Local Dynamic Buckling of C-Shape Profile Subjected to Bending

This paper deals with local dynamic buckling of thin-walled girder segments (short beam-columns) subjected to bending. Various shapes of pulse loading (triangle, trapezoid and rectangle) with a duration corresponding to the fundamental period of vibration were taken into account. Assumed boundary conditions correspond to a simple support, this agrees with conditions that exist in the place of the diaphragm in a long spar. The problem was solved by finite element method. In order to determine the critical load pulse amplitudes Volmir, Budiansky-Hutchinson, Ari-Gur and Simonetta criteria were employed

Flurbiprofen: A Study of the Behavior of the Scalemate by Chromatography, Sublimation, and NMR

2-(2-Fluoro-4-biphenyl) propionic acid (flurbiprofen), from the phenylalkanoic acid family of nonsteroidal anti-inflammatory drugs (NSAID’s), is currently on the pharmaceutical market as a racemate. This racemic compound was tested for its propensity to undergo the self-disproportionation of enantiomers (SDE) phenomenon by various forms of chromatography (SDEvC), such as routine gravity-driven column chromatography, medium-pressure liquid chromatography (MPLC), preparative thin-layer chromatography (PTLC), and size-exclusion chromatography (SEC), as well as by sublimation (SDEvS). Furthermore, examination by nuclear magnetic resonance (NMR) in various solvents found that flurbiprofen exhibited the phenomenon of self-induced diastereomeric anisochronism (SIDA). By measurement of the diffusion coefficient (D), the longitudinal relaxation time (T1), and the transverse relaxation time (T2) using NMR, as well as by electrospray ionization-mass spectrometry (ESI-MS) examinations, the preferred intermolecular association was found to be solvent dependent, e.g., heterochiral association was preferred in toluene, while homochiral association was preferred in more polar solvents. This study also attempted, unsuccessfully, to correlate the NMR measurements of flurbiprofen with chromatographic outcomes for the rationalization and prediction of chromatographic results based on NMR measurements. Because the intermolecular hydrogen bonding of the acid groups in flurbiprofen overwhelmingly predominates over other intermolecular interactions, flurbiprofen seemed to represent a good test case for this idea. The behavior of scalemic samples of flurbiprofen is important, as, although it is currently dispensed as a racemate, clinical applications of the R enantiomer have been investigated. SDEvC and SDEvS both have ramifications for the preparation, handling, and storage of enantioenriched flurbiprofen, and this concern applies to other chiral drugs as well.The authors gratefully acknowledge financial support from the Ministry of Science and Higher Education, Poland (grant no. 668, A.W.; grant no. 659, M.K.; and SMGR.RN.20.264, A.K.) and IKERBASQUE, the Basque Foundation for Science, Spain (V.A.S.)

Synthesis of Resorcinarene Derivatives via the Catalyzed Mannich Reaction, Part 3: Glycol Derivatives of Resorcinarene

Urbaniak M, Mattay J, Iwanek W. Synthesis of Resorcinarene Derivatives via the Catalyzed Mannich Reaction, Part 3: Glycol Derivatives of Resorcinarene. Synthetic Communications. 2011;41(5):670-676.[image omitted] A series of resorcinarene glycol derivatives have been synthesized as secondary substitution products via a Mannich reaction catalyzed by iminodiacetic acid. The products are potentially useful candidates as podands for supramolecular chemistry. The synthesis presented in this article is effective and uses readily available and inexpensive substrates

Synthesis of Resorcinarene Derivatives by the Catalyzed Mannich Reaction, Part 2: Resorcinarene Derivatives with Unsaturated Bonds

Urbaniak M, Mattay J, Iwanek W. Synthesis of Resorcinarene Derivatives by the Catalyzed Mannich Reaction, Part 2: Resorcinarene Derivatives with Unsaturated Bonds. Synthetic Communications. 2008;38(24):4345-4351.The conditions of a simple synthesis of alkenyloxymethyl and the alkynyloxymethyl derivatives of resorcinarene by the Mannich reaction catalyzed with iminodiacetic acid are described. The synthesis presented in this article is effective and uses readily available and inexpensive substrates