Sulphonated Reduced Graphene Oxide: A High Performance Anode Material for Lithium Ion Battery

Haibo Li,Rui Niu,Sen Liang,Yulong Ma,Min Luo,Jin Li,Lijun He 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4

In this work, the sulfonated reduced graphene oxide (SRGO) was synthesized and proposed as an enhanced anode material for lithium ion battery (LIB). The result shows that the SRGO has an improved battery performance (i.e., ~341.7 mAh/g and ~190.6 mAh/g corresponds to SRGO and RGO at the 100th cycle with a current density of 200 mA/g) and superior cycling stability compared with pristine reduced graphene oxide (RGO). These are attributed to the improved specific surface area (448.35 m2 /g) and conductivity (2.5 x 10-4 S/m). Further, the SRGO exhibits good rate capability and excellent energy density at various current densities ranging from 50 mAh/g to 2000 mAh/g, suggesting that SRGO could be a promising anode material for high capacity LIB.

Synthesis and characterization of a K/K2CO3-based solid superbase as a catalyst in propylene dimerization

Haibo Jin,Heng Jiang,Qiwei Wang,Suohe Yang,Guohua Luo,Guangxiang He 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

A novel solid superbase 3%K/K2CO3 was prepared by loading metallic potassium on K2CO3. The optimized preparation conditions included a loading time of 1.5 h, loading temperature of 150 oC, loading amount of 3wt% and average carrier size of 120 μm. Under the optimum conditions, the conversion of propylene is about 60% with the selectivity of dimers 98.5% and the selectivity of 4MP1 86.3%. In addition, the superbase 3%K/K2CO3 has a base strength of H−≥37, and the concentration of basic sites of H−≥35 is approximately 0.3mmol·g−1 CAT. The microcrystal of metallic potassium was determined using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was assumed that the oxygen species, which are adjacent to lattice defects, such as the crystalline corners, edges and vacancies of metallic potassium microcrystals, constituted the superbasic sites.

A New Method of Gelatin Modified Collagen and Viscoelastic Study of Gelatin-Collagen Composite Hydrogel

Lang He,Sheng Li,Chengzhi Xu,Benmei Wei,Juntao Zhang,Yuling Xu,Beirong Zhu,Yang Cao,Xilin Wu,Zhijin Xiong,Rongrui Huang,Jian Yang,Haibo Wang 한국고분자학회 2020 Macromolecular Research Vol.28 No.9

Pure collagen materials are expensive with poor mechanical properties, which need modifications in most cases. As the degradation product of collagen, gelatin is cheap, degradable and biocompatible, but few literatures have reported the research about gelatin-collagen composite materials. This is because gelatin and collagen have different soluble temperatures—gelatin is soluble in hot water (≥30 oC) and swells in cold water. However, a low temperature (2-10 oC) is required to prepare and store collagen solution, and neutral collagen solution denatures quickly above the room temperature. In this study, gelatin was ground into powders and swelled in neutral bovine tendon pepsin-soluble collagen solution (BPSC) to form a homogeneous gelatin-collagen mixture, in light of the swelling characteristics of gelatin in cold water. The assembly properties and gel properties of this composite material were further studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) test results showed that the bovine tendon collagen had typical type-I collagen structural characterizations with two α chains of about 100 kDa and one β chain of about 200 kDa; while the SDS-PAGE pattern of gelatin displayed bands continuously distributed from 30 to 200 kDa. Amino acid composition analysis test indicated that the content of polar amino acids and the sum of acidic and base amino acids for gelatin were higher than that of BPSC. Studies on gel properties demonstrated that gelatin-collagen mixed solution had collagenlike assembly characteristics and assembly kinetics. The moduli of the assembled gel at 35 oC were equivalent to that of pure bovine tendon collagen system; moreover, the system moduli didn’t change with time with elastic moduli (G') of about 40 Pa. However, at 25 oC, the moduli of gelatin-collagen composite hydrogel increased with the extension of time, its G' increased about 18 times within 8 h, and the ratio of elastic modulus to viscous modulus (G'') increased 4.6 times, showing a significant aging effect of structural strength. Meanwhile, the mechanical strength of the composite hydrogel was also regulated by temperature—the gel was highly elastic (G'≈3,000 Pa, G'>>G'') at a low temperature (5 oC); as the temperature rose, the system moduli gradually decreased and the elastic gel transformed into waterlike fluid at 50 oC little by little. What’s more, gelatin-collagen composite hydrogel also had reversible sol-gel performances and self-healing capability similar to the gelatin hydrogel. This novel preparation method for preparing composite materials and the resultant composite hydrogel are expected to be used in the fields of natural food gels, injectable hydrogels, cell scaffolds, drug sustained-release materials and so on, and improve and promote the processing performances, price and large-scale production of collagen-based materials.

