Expanding the structural repertoire of β/α Ant-Pro (anthranilic acid-proline) oligomers into γ/α 2-Amb-Pro (2-aminomethyl benzoic acid-proline) oligomers

In this article, we report a novel class of heterogeneous synthetic oligomers featuring the conformationally constrained amino acid residues – 2-aminomethyl benzoic acid (2-Amb) and proline (Pro) in repeating sequences. Oligomers as large as hexadecamers featuring the conformationally restricted γ/α 2-Amb-Pro motif have been assembled using solution-phase Boc strategy, following multi-step synthetic sequences starting from the commercially available O-toluic acid. EDC-mediated peptide coupling has been found to be optimum for the assembly of the relatively non-polar oligomers, which could be readily purified by the standard column chromatographic purification procedures. This study offers considerable prospects of expanding the structural repertoire of β/α Ant-Pro motif, which has been described earlier to assume right-handed helical architecture displaying robust nine-membered-ring closed network of hydrogen-bonding interactions, into γ/α 2-Amb-Pro motif.     

Incurred sample reanalysis of cefuroxime in rabbit ocular tissues—A case study

In this paper, we present the incurred sample reanalysis (ISR) data for cefuroxime in various ocular tissues of rabbits. Based on the cefuroxime concentration vs. time profile in various ocular tissues, three chosen time points enabled ISR assessment. Cefuroxime was quantitated in the ocular tissues using a published liquid chromatography–electrospray ionization/tandem mass spectrometry method operated under the multiple reaction-monitoring mode in positive ion mode. Regardless of the ocular tissue, the linearity range was 12.7–2760 ng/ml with a correlation coefficient (r²) of ≥0.996. All of the ISR samples representing various ocular tissues met the acceptance criteria. To the best of our knowledge, this is the first report showing the ISR of ocular tissues in any species.     

Synthesis and mesomorphic evaluation of new calamitic liquid crystals containing benzothiazole core

The design and synthesis of new calamitic benzothiazole-based liquid crystals,2-[4-（4-alkyloxybenzoyloxy）-phenyl]ben-zothiazoles are presented.The target compound was characterized using spectroscopic techniques,such as FT-IR,NMR(¹H and ¹³C),microanalysis and EI-MS.The liquid crystalline behaviours of these compounds were thoroughly examined by differential scanning calorimetry and polarizing optical microscope techniques.These materials exhibited enantiotropic nematic phase with high thermal stability（>168℃）.Smectic A phase starts to emerge as monotropic（metastable） phase from C10 member and changes into enantiotropic（stable） phase from C12 and persists up to C16 members.     

Using LES to Study Reacting Flows and Instabilities in Annular Combustion Chambers

Great prominence is put on the design of aeronautical gas turbines due to increasingly stringent regulations and the need to tackle rising fuel prices. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. In the particular field of annular combustion chambers, these instabilities often take the form of azimuthal modes. To predict these modes, one must compute the full combustion chamber, which remained out of reach until very recently and the development of massively parallel computers. Since one of the most limiting factors in performing Large Eddy Simulation (LES) of real combustors is estimating the adequate grid, the effects of mesh resolution are investigated by computing full annular LES of a realistic helicopter combustion chamber on three grids, respectively made of 38, 93 and 336 million elements. Results are compared in terms of mean and fluctuating fields. LES captures self-established azimuthal modes. The presence and structure of the modes is discussed. This study therefore highlights the potential of LES for studying combustion instabilities in annular gas turbine combustors.