Showing papers on "Water environment published in 1998"

Human enteric viruses in the water environment: a minireview.

Abstract: Summary Water virology started around half a century ago, with scientists attempting to detect poliovirus in water samples. Since that time, other enteric viruses responsible for gastroenteritis and hepatitis, among a great variety of virus strains, have replaced enteroviruses as the main target for detection in the water environment. Technical molecular developments, polymerase-chain reaction (PCR) amplification being the method of choice, enable the detection of fastidious health-significant viruses. However, shortcomings of molecular procedures include their potential incompatibility with concentration methods, indispensable to reduce the water sample volume to assay for viruses, and the inability to discern between infectious and non infectious material. On the other hand, these procedures are restrained to sophisticated laboratories and detection of alternative indicator organisms has been proposed. Bacterial indicators fail to give a reliable clue of the virological quality of water. Selected bacteriophage groups appear as a better choice for their use as virus indicators.

Anisotropic Intramolecular Backbone Dynamics of Ubiquitin Characterized by NMR Relaxation and MD Computer Simulation

Abstract: The anisotropy of rapid fluctuations of the peptide planes in ubiquitin is explored by combined 15N and 13C‘ nuclear spin relaxation measurements and molecular dynamics (MD) computer simulation. T1, T2, and NOE data were collected at B0-field strenghts corresponding to 400 and 600 MHz proton resonance. A 1.5-ns simulation of ubiquitin in an explicit water environment was performed using CHARMM 24. The simulation suggests that, for 76% of the peptide planes, the relaxation-active motion of the backbone 15N and 13C‘ spins is dominated by anisotropic Gaussian axial fluctuations of the peptide planes about three orthogonal axes. The dominant fluctuation axes are nearly parallel to the − axes. The remaining peptide planes belong to more flexible regions of the backbone and cannot be described by this type of motion alone. Based on the results of the computer simulation, an analytical 3D GAF motional model (Bremi, T.; Bruschweiler, R. J. Am. Chem. Soc. 1997, 119, 6672−6673) was applied to the experimental relax...

Adaptive plasticity in amphibian metamorphosis

Abstract: Amphibians exhibit extreme plasticity in the timing of metamorphosis, and several species have been shown to respond to water availability, accelerating metamor- phosis when their ponds dry. In this study we analyzed the plasticity of the developmental response to water volume reduction in the western spadefoot toad, Scaphiopus hammondii. Also, we attempted to identify the environmental cue(s) that may signal a desiccating larval habitat. We spawned adults in the laboratory and raised tadpoles in aquaria in a controlled environmental chamber. Water levels of aquaria were gradually reduced by removing water at the rate of 0.5-1 L/d; water in control aquaria was similarly disturbed but not removed. Tadpoles subjected to water volume reduction showed significant acceleration of meta- morphosis. The developmental acceleration depended on the rate of reduction of the water level; i.e., tadpoles exhibited a continuum of response. This developmental response did not result from thermal differences between treatments. Furthermore, the response was reversible in that refilling of the aquaria to the starting water level at various times following the onset of volume reduction resulted in restoration of body mass and a tendency to decelerate metamorphosis. Several lines of evidence suggest that the developmental re- sponse is due neither to the concentration of compounds in the water nor to chemical or physical interactions among conspecifics. Rather, the response appears to be related to the reduced swimming volume and perhaps the proximity to the water surface. When the water level is reduced, tadpoles reduce foraging, and food restriction of prometamorphic tadpoles maintained in a constant high water environment accelerated metamorphosis. Spadefoot toad tadpoles are a valuable model system for explaining both the proximate mechanisms (environmental cues and physiological responses) and the ultimate causes for adaptive phenotypic plasticity in amphibian metamorphosis.

Aging of Cryptosporidium parvum oocysts in river water and their susceptibility to disinfection by chlorine and monochloramine.

