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

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

Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications

物件導向軟體之架構(Object-Oriented Software Construction)探討

Author(s): Vogel, Alfred; Venugopalan, Vasan | Abstract: The mechanisms of pulsed laser ablation of biological tissues were studied. The transiently empty space created between the fiber tip and the tissue surface improved the optical transmission to the target and thus increased the ablation efficiency. It was found that the structure and morphology also affect the energy transport among tissue constituents.

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Mechanisms of pulsed laser ablation of biological tissues.

The luminescence of silver bromide crystals doped with rare earth ions (Nd 3+ ) was investigated in the visible and near infrared spectral ranges The emission, excitation, and absorption spectra, as well as the kinetic parameters, were measured over a broad temperature range Crysta! doping was produced by growing in the melt and by a diffusion method A novel mcthod for measuring the diffusion profile of rare earth ions in AgBr crystals, based on the luminescence distribution of the dopant, was proposed The luminescence parameters of AgBr:Nd crystals doped by the diffusion method were compared with these for crystals doped by adding Nd 3+ to the melt The spectroscopy parameters of Pr 3+ and Er 3+ ions in AgBr crystals doped in the melt were also investigated The Judd-Ofelt analysis was applied to the rare-earth doped crystals, and transition rates, branching ratios, and quantum efficiencies were calculated Good agreement between theory and experiment was obtained

Silver halide lasers and amplifiers: Nd ion diffusion in AgBr crystals

Polycrystalline silver halide AgClBr fibers are highly transparent in the mid-IR. They are flexible, insoluble in water non-toxic and biocompatible. These fibers are potentially useful for many applications, such as laser surgery, fiberoptic thermometry and infrared spectroscopy. Typical core/clad fibers consist of Br rich core and Cl rich cladding, and they normally have relatively large cores (diameters larger than 350μm) and low transmission losses. There is a wide interest in the development of core/clad fibers with core diameters smaller than 200μm, yet with low transmission losses. Such small core fibers would be useful for all the applications mentioned above. We have developed core/clad fibers with core diameters 140μm and with transmission losses of about 1dB/m at a wavelength of 10.6 microns. The properties of the fibers and some of their applications will be discussed.

Silver halide infrared transmitting core/clad fibers with small cores

Grating coupled emission Pb1−xSnxSe/Pb1−x−yEuySnxSe double‐heterostructure stripe‐geometry diode lasers were fabricated using molecular beam epitaxy. Low‐divergence far‐field patterns of ∼5° for multimode operation and ∼2° for single‐mode operation were obtained. These are the lowest values ever achieved with Pb salt lasers.

Highly collimated laser beams from grating coupled emission Pb1−xSnxSe/Pb1−x−yEuySnxSe diode lasers

Silver halide infrared transmitting optical fibers are used in a noncontact mode to deliver and collect infrared radiation from a thin liquid sample on a highly reflecting substrate. The detected signal is a sensitive measure of the absorption spectrum of the liquid under study. Optimal placement of the fibers with respect to the sample was calculated and experimentally confirmed. The system provides a quantitative infrared spectrum with minimal sample preparation.

Noncontact infrared reflection spectroscopy using optical fibers

This work p resents the novel composite material based on a polymer (LDPE) and metal alloy, which h ave a close melting point. The process of blending the main components of the composite was developed using the extrusion mixing. The process of extrusion of thin (50-250 m) films based on the c omposite was worked o ut using an extruder equipped with a cast film die. This process allowed production of the binary composite, with up to 15 wt.% of the alloy dispersed u niformly in the polymer matrix. It was s hown that carbon black is highly compatible with the basic components and could be dispersed uniformly in the obtained films. The structure of the c omposite films was s tudied with a scanning electron microscope. Physical properties of the binary and ternary composites were investigated, including conductivity and temperature dependence of the thermal capacity. Non-ohmic behavior of the ternary composites was revealed. The IR spectra of the c omposites were studied using an FTIR spectrophotometer. It was shown that processing polyethylene in the presence of a low-melting-point alloy causes changes in the structure of polyethylene. The presence of alloy caused intensive oxidation of carbon black in the ternary composite as well.

Abraham Katzir

Papers

Silver halide lasers and amplifiers: Nd ion diffusion in AgBr crystals

Silver halide infrared transmitting core/clad fibers with small cores

Highly collimated laser beams from grating coupled emission Pb1−xSnxSe/Pb1−x−yEuySnxSe diode lasers

Noncontact infrared reflection spectroscopy using optical fibers

Development of a novel composite based on polyethylene and low-melting-point metal alloy