Effects of upholstery materials on the burning behavior of real‐scale residential upholstered furniture mock‐ups

Fire spread and growth on real‐scale four cushion mock‐ups of residential upholstered furniture (RUF) were investigated with the goal of identifying whether changes in five classes of materials (barrier, flexible polyurethane foam, polyester fiber wrap, upholstery fabric, and sewing thread), referred to as factors, resulted in statistically significant changes in burning behavior. A fractional factorial experimental design plus practical considerations yielded a test matrix with 20 material combinations. Experiments were repeated a minimum of two times. Measurements included fire spread rates derived from video recordings and heat release rates (HRRs). A total of 13 experimental parameters (3 based on the videos and 10 on the HRR results), referred to as responses, characterized the measurements. Statistical analyses based on Main Effects Plots (main effects) and Block Plots (main effects and factor interactions) were used. The results showed that three of the factors resulted in statistically significant effects on varying numbers of the 13 responses. The Barrier and Fabric factors had the strongest main effects with roughly comparable magnitudes. Foam was statistically significant for fewer of the responses and its overall strength was weaker than for Barrier and Fabric. No statistically significant main effects were identified for Wrap or Thread. Multiple two‐term interactions between factors were identified as being statistically significant. The Barrier*Fabric interaction resulted in the highest number of and strongest statistically significant effects. The existence of two‐term interactions means that it will be necessary to consider their effects in approaches designed to predict the burning behavior of RUF.     

Oxidative degradation of polyamide reverse osmosis membranes: Studies of molecular model compounds and selected membranes

Selected aromatic amides were used to model the chemical reactivity of aromatic polyamides found in thin‐film composite reverse osmosis (RO) membranes. Chlorination and possible amide bond cleavage of aromatic amides upon exposure to aqueous chlorine, which can lead to membrane failure, were investigated. Correlations are made of the available chlorine concentration, pH, and exposure time with chemical changes in the model compounds. From the observed reactivity trends, insights are obtained into the mechanism of RO membrane performance loss upon chlorine exposure. Two chemical pathways for degradation are shown, one at constant pH and another that is pH‐history dependent. An alternative strategy is presented for the design of chlorine‐resistant RO membranes, and an initial performance study of RO membranes incorporating this strategy is reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1173–1184, 2003     

Explosive chemistry: Simulating the chemistry of energetic materials at extreme conditions

In this article, we review recent atomistic computational techniques to study the electronic structure aspects and chemistry of energetic materials at high-pressure and/or high temperature. While several mechanisms have been proposed for the initial events of energetic materials at high-pressure, we explore the validity of a proposed shear-induced local metallization via molecular bond bending in the insensitive explosive TATB. We study the effect of high-stress (both uniform and uniaxial) on the electronic energy band-gap and the first chemical event of a prototypical energetic material, that of nitromethane. We also determine chemical reactions rate laws and decomposition mechanisms from a quantum-based molecular dynamics simulation of HMX, a widely used explosive material, at conditions of high density and temperature similar to that encounter under detonation. Finally, we review a new multi-scale computational tool recently developed to model the shock-induced chemistry of energetic materials at the atomistic level, and report its applicability to shocked solid nitromethane. This revised version was published online in June 2006 with corrections to the Cover Date.     

Human alpha 2-macroglobulin is an osteogenic growth peptide-binding protein

The osteogenic growth peptide (OGP) is a 14mer mitogen of osteoblastic and fibroblastic cells. Physiologically, OGP is present in high abundance in human and other mammalian sera. Most of the serum OGP is complexed noncovalently to heat sensitive, high molecular weight OGP-binding proteins (OGPBPs). Changes in serum OGP levels that follow bone marrow ablation and the low doses of exogenous OGP required for the stimulation of bone formation suggest a regulatory role for the OGPBPs. In the present work, the OGP binding activity was monitored by competitive binding to [3-125I(Tyr10)]-sOGP and the corresponding complexes were demonstrated on nondenaturing cathodic polyacrylamide gel electrophoresis. We show that OGP binds to both native and activated human plasma alpha 2-macroglobulin (alpha 2M). alpha 2M was also immunoidentified in reduced and nonreduced SDS-polyacrylamide gel electrophoresis of OGP-affinity purified plasma-derived proteins. Immunoreactive OGP was detected in commercial preparations of both forms of alpha 2M; OGP was purified to homogeneity from the commercial preparation of activated alpha 2M. In MC3T3 E1 cells, native alpha 2M, at concentrations < 50 ng/mL, had a substantially increased mitogenic effect in the presence of synthetic, native-like, OGP (sOGP). Similar amounts of activated alpha 2M inhibited the sOGP proliferative effect. These results suggest that the native alpha 2M enhances the immediate availability of OGP to its target cells. Activated alpha 2M may participate in the removal of OGP from the system.     

