CO2 Adsorption on the B12N12 Nanocage Encapsulated with Alkali Metals: A Density Functional Study

Haiyan Zhu,Qiyan Zhang,Qinfu Zhao,He Zhao,Yifan Feng,Bingbing Suo,Huixian Han,Qi Song,Yawei Li,Wenli Zou,Haiyan Zhu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

Density functional theory (DFT) calculations have been carried out to study the capacity of the B12N12 nanocage encapsulated with alkali metals (Li, Na, K) for the CO2 adsorption and activation. It is found that after encapsulating alkali metals, the alkali metal atoms are closer to one side of clusters instead of exactly lying at the center, and a considerable charge transfers from the inner alkali metal atoms to the B12N12 cage. Besides, the HOMO–LUMO gap (HLG) values of Li@B12N12, Na@B12N12 and K@B12N12 are decreased to about 6 eV, being much smaller than that of the pristine B12N12. Although the geometry structure parameters and the energy differences of M06-2X are slightly different from the ones of ωB97X-D, some identical results of two kinds of functional can be obtained. CO2 can be adsorbed chemically and physically on majority bonds of all the clusters, except for some bonds with large change in bond length and bond indices. The encapsulation of alkali-metal atoms may enhance the physical and chemical adsorption of CO2 on the surface of the clusters, in which Na@B12N12 and K@B12N12 are the most powerful physical and chemical adsorbent for CO2, respectively.

Microstructural Refinement and Performance Improvement of Cast n-Type Bi2Te2.79Se0.21 Ingot by Equal Channel Angular Extrusion

Xiaoming Hu,Xi’an Fan,Bo Feng,Dong Kong,Peihai Liu,Rusong Li,Yanglin Zhang,Guangqiang Li,Yawei Li 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

How to form a uniform fine-grained structure in n-type polycrystalline Bi2Te3based alloys to stabilize and improve thethermoelectric properties is the burning issue to be solved. In the present work, equal channel angular extrusion (ECAE)method was used to extrude the cast ingot directly at various temperatures to obtain the BiTeSe polycrystalline bulk alloyswith uniform microstructure. The initial lamellae coarse grains (hundreds microns to several millimeters) were efficiently anduniformly refined to a minimum of 4.07 μm at 703 K, which fully demonstrates the feasibility of grain refinement by ECAEfor cast n-type BiTeSe ingot. The average grain size of the extruded billets rapidly increased from 5.35 to 29.55 μm withthe increase of extrusion temperature from 703 to 823 K. Meanwhile, the behavior of abnormal grain growth became moreevident as the extrusion temperature increased because the growth rate increased more rapidly than the rate of nucleation. As the extrusion temperature increased, the Vickers hardness decreased gradually due to grain coarsening. BiTeSe alloysextruded at 703 K achieved the maximum Vickers hardness of 59.8 HV0.05,which was nearly three times higher than that ofthe initial cast ingot. All extruded BiTeSe billets possessed the much higher dimensionless figure of merit (ZT), comparedwith the initial cast ingot due to the simultaneously optimization of electrical and thermal transport performances caused byECAE process. Finally, the specimen extruded at 823 K achieved the maximum ZT of 0.685 at 383 K.

CircTRRAP (hsa_circ_0081234) participates in prostate cancer progression and glycolysis by HOXA1 via functioning as a miR‑515‑5p sponge

Li Zhihui,Guan Yawei,Teng Jingfei,Jia Zhuomin,Zhang Guohui,Ai Xing 한국응용생명화학회 2022 Applied Biological Chemistry (Appl Biol Chem) Vol.65 No.4

Dysregulated circular RNAs (circRNAs) are implicated in prostate cancer (PCa) progression. Hsa_circ_0081234 (circTRRAP) has been revealed as a facilitator in PCa, but the mechanisms associated with circTRRAP in PCa progression are largely unclear. The present study was to explore the regulatory mechanism of circTRRAP-mediated PCa progression. A total of 50 PCa tissues and normal tissues were collected. RNA levels of circTRRAP, microRNA (miR)-515-5p and homeobox A1 (HOXA1) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell viability, proliferation, migration, and invasion were estimated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, 5-ethynyl-2ʹ-deoxyuridine (EdU) and transwell assays, respectively. Cell glycolysis was assessed by measuring glucose uptake and lactate production. The target interaction between circTRRAP or HOXA1 and miR-515-5p was investigated by the dual-luciferase reporter assay. We observed the overt upregulaiton of circTRRAP in PCa samples and cells. Silencing of circTRRAP lowered tumor growth in vivo and restrained PCa cell viability, proliferation, migration, invasion, and glycolysis in vitro. miR-515-5p was negatively regulated by circTRRAP and its deficiency reversed the inhibiting effects of circTRRAP knockdown on PCa cell malignancy and glycolysis. HOXA1 was confirmed as a miR-515-5p target and miR-515-5p overexpression lessened PCa cell malignancy and glycolysis by decreasing HOXA1 expression. Importantly, circTRRAP mediated HOXA1 expression by functioning as a miR-515-5p sponge. In conclusion, circTRRAP took part in PCa progression and glycolysis through mediating the miR-515-5p/HOXA1 axis, suggesting that circTRRAP can serve as a potential therapeutic target for PCa patients.

