Wavefront sensing at X-ray free-electron lasers is important for quantitatively understanding the fundamental properties of the laser, for aligning X-ray instruments and for conducting scientific experimental analysis. A fractional Talbot wavefront sensor has been developed. This wavefront sensor enables measurements over a wide range of energies, as is common on X-ray instruments, with simplified mechanical requirements and is compatible with the high average power pulses expected in upcoming X-ray free-electron laser upgrades. Single-shot measurements were performed at 500 eV, 1000 eV and 1500 eV at the Linac Coherent Light Source. These measurements were applied to study both mirror alignment and the effects of undulator tapering schemes on source properties. The beamline focal plane position was tracked to an uncertainty of 0.12 mm, and the source location for various undulator tapering schemes to an uncertainty of 1 m, demonstrating excellent sensitivity. These findings pave the way to use the fractional Talbot wavefront sensor as a routine, robust and sensitive tool at X-ray free-electron lasers as well as other high-brightness X-ray sources.

Pressure can play a key role in probing the structure and dynamics of membrane assemblies, and is also critical to the biology and adaptation of deep-sea organisms. This article presents an overview of the effect of pressure on the structure of membranes and recent developments in high-pressure instrumentation.

Oil workers in North Sea feel effects of earthquake, with platform 'shaking'  Evening Telegraph

Characterizing and controlling the uniformity of nanoparticles is crucial for their application in science and technology because crystalline defects in the nanoparticles strongly affect their unique properties. Recently, ultra-short and ultra-bright X-ray pulses provided by X-ray free-electron lasers (XFELs) opened up the possibility of structure determination of nanometre-scale matter with Å spatial resolution. However, it is often difficult to reconstruct the 3D structural information from single-shot X-ray diffraction patterns owing to the random orientation of the particles. This report proposes an analysis approach for characterizing defects in nanoparticles using wide-angle X-ray scattering (WAXS) data from free-flying single nanoparticles. The analysis method is based on the concept of correlated X-ray scattering, in which correlations of scattered X-ray are used to recover detailed structural information. WAXS experiments of xenon nanoparticles, or clusters, were conducted at an XFEL facility in Japan by using the SPring-8 Ångstrom compact free-electron laser (SACLA). Bragg spots in the recorded single-shot X-ray diffraction patterns showed clear angular correlations, which offered significant structural information on the nanoparticles. The experimental angular correlations were reproduced by numerical simulation in which kinematical theory of diffraction was combined with geometric calculations. We also explain the diffuse scattering intensity as being due to the stacking faults in the xenon clusters.

It is shown that the 2p3d resonant inelastic X-ray scattering intensity is distorted by saturation and self-absorption effects, i.e. by incident-energy-dependent saturation and by emission-energy-dependent self-absorption.

The examination of anisotropic nanostructures, such as wires, platelets or spikes, inside a transmission electron microscope is normally performed only in plan view. However, intrinsic defects such as growth twin interfaces could occasionally be concealed from direct observation for geometric reasons, leading to superposition. This article presents the shadow-focused ion-beam technique to prepare multiple electron-beam-transparent cross-section specimens of ZnO nanospikes, via a procedure which could be readily extended to other anisotropic structures. In contrast with plan-view data of the same nanospikes, here the viewing direction allows the examination of defects without superposition. By this method, the coexistence of two twin configurations inside the wurtzite-type structure is observed, namely [2 {overline 1} {overline 1} 0]^{ m W}/(0 1 {overline 1} 1) and [2 {overline 1} {overline 1} 0]^{ m W}/(0 1 {overline 1} 3), which were not identified during the plan-view observations owing to superposition of the domains. The defect arrangement could be the result of coalescence twinning of crystalline nuclei formed on the partially molten Zn substrate during the flame-transport synthesis. Three-dimensional defect models of the twin interface structures have been derived and are correlated with the plan-view investigations by simulation.

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

Dynamical X-ray diffraction simulations of very asymmetric diffraction from single crystals of silicon were made to accompany an experimental rocking-curve topography study reported in a seperate paper. Effects on rocking curves were found and are reported. The development of Uragami [(1969), J. Phys. Soc. Jpn, 27, 147–154] for Takagi–Taupin simulations was followed and applied to the case of both convex and concave surface undulations.

Very asymmetric crystal diffraction was obtained from a finely polished silicon crystal set to reflect in Bragg diffraction at grazing incidence for the (333) reflection. The angle of incidence to achieve Bragg diffraction was varied between 1.08° and 0.33° by changing the X-ray energy from 8.100 to 8.200 keV. Topographic images obtained as the crystal was rocked were used to identify the effects of surface undulations, and the results are compared with dynamical X-ray diffraction calculations made with the Takagi–Taupin equations specialized to a surface having convex or concave features, as reported in an accompanying paper.

Neutron crystal structure analysis of hen egg-white lysozyme hydrogen/deuterium exchanged before crystallization were performed by the joint X-ray and neutron refinement. The differences in hydrogen/deuterium exchange behavior between this study and previous ones were observed.

