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Rock 'n' Roll legend Little Richards dies of bone cancer

Little Richards died on Saturday at the age of 87




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'Ye bewakoof kisi aur ko banana': Mohammed Shami recalls instance when MS Dhoni told him off over a bouncer

The incident took place back in 2014 during India's test match against New Zealand.




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NSA Ajit Doval conducts high-level intelligence meet; asks to tighten counter-infiltration grid

According to a report by security agencies, the presence of around 450 terrorists, including those from Lashkar-e-Taiba (LeT), Hizbul Mujahideen (HM) and Jaish-e-Mohammad (JeM), has been seen on the launching pads adjacent to the Line of Control (LoC).




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Massive dust storm hits Delhi-NCR; accompanying rains bring relief from summer heat

The change in weather and the dust storm was witnessed in areas from Noida to Rajouri Garden in West Delhi.




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Ahmedabad: 29 held for Shahpur violence

Shahpur police, on the intervening night of Friday and Saturday, detained 29 persons in connection with the violence which erupted on Friday evening in the area.




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'The main challenge is social distancing in slums'

'When we talk about social distancing, it almost impossible to maintain this in slums.' 'So we had to talk to the people about cleanliness.' 'It was a task because everybody uses public toilets. So our volunteers targeted those spots to spread awareness.'




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SRK announces competition for budding filmmakers to make scary indoor movie




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Panchkula: Cook at police dept tests positive




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Random sampling finds two positive cases in two days in Panchkula




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Haryana: 25 people, including man with defected leg, on long march to UP’s Mirzapur




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Punjab and Haryana HC to hold 10 benches for hearing of urgent cases over video conferencing




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If the lockdown is not lifted, there may be defiance on a larger scale than at present




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This dry fruit is a healthy munching snack




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Indian women’s archery team to get final chance at Olympic quota in June next year




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Crossing final hurdle in World Cups down to experience and preparation: Anjum Chopra




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A versatile nanoreactor for complementary in situ X-ray and electron microscopy studies in catalysis and materials science

Two in situ `nanoreactors' for high-resolution imaging of catalysts have been designed and applied at the hard X-ray nanoprobe endstation at beamline P06 of the PETRA III synchrotron radiation source. The reactors house samples supported on commercial MEMS chips, and were applied for complementary hard X-ray ptychography (23 nm spatial resolution) and transmission electron microscopy, with additional X-ray fluorescence measurements. The reactors allow pressures of 100 kPa and temperatures of up to 1573 K, offering a wide range of conditions relevant for catalysis. Ptychographic tomography was demonstrated at limited tilting angles of at least ±35° within the reactors and ±65° on the naked sample holders. Two case studies were selected to demonstrate the functionality of the reactors: (i) annealing of hierarchical nanoporous gold up to 923 K under inert He environment and (ii) acquisition of a ptychographic projection series at ±35° of a hierarchically structured macroporous zeolite sample under ambient conditions. The reactors are shown to be a flexible and modular platform for in situ studies in catalysis and materials science which may be adapted for a range of sample and experiment types, opening new characterization pathways in correlative multimodal in situ analysis of functional materials at work. The cells will presently be made available for all interested users of beamline P06 at PETRA III.




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Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction

Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time.




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BioStruct-Africa: empowering Africa-based scientists through structural biology knowledge transfer and mentoring – recent advances and future perspectives

Being able to visualize biology at the molecular level is essential for our understanding of the world. A structural biology approach reveals the molecular basis of disease processes and can guide the design of new drugs as well as aid in the optimization of existing medicines. However, due to the lack of a synchrotron light source, adequate infrastructure, skilled persons and incentives for scientists in addition to limited financial support, the majority of countries across the African continent do not conduct structural biology research. Nevertheless, with technological advances such as robotic protein crystallization and remote data collection capabilities offered by many synchrotron light sources, X-ray crystallography is now potentially accessible to Africa-based scientists. This leap in technology led to the establishment in 2017 of BioStruct-Africa, a non-profit organization (Swedish corporate ID: 802509-6689) whose core aim is capacity building for African students and researchers in the field of structural biology with a focus on prevalent diseases in the African continent. The team is mainly composed of, but not limited to, a group of structural biologists from the African diaspora. The members of BioStruct-Africa have taken up the mantle to serve as a catalyst in order to facilitate the information and technology transfer to those with the greatest desire and need within Africa. BioStruct-Africa achieves this by organizing workshops onsite at our partner universities and institutions based in Africa, followed by post-hoc online mentoring of participants to ensure sustainable capacity building. The workshops provide a theoretical background on protein crystallography, hands-on practical experience in protein crystallization, crystal harvesting and cryo-cooling, live remote data collection on a synchrotron beamline, but most importantly the links to drive further collaboration through research. Capacity building for Africa-based researchers in structural biology is crucial to win the fight against the neglected tropical diseases, e.g. ascariasis, hookworm, trichuriasis, lymphatic filariasis, active trachoma, loiasis, yellow fever, leprosy, rabies, sleeping sickness, onchocerciasis, schistosomiasis, etc., that constitute significant health, social and economic burdens to the continent. BioStruct-Africa aims to build local and national expertise that will have direct benefits for healthcare within the continent.




