Machining Surface Quality Analysis of Aluminum Alloy Thin-Walled Parts in Aerospace

Dai Bing,Yu Guang-bin,Guan Yan-qi,Shao Jun-peng,Guan Yan-qi,Wu Xue-mei,Liu Yu-xin 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.11

There are many key parts in the field of aerospace with aluminum alloy thin-walled parts, the problem of breaking the low efficiency in production that’s also followed. There will be a lot of deformation in processing because of its poor rigidity, poor process, which will lead to low processing efficiency. It is of great significance to improve the machining efficiency of the aluminum alloy thin-walled parts, and a series of analysis of the surface quality of aluminum alloy thin-walled parts there are carried out clamping, cutting tools, take the knife route so on, and the problems of low machining efficiency and poor surface quality are solved.

Experimental and Numerical Study on the Damage Evolution Behaviour of Granitic Rock during Loading and Unloading

Dai Bing,Zhao Guoyan,H. Konietzky,P. L. P. Wasantha 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.9

Theoretical and experimental studies have revealed that the damage evolution plays an important role in stability of rock structures. To investigate the damage characteristics of rocks during loading and unloading, a series of conventional triaxial tests and numerical simulations were conducted on granitic rock specimens under different confining pressures. The stress-strain characteristics and fracture patterns of tested specimens were first analyzed. It was found that the failure strain in unloading is smaller than the failure strain in loading. And the difference between the two strains is growing with increasing confining pressure. The failure patterns of specimens displayed two different failure mechanisms: a single distinct failure and a “X” failure. Based on the law of energy conservation, the energy evolution was analyzed. The results indicated that absorbed strain energy converted into elastic strain energy and dissipation energy. For evaluating and predicting damage, two damage degrees were proposed considering increase of dissipation energy and decrease of tangential modulus, respectively. The results show that before the reversal point of volumetric strain, the damage degrees were almost unchanged. During the process of unloading the damage degrees increases fast. For the same strain, lower confining pressure shows more damage. It indicates that the confining pressure has negative effects on increase of the damage degree. Then, the discrete element model based on elastic and unbreakable voronoi blocks was set-up for tri-axial tests. The energy evolution and damage process were simulated. And the ratio of failed contacts was used to simulate the damage degree. It shows that stress-strain behavior as well as micro- and macro-mechanical damage evolution can be reproduced by the DEM model.

Special Transmission Gear Invalidation Analysis Coupled with Finite Element Method Based on Meshless Local Petrov-Galerkin Method

Bing Dai,J. P Shao,Xuemei Wu,Guangbin Yu,Ye Song,Ge Jianghua 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.10

Aiming at high nonlinear problem of special transmission gear invalidation analysis, provided a method which based on Meshless local Petrov-Galerkin method coupled with finite element method and method to solve fracture problem of special transmission gear. Simulation calculation has been done to non-involute beveloid gear developed by project team. Calculation result verified efficiency of the simulation method. The method has important meaning to novel gear development and research.

Study of compensatory growth based on different nutrition conditions of Bombyx mori

Dai Minli,Feng Piao,Mao Tingting,Gu Haoyi,Bian Dandan,Sun Haina,Li Fanchi,Wei Jing,Li Bing 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.3

Organisms achieve compensatory growth after a period of nutrient restriction followed by recovering the nutrient status. However, the underlying mechanisms associated with such growth acceleration remain unclear. The silkworm Bombyx mori is a lepidopteran model insect. This study aimed to investigate the physiological characteristics and the underlying mechanisms in B. mori fed on mulberry leaves (MG), artificial diet (AG), and artificial diet + mulberry leaves (AG-MG), respectively. Silkworms in AG-MG which fed on artificial diet from 1st to 3rd instars followed by feeding on mulberry leaves from 4th to 5th instars exhibited a higher weight gain rate than that in MG and AG, indicating that compensatory growth occurred as a result of the switch in the silkworm food regime. Trypsin and lipase activities of silkworms in AG-MG were shown to be up-regulated at 72 h after changing food. Digital gene expression profiling (DGE) analysis revealed that genes related to metabolism and development in silkworm midguts were differentially expressed. The quantitative real-time PCR (qRT-PCR) re sults showed that the expression levels of IIS/PI3K-AKT pathway genes including INR, IRS, AKT, PI3K60 and PI3K110 of silkworms in AG were down-regulated compared with that in MG at 0 h. Whereas AKT, PI3K and PI3K60 of silkworms were significantly increased by 1.68-, 1.49-, 1.67-fold, respectively, at 72 h after switched to mulberry leaves than the same instar fed on artificial diet. PDK’s expression of silkworms in AG was higher than that in other two groups at each timepoint. Compared with MG and AG, PTEN and IRS were down-regulated at 48 and 72 h in AG-MG. Collectively, these results indicate that compensatory growth in B. mori is regulated by IIS/ PI3K-AKT signaling pathway.

