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The paper describes the seismic assessment of the San Felice sul Panaro Fortress (Italy), focusing the attention on the activation of the out-of-plane response of the North walkway, characterized by the presence of an apparatus of merlons which highlighted a significant damage after the Emilia earthquake (2012). Nonlinear kinematic analyses have been performed, referring to a macro-block model and considering both the original configuration and two different possible strengthened strategies. For the definition of the seismic input in terms of floor spectra, the analyses also benefitted from the results obtained for the global response through a detailed 3D model of the whole fortress. The results were coherent with the observed damage after the seismic event, highlighting in this way the reliability of the adopted modelling strategies and analysis method, and allowed to outline possible strengthening solutions targeted to minimize the impact on the monument and guarantee its preservation.

Gli eventi sismici registrati a partire dal 24 agosto 2016 hanno interessato quattro regioni dell’Italia centrale. Nella fase di emergenza particolare attenzione è stata posta alla valutazione danno-agibilità degli edifici scolastici al fine di consentire una rapida ripresa delle attività scolastiche. Il consorzio ReLUIS è stato fortemente coinvolto in tale attività gestendo, organizzando ed effettuando i sopralluoghi speditivi finalizzati a valutare il danno e l’agibilità di un considerevole numero di edifici scolastici sotto il coordinamento del Dipartimento della Protezione Civile. Tali sopralluoghi sono stati condotti da tecnici esperti in materia di rischio sismico di enti di ricerca, università italiane, Regioni, enti locali e nazionali. Lo strumento di rilievo del danno e dell’agibilità post-sismica adottato, la scheda di rilevamento di primo livello AeDES, ha consentito sia di esprimere un giudizio circa l’agibilità degli edifici scolastici sia di archiviare i dati afferenti alle caratteristiche tipologiche ed ai danni indotti dal terremoto alle componenti strutturali e non strutturali. Nel presente lavoro sono analizzati e discussi brevemente gli esiti delle ispezioni condotte su circa 280 complessi scolastici cui corrispondono all’incirca 500 corpi strutturalmente indipendenti. Successivamente la memoria focalizza l’attenzione sull’attività condotta da ReLUIS con riferimento alla valutazione della riparabilità di edifici scolastici dichiarati inagibili.

Gli eventi sismici registrati a partire dal 24 agosto 2016 hanno interessato quattro regioni dell'Italia centrale. Nella fase di emergenza particolare attenzione è stata posta alla valutazione danno-agibilità degli edifici scolastici al fine di consentire una rapida ripresa delle attività scolastiche. Il consorzio ReLUIS è stato fortemente coinvolto in tale attività gestendo, organizzando ed effettuando i sopralluoghi speditivi finalizzati a valutare il danno e l'agibilità di un considerevole numero di edifici scolastici sotto il coordinamento del Dipartimento della Protezione Civile. Tali sopralluoghi sono stati condotti da tecnici esperti in materia di rischio sismico di enti di ricerca, università italiane, Regioni, enti locali e nazionali. Lo strumento di rilievo del danno e dell'agibilità post-sismica adottato, la scheda di rilevamento di primo livello AeDES, ha consentito sia di esprimere un giudizio circa l'agibilità degli edifici scolastici sia di archiviare i dati afferenti alle caratteristiche tipologiche ed ai danni indotti dal terremoto alle componenti strutturali e non strutturali. Nel presente lavoro sono analizzati e discussi brevemente gli esiti delle ispezioni condotte su circa 280 complessi scolastici cui corrispondono all'incirca 500 corpi strutturalmente indipendenti. Successivamente la memoria focalizza l'attenzione sull'attività condotta da ReLUIS con riferimento alla valutazione della riparabilità di edifici scolastici dichiarati inagibili.

Stem cell based tissue engineering therapies involve the administration of ex vivo manipulated stem cell populations with the purpose of repairing and regenerating damaged or diseased tissue. Currently available methods of monitoring transplanted cells are quite limited. To monitor the outcomes of stem cell therapy longitudinally requires the development of non-destructive strategies that are capable of identifying the location, magnitude, and duration of cellular survival and fate. The recent development of imaging techniques offers great potential to address these critical issues by non-invasively tracking the fate of the transplanted cells. This review offers a focused presentation of some examples of the use of imaging techniques connected to the nanotechnological world in research areas related to stem cells. In particular investigations will be considered concerning tissue-engineered bone, treatment of intervertebral disc degeneration, treatment by human stem cells of muscular dystrophy of Duchenne in small animal models and the repair of spinal cord injuries.

