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Results 351 - 400 of 503
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Ruan C - - 2001
A bienzyme biosensor based on tyrosinase and horse-radish peroxidase is described in a flow injection analysis and cyclic voltammetry for measurement of phenol. Tyrosinase and horse-radish peroxidase were immobilized on the surface of a glassy carbon electrode by bovine serum albumin and glutaric dialdehyde. Phenol was oxidized by tyrosinase and ...
Richards M P - - 2001
New carbon and nitrogen stable isotope values for human remains dating to the mid-Upper Paleolithic in Europe indicate significant amounts of aquatic (fish, mollusks, and/or birds) foods in some of their diets. Most of this evidence points to exploitation of inland freshwater aquatic resources in particular. By contrast, European Neandertal ...
Odake S - - 2001
The carbonation perception and sweetness perception were investigated under the presence of low level of carbondioxide less than 1.0 gas volume. Carbonation perception decreased linearly as carbonation level decreased. Sweetness perception showed inconsistency by means of evaluation methods: Triangle difference test led the result showing carbonation became a hindrance for ...
Urfer D - - 2001
A simple respirometric method was developed and applied for the measurement of biomass activity in bench-scale drinking water biofilters. The results obtained with the new method, i.e. biomass respiration potential (BRP), indicated a high sensitivity allowing the quantification of the activity of low amounts of biomass. The analysis of duplicate ...
Niazi J H - - 2001
Dimethylphthalate (DMP), one of the phthalate esters, is used in the manufacture of plasticizers, insect repellents, and synthetic fibers, and contributes to environmental pollution. In the present study, we report a novel bacterium belonging to the Bacillus sp., which has the ability to utilize DMP as the sole source of ...
Mukai H - - 2001
Sulfur and lead isotope ratios in the atmosphere were measured at several selected sites (Harbin, Changchun, Dalian, Waliguan, Shanghai, Nanjing, Guiyang) in China and Tsukuba (Japan), to reveal regional sources characteristics over Eastern Asia. Average S isotope ratios for SO2 and sulfate in the atmosphere in China were close to ...
Wen X L - - 2001
The electrochemistry of L-tyrosine was studied by cyclic voltammetry at a glassy carbon electrode. Although L-tyrosine itself showed very poor electrochemical response, the response could be greatly enhanced by using 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy (HO-TEMPO) as a mediator that enables a sensitive determination of the substrate. An electrocatalytic EC' mechanism with the oxoammonium ...
Ahn D J - - 2001
Controlled environments (CE) in which light, carbon dioxide, and nutrients are regulated are known to affect the chemical composition of plants. Controlled Ecological Life Support System (CELSS) environments are required for a Mars or lunar base where food resupply is both impractical and risky. Astronauts in a CELSS would need ...
Knoff A J - - 2001
Food web studies often ignore details of temporal, spatial, and intrapopulation dietary variation in top-level consumers. In this study, intrapopulation dietary variation of a dominant carnivore, the Laughing Gull (Larus atricilla), was examined using carbon, nitrogen, and sulfur isotope analysis of gull tissues as well as their prey (fish, invertebrates, ...
Okamoto T - - 2001
Previously we reported carbon tetrachloride-induced body weight loss in rats as a new model of wasting disorders. The oral administration of a low dose of carbon tetrachloride to rats reduced the body weight and food intake at 24 h with a minimal effect on plasma alanine aminotransferase activity. Tumor necrosis ...
Gasperini D - - 2000
Up to 10 per cent of the ocean floor consists of plateaux--regions of unusually thick oceanic crust thought to be formed by the heads of mantle plumes. Given the ubiquitous presence of recycled oceanic crust in the mantle source of hotspot basalts, it follows that plateau material should also be ...
Bousquet P - - 2000
We have applied an inverse model to 20 years of atmospheric carbon dioxide measurements to infer yearly changes in the regional carbon balance of oceans and continents. The model indicates that global terrestrial carbon fluxes were approximately twice as variable as ocean fluxes between 1980 and 1998. Tropical land ecosystems ...
