Fabrication and Interface Structural Behavior of Mg/Al Thickness-Oriented Bonding Sheet via Direct Extrusion

Lei Gao,Feng Li,Ye Wang,Xing Mao Xiao,Peng Da Huo 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

Solid-state bonding of heterogeneous materials is one of the effective ways to achieve light weight. An extrusion formingprocess for Mg/Al thickness-oriented bonding sheet was carried out. Due to triaxial compressive stress in the extrusion container,the AZ31 and AA6061 billets were deformed and the bonding and forming of Mg/Al thickness-oriented sheet can berealized by this method. The observation results of the bonding position by using XRD, SEM and EDS showed that: at theforming temperature with 360–420 °C, it had a good bonding interface, and the width of the transition layer increased withthe increase of the forming temperature. The presence of brittle intermetallic compounds in the transition layer indicated thatmetallurgical bonding had occurred at the interface. Considering all factors comprehensively, when the forming temperaturewas 390 °C, the bonding quality was appropriate. Its tensile-shear strength was 42 MPa, the width of the interface transitionlayer was about 10 μm, and the microhardness was about 164.3 HV. This method provided scientific guidance and technicalreserves for green forming of Mg/Al sheets.

Study on Multi-Field Coupled Evolution Mechanism of Laser Irradiated 40Cr Steel Quenching Process Based on Phase Change Induced Plasticity

Chang Li,Hexin Gao,Xinxue Chen,Zhaotai Liu,Xing Han 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

40Cr is essential to steel for the manufacture of hardened gears, and optimizing its laser quenching process will be of greatsignificance for gear wear and life extension. However, the complete reliance on the experimental trial-and-error approachdoes not effectively reveal the mechanism of the evolution of the laser quenching process in disk laser. Numerical simulationprovides an effective way to obtain the transient evolution of the laser quenching process. In this paper, the temperaturechanges physical parameters of the quenched material are calculated based on the CALPHAD method. Establish a thermoelastic–plastic multi-field coupling model for the laser hardening process of the disk laser 40Cr gear steel. Perform thenumerical calculations on the transient temperature, martensite phase fraction, and the transformation-induced plasticitystress evolution of the 40Cr laser hardening process. Focus on the mechanism of the mutual coupling between phase changebehavior and plastic strain. Calculations show that there is heat accumulation during quenching, with a peak temperatureof 1448 K. Plastic stress has a “hump” distribution, with a peak value of 834 MPa, which is 1.25 mm from the center ofthe focal point. The experimental analyses of the 40Cr gear steel quenching microstructure and hardness distribution stateby the Axioskop2 scanning electron microscope, the KEYENCE VH-Z100R super depth of field 3D microscope, and theQ10M microhardness tester reveal the mechanical behavior of the material and the phase hardening law during the quenchingprocess. That provided an essential theoretical basis for effective prediction on quenching residual stress and optimizingindustrial production parameters.

Development of ligustrazine-loaded lipid emulsion: Formulation optimizatiom, characterization and biodistribution

( Lijun Wei ),( Nirmal Marasini ),( Gao Li ),( Chul Soon Yong ),( Jong Oh Kim ),( Qizhe Quan ) 영남대학교 약품개발연구소 2013 영남대학교 약품개발연구소 연구업적집 Vol.23 No.0

