A versatile thiouronium-based solid-phase synthesis of 1,3,5-triazines

A thiouronium-based solid-phase synthesis of a 1,3,5-triazine scaffold has been developed. The key feature of the synthesis is the use of a readily accessible solid-supported thiouronium salt as a primary precursor for the stepwise assembly of the 1,3,5-triazine substrate. The sulfur linker employed in the synthesis is stable under both acidic and basic conditions and is versatile enough to provide access to monocyclic, bicyclic, and spirocyclic compounds with the 1,3,5-triazine scaffold. By using this synthetic strategy, a representative set of 79 compounds containing the 1,3,5-triazine scaffold were prepared.     

A multiplex lectin-channel monitoring method for human serum glycoproteins by quantitative mass spectrometry

A mass profiling method and multiple reaction monitoring (MRM)-based quantitative approach were used to analyze multiple lectin-captured fractions of human serum using different lectins such as aleuria aurantia lectin (AAL), phytohemagglutinin-L(4) (L-PHA), concanavalin A (Con A), and Datura stramonium agglutinin (DSA) to quantitatively monitor protein glycosylation diversity. Each fraction, prepared by multiple lectin-fractionation and tryptic digestion, was analyzed by 1-D LC-MS/MS. Semi-quantitative profiling showed that the list of glycoproteins identified from each lectin-captured fraction is significantly different according to the used lectin. Thus, it was confirmed that the multiplex lectin-channel monitoring (LCM) using multiple lectins is useful for investigating protein glycosylation diversity in a proteome sample. Based on the semi-quantitative mass profiling, target proteins showing lectin-specificity among each lectin-captured fraction were selected and analyzed by the MRM-based method in triplicate using each lectin-captured fraction (average CV 7.9%). The MRM-based analysis for each lectin-captured fraction was similar to those obtained by the profiling experiments. The abundance of each target protein measured varied dramatically, based on the lectin-specificity. The multiplex LCM approach using MRM-based analyses is useful for quantitatively monitoring target protein glycoforms selectively fractionated by multiple lectins. Thus through multiplex LCM rather than single, we could inquire minutely into protein glycosylation states.     

Reactive Compatibilization of Poly(trimethylene terephthalate)/Polypropylene Blends by Polypropylene‐graft‐Maleic Anhydride. Part 2. Crystallization Behavior

The crystallization behavior of uncompatibilized and reactive compatibilized poly(trimethylene terephthalate)/polypropylene (PTT/PP) blends was investigated. In both blends, PTT and PP crystallization rates were accelerated by the presence of each other, especially at low concentrations. When PP content in the uncompatibilized blends was increased to 50–60 wt%, PTT showed fractionated crystallization; a small PTT crystallization exotherm appeared at ～135°C besides the normal ～175°C exotherm. Above 70 wt% PP, PTT crystallization exotherms disappeared. In contrast, PP in the blends showed crystallization exotherms at 113–121°C for all compositions. When a maleic anhydride‐grafted PP (PP‐g‐MAH) was added as a reactive compatibilizer, the crystallization temperatures (T _c ) of PTT and PP shifted significantly to lower temperatures. The shift of PTT's T _c was larger than that of the PP, suggesting that addition of the PP‐g‐MAH had a larger effect on PTT's crystallization than on PP due to reaction between maleic anhydride and PTT.

The nonisothermal crystallization kinetics was analyzed by a modified Avrami equation. The results confirmed that PTT's and PP's crystallization was accelerated by the presence of each other and the effect varied with blend compositions. When the PP content increased from 0 to 60 wt%, PTT's Avrami exponent n decreased from 4.35 to 3.01; nucleation changed from a thermal to an athermal mode with three‐dimensional growths. In contrast, when the PTT content increased from 0 to 90 wt% in the blends, changes in PP's n values indicated that nucleation changed from a thermal (0–50 wt% PTT) to athermal (60–70 wt% PTT) mode, and then back to a thermal (80–90 wt% PTT) mode. When PP‐g‐MAH was added as a compatibilizer, the crystallization process shifted considerably to lower temperatures and it took a longer crystallization time to reach a given crystallinity compared to the uncompatibilized blends.     

A finite volume unstructured multigrid method for efficient computation of unsteady incompressible viscous flows

An unstructured non‐nested multigrid method is presented for efficient simulation of unsteady incompressible Navier–Stokes flows. The Navier–Stokes solver is based on the artificial compressibility approach and a higher‐order characteristics‐based finite‐volume scheme on unstructured grids. Unsteady flow is calculated with an implicit dual time stepping scheme. For efficient computation of unsteady viscous flows over complex geometries, an unstructured multigrid method is developed to speed up the convergence rate of the dual time stepping calculation. The multigrid method is used to simulate the steady and unsteady incompressible viscous flows over a circular cylinder for validation and performance evaluation purposes. It is found that the multigrid method with three levels of grids results in a 75% reduction in CPU time for the steady flow calculation and 55% reduction for the unsteady flow calculation, compared with its single grid counterparts. The results obtained are compared with numerical solutions obtained by other researchers as well as experimental measurements wherever available and good agreements are obtained. Copyright © 2004 John Wiley & Sons, Ltd.     

Intercalation of Toluidines into α-Zirconium Hydrogenphosphate

Intercalates of o-, m-, and p-toluidine into α-Zr(HPO₄)₂ · H₂O were prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As follows from IR, toludine molecules are protonated in the interlayer space. Toluidine molecules are arranged in a bimolecular way in the intercalates containing more than 1.5 toluidine molecules per Zr atom. On the other hand, a monolayer of the toluidine molecules is supposed in the intercalates with less than one toluidine molecule per Zr atom.     

Determination of Eupatilin in Human Plasma by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric method (LC-MS-MS) for the determination of eupatilin in human plasma has been developed. Eupatilin and an internal standard; (S)-N-(3-{3-fluoro-4-[6-(1-methyl-1H-tetrazol-5-yl)-pyridine-3-yl]-phenyl}-2-oxo-oxazolidin-5-ylmethyl)-acetamide (DA-7867) were extracted from human plasma by liquid-liquid extractionand analyzed on a phenyl-hexyl column using the mobile phase: acetonitrile-ammonium formate (10 mM, pH 3.0) (60:40, /). Analytes were detected using electrospray ionization-tandem mass spectrometry in multiple-reaction monitoring mode. The calibration curve was linear (r = 0.999) over the concentration range: 1.00–500 ng mL^–1 with a lower limit of quantification of 1.0 ng mL^–1 using a 100 L plasma sample. The precision (CV%) of this assay ranged: 2.4–7.0%, relative error: –7.0 to +2.0%. Recoveries of eupatilin ranged: 64.3–65.0%, with that of DA-7867 (internal standard) being 87.0 ± 5.3%.     

Thermodynamic study on molecular association of some organic dyestuffs in aqueous solution

The temperature effects on the absorption spectra of acridine orange and methylene blue in aqueous solution at various concentrations have been observed, and it was found that the increase in temperature has an effect on the spectra similar to that of the dilution. The heats of dimerization of the dyestuffs in aqueous solution have been measured directly by the calorimetric titration method, and ΔH_d for acridine orange and methylene blue were found to be ?49.6 and ?83.3 kJ mol^?1, respectively. The entropy of dimerization values were also calculated to be ΔS_d = ?54.9 and ?211.6 J K^?1 mol^?1 for acridine orange and methylene blue, respectively. It has been concluded that the stacking interactions are primarily responsible for the self-association of the dye molecules.     

3D/2D multidimensional perovskites: Balance of high performance and stability for perovskite solar cells

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