Noninvasive molecular and functional imaging in vivo is promising for detecting and monitoring various physiological conditions in animals and ultimately humans. To this end, we present a novel ...noninvasive technology, spectroscopic photoacoustic tomography (SPAT), which offers both strong optical absorption contrast and high ultrasonic spatial resolution. Optical contrast allows spectroscopic separation of signal contributions from multiple optical absorbers (e.g., oxyhemoglobin, deoxyhemoglobin, and a molecular contrast agent), thus enabling simultaneous molecular and functional imaging. SPAT successfully imaged with high resolution the distribution of a molecular contrast agent targeting integrin overexpressed in human U87 glioblastomas in nude mouse brains. Simultaneously, SPAT also imaged the hemoglobin oxygen saturation and the total hemoglobin concentration of the vasculature, which revealed hypoxia in tumor neovasculature. Therefore, SPAT can potentially lead to better understanding of the interrelationships between hemodynamics and specific biomarkers associated with tumor progression.
► Structural aspects and atomic intermixing processes in Be/W bilayers were studied. ► A strong intermixing at the Be/W interface takes place during the films deposition. ► A depth dependent ...oxidation gradient was observed for W species. ► The structure of the W top layer is specifically influenced by the Be layer.
Structural aspects and atomic intermixing processes in Be/W bilayers deposited on Si(001) substrates with Fe buffer layers enriched in the 57Fe Mössbauer isotope have been studied via atomic force microscopy, grazing incidence X-ray diffractometry, X-ray reflectometry, X-ray photoelectron spectroscopy and conversion electron Mössbauer spectroscopy. The mentioned investigations allowed a full sequential characterization of the involved interfaces. Various ionic configurations appeared for Fe or W, while an amorphous state was observed in the case of Be.
It has been proven that the Be layer has a negative influence on the roughness of the whole structure, which however presents an oxidation gradient from more oxidized elements at the surface towards more reduced elements in deeper layers. A strong diffusion of the W atoms inside the Be layer, induced by the deposition method, as well as of the Fe atoms inside the Be layer, induced by thermal annealing, has been evidenced.
•Be/W, Be/C layers deposited by TVA on Si substrate with thin sputtered Fe buffers.•Fe films were hydrogenated (300°C); Be/W and Be/C were annealed in vacuum (600°C).•Increase of oxidation near the ...surface; the hydrogenation reduces oxidation.•The annealing induces high interatomic diffusion all over the structure.•Mixed phases are formed by annealing: Fe–Be, Fe–C; no Fe–W phases are evidenced.
Atomic intermixing processes in relation to structural aspects and phase formation in Be based thin films subjected to different annealing treatments simulating the case of re-deposited layered structures on plasma facing components in nuclear fusion devices are reported. Accordingly, bilayers of Be/W and Be/C have been deposited on Si(001) substrates with Fe buffer layers. The Fe films have been prepared by radiofrequency sputtering and further processed by annealing in hydrogen atmosphere at 300°C, for 90min, at a pressure of 10 bars of H2. After the Be/W and Be/C bilayer deposition by means of thermionic vacuum arc method, annealing in vacuum at 600°C, for 10min has been applied to the complex structures. The influence of annealing on the phase composition and atomic intermixing processes in the complex structures has been studied by means of X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The layered structures present an oxidation gradient with oxide phases in the uppermost layers and non-oxidized phases in the lower layers, as observed from the XPS data. The CEMS results revealed that the as-deposited structures contain a main metallic Fe phase and secondary superparamagnetic Fe oxide phases at the Fe/Be interface, while annealed samples present a large contribution of Fe–Be and Fe–C mixtures. The annealing treatment induces considerable atomic interdiffusion, strongly dependent on the nature of the upper layer. In the case of Be/W system, the annealing provides a much rougher Be/W interface, while in case of the Be/C structure, the annealing treatment only homogenize the structure over the whole depth.
•A technology for GaSb surface cleaning is proposed.•The technology combines ion sputtering, chemical etching, annealing for oxide removal.•The ARXPS studies on GaSb surfaces are presented in a ...detailed manner.•The surface stoichiometry is restored after recommended technology for contacting.
Gallium antimonide (GaSb) is the basis of the most photovoltaic and thermophotovoltaic (TPV) systems and its innovative technological aspects based on modern ultra-high vacuum techniques are in trend for device achievement. The real surface of GaSb is modified by technological processes that can conduce to problems related to the reproducible control of its surface properties. The GaSb surface is reactive in atmosphere due to oxygen presence and exhibits a native oxide layer. The evolution of native oxides during the ion sputtering, chemical etching and thermal annealing processes for preparing the surface is presented in detailed way.
Ratios of surface constituents are obtained by Angle Resolved X-ray Photoelectron Spectroscopy (ARXPS). Moreover, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) and Low-Energy Electron Diffraction (LEED) are used for characterization. The surface stoichiometry is changed using a specific etchant (e.g. citric acid) at different etching time and is analyzed by ARXPS, SEM, EDS and AFM methods. The experimental results provide useful information regarding surface native oxides characteristics on n-GaSb(100) to be taken into account for development of low resistance contacts for TPV devices based on GaSb alloy.
There is increasing evidence in some malignancies that the tumor clone is heterogeneous in regard to proliferation and differentiation. The cancer stem cell hypothesis implies that not all the cells ...in the tumor have the same capacity to proliferate and maintain the growth of the tumor. Only a relatively small fraction of cells in the tumor, termed cancer stem cells (CSCs), possess the ability to proliferate and self-renew extensively. In the past decade, several groups have reported the existence of a CSC population in different human brain tumors from both children and adults. We report here the identification of a CSC population from a Boxer dog with glioblastoma multiforme (GBM) that possesses a great capacity for proliferation, self-renewal, and differentiation. This cloned cell line is aneuploid, forms neurospheres in culture, possesses CSC markers, and reproduces the original dog GBM when inoculated into the nude mouse brain.