X-ray planar waveguides are currently used tools, in synchrotron radiation facilities, to produce a coherent beam with typical dimensions in the range of tens or hundreds of nanometers. The properties of waveguided beams such as divergence and coherence turns out to be very interesting for several applications both in synchrotron and in laboratory sources. These features will be reviewed in the present paper for different coupling methods of the radiation field with the waveguide channel. Details of fabrication procedures and experimental results concerning front coupling waveguide are reported. The waveguide properties can be estimated from the far-field diffracted beam by a Fourier analysis giving the autocorrelation function of the exit field. Due to the high degree of coherence of the exiting beam, X-ray waveguides can be successfully exploited in coherent diffraction imaging experiments. We review results concerning Fresnel coherent diffraction imaging experiments with hard X-rays, using planar waveguides as optical elements in one and two dimensions.

The advent, in the near future, of compact X-ray sources like Thomson Back-Scattering (TBS) will allow the clinical application of advanced X-ray imaging techniques, such as phase contrast, with higher sensitivity and lower impact in terms of dose delivery. In this work, we theoretically investigated the possibility of using such sources for phase contrast imaging of micro-calcifications included in a breast tissue. In our study we analyzed the phase and amplitude distribution of the TBS source and we showed that this source can be used for phase contrast imaging since the source coherence at the sample position is sufficiently high for achieving good contrast and micrometer spatial resolution. Indeed the spatial coherence of a TBS source is closer to that of a synchrotron radiation source, and much better than that of a laboratory source. Moreover, we showed the advantages of phase imaging with respect to standard absorption imaging, in the specific case of micro-calcifications detection.

Elemental analysis of biological sample can give information about content and distribution of elements essential for human life or trace elements whose absence is the cause of abnormal biological function or development. However, biological systems contain an ensemble of cells with heterogeneous chemistry and elemental content; therefore, accurate characterization of samples with high cellular heterogeneity may only be achieved by analyzing single cells. Powerful methods in molecular biology are abundant, among them X-Ray microscopy based on synchrotron light source has gaining increasing attention thanks to its extremely sensitivity. However, reproducibility and repeatability of these measurements is one of the major obstacles in achieving a statistical significance in single cells population analysis. In this study, we compared the elemental content of human colon adenocarcinoma cells obtained by three distinct accesses to synchrotron radiation light.

The paper presents the analysis of the structural and constructive system together with that of the seismic response of the “Gothic house” in ArquataScrivia, that constitutes a rare example of timber framed masonry structure in Piedmont (Italy). Besides a certain diffusion around Europe, which is documented in the 19th century chronicles, in Italy there are only a few timber-framed buildings left. The timber frame system of the “Gothic house” presents some analogies with the French and German one (area in which it is more widespread than Italy) although it is characterized exclusively by the presence of horizontal and vertical timber elements. In the paper, the analysis of the building has been supported by an extensive investigation campaign that included the execution of several non-destructive tests on both masonry and timber elements. Preliminary step for setting-up the investigation plan was a sensitivity analysis carried out on an equivalent frame model of the building by performing nonlinear static analyses. Aims of such sensitivity analysis were, firstly, to address the as-built information phase and, then, to improve the reliability of the final model to be adopted for the seismic assessment.

The biological function of a chemical element in cells not only requires the determination of its intracellular quantity, but also the spatial distribution of its concentration. Different strategies can be employed to quantify and map the intracellular concentration of elements in single cells. The assessment of the intracellular elemental concentration, which is the relevant information, requires the measurement of cell volume. This challenging and demanding task requires combining different techniques allowing gathering of both morphological and compositional information on the same cell. Moreover, the need to analyse samples more similar to their natural state requires complex hardware equipment, and supplementary efforts in preparation protocols. Nevertheless, the response to the question: "where is it and how much?" is worth all these efforts. This review aims at providing an insight into the recent and most advanced techniques and strategies for quantifying and mapping chemical elements in single cells. We describe and discuss indirect detection techniques (label based) which make use of fluorescent dyes, and direct ones (label free), such as particle induced X-ray emission, proton backscattering spectrometry, scanning transmission ion spectrometry, nano-secondary ion mass spectrometry, X-ray fluorescence microscopy, complemented by X-ray imaging.

