Seismic performance of double- skin steel- concrete composite box piers: Part Ⅰ——Bidirectional quasi-static testing

To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.

Design,synthesis and properties of novel organic small molecule photovoltaic materials based on diketopyrrolopyrrole-fluorene

Two novel organic small molecule donor materials(FLU),TDPP and(DFLU)_(2)TDPP based on diketopyrrolopyrrole-fluorene were designed and synthesized successfully.The D-D-π-A-π-D-D type molecule(DFLU)_(2)TDPP was constructed based on the D-π-A-π-D type molecule(FLU)_(2)TDPP by a backbone extension strategy.The optical absorption,electrochemistry and photovoltaic properties of the two novel materials were investigated in detail.Both(FLU)_(2)TDPP and(DFLU)_(2)TDPP show narrow energy gaps of1.71 and 1.64 eV,respectively.Compared to(FLU)_(2)TDPP,the photovoltaic device based on(DFLU)_(2)TDPP/PC_(71)BM exhibited a higher power conversion efficiency of 2.27%due to its excellent optical absorption,narrow band gap and balanced carrier mobility.This study indicates that skeleton extension strategy is an effective strategy to broaden the molecular absorption range and improve device performance.

Liquid-phase epitaxy of metal organic framework thin films

Metal-organic framework(MOF) thin films are multilayer materials ranging from nanometers to micrometers in thickness,physically or chemically adhesive to a(functionalized) substrate and,in an ideal case,exhibiting low roughness and high homogeneity.Various innovative approaches have been developed for MOF thin film fabrication.Among these advanced materials,surface-attached metal-organic frameworks(SURMOFs) are an important class of MOF films.SURMOFs,fabricated in a step-by-step liquid phase epitaxial(LPE) fashion by alternating deposition of metal and organic linker precursors on a functionalized substrate,for example,thiolate-based self-assembled monolayers(SAMs),have already exhibited their utility in both research and potential applications.SURMOFs combine surface science and the chemistry of MOFs,possessing the following unique advantages that cannot be accessed through other methods:(i) precisely controlling thickness,roughness and homogeneity as well as growth orientation,(ii) studying of MOF growth mechanism,(iii) modifying/tailoring MOFs' structures during the SURMOF growth and thus creating customizable properties,and(iv) existing in the form of thin film/membrane for direct applications,for example,as sensors.This review discusses the oriented and crystalline SURMOFs fabricated by LPE approach,covering their preparation,growth mechanism,and characterization methodology as well as applications based upon the most newly updated knowledge.