Li–N–H and Li–Si–N–H composites have been synthesized by ball milling starting from lithium amide, lithium hydride and silicon powders. Hydrogen sorption behaviour was investigated for the ...Si-containing composites and a Li–N–H reference sample. The as-milled Si-containing sample showed the presence of the constituent powders but after few absorption–desorption cycles an important amount of Li
2SiN
2 appeared in both de-hydrogenated and re-hydrogenated composites. This phase was present in higher amount in the de-hydrogenated sample than in the re-hydrogenated one. The presence of this phase was also confirmed by XPS measurements. Li–N–H and Li–Si–N–H composites in de-hydrogenated state also contained lithium imide. X-ray diffraction data indicated a reversible hydrogen generating reaction between lithium amide, lithium hydride and silicon to produce Li
2SiN
2, lithium imide and hydrogen. The plateau pressure of Li–N–Si–H system is twice the one for Li–N–H at the same temperature (about 265
°C), as shown by pressure–composition isotherms in desorption mode. For the first time it has been observed a thermodynamic destabilization of Li–N–H by mixing it with Si.
•Engineering of Eurofer slab properties by hydrogenation treatments.•Hydrogenation modifies significantly the local atomic configurations at the surface.•Hydrogenation increases the expulsion of the ...Cr atoms toward the very surface.•Approaching binomial atomic distribution by hydrogenation in the next surface 100nm.
Reduced-activation steels such as Eurofer alloys are candidates for supporting plasma facing components in tokamak-like nuclear fusion reactors. In order to investigate the impact of hydrogen/deuterium insertion in their crystalline lattice, annealing treatments in hydrogen atmosphere have been applied on Eurofer slabs. The resulting samples have been analyzed with respect to local structure and atomic configuration both before and after successive annealing treatments, by X-ray diffractometry (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The corroborated data point out for a bcc type structure of the non-hydrogenated alloy, with an average alloy composition approaching Fe0.9Cr0.1 along a depth of about 100nm. EDS elemental maps do not indicate surface inhomogeneities in concentration whereas the Mössbauer spectra prove significant deviations from a homogeneous alloying. The hydrogenation increases the expulsion of the Cr atoms toward the surface layer and decreases their oxidation, with considerable influence on the surface properties of the steel. The hydrogenation treatment is therefore proposed as a potential alternative for a convenient engineering of the surface of different Fe-Cr based alloys.
Be/W and W/Be bilayers, of interest in regard to the specific behavior of plasma facing components (PFCs) were deposited on Si substrates by thermionic vacuum arc, with Fe, Fe-Cr and Fe-Cr-Al ...interlayers. The interlayers, with compositions approaching the one of the reduced activation steels used in supporting PFCs, were subsequently annealed in hydrogen atmosphere. The multilayers were characterized with respect to morphologic, structural, diffusional and atomic intermixing aspects via XRD, XRR, X-ray photoemission spectroscopy and Mössbauer spectroscopy. All as-prepared samples present partially amorphous structures. A main α-Fe phase is observed, as well as (superparamagnetic) secondary Fe oxides, metallic Fe with Si, Cr, W and Be neighbors, Be-rich Fe-Be and Fe-Si phases. High amounts of tungsten and tungsten oxides were also evidenced in the Fe layer. The strong atomic intermixing of W and Be layers was indirectly supported by the unusual densities of W and Be layers and 57Fe Mössbauer spectroscopy results.
•Be/W and W/Be bilayers were deposited on Si with hydrogenated Fe(Cr-Al) interlayers.•Metallic Fe, Fe and W oxides and other binary phases were found in the interlayers.•Specific atomic intermixing processes in Be/W and W/B structures were reported.
Surgical management of cerebellar infarction remains controversial. What surgical procedure should be performed when a patient presents neurological deterioration? When is the right moment to ...operate? Different treatments were proposed including decompressive suboccipital craniotomy, external ventricular drainage, or endoscopic third ventriculostomy.
We retrospectively reviewed five cases of cerebellar infarction treated with suboccipital craniotomy, excision of necrotic tissue, and duraplasty within a period of six months.
The five patients were evaluated with regard to presenting symptoms, Glasgow Coma Scale (GCS) before surgery, timing of surgery, computed tomographic scans and magnetic resonance imaging (MRI), neurological improvement, and outcome within a follow-up period of one year. Four patients made a good recovery, one patient died three days after surgery without neurological improvement.
These results suggest that decompressive suboccipital craniotomy may be an effective solution for good recovery if the patient is operated early, at the moment of the neurological deterioration.
Abstract Background and purpose Surgical management of cerebellar infarction remains controversial. What surgical procedure should be performed when a patient presents neurological deterioration? ...When is the right moment to operate? Different treatments were proposed including decompressive suboccipital craniotomy, external ventricular drainage, or endoscopic third ventriculostomy. Methods We retrospectively reviewed five cases of cerebellar infarction treated with suboccipital craniotomy, excision of necrotic tissue, and duraplasty within a period of six months. Results The five patients were evaluated with regard to presenting symptoms, Glasgow Coma Scale (GCS) before surgery, timing of surgery, computed tomographic scans and magnetic resonance imaging (MRI), neurological improvement, and outcome within a follow-up period of one year. Four patients made a good recovery, one patient died three days after surgery without neurological improvement. Conclusion These results suggest that decompressive suboccipital craniotomy may be an effective solution for good recovery if the patient is operated early, at the moment of the neurological deterioration.
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