Abstract: Cryptosporidium parvum oocysts were aged in waters from both the St. Lawrence River and the Ottawa River. In situ survival experiments were carried out by incubating the oocysts in either dialysis cassettes or microtubes floated into an overflow tank. A significant portion of the oocysts survived in the test waters for several weeks. Oocyst survival in the St. Lawrence River was better in membrane-filtered (0.2 microm-pore diameter) water than in unfiltered water, suggesting that biological antagonism may play a role in the environmental fate of the parasite. Oocysts aged in river waters under in situ conditions and control oocysts kept refrigerated in synthetic water (100 ppm as CaCO3); pH 7.0) were subjected to the same disinfection protocol. Aged oocysts were at least as resistant as, if not more resistant than, the control oocysts to disinfection. This indicates that the oocysts surviving in the water environment may be just as difficult to inactivate by potable water disinfection as freshly shed oocysts. Therefore, water treatment should not be based on the assumption that environmental oocysts may be more easily inactivated than freshly shed oocysts. First-order kinetics die-off rates varied from one river to another (from 0.013 to 0.039 log(10).day(-1)) and from one experiment to another with water from the same river collected at different times. Calculation of the die-off rates based on either in vitro excystation or in vitro excystation in combination with total counts (overall die-off rates) showed that the assessment of oocyst viability by microscopic methods must account for the total oocyst loss observed during long-term inactivation assays of river waters.

Ecology of mixotrophic flagellates with special reference to Chrysophyceae in Danish lakes

Abstract: Although intensively studied in Danish lakes, Chrysophytes constituted only a minor part of the phytoplankton in the lakes studied in the Danish Survey Programme of the Water Environment during 1989–94. However, in the lakes Holm So, Magleso by Brorfelde, and Bastrup So, populations of naked and loricated (mixotrophic) Chrysophytes exhibited 2–3 maxima yr−1 and contributed 2–36% to the yearly mean phytoplankton biomass. The mixotrophic Chrysophyte biomass in these lakes increased with increasing biomass of the entire phytoplankton community up to 5 mm3 1−1. Above this phytoplankton biomass, the mixotrophic Chrysophyte biomass became irregular and scarce.

Submarine deployable vertical launch spar buoy

Abstract: The present invention relates to a system and a method for launching an anautical vehicle from a submerged platform such as a submarine. The system includes a buoy configured to be deployed from a launching tube onboard the submerged platform, which buoy contains the aeronautical vehicle to be launched. The system further includes a gas generator for creating a pressure force which causes the buoy with the encapsulated aeronautical vehicle to be deployed from the launch platform. Once deployed, the buoy inflates a buoyancy device for putting the buoy in a partially submerged position and damping plates for resisting vertical movement of the buoy and wave motion. The buoy has a ballast arrangement for maintaining it in a substantially vertical orientation. The buoy further has an antenna for receiving commands to launch the aeronautical vehicle. The method for launching the aeronautical vehicle from the underwater platform broadly comprises the steps of: providing a buoy containing an aeronautical vehicle; deploying the buoy from the underwater platform into a water environment where the buoy is partially submerged beneath the surface of the water in a substantially vertical position; and launching the vehicle from the buoy while the buoy is in the substantially vertical position.

On the Chemo-Mechanical Polishing (CMP) of Si3N4 Bearing Balls With Water Based CeO2 Slurry

Abstract: Among various abrasives investigated for the chemo-mechanical polishing (CMP) of Si 3 N 4 balls (Jiang, 1998), cerium oxide (CeO 2 ) was found to be the most effective polishing medium (even superior to Cr 2 O 3 , Bhagavatula and Komanduri, 1996), yielding an extremely smooth and damage-free surface with a finish R a of 4 nm and R t of 40 nm. In this investigation, the underlying reasons for the superior finish with CeO 2 were investigated. Various chemical reactions involved in CMP of Si 3 N 4 balls with CeO 2 were investigated (Gibbs free energy minimization) and a mechanism for the CMP is proposed. The two important functions that CeO 2 performs in the CMP of Si 3 N 4 are: I. It participates directly in the chemical reaction (oxidization-reduction reaction) with Si 3 N 4 workmaterial leading to the formation of thin SiO 2 layer, 2. The hardness of CeO 2 is closer to that of the thin SiO 2 layer formed on Si 3 N 4 but significantly lower than Si 3 N 4 workmaterial (1/3). It can thus remove the brittle SiO 2 reaction product effectively without damaging the Si 3 N 4 substrate as no abrasion can take place by CeO 2 on Si 3 N 4 . The kinetic action, which involves the removal of the reaction products from the interface by subsequent mechanical action of flowing water and CeO 2 is critical to CMP. The chemical reaction could proceed on a continuing basis so long as the passivating layers are removed by the mechanical action at the same time. CeO 2 is found to be very effective in a water environment (hydrolysis) leading to the formation of additional SiO 2 by reacting with Si 3 N 4 thereby enhancing the CMP of Si 3 N 4 . Several similarities between polishing of Si 3 N 4 and glass (SiO 2 ) (Cook, 1990), including the polishing environment (CeO 2 plus the magnetic fluid, pH value 6) and the mechanism of polishing were observed. Also, after investigatin g various reaction species in the CMP of Si 3 N 4 with CeO 2 and Cr 2 O 3 , the former is found to be much safer from an environmental point of view (Reddy and Komanduri, 1998).

