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

The nacreous (mother-of-pearl) sections of molluscan shells are natural laminates of aragonitic calcium carbonate platelets and an organic matrix. The multi-edged platelets are sub-micrometer thick and surrounded on all sides by 10–20 nm-thick organic matrix that contains several proteins and polysaccharides. Our goal is to identify the components and structure of the organic matrix and determine their function in shell formation and organization. We have extracted organic material from red abalone-Haliotis rufescens, and chambered nautilus-Nautilus pompilius. From the soluble portion, we have partially purified two proteins and determined their amino acid compositions.

/pdf/preliminary-characterization-of-organic-nucleator-and-15xk6d5knh.pdf

Preliminary Characterization of Organic Nucleator and Framework Macromolecules in Mollusc Shells

Surfactant mediated deformation of gold particles

Nickel impurities in the 90K superconductor

: Biomimicking is now regarded as an area of research in which the analysis of natural materials will provide insights into the design of novel manmade materials, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex composites possessing unique properties with greater control than is possible with synthetic materials. Biological materials often have hierarchical structures with unprecedented properties at spatial levels on the molecular, micrometer, and macrometer seals. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old or damaged components. With this in mind, this workshop is intended to identify the most critical issues and to establish future directions for biomimicking in materials science and engineering. The goals of this workshop are to further educate the Air Force participants in the possibilities of biomimetric design and processing and to encourage the research participants to address the interfacing of these possibilities with aerospace needs. Natural materials cannot be used for many aerospace applications because of their chemical instability at the temperatures associated with their use.

Workshop on the Design and Processing of Materials by Biomimicking Held in Seattle, Washington on 2-4 April 1991

The length scales defining structure and organization determine the fundamental characteristics of a material. Traditional ceramic materials exhibit organization on two length scales: the atomic scale, e.g., the unit cell of the crystal or the local arrangement of amorphous materials, and the scale of the grain size within the composite, typically much longer length and on the order of micrometers or greater. In biogenic materials, however, we observe a much broader range of organizational length scales: (1) a hierarchical organization always starts at the nanometer length scale, in which case, nanostructural design is the building block of larger scale composite structures; and (2) the nested levels of structural hierarchy appear to yield improved properties for particular functions (Aksay et al. 1994; NAP 1994).

/pdf/nanostructured-ceramics-through-self-assembly-3fjip64wvl.pdf

Ilhan A. Aksay

Papers

Preliminary Characterization of Organic Nucleator and Framework Macromolecules in Mollusc Shells

Surfactant mediated deformation of gold particles

Nickel impurities in the 90K superconductor

Workshop on the Design and Processing of Materials by Biomimicking Held in Seattle, Washington on 2-4 April 1991

Nanostructured ceramics through self-assembly