检索结果-南通市图书馆

In situ synthesis and modification of calcium carbonate nanoparticles via a bobbling method

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2009年第7期52卷 924-929页

作者： ZHAO LiNa FENG JingDong wang zichen College of Chemistry Jilin Normal UniversitySiping 136000China Institute of Chemistry Jilin UniversityChangchun 130023China

Modified calcium carbonate (CaCO3) nanoparticles with cubic- and spindle-like configuration were synthesized in situ by the typical bobbling (gas-liquid-solid) method. The modifiers, such as sodium stearate, octadecyl dihydrogen phosphate (ODP) and oleic acid (OA), were used to obtain hydrophobic nanoparticles. The different modification effects of the modifiers were investigated by measuring the active ratio, whiteness and the contact angle. Moreover, transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetry analysis (TGA analysis) were employed to characterize the obtained products. A preliminary reaction mechanism was discussed. According to the results, the active ratio of CaCO3 modified by ODP was ca. 99.9% and the value of whiteness was 97.3% when the dosage of modifiers reached 2%. The contact angle was 122.25° for the CaCO3 modified in the presence of sodium stearate, ODP and OA. When modified CaCO3 was filled into PVC, the mechanical properties of products were improved greatly such as rupture intensity, pull intensity and fuse temperature. The compatibility and affinity between the modified CaCO3 nanoparticles and the organic matrixes were greatly improved.

关键词： in situ synthesis CaCO3 nanoparticles hydrophobic modifiers mechanical properties PVC

Synthesis of self-assembled needle-shaped calcium carbonate superstructures

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2010年第20期55卷 2131-2135页

作者： ZHAO LiNa FENG JingDong wang XiuYan wang zichen College of Chemistry Jilin Normal University Siping 136000 China Institute of Chemistry Jilin University Changchun 130023 China

Novel self-assembled calcium carbonate(CaCO3)crystals exhibiting the morphology of well-defined needles were synthesized by a simple precipitation reaction in the presence of octadecyl dihydrogen phosphate(ODP)as a crystal *** CaCO3 obtained by this method is hydrophobic,making it likely to be used widely in *** resulting products were characterized by powder X-ray diffraction,field emission scanning electron microscopy,Fourier transform infrared spectroscopy and contact angle *** results indicated that ODP plays an important role in determining the structure,morphology and hydrophobicity of CaCO3 crystals.

关键词：碳酸钙晶体合成水晶自组装场发射扫描电子显微镜傅立叶变换红外光谱仪粉末X射线衍射上盖针状

High-Precision Colorimetric Sensing by Dynamic Tracking of Solvent Diffusion in Hollow-Sphere Photonic Crystals

在线全文

学校读者我要写书评

暂无评论

Research 2022年第3期2022卷 397-407页

作者： Qianqian Fu Jianping Ge Chen Chen zichen wang Fan Yang Yadong Yin Department of Chemistry University of CaliforniaRiversideCaliforniaUSA CA 92521 School of Chemistry and Molecular Engineering Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesEast China Normal UniversityShanghaiChina 200062 Institute of Eco-Chongming ShanghaiChina 202162

Expensive instruments and complicated data processing are often required to discriminate solvents with similar structures and *** sensors with high selectivity,low cost,and good portability are highly desirable to simplify such detection ***,we report the fabrication of a photonic crystal sensor based on the self-assembled resorcinol formaldehyde(RF)hollow spheres to realize colorimetric sensing of polar solvents,including homologs and isomers based on the saturated diffusion *** diffusion of solvent molecules through the photonic crystal film exhibits a unique three-step diffusion profile accompanied by a dynamic color change,as determined by the physicochemical properties of the solvent molecules and their interactions with the polymer shells,making it possible to accurately identify the solvent type based on the dynamic reflection spectra or visual *** its superior selectivity and sensitivity,this single-component colorimetric sensor represents a straightforward tool for convenient solvent detection and identification.

