Three-photon resonance enhanced excitation spectrum of atomic thallium

We present first measurements on the resonance enhanced three-photon excitation in thallium, using a Nd:YAG laser pumped dye laser in conjunction with a thermionic diode ion detector. The even-parity 6s²ns²S_1/2 (15 ? n ? 31) and nd ²D_5/2 (13 ? n ? 42) Rydberg states have been observed. The measured level energies reveal a dynamic shift from the photoabsorption values, which is decreasing with increasing n, while the asymmetry in the line profile is observed to be increasing with increasing n. In addition, an autoionising level (sp²⁴P_3/2) adjacent to the ionization threshold has been observed and quantitatively analyzed using the Fano’s photoionization cross-section relation for an isolated autoionising resonance.     

Synthesis, polymerization and Cu complexation studies of a new styrene derivative of 2-hydroxyacetophenone

A new 5-vinyl-2-hydroxyacetophenone monomer was synthesized using Heck reaction. The monomer was obtained by reacting 5-bromo-2-hydroxyacetophenone with ethylene in a palladium catalyzed reaction. Better yield was obtained at low concentration of the catalyst, high temperature and pressure of the ethylene gas. The monomer was homopolymerized and copolymerized with styrene using free radical solution polymerization techniques and investigated for reactivity ratio, retardation effect of the monomer on the polymerization of styrene. Homopolymer with average molecular weight of 40,391 was found to form binuclear complex with Cu²⁺. The complex was evident from shift in n-π^* transition from 332-378 nm in UV region and appearance of strong absorption at 1578 cm⁻¹ in the IR of the precipitated complex.     

Bacterial Lux-Fluoro test for biological assessment of pollutants in water samples from urban and rural origin

During the 20th century, population growth and urbanization, together with changes in production and consumption, have placed unprecedented demands on the quality of water. The ongoing extraordinary economic growth, industrialization, and urbanization of many developing countries results in widespread water pollution from agricultural, industrial, and domestic sources. In consequence, people consume contaminated drinking water, thereby increasing the risk of exposure not only to infectious and parasitic disease but also to a growing volume of genotoxic and cytotoxic chemicals. In light of these trends, new, rapid and low-cost approaches are urgently needed to assess the quality of water supplies. Because of their simplicity and sensitivity, bacterial tests play an important role in the detection and screening of genotoxins or cytotoxins in water. Thus, the bacterial Lux-Fluoro test, which is a combination of two bioassays that simultaneously measure the genotoxicity (SOS-Lux test) and the cytotoxicity (LAC-Fluoro test), was used to identify polluted water from samples of rural and urban sources, collected from 10 different locations in the Punjab rivers’ basin. We identified at least three samples from rural origin having a high cytotoxic potential. The highest toxicity was found for the sample obtained from a draining canal collecting runoff water from the fields. The two other highly contaminated samples identified were taken from two ponds of different villages. The water samples obtained from the Ravi river and from the water tap in a suburb of the megacity Lahore showed no sign of genotoxicity or cytotoxicity. Seven control samples with differing genotoxic and cytotoxic potency were shown for comparison.     

Crystallographic report: Chlorodiphenyltin(IV) piperidine‐1‐carbodithioate

A trigonal bipyramidal C₂ClS₂ coordination geometry for tin is found in Ph₂Sn(S₂CN(CH₂)₅)Cl. Copyright © 2005 John Wiley & Sons, Ltd.     

Crystallographic report: Chlorodimethyltin(IV) piperidine‐1‐carbodithioate

Me₂Sn(S₂CN(CH₂)₅)Cl contains five‐coordinated tin with a bidentate dithiocarbamate ligand spanning equatorial and axial positions in a distorted trigonal bipyramidal geometry. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis, Characterization, and Biological Activity of n-Tributyltin Derivatives of Pharmaceutically Active Carboxylates

Summary.  Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). ¹¹⁹Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin. Received September 20, 2001. Accepted (revised) December 6, 2001     

Polymeric emulsion and crosslink-mediated synthesis of super-stable nanoparticles as sustained-release anti-tuberculosis drug carriers

