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.

Electrical resistance of the current collector controls lithium morphology

Abstract: The electrodeposition of low surface area lithium is critical to successful adoption of lithium metal batteries. Here, we discover the dependence of lithium metal morphology on electrical resistance of substrates, enabling us to design an alternative strategy for controlling lithium morphology and improving electrochemical performance. By modifying the current collector with atomic layer deposited conductive (ZnO, SnO2) and resistive (Al2O3) nanofilms, we show that conductive films promote the formation of high surface area lithium deposits, whereas highly resistive films promote the formation of lithium clusters of low surface area. We reveal an electrodeposition mechanism in which radial diffusion of electroactive species is promoted on resistive substrates, resulting in lateral growth of large (150 µm in diameter) planar lithium deposits. Using resistive substrates, similar lithium morphologies are formed in three distinct classes of electrolytes, resulting in up to ten-fold improvement in battery performance. Ultimately, we report anode-free pouch cells using the Al2O3-modified copper that maintain 60 % of their initial discharge capacity after 100 cycles, displaying the benefits of resistive substrates for controlling lithium electrodeposition.

Method and system for chalcogenide-based nanowire memory

Abstract: Chalcogenide-based nanowire memories are implemented using a variety of methods and devices. According to an example embodiment of the present invention, a method of manufacturing a memory circuit is implemented. The method includes depositing nanoparticles at locations on a substrate. Chalcogenide-based nanowires are created at the locations on the substrate using a vapor-liquid-solid technique. Insulating material is deposited between the chalcogenide-based nanowires. Lines are created to connect at least some of the chalcogenide-based nanowires.

A binder-free sulfur/carbon composite electrode prepared by a sulfur sublimation method for Li–S batteries

Abstract: A binder-free sulfur/carbon composite electrode was prepared by a sulfur sublimation method. Sulfur nanoparticles fill large pores in a carbon paper substrate and primarily have a monoclinic crystal structure. The composite electrode shows a long cycle life of over 200 cycles with good rate performance in Li–S batteries.

Real-Time Multiplex Kinase Phosphorylation Sensors in Living Cells

Abstract: Phosphorylation is an important post-translational modification implicated in cellular signaling and regulation. However, current methods to study protein phosphorylation by various kinases lack spatiotemporal resolution or the ability to simultaneously observe in real time the activity of multiple kinases in live cells. We present a peptide biosensor strategy with time correlated single photon counting-fluorescence lifetime imaging (TCSPC-FLIM) to interrogate the spatial and temporal dynamics of VEGFR-2 and AKT phosphorylation activity in real time in live 2D and 3D cell culture models at single cell resolution. By recording the increase in fluorescence lifetime due to a change in the solvatochromic environment of the sensor upon phosphorylation, we demonstrate that spatiotemporal maps of protein kinase activity can be obtained. Our results suggest that fluorescence lifetime imaging of peptide biosensors can be effectively and specifically used to monitor and quantify phosphorylation of multiple kinases ...

Towards electrically driven nanowire single-photon sources.

Abstract: A vapor–liquid–solid (VLS) growth of microwhiskers was developed by Wagner et al. in the 1960s. The recent re-examination of this method by the groups of Lieber, Yang, Samuelson, Wang, and others has resulted in the flourishing research into nanowires (NWs). Nearly all the IV, II– VI, III–V, and IV–VI semiconductor NWs can be synthesized. Ternary compound semiconductors have also been demonstrated. NWs can be made with complex shapes and form hyperbranched networks. A unique characteristic of NWs is that they can transport electrons, photons, and ions by a macroscopic distance along their length while maintaining a nanoscale size effect (quantum confinement, large surface area, etc.) across the diameter dimension. NWs and their derivatives are promising in many applications such as transistors, biosensors, 12] nanogenerators, nanofluidic channels, and light-emission deACHTUNGTRENNUNGvices. In the area of light-emission devices, NWs provide new exciting advantages over embedded quantum wires. First, NWs can be grown epitaxially on Si due to the facile strain relaxation within the small cross section of nanowires, which allows optical functions directly integrated onto mature Si technology. Second, NWs can be assembled in the form of cross arrays, which offer the flexibility of combining different materials to realize integrated multicolor emission. Third, NWs are not embedded in high-refractiveindex substrates, which significantly increases their light-extraction efficiency. With the above advantages, a new exciting opportunity would be to engineer NWs as singlephoton sources (SPSs). A SPS is a critical component for quantum information processing. 23] A SPS requires photon antibunching, that is, emission of a single photon at a time. To realize a SPS in NWs, it is necessary to engineering a small-sized quantum dot within a single NW. The introduction of growth techACHTUNGTRENNUNGniques such as chemical beam epitaxy into the VLS mechanism allows precise control of the heterostructure down to the nanometer scale, 12] which opens up the opportunity to perform quantum engineering within single NWs. Recently Borgstrcm et al. have described photon antibunching in photoluminescence measurements of GaP–GaAsP–GaP linear heterostructured NWs, in which the 15 nm GaAsP segment functions as a quantum dot. Surrounded by low-refractive-index air, these NW dots show intense singlephoton emission with a brightness typically an order of magnitude larger than self-assembled quantum dots. To take this a step forward, it would be highly desirable to develop electrically driven single-photon sources that do not require expensive lasers as excitation sources. Here we highlight the work by Minot et al. on singlequantum-dot NW LEDs, which show great promise towards electrically driven SPSs. A NW consisting of a narrow InAsP section sandwiched between n-InP and p-InP sections was grown by a Au-colloid-catalyzed VLS method in a metal–organic vapor phase epitaxy (MOVPE) chamber (Figure 1). The central InAsP section has a smaller bandgap, thus forming a potential well or quantum dots in the NWs, while the long InP section functions as electrical wiring for selectively injecting electrons or holes into the quantum dots. The central quantum dots need to be small enough to manifest the quantum confinement effects. Central InAsP sections as small as 12 nm have been realized by the authors. To characterize these heterostructure NWs, the authors have taken a step back to first study p–n junction InP NWs without the central InAsP quantum dot. They used different contact metals for selectively contacting with the pand n-type InP sections, which is necessary for efficient and type-selective charge-carrier injection. They found that Ti/Al makes an Ohmic contact with n-InP, and Ti/Zn/ Au is used as a contact for p-InP, but here there is a high [*] J. Zhu Department of Electrical Engineering, Stanford University 476 Lomita Mall, Stanford, California 94305 (USA)

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。