1,710 research outputs found
Analytical pyrolysis and thermal analysis to chemically characterise bitumen from Italian geological deposits and Neolithic stone tools
No full textThe chemical study of bitumen from stone tools from Italian Neolithic sites was carried out using analytical pyrolysis-based techniques, EGA-MS (evolved gas analysis mass spectrometry) and DSPy-GC/MS (double shot pyrolysis-gas chromatography/mass spectrometry). The study was mainly aimed at demonstrating the suitability of analytical pyrolysis for studying archaeological bitumen and for obtaining information regarding its origin. EGA-MS was employed to obtain information on the thermal complexity, that is the set of thermal properties and behaviours, of the samples and on their thermal degradation areas and DSPy-GC/MS along with Principal Component Analysis (PCA) were tested for biomarker analysis to assess bitumen source in archaeological objects. Geological bituminous rocks from Central-Southern Italy were selected and used as reference materials to both optimize experimental parameters and to support data interpretation for archaeological samples. Geological samples were also preliminary characterised by thermogravimetric analysis coupled with FTIR spectroscopy (TG-FTIR) under nitrogen and by TG analysis under oxygen to quantify their relative content of organic and inorganic species. The combination of thermal analysis and analytical pyrolysis-based techniques allowed us to quantify the organic content of the bitumen samples and to obtain information on both soluble and insoluble organic fractions. In addition, the proposed approach highlighted the main degradative patterns and the main differences among samples coming from different geographical areas as well as differences between geological and archaeological bitumen. Finally, DSPy-GC/MS associated with PCA proved to be successful in assessing the bitumen source in archaeological objects by the detection of terpanes, distinctive biomarkers
Rectore Academiae Salanae Magnificentissimo Serenissimo Principe Ac Domino Dn. Johanne Wilhelmo Duce Saxoniae, Iuliaci, Cliviae Ac Montium, &c. &c. Loco Exercitii Academici Theses Philologicas
No full textRECTORE ACADEMIAE SALANAE MAGNIFICENTISSIMO SERENISSIMO PRINCIPE AC DOMINO DN. JOHANNE WILHELMO DUCE SAXONIAE, IULIACI, CLIVIAE AC MONTIUM, &C. &C. LOCO EXERCITII ACADEMICI THESES PHILOLOGICAS
Rectore Academiae Salanae Magnificentissimo Serenissimo Principe Ac Domino Dn. Johanne Wilhelmo Duce Saxoniae, Iuliaci, Cliviae Ac Montium, &c. &c. Loco Exercitii Academici Theses Philologicas ([1]r)
Titelseite ([1]r)
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Text ([2]r
Isothermal calorimetry protocols to monitor the shelf life and aftermarket follow-up of fresh cut vegetables
No full textProtocols and guidelines were assessed in order to apply isothermal calorimetry as a complementary/alternative method to monitoring, during the shelf life and the microbial growth/metabolism in commercial fresh cut vegetables with random initial microbial population. Moreover, the endogenous microbial population was used as a biosensor to check the modifications occurred during long storage for aftermarket characterization in the frame of vegetable waste treatments. Validation was obtained following ready-to-use carrots highlighting the effects of the different exposed surfaces (cylinders, sticks and a`-la-julienne cut) on the overall spoiling process during shelf life and green salad stored up to 14 days with regard to the aftermarket characterization
Analysis of phenological behaviour of some mediterranean Shrub species in responses to warming and drought conditions
No full textA phenological behavior of Mediterranean species growing in a Mediterranean-type climate was described by developing a phenological scale. The sensitivity of some Mediterranean species to climate manipulations was evaluated. Climate manipulations were conducted on a Mediterranean macchia ecosystem that include sclerophyll species. The increase of daily minimum temperature of air and soil observed at 20 cm height and at 10 cm depth in the warming treatment was approximately equal to 0.5°C relative to control
Studies of Equilibria Between Amphiphilic Derivatives Of Salycilic Acid and Transition Metal Ions
No full textVULCAN: a European field scale manipulation project to assess the vulnerability of shrubland ecosystems under climatic changes
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Thermodynamics of Aqueous Solutions of Dodecyldimethylethylammonium Bromide
No full textThe thermodynamic properties of the aqueous solutions of dodecyldimethylethylammonium bromide (DEDAB) were determined as a function of concentration by means of direct methods. Dilution enthalpies at 298 and 313 K, densities and sound velocities at 298 K were measured, allowing the determination of apparent and partial molar enthalpies, volumes, heat capacities and compressibilities. Changes in thermodynamic quantities upon micellization were derived using a pseudo-phase transition approach. These data allow for the determination of the effect of the –CH2– group, when added to the polar head of alkyltrimethylammonium bromides. The properties mainly affected by this addition are the enthalpies and, as a consequence, the entropies. The lowering of the charge density on the quaternary nitrogen due to the inductive effect of the ethyl group, greater than that of the methyl one, raises the plateau value of apparent and molar enthalpy by a quantity similar to that due to the removing of a methylene group from the hydrophobic chain. This effect does not play a great role in the value of the cmc (i.e. on the free energy of micelle formation), since the small decrease in cmc of DEDAB compared to DTAB reflects the increase in the overall hydrophobicity of the molecule. Volumes of DEDAB are greater than those of DTAB by about 15 cm3 mol−1, both at infinite dilution and at micellar phase, a value in agreement with that generally accepted for a methylene group. The trends of apparent molar heat capacities and compressibilities vs m are the same as for DTAB: in fact, these quantities are related to the number of water molecules involved in the hydrophobic processes in solution, not very greatly affected by the substitution of a methyl group by an ethyl one on the polar head. In summary, this substitution affects to a significant extent the first derivatives of the free energy, but does not affect the second derivatives
Thermodynamics of the Equilibria Between Some 2-(Methylpyridyl)Benz-X-Azoles and Transition Metal Ions
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