Imaging heritage and other metal surfaces with X-ray excited optical microscopy

Heritage tourism represents a significant source of income for the European Union. Metals are vital to this, but corrode and degrade over time unless curative actions are taken. Conservators require non-destructive analysis techniques and specific instrumentations for the study and analysis of ancient objects that comprise our tangible cultural heritage. XEOM 1, a novel X-ray-excited optical microscopy system, is presented as a new addition to the conservator’s toolbox. XEOM 1 allows non-destructive chemical imaging of heritage metal surfaces (approximately top 200 nm) in air and controlled atmosphere. XEOM exploits the effect in which X-ray absorption results in the emission of electromagnetic radiation in the visible and near-visible bands, a phenomenon known as X-ray-excited optical luminescence (XEOL). The work presented in the thesis comprises ground work for imaging of copper and copper corrosion products on assessment samples of varying patination; a multimethod analysis of heritage artefacts retrieved from King Henry VIII's flagship: the 'Mary Rose' and the study for an alternative excitation source for use of XEOM 1 outside the synchrotron. The research and development of X-ray-excited optical microscopy was supplemented with the research regarding the copper corrosion of frameless coppr and copper- gold intrauterine devices (IUDs)

XEOM 1 : a novel microscopy system for the chemical imaging of heritage metal surfaces

Background: We describe a novel microscopy system which can obtain chemical maps from the surfaces of heritage metals in air or a controlled environment. The microscope, x-ray excited optical microscope Mk 1 (XEOM 1), forms images from x-ray excited optical luminescence (XEOL) induced by illuminating a few square millimetres of the sample with monochromated x-rays (broad beam or macroprobe illumination). XEOL is a spectroscopy tool in its own right and can, under the right circumstances, also be a vehicle for x-ray absorption spectroscopy. This (usually) synchrotron based technique provides information on the chemical state and short-range atomic order of the top few microns of a surface. It is thus well suited to heritage metal corrosion studies and is complementary to synchrotron x-ray diffraction. Results: Imaging can be performed by scanning the sample under an x-ray microprobe. We show elsewhere that the power density needed for image acquisition on a reasonable time-scale is high enough to damage a patina and modify its chemistry. Although the damaged region may be invisible to the human eye, the data are characteristic of the damage and not the native chemistry of the surface. A macrobeam power density can be 4 orders of magnitude smaller than that for a microbeam and no surface modification was observed on test samples. Features of the instrument are demonstrated using copper test surfaces with a spatially varying patination to establish the ground work for the imaging of copper, cuprite, nantokite and atacamite/paratacamite and a first application from a bronze chain mail link. In parallel we have developed a suite of imaging software which can process XEOM image stacks to produce reduced data sets characteristic of various aspects of the surface chemical map. These include edge-shift (oxidation state) images and edge height (high contrast) images and spectra from user defined regions of interest. Conclusions: The technique can map the oxidation state of a surface from shifts in the absorption edge energy across columns of pixels in an image set, and map particular compounds from their characteristic XANES spectra. Optically filtered images give improved chemical selectivity and the data sets contain as yet untapped information sources

Вимоги до матеріалів, що приймаються до друку в збірнику наукових праць "Cучасна українська політика. Політики і політологи про неї"

We investigated the temporal variation of pelagic and benthic food sources in the diet of benthic taxa at a depositional site in the Southern Bight of the North Sea by means of fatty acid (FA) biomarkers and compound-specific stable isotope analysis (CSIA). The taxa were the non-selective deposit feeding nematodes (<em>Sabatieria</em> spp. and ‘other nematodes’), and three dominant macrobenthic species: two true suspension-deposit feeders (the bivalve <em>Abra alba</em> and the tube dwelling polychaete <em>Owenia fusiformis</em>) and the suspected predatory mud-dwelling anemone <em>Sagartia</em> sp. These species make up on average 16% (<em>Abra alba</em>), 17% (<em>Sagartia</em> sp.) and 20% (<em>Owenia fusiformis</em>) of the biomass in the <em>Abra alba–Kurtiella bidentata</em> community in this area. Phytoplankton dynamics in the suspended particulate matter of the water column as inferred from cell counts, chlorophyll-<em>a</em> and organic carbon content were clearly visible in sediment and animal FA abundance as well, whereas phytodetritus dynamics in the sediment FA composition were less clear, probably due to patchy distribution or stripping of FA by macrofauna. Nematodes appeared to assimilate mainly Polyunsaturated Fatty Acids (PUFAs) from their sedimentary environment and were further non-selectively accumulating more (<em>Sabatieria</em> spp.) or less (‘other nematodes’) FA from the deposited phytodetritus. In contrast, <em>Abra alba</em> FA composition was consistent with a diatom-dominated diet and consumption of <em>Phaeocystis</em> was observed in <em>Owenia fusiformis,</em> whereas <em>Sagartia</em> sp. showed evidence of a predatory behaviour. While the total FA content in <em>Owenia fusiformis</em> remained constant throughout the year, <em>Sagartia</em> sp. doubled and <em>Abra alba</em> increased its FA level more than 10-fold in response to the organic matter deposition from the phytoplankton bloom. This leads to the conclusion that there is no resource partitioning between non-selective deposit feeding nematodes and the suspension-deposit feeding macrobenthic organisms, suggesting they belong to separate parts of the benthic food web

