Effect of oxidizing treatment on electrocatalytic activity of boron‑doped amorphous carbon thin films

Chen‑Song Wang,Ni Suo,Hao Huang,Ai‑min Wu,Guo‑Zhong Cao,Gui‑Feng Zhang 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Boron-doped amorphous carbon (BDAC) thin films with a regular oxygen reduction reaction (ORR) catalytic activity were synthesized in a hot filament chemical vapor deposition device using a mixture of CH4 and H2 as a gas source and B2O3 as a boron source and then oxidized in air at 380–470 °C for 15–75 min. Scanning electron microscope, transmission electron microscope, Raman spectroscopy, X-ray photoelectron spectroscopy, and electrochemical tests were used to characterize the physical and electrochemical properties of the BDAC catalysts. It was concluded that the BDAC catalyst oxidized at 450 °C for 45 min showed the best ORR catalytic activity in alkaline medium. The oxygen reduction potential and the transfer electron number n, respectively, are − 0.286 V versus Ag/AgCl and 3.24 from the rotating disk electrode experiments. The treated carbon film has better methanol resistance and stability than the commercial Pt/C catalyst.

Optical Properties of Zinc-oxide Films Determined Using Spectroscopic Ellipsometry with Various Dispersion Models

Zhong-Hong Dai,Jie Shao,Yi-Ming Chen,Yu-Xiang Zheng,Jia-Da Wu,Liang-Yao Chen,Rong-Jun Zhang 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3

In this work, we have studied the optical properties of wurtizite zinc-oxide films grown on silicon (100) substrates by means of pulsed laser deposition (PLD). Spectroscopic ellipsometry and three dispersion models, namely, the Sellmeier, Cauchy, and Forouhi-Bloomer models, were applied for determining the optical constants of the ZnO thin films. A comparison was made between two samples that were deposited for 30 minutes (sample I) and 60 minutes (sample II), respectively. X-ray diffraction analysis indicates that there are two types of preferred-orientation, i.e., (101) and (100) orientations for sample I and II, respectively. Results show that the Cauchy model gives the best fit for the samples with least root mean square error (RMSE) whereas the Forouhi-Bloomer model is most suitable for the data analysis in both the transparent and the absorption regions. The optical properties extracted from different dispersion models have been compared with the data reported in the literature. The results given in this work show that different dispersion models should be applied to obtain the optical constants In this work, we have studied the optical properties of wurtizite zinc-oxide films grown on silicon (100) substrates by means of pulsed laser deposition (PLD). Spectroscopic ellipsometry and three dispersion models, namely, the Sellmeier, Cauchy, and Forouhi-Bloomer models, were applied for determining the optical constants of the ZnO thin films. A comparison was made between two samples that were deposited for 30 minutes (sample I) and 60 minutes (sample II), respectively. X-ray diffraction analysis indicates that there are two types of preferred-orientation, i.e., (101) and (100) orientations for sample I and II, respectively. Results show that the Cauchy model gives the best fit for the samples with least root mean square error (RMSE) whereas the Forouhi-Bloomer model is most suitable for the data analysis in both the transparent and the absorption regions. The optical properties extracted from different dispersion models have been compared with the data reported in the literature. The results given in this work show that different dispersion models should be applied to obtain the optical constants

A comprehensive gene network for fine tuning floral development in poplar

Zhong Chen,Xiaoyu Yang,Xiaoxing Su,Kai Gao,Pian Rao,Xinmin An 한국유전학회 2017 Genes & Genomics Vol.39 No.7

Herbaceous model species, especially Arabidopsis has provided a wealth of information about the genes involved in floral induction and development of inflorescences and flowers. While the genus Populus is an important model system for the molecular biology of woody plant. These two genuses differ in many ways. This study was designed to improve understanding of flower development in poplar at a system level, as its regulatory pathway to a large extent remains poorly known, owing to the presently limited mutant pool. To address this issue, a poplar GeneChip was employed to detect genes expressed during the whole floral developmental process. Using the expressed floral genes, a systematic gene network was constructed with the aid of functional association with Arabidopsis. The results suggested that autonomous, gibberellin, vernalization, photoperiod, ethylene, brassinosteroid, stress-induced and floral suppression pathways are involved in poplar flowering. Modularity analysis revealed several pathways in common with Arabidopsis, such as autonomous, gibberellin, vernalization and photoperiod pathways. In addition, brassinosteroid, stress-induced and floral suppression pathways were implicated as additional novel pathways. Notably, a difference in vernalization between Arabidopsis and poplar was revealed. Autonomous, gibberellin, vernalization, photoperiod, ethylene, brassinosteroid, stress-induced and floral suppression pathways integrated into a systematic gene network in floral development of poplar. Compared to Arabidopsis, brassinosteroid, stressinduced and floral suppression pathways are additional in poplar, and FLC is absent in vernalization pathway in poplar. Preliminary conclusions drawn here provide a basis for both identification of key genes and elucidation of molecular mechanisms involved in poplar floral development.

