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 …

I and i

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

http://utw10193.utweb.utexas.edu/Archive/RuoffsPDFs/160.pdf

Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide

Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce highly ordered, two-dimensional hexagonal (space group p6mm) silica-block copolymer mesophases. Calcination at 500°C gives porous structures with unusually large interlattice d spacings of 74.5 to 320 angstroms between the (100) planes, pore sizes from 46 to 300 angstroms, pore volume fractions up to 0.85, and silica wall thicknesses of 31 to 64 angstroms. SBA-15 can be readily prepared over a wide range of uniform pore sizes and pore wall thicknesses at low temperature (35° to 80°C), using a variety of poly(alkylene oxide) triblock copolymers and by the addition of cosolvent organic molecules. The block copolymer species can be recovered for reuse by solvent extraction with ethanol or removed by heating at 140°C for 3 hours, in both cases, yielding a product that is thermally stable in boiling water.

Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores

Battery technologies involving Li-S chemistries have been touted as one of the most promising next generation systems. The theoretical capacity of sulfur is nearly an order of magnitude higher than current Li-ion battery insertion cathodes and when coupled with a Li metal anode, Li-S batteries promise specifi c energies nearly fi ve-fold higher. However, this assertion only holds if sulfur cathodes could be designed in the same manner as cathodes for Li-ion batteries. Here, the recent efforts to engineer high capacity, thick, sulfur-based cathodes are explored. Various works are compared in terms of capacity, areal mass loading, and fraction of conductive additive, which are the critical parameters dictating the potential for a device to achieve a specifi c energy higher than current Li-ion batteries (i.e., >200 Wh kg −1 ). While an inferior specifi c energy is projected in the majority of cases, several promising strategies have the potential to achieve >500 Wh kg −1 . The challenges associated with the limited cycle-life of these systems due to both the polysulfi de shuttle phenomenon and the rapid degradation of the Li metal anode that is experienced at the current densities required to charge high specifi c energy batteries in a reasonable timeframe are also discussed.

/pdf/structural-design-of-cathodes-for-li-s-batteries-2u74ycuaml.pdf

Structural Design of Cathodes for Li-S Batteries

Carbon-supported precious metal catalysts are widely used in heterogeneous catalysis and electrocatalysis, and enhancement of catalyst dispersion and stability by controlling the interfacial structure is highly desired. Here we report a new method to deposit metal oxides and metal nanoparticles on graphene and form stable metal-metal oxide-graphene triplejunctionsforelectrocatalysisapplications.We firstsynthesizeindiumtin oxide (ITO)nanocrystals directlyon functionalizedgraphene sheets, forming an ITO-graphene hybrid. Platinum nanoparticles are then deposited, form- ing a unique triple-junction structure (Pt-ITO-graphene). Our experimental work and periodic density functional theory (DFT) calculationsshowthatthesupportedPtnanoparticlesaremorestableatthePt-ITO-graphenetriplejunctions.Furthermore,DFT calculations suggest thatthe defects andfunctional groupsongraphene alsoplayan importantroleinstabilizingthe catalysts. These new catalyst materials were tested for oxygen reduction for potential applications in polymer electrolyte membrane fuel cells, and they exhibited greatly enhanced stability and activity.

/pdf/stabilization-of-electrocatalytic-metal-nanoparticles-at-20los3ep4k.pdf

Stabilization of Electrocatalytic Metal Nanoparticles at Metal−Metal Oxide−Graphene Triple Junction Points

The supramolecular assembly of surfactant molecules at a solid–liquid interface can produce tubular structures with diameters of around 10 nm (refs 1,2,3,4), which can be used for the templated polymerization of mesoporous silica thin films3,4,5. The orientation of the tubules depends primarily on the nature of the substrate–surfactant interaction. These nanostructured films hold much promise for applications such as their use as orientated nanowires6, sensor/actuator arrays7,8,9 and optoelectronic devices10. But a method of patterning the tubules and orientating them into designed arrangements is required for many of these possibilities to be realized. Here we describe a method that allows the direction of growth of these tubules to be guided by infiltrating a reaction fluid into the microcapillaries of a mould in contact with a substrate11. An electric field applied tangentially to the surface within the capillaries induces electro-osmotic flow, and also enhances the rates of silica polymerization around the tubules by localized Joule heating. After removal of the mould, patterned bundles of orientated nanotubules remain on the surface. This method permits the formation of orientated mesoporous channels on a non-conducting substrate with an arbitrary microscopic pattern.

/pdf/microscopic-patterning-of-orientated-mesoscopic-silica-14t6im1jz0.pdf

Microscopic patterning of orientated mesoscopic silica through guided growth

/pdf/graphene-materials-and-their-use-in-dye-sensitized-solar-20voypijt2.pdf

Graphene Materials and Their Use in Dye-Sensitized Solar Cells

The single-stranded DNA constrained on graphene surface is effectively protected from enzymatic cleavage by DNase I. The anisotropy, fluorescence, NMR, and CD studies suggest that the single-stranded DNA is promptly adsorbed onto graphene forming strong molecular interactions. Furthermore, the constraint of DNA probe on graphene improves the specificity of its response to complementary DNA. These findings will promote the further application of graphene in biotechnology and biomedical fields.

Ilhan A. Aksay

Papers

Structural Design of Cathodes for Li-S Batteries

Stabilization of Electrocatalytic Metal Nanoparticles at Metal−Metal Oxide−Graphene Triple Junction Points

Microscopic patterning of orientated mesoscopic silica through guided growth

Graphene Materials and Their Use in Dye-Sensitized Solar Cells

Constraint of DNA on Functionalized Graphene Improves its Biostability and Specificity