Publications by authors named "Linxi Shi"

Hetero-metal doping or substitution to create alloy clusters is a highly appealing strategy for improving physicochemical characteristics as well as tailoring optical and electronic properties, although high-yield synthesis of alloy clusters with precise positioning of doped metals is a daunting challenge. Herein, we manifest rational synthesis of chiral alloy cluster enantiomers R/S-AgCu in 85 %-87 % yield by replacing one Ag(I) atom with Cu(I) in homometallic clusters R/S-Ag, achieving circularly polarized luminescence (CPL) with a quantum yield beyond 90 %. As a small energy gap (ca.

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As versatile ligands with extraordinary coordination capabilities, RPH (R = alkyl or aryl) are rarely used in constructing metal nanoclusters due to their volatility, toxicity, spontaneous flammability, and susceptibility to oxidation. In this work, we designed a primary and tertiary phosphorus-bound diphosphine chelator (2-PhPCHPH) to create ultrastable silver nanoclusters with metallic aromaticity. By controlling the deprotonation rate of 2-PhPCHPH and adjusting the templates, we successfully synthesized two near-infrared emissive nanoclusters, and , which have analogous icosidodecahedral Ag shells with an symmetry.

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Generating realistic radiographs from CT is mainly limited by the native spatial resolution of the latter. Here we present a general approach for synthesizing high-resolution digitally reconstructed radiographs (DRRs) from an arbitrary resolution CT volume. Our approach is based on an upsampling framework where tissues of interest are first segmented from the original CT volume and then upsampled individually to the desired voxelization (here ~1 mm → 0.

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Conventional fluorescent materials frequently exhibit narrow-band emissions with a small full width at half-maximum (fwhm) due to localized-state characteristics, but electroluminescence is less efficient owing to the utilization of only singlet excitons. In this work, taking advantage of naphthalimide (NAI)-acetylide derivatives with a rigid planar structure and localized transition characteristics, we elaborately designed two mononuclear Pt(II) complexes with weak double emissions of fluorescence and phosphorescence. Taking them as synthetic precursors, we prepared three PtAu heteronuclear clusters and successfully attained highly efficient narrow-band red phosphorescence with the fwhm below 30 nm.

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Necroptosis, a recently discovered form of cell-programmed death that is distinct from apoptosis, has been confirmed to play a significant role in the pathogenesis of bacterial infections in various animal models. Necroptosis is advantageous to the host, but in some cases, it can be detrimental. To understand the impact of necroptosis on the pathogenesis of bacterial infections, we described the roles and molecular mechanisms of necroptosis caused by different bacterial infections in this review.

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Background: Conventional x-ray imaging and fluoroscopy have limitations in quantitation due to several challenges, including scatter, beam hardening, and overlapping tissues. Dual-energy (DE) imaging, with its capability to quantify area density of specific materials, is well-suited to address such limitations, but only if the dual-energy projections are acquired with perfect spatial and temporal alignment and corrected for scatter.

Purpose: In this work, we propose single-shot quantitative imaging (SSQI) by combining the use of a primary modulator (PM) and dual-layer (DL) detector, which enables motion-free DE imaging with scatter correction in a single exposure.

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Background: High precision radiotherapy with small irradiator size has potential in many treatment applications involving small shallow targets, with small animal radio-neuromodulation as an intriguing example. A focused kV technique based on novel usage of polycapillary x-ray lenses can focus x-ray beams to <0.2 mm in diameter, which is ideal for such uses.

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Conventional x-ray imaging provides little quantitative information due to scatter, beam hardening, and overlaying tissues. A single-shot quantitative x-ray imaging (SSQI) method was previously developed to quantify material-specific densities in x-ray imaging by combining the use of a primary modulator (PM) and dual-layer (DL) detector. The feasibility of this concept was demonstrated with simulations using an iterative patch-based method.

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Purpose: Metal artifact remains a challenge in cone-beam CT images. Many image domain-based segmentation methods have been proposed for metal artifact reduction (MAR), which require two-pass reconstruction. Such methods first segment metal from a first-pass reconstruction and then forward-project the metal mask to identify them in projections.

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The focal spot size and shape of an x-ray system are critical factors to the spatial resolution. Conventional approaches to characterizing the focal spot use specialized tools that usually require careful calibration. We propose an alternative to characterize the x-ray source's focal spot, simply using a rotating edge and flat-panel detector.

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Background: Multiple factors contribute to anemia in patients with Hepatitis B virus (HBV)related acute-on-chronic liver failure (ACLF); however, the mechanism is unclear. The purpose of this study was to evaluate the clinical significance of the direct antiglobulin test (DAT) in patients with HBV related ACLF.

Methods: DAT was used to detect immunoglobulins and/or complement proteins on the surface of erythrocytes.

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Highly soluble d-d heteronuclear phosphors afford an alternative approach to achieve high-efficiency organic light-emitting diodes (OLEDs) through a solution process. In this work, four highly phosphorescent d-d heteronuclear complexes with significant Pt-Au interactions were prepared. By judicious selection of sterically hindered and π-conjugated substituents in triphosphine ligands, the phosphorescence is dramatically promoted through effectively prohibiting nonradiative thermal relaxation with an efficiency of 0.

