Cold crucible Czochralski for solar cells

The efficiency and radiation resistance of present silicon solar cells are a function of the oxygen and carbon impurities and the boron doping used to provide the proper resistivity material. The standard Czochralski process used grow single crystal silicon contaminates the silicon stock material due to the use of a quartz crucible and graphite components. The use of a process which replaces these elements with a water cooled copper to crucible has provided a major step in providing gallium doped (100) crystal orientation, low oxygen, low carbon, silicon. A discussion of the Cold Crucible Czochralski process and recent float Zone developments is provided

Pharmaceutical and personal care products-induced stress symptoms and detoxification mechanisms in cucumber plants.

Contamination of agricultural soils by pharmaceutical and personal care products (PPCPs) resulting from the application of treated wastewater, biosolids and animal wastes constitutes a potential environmental risk in many countries. To date a handful of studies have considered the phytotoxicity of individual PPCPs in crop plants, however, little is known about the effect of PPCPs as mixtures at environmentally relevant levels. This study investigated the uptake and transport, physiological responses and detoxification of a mixture of 17 PPCPs in cucumber seedlings. All PPCPs were detected at higher concentrations in roots compared to leaves, with root activity inhibited in a dose-dependent manner. At 5-50 μg/L, the mature leaves exhibited burnt edges as well as a reduction in photosynthesis pigments. Reactive oxygen species (ROS) production and lipid peroxidation increased with increasing PPCP concentrations; and their contents were greater in roots than in leaves for all PPCP treatments. Enzymes involved in various functions, including oxidative stress (superoxide dismutase and ascorbate peroxidase) and xenobiotic metabolism (peroxidase and glutathione S-transferase), were elevated to different levels depending on the PPCP concentration. Glutathione content gradually increased in leaves, while a maxima occurred at 0.5 μg L-1 PPCPs in roots, followed by a decrease thereafter. This study illustrated the complexity of phytotoxicity after exposure to PPCP mixtures, and provided insights into the molecular mechanisms likely responsible for the detoxification of PPCPs in higher plants

Testing of gallium arsenide solar cells on the CRRES vehicle

A flight experiment was designed to determine the optimum design for gallium arsenide (GaAs) solar cell panels in a radiation environment. Elements of the experiment design include, different coverglass material and thicknesses, welded and soldered interconnects, different solar cell efficiencies, different solar cell types, and measurement of annealing properties. This experiment is scheduled to fly on the Combined Release and Radiation Effects Satellite (CRRES). This satellite will simultaneously measure the radiation environment and provide engineering data on solar cell degradation that can be directly related to radiation damage

Explaining the President's Executive Actions on Guns

President Obama recently announced a package of executive actions intended to reduce gunviolence and make our communities safer. In a nation where 33,000 Americans die by gun everyyear, these common sense regulations seek to give teeth to our existing gun laws, some of whichhave been nearly impossible to enforce as written. Though these actions include more than adozen components, including increased funding for mental health treatment, the addition of morelaw enforcement agents and background check examiners, and the foundation of an InternetInvestigations Center to track online gun trafficking, four are particularly likely to raise the ire of theNational Rifle Association (NRA) and its allies. This memo breaks down each: examining the flawsin our current enforcement system and explaining how these actions remedy them

Trophic Transfer of Arsenic from an Aquatic Insect to Terrestrial Insect Predators.

