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

The need for low cost, high speed telecommunication sources demands the maturation of long wavelength vertical cavity lasers (VCLs). Both long haul fiber optic systems and gigabit ethernet links are potential markets for 1.3 and 1.55 micron VCLs. This past year has seen much progress to this end, but the emerging technology has yet to be determined. This paper overviews critical issues in long wavelength VCL design, and discusses the most recent technological advances in the field.

Long wavelength vertical cavity lasers

III-nitride microdisks with InGaN multiple quantum well active regions were fabricated using photoelectrochemical etching. The microdisks were thin, mushroom-shaped devices with smooth undercut surfaces. High quality optical modes were observed. A focused ion beam was used to further polish the microdisk sidewalls, as well as to study the effect of ion damage to the gain region of the microdisk. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Observation of high Q resonant modes in optically pumped GaN/InGaN microdisks fabricated using photoelectrochemical etching

The role of a low-temperature-grown GaAs (LT GaAs) layer on the lateral oxidation of an Al0.98Ga0.02As/GaAs layer structure has been studied by transmission electron microscopy. Results show that structures incorporating LT GaAs develop better quality oxide/GaAs interfaces compared to reference samples without LT GaAs. While the latter have As accumulation in the vicinity of these interfaces, the structures with LT layers display sharper oxide–GaAs interfaces with a reduced concentration of As. These results are explained in terms of the high Ga vacancy concentration in the LT GaAs and the possible influence of those vacancies in enhancing As diffusion away from the oxide–semiconductor interface.

Improvement of the interface quality during thermal oxidation of Al0.98Ga0.02As layers due to the presence of low-temperature-grown GaAs

The authors describe a Fabry-Perot technique for determining the reflectivity and the phase of the interface between semiconductor and a multilayer metal structure as it will be realised in actual device fabrication. The reflection coefficients of GaAs to Ti/Au, Pd/Au, Au and Ag interfaces are measured at 1.55 /spl mu/m.

Characterisation of metal mirrors on GaAs

High quality YBa2Cu3O7−x films have been grown on MgO epitaxial buffer layers deposited onto a GaAs/AlGaAs heterostructure incorporating a two‐dimensional electron gas (2DEG). The critical temperature of the YBa2Cu3O7−x, Tc(0) was ≳80 K, and Jc≳2×104 A/cm2 at 77 K. Electron mobilities and concentrations of 2DEG substrates were measured at different stages in the formation of YBa2Cu3O7−x/MgO/2DEG structure. Room‐temperature mobilities and concentrations were unchanged after YBa2Cu3O7−x/MgO deposition, while low‐temperature mobilities were slightly degraded. It is found that the degradation of electron mobility is correlated to the high growth temperature of YBa2Cu3O7−x. Since the 2DEG is only 1200 A from the substrate surface, this constitutes a sensitive demonstration of the viability of the semiconductor substrate under these growth conditions.

Evelyn L. Hu

Papers

Long wavelength vertical cavity lasers

Observation of high Q resonant modes in optically pumped GaN/InGaN microdisks fabricated using photoelectrochemical etching

Improvement of the interface quality during thermal oxidation of Al0.98Ga0.02As layers due to the presence of low-temperature-grown GaAs

Characterisation of metal mirrors on GaAs

Temperature‐dependent mobility of a GaAs/AlGaAs heterostructure after deposition of MgO and superconducting YBa2Cu3O7−x