To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Microcalorimeter X-ray detectors using a transition edge sensor depend for their linearity and energy scale on the stability of the operating point on the transition curve. We report on some sources of energy scale drift in microcalorimeter X-ray detectors and the manner in which they have been addressed. Previously observed drifts of >10 eV∕h have been reduced to 1–2 eV∕h. This improved stability has resulted in the observation of X-ray fluorescence linewidths of ⩽12 eV over 6 h of counting time.
In the emerging field of soft machines, large deformation of soft materials is harnessed to provide functions such as regulating flow in microfluidics, shaping light in adaptive optics, harvesting energy from ocean waves, and stretching electronics to interface with living tissues. Soft materials, however, do not provide all of the requisite functions; rather, soft machines are mostly hybrids of soft and hard materials. In addition to requiring stretchable electronics, soft machines often use soft materials that can deform in response to stimuli other than mechanical forces. Dielectric elastomers deform under a voltage. Hydrogels swell in response to changes in humidity, pH, temperature, and salt concentration. How does mechanics meet geometry, chemistry, and electrostatics to generate large deformation? How do molecular processes affect the functions of transducers? How efficiently can materials convert energy from one form to another? These questions are stimulating intriguing and useful advances in mechanics. This review highlights the mechanics that enables the creation of soft machines.
CheMin is a miniature X-ray diffraction/X-ray fluorescence instrument that is included in the payload of the Mars 2009 Mars Science Laboratory mission. A portable CheMin prototype was built to test the capability of the instrument for remote in situ mineralogical characterization of geological materials. The instrument was successfully deployed at a variety of Mars analog sites in Death Valley, CA, in May 2004.
The analysis of the distribution of pharmaceutical materials in tablet formulations, such as drugs and matrix elements, is critical to product performance and is used in such areas as quality control, impurity testing, and process monitoring. Recently imaging techniques, such as Raman, near-IR, and fluorescence imaging, have become popular for “visualization” of pharmaceutical formulations, allowing for spatial and chemical composition information to be obtained simultaneously. These methods have been primarily focused on molecular imaging, or spatial analysis of the molecular characteristics of the tablet formulation. However, elemental species are also an important part of pharmaceuticals. Micro X-ray fluorescence (MXRF) elemental imaging offers complementary information to molecular imaging techniques. In this study, MXRF was used for the elemental imaging of various commercial pharmaceutical drug and vitamin supplements. Specifically, elemental composition and heterogeneity were monitored for each different tablet.
In situ high-temperature X-ray diffraction (XRD) data have been collected for silver behenate, CH3(CH2)20COOAg. In the absence of development chemistry silver behenate exhibits four phase transformations when heated from room temperature to 200°C. Combining XRD and differential scanning calorimetry (DSC) results, the phase transformation temperatures and phase types have been determined. Types I, II, and III forms of silver behenate are found to be crystalline phases, whereas Types IV and V forms are liquid crystal phases.
A novel borate compound Ba3ScB9O18 has been synthesized by solid-state reaction and its structure has been determined and refined from powder X-ray diffraction data. This compound crystallizes in a hexagonal cell (space group P63/m) with lattice parameters a=7.1360(4) Å and c=16.5420(9) Å, and each unit cell contains two formulas. Its crystal structure is made up of planar B3O6 groups parallel to each other along the [001] direction, regular ScO6 octahedra, irregular BaO6 hexagons, and BaO9 polyhedra to form an analogue structure of Ba3YB9O18. DTA and TGA curves for Ba3ScB9O18 show that it is a chemically stable and congruent melting compound. Luminescence properties for Ba3ScB9O18 were investigated using fluorescence spectroscopy and X-ray excited luminescence measurements. Its emission spectrum upon UV excitation (330 nm) has exhibited a prominent blue-green emission band at about 490 nm, and its XEL spectra show an intense emission band in the range of 360 to 500 nm with peak center at 400 nm. The light yield of Ba3ScB9O18 powders is about 23% as large as that of BGO powders under the same measurement conditions. There seems to be a certain relationship between the scintillation properties and the structural features of Ba3ScB9O18.
Rietveld refinement using neutron, laboratory X-ray, and synchrotron powder diffraction data of NIST SRM clinker 8488 was performed. Quantitative phase analysis (QPA) results were compared between data, and with other studies. QPA results for the main phases in the clinker were found to be in agreement between the different data used here, and in and other studies, although the QPA of the tricalcium silicate polymorphs was shown to be inconsistent. The QPA results for the tricalcium aluminate phase varied between data types, and the neutron data were unable to distinguish this phase.
The technique of standard addition in combination with powder X-ray diffraction was used to identify and quantify the amount of Ln3+ segregating into secondary phases from Ln3+doped alkaline earth aluminates. Results indicate that Ln3+ ions are more soluble in CaAl2O4 than SrAl2O4 and BaAl2O4, with this being rationalized by the structural details of the A sites. These results indicate that the enhancement of the luminescence afterglow obtained by doping AAl2O4:Eu2+ samples with Ln3+ ions is a result of much lower doping levels than previously thought.
Low energy characteristic X-ray emission from Al2O3 monocrystalline specimens is measured under bombardment of 100 keV Xe+ ions. The electric field influence on emission of the X-rays of constitute elements in the specimens was investigated. The energy dispersive X-ray spectroscopy spectra show that the characteristic X-ray of Al-Kα seems to be depressed by the applied dc voltages, while the peak intensity of O-Kα was not notably influenced. The O-Kα peaks were broadened and the total counts increased as a higher dc bias was applied. It is possible that a dc electric field parallel to the target surface may influence the X-ray emission from it under ion bombardment.
