Search results for "Concentration."
showing 10 items of 1849 documents
Magnetically enhancing the Seebeck coefficient in ferrofluids.
2019
The influence of the magnetic field on the Seebeck coefficient (Se) was investigated in dilute magnetic nanofluids (ferrofluids) composed of maghemite magnetic nanoparticles dispersed in dimethyl-sulfoxide (DMSO). A 25% increase in the Se value was found when the external magnetic field was applied perpendicularly to the temperature gradient, reminiscent of an increase in the Soret coefficient (ST, concentration gradient) observed in the same fluids. In-depth analysis of experimental data, however, revealed that different mechanisms are responsible for the observed magneto-thermoelectric and -thermodiffusive phenomena. Possible physical and physico-chemical origins leading to the enhancemen…
Anaerobic digestion of grass silage in batch leach bed processes for methane production.
2007
Abstract Anaerobic digestion of grass silage in batch leach bed reactors, with and without a second stage upflow anaerobic sludge blanket (UASB) reactor, was evaluated. Sixty six percent of the methane potential in grass was obtained within the 55 days solids retention time in the leach bed–UASB process without pH adjustment, whereas in the one-stage leach bed process 20% of the methane potential in grass was extracted. In two-stage operation, adjustment of the pH of influent to the leach bed reactor to 6 with HCl led to inhibition of both hydrolysis/acidogenesis and methanogenesis. In the leach bed–UASB process 39% of the carbohydrates and 58% of the acid soluble lignin were solubilised wi…
Effects of confinement on insulin amyloid fibrils formation.
2006
Insulin, a 51-residue protein universally used in diabetes treatment, is known to produce amyloid fibrils at high temperature and acidic conditions. As for other amyloidogenic proteins, the mechanisms leading to nucleation and growth of insulin fibrils are still poorly understood. We here report a study of the fibrillation process for insulin confined in a suitable polymeric hydrogel, with the aim of ascertain the effects of a reduced protein mobility on the various phases of the process. The results indicate that, with respect to standard aqueous solutions, the fibrillation process is considerably slowed down at moderately high concentrations and entirely suppressed at low concentration. M…
Shape transitions of giant liposomes induced by an anisotropic spontaneous curvature
2000
International audience; We explore how a magnetic field breaks the symmetry of an initially spherical giant liposome filled with a magnetic colloid. The condition of rotational symmetry along the field axis leads either to a prolate or to an oblate ellipsoid. We demonstrate that an electrostatic interaction between the nanoparticles and the membrane triggers the shape transition. PACS numbers: 75.
Finansinis stabilumas ir koncentracija: besivystančios Europos tyrimas
2016
Šiame straipsnyje tiriamas bankų sektoriaus koncentracijos poveikis finansiniam stabilumui naudojant 134 komercinių bankų iš 17 Vidurio ir Rytų Europos šalių 2007-2012 m. laikotarpio duomenis. Empirinio tyrimo rezultatai pabrėžia vadinamąją „koncentracijos trapumo“ hipotezę, parodydami, kad aukštas koncentracijos lygis bankų sektoriuje yra siejamas su didesne bankų, ypač mažesniųjų, įsipareigojimų neįvykdymo tikimybe. Taip pat parodoma, kad neigiamas koncentracijos poveikis gali būti sumažintas taikant griežtą priežiūros sistemą. Pirmiausia - griežtas oficialus bankų sektoriaus priežiūros įgaliojimas. Antra - skirtingi priimančiosios šalies ir buveinės šalies priežiūros įgaliojimai gali žym…
Seminal plasma biochemistry and spermatozoa characteristics of Atlantic cod (Gadus morhua L.) of wild and cultivated origin
2011
Abstract Our objectives were to compare spermatozoa activity, morphology, and seminal plasma (SP) biochemistry between wild and cultivated Atlantic cod ( Gadus morhua ). Swimming velocities of wild cod spermatozoa were significantly faster than those of cultivated males. Wild males had a significantly larger spermatozoa head area, perimeter, and length, while cultivated males had more circular heads. Total monounsaturated fatty acids and the ratio of n−3/n−6 were significantly higher in sperm from wild males, while total n−6 from cultivated males was significantly higher than the wild males. Significantly higher concentrations of the fatty acids C14:0, C16:1n−7, C18:4n−3, C20:1n−11, C20:1n−…
Treatment of columnaris disease of rainbow trout: low pH and salt as possible tools?
2005
The impact of salt and low pH on columnaris disease of fish was studied. Survival of Flavobacterium columnare after exposure to either 4% NaCl (pH 7.2) or pH 5.0, pH 4.86 or pH 4.6 for 15 min or 1 h was studied in vitro. All conditions significantly reduced the numbers of viable bacterial cells. The effects of salt (4 and 2%) and acidic baths (pH 4.6) were studied in 2 experiments in vivo with rainbow trout Oncorhynchus mykiss infected with F. columnare. Both salt and acidic baths failed to prevent fish mortality; the overall mortality reached 100% in all groups. However, according to survival analysis, the mortality rate was lower in fish treated with 4% salt baths compared to a control gr…
Flavonoids from Acacia pennata and their Cyclooxygenase (COX-1 and COX-2) Inhibitory Activities
2007
Two new flavonoids quercetin 4'-O-alpha-L-rhamnopyranosyl-3-O-beta-D-allopyranoside (1) and apigenin 6-C-[2''-O-(E)-feruloyl- beta-D-glucopyranosyl]-8-C-beta-glucopyranoside (2), along with the known isorhamnetin 3-O-alpha-L-rhamnopyranoside (3), kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (4), and isovitexin (5) were isolated from the leaves of Acacia pennata Willd. (Mimosaceae) and tested for their anti-inflammatory activity. Their structures were determined by 1D and 2D NMR and mass spectrometry. They were tested for an inhibitory effect on COX-1 and COX-2, showing 60-90% inhibition at 10(-4) g/mL and 5-14% inhibition at 10(-4) g/mL, respectively.
Simultaneous determination of four 5-hydroxy polymethoxyflavones by reversed-phase high performance liquid chromatography with electrochemical detect…
2009
Accumulating evidence has suggested the potential health-promoting effects of 5-hydroxy polymethoxyflavones (5-OH-PMFs) naturally existing in citrus genus. However, research efforts are hampered by the lack of reliable and sensitive methods for their determination in plant materials and biological samples. Using reversed-phase high performance liquid chromatography (HPLC) equipped with electrochemical (EC) detection, we have developed a fast and highly sensitive method for quantification of four 5-OH-PMFs, namely 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, 5-hydroxy-6,7,4'-trimethoxyflavone, and 5-hydroxy-6,7,8,4'-tetramethoxyflavone. The method wa…
Aircraft-based operation of an aerosol mass spectrometer: Measurements of tropospheric aerosol composition
2006
The Aerodyne quadrupole aerosol mass spectrometer was deployed on the Falcon twin jet research aircraft operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). This was the first deployment of an AMS in a jet aircraft. Aerosol mass concentration measurements in the troposphere up to altitudes of about 11 km were performed within two measurement flights on 12 and 14 May 2003 over southern Germany. Background aerosol data were gained up to 6 km, while aircraft exhaust aerosol was be sampled at higher altitudes on 14 May, indicating the presence of sulfuric acid and unburned hydrocarbons in the exhaust particles. The boundary layer aerosol on 12 May was found to be composed of 49% organic…