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arXiv 2024年

作者： Jia, Xiaohan zhang, xuwen School of Mathematics Southeast University Nanjing211189 China Mathematisches Institut Universität Freiburg Ernst-Zermelo-Str.1 Freiburg79104 Germany

In this paper, we prove the quantitative version of the Alexandrov theorem for capillary hypersurfaces in the half-space, which generalizes Julin-Niinikoski’s result [18] to the capillary case. The proof is based on the quantitative analysis of the Montiel-Ros-type argument carried out in our joint works with Wang-Xia [13,14].MSC Codes 53C45, 53A10 Copyright © 2024, The Authors. All rights reserved.

关键词： Capillary tubes

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Adsorption of Orange G on Activated Porous Carbon Derived from Coal Tar Pitch: Experimental and DFT Study

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LANGMUIR 2024年第48期40卷 25471-25482页

作者： Huang, Linlin zhang, xuwen Liu, Tingting Wang, Lin Li, Lixin Li, Da Sheng, Tao Dong, Zilong Zhao, Xinyue Heilongjiang Univ Sci & Technol Coll Environm & Chem Engn Harbin 150022 Peoples R China Harbin Inst Technol State Key Lab Urban Water Resource & Environm Harbin 150000 Peoples R China Northeast Agr Univ Sch Resources & Environm Harbin 150030 Peoples R China

A coal tar pitch-based porous carbon adsorbent (CPA) was synthesized through a straightforward method involving the heating of a mixture of KOH and coal tar pitch (CTP). This CPA exhibited a high surface area of 1811.2 m2 g-1 and a large pore volume of 0.94 cm3 g-1 when prepared with a CTP to KOH mass ratio of 1:4 at 800 degrees C. Parameters such as the heating temperature and activator dose were optimized to enhance the adsorption efficiency. The prepared CPA was extensively characterized by SEM, XRD, FTIR, and BET measurements. Notably, CPA presented a distinct adsorption performance for Orange G (OG), achieving a maximum adsorption capability of 449.7 mg g-1. Kinetic studies indicated that the adsorption process followed the pseudo-second-order model, while the adsorption isotherm data demonstrated that both chemical and physical interactions favored OG adsorption. Thermodynamic analysis revealed that the adsorption of OG on CPA was spontaneous and exothermic and increased the entropy. Density functional theory (DFT) calculations provided insights into the adsorption mechanism, highlighting electrostatic interactions, hydrogen bonds, and pi-pi interactions as the dominant processes governing OG adsorption onto the adsorbent.

关键词： Potassium hydroxide

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Metal-Organic Frameworks-Derived Cobalt Catalyst Supported on Biochar for Efficient Deoxygenation of Stearic Acid

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2025年第4期64卷 2049-2060页

作者： zhang, xuwen Dong, Xuexue Wang, Youting Bian, Juanjuan Ali, Sajid Cai, Dongren Sun, Kang Rao, Xiaoping Jiang, Jianchun Zhan, Guowu Huaqiao Univ Acad Adv Carbon Convers Technol Coll Chem Engn Xiamen 361021 Fujian Peoples R China Huaqiao Univ Fujian Prov Key Lab Biomass Low Carbon Convers Xiamen 361021 Fujian Peoples R China Chinese Acad Forestry CAF Inst Chem Ind Forest Prod Nanjing 210042 Jiangsu Peoples R China

The conversion of stearic acid into linear hydrocarbons is a crucial step in advancing sustainable biofuels and biochemicals. Herein, we developed a series of cobalt-based catalysts (referred to as Co/C@TSC) using metal-organic frameworks (MOFs) as precursors and supporting them on biochar derived from natural tung shells (TSC). Tung shells, a byproduct of the tung oil extraction process, are widely available. The as-designed Co/C@TSC catalyst effectively deoxygenated stearic acid via decarbonylation/decarboxylation (DCO x ) processes, achieving a conversion of 78.5% and hydrocarbon product selectivity of 90%, specifically heptadecane and heptadecene. Our detailed analysis showed that the addition of biochar support improved the spatial distribution of cobalt species (with a high surface concentration of Co0) and enhanced the adsorption of reactants, thus boosting catalytic activity. Additionally, in situ DRIFTS analysis confirmed that the stearic acid deoxygenation process involved the intermolecular dehydration of stearic acid molecules. Experiments with different reaction substrates revealed that the stearic anhydride was a key reaction intermediate during the deoxygenation process. This study introduces a novel catalyst made from dual carbon-supported nonprecious metals, presenting a promising method for transforming stearic acid into valuable hydrocarbon products.

