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.

Gradient SiNO anti-reflective layers in solar selective coatings

Abstract: A solar selective coating includes a substrate, a cermet layer having nanoparticles therein deposited on the substrate, and an anti-reflection layer deposited on the cermet layer. The cermet layer and the anti-reflection layer may each be formed of intermediate layers. A method for constructing a solar-selective coating is disclosed and includes preparing a substrate, depositing a cermet layer on the substrate, and depositing an anti-reflection layer on the cermet layer.

Low-Temperature Thermoelectric Materials

Abstract: Bismuth (Bi), Antimony (Sb), and the Bi–Sb alloys form a complete class of thermoelectric semiconductors that are particularly suited to thermoelectric applications below room temperature. Large thermal conductivity suppression by nanostructuring at low temperature is much more significant than any other nanostructured thermoelectric materials at high temperatures. This chapter discusses the current status of research on low-temperature thermoelectric materials and the thermoelectric properties of some rare earth (RE) alloys that we think will be a good direction for research to bring thermoelectric cryogenic cooling into a reality. More research into other materials may be required, rather than focusing only on heavily doped semiconductor thermoelectric materials. The other research directions points toward Kondo materials. The investigation of RE alloys could be a good direction to bring thermoelectric cryogenic cooling toward reality. These materials need further study and optimization to make them practical for applications.

Metallic Nanowire Networks: Transparent Nanowire Network Electrode for Textured Semiconductors (Small 5/2013)

Abstract: This work presents an inexpensive and easily manufacturable, highly conductive and transparent nanowire network electrode for textured semiconductors. It is based on lines of silver nanoparticles transformed into a nanowire network by microwave or furnace sintering. The nanonetwork electrode on crystalline silicon is demonstrated experimentally, with the nanoparticles self-assembling in the valleys between the pyramids of the textured surface. Optical experiments show that this conductive nanowire network electrode can be essentially ‘invisible’ when covered with the conventional anti-refl ection coating (ARC), and thus could be employed in photovoltaic applications.

THERMOELECTRIC COMPOSITIONS AND METHODS OF FABRICATING HIGH THERMOELECTRIC PERFORMANCE MgAgSb-BASED MATERIALS

Abstract: Systems and methods of manufacturing a thermoelectric, high performance material by using ball-milling and hot pressing materials according to various formulas, where some formulas substitute a different element for part of one of the elements in the formula, in order to obtain a figure of merit (ZT) suitable for thermoelectric applications.

Synthesis, Characterization and Thermal Stability of Highly Crystallized Titania Nanotubes

Abstract: Gram quantities of titania (TiO2) nanotubes, with typical outside diameter about 9 nm, wall thickness about 2.5 nm, and length about 600 nm, were synthesized from anatase nano- and micro-powder using the hydrothermal method. The crystallization, structure, and phase stability of the nanotubes at high temperatures were systematically studied. A morphology change from nanotube to nanowire was observed at 650°C. The as-prepared nanotubes were usually contaminated with sodium impurities, other TiO2-derived phases and were poorly crystallized, but under optimized synthesis conditions the impurity phases was completely removed, resulting in highly crystallized pure nanotubes. The volume filling fraction of the autoclave as well as the concentration of the acid treatment were found to be particularly important for controlling the purity and crystallinity of the resulting nanotubes.

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.