cto Health Care Provider Boot Camp Day 2: How to Become a Texas Workers’ Compensation Treating Doctor By www.tdi.texas.gov Published On :: Thu, 06 Feb 2025 18:00:00 GMT Health Care Provider Boot Camp Day 2: How to Become a Texas Workers’ Compensation Treating Doctor Full Article
cto Designated Doctor 101 Workshop By www.tdi.texas.gov Published On :: Fri, 24 Jan 2025 14:00:00 GMT Designated Doctor 101 Workshop Full Article
cto Basic instructor course No. 1014 By www.tdi.texas.gov Published On :: Mon, 02 Dec 2024 14:00:00 GMT Basic instructor course No. 1014 Full Article
cto Designated Doctor Extent of Injury webinar By www.tdi.texas.gov Published On :: Fri, 15 Nov 2024 15:30:00 GMT Designated Doctor Extent of Injury webinar Full Article
cto Retail Sector - Cyber Threat Intelligence Report 2024 By www.retailtechnologyreview.com Published On :: NCC Group have just released a free CyberSecurity Threat Intelligence Report for the Retail sector as it enters its busiest spell, the "GoldenQuarter".It will help retailers manage an increasing surge in demand across their IT operations and supply chains. Full Article Critical Issues Surveillance and Security Internet Retailing Cyber Security
cto Dyslexia Awareness Week: Ensuring website inclusivity in the retail sector By www.retailtechnologyreview.com Published On :: Mon, 13 Nov 8180 17:28:37 +0000 As Dyslexia Awareness Week (07-13 October 2024) arrives this week, digital transformation specialists Sherwen Studios are advocating for retailers to reconsider how accessible their website is for users affected by dyslexia. Full Article Internet Retailing Retail Supply Chain Critical Issues
cto The convenience factor: Why social selling is crucial for the future of retail By www.retailtechnologyreview.com Published On :: By Georgia Leybourne, Chief Marketing Officer, Linnworks.Success in ecommerce and retail today hinges on consumer convenience. It is fast becoming a powerful tool in the e-commerce industry, transforming the way businesses engage with their customers and increasing sales through social commerce. Full Article Retail Supply Chain Internet Retailing Critical Issues
cto Dakota smashes 2023 revenue targets as growth trajectory continues By www.retailtechnologyreview.com Published On :: Mon, 13 Nov 4800 17:05:47 +0000 Following a record year in 2022, real-time data capture, printing, mobility and voice-directed solutions specialist, Dakota Integrated Solutions, has again exceeded projected revenue and growth targets during 2023. Full Article RFID Data Capture
cto Could self-checkouts become the norm across all retail sectors? By www.retailtechnologyreview.com Published On :: By Ed Smith, freelance journalistSelf-checkouts have proven to be an increasingly popular option for shoppers to take control of their own scanning of items. It can feel a little quicker and allows you to scan then pack your goods at your own pace rather than trying to keep up with a cashier. Full Article Critical Issues Kiosk Technology EPoS Systems
cto Manufacturing & Logistics IT - October 2024 edition By www.retailtechnologyreview.com Published On :: This issue features a Special Technology Report looking in depth at the latest developments in the world of Printing and Labelling solutions.Also included is a ‘Cover Story’: Gartner explains that by 2026, 30% of enterprises will automate more than half of their network activities, an increase from under 10% in mid-2023. Full Article Critical Issues Print and Label
cto Russia annihilates Sweden's SAAB AEW&C instructors in missile strike on Poltava By english.pravda.ru Published On :: Fri, 06 Sep 2024 16:56:00 +0300 The Ukrainian army is suffering huge losses in the Kursk direction of hostilities. Thousands of Ukrainian fighters have gone missing during the incursion into the Russian region. Many already criticise President Zelensky for going on such an "adventure." Ukrainian commanders order their soldiers to take part in "meat-grinding" assaults. Those who refuse are shot for treason. Captured Ukrainians share stories of real genocide in the ranks of the Armed Forces of Ukraine. Ukrainian leaders use common people in uniforms as "consumables", whereas the army of Ukraine has turned into a self-destruction machine under the dictation of the Kyiv authorities. Meanwhile, two Iskander missiles — some call them Korean KN-23 — annihilated another temporary deployment point of the Ukrainian Armed Forces in Sumy where units of the 54th, 61st, 45-1 and 81st brigades of the Ukrainian Armed Forces had arrived from the Kursk direction. Full Article Incidents
cto Sex after vaccination is good, Russian doctor says By english.pravda.ru Published On :: Fri, 09 Jul 2021 12:09:00 +0300 There is nothing wrong with having sex after vaccination against COVID-19, Vladislav Zhemchugov, Doctor of Medical Sciences, specialist in especially dangerous infections, said in an interview with RIA Novosti. According to him, sex is an energy-intensive process. However, according to the doctor, everything depends on the person. “I think that on the contrary, a higher emotional background contributes to an increase in immunity,” the specialist said. Full Article Health
