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A simple solution route to control synthesis of Fe_3._4 nanomaterials at low temperature and their magnetic properties

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science China chemistry 2009年第7期52卷 916-923页

作者： LIU Yi1,2. CHEN Yun1, ZENG YuPing2.& WANG ShiLong3.1 department of {3. and Chemical {2., Zaozhuang {3., Zaozhuang 2.7160, China 2.Shanghai Institute of Ceramics, Chinese Academy of sciences, Shanghai 2.0050, China 3.School of Life science and Technology, Tongji {3., Shanghai 2.0092. China department of chemistry and Chemical {2. Zaozhuang University Zaozhuang China Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China School of Life science and Technology Tongji University Shanghai China

A series of nanostructured iron compounds including cubic Fe3.4 and orthorhombic FeOOH were synthesized via a facile low temperature (in the range of 60-100℃) solution method. In the whole process, the interaction between FeCl2.4H2. and methenamine (C6H12.4) was carried out through a reflux device under different reaction conditions such as temperature, solvent, and duration. The samples were detected by XRD, TEM, SAED, physical property measurement system, and Mssbauer spectroscopy, separately. The experiments showed that magnetic mixture nanoparticles had flake and rod morphologies, and cubic Fe3.4 took on grain nanostructure. Magnetism measurements indicated that the saturated magnetization of the as-obtained magnetic mixture was lower than that of the cubic magnetite. Mssbauer spectroscopy testified the sample consisting of cubic magnetite rather than γ-Fe2.3. In addition, a possible growth mechanism of cubic magnetic nanoparticles under different conditions was discussed.

关键词： magnetic nanoparticles cubic Fe3.4 oxidation-coprecipitation method reflux magnetic properties at room temperature Mssbauer spectrum

A NOVEL SECOND-ORDER TRANSITION IN ORGANIC HYBRIDS CONSISTING OF POLYMERS AND SMALL MOLECULES

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Chinese Journal of Polymer science 2001年第5期19卷 455-466页

作者： Chi-fei Wu department of chemistry and Chemical {2. Kanazawa {3. 2.40-2. Kodatsuno Kanazawa, Ishikawa 92.-8667 Japan Kanazawa university 日本

A novel transition appeared above thc glass transition temperature of chlorinated polyethylene (CPE) for binaryblends of CPE and additives such as organic small molecules or oligomers. This transition was assigned to the dissociation ofintermolecular hydrogen bonds between the polymer ard additive within the edditive rich phase. Of particular interest is thata novel pyramid crystal was observed in the annealed CPE/hindered phenol blends. Another intriguing observation is thatthese polymer/small molecule blends organized by intermolecular hydrogen bonding have several potential properties, suchas shape-memorization, self-restoration, self-adhesiveness and super damping.

关键词： Organic hybrid Second-order transition Shape memory effect Damping Self restoration

Effect of Fe metal on the growth of silicon oxide nanowires

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 317-321页

作者： Wei-long Liu1), Shu-huei Hsieh1), Ching He Chen2., and Wen-jauh Chen3. 1) department of Materials science and {2., Formosa {3., Yunlin 63.0} China Taipei 2. department of Materials {2., Pingtung {3. of science and Technology, Pingtung 912. China Taipei 3. Graduate School of Materials science, Yunlin {3. of science and Technology, Yunlin 63.0} China Taipei department of Materials science and {2. Formosa University Yunlin 632 China Taipei department of Materials engineering Pingtung University of Science and Technology Pingtung 912 China Taipei Graduate School of Materials science Yunlin University of Science and Technology Yunlin 632 China Taipei

Silicon oxide (SiOx) nanowires are generally grown on Si substrate under the catalysis of Au in N2.atmosphere at elevated temperatures. Because the price of Au metal is quite high, Fe metal is then used to replace a part of Au for catalyzing the growth of SiOx nanowires. The results show that the Fe film can be used as the diffusion barrier of Au. SiOx nanowires are grown on Au/Fe/Si substrate at 103.°C. Under the catalysis of Fe/Au, the efficiency for the growth of SiOx nanowires is promoted.

关键词： silicon oxide nanowires Au catalyst Fe substitution Si substrate

Synthesis and Characterization of a Novel pH-sensitive Complex for Drug Release

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Journal of Wuhan university of Technology(Materials science) 2010年第1期25卷 24-27页

作者：许东颖李光吉 department of Polymer science and {2. South China University of Technology

A novel pH-sensitive complex was prepared by using oxidized konjac glucomannan and 4-aminosalicylic acid （4-ASA） through glutaraldehyde as a cross-linking agent. The product was characterized by FTIR and 13. NMR spectra, and the thermogravimetric analysis was also studied. The drug release studies in vitro showed that the amount of 4-ASA released from the complex was about 4%, 56% and 17% after 12.h at pH 1.2. 6.8 and 7.4, respectively. The data demonstrate that the rate of the drug release of the complex can be more effectively controlled by pH value. The results showed that the novel pH-sensitive complex could be potentially useful for colon-targeting drug delivery system.

