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

The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

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Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Recent developments have greatly improved the sensitivity of optical sensors based on metal nanoparticle arrays and single nanoparticles. We introduce the localized surface plasmon resonance (LSPR) sensor and describe how its exquisite sensitivity to size, shape and environment can be harnessed to detect molecular binding events and changes in molecular conformation. We then describe recent progress in three areas representing the most significant challenges: pushing sensitivity towards the single-molecule detection limit, combining LSPR with complementary molecular identification techniques such as surface-enhanced Raman spectroscopy, and practical development of sensors and instrumentation for routine use and high-throughput detection. This review highlights several exceptionally promising research directions and discusses how diverse applications of plasmonic nanoparticles can be integrated in the near future.

Biosensing with plasmonic nanosensors

The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon resonance of a nanostructured surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon to a rapidly developing analytical tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithography for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere surfaces as excellent candidates for several experiments that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chemical warfare agents and several biological molecules.

Surface-Enhanced Raman Spectroscopy

We introduce a new technique for rapidly heating (106 °C/s) thin films using an electrical thermal annealing (ETA) pulse technique. By applying a high‐current dc electrical pulse to a conductive substrate‐heater material (Si), joule heating occurs thus heating the thin film. This method was demonstrated by heating thin films of aluminum at rates ranging from 103 to 106 °C/s. The temperature of the system is measured by using the substrate heater as a thermistor and is found to be within ≊±10 °C during anneals at ≊105 °C/s. Phase transformations in the Ti‐Si system were also observed using in situ resistivity measurements during ETA at ≊104 °C.

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1 000 000 °C/s thin film electrical heater: In situ resistivity measurements of Al and Ti/Si thin films during ultra rapid thermal annealing

We have developed a new thin-film differential scanning calorimetry technique that has extremely high sensitivity of 0.2 nJ. By combining two calorimeters in a differential measurement configuration, we have measured the heat capacity and melting process of Sn nanostructures formed via thermal evaporation with deposition thickness down to 1 A. The equivalent resolution of the calorimeter is 1 nanogram in mass or 0.4 A in thickness. We have observed a decrease of up to 120°C in the melting point of Sn nanostructures.

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Heat capacity measurements of Sn nanostructures using a thin-film differential scanning calorimeter with 0.2 nJ sensitivity

We introduce a scanning calorimeter for use with a single solid or liquid sample with a volume down to a few nanoliters. Its use is demonstrated with the melting of 52 nL of indium, using heating rates from 100 to 1000 K/s. The heat of fusion was measured to within 5% of the bulk value, and the sensitivity of the measurement was ±7 μW. The heat of vaporization of water was measured in the scanning mode to be within ±23% of the bulk value by actively vaporizing water droplets from 2 to 100 nL in volume. Results within 25% were obtained for the heat of vaporization by using the calorimeter in a heat-conductive mode and measuring the passive evaporation of water. Temperature measurements over a period of 10 h had a standard deviation of 3 mK.

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Scanning calorimeter for nanoliter-scale liquid samples

Glass transition in ultrathin polymer films is the subject of intense interest due to theoretical and experimental issues regarding size-dependent effects in finite systems.1,2 The small sample size presents unique challenges to experimentalists, and subsequently a variety of techniques have been utilized1-5 with varying results. The standard technique for glass transition studies6,7 is differential scanning calorimetry (DSC), which is of special interest in this field because it yields absolute thermodynamic properties such as heat capacity. However, it is difficult to use conventional DSC systems on ultrathin samples because of the insufficient sensitivity. In this paper we demonstrate a recently developed MEMS-based thin-film differential scanning calorimetry (TDSC) device (also referred to as nanocalorimetry) which shows potential for studies of glass transition for films with nanometer-range thickness. In our previous work in polyethylene8 and metals9-11 we have measured the heat capacity, heat of fusion, and melting temperature for discontinued films with average thickness of less than 1 nm. TheTDSCtechniqueisdescribedindetailelsewhere.8-11 In brief, TDSC uses a microfabricated sensor shown in Figure 1 as a calorimetric cell. The sensor consists of a Si3Nx membrane supported at the perimeter by a Si substrate. A 500 μm wide metal strip is deposited on the membrane and functions both as a heater and as a thermometer/RTD. Platinum is used as a material of choice for the metal strip due to its enhanced time stability of electrical resistance. The Pt heater/thermometer, the Si3Nx membrane directly beneath it, and a sample film deposited on either the Pt or Si3Nx surface form a sample calorimetric cell. The extremely low thickness of the Pt strip (50 nm) and Si3Nx membrane (30 nm) provides a mass addenda, which is small enough to measure the heat capacity (Cp) of nanometerthick films. The high-sensitivity differential mode is achieved by using the second reference sensor which is identical to the polymer-coated sample sensor but has no material on it.11 Before the experiment, the resistance of both sensors is calibrated against the temperature in a three-zone tube vacuum furnace. The measurement is initiated by supplying a short pulse of electric current to the Pt strip. This rapidly increases the temperature of the cell by Joule heating. The vacuum environment (10-7-10-8 Torr) and high * Corresponding author. E-mail: L-ALLEN9@uiuc.edu. Figure 1. MEMS-based calorimetric sensor for TDSC (not to scale). Volume 35, Number 5 February 26, 2002

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Thin-film differential scanning calorimetry: A new probe for assignment of the glass transition of ultrathin polymer films

Microstructural study of the C49–TiSi2 to C54–TiSi2 polymorphic transformation has been performed to elucidate microstructural evolution and possible mechanism of the phase transformation. It has been shown that the nucleation of the C54–TiSi2 is heterogeneous, and preferentially takes place at triple grain junctions or grain boundaries. The interphase interfaces between C49 and C54 disilicides are often ragged with incoherent characteristics. The growth of the C54 phase is found to proceed by advancing the highly mobile incoherent interfaces in all directions toward the heavily faulted C49 phase. No rigorous orientation relationships are found between the two phases. The microstructural features of the transformation bear some massive characteristics.

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Leslie H. Allen

Papers

1 000 000 °C/s thin film electrical heater: In situ resistivity measurements of Al and Ti/Si thin films during ultra rapid thermal annealing

Heat capacity measurements of Sn nanostructures using a thin-film differential scanning calorimeter with 0.2 nJ sensitivity

Scanning calorimeter for nanoliter-scale liquid samples

Thin-film differential scanning calorimetry: A new probe for assignment of the glass transition of ultrathin polymer films

Microstructural aspects and mechanism of the C49‐to‐C54 polymorphic transformation in titanium disilicide