256 results on '"Fudong Wang"'
Search Results
102. CD74, a novel predictor for bronchopulmonary dysplasia in preterm infants.
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Junyan Gao, Mingfu Wu, Fudong Wang, Lijun Jiang, Rui Tian, Xueping Zhu, Shan He, Gao, Junyan, Wu, Mingfu, Wang, Fudong, Jiang, Lijun, Tian, Rui, Zhu, Xueping, and He, Shan
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- 2020
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103. Kinetics and Mechanisms of Aggregative Nanocrystal Growth
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Vernal N. Richards, Shawn P. Shields, William E. Buhro, and Fudong Wang
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Coalescence (physics) ,Ostwald ripening ,Materials science ,General Chemical Engineering ,Kinetics ,Nucleation ,Nanoparticle ,Nanotechnology ,General Chemistry ,Colloid ,symbols.namesake ,Nanocrystal ,Chemical physics ,Scientific method ,Materials Chemistry ,symbols - Abstract
The aggregative growth and oriented attachment of nanocrystals and nanoparticles are reviewed, and they are contrasted to classical LaMer nucleation and growth, and to Ostwald ripening. Kinetic and mechanistic models are presented, and experiments directly observing aggregative growth and oriented attachment are summarized. Aggregative growth is described as a nonclassical nucleation and growth process. The concept of a nucleation function is introduced, and approximated with a Gaussian form. The height (Γmax) and width (Δtn) of the nucleation function are systematically varied by conditions that influence the colloidal stability of the small, primary nanocrystals participating in aggregative growth. The nucleation parameters Γmax and Δtn correlate with the final nanocrystal mean size and size distribution, affording a potential means of achieving nucleation control in nanocrystal synthesis.
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- 2013
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104. Research on Double Price Regulations and Peak Shaving Reserve Mechanism in Coal-Electricity Supply Chain
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Hongjun Peng, Fudong Wang, and Meihua Zhou
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Mains electricity ,Article Subject ,Waste management ,Natural resource economics ,business.industry ,lcsh:Mathematics ,General Mathematics ,technology, industry, and agriculture ,General Engineering ,respiratory system ,lcsh:QA1-939 ,complex mixtures ,Boom ,respiratory tract diseases ,lcsh:TA1-2040 ,Order (exchange) ,Peaking power plant ,otorhinolaryngologic diseases ,Coal ,Electricity ,Marketization ,lcsh:Engineering (General). Civil engineering (General) ,business ,Constraint (mathematics) - Abstract
The game models were used to study the mechanism of coal-electricity price conflict under conditions of double price regulations of coal and electricity. Based on this, the peak shaving reserve mechanism was designed to probe into the countermeasures against the coal-electricity price conflicts. The study revealed that in the boom seasons of coal demand, the initiatives of the coal enterprises to supply thermal coal and the electricity enterprises to order thermal coal are reduced under conditions of double price regulations. However, under the circumstances of coal price marketization, in the boom seasons of coal demand the thermal coal price may go up obviously, the initiatives of the coal enterprises to supply thermal coal are increased, and meanwhile the initiatives of the power enterprises to order thermal coal are decreased dramatically. The transportation capacity constraint of coal supply leads to the evident decrease of the initiatives of coal enterprises for the thermal coal supply. The mechanism of peak shaving reserve of thermal coal may not only reduce the price of coal market but also increase the enthusiasm of the power enterprises to order more thermal coal and the initiatives of the coal enterprises to supply more thermal coal.
