Preparation of a dual-functionalized fumed silica nanoparticle catalysis for synthesis of azaluorenone derivatives

Research on Chemical Intermediates - A dual-functional silica-based catalyst was prepared by treating fumed silica with amino-containing silane then 1,4-butane sultone. The presence of functional...     

Quantum chemical study of the nature of interactions between the boraphosphinine and alumaphosphinine with some of the mono- and divalent cations: cation–π or cation–lone pair?

Structural Chemistry - Quantum chemical study of the nature of interactions between the boraphosphinine (BP) and alumaphosphinine (AlP) with some of the alkali metal cations (Li+, Na+, K+) and...     

Relationship of nanostructure and thermo-chemical response/thermal ablation of carbon aerogels

In this work, the interfacial mass balance relations combined with the non-parametric kinetic (NPK) analysis results were used for evaluating the thermo-chemical ablation process and oxidation mechanism of carbon aerogels with various porous structure. It was found that the two-parameter model of Nomen–Sempereis was able to describe the kinetics of the oxidation reaction and to reveal the structure-dependent contribution of two main processes with chemical and physical nature. The porosity of the carbon aerogel, rather than the other microstructural features, was realized more effective on the rate of ablation.     

Supercontinuum generation with femtosecond optical pulse compression in silicon photonic crystal fibers at 2500 nm

In this paper, femtosecond optical pulses compression and supercontinuum generation in a triangular silicon photonic crystal fiber at 2500 nm are investigated. A region of large minimum anomalous group velocity dispersion, negligible higher order dispersions and unique nonlinearity of silicon are used to demonstrate compression of 100 fs initial input optical pulses to 2.5 fs and ultra-broadband supercontinuum generation with very low input pulse energy over short distances of the fiber.     

A nearly zero temperature gradient furnace system for high pressure multi-anvil experiments

A new furnace system with an almost zero temperature gradient throughout the sample area was designed for multi-anvil high pressure experiments. Test experiments of the new design were performed using 18/11 and 25/15 cell assemblies at 4?GPa, 1400°C and 1500°C, respectively. The temperature field within the sample capsules appeared to be very homogenous as indicated by Mg₂Si₂O₆–MgCaSi₂O₆ two-pyroxene thermometry, by direct temperature measurements using two thermocouples within the same assembly, and by distribution of solid and liquid phases in the sample capsule. The temperature gradient is estimated to be <2.4°C/mm over an area of 4?×?5?mm² within the furnace. It is significantly lower than standard multi-anvil experiments with straight or stepped furnace systems, which are at the levels of 20–200°C/mm.     

Pyrophosphate Selective Recognition in Aqueous Solution Based on Fluorescence Enhancement of a New Aluminium Complex

A novel and simple fluorescence enhancement method for selective pyrophosphate(PPi) sensing was proposed based on a 1:1 metal complex formation between bis(8-hydroxy quinoline-5-solphonat) chloride aluminum(III) (Al(QS)₂Cl), (L) and PPi in aqueous solution. The linear response range covers a concentration range of 1.6 × 10⁻⁷ to 1.0 × 10⁻⁵ mol/L of PPi and the detection limit of 2.3 × 10⁻⁸ mol/L. The association constant of L-PPi complex was calculated 2.6 × 10⁵ L/mol. L was found to show selectively and sensitively fluorescence enhancement toward PPi over than I₃^-, NO₃^-, CN⁻, CO₃²⁻, Br⁻, Cl⁻, F⁻, H₂PO4⁻ and SO₄²⁻, which was attributed to higher stability of inorganic complex between pyrophosphate and L.     

Three-Component Reaction of Triphenylphosphine,Acetylenic Esters,and Arylsulfonyl Hydrazides or Aryl Hydrazines: An Efficient One-Pot Synthesis of Stable β-Nitrogen-Substituted Phosphorus Ylides

The three-component reaction between dialkyl acetylenedicarboxylates and triphenylphosphine in the presence of arylsulfonyl hydrazides or aryl hydrazines produces highly functionalized, salt-free phosphorus ylides in excellent yields.     

A non-adapted sparse approximation of PDEs with stochastic inputs

We propose a method for the approximation of solutions of PDEs with stochastic coefficients based on the direct, i.e., non-adapted, sampling of solutions. This sampling can be done by using any legacy code for the deterministic problem as a black box. The method converges in probability (with probabilistic error bounds) as a consequence of sparsity and a concentration of measure phenomenon on the empirical correlation between samples. We show that the method is well suited for truly high-dimensional problems.     

Characterization of a peptide family from the skin secretion of the Middle East Tree Frog Hyla savignyi by composition‐based de novo sequencing

A new tryptophyllin‐like peptide family was found in the skin secretion of the tree frog Hyla savignyi. Peptides were characterized by database‐independent sequencing strategies and specific ion fragmentation features were investigated. Skin secretions from specimens of Hyla savignyi were collected by mild electrical stimulation. Peptides were separated by reversed‐phase nano‐high‐performance liquid chromatography (nanoHPLC) and mass spectra were acquired online by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS). Peptides were characterized by manual de novo sequencing and by composition‐based sequencing (CBS), appearing mostly as C‐terminal free acids and as their acid amide analogs. Amide peptides yielded lower intensities of y‐type ions after collision‐induced dissociation (CID) than their acid analogs. A mechanism of internal b‐ion formation (positive ion mode) and of CO₂ elimination (negative ion mode) is proposed. We also exemplified phenomena such as the proline effect and formation of non‐direct sequence ions after sequence rearrangements. The occurrence of rearrangement products, of internal ions and of the proline effect made the CID spectra highly complex. CBS analysis nevertheless resulted in successful and highly reliable sequence analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

Three-Component Reaction of Triphenylphosphine,Dimethyl Acetylenedicarboxylate,and Aldehyde Benzoylhydrazones: An Efficient One-Pot Synthesis of Stable Phosphorus Ylides

Protonation of the reactive 1:1 intermediate produced in the reaction between dimethyl acetylenedicarboxylate and triphenylphosphine by benzoylhydrazones leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the NH acid to produce highly fanctionalized, salt-free phosphorus ylides in excellent yields.