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

Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.

Graphene-Based Materials: Synthesis, Characterization, Properties, and Applications

Transparent electrodes are a necessary component in many modern devices such as touch screens, LCDs, OLEDs, and solar cells, all of which are growing in demand. Traditionally, this role has been well served by doped metal oxides, the most common of which is indium tin oxide, or ITO. Recently, advances in nano-materials research have opened the door for other transparent conductive materials, each with unique properties. These include CNTs, graphene, metal nanowires, and printable metal grids. This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano-material coatings. Electronic, optical, and mechanical properties of each material will be discussed, as well as suitability for various applications.

Emerging Transparent Electrodes Based on Thin Films of Carbon Nanotubes, Graphene, and Metallic Nanostructures

Reproducible dry and wet transfer techniques were developed to improve the transfer of large-area monolayer graphene grown on copper foils by chemical vapor deposition (CVD). The techniques reported here allow transfer onto three different classes of substrates: substrates covered with shallow depressions, perforated substrates, and flat substrates. A novel dry transfer technique was used to make graphene-sealed microchambers without trapping liquid inside. The dry transfer technique utilizes a polydimethylsiloxane frame that attaches to the poly(methyl methacrylate) spun over the graphene film, and the monolayer graphene was transferred onto shallow depressions with 300 nm depth. The improved wet transfer onto perforated substrates with 2.7 μm diameter holes yields 98% coverage of holes covered with continuous films, allowing the ready use of Raman spectroscopy and transmission electron microscopy to study the intrinsic properties of CVD-grown monolayer graphene. Additionally, monolayer graphene transfer...

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Transfer of CVD-Grown Monolayer Graphene onto Arbitrary Substrates

Since its debut in 2004, graphene has attracted enormous interest because of its unique properties. Chemical vapor deposition (CVD) has emerged as an important method for the preparation and production of graphene for various applications since the method was first reported in 2008/2009. In this Account, we review graphene CVD on various metal substrates with an emphasis on Ni and Cu. In addition, we discuss important and representative applications of graphene formed by CVD, including as flexible transparent conductors for organic photovoltaic cells and in field effect transistors.Growth on polycrystalline Ni films leads to both monolayer and few-layer graphene with multiple layers because of the grain boundaries on Ni films. We can greatly increase the percentage of monolayer graphene by using single-crystalline Ni(111) substrates, which have smooth surface and no grain boundaries. Due to the extremely low solubility of carbon in Cu, Cu has emerged as an even better catalyst for the growth of monolayer ...

Review of chemical vapor deposition of graphene and related applications.

We report a comparative study and Raman characterization of the formation of graphene on single crystal Ni (111) and polycrystalline Ni substrates using chemical vapor deposition (CVD). Preferential formation of monolayer/bilayer graphene on the single crystal surface is attributed to its atomically smooth surface and the absence of grain boundaries. In contrast, CVD graphene formed on polycrystalline Ni leads to a higher percentage of multilayer graphene (≥3 layers), which is attributed to the presence of grain boundaries in Ni that can serve as nucleation sites for multilayer growth. Micro-Raman surface mapping reveals that the area percentages of monolayer/bilayer graphene are 91.4% for the Ni (111) substrate and 72.8% for the polycrystalline Ni substrate under comparable CVD conditions. The use of single crystal substrates for graphene growth may open ways for uniform high-quality graphene over large areas.

Comparison of Graphene Growth on Single-Crystalline and Polycrystalline Ni by Chemical Vapor Deposition

[*] Prof. Y. Yang, V. C. Tung, Z. Xu, L.-M. Chen, Prof. R. B. Kaner Department of Materials Science and Engineering and California NanoSystem Instute University of California, Los Angeles Los Angeles, CA 90095 (USA) E-mail: yangy@ucla.edu M. J. Allen, K. S. Nelson, Prof. R. B. Kaner Department of Chemistry and Biochemistry and California NanoSystems Institute University of California Los Angeles, Los Angeles, CA 90095 (USA)

Soft Transfer Printing of Chemically Converted Graphene

Massive aligned carbon nanotubes hold great potential but also face significant integration/assembly challenges for future beyond-silicon nanoelectronics. We report a wafer-scale processing of aligned nanotube devices and integrated circuits, including progress on essential technological components such as wafer-scale synthesis of aligned nanotubes, wafer-scale transfer of nanotubes to silicon wafers, metallic nanotube removal and chemical doping, and defect-tolerant integrated nanotube circuits. We have achieved synthesis of massive aligned nanotubes on complete 4 in. quartz and sapphire substrates, which were then transferred to 4 in. Si/SiO2 wafers. CMOS analogous fabrication was performed to yield transistors and circuits with features down to 0.5 μm, with high current density ∼20 μA/μm and good on/off ratios. In addition, chemical doping has been used to build fully integrated complementary inverter with a gain ∼5, and a defect-tolerant design has been employed for NAND and NOR gates. This full-wafer...

CMOS-Analogous Wafer-Scale Nanotube-on-Insulator Approach for Submicrometer Devices and Integrated Circuits Using Aligned Nanotubes

We report high-performance fully transparent thin-film transistors (TTFTs) on both rigid and flexible substrates with transfer printed aligned nanotubes as the active channel and indiumtin oxide as the source, drain, and gate electrodes. Such transistors have been fabricated through low-temperature processing, whichalloweddevicefabricationevenonflexiblesubstrates.Transparenttransistorswithhigheffectivemobilities (1300 cm 2 V 1 s 1 ) were first demonstrated on glass substrates via engineering of the source and drain contacts, and high on/off ratio (310 4 ) was achieved using electrical breakdown. In addition,flexible TTFTs withgoodtransparencywerealsofabricatedandsuccessfullyoperatedunderbendingupto120°.Allofthedevices showed good transparency (80% on average). The transparent transistors were further utilized to construct a fully transparent andflexible logic inverter on a plastic substrate and also used to control commercial GaN light- emitting diodes (LEDs) with light intensity modulation of 10 3 . Our results suggest that aligned nanotubes have great potential to work as building blocks for future transparent electronics.

Transparent Electronics Based on Transfer Printed Aligned Carbon Nanotubes on Rigid and Flexible

Coexistence of metallic and semiconducting carbon nanotubes in as-grown samples sets important limits to their application in high-performance electronics. We present the metal-to-semiconductor conversion of carbon nanotubes for field-effect transistors based on both aligned nanotubes and individual nanotube devices. The conversion process is induced by light irradiation, scalable to wafer-size scales and capable of yielding improvements in the channel-current on/off ratio up to 5 orders of magnitude in nanotube-based field-effect transistors. Inactivation of metallic nanotubes in the channels was achieved as a consequence of a diameter-dependent photochemical process that led to a controlled oxidation of the nanotube sidewall and, hence, stronger localization of π-electrons. Optimization of irradiation conditions yields nearly 90% of depletable nanotube field-effect transistors.

Lewis Gomez

Papers

Comparison of Graphene Growth on Single-Crystalline and Polycrystalline Ni by Chemical Vapor Deposition

Soft Transfer Printing of Chemically Converted Graphene

CMOS-Analogous Wafer-Scale Nanotube-on-Insulator Approach for Submicrometer Devices and Integrated Circuits Using Aligned Nanotubes

Transparent Electronics Based on Transfer Printed Aligned Carbon Nanotubes on Rigid and Flexible

Scalable Light-Induced Metal to Semiconductor Conversion of Carbon Nanotubes