The title pull–push chromophores, 2-[4-(di­methyl­amino)­benzyl­idene]-1H-indene-1,3(2H)-dione, C18H15NO2 (ID[1]) and (E)-2-{3-[4-(di­methyl­amino)­phen­yl]allyl­idene}-1H-indene-1,3(2H)-dione, C20H17NO2 (ID[2]), have donor–π-bridge–acceptor structures. The mol­ecule with the short π-bridge, ID[1], is almost planar while for the mol­ecule with a longer bridge, ID[2], is less planar. The benzene ring is inclined to the mean plane of the 2,3-di­hydro-1H-indene unit by 3.19 (4)° in ID[1] and 13.06 (8)° in ID[2]. The structures of three polymorphs of compound ID[1] have been reported: the α-polymorph [space group P21/c; Magomedova & Zvonkova (1978). Kristallografiya, 23, 281–288], the β-polymorph [space group P21/c; Magomedova & Zvonkova (1980). Kristallografiya, 25 1183–1187] and the γ-polymorph [space group Pna21; Magomedova, Neigauz, Zvonkova & Novakovskaya (1980). Kristallografiya, 25, 400–402]. The mol­ecular packing in ID[1] studied here is centrosymmetric (space group P21/c) and corresponds to the β-polymorph structure. The mol­ecular packing in ID[2] is non-centrosymmetric (space group P21), which suggests potential NLO properties for this crystalline material. In both compounds, there is short intra­molecular C—H⋯O contact present, enclosing an S(7) ring motif. In the crystal of ID[1], mol­ecules are linked by C—H⋯O hydrogen bonds and C—H⋯π inter­actions, forming layers parallel to the bc plane. In the crystal of ID[2], mol­ecules are liked by C—H⋯O hydrogen bonds to form 21 helices propagating along the b-axis direction. The mol­ecules in the helix are linked by offset π–π inter­actions with, for example, a centroid–centroid distance of 3.9664 (13) Å (= b axis) separating the indene rings, and an offset of 1.869 Å. Spectroscopic and electrochemical measurements show the ability of these compounds to easily transfer electrons through the π-conjugated chain.

Temperature is a ubiquitous environmental variable used to explore materials structure, properties and reactivity. This article reports a new paradigm for variable-temperature measurements that varies the temperature continuously across a sample such that temperature is measured as a function of sample position and not time. The gradient approach offers advantages over conventional variable-temperature studies, in which temperature is scanned during a series measurement, in that it improves the efficiency with which a series of temperatures can be probed and it allows the sample evolution at multiple temperatures to be measured in parallel to resolve kinetic and thermodynamic effects. Applied to treat samples at a continuum of temperatures prior to measurements at ambient temperature, the gradient approach enables parametric studies of recovered systems, eliminating temperature-dependent structural and chemical variations to simplify interpretation of the data. The implementation of spatially resolved variable-temperature measurements presented here is based on a gradient-heater design that uses a 3D-printed ceramic template to guide the variable pitch of the wire in a resistively heated wire-wound heater element. The configuration of the gradient heater was refined on the basis of thermal modelling. Applications of the gradient heater to quantify thermal-expansion behaviour, to map metastable polymorphs recovered to ambient temperature, and to monitor the time- and temperature-dependent phase evolution in a complex solid-state reaction are demonstrated.

Instrumentation for time-resolved small-angle neutron scattering measurements with sub-millisecond time resolution, based on Gähler's TISANE (time-involved small-angle neutron experiments) concept, is in operation at NIST's Center for Neutron Research. This implementation of the technique includes novel electronics for synchronizing the neutron pulses from high-speed counter-rotating choppers with a periodic stimulus applied to a sample. Instrumentation details are described along with measurements demonstrating the utility of the technique for elucidating the reorientation dynamics of anisometric magnetic particles.

A tandem-double-slit optical system was constructed to evaluate the practical beam emittance of undulator radiation. The optical system was a combination of an upstream slit (S1) and downstream slit (S2) aligned on the optical axis with an appropriate separation. The intensity distribution after the double slits, I(x1, x2), was measured by scanning S1 and S2 in the horizontal direction. Coordinates having 1/sqrt e intensity were extracted from I(x1, x2), whose contour provided the standard deviation ellipse in the x1–x2 space. I(x1, x2) was converted to the corresponding distribution in the phase space, I(x1, x1'). The horizontal beam emittance was evaluated to be 3.1 nm rad, which was larger than the value of 2.4 nm rad estimated by using ray-tracing. It was found that the increase was mainly due to an increase in beam divergence rather than size.

