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

This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge-based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin-polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin-based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.

http://science.sciencemag.org/content/sci/294/5546/1488.full.pdf

Spintronics: a spin-based electronics vision for the future.

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

/pdf/spintronics-fundamentals-and-applications-2dx38n6phu.pdf

Spintronics: Fundamentals and applications

We report a method to form multifunctional polymer coatings through simple dip-coating of objects in an aqueous solution of dopamine. Inspired by the composition of adhesive proteins in mussels, we used dopamine self-polymerization to form thin, surface-adherent polydopamine films onto a wide range of inorganic and organic materials, including noble metals, oxides, polymers, semiconductors, and ceramics. Secondary reactions can be used to create a variety of ad-layers, including self-assembled monolayers through deposition of long-chain molecular building blocks, metal films by electroless metallization, and bioinert and bioactive surfaces via grafting of macromolecules.

/pdf/mussel-inspired-surface-chemistry-for-multifunctional-1noq7vcby7.pdf

Mussel-Inspired Surface Chemistry for Multifunctional Coatings

Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near-infrared emission during surgery. The new generations of qdots have farreaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.

/pdf/quantum-dots-for-live-cells-in-vivo-imaging-and-diagnostics-3y9ayecoh8.pdf

Quantum Dots for Live Cells, in Vivo Imaging, and Diagnostics

HCl radical beam etching has been used to produce strain‐induced lateral confinement in a GaAs quantum well. This confinement was generated in the GaAs quantum well by radical beam etching a grating pattern into a pseudomorphic, strained layer of In0.35Ga0.65As which overlies the GaAs quantum well. The photoluminescence spectrum showed two peaks, corresponding to the GaAs quantum well both beneath the strained layer and in regions where the strained overlayer had been etched away. The peak due to strain‐induced confinement displayed a redshift that increases with etch time; the maximum shift observed was 20 meV. The after‐etch photoluminescence intensity and the systematic peak shift with etch time are indicators of the degree of control and low‐damage nature of the etch process used.

Systematic observation of strain‐induced lateral quantum confinement in GaAs quantum well wires prepared by chemical dry etching

We have studied the effects of the proximity of a bare Al0.3Ga0.7As surface on the luminescence of an underlying GaAs quantum well (QW) before and after hydrogenation. The mechanism which is affected by H is tunneling to surface states through the surface barrier. Its thickness was varied by wet etching from 60 to 350 A. Our experiments reveal that the degradation of luminescence efficiency from the QW is dependent on the surface barrier thickness and the excitation energy used in the photoluminescence measurements. A complete recovery or even further enhancement of luminescence efficiency was observed in the near‐surface QW after low‐energy ion‐beam hydrogenation, even at room temperature.

Luminescence efficiency of near‐surface quantum wells before and after ion‐gun hydrogenation

The use of color vision as a tool for machine vision provides a powerful means of performing rapid, accurate inspection of microelectronic structures. Since microelectronics fabrication is in large part a thin film technology, and since thin films have characteristic colors, this approach extends the range of optical analysis possible. We have constructed a color vision system used to measure thin film dielectric materials. Color matching is performed rapidly (<100 msecs) and with resolution better than 20 A. The resolution limit has been so far set only by the samples available for measurement. We have further extended the capability of the system beyond simple color matching to identify true unknown samples whose thickness fall within the range of the original system database. Feed-back control of the illumination has been incorporated into the system; we present data on the effect of shifts in lighting or magnification. Microscopic, as well as broad area measurements (for uniformity) can be made.

A color vision system for film thickness determination

We have investigated the influence of concurrent above‐band‐gap laser illumination on the damage profile of GaAs/AlGaAs heterostructures subject to low energy (sub‐keV) Ar+ ion bombardment. A dramatic change in damage profile was observed for these samples, compared with those that were not laser illuminated, and the degradation increases with the illuminated power intensity. Below‐band‐gap illumination results in a minimal increase in damage profile. Such results indicate the possibility of radiation‐enhanced diffusion of defects, and may explain the observed high defect diffusivity at room temperature.

Evelyn L. Hu

Papers

Systematic observation of strain‐induced lateral quantum confinement in GaAs quantum well wires prepared by chemical dry etching

Luminescence efficiency of near‐surface quantum wells before and after ion‐gun hydrogenation

A color vision system for film thickness determination

Radiation enhanced diffusion of low energy ion-induced damage

MOCVD Growth and Properties of InGaN/GaN Multi-Quantum Wells