Search results for "Complex Mixture"
showing 10 items of 826 documents
Characterisation of humic acids in fen peat
2020
Fens store significant amounts of organic matter and thus are of high importance from the perspective of the organic carbon biogeochemical cycle. Fen peat comprises moderately to highly decomposed higher plant remains with relatively high mineral matter content. Humic acids form the major part of fen peat organic matter; they are also the most refractory and recalcitrant natural substances to degradation, and thus they contain essential information regarding mire and peat development over large periods of time as well as the organic carbon biogeochemical cycle. Moreover, humic substances in fen peat are a prospective resource for applications in agriculture and other sectors. The aim of thi…
Carbon decomposition of the topsoils and soil fractions under forest and pasture in the western Brazilian Amazon basin, Rondonia
2000
The topsoils of two sites, comprising natural forest and 4- and 20-year-old pastures, respectively, were selected in Rondonia to evaluate the changes of soil organic matter due to pasture establishment. These changes were evaluated by measuring the proportions of the C and N associated with clay and silt fractions, and by the C decomposition (CD) rate of the whole topsoils and their size fractions. The topsoils studied had large proportions of C and N associated with fine fractions, especially with clay fractions. The CD rate of the silt fractions was higher than that of the clay fractions under the two forest topsoils and under the 20-year-old pasture. The CD rate of the silt fractions und…
Changes in cell wall pectin and pectinase activity in apple and tomato fruits duringPenicillium expansum infection
2006
Cell wall pectin degradation in apple and tomato fruit during infection by Penicillium expansum was investigated. In infected apple fruit, a significant decrease in the average molecular mass was observed in pectins extracted with CDTA and also in pectins extracted with Na2CO3. In tomato fruits, depolymerisation was also observed in both pectic fractions during infection, the major change being in the pectins extracted with Na2CO3. This pectin depolymerisation associated with P. expansum infection can be attributed to the action of pectinases; in apple fruit, a significant increase in polygalacturonase and pectin methylesterase was observed in infected fruits, although in tomato fruit the o…
The Influence of Biomass Ash on the Migration of Heavy Metals in the Flooded Soil Profile - Model Experiment
2014
Soils that have been exposed to fl ood waters can be heavily polluted by inorganic and organic compounds. They are mainly compounds which appear in dissolved or suspended form fl owing together with heavily laden fl oodwater, as well as compounds created as a result of reactions in the soil profi le, mostly due to anaerobic transformation of organic matter. Heavy metals brought with fl ood waters are absorbed by the soil and also washed out from fl ood sediments by precipitation when the fl ood recedes. This paper presents the results of research on the effects of fertilization with ash from incineration or pyrolysis of biomass on the migration process of heavy metals (Zn, Cu, Cr, Ni, Pb, C…
FTIR TENTATIVE CHARACTERIZATION OF HUMIC ACIDS EXTRACTED FROM ORGANIC MATERIALS
2001
Turkish humic acids, extracted from different materials, were characterized by their infrared spectra and by means of acidity measurements. The information obtained is of great interest to ascertain the nature and origin of humic acid samples.
Stratification in Drying Polymer–Polymer and Colloid–Polymer Mixtures
2017
Drying polymer-polymer and colloid-polymer mixtures were studied using Langevin dynamics computer simulations. Polymer-polymer mixtures vertically stratified into layers, with the shorter polymers enriched near the drying interface and the longer polymers pushed down toward the substrate. Colloid-polymer mixtures stratified into a polymer-on-top structure when the polymer radius of gyration was comparable to or smaller than the colloid diameter, and a colloid-on-top structure otherwise. We also developed a theoretical model for the drying mixtures based on dynamical density functional theory, which gave excellent quantitative agreement with the simulations for the polymer-polymer mixtures a…
Alkaloids from Rauwolfia serpentina cell cultures treated with ajmaline
1993
Abstract A group of new alkaloids, the raumaclines, and some related alkaloids were isolated from Rauwolfia serpentina cell suspensions fed with high levels of ajmaline; their structures were determined and syntheses developed providing an essential prerequisite to the further study of their biosynthesis at the enzymatic level.
Peat humic acid properties and factors influencing their variability in a temperate bog ecosystem
2013
Studies of the properties of soil organic matter are essential for understanding the humification reactions and soil diagenesis processes. The aim of this study is to analyse properties of peat and peat humic acids as well as factors influencing their variability. Humic acids isolated from an ombrotrophic bog peat profile were used as study objects. Relations among peat age, decomposition and humification degree, botanical composition, and properties of peat humic acids (elemental, functional composition, spectral characteristics) were studied. The variability of peat properties was found to be less significant than the differences in the properties of peat-forming living matter, which indi…
Characterization of Humic Acids from Raised Bog Peat
2014
Abstract Humic substances form most of the organic component of soil, peat and natural waters, but their structure and properties are very much dependent on the source. The aim of this study was to characterize humic acids from raised bog peat to evaluate the homogeneity of humic acids isolated from the bog bodies and to study peat humification impact on the properties of humic acids. Peat humic acids (HA) have an intermediate position between the living organic matter and coal organic matter, with their structure formed in a process where the relatively labile moieties (carbohydrates, amino acids, etc.) are destroyed, and thermodynamically more stable aromatic and polycyclic structures eme…
Characterization of Interaction Between Humic Acids and Buckminsterfullerene Using Flourescene Spectroscopy
2017
The interaction between buckminsterfullerene C60 and humic acids (HA) of different origins was compared using fluorescence spectroscopy as a function of pH, humic acid concentration, ionic strength. Binding constants between fullerene and humic acids were calculated. It can be suggested that the complexation was driven by hydrophobic interactions depending on the properties of the interacting compounds. Hydrophobic interaction model as indicated by linear Stern-Volmer plots and high Kd values is characterizing the interaction between buckminsterfullerene C60 and humic acids The results of this study support the development of an understanding of the fate of nanomaterials in the environment …