R.C. Barroso

X-ray diffraction microtomography using synchrotron radiation

Abstract The X-ray diffraction computed tomography technique is based on the interference phenomena of the coherent scatter. For low-momentum transfer, it is most probable that the scattering interaction will be coherent. A selective discrimination of a given element in a scanned specimen can be realized by fixing the Bragg angle which produces an interference peak and then, to carry out the computed tomography in the standard mode. The image reconstructed exalts the presence of this element with respect to other ones in a sample. This work reports the feasibility of a non-destructive synchrotron radiation X-ray diffraction imaging technique. This research was performed at the X-ray Diffraction beam line of the National Synchrotron Light Laboratory (LNLS) in Brazil. The coherent scattering properties of different tissue and bone substitute materials were evaluated. Furthermore, diffraction patterns of some polycrystalline solids were studied due to industrial and environmental human exposure to these metals. The obtained diffraction patterns form the basis of a selective tomography technique. Preliminary images are presented.

Elemental mapping of teeth using μSRXRF

Human teeth were analysed by X-ray microfluorescence analysis using synchrotron radiation (μSRXRF). The aim of this work was to study the elemental distribution for Ca, Zn and Sr along the dental regions, enamel, dentine and pulp from patterns of relative fluorescence intensities. The measurements were performed in standard geometry of 45° incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The results show that Ca distribution is quite constant and it is independent of the tooth type and individuals characteristics. An increase of the Zn concentration was found for the pulp region and for untreated carious areas. Ca and Sr distributions show a similar behavior.

Novel Orally Active Analgesic and Anti-Inflammatory Cyclohexyl-N-Acylhydrazone Derivatives

The N-acylhydrazone (NAH) moiety is considered a privileged structure, being present in many compounds with diverse pharmacological activities. Among the activities attributed to NAH derivatives anti-inflammatory and analgesic ones are recurrent. As part of a research program aiming at the design of new analgesic and anti-inflammatory lead-candidates, a series of cyclohexyl-N-acylhydrazones 10–26 were structurally designed from molecular modification on the prototype LASSBio-294, representing a new class of cycloalkyl analogues. Compounds 10–26 and their conformationally restricted analogue 9 were synthetized and evaluated as analgesic and anti-inflammatory agents in classical pharmacologic protocols. The cyclohexyl-N-acylhydrazones 10–26 and the cyclohexenyl analogue 9 showed great anti-inflammatory and/or analgesic activities, but compound 13 stood out as a new prototype to treat acute and chronic painful states due to its important analgesic activity in a neuropathic pain model.

3D histomorphometric quantification of trabecular bones by computed microtomography using synchrotron radiation.

Conventional bone histomorphometry is an important method for quantitative evaluation of bone microstructure. X-ray computed microtomography is a non-invasive technique, which can be used to evaluate histomorphometric indices in trabecular bones (BV/TV, BS/BV, Tb.N, Tb.Th, Tb.Sp). In this technique, 3D images are used to quantify the whole sample, differently from the conventional one, in which the quantification is performed in 2D slices and extrapolated for 3D case. In this work, histomorphometric quantification using synchrotron 3D X-ray computed microtomography was performed to quantify the bone structure at different skeletal sites as well as to investigate the effects of bone diseases on quantitative understanding of bone architecture. The images were obtained at Synchrotron Radiation for MEdical Physics (SYRMEP) beamline, at ELETTRA synchrotron radiation facility, Italy. Concerning the obtained results for normal and pathological bones from same skeletal sites and individuals, from our results, a certain declining bone volume fraction was achieved. The results obtained could be used in forming the basis for comparison of the bone microarchitecture and can be a valuable tool for predicting bone fragility.

X-ray fluorescence with synchrotron radiation to elemental analysis of lead and calcium content of primary teeth.

Primary teeth were analyzed by micro-SRXRF. The aim of this study was to determine the elemental distribution of lead and calcium in different regions of primary incisor of children living in a notoriously contaminated area (Santo Amaro da Purificação, Bahia State, Brazil). The measurements were performed in standard geometry of 45 degrees incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil).

