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The filtration of phi X 174, MS2, and T4 bacteriophages out of tap water and secondary effluents was performed by rapid sand filtration. The viruses were characterized, and the influence of their microscopic characteristics on filterability was examined by comparing retention values, residence times, attachment, and dispersion coefficients calculated from(More)
A new method for the study of pathogen transport in porous media is presented. The method is based on conjugation of fluorescent dyes to target bacteriophages and application of the modified bacteriophages for tracer studies. We demonstrate that the relevant transport determining properties of Rhodamine and several fluorescein-labeled phages are practically(More)
Viral transport in deep-bed sand filters was studied by a new method that enables rapid and simple quantitation of labeled viruses. The residence time distribution (RTD) of viruses in the bed was compared to the RTD of a fluorescein dye under conditions that simulate a filter run. The characteristics of the RTD curves for the free dye and the labeled(More)
Studies of electrostatic repulsion in ultrafiltration membranes are limited to applications of different organic compounds carrying a set of unique characteristics, or to changes of general water parameters such as ionic strength and pH. The proposed method of deliberate alteration of surface charge of organic molecule by succinylation or by guanidination(More)
Microorganisms are retained by ultrafiltration (UF) membranes mainly due to size exclusion. The sizes of viruses and membrane pores are close to each other and retention of viruses can be guaranteed only if the precise pore diameter is known. Unfortunately and rather surprisingly, there is no direct method to determine the membrane pore size. As a result,(More)
Tracer experiments were carried out in a naturally discrete-fractured chalk core with solute tracers Li(+) and Br(-), and colloidal tracers of two origins-bacteriophages (MS2, ϕX174 and T4) and fluorescent latex microspheres. The colloidal tracers were either ∼20 nm (MS2, ϕX174 and microspheres) or ∼200 nm (T4 and microspheres) in size. Both solute and(More)
Penetration of viruses through soils is governed by the processes of transport, reversible adsorption, accumulation and inactivation. Until now, it was difficult to decouple the latter two processes and accurately predict viral fate. The present work describes a novel method-tracer studies with a mixture of native and fluorescent-dyed bacteriophages-that(More)
Cryogenic "trapping" was used to obtain the first TEM images of self-assembled monolayers of inorganic anions on a gold nanoparticle. This unique structural information makes it possible to study the formation of a protecting-ligand shell at an unprecedented level of detail. The protecting ligands are polyoxometalates (POMs; alpha-X(n+)W(12)O(40)((8-n)-),(More)
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