Analysis of paintings from the nineteenth century Brazilian painter Rodolfo Amoedo using EDXRF portable system

The pigments used in four of the most representative paintings of the Brazilian artist Rodolfo Amoedo were characterized by means of the EDXRF technique. The analyzed paintings were ‘The Last Tamoyo’ (1883), ‘Study of a Woman’ (1884), ‘Bust of Mrs. Amoedo’ (1892) and ‘Bad News’ (1895). EDXRF measurements were carried out with a portable system developed by the Nuclear Instrumentation Laboratory, consisting of an x‐ray tube Oxford TF3005 with a W anode, operating at 25 kV and 100 µA, and a Si‐PIN XR‐100CR detector from Amptek. Several spectra were obtained in each color and distinct hue of the paint layer, with an acquisition time of 300 s and a beam collimation of 2 mm. Some pigments used by the artist were zinc white, lead white, ochre, umber, vermilion, Prussian blue, cobalt blue, cadmium yellow, black iron oxide and manganese violet. In the painting ‘The Last Tamoyo’, titanium white was identified in some alteration areas, which were restored during the twentieth century. These results—together with computed radiography analyses—will be used to create a database about the nineteenth‐century collection of the National Museum of Fine Arts, in order to assist restorers, conservators, art students and researchers in the field of archeometry. Copyright © 2009 John Wiley & Sons, Ltd.     

Photorefractive half-adder: beam-fanning for optical generation of ‘SUM’ and ‘CARRY’

Optical implementation of an adder of arithmetic units that processes binary numbers is outlined. Dynamic range compression using biasing illumination in beam-fanning geometry as observed in a photorefractive BaTiO₃:Fe crystal forms the underlying principle of operation. By proper choice of polarization for two input signals, XOR and AND operations are realized. These two operations are essentially analogous to SUM and CARRY generation for binary addition. By providing shift (only in case of CARRY) and feedback, experimental results for half-adder are obtained. In addition, the technique forms a very simple way of implementing ‘original carries’ as required for full-adder. The geometry proposed is simple, energy-efficient and can be easily extended to multi-wavelength operations thus achieving spectral parallelism in optical domain.     

Comparison of ‘blue’ and ‘infrared’ emission bands in thermoluminescence of alkali feldspars

Dating quaternary sediments by thermoluminescence (TL) or optically stimulated luminescence (OSL) calls for a detailed knowledge of the luminescence of feldspars. TL of the various alkali feldspars ((K, Na) Si₃AlO₈) display many common features, and some of these cause great difficulties for dating. After long storage following ionizing irradiation, the TL of most alkali feldspars is known to fade away by “anomalous fading”, which is incompatible with dating. This effect had been attributed to tunnel recombination. Following irradiation, a very intense tunnelling afterglow is observed at temperatures down to liquid nitrogen, in accordance with the observed rate of fading. This emission has a Gaussian spectrum entirely in the infrared (IR) with a maximum at 1.7 eV. It displays an important thermal quenching from 77 to 300 K. Its intensity is related with the ‘disorder’ of the crystal lattice. At higher temperatures, in TL proper, two emission bands can be separated. One is the well-studied complex visible emission, distributed over the spectral region from UV to orange, but mostly ‘blue’. The other is the ‘infrared’ band already observed at lower temperatures, which is attributed to Fe³⁺ ions. These two bands are clearly separated, with the spectral maxima, respectively, below and above 600 nm. They have also different kinetics, the glow peaks temperatures are different. But these two different bands are also coupled in many ways, they have parallel growth and fading. With ‘disordered’ feldspars, the ‘blue’ emission displays anomalous fading, which is stronger than that of the ‘infrared’. The infrared emission is more stable, which may be interesting for the purpose of dating.     

