Stressed Kinetics of Nanoemulsion Formulation Encapsulated Ropinirole with a Validated Ultra High Performance Liquid Chromatography–Synapt Mass Spectrometry (UPLC‐MS/MS ESI‐Q‐TOF)

A highly sensitive ultra high pressure liquid chromatography (UHPLC‐MSMS) method for estimation of ropinirole in rat brain homogenate and plasma has been validated. The method was successfully used for the degradation kinetics in different stress condition and regulated temperature. The chromatographic separation was achieved using isocratic mobile phase, consisting of acetonitrile–2mM ammoniumacetate (28:72 v/v; 0.25 mL min^?1). The mass spectrometer was operated in synapt mass spectrometry mode via positive electrospray ionization using the transitions m/z 260 → m/z 261 for ropinirole, and m/z 324.39 → m/z 262.161 as a parent ion of escitalopram (IS). The assay for ropinirole was linear over the range of 0.5–100 ng mL^?1 (r²; 0.999). The intra‐ and inter day precisions were less than 11.2% in terms of relative standard deviation (R.S.D.), and the accuracy was within ±6.4% in terms of relative error (RE). The mean extraction‐efficiency of QC samples (MQC, 8 ng/mL) was ≥80%. The lower limit of quantification (LLOQ) was 0.049 ng/mL where as lower limit of detection (LLOD) was 0.016 ng/mL. All the peaks of degradation were well resolved. The degradation kinetics of ropinirole, showed highest stability (t_1/2 256.66/h; t_0.9, 39.11/h) in acidic medium, lower stability in alkaline environment (t_1/2, 103.43/h; t_0.9, 15.76/h) and highly susceptible in oxidative environment (t_1/2, 21.58/h; t_0.9, 3.28/h). The applicability of this assay was demonstrated and successfully applied for pharmacokinetic profiling of ropinirole in Wister rat brain homogenate after intranasal administration.     

High yield synthesis of intrinsic, doped and composites of nano-zinc oxide using novel combinatorial method

A novel synthesis of the production of luminescent zinc oxide (ZnO), either in its intrinsic, metal, non-metal-doped or composite forms with high yield has been developed by parallel iterative techniques, within a combinatorial library prepared by the reduction of nitroarenes. The reduction of nitroarenes by aluminium/zinc dusts in alkaline medium (pH 10±2) forms azoxy compounds, whereas in acidic medium (pH 4.9±0.2) forms phenyl hydroxylamine and zinc/aluminium dust gets oxidised into respective hydroxide. Here, we demonstrate the reduction of nitroarenes at neutral pH (7.0±0.2), which forms intrinsic as well as doped ZnO at 50±5°C using zinc dust alone or mixtures of salts of several transition and non-transition metals in presence of 1:10 ratio of solvent and water. Interestingly, it is observed that the photoluminescence emission could be tuned in a wide range from 390 to 615 nm useful for many display related devices.     

Photoluminescence of 2-(2′-hydroxy-5′-methylbenzoyl)-1,5-diphenylpyrrole in aqueous and β-cyclodextrin environments: manifestation of open and closed conformers

Steady-state fluorometric studies have been performed on 2-(2′-hydroxy-5′-methylbenzoyl)-1,5-diphenylpyrrole (HMBDPP) in aqueous and aqueous β-cyclodextrin (β-CD) environments at ambient temperature. The fluorophore mostly shows a single emission in aqueous solution. Addition of β-CD to the aqueous solution of the fluorophore results in the development of another emission band at higher energy. The difference in the fluorometric behaviour is assigned to a remarkable change in the polarity of the microenvironment within the supramolecular structural environment compared to that of the bulk aqueous phase. Semi-empirical calculation (AM1-SCI) rules out the possibility of intramolecular proton transfer reaction in any of the S₀, S₁ and T₁ states of the fluorophore. It is proposed that HMBDPP exists mostly in the intermolecularly hydrogen-bonded form (open conformer) in aqueous solution while within β-CD environment, it is the intramolecularly hydrogen-bonded form (closed conformer) that predominates.     