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In this work, rational design of highly soluble and phosphorescent Ag-Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9-carbazole (Hdecz) as a rigid U-shaped ligand with a distinguished hole-transport character. The self-assembly reaction of Hdecz, Au, and Ag generated phosphorescent AgAu cluster (Φ = 0.22 in CHCl) with Hdecz having a free ethynyl (-C≡CH) group.

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Metal-organic frameworks (MOFs) with cuprous-halide-aggregates have shown superiority as organic LED (OLED) and semiconductor materials, while engineering MOF flexibility by involving the expansion of cuprous aggregates remains a great challenge. In this particular work, a dissolution-recrystallization structural transformation (DRST) with the dramatic growth of Cu-I aggregates, from 2D to 3D has been successfully realized. The unsaturated coordination nodes (2-positional nitrogen atoms) in have been demonstrated to be the driven force for DRST to via the formation of coordination bonds.

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Purpose: Dual-energy (DE) x-ray imaging has many clinical applications in radiography, fluoroscopy, and CT. This work characterizes a prototype dual-layer (DL) flat-panel detector (FPD) and investigates its DE imaging capabilities for applications in two-dimensional (2D) radiography/fluoroscopy and quantitative three-dimensional (3D) cone-beam CT. Unlike other DE methods like kV switching, a DL FPD obtains DE images from a single exposure, making it robust against patient and system motion.

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Background: High-resolution, low-noise detectors with minimal dead-space at chest-wall could improve posterior coverage and microcalcification visibility in the dedicated cone-beam breast CT (CBBCT). However, the smaller field-of-view necessitates laterally-shifted detector geometry to enable optimizing the air-gap for x-ray scatter rejection.

Objective: To evaluate laterally-shifted detector geometry for CBBCT with clinical projection datasets that provide for anatomical structures and lesions.

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The size and shape of an x-ray source's focal spot is a critical factor in the imaging system's overall spatial resolution. The conventional approach to imaging the focal spot uses a pinhole camera, but this requires careful, manual measurements. Instead, we propose a novel alternative, simply using the collimator available on many x-ray systems.

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Cone-beam CT (CBCT) is widely used in diagnostic imaging and image-guided procedures, leading to an increasing need for advanced CBCT techniques, such as dual energy (DE) imaging. Previous studies have shown that DE-CBCT can perform quantitative material decomposition, including quantification of contrast agents, electron density, and virtual monoenergetic images. Currently, most CBCT systems perform DE imaging using a kVp switching technique.

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Metal artifact remains a challenge in cone-beam CT images. Many two-pass metal artifact reduction methods have been proposed, which work fairly well, but are limited when the metal is outside the scan field-of-view (FOV) or when the metal is moving during the scan. In the former, even reconstructing with a larger FOV does not guarantee a good estimate of metal location in the projections; and in the latter, the metal location in each projection is difficult to identify due to motion.

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Quantitative short-scan cone beam CT (CBCT) is impeded by streaking and shading artifacts. Streaking artifacts can be caused by approximate handling of data redundancy in short-scan FDK with Parker's weighting, while shading artifacts are caused by scatter and beam hardening effects. In this work, we improve the image quality of short-scan CBCT by removing the streaking artifacts using a previously proposed algorithm in a framework of filtered backprojection with shift-invariant filtering and equal weighting.

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The quantitative use of cone beam computed tomography (CBCT) in radiation therapy is limited by severe shading artifacts, even with system embedded correction. We recently proposed effective shading correction methods, using planning CT (pCT) as prior information to estimate low-frequency errors in either the projection domain or image domain. In this work, we further improve the clinical practicality of our previous methods by removing the requirement of prior pCT images.

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A series of Ag(i) and Cu(i) complexes [Ag3(L1)2][PF6]3 (8), [Ag3(L2)2][PF6]3 (9), [Cu(L1)][PF6] (10) and [Cu(L2)][PF6] (11) have been synthesized by reactions of the tridentate amine-bis(N-heterocyclic carbene) ligand precursors [H2L1][PF6]2 (6) and [H2L2][PF6]2 (7) with Ag2O and Cu2O, respectively. Complexes 10 and 11 can also be obtained by transmetalation of 8 and 9, respectively, with 3.0 equiv.

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Purpose: Dedicated cone beam breast CT (CBBCT) suffers from x-ray scatter contamination. We aim to identify the source of the significant difference between the scatter distributions estimated by two recent methods proposed by our group and to investigate its effect on CBBCT image quality.

Method: We recently proposed two novel methods of scatter correction for CBBCT, using a library based (LB) technique and a forward projection (FP) model.

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Purpose: The quality of dedicated cone-beam breast CT (CBBCT) imaging is fundamentally limited by x-ray scatter contamination due to the large irradiation volume. In this paper, we propose a scatter correction method for CBBCT using a novel forward-projection model with high correction efficacy and reliability.

Method: We first coarsely segment the uncorrected, first-pass, reconstructed CBBCT images into binary-object maps and assign the segmented fibroglandular and adipose tissue with the correct attenuation coefficients based on the mean x-ray energy.

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Purpose: The image quality of cone beam computed tomography (CBCT) is limited by severe shading artifacts, hindering its quantitative applications in radiation therapy. In this work, we propose an image-domain shading correction method using planning CT (pCT) as prior information which is highly adaptive to clinical environment.

Method: We propose to perform shading correction via sparse sampling on pCT.

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