cto "Emotional Contagion" a Factor in Senior's Mental Health By www.newswise.com Published On :: Tue, 12 Nov 2024 12:00:35 EST A new study finds that seniors who tend to mirror other people's feelings are more likely to show signs of being anxious or depressed themselves. Full Article
cto Do You Know What the Biggest Risk Factors for Pancreatic Cancer Are? By www.newswise.com Published On :: Tue, 12 Nov 2024 14:50:23 EST Full Article
cto Which Risk Factors Are Linked to Having a Severe Stroke? By www.newswise.com Published On :: Wed, 13 Nov 2024 04:00:00 EST People with conditions or habits such as high blood pressure, an irregular heartbeat called atrial fibrillation, or smoking, not only have a higher risk of stroke, they may also have more severe strokes than people without these risk factors, according to a study published in the November 13, 2024, online issue of Neurology(r), the medical journal of the American Academy of Neurology. Full Article
cto "Emotional Contagion" a Factor in Senior's Mental Health By www.newswise.com Published On :: Tue, 12 Nov 2024 12:00:35 EST A new study finds that seniors who tend to mirror other people's feelings are more likely to show signs of being anxious or depressed themselves. Full Article
cto Do You Know What the Biggest Risk Factors for Pancreatic Cancer Are? By www.newswise.com Published On :: Tue, 12 Nov 2024 14:50:23 EST Full Article
cto A New Milestone in the Study of Octopus Arms By www.newswise.com Published On :: Tue, 12 Nov 2024 17:00:14 EST Newly published research by Grainger Engineers in Mechanical Science and Engineering describes an unprecedented computational model that captures the intricate muscular architecture of an octopus arm. Full Article
cto Which Risk Factors Are Linked to Having a Severe Stroke? By www.newswise.com Published On :: Wed, 13 Nov 2024 04:00:00 EST People with conditions or habits such as high blood pressure, an irregular heartbeat called atrial fibrillation, or smoking, not only have a higher risk of stroke, they may also have more severe strokes than people without these risk factors, according to a study published in the November 13, 2024, online issue of Neurology(r), the medical journal of the American Academy of Neurology. Full Article
cto American Sociological Association Appoints Heather Washington as Executive Director By www.newswise.com Published On :: Mon, 04 Nov 2024 10:00:57 EST The appointment is historic for ASA; Washington is the first person of color, and the first Minority Fellowship Program (MFP) alum named ASA executive director. Full Article
cto Maintaining "Good" Care: An Articulation Work Perspective on Organizational Ethics in the Healthcare Sector By www.newswise.com Published On :: Fri, 08 Nov 2024 09:15:34 EST Full Article
cto Gov't Holds Annual Silicon Valley Expo to Support S. Korean Firms in AI, Digital Sectors By world.kbs.co.kr Published On :: Sat, 28 Sep 2024 16:35:08 +0900 [Science] : The government held an annual conference and exhibition at Silicon Valley in the U.S. to give support to South Korean firms in the AI and digital sectors making inroads into the U.S. market. According to the ICT ministry on Saturday, the two-day K-Global@Silicon Valley 2024, marking its 13th year, ...[more...] Full Article Science
cto Actor Yoo Teo included in Gold House's 2024 A100 List By world.kbs.co.kr Published On :: 2024-05-03 Actor Yoo Teo has been included in the 2024 version of Gold House's 'The A100' list.The list, announced every May, nominates 100 of the world's most impactful Asian Pacific leaders in American culture...[more...] Full Article
cto STAYC to Make Comeback in October By world.kbs.co.kr Published On :: 2024-10-08 +09:00 STAYC will be making a comeback this month. The group’s label, High Up Entertainment, has confirmed that the group will be making a comeback on October 30. It added that the group is...[more...] Full Article Economy&It
cto 83,000 Jobs Added in October, Slowest Growth in 4 Months By world.kbs.co.kr Published On :: Wed, 13 Nov 2024 08:29:45 +0900 [Economy] : The nation added 83-thousand jobs in October, with job growth falling below 100-thousand for the first time in four months. According to Statistics Korea on Wednesday, the number of employed people stood at 28-point-eight million last month, up 83-thousand from the same month last year. Job growth fell ...[more...] Full Article Economy
cto Import Prices Jump 2.2% in October, Largest Gain in 6 Months By world.kbs.co.kr Published On :: Wed, 13 Nov 2024 09:13:48 +0900 [Economy] : The country’s import prices jumped more than two percent in October due to the won’s depreciation against the U.S. dollar and a rise in global oil prices. According to data from the Bank of Korea on Wednesday, the country’s import price index reached 137-point-61 in October, up two-point-two ...[more...] Full Article Economy
