Identification and characterization of fenton oxidation products of surfactants by electrospray mass spectrometry and by solid phase microextraction gas chromatography mass spectrometry. 2. Fatty alcohol polyethoxy sulphates

The Fenton reaction for the degradation of surfactants has been investigated and partial degradation products have been identified and characterized by mass spectrometry for the case of fatty alcohol polyethoxy sulphates. The polar water-soluble products were investigated by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI), and the volatile products leaving the mixture during the reaction were trapped by means of solid phase microextraction (SPME) and investigated by gas chromatography/mass spectrometry (GC/MS) with electron and chemical ionization. The oxidation leads to the formation of products with hydroxyl and epoxide groups due to insertion of oxygen atoms or with terminal ethoxylic moieties deriving from the loss of the hydrophilic sulphate group. The formation of volatile aldehydes is also observed, corresponding to the fragmentation between hydrocarbon and ethoxylic chains. The extent of mineralization is dependent on peroxide and iron(II) concentrations. Copyright 2000 John Wiley & Sons, Ltd.     

International Review of Science Solid State Chemistry,Inorganic Chemistry Series Two,Vol. 10 : Consultant Editor H.J. Emeleus FRS,Volume Editor L.E.J. Roberts,Butterworths, London, 1975, pp. 264, price £13.00

Complexes of nicotinic and isonicotinic acids and their deuterated analogues with pyridine, 4-Me pyridine and N Me imidazole have been examined by IR spectroscopy. Strong hydrogen bonding between an O atom of the acid and the N atom of the base with the H atom lying closer to the O atom, is present in all systems.     

Kinetics of calcium phosphate reduction by carbon

A fundamental study was made on the reduction of calcium phosphate by carbon. The mechanism of reduction was presented on applying different additions. Both silica and alumina increased the extent of reduction but with variable rates. The activation energies were calculated on the basis of first-order reactions. The phases formed during reduction were investigated by X-ray analysis.     

Kinetics and electrochemical studies on superoxide

Rate constants for the reaction of superoxide O^- ₂ with various substrates were obtained through stationary electrode polarography theory and technique. In solvent acetonitrile, the substrate and the rate constants of the reaction O^- ₂ + AH^{- k2}Product, are, AH = isopropanol (k₂ < 0.01 M^-1 s^-1); ethanol (k₂ = 1.42 × 10² M^-1 s^-1); methanol (k₂ = 1.1 × 10⁷ M^-1 s^-1), H₂O (k₂ = 1.0 × 10⁵ M^-1 s^-1). In MeCN, O^-2 was found to be rather unreactive towards glucose and acetone but it reacts with fructose and sucrose catalytically. However, in DMF2, O^- ₂reacts with glucose and fructose with k2 order of 105 M-1 s-1. The mechanism of the reaction of O^- ₂ with the substrates (AH) is proposed as O^- ₃ + AH k₂O, AH^k2 _k-1 k [O₂H + AH]^-, _k-2O₂H + A^- with k₁ = 10⁹ M^-1 s^-1 and k^-1 = 10⁸ -10⁹ s^-1. With these values of k_-1 and k₁, k k₂(obs). The reversible E_1/2 for O₂ + e O^- ₂ in various solvents: MeCN, acetone, isopropanol, methanol, H₂O were obtained either directly from the reversible voltammogram or from experimental voltammograms and the rate constants obtained (as above) using stationary electrode polargraphy theory; E_1/2 being -0.82 (MeCN),-0.85 (acetone),-0.72 (isopropanol);-0.66 (MeOH),-0.56 (H2O) vs SCE.     

Green synthesis and characterization of monodispersed silver nanoparticles obtained using oak fruit bark extract and their antibacterial activity

Green synthesis of silver nanoparticles (Ag NPs) has been achieved using oak fruit bark extract as a reducing, capping and stabilizing agent. The biosynthesized Ag NPs were characterized using various techniques. UV–visible spectrum of prepared silver colloidal solution showed absorption maximum at 433 nm. X‐ray diffraction and transmission electron microscopy analysis revealed that Ag NPs have a face‐centred cubic structure being spherical in shape with an average particle size of 20–25 nm. The toxicity of the Ag NPs was tested on bacterial species such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli by comparison based on diameter of inhibition zone in disc diffusion tests and minimum inhibitory concentration and minimum bactericidal concentration of NPs dispersed in liquid cultures. The antimicrobial activity of Ag NPs was greater towards Gram‐positive bacteria (S. aureus and B. subtilis) compared to Gram‐negative bacteria as determined using standard Kirby–Bauer disc diffusion assay and serial dilution. Copyright © 2016 John Wiley & Sons, Ltd.     

Inventory control and pricing for perishable products under age and price dependent stochastic demand

Multistage stochastic programming (SP) with both endogenous and exogenous uncertainties is a novel problem in which some uncertain parameters are decision-dependent and others are independent of decisions. The main difficulty of this problem is that nonanticipativity constraints (NACs) make up a significantly large constraint set, growing very fast with the number of scenarios and leading to an intractable model. Usually, a lot of these constraints are redundant and hence, identification and elimination of redundant NACs can cause a significant reduction in the problem size. Recently, a polynomial time algorithm has been proposed in the literature which is able to identify all redundant NACs in an SP problem with only endogenous uncertainty. In this paper, however, we extend the algorithm proposed in the literature and present a new method which is able to make the upper most possible reduction in the number of NACs in any SP with both exogenous and endogenous uncertain parameters. Proving the validity of this method is another innovation of this study. Computational results confirm that the proposed approach can significantly reduce the problem size within a reasonable computation time.