Degradation of ²-O-4 lignin model and related compounds by the ascomyceteChrysonilia sitophila (TFB 27441 strain)

Growth of the ascomyceteChrysonilia sitophila during degradation of lignin model dimers and monomers was compared to a glucose control. An inhibition of growth by Cα-carbonyl monomers and stimulation by β-O-4 lignin model and vanillyl alcohol were observed. A comparison of the degradation by this ascomycete with the basidiomycetePhanerochaete chrysosoporium showed similarities in relation to the type of degradation caused.     

A novel synthesis of thiazoles from dimethyl N-(ethoxycarbonylmethyl)imino dithiocarbonate, carbon disulfide and alkyl halides.

We report a new synthesis of thiazoles from a cyclocondensation reaction between dimethyl N-(ethoxycarbonylmethyl)iminodithiocarbonate (EMIC), carbon disulfide and alkylation of intermediate thiazole-2-thiolate with alkyl halides.     

Evidence for quasi-intramolecular acid-base reactions in solutions of transition metal ammine complexes

We have investigated the effect of temperature on the postulated quasi-intramolecular acid-base reactions in aqueous solutions of Cu(NH₃)₄(MnO₄)₂ and Ag(NH₃)₂ClO₄. Pure ammonium permanganate and perchlorate were obtained above 5 C and at room temperature, respectively, due to quasi-intramolecular acid-base reactions.     

Bounds for the generalized Marcum function of the second kind

The Ramanujan Journal - This paper provides elementary proofs for several types of congruences involving multipartitions and self-convolutions of the divisor function. Our computations use...     

Asymptotic Analysis of Finite-Source M/GI/1 Retrial Queueing Systems with Collisions and Server Subject to Breakdowns and Repairs

Methodology and Computing in Applied Probability - This paper deals with a retrial queuing system with a finite number of sources and collision of the customers, where the server is subject to...     

Organopolysiloxanes as Chemically Sensitive Coatings for Optical Fibers

Various types of UV-curable organically modified siloxanes have been synthesized by the sol-gel method with the aim of fabricating chemically sensitive coatings for silica optical fibers. The refractive index of the coating material can be tailored in the range from 1.46 to 1.56 and sensitivity towards CO2 is achieved by incorporation of amino groups. The interaction of the cured layers with CO2 or with hydrocarbons has been studied in immersion experiments. Both the reaction of CO2 with incorporated amino groups and the penetration of hydrocarbons into the layer induce changes of the light absorption coefficient and the refractive index of the coating which are detected by measuring the output light intensity from the fiber.     

Studies on the conversions of diols and cyclic ethers—49: Stereochemistry of cyclodehydration of 1,4-diols on the action of brönsted and lewis acids: a comprehensive study

The stereochemistry of the cyclodehydration of (±)- and meso-2,5-hexanediol on the action of various dehydrating agents was investigated. The earlier assumed and confirmed intramolecular S_N2 mechanism for acid-catalysed ring-closure was found to hold in most cases. Various extents of racemisation can be observed on the action of certain Lewis acids, and the solvents concentrated H₂SO₄ and HMPT (hexamethyl phosporic acid triamide) under previously unexamined reaction conditions.     

Titanium as a chemical modifier for the determination of cobalt in marine sediments

The determination of cobalt in marine sediments by electrothermal atomic absorption spectrometry was studied using no modifier and magnesium and titanium as modifiers. Titanium is one of the major sediment constituents, which widely affects the cobalt determination and it was studied as a chemical modifier since it was the only concomitant that increased the cobalt signal in the concentration range usually found in sediments. The performance of Mg and Ti as chemical modifiers was compared relative to maximum pyrolysis and atomization temperatures, linear calibration range, sensitivity and matrix effects. The pyrolysis curves showed that the analyte could be stabilized up to 1400 °C when either Ti or Mg(NO₃)₂ was present, while only 1000 °C could be used in the absence of a modifier. The optimum atomization temperature was 2500 °C in all cases. Analytical curves were compared using no modifier, 5 μg Ti and 100 μg Mg(NO₃)₂ as modifiers, and the linear range found was up to approximately 4 ng Co whether a modifier was used or not. With Ti as a chemical modifier, analytical curves for cobalt in aqueous solution and in a synthetic matrix resulted in the same sensitivity (m₀=55 pg), whereas the use of Mg led to characteristic mass values of 59 and 72 pg in aqueous solution and in a synthetic matrix, respectively, showing some matrix effect. The detection limits (3σ, n=10) were 0.4 μg g⁻¹ using no modifier and 0.3 μg g⁻¹ with Ti as a modifier in the original matrix. A reference estuarine sediment NIST 1646 with a non-certified content of 10.5 μg g⁻¹ Co was analyzed and the found value of 10.9±2.4 μg g⁻¹, (n=3), using Ti as chemical modifier and calibration against aqueous standards, was in good agreement with the recommended value.     

Simultaneous Determination of Ascorbic Acid and Uric Acid by Using a PVC/TTF‐TCNQ Composite Electrode as Detector in a FIA System

A PVC/TTF‐TCNQ composite electrode has been employed as detector in a flow injection system. The proposed method allows the simultaneous detection of ascorbic acid (AA) and uric acid (UA) in mixtures by using a FIA system in a simple manner, without pre‐treatment or modified electrode. This method is based on the amperometric determination of (a) ascorbic acid at 0.15 V and (b) both analytes at 0.35 V, being the response linear in the range 1×10^?2–4×10^?4 M for both analytes with detection limits (S/N=3) of 1.2×10^?4 M and 8.1×10^?5 M for AA and UA, respectively.