Approximation of Fractional Brownian Motion by Martingales

We study the problem of optimal approximation of a fractional Brownian motion by martingales. We prove that there exists a unique martingale closest to fractional Brownian motion in a specific sense. It shown that this martingale has a specific form. Numerical results concerning the approximation problem are given.     

Tris(Trimethylsilyl)Phosphine in Reaction with Bis(Phenylenedioxa)Chlorophosphorane. The Way to Phosphoranylphosphines

Abstract

Tris(trimethy1silyl)phosphine (1) is the key reagent in the synthesis of one- and two-coordinated phosphorus compounds. Its characteristic features are extreme reactivity, high nucleophility of phosphorus atom and the P-Si bonds lability. The interaction of phosphine (1) with bis(catecho1)chlorophosphome (2) has been studied by dynamic ³¹P NMR method. On the reagents ratio 1:1 at first the nucleophilic substitution of chlorine occurs leading to formation of phosphome (3) with P^III-P^v bond (σ_P(III) -117.0, σ^P(V) 17.4 ppm, ¹J_pp 305.0 Hz) which converts then into more stable 2-(trimethylsiloxyphenyloxy)-4,5-bem- 1,3,2-dioxaphospholane (4).     

Improving the sensitivity of a humidity sensor based on fiber bend coated with a hygroscopic coating

A highly sensitive all-fiber humidity sensor is demonstrated. The sensor behaves as a humidity dependent optical switch between 85% and 90% RH. This sensor also offers the advantages of simple structure and low cost and its response is fast and reversible in nature. The typical humidity response of the sensor is suitable for using it as a human breath rate monitor.     

The role of physical and chemical properties of Pd nanostructured materials immobilized on inorganic carriers on ion formation in atmospheric pressure laser desorption/ionization mass spectrometry

Fundamental parameters influencing the ion‐producing efficiency of palladium nanostructures (nanoparticles [Pd‐NP], nanoflowers, nanofilms) during laser irradiation were studied in this paper. The nanostructures were immobilized on the surface of different solid inorganic carrier materials (porous and mono‐crystalline silicon, anodic porous aluminum oxide, glass and polished steel) by using classical galvanic deposition, electroless local deposition and sputtering. It was the goal of this study to investigate the influence of both the nanoparticular layer as well as the carrier material on ion production for selected analyte molecules. Our experiments demonstrated that the dimensions of the synthesized nanostructures, the thickness of the active layers, surface disorders, thermal conductivity and physically or chemically adsorbed water influenced signal intensities of analyte ions during surface‐assisted laser desorption/ionization (SALDI) while no effects such as plasmon resonance, photoelectric effect or catalytic activity were expected to occur. Excellent LDI abilities were seen for Pd‐NPs immobilized on steel, while Pd nanoflowers on porous silicon exhibited several disadvantages; viz, strong memory effects, dependency of the analytical signal on amount of physically and chemically adsorbed water inside porous carrier, reduced SALDI activity from unstable connections between Pd and semiconductor material, decrease of the melting point of pure silicon after Pd immobilization and resulting strong laser ablation of metal/semiconductor complex, as well as significantly changed surface morphology after laser irradiation. The analytical performance of Pd‐NP/steel was further improved by applying a hydrophobic coating to the steel surface before galvanic deposition. This procedure increased the distance between Pd‐NPs, thus reducing thermal stress upon LDI; it simultaneously decreased spot sizes of deposited sample solutions. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and Comparison of the Reactivity of 3,4,5‐1H‐Trinitropyrazole and Its N‐Methyl Derivative

3,4,5‐Trinitro‐1H‐pyrazole ( 1 ) has been obtained via nitration of 3,5‐dinitropyrazole with mixture of sulfuric and nitric acids. Compound 1 reacts with excess ammonia and aliphatic amines, in the presence of bases with NH‐azoles, phenols, thiols, and triflouroethanol at mild conditions in water. All these reactions occur as the nucleophilic substitution of the nitro‐group at position 4 in 1 affording 4‐R‐3,5‐dinitropyrazoles. The product of methylation of 1 , N‐methyl‐3,4,5‐trinitropyrazole ( 4 ), also reacts with thiols, phenols, oximes, ammonia, amines, and NH‐azoles. The reactions proceed with high yields but nucleophilic substitutions in these cases occur regioselectively at position 5 in 4 to afford 5‐R‐3,4‐dinitropyrazoles.     

