Regulating the electronic structures of mixed B-site pyrochlore to enhance the turnover frequency in water oxidation

Zhang Cheng,Wang Fangfang,Xiong Beichen,Yang Hong 나노기술연구협의회 2022 Nano Convergence Vol.9 No.22

This paper describes the development of mixed B-site pyrochlore Y2MnRuO7 electrocatalyst for oxygen evolution reaction (OER) in acidic media, a challenge for the development of low-temperature electrolyzer for green hydrogen production. Recently, several theories have been developed to understand the reaction mechanism for OER, though there is an uncertainty in most of the cases, due to the complex surface structures. Several key factors such as lattice oxygen, defect, electronic structure, oxidation state, hydroxyl group and conductivity were identified and shown to be important to the OER activity. The contribution of each factor to the performance however is often not well understood, limiting their impact in guiding the design of OER electrocatalysts. In this work, we showed mixed B-site pyrochlore Y2MnRuO7 catalyst exhibits 14 times higher turnover frequency (TOF) than RuO2 while maintaining a low overpotential of ~ 300 mV for the entire testing period of 24 h in acidic electrolyte. X-ray photoelectron spectroscopy (XPS) analysis reveals that this B-site mixed pyrochlore Y2MnRuO7 has a higher oxidation state of Ru than those of Y2Ru2O7, which could be crucial for improving OER performance as the broadened and lowered Ru 4d band resulted from the B-site substitution by Mn is beneficial to the OER kinetics.

Two d¹⁰ Metal Coordination Polymers Based on 1H-1,2,4-Triazole: Synthesis, Structure and Fluorescence

Zhang, Xiu-Cheng,Xu, Ling,Liu, Wen-Guang,Liu, Bing Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

The reactions of 1H-1,2,4-triazole (Htr) with $MX_2$ ($ZnCl_2$ for 1; $CdBr_2$ for 2) resulted in two coordination polymers, [Zn(tr)Cl]$_n$ (1) and $[Cd(Htr)_2Br_2]_n$ (2). The structural analyses indicate that 1 and 2 feature a 2D layer and 1D triple chain, respectively. In 1, neighouring Zn atoms are connected by ${\mu}_3-1$ ${\kappa}N$: 2 ${\kappa}N$: $4{\kappa}N-tr^-$ anionic ligand into 6- and 16-membered rings, further grow into a 2D sheet. Cd atoms in 2 are bonded by two ${\mu}_2-Br^-$ bridges and neutral ${\mu}_2$-1 ${\kappa}N$: 2 ${\kappa}N$-Htr to form a 1D triple chain. The fluorescent characterizations of 1, 2 and the free Htr ligand feature simlilar emission peakes at 444, 446 and 423 nm respectively, which can be assigned to intra-ligand ${\pi}-{\pi}^*$ transition of (H)tr. The energy gaps of 5.90 eV for 1, 5.16 eV for 2, and 5.93 eV for Htr suggest that the compounds behave as insulators.

A synthetic decursin analog with increased in vivo stability suppresses androgen receptor signaling in vitro and in vivo.

Zhang, Yong,Shaik, Ahmad Ali,Xing, Chengguo,Chai, Yubo,Li, Li,Zhang, Jinhui,Zhang, Wei,Kim, Sung-Hoon,L?, Junxuan,Jiang, Cheng M. Nijhoff ; Kluwer Academic Publishers 2012 Investigational new drugs Vol.30 No.5

