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Reaction mechanism of methyl nitrite dissociation during co catalytic coupling to dimethyl oxalate:A density functional theory study

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Chinese Journal of Chemical Engineering 2016年第1期24卷 132-139页

作者： Chen Fan Man Luo wende xiao Key Laboratory of Advanced Control and Optimization for Chemical Processes Ministry of Education East China University of Science and Technology (ECUST) School of Chemistry and Chemical Engineering Shanghai Jiao Tong University (SJTU)

Dissociation of methyl nitrite is the first step during CO catalytic coupling to dimethyl oxalate followed by hydrogenation to ethyl glycol in a typical coal to liquid process. In this work, the first-principle calculations based on density functional theory were performed to explore the reaction mechanism for the non-catalytic dissociation of methyl nitrite in the gas phase and the catalytic dissociation of methyl nitrite on Pd(111) surface since palladium supported on alpha-alumina is the most effective catalyst for the coupling. For the non-catalytic case, the calculated results show that the CH_3O–NO bond will break with a bond energy of 1.91 eV, and the produced CH_3O radicals easily decompose to formaldehyde, while the further dissociation of formaldehyde in the gas phase is difficult due to the strong C–H bond. On the other hand, the catalytic dissociation of methyl nitrite on Pd(111) to the adsorbed CH_3O and NO takes place with a small energy barrier of 0.03 eV. The calculated activation energies along the proposed reaction pathways indicate that(i) at low coverage, a successive dehydrogenation of the adsorbed CH_3O to CO and H is favored while(ii) at high coverage, hydrogenation of CH_3O to methanol and carbonylation of CH_3O to methyl formate are more preferred. On the basis of the proposed reaction mechanism,two meaningful ways are proposed to suppress the dissociation of methyl nitrate during the CO catalytic coupling to dimethyl oxalate.

关键词： Methyl nitrite Catalytic Non-catalytic Dissociation Density functional theory

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Construction of two-dimensional hydrogen clusters on Au（111） directed by phthalocyanine molecules

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Nano Research 2014年第1期7卷 79-84页

作者： Kai Yang wende xiao Liwei Liu Xiangmin Fei Hui Chen Shixuan Du Hong-Jun Gao Institute of Physics Chinese Academy of Sciences Beijing 100190 China

Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anchored on the Au（111） surface to efficiently collect and pin hydrogen molecules. A two-dimensional （2D） molecular hydrogen cluster is formed around the MnPc. The hydrogen cluster exhibits bias-dependent topography and spatial-dependent conductance spectra, which are rationalized by the exponentially decreasing threshold energy with distance from the central MnPc to activate the motion of the H2 molecules. This exponential drop reveals an interfacial phase behavior in the 2D cluster.

关键词： hydrogen manganese phthalocyanine Au(111) interfacial phase scanning tunnelingmicroscopy

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Recovery of edge states of graphene nanoislands on an iridium substrate by silicon intercalation

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Nano Research 2018年第7期11卷 3722-3729页

作者： Hui Chen Yande Que Lei Tao Yu-Yang Zhang xiao Lin wende xiao Dongfei Wang Shixuan Du Sokrates T. Pantelides Hong-Jun Gao Institute of Physics & University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing 100190 China Department of Physics and Astronomy Vanderbilt University Nashville Tennessee 37235 USA Department of Electrical Engineering and Computer Science Vanderbilt University Nashville Tennessee 3723S USA

Finite-sized graphene sheets, such as graphene nanoislands （GNIs）, are promising candidates for practical applications in graphene-based nanoelectronics. GNIs with well-defined zigzag edges are predicted to have spin-polarized edge-states similar to those of zigzag-edged graphene nanoribbons, which can achieve graphene spintronics. However, it has been reported that GNIs on metal substrates have no edge states because of interactions with the substrate. We used a combination of scanning tunneling microscopy, spectroscopy, and density functional theory calculations to demonstrate that the edge states of GNIs on an Ir substrate can be recovered by intercalating a layer of Si atoms between the GNIs and the substrate. We also found that the edge states gradually shift to the Fermi level with increasing island size. This work provides a method to investigate spin-polarized edge states in high-quality graphene nanostructures on a metal substrate.

