Manganese is an element of great importance in the life cycle of plants and animals. For example, it plays an essential role as an activator of various enzymatic systems such as isoenzymes of superoxide dismutase. Freshwater Unionidae concentrate relatively large amounts of manganese in their tissues, but little is known about the physiological role of this metal. The aim of this research is to acquire a better knowledge of the role of manganese in molluscs which accumulate large amounts of this metal and in those with low manganese concentrations. As manganese is one of the metals present in the superoxide molecule, the possible relationship between manganese concentration in the soft tissues of molluscs and the antioxidant capacity of the metal can usefully be tested. To this end two species of molluscs were analysed: Unio pictorum mancus (Lamellibranchia, Unionidae), which is very rich in manganese, and Viviparus ater (Gastropoda, Prosobranchia) which has a low manganese content. The adults of both species were analysed for manganese concentration by ICP, and for antioxidant capacity as RAC (Relative Antioxidant Capacity) by a superoxide dismutase method. The results clearly demonstrate the active role played by manganese against free radicals and consequently the important role of the metal in protecting Unio against oxidative stress. The low concentration of manganese in Viviparus may be the result of the effective excretion of this metal, as was found for ruthenium
Antioxidant and radical-scavenging properties are alleged to form the basis of the therapeutic properties attributed to the papaya and papaya-based food and drug integrators that have recently appeared on the market. In the present research a biosensor-based method was used to determine the antioxidant capacity of papaya fruit as is, that of several food and drug integrators, and lastly of pure papain alone. Results are compared using a reference spectrofluorimetric method and two other spectrophotometric methods. In addition pro-oxidant properties of the same samples were also checked using two colorimetric methods
Background and methodsSeveral standard powdered black pigments were characterized by means of thermogravimetry TG-DTG and allied techniques. These pigments were used to make standard plaster frescoes at this purpose prepared. The latter ones were subjected to Raman and reflectance analysis. The results obtained, together with TG data, were chemometrically processed and used to identify an analogous standard fresco fabricated by an unknown commercial black pigment, obtaining excellent results.ResultsThe same colorimetric and reflectometric techniques, coupled with suitable chemometric techniques, were then successfully used to identify the type of black pigment present in an ancient roman fresco of the Imperial Age (30 B.C.).ConclusionTG-DTG resulted useful techniques to autenticate powdered black pigments.Colorimetry and Raman, but also the only colorimetry, were useful to identify an ancient black pigment in situ.
Using a cellulosic material dating method recently proposed by three of the authors of the present article further applications to real samples are discussed. In the first instance, to wood samples, that is, to a type of sample for which the method was specifically developed but with the samples differing widely in age, and then to textile or paper samples. Of course in the latter two cases the results obtained are still quite preliminary, above all because of the difficulty of procuring certainly dated samples of this type.
BackgroundThe possibility of applying a novel chemometric approach which could allow the differentiation of marble samples, all from different quarries located in the Mediterranean basin and frequently used in ancient times for artistic purposes, was investigated. By suggesting tentative or allowing to rule out unlikely attributions, this kind of differentiation could, indeed, be of valuable support to restorers and other professionals in the field of cultural heritage.Experimental data were obtained only using thermal analytical techniques: Thermogravimetry (TG), Derivative Thermogravimetry (DTG) and Differential Thermal Analysis (DTA).ResultsThe extraction of kinetic parameters from the curves obtained using these thermal analytical techniques allowed Activation Energy values to be evaluated together with the logarithm of the Arrhenius pre-exponential factor of the main TG-DTG process.The main data thus obtained after subsequent chemometric evaluation (using Principal Components Analysis) have already proved useful in the identification the original quarry of a small number of archaeological marble finds.ConclusionOne of the most evident advantages of the thermoanalytical – chemometric approach adopted seems to be that it allows the certain identification of an unknown find composed of a marble known to be present among the reference samples considered, that is, contained in the reference file. On the other hand with equal certainty it prevents the occurrence of erroneous or highly uncertain identification if the find being tested does not belong to the reference file considered.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.