidase PGRPs are capable of cleaving the PGN into non-immunogenic compounds. Drosophila PGRP-LB belongs to the amidase PGRPs and downregulates the immune deficiency (IMD) pathway by cleaving meso-2,6-diaminopimelic (meso-DAP or DAP)-type PGN. While the recognition process is well analyzed for the non-catalytic PGRPs, little is known about the enzymatic mechanism for the amidase PGRPs, despite their essential function in immune homeostasis. Here, we analyzed the specific activity of different isoforms of Drosophila PGRP-LB towards various PGN substrates to understand their specificity and role in Drosophila immunity. We show that these isoforms have similar activity towards the different compounds. To analyze the mechanism of the amidase activity, we performed site directed mutagenesis and solved the X-ray structures of wild-type Drosophila PGRP-LB and its mutants, with one of these structures presenting a protein complexed with the tracheal cytotoxin (TCT), a muropeptide derived from the PGN. Only the Y78F mutation abolished the PGN cleavage while other mutations reduced the activity solely. Together, our findings suggest the dynamic role of the residue Y78 in the amidase mechanism by nucleophilic attack through a water molecule to the carbonyl group of the amide function destabilized by Zn²⁺.     

Thermal stability of NO 2 ⋅ and NO⋅ radicals formed in an Al23 catalyst during its preparation from a nitrate precursor

During the preparation of alumina as a catalyst support from aluminium nitrates by precipitation with a NH₄OH base, NO ₂ ^⋅ radicals have been formed in the catalyst after calcination under air in the solid at different temperatures. These radicals remained stable until a calcination temperature of 800°C. When the calcined catalyst was degassed under vacuum above 300 °C, the NO ₂ ^⋅ was reduced to give NO^⋅ and O^- species which were both tightly trapped in the solid. These latter species remained stable until vacuum treatment at 800 °C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cross-Campus Collaboration to Produce Camtasia-Enhanced Lessons to Improve Distance Learning

This pilot study examines the use of Camtasia-enhanced lessons to supplement distance education provided to medical laboratory science students. More programs of study are available as distance learning opportunities, creating challenges to find better ways to present material. Librarians provided technical expertise necessary to produce a Camtasia video. This helped instructors prepare engaging lectures for phlebotomy to supplement the PowerPoint presentations and self-directed lessons provided in previous courses. Medical laboratory science faculty collaborated with library staff to produce videos that demonstrate proper phlebotomy technique using training personnel and faculty, whom the students eventually interact with in the clinical environment.