The role of additives towards increasing the SIMPLE SDD lifetime

The lifetime of a Superheated Droplet Detector (SDD) is limited by the fracture of the gel matrix, due to the growth of the bubble in time caused by Oswald ripening. There are several approaches to increasing the lifetime of a SDD by limiting the fracture phenomenon. We report, here, one of these approaches, which focuses on the gel itself. The lifetime of a SDD is increased if the fracture energy of the gel matrix is raised, leading to a better resistance to the fracture phenomenon. Several additives for the SDD gel were tested, with the results indicating the use of an agarose additive to extend the lifetime by as much as a factor 2.     

Corrosion of Si3N4-ceramics in aqueous solutions Part I: Characterisation of starting materials and corrosion in 1 N H2SO4

The corrosion behaviour of silicon nitride materials in acids strongly depends on the composition and amount of the grain boundary. But there exist no systematic investigations of the relation between the corrosion behaviour and the composition and amount of the grain-boundary phase. The aim of the series of these papers is the systematic investigation of these relations. In the first part the methods of determination of the amorphous grain-boundary phases are described in detail. Additionally, the correlation between the corrosion behaviour and the composition of the grain-boundary phases are given. The structural reasons and the mechanisms behind the observed changes in the corrosion behaviour will be given in part II of this paper.     

Chemical Oxidation Processes for Decolorization of Brown-Colored Molasses Wastewater

A study comparing the efficiency in decolorizing biologically pre-treated molasses wastewater of different oxidation processes using ozone, single hydrogen peroxide, Fenton's reagent and ozone combined with hydrogen peroxide has been performed. Ozone treatment was able to reduce about 76% of color. A combination of ozone with a low concentration of hydrogen peroxide was able to increase the color removal efficiency up to 89%. Gel permeation chromatography corroborated the reduction in the concentration of chromophore groups responsible for wastewater color. Single hydrogen peroxide and Fenton's reagent were not able to reduce color. Bicarbonate ions were found to be strong inhibitors of decolorizing reactions.     

GENERALIZED CORRESPONDING STATES CORRELATIONS FOR THE VISCOSITY AND THERMAL CONDUCTIVITY OF AQUEOUS ELECTROLYTE SOLUTIONS

Corresponding slates correlations have been developed for the viscosity and thermal conductivity of aqueous electrolyte solutions for a wide range of temperatures, pressures, and concentrations. For viscosity, the Vogel-Tamann-Fulcher equation has been generalized using the corresponding states theory, and extended to include pressure effects. Twenty six aqueous electrolyte solutions, including both monovalent and multivalent electrolytes, have been studied and a generalized correlation has been developed for viscosity, with four system dependent parameters. For thermal conductivity, a similar corresponding states based correlation has been developed. Twenty three aqueous electrolyte solutions were studied for thermal conductivity and a generalized equation was obtained that requires only two System dependent parameters. With both correlations, the maximum error is usually within 10% of the experimental values, with the average errors being much less. Additional systems can also be included in both correlations in a straightforward manner.     

Structure of poly(vinyl pyrrolidone) - C70 complexes in aqueous solutions

Aqueous solutions of poly(vinyl pyrrolidone)-fullerene complexes, PVP/C₇₀, have been studied using static and dynamic light scattering. Two diffusive processes were observed. The slow diffusion describes the motion of large PVP/C₇₀ clusters, whereas the fast diffusion is associated with the presence of single PVP molecules or small individual PVP/C₇₀ complexes of the order of a single PVP chain. The molar mass and the size of the PVP/C₇₀ clusters increase upon increasing the fullerene content. However, when the fullerene content is kept constant, an increase in the molar mass of the matrix PVP does not influence the mass and the size of the clusters. Dilution of the PVP/C₇₀ solutions has no effect on the clusters either. In PVP/C₇₀ there is a specific molar ratio of C₇₀ per repeating units of PVP that is same for all the samples studied.     

The effects of pH on the partitioning of aromatic acids in a polyethylene glycol/dextran aqueous biphasic system

Distribution ratios of acidic, neutral, and basic compounds were determined in polyethylene glycol (PEG)-6000/Dextran-75000 aqueous biphasic systems (ABSs) at incremental pH values. The nature of the solute species present at each pH was identified using speciation diagrams, and it was determined that the distribution ratios were related to their charge, with maximum distribution to the upper PEG-rich phase when the neutral species were dominant. The results suggest that this ABS is tunable with simple modifications of pH leading to increasing selectivity for specific target solutes.     

液化气脱硫组合工艺在50万吨·年^—1催化装置上的成功应用

主要阐述了液化气胺法脱硫和碱洗、水洗、砂滤、吸附等脱硫的组合工艺,彻底解决了液化气腐蚀不合格的问题。     

A study on the reaction kinetics of dendrimerization by FT-IR spectroscopy: Propagation of PAMAM dendrimer on silica gel

Solid-phase PAMAM dendrimer was synthesized by the repetitive addition of a branching unit to silica gel. All synthesis steps were monitored by infrared spectroscopy to investigate the reaction rate. Based on the measurements of infrared spectra, which showed the ester group varied as a function of reaction time, a reaction kinetics model was proposed and simulated. FT-IR and TGA measurements suggested that a ‘cross-linking’ reaction occurred in amidation process and generated structural defects, which decreased the grafted amount of dendrimer on silica gel. In addition, the analysis of reaction rate constants indicated that due to the formation of an intermediate, Michael addition of methyl acrylate to diamine was probably hindered by steric crowding. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.