X-ray Waveguides (WG) are optical elements able to provide nanometer size coherent X-ray beams. Both Resonant beam Coupling (RBC) and Front Coupling (FC) can be implemented to couple the incident radiation with the WG. In this paper we implemented a computer code based on finite difference scheme solutions of parabolic wave equations to simulate the coupling and the propagation of electromagnetic waves into air-gap waveguides in Front Coupling mode. Both a synchrotron source and a table-top laboratory sources have been considered. In this last case the degree of coherence of the incoming beam has been explicitly taken into consideration. Air-gap WGs have been fabricated following simple procedures, and tested at the Elettra synchrotron source. The results are in good agreement with theoretical expectations.

A planar x-ray waveguide (WG) consisting of a diamond-like carbon layer sandwiched between two Ni layers is used to demonstrate for the first time the possibility of using WGs as optical elements with standard laboratory sources. The exit beam profile for the first two guided modes has been measured and analysed to demonstrate the high degree of beam coherence. The exit divergence and the beam size are reported and compared with theoretical predictions. Other relevant parameters, such as efficiency and gain, have been measured. This opens up interesting perspectives for the production of nanometre-sized x-ray beams with table-top laboratory sources.

The high spatial resolution X-ray microdiffraction by using X-ray optics can provide unique information on regions with very high gradients in physical quantities, as in the case of interfaces. Among the several available X-ray optics for synchrotron radiation producing high intensity micron and sub-micron beams, the X-ray waveguide (WG) can provide the smallest X-ray beam in one direction. Moreover, its applicability has been widened by an improved set-up installed at ID13 beamline at ESRF, where a new undulator is combined with an horizontally focusing mirror. In this work, we show different applications of waveguide-based microdiffraction, the first two regard biological problems and in particular the structural analysis of newly formed bone in ceramic scaffolds. The second application regards archeometry and in particular the sulphatation process and the thin gypsum crust formation on the surface of carbonate rocks (travertine, marbles), due to the exposure of the monuments at aggressive atmospheres. In the three cases, the local structural information derived thanks to the high spatial resolution demonstrates the power of the microdiffraction technique based on WG, and the possibility to apply this new methododogy in different scientific fields.

We present an innovative approach to couple elemental and morphological information from individual cells with high spatial resolution, and apply it to the problem of localization of magnesium and other light elements. The integration of Scanning fluorescence X-ray microscopy (SFXM), and Atomic Force Microscopy provided the relative concentration map of the elements in a single whole dehydrated cell. In this specific experiment spatial resolution of the order of 0.3 μm was obtained, but better resolution is in principle possible. The concentration map shows significant differences with respect to the distribution map, indicating higher Mg concentration in cell periphery.

The purpose of the present investigation is to demonstrate the power of the x-ray micro-diffraction technique in biological studies. In particular the reported experiment concerns the study of the interface between a Zr prosthetic device implanted in a rat femur and the newly-formed bone, with a spatial resolution of 0.5 microm. The obtained results give interesting information on the Zr deformation and on the crystallographic phase, the grain size and the orientation of the new bone. Moreover the study reveals a marked difference in the structure of the reconstructed bone with respect to the native bone, which cannot be appreciated with other techniques.

