神经元电突触前向传输电导的时变特性

电突触前膜在高于阈值的刺激下,产生一个大小不变的动作电位,突触后细胞可直接被突触前轴突中伴随动作电位产生的电紧张所激活,突触膜相当于整流器,电流只能从突触前神经元流向突触后神经元。电流流过神经元之间结合部时,连结电导将随时间变化。

高频OTA-C梯形结构低通滤波器的设计

给出一种基于线性变换技术及网络传输方程设计的高频运算传输电导放大器—电容(OTA_C)的梯形结构低通滤波器的方法 ,归纳了四个基本节的OTA_C的实现及链接条件 ,该方法可用于设计最平幅度及契比雪夫低通滤波器 ,其特点有 :n阶低通滤波器仅需要n+ 2个OTA元件和n个电容 ;所有OTA元件具有相同的传输电导 ;所有电容都一端接地 .最后给出的一个 5阶契比雪夫低通滤波器的设计实例及PSPICE模拟结果 ,证实了该方法的正确性 .

Organic Light-Emitting Diodes by Doping Liq into an Electron Transport Layer

Organic light emitting diodes （OLEDs） incorporating an n-doping transport layer comprised of 8-hydroxy-quin- olinato lithium （Liq） doped into 4＇ 7- diphyenyl-1,10-phenanthroline （BPhen） as ETL and a p-doping transport layer that includes tetrafluro-tetracyano-quinodimethane （F4- TCNQ） doped into 4,4′, 4″-tris （3-methylphenylphenylamono） triphe- nylamine （m-MTDATA） are demonstrated. In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency Of organic light-emitting diodes are improved significantly after introducing an n-doping （BPhen：33wt% Liq） layer as an electron transport layer （ETL） and a p-doping layer composed of m-MTDATA and F4- TCNQ as a hole transport layer （HTL）. Compared with the control device （without doping） , the current efficiency and power efficiency of the most efficient device （device C） are enhanced by approximately 51% and 89% ,respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to efficient charge balance in the emission zone.

Ferromagnetism of Mn-doped ZnO nanoparticles prepared by sol-gel process at room temperature

Mn-doped ZnO diluted magnetic semiconductor nanoparticles are prepared by an ultrasonic assisted sol-gel process.Transmission electron microscopy shows pseudo-hexagonal nanoparticles with an average size of about 24 nm.From the analysis of X-ray diffraction,the Mn-doped ZnO nanoparticles are identified to be a wurtzite structure without any impurity phases.The magnetic properties are measured by using superconducting quantum interference device.For the ZnO with 2% Mn doping concentration,a good hysteresis loop indicates fine ferromagnetism with a Curie temperature higher than 350 K.

Verifying the Franz-Wiedemann Law in the Undergraduate Laboratory

The Franz-Wiedemann law is similar to Ohm＇s law in that it applies to an important but narrow set of materials.ln 1853 R. Franz and G. Wiedemann observed that in metals the ratio of the thermal conductivity to the electrical conductivity is a constant.This observation suggests that whatever mechanism or particle is involved in the transmission of electrical current through a metal may also be responsible for the transmission of heat.ln this paper we present an inexpensive and quick experiment through which this law may be verified for copper, aluminum and zinc.

Generating Squeezed States in Solid State Circuits

We propose a scheme for generating squeezed states in solid state circuits which consist a superconducting transmission line resonator （STLR）, a superconducting Cooper-pair box （CPB） and a nanoelectromechanical resonator （NMR）. The nonlinear interaction between the STLR and the CPB can be implemented by setting the external biased flux of the CPB at some certain points. The interaction Hamiltonian between the STLR and the NMR is derived by performing Fr ohlich transformation on tile total Hamiltonian of tile combined system. Just by adiabatically keeping the CPB at the ground state, we get the standard parametric down-conversion Hamiltonian, and the squeezed states of the STLR can be easily generated, which is similar to the three-wave mixing in quantum optics.

Efficient One-Step Generation of Cluster State with Charge Qubits in Circuit QED

t We propose theoretical schemes to generate highly entangled cluster state with superconducting qubits in a circuit QED architecture. Charge qubits are located inside a superconducting transmission line, which serves as a quantum data bus. We show that large clusters state can be efficiently generated in just one step with the longrange Ising-like unitary operators. The quantum operations which are generally realized by two coupling mechanisms： either voltage coupling or current coupling, depend only on global geometric features and are insensitive not only to the thermal state of the transmission line but also to certain random operation errors. Thus high-fidelity one-way quantum computation can be achieved.

Experimental and theoretical study of the charge transport property of 4,4′-N,N′-dicarbazole-biphenyl

The hole and electron mobilities of the amorphous films of the organic semiconductor 4,4′-N,N′-dicarbazole-biphenyl (CBP) at different electric fields were measured through the time of flight (TOF) method. Based on its crystalline structure, the hole and electron mobilities of CBP were calculated. A detailed comparison between experimental and theoretical results is necessary for further understanding its charge transport properties. In order to do this, charge mobilities at zero electric field, μ(0), were deduced from experimental data as a link between experimental and theoretical data. It was found that the electron transport of CBP is less affected by traps compared with its hole transport. This unusual phenomenon can be understood through the distributions of frontier molecular orbitals. We showed that designing materials with frontier molecular orbitals localized at the center of the molecule has the potency to reduce the influence of traps on charge transport and provide new insights into designing high mobility charge transport materials.

Molecule bridged graphene/Ag for highly conductive ink

Printing is a method of additive manufacturing that can reduce material costs and environmental contamination during the fabrication process.Ag ink is commonly used in printed electronics,such as interconnects,inductors,and antennas.However,the high cost of noble Ag restricts its massive applications.To reduce the cost of the state-of-the-art Ag ink and realize large-scale manufacturing,we develop a molecule-bridged graphene/Ag(MB-G/A)composite to produce highly conductive and cost-effective paperbased electronics.Graphene can be used to substitute part of Ag nanoparticles to reduce costs,form a conducive percolation network,and retain a reasonable level of conductivity.We adopt cysteamine as a molecular linker,because it anchors on the surface of graphene via the diazonium reaction.Additionally,the thiol functional group on the other end of cysteamine can bond to a Ag atom,forming a molecular bridge between graphene and Ag and promoting electron transport between Ag and graphene.As a result,the maximum conductivity of MB-G/A inks can reach 2.0×10^(5)S m^(−1),enabling their successful application in various printable electronics.In addition,the optimum MB-G/A ink costs less than half as much as pure Ag inks,showing the great potential of MB-G/A ink in commercial electronic devices.

Simulation of the spin-boson model with superconducting phase qubit coupled to a transmission line

Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase transition.We design the spinboson model by using a superconducting phase qubit coupled to a semi-infinite transmission line,which is regarded as a bosonic reservoir with a continuum spectrum.By tuning the bias current or the coupling capacitance,the quantum KT transition can be directly detected through tomography measurement on the states of the phase qubit.We also estimate the experimental parameters using the numerical renormalization group method.