关键词： konjac glucomannan pH-sensitivity drug release

Effect of Limestone Powder and Fly Ash on Magnesium Sulfate Resistance of Mortar

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Journal of Wuhan university of Technology(Materials science) 2010年第4期25卷 700-703页

作者：刘数华 State Key Laboratory of Water Resources and Hydropower engineering science Wuhan University

The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain periods. The experimental results show that the strength of mortar stored in MgSO4 solution increases a little before 2. d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO4 solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca（OH）2.and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.

关键词： limestone powder fly ash mortar magnesium sulfate resistance

PROPERTIES OF POLYURETHANE ELASTOMERS BASED ON POLY (OXYETHYLENE-co-OXYTETRAMETHYLENE) DIOL

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Chinese Journal of Polymer science 2001年第4期19卷 371-376页

作者： Chen-yu Su Guang-li Zhang Hong-zhi Zhang department of Polymer science and {2. College of {3. and Molecular {2. Peking university Beijing 100871, China 北京大学北京

Polyurethane elastomers derived from 4,4 ' -methylene bis(phenyl isocyanate), butylene glycol and the low oxyethylene moiety content copolyether of tetrahydrofuran and ethylene oxide, obtained by copolymerization using heteropolyacid-ethylene oxide initiator system, were prepared. The polyurethanes exhibited an increased water absorption and much better low temperature resilience, which remained high even at a temperature of -3.degreesC, while that of polyurethane based upon poly(tetramethylene ether) glycol of the 'same molecular weight, i.e. being 2.00, and molecular weight distribution, i.e, in the range of 1.4-1.5, starts to decrease dramatically at 5 degreesC.

关键词： polyurethane poly(oxyethylene-co-oxytetramethylene) diol low temperature resilience heteropolyacid-ethylene oxide initiator system

Dynamic damage and stress-strain relations of ultra-high performance cementitious composites subjected to repeated impact

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science China(Technological sciences) 2010年第6期53卷 1520-1525页

作者： LAI JianZhong1 & SUN Wei2.1 department of Materials science and {2.,Nanjing {3. of science and Technology,Nanjing 2.0094,China 2.College of Materials science and {2.,Southeast {3.,Nanjing 2.1189,China department of Materials science and {2. Nanjing University of Science and Technology Nanjing China College of Materials science and engineering Southeast University Nanjing China

Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste *** dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity *** show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume *** stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation *** effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were *** show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.

关键词： ultra-high performance cementitious composites (UHPCC) split Hopkinson pressure bar (SHPB) repeated impact damage stress-strain

Synthesis and thermodynamic analysis of nano-La2.3

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Progress in Natural science:Materials International 2007年第7期17卷 838-844页

作者： Liu Lili~(1,2. Tang Jie~2.Li Yuxiang~1 Zhang Mei~(1**) Wang Xidong~(1,3. (1.department of Physical {3.,{2. of {3. and Technology Beijing,Beijing 100083.China 2.National Institute for Materials {3.,Segen 1-2.1,Tsukuba 3.5-0047,Japan 3.College of engineering,Beijing {2.,Beijing 100871,China) department of Physical chemistry University of Science and Technology Beijing Beijing 100083 China National Institute for Materials science Segen 1-2-1 Tsukuba 305-0047 Japan College of engineering Beijing University Beijing 100871 China

The thermodynamic parameters of La（NO3.3.nd La（OH）3.re evaluated and the thermodynamics of nano-La2.3.yn- thetic process is *** the base of thermodynamic analysis,La2.3.ano-powders are prepared by the sol-gel method and the experi- ment scheme is designed by an orthogonal *** dry-gelatin is analyzed with differential thermal analysis/thermo-gravimetric analy- sis（TGA-DTA）and X-ray diffraction *** microstructure of nano-La2.3.owders is observed by transmission dectron micro- *** synthetic parameters affecting the average grain size and dispersivity of nano-La2.3.articles are experimentally examined and *** the results indicate that nano-La2.3.articles well-dispersed are obtained and the average grain size is in the range of 2.—50 nm.

关键词： nano-La2.3 sol-gel thermodynamic analysis

Numerical simulation of air-water two-phase flow over stepped spillways

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science China(Technological sciences) 2006年第6期49卷 674-684页

作者： CHENG Xiangju1, CHEN Yongcan1 & LUO Lin2.1. department of Hydraulic engineering, Tsinghua {2., Beijing 100084, China 2. State Key Laboratory of Hydraulics and Mountain River engineering, sichuan {2., Chengdu 610065, China department of Hydraulic engineering Tsinghua University Beijing China State Key Laboratory of Hydraulics and Mountain River engineering Sichuan University Chengdu China

Stepped spillways for significant energy dissipation along the chute have gained interest; popularity among researchers; dam engineers. Due to the complexity of air-water two-phase flow over stepped spillways, the finite volume computational fluid dynamics module of the FLUENT software was used to simulate the main characteristics of the flow. Adopting the RNG k- turbulence model, the mixture flow model for air-water two-phase flow was used to simulate the flow field over stepped spillway with the PISO arithmetic technique. The numerical result successfully reproduced the complex flow over a stepped spillway of an experiment case, including the interaction between entrained air bubbles; cavity recirculation in the skimming flow regime, velocity distribution; the pressure profiles on the step surface as well. The result is helpful for understanding the detailed information about energy dissipation over stepped spillways.

关键词： stepped spillway, mixture model, RNG k-εmodel, air-water two-phase flow.