Bipolar doping and band-gap anomalies in delafossite transparent conductive oxides

Doping wide-gap materials p type is highly desirable but often difficult. This makes the recent discovery of p-type delafossite oxides, CuM(III)O2, very attractive. The CuM(III)O2 also show unique and unexplained physical properties: Increasing band gap from M(III) = Al,Ga, to In, not seen in conventional semiconductors. The largest gap CuInO2 can be mysteriously doped both n and p type but not the smaller gaps CuAlO2 and CuGaO2. Here, we show that both properties are results of a large disparity between the fundamental gap and the apparent optical gap, a finding that could lead to a breakthrough in the study of bipolarly dopable wide-gap semiconductor oxides.     

Optimal control for elliptic systems with pointwise euclidean norm constraints on the controls

Optimal control for an elliptic system with pointwise Euclidean norm constraints on the control variables is investigated. First order optimality conditions are derived in a manner that is amenable for numerical realisation. An efficient semismooth Newton algorithm is proposed based on this optimality system. Numerical examples are given to validate the superlinear convergence of the semismooth Newton algorithm.     

Electrochemical preparation of distinct polyaniline nanostructures by surface charge control of polystyrene nanoparticle templates

A family of nanostructured polyaniline (PANI) materials including polystyrene (PS)/PANI core/shell particles, PANI hollow spheres, PANI/PS nanocomposite and nanoporous PANI, were conveniently prepared by surface charge control of PS nanoparticle templates which resulted in different polymer growth mechanisms when PANI was electropolymerized around the templates.     

Ultrasensitive protein detection using an aptamer-functionalized single polyaniline nanowire

A highly sensitive, conductometric and label-free biosensor for the detection of immunoglobulin E (IgE) is developed based on the immobilzation of the IgE aptamer onto a single polyaniline nanowire electrochemically synthesized in a facile and controllable way.     

Optimal control for multi-phase fluid Stokes problems

Optimal control for a system consistent of the viscosity dependent Stokes equations coupled with a transport equation for the viscosity is studied. Motivated by a lack of sufficient regularity of the adjoint equations, artificial diffusion is introduced to the transport equation. The asymptotic behavior of the regularized system is investigated. Optimality conditions for the regularized optimal control problems are obtained and again the asymptotic behavior is analyzed. The lack of uniqueness of solutions to the underlying system is another source of difficulties for the problem under investigation.     

酶凝干酪素物理凝胶化过程的有限元模拟

以酶凝干酪素的凝胶化过程为对象,利用有限元方法数值分析了在凝胶化过程中温度场的空间分布和时间演变规律.在此基础上,基于一阶的凝胶化动力学方程,数值模拟了凝胶体系的复剪切模量场,进而分析了材料配方、体系尺寸与冷却方案对复剪切模量场的影响规律.模拟结果表明,由于热阻的差异,体系表面的冷却速率大于内部,表面首先发生凝胶化;而由于预凝胶化阶段的平均冷却速率决定了无穷复剪切模量的值,最终体系内部的复剪切模量超过表面的.     

A sensitive chemiluminescence method for the determination of cysteine based on silver nanoclusters

We have developed a sensitive chemiluminescent (CL) assay for cysteine. It is based on the use of water-soluble and fluorescent silver nanoclusters (Ag NCs) which are found to be able to strongly enhance the weak CL signal resulting from the redox reaction between Ce(IV) ion and sulfite ion. This enhancement is inhibited by cysteine under appropriate conditions. Taking advantage of this specific CL inhibition, a novel CL method for the sensitive and selective detection of cysteine was developed. This effect is interpreted in terms of an electronic energy transfer from excited state intermediate sulfur dioxide (originating from the CL reaction between Ce(IV) and sulfite ions) to the Ag-NCs. The latter become electronically excited and thus can act as a new source of emission. The method was applied to the determination of cysteine in the range from 5.0?nM to 1.0?μM, with a detection limit at 2.5?nM (S/N?=?3).

Electrochemically controlled release based on nanoporous conducting polymers

An electrochemically controlled drug release system based on nanoporous polypyrrole (PPy) films was developed. Pyrrole and a model drug, fluorescein, were electrochemically copolymerized on glassy carbon (GC) electrodes modified with self-assembled multilayer polystyrene (PS) nanobeads, and PPy films incorporated with fluorescein as dopants were formed among the interstitial spaces of the tightly packed PS nanobead template. After the removal of the PS hard template, nanoporous PPy films incorporated with the drug fluorescein were obtained. Due to the porous morphology and huge surface area, the efficiency of the prepared PPy films in electrochemically releasing incorporated fluorescein was about nine times higher than that of conventional PPy films.     

Reversible resistance switching properties in Ti-doped polycrystalline Ta2O5 thin films

Unipolar reversible resistance switching effects were found in 5 at% Ti-doped polycrystalline Ta₂O₅ films with the device structure of Pt/Ti–Ta₂O₅/Pt. Results suggest that the recovery/rupture of the conductive filaments which are involved in the participation of oxygen vacancies and electrons leads to the resistance switching process. Ti-doped Ta₂O₅ thin films possess higher resistance whether in low-resistance state or high-resistance state and higher resistance switching ratio than Ta₂O₅ thin films, where Ti addition plays an important role in the resistance switching process by suppressing the migration of oxygen vacancies via forming an electrically inactive Ti/O–vacancy complex. Excellent retention properties of the high and low resistances under constant stress of applied voltage were obtained.