In 2008 the rostrum from an ancient warship was recovered from the Mediterranean near Acqualadrone, Sicily. To establish its provenance and condition, samples of black and brown rostrum wood were ...examined using sulfur K-edge x-ray absorption spectroscopy (XAS) and GC-MS. GC-MS of pyrolytic volatiles yielded only guaiacyl derivatives, indicating construction from pinewood. A derivatized extract of black wood yielded forms of abietic acid and sandaracopimaric acid consistent with pine pitch waterproofing. Numerical fits to the sulfur K-edge XAS spectra showed that about 65% of the endogenous sulfur consisted of thiols and disulfides. Elemental sulfur was about 2% and 7% in black and brown wood, respectively, while pyritic sulfur was about 12% and 6%. About 2% of the sulfur in both wood types was modeled as trimethylsulfonium, possibly reflecting biogenic dimethylsulfonio-propionate. High valent sulfur was exclusively represented by sulfate esters, consistent with bacterial sulfotransferase activity. Traces of chloride were detected, but no free sulfate ion. In summary, the rostrum was manufactured of pine wood and subsequently waterproofed with pine pitch. The subsequent 2300 years included battle, foundering, and marine burial followed by anoxia, bacterial colonization, sulfate reduction, and mobilization of transition metals, which produced pyrite and copious appended sulfur functionality.
A Ce:YAG-poly(methyl methacrylate) (PMMA) composite was prepared by using the melt compounding method. The structure and morphology were investigated by X-ray diffractometry, transmission electron ...microscopy, and small-angle X-ray scattering. The optical properties (emission, excitation, and fluorescence decay rate) of the composite were studied by using photoluminescence spectroscopy. The polymer–filler interactions were studied using 13C cross-polarization magic-angle spinning NMR spectroscopy (13C{1H} CP-MAS NMR). The results indicated that Ce:YAG particles are well-dispersed in the PMMA matrix without loss of their luminescence properties or significant spectral shift, thus suggesting that this composite can be valuable for advanced applications in white LED manufacture. A demonstration of its efficiency in white LED devices is also reported.
Nanodispersions of pristine single‐wall carbon nanohorns (i.e., p‐SWCNHs) and oxidized‐SWCNHs (i.e.; o‐SWCNHs) were used to modify screen printed electrode (SPE). p‐SWCNHs and o‐SWCNHs were fully ...characterized by using several analytical techniques, as: HR‐TEM (High Resolution‐Transmission Electron Microscopy), FE‐SEM/EDX (Field Emission‐Scanning Electron Microscopy/Energy Dispersive X‐ray Analysis), Raman spectroscopy, thermogravimetric analysis, differential thermal analysis (DTA), and the Brunauer‐Emmett‐Teller (BET) method. The chemically modified SPEs were also characterized with Cyclic Voltammetry (CV), using several different electro‐active targets. In all cases, p‐SWCNHs showed better performances than those obtained for o‐SWCNHs as well as with respect to conventional Glassy Carbon (GC) electrodes, in terms of peak currents, significant shift at lower redox‐potential ranges and enhanced heterogeneous apparent kinetic constants.
Nd:YAG nanopowders were prepared using the
Pechini process with microwave irradiation (
MWs). A
reference sample was also prepared using conventional heating.
XRD pattern analysis showed that ...nanopowder obtained by means of conventional heating and calcination for 1
h at 900
°C has a structure made up of the garnet phase together with the hexagonal phase that disappeared after two additional hours of thermal treatment. The
MWs powder calcined for 1
h consists of the single garnet phase. SAXS data analysis indicated that nanoparticles are characterized by a sharp interface. TEM investigation showed crystalline particles with remarkable agglomeration in both samples, although a more homogeneous size of particles was evident in the
MWs sample as compared to the
reference sample.
The rate, the calcination time and the quality of the powder obtained make the
Pechini process with microwave irradiation an attractive alternative procedure to conventional YAG preparation methods.
