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

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

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

The unprecedented ability of nanometallic (that is, plasmonic) structures to concentrate light into deep-subwavelength volumes has propelled their use in a vast array of nanophotonics technologies and research endeavours. Plasmonic light concentrators can elegantly interface diffraction-limited dielectric optical components with nanophotonic structures. Passive and active plasmonic devices provide new pathways to generate, guide, modulate and detect light with structures that are similar in size to state-of-the-art electronic devices. With the ability to produce highly confined optical fields, the conventional rules for light-matter interactions need to be re-examined, and researchers are venturing into new regimes of optical physics. In this review we will discuss the basic concepts behind plasmonics-enabled light concentration and manipulation, make an attempt to capture the wide range of activities and excitement in this area, and speculate on possible future directions.

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Plasmonics for extreme light concentration and manipulation.

We have fabricated homogeneous thin films of an alloy of Au and Ag, by annealing two consecutive deposited layers of Au and Ag We have also successfully fabricated nanodisks and nanorods made of AuAg alloys by annealing the nanostructures at 300 °C for 5 hours showing that the nanostructures retain their shape after annealing The developed process additionally enables tailoring the properties of the plasmonic material, providing a supplementary degree of freedom and enables the fabrication of a variety of plasmonic nanostructures with the properties of the request

Fabrication of Alloyed Plasmonic Nanostructures

While multipoles expansions have become ubiquitous in the analysis of plasmonic and dielectric nanostructures and metasurfaces, their zoology remains quite complex. Depending on the physical system, it appears that different multipoles families – including somewhat exotic toroidal multipoles – are required to compute the response of the system. In this work, we present a facile derivation of the three multipoles families: the Cartesian primitive multipoles, the Cartesian irreducible multipoles and the spherical multipoles. We illustrate the links between them and demonstrate their utilization in practical situations to guide experiments. 

Multipoles made simple and universal

We study the angular scattering behavior of bianisotropic metasurfaces and deduce relationships between the corresponding symmetrical angular scattering properties and the structural symmetries of their scattering particles. This may be of practical interest for the realization of metasurfaces with complex angular scattering characteristics.

Symmetries and Angular Scattering Properties of Metasurfaces

It has been observed that achiral nano-particles, such as flat helices, may be subjected to an optical torque even when illuminated by normally incident linearly polarized light. However, the origin of this fascinating phenomenon has so far remained mostly unexplained. We therefore propose an exhaustive discussion that provides a clear and rigorous explanation for the existence of such a torque. Using multipolar theory, and taking into account nonlocal interactions, we find that this torque stems from multipolar pseudochiral responses that generate both spin and orbital angular momenta. We also show that the nature of these peculiar responses makes them particularly dependent on the asymmetry of the particles. By elucidating the origin of this type of torque, this work may prove instrumental for the design of high-performance nano-rotors.

Multipolar Pseudochirality Induced Optical Torque

Reflectivity modulation is a critical feature for applications in telecommunications, 3D imaging and printing, advanced laser machining, or portable displays. Tunable metasurfaces have recently emerged as a promising implementation for miniaturized and high-performance tunable optical components. Commonly, metasurface response tuning is achieved by electro-optical effects. In this work, we demonstrate reflectivity modulation based on a nanostructured, mechanically tunable, metasurface, consisting of an amorphous silicon nanopillar array and a suspended amorphous silicon membrane with integrated electrostatic actuators. With a membrane displacement of only 150 nm, we demonstrate reflectivity modulation by Mie resonance enhanced absorption in the pillar array, leading to a reflectivity contrast ratio of 1:3 over the spectral range from 400–530 nm. With fast, low-power electrostatic actuation and a broadband response in the visible spectrum, this mechanically tunable metasurface reflectivity modulator could enable high frame rate dynamic reflective displays.

https://pubs.acs.org/doi/pdf/10.1021/acsphotonics.3c00276

Olivier J. F. Martin

Papers

Fabrication of Alloyed Plasmonic Nanostructures

Multipoles made simple and universal

Symmetries and Angular Scattering Properties of Metasurfaces

Multipolar Pseudochirality Induced Optical Torque

Broadband Mechanically Tunable Metasurface Reflectivity Modulator in the Visible Spectrum