Search results for "13C"

Solid state 13C-NMR methodology for the cellulose composition studies of the shells of Prunus dulcis and their derived cellulosic materials.

2020

Lignocellulosic fibers and microcellulose have been obtained by simple alkaline treatment from softwood al- mond shells. In particular, the Prunus dulcis Miller (D.A.) Webb. was considered as a agro industrial waste largely available in southern Italy. The materials before and after purification have been characterized by 13C CPMAS NMR spectroscopy methodology. A proper data analysis provided the relative composition of lignin and holo- cellulose at each purification step and the results were compared with thermogravimetric analysis and FT-IR. To value the possibility of using this material in a circular economy framework, the fibrous cellulosic material was used to manufacture a handmade c…

Sedimentary record of anthropogenic chemical and organic pollution in a Mediterranean coastal area (Gulf of Palermo, Italy).

2009

The relatively high influx of unregulated industrial and domestic effluents has progressively degraded the Palermo coastal environment in NW Sicily. To evaluate the poorly known effects of these inputs on the Palermo Gulf, three sediment box-cores were collected along a transect perpendicular to the coast, in front of the Oreto river mouth, in water depths of 20—750 m. The samples, dated by 210Pb and 137Cs, were analysed for concentration of major/trace elements, total polycyclic aromatic hydrocarbon (PAH), total organic carbon (TOC) and for organic carbon and nitrogen isotopic compositions. Total organic carbon concentrations show relatively high values (0.4—2.9%), with a decreasing seawar…

Isotopically (δ13C and δ18O) heavy volcanic plumes from Central Andean volcanoes: a field study

2017

International audience; Stable isotopes of carbon and oxygen in volcanic gases are key tracers of volatile transfer between Earth's interior and atmosphere. Although important, these data are available for few volcanoes because they have traditionally been difficult to obtain and are usually measured on gas samples collected from fumaroles. We present new field measurements of bulk plume composition and stable isotopes (δ13CCO2 and δ18OH2O+CO2) carried out at three northern Chilean volcanoes using MultiGAS and isotope ratio infrared spectroscopy. Carbon and oxygen in magmatic gas plumes of Lastarria and Isluga volcanoes have δ13C in CO2 of +0.76‰ to +0.77‰ (VPDB), similar to slab carbonate;…

Influence of biotic and abiotic factors on soil organic matter dynamics assessed by the biogeochemical characterisation of soluble organic matter

2014

Soils are the greatest reservoir of C on the continents, and organic matter mineralisation bymicrobial activity represents the major part of the CO2 emitted by terrestrial ecosystems.In this work, we studied water-extractable organic matter (WEOM), which corresponds to themore reactive fraction of soil organic matter (SOM). Our objectives were (i) to identify therelationships of WEOM dynamics with bacterial communities, and with soil physico-chemicalparameters; (ii) to provide a precise chemical characterisation of WEOM.There is a strong link between SOM solubility and the structure of bacterial communities, andan erosion of their diversity has an impact on SOM and WEOM dynamics, and leads …

DFT calculation of NMR delta(Cd-113) in cadmium complexes

2016

We have tested several DFT protocols, at the non-relativistic and relativistic ZORA (scalar and spin–orbit) levels, for the calculation of the 113Cd chemical shifts, δ(113Cd), for a number of cadmium complexes accounting for both different local coordination environments on the metal center, involving N, O and S ligands, and different geometrical arrangements. Moreover, suitable models as reference compounds for δ(113Cd) evaluation have been set up in order to propose a complete computational approach to calculate δ(113Cd) for cadmium complexes. Inclusion of relativistic corrections did not lead to any sensible improvement in the quality of results and, in this context, non-relativistic met…

Surfaces of minimal degree of tame representation type and mutations of Cohen–Macaulay modules

2017

We provide two examples of smooth projective surfaces of tame CM type, by showing that any parameter space of isomorphism classes of indecomposable ACM bundles with fixed rank and determinant on a rational quartic scroll in projective 5-space is either a single point or a projective line. For surfaces of minimal degree and wild CM type, we classify rigid Ulrich bundles as Fibonacci extensions. For the rational normal scrolls S(2,3) and S(3,3), a complete classification of rigid ACM bundles is given in terms of the action of the braid group in three strands.

Short term adaptive response of symbiotic N2 fixation in pea to root pruning of half the root system, linked to the availability of carbon assimilates

2014

Symbiotic N fixation of legumes is very sensitive to environmental stresses, like pea pests damaging nodulated roots. However, the impact on their N uptake capacity and plant growth has not been studied so far.We analyzed the adaptive response symbiotic N2 fixation and plant growth of pea wild type Frisson and hypernodulating mutants P64, P118 and P121 mutated respectively on genes SYM28, SYM29 and NOD3 to root pruning of half the root system at the end of the vegetative stage. The adaptive responses of pea: cv. Frisson and 3 of its hypernodulating mutants were compared under varying carbon supplies from photosynthesis.At 380 ppm, mutant P118 showed the lowest decrease of the specific activ…

Les phénols de la lignine et le 13C, traceurs de l'origine des matières organiques du sol

2001

Abstract In spodosols of Gascony (France), conversion of maritime pine stands into maize cropping leads to an incorporation of maize organic matter, which changed the isotopic (δ13C) and phenolic signature in A and L horizons of soil. Hydrolysis of phenol lignin in forests and cultivated soils showed the predominance of vanillic units under forest and the early but moderate incorporation of cinnamic acids. Incorporation of syringic units appeared higher, related to a large maize production of stable syringic phenols. Syringic units represented a long-term marker of maize inputs in soils, whereas vanillic units revealed the degradation of forest organic matter.

Réponses adaptatives du Pois protéagineux à une perturbation de la fixation symbiotique d'azote en relation avec le métabolisme carboné

2013

Variations du stockage et de la dynamique de la matière organique en fonction de l'utilisation des sols dans les savanes du Rift éthiopien.

2007

13 pages; International audience