Search results for "libration"
showing 10 items of 901 documents
Evaluation of the interelemental effect in X-ray fluorescence analysis by the total addition method
1992
An algorithm for quantifying interelemental effects in X-ray fluorescence techniques is developed. By applying an addition process, the ratio between the mass absorption coefficients of the analyte and the unknown sample (μi*/μs*) is calculated to correct the fluorescence intensity of the element to be determined and linearize the I-c calibration plot. This coefficient can be calculated graphically and numerically. The method is applied to the determination of tin in lead alloys with good results over wide concentration ranges.
Permian-Cenozoic deep-water carbonate rocks of the Southern Tethyan Domain. The case of Central Sicily
2016
We present an integrated stratigraphy of the outcropping and buried Permian-Cenozoic deep-water carbonate successions, forming some of the tectonic units mostly buried beneath the Late Neogene sedimentary cover in the fold and thrust belt of Central Sicily. Three main successions, pertaining to the well known Lercara, Imerese and Sicanian domains, have been reconstructed on the basis of a detailed facies analysis, seismostratigraphic interpretation, bio -stratigraphy (mostly based on palynological data) and comparison between outcropping and subsurface deep-water sediments. The main results reveal a continuous sedimentation of the deep-water Southern Tethyan Sicilian succession since the Pe…
Fluorometric determination of chemically available lysine: adaptation, validation and application to different milk products.
2004
A spectrophotometric method based on the reaction between available lysine and ortho-phthaldialdehyde (OPA) was adapted and validated for fluorometric determination of the chemically available lysine contents in milk matrices (UHT and conventional in-bottle sterilized cow milk, milk-based infant formulas and infant formula ingredients). The values of the analytical parameters show its usefulness as a routine method (linearity, r = 0.9992; detection limit, 0.0066 mg/mL assay; accuracy, 99-108%; precision, intra-day 2.1-5.9% and inter-day 3.5 10.2%). No statistically significant differences (p < 0.05) were found between the values obtained with the adapted method and those obtained applying t…
Evolution of emerging Fusarium mycotoxins contents throughout the shelf-life period of food
2014
which is cooked by steaming. It has been historically eaten in North African countries but nowadays its consumption is widely extended all around the world. As a cereal-based food, semolina is highly susceptible to contamination by mycotoxin-producing fungi. The presented procedure involves a modified QuEChERSbased extraction of 24 mycotoxins (15-ADON, 3-ADON, AFLAB1, AFLAB2, AFLAG1, AFLAG2, BEA, DON, DAS, ENA, ENA1, ENB, ENB1, FB1, FB2, FB3, FUSX, HT-2, NEO, NIV, OTA, STG, T2, ZEA) produced by Aspergillus, Penicillum and Fusarium fungi. The validation was performed by analyzing recovery samples at three different spiked concentrations with four replicates (n=4) at each concentration. Recov…
Liquid chromatographic determination of toxigenic secondary metabolites produced by Fusarium strains.
2002
Various liquid chromatographic methods used in the analysis of mycotoxins (zearalenone, trichothecenes and fumonisins) produced by Fusarium species were compared in this work. The results demonstrate the suitability of modern clean-up procedures employing multifunctional MycoSep and immunoaffinity columns although these methods are more expensive than conventional methodologies for clean-up. HPLC with both fluorescence and photodiode array detection is a suitable technique for the analysis of toxic secondary metabolites produced by Fusarium species; different derivatisation strategies have been studied to improve the sensitivity of the technique because of the low concentration of these met…
Diffuse soil gas emissions of gaseous elemental mercury (GEM) from hydrothermal-volcanic systems: An innovative approach by using the static closed-c…
2016
This study was aimed to test a new methodological approach to carry out measurements of gaseous elemental mercury (GEM) diffusively emitted from soils in hydrothermal-volcanic environments. This method was based on the use of a static closed-chamber (SCC) in combination with a Lumex® RA-915M analyzer that provides GEM measurements in a wide range of concentrations (from 2 to 50,000 ng m-3). Gas samples were collected at fixed time intervals from the SCC positioned on the ground (time-series samples). The Lumex® inlet port was equipped with a three-way Teflon valve allowing the free entrance of air through a carbon trap, in order to: (i) prevent disturbance to the Lumex® operative flow rate …
Quantification of pulmonary blood flow (PBF): validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with H(2)15O positron emi…
2009
Validation of quantification of pulmonary blood flow (PBF) with dynamic, contrast-enhanced MRI is still missing. A possible reason certainly lies in difficulties based on the nonlinear dependence of signal intensity (SI) from contrast agent (CA) concentration. Both aspects were addressed in this study. Nine healthy pigs were examined by first-pass perfusion MRI using gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and HO positron emission tomography (PET) imaging. Calculations of hemodynamic parameters were based on a one-compartment model (MR) and a two-compartment model (PET). Simulations showed a significant error when assuming a linear relation between MR SI and CA dose in the …
DNA quantification approach by GE-ICP-SFMS and complementary total phosphorus determination by ICP-SFMS
2006
Quantification of DNA is still a great challenge for scientists in many fields. Here, we present the on-line coupling of gel electrophoresis (GE) and inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) for quantitative purposes. GE conditions are chosen for optimised separations depending on the target analyte composition in terms of DNA chain length. In particular, agarose concentrations are varied in the range 0.6–2.2%, which corresponds to a separation range of DNA from 100 base pairs (bp) to genomic DNA (approximately 3 Mbp). Separated DNA compounds are directly transported at a flow rate of 100 μL min−1 to a Micromist nebuliser which is followed by ICP-SFMS with 31P de…
Determination of molecular mass, Stokes' radius, frictional coefficient and isomer-type of non-denatured proteins by time-dependent pore gradient gel…
1988
Molecular mass, Stoke's radius, frictional coefficient and isomer-type of non-denatured proteins can be obtained by time-dependent gradient gel electrophoresis by evaluating the resulting data using a two-step mathematical procedure. Provided a histochemical staining procedure is available to locate the position of an enzyme in the gel, crude cell extracts can be used for estimating their molecular size properties. The computation of molecular properties of non-denatured proteins is demonstrated for isozymes of aspartate aminotransferase (EC 2.6.1.1), peroxidase (EC 1.11.1.42) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) from current-year needles of spruce. The resulting data as well…
Determination of molecular weights and Stokes' radii of non-denatured proteins by polyacrylamide gradient gel electrophoresis. 2. Determination of th…
1982
Under certain conditions in polyacrylamide gradient gel electrophoresis (PAGGE), a linear correlation between the logarithm of the size of calibration proteins (log MW or log Rs) and the square root of their migration distance (√D) can be observed; slope and intercept of the calibration curve depend on the duration of electrophoresis; linearity, however, is maintained over a wide range (4-60 h, 200 V) (Rothe and Purkhanbaba, Electrophoresis 1982, 3, 33–42.) Using this method the reaction of plant isozyme systems penetrating a linear polyacrylamide (PAA) gradient gel was investigated: lactate dehydrogenase (LDH) from potato tubers behaves similarly to animal calibration proteins. The enzyme …