Zhifeng Ren

Bio: Zhifeng Ren is an academic researcher from Texas Center for Superconductivity. The author has contributed to research in topics: Thermoelectric effect & Thermoelectric materials. The author has an hindex of 122, co-authored 695 publications receiving 71212 citations. Previous affiliations of Zhifeng Ren include Massachusetts Institute of Technology & University of Cincinnati.

Thermodynamic calculation and its experimental correlation with the growth process of boron arsenide single crystals

Abstract: The reported high thermal conductivity of boron arsenide (BAs) has prompted scientists to characterize the various properties of this material. Thermodynamic data for the enthalpy (H), entropy (S), and Gibbs free energy (G) of BAs were previously predicted from theory. Here, its thermodynamic properties were determined from experimental measurements of its heat capacity (CP) over the temperature range of 298 to 1150 K and compared with the predicted data. The thermodynamic properties of BAs at 800 K were calculated to be H = − 8.6 kJ mo l − 1, S = 81.0 J mo l − 1 K − 1, and G = − 73.4 kJ mo l − 1, and we found that its formation reaction becomes endothermic at 984 K. We also analyzed the experimental findings from growing a BAs single crystal (SC) by the chemical vapor transport (CVT) method. Thermodynamic concepts were applied to show that iodine is the most suitable transport agent among the halogens for obtaining BAs SC by CVT. Additionally, three different combinations of precursors were employed during BAs SC growth by CVT. The three approaches are described in terms of differences in partial pressure of a gaseous species, and their results are compared for possible optimization of the BAs SC growth process by CVT.

Interfacial Superconductivity Achieved in Parent AEFe2As2 (AE = Ca, Sr, Ba) by a Simple and Realistic Annealing Route.

Abstract: Materials with interfaces often exhibit extraordinary phenomena exemplified by rich physics, such as high-temperature superconductivity and enhanced electronic correlations. However, demonstrations...

Pairing symmetry in single-layer tetragonal Tl2Ba2CuO6+δ from in-plane torque anisotropy

Abstract: The in-plane torque anisotropy of the high- T c cuprate Tl 2 Ba 2 CuO 6+δ gives evidence of a mixed s + d pairing state allowed by the possible breaking of its tetragonal symmetry at low temperature. The validity of our result is supported by the absence of any in-plane anisotropy in the classical superconductors NbN and the layered 2H-NbSe 2 measured under the same conditions.

Orientation control of graphene flakes by magnetic field: broad device applications of macroscopically aligned graphene

Abstract: Owing to a large diamagnetism, graphene flakes can respond and be aligned to magnetic field like a ferromagnetic material. Aligned graphene flakes exhibit emergent properties approaching single-layer graphene. Anisotropic optical properties also give rise to a magnetic writing board using graphene suspension and a bar magnet as a pen. This simple alignment technique opens up enormous applications of graphene.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Carbon Nanotubes--the Route Toward Applications

Abstract: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.