Strain tensor measurements are important for understanding elastic and plastic deformation, but full bulk strain tensor measurement techniques are still lacking, in particular for dynamic loading. Here, such a methodology is reported, combining imaging-based strain field mapping and simultaneous X-ray diffraction for four typical loading modes: one-dimensional strain/stress compression/tension. Strain field mapping resolves two in-plane principal strains, and X-ray diffraction analysis yields volumetric strain, and thus the out-of-plane principal strain. This methodology is validated against direct molecular dynamics simulations on nanocrystalline tantalum. This methodology can be implemented with simultaneous X-ray diffraction and digital image correlation in synchrotron radiation or free-electron laser experiments.

The unique diagnostic possibilities of X-ray diffraction, small X-ray scattering and phase-contrast imaging techniques applied with high-intensity coherent X-ray synchrotron and X-ray free-electron laser radiation can only be fully realized if a sufficient dynamic range and/or spatial resolution of the detector is available. In this work, it is demonstrated that the use of lithium fluoride (LiF) as a photoluminescence (PL) imaging detector allows measuring of an X-ray diffraction image with a dynamic range of ∼107 within the sub-micrometre spatial resolution. At the PETRA III facility, the diffraction pattern created behind a circular aperture with a diameter of 5 µm irradiated by a beam with a photon energy of 500 eV was recorded on a LiF crystal. In the diffraction pattern, the accumulated dose was varied from 1.7 × 105 J cm−3 in the central maximum to 2 × 10−2 J cm−3 in the 16th maximum of diffraction fringes. The period of the last fringe was measured with 0.8 µm width. The PL response of the LiF crystal being used as a detector on the irradiation dose of 500 eV photons was evaluated. For the particular model of laser-scanning confocal microscope Carl Zeiss LSM700, used for the readout of the PL signal, the calibration dependencies on the intensity of photopumping (excitation) radiation (λ = 488 nm) and the gain have been obtained.

A gas- and vapour-pressure control system synchronized with the continuous data acquisition of millisecond high-resolution powder diffraction measurements was developed to study structural change processes in gas storage and reaction materials such as metal organic framework compounds, zeolite and layered double hydroxide. The apparatus, which can be set up on beamline BL02B2 at SPring-8, mainly comprises a pressure control system of gases and vapour, a gas cell for a capillary sample, and six one-dimensional solid-state (MYTHEN) detectors. The pressure control system can be remotely controlled via developed software connected to a diffraction measurement system and can be operated in the closed gas and vapour line system. By using the temperature-control system on the sample, high-resolution powder diffraction data can be obtained under gas and vapour pressures ranging from 1 Pa to 130 kPa in temperatures ranging from 30 to 1473 K. This system enables one to perform automatic and high-throughput in situ X-ray powder diffraction experiments even at extremely low pressures. Furthermore, this developed system is useful for studying crystal structures during the adsorption/desorption processes, as acquired by millisecond and continuous powder diffraction measurements. The acquisition of diffraction data can be synchronized with the control of the pressure with a high frame rate of up to 100 Hz. In situ and time-resolved powder diffraction measurements are demonstrated for nanoporous Cu coordination polymer in various gas and vapour atmospheres.

Double-sided Fresnel zone plates are diffractive lenses used for high-resolution hard X-ray microscopy. The double-sided structures have significantly higher aspect ratios compared with single-sided components and hence enable more efficient imaging. The zone plates discussed in this paper are fabricated on each side of a thin support membrane, and the alignment of the zone plates with respect to each other is critical. Here, a simple and reliable way of quantifying misalignments by recording efficiency maps and measuring the absolute diffraction efficiency of the zone plates as a function of tilting angle in two directions is presented. The measurements are performed in a setup based on a tungsten-anode microfocus X-ray tube, providing an X-ray energy of 8.4 keV through differential measurements with a Cu and an Ni filter. This study investigates the sources of the misalignments and concludes that they can be avoided by decreasing the structure heights on both sides of the membrane and by pre-programming size differences between the front- and back-side zone plates.

This article describes a high-efficiency experimental configuration for a self-referenced lattice comparator with a `brush beam' of synchrotron radiation from a bending magnet and two linear position-sensitive photon-counting-type X-ray detectors. The efficiency is more than ten times greater compared with the `pencil-beam' configuration and a pair of zero-dimensional detectors. A solution for correcting the systematic deviation of d-spacing measurements caused by the horizontal non-uniformity of the brush beam is provided. Also, the use of photon-counting-type one-dimensional detectors not only improves the spatial resolution of the measurements remarkably but can also adjust the sample's attitude angles easily.

Errors in the article by Opara, Martiel, Arnold, Braun, Stahlberg, Makita, David & Padeste [J. Appl. Cryst. (2017), 50, 909–918] are corrected.