关键词： Reaction intermediates

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A Study of the Influence of Cultural Distance on the Retention of Multinational Exhibitors

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JOURNAL OF QUALITY ASSURANCE IN HOSPITALITY & TOURISM 2024年第1期25卷 22-36页

作者： Cheng, Hongbo zhang, xuwen Li, Ziying Nankai Univ Coll Tourism & Serv Management Tianjin 300350 Peoples R China

Customer retention is an important basis for International Trade shows to obtain sustained competitive advantage, and the retention of multinational exhibitors is largely influenced by cultural heterogeneity. This study intends to explore the influence of cultural distance on the retention of multinational exhibitors based on Hofstede's national culture model. It is based on an analysis of 4476 multinational exhibitors from 7 famous international trade shows in China through web crawler technology. The results reveal that total cultural distance has a significant positive effect on the retention of multinational exhibitors. However, different sub-dimensions under cultural distance may have different effects. In terms of sub-dimensions including power distance, individualism and uncertainty avoidance, the greater the cultural distance, the easier it is to retain customers. As for sub-dimensions of long term orientation, the estimated results display an opposite tendency. The findings contribute to the literature and have practical implications for international trade shows' service and management.

关键词： Cultural distance customer retention international trade show multinational exhibitor

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Experimental Study of the Reinforcement Mechanism for the Tunnel Support Structure in Weak Rock Masses

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INTERNATIONAL JOURNAL OF GEOMECHANICS 2023年第10期23卷 04023173-04023173页

作者： Chen, Yulong zhang, xuwen Qiao, Xuanru China Univ Min & Technol Sch Energy & Min Engn Beijing 100083 Peoples R China

This study aims to comprehensively investigate the reinforcement mechanism of the tunnel support structure and its supporting characteristics in layered and weak rock tunnels. Uniaxial compressive tests were carried out to study the mechanical and deformation characteristics of anchored rock with the system anchor bolt and the steel floral pipe. Besides, a three-point bending test of the steel-concrete composite beam was conducted to investigate the bending capacity of the grilles and I-beams. The experiment showed the following results: (1) The anchor bolt achieved the anchoring effect by improving the stress state and the strength of the surrounding rock. The improvement of the anchorage strength to the surrounding rock was reflected by the effect of the compression zone of preload, the healing effect of the anchorage agent on the surrounding rock, and the reinforcement effect of the anchor bolt on the density and strength of the anchor bolt. (2) By the CT scanning of the anchored samples after the experiment, it was found that the crack was blunted and arrested within the anchorage zone, and the crack-arresting effect was related to the range of the anchorage zone. The larger the anchorage zones, the better the crack-arresting effect. (3) The steel arch could effectively improve the ability of concrete antideformation. Compared with the lattice girder, the coordination ability of steel arch and concrete deformation was relatively weak. Its coordinate deformation stage was shorter than that of the lattice girder and earlier into the debonding stage. However, the stiffness of the steel arch and concrete was greater than that of the lattice girder after debonding and showed a strong bearing capacity.

关键词： Tunnel Support structure Uniaxial test Three-point bend test Anchorage mechanism

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A Two-level Learning Approach for Achieving the Sustainable Development of Service Ecosystem

A Two-level Learning Approach for Achieving the Sustainable ...