Effects of grain size and ceria addition on ageing behaviour and tribological properties of Y-TZP ceramics

Abstract: The influence was investigated of ceria addition and the grain size on ageing and wear behaviour of Y-TZP ceramics. Two types of ceramics were studied: ZY5 (95 mole% ZrO2 and 5 mole% YO1·5) and ZY4Ce4 (92 mole% ZrO2, 4 mole% YO1·5, and 4 mole%CeO2). Each ceramic was sintered with grain sizes of 0·18 μm (95% dense) or 0·5 μm (98% dense). Only the ZY5 ceramic with a grain size of 0·5 μm showed degradation to monoclinic zirconia (= ageing) after a treatment in water at 180°C. This ceramic was also the only one in which a phase transformation was observed after wear tests in water for a pin (SiC) on plate test configuration. However, this transformation was found not to affect the wear rate. Wear mechanisms were investigated for testing in dry nitrogen and water environment.

The effect of marine environment on a vinyl ester resin and its highly filled particulate quartz composites

Abstract: The accelerated effects of immersion in seawater at 60°C, in comparison to distilled water, on a vinyl ester resin and on its highly quartz particles filled system were studied. The studied resin was cured at room temperature for 48 h and postcured at 100°C for 12 h, and the filled system contained 93 wt % quartz particles of a wide size distribution, either as received or silane-treated. The immersion in water results mainly in further curing and some extraction of low molecular substances, as reflected by the flexural mechanical properties and the DSC thermograms. The silane coupling agent treatment of the filler significantly improves the composite properties and its resistance to the water environment. No practical difference was observed in any of the studied systems between the effects of sea and distilled water, as tested by the immersion in boiling water for 48 h. Weatherometer conditions, cycles of ultraviolet radiation at 60°C and water condensate at 50°C, for up to 1000 h, also cause postcuring effects, without extractables' leaching effects. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2229–2234, 1998

Molecular dynamics simulation of a zif268-dna complex in water. spatial patterns and fluctuations sensed from a nanosecond trajectory

Abstract: In this paper, with the help of a nanosecond-long molecular dynamics trajectory, we show that a fully charged protein−DNA system (Zif268-DNA) in a water environment can be simulated with a general force field (GROMOS) if solvation and counterion effects are appropriately represented. A model exhibiting ionic-atmosphere effects on mobile counterions (Tapia, O.; Velazquez, I. J. Am. Chem. Soc. 1997, 119, 5934−5938) was implemented. The root-mean-square deviations (rmsds) with respect to X-ray structure for the full complex, the protein, and the 12-base pair consensus sequence were 2.0, 1.95, and 1.35 A, respectively, while the counterions displayed an rmsd from the initially equilibrated position of 1.2 A. The mean-square fluctuation with respect to the average structure correlated with temperature factors for the protein and DNA; the agreement in trend is good. The results show that GROMOS87 force field with an appropriate representation of coion (ion atmosphere) effects on the counterions, and corrections...

Underwater apparatus for an aquarium and related methods

Abstract: Novel structures and methods are disclosed for creating and maintaining an underwater air chamber beneath a volume of water within a conventional aquarium for access by amphibious life within the aquarium to permit the amphibious life to selectively leave a water environment for a dry environment. In one embodiment, the underwater air chamber includes a hood secured to a base which defines a hollow chamber. After the apparatus is submerged in an aquarium, pressurized gas is introduced into the hollow chamber to create a dry environment within the hollow chamber. A gas effluent control is associated with the hood to selectively release the gas under pressure from within the chamber. An entryway into the chamber is also formed in the hood to permit amphibious life to selectively enter and exit the chamber, as well as to permit larger air bubbles to escape from within the air chamber. Another embodiment discloses an underwater air chamber formed integrally with an aquarium. Structures and methods are also disclosed for delivering a food object to a submerged air chamber from above the water surface of an aquarium.

