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

Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal–oxide–semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success...

/pdf/high-k-gate-dielectrics-current-status-and-materials-zjvba0c4u8.pdf

High-κ gate dielectrics: Current status and materials properties considerations

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Coinage metals, such as Au, Ag, and Cu, have been important materials throughout history.1 While in ancient cultures they were admired primarily for their ability to reflect light, their applications have become far more sophisticated with our increased understanding and control of the atomic world. Today, these metals are widely used in electronics, catalysis, and as structural materials, but when they are fashioned into structures with nanometer-sized dimensions, they also become enablers for a completely different set of applications that involve light. These new applications go far beyond merely reflecting light, and have renewed our interest in maneuvering the interactions between metals and light in a field known as plasmonics.2–6

In plasmonics, the metal nanostructures can serve as antennas to convert light into localized electric fields (E-fields) or as waveguides to route light to desired locations with nanometer precision. These applications are made possible through a strong interaction between incident light and free electrons in the nanostructures. With a tight control over the nanostructures in terms of size and shape, light can be effectively manipulated and controlled with unprecedented accuracy.3,7 While many new technologies stand to be realized from plasmonics, with notable examples including superlenses,8 invisible cloaks,9 and quantum computing,10,11 conventional technologies like microprocessors and photovoltaic devices could also be made significantly faster and more efficient with the integration of plasmonic nanostructures.12–15 Of the metals, Ag has probably played the most important role in the development of plasmonics, and its unique properties make it well-suited for most of the next-generation plasmonic technologies.16–18

1.1. What is Plasmonics?
Plasmonics is related to the localization, guiding, and manipulation of electromagnetic waves beyond the diffraction limit and down to the nanometer length scale.4,6 The key component of plasmonics is a metal, because it supports surface plasmon polariton modes (indicated as surface plasmons or SPs throughout this review), which are electromagnetic waves coupled to the collective oscillations of free electrons in the metal.

While there are a rich variety of plasmonic metal nanostructures, they can be differentiated based on the plasmonic modes they support: localized surface plasmons (LSPs) or propagating surface plasmons (PSPs).5,19 In LSPs, the time-varying electric field associated with the light (Eo) exerts a force on the gas of negatively charged electrons in the conduction band of the metal and drives them to oscillate collectively. At a certain excitation frequency (w), this oscillation will be in resonance with the incident light, resulting in a strong oscillation of the surface electrons, commonly known as a localized surface plasmon resonance (LSPR) mode.20 This phenomenon is illustrated in Figure 1A. Structures that support LSPRs experience a uniform Eo when excited by light as their dimensions are much smaller than the wavelength of the light.



Figure 1

Schematic illustration of the two types of plasmonic nanostructures discussed in this article as excited by the electric field (Eo) of incident light with wavevector (k). In (A) the nanostructure is smaller than the wavelength of light and the free electrons ...



In contrast, PSPs are supported by structures that have at least one dimension that approaches the excitation wavelength, as shown in Figure 1B.4 In this case, the Eo is not uniform across the structure and other effects must be considered. In such a structure, like a nanowire for example, SPs propagate back and forth between the ends of the structure. This can be described as a Fabry-Perot resonator with resonance condition l=nλsp, where l is the length of the nanowire, n is an integer, and λsp is the wavelength of the PSP mode.21,22 Reflection from the ends of the structure must also be considered, which can change the phase and resonant length. Propagation lengths can be in the tens of micrometers (for nanowires) and the PSP waves can be manipulated by controlling the geometrical parameters of the structure.23

/pdf/controlling-the-synthesis-and-assembly-of-silver-1ktlgomyt6.pdf

Controlling the synthesis and assembly of silver nanostructures for plasmonic applications

