Critical Quenching Rate for High Hardness and Good Exfoliation Corrosion Resistance of Al-Zn-Mg-Cu Alloy Plate

Dongfeng Li,Bangwen Yin,Yue Lei,Shengdan Liu,Yunlai Deng,Xinming Zhang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2

By means of the end-quenching technique, we investigated the relationship between quenching rate and hardness as well as exfoliation corrosion rating for Al-2.21 Zn-3.59 Mg-0.45 Cu-0.038 Zr (at%) alloy plate. In order to achieve an exfoliation corrosion rating of P or EA, the quenching rate must be greater than approximately 460 °C/min and 300 °C/min, respectively, and the drop degree in hardness should simultaneously be lower than approximately 2.0% and 3.5%, respectively. The results of microstructural and microchemical examination using a scanning transmission electron microscope indicate that a lower quenching rate leads to a higher content of Zn, Mg, and Cu in the grain-boundary particles and a greater width of precipitate-free zones near grain boundaries; therefore, grain-boundary particles with Zn and Mg contents less than approximately 13.39% and 10.23% (at%), respectively, and precipitate-free zones near grain boundaries with widths less than about 107 nm can contribute to an exfoliation corrosion rating better than EA. The amount of quench-induced η- phase particles, which lead to lower hardness, increases with decreasing quenching rate, and the area fraction of these particles is approximately 2.9% at a quenching rate of 300 °C/min.

MicroRNA expression profiles in conventional and micropropagated Dendrobium officinale

Zhili Yang,Dongfeng Yang,Xianfeng Ding,Yong Gao,Donghai Li,Tao Xu 한국유전학회 2015 Genes & Genomics Vol.37 No.4

MicroRNA (miRNA) is defined as an endogenous *22 nt noncoding RNA that has critical gene-regulatory functions in plants. Dendrobium officinale is among the most important herbs in traditional Chinese medicine. However, no miRNA of D. officinale has been reported to date. To identify the miRNA in D. officinale and to detect the differentially expressed miRNA between conventional and micropropagated D. officinale plants, miRNA microarray was performed following quantitative real-time RTPCR validation. A total of 120 miRNAs from 37 miRNA families were identified in both conventional and micropropagated D. officinale plants. Among the total number of miRNAs, 45 miRNAs from six families were differentially expressed, including five up-regulated families (miR156, miR164, miR171, miR827 and miR529) and one downregulated family (miR167) in micropropagated group. Web microrna designer and gene ontology term-enrichment analyses were applied for prediction and functional analysis of the target genes of differentially expressed miRNA. Such miRNAs are mainly related to hormone stimulus response, biological and metabolic process regulation, formation of intracellular organelle, and nucleic acid binding.

Protective Effect Against Hydroxyl Radical-induced DNA Damage and Antioxidant Mechanism of [6]-gingerol: A Chemical Study

Lin, Jing,Li, Xican,Chen, Li,Lu, Weizhao,Chen, Xianwen,Han, Lu,Chen, Dongfeng Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6

[6]-Gingerol is known as the major bioactive constituent of ginger. In the study, it was observed to effectively protect against ${\bullet}OH$-induced DNA damage ($IC_{50}$ $328.60{\pm}24.41{\mu}M$). Antioxidant assays indicated that [6]-gingerol could efficiently scavenge various free radicals, including ${\bullet}OH$ radical ($IC_{50}$ $70.39{\pm}1.23{\mu}M$), ${\bullet}O_2{^-}$ radical ($IC_{50}$ $228.40{\pm}9.20{\mu}M$), $DPPH{\bullet}$radical ($IC_{50}$ $27.35{\pm}1.44{\mu}M$), and $ABTS{^+}{\bullet}$radical ($IC_{50}$ $2.53{\pm}0.070{\mu}M$), and reduce $Cu^{2+}$ ion ($IC_{50}$ $11.97{\pm}0.68{\mu}M$). In order to investigate the possible mechanism, the reaction product of [6]-gingerol and $DPPH{\bullet}$ radical was further measured using HPLC combined mass spectrometry. The product showed a molecular ion peak at m/z 316 $[M+Na]^+$, and diagnostic fragment loss (m/z 28) for quinone. On this basis, it can be concluded that: (i) [6]-gingerol can effectively protect against ${\bullet}OH$-induced DNA damage; (ii) a possible mechanism for [6]-gingerol to protect against oxidative damage is ${\bullet}OH$ radical scavenging; (iii) [6]-gingerol scavenges ${\bullet}OH$ radical through hydrogen atom ($H{\bullet}$) transfer (HAT) and sequential electron (e) proton transfer (SEPT) mechanisms; and (iv) both mechanisms make [6]-gingerol be oxidized to semi-quinone or quinone forms.