The synthesis, characterization and study of structures from a series of bi­phenyls substituted at positions 3, 3', 4 and 4' with groups connected to the bi­phenyl core through oxygen atoms are presented here. The molecular conformation is extensively studied both in the solid as well as in the liquid state, and the effect of different actors (such as packing and chain length) on the torsion angle between aromatic rings is analyzed.

A putative open reading frame encoding GTP cyclohydrolase I from Listeria monocytogenes was expressed in a recombinant Escherichia coli strain. The recombinant protein was purified and was confirmed to convert GTP to dihydroneopterin triphosphate (Km = 53 µM; vmax = 180 nmol mg−1 min−1). The protein was crystallized from 1.3 M sodium citrate pH 7.3 and the crystal structure was solved at a resolution of 2.4 Å (Rfree = 0.226) by molecular replacement using human GTP cyclohydrolase I as a template. The protein is a D5-symmetric decamer with ten topologically equivalent active sites. Screening a small library of about 9000 compounds afforded several inhibitors with IC50 values in the low-micromolar range. Several inhibitors had significant selectivity with regard to human GTP cyclohydrolase I. Hence, GTP cyclohydrolase I may be a potential target for novel drugs directed at microbial infections, including listeriosis, a rare disease with high mortality.

A rare Longman’s beaked whale found stranded on the Hawaiian island of Maui in 2010 has scientists in Hawaii on the alert for a deadly disease known as morbillivirus which can lead to high mortality rates in dolphins and other marine mammals.

The post Rare whale beached in Hawaii infected with deadly marine-mammal virus appeared first on Smithsonian Insider.

Grow fast, die young is not a lifestyle normally associated with trees. But in the forests of the Northeastern United States the red maple follows […]

The post Effects of human impact are long lasting for forests in Northeast U.S. appeared first on Smithsonian Insider.

Through sheer coincidence, two Smithsonian researchers at the National Zoological Park have discovered that 18 percent of the white-tailed deer population in the Eastern United […]

The post Smithsonian study reveals white-tailed deer in eastern U.S. are infected with a malaria parasite appeared first on Smithsonian Insider.

This Secret Smithsonian Adventures series follows four middle schoolers as they foil events by two dastardly doers who try to dangerously change the true course […]

The post Secret Adventures: “Claws and Effect” appeared first on Smithsonian Insider.

Hem Sapkota, Jonathan D. Wren, and Gary J. Gorbsky

Centrosomes focus microtubules to promote mitotic spindle bipolarity, a critical requirement for balanced chromosome segregation. Comprehensive understanding of centrosome function and regulation requires a complete inventory of components. While many centrosome components have been identified, others may yet remain undiscovered. We have used a bioinformatics approach, based on "guilt by association" expression to identify novel mitotic components among the large group of predicted human proteins that have yet to be functionally characterized. Here we identify Chondrosarcoma-Associated Gene 1 (CSAG1) in maintaining centrosome integrity during mitosis. Depletion of CSAG1 disrupts centrosomes and leads to multipolar spindles more effectively in cells with compromised p53 function. Thus, CSAG1 may reflect a class of "mitotic addiction" genes whose expression is more essential in transformed cells.

Javad Fahanik-babaei, Bahareh Rezaee, Maryam Nazari, Nihad Torabi, Reza Saghiri, Remy Sauve, and Afsaneh Eliassi

We have determined the electropharmacological properties of a new potassium channel from brain mitochondrial membrane by planar lipid bilayer method. Our results showed the presence of a channel with a conductance of 150 pS at potentials between 0 and –60 mV in 200 cis/50 trans mM KCl solutions.

The channel was voltage-independent, with an open probability value ~0.6 at different voltages. ATP did not affect current amplitude and Po at positive and negative voltages. Notably, adding iberiotoxin, charybdotoxin, lidocaine, and margatoxin had no effect on the channel behavior. Similarly, no changes were observed by decreasing the cis-pH to 6. Interestingly, the channel was inhibited by adding sodium in a dose dependent manner. Our results also indicated a significant increase in mitochondrial complex IV activity and membrane potential and decrease in complex I activity and mitochondrial ROS production in the presence of sodium ions.

We propose that inhibition of mitochondrial K⁺ transport by Na ions on K⁺ channel opening may be important for cell protection and ATP synthesis.

This year’s El Niño event is one of the strongest on record and is still ramping up. Large parts of the tropics are turning into […]

The post Major El Nino Perfect opportunity for Global Change Research appeared first on Smithsonian Insider.

In the dark recesses of an underground fungus garden, a Panamanian leaf-cutting ant plucks a tuft of mycelia, the wispy part of the basidiomycete fungus […]

The post Mystery solved? Ants Protect Young From Infection By Cocooning Them in Fungus appeared first on Smithsonian Insider.

The analytical solution of the problem of X-ray spherical-wave Laue diffraction in a single crystal with a linear change of thickness on the exit surface is derived. General equations are applied to a specific case of plane-wave Laue diffraction in a thick crystal under the conditions of the Borrmann effect.

