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

Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.

Semiconductor Clusters, Nanocrystals, and Quantum Dots

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

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

Highly luminescent semiconductor quantum dots (zinc sulfide-capped cadmium selenide) have been covalently coupled to biomolecules for use in ultrasensitive biological detection. In comparison with organic dyes such as rhodamine, this class of luminescent labels is 20 times as bright, 100 times as stable against photobleaching, and one-third as wide in spectral linewidth. These nanometer-sized conjugates are water-soluble and biocompatible. Quantum dots that were labeled with the protein transferrin underwent receptor-mediated endocytosis in cultured HeLa cells, and those dots that were labeled with immunomolecules recognized specific antibodies or antigens.

http://science.sciencemag.org/content/sci/281/5385/2016.full.pdf

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

: The extinguishing characteristics of a Cs-Ba tacitron as a switch/inverter are investigated experimentally in three modes of operation: breakdown mode, I-V mode, and current modulation mode Operation parameters measured include switching frequency up to 8 kHz, hold off voltage up to 180 V, current densities in excess of 15 A/cm2, switch power density of 1 kW/cm2, voltage drop as low as 15 volts, for a switching efficiency in excess of 94% at collector voltages greater than 30 V The voltage drop during both the I-V and current modulation modes strongly depend on the Cs pressure and to a lesser extent on the emission properties of the emitter (ie emitter temperature and Ba pressure) Increasing the Cs pressure and/or the emission current decreases the voltage drop in the triode sections However, for the same initial Cs pressure and emission conditions, the voltage drop in the I-V mode is usually lower than that during current modulation Results show that at an initial Cs pressure of 20 mtorr, Ba pressure of 01 mtorr, and emitter temperature of 1400 C, the voltage drop in the triode section in the I-V mode could be as low as 15 V At the same operation condition during stable current modulation, so long as the discharge current is kept lower that the emission current, the voltage drop could be as low as 3 V The Cs pressure, Ba pressure and emitter temperature influence not only the voltage drop but also the stable current modulation of the device (ie ignition and extinguishing of the discharge occur when positive and negative pulses are applied to the grid, respectively) Results show that in order for stable modulation to occur the initial amount of Cs atoms in the discharge volume at the time of ignition should be sufficiently high, however, in order to successfully extinguish the device, the heavy components in the discharge volume should be sufficien

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA338912&Location=U2&doc=GetTRDoc.pdf

Cs-Ba Tacitron: I. Extinguishing Characteristics

Herstellungsverfahren für Übergangsmetall-Nanopartikeln

Self-assembled Supraparticles by Spherical Confinement

For decades, the spontaneous organization of nanocrystals into superlattices has captivated the scientific community. However, achieving direct control over the formation of the superlattice and its phase transformations has proven to be a grand challenge, often resulting in the generation of multiple symmetries under the same experimental conditions. Here, we achieve direct control over the formation of the superlattice and its phase transformations by modulating the thermal energy of a nanocrystal dispersion without relying on solvent evaporation. We follow the temperature-dependent dynamics of the self-assembly process using synchrotron-based small-angle X-ray scattering. When cooled below -24.5 °C, lead sulfide nanocrystals form micrometer-sized three-dimensional phase-pure body-centered cubic superlattices. When cooled below -35.1 °C, these superlattices undergo a collective diffusionless phase transformation that yields denser body-centered tetragonal phases. These structural changes can be reversed by increasing the temperature of the dispersion and may lead to the direct modulation of the optical properties of these artificial solids.

Temperature-Controlled Reversible Formation and Phase Transformation of 3D Nanocrystal Superlattices Through In Situ Small-Angle X-ray Scattering.

Initially, vanadium dioxide seems to be an ideal first-order phase transition case study due to its deceptively simple structure and composition, but upon closer inspection there are nuances to the driving mechanism of the metal-insulator transition (MIT) that are still unexplained. In this study, a local structure analysis across a bulk powder tungsten-substitution series is utilized to tease out the nuances of this first-order phase transition. A comparison of the average structure to the local structure using synchrotron x-ray diffraction and total scattering pair-distribution function methods, respectively, is discussed as well as comparison to bright field transmission electron microscopy imaging through a similar temperature-series as the local structure characterization. Extended x-ray absorption fine structure fitting of thin film data across the substitution-series is also presented and compared to bulk. Machine learning technique, non-negative matrix factorization, is applied to analyze the total scattering data. The bulk MIT is probed through magnetic susceptibility as well as differential scanning calorimetry. The findings indicate the local transition temperature ([Formula: see text]) is less than the average [Formula: see text] supporting the Peierls-Mott MIT mechanism, and demonstrate that in bulk powder and thin-films, increasing tungsten-substitution instigates local V-oxidation through the phase pathway VO[Formula: see text] V[Formula: see text]O[Formula: see text] V[Formula: see text]O[Formula: see text]. 

/pdf/local-structure-elucidation-of-tungsten-substituted-vanadium-3fthbpcs.pdf

Christopher B. Murray

Papers

Cs-Ba Tacitron: I. Extinguishing Characteristics

Herstellungsverfahren für Übergangsmetall-Nanopartikeln

Self-assembled Supraparticles by Spherical Confinement

Temperature-Controlled Reversible Formation and Phase Transformation of 3D Nanocrystal Superlattices Through In Situ Small-Angle X-ray Scattering.

Local structure elucidation of tungsten-substituted vanadium dioxide (V[Formula: see text]W[Formula: see text]O[Formula: see text]).