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Compound Concentration (compound + concentration)
Selected AbstractsCatalysis of intumescent flame retardancy of polypropylene by metallic compounds,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2003Menachem Lewin Abstract Divalent and multivalent metallic compounds catalyze the flame retardancy performance of intumescent systems based on ammonium polyphosphate (APP) and pentaerythritol (petol) in poly(propylene) (PP). The catalytic effect is shown by increases in the oxygen index (OI) and UL-94 ratings. The effect is exerted by small concentrations of the metallic compounds in the range of 0.1,2.5 wt% of the compositions. The effect increases with the concentration of the catalyst until a maximum is reached. At higher concentrations of the catalyst a decrease in the flame retardancy parameters is observed, accompanied in several cases by a degradation and discoloration of the composition. The catalyst replaces melamine in intumescent systems. Catalytic effectiveness is defined and calculated for a number of compounds. Thermogravimetric parameters, such as initial decomposition temperature, temperature of the transition point and residue-after-transitions (RAT) change in parallel with the catalytic effect of the metal compound concentration. Metal compounds investigated include oxides, acetates, acetyl acetonates, borates and sulfates of Mn, Zn, Mg, Al, Ca, Ba,,V, Co, Ni, Cu, Mo, Zr, and Cr. Mechanistic considerations on the activity of the catalysts are presented. Copyright © 2003 John Wiley & Sons, Ltd. [source] Accurate analysis of taurine, anserine, carnosine and free amino acids in a cattle muscle biopsy sampleANIMAL SCIENCE JOURNAL, Issue 3 2010Mai IMANARI ABSTRACT We have established an analysis method for some free amino acids (FAAs), as well as taurine (Tau), anserine (Ans) and carnosine (Car), in a fresh biopsy sample from cattle muscle. A series of model biopsy samples, corresponding to the mixtures of lean meat, fat and connective tissue, was prepared and showed high correlation coefficients between the compound concentration and the 3-methylhistidine (3-MeHis) content derived from hydrolysis of the biopsy sample (r = 0.74,0.95, P < 0.01). Interference from blood contamination could not be neglected, because the concentration of some FAAs in blood was comparable to that in muscle. However, it was possible to control the contamination of Tau, Ans, Car, glutamic acid, glutamine, asparatic acid and alanine to less than 5.0% when the blood contamination was controlled to less than 23%. These results suggest the necessity of measuring 3-MeHis as an index of lean meat and hemoglobin as an index of blood contamination when compounds in muscle biopsy samples are evaluated. We have carried out a series of these analyses using one biopsy sample and reveal differences in Tau, Ans, Car and some FAAs in beef muscle after different feeding regimes. [source] Absolute rate constants for the gas-phase ozonolysis of isoprene and methylbutenolINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 3 2004N. Klawatsch-Carrasco The reactions of the biogenic organic compounds isoprene and 2-methyl-3-buten-2-ol (MBO) with ozone have been investigated under controlled conditions for pressure (atmospheric pressure) and temperature (293 ± 2 K), using FTIR spectrometry. CO was added to scavenge hydroxyl radical formation during the ozonolysis experiments. Reaction rate constants were determined by absolute rate technique, by measuring both ozone and the organic compound concentrations. The measured values were k1 = (1.19 ± 0.09) × 10,17 cm3 molecule,1 s,1 for the reaction between ozone and isoprene and k2 = (8.3 ± 1.0) × 10,18 cm3 molecule,1 s,1 for the reaction between ozone and MBO. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 152,156 2004 [source] The influence of rotary valve distribution systems on the energetic efficiency of regenerative thermal oxidizers (RTO)INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2008Mario Amelio Abstract On,off valve systems, commonly used in regenerative thermal oxidizer (RTO) plants, generate, during the opening time, a mass flow rate (MFR) which is constant. On the contrary, rotary valve systems, which are increasingly adopted in RTO plants, are characterized by variable MFR profiles. In this work, the energy requirements of two RTO systems, equipped with on,off or rotary valves, were determined using a home-developed numerical code. Energy performances were evaluated by calculating the thermal efficiency and pressure drop within structured or random packed bed RTO systems, at the same mean MFR. The results demonstrated that thermal efficiency was only moderately influenced by the valve system, and is slightly lower for the RTO with on,off valve. On the other hand, the study revealed that energy requirements of all RTO systems were basically unaffected by cycle duration, allowing valve rotational velocity to be freely set to maximize for other technical requirements. On the contrary, pressure drop was greatly influenced by the valve type and increased as variability in MFR function augmented. Moreover, the type of regenerator, structured or random packed bed, affected differently the total energy requirements (basically pumping energy plus auxiliary fuel). Energy requirements of structured and random regenerators were comparable only when volatile organic compounds concentration was lower than typical values encountered in the industrial practise. In other cases, structured regenerators RTO were more competitive. Finally, structured regenerators are usually the best choice when rotating valve distribution systems are adopted. Copyright © 2007 John Wiley & Sons, Ltd. [source] Particle Size Control of Nanocrystalline Anatase TiO2 Synthesized by Hydrolysis of Titanyl Organic CompoundsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 12 2008X.-Q. Chen Abstract The global nanocrystalline anatase TiO2 particle can be obtained by hydrolysis of titanyl organic compounds. Its particle size is mostly influenced by the titanyl organic compounds' concentration, nitric acid (HNO3) concentration, reaction time and temperature, and especially the HNO3 concentration. The formation of nanocrystalline TiO2 with bigger size can be accelerated by a higher temperature, thick solution of reactant (titanyl organic compounds), and HNO3. Vice versa, in order to gain smaller particles, such as 6 nm, the reaction conditions should be set at a thin reactant solution, low temperature, and low HNO3 concentration. The reason lies in the hydrolyzing mechanism of titanyl organic compounds, which is strongly influenced by the temperature and pH. [source] | ||||||||||