Global warming : the potential impact on Japan

Abstract: 1 Climate Change Projections.- Summary.- 1.1 Introduction.- 1.2 Global-scale climate change projection.- 1.2.1 Emission scenarios of GHGs.- 1.2.2 Projections of future climate change.- 1.3 Climate change projections for Japan.- 1.3.1 Changes in temperature and precipitation.- 1.3.2 Changes in meteorological phenomenon indigenous to Japan.- 1.4 Future subjects.- References.- 2 Impacts on Natural Ecosystems.- Summary.- 2.1 Introduction.- 2.2 Impacts on mountainous region.- 2.2.1 Impacts on geomorphological processes of mountains.- 2.2.2 Impacts of global warming on forest distribution.- 2.3 Impacts of global warming on grasslands in Japan.- 2.3.1 Characteristics and vulnerability of grassland in Japan.- 2.3.2 Effects of global warming and human impact on grasslands in Japan.- 2.3.3 Future problems.- 2.4 Desertification: Effects on Japan across national borders.- 2.4.1 Desertification.- 2.4.2 Desertification in China.- 2.4.3 Impact on Japan.- 2.5 Impacts on wetlands.- 2.5.1 Wetlands characteristics and fragility.- 2.5.2 Effects of warming and human activities.- 2.6 Impacts on biodiversity and nature conservation areas.- 2.6.1 Warming and rare species, extinction of distributionally-bound species.- 2.6.2 Warming-induced degradation of conservation areas.- 2.6.3 Compound effects from warming and human activity.- References.- 3 Impacts on Agriculture, Forestry and Fisheries.- Summary.- 3.1 Introduction.- 3.2 Importance and vulnerability.- 3.2.1 Agriculture.- 3.2.2 Forest and forestry.- 3.3.1 Fisheries.- 3.3 State-of-art in agriculture, forestry, and fisheries research sector.- 3.3.1 Agriculture.- 3.3.2 Forest and forestry.- 3.3.3 Fisheries.- 3.4 Future research needs.- 3.4.1 Agriculture.- 3.4.2 Forest and forestry.- 3.4.4 Fisheries.- References.- 4 Impacts on Hydrology / Water Resources and Water Environment.- Summary.- 4.1 Introduction.- 4.2 Hydrology and water resources.- 4.2.2 Effect of warming on hydrology and water Resource/ countermeasures to warming.- 4.2.3 River flow predictions based on warming scenarios and long-term runoff models.- 4.2.4 Evaluation of effects based on Meteorological Agency general circulation model and Ministry of Construction, mesoscale hydro-meteorological models.- 4.2.5 Evaluation of effects based on CRIEPI regional climate model.- 4.2.6 Effects on snow and ice.- 4.3 Freshwater ecosystem.- 4.3.1 Characteristics of freshwater ecosystem in Japan.- 4.3.2 Effects of climatic warming on freshwater ecosystem in Japan.- 4.4 Coastal and marine environment.- 4.4.1 Characteristics of coastal and marine environments.- 4.4.2 Impacts on coastal and marine environments.- 4.5 Future research needs.- References ..- 5 Impacts on Infrastructure and Socioeconomic System.- Summary.- 5.1 Introduction.- 5.2 Present situation and problems regarding coastal zones, human settlements, social infrastructure, and industrial activities.- 5.2.1 Coastal zones.- 5.2.2 Infrastructure.- 5.2.3 Industry and energy.- 5.3 Researches on vulnerability of coastal zones, human settlement, infrastructure, and industrial activities.- 5.3.1 Impacts on coastal zones.- 5.3.2 Impacts on human settlement.- 5.3.3 Impacts on infrastructures.- 5.3.4 Impacts and energy sector.- 5.4 Future research needs.- References.- 6 Impacts on Human Health.- Summary.- 6.1 Direct Impacts of global warming on human health in Japan.- 6.1.1 Introduction.- 6.1.2 Impacts on heat waves on human health.- 6.1.3 Possible adaptability to heat stress.- 6.2 Impacts on vector-borne diseases.- 6.3 Impacts of warming on mortality.- 6.3.1 Introduction.- 6.3.2 Important issues for Japan.- 6.3.3 Recent research on mortality and temperature.- 6.3.4 Future research needs.- References.- 7 Vulnerability of Japan to Climate Change.- Summary.- 7.1 Introduction.- 7.2 Vulnerability to extreme climate events in Japan.- 7.2.1 Definition of extreme events.- 7.2.2 Description of extreme events in IPCC Second Assessment Report.- 7.2.3 Vulnerability of Japan to extreme events.- 7.2.4 Examples of vulnerability.- 7.3 Impacts of global warming on environmental quality.- 7.3.1 Impacts on atmospheric environment.- 7.3.2 Combined impacts of global warming and local environmental pollution.- 7.4 Impact of hot summers in 1994 and 1995.- 7.4.1 Characteristics of climate/weather in 1994 and 1995.- 7.4.2 Factors affected by hot summers.- 7.4.3 Potential impacts of global warming on daily living.- 7.5 Future research needs.- References.

