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Diffracted X-ray Blinking Tracks Single Protein Motions
摘要： Single molecule dynamics studies have begun to use quantum probes. Single particle analysis using cryo-transmission electron microscopy has dramatically improved the resolution when studying protein structures and is shifting towards molecular motion observations. X-ray free-electron lasers are also being explored as routes for determining single molecule structures of biological entities. Here, we propose a new X-ray single molecule technology that allows observation of molecular internal motion over long time scales, ranging from milliseconds up to 103 seconds. Our method uses both low-dose monochromatic X-rays and nanocrystal labelling technology. During monochromatic X-ray diffraction experiments, the intensity of X-ray diffraction from moving single nanocrystals appears to blink because of Brownian motion in aqueous solutions. X-ray diffraction spots from moving nanocrystals were observed to cycle in and out of the Bragg condition. Consequently, the internal motions of a protein molecule labelled with nanocrystals could be extracted from the time trajectory using this diffracted X-ray blinking (DXB) approach. Finally, we succeeded in distinguishing the degree of fluctuation motions of an individual acetylcholine-binding protein (AChBP) interacting with acetylcholine (ACh) using a laboratory X-ray source.
关键词： Acetylcholine-binding protein,Brownian motion,Nanocrystal labelling,Single molecule dynamics,X-ray diffraction
更新于2025-09-09 09:28:46
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Interfacing a Potential Purely Organic Molecular Quantum Bit with a Real-Life Surface
摘要： By using a multidisciplinary and multi-technique approach, we have addressed the issue of attaching a molecular quantum bit to a real surface. First, we demonstrate that an organic derivative of the pyrene-Blatter radical is a potential molecular quantum bit. Our study of the interface of the pyrene-Blatter radical with a copper-based surface reveals that the spin of the interface layer is not cancelled by the interaction with the surface and that the Blatter-radical is resistant in presence of molecular water. Although the measured pyrene-Blatter derivative quantum coherence time is not the highest value known, this molecule is known as a “super stable” radical. Conversely, other potential qubits show poor thin film stability upon air exposure. Therefore, we discuss strategies to make molecular systems candidates as qubits competitive, bridging the gap between potential and real applications.
关键词： X-ray spectroscopies,quantum bits,organic radicals,spinterfaces,interfaces
更新于2025-09-09 09:28:46
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Lanthanide-doped Hafnia Nanoparticles for Multimodal Theranostics: Tailoring the Physicochemical Properties and Interactions with Biological Entities
摘要： High-Z metal oxide nanoparticles hold promise as imaging probes and radio-enhancers. Hafnium dioxide nanoparticles have recently entered clinical evaluation. Despite promising early clinical findings, the potential of HfO2 as a matrix for multimodal theranostics is yet to be developed. Here, we investigate the physicochemical properties and the potential of HfO2-based nanoparticles for multimodal theranostic imaging. Undoped and lanthanide (Eu3+, Tb3+, and Gd3+)-doped HfO2 nanoparticles were synthesized and functionalized with various moieties, including poly(vinylpyrrolidone) (PVP), (3-aminopropyl)triethoxysilane (APTES) and folic acid (FA). We show that different synthesis routes, including direct precipitation, microwave-assisted synthesis, and sol-gel chemistry allow preparation of hafnium dioxide particles with distinct physicochemical properties. Sol-gel based synthesis allows preparation of uniform nanoparticles with dopant incorporation efficiencies superior to the other two methods. Both luminescence and contrast properties can be tweaked by lanthanide doping. We show that MRI contrast can be unified with radio-enhancement by incorporating lanthanide dopants in the HfO2 matrix. Importantly, ion leaching from the HfO2 host matrix in lysosomal-like conditions was minimal. For Gd:HfO2 nanoparticles, leaching was reduced >10× compared to Gd2O3 and no relevant cytotoxic effects have been observed in monocyte-derived macrophages for nanoparticle concentrations up to 250 μg/mL. Chemical surface modification allows further tailoring of the cyto- and hemocompatibility and enables functionalization with molecular targeting entities, which lead to enhanced cellular uptake. Taken together, the present study illustrates the manifold properties of HfO2-based nanomaterials with prospective clinical utility beyond radio-enhancement.