Self-assembled dendrimers with uniform structure

Calix[4]arenes substituted at their wide rim by four aryl urea residues (1) form hydrogen-bonded dimers in apolar solvents. Replacement of one urea residue by an acetamido moiety leads to calix[4]arene derivatives (5) which form hydrogen-bonded tetramers under the same conditions. Both self-assembly processes occur independently. Therefore, molecules have been prepared in which a tetra-urea calix[4]arene and a tri-urea mono acetamide derivative are covalently connected between their narrow rims by a long, mainly aliphatic chain [-O-(CH(2))(n)-C(O)-NH-(CH(2))(m)-O-] (7). In the presence of an equimolar amount of tetra-tosyl urea calix[4]arene () they form dendritic assemblies since the well known heterodimerization of tetra-tosyl and tetra-aryl urea calix[4]arenes prevents the formation of a cross-linked structure. Covalent connection of adjacent urea residues leads to tetra-loop derivatives (3) that cannot form homodimers, but instead form heterodimers with tetra-aryl or tetra-tosylureas. Therefore, similar dendrimers should be available using the selective dimerization observed for 3. The formation of a single, structurally uniform dendrimer from eight building blocks is confirmed by (1)H NMR spectra, showing only peaks that are also found for respective model assemblies. Translational diffusion coefficients of the assemblies have been determined using (1)H DOSY NMR.     

Anti-Inflammatory Effect of Phytoncide in an Animal Model of Gastrointestinal Inflammation

Background: Phytoncide is known to have antimicrobial and anti-inflammatory properties. Purpose: This study was carried out to confirm the anti-inflammatory activity of two types of phytoncide extracts from pinecone waste. Methods: We made two types of animal models to evaluate the efficacy, an indomethacin-induced gastroenteritis rat model and a dextran sulfate sodium-induced colitis mouse model. Result: In the gastroenteritis experiment, the expression of induced-nitric oxide synthase (iNOS), a marker for inflammation, decreased in the phytoncide-supplemented groups, and gastric ulcer development was significantly inhibited (p < 0.05). In the colitis experiment, the shortening of the colon length and the iNOS expression were significantly suppressed in the phytoncide-supplemented group (p < 0.05). Conclusions: Through this study, we confirmed that phytoncide can directly inhibit inflammation in digestive organs. Although further research is needed, we conclude that phytoncide has potential anti-inflammatory properties in the digestive tract and can be developed as a functional agent.     

Sorption Catalytic Determination of Copper(II) and L-α-alanine on Mg-, Al-Layered Double Hydroxides

Mg-, Al and Mg-, Cu-, Al-layered double hydroxides well-known synthetic hydrotalcite-like sorbents, were used for the first time as carriers for indicators in the sorption catalytic determination of copper(II) and L-α-alanine. Mg-, Al and Mg-, Cu-, Al-layered double hydroxides were synthesized by coprecipitation and characterized using infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The adsorption of 0.50?mg?L^?1 copper(II) solution by Mg-, Al-layered double hydroxides followed a pseudo-second-order model with an equilibrium sorption capacity of 24.2?×?10^?3?mg?g^?1 (3.8?×?10^?4?mmol g^?1) and a reaction rate constant of 4.2?g mg^?1?min^?1. Mg-, Al-layered double hydroxide tablets were prepared and used for sorption concentration and subsequent sensitive and selective sorption catalytic determination of 5.5?×?10^?3 to 1.0?mg?L^?1 copper(II) at the sorbent phase. The method was used for the analysis of natural water. A method was developed for the determination of α-alanine in Mg-, Cu-, Al-layered double hydroxide tablets with a limit of detection of 4.0?×?10^?3 mol?L^?1. In addition, thin layers of Mg-, Cu-, Al-layered double hydroxide were used to separate α-alanine and determine α-amino acids by thin-layer chromatography.