Systemic administration of low dosage of tetanus toxin decreases cell proliferation and neuroblast differentiation in the mouse hippocampal dentate gyrus

Bing Chun Yan,In Hye Kim,Joon Ha Park,Ji Hyeon Ahn,Jeong-Hwi Cho,Bai Hui Chen,Jae-Chul Lee,Jung Hoon Choi,Ki-Yeon Yoo,Choong Hyun Lee,Jun Hwi Cho,Jong-Dai Kim,Moo-Ho Won 한국실험동물학회 2013 Laboratory Animal Research Vol.29 No.3

In the present study, we investigated the effect of Tetaus toxin (TeT) on cell proliferation and neuroblast differentiation using specific markers: 5-bromo-2-deoxyuridine (BrdU) as an exogenous marker for cell proliferation, Ki-67 as an endogenous marker for cell proliferation and doublecortin (DCX) as a marker for neuroblasts in the mouse hippocampal dentate gyrus (DG) after TeT treatment. Mice were intraperitoneally administered 2.5 and 10 ng/kg TeT and sacrificed 15 days after the treatment. In both the TeT-treated groups, no neuronal death occurred in any layers of the DG using neuronal nuclei (NeuN, a neuron nuclei maker) and Fluoro-Jade B (F-J B, a high-affinity fluorescent marker for the localization of neuronal degeneration). In addition, no significant change in glial activation in both the 2.5 and 10 ng/kg TeT-treated-groups was found by GFAP (a marker for astrocytes) and Iba-1 (a marker for microglia) immunohistochemistry. However, in the 2.5 ng/kg TeT-treated-group, the mean number of BrdU, Ki-67 and DCX immunoreactive cells, respectively, were apparently decreased compared to the control group, and the mean number of each in the 10 ng/kg TeT-treated-group was much more decreased. In addition, processes of DCX-immunoreactive cells, which projected into the molecular layer, were short compared to those in the control group. In brief, our present results show that low dosage (10 ng/kg) TeT treatment apparently decreased cell proliferation and neuroblast differentiation in the mouse hippocampal DG without distinct gliosis as well as any loss of adult neurons.

Comparison of trophic factors changes in the hippocampal CA1 region between the young and adult gerbil induced by transient cerebral ischemia.

Yan, Bing Chun,Park, Joon Ha,Kim, Sung Koo,Choi, Jung Hoon,Lee, Choong Hyun,Yoo, Ki-Yeon,Kwon, Young-Geun,Kim, Young-Myeong,Kim, Jong-Dai,Won, Moo-Ho Kluwer Academic/Plenum Publishers 2012 Cellular and molecular neurobiology Vol.32 No.8

<P>In the present study, we investigated neuronal death/damage in the gerbil hippocampal CA1 region (CA1) and compared changes in some trophic factors, such as brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF), in the CA1 between the adult and young gerbils after 5 min of transient cerebral ischemia. Most of pyramidal neurons (89%) were damaged 4 days after ischemia-reperfusion (I-R) in the adult; however, in the young, about 59% of pyramidal neurons were damaged 7 days after I-R. The immunoreactivity and levels of BDNF and VEGF, not GDNF, in the CA1 of the normal young were lower than those in the normal adult. Four days after I-R in the adult group, the immunoreactivity and levels of BDNF and VEGF were distinctively decreased, and the immunoreactivity and level of GDNF were increased. However, in the young group, all of their immunoreactivities and levels were much higher than those in the normal young group. From 7 days after I-R, all the immunoreactivities and levels were apparently decreased compared to those of the normal adult and young. In brief, we confirmed our recent finding: more delayed and less neuronal death occurred in the young following I-R, and we newly found that the immunoreactivities of trophic factors, such as BDNF, GDNF, and VEGF, in the stratum pyramidale of the CA1 in the young gerbil were much higher than those in the adult gerbil 4 days after transient cerebral ischemia.</P>