Spencer K - - 2000
Variations measured in the lead (Pb) stable isotope ratios in otoliths of juvenile tropical reef fish Scarus perspiculatus, Abudefduf abdominalis and Dascyllus albisella reflect mixing of anthropogenic lead from the Kaneohe Bay watershed and 'background' lead characteristic of the adjacent ocean. The otoliths and water samples collected in a transect ...
Pierce S - - 2000
Many biotypes of the northern-hemisphere Arctic-Alpine grass Poa alpina L. reproduce asexually via prolification of the spikelet axis to produce dehiscing shoots. Although capable of photosynthesis, the source-sink characteristics of these synflorescence systems are unknown, including the degree to which plantlets from different regions of the synflorescence are capable of ...
Roditi H A - - 2000
Zebra mussels (Dreissena polymorpha) are widespread and abundant in major freshwater ecosystems in North America, even though the phytoplankton food resources in some of these systems seem to be too low to sustain them. Because phytoplankton biomass is greatly depleted in ecosystems with large D. polymorpha populations and bacteria do ...
Hu J Z - - 2000
It is shown in this paper that a previously reported 90 degrees sample flipping (13)C 2D CSA-CSA correlation experiment may be carried out alternatively by employing constant slow sample rotation about the magic angle axis and by synchronizing the read pulse to 13 of the rotor cycle. A high-resolution 3D ...
Médina B - - 2000
Over the last century, the atmospheric fallout of anthropogenic lead has evolved with time, as a function of the chronological variability of transient lead inputs from both industrial and gasoline origins. This variability has been mostly documented over North America and northern Europe. In this study we used ICP-MS for ...
Messenger S - - 2000
Interplanetary dust particles (IDPs) collected in the Earth's stratosphere and meteorites are fragments of comets and asteroids. These are 'primitive' meteorites in part because they have preserved materials which predate the formation of the Solar System. The most primitive (least altered) meteorites contain a few parts per million of micrometre-sized ...
Pin C - - 2000
A quadratic response surface model is presented to describe the maximum specific growth rate of Yersinia enterocolitica, at refrigeration temperatures, under modified atmospheres. The presence of CO2 affected mainly the lag phase of the organism. The length of the lag phase increased with higher levels of CO2 in the atmosphere, ...
Schmidt, I K
Nutrient availability is a major constraint to plant production and carbon storage in arctic ecosystems, but there are few studies coupling processes in the decomposer and microbial food web and the implications these processes have on the control of nutrient mineralization. We studied the relationship between microbial biomass and the ...
Meyer H - - 2000
Equilibration technique suitable for a large amount of samples is described for hydrogen and oxygen isotope analyses of ground ice, especially ice wedges, including the sampling strategy and the analytical procedure as well as the calibration of the Finnigan MAT Delta-S mass spectrometer in June, 1999. Since for future analyses ...
Spiro B - - 2000
The numerous stable isotope studies of scleractinian photosynthetic reef-building corals in tropical seas have demonstrated the complexity of the biological and environmental factors that give rise to their isotopic composition. Scleractinian non-photosynthetic corals of the deep cold water environment might be expected to reflect the more stable physical environment in ...
Morrison D J - - 2000
Surprisingly little information is available on the natural abundance of the minor isotope of carbon, (13)C, in common foodstuffs in the British diet. This study therefore aimed to examine the (13)C natural abundance of foodstuffs from a small cross-section of the British diet. The isotopic abundance, delta per mil, was ...
Chung H H - - 2000
In this study, the effects of carbon sources and various levels of sucrose (0-30%) yeast extract (0-1.25%) and phenylalanine (0-0.2%) on the production of 2-phenylethanol by Pichia fermentans L-5 were investigated. Results revealed that among the 11 carbon sources tested, glycerol and sucrose were suitable carbon sources for P. fermentans ...
Verma D K - - 1999
Methods of assessing occupational exposure to diesel exhaust were evaluated in a railroad work environment. The American Conference of Governmental Industrial Hygienists (ACGIH)-recommended elemental carbon and respirable combustible dust methods of sampling and analysis for assessing diesel exhaust were included in the study. A total of 215 personal and area ...