Numerical study on failure behavior of open-hole composite laminates based on LaRC criterion and extended finite element method

Decheng Liu,Dongfeng Cao,Haixiao Hu,Yucheng Zhong,Shuxin Li 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

A new numerical model combining LaRC failure criterion and extended finite element method (XFEM) is created to describe the failure behavior in fiber-reinforced polymer (FRP) composites. In this model, the onset of intralaminar damages are predicted based on the LaRC failure criterion, and the crack propagation and stiffness degradation are described explicitly by the XFEM. The user subroutine UDMGINI of ABAQUS defines the initial damage criterion and a mixed-mode, energy-based fracture criterion is employed to describe the crack onset and propagation in the enriched region of XFEM. The proposed model is used to investigate the failure behavior of two sets of open-hole laminates under tension. It is demonstrated that the proposed numerical method can predict the experimental data well.

Non‐linear chirp based UWB waveform design for suppression of NBI

Bai, Zhiquan,Li, Xiaotong,Yuan, Dongfeng,Kwak, Kyungsup WILEY INTERSCIENCE 2012 WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Vol.12 No.6

<P><B>Abstract</B></P><P>In order to alleviate the narrowband interference (NBI) to ultra wideband (UWB) systems, we propose two non‐linear UWB chirp waveforms based on the <I>arctrigonometric</I> and <I>archyperbolic</I> function in this paper. The proposed UWB pulses can obtain good performance in NBI suppression. Both of the two chirp pulses require only the time domain processing because of the inherent relationship between the frequency domain and the time domain. Theoretical analysis and simulation results show that the direct sequence pulse binary amplitude modulation (DS‐BPAM) UWB systems with the proposed chirp waveforms can achieve excellent NBI suppression performance and outperform the linear chirp waveform based UWB system significantly. Copyright © 2010 John Wiley & Sons, Ltd.</P>

Protective Effect Against Hydroxyl Radical-induced DNA Damage and Antioxidant Mechanism of [6]-gingerol: A Chemical Study

Jing Lin,Xican Li,Li Chen,Weizhao Lu,Xianwen Chen,Lu Han,Dongfeng Chen 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.6

[6]-Gingerol is known as the major bioactive constituent of ginger. In the study, it was observed to effectively protect against •OH-induced DNA damage (IC50 328.60 ± 24.41 μM). Antioxidant assays indicated that [6]- gingerol could efficiently scavenge various free radicals, including •OH radical (IC50 70.39 ± 1.23 μM), •O2 − radical (IC50 228.40 ± 9.20 μM), DPPH• radical (IC50 27.35 ± 1.44 μM), and ABTS+• radical (IC50 2.53 ± 0.070 μM), and reduce Cu2+ ion (IC50 11.97 ± 0.68 μM). In order to investigate the possible mechanism, the reaction product of [6]-gingerol and DPPH• radical was further measured using HPLC combined mass spectrometry. The product showed a molecular ion peak at m/z 316 [M+Na]+, and diagnostic fragment loss (m/z 28) for quinone. On this basis, it can be concluded that: (i) [6]-gingerol can effectively protect against •OH-induced DNA damage; (ii) a possible mechanism for [6]-gingerol to protect against oxidative damage is •OH radical scavenging; (iii) [6]-gingerol scavenges •OH radical through hydrogen atom (H•) transfer (HAT) and sequential electron (e) proton transfer (SEPT) mechanisms; and (iv) both mechanisms make [6]-gingerol be oxidized to semi-quinone or quinone forms.

