Yi Cui

Bio: Yi Cui is an academic researcher from Stanford University. The author has contributed to research in topics: Anode & Lithium. The author has an hindex of 220, co-authored 1015 publications receiving 199725 citations. Previous affiliations of Yi Cui include KAIST & University of California, Berkeley.

Electrospun metal nanofiber webs as high-performance transparent electrode.

Abstract: Transparent electrodes, indespensible in displays and solar cells, are currently dominated by indium tin oxide (ITO) films although the high price of indium, brittleness of films, and high vacuum deposition are limiting their applications. Recently, solution-processed networks of nanostructures such as carbon nanotubes (CNTs), graphene, and silver nanowires have attracted great attention as replacements. A low junction resistance between nanostructures is important for decreasing the sheet resistance. However, the junction resistances between CNTs and boundry resistances between graphene nanostructures are too high. The aspect ratios of silver nanowires are limited to ∼100, and silver is relatively expensive. Here, we show high-performance transparent electrodes with copper nanofiber networks by a low-cost and scalable electrospinning process. Copper nanofibers have ultrahigh aspect ratios of up to 100000 and fused crossing points with ultralow junction resistances, which result in high transmitance at low sheet resistance, e.g., 90% at 50 Ω/sq. The copper nanofiber networks also show great flexibility and stretchabilty. Organic solar cells using copper nanowire networks as transparent electrodes have a power efficiency of 3.0%, comparable to devices made with ITO electrodes.

Superconductivity in an infinite-layer nickelate

Abstract: The discovery of unconventional superconductivity in (La,Ba)2CuO4 (ref. 1) has motivated the study of compounds with similar crystal and electronic structure, with the aim of finding additional superconductors and understanding the origins of copper oxide superconductivity. Isostructural examples include bulk superconducting Sr2RuO4 (ref. 2) and surface-electron-doped Sr2IrO4, which exhibits spectroscopic signatures consistent with a superconducting gap3,4, although a zero-resistance state has not yet been observed. This approach has also led to the theoretical investigation of nickelates5,6, as well as thin-film heterostructures designed to host superconductivity. One such structure is the LaAlO3/LaNiO3 superlattice7–9, which has been recently proposed for the creation of an artificially layered nickelate heterostructure with a singly occupied $${d}_{{x}^{2}-{y}^{2}}$$ band. The absence of superconductivity observed in previous related experiments has been attributed, at least in part, to incomplete polarization of the eg orbitals10. Here we report the observation of superconductivity in an infinite-layer nickelate that is isostructural to infinite-layer copper oxides11–13. Using soft-chemistry topotactic reduction14–20, NdNiO2 and Nd0.8Sr0.2NiO2 single-crystal thin films are synthesized by reducing the perovskite precursor phase. Whereas NdNiO2 exhibits a resistive upturn at low temperature, measurements of the resistivity, critical current density and magnetic-field response of Nd0.8Sr0.2NiO2 indicate a superconducting transition temperature of about 9 to 15 kelvin. Because this compound is a member of a series of reduced layered nickelate crystal structures21–23, these results suggest the possibility of a family of nickelate superconductors analogous to copper oxides24 and pnictides25. Superconductivity is demonstrated in an infinite-layer nickelate similar to infinite-layer copper oxides, which is synthesized using soft- chemistry topotactic reduction of the perovskite precursor phase.

Engineering empty space between Si nanoparticles for lithium-ion battery anodes

Abstract: Silicon is a promising high-capacity anode material for lithium-ion batteries yet attaining long cycle life remains a significant challenge due to pulverization of the silicon and unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles Despite significant advances in nanostructured Si electrodes, challenges including short cycle life and scalability hinder its widespread implementation To address these challenges, we engineered an empty space between Si nanoparticles by encapsulating them in hollow carbon tubes The synthesis process used low-cost Si nanoparticles and electrospinning methods, both of which can be easily scaled The empty space around the Si nanoparticles allowed the electrode to successfully overcome these problems Our anode demonstrated a high gravimetric capacity (~1000 mAh/g based on the total mass) and long cycle life (200 cycles with 90% capacity retention)

Porous MoO2 Nanosheets as Non-noble Bifunctional Electrocatalysts for Overall Water Splitting.

Abstract: A porous MoO2 nanosheet as an active and stable bifunctional electrocatalyst for overall water splitting, is presented. It needs a cell voltage of only about 1.53 V to achieve a current density of 10 mA cm(-2) and maintains its activity for at least 24 h in a two-electrode configuration.

Aharonov–Bohm interference in topological insulator nanoribbons

Abstract: Topological insulators represent unusual phases of quantum matter with an insulating bulk gap and gapless edges or surface states. The two-dimensional topological insulator phase was predicted in HgTe quantum wells and confirmed by transport measurements. Recently, Bi(2)Se(3) and related materials have been proposed as three-dimensional topological insulators with a single Dirac cone on the surface, protected by time-reversal symmetry. The topological surface states have been observed by angle-resolved photoemission spectroscopy experiments. However, few transport measurements in this context have been reported, presumably owing to the predominance of bulk carriers from crystal defects or thermal excitations. Here we show unambiguous transport evidence of topological surface states through periodic quantum interference effects in layered single-crystalline Bi(2)Se(3) nanoribbons, which have larger surface-to-volume ratios than bulk materials and can therefore manifest surface effects. Pronounced Aharonov-Bohm oscillations in the magnetoresistance clearly demonstrate the coherent propagation of two-dimensional electrons around the perimeter of the nanoribbon surface, as expected from the topological nature of the surface states. The dominance of the primary h/e oscillation, where h is Planck's constant and e is the electron charge, and its temperature dependence demonstrate the robustness of these states. Our results suggest that topological insulator nanoribbons afford promising materials for future spintronic devices at room temperature.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

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。