On the integrable hierarchies associated with the N = 2 super Wn algebra

A new Lax operator is proposed from the viewpoint of constructing the integrable hierarchies related with the N = 2 super W_n algebra. It is shown that the Poisson algebra associated to the second Hamiltonian structure for the resulting hierarchy contains the N = 2 super Virasoro algebra as a proper subalgebra. The simplest cases are discussed in detail. In particular, it is proved that the supersymmetric two-boson hierarchy is one of the N = 2 supersymmetric KdV hierarchies. Also, a Lax operator is supplied for one of the N = 2 supersymmetric Boussinesq hierarchies.     

Modeling of pyridine synthesis process in a coupled fluidized bed reactor

To obtain the optimal operating conditions of a coupled reactor for pyridine synthesis, reactor modeling process is carried out in this paper. During the modeling process, the flow hydrodynamics, heat transfer behavior, inter-phase mass transfer behavior and reaction kinetics were taken into consideration consequently. Further, a regression program based on least square method was proposed to regress the model parameters. The prediction results agreed well with the experimental results with an average deviation of 5.9%. Finally, by setting suitable aim function, the optimal operating conditions of the coupled reactor for pyridine synthesis were determined.     

Rhodium dihydride complexes as models for the theoretical analysis of enantioselective hydrogenation reactions

A combination of molecular mechanics methods and extended Hückel calculations has been applied in order to have access to the more stable complexes expected to be involved as catalytic intermediates in the enantioselective hydrogenation of ketopantolactone (KPL) using chiral aminophosphine-phosphinite (AMPP) chlororhodium complexes. The product selectivity has been deduced from correlations between the prevailing configuration of the hydrogenated derivatives and the energetics of competing diastereomeric dihydride complexes of formula [RhCl(H)₂(AMPP)(KPL)] with the assumption that the enantioselectivity is controlled by the relative energies of such intermediates. The calculations have been obtained from the application of sequential and exhaustive search methodologies. The procedure has been applied to complexes bearing the aminophosphine-phosphinites (S)-Cp,Cp-ProNOP (IV) and (S)-Ph,Cp-ProNOP (V) and bis(aminophosphanes) derived from 2-(anilinomethyl)pyrrolidine (VI–IX). The latter induce a reversal of configuration of the major enantiomer of the hydrogenation product when varying specific substituents at the phosphorus atoms. Computations were carried out also for complexes bearing the two enantiomers (S)- and (R)-Ph,Cp-isoAlaNOP. The lowest energy complexes present enantiomeric structures. A novel insight into the local reactivity of the intermediates has been gained from determining the first migrating hydride according to the superdelocalizability parameter calculated for all isomers. Thus, the configurations of pantolactone arising from the alkoxyrhodium species obtained when assuming a nucleophilic attack of one of the hydrides to the carbonyl group of the ketone has been defined and are in total agreement with the experimental data.     

Markov-type fuzzy decision processes with a discounted reward on a closed interval

We formulate a new multi-stage decision process with Markov-type fuzzy transition, which is termed Markov-type fuzzy decision process. In the general framework of the decision process, both of state and action are assumed to be fuzzy itself. The transition of states is defined using the fuzzy relation with Markov property and the discounted total reward is described as a fuzzy number on a closed bounded interval. To discuss the optimization problem, a partial order of convex fuzzy numbers is introduced. In this paper the discounted total reward associated with an admissible stationary policy is characterized by a unique fixed point of the contractive mapping. Moreover, the optimality equation for the fuzzy decision model is derived under some continuity conditions. Also, an illustrated example is given to explain the theoretical results and the computation in the paper.     

Electronic absorption spectra of selenocarbonyl and thiocarbonyl compounds

Electronic absorption spectra of a variety of thiocarbonyl and selenocarbonyl compounds have been compared to point out their similarities. Interesting correlations between the absorption maxima and electronegativities of substituents in both the seleno- and thio-carbonyl compounds have been reported.     

New synthesis of 1-triacontanol

Succinic anhydride and behenic acid have been used to attach C₄ and C₂₂ carbon chains on to 2 and 5 positions of thiophene through two alternate acylation sequences. Raney nickel desulphurization to the 2,5-disubstituted thiophene yielded triacontanoic acid esters which on LAH reduction gave 1-triacontanol.     

Elemental analysis of bead samples using a laser-induced plasma at low pressure

An Nd:YAG laser (1064 nm, 8 ns, 30 mJ) was focused on various types of fresh, fossilized white coral and giant shell samples, including samples of imitation shell and marble. Such samples are extremely important as material for preparing prayer beads that are extensively used in the Buddhist faith. The aim of this research was to develop a non-destructive method to distinguish original beads from their imitations by means of spectral measurements of the carbon, hydrogen, sodium and magnesium emission intensities and by measuring the hardness of the sample using the ratio between Ca (II) 396.8 nm and Ca (I) 422.6 nm. Based on these measurements, original fresh coral beads can be distinguished from any imitation made from hard wood. The same technique was also effective in distinguishing beads made of shell from its imitation. A spectral analysis of bead was also performed on a fossilized white coral sample and the result can be used to distinguish to some extent the fossilized white coral beads from any imitation made from marble. It was also found that the plasma plume should be generated at low ambient pressure to significantly improve the hydrogen and carbon emission intensity and also to avoid energy loss inside the crater during laser irradiation at atmospheric pressure. The results of this study confirm that operating the laser-induced plasma spectroscopy at reduced ambient pressure offers distinct advantage for bead analysis over the conventional laser-induced breakdown spectroscopy (LIBS) technique operated at atmospheric pressure.     

Formic acid solubilization of marine biological tissues for multi-element determination by ETAAS and ICP–AES

A simple, fast method is described for the determination of Ag, As, Cd, Cu, Cr, Fe, Ni, and Se in marine biological tissues by electrothermal atomic-absorption spectrometry (ETAAS) and Na, Ca, K, Mg, Fe, Cu, and Mn by inductively coupled plasma–atomic emission spectrometry (ICP–AES). Solubilization of the biological tissue was achieved by using formic acid with vortex mixing followed by heating to 50°C in an ultrasonic bath. Once solubilized, the tissues were diluted to an appropriate volume with water for analysis. Aliquots were sampled into a graphite furnace and ICP–AES using a conventional autosampler. The method was validated by use of biological certified reference materials from NRC, DORM-2, DOLT-2, DOLT-3, LUTS-1, TORT-2, and NIST SRMs 1566b and 2976. Simplicity and reduced sample-preparation time prove to be the major advantages to the technique.     

Electrolyte additive maintains high performance for dendrite-free lithium metal anode

Because of their high capacity and low potential, lithium metal anodes are considered to be promising candidates for next generation electrode materials. However, the safety concerns and limited cycling life associated with uncontrollable dendrite growth hamper practical applications. In this work, the acidified cellulose ester, which is a mixed fiber microporous membrane film, was used as a novel electrolyte additive that effectively improves the cycle stability of the lithium metal anode and inhibits dendrite growth. The focus of this paper is on inhibiting the formation and growth of lithium dendrites. The coulombic efficiency of a Li|Cu battery with this acidified cellulose ester additive remains stable at 99% after 500 cycles under a current density of 1 mA/cm². Symmetric batteries also remain stable after 500 cycles (1000 h) under a current density of 1 mA/cm². These superior properties can be ascribed to the induced nucleation and the uniform distribution of lithium ion flux. This study uncovers an approach for effectively enabling stable cycling of dendrite-free lithium metal anodes.