An experimental and kinetic modeling study on the oxidation of 1,3-dioxolane

The modern catalytic or enzymatic advances allow the production of novel biofuel. Among them, 1,3-dioxolane can be produced from formaldehyde and ethylene glycol, both can be obtained from biomass. In this study, the oxidation of 1,3-dioxolane is studied at stoichiometric conditions. The ignition delay times of 1,3-dioxolane/O₂/inert mixtures were measured in a shock tube and in a rapid compression machine at pressures of 20 to 40 bar and temperatures ranging from 630 to 1300 K. The pressure profiles recorded in the rapid compression machine show a first stage of ignition enlightening the influence of the low temperature chemistry of combustion. Furthermore, mole fraction profiles of the stable intermediates produced during the oxidation of 1,3-dioxolane were measured in a jet-stirred reactor at 10 bar. Following these observations, a detailed kinetic model was developed with reaction rate coefficients and thermochemical data calculated by theoretical calculations or estimated by analogies to suitable molecules. In order to get an insight into the most important reaction pathways brute force sensitivity analysis and reaction pathway analysis were performed with the proposed model and discussed. It became clear that in the fuel-in-air case for the alkylhydroperoxide of 1,3-dioxolane the ring opening beta-scission pathway is favored against the further alkane-like second addition to molecular oxygen, which leads to a limited negative temperature coefficient.     

Developing Novel Antimicrobial and Antiviral Textile Products

In conjunction with an increasing public awareness of infectious diseases, the textile industry and scientists are developing hygienic fabrics by the addition of various antimicrobial and antiviral compounds. In the current study, sodium pentaborate pentahydrate and triclosan are applied to cotton fabrics in order to gain antimicrobial and antiviral properties for the first time. The antimicrobial activity of textiles treated with 3 % sodium pentaborate pentahydrate, 0.03 % triclosan, and 7 % Glucapon has been investigated against a broad range of microorganisms including bacteria, yeast, and fungi. Moreover, modified cotton fabrics were tested against adenovirus type 5 and poliovirus type 1. According to the test results, the modified textile goods attained very good antimicrobial and antiviral properties. Thus, the results of the present study clearly suggest that sodium pentaborate pentahydrate and triclosan solution-treated textiles can be considered in the development of antimicrobial and antiviral textile finishes.     

Approximate queueing models for capacitated multi-stage inventory systems under base-stock control

A queueing analysis is presented for base-stock controlled multi-stage production-inventory systems with capacity constraints. The exact queueing model is approximated by replacing some state-dependent conditional probabilities (that are used to express the transition rates) by constants. Two recursive algorithms (each with several variants) are developed for analysis of the steady-state performance. It is analytically shown that one of these algorithms is equivalent to the existing approximations given in the literature. The system studied here is more general than the systems studied in the literature. The numerical investigation for three-stage systems shows that the proposed approximations work well to estimate the relevant performance measures.     

Synthesis and characterization of novel antimicrobial cationic polyelectrolytes

Cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorhydrin (ECH) with benzyl amine (BA). Polyelectrolytes having different molecular weights were obtained by varying the ECH/BA mole ratio. Cationic polymers were characterized by ¹H-NMR and gel permeation chromatography. The antimicrobial activity of the polymers was tested against bacteria, yeast, and fungi.     

<Emphasis Type="Italic">q</Emphasis>-parabolicity of stratified pseudomanifolds and other singular spaces

The main result of this paper is a sufficient condition to have a compact Thom–Mather stratified pseudomanifold endowed with a \(\hat{c}\)-iterated edge metric on its regular part q-parabolic. Moreover, besides stratified pseudomanifolds, the q-parabolicity of other classes of singular spaces, such as compact complex Hermitian spaces, is investigated.     

