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Acidic Water (acidic + water)
Selected AbstractsFreshwater crayfish farming technology in the 1990s: a European and global perspectiveFISH AND FISHERIES, Issue 4 2000H.E.G. Ackefors This paper aims to describe the state of crayfish farming technology in the USA, Australia and Europe, and to discuss some of the prerequisites for this industry. Data from Europe are partly based on replies from a questionnaire sent out to scientists in all European countries. For other parts of the world, the crayfish literature has been reviewed and data from the August 2000 meeting of the International Association of Astacology are also included. Issues addressed in this review are cultivated species, production and productivity figures, production technique with regard to enclosures, reproduction and feed items, disease problems, predators, pond vegetation and water quality. Fewer than a dozen crayfish species are cultivated. The most attractive ones for culture and stocking in natural waters have been transferred to more than one continent. Pond rearing techniques predominate in all countries, and the technology required to achieve the spawning and rearing of juveniles is relatively simple. Pieces of fish, carrots and potatoes are frequent supplementary feed items; plants, cereals, pieces of meat, zooplankton and pellets are also common. Diseases are not usually a major concern, except in Europe where the American plague fungus, Aphanomyces astaci, has eradicated many European crayfish populations. Predators identified as common include insects and amphibians, as well as fishes, birds and mammals. Many water macrophytes are common in crayfish farms. These may either serve a useful function or cause problems for the crayfish farmer. Water temperature is the crucial factor for crayfish production. Water parameters such as pH and certain inorganic ion concentrations may also be of concern. Acidic waters that occur in some areas are generally detrimental to crayfish. The total yield from crayfish production from farming and fishery is in the order of 120 000,150 000 tonnes, more than four times the quantity given by FAO statistics. The largest crayfish producer is the Peoples' Republic of China, followed by the USA (70 000 and 50 000 tonnes in 1999, respectively). Of the quantity produced in the USA in 1999, about 35 000 tonnes was farmed. The yield in Europe was about 4500 tonnes in 1994, and of this quantity only 160 tonnes came from aquaculture. There are no official statistics for crayfish fishery production in Australia, but about 400 tonnes came from aquaculture in 1999. [source] Geckos as indicators of mining pollutionENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2006Dean E. Fletcher Abstract Catastrophic collapse of a mine tailings dam released several million cubic meters of toxic mud and acidic water into the Guadiamar River valley, southern Spain, in 1998. Remediation efforts removed most of the sludge from the floodplain, but contamination persists. Clean-up activities also produced clouds of aerosolized materials that further contaminated the surrounding landscape. Whole-body concentrations of 21 elements in the Moorish wall gecko, Tarentola mauritanica, a common inhabitant of both rural and urban areas, were compared among seven locations. Locations spanned an expected contamination gradient and included a rural and an urban non,mine-affected location, two mine-affected towns, and three locations on the contaminated floodplain. Multivariate analyses of whole-body concentrations identified pollutants that increased across the expected contamination gradient, a trend particularly evident for As, Pb, and Cd. Additionally, higher contaminant concentrations occurred in prey items eaten by geckos from mine-affected areas. Comparison of element concentrations in tails and whole bodies suggests that tail clips are a viable nondestructive index of contaminant accumulation. Our results indicate that areas polluted by the mine continue to experience contamination of the terrestrial food chain. Where abundant, geckos represent useful taxa to study the bioavailability of some hazardous pollutants. [source] Growth and population size of crayfish in headwater streams: individual- and higher-level consequences of acidificationFRESHWATER BIOLOGY, Issue 7 2004Steven M. Seiler Summary 1. Environmental stress may have indirect positive effects on population size through modification of food-web interactions, despite having negative effects on individuals. Here we evaluate the individual- and population-level effects of acidification on crayfish (Cambarus bartonii) in headwater streams of the Allegheny Plateau (PA, U.S.A.) with field experiments and survey data. Median baseflow pH of 24 study reaches in nine streams varied from 4.4 to 7.4, with substantial variation found both among and within streams. 