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- 2013
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105. Spectroscopic Properties of Phase-Pure and Polytypic Colloidal Semiconductor Quantum Wires
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Richard A. Loomis, Fudong Wang, and William E. Buhro
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Condensed matter physics ,Condensed Matter::Other ,Band gap ,Chemistry ,business.industry ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cadmium telluride photovoltaics ,Spectral line ,0104 chemical sciences ,Condensed Matter::Materials Science ,Semiconductor ,Extinction (optical mineralogy) ,Phase (matter) ,General Materials Science ,0210 nano-technology ,business ,Quantum ,Wurtzite crystal structure - Abstract
We report ensemble extinction and photoluminesence spectra for colloidal CdTe quantum wires (QWs) with nearly phase-pure, defect-free wurtzite (WZ) structure, having spectral line widths comparable to the best ensemble or single quantum-dot values, to the single polytypic (having WZ and zinc blende (ZB) alternations) QW values, and to those of two-dimensional quantum belts or platelets. The electronic structures determined from the multifeatured extinction spectra are in excellent agreement with the theoretical results of WZ QWs having the same crystallographic orientation. Optical properties of polytypic QWs of like diameter and diameter distribution are provided for comparison, which exhibit smaller bandgaps and broader spectral line widths. The nonperiodic WZ-ZB alternations are found to generate non-negligible shifts of the bandgap to intermediate energies between the quantum-confined WZ and ZB energies. The alternations and variations in the domain sizes result in inhomogeneous spectral line width broadening that may be more significant than that arising from the 12-13% diameter distributions within the QW ensembles.
- Published
- 2016
106. Creation of an Ultracold Gas of Ground-State DipolarNa23Rb87Molecules
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Nadia Bouloufa-Maafa, Xin Ye, Bo Lu, Romain Vexiau, Dajun Wang, Fudong Wang, Bing Zhu, Olivier Dulieu, Mingyang Guo, and Goulven Quéméner
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Condensed Matter::Quantum Gases ,Physics ,General Physics and Astronomy ,Alkali metal ,01 natural sciences ,010305 fluids & plasmas ,Dipole ,Electric dipole moment ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Molecule ,Physics::Atomic Physics ,Atomic physics ,010306 general physics ,Ground state - Abstract
A new bosonic species of ultracold alkali heteromolecule with a considerable electric dipole moment has been cooled to its vibrational ground state.
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- 2016
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107. Long-range states of the NaRb molecule near theNa(3 2S1/2)+Rb(5 2P3/2)asymptote
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Dajun Wang, Nadia Bouloufa-Maafa, Fudong Wang, Mingyang Guo, Romain Vexiau, Xiaoke Li, Olivier Dulieu, Xiaodong He, and Bing Zhu
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Physics ,Zeeman effect ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Bond-dissociation energy ,Diatomic molecule ,symbols.namesake ,0103 physical sciences ,symbols ,Atomic physics ,Asymptote ,van der Waals force ,010306 general physics ,0210 nano-technology ,Feshbach resonance ,Spectroscopy ,Hyperfine structure - Abstract
We report a high-resolution spectroscopic investigation of the long-range states of the (NaRb)-Na-23-Rb-87 molecule near its Na(3 S-2(1/2))+Rb(5 P-2(3/2)) asymptote. This study was performed with weakly bound ultracold molecules produced via magnetoassociation with an interspecies Feshbach resonance. We observed several regular vibrational series, which are assigned to the five attractive long-range states correlated with this asymptote. The vibrational levels of two of these states have sharp but complex structures due to hyperfine and Zeeman interactions. For the other states we observed significant linewidth broadenings due to strong predissociation caused by spin-orbit couplings with states correlated to the lower Na(3 S-2(1/2))+Rb(5 P-2(1/2)) asymptote. The long-range C-6 van der Waals coefficients extracted from our spectrum are in good agreement with theoretical values.
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- 2016
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108. Spectroscopic identification of tri-n-octylphosphine oxide (TOPO) impurities and elucidation of their roles in cadmium selenide quantum-wire growth
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Fudong Wang, Rui Tang, Kao, Jeff L.-F., Dingman, Sean D., and Buhro, William E.
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Cadmium -- Chemical properties ,Cadmium -- Electric properties ,Quantum chemistry -- Analysis ,Selenium -- Chemical properties ,Selenium -- Electric properties ,Chemistry - Abstract
The utility of different batches of commercially obtained tri-n-octylphosphine oxide (TOPO) solvent has introduced significant variability into the outcomes of CdSe quantum-wire syntheses. The impurity di-n-octylphosphinic acid (DOPA) is an important beneficial TOPO impurity for the reproducible growth of high-quality CdSe quantum wires.
