3D printed MXene (Ti2AlN)/polycaprolactone composite scaffolds for in situ maxillofacial bone defect repair

Zhimin Xu,Yingxin Zhang,Huanyan Dai,Yu Wang,Yujie Ma,Shuang Tan,Bing Han 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Obtaining a safe and reliable scaffold that can be rapidly fabricated and used for clinical bone defect repairhas always been a challenge. In this study, polycaprolactone (PCL) composite scaffolds with various MXene(Ti2AlN) contents were prepared using 3D printing technology. The effects of different contents of Ti2AlNon the mechanical properties, hydrophilicity, cytocompatibility, and osteogenic differentiation abilitywere systematically studied and analysed. In vitro experiments showed that scaffolds containing 5%Ti2AlN (PCL@5#Ti2AlN) obtained the best cell adhesion and proliferation ability and significantly upregulatedthe alkaline phosphatase (ALP) level. In vivo experiments of tibial defect repair in rats showed thatthe PCL scaffold containing 5% Ti2AlN (PCL@5#Ti2AlN) could significantly promote the formation of newbone, and the experimental results of rabbit maxillofacial bone defect repair further proved that thePCL@5#Ti2AlN scaffold could effectively promote the repair of bone defects. Transcriptome analysis indicatedthat Ti2AlN may promote osteogenic differentiation by the Wnt/b-catenin signaling pathway andcalcium-binding proteins. These findings suggest that Ti2AlN/PCL composite scaffolds with improvedin situ bone repair ability represent an intelligent strategy for bone defect repair.

Research on the Law of Mining Induced Water Conduction Fissure in Arid Mining Area, China

( Xu Zhimin ),( Sun Yajun ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

With the focus on the gradual westward shifting of coal resources development in China, the western region has become the main production areas. In general, the ecological environment is relatively weak due to the low precipitation and high evaporation. Taking the Dananhumining area in Hami coalfield, Xinjiang, as an example, in view of the late diagenesis time, low physical intensity and easily muddy disintegration of Jurassic coal-rich strata in this area, similar material simulation and numerical simulation are used. Based on the field observation and comparison of the neighboring coalmines, several significant rules are studied including the development and evolution process, the development height and morphological characteristics, the permeability evolution law in roof water flowing fractured zone and the water protection during coal mining (water-preserved mining).The results shows that in the Jurassic coal-rich strata, the development ratio of water flowing fractured fissure is generally between 13.09 and 15.67, and the overall morphology is characterized by “terrace-type”. Fracture and permeability coefficient evolution in the range of mining impacts reflect the characteristics of “stable increase-fluctuation-recovery stability”, and the permeability coefficient of aquifer increases obviously reaching 3-5 times within the influence range of the height of water flowing fractured zone. The main coal seam roof in the study area has the “high aquifuge under multi-aquifer structure” structural characteristics, which possess the basic hydro-geological preconditions for water retention. Combined with the protection seam’ stability, the upper aquifer of iii-1 static reserves, the development potential and the comprehensive evaluation of the water-preserved mining feasibility in the research area, and the significance of water protection during coal mining in arid mining area are discussed.

Content-driven Joint Allocation of Communication and Computing Resources in Vehicular Networks

Xu Zhu,Fangfang Liu,Zhimin Zeng,Caili Guo,Jiujiu Chen 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2

With the rapid growth of computer vision applications, a large amount of video data in the Internet of Vehicles scenario are used for content analysis. Tasks based on video content understanding are usually accompanied by huge amount of calculation, which put great pressure on traditional wireless communication resource and Mobile Edge Computing (MEC) server computing resource. Furthermore, existing resource allocation schemes based on Quality of Service (QoS) or Quality of Experience (QoE) may not be the best choice for the purpose of video content understanding. In this paper, we propose a joint resource allocation scheme based on Quality of Content (QoC) to maximize the accuracy of video content understanding. Due to the real-time nature of resource allocation and the variability of the environment in autonomous driving scenarios, we design a Multi-agent Distributed Q-Learning algorithm to solve such multi-constrained nonlinear programming problems. Finally, the simulation results show that our proposed QoC-based joint resource allocation scheme has better video content understanding performance.