cto Analytical models representing X-ray form factors of ions By journals.iucr.org Published On :: 2024-01-01 Parameters in analytical models for X-ray form factors of ions f0(s), based on the inverse Mott–Bethe formula involving a variable number of Gaussians, are determined for a wide range of published data sets {s, f0(s)}. The models reproduce the calculated form-factor values close to what is expected from a uniform statistical distribution with limits determined by their precision. For different ions associated with the same atom, the number of Gaussians in the models decreases with increasing net positive charge. Full Article text
cto Parameterized absorptive electron scattering factors By journals.iucr.org Published On :: 2024-01-25 In electron diffraction, thermal atomic motion produces incoherent scattering over a relatively wide angular range, which appears as a diffuse background that is usually subtracted from measurements of Bragg spot intensities in structure solution methods. The transfer of electron flux from Bragg spots to diffuse scatter is modelled using complex scattering factors f + if' in the Bloch wave methodology. In a two-beam Einstein model the imaginary `absorptive' scattering factor f' can be obtained by the evaluation of an integral containing f over all possible scattering angles. While more sophisticated models of diffuse scatter are widely used in the electron microscopy community, it is argued in this paper that this simple model is appropriate for current structure solution and refinement methods. The two-beam model is a straightforward numerical calculation, but even this simplistic approach can become time consuming for simulations of materials with large numbers of atoms in the unit cell and/or many incident beam orientations. Here, a parameterized form of f' is provided for 103 elements as neutral, spherical atoms that reduces calculation time considerably. Full Article text
cto Instrumental broadening and the radial pair distribution function with 2D detectors By journals.iucr.org Published On :: 2024-07-15 The atomic pair distribution function (PDF) is a real-space representation of the structure of a material. Experimental PDFs are obtained using a Fourier transform from total scattering data which may or may not have Bragg diffraction peaks. The determination of Bragg peak resolution in scattering data from the fundamental physical parameters of the diffractometer used is well established, but after the Fourier transform from reciprocal to direct space, these contributions are harder to identify. Starting from an existing definition of the resolution function of large-area detectors for X-ray diffraction, this approach is expanded into direct space. The effect of instrumental parameters on PDF peak resolution is developed mathematically, then studied with modelling and comparison with experimental PDFs of LaB6 from measurements made in different-sized capillaries. Full Article text
cto Human transforming growth factor β type I receptor in complex with kinase inhibitor SB505124 By journals.iucr.org Published On :: 2024-10-23 The crystal structure of the intracellular domain of transforming growth factor β type I receptor (TβR1) in complex with the competitive inhibitor SB505124 is presented. The study provides insights into the structure and function of TβR1 in complex with SB505124, and as such offers molecular-level understanding of the inhibition of this critical signalling pathway. The potential of SB505124 as an avenue for therapy in cancer treatment is discussed on basis of the results. Full Article text
cto Characterization and calibration of DECTRIS PILATUS3 X CdTe 2M high-Z hybrid pixel detector for high-precision powder diffraction measurements By journals.iucr.org Published On :: The performance of a high-Z photon-counting detector for powder diffraction measurements at high (>50 keV) energies is characterized, and the appropriate corrections are described in order to obtain data of higher quality than have previously been obtained from 2D detectors in these energy ranges. Full Article text
cto Crystal structure of N-terminally hexahistidine-tagged Onchocerca volvulus macrophage migration inhibitory factor-1 By journals.iucr.org Published On :: N-terminally hexahistidine-tagged O. volvulus macrophage migration inhibitory factor-1 has a unique jellyfish-like structure with the prototypical macrophage migration inhibitory factor trimer as the `head' and a C-terminal extension as the `tail'. Full Article text
cto Influence of device configuration and noise on a machine learning predictor for the selection of nanoparticle small-angle X-ray scattering models By journals.iucr.org Published On :: 2024-09-23 Small-angle X-ray scattering (SAXS) is a widely used method for nanoparticle characterization. A common approach to analysing nanoparticles in solution by SAXS involves fitting the curve using a parametric model that relates real-space parameters, such as nanoparticle size and electron density, to intensity values in reciprocal space. Selecting the optimal model is a crucial step in terms of analysis quality and can be time-consuming and complex. Several studies have proposed effective methods, based on machine learning, to automate the model selection step. Deploying