Hydrolysis of cationic polyacrylamides

The alkaline hydrolysis of two acrylamide-based polyelectrolytes has been investigated. The experiments were carried out in buffered aqueous solutions in the pH range of 3.5–8.5 and in the temperature range of 22–50°C. ¹³C-NMR analysis of the hydrolysis product showed that choline chloride was the substance released upon hydrolysis. The decrease in charge density of the copolymer due to the hydrolysis was studied by polyelectrolyte titration and nitrogen analysis. The results show that the rate of hydrolysis increased with increasing pH or increasing temperature. In the hydrolysis of C-PAM 1 at 22°C and pH 6, the half-life of the cationic groups was 10 days. At pH 7 the half-life was shorter, 24 h, and at pH 8.5 the reaction was very fast with a half-life of about 0.25 h. The charged groups on C-PAM 2, the polymer with the higher charge density of the two polymers studied, have somewhat longer half lives than those on C-PAM 1. This can be explained by the structure of the polymers.     

Back to thinking mode: diaries for the management of information systems development projects

From a practical point of view, systems development methods are important sources of inspiration for the planning and establishment projects, but only to a limited extent do they support the reflections and actions of the participants. We propose the use of diaries as a supplement to conventional methods of reflection on what actually happens and what could happen during the course of a project, i.e., we propose diaries as a medium for the management of information systems development projects. This idea is based on an exploratory study carried out in co-operation with a bank and a research department, and the idea is supported by theoretical arguments from different fields. In conclusion, some practical advice on how to use diaries is given together with some questions for further investigation.     

Self-discharge of the alkaline iron electrode

The self-discharge reaction, which is a hydrogen-evolving corrosion process, where the anode reaction is identical to the first discharge step, has been studied by three different methods: H₂-evolution, polarization curves and potentiodynamic discharge. The influence of 28 additives at 30, 50 and 70°C on both discharge and self-discharge is shown. Most additives decrease both the self-discharge and discharge rates but for K₂S and hydrazinesulphate added to the electroylte. These two additives have a positive influence on the discharge process of the iron electrode.     

SURFACE MASS TRANSFER COEFFICIENTS FOR WOOD

Experimentally determined mass transfer coefficients for wood surfaces are often much lower than theoretically and experimentally determined coefficients for other surfaces. An investigation of this is made by comparing mass transfer coefficients for water and saturated non-wood surfaces, with coefficients measured for wood surfaces. It is found that measurements on wood surfaces are usually evaluated by assuming that Fick's law describes diffusion in wood. As this is not always true, it is proposed that the mass transfer coefficients measured on wood surfaces are low because the internal mass transfer in wood is not well understood. New measurements are presented which support this conclusiou.     

Educating reflective systems developers

Abstract. Systems development research shows that practitioners seldom follow methods and that the competencies required for successful development of computer‐based systems go well beyond those represented in contemporary methods. These insights make us question the role that methods should play in educating would‐be developers. Pedagogical theories, such as situated learning and double‐loop learning, complement these insights. Integrating the two, we argue that students need to complement the simplified accounts that methods express, with reflections on methods‐in‐use and on development practice in general. We present operationalizations of this idea in two quite different academic settings. Based on a retrospective analysis of our experiences in these settings, and a comparison and evaluation of the two approaches, we propose a number of lessons that can be used to improve the education of would‐be developers.     

Cortical Sensorimotor Interactions During the Expectancy of a Go/No-Go Task: Effects of Painful Stimuli.

The intent of this electroencephalography study was to investigate the competition between cortical nociceptive and cognitive-motor processes preceding sensorimotor interactions. Sensorimotor expectancy processes to painful stimulation and motor go/no-go demands were indexed over primary sensorimotor and midline cortical areas by contingent negative variation (CNV). Before the sensorimotor interaction, CNV was observed over midline posterior and bilateral central areas. Early expectancy of painful stimulation and the go/no-go task induced an evident midline posterior CNV. During the late expectancy period. CNV extended to the right central area contralateral to the stimulation. These findings suggest a sequential activation of midline posterior and primary sensorimotor areas contralateral to the painful stimulation as a reflection of the enhanced nociceptive processes preceding painful sensorimotor interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deactivation and regeneration of spent three-way automotive exhaust gas catalysts (TWC)

Topics in Catalysis - The effect of oxidation, oxy-chlorination and reduction treatments at elevated temperatures on the dispersion of palladium (Pd) and rhodium (Rh) for commercially aged...     

Einsatz moderner Berechnungsverfahren zur Analyse und Abwehr von Schäden

Improved Methods of Stress Analysis to Analyze and Prevent Failures The continuous rising demands on productivity and economy of modern processes, for example in the chemical or power generating industries, cause a tendency for permanent rise of the process parameters pressure and temperature. But for the engineer of a project rising process parameters mean an unproportional increase of the number of mechanical/thermal/chemical induced load collectives. During the basic design phase of a plant this aspect has to be taken into account with respect to the materials choice and the analysis of all mechanical, thermal and chemical induced load cases. In this article modern computer based stress analysis methods for the complex simulation of combined mechanical/thermal load cases are discussed using the example of pipe work. The emphasis was focussed on ?pipe work”? with respect to the new German pressure vessel code of April, 21 st., 1989. Since then within the framework of this code the integrity of pipe work has to be verified. Due to this demand a general discussion was initiated to validate the appropriate analysis method. In this article different examples were chosen to demonstrate the influence of complex load situations on the total stress level, for example the combination of external bending moments with stresses due to the mismatch of the physical properties of a selected material combination. Another goal of this paper is to show the demand for further investigations to transfer brand new scientific results to common engineering praxis. This aspect is discussed examining the failure behaviour of heat resistant steels under complex mechanical/thermal loading. It must be emphasized that the discussed analysis methods are not a paragraph in the German pressure vessel code. But these methods are necessary to assist the code in effective analysis and prevention of failures.