Biologically Inspired Engineering of Self-assembling and Multi-functional Underwater Adhesives

Chao ZHONG 한국생물공학회 2015 한국생물공학회 학술대회 Vol.2015 No.4

Design of Multifunctional Degradable Polymeric Nanosystems for Active Tumor-Targeting Drug Delivery

Yinan Zhong,Ru Cheng,Chao Deng,Fenghua Meng,Jian Zhang,Zhiyuan Zhong 한국고분자학회 2014 한국고분자학회 학술대회 연구논문 초록집 Vol.2014 No.10

Disruption of ecdysis in Leptinotarsa decemlineata by knockdown of chitin deacetylase 1

Jian-Jian Wu,Li-Li Mu,Zhong-Chao Chen,Kai-Yun Fu,Wen-Chao Guo,Chao Li,Guo-Qing Li 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.2

Chitin deacetylases (CDAs) catalyze N-deacetylation of chitin, a crucial process for chitin modification. In the present paper, LdCDA1 was identified in Leptinotarsa decemlineata. It was copiously expressed in larval foregut, hindgut and epidermis. Just before the molt in the first, second and third larval instars, the mRNA levels of LdCDA1 were high. In the fourth (final)-instar larvae, a peak occurred 4 days after ecdysis. In vivo results revealed that LdCDA1 transcriptionally responded, positively and negatively respectively, to 20-hydroxyecdysone and juvenile hormone titers. Moreover, knockdown of LdCDA1 significantly reduced foliage consumption, lengthened developing period and prevented growth in the final instar larvae. Three distinct lethal phenotypes were noted in the LdCDA1 RNAi larvae. About 30% of the RNAi larvae became moribund and finally died; approximately 50% of deformed pupae died as pharate adults; and around 20% of LdCDA1 depleted pupae finally emerged as abnormal adults and eventually died within 1 week after emergence. Furthermore, chitin content was low and the mRNA levels of five chitin biosynthesis transcripts (LdUAP1, LdUAP2, LdChSAa, LdChSAb and LdChSB) were significantly declined in the LdCDA1 RNAi larvae. In addition, glucose, trehalose and glycogen contents were increased in the LdCDA1 depleted hypomorphs, along with highly expressed genes coding for trehalose and glycogen synthesis enzymes. The findings provide a compelling piece of evidence that CDA1 is critical for chitin deposition in L. decemlineata. Moreover, LdCDA1 may be a potential target for control of the larvae.

Comparative Study of Two Common In Vitro Models for the Pancreatic Islet with MIN6

Chao Xinxin,Zhao Furong,Hu Jiawei,Yu Yanrong,Xie Renjian,Zhong Jianing,Huang Miao,Zeng Tai,Yang Hui,Luo Dan,Peng Weijie 한국조직공학과 재생의학회 2023 조직공학과 재생의학 Vol.20 No.1

BACKGROUND: Islet transplantation is currently considered the most promising method for treating insulin-dependent diabetes. The two most-studied artificial islets are alginate-encapsulated b cells or b cell spheroids. As three-dimensional (3D) models, both artificial islets have better insulin secretory functions and transplantation efficiencies than cells in twodimensional (2D) monolayer culture. However, the effects of these two methods have not been compared yet. Therefore, in this study, cells from the mouse islet b cell line Min6 were constructed as scaffold-free spheroids or alginate-encapsulated dispersed cells. METHODS: MIN6 cell spheroids were prepared by using Agarose-base microwell arrays. The insulin secretion level was determined by mouse insulin ELISA kit, and the gene and protein expression status of the MIN6 were performed by Quantitative polymerase chain reaction and immunoblot, respectively. RESULTS: Both 3D cultures effectively promoted the proliferation and glucose-stimulated insulin release (GSIS) of MIN6 cells compared to 2D adherent cells. Furthermore, 1% alginate-encapsulated MIN6 cells demonstrated more significant effects than the spheroids. In general, three pancreatic genes were expressed at higher levels in response to the 3D culture than to the 2D culture, and pancreatic/duodenal homeobox-1 (PDX1) expression was higher in the cells encapsulated in 1% alginate than that in the spheroids. A western blot analysis showed that 1% alginate-encapsulated MIN6 cells activated the phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (AKT)/forkhead transcription factor FKHR (FoxO1) pathway more than the spheroids, 0.5% alginate-, or 2% alginate-encapsulated cells did. The 3D MIN6 culture, therefore, showed improved effects compared to the 2D culture, and the 1% alginate-encapsulated MIN6 cells exhibited better effects than the spheroids. The upregulation of PDX1 expression through the activation of the PI3K/AKT/FoxO1 pathway may mediate the improved cell proliferation and GSIS in 1% alginate-encapsulated MIN6 cells. CONCLUSION: This study may contribute to the construction of in vitro culture systems for pancreatic islets to meet clinical requirements.

A Multi-scale Segmentation Method of Oil Spills in SAR Images Based on JSEG and Spectral Clustering

Chao Wang,Li-Zhong Xu,Xin Wang,Feng-Chen Huang 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.1

LIOUVILLE THEOREMS OF SLOW DIFFUSION DIFFERENTIAL INEQUALITIES WITH VARIABLE COEFFICIENTS IN CONE

ZHONG BO FANG,CHAO FU,LINJIE ZHANG 한국산업응용수학회 2011 Journal of the Korean Society for Industrial and A Vol.15 No.1

We here investigate the Liouville type theorems of slow diffusion differential inequality and its coupled system with variable coefficients in cone. First, we give the definition of global weak solution, and then we establish the universal estimate ( does not depend on the initial value ) of solution by constructing test function. At last, we obtain the nonexistence of non-negative non-trivial global weak solution within the appropriate critical exponent. The main feature of this method is that we need not use comparison theorem or the maximum principle.