A composite very large-scale neighborhood structure for the capacitated minimum spanning tree problem

The capacitated minimum spanning tree (CMST) problem is to find a minimum cost spanning tree in a network where nodes have specified demands, with an additional capacity constraints on the subtrees incident to a given source node s. The capacitated minimum spanning tree problem arises as an important subproblem in many telecommunication network design problems. In a recent paper, Ahuja et al. (Math. Program. 91 (2001) 71) proposed two very large-scale neighborhood search algorithms for the capacitated minimum spanning tree problem. Their first node-based neighborhood structure is obtained by performing multi-exchanges involving several trees where each tree contributes a single node. Their second tree-based neighborhood structure is obtained by performing multi-exchanges where each tree contributes a subtree. The computational investigations found that node-based multi-exchange neighborhood gives the best performance for the homogenous demand case (when all nodes have the same demand), and the tree-based multi-exchange neighborhood gives the best performance for the heterogeneous demand case (when nodes may have different demands). In this paper, we propose a composite neighborhood structure that subsumes both the node-based and tree-based neighborhoods, and outperforms both the previous neighborhood search algorithms for solving the capacitated minimum spanning tree problem on standard benchmark instances. We also develop improved dynamic programming based exact algorithms for searching the composite neighborhood.     

Cohomology of the moduli of parabolic vector bundles

The purpose of this paper is to compute the Betti numbers of the moduli space ofparabolic vector bundles on a curve (see Seshadri [7], [8] and Mehta & Seshadri [4]), in the case where every semi-stable parabolic bundle is necessarily stable. We do this by generalizing the method of Atiyah and Bott [1] in the case of moduli of ordinary vector bundles. Recall that (see Seshadri [7]) the underlying topological space of the moduli of parabolic vector bundles is the space of equivalence classes of certain unitary representations of a discrete subgroup Γ which is a lattice in PSL (2,R). (The lattice Γ need not necessarily be co-compact). While the structure of the proof is essentially the same as that of Atiyah and Bott, there are some difficulties of a technical nature in the parabolic case. For instance the Harder-Narasimhan stratification has to be further refined in order to get the connected strata. These connected strata turn out to have different codimensions even when they are part of the same Harder-Narasimhan strata. If in addition to ‘stable = semistable’ the rank and degree are coprime, then the moduli space turns out to be torsion-free in its cohomology. The arrangement of the paper is as follows. In § 1 we prove the necessary basic results about algebraic families of parabolic bundles. These are generalizations of the corresponding results proved by Shatz [9]. Following this, in § 2 we generalize the analytical part of the argument of Atiyah and Bott (§ 14 of [1]). Finally in § 3 we show how to obtain an inductive formula for the Betti numbers of the moduli space. We illustrate our method by computing explicitly the Betti numbers in the special case of rank = 2, and one parabolic point.     

A facile tandem double-dehydrative-double-Heck olefination strategy for pot-economic synthesis of (E)-distyrylbenzenes as multi-target-directed ligands against Alzheimer's disease employing C. elegans model

A concise, one pot and regioselective access to (E)-distyrylbenzenes (DSBs) from arylhalide and secondary phenylenediethanol, a stable precursor for in situ generation of divinylbenzene (DVB) to avoid its polymerization, is described for construction of double CC bond formation via tandem double-dehydrative-double-Heck (D-D-D-H) reaction using Palladium and ionic liquid [hmim]Br as a cooperative catalyst. It is noteworthy that this pot-economy approach also provides direct synthesis of hydroxylated distyrylbenzenes without requirement of protection-deprotection strategy. Importantly, the synthesized DSBs are tested for their protective activity against β amyloid reduction, acetylcholine esterase inhibition, lipid lowering and reactive oxygen species (ROS) reduction properties in transgenic Caenorhabditis elegans model wherein 1,3-bis((E)-4-(trifluoromethyl)styryl)benzene (5c) is found to be active across all above factors thus presenting lead molecule within multi-target-directed ligands (MTDLs) approach. Molecular docking studies were also performed to understand the interactions of potent DSBs with receptors.     

Intercalation Compounds of Cu2+ and Nl2+ — Exchanged Montmorillonite Clay with 8-Hydroxyquinoline

Montmorillonite clay mineral shows remarkable ion exchange, intercalation and swelling properties. It can act as a good host for large organic molecules. Intercalated coordination compounds can be prepared in the interlayer spaces of montmorillonite structure. Cu(II)- and Ni(II)- exchanged montmorillonite sorb 8-hydroxyquinoline (oxine) to form corresponding coordination compounds of the exchanged metal ions. Such compounds have been characterised by means of elemental analysts, infrared spectroscopy, magnetic susceptibility data and X-ray diffraction. These compound show good thermal stability.