Materials and technological aspects of gilded buckles from a North Eastern Medieval Italian context

This study concerns the archaeometric characterization of two artefacts from the medieval site of San Rocco (Castelfranco Veneto, Italy). Both of them belong to a larger set of metallic objects, some being part of tomb ornaments belonging to two very well distinct periods of frequentation of the site. Both items are buckles and they have been selected as representative of two very well-known and established typologies. The older one, at the end of the sixth—beginning of the seventh century AD, is made of silver, although relicts of gold have been found. A number of relevant counterparts of this item have been found in different sites of the Longobard Italy. The main body of the second artefact (second half of the fourteenth century AD) consists of a bent strip of a copper rich alloy, coated on one side with a nearly continuous, decorated, gold layer. This is a so-called lyre-buckle, with a widespread diffusion not only in Italian, but also North European contexts. From the results of the analyses carried out using low-vacuum scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry, information on manufacturing, gilding technology and materials have been obtained that will be an useful benchmark for the archaeometric characterization of similar items from selected collections. In this way, the already established typological affinity of these two classes of items will be extended to technological and materials aspects, also.     

Natural Abundance 15N and 13C Solid‐State NMR Chemical Shifts: High Sensitivity Probes of the Halogen Bond Geometry

Solid‐state nuclear magnetic resonance (SSNMR) spectroscopy is a versatile characterization technique that can provide a plethora of information complementary to single crystal X‐ray diffraction (SCXRD) analysis. Herein, we present an experimental and computational investigation of the relationship between the geometry of a halogen bond (XB) and the SSNMR chemical shifts of the non‐quadrupolar nuclei either directly involved in the interaction (¹⁵N) or covalently bonded to the halogen atom (¹³C). We have prepared two series of X‐bonded co‐crystals based upon two different dipyridyl modules, and several halobenzenes and diiodoalkanes, as XB‐donors. SCXRD structures of three novel co‐crystals between 1,2‐bis(4‐pyridyl)ethane, and 1,4‐diiodobenzene, 1,6‐diiodododecafluorohexane, and 1,8‐diiodohexadecafluorooctane were obtained. For the first time, the change in the ¹⁵N SSNMR chemical shifts upon XB formation is shown to experimentally correlate with the normalized distance parameter of the XB. The same overall trend is confirmed by density functional theory (DFT) calculations of the chemical shifts. ¹³C NQS experiments show a positive, linear correlation between the chemical shifts and the C?I elongation, which is an indirect probe of the strength of the XB. These correlations can be of general utility to estimate the strength of the XB occurring in diverse adducts by using affordable SSNMR analysis.     

Extreme‐ultraviolet compact spectrometer for the characterization of the harmonics content in the free‐electron‐laser radiation at FLASH

The design and the commissioning results of a portable and compact spectrometer for the high harmonics content characterization of the extreme‐ultraviolet radiation of FLASH (free‐electron laser in DESY, Hamburg, Germany) are presented. The instrument is a grazing‐incidence flat‐field spectrometer equipped with two variable‐line‐spaced gratings; it covers the 2–40 nm wavelength region with a spectral resolution in the 0.1–0.2% range. Both spectral and intensity fluctuations of the fundamental emission and the harmonics are monitored.     

Dynamics of spiral waves in a cardiac electromechanical model with a local electrical inhomogeneity

Joint effect of electrical heterogeneity (e.g. induced by ischemia) and mechanical deformation is investigated for an anisotropic, quasi–incompressible model of cardiac electromechanical coupling (EMC) using the active strain approach and periodic boundary conditions. Three local inhomogeneities with different geometry are simulated. Under a specific stimulation protocol, the heterogeneities are able to induce spirals. The interplay between the dimension of the electrical inhomogeneity, the EMC and the mechano-electrical feedback provided by the stretch activated current (SAC) determines the dynamics of the spiral waves of excitation, which could extinguish (in the case of low SAC), or be stable (with the tip rotating inside the inhomogeneity), or drift and be annihilated (in the case of high SAC).     

Static and dynamic headspace analysis of instant coffee blends by proton‐transfer‐reaction mass spectrometry

Instant coffee is a widespread product, generally related to a high consumer acceptability, also because of its ease of preparation. The present work addresses the characterization of the headspace of freshly brewed instant coffees resulting from different blends, during and immediately after preparation. The sample set consisted of 10 coffees, obtained by mixing three different blends in different proportions. The employment of Proton Transfer Reaction‐Mass Spectrometry (PTR‐MS) allowed for direct and real‐time sampling from the headspace, under conditions that mimic those that are encountered above the cup during and right after brewing. Different coffee brews were separated on the basis of the respective volatile profiles, and data showed good consistency with the respective blend compositions. When the headspace evolution was monitored during preparation, similar results were obtained in terms of blend separation; moreover, different blends displayed different and reproducible ‘signatures’ in terms of time evolution. A straightforward method for the prediction of headspace composition is proposed, allowing to predict the volatile profiles of two‐component and three‐component blends on the basis of the respective parent components. Overall, the results constitute a successful example of the applicability of PTR‐MS as a tool for product development in food science. Copyright © 2015 John Wiley & Sons, Ltd.