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.

Aligned Carbon Nanotubes : Physics, Concepts, Fabrication and Devices

Abstract: Introduction to Carbon.- Introduction to Carbon Nanotubes.- Growth Techniques of Carbon Nanotubes.- Chemical Vapor Deposition of Carbon Nanotubes.- Physics of Direct Current Plasma-Enhanced Chemical Vapor Deposition.- Technologies to Achieve Carbon Nanotube Alignment.- Measurement Techniques of Aligned Carbon Nanotubes.- Properties and Applications of Aligned Carbon Nanotube Arrays.- Potential Applications of Carbon Nanotube Arrays.

Field emission from few-layer graphene nanosheets produced by liquid phase exfoliation of graphite.

Abstract: Graphene nanosheets have been synthesized from commercial expandable graphite by heating in a microwave oven and dispersing in ethanol by ultrasonication. Scanning and transmission electron microscopy and electron energy-loss spectroscopy and atomic force microscope showed that the nanosheets were about 2 nm in thickness and 10 microm in diameter. The field emission of the graphene sheets has been investigated. An emission current density of 1 mA/cm2 has been achieved at an electric field of 3.7 V/microm with a turn-on field of 1.7 V/microm at 0.01 mA/cm2. The annealing of the samples at 400 degrees C in vacuum greatly improved the field emission performance.

Metal-doped semiconductor nanoparticles and methods of synthesis thereof

Abstract: The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

Hybrid structure of pH-responsive hydrogel and carbon nanotube array with superwettability

Abstract: We report an all-dry fabrication method of the hybrid structure of pH-responsive hydrogel and carbon nanotube arrays using initiated chemical vapor deposition (iCVD). Vertically aligned carbon nanotube (VACNT) arrays with low site density were coated by a vapor-deposited poly(methacrylic acid-co-ethylene glycol diacrylate) hydrogel with complete retention of the aligned structure and precise control of the coating thickness on each nanotube. The hydrogel coating imparted pH-responsiveness to the nanotube arrays and significantly enhanced the surface wettability. With an ultrathin 50 nm hydrogel coating, the hybrid hydrogel–VACNT array structure exhibited superwettability in neutral buffer solutions, which was attributed to the synergistic effect of the structure porosity and the ionization of the pH-responsive hydrogel. Under the acidic condition, the wettability depended on the coating thickness, and the apparent contact angle of the hybrid structure was in agreement with the calculated results from the Cassie–Baxter model.

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.