Finite cell method compared to h-version finite element method for elasto-plastic problems

The finite cell method （FCM） combines the high-order finite element method （FEM） with the fictitious domain approach for the purpose of simple meshing. In the present study, the FCM is used to the Prandtl-Reuss flow theory of plasticity, and the results are compared with the h-version finite element method （h-FEM）. The numerical results show that the FCM is more efficient compared to the h-FEM for elasto-plastic problems, although the mesh does not conform to the boundary. It is also demonstrated that the FCM performs well for elasto-plastic loading and unloading.

Shape optimization of axisymmetric solids with the finite cell method using a fixed grid

In this work, a design procedure extending the B-spline based finite cell method into shape optimization is developed for axisymmetric solids involving the centrifugal force effect. We first replace the traditional conforming mesh in the finite element method with structured cells that are fixed during the whole design process with a view to avoid the sophisticated re-meshing and eventual mesh distortion.Then, B-spline shape functions are further implemented to yield a high-order continuity field along the cell boundary in stress analysis. By means of the implicit description of the shape boundary, stress sensitivity is analytically derived with respect to shape design variables. Finally, we illustrate the efficiency and accuracy of the proposed protocol by several numerical test cases as well as a whole design procedure carried out on an aeronautic turbine disk.

A porous cell method for the simulation of fluid-solid interactions

There are many ways of describing a solid,porous or fluid region of the computational domain when solving the Navier-Stokes equations(NSE)for flow motions.Amongst these the porous cell method is one of the most flexible approaches.In this method,a parameter is defined as a ratio of the volume open to water and air in a calculation cell to its cell volume.In the calculation,the same numerical procedure is applied to every cell and no explicit boundary conditions are needed at solid boundaries.The method is used to simulate flow through porous media,around solid bodies and over a moving seabed.The results compare well with experimental data and other numerical results.In our future work the porous cell method will be applied to more complex fluid-solid interaction situations.

Direct Numerical Simulation of a Jet Issuing from Rectangular Nozzle by the Vortex in Cell Method

Direct numerical simulation of a jet issuing from a nozzle having a rectangular cross-section is conducted. The vortex in cell (VIC) method, of which computational accuracy was heightened by the authors in a prior study, is used for the DNS. The aspect ratio of the nozzle cross-section is 15, and the Reynolds number based on the shorter side length of the nozzle exit is 6700. The turbulence statics, such as the mean velocity and the turbulence intensity, are favorably compared with the experimentally measured results. The behavior of the large-scale eddies as well as the development of the turbulent flow is also confirmed to agree with the measurement. These indicate that the authors’ VIC method is successfully employed for the DNS of rectangular jet.

TAILORED FINITE CELL METHOD FOR SOLVING HELMHOLTZ EQUATION IN LAYERED HETEROGENEOUS MEDIUM

In this paper, we propose a tailored finite cell method for the computation of two- dimensional Helmholtz equation in layered heterogeneous medium. The idea underlying the method is to construct a numerical scheme based on a local approximation of the solution to Helmholtz equation. This provides a computational tool of achieving high accuracy with coarse mesh even for large wave number （high frequency）. The stability analysis and error estimates of this method are also proved. We present several numerical results to show its efficiency and accuracy.

A radial basis function for reconstructing complex immersed boundaries in ghost cell method

It is important to track and reconstruct the complex immersed boundaries for simulating fluid structure interaction problems in an immersed boundary method（IBM）. In this paper, a polynomial radial basis function（PRBF） method is introduced to the ghost cell immersed boundary method for tracking and reconstructing the complex moving boundaries. The body surfaces are fitted with a finite set of sampling points by the PRBF, which is flexible and accurate. The complex or multiple boundaries could be easily represented. A simple treatment is used for identifying the position information about the interfaces on the background grid. Our solver and interface reconstruction method are validated by the case of a cylinder oscillating in the fluid. The accuracy of the present PRBF method is comparable to the analytic function method. In ta flow around an airfoil, the capacity of the proposed method for complex geometries is well demonstrated.

The Ghost Cell Method and its Applications for Inviscid Compressible Flow on Adaptive Tree Cartesian Grids

In this paper,an immersed boundary algorithm is developed by combining the ghost cell method with adaptive tree Cartesian grid method.Furthermore,the proposed method is successfully used to evaluate various inviscid compressible flow with immersed boundary.The extension to three dimensional cases is also achieved.Numerical examples demonstrate the proposed method is effective.

