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Dynamic three‐dimensional computed tomography (CT) imaging of liquid transport in porous media has primarily been conducted at high brilliance synchrotrons thus allowing fast, sometimes sub‐second, temporal resolution to be obtained. University laboratory CT instruments lack the photon flux available at synchrotrons, limiting the obtainable spatiotemporal resolution. Here, we discuss our experiences with instrumentation and software methods to conduct time‐resolved micro‐computed tomography (4D‐CT) experiments of flow in porous media, based on a conventional CT instrument operated with a highly undersampled number of projections. An experimental stage outfitted with syringe pumps placed on a slip ring allowed two‐phase flow experiments to be carried out with continuous unidirectional rotation and without obstruction of the liquid supply lines. An iterative reconstruction algorithm based on a priori information was used to provide high image quality and ∼30 s time resolution despite the few and low‐exposed projections compared to standard protocols. The experimental technique was demonstrated with imbibition and drainage in glass bead‐pack and Bentheimer sandstone samples with sub‐minute temporal resolution, allowing the liquid configurations just before and after fast dynamic phenomena such as cooperative pore‐filling events and Haines jumps to be captured. Power law scaling exponents for burst volumes associated with imbibition and drainage were estimated and compared with the literature. That 4D‐CT experiments can be carried out using conventional CT instruments to challenge contemporary permeability models is of high importance for many geo‐, bio‐ and environmental physics challenges. Plain Language Summary: Computed Tomography or CT is well‐known as a technique for investigating objects in 3D non‐destructively. In principle, 3D movies, referred to as "dynamic CT" or "4D CT" is a simple extension, requiring just a series of standard CT experiments to be carried out in sequence. In practice, however, there is a high demand for clever methods and algorithms that can simultaneously obtain high spatial and temporal resolutions. When more than one fluid is being transported through a porous medium, a plethora of phenomena take place, and 4D‐CT has proven a powerful tool to better understand the physics of porous media. Most 4D‐CT studies in the past have been carried out at synchrotron facilities, which are extremely high flux X‐ray sources, but also a scarce and expensive resource. We describe our experiences with 4D‐CT measurements of fluid transport in porous media, as performed in our home laboratory. Key Points: Time‐resolved 3D imaging of flow in porous mediaDynamic micro‐computed tomography [ABSTRACT FROM AUTHOR]

The formation of calcium carbonate (CaCO3) nanoparticles (NPs) in the presence of polystyrene sulfonate (PSS) as an additive was examined by time‐resolved small‐angle X‐ray scattering (SAXS) in a flow system that mimics experimental conditions used at home facilities where the precipitation can be achieved in a beaker. The experiments were carried out at low concentrations to remain in the dilute regime. A model‐independent analysis was performed using the Porod invariant which defines the scale factor, leaving only the distribution of radii as the adjustable parameter. The presence of the PSS additive strongly retards the precipitation of CaCO3 NPs. The formation of NPs reaches a state of equilibrium after a few minutes. Here, it is shown that the concentration of precursors at a fixed PSS concentration plays a key role in determining the size of the NPs obtained. A full analysis of the SAXS patterns was carried out using the Hurd–Flower model to account for the weaker intensity decay than the classical Porod behaviour. The temporal evolution of the particle radii was determined. Wide‐angle X‐ray scattering experiments carried out simultaneously show that the particles formed have the structure of vaterite with growth consistent with the evolution of the Porod invariant. [ABSTRACT FROM AUTHOR]

Utilising angular-varied illumination in Fourier Ptychography, the resolution of optical microscopes can be increased and the phase of the sample can also be recovered while maintaining a wide field-of-view. In this work, an Fourier Ptychography microscopy imaging setup is demonstrated using a 10X 0.28 NA objective lens and a dome-shaped light-emitting diode array illuminator. By increasing the refractive index of the medium between the sample and light sources using oil filled dome, a synthetic system numerical aperture of 0.68 is achieved using only 37 light-emitting diodes. The measured resolution of 345 nm at a wavelength of 530 nm closely matches the theoretical prediction. Furthermore, the results of the oil-medium illumination are compared to free-space illumination. The oil immersion on the illumination side effectively enhances the illumination numerical aperture as compared to air and reduces the need for far off-axis light-emitting diodes. The result is high-resolution Fourier Ptychography imaging with relatively fewer light-emitting diodes providing both short capture and reconstruction times. [ABSTRACT FROM AUTHOR]