Nanolime dispersed in 2-propanol was extensively used for the consolidation of wall paintings. The knowledge of the advances of this methodology dealing with all the possible effects associated with ...the nanolime new material in conservation is fundamental to assess and improve the technique. In this paper, four different dispersions of Ca(OH)2 nanoparticles were characterised by Small Angle X-rays Scattering technique (SAXS) and Transmission Electron Microscopy (TEM) in order to achieve information on size, shape, polydispersity, agglomeration, and crystal structure (by SAED patterns) of the particles. Once characterised, the dispersions were tested in two different case studies, the Carceri dello Steri in Palermo with their graffiti and the 18th century lunettes at the SS. Giuda e Simone Cloister, Corniola (Empoli) with their lime-based mural paintings. The treated samples were characterised in relationship to either their morphology and surface chemical composition by Scanning Electron Microscopy coupled with Energy Dispersive X-rays spectroscopy (SEM-EDX), or their water absorption and mechanical properties (resistance to material abrasion). The results obtained showed that all the dispersions were nanometrically structured and their application succeeded in recovering the mechanical properties of the painting or graffito layers, not altering their permeability to water and keeping perfectly the wall transpiration. However, the dispersions constituted of the nanoparticles obtained via a synthesis able to control size and shape of the Ca(OH)2 particles resulted in a better performance in situ, even if the differences found by SAXS and TEM were slight.
In this work a careful ICP-OES and ICP-MS investigation of 38 ancient ingots has been performed to determine both major components and trace elements content to find a correlation between the ...observed different features and the composition.
The ingots, recovered in an underwater archaeological site of various finds near Gela (CL, Italy), were previously investigated by X-Ray Fluorescence (XRF) spectroscopy to know the composition of the alloy and it was found that the major elements were copper and zinc, in a ratio compatible with the famous orichalcum similar to the contemporary brass that was considered a precious metal in ancient times. The discovery of huge amount this alloy is extraordinary.
Following a chemometric approach at first, the use of Principal Component Analysis (PCA) and Cluster Analysis (CA) allowed us to highlight three well-defined groups of ingots and to point out three ingots that appeared outlier with respect to the whole sample set. Linear Discriminant Analysis (LDA) and Soft Independent Modeling of Class Analogy (SIMCA) enabled us to confirm the difference between the hypothesized groups. The prediction power of the variables computed by SIMCA allowed us pointing out some elements able to differentiate each group.
The three well-defined groups of ingots resulting from the chemometric analysis were in agreement with the observations of some morphological parameters such as ingot shape, width, and length and weight and by the presence of different kind of patina.
The appearance of three distinctive families of ingots can indicate different geographical location of the furnace, different technology stages and/or different raw material used in melting process and the morphology is indicative of cast diverse technologies. These findings can signify the starting point for giving important insights in the archaeometric study of the orichalcum ingots regarding the provenience and the manufacture technologies.
•Orichalcum ingots analysis of main and trace elements.•Main and trace elements of the orichalcum ingots were obtained by using ICP-OES and ICP-MS techniques.•Clustering and principal component analyses were used to infer the presence of three well defined groups.•The studies including the visual examination gave information on the different manufactures in the production methods of the ingots.
Ce:YAG-polycarbonate composites were prepared with several amounts of Ce:YAG in the range 0.1–5 wt.% by using melt compounding. The structure and morphology of the composites were investigated by ...means of X-ray diffractometry and transmission electron microscopy. The optical properties of the composites were studied by using photoluminescence spectroscopy. The intermolecular interaction between the polymer and the filler surface was investigated using 13C cross-polarization magic-angle spinning NMR spectroscopy (13C {1H} CP-MAS NMR). The results showed that the dispersion of the particles in the polymer, and the optical properties, depend on the Ce:YAG amount. The composites were combined with a blue LED in order to test their performance in a white LED device. Results indicate that more suitable light is obtained using the Ce:YAG-PC composite loaded at 2 wt.%.
Display omitted
•Preparation of new Ce:YAG/polycarbonate composite.•Influence of concentration on the optical properties of the composite.•Use of composite in the develop of a white led.
PDF
