Formulation and physicochemical characterization of microemulsion system using isopropyl myristate, medium-chain glyceride, polysorbate 80 and water

The phase behavior of the system isopropyl myristate/medium-chain glyceride/polysorbate 80/water forming both w/o and o/w microemulsions has been studied to develop microemulsion comprising of pharmaceutical excipients. The pseudo-ternary phase diagrams with large monophasic zones and gel formation were realized and several compositions were identified in the phase diagram for rheological, dynamic light scattering (DLS) and calorimetric measurements. The identified systems at different temperatures behaved as Newtonian fluid and the activation parameters for their viscous flow were evaluated. From DLS measurements, hydrodynamic diameter, polydispersity and diffusion coefficient of the microheterogeneous dispersions were determined. The free energy, enthalpy and entropy of solution of the w/o and o/w microemulsions were determined from calorimetric measurements.     

Shorted operators of partitioned matrices and application

In this paper, our main objective is to study the effect of appending/deleting a column/row on the shorted operators. It turns out that for matrices A and B for which the shorted operator S(A|B) exists, S(A₁|B₁) of the matrix A₁=[A:a] with respect to the matrix B₁=[B:b], when it exists, is obtained by appending a suitable column to S(A|B). Moreover, if S(A₁|B₁) exists, then S(A|B) exists and is obtained from S(A₁|B₁) by dropping its last column. In the process, we study the effect of appending/deleting a column/row on the space pre-order and the parallel sum of parallel summable matrices. Finally, we specialize to the case of and matrices and study the effect of bordering (by an additional column and a row) on the shorted operator. We conclude the paper with an application to Linear Models with singular dispersion structure.     

Complex dynamics of atomic clusters

Potential energy fluctuations in small atomic clusters have long-ranged temporal correlations, which lead to l/f noise in the power spectra. The relaxation dynamics in clusters has a hierarchical organization, resulting from different processes at the surface and core. A cellular dynamical model is proposed to understand the origin of such fluctuations.     

Tandem regioselective synthesis of tetrazoles and related heterocycles using iodine

A one-pot, tandem process has been developed for the synthesis of a library of tetrazoles from aryl isothiocyanates. Condensation of aryl isothiocyanates with ammonia, and aryl amines (R-NH(2)) provided mono, 1,3-disubstituted symmetrical and unsymmetrical thioureas, which on desulfurization with molecular iodine (I(2)) led to formation of the corresponding heterocumulene (cyanamides or carbodiimides). The in situ generated heterocumulene on subsequent treatment with sodium azide at room temperature gave corresponding tetrazoles. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas was found to be correlated with the basicities (pK(a)'s) of the parent amines attached to the thiourea. Aryl-sec-alkyl unsymmetrical thioureas gave thioamido guanidino products rather than the 5-aminotetrazoles produced by HgCl(2) mediation of the reaction. Bis-thioureas derived from aryl isothiocyanates and hydrazine gave thiadiazoles exclusively.     

Relativistic effects and gold site distributions: synthesis, structure, and bonding in a polar intermetallic Na6Cd16Au7

Na(6)Cd(16)Au(7) has been synthesized via typical high-temperature reactions, and its structure refined by single crystal X-ray diffraction as cubic, Fm ?3m, a = 13.589(1) ?, Z = 4. The structure consists of Cd(8) tetrahedral star (TS) building blocks that are face capped by six shared gold (Au2) vertexes and further diagonally bridged via Au1 to generate an orthogonal, three-dimensional framework [Cd(8)(Au2)(6/2)(Au1)(4/8)], an ordered ternary derivative of Mn(6)Th(23). Linear muffin-tin-orbital (LMTO)-atomic sphere approximation (ASA) electronic structure calculations indicate that Na(6)Cd(16)Au(7) is metallic and that ～76% of the total crystal orbital Hamilton populations (-ICOHP) originate from polar Cd-Au bonding with 18% more from fewer Cd-Cd contacts. Na(6)Cd(16)Au(7) (45 valence electron count (vec)) is isotypic with the older electron-richer Mg(6)Cu(16)Si(7) (56 vec) in which the atom types are switched and bonding characteristics among the network elements are altered considerably (Si for Au, Cu for Cd, Mg for Na). The earlier and more electronegative element Au now occupies the Si site, in accord with the larger relativistic bonding contributions from polar Cd-Au versus Cu-Si bonds with the neighboring Cd in the former Cu positions. Substantial electronic differences in partial densities-of-states (PDOS) and COHP data for all atoms emphasize these. Strong contributions of nearby Au 5d(10) to bonding states without altering the formal vec are the likely origin of these effects.     

Thermal,vibrational, and dielectric studies on PVP/LiBF4+ionic liquid [EMIM][BF4]-based polymer electrolyte films

Free-standing polymer electrolyte membranes based on poly(vinyl) pyrrolidone (PVP)/salt(LiBF₄) having different amounts of ionic liquid (IL) [EMIM][BF₄] were prepared and characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, and alternating current (AC) impedance spectroscopic techniques. The DSC results show a shift in T_m of PVP with salt/or IL content. TGA and DTGA (first derivative of TGA) results give evidence of the presence of uncomplexed PVP, PVP/salt, and PVP/IL complexes. Signatures of these entities are also present in the dielectric spectra. Complexation of PVP with salt and IL has been confirmed by FT-IR analysis. Electrical conductivity as a function of temperature has been studied for PVP/LiBF₄/IL [EMIM][BF₄]. Role of IL in changing phase transition, conductivity, and dielectric relaxation frequency has been discussed.     