Ligustrazine is a traditional Chinese medicine used to treat various cardiovascular and neurovascular complications. However, this compound exhibits rapid first-pass metabolism, a short biological half-life, low stability and potential vascular irritation that restrict its use for long-term therapy. The use of a lipid emulsion as a carrier for intravenous administration of ligustrazine might provide sustained and prolonged release, thereby reducing the frequency of administration and improving patient compliance. The main purpose of our study was to develop a highly stable and sterile optimal formulation of a ligustrazine lipid emulsion (LLE) and to evaluate its pharmacokinetic behavior and tissue distribution in rats. The final optimal formulation consisted of soybean oil (12.0%), oleic acid (0.6%), lecithin (1.0%), poloxamer 188 (0.6%) and glycerol (2.25%). The average particle size, polydispersity index (PDI), zeta-potential and pH of the final product were 215.0±2.5 nm, 0.076±0.033, -40.4±5.3 mV and 7.25±0.05, respectively. The LLE was stable for at least three months at room temperature. In vitro drug release studies of the LLE suggested a sustained release profile, which was further confirmed by in vivo pharmacokinetic studies in rats. The area under the drug concentration-time curve from 0 h to 10 h (AUC(0-10h)) for LLE was increased by 1.6-fold compared with that of the commercially available ligustrazine injection (LI), suggesting enhanced bioavailability from the lipid-based emulsion. Furthermore, a tissue distribution study showed significant improvement in the distribution pattern of ligustrazine with a higher AUC(0-180 min) observed in all tissues for LLE than for LI. In conclusion, LLE, with excellent stability, improved pharmacokinetics and tissue distribution, demonstrates great potential for the delivery of ligustrazine for clinical applications.ⓒ2012 Elsevier B.V.All rights reserved.

Characterization, Luminescence, and Defect Centers of a Ce3+-Doped Li2Si2O5 Phosphor Prepared by a Solution Combustion Reaction

Singh, Vijay,Watanabe, S.,Gundu Rao, T. K.,Senthil Kumaran, R.,Gao, Hui,Li, Jinglin,Kwak, Ho-Young Springer-Verlag 2015 Journal of electronic materials Vol.44 No.8

Biochar-supported nZVI (nZVI/BC) for contaminant removal from soil and water: A critical review

Wang, Shengsen,Zhao, Mingyue,Zhou, Min,Li, Yuncong C.,Wang, Jun,Gao, Bin,Sato, Shinjiro,Feng, Ke,Yin, Weiqin,Igalavithana, Avanthi Deshani,Oleszczuk, Patryk,Wang, Xiaozhi,Ok, Yong Sik Elsevier 2019 Journal of hazardous materials Vol.373 No.-

<P><B>Abstract</B></P> <P>The promising characteristics of nanoscale zero-valent iron (nZVI) have not been fully exploited owing to intrinsic limitations. Carbon-enriched biochar (BC) has been widely used to overcome the limitations of nZVI and improve its reaction with environmental pollutants. This work reviews the preparation of nZVI/BC nanocomposites; the effects of BC as a supporting matrix on the nZVI crystallite size, dispersion, and oxidation and electron transfer capacity; and its interaction mechanisms with contaminants. The literature review suggests that the properties and preparation conditions of BC (e.g., pore structure, functional groups, feedstock composition, and pyrogenic temperature) play important roles in the manipulation of nZVI properties. This review discusses the interactions of nZVI/BC composites with heavy metals, nitrates, and organic compounds in soil and water. Overall, BC contributes to the removal of contaminants because it can attenuate contaminants on the surface of nZVI/BC; it also enhances electron transfer from nZVI to target contaminants owing to its good electrical conductivity and improves the crystallite size and dispersion of nZVI. This review is intended to provide insights into methods of optimizing nZVI/BC synthesis and maximizing the efficiency of nZVI in environmental cleanup.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Aggregation and passivation of nZVI can be alleviated by surfactants and doping methods. </LI> <LI> BC hinders corrosion and improves the dispersion and electron transfer of nZVI. </LI> <LI> Properties of nZVI depend on those of the BC, feedstock and pyrogenic temperature. </LI> <LI> BC enhances electron transfer from nZVI to the contaminants due to the presence of quinone and graphene moieties. </LI> <LI> nZVI/BC shows strong ability to remove HMs, nitrates, and organic contaminants in soil and water. </LI> </UL> </P>

The effect of spin reorientation transition of antiferromagnetic NiO on the Py magnetic anisotropy in Py/NiO/CoO/MgO(0 0 1)