Feasibility study of buckling-restrained braces with PM-35 steel core

Chao Zhao,Qianqian Chen,Xingu Zhong,Tianyu Zhang,Zhiwen Chen 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.2

The energy dissipation characteristics of core materials greatly influence the working performance of bucklingrestrained braces (BRBs), so it is a vital work to develop more excellent energy dissipation core materials. In this research, a series of experimental studies are conducted, including the mechanical properties of PM-35 steels and the working performance of PM-35 BRB specimens, which serve to investigate the feasibility of PM-35 steel as core materials of BRBs. In addition, the analysis of variance (ANOVA) has been conducted to study the sensitivity factors of energy dissipation of PM-35 BRB specimens, especially the pre-force applied on the BRB specimens. According to the results of this research, it can be concluded that the energy absorption efficiency of PM-35 BRBs specimens is much higher than that of BRB specimens with ordinary core materials; the internal pores greatly weaken the yield strength of PM-35 steel and obviously improve the plastic deformation capacity, which makes that PM-35 core materials are able to absorb energy in a lower stress level; pre-force applied on core materials is the key factor governing the energy absorption, and can significantly improve the working performance of BRB specimens with PM-35 core materials.

Research on Fracture of Aluminum Foil in Microscale Laser Peen Forming

Chao Zheng,Sheng Sun,Jing Liu,Zhong Ji 한국소성가공학회 2010 기타자료 Vol.2010 No.6

A novel numerical method for dynamic fracture in microscale laser peen forming (μLPF) of aluminum foils was presented and the role of the die diameter on fracture behavior at the ultra high strain rate was investigated via both experimental and numerical methods. μLPF is a process in which the plastic deformation is generated through laserinduced shock wave and compressive residual stresses can be imparted to improve the fatigue life of micro parts. During μLPF, the pressure exerted on the target is higher than 1 GPa and the strain rate is greater than 10? s<SUP>-1</SUP>, so the mechanical behavior of materials in this dynamic process is very different from that under static or quasi-static conditions. In the present study, the finite element method with grain and grain boundary elements was used to analyze the μLPF process of aluminum foils with a thickness of 60 μm. The onset and propagation of crack were simulated in this way that the specified nodes were tied together until the equivalent plastic strain exceeded a certain value. Under a given value of plastic strain, the influence of die diameters of 0.6, 1.0, and 1.6 mm on the fracture mode of the material was predicted. A series of experiments were carried out to verify the numerical model. The geometrical morphologies of fracture regions were observed via optical microscope and scan electron microscope. In results from both experiments and simulations, the size of the die diameter affects the location of the fracture: (I) Fracture appeared at the entrance of the die for die diameters of 0.6 and 1.0 mm. (II) Fracture occurred near the centre of the formed dome for 1.6 mm die diameter. The generation mechanism of two fracture modes was explained. This work provides a preliminary insight into the fracture behavior of materials under the ultra high strain rate and lays the ground work for more in-depth simulations in the future study.

A modified RBSM for simulating the failure process of RC structures

Chao Zhao,Xingu Zhong,Bo Liu,Xiaojuan Shu,Mingyan Shen 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.2

In this paper, a modified rigid body spring model (RBSM) is proposed and used to analyze the damage and failure process of reinforced concrete (RC) structures. In the proposed model, the concrete is represented by an assembly of rigid blocks connected with a uniform distribution of normal and tangential springs to simulate the macroscopic mechanical behavior of concrete. Steel bars are evenly dispersed into rigid blocks as a kind of homogeneous axial material, and an additional uniform distribution of axial and dowel springs is defined to consider the axial stiffness and dowel action of steel bars. Perfect bond between the concrete and steel bars is assumed, and tension stiffening effect of steel bars is modeled by adjusting the constitutive relationship for the tensile reinforcement. Adjacent blocks are allowed to separate at the contact interface, which makes it convenient and easy to simulate the cracking process of concrete. The failure of the springs is determined by the Mohr-Coulomb type criterion with the tension and compression caps. The effectiveness of the proposed method is confirmed by elastic analyses of a cantilever beam under different loading conditions and failure analyses of a RC beam under two-point loading.

Study on the constitutive behavior and hot deformation characteristic of Mg-4Sm-2Zn-0.5Zr alloy

Zhong-Yi Cai,Chao-jie Che,Ruo-Han Chang,Li-Ren Cheng,Qing-Min Chen 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.3

Mg–4Sm–2Zn–0.5Zr alloy is a new type of heat-resistant magnesium alloy, it has the mechanical properties similar to EZ33 alloy but is much cheaper than EZ33 in cost since Samarium (Sm) rather than Nd was employed in the alloy. In this paper, based on isothermal compression tests in the temperature range of 350–450 °C and strain rate range of 0.001–1.0 s−1, the Arrhenius-type constitutive equations for this alloy were established, and the hot working flow behavior and the microstructures of the alloy were examined. To evaluate the hot deformation mechanisms and determine the optimal processing parameters, 3D processing maps under different deformation conditions were developed according to the dynamic material model and Muthy instability criterion. The hot extrusion experiments were carried out, and the results show the predictions of processing maps are in agreement with the experimental results.