关键词： graphene nanoisland zigzag edge edge state scanning tunneling microscopy density functional theory

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Fabrication and manipulation of nanosized graphene homojunction with atomically-controlled boundaries

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Nano Research 2020年第12期13卷 3286-3291页

作者： Hui Chen De-Liang Bao Dongfei Wang Yande Que wende xiao Yu-Yang Zhang Jiatao Sun Shixuan Du Hong-Jun Gao Institute of Physics and University of Chinese Academy of Sciences Beijing100190China CAS Key Laboratory of Vacuum Physics University of Chinese Academy of SciencesBeijing100049China

Controlling the atomic configurations of structural defects in graphene nanostructures is crucial for achieving desired ***,we report the controlled fabrication of high-quality single-crystal and bicrystal graphene nanoislands(GNI)through a unique top-down etching and post-annealing procedure on a graphite ***-temperature scanning tunneling microscopy(STM)combined with density functional theory calculations reveal that most of grain boundaries(GBs)formed on the bicrystal GNIs are 5-7-5-7 *** nanodomains separated by a 5-7-5-7 GB are AB stacking and twisted stacking with respect to the underlying graphite substrate and exhibit distinct electronic properties,forming a graphene *** addition,we construct homojunctions with alternative AB/twisted stacking nanodomains separated by parallel 5-7-5-7 ***,the stacking orders of homojunctions are manipulated from AB/twist into twist/twist type through a STM *** controllable fabrication and manipulation of graphene homojunctions with 5-7-5-7 GBs and distinct stacking orders open an avenue for the construction of GBs-based devices in valleytronics and twistronics.

关键词： homojunction graphene nanoislands manipulations grain boundaries twisted stacking

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Densely packed overlayer of iron phthalocyanine molecules grown on single-layer graphene

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Chinese Chemical Letters 2018年第1期29卷 183-186页

作者： Liwei Liu wende xiao Jinhai Mao Haigang Zhang YuhangJiang Haitao Zhou Kai Yang Hongjun Gao Institute of Physics Chinese Academy of Sciences Beijing 100190 China Beijing Institute of Technology Beijing 100081 China

The formation of densely packed overlayer of iron phthalocyanine （FePc） molecules on single-layer graphene （SLG） epitaxially grown on Ru（0001） is studied by means of low temperature scanning tunneling microscopy. We show that the FePc molecules form single molecular arrays, ordered honeycomb lattice, Kagome lattice and square lattice with increasing molecular coverage. The densely packed square lattice of the molecular layer is modulated by the moire pattern of SLGJRu（O001）. The superposition of the square lattice of the molecular layer on the hexagonal lattice of SLG molte pattern leads to the formation of a larger strip moire pattern. This coverage-dependent self-assembling behavior of FePc on SLG/Ru（0001 ） is mainly driven by the inhomogeneous electronic structure of graphene moire oattern, due to soatial-deoendent interracial charge transfer between SLG and Ru（0001 ） substrate.

关键词： Self-assemblyCoverage-dependentMetal phthalocyanineGrapheneScanning tunneling microscopy

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Phenomenological models of diffusivities based on local composition

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化工进展 2011年第S2期30卷 30-35页

作者： YAN Jianmin,xiao wende (School of Chemistry and Chemical Engineering,Shanghai JiaoTong University,Shanghai 200240)

In phenomenological models,diffusivity is at least a function of composition and the diffusivities at infinite *** additional parameter(?),which can be determined by diffusivity in midpoint,are specially brought forward as token of fractional friction related with the interactions of same molecules in this paper,to extrapolate a new correlative equation for the mutual Maxwell-Stefan ***,the correlative equation can be extended to calculate diffusivities in multicomponent mixtures based on binary data *** theoretical calculations are evaluated with published experimental *** M-S diffusivities in a three-component liquid system are regarded as binary coefficients,the predictive results also agree with the experimental *** indicate that the model with additional coefficients is superior to currently used Darken methods,especially for systems of polar organic-water and those containing associative component.

关键词： diffusivity diffusion phenomenological models Maxwell-Stefan’s law

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Bandgap broadening at grain boundaries in single-layer MoS2

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Nano Research 2018年第11期11卷 6102-6109页

作者： Dongfei Wang Hua Yu Lei Tao wende xiao Peng Fan Tingting Zhang Mengzhou Liao Wei Guo Dongxia Shi Shixuan Du Guangyu Zhang Hongjun Gao Institute of Physics & University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing I00190 China School of Physics Beijing Institute of Technology Beijing 10008 I China

Two-dimensional semiconducting transition-metal dichalcogenides have attracted considerable interest owing to their unique physical properties and future device applications. In particular, grain boundaries (GBs) have been often observed in single-layer MoS2 grown via chemical vapor deposition, which can significantly influence the material properties. In this study, we examined the electronic structures of various GBs in single-layer MoS2 grown on highly oriented pyrolytic graphite using low-temperature scanning tunneling microscopy/spectroscopy. By measuring the local density of states of a series of GBs with tilt angles ranging from 0° to 25°, we found that the bandgaps at the GBs can be either broadened or narrowed with respect to the intrinsic single-layer MoS2. The bandgap broadening shows that the GBs can become more insulating, which may directly influence the transport properties of nanodevices based on polycrystalline single-layer MoS2 and be useful for optoelectronics.

