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

Surface plasmons are waves that propagate along the surface of a conductor. By altering the structure of a metal's surface, the properties of surface plasmons--in particular their interaction with light--can be tailored, which offers the potential for developing new types of photonic device. This could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy and bio-photonics.

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Surface plasmon subwavelength optics

We present experimental scattering data at microwave frequencies on a structured metamaterial that exhibits a frequency band where the effective index of refraction (n) is negative. The material consists of a two-dimensional array of repeated unit cells of copper strips and split ring resonators on interlocking strips of standard circuit board material. By measuring the scattering angle of the transmitted beam through a prism fabricated from this material, we determine the effective n, appropriate to Snell's law. These experiments directly confirm the predictions of Maxwell's equations that n is given by the negative square root of epsilon.mu for the frequencies where both the permittivity (epsilon) and the permeability (mu) are negative. Configurations of geometrical optical designs are now possible that could not be realized by positive index materials.

/pdf/experimental-verification-of-a-negative-index-of-refraction-37hlxn3tta.pdf

Experimental Verification of a Negative Index of Refraction

We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu//sub eff/, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of /spl mu//sub eff/. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly nonlinear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states.

/pdf/magnetism-from-conductors-and-enhanced-nonlinear-phenomena-2fpnoamwae.pdf

Magnetism from conductors and enhanced nonlinear phenomena

The emerging field of plasmonics has yielded methods for guiding and localizing light at the nanoscale, well below the scale of the wavelength of light in free space. Now plasmonics researchers are turning their attention to photovoltaics, where design approaches based on plasmonics can be used to improve absorption in photovoltaic devices, permitting a considerable reduction in the physical thickness of solar photovoltaic absorber layers, and yielding new options for solar-cell design. In this review, we survey recent advances at the intersection of plasmonics and photovoltaics and offer an outlook on the future of solar cells based on these principles.

Plasmonics for improved photovoltaic devices

Time has emerged as a new degree of freedom for metamaterials, promising new pathways in wave control. However, electromagnetism suffers from limitations in the modulation speed of material parameters. Here we argue that these limitations can be circumvented by introducing a traveling-wave refractive index modulation, with the same phase velocity of the waves. We show how the concept of "luminal grating" can yield giant nonreciprocity, achieve efficient one-way amplification, pulse compression and frequency up-conversion, proposing a realistic implementation in double-layer graphene.

/pdf/broadband-nonreciprocal-thz-amplification-in-luminal-1ermrnbbju.pdf

Broadband nonreciprocal THz amplification in luminal graphene metasurfaces

Symmetry and transport in disordered systems

A numerical investigation is presented for the electromagnetic behaviour of Swiss Roll metamaterials that show considerable agreement with analytical theory. Their chiral design exhibits enormous chirality, at least 100 times larger than other chiral structures previously reported in the literature. This property ensures the change of a wave polarization by 90 ∘ in less than a wavelength. Hence, chiral Swiss Rolls support a negative refractive band for one-wave polarization, which is predicted analytically and calculated numerically.

Chirality in Swiss Roll metamaterials

Plasmonic systems have attracted remarkable interest due to their application to the subwavelength confinement of light and the associated enhancement of light-matter interactions. However, this requires light to dwell at a given spatial location over timescales longer than the coupling rate to any relevant loss mechanism. Here we develop a general strategy for the design of stopped-light plasmonic metasurfaces, by taking advantage of the conformal symmetry which underpins near-field optics. By means of the analytical technique of transformation optics, we propose a class of plasmonic gratings which is able to achieve ultra-slow group velocities, effectively freezing surface plasmon polaritons in space over their whole lifetime. Our method can be universally applied to the localization of polaritons in metallic systems, as well as in highly doped semiconductors and even two-dimensional conductive and polar materials, and may find potential applications in nano-focusing, nano-imaging, spectroscopy and light-harvesting.

Plasmon Localization Assisted by Conformal Symmetry

Metamaterials owe their electromagnetic properties to their physical structure rather than to their chemical composition, a characteristic they share with photonic crystals.

John B. Pendry

Papers

Broadband nonreciprocal THz amplification in luminal graphene metasurfaces

Symmetry and transport in disordered systems

Chirality in Swiss Roll metamaterials

Plasmon Localization Assisted by Conformal Symmetry

Metamaterials - An Overview