The residual strain distribution has been measured as a function of depth in both top coat and bond coat in as-received and heat-treated air plasma sprayed thermal barrier coating samples. High-energy synchrotron X-ray beams were used in transmission to produce full Debye–Scherrer rings whose non-circular aspect ratio gave the in-plane and out-of-plane strains far more efficiently than the sin2ψ method. The residual strain in the bond coat is found to be tensile and the strain in the β phase of the as-received sample was measured. The residual strains observed in the top coat were generally compressive (increasing towards the interface), with two kinds of nonlinear trend. These was a `jump' feature near the interface, and in some cases there was another `jump' feature near the surface. It is shown how these trend differences can be correlated to cracks in the coating.

A historical tool for crystallographic analysis is provided by the Hilton net, which can be used for manually surveying the crystal lattice as it is manifested by the Kikuchi bands in a gnomonic projection. For a quantitative analysis using the Hilton net, the projection centre as the relative position of the signal source with respect to the detector plane needs to be known. Interplanar angles are accessible with a precision and accuracy which is estimated to be ≤0.3°. Angles between any directions, e.g. zone axes, are directly readable. Finally, for the rare case of an unknown projection-centre position, its determination is demonstrated by adapting an old approach developed for photogrammetric applications. It requires the indexing of four zone axes [uvw]i in a backscattered Kikuchi diffraction pattern of a known phase collected under comparable geometric conditions.

In order to improve the instrumental accessibility of neutron diffraction techniques, many emerging compact neutron sources and in-house neutron diffractometers are being developed, even though the precision level of neutron diffraction experiments performed on such instruments was thought to be incomparable with that of large-scale neutron facilities. As a challenging project, the RIKEN accelerator-driven compact neutron source (RANS) was employed here to establish the technical environment for texture measurements, and the recalculated pole figures and orientation distribution functions of an interstitial-free steel sheet obtained from RANS were compared with the results from another two neutron diffractometers well established for texture measurement. These quantitative comparisons revealed that the precise neutron diffraction texture measurement at RANS has been realized successfully, and the fine region division of the neutron detector panel is invaluable for improving the stereographic resolution of texture measurements. Moreover, through selectively using the parts of the obtained neutron diffraction patterns that exhibit good statistics, the Rietveld texture analysis improves the reliability of the texture measurement to a certain extent. These technical research results may accelerate the development of other easily accessible techniques for evaluation of engineering materials using compact neutron sources, and also help to improve the data-collection efficiency for various time-resolved scattering experiments at large-scale neutron facilities.

An energy resolution of <10 µeV for the measurement of phonon energy change is achieved with the inelastic neutron spin echo technique on a conventional neutron triple-axis spectrometer.

The sin2ψ and cosα methods are compared via diffracting-grain identification from electron backscatter diffraction maps. Artificial textures created by the X-ray diffraction measurements are plotted and X-ray elastic constants of the diffracting-grain sets are computed.

This paper reports on the two-scale fractal structure of chromatin organization in the nucleus of the HeLa cell.

A new approach to variable-temperature measurements is presented, where the sample temperature changes continuously as a function of position.

Instrumentation for sub-millisecond time-resolved small-angle neutron scattering measurements at NIST is described and applied to the reorientation dynamics of elongated hematite nanoparticles.

The diffraction response of a single crystal to electric field measured by X-ray diffraction by angles close to π. Such schemes allow one to determine with high (~ 10–5–10–6) accuracy the relative changes in the lattice constant.

Birds do it. Bees do it. And in a laboratory in northern California, scientists using bumblebees recently figured out the best way to measure it--vertical lift!

The post Laboratory tests reveal precise way to measure vertical lift in bumblebees and other small insects and birds appeared first on Smithsonian Insider.

Now here is something to ruminate on. About 85 percent of the methane produced by a cow comes out of its mouth as burps. The […]

The post Monitoring methane? Now there is a better way to measure appeared first on Smithsonian Insider.

In many ways stars are like living beings. They’re born; they live; they die. And they even have a heartbeat. Using a novel technique, astronomers […]

The post DISCOVERY MEASURES “HEARTBEATS” OF A DISTANT GALAXY’S STARS appeared first on Smithsonian Insider.

Smithsonian scientists have joined NASA and other organizations this summer to do something incredible: launch a spacecraft, the Parker Solar Probe, into space and have […]

The post A solar probe is on its way to touch the sun. The Smithsonian built the tool that will measure the sun without melting appeared first on Smithsonian Insider.

While the Federal Motor Carrier Safety Administration’s (FMCSA) Safety Measurement System (SMS) used to identify commercial motor vehicle carriers at high risk for future crashes is conceptually sound, several features of its implementation need improvement, says a new congressionally mandated report from the National Academies of Sciences, Engineering, and Medicine.

The emergence of inexpensive small unmanned aircraft systems (sUASs) that operate without a human pilot, commonly known as drones, has led to adversarial groups threatening deployed U.S. forces, especially infantry units.

