Fabrication of Functionally Graded SiAlON Ceramics by Tape Casting

Functionally graded SiAlON ceramics (FG-SiAlONs) were successfully prepared by the tape casting and lamination approach. Non-aqueous SiAlON slurries with five different α to β-SiAlON ratios (85α:15β, 70α:30β, 55α:45β, 40α:60β, and 25α:75β) were prepared by a 66 methyl ethyl ketone/34 ethanol (vol%) mixture. Phase and microstructure analyses incorporation with hardness measurements clearly show that the FG-SiAlONs, prepared by tape casting, exhibit a continuous and gradual change in composition and hardness. Thus, the tape casting approach is a viable method to produce FG-SiAlONs with a precisely controlled composition, and subsequently properties, as a function of position.     

An investigation of the synthesis and thermal stability of poly(dl-lactide)

Summary The synthesis and thermal degradability of poly (DL-lactide) were investigated. Key factors affecting the polymer molecular weight were found to be monomer recrystallization, initiator concentration and the vacuum level during drying/sealing of the polymerization reaction ampoule. It was found that poly (DL-lactide) is thermally unstable above its melting temperature. Monomer recrystallization, polymer precipitation and a low initiator content of the polymer significantly inhibited the rate and extent of thermal degradation.     

Technology adaptation: a typology for strategic human resource management

Organizational adjustment to technological change and its impact upon human resources should be based on an understanding of employee perceptions and behavioural responses to such developments. An analytic framework which relates strategic choice to internal labour market and employee determinism is derived from the methods employed by organizational theorists and psychologists to generate a set of typologies. The framework divides variables in four classes: (1) natural selection, with minimum choice and adaptation or selection out; (2) differentiation, with high choice and high employee determinism and adaptation within constraints; (3) strategic choice, with maximum choice and adaptation by design; and (4) undifferentiated choice, with incremental choice and adaptation by chance. Useful in reconciling previously inconsistent or incompatible theories of technological change, the framework is offered as a co-ordination device to integrate the results of divergent approaches to technological adaptation studies.     

Bologna process revisited: educating information security and malware experts

The Bologna process has resulted in the re- structuring of undergraduate and graduate education across Europe. This paper outlines what these changes mean for acquiring degrees in information security and how various universities have tried to respond to these demands. What is unclear at this stage is how the offering of continuous master degrees at Polytechnic and Applied Science Universities will affect the content and curriculum being taught in computer science and information security in particular. This question must be addressed since polytechnics are more industry focused and less research oriented than their university-counterparts. What seems to be clear at this stage is that continuous type master programs in computer science demand a greater level of mathematical knowledge than specialized masters. Moreover, due to the amount of credits that must be acquired, graduates of these types of programs will bring a deeper knowledge about the specialization such as, information security or malware, they acquired at university. This movement toward greater convergence in post secondary education may not have made things easier for recruiters, who are trying to hire graduates in information security or anti-virus experts. In fact, as this paper shows while the Bologna process may have eliminated the obvious differences, countless intricate and not so obvious differences have been added making it sometimes obscure for a bystander.     

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.

     

Processing of Particle-Stabilized Wet Foams Into Porous Ceramics

Direct foaming of colloidal suspensions is a simple and versatile approach for the fabrication of macroporous ceramic materials. Wet foams produced by this method can be stabilized by long-chain surfactants or by colloidal particles. In this work, we investigate the processing of particle-stabilized wet foams into crack-free macroporous ceramics. The processing steps are discussed with particular emphasis on the consolidation and drying process of wet foams. Macroporous alumina ceramics prepared using different consolidation and drying methods are compared in terms of their final microstructure, porosity, and compressive strength. Consolidation of the wet foam by particle coagulation before drying resulted in porous alumina with a closed-cell structure, a porosity of 86.5%, an average cell size of 35 μm, and a remarkable compressive strength of 16.3 MPa. On the other hand, wet foams consolidated via gelation of the liquid within the foam lamella led to porous structures with interconnected cells in the size range from 100 to 150 μm. The tailored microstructure and high mechanical strength of the macroporous ceramics can be of interest for the manufacture of bio-scaffolds, thermal insulators, impact absorbers, separation membranes, and light weight ceramics.     

Die Abtrennung von Ölsäuremonoglycerid aus einem Glyceridgemisch mit Hilfe eines überkritischen Extraktionsmittels

Separation of Glycerol-monooleate from a Mixture of Glycerides by Means of a Supercritical Extractant The continuous separation of pure monoglycerides out of a mixture of glycerides by means of supercritical fluid extraction was investigated. As supercritical extracting agent carbon dioxide containing propane as an entrainer was used. The phase equilibria concerning the process were measured and are discussed. In an extraction apparatus consisting of an extraction column and two separators the viability of the process was tested. At 40°C and 120 bar a product with 99.5 wt.% monoglycerides was manufactured out of a mixture of glycerides containing 59 wt.% monoglycerides.     

A greedy gradient-simulated annealing selection hyper-heuristic

Educational timetabling problem is a challenging real world problem which has been of interest to many researchers and practitioners. There are many variants of this problem which mainly require scheduling of events and resources under various constraints. In this study, a curriculum based course timetabling problem at Yeditepe University is described and an iterative selection hyper-heuristic is presented as a solution method. A selection hyper-heuristic as a high level methodology operates on the space formed by a fixed set of low level heuristics which operate directly on the space of solutions. The move acceptance and heuristic selection methods are the main components of a selection hyper-heuristic. The proposed hyper-heuristic in this study combines a simulated annealing move acceptance method with a learning heuristic selection method and manages a set of low level constraint oriented heuristics. A key goal in hyper-heuristic research is to build low cost methods which are general and can be reused on unseen problem instances as well as other problem domains desirably with no additional human expert intervention. Hence, the proposed method is additionally applied to a high school timetabling problem, as well as six other problem domains from a hyper-heuristic benchmark to test its level of generality. The empirical results show that our easy-to-implement hyper-heuristic is effective in solving the Yeditepe course timetabling problem. Moreover, being sufficiently general, it delivers a reasonable performance across different problem domains.