We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in concentrations up to 10 13 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by applying gate voltage.

http://science.sciencemag.org/content/sci/306/5696/666.full.pdf

Electric Field Effect in Atomically Thin Carbon Films

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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。

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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

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.

http://science.sciencemag.org/content/sci/297/5582/787.full.pdf

Carbon Nanotubes--the Route Toward Applications

Mixed halide perovskites undergo phase segregation, manifested as spectral red-shifting of photoluminescence spectra under illumination. In the iodine-bromide mixed perovskites, the origin of the low-energy luminescence is related to iodine-enriched domains formation. Such domains create favorable bands for the induced carrier funneling into them. Despite the phase segregation process is crucial for mixed halide perovskite-based optoelectronics, numerous gaps exist within the understanding of this phenomenon. One such gap pertains to the emergence of temporary and intermediate photoluminescence peaks during the initial stages of phase segregation. However, these peaks appear only within the first few seconds of illumination. Nevertheless, the decreasing temperature may prolong these initial stages. In this work, we carry out a detailed study of the temperature dependence of anion segregation in MAPbBr_2I and MAPbBr2.5I0.5 halide perovskites, to obtain a deeper comprehension of segregation processes, particularly during their initial stages. The temporal evolution of low-temperature photoluminescence reveals the undergoing of the intermediate stage during the segregation process and temperature-related phase transition from orthorhombic to tetragonal phase. To complement the phase segregation study, the temperature dependence of time-resolved photoluminescence spectroscopy is provided, allowing us to estimate the change in the photoluminescence lifetimes for the initial and segregated peaks with temperature.

Temperature dependence of photo-induced phase segregation in bromide-rich mixed halide perovskites

Optoelectrochemical effect in thin polyphenylene films

A Reset MOSFET is added to a perovskite MOSFET-based photodetector to serve as a current source to mitigate the influence of ionic movement on the performance of the photodetector. With the added MOSFET, the hysteresis is significantly reduced, and the dark current is controllable. The on/off ratio resumes to 106 and an ultrasensitive responsivity (over 80, 000 A/W) is achieved under only 13 nW/cm2 red (665 nm) light intensity.

Introduction of a Reset MOSFET to Mitigate the Influence of Ionic Movement in Perovskite MOSFET Photodetector Measurements

Metal halide perovskites have emerged as promising gain materials for on-chip lasers in photonic integrated circuits (PICs). However, stable continuous wave (CW) lasing behavior under optical pumping at room temperature - a prerequisite for electrically pumped lasing - has not yet been demonstrated. To achieve stable CW operation, we introduce a multiplex of strategies that include morphological, structural and interfacial engineering of CH3NH3PbBr3 (MAPbBr3) thin films to improve perovskite's intrinsic stability, as well as high quality cavity design to reduce the operational power. We demonstrate for the first time, over 90-minute-long green CW lasing with 9.4W/cm2 threshold from a polycarbonate (PC)-defect-passivated, directly patterned MAPbBr3 two-dimensional photonic crystal (PhC) cavity without any substrate cooling. We also show our approach's effectiveness on the performance of MAPbBr3 under electrical excitation: we observe a seven-fold current efficiency enhancement by applying our strategies to a MAPbBr3 LED. This work paves the way to the realization of electrically pumped lasing in perovskites.

Anvar A. Zakhidov

Papers

Temperature dependence of photo-induced phase segregation in bromide-rich mixed halide perovskites

Optoelectrochemical effect in thin polyphenylene films

Introduction of a Reset MOSFET to Mitigate the Influence of Ionic Movement in Perovskite MOSFET Photodetector Measurements

Environmentally Stable Room Temperature Continuous Wave Lasing in Defect-passivated Perovskite

Perovskite solar cells with ZnS as electron transport layer