- Published
- 2009
109. Bright Core–Shell Semiconductor Quantum Wires
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Jessica Hoy, Yi Hsin Liu, Richard A. Loomis, Fudong Wang, Lindsey K. Steinberg, Virginia L. Wayman, and William E. Buhro
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Photoluminescence ,Chemistry ,business.industry ,Nanowire ,Shell (structure) ,chemistry.chemical_element ,General Chemistry ,Sulfides ,Biochemistry ,Article ,Catalysis ,Cadmium telluride photovoltaics ,Colloid and Surface Chemistry ,Semiconductor ,Semiconductors ,Quantum dot ,Quantum Dots ,Monolayer ,Cadmium Compounds ,Optoelectronics ,Colloids ,Tellurium ,business - Abstract
Colloidal CdTe quantum wires are reported having ensemble photoluminescence efficiencies as high as 25% under low excitation-power densities. High photoluminescence efficiencies are achieved by formation of a monolayer CdS shell on the CdTe quantum wires. Like other semiconductor nanowires, the CdTe quantum wires may contain frequent wurtzite–zinc-blende structural alternations along their lengths. The present results demonstrate that the optical properties, emission-peak shape and photoluminescence efficiencies, are independent of the presence or absence of such structural alternations.
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- 2012
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110. Isolation of the Magic-Size CdSe Nanoclusters [(CdSe)13(n-octylamine)13] and [(CdSe)13(oleylamine)13]
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Richard A. Loomis, Henry W. Rohrs, Michael L. Gross, Paul J. Kowalski, Ying Zhang, Fudong Wang, Yuanyuan Wang, William E. Buhro, and Yi Hsin Liu
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Materials science ,Cadmium selenide ,Ligand ,Inorganic chemistry ,Nanoparticle ,General Medicine ,General Chemistry ,Article ,Mass Spectrometry ,Catalysis ,Nanoclusters ,chemistry.chemical_compound ,Crystallography ,chemistry ,Oleylamine ,Phase (matter) ,Cadmium Compounds ,Nanoparticles ,Lamellar structure ,Amines ,Selenium Compounds ,Stoichiometry - Abstract
The preparation, isolation, stoichiometric characterization, and dissolution of purified (CdSe)13 nanoclusters are described. We[1] and others[2] recently reported that (CdSe)13 nanoclusters were intermediates in the synthesis of CdSe quantum belts (nanoribbons). We now demonstrate that a lamellar intermediate phase[1] collected from the quantum-belt synthesis is [(CdSe)13(n-octylamine)13], the smallest, discrete, magic-size nanocluster of CdSe that has been observed.[3] Kinetic data show that free, soluble [(CdSe)13(oleylamine)13] nanoclusters are released from the insoluble [(CdSe)13(n-octylamine)13] upon ligand exchange.
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- 2012
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111. Morphology Control of Cadmium Selenide Nanocrystals: Insights into the Roles of Di-n-octylphosphine Oxide (DOPO) and Di-n-octylphosphinic Acid (DOPA)
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Fudong Wang and William E. Buhro
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Cadmium selenide ,Inorganic chemistry ,Oxide ,Nanoparticle ,General Chemistry ,Biochemistry ,Catalysis ,chemistry.chemical_compound ,Oleic acid ,Colloid and Surface Chemistry ,chemistry ,Nanocrystal ,Impurity ,Quantum dot ,Particle size ,Nuclear chemistry - Abstract
Di-n-octylphosphine oxide (DOPO) and di-n-octylphosphinic acid (DOPA), as two of impurities found in commercial tri-n-octylphosphine oxide (TOPO), generate significant differences in the outcomes of CdSe-nanocrystal (NC) syntheses. Using n-tetradecylphosphonic acid (TDPA) as the primary acid additive, quantum dots (QDs) are grown with DOPO added, whereas quantum rods (QRs) are grown in the presence of DOPA. While using oleic acid (OA) as the primary acid additive, QDs are generated and the QDs produced with DOPA exhibit larger sizes and size distributions than those produced with DOPO. 31P NMR analyses of the reaction mixtures reveal that the majority of the DOPO has been converted into DOPA and di-n-octylphosphine (DOP) with DOP being removed via evacuation over the course of Cd-precursor preparation. The origin of the puzzling differences in the shape control of CdSe NCs in the presence of DOPO and DOPA is elucidated to be the small quantity of DOPO present, which liberates DOP during NC synthesis. In t...
