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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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the polyol method was employed to synthesize copper(I) oxide (Cu2O) nanostructures with well-defined shapes and in large quantities.
Abstract: We have employed the polyol method to synthesize copper(I) oxide (Cu2O) nanostructures with well-defined shapes and in large quantities. Transmission electron microscopy and X-ray powder diffraction studies show that polycrystalline colloidal spheres could be prepared in high yields by simply reducing copper nitrate with ethylene glycol heated to 140 °C in the presence of poly(vinyl pyrrolidone). When a small amount of sodium chloride was introduced, single-crystal nanocubes were obtained. In this case, chloride seems to play a pivotal role in controlling the formation of seeds and the growth rates of various crystallographic planes to shape the Cu2O nanostructures into nanocubes. Based on the structural analysis of samples obtained at different growth times, we also proposed a plausible mechanism to account for the formation of these two distinctive morphologies under different conditions.

141 citations

Journal ArticleDOI
TL;DR: The evolution of CO(2) bubbles led to the formation of small holes in the PLGA shell and thus rapid release of the encapsulated drug doxorubicin.
Abstract: Prepared to self-destruct: when poly(D, L-lactic-co-glycolic acid) (PLGA) hollow microspheres containing NaHCO(3) entered the endocytic organelles of a live cell, the NaHCO(3) in the aqueous core reacted with protons that infiltrated from the compartment to generate CO(2) gas. The evolution of CO(2) bubbles led to the formation of small holes in the PLGA shell and thus rapid release of the encapsulated drug doxorubicin.

140 citations

Journal ArticleDOI
23 Sep 2016-ACS Nano
TL;DR: Based on the results from a set of time-lapse studies and control experiments, a plausible mechanism to account for the formation of Ag nanocubes that resembles the formation and development of latent image centers in silver halide grains in the photographic process is formulated.
Abstract: It remains a challenge to synthesize Ag nanocubes in an aqueous system, although the polyol process was successfully adopted more than one decade ago. Here, we report an aqueous method for the synthesis of Ag nanocubes with an average edge length of 35–95 nm. It involves the formation of AgCl octahedra by mixing CF3COOAg with cetyltrimethylammonium chloride, followed by the nucleation and growth of Ag nanocrystals in the presence of ascorbic acid (AA) and FeCl3. The Fe3+/Fe2+ redox pair is responsible for the removal of multiply twinned seeds through oxidative etching. The Cl– ions play two critical roles in the nucleation and growth of Ag nanocubes with a single-crystal structure. First, the Cl– ions react with Ag+ ions to generate nanometer-sized AgCl octahedra in the initial stage of a synthesis. In the presence of room light and a proper reducing agent such as AA, the AgCl can be reduced to generate Agn nuclei followed by their evolution into single-crystal seeds and then Ag nanocrystals. Second, the ...

139 citations

Journal ArticleDOI
TL;DR: In this article, a template-engaged topotactic reaction was used to synthesize single-crystalline Ag2Se nanowires from trigonal selenium.
Abstract: Single-crystalline Ag2Se nanowires have been successfully synthesized through a template-engaged topotactic reaction in which nanowires of trigonal selenium were transformed into Ag2Se by reacting with aqueous AgNO3 solutions at room temperature (RT). An interesting size-dependent transition between two crystal structures has also been observed for this newly synthesized one-dimensional system: The Ag2Se nanowires adopted a tetragonal structure when their diameters were less than ∼40 nm; an orthorhombic structure was found to be more favorable as the diameter of these nanowires was increased beyond 40 nm. Since this reaction can be carried out at ambient pressure and temperature, it should be straightforward to scale up the entire process for the high-volume production of Ag2Se nanowires with well-controlled sizes and crystal structures. These highly uniform nanowires of single-crystalline Ag2Se are potentially useful as photosensitizers, superionic conductors, magnetoresistive compounds, or thermoelectric materials. This work also represents the first demonstration of a template-engaged process capable of generating single-crystalline nanowires from the solution-phase and at RT.

139 citations

Journal ArticleDOI
TL;DR: Inorganic nanoribbons can be attached to an elastic surface at selected positions to make wave-like structures that maintain their semiconducting properties when stretched or compressed and will prove to be immediately useful in flexible electronics.
Abstract: Inorganic nanoribbons can be attached to an elastic surface at selected positions to make wave-like structures that maintain their semiconducting properties when stretched or compressed. These nanostructures will prove to be immediately useful in flexible electronics.

137 citations


Cited by
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01 May 1993
TL;DR: 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.
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.

29,323 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组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�ly.
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。

18,940 citations

Journal ArticleDOI
TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
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

11,752 citations