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Lifang Zhang,Ning Li,Yan Wang,Jizhe Guo,Junfei Li 한국고분자학회 2014 Macromolecular Research Vol.22 No.6
Block aliphatic polyesters can be useful for medical and pharmaceutical applications. These materials canbe prepared by sequential ring-opening polymerization reactions. In this work, a set of poly(ε-caprolactone)-poly(Llactide)aliphatic polyester AB diblock copolymers and poly(L-lactide)-poly(ε-caprolactone)-poly(L-lactide) aliphaticpolyester ABA triblock copolymers were prepared by consecutive controlled ring-opening polymerizations. Ring-openingpolymerization of ε-caprolactone in the presence of 1-isopropyl-3-(4-methoxyphenyl) imidazol-2-ylidene and ethyleneglycol offered α,ω-dihydroxyl-terminate poly(ε-caprolactone). An array of poly(L-lactide)-poly(ε-caprolactone)-poly(L-lactide) triblock copolymers with controlled molecular weights and narrow molecular weight distributions wassynthesized using the telechelic poly(ε-caprolactone) samples as macroinitiators for the ring-opening polymerizationof L-lactide. 1H NMR and 13C NMR spectral data of copolymers showed the chemical structures without random placement. Meanwhile, the spectral data also indicated that this polymerization mechanism was in agreement with the activatedmonomer mechanism.
Fabrication and properties of reaction-bonded SiC prepared by gelcasting
Lifang Nie,Hongyu Gong,Tao Zhang,Yujun Zhang 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
The properties of green and reaction-bonded SiC (RBSC) samples prepared by a gelcasting technique are investigated in this paper. The results show that solid loading and monomer content of the suspension in the gelcasting process are the main factors that effect the density and shrinkage of the green bodies. A slurry with a solid loading of 58 vol% was solidified in situ to a green body with a linear shrinkage of 1.1% and flexural strength of 27 ± 2 MPa. SEM micrographs show that the SiC and C particles in the green body were closely compact by a connection of the polymer network. The maximum density and flexural strength of samples reaction sintered at 1700℃ in vacuum were 2.97 g/㎤ and 378 ± 12 MPa respectively. The properties of green and reaction-bonded SiC (RBSC) samples prepared by a gelcasting technique are investigated in this paper. The results show that solid loading and monomer content of the suspension in the gelcasting process are the main factors that effect the density and shrinkage of the green bodies. A slurry with a solid loading of 58 vol% was solidified in situ to a green body with a linear shrinkage of 1.1% and flexural strength of 27 ± 2 MPa. SEM micrographs show that the SiC and C particles in the green body were closely compact by a connection of the polymer network. The maximum density and flexural strength of samples reaction sintered at 1700℃ in vacuum were 2.97 g/㎤ and 378 ± 12 MPa respectively.
Zhang, Daopeng,Zhang, Lifang,Zhao, Zengdian,Ni, Zhonghai Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.8
Two pyridinecarboxamide cobalt dicyanide building blocks and Mn(III) compounds have been employed to assemble cyanide-bridged heterometallic complexes, resulting in three trinuclear cyanide-bridged $Co^{III}-Mn^{II}$ complexes: $\{[Mn(MeOH)_4][Co(bpb)(CN)_2]_2\}{\cdot}2MeOH{\cdot}2H_2O$ (1), $\{[Mn(MeOH)_4][Co(bpmb)(CN)_2]_2\}{\cdot}2MeOH{\cdot}2H_2O$ (2) and $\{[Mn(DMF)_2(en)_2][Co(bpb)(CN)_2]_2\}{\cdot}2DMF{\cdot}H_2O$ (3) ($bpb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)benzenate, $bpmb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, en = ethylenediamine). Single crystal X-ray diffraction analysis shows their similar sandwich-like structures, in which the two cyanide-containing building blocks act as monodentate ligands through one of their two cyanide groups to coordinate the Mn(II) center. For complex 3, it was further linked into one-dimensional structure by ethylenediamine acting as bridges. Investigation of the magnetic properties of complex 3 reveals weak antiferromagnetic coupling between the neighboring Mn(II) centers through the bridging ethylenediamine molecule. A best-fit to the magnetic susceptibilities of complex 3 gave the magnetic coupling constant J = -0.073(2) $cm^{-1}$.
Research on the Construction of the High-efficiency Modern Agricultural Demonstration Park
Lilei Zhang,Shaowei Zhang,Lifang Qiao 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.3
The high-efficiency modern agricultural demonstration park is a new development mode of Chinese agriculture, and plays a very important role in promoting agricultural development. This paper establishes the framework of the modern high-efficiency agricultural demonstration park from six aspects, namely, development orientation, function composition, comprehensive planning, smart construction, standardized construction and innovation construction. The results show that these aspects are influenced by several factors or set up by several modules, and form the symbiotic network of the park. Positioning realistic development targets, arranging function division, allocating infrastructure, and integrating smart, standardized & innovative technologies will ultimately enhance the ecological, economic and social benefits of the park.