Fouling behavior of microstructured hollow fiber membranes in dead-end filtrations: critical flux determination and NMR imaging of particle deposition

The fouling behavior of microstructured hollow fibers was investigated in constant flux filtrations of colloidal silica and sodium alginate. It was observed that the fouling resistance increases faster with structured fibers than with round fibers. Reversibility of structured fibers' fouling was similar during silica filtrations and better in sodium alginate filtrations when compared with round fibers. The deposition of two different silica sols on the membranes was observed by NMR imaging. The sols had different particle size and solution ionic strength and showed different deposition behaviors. For the smaller particle-sized sol in deionized solution (Ludox-TMA), there was more deposition within the grooves of the structured fibers and much less on the fins. For the alkali-stabilized sol Bindzil 9950, which had larger particles, the deposition was homogeneous across the surface of the structured fiber, and the thickness of the deposit was similar to that on the round fiber. This difference between the deposition behavior of the two sols is explained by differences in the back diffusion, which creates concentration polarization layers with different resistances. The Ludox sol formed a thick polarization layer with very low resistance. The Bindzil sol formed a slightly thinner polarization layer; however, its resistance was much higher, of similar magnitude as the intrinsic membrane resistance. This high resistance of the polarization layer during the Bindzil sol filtration is considered to lead to quick flow regulation toward equalizing the resistance along the fiber surface. The Ludox particles were trapped at the bottom of the grooves as a result of reduced back diffusion. The fouling behavior in sodium alginate filtrations was explained by considering the size-dependent deposition within the broad alginate size distribution. The better reversibility of fouling in the structured fibers is thought to be the result of a looser deposit within the grooves, which is more easily removed than a compressed deposit on the round fibers.     

EPR and optical studies of vanadium doped potassium dihydrogen citrate (C6H7KO7) single crystal

An EPR and optical studies of VO2+ doped potassium dihydrogen citrate (PDHC) single crystals have been carried out at room temperature. It crystallizes in triclinic symmetry with the unit cell dimensions: a=11.343?, b=13.078?, c=6.272?, α=89.79°, β=94.36°, γ=104.2°. The angular variation of EPR spectra have shown that two different VO2+ complexes are located in different chemical environments and each environment contains one magnetically VO2+ site occupying substitutional position in the lattice and show very high angular dependence.     

The Feynman–Kac formula for Schrödinger operators on vector bundles over complete manifolds

Methods from stochastic analysis are combined with functional analytic methods in order to prove a Feynman–Kac formula för Schrödinger type operators with nonnegative locally square integrable potentials on vector bundles over complete Riemannian manifolds. In particular, we obtain a Feynman–Kac–Itô formula on manifolds for Schrödinger operators with magnetic fields.     

Orbits and Test Elements in Free Leibniz Algebras of Rank Two

Let F be the free Leibniz algebra of rank two over a field K of characteristic zero freely generated by x ₁ and x ₂. In this article we show that an endomorphism of F which preserves the orbit of a nontrivial element of F is an automorphism. Using this result, we determine some test elements of F.     

Solvothermal synthesis of WO3/TiO2/carbon fiber composite photocatalysts for enhanced performance under sunlight illumination

Carbon fiber (CF)‐based WO₃/TiO₂ composite catalysts (WO₃/TiO₂/CF) were successfully synthesized by solvothermal method. The catalysts were characterized by XPS, SEM, BET, XRD, FTIR, Raman and UV–Vis. The analyses confirmed the WO₃/TiO₂ nanoparticles with high crystallinity deposited on the carbon structure. The photocatalytic degradation of Orange II azo dye under UV and sunlight illumination with the synthesized catalyst was explored. The composite catalyst displayed high performance (85%) for Orange II degradation while that of for WO₃/TiO₂ was found as 76%. The effects of CF amount, solution pH, initial dye concentration and catalyst dose on photocatalytic performance were studied. It was found that the degradation efficiency increased from 68% to 90% with the increasing CF amount from 3 wt% to 5 wt%, while the further increase in CF amount (7–10 wt%) decreased the photodegradation due to the blocking the active sites of WO₃/TiO₂. The enhanced photocatalytic efficiency was mainly attributed to the electrical properties of the CF and reduced bandgap.