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Concentration Effects (concentration + effects)
Selected AbstractsTemperature and Impurity Concentration Effects on Degradation of Nickel/Yttria-stabilised Zirconia Anode in PH3 -Containing Coal SyngasFUEL CELLS, Issue 1 2010M. Zhi Abstract Degradation of the Ni/yttria-stabilised zirconia (YSZ) anode of the solid oxide fuel cell has been evaluated in the coal syngas containing different PH3 concentrations in the temperature range from 750 to 900,°C. Thermodynamic equilibrium calculations show that PH3 in the coal syngas gas is converted mostly to P2O3 at 750,900,°C. The phosphorous impurity reacts with the Ni-YSZ anode to form phosphates. The P-impurity poisoning leads to the deactivation of the Ni catalyst and to the reduction in the electronic conductivity of the anode. The impurity poisoning effect on the anode is exacerbated by increase in the temperature and/or the PH3 concentration. [source] Whey protein isolate coating and concentration effects on egg shelf lifeJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2005Cengiz Caner Abstract The influences of three different concentrations (6, 12 and 18%) of whey protein isolate (WPI) coatings on shelf-life enhancements of the fresh egg quality (weight loss, pH, Haugh unit, yolk index and colors) and the shelf life were evaluated at room temperature. All coated eggs showed lower weight loss than uncoated eggs. Less weight loss (2.46 for 12% WPI and 2.38 for 18% WPI) was observed in WPI-coated eggs. Haugh units (HU) indicated that coated eggs remained in grade ,A' during 3 weeks storage period, whereas uncoated (UC) changed from grade ,A' to ,B' after 1 week of storage. The HU and yolk-index (YI) values of all WPI-coated eggs were significantly higher than those of UC. Among the coated eggs, there were no significant differences in HU, but 12 and 18% WPI coated had higher YI than WPI 6% coated and UC. The albumen pH of the UC eggs was significantly higher than that of coated eggs. Yolk lightness (L*) and (b*); shell (a*) and (b*) of coated eggs were not different from UC after 4 weeks. Performance of WPI coatings depended on the concentration up to 12% but not between 12 and 18%. Results also indicated that WPI coatings served as protective barrier for shelf life of the eggs. Copyright © 2005 Society of Chemical Industry [source] In vitro and in vivo pharmacodynamic properties of the fluoroquinolone ibafloxacinJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2002M. Coulet The pharmacodynamic properties of a new veterinary fluoroquinolone antimicrobial agent, ibafloxacin, were evaluated. Minimal inhibitory concentrations (MIC), time-kill kinetics, postantibiotic effect (PAE) and postantibiotic subminimal inhibitory concentration effects (PA-SME) were determined against pathogenic canine Gram-negative and Gram-positive bacterial isolates from dermal, respiratory and urinary tract infections. The synergistic interactions between ibafloxacin and its main metabolite, 8-hydroxy-ibafloxacin were investigated. Finally, the efficacy of ibafloxacin was tested in in vivo canine infection models. Ibafloxacin had good activity against Pasteurella spp., Escherichia coli, Klebsiella spp., Proteus spp. and Staphylococcus spp. (MIC90=0.5 µg/mL), moderate activity against Bordetella bronchiseptica, Enterobacter spp. and Enterococcus spp. (MIC50=4 µg/mL) and low activity against Pseudomonas spp. and Streptococcus spp. The time-killing analysis confirmed that ibafloxacin was bactericidal with a broad spectrum of activity. The PAE and PA-SME were between 0.7,2.13 and 1,11.5 h, respectively. Finally, studies in dog models of wound infection and cystitis confirmed the efficacy of once daily oral ibafloxacin at a dosage of 15 mg/kg. Additional studies are needed to better define the importance of AUC/MIC (AUIC) and Cmax/MIC ratios on the outcome of fluoroquinolone therapy in dogs. [source] Transmission Fluctuation Spectrometry in Concentrated Suspensions.PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 1 2005Part Three: Measurements Abstract The theory of transmission fluctuation spectrometry (TFS) was developed for particle size analysis in flowing particle suspensions, whereby the statistical transmission fluctuations are used to extract the particle size distribution (PSD) and particle concentration. In the previous parts of this publication high concentration effects on TFS were investigated theoretically and by simulation. This work presents a study on TFS measurements in concentrated suspensions. By introducing an empirical correction