Mass Defect Filtering-Oriented Identification of Resin Glycosides from Root of Convolvulus scammonia Based on Quadrupole-Orbitrap Mass Spectrometer

This work aimed to develop and evaluate a post-acquisition data processing strategy, referred to as a mass defect filter (MDF), for rapid target the resin glycosides in root of Convolvulus scammonia by setting mass rang and mass defect range from high-resolution MS data. The full-scan mass data were acquired by high-performance liquid chromatography coupled with Q Exactive Plus hybrid quadrupole-orbitrap mass spectrometer that featured high resolution, mass accuracy, and sensitivity. To screen resin glycosides, three parent filter m/z 871, m/z 853, and m/z 869 combined with diagnostic fragment ions (DFIs) approach were applied to remove the interference from complex herbal extract. The targeted components were characterized based on detailed fragment ions. Using this approach, 80 targeted components, including 22 glycosidic acids and 58 resin glycosides were tentatively identified. The present results suggested that the proposed MDF strategy would be adaptable to the analysis of complex system in relevant filed.     

Synergistic extraction of Eu(III) and Nd(III) from aqueous medium using a mixture of sulfasalazine and 1,10-phenanthroline

Journal of Radioanalytical and Nuclear Chemistry - Solvent extraction of Eu(III) and Nd(III) from aqueous medium was investigated by sulfasalazine in benzoyl alcohol as single extractant and then...     

Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.     

Teaching complexity theory through student construction of a course wiki: The self‐organization of a scale‐free network

Complex systems are fascinating because emergent phenomena are often unpredictable and appear to arise ex nihilo. The other side of this fascination, however, is a certain difficulty in comprehending complex systems, particularly for students. To help students more fully understand emergence and self‐organization, a course on complexity theory was designed to not only be about these two concepts, but itself embody them. The principal design tool was a course wiki. Here, we quantitatively demonstrate that this course wiki self‐organized into a scale‐free network. This is particularly notable given the small size of the network. We conclude by noting a few qualitative examples of emergence, as well as offering recommendations for the future use of wikis in teaching complexity theory. © 2010 Wiley Periodicals, Inc. Complexity 16: 41–48, 2011     

Numerical Solution of Equation for Dynamic,Spontaneous Imbibition with Variable Inlet Saturation and Interfacial Coupling Effects

In the oil industry, dynamic spontaneous imbibition plays an important role in several flow processes in porous media. A numerical approach is developed to simulate dynamic spontaneous imbibition with variable inlet saturation and interfacial coupling. The inclusion of interfacial coupling effects invalidates the assumption that the interfaces (fluid/fluid and fluid/solid) act in the same way. The one-dimensional numerical simulation model is developed using a Lagrangian formulation discretized in time and saturation. The solution of the partial differential equations utilizes an iteration process that includes two material balance criteria to ensure the validity of the variable inlet saturation. Furthermore, an error analysis, the validation of the model and a sensitivity study on the optimal number of time steps and saturation grid cells are undertaken. The numerical simulation solution represents an accurate approach to investigate the effect of fluid and rock properties on dynamic spontaneous imbibition.     

Fabrication of highly sensitive cysteine electrochemical sensor based on nanostructured compound and carbon nanotube modified electrode

This work describes the electrochemical behavior of copper(II)-bis[5-((4-ⁿ-decyloxyphenyl)azo)-N-(ⁿethanol)-salicylaldiminato]film immobilized on the surface of multiwall carbon nanotube glassy carbon electrode and its electrocatalytic activity toward the oxidation of L-cysteine. The surface structure and composition of the sensor was characterized by scanning electron microscopy. Electrocatalytic oxidation of L-cysteine on the surface of modified electrode was investigated with cyclic voltammetry, chronoamperometry and hydrodynamic amperometery methods and the results showed that the Cu-Schiff base film displays excellent electrochemical catalytic activities towards L-cysteine oxidation. The modified electrode indicated reproducible behavior and high level of stability during the electrochemical experiments.     

One-Pot Tandem Synthesis of β-Trimethylsilyloxy Thioesters from Thioacids,Epoxides, and HMDS Catalyzed by Silica Gel Under Solvent-Free Conditions

A procedure for one-pot preparation of β-trimethylsilyloxy thioesters from epoxides, thioacids, and hexamethyl disilazane (HMDS) in the presence of silica gel under solvent-free condition was developed. The desired silylated products were isolated in good to excellent yields after silica-gel column chromatography.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Estimation of natural gas contribution in indoor 222Rn concentration level in residential houses

Journal of Radioanalytical and Nuclear Chemistry - The effect of natural gas use on indoor radon concentrations was studied in the dwelling of two cities in Cyprus using an AlphaGUARD radon...     

Enhanced epimerization of glycosylated amino acids during solid-phase peptide synthesis

Glycopeptides are extremely useful for basic research and clinical applications, but access to structurally defined glycopeptides is limited by the difficulties in synthesizing this class of compounds. In this study, we demonstrate that many common peptide coupling conditions used to prepare O-linked glycopeptides result in substantial amounts of epimerization at the α position. In fact, epimerization resulted in up to 80% of the non-natural epimer, indicating that it can be the major product in some reactions. Through a series of mechanistic studies, we demonstrate that the enhanced epimerization relative to nonglycosylated amino acids is due to a combination of factors, including a faster rate of epimerization, an energetic preference for the unnatural epimer over the natural epimer, and a slower overall rate of peptide coupling. In addition, we demonstrate that use of 2,4,6-trimethylpyridine (TMP) as the base in peptide couplings produces glycopeptides with high efficiency and low epimerization. The information and improved reaction conditions will facilitate the preparation of glycopeptides as therapeutic compounds and vaccine antigens.