2. Two bioassays were conducted to evaluate the relationship between stream pH and crayfish growth rates. Growth rates were always higher in circumneutral reaches than in acidic reaches. Crayfish originating in acidic water grew less when transplanted into neutral water than did crayfish originating in neutral water, providing some evidence for a cost of acclimation to acidity. 3. Stream surveys showed that fish were less abundant and crayfish more abundant in acidified streams than in circumneutral streams. Crayfish density was sixfold higher in reaches with the lowest pH relative to circumneutral reaches. Large crayfish made up a higher proportion of crayfish populations at sites with high fish biomass, consistent with the hypothesis that fish predation on small individuals may be limiting crayfish population size at these sites. 4. Although individual crayfish suffered lower growth in acidified streams, increased acidity appeared to cause an increase in crayfish population size and shifts in size structure, possibly by relieving predation pressure by fish. [source] Tuning Carbon Materials for Supercapacitors by Direct Pyrolysis of SeaweedsADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Encarnación Raymundo-Piñero Abstract The sea provides a large variety of seaweeds that, because of their chemical composition, are fantastic precursors of nanotextured carbons. The carbons are obtained by the simple pyrolysis of the seaweeds under a nitrogen atmosphere between 600 and 900,°C, followed by rinsing the product in slightly acidic water. Depending on the origin of the seaweed and on the pyrolysis conditions, the synthesis may be oriented to give an oxygen-enriched carbon or to give a tuned micro/mesoporous carbon. The samples with a rich oxygenated surface functionality are excellent as supercapacitor electrodes in an aqueous medium whereas the perfectly tuned porous carbons are directly applicable for organic media. In both cases, the specific surface area of the attained carbons does not exceed 1300 m2 g,1, which results in high-density materials. As a consequence, the volumetric capacitance is very high, making these materials more interesting than activated carbons from the point of view of developing small and compact electric power sources. Such versatile carbons, obtained by a simple, ecological, and cheap process, could be well used for environment remediation such as water and air treatment. [source] Application of the transformed Potts,Guy equation to in vivo human skin dataJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2001William J. Roberts Abstract Data developed by Wenkers and Lippold for the flux of 10 nonsteroidal anti-inflammatory drugs from light mineral oil (MO) through human skin in vivo has been analyzed using the transformed Potts,Guy equation. The analysis shows that the flux is dependent not only on the solubility in MO (SMO), but also on the solubility in acidic water (SAQ). This dependence of flux on SAQ shows that the previously reported dependence of flux on SAQ from in vitro experiments using hairless mouse skin is not an artifact of the in vitro experiments but is due to a characteristic of the skin barrier. Further inspection of the equations used by Wenkers and Lippold in their analyses of their data shows that the equations are variations of the transformed Potts,Guy equation. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1318,1323, 2001 [source] Proteomic analysis of the response of an acidophilic strain of Chlamydomonas sp. (Chlorophyta) to natural metal-rich waterPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 10 2010Cristina Cid Abstract A proteomic approach including 2-DE and MALDI-TOF analysis has been developed to identify the soluble proteins of the unicellular photosynthetic algae Chlamydomonas sp. isolated from an extreme acidic environment, Río Tinto (southwest Spain). We have analyzed the soluble proteome obtained from whole cells growing on metal-rich natural acidic water from the river in comparison with the same strain growing in artificial BG-11 media. The most drastic effect was the decrease in the abundance of the ribulose-1,5-biphosphate carboxylase as well as other enzymes related to photosynthesis. However, phytochrome B, phosphoribulokinase, and phosphoglycerate kinase were upregulated