Composting of miscible cellulose acetate propionate-aliphatic polyester blends

A series of miscible blends consisting of cellulose acetate propionate (CAP) and poly(ethylene glutarate) (PEG) or poly(tetramethylene glutarate) (PTG) were evaluated in a static bench-scale simulated municipal compost environment. Samples were removed from the compost at different intervals, and the weight loss was determined before evaluation by gel permeation chromatography, scanning electron microscopy, and¹H NMR. The type of polyester (PEG versus PTG) in the blend made no difference in composting rates. At fixed CAP degree of substitution (DS), when the content of polyester in the blend was increased, the rate of composting and the weight loss due to composting increased. When the CAP was highly substituted, little degradation was observed within 30 days and almost all of the weight loss was ascribed to loss of polyester. Although the polyester was still observed to degrade faster, when the CAP DS was below approximately 2.0, both components are observed to degrade. The data suggests that initial degradation of the polyester is by chemical hydrolysis and the rate of this hydrolysis is very dependent upon the temperature profile of the compost and upon the DS of the CAP.     

Methods for control of indoor air quality

This report presents results of a review of available methods for control of environmental hazards applied to indoor air pollutants. Indoor air pollution originates from transport of ambient outdoor air contaminants into occupied spaces by natural infiltration ventilation, or by mechanical ventilation using outdoor makeup air, plus contributions from indoor emission sources. When air exchange with the external ambient environment is reduced to conserve energy, contributions from indoor emission sources may dominate indoor air pollutant levels. This paper identifies alternative methods available to control indoor air pollutant exposures. The performance characteristics of ventilation systems and of air cleaning devices used in mixed modes for ventilation of occupied spaces are described. Models for predicting effectiveness of several alternative modes are reviewed, with field trial validation results cited where available. Results of previous confined-space studies are briefly reviewed as points of departure for consideration of necessary air quality, ventilation, and air cleaning. Understanding of indoor air contaminant generation and controls is aided by examination of earlier studies of indoor air quality, using modern perspectives on occupational environmental health and hygiene.     

Behaviour of Dioxins, Furans and Metals Associated with Stabilized Msw Combustor Ash in Sea Water

This report presents the results of a research programme designed to examine the engineering and environmental acceptability of stabilizing municipal solid waste (MSW) combustor ash for artificial reef construction. Municipal solid waste combustor ash was combined with Portland cement to form solid blocks using conventional construction block making technology. the resultant stabilized combustor ash (SCA) blocks were used to construct an artificial habitat in Conscience Bay, Long Island Sound, New York and compared to identical concrete blocks, fabricated using natural aggregates. Over a 4.5 year period divers periodically returned to the site to monitor the interaction of SCA blocks with the marine environment and compare the performance of these blocks with the concrete control blocks. Results show that the SCA blocks retain their strength after prolonged sea water exposure. Contaminants of environmental concern, including metals, dioxins and furans, were retained within the cementitious matrix of the SCA blocks after prolonged sea water submersion. in addition, organisms growing on the surfaces of the SCA blocks did not accumulate contaminants from the blocks.     

Preimplantation genetic diagnosis for single gene disorders: experience with five single gene disorders

We report our experience of 14 preimplantation genetic diagnosis (PGD) cycles in eight couples carrying five different single gene disorders, during the last 18 months. Diagnoses were performed for myotonic dystrophy (DM), cystic fibrosis (CF) [ΔF508 and exon 4 (621+1 G>T)], fragile X and CF simultaneously, and two disorders for which PGD had not been previously attempted, namely neurofibromatosis type 2 (NF2) and Crouzon syndrome. Diagnoses for single gene disorders were carried out on ideally two blastomeres biopsied from Day 3 embryos. A highly polymorphic marker was included in each diagnosis to control against contamination. For the dominant disorders, where possible, linked polymorphisms provided an additional means of determining the genotype of the embryo hence reducing the risk of misdiagnosis due to allele dropout (ADO). Multiplex fluorescent polymerase chain reaction (F-PCR) was used in all cases, followed by fragment analysis and/or single-stranded conformation polymorphism (SSCP) for genotyping. Embryo transfer was performed in 13 cycles resulting in one biochemical pregnancy for CF, three normal deliveries (a twin and a singleton) and one early miscarriage for DM and a singleton for Crouzon syndrome. In each case the untransferred embryos were used to confirm the diagnoses performed on the biopsied cells. The results were concordant in all cases. The inclusion of a polymorphic marker allowed the detection of extraneous DNA contamination in two cells from one case. Knowing the genotype of the contaminating DNA allowed its origin to be traced. All five pregnancies were obtained from embryos in which two blastomeres were biopsied for the diagnosis. Our data demonstrate the successful strategy of using multiplex PCR to simultaneously amplify the mutation site and a polymorphic locus, fluorescent PCR technology to achieve greater sensitivity, and two-cell biopsy to increase the efficiency and success of diagnoses. Copyright © 2002 John Wiley & Sons, Ltd.     

SEQUENTIAL WATER REUSE EFFECT ON STREAM SALINITY1

ABSTRACT: Sequential water reuse by various users, i.e., municipal, industrial, agricultural, is common practice in all river systems. In the arid and semiarid western United States where streams are not large and water demands are high relative to the virgin water supply, the practice causes a reduction in stream flow and an increase in stream salinity. This paper outlines a quick and easy application of the materials balance principle to approximate the effects of increasing the level of sequential reuse on residual stream flow and salinity.     

Viruses in surface and drinking waters

Over 114 different human enteric viruses are known. They are all excreted into sewage, and opportunities exist for them to find their way into water distribution systems. The characteristics of the illnesses caused by enteric viruses make their transmission by water difficult to recognize. Methods are not available for isolating all of the enteric viruses from water, so that finding any type of human virus in drinking water is an indication that other types may also be present. With improvements in technology, our laboratory has recently been able to detect group B coxsackieviruses, rotaviruses, and hepatitis A virus in chlorinated drinking water. At present, there are no uniform methods for concentrating, isolating, and identifying viruses in water. Emphasis should be placed on seeking uniformity in methods so that standards can be set for viruses in water.     

WATER RESOURCES AS SOCIAL PROBLEMS1

ABSTRACT. Evidence from 1969 studies in Virginia and Ohio suggests that neither community leaders nor the general public are likely to define water related problems as major problem areas. An examination of the components of a social problem tends to indicate that water problems have not moved beyond a level of minimal public concern. When respondents were willing to describe existing or potential water problems, perceptions as well as possible solutions were described in abstract rather than action-oriented terms. It is suggested that efforts to eliminate water resource problems are not likely to be effective until public concern moves to motivational and behavioral levels.