Abstract: The energy distributions of ions produced in a spark source mass spectrometer were recorded for different trace element ions and for the total ion current. Both electrodes of pure doped graphite, and with 10% potassium salts added, were examined. The results show that the measured energy of an ion is mainly determined by the m/z ratio and that the energy of the total ion current depends on the sample composition. It was also clear that if the accelerating voltage is set to obtain maximum transmission of the total ion current, the fraction of the heavy elements that is discriminated at the β-slit depends on the matrix composition if the pass band of the instrument is narrow. These effects influence considerably the accuracy in the analysis of variable samples.

Abstract: Spark source mass spectrometric analyses of doped carbon samples were performed at different pulse lengths, pulse frequencies and breakdown voltages. The pulse length and pulse frequencies had no influence on the analysis. The relation between breakdown voltage, spark gap and sample matrix was determined. With increasing breakdown voltage, the abundance of the multiply charged ions was found to decrease, whereas the abundance of the cluster ions increased. The breakdown voltage was also found to affect the absolute and relative intensities of different elements in different manners. Interpretation of these results led to some new considerations on the phenomena in a spark discharge.

Abstract: The integration of the nonlinear least squares X-ray spectrum evaluation progam AXIL. into a mu-PIXE and a mu-XRF setup is discussed. The use of the software when procesing data sets derived from biological and geological samples is described.

Abstract: An important part of the European cultural heritage is composed of hand-written documents. Many of these documents were drawn up with iron-gall ink. This type of ink present a serious conservation problem, as it slowly oxidizes ('burns') the paper it is written on, thereby gradually disintegrating the historic document. Acid hydrolysis of the cellulose and/or the oxidation of organic compounds promoted by radical intermediates that are formed due to the presence of Fe2+ ions are considered to be the cause of the disintegration. mu-XANES measurements were performed with a lateral resolution of 30-50 mum in order to determine the local Fe2+/Fe3+ ratio in 19th C. documents from the Austrian National Archives and fragments of 16th C documents from the Polish National Library. In the 19th C documents, no significant amount of Fe2+ was detected. On the other hand, in the 16th C fragments, significant amounts of Fe2+ and appreciable differences in distribution of Fe2+ and Fe3+ within individual letters/ink stains were observed. (C) 2003 Elsevier B.V. All rights reserved.

Abstract: The radiation damage, in terms of atom displacements, induced by gamma irradiation in LYSO and LuYAP crystals is presented. Sc-44, Na-22 and V-48 are used as gamma sources for this study. The energy of gammas from the electron positron annihilation processes (511 keV) is also included in the study. The atom displacements distributions inside each material are calculated following the Monte Carlo assisted Classical Method introduced by the authors. This procedure also allows to study the atom displacements in-depth distributions inside each crystal. The atom displacements damage in LYSO crystals is found to be higher than in LuYAP crystals, mainly provoked by the displacements of silicon and oxygen atoms. But the difference between atom displacements produced in LYSO and LuYAP decreases when more energetic sources are used. On the other hand, the correlation between the atom displacements and energy deposition in-depth distributions is excellent. The atom displacements to energy deposition ratio is found to increases with more energetic photon sources. LYSO crystals are then more liable to the atom displacements damage than LuYAP crystals. (C) 2015 Elsevier B.V. All rights reserved.

Abstract: An approach using optical data to simulate both the bremsstrahlung continuum and characteristic K and L X-ray lines generated by low energy electrons (cfr. electron microscopy) in solids is discussed in this paper. The necessary analytical expressions together with the data to calculate the relevant cross sections for elastic and inelastic interactions at these energies along with variance reduction techniques are given. The results of the Monte Carlo simulation are compared to experimental data measured with a JEOL 6300 electron microscope.

