Qingxi Yuan

Bio: Qingxi Yuan is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Phase-contrast imaging & Grating. The author has an hindex of 18, co-authored 79 publications receiving 1176 citations. Previous affiliations of Qingxi Yuan include Brookhaven National Laboratory.

Use of Synchrotron Radiation-Analytical Techniques To Reveal Chemical Origin of Silver-Nanoparticle Cytotoxicity.

Abstract: To predict potential medical value or toxicity of nanoparticles (NPs), it is necessary to understand the chemical transformation during intracellular processes of NPs. However, it is a grand challenge to capture a high-resolution image of metallic NPs in a single cell and the chemical information on intracellular NPs. Here, by integrating synchrotron radiation-beam transmission X-ray microscopy (SR-TXM) and SR-X-ray absorption near edge structure (SR-XANES) spectroscopy, we successfully capture the 3D distribution of silver NPs (AgNPs) inside a single human monocyte (THP-1), associated with the chemical transformation of silver. The results reveal that the cytotoxicity of AgNPs is largely due to the chemical transformation of particulate silver from elemental silver (Ag0)n, to Ag+ ions and Ag–O–, then Ag–S– species. These results provide direct evidence in the long-lasting debate on whether the nanoscale or the ionic form dominates the cytotoxicity of silver nanoparticles. Further, the present approach pr...

Quantification of Heterogeneous Degradation in Li-Ion Batteries

Abstract: DOI: 10.1002/aenm.201900674 rechargeable batteries. Efforts have been devoted to studying different battery components (e.g., cathode, anode, electrolyte, and binder), aiming to improve energy and power densities, enhance safety, prolong lifetime, and reduce cost. An important aspect of the battery research is to identify the fading pathways of battery particles and electrodes at multiple length/time scales under practical operating conditions.[1] Redox reactions in batteries commonly involve phase transformation, lattice volume change, stress buildup, grain boundary weakening, and particle fracturing. These processes intertwine at multiple length and time scales, are termed as the chemomechanical interplay, and contribute to the complex fading mechanisms of composite battery electrodes. Mapping the chemomechanical transformation of battery particles and particle ensembles represents a promising methodology to establish the relationship among all these processes. Such a study will potentially provide insights into designing materials and electrodes where The multiscale chemomechanical interplay in lithium-ion batteries builds up mechanical stress, provokes morphological breakdown, and leads to state of charge heterogeneity. Quantifying the interplay in complex composite electrodes with multiscale resolution constitutes a frontier challenge in precisely diagnosing the fading mechanism of batteries. In this study, hard X-ray phase contrast tomography, capable of nanoprobing thousands of active particles at once, enables an unprecedented statistical analysis of the chemomechanical transformation of composite electrodes under fast charging conditions. The damage heterogeneity is demonstrated to prevail at all length scales, which stems from the unbalanced electron conduction and ionic diffusion, and collectively leads to the nonuniform utilization of active particles spatially and temporally. This study highlights that the statistical mapping of the chemomechanical transformation offers a diagnostic method for the particles utilization and fading, hence could improve electrode formulation for fast-charging batteries.

Automated markerless full field hard x-ray microscopic tomography at sub-50 nm 3-dimension spatial resolution

Abstract: A full field transmission x-ray microscope (TXM) has been developed and commissioned at the National Synchrotron Light Source at Brookhaven National Laboratory. The capabilities we developed in auto-tomography, local tomography, and spectroscopic imaging that overcome many of the limitations and difficulties in existing transmission x-ray microscopes are described and experimentally demonstrated. Sub-50 nm resolution in 3-dimension (3D) with markerless automated tomography has been achieved. These capabilities open up scientific opportunities in many research fields.

