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

This paper presents reaction sequencing studies conducted for two precursors to the 123 superconductor in air and helium environments. In air, the reactants in both precursor systems produce an intermediate 123 phase at 1000 K without going through the BaCuO{sub 2} and Y{sub 2}BaCuO{sub 5} intermediate phases, observed in earlier work with mixed powder precursors. In helium, the fully developed 123 tetragonal phase is formed at temperatures as low as 880 K, but it also decomposes to Y{sub 2}BaCuO{sub 5}, BaCu{sub 2}O{sub 2}, and BaCuO{sub 2}; the extent of decomposition depends on the temperature. The 123 tetragonal phase completely decomposes by 1075 K, but it can be reformed if the atmosphere is switched back to air at a temperature above 950 K.

Reaction Sequencing During Processing of the 123 Superconductor

Effects of local oxygen ordering on superconducting properties of YBa2Cu3O7−x

Nanocomposite processing via infiltration of mesoporous silica

Structural control with ultrafine particles

Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544 Some biological materials exhibit structural robustness, despite the brittle nature of their constituents.Nacre (mother-of-pearl), the pearly internal layer of many mollusc shells, is addressed in this study. This material comprises about 95% aragonite tablets (a mineral form of CaC03), The polygonal tablets were glued with only a few percent of biological macromolecules into layered structure. The goal of the present study is to elucidate the basic inelastic deformation mechanisms. Typical stress /strain curves in tension and compression are plotted in Fig. 1. All tensile curves exhibited extensive inelastic deformation. After testing, the samples were initially examined using a stereo microscope (Leica MZ8) and a metallurgical microscope (Leica MEF4M) followed by analysis of the structural details using scanning electron microscopy (Philip XL-30). Optical imaging provided a visualization of the inelastic zone, manifest as white tension lines.

Ilhan A. Aksay

Papers

Reaction Sequencing During Processing of the 123 Superconductor

Effects of local oxygen ordering on superconducting properties of YBa2Cu3O7−x

Nanocomposite processing via infiltration of mesoporous silica

Structural control with ultrafine particles

Scanning Electron Microscopic Analysis on the Deformation Mechanisms in NACRE