Effect of Ionic Liquids on the Fibril-Formation and Gel Properties of Grass Carp (Ctenopharyngodon idellus) Skin Collagen

Zhongwei Zhai,Haibo Wang,Benmei Wei,Peiwen Yu,Chengzhi Xu,Lang He,Juntao Zhang,Yuling Xu 한국고분자학회 2018 Macromolecular Research Vol.26 No.7

Self-assembled environment of collagen is one of the important factors for improving and regulating the properties of collagen-based biomaterials. This study aimed to investigate the effect of ionic liquids (ILs) on the fibril-formation and gel properties of grass carp (Ctenopharyngodon idellus) skin collagen. Fibrillogenic kinetics analysis showed that the collagen self-assembly can be suppressed by the introduction of ILs, and the inhibitory effect is influenced by concentration and types of ILs. Scanning electron microscopy test indicated that the assembled collagen fibrils in the presence of ILs had bigger diameters than that in the conventional buffer. Differential scanning calorimetry analysis revealed that the thermal stability of collagen fibrils can be significantly increased when self-assembly is performed in the presence of ILs. Moreover, the introduction of ILs enhanced the mechanical strength of collagen gels. Finding from this work provides a new idea for improving the performance of fish-sourced collagen biomaterials.

Numerical Simulation and Analysis of Three Dimensional Flow Field of a Counter-Rotating Fan with Various Angles

Jiabin Wen,Haibo He 보안공학연구지원센터 2013 International Journal of Control and Automation Vol.6 No.6

Numerical investigations into the rubbing wear behavior of honeycomb seal

Xin Yan,Haibo Wang,Kun He 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

The rubbing wear behavior of the honeycomb land against labyrinth fin was investigated with finite-element-analysis method at a range of incursion conditions. The contact behaviors, material property, and material damage and failure are computed within the userdefined-subroutines. With the experimental data, the finite-element-analysis method was validated with respect to the frictional temperature and worn geometry. The effects of stator material, incursion depth, incursion rate and sliding velocity on the contact force, frictional temperature, material loss, and worn geometry are analyzed. The results show that the sliding velocity, final incursion depth and incursion rate are the important factors affecting the wear behaviors of honeycomb stator. The mushrooming extension is decreased with the increase of sliding velocity, and increased with the increase of incursion rate. At high sliding velocity and low incursion rate conditions, the material loss accounts more in the wear volume deformation compared to the plastic deformation.

Formation Mechanisms for (Cr,Co)7C3/(Cr,Co)23C6 Heterogeneous Precipitates and Stacking Faults Around Carbides in Surfacing Welding of Stellite Alloy on Stainless Steel

Jiankun Xiong,Haibo Zhang,Fuheng Nie,Fen He,Jianping Yang,Zhan Hu,Zhongbo Wen,Haiyan Zhao,Xinjian Yuan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The formation mechanisms for two carbides with co-existence and increasing stacking faults nearby the carbides duringsurfacing welding were investigated in this study. The results indicated that the surfacing layer had a two-phase structure ofa matrix phase and a second phase, the density of the second phase was relatively small and the second phase was discontinuous,by contrast with the as-received welding wire. Relatively uniform microstructure of surfacing layer and the weldinginterface without melting of base metal were obtained, resulting in an inapparent change in the microhardness. A few carbideswith blocky shape were identified in the surfacing layer. The mechanisms for (Cr,Co)23C6 of face-centered cubic crystalstructure co-existing with (Cr,Co)7C3 of hexagonal close-packed crystal structure and (Cr,Co)23C6 subsequently forming closeto the pre-formed (Cr,Co)7C3 during the cooling process were discussed in alloying element, calculated equilibrium phasediagram, Gibbs energy, etc. The relatively higher density of the stacking fault present around the carbides was understoodfrom forming energy of stacking faults.