关键词： properties. diffusion selectivity

Size Effects on the Crystallite Structure and Phase Transition in Lanthanaum-Modified Lead Titanate Nanocrystals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1994年第9期11卷 581-584页

作者： wang Xiaohui wang zichen ZHAO Muyu MENG Jinfang LI Jiangping ZOU Guangtian Department of Chemistry Jilin UniversityChangchun 130023 Department of Physics Jilin UniversityChangchun 130023

The size effects on the crystallite structure,Raman spectra as well as phase tian-sition in lanthanum-modified lead titanate Pb_(1-x)La_(x)Ti_(1-3/4x)O_(3)(x=0.14)(PLT14)nanocrystalline powders were *** results show that with decreasing grain size,the crystallite structure changes from tetragonal perovskite phase to cubic perovskite phase;the soft mode frequency at room temperature decreases,and disappears when the grain size is as small as 19nm;the phase transition temperature from ferroelectric to paraelectric shifts towards a low temperature *** phase transition in nanocrystalline PLT14 is a second order one,which is confirmed by its dielectric constant measurement.

关键词： perovskite size crystallite

Eurasian otters prefer to prey on religious released nonnative fish on the Qinghai-Tibetan Plateau

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Current Zoology 2024年第4期70卷 472-479页

作者： Qiaoyun wang Xuesong Han zichen wang Kaidan Zheng Zhengyi Dong Peng Zhang Pengfei Fan Lu Zhang School of Life Sciences Sun Yat-Sen UniversityGuangzhou 510275China State Key Laboratory of Biocontrol School of Life SciencesSun Yat-sen UniversityGuangzhou 510275China School of Life Sciences Peking UniversityBeijing 100871China Shan Shui Conservation Center Beijing100871China School of Ecology Sun Yat-sen UniversityShenzhenGuangdong 518107China

Religious wildlife release is prevalent worldwide,especially in Asia *** is one of the anthropogenic pathways to cause biological *** fish release is common on the Qinghai-Tibetan Plateau,yet few studies have assessed the influences of religious fish release on local ***,a city on the Qinghai-Tibetan Plateau,we interviewedlocal people,conducted fish trap surveys in local rivers,and exam-ined the diet of Eurasian otters Lutra lutra using a fecal DNA metabarcoding *** found that fish release started at least in 1980-1990s in *** residents released fish in large amounts and released fish were usually exotic commercial fish purchased from *** such long-term and intensive fish release activities,released fish were few in local *** the other hand,Eurasian otters mainly prey on fish and released fish accounted for~20%of relative read abundance of prey DNA in otters'diet,indicating their high preference on released *** study suggested that religious fish release may provide additional food resources for otters,whereas otters,as a top predator in local rivers,may deplete non-native fish once they were released and,therefore,reduce the probability of colonization of released fish,although further studies are required to assess otters'*** study revealed otters'diet in Yushu,providing basic information for local otter management and ***,it represents a case showing that native predators prey on religious released animals,implying a probable direction forcontrolling invasive species through nativepredator conservation.

关键词： biological invasion Buddhism Eurasian otter prey composition religious wildlife release scat DNA.

Coupling effects of tungsten and molybdenum on microstructure and stress-rupture properties of a nickel-base cast superalloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2018年第1期28卷 45-53页

作者： Tongjin Zhou Wei Feng Huibin Zhao Yu Meng Huaxia Zhang Hongsheng Ding zichen wang National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology Beijing Institute of Aeronautical Materials

In order to comprehensively understand the forming mechanism of abnormal phases solidified in a nickel-base cast superalloy with additives of tungsten and molybdenum, the coupling effects of W and Mo on the microstructure and stress-rupture properties were investigated in this paper. The results indicated that the precipitation of primary α-（W, Mo） phase depended tremendously on the amount of W and Mo addition. When the total amount of W and Mo was greater than 5.79 at%, α-（W, Mo） phase became easily precipitated in the *** increasing of Mo/W ratio, the dendrite-like α-（W, Mo） phases were apt to convert into small bars or blockylike phases at the vicinities of γ′/γ eutectic. The morphological changes of α-（W, Mo） phase can be interpreted as the non-equilibrium solidification of W and Mo in the alloy. Since the large sized α-（W, Mo） phase has detrimental effects on stress-rupture properties in as-cast conditions, secondary cracks may mainly initiate at and then propagate along the interfaces of brittle phases and soft matrix. During exposing at 1100 ℃ for 1000 h, the α-（W, Mo） phases transformed gradually into bigger and harder M;C carbide, which results in decreasing of stress-rupture properties of the alloy. Finally, the alloy with an addition of 14W-1Mo（wt%） maintained the longest stress lives at high temperatures and therefore it revealed the best microstructure stability after 1100 ℃/1000 h thermal exposure.

