Local and Parallel Finite Element Algorithms for Eigenvalue Problems

Abstract Some new local and parallel finite element algorithms are proposed and analyzed in this paper foreigenvalue problems.With these algorithms, the solution of an eigenvalue problem on a fine grid is reduced tothe solution of an eigenvalue problem on a relatively coarse grid together with solutions of some linear algebraicsystems on fine grid by using some local and parallel procedure.A theoretical tool for analyzing these algorithmsis some local error estimate that is also obtained in this paper for finite element approximations of eigenvectorson general shape-regular grids.     

希土盐与三种α-氨基酸配合物的合成和化学键性质的研究

合成了１４种希土氨基酸的固态配合物，并用反射电子光谱对其进行了表征。根据电子反射光谱数据，对每个配合物的Ｓｌａｔｅｒ－Ｃｏｎｄｏｎ参量（Ｆ２、Ｆ４、Ｆ６）和Ｌａｎｄｅ参量（ζ４５）、Ｎｅｐｈａｌａｎｘｅｔｅ比率（β）进行了计算，还计算了平均共价参数（δ）、成键参数（ｂ１／２）及Ｓｌａｔｅｒ径向积分比值（Ｆ４／Ｆ２与Ｆ６／Ｆ２）。结果表明：在这些配合物中ＲＥ３＋与三种α－氨基酸间配位键存在一定程度的共价性     

Lipid Switches: Stimuli-Responsive Liposomes through Conformational Isomerism Driven by Molecular Recognition

Advancements in the field of liposomal drug carriers have culminated in greatly improved delivery properties. An important aspect of this work entails development of designer liposomes for release of contents triggered by environmental changes. The majority of these systems are driven by chemical reactions in the presence of different stimuli. However, a promising new paradigm instead focuses on molecular recognition events as the impetus for content release. In certain cases, these platforms exploit synthetic lipid switches designed to undergo conformational changes upon binding to target ions or molecules that perturb membrane assembly, thereby triggering cargo release. Examples of this approach reported thus far showcase how rational design of lipid switches can result in dramatic changes in lipid assembly properties. These strategies show great promise for opening up new pathophysiological stimuli that can be harnessed for programmed content release in drug delivery applications.     

基于最小电压法的超声换能器谐振频率自动跟踪*

首先分析了最大电流法跟踪超声换能器谐振频率的原理及应用范围。研究了基于由串联电感和并联电容匹配电路下,不同频率时换能器两端电压电流的变化规律。研究表明在串联电感和并联电容匹配电路下发生谐振时,换能器两端的电压最小而电流并非最大。由此形成了采用最小电压法跟踪谐振频率的自动跟踪策略,并给出了该方法的具体实施步骤。论文研究结果为换能器谐振频率的自动跟踪方法提供了新的选择。     

Local and Parallel Finite Element Algorithms Based on Two-Grid Discretizations for Nonlinear Problems

In this paper, some local and parallel discretizations and adaptive finite element algorithms are proposed and analyzed for nonlinear elliptic boundary value problems in both two and three dimensions. The main technique is to use a standard finite element discretization on a coarse grid to approximate low frequencies and then to apply some linearized discretization on a fine grid to correct the resulted residual (which contains mostly high frequencies) by some local/parallel procedures. The theoretical tools for analyzing these methods are some local a priori and a posteriori error estimates for finite element solutions on general shape-regular grids that are also obtained in this paper.     

Global and uniform convergence of subspace correction methods for some convex optimization problems

This paper gives some global and uniform convergence estimates for a class of subspace correction (based on space decomposition) iterative methods applied to some unconstrained convex optimization problems. Some multigrid and domain decomposition methods are also discussed as special examples for solving some nonlinear elliptic boundary value problems.

     

Cyclic Disulfide Liposomes for Membrane Functionalization and Cellular Delivery

Liposomes are effective therapeutic delivery nanocarriers due to their ability to encapsulate and enhance the pharmacokinetic properties of a wide range of therapeutics. Two primary areas in which improvement is needed for liposomal drug delivery is to enhance the ability to infiltrate cells and to facilitate derivatization of the liposome surface. Herein, we report a liposome platform incorporating a cyclic disulfide lipid (CDL) for the dual purpose of enhancing cell entry and functionalizing the liposome membrane through thiol-disulfide exchange. In order to accomplish this, CDL-1 and CDL-2 , composed of lipoic acid (LA) or asparagusic acid (AA) appended to a lipid scaffold, were designed and synthesized. A fluorescence-based microplate immobilization assay was implemented to show that these compounds enable convenient membrane decoration through reaction with thiol-functionalized small molecules. Additionally, fluorescence microscopy experiments indicated dramatic enhancements in cellular delivery when CDLs were incorporated within liposomes. These results demonstrate that multifunctional CDLs serve as an exciting liposome system for surface decoration and enhanced cellular delivery.     

Preparation and characterization of sulfonated polyimide/TiO2 composite membrane for vanadium redox flow battery

A sulfonated polyimide (SPI)/TiO₂ composite membrane was fabricated by a blend way to improve its performance in vanadium redox flow battery (VRB). Both EDS and XRD results verify the successful preparation of the SPI/TiO₂ composite membrane. The surface SEM image shows its homogeneous structure. TG analysis identifies its thermal stability. The SPI/TiO₂ composite membrane possesses much lower permeability of VO²⁺ ions (2.02?×?10^?7 cm² min^?1) and favorable proton conductivity (3.12?×?10^?2 S cm^?1). The VRB single cell with SPI/TiO₂ composite membrane shows higher coulombic efficiency (93.80–98.00 %) and energy efficiency (83.20–67.61 %) at the current density ranged from 20 to 80 mA cm^?2 compared with that with Nafion 117 membrane. And the operational stability of the as-prepared composite membrane is good after 50 times of cycling tests. Therefore, the low-cost SPI/TiO₂ composite membrane with excellent battery performance exhibits a great potential for application in VRB.