Until recently, few water utilities or researchers were aware of possible virus presence in deep aquifers and wells. During 2008 and 2009 we collected a time series of virus samples from six deep municipal water-supply wells. The wells range in depth from approximately 220 to 300 m and draw water from a sandstone aquifer. Three of these wells draw water from beneath a regional aquitard, and thr...

We have compared the time integrated photoluminescence ~PL! and the time resolved PL of several lattice matched InGaAs/InP quantum wells intermixed either by ion implantation or an impurity-free method. We have found that the carrier capture rates into quantum wells and carrier relaxation from the wells depend on the type of intermixing used. Our results indicate that the carrier lifetimes are ...

The traditional Dutch way to deal with piping failure in river dikes is the implementation of piping berms. The disadvantage of such a measure is the required inland space. Relief wells, on the other hand, require less or no inland space representing an attractive alternative solution. The aims of this paper are first, to show how reliability analysis of relief wells systems can be carried out,...

Phosphor-free apple-white light emitting diodes have been fabricated using a dual stacked InGaN/GaN multiple quantum wells comprising of a lower set of long wavelength emitting indium-rich nanostructures incorporated in multiple quantum wells with an upper set of cyan-green emitting multiple quantum wells. The light-emitting diodes were grown on nano-epitaxially lateral overgrown GaN template f...

We evaluated the ability of UNICEF-designed pot-chlorinators to achieve recommended free residual chlorine (FRC) levels in well water in Bissau, Guinea-Bissau, during a cholera outbreak. Thirty wells were randomly selected from six neighbourhoods. Pot-chlorinators--perforated plastic bottles filled with gravel, sand and calcium hypochlorite granules--were placed in each well. FRC was measured b...

The principal mechanisms of Auger recombination of nonequilibrium carriers in semiconductor heterostructures with quantum wells are investigated. It is shown for the first time that there exist three fundamentally different Auger recombination mechanisms of (i) thresholdless, (ii) quasi-threshold, and (iii) threshold types. The rate of the thresholdless Auger process depends on temperature only...

The aim of this work was to compare, from a parasitological ( Cryptosporidium spp. and Giardia duodenalis), bacteriological (total and thermotolerants coliforms) and physicochemical perspective, water sources used for drinking and irrigation of vegetables intended to be sold for human consumption. From January 2010 to May 2011, samples of different water sources from vegetable producing propert...

Compared to vertical or lowinclination wells, horizontal wells can deliver higher production rates, higher recovery factors, and more efficient use of steam in thermally enhanced recovery projects for heavy oil. However, the shallow, thin, and friable sand reservoirs in Columbia’s Girasol field present several challenges to the accurate placement of horizontal wells. Schlumberger was contracted...

Preexisting wells and well bores are high-permeability pathways through the crust, and as such present zones of elevated risk to CO2 storage projects. Although current well closure and abandonment technology appears sufficient to contain CO2 at most sites, individual wells may suffer from a variety of factors that limit their integrity, including improper cementation, improper plugging, overpre...

There are hundreds of thousands of oil and gas wells across North America that are not currently producing oil or gas. Many of these wells have not been permanently decommissioned to meet environmental standards for permanent closure, but left in a inactive state that enables the well to be more easily reactivated. Some of the wells have been temporarily inactive for more than sixty years which...