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Generating three-color pulses in high-gain harmonic-generation free-electron lasers with a tilted electron bunch

A multi-color light source is a significant tool for nonlinear optics experiments, pump–dump/repump–probe experiments and in other fields. Here, a novel method is proposed to create three-color pulses based on a high-gain harmonic-generation (HGHG) free-electron laser with a tilted electron bunch. In this method, the initial bunch tilt is created by transverse wakefields after the bunch passes through a corrugated structure with an off-axis orbit, and is further enlarged in a following drift section. Then the tilted bunch experiences the off-axis field of a quadrupole magnet to cool down the large transverse velocity induced before. After that, it enters an HGHG configuration adopting a transverse gradient undulator (TGU) as the radiator, where only three separated fractions of the tilted bunch will resonate at three adjacent harmonics of the seed wavelength and are enabled to emit three-color pulses simultaneously. In addition, the use of the natural transverse gradient of a normal planar undulator instead of the TGU radiator to emit three-color pulses is also studied in detail. Numerical simulations including the generation of the tilted bunch and the free-electron laser radiation confirm the validity and feasibility of this scheme both for the TGU radiator and the natural gradient in the extreme-ultraviolet waveband.




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An enlightening procedure to explain the extreme power of synchrotron radiation

A simple approach exploits quantum properties to justify the dependence on γ4 of the total synchrotron emitted power. It also clarifies some apparent puzzles and brings to light the underlying, multiple relativistic phenomena.




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Performance of nearly fixed offset asymmetric channel-cut crystals for X-ray monochromators

X-ray double-crystal monochromators face a shift of the exit beam when the Bragg angle and thus the transmitted photon energy changes. This can be compensated for by moving one or both crystals accordingly. In the case of monolithic channel-cut crystals, which exhibit utmost stability, the shift of the monochromated beam is inevitable. Here we report performance tests of novel, asymmetrically cut, channel-cut crystals which reduce the beam movements by more than a factor of 20 relative to the symmetric case over the typical energy range of an EXAFS spectrum at the Cu K-edge. In addition, the presented formulas for the beam offset including the asymmetry angle directly indicate the importance of this value, which has been commonly neglected so far in the operation of double-crystal monochromators.




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Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording

An alternative approach to hard-X-ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high-energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k-resolution of 0.025 Å−1, equivalent to an angular resolution of 0.034°. A special objective lens with k-space acceptance up to 25 Å−1 allows for simultaneous full-field imaging of many Brillouin zones. Combined with time-of-flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s−1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core-level signals and one million for d-bands of transition metals. The concept of tomographic k-space mapping established using soft X-rays works equally well in the hard X-ray range. Sharp valence band k-patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF-resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X-ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) `amplifies' phase differences, making full-field hXPD a sensitive structural tool.




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Coherence properties of the high-energy fourth-generation X-ray synchrotron 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.




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Transmission measurement at the Bernina branch of the Aramis Beamline of SwissFEL

The transmission of the optical components of the Bernina branch of the Aramis beamline at SwissFEL has been measured with an X-ray gas monitor from DESY and compared with a PSI gas detector upstream of the optical components. The transmission efficiencies of the Mo, Si and SiC mirror coatings of the Aramis beamline and the various other in-beam components were evaluated and compared with theoretical calculations, showing an agreement of 6% or better in all cases. The experiment has also shown the efficacy of the high-harmonic rejection mirrors at the Bernina branch of the Aramis beamline at SwissFEL, and characterized the transmission efficiency of the on-line spectrometer in the Aramis beamline. The theoretical transmission of the mirror coatings match the experimental data to within 7%. The accuracy of these measurements was checked against a radiative bolometer from a Japanese collaboration and found to agree to a level of 4% or better. Further comparisons with a diamond detector from a US-based inter-institute collaboration demonstrated a good agreement for the attenuator settings of the beamline.




