Towards truly simultaneous PIXE and RBS analysis of layered objects in cultural heritage

For a long time, RBS and PIXE techniques have been used in the field of cultural heritage. Although the complementarity of both techniques has long been acknowledged, its full potential has not been yet developed due to the lack of general purpose software tools for analysing the data from both techniques in a coherent way. In this work we provide an example of how the recent addition of PIXE to the set of techniques supported by the DataFurnace code can significantly change this situation. We present a case in which a non homogeneous sample (an oxidized metal from a photographic plate -heliography- made by Niepce in 1827) is analysed using RBS and PIXE in a straightforward and powerful way that can only be performed with a code that treats both techniques simultaneously as a part of one single and coherent analysis. The optimization capabilities of DataFurnace, allowed us to obtain the composition profiles for these samples in a very simple way.Comment: 9 pages, 3 figure

Color tunable pressure sensors based on polymer nanostructured membranes for optofluidic applications

We demonstrate an integrated optical pressure sensing platform for multiplexed optofluidics applications. The sensing platform consists in an array of elastomeric on-side nanostructured membranes -effectively 2D photonic crystal- which present colour shifts in response to mechanical stress that alter their nanostructure characteristical dimensions, pitch or orientation. The photonic membranes are prepared by a simple and cost-effective method based on the infiltration of a 2D colloidal photonic crystal (CPC) with PDMS and their integration with a microfluidic system. We explore the changes in the white light diffraction produced by the nanostructured membranes when varying the pneumatic pressure in the microfluidics channels as a way to achieve a power-free array of pressure sensors that change their reflective colour depending on the bending produced on each sensor. The structural characterization of these membranes was performed by SEM, while the optical properties and the pressure-colour relation were evaluated via UV-Vis reflection spectrometry. Maximum sensitivities of 0.17 kPa is obtained when measuring at Littrow configuration (θ = −θ ), and close to the border of the membranes. The reflected colour change with pressure is as well monitorized by using a smartphone camera

Mechanochromic detection for soft opto-magnetic actuators

Altres ajuts: ICN2 is funded by the CERCA programme/Generalitat de Catalunya.New multi-stimuli responsive materials are required in smart systems applications to overcome current limitations in remote actuation and to achieve versatile operation in inaccessible environments. The incorporation of detection mechanisms to quantify in real time the response to external stimuli is crucial for the development of automated systems. Here, we present the first wireless opto-magnetic actuator with mechanochromic response. The device, based on a nanostructured-iron (Fe) layer transferred onto suspended elastomer structures with a periodically corrugated backside, can be actuated both optically (in a broadband spectral range) and magnetically. The combined opto-magnetic stimulus can accurately modulate the mechanical response (strength and direction) of the device. The structural coloration generated at the corrugated back surface enables to easily map and quantify, in 2D, the mechanical deflections by analyzing in real time the hue changes of images taken using a conventional RGB smartphone camera, with a precision of 0.05°. We demonstrate the independent and synergetic optical and magnetic actuation and detection with a detection limit of 1.8 mW·cm -2 and 0.34 mT, respectively. The simple operation, versatility, and cost-effectiveness of the wireless multiactuated device with highly sensitive mechanochromic mapping paves the way to a new generation of wirelessly controlled smart systems

Experimental determinatation of stopping forces for ions in matter

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Aplicada. Fecha de lectura: 12-11-2004The present work deals with the interaction of moving ions with matter. A strong emphasis is done on the methodological aspects of the experimental determination of stopping forces. The general objective of the work is to find a suitable method to platain stopping forces for ions in materials of practical interest for reseach ielated to ion beam analysis/modification of materials. Various combinations of ions and target materials have been investigated using already established methods and the experience gained from them helped to develop a new method with some very attractive characteristics from a practical perspective. The materials treated are mainly binary compounds with important technological applications (Si0 2 , Si3N4 and Al203 ), but also Mylar and gold. The ions investigated have been: 4He, 12C, 16u^ ,FA1, 28Si and 40Ar. - This document is also a memory of the fruits of more than four years of work, both in the stopping force research as in the participation in developing a completely new accelerator laboratory for ion beam analysis (the second in Spain and equipped with the largest accelerator). The evolution of this thesis and that of the accelerator run in parallel: both were mere projects in 1999 and both have been now completed —if a laboratory is ever complete—, being this the first thesis to see light from our young laboratory. The text is structured in three parts with three chapters each. The first part is devoted to establish the basic concepts that are used along the rest of the work. The second part describes the experimental setup of our laboratory as well as the experimental methods that are used for stopping force determination (those already existent and also the newly developed one). Finally, the third part shows the experimental results obtained along. the various sets of experiments performed

