Pilatus is a silicon hybrid pixel detector system for detecting X-rays in single photon counting mode. The PILATUS II chip, fabricated in a radiation tolerant design with a standard 0.25 m CMOS process, was used to construct multichip modules with a size of 84 34 mm comprising 94'965 pixels. All calibrations and characterizations were carried out with monochromatic X-rays from a synchrotron source. In order to set any required threshold above the noise level between 2.14 keV and 22 keV the detector was calibrated with X-rays. An algorithm to adjust thresholds pixel-by-pixel and create trim files based on X-ray flat-field images was developed. The threshold dispersion was reduced from 343 eV to 36 eV by the means of trim files. An electronic noise of 447 eV has been measured. The PILATUS modules are suitable for various X-ray applications such as diffraction and imaging techniques.
SPIONs) which are clinically used as magnetic resonance imaging contrast agents. [4] In addition, application of an (alternating) external magnetic field for therapeutic purposes offers interesting perspectives in oncology, in that such nanoparticles can be used for a hyperthermia therapy or to target drug loaded particles to tumors. The latter is referred to as magnetic drug targeting. [5] In order to study the in vivo biodistribution of such particles, they have to be labeled by conjugation of fluorescent or radioactive agents. However, these chemical modifications can significantly change the interaction patterns with biological matter since they have a direct impact on particle size and polydispersity, electrokinetic potential (ζ-potential), and possibly the protein corona. [6][7][8][9] It is therefore recommended to carry out, whenever possible, physicochemical characterization, formulation development, pharmacokinetic studies, and hazard and safety evaluations with non-tagged nanoparticles. [10] In recent years, magnetic particle imaging (MPI), magnetic resonance imaging (MRI) or computed tomography [11] have been discussed as label-free alternative to trace engineered metal nanoparticles within a biological system. The latter technology takes advantage of their strong X-ray absorption. [12,13] In medical research, laboratory-based micro-computed tomography (μCT) has been used to monitor the biodistribution of metal-based nanoparticles in vitro or in small experimental animals. [13][14][15][16] A challenge Metal-based nanoparticles are clinically used for diagnostic and therapeutic applications. After parenteral administration, they will distribute throughout different organs. Quantification of their distribution within tissues in the 3D space, however, remains a challenge owing to the small particle diameter. In this study, synchrotron radiation-based hard X-ray tomography (SRμCT) in absorption and phase contrast modes is evaluated for the localization of superparamagnetic iron oxide nanoparticles (SPIONs) in soft tissues based on their electron density and X-ray attenuation. Biodistribution of SPIONs is studied using zebrafish embryos as a vertebrate screening model. This label-free approach gives rise to an isotropic, 3D, direct space visualization of the entire 2.5 mm-long animal with a spatial resolution of around 2 μm. High resolution image stacks are available on a dedicated internet page (http://zebrafish.pharma-te.ch). X-ray tomography is combined with physico-chemical characterization and cellular uptake studies to confirm the safety and effectiveness of protective SPION coatings. It is demonstrated that SRμCT provides unprecedented insights into the zebrafish embryo anatomy and tissue distribution of label-free metal oxide nanoparticles.
Many of the grand challenges in volcanic and magmatic research are focused on understanding the dynamics of highly heterogeneous systems and the critical conditions that enable magmas to move or eruptions to initiate. From the formation and development of magma reservoirs, through propagation and arrest of magma, to the conditions in the conduit, gas escape, eruption dynamics, and beyond into the environmental impacts of that eruption, we are trying to define how processes occur, their rates and timings, and their causes and consequences. However, we are usually unable to observe the processes directly. Here we give a short synopsis of the new capabilities and highlight the potential insights that in situ observation can provide. We present the XRheo and Pele furnace experimental apparatus and analytical toolkit for the in situ X-ray tomography-based quantification of magmatic microstructural evolution during rheological testing. We present the first 3D data showing the evolving textural heterogeneity within a shearing magma, highlighting the dynamic changes to microstructure that occur from the initiation of shear, and the variability of the microstructural response to that shear as deformation progresses. The particular shear experiments highlighted here focus on the effect of shear on bubble coalescence with a view to shedding light on both magma transport and fragmentation processes. The XRheo system is intended to help us understand the microstructural controls on the complex and non-Newtonian evolution of magma rheology, and is therefore
The actual displacement field in a glass during an in-situ Vickers indentation experiment was determined by means of X-ray tomography, thanks to the addition of 4 vol % of X-ray absorbing particles, which acted as a speckle to further proceed through digital volume correlation. This displacement was found to agree well with the occurrence of densification beneath the contact area. The intensity of the densification contribution (Blister field proposed by Yoffe) was characterized and provides evidence for the significant contribution of densification to the mechanical fields. Densification accounts for 27% of the volume of the imprint for the studied glass, that is expected to be less sensitive to densification than amorphous silica or window glass. A major consequence is that indentation cracking methods for the evaluation of the fracture toughness, when they are based on volume conservation, as in the case of Hill-Eshelby plastic inclusion theory, are not suitable to glass. The onset for the formation of the subsurface lateral crack was also detected. The corresponding stress is z 14 GPa and is in agreement with the intrinsic glass strength.
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