Modeling One Dimensional Two-Cell Model with Tumor Interaction Using Krylov Subspace Methods

A brain tumor occurs when abnormal cells grow, sometimes very rapidly, into an abnormal mass of tissue. The tumor can infect normal tissue, so there is an interaction between healthy and infected cell. The aim of this paper is to propose some efficient and accurate numerical methods for the computational solution of one-dimensional continuous basic models for the growth and control of brain tumors. After computing the analytical solution, we construct approximations of the solution to the problem using a standard second order finite difference method for space discretization and the Crank-Nicolson method for time discretization. Then, we investigate the convergence behavior of Conjugate gradient and generalized minimum residual as Krylov subspace methods to solve the tridiagonal toeplitz matrix system derived.

Synthesis and characterization of high density and high aspect ratio Ag_2S nanoparticle nanowires from a paired cell method

Ag_2S nanoparticle nanowires were prepared in a porous anodic aluminum oxide template by a simple paired cell method,and were characterized by XRD,FESEM,HRTEM and EDS.The results showed that the as-prepared nanowires were composed of monoclinic Ag_2S nanoparticles.The nanowire diameters ranged from 165 to 270 nm,and Ag_2S nanoparticles were nearly spherical with diameters of 40 to 60 nm.The paired cell method is simple,low cost and easy to control for the fabrication of high density and high aspect ratio Ag_2S nanoparticle nanowires.A formation mechanism for the nanoparticle nanowires was suggested.

Research method of psoriasis based on HaCaT cells

Psoriasis is a chronic,refractory,inflammatory skin disease that occurs in young adults.The traditional animal model cannot simulate the skin characteristics of patients with psoriasis effectively,so it is difficult to be used for in-depth study of psoriasis mechanism.Immortalized human epidermal cells(HaCaT) is a non-tumor,immortalized human epidermal cell which is widely used in the study of dermatosis.HaCaT cells are the best choice for the study of psoriasis mechanism because their immu.nological characteristics and reproductive ability are coincide with the pathological features of psoriasis.This article reviews the specific methods such as establishment of cell method,cytokine and chemo.kine analysisin the pathogenesis study of psoriasis based on HaCaT cells,hoping to provide some thoughts for drug′s pharmacological activity research.

ONE-CELL-STATE METHOD FOR DETERMINATION OF ELECTRONIC STRUCTURE OF INTERMETALLIC COMPOUNDS

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Generation of Transgene-free Induced Pluripotent Stem Cells with Non-viral Methods

Induced pluripotent stem(iPS) cells were originally generated from mouse fibroblasts by enforced expression of Yamanaka factors(Oct3/4,Sox2,Klf4,and c-Myc).The technique was quickly reproduced with human fibroblasts or mesenchymal stem cells.Although having been showed therapeutic potential in animal models of sickle cell anemia and Parkinson's disease,iPS cells generated by viral methods do not suit all the clinical applications.Various non-viral methods have appeared in recent years for application of iPS cells in cell transplantation therapy.These methods mainly include DNA vector-based approaches,transfection of mRNA,and transduction of reprogramming proteins.This review summarized these non-viral methods and compare the advantages,disadvantages,efficiency,and safety of these methods.

Establishment and validation of a method for cell irradiation in 96-well and 6-well plates using a linear accelerator

To establish and validate a method for cell irradiation in 96-well and 6-well plates using a linear accelerator, three irradiation methods(G0 B0 F40,G0 B1.5 F40, and G180 B1.5 F40) were designed to irradiate cell culture plasticware simulated with RW3 slab phantom and polystyrene. The difference between the actual physical measured dose and the preset dose was compared among the three methods under the preparatory conditions of 2, 4, 6, 8, and 10 Gy. MDA-MB-231 cells were analyzed by using a cell proliferation assay and a clonogenic assay to verify the difference between the three cell irradiation methods on cell radiosensitivity. For each preset dose, the difference between the actual measured dose and the preset dose was the lowest for Method G0 B1.5 F40, the second lowest for Method G180 B1.5 F40, and the maximum for Method GOB0 F40. The ranges of the differences were-0.28 to 0.02%,-2.17 to-1.80%, and-4.92 to-4.55%, and 0.31 to-0.12%,-3.42 to-2.86%, and-7.31 to-6.92%,respectively, for 96-well and 6-well plates. The cell culture experiments proved that Method G0 B1.5 F40 was an accurate, effective, simple, and practical irradiation method. The most accurate and effective cell irradiation method should always be used, as it will reduce dose differences and instability factors and provide improved accuracy and comparability for laboratories researching cellular radiosensitivity.