关键词： Superalloy Tungsten and molybdenum Cast Microstructure Stress-rupture properties

CNC NON-CONTACT MEASURING SYSTEM FOR FREEFORM SURFACE

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2002年第2期15卷 103-106页

作者： JuHua wang Wen Chen zichen Li Jian wang Hengkui Institute of Production Engineering, Zhejiang University, Hangzhou 310027, China Institute of Production Engineering Zhejiang University Hangzhou 310027

Developing CNC measuring method on the base of coordinate machine can makethe best of the hardware resource of CNC system and realize the integration of CAD/CAM/CAT. Based onthe evenly spaced parallel planes scanning, a new adaptive digitizing approach for freeform surfacenamely arc length extrapolation is put forward. By this way, the digitizing approach can be addedto the CNC system, while the system's hardware and software are not changed.

关键词： Reverse engineering Freeform surface digitalization CNC non-contactmeasurement Arc extension

A New Chirality Invertible Photoswitch:Light-Driven Axially Chiral Hydrazone Enabling Dynamic Handedness Inversion of Self-Organized Helical Superstructure

在线全文

学校读者我要写书评

暂无评论

CCS Chemistry 2024年第8期6卷 2011-2020页

作者： Ruochen Lan Jinying Bao Zhaozhong Li Zizheng wang zichen wang Qian wang Lanying Zhang Jiumei Xiao Huai Yang Institute of Advanced Materials College of Chemistry and Chemical EngineeringJiangxi Normal UniversityNanchang 330022 Beijing Advanced Innovation Center for Materials Genome Engineering School of Materials Science and EngineeringPeking UniversityBeijing 100871 School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083 Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083 Key Laboratory of Polymer Chemistry and Physics of Ministry of Education Peking UniversityBeijing 100871 School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083

Inspired by nature,dynamic self-organized helical superstructures are becoming attractive as building blocks in soft photonic crystals and advanced chiroptical ***,a chirality invertible hydrazone photoswitch,possessing high helical twisting power(HTP)was judiciously designed and *** to the photoinduced configuration changes of the hydrazone photoswitch,it displayed superior thermal stability and strikingly reversible HTP *** incorporating a novel chiral hydrazone(CH)into the liquid crystal(LC)host,a handedness invertible cholesteric liquid crystal(CLC)helical superstructure with high thermal stability and light-modulated photonic bandgap was *** inferred that the mechanism of chirality inversion of the novel CH photoswitch derived from changes in the dihedral angle between the two naphthalene rings induced by hydrazone ***,the influence of chemical structures on its photoresponsiveness was ***,the potential applications of this advanced light-driven CLC in soft photonic crystals,showing erasable and rewritable colorful patterns and chiroptical templates to induce handedness invertible circularly polarized luminescence were illustrated.

关键词： chirality inversion hydrazone photoswitch cholesteric liquid crystals dynamic photonic crystals dynamic circularly polarized luminescence

Practice and Reflections on Bilateral Local Currency Cooperation between China and Fourr ASEAN Countries

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Forex 2024年第3期 22-26页

作者： ZHANG Manjing wang zichen SAFE's Foreign Exchange Research Center

In recent years,economic and trade exchanges between China and ASEAN countries have become increasingly *** demand for local currency settlement and direct exchange has been steadily growing,highlighting the significance of strengthening bilateral cooperation in local *** this study,the authors selected four ASEAN countries,namely Singapore,Malaysia,Thailand,and Indonesia,as case *** extensively discussed the current situation of local currency settlement and transactions between China and these countries,providing valuable insights for thefurther advancement of China-ASEAN bilateral local currency cooperation.

关键词： ASEAN currency bilateral