关键词： x-ray,magnetic resonance imaging,functionalization,bioimaging,hafnium dioxide
更新于2025-09-09 09:28:46
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Radiation damage free ghost diffraction with atomic resolution
摘要： The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghost diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several ?ngstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.
关键词： atomic resolution,x-ray quantum optics,diffraction imaging
更新于2025-09-09 09:28:46
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A USB 3.0 readout system for Timepix3 detectors with on-board processing capabilities
摘要： Timepix3 is a high-speed hybrid pixel detector consisting of a 256 × 256 pixel matrix with a maximum data rate of up to 5.12 Gbps (80 MHit/s). The ASIC is equipped with eight data channels that are data driven and zero suppressed making it suitable for particle tracking and spectral imaging. In this paper, we present a USB 3.0-based programmable readout system with online pre-processing capabilities. USB 3.0 is present on all modern computers and can, under real-world conditions, achieve around 320 MB/s, which allows up to 40 MHit/s of raw pixel data. With on-line processing, the proposed readout system is capable of achieving higher transfer rate (approaching Timepix4) since only relevant information rather than raw data will be transmitted. The system is based on an Opal Kelly development board with a Spartan 6 FPGA providing a USB 3.0 interface between FPGA and PC via an FX3 chip. It connects to a CERN Timepix3 chipboard with standard VHDCI connector via a custom designed mezzanine card. The firmware is structured into blocks such as detector interface, USB interface and system control and an interface for data pre-processing. On the PC side, a Qt/C++ multi-platform software library is implemented to control the readout system, providing access to detector functions and handling high-speed USB 3.0 streaming of data from the detector. We demonstrate equalisation, calibration and data acquisition using a Cadmium Telluride sensor and optimise imaging data using simultaneous ToT (Time-over-Threshold) and ToA (Time-of-Arrival) information. The presented readout system is capable of other on-line processing such as analysis and classification of nuclear particles with current or larger FPGAs.
关键词： Front-end electronics for detector readout,Detector control systems,X-ray detectors,Data processing methods
更新于2025-09-09 09:28:46
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Performance study of spectroscopic DEPFET arrays with a pixel-wise storage functionality
摘要： To maintain a good spectral performance even at high readout speeds, active pixel sensors like the DEPFET need to be equipped with a storage functionality. Enhancing the frame rate to its limit — the readout time per pixel itself — the charge collection and the readout need to be separated spatially to avoid a signi?cant degradation of the spectral performance. One implementation of a storage concept is the In?nipix DEPFET. The most promising In?nipix variant was investigated in greater detail to study the spectral performance for an array of 32 × 32 pixels. This includes the characterization of the temperature dependence and the contributions of the di?erent noise components. With an optimal set of temperature and timing parameters, a spectrum taken with an iron-55 source was analyzed with high statistics and the energy response for di?erent X-ray photon energies was evaluated.
关键词： X-ray detectors and telescopes,Imaging spectroscopy,Solid state detectors,Detector design and construction technologies and materials
更新于2025-09-09 09:28:46
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Gamma-Ray Dose Measurement with Radio-Photoluminescence Glass Dosimeter in Mixed Radiation Field for BNCT
摘要： Accelerator based neutron sources (ABNS) are being developed as the next generation neutron irradiation system for BNCT. From the ABNS, unnecessary gamma-rays will be generated by neutron capture reactions, as well as fast neutrons. To control the whole-body radiation dose to the patient, measurement of gamma-ray dose in the irradiation room is necessary. In this study, the objective is to establish a method to measure gamma-ray dose separately in a neutron/gamma mixed field by using RPL glass dosimeter. For this purpose, we proposed a lead filter method which uses a pair of RPL glasses with and without a lead filter outside. In order to realize this method, the basic characteristics of glass dosimeter was verified in the gamma-ray field, before adapting it in the mixture field. From the result of the experiment using the lead filter, the simulation result especially for the case with a lead filter overestimated the absorbed does obtained from measurement. We concluded that the reason of the discrepancy is caused by existence of gradient of the dose distribution in the glass, and the difference of sensitivity to low-energy photon between measurement and theory.
