Five wild-growing Artemisia (Asteraceae) species from Serbia and Montenegro: Essential oil composition and its chemophenetic significance

In this work, we analyzed the essential oils (EOs) obtained by hydrodis-tillation from the aerial parts of five Artemisia species: A. alba Turra, A. pontica L., A. scoparia Waldst. & Kitam., A. vulgaris L., originated from Serbia and A. umbelliformis Lam. subsp. eriantha (Ten.) Vall?s-Xirau & Oliva Bra?as, originated from Montenegro by gas chromatography coupled with mass spectro-metry (GC/MS). In total, 91 compounds were detected, and 78 were identified. Even though a high number of compounds were detected, each sample had only 18 to 35, attesting to a great diversity of compounds within these taxa. Depending on the species and the locality (geographical origin), EO was dominated by either monoterpenes or sesquiterpenes, with artemisia ketone, 1,8-cineole (eucalyptol), fragranol, ?-thujone, ?-thujone, and myrcene being the dominant compounds. Obtained results were coupled with a extensive literature data and used in multi-variate chemometric approach to assess the chemophenetic significance of EO.

Identification of new process-related impurity in the key intermediate in the synthesis of TCV-116

Development of safe and effective drugs requires complete impurity evaluation and, therefore, knowledge about the formation and elimination of impurities is necessary. During impurity profiling of a key intermediate during synthesis of candesartan cilexetil (1-(((cyclohexyloxy)carbonyl) oxy)ethyl 1-((2’-(2H-tetrazol-5-yl)-[1,1’-biphenyl]-4-yl) methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate, TCV-116), a novel compound, which had not been reported previously, was observed. Structural elucidation of impurity was achieved by liquid chromatography hyphenated to different high resolution mass analyzers. Based on exact mass measurements and fragmentation pattern, a chloro alkyl carbonate ester analogue of the intermediate was identified. Structure of the impurity was confirmed by mass spectro-metric and NMR analyses of the target substance. Identified impurity could represent a hazard if it is transferred to the final API stage and its presence should be kept below allowed limits. Further investigation could reveal whether bis(1-chloroethyl) carbonate is a precursor to impurity formation. Therefore, synthesis should be regulated so as to minimize impurity production. Analysis of the final product indicated that the amount of impurity did not exceed 50 mg L−1, which represents the detection limit, determined according to the signal/noise ratio.

Effects of Implant Temperature on Disordering of AlAs-GaAs Superlattices

ABSTRACTThe effect of implant temperature, superlattice period, and directional diffusion has been studied for silicon impurity-enhanced compositional disordering of GaAs-AlAs superlattices (SL) of 9 ran and 16 nm period. The SL were implanted with Si at temperatures of 483 K, 293 K, and 77 K, with an energy of 100 keV and dose of 2.5 × 1014 cm-2. These were examined by cross-sectional transmission electron microscopy and secondary ion mass spectro-scopy for structural and compositional information. The damage due to implantation prior to annealing is strikingly less for superlattices than for bulk GaAs. All annealed samples exhibited disordering, with the 9 nm period SL exhibiting a deeper disordered region than the 16 nm SL. The greatest enhancement was found in the 9 nm period SL implanted at 77 K, in which the disordering extended from a depth of 25 nm to =300 nm. The mixing was found to be anisotropie, with the SL mixing propagating greater in depth than in the lateral directions. The result has important implications for high resolution patterning possibilities with this method.