Process controls introduction of selected impurities into semiconductor wafers

Modified three-step process controls the concentration of lithium diffused as a dopant into the base region of a diffused n-on-p silicon solar cell wafer. Part of the surface layer of the base region of the p-type silicon containing the diffused dopant is removed, prior to redistributing the remaining portion of the dopant into the bulk of the wafer

Ecological Niche Modeling of Potential West Nile Virus Vector Mosquito Species in Iowa

Ecological niche modeling (ENM) algorithms, Maximum Entropy Species Distribution Modeling (Maxent) and Genetic Algorithm for Rule-set Prediction (GARP), were used to develop models in Iowa for three species of mosquito — two significant, extant West Nile virus (WNV) vectors (Culex pipiens L and Culex tarsalis Coquillett (Diptera: Culicidae)), and the nuisance mosquito, Aedes vexans Meigen (Diptera: Culicidae), a potential WNV bridge vector. Occurrence data for the three mosquito species from a state-wide arbovirus surveillance program were used in combination with climatic and landscape layers. Maxent successfully created more appropriate niche models with greater accuracy than GARP. The three Maxent species' models were combined and the average values were statistically compared to human WNV incidence at the census block group level. The results showed that the Maxent-modeled species' niches averaged together were a useful indicator of WNV human incidence in the state of Iowa. This simple method for creating probability distribution maps proved useful for understanding WNV dynamics and could be applied to the study of other vector-borne diseases

Evaluation of preservation methods for selected nutrients in ground water at the Idaho National Engineering Laboratory, Idaho

Water from 28 wells completed in the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL) was sampled as part of the US Geological Survey`s quality-assurance program to determine the effect of different preservation methods on nutrient concentrations. Samples were preserved with filtration and with mercuric chloride and chilling, chilling only, or sulfuric acid and chilling. The samples were analyzed for ammonia, nitrite, nitrite plus nitrate, and orthophosphate by the US Geological Survey National Water Quality Laboratory. The study was done in cooperation with the US Department of Energy. The comparison between samples preserved with mercuric chloride and chilling and samples preserved by chilling only showed that all sample pairs were in statistical agreement. Results for ammonia and nitrite plus nitrate samples preserved with sulfuric acid and chilling were within the 95 percent confidence level of the results for the samples preserved by the other two methods and can be considered equivalent to them. Results of this study indicate that discontinuing the use of mercuric chloride as a preservation method for nutrients in water samples will not affect the comparability of data collected at the INEL before and after October 1, 1994

Plant essential oils synergize various pyrethroid insecticides and antagonize malathion in Aedes aegypti

Pyrethroid resistance is a significant threat to agricultural, urban and public health pest control activities. Because economic incentives for the production of novel active ingredients for the control of public health pests are lacking, this field is particularly affected by the potential failure of pyrethroid‐based insecticides brought about by increasing pyrethroid resistance. As a result, innovative approaches are desperately needed to overcome insecticide resistance, particularly in mosquitoes that transmit deadly and debilitating pathogens. Numerous studies have demonstrated the potential of plant essential oils to enhance the efficacy of pyrethroids. The toxicity of pyrethroids combined with plant oils is significantly greater than the baseline toxicity of either oils or pyrethroids applied alone, which suggests there are synergistic interactions between components of these mixtures. The present study examined the potential of eight plant essential oils applied in one of two concentrations (1% and 5%) to enhance the toxicity of various pyrethroids (permethrin, natural pyrethrins, deltamethrin and β‐cyfluthrin). The various plant essential oils enhanced the pyrethroids to differing degrees. The levels of enhancement provided by combinations of plant essential oils and pyrethroids in comparison with pyrethroids alone were calculated and synergistic outcomes characterized. Numerous plant essential oils significantly synergized a variety of pyrethroids; type I pyrethroids were synergized to a greater degree than type II pyrethroids. Eight plant essential oils significantly enhanced 24‐h mortality rates provided by permethrin and six plant essential oils enhanced 24‐h mortality rates obtained with natural pyrethrins. By contrast, only three plant essential plants significantly enhanced the toxicity of deltamethrin and β‐cyfluthrin. Of the plant essential oils that enhanced the toxicity of these pyrethroids, some produced varying levels of synergism and antagonism. Geranium, patchouli and Texas cedarwood oils produced the highest levels of synergism, displaying co‐toxicity factors of \u3e 100 in some combinations. To assess the levels of enhancement and synergism of other classes of insecticide, malathion was also applied in combination with the plant oils. Significant antagonism was provided by a majority of the plant essential oils applied in combination with this insecticide, which suggests that plant essential oils may act to inhibit the oxidative activation processes within exposed adult mosquitoes

