Search Results - (Author, Cooperation:C. C. Wang)

2018-07-31

Institute of Physics (IOP)

1755-1307

1755-1315

Geography

Geosciences

Physics

2018-08-15

American Chemical Society (ACS)

1523-7060

1523-7052

Chemistry and Pharmacology

2018-04-13

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Microbiology

2012-04-28

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2013-05-04

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2012-02-11

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Humans ; *Language ; *Phonetics

2015-04-30

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Age Factors ; Awards and Prizes ; China ; Emigration and Immigration/statistics & numerical data ; Internationality ; Motivation ; *Personnel Selection ; Research Personnel/*economics/psychology/standards

2018-01-28

BMJ Publishing

2044-6055

Medicine

Oncology, Open access

2018-10-18

Royal Society

2054-5703

Natural Sciences in General

materials science

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

The picosecond electrical pulse-propagation characteristics of microchannel-plate detectors, used in diagnosing laser-driven inertial-confinement-fusion experiments, were measured with an electro-optic sampling system. We determined propagation velocity and signal distortion of the microchannel-plate microstrip, as well as its characteristic impedance and the substrate relative dielectric permittivity. These parameters are critical for proper calibration of the detectors and serve as a guide for their improved designs.

Electronic Resource

1550-7408

Blackwell Publishing Journal Backfiles 1879-2005

Biology

SYNOPSIS. Amylopectin granules were purified from Eimeria tenella oocysts following digestion with sodium dodecyl sulfate and pronase. The oval granules had a uniform size of 0.5 × 0.7 μm, and consisted of only glucose polymers. α-Amylase treatment yielded 235 nmoles of maltose from the granules from 106 unsporulated oocysts and 93 nmoles maltose from those from 106 sporulated oocysts.Amylopectin phosphorylase activity was detected in the cytoplasm of unsporulated oocysts of E. tenella. It had a specific activity of 13 U/mg protein in crude extracts, and a pH optimum of 6.0. The Km values determined were 9.1 mM for glucose-1-phosphate and 5.6 mM for glucose end groups in potato amylopectin. Enzyme activity declined at a linear rate during sporulation, sporulated oocysts containing less than 8% of the activity of unsporulated oocysts. No amylase-type activity was found in the parasite.

Electronic Resource

1550-7408

Blackwell Publishing Journal Backfiles 1879-2005

Biology

SYNOPSIS. The total content of DNA in Eimeria tenella, estimated at 5.8 × 10−12 gm/oocyst, varies little during sporulation. Its buoyant density is 1.682 gm/cm3, reflecting a G + C content of ∼41%. Thymidine is not incorporated into any TCA insoluble fraction of sporulating oocysts, but radioactivity from [3H]uridine and [3H]deoxyuridine are incorporated into RNA at a linear rate during the first 5 hr of sporulation. The labeled RNA, found mainly in the paranuclear bodies of newly formed sporozoites, contains ∼0.15 nmole [3H]uridine/106 oocysts at the completion of sporulation. One nmole of leucine is incorporated into the hot TCA insoluble fraction of 106 oocysts during the first 7 hr of sporulation after an initial lag. The incorporated amino acid is mainly in the cytoplasm of the sporozoites, and an analysis by SDS-gel electrophoresis reveals most of the radioactivity in a narrow band with a molecular weight of ∼50,000 daltons. Incorporation of uridine and leucine, however, can be totally suppressed by respiratory inhibition. Further analysis of the proteins in the oocysts reveals that the total protein content remains relatively unchanged at 2.64 × 10−16 gm/oocyst during sporulation, but there is a shift of 13–14% of total protein from the soluble cytoplasm to the 15,000 g pellets. By polyacrylamide gel electrophoresis, a major protein band. possibly a glycoprotein, is shown in the soluble cytoplasm of unsporulated oocysts. This band disappears during sporulation.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The ac electrical behavior of the polycrystalline yttria was evaluated in the temperature range of 800–1300 °C in air as a function of frequency (5 Hz≤f≤13 MHz). Resistance-temperature and resistance-time (aging) characteristics were examined using immittance measurements and electron microscopy to establish microstructure-property relationships. The ac electrical data indicated two distinct relaxations when analyzed in the impedance plane. These relaxations are attributed to the lumped grain and grain-boundary contributions in conjunction with a polarization effect at the electrode/sample interface. The admittance plane analysis revealed a semicircular relaxation in the low-frequency region, indicative of a trapping effect associated with grain-boundaries and the electrode/sample interface. The variation in the total electrical resistance with time is found to be dependent on the starting microstructure of the sample. A sample with a larger grain size shows a smaller degree of aging at elevated temperatures. Immittance measurements suggest that the major contribution to the aging behavior comes from the evolution in the microstructure. © 1995 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The thermoelectric properties near ambient temperature of half-Heusler alloys based on LnPdSb, where Ln=Ho, Er, and Dy are reported. The Seebeck coefficients are large, between 60 and 250 μV/K, and the materials are p type. The resistivities are between 0.6 and 20 mΩ cm. Thermal conductivities are between approximately 5.0 and 3.5 W/mK at 300 K, and are smallest in intentionally disordered materials. The highest ambient temperature ZT obtained is 0.06. Band-structure calculations are presented for LuPdSb. It is suggested that half-Heusler alloys with 18 electrons per formula unit may represent a large class of thermoelectric materials. © 1999 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

A novel approach to form low threshold laser structures, similar to existing mass-transported lasers but without the second regrowth step, is described. The laser has comparable performance in threshold current and quantum efficiency to more conventional buried heterostructure lasers made with a two-step process. Because of the simplicity in fabrication and its reduced parasitic capacitance it has the potential to be low cost and to have high modulation bandwidth.

