Analytical methods for probabilistic short-circuit studies

Probabilistic short-circuit design of substation equipment requires the probability density distribution of short-circuit current magnitudes. This distribution can be calculated for specific systems using Monte Carlo simulation or the analytical methods described in this article. The analytical methods are easily formulated and require much reduced computational effort, although in certain cases these advantages may be offset by a somewhat reduced accuracy of results.     

Thames Water Utilities'Emergency Response to the Bishopsgate Bomb in April 1993

ABSTRACT The paper describes Thames Water Utilities'response to the Bishopsgate bomb which exploded in the City of London in April 1993. Particular emphasis is placed on the procedures and control measures which were adopted to manage the activities associated with severe damage to water mains and sewers. The need for exceptional health and safety measures, whilst working in a potentially extremely dangerous environment, are highlighted.
Technical aspects of the repair work are discussed including the coordination with other utilities and the difficulties experienced in locating the position of underground apparatus which was subjected to bomb damage.     

Monte Carlo simulations derived from direct observations of individual bacteria inform macroscopic migration models at granular porous media interfaces

Motile bacteria accumulated at the interface between an aqueous solution and a polymer gel suspension. The gel suspension was produced using Gelrite and contained 50-500 microm semisolid gel particulates in aqueous buffer. Smooth-swimming (HCB437) and wild-type (HCB1) Escherchia coli displayed normal swimming behaviors in the aqueous buffer but exhibited no translational motion when obstructed by the semisolid particulates of the gel suspension. Translational motion immediately resumed after the bacteria reoriented in a direction away from the particle surfaces. These observations were incorporated into Monte Carlo simulations that linked individual swimming properties to macroscopic bacterial distributions. The simulations suggested that the apparent surface area of the porous media influenced the degree of bacteria/surface interactions and thatthe mechanism of surface association could concentrate bacterial populations based upon the physical constraints of the porous media system. Population distributions from the Monte Carlo simulations matched a 1-D transport model that characterized the bacteria/surface interactions as an adsorption-like process even though direct observations suggested no physical attachment was occurring. Consequently, the 1-D transport model provided a semiquantitative approach to approximate bacterial migrations within porous media systems. Results suggest that the self-propulsive nature of bacteria can produce nondiffusive migration patterns within high-surface area environments.     

Hydronium Copper(II)‐tris(5‐nitrotetrazolate) Trihydrate – A Primary Explosive

The long‐time elusive structure of the acid copper(II) salt intermediate in the production of DBX‐1 is presented. The single‐crystal X‐ray shows infinite chains of copper(II) ions complexed by six 5‐nitrotetrazolate anions are aligned along the sixfold axis. Hydronium ions are located on the threefold axis with additional neutral water molecules.     

Relational benefits and manufacturer satisfaction: an empirical study of logistics service in supply chain

Using data collected from US manufacturing firms, this research evaluates logistics service from the eyes of manufacturers. The study leads to a close look at how manufacturers view third party logistics services to provide important strategic and operational values to manufacturers. The results indicate that the building of a long-term relationship is mediated by trust and commitment from manufacturers. When manufacturers believe that the logistics service provider is honest and passionate, and care about their business, they will make a commitment toward a long-term business relationship.     

An In Vitro Evaluation of Fenugreek Mucilage as a Potential Excipient for Oral Controlled-Release Matrix Tablet

A polysaccharide mucilage derived from the seeds of fenugreek, Trigonella foenum-graceum L (family Fabaceae) was investigated for use in matrix formulations containing propranolol hydrochloride. Methocel® hypomellose K4M was used as a standard controlled release polymer for comparison purposes. In this study the effect of lactose on the release behaviour of propranolol hydrochloride from matrices formulated to contain the fenugreek mucilage also was investigated. An increase in concentration of the mucilage in matrices resulted in a reduction in the release rate of propranolol hydrochloride comparable to that observed with hypomellose matrices. The rate of release of propranolol hydrochloride from fenugreek mucilage matrices was mainly controlled by the drug:mucilage ratio. However, the mechanism of release from matrices containing drug:mucilage ratios of 1:1, 1:1.25, 1:1.5, and 1:2 remained the same. The kinetics of release, utilising the release exponent n, showed that the values of n were between 0.46–0.57 indicating that the release from fenugreek mucilage matrices was predominantly by diffusion. The presence of lactose in matrices containing mucilage increased the release rate of propranolol hydrochloride. This is due to a reduction in tortuoisity and increased pore size of channels caused by lactose through which propranolol diffuses and therefore diffusion of water into the tablet is facilitated.     

Inter-individual differences in the ability of human milk-fat extracts to enhance the genotoxic potential of the procarcinogen benzo[a]pyrene in MCF-7 breast cells

Environmental factors are believed to play an important role in cancer aetiology. Whether environmental pollutants act in isolation or in combination within mixtures remains unclear. Four human milk-fat extracts (from resident U.K. women) were screened for levels of organochlorinated and brominated compounds prior to being tested (1-50 mg-equiv) for micronucleus (MN)-forming activity in MCF-7 cells. Using the cytokinesis-block micronucleus assay, micronuclei (MNi) were scored in 1000 binucleate cells per treatment. Cell viability (% plating efficiency) and immunohistochemical detection of p53 induction were also measured. The effects of treatment with 1 mg-equiv of extract in combination with benzo[a]pyrene (BP) were also examined. BP-DNA adducts were detected and quantified by 32P-postlabeling analysis. Dose-related increases in MNi independent of pollutant concentrations were induced by milk-fat extracts. All four extracts elevated the percentage of p53 positive cells, although not always in a dose-related fashion. Some combinations resulted in profound low-dose-induced increases in MNi and significant elevations in the percentage of p53 positive cells, which occurred without further reduction in cell viability or mitotic rate. When one particular extract was combined with BP, a 100-fold increase in BP-DNA adducts was detected as compared with the levels induced by BP alone; an effect not induced by other extracts. This adduct-enhancing extract was fractionated into 14 fractions that were subsequently tested (1 mg-equiv of original extract) in combination with 0.01 microM BP. Fraction 1, into which nonpolar pollutants mostly eluted, enhanced MN-forming activity with BP. Surprisingly, the more polar and less likely to contain fat-soluble pollutants fractions 5 and 8 also enhanced MN-forming activity. No identifiable pollutants were present in these fractions. The results suggest that different environmental pollutants present in human tissue may influence the susceptibility of target cells to initiating events.