Biodistribution of degradable polyanhydride particles in Aedes aegypti tissues

Insecticide resistance poses a significant threat to the control of arthropods that transmit disease agents. Nanoparticle carriers offer exciting opportunities to expand the armamentarium of insecticides available for public health and other pests. Most chemical insecticides are delivered by contact or feeding, and from there must penetrate various biological membranes to reach target organs and kill the pest organism. Nanoparticles have been shown to improve bioactive compound navigation of such barriers in vertebrates, but have not been well-explored in arthropods. In this study, we explored the potential of polyanhydride micro- and nanoparticles (250 nm– 3 μm), labeled with rhodamine B to associate with and/or transit across insect biological barriers, including the cuticle, epithelium, midgut and ovaries, in female Ae. aeygpti mosquitoes. Mosquitoes were exposed using conditions to mimic surface contact with a residual spray or paint, topical exposure to mimic contact with aerosolized insecticide, or per os in a sugar meal. In surface contact experiments, microparticles were sometimes observed in association with the exterior of the insect cuticle. Nanoparticles were more uniformly distributed across exterior tissues and present at higher concentrations. Furthermore, by surface contact, topical exposure, or per os, particles were detected in internal organs. In every experiment, amphiphilic polyanhydride nanoparticles associated with internal tissues to a higher degree than hydrophobic nanoparticles. In vitro, nanoparticles associated with Aedes aegypti Aag2 cells within two hours of exposure, and particles were evident in the cytoplasm. Further studies demonstrated that particle uptake is dependent on caveolae-mediated endocytosis. The propensity of these nanoparticles to cross biological barriers including the cuticle, to localize in target tissue sites of interest, and to reach the cytoplasm of cells, provides great promise for targeted delivery of insecticidal candidates that cannot otherwise reach these cellular and subcellular locations

Radionuclides, stable isotopes, inorganic constituents, and organic compounds in water from selected wells and springs from the southern boundary of the Idaho National Engineering Laboratory to the Hagerman Area, Idaho, 1994

The US Geological Survey and the Idaho Department of Water Resources, in response to a request from the US Department of Energy, samples 18 sites as part of a long-term project to monitor water quality of the Snake River Plain aquifer from the southern boundary of the Idaho National Engineering Laboratory to the Hagerman area. Water samples were collected and analyzed for selected radionuclides, stable isotopes, inorganic constituents, and organic compounds. The samples were collected from seven irrigation wells, seven domestic wells, two springs, one stock well, and one observation well. Two quality assurance samples also were collected and analyzed. None of the radionuclide, inorganic constituent, or organic compound concentrations exceeded the established maximum contaminant levels for drinking water. Many of the radionuclide and inorganic constituent concentrations exceeded their respective reporting levels. All samples analyzed for dissolved organic carbon had concentrations that exceeded their minimum reporting levels

Evaluation of radionuclide, inorganic constituent, and organic compound data from selected wells and springs from the southern boundary of the Idaho National Engineering Laboratory to the Hagerman area, Idaho, 1989--1992

The U.S. Geological Survey and the Idaho Department of Water Resources, in cooperation with the U.S. Department of Energy, evaluated the water quality data collected from 55 wells and springs during 1989 and 1990 through 1992 from the southern boundary of the Idaho National Engineering Laboratory to the Hagerman area, Idaho. Water samples collected in 1989-92 were analyzed for selected radionuclides, inorganic constituents, and organic compounds. A statistical comparison between data collected in 1989 and data collected in 1990-92 along with a comparison of replicate pairs was used to evaluate changes in water quality between samples and to assess sampling and analysis precision for individual constituents. The comparisons of radionuclide data showed no pattern of water quality change between samples as concentrations randomly increased or decreased. Tritium concentrations did show a consistent pattern with location in the aquifer. The largest tritium concentrations occurred in water from wells in the Big Wood and Little Wood River drainages and in the southern part of the study area where heavy irrigation occurs. The variability of radionuclide concentrations may be attributed to the change in the contract laboratory used for radiochemical analyses between 1989 and 1990. The replicate data for radionuclides showed better overall reproducibility for data collected in 1990-92 than for 1989, as 70 of 76 replicate pairs were statistically equivalent for 1990-92 data whereas only 55 of 73 replicate pairs were equivalent for 1989 data. The comparisons of most of the inorganic constituent data showed no statistical change between samples. Exceptions include nitrite plus nitrate as nitrogen and orthophosphate as phosphorus data. Fifteen sample pairs for nitride plus nitrate and 18 sample pairs for orthophosphate were not statistically equivalent and concentrations randomly increased or decreased

