Effects of postdeposition annealing on the dielectric properties of antiferroelectric lanthanum-doped lead zirconate stannate titanate thin films derived from pulsed laser deposition

Author name used in this publication: K. H. Wong2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Auto-ignition in turbulent combustion of hydrogen/air mixing layer at high pressure

The present work investigates the dynamic process of autoignition and extinction of flame kernels in a hydrogen/air mixing layer at a pressure of 30 atm. Direct numerical simulation (DNS) is conducted to solve the unsteady compressible flow equations coupled with reduced chemistry and detailed transport. The evolution of ignition kernels is tracked and analysed, focusing on the differences between successful and failed kernels. Parameters such as the temperature, heat release rate, scalar dissipation rate, convective and diffusive heat fluxes are calculated to provide quantitative information about ignition kernel development. The convective and diffusive heat fluxes in the successful and failed cases show marked differences. Finally, chemical explosive mode analysis (CEMA) is conducted to provide additional information

A compact skeletal mechanism for n-dodecane with optimized semi-global low-temperature chemistry for diesel engine simulations

A skeletal mechanism with 54 species and 269 reactions was developed to predict pyrolysis and oxidation of n-dodecane as a diesel fuel surrogate involving both high-temperature (high-T) and low-temperature (low-T) conditions. The skeletal mechanism was developed from a semi-detailed mechanism developed at the University of Southern California (USC). Species and reactions for high-T pyrolysis and oxidation of C5-C12 were reduced by using reaction flow analysis (RFA), isomer lumping, and then merged into a skeletal C0-C4 core to form a high-T sub-mechanism. Species and lumped semi-global reactions for low-T chemistry were then added to the high-T sub-mechanism and a 54-species skeletal mechanism is obtained. The rate parameters of the low-T reactions were tuned against a detailed mechanism by the Lawrence Livermore National Laboratory (LLNL), as well as the Spray A flame experimental data, to improve the prediction of ignition delay at low-T conditions, while the high-T chemistry remained unchanged. The skeletal mechanism was validated for auto-ignition, perfectly stirred reactors (PSR), flow reactors and laminar premixed flames over a wide range of flame conditions. The skeletal mechanism was then employed to simulate three-dimensional turbulent spray flames at compression ignition engine conditions and validated against experimental data from the Engine Combustion Network (ECN)

Neutrino Masses and Lepton-flavor-violating τ\tau Decays in the Supersymmetric Left-right Model

In the supersymmetric left-right model, the light neutrino masses are given by the Type-II seesaw mechanism. A duality property about this mechanism indicates that there exist eight possible Higgs triplet Yukawa couplings which result in the same neutrino mass matrix. In this paper, We work out the one-loop renormalization group equations for the effective neutrino mass matrix in the supersymmetric left-right model. The stability of the Type-II seesaw scenario is briefly discussed. We also study the lepton-flavor-violating processes ($\tau\to \mu\gamma$ and $\tau\to e\gamma$) by using the reconstructed Higgs triplet Yukawa couplings

Compact Chemical Mechanism for Autoignition and Combustion of Methylcyclohexane under Engine Relevant Conditions

A compact chemical kinetic mechanism for autoignition and combustion of methylcyclohexane (MCH) was developed and validated for a wide range of conditions, especially for low temperatures and high pressures that are most relevant to real engines. The mechanism was constructed in steps. An improved C5-C7 submechanism (26 species and 90 reactions) was first developed to describe fuel-cracking to form smaller fragments under high temperatures. Five modules of the C5-C7 submechanism were considered separately, and the rate constants were carefully estimated. A semiglobal low-temperature submechanism was developed to improve prediction of the negative temperature coefficient behaviors, which contained 4 species and 11 reactions. Isomers of intermediate radicals and fast reactions were lumped to obtain the minimal low-temperature submechanism. Combined with a simplified C0-C4 kernel (40 species and 276 reactions), the final mechanism consists of 70 species and 377 reactions. Validations of the newly developed mechanism were performed using amounts of experimental data, including ignition delays in shock tubes and rapid compression machines, under a wide range of temperatures (650–2000 K), pressures (1–50 atm), and equivalence ratios (0.5–2.0), and OH concentration histories in high pressure shock tubes. Furthermore, experimental data of species concentrations and flame speeds in laminar premixed flames were also used for validation. The present mechanism showed good accuracy in predicting ignition and combustion properties over a range of parameters. Simulations using other detailed MCH mechanisms were also carried out for comparison

Multiplexed, High Density Electrophysiology with Nanofabricated Neural Probes

Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC) performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable

Cellulose acetate phthalate, a common pharmaceutical excipient, inactivates HIV-1 and blocks the coreceptor binding site on the virus envelope glycoprotein gp120

BACKGROUND: Cellulose acetate phthalate (CAP), a pharmaceutical excipient used for enteric film coating of capsules and tablets, was shown to inhibit infection by the human immunodeficiency virus type 1 (HIV-1) and several herpesviruses. CAP formulations inactivated HIV-1, herpesvirus types 1 (HSV-1) and 2 (HSV-2) and the major nonviral sexually transmitted disease (STD) pathogens and were effective in animal models for vaginal infection by HSV-2 and simian immunodeficiency virus. METHODS: Enzyme-linked immunoassays and flow cytometry were used to demonstrate CAP binding to HIV-1 and to define the binding site on the virus envelope. RESULTS: 1) CAP binds to HIV-1 virus particles and to the envelope glycoprotein gp120; 2) this leads to blockade of the gp120 V3 loop and other gp120 sites resulting in diminished reactivity with HIV-1 coreceptors CXCR4 and CCR5; 3) CAP binding to HIV-1 virions impairs their infectivity; 4) these findings apply to both HIV-1 IIIB, an X4 virus, and HIV-1 BaL, an R5 virus. CONCLUSIONS: These results provide support for consideration of CAP as a topical microbicide of choice for prevention of STDs, including HIV-1 infection

Total flavonoid fraction of the Herba epimedii extract suppresses urinary calcium excretion and improves bone properties in ovariectomised mice

2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe