检索结果-内蒙古大学图书馆

How Intermolecular Interaction and Hydrostatic Pressure Affect the Organic Room Temperature Phosphorescence Properties: A Qm/Mm Study

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Xu, Yuanyuan Pang, Kunwei Song, Yuzhi Lin, Lili Wang, Chuan-Kui Fan, Jianzhong Shandong Province Key Laboratory of Medical Physics and Image Processing Technology School of Physics and Electronics Shandong Normal University Jinan250014 China School of Science Qilu University of Technology Shandong Academy of Sciences Jinan250353 China State Key Laboratory of Luminescent Materials and Devices South China University of Technology China

Stimulus-responsive organic room temperature phosphorescence (RTP) materials with luminescence properties (such as color, efficiency and lifetime) changed with force, heat, light, electric filed, etc., have drawn increasing attention for their broad applications in the fields of sensors, bioimaging and organic light emitting diodes (OLEDs). Especially, the hydrostatic pressure effects on excited state properties of RTP molecules are conspicuous. However, the relationship among structure, hydrostatic pressure and RTP properties is unclear, corresponding theoretical investigations are highly desired. Herein, on the basis of density functional theory (DFT) and time-dependent density functional theory (TD-DFT), combined with the quantum mechanics/molecular mechanics (QM/MM) and the thermal vibration correlation function (TVCF) methods, the influence of methyl substitution effect and hydrostatic pressure effect on the photophysical properties of five isomers (O-PTZ-1Me-H (ax), O-PTZ-2Me-H (ax), O-PTZ-H (eq), O-PTZ-H-1Me (eq) and O-PTZ-H-2Me (eq)) is investigated theoretically. Results reveal that molecules with quasi-equatorial (eq) conformation have superior spin-orbit coupling (SOC) effects and more restricted geometric changes than molecules with quasi-axial (ax) conformation. In particular, the O-PTZ-H-1Me (eq) molecule has a minimum reorganization energy (429.16 meV) due to strong intermolecular interactions, significantly inhibits the non-radiative transition process (3.05×103 s-1), and exhibits a maximum intersystem crossing (ISC) rate (6.02×108 s-1) for efficient triplet exciton generation. In addition, the RTP properties of O-PTZ-H-1Me (eq) are sensitive to hydrostatic pressure, and the quantum efficiency and lifetime are impressively improved by applying high hydrostatic pressure. Because of the small reorganization energy (562.80 meV) and SOC constant (3.98 cm-1) at 0 Gpa, the minimum non-radiative rate (2.64×101 s-1) is achieved, resulting in a 64-fold (44.24

关键词： Hydrostatic pressure

Spiral Scanning and Self-Supervised image Reconstruction Enable Ultra-Sparse Sampling Multispectral Photoacoustic Tomography

学校读者我要写书评

暂无评论

arXiv

arXiv 2024年

作者： Zhong, Yutian Zhang, Xiaoming Mo, Zongxin Zhang, Shuangyang Chen, Wufan Qi, Li School of Biomedical Engineering Southern Medical University Guangdong Guangzhou China Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangdong Guangzhou China Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology Southern Medical University Guangdong Guangzhou China

Multispectral photoacoustic tomography (PAT) is an imaging modality that utilizes the photoacoustic effect to achieve non-invasive and high-contrast imaging of internal tissues. However, the hardware cost and computational demand of a multispectral PAT system consisting of up to thousands of detectors are huge. To address this challenge, we propose an ultra-sparse spiral sampling strategy for multispectral PAT, which we named U3S-PAT. Our strategy employs a sparse ring-shaped transducer that, when switching excitation wavelengths, simultaneously rotates and translates. This creates a spiral scanning pattern with multispectral angle-interlaced sampling. To solve the highly ill-conditioned image reconstruction problem, we propose a self-supervised learning method that is able to introduce structural information shared during spiral scanning. We simulate the proposed U3S-PAT method on a commercial PAT system and conduct in vivo animal experiments to verify its performance. The results show that even with a sparse sampling rate as low as 1/30, our U3S-PAT strategy achieves similar reconstruction and spectral unmixing accuracy as non-spiral dense sampling. Given its ability to dramatically reduce the time required for three-dimensional multispectral scanning, our U3S-PAT strategy has the potential to perform volumetric molecular imaging of dynamic biological activities. Copyright © 2024, The Authors. All rights reserved.

