Fluorophore-appended steroidal saponin (dioscin and polyphyllin D) derivatives

The synthesis of three fluorophore-appended derivatives of dioscin and polyphyllin D is reported herein. Starting from trillin, dansyl derivatives A-C were prepared in overall yields of 7-12% over 7-10 steps. A study of their behavior in a variety of polar solvents suggests that dansyl derivatives A-C are capable of micellar self-assembly and can maintain cytotoxicities (IC50 = 15-18 muM) against the HeLa carcinoma cell line evaluated by standard MTT assay. [structure: see text]     

Electronic and chemical properties of nanostructured cerium dioxide doped with praseodymium

Nanostructured doped ceria is a prospective material for catalytic applications such as the construction of membranes with mixed electronic and ionic conductivity for effective syngas production. In this article, the surface properties of nanostructured ceria doped with praseodymium have been studied by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and Fourier transform infrared spectroscopy of adsorbed carbon monoxide. The effects of supporting 1.4 wt % Pt as well as structural changes upon the reduction of the samples with methane have been investigated. While in samples without supported platinum, mainly praseodymium cations are reduced in a methane atmosphere; stronger reduction of cerium cations was found in the case of surface modification with Pt. The structural differences correlate with results from temperature-programmed reaction experiments with methane. Explanations are discussed in terms of different reaction mechanisms.     

Microwave Accelerated Synthesis of N‐Phenylmaleimide in a Single Step and Polymerization in Bulk

Summary: This paper reports the microwave mediated direct synthesis of N‐phenylmaleimide ( 3 ) from maleic anhydride ( 1 ) and aniline ( 2 ) by using microwave irradiation. Good yields and very short reaction times were the main aspects of the method. The reaction conditions and kinetics of this process were investigated. Microwave irradiation in a boiling solvent showed the existence of a significant specific microwave effect. The microwave homopolymerization of 3 in bulk using 2,2′‐azoisobutyronitrile (AIBN) as a free radical initiator was also carried out.

Kinetic curves for the synthesis of N‐phenylmaleimide in a MW and in an oil bath at 144 °C (boiling xylene).     

Efficient diverse approach for quinoxaline‐derived glycosylated and morphinylated analogs

Sulfanyl‐glycosides have been synthesized by reaction of 2,3‐dimercaptoquinoxaline ( 1 ) with acetohalo sugars in presence of base to give the thioglycosides‐derived quinoxalines 5 , 6 , 7 and 9 . Similarly, the acyclic analogs 23 , 24 , 25 , 26 were prepared by coupling of 1 with different acyclo‐alkylating agents. The preparation of 3‐morpholinyl‐quinoxalines 10 and 11 allowed the synthesis of 3‐glycosylsulfanyl‐2‐morpholinyl‐quinoxalines 12 , 13 , 14 and 17 as well as the acyclic analogs 27 , 28 , 29 . Microwave irradiation of the reactants turned out to be preferred over the conventional method for achieving the synthetic goals. This study made an available venue to the synthesis of diverse quinoxaline derivatives. J. Heterocyclic Chem., 2011.     

Polarity‐based fractionation in proteomics: hydrophilic interaction vs reversed‐phase liquid chromatography

During recent decades, hydrophilic interaction liquid chromatography (HILIC) ahs been introduced to fractionate or purify especially polar solutes such as peptides and proteins while reversed‐phase liquid chromatography (RPLC) is also a common strategy. RPLC is also a common dimension in multidimensional chromatography. In this study, the potential of HILIC vs RPLC chromatography was compared for proteome mapping of human peripheral blood mononuclear cell extract. In HILIC a silica‐based stationary phase and for RPLC a C₁₈ column were applied. Then separated proteins were eluted to an ion trap mass spectrometry system. Our results showed that the HILIC leads to more proteins being identified in comparison to RPLC. Among the total 181 identified proteins, 56 and 38 proteins were fractionated specifically by HILIC and RPLC, respectively. In order to demonstrate this, the physicochemical properties of identified proteins such as polarity and hydrophobicity were considered. This analysis indicated that polarity may play a major role in the HILIC separation of proteins vs RPLC. Using gene ontology enrichment analysis, it was also observed that differences in physicochemical properties conform to the cellular compartment and biological features. Finally, this study highlighted the potential of HILIC and the great orthogonality of RPLC in gel‐free proteomic studies. Copyright © 2015 John Wiley & Sons, Ltd.     

