In this paper we analyzed by electron microscopy and X-ray diffraction (XRD) the exposed lacustrine clay in a stratigraphic column at Charo Canyon, State of Michoacán, Mexico. Smectite, cris-tobalite, albite and quartz are the main mineral species in the sediments. Smectite is the most abundant and has a nanometric twinned small particle habit. The low crystallinity of the smectite detected in some of the samples seems to be associated with instability of the paleohydrological regime in which clayey material was deposited. Iron from underlying volcanic ash is apparently responsible for the iron concentration detected in the smectite structure.

Developments in X-ray analysis, and advances in scientific research, have dramatically influenced the types of data now considered suitable for inclusion in the Powder Diffraction FileTM (PDF®). Initially, the PDF was geared towards the identification of unknown crystalline materials by comparison of d-spacings and peak intensities. Today, the International Centre for Diffraction Data (ICDD) maintains and continuously enhances the quality and content of the PDF database to better provide customers and scientists with a comprehensive reference source that supports their needs, and interests. The events that initially led to the inclusion of crystalline polymer data to the PDF have recently been amended to also encompass semi-crystalline and amorphous polymeric materials as well. This paper discusses the resultant updates being made to the PDF in support of this new data form, and also highlights several features and benefits of providing this data to PDF users.

The classical implementation for putting quantitative figures on maps to reveal elemental compositions in transmission electron microscopy is by analytical methods like X-ray and energy-loss spectroscopy. Typically, the technique in use often depends on whether lighter or heavier elements are present and—more practically—which calibrations are available or sample-related properties are known. A framework linking electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray (EDX) signals such that absolute volumetric concentrations can be derived without assumptions made a priori about the unknown sample, is largely missing. In order to combine both techniques and harness their respective potentials for a light and heavy element analysis, we have set up a powerful hardware configuration and implemented an experimental approach, which reduces the need for estimates on many parameters needed for quantitative work such as densities, absolute thicknesses, theoretical ionization cross-sections, etc. Calibrations on specimens with known geometry allow the measurement of inelastic mean free paths. As a consequence, mass-thicknesses obtained from the EDX ζ-factor approach can be broken up and quantities like concentrations and partial energy-differential ionization cross-sections become accessible. ζ-factors can then be used for conversion into EELS cross-sections that are hard to determine otherwise, or conversely, connecting EDXS and EELS in a quantitative manner quite effectively.

Polycapillary optics are utilized in a wide variety of applications and are integral components in many state of the art instruments. Polycapillary optics operate by collecting X-rays and efficiently propagating them by total external reflection to form focused and parallel beams. We discuss the general parameters for designing these optics and provide specific examples on balancing the interrelations of beam flux, source size, focal spot-size, and beam divergence. The development of compact X-ray sources with characteristics tailored to match the requirements of polycapillary optics allows substantial reduction in size, weight, and power of complete X-ray systems. These compact systems have enabled the development of portable, remote, and in-line sensors for applications in industry, science and medicine. We present examples of the utility and potential of these optics for enhancing a wide variety of X-ray analyses.

Internal cracks caused by high temperature or excessive moisture during maize (Zea mays L.) kernel development were characterized, and their effects on kernel quality were assessed. Pre-harvest stress cracks are often located near the middle of the kernel along the embryo axis, but they were also detected in other positions, irrespective of the shape of the kernel. X-ray analysis enabled visualisation of stress cracks that are invisible to the human eye and, therefore, gave a better estimate of the percentage of cracks. However, low temperature scanning electron microscopy of the surface of milled kernels revealed small cracks not noticed by visual or X-ray inspection. All kernels tested in this way had a crack of some sort in the endosperm tissue. Cracks were also frequent in the scutellum, but rare in the embryo axis. Endosperm cracks followed the boundary of the starch granules, but did not extend into the pericarp tissue. In contrast to external cracks caused by mechanical impact, pre-harvest internal stress cracks generally are not detrimental to germination and vigour. However, if the crack is located inside or perpendicular to the embryo axis, it may affect the quality of the kernel, probably by impeding nutrient translocation to the embryo.