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X-ray fluorescence analysis of metal distributions in cryogenic biological samples using large-acceptance-angle SDD detection and continuous scanning at the Hard X-ray Micro/Nano-Probe beamline P06 at PETRA III

A new Rococo 2 X-ray fluorescence detector was implemented into the cryogenic sample environment at the Hard X-ray Micro/Nano-Probe beamline P06 at PETRA III, DESY, Hamburg, Germany. A four sensor-field cloverleaf design is optimized for the investigation of planar samples and operates in a backscattering geometry resulting in a large solid angle of up to 1.1 steradian. The detector, coupled with the Xspress 3 pulse processor, enables measurements at high count rates of up to 106 counts per second per sensor. The measured energy resolution of ∼129 eV (Mn Kα at 10000 counts s−1) is only minimally impaired at the highest count rates. The resulting high detection sensitivity allows for an accurate determination of trace element distributions such as in thin frozen hydrated biological specimens. First proof-of-principle measurements using continuous-movement 2D scans of frozen hydrated HeLa cells as a model system are reported to demonstrate the potential of the new detection system.




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Methods for dynamic synchrotron X-ray respiratory imaging in live animals

Small-animal physiology studies are typically complicated, but the level of complexity is greatly increased when performing live-animal X-ray imaging studies at synchrotron and compact light sources. This group has extensive experience in these types of studies at the SPring-8 and Australian synchrotrons, as well as the Munich Compact Light Source. These experimental settings produce unique challenges. Experiments are always performed in an isolated radiation enclosure not specifically designed for live-animal imaging. This requires equipment adapted to physiological monitoring and test-substance delivery, as well as shuttering to reduce the radiation dose. Experiment designs must also take into account the fixed location, size and orientation of the X-ray beam. This article describes the techniques developed to overcome the challenges involved in respiratory X-ray imaging of live animals at synchrotrons, now enabling increasingly sophisticated imaging protocols.




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A semi-analytical approach for the characterization of ordered 3D nanostructures using grazing-incidence X-ray fluorescence

Following the recent demonstration of grazing-incidence X-ray fluorescence (GIXRF)-based characterization of the 3D atomic distribution of different elements and dimensional parameters of periodic nanoscale structures, this work presents a new computational scheme for the simulation of the angular-dependent fluorescence intensities from such periodic 2D and 3D nanoscale structures. The computational scheme is based on the dynamical diffraction theory in many-beam approximation, which allows a semi-analytical solution to the Sherman equation to be derived in a linear-algebraic form. The computational scheme has been used to analyze recently published GIXRF data measured on 2D Si3N4 lamellar gratings, as well as on periodically structured 3D Cr nanopillars. Both the dimensional and structural parameters of these nanostructures have been reconstructed by fitting numerical simulations to the experimental GIXRF data. Obtained results show good agreement with nominal parameters used in the manufacturing of the structures, as well as with reconstructed parameters based on the previously published finite-element-method simulations, in the case of the Si3N4 grating.




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X-ray fluorescence detection for serial macromolecular crystallography using a JUNGFRAU pixel detector

Detection of heavy elements, such as metals, in macromolecular crystallography (MX) samples by X-ray fluorescence is a function traditionally covered at synchrotron MX beamlines by silicon drift detectors, which cannot be used at X-ray free-electron lasers because of the very short duration of the X-ray pulses. Here it is shown that the hybrid pixel charge-integrating detector JUNGFRAU can fulfill this function when operating in a low-flux regime. The feasibility of precise position determination of micrometre-sized metal marks is also demonstrated, to be used as fiducials for offline prelocation in serial crystallography experiments, based on the specific fluorescence signal measured with JUNGFRAU, both at the synchrotron and at SwissFEL. Finally, the measurement of elemental absorption edges at a synchrotron beamline using JUNGFRAU is also demonstrated.