when cells were grown in metal-rich acidic water. Besides, increased accumulation of two Hsps, Hsp70 and Hsp90 as well as other stress-related enzymes were also found in the cells growing in natural acidic water. These results suggest that naturally occurring metal-rich water induces a stress response in acidophilic Chlamydomonas forcing algal cells to reorganize their metabolic pathways as an adaptive response to these environmental conditions. [source] Highly Active and Removable Ruthenium Catalysts for Transition-Metal-Catalyzed Living Radical Polymerization: Design of Ligands and CocatalystsCHEMISTRY - AN ASIAN JOURNAL, Issue 8-9 2008Makoto Ouchi Dr. Abstract The systematic search and design of phosphine ligands (PR3) and amine cocatalysts resulted in obtaining pentamethyl-cyclopentadienyl (Cp*) ruthenium(II) phosphine complexes [RuCp*Cl(PR3)2], which are highly active and removable catalysts, for transition-metal-catalyzed living radical polymerization of methyl methacrylate (MMA). The catalysts are conveniently prepared in situ from a tetrameric precursor [RuCp*(,3 -Cl)]4 and a selected phosphine (PR3). The combination of the meta -tolyl phosphine [P(m -Tol)3] ligand and a primary diamine cocatalyst [NH2(CH2)6NH2] provides a highly active catalytic system with precision control of the molecular weight of the polymer. The high activity enables a low catalyst dose and a high turn-over frequency without deteriorating the controllability. A hydrophilic amine cocatalyst (amino alcohol) in place of the diamine, further forms an active and removable catalyst; simple treatment with acidic water gave colorless polymers visually free from metal residues (>97,% removal; <64,ppm). [source] Chiral Induction, Memory, and Amplification in Porphyrin Homoaggregates Based on Electrostatic InteractionsCHEMPHYSCHEM, Issue 6 2009LiXi Zeng Dr. Abstract Supramolecular chirality in two configurational homoaggregates of anionic meso -tetrakis(4-sulfonatophenyl)porphyrin (TPPS) can be induced by D - and L -alanine in acidic water (see picture). The chirality can be further memorized and enforced through strong electrostatic interactions between TPPS aggregates and achiral poly(allylamine) [PAA]. Supramolecular chirality in two configurational homoaggregates of anionic meso -tetrakis(4-sulfonatophenyl)porphyrin (TPPS) can be induced by D - and L -alanine (Ala) in acidic water, respectively. The induced supramolecular chirality can be further memorized and enforced, even after complete removal of Ala or in the presence of excess Ala with the opposite configuration, through strong electrostatic interactions with achiral poly(allylamine) [PAA]. The ionic chiral interactions between TPPS and Ala or PAA are characterized by means of UV/Vis absorption and circular dichroism spectrometry. Fluorescence spectroscopy and atomic force microscopy are used as complementary techniques. On the basis of the comprehensive experimental results, a possible mechanism for chiral induction, memory, and amplification of TPPS homoaggregates by chiral amino acids and achiral PAA is proposed. Thus, we demonstrate a novel strategy to realize chiral memory in supramolecular systems by polyelectrolytes through hierarchical electrostatic self-assembly. [source] From Cloudy to Transparent: Chain Rearrangement in Hydrogen-Bonded Layer-by-Layer Assembled FilmsCHEMPHYSCHEM, Issue 3 2007Shuguang Yang Abstract The cloudiness of hydrogen-bonded LBL films assembled from polyvinylpyrrolidone (PVPON) and poly(acrylic acid) (PAA) is studied in detail by two approaches: spectroscopy (Fabry,Pérot fringes) and microscopy (AFM). Fabrication parameters such as temperature, molecular weight, pH value, and rinsing time, have notable influences on film cloudiness. The buildup of the PVPON/PAA film is a two-stage process of adsorption and chain rearrangement. Generally, adsorption is fast, while chain rearrangement is slow. The fast adsorption process traps defects, whereas the relatively slow chain-rearrangement process can not heal the defects in time; therefore, the number of defects continuously increases as LBL assembly proceeds, and a cloudy, heterogeneous film is produced. However, the as-prepared cloudy films become transparent and homogeneous on subsequent annealing in acidic water. UV/Vis spectroscopy and fluid AFM were applied to monitor this transition ex situ and in situ, respectively. It is found that increasing the annealing temperature accelerates the transition from cloudy to transparent, and the transition of the film made from higher molecular weight polymer is slower. [source] | |||||||||||||