Thermodynamic investigation of LiF-RbF system

Journal of Solid State Electrochemistry - The standard molar Gibbs energy of formation of LiRbF2(s) has been determined using an EMF technique. For this purpose, fluoride cell has been constructed...     

In vitro antioxidant potential of some soil fungi: screening of functional compounds and their purification from Penicillium citrinum

Fungal isolates (Aspergillus wentii 1, A. wentii 2, Penicillium citrinum, Penicillium granulatum) were selected to study their in vitro antioxidant potential by various assay procedures. Czapek–Dox’s medium was selected for the growth of fungi as it supported the best antioxidant activity based on their EC₅₀ values, P. citrinum was the best followed by P. granulatum, A. wentii 1, and A. wentii 2. The chromatographic analyses showed several compounds possessing antioxidant activity in the fungal extracts. Two such compounds were partially purified from P. citrinum which demonstrated potent antioxidant activity, equally effective or better than some of the standard antioxidants.     

Estimation of potential gains from mergers in multiple periods: a comparison of stochastic frontier analysis and Data Envelopment Analysis

A new dynamic Data Envelopment Analysis (DEA) approach is created to provide valuable managerial insights when assessing the merger performance. This new approach allows us to dynamically evaluate the pre-merger firms and the post-merger firm in a multi-period situation. A case study of bank branch merger is conducted to illustrate and validate the proposed approach. Both stochastic frontier analysis and data envelopment analysis are used and compared leading to highly correlated results. The computation show that merger results in an overall efficiency achievement in a banking industry.     

Clouding behaviour in surfactant systems

A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources.     

Cationic gold carbonyl complex on a phosphine support

A cationic gold carbonyl complex has been synthesized and characterized using several techniques including X-ray crystallography. [(Mes(3)P)Au(CO)][SbF(6)] (Mes = 2,4,6-Me(3)C(6)H(2)) has a linear, two-coordinate gold atom. This compound displays the CO stretching frequency at 2185 cm(-1). The (13)C NMR signal of the gold-bound (13)CO appears as a doublet centered at δ 182.6 ((2)J(C,P) = 115 Hz). A computational study shows that the Au-CO bond consists of electrostatic attraction, Au ← CO donation, and significant Au → CO π-back-bonding components. Polarization of the CO bond caused by the electrostatic effect of the cationic gold center is mainly responsible for the large blue shift in the CO stretching frequency.     

Experimental IR and Raman spectra and quantum chemical studies of molecular structures, conformers and vibrational characteristics of L-ascorbic acid and its anion and cation

IR and spectra of the L-ascorbic acid (L-AA) also known as vitamin C have been recorded in the region 4000-50 cm(-1). In order to make vibrational assignments of the observed IR and Raman bands computations were carried out by employing the RHF and DFT methods to calculate the molecular geometries and harmonic vibrational frequencies along with other related parameters for the neutral L-AA and its singly charged anionic (L-AA(-)) and cationic (L-AA(+)) species. Significant changes have been found for different characteristics of a number of vibrational modes. The four ν(O-H) modes of the L-AA molecule are found in the order ν(O(9)-H(10))>ν(O(19)-H(20))>ν(O(7)-H(8))>ν(O(14)-H(15)) which could be due to complexity of hydrogen bonding in the lactone ring and the side chain. The CO stretching wavenumber (ν(46)) decreases by 151 cm(-1) in going from the neutral to the anionic species whereas it increases by 151 cm(-1) in going from the anionic to the cationic species. The anionic radicals have less kinetic stabilities and high chemical reactivity as compared to the neutral molecule. It is found that the cationic radical of L-AA is kinetically least stable and chemically most reactive as compared to its neutral and anionic species.     

Inhibition of prefrontal protein synthesis following recall does not disrupt memory for trace fear conditioning

Background  

The extent of similarity between consolidation and reconsolidation is not yet fully understood. One of the differences noted is that not every brain region involved in consolidation exhibits reconsolidation. In trace fear conditioning, the hippocampus and the medial prefrontal cortex (mPFC) are required for consolidation of long-term memory. We have previously demonstrated that trace fear memory is susceptible to infusion of the protein synthesis inhibitor anisomycin into the hippocampus following recall. In the present study, we examine whether protein synthesis inhibition in the mPFC following recall similarly results in the observation of reconsolidation of trace fear memory.     

Projected Chvátal–Gomory cuts for mixed integer linear programs

Recent experiments by Fischetti and Lodi show that the first Chvátal closure of a pure integer linear program (ILP) often gives a surprisingly tight approximation of the integer hull. They optimize over the first Chvátal closure by modeling the Chvátal–Gomory (CG) separation problem as a mixed integer linear program (MILP) which is then solved by a general- purpose MILP solver. Unfortunately, this approach does not extend immediately to the Gomory mixed integer (GMI) closure of an MILP, since the GMI separation problem involves the solution of a nonlinear mixed integer program or a parametric MILP. In this paper we introduce a projected version of the CG cuts, and study their practical effectiveness for MILP problems. The idea is to project first the linear programming relaxation of the MILP at hand onto the space of the integer variables, and then to derive Chvátal–Gomory cuts for the projected polyhedron. Though theoretically dominated by GMI cuts, projected CG cuts have the advantage of producing a separation model very similar to the one introduced by Fischetti and Lodi, which can typically be solved in a reasonable amount of computing time. Gérard Cornuéjols was supported in part by NSF grant DMI-0352885, ONR grant N00014-03-1-0188, and ANR grant BLAN 06-1-138894. Matteo Fischetti was supported in part by the EU projects ADONET (contract n. MRTN-CT-2003-504438) and ARRIVAL (contract n. FP6-021235-2). Andrea Lodi was supported in part by the EU projects ADONET (contract n. MRTN-CT-2003-504438) and ARRIVAL (contract n. FP6-021235-2).     

Cobaloxime complexes containing imidazole and perchlorate or tetrafluoroborate anion

Summary Cobaloxime complexes containing the biologically active ligand imidazole and poorly coordinating anions, such as ClO ₄ ^– or BF ₄ ^– , have been synthesised. The perchlorate anion is not involved in coordination and there is evidence that [Co(DH)₂(L)₂]ClO₄ complexes are formed, whereas the tetrafluoroborate anion is involved in weak coordination giving complexes of the type [Co(DH)₂(L)(BF₄)] in the solid state. However, solvolysis of these latter complexes in solution yields 11 electrolytic species. The i.r. and electronic spectra, magnetic and conductivity measurements in nonaqueous media have been employed to characterise the complexes.Ligand abbreviations Py pyridine - Im imidazole - Me methyl - Al allyl - Vi vinyl