Reconstituted Fibril from Heterogenic Collagens-A New Method to Regulate Properties of Collagen Gels

Jian Yang,Haibo Wang,Lang He,Benmei Wei,Chengzhi Xu,Yuling Xu,Juntao Zhang,Sheng Li 한국고분자학회 2019 Macromolecular Research Vol.27 No.11

Heterotypic collagen fibril has long been found in the tissues of organisms, which plays an important role in the formation and function of complex structures of organisms. Inspiring by the phenomenon, scholars tried to incubate collagens from different sources into novel collagen materials in vitro, and the forming of heterogenic reconstituted collagen fibrils (RF) was often demonstrated by differential scanning calorimetry (DSC) and fluorescence quenching analysis. In this work, we used two type-I collagens from different species (bovine tendon and grasscarp fish skin) to coassemble in vitro, and verified the formation of RF from a new rheological perspective. In addition, we also investigated the assembly behavior, surface hydrophilicity and hydrophobicity, microscopic morphology and cell proliferation ability of the RF. The results showed that the assembly rate, surface properties, fibril size, viscoelastic properties of RF can be delicately regulated by the method of heterogenic collagen reconstitution. This study provides new experimental evidence for the reconstitution of heterogenic collagens, and also offers a new means for the regulation of collagen gel performance, which would help to expand the application range of collagen gel materials.

How to retrieve the encrypted data on the blockchain

( Huige Li ),( Fangguo Zhang ),( Peiran Luo ),( Haibo Tian ),( Jiejie He ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.11

Searchable symmetric encryption (SSE) scheme can perform search on encrypted data directly without revealing the plain data and keywords. At present, many constructive SSE schemes were proposed. However, they cannot really resist the malicious adversary, because it (i.e., the cloud server) may delete some important data. As a result, it is very likely that the returned search results are incorrect. In order to better guarantee the integrity of outsourcing data, and ensure the correction of returned search results at the same time, in this paper, we combine SSE with blockchain (BC), and propose a SSE-on-BC framework model. We then construct two concrete schemes based on the size of the data, which can better provide privacy protection and integrity verification for data. Lastly, we present their security and performance analyses, which show that they are secure and feasible.

Microstructural Characterization and Softening Mechanism of Ultra-Low Carbon Steel and the Control Strategy in Compact Strip Production Process

Bo Jiang,Xuewen Hu,Guoning He,Huan Peng,Haibo Wang,Yazheng Liu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

In this paper, the microstructures and properties of hot rolled ultra-low carbon steel sheet produced by different compact stripproduction (CSP) processes were investigated. The softening mechanism was also discussed and the control strategy wasproposed in order to obtain optimum properties. Result showed that the average ferrite grain sizes of austenite rolling sheetand multiphase rolling sheet were 31.0 μm and 74.6 μm, respectively. The sheet after austenite rolling had a slightly higheryield and tensile strength while had a 6.3% higher elongation than that of the sheet after multiphase rolling. The higher dislocationin the sheet after multiphase rolling increased the strength while decreased the elongation. The softening mechanismof the sheet after multiphase rolling was the coarsening of ferrite grain. The combined role of {001} and {111} orientationresulted in a slight increase of the r and ̄rvalue in the sheet after multiphase rolling. It was a wise choice to conduct rollingat the Ac1temperature in CSP process to increase the grain size and decrease the dislocation density. Then, the strength ofthe sheets could be further reduced and the elongation could also be improved.