Rapid methods for radiostrontium determination in aerosol filters and vegetation in emergency situations using PS resin

Journal of Radioanalytical and Nuclear Chemistry - This study describes a rapid and novelty method for radiostrontium determination in aerosol filters and vegetation based on the use of plastic...     

Automated separation of 99Tc using plastic scintillation resin PSresin and openview automated modular separation system (OPENVIEW-AMSS)

Automated methods for the analysis of radionuclides potentially increase laboratory productivity by reducing operator intervention and increasing the number of samples that can be treated in a given time. To this end, here we report a new openview automated modular separation system which can be used in combination with PSresin, in this case, for the analysis of ⁹⁹Tc. Quality parameters of this method using the automated system were comparable to those obtained manually and quantification of water samples spiked with low levels of ⁹⁹Tc resulted in deviations lower than 10% for all the samples analysed.

     

Correction to: Evaluation of background radiation level and excess lifetime cancer risk in Doon valley,Garhwal Himalaya

Journal of Radioanalytical and Nuclear Chemistry -     

Strategic Substitution of −OH/−NR2 (R=Et,Me) Imparts Colorimetric Switching between F− and Hg2+ by Salicyaldehyde/Benzaldehyde-Quinoxaline Conjugates

We herein report two salicyaldehyde-quinoxaline ( HQS and HQSN ) conjugates and a benzaldehyde-quinoxaline ( QBN ) conjugate to fabricate selective chemosensors for F⁻ and Hg²⁺ in the micromolar range. This work demonstrates how sensing outcomes are affected by modulating proton acidity by introducing an electron donating group, −NEt₂, in the probe backbone. Interestingly, the un-substituted probe HQS can selectively detect F⁻, whereas HQSN and QBN are selective for Hg²⁺. In order to gain insights into the mechanism of sensing, geometry optimizations have been carried out on QS⁽⁻¹⁾ , QS⁽⁻¹⁾⋅⋅⋅HF , QSN⁽⁻¹⁾ and QSN⁽⁻¹⁾⋅⋅⋅HF and the experimental data are validated in terms of free energy and pK_a values. Detailed DFT and TD-DFT analyses provide ample support towards the mechanism of sensing of the analytes.     

Buffer Influence on the Amino Acid Silica Interaction

Protein-surface interactions are exploited in various processes in life sciences and biotechnology. Many of such processes are performed in presence of a buffer system, which is generally believed to have an influence on the protein-surface interaction but is rarely investigated systematically. Combining experimental and theoretical methodologies, we herein demonstrate the strong influence of the buffer type on protein-surface interactions. Using state of the art chromatographic experiments, we measure the interaction between individual amino acids and silica, as a reference to understand protein-surface interactions. Among all the 20 proteinogenic amino acids studied, we found that arginine (R) and lysine (K) bind most strongly to silica, a finding validated by free energy calculations. We further measured the binding of R and K at different pH in presence of two different buffers, MOPS (3-(N-morpholino)propanesulfonic acid) and TRIS (tris(hydroxymethyl)aminomethane), and find dramatically different behavior. In presence of TRIS, the binding affinity of R/K increases with pH, whereas we observe an opposite trend for MOPS. These results can be understood using a multiscale modelling framework combining molecular dynamics simulation and Langmuir adsorption model. The modelling approach helps to optimize buffer conditions in various fields like biosensors, drug delivery or bio separation engineering prior to the experiment.     

New pyrazolyl-dibenzo[b,e][1,4]diazepinones: room temperature one-pot synthesis and biological evaluation

Molecular Diversity - Several new (5-aryloxy-pyrazolyl)- and (5-aryl/olefin-sulfanyl-pyrazolyl)-dibenzo[b,e] [1,4] diazepinone scaffolds have been synthesized, by assembling 5-substituted...     

Homoleptic Ti[ONO]2 type complexes of amino-acid-tethered phenolato Schiff-base ligands: Synthesis,characterization, time-resolved fluorescence spectroscopy,and cytotoxicity against ovarian and colon cancer cells

Six homoleptic Ti (IV) compounds of dianionic tridentate ONO Schiff base ligands with various substitutions were prepared from chiral amino acids, 2-hydroxybenzaldehyde, which were generated in situ, and Ti (OⁱPr)₄. The compounds were spectroscopically characterized and the molecular geometries of five complexes were established by X-ray crystallography; for two structures, two independent molecules compose the asymmetric units. The di-anionic, tridentate ligands coordinate the titanium centers via the carboxylate-O-, imine-N- and phenoxide-O atoms to form five- and six-membered chelate rings. The molecules are based on a trans-N₂O₄ donor with each carboxylate-O atom trans to a phenoxide-O atom. For the smallest derivative with Me substitution, racemization occurs during repeated recrystallization. Photophysical profiles of the titanium compounds in the solid phase and in solution are discussed. Marked cytotoxicities were recorded toward human ovarian A2780 and colon HT-29 cancer cells with IC₅₀ values ranging between 23 ± 2 and 103 ± 3 μM. Comparative hydrolytic stability of the complexes were studied by NMR in 10% D₂O solutions which provided t_1/2 values of up to 15 ± 2 hr.     

Synthesis of furan-fused 1,4-dihydrocarbazoles via an unusual Garratt-Braverman Cyclization of indolyl propargyl ethers and their antifungal activity

The reactivity of indole based bis-propargyl ethers 4a-4g under Garratt-Braverman condition (KOBu^t in refluxing toluene) has been studied. Interestingly, these propargyl systems with one arm attached with substituted 3-indolyl derivatives leaving the other arm unsubstituted produced the 3,4-furan fused dihydrocarbazole derivatives 6a-6g (and not the expected carbazole derivatives) as the predominant product (70–82%) making this methodology to access such derivatives an attractive route. The results are supported by computational studies and some of the carbazole derivatives showed good antifungal activities.