Properties of large scale plasma flow during the early stage of the plasmaspheric refilling

The objective is to better characterize the macroscopic properties of the interhemisphere plasma flow by solving a more complete set of hydrodynamic equations than that solved previously. Specifically, the ion continuity, momentum and energy equations were solved for the plasma flow along the closed magnetic field lines. During the initial stage of the supersonic outflow in the equatorial region, the ions cool substantially. Using the hydrodynamic model for the large-scale plasma flow, the dynamics of shocks was examined which form in the geomagnetic flux tubes during the early stages of refilling. These shocks are more like those forming in neutral gases than the electrostatic shocks driven by microinstabilities involving ion-ion interaction. Therefore, the shocks seen in the hydrodynamic model are termed as hydrodynamic shocks. Such shocks are generally unsteady and therefore the usual shock jump conditions given by Rankine-Hugoniot relations are not strictly applicable to them. The density, flow velocity and temperature structures associated with the shocks are examined for both asymmetrical and symmetrical flows. In the asymmetrical flow the outflow from one of two conjugate ionospheres is dominant. On the other hand, in the symmetrical case outflows from the two ionospheric sources are identical. Both cases are treated by a two-stream model. In the late type of flow, the early-time refilling shows a relaxation type of oscillation, which is driven by the large-scale interactions between the two identical streams. After this early stage, the resulting temperature structure shows some interesting features. In the equatorial region the streams are isothermal, but in the off-equatorial regions the streams have quite different temperatures, and also densities and flow velocities. The dense and slow stream is found to be warmer than the low-density fast stream. In the late stage of refilling, the temperature is found to steadily increase from the conjugate ionospheres towards the equator; the equatorial temperature is found to be as high as about 8000 K compared to the ionospheric temperature of 3600 K

ChemInform Abstract: Synthesis of Urea Tethered Glycosylated Amino Acids and Glycopeptides Mediated by DPPA Employing Nα‐Fmoc‐Asp/Glu‐5‐oxazolidinones

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

A facile synthesis of N-Z/Boc-protected 1,3,4-oxadiazole-based peptidomimetics employing peptidyl thiosemicarbazides

Synthesis of 1,3,4-oxadiazole containing peptidomimetics is described by a p-TsCl/pyridine-mediated cyclization of the corresponding dipeptidyl thiosemicarbazides, which are readily prepared by coupling N-protected amino acid hydrazides with amino acid-derived isothiocyanato esters. Further, the protocol has also been extended for the synthesis of orthogonally protected 1,3,4-oxadiazole tethered mimetics as well. The synthetic route is simple and mild conditions are used so that the chirality of the starting amino acids is retained. © 2010 Elsevier Ltd. All rights reserved

Ultrasound accelerated conversion of Nα-urethane protected peptide esters to their thiopeptides using P2S5

A fast and efficient synthesis of Nα-protected thiopeptide esters from the corresponding peptide esters using P2S5 as thionating agent assisted by ultrasonication has been described. The conversion of peptide bond into thioamide was complete in 20-40 min at rt. The reaction was accomplished without using any base. The products isolated were characterized using 1H NMR, 13C NMR and mass spectroscopy. © 2008 Elsevier B.V. All rights reserved

Strategies to Enhance E-Commerce in Rural Areas

Recent economic statistics and future projections by experts indicate that opportunities for economic growth in the future is going to come mainly from businesses of the ìnew economyî that utilize the powerful strategy of e-commerce. The recommendations in this article emanate from extensive primary research in the rural parts of North East USA with special focus on the rural parts of Pennsylvania. The primary research is combined with secondary research of the status of e-commerce in rural parts of several other countries thereby rendering the recommendations generically applicable

ChemInform Abstract: A Facile Synthesis of N‐Z/Boc‐Protected 1,3,4‐Oxadiazole‐Based Peptidomimetics Employing Peptidyl Thiosemicarbazides.

A convenient protocol is presented for the cyclization of dipeptidyl thiosemicarbazides (III)

ChemInform Abstract: Synthesis of Boc‐Amino Tetrazoles Derived from α‐Amino Acids

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

A convenient synthesis of 1,3,4-thiadiazole and 1,3,4-oxadiazole based peptidomimetics employing diacylhydrazines derived from amino acids

Synthesis of novel orthogonally protected 1,3,4-thiadiazole and 1,3,4-oxadiazole tethered dipeptide mimetics is described. Both the heterocycles are prepared via a set of diacylhydrazines derived from amino acids. 1,3,4-Thiadiazoles are synthesized by dehydrosulfurization using Lawesson's reagent while 1,3,4-oxadiazoles are obtained by EDC mediated cyclodehydration. © 2010 Elsevier Ltd. All rights reserved