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Your search keyword '"Huang, Jiankun"' showing total 180 results
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180 results on '"Huang, Jiankun"'

11. Efficient numerical simulations on the forest barrier for seismic wave attenuation: engineering safe constructions

Author

Al-Shami, Qahtan, Huang, Jiankun, Amran, Mugahed, Mugahed, Saleh, Alluqmani, Ayed Eid, Al-Haaj, Mohammed, Gamil, Yaser, Abdelgader, Hakim S., Al-Shami, Qahtan, Huang, Jiankun, Amran, Mugahed, Mugahed, Saleh, Alluqmani, Ayed Eid, Al-Haaj, Mohammed, Gamil, Yaser, and Abdelgader, Hakim S.

Abstract

This paper aims to elucidate the clear visibility of attenuating seismic waves (SWs) with forest trees as natural metamaterials known as forest metamaterials (FMs) arranged in a periodic pattern around the protected area. In analyzing the changeability of the FM models, five distinct cases of “metawall” configurations were considered. Numerical simulations were conducted to study the characteristics of bandgaps (BGs) and vibration modes for each model. The finite element method (FEM) was used to illustrate the generation of BGs in low frequency ranges. The commercial finite element code COMSOL Multiphysics 5.4a was adopted to carry out the numerical analysis, utilizing the sound cone method and the strain energy method. Wide BGs were generated for the Bragg scattering BGs and local resonance BGs owing to the gradual variations in tree height and the addition of a vertical load in the form of mass to simulate the tree foliage. The results were promising and confirmed the applicability of FEM based on the parametric design language ANSYS 17.2 software to apply the boundary conditions of the proposed models at frequencies below 100 Hz. The effects of the mechanical properties of the six layers of soil and the geometric parameters of FMs were studied intensively. Unit cell layouts and an engineered configuration for arranging FMs based on periodic theory to achieve significant results in controlling ground vibrations, which are valuable for protecting a large number of structures or an entire city, are recommended. Prior to construction, protecting a region and exerting control over FM characteristics are advantageous. The results exhibited the effect of the ‘trees’ upper portion (e.g., leaves, crown, and lateral bulky branches) and the gradual change in tree height on the width and position of BGs, which refers to the attenuation mechanism. Low frequency ranges of less than 100 Hz were particularly well suited for attenuating SWs with FMs. However, an engineering metho, Validerad;2024;Nivå 1;2024-03-26 (hanlid);Funder: Prince Sattam bin Abdulaziz University (PSAU/2023/R/1444); Beijing Municipal Education Commission; Islamic University of Madinah, Saudi Arabia;Full text license: CC BY

Published
2024
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23. Study on microstructures and mechanical strength of MgO–C refractories with cobalt‐loaded expanded graphite.

Author

Wang, Yilong, Zhang, Wenli, Zeng, Xiongfeng, Huang, Jiankun, Chen, Yuejun, Wei, Hengyong, and Tu, Junbo

Subjects
CARBON nanotubes, GRAPHITE, REFRACTORY materials, MICROSTRUCTURE, ALUMINUM powder, MAGNESITE, COBALT
Abstract

Herein, MgO–C refractories were prepared using fused magnesite, aluminum powder, and silicon powder as antioxidants and different kinds of graphite as carbon sources at 1200°C–1600°C. The microstructure and mechanical strength of MgO–C refractories were studied. The results showed that using cobalt‐loaded expanded graphite as partial carbon source, carbon nanotubes (CNTs) were formed in situ in MgO–C refractories at 1200°C, and the CNTs gradually reacted with Si to form SiC fibers over 1400°C. Consequently, the mechanical strength of MgO–C refractories was significantly improved. [ABSTRACT FROM AUTHOR]

Published
2024
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36. Surface-wave attenuation zone of layered periodic structures and feasible application in ground vibration reduction

Author

Huang, Jiankun, Liu, Wen, and Shi, Zhifei

Subjects
Wave propagation -- Models -- Analysis, Business, Construction and materials industries
Abstract

ABSTRACT A layered periodic structure is proposed to construct a periodic wave barrier, which is defined by extended typical cells consisting of two different components. The periodic structure with reasonable [...]

Published
2017
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42. Engineering an alcohol dehydrogenase with enhanced activity and stereoselectivity toward diaryl ketones: reduction of steric hindrance and change of the stereocontrol element

Author

Lei Shao, Xiangguo Meng, Kai Wu, Rong Chen, Huang Jiankun, and Zhijun Yang

Subjects
Steric effects, chemistry.chemical_classification, Halogen bond, biology, 010405 organic chemistry, Stereochemistry, Chemistry, Enantioselective synthesis, 010402 general chemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Biocatalysis, biology.protein, Non-covalent interactions, Stereoselectivity, Alcohol dehydrogenase
Abstract

Steric hindrance in the binding pocket of an alcohol dehydrogenase (ADH) has a great impact on its activity and stereoselectivity simultaneously. Due to the subtle structural difference between two bulky phenyl substituents, the asymmetric synthesis of diaryl alcohols by bioreduction of diaryl ketones is often hindered by the low activity and stereoselectivity of ADHs. To engineer an ADH with practical properties and to investigate the molecular mechanism behind the asymmetric biocatalysis of diaryl ketones, we engineered an ADH from Lactobacillus kefiri (LkADH) to asymmetrically catalyse the reduction of 4-chlorodiphenylketones (CPPK), which are not catalysed by the wild type (WT) enzyme. Mutants seq1–seq5 with gradually increased activity and stereoselectivity were obtained through iterative “shrinking mutagenesis.” The final mutant seq5 (Y190P/I144V/L199V/E145C/M206F) demonstrated the highest activity and excellent stereoselectivity of >99% ee. Molecular simulation analyses revealed that mutations may enhance the activity by eliminating steric hindrance, inducing a more open binding loop and constructing more noncovalent interactions. The pro-R pose of CPPK with a halogen bond formed a pre-reaction conformation more easily than the pro-S pose, resulting in the high ee of (R)-CPPO in seq5. Moreover, different halogen bonds formed due to the different positions of chlorine substituents, resulting in opposite substrate binding orientation and stereoselectivity. Therefore, the stereoselectivity of seq5 was inverted toward ortho- rather than para-chlorine substituted ketones. These results indicate that the stereocontrol element of LkADH was changed to recognise diaryl ketones after steric hindrance was eliminated. This study provides novel insights into the role of steric hindrance and noncovalent bonds in the determination of the activity and stereoselectivity of enzymes, and presents an approach producing key intermediates of chiral drugs with practical potential.

Published
2020
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