A 30 nm-resolution hard X-ray microscope with X-ray fluorescence mapping capability at BSRF

Abstract: A full-field transmission X-ray microscope (TXM) operating continuously from 5 keV to 12 keV with fluorescence mapping capability has been designed and constructed at the Beijing Synchrotron Radiation Facility, a first-generation synchrotron radiation facility operating at 2.5 GeV. Spatial resolution better than 30 nm has been demonstrated using a Siemens star pattern in both absorption mode and Zernike phase-contrast mode. A scanning-probe mode fluorescence mapping capability integrated with the TXM has been shown to provide 50 p. p. m. sensitivity for trace elements with a spatial resolution (limited by probing beam spot size) of 20 mm. The optics design, testing of spatial resolution and fluorescence sensitivity are presented here, including performance measurement results.

Computed tomography algorithm based on diffraction-enhanced imaging setup

Abstract: Recently taking advantage of the novel diffraction-enhanced imaging (DEI) method, one very effective and practical phase contrast imaging technique—a new x-ray computed tomography scheme based on DEI (DEI-CT) showed promising results, really superior to those of conventional CT imaging. In this letter, we show that the application of the conventional CT reconstruction algorithm is not always satisfactory for the new DEI-CT imaging and a new mathematical framework for imaging reconstruction is presented. Experimental data collected at the Beijing synchrotron radiation facility are also discussed using the new algorithm.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Cellular uptake of nanoparticles: journey inside the cell.

Abstract: Nanoscale materials are increasingly found in consumer goods, electronics, and pharmaceuticals. While these particles interact with the body in myriad ways, their beneficial and/or deleterious effects ultimately arise from interactions at the cellular and subcellular level. Nanoparticles (NPs) can modulate cell fate, induce or prevent mutations, initiate cell–cell communication, and modulate cell structure in a manner dictated largely by phenomena at the nano–bio interface. Recent advances in chemical synthesis have yielded new nanoscale materials with precisely defined biochemical features, and emerging analytical techniques have shed light on nuanced and context-dependent nano-bio interactions within cells. In this review, we provide an objective and comprehensive account of our current understanding of the cellular uptake of NPs and the underlying parameters controlling the nano-cellular interactions, along with the available analytical techniques to follow and track these processes.

X-ray phase-contrast imaging: from pre-clinical applications towards clinics

Abstract: Phase-contrast x-ray imaging (PCI) is an innovative method that is sensitive to the refraction of the x-rays in matter. PCI is particularly adapted to visualize weakly absorbing details like those often encountered in biology and medicine. In past years, PCI has become one of the most used imaging methods in laboratory and preclinical studies: its unique characteristics allow high contrast 3D visualization of thick and complex samples even at high spatial resolution. Applications have covered a wide range of pathologies and organs, and are more and more often performed in vivo. Several techniques are now available to exploit and visualize the phase-contrast: propagation- and analyzer-based, crystal and grating interferometry and non-interferometric methods like the coded aperture. In this review, covering the last five years, we will give an overview of the main theoretical and experimental developments and of the important steps performed towards the clinical implementation of PCI.

Silver Nanoparticles: Synthesis and Application for Nanomedicine

Abstract: Over the past few decades, metal nanoparticles less than 100 nm in diameter have made a substantial impact across diverse biomedical applications, such as diagnostic and medical devices, for personalized healthcare practice. In particular, silver nanoparticles (AgNPs) have great potential in a broad range of applications as antimicrobial agents, biomedical device coatings, drug-delivery carriers, imaging probes, and diagnostic and optoelectronic platforms, since they have discrete physical and optical properties and biochemical functionality tailored by diverse size- and shape-controlled AgNPs. In this review, we aimed to present major routes of synthesis of AgNPs, including physical, chemical, and biological synthesis processes, along with discrete physiochemical characteristics of AgNPs. We also discuss the underlying intricate molecular mechanisms behind their plasmonic properties on mono/bimetallic structures, potential cellular/microbial cytotoxicity, and optoelectronic property. Lastly, we conclude this review with a summary of current applications of AgNPs in nanoscience and nanomedicine and discuss their future perspectives in these areas.

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