these methods in software intended for both researchers and industry raises several issues. The diversity of SAXS instrumentation requires assessment of the robustness of these methods on data from various machine configurations, involving significant variations in the q-space ranges and highly variable signal-to-noise ratios (SNR) from one data set to another. In the case of laboratory instrumentation, data acquisition can be time-consuming and there is no universal criterion for defining an optimal acquisition time. This paper presents an approach that revisits the nanoparticle model selection method proposed by Monge et al. [Acta Cryst. (2024), A80, 202–212], evaluating and enhancing its robustness on data from device configurations not seen during training, by expanding the data set used for training. The influence of SNR on predictor robustness is then assessed, improved, and used to propose a stopping criterion for optimizing the trade-off between exposure time and data quality. Full Article text
cto xrdPlanner: exploring area detector geometries for powder diffraction and total scattering experiments By journals.iucr.org Published On :: 2024-02-02 xrdPlanner is a software package designed to aid in the planning and preparation of powder X-ray diffraction and total scattering beam times at synchrotron facilities. Many modern beamlines provide a flexible experimental setup and may have several different detectors available. In combination with a range of available X-ray energies, it often makes it difficult for the user to explore the available parameter space relevant for a given experiment prior to the scheduled beam time. xrdPlanner was developed to provide a fast and straightforward tool that allows users to visualize the accessible part of reciprocal space of their experiment at a given combination of photon energy and detector geometry. To plan and communicate the necessary geometry not only saves time but also helps the beamline staff to prepare and accommodate for an experiment. The program is tailored toward powder X-ray diffraction and total scattering experiments but may also be useful for other experiments that rely on an area detector and for which detector placement and achievable momentum-transfer range are important experimental parameters. Full Article text
cto Determination of optimal experimental conditions for accurate 3D reconstruction of the magnetization vector via XMCD-PEEM By journals.iucr.org Published On :: 2024-02-19 This work presents a detailed analysis of the performance of X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) as a tool for vector reconstruction of magnetization. For this, 360° domain wall ring structures which form in a synthetic antiferromagnet are chosen as the model to conduct the quantitative analysis. An assessment is made of how the quality of the results is affected depending on the number of projections that are involved in the reconstruction process, as well as their angular distribution. For this a self-consistent error metric is developed which allows an estimation of the optimum azimuthal rotation angular range and number of projections. This work thus proposes XMCD-PEEM as a powerful tool for vector imaging of complex 3D magnetic structures. Full Article text
cto Quantifying bunch-mode influence on photon-counting detectors at SPring-8 By journals.iucr.org Published On :: 2024-02-16 Count-loss characteristics of photon-counting 2D detectors are demonstrated for eight bunch-modes at SPring-8 through Monte Carlo simulations. As an indicator, the effective maximum count rate was introduced to signify the X-ray intensity that the detector can count with a linearity of 1% or better after applying a count-loss correction in each bunch-mode. The effective maximum count rate is revealed to vary depending on the bunch-mode and the intrinsic dead time of the detectors, ranging from 0.012 to 0.916 Mcps (megacounts per second) for a 120 ns dead time, 0.009 to 0.807 Mcps for a 0.5 µs dead time and 0.020 to 0.273 Mcps for a 3 µs intrinsic detector dead time. Even with equal-interval bunch-modes at SPring-8, the effective maximum count rate does not exceed 1 Mcps pixel−1. In other words, to obtain data with a linearity better than 1%, the maximum intensity of X-rays entering the detector should be reduced to 1 Mcps pixel−1 or less, and, in some cases, even lower, depending on the bunch-mode. When applying count-loss correction using optimized dead times tailored to each bunch-mode, the effective maximum count rate exceeds the values above. However, differences in the effective maximum count rate due to bunch-modes persist. Users of photon-counting 2D detectors are encouraged to familiarize themselves with the count-loss characteristics dependent on bunch-mode, and to conduct experiments accordingly. In addition, when designing the time structure of bunch-modes at synchrotron radiation facilities, it is essential to take into account the impact on experiments using photon-counting 2D detectors. Full Article text