关键词： image reconstruction

Medical image Fusion for High-Level Analysis: A Mutual Enhancement Framework for Unaligned PAT and MRI

学校读者我要写书评

暂无评论

arXiv

arXiv 2024年

作者： Zhong, Yutian He, Jinchuan Liang, Zhichao Zhang, Shuangyang Feng, Qianjin Lu, Lijun Qi, Li School of Biomedical Engineering Southern Medical University Guangdong Guangzhou China Guangdong Provincial Key Laboratory of Medical Image Processing Southern Medical University Guangdong Guangzhou China Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology Southern Medical University Guangdong Guangzhou China

Photoacoustic tomography (PAT) offers optical contrast, whereas magnetic resonance imaging (MRI) excels in imaging soft tissue and organ anatomy. The fusion of PAT with MRI holds promising application prospects due to their complementary advantages. Existing image fusion have made considerable progress in pre-registered images, yet spatial deformations are difficult to avoid in medical imaging scenarios. More importantly, current algorithms focus on visual quality and statistical metrics, thus overlooking the requirements of high-level tasks. To address these challenges, we propose an unsupervised fusion model, termed PAMRFuse+, which integrates image generation and registration. Specifically, a cross-modal style transfer network is introduced to simplify cross-modal registration to single-modal registration. Subsequently, a multi-level registration network is employed to predict displacement vector fields. Furthermore, a dual-branch feature decomposition fusion network is proposed to address the challenges of cross-modal feature modeling and decomposition by integrating modality-specific and modality-shared features. PAMRFuse+ achieves satisfactory results in registering and fusing unaligned PAT-MRI datasets. Moreover, for the first time, we evaluate the performance of medical image fusion with multi-organ instance segmentation. Extensive experimental demonstrations reveal the advantages of PAMRFuse+ in improving the performance of medical image analysis tasks. Copyright © 2024, The Authors. All rights reserved.

关键词： image fusion

Exploration of Narrowband Red Multiple-Resonance Thermally Activated Delayed Fluorescence Molecules Via Donor Engineering Strategy on B-Π-B Framework

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Zhao, Xin Liu, Huanling Song, Yuzhi Lin, Lili Xu, Yuanyuan Wang, Chuan-Kui Fan, Jianzhong Shandong Province Key Laboratory of Medical Physics and Image Processing Technology School of Physics and Electronics Shandong Normal University Jinan250014 China School of Science Qilu University of Technology Shandong Academy of Sciences Jinan250353 China State Key Laboratory of Luminescent Materials and Devices South China University of Technology China

The exploration of reducing the full-width at half-maximum (FWHM) without enlarging energy gaps (∆EST) in red multi-resonance thermally activated delayed fluorescence (MR TADF) molecule is highly demanded. Herein, based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations coupled with the thermal vibration correlation function (TVCF) method, we study the excited-state properties and luminescence mechanisms of two reported TADF molecules (PXZ-R-BN and BCz-R-BN). Drawing inspiration from these, we theoretically design four novel red MR TADF molecules by donor engineering strategy with increased electron donation abilities and extended π-conjugations. To accurately predict the excited state energies of these MR TADF molecules, we employ the range-separated double hybrid density functional (B2PLYP), effectively refine the ∆EST values. Results show that different donor groups influence the frontier molecular orbitals, thereby reducing the energy gaps. These adjustments effectively optimize the energy levels and transition properties of the excited states, leading to the substantial acceleration the reverse intersystem crossing (RISC) processes. Furthermore, the designed molecules with extended π-conjugations not only possess small reorganization energies but also minimal nuclear displacements, coupled with short-range charge transfer characteristics. These features contribute significantly to the narrowband emissions. Therefore, it is verified that these four novel red MR TADF molecules strike favorable balance between the ∆EST and the FWHM values. Meanwhile, the intrinsic relationship between molecular structures and photophysical properties is elucidated, paving the way for the development of novel and efficient red MR TADF emitters. © 2024, The Authors. All rights reserved.