This study focused on evaluating four emulsion-based processing strategies for polymeric nanoparticle synthesis to explicate the mechanisms of nanoparticle formation and the influence on achieving sustained-release of two anti-tuberculosis drugs, isoniazid and rifampicin. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles were formulated with and without sorbitan mono-oleate as a stabilizer using emulsion-solvent-surfactant-evaporation (ESSE) and emulsion-solvent-evaporation (ESE) approaches. An alginate solution gelled by ionic crosslinking with calcium chloride was employed to prepare alginate hydrogel nanoparticles via reverse-emulsion-cationic-gelification (RECG) and reverse-emulsion-surfactant-cationic-gelification (RESCG) approaches. In vitro drug release analysis was performed. The size, zeta potential and morphology of the nanoparticles were analyzed. Molecular mechanics energy relationships (MMER) were employed to explore the spatial disposition of alginate and PLGA with respect to the emulsifying profile of sorbitan monooleate and to corroborate the experimental findings. Results revealed that particle size of the PLGA nanoparticles was influenced by the stabilizer concentration. Nanoparticles synthesized by the ESSE approach had smaller sizes of 240±8.7 nm and 195.5±5.4 nm for rifampicin- and isoniazid-loaded nanoparticles, respectively. This was a substantial size reduction from nanoparticles generated by the ESE approach (>1000 nm). The RESCG approach produced stable and higher nanoparticle yields with desirable size (277±1.0 nm; 289±1.2 nm), a low polydispersity index (27.1±0.3 mV; 28.5±0.5 mV) and drug entrapment efficiency of 73% and 75% for isoniazid and rifampicin, respectively. Drug release from the ESSE and RESCG synthesized nanoparticles displayed desirable release of the two anti-TB drugs with sustained zero-order kinetics over a period of 8h. MMER supported the mechanisms of nanoparticle formation with a sphericalized interlaced network configuration.     

The aftermath of the interplay between the endoplasmic reticulum stress response and redox signaling

The endoplasmic reticulum (ER) is an essential organelle of eukaryotic cells. Its main functions include protein synthesis, proper protein folding, protein modification, and the transportation of synthesized proteins. Any perturbations in ER function, such as increased demand for protein folding or the accumulation of unfolded or misfolded proteins in the ER lumen, lead to a stress response called the unfolded protein response (UPR). The primary aim of the UPR is to restore cellular homeostasis; however, it triggers apoptotic signaling during prolonged stress. The core mechanisms of the ER stress response, the failure to respond to cellular stress, and the final fate of the cell are not yet clear. Here, we discuss cellular fate during ER stress, cross talk between the ER and mitochondria and its significance, and conditions that can trigger ER stress response failure. We also describe how the redox environment affects the ER stress response, and vice versa, and the aftermath of the ER stress response, integrating a discussion on redox imbalance-induced ER stress response failure progressing to cell death and dynamic pathophysiological changes.Subject terms: Mechanisms of disease, Cell biology     

Highly oxygenated triterpenes from the roots of Atropa acuminata

Two new oleanane triterpenes; 2alpha,3alpha,24-trihydroxyolean-12-ene-28,30-dioic acid ([structure: see text]) and 2alpha,3alpha,24,28-tetrahydroxyolean-12-ene ([structure: see text]) have been isolated from the roots of Atropa acuminata. Anti-oxidant p-hydroxyphenethyl trans-ferulate ([structure: see text]), beta-sitosterol-3-O-beta-D-glucopyranoside ([structure: see text]) and oleanolic acid ([structure: see text]) have also been reported for the first time from this species. The structures were determined by spectroscopic studies including 2D-NMR.     

Decomposition of vegetables for determination of Zn,Cd, Pb and Cu by stripping voltammetry

A simple and accurate digestion method using nitric acid, perchloric acid and hydrogen peroxide has been developed for use in trace analysis for heavy metals in vegetables by differential pulse anodic stripping voltammetry. The recovery of the metals from the samples is lower if the hydrogen peroxide is omitted from the digestion mixture. Standard reference materials have been analysed satisfactorily by this method.