Smith H J - - 1999
The most conspicuous feature of the record of past climate contained in polar ice is the rapid warming which occurs after long intervals of gradual cooling. During the last four transitions from glacial to interglacial conditions, over which such abrupt warmings occur, ice records indicate that the CO2 concentration of ...
Gold D - - 1999
Approximately 400 indigenous divers live and work on Thailand's west coast. They dive with surface supplied air from primitive compressor units mounted on open boats which measure from seven to 11 meters in length. It was suspected that carbon monoxide was present in the breathing air of at least the ...
Overmann J - - 1999
A meromictic lake ecosystem (Mahoney Lake, BC, Canada) was investigated to elucidate the significance of chemocline bacteria in the total carbon cycle under natural conditions. In this lake, primary production by oxygenic phototrophs was insufficient to support the observed net secondary production of the calanoid copepod Diaptomus connexus and the ...
Hallock G G - - 1999
Laserbrasion is essentially skin deepithelialization. The continuous-wave carbon dioxide (CO2) laser has a long history during which this capability to ablate the epidermis has been used in multiple clinical applications. The "improved" UltraPulse CO2 laser has been advocated as a safer method, primarily for skin resurfacing. The authors show in ...
Socolow R H - - 1999
The food system dominates anthropogenic disruption of the nitrogen cycle by generating excess fixed nitrogen. Excess fixed nitrogen, in various guises, augments the greenhouse effect, diminishes stratospheric ozone, promotes smog, contaminates drinking water, acidifies rain, eutrophies bays and estuaries, and stresses ecosystems. Yet, to date, regulatory efforts to limit these ...
Pelegrí SP - - 1999
> Abstract We established a budget of organic carbon utilization of a starved heterotrophic nanoflagellate, Pteridomonas danica, incubated in batch cultures with Escherichia coli as model prey. The cultures were sampled periodically for biomass determinations and total organic carbon dynamics: total organic carbon, total organic carbon <1 µm, and dissolved ...
Huang W H - - 1999
Four food grade additives-sodium ascorbate, sodium bicarbonate, sodium carbonate-10-hydrate, and ferrous sulfate-7-hydrate-were selected as the basic ingredients to formulate the controlled atmosphere agents which could effectively remove oxygen and release carbon dioxide. The mathematical models giving the relationships between the formulations and the responses (oxygen and carbon dioxide contents) were ...
Maiti H - - 1999
Cryotherapy is regularly used in our clinic for treating genital warts. Nitrous oxide was used as the cryogenic gas. Following a health and safety review it was decided to monitor the nitrous oxide levels in the treatment room under different conditions. The Occupational Exposure Standard for nitrous oxide is 100 ...
Sponheimer M - - 1999
Current consensus holds that the 3-million-year-old hominid Australopithecus africanus subsisted on fruits and leaves, much as the modern chimpanzee does. Stable carbon isotope analysis of A. africanus from Makapansgat Limeworks, South Africa, demonstrates that this early hominid ate not only fruits and leaves but also large quantities of carbon-13-enriched foods ...
Bohnert M - - 1999
Under low ambient temperatures normally bluish postmortem lividity adopts a bright red or pink colour due to resaturation of haemoglobin with O2. The most important differential diagnosis in the presence of pink hypostasis is carbon monoxide poisoning. To answer the question if objective measuring methods allow differentiation of hypostasis with ...
Garrett M H - - 1999
Indoor nitrogen dioxide exposure has been associated with respiratory symptoms in children in many studies, but in Australia, levels and sources of nitrogen dioxide in homes have not been well-characterized. Therefore, as part of a larger indoor environmental study, conducted in the Latrobe Valley, Victoria, nitrogen dioxide was monitored using ...
Verma D K - - 1999
This article (the second of a two-part series) provides a discussion of currently accepted methodology and possible future happenings regarding measurement of benzene in workplaces. The gap between occupational and environmental monitoring is becoming narrow. Environmental levels will always be lower than the occupational, but as the push for lower ...
Morales M - - 1998
Biotechnological techniques, including biofilters and biotrickling filters are increasingly used to treat air polluted with VOCs (Volatile Organic Compounds). In this work, the start-up, the effect of the gaseous ammonia addition on the toluene removal rate, and the problems of the heat accumulation on the performance of a laboratory scale ...
