Search Results - (Author, Cooperation:I. C. Chen)

2016-03-26

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; *Climate ; *Global Warming ; *Seasons ; *Temperature ; Vertebrates/*physiology

2011-08-20

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

*Altitude ; Animals ; *Behavior, Animal ; *Climate Change ; *Ecosystem ; *Environment ; Geography ; Population Dynamics ; Species Specificity ; Time Factors

1089-7550

AIP Digital Archive

Physics

The susceptibility to hole trapping of the gate oxide of a metal-oxide-silicon (MOS) device is not necessarily proportional to the efficiency of interface trap generation at the Si-SiO2 interface, which is widely believed due to the recombination of electrons and trapped holes in the oxide close to the interface. In this study, an oxide given a high-temperature (1000 °C) anneal, which increases the hole trapping efficiency of the oxide, is shown to have much less generated interface traps compared to a normal oxide (without high-temperature annealing) upon exposing to ionizing radiation with subsequent electron injection, or high-field injection alone. Under high-field tunneling injection, the electron fluence required to create a certain density of interface trap is an order of magnitude higher for the annealed oxide compared to the normal oxide. These results could provide a possible direction for improving the reliability of the gate oxide of a MOS field-effect transistor.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

It is shown that after holes are injected and trapped in silicon dioxide (SiO2), subsequent electron injection will generate neutral electron traps. The density of electron traps generated is about 30% of the density of trapped holes. It is proposed that electron traps are created by the energy released through the recombination of electrons and holes, and that this is the mechanism of electron-trap generation during high-field oxide stressing. Similar oxide field and thickness dependencies of the rate of electron-trap generation and hole generation further support this model. This model can reconcile the main evidence for the electron-trapping oxide breakdown model with the hole-trapping breakdown model. It is consistent with the higher trap generation rate in irradiated SiO2. An analytical trapping model is derived and the electron capture cross sections of trapped holes and the generated neutral traps are found to be 10−14 cm2 and 5×10−16 cm2, respectively.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

: The quality of phytoestrogenic licorice was studied by using both chemical and biological fingerprints. A recombinant yeast strain that consists of an estrogen responsive element linked with a reporter gene (ADE2) and a transformed human estrogen receptor–containing plasmid was used for screening and evaluation of estrogenic activity in licorice. Several estrogen-like components in licorice were screened, and licoisoflavone B and formononetin were identified. Licorice extracted with 70% ethanol showed 5 different patterns of chemical fingerprints (LR-A, LR-E, LR-F, LR-H, LR-K), as identified by chromatographic analysis. Among these, LR-E exhibited the strongest estrogenic activity, whereas LR-A, LR-F, and LR-H were in the middle, and LR-K had the weakest activity.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Sturgeon species have attracted interest for aquaculture due to high value of the flesh, caviar and wild stock depletion. Lipid was extracted from sturgeon muscle using the Bligh and Dyer procedure. Fatty acids from total lipid were methylated using boron-trifluoride in methanol. Fatty acid methyl esters were analyzed by gas chromatography as weight %. The fatty acid profiles of lipids were different between cultured and wild sturgeon. Wild sturgeon had higher levels of 16:0, 16:1ω7, 18:1ω9, 22: 4ω6 and 22:5ω6. Cultured fish had higher levels of 18:2ω6, C20 and C22 monoenes, 20:5ω3 and 22:6ω3. Stepwise discriminant analysis (SDA) was used to develop a mathematical model to distinguish the two populations; the levels of 16:2ω6, 22:5ω6 and phytanic acid accurately identified the two fish populations.

Electronic Resource

0925-4005

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electrical Engineering, Measurement and Control Technology

Electronic Resource

0021-9673

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0022-2852

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Physics

Electronic Resource

0009-2614

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Physics

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) analyses of caviar were used to identify species of American, European and Asian sturgeon. Caviar samples of American and Gulf of Mexico sturgeon showed distinctive protein banding patterns on SDS-PAGE. IEF gels containing 20% pH 3-10 and 80% pH 4-6.5 ampholyte enabled differentiation of sturgeon species. IEF was more reliable than SDS-PAGE for identification of sturgeon species.

