The Experts below are selected from a list of 32607 Experts worldwide ranked by ideXlab platform

L. Luo - One of the best experts on this subject based on the ideXlab platform.

  • phosphorus speciation and transformation in long term fertilized soil evidence from Chemical Fractionation and p k edge xanes spectroscopy
    Nutrient Cycling in Agroecosystems, 2017
    Co-Authors: L. Luo, Rebecca L Sanders, Satish Chandra Babu Myneni
    Abstract:

    Knowledge of speciation and transformation of phosphorus (P) in soil following high application rates of Chemical and organic fertilizers is essential for improving P management in Chinese agricultural ecosystems because P fertilizers have been increasingly overapplied in China. Phosphorus speciation of the soil in three long-term fertilization experiments established in 1990 was investigated jointly with a sequential Fractionation scheme and P K-edge X-ray absorption near edge structure (XANES) spectroscopy. Both Chemical Fractionation and XANES spectroscopy confirmed that P species in the topsoils (0–20 cm) were mainly composed of iron phosphate, calcium phosphate and organic P, regardless of soil pH and mineralogy. The continuous application of nitrogen, phosphorus and potassium fertilizers (NPK) had little effect on the distribution of P species in the topsoils compared with that in the control and 1990 baseline topsoils. In contrast, the application of NPK plus organic manures (MNPK) changed significantly the speciation distribution of P by increasing distinctly available P in the soil. The transportation and transformation of P species depended on soil properties including P levels, organic carbon concentrations and mineral types. The long-term application of MNPK facilitated the transportation of P into lower horizons and the accumulation of organic P in the soil. The XANES results provided spectroscopic support for the P species identified by the Fractionation scheme, and the combination of the two techniques provided complementary information on the speciation and transformation of P in soil.

  • sulphur speciation and availability in long term fertilized soil evidence from Chemical Fractionation and s k edge xanes spectroscopy
    European Journal of Soil Science, 2016
    Co-Authors: Shaobin Wang, Z. J. Chen, L. Luo
    Abstract:

    Knowledge of sulphur (S) speciation in soil following applications of Chemical and organic fertilizers is important for understanding the availability and fate of S in agricultural ecosystems. Sulphur speciation of the soil in three fields, which are part of the National Long-term Monitoring Network of Soil Fertility and Fertilizer Effects of China, was investigated with a combination of a wet-Chemical Fractionation scheme and S K-edge X-ray absorption near edge structure (XANES) spectroscopy. Treatments of the soil included no fertilizers (control), regular applications of nitrogen, phosphorus and potassium fertilizers (NPK), or of NPK plus organic manures (MNPK) since 1990. Soil samples were taken from the topsoil (0–20 cm) and subsoil (20–40 cm) horizons in 2011. Chemical Fractionation showed that available sulphate was the predominant inorganic S species in the Eutric Cambisol, whereas HCl-extractable sulphate was the main inorganic S species in the Haplic Phaeozem and Calcaric Cambisol. Organic S accounted for up to 77% of total S in all soil samples. Results from the Fractionation (inorganic S plus ester-S) and XANES analysis (oxidized S) were correlated (r = 0.585, P < 0.01), which confirmed the presence of HCl-extractable sulphate and the speciation of residual S in soil. Long-term application of organic manures facilitated significantly the accumulation of intermediate and reduced S species and increased total and organic S in the soil (P < 0.01). In contrast, the application of Chemical fertilizers (NPK) had little effect on the distribution of organic S species compared with the control. Atmospheric deposition was identified as an important source of S. The combination of Chemical Fractionation and XANES spectroscopy provided complementary information on the availability and speciation of S in soil. Highlights Availability and species of S are characterized with Chemical Fractionation and XANES spectroscopy. Insoluble sulphate is identified as an important form of S in the soil regardless of soil pH. Organic manure facilitates the accumulation of organic S in long-term fertilized soil. Atmospheric deposition contributes importantly to the input and cycling of S in soil.