Siniak I E - - 1998
Differences in the isotope content of the biogenous chemicals of cosmonaut habitats are given a theoretical consideration. Rationale is given to the hypothesis according to which the biochemical and biophysical processes in plants. animals, and humans must be impacted by the isotopes of all the biogenous chemicals in cosmonaut habitats. ...
Mittendorfer B - - 1998
We have used a 3-h primed continuous infusion of [1,2-13C]acetate in five fasted (24 h) volunteers to quantify splanchnic and leg acetate metabolism (protocol 1). Fractional extraction of acetate by both tissues was high ( approximately 70%), and simultaneous uptake and release of acetate were observed. Labeled carbon recovery in ...
Chisholm J R - - 1998
It is not certain whether coral reefs are sources of or sinks for atmospheric CO2. Air-sea exchange of CO2 over reefs has been measured directly and inferred from changes in the seawater carbonate equilibrium. Such measurements have provided conflicting results. We provide community metabolic data that indicate that large changes ...
Zen J M - - 1998
A Nafion-ruthenium oxide pyrochlore chemically modified electrode is used for the determination of caffeine in beverages by square-wave voltammetry. Compared to a bare glassy carbon electrode, the chemically modified electrode exhibits a marked enhancement of the current response. A linear calibration curve is obtained over the 5-200 microns range in ...
Wright L E - - 1998
This paper investigates the utility of stable carbon and oxygen isotopes in human dental enamel to reveal patterns of breastfeeding and weaning in prehistory. Enamel preserves a record of childhood diet that can be studied in adult skeletons. Comparing different teeth, we used delta13C to document the introduction of solid ...
Sweeney C T - - 1998
Effect of vent blocking on carbon monoxide (CO) exposure from a best-selling light cigarette was examined in 12 daily cigarette smokers. Mean CO boosts were not different from each other with (a) 0% filter vents blocked (5.0 ppm), (b) vents covered with lips (4.9 ppm), (c) 50% of vents covered ...
Haasum I - - 1998
The combined effects of pH, water activity (aw), oxygen (O2) and carbon dioxide (CO2) levels on growth and sporulation of 10 common food-borne fungi were studied. The use of a multivariate statistical method (PLS) for the analysis of data showed that the fungi could be grouped according to their physiological ...
Bozelli, Reinaldo Luiz
Bauxite processing in Porto Trombetas, Brazil, generated a fine particulate effluent that was dumped into Lake Batata over a ten-year period, leading to high suspended solids, reduced water transparency and increased turbidity in parts of the lake. The influence of bauxite tailings on cladoceran feeding was studied by measuring carbon ...
Schulze E - - 1998
Naturally produced methane shows different delta 13C-values with respect to its origin, e.g., geological or biological. Methane-production of ruminants is considered to be the dominant source from the animal kingdom. Isotopic values of rumen methane--given in literature--range between -80/1000 and -50/1000 and are related to feed composition and also sampling ...
Okamoto M - - 1998
A full-automated hyperbaric environmental control system (HECS) for nitrox saturation diving HABITAT has been examined since 1994. HECS was planned to be located inside HABITAT and operated automatically by supplying electricity and cooling water. To realize this, a regenerative-type carbon dioxide removal method and AC 100 V electric powered blower ...
Boag B - - 1998
We report the first isotopic study of an animal host-parasite system. Parasitic, intestinal nematodes, Graphidium strigosum and Passalurus ambiguus, were 15N-enriched relative to their host, the European rabbit Oryctolagus cuniculus, while parasitic cestodes, Cittataenia denticulata and Mosgovoyia pectinata, were 15N-depleted, suggesting different trophic relationships. Host embryos were more similar in ...
Ambrose S H - - 1997
Proportions of marine vs. terrestrial resources in prehistoric human diets in the southern Mariana Islands (Guam, Rota, Saipan), Micronesia, have been estimated by analysis of stable isotope ratios of carbon and nitrogen in bone collagen and of carbon in apatite. The isotopic composition of marine and terrestrial food resources from ...
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