Combustion Kinetics of Biomass Materials in the Kinetic Regime

Wheat straw, willow from an energy plantation, and municipal sewage sludge were studied by thermogravimetry at linear and nonlinear heating programs in gas flows containing 4 and 20% oxygen. A kinetic scheme of successive devolatilization and char burnoff reactions was assumed. A distributed activation energy model (DAEM) was assumed for the devolatilization with a Gaussian distribution and a constant pre-exponential factor. The burnoff of the forming char was approximated by first-order kinetics with respect to the amount of char. The dependence of the reactions upon the oxygen concentration was described by power functions. This model gave a suitable description for the wheat straw and sewage sludge. An additional partial reaction with accelerating kinetics was needed for describing the oxidative cellulose pyrolysis in the willow sample. The evaluations were carried out by the method of least squares. 9-17 model parameters were determined from ten experiments for each sample. Good fit quality and reasonable kinetic parameters were obtained. Test evaluations revealed that the first-order kinetics, with respect to the amount of char is an adequate model; the assumptions of more complex char burnoff submodels did not led to notable improvements. The replacement of the DAEM devolatilization by simpler n-order kinetics gave inadequate performance. Earlier works with simpler models and linear temperature programs showed that the successive mechanism can be well-approximated by parallel reactions. Such approximations proved to be viable in the present case, too

MICAN, a new fluorophore for vital and non-vital staining of human cells

K

Effect of plant density on grain yield, yield components and agronomic traits of maize (Zea mays L.) hybrids

KAL

Magas inert tartalmú és biogázok tüzelési tulajdonságainak vizsgálata = Investigation of Combustion Properties of High Inert Gases and Biogases

A kutatási projekt első évében feltérképezésre kerülek főbb európai biogáz források. Egyik típus a biológiai bomlással előállított, vagy deponia gázok, ezek tipikus összetétele 60% CH4. A másik a termikus bontással előállított úgynevezett pirolízis gázok. A biomasszát elgázosíthatjuk anaerob úton, aerob úton levegővel, vagy tiszta oxigénnel. Az összehasonlító vizsgálatokat ezzel a négy típusgázzal és a referencia földgázzal végeztük. A GRI 3.0 mechanizmus segítségével modelleztük a kiválasztott gázok égése során kialakuló lángterjedési sebességeket és az adiabatikus lánghőmérsékleteket. Kialakítottuk a mérőrendszert vizsgálatokra. A Schlieren rendszer segítségével elkészül képek alapján meghatározzuk az szögeltérüléseket. A gázok égési folyamatiról CFD számításokat végeztünk, majd az eredményekből szintén számítással meghatároztuk az szögeltérüléseket. Így a CFD számítások ellenőrzésére is lehetőség van. Az elkészült mérőrendszernek másik eleme a lángspectrométer, segítségével mérhetők lángokban létrejövő különböző rövidéletű gyökök a lángsugárzás hullámhossz szerinti összetételének mérésével. A láng ionizáció egy adott térfogatban a vezetőképesség mérésével követhető, amely az égés során létrejövő rövidéletű gyökökre vezethető vissza. Ennek a lángon belüli vizsgálatára alakítottuk ki a lángionizációs mérőberendezésünket. A méréseket elvégeztük mind az öt gázzal, a mérési eredményekről internetes katalógust alakítottunk ki. | IIn beginig of this project the European biogas types and sources were determined. There are biogases which were made by biodegradation and deposit gases. The typical composition of these gases is: 60% CH4 and 40% CO2. And there are so called pyrolysis gases which were made by thermo degradation. Biomass can be gasified anaerobe or aerobe way with air or with oxygen. The comparative analysis was made with this four gas type and reference gas. The adiabatic flame temperature and laminar flame velocity of these gases was modelled by the GRI 3.0 mechanism. The measuring system was installed for the investigations. The angular deflections were determined from the Schlieren pictures. CFD calculations were made from the combustion process of these gases, and the angular deflections were determined from these calculations too, so CFD calculations can be validated. The other unit of the installed measuring system is the flame spectrophotometer. The radical composition of the flame can be determined by the flame emission spectroscopy at different condition of combustion. The flame ionisation is detectable by the measurement of the conductivity in a given volume, which is caused by the radicals in the flame. For the measurement of the flame ionisation the flame ionisation measuring system was installed. From the results was made a catalogue on the internet. Presently there are measurements with the aerobe pyrolysis gas and natural gas mixtures in gas engine

AAPH or Peroxynitrite-Induced Biorelevant Oxidation of Methyl Caffeate Yields a Potent Antitumor Metabolite

Hydroxycinnamic acids represent a versatile group of dietary plant antioxidants. Oxidation of methyl-p-coumarate (pcm) and methyl caffeate (cm) was previously found to yield potent antitumor metabolites. Here, we report the formation of potentially bioactive products of pcm and cm oxidized with peroxynitrite (ONOO¯), a biologically relevant reactive nitrogen species (RNS), or with α,α′-azodiisobutyramidine dihydrochloride (AAPH) as a chemical model for reactive oxygen species (ROS). A continuous flow system was developed to achieve reproducible in situ ONOO¯ formation. Reaction mixtures were tested for their cytotoxic effect on HeLa, SiHa, MCF-7 and MDA-MB-231 cells. The reaction of pcm with ONOO¯ produced two fragments, an o-nitrophenol derivative, and a new chlorinated compound. Bioactivity-guided isolation from the reaction mixture of cm with AAPH produced two dimerization products, including a dihydrobenzofuran lignan that exerted strong antitumor activity in vitro, and has potent in vivo antimetastatic activity which was previously reported. This compound was also detected from the reaction between cm and ONOO¯. Our results demonstrate the ROS/RNS dependent formation of chemically stable metabolites, including a potent antitumor agent (5), from hydroxycinnamic acids. This suggests that diversity-oriented synthesis using ROS/RNS to obtain oxidized antioxidant metabolite mixtures may serve as a valid natural product-based drug discovery strategy