Technological features of ‘gnathia’ pottery

‘Gnathia’ pottery samples, dating back to the mid‐fourth and third century BC, from the archaeological site of Egnazia (Fasano, Brindisi, Italy) have been characterised from the physical‐chemical, mineralogical and morphological points of view. Optical and scanning electron microscopy, X‐ray energy‐dispersive spectroscopy and X‐ray diffraction analyses have been carried out on the ceramic body, black gloss, white, yellow and red over‐paintings of fragments, with the aim of outlining technological features and defining the nature of coatings and decorations. Analytical results confirm from both a technological and morphological/decorative point of view the close relationship between ‘Gnathia’ pottery and red figured pottery, particularly with the Apulian red figured from which it takes its inspiration. At the same time the experimental results highlight shared characteristics and differences with both Attic and Apulian red figured productions. The biggest difference is in the utilisation of the ‘ingobbio rosso’ layer that covers the ceramic body. This does not seem to be based on aesthetic grounds, as in the case of Apulian red figured pottery, but on application of acquired production processes, since ‘Gnathia’ pottery was made in the same workshops as red figured pottery. Copyright © 2009 John Wiley & Sons, Ltd.     

Constructing ‘hair’ for the three charge hole

It has been found that the states of the 2-charge extremal D1–D5 system are given by smooth geometries that have no singularity and no horizon individually, but a ‘horizon’ does arise after ‘coarse-graining’. To see how this concept extends to the 3-charge extremal system, we construct a perturbation on the D1–D5 geometry that carries one unit of momentum charge P. The perturbation is found to be regular everywhere and normalizable, so we conclude that at least this state of the 3-charge system behaves like the 2-charge states. The solution is constructed by matching (to several orders) solutions in the inner and outer regions of the geometry. We conjecture the general form of ‘hair’ expected for the 3-charge system, and the nature of the interior of black holes in general.     

Unfamiliar integrals and motions down the ‘plug-hole’ potential

The orbits in the potentials ψ=−CzR⁻²+ζ(R), (ζ arbitrary) have integrals E, and . Thus the z-velocity is proportional to the number of turns made around the axis! The Poisson Bracket [h,I] is not zero so Liouville’s integrability theorem does not apply. Starting from the self-similar potential with ζ∝R⁻¹, we find some orbits that spiral around cones and explore general orbits in this strange system.     

The concentration effect on the ‘hydrophobic’ and ‘hydrophilic’ behaviour around DMSO in dilute aqueous DMSO solutions. A computer simulation study

We have carried out a molecular dynamics study of dimethyl sulfoxide (DMSO) in water at 298 K at two different densities by simulating two different concentrations: 0.055 and 0.19 mole fraction. We have found an enhancement in the structure of water, an effect that becomes more pronounced as the concentration of DMSO increases. At both concentrations there is a well-defined hydration structure around the oxygen atom of DMSO, which is able to establish strong hydrogen bonds with surrounding water molecules. An increase in the concentration of DMSO depletes the solution of bulk water molecules, reducing the number of hydrogen bonds that water can have in the immediate vicinity of DMSO but increasing the strength of the hydrogen bonds made between the oxygen atom of DMSO and water. There is clear evidence of ‘hydrophobic’ hydration around the methyl groups of DMSO, which is enhanced as the concentration of DMSO increases.     

Spectroscopic investigation of modern pigments on purportedly medieval miniatures by the ‘Spanish Forger’

Five miniatures by the so‐called ‘Spanish Forger’ were acquired by the Victoria and Albert Museum in 2008. Believed to be authentic medieval miniatures until the mid‐twentieth century, they are now considered to have been painted around the end of the nineteenth and the beginning of the twentieth century. To investigate this attribution and to gather detailed knowledge about the materials used by the artist, a comprehensive pigment analysis by Raman microscopy and X‐ray fluorescence was carried out. Although traditional materials such as vermilion, carbon black, red lead, lead white and indigo were identified, many others (chrome yellow, Scheele's green, emerald green and ultramarine blue) are modern and synthetic pigments, a result which provides a firm scientific basis for stating that the miniatures are forgeries. Copyright © 2009 John Wiley & Sons, Ltd.     