Stochastic response analysis of noisy system with non-negative real-power restoring force by generalized cell mapping method

The stochastic response of a noisy system with non-negative restoring force is investigated. The generalized cell mapping （GCM） method compute the transient and stationary probability density functions （PDFs） real-power is used to Combined with the global properties of the noise-free system, the evolutionary process of the tran- sient PDFs is revealed. The results show that stochastic P-bifurcation occurs when the system parameter varies in the response analysis and the stationary PDF evolves from bimodal to unimodal along the unstable manifold during the bifurcation.

Preparation of Se-based solar cell using spin-coating method in ambient condition

A new hybrid organic-inorganic structure of FTO/TiO2/Se/HTL/Au based selenium solar cell has been fabricated through a low-cost spin-coating process in air. In this process, selenium is completely dissolved in hydrazine, to fk）rm a homogeneous precursor solution. After spin-coating the precursor solution on the TiO2 substrates, following by sintering at 200 ℃ for 5rain, a uniform selenium film with crystalline grains is formed. The selenium based solar cell exhibits an efficiency of 1.23% under AM1.5 illumination （100 mW.cm-2）, short-circuit current density of 8 mA.cm 2, open-circuit voltage of 0.55 V, and fill factor of 0.37. Moreover, the device shows a stable ability with almost the same performance alter 60 days.

Spherical silicon solar cell with reflector cup fabricated by decompression dropping method

A spherical Si solar cell with a reflector cup was successfully fabricated by a dropping method at decompression state. In the dropping method, melted Si droplets were instilled at decompression state (0.5×105 Pa) to reduce crystal growth rate, dominating crystal quality such as dislocation density in crystal grains. Spherical Si solar cells were fabricated using the spherical Si crystals with a diameter of 1 mm and then mounted on a reflector cup. The current-voltage measurement of the solar cell shows an energy conversion efficiency of 11.1% (short-circuit current density (Jsc): 24.7 mA·cm-2, open-circuit voltage: 601 mV, fill factor: 74.6%). Minority carrier diffusion length determined by surface photovoltage method was 98 μm. This value can be enhanced by the improvement of crystal quality of spherical Si crystals. These results demonstrate that spherical Si crystals fabricated by the dropping method has a great potential for substrate material of high-efficiency and low-cost solar cells.

Study of a Quantitative Fluorescence Method for Interleukin 2 Receptor of Mononuclear Cell in Normal Human Peripheral Blood

A quantitative method using fluorescence spectro-photometer to detect theinterleukin 2 reocptor （IL 2R） on the surface of mononuclear cells in normal humanperipheral blood is described. For expression of IL 2R, the optimum conoentration of PHA andCon A were 100 μg/ml and 10 μg/ml respectively. The PHA induced effect on mononuclear cellswas better than Con A induced one. The peak value of IL 2R cxpression was at the 24th h afterstimulation The optimum dilution of the first antibody （anti-Tac） was 1: 50, while the dilution ofthe second antibody（fluorescein conjugated rabbit anti-mousc IgG） was 1: 32 Their optimumincubation period was 20 and 10 min repectively. The concentration of fluorcscein-conjugatedantibody per 1×106 mononuclear cells from the same normal human peripheral blood was5.22±0.45×10-10 mol, and the coefficient of variation was 8. 6%. The concentration offluorescein-conjugated antibody per 1×106PBMC from five healthy individuals was 4. 8±0. 97×10-10 mol Therefore this assay system is stable and quite reproducible.

A NEW METHOD OF ISOLATING KUPFFER CELLS FROM BIOPSY TISSUE OF RAT LIVER

The isolation of a high yield and purity of Kupffer cells has been reported in detail.1 This paper reports into the research about isolation Kupffer cells from biopsy tissue of liver. This method includes 5 important steps: (1) take fresh liver tissue, and mince with scissors. (2) spin at low speed to wash off red blood cells. (3) digest in collagenase for suitable time. (4) isolate Kupffer cells on a percoll density gradient. (5) cell charaterization was observed by N.S.E stain and peroxidatic activity with lumino-meter measurement and phagocytosis with latex beads.2.3