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- 2012
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112. Geochemistry Characteristics of Granodiorite Porphyry in the Degongniuchang Copper Deposit, Muli, Sichuan Province, China
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Dong Peng, Pengcheng Ma, Yunxi Xie, Hujie Li, Fudong Wang, and Gang Xu
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010504 meteorology & atmospheric sciences ,chemistry ,Geochemistry ,chemistry.chemical_element ,Geology ,010502 geochemistry & geophysics ,China ,01 natural sciences ,Copper ,0105 earth and related environmental sciences - Published
- 2017
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113. Colloidal GaAs quantum wires: solution-liquid-solid synthesis and quantum-confinement studies
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Angang Dong, Heng Yu, Fudong Wang, and Buhro, William E.
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Quantum chemistry -- Research ,Gallium arsenide -- Structure ,Gallium arsenide -- Electric properties ,Gallium arsenide -- Optical properties ,Bismuth -- Chemical properties ,Chemistry - Abstract
The solution-liquid-solid (SLS) mechanism is used for growing colloidal GaAs quantum wires. The GaAs quantum wire and well band gaps have scaled according to the prediction of a simple effective-mass-approximation, particle-in-a-box (EMA-PIB) model, which has estimated kinetic confinement energies of electron-hole pairs in quantum nanostructures of different shapes and confinement dimensionalities.
- Published
- 2008
114. Madouzi-type (nodular) sedimentary copper deposit associated with the Emeishan basalt
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Xiaoqing Zhu, Zhonggang Wang, and FuDong Wang
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Basalt ,Chalcocite ,Mineral ,Chalcopyrite ,Geochemistry ,chemistry.chemical_element ,Mineralogy ,engineering.material ,Copper ,Native copper ,chemistry ,visual_art ,engineering ,visual_art.visual_art_medium ,Bornite ,General Earth and Planetary Sciences ,Metasomatism ,Geology - Abstract
Ore minerals in the sedimentary-type Cu deposits in the Xuanwei Formation overlying the Emeishan basalt are dominated by copper sulfides and native copper. As the ores mostly exhibit concretionary structure, previous researchers named them the “Madouzi-type Copper Deposit”. Here the authors carried out mineralogical and isotopic studies on copper nodules in this ore deposit. The mineralogical study shows that copper nodules are composed of copper sulfides that have been cemented by ferruginous amorphous minerals, clay, and carbonaceous fragments in the modes of metasomatism and sedimentation. The nodules are preliminarily present as aggregates of gelatinous material. The isotopic analysis shows that the δ13CPDB values of anthraxolite are within the range of −24.8‰–−23.9‰, indicating that the anthraxolite is the product of sedimentary metamorphism of in-situ plants. The δ34SV-CDT values of chalcocite are within the range of 7.6‰–13.1‰, close to those (about 11‰) of Permian seawater. The δ34SV-CDT values of bornite and chalcopyrite are 21.6‰–22.2‰, similar to the sulfur isotopic composition (20‰) of marine sulfate, indicative of different sources of sulfur. The above characteristics indicate that the copper nodules were formed in such a process that Cu-bearing basalt underwent weathering-leaching and copper-bearing material was transported into waters (e.g., rivers, lakes, and swamps) and then adsorbed on clay and ferruginous amorphous mineral fragments. Then, the copper-bearing material was suspended and transported in the form of gelinite. In lake or swamp environment, it was co-deposited with sediments to form copper nodules. At later stages there occurred metasomatism and hydrothermal superimposition, followed by the replacement of chalcocite by bornite and the superimposition of chalcopyrite over bornite, finally resulting in the formation of the “Madouzi-type” nodular copper deposit.
