Dislocation Damping and Defect Friction Damping in Magnesium: Molecular Dynamics Study

Jingyu Zhai,Xinyuan Song,Anyang Xu,Yugang Chen,Qingkai Han 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

In this study, the molecular dynamics method was used to study the damping mechanism in Mg alloys at the atomic scale. The energy dissipated by the nucleation and motion of dislocations and by defects friction, and the effect of defects, such asvacancies, cracks, and grain boundaries, on them were studied. The study shows that different kinds of defect have differenteffects on the dislocation damping and defect friction damping. And then, the effect of strain amplitude and temperature ondamping capacity of Mg was studied. The result shows that the amplitude independent damping is caused by defect frictionand the amplitude dependent damping is mainly caused by the nucleation and motion of dislocation; the damping of Mgincreased exponentially with the temperature, and the damping peck appeared at 440 K is attributed to the appearance ofdislocations at the grain boundaries which may be caused by boundaries self-diffusion.

Numerical Simulation of Seismic Waves with Peak Arrival Time and Amplitude-Frequency Correlation

Xu Han,Zhitao Wang,Ling-yun Peng,Jingyu Su,Lihua Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

To improve the accuracy with which the non-stationary intensity characteristics of artificial acceleration-time-history curves are determined, a method of adjusting the frequency correlation between the artificial peak arrival time and amplitude spectrum is proposed. A calculation method for determining the peak arrival time to reflect the physical meaning of the phase-differenc espectrum was first deduced. Subsequently, the amplitude-distribution characteristics corresponding to the peak arrival times for different durations of natural earthquakes were analyzed. In accordance with the distribution characteristics of the reference amplitude, the frequency distribution of the artificial peak arrival time was divided into four parts: the beginning, strong-earthquake, attenuation, and tail sections. By adjusting the arrival frequency of peak points for the different earthquake durations considered, the corresponding relationship between the artificial peak arrival time and amplitude spectrum was determined to be more consistent with the general law of natural earthquakes. The sample calculation described in this paper demonstrates that adjusting the frequency correspondence between the artificial peak arrival time and amplitude spectrum greatly improves the accuracy of the non-stationary intensity characteristics of artificial acceleration-time-history curves.

Kinetic evaluation of physiological heterogeneity in bacterial spores during thermal inactivation

Xu, Hua,He, Xinlong,Gou, Jingyu,Lee, Hyeon-Yong,Ahn, Juhee The Microbiology Research Foundation 2009 The Journal of general and applied microbiology Vol.55 No.4

Application of High Pressure Processing for Extending the Shelf-life of Sliced Raw Squid

Jingyu Gou,Hua Xu,Geun-Pyo Choi,Hyeon-Yong Lee,안주희 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.4

This study was designed to evaluate the effect of high pressure processing (HPP) on the microbiological safety and quality of sliced raw squid during refrigerated storage. The sliced and vacuum-packed raw squid samples were treated at 200, 300, and 400 MPa for 20 min by using a custom-made high pressure processor. The numbers of psychrotrophic bacteria in the sliced raw squids treated at 200, 300, and 400 MPa were reduced by 0.5, 2.5, and >4.7log CFU/g, respectively. The amounts of trimethylamine (TMA) produced in the sliced raw squids were reduced by 20, 33, and 51% at 200, 300, and 400 MPa, respectively, as compared to the control. The amount of total biogenic amines (BAs) in the control significantly increased up to 1.70 mg/g after 10 days of refrigerated storage, while that in the 400 MPa-treated squid sample gradually increased up to 1.33 mg/g. The autolytic activity values in the control,200, 300, and 400 MPa-treated squid samples were 4.70,2.28, 2.18, and 1.55 nkat/g, respectively, after 20 days of refrigerated storage. The HPP effectively retarded the microbial growth, TMA formation, autolytic activity in the sliced raw squids. Therefore, the HPP could be used as an effective processing tool for improving microbiological safety and quality of seafood.