Daopeng Zhang,Lifang Zhang,Zengdian Zhao,Zhonghai Ni 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8
Two pyridinecarboxamide cobalt dicyanide building blocks and Mn(III) compounds have been employed to assemble cyanide-bridged heterometallic complexes, resulting in three trinuclear cyanide-bridged CoIII-MnII complexes: {[Mn(MeOH)_4][Co(bpb)(CN)_2]_2}·2MeOH·2H_2O (1), {[Mn(MeOH)_4][Co(bpmb)(CN)_2]_2}·2MeOH·2H_2O (2) and {[Mn(DMF)_2(en)_2][Co(bpb)(CN)_2]_2}·2DMF·H_2O (3) (bpb^2− = 1,2-bis(pyridine-2-carboxamido)benzenate,bpmb^2− = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, en = ethylenediamine). Single crystal X-ray diffraction analysis shows their similar sandwich-like structures, in which the two cyanide-containing building blocks act as monodentate ligands through one of their two cyanide groups to coordinate the Mn(II) center. For complex 3, it was further linked into one-dimensional structure by ethylenediamine acting as bridges. Investigation of the magnetic properties of complex 3 reveals weak antiferromagnetic coupling between the neighboring Mn(II) centers through the bridging ethylenediamine molecule. A best-fit to the magnetic susceptibilities of complex 3 gave the magnetic coupling constant J = −0.073(2) cm^−1.
Lifang Jin,Jian Ni,Shaohui Ji,Mei Shen,Jianlong Zhang,Jiwei Han 한국통합생물학회 2014 Animal cells and systems Vol.18 No.4
Mesenchymal stem cells (MSCs) derived from rabbit bone marrow are routinely investigated in cardiovascularand orthopedic models for regenerative medicine application. However, classical medium used for generatingrabbit MSCs (rbMSCs) was supplemented with fetal bovine serum (FBS), which would raise several safetyconcerns and inconsistencies in the generation of MSCs. Here, we tested a serum-free medium for culture ofrbMSCs through the investigation of multiple parameters including cell morphology, expansion, phenotype,and trilineage differentiation. RbMSCs were isolated using the gradient centrifugation method, and expandedin StemPro® MSC SFM in the presence of substrates and basic fibroblast growth factor (bFGF). Cells werethen characterized by phase contrast microscopy observation, cell proliferation analysis, immunocytochemistrystaining, RT-PCR, and qPCR analysis. Similar to that achieved with FBS-containing culture medium, theviability and proliferation of rbMSCs were improved in serum-free medium supplemented with bFGF and precoatedwith CELLstartTM. Serum-free expanded rbMSCs showed the fibroblastic spindle-shape morphology,and were positive for CD29, CD44, and CD73, and negative for CD34, CD45, and CD166. After thecorresponding differentiation, rbMSCs from serum-free condition were demonstrated to differentiate intoadipogenic, osteogenic, and chondrogenic lineages. In addition, differences were also observed betweenrbMSCs cultured with or without serum in terms of their morphology, proliferation, and gene expression levelsof early differentiation transcription factors. In conclusion, this study demonstrates that rbMSCs can beexpanded in a serum-free condition while maintaining the original characteristics of MSCs, which provides auseful tool to understand the basic biological properties of rbMSCs in culture.
Inactivation of Vibrio parahaemolyticus by Aqueous Ozone
( Lifang Feng ),( Kuo Zhang ),( Mengsha Gao ),( Chunwei Shi ),( Caiyun Ge ),( Daofeng Qu ),( Junli Zhu ),( Yugang Shi ),( Jianzhong Han ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.8
Vibrio parahaemolyticus contamination causes serious foodborne illness and has become a global health problem. As a disinfectant, aqueous ozone can effectively kill a number of bacteria, viruses, parasites, and other microorganisms. In this study, three factors, namely, the aqueous ozone concentration, the exposure time, and the bacterial density, were analyzed by response surface methodology, and the aqueous ozone concentration was the most influential factor in the sterilization ratio. Under low aqueous ozone concentrations (less than 0.125 mg/l), the bacterial cell membranes remained intact, and the ozone was detoxified by intracellular antioxidant enzymes (e.g., superoxide dismutase and catalase). Under high aqueous ozone concentrations (more than 1 mg/l), cell membranes were damaged by the degree of peripheral electronegativity at the cell surface and the concentration of lactate dehydrogenase released into the extracellular space, and the ultrastructures of the cells were confirmed by transmission electron microscopy. Aqueous ozone penetrated the cells through leaking membranes, inactivated the enzymes, inhibited almost all the genes, and degraded the genetic materials of gDNA and total RNA, which eventually led to cell death.