Separation of rare earth,nuclear-fuel burn-up monitors in the 10−9 mole range by high-pressure liquid chromatography with UV-detection

Anion-exchange chromatography of the rare earth (Sm, Nd, Pr, Ce) ions in methanol-nitric acid-water media is performed using high-pressure liquid chromatography. The separation method is especially designed for determination of¹⁴⁸Nd in the nuclear fuel cycle in order to find precise burn-up values. The high-pressure liquid chromatography method presented here is very fast, gives high resolutions, and enables collection of selected fractions containing nmoles of rare earth by UV monitoring at 280 nm of the eluate.     

Studies of critical factors in the determination of arsenic in Standard Reference Materials of Marine origin by ETAAS: ;NMKL * interlaboratory study

A study to determine factors which are known to influence the electrothermal atomic absorption (ETAAS) determination of As has been performed. The study has been carried out using five sample solutions of marine Standard Reference Materials distributed to four participating laboratories. Uncoated and pyrolytically coated graphite tubes with Lvov platform and Ni and Pd/Mg as chemical modifiers have been tested. No differences in results have been obtained between AAS instruments equipped with Zeeman correction or deuterium arc background correction. Small differences in concentration levels of arsenic as well as in characteristic mass were found when chemical modifiers were compared. Pd/Mg will be recommended in order to avoid a contamination of the graphite furnace with nickel. The characteristic mass was improved by using pyrolytically coated graphite tubes with the Lvov platform compared with uncoated graphite tubes with the Lvov platform. In the interlaboratory study, the standard addition procedure will be recommended.     

Self-assembling microparticles with controllable disruption properties based on cyclodextrin interactions

In this paper, we present the formation of particles by self-assembly of cyclodextrin polymers and hydrophobically modified dextran followed by a controlled disruption of the particles by addition of a trigger molecule competing for the cyclodextrin cavities. The produced particles are formed from poly(vinylpyrrolidone)-co-β-cyclodextrin and dextran-benzoate, both biocompatible polymers, and are all in the nano-/micrometer range and hence suitable for drug delivery purposes. The particle formation was studied in different ratios of poly(vinylpyrrolidone)-co-β-cyclodextrin and dextran-benzoate by visual inspections, dynamic light scattering, isothermal titration calorimetry and SEM. The triggering of particle disruption was achieved by addition of hydroxyadamantane which has a very strong affinity towards the β-cyclodextrin cavities. The stepwise addition of hydroxyadamantane was followed by dynamic light scattering and SEM measurements, revealing a disruption of the particles due to the addition of this competitor. These particles are believed to be promising candidates for controlled drug delivery systems, due to their unique ability to disrupt in a controlled manner.     

Garlicnin A from the fraction regulating macrophage activation of Allium sativum

Garlicnin A (1), a new stable, sulfur-containing compound isolated from a fraction of the acetone extracts of Allium sativum L. garlic bulbs, showed the potential to suppress tumor cell proliferation by inhibiting the polarization of M2 alternatively activated macrophages, and its structure was characterized as 3,4-dimethyl-5-(4,5-dithia-1E,7-octadiene)-tetrahydrothiophene-2-sulfoxide-S-oxide, on the basis of the results of spectroscopic analysis results.     

Synthesis of new indole derivatives structurally related to donepezil and their biological evaluation as acetylcholinesterase inhibitors

New series of indole derivatives analogous to donepezil, a well known anti-Alzheimer and acetylcholinesterase inhibitor drug, was synthesized. A full chemical characterization of the new compounds is provided. Biological evaluation of the new compounds as acetylcholinesterase inhibitors was performed. Most of the compounds were found to have potent acetylcholinesterase inhibitor activity compared to donepezil as standard. The compound 1-(2-(4-(2-fluorobenzyl) piperazin-1-yl)acetyl)indoline-2,3-dione (IIId) was found to be the most potent.     

