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Segmented tubular synthesis of monodispersed microsized copper oxalate

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International Journal of Minerals,Metallurgy and Materials 2019年第4期26卷 460-466页

作者： xun liu Xing Chen Kai Huang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing Key Lab of Green Recycling and Extraction of Metals University of Science and Technology Beijing

Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.

关键词： segmented flow tube reactor copper oxalate powder monodispersed scaling-up shape inducer

A hybrid vertex-centered finite volume/element method for viscous incompressible flows on non-staggered unstructured meshes

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Acta Mechanica Sinica 2012年第2期28卷 324-334页

作者： Wei Gao Ru-xun liu Hong Li School of Mathematical Sciences Inner Mongolia University010021 HuhhotChina Department of Mathematics University of Science and Technology of China230026 HefeiChina

This paper proposes a hybrid vertex-centered fi- nite volume/finite element method for solution of the two di- mensional （2D） incompressible Navier-Stokes equations on unstructured grids. An incremental pressure fractional step method is adopted to handle the velocity-pressure coupling. The velocity and the pressure are collocated at the node of the vertex-centered control volume which is formed by join- ing the centroid of cells sharing the common vertex. For the temporal integration of the momentum equations, an im- plicit second-order scheme is utilized to enhance the com- putational stability and eliminate the time step limit due to the diffusion term. The momentum equations are discretized by the vertex-centered finite volume method （FVM） and the pressure Poisson equation is solved by the Galerkin finite el- ement method （FEM）. The momentum interpolation is used to damp out the spurious pressure wiggles. The test case with analytical solutions demonstrates second-order accuracy of the current hybrid scheme in time and space for both veloc- ity and pressure. The classic test cases, the lid-driven cavity flow, the skew cavity flow and the backward-facing step flow, show that numerical results are in good agreement with the published benchmark solutions.

关键词： Incompressible flow Vertex-centered finite vol- ume method Finite element method - Unstructured grid

The Crustal Structure and Assembly of Terranes in the Qaidam-Qilian-Beishan Area, Western China

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Acta Geologica Sinica(English Edition) 1998年第3期72卷 243-255页

作者： liu xun GAO Rui Institute of Geology Chinese Academy of Geological Sciences 26 Baiwanzhuang Rd. Beijing 100037

Abstract: Through a study of the geotransect from Golmud to Ejin Qi published recently, the tectonics of the crust beneath the area from the northern Qinghai-Tibet plateau (Qaidam and the Qilian Mountains) to the border between China and Mongolia and its structure, composition and tectonic evolution have been revealed, and abundant information about the deep structures has been provided. Based on the research into the geotransect, it is suggested that the crust in this area was formed by the assembly of the terranes in different geological stages. Following the formation of the Palaeo-Asian continent, the north part of the corridor of the transect became a part of the huge unifying continent by the end of the Early Permian. In the Mesozoic and Cenozoic, as a result of the compression mainly by the push of the Qinghai-Tibet plateau on the south, the unique crustal structure and geomorphologic features on the northern Qinghai-Tibet plateau were formed. This geotransect together with the Yadong-Golmud geotransect constitutes a long geotransect which runs across the western Chinese continent.

关键词： crustal structure terrane assembly western China

Equivalent low-order angular flux nonlinear finite difference equation of MOC transport calculation

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Nuclear Science and Techniques 2020年第12期31卷 139-151页

作者： Li-xun liu Chen Hao Yun-Lin Xu Fundamental Science On Nuclear Safety and Simulation Technology Laboratory Harbin Engineering UniversityHarbin 150001China Institute of Nuclear and New Energy Technology(INET) Tsinghua UniversityBeijing 100084China Purdue University West LafayetteIN 47907USA

The key issue in accelerating method of characteristics(MOC)transport calculations is in obtaining a completely equivalent low-order neutron transport or diffusion ***,an equivalent low-order angular flux nonlinear finite difference equation is proposed for MOC transport *** method comprises three essential features:(1)the even parity discrete ordinates method is used to build a low-order angular flux nonlinear finite difference equation,and different boundary condition treatments are proposed;(2)two new defined factors,i.e.,the even parity discontinuity factor and odd parity discontinuity factor,are strictly defined to achieve equivalence between the low-order angular flux nonlinear finite difference method and MOC transport calculation;(3)the energy group and angle are decoupled to construct a symmetric linear system that is much easier to *** equivalence of this low-order angular flux nonlinear finite difference equation is analyzed for two-dimensional(2D)pin,2D assembly,and 2D C5G7 benchmark *** results demonstrate that a low-order angular flux nonlinear finite difference equation that is completely equivalent to the pin-resolved transport equation is established.

