A Molecular Mean Field Theory of Reentrant Phases

The observed phase transition sequence N-S_A-N_re S_re with a lowering in temperature in pure compounds of molecules with a strongly polar end group is reproduced in a mean field model which is taken as an extension of the McMillan potential. This model shows how the dimers in presence of space filling monomers can account for the high temperature S_A phase. As the temperature is lowered, more and more monomers form dimers leaving empty spaces and this initiates an intercalation of dimers belonging to the neighbouring layers. This intercalation is responsible for the lowering of the strength of layering interaction in a McMillan type potential and thus a reentrant nematic phase occurs. This model for the first time successfully accounts for the thickness of the low temperature smectic phase.     

Finite Diagonal Random Matrices

The goal of this article is to extend some results of Popescu (Probab. Theory Relat. Fields 144:179, 2009) in several directions. We establish the limiting spectral distribution (LSD) for r-diagonal matrices under reduced moment conditions compared to those required by Popescu. We also deal with the joint convergence of several sequences of such matrices. In particular, we show that there is a large class of such matrices where the joint limit is not free while the marginals are semicircular. We also consider matrices of the form $X_{n}X_{n}^{T}$ where X _n is a sequence of nonsymmetric r-diagonal random matrices and establish their limiting spectral distribution.     

Supramolecular Arrangement and DFT analysis of Zinc(II) Schiff Bases: An Insight towards the Influence of Compartmental Ligands on Binding Interaction with Protein

We report, for the first time, a detailed crystallographic study of the supramolecular arrangement for a set of zinc(II) Schiff base complexes containing the ligand 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol], where R=methyl/tert-butyl/chloro. The supramolecular study acts as a pre-screening tool for selecting the compartmental ligand R of the Schiff base for effective binding with a targeted protein, bovine serum albumin (BSA). The most stable hexagonal arrangement of the complex [Zn − Me] (R=Me) stabilises the ligand with the highest FMO energy gap (ΔE=4.22 eV) and lowest number of conformations during binding with BSA. In contrast, formation of unstable 3D columnar vertebra for [Zn − Cl] (R=Cl) tend to activate the system with lowest FMO gap (3.75 eV) with highest spontaneity factor in molecular docking. Molecular docking analyses reported in terms of 2D LigPlot+ identified site A, a cleft of domains IB, IIIA and IIIB, as the most probable protein binding site of BSA. Arg144, Glu424, Ser428, Ile455 and Lys114 form the most probable interactions irrespective of the type of compartmental ligands R of the Schiff base whereas Arg185, Glu519, His145, Ile522 act as the differentiating residues with ΔG=−7.3 kcal mol⁻¹.     

Correction to: Effect of Basil antioxidant additive on the performance,combustion and emission characteristics of used cooking oil biodiesel in CI engine

Journal of Thermal Analysis and Calorimetry - The solid–liquid equilibria (SLE) of two binary mixtures of organic stabilizers for energetic materials, viz....     

Photodynamic efficacy of chlorin p6: a pH dependent study in aqueous and lipid environment

Photodynamic efficacy of chlorin p6, a potential candidate of photodynamic therapy (PDT), has been studied at pH 5.0, 6.0 and 7.6 in aqueous and lipid environment. Increased chlorin p6 mediated photodynamic bleaching of N,N-dimethyl-4-nitrosoaniline (RNO), a measure of singlet oxygen yield, was obtained at higher pH. Rate of photodynamic bleaching of RNO was also higher at higher pH and the rate decreased with lowering in pH of irradiated solution. Photodynamic oxidation of tryptophan was also found to be higher at higher pH. Diminished oxidation of RNO was obtained with decrease in pH of irradiated solution. Both, RNO bleaching and tryptophan oxidation was significantly reduced by sodium azide, a known quencher of singlet oxygen. At lower pH, chlorin p6 mediated photodynamic malondialdehyde (MDA) and lipid hydroperoxide formation in egg lecithin liposome was higher. At higher pH chlorin p6 was found to be photodynamically more effective in aqueous environment whereas at lower pH chlorin p6 was photodynamically more effective in hydrophobic environment.     

Surfactant solubilization and the direct encapsulation of interfacially active phenols in mesoporous silicas

The solubilization of phenols in micelles of cetyltrimethyl ammonium bromide leads to microstructural changes from spherical micelles to wormlike micelles and then to vesicles. These microstructures are then used to template silicas. There is a transition from highly ordered hexagonal mesoporous silicas of the M41S family to lamellar structures, as the phenolic dopant concentration is increased. The results have implication to the removal of phenols from aqueous waste streams through the micellar enhanced ultrafiltration process. The entrapment of phenols in mesoporous silicas provides a way to sequester such contaminants in concentrated form.     

Methods developed for SELEX

SELEX (systematic evolution of ligands by exponential enrichment) is a process that involves the progressive purification from a combinatorial library of nucleic acid ligands with a high affinity for a particular target by repeated rounds of partitioning and amplification. With the development of aptamer technology over the last decade, various modified SELEX processes have arisen that allow various aptamers to be developed against a wide variety of molecules, irrespective of the target size. In the present review, the separation methods used in such SELEX processes are reviewed.     

Mathematical Modelling and Computer Simulation of Linear Polymer Degradation: Simple Scissions

Summary: Degradation of a polymer in a reactor by the degrading agent(s) follows a distinct pattern, primarily influenced by structural integrity and reactor environment. This distinct pattern is recorded in the changes in the evolved molecular weight distribution (MWD) or polymer chain length distribution (PCLD) curve characteristics from the initial intact state. Modern size exclusion chromatography (SEC) is the best laboratory‐based method that can clearly provide these plots in the form of chromatogram; however, detailed molecular information is not available. The nature of molecular destruction can be well‐characterised if the distinct MWD shift patterns can be simulated to fingerprint the different chain scission dynamics. This is investigated by our current research using the power of computer simulation techniques to gain insight into the polymer ageing processes. One such technique for studying simple decay processes is presented here, and the results are compared with experimental findings. The concept of a binary tree scission model is introduced to show chain rupture as a sequence of probabilistic events and as a non‐linear function of time. Two new mathematical algorithms, an iterative Monte Carlo structured probability scheme and a semi‐iterative algebraic exact statistical formulation method, are investigated to implement this model and simulate the evolution of resultant temporal MW distribution. The latter, an innovative approach to mathematical modelling, has the potential to generate a statistically perfect instant MWD decay curve. A statistical comparison of the product yield is presented from the data obtained using a wide variety of simulated scission regimes to determine the sources of variability.

Simulated MWD lateral shift for percent cut scission model showing deviation from the initial MWD (red) over degradation time zones T_j(0 ≥ j ≤ 9) with bimodal and curve broadening effect due to accumulation of varied percent cut range 5–30%.