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- 2011
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115. Preparation of Ketolactone and Bislactone [60]Fullerene Derivatives and Their Conversion into Open-Cage Fullerenes with a 12- or 15-Membered Orifice
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Jianxin Zhang, Dazhi Yang, Nana Xin, Liangbing Gan, and Fudong Wang
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chemistry.chemical_classification ,Ketone ,Fullerene ,Organic Chemistry ,Epoxide ,Peroxide ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Moiety ,Organic chemistry ,Physical and Theoretical Chemistry ,Lactone ,Derivative (chemistry) ,Body orifice - Abstract
Selective cleavage of the peroxo group in the fullerene mixed peroxide C60(O)(OOtBu)61 produces open-cage fullerenes with ketone and lactone moieties on the rim of the orifice. Photolysis of 1 results in the ketolactone derivative 2 C58(CO)-(COO)(O)(OOtBu)4 with an epoxide moiety. Thermolysis of 1 results in the formation of two other isomers, the bislactone 3 C58(COO)2(OOtBu)4 and the ketolactone 4 C58(CO)(COO)(O)(OOtBu)4 with a 1,4-dioxepin-5-one moiety. Both alcohols and amines react with one of the lactone moieties of 3 and expand the 12-membered orifice into a 15-membered orifice. Only amines react with the lactone moiety of 4 and expand the 11-membered orifice into a 12-membered orifice. Total yield of the 15-membered open-cage compound can reach 8.9 % in three steps starting from C60. The products were characterized by spectroscopic data and X-ray diffraction data.
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- 2011
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116. Solution–Liquid–Solid Growth of Semiconductor Quantum-Wire Films
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Virginia L. Wayman, Fudong Wang, William E. Buhro, and Richard A. Loomis
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Materials science ,business.industry ,Quantum wire ,Reducing atmosphere ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,Nanoparticle ,Nanotechnology ,Substrate (electronics) ,engineering.material ,Bismuth ,Semiconductor ,Coating ,chemistry ,Chemical engineering ,engineering ,General Materials Science ,business ,Deposition (law) - Abstract
We report the growth of cadmium-selenide (CdSe) quantum-wire (QW) films on a variety of substrates by the solution-liquid-solid (SLS) method. Our SLS syntheses employ size-controlled, near-monodisperse bismuth (Bi) nanoparticles (NPs) as the catalysts for QW growth, which offers several advantages over Bi NPs thermally generated from thin Bi films, including mean QW diameter control, narrow diameter distributions, small diameters in the quantum-confinement regime, and control of the QW density on the substrates. The Bi NPs are deposited on the substrates via drop casting of a Bi-NP solution and subsequently annealed in a reducing atmosphere, a key step to ensure firm attachment of the Bi NPs onto the substrates and maintenance of their catalytic activity for the QW-film growth. The QW growth density is proportional to the Bi-NP coating density, which is determined by the concentration of the Bi-NP deposition solution. Lower concentrations are used for small Bi NPs to reduce their high tendency for agglomeration and to achieve control over mean QW diameter and to produce narrow diameter distributions. Spectroscopic evidence of quantum confinement is provided. Related films of InP, InAs, and PbSe QWs are also described.
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- 2011
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117. Synthesis of [59]fullerenones through peroxide-mediated stepwise cleavage of fullerene skeleton bonds and X-ray structures of their water-encapsulated open-cage complexes
- Author
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Fudong Wang, Shaohua Huang, Liangbing Gan, Zhenshan Jia, Zhongping Jiang, Xiaobing Yang, and Zheming Wang
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Chemical synthesis -- Analysis ,Photolysis -- Analysis ,Nuclear magnetic resonance spectroscopy -- Analysis ,Chemistry - Abstract
The synthesis of [59]fulleroids with 18- and 19-membered-ring orifaces is described by using multistep chemical reactions starting from the fullerene hexaadduct [C.sub.60][(O[O.sup.t]Bu).sub.6]. The cage-opened fullerene derivatives are excellent molecular water traps and have formed water-encapsulated complexes efficiently.