Selective blockade of spinal D2DR by levocorydalmine attenuates morphine tolerance via suppressing PI3K/Akt-MAPK signaling in a MOR-dependent manner

Wen-Ling Dai,Xin-Tong Liu,Yi-Ni Bao,Bing Yan,Nan Jiang,Bo-Yang Yu,Ji-Hua Liu 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

Morphine tolerance remains a challenge in the management of chronic pain in the clinic. As shown in our previous study, the dopamine D2 receptor (D2DR) expressed in spinal cord neurons might be involved in morphine tolerance, but the underlying mechanisms remain to be elucidated. In the present study, selective spinal D2DR blockade attenuated morphine tolerance in mice by inhibiting phosphatidylinositol 3 kinase (PI3K)/serine–threonine kinase (Akt)-mitogen activated protein kinase (MAPK) signaling in a μ opioid receptor (MOR)-dependent manner. Levocorydalmine (l-CDL), which exhibited micromolar affinity for D2DR in D2/CHO-K1 cell lines in this report and effectively alleviated bone cancer pain in our previous study, attenuated morphine tolerance in rats with chronic bone cancer pain at nonanalgesic doses. Furthermore, the intrathecal administration of l-CDL obviously attenuated morphine tolerance, and the effect was reversed by a D2DR agonist in mice. Spinal D2DR inhibition and l-CDL also inhibited tolerance induced by the MOR agonist DAMGO. l-CDL and a D2DR small interfering RNA (siRNA) decreased the increase in levels of phosphorylated Akt and MAPK in the spinal cord; these changes were abolished by a PI3K inhibitor. In addition, the activated Akt and MAPK proteins in mice exhibiting morphine tolerance were inhibited by a MOR antagonist. Intrathecal administration of a PI3K inhibitor also attenuated DAMGO-induced tolerance. Based on these results, l-CDL antagonized spinal D2DR to attenuate morphine tolerance by inhibiting PI3K/Akt-dependent MAPK phosphorylation through MOR. These findings provide insights into a more versatile treatment for morphine tolerance.

Effect of Collagen Scaffold with Adipose-derived Stromal Vascular Fraction Cells on Diabetic Wound Healing: A Study in a Diabetic Porcine Model

Yanan Jiang,Bing Chen,Yongbo Liu,Zhongyin Zhufu,Xin Yan,Xianglin Hou,Jianwu Dai,Qian Tan 한국조직공학과 재생의학회 2013 조직공학과 재생의학 Vol.10 No.4

Diabetes can impair neovascularization important for wound healing, and this study investigated the hypothesis that this effect can be reversed by an active provisional matrix. Here, a 3D collagen scaffold and uncultured adipose-derived SVFs were firstly utilized to construct a collagen-targeting system for wound healing in a diabetic porcine model. The diabetic porcine models were made by injected streptozocin (STZ) intravenously and removed full thickness skin from the dorsum. Each animal received four different samples: Group A (control groups, n=24), Group B (SVFs groups, n=24), Group C (scaffold groups, n=24), Group D (SVFs -scaffold groups, n=24). PBS was applied to the wounds in Group A. 1×105 SVFs suspended in PBS were sprayed on the wounds in Group B. Scaffolds only with PBS were covered on the wounds in Group C. Scaffolds with equal volume of cell suspension containing 1×105 SVFs were covered on the wounds in Group D. The healing rates were calculated and compared among the groups and the tissues of the wound were taken and evaluated for histological analysis. The diabetic wound treated with the SVFs -collagen scaffold showed a significant decrease in wound size, an increase of neovascularization and a maximum VEGF and bFGF expression in comparison with SVFs and scaffold alone. The SVFs-collagen scaffold accelerates wound healing since it stimulates higher capillary formation causes major proangiogenesis factors expression in diabetic pigs suffering from skin defects, suggesting this approach could have utility for diabetic wound healing.

