Analysis of ethanol and methanol in human body fluids by headspace solid phase microextraction coupled with capillary gas chromatography.

A new method for extraction and analysis of ethanol and methanol in human whole blood, urine and saliva samples based on headspace solid phase microextraction (SPME) using silver sulfide (Ag(2)S) and polyvinyl chloride (PVC) coated on silver wire is described. Unlike commercial fibers, which are coated on fused silica, the proposed fiber has a metallic base to which the coating adheres very strongly. Due to metallic base, this fiber is very durable and is thermally stable up to 250 degrees C. After optimization of coating composition and microextraction conditions, the fiber was used for sampling of methanol and ethanol from human body fluids prior to capillary gas chromatographic analysis. The high recovery (>94%), low detection limits (5.6 mg/L for ethanol and 12.8 mg/L for methanol) and excellent linearity (>0.9900) of calibration graphs made the proposed method suitable for this purpose.     

Foliations transverse to fibers of Seifert manifolds

In this paper we prove the conjecture of Jankins and Neumann [JN2] about rotation numbers of products of circle homeomorphisms, which together with other results of [EHN] and [JN2] (mentioned below) implies that a Seifert manifold admits foliations tranverse to its fibers only if it admits such foliations with a projective transverse structure. 1991Mathematics Subject Classification: Primary 55R05, 57R30, Secondary 47A35, 57M99, 58F11. Partially supported by a Sloan Doctoral Dissertation Fellowship, and by the Technion-Israel Institute of Technology.     

Vibration analysis and design optimization of viscoelastic sandwich cylindrical shell

Damping properties of viscoelastic sandwich structure can be improved by changing some parameters such as thickness of the layers, distribution of partial treatments, slippage between layers at the interfaces, cutting and its distribution at the top and core layers. Since the optimization problem may result in a thick core layer, for achieving more accuracy a new higher-order Taylor's expansion of transverse and in-plane displacement fields is developed for the core layer of sandwich cylindrical shell in which the displacement fields at the core layer are compatibly described in terms of the displacement fields at the elastic faces. The presented model includes fewer parameters than the previously developed models and therefore decreases the number of degree of freedom in the finite element modeling. The transverse normal stress in the core layer is also considered. The formulations are developed to consider the slippage between layers at the interfaces. Finally, by combining the finite element method and the optimization algorithms based on the genetic algorithm and sequential quadratic programming technique, a design optimization methodology has been formulated to maximize the damping characteristics using the optimal number and location of cuts and partial treatments with optimal thicknesses of top and core layers.     

Green and effective route for the synthesis of monodispersed palladium nanoparticles using herbal tea extract (Stachys lavandulifolia) as reductant,stabilizer and capping agent,and their application as homogeneous and reusable catalyst in Suzuki coupling reactions in water

A simple and eco‐friendly procedure has been devised for the green synthesis of palladium nanoparticles, using the aqueous extract of herbal tea (Stachys lavandulifolia), a renewable and nontoxic natural phyto‐exudate. The water‐soluble components of the extract act as reducing agent and stabilizer. This green route does not require a surfactant or capping agent for the growth of palladium nanoparticles. The generated nanoparticles were analysed using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray analysis and inductively coupled plasma. The palladium nanoparticles having spherical shape and dimensions of between 5 and 7 nm were employed as a homogeneous catalyst for Suzuki coupling reactions conducted in water under mild conditions. Good yields of products, a facile work‐up, no evidence of leached palladium from the catalyst surface and smooth recovery of the catalysis by adding ethyl acetate, which could be reused at least eight times, confirm the very good efficiency of the catalytic reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

N-BROMOBIS(P-TOLUENESULFONYL)AMINE AS A NOVEL AND MILD REAGENT FOR CONVERSION OF OXIMES TO CARBONYL COMPOUND

N-Bromobis(p-toluenesulfonyl)amine (NBBTA) is a novel and efficient reagent for the conversion of oximes to their corresponding carbonyl compounds in good yields under mild conditions.     

Locating series FACTS devices for multi-objective congestion management improving voltage and transient stability

Transmission congestion management is a vital task in electricity markets. Series FACTS devices can be used as effective tools to relieve congestion mostly employing Optimal Power Flow based methods, in which total cost as the objective function is minimized. However, power system stability may be deteriorated after relieving congestion using traditional methods leading to a vulnerable power system against disturbances. In this paper, a multi-objective framework is proposed for congestion management where three competing objective functions including total operating cost, voltage and transient stability margins are simultaneously optimized. This leads to an economical and robust operating point where enough levels of voltage and transient security are included. The proposed method optimally locates and sizes series FACTS devices on the most congested branches determined by a priority list based on Locational Marginal Prices. Individual sets of Pareto solutions, resulted from solving multi-objective congestion management for each location of FACTS devices, are merged together to create the comprehensive Pareto set. Results of testing the proposed method on the well-known New-England test system are discussed in details and confirm efficiency of the proposed method.     

Calorimetric study of the oxidation of Al–Mg alloys for the prediction of healing of the double oxide film defect

The oxidation of Al alloys containing 0.3–4.5 wt% Mg in an atmosphere with a very low oxygen partial pressure (<0.5 ppm, to depict the atmosphere within a double oxide film defect) was studied using differential scanning calorimetry and scanning electron microscopy. The results showed that a newly formed Al₂O₃ layer held in an Al–Mg melt first transformed to MgAl₂O₄ spinel and then to MgO. This mechanism was the same for all the Al alloys containing 0.3–4.5 wt% Mg, but the kinetics of the transformations were different and depended on the Mg content of the melt. The results also suggest that the two layers of a double oxide film defect that is held in an Al melt containing 0.3–4.5 wt% Mg can heal (i.e. bond to each other) if held in the liquid metal for a long enough period of time.