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AP-XPS beamline, a platform for operando science at Pohang Accelerator Laboratory

Beamline 8A (BL 8A) is an undulator-based soft X-ray beamline at Pohang Accelerator Laboratory. This beamline is aimed at high-resolution ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), soft X-ray absorption spectroscopy (soft-XAS) and scanning photoemission microscopy (SPEM) experiments. BL 8A has two branches, 8A1 SPEM and 8A2 AP-XPS, that share a plane undulator, the first mirror (M1) and the monochromator. The photon beam is switched between the two branches by changing the refocusing mirrors after the monochromator. The acceptance angle of M1 is kept glancing at 1.2°, and Pt is coated onto the mirrors to achieve high reflectance, which ensures a wide photon energy range (100–2000 eV) with high resolution at a photon flux of ∼1013 photons s−1. In this article, the main properties and performance of the beamline are reported, together with selected experiments performed on the new beamline and experimental system.




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The HARE chip for efficient time-resolved serial synchrotron crystallography

Serial synchrotron crystallography (SSX) is an emerging technique for static and time-resolved protein structure determination. Using specifically patterned silicon chips for sample delivery, the `hit-and-return' (HARE) protocol allows for efficient time-resolved data collection. The specific pattern of the crystal wells in the HARE chip provides direct access to many discrete time points. HARE chips allow for optical excitation as well as on-chip mixing for reaction initiation, making a large number of protein systems amenable to time-resolved studies. Loading of protein microcrystals onto the HARE chip is streamlined by a novel vacuum loading platform that allows fine-tuning of suction strength while maintaining a humid environment to prevent crystal dehydration. To enable the widespread use of time-resolved serial synchrotron crystallography (TR-SSX), detailed technical descriptions of a set of accessories that facilitate TR-SSX workflows are provided.




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Understanding the mechanical limitations of the performance of soft X-ray monochromators at MAX IV laboratory

MAX IV is a fourth-generation, or diffraction-limited, synchrotron light source with a number of state-of-the-art beamlines. The performance of a beamline is, to a high degree, set by the energy resolution it can achieve, which in turn is governed to a large extent by the monochromator. During the design phase of a monochromator, the mechanical requirements must be fully understood and met with margin. During commissioning, the performance must be verified and optimized. In this paper, six soft X-ray monochromators at MAX IV beamlines (Bloch, Veritas, HIPPIE, SPECIES, FinEstBeAMS and SoftiMAX) are examined with a focus on their resolving power, energy range and the time required to change measurement range, as those parameters are dependent on each other. The monochromators have a modern commercial design, planned and developed in close collaboration with the vendors. This paper aims to present the current status of the commissioning at MAX IV with emphasis on elucidating the mechanical limitations on the performance of the monochromators. It contains analysis of the outcome and our approach to achieve fast and high-resolution monochromators.




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Time dependence of X-ray polarizability of a crystal induced by an intense femtosecond X-ray pulse

The time evolution of the electron density and the resulting time dependence of the X-ray polarizability of a crystal irradiated by highly intense XFEL femtosecond pulses is investigated theoretically. Rate equations for bound electrons and the Boltzmann equation for the unbound electron gas are used in calculations.




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Reconciling the regulatory role of Munc18 proteins in SNARE-complex assembly

Mammalian Munc18 proteins are essential for membrane fusion and human health. Here, we review the literature describing structural and in vitro data, and identify a possible explanation for the conflicting functional roles that have been reported.




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Nanocrystalline materials: recent advances in crystallographic characterization techniques

This feature article reviews the control and understanding of nanoparticle shape from their crystallography and growth. Particular emphasis is placed on systems relevant for plasmonics and catalysis.




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Investigating increasingly complex macromolecular systems with small-angle X-ray scattering

A review of recent and ongoing development and results within the field of biological solution small-angle X-ray scattering (BioSAXS), with a focus on the increasing complexity of biological samples, data collection and data evaluation strategies.




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Structure and function of dioxygenases in histone demethylation and DNA/RNA demethylation

The structure and function of dioxygenases in histone demethylation and DNA/RNA dimethylation are discussed.




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In-depth analysis of subclass-specific conformational preferences of IgG antibodies

An extended analysis of structural ensembles obtained from small-angle X-ray scattering data reveals subclass-specific conformational preferences of IgG antibodies, which are largely determined by the hinge-region structure.