Multi swarms for neighbor selection in peer-to-peer overlay networks

Peer-to-peer (P2P) topology has a significant influence on the performance, search efficiency and functionality, and scalability of the application. In this paper, we investigate a multi-swarm approach to the problem of neighbor selection (NS) in P2P networks. Particle swarm share some common characteristics with P2P in the dynamic socially environment. Each particle encodes the upper half of the peer-connection matrix through the undirected graph, which reduces the search space dimension. The portion of the adjustment to the velocity influenced by the individual’s cognition, the group cognition from multi-swarms, and the social cognition from the whole swarm, makes an important influence on the particles’ ergodic and synergetic performance. We also attempt to theoretically prove that the multi-swarm optimization algorithm converges with a probability of 1 towards the global optima. The performance of our approach is evaluated and compared with other two different algorithms. The results indicate that it usually required shorter time to obtain better results than the other considered methods, specially for large scale problems.     

Amidoamine calix[4]resorcinarene-based oligomers and polymers as efficient sorbents of azo dyes from water

The sorption behaviour of three kinds of macrocyclic sorbents – amidoamine tetradodecyloxyphenylencalix[4]resorcinarene 1 and tetramethyloxyphenylencalix[4]-resorcinarene 2; composition of calix[4]resorcinarene 1+2, and novel P.1 and P.2 polymers with amidoamine calix[4]resorcinarene units towards three water-soluble azo dyes – methyl orange (MO), acid orange (AO5) and Congo red (CR) was studied. All sorbents form supramolecular complexes with the aforesaid dyes. The best sorbent for MO was shown to be polymer P.1, for the AO5 – composition 1+2 and for the CR – macrocycle 2, with high sorption capacities (373, 497 and 625 mg/g, respectively). The main factor in the binding of dyes by all studied sorbents proved to be surface electrostatic interactions. In addition to the Coulomb interactions, the most important factor for the polymers appeared to be the ‘net’ structure of the polymer with a high concentration of binding sites, providing electrostatic, hydrogen, dipole–dipole and hydrophobic interaction. Hydrophobic substituents in the sorbents exert a significant influence on the dye sorption. The increase of the sorbents' hydrophobicity leads to a lower sorption capacity for MO and CR and a higher sorption capacity for AO5. It was shown that sorption efficiency of the sorbent depends on the ‘dye–sorbent’ structure conformity.     

Eine neue volumetrisehe Bestimmung von kleinen Mengen Natrium

Ohne Zusammenfassung     

Simultaneous determination of ofloxacin and ornidazole in pharmaceutical preparations by capillary zone electrophoresis

A simple, rapid and validated capillary electrophoretic method has been developed for the separation and determination of ofloxacin and ornidazole in pharmaceutical formulations with detection at 230 nm. Optimal conditions for the quantitative separations were investigated. Analysis times shorter than 4 min were obtained using a background electrolyte solution consisting of 25 mmol/L phosphoric acid adjusted with 1 m Tris buffer to pH 8.5, with hydrodynamic injection of 5 s and 20 kV separation voltage. The validation criteria for accuracy, precision, linearity and limits of detection and quantitation were examined and discussed. An excellent linearity was obtained in concentration range 25–250 µg/mL. The detection limits for ofloxacin and ornidazole were 1.03 ± 0.11 and 1.80 ± 0.06 µg/mL, respectively. The proposed method has been applied for the analysis of ofloxacin and ornidazole both individually and in a combined dosage tablet formulation. The proposed validated method showed recoveries between 96.16 and 105.23% of the nominal contents. Copyright © 2009 John Wiley & Sons, Ltd.