Micro-SORS, diffusion processes and heritage science: a non-destructive and systematic investigation

2021 ◽  
Vol 136 (8) ◽  
Author(s):  
A. Botteon ◽  
M. Realini ◽  
C. Colombo ◽  
C. Conti ◽  
P. Matousek ◽  
...  
2014 ◽  
Vol 1 ◽  
pp. 155-172 ◽  
Author(s):  
Ivan Procházka ◽  
Jakub Čížek ◽  
Oksana Melikhova ◽  
Wolfgang Anwand ◽  
Tetyana E. Konstantinova ◽  
...  

In the present work, zirconia (ZrO2) nanopowders doped with yttria (Y2O3) and chromia (Cr2O3) were prepared by a co-precipitation technique. The nanopowders were then subjected to a calcination and a successive sintering at elevated temperatures up to 1500 °C. The nanostructures in these nanomaterials were characterized by positron annihilation spectroscopy (positron lifetimes and Doppler broadening measurements) which is a non-destructive technique with a high sensitivity to atomic-scale open-volume defects. It was found that the zirconia-based nanomaterials studied contain vacancy-like defects and nanoscale pores. Diffusion processes induced in these nanomaterials by sintering were investigated also by depth sensitive positron annihilation studies using a variable energy slow positron beam. Sintering was found to cause intensive grain growth and a removal of porosity by a migration of pores from the sample interior toward its surface.


2013 ◽  
Vol 26 ◽  
pp. 25-31
Author(s):  
Oksana Melikhova ◽  
Jakub Čížek ◽  
Ivan Procházka ◽  
Wolfgang Anwand ◽  
Tetyana E. Konstantinova ◽  
...  

In the present work, zirconia-based nanomaterials with various stabilizers were prepared by a co-precipitation technique. Defects in these nanomaterials were characterized by positron annihilation spectroscopy which is a non-destructive technique with a high sensitivity to open volume defects and atomic scale resolution. It was found that zirconia-based nanomaterials contain vacancies and also nanoscale and meso-scale pores. Diffusion processes which occur in the nanomaterials sintered at elevated temperatures were investigated by depth sensitive positron annihilation studies on a variable energy slow positron beam. It was found that sintering causes intensive grain growth and residual porosity is removed from samples by diffusion to the surface.


2021 ◽  
Vol 11 (3) ◽  
pp. 1197
Author(s):  
Leandro Sottili ◽  
Laura Guidorzi ◽  
Anna Mazzinghi ◽  
Chiara Ruberto ◽  
Lisa Castelli ◽  
...  

At present, the use of non-destructive, non-invasive X-ray-based techniques is well established in heritage science for the analysis and conservation of works of art. X-ray fluorescence (XRF) plays a fundamental role since it provides information on the elemental composition, contributing to the identification of the materials present on the superficial layers of an artwork. Whenever XRF is combined with the capability of scanning an area to provide the elemental distribution on a surface, the technique is referred to as macro X-ray fluorescence (MA-XRF). The heritage science field, in which the technique is extensively applied, presents a large variety of case studies. Typical examples are paintings, ceramics, metallic objects and manuscripts. This work presents an uncommon application of MA-XRF analysis to furniture. Measurements have been carried out with the MA-XRF scanner of the INFN-CHNet collaboration at the Centro di Conservazione e Restauro “La Venaria Reale”, a leading conservation centre in the field. In particular, a chinoiserie lacquered cabinet of the 18th century and a desk by Pietro Piffetti (1701–1777) have been analysed with a focus on the characterisation of decorative layers and different materials (e.g., gilding in the former and ivory in the latter). The measurements have been carried out using a telemeter for non-planar surfaces, and with collimators of 0.8 mm and 0.4 mm diameter, depending on the spatial resolution needed. The combination of the small measuring head with the use of the telemeter and of a small collimator has guaranteed the ability to scan difficult-to-reach areas with high spatial resolution in a reasonable time (20 × 10 mm2 with 0.2 mm step in less than 20 min).


