1,721,664 research outputs found
HRMAS NMR spectroscopy applications in agriculture
Full text linkThe relatively recent and advanced high-resolution magic angle spinning (HRMAS) NMR technique enables the direct application of NMR spectroscopy to semi-solid and gel-like samples. It combines the advantages of both solid- and liquid-state NMR by allowing to concomitantly measure intact and non-manipulated samples. Based on both 1D and 2D homo- and heteronuclear NMR spectra, HRMAS evaluates the composition of fresh semi-solid samples with a similar resolution as that of classical liquid-state NMR techniques. The enhanced spectral quality still obtained for semi-solid samples is mainly due to the MAS system, whose rapid spinning and sample orientation minimize the anisotropic processes that prevent the acquisition of meaningful NMR spectra for non-liquid materials. Moreover, HRMAS allows us to use edited pulse sequences which, especially in the case of biological tissues or agrofood products, may provide a simultaneous information on polar and non-polar components without the need of preliminary sample extraction. Additionally, this technique may differentiate molecular species according to their degree of mobility in hydrated matrices. The evident versatile potential of the HRMAS NMR makes this technique particularly useful for life science molecular studies. Despite the focus of HRMAS has been greatly devoted on clinical biomedicine, materials chemistry, and metabolomics, there are already enough studies that show useful applications on agricultural issues. This report reviews the latest representative studies that employ HRMAS NMR on systems related to agricultural chemistry, requiring the characterization and dynamics of soil components, plant tissues, agrofood products, and in vivo organisms
Physical-chemical characteristics of lignins separated from biomasses for second-generation ethanol
No full textLignin was extracted by two extraction methods from two biomasses for energy (Mischantus and Giant Reed) and a lignocellulosic material resulting from a microbial treatment of giant reed. One method of extraction involved the use of H2SO4 (SA), providing a highly aromatic water-insoluble material, while a second method employed H2O2 at alkaline pH (Ox), resulting in a water-soluble lignin. Extraction yields were related to the total Klason lignin measured for the three materials. We compared the physical-chemical features of the isolated lignins, by employing solid-state nuclear magnetic resonance spectroscopy (13C-CPMAS spectra and derived T1ρH relaxation times), thermogravimetric analyses, infrared spectrometry and high performance size exclusion chromatography (HPSEC). We found that lignin separated by the Ox method owned a more mobile molecular conformation, and was largely more water-soluble and fragmented than the lignin obtained by the SA treatment. In line with T1ρH-NMR and thermogravimetric results, the HPSEC of Ox lignins showed nominal molecular weights less than 3kDa, indicating well depolymerized materials. Such low-molecular weight and fragmented lignin obtained from biomasses for energy may become useful for application of recycled products in agriculture and in green chemistry reactions, thereby promoting an increase in the economic sustainability of biorefineries. © 2014 Elsevier Ltd
Fuzzy logic based optimal power flow management in Hybrid Electric Vehicles
No full textParallel Hybrid Electric Vehicle powertrain (PHEV), combining an electric motor with an auxiliary power unit, improves vehicle performance and fuel economy, reducing the effects of private cars on air quality in cities. These advantages can be enhanced by using a dedicated control strategy to identify the optimal power flow distribution at each instant of time in the main powerdrive sources as a function of the state of the powerdrive components and the actual driving conditions. In this connection the literature analysis has evidenced as the research efforts in the field of PHEV optimal power flow management should be oriented not only to develop precise and robust control strategies that can improve the vehicle performances, but also to lower the required computational resources making the solution strategy suitable with the vehicle dynamics and allowing, moreover, a cost effective hardware implementation. To develop this complex activity, fuzzy logic (FL) was used. As demonstrated by the simulation studies developed, FL enables the optimal power flow management problem to be solved by handling its intrinsic non-linearity using rules, membership functions, and the inference process. This results in improved performance, simpler implementation, and reduced design costs compared with rigorous mathematics based approaches
Reduced activity of β-glucosidase resulting from host-guest interactions with dissolved fulvic acids as revealed by NMR spectroscopy
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The molecular dynamics of soil humus as a function of tillage.