Preparation of Interface-Assembled Carbonyl Reductase and Its Application in the Synthesis of S-Licarbazepine in Toluene/Tris-HCl Buffer Biphasic System

( Zhimin Ou ),( Jiahui Xu ),( Lihua Du ),( Lan Tang ),( Yangping Niu ),( Jian Cui ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

In this study, interface-assembled carbonyl reductase (IACR) was prepared and used in the synthesis of S-licarbazepine in a toluene/Tris-HCl biphasic system. The carbonyl reductase (CR) was conjugated with polystyrene to form a surfactant-like structure at the interface of the toluene/Tris-HCl biphasic system. The interface-assembled efficiency of IACR reached 83% when the CR (180 U/mg) and polystyrene concentration were 8 × 10² g/ml and 3.75 × 10³ g/ml, respectively. The conversion reached 95.6% and the enantiometric excess of S-licarbazepine was 98.6% when 3.97 × 10⁶ nmol/l oxcarbazepine was converted by IACR using 6% ethanol as a co-substrate in toluene/Tris-HCl (12.5:10) at 30°C and 43 ×g for 6 h. IACR could be reused efficiently five times.

Asymmetric reduction of 3-oxo-3-phenylpropionic acid ethyl ester by undifferentiated cells of white turnip in phosphate buffer/organic solvent

Zhimin Ou,Qingmei Chen,Gensheng Yang,Li Xu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

Ethyl (S)-3-hydroxy-3-phenylpropionate was synthesized by asymmetric reduction of 3-oxo-3-phenylpropionic acid ethyl ester with undifferentiated cells of white turnip in phosphate buffer/organic solvent. The conversion increased with the LogP_oct of organic solvent increase. The phosphate buffer (0.2 mol/L, pH 7.0)/dodecane was selected as optimum medium for reduction. The optimal content of dodecane in medium is 10% (v). The conversion decreased with initial substrate concentration increase. Addition of more biomass of plant cells and 10% ethanol as co-substrate can improve conversion. The plant cells can be reused well for three times. The enantiomeric excess of ethyl (S)-3-hydroxy-3-phenylpropionate reached 100% with 1% allyl bromide as inhibitor.

A 5.6 kW 11.7 kW per kg Four-Phase Interleaved Buck Converter for the Unmanned Aerial Vehicle

Cheng Xu-Feng,Peng Zhenzhen,Yang Yulong,Liang Zhimin,Wu Chaofeng,Shao Zhiwei,Wang Dianlong 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

This paper proposed a 5.6 kW 11.7 kW/kg four-phase interleaved buck converter (FPIBC) for the unmanned aerial vehicle (UAV) low-voltage power system. The UAV mainly concerns the lightweight strategy and the power density of the DC-DC converter. We proposed a comprehensive lightweight strategy with the characteristics of reduced inductor current ripples, small size of fi lter inductors and capacitors, and high output power. The output current ripples are reduced by using interleaved modulation strategy and integrated CLC fi lters cascaded to the input side and output side respectively. In addition, the aluminum based printed circuit board (PCB) is used with SMD power transistors to obtain better heat dissipation capability without fans. With abovementioned methods, the designed DC-DC converter has a power of 5.6 kW @ 0.48 kg, the powerto-weight ratio is improved to be 11.7 kW/kg, and the power density is 3 W/cm 3 . The effi ciency of this DC-DC converter is up to 95.8%.