A new report from the National Academies of Sciences, Engineering, and Medicine recommends steps U.S. communities can take to better measure their progress in building resilience to disasters, including measuring resilience around multiple dimensions of a community, and incentivizing the measurement of resilience.

A centralized, consistently reported system of indicators of educational equity is needed to bring attention to disparities in the U.S. education system, says a new report by the National Academies of Sciences, Engineering, and Medicine.

When it comes to COVID-19 testing, questions remain about which of the tests available are reliable, how much testing is needed, and how to ensure access to testing. The latest COVID-19 Conversations webinar explored the challenges ahead.

A standardised method to help choose the most cost-effective measures to remediate contaminated sites has been developed by Austrian researchers. The method takes into account a wide range of factors, including the principles of sustainability.

Current knowledge on the availability of mineral resources is explored in a recent study, which focuses on phosphorus as a key example. Static measures of availability, such as the consumption-to-production ratio, are useful as early warning signals, the researchers suggest, but more dynamic indicators that consider technological development and population change are needed to better inform policy.

Assessing the potential of new environmental management tools often brings an ???innovation dilemma???: is it better to stick with what is known to work, or to implement new measures that are potentially more effective, but also more uncertain? Researchers have proposed an approach to deal with these dilemmas, and applied it to the case study of an invasive species programme in the US.

Two tagged Cuvier's beaked whales have shown intense and lasting avoidance behaviours in response to military sonar. In the first study of this kind, the whales showed significant responses to sonar at volumes that are currently assumed in the US to have no effect on behaviour.

Current knowledge on the availability of mineral resources is explored in a recent study, which focuses on phosphorus as a key example. Static measures of availability, such as the consumption-to-production ratio, are useful as early warning signals, the researchers suggest, but more dynamic indicators that consider technological development and population change are needed to better inform policy.

Individuals can assess how their behaviour is affecting nitrogen pollution with a newly developed nitrogen footprint calculator, which was developed by a team from the University of Virginia (U.S.) and the Energy Research Centre (ECN, the Netherlands). For many people in wealthy countries, reducing protein consumption to the recommended levels and reducing the amount of red meat and energy they consume would significantly lower their nitrogen footprint.

Comprehensive flood risk management should include household measures, such as improving a home’s stability and relocating heating systems to safe places within the house. According to new research, better communication with householders by authorities on the effectiveness of such measures, and how to implement them, could increase their uptake.

Despite the health benefits they bring, the trees and shrubs in our cities can cause health problems for pollen allergy sufferers. Now, a study by Spanish researchers has proposed guidelines for urban planting to reduce the effects of pollen on city-dwellers.

Scientists have measured how children and pregnant women are exposed to over 120 environmental factors influencing our health — from air and noise pollution to green space and access to public transport. The study gathered and analysed data from six European countries to build a picture of the ‘exposome’ — the array of environmental factors that humans are exposed to from the moment they are conceived. A better understanding of the exposome could help us understand the role of the environment in the onset of various diseases, including cancer and other chronic disorders such as cardiovascular disease.

Through a combination of human activities and climate change, the European environment is dehydrated. This thematic issue explores potential water management measures aimed at enhancing and safeguarding the water storage potential of Europe's ecosystems and aquifers.

New research in Spain has explored solutions to reducing traffic noise, and suggests that the best option is to combine global measures, such as speed restrictions, and local measures, such as noise screens.

The factors enabling eco-innovation have been analysed across 19 European countries in a new study. Regulations and environmental subsidies were found to be more important factors in Eastern Europe than in wealthier Western European countries. External research and development (R&D) was also more relevant in Eastern Europe, demonstrating the need for specific technology transfers from other countries and competitors.

The challenge of measuring the ‘absence of waste’ makes it particularly difficult to monitor and evaluate waste prevention policies. Researchers have examined the strengths and weaknesses of nine methods of assessing waste prevention, and recommend a hybrid approach, which combines the best of many methods, as particularly valuable.

Life-cycle indicators to monitor selected waste streams' impacts on the environment have been developed by the European Commission’s Joint Research Centre (JRC). These are presented in a recent study which describes a method for analysing waste's impacts using these indicators. The study also reveals the need for better statistics and more detailed categorisation of waste streams to effectively inform decision making in waste management.

Green roofs have been proposed to mitigate flooding in urban areas. This study combined field experiments and numerical simulations to investigate the ability of green roofs to absorb rainwater. The authors describe how green roofs can be most effective at mitigating flooding, providing findings which will be important for policy on green infrastructure.

Agri-environmental measures (AEM) are designed to encourage farmers to protect and enhance the environment on their farmland by paying them for the provision of environmental services. This study suggests that AEM would be more effective if payments were targeted to areas under the greatest environmental pressures, such as intensive agricultural regions — to gain maximum environmental benefits.