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| 1 | Effect of heat treatment on the microstructure and mechanical properties of AZ80M magnesium alloy fabricated by wire arc additive manufacturing显示文摘To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated.Three different heat treatment procedures(T4,T5 and T6)were performed.According to the results,after T4 heat treatment,the microsegregation of alloying elements was improved with the eutectic structure dissolved.Samples after T5 heat treatment inherited the net-like distribution of secondary phases similar to the as-deposited sample,where the eutectic structure covering the interdendritic regions and theβ-phase precipitated around the eutectic structure.After T6 heat treatment,the tinyβ-phases re-precipitated from the matrix and distributed in inner and outer of the grains.The hardness distribution of the samples went through T4 and T6 heat treatment was more uniform in comparison to that of T5 heat treated samples.The tensile test showed that the T6 heat treatment improved the strength and ductility,and the anisotropy between horizontal and vertical can be eliminated.Moreover,T4 treated samples exhibited highest ductility. | Yangyang Guo Gaofeng Quan Mert Celikin Lingbao Ren Yuhang Zhan Lingling Fan Houhong Pan | 2022 | Journal of Magnesium and Alloys2022，10，7： | 5 |
| 2 | Analysis on nasal airway by using scale-adaptive simulation combined with standard κ-ω model and 3D printing modeling physical experiment显示文摘The physiological structure of the upper respiratory tract is complex and varies with each individual,and the circulating air has turbulent performance.In this paper,based on computed tomography(CT)medical images published online and the three-dimensional(3D)printing technology,a 3D model of the human upper respiratory tract was reconstructed and an experimental device of the upper respiratory tract was made.We implemented the respiratory experiment and measured the flow rate,and a scale-adaptive κ-ω model is applied for numerical simulation,the results are in good agreement.The flow field during respiratory was analyzed by coronal velocity cross section,vortex line and particle tracks.We found that the relatively strong shear effect happens at the areas of nasal valve and nasopharynx.In the middle and upper nasal tract,vortex line separation occurs and there is significant passage effect.The results indicate that SAS method is effective in studying upper respiratory airflow. | Jiemin Zhan Yangyang Xi Kay Lin Weiguang Yu Wenqing Hu | 2019 | Theoretical & Applied Mechanics Letters2019，9，4： | 1 |
| 3 | Metabolic engineering of Bacillus amyloliquefaciens for efficient production ofα-glucosidase inhibitor1-deoxynojirimycin显示文摘Owing to the feature of strongα-glucosidase inhibitory activity,1-deoxynojirimycin(1-DNJ)has broad application prospects in areas of functional food,biomedicine,etc.,and this research wants to construct an efficient strain for 1-DNJ production,basing on Bacillus amyloliquefaciens HZ-12.Firstly,using the temperature-sensitive shuttle plasmid T2(2)-Ori,gene ptsG in phosphotransferase system(PTS)was weakened by homologous recombination,and non-PTS pathway was strengthened by deleting its repressor gene iolR,and 1-DNJ yield of resultant strain HZ-S2 was increased by 4.27-fold,reached 110.72 mg/L.Then,to increase precursor fructose-6-phosphate(F-6-P)supply,phosphofructokinase was weaken,fructose phosphatase GlpX and 6-phosphate glucose isomerase Pgi were strengthened by promoter replacement,moreover,regulator gene nanR was deleted,1-DNJ yield was further increased to 267.37 mg/L by 2.41-fold.Subsequently,promoter of 1-DNJ synthetase cluster was optimized,as well as 5′-UTRs of downstream genes in synthetase cluster,and 1-DNJ produced by the final strain reached 478.62 mg/L.Last but not the least,1-DNJ yield of 1632.50 mg/L was attained in 3 L fermenter,which was the highest yield of 1-DNJ reported to date.Taken together,our results demonstrated that metabolic engineering was an effective strategy for 1-DNJ synthesis,this research laid a foundation for industrialization of functional food and drugs based on 1-DNJ. | Xujie Li Meng Zhang Yu Lu Ningyang Wu Jian’gang Chen Zhixia Ji Yangyang Zhan Xin Ma Junyong Chen Dongbo Cai Shouwen Chen | 2023 | Synthetic and Systems Biotechnology2023，8，3： | 0 |
| 4 | Microbial synthesis of bacitracin:Recent progress,challenges,and prospects显示文摘Microorganisms are important sources of various natural products that have been commercialized for human medicine and animal healthcare.Bacitracin is an important antibacterial natural product predominantly pro-duced by Bacillus licheniformis and Bacillus subtilis,and it is characterized by a broad antimicrobial spectrum,strong activity and low resistance,thus bacitracin is extensively applied in animal feed and veterinary medicine industries.In recent years,various strategies have been proposed to improve bacitracin production.Herein,we systematically describe the regulation of bacitracin biosynthesis in genus Bacillus and its associated mechanism,to provide a theoretical basis for bacitracin overproduction.The metabolic engineering strategies applied for bacitracin production are explored,including improving substrate utilization,using an enlarged precursor amino acid pool,increasing ATP supply and NADPH generation,and engineering transcription regulators.We also present several approaches of fermentation process optimization to facilitate the industrial large-scale production of bacitracin.Finally,the challenges and prospects associated with microbial bacitracin synthesis are discussed to facilitate the establishment of high-yield and low-cost biological factories. | Jiang Zhu Shiyi Wang Cheng Wang Zhi Wang Gan Luo Junhui Li Yangyang Zhan Dongbo Cai Shouwen Chen | 2023 | Synthetic and Systems Biotechnology2023，8，2： | 0 |
| 5 | Application of Simple Head Cooling Combined with Gangliosides in Neonatal Hypoxic-ischemic Encephalopathy显示文摘Objective To investigate the effect of simple head cooling combined with ganglioside therapy on neonatal hypoxic-ischemic encephalopathy(HIE)and its clinical efficacy.Methods A total of 100 children with HIE admitted in the neonatal ward of our hospital from August 2018 to October 2020 were selected as the research objects,and were divided into control group and observation group according to the random number table method,with 50 cases in each group.The control group was treated with gangliosides,and the observation group was treated with simple head cooling combined with gangliosides.Observe and compare the clinical performance improvement time,the level of relevant hematological examination indexes before and after treatment,and the neonatal behavioral neurological assessment(NBNA),clinical efficacy,and adverse reactions.Results The improvement time of convulsions,disturbance of consciousness,pupil changes,hypotonia,and gastrointestinal dysfunction in the observation group was significantly lower than that in the control group(all P<0.001).After treatment,the NSE,IL-6,CK,CK-MB of the two groups of children were significantly lower than before treatment,and the serum calcium and NBNA scores were significantly higher than before treatment,and the decrease or increase in the observation group was significantly higher than that of the control Group(all P<0.001).The total effective rate of treatment of children in the observation group(82.00%)was higher than that of the control group(62.00%)(P<0.05).There were no obvious adverse reactions in both groups.Conclusion The simple head cooling combined with gangliosides in the treatment of HIE can improve the clinical symptoms,blood test index levels,and NBNA scores.The clinical effect is clear and superior to the single use of gangliosides. | Zhen Zhan Huanhuan Cheng Xianhong Lin Yangyang Meng Liying Dai Hong Zheng Qilian Xie | 2020 | Journal of Human Physiology2020，2，2： | 0 |
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