Multispectral analysis of miniature nuragic bronze flasks

Miniaturized bronze flasks represent a small portion of a wide metallurgical production that flourished in Sardinia (Italy) between the Final Bronze Age (FBA) and the Early Iron Age (EIA). They replicate a well-known and symbolic type of object, the pilgrims’ flask, common in all Europe and Mediterranean basin, and have but few archaeological parallels. For these reasons, their characterization can be considered important from an archaeological perspective. Three flasks, preserved at the Antiquarium Arborense museum (Oristano), were analyzed by X-Ray Fluorescence Spectroscopy (XRF) and Raman spectroscopy, integrated by multispectral images. The samples, coming from illegal excavations, posed two problems: establishing their authenticity and investigating the alloy composition of such particular objects. All specimens presented a widespread degradation in the outer surface: XRF and Raman spectroscopy indicated the presence of copper oxides, calcium and copper carbonates deposits. The abscence of Zn, a clear marker of forgeries, was not detected by XRF. In two of the flasks, an unusual Sn content above 20%, was detected. For FBA and EIA, especially regarding southern Europe, Sn was extremely rare, and was possibly used with caution. Further results are presented herein

Formation mechanisms and phase stability of solid-state grown cspbi3 perovskites

CsPbI3 inorganic perovskite is synthesized by a solvent-free, solid-state reaction, and its structural and optical properties can be deeply investigated using a multi-technique approach. X-ray Diffraction (XRD) and Raman measurements, optical absorption, steady-time and time-resolved luminescence, as well as High-Resolution Transmission Electron Microscopy (HRTEM) imaging, were exploited to understand phase evolution as a function of synthesis time length. Nanoparticles with multiple, well-defined crystalline domains of different crystalline phases were observed, usually surrounded by a thin, amorphous/out-of-axis shell. By increasing the synthesis time length, in addition to the pure α phase, which was rapidly converted into the δ phase at room temperature, a secondary phase, Cs4PbI6, was observed, together with the 715 nm-emitting γ phase

Transient absorption study on Red Vermilion darkening in presence of chlorine ions and after UV exposure

The application of no destructive techniques in the field of Cultural Heritage is becoming fundamental to understanding degradation phenomena. In this study, Transient Absorption (TA) spectroscopy was exploited to explain the process which causes the darkening of Red Vermilion, a famous pigment known also as cinnabar. The optical properties involved in the process are studied in pure HgS and chlorine doped HgS samples, before and after exposure to UV light (365 nm). The study was carried out with particular attention on the ground state bleaching signals, directly connected to the formation of intra-gap trap levels responsible for the pigment degradation. First derivative reflectance spectra reveal the presence of these defectivities, while the analysis of Tauc plots from Kubelka Munk function confirms the reduction of energy band gap due to UV exposure. With the help of Density Functional calculations, we simulated the role of S vacancies in producing a defective alpha-phase, the consequent reduction of the energy band gap and, finally, the progressive phase transformation to the cubic metacinnabar. Transient Absorption turns out to be an important tool of diagnosis about the conservation state of pigments applied in the field of Cultural Heritage

Time through colors: A kinetic model of red vermilion darkening from Raman spectra

Darkening of Red Vermilion (cinnabar) is a well-known phenomenon which needs, at the moment, a full comprehension of its nature. Some paintings reveal a disfiguring process of blackening degradation of Red Vermilion, albeit other relics preserve the original color during the time. The presence of halide elements like Cl− ions, in addition to the light exposure, represents the most alleged cause to explain the darkening phenomenon. However, the real effect of chlorine impurities is still not completely understood. In this study, starting from a multi-technique characterization, we propose a kinetic model of mutual composition of alpha/beta cinnabar derived by the experimental darkening of pure alpha synthetic cinnabar intentionally doped with Cl− ions and treated under prolonged UV light exposure. The model was further applied to ancient samples by analyzing the Raman spectra of antique cinnabar pigments belonging to manuscripts of XIII-XVII centuries

Formation of citrazinic acid ions and their contribution to optical and magnetic features of carbon nanodots: A combined experimental and computational approach

The molecular model is one of the most appealing to explain the peculiar optical properties of Carbon nanodots (CNDs) and was proven to be successful for the bottom up synthesis, where a few molecules were recognized. Among the others, citrazinic acid is relevant for the synthesis of citric acid-based CNDs. Here we report a combined experimental and computational approach to discuss the formation of different protonated and deprotonated species of citrazinic acid and their contribution to vibrational and magnetic spectra. By computing the free energy formation in water solution, we selected the most favoured species and we retrieved their presence in the experimental surface enhanced Raman spectra. As well, the chemical shifts are discussed in terms of tautomers and rotamers of most favoured species. The expected formation of protonated and de-protonated citrazinic acid ions under extreme pH conditions was proven by evaluating specific interactions with H2 SO4 and NaOH molecules. The reported results confirm that the presence of citrazinic acid and its ionic forms should be considered in the interpretation of the spectroscopic features of CNDs

