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Hong-Yan Zhao,Wei Liu,Yi Wang,Nannan Dai,Jian-Hong Gu,Yan Yuan,Xue-Zhong Liu,Jian-Chun Bian,Zong-Ping Liu 대한수의학회 2015 Journal of Veterinary Science Vol.16 No.3
Exposure to cadmium (Cd) induces apoptosis in osteoblasts (OBs); however, little information is available regarding the specific mechanismsof Cd-induced primary rat OB apoptosis. In this study, Cd reduced cell viability, damaged cell membranes and induced apoptosis in OBs. We observed decreased mitochondrial transmembrane potentials, ultrastructure collapse, enhanced caspase-3 activity, and increasedconcentrations of cleaved PARP, cleaved caspase-9 and cleaved caspase-3 following Cd treatment. Cd also increased the phosphorylationof p38-mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases (ERK)1/2 and c-jun N-terminal kinase (JNK) in OBs. Pretreatment with the caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, ERK1/2 inhibitor (U0126), p38 inhibitor(SB203580) and JNK inhibitor (SP600125) abrogated Cd-induced cell apoptosis. Furthermore, Cd-treated OBs exhibited signs of oxidativestress protection, including increased antioxidant enzymes superoxide dismutase and glutathione reductase levels and decreased formationof reactive oxygen species. Taken together, the results of our study clarified that Cd has direct cytotoxic effects on OBs, which are mediatedby caspase- and MAPK pathways in Cd-induced apoptosis of OBs.
Liu, Jinhuan,Ju, Mujie,Wu, Yifei,Leng, Nannan,Algharib, Samah Attia,Luo, Wanhe The Korean Society of Veterinary Science 2022 Journal of Veterinary Science Vol.23 No.5
Background: Florfenicol might be ineffective for treating Staphylococcus aureus small colony variants (SCVs) mastitis. Objectives: In this study, florfenicol-loaded chitosan (CS)-sodium tripolyphosphate (TPP) composite nanogels were prepared to allow targeted delivery to SCV infected sites. Methods: The formulation screening, the characteristics, in vitro release, antibacterial activity, therapeutic efficacy, and biosafety of the florfenicol composite nanogels were studied. Results: The optimized formulation was obtained when the CS and TPP were 10 and 5 mg/mL, respectively. The encapsulation efficiency, loading capacity, size, polydispersity index, and zeta potential of the optimized florfenicol composite nanogels were 87.3% ± 2.7%, 5.8% ± 1.4%, 280.3 ± 1.5 nm, 0.15 ± 0.03, and 36.3 ± 1.4 mv, respectively. Optical and scanning electron microscopy showed that spherical particles with a relatively uniform distribution and drugs might be incorporated in cross-linked polymeric networks. The in vitro release study showed that the florfenicol composite nanogels exhibited a biphasic pattern with the sustained release of 72.2% ± 1.8% at 48 h in pH 5.5 phosphate-buffered saline. The minimal inhibitory concentrations of commercial florfenicol solution and florfenicol composite nanogels against SCVs were 1 and 0.25 ㎍/mL, respectively. The time-killing curves and live-dead bacterial staining showed that the florfenicol composite nanogels were concentration-dependent. Furthermore, the florfenicol composite nanogels displayed good therapeutic efficacy against SCVs mastitis. Biological safety studies showed that the florfenicol composite nanogels might be a biocompatible preparation because of their non-toxic effects on the renal tissue and liver. Conclusions: Florfenicol composite nanogels might improve the treatment of SCV infections.
Nannan Dang,Wei Wang,Jiazhong Zhang,Yan Liu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
The bifurcation analysis of nonlinear combustion instability in a Rijke burner is studied numerically. First, a saturated flame model and a third-order saturated flame model are proposed, and the mode truncation effects are investigated by studying their influences on system eigenvalues. Then, bifurcation analysis on the flame location, average flame intensity, damping, and time delay in the flame model is conducted with the new flame models. Results show that the burner driven by the saturated model loses stability via supercritical Hopf bifurcations, whereas the system driven by the third-order saturated model shows the characteristic of subcritical Hopf bifurcations, accompanied by bistable regimes emerging in the bifurcation diagrams. Finally, the effects of velocity perturbations are analyzed further, and the results show that a given system may oscillates with different frequencies if the disturbance is imposed to different Galerkin modes. This study reveals that the process of the combustion system’s transition to instability depends strongly on the nonlinear term in the flame model.
Study of the Effective Field Emitting Angle for an Individual Carbon Nanotube
Nannan Li,Zhe Wu,Jianlong Liu,Hai Zhang,Jing Guo,Baoqing Zeng 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.6
In this work, the effective field emitting angle θeff is introduced for a carbon nanotube (CNT)to relate the spatial variation of the current density along the tip’s surface to the emission current. The emission current can now be calculated by using I = 2π(1-cosθeff )r2J(0), where J(0) is theemission current density at the apex and r is the radius of curvature of the tips. Analytical resultsshow that θeff depends on the macroscopic field E0, the aspect ratio h/r and the normalized fielddistribution on the tip’s surface E(θ)/E(0). Simulation results show that E(θ)/E(0) converges withincreasing h/r and can be fitted by using a formula when h/r > 500. Finally, a fit function for θeff is obtained for h/r > 500 and E0 in the range of 1 - 25 V/µm.
