6,353 research outputs found
Current rectification by asymmetric molecules: An ab initio study
We study current rectification effect in an asymmetric molecule
HOOC-CH-(CH) sandwiched between two Aluminum electrodes using
an {\sl ab initio} nonequilibrium Green function method. The conductance of the
system decreases exponentially with the increasing number of CH. The
phenomenon of current rectification is observed such that a very small current
appears at negative bias and a sharp negative differential resistance at a
critical positive bias when . The rectification effect arises from the
asymmetric structure of the molecule and the molecule-electrode couplings. A
significant rectification ratio of 38 can be achieved when .Comment: to appear in J. Chem. Phy
A Supervised STDP-based Training Algorithm for Living Neural Networks
Neural networks have shown great potential in many applications like speech
recognition, drug discovery, image classification, and object detection. Neural
network models are inspired by biological neural networks, but they are
optimized to perform machine learning tasks on digital computers. The proposed
work explores the possibilities of using living neural networks in vitro as
basic computational elements for machine learning applications. A new
supervised STDP-based learning algorithm is proposed in this work, which
considers neuron engineering constrains. A 74.7% accuracy is achieved on the
MNIST benchmark for handwritten digit recognition.Comment: 5 pages, 3 figures, Accepted by ICASSP 201
Diterpene Synthases and Their Responsible Cyclic Natural Products
This review provides an overview of diterpene synthases which were initially identified via genetic and/or biochemical means, traversing all organisms researched to date
Systematic investigation of the rotational bands in nuclei with using a particle-number conserving method based on a cranked shell model
The rotational bands in nuclei with are investigated
systematically by using a cranked shell model (CSM) with the pairing
correlations treated by a particle-number conserving (PNC) method, in which the
blocking effects are taken into account exactly. By fitting the experimental
single-particle spectra in these nuclei, a new set of Nilsson parameters
( and ) and deformation parameters ( and
) are proposed. The experimental kinematic moments of inertia
for the rotational bands in even-even, odd- and odd-odd nuclei, and the
bandhead energies of the 1-quasiparticle bands in odd- nuclei, are
reproduced quite well by the PNC-CSM calculations. By analyzing the
-dependence of the occupation probability of each cranked Nilsson
orbital near the Fermi surface and the contributions of valence orbitals in
each major shell to the angular momentum alignment, the upbending mechanism in
this region is understood clearly.Comment: 21 pages, 24 figures, extended version of arXiv: 1101.3607 (Phys.
Rev. C83, 011304R); added refs.; added Fig. 4 and discussions; Phys. Rev. C,
in pres
Formation of Nanofoam carbon and re-emergence of Superconductivity in compressed CaC6
Pressure can tune material's electronic properties and control its quantum
state, making some systems present disconnected superconducting region as
observed in iron chalcogenides and heavy fermion CeCu2Si2. For CaC6
superconductor (Tc of 11.5 K), applying pressure first Tc increases and then
suppresses and the superconductivity of this compound is eventually disappeared
at about 18 GPa. Here, we report a theoretical finding of the re-emergence of
superconductivity in heavily compressed CaC6. The predicted phase III (space
group Pmmn) with formation of carbon nanofoam is found to be stable at wide
pressure range with a Tc up to 14.7 K at 78 GPa. Diamond-like carbon structure
is adhered to the phase IV (Cmcm) for compressed CaC6 after 126 GPa, which has
bad metallic behavior, indicating again departure from superconductivity.
Re-emerged superconductivity in compressed CaC6 paves a new way to design
new-type superconductor by inserting metal into nanoporous host lattice.Comment: 31 pages, 12 figures, and 4 table
Anti-obesity effect of an isoflavone fatty acid ester on obese mice induced by high fat diet and its potential mechanism
<p>Abstract</p> <p>Background</p> <p>The novel compound <b>1a </b>is one of the isoflavone fatty acid esters. In order to investigate the anti-obesity effect of compound <b>1a </b>and its potential mechanism of influence in adipocyte differentiation, Obese male C57BL/6J mice induced by high-fat diet (HFD) and rat preadipocytes (3T3-L1 cell) were used.</p> <p>Methods</p> <p>After 4-week HFD induction, the obese model was made successfully. After treatment with compound <b>1a</b>, mice plasma biochemistry parameters were analyzed. In addition, mice hepatic tissue slice was observed. In <it>in vitro </it>research, 3T3-L1 cell differentiation by Oil-Red-O staining and adipocyte apoptosis was detected by flow cytometry.</p> <p>Results</p> <p>The <it>in vivo </it>results implied that compound <b>1a </b>significantly decreased the body weight, white adipose tissue weight of obesity mice(p < 0.05), reduced leptin and TG in plasma(p < 0.05), elevated HDL-C in serum(p < 0.05). The <it>in vitro </it>results suggested that compound <b>1a </b>could significantly suppress the adipocyte viability and lipid accumulation in the differentiation of preadipocyte, and induce apoptosis in both preadipocytes and mature adipocytes(p < 0.05).</p> <p>Conclusion</p> <p>Compound <b>1a </b>regulates serum lipid profiles, decreases adipose tissue mass and body weight gain by inducing adipocyte apoptosis in high fat diet induced mice. Thus, it may be used to treat obese patients with hypercholesterolemia and hypertriglyceridemia.</p
Effects of relative orientation of the molecules on electron transport in molecular devices
Effects of relative orientation of the molecules on electron transport in
molecular devices are studied by non-equilibrium Green's function method based
on density functional theory. In particular, two molecular devices, with the
planer Au and Ag clusters sandwiched between the Al(100) electrodes
are studied. In each device, two typical configurations with the clusters
parallel and vertical to the electrodes are considered. It is found that the
relative orientation affects the transport properties of these two devices
completely differently. In the Al(100)-Au-Al(100) device, the conductance
and the current of the parallel configuration are much larger than those in the
vertical configuration, while in the Al(100)-Ag-Al(100) device, an
opposite conclusion is obtained
Synthesis of novel tetravalent galactosylated DTPA-DSPE and study on hepatocyte-targeting efficiency in vitro and in vivo
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