Abstract: The Monte Carlo assisted Classical Method (MCCM) consists on a calculation procedure for determining the displacements per atom (dpa) distribution in solid materials. This algorithm allows studying the gamma and electron irradiation damage in different materials. It is based on the electrons elastic scattering classic theories and the use of Monte Carlo simulation for the physical processes involved. The present study deals with the Monte Carlo simulation of electron irradiation effects on YBa2Cu3O7-x (YBCO) slabs using the MCNPX code system. Displacements per atom distributions are obtained through the MCCM for electron irradiation up to 10 MeV. In-depth dpa profiles for electrons and positrons are obtained and analysed. Also, dpa contributions from each atomic specie in the material are calculated. It was found that the dpa distribution is more homogeneous in the material volume when increasing energy of incident electrons. Also, the dpa produced by positrons has no relevance when irradiating with electrons, in contrast with previous similar gamma irradiation studies. All the results are presented and discussed in this contribution. (C) 2011 Elsevier B.V. All rights reserved.

Abstract: Determination of count losses and pile-up pulse effects in quantitative and qualitative analysis became a vital step in various analyses. Therefore, compensating for counting losses is of importance. These counting losses are due to the pulse pile-up, paralyzable and non-paralyzable system dead time or a combination of these mechanisms. In this work, a new method is suggested for the correction of dead time losses resulting from the above mechanisms. For this purpose, a source code was developed. It was found that the peaking time was an important parameter over system dead time. The method suggested seems to be more effective even at high count rate. (C) 2009 Elsevier B.V. All rights reserved.

Abstract: To produce effective thermoelectric nanocomposites, carbon nanofibers (CNF) incorporated polyurethane (PU) foams with nanocomposites are prepared via in-situ polymerization method to create a synergy that would produce a high thermopower. The formation mechanism of foams, the reaction kinetics, and the physical properties such as density and water absorption studied before and after CNF incorporation. The microscopy images showed a uniform dispersion of CNF in the PU matrix of the prepared foams. Spectroscopic studies such as X-ray photoelectron and laser Raman spectroscopy suggested the existence of a tight intermolecular binding interaction between the carbon nanofibers and the PU matrix in the prepared composite foams. It found that the thermopower is directly dependent on the concentration of carbon nanofiber since, with rising concentration of 1%3%, the coefficient values increased from 1.2 μV/K to 11.9 μV/K respectively, a value higher than that of earlier report. This unique nanocomposite offers a new opportunity to recycle waste heat in portable/wearable electronics and other applications, which will broaden the development of low weight and mechanical flexibility.

Abstract: A new method to estimate case specific prediction uncertainty for univariate trilinear partial least squares (tri-PLS1) regression is introduced. This method is, from a theoretical point of view, the most exact finite sample approximation to true prediction uncertainty that has been reported up till now. Using the new method, different error sources can be propagated, which is an advantage that cannot be offered by data driven approaches such as the bootstrap. In a concise example, it is illustrated how the method can be applied. In the Appendix, efficient algorithms are presented to compute the estimates required.

