Application of ionic-liquid supported cloud point extraction for the determination of microcystin-leucine-arginine in natural waters

A cloud point extraction method has been developed using an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMiM PF(6)) for the determination of a widely studied cyanotoxin (microcystin leucine-arginine, MCLR) in natural waters. Extraction parameters such as sample pH, extraction temperature, extraction time, the amount of ionic liquid and the amount of extraction volume were investigated and optimized to achieve the maximum extraction efficiency. The results obtained indicated a good linearity with the correlation coefficient of 0.995 over the range of 0.5-50 μg L(-1). The relative standard deviation (RSD) of the method was 7.5% (n=6). The calculated method detection limit was 0.03 μg L(-1) (n=6). The practical applicability of the technique was demonstrated by analyzing water samples (n=9) collected from three different sites in local reservoirs.     

Exploring a chemical encoding strategy for combinatorial synthesis using Friedel-Crafts alkylation

The use of scandium(III) triflate and ytterbium(III) triflate-catalysed Friedel-Crafts alkylation to insert a set of hydroxymethyl pyrrole amide tags (1b-i) on to polystyrene resins under mild conditions and the encoding of a split and mix peptide library is demonstrated.     

A Stress Tensor for Anti-de Sitter Gravity

We propose a procedure for computing the boundary stress tensor associated with a gravitating system in asymptotically anti-de Sitter space. Our definition is free of ambiguities encountered by previous attempts, and correctly reproduces the masses and angular momenta of various spacetimes. Via the AdS/CFT correspondence, our classical result is interpretable as the expectation value of the stress tensor in a quantum conformal field theory. We demonstrate that the conformal anomalies in two and four dimensions are recovered. The two dimensional stress tensor transforms with a Schwarzian derivative and the expected central charge. We also find a nonzero ground state energy for global AdS₅, and show that it exactly matches the Casimir energy of the dual super Yang–Mills theory on S ³×R. Received: 20 April 1999 / Accepted: 8 July 1999     

Water soluble,conjugated main chain azo polymer: Synthesis and characterization

The monomer 2,5-diaminobenzenesulfonic acid has been polymerized to a high molecular weight, conjugated main chain azo polymer. The presence of the azo group in the polymer was confirmed using Raman spectroscopy. The polymer is highly soluble in water over a wide pH range. It is also soluble in common polar organic solvents such as N,N-dimethylformamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.     

Self-assembled second order nonlinear optical multilayer azo polymer

An epoxy based polymer with nonlinear optical azo chromophores was designed to contain anionic groups to induce water solubility and self assembly. Using this polyanion with a polycation, multilayers were prepared on a glass substrate by alternating adsorption from dilute aqueous solutions. The azo chromophores in the confined layer of the polyanion in the multilayer films self-assemble into a noncentrosymmetric alignment and demonstrate second order optical nonlinearity (d₃₃ = 19 pm/V).     

Evaluation of Nutritional Substances and Investigation of Antioxidant and Antimicrobial Potentials of Boerhavia diffusa with in Silico Molecular Docking

Boerhavia diffusa L. Nyctanginaceae (B. diffusa) is a medicinal herb commonly considered as a weed. The exploration of phytochemicals in different parts of B. diffusa with different solvents will create awareness, along with the suitable solvent and method for extraction of pharmaceutical compounds. Hence, the present study focuses on phytochemical analysis of B. diffusa leaves, stems, and roots in various solvents with hot and cold extraction. The decoctions performed well in most of the qualitative and quantitative tests, along with the DPPH assay. The aqueous extract showed a good result in the FRAP assay and ABTS assay. In the antimicrobial test, the B. diffusa root ethanol extract inhibited the growth of Pseudomonas aeruginosa and Staphylococcus aureus with zones of inhibition of about 8 mm and 20 mm at 200 µg concentration, respectively. Using a molecular docking approach, the top four ranked molecules from the crude extract of B. diffusa profiled from GC–MS spectroscopy in terms of growth inhibition of the pathogenic bacterium P. aeruginosa were selected; among them, 2-(1,2 dihydroxyethyl)-5-[[2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-3,4-dihydrochromen-6-yl]oxy]oxolane-3,4-diol exhibited the minimum binding score, revealing high affinity in complex. B. diffusa is highly nutritious, and the maceration and decoction extracts were similar except for the chloroform extract that was found to be weak.     

ChemInform Abstract: Electronic States of Al3P2, Al2P3, and Their Ions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Emerging Strategies in Stimuli-Responsive Silk Architectures

The utilization of implantable devices beseeches highly invasive surgeries considering the adversaries in the insertion of large, impliable devices through the body channels, which necessitate the development of implantable devices using biocompatible shape memory polymers. Silk displays prodigious heterogeneity in its genetic structure and physical properties in accordance with the spinning and storage process, where proteins undergo folding and unfolding. The stimuli-responsive nature of silk can be explained with the help of the structural morphology and composition of the material, where the hydrogen bonds in β-sheet domains and amorphous region act as switch points and net points, respectively. This review provides a primary attempt to enswathe all the literature available to date on the stimuli-responsive nature of silk and silk-based materials as a natural and biodegradable alternative for commercially used synthetic shape memory materials taking their elastomeric nature and reduction in glass transition temperature into account. Further constitutive model using the continuum approach has been utilized to explain the anisotropic elasticity damping effect and plastic deformation based on the α-helix chains, β-sheets, and β-spiral structures. The practicability to develop biomedical devices such as patient-specific-injectable scaffolds, drug carriers, and artificial muscles has been encompassed in this article.