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1

Microstructure Evolution of Tungsten-Based ODS Alloys Reinforced with the γ(Ni,~Fe) Phase by a Secondary Ball Milling Method

100%

Chen C., Zeng Y., Lee J.

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vol. 126

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issue 4

907-911

EN

In the current study, W-5Ni-2Fe-Y_2O_3 model alloys were produced using a high-energy planetary ball mill. The presence of the γ(Ni, Fe) phase is favored with respect to material properties in this alloy. Therefore, a secondary ball milling method was introduced to obtain a fine and uniformly distributed γ(Ni, Fe) phase. Phase development of mechanical alloyed powders was investigated by X-ray diffraction. The results show that the formation of the γ(Ni, Fe) phase was found after 18 h of a pre-milling procedure. A further secondary milling method produced a uniform microstructure with grain refinement. TEM results also show changes in the lattice parameters of the tungsten and γ(Ni, Fe) phase associated with the solid solubility limits in the alloy produced by secondary ball milling.

2

Calculation of interval damping ratio under uncertain load in power system

100%

Xing J., Chen C., Wu P.

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2012

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issue 1

3

A new scheme for power factor correction and active filtering for six-pulse converters loads

76%

Han Y., Khan M., Xu L., Yao G., Zhou L., Chen C.

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2009

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vol. 57

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issue 2

4

Signal transduction in human pancreatic cancer: roles of transforming growth factor beta, somatostatin receptors, and other signal intermediates

76%

Li M., Becnel L. S., Li W., Fisher W. E., Chen C., Yao Q.

Archivum Immunologiae et Therapiae Experimentalis

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2005

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vol. 53

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issue 5

381-387

EN

Pancreatic cancer is a devastating disease because of the lack of early detection markers and effective treatments. It is the fourth leading cause of cancer-related death in western countries, including the United States. The mechanisms of pancreatic cancer progression remain unknown. Transforming growth factor beta (TGF-beta), a multifunctional cytokine, regulates cell growth and differentiation in healthy tissues, yet fails to do so in pancreatic cancer. Alterations of the TGF-beta and TGF-beta receptor/Smad signal transduction pathway have been implicated in pancreatic cancer. Furthermore, both the TGF-beta receptor and Smad proteins interact with a variety of cellular signal pathways, such as the somatostatin receptors (SSTRs), ERK1/2, and Wnt signal transduction cascades. This suggests that pancreatic cancer is a multi-gene-controlled malignancy and that effective treatments for pancreatic cancer should be aimed at multiple targets. In this review, we summarized the major signal intermediates involved in pancreatic cancer signal transduction pathways and specifically discussed how alterations in the regulatory functions of TGF-beta and Smad proteins allow for pancreatic carcinogenesis.

5

Luminescence of Highly Excited Nonpolar a-Plane GaN and AlGaN/GaN Multiple Quantum Wells

64%

Juršėnas S., Kuokštis E., Miasojedovas S., Kurilčik G., Žukauskas A., Chen C., Yang J., Adivarahan V., Asif Khan M.

Acta Physica Polonica A

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2004

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vol. 105

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issue 6

567-573

EN

Carrier recombination dynamics in polar and nonpolar GaN epilayers and GaN/AlGaN multiple quantum wells grown over sapphire substrates with various crystallographic orientation were studied under high photoexcitation by 20 ps laser pulses. The transient of luminescence featured a significant enhancement in nonradiative recombination of free carriers for nonpolar a-plane GaN epilayers compared to conventional c-plane samples. The epitaxial lateral overgrowth technique was demonstrated to significantly improve the quality of nonpolar a-plane films. This was proved by more than 40-fold increase in luminescence decay time (430 ps compared to ≤10 ps in the ordinary a-plane epilayer). Under high-excitation regime, a complete screening of built-in electric field by free carriers in multiple quantum wells grown on c-plane and r-plane sapphire substrates was achieved. Under such high excitation, luminescence efficiency and carrier lifetime of multiple quantum wells was shown to be determined by the substrate quality.

6

Luminescence of Highly Photoexcited GaN Epilayers and Heterostructures Grown on Different Sapphire Crystal Planes

64%

Juršėnas S., Miasojedovas S., Kurilčik G., Liuolia V., Žukauskas A., Chen C., Yang J., Kuokštis E., Adivarahan V., Asif Khan M.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

235-239

EN

GaN epilayers and AlGaN/GaN multiple quantum wells grown by metalorganic chemical vapor deposition on different crystal planes (c, a, and r) of the sapphire substrate were studied by excitation intensity dependent and time-resolved photoluminescence. In polar multiple quantum wells grown on a- and c-planes, a blueshift of the luminescence band with increasing the excitation energy was observed, indicating that screening of built-in field by free carriers takes place, whereas in nonpolar r-plane grown multiple quantum wells, the luminescence band maintained an almost constant peak position. Full screening of built-in field was achieved at the excitation densities higher than 0.3 mJ/cm^2. Under conditions of screened built-in electric field the structures were characterized by carrier lifetime. It was shown that nonpolar multiple quantum wells suffer from high density of nonradiative traps that can be due to substrate related threading dislocations.

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