Protein target identification of ginsenosides in skeletal muscle tissues: discovery of natural small-molecule activators of muscle-type creatine kinase

Chen, Feiyan,Zhu, Kexuan,Chen, Lin,Ouyang, Liufeng,Chen, Cuihua,Gu, Ling,Jiang, Yucui,Wang, Zhongli,Lin, Zixuan,Zhang, Qiang,Shao, Xiao,Dai, Jianguo,Zhao, Yunan The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.3

Background: Ginseng effectively reduces fatigue in both animal models and clinical trials. However, the mechanism of action is not completely understood, and its molecular targets remain largely unknown. Methods: By screening for proteins that interact with the primary components of ginseng (ginsenosides) in an affinity chromatography assay, we have identified muscle-type creatine kinase (CK-MM) as a potential target in skeletal muscle tissues. Results: Biolayer interferometry analysis showed that ginsenoside metabolites, instead of parent ginsenosides, had direct interaction with recombinant human CK-MM. Subsequently, 20(S)-protopanaxadiol (PPD), which is a ginsenoside metabolite and displayed the strongest interaction with CK-MM in the study, was selected as a representative to confirm direct binding and its biological importance. Biolayer interferometry kinetics analysis and isothermal titration calorimetry assay demonstrated that PPD specifically bound to human CK-MM. Moreover, the mutation of key amino acids predicted by molecular docking decreased the affinity between PPD and CK-MM. The direct binding activated CK-MM activity in vitro and in vivo, which increased the levels of tissue phosphocreatine and strengthened the function of the creatine kinase/phosphocreatine system in skeletal muscle, thus buffering cellular ATP, delaying exercise-induced lactate accumulation, and improving exercise performance in mice. Conclusion: Our results suggest a cellular target and an initiating molecular event by which ginseng reduces fatigue. All these findings indicate PPD as a small molecular activator of CK-MM, which can help in further developing better CK-MM activators based on the dammarane-type triterpenoid structure.

Hydrogen Bonding Analysis of Hydroxyl Groups in Glucose Aqueous Solutions by a Molecular Dynamics Simulation Study

Chen, Cong,Li, Wei Zhong,Song, Yong Chen,Weng, Lin Dong,Zhang, Ning Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.7

Molecular dynamics simulations have been performed to investigate hydrogen bonding characteristics of hydroxyl groups in glucose aqueous solutions with different concentrations. The hydrogen bonding abilities and strength of different O and H atom types have been calculated and compared. The acceptor/donor efficiencies have been predicted and it has been found that: (1) O2-HO2 and O3-HO3 are more efficient intramolecular hydrogen bonding acceptors than donors; (2) O1-HO1, O4-HO4 and O6-HO6 are more efficient intramolecular hydrogen bonding donors than acceptors; (5) O1-HO1 and O6-HO6 are more efficient intermolecular hydrogen bonding acceptors than donors while hydroxyl groups O2-HO2 and O4-HO4 are more efficient intermolecular hydrogen bonding donors than acceptors. The hydrogen bonding abilities of hydroxyl groups revealed that: (1) the hydrogen bonding ability of OH2-$H_w$ is larger than that of hydroxyl groups in glucose; (2) among the hydroxyl groups in glucose, the hydrogen bonding ability of O6-HO6 is the largest and the hydrogen bonding ability of O4-HO4 is the smallest; (3) the intermolecular hydrogen bonding ability of O6-HO6 is the largest; (4) the order for intramolecular hydrogen bonding abilities (from large to small) is O2-HO2, O1-HO1, O3-HO3, O6-HO6 and O4-HO4.

Amphiregulin secreted by cartilage endplate stem cells inhibits intervertebral disk degeneration and TNF-α production via PI3K/AKT and ERK1/2 signaling pathways

Chen Qin,Wu Yaohong,Zhong Mingliang,Xu Chanhua,Chen Rongchun,Liu Ning 대한독성 유전단백체 학회 2023 Molecular & cellular toxicology Vol.19 No.2