Yang, M.,Li, Q.,N'Diaye, A.T.,Dong, Q.Y.,Gao, N.,Arenholz, E.,Hwang, C.,Wu, Y.Z.,Qiu, Z.Q. Elsevier 2018 Journal of magnetism and magnetic materials Vol.460 No.-

<P><B>Abstract</B></P> <P>Using X-ray Magnetic Linear Dichroism (XMLD) measurement, we investigate the antiferromagnetic (AFM) NiO spin reorientation transition (SRT) in epitaxial NiO/CoO/MgO(0 0 1) system at room temperature and constructed a complete NiO spin phase diagram. Then utilizing Magneto-Optic Kerr Effect (MOKE) combined with a rotation magnetic field (ROTMOKE), we investigated the effect of NiO SRT on the magnetic anisotropy of a ferromagnetic (FM) Py overlayer in Py/NiO/CoO/MgO(0 0 1) system. We find that the Py coercivity and anisotropy only slightly enhanced for Py on top of out-of-plane NiO spins but greatly enhanced for Py on top of in-plane NiO spins. Both the uniaxial and fourfold anisotropies of the Py showed a clear dependence on the NiO spin orientation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spin reorientation transition (SRT) of antiferromagnetic NiO. </LI> <LI> Direct measurement of antiferromagnetic spins using XMLD. </LI> <LI> Quantitative determination of Py magnetic anisotropy using ROTMOKE. </LI> <LI> Demonstration of the effect of the NiO SRT on the Py magnetic anisotropy. </LI> </UL> </P>

Persistent free radicals in carbon-based materials on transformation of refractory organic contaminants (ROCs) in water: A critical review

Qin, Yaxin,Li, Guiying,Gao, Yanpeng,Zhang, Lizhi,Ok, Yong Sik,An, Taicheng Elsevier 2018 Water research Vol.137 No.-

<P><B>Abstract</B></P> <P>With the increased concentrations and kinds of refractory organic contaminants (ROCs) in aquatic environments, many previous reviews systematically summarized the applications of carbon-based materials in the adsorption and catalytic degradation of ROCs for their economically viable and environmentally friendly behavior. Interestingly, recent studies indicated that carbon-based materials in natural environment can also mediate the transformation of ROCs directly or indirectly due to their abundant persistent free radicals (PFRs). Understanding the formation mechanisms of PFRs in carbo-based materials and their interactions with ROCs is essential to develop their further applications in environment remediation. However, there is no comprehensive review so far about the direct and indirect removal of ROCs mediated by PFRs in amorphous, porous and crystalline carbon-based materials. The review aims to evaluate the formation mechanisms of PFRs in carbon-based materials synthesized through pyrolysis and hydrothermal carbonization processes. The influence of synthesis conditions (temperature and time) and carbon sources on the types as well as the concentrations of PFRs in carbon-based materials are also discussed. In particular, the effects of metals on the concentrations and types of PFRs in carbon-based materials are highlighted because they are considered as the catalysts for the formation of PFRs. The formation mechanisms of reactive species and the further transformation mechanisms of ROCs are briefly summarized, and the surface properties of carbon-based materials including surface area, types and number of functional groups, etc. are found to be the key parameters controlling their activities. However, due to diversity and complexity of carbon-based materials, the exact relationships between the activities of carbon-based materials and PFRs are still uncertain. Finally, the existing problems and current challenges for the ROCs transformation with carbon-based materials are also pointed out.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Abundant of PFRs formed in carbon-based materials during the synthesis process. </LI> <LI> The PFRs types and concentrations affected by synthesis conditions. </LI> <LI> The PFRs can activate oxidants and reductants to degrade organic contaminants. </LI> <LI> The PFRs can directly react with organic contaminants. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of Ru crystal phase on the catalytic activity of hydrolytic dehydrogenation of ammonia borane