Accuracy and reproducibility of 3D digital tooth preparations made by gypsum materials of various colors

Tan, Fa-Bing,Wang, Chao,Dai, Hong-Wei,Fan, Yu-Bo,Song, Jin-Lin The Korean Academy of Prosthodonitics 2018 The Journal of Advanced Prosthodontics Vol.10 No.1

PURPOSE. The study aimed to identify the accuracy and reproducibility of preparations made by gypsum materials of various colors using quantitative and semi-quantitative three-dimensional (3D) approach. MATERIALS AND METHODS. A titanium maxillary first molar preparation was created as reference dataset (REF). Silicone impressions were duplicated from REF and randomized into 6 groups (n=8). Gypsum preparations were formed and grouped according to the color of gypsum materials, and light-scanned to obtain prepared datasets (PRE). Then, in terms of accuracy, PRE were superimposed on REF using the best-fit-algorithm and PRE underwent intragroup pairwise best-fit alignment for assessing reproducibility. Root mean square deviation (RMSD) and degrees of similarity (DS) were computed and analyzed with SPSS 20.0 statistical software (${\alpha}=.05$). RESULTS. In terms of accuracy, PREs in 3D directions were increased in the 6 color groups (from 19.38 to $20.88{\mu}m$), of which the marginal and internal variations ranged $51.36-58.26{\mu}m$ and $18.33-20.04{\mu}m$, respectively. On the other hand, RMSD value and DS-scores did not show significant differences among groups. Regarding reproducibility, both RMSD and DS-scores showed statistically significant differences among groups, while RMSD values of the 6 color groups were less than $5{\mu}m$, of which blue color group was the smallest ($3.27{\pm}0.24{\mu}m$) and white color group was the largest ($4.24{\pm}0.36{\mu}m$). These results were consistent with the DS data. CONCLUSION. The 3D volume of the PREs was predisposed towards an increase during digitalization, which was unaffected by gypsum color. Furthermore, the reproducibility of digitalizing scanning differed negligibly among different gypsum colors, especially in comparison to clinically observed discrepancies.

Effect of different tooth preparation designs on the marginal and internal fit discrepancies of cobalt-chromium crowns produced by computer-aided designing and selective laser melting processes

Na Yu,Hong-Wei Dai,Fa-Bing Tan,Jin-Lin Song,Chao-Yi Ma,Xue-Lu Tong 대한치과보철학회 2021 The Journal of Advanced Prosthodontics Vol.13 No.5

PURPOSE. To evaluate the impact of five different tooth preparation designs on the marginal and internal fit discrepancies of cobalt-chromium (CoCr) crowns produced by computer-aided designing (CAD) and selective laser melting (SLM) processes. MATERIALS AND METHODS. Five preparation data were constructed, after which design crowns were obtained. Actual crowns were fabricated using an SLM process. After the data of actual crowns were obtained with structural light scanning, intaglio surfaces of the design crown and actual crown were virtually superimposed on the preparation. The fit-discrepancies were displayed with colors, while the root means square was calculated and analyzed with one-way analysis of variance (ANOVA), Tukey’s test or Kruskal-Wallis test (α = .05). RESULTS. The marginal or internal color-coded images in the five design groups were not identical. The shoulder-lip and sharp line angle groups in the CAD or SLM process had larger marginal or internal fit discrepancies compared to other groups (P < .05). In the CAD process, the mean marginal and internal fit discrepancies were 10.0 to 24.2 μm and 29.6 to 31.4 μm, respectively. After the CAD and SLM processes, the mean marginal and internal fit discrepancies were 18.4 to 40.9 μm and 39.1 to 47.1 μm, respectively. The SLM process itself resulted in a positive increase of the marginal (6.0 - 16.7 μm) and internal (9.0 - 15.7 μm) fit discrepancies. CONCLUSION. The CAD and SLM processes affected the fit of CoCr crowns and varied based on the preparation designs. Typically, the shoulder-lip and sharp line angle designs had a more significant effect on crown fit. However, the differences between the design groups were relatively small, especially when compared to fit discrepancies observed clinically.