  • Sulphur speciation and availability in long‐term fertilized soil: evidence from Chemical Fractionation and S K‐edge XANES spectroscopy
    European Journal of Soil Science, 2016
    Co-Authors: Shouyang Wang, Z. J. Chen, L. Luo
    Abstract:

    Knowledge of sulphur (S) speciation in soil following applications of Chemical and organic fertilizers is important for understanding the availability and fate of S in agricultural ecosystems. Sulphur speciation of the soil in three fields, which are part of the National Long-term Monitoring Network of Soil Fertility and Fertilizer Effects of China, was investigated with a combination of a wet-Chemical Fractionation scheme and S K-edge X-ray absorption near edge structure (XANES) spectroscopy. Treatments of the soil included no fertilizers (control), regular applications of nitrogen, phosphorus and potassium fertilizers (NPK), or of NPK plus organic manures (MNPK) since 1990. Soil samples were taken from the topsoil (0–20 cm) and subsoil (20–40 cm) horizons in 2011. Chemical Fractionation showed that available sulphate was the predominant inorganic S species in the Eutric Cambisol, whereas HCl-extractable sulphate was the main inorganic S species in the Haplic Phaeozem and Calcaric Cambisol. Organic S accounted for up to 77% of total S in all soil samples. Results from the Fractionation (inorganic S plus ester-S) and XANES analysis (oxidized S) were correlated (r = 0.585, P < 0.01), which confirmed the presence of HCl-extractable sulphate and the speciation of residual S in soil. Long-term application of organic manures facilitated significantly the accumulation of intermediate and reduced S species and increased total and organic S in the soil (P < 0.01). In contrast, the application of Chemical fertilizers (NPK) had little effect on the distribution of organic S species compared with the control. Atmospheric deposition was identified as an important source of S. The combination of Chemical Fractionation and XANES spectroscopy provided complementary information on the availability and speciation of S in soil. Highlights Availability and species of S are characterized with Chemical Fractionation and XANES spectroscopy. Insoluble sulphate is identified as an important form of S in the soil regardless of soil pH. Organic manure facilitates the accumulation of organic S in long-term fertilized soil. Atmospheric deposition contributes importantly to the input and cycling of S in soil.

Emmanuel G. Koukios - One of the best experts on this subject based on the ideXlab platform.

  • Optimizing multisteps mechanical-Chemical Fractionation of wheat straw components
    Industrial Crops and Products, 1998
    Co-Authors: M.g. Papatheofanous, Evaggeli Billa, D.p. Koullas, B Monties, Emmanuel G. Koukios
    Abstract:

    Abstract Wheat straw was refined into fibres, hemicellulosic sugars and lignin oligomers by means of a multi-stage Fractionation treatment: mechanical separation of the botanical components followed by one or two stage Chemical Fractionation process. Yellow winter wheat straw was initially separated into two fractions by milling in a Disc Mill: (a) chips, containing mostly internodes and (b) meal, consisting mainly of ground leaves and nodes. The internode fraction (63% of the whole straw) contained 8% more cellulose, 9% more lignin and 10% less ash compared with the unfractionated material. Disc mill Fractionation was particularly effective with respect to the separation of the non-lignocellulosic components, i.e. protein, extractives, etc. Wheat straw internodes as well as whole straw were treated with acidic or alkaline aqueous ethanol in one or two stages; two-stage treatment involved the introduction of a pretreatment step with dilute acid improving, both, the production of hemicellulose derived sugars, and the aqueous-ethanol delignification to follow. The fibre yield in the case of internode Chemical Fractionation was generally higher in comparison with the one of the whole straw. The fibrous Fractionation residues from internodes were in all cases enriched in cellulose compared with whole straw fibres. In spite of the higher initial lignin content of the internodes, delignification was more extensive than in the case of whole straw. Moreover, variations in the residual lignin composition were found, reflecting the intensity of the Chemical Fractionation process, as well as the origin of the raw material.