Phyto-phospholipid complex of catechin in value added herbal drug delivery

Catechin (an anti-inflammatory, antioxidant, antitumour, and hepatoprotective bioflavonoid) is poorly absorbed across the GIT because it has multiple ring molecules that are too large to be absorbed by simple diffusion. It typically has poor miscibility with oils and other lipids which limit their ability to pass across the lipid rich outer membranes of enterocytes of small intestine. Thus catechin–phospholipid complex were prepared to improve its absorption by imparting an environment of improved lipophilicity. The phospholipid complexes of catechin were prepared with phosphatidylcholine in presence of dichloromethane by conventional solvent evaporation technique. Pharmacosomes thus prepared were evaluated for solubility, drug content, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X ray powder diffraction (XRPD), in vitro dissolution study and in vitro antioxidant activity. Prepared phospholipid complex showed high drug content (99.40%. w/w) and improved lipid solubility (0.79–1.97?mg/mL). FTIR, NMR, DSC and XRPD data confirmed the formation of phospholipid complex. Unlike the free catechin, catechin complex showed a sustained release over the 24?h of study. Catechin-phospholipid complex showed slightly better antioxidant activity than that of catechin at all dose levels. Thus it can be concluded that the phospholipid complex of catechin may be of potential use for improving absorption of catechin across the lipidic biological barriers in gastrointestinal tract. It was concluded that the complexation with phospholipids did not interfere with the biological activities. This herbal drug delivery system can pave the way for large molecules to pass through the lipophilic biological membrane (by the virtue of their amphiphilic nature) and get absorbed into the systemic circulation.     

Some applications of the Hales-Jewett theorem to field arithmetic

Let K be a field whose absolute Galois group is finitely generated. If K neither finite nor of characteristic 2, then every hyperelliptic curve over K with all of its Weierstrass points defined over K has infinitely many K-points. If, in addition, K is not an algebraic extension of a finite field, then every elliptic curve over K with all of its 2-torsion rational has infinite rank over K. These and similar results are deduced from the Hales-Jewett theorem.     

Resistance maximum across the spin glass to Kondo transition

In a recent theory of the noise model of alloys like AuFe a singular point at zero temperature was found to separate a spin glass phase at high concentrations and a Kondo phase at low concentrations. Despite this there is a resistance maximum in both “phases”, although of different characters. In the present letter a relation is given between the temperature of the maximum, T_m, the noise temperature, Δ_c, and the Kondo temperature, T_K. This extends a previously given expression, that is only valid in the spin glass limit Δ_c >> T_K, across the transition at Δ_c = T_K into the Kondo phase and values of Δ_c less than T_K.     

Spectroscopic study of oscillator strength and radiative decay time of colloidal CdSe quantum dots

Characterization of samples of cadmium selenide quantum dots (CdSe) QDs dissolved in toluene colloidal solutions at a concentration of 1.4 mg/ml was carried out through UV–Vis absorption and photoluminescence (PL) spectroscopy. The size-dependent absorption and red-shifted PL emission peak wavelengths could be tuned between 510–576 and 545–606 nm respectively. Optical absorption spectral measurements yielded CdSe QDs having diameters about ~ 2.44–3.69 nm with energy gaps 2.32–2.08 eV which are higher than the bulk CdSe (1.74 eV) reminiscent of quantum confinement. This is found to be in good agreement with the semi-empirical pseudopotential model. In addition, the first excitonic absorption transition 1S_(e)1S_3/2(h) oscillator strength and the corresponding fluorescence radiative decay time of CdSe QDs are assessed using relevant Einstein relations for absorption and emission in a two-level system. The elaborated calculations would anticipate that the transition oscillator scale with the CdSe QD radius as ~ R^2.54. Correspondingly, the calculated radiative decay times decrease from 56.4 to 23.2 ns which scale with CdSe QDs radius as ~ R^?2.155 in fairly good agreement with experimental values reported in the literature.