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IEEE International Conference on Web Services (IEEE ICWS)

作者： Peng, Chao Xue, Xiao zhang, xuwen Ji, Peilin Shen, Yifan Fang, Li Feng, Zhiyong Tianjin Univ Coll Intelligence & Comp Tianjin Peoples R China Tianjin Key Lab Healthy Habitat & Mart Technol Tianjin Peoples R China Xian Univ Finance & Econ Sch Informat Xian Peoples R China

ISBN: (纸本)9798350368567;9798350368550

The governance of service ecosystem needs to balance efficiency and fairness to promote the sustainable development of the system, making it an important topic. However, service entities in the service ecosystem have autonomy and engage in dynamic game with governance strategies, leading to governance challenges. To address this issue, we model the governance process as a repeated sequential game between the governance algorithm and service entities, and propose a novel two-level learning algorithm. This algorithm considers the learning evolution of service entities and the co-evolutionary of the governance algorithm, using reinforcement learning to learn effective governance strategies while also considering the response function of service entities to balance efficiency and fairness. Combining the ideas of bilevel optimization and online learning, this algorithm effectively balances exploration (understanding the service entities' responses function) and exploitation (choosing efficient actions). We apply the algorithm to a classic service ecosystem, the ride-hailing service system, and empirically demonstrate its effectiveness in the governance task of order dispatching.

关键词： Service Ecosystem Governance Reinforcement Learning Balancing Efficiency and Fairness

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"Twisted" small molecule donors with enhanced intermolecular interactions in the condensed phase towards efficient and thick-film all-small-molecule organic solar cells

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JOURNAL OF MATERIALS CHEMISTRY A 2023年第26期11卷 13984-13993页

作者： Cheng, Xiafei Liang, Ziqi Liang, Shifeng zhang, xuwen Xu, Jie Xu, Yan Ni, Wang Li, Miaomiao Geng, Yanhou Tianjin Univ Sch Mat Sci & Engn Tianjin Key Lab Mol Optoelect Sci Tianjin 300072 Peoples R China Tianjin Inst Power Sources Sci & Technol Power Sources Lab Tianjin 300384 Peoples R China Sinopec Beijing Res Inst Chem Ind Co Ltd Beijing 100013 Peoples R China Joint Sch Natl Univ Singapore & Tianjin Univ Int Campus Tianjin Univ Fuzhou 350207 Peoples R China

How to achieve high crystallinity and suitable phase scale simultaneously from the perspective of molecular engineering remains a long-standing challenge for all-small-molecule organic solar cells (ASM-OSCs). Herein, two small molecule donors, named DRTT-2Se (with two alkylselenophenyl chains) and DRTT-6Se (with six alkylselenophenyl chains), were designed and synthesized by introducing "twisted" backbones and building units with strong intermolecular interactions. The "twisted" skeletons of the molecules can suppress the molecular crystallization and avoid excessive aggregation during the film forming process, while the strong intermolecular interactions of the building units can encourage the formation of ordered molecular packing and nanoscale phase separation via post-treatments. Owing to the enhanced intermolecular interactions induced by alkylselenophenyl side chains, DRTT-2Se and DRTT-6Se with a "twisted" structure displayed more ordered pi-pi packing, and retained the similar nanoscale microstructures in the blend films in comparison to the "twisted" molecule with alkylthiophenyl side chains (DRTT-T), yielding improved hole transport and reduced charge recombination in OSCs. In addition, the alkylselenophenyl substituted molecules showed higher HOMO energy levels, which caused the larger HOMO offset to drive exciton dissociation, but did not increase the energy loss. As a result, the ASM-OSCs based on the selenophene-containing donors exhibited higher FF and J(sc), and similar V-oc, yielding superior PCEs (14.79% and 15.03%) compared to the DRTT-T based device (13.37%). More importantly, the appropriate film morphology made the device efficiency of DRTT-2Se and DRTT-6Se less sensitive to the thickness of active layers. This study provides some implications in designing small molecule donors with suitable crystallization behavior towards high-performance ASM-OSCs.

关键词： Molecules

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Hypothesis paper: electroacupuncture targeting the gut-brain axis to modulate neurocognitive determinants of eating behavior-toward a proof of concept in the obese minipig model

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EATING AND WEIGHT DISORDERS-STUDIES ON ANOREXIA BULIMIA AND OBESITY 2021年第1期26卷 61-74页

作者： zhang, xuwen Chen, Hanwei Val-Laillet, David Panyu Cent Hosp Guangzhou Peoples R China Guanzhou Univ Chinese Med Guangzhou Peoples R China Univ Rennes INRAE INSERM Nutr Metabol & CancNuMeCan 16 Le Clos F-35590 Rennes France

