Stochastic Simulation of Droplet Interactions in Suspension Polymerization of Vinyl Chloride

In this paper a population balance based mathematical model is presented for describing suspension polymerization of vinyl chloride. The properties of the polymer product and the behaviour of the stirred batch polymerization reactor are investigated by simulation. Two-phase kinetics model of free radical polymerization is used, and heat balance is also included into the model. Beside the coalescence and breakage phenomena, are taken interchanges of species and heat between the droplets induced by collisions into account forming a complex threescale system. The motion of droplets in the physical space of the polymerization reactor, the breakage, coalescence and coalescence/ redispersion processes are simulated by using a coupled continuous time – Monte Carlo method

Kinetic Model Development of the Oligomerization of High Olefin Containing Hydrocarbon By-products to Clean Engine Fuels on Amberlyst Catalyst

Nowadays, since the demand for engine fuels is continuously changing, in petroleum refineries, increasing the flexibility of gasoline/middle distillate is still an important issue, e.g. by oligomerizing light olefins (3–6 carbon atoms). The aim of our work was to develop a valid kinetic model based on the extended Eley-Rideal mechanism to describe the oligomerization of the olefin content of light naphtha by fluidized catalytic cracking (FCC) on an ion-exchange resin. Experiments were carried out in a fixed-bed tubular reactor at temperatures of between 80 and 130 °C with liquid hourly space velocities (LHSV) of between 0.5 and 2.0 1/h using Amberlyst® 15 as a catalyst. The oligomerization process was characterized based on the composition of products determined by gas chromatography. The conversion of olefins and the selectivity of the oligomerization reactions forming C8-11 and C12+ hydrocarbons (C8-11 and C12+ selectivity; unit: relative %) were dependent on factors that determine the reactor performance in order to identify the kinetic model parameters. Given that the developed reactor model described the measured data reasonably accurately, it can be used in terms of the optimal design of an industrial oligomerization reactor

Modelling of heat exchange between drops in suspension polymerization of vinyl chloride

A population balance model is presented for suspension polymerization of vinyl chloride in a batch reactor to investigate the thermal properties of the system. Reactions are described using a simplified reaction model focusing on the heat generation of the highly exothermic polymerization reactions. The temperature of the continuous phase is assumed to be homogeneous over the reactor and the effects of some temperature rise of droplets due to the exothermic polymerization reactions and the possible heat exchange because of the coalescence/redispersion process are analysed. The population balance equation is solved applying a Monte Carlo method by coupling the deterministic polymerization reactions inside the droplets with the discrete event process induced by collisions of droplets. The results obtained by simulation show that rise in the temperature of droplets over the mean temperature of continuous phase lead to acceleration of the process. The possible size distribution of droplets and no smooth distribution of the initiator in those decrease the process efficiency

A fonológia és a morfológia analógia-alapú formális megközelítése = Analogy-based Formal Approach to Phonology and Morphology