Elisa Reimer
Apr 23, 2020; 134:jcs246421-jcs246421
Articles

Apr 8, 2020; 133:e0702-e0702
RESEARCH HIGHLIGHT

Congestion charging in Stockholm has become more successful over time, according to a study by Swedish researchers. Although the total cost of a journey that enters the congestion charge zone has fallen in real terms since the charges were first introduced in 2006, there has consistently been around 29% less traffic within the zone, compared with levels in 2005.

Although there is evidence of harmful health and ecological effects associated with exposure to high doses of chemicals known as hormonally active agents – or endocrine disrupters – little is understood about the harm posed by exposure to the substances at low concentrations, such as those that typically exist in the environment, says a new report from a National Research Council committee.

Nearly 85 percent of the 29 million gallons of petroleum that enter North American ocean waters each year as a result of human activities comes from land-based runoff, polluted rivers, airplanes, and small boats and jet skis, while less than 8 percent comes from tanker or pipeline spills.

The environmental effects of oil and gas exploration and production on Alaska s North Slope have been accumulating for more than three decades, says a new report from the National Academies National Research Council.

Many U.S. farmers who grow genetically engineered (GE) crops are realizing substantial economic and environmental benefits -- such as lower production costs, fewer pest problems, reduced use of pesticides, and better yields -- compared with conventional crops, says a new report from the National Research Council.

Insufficient data on service members exposures to emissions from open-air burn pits for trash on military bases in Iraq and Afghanistan is one of the reasons why it is not possible to say whether these emissions could cause long-term health effects, says a new report from the Institute of Medicine.

Research to date on the effect of capital punishment on homicide rates is not useful in determining whether the death penalty increases, decreases, or has no effect on these rates, says a new report from the National Research Council.

Current federal tax provisions have minimal net effect on greenhouse gas emissions, according to a new report from the National Research Council.

Although more than $500 million in federally funded research on Persian Gulf War veterans between 1994 and 2014 has produced many findings, there has been little substantial progress in the overall understanding of the health effects, particularly Gulf War illness, resulting from military service in the war, says a new report from the Institute of Medicine (IOM) of the National Academies of Sciences, Engineering, and Medicine.

To improve and ensure the efficacy of restoration efforts in the Gulf of Mexico following Deepwater Horizon – the largest oil spill in U.S. history – a new report from the National Academies of Sciences, Engineering, and Medicine recommends a set of best practices for monitoring and evaluating ecological restoration activities.

Rising levels of noise in the ocean have been identified as a growing concern for the well-being of marine mammals, but other threats such as pollution, climate change, and prey depletion by fisheries may also harm marine mammals and influence their response to additional noise.

A new report from the National Academies of Sciences, Engineering, and Medicine highlights the complexity of communicating about science effectively, especially when dealing with contentious issues, and proposes a research agenda to help science communicators and researchers identify effective methods.

A new report from the National Academies of Sciences, Engineering, and Medicine offers a rigorous review of scientific research published since 1999 about what is known about the health impacts of cannabis and cannabis-derived products – such as marijuana and active chemical compounds known as cannabinoids – ranging from their therapeutic effects to their risks for causing certain cancers, diseases, mental health disorders, and injuries.

Mobilization of a rapid and robust clinical research program that explores whether investigational therapeutics and vaccines are safe and effective to combat the next infectious disease epidemic will depend on strengthening capacity in low-income countries for response and research, engaging people living in affected communities, and conducting safety trials before an epidemic hits, says a new report from the National Academies of Sciences, Engineering, and Medicine.

A new report by the National Academies of Sciences, Engineering, and Medicine proposes a strategy that the U.S. Environmental Protection Agency (EPA) should use to evaluate the evidence of adverse human health effects from low doses of exposure to chemicals that can disrupt the endocrine system.

A new congressionally mandated report from the National Academies of Sciences, Engineering, and Medicine takes a comprehensive look at evidence on the human health effects of e-cigarettes.

Introducing drone operations into the nation’s airspace can provide substantial benefits to society, such as preventing derailments, inspecting cell phone towers, delivering medical devices to patients in cardiac distress, and assisting firefighters, says a new congressionally mandated report by the National Academies of Sciences, Engineering, and Medicine.

A new report from the National Academies of Sciences, Engineering, and Medicine examines evidence on whether providing permanent supportive housing (PSH) – a combination of stable housing and supportive services -- to individuals who are experiencing homelessness improves their health.

Half-facepiece reusable elastomeric respirators are an effective and viable option for protecting health care workers from exposure to airborne transmissible contaminants or infectious agents — for example, influenza virus — during day-to-day work or with a sudden or rapid influx of patients, such as during a public health emergency, says a new report from the National Academies of Sciences, Engineering, and Medicine.

Medications to Treat Opioid Addiction Are Effective and Save Lives, But Barriers Prevent Broad Access and Use, Says New Report

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 new report from the National Academies of Sciences, Engineering, and Medicine examines the effects and efficacy of using dispersants in marine oil spill response.