Disinfection performance of Fe(VI) in water and wastewater: a review.

Ferrate(VI) [FeVIO4(2-), Fe(VI)] has excellent disinfectant properties and can inactivate a wide variety of microorganisms at low Fe(VI) dosages. The final product of Fe(VI) is Fe(III), a non-toxic compound. The treatment by Fe(VI) does not give any chlorination by-products, which makes Fe(VI) an environmentally-friendly ion. The results demonstrate that Fe(VI) can inactivate Escherichia coli (E. coli) at lower dosages or shorter contact time than hypochlorite. Fe(VI) can also kill many chlorine resistant organisms, such as aerobic spore-formers and sulphite-reducing clostridia, and would be highly effective in treating emerging toxins in the aquatic environment. Fe(VI) can thus be used as an effective alternate disinfectant for the treatment of water and wastewater. Moreover, Fe(VI) is now becoming economically available in commercial quantities and can be used as a treatment chemical to meet the water demand of this century. This paper reviews the potential role of Fe(VI) as disinfectant in water and wastewater treatment processes.     

A Dynamic Dictionary for Priced Information with Application

In this paper we design a dynamic dictionary for the priced information model initiated by Charikar et al. Assume that a set S consisting of n elements is given such that each element has an associated price, a positive real number. The cost of performing an operation on elements of S is a function of their prices. The cost of an algorithm is the sum of the costs of all operations it performs. The objective is to design algorithms which incur low cost. In this model we propose a dynamic dictionary, supporting search, insert and delete, for keys drawn from a linearly ordered set. As an application we show that the dictionary can be used in computing the trapezoidal map of a set of line segments, a fundamental problem in computational geometry.     

Thermoplastic elastomeric composition based on maleic anhydride–grafted ground rubber tire

Ground rubber tire (GRT) powder was maleated in an internal mixer using maleic anhydride and dicumyl peroxide at 160°C. Maleated GRT was characterized by using X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, wettability, and differential scanning calorimetry. The physical properties of the dynamically vulcanized 60 : 40, rubber : plastic composition based on acrylated high‐density polyethylene as the plastic phase and ethylene propylene diene rubber containing maleated GRT as the rubber phase were found to be greater than the corresponding composition containing nonmaleated GRT. The blend was found to be reprocessable, like themoplastic elastomers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 370–378, 2002; DOI 10.1002/app.10348     

Human erythrocytes bearing electroinserted CD4 neutralize infection in vitro by primary isolates of human immunodeficiency virus type 1

Human erythrocytes bearing electroinserted full-length CD4 (RBC-CD4) can bind and fuse with a laboratory strain of human immunodeficiency virus type 1 (HIV-1) or with T cells infected by HIV-1. Here we show that RBC-CD4 neutralize primary HIV-1 strains in an assay of cocultivation of peripheral blood mononuclear cells (PBMC) from HIV-1-infected persons with uninfected PBMC. RBC-CD4 inhibited viral p24 core antigen accumulation in these cocultures up to 10,000-fold compared with RBC alone. Viral p24 accumulation was inhibited equally well when measured in culture supernatants or in call extracts. The inhibition was dose-dependent and long-lived. Two types of recombinant CD4 tested in parallel were largely ineffective. The neutralization of primary HIV-1 by RBC-CD4 in vitro was demonstrated in PBMC cultures from 21 of a total of 23 patients tested at two independent sites. RBC-CD4 may offer a route to blocking HIV-1 infection in vivo.     

Defects in molecular beam epitaxial GaAs grown at low temperatures

We have utilized a variable energy positron beam and infrared transmission spectroscopy to study defects in GaAs epilayers grown at low temperatures (LT-GaAs) by molecular beam epitaxy. We have measured the Doppler broadening of the positron-electron annihilation gamma ray spectra as a function of positron implantation energy. From these measurements, we have obtained results for the depth profiles of Ga monovacancies in unannealed LT-GaAs and Ga monovacancies and arsenic cluster related defects in annealed LT-GaAs. We have also studied the effects of the Si impurities in annealed LT-GaAs. The infrared transmission measurements on unannealed LT-GaAs furnish a broad defect band, related to As antisites, centered at 0.370 eV below the conduction band.     

Analysis of posterior availability distributions of series and parallel systems

The lifetime distribution of an engineering system is a powerful tool for analysing the system in respect of its reliability characteristics. The analysis can be improved if the experimenter has, and is able to combine, the prior belief about the system with the operational or experimental data. Moreover, in many situations, the operational data with the complete system may either be costlier or non-existent. The problem can still be tackled by making use of such information available on the subunits or components of the system. Pursuing these concepts, the present study deals with the analysis of posterior availability distributions for a series and a parallel system. Time truncated failure and repair information and prior beliefs about the failure and repair rates of the compoents of the systems have been employed in the analysis.