Background Intervertebral disk degeneration (IDD) is a common orthopedic disorder, and nucleus pulposus cells (NPCs) serve to stabilize the intervertebral disk. Objective This study was implemented to explore the protective eff ect of endplate stem cells (EPSCs) on IDD. NPCs and EPSCs were isolated from rats and tert -Butyl peroxide (TBHP) was used to treat NPCs and simulate IDD. EPSC-derived conditioned medium (CM) was collected and mixed with a culture medium at diff erent proportions, which was then used to treat NPCs. SOD assay was employed to examine the oxidative stress level in the NPCs. To assess apoptosis and caspase-3 activity, fl ow cytometry and western blots for cleaved PARP1 and BAX were carried out. The mRNA expression levels of diff erent genes were detected by quantitative real-time polymerase chain reaction. Furthermore, the concentrations of amphiregulin (Areg) and infl ammatory factors were measured with ELISA kits and cell signaling pathways were evaluated using western blotting. Results Following TBHP treatment, caspase-3 activity in the NPCs increased. However, exposing TBHP-induced NPCs to the EPSC-derived CM reduced oxidative stress, caspase-3 activity, cell apoptosis, fi brotic response, and cytokine production. Additionally, the EPSC-derived CM contained a higher concentration of Areg compared to that in the NPCs. Furthermore, Areg decreased oxidative stress, cell apoptosis, fi brosis, and infl ammation via both PI3K/AKT and ERK1/2 signaling pathways. Conclusion ECSCs reduce NPC apoptosis, oxidative stress, production of infl ammatory factors, and fi brotic response via the release of Areg. Moreover, Areg can exert these protective eff ects on NPCs via PI3K/AKT and ERK1/2 signaling pathways.

Discovery of Anticostia uniformis from the Xiazhen Formation at Zhuzhai, South China and its stratigraphic implication

Chen, Zhong-Yang,Kim, Myong-Hak,Choh, Suk-Joo,Lee, Dong-Jin,Chen, Xu Elsevier 2016 Palaeoworld Vol.25 No.3

<P>The Xiazhen Formation is an Upper Ordovician lithostratigraphic unit in the Jiangshan-Changshan-Yushan (JCY) area, which contains series of Late Ordovician reef successions. The reef successions of the Xiazhen Formation at Zhuzhai are critical for evaluation of the Late Ordovician marine diversity and palaeoecology. However, their age has long been uncertain and generally is regarded as of upper Katian, based on the occurrences of shelly fossils and correlation with the stratigraphic equivalent Changwu Formation. The newly discovered graptolite species Anticostia uniformis, in the Xiazhen Formation, together with the combined evidence of brachiopods and sedimentology, indicates an age range for the graptolite locality from the Dicellograptus complanatus Biozone to the Diceratograptus mirus Subzone of late Katian, but the graptolites do not rule out the possibility that it is Hirnantian. (C) 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.</P>

Transport of Runaway Electrons in Sawtooth Active Plasmas in the HT-7 Tokamak

Zhong Yong Chen,Wei Jin,Yang Zhang 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.7

The magnetic fluctuation level is an important parameter in lower hybrid current-drive (LHCD) plasmas because LHCD has been used to improve plasma performance extensively in the HT-7 tokamak. We investigate the transport of runaway electrons in LHCD plasmas with strong sawteeth in the HT-7 tokamak. A delay time was found to exist between the peak of the soft X-ray sawteeth and the peak of the hard X-ray flux. Based on the delay time, we obtained the transport coefficient of the runaway electrons and the averaged magnetic fluctuation level in sawtooth activity of the plasmas. We found that the diffusion coefficient of the runaway electrons was on the order of <i>D_r</i> ∼ 1 m²s⁻¹ and that the magnetic fluctuation level was on the order of <i>˜b</i> ∼ 10⁻⁶.

Observation of the Trapping of Runaway Electrons into Local Magnetic Mirrors during Slide-away Discharges in the HT-7 Tokamak

Zhong Yong Chen,Bao Nian Wan,Yuejiang Shi 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.2

The trapping of runaway electrons into local magnetic mirrors in a toroidal magnetic field has been observed in slide away discharges in the HT-7 tokamak. When the discharges went into the slide-away region with Parail-Pogutse instabilities, strong oscillations in the hard X-ray flux and in the electron cyclotron emission are observed. The runaway electrons are trapped into the local magnetic mirrors when they are pitch angle scattered by the anomalous Doppler resonance effect.

Nitrogen and Fluorine Dual-Doped Carbon Nanosheets for High-Performance Supercapacitors

Chen Jiao,Zhong Jie Zhang,Xiang Ying Chen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4

Doping carbon materials with heteroatoms such as N, F is an effective approach to elevating the capacitive performance of supercapacitors. In this paper, nitrogen and fluorine dual-doped two-dimensional (2D) porous carbon nanosheets (PCNSs) have been fabricated by a straightforward template carbonization method, using trisodium citrate as carbon source and self-template, and ammonium fluoride as N/F dopants. The N/F-doped carbon samples are well characterized by a series of techniques and measured in a three-electrode system and two-electrode system, respectively. As a result, N/F-doped carbon has delivered large capacitance of 110 F g -1 at 1 Ag -1 and high-energy density of 3.82 W h kg -1 at the power density of 0.5 kW kg -1. It is also revealed that semi-ionic C–F bonds in PCNSs have enhanced electrical conductivity, hence, facilitating electron transport in the electrode. For comparison, ammonium chloride is used as sole dopant for producing N-doped carbon materials, whose capacitive performances are much lower than the N/F-codoped one, indicating the synergistic effect of N/F for capacitive improvement.