Synchrotron X-ray diffraction investigation of the surface condition of artefacts from King Henry VIII's warship the Mary Rose

Synchrotron X-ray diffraction (XRD) measured on the XMaS beamline at the ESRF was used to characterize the alloy composition and crystalline surface corrosion of three copper alloy Tudor artefacts recovered from the undersea wreck of King Henry VIII's warship the Mary Rose. The XRD method adopted has a dynamic range ∼1:105 and allows reflections <0.002% of the height of major reflections in the pattern to be discerned above the background without smoothing. Laboratory XRD, scanning electron microscopy–energy dispersive spectroscopy, synchrotron X-ray fluorescence and X-ray excited optical luminescence–X-ray near-edge absorption structure were used as supporting techniques, and the combination revealed structural and compositional features of importance to both archaeology and conservation. The artefacts were brass links believed to be fragments of chainmail and were excavated from the seabed during 1981 and 1982. Their condition reflects very different treatment just after recovery, viz. complete cleaning and conservation, chemical corrosion inhibition and chloride removal only, and distilled water soaking only (to remove the chlorides). The brass composition has been determined for all three at least in the top 7 µm or so as Cu(73%)Zn(27%) from the lattice constant. Measurement of the peak widths showed significant differences in the crystallite size and microstrain between the three samples. All of the links are found to be almost chloride-free with the main corrosion products being spertiniite, sphalerite, zincite, covellite and chalcocite. The balance of corrosion products between the links reflects the conservation treatment applied to one and points to different corrosion environments for the other two

How do patients with chest pain access Emergency Department care?

BACKGROUND: It is important that patients with symptoms of acute coronary syndrome receive appropriate medical care as soon as possible. Little is known about the preadmission actions that patients with chest pain take before arrival at the Emergency Department (ED). OBJECTIVE: This study aimed to describe the actions of patients with chest pain or pressure after onset of symptoms. What is the first action following onset of symptoms? Who is the first lay or professional person to be contacted? Which steps are taken first? How is the patient transported to the hospital? METHODS: Consecutive patients, arriving at the ED of two large hospitals in Belgium, were asked additional questions during the initial assessment. RESULTS: Overall, 35% of 412 consecutive patients with chest pain admitted to the ED were diagnosed with acute coronary syndrome. A total of 57% contacted a GP between symptom onset and arrival at the ED. Only 32% of the patients were transported to the ED by ambulance, 16% drove themselves and 52% arrived by other means of transport (by family, neighbour, GP, public transport). CONCLUSION: In Belgium, the GP is still the first professional to be contacted for most patients. Other patients initially rely on their partner, family or friends when symptoms emerge. Too often, patients with chest pain rely on other transport to get to the ED instead of calling the Emergency Medical Services. This study included only patients who ultimately attended the ED.status: publishe

In situ time-lapse synchrotron radiation X-ray diffraction of silver corrosion

Several heritage systems have been studied using state-of-the-art synchrotron techniques. The cultural heritage value of silver is documented in museum collections across the globe. However, the silver surface is not as chemically stable as that of other precious metals, and is susceptible to corrosion by atmospheric gases. It is therefore of special interest to clarify these surface reactions by using in situ, time-lapse chemical and structural analysis in controlled ambients in order to develop strategies to reduce or even prevent the atmospheric attacks. In order to study the initial corrosion processes of silver in the presence of corrosive gases in situ time-lapse X-ray diffraction experiments were performed on the XMaS beamline at the European Synchrotron Radiation Facility, Grenoble. Highly pure silver samples were weathered with synthetic air containing 500 ppb of both H2S and ozone, at relative humidity (RH) levels, and XRD patterns were tracked every 10 min over a total weathering time of 24 h. The time-lapse Synchrotron Radiation (SR)-XRD data show that pure silver exposed to those atmospheres starts to form crystalline corrosion products after only 10 minutes. Silver sulfates, silver oxides, intermediates and mixed species are formed on the sample surface over the duration of the experiment. The data collected using a newly combined environmental cell/gas flow set up introduces a set of highly useful tools for scientists who wish to study time-lapse gaseous corrosion at ambient temperature and pressure