Reverse Micelle Systems Composed of Water, Triton X-100, and Phospholipids in Organic Solvents

Abstract: Catalysis, stability, and thermostability of yeast hexokinase were determined in the microenvironments of two organic solvent/Triton X-100/phospholipids systems. In the abscence of enzyme, phase diagrams showed two transparent/turbid transitions, and reverse micelles were only observed in the second region of transparency (T2), where particle size as a function of water content shows a minima (see previous paper in this issue). In the present work, enzyme activity was detected throughout the four regions of the phase diagrams of these systems. Catalysis increased with water content; nevertheless, the maximum activities that were reached in the toluene and propylbenzene systems were 30 and 1.6%, respectively, of the activity in all aqueous media. Because in the T2 region in the propylbenzene system, micelles are much smaller than in toluene (see preceding paper), it would appear that expression of catalysis depends on the size of the micelles. However, a comparison of the dimensions of hexokinase and those of reverse micelles in the T2 region, suggests that in this region, hexokinase entrapment increases the inner volume of the micelle. High enzyme thermostability was only observed in the first transparent region (T1) of the system that contained phospholipids. In this region, hexokinase induced the formation of reverse micelles from dispersed surfactant monomers. There is a striking similarity in the dimensions of hexokinase entrapped in reverse micelles as determined by dynamic light scattering measurements in the T1 region with those of hexokinase as obtained from X ray diffraction studies of the enzyme in a crystalline environment. This suggest that high thermostability, and low catalytic rates result from restrictions in mobility imposed by a low water environment.

Differential hydrophone assembly

Abstract: A differential hydrophone assembly includes a ceramic hydrophone for disption in a water environment and comprising first and second hemispherical piezoelectric sections, a polarized ceramic member disposed in each section, a positive electrode and a negative electrode disposed in each section, an output conductor extending from each of the electrodes, such that a first pair of the conductors extend from a first of the ceramic members, and a second pair of the conductors extend from a second of the ceramic members, the first pair of conductors being discrete from the second pair of conductors The assembly further includes a differential summing amplifier for disposition in a second environment removed from the water environment and electrically connected to the first and second pairs of conductors The assembly is adapted to sum acoustic signals produced by changes in pressure in the water environment and transform the acoustic signals into two electrical signals of opposite polarities from which common mode noises are nulled to provide a differential hydrophone output

The carrying capacity of municipal water environment and its case study

Abstract: This paper had made analyse of the concept,nature,function and quantitative description method of the carrying capacity of municipal water environment by means of the systematic study method. It also has made the case study with the systemic dynamic simulation method and the forecast and optimization of the adjustment policy variables with the variation of the carrying capacity indices of water environment. Eventually satisfactory conclusions are obtained.

Impacts on Hydrology/Water Resources and Water Environment

Abstract: Though the average annual precipitation in Japan is comparatively high on a global basis, precipitation varies significantly across both time and space. In addition, a steep terrain with short rivers and narrow watersheds result in a quick runoff to the sea. The fact that this precipitation cannot be used effectively as water resources is a major distinguishing characteristic. Evaluation of warming effects based on historical weather and hydrologic records, evaluation of effects based on warming scenarios and long-term runoff model, and evaluation of effects bases on a macro- hydrological model considering atmosphere-land surface interactions have been conducted so far.