No full textSoil degradation processes due to intensified agriculture may be counteracted by an extended knowledge on soil humus dynamics at molecular level. Here, we show that the molecular composition of the soil Humeome changes substantially after 1 and 3 years of conventional tillage under maize cropping. Application of Humeomics sequential chemical fractionation not only separated from soil more than twice the organic carbon extracted by traditional methods, but also enabled to identify 10 times more molecular structures using GC–MS and high-resolution ESI-Orbitrap-MS. The fine molecular description of the soil Humeome revealed a decrease of soil organic matter (SOM) hydrophobic protection with prolonged tillage and a potential loss of small nitrogen-rich compounds. We showed for the first time an abundance of heterocyclic nitrogen compounds that are persistent in SOM due to a covalent binding to soil iron. The formation of organo-Fe complexes appeared not only as a major mechanism of molecular stabilization of SOC but also as an adsorption substrate for other nitrogen-rich soil components. The detailed molecular insight of SOM composition reached by Humeomics may become the key to develop new technologies for the control of soil carbon
Quantitative Evaluation of Noncovalent Interactions between Glyphosate and Dissolved Humic Substances by NMR Spectroscopy
No full textInteractions of glyphosate (N-phosphonomethylglycine) herbicide (GLY) with soluble fulvic acids (FM) and humic acids (HAs) at pH 5.2 and 7 were studied by H-1 and P-31 NMR spectroscopy. Increasing concentrations of soluble humic matter determined broadening and chemical shift drifts of proton and phosphorus GLY signals, thereby indicating the occurrence of weak interactions between GLY and humic superstructures. Binding was larger for FM and pH 5.2 than for HAs and pH 7, thus suggesting formation of hydrogen bonds between GLY carboxyl and phosphonate groups and protonated oxygen functions in humic matter. Changes in relaxation and correlation times of H-1 and P-31 signals and saturation transfer difference NMR experiments confirmed the noncovalent nature of GLY humic interactions. Diffusion-ordered NMR spectra allowed calculation of the glyphosate fraction bound to humic superstructures and association constants (K-a) and Gibbs free energies of transfer for GLY humic complex formation at both pH values. These values showed that noncovalent interactions occurred most effectively with FM and at pH 5.2. Our findings indicated that glyphosate may spontaneously and significantly bind to soluble humic matter by noncovalent interactions at slightly acidic pH and, thus, potentially pollute natural water bodies by moving through soil profiles in complexes with dissolved humus
Modelli di analisi per un management consapevole di istituzioni culturali complesse
No full textIn this paper we start one of the simplest forms of the quantitative statistical analysis known in literature as bivariate analysis. Based upon the cluster analysis as well as a principal component analysis for some quite standard models, we apply these tecniques in order to deeply analyze some political management strategies mainly related to the distinctive features of some important cultural institutions. More precisely, we point out some key features which can be taken into account for rationalizing the costs and improving the efficiency. Our results could be efficiently used in order to better planning the action of private or public corporations both national or international.
A special analysis is deserved for the choice of the models needed for the statistical elaboration of the data mainly based upon the core and topic activities of each instiution. Nowadays our methods are experimental in the essence
NMR-based metabolomics of water-buffalo milk after conventional or biological feeding
Full text linkAbstract Background Biological farming in dairy production is often advocated as one of the most virtuous solutions to the environmental problems of conventional farming while improving the sustainability of production and cattle welfare. However, it is still under debate whether the conversion from conventional to biological farming has an influence on milk composition. In addition, the possible frauds related to biological dairy products call for analytical tools enabling the authentication of products quality and consumers protection. The aim of this work was to determine the composition of milk produced by water-buffaloes and to identify the specific metabolic profiles discriminating a biological from a conventional feeding diet. Methods Liquid-state 1H, 13C, and 31P nuclear magnetic resonance (NMR) spectroscopies were used to study milk samples which were supplied during a 2-year-long experimentation by a single dairy farm and sampled from conventionally and biologically fed buffaloes (CFM and BFM, respectively). For each milk sample, we obtained NMR spectra of both raw milk and milk cream fractions comprising neutral lipids and phospholipids. Results The elaboration of multinuclear spectroscopic NMR results by the principal component analysis (PCA) enabled the identification of diagnostic differences in the milk composition between CFM and BFM samples. In particular, BFM were characterized by larger content of unsaturated lipids and phosphatidylcholine. Our findings confirmed that the conversion from a conventional to biological feeding regime influenced the buffalo milk composition, with possible implications for sensorial and nutritional properties of dairy products. Finally, the analytical methodology of NMR spectroscopy shown here may be considered as a useful tool to assess the quality and the authenticity of biological milk
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