Rapid In Situ Detection of THC and CBD in Cannabis sativa L. by 1064 nm Raman Spectroscopy

The need to find a rapid and worthwhile technique for the in situ detection of the content of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in Cannabis sativa L. is an ever-increasing problem in the forensic field. Among all the techniques for the detection of cannabinoids, Raman spectroscopy can be identified as the most cost-effective, fast, noninvasive, and nondestructive. In this study, 42 different samples were analyzed using Raman spectroscopy with 1064 nm excitation wavelength. The use of an IR wavelength laser showed the possibility to clearly identify THC and CBD in fresh samples, without any further processing, knocking out the contribution of the fluorescence generated by visible and near-IR sources. The results allow assigning all the Raman features in THC- and CBD-rich natural samples. The multivariate analysis underlines the high reproducibility of the spectra and the possibility to distinguish immediately the Raman spectra of the two cannabinoid species. Furthermore, the ratio between the Raman bands at 1295/1440 and 1623/1663 cm-1 is identified as an immediate test parameter to evaluate the THC content in the samples

Corrosive-Abrasive Wear Induced by Soot in Boundary Lubrication Regime

Soot is known to induce high wear in engine components. The mechanism by which soot induces wear is not well understood. Although several mechanisms have been suggested, there is still no consensus. This study aims to investigate the most likely mechanism responsible for soot-induced wear in the boundary lubrication regime. Results from this study have shown that previously suggested mechanisms such as abrasion and additive adsorption do not fully explain the high wear observed when soot is present. Based on the results obtained from tests conducted at varying temperature and soot levels, it has been proven that the corrosive–abrasive mechanism was responsible for high wear that occurred in boundary lubrication conditions

Chinese Influence in Central Eastern Europe during the global economic crisis

The access of many former members of the Warsaw Pact into the European Union represents the top of the “westernization” process begun during 1990s. The access into the EU represented also a big flood of funds to Central-Eastern Europe (CEE), but the new members haven’t always been able to make a correct use of the European grants. During the last years the economic crisis heavily affected Central European Countries. Only Poland seems to resist the crisis’ hits. Considering the current difficulties of the European Union and its main members, CEE countries started to look to East, especially to the second economy of the world and potentially the first in a perspective of few years to come: China. Chinese funds and investments are interpreted as a possible way out from the economic difficulties. On the Asian side, Chinese enterprises are more and more interested to invest their money and resources in Central East European countries because they can represent the starting point to enter into EU market bypassing the strict European anti-dumping set of rules

Summer 1953, Bucharest: The Third World Youth Congress and The Fourth World Youth Festival. The Italian Concerns

On summer 1953, Bucharest hosted the Third World Youth Congress and the Fourth World Youth Festival. The World Youth Congress and the World Youth Festival were periodically settled up by the World Federation of Democratic Youth, an international organization close to the Soviet Union. These periodic events got thousands and thousands of young peopl e together from around the world. Most of participants were communists, but the Festival in particular attracted youth with different political ide as. Obviously, during these occasions, communist authorities tried to spread their p ropaganda, creating great concern among Western countries and especiall y Italy. Because its timing, the events held in Bucharest on summer 1953 became a major issue among Western diplomacie

Seen from abroad: Sino-Romanian relations from 1949 to 1989 in the Italian press

This work on Sino#12;Romanian relations from 1949 to 1989 seen by Italian press born as spin#12;off of my Ph. D. research about the evolution of lies between Romania and East Asian countries. First aim of this art icle is to understand if Italian press was aware of the ties between B ucharest and Beijing and how much strict were that ties. Actually, Italian press monitored the evolution of Sino#12;Romanian relations mainly on the circumstances of State visits accomplished by the leaders of the two countries. Example s of these State visits are that of Chinese Prime Minister Zhou Enlai in Buchare st on June 1966 and that accomplished by Nicolae Ceauşescu in China on Ju ne 1971. Articles written by Italian journalists are based on news from Romanian and Chinese newspapers, on news from international press agencies and on official statements and communiqués. We can find also some report and a nalysis, signed by special correspondents as Massimo Conti and Sergio Mugnai. For this work, I’ve utilized the following newspapers: #1; Corriere della Sera , the main newspaper of Italy. #1; La Stampa , printed in Turin, owned by Agnelli’s industrial family. #1; L’Unità , mouthpiece of the Italian Communist Party. #1; La Repubblica , newspaper founded on 1976. #1; Avanti! , mouthpiece of the Italian Socialist Part