9 research outputs found
Kaehler Manifolds of Quasi-Constant Holomorphic Sectional Curvatures
The Kaehler manifolds of quasi-constant holomorphic sectional curvatures are
introduced as Kaehler manifolds with complex distribution of codimension two,
whose holomorphic sectional curvature only depends on the corresponding point
and the geometric angle, associated with the section. A curvature identity
characterizing such manifolds is found. The biconformal group of
transformations whose elements transform Kaehler metrics into Kaehler ones is
introduced and biconformal tensor invariants are obtained. This makes it
possible to classify the manifolds under consideration locally. The class of
locally biconformal flat Kaehler metrics is shown to be exactly the class of
Kaehler metrics whose potential function is only a function of the distance
from the origin in complex Euclidean space. Finally we show that any rotational
even dimensional hypersurface carries locally a natural Kaehler structure,
which is of quasi-constant holomorphic sectional curvatures.Comment: 36 page
Crystal Structure of Methanobacterium thermoautotrophicum Phosphoribosyl-AMP Cyclohydrolase HisI
NRC publication: Ye
A structural genomics pilot project based on gene targets selected from Escherichia coli
A pilot project based on gene targets selected from the genome of E. coli has been initiated with 38 genes for initial cloning. Of these, 18 proteins have been purified to date and some crystals were obtained for twelve of them. Of these, four proteins yielded crystals diffracting to a sufficiently high resolution to warrant structural investigation. We have determined 3-D structures of three of these proteins using Se-Met labeling and MAD methods, while the structure of the fourth one was simultaneously determined by another group. To manage the parallel work on many proteins by several researchers it became necessary to create a searchable database containing the pertinent information about every stage of the work.NRC publication: Ye
Synergistically Enhanced Performance of Ultrathin Nanostructured Silicon Solar Cells Embedded in Plasmonically Assisted, Multispectral Luminescent Waveguides
Ultrathin silicon
solar cells fabricated by anisotropic wet chemical
etching of single-crystalline wafer materials represent an attractive
materials platform that could provide many advantages for realizing
high-performance, low-cost photovoltaics. However, their intrinsically
limited photovoltaic performance arising from insufficient absorption
of low-energy photons demands careful design of light management to
maximize the efficiency and preserve the cost-effectiveness of solar
cells. Herein we present an integrated flexible solar module of ultrathin,
nanostructured silicon solar cells capable of simultaneously exploiting
spectral upconversion and downshifting in conjunction with multispectral
luminescent waveguides and a nanostructured plasmonic reflector to
compensate for their weak optical absorption and enhance their performance.
The 8 μm-thick silicon solar cells incorporating a hexagonally
periodic nanostructured surface relief are surface-embedded in layered
multispectral luminescent media containing organic dyes and NaYF<sub>4</sub>:Yb<sup>3+</sup>,Er<sup>3+</sup> nanocrystals as downshifting
and upconverting luminophores, respectively, <i>via</i> printing-enabled
deterministic materials assembly. The ultrathin nanostructured silicon
microcells in the composite luminescent waveguide exhibit strongly
augmented photocurrent (∼40.1 mA/cm<sup>2</sup>) and energy
conversion efficiency (∼12.8%) than devices with only a single
type of luminescent species, owing to the synergistic contributions
from optical downshifting, plasmonically enhanced upconversion, and
waveguided photon flux for optical concentration, where the short-circuit
current density increased by ∼13.6 mA/cm<sup>2</sup> compared
with microcells in a nonluminescent medium on a plain silver reflector
under a confined illumination