Search Results - (Author, Cooperation:K. Xia)

2018-01-20

American Physical Society (APS)

1098-0121

1095-3795

Physics

Structure, structural phase transitions, mechanical properties, defects

2018-06-23

American Association for the Advancement of Science (AAAS)

2375-2548

Natural Sciences in General

2018-01-20

American Physical Society (APS)

0031-9007

1079-7114

Physics

Nonlinear Dynamics, Fluid Dynamics, Classical Optics, etc.

2011-04-01

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Cell Line ; Chromatin/metabolism ; CpG Islands/genetics ; Cytosine/analogs & derivatives/metabolism ; *DNA Methylation ; DNA-Binding Proteins/*metabolism ; Embryonic Stem Cells/*metabolism ; Gene Expression Regulation, Developmental ; *Gene Silencing ; Genome/genetics ; Mice ; Polycomb-Group Proteins ; Promoter Regions, Genetic/genetics ; Proto-Oncogene Proteins/*metabolism ; Repressor Proteins/metabolism ; *Transcription, Genetic

2018-01-06

American Association for the Advancement of Science (AAAS)

2375-2548

Natural Sciences in General

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Measurements of the capillary length in phase-separated solutions of polymethylmethacrylate in 3-octanone (PMMA/3-OCT) for each of five different molecular weights of PMMA, and in phase-separated solutions of polystyrene in methylcyclohexane (PS/MCH) for a single molecular weight of polymer, are reported. Measurements on PMMA/3-OCT were by the sessile-drop method; those on PS/MCH were by both the sessile-drop and capillary-rise methods. Interfacial tensions are estimated from estimated density differences and the measured capillary lengths. A theoretically predicted scaling law for the dependence of capillary length on polymer molecular weight and temperature is tested and at least semiquantitatively verified. As by-products of the sample preparation, the molecular-weight dependences of the critical composition and critical solution temperature of PMMA/3-OCT were also determined. The volume fraction of polymer at the critical point, φc, is found to be proportional to the −0.37±0.01 power of the molecular weight, in agreement with values of this exponent found by others for polystyrene solutions.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

A new light scattering method is developed to measure scattering amplitude fluctuations resulting from either internal motions of flexible macromolecules or rotations of rigid particles. With a single-beam two-color cross-correlation scheme, the technique becomes insensitive to rapid phase fluctuations of the scattered light produced by translational motions of the scattering particles. We frame the scattering theory so as to encompass rotations and number fluctuations of small particles in a steady laminar flow. Experiment verifies the theory and demonstrates its applications. The technique can be used to measure the magnitudes of the local velocity and the flow vorticity. It can also be used to measure internal motions and shape fluctuations of flexible macromolecules. The advantages of the technique are its high spatial resolution, fast temporal response, and ease of use.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The dependences of magneto-optical effect, effective optical constants, and giant magnetoresistance (GMR) on the thickness of Cu layers were investigated in NiCo/Cu multilayers prepared by rf magnetron sputtering. A peak of saturation polar Kerr rotation θK, occurred simultaneously with that of GMR ratio when the Cu thickness is around 1.0 nm, where a clear drop of the effective optical constants n and k appeared. The peak of θK is mainly caused by the reduction of the effective optical constants, which dominate over the small drop of the effective off-diagonal elements of the dielectric tensor. The concurrent variation of GMR and θK is related to antiferromagnetic interlayer coupling, which may change the electron band structure and thus the optical and magneto-optical transitions of electrons. © 1998 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Measurements of the coexistence curves for phase-separated polymer solutions of polymethylmethacrylate in 3-octanone (PMMA/3-OCT) for six different molecular weights of PMMA have been carried out. We have tested the scaling behavior of the order parameter Δφ (the difference between polymer volume fractions in the two coexisting phases) for its dependence on the degree of polymerization N of the polymer chains and the reduced temperature ε=(Tc−T)/Tc. The experiments reveal that, in the asymptotic regime, the measured order parameter has power-law dependence on both N and ε, i.e., Δφ=3.8N−0.21ε0.34. Furthermore, when the symmerization procedure of Sanchez [J. Appl. Phys. 58, 2871 (1985)] is used to analyze the data, it suggests that εN0.46 may be used as a scaling variable for phase separated polymer solutions. © 1996 American Institute of Physics.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

