Mixtures of potassium sulphate and iron sulphate as catalysts for water vapour gasification of carbon: 3. Chemsitry of the in situ activation of the catalyst

Previously it was shown that certain mixtures of K₂SO₄ and FeSO₄ were excellent raw materials for catalytic water vapour gasification of carbon. It was suggested from the results that the iron salt catalyses the reduction of K₂SO₄ to K as the main catalyticly active species of gasification. This paper is concentrated on this activation process. Using TGA, DTA, ESCA, EPMA and visual observations of the melting behaviour after or during treatment of varying $\text{K}{}_2\text{SO}{}_4\text{FeSO}{}_4$ mixtures in H₂ and $\text{H}{}_2\text{H}{}_2\text{O}$ atmospheres it is found that elemental iron is formed in an early stage during heating up. This then catalyses the reduction of K₂SO₄ to K₂S, which is readily hydrolysed by water vapour to liquid KOH. K₂SO₄ and K₂S form an intermediate eutectic (m.p. = 610 °C), which favours wettability of the carbon surface and hydrolysis of K₂S. As well as FeSO₄ any iron salts can be used that are easily reduced to elemental iron in the gasification atmosphere. A general reaction scheme, including activation and catalytic gasification, is proposed. The activation of K₂SO₄ to catalytically active KOH can be described as follows: Fe-saltγFe3K₂SO₄ + 8Feγ3K₂S + 4Fe₂O₃Fe₂O₃ + 3H₂γ 2Fe + 3H₂OK₂S + H₂OγKHS+KOHKHS + H₂OγKOH + H₂S     

Chlorophyll Fluorescence Imaging for Monitoring the Effects of Minimal Processing and Warm Water Treatments on Physiological Properties and Quality Attributes of Fresh-Cut Salads

In this study, chlorophyll fluorescence imaging (CFI) was used to monitor plant stress induced by cutting of mini romaine lettuce (Lactuca sativa L. var. longifolia) and by cutting and washing of endive (Cichorium endivia L.) during storage. Regarding the more detailed study of endive fresh-cut salads, we additionally monitored respiratory activity, phenylalanine ammonia lyase (PAL) activity, contents of plant pigments, and cut edge browning. Determination of maximum quantum efficiency F _v/F _m was feasible through sealed consumer-sized film bags, thus, enabling the non-invasive monitoring of both fresh-cut salad types in the corresponding modified atmosphere during storage. Cutting of romaine lettuce provoked a partially reversible drop of F _v/F _m during the first 24 h. Subsequently, F _v/F _m of cut romaine strongly decreased with elapsing shelf life, whereas intact leaves exhibited only a slight decline. Regarding minimally processed endive, warm water washing progressively reduced F _v/F _m with increasing heat exposure, while respiratory activities and the content of accessory pigments remained unaffected. The heat-dependent decrease of F _v/F _m was correlated to the inhibition of the PAL activity. Mildly warm washing (40 °C, 120 s; 45 °C, 60 s) reduced PAL activities, while F_v/F_m remained widely unaffected and visual quality was only partially improved. However, warm water washing at elevated temperatures (45 °C, 120 s; 50 °C, 30–60 s) enabled maximum visual quality retention, accompanied by a significant decrease of F _v/F _m. CFI may represent a useful tool to monitor the stress conditions due to cutting and warm water treatments, hence, allowing the systematic improvement of fresh-cut produce.     

Bestimmung des Herbicids Glyphosat und dessen Hauptmetabolit Aminomethylphosphons?ure (AMPA) in Trinkwasser mit Hilfe der HPLC

Zusammenfassung Es wird eine Methode zur Bestimmung von Glyphosat und dessen Hauptmetabolit Aminomethylphosphonsäure (AMPA) in Trinkwasser beschrieben, die es erlaubt, den in der Schweiz geforderten Toleranzwert von 0,1 g/1 zu erreichen (Nachweisgrenze 0,02 g/l). Die Wasserprobe wird dabei direkt mit 9-Fluorenylmethyl-chloroformaat (FMOCCI) versetzt, um extrahierbare und gleichzeitig fluorescierende Derivate zu erhalten. Diese werden nach Ausschütteln mit einem organischen Lösungsmittelgemisch durch HPLC mit Fluorescenzdetektor bestimmt. In bisher 151 untersuchten Trinkwasserproben des Kantons Bern konnten weder Glyphosat noch AMPA nachgewiesen werden.

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Determination of glyphosate herbicide and its main metabolite aminomethylphosphonic acid (AMPA) in drinking water by HPLC

Summary A method for the determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) is described. With a detection limit of 0.02 g/l, the method suitably fulfills the requirements of the Swiss legislation (tolerance value of 0.1 g/l water). The compounds are derivatized directly in the original water sample with 9-fluorenylmethyl chloroformate (FMOCCI) in order to obtain extractable and fluorescent derivatives. These are extracted with organic solvents and determined by HPLC using a fluorescence detector. Neither of the compounds could be detected in 151 tap water samples from the Canton of Berne.

     

Carbon Dioxide Evolution and Moisture Evaporation During Roasting of Coffee Beans

ABSTRACT: Evolution of carbon dioxide and water vapor during roasting of coffee was followed in an isothermal high-temperature short-time and a low-temperature long-time roasting process. In addition, CO₂ release during storage of roasted beans was followed. CO₂ and water vapor concentration were assayed in the exhaust air by nondispersive infrared gas analysis. Although CO₂ evolution rates differed in the 2 processes, the final total amount of CO₂ released after 63 d of storage remained equal. CO₂ evolution and differentiation between evaporation of initial water and chemically formed water showed that chemical reactions leading to relevant amounts of CO₂ and water start at ap -proximately 180°C. A mass balance established on the present measurements was able to account fairly well for the gravimetrically measured roast loss.     