Abstract: Over the past several decades the painting An Old Man in Military Costume by Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246) has been the subject of a number of investigations carried out in order to better visualize a second painting beneath the surface figure. The underlying image – the head and shoulders of a man wearing a cloak – is oriented 180 degrees from the upper image and appears to be fairly complete. Scanning macro x-ray fluorescence (XRF) spectroscopy reveals the face is painted with lead white and a mercury-containing pigment (likely vermilion), and the cloak is painted with a copper-containing pigment. Following the revelation and digital color reconstruction of the underlying figure, a number of questions still remained. Here, through the use of infrared reflectance imaging spectroscopy (i.e., hyperspectral imaging) and macro-XRF imaging spectroscopy, together with cross-sections taken from targeted areas, the sequence of painting in both compositions was explored. Of particular interest was the discovery of evidence of multiple attempts to situate the lower figure, and the subsequent application of a blocking-out layer over the lower figure before the artist rotated the panel and executed the upper figure. In addition, examination of the placement of the two images on the panel adds to our understanding of the subtle complexities of Rembrandt's working process. RESUMEAu cours des dernieres decennies, la peinture Le vieil homme en costume militaire de Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246) a fait l'objet de nombreuses investigations menees dans le but de mieux visualiser une seconde peinture dissimulee sous la surface. L'image sous-jacente – la tete et les epaules d'un homme vetu d'une cape – est orientee a 180 degres de de l'image du vieil homme, et elle semble assez complete. La spectroscopie a macro-balayage de fluorescence X (MA-XRF) revele que le visage est peint avec du blanc de plomb et un pigment contenant du mercure (comme le vermillon), et que la cape est peinte avec un pigment a base de cuivre. Plusieurs questions restaient en suspens suite a cette decouverte et a la reconstruction numerique en couleur de l'image sous-jacente. Grace a l'emploi de techniques d'imagerie comme la spectroscopie proche infrarouge (ex., imagerie hyperspectrale) et l'imagerie MA-XRF, combinees a l'analyse de coupes stratigraphiques prelevees a des endroits cibles, on a pu explorer la sequence d'application des couches picturales de chacune des deux compositions. Une decouverte particulierement interessante est la preuve que l'artiste a fait plusieurs tentatives pour positionner la figure sous-jacente puis, a ensuite applique une couche pour la recouvrir completement avant de faire pivoter le panneau et peindre la figure du vieil homme. De plus, l'examen du positionnement des deux images sur le panneau ajoute a notre comprehension de la subtile complexite du processus de creation de Rembrandt. Traduit par Elisabeth Forest. RESUMONas ultimas decadas, a pintura Um Velho em Traje Militar, de Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246), foi objeto de uma serie de investigacoes realizadas para visualizar melhor uma segunda pintura abaixo da figura aparente. A imagem subjacente – a cabeca e os ombros de um homem usando uma capa – e orientada a 180 graus da imagem superior e parece estar bastante completa. O macro mapeamento de imagem por espectroscopia de fluorescencia de raios X (FRX) revela que a face e pintada com branco de chumbo e um pigmento contendo mercurio (provavelmente vermelhAo), e a capa e pintada com um pigmento contendo cobre. Apos a descoberta e reconstrucAo digital da cor da figura subjacente, uma serie de questoes ainda permanecem. EntAo, atraves da utilizacAo do mapeamento por imagem de espectroscopia de refletancia por infravermelhos (i.e. mapeamento hiperespectral) e macro mapeamento por imagem de FRX, juntamente com cortes estratigraficos de amostras retiradas de areas de interesse, a pintura em ambas as composicoes foi explorada. De particular interesse foi a descoberta de evidencias de multiplas tentativas de posicionar a figura subjacente, e a subsequente aplicacAo de uma camada intermediaria de separacAo sobre a figura inferior antes do artista girar o painel e executar a figura superior. Alem disso, o exame da colocacAo das duas imagens no painel aumenta nossa compreensAo das sutis complexidades do processo de trabalho de Rembrandt. Traduzido por Marcia Rozzi e Beatriz Haspo. RESUMENA lo largo de las ultimas decadas, la pintura Un anciano con traje militar de Rembrandt Harmensz van Rijn (ca. 1630-31; J. Paul Getty Museum, 78.PB.246) ha sido objeto de varias investigaciones realizadas con el fin de visualizar mejor una segunda pintura debajo de la figura de la superficie. La imagen subyacente, la cabeza y los hombros de un hombre que lleva una capa, esta orientada a 180 grados de la imagen superior y parece estar bastante completa. La espectroscopia de fluorescencia de rayos X (XRF) de barrido revela que la cara esta pintada con blanco de plomo y un pigmento que contiene mercurio (probablemente bermellon), y la capa esta pintada con un pigmento que contiene cobre. Tras la revelacion y la reconstruccion digital del color de la figura subyacente, aun quedaban algunas preguntas. Aqui, por medio del uso de la espectroscopia de imagenes de reflectancia infrarroja (es decir, imagenes hiperespectrales) e imagenes macro-XRF, junto con las secciones transversales tomadas de areas especificas, se exploro la secuencia de pintura en ambas composiciones. De particular interes fue el descubrimiento de evidencia de multiples intentos de situar la figura inferior, y la aplicacion posterior de una capa de bloqueo sobre la figura inferior antes de que el artista rotara el panel y ejecutara la figura superior. Ademas, el examen de la colocacion de las dos imagenes en el panel contribuye a nuestra comprension de las sutiles complejidades del proceso de trabajo de Rembrandt. Traduccion: Amparo Rueda.