Mono- and binuclear ruthenium(II) trifluoroacetato complexes containing monodentate co-ligands

Summary The syntheses of new dinuclear and mononuclear complexes of Ru^II trifluoroacetate containing monodentate co-ligands, namely [Ru₂(-O₂CCF₃)₄L₂] (L = py, 2-Mepy or 3-Mepy); trans-[Ru(O₂CCF₃)₂L₄] (L = 2-Mepy or 3-Mepy); [Ru(O₂CCF₃)(PPh₃)₄](O₂CCF₃) and [Ru(O₂CCF₃)₂(CO)(MPh₃)₃] (M = P or As), are described. The complexes have been characterized by physical and electrochemical studies.     

A novel feature representation method based on Chou's pseudo amino acid composition for protein structural class prediction

During last few decades accurate determination of protein structural class using a fast and suitable computational method has been a challenging problem in protein science. In this context a meaningful representation of a protein sample plays a key role in achieving higher prediction accuracy. In this paper based on the concept of Chou's pseudo amino acid composition (Chou, K.C., 2001. Proteins 43, 246-255), a new feature representation method is introduced which is composed of the amino acid composition information, the amphiphilic correlation factors and the spectral characteristics of the protein. Thus the sample of a protein is represented by a set of discrete components which incorporate both the sequence order and the length effect. On the basis of such a statistical framework a simple radial basis function network based classifier is introduced to predict protein structural class. A set of exhaustive simulation studies demonstrates high success rate of classification using the self-consistency and jackknife test on the benchmark datasets.     

Microemulsion mediated in situ derivatization-extraction and gas chromatography-mass spectrometric analysis of alkylphosphonic acids

Detection and identification of environmental signatures of chemical warfare agents is an important aspect of verification program of Chemical Weapons Convention (CWC). Alkylphosphonic acids (APAs) are ultimate and persistent degradation products of nerve agents. Their identification in a sample submitted for off-site analysis infers possible indication of contamination with nerve agents. This paper describes the development of a new sample preparation method which involves 'in situ derivatization and extraction' (INDEX) of acids from water. Derivatization is performed by alkylation of APAs with alkylbromides in surfactant less microemulsion (SLME). The derivatized analytes were analyzed by gas chromatography coupled with mass spectrometry. The developed method involves simultaneous derivatization (alkylation) and extraction of acidic analytes mediated by surfactant less microemulsion. Various derivatization-extraction parameters such as solvent, reaction time and temperature, base and alkyl bromides were optimized. Pentyl bromide in the presence of potassium carbonate and diisopropylamine at 100 degrees C derivatized the selected acids efficiently. Kinetic data for alkylation of methylphosphonic acids and some carboxylic acids were obtained to assess their relative susceptibility for alkylation in microemulsion. Methylphosphonic acid and isopropyl methylphosphonic acid took 140-150 min to reach completion while carboxylic acids took 100 min to complete the reaction. INDEX could be successfully performed even in the presence of interfering Ca(2+) and Mg(2+) ions.     

Microwave-assisted,montmorillonite K-10 catalyzed three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free conditions

An efficient, rapid, and green synthesis of 2H-indazolo[2,1-b]phthalazine-triones has been accomplished under solvent-free conditions by the reaction of phthalhydrazide, aldehydes and 5,5-dimethylcyclohexane-1,3-dione. This approach exploits the synthetic potential of microwave irradiation and Montmorillonite K-10 combination and offers many advantages, such as excellent product yields, shorter reaction time, reusable catalyst, easy isolation of products, and environmentally benign reaction conditions.     

Effective viscosity of a concentrated suspension of composite porous spherical particles

Meccanica - We present an analytical study of the effective viscosity of concentrated suspension of porous spherical particles with a rigid core, under the creeping flow conditions. It is assumed...     

On the energy spectra of one-dimensional anharmonic oscillators

In this paper we present explicit and simple analytical formulae for the energy eigenvaluesE _n (λ) of one-dimensional anharmonic oscillators characterized by the potentials 1/2mω ² x ²+λx ^2α withα=2, 3 and 4. A simple intuitive criterion supplemented by the requirement of correct asymptotic behaviour, has been employed in arriving at the formulae. Our energy values over a wide range ofn andλ are in good agreement with the numerical values computed by earlier workers through very elaborate techniques. To our knowledge this is the first time that formulae of such wide validity have been given. The results for pure power oscillators are trivially obtained by going over to theω→0 limit. Approximate analytic expressions for the low order even moments ofx are also given.     

Critical point phenomena in the electrical resistivity of binary liquid systems: CS2 + CH3CN and CS2 + CH3NO2

Electrical resistance measurements are reported on the binary liquid mixtures CS₂ + CH₃CN and CS₂ + CH₃NO₂ with special reference to the critical region. Impurity conduction seems to be the dominant mechanism for charge transport. For the liquid mixture filled at the critical composition, the resistance of the system aboveT _c follows the relationR=R _c−A(T−T _c) ^b withb=0·6±0·1. BelowT _c the conductivities of the two phases obey a relation σ₂−σ₁=B(T _c−T)^β with β=0·34±0·02, the exponent of the transport coefficient being the same as the exponent of the order parameter, an equilibrium property.     

Electronic absorption spectra of MnO4− ions in single crystals of alums

The electronic absorption spectra of MnO₄^? ions in the single crystals of KA1(SO₄)₂·12H₂O and NH₄A1(SO₄)₂·12H₂O at room temperature and liquid nitrogen temperature are reported. The assignments of the absorption bands observed at around 5200 Å, 3600 Å, 3000 Å and 2300 Å have been made in a consistent manner. The molecular orbital energy level scheme given by Johnson and Smith on the basis of a spin-unrestricted SCF Xα cluster model has been used in conjunction with Slater's transition state theory to interpret the optical absorption spectra.     

Ferroelectric and phase transition studies in cesium nitrate: poly(vinyl?alcohol)?composite films

The composite films of cesium nitrate (CsNO₃) and poly(vinyl alcohol) (PVA) with varying composition were prepared using the solvent cast method. The hysteresis loop characteristics show optimum remnant polarization (P _r ) of 2.75 μC/cm² at 50 wt.% composition. The field emission scanning electron microscope images show a nearly homogeneous distribution of CsNO₃ grains in the 50 wt.% composite film. The temperature dependence of the remnant polarization shows a diffused transition temperature range from the ferroelectric to the paraelectric phase and this has been attributed to the reduced enthalpy. The butterfly features of the dielectric constant–voltage (ε–V) characteristics have been attributed to polarization switching.