5,804 research outputs found
Two and Three-Dimensional Models for Material and Cells Interaction
Three-dimensional (3D) cell spheroid model has been long considered a better model to mimic in vivo physiology compared to two-dimensional (2D) cell culture model. Traditional 2D cell models provide a simple, convenient and quick technique for drug screening but fail to simulate the complexity and heterogeneity of cells in the in vivo environment. The last few decades have remarked substantial progress toward the advancement of three-dimensional (3D) cell cultures as systems which better mimic cellcell and cell-matrix interaction in the in vivo physiology. Nowadays, 3D cell models have been emerging, not only as an important approach in drug discovery and tissue engineering but also as potential therapeutics assessment for the development of new anticancer strategies. The employment of new 3D cell culture models in combination with traditional 2D models and co-culture models of two or more cell types would enable more accurate evaluation of drug efficiency and sensitivity, toxicity, resistance for in vitro testings before moving into in vivo studies and clinical trials.
A novel material, copper high aspect ratio structure (CuHARS) which is biocompatible, biodegradable and less toxic compared to copper nanoparticles with the same amount of copper has the potential to be used as a delivery system for drug treatment or tissue engineering. Moreover, a combination of CuHARS and disulfiram (DSF) to form DSF metal complex showed significant increase in growth inhibition of gliomas in both 2D and 3D models suggested a promising approach in treating glioblastomas
Securing Downlink Massive MIMO-NOMA Networks with Artificial Noise
In this paper, we focus on securing the confidential information of massive
multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA)
networks by exploiting artificial noise (AN). An uplink training scheme is
first proposed with minimum mean squared error estimation at the base station.
Based on the estimated channel state information, the base station precodes the
confidential information and injects the AN. Following this, the ergodic
secrecy rate is derived for downlink transmission. An asymptotic secrecy
performance analysis is also carried out for a large number of transmit
antennas and high transmit power at the base station, respectively, to
highlight the effects of key parameters on the secrecy performance of the
considered system. Based on the derived ergodic secrecy rate, we propose the
joint power allocation of the uplink training phase and downlink transmission
phase to maximize the sum secrecy rates of the system. Besides, from the
perspective of security, another optimization algorithm is proposed to maximize
the energy efficiency. The results show that the combination of massive MIMO
technique and AN greatly benefits NOMA networks in term of the secrecy
performance. In addition, the effects of the uplink training phase and
clustering process on the secrecy performance are revealed. Besides, the
proposed optimization algorithms are compared with other baseline algorithms
through simulations, and their superiority is validated. Finally, it is shown
that the proposed system outperforms the conventional massive MIMO orthogonal
multiple access in terms of the secrecy performance
Geometrically nonlinear polygonal finite element analysis of functionally graded porous plates
In this study, an efficient polygonal finite element method (PFEM) in combination with quadratic serendipity shape functions is proposed to study nonlinear static and dynamic responses of functionally graded (FG) plates with porosities. Two different porosity types including even and uneven distributions through the plate thickness are considered. The quadratic serendipity shape functions over arbitrary polygonal elements including triangular and quadrilateral ones, which are constructed based on a pairwise product of linear shape functions, are employed to interpolate the bending strains. Meanwhile, the shear strains are defined according to the Wachspress coordinates. By using the Timoshenko's beam to interpolate the assumption of the strain field along the edges of polygonal element, the shear locking phenomenon can be naturally eliminated. Furthermore, the C0–type higher-order shear deformation theory (C0–HSDT), in which two additional variables are included in the displacement field, significantly improves the accuracy of numerical results. The nonlinear equations of static and dynamic problems are solved by Newton–Raphson iterative procedure and by Newmark's integration scheme in association with the Picard methods, respectively. Through various numerical examples in which complex geometries and different boundary conditions are involved, the proposed approach yields more stable and accurate results than those generated using other existing approaches
Multi-group linear turbo equalization with intercell interference cancellation for MC-CDMA cellular systems.
In this paper, we investigate multi-group linear turbo equalization using single antenna interference cancellation (SAIC) techniques to mitigate the intercell interference for multi-carrier code division multiple access (MC-CDMA) cellular systems. It is important for the mobile station to mitigate the intercell interference as the performance of the users close to cell edge is mainly degraded by the intercell interference. The complexity of the proposed iterative detector and receiver is low as the one-tap minimum mean square error (MMSE) equalizer is employed for mitigating the intracell interference, while a simple group interference canceller is used for suppressing the intercell interference. Simulation results show that the proposed iterative detector and receiver can mitigate the intercell interference effectively through iterations for both uncoded and coded signals
Analysis and control of geometrically nonlinear responses of piezoelectric FG porous plates with graphene platelets reinforcement using B\'ezier extraction
In this study, we propose an effective numerical approach to analyse and
control geometrically nonlinear responses for the functionally graded (FG)
porous plates reinforced by graphene platelets (GPLs) integrated with
piezoelectric layers. The basis idea is to use isogeometric analysis (IGA)
based on the B\'ezier extraction and the -type higher-order shear
deformation theory (-HSDT). By applying the B\'ezier extraction, the
original Non-Uniform Rational B-Spline (NURBS) control meshes can be
transformed into the B\'ezier elements which allow us to inherit the standard
numerical procedure like the finite element method (FEM). The mechanical
displacement field is approximated based on the -HSDT whilst the electric
potential is assumed to be a linear function through the thickness of each
piezoelectric sublayer. The FG plate contains the internal pores and GPLs
dispersed in the metal matrix either uniformly or non-uniformly according to
various different patterns along the thickness of plate. In addition, to
control dynamic responses, two piezoelectric layers are perfectly bonded on the
top and bottom surfaces of the FG plate. The geometrically nonlinear equations
are solved by the Newton-Raphson iterative procedure and the Newmark's time
integration scheme. The influences of the porosity coefficients, weight
fractions of GPLs as well as the external electrical voltage on the
geometrically nonlinear behaviours of the plates with different porosity
distributions and GPL dispersion patterns are evidently investigated through
numerical examples. Then, a constant displacement and velocity feedback control
approaches are adopted to active control the geometrically nonlinear static as
well as the dynamic responses of the FG porous plates, where the effect of the
structural damping is considered, based on a closed-loop control with
piezoelectric sensors and actuators.Comment: 39 pages, 20 figure
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