Synthesis of asymmetric biphenyl derivatives for optoelectronic applications

We report the synthesis and optical properties of a series of ten organic compounds with biphenyl as the backbone and asymmetrically modified by triphenylamines, carbazoles and tetraphenylsilanes (BP 1-10). BP 1-10 were synthesized mainly by Ullmann coupling reaction and Suzuki cross-coupling reaction and characterized by EA, NMR, MS, UV–Vis, DSC, TGA, fluorescence spectra and cyclic voltammetry. They exhibit reversible electrochemical behavior with low oxidation potentials and emit intense pure-blue light with high fluorescence quantum yields (up to 80%). BP 1 was fabricated into multi-layered light-emitting diodes as blue-emitting, host and hole transport materials. Based on the performance of BP 1 and the similarity in chemical structure to those compounds reported in literature, these compounds are expected to be good and versatile hole transport, host and blue emitting materials.     

Multi-objective Topology Optimization of Thermo-mechanical Compliant Mechanisms

The material characteristics of a structure will change with temperature variation,and will induce stress within the structure.Currently,the optimal design for the topology of compliant mechanisms is mainly performed in single physical field.However,when compliant mechanisms work in high temperature environments,their displacement outputs are generated not only by mechanical load,but also by the temperature variation which may become the prominent factor.Therefore,the influence of temperature must be considered in the design.In this paper,a novel optimization method for multi-objective topology of thermo-mechanical compliant mechanisms is presented.First,the thermal field is analyzed with finite-element method,where the thermal strain is taken into account in the constitutive relation,and the equivalent nodal thermal load is derived with the principle of virtual work.Then the thermal load is converted into physical loads in elastic field,and the control equation of the thermo-mechanical compliant mechanism is obtained.Second,the mathematical model of the multi-objective topology optimization is built by incorporating both the flexibility and stiffness.Meanwhile,the coupling sensitivity function and the sensitivity analysis equations of thermal steady-state response are derived.Finally,optimality criteria algorithm is employed to obtain numerical solution of the multi-objective topology optimization.Numerical examples show that the compliant mechanisms have better performance and are more applicable if the temperature effect is taken into account in the design process.The presented modeling and analysis methods provide a new idea and an effective approach to topology optimization of compliant mechanisms in electrothermic coupling field and multiphysics fields.     

Preliminary studies on the use of modified ALCELL lignin as a coupling agent in the biofiber composites

ALCELL lignin has been employed as a coupling agent in empty fruit bunch fiber (EFBF)–polypropylene (PP) composites. The lignin has been chemically modified with toluene diisocyanate (TDI) to various weight loadings. The evidence of the reaction between TDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on mechanical properties has been studied. The results show that the TDI‐modified lignin is able to impart greater compatibility between EFBF and PP. This is reflected in the greater mechanical properties shown by the composites with TDI‐modified lignin than in those with the unmodified lignin. Scanning electron microscopy (SEM) studies showed that TDI modification of lignin resulted in a better blending and compatibility between lignin and PP matrix. The glass‐transition temperature of the lignin increases as the WPG is increased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1333–1340, 2001     

Viewpoint and the recognition of people from their movements.

Observers can recognize other people from their movements. What is interesting is that observers are best able to recognize their own movements. Enhanced visual sensitivity to self-generated movement may reflect the contribution of motor planning processes to the visual analysis of human action. An alternative view is that enhanced visual sensitivity to self-motion results from extensive experience seeing one's own limbs move. To investigate this alternative explanation, participants viewed point-light actors from first-person egocentric and third-person allocentric viewpoints. Although observers routinely see their own actions from the first-person view, participants were unable to identify egocentric views of their own actions. Conversely, with little real-world experience seeing themselves from third-person views, participants readily identified their own actions from allocentric views. When viewing allocentric displays, participants accurately identified both front and rear views of their own actions. Because people have little experience observing themselves from behind or from third-person views, these findings suggest that visual learning cannot account for enhanced visual sensitivity to self-generated action. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Numerical research for contaminant release from un-suspended bottom sediment under different hydrodynamic conditions

Contaminant release from bottom sediments in rivers is one of the main problems to study the environmental hydrodynamics. Contaminant will release into the overlying water column under different hydrodynamic conditions through pore-water in sediment, the release mechanism can be roughly divided into convection diffusion, molecular diffusion and adsorption/desorption. In this article, phosphorus was as a typical contaminant with sorption. Through theoretical analysis of the contaminant release, according to different particle-sized and hydraulic conditions, the mathematics model of contaminant release can be established by the coupled Navier-Stokes equation, Darcy equation, solute transport equation and adsorption/desorption equation. Then that model was verified by flume experiment. Numerical studies show that, under different velocity, the instantaneous concentration of convection diffusion is about 6 times to 50 times larger than that of molecular diffusion during initial stages. The concentration of molecular diffusion is about 1 times to 4 times larger than to that of convection diffusion during late stages. Through analysis, the diffusive boundary layer near the interface can be obtained. In addition, the release will increase with particle size decreasing, and the release will be influenced much more by the size change when the particle size is relatively big under different velocity.     

