Compact X-ray sources based on inverse Compton scattering provide brilliant and partially coherent X-rays in a laboratory environment. The cross section for inverse Compton scattering is very small, requiring high-power laser systems as well as small laser and electron beam sizes at the interaction point to generate sufficient flux. Therefore, these systems are very sensitive to distortions which change the overlap between the two beams. In order to monitor X-ray source position, size and flux in parallel to experiments, the beam-position monitor proposed here comprises a small knife edge whose image is acquired with an X-ray camera specifically designed to intercept only a very small fraction of the X-ray beam. Based on the source position drift recorded with the monitor, a closed-loop feedback stabilizes the X-ray source position by adjusting the laser beam trajectory. A decrease of long-term source position drifts by more than one order of magnitude is demonstrated with this device. Consequently, such a closed-loop feedback system which enables stabilization of source position drifts and flux of inverse Compton sources in parallel to experiments has a significant impact on the performance of these sources.

An analysis of the coherence properties of the fourth-generation high-energy storage rings with emittance values of 10 pm rad is performed. It is presently expected that a storage ring with these low emittance values will reach diffraction limit at hard X-rays. Simulations of coherence properties were performed with the XRT software and an analytical approach for different photon energies from 500 eV to 50 keV. It was demonstrated that a minimum photon emittance (diffraction limit) reached at such storage rings is λ/2π. Using mode decomposition it is shown that, for the parameters of the storage ring considered in this work, the diffraction limit will be reached for soft X-ray energies of 500 eV. About ten modes will contribute to the radiation field at 12 keV photon energy and even more modes give a contribution at higher photon energies. Energy spread effects of the electron beam in a low-emittance storage ring were analysed in detail. Simulations were performed at different relative energy spread values from zero to 2 × 10−3. A decrease of the degree of coherence with an increase of the relative energy spread value was observed. This analysis shows that, to reach the diffraction limit for high photon energies, electron beam emittance should go down to 1 pm rad and below.

Leading scientists set out resource challenge of meeting net zero emissions in the UK by 2050  The Natural History Museum

Two earthquakes felt by residents in Lochaber  Press and Journal

Shift in Earth’s magnetic north throws navigators off course  Financial Times

Earthquake strikes the west Highlands  Press and Journal

'Several people' feel shaking as 4.2 magnitude earthquake strikes 190 miles from Dundee  The Courier

Geologists discover hundreds of buried valleys throughout Britain  Press and Journal

Residents speak of shock after being woken by EARTHQUAKE in early hours of morning  Hartlepool Mail

Four manganese(II) bromide coordination complexes have been prepared with four pyridine N-oxides, viz. pyridine N-oxide (PNO), 2-methyl­pyridine N-oxide (2MePNO), 3-methyl­pyridine N-oxide (3MePNO), and 4-methyl­pyridine N-oxide (4MePNO). The compounds are bis­(μ-pyridine N-oxide)bis­[aqua­dibromido­(pyridine N-oxide)manganese(II)], [Mn2Br4(C5H5NO)4(H2O)2] (I), bis­(μ-2-methyl­pyridine N-oxide)bis­[di­aqua­dibromido­manganese(II)]–2-methyl­pyridine N-oxide (1/2), [Mn2Br4(C6H7NO)2(H2O)4]·2C6H7NO (II), bis­(μ-3-methyl­pyridine N-oxide)bis­[aqua­dibromido­(3-methyl­pyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(H2O)2] (III), and bis­(μ-4-methyl­pyridine N-oxide)bis­[di­bromido­methanol(4-methyl­pyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(CH3OH)2] (IV). All the compounds have one unique MnII atom and form a dimeric complex that contains two MnII atoms related by a crystallographic inversion center. Pseudo-octa­hedral six-coordinate manganese(II) centers are found in all four compounds. All four compounds form dimers of Mn atoms bridged by the oxygen atom of the PNO ligand. Compounds I, II and III exhibit a bound water of solvation, whereas compound IV contains a bound methanol mol­ecule of solvation. Compounds I, III and IV exhibit the same arrangement of mol­ecules around each manganese atom, ligated by two bromide ions, oxygen atoms of two PNO ligands and one solvent mol­ecule, whereas in compound II each manganese atom is ligated by two bromide ions, one O atom of a PNO ligand and two water mol­ecules with a second PNO mol­ecule inter­acting with the complex via hydrogen bonding through the bound water mol­ecules. All of the compounds form extended hydrogen-bonding networks, and compounds I, II, and IV exhibit offset π-stacking between PNO ligands of neighboring dimers.