Preparation of N-Doped Nanoporous Carbon from Crude Biomass and its Electrochemical Activity

Zezhong Xu,Jingyu Si 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.3

H2O2 detection plays an important role in electrochemical sensing since H2O2 often acts as an intermediate product or regulator in various reactions. Nanoporous carbon (NPC) can be a potential candidate in electrochemical sensing because of its high specific surface area, various pore sizes and structures. In this work, we reported the preparation of N-doped NPC derived from the highly available, accessible and recyclable plant Typha orientalis. The products have high surface area (highest surface areas of 1439.0 m2 g-1) and a number of nanopores. Highest content of nitrogen atom in the product is 3.66 at.%). Typical product exhibits high electrocatalytic activity for reduction of hydrogen peroxide. The product may have further use for glucose biosensing. We developed a low-cost, simple and readily scalable approach to prepare the excellent carbon electrocatalyst directly from crude biomass. In addition, because of high surface area and doping of nitrogen element, the product may find broad applications in the fields of supercapacitors, lithium-ion batteries, gas uptake and so on.

Functional Properties of Squid By-products Fermented by Probiotic Bacteria

Hua Xu,Jingyu Gou,Geun-Pyo Choi,Hyeon-Yong Lee,Juhee Ahn 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.3

The effects of probiotic bacteria on the functional properties of squid by-products were investigated during fermentation. Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, and Pediococcus acidilactici were used to ferment the squid by-products for 96 hr at 37℃. The numbers of all probiotics increased to 10?-10? CFU/g after 96 hr fermentation. No substantial pH changes were observed. L. rhamnosus and P. acidilactici showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities. Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) secreted from B cells increased after adding the extracts of probiotic-fermented squid by-products. The human NK cells were grown well in the B cell-growing broth cultured with the extracts of squid by-products fermented by L. rhamnosus and P. acidilactici. Trimethylamine (TMA) and dimethylamine (DMA) contents were significantly decreased after probiotic-fermentation. Therefore, L. rhamnosus GG and P. acidilactici can be used for the fermentation of squid by-products and their use would provide benefits in functional food products.

Colonic Dysmotility in Murine Partial Colonic Obstruction Due to Functional Changes in Interstitial Cells

Qianqian Wang,Jingyu Zang,Xu Huang,Hongli Lu,Wenxie Xu,Jie Chen 대한소화기 기능성질환∙운동학회 2019 Journal of Neurogastroenterology and Motility (JNM Vol.25 No.4

Background/Aims Interstitial cells play important roles in gastrointestinal (GI) neuro-smooth muscle transmission. The underlying mechanisms of colonic dysmotility have not been well illustrated. We established a partial colon obstruction (PCO) mouse model to investigate the changes of interstitial cells and the correlation with colonic motility. Methods Western blot technique was employed to observe the protein expressions of Kit, platelet-derived growth factor receptor-α (Pdgfra), Ca2+-activated Cl− (Ano1) channels, and small conductance Ca2+- activated K+ (SK) channels. Colonic migrating motor complexes (CMMCs) and isometric force measurements were employed in control mice and PCO mice. Results PCO mice showed distended abdomen and feces excretion was significantly reduced. Anatomically, the colon above the obstructive silicone ring was obviously dilated. Kit and Ano1 proteins in the colonic smooth muscle layer of the PCO colons were significantly decreased, while the expression of Pdgfra and SK3 proteins were significantly increased. The effects of a nitric oxide synthase inhibitor (L-NAME) and an Ano1 channel inhibitor (NPPB) on CMMC and colonic spontaneous contractions were decreased in the proximal and distal colons of PCO mice. The SK agonist, CyPPA and antagonist, apamin in PCO mice showed more effect to the CMMCs and colonic smooth muscle contractions. Conclusions Colonic transit disorder may be due to the downregulation of the Kit and Ano1 channels and the upregulation of SK3 channels in platelet-derived growth factor receptor-α positive (PDGFRα+) cells. The imbalance between interstitial cells of Cajal-Ano1 and PDGFRα-SK3 distribution might be a potential reason for the colonic dysmotility. Background/Aims Interstitial cells play important roles in gastrointestinal (GI) neuro-smooth muscle transmission. The underlying mechanisms of colonic dysmotility have not been well illustrated. We established a partial colon obstruction (PCO) mouse model to investigate the changes of interstitial cells and the correlation with colonic motility. Methods Western blot technique was employed to observe the protein expressions of Kit, platelet-derived growth factor receptor-α (Pdgfra), Ca2+-activated Cl− (Ano1) channels, and small conductance Ca2+- activated K+ (SK) channels. Colonic migrating motor complexes (CMMCs) and isometric force measurements were employed in control mice and PCO mice. Results PCO mice showed distended abdomen and feces excretion was significantly reduced. Anatomically, the colon above the obstructive silicone ring was obviously dilated. Kit and Ano1 proteins in the colonic smooth muscle layer of the PCO colons were significantly decreased, while the expression of Pdgfra and SK3 proteins were significantly increased. The effects of a nitric oxide synthase inhibitor (L-NAME) and an Ano1 channel inhibitor (NPPB) on CMMC and colonic spontaneous contractions were decreased in the proximal and distal colons of PCO mice. The SK agonist, CyPPA and antagonist, apamin in PCO mice showed more effect to the CMMCs and colonic smooth muscle contractions. Conclusions Colonic transit disorder may be due to the downregulation of the Kit and Ano1 channels and the upregulation of SK3 channels in platelet-derived growth factor receptor-α positive (PDGFRα+) cells. The imbalance between interstitial cells of Cajal-Ano1 and PDGFRα-SK3 distribution might be a potential reason for the colonic dysmotility.