关键词： MoS 2 grain boundary bandgap scanning tunneling microscopy

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Clinical Outcomes and Prehabilitation Strategies of Patients Treated with Cement-Screw Technique for Tibial Defects in Total Knee Arthroplasty

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Journal of Biosciences and Medicines 2023年第12期11卷 27-39页

作者： Weikun Zheng Junfen Tang Xinliang Wang wende xiao Department of Orthopedics Nansha Hospital Guangzhou First People’s Hospital Guangzhou China The First Clinical College of Medicine Jinan University Jinan China School of Medicine South China University of Technology Guangzhou China Department of Neurology Nansha Hospital Guangzhou First People’s Hospital Guangzhou China Department of Orthopedics Guangzhou First People’s Hospital Guangzhou China

Objective: To investigate the clinical efficacy of the cement-screw technique in repairing tibial plateau bone defects in total knee arthroplasty (TKA) recipients and summarize the preoperative prehabilitation strategies for such surgeries. Methods: A total of 33 TKA recipients (45 knees) in our department underwent repair of unilateral or bilateral tibial defects using the cement-screw technique. The subjects were divided into two groups based on the differences in preoperative interventions. The control group received routine preoperative health education according to the consensus, while the observation group received instructive and standardized prehabilitation exercises for four weeks in addition to the routine education. Scale scores, intraoperative parameters, and postoperative recovery indicators were recorded at different time pointsand subjected to statistical analysis for intra-group and inter-group differences. All subjects underwent long-term follow-up for at least 24 months. Results: Within each group at different time points, there were statistically significant differences in VAS, ROM, and HSS scores (p Conclusions: Cement-screw technique for repairing tibial plateau bone defects in TKA recipients can significantly relieve pain, and improve joint function. Prehabilitation can improve preoperative rehabilitation reserves in these patients, accelerate postoperative recovery, and contribute to better short-term clinical outcomes.

关键词： Cement-Screw Technique Total Knee Arthroplasty Tibial Bone Defect Prehabilitation

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Treatment of Pathological Fractures of the Proximal Femur Due to Advanced Metastasis of Highly Malignant Tumors: A Clinical Controlled Study of Enterostenosis Reconstruction and Conservative Treatment

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Journal of Biosciences and Medicines 2020年第8期8卷 127-137页

作者： Weikun Zheng Junfen Tang wende xiao Weishan Cai Department of Orthopedics Guangzhou First People’s Hospital Guangzhou China Department of Neurology Guangzhou First People’s Hospital Guangzhou China

Objective: To investigate whether different treatment methods have an impact on the quality of life and life span after fracture of patients with proximal femoral pathological fractures caused by advanced metastasis of highly malignant tumors. Methods: Karnofsky performance status (KPS) and visual analogue score (VAS) were counted at the time of admission and 2 months after the treatments. Survival analysis was implemented to compare the median survival time and 6-month survival rate of the 2 groups. Musculoskeletal score (MSTS) was used to evaluate limb function in the surgical group at 2 months after the treatment. Results: There was no significant difference in KPS score and VAS score between the two groups at the time of admission (p > 0.05). At 2 months after treatment, the KPS score of the surgical group was higher than that of the conservative group (P Conclusion: Surgical intervention can benefit patients with pathological fractures of the proximal femur due to metastasis of highly malignant tumors in terms of quality of life and survival. Local tumor resection and endoparasitic replacement, which can be tolerated by most patients, can effectively reconstruct the limb function of these patients and restore their self-care ability.

关键词： Malignant Tumors Proximal Femoral Pathological Fracture Endoparasitic Proximal Femoral Replacement Conservative Treatment

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碳酸乙烯酯和乙醇均相酯交换反应研究

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化学反应工程与工艺 2006年第5期22卷 418-423页

作者：赵献萍肖文德华东理工大学化学工程国家重点实验室上海200237

研究了以乙醇钠为均相催化剂,碳酸乙烯酯和乙醇酯交换合成碳酸二乙酯同时联产乙二醇的过程。考察了催化剂浓度、醇酯比、温度等因素对反应的影响,得到较适宜的工艺条件。以加成-消除机理为基础,分别以两步亲核加成基元反应为速率控制步... 详细信息

研究了以乙醇钠为均相催化剂,碳酸乙烯酯和乙醇酯交换合成碳酸二乙酯同时联产乙二醇的过程。考察了催化剂浓度、醇酯比、温度等因素对反应的影响,得到较适宜的工艺条件。以加成-消除机理为基础,分别以两步亲核加成基元反应为速率控制步骤,提出了两个动力学模型,用Runge-Kutta法和非线性最小二乘法估计了相应的模型参数。统计检验表明,两个模型在所研究的压力、温度和组分的浓度范围内均是适用的。

关键词：碳酸二乙酯酯交换碳酸乙烯酯均相反应乙醇钠动力学

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