Predicting ‘lifetime’ of fibre optics exposed to radiation

Fibre optics communications systems are rapidly replacing ‘wired’ links in a variety of applications. The fibre links have proven to be smaller and lighter than either simple wire or coaxial lines. In addition, the fibre systems are immune to all forms of electrical interference (RFI; EMI; static electricity, etc.). Because of the very nature of the passive fibre lines, electrical disturbances may be considered as part of a benign environment, as contrasted with a hostile counterpart, such as high-energy particle fields which are prevalent in a nuclear reactor or other radiation-producing machine. It is known that nuclear radiation may damage the optical transmission properties of fibre optics waveguides. Described herein is the relationship between radiation flux and subsequent damage to the fibre waveguides. Some data, curves and calculations and supporting references are presented. And, finally, a procedure is given as an aid to predicting the ‘lifetime’ of a fibre optics link when it is exposed to the damaging effects of radiation.     

Enhanced gauge symmetry from ‘toric’ G2 cones

We discuss the construction of M‐theory compactifications on ‘toric’ G₂ cones, a class of models which generalize those recently considered by Acharya and Witten. We explain our criteria for identifying the gauge group content of such theories and briefly discuss the associated metrics.     

Is the ‘Finite Bias Anomaly’ in planar GaAs-superconductor junctions caused by point-contact-like structures?

We correlate transmission electron microscope (TEM) pictures of superconducting In contacts to an AlGaAs/GaAs heterojunction with differential conductance spectroscopy performed on the same heterojunction. Metals deposited onto a (100) AlGaAs/GaAs heterostructure do not form planar contacts, but, during thermal annealing, grow down into the heterostructure along crystallographic planes in pyramid-like ‘point contacts’. Random surface nucleation and growth gives rise to a different interface transmission for each superconducting point contact. Samples annealed for different times, and therefore having different contact geometry, show variations in dI / dV characteristics of ballistic transport of Cooper pairs, wave interference between different point emitters, and different types of weak localization corrections to Giaever tunneling. We give a possible mechanism whereby the ‘finite bias anomaly’ of Poirier et al. [Phys. Rev. Lett. 79, 2105 (1997)], also observed in these samples, can arise by adding the conductance of independent superconducting point emitters in parallel.     

‘Locking and unlocking control’ of photochromism of naphthopyran derivative

A ‘locking and unlocking control’ for a photochromic molecular system has been developed by using a photochromic naphthopyran derivative 1a as the model compound. With UV light irradiation, the colorless solution of 1a underwent ring‐opening photoisomerization and converted to a purple solution 1b , which quickly faded back to a colorless solution with visible light (λ ≥ 480 nm) irradiation or in the dark. Addition of boron trifluoride diethyl etherate to the solution of 1b produced a complex compound 2b , accompanying the color change from purple to blue. It was found that 2b remained photochemically inactive. With the addition of diethanolamine, however, the ‘locked’ photoreaction of 2b could be unlocked and converted back to 1b , in which the photochromism was recovered. Copyright © 2009 John Wiley & Sons, Ltd.     

Electron interaction and ‘memory’ effects in the presence of mixed disorder

We have studied the effect of electron–electron interaction in the presence of mixed disorder on the conductivity and Hall effect of a high-mobility two-dimensional electron gas in a GaAs/AlGaAs heterostructure. A parabolic, negative, temperature-dependent magnetoresistance (MR) and temperature-dependent Hall effect are observed. We show that these effects can be explained in terms of the interaction theory. In addition, a temperature independent, positive MR is observed. This classical MR is also shown to be a consequence of the mixed disorder.     