cto Wavefront analysis and phase correctors design using SHADOW By journals.iucr.org Published On :: 2024-04-23 Knife-edge imaging is a successful method for determining the wavefront distortion of focusing optics such as Kirkpatrick–Baez mirrors or compound refractive lenses. In this study, the wavefront error of an imperfect elliptical mirror is predicted by developing a knife-edge program using the SHADOW/OASYS platform. It is shown that the focusing optics can be aligned perfectly by minimizing the parabolic and cubic coefficients of the wavefront error. The residual wavefront error provides precise information about the figure/height errors of the focusing optics suggesting it as an accurate method for in situ optical metrology. A Python program is developed to design a customized wavefront refractive corrector to minimize the residual wavefront error. Uniform beam at and out of focus and higher peak intensity are achieved by the wavefront correction in comparison with ideal focusing. The developed code provides a quick way for wavefront error analysis and corrector design for non-ideal optics especially for the new-generation diffraction-limited sources, and saves considerable experimental time and effort. Full Article text
cto Self-calibration strategies for reducing systematic slope measurement errors of autocollimators in deflectometric profilometry By journals.iucr.org Published On :: 2024-06-05 Deflectometric profilometers are used to precisely measure the form of beam shaping optics of synchrotrons and X-ray free-electron lasers. They often utilize autocollimators which measure slope by evaluating the displacement of a reticle image on a detector. Based on our privileged access to the raw image data of an autocollimator, novel strategies to reduce the systematic measurement errors by using a set of overlapping images of the reticle obtained at different positions on the detector are discussed. It is demonstrated that imaging properties such as, for example, geometrical distortions and vignetting, can be extracted from this redundant set of images without recourse to external calibration facilities. This approach is based on the fact that the properties of the reticle itself do not change – all changes in the reticle image are due to the imaging process. Firstly, by combining interpolation and correlation, it is possible to determine the shift of a reticle image relative to a reference image with minimal error propagation. Secondly, the intensity of the reticle image is analysed as a function of its position on the CCD and a vignetting correction is calculated. Thirdly, the size of the reticle image is analysed as a function of its position and an imaging distortion correction is derived. It is demonstrated that, for different measurement ranges and aperture diameters of the autocollimator, reductions in the systematic errors of up to a factor of four to five can be achieved without recourse to external measurements. Full Article text
cto High-throughput and high-resolution powder X-ray diffractometer consisting of six sets of 2D CdTe detectors with variable sample-to-detector distance and innovative automation system By journals.iucr.org Published On :: 2024-06-20 The demand for powder X-ray diffraction analysis continues to increase in a variety of scientific fields, as the excellent beam quality of high-brightness synchrotron light sources enables the acquisition of high-quality measurement data with high intensity and angular resolution. Synchrotron powder diffraction has enabled the rapid measurement of many samples and various in situ/operando experiments in nonambient sample environments. To meet the demands for even higher throughput measurements using high-energy X-rays at SPring-8, a high-throughput and high-resolution powder diffraction system has been developed. This system is combined with six sets of two-dimensional (2D) CdTe detectors for high-energy X-rays, and various automation systems, including a system for automatic switching among large sample environmental equipment, have been developed in the third experimental hutch of the insertion device beamline BL13XU at SPring-8. In this diffractometer system, high-brilliance and high-energy X-rays ranging from 16 to 72 keV are available. The powder diffraction data measured under ambient and various nonambient conditions can be analysed using Rietveld refinement and the pair distribution function. Using the 2D CdTe detectors with variable sample-to-detector distance, three types of scan modes have been established: standard, single-step and high-resolution. A major feature is the ability to measure a whole powder pattern with millisecond resolution. Equally important, this system can measure powder diffraction data with high Q exceeding 30 Å−1 within several tens of seconds. This capability is expected to contribute significantly to new research avenues using machine learning and artificial intelligence by utilizing the large amount of data obtained from high-throughput measurements. Full Article text