<P>Targeting androgen receptor (AR) signaling with agents distinct from current antagonist drugs remains a rational approach to the prevention and treatment of prostate cancer (PCa). Our previous studies have shown that decursin and isomer decursinol angelate (DA), isolated from the Korean medicinal herb Angelica gigas Nakai, interrupt AR signaling and possess anti-PCa activities in vitro. In the LNCaP PCa cell model, these pyranoccoumarin compounds exhibit properties distinct from currently used antagonists (e.g., Casodex). However, both are rapidly de-esterified to decursinol, a partial AR agonist. We report here that a synthetic decursin analog, decursinol phenylthiocarbamate (DPTC), has greater in vivo stability than the parent compounds. DPTC-decursinol conversion was undetectable in mice. Furthermore, in LNCaP cells, DPTC decreased prostate specific antigen (PSA) expression, down-regulated AR abundance and mRNA and inhibited AR nuclear translocation. The effect of DPTC on AR and PSA mRNA and protein abundance was also observed in VCaP cells expressing wild type AR. DPTC inhibited growth of both PCa cell lines through G(1) cell cycle arrest and apoptosis, as did decursin and DA. Furthermore, i.p. administration of DPTC for 3 weeks suppressed the expression of AR target genes probasin and Nkx3.1 in mouse prostate glands. Overall, our data suggest that DPTC represents a prototype lead compound for development of in vivo stable and active novel decursin analogs for the prevention or therapy of PCa.</P>

Influence of FeSe doping on superconducting properties of MgB2 by hybrid microwave method

Cheng Cheng,Zhenjie Feng,Qing Li,Xu Wang,Chuan Yu,Hao Chu,Ya Yang,Changqin Liu,Yiming Cao,Zhe Li,Jingzhe Chen,Chao Jing,Shixun Cao,Jincang Zhang 한국물리학회 2017 Current Applied Physics Vol.17 No.11

The effect of FeSe doping on the physical properties of MgB2 is studied. Bulk samples of the FeSe doped MgB2 with weight ratio x ðFeSe : MgB2Þ ¼ 0%; 3%; 7% and 10% were prepared by hybrid microwave method. It is proved that FeSe is not stable together with MgB2. Fe2þ enters into MgB2 lattice, some Mg2þ and Se2『 are combined into the new impurity compound MgSe. The superconducting transition temperature (Tc) slightly decreased with increasing doping content of FeSe from R-T and M-T curves, which results from the substitution of Mg2þ by Fe2þ in the MgB2 lattice. The Jc increase slightly with the FeSe doping content increasing from 3 wt % to 10 wt %, which results from the increasing MgSe impurity pinning centers.

K-doping effect of the superconductivity in K2xFeTe1-xSx (0.07 ≤ x ≤ 0.3)

Cheng Cheng,Zhenjie Feng,Qing Li,Tao Li,Qiang Hou,Fei Chen,Zhongmin Ou,Jun-Yi Ge,Shixun Cao,Jincang Zhang 한국물리학회 2019 Current Applied Physics Vol.19 No.4

Bulk samples of K doping K2xFeTe1-xSx with x=0.07, 0.1, 0.2, 0.3 are successfully prepared by using easy-to-use stable compound K2S as the reactant. The lattice constant calculated from X-ray diffraction patterns indicate that K ions enter the Fe-Te-S layers. K doping is beneficial enhance the superconductivity transition temperature from the R-T curves. The apparent diamagnetic signal is observed in M-T curves when the content of K is smaller than 0.1. However, differential curves (dM/dT) in K-rich samples appear sharp slope mutations, which means that the Meissner effect signal is covered by the increased excess ferromagnetic ions. The number of excess Fe magnetic ions is proportional to K content, which may play an important role in determining the superconductivity.

Distinctive Roles of Wnt Signaling in Chondrogenic Differentiation of BMSCs under Coupling of Pressure and Platelet-Rich Fibrin

Cheng Baixiang,Feng Fan,Shi Fan,Huang Jinmei,Zhang Songbai,Quan Yue,Tu Teng,Liu Yanli,Wang Junjun,Zhao Ying,Zhang Min 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.4

