Limitations of the Clausius‐Mossotti function used in dielectrophoresis and electrical impedance studies of biomacromolecules

Dielectrophoresis (DEP) studies have progressed from the microscopic scale of cells and bacteria, through the mesoscale of virions to the molecular scale of DNA and proteins. The Clausius‐Mossotti function, based on macroscopic electrostatics, is invariably employed in the analyses of all these studies. The limitations of this practice are explored, with the conclusion that it should be abandoned for the DEP study of proteins and modified for native DNA. For macromolecular samples in general, a DEP theory that incorporates molecular‐scale interactions and the influence of permanent dipoles is more appropriate. Experimental ways to test these conclusions are proposed.     

Noble metal nanoparticles meet molecular cages: A tale of integration and synergy

Noble metal nanoparticles attract growing interest owing to their high surface-to-volume ratio and unique optical, electric and catalytic properties. Fine-tuning these properties and broadening potential applications can be envisaged if nanoparticles are coupled to supramolecular cages that afford a highly tailorable inner environment as well as rich endo-/exo-functionalization. Due to rich chemical/physical properties of cages, integration of multiple host-guest interactions in confined cavities through endo-molecular design has been achieved. Such cages provide ideal confined templates for size-controlled synthesis of ultrafine nanoparticles with superior catalytic activities. Moreover, exo-functionalization of cages offers huge opportunities to couple with nanoparticles, generating cage-nanoparticle hybrids or hierarchical assemblies that combine merits of both. The present review provides recent advances in cage-mediated nanoparticle systems with synergistic effects and integrated functions, and demonstrates their applications in catalysis, sensing, chiral amplification, plasmonic switches, imaging and cell therapy. Finally, we highlight key challenges and identify emerging directions in the coming years.     

The simultaneous elimination of arsenic and mercury ions via hollow fiber supported liquid membrane and their reaction mechanisms: Experimental and modeling based on DFT and generating function

This study investigates the simultaneous removal of low concentrations of arsenic and mercury ions from synthetic produced water via hollow fiber supported liquid membrane (HFSLM). Results show that HFSLM can remove both arsenic and mercury ions from synthetic produced water to less than 0.02 and 0.001 mg·L^-1, respectively. These final concentrations comply with the wastewater standard of Thailand. Percentages of extraction for arsenic and mercury ions proved to be about 100 %. Those of recovery for arsenic and mercury ions reached 70 % and 75 %, respectively. A quantum model based on density functional theory (DFT) is introduced to analyze the forming and breaking of supramolecular complex species in the processes of extraction and recovery, respectively. Furthermore, the concept of Generating Function is applied to construct a mathematical model for forecasting the potential of removing metal ions via HFSLM. The mathematical model conforms to the experimental data, having an average relative deviation of 5 %. The results of this study provide a better understanding of the transport mechanisms of arsenic and mercury ions.     

弹性力学问题的虚边界元-配点法

本文提出虚边界方法,建立了离散化虚边界元-配点法,给出了离散化求系数的积分解析式。本文方法完全避免了边界奇异积分及其复杂耗时的运算,成功地提高了普通边界元法(以下简称边界元法)中边界附近区域内包括边界上解的精度,保留了边界元法的优点并扬弃了其弱点。边界元间接法是本文方法中的一个特例。数值算例表明,程序可靠,节省机时,计算精度较高。     

A novel graphene nanoribbon field effect transistor with two different gate insulators

In this paper, a novel structure for a dual-gated graphene nanoribbon field-effect transistor (GNRFET) is offered, which combines the advantages of high and low dielectric constants. In the proposed Two Different Insulators GNRFET (TDI-GNRFET), the gate dielectric at the drain side is a material with low dielectric constant to form smaller capacitances, while in the source side, there is a material with high dielectric constant to improve On-current and reduce the leakage current. Simulations are performed based on self-consistent solutions of the Poisson equation coupled with Non-Equilibrium Green's Function (NEGF) formalism in the ballistic regime. We assume a tight-binding Hamiltonian in the mode space representation. The results demonstrate that TDI-GNRFET has lower Off-current, higher On-current and higher transconductance in comparison with conventional low-K GNRFET. Furthermore, using a top-of-the-barrier two-dimensional circuit model, some important circuit parameters are studied. It is found that TDI-GNRFET has smaller capacitances, lower intrinsic delay time and shorter power delay product (PDP) in comparison with high-K GNRFET. Moreover, mobile charge and average velocity are improved in comparison with low dielectric constant GNRFET. The results show that the TDI-GNRFET can provide Drain Induced Barrier Lowering (DIBL) and Subthreshold Swing near their theoretical limits.