The movement of energy and nutrients from aquatic to terrestrial ecosystems can be substantial, and emergent aquatic insects can serve as biovectors not only for nutrients, but also for contaminants present in the aquatic environment. The terrestrial predators Tenodera aridifolia sinensis (Mantodea: Mantidae) and Tidarren haemorrhoidale (Araneae: Theridiidae) and the aquatic predator Buenoa scimitra (Hemiptera: Notonectidae) were chosen to evaluate the efficacy of arsenic transfer between aquatic and terrestrial environments. Culex tarsalis larvae were reared in either control water or water containing 1000 µg l(-1) arsenic. Adults that emerged from the control and arsenic treatments were fed to the terrestrial predators, and fourth instar larvae were fed to the aquatic predator reared in control or arsenic contaminated water. Tenodera a. sinensis fed arsenic-treated Cx. tarsalis accumulated 658±130 ng g(-1) of arsenic. There was no significant difference between control and arsenic-fed T. haemorrhoidale (range 142-290 ng g(-1)). Buenoa scimitra accumulated 5120±406 ng g(-1) of arsenic when exposed to arsenic-fed Cx. tarsalis and reared in water containing 1000 µg l(-1) arsenic. There was no significant difference between controls or arsenic-fed B. scimitra that were not exposed to water-borne arsenic, indicating that for this species environmental exposure was more important in accumulation than strictly dietary arsenic. These results indicate that transfer to terrestrial predators may play an important role in arsenic cycling, which would be particularly true during periods of mass emergence of potential insect biovectors. Trophic transfer within the aquatic environment may still occur with secondary predation, or in predators with different feeding strategies

Effects of High-Level Acylsugar-Producing Tomato Lines on the Development of Tomato Psyllids (Hemiptera: Triozidae).

Acylsugars have been shown to provide activity against numerous insect pests of tomatoes. Comparison of acylsugar levels in four tomato plant lines, FA7/AS, FA2/AS, CU071026, and 'Yellow Pear', found that the acylsugar contents in the elevated acylsugar lines were significantly higher than the commercial Yellow Pear (control) tomato plant line. Adult choice tests indicated that the tomato psyllid, Bactericera cockerelli, preferred to settle on the Yellow Pear and FA2/AS lines over the line with the highest content of acylsugars, FA7/AS, and the parental line, CU071026. The no-choice test demonstrated that adults laid fewer eggs on the high acylsugar tomato lines than on the control tomato line, Yellow Pear. For all high acylsugar lines, the relative growth index of the psyllid was significantly lower compared with the commercial line, indicating a reduced potential for population growth. Although some tomato psyllids completed their life cycle on the high acylsugar tomato plant lines, the percent survival of psyllids to the adult stage when developing on the high acylsugar lines was significantly less (range = 43.7-57.1%) than on the commercial tomato line (83.8%). All mortality occurred during the early stages of development (egg stage to third instar), which has implications for acquisition and transmission of Candidatus Liberibacter solanacearum, the causal agent of tomato vein greening disease. Therefore, with reduced attractiveness for tomato psyllids and significantly reduced survival, the high-acylsugar tomato plant lines have the potential to be part of an integrated pest management program for this pest

Formation of biologically active benzodiazepine metabolites in Arabidopsis thaliana cell cultures and vegetable plants under hydroponic conditions.

The use of recycled water for agricultural irrigation comes with the concern of exposure to crops by contaminants of emerging concerns (CECs). The concentration of CECs in plant tissues will depend on uptake, translocation and metabolism in plants. However, relatively little is known about plant metabolism of CECs, particularly under chronic exposure conditions. In this study, metabolism of the pharmaceutical diazepam was investigated in Arabidopsis thaliana cells and cucumber (Cucumis sativus) and radish (Raphanus sativus) seedlings grown in hydroponic solution following acute (7 d)/high concentration (1 mg L-1), and chronic (28 d)/low concentration (1 μg L-1) exposures. Liquid chromatography paired with mass spectrometry, 14C tracing, and enzyme extractions, were used to characterize the metabolic phases. The three major metabolites of diazepam - nordiazepam, temazepam and oxazepam - were detected as Phase I metabolites, with the longevity corresponding to that of human metabolism. Nordiazepam was the most prevalent metabolite at the end of the 5 d incubation in A. thaliana cells and 7 d, 28 d seedling cultivations. At the end of 7 d cultivation, non-extractable residues (Phase III) in radish and cucumber seedlings accounted for 14% and 33% of the added 14C-diazepam, respectively. By the end of 28 d incubation, the non-extractable radioactivity fraction further increased to 47% and 61%, indicating Phase III metabolism as an important destination for diazepam. Significant changes to glycosyltransferase activity were detected in both cucumber and radish seedlings exposed to diazepam. Findings of this study highlight the need to consider the formation of bioactive transformation intermediates and different phases of metabolism to achieve a comprehensive understanding of risks of CECs in agroecosystems