Holzforschung ◽  
2009 ◽  
Vol 63 (5) ◽  
Author(s):  
David Mannes ◽  
Walter Sonderegger ◽  
Stefan Hering ◽  
Eberhard Lehmann ◽  
Peter Niemz

Abstract Diffusion processes in samples of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies [L.] Karst.) were determined and quantified by means of neutron imaging (NI). The experiments were carried out at the neutron imaging facility NEUTRA at the Paul Scherrer Institute in Villigen (Switzerland) using a thermal neutron spectrum. NI is a non-destructive and non-invasive testing method with a very high sensitivity for hydrogen and thus water. Within the scope of this study, diffusion processes in the longitudinal direction were ascertained for solid wood samples exposed to a differentiating climate (dry side/wet side). With NI it was possible to determine the local distribution and consequently the total amount of water absorbed by the samples. The calculated values scarcely differ from those ascertained by weighing (≤3%). The method yields profiles of the water content over the whole sample, thus allowing the local and temporal resolution of diffusion processes within the sample in the main transport direction (longitudinal). On the basis of these profiles, it was possible to calculate the diffusion coefficients along the fibre direction according to Fick's second law.


2021 ◽  
Author(s):  
Benedek Bozóky ◽  
Carlos Fernández Moro ◽  
Carina Strell ◽  
Ingemar Ernberg ◽  
Laszlo Szekely ◽  
...  

AbstractPancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid tumors. Based on transcriptomic classifiers, basal-like and classical PDAC subtypes can be defined that differ in prognosis. Single-cell sequencing has recently revealed that these subtypes coexist in individual tumors. However, the contribution of either clonal heterogeneity or microenvironmental cues to subtype heterogeneity is unclear. Here, we report the tumor phenotype dynamics in a cohort of patients in whom PDAC infiltrated the duodenal wall. Using multiplex immunohistochemistry, we show that PDAC cells revert to non-destructive growth and undergo differentiation towards the classical subtype upon integration into the duodenal epithelium. Our results tightly link microenvironmental cues to the PDAC molecular subtype and open the door to a systematic investigation of microenvironmental control in human pancreatic cancer.


2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Rose King ◽  
Josep Grau-Bové ◽  
Katherine Curran

AbstractPlasticiser loss is a topic frequently mentioned in discussions on the degradation of plastic artefacts in museum collections, particularly for plasticised poly (vinyl chloride) and cellulose acetate. Plasticisers may migrate to the plastic’s surface and remain as a deposit, or volatilise into the surrounding environment, both presenting an aesthetic issue and impacting the future stability of the plastic. This paper draws on the work of conservation science, materials degradation, and indoor air quality/emissions studies, to review our current understanding of plasticiser loss. The influence of the material’s intrinsic properties, and environmental factors on migration rates are discussed and related to preventive conservation practices. The methods by which plasticiser migration is studied, including characterisation, are also reviewed, with a particular focus on minimally invasive and non-destructive methods suitable for heritage science research.


1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.


Author(s):  
B. B. Rath ◽  
J. E. O'Neal ◽  
R. J. Lederich

Addition of small amounts of erbium has a profound effect on recrystallization and grain growth in titanium. Erbium, because of its negligible solubility in titanium, precipitates in the titanium matrix as a finely dispersed second phase. The presence of this phase, depending on its average size, distribution, and volume fraction in titanium, strongly inhibits the migration of grain boundaries during recrystallization and grain growth, and thus produces ultimate grains of sub-micrometer dimensions. A systematic investigation has been conducted to study the isothermal grain growth in electrolytically pure titanium and titanium-erbium alloys (Er concentration ranging from 0-0.3 at.%) over the temperature range of 450 to 850°C by electron microscopy.


Author(s):  
J W Steeds

There is a wide range of experimental results related to dislocations in diamond, group IV, II-VI, III-V semiconducting compounds, but few of these come from isolated, well-characterized individual dislocations. We are here concerned with only those results obtained in a transmission electron microscope so that the dislocations responsible were individually imaged. The luminescence properties of the dislocations were studied by cathodoluminescence performed at low temperatures (~30K) achieved by liquid helium cooling. Both spectra and monochromatic cathodoluminescence images have been obtained, in some cases as a function of temperature.There are two aspects of this work. One is mainly of technological significance. By understanding the luminescence properties of dislocations in epitaxial structures, future non-destructive evaluation will be enhanced. The second aim is to arrive at a good detailed understanding of the basic physics associated with carrier recombination near dislocations as revealed by local luminescence properties.


Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).


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