After exposure to a doubled CO2 concentration of 750 µL L−1 for 2 months, average relative growth rate (RGR) of Mokara Yellow increased 25%. The two carboxylating enzymes, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase), responded differently to CO2 enrichment. There was a significant daytime down-regulation in Rubisco activity in the leaves of CO2-enriched plants. However, PEPCase activity in CO2-enriched plants was much higher in the dark period, although it was slightly lower during the daytime than that at ambient CO2. Leaf sucrose–phosphate synthase (SPS) and sucrose synthase (SS) activities in CO2-enriched plants increased markedly, along with a night-time increase in total titratable acidity and malate accumulation. There was a remarkable increase in the levels of indole-3-acetic acid (IAA), gibberellins A1 and A3 (GA1+3), isopentenyladenosine (iPA) and zeatin riboside (ZR) in the expanding leaves of plants grown at elevated CO2. It is suggested that (1) the down-regulation of Rubisco and up-regulation of SPS and SS are two important acclimation processes that are beneficial because it enhanced both photosynthetic capacity at high CO2 and reduced resource investment in excessive Rubisco capacity; (2) the increased levels of plant hormones in CO2-enriched M. Yellow might play an important role in controlling its growth and development.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background  Our previous study has identified two loci for disseminated superficial actinic porokeratosis (DSAP), but the genes responsible are still unknown.Objectives  To narrow down the candidate regions and to assess candidate genes.Methods  A genome-wide scan and linkage analysis were carried out in a newly collected five-generation Chinese family with DSAP. In addition, six candidate genes were screened for possible DSAP-associated mutations.Results  DSAP in this family was associated with chromosome 12q. Fine mapping and haplotype construction refined the DSAP1 locus to a 4·4-cM interval. No disease-associated mutation was detected in CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 or KIAA0789 genes.Conclusions  The DSAP1 locus was localized to a 4·4-cM interval at chromosome 12q23.2-24.1. CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 and KIAA0789 genes were not associated with DSAP1.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Summary Background Disseminated superficial actinic porokeratosis (DSAP) is a chronic cutaneous disorder characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. It develops in teenagers in sun-exposed areas of skin and usually follows an autosomal dominant inheritance pattern. The first locus for DSAP was localized to chromosome 12q23.2–24.1, but no gene responsible for porokeratosis has been identified to date. Objectives To determine whether DSAP is a genetically heterogeneous disorder and to identify the disease gene locus in a three-generation Chinese family with DSAP. Methods Genetic linkage analysis was carried out in this family using 15 microsatellite markers between D12S1671 and D12S369 on chromosome 12q, followed by a genome-wide scan with 382 microsatellite markers from the autosomes. Results Genetic linkage analysis with chromosome 12q markers suggested that the locus in this family is not linked to chromosome 12q. A genome-wide scan and fine mapping finally localized the locus for DSAP in this family to a 6.4-cM region between markers D15S1023 and D15S1030 at chromosome 15q25.1–26.1. This DSAP locus was named DSAP2. Conclusions The previous results and this study have shown that DSAP is a genetically heterogeneous disorder; a novel locus for DSAP, termed DSAP2, was mapped to a 6.4-cM region between markers D15S1023 and D15S1030.

Electronic Resource

0038-1098

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0375-9474

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

1573-4811

Springer Online Journal Archives 1860-2000

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

Electronic Resource

1434-6036

PACS. 47.27.Te Convection and heat transfer – 44.25.+f Natural convection

Springer Online Journal Archives 1860-2000

Physics

Abstract: An experimental study of Rayleigh-Bénard turbulent convection in a cubic cell is presented. We measure the mean temperature profiles, the root mean square (RMS) temperature profiles and the thermal boundary layer thickness for various values of the Rayleigh number Ra and at various positions x along the direction of large-scale circulation (LSC), using water as the working fluid. The scaled mean temperature profiles measured at the same Ra but different x are found to be self-similar, but those measured at different Ra do not show a universal form. In contrast, RMS temperature profiles measured at the same position but different Ra appear to show an invariant form, whereas those with different x but of the same Ra could not be scaled onto a single curve. Irrespective of the measuring positions and Ra, the RMS profiles show a peak value around the boundary layer thickness, and their gradients at bottom surface increase monotonically in the direction of LSC and with increasing Ra.

Electronic Resource

1435-0661

Springer Online Journal Archives 1860-2000

Geosciences

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

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

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

Abstract The rare earth element cerium (Ce) was added to cast binary Ti-44 at.% Al alloys by arc melting in the range of 0.05 to 0.3 atomic percent. It was observed that the as-cast structures of the ingots consisted of the usual three zones of fine equiaxed grains near the mould wall, columnar grains growing away from the mould wall and coarse equiaxed grains near the center. Ce greatly promoted the growth of columnar grains and reduced their diameters. The ingots were subsequently heat treated to obtain well-defined fully lamellar structures. The material containing no rare earth displayed large equiaxed lamellar colonies of average size of 〉1400 μm; the material with 0.05 at.% addition of Ce consisted of lamellar colonies of as fine as ∼440 μm. The finest grain size of this material was 320 μm at the top position in the ingot.

Electronic Resource