cto The effect of transport apertures on relay-imaged, sharp-edged laser profiles in photoinjectors and the impact on electron beam properties By journals.iucr.org Published On :: 2024-06-06 In a photoinjector electron source, the initial transverse electron bunch properties are determined by the spatial properties of the laser beam on the photocathode. Spatial shaping of the laser is commonly achieved by relay imaging an illuminated circular mask onto the photocathode. However, the Gibbs phenomenon shows that recreating the sharp edge and discontinuity of the cut profile at the mask on the cathode is not possible with an optical relay of finite aperture. Furthermore, the practical injection of the laser into the photoinjector results in the beam passing through small or asymmetrically positioned apertures. This work uses wavefront propagation to show how the transport apertures cause ripple structures to appear in the transverse laser profile even when effectively the full laser power is transmitted. The impact of these structures on the propagated electron bunch has also been studied with electron bunches of high and low charge density. With high charge density, the ripples in the initial charge distribution rapidly wash-out through space charge effects. However, for bunches with low charge density, the ripples can persist through the bunch transport. Although statistical properties of the electron bunch in the cases studied are not greatly affected, there is the potential for the distorted electron bunch to negatively impact machine performance. Therefore, these effects should be considered in the design phase of accelerators using photoinjectors. Full Article text
cto PEPICO analysis of catalytic reactor effluents towards quantitative isomer discrimination: DME conversion over a ZSM-5 zeolite By journals.iucr.org Published On :: 2024-06-25 The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts – zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors. However, GC is not suitable for the detection of highly reactive intermediates such as ketene or formaldehyde and is not suitable for kinetic studies under well defined low pressure conditions. Photoelectron–photoion coincidence (PEPICO) spectroscopy has emerged as a powerful analytical tool for unraveling complex compositions of catalytic effluents, but its availability is limited to a handful of facilities worldwide. Herein, PEPICO analysis of catalytic reactor effluents has been implemented at the FinEstBeAMS beamline of MAX IV Laboratory. The conversion of dimethyl ether (DME) on a zeolite catalyst (ZSM-5-MFI27) is used as a prototypical model reaction producing a wide distribution of hydrocarbon products. Since in zeolites methanol is quickly equilibrated with DME, this reaction can be used to probe vast sub-networks of the full MTH process, while eliminating or at least slowing down methanol-induced secondary reactions and catalyst deactivation. Quantitative discrimination of xylene isomers in the effluent stream is achieved by deconvoluting the coincidence photoelectron spectra. Full Article text
cto Indirect detector for ultra-high-speed X-ray micro-imaging with increased sensitivity to near-ultraviolet scintillator emission By journals.iucr.org Published On :: 2024-08-28 Ultra-high-speed synchrotron-based hard X-ray (i.e. above 10 keV) imaging is gaining a growing interest in a number of scientific domains for tracking non-repeatable dynamic phenomena at spatio-temporal microscales. This work describes an optimized indirect X-ray imaging microscope designed to achieve high performance at micrometre pixel size and megahertz acquisition speed. The entire detector optical arrangement has an improved sensitivity within the near-ultraviolet (NUV) part of the emitted spectrum (i.e. 310–430 nm wavelength). When combined with a single-crystal fast-decay scintillator, such as LYSO:Ce (Lu2−xYxSiO5:Ce), it exploits the potential of the NUV light-emitting scintillators. The indirect arrangement of the detector makes it suitable for high-dose applications that require high-energy illumination. This allows for synchrotron single-bunch hard X-ray imaging to be performed with improved true spatial resolution, as herein exemplified through pulsed wire explosion and superheated near-nozzle gasoline injection experiments at a pixel size of 3.2 µm, acquisition rates up to 1.4 MHz and effective exposure time down to 60 ps. Full Article text
cto meso-5,15-Bis[3-(isopropylidenegalactopyranoxy)phenyl]-10,20-bis(4-methylphenyl)porphyrin By journals.iucr.org Published On :: 2024-10-24 The crystal structure of a glycosylated porphyrin (P_Gal2) system, C70H70N4O12, where two isopropylidene protected galactose moieties are attached to the meso position of a substituted tetraaryl porphyrin is reported. This structure reveals that the parent porphyrin is planar, with the galactose moieties positioned above and below the porphyrin macrocycle. This orientation likely prevents porphyrin–porphyrin H-type aggregation, potentially enhancing its efficiency as a photosensitizer in photodynamic therapy. Notable non-bonding C—H⋯O and C—H⋯π interactions among adjacent P_Gal2 systems are observed in this crystal network. Additionally, the tolyl groups of each porphyrin can engage in π–π interactions with the delocalized π-systems of neighboring porphyrins. Full Article text