Content-Based Social Network User Interest Tag Extraction

Mei Yu,Xu Han,Xiaolu Gou,Jian Yu,Fang Lv,Jingyu Li 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.2

Colonic Transit Disorder Mediated by Downregulation of Interstitial Cells of Cajal/Anoctamin-1 in Dextran Sodium Sulfate-induced Colitis Mice

Chen Lu,Hongli Lu,Xu Huang,Shaohua Liu,Jingyu Zang,Yujia Li,Jie Chen,Wenxie Xu 대한소화기 기능성질환∙운동학회 2019 Journal of Neurogastroenterology and Motility (JNM Vol.25 No.2

Background/Aims Interstitial cells of Cajal (ICC) and their special calcium-activated chloride channel, anoctamin-1 (ANO1) play pivotal roles in regulating colonic transit. This study is designed to investigate the role of ICC and the ANO1 channel in colonic transit disorder in dextran sodium sulfate (DSS)-treated colitis mice. Methods Colonic transit experiment, colonic migrating motor complexes (CMMCs), smooth muscle spontaneous contractile experiments, intracellular electrical recordings, western blotting analysis, and quantitative polymerase chain reaction were applied in this study. Results The mRNA and protein expressions of c-KIT and ANO1 channels were significantly decreased in the colons of DSS-colitis mice. The colonic artificial fecal-pellet transit experiment in vitro was significantly delayed in DSS-colitis mice. The CMMCs and smooth muscle spontaneous contractions were significantly decreased by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), an ANO1 channel blocker, and NG-Nitro-L-arginine methyl ester hydrochloride (L-NAME), an inhibitor of nitric oxide synthase activity, in DSS-colitis mice compared with that of control mice. Intracellular electrical recordings showed that the amplitude of NPPB-induced hyperpolarization was more positive in DSS-colitis mice. The electric field stimulation-elicited nitric-dependent slow inhibitory junctional potentials were also more positive in DSS-colitis mice than those of control mice. Conclusion The results suggest that colonic transit disorder is mediated via downregulation of the nitric oxide/ICC/ANO1 signalling pathway in DSS-colitis mice.

Mechanism of Synergetic Growth of Flexibility and Strength of Biomimetic Nanocomposite Fibre

Xiangyu Duan,Pan Li,Jingyu Ouyang,Zichen Gao,Jiaxin Liu,Jie Wang,Zhigang Xia,Weilin Xu 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3

Nanocomposites with carbon nanotubes (CNTs) can combine the stiffness and multi-functionality of carbonnanotubes with the advantages of high toughness and processability of polymers giving rise to properties different from thatof general composites. However, when the content of CNTs increases gradually, the flexibility of the composite fibre canreduce. In this paper, we propose a simple method of softening the composite fibre via dimensional helical deformation offibre inner macromolecule bundles to avoid the deterioration of fibre flexibility. The theoretical simulations were conductedto predict proper helical deformations of the single fibre to increase fibre softness, followed by practical softening of thepolyvinylidene difluoride (PVDF)/CNTs composite by tensional twisting of the single fibres. The fibres with and withouttensional twisting were tested by Fourier-transformed infrared spectroscopy, scanning electron microscopy, X-ray diffractionand mechanical drawing. Results showed the reinforcement of the PVDF/multi-walled CNTs composite fibres (tensilestrength enhanced from 4.71 to 5.19 cN/dtex) with an evident softness reduction (initial modulus increased from 16.8 to20.52 cN/dtex) as the CNTs content increased from 0 to 1.5 wt%. After the tensional twisting, the initial modulus of thecomposite fibre was reduced by 62.5 % while the fibre strength remained reinforced because biomimetic helix formationimproved the internal structure deformation ability of the fibre.