Electronic Resource

1573-4889

INTERNAL NITRIDING ; Co-Fe-Al ALLOYS ; KINETICS ; NITROGEN PERMEABILITIES ; PRECIPITATE MORPHOLOGY

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract Co-10Fe, Co-20Fe, and Co-40Fe alloys containing3 at.% Al were internally nitrided inNH3/H2 mixtures over the range700-1000°C. The kinetics of thickening of theinternal-reaction zone followed the parabolic rate law, suggesting thatsolid-state diffusion was rate controlling. Nitrogenpermeabilities were obtained for each alloy. AlN was theonly nitride to form for all materials and at alltemperatures. At high temperature, the nitride precipitatesformed hexagonal plates near the surface, theprecipitates becoming more blocky near the reactionfront. Precipitate size increased with increasing depthin the alloy and increasing temperature, becauseof competition between nucleation and growth processes.Increasing iron content increased the reacion kineticsdue to increased nitrogen solubility with increasing iron content.

Electronic Resource

1573-4889

Internal nitriding ; 310 stainless steel ; austenitic ; kinetics ; microhardness

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The internal-nitriding behavior in ammonia-hydrogen atmospheres of type-310 stainless steel and 310 to which either 2 wt.% Ti or 3 wt.% Al were added was studied over the range of 550–950°C. An Fe-24Cr binary alloy was included to assess the role of a BCC crystal structure vs the FCC crystal structure of 310 stainless steel. The BCC alloy exhibited the most rapid kinetics as expected. X-ray diffraction showed only the presence of CrN in all the alloys up to 735°C. At 850°C and above, both CrN and Cr2N were detected. The nonformation of TiN and AlN at lower temperatures is attributed to nucleation problems. Precipitates were extremely fine (unresolvable even at 20,000×) at 563°C and became much coarser with increasing temperature. The precipitate density, size, and shape varied across the internal-nitriding zone at the higher temperatures. External scaling was noted at 850°C and above, however, it was not a continuous film. The activation energy of internal nitriding from 563–735°C ranged from 3.8 kcal/mol for 310+2Ti to 18.2 kcal/mol for 310+3Al; from 850–950°C, the activation energy ranged from 44 (310+2Ti) to 56.6 kcal/mol (310+3Al). Microhardness profiles show that an intermediate zone exists between the nitride case and the base metal. The origin of this zone is discussed.

Electronic Resource

1573-4889

nitriding ; nitrogen diffusivity ; nitrogen solubility ; cobalt alloys

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract Internal nitridation of Co containing 3 a/o of either Cr, Al, or Ti was studied over the range of 700–1100° C in NH3/H2 (6∶94 ratio). The kinetics of thickening of the reaction zone followed the parabolic rate law, suggesting that solidstate diffusion was rate controlling. Activation energies obtained were 51.2 Kcal/molfor Co-3Cr, 46.6 Kcal/mol for Co-3Ti, and 27.9 Kcal/mol for Co-3Al. XRD showed only CrN, AlN, and TiN. Deep etching revealed that AlN formed hexagonal plates near the surface when formed at high temperature, the precipitates becoming more massive (blocky morphology) near the reaction front. TiN formed elongated dendritic precipitates, whereas CrN tended to form spheroids. The precipitate size varied with temperature, decreasing with decreasing temperature. In some cases, nitriding formed a case but no visible precipitates even at very high magnifications in the SEM. The solubility of nitrogen in cobalt was determined by long-time equilibration and subsequent chemical analyses. The diffusivity of nitrogen in cobalt was determined from measured permeabilities and the experimentally determined solubilities. Mechanisms are discussed, and the behavior of internal nitridation is compared with internal carburization and oxidation in cobalt alloys.

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract YBCO thin film was prepared by the spin-coating method with metal-organic precursors. The precursors were synthesized by reacting metal acetates with 2-ethylhexanic acid or by reacting metal halides with ammonium 2-ethylhexanate directly. After proper heat treatments, YBCO film with T c, onset = 80 K and T c,zero = 77 K was obtained. SEM studies of a sample prepared at 990 °C showed the presence of CuO and Ba2YCuO5 (211 phase). This suggested the transient presence of a liquid phase which had been observed in preparing YBCO bulk material by the melt-texture method before the formation of YBCO phase. Furthermore, many voids were observed in the as-obtained film. These might be the origin of the relatively low T c,zero, temperature.

Electronic Resource