Examining existing experimental results for shallow rigid foundations subjected to vertical centric load (N), accompanied or not with a bending moment (M), two main non-linear mechanisms governing the cyclic response of the soil-foundation system can be distinguished: foundation uplift and soil yielding. A soil-foundation failure limit, is defined as a domain of resistance in the two dimensional (2D) load space (N, M) inside of which lie all the admissible combinations of loads; these latter correspond to a pure elastic, non-linear elastic or plastic behavior of the soil-foundation system, while the points lying on the failure limit correspond to a combination of loads leading to a failure of the soil-foundation system. In this study, the proposed resistance domain is constructed analytically based on mechanics. Original elastic limit, uplift initiation limit and iso-uplift limits are constructed inside this domain. These limits give a prediction of the mechanisms activated for each combination of loads applied to the foundation. A comparison of the proposed failure limit with experimental tests existing in the literature shows interesting results. Also, the developed uplift initiation limit and iso-uplift curves are confronted with others already proposed in the literature and widely used due to the absence of other alternatives, and remarkable differences are noted, showing evident errors in the past proposals and relevant accuracy for those given in the present work., {"references":["K. Terzaghi, \"Theoretical soil mechanics\", J. Willey, New York, 1943.","J.Brinch-Hansen, \"A revised and extended formula for bearing\ncapacity\", Danish geotechnical institute,Copenhagen, Bulletin No.28,\npp. 5-11, 1970.","R. Butterfield, J. Ticof, \"The use of physical models in design\n(discussion)\", Proceedings, 7th European Conference on Soil Mechanics\nand Foundation Engineering, Brighton, UK, Vol.4, pp. 259-261, 1979.","R. Butterfield, \"A simple analysis of load capacity of rigid footings on\ngranular media\", Journée de Géotechnique, pp. 128-134, 1980.","N. Gerolymos, G. Gazetas, \"Development of Winkler model for static\nand dynamic response of caisson foundations with soil and interface\nnonlinearities\", Soil Dynamics and Earthquake Engineering, Vol.26, pp.\n363-376, 2006a.","C. Crémer, A. Pecker, L. Davenne, \"Cyclic macroelement for soilstructure\ninteraction: material and geometrical nonlinearities\",\nInternational Journal for Numerical and Analytical Methods in\nGeomechanics, Vol.25, pp. 1257-1284, 2001.","R. Butterfield, G. Gottardi, \"A complete three-dimensional failure\nenvelope for shallow footings on sand\", Géotechnique, Vol.44, No.4, pp.\n181, 1994.","J. Ticof, \"Surface footings on sand under general planar loads\", PhD\nThesis, University of Southampton, UK, 1977.","L. Montrasio, R. Nova, \"Un modello di calcolo degli assestamenti di\nfondazioni superficiali sottoposte all'azione di carichi eccentrici ed\ninclinati\", Atti del convegno su \"Deformazioni dei terreni ed interazione\nterreno-struttura in condizioni di esercizio\", Monselice, Vol.2, pp. 141-\n152, 1998b.\n[10] G. Gottardi, \"Modellazione del comportamento di fondazioni\nsuperficiali su sabbia soggette a diverse condizioni di carico\", Ph.D.\nThesis, University of Padova, Italy, 1992.\n[11] R. Nova, L. Montrasio, \"Settlements of shallow foundations on sand:\nGeometric effects\", Geotechnique, Vol.47, No.1, pp. 49‐60, 1997.\n[12] G. Gottardi, G. T. Houlsby, \"Model tests of circular footings on sand\nsubjected to combined laods\", Department of Engineering Science,\nOxford University, Oxford, OUEL 2071/95, 1995.\n[13] R. Bovolenta, F. Schiaffino, R. Berardi, \"Sulla valutazione della stabilità\ndi fondazioni superficiali sottoposte a condizioni generali di carico\",\nFondazioni superficiali e profonde, 5th National conference of\ngeotechnical engineering researchers, Bari, 2006.\n[14] B.W. Byrne, G.T. Houlsby, \"Observations of footing behavior on loose\ncarbonate sands\", Géotechnique Vol. 51, No. 5, pp. 463-466, 2001.\n[15] L. Govoni, S. Gouvernec, G. Gottardi,, \"Centrifuge modelling of\ncircular shallow foundations on sand\", International Journal of Physical\nModelling in Geotechnics, Vol.10, No.2, pp. 35–46, 2010.\n[16] G. Gottardi, R. Butterfield, \"On the bearing capacity of surface footings\non sand under general planar load\", Soils and Foundations, Vol. 33,\nNo.3, pp. 68–79, 1993.\n[17] L. Zdravkovic, , P.M. Ng, D.M. Potts, \"Bearing capacity of surface\nfoundations on sand subjected to combined loading\", Numerical\nmethods in geotechnical engineering, Mestat ed.,Presses de\nl'ENPC/LCPC, Paris, pp. 323-330, 2002."]}

The effect of resonance, observed in X-ray waveguide layered structures in a characteristic way influences the scattering properties of the films. It is well known that in the resonant region the reflectivity shows a series of minima, usually very deep and extremely narrow. The positions and depths of the minima depend only on X-ray waveguide structural properties, on the X-ray wavelength and on the incident beam divergence. In the present work we propose and discuss the application of the X-ray waveguide and quasi X-ray waveguide film structures as tools to experimental evaluation of some quantities related to X-ray reflectometric or diffractometric measurements, like the beam divergence, wavelength, or angular distance. Examples of application of the X-ray waveguide as an excellent tool to estimate the effective beam divergence are shown. Properties of the X-ray waveguide elements as a handy wavelength or angular calibration standard are also mentioned.

