Preheating and vacuum metastability in supersymmetry

The constraints imposed by the requirement that the scalar potential of supersymmetric theories does not have unbounded directions and charge or color breaking minima deeper than the usual electroweak breaking minimum (EWM) are significantly relaxed if one just allows for a metastable EWM but with a sufficiently long lifetime. For this to be acceptable one needs however to explain how the vacuum state reaches this metastable configuration in the first place. We discuss the implications for this issue of the inflation induced scalar masses, of the supersymmetry breaking effects generated during the preheating stage as well as of the thermal corrections to the scalar potential which appear after reheating. We show that their combined effects may efficiently drive the scalar fields to the origin, allowing them to then evolve naturally towards the EWM.     

Incorporation of a new alkenyl‐based nonionic surfmer into acrylic latexes

The mechanisms by which a new nonionic alkenyl‐based surfmer (Maxemul 5011?) was involved in acrylic emulsion polymerization were investigated. No proof of homopolymerization or of chain transfer to surfmer was obtained under the conditions studied. The effect of the initiator type, feeding time of the surfmer, particle size of the seed, and surfmer concentration, on kinetics and surfmer incorporation showed that the surfmer reacted mainly by copolymerization with the monomers in the outer shell of the polymer particles. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4202–4211, 2004     

Determination of paracetamol and its four major metabolites in mouse plasma by reversed-phase ion-pair high-performance liquid chromatography.

A reversed-phase ion-pair high-performance liquid chromatographic method has been used for the separation of paracetamol and its four major metabolites (glucuronide, sulphate, cysteine and mercapturate conjugates) in mouse plasma samples. An ODS column was used and the mobile phase consisted of an aqueous solution of 0.01 M tetrabutylammonium chloride and 0.01 M Tris buffered to pH 5.0 with phosphoric acid, with methanol as the organic solvent. The gradient elution started with 30% methanol. After a delay of 0.5 min the methanol concentration was increased linearly to 75% over 7.5 min. The column was returned to the initial conditions after a delay of 1 min. A methanol solution of theophylline was added to the mouse plasma sample, centrifuged and immediately injected into the chromatographic system. The advantages of this method include good and rapid separation (last metabolite detected at 6.86 min), well resolved peaks, only a small amount of sample required for assay, adequate precision (no coefficient of variation was greater than 10% for paracetamol metabolites) and a high sensitivity (particularly for unchanged paracetamol and the cysteine conjugate).     

Differential pulse voltammetric study of the complexation of Cd(II) by the phytochelatin (γ-Glu---Cys)2Gly assisted by multivariate curve resolution

A multivariate curve resolution method by alternating least-squares (MCR-ALS) is applied to differential pulse voltammograms measured on the Cd(II)+(γ-Glu---Cys)₂Gly system as a model of metal–phytochelatin interactions at concentrations of both components in the range 10⁻⁷–10⁻⁵ mol l⁻¹. The course of complexation is different when peptide is titrated with metal from that when metal is titrated with peptide. The combined analysis of both matrices from titrations of peptide with metal and of metal with peptide allowed the resolution of the system. The analysis of the resulting pure voltammograms and concentration profiles of the resolved components suggested the presence of four different types of bound Cd(II) and made possible the formulation of a complexation model.     

Full-wave analysis of stripping chronopotentiograms at scanned deposition potential (SSCP) as a tool for heavy metal speciation: Theoretical development and application to Cd(II)-phthalate and Cd(II)-iodide systems

A new mathematical treatment has been developed and implemented in an EXCEL spreadsheet in order to determine average equilibrium functions from the full set of data measured by scanning stripping chronopotentiometry (SSCP) in solutions containing different proportions of heavy metal ions and small-sized ligands. It has been applied to the experimental systems Cd(II)-phthalate and Cd(II)-iodide as models of complexation in the absence and in the presence of electrodic adsorption, respectively. The good agreement between the complexation parameters determined in this way, those predicted from literature data and those obtained using a cadmium ion selective electrode (ISE) confirms the validity of the proposed methodology and encourages its further refining for the analysis of macromolecular and heterogeneous systems.     

Comparison of CP-PC-SAFT and SAFT-VR-Mie in Predicting Phase Equilibria of Binary Systems Comprising Gases and 1-Alkyl-3-methylimidazolium Ionic Liquids

This study compares performances of the Critical Point-based revision of Perturbed-Chain SAFT (CP-PC-SAFT) and the SAFT of Variable Range and Mie Potential (SAFT-VR-Mie) in predicting the available data on VLE, LLVE, critical loci and saturated phase densities of systems comprising CO, O₂, CH₄, H₂S, SO₂, propane, the refrigerants R22, R23, R114, R124, R125, R125, R134a, and R1234ze(E) and ionic liquids (ILs) with 1-alkyl-3-methylimidazolium ([C_nmim]⁺) cations and bis(trifluoromethanesulfonyl)imide ([NTf₂]⁻), tetrafluoroborate ([BF₄]⁻) and hexafluorophosphate ([PF₆]⁻) anions. Both models were implemented in the entirely predictive manner with k₁₂ = 0. The fundamental Global Phase Diagram considerations of the IL systems are discussed. It is demonstrated that despite a number of quantitative inaccuracies, both models are capable of reproducing the regularities characteristic for the considered systems, which makes them suitable for preliminary estimation of selectivity of the ILs in separating various gases.     

Cathodic stripping voltammetry of 2-mercaptoethanol

The behaviour of 2-mercaptoethanol at a hanging mercury drop electrode by cathodic stripping voltammetry (c.s.v.) is studied. The stripping curves are recorded by three scanning modes: rapid-scan direct-current, differential-pulse and fundamental harmonic alternating-current polarography. Under the recommended conditions, pre-electrolysis is done at a potential of 0.0 V vs. Ag/AgCl for 3 min in a medium of pH 6.7 or 8 (Britton-Robinson buffer). Then after 1 min, stripping is done at a scan rate of 6.6 mV s^?1 preferably in the differential-pulse mode. The stripping peak at about ?0.4 V is used to determine 2-mercaptoethanol within the concentration range 3 × 10^?8/2-8 × 10^?7 mol l^?1. Calibration functions are reported; the standard additions method is preferred near the limit of detection. The interferences of several organic compounds are described.