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Magnetic alignment of MnBi crystals and magnetic properties of MnBi-Bi composites
Yongsheng Liu,Jincang Zhang,Zhongming Ren,Shixun Cao,Xiaoyong Zhang,Guangqiang Jia,Kang Deng,Xi Li,Junxi Zhang 한국물리학회 2007 Current Applied Physics Vol.7 No.5
Below Curie temperatureTC, MnBi crystals are aligned alongc-axis in a Bi matrix under a fabrication eldHfof 0.5 T. AboveTC,this alignment is also accomplished by quenching under a highHfof 10 T. Such a method has a prominent feature that MnBi crystalsgrow preferentially and congregate along theHfdirection. Magnetic testing shows a pronounced anisotropy in magnetization in direc-tions normal and parallel toHf, resulting from the alignment. In the case of the alignment belowTC,Hfincreases the transition temper-ature of spin-reorientation and the change in magnetization.
Youhua Li,Lubing Shi,Zhongming Liu,Xiaopeng Wang,Xuetao Qiao,Zhihong Zhang,Shidang Yan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
For high-speed, heavy-load gear units, the meshing tooth surfaces are generally under the mixed lubrication state, which is crucial for gear pitting or micro pitting damage. To clarify the effects of lubrication state on tooth pitting damage, carrying out both numerical and experimental studies on the contact severity of gears under different lubrication states is necessary. In this paper, a 3D line-contact elasto hydrodynamic lubrication model considering fractal surface roughness was developed and used to investigate the lubrication characteristics of involute gears. Both the distributions of pressure and film thickness fluctuated under the rolling contact of rough surfaces. The fluctuations became more substantial with the increase of load and roughness. Furthermore, from the calculated film thickness ratio λ, the contact of gear tooth surfaces with a fractal roughness of Ra = 0.8 μm was always under full lubrication state (λ > 1). When the roughness was increased to Ra = 3.2 μm, the contact was first transmitted into the mixed lubrication state (0.2 < λ < 1) under the load of 1000 N*m and finally deteriorated to boundary lubrication state (λ < 0.2) under the load of 2000 N*m. The boundary lubrication state that occurred under the contact of highly rough surfaces could induce the formation of gear pitting damage. The contact fatigue test showed the gear tooth surface roughness increased from 0.7 μm to around 2.7 μm after 8 million running cycles and then suffered pitting failure after another 2 million cycles, which was consistent with the simulation analysis prediction.
Lee, Byeongyong,Lee, Chongmin,Liu, Tianyuan,Eom, Kwangsup,Chen, Zhongming,Noda, Suguru,Fuller, Thomas F.,Jang, Hee Dong,Lee, Seung Woo Royal Society of Chemistry 2016 Nanoscale Vol.8 No.24
<P>Crumpled graphene is known to have a strong aggregation-resistive property due to its unique 3D morphology, providing a promising solution to prevent the restacking issue of graphene based electrode materials. Here, we demonstrate the utilization of redox-active oxygen functional groups on the partially reduced crumpled graphene oxide (r-CGO) for electrochemical energy storage applications. To effectively utilize the surface redox reactions of the functional groups, hierarchical networks of electrodes including r-CGO and functionalized few-walled carbon nanotubes (f-FWNTs) are assembled via a vacuum-filtration process, resulting in a 3D porous structure. These composite electrodes are employed as positive electrodes in Li-cells, delivering high gravimetric capacities of up to similar to 170 mA h g(-1) with significantly enhanced rate-capability compared to the electrodes consisting of conventional 2D reduced graphene oxide and f-FWNTs. These results highlight the importance of microstructure design coupled with oxygen chemistry control, to maximize the surface redox reactions on functionalized graphene based electrodes.</P>
Minmin Yu,Huihui Zhang,Zhongming Liu,Zhao Ge,Fangong Kong,Huili Shao,Xuechao Hu 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8
The regenerated cellulose fiber (Lyocell) and natural cellulose fiber (ramie) with different initial lengths were usedto reinforce polylactide (PLA) by melt compounding and injection molding. The fiber dimension and its distribution incomposites after injection molding were analyzed by high-resolution Fiber Quality Analyzer (FQA). Moreover, the contentsof small fibers with length < 0.2 mm were also provided by FQA. Then the influences of fiber dimension and its distributionon the mechanical properties of the composites were investigated. The results showed that fiber length was reduced duringcompounding and injection molding processes, and the longer the initial fiber length, the more severe the length declined. Compared with ramie fiber, Lyocell fiber showed a longer fiber length, smaller diameter and narrower width distribution incomposite after injection molding. Additionally, the content of small fiber played an important role in the analysis of therelation between the fiber dimension and mechanical properties of composites owing to its smaller aspect ratio. The differentmechanical characteristics of the PLA composites were attributed predominantly to the fiber aspect ratio and the small fibercontent. By comparison, Lyocell fiber exhibited better reinforcement for PLA due to the higher aspect ratio and lower smallfiber content. The tensile strength, tensile modulus and impact strength of Lyocell/PLA composite were increased by 8.61 %,75.43 % and 26.9 %, respectively.
Mohamad Abdalkader,Stephanos Finitsis,Chuanhui Li,c Wei Hu,Xinfeng Liu,Xunming Ji,Xiaochuan Huo,Fana Alemseged,Zhongming Qiu,Daniel Strbian,Volker Puetz,James E. Siegler,Shadi Yaghi,Kaiz Asif,Piers Kl 대한뇌졸중학회 2023 Journal of stroke Vol.25 No.1
Background and Purpose The optimal management of patients with acute basilar artery occlusion (BAO) is uncertain. We aimed to evaluate the safety and efficacy of endovascular thrombectomy (EVT) compared to medical management (MM) for acute BAO through a meta-analysis of randomized controlled trials (RCTs). Methods We performed a systematic review and meta-analysis of RCTs of patients with acute BAO. We analyzed the pooled effect of EVT compared to MM on the primary outcome (modified Rankin Scale [mRS] of 0–3 at 3 months), secondary outcome (mRS 0–2 at 3 months), symptomatic intracranial hemorrhage (sICH), and 3-month mortality rates. For each study, effect sizes were computed as odds ratios (ORs) with random effects and Mantel-Haenszel weighting. Results Four RCTs met inclusion criteria including 988 patients. There were higher odds of mRS of 0-3 at 90 days in the EVT versus MM group (45.1% vs. 29.1%, OR 1.99, 95% confidence interval [CI] 1.04–3.80; P=0.04). Patients receiving EVT had a higher sICH compared to MM (5.4% vs. 0.8%, OR 7.89, 95% CI 4.10–15.19; P<0.01). Mortality was lower in the EVT group (35.5% vs. 45.1%, OR 0.64, 95% CI 0.42–0.99; P=0.05). In an analysis of two trials with BAO patients and National Institutes of Health Stroke Scale (NIHSS) <10, there was no difference in 90-day outcomes between EVT versus MM. Conclusion In this systematic review and meta-analysis, EVT was associated with favorable outcome and decreased mortality in patients with BAO up to 24 hours from stroke symptoms compared to MM. The treatment effect in BAO patients with NIHSS <10 was less certain. Further studies are of interest to evaluate the efficacy of EVT in basilar occlusion patients with milder symptoms.