We report on a metal–semiconductor–metal photodetector for the near infrared based on a thick relaxed Ge layer grown on a silicon substrate. The device exhibits a photoresponse spectrum extending down to 1.55 μm with maximum responsivity of 150 mA/W at the wavelength of 1.3 μm. An interdigited geometry allows a photoresponse speed of approximately 1.6 ns at low (1.5 V) bias voltage. Ge films were grown by solid source molecular beam epitaxy and characterised in situ with low energy electron diffraction and Auger spectroscopy. The crystalline quality was investigated by transmission electron microscopy and X-ray diffraction, while atomic force microscopy was used to assess surface morphology.

The USGS-PAGER Project is devoted to rapidly assess the consequences of severe earthquakes in the world. To improve the inventory and the vulnerability estimate, USGS made recourse to the EERI World Housing Encyclopedia (WHE) project, a web-based network of experts from around the world. A small group of experts, established by EERI, drafted a simple form to collect information at national level. For each country it was required to select the most significant construction types and to provide both the value of the collapse probability conditional upon seismic intensity and the fraction of population that lives and works in these construction types. Italy participated to the project and the Italian form was filled by the Seismic Risk Office-DPC. Several other research units accepted to participate to the project: RU-Genoa, RU-Naples, RU-Padua, RU-Pavia/Eucentre, RU-Potenza. The paper presents the contribution of the Italian Research Units to the PAGER project, providing an insight into the used methodologies and a comparison of the results.

We present here a novel X-ray diffraction imaging method which allows the determination of local structural properties with spatial resolution (in one dimension) of about 100 nm. The method is based on an X-ray microscope whose main element is a waveguide producing a divergent and coherent X-ray beam with vertical dimension below 100 nm. Applications for microelectronics materials and processes are presented.

This report discusses standing X-ray waves in thin films and their application for the determination of the position of a thin marker layer in a 100-nm-thick carbon layer. The position of 0.3–0.5-nm-thick titanium layers could be determined with an accuracy of 1% of the total film thickness. As the standing X-ray wave is a standing wave only in the direction parallel to the surface normal, it is travelling in the direction parallel to the surface. In the present study the properties of such a waveguided beam are studied when the beam exits from the waveguide end. Such a beam is of particular interest as it has dimensions of the order of 100–200 nm in one direction. Data will be presented for the shape of the beam, the energy tunability and the obtainable gain. The beam is found to be highly coherent and divergent. With the latter properties, an interesting application in microdiffraction experiments will be discussed in more detail. In a magnifying projection scheme the strain development in semiconductor crystalline material under oxidised lines of submicron width size could be studied with submicron lateral resolution and high sensitivity.

Auger and photoelectron time coincidence spectroscopy measurements on Si(100) have been carried out employing third generation synchrotron radiation source. This work has been focused on the particular treatment of the collected data required for this kind of experiment. The time structure characteristics of the European Synchrotron Radiation Facility light source have been taken into account in time coincidence data analysis, and compared with other sources. This study has shown the particular influence of the source in the distribution of accidental coincident events, revealing the need to introduce a suitable method for background subtraction in coincidence spectra.

This report discusses the latest performance data for X-ray waveguides applied in the production of hard X-ray micro-spots. It is possible to compress an X-ray radiation beam in a thin film waveguide in one direction down to the level of about 0.1 μm, a value which has not been achieved routinely with any other device. A gain factor of about 5 could be achieved in this case for a photon energy of 17 keV. The thin film waveguides were found to provide increasing transmission from 11 keV to 25 keV. As the exiting beam is not only of small size but also highly coherent and divergent it can be used in a number of microscopic techniques: e.g. micro-diffraction, micro-fluorescence, Gabor-holography, phase contrast microscopy.

The European project AXIS aims at fabricating an innovative X-ray source based on a field emitting CNT cathode. The basic components of such a source which determine the final properties have been presented here, i.e., the CNT cathode, the extractor AND THE ELECTRON OPTICS,. The results show that good control of the emission properties can be achieved, in agreement with electron trajectory simulations. These encouraging results form the basis for the realization of a source with improved brilliance, better stability, and pulsed operation.