Dynamics of a Dual Power-split Transmission Based on Loaded Tooth Contact Analysis

In order to implement the dynamic characteristic of a dual power-split transmission,a dynamic mechanics model is built. Firstly,according to the method of theoretical analysis of the tooth contact analysis ( TCA) and loaded tooth contact analysis ( LTCA) ,the actual meshing process of each gear pairs is simulated, and the time-varying mesh stiffness excitations are obtained,which can improve the numerical precision. Secondly,by using the lumped mass method,the bending-torsional coupling three dimensional dynamic model of the dual power-split transmission is established,and the identical dimensionless equations are deduced by eliminating the effect of rigid displacement and the method of dimensional normalization. Finally,by the method of the fourth order Runge-Kutta algorithm with variable step lengths,the responses of this system in a frequency domain and time domain are obtained,and the dynamic load change characteristics of each gear pairs are analyzed. The results show that the establishment,solution and analysis of the system dynamics model could provide a basis for the dynamic design,and have an important significance for the dynamic efficiency analysis and dynamic performance optimization design of the dual power-split transmission.     

基于MC2833和MC3362的RFID系统设计

RFID系统主要由阅读器和应答器组成。阅读器包含高频接收模块、控制单元及与应答器连接的耦合元件。高频接收模块以单片集成接收芯片MC3362为核心,结合MC145151构成锁相回路,接收应答器发送的信息。应答器由耦合元件以及高频发射模块组成,其工作所需能量全部由耦合线圈提供,采用自动开关控制应答器与电源的通断以降低功耗。     

多场耦合下微波碳热氯化回收铟的动态仿真

以实验室微波反应器为研究对象,基于有限元软件COMSOL Multiphysics,采用多场耦合方法对微波强化碳热氯化回收In Cl3的反应过程进行了动态仿真,并分析了其影响因素。结合微波加热过程、计算流体力学和物质传输过程,建立了由射频、传热、传质和流场4个物理场耦合的数学物理模型。通过考察腔室内的电场强度,得到微波加热过程的热源项与样品体的温度分布。结果表明,本研究模型能够准确描述微波输入功率、HCl通入浓度等多因素对铟化物回收过程的影响,为微波碳热氯化提铟过程的分析提供新的方法与依据。     

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

Minor Role of Mitochondrial Respiration for Fatty-Acid Induced Insulin Secretion

An appropriate insulin secretion by pancreatic beta-cells is necessary to maintain glucose homeostasis. A rise in plasma glucose leads to increased metabolism and an elevated cytoplasmic ATP/ADP ratio that finally triggers insulin granule exocytosis. In addition to this triggering pathway, one or more amplifying pathways—activated by amino acids or fatty acid—enhance secretion by promoting insulin granule recruitment to, and priming at, the plasma membrane. The aim of this study was to clarify the impact of the mitochondrial respiratory activity on fatty acid-induced insulin secretion that was assessed by an extracellular flux analyzer. Treatment of isolated mouse islets with glucose (20 mM) increased insulin secretion 18-fold and correlated with ATP-synthesizing respiration. Furthermore, oxygen consumption rate (OCR) significantly increased by 62% in response to glucose, whereas the addition of palmitate resulted only in a minor increase of OCR at both 2.8 mM (11%) and 20 mM glucose (21%). The addition of palmitate showed a pronounced increase of coupling efficiency (CE) at 2.8 mM glucose but no further insulin secretion. However, treatment with palmitate at 20 mM glucose increased insulin secretion about 32-fold accompanied by a small increase in CE. Thus, fatty acid induced respiration has a minor impact on insulin secretion. Our data clearly demonstrate that fatty acids in contrast to glucose play a minor role for respiration-mediated insulin secretion. In the presence of high glucose, fatty acids contribute partially to amplifying pathways of insulin secretion by further increasing mitochondrial activity in the islets of Langerhans.