Effect of Perforating an Intake Pipe on the Interior Noise of a Passenger Car

Zhu Yawei,Lu Chihua,Liu Zhien,Xie Liping,Li Xiaolong 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4

The intake pipes designed by some experienced engineers have small holes. However, the role of these small holes is yet to be fully understood by most engineers. At present, the only research on this issue is also controversial. This work aims to reveal the effect of perforating an intake pipe on the interior noise and provide some suggestions to automotive engineers when applying this method. First, the effect of these small holes on the source strength of the intake nozzle and perforated region is theoretically analyzed. Thereafter, the noise transfer functions of the intake nozzle and perforated region to the target response point in the cab are measured on the basis of the reciprocity principle. Finally, the effect of perforating the intake pipe on the interior noise is studied by simulating the intake noise of the experimental car with an external sound source. Results show that perforating the intake pipe can increase the order noise component of the intake noise and reduce the mid-high frequency noise in the cab, thereby improving the powerful sound quality and reducing the feeling of noisy.

Analysis of thermal performance and thermal stress using two-dimensional thermoelastic model for a 50 MWe external cylindrical solar receiver

Hao Zhou,Yuhang Zuo,Yawei Li,Mingxi Zhou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

The thermal stress arisen from highly inhomogeneous solar radiation and temperature distribution during operation is mainly responsible for the failure of the central receiver. In the present study, the analytical approximation method, finite volume method and 2D thermoelastic analytical approach were used in combination to obtain the thermal characteristics of a 50 MWe external cylindrical receiver. The results demonstrated that the direct normal irradiance and tube surface absorptivity significantly affected the thermal stress. The axial distribution of the equivalent thermal stress at θ = 0° consisted with the surface solar flux distribution, and the maximum equivalent stress was underestimated by 30.0 % with the homogeneous surface solar flux distribution. Compared with molten salt flowing into the receiver from the south, the maximum equivalent stress and maximum wall temperature of molten salt flowing from the north are 16.3 % higher and 8.1 % lower, respectively.

Experimental and Numerical Simulation Study on Mechanical Properties of Shallow Slope Root-soil Composite in Qinghai Area

Yuan Sun,Hui Li,Zhifeng Cheng,Jianpeng Dong,Yawei Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Natural disasters such as landslides often occur in Qinghai under the double deterioration ofearthquake and freeze-thaw cycles, ecological slope protection is an effective way to preventand control this type of disaster. In this paper, the mechanical properties of root-soilcomposites are investigated experimentally using triaxial apparatus and dynamic single shear(DSS) apparatus, and based on the discrete element method, a contact model more suitablefor reinforced soil materials is proposed to study the dynamic properties of root-soilcomposites under cyclic shear from a fine viewpoint. Based on the results of the study, thefollowing conclusions were drawn: 1) The presence of roots under the action of freeze-thawcycles increases the strength properties of the soil. At the same number of freeze-thaw cycles,the shear strength and cyclic resistance of the root-soil composites are higher than those of theloess. And the strength of the root-soil composites decreases with the increase of the numberof freeze-thaw cycles and then flattens out; 2) The proposed contact model can bettersimulate the softening effect of reinforced loess material under cyclic shear, which is moresuitable for simulating the mechanical behavior of loess and laying the foundation for furtherstudy of reinforced loess material from a fine viewpoint.; 3) The presence of the root systemwill improve the stability of the slope soil, and the root system will have a positive effect on theshear strength of the soil when the moisture content is within a certain range. The presence ofthe root system also increases the cyclic resistance of the soil. Under the same cyclic shearstress conditions, the number of damage cycles of the root-soil composites is higher than thatof the loess, the cumulative shear strain is less than that of the loess. However, the root systemno longer exerts positive effects under saturated conditions. The research results can providesome guidance for the construction of ecological slopes in loess areas, and provide a new wayto investigate the dynamic properties of root-soil composites from a fine viewpoint.