X-RAY DIFFRACTION TOMOGRAPHY USING INTERFERENCE EFFECTS

Abstract When the electromagnetic wave excites more than one electron, the coherent scatter from different electrons gives rise to interference effects. X-rays scattered from a crystalline solid can constructively interfere, producing a diffracted beam at well-defined Bragg angles. The aim of this work is to describe a new imaging method based on the detection of diffracted X-rays. Diffraction patterns of polycrystalline solids (lead, silver and copper) were measured. A selective discrimination of a given element in a scanned specimen can be realized by fixing the Bragg angle which produces an interference peak and then, to carry out the computed tomography in the standard mode. The images obtained show the feasibility of this selective tomography

Anatomical variations in primary teeth microelements with known differences in lead content by micro-Synchrotron Radiation X-Ray Fluorescence (μ-SRXRF) – A preliminary study

Shed teeth have been proposed as trace element biomarkers. This study determined variations in the spatial distribution of Ca, K, Zn, Pb, Mn, Cu, and Sr in four anatomical locations: superficial enamel (SE, 0-10μm), subsuperficial enamel (SSE, 10-30μm), primary dentin (PD), and secondary dentin (SD). Five primary incisors were analyzed by micro Synchrotron Radiation X-Ray Fluorescence (μ-SRXRF). Two teeth had low concentrations of lead in the SE (<250μg/g), while three contained very high lead concentrations in the SE (>2000μg/g). Teeth were sliced, and five spot measurements (20μm beam diameter) were accomplished in each location. The data are shown as absolute values and as the ratio between the different elements and Ca. The distribution of K was close to that of Ca. Zn was the third most abundant element, with the highest levels being found in the SE and SD and low levels detected in the PD. Increasing Sr levels were found progressing from the enamel to the dentin, with the highest levels being found in the SD, a distribution that was unique. Pb, Mn, and Cu exhibited a similar trend, with higher signals for these elements detected in the SE. This study provides preliminary data on the heterogeneous distribution of different elements in the tooth, highlighting the importance of the first 10μm of the SE for determination of some elements, such as Zn, Pb, Mn, and Cu.

Heavy Metals in Groundwater using Synchrotron Radiation Total Reflection X-Ray Analysis

Abstract The environmental pollution problem has increased due to industrial and population growth. São Paulo and Campinas are examples of large urban centers that have grown in a disorderly manner and, today, present contamination problems which have also reached the groundwater. In order to obtain information about levels of heavy metals in groundwater, analyses were carried out with samples from well monitoring at Landfill Pirelli in Campinas and in some supplying wells in the Campinas region which are, in their majority, wells of industrial supply. The analytical technique used for achievement of the analysis is total reflection X‐ray fluorescence with synchrotron radiation. All measurements were performed at Synchrotron Light Source Laboratory, located in Campinas, São Paulo, Brazil. The determined elements in this research were Al, Fe, Mn, Cu, Cr, Ni, Zn, Ba, and Pb. The results were compared with the maximum permitted values (MPV) established by the Brazilian Health Department and, for Landfill Pirelli, the concentrations were higher than the permitted values for Ba and Pb, as was expected, because this landfill received residues during many years without control. In well supply, as in State University of Campinas (UNICAMP), elements such as Cr and Pb were not expected, so the monitoring of these wells is necessary in order to verify if these elements continue to be detected with values above the permitted values. The same elements were also detected in other supplying wells in the Campinas metropolitan region. For lead (Pb), values above the maximum were observed in 15 wells. The detection limits obtained varyied from 0.10 µg · L−1 to 7.91 µg · L−1 and were in agreement with the values presented by other analytical techniques.

X-ray transmission microtomography using synchrotron radiation

This work reports the feasibility of a non-destructive synchrotron radiation X-ray transmission imaging technique development at Brazilian synchrotron light source. The quality control image parameters (spatial and density resolution and noise) are given and microtomograms presented. Microtomograms of biomedical samples are presented. The tomography system was mounted into the XRF beamline that uses a high-intensity white beam with 12 keV effective energy, and maximum width and height equals to 11 and 1 mm, respectively. The detector used to collect the data was a 512-pixel Hamamatsu linear array with width of 50 μm (36 μm of sensitivity length) and cooled by a Peltier junction, causing the temperature falling down to 15°C. The samples were placed over a computer controlled table with 0.5° angular resolution and turned around the center covering 360°. To reconstruct the sample a parallel beam filtered back-projection algorithm was used.

Structural feature evolution – from fluids to the solid phase – and crystal morphology study of LASSBio 1601: a cyclohexyl-N-acylhydrazone derivative

LASSBio-1601, a cyclohexyl-N-acylhydrazone derivative, was synthesized as part of a research program to develop a series of anti-inflammatory and analgesic compounds. A complete knowledge of the structure, including stereochemistry, is essential to lead optimization in drug discovery. In this work different techniques were used to obtain detailed information on the evolution of the structural characteristics of this compound from fluids to the solid state, in order to shed some light on the conformation of the molecule in different physical states. By quoting the aforementioned structural analysis, a crystal morphology prediction, compared with the experimentally inferred SEM images, has been performed to analyze potentially alternative routes useful for pharmaceutical tableting.