Magnesium (Mg) plays crucial structural and regulatory roles within cells. Despite the extensive amount of data about the biochemistry of Mg, a complete picture of its regulation and cellular homeostasis is lacking. Thanks to recent improvements in third generation synchrotron X-ray sources, X-ray fluorescence microscopy (XRFM) is becoming a highly sensitive method for mapping elemental distributions in cells. XRFM maps the element content but not the concentration, which is a relevant variable in a biological context. We tackled this issue by combining XRFM with atomic force microscopy that was used to obtain morphological information of the sample. The aim of the present study was to compare the content and the distribution of Mg in drug-resistant and -sensitive tumor cell lines. Our data has shown a massive increase of Mg in LoVo drug-resistant cells. Moreover, the map of intracellular Mg showed marked differences in the pattern distribution between sensitive and resistant cells.

This chapter presents a theoretical analysis of electromagnetic field propagation in planar waveguides and experimental results obtained with synchrotron and laboratory sources. The basic equations of electromagnetic modes in a front-coupling planar WG are presented in section 2, and section 3 reports a comparison between computer simulation and experimental results in the general case of tapered waveguides. Then an original algorithm to retrieve the amplitude and phase of the electromagnetic field at the exit of the planar WG using an iterative method is presented (section 4). A theoretical analysis and computer simulation for WG with an additional periodic structure on the side reflecting walls of the WG are described in section 5, and experimental results are discussed in chapter 6 proving that spatial resolutions of few hundred nanometres in phase contrast imaging can be obtained with a laboratory source. Conclusions are drawn in section 7.

We report a method that allows a complete quantitative characterization of whole single cells, assessing the total amount of carbon, nitrogen, oxygen, sodium, and magnesium and providing submicrometer maps of element molar concentration, cell density, mass, and volume. This approach allows quantifying elements down to 10(6) atoms/mu m(3). This result was obtained by applying a multimodal fusion approach that combines synchrotron radiation microscopy techniques with off-line atomic force microscopy. The method proposed permits us to find the element concentration in addition to the mass fraction and provides a deeper and more complete knowledge of cell composition. We performed measurements on LoVo human colon cancer cells sensitive (LoVo-S) and resistant (LoVo-R) to doxorubicin. The comparison of LoVo-S and LoVo-R revealed different patterns in the maps of Mg concentration with higher values within the nucleus in LoVo-R and in the perinuclear region in LoVo-S cells. This feature was not so evident for the other elements, suggesting that Mg compartmentalization could be a significant trait of the drug-resistant cells.

Among the several available X-ray optics for synchrotron radiation producing micrometre and submicrometre beams with high intensity, the X-ray waveguide (WG) can provide the smallest hard X-ray beam in one direction. A drawback of this optics is that, owing to the divergence at the exit, a nanometre-sized spot on the sample can only be obtained if this is within a few micrometres of the WG exit. Another limitation is that in planar WGs the beam is compressed in only one direction. Here, using a dynamically bent elliptical Si/Pt mirror, the guided X-ray beam has been refocused at approximately 1 m from the waveguide exit. The large working distance between the device and the submicrometre focus leaves some space for sample environment (vacuum chamber, furnace, cryostat, magnets, high-pressure device etc.) and allows cross-coupled geometries with two WGs for efficient compression in two directions.

A technique for the determination of the total film thickness and the position of a marker layer in an amorphous graphite film by means of grazing incidence X-ray reflectometry and X-ray fluorescence is presented. This technique makes use of a strong resonance effect in the electric field intensity distribution measured in the graphite film. Angularly dependent fluorescence measurements on samples with different positions of a Ti marker showed that independent, non-destructive determination of the total graphite thickness and of the Ti position can be achieved with a relative accuracy of the order of 1%. The presented measurements were performed using a standard laboratory X-ray source and equipment.

In this paper we used the X-ray standing wave (XSW) technique to investigate the (Ge m Si n )p/Si(001) superlattice structure. This technique, being sensitive to both the modulus and phase of the structure factor, is a powerful tool to get structural information at atomic level. Unlike standard XSW where the standing wave field is generated in the substrate, here we studied both theoretically and experimentally the properties of the standing wave field generated in correspondence with the superlattice satellite peak close to the (004) reflection, whose periodicity is equal to the average lattice spacing of the superlattice. The information obtained on the superlattice structure from the combined use of diffraction and XSW will be discussed.