关键词： Angular flux Equivalence Even parity discrete ordinates method Nonlinear finite difference

Research Article Dynamically crosslinked nanocapsules for the efficient and serumresistant cytosolic protein delivery

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Nano Research 2024年第3期17卷 1760-1771页

作者： Qiang Yang Ningyu liu Ziyin Zhao xun liu Lichen Yin Institute of Functional Nano and Soft Materials(FUNSOM) Jiangsu Key Laboratory of Carbon-Based Functional Materials and DevicesSoochow UniversitySuzhou 215123China Department of Thoracic Surgery The Second Affiliated Hospital of Soochow UniversitySuzhou 215004China

Intracellular protein delivery is critical to the development of protein-based biopharmaceuticals and ***,current delivery vectors often suffer from complicated syntheses,low generality among various proteins,and insufficient serum ***,we developed an enlightened cytosolic protein delivery strategy by dynamically crosslinking epigallocatechin gallate(EGCG),low-molecular-weight polyethylenimine(PEI 1.8k),and 2-acetylphenylboric acid(2-APBA)on the protein surface,hence forming the EPP-protein nanocapsules(NCs).EGCG enhanced protein encapsulation via hydrogen bonding,and reduced the positive charge density of PEI to endow the NCs with high serum tolerance,thereby enabling effective cellular internalization in *** formation of reversible imine and boronate ester among 2-APBA,EGCG,and PEI 1.8k allowed acid-triggered dissociation of EPP-protein NCs in the endolysosomes,which triggered efficient intracellular release of the native *** strategy therefore showed high efficiency and universality for diversities of proteins with different molecular weights and isoelectric points,including enzyme,toxin,antibody,and CRISPR(clustered regularly interspaced short palindromic repeats)-Cas9 ribonucleoprotein(RNP),outperforming the commercial protein transduction reagent PULSin and RNP transfection reagent lipofectamine ***,intravenously(i.v.)injected EPP-saporin NCs efficiently delivered saporin into 4T1 tumor cells to provoke robust antitumor *** simple,versatile,and robust cytosolic protein delivery system holds translational potentials for the development of protein-based therapeutics.

关键词： nanocapsules dynamic crosslinking cytosolic protein delivery serum resistance antitumor therapy genome editing

Effects of dietary zinc deficiency on esophageal squamous cell proliferation and the mechanisms involved

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World Journal of Gastrointestinal Oncology 2021年第11期13卷 1755-1765页

作者： Yao Chen Fang-xun liu Hong liu Department of Traditional Chinese Medicine Peking University International HospitalBeijing 102206China International Medical Center Peking University International HospitalBeijing 102206China Department of Gastroenterology Beijing Shijitan Hospital Affiliated to Capital Medical UniversityBeijing 100038China

BACKGROUND Dietary zinc deficiency has been shown to be associated with the development of esophageal cancer in humans,but the exact mechanism of action is not known AIM To observe the effects of dietary zinc deficiency on esophageal squamous cell *** Thirty C57BL/6 mice were randomly divided into three groups:A zinc-sufficient(ZS)group,zinc-deficient(ZD)group,and zinc-replenished(ZR)*** weeks 1–10,zinc levels in the mice diets were 30.66–30.89 mg/kg in the ZS group and 0.66–0.89 mg/kg in the ZD and ZR *** weeks 10–12,the ZR group was switched to the ZS diet;the other two groups had no changes in their *** in body weight,serum,and esophageal tissue zinc concentrations were assessed as well as differences in the expression of proliferating cell nuclear antigen(PCNA),mitogen-activated protein kinase p38(p38MAPK),nuclear factor kappa B(NF-κB)p105,NF-κB p65,and cyclooxygenase(COX)-2 proteins in the esophageal *** The body weight and zinc concentration in the serum and esophageal mucosa were significantly lower in the ZD and ZR groups than in the ZS group(P<0.05).In ZD mice,there was a marked proliferation of basal cells in the esophageal mucosa,resulting in a disturbance in the arrangement of basal cells in layers 2–4,a thickening of the squamous layer,and a significant increase in the expression of the above-mentioned five proteins involved in proliferation and inflammation in the esophageal *** weeks after switching to the ZS diet,the serum zinc concentration in the ZR group increased,and the expression of PCNA,NF-κB p105,and COX-2 decreased,but the concentration of zinc in the esophageal mucosa and the structure of the esophageal mucosa did not display any significant changes CONCLUSION The ZD diet decreased the growth rate and promoted the proliferation of esophageal squamous cells in *** mechanism of proliferation was related to the induced overexpression of COX-2,P38,PCNA,and NF-κB(p105 and p65),an

