Resolution of enantiomers of [α-hydroxy-(o-chlorophenyl)methyl]phosphinic acid via diastereomeric salt formation with enantiopure 1-phenylethylamines

The resolution of racemic α-hydroxy-H-phosphinic acid with enantiopure 1-phenylethylamines via diastereomeric salt formation was investigated. X-Ray crystallographic analysis of the salt revealed that (R)-1-phenylethylamine to be efficient resolving agent for obtaining a single enantiomer of [α-hydroxy-(o-chlorophenyl)methyl]phosphinic acid. Resolving racemic α-hydroxy-H-phosphinic acid with (S)-2-phenylethylamine also gave access to (S)-α-hydroxyalkylphosphinic acid in good yield.     

A skin-contact-actuated micropump for transdermal drug delivery

In this paper, a skin-contact-actuated dispenser/micropump for transdermal drug delivery applications is presented. The micropump consists of stacked polydimethylsiloxane layers mounted on a silicon substrate and operates based on the evaporation and condensation of a low-boiling-point liquid. Therefore, there is no need for a heater and a power source, since only the thermal energy provided by skin contact is required for the actuation. A prototype device with overall dimensions of 14 mm × 14 mm × 8 mm is fabricated and characterized. For a perfluoro compound working fluid (3M FC-3284), a flow rate of 28.8 μ L/min and a maximum back pressure of 28.9 kPa is measured.     

The effect of melt flow index, melt flow rate, and particle size on the thermal degradation of commercial high density polyethylene powder

The powder of EX5 grade of high density polyethylene—without any additives—manufactured by Amirkabir petrochemical company was separated by shaker equipment. The separated powder of average diameter ~25, ~62.5, ~87.5, ~112.5, ~137.5, ~175 and the particles >200 μm was tested by a thermogravimetric (TG) analysis instrument in nitrogen atmosphere and heating rates of 10, 20, and 30 °C min^?1. In addition, the separated powders were analyzed by a melt flow index (MFI) instrument, and the viscosity average molecular mass (M _v) of the powders was tested by a viscometer. Kinetic evaluations were performed by Friedman and Kissinger analysis methods and apparent activation energy for the overall degradation of the powders was determined. The effects of molecular mass, MFI, MFR, and particle size on the degradation TG curve, derivative thermogravimetry curve breadth, and activation energy of thermal degradation were considered. The results showed that the M _v of EX5 pipe grade produced by two serial reactors is increased by increasing of the particle size and, MFI is decreased with a little deviation by particle size increasing. The particle size has no obvious effect on the melt flow rate (MFR), and MFR as function of molecular mass distribution does not change very much. The results showed that the powder with bigger particles and higher molecular mass moderately increases the activation energy and shifts the degradation curve to the higher temperatures.     

Quantification of Competing H3PO4 Versus HPO3 + H2O Neutral Losses from Regioselective 18O-Labeled Phosphopeptides

Abundant neutral losses of 98 Da are often observed upon ion trap CID-MS/MS of protonated phosphopeptide ions. Two competing fragmentation pathways are involved in this process, namely, the direct loss of H₃PO₄ from the phosphorylated residue and the combined losses of HPO₃ and H₂O from the phosphorylation site and from an additional site within the peptide, respectively. These competing pathways produce product ions with different structures but the same m/z values, potentially limiting the utility of CID-MS³ for phosphorylation site localization. To quantify the relative contributions of these pathways and to determine the conditions under which each pathway predominates, we have examined the ion trap CID-MS/MS fragmentation of a series of regioselective ¹⁸O-phosphate ester labeled phosphopeptides prepared using novel solution-phase amino acid synthesis and solid-phase peptide synthesis methodologies. By comparing the intensity of the –100 Da (–H₃PO₃ ¹⁸O) versus –98 Da (–[HPO₃ + H₂O]) neutral loss product ions formed upon MS/MS, quantification of the two pathways was achieved. Factors that affect the extent of formation of the competing neutral losses were investigated, with the combined loss pathway predominantly occurring under conditions of limited proton mobility, and with increased combined losses observed for phosphothreonine compared with phosphoserine-containing peptides. The combined loss pathway was found to be less dominant under ion activation conditions associated with HCD-MS/MS. Finally, the contribution of carboxylic acid functional groups and backbone amide bonds to the water loss in the combined loss fragmentation pathway was determined via methyl esterification and by examination of a phosphopeptide lacking side-chain hydroxyl groups.

High-performance supercapacitors based on an ionic liquid-derived nanofibrillated mesoporous carbon

This article reports the superior specific capacitance, energy, and power density of a nanofibrillated mesoporous carbon derived from an ionic liquid source (IFMC). It was concluded that high specific capacitance and good electrical conductivity were originated from contribution of nitrogen content of IFMC, also the interesting nanofibrillated structure. A specific capacitance of 235 F g^?1 at a high discharge current of 5 A g^?1 was estimated for IFMC-based electrode which is higher than the most reported capacitance for carbon materials. An excellent performance of the nanofibrillated mesoporous carbon along with proper concentration of nitrogen constituent in the carbonaceous framework is indicative for important effects of tuning the carbon nanostructure for energy storage applications.     

Host mobility key management in dynamic secure group communication

The key management has a fundamental role in securing group communications taking place over vast and unprotected networks. It is concerned with the distribution and update of the keying materials whenever any changes occur in the group membership. Wireless mobile environments enable members to move freely within the networks, which causes more difficulty to design efficient and scalable key management protocols. This is partly because both member location dynamic and group membership dynamic must be managed concurrently, which may lead to significant rekeying overhead. This paper presents a hierarchical group key management scheme taking the mobility of members into consideration intended for wireless mobile environments. The proposed scheme supports the mobility of members across wireless mobile environments while remaining in the group session with minimum rekeying transmission overhead. Furthermore, the proposed scheme alleviates 1-affect-n phenomenon, single point of failure, and signaling load caused by moving members at the core network. Simulation results shows that the scheme surpasses other existing efforts in terms of communication overhead and affected members. The security requirements studies also show the backward and forward secrecy is preserved in the proposed scheme even though the members move between areas.