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

/pdf/present-and-future-of-surface-enhanced-raman-scattering-34aqgcm385.pdf

Present and Future of Surface-Enhanced Raman Scattering

This paper investigates the properties of room temperature adsorption of O3 on ultra-thin ALD SnO2. Adsorption is characterized by gravimetric measurements on QCM and frequency shift is converted to mass calculations. Both Langmuir and Freundlich isotherm parameters are calculated for O3 on Au, as-deposited SnO2, and annealed SnO2. Of the samples, annealed SnO2 shows the greatest mass shift and calculated number of adsorption sites. The surface resistivity is estimated to transduce the adsorbed quantity into conductometric respsonse; $\mathrm {\Delta }{R}_{s}=4.037e5\,\,\mathrm {\Omega /sq}$ for an O3 saturated as-deposited ALD SnO2 surface and $\mathrm {\Delta }{R}_{s}=4.859e3\,\,\mathrm {\Omega /sq}$ for the annealed ALD SnO2.

Investigation of O 3 Adsorption on Ultra-Thin ALD SnO 2 by QCM

A novel double floating-gate unified memory device is experimentally demonstrated for the first time. The device can be used to store both volatile and nonvolatile memory states simultaneously. Simulations of scaled devices show that the device offers several advantages compared to conventional memory devices. Such a device could have a dramatic impact on next generation memory architectures.

A novel double floating-gate unified memory device

This paper describes methodologies for fabricating of highly efficient plasmonics-active SERS substrates - having
metallic nanowire structures with pointed geometries and sub-5 nm gap between the metallic nanowires enabling
concentration of high EM fields in these regions - on a wafer-scale by a reproducible process that is compatible with
large-scale development of these substrates. Excitation of surface plasmons in these nanowire structures leads to
substantial enhancement in the Raman scattering signal obtained from molecules lying in the vicinity of the
nanostructure surface. The methodologies employed included metallic coating of silicon nanowires fabricated by
employing deep UV lithography as well as controlled growth of silicon germanium on silicon nanostructures to form
diamond-shaped nanowire structures followed by metallic coating. These SERS substrates were employed for detecting
chemical and biological molecules of interest. In order to characterize the SERS substrates developed in this work, we
obtained SERS signals from molecules such as p-mercaptobenzoic acid (pMBA) and cresyl fast violet (CFV) attached
to or adsorbed on the metal-coated SERS substrates. It was observed that both gold-coated triangular shaped nanowire
substrates as well as gold-coated diamond shaped nanowire substrates provided very high SERS signals for the
nanowires having sub-15 nm gaps and that the SERS signal depends on the closest spacing between the metal-coated
silicon and silicon germanium nanowires. SERS substrates developed by the different processes were also employed for
detection of biological molecules such as DPA (Dipicolinic Acid), an excellent marker for spores of bacteria such as
Anthrax.

Fabrication of novel plasmonics-active substrates

We have successfully designed and fabricated the high current AlGaN/GaN HFET using 4 masks process. We have achieved the maximum on-current of 7.3A at 1.5V with TO-3 power package. Multi-finger cell-design was implemented to achieve high current extraction from specific active area. In addition, the mesa-free design was adopted to reduce the process steps by employing the self-isolation with surrounded Schottky gate. Length of unit finger is 1000um. Total width of multi-finger is 80 mm. The measured Ronsp and breakdown voltage are 3.4mΩ-cm2 and 450V, respectively. Although the designed breakdown voltage (BV) was 600V, BV reduction has been observed after fabrication due to the process variation. However, overall figure of merit of this device is 2 times superior to that of Super Junction Power MOSFET.

Veena Misra

Papers

Investigation of O 3 Adsorption on Ultra-Thin ALD SnO 2 by QCM

A novel double floating-gate unified memory device

Fabrication of novel plasmonics-active substrates

Design and fabrication of high current AlGaN/GaN HFET for Gen III solid state transformer

Investigation of VT Shift Mechanism of High-K Dielectrics caused by Lanthanum Capping for NMOS and Tantalum Capping for PMOS Devices