Nannan Zhang,Diqiu Liu,Wei Zheng,Hua He,Bo Ji,Qing Han,Feng Ge,Chaoyin Chen 한국유전학회 2014 Genes & Genomics Vol.36 No.6
The basic leucine zipper (bZIP) proteins areubiquitous in plants and play important roles in plantdefense responses. In this study, based on an expressedsequence tag from a suppression subtractive hybridizationcDNA library of Lilium regale Wilson during Fusariumoxysporum f. sp. lilii infection, a novel bZIP transcriptionfactor gene LrbZIP1 was isolated from L. regale root usingthe rapid amplification of cDNA ends method. The predictedprotein of LrbZIP1 with 142 amino acid residuescontains a basic domain signature and a leucine zippermotif. The quantitative reverse transcription-PCR (qRTPCR)analysis showed that the transcription level of Lrb-ZIP1 was higher in roots of L. regale than in young stemsand leaves. Moreover, the expression of LrbZIP1 was upregulatedin the incompatible interaction between L. regaleand F. oxysporum f. sp. lilii as well as after treatments withstress-related signaling molecules. To verify the function ofLrbZIP1, a constitutive expression vector of LrbZIP1 wasconstructed and transferred into tobacco (Nicotiana tabacumL. cv Xanthi). The results of Southern blotting andqRT-PCR analyses demonstrated that the LrbZIP1 wasintegrated into genome of the tobacco transformants andhighly expressed. Under normal conditions, the T1 transgenictobacco lines showed higher antioxidant enzymeactivities and transcription levels of several resistancerelatedgenes than the wild type. Moreover, the T1 transgenictobacco plants showed strong resistance to F. oxysporumf. sp. lilii infection.
Jinhuan Liu,Mujie Ju,Yifei Wu,Nannan Leng,Samah Attia Algharib,Wanhe Luo 대한수의학회 2022 Journal of Veterinary Science Vol.23 No.5
Background: Florfenicol might be ineffective for treating Staphylococcus aureus small colony variants (SCVs) mastitis. Objectives: In this study, florfenicol-loaded chitosan (CS)-sodium tripolyphosphate (TPP) composite nanogels were prepared to allow targeted delivery to SCV infected sites. Methods: The formulation screening, the characteristics, in vitro release, antibacterial activity, therapeutic efficacy, and biosafety of the florfenicol composite nanogels were studied. Results: The optimized formulation was obtained when the CS and TPP were 10 and 5 mg/mL, respectively. The encapsulation efficiency, loading capacity, size, polydispersity index, and zeta potential of the optimized florfenicol composite nanogels were 87.3% ± 2.7%, 5.8% ± 1.4%, 280.3 ± 1.5 nm, 0.15 ± 0.03, and 36.3 ± 1.4 mv, respectively. Optical and scanning electron microscopy showed that spherical particles with a relatively uniform distribution and drugs might be incorporated in cross-linked polymeric networks. The in vitro release study showed that the florfenicol composite nanogels exhibited a biphasic pattern with the sustained release of 72.2% ± 1.8% at 48 h in pH 5.5 phosphate-buffered saline. The minimal inhibitory concentrations of commercial florfenicol solution and florfenicol composite nanogels against SCVs were 1 and 0.25 μg/mL, respectively. The time-killing curves and live–dead bacterial staining showed that the florfenicol composite nanogels were concentration-dependent. Furthermore, the florfenicol composite nanogels displayed good therapeutic efficacy against SCVs mastitis. Biological safety studies showed that the florfenicol composite nanogels might be a biocompatible preparation because of their non-toxic effects on the renal tissue and liver. Conclusions: Florfenicol composite nanogels might improve the treatment of SCV infections.
중국어 ‘上’의 허사 쓰임에 나타난 한국인 학습자의 습득 양상 연구
유해도(Liu, Haitao),왕난난(Nannan Wang) 언어과학회 2021 언어과학연구 Vol.- No.96
This paper has investigated Korean Learners’ acquisition of each semantic type of ‘Shang’ in the constructions of ‘noun + Shang’ and ‘verb/adjective + Shang’ by learner corpus. The research results suggest that: (1) There is no significant difference in Korean Learners’ total acquisition achievements of ‘Shang’ after nouns and ‘Shang’ after verbs or adjectives. (2) In the constructions of ‘noun + Shang’ and ‘verb/Adjective + Shang’, Korean learners’ acquisition achievements of each semantic type of ‘Shang’ are different, which are mainly affected by their Chinese proficiency, but the scope of influence is different. (3) The reasons for the differences in Korean Learners’ acquisition achievements of the function word ‘Shang’ are mostly shaped by target item complexity, mother tongue influence and input frequency.
Huan Liu,Nannan Lu,Xiaojun Wang,Xiaoshi Hu,Deqiang Chen 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3
In this study, the wear behaviors of the solution-treated and as-extruded SiCp/AZ91D metal matrix composites with differentsizes and volume fractions of SiC particles were systematically investigated under different wear test parameters. The SiCparticles exhibited a typical necklace-type distribution in the solution-treated composites and a homogeneous distributionin the as-extruded composites. Wear tests results showed that the wear rates of the as-extruded composites were lower thanthat of the solution-treated composites almost under all testing conditions and with the same SiC size and volume fraction. However, the dominant wear mechanisms for these two types of composites were different. The typical necklace-type distributionof SiCpin the solution-treated composites could effectively promote the occurrence of delamination owing to theweak bonding between SiCpand matrix in the particle aggregated regions. By contrast, as the bond between disperse SiCpand matrix was enhanced, the homogeneous distribution of SiCpin the as-extruded composites could promote the occurrenceof adhesion and prevent the occurrence of delamination. Moreover, a higher applied load and higher volume fraction of SiCpobviously promoted the progress of delamination for the solution-treated composites, while the extent of the adhesive wear forthe as-extruded composites was mainly associated with the increase of the applied load, sliding velocity and SiC particle size.