Search results for "EXTRACTION"
showing 10 items of 2072 documents
Determination of steady-state levels of oxidative DNA base modifications in mammalian cells by means of repair endonucleases
1997
The alkaline elution technique in combination with various repair endonucleases (Fpg protein, endonuclease III, exonuclease III, T4 endonuclease V) was used to quantify steady-state (background) levels of oxidative base modifications in various types of mammalian cells. In human lymphocytes the number of base modifications sensitive to Fpg protein, which include 8-hydroxyguanine, was 0.25 +/- 0.05 per 10(6) base pairs. Even lower levels (0.07 +/- 0.02 per 10(6) bp) were observed in HeLa cells. The numbers of sites sensitive to the other repair endonucleases were below the detection limit (0.05 per 10(6) bp). In a direct comparison, the background level of Fpg-sensitive modifications determi…
EXTRACTION OF BIOLOGICALLY ACTIVE COMPONENTS FROM FRESHWATER SAPROPEL
2019
Sapropel has been used for different purposes - in agriculture as fertilizer, in construction as building material, in cosmetic products, in balneology also in medicine and pharmaceuticals as bioactive component. Previously sapropel has been commonly used in raw form and there is no general accepted method or standard method for obtaining sapropel extract. However, most extraction methods follow the same path. Currently, there are few extraction methods using several extractants for obtaining bioactive components from raw sapropel. The most commonly used extractant is alkaline solution. When sapropel is subjected to alkaline environment, the humic and fulvic acids, together with some lipids…
UJI AKTIVITAS ANTIBAKTERI DAN SKRINING FITOKIMIA EKSTRAK HEKSANA, ETIL ASETAT DAN METANOL TUMBUHAN SURUHAN (Peperomia pellucida L. Kunth)
2020
Antibacterial activity test and screening of phytochemical of extract hexane, ethyl acetate and methanol have been carried out. The extraction of the P.pellucida plants was carried out by the maceration method in stages based on the polarity of the solvent. Analysis of chemical compounds done with phytochemical screening test. Based on the identification of chemical compounds by phytochemical screening, hexane and ethyl acetate extract has been detected only in the presence of flavonoid compounds with moderate categories. Methanol extract contains high-grade alkaloids and moderate flavonoid and tannin compounds. Antibacterial test using disffusion methods suggest that ethyl acetate and me…
Impact of ultrasound-assisted extraction and solvent composition on bioactive compounds and in vitro biological activities of thyme and rosemary
2020
Mediterranean herbs, specially thyme and rosemary, are important ingredients in food preparation and more recently have been studied as natural sources of bioactive compounds. This study aimed to study the effect of matrix (thyme vs. rosemary), and extraction protocol (conventional extraction vs. ultrasound assisted extraction) solvent composition (water vs. 50:50 ethanol:water solution) on the extraction of high value compounds (phenolic compounds, flavonoids and carotenoids) and also explore the antioxidant, antimicrobial (Listeria innocua, Staphylococcus aureus, and Salmonella enterica), probiotic (Lactobacillus casei and Bifidobacterium lactis), and anti-inflammatory activities. The phe…
Effects of solvent-free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the convention…
2008
The essential oil of Calamintha nepeta has been obtained by solvent-free microwave extraction (SFME) and by classical hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 38 compounds, constituting 97.6% of the oil, were identified in the oil obtained by SFME, whereas 46 compounds, representing 95.4% of the oil, were characterized in the HD oil. SFME-distilled oil is richer in lightly oxygenated monoterpenes (LOM) than HD oil. It also has a higher amount of sesquiterpenes and a lower quantity of hydrocarbon monoterpenes. HD oil seems to be affected by chemical changes more than SFME oil.
Structural modifications in an irradiated ethylene-vinyl alcohol copolymer
1982
Extraction experiments and calorimetric measurements have been performed, on a commercial ethylene-vinyl alcohol copolymer irradiated in the dose range 0–20 Mrad.
Recent Applications of Carbonaceous Nanosorbents in Solid Phase Extraction for the Determination of Pesticides in Food Samples
2018
This article covers recent trends of carbonaceous nanomaterial supported solid phase extraction for the liquid and gas chromatography analysis of pesticides in food samples. Several advanced carbonaceous nanosorbents have been reported over the previous decade for pesticide extraction, such as graphene derivatives modified by combination with silica, amines, polymers, and/or magnetic nanoparticles. The advances in this field have opened possibilities for using neat or modified carbon nanotubes or graphene-type sorbents for the pre-concentration of polar or nonpolar pesticides by solid phase extraction (SPE) or micro-SPE methods or to apply such nanomaterials for the removal of matrix compon…
Large Scale Fractionation of Macromolecules
2004
Access to sufficiently large amounts of material with adequate molecular and chemical uniformity from polydisperse natural products or synthetic materials has been a long-standing challenge to polymer scientists. We have developed a broadly applicable preparative fractionation method consisting of a special kind of continuous extraction removing the easier soluble components from the initial product. It is rendered possible by the use of spinning nozzles throught which a concentrated polymer solution is pressed into a liquid of tailored thermodynamic quality. The initially produced jets of the source phase disintegrate rapidly into minute droplets of typically 50 μm diameter. This efficient…
Pressure-induced formation of diblock copolymer "micelles" in supercritical fluids. A combined study by small angle scattering experiments and mean-f…
2004
We developed a simple time-dependent mean-field theory to describe the phase separation kinetics of either homopolymers or AB-diblock copolymers in supercritical (SC) fluids. The model, previously used to describe the phase behavior of AB-block copolymers under the assumption of strong solvent selectivity for just one copolymer chain, has been extended to study the kinetics of the phase separation process. Time resolved small angle x-ray scattering (TR-SAXS) measurements have been performed on different AB-diblock copolymers containing a perfluorinated chain and dissolved in SC-CO2. The data obtained over a wide range of pressure and temperature confirm our theoretical predictions. Particul…
Modern trends in solid phase extraction: New sorbent media
2016
Abstract Based on the recently published literature, this review provides an update of the most important features and application of formats and devices employed in solid phase extraction (SPE). Special attention was paid on new trapping media proposed in SPE prior the chromatography analysis, based on the use of nanostructured materials, including carbon nanomaterials, electrospun nanofibers, dendrimes and magnetic nanoparticles, molecular recognition sorbents, as aptamers, immunosorbents, molecular imprinted polymers, ion imprinting polymers, metal-organic frameworks and restricted access materials. Discussions on the present limitations as well as expected future trends of the new trapp…