New methodology for uranium analysis in swipe samples for nuclear safeguards purposes

Environmental swipe sampling for safeguards purpose has been used by International Atomic Energy Agency since 1997, being a powerful tool to detect undeclared materials and activities. This work describes a new methodology for swipe samples analysis based on ultrasound-assisted acid leaching and compares it with traditional total digestion bulk analysis. The proposed method requires few preparation steps, decreasing the risk of contamination, reduced amounts of reagents and a good option to extract uranium from swipe sample. In a real case study, the swipe samples were collected in a conversion plant at IPEN/CNEN, Brazil. The measurements were carried out by ICP-MS and the results showed relative error lower than 0.96 % for uranium isotopic ratios for the certified reference material (NBS U200). The uncertainties were estimated by following the ISO GUM, with a confidence level of 95 %. The uncertainties percentage for n(²³⁵U)/n(²³⁸U) ratio of the samples ranged from 2.5 to 4.3 %. The values of uranium isotopic ratio obtained for each method demonstrate the viability of using the methodology proposed in this work.     

A spectrophotometric study of the charge transfer complexes of [60]fullerene with different tert-butylcalix[4]crowns

Formation of the charge-transfer complexes between various calix[4]crowns (1-4) and [60]fullerene were studied in toluene solution using UV-vis spectrophotometry. The stability constants and the thermodynamic data of the resulting 1:1 complexes were determined and were found to decrease with increasing the size of the crown moiety of the calixcrown. Except the complex of 3, all the complexes were found to be enthalpy stabilized but disfavored in terms of entropy.     

Anti-inflammatory, laxative and intestinal motility effects of Senna macranthera leaves

Several species of Senna are well known for their therapeutic properties, being used in folk medicine to treat throat inflammation and constipation. In this regard, the anti-inflammatory, laxative and intestinal motility effects of different extracts of Senna macranthera (Colladon) H. Irwin and Barneby leaves were determined. The hexane extract significantly reduced carrageenan-induced paw oedema in rats in a manner similar to that of sodium diclofenac. A laxative effect was observed for the methanolic and hexane extracts comparative to the standard drug bisacodyl; however, only the hexane extract increased the intestinal motility in the studied period. Moreover, the extracts were evaluated for their antioxidant activity and the ethyl acetate extract presented a pronounced activity comparable to the standard rutin. Phytochemical screening was also performed and phenolic compounds like flavonoids, tannins and coumarins were observed in all extracts except for the hexane extract, which instead presented anthrones, triterpenes and steroids in its composition. The HPLC profile showed the presence of the anthraquinone emodine in all tested extracts.     

Synthesis and properties of conformationally rigid cyclouridylic acid having a covalent bonding linker between the uracil 5-position and the 5′-phosphate group

A novel cyclouridylic acid 1 having a propylene bridge between the uracil 5 position and the 5′-phosphate group was synthesized. The structure of 1 was analyzed by ¹H NMR, and CD spectroscopy, which suggested that the cyclonucleotide 1 was highly stabilized in a considerably rigid g⁺/C3′-endo conformation with the base orientation of anti. The molecular mechanics calculation of 1 gave a similar conclusion.     

Preparation of Dry Extract of<em> Mikania glomerata</em> Sprengel (Guaco) and Determination of Its Coumarin Levels by Spectrophotometry and HPLC-UV

Guaco (Mikania glomerata Sprengel) syrup is one of the most popular herbal medicines used to treat the symptoms of asthmatic bronchitis, cough and hoarseness. The coumarin 2H-1-benzopyran-2-one, is one of the major constituents of Guaco and contributes to its pharmacological effects. The pharmaceutical capsule form of dry extract of Guaco is recommended by the Brazilian Program of Medicinal Plants and Herbal Medicines and used in primary health care. In order to identify a new protocol to obtain the raw material for Guaco capsule production we evaluated two methods, including a freeze-drying process (lyophilization) and the spray-dryer technique, as well as the use of two adjuvants, Maltodextrins and Aerosil^?, in different concentrations. The coumarin levels of the dried extracts were analyzed by UV-spectrophotometry and HPLC-UV/DAD. The adjuvant Aerosil^? 8% showed better dry powder physical appearance. Lyophilization was observed to be the best process to obtain the dry extract of Guaco based on the measured coumarin levels.