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Direct growth of tungsten oxide nanorods from heated tungsten foils

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Science China(Technological Sciences) 2012年第6期55卷 1503-1508页

作者： qin JingFang ZHANG GengMin xing YingJie Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics Peking UniversityBeijing 100871China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijing 100871China

Tungsten oxide （W18O49） nanorods were grown by directly heating tungsten foils covered with potassium bromide （KBr） in low-pressure wet oxygen. The approach featured such advantages as convenient manipulation, low cost and rapid accessibility to high temperatures. A solid-liquid-solid （SLS） mechanism is believed to have dominated the growth process, in which the W18049 nanorods segregated from eutectic droplets of potassium tungstate and tungsten oxide. The ultraviolet photoelectron spectroscopy （UPS） analysis disclosed that the valence band maximum （VBM） of these nanorods was approximately 9 eV be- low the vacuum level. The feasibility of using the such-fabricated nanorods as field emitters was tested and the related mecha- nism was also discussed.

关键词： W18049 fast heating CVD field emission

A Sequential Converted Measurement Kalman Filter with Doppler Measurements in ECEF Coordinate System

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Chinese Journal of Electronics 2016年第1期25卷 139-145页

作者： WU Weihua JIANG Jing FENG Xun qin xing Air Force Early Warning Academy

When there is the correlation between Doppler and slant range, previous literatures have presented some sequential filter algorithms. However, they are only applied to simplified fixed radar’ s local coordinate system. As a result, a Sequential converted measurement Kalman filter(SCMKF) with Doppler measurements based on the Earth centered earth fixed(ECEF) coordinate system applicable to a moving airborne platform which has time varying attitude is proposed. Firstly, the correlated Doppler and range are decorrelated using the Cholesky factorization, then the converted position measurements are obtained by a series of coordinate transformation with unchanged range component and other observations, such as azimuth and elevation angles; the corresponding error covariances are derived which are used to the Converted measurement Kalman filter(CMKF).Finally the sequential filter is implemented for changed pseudo-Doppler measurements. The proposed method is validated through Monte Carlo test compared with the performance of CMKF with just converted position measurements and traditional SCMKF with Doppler which ignores the correlation between Doppler and range noises,and the conclusion is obtained that utilizing Doppler information correctly can improve tracking performance, nevertheless, the improvement gain of filter accuracy is limited,which can provide some references for engineering application.

关键词： Target tracking Sequential filter Range rate Pseudo-Doppler measurements Earth centered earth fixed(ECEF) coordinate system Converted measurement Kalman filter(CMKF) Correlation coefficient

Thermally confined shell coating amplifies the photoacoustic conversion efficiency of nanoprobes

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Nano Research 2016年第12期9卷 3644-3655页

作者： Yujiao Shi Huan qin Sihua Yang Da xing Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science College of Biophotonics South China Normal University Guangzhou 510631 China

Efficient probes/contrast agents are highly desirable for good-performance photoacoustic （PA） imaging, where the PA signal amplitude of a probe is dominated by both its optical absorption and the conversion efficiency from absorbed laser energy to acoustic waves. Nanoprobes have a unique micro- mechanism of PA energy conversion due to the size effect, which, however, has not been quantitatively demonstrated and effectively utilized. Here, we present quantitative simulations of the PA signal production process for plasmon- mediated nanoprobes based on the finite element analysis method, which were performed to provide a deep understanding of their PA conversion micromechanism. Moreover, we propose a method to amplify the PA conversion efficiency of nanoprobes through the use of thermally confined shell coating, which allows the active control of the conversion efficiency beyond that of conventional probes. Additionally, we deduced the dependence of the conversion efficiency on the shell properties. Gold-nanoparticles/polydimethylsiloxane nanocomposites were experimentally synthesized in the form of gel and microfilms to verify our idea and the simulation results agreed with the experiments. Our work paves the way for the rational design and optimization of nanoprobes with improved conversion efficiency.