- Published
- 2007
118. Determination of the rod-wire transition length in colloidal indium phosphide quantum rods
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Fudong Wang and Buhro, William E.
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Indium -- Chemical properties ,Indium -- Optical properties ,Photoluminescence -- Research ,Quantum electrodynamics -- Research ,Semiconductors -- Research ,Chemistry - Abstract
A new approach for determining the rod-wire transition length of the colloidal indium phosphide (InP) quantum rods (QRs) is discussed.
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- 2007
119. Spectroscopic properties of colloidal indium phosphide quantum wires
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Fudong Wang, Heng Yu, Jingbo Li, Qingling Hang, Dmitry Zemlyanov, Gibbons, Patrick C., Lin-Wang Wang, Janes, David B., and Buhro, William E.
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Colloids -- Research ,Indium -- Chemical properties ,Indium -- Optical properties ,Photoluminescence -- Research ,Quantum theory -- Research ,Chemistry - Abstract
The various spectroscopic properties of the colloidal indium phosphide quantum wires are discussed. These wires are found to have extremely low photoluminescence efficiencies.
- Published
- 2007
120. An Easy Shortcut Synthesis of Size-Controlled Bismuth Nanoparticles and Their Use in the SLS Growth of High-Quality Colloidal Cadmium Selenide Quantum Wires
- Author
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Fudong Wang and William E. Buhro
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Luminescence ,Materials science ,Inorganic chemistry ,chemistry.chemical_element ,Nanoparticle ,Absorption ,Bismuth ,Catalysis ,Biomaterials ,Colloid ,chemistry.chemical_compound ,Quality (physics) ,Cadmium Compounds ,General Materials Science ,Particle Size ,Selenium Compounds ,Quantum ,Cadmium selenide ,Nanowires ,Spectrum Analysis ,General Chemistry ,Bismuth nanoparticles ,Solutions ,chemistry ,Chemical engineering ,Nanoparticles ,Biotechnology - Abstract
An easy shortcut synthesis of thermally stable, near-monodisperse Bi nanoparticles from BiCl(3) and Na[N(SiMe(3))(2)] is described. The diameters of the Bi nanoparticles are controlled in the range of 4-29 nm by varying the amounts of BiCl(3) and Na[N(SiMe(3))(2)] employed. Standard deviations in their diameter distributions are 5-15% of the mean diameters, consistent with near monodispersity. These Bi nanoparticles are shown to be the best currently available catalysts for the solution-liquid-solid (SLS) growth of high-quality CdSe quantum wires.
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- 2010
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121. Solution-liquid-solid growth of semiconductor nanowires
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Fudong Wang, Angang Dong, Jianwei Sun, Rui Tang, Heng Yu, and Buhro, William E.
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Chemical synthesis -- Analysis ,Semiconductor device ,Chemistry - Abstract
The solution-liquid-solid (SLS) mechanism is developed into a synthetic method for semiconductor nanowires with the achievement of purposeful control of diameters and diameter distributions. The SLS method proves to be useful in producing the smallest nanowire diameters and for variation and control of surface litigation.