Despite the abundance of shales in the Earth's crust and their industrial and environmental importance, their microscale physical properties are poorly understood, owing to the presence of many structurally related mineral phases and a porous network structure spanning several length scales. Here, the use of coherent X‐ray diffraction imaging (CXDI) to study the internal structure of microscopic shale fragments is demonstrated. Simultaneous wide‐angle X‐ray diffraction (WAXD) measurement facilitated the study of the mineralogy of the shale microparticles. It was possible to identify pyrite nanocrystals as inclusions in the quartz–clay matrix and the volume of closed unconnected pores was estimated. The combined CXDI–WAXD analysis enabled the establishment of a correlation between sample morphology and crystallite shape and size. The results highlight the potential of the combined CXDI–WAXD approach as an upcoming imaging modality for 3D nanoscale studies of shales and other geological formations via serial measurements of microscopic fragments. [ABSTRACT FROM AUTHOR]

This paper investigates the process of early urbanization in Oslo, Norway, during the initial period of early 11th–late 12th Century using a bioarchaeological approach. Through the use of isotope analyses performed on teeth and bone from 20 humans buried in Oslo during the first phases of urban settlement, individual dietary change and mobility are reconstructed. Oslo is traditionally perceived as one of many urban settlements initiated by royal power, and this paper contributes to this discussion by investigating the origin of the first settlers, and also how the early urban process affected their way of living. Results suggest that most individuals in the study were of local origin, and had a constant diet throughout life from childhood to its last phase. The absence of individual dietary change sharply contrasts the dynamic dietary patterns observed in people from the Viking age. Dietary variation between individuals does suggest, however, social differences among the early urban population of Oslo. [ABSTRACT FROM AUTHOR]

This letter discusses an alternative Fourier ptychography algorithm based on the scaled fast Fourier transform propagation. The advantage of this scheme is that it enables a zoom‐in capability of the object spectrum and complex pupil within the synthetic numerical aperture without increasing the overall matrix size. Thus, the high‐resolution complex object and complex pupil are recovered utilising a larger fraction of the elements in their respective representation matrices. Experimental results are presented showing the performance of this scheme against the tradition fast‐Fourier‐transform‐based approach. [ABSTRACT FROM AUTHOR]

A major limitation to the use of coherent X‐ray diffraction imaging (CXDI) for imaging soft materials like polymers and biological tissue is that the radiation can cause extensive damage to the sample under investigation. In this study, CXDI has been used to monitor radiation‐induced structural changes in metal‐coated poly(methyl methacrylate) microspheres. Using a coherent undulator X‐ray beam with 8.10 keV photon energy, 14 tomograms at a resolution of ∼30 nm were measured consecutively, which resulted in an accumulated dose of 30 GGy. The three‐dimensional images confirmed that the polymer core was strongly affected by the absorbed dose, giving pronounced mass loss. Specifically, as the metal–polymer composite was exposed to the X‐ray beam, a bubble‐like region of reduced density grew within the composite, almost filling the entire volume within the thin metallic shell in the last tomogram. The bubble seemed to have its initiation point at a hole in the metal coating, emphasizing that the free polymer surface plays an important role in the degradation process. The irradiation of an uncoated polystyrene microsphere gave further evidence for mass loss at the free surface as the radius decreased with increased dose. The CXDI study was complemented by X‐ray photon correlation spectroscopy, which proved efficient in establishing exposure dose limits. Our results demonstrate that radiation‐induced structural changes at the tens of nanometer scale in soft materials can be followed as a function of dose, which is important for the further development of soft‐matter technology. [ABSTRACT FROM AUTHOR]

Experimental nondestructive methods for probing the spatially varying arrangement and orientation of ultrastructures in hierarchical materials are in high demand. While conventional computed tomography (CT) is the method of choice for nondestructively imaging the interior of objects in three dimensions, it retrieves only scalar density fields. In addition to the traditional absorption contrast, other contrast mechanisms for image formation based on scattering and refraction are increasingly used in combination with CT methods, improving both the spatial resolution and the ability to distinguish materials of similar density. Being able to obtain vectorial information, like local growth directions and crystallite orientations, in addition to scalar density fields, is a longstanding scientific desire. In this work, it is demonstrated that, under certain conditions, the spatially varying preferred orientation of anisotropic particles embedded in a homogeneous matrix can be retrieved using CT with small-angle X-ray scattering as the contrast mechanism. Specifically, orientation maps of filler talc particles in injection-moulded isotactic polypropylene are obtained nondestructively under the key assumptions that the preferred orientation varies slowly in space and that the orientation of the flake-shaped talc particles is confined to a plane. It is expected that the method will find application in in situ studies of the mechanical deformation of composites and other materials with hierarchical structures over a range of length scales. [ABSTRACT FROM AUTHOR]