Electronic Resource

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Objective To determine the effect of labour on free oxygen radical activity in the fetus, as reflected by lipid peroxide levels in umbilical cord arterial blood.Design Prospective, observational study.Setting Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong.Methods Umbilical cord arterial and venous blood samples were collected from singleton term infants delivered by elective caesarean section. Base excess, PO2, pCO2, and pH were measured in both samples and compared to identify double venous samples. Cord arterial acid-base balance and concentrations of organic hydroperoxides and malondialdehyde were compared with those obtained from normal vaginal deliveries.Results Cord arterial blood samples, obtained from cases of uncomplicated labour followed by spontaneous vaginal delivery, had significantly higher lipid peroxide concentrations than those delivered following elective caesarean section. This was most marked for malondialdehyde with a median value increased by 105%, whilst organic hydroperoxide was increased by only 27%. Of the acid-base parameters, base excess was increased by 78%, with only minimal changes in pH, PCO2, and PO2. These differences remained highly significant after including other pregnancy characteristics in multivariate analysis.Conclusion The findings indicate that high levels of free oxygen radical activity in the fetus are a function of the labour process, as are changes in acid-base balance.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Photoresponse signals with widths as short as 1.5 ps are observed from epitaxial YBa2Cu3O7−δ thin films using electro-optic sampling techniques. Voltage transients less than 2 ps wide are seen in 100- and 200-nm films exposed to 150-fs laser pulses and cooled to 79 K. At low bias currents, the amplitude of the fast response varies linearly with the bias current, suggesting a kinetic inductive mechanism. A negative transient about 15-ps long is also seen that may provide evidence for nonequilibrium recombination of excited quasiparticles into Cooper pairs. At high bias currents or large laser fluences, a fast tail with a decay time of about 10 ps appears in the response followed by a slow, resistive bolometric component due to sample heating. Nonequilibrium aspects of the photoresponse and the origin of the fast tail are discussed. © 1995 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The thermoelectric properties of intermetallic compounds with the Y3Au3Sb4 structure type, of formula Ln3Au3Sb4 for Ln=Gd, Nd, Ho, and Sm, are reported. The highest Seebeck coefficients are on the order of 100–200 μV/K, indicating that the dominant carriers are holes, and increase with increasing temperature. Variation of the Au:Sb ratio significantly affects the resistivities and Seebeck coefficients. Materials with mixtures of lanthanides on the large atom site show improved Seebeck coefficients without degradation of the electrical resistivity. The thermal conductivities are very low, even for the stoichiometric materials, and decrease in materials with mixed lanthanides. Band-structure calculations show a complex multivalley character for both valence and conduction bands. © 1999 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The electrical properties of CdTe and Cd1−xZnxTe crystals grown under excess tellurium by a modified Bridgman technique are critically dependent on the zinc content. Below an x value of 0.07, the as-grown CdZnTe crystals are n type while, above this value, CdZnTe crystals are p type. The origin of the shallow donor level at 0.01 eV below the conduction band is most likely singly ionized Te antisites (Te at Cd sites). The origin of the deep donor level at 0.75 eV below the conduction band is therefore doubly ionized tellurium antisites. Based on this model, the conduction type of CdZnTe crystals is determined by the results of compensation between the shallow donors of Te antisites and the shallow acceptors of Cd vacancies. High resistivity Cd0.9Zn0.1Te crystals are produced by compensating the p-type crystals with indium impurity at a low doping level of 1–5×1015 cm−3. At room temperature, CdZnTe radiation detectors can resolve the six low energy peaks in the 241Am spectrum, a performance comparable to that of the best CdZnTe detectors reported. © 2001 American Institute of Physics.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

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

Process Engineering, Biotechnology, Nutrition Technology

Any potential effects of postharvest freezing storage of beets on physicochemical characteristics of isolated pectin and beet pulp were determined. Fresh beets were stored at -20°for up to 3 mo. At the end of storage, beets were thawed and shredded, and sucrose was extracted. Pectin was isolated using a combination of enzyme treatment and acid extraction. Yield, galacturonic acid content, methoxyl ester content, and molecular mass distributions of the isolated pectin were determined. Neutral and acidic sugar compositions in the nonstarchy polysaccharides (NSP) of the beet pulp were determined using enzyme hydrolysis and gas chromatography. Results showed that physicochemical characteristics of isolated pectin, and sugar composition of the NSP in the beet pulp were not notably influenced by the freeze/thaw cycle.

Electronic Resource