A self-adaptive universal receiver

In this paper we describe a new Self-Adaptive Re-Configurable Terminal, based on blind recognition of the system in use. This new terminal is operates thanks to a new radio interface receiver concept comprising two functional phases. These two phases are mapped on a specific architecture previously presented in [1]. The first one is devoted to a Wide Band Analysis (Wba) of the received signal in order to find which standard is being used. The second one being the demodulation itself. In this paper we focus on thisWba. It includes an iterative process in order to find the right bandwidth which has to be compatible with the Signal Processing techniques we use. During the last step of the process, blind standard recognition is performed by means of Radial Basis Function Neural Networks, which allow making full use of the analogy between our problem and conventional pattern recognition problems. Extensive simulation with true data of signals received in our lab has been performed and confirms the interest and efficiency of this type of recognition.     

Knowledge Workers for Information Support: Executives' Perceptions and Problems

Traditional executive information systems (EIS) user support tends to focus on technical support rather than information support. Letting executives use EIS directly for strategic information has not been successful. Adopting a combined method of case study and survey, this study explored and examined the role of information support functions from U.K. executives' point of view. It found that the use of information specialists for external information scanning, information refining, and information reporting has been perceived as important to support executives in acquiring strategic information. However, information specialists' knowledge and capability in sensing and interpreting information, executive culture, the cost of establishing such a support role are the main concerns of executives. the paper suggests that EIS users need information support, as opposed to technical support. To be effective and successful, managers' knowledge in sensing, interpreting, and using information should be elicited and shared among information specialists in light of knowledge management.     

Processing, physical and thermal properties of BlackglasTM matrix composites reinforced with NextelTM fabric

The cure and pyrolysis behavior of a BlackglasTM resin and NextelTM 440 impregnated with BlackglasTM resin were studied. Cure of the BlackglasTM resin is an exothermic process and DSC studies indicate that with an increase of catalyst content from 0.1 to 1.0%, the onset and peak temperature of cure are decreased coupled with an increase in the enthalpy of cure indicating a greater extent of cross linking. However, pyrolysis char yield of the pyrolyzate is relatively insensitive to cure conditions.Cure pressure and pyrolysis environment are variables in the processing of BlackglasTM matrix composite reinforced with NextelTM 440 Plain weave fabric. Variations in cure pressure from 30 to 80 psi had no discernible effect on the chemistry of the pryrolyzate. However, the higher cure pressure resulted in top and bottom ply damage. Pyrolysis in an Ar environment resulted in incorporationj of up to 12 wt % C of which 8 wt % as graphitic in nature in the ceramic matrix. Pyrolysis in NH3 resulted in 3.9 wt % nitrogen and 1.5 wt % carbon in the matrix, with all the nitrogen and carbon bonded to Si. The cured panels have to be pyrolyzed/densified between 6–7 times to achieve required density and porosity content. Oxidation behavior of the composites at 1000°C indicate that the argon pyrolyzed CMC's lose more weight due to decomposition of the pyrolytic carbon, whereas, NH3 pyrolyzed CMC's are stable as both the N and C are bonded to Si in the matrix. Dielectric constants K and K measured at 1 GHz in the as-processed condition are high in the argon pyrolyzed CMC, (K = 11–28) due to the presence of pyrolytic carbon. On the other hand NH3 pyrolyzed CMC exhibit low dielectric constant (K = 4). On oxidation, the dielectric constant in both the Ar and NH3 pyrolyzed panels is approximately 4.0.     

Nouveau type structural dans la chimie des phosphures : Le compose ternaire Ni20Zr6P13. Preparation,structure et proprietes

Two new compounds Ni₁₂Zr₂P₇ and Ni₂₀Zr₆P₁₃ were synthesized in the NiZrP system by reacting the constituent elements. Ni₁₂Zr₂P₇ is of the Fe₁₂Zr₂P₇-type while Ni₂₀Zr₆P₁₃ appears as a new structural type in the chemistry of transition metal phosphides. Its unit cell is hexagonal with space group P6̄ and contains one formula unit. The X-ray structure was studied from three-dimensional single-crystal counter data and was refined down to R = 0.040 for 221 independent reflections. The structure of Ni₂₀Zr₆P₁₃ can be described as built up by two groups of three phosphorus trigonal prisms occupied by the zirconium atoms. In each group, the |ZrP₆| prisms are linked together by common edges in order to generate triangular phosphorus sites occupied by nickel atoms. In addition, nickel atoms are also in tetrahedral and square-planar pyramidal phosphorus sites. A comparative study with the Fe₂P- and Co₄Hf₂P₃-type structures having the same metal/non metal ratio as in Ni₁₂Zr₂P₇ and Ni₂₀Zr₆P₁₃ is also discussed. A nearly temperature independent paramagetism and a metallic conduction deducted from magnetic and electrical measurements exhibit the metallic behavior for these new compounds.     

Surface spectroscopic studies of poly(methyl methacrylate) (PMMA) and modified PMMA surfaces

Multitechnique surface characterization of plasma and chemically modified poly(methyl methacrylate) (PMMA) is reported using Low Energy Ion Scattering Spectrometry (LEIS or ISS) and angular-dependent X-Ray Photoelectron Spectroscopy (XPS or ESCA). A complete picture of the depth, extent, and mechanism of modifications developed. ISS yields results, which especially complement ESCA because of the sensitivity to functional group arrangement due to shadowing and shielding of atoms in the topmost layer.