The title compounds, 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl benzoate, C20H19N3O4S (I), 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl isobutyrate 0.25-hydrate, C17H21N3O4S·0.25H2O (II), 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl propionate, C16H19N3O4S (III) and 4-(5-acetamido-3-acetyl-2-methyl-2,3-di­hydro-1,3,4-thia­diazol-2-yl)phenyl cinnamate chloro­form hemisolvate, C22H21N3O4S·0.5CHCl3 (IV), all crystallize with two independent mol­ecules (A and B) in the asymmetric unit in the triclinic Poverline{1} space group. Compound II crystallizes as a quaterhydrate, while compound IV crystallizes as a chloro­form hemisolvate. In compounds I, II, III (mol­ecules A and B) and IV (mol­ecule A) the five-membered thia­diazole ring adopts an envelope conformation, with the tetra­substituted C atom as the flap. In mol­ecule B of IV this ring is flat (r.m.s. deviation 0.044 Å). The central benzene ring is in general almost normal to the mean plane of the thia­diazole ring in each mol­ecule, with dihedral angles ranging from 75.8 (1) to 85.5 (2)°. In the crystals of all four compounds, the A and B mol­ecules are linked via strong N—H⋯O hydrogen bonds and generate centrosymmetric four-membered R44(28) ring motifs. There are C—H⋯O hydrogen bonds present in the crystals of all four compounds, and in I and II there are also C—H⋯π inter­actions present. The inter­molecular contacts in the crystals of all four compounds were analysed using Hirshfeld surface analysis and two-dimensional fingerprint plots.

p-Hydroxymandelate oxidase (Hmo) is a flavin mononucleotide (FMN)-dependent enzyme that oxidizes mandelate to benzoylformate. How the FMN-dependent oxidation is executed by Hmo remains unclear at the molecular level. A continuum of snapshots from crystal structures of Hmo and its mutants in complex with physiological/nonphysiological substrates, products and inhibitors provides a rationale for its substrate enantioselectivity/promiscuity, its active-site geometry/reactivity and its direct hydride-transfer mechanism. A single mutant, Y128F, that extends the two-electron oxidation reaction to a four-electron oxidative decarboxylation reaction was unexpectedly observed. Biochemical and structural approaches, including biochemistry, kinetics, stable isotope labeling and X-ray crystallo­graphy, were exploited to reach these conclusions and provide additional insights.

In this paper, the conformational polymorphism of a chlorinated diketo­pyrrolo­pyrrole (DPP) dye having flexible substituents in a non-hydrogen-bonding system is reported. The propyl-substituted DPP derivative (PR3C) has three polymorphic forms, each showing a different colour (red, orange and yellow). All polymorphs could be obtained concomitantly under various crystallization conditions. The results of the crystal structure analysis indicate that PR3C adopts different conformations in each polymorph. The packing effect caused by the difference in the arrangement of neighbouring molecules was found to play an important role in the occurrence of the observed polymorphism. The thermodynamic stability relationship between the three polymorphs was identified by thermal analysis and indicates that the yellow polymorph is the thermally stable form. The results indicate that the yellow form and orange form are enantiotropically related, and the other polymorph is monotropically related to the others.

Inelastic X-ray scattering is a powerful and versatile technique for studying lattice dynamics in materials of scientific and technological importance. In this article, the design and capabilities of the momentum-resolved high-energy-resolution inelastic X-ray spectrometer (HERIX) at beamline 30-ID of the Advanced Photon Source are reported. The instrument operates at 23.724 keV and has an energy resolution of 1.3–1.7 meV. It can accommodate momentum transfers of up to 72  nm−1, at a typical X-ray flux of 4.5 × 109 photons s−1 meV−1 at the sample. A suite of in situ sample environments are provided, including high pressure, static magnetic fields and uniaxial strains, all at high or cryogenic temperatures.

A Thomson scattering X-ray source can provide quasi-monochromatic, continuously energy-tunable, polarization-controllable and high-brightness X-rays, which makes it an excellent tool for X-ray fluorescence computed tomography (XFCT). In this paper, we examined the suppression of Compton scattering background in XFCT using the linearly polarized X-rays and the implementation feasibility of linearly polarized XFCT based on this type of light source, concerning the influence of phantom attenuation and the sampling strategy, its advantage over K-edge subtraction computed tomography (CT), the imaging time, and the potential pulse pile-up effect by Monte Carlo simulations. A fan beam and pinhole collimator geometry were adopted in the simulation and the phantom was a polymethyl methacrylate cylinder inside which were gadolinium (Gd)-loaded water solutions with Gd concentrations ranging from 0.2 to 4.0 wt%. Compared with the case of vertical polarization, Compton scattering was suppressed by about 1.6 times using horizontal polarization. An accurate image of the Gd-containing phantom was successfully reconstructed with both spatial and quantitative identification, and good linearity between the reconstructed value and the Gd concentration was verified. When the attenuation effect cannot be neglected, one full cycle (360°) sampling and the attenuation correction became necessary. Compared with the results of K-edge subtraction CT, the contrast-to-noise ratio values of XFCT were improved by 2.03 and 1.04 times at low Gd concentrations of 0.2 and 0.5 wt%, respectively. When the flux of a Thomson scattering light source reaches 1013 photons s−1, it is possible to finish the data acquisition of XFCT at the minute or second level without introducing pulse pile-up effects.

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.

