Determination of polyphenolic constituents and biological activities of bark extracts from different Pinus species

BACKGROUND: The most common commercially available pine bark extract is Pycnogenol^®, a standardised extract of Pinus maritima, which has been reported to have cardiovascular benefits and enhance microcirculation. The present study was conducted to determine the chemical composition of four pine bark extracts, assess their biological activities and to compare the results with Pycnogenol^®. RESULTS: The Pinus species were analysed by LC and LC‐MS; extracts of P. brutia and P. nigra showed higher levels of phenolic constituents compared to P. sylvestris and P. pinea. In particular, P. brutia contained extremely high concentrations of taxifolin (18.5%). The highest radical scavenging activities were attained with P. pinea (88.6%), P. nigra (87.2%) and P. brutia (86.4%) bark extracts. Additionally, anticarcinogenic effects of the extracts and their kinetics were determined in four cell lines including human prostate (PC‐3, DU 145, LNCaP) and breast adenocarcinoma (MCF7) by the MTT assay. Cell viability was reduced to 40% by extracts of P. pinea, and P. sylvestris in PC‐3 cells showing a similar effect like the positive control, CPT‐11. CONCLUSION: Pinus species other than P. maritima definitively possess high biological activities, and therefore present a huge potential to be utilised in the food and the pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

A complementary study on novel PdAuCo catalysts: Synthesis,characterization, direct formic acid fuel cell application,and exergy analysis

At present, Pd containing (10–40 wt%) multiwall carbon nanotube (MWCNT) supported Pd monometallic, Pd:Au bimetallic, and PdAuCo trimetallic catalysts are prepared via NaBH₄ reduction method to examine their formic acid electrooxidation activities and direct formic acid fuel cell performances (DFAFCs) when used as anode catalysts. These catalysts are characterized by advanced analytical techniques as N₂ adsorption and desorption, XRD, SAXS, SEM-EDX, and TEM. Electronic state of Pd changes by the addition of Au and Co. Moreover, formic acid electrooxidation activities of these catalysts measured by CV indicates that particle size changes in wide range play a major role in the formic acid electrochemical oxidation activity, ascribed the strong structure sensitivity of formic acid electrooxidation reaction. PdAuCo (80:10:10)/MWCNT catalyst displays the most significant current density increase. On the other hand, lower CO stripping peak potential obtained for PdAuCo (80:10:10)/MWCNT catalyst, attributed to the awakening of the Pd-adsorbate bond strength down to its optimum value, which favors higher electrochemical activity. DFAFCs performance tests and exergy analysis reveal that fuel cell performances increase with the addition of Au and Co which can be attributed to synergetic effect. Furthermore, temperature strongly influences the performance of formic acid fuel cell.     

Laser pumped light emitting diodes as broad area sources of coherent radiation

This paper describes the use of large area light emitting diodes, pumped with various laser sources, as extended area emitters of coherent radiation. The photon recycling takes place through the intermediary of electron–hole pair formation and subsequent stimulated recombination. It is possible to generate both spontaneous and stimulated emission together and the two channels are then independent of each other. This allows the generation of a mixture of coherent and non-coherent radiation in any desired proportion. The technique described is a broad-band resonant process with diffusive feedback and can be used for generating non-collimated laser radiation for a variety of applications.     

Thermal doping of rare-earth ions in gallium nitride

Doping of rare-earth ions in epitaxial gallium nitride material has been performed through a thermal diffusion process. The technique involves a brief photolytic etching of the surface followed by heating with a melt of rare-earth salt under reducing conditions. Europium-doped GaN pumped with above gap UV radiation showed strong red emission which was insensitive to a moderately strong magnetic field. The temperature dependence of the intensity of this red emission is also described. Neodymium caused surface pitting, through an unknown chemical mechanism, and consequent enhancement of defect-generated yellow luminescence.     

Three- and Two-Dimensional Finite-Element Computation of Inrush Current and Short-Circuit Electromagnetic Forces on Windings of a Three-Phase Core-Type Power Transformer

Although short-circuit current is frequently considered the major design fundamental for power transformers, experience with transformer failures shows that inrush currents that occur when transformers are energized can also cause serious damage. To investigate the resultant forces due to energizing power transformer windings, we modeled a three-phase, three-legged 66/11 kV, 40 MVA power transformer in two and three dimensions. We calculated electromechanical forces for short-circuit cases and also for inrush current through the windings, using the finite-element method. The results show that the forces exerted on the windings due to inrush current in many regions are larger than those due to short-circuit currents. Since the inrush current appears more frequently with a much longer duration compared to a short-current event, its harmful effects are worse than those of the short-circuit case.     

