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.

A MnO2-based catalyst with H2O resistance for NH3-SCR: Study of catalytic activity and reactants-H2O competitive adsorption

Abstract: MnO2 with interlayer Ce3+ cation (Ce-MnO2) was synthesized by ion exchange approach. The Ce-MnO2 exhibited better low-temperature NH3-SCR catalytic activity as compared to Ce0.38Mn0.62O2-CP prepared by co-precipitation. The good performance was due to easy supply of labile oxygen species generated by migration of Ce species in Ce-MnO2 catalyst, which could promote the oxidation of reactants. The special structure of Ce-MnO2 promoted better properties in terms of low-temperature reduction properties, lower element species, adsorption capacity of reactants and surface acid sites, which was beneficial to NH3-SCR at low-temperature. It also showed superior H2O resistance with NOx conversion above 90 % below 150 °C. The competitive adsorptions between H2O and reactants over both of Ce-containing catalysts were investigated by in-situ DRIFT and TPD. The results indicated NOx with strong competitive adsorption on Ce-MnO2 surface than H2O. No competitive adsorption between NH3 and H2O over both of Ce-containing catalysts was also observed, different from previous reports.

3D printing of hydroxyapatite scaffolds with good mechanical and biocompatible properties by digital light processing

Abstract: Hydroxyapatite is a scaffold material widely used in clinical repair of bone defects, but it is difficult for traditional methods to make customized artificial bone implants with complicated shapes. 3D printing biomaterials used as personalized tissue substitutes have the ability to promote and enhance regeneration in areas of defected tissue. The present study aimed at demonstrating the capacity of one 3D printing technique, digital light processing (DLP), to produce HA scaffold. Using HA powder and photopolymer as raw materials, a mixture of HA mass ratio of 30 wt% was prepared by viscosity test. It was used for forming ceramic sample by DLP technology. According to differential scanning calorimetry and thermal gravity analysis, it was revealed that the main temperature range for the decomposition of photopolymer was from 300 to 500 °C. Thus, the two-step sintering process parameters were determined, including sintering temperature range and heating rate. XRD analysis showed that the phase of HA did not change after sintering. SEM results showed that the grain of the sintered ceramic was compact. The compression model was designed by finite element analysis. The mechanical test results showed that the sample had good compression performance. The biological properties of the scaffold were determined by cell culture in vitro. According to the proliferation of cells, it was concluded that the HA scaffold was biocompatible and suitable for cell growth and proliferation. The experimental results show that the DLP technology can be used to form the ceramic scaffold, and the photopolymer in the as-printed sample can be removed by proper high-temperature sintering. The ceramic parts with good compression performance and biocompatibility could be obtained.

Microporous Hydrogen-Bonded Organic Framework for Highly Efficient Turn-Up Fluorescent Sensing of Aniline.

Abstract: A microporous three-dimensional (3D) hydrogen-bonded organic framework (HOF-20) has been constructed from an aromatic-rich tetratopic carboxylic acid, 5-(2,6-bis(4-carboxyphenyl)pyridin-4-yl)isophthalic acid (H4BCPIA) The activated HOF-20a has a moderately high Brunauer-Emmett-Teller (BET) surface area of 1323 m2 g-1 and excellent stability in water and HCl aqueous solution HOF-20 exhibits highly efficient turn-up fluorescent sensing of aniline in water with a detection limit of 224 μM and is selective toward aniline in the presence of aromatic interferents, owing to the hydrogen bonding and edge-to-face π-π stacking interactions between the HOF-20 host and the guest aniline molecules, as demonstrated in the single-crystal X-ray structure of HOF-20⊃aniline Density functional theory (DFT) calculations further demonstrate that the recognition of aniline molecules by HOF-20 could restrict the rotation of the aromatic rings in H4BCPIA linkers, reducing the nonradiative decay pathways upon photoexcitation and subsequently enhancing the fluorescence intensity

Achieving zT > 2 in p‐Type AgSbTe2−xSex Alloys via Exploring the Extra Light Valence Band and Introducing Dense Stacking Faults

Abstract: Through simultaneously enhancing the power factor by engineering the extra light band and enhancing phonon scatterings by introducing a high density of stacking faults, a record figure-of-merit over 2.0 is achieved in p-type AgSbTe2−xSex alloys. Density functional theory calculations confirm the presence of the light valence band with large degeneracy in AgSbTe2, and that alloying with Se decreases the energy offset between the light valence band and the valence band maximum. Therefore, a significantly enhanced power factor is realized in p-type AgSbTe2−xSex alloys. In addition, transmission electron microscopy studies indicate the appearance of stacking faults and grain boundaries, which together with grain boundaries and point defects significantly strengthen phonon scatterings, leading to an ultralow thermal conductivity. The synergetic strategy of simultaneously enhancing power factor and strengthening phonon scattering developed in this study opens up a robust pathway to tailor hermoelectric performance.