Acupuncture has thousands of years of history and perspective for the treatment of many health problems and disorders. Beneficial effects of acupuncture on obesity have been demonstrated at various levels in animals and clinical trials, with almost no adverse effect, even when combined with local electrical stimulation, i.e., electroacupuncture (EA), a way to potentiate the effects of acupuncture. However, there is still scattered evidence about the impact of EA on brain functions related to the control of eating behavior, and notably on the gut-brain axis mechanisms involved in these putative central modulations. During the past 10 years, we have described a convincing diet-induced obese minipig model, and successfully implemented brain imaging and neurocognitive approaches to challenge mechanistic hypotheses and innovative therapeutic strategies. In the present article, we propose to confront the current literature on the acupuncture and EA effects on the gut-brain axis and obesity with the latest developments in nutrition and neuroscience research using the minipig model. Our aims are to (a) elaborate functional hypotheses on the gut-brain mechanisms underlying EA effects on obesity, and especially on the role of the vagus nerve, and (b) present the rational for testing these hypotheses in the minipig model.

关键词： Obesity Vagus nerve Brain activity Brain imaging Pig model

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STABILITY OF THE WULFF SHAPE WITH RESPECT TO ANISOTROPIC CURVATURE FUNCTIONALS

arXiv

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arXiv 2023年

作者： Scheuer, Julian zhang, xuwen Goethe-Universität Institut für Mathematik Robert-Mayer-Str. 10 Frankfurt60325 Germany School of Mathematical Sciences Xiamen University Xiamen361005 China

For a function f which foliates a one-sided neighbourhood of a closed hypersurface M, we give an estimate of the distance of M to a Wulff shape in terms of the Lp-norm of the traceless F-Hessian of f, where F is the support function of the Wulff shape. This theorem is applied to prove quantitative stability results for the anisotropic Heintze-Karcher inequality, the anisotropic Alexandrov problem, as well as for the anisotropic overdetermined boundary value problem of Serrin-type. Copyright © 2023, The Authors. All rights reserved.

关键词： Boundary value problems

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Collaborative Morphological and Electrical Regulation of High-Mobility Conjugated Polymers via a Multifunctional Polymeric Additive

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MACROMOLECULES 2024年第22期57卷 10792-10801页

作者： Xu, Chenhui An, Chuanbin Gao, Mengyuan zhang, xuwen He, Chunyong Dong, Weijia Wang, Tianzuo Liu, Yuqian Deng, Yunfeng Ye, Long Han, Yang Geng, Yanhou Tianjin Univ Sch Mat Sci & Engn Tianjin Key Lab Mol Optoelect Sci Key Lab Organ Integrated CircuitsMinist Educ Tianjin 300072 Peoples R China Trina Solar State Key Lab Photovolta Sci & Technol Changzhou 213031 Peoples R China Joint Sch Natl Univ Singapore & Tianjin Univ Fuzhou 350207 Peoples R China China Spallat Neutron Source CSNS Spallat Neutron Source Sci Ctr Dongguan 523803 Peoples R China

Morphological and electrical control over conjugated polymers has a great potential for the fabrication of high-performance organic thin-film transistors (OTFTs). Herein, we employed a multifunctional polymeric additive, namely, PBTTT-b-HTPB, to optimize the molecular packing order of an isoindigo-based model polymer (IIDSiC8) and simultaneously regulate the minority carriers for boosted transport properties in OTFTs via facile solution processing. By detailed comparative study, we demonstrated that PBTTT-b-HTPB remarkably improved the crystallinity of IIDSiC8 by forming elongated fibers with higher molecular order in a thin film, which originated from the larger size ordered solution aggregates due to the presence of the insulating block. On the other hand, the p-type conjugated block of PBTTT worked as a hole trapping center, resulting in significantly increased electron density, reduced off-current, and optimal n-type performance. Benefiting from the collaborative morphological and electrical regulation, IIDSiC8/PBTTT-b-HTPB films displayed well-aligned ordered morphology and a high electron mobility up close to 7 cm2 V-1 s-1 together with an on/off ratio of 106 in bar-coated OTFTs. The high electron mobility is among the top performance values reported for isoindigo-based polymers. Our work has achieved simultaneous optimization of film microstructures and carrier transport characteristics of polymer semiconductors, providing opportunities for the production of OTFT devices with a superior performance.

关键词： Conjugated polymers

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