Improvement of low-temperature NH3-SCR catalytic activity over Mn-Ce oxide catalysts supported on sewage sludge char activated with KOH and H3PO4

Junchao Xu,Xiangyang Zhang,Yunlan Sun,Hongming Long,Zhimin Zheng 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12

Pyrolysis is a very potential sludge treatment technology that is low-cost and environmentally friendly; particularly, the pyrolysis sewage sludge char (SC) can be used as a catalyst support. To improve the NO conversion efficiency of sludge char based catalysts, they were activated by potassium hydroxide and phosphoric acid, respectively. The catalysts of activated sludge char with or without Mn-Ce impregnation in the application of NO removal by lowtemperature SCR were investigated. The higher NO conversion efficiency of sludge char based Mn-Ce catalysts at low temperature were obtained. Compared with the 59% NO conversion efficiency of Mn-Ce/SC catalyst, the conversion efficiency of catalyst supported on KOH activated char (SCK) achieved 89% at 220 oC and of catalyst supported on H3PO4 activated char (SCP) reached 87% at 240 oC. The catalysts were analytically characterized using N2 adsorptiondesorption, XRD, FTIR, NH3-TPD and XPS measurements. The higher specific area, excellent dispersion of Mn-CeOx and more Brønsted acid sites are responsible for the higher NO conversion efficiency of Mn-Ce/SCK, while the higher NO conversion efficiency of Mn-Ce/SCP is enhanced by more Brønsted acid sites, oxygen-containing and some unique phosphorus-containing oxygen functional groups. It indicates that sludge char activated by KOH and H3PO4 is a potential low-temperature catalyst support.

Experimental study on the composite fouling characteristics of calcium carbonate and nanometer magnesia

Zhiming Xu,Jingtao Wang,Zhimin Han,Yu Zhao 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

In order to study the composite fouling characteristics of crystallization and particulate, the fouling characteristics of calcium carbonate (CaCO 3 ) and nanometer magnesia in the alternating elliptical axis tube were investigated experimentally. The results show that CaCO 3has obvious effect on the inhibition of the formation of particulate fouling. The asymptotic value of fouling resistance of the nanometer magnesia is the highest and the CaCO 3 is the lowest, and the composite fouling is between them. The fouling rate and the asymptotic value of composite fouling resistance decrease with the increase of the CaCO 3 concentration. The time reaches to the asymptotic value of the three experiments are similar. The variation of nanometer magnesia concentration has greater influence than the CaCO 3 concentration on the asymptotic value of composite fouling. The fouling rate and the asymptotic value of composite fouling resistance increase obviously with the increase of the nanometer magnesia concentration.

Effect of dielectric barrier discharge parameters on degradation efficiency of ethyl acetate

Deng, Xu,Lu, SiHeng,Zheng, Kun,Yu, ZhiMin Urban Science Institute 2019 도시과학 Vol.8 No.2

Using self-made coil dielectric barrier discharge reactor, the removal efficiency of ethyl acetate under simulated experimental parameters such as initial concentration of waste gas, total flow rate, relative humidity and voltage was investigated. The results show that the degradation rate of ethyl acetate increases with the increase of output voltage. When other conditions remain unchanged, the degradation rate decreases with the increase of initial concentration of ethyl acetate; with the increase of total flow rate, the degradation rate of ethyl acetate decreases; with the increase of relative humidity, the degradation rate first increases and then decreases, and when the relative humidity is 64%, the degradation efficiency is the highest.

Water-Preserved Mining Technology and Practice in Typical High Intensity Mining Area of China

( Yajun Sun ),( Zhimin Xu ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

ShenDong mining area is China's important coal production base and typical high intensity mining field, which is also a typical fragile ecological environment of arid and semi-arid areas. High intensity mining area coal production and ecological environment coordinated development is an important research topic in the area. High intensity in coal mining production and coordinated development of ecological environment is an important research topic in the area. Aiming at the lack of water resources in arid and semi-arid, fragile ecological environment in Shendong mining area, this paper puts forward the partition of hydrogeological structure and the water-preserved mining by studying the structure characteristics of hydrological geology, coal strata structure type, etc. On this basis, according to different hydrogeological structure type, it puts forward the the basic principles of water preserving mining in ShenDong mining area and key technology of water-preserved mining such as coal mining important water source area in mining area, thick bedrock aquifer, burning rocks aquifer, water transfer storage and use of mine water resources. Finally, combining with the typical mine, it carries out the key technology of the engineering practice and achieves good application effect. The paper’s research result has a certain guiding significance to guide the arid and semi-arid area of west China in protective exploitation of water resources.