Massively parallel algorithms for trace-driven cache simulations

Considers the use of massively parallel architectures to execute a trace-driven simulation of a single cache set. A method is presented for the least-recently-used (LRU) policy, which, regardless of the set size C, runs in time O(log N) using N processors on the EREW (exclusive read, exclusive write) parallel model. A simpler LRU simulation algorithm is given that runs in O(C log N) time using N/log N processors. We present timings of this algorithm's implementation on the MasPar MP-1, a machine with 16384 processors. A broad class of reference-based line replacement policies are considered, which includes LRU as well as the least-frequently-used (LFU) and random replacement policies. A simulation method is presented for any such policy that, on any trace of length N directed to a C line set, runs in O(C log N) time with high probability using N processors on the EREW model. The algorithms are simple, have very little space overhead, and are well suited for SIMD implementation     

Learning about tools in infancy.

These experiments explored the role of prior experience in 12- to 18-month-old infants' tool-directed actions. In Experiment 1, infants' use of a familiar tool (spoon) to accomplish a novel task (turning on lights inside a box) was examined. Infants tended to grasp the spoon by its handle even when doing so made solving the task impossible (the bowl did not fit through the hole in the box, but the handle did) and even though the experimenter demonstrated a bowl-grasp. In contrast, infants used a novel tool flexibly and grasped both sides equally often. In Experiment 2, infants received training using the novel tool for a particular function; 3 groups of infants were trained to use the tool differently. Later, infants' performance was facilitated on tasks that required infants to grasp the part of the tool they were trained to grasp. The results suggest that (a) infants' prior experiences with tools are important to understanding subsequent tool use, and (b) rather than learning about tool function (e.g., hammering), infants learn about which part of the tool is meant to be held, at least early in their exposure to a novel tool. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Computational Chemistry Prototyping Environment

Evolving technologies, as exemplified by computational grids and Web services, have made it possible to solve new scientific problems that would not have been feasible previously. In order to make such advances available to the community in general and to be able to solve new problems, not necessarily from the same discipline, it is imperative to build tools that provide a common user interface in order that application programmers and users do not have to be concerned with particulars of Web services and their underlying code, computational platforms, or with data file formats. We will describe our efforts in creating a computational chemistry environment that encompasses a general scientific workflow environment, a domain specific example for quantum chemistry, our ongoing design of a workflow user interface, and our efforts at database integration.     

Selective interference with class I major histocompatibility complex presentation of the major immediate-early protein following infection with human cytomegalovirus

Responses of cytotoxic T-cells (Tc) to human cytomegalovirus (CMV) represent the predominant mechanism by which hosts resist CMV infection. The CMV major immediate-early protein (IE) is present throughout the virus replicative cycle. Studies were performed to determine whether Tc specific for IE effectively lyse CMV-infected targets and are thus capable of providing protective immunity against infection. After in vitro stimulation of peripheral blood mononuclear cells with CMV-infected autologous fibroblasts, Tc specific for IE were not readily detectable in CMV-reactive polyclonal Tc lines. However, after stimulation of peripheral blood mononuclear cells with cells selectively expressing IE, weak but detectable IE-specific Tc responses were observed. The frequency of IE-specific Tc clones derived from cultures stimulated with IE-expressing cells was 50 to 100 times lower than the frequency of Tc clones specific for other CMV proteins isolated from cultures stimulated with CMV-infected cells. All of the IE-specific Tc clones, which efficiently lysed targets selectively expressing IE, demonstrated minimal lysis of CMV-infected fibroblasts, despite abundant IE expression in these target cells. In contrast to these results with IE, other viral proteins were efficiently presented during all phases of CMV infection. These data suggest that CMV has evolved a unique mechanism for selectively limiting the presentation of the potentially immunogenic IE protein, which may preclude IE-specific Tc from providing protective immunity to CMV infection.