关键词： photoacousticnanoprobes micromechanism conversion efficiency shell coating

Prevalence of Cannabis Use around the World:A Systematic Review and Meta-Analysis,2000-2024

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China CDC weekly 2024年第25期6卷 597-604,I0013,I0014页

作者： Qianning Wang Zhen qin xing xing He Zhu Zhongwei Jia National Institute of Health Data Science Center for Drug Abuse Prevention and ControlPeking UniversityBeijingChina School of Public Health Peking UniversityBeijingChina

This study aims to perform a systematic review and meta-analysis on the global prevalence of cannabis use to inform drug prevention strategies,policy-making,and resource *** study initially screened 177,843 studies published between January 1,2000,and January 15,2024,using peer-reviewed databases including Web of Science,PubMed,Scopus,Embase,and Cochrane ***,595 studies were identified for data extraction,and 39 of these were selected as country-representative *** among the selected studies was assessed using the chi-squared test and I2 statistic,while sensitivity analysis was conducted to evaluate the robustness of the *** prevalence of cannabis use varied between 0.42%and 43.90%across 33 European countries,1.40%to 38.12%across 15 North and South American countries,0.30%to 19.10%across 16 Asian countries,and 1.30%to 48.70%across 18 Oceania and African *** pooled prevalence of cannabis use was 12.0%[95%confidence interval(CI):10.0,14.3]in countries where cannabis is legalized,compared to 5.4%(95%CI:4.3,6.9)in non-legalized *** findings indicate that the prevalence of cannabis use has disproportionately increased in most countries with the implementation of medical or recreational cannabis legalization policies and relevant geographic *** efforts are needed to monitor newly cannabis-legalized countries and prevent initial use.

关键词： prevention legal initially

Topological Catenation Enhances Elastic Modulus of Single Linear Polycatenane

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Chinese Journal of Polymer Science 2023年第9期41卷 1486-1496,I0009页

作者： Yao-xing Chen Xi-qin Cai Guo-Jie Zhang Department of Chemical Engineering School of Chemistry and Chemical EngineeringGuangzhou UniversityGuangzhou510006China

Entropic elasticity of single chains underlies many fundamental aspects of mechanical properties of polymers,such as high elasticity of polymer networks and viscoelasticity of polymer *** the other hand,single chain elasticity is further rooted in chain ***,mechanically interlocked polymers,including polycatenanes and polyrotaxanes,which are formed by connecting their building blocks(cyclic and linear chains)through topological bonds(e.g.,entanglements),emerge as a conceptually new kind of *** this work,we employ computer simulations to study linear elasticity of single linear polycatenane(or[n]catenane),in which n rings are interlocked through catenation into a chain of linear *** of this work is to illuminate the specific role of catenation topology in the elastic moduli of linear polycatenanes by comparing with those of their[n]bonded-ring counterparts,which are formed by connecting the same number of rings but via covalent *** results lead to a conclusion that topological catenation makes[n]catenanes exhibit larger elastic moduli than their linear and[n]bonded-ring counterparts,i.e.,larger elastic moduli in the case of[n]***,it is revealed that those[n]catenanes composed of a smaller number of rings(smaller n)possesses larger elastic moduli than others of the same total chain *** mechanisms of these findings are discussed based on conformational entropy due to topological constraints.

关键词： Single chain elasticity Polycatenane Computer simulation

Palladium-catalysed diastereodivergent inverse- electron-demand oxa-Diels–Alder reactions of in situ formed cyclopentadienones via ligand- control

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Organic Chemistry Frontiers 2022年第5期9卷 1364-1369页

作者： xing-xing Yang xing-Liang Zhao qin Ouyang Wei Du Ying-Chun Chen Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province and Sichuan Research Center for Drug Precision Industrial TechnologyWest China School of PharmacySichuan UniversityChengdu 610041China College of Pharmacy Third Military Medical UniversityShapingbaChongqing 400038China

Here we report Pd(0)-catalysed asymmetric inverse-electron-demand oxa-Diels–Alder reactions between the carbonates of 4-hydroxy-2-cyclopentenones andα-cyano chalcones by in situ generating η^(2)-Pd(0)-cyclopentadienone complexes as HOMO-raised dienophiles,and diastereodivergent synthesis could be realised by employing a bifunctional monophosphine ligand from a chiral aminoalcohol or a proline-derived bisphosphine ligand.