Stress and strain behavior of cementitious composites with epoxy/urea-formaldehyde microcapsules under uniaxial tests

Tielin Han,Xianfeng Wang,Dawang Li,Ningxu Han,Dongfeng Li,Feng Xing 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.S1

The effects of different dosages of microcapsules, proportion of prepressing stress and curing days on the mechanicalproperties, pore structure and healing efficiency of the specimens were studied through uniaxial compression test and mercuryintrusion porosimetry (MIP) test. The results indicate that the uniaxial strength of the specimens decreased to a certain extentwith an increase of dosage of the microcapsules. Meanwhile, the pore structure parameters (pore volume; porosity; criticalpore size; capillary porosity), as well as the self-healing rate and recovery rate of the mechanical properties increased withincreasing the dosage of microcapsules. The microcapsules have a significant influence on the deformation characteristics ofthe specimens and may improve the brittleness characteristics and strengthen the ductility of the ordinary concrete.

Association between Alanine Aminotransferase and Intracerebral Hemorrhage in East Asian Populations

Kim, Hyeon Chang,Oh, Sun Min,Pan, Wen-Harn,Ueshima, Hirotsugu,Gu, Dongfeng,Chuang, Shao-Yuan,Fujiyoshi, Akira,Li, Ying,Zhao, Liancheng,Suh, Il S. Karger AG 2013 Neuroepidemiology Vol.41 No.2

<P>Abstract</P><P><B><I>Background:</I></B> Intracerebral hemorrhage (ICH) and chronic liver disease are relatively common in East Asian countries. However, the relationship between the two diseases is unclear. Thus, we investigated the association between serum alanine aminotransferase (ALT) levels and ICH risk in East Asian populations. <B><I>Methods:</I></B> The East Asian Network for Stroke Prevention enrolled 279,982 participants with ALT measurements from four cohort studies in Korea, Taiwan, Japan and mainland China. Among them, 1,324 ICH events and 493 ICH deaths were observed. Cox's proportional hazard regression analysis was performed in each cohort to estimate the hazard ratio (HR) after adjusting for age, blood pressure, diabetes, total cholesterol, smoking and alcohol intake. Combined HRs were then estimated using pooled analyses with fixed-effects models. <B><I>Results:</I></B> The multivariate-adjusted pooled HRs (with 95% confidence interval, CI) for ICH incidence per 10 IU/l increments of ALT were 1.04 (1.03-1.04) in men and 1.01 (0.98-1.04) in women. Corresponding HRs for ICH mortality were 1.04 (1.02-1.05) in men and 1.04 (1.00-1.08) in women. The pooled HRs for ICH incidence in participants with ALT levels greater than or equal to 50 IU/l compared to those with levels less than 20 IU/l were 1.74 (1.41-2.16) in men and 1.60 (1.06-2.40) in women. The corresponding HRs for ICH mortality were 1.72 (1.21-2.44) in men and 1.63 (0.79-3.36) in women. <B><I>Conclusions:</I></B> An elevated ALT level was independently and significantly associated with an increased risk of ICH in East Asian men, but the association was less prominent in women.</P><P>© 2013 S. Karger AG, Basel</P>

Efficient treatment of anthraquinone dye wastewater by adsorption using sunflower torus-like magnesium hydroxide microspheres

Demin Jiang,Fang Wang,Bo Lan,Dacai Wang,Kezhong Liang,Tingzhen Li,Dongfeng Zhao,Jianjun Chen,Junjie Lin,Wen Chan,Yuke Li 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3