关键词： Zinc deficiency Esophageal cancer Esophageal squamous cell carcinoma Esophageal squamous cells Cell proliferation Inflammatory response

Large-scale synthesis of size-controllable Ag nanoparticles by reducing silver halide colloids with different sizes

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Chinese Chemical Letters 2019年第3期30卷 797-800页

作者： Xing Chen xun liu Kai Huang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing Key Lab of Green Recycling and Extraction of Rare and Precious Metals University of Science and Technology Beijing

In present study, double-jet precipitation method was employed to prepare the uniform AgX(X: Cl, Br, I)colloids, and then ascorbic acid/sodium borohydride was respectively used to reduce AgX into the silver nanoparticles(Ag NPs). The main experimental parameters about above two processes were investigated. It was found that under the same synthesis conditions the size of obtained Ag NPS was strongly dependent on the AgX size, and the silver particles obtained by reduction of AgCl, AgBr and AgI had the monotonously diminishing size order. SEM, TEM, XRD, and UV spectrometry were employed to characterize the obtained AgX and Ag NPs respectively, and they gave the size variation clearly and the mechanism was discussed.

关键词： Ag nanoparticles Silver halide Double-jet precipitation Reduction Controllable

Numerical simulation of pedestrian flow past a circular obstruction

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Acta Mechanica Sinica 2011年第2期27卷 215-221页

作者： Yan-Qun Jiang Ru-xun liu Ya-Li Duan Department of Mathematics Southwest University of Science and Technology 621010 Mianyang China Department of Mathematics University of Science and Technology of China 230026 Hefei China

In this paper, a revisiting Hughes’ dynamic continuum model is used to investigate and predict the essential macroscopic characteristics of pedestrian flow, such as flow, density and average speed, in a two dimensional continuous walking facility scattered with a circular obstruction. It is assumed that pedestrians prefer to walk a path with the lowest instantaneous travel cost from origin to destination, under the consideration of the current traffic conditions and the tendency to avoid a high-density region and an obstruction. An algorithm for the pedestrian flow model is based on a cellcentered finite volume method for a scalar conservation law equation, a fast sweeping method for an Eikonal-type equation and a second-order TVD Runge-Kutta method for the time integration on unstructured meshes. Numerical results demonstrate the effectiveness of the algorithm. It is verified that density distribution of pedestrian flow is influenced by the position of the obstruction and the path-choice behavior of pedestrians.

关键词： Pedestrian flow · Continuum model ·Finite volume method · Unstructured meshes · Obstruction

A calibration and compensation method for an industrial robot with high accuracy harmonic reducers

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Science China(Technological Sciences) 2024年第3期67卷 725-739页

作者： ZHAO YiYang liu xun CAO JiaBin liu JinYu XU Yan YAN WeiXin School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Computer and Control Engineering Northeast Forestry UniversityHarbin 150040China

Industrial serial robots need high stiffness to keep absolute pose accuracy and meet the requirements in practical applications. However, the weak stiffness feature of robot joints and the payloads affected on robot end-effector, which will also increase the pose error of robot. Especially, the existing calibration methods often consider under no-payload condition without discussing the payload state. In this paper, we report a new industrial serial robot composed by a new harmonic reducer: Model-Y, based on high accuracy and high stiffness, and a kinematic parameter calibration algorithm which is based on a harmonic reducer forcedeformation model. To decrease the accuracy effects of payload, an iterative calibration method for kinematic parameters with payload situation was proposed. Simulation and experiments are conducted to verify the effectiveness of the proposed calibration method using the self-developed industrial serial robot. The results show a remarkably improved accuracy in absolute position and orientation with the robot's payload range. The position mean error has 70% decreased to 0.1 mm and the orientation mean error diminished to less than 0.01° after calibration with compensation. Additionally, online linear and circular tests are carried out to evaluate the position error of the robot during large-scale spatial and low-speed continuous movement. The accuracy is consistent with the previous calibration results, indicating the effectiveness and advantages of the proposed strategy in this article.

关键词： industrial serial robot Model-Y harmonic calibration stiffness model online compensation