关键词： Energy gap

Exploration of Narrowband Red Multiple-Resonance Thermally Activated Delayed Fluorescence Molecules Via Donor Engineering Strategy on B-Π-B Framework

学校读者我要写书评

暂无评论

SSRN 2024年

关键词： Molecular orbitals

Remote Sensing image Object Detection Method with Feature Denoising Fusion Module

学校读者我要写书评

暂无评论

Remote Sensing Image Object Detection Method with Feature De...

IEEE Advanced Information Technology, Electronic and Automation Control Conference (IAEAC)

作者： Penghui Chen Qishen Li Qiufeng Li Zhongyu Wu School of Information Engineering Nanchang Hangkong University Nanchang Jiangxi China Key Laboratory of Jiangxi Province for Image Processing and Pattern Recognition Nanchang Jiangxi China School of Software Nanchang Hangkong University Nanchang Jiangxi China Key Laboratory of Nondestructive Testing (Ministry of Education) Nanchang Hangkong University Nanchang Jiangxi China

Remote sensing object detection is an important research area in computer vision, widely applied in both military and civilian domains. However, challenges in remote sensing image object detection such as large image sizes, complex backgrounds, and significant variations in target scales are prevalent. To address these issues, this paper proposes a new Feature Denoising and Fusion Module (FDFM) aimed at enhancing the accuracy and robustness of object detection. This module comprises a Multi-Scale Denoising Submodule(MDS) and an Attention Optimization Submodule(AOS). The Multi-Scale Denoising Module aims to suppress lower-level texture noise by utilizing higher-level semantic features before the fusion process, reducing the impact of lower-level noise on subsequent multi-scale feature fusion. Meanwhile, the Attention Optimization Module seeks to enhance the precision of self-attention computations within the Multi-Scale Denoising Module without increasing the parameter count. The efficacy of this method was evaluated on public datasets DOTA, VisDrone, VOC and COCO, showing improvements in comparison to baseline models.

关键词：

Theoretical Study on the Influence of Substitution Position on the Luminescence Properties and Charge Transfer Characteristics of Thermally Activated Delayed Fluorescent Molecules

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Zhang, Kai Wang, XiaoFei Cai, Lei Fan, Jianzhong Wang, Chuan-Kui Lin, Lili School of Physics and Physical Engineering Qufu Normal University Qufu273165 China Shandong Province Key Laboratory of Medical Physics and Image Processing Technology School of Physics and Electronics Shandong Normal University Jinan250014 China

Thermally active delayed fluorescence (TADF) molecules have potentially applications in organic light-emitting diodes (OLEDs) and biomedical sensing. Although TADF emitters have witnessed a rapid development, it remains challenging to study the relationship between molecular structures and luminescence properties as well as carrier mobility transfer properties in theory. In this work, the photophysical properties and luminescence mechanisms of isomers TPA-APQDCN-C (donors at para-position) and TPA-APQDCN-Y (donors at ortho-position) were studied based on density functional theory (DFT) and thermal vibration correlation function (TVCF) method. The results showed that both TPA-APQDCN-C with para-substitued donor and TPA-APQDCN-Y with ortho-substituted donors exhibit red emission in toluene and crystal state. Furthermore, compared to ortho-substituted donors, para-substituted donors promote a redshift in emission wavelength. In addition, the fluorescence efficiencies of TPA-APQDCN-C is obviously higher than that of TPA-APQDCN-Y due to its larger radiative rate and less non-radiative decay rate. Besides, para-substitution (TPA-APQDCN-C) leads to the smaller energy gap between and and the larger spin-orbit coupling (SOC) constant, which is beneficial for increasing the reverse crossing intersystem (RISC) rates. In addition, the carrier mobilities are studied based on the kinetic Monte Carlo simulations. The calculations show that TPA-APQDCN-C are more beneficial for the transfer of holes compared to TPA-APQDCN-Y. This study reveals TPA-APQDCN-C with donors at para-position has a better TADF properties and hole transfer ability, which holds guiding significance for the design of TADF devices with high luminescence efficiency and rapid hole transfer. © 2023, The Authors. All rights reserved.