Stabilization of betatron tune in Indus-2 storage ring

Indus-2 is a synchrotron radiation source that is operational at RRCAT, Indore, India. It is essentially pertinent in any synchrotron radiation facility to store the electron beam without beam loss. During the day to day operation of Indus-2 storage ring, difficulty was being faced in accumulating higher beam current. After examination, it was found that the working point was shifting from its desired value during accumulation. For smooth beam accumulation, a fixed desired tune in both horizontal and vertical plane plays a significant role in avoiding beam loss via the resonance process. This required a betatron tune feedback system to be put in the storage ring. After putting ON this feedback, the beam accumulation was smooth. The details of this feedback and its working principle are described in this paper.     

Pyridones as NNRTIs against HIV-1 mutants: 3D-QSAR and protein informatics

CoMFA and CoMSIA based 3D-QSAR of HIV-1 RT wild and mutant (K103, Y181C, and Y188L) inhibitory activities of 4-benzyl/benzoyl pyridin-2-ones followed by protein informatics of corresponding non-nucleoside inhibitors’ binding pockets from pdbs 2BAN, 3MED, 1JKH, and 2YNF were analysed to discover consensus features of the compounds for broad-spectrum activity. The CoMFA/CoMSIA models indicated that compounds with groups which lend steric-cum-electropositive fields in the vicinity of C5, hydrophobic field in the vicinity of C3 of pyridone region and steric field in aryl region produce broad-spectrum anti-HIV-1 RT activity. Also, a linker rendering electronegative field between pyridone and aryl moieties is common requirement for the activities. The protein informatics showed considerable alteration in residues 181 and 188 characteristics on mutation. Also, mutants’ isoelectric points shifted in acidic direction. The study offered fresh avenues for broad-spectrum anti-HIV-1 agents through designing new molecules seeded with groups satisfying common molecular fields and concerns of mutating residues.     

Supramolecular Association in the Structure of 2,9-<Emphasis Type="Italic">C</Emphasis>-<Emphasis Type="Italic">meso</Emphasis>-2,5,5,7,9,12,12,14-Octamethyl-1,8-diaza-4,11-diazoniacyclotetradecane as its Bis(nitrate) and Bis(acetate) Trihydrate

Abstract In the crystal structure of the nitrate salt, columns of di-cationic macrocycles, each disposed about a center of inversion, are interspersed by pairs of nitrate anions that form charged-assisted N–H···O hydrogen-bonding interactions, reinforced by C–H···O contacts. The topology of the resulting supramolecular architecture is that of a linear chain and these associate via further weak C–H···O contacts. In the structure of the acetate trihydrate, di-cationic macrocycles are circumscribed by 32-membered rings defined by O–H···O interactions, involving the acetate anions and solvent water molecules. Systematic variations in the geometric parameters in the molecular structures are correlated with the influence of intermolecular interactions. The nitrate crystallizes in the monoclinic space group P2₁/n with a = 8.3524(11) ?, b = 12.5497(16) ?, c = 11.1208(16) ?, β = 103.180(3)°, and Z = 2. The acetate trihydrate also crystallizes in the monoclinic space group P2₁/n with a = 9.6679(15) ?, b = 15.278(2) ?, c = 9.8376(18) ?, β = 106.068(5)°, and Z = 2. Index Abstract Supramolecular Association in the Structure of 2,9- C-meso -2,5,5,7,9,12,12,14-Octamethyl-1,8-diaza-4,11- diazoniacyclotetradecane as its Bis(nitrate) and Bis(acetate) Trihydrate Saroj K. S. Hazari, ⁽¹⁾ Tapashi G. Roy, ^(1)* Kanak K. Barua ⁽¹⁾ and Edward R. T. Tiekink ^(2)* A linear supramolecular chain stabilized by charge-assisted N–H···O hydrogen-bonding interactions is found in the nitrate salt. In the acetate trihydrate, di-cationic macrocycles are circumscribed by 32-membered rings constructed by O–H···O hydrogen-bonds. Supramolecular Association in the Structure of 2,9- C-meso -2,5,5,7,9,12,12,14-Octamethyl-1,8-diaza-4,11- diazoniacyclotetradecane as its Bis(nitrate) and Bis(acetate) Trihydrate Saroj K. S. Hazari, ⁽¹⁾ Tapashi G. Roy, ^(1)* Kanak K. Barua ⁽¹⁾ and Edward R. T. Tiekink ^{(2)* (1)}Department of Chemistry, University of Chittagong, Chittagong-4331, Bangladesh ⁽²⁾Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249-0698 Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

Effects of seasonal growth on ratio dependent delayed prey predator system

The Beddington–DeAngelis ratio dependent prey predator model with time delay has been discussed. The existence of Hopf bifurcation has been established. The numerical simulations have shown that seasonal growth and delay can give rise to variety of attractors including periodic, quasi-periodic as well as chaotic oscillations. The degree of complexity in the system increases with increase in magnitude of delay, or frequency of seasonal variation. The model parameters involved in functional response can also affect the complexity of the system.