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Enteric viruses enter surface waters through discharge of sewage treatment plants. They have a high environmental resistance and persistence and have low infectious doses. The aim of this study was to investigate the efficiency of polishing pond in the removal of viruses and bacteria. The samples were taken approximately once a week at the influent of secondary treatment (n = 39), effluent of secondary treatment (n = 39), and polishing pond (tertiary treatment, n = 29). Human adenoviruses (HAdV) were detected in 82–100 % of wastewater samples, whereas 62–79 % of the samples were positive for human polyomavirus (HPyV). The median concentrations ranged from 6.8 × 103 genome equivalents/l (HAdV) to 6.0 × 103 genome equivalents/l (HPyV). The concentration of HAdV and HPyV did not change significantly during the wastewater treatment. For somatic coliphages and bacteria an overall reduction of 1.84–2.65 log10 has been detected. Based on the data collected, this type of tertiary treatment achieved a significant reduction in bacteria and phages, but not for viruses.

Controllability studies of the mechanical nonlinear dynamic systems such manipulators or air and water craft were continued. Controllability was previously studied disregarding the dynamics of the control drives of mechanical systems [1---5]. The present paper established a controllability criterion for the mechanical systems where the drive dynamics is considered explicitly. Controllability conditions having an obvious physical sense were established. As before, the controllability condition is related with domination of the control forces over any other generalized forces of weight, environmental resistance, and so on. If the drive dynamics is taken into account, then domination in the rate of force variation, that is, in the derivative, is required. Stated differently, the control drives must tolerate sufficiently fast changes in the control output, that is, control forces.

The random, two-dimensional network formed of electrically conducting nanoscale wires, called carbon nanotubes, is a transparent electronic material that can be fabricated using room-temperature printing or spraying technologies. Depending on the network density, networks with both metallic- and semiconducting-like attributes can be fabricated. Both display high conductivity, high carrier mobility and optical transparency. The networks also have high mechanical flexibility, robustness and environmental resistance. Application opportunities range from lightweight, transparent conducting films, to electrically conducting fabrics, to active electronic devices and sensors.

Based upon Antonovsky's conceptual model of resources as resistors to stress, seven personal and three environmental resistance resources are identified, and quantified. The resistance resources and measure of tension are used as the predictor variables in a stepwise multiple regression analysis to identify the factors which best predict stress. The four variables which are statistically significant in explaining variance in stress scores are satisfaction with family life, total number of life events experienced, age, and satisfaction with family finances.

The three-fibre method used for determining the adhesion between glass fibres and resin, has proved suitable for measuring the environmental effects on the bond strength. The environment used was hot water (95° C) treatment, the decreasing effect of which on the strength was not very clear. This method has two great advantages; it measures the actual bond strength and the environmental effect is directed efficiently on the bond. In this form, the method is only suitable for thermoset resins.

One of the primary factors influencing the research and development of rigid-rod polymers in the Materials Laboratory has been the excellent environmental resistance of this class of aromatic heterocyclic benzobisazole polymers. Thermal stability of these materials has been determined utilizing thermal analytical, Isothermal Aging and combined Thermal Gravimetric-Mass Spectrometry (TG-MS) techniques. Correlations between the thermal stability and chemical structure, varying substituent groups and processing conditions for these polymers have been observed. An overview of the thermal stability of these rigid-rod polymer systems is presented.

This review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include the cis- and trans-poly(p-phenylene benzobisoxazole) (PBO), the cis- and trans-forms of the corresponding poly(pphenylene benzobisthiazole) (PBT), and the structurally similar poly(5,5ʹ-bibenzoxazole-2.2ʹ-diyl-l,3-phenylene) (AAPBO) and poly(2,5-benzoxazole) (ABPBO) and their sulfurcontaining analogues. Because of their rigidity, these polymers become highly oriented in solution and some display liquid crystalline behavior. The purpose of this paper is to summarize the authorsʹ theoretical work on the structures, conformational energies, intermolecular interactions, electronic properties, electrical conductivity, and electrooptical properties of these chains, including, in some cases, the so-called articulated forms and the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.

The 35 papers contained in this collection detail efforts being made toward achieving environmental resistance of alloys and conserved usage of strategic and critical materials. An in-depth look is taken at the roles played by various alloying elements in providing desired microstructures, properties, and influences upon environmental attack. Also presented are applications and performances of alternate alloys in aqueous and high temperature gaseous and molten salt environments. The book is broken down into five key sections covering: 1) philosophies and status of programs designing alloys for resistance to various environmental and microstructural stability of some of these alloys systems, 2) applications in hot corrosion and sulfidizing environments, 3) applications in oxidizing conditions, 4) corrosion resistance in aqueous environments, and 5) other properties, such as physical and mechanical, which are necessary to evaluate overall alloy performance.

HUMAN populations have always proved favourite material for analysis by statisticians and others interested in mathematical theories of population growth. From the experimental aspect, however, humans are far from being ideal biological material, so that other animals, such as protozoa, mammals and insects, have to be used; although it does not yet appear to be fully realised how suitable the latter are for this type of work. The theory of bio tic potential and environmental resistance1 has done much to create a new interest in population studies in that it attempts to place the problem upon a quantitative experimental basis. Working with Tribolium confusum, Chapman demonstrated that, irrespective of the initial density, a point of equilibrium is eventually attained after which the population remains relatively constant, provided the floury medium is renewed frequently enough to remove waste products and maintain an abundance of food. He concludes that equilibrium is attained when the bio tic potential is equalled by the environmental resistance, and that the lack of population increase is not due to the absence of eggs or their infertility, but on account of the eating of eggs and pupae by the adult beetles.