Improving data quality and expanding BioSAXS experiments to low-molecular-weight and low-concentration protein samples

The addition of compounds to scavenge the radical species produced during biological small-angle X-ray scattering (BioSAXS) experiments is a common strategy to reduce the effects of radiation damage and produce better quality data. As almost half of the experiments leading to structures deposited in the SASBDB database used scavengers, finding potent scavengers would be advantageous for many experiments. Here, four compounds, three nucleosides and one nitrogenous base, are presented which can act as very effective radical-scavenging additives and increase the critical dose by up to 20 times without altering the stability or reducing the contrast of the tested protein solutions. The efficacy of these scavengers is higher than those commonly used in the field to date, as verified for lysozyme solutions at various concentrations from 7.0 to 0.5 mg ml$^{−1}$. The compounds are also very efficient at mitigating radiation damage to four proteins with molecular weights ranging from 7 to 240 kDa and pH values from 3 to 8, with the extreme case being catalase at 6.7 mg ml$^{−1}$, with a scavenging factor exceeding 100. These scavengers can therefore be instrumental in expanding BioSAXS to low-molecular-weight and low-concentration protein samples that were previously inaccessible owing to poor data quality. It is also demonstrated that an increase in the critical dose in standard BioSAXS experiments leads to an increment in the retrieved information, in particular at higher angles, and thus to higher resolution of the model

Color tunable pressure sensors based on polymer nanostructured membranes for optofluidic applications

We demonstrate an integrated optical pressure sensing platform for multiplexed optofluidics applications. The sensing platform consists in an array of elastomeric on-side nanostructured membranes -effectively 2D photonic crystal- which present colour shifts in response to mechanical stress that alter their nanostructure characteristical dimensions, pitch or orientation. The photonic membranes are prepared by a simple and cost-effective method based on the infiltration of a 2D colloidal photonic crystal (CPC) with PDMS and their integration with a microfluidic system. We explore the changes in the white light diffraction produced by the nanostructured membranes when varying the pneumatic pressure in the microfluidics channels as a way to achieve a power-free array of pressure sensors that change their reflective colour depending on the bending produced on each sensor. The structural characterization of these membranes was performed by SEM, while the optical properties and the pressure-colour relation were evaluated via UV-Vis reflection spectrometry. Maximum sensitivities of 0.17 kPa is obtained when measuring at Littrow configuration (θ = −θ ), and close to the border of the membranes. The reflected colour change with pressure is as well monitorized by using a smartphone camera

Advanced fitting algorithms for analysing positron annihilation lifetime spectra

Abstract 2 The most common way to analyse PALS spectra involves fitting a parameter-dependent model to the experimental data. Traditionally, this fit involves local nonlinear optimisation routines that depend on a reasonable initial guess for the searched parameters. This, together with the fact that very different sets of parameters may yield indistinguishably good fits for a given experimental spectrum, gives rise to ambiguities in the data analysis in most but the simplest cases. In order to alleviate these difficulties, a computer program named PAScual was developed that incorporates two advanced algorithms to provide a robust fitting tool: on the one hand, it incorporates a global nonlinear optimisation routine based on the Simulated Annealing algorithm and, on the other hand, it yields information on the reliability of the results by means of a Markov Chain Monte-Carlo Bayesian Inference method. In this work the methods used in PAScual are described and tested against both simulated and experimental spectra, comparing the results with those from the well established program LTv9. The examples focus on the type of complex data that results from the study of self-assembled amphiphile materials containing co-existing aqueous and hydrocarbon regions

Building S.C.A.D.A. Systems in Scientific Installations with Sardana and Taurus

International audienceSardana and Taurus form a python software suite for Supervision, Control and Data Acquisition (SCADA) optimized for scientific installations. Sardana and Taurus are open source and deliver a substantial reduction in both time and cost associated to the design, development and support of control and data acquisition systems. The project was initially developed at ALBA and later evolved to an international collaboration driven by a community of users and developers from ALBA, DESY, MAXIV and Solaris as well as other institutes and private companies. The advantages of Sardana for its adoption by other institutes are: free and open source code, comprehensive workflow for enhancement proposals, a powerful environment for building and executing macros, optimized access to the hardware and a generic Graphical User Interface (Taurus) that can be customized for every application. Sardana and Taurus are currently based on the Tango Control System framework but also capable to inter-operate to some extend with other control systems like EPICS. The software suite scales from small laboratories to large scientific institutions, allowing users to use only some parts or employ it as a whole