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

The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

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The chemistry of graphene oxide

An improved method for the preparation of graphene oxide (GO) is described. Currently, Hummers’ method (KMnO4, NaNO3, H2SO4) is the most common method used for preparing graphene oxide. We have found that excluding the NaNO3, increasing the amount of KMnO4, and performing the reaction in a 9:1 mixture of H2SO4/H3PO4 improves the efficiency of the oxidation process. This improved method provides a greater amount of hydrophilic oxidized graphene material as compared to Hummers’ method or Hummers’ method with additional KMnO4. Moreover, even though the GO produced by our method is more oxidized than that prepared by Hummers’ method, when both are reduced in the same chamber with hydrazine, chemically converted graphene (CCG) produced from this new method is equivalent in its electrical conductivity. In contrast to Hummers’ method, the new method does not generate toxic gas and the temperature is easily controlled. This improved synthesis of GO may be important for large-scale production of GO as well as the ...

https://www.researchgate.net/file.PostFileLoader.html?id=54ca19b4cf57d79a768b4618&assetKey=AS%3A273691751976961%401442264606356

Improved Synthesis of Graphene Oxide

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential lies in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultrawideband tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light-emitting devices to touch screens, photodetectors and ultrafast lasers. Here we review the state-of-the-art in this emerging field.

/pdf/graphene-photonics-and-optoelectronics-3ddg6ukzcu.pdf

Graphene photonics and optoelectronics

Presolar Al-, Ca-, and Ti-rich Oxide Grains in the Krymka Meteorite

Presolar Chromite in Orgueil

/pdf/stardust-material-in-the-paired-enstatite-chondrites-sah-2e17yt13w8.pdf

Stardust material in the paired enstatite chondrites: SAH 97096 and SAH 97159

Lack of Evidence for In Situ Decay of Aluminum-26 in Comet 81P/Wild 2 CAI-like Refractory Particles 'Inti' and 'Coki'

Introduction: Other than nanodiamonds, silicates are the most abundant circumstellar condensate grains found in meteorites and interplanetary dust particles [1]. Laboratory analyses of these grains can provide complementary information to telescope-based IR-spectroscopy studies of grains in circumstellar disks, as well as inform our understanding of the circumstel-lar condensation process. The 10-micron region of the IR spectra of most circumstellar disks appears devoid of sharp features, which is consistent with a predominance of amorphous grains [2]. However, crystalline fractions above 50% have been estimated for some disks [3]. Previous transmission electron microscopy studies of circumstellar silicates are limited to ~ 18 grains in total, of which 4 were olivine [4-7], 1 a me-tastable grain with a perovskite-like structure and py-roxene composition [8], and the remainder amorphous to finely nanocrystalline [6, 9-12]. The laboratory analysis and astronomical observations appear to be in general agreement over the predominance of amorphous grains. However, further work is needed to understand whether the laboratory data are biased by choice of host meteorite, targeting of larger grains, or other effects, and to look for signatures of post-condensation processes, such as radiation or grain-grain collisions effects. By performing coordinated analysis of in situ silicates in primitive meteorites using secondary ion mass spectrometry for isotopic identification , Auger electron spectroscopy for high-spatial resolution surface composition measurements, and transmission electron microscopy (TEM) for structure and cross-section composition measurements, we aim to address the range of circumstellar dust primary mi-crostructures and elemental compositions, and any correlation with the type of progenitor star. Here we report TEM analysis of two grains from the MET 00426 CR3 chondrite, previously characterized by NanoSIMS and Auger spectroscopy [13]. Experimental: We targeted three grains identified as isotopically anomalous for focused ion beam lift-out and subsequent TEM study. The isotopic compositions of the grains were measured using the Cameca NanoSIMS at Washington University. Elemental spectra of the surface of these grains were obtained with the Washington University Auger Nanoprobe, and quantified based on sensitivity factors for olivine and pyroxene standards.

Frank J. Stadermann

Papers

Presolar Al-, Ca-, and Ti-rich Oxide Grains in the Krymka Meteorite

Presolar Chromite in Orgueil

Stardust material in the paired enstatite chondrites: SAH 97096 and SAH 97159

Lack of Evidence for In Situ Decay of Aluminum-26 in Comet 81P/Wild 2 CAI-like Refractory Particles 'Inti' and 'Coki'

Structure, Elemental Composition and Isotopic Composition of Presolar Silicates in MET 00426