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Zhang, Shi-Hong,Cho, Tong-Yul,Yoon, Jae-Hong,Li, Ming-Xi,Shum, P.W.,Kwon, Sik-Chol Elsevier 2009 Materials science and engineering B. Advanced Func Vol.162 No.2
<P><B>Abstract</B></P><P>Laser heat (LH) treatment was found to be an effective method to alter the microstructure and mechanical properties of conventional coatings. In this investigation, the effects of laser scanning velocity on microstructure, microhardness and wear performance of high velocity oxygen fuel sprayed (HVOF) WC–CrC–Ni coatings during laser heating treatment were investigated. The results showed that the microstructure of the HVOF coatings changed greatly after the LH treatment. X-ray diffraction (XRD) patterns indicated that WC and Cr<SUB>3</SUB>C<SUB>2</SUB>, as primary phases, were present in both the HVOF- and LH-treated coatings, while only a small amount of Ni phase existed in the LH-treated coatings. With the post-treatment process of laser heating, a compact interface was found between the coating and substrate. When the laser scanning velocity decreased, the porosity and thickness of the LH-treated coatings decreased, leading to a gradual increase of microhardness. In the wear test, the friction and wear resistance of the coating were improved significantly with an optimal laser heating process (600W power, 300mm/min scanning velocity). The improvement can be attributed to the improved porosity and hardness, as well as the formation of oxide tribofilms.</P>
Anomalous magnetization jumps in granular Pb superconducting films
Zhang An-Lei,Jiang Wan-Yan,Chen Xing-Hong,Zhang Xiao-Ke,Lu Wen-Lai,Chen Fei,Feng Zhen-Jie,Cao Shi-Xun,Zhang Jin-Cang,Ge Jun-Yi 한국물리학회 2022 Current Applied Physics Vol.35 No.-
In granular superconductors, the grain boundaries are closely related to the vortex dynamics and the macroscopic superconducting properties. In our research, Pb films with different grain sizes were prepared by tuning the substrate temperature. With the grain size decreasing, Pb films are prone to feature the anomalous magnetization jumps in the M − T curves, while in the M − H curves flux avalanche happens. Both phenomena appear in the same region of the H − T phase diagram and thus are considered to have the same origin. The further theoretical analysis shows that with grain size decreasing the pinning mechanism evolves from a mixed δTc and δl pinning to the δl pinning mechanism. The results shed light on the study of pinning mechanism for granular superconductors and is beneficial to the potential application of manipulating vortex pinning by regulation of intrinsic defects.
Evaluation of Nanocrystalline TiN Films Prepared by Arc Ion Plating
Shi Hong Zhang,천희곤,조동율,윤재홍,주윤곤,조재영 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.6
Monolayer and multilayer TiN films were synthesized on a SKD 11 steel sheet by an arc ion plating technique and the correlation between the microstructure and properties of the TiN films was comparatively investigated. The results indicated that the main phase was fcc-TiN, showing a (200) preferred orientation in the film under 2.0 × 10 -1 torr N2 partial pressure, whereas a gradual transition to (111) preferred orientation was observed with decreasing N2 partial pressure to 1.4 × 10 -1 torr. The (200) and (111) textures in the film under an arc current of 80 A were found to be competitive orientations, but the (200) texture became stronger as the arc current was increased. Compared to the optimal monolayer TiN films, the multilayer TiN film possessed high hardness of up to 20.3 ± 1.3 GPa and excellent wear resistance. These features are attributed to the presence of dense microstructures that are mainly composed of TiN phase and are around 1.7 μm to 1.8 μm in thickness.
Hong Zhang, Shi,Xi Li, Ming,Hong Yoon, Jae,Yul Cho, Tong,Zhu He, Yi,Gyu Lee, Chan Elsevier 2008 SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS Vol.9 No.3
<P>Micron-size Ni-base alloy (NBA) powders were mixed with both 1.5 wt.% (hereinafter %) micron-size CeO<SUB>2</SUB> (<I>m</I>-CeO<SUB>2</SUB>) and also 1.5% and 3.0% nano-size CeO<SUB>2</SUB> (<I>n</I>- CeO<SUB>2</SUB>) powders. These mixtures were coated on low-carbon steel (Q235) by 2.0 kW CO<SUB>2</SUB> laser cladding. The effects on the microstructures, phases and electrochemical corrosion of the coatings upon the addition of <I>m</I>- and <I>n</I>- CeO<SUB>2</SUB> powders to NBA (<I>m</I>- and <I>n</I>- CeO<SUB>2</SUB> /NBA) have been investigated. The results showed that a smooth coating was prepared under suitable processing parameters (<I>P</I>= 2.0 kW, <I>V</I>= 180 mm min<SUP>- 1</SUP>) by adding 1.5% <I>n</I>- CeO<SUB>2</SUB>. In addition to the primary phases of γ-Ni, Cr<SUB>23</SUB> C<SUB>6</SUB> and Ni<SUB>3</SUB> B in the Ni-base alloy coating, CeNi<SUB>3</SUB> was formed in Ni-base alloy coatings with both <I>n</I>- CeO<SUB>2</SUB> and <I>m</I>-CeO<SUB>2</SUB> particles, and CeNi<SUB>5</SUB> appeared in the