Triterpenoid contents and anti-inflammatory properties of the methanol extracts of ligustrum species leaves

Ligustrum (privet) plants are used by Chinese physicians to prevent and cure hepatitis and chronic bronchitis. Three common Ligustrum plant spp., namely Ligustrum lucidum Ait. (LL), L. pricei Hayata (LP) and L. sinensis Lour. (LS) were collected to assess their analgesic/anti-inflammatory properties on chemical-induced nociception and carrageenan-induced inflammation in rodents. The methanol extracts from Ligustrum plants leaves effectively inhibited nociceptive responses induced by 1% acetic acid and 1% formalin. LP and LL reduced the edema induced by 1% carrageenan. LP exhibited the best potency of the Ligustrum plants. Furthermore, LP reduced the abdominal Evan's blue extravasations caused by lipopolysaccharide, lipoteichoic acid, autocrines and sodium nitroprusside. The triterpenoid content of the three Ligustrum spp. was measured by high performance liquid chromatography using a photodiode array detector. LP contained the highest content of amyrin, betulinic acid and lupeol. LL had the highest content of oleanolic acid and ursolic acid. The various degrees of analgesic/anti-inflammatory effects among three Ligustrum plants may be related to their different triterpenoid contents. LP is a potential analgesic and anti-inflammatory Ligustrum plant. The effects of LP are partially related to the inhibition of cyclooxygenase-2 activity and a decrease in microvascular permeability via the actions of autocrines and kinins.     

Enantiotropic Nematics From Cross‐Like 1,2,4,5‐Tetrakis(4′‐alkyl‐4‐ethynylbiphenyl)benzenes and Their Biaxiality Studies

The theoretically predicted optimum length/breadth/width ratio for maximizing shape biaxiality was investigated experimentally by the facile and successful synthesis of cross‐shaped compound 3 , which showed enantiomeric nematic phase behavior. This cross‐like core structure could alternatively be viewed as two fused V‐shaped mesogens, which have recently immerged as a new direction in biaxial nematic research, at the bending tips that can act as a new structure for biaxial investigations. Whilst the thermal analysis data of compound 3 did not meet the expected theoretical values for biaxial nematics, surface‐induced biaxiality was evidenced by optical studies. Cluster‐size analysis within the nematic phase of compound 3 revealed the formation of meta‐cybotactic nematics, which approached the cluster sizes of cybotactic nematics. The split small‐angle 2D X‐ray diffraction patterns of magnetic‐field‐aligned samples indicated that the nematic phase was composed of small smectic C‐like clusters with the tilting of molecules within the clusters. The wide‐temperature‐range enantiomeric nematic phase of cross‐like compound 3 enabled the molecular skeleton to serve as an alternative skeleton to bent‐rod mesogens, which exhibited nematic phases with the potential competition of transitions to higher‐order liquid‐crystalline phases and crystallization, for future biaxial investigations.     

Characterization of HF-PECVD a-Si:H thin film solar cells by using OES studies

Hydrogenated amorphous silicon (a-Si:H) films show considerable potential for the fabrication of thin film solar cells. In this study, the a-Si:H thin films have been deposited in a parallel-plate radio frequency (RF) plasma reactor fed with pure SiH₄. The plasma diagnostics were performed simultaneously during the a-Si:H solar cell deposition process using an optical emission spectrometer (OES) in order to study their correlations with growth rate and microstructure of the films. During the deposition, the emitting species (SiH*, Si*, H*) was analyzed. The effect of RF power on the emission intensities of excited SiH, Si and H on the film growth rate has been investigated. The OES analysis revealed a chemisorption-based deposition model of the growth mechanism. Finally, the a-Si:H thin film solar cell with an efficiency of 7.6% has been obtained.     

Room-temperature slow light with semiconductor quantum-dot devices

We demonstrate room-temperature slow light that is electrically and optically controllable by using a quantum-dot (QD) semiconductor optical amplifier (SOA) at zero and low bias below the transparency current. The absorption spectrum of the QD SOA exhibits a spectral dip with a corresponding group-index dispersion and group delay owing to coherent population oscillation caused by the interaction of pump and probe laser light near resonance of the first heavy-hole-conduction-state transition. At an optical pump power of approximately 0.3 mW inside the single-mode waveguide without current injection, a group-index change of 3.0 with a bandwidth of 2 GHz was measured. This group-index change can be controlled by injection of electrical current and by changing the optical pump power.     

Feedback-controlled forcing in hybrid LES/RANS

The computational cost of large eddy simulation (LES) increases rapidly with the Reynolds number when applied to attached boundary layers. This problem can be avoided by use of a Reynolds-averaged Navier–Stokes (RANS) model in the inner part of the boundary layer, which reduces the computational cost drastically. Such hybrid LES/RANS methods yield accurate results in general, but suffer from an artificial buffer layer and a shift in the velocity profile around the modeling interface. This velocity shift can be removed by use of additional forcing, but the results are very sensitive to the forcing amplitude.

The present paper proposes a feedback algorithm which efficiently finds the appropriate amplitude and thus yields accurate flow statistics. The feedback algorithm is relatively robust, both in that it is insensitive to the values of the parameters involved and that it yields accurate results with different forcing fields and for different Reynolds numbers. It is argued that the feedback algorithm is consistent with the underlying assumptions of hybrid LES/RANS and that it does not introduce additional empiricism into the method.     

General probabilistic approach to the filtration process

We show experimentally that clogging is basically a matter of the probability of the presence of particles. We describe this process as a function of the main variables of the process, namely, the ratio of particle to mesh hole size, the solid fraction, and the number of grains arriving at each mesh hole during one test, with the help of a simple model, the predictions of which are in very good agreement with our experimental data.     

A Simple Electrochemical Approach Based on Inexpensive Wall‐Jet Screen‐Printed Ring Disk Electrode to Evaluate Oxygen Reduction Catalysts

A simple electrochemical approach to evaluate oxygen reduction catalysts using an inexpensive screen‐printed ring disk carbon electrode system, consisting of a ring electrode deposited with MnO₂ and a disk electrode modified with the catalysts for study, is developed in this study. The as‐prepared MnO₂ is selective and sensitive for H₂O₂ oxidation in the presence of O₂ and is crucial to the proposed approach. By coupling with a wall‐jet electrochemical cell, the product generated from the reduction reaction at the disk electrode can effectively be monitored at the MnO₂‐deposited ring electrode. Model catalysts of nano‐Au and nano‐Pd representing 2e^? reduction of O₂ to H₂O₂ and 4e^? reduction to H₂O, respectively, were evaluated as electrode materials in oxygen reduction reaction to demonstrate the applicability of the proposed method.     

Upstream monotonic interpolation for scalar transport with application to complex turbulent flows

A new monotonic scheme for the approximation of steady scalar transport is formulated and implemented within a collocated finite-volume/pressure-correction algorithm for general turbulent flows in complex geometries. The scheme is essentially a monotonic implementation of the quadratic QUICK interpolation and uses a continuous and compact limiter to secure monotonicity. The principal purpose is to allow an accurate and fully bounded, hence stable, approximation of turbulence convection in the context of two-equation eddy viscosity and Reynolds stress transport modelling of two- and three-dimensional flows, both subsonic and transonic. Among other benefits, this capability permits an assessment to be made of the adequacy of approximating turbulence convection with first-order upwind schemes in conjunction with higher-order formulations for mean-flow properties—a widespread practice. The performance characteristics of the bounded scheme are illustrated by reference to computations for scalar transport, for a transonic flow in a Laval nozzle, for one separated laminar flow and for two separated turbulent flows computed with a non-linear RNG model and full Reynolds stress closure.