Water environment

About: Water environment is a research topic. Over the lifetime, 13384 publications have been published within this topic receiving 125138 citations.

Study of Heat Transfer Dynamics from Gold Nanorods to the Environment via Time-Resolved Infrared Spectroscopy.

Abstract: Studying the local solvent surrounding nanoparticles is important to understanding the energy exchange dynamics between the particles and their environment, and there is a need for spectroscopic methods that can dynamically probe the solvent region that is in nearby contact with the nanoparticles. In this work, we demonstrate the use of time-resolved infrared spectroscopy to track changes in a vibrational mode of local water on the time scale of hundreds of picoseconds, revealing the dynamics of heat transfer from gold nanorods to the local water environment. We applied this probe to a prototypical plasmonic photothermal system consisting of organic CTAB bilayer capped gold nanorods, as well as gold nanorods coated with varying thicknesses of inorganic mesoporous-silica. The heat transfer time constant of CTAB capped gold nanorods is about 350 ps and becomes faster with higher laser excitation power, eventually generating bubbles due to superheating in the local solvent. Silica coating of the nanorods slows down the heat transfer and suppresses the formation of superheated bubbles.

Lifting China’s Water Spell

Abstract: China is a country with significant but unevenly distributed water resources The water stressed North stays in contrast to the water abundant and polluted South defining China's current water environment In this paper we use the latest available data sets and adopt structural decomposition analysis for the years 1992 to 2007 to investigate the driving forces behind the emerging water crisis in China We employ four water indicators in China, that is, freshwater consumption, discharge of COD (chemical oxygen demand) in effluent water, cumulative COD and dilution water requirements for cumulative pollution, to investigate the driving forces behind the emerging crisis The paper finds water intensity improvements can effectively offset annual freshwater consumption and COD discharge driven by per capita GDP growth, but that it had failed to eliminate cumulative pollution in water bodies Between 1992 and 2007, 225 million tonnes of COD accumulated in Chinese water bodies, which would require 32-85 trillion m3 freshwater, depending on the water quality of the recipient water bodies to dilute pollution to a minimum reusable standard Cumulative water pollution is a key driver to pollution induced water scarcity across China In addition, urban household consumption, export of goods and services, and infrastructure investment are the main factors contributing to accumulated water pollution since 2000

Detection of three virulence genes alt, ahp and aerA in Aeromonas hydrophila and their relationship with actual virulence to zebrafish.

Abstract: Aims: To evaluate the frequency of the aerolysin (aerA), cytotoxic enterotoxin (alt) and serine protease (ahp) genes in Aeromonas hydrophila isolates from different sources, and to determine the relationship between the presence of these genes and virulence of A. hydrophila in zebrafish. Methods and Results: Aeromonas hydrophila isolates from clinical cases (n = 40), from healthy fish (n = 22) and from water environment (n = 21) were analysed with respect to the prevalence of aerA, alt and ahp genes by PCR assay. These virulence factors occur among clinical isolates as well as among isolates from healthy fish and water environment. The majority (97·6%) of the strains examined carried one or more virulence genes. The isolates were divided into seven genetic profiles on the basis of PCR result: aerA+alt+ahp+ (62·7%), aerA+alt+ahp− (13·3%), aerA+alt−ahp+ (10·8%), aerA−alt+ahp+ (4·8%), aerA−alt−ahp+ (3·6%), aerA+alt−ahp− (2·4%) and aerA−alt−ahp− (2·4%). A higher frequency of genetic group aerA+alt+ahp+ was determined in the isolates from diseased animals compared to those from healthy fish or water environments. Virulence properties of 26 representative strains belonging to the seven genetic profiles were further characterized. Results demonstrated that as the present of virulence genes increased, the proteolytic, haemolytic and cytotoxic activities of extracellular products also increased. And the 50% lethal doses (LD50s) of aerA+alt+ahp+ isolates ( 106). Conclusions: Virulence properties of A. hydrophila correlated well with the presence of virulence genes tested. aerA+alt+ahp+ was more frequent virulence genotype in A. hydrophila isolates from clinical diseases than from healthy fish and water environment, and the aerA+alt+ahp+ isolates were more virulent to zebrafish compared to the other six genetic profiles. Significant and Impact of the Study: The detection for aerA, alt and ahp can be used for virulence typing of A. hydrophila isolates.

Simulating Dye-Sensitized TiO2 Heterointerfaces in Explicit Solvent: Absorption Spectra, Energy Levels, and Dye Desorption

Abstract: Dye-sensitized solar cells (DSCs) represent a valuable, efficient, and low-cost alternative to conventional semiconductor photovoltaic devices. A deeper understanding of the dye/semiconductor heterointerface and of the dye-sensitized semiconductor/electrolyte interactions are fundamental for further progress in DSC technology. Here we report an ab initio molecular dynamics simulation of a dye-sensitized TiO2 heterointerface “immersed” in an explicit water environment for an efficient organic dye, followed by TDDFT excited state calculations of the coupled dye/semiconductor/solvent system. This new computational protocol and the extended model system allows us to gain unprecedented insight into the excited state changes occurring for the solvated dye-sensitized heterointerface at room temperature, and to provide an atomistic picture of water-mediated dye desorption.