Search results for "layer"

Quantitative determination of moniliformin in vegetable foods and feeds

1984

A suitable and simple method for the quantitative determination of moniliformin in vegetable foods and feeds is described. The mycotoxin was extracted by Soxhlet extraction with methanol from mouldy maize, rice, rye, oats, wheat and barley samples. Moniliformin was determined by thin-layer chromatography (TLC) using N-methylbenzthiazolon-2-hydrazone (MBTH) as a new derivatization reagent for this mycotoxin. The moniliformin derivative was assayed at 518 nm. Quantification could be performed after calibration. A linear relationship between mycotoxin amount and peak area was found from 100 to 400 ng/spot. The detection limit is 75 ng/spot.

Die direkte quantitative auswertung von dünnschichtchromatogrammen durch remissions- und fluoreszenzmessungen

1971

Abstract Direct quantitative evaluation of thin-layer chromatograms by remission- and fluorescence measurements. Part 6. Determination of adrenaline, noradrenaline and dopamine from urine Adrenaline, noradrenalineand dopamine were separated from urine on aluminium oxide columns; after elution they were converted into ther O 3 ,O 4 ,N-triacetyl derivatives and separated using thin-layer chromatography. The triacetyl derivatives were in situ converted to fluorescing compounds using ethylene diamine and quantitatively estimated using the Chromatogram-Spectrophotometer (Carl Zeiss, Oberkochen). The advantage of this method over the conventional fluorometric determination of catecholamines in so…

Combining high performance thin layer chromatography with minispectrometer-fiber optic probe-coupled to smartphone for in place analysis: Lactose qua…

2021

ABSTRACT An in place colorimetric method has been proposed for estimation of the quantity of lactose in several matrix (milk, water effluents and surfaces). Analyzing the amount of this carbohydrate it can be control the product, the cleanliness of the parts of the dairy companies and it can avoid contamination of milk products produced there. This method combines the use of HPTLC for sugars separation with novel analytical devices as minispectrophotometer with fiber optic coupled to a smartphone. In order to measure the lactose a colorimetric reaction has been used. Variable volumes of samples or stock solutions were deposited in nano-silica gel layer, a mobile phase of acetonitrile:water:…

Detergent Properties Influence the Stability of the Glycophorin A Transmembrane Helix Dimer in Lysophosphatidylcholine Micelles

2012

AbstractDetergents might affect membrane protein structures by promoting intramolecular interactions that are different from those found in native membrane bilayers, and fine-tuning detergent properties can be crucial for obtaining structural information of intact and functional transmembrane proteins. To systematically investigate the influence of the detergent concentration and acyl-chain length on the stability of a transmembrane protein structure, the stability of the human glycophorin A transmembrane helix dimer has been analyzed in lyso-phosphatidylcholine micelles of different acyl-chain length. While our results indicate that the transmembrane protein is destabilized in detergents w…

XRF analysis to identify historical photographic processes: The case of some Interguglielmi Jr.’s images from the Palermo Municipal Archive

2017

Abstract In the early period, even though professional photographers worked with similar techniques and products, their artistic and commercial aims determined different choices and led them to follow different, often personal, recipes. For this reason, identification of the techniques through date and name of the photographer or through some visual features like colour, tonality and surface of the image layer, often needs further investigation to be proved. Chemical characterization, carried out in a non or micro destructive way, can be crucial to provide useful information about the original composition, degradation process, realization technique, in obtaining an indirect dating of the ph…

Simultaneous clean up of fish fat containing low levels of residues and separation of PCB from chlorinated pesticides by thin-layer chromatography

1974

Inhibition of skin inflammation in mice by diclofenac in vesicular carriers: Liposomes, ethosomes and PEVs

2013

Diclofenac-loaded phospholipid vesicles, namely conventional liposomes, ethosomes and PEVs (penetration enhancer-containing vesicles) were developed and their efficacy in TPA (phorbol ester) induced skin inflammation was examined. Vesicles were made from a cheap and unpurified mixture of phospholipids and diclofenac sodium; Transcutol P and propylene glycol were added to obtain PEVs, and ethanol to produce ethosomes. The structure and lamellar organization of the vesicle bilayer were investigated by transmission electron microscopy and small and wide angle X-ray scattering, as well as the main physico-chemical features. The formulations, along with a diclofenac solution and commercial Volta…

Two-dimensional electrical ordering in physisorbed monolayers

1990

Abstract Monolayers of polar molecules CF3H, CF3Cl and CF2Cl2 have been physisorbed on the graphite (001) surface and studied by X-ray diffraction and dielectric measurements. The temperature-coverage phase diagrams of the quasitwodimensional crystalline phases are presented. The structures of the paraelectric and the electrically ordered phases have been determined. The phase transitions are discussed.

X-ray diffraction study of CF3Cl monolayers adsorbed on graphite (001)

1988

X-ray diffraction experiments have been performed on mono- and submonolayers of CF3Cl physisorbed on the (001) surfaces of exfoliated graphite. Five quasi-twodimensional solid phases including the commensurate 2×2 phase, an electrically ordered phase and a disordered incommensurate phase have been observed. A phase diagram is proposed and the various phase transitions are discussed.

Synchrotron X-ray Diffraction and Reflection Studies of a Polymacromonomer Monolayer at the Air−Water Interface:  Transition from Aligned Single Mole…

2004

Monolayers of polymacromonomers with poly(vinyl)pyridine side chains of different lengths, polyPVP20.8 and polyPVP46.7, are studied at the air/water interface. Combination of reflection data and diffraction peaks allows the establishment of a structural model. In the expanded phase at pressures below approximately 15 mN/m, the side chains are adsorbed to the air/water interface, causing polymer backbone stretching and alignment of the single molecules. The in-plane peaks are due to the lateral electron density variation above and below the adsorption layer. The diameter of the flattened cylindrical molecules corresponds to twice the contour length of the side chains (25 and 12.5 nm, respect…