  • Optimizing multisteps mechanical-Chemical Fractionation of wheat straw components
    Industrial Crops and Products, 1998
    Co-Authors: M.g. Papatheofanous, Evaggeli Billa, D.p. Koullas, B Monties, Emmanuel G. Koukios
    Abstract:

    Wheat straw was refined into fibres, hemicellulosic sugars and lignin oligomers by means of a multi-stage Fractionation treatment: mechanical separation of the botanical components followed by one or two stage Chemical Fractionation process. Yellow winter wheat straw was initially separated into two fractions by milling in a Disc Mill: (a) chips, containing mostly internodes and (b) meal, consisting mainly of ground leaves and nodes. The internode fraction (63% of the whole straw) contained 8% more cellulose, 9% more lignin and 10% less ash compared with the unfractionated material. Disc mill Fractionation was particularly effective with respect to the separation of the non-lignocellulosic components, i.e. protein, extractives, etc. Wheat straw internodes as well as whole straw were treated with acidic or alkaline aqueous ethanol in one or two stages; two-stage treatment involved the introduction of a pretreatment step with dilute acid improving, both, the production of hemicellulose derived sugars, and the aqueous-ethanol delignification to follow. The fibre yield in the case of internode Chemical Fractionation was generally higher in comparison with the one of the whole straw. The fibrous Fractionation residues from internodes were in all cases enriched in cellulose compared with whole straw fibres. In spite of the higher initial lignin content of the internodes, delignification was more extensive than in the case of whole straw. Moreover, variations in the residual lignin composition were found, reflecting the intensity of the Chemical Fractionation process, as well as the origin of the raw material. (C) 1998 Elsevier Science B.V

Maja Welna - One of the best experts on this subject based on the ideXlab platform.

  • Direct ICP-OES multielement analysis of infused black and green teas and Chemical Fractionation of selected essential and non-essential elements prior to evaluation of their bioavailability and classification of teas by pattern recognition
    Arabian Journal of Chemistry, 2020
    Co-Authors: Pawel Pohl, Anna Szymczycha-madeja, Maja Welna
    Abstract:

    Abstract Operationally defined Chemical Fractionation of Al, Ba, Ca, Cu, Fe, Mg, Mn, Ni, Sr and Zn in infusions of loose leaf and bagged black and green teas was carried out. It was based on tandem-column solid phase extraction using reverse-phase and strong cation-exchange extraction tubes connected in series. Concentrations of elements in resultant infusions as well as column effluents and eluates were determined with the aid of inductively coupled plasma optical emission spectrometry and a newly developed simplified sample preparation procedure. It was established that information on separated Chemical fractions, particularly the fraction of residual species of elements, had better discrimination power than information about total concentrations of these elements. Differences in Chemical Fractionation patterns of elements in infusions of analyzed four types of tea led to simple classification of different black and green teas by principal component analysis and linear discriminant analysis.

  • New Green Determination of Cu, Fe, Mn, and Zn in Beetroot Juices along with Their Chemical Fractionation by Solid-Phase Extraction.
    Molecules (Basel Switzerland), 2019
    Co-Authors: Pawel Pohl, Anna Szymczycha-madeja, Mateusz Pieprz, Anna Dzimitrowicz, Piotr Jamroz, Maja Welna
    Abstract:

    A new simple and rapid method for the determination of the total concentrations of Cu, Fe, Mn, and Zn in beetroot juices by flame atomic absorption spectrometry was developed and validated. The method included a very simple sample preparation, i.e., the two-fold dilution and acidification of the samples with HNO3 to 1 mol·L−1 and provided the precision within 2–3% and the trueness better than 6%. The method was applied for the rapid screening analysis of the different commercially available beetroot juices. The Chemical Fractionation of Cu, Fe, Mn, and Zn was also proposed by the two-column solid-phase extraction with the reversed-phase and cation exchange tubes. It was revealed that Cu, Fe, Mn, and Zn were primarily in beetroot juices in the form of the organically bound forms, contributing to the distinguished hydrophobic and residual fractions. The sums of the mean contributions of both fractions were up to 98% (Cu, Fe, Zn) and 100% (Mn), pointing out that no labile nor unbound forms of the studied metals were present in the matrix of beetroot juices.