BACKGROUND: Although newly formed constructs of feasible pressure-preadjusted bone marrow mesenchymal stem cells (BMSCs) and platelet-rich fibrin (PRF) showed biomechanical flexibility and superior capacity for cartilage regeneration, it is still not very clear how BMSCs and seed cells feel mechanical stimuli and convert them into biological signals, and the difference in signal transduction underlying mechanical and chemical cues is also unclear. METHODS: To determine whether mechanical stimulation (hydrostatic pressure) and chemical cues (platelet-rich fibrin, PRF) activate canonical or noncanonical Wnt signaling in BMSCs, BMSCs cocultured with PRF were subjected to hydrostatic pressure loading, and the activation of the Wnt signaling molecules and expression of cartilage-associated proteins and genes were determined by western blotting and polymerase chain reaction (PCR). Inhibitors of canonical or noncanonical Wnt signaling, XVX-939 or L690,330, were adopted to investigate the role of Wnt signaling molecules in mechanically promoted chondrogenic differentiation of BMSCs. RESULTS: Hydrostatic pressure of 120 kPa activated both Wnt/b-catenin signaling and Wnt/Ca2? signaling, with the the maximum promotion effect at 60 min. PRF exerted no synergistic effect on Wnt/b-catenin signaling activation. However, the growth factors released by PRF might reverse the promotion effects of pressure on Wnt/Ca2? signaling. Real-time PCR and Western blotting results showed that pressure could activate the expression of Col-II, Sox9, and aggrecan in BMSCs cocultured with PRF. Blocking experiment found a positive role of Wnt/b-catenin signaling, and a negative role of Wnt/ Ca2? signaling in chondrogenic differentiation of the BMSCs. Mutual inhibition exists between canonical and noncanonical Wnt signaling in BMSCs under pressure. CONCLUSION: Wnt signaling participates in the pressure-promoted chondrogenesis of the BMSCs co-cultured with PRF, with canonical and noncanonical pathways playing distinct roles during the process.

Expression and Clinical Significance of REPS2 in Human Esophageal Squamous Cell Carcinoma

Zhang, Hang,Duan, Chao-Jun,Zhang, Heng,Cheng, Yuan-Da,Zhang, Chun-Fang Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5

Objective: REPS2 plays important roles in inhibiting cell proliferation, migration and in inducing apoptosis of cancer cells, now being identified as a useful biomarker for favorable prognosis in prostate and breast cancers. The purpose of this study was to assess REPS2 expression and to explore its role in esophageal squamous cell carcinoma (ESCC). Methods: Protein expression of REPS2 in ESCCs and adjacent non-cancerous tissues from 120 patients was analyzed by immunohistochemistry and correlated with clinicopathological parameters and patient outcome. Additionally, thirty paired ESCC tissues and four ESCC cell lines and one normal human esophageal epithelial cell line were evaluated for REPS2 mRNA and protein expression levels by quantitative RT-PCR and Western blotting. Results: REPS2 mRNA and protein expression levels were down-regulated in ESCC tissues and cell lines. Low protein levels were significantly associated with primary tumour, TNM stage, lymph node metastasis and recurrence (all, P < 0.05). Survival analysis demonstrated that decreased REPS2 expression was significantly associated with shorter overall survival and disease-free survival (both, P < 0.001), especially in early stage ESCC patients. When REPS2 expression and lymph node metastasis status were combined, patients with low REPS2 expression/lymph node (+) had both poorer overall and disease-free survival than others (both, P < 0.001). Cox multivariate regression analysis further revealed REPS2 to be an independent prognostic factor for ESCC patients. Conclusions: Our findings demonstrate that downregulation of REPS2 may contribute to malignant progression of ESCC and represent a novel prognostic marker and a potential therapeutic target for ESCC patients.

Performance evaluation of soil-embedded plastic optical fiber sensors for geotechnical monitoring

Cheng-Cheng Zhang,Hong-Hu Zhu,Bin Shi,Jun-Kuan She,Dan Zhang 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.17 No.2