The neutron powder diffractometer POWGEN at the Spallation Neutron Source has recently (2017–2018) undergone an upgrade which resulted in an increased detector complement along with a full overhaul of the structural design of the instrument. The current instrument has a solid angular coverage of 1.2 steradians and maintains the original third-generation concept, providing a single-histogram data set over a wide d-spacing range and high resolution to access large unit cells, detailed structural refinements and in situ/operando measurements.

An error in the article by Gao, Zhang, Zhu, Wu, Mo, Pan, Liu & Jiang [J. Appl. Cryst. (2019), 52, 637–642] is corrected.

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.

Described here are instructions for building and using an inexpensive automated microscope (AMi) that has been specifically designed for viewing and imaging the contents of multi-well plates. The X, Y, Z translation stage is controlled through dedicated software (AMiGUI) that is being made freely available. Movements are controlled by an Arduino-based board running grbl, and the graphical user interface and image acquisition are controlled via a Raspberry Pi microcomputer running Python. Images can be written to the Raspberry Pi or to a remote disk. Plates with multiple sample wells at each row/column position are supported, and a script file for automated z-stack depth-of-field enhancement is written along with the images. The graphical user interface and real-time imaging also make it easy to manually inspect and capture images of individual samples.

New measurements show that the Milky Way is bigger and more massive than previous data suggested, putting us on equal footing with our neighbor. Specifically, the Milky Way is 15 percent larger in size and contains 50 percent more mass. That is the cosmic equivalent of a 5-foot-5, 140-pound man suddenly bulking up to the size of a 6-foot-3, 210-pound NFL linebacker.

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Nearly 100 years ago, scientists detected the first signs of cosmic rays—subatomic particles (mostly protons) that zip through space at nearly the speed of light. […]

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Chi Cygni pulses once every 408 days. At its smallest diameter of 300 million miles, it becomes mottled with brilliant spots as massive plumes of hot plasma roil its surface. As it expands, Chi Cygni cools and dims, growing to a diameter of 480 million miles—large enough to engulf and cook our solar system out to the asteroid belt.

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This innovative facility will be at the front line of Earth defense by searching for "killer" asteroids and comets. It will map large portions of the sky nightly, making it an efficient sleuth for not just asteroids but also supernovae and other variable objects.

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NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way--a finding likened in terms of scale to the discovery of a new continent on Earth. The feature, which spans 50,000 light-years, may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

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"Physics for the 21st Century," a free, on-line course developed at the Harvard-Smithsonian Center for Astrophysics about current research in physics is now available.

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To honor Harvard-Smithsonian astronomer John Huchra, who passed away in October 2010, his friends and colleagues at the Harvard-Smithsonian Center for Astrophysics have created a […]

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The discovery of a pattern of X-ray “stripes” in the remains of an exploded star may provide the first direct evidence that a cosmic event […]

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If intelligent and more advanced civilizations exist on other planets then its a good bet that some of these civilizations turned to asteroid mining long ago. If so, the hallmarks of their mining activities, such as unusual dirty halos of cast-off dust and debris around large asteroids, might be detectable from earth.

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New research shows that some old stars might be held up by their rapid spins, and when they slow down, they explode as supernovae. Thousands of these "time bombs" could be scattered throughout our Galaxy.

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Depending on where the fish disperse from, the use of ‘stepping stones', flotsam or simply being an adult can help in the journey to find a new home.

The post Ability to raft with flotsam and use non-reef habitats helps tropical fish journey to new places, study finds appeared first on Smithsonian Insider.

For the first time, astronomers have detected around a burgeoning solar system a sprawling cloud of water vapor that’s cold enough to form comets, which could eventually deliver oceans to dry planets.

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Smithsonian astronomers have joined their colleagues from other observatories in a daring new venture: to photograph the giant black hole at the heart of our Milky Way galaxy.

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Two very different models explain the possible origin of Type Ia supernovae, and different studies support each model. New evidence shows that both models are correct - some of these supernovae are created one way and some the other.

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Last summer and this spring Boy Scout Arthur Carlton-Jones (shown here), working in conjunction with researchers at the Smithsonian Environmental Research Center in Edgewater, Md., […]

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A new study finds that since 1985, half of Australia's Great Barrier Reef coral has died.

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If you had a time machine that could take you anywhere in the past, what time would you choose? Most people would probably pick the […]

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Scientists have studied bird migration for centuries, but it remains one of nature’s great mysteries. How do birds find their way over long distances between […]

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Termites and ants are not something you’re likely to pour into a cereal bowl for breakfast or munch with toast and tea, but your ancient […]

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Einstein’s Theory of General Relativity predicts that accelerated masses emit gravitational waves, or ripples in space-time. Even though gravitational waves have yet to be detected […]

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One year ago, the olinguito (Bassaricyon neblina) stepped out of the forest shadows into the spotlight and onto the pages of science—the first carnivore species […]

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Wetlands Wetlands are one of the habitats to benefit most from conservation. The North American Wetlands Conservation Act has enabled strategic conservation projects covering a […]

The post The State of the Birds: Four critical habitats (videos) appeared first on Smithsonian Insider.