A new approach to the authentication of goldwork

The study of goldwork encompasses several large fields of investigations. Scientific analyses can respond to questions concerning production techniques, provenance and preservation. However, what about authentication? This type of works of art generally has very high prices, leading to an increase in the number of forgeries. Today, fakes can imitate artworks produced by most civilisations and with different origins. Moreover, most of the objects we analyse cannot be submitted to destructive sampling. That is the reason why we employ external-beam PIXE for the analysis of such objects, a method able to offer reliable and non-intrusive scientific investigations. Our methodology consists of two steps, which, in their combination, provide information about the chronological compatibility of the objects with their presumed period. First, an optical and electronic microscope investigation allows us to identify tool marks, weathering features, to reveal traditional or fraudulent surface treatments, and to characterise superficial deposits. This first approach is able to identify bad quality fakes. However, these analyses are generally insufficient to establish the authentication of the objects. That is why we also perform external-beam PIXE analyses on goldwork. Thus, the qualitative and quantitative studies of trace elements are able to provide insights into metallurgical methods and the fineness of alloys. This paper describes our methodology and presents different examples of its application, including the discussion of specific problems encountered in the analysis of this type of objects.Les objets en or sont étudiés par des approches très diverses, et parmi celles-ci les analyses scientifiques répondent généralement à des problématiques concernant la recherche des techniques de fabrication ou l’étude de provenance et de conservation. Mais, qu’en est-il de l’authentification ? Ce type d’objets d’art étant en effet d’une valeur marchande élevée, ils sont de plus en plus souvent sujets à des contrefaçons, qui imitent aujourd’hui la plupart des styles et des civilisations. Les investigations scientifiques doivent être absolument non destructive et la technique PIXE en faisceau extrait est alors idéale pour ce type d’expertise. Nous avons ainsi développé une méthodologie qui nous fournira un faisceau d’indices qui sera compatible ou pas avec l’ancienneté présumée de l’objet. En premier lieu, l’examen par microscopie optique et électronique permet d’identifier les traces d’outils, les figures de corrosion, de révéler si l’objet a subi des traitements de surface anciens ou modernes et de caractériser la nature des dépôts superficiels. Ce premier niveau d’investigation permet d’écarter les faux flagrants ou de mauvaise qualité. Toutefois, cette étude est généralement insuffisante pour établir l’ancienneté d’un objet en or. C’est pourquoi, nous réalisons en complément une étude par PIXE en faisceau extrait qui détermine la composition en éléments traces, eux-mêmes révélateurs des méthodes métallurgiques et de la pureté des alliages. Ce texte décrit cette méthodologie et présente différents exemples d’application en précisant les problèmes auxquels nous avons été confrontés sur les différents types d’objets rencontrés

Neutrino, wine and fraudulent business practices

The search for the neutrino and its properties, to find if it is a Dirac or Majorana particle, has kept physicists and engineers busy for a long time. The Neutrino Ettore Majorana Observatory (NEMO) experiment and its latest demonstrator, SuperNEMO, demanded the development of high-purity low-background $\gamma$-ray detectors to select radioactive-free components for the demonstrator. A spin-off of these detectors is inter-disciplinary measurements, and it led to the establishment of a reference curve to date wines. In turn, this proved to be an effective method to fight against wine counterfeiters

Neutrino, wine and fraudulent business practices

The search for the neutrino and its properties, to find if it is a Dirac or Majorana particle, has kept physicists and engineers busy for a long time. The Neutrino Ettore Majorana Observatory (NEMO) experiment and its latest demonstrator, SuperNEMO, demanded the development of high-purity low-background γ-ray detectors to select radioactive-free components for the demonstrator. A spin-off of these detectors is inter-disciplinary measurements, and it led to the establishment of a reference curve to date wines. In turn, this proved to be an effective method to fight against wine counterfeiters

PCA and PMF based methodology for air pollution sources identification and apportionment