The effects of modified atmosphere gas composition on microbiological criteria, color and oxidation values of minced beef meat

This paper reports the effects of modified atmosphere gas compositions with different concentrations of CO(2)/O(2)/N(2) on color properties (L*, a* and b* values), oxidation stability (TBARS value) and microbiological properties of minced beef meat stored at +4 °C. Sampling was carried out on the 1st, 3rd, 5th, 7th, 9th, 11th and 14th day of storage. The gas mixtures used were as follows: (i) %30O(2) + %70CO(2) (MAP1), (ii) %50O(2) + %50CO(2) (MAP2), (iii) %70O(2) + %30CO(2) (MAP3), (iv) %50O(2) + %30CO(2) + %20N(2) (MAP4), and (v) %30O(2) + %30CO(2) + %40N(2) (MAP5). Control samples (AP) were packaged under atmospheric air. Pseudomonas, lactic acid bacteria, Brochothrix thermosphacta, and Enterobacteriaceae members were monitored. Among these five modified atmosphere gas compositions, the best preservation for minced beef meat was in MAP4 gas combination maintaining acceptable color together with oxidation stability and acceptable microbial loads until the end of storage period of fourteen days.     

Transient protein-protein interactions

Transient complexes are crucial for diverse biological processes such as biochemical pathways and signaling cascades in the cell. Here, we give an overview of the transient interactions; the importance of transient interactions as drug targets; and the structural characterization of transient protein-protein complexes based on the geometrical and physicochemical features of the transient complexes' interfaces. To better understand and eventually design transient protein-protein interactions (TPPIs), a molecular perspective of the protein-protein interfaces is necessary. Obtaining high-quality structures of protein-protein interactions could be one way of achieving this goal. After introducing the association kinetics of TPPIs, we elaborate on the experimental techniques detecting TPPIs in combination with the computational methods which classify transient and/or non-obligate complexes. In this review, currently available databases and servers that can be used to identify and predict TPPIs are also compiled.     

Synthesis of carbon coated nanocrystalline porous α-LiFeO2 composite and its application as anode for the lithium ion battery

In this work, we describe for the first time a high surface area nanocrystalline porous α-LiFeO₂-C composite anode material synthesized by a simple molten salt method, followed by a carbon coating process. The synthesized nanocomposite presents an interconnected porous architecture, as was confirmed by field emission scanning electron microscope observations. Transmission electron microscope investigations revealed that amorphous carbon was incorporated into the pores among the nanoparticles and that some nanoparticles were covered by a thin layer of amorphous carbon as well. Electrochemical measurements showed that the carbon played an important role, as it affected both the cycle life and the rate capability of the electrode. The α-LiFeO₂-C nanocomposite electrode delivered a higher reversible capacity and good cycle stability (540 mAh g⁻¹ at 1 C after 200 cycles) compared to the pure α-LiFeO₂ electrode. Good electrochemical performance of the α-LiFeO₂-C nanocomposite electrode could be attributed to the porous conductive architecture among the nanoparticles, which not only has benefits in terms of decreasing the absolute volume changes and increasing the mobility of lithium ions, but also offers conductive pathways along the whole interconnected wall in the structure, which is favourable for the transport of electrons, promotes liquid electrolyte diffusion into the bulk material, and acts as a buffer zone to absorb the volume changes. Our results indicate that α-LiFeO₂-C nanocomposite could be considered as a potential anode material for lithium-ion batteries.     

Optimum Design of Induction Motors for Electric Vehicles

This paper presents the design procedure of a three-phase squirrel-cage induction motor for electric vehicles. The procedure takes into account the requirements imposed by its use in vehicle traction. Also, the design considers the influence of the inverter by current and voltage harmonics. Because most of the requirements are antagonistic, the design procedure uses an objective function to select the optimal design. The objective function is a weighted summation of the motor losses and the motor volume. The objective function is then augmented with the design constraints. The modified Hooke-Jeeves search technique is adapted to solve this constrained nonlinear optimization problem. The influence of the "copper weight/iron weight" ratio on the motor design is studied and the optimum ratio is chosen in order to improve the performance of the motor.