We have investigated electrical and structural characteristics of C coimplanted GexSi1−x layers formed by high dose Ge implantation in (100) Si followed by rapid thermal annealing at 1100 °C for 10 s. In the absence of C the layers, with Ge peak concentrations of about 15 at. %, are epitaxial and fully strained but show extrinsic dislocation loops in the Ge end of range region. In C coimplanted GexSi1−x the crystalline quality of the materials is improved since the formation of defects at the end of range is suppressed and the strain is reduced. From an electrical point of view the situation is reversed. The electrical characterization of p+/n diodes shows that, without C coimplantation, in GexSi1−x the hole mobility is larger than in Si, and the bandgap narrowing results in an increase of the minority carrier concentration. Moreover, the diffusion of minority carriers does not appear to be influenced by the presence of the secondary defects at the end of range. Vice versa, in C coimplanted GexSi1−x, even...

The glancing-angle reflectivity profiles in samples containing an X-ray waveguide layer are studied. Oscillations observed at angles within the region of resonance and above, are interpreted by angle dependent interference of the monochromatic X-ray beam in thin layer. The discussion is extended to the structures composed of more than one layer. Experimental reflectivity spectra recorded with Cu Kα radiation are compared with the theoretical calculations. It leads to the model of oscillations in reflectivity consistent both for the resonant and non-resonant regions, and clarifies interpretation of oscillations in the region above the resonances. A brief discussion of potential applications of the reflectivity spectra to the studies of structure of thin layers is done. PACS numbers: 68.65.+g, 78.20.Ci

This chapter deals with the fundamental properties of X-ray waveguides (WGs), whose development is a logical consequence of the theoretical and experimental work on X-ray standing waves. The different coupling modes and the formation of the wavefield inside the WG are reviewed. Some fabrication procedures and relevant applications are also briefly described.

Coherent X-ray diffraction imaging (CXDI) has been widely applied in the nanoscopic world, offering nanometric-scale imaging of noncrystallographic samples, and permitting the next-generation structural studies on living cells, single virus particles and biomolecules. The use of curved wavefronts in CXDI has caused a tidal wave in the already promising application of this emergent technique. The non-planarity of the wavefront allows to accelerate any iterative phase-retrieval process and to guarantee a reliable and unique solution. Nowadays, successful experiments have been performed with Fresnel zone plates and planar waveguides as optical elements. Here we describe the use of a single planar waveguide as well as two crossed waveguides in the experiments which first showed this optical element a promising tool for producing a line- or point-like coherent source, respectively.

We accurately measured the complex refractive index and dielectric functions from 0.2 to 5 eV of high-quality β-FeSi2 epitaxial films, with thicknesses ranging from 100 A to 8000 A, grown on Si(001) and Si(111) using two different techniques. Reflectance, transmittance and spectroscopic ellipsometry were used and the spectra were analyzed within a multilayer model, by checking the Kramers-Kronig consistency of the derived optical functions. These functions, compared with previous results for polycrystalline samples, showed a very good agreement with those obtained for bulk samples and a significant difference to films. The nature (direct or indirect) of the lowest optical gap and the effects of the film thickness and the substrate orientation on the optical response were also investigated.

The specific routes of biomineralization in nature are here explored using a tissue engineering approach in which bone is formed in porous ceramic constructs seeded with bone marrow stromal cells and implanted in vivo. Unlike previous studies this model system reproduces mammalian bone formation, here investigated at high temporal resolution. Different mineralization stages were monitored at different distances from the scaffold interface so that their spatial analysis corresponded to temporal monitoring of the bone growth and mineralization processes. The micrometer spatial resolution achieved by our diffraction technique ensured highly accurate reconstruction of the different temporal mineralization steps and provided some hints to the challenging issue of the mineral deposit first formed at the organic-mineral interface. Our results indicated that in the first stage of biomineralization organic tissue provides bioavailable calcium and phosphate ions, ensuring a constant reservoir of amorphous calcium phosphate (ACP) during hydroxyapatite (HA) nanocrystal formation. In this regard we suggest a new role of ACP in HA formation, with a continuous organic-mineral transition assisted by a dynamic pool of ACP. After HA nanocrystals formed, the scaffold and collagen act as templates for nanocrystal arrangement on the microscopic and nanometric scales, respectively. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.