In solution-processable small molecule semiconductors, the extent of charge carrier wavefunction localization induced by dynamic disorder can be probed spectroscopically as a function of temperature using charge modulation spectroscopy (CMS). Here, it is shown based on combined field-effect transistor and CMS measurements as a function of temperature that in certain molecular semiconductors, such as solution-processible pentacene, charge carriers become trapped at low temperatures in environments in which the charges become highly localized on individual molecules, while in some other molecules the charge carrier wavefunction can retain a degree of delocalization similar to what is present at room temperature. The experimental approach sheds new insight into the nature of shallow charge traps in these materials and allows identifying molecular systems in which intrinsic transport properties could, in principle, be observed at low temperatures if other transport bottlenecks associated with grain boundaries or contacts could be removed. [ABSTRACT FROM AUTHOR]

Phase-contrast three-dimensional tomograms showing in unprecedented detail the mechanical response of a micro-composite subjected to a mechanical compression test are reported. The X-ray ptychography images reveal the deformation and fracture processes of a 10 μm diameter composite, consisting of a spherical polymer bead coated with a nominally 210 nm metal shell. The beginning delamination of the shell from the core can be directly observed at an engineering strain of a few percent. Pre-existing defects are shown to dictate the deformation behavior of both core and shell. The strain state of the increasingly compressed polymer core is assessed quantitatively through the local densification at sub-micron resolution, supported by finite element analysis. Nanoscale mechanics is of rapidly growing importance in materials science, biotechnology and medicine, and this study demonstrates the use of coherent X-ray microscopy as a powerful tool for in situ studies of the mechanical properties of nanostructured devices, structures, and composites. [ABSTRACT FROM AUTHOR]

ABSTRACT Injection molded polymer parts are known to exhibit structural gradients of crystallinity, crystallite phases and crystallite orientations. The structural variations depend on the geometry, the material properties, and the processing conditions, and affect the mechanical properties of the molded part. We explore the use of raster-scanning small- and wide-angle X-ray scattering (SAXS, WAXS) for mapping the microstructure in dogbone specimens of an isotactic polypropylene (PP) homopolymer and a talc-reinforced isotactic PP compound. The specimens were injection molded with different mold temperatures and injection speeds, and the mapping approach revealed systematic structural heterogeneities and asymmetries. Accompanying numerical simulations of the injection molding process yielded predictions of the flow pattern, including the shear rate distribution and the resulting orientation of the flake-shaped talc particles. We found a clear correspondence between the experimentally observed data and the simulations, in particular regarding the asymmetry of the orientation distributions relative to the center of the dogbone cross section, caused by asymmetric flow through the entrance of the mold. Furthermore, the shear rate distribution correlated with the occurrence of α- and β-phases. Subtle differences in the crystallized structures along the long axis of the dogbones suggest an explanation to the observation that the specimens studied always tended to break at the same position in tensile tests. The results clearly demonstrate the potential of mapping experiments which combine lateral resolution on macroscopic length scales with the molecular-scale resolution from scattering. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1157-1167 [ABSTRACT FROM AUTHOR]

Computationally efficient simulations of grazing-incidence X-ray diffraction (GIXD) are discussed, with particular attention given to textured thin polycrystalline films on supporting substrates. A computer program has been developed for simulating scattering from thin films exhibiting varying degrees of preferred orientation. One emphasized common case is that of a `fibre' symmetry axis perpendicular to the sample plane, resulting from crystallites having one well defined crystal facet towards the substrate, but no preferred in- plane orientation. Peak splitting caused by additional scattering from the totally substrate-reflected beam (two-beam approximation) and refraction effects are also included in the program, together with the geometrical intensity corrections associated with GIXD measurements. To achieve `user friendliness' for scientists less familiar with diffraction, the mathematically simplest possible descriptions are sought whenever feasible. The practical use of the program is demonstrated for a selected thin-film example, perylene, which is of relevance for organic electronics. [ABSTRACT FROM AUTHOR]

Differences in drug kinetics between supine rest and ambulation have been reported, but the relative contribution of postural changes and changes in the level of physical activity has not been evaluated. Ampicillin pharmacokinetics, glomerular filtration rate (GFR) and renal plasma flow (RPF) were studied in six male volunteers at rest in the sitting and lying position with an interval of 1 week. After intravenous administration ampicillin kinetics, analyzed according to a two-compartment open model, demonstrated significant changes in drug distribution when the position was changed from lying to sitting: alpha- increased by 50%, V1 and V beta increased by 19% and 22% respectively. Ampicillin clearance, the fraction of dose recovered from urine, GFR and RPF were, however, not influenced by the change in posture. Our data on effects of posture in resting subjects suggest that previously reported differences in drug elimination and RPF between lying and ambulatory subjects are largely due to differences in the level of physical activity. [ABSTRACT FROM AUTHOR]