Beijing University of Technology

About: Beijing University of Technology is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: Microstructure & Computer science. The organization has 31929 authors who have published 31987 publications receiving 352112 citations. The organization is also known as: Běijīng Gōngyè Dàxué & Beijing Polytechnic University.

Reactivity and Mechanism Studies of Hydrogen Evolution Catalyzed by Copper Corroles

Abstract: Several copper corrole complexes were synthesized, and their catalytic activities for hydrogen (H2) evolution were examined. Our results showed that substituents at the meso positions of corrole macrocycles played significant roles in regulating the redox and thus the catalytic properties of copper corrole complexes: strong electron-withdrawing substituents can improve the catalysis for hydrogen evolution, while electron-donating substituents are not favored in this system. The copper complex of 5,15-pentafluorophenyl-10-(4-nitrophenyl)corrole (1) was shown to have the best electrocatalytic performance among copper corroles examined. Complex 1 can electrocatalyze H2 evolution using trifluoroacetic acid (TFA) as the proton source in acetonitrile. In cyclic voltammetry, the value of icat/ip = 303 (icat is the catalytic current, ip is the one-electron peak current of 1 in the absence of acid) at a scan rate of 100 mV s–1 and 20 °C is remarkable. Electrochemical and spectroscopic measurements revealed that 1 ...

State-of-the-art of 3D printing technology of cementitious material—An emerging technique for construction

Abstract: In recent few years, significant improvement has been made in developing largescale 3D printer to accommodate the need of industrial-scale 3D printing. Cementitious materials that are compatible with 3D printing promote rapid application of this innovative technique in the construction field with advantages of cost effective, high efficiency, design flexibility and environmental friendly. This paper firstly reviews existing 3D printing techniques that are currently being used in commercial 3D printers. It then summarizes three latest development of largescale 3D printing systems and identifies their relationships and limiting factors. Thereafter, critical factors that are used to evaluate the workability and printable performance of cementitious materials are specified. Easy-extrusive, easy-flowing, well-buildable, and proper setting time are significant for cementitious material to meet the critical requirements of a freeform construction process. Finally, main advantages, potential applications and the prospects of future research of 3D printing in construction technology are suggested. The objective of this work is to review current design methodologies and operational constraints of largescale 3D printing system and provide references for optimizing the performance of cementitious material and promote its responsible use with largescale 3D printing technology.

Concentration gradient generation methods based on microfluidic systems

Abstract: Various concentration gradient generation methods based on microfluidic systems are summarized in this paper. The review covers typical structural characteristics, gradient generation mechanisms, theoretical calculation formulas, applicable scopes, and advantages and disadvantages of these approaches in detail. According to the type of reagents involved, these methods are classified into mono-phase methods and multi-phase methods, both of which can be implemented by alternative protocols, while the latter methods particularly refer to droplet-based platforms. For mono-phase methods, the shearing effect would be presented if there are flowing streams in the gradient generation channel. Therefore, the generation speed of channels with moving liquids is relatively fast, which is suitable for dynamic gradients but accompanied by shearing as well, while channels without flowing streams would avoid shearing but are prone to static gradient generation determined by the low speed. Newly developed droplet-based generation systems could provide isolated droplets to avoid the disturbances from the outside continuous phase, however, they require precise droplet generation and control modules. Thereby the most suitable platform can be chosen according to the specific application, while the advantages of different methods could be combined to evade the defects and improve the precision of a single structure.