Richard J. Saykally

Bio: Richard J. Saykally is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Spectroscopy & Absorption spectroscopy. The author has an hindex of 94, co-authored 457 publications receiving 40997 citations. Previous affiliations of Richard J. Saykally include University of California & Lawrence Berkeley National Laboratory.

Terahertz vibration-rotation-tunneling spectroscopy of the ammonia dimer: characterization of an out of plane vibration.

Abstract: The terahertz vibration-rotation-tunneling (VRT) spectrum of the ammonia dimer (NH(3))(2) has been measured between ca. 78.5 and 91.9 cm(-1). The dipole-allowed transitions are separated into three groups that correspond to the 3-fold internal rotation of the NH(3) subunits. Transitions have been assigned for VRT states of the A-A (ortho-ortho) combinations of NH(3) monomer states. The spectrum is further complicated by strong Coriolis interactions. K = 0 <-- 0, K = 1 <-- 0, K = 0 <-- 1, and K = 1 <-- 1 progressions have been assigned. The band origins, rotational constants, asymmetry doubling, centrifugal distortion, and Coriolis coupling constant have been determined from the fit to an effective Hamiltonian. These VRT transitions are tentatively assigned to an out of plane vibration with a K = 0 state at 89.141305(47) cm(-1), and a K = 1 state at 86.77785(9) cm(-1).

Terahertz VRT Spectroscopy of the Water Hexamer-h12 Cage: Dramatic Libration-Induced Enhancement of Hydrogen Bond Tunneling Dynamics

Abstract: We report the assignment and analysis of 176 transitions belonging to a librational band of the (H2O)6 cage isomer near 525 cm–1(15 THz). From a fit of the transitions to an asymmetric top model, we observe both dramatic changes in the rotational constants relative to the ground state, indicating significant nonrigidity, and striking enhancement in the tunneling motions that break and reform the hydrogen bonds in the cluster. This is the fifth water cluster system to display such an enhancement in the 15 THz librational region, the details of which may help to elucidate the hydrogen bond dynamics occurring in bulk liquid water.

Absorption spectroscopy: technique provides extremely high sensitivity.

Abstract: NASA: Technology associated with cavity ringdown laser absorption spectroscopy is reviewed. The technique is used to study general trace analysis, free radicals in flames and chemical reactors, molecular ions in electrical discharges, biological molecules and water clusters in supersonic jets, and vibrational overtones of stable molecules. Its specific enough to detect about 1-ppm fractional absorption by a gaseous sample in about 10 microseconds. The use of mirrors in ringdown sepctroscopy is explained. Other topics include the generation of pulsed infrared rays and the adaptation of ringdown spectroscopy for use with narrow-bandwidth continuous-wave lasers.

Method and apparatus for electrokinetic co-generation of hydrogen and electric power from liquid water microjets

Abstract: A method and apparatus for producing both a gas and electrical power from a flowing liquid, the method comprising: a) providing a source liquid containing ions that when neutralized form a gas; b) providing a velocity to the source liquid relative to a solid material to form a charged liquid microjet, which subsequently breaks up into a droplet spay, the solid material forming a liquid-solid interface; and c) supplying electrons to the charged liquid by contacting a spray stream of the charged liquid with an electron source. In one embodiment, where the liquid is water, hydrogen gas is formed and a streaming current is generated. The apparatus comprises a source of pressurized liquid, a microjet nozzle, a conduit for delivering said liquid to said microjet nozzle, and a conductive metal target sufficiently spaced from said nozzle such that the jet stream produced by said microjet is discontinuous at said target. In one arrangement, with the metal nozzle and target electrically connected to ground, both hydrogen gas and a streaming current are generated at the target as it is impinged by the streaming, liquid spray microjet.

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。

The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric Environment

Abstract: The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...

Dye-Sensitized Solar Cells

Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Abstract: 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.