  • Simple ICP-OES based method for determination of selected elements in brewed ground and soluble coffees prior to evaluation of their intake and Chemical Fractionation.
    Food chemistry, 2018
    Co-Authors: Pawel Pohl, Anna Szymczycha-madeja, Maja Welna
    Abstract:

    Abstract A simple method of simultaneous determination of aluminum (Al), barium (Ba), calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), strontium (Sr) and zinc (Zn) in brews of ground and soluble coffees was proposed. It relied on acidification of brews with HNO 3 to 1.3 mol L −1 and their analysis by inductively coupled plasma optical emission spectrometry. Precision of 0.1–9% and detection limits from 0.07 ng mL −1 (Sr) to 3 ng mL −1 (Ni) were achieved. Trueness of the method was verified by comparison of results with those achieved with wet digestion and by the recovery study, and was better than 5%. Additionally, Chemical Fractionation by tandem solid phase extraction with reverse-phase and strong cation-exchange extraction tubes was carried out. Differences in Chemical Fractionation patterns, particularly the residual fraction, was useful for differentiation of ground and soluble coffees by analysis of variance, principle component analysis and hierarchical clustering analysis.

Pawel Pohl - One of the best experts on this subject based on the ideXlab platform.

  • Direct ICP-OES multielement analysis of infused black and green teas and Chemical Fractionation of selected essential and non-essential elements prior to evaluation of their bioavailability and classification of teas by pattern recognition
    Arabian Journal of Chemistry, 2020
    Co-Authors: Pawel Pohl, Anna Szymczycha-madeja, Maja Welna
    Abstract:

    Abstract Operationally defined Chemical Fractionation of Al, Ba, Ca, Cu, Fe, Mg, Mn, Ni, Sr and Zn in infusions of loose leaf and bagged black and green teas was carried out. It was based on tandem-column solid phase extraction using reverse-phase and strong cation-exchange extraction tubes connected in series. Concentrations of elements in resultant infusions as well as column effluents and eluates were determined with the aid of inductively coupled plasma optical emission spectrometry and a newly developed simplified sample preparation procedure. It was established that information on separated Chemical fractions, particularly the fraction of residual species of elements, had better discrimination power than information about total concentrations of these elements. Differences in Chemical Fractionation patterns of elements in infusions of analyzed four types of tea led to simple classification of different black and green teas by principal component analysis and linear discriminant analysis.

  • New Green Determination of Cu, Fe, Mn, and Zn in Beetroot Juices along with Their Chemical Fractionation by Solid-Phase Extraction.
    Molecules (Basel Switzerland), 2019
    Co-Authors: Pawel Pohl, Anna Szymczycha-madeja, Mateusz Pieprz, Anna Dzimitrowicz, Piotr Jamroz, Maja Welna
    Abstract:

    A new simple and rapid method for the determination of the total concentrations of Cu, Fe, Mn, and Zn in beetroot juices by flame atomic absorption spectrometry was developed and validated. The method included a very simple sample preparation, i.e., the two-fold dilution and acidification of the samples with HNO3 to 1 mol·L−1 and provided the precision within 2–3% and the trueness better than 6%. The method was applied for the rapid screening analysis of the different commercially available beetroot juices. The Chemical Fractionation of Cu, Fe, Mn, and Zn was also proposed by the two-column solid-phase extraction with the reversed-phase and cation exchange tubes. It was revealed that Cu, Fe, Mn, and Zn were primarily in beetroot juices in the form of the organically bound forms, contributing to the distinguished hydrophobic and residual fractions. The sums of the mean contributions of both fractions were up to 98% (Cu, Fe, Zn) and 100% (Mn), pointing out that no labile nor unbound forms of the studied metals were present in the matrix of beetroot juices.