Determination of absorption correction by the ‘two masses’ method for XRF analysis of intermediate samples

A simple method for the determination of the absorption correction for intermediate samples is presented. This method consists in measurements of the intensity of radiation of an analyte element in two samples with different masses per unit area and with identical composition. The absorption correction can be determined for samples loaded on the thin or thick substrate or without substrate in the same way. The results obtained are compared with those given by an emission–transmission method with the use, as an example, of synthetic samples pressed into pellets. The absorption correction was also determined for geological samples collected on a filter mounted on a thick substrate. A simple apparatus for collecting powder material on the filter is presented. Copyright © 2003 John Wiley & Sons, Ltd.     

Reconstruction of an acoustical image using an ‘acousto-electronic’ lens device

Present acoustic imaging apparatuses give only a virtual image of the insonified object. Several studies have been conducted in order to pick up the information from such an image, such as holography and computer data processing. These techniques are very involved, and so simpler processing systems have been analysed in our laboratory in order to reconstruct a true image. Our first system used optical processing of the acoustic echo. In this paper, a second, acousto-electronic, system is described, which enables like the first the attainment of very high image rates in the B-scan mode.     

Extending the age range of optical dating using single ‘supergrains’ of quartz

Luminescence dating methods have been used to obtain reliable age estimates for quartz sediments deposited within the last 500 ka, but it has proven difficult to extend the age range much beyond this limit. Here we report the results of a study of individual quartz grains from Australian sedimentary deposits that range in age from 250 to 950 ka. A small number of the grains examined are strongly luminescent and saturate at unusually high doses. These ‘supergrains’ may permit reliable age determination to 1 Ma, and possibly beyond. Some other grains are in, or close to, dose-saturation, so that only minimum age estimates may be obtained. Most of the grains examined are very weakly luminescent and have palaeodoses much less than expected, while the palaeodoses of some grains cannot be estimated because of anomalous dose–response characteristics. We offer some possible explanations for the behaviour of aberrant grains.     

Micro‐Raman and stratigraphic studies of the paintings on the ‘Cembalo’ model musical instrument (A.D. 1650) and laser‐induced degradation of the detected pigments

Micro‐fragments of the painted part of the ‘Cembalo’ model by Michele Todini (1625–1689) are investigated. The technique used for painting the terracotta base was studied via the stratigraphic analyses. No background layer of inorganic materials, e.g. gypsum, was found. To prevent absorption effects due to the terracotta porosity, a very thin layer of proteinaceous material was probably used. The micro‐Raman analyses have revealed the use of pigments currently used in the post‐Renaissance period (lead white, indigo, yellow of iron hydroxide, gypsum, hematite and carbon black) mixed with a pigment, the Prussian blue, discovered in A.D . 1704. This raises the authenticity problem of the work of art, a problem analysed and discussed in presenting the history of the work of art, and after the pigment study. The presence of degraded lead white is recognized via the laser‐induced degradation of the irradiated material. The possibility of a restoring action of the painted parts, as opposite to the non‐originality of the work, is considered and discussed. Since most part of the investigated pigments shows laser‐induced effects, a careful study of this phenomenon is performed by using the modern counterparts of the ancient pigments. For different laser powers, the temperatures of the investigated zones have been obtained via the detailed balance principle and connected to the laser‐induced degradation effects. Copyright © 2007 John Wiley & Sons, Ltd.     

In situ energy dispersive X‐ray fluorescence analysis of rock art pigments from the ‘Abrigo dos Gaivões’ and ‘Igreja dos Mouros’ caves (Portugal)

A portable energy dispersive X‐ray fluorescence spectrometer was used to obtain the elemental composition of Neolithic rock art paintings of the ‘Abrigo dos Gaivões’ and ‘Igreja dos Mouros’ caves. These caves, located in the Esperança parish, Arronches' county, in the San Mamede's mountains (Portugal), belong to a group of spread shelters just next to the western Spanish border. Results show the strong presence of iron in bare rock, and this element can be clearly detected as the main component of the red paintings. No evidence of manganese was detected in either the brownish or the black paintings, contrary to other Neolithic paintings in the Mediterranean area. Copyright © 2011 John Wiley & Sons, Ltd.