0000000000149739
AUTHOR
Salvatore Bubici
Applicability of solid state fast field cycling NMR relaxometry in understanding relaxation properties of leaves and leaf-litters
Abstract Inversion recovery high field solid state (SS) 1H NMR spectroscopy and fast field cycling (FFC) NMR relaxometry have been applied on dried leaves and leaf-litters from a reafforestated area in central Sicily (Italy) in order to evaluate relaxation properties in both slow ( 1 ≪ ω 0 2 τ C 2 ) and fast ( 1 ≫ ω 0 2 τ C 2 ) motion regimes. Namely, SS 1H NMR spectroscopy (i.e. slow motion regime conditions) revealed that two relaxation components (a fast and a slow one) can be identified in all the leaves and leaf-litter samples. The fast component was assigned to small sized plant metabolites, whereas the slow one was attributed to slowly tumbling macropolymeric molecules. FFC NMR relax…
Nature of water-biochar interface interactions
A poplar biochar obtained by an industrial gasification process was saturated with water and analyzed using fast field cycling (FFC) NMR relaxometry in a temperature range between 299 and 353 K. Results revealed that the longitudinal relaxation rate increased with the increment of the temperature. This behavior was consistent with that already observed for paramagnetic inorganic porous media for which two different relaxation mechanisms can be accounted for: outer- and inner-sphere mechanisms. The former is due to water diffusing from the closest approach distance to infinity, whereas the second is due to water interacting by nonconventional H-bonds to the porous surface of the solid materi…
Solid-state 1H-NMR relaxation properties of the fruit of a wild relative of eggplant at different proton Larmor frequencies
1H longitudinal relaxation time profiles (T1) at different proton Larmor frequencies were registered for a solid state plant tissue by using fast field cycling (FFC) nuclear magnetic resonance (NMR) spectroscopy. T1 distributions were obtained and the curves deconvoluted in order to differentiate among the different T1 components. Among the components, two were assigned to hydrophobic (e.g. fatty acids) and hydrophilic (e.g. saccharides) molecular systems, whereas the remaining others were attributed to bulk and bound water. This paper showed for the first time solid state FFC-NMR spectroscopy applied to plant tissue, and revealed that relaxometry is a very promising technique for studying …
Dissolution mechanism of crystalline cellulose in H3PO4 as assessed by high-field NMR spectroscopy and Fast Field Cycling NMR relaxometry
Many processes have been proposed to produce glucose as a substrate for bacterial fermentation to obtain bioethanol. Among others, cellulose degradation appears as the most convenient way to achieve reliable amounts of glucose units. In fact, cellulose is the most widespread biopolymer, and it is considered also as a renewable resource. Due to extended intra- and interchain hydrogen bonds that provide a very efficient packing structure, however, cellulose is also a very stable polymer, the degradation of which is not easily achievable. In the past decade, researchers enhanced cellulose reactivity by increasing its solubility in many solvents, among which concentrated phosphoric acid (H(3)PO…
Evaluation of the surface affinity of water in three biochars using fast field cycling NMR relaxometry
Many soil functions depend on the interaction of water with soil. The affinity of water for soils can be altered by applying soil amendments like stone meal, manure, or biochar (a carbonaceous material obtained by pyrolysis of biomasses). In fact, the addition of hydrophobic biochar to soil may increase soil repellency, reduce water-adsorbing capacity, inhibit microbial activity, alter soil filter, buffer, storage, and transformation functions. For this reason, it is of paramount importance to monitor water affinity for biochar surface (also referred to as ‘wettability’) in order to better address its applications in soil systems. In this study, we propose the use of fast field cycling NMR …
Dynamics of pistachio oils by proton nuclear magnetic resonance relaxtion dispersion
A number of pistachio oils were selected in order to test the efficacy of nuclear magnetic resonance relaxation dispersion (NMRD) technique in the evaluation of differences among oils (1) obtained from seeds subjected to different thermal desiccation processes, (2) retrieved from seeds belonging to the same cultivar grown in different geographical areas and (3) produced by using seed cultivars sampled in the same geographical region. NMRD measures relaxation rate values which are related to the dynamics of the chemical components of complex food systems. Results not only allowed to relate kinematic viscosity to relaxometry parameters but also were successful in the differentiation among the…