Based on the distributed fiber optic sensing (DFOS) technique, plastic optical fibers (POFs) are attractive candidates to measure deformations of geotechnical structures because they can withstand large strains before rupture. Understanding the mechanical interaction between an embedded POF and the surrounding soil or rock is a necessary step towards establishing an effective POF-based sensing system for geotechnical monitoring. This paper describes a first attempt to evaluate the feasibility of POF-based soil deformation monitoring considering the POF–soil interfacial properties. A series of pullout tests were performed under various confining pressures (CPs) on a jacketed polymethyl methacrylate (PMMA) POF embedded in soil specimens. The test results were interpreted using a fiber–soil interaction model, and were compared with previous test data of silica optical fibers (SOFs). The results showed that the range of CP in this study did not induce plastic deformation of the POF; therefore, the POF–soil and the SOF–soil interfaces had similar behavior. CP was found to play an important role in controlling the fiber–soil interfacial bond and the fiber measurement range. Moreover, an expression was formulated to determine whether a POF would undergo plastic deformation when measuring soil deformation. The plasticity of POF may influence the reliability of measurements, especially for monitored geo-structures whose deformation would alternately increase and decrease. Taken together, these results indicate that in terms of the interfacial parameters studied here the POF is feasible for monitoring soil deformation as long as the plastic deformation issue is carefully addressed.

A NEW SOLUTION METHOD FOR STATE EQUATIONS OF NONLINEAR SYSTEM

Zhang, Cheng-Hui,Tan, Cheng-Hui,Cui, Na-Xin 한국전산응용수학회 1999 Journal of applied mathematics & informatics Vol.6 No.1

Along with the computation and analysis for nonlinear system being more and more involved in the fields such as automation control electronic technique and electrical power system the nonlin-ear theory has become quite a attractive field for academic research. In this paper we derives the solutions for state equation of nonlinear system by using the inverse operator expression of the so-lutions is obtained. An actual computation example is given giving a comparison between IOM and Runge-kutta method. It has been proved by our investigation that IOM has some distinct advantages over usual approximation methods in that it is computationally con-venient rapidly convergent provides accurate solutions not requiring perturbation linearization or the massive computation inherent in discrietization methods such as finite differences. So the IOM pro-vides an effective method for the solution of nonlinear system is of potential application valuable in nonlinear computation.

Peroxisome proliferator-activated receptor γ is essential for secretion of ANP induced by prostaglandin D₂ in the beating rat atrium

Zhang, Ying,Li, Xiang,Liu, Li-Ping,Hong, Lan,Liu, Xia,Zhang, Bo,Wu, Cheng-Zhe,Cui, Xun The Korean Society of Pharmacology 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.3

Prostaglandin $D_2$ ($PGD_2$) may act against myocardial ischemia-reperfusion (I/R) injury and play an anti-inflammatory role in the heart. Although the effect of $PGD_2$ in regulation of ANP secretion of the atrium was reported, the mechanisms involved are not clearly identified. The aim of the present study was to investigate whether $PGD_2$ can regulate ANP secretion in the isolated perfused beating rat atrium, and its underlying mechanisms. $PGD_2$ (0.1 to $10{\mu}M$) significantly increased atrial ANP secretion concomitantly with positive inotropy in a dose-dependent manner. Effects of $PGD_2$ on atrial ANP secretion and mechanical dynamics were abolished by AH-6809 ($1.0{\mu}M$) and AL-8810 ($1.0{\mu}M$), $PGD_2$ and prostaglandin $F2{\alpha}$ ($PGF2{\alpha}$) receptor antagonists, respectively. Moreover, $PGD_2$ clearly upregulated atrial peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$) and the $PGD_2$ metabolite 15-deoxy-${\Delta}12$, 14-$PGJ_2$ (15d-$PGJ_2$, $0.1{\mu}M$) dramatically increased atrial ANP secretion. Increased ANP secretions induced by $PGD_2$ and 15d-$PGJ_2$ were completely blocked by the $PPAR{\gamma}$ antagonist GW9662 ($0.1{\mu}M$). PD98059 ($10.0{\mu}M$) and LY294002 ($1.0{\mu}M$), antagonists of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling, respectively, significantly attenuated the increase of atrial ANP secretion by $PGD_2$. These results indicated that $PGD_2$ stimulated atrial ANP secretion and promoted positive inotropy by activating $PPAR{\gamma}$ in beating rat atria. MAPK/ERK and PI3K/Akt signaling pathways were each partially involved in regulating $PGD_2$-induced atrial ANP secretion.