  • Simple ICP-OES based method for determination of selected elements in brewed ground and soluble coffees prior to evaluation of their intake and Chemical Fractionation.
    Food chemistry, 2018
    Co-Authors: Pawel Pohl, Anna Szymczycha-madeja, Maja Welna
    Abstract:

    Abstract A simple method of simultaneous determination of aluminum (Al), barium (Ba), calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), strontium (Sr) and zinc (Zn) in brews of ground and soluble coffees was proposed. It relied on acidification of brews with HNO 3 to 1.3 mol L −1 and their analysis by inductively coupled plasma optical emission spectrometry. Precision of 0.1–9% and detection limits from 0.07 ng mL −1 (Sr) to 3 ng mL −1 (Ni) were achieved. Trueness of the method was verified by comparison of results with those achieved with wet digestion and by the recovery study, and was better than 5%. Additionally, Chemical Fractionation by tandem solid phase extraction with reverse-phase and strong cation-exchange extraction tubes was carried out. Differences in Chemical Fractionation patterns, particularly the residual fraction, was useful for differentiation of ground and soluble coffees by analysis of variance, principle component analysis and hierarchical clustering analysis.

  • simplified sample treatment for the determination of total concentrations and Chemical Fractionation forms of ca fe mg and mn in soluble coffees
    Food Chemistry, 2014
    Co-Authors: Pawel Pohl, Ewelina Stelmach, Anna Szymczychamadeja
    Abstract:

    A simpler, and faster than wet digestion, sample treatment was proposed prior to determination of total concentrations for selected macro- (Ca, Mg) and microelements (Fe, Mn) in soluble coffees by flame atomic absorption spectrometry. Samples were dissolved in water and acidified with HNO3. Precision was in the range 1-4% and accuracy was better than 2.5%. The method was used in analysis of 18 soluble coffees available on the Polish market. Chemical Fractionation patterns for Ca, Fe, Mg and Mn in soluble coffees, as consumed, using a two-column solid-phase extraction method, determined Ca, Mg and Mn were present predominantly as cations (80-93% of total content). This suggests these elements are likely to be highly bioaccessible.

R. M. Tripathi - One of the best experts on this subject based on the ideXlab platform.

  • Understanding the solid phase Chemical Fractionation of uranium in soil and effect of ageing
    Journal of hazardous materials, 2016
    Co-Authors: Sabyasachi Rout, Ajay Kumar, P. M. Ravi, R. M. Tripathi
    Abstract:

    The aim of the present work is to understand the solid phase Chemical Fractionation of Uranium (U) in soil and the mechanism involved. This study integrated batch experiments of U(VI) adsorption to soil, study of U in different soil fractions, ageing impact on Fractionation of U and spectroscopic investigation of adsorbed U(VI) using X-ray Photoelectron Spectroscopy (XPS). For the study three soils, pedogenically different (S1: Igneous, S2: Sedimentary and S3: Metamorphic) were amended with U(VI) and Chemical Fractionation of U was studied by sequential extraction after an interval of one month and 12 months. It was found that there occurs a significant rearrangement of U in different fractions with ageing and no correlation was observed between the U content in different fractions and the adsorbents of respective fractions such as soil organic matter (SOM), Fe/Mn oxides (hydroxides) carbonates, soil cation exchange capacity (CEC). XPS study revealed that surface enrichment of U mainly governed by the carbonate minerals and SOM, whereas bulk concentration was controlled by the oxides (hydroxides) of Si and Al. Occlusion of U-Fe-oxides (hydroxides) on silica was identified as an important mechanism for bulk enrichment (Increase in residual fraction) and depletion of U concentration in reducible fraction.