关键词： RPL glass dosimeter,BNCT,gamma-ray dose measurement,mixed radiation field,lead filter method
更新于2025-09-09 09:28:46
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Experimental comparison of spherically bent HAPG and Ge crystals
摘要： The Orion high-resolution X-ray (OHREX) imaging spherically bent crystal spectrometer, operated with both image plates and CCD cameras, provides time-averaged plasma diagnostics through high-resolution spectroscopy with good signal-to-noise at the Orion laser facility. In order to provide time-resolved spectra, the OHREX will be out?tted with a streak camera, and in this case, even higher signal to noise will be desired. Using the OHREX’s sister instrument, the EBIT High-resolution X-ray (EBHiX) spectrometer, at the LLNL electron beam ion trap EBIT-I, we therefore compare the ef?ciency of a high-quality Ge (111) crystal (2d = 6.532 ?) with that of a higher integrated re?ectivity, but lower-resolution highly annealed pyrolytic graphite (HAPG) crystal (2d = 6.708 ?) in the energy range 2408–2452 eV. We ?nd that the HAPG provides overall more signal across the entire image; however, because of the much better focusing properties of the Ge crystal, the latter provides more signal within the central 100 μm of the spatial pro?le in the cross-dispersion direction and is thus more suitable for the narrow entrance window of the Livermore-built streak camera.
关键词： HAPG,Ge crystals,X-ray spectroscopy,spherically bent crystals,plasma diagnostics
更新于2025-09-09 09:28:46
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The Warm Electron Beam Ion Trap (WEBIT): An instrument for ground calibration of space-borne x-ray spectrometers
摘要： The warm electron beam ion trap (WEBIT) at Lawrence Livermore National Laboratory is being developed as a pre-launch, ground calibration source for space-borne, high-throughput, high-resolution x-ray spectrometers, such as the x-ray imaging and spectroscopy mission Resolve quantum calorimeter. Historically, calibration sources for calorimeter spectrometers have relied on characteristic line emission from x-ray tubes, fluorescing metals, and radioactive sources. The WEBIT, by contrast, relies on emission from x-ray transitions in highly charged ions, for example, hydrogen-like and helium-like ions, whose energies are well known and whose line shapes are relatively simple. The WEBIT can create astrophysically relevant ions whose x-ray emission falls in the 0.3-12 keV science bandpass of Resolve and has a portable design advantageous for a calibration source. The WEBIT will be used to help calibrate Resolve’s instrumental line shape and gain scale as a function of various operational parameters during both detector subsystem level testing and instrumental level testing.
关键词： calibration source,highly charged ions,x-ray spectrometers,electron beam ion trap,WEBIT
更新于2025-09-09 09:28:46
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[IEEE 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob) - Enschede (2018.8.26-2018.8.29)] 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob) - Application of Convolutional Neural Networks to Femur Tracking in a Sequence of X-Ray Images
摘要： A path along which the human knee joint moves can be estimated from real-time moving images or a sequence of static images. In case of many algorithms solving this problem, it is essential to locate the characteristic points (i.e., key-points) on each image and find the correspondence between them in the image sequence. In this paper we present an algorithm, which detects such key-points facilitating effective femur tracking in a sequence of X-ray images. We use a set of X-ray images manually labeled with the key-point positions, to train a Convolutional Neural Network (CNN) for the purposes of solving a regression task corresponding to finding key-point positions in previously unknown images. CNN hyper-parameters such as number of convolutions and layers, learning rate, regularization parameters, and activation functions were optimized using a tree of Parzen estimators guiding the process of training multiple models. Results for models with the best mean-square estimation error computed for a validation set and lowest structural complexity are presented. Key-point positions predicted by the CNN are on par with human predictions, even though the actual key-point position is ambiguous in some cases. The feasibility of detected key-points for femur tracking has been verified by several case studies.
关键词： key-point detection,femur tracking,medical image analysis,X-ray images,Convolutional Neural Networks
更新于2025-09-09 09:28:46