Novel sunflower torus-like magnesium hydroxide (MH) microsphere particles were prepared by a facile one-step, self-assembly method. The synthesized products and the mechanism of adsorption of samples of the anthraquinone dyes reactive blue 19 (RB19) and alizarin red S (ARS) were analyzed by different modern characterization techniques, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectrometry (EDS), the Brunauer-Emmett-Teller (BET) method and Fourier transform infrared (FT-IR) spectroscopy. The adsorptive potential of the as-prepared microspheres for the removal of RB19 and ARS in aqueous solution was evaluated. The effects of multiple condition parameters, including, adsorbent dosage, adsorption time, adsorption temperature, wastewater pH, rotating speed and sodium chloride concentration on the removal of the dyes from the wastewater were studied in detail. The effect of the structural and shape properties of the MH adsorbent on the dye adsorption performances was also studied. The results showed that sunflower torus-like MH was an effective adsorbent for dye removal. The removal rates of ARS and RB19 were 91.65% and 83.03%, respectively, under the optimized conditions. The maximum adsorption capacity of the microspheres was 349.85mg/g for ARS and 231.78mg/g for RB19 at 25 oC. The equilibrium adsorption experimental data of the microsphere adsorption conformed to the Freundlich isotherm for ARS and the Langmuir isotherm for RB19. The adsorption kinetics experimental studies showed that the pseudo-second-order and pseudo-first-order model perfectly fit for both ARS and RB19 microsphere adsorption. RB19 and ARS were absorbed on the sunflower torus-like MH surface via the formation of H-bonds. Thus, the sunflower torus-like MH microsphere particles are an effective purifying agent for the removal of the anthraquinone dyes ARS and RB19 from wastewater.

Genome-Wide Association Study Meta-Analysis Reveals Transethnic Replication of Mean Arterial and Pulse Pressure Loci

Kelly, Tanika N.,Takeuchi, Fumihiko,Tabara, Yasuharu,Edwards, Todd L.,Kim, Young Jin,Chen, Peng,Li, Huaixing,Wu, Ying,Yang, Chi-Fan,Zhang, Yonghong,Gu, Dongfeng,Katsuya, Tomohiro,Ohkubo, Takayoshi,Gao American Heart Association, Inc. 2013 Hypertension Vol.62 No.5

<P>We conducted a genome-wide association study meta-analysis of mean arterial pressure and pulse pressure among 26 600 East Asian participants (stage 1) followed by replication study of up to 28 783 participants (stage 2). For novel loci, statistical significance was determined by a <I>P</I><5.0×10<SUP>–8</SUP> in joint analysis of stage 1 and stage 2 data. For loci reported by the previous mean arterial and pulse pressure genome-wide association study meta-analysis in Europeans, evidence of transethnic replication was determined by consistency in effect direction and a Bonferroni-corrected <I>P</I><1.4×10<SUP>–3</SUP>. No novel loci were identified by the current study. Five independent mean arterial pressure variants demonstrated robust evidence for transethnic replication including rs17249754 at <I>ATP2B1</I> (<I>P</I>=7.5×10<SUP>–15</SUP>), rs2681492 at <I>ATP2B1</I> (<I>P</I>=3.4×10<SUP>–7</SUP>), rs11191593 at <I>NT5C2</I> (1.1×10<SUP>–6</SUP>), rs3824755 at <I>CYP17A1</I> (<I>P</I>=1.2×10<SUP>–6</SUP>), and rs13149993 at <I>FGF5</I> (<I>P</I>=2.4×10<SUP>–4</SUP>). Two additional variants showed suggestive evidence of transethnic replication (consistency in effect direction and <I>P</I><0.05), including rs319690 at <I>MAP4</I> (<I>P</I>=0.014) and rs1173771 at <I>NPR3</I> (<I>P</I>=0.018). For pulse pressure, robust evidence of replication was identified for 2 independent variants, including rs17249754 at <I>ATP2B1</I> (<I>P</I>=1.2×10<SUP>–5</SUP>) and rs11191593 at <I>NT5C2</I> (<I>P</I>=1.1×10<SUP>–3</SUP>), with suggestive evidence of replication among an additional 2 variants including rs3824755 at <I>CYP17A1</I> (<I>P</I>=6.1×10<SUP>–3</SUP>) and rs2681492 at <I>ATP2B1</I> (<I>P</I>=9.0×10<SUP>–3</SUP>). Replicated variants demonstrated consistency in effect sizes between East Asian and European samples, with effect size differences ranging from 0.03 to 0.24 mm Hg for mean arterial pressure and from 0.03 to 0.21 mm Hg for pulse pressure. In conclusion, we present the first evidence of transethnic replication of several mean arterial and pulse pressure loci in an East Asian population.</P>