Fair Water Use
Two methods for the detection of important human pathogens, Cryptosporidium parvum and Helicobacter pylori, were investigated: a fiber optic biosensor, and real time PCR. The mechanism for specific detection in both methods is recognition of specific DNA sequences in the target organisms. The biosensor that was used, the Analyte 2000, was originally developed for the detection of chemicals. It utilizes a fiber optic wave guide that propagates an evanescent light wave of very specific wavelength. The light excites fluorescent molecules bound to the waveguide, but not in the bulk solution, which theoretically enhances signal while reducing background interference. Attempts to develop this system for the detection of DNA were not successful due to poor detection of the target molecules. An assay analogous to a sandwich immunoassay was designed for use on the Analyte 2000. Specific oligonucleotide probes were designed to bind to the waveguides via biotin-streptavidin interaction, and were used to capture the target DNA. Pure target DNA representing unique genes in the organisms were synthesized by PCR. Detection of captured DNA was then attempted using an oligonucleotide detection probe designed to bind to the target. Two detection systems were employed: an indirect signal amplification system based on biotin-tyramide deposition, or direct detection of fluorescent signal from Cy-5 molecules. In all experiments performed there was very little difference between the signal generated with or without the target molecules. Many experiments were conducted to attempt to identify reasons for the poor signal. Signal was only of any significance when target amplicons were internally labeled with Cy-5 by PCR. Real time PCR as a method to detect the pathogens was also investigated. Though the PCR technique itself is very rapid, DNA extraction and purification requires preparation time. Filtration of up to one liter of well water, followed by concentration and "cleaning" Helicobacter pylori cells by immunomagnetic separation, was used to detect H. pylori seeded in a water source. Following cell lysis, the extracted DNA could be used directly in conventional PCR targeting the 16S rRNA gene to detect less than 265 cells per liter of water. DNA purification was not required for this level of detection. Initial studies to amplify lysed cells by real time PCR indicated that an incorrect product was made. When purified DNA was used for real time PCR, the correct product was produced from DNA representing as few as 100 cells. This publication can be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below
Laser processing of solid materials has been commonly performed in gas ambient. Having the workpiece immersed into liquid, having a liquid film on it, or soaking the material with liquid gives several advantages such as removal of the debris, lowering the heat load on the workpiece, and confining the vapour and plasma, resulting in higher shock pressure on the surface.
The fine estuary which penetrates the American coast, between the fortieth and forty-first degrees of latitude, is formed by the confluence of the Hudson, the Hackensack, the Passaic, the Raritan, and a multitude of smaller streams; all of which pour their tribute into the ocean, within the space named. The islands of Nassau and Staten are happily placed to exclude the tempests of the open sea, while the deep and broad arms of the latter offer every desirable facility for foreign trade and internal intercourse. To this fortunate disposition of land and water, with a temperate climate, a central position, and an immense interior, that is now penetrated, in every direction, either by artificial or by natural streams, the city of New-York is indebted for its extraordinary prosperity. Though not wanting in beauty, there are many bays that surpass this in the charms of scenery; but it may be questioned if the world possesses another site that unites so many natural advantages for the growth and support of a widely extended commerce. As if never wearied with her kindness, Nature has placed the island of Manhattan at the precise point that is most desirable for the position of a town. Millions might inhabit the spot, and yet a ship should load near every door; and while the surface of the land just possesses the inequalities that are required for health and cleanliness, its bosom is filled with the material most needed in construction.
The 21-Day Clean Eating Challenge, the tenth book in the 21-Day Challenge series!
Water-Resources Engineering provides comprehensive coverage of hydraulics, hydrology, and water-resources planning and management. Presented from first principles, the material is rigorous, relevant to the practice of water resources engineering, and reinforced by detailed presentations of design applications. Prior knowledge of fluid mechanics and calculus (up to differential equations) is assumed.
Fair Water Use Articles
Fair Water Use Books
Fair Water Use