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81.
S.S.M. Tavares J.M. Pardal A.M. Gomes 《Journal of magnetism and magnetic materials》2010,322(17):L29-451
Duplex stainless steels are high strength and corrosion resistant steels extensively used in the chemical and petrochemical industry. The best mechanical properties and corrosion resistance are obtained with a microstructure composed by equal parts of ferrite and austenite and free from tertiary phases. Sigma phase is one of these deleterious tertiary phases. In the present work different amounts of sigma phase were precipitated by heat treatments in a UNS S31803 stainless steel. Some specimens were cold rolled before sigma phase precipitation in order to evaluate the effect of deformation on the magnetic measurements. The amount of sigma phase was precisely determined by microscopy and image analysis for each heat treatment condition. The effects of sigma phase on the steel properties were investigated, confirming the detrimental effects of very small percentages on corrosion resistance and toughness. Two magnetic methods were used to detect sigma phase: magnetization saturation measurements in a Vibrating Sample Magnetometer and ferritoscope testing. Both methods were found to be sensitive to small percentages of sigma phase in the microstructure. 相似文献
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For the positive solutions of the Gross–Pitaevskii system we prove that L∞‐boundedness implies C0,α‐boundedness for every α ? (0,1), uniformly as β → +∞. Moreover, we prove that the limiting profile as β → +∞ is Lipschitz‐continuous. The proof relies upon the blowup technique and the monotonicity formulae by Almgren and Alt, Caffarelli, and Friedman. This system arises in the Hartree‐Fock approximation theory for binary mixtures of Bose–Einstein condensates in different hyperfine states. Extensions to systems with k > 2 densities are given. © 2009 Wiley Periodicals, Inc. 相似文献
84.
Vânia P. Campos Adriana S. Oliveira Lícia P.S. Cruz Jomar Borges Tania M. Tavares 《Microchemical Journal》2010,96(2):283-289
Reduced sulfur compounds, RSCs (H2S, COS, CH3SH, CH3SCH3, CS2 and CH3S2CH3) play a role in global cycle and acid rain formation. At trace levels RSCs in air are difficult to collect, store and analyze because of their highly adsorptive and reactive properties. This work optimizes parameters of sampling and instrumental determination of RSCs for urban measurements. The method used is based on cryogenic sampling and gas chromatography provided with a cryofocusing trap and flame photometric detection.Greater sampling efficiency was obtained with liquid argon as freezing fluid and air flow rate of 150 mL min? 1 for two hours. Best results have been obtained with preconcentration for 3 min and injection volume of 3 ml. For H2S, CH3SH and CH3S2CH3 the method showed a precision of 89%, limit of detection of 0.10 µg m? 3 and limit of quantification 0.3 µg m? 3. For CH3SCH3 and CS2 the corresponding values were 89%, 0.15 µg m? 3 and 0.5 µg m? 3 and for COS were 75%, 0.18 µg m? 3 and 0.8 µg m? 3 respectively. Sampling efficiency varied between 70–80% for all the RSCs. Accuracy of H2S from field measurements obtained with parallel measurements using a continuous monitor varied between 88 and 98%. The optimized methodology proved to be suitable for field measurements in urban tropical atmospheres with different characteristics. 相似文献
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Low power laser radiation at 685 nm stimulates stem-cell proliferation rate in Dugesia tigrina during regeneration 总被引:1,自引:0,他引:1
de Souza SC Munin E Alves LP Salgado MA Pacheco MT 《Journal of photochemistry and photobiology. B, Biology》2005,80(3):203-207
Today’s scientific interest in tissue engineering for organ transplantations and regeneration from stem cells, allied with recent observations on biostimulation of tissues and cells by laser radiation, stands as a strong motivation for the present work, in which we examine the effects of the low power laser radiation onto planarians under regenerative process. To investigate those effects, a number of 60 amputated worms were divided in three study groups: a control group and two other groups submitted to daily 1 and 3 min long laser treatment sections at 910 W/m2 power density. A 685 nm diode laser with 35 mW optical power was used. Samples were sent to histological analysis at the 4th, the 7th and the 15th days after amputation. A remarkable increase in stem cells counts for the fourth day of regeneration was observed when the regenerating worms was stimulated by the laser radiation. Our findings encourage further research works on the influence of optical radiation onto stem cells and tissue regeneration. 相似文献
90.
A. Diast Tavares 《Physics letters. A》1983,93(3):145-148
The self electrization during solidification of thin monocrystalline layers of naphthalene is studied as a function of the thickness x. Samples of naphthalene of different electrical conductivities are investigated. It is found that k, the electrical charge per mass of crystal, is an exponential function of x, each sample exhibiting two exponentials. The values of k are higher for the more conducting samples. 相似文献