The Variable Polarity Plasma Arc Welding Process: Its Application to the Space Shuttle External Tank

This report describes progress in the implementation of the Variable Polarity Plasma Arc Welding (VPPAW) process at the External Tank (ET) assembly facility. Design allowable data has been developed for thicknesses up to 1.00 in. More than 24,000 in. of welding on liquid oxygen and liquid hydrogen cylinders has been made without an internal defect

The variable polarity plasma arc welding process: Its application to the Space Shuttle external tank

The technical history of the variable polarity plasma arc (VPPA) welding process being introduced as a partial replacement for the gas shielded tungsten arc process in assembly welding of the space shuttle external tank is described. Interim results of the weld strength qualification studies, and plans for further work on the implementation of the VPPA process are included

Temperature effects on dislocation core energies in silicon and germanium

Temperature effects on the energetics of the 90-degree partial dislocation in silicon and germanium are investigated, using non-equilibrium methods to estimate free energies, coupled with Monte Carlo simulations. Atomic interactions are described by Tersoff and EDIP interatomic potentials. Our results indicate that the vibrational entropy has the effect of increasing the difference in free energy between the two possible reconstructions of the 90-degree partial, namely, the single-period and the double-period geometries. This effect further increases the energetic stability of the double-period reconstruction at high temperatures. The results also indicate that anharmonic effects may play an important role in determining the structural properties of these defects in the high-temperature regime.Comment: 8 pages in two-column physical-review format with six figure

Genotype x environment interaction, adaptability and stability of 'Piel de Sapo' melon hybrids through mixed models.

Made available in DSpace on 2020-01-17T18:08:18Z (GMT). No. of bitstreams: 1 ART19121.pdf: 395810 bytes, checksum: 4aba9c9c559e21362d8a1c2d46a17e2a (MD5) Previous issue date: 2019bitstream/item/209064/1/ART19121.pd

Implantação e evolução dos trabalhos de pesquisa participativa em melhoramento de mandioca no Nordeste Brasileiro.

Este trabalho faz um breve histórico sobre a implantação e os avanços da pesquisa participativa em melhoramento de mandioca (PPMM) no Nordeste do Brasil, desenvolvida pela Embrapa Mandioca e Fruticultura. A metodologia de pesquisa participativa em melhoramento de mandioca foi desenvolvida inicialmente no Centro Internacional de Agricultura Tropical (CIAT), na Colômbia e introduzida e adaptada as condições das regiões semi-árida do Nordeste brasileiro a partir de 1993. Os primeiros resultados demostraram que a metodologia de PPMM como um complemento ao método convencional de melhoramento genético da cultura.bitstream/item/81562/1/Implantacao-evolucao-Wania-Fukuda-Docuemntos-92-2000.pdfMemória

Ochratoxin A and filamentous fungi in red wine grapes from Santa Catarina, Brazil

The quality of wines has been evaluated traditionally according to sensorial properties. Recently, safety issues have been raised, such as pesticide residues and mycotoxins, with the introduction of new agricultural practices and the development of analytical methods with higher sensitivity. Ochratoxin A (OTA) is such a mycotoxin, produced by some Aspergillus and Penicillium species and is one of the most recent safety issues for wine. The mycobiota of, and the occurrence of OTA in Southern Brazilian grapes are not known. The presence of these contaminants was assessed by collecting 30 samples of grapes, from 16 vineyards, from the two most important wine subregions in the State of Santa Catarina, Brazil. The mycobiota was evaluated by plating 10 grapes from each sample in Dichloran Rose Bengal Chloramphenicol Agar and Sabouraud Dextrose Agar, supplemented with chloramphenicol. Production of OTA by black Aspergillus strains was estimated after growing in Czapeck Yeast Agar. OTA was analysed in 9 grape samples by chromatography with immunoaffinity clean-up, as stipulated by the European regulation. Three hundred and eighty seven strains were isolated. The dominant genera were Cladosporium (found in 86.7% of plated berries), Alternaria (80.0%), Botrytis (70.0%), Aspergillus (66.7%), and Penicillium (63.3%). Sixteen A. niger aggregate strains (26 % of total Aspergillus strains) were isolated, and OTA was not detected from any of these strains. No A. carbonarius was isolated. OTA was found in 6 grape samples, with a range of values from 0.16 μg/Kg to 0.77 μg/Kg. In conclusion, no OTA producing black Aspergillus strains were found in grapes, although some grape samples contain the mycotoxin. The fungal source of OTA requires further investigation