关键词： Isomers

Decomposing and Coupling Saliency Map for Lesion Segmentation in Ultrasound images

学校读者我要写书评

暂无评论

arXiv

arXiv 2023年

作者： Ning, Zhenyuan Mao, Yixiao Feng, Qianjin Zhong, Shengzhou Zhang, Yu School of Biomedical Engineering Southern Medical University Guangdong Guangzhou510515 China Guangdong Provincial Key Laboratory of Medical Image Processing The Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology Southern Medical University Guangzhou510515 China

Complex scenario of ultrasound image, in which adjacent tissues (i.e., background) share similar intensity with and even contain richer texture patterns than lesion region (i.e., foreground), brings a unique challenge for accurate lesion segmentation. This work presents a decomposition-coupling network, called DC-Net, to deal with this challenge in a (foreground-background) saliency map disentanglement-fusion manner. The DC-Net consists of decomposition and coupling subnets, and the former preliminarily disentangles original image into foreground and background saliency maps, followed by the latter for accurate segmentation under the assistance of saliency prior fusion. The coupling subnet involves three aspects of fusion strategies, including: 1) regional feature aggregation (via differentiable context pooling operator in the encoder) to adaptively preserve local contextual details with the larger receptive field during dimension reduction;2) relation-aware representation fusion (via cross-correlation fusion module in the decoder) to efficiently fuse low-level visual characteristics and high-level semantic features during resolution restoration;3) dependency-aware prior incorporation (via coupler) to reinforce foreground-salient representation with the complementary information derived from background representation. Furthermore, a harmonic loss function is introduced to encourage the network to focus more attention on low-confidence and hard samples. The proposed method is evaluated on two ultrasound lesion segmentation tasks, which demonstrates the remarkable performance improvement over existing state-of-the-art methods. Copyright © 2023, The Authors. All rights reserved.

关键词： Textures

MGTN: Multi-scale Graph Transformer Network for 3D Point Cloud Semantic Segmentation

学校读者我要写书评

暂无评论

MGTN: Multi-scale Graph Transformer Network for 3D Point Clo...

IEEE Visual communications and image processing (VCIP)

作者： Da Ai Siyu Qin Zihe Nie Hui Yuan Ying Liu Xi’an Key Laboratory of Image Processing Technology and Applications for Public Security Xi’an University of Posts and Telecommunications Xi’an China School of Communication and Information Engineering Xi’an University of Posts and Telecommunications Xi’an China School of Control Science and Engineering Shandong University Jinan China

ISBN: (数字)9798331529543

ISBN: (纸本)9798331529550

The structural similarity of point clouds presents challenges in accurately recognizing and segmenting semantic information at the demarcation points of complex scenes or objects. In this study, we propose a multi-scale graph transformer network (MGTN) for 3D point cloud semantic segmentation. First, a multi-scale graph convolution (MSG-Conv) is devised to address the limitations faced by existing methods when extracting local and global features of point cloud data with varying densities simultaneously. Subsequently, we employ a graph-transformer (G-T) module to enhance edge details and spatial position information in the point cloud, thereby improving recognition accuracy for small objects and confusing elements such as columns and beams. Extensive testing on ShapeNet parts and S3DIS datasets was conducted to demonstrate the effectiveness of MGTN. Compared to the baseline network DGCNN, our proposed MGTN achieves substantial performance improvements, as evidenced by notable increases in mIoU of 1.5% and 18.5% on the ShapeNet parts and S3DIS datasets respectively. Additionally, MGTN outperforms the recent CFSA- Net by 2.3% and 3.4% on OA and mIoU respectively.

关键词： Point cloud compression Three-dimensional displays Visual communication Convolution Semantic segmentation Semantics Transformers Feature extraction Data mining Testing