Search results for "fractionation"
showing 10 items of 332 documents
Oxidation, efflux, and isotopic fractionation of methane during autumnal turnover in a polyhumic, boreal lake
2007
[1] We studied the oxidation and efflux of methane (CH4) in a small, polyhumic lake, Mekkojarvi (southern Finland), during 6 weeks in autumn when the stability of the water mass first weakened, temporarily restabilized, and finally mixed completely. During the summer stratification period, CH4 had accumulated in the anoxic hypolimnion to high concentrations (>150 mmol m−3). Gradual mixing of the water column during the autumn allowed access to both oxygen and CH4 by aerobic methane-oxidizing bacteria (MOB) deeper in the water column. Thus the bulk (∼83–88%) of the CH4 accumulated in the hypolimnion was subsequently consumed by MOB while only 12–17% was lost from the lake to the atmosphere a…
The behaviour of REEs in Thailand's Mae Klong estuary: Suggestions from the Y/Ho ratios and lanthanide tetrad effects
2007
Abstract The concentrations of Rare Earth Elements and yttrium (REY) were measured in dissolved phase, in suspended particulate matter (SPM) and in sediments in seven sampling stations in the Mae Klong estuarine system (Inner Thailand Gulf) in order to study their behaviour and distribution pattern. The analysed samples generally show high Rare Earth Element (REE) content in the dissolved phase, with high Medium Rare Earth Elements (MREEs) and Y enrichments in the shale-normalized pattern (versus PAAS). These chemical features are interpreted in terms of direct influences of weathering processes of REE-rich minerals (e.g., phosphates), which abundantly out-crop in the Mae Klong watershed. T…
Isolation of Cholinergic Synaptic Vesicles from the Myenteric Plexus of Guinea-Pig Small Intestine
1980
The acetylcholine-rich myenteric plexus-longitudinal muscle preparation of the guinea-pig small intestine has been subjected to subcellular fractionation using modifications of both classical methods and that originally devised for bulk isolation of cholinergic synaptic vesicles from the electromotor nerve terminals of Torpedo marmorata by means of density gradient centrifugation in a zonal rotor. The latter method gave a vesicle fraction with the highest acetylcholine content so far recorded for a mammalian particulate fraction, 30.9 +/- S.E.M. 1.8 (5) nmol of acetylcholine . mg of protein-1. Electron-microscopical examination showed that it consisted of a homogeneous preparation of vesicl…
Active Degassing of Deeply Sourced Fluids in Central Europe: New Evidences From a Geochemical Study in Serbia
2021
We report on the results of an extensive geochemical survey of fluids released in the Vardar zone (central-western Serbia), a mega-suture zone at the boundary between Eurasia and Africa plates. Thirty-one bubbling gas samples are investigated for their chemical and isotopic compositions (He, C, Ar) and cluster into three distinct groups (CO2-dominated, N2-dominated, and CH4-dominated) based on the dominant gas species. The measured He isotope ratios range from 0.08 to 1.19 Ra (where Ra is the atmospheric ratio), and reveal for the first time the presence of a minor (<20%) but detectable regional mantle-derived component in Serbia. δ13C values range from −20.2‰ to −0.1‰ (versus PDB), with…
Tumor lactate content predicts for response to fractionated irradiation of human squamous cell carcinomas in nude mice
2006
Abstract Background and purpose The present study was performed to test the hypothesis that lactate accumulation correlates with the radioresistance of malignant tumors due to the radical scavenging capacity of lactate or metabolic intermediates of glycolysis, such as pyruvate. Materials and methods Five human head and neck squamous cell carcinoma cell lines (HNSCCs) xenografted in nude mice were treated with a clinically relevant irradiation protocol with 30 fractions within 6 weeks. The radiation dose necessary to locally control 50% of the tumors (TCD 50 ) ranged from 47.4 to 129.8Gy. Concentrations of glucose, lactate, and ATP in viable tumor regions as potential indicators of glycolyti…
Clumped isotope analysis of carbonates: comparison of two different acid digestion techniques
2013
RATIONALE The kinetic nature of the phosphoric acid digestion reaction enables clumped isotope analysis of carbonates using gas source isotope ratio mass spectrometry (IRMS). In most laboratories acid digestions are performed at 25°C in sealed vessels or at 90°C in a common acid bath. Here we show that different Δ47 results are obtained depending on the digestion technique employed. METHODS Several replicates of a biogenic aragonite and NBS 19 were reacted with 104% H3PO4 in sealed vessels at 25°C and at 90°C using a common acid bath. The sample size varied between 4 mg and 14 mg. Purification methods that are standard for clumped isotope analyses were applied to the evolved CO2 before meas…
Aqueous enzymatic process assisted by microwave extraction of oil from yellow horn (Xanthoceras sorbifolia Bunge.) seed kernels and its quality evalu…
2013
Abstract In this study, aqueous enzymatic process (AEP) assisted by microwave extraction (ME) of oil from yellow horn ( Xanthoceras sorbifolia Bunge.) seed kernel was investigated. Central composite design (CCD) and response surface methodology (RSM) were used to optimise an enzyme cocktail (cellulase, hemicellulase, pectinase) for AEP. The main factors of ME were also studied. A maximal oil extraction yield of 55.8% was achieved under optimal conditions. Moreover, scanning electron microscope (SEM) was applied to characterise the extraction process. Analysing chemical composition of the extracted oil by GC–MS showed that the content of unsaturated fatty acids by this emerging method (91.18…
Improved resolution power of electrophoretic fractionation of DNA using a voltage gradient up and down application
2004
The improved resolution power of electrophoretic fractionation of DNA in a wide range of molecular masses is demonstrated using an "up and down" application of voltage gradient gel electrophoresis (VGGE). This application also allows separation of different DNA fragments which are poorly fractionated in conventional electrophoresis.
Dosimetric effect of respiratory motion on planned dose in whole-breast volumetric modulated arc therapy using moderate and ultra-hypofractionation.
2021
Abstract Background and purpose The interplay effect of respiratory motion on the planned dose in free-breathing right-sided whole-breast irradiation (WBI) were studied by simulating hypofractionated VMAT treatment courses. Materials and methods Ten patients with phase-triggered 4D-CT images were included in the study. VMAT plans targeting the right breast were created retrospectively with moderately hypofractionated (40.05 Gy in 15 fractions of 2.67 Gy) and ultra-hypofractionated (26 Gy 5 fractions of 5.2 Gy) schemes. 3D-CRT plans were generated as a reference. All plans were divided into respiratory phase-specific plans and calculated in the corresponding phase images. Fraction-specific d…
Synthesis and assembly of virus-like particles of human papillomaviruses type 6 and type 16 in fission yeast Schizosaccharomyces pombe.
1995
AbstractWe have synthesized capsid proteins of human papillomavirus types 6 (HPV 6) and 16 (HPV 16) in fission yeast Schizosaccharomyces pombe and produced virus-like particles (VLP). The capsid proteins were localized in the nucleus by indirect immunofluorescence and cell fractionation analyses. The VLP were produced in both yeast clones synthesizing L1 alone and L1/L2 and purified by sulfato-cellulofine chromatography. Electron microscopic examination showed that these VLP were similar in structure to native HPV particles. Two HPV 16 L1 variants (16 B27L1 and 16 T3L1), isolated from benign cervical samples, produced many more (68- and 14-fold) VLP than the prototype L1 (16 PL1) derived fr…