Application of benchtop total-reflection X-ray fluorescence spectrometry and chemometrics in classification of origin and type of Croatian wines

The contents of selected metals (K, Ca, Fe, Cu, Zn, Mn, Sr, Rb, Ba, Pb, Ni, Cr and V) in 70 wine samples from Continental and Adriatic part of Croatia and different types of wine (red and white) were determined by TXRF. The aim of this study was to compare the elemental composition of wines from two different regions and to determine the discriminant ability of each variable and to indicate which variables discriminate between the four categories considered. Principal component analysis and cluster analysis showed that K, Mn, Ba and Ni can be considered as the most important characteristics to distinguish between Continental red and white wines, Rb, Ni and Ba for Continental red and Adriatic red wines while Sr is the only metal that completely distinguishes the samples of each category. Finally, linear discriminant analysis showed good recognition (100%) and prediction abilities (96.43%) using these selected elements

High Pressure phase transitions in BaWO4

Using in-situ angle dispersive x-ray diffraction, we have shown that barium tungstate, which exists in scheelite phase at ambient conditions, transforms to a new phase about seven giga pascal. Analysis of our data based on Le bail refinement suggests that this phase could be fergusonite and not mercuric molybdate type, which was proposed earlier from the Raman investigations. Beyond fourteen giga pascal this compound undergoes another phase transformation to a significantly disordered structure. Both the phase transitions are found to be reversible.Comment: 14 pages with 4 figures and 1 tabl

Thermodynamics of mechanical transduction of surface confined receptor/ligand reactions

Chemomechanics of surface stress is discussed in terms of interfacial thermodynamics. In the first section the paper shows how to quantitatively describe the chemical equilibrium of a receptor/ligand binding reaction confined at a solid-liquid interface and how the overall work of the reaction splits into chemical and surface work, that appears as a surface pressure. In the second section this thermodynamic model is applied to describe the experimental results of microcantilever bending induced by DNA hybridization occurring onto one of its face

Elemental analysis of teas, herbs and their infusions by means of total reflection X-ray fluorescence

This work shows that total reflection X-ray fluorescence (TXRF) is a suitable tool for multi-elemental analysis of teas, herbs and their infusion. A low power benchtop TXRF spectrometer was used. Safety of infusion consumption was evaluated. Many commercially available teas,herbs and roots samples were analyzed. Total concentrations of thirteen elements K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Ba and Pb as well as their extraction efficiencies into infusion were determined. The content of Pb is highlighted in all teas and herbs, in the concentration range between 0.5 and 4.8 mg/g, but only in infusions of herbs. Chemometry was applied for classification purposes. Elemental daily intakes with respect to infusion drinking was calculated and compared with dietary reference intake values. Results show that TXRF is a fast and simple technique for safety check of tea and herb infusions on a routine basis

Erbium incorporation in LiNbO3 crystals obtained by ion-exchange process

Erbium local doping of LiNbO3 single crystal by the ion-exchange has been performed. The role of the process parameters such as exchange time and temperature, crystal cut direction, composition and heating rate of the Er ions liquid source has been investigated by means of secondary ion mass spectrometry, X-ray diffraction and micro-lumi- nescence techniques. A theoretical model has been presented for describing the ion-exchange process and has been successfully applied to fit the experimental data. We have demonstrated that the method is suitable for Er-doping of LiNbO3 crystals, with the possibility of tailoring the optical performances of the material through the preparation parameters

Study of sea water influence on chemical and physical degradation of Roman Glass

From ancient times to today glasses, generally based on siliceous oxides cooled to a hard condition to avoid crystallization, have been extensively used, for their chemical-physical durability. Indeed, glass is one of the materials most frequently discovered during archaeological excavations. The degradation induces the loss of brightness and transparency, and the formation of pits, crystals and patinas. Sometimes peeling layers may appear, too. All these phenomena alter irreversibly the aesthetic appearance of the glassworks. The research in this field, initially focused on the knowledge of history, composition and technology of the manufacture of works of art is trying now to rationalize the problems connected with degradation processes through, both, very sensitive characterization techniques and model experiments simulating degradation phenomena. In this work we deepen the analyses of glass degradation regarding samples coming from the Roman ship Iulia Felix found on the seabed of Grado lagoon (Italy) and dated to the II century A.D. Their surfaces have been investigated through XPS (X-Ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectrometry) to understand water effects on glass degradation and interesting considerations on the mobility of the present ionic species are proposed. We also report the results of micro-XRF and synchrotron-XRD analyses that will allow us to single out the various crystallization species present resulting from the degradation phenomena of these glasses