Chen, Guozhu,Wang, Ruyue,Zhao, Wei,Kang, Baotao,Gao, Daowei,Li, Cuncheng,Lee, Jin Yong Elsevier 2018 Journal of Power Sources Vol.396 No.-

<P><B>Abstract</B></P> <P>Ruthenium (Ru) is one of the most attractive catalysts in the hydrolytic dehygrogenation of ammonia borane. So far, the employed Ru-based catalysts are mainly focusing on hexagonal close packed structured Ru. In this work, we study the crystal phase effect of Ru on the hydrolytic dehygrogenation of ammonia borane, using face-centered cubic structured and hexagonal close packed structured Ru nanoparticles supported on γ-Al<SUB>2</SUB>O<SUB>3</SUB>. The results show that the catalytic activity is different even these two kinds of Ru nanoparticles hold similar size. Impressively, with the Ru particle size change, the variation trend of activity is opposite for face-centered cubic and hexagonal close packed structured Ru/γ-Al<SUB>2</SUB>O<SUB>3</SUB>. Finally, some possible reasons for their difference are proposed based on density functional theory calculations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The crystal phase effect of Ru on the hydrolysis of ammonia borane was studied. </LI> <LI> The <I>hcp</I> Ru/γ-Al<SUB>2</SUB>O<SUB>3</SUB> exhibits higher activity than that of <I>fcc</I> Ru with similar Ru size. </LI> <LI> The variation trend of activity is opposite with the <I>fcc</I> and <I>hcp</I> Ru size change. </LI> <LI> DFT was used to understand the activity difference between <I>fcc</I> and <I>hcp</I> Ru. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Two-dimensional metal organic framework for effective gas absorption

Cheng, Kaiwu,Li, Yaojia,Gao, Zhiguo,Chen, Fanghui,You, Chaoqun,Sun, Baiwang Elsevier 2019 Inorganic Chemistry Communications Vol.101 No.-

<P><B>Abstract</B></P> <P>Herein, crystalline metal organic framework (MOF) nanosheets have been fabricated through using a modified soft physical exfoliation method from bulk crystals of a layered MOF, [Cd(4,4′‑bpy)<SUB>2</SUB>(H<SUB>2</SUB>O)<SUB>2</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB>·(2,4′‑bpy)<SUB>2</SUB>·H<SUB>2</SUB>O (MOF-1), and fully characterized via transmission electron microscope (TEM), scanning electron microscopy (SEM), and atomic force microscope (AFM). The delaminated MOF-1 nanosheets with porous structure showed good growth potential in selective gas adsorption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Using a modified soft physical exfoliation method from bulk crystals, we firstly synthesized a layered MOF nanosheets. </LI> <LI> The MOF-2 nanosheets revealed a superior absorption performance. </LI> <LI> The delaminated MOF nanosheets with porous structure showed good growth potential in selective gas adsorption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Thermal Stability of Precipitates in Al-2.8wt%Cu-1.4wt%Li Alloy

Congcong Zhu,Guoai Li,Shijia Hao,Guoling Mao,Wenli Gao 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

The microstructures and mechanical properties of Al-2.8 wt%Cu-1.4 wt%Li-T87 alloy after thermal exposure at 125, 150and 175 °C were measured and characterized by universal testing machine, scanning electron microscope and transmissionelectron microscope. The thermal stability of microstructures and mechanical properties of T87 heat-treated Al-2.8 wt%Cu-1.4 wt%Li alloy was investigated. The results show that the tensile strength of Al-2.8 wt%Cu-1.4 wt%Li-T87 alloy increasedfirst and then decreased with the increase of thermal exposure temperature, which is due to the change of the number and sizeof precipitates. After thermal exposure at 125 °C, the alloy exhibited higher strength due to further precipitation of θ′ phaseand stable size of T1phase. After thermal exposure at 175 °C, the mechanical properties of Al-2.8 wt%Cu-1.4 wt%Li-T87alloy decreased obviously, which was related to the dissolution of θ' phase and thickening of T1phase.