Regioselective Iodination of Activated Arenes Using Phenyl Trimethylammonium Dichloroiodate in Ionic Liquid Under Microwave Irradiation

Abstract

The regioselective iodination of activated arenes has been achieved in the presence of phenyltrimethylammonium dichloroiodate and ionic liquid. The reaction has been carried out by both conventional heating as well as by microwave irradiation.     

Efcient Multipartite Polarization Entanglement Distribution Over Arbitrary Noise Channel

We present an efcient faithful multipartite polarization entanglement distribution protocol over an arbitrary noisy channel.The spatial degree of freedom is used to carry the entanglement during the transmission.We describe the principle by distributing n-qubit Greenberge–Horne–Zeilinger state and n-qubit W state.Our scheme can be used to distribute arbitrary n-qubit entangled states to n distant locations.The remote parties can obtain maximally entangled states deterministically on the polarization of photons.Only passive linear optics are employed in our setup,which makes our scheme more feasible and efcient for practical application in long distance quantum communication.     

A Convenient Procedure for N-Amination of 4-OXO-1,4-Dihydroquinolines

A high yielding N-amination of quinolones at low temperature via the use of O-mesitylenesulfonylhydroxylamine is reported.     

Distributed NGD active circuit for RF-microwave communication

This paper is aimed to the investigation on innovative distributed negative group delay (DNGD) circuits for RF communication. Thanks to the analogy between the lumped and distributed circuits, NGD circuit topologies were identified. By using the S-parameter theory, analysis and synthesis methods of these topologies are proposed. The DNGD circuits developed are mainly comprised of a transistor combined with a series resistance ended by a stub. Then, synthesis relations enabling to determine the NGD circuit parameters from the desired NGD and gain values are established. As application, an active phase shifter (PS) operating independently with the frequency based on the cascade of PGD and NGD devices was synthesized. First, an NGD PS with transmission phase of (135 ± 5)° around 2.56 GHz over the bandwidth of about 1.02 GHz was obtained. Then, a two-stage DNGD PS exhibiting 90° with ±10° flatness from 4.1 GHz to 6.8 GHz was designed. The DNGD circuit presented can be used in various telecommunication areas notably for correcting RF/numerical signal delays in the RF-microwave analogue-digital devices.     

Determination of Cadmium in Plant Tissues by Electrothermal Atomisation Atomic Absorption Spectrometry with Matrix/Analyte Modification and Smith-Hieftje Background Correction

Abstract

Pressure decomposition in a microwave oven provides a rapid means of sample preparation for plant tissue analyses. The use of delayed atomisation cuvettes, Smith-Hieftje background correction and matrix/analyte modification enables accurate determinations of cadmium concentrations in plant materials to be made. However, care should be taken to restrict the concentrations of modifier used, as too high a concentration may lead to problems with both tube life and over-correction by the Smith-Hieftje background correction system.     

MICROWAVE ASSISTED OXIDATION OF BENZALDEHYDES UNDER SOLVENT-FREE CONDITION USING OXONE®/WET-ALUMINA

The solventless oxidation of benzaldehydes to carboxylic acids using oxone/wet-alumina under microwave irradiations is described.     

Shear and extensional rheology of entangled polymer melts: Similarities and differences

This work extends our previous understanding concerning the nonlinear responses of entangled polymer solutions and melts to large external deformation in both simple shear and uniaxial extension. Many similarities have recently been identified for both step strain and startup continuous deformation, including elastic yielding, i.e., chain disentanglement after cessation of shear or extension, and emergence of a yield point during startup deformation that involves a deformation rate in excess of the dominant molecular relaxation rate. At a sufficiently high constant Hencky rate, uniaxial extension of an entangled melt is known to produce window-glass-like rupture. The present study provides evidence against the speculation that chain entanglements tie up into "dead knots" in constant-rate extension because of the exponentially growing chain stretching with time. In particular, it is shown that even Instron-style tensile stretching, i.e., extending a specimen by applying a constant velocity on both ends, results in rupture. Yet, in the same rate range, the same entangled melt only yields in simple shear, and the resulting shear banding is clearly not a characteristic of rupture. Thus, we conclude that chain entanglements respond to simple shear in the manner of yielding whereas uniaxial extension is rather effective in causing some entanglements to lock up, making it impossible for the entanglement network to yield at high rates.     

对称转台在微波器件加工过程中的应用

为提高微波器件的加工合格率,将对称转台应用于微波器件加工的硬件设施中,并分析了对称加工的特点。以某微波器件加工为例,简要介绍了对称转台的应用。实践证明,对称转台的使用提高了微波器件的加工质量、降低了成本。