A Study of Substitution Site of Sn in YBa_2(Cu_(1-x)Sn_x)_3O_y Superconductors by Positron Annihilation Technique

It is one of the important ways that the foreign elements can be used as a probe to be substituted into the lattice so as to obtain the information about the electronic and crystal structure of the cuprate oxide superconductors. Obviously, it is essential to determining the real substituted site by foreign elements in discussion of the substitution effect. It is known that the positron annihilation technique (PAT) is highly sensitive to the changes in electronic and defect structure of the materials. Since Jean et al. reported

A new type counter electrode for dye-sensitized solar cells

A new type counter electrode for dye-sensitized solar cells (DSCs) was proposed which consists of substrate, aluminum film and platinum film. The new type counter electrode can obviously improve the photoelectric conversion efficiency of DSCs from 3.46% to 7.07% under the standard AM1.5 irradiation condition. Advantages and shortcomings of this new type counter electrode in terms of electrical properties, optical properties and anti-corrosive properties were analyzed. As a result, some improvements were proposed.

Noble gas as a functional dopant in ZnO

Owing to fully occupied orbitals,noble gases are considered to be chemically inert and to have limited effect on materials properties under standard conditions.However,using first-principles calculations,we demonstrate herein that the insertion of noble gas(i.e.He,Ne,or Ar)in ZnO results in local destabilization of electron density of the material driven by minimization of an unfavorable overlap of atomic orbitals of the noble gas and its surrounding atoms.Specifically,the noble gas defect(interstitial or substitutional)in ZnO pushes the electron density of its surrounding atoms away from the defect.Simultaneously,the host material confines the electron density of the noble gas.As a consequence,the interaction of He,Ne,or Ar with O vacancies of ZnO in different charge states q(ZnO:VO^(q))affects the vacancy stability and their electronic structures.Remarkably,we find that the noble gas is a functional dopant that can delocalize the deep in-gap VO^(q) states and lift electrons associated with the vacancy to the conduction band.

Design and fabrication of a vigorous“cavitation-on-a-chip”device with a multiple microchannel configuration

Hydrodynamic cavitation is one of the major phase change phenomena and occurs with a sudden decrease in the local static pressure within a fluid.With the emergence of microelectromechanical systems(MEMS),high-speed microfluidic devices have attracted considerable attention and been implemented in many fields,including cavitation applications.In this study,a new generation of‘cavitation-on-a-chip’devices with eight parallel structured microchannels is proposed.This new device is designed with the motivation of decreasing the upstream pressure(input energy)required for facile hydrodynamic cavitation inception.Water and a poly(vinyl alcohol)(PVA)microbubble(MB)suspension are used as the working fluids.The results show that the cavitation inception upstream pressure can be reduced with the proposed device in comparison with previous studies with a single flow restrictive element.Furthermore,using PVA MBs further results in a reduction in the upstream pressure required for cavitation inception.In this new device,different cavitating flow patterns with various intensities can be observed at a constant cavitation number and fixed upstream pressure within the same device.Moreover,cavitating flows intensify faster in the proposed device for both water and the water–PVA MB suspension in comparison to previous studies.Due to these features,this next-generation‘cavitation-on-a-chip’device has a high potential for implementation in applications involving microfluidic/organ-on-a-chip devices,such as integrated drug release and tissue engineering.