cto Crystal clear: the impact of crystal structure in the development of high-performance organic semiconductors By journals.iucr.org Published On :: 2024-10-31 Full Article text
cto Factors affecting macromolecule orientations in thin films formed in cryo-EM By journals.iucr.org Published On :: 2024-06-27 The formation of a vitrified thin film embedded with randomly oriented macromolecules is an essential prerequisite for cryogenic sample electron microscopy. Most commonly, this is achieved using the plunge-freeze method first described nearly 40 years ago. Although this is a robust method, the behaviour of different macromolecules shows great variation upon freezing and often needs to be optimized to obtain an isotropic, high-resolution reconstruction. For a macromolecule in such a film, the probability of encountering the air–water interface in the time between blotting and freezing and adopting preferred orientations is very high. 3D reconstruction using preferentially oriented particles often leads to anisotropic and uninterpretable maps. Currently, there are no general solutions to this prevalent issue, but several approaches largely focusing on sample preparation with the use of additives and novel grid modifications have been attempted. In this study, the effect of physical and chemical factors on the orientations of macromolecules was investigated through an analysis of selected well studied macromolecules, and important parameters that determine the behaviour of proteins on cryo-EM grids were revealed. These insights highlight the nature of the interactions that cause preferred orientations and can be utilized to systematically address orientation bias for any given macromolecule and to provide a framework to design small-molecule additives to enhance sample stability and behaviour. Full Article text
cto Transferable Hirshfeld atom model for rapid evaluation of aspherical atomic form factors By journals.iucr.org Published On :: 2024-03-01 Form factors based on aspherical models of atomic electron density have brought great improvement in the accuracies of hydrogen atom parameters derived from X-ray crystal structure refinement. Today, two main groups of such models are available, the banks of transferable atomic densities parametrized using the Hansen–Coppens multipole model which allows for rapid evaluation of atomic form factors and Hirshfeld atom refinement (HAR)-related methods which are usually more accurate but also slower. In this work, a model that combines the ideas utilized in the two approaches is tested. It uses atomic electron densities based on Hirshfeld partitions of electron densities, which are precalculated and stored in a databank. This model was also applied during the refinement of the structures of five small molecules. A comparison of the resulting hydrogen atom parameters with those derived from neutron diffraction data indicates that they are more accurate than those obtained with the Hansen–Coppens based databank, and only slightly less accurate than those obtained with a version of HAR that neglects the crystal environment. The advantage of using HAR becomes more noticeable when the effects of the environment are included. To speed up calculations, atomic densities were represented by multipole expansion with spherical harmonics up to l = 7, which used numerical radial functions (a different approach to that applied in the Hansen–Coppens model). Calculations of atomic form factors for the small protein crambin (at 0.73 Å resolution) took only 68 s using 12 CPU cores. Full Article text
cto Dynamical refinement with multipolar electron scattering factors By journals.iucr.org Published On :: 2024-03-21 Dynamical refinement is a well established method for refining crystal structures against 3D electron diffraction (ED) data and its benefits have been discussed in the literature [Palatinus, Petříček & Corrêa, (2015). Acta Cryst. A71, 235–244; Palatinus, Corrêa et al. (2015). Acta Cryst. B71, 740–751]. However, until now, dynamical refinements have only been conducted using the independent atom model (IAM). Recent research has shown that a more accurate description can be achieved by applying the transferable aspherical atom model (TAAM), but this has been limited only to kinematical refinements [Gruza et al. (2020). Acta Cryst. A76, 92–109; Jha et al. (2021). J. Appl. Cryst. 54, 1234–1243]. In this study, we combine dynamical refinement with TAAM for the crystal structure of 1-methyluracil, using data from precession ED. Our results show that this approach improves the residual Fourier electrostatic potential and refinement figures of merit. Furthermore, it leads to systematic changes in the atomic displacement parameters of all atoms and the positions of hydrogen atoms. We found that the refinement results are sensitive to the parameters used in the TAAM modelling process. Though our results show that TAAM offers superior performance compared with IAM in all cases, they also show that TAAM parameters obtained by periodic DFT calculations on the refined structure are superior to the TAAM parameters from the UBDB/MATTS database. It appears that multipolar parameters transferred from the database may not be sufficiently accurate to provide a satisfactory description of all details of the electrostatic potential probed by the 3D ED experiment. Full Article text
