Color reactions of pyridines with pentacyanoamminoferrate

Trisodium pentacyanoamminoferrate is proposed as a spot test, chromatographic spray or spectrophotometric reagent for pyridines. A 1:1 colored complex of the reagent and pyridine derivative is formed in aqueous solution. The intensity and stability of the color varies with the pH.     

The synthesis of a leukotriene with SRS-like activity

The synthesis and biological characteristics of an SRS-like leukotriene are described.     

DYNGA: a general purpose QM-MM-MD program. I. Application to water

We present a general purpose QM-MM-MD engine (DYNGA) designed to test alternative hybrid Hamiltonians geared towards the treatment of problems of interest in structural biology including the use of experimental data constraints. In this first presentation we use DYNGA to explore the behaviour of a traditional QM-MM approach in the treatment of the water—water interaction. We find the potential energy hypersurface for the water dimer computed with the HF 4–31G*/TIP3P hybrid Hamiltonian tends to be too flat. We also explore the effect of using traditional QM-MM techniques on proton wires and conclude there is a need for improvement, possibly addressed by using polarizable force fields.     

PAST AND FUTURE MANAGEMENT OF A COLLAPSED FISHERY: THE BAY OF BISCAY ANCHOVY

Abstract We analyze the efficiency of the international management of the Bay of Biscay anchovy. While a sharing agreement between France and Spain has been in place since 1992, the fish stock collapsed in 2005 and the fishery closed from 2005 to spring 2010. We consider differences in production technologies between both countries and calibrate our model using data from 1987 to 2009. Our results suggest two sources of rent dissipation under the existing sharing agreement: inefficient quota allocation and production inefficiencies due to inflexible national regulations. We discuss several alternatives to improve management.     

ConFlo III - an interface for high precision delta(13)C and delta(15)N analysis with an extended dynamic range

A newly developed interface coupling a CHN combustion device (elemental analyser 'EA') to an isotope ratio mass spectrometer is described and evaluated. The purpose of the device is to extend the dynamic range of delta(13)C and delta(15)N analysis from less than 2 orders of magnitude to more than 3 orders of magnitude. Carbon isotope ratio measurements of atropine as a model compound have been performed analysing between 1 μg to 5 mg C with acceptable to excellent precision (0.6 to 0.06 per thousand, delta-notation). The correction due to the blank signal is critical for sample amounts smaller than 4 μg C. The maximum sample weight is determined by the combustion capacity of the EA. Larger sample amounts are measured using dilution of a small part of the EA effluent with helium. The dilution mechanism works virtually free of isotope fractionation. Copyright 1999 John Wiley & Sons, Ltd.     

Optimization of glucosinolate separation by micellar electrokinetic capillary chromatography using a Doehlert's experimental design

The aim of this study was to optimize by micellar electrokinetic chromatography the separation of four glucosinolates, i.e. sinigrin, glucobrassicin and methoxyglucobrassicin involved in Cruciferae resistance mechanisms and glucotropaeolin used as an internal standard. The separation borate buffer which contained sodium dodecyl sulphate, tetramethylammonium hydroxide and methanol was firstly optimized by using a three variable Doehlert experimental design. The optimum concentrations found enabled, for the first time, to obtain an acceptable resolution between the two indole glucosinolates, glucobrassicin and methoxyglucobrassicin. Modifications of the method such as a capillary pre-rinse with pure borate buffer and a step change in voltage during experiment were performed to improve the resolutions between glucosinolates and to reduce the analysis time. This method was validated by a statistical analysis and showed good linearity, repeatability and reproducibility.     

Effect of high voltage electrical discharges on filtration properties of Saccharomyces cerevisiae yeast suspensions

In the present work the dead-end filtration of Saccharomyces cerevisiae yeast suspensions disrupted by high voltage electrical discharges (HVED treatment) was investigated. The efficiency of disruption was evaluated using conductivity disintegration index of suspension Z (Z = 0–1) and absorbance spectra of supernatant solutions. The electronic microscopy study, particle sizing and measuring of ζ-potential and turbidity were used to characterize variation of the colloidal properties of a yeast suspension during disruption. The HVED treatment was found to cause an effective disruption of yeast cells and extraction of intracellular proteins and other bio-products. The study of filtration revealed suspension filterability deterioration after disruption. It was shown that filtration behaviour of the HVED-processed suspensions was governed by cake formation, the filtrate volume decreased and the cake resistance increased with increase of Z. For high levels of disruption (Z > 0.99), filtration was governed by membrane fouling. The optimal dosage of polycationic flocculant promoted the formation of flocks and accelerated filtration. However, selected flocculant (poly(diallyldimethylammonium chloride)) provoked binding of bio-product and was inappropriate for using as an agent enhancing extraction from disrupted yeast cells.