Recent advances in stretchable electronics have seen the emergence of new technologies, and intensive efforts are being dedicated to embed some form of “intelligence” in various types of surfaces. However, the primary challenge in the field of stretchable electronics has been the development of stretchable or elastic electrical wiring that is both highly conductive and highly stretchable. Another challenge has been the development of manufacturing processes for integrating active device components as non-stretchable regions with electrical wiring as stretchable regions; the rigid/stretchable interfaces of these components require both high conductivity and high mechanical stability. In this article, we review the fabrication of carbon-nanotube-based elastic conductors with high electrical conductivity and mechanical stretchability as a representative example of stretchable organic integrated circuit electronics. Furthermore, we demonstrate the development of rubber-like stretchable integrated circuits for large-area human/machine interfaces. The fabrication process described in this article exploits the advantages of integrating a variety of electrical functional materials, ranging from rigid and semi-rigid elastomers to gels, with electronic circuits. The stretchable devices can be spread over a wide range of surfaces, including free surface curvatures and movable parts, thereby significantly increasing the scope of application of stretchable electrical and electronic circuits.
Characterization of materials used in the digital imaging industry has been performed using micro X-ray diffraction (microXRD) techniques. Case studies are described that demonstrate the use of microXRD for identification of phases, texture, and microstructure morphology of components used in imaging applications.
The structural models of three synthetic Al-substituted goethite specimens have been refined from the neutron data, including crystallographic determinations of the Al levels and H positions. The d-I data were calculated for the final models. A relationship between the c unit cell parameter and Al content has been extended to the entire goethite-diaspore solid-solution system, which makes the regression equation procedure simpler and more accurate. A second prospective H site could not be confirmed because of the quality of existing neutron data. However, it is hoped that a further neutron powder diffraction study of a synthetic, fully deuterated goethite material may allow the existence of the site to be demonstrated.
New layered bismuth oxides Bi2(BiCaNa)m−1NbmO3m+3(m=2-4) with the Aurivillius type phase were successfully synthesized. The structures of the compounds have been studied by X-ray powder diffraction and refined by the Rietveld method. Bi2.25Ca0.5Na0.25Nb2O9(m=2) has an orthorhombic crystal structure with lattice constants a=5.4478(1) Å;b=5.4770(2) Å;c=24.883(8) Å, space group A21am (No. 36). Bi2CaNaNb3O12 and Bi2.25Ca0.5Na1.25Nb3O12(m=3) are orthorhombic with Fmmm(No. 69) space group and the unit-cell parameters a=5.4473(7) Å, b=5.4770(3) Å, c=32.722(6) Å and a=5.4574(7) Å, b=5.4884 (3) Å, c=32.711(6) Å, respectively. The structure of Bi2CaNa2Nb4O15(m=4) was found to be orthorhombic with parameters a=5.4584(8) Å, b=5.4833(3) Å, c=40.534(1) Å and was refined in the space group A21am (No. 36).
The lattice parameters of α-alumina have been determined for temperatures in the range 20<T<1050 °C, using the lattice parameter of tungsten as a thermometer and a simple furnace in the diffractometer on the Australian beamline at the Photon Factory, Tsukuba, Japan. It is shown that the accuracy of this technique for measurement of cell parameters at temperatures up to ∼1200 °C is limited at present by uncertainty in the cell parameters of the reference material (i.e., tungsten) at high temperatures. Some problems with the equipment are discussed.
A new single-phase copper chromate compound was successfully synthesized by a hydrothermal method and characterized by XRD, SEM, TGA, and XRF analysis. The experimental XRD pattern was analyzed by automatic indexing and the compound was found to be monoclinic with space group P21/a and unit-cell parameters of a=10.1829(11) Å, b=4.9516(6) Å, c=7.2899(7) Å, and β=103.64(1)°. The chemical formula of the copper chromate compound determined by XRF and TGA was determined to be (NH4)1.5Cu2Cr2O8(OH)1.5⋅H2O. XRD results also showed that the synthesized compound decomposed into CuCr2O4 and CuO after being calcined at 600 °C.
Structural development of BPDA-PPD polyimide thin film has been investigated by in situ grazing incidence X-ray diffraction at the BL24XU beamline of the SPring-8. Optimizing the sample shape, two-dimensional images were measured successfully without sacrificing angle resolution. It has been clearly shown that the crystallization first begins in the in-plane direction, at the curing temperature of 180 °C, in which the periodic structure of the molecular chain axis (c axis) is developed. The crystallization in the surface normal (out-of-plane) direction is observed later, at the curing temperature above 300 °C. A slight increase of the d spacing of the c axis during heating process has been observed, suggesting the stretching of the contracted molecular chain in accordance with the curing process. In the cooling process, the decrease of the d spacings for a and b axes was considerable, which indicates thermal expansion of the crystals at high temperatures. The increases in the peak intensities during the cooling process have been observed, which indicate the d spacing of each axis becomes close to the equilibrium value to produce higher periodicity.
We have fabricated a bifocal miniature toroidal mirror that horizontally and vertically focuses to two different locations to provide a smaller footprint of the beam for grazing-incidence wide-angle scattering (GIWAXS), while at the same time focusing the beam in the horizontal direction on the detector to further enhance the angular resolution. At CHESS we traditionally use glass single-bounce monocapillary optics for a wide range of X-ray experiments to get a fine X-ray beam of 5 to 20 μm. This miniature toroidal mirror was prepared by designing and fabricating an X-ray focusing capillary in which the sagittal and meridional focusing is decoupled and only a quadrant of the accepted annulus is used for focusing the beam. The mirror produced a 120 μm horizontal by 25 μm vertical focus at 50 mm from the tip of the optic and a 44 μm horizontal by 70 μm vertical focus at 150 mm from the tip of the optic.