cto On the structure refinement of metal complexes against 3D electron diffraction data using multipolar scattering factors By journals.iucr.org Published On :: 2024-08-15 This study examines various methods for modelling the electron density and, thus, the electrostatic potential of an organometallic complex for use in crystal structure refinement against 3D electron diffraction (ED) data. It focuses on modelling the scattering factors of iron(III), considering the electron density distribution specific for coordination with organic linkers. We refined the structural model of the metal–organic complex, iron(III) acetylacetonate (FeAcAc), using both the independent atom model (IAM) and the transferable aspherical atom model (TAAM). TAAM refinement initially employed multipolar parameters from the MATTS databank for acetylacetonate, while iron was modelled with a spherical and neutral approach (TAAM ligand). Later, custom-made TAAM scattering factors for Fe—O coordination were derived from DFT calculations [TAAM-ligand-Fe(III)]. Our findings show that, in this compound, the TAAM scattering factor corresponding to Fe3+ has a lower scattering amplitude than the Fe3+ charged scattering factor described by IAM. When using scattering factors corresponding to the oxidation state of iron, IAM inaccurately represents electrostatic potential maps and overestimates the scattering potential of the iron. In addition, TAAM significantly improved the fitting of the model to the data, shown by improved R1 values, goodness-of-fit (GooF) and reduced noise in the Fourier difference map (based on the residual distribution analysis). For 3D ED, R1 values improved from 19.36% (IAM) to 17.44% (TAAM-ligand) and 17.49% (TAAM-ligand-Fe3+), and for single-crystal X-ray diffraction (SCXRD) from 3.82 to 2.03% and 1.98%, respectively. For 3D ED, the most significant R1 reductions occurred in the low-resolution region (8.65–2.00 Å), dropping from 20.19% (IAM) to 14.67% and 14.89% for TAAM-ligand and TAAM-ligand-Fe(III), respectively, with less improvement in high-resolution ranges (2.00–0.85 Å). This indicates that the major enhancements are due to better scattering modelling in low-resolution zones. Furthermore, when using TAAM instead of IAM, there was a noticeable improvement in the shape of the thermal ellipsoids, which more closely resembled those of an SCXRD-refined model. This study demonstrates the applicability of more sophisticated scattering factors to improve the refinement of metal–organic complexes against 3D ED data, suggesting the need for more accurate modelling methods and highlighting the potential of TAAM in examining the charge distribution of large molecular structures using 3D ED. Full Article text
cto Crystal structure of N-terminally hexahistidine-tagged Onchocerca volvulus macrophage migration inhibitory factor-1 By journals.iucr.org Published On :: 2024-11-06 Onchocerca volvulus causes blindness, onchocerciasis, skin infections and devastating neurological diseases such as nodding syndrome. New treatments are needed because the currently used drug, ivermectin, is contraindicated in pregnant women and those co-infected with Loa loa. The Seattle Structural Genomics Center for Infectious Disease (SSGCID) produced, crystallized and determined the apo structure of N-terminally hexahistidine-tagged O. volvulus macrophage migration inhibitory factor-1 (His-OvMIF-1). OvMIF-1 is a possible drug target. His-OvMIF-1 has a unique jellyfish-like structure with a prototypical macrophage migration inhibitory factor (MIF) trimer as the `head' and a unique C-terminal `tail'. Deleting the N-terminal tag reveals an OvMIF-1 structure with a larger cavity than that observed in human MIF that can be targeted for drug repurposing and discovery. Removal of the tag will be necessary to determine the actual biological oligomer of OvMIF-1 because size-exclusion chomatographic analysis of His-OvMIF-1 suggests a monomer, while PISA analysis suggests a hexamer stabilized by the unique C-terminal tails. Full Article text
cto Structural determination of oleanane-28,13β-olide and taraxerane-28,14β-olide fluorolactonization products from the reaction of oleanolic acid with SelectfluorTM By journals.iucr.org Published On :: 2024-07-15 The X-ray crystal structure data of 12-α-fluoro-3β-hydroxyolean-28,13β-olide methanol hemisolvate, 2C30H47FO3·CH3OH, (1), and 12-α-fluoro-3β-hydroxytaraxer-28,14β-olide methanol hemisolvate, 2C30H47FO3·CH3OH, (2), are described. The fluorolactonization of oleanolic acid using SelectfluorTM yielded a mixture of the six-membered δ-lactone (1) and the unusual seven-membered γ-lactone (2) following a 1,2-shift of methyl C-27 from C-14 to C-13. Full Article text