coating upon decreasing the size of CeO<SUB>2</SUB> particles. Well-developed dendrites were observed in the Ni-base alloy coating; directional dendrites grew at the interface in the coating upon the addition of <I>m</I>-CeO<SUB>2</SUB>, whereas fine and multioriented dendrites grew upon decreasing the size of CeO<SUB>2</SUB> particles to the nanoscale. Actinomorphic dendrites and compact equiaxed dendrites grew from the interface to near the surface upon increasing the content of <I>n</I>- CeO<SUB>2</SUB> from 1.5 to 3.0%. In strongly acidic HNO<SUB>3</SUB> solution, the severe corrosion of dendrites occurred and there were many corrosion pits in the Ni-base alloy coating; intercrystalline corrosion also has a dominant role upon the addition of <I>m</I>-CeO<SUB>2</SUB>, whereas uniform corrosion occurs in the coating as the size of CeO<SUB>2</SUB> particles is decreased to nanoscale.</P>
Linghao Zhang,Lu Zhang,Chun-Hong Zhang,Xiao-Bi Fang,Zhen-Xiao Huang,Qing -Yuan Shi,Li-Ping Wu,Peng Wu,Zhen-Zhen Wang,Zhi-Su Liao 대한이비인후과학회 2016 Clinical and Experimental Otorhinolaryngology Vol.9 No.4
Objectives. Chronic rhinosinusitis (CRS) is common disease in otorhinolaryngology and will lead to lower airway abnormality. However, the only lung function in CRS patients and associated factors have not been much studied. Methods. One hundred patients with CRS with nasal polyps (CRSwNP group), 40 patients with CRS without nasal polyps (CRSsNP group), and 100 patients without CRS were enrolled. The difference in lung function was compared. Meanwhile, CRSwNP and CRSsNP group were required to undergo a bronchial provocation or dilation test. Additionally, subjective and objective outcomes were measured by the visual analogue scale (VAS), 20-item Sino-Nasal Outcome Test (SNOT-20), Lund-Mackay score, Lund-Kennedy endoscopic score. The correlation and regression methods were used to analyze the relationship between their lung function and the above parameters. Results. The forced expiratory volume in 1 second (FEV1) and forced expiratory flow between 25% and 75% of forced vital capacity (FEF25-75) of CRSwNP group were significantly lower than other groups (P<0.05). On peak expiratory flow, there was no difference between three groups. In CRSwNP group, FEV1 was negatively correlated with peripheral blood eosinophil count (PBEC) and duration of disease (r=–0.348, P=0.013 and r=–0.344, P=0.014, respectively), FEF25-75 negatively with VAS, SNOT-20 (r=–0.490, P=0.028 and r=–0.478, P=0.033, respectively) in CRSsNP group. The incidence of positive bronchial provocation and dilation test was lower in CRSwNP group (10% and 0%, respectively), with both 0% in CRSsNP group. The multiple linear regression analysis indicated that change ratio of FEV1 before and after bronchial provocation or dilation test were correlated with PBEC in CRSwNP group (β=0.403, P=0.006). Conclusion. CRS leading to impaired maximum ventilation and small airway is associated with the existence of nasal polyp. Lung function impairments can be reflected by PBEC, duration, VAS, and SNOT-20. In CRSwNP patients, PBEC is independent predictor of FEV1 change ratio.
Wang Lu,Dai Ying-Jie,Cui Yu,Zhang Hong,Jiang Chang-Hao,Duan Ying-Jie,Zhao Yong,Feng Ye-Fang,Geng Shi-Mei,Zhang Zai-Hui,Lu Jiang,Zhang Ping,Zhao Li-Wei,Zhao Hang,Ma Yu-Tong,Song Cheng-Guang,Zhang Yi,Ch 대한뇌졸중학회 2023 Journal of stroke Vol.25 No.3
Background and Purpose Intravenous tenecteplase (TNK) efficacy has not been well demonstrated in acute ischemic stroke (AIS) beyond 4.5 hours after onset. This study aimed to determine the effect of intravenous TNK for AIS within 4.5 to 24 hours of onset. Methods In this pilot trial, eligible AIS patients with diffusion-weighted imaging (DWI)-fluid attenuated inversion recovery (FLAIR) mismatch were randomly allocated to intravenous TNK (0.25 mg/kg) or standard care within 4.5–24 hours of onset. The primary endpoint was excellent functional outcome at 90 days (modified Rankin Scale [mRS] score of 0–1). The primary safety endpoint was symptomatic intracranial hemorrhage (sICH). Results Of the randomly assigned 80 patients, the primary endpoint occurred in 52.5% (21/40) of TNK group and 50.0% (20/40) of control group, with no significant difference (unadjusted odds ratio, 1.11; 95% confidence interval 0.46–2.66; <i>P</i>=0.82). More early neurological improvement occurred in TNK group than in control group (11 vs. 3, <i>P</i>=0.03), but no significant differences were found in other secondary endpoints, such as mRS 0–2 at 90 days, shift analysis of mRS at 90 days, and change in National Institutes of Health Stroke Scale score at 24 hours and 7 days. There were no cases of sICH in this trial; however, asymptomatic intracranial hemorrhage occurred in 3 of the 40 patients (7.5%) in the TNK group. Conclusion This phase 2, randomized, multicenter study suggests that intravenous TNK within 4.5–24 hours of onset may be safe and feasible in AIS patients with a DWI-FLAIR mismatch.