- Published
- 2006
122. The Trouble with TOPO; Identification of Adventitious Impurities Beneficial to the Growth of Cadmium Selenide Quantum Dots, Rods, and Wires
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William E. Buhro, Fudong Wang, and Rui Tang
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Magnetic Resonance Spectroscopy ,Inorganic chemistry ,Oxide ,Bioengineering ,Nanotechnology ,law.invention ,chemistry.chemical_compound ,Organophosphorus Compounds ,Microscopy, Electron, Transmission ,law ,Impurity ,Quantum Dots ,Cadmium Compounds ,General Materials Science ,Crystallization ,Selenium Compounds ,Nanotubes ,Cadmium selenide ,Nanowires ,Mechanical Engineering ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,Condensed Matter Physics ,Solvent ,Models, Chemical ,chemistry ,Nanocrystal ,Quantum dot ,Solvents ,Nanoparticles ,Lysophospholipids - Abstract
Tri-n-octylphosphine oxide (TOPO) is a commonly used solvent for nanocrystal synthesis. Commercial TOPO samples contain varying amounts of phosphorus-containing impurities, some of which significantly influence nanocrystal growth. Consequently, nanocrystal syntheses often give irreproducible results with different batches of TOPO solvent. In this study, we identify TOPO impurities by (31)P NMR, and correlate their presence with the outcomes of CdSe nanocrystal syntheses. We subsequently add the active impurity species, one by one, to purified TOPO to confirm their influence on nanocrystal syntheses. In this manner, di-n-octylphosphine oxide (DOPO) is shown to assist CdSe quantum-dot growth; di-n-octylphosphinic acid (DOPA) and mono-n-octylphosphinic acid (MOPA) are shown to assist CdSe quantum-rod growth, and DOPA is shown to assist CdSe quantum-wire growth. (The TOPO impurity n-octylphosphonic acid, OPA, has been previously shown to assist quantum-rod growth.) The beneficial impurities are prepared on multigram scales and can be added to recrystallized TOPO to provide reproducible synthetic results.
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- 2008
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123. The Scaling of the Effective Band Gaps in Indium−Arsenide Quantum Dots and Wires
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Patrick C. Gibbons, Jeffrey M. Pietryga, Heng Yu, Sohee Jeong, Jennifer A. Hollingsworth, Fudong Wang, and William E. Buhro
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Models, Molecular ,Photoluminescence ,Materials science ,Macromolecular Substances ,Surface Properties ,Band gap ,Molecular Conformation ,General Physics and Astronomy ,Scaling dimension ,Indium ,Arsenicals ,Spectral line ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Materials Testing ,Quantum Dots ,Nanotechnology ,Computer Simulation ,General Materials Science ,Particle Size ,Scaling ,Condensed matter physics ,business.industry ,Electric Conductivity ,General Engineering ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Nanostructures ,Semiconductor ,Models, Chemical ,chemistry ,Quantum dot ,Indium arsenide ,Crystallization ,business - Abstract
Colloidal InAs quantum wires having diameters in the range of 5-57 nm and narrow diameter distributions are grown from Bi nanoparticles by the solution-liquid-solid (SLS) mechanism. The diameter dependence of the effective band gaps (DeltaE(g)s) in the wires is determined from photoluminescence spectra and compared to the experimental results for InAs quantum dots and rods and to the predictions of various theoretical models. The DeltaE(g) values for InAs quantum dots and wires are found to scale linearly with inverse diameter (d(-1)), whereas the simplest confinement models predict that DeltaE(g) should scale with inverse-square diameter (d(-2)). The difference in the observed and predicted scaling dimension is attributed to conduction-band nonparabolicity induced by strong valence-band-conduction-band coupling in the narrow-gap InAs semiconductor.
- Published
- 2008
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124. Size- and Shape-Controlled Synthesis of Bismuth Nanoparticles
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Patrick C. Gibbons, Heng Yu, Rui Tang, Fudong Wang, and William E. Buhro
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chemistry.chemical_classification ,Reaction conditions ,Range (particle radiation) ,Materials science ,General Chemical Engineering ,Nanoparticle ,Nanotechnology ,General Chemistry ,Polymer ,Bismuth nanoparticles ,Shape control ,Pulmonary surfactant ,Chemical engineering ,chemistry ,Materials Chemistry ,Nanorod - Abstract
Near-monodisperse Bi dots in the diameter range of 3−115 nm are synthesized by a simple, solution-based one-step approach by varying the amounts of Bi[N(SiMe3)2]3, Na[N(SiMe3)2], and a polymer surfactant, poly(1-hexadecene)0.67-co-(1-vinylpyrrolidinone)0.33, employed. The reaction conditions are further modified to produce Bi nanorods and nanoplates. Alternatively, near-monodisperse Bi dots in the diameter range of 30−45 nm are synthesized by a secondary-addition technique. With a slight modification of this technique, nanoribbons are obtained. The roles of polymer and Na[N(SiMe3)2] in the size and shape control of these