Air pollution is a wide concern for human health and requires the development of air quality control strategies. In order to achieve this goal pollution sources have to be accurately identified and quantified. The case study presented in this paper is part of a scientific project initiated by the French Ministry of Ecology and Sustainable Development. For the following study measurements of chemical composition data for particles have been conducted on a french urban site. The first step of the study consists in the identification of the sources profiles which is achieved through Principal Component Analysis completed by a rotation technique. Then the apportionment of the sources is evaluated with a receptor modeling using Positive Matrix Factorization as estimation method. Finally the joint use of these two statistical methods enables to characterize and apportion five different sources of fine particulate emission

Pollution sources detection via principal component analysis and rotation

Air pollution is a widely preoccupation which needs the development of control strategies. To reach this goal, pollution sources have to be precisely identified. Principal component analysis is a possible response to this problem. Indeed this factorial method enables to detect sources, that is to have a qualitative description of them. In this work, techniques of rotation are a useful help for the association of variables with factors. We highlight the fact that the rotation must be applied to the standardized principal components, so as to keep good interpretation properties. This methodology has then been applied to a problem of air pollution on a french site

Pollution sources detection via principal component analysis and rotation

Air pollution is a widely preoccupation which needs the development of control strategies. To reach this goal, pollution sources have to be precisely identified. Principal component analysis is a possible response to this problem. Indeed this factorial method enables to detect sources, that is to have a qualitative description of them. In this work, techniques of rotation are a useful help for the association of variables with factors. We highlight the fact that the rotation must be applied to the standardized principal components, so as to keep good interpretation properties. This methodology has then been applied to a problem of air pollution on a french site

World forests, global change, and emerging pests and pathogens

International audienceGlobal changes play today an important role in altering patterns of human, animal, and plant host–pathogen interactions and invasive pest species. With rapid development in sequencing technology, there is also an increase in pathogen and pest studies adopting a macroscale, biogeographical perspective, and we present the most recent elements on existing ecological and biogeographical trends. We also compare the results on the one hand on emerging infectious diseases of animals and humans, and on the other hand on plant pathogens and pests. International exchanges of people, animals, and plant products currently contribute to their geographical extension but with notable differences across disease and pest systems, and regions. This review highlights that the subject of pathogens and plant pests, traditionally rooted in agronomic approaches, lacks work on macroecology and biogeography. We discuss the research orientations to better anticipate their ecological and economic impacts in order to better achieve environmental sustainability

Kerosene space heaters: a major source of ultrafine particles indoors

Kerosene heaters are known to emit pollutants in the indoor environment but ultrafine particle emission was never reported. A kerosene heater was characterized in an experimental chamber using four different instruments to monitor particle number concentration and size distribution down to 5 nm. Another experiment was realized to collect particles and determine their composition in elements, ions, organic/elemental carbon and polycyclic aromatic hydrocarbons. The kerosene heater produced ultrafine particles in the range 5 to 40 nm with a count median diameter of 9.5 nm. The emission rate was (1.8±0.3)×1011 particle*s-1. Chromium and manganese (4 and 0.05 ng*g-1 of burned fuel) were specifically associated with kerosene combustion. Trace levels of sulfates, nitrates, phenanthrene and fluoranthene were also detected. Scanning electron microscopy showed submicronic aggregates mostly composed of carbon and traces of silicon. Our findings showed that kerosene heaters represent a major indoor source of ultrafine particles

Kerosene space heaters: a major source of ultrafine particles indoors

Kerosene heaters are known to emit pollutants in the indoor environment but ultrafine particle emission was never reported. A kerosene heater was characterized in an experimental chamber using four different instruments to monitor particle number concentration and size distribution down to 5 nm. Another experiment was realized to collect particles and determine their composition in elements, ions, organic/elemental carbon and polycyclic aromatic hydrocarbons. The kerosene heater produced ultrafine particles in the range 5 to 40 nm with a count median diameter of 9.5 nm. The emission rate was (1.8±0.3)×1011 particle*s-1. Chromium and manganese (4 and 0.05 ng*g-1 of burned fuel) were specifically associated with kerosene combustion. Trace levels of sulfates, nitrates, phenanthrene and fluoranthene were also detected. Scanning electron microscopy showed submicronic aggregates mostly composed of carbon and traces of silicon. Our findings showed that kerosene heaters represent a major indoor source of ultrafine particles