Distribution of oxygen in silicon and its effects on electronic characteristics on a microscale

The microdistribution of oxygen in silicon was obtained by scanning IR absorption in as grown Czochralski crystals. The crystals were subsequently submitted to various heat treatments. The profiles of the generated thermal donors were determined by spreading resistance measurements. Contrary to the prevailing views, it was found that the concentration of the activated thermal donors is not strictly a function of the oxygen concentration, but depends strongly on an additional factor, which was shown to be associated with vacancy concentration. These conclusions could only be reached on the basis of microscale characterization. In fact, commonly employed macroscale analysis has led to erroneous conclusions

Utilização de crotalária no controle de nematóides da raiz do feijoeiro.

Este trabalho teve como objetivo avaliar o efeito da palhada de C. spectabilis no controle de nematóides da raiz do feijoeiro.bitstream/CNPAF/22189/1/comt_74.pd

The use of exogenous microbial species to enhance the performance of a hybrid fixed-film bioreactor treating coal gasification wastewater to meet discharge requirements

The objective of this study was to determine whether inoculating a hybrid fixed-film bioreactor with exogenous bacterial and diatoma species would increase the removal of chemical oxygen demand, nitrogenous compounds and suspended solids from a real-time coal gasification wastewater to meet environmental discharge requirements specified for petrochemical refineries. The COD removal increased by 25% (45% to 70%) at a relatively high inoculum dosage (370 g∙m−3) and unit treatment cost (12.21 €∙m−3). The molar ratio of monovalent cations to divalent cations (M/D >2) affected nitrification, settling of solids and dewatering of the sludge. The use of a low-charge cationic flocculant decreased the suspended solids in the effluent by 70% (180 mg∙L−1 to 54 mg∙L−1) and increased the sludge dewatering rate by 88% (61 s∙L∙g−1 to 154 s∙L∙g−1) at a unit treatment cost of 2.5 €∙t−1 dry solids. Organic compounds not removed by the indigenous and exogenous microbial species included benzoic acids (aromatic carboxylic acids), 2-butenoic acid (short-chain unsaturated carboxylic acid), I(2H)-isoquinolinone (heterocyclic amine), hydantoins (highly polar heterocyclic compounds), long-chain hydrocarbon length (carbon length > C15) and squalene. These organic compounds can thus be classified as poorly degradable or nonbiodegradable which contributed to the 30% COD not removed by the H-FFBR. The use of exogenous microbial species improved the quality of CGWW; however, not sufficiently to meet discharge requirements. The cost of such treatment to meet discharge requirements would be unsustainable. Alternative technologies need to be investigated for reusing or recycling the CGWW rather than discharging.Keywords: ammonia, catalytic reactor technology, COD, fixed-film bioreactor, hydantoins, thiocyanate

Low-Cost Heaving Single-Buoy Wave-Energy Point Absorber Optimization for Sardinia West Coast

This work presents the Water Energy Point Absorber (WEPA), which is a heaving single-buoy point absorber optimized for a specific site off the west coast of Sardinia Island. The aim of the study is to present the optimization process undertaken to identify the best configuration in terms of performance and cost. The optimization is carried out thanks to a simulation tool developed in Matlab-Simulink environment and verified through to the commercial software Orcaflex. Simulations are performed in the time domain with the installation site’s waves as input. The hydrodynamics parameters are computed thanks to the commercial software Ansys Aqwa and given to the model as input. The yearly energy production is computed as output for each configuration. Several parametric analyses are performed to identify the optimal Power Take Off (PTO) and buoy size. Among the main findings, it shall be mentioned that the PTO-rated torque has a strong influence on the energy production, higher PTO-rated torque proved to have better performance. The optimal hull size is strictly related to the incoming waves, and for the given site the smaller hulls are performing better than larger ones. The hull height, hull mass and hull draft have little impact on productivity. Finally, a comprehensive techno–economic analysis is performed, showing that the best configuration can be identified only after a detailed feasibility study and rigorous cost analysis

Avaliação de perdas causadas pela mancha angular do feijoeiro comum.

O presente ensaio, realizado no CNPAF teve por finalidade a determinação das perdas ocasionadas por esta enfermidade na cultura do feijoeiro

Comportamento de cultivares de feijão (Phaseolus vulgaris L.) a Isariopsis griseola.

Para se estudar a reaçãO de cultivares de feijão à mancha angular e obter possíveis fontes de resistência, instalou-se um ensaio constando de variedades do Viveiro Nacional de Mancha Angular do CNPAF-EMBRAPA/IPA, no Campo Experimental de Caruaru- PE, no perlodo de 1978-80

Comparação da eficiência de métodos de seleção em gerações segregantes de feijoeiro-comum considerando a resistência à antracnose e o rendimento.

Vários métodos de melhoramento podem ser utilizados para o desenvolvimento de cultivares de feijoeiro-comum (Phaseolus vulgaris L.). Com este trabalho, teve-se por objetivo comparar quatro métodos de melhoramento, seleção massal modificada, famílias derivadas de populações nas gerações F3 e F4, e o genealógico, quanto à eficiência na obtenção de linhagens resistentes à antracnose (Colletotrichum lindemuthianum (Sacc. e Magn.) Scrib.) e com alta produtividade. O maior número de linhagens resistentes à antracnose foi obtido pelo método de seleção massal modificada. As linhagens obtidas pelo método de famílias derivadas de população na geração F4 apresentaram a maior variabilidade genética. Considerando conjuntamente a porcentagem de linhagens resistentes à C. lindemuthianum, a produtividade média das linhagens, a variância genética entre as linhagens geradas por cada método, o número e o percentual de linhagens com produtividade superior à testemunha, a eficiência do método variou com o critério utilizado para compará-los. Os genitores e a interação linhagem x local influenciaram a interpretação dos resultados obtidos com os diferentes critérios de avaliação utilizados para a comparação dos métodos de seleção

Chemotaxis When Bacteria Remember: Drift versus Diffusion

{\sl Escherichia coli} ({\sl E. coli}) bacteria govern their trajectories by switching between running and tumbling modes as a function of the nutrient concentration they experienced in the past. At short time one observes a drift of the bacterial population, while at long time one observes accumulation in high-nutrient regions. Recent work has viewed chemotaxis as a compromise between drift toward favorable regions and accumulation in favorable regions. A number of earlier studies assume that a bacterium resets its memory at tumbles -- a fact not borne out by experiment -- and make use of approximate coarse-grained descriptions. Here, we revisit the problem of chemotaxis without resorting to any memory resets. We find that when bacteria respond to the environment in a non-adaptive manner, chemotaxis is generally dominated by diffusion, whereas when bacteria respond in an adaptive manner, chemotaxis is dominated by a bias in the motion. In the adaptive case, favorable drift occurs together with favorable accumulation. We derive our results from detailed simulations and a variety of analytical arguments. In particular, we introduce a new coarse-grained description of chemotaxis as biased diffusion, and we discuss the way it departs from older coarse-grained descriptions.Comment: Revised version, journal reference adde