to include the high concentration effects from both the monolayer structure and particle overlapping in the inversion algorithm, it is possible to obtain the particle size distribution and particle concentration over broad ranges of particle sizes and concentrations. [source] Biocompatible nanoparticles trigger rapid bacteria clusteringBIOTECHNOLOGY PROGRESS, Issue 4 2009Mona Utne Larsen Abstract This study reveals an exciting phenomenon of stimulated bacteria clustering. Rapid aggregation and microbial arrest are shown to occur in Escherichia coli solutions of neutral pH when chitosan nanoparticles with positive zeta potential are added. Because chitosan nanoparticles can easily be dispersed in aqueous buffers, the rapid clustering phenomenon requires only minuscule nanoparticle concentrations and will be critical in developing new methods for extricating bacterial pathogens. This work establishes the dominant role of electrostatic attraction in bacteria-nanoparticle interactions by varying the nanoparticle zeta potential from highly positive to strongly negative values, and by exploring concentration effects. For strongly negative nanoparticles, no clusters form, while aggregates are small and loose at intermediate conditions. In addition, optical density measurements indicate that over 90% of the suspended bacteria flocculate within seconds of being mixed with chitosan nanoparticles of a highly positive surface charge. Finally, the nanoparticles are significantly more efficient as a clustering agent compared to an equal mass of molecular chitosan in solution, as the bacteria-nanoparticle clusters formed are substantially larger. The bacteria-nanoparticle aggregation effect demonstrated here promises a rapid separation method for aiding pathogen detection and for flocculation of bacteria in fermentation processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Monitoring Protein Interactions in the Living Cell Through the Fluorescence Decays of the Cyan Fluorescent ProteinCHEMPHYSCHEM, Issue 7 2006Regis Grailhe Dr. Abstract Using fluorescence lifetime microspectroscopy and imaging techniques, we have studied the fluorescence of cyan fluorescent protein (CFP) transiently expressed in HEK-293 cells, in the presence or absence of its fluorescence resonance energy transfer (FRET) partner, yellow fluorescent protein (YFP). When the two proteins are attached through a 27-amino-acid linker, a 33,% average efficiency of intramolecular energy transfer is accurately determined inside the cell. Additionally, we observe a systematic quenching of the CFP fluorescence with increasing levels of protein expression. This quenching cannot be accounted for by formation of the previously described dimer of GFP-related proteins, since its magnitude is unchanged when the fluorescent proteins carry the mutation A206K shown to dissociate this dimer in vitro. Even when the intracellular protein concentration largely exceeds the in vitro dissociation constant of the dimer, self-association remains undetectable, either between free proteins or intramolecularly within the CFP,YFP construct. Instead, the detailed concentration effects are satisfactorily accounted for by a model of intermolecular, concentration-dependent energy transfer, arising from molecular proximity and crowding. In the case of CFP alone, we suggest that self-quenching could result from a pseudo-homo FRET mechanism between different, spectrally shifted emissive forms of the protein. These phenomena require careful consideration in intracellular FRET studies. [source] Additive concentration effects on enantioselective separations in supercritical fluid chromatography,CHIRALITY, Issue 4 2003Karen W. Phinney Abstract Polar additive concentration effects in supercritical fluid chromatography were studied on chiral stationary phases having either a macrocyclic glycopeptide or a derivatized polysaccharide as the chiral selector. Two basic additives, isopropylamine and triethylamine, were incorporated into the methanol modifier at various concentrations and the effects on retention, selectivity, and resolution were monitored. Many of the analytes failed to elute from the macrocyclic glycopeptide stationary phase in the absence of an additive and the most noticeable effect of increasing additive concentration was a significant decrease in retention. On the derivatized polysaccharide stationary phase the additives had little effect on retention, but they did foster significant improvements in peak shape and resolution. Chirality 15:287,294, 2003. Published 2003 Wiley-Liss, Inc. [source] | ||||||||||