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

Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

The Chemistry and Applications of Metal-Organic Frameworks

Mobility — the transport of people and goods — is a socioeconomic reality that will surely increase in the coming years. It should be safe, economic and reasonably clean. Little energy needs to be expended to overcome potential energy changes, but a great deal is lost through friction (for cars about 10 kWh per 100 km) and low-efficiency energy conversion. Vehicles can be run either by connecting them to a continuous supply of energy or by storing energy on board. Hydrogen would be ideal as a synthetic fuel because it is lightweight, highly abundant and its oxidation product (water) is environmentally benign, but storage remains a problem. Here we present recent developments in the search for innovative materials with high hydrogen-storage capacity.

/pdf/hydrogen-storage-materials-for-mobile-applications-2dxdlm86hm.pdf

Hydrogen-storage materials for mobile applications

This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).

/pdf/cellulose-nanomaterials-review-structure-properties-and-2z8x922p3v.pdf

Cellulose nanomaterials review: structure, properties and nanocomposites

[Liu, Chang; Li, Feng; Ma, Lai-Peng; Cheng, Hui-Ming] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China.;Cheng, HM (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Peoples R China;cheng@imr.ac.cn

Advanced Materials for Energy Storage

Screen-printing provides an economically attractive means for making Ag electrical contacts to Si solar cells, but the use of Ag substantiates a significant manufacturing cost, and the glass frit used in the paste to enable contact formation contains Pb. To achieve optimal electrical performance and to develop pastes with alternative, abundant and non-toxic materials, a better understanding the contact formation process during firing is required. Here, we use in situ X-ray diffraction during firing to reveal the reaction sequence. The findings suggest that between 500 and 650 °C PbO in the frit etches the SiNx antireflective-coating on the solar cell, exposing the Si surface. Then, above 650 °C, Ag(+) dissolves into the molten glass frit - key for enabling deposition of metallic Ag on the emitter surface and precipitation of Ag nanocrystals within the glass. Ultimately, this work clarifies contact formation mechanisms and suggests approaches for development of inexpensive, nontoxic solar cell contacting pastes.

/pdf/the-formation-mechanism-for-printed-silver-contacts-for-1w0z2rpbgg.pdf

The formation mechanism for printed silver-contacts for silicon solar cells

Screen-printing provides an economically attractive means for making Ag electrical contacts to Si solar cells, but the use of Ag substantiates a significant manufacturing cost, and the glass frit used in the paste to enable contact formation contains Pb. To achieve optimal electrical performance and to develop pastes with alternative, abundant and non-toxic materials, a better understanding the contact formation process during firing is required. Here, we use in situ X-ray diffraction during firing to reveal the reaction sequence. The findings suggest that between 500 and 650 °C PbO in the frit etches the SiNx antireflective-coating on the solar cell, exposing the Si surface. Then, above 650 °C, Ag+ dissolves into the molten glass frit – key for enabling deposition of metallic Ag on the emitter surface and precipitation of Ag nanocrystals within the glass. Ultimately, this work clarifies contact formation mechanisms and suggests approaches for development of inexpensive, nontoxic solar cell contacting pastes.

http://astro1.panet.utoledo.edu/~mheben/PDF/controlling_single_walled_nanotube_m_heben_(2000)_chem_phys_lett.pdf

Controlling single-wall nanotube diameters with variation in laser pulse power

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work we developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be ~ 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. We also made significant advances in the synthesis of SWNT materials by turning to a laser-vaporization method rather than the arc-generation method employed previously. In addition, we began to develop methods to purify nanotubes and cut nanotubes into shorter segments. This year we have made further advances in the development of our laser synthesis technique, and we now generate crude material containing 20-30 wt% SWNTs at a rate of ~150 mg / hr or ~ 1.5 g / day. In addition we have perfected a very simple 3-step purification process which results in material that is > 98 wt% pure which is the purest reported to date. In conjunction with the purification method we pioneered a thermal gravimetric analysis (TGA) technique which enables accurate determination of SWNT wt% contents in carbon soot. Finally, we have simplified our previous nanotube cutting technique and have developed a process that allows for highly reproducible cutting of our purified laser-generated materials. The new cutting method enables the opening of laser-produced tubes which were unreactive to the oxidation methods that successfully opened our previously synthesized arc-generated tubes, and offers a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. Most importantly, this year we have demonstrated that purified cut SWNTs adsorb between 3.5 ‐ 4.5 wt% hydrogen under ambient conditions in several minutes and that the adsorbed hydrogen is effectively “capped” by CO 2 making it stable for weeks in atmospheric conditions.

/pdf/carbon-nanotube-materials-for-hydrogen-storage-1kyn3ox6ye.pdf

Carbon nanotube materials for hydrogen storage

Metal–insulator–metal (MIM) structures are gaining signifi cant attention due to their applications in varied electronic devices such as rectennas for energy harvesting, [ 1–4 ] high-frequency detectors/infrared photo-detection, [ 5–7 ] high-frequency mixers, [ 8–10 ] as well as applications in static memory and switching devices. [ 11 , 12 ] Ideally, for most of these applications, the MIM structure should exhibit current–voltage ( I–V ) characteristics with high asymmetry ( f ASYM > 1), strong nonlinearity ( f NL > 3), fast responsivity ( f RES > 7 V − 1 ), low hysteresis and low turn-on voltage (close to zero bias). [ 3 ] Despite the widespread utility and simple architecture of MIM devices, there is a signifi cant lack of understanding as to which materials properties produce the desired device performance. Although it is commonly stated that a high work-function difference ( Δ φ ) between the metal electrodes is responsible for high f ASYM and f NL , [ 3 , 5 , 7 ]

Philip A. Parilla

Papers

The formation mechanism for printed silver-contacts for silicon solar cells

The formation mechanism for printed silver-contacts for silicon solar cells

Controlling single-wall nanotube diameters with variation in laser pulse power

Carbon nanotube materials for hydrogen storage

Fabrication and Characterization of MIM Diodes Based on Nb/Nb2O5 Via a Rapid Screening Technique