关键词： inverse Palladium stereo

Dioxygen Affinities and Catalytic Oxidation Performance of Co （Ⅱ） Complexes with Phenol Ether Bridged Dihydroxamic Acids

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Chinese Chemical Letters 2006年第9期17卷 1259-1262页

作者： xing Yue WEI Sheng Ying qin College of Environmental and Biological Engineering Chongqing Technology and Business University Chongqing 400067 Department of Chemistry Sichuan-University Chengdu 610064

The oxygenation constants and thermodynamic parameter （△H°, △S°） of a series of novel Co （Ⅱ） complexes with phenol ether bridged dihydroxamic acids CoL^1-CoL^6 were measured, their catalytic performance in oxidation of p-xylene to p-toluic acid （PTA） were examined. The modulation of O2-binding capabilities and catalytic oxidation activities by X （X = Cl, OCH3） and Y （Y = H, CH3, Cl） groups bonded to the aromatic rings of the Co （Ⅱ） complexes were investigated.

关键词： Cobalt(Ⅱ) complexes dioxygen affinities catalytic oxidation p-xylene

Performance Analysis for Mobile Ad Hoc Network in Random Graph Models with Spatial Reuse

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Acta Mathematicae Applicatae Sinica 2007年第2期23卷 235-244页

作者： Han-xing Wang Xi Hu qin Zhang Department of Mathematics and Statistics Shanghai Lixin University of Commerce Shanghai 201620 China School of Sciences Shanghai University Shanghai 200444 China

In this paper, we present a random graph model with spatial reuse for a mobile ad hoc network （MANET） based on the dynamic source routing protocol. Many important performance parameters of the MANET are obtained, such as the average flooding distance （AFD）, the probability generating function of the flooding distance, and the probability of a flooding route to be symmetric. Compared with the random graph model without spatial reuse, this model is much more effective because it has a smaller value of AFD and a larger probability for finding a symmetric valid route.

关键词： MANETs dynamic source routing probability generating function

An efficient and balanced feature pyramid network: shared-FPN

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Optoelectronics Letters 2025年

作者： Tian Sulong qin Longfei Pang Wenchao Gao Ying Zhao Dexin School of Computer Science and Engineering， Tianjin University of Technology Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology， Tianjin University of Technology

In the field of object detection， it is challenging to achieve a balance between neck complexity and accuracy. To address this issue， we propose an efficient and decoupled neck module called Shared-FPN(Shared Feature Pyramid Network). Our design aims to effectively address the trade-off between these two factors. Neck modules are crucial for effectively fusing multi-scale information in neural network models. However， traditional neck designs， with their single structure， have struggled to significantly improve detection performance. In recent years， the incorporation of neural architecture search techniques in neck design has led to an increase in model complexity. This trade-off between model complexity and detection performance highlights the need for more efficient neck design approaches. Not only does Shared-FPN not increase the number of model parameters and FLOPs， but it also can be easily ported to any of the detection models. It improves on PAFPN by using transposed convolution with a large convolution kernel as the upsampling module， designing spatial pyramidal pooling-fast downsampling(SPPFD) based on shared pooling， and designing shared convolution as the right part module. To evaluate the performance of Shared-FPN in object detection tasks， we conducted experiments on object detection datasets. The results show that Shared-FPN achieved excellent performance across all sizes. In particular， on the VOC 2012 dataset， which contains mostly large objects， Shared-FPN's mAP was improved by 11.2% compared to FPN with YOLOX-s as the detector. On the COCO dataset， which contains mostly small objects， Shared-FPN's mAP was improved by 7.8% compared to FPN and 7.1% compared to PAFPN with Faster RCNN as the detector. Shared-FPN can be easily inserted into any of the detectors for better performance in various scenarios， such as small， medium or large objects.

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