Determination of the angle of attack on a research wind turbine rotor blade using surface pressure measurements

In this paper, a method to determine the angle of attack on a wind turbine rotor blade using a chordwise pressure distribution measurement was applied. The approach used a reduced number of pressure tap data located close to the blade leading edge. The results were compared with the measurements from three external probes mounted on the blade at different radial positions and with analytical calculations. Both experimental approaches used in this study are based on the 2-D flow assumption; the pressure tap method is an application of the thin airfoil theory, while the probe method applies geometrical and induction corrections to the measurement data. The experiments were conducted in the wind tunnel at the Hermann Föttinger Institut of the Technische Universität Berlin. The research turbine is a three-bladed upwind horizontal axis wind turbine model with a rotor diameter of 3 m. The measurements were carried out at rated conditions with a tip speed ratio of 4.35 and different yaw and pitch angles were tested in order to compare the approaches over a wide range of conditions. Results show that the pressure tap method is suitable and provides a similar angle of attack to the external probe measurements as well as the analytical calculations. This is a significant step for the experimental determination of the local angle of attack, as it eliminates the need for external probes, which affect the flow over the blade and require additional calibration

REVISIÓN TAXONÓMICA DEL GÉNERO Timulla ASHMEAD, 1899 DE PANAMÁ (HYMENOPTERA: MUTILLIDAE)

The males of Timulla chrysea Mickel, 1938, Timulla continua Mickel, 1938, and Timulla segesta Mickel, 1938, and the female of Timulla tumidula (Cameron, 1894) are described and illustrated. Timulla chrysea and T. tumidula are reported for first time from Panama. The following synonyms are presented: Timulla orthona (Cameron, 1894), male, is a junior synonym of Timulla lilea (Cameron, 1894), female; Timulla talus (Cameron, 1894), male, is a junior synonym of Timulla subrobusta (Cameron, 1894), female. Observations on mating behavior for Timulla runata Mickel and Timulla cordillera Mickel, 1938 are described. Flight seasonality of Timulla labdace Mickel, 1938 is discussed. Keys and a checklist for the 16 species of Timulla from Panama are presented.Los machos de Timulla chrysea Mickel, 1938, Timulla continua Mickel, 1938 y Timulla segesta Mickel, 1938 y la hembra de Timulla tumidula (Cameron, 1894) son descritos e ilustrados. Se registran por primera vez para Panamá a Timulla chrysea y T. tumidula. Las siguientes sinonimias son presentadas: Timulla orthona (Cameron, 1894), macho, es junior sinónimo de Timulla lilea (Cameron, 1894), hembra; Timulla talus (Cameron, 1894), macho, es junior sinónimo de Timulla subrobusta (Cameron, 1894), hembra. Observaciones sobre el comportamiento de apareamiento para Timulla runata Mickel y T. cordillera son descritos. Estacionalidad de vuelo en Timulla labdace Mickel, 1938 es discutido. Se incluye una clave y listado para las 16 species of Timulla presentes en Panamá

Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 m, and the blade configurations consist of the clean and the tripped baseline cases, emulating the effects of forced leading-edge transition. The wind tunnel experiments include three operation points based on tip speed ratios of 3.0, 4.3, and 5.6, reaching Reynolds numbers of approximately 2.5×105. The measurements are taken by means of three different methods: Ultrasonic anemometry in the wake, surface pressure taps in the midspan blade region, and strain gauges at the blade root. The retrofit applications consist of two Gurney flap heights of 0.5% and 1.0% in relation to the chord length, which are implemented perpendicular to the pressure side at the trailing edge. As a result, the Gurney flap configurations lead to performance improvements in terms of the axial wake velocities, the angles of attack and the lift coefficients. The enhancement of the root bending moments implies an increase in both the rotor torque and the thrust. Furthermore, the aerodynamic impact appears to be more pronounced in the tripped case compared to the clean case. Gurney flaps are considered a passive flow-control device worth investigating for the use on horizontal-axis wind turbines