Younan Xia

Bio: Younan Xia is an academic researcher from The Wallace H. Coulter Department of Biomedical Engineering. The author has contributed to research in topics: Nanocages & Nanowire. The author has an hindex of 216, co-authored 943 publications receiving 175757 citations. Previous affiliations of Younan Xia include Washington University in St. Louis & University of Texas at Dallas.

Synthesis of Rhodium Concave Tetrahedrons by Collectively Manipulating the Reduction Kinetics, Facet-Selective Capping, and Surface Diffusion

Abstract: This paper describes a facile synthesis of Rh tetrahedrons with concave side faces by collectively manipulating the reaction kinetics, facet-selective capping, and surface diffusion of atoms. Specifically, a combination of Na3RhCl6, triethylene glycol, l-ascorbic acid, and citric acid provides the right conditions for generating the concave tetrahedrons. After the formation of small Rh tetrahedral seeds through self-nucleation, the subsequently generated Rh atoms were selectively deposited onto the corner sites to generate Rh tetrapods. At the same time, the deposited atoms could diffuse from the corners to edges to generate concave side faces because the diffusion to face sites was restrained by the citric acid adsorbed on the {111} facets. This study offers deep insight into the growth mechanism involved the formation of noble-metal nanocrystals with concave surfaces. The Rh concave tetrahedrons were encased by a mix of {111} and {110} facets, showing great potential for catalytic applications.

Method of forming articles and patterning surfaces via capillary micromolding

Abstract: Techniques for patterning chemically or biochemically active agents on a substrate surface involve providing a micromold having a contoured surface including indentations defining a pattern and forming, on a substrate surface, a chemically or biochemically active agent or fluid precursor of a structure on the surface. A chemically or biochemically active agent or fluid precursor also can be transferred from indentations in an applicator to a substrate surface. The substrate surface can be planar or non-planar. Fluid precursors of polymeric structures, inorganic ceramics and salts, and the like can be employed to form patterned polymeric articles, inorganic salts and ceramics, etc. at the surface. The articles, according to one aspect, are formed in a pattern including a portion having a lateral dimension of less than about 1 millimeter. Smaller dimensions can be achieved. The indentation pattern of the applicator can be used to transfer separate, distinct chemically or biochemically active agents or fluid precursors to separate, isolated regions of a substrate surface. The invention provides for inexpensive and simple synthesis of a combinatorial chemical or biochemical library.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

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

Abstract: 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。

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346