'A fonológia és a morfológia analógia-alapú formális megközelítése' c. kutatás célja az volt, hogy szemben a generatív nyelvtanban (levezetéses változat vagy optimalitáselmélet) általánosan alkalmazott szabály-, vagy megszorítás?alapú elemzéssel, olyan megközelítéseket, elemzéseket dolgozzunk ki és alkalmazzunk a magyar morfológiára és fonológiára, melyeknek elsődleges formális eszköze az analógia, illetve, (általánosabban) hogy megvizsgáljuk az ilyen analógiás elemzés során felmerülő problémákat. Ez a cél jól illeszkedik a jelenlegi nemzetközi kutatásokhoz. Az elvégzett munka bebizonyította, hogy analógiás megközelítéssel elemezhetők a magyar morfológia és fonológia olyan problémái, melyek a hagyományos generatív elemzés számára nehézséget jelentenek (pl. a kötőhangzók, a defektív igék, a nem-produktív tőosztályok viselkedése, stb.). Ezzel kapcsolatban kísérleteteket is végeztünk, ezeknek egy része akusztikai fonetikai-percepciós jellegű volt (Bárkányi - Kiss), másik részük pedig a paradigmatikus hiányokra és a morfológiai tőosztályok kategorizációjára vonatkozott, illletve az igei paradigmán belüli analógiás viszonyokra (Lukács - Rebrus - Törkenczy). A kutatásnak nem volt célja egy általános analógiás modell kidolgozása. Azonosítottunk azonban általános problémákat, melyek minden ilyen modell esetén felmerülnek (ezek főleg a formális implementációval kapcsolatosak: pl. a hasonlóság ?számolása?, kvantifikálása, a gyakoriság szerepe, stb.) és egyszerű formában elkészült egy ?analógiás gép? is (Kálmán), amely analógiás aránypárokat tud kiszámolni és így szóalakokat tud megjósolni. | The main objective of the research ?Analogy-based Formal Approach to Phonology and Morphology? was to develop analyses of Hungarian morphology and phonology whose main formal tool is analogy ? as opposed to the usual generative approach which (in its derivational or Optimality Theoretic version) applies rules or constraints ? and to identify and examine problems that an analogical approach necessarily encounters. This objective fits in well with current international research in the theory of grammar. The work carried out has proved that an analogical approach to Hungarian morphology and phonology makes it possible to solve problems that cause difficulties for a traditional generative approach (e.g. linking vowels, paradigm gaps in verbal morphology, the categorisation of non-productive stem-classes ). We have carried out experiments, which were partly acoustic/perceptional phonetic nature (Bárkányi - Kiss) partly psycholinguistic (targeting paradigm gaps and stem-categorisation, Lukács - Rebrus - Törkenczy). We did not plan to work out a general model of analogy in grammar, but we identified general problems that such a model must face ? these mainly concerned formal implementation, e.g. the quantification of similarity, the role of (type and token) frequency ? and a simple ?analogical machine? was developed (Kálmán) which can calculate analogical proportions and predict word-forms

The effect of a preparation of minerals, vitamins and trace elements on the cardiac gene expression pattern in male diabetic rats

BACKGROUND: Diabetic patients have an increased risk of developing cardiovascular diseases, which are the leading cause of death in developed countries. Although multivitamin products are widely used as dietary supplements, the effects of these products have not been investigated in the diabetic heart yet. Therefore, here we investigated if a preparation of different minerals, vitamins, and trace elements (MVT) affects the cardiac gene expression pattern in experimental diabetes. METHODS: Two-day old male Wistar rats were injected with streptozotocin (i.p. 100 mg/kg) or citrate buffer to induce diabetes. From weeks 4 to 12, rats were fed with a vehicle or a MVT preparation. Fasting blood glucose measurement and oral glucose tolerance test were performed at week 12, and then total RNA was isolated from the myocardium and assayed by rat oligonucleotide microarray for 41012 oligonucleotides. RESULTS: Significantly elevated fasting blood glucose concentration and impaired glucose tolerance were markedly improved by MVT-treatment in diabetic rats at week 12. Genes with significantly altered expression due to diabetes include functional clusters related to cardiac hypertrophy (e.g. caspase recruitment domain family, member 9; cytochrome P450, family 26, subfamily B, polypeptide; FXYD domain containing ion transport regulator 3), stress response (e.g. metallothionein 1a; metallothionein 2a; interleukin-6 receptor; heme oxygenase (decycling) 1; and glutathione S-transferase, theta 3), and hormones associated with insulin resistance (e.g. resistin; FK506 binding protein 5; galanin/GMAP prepropeptide). Moreover the expression of some other genes with no definite cardiac function was also changed such as e.g. similar to apolipoprotein L2; brain expressed X-linked 1; prostaglandin b2 synthase (brain). MVT-treatment in diabetic rats showed opposite gene expression changes in the cases of 19 genes associated with diabetic cardiomyopathy. In healthy hearts, MVT-treatment resulted in cardiac gene expression changes mostly related to immune response (e.g. complement factor B; complement component 4a; interferon regulatory factor 7; hepcidin). CONCLUSIONS: MVT-treatment improved diagnostic markers of diabetes. This is the first demonstration that MVT-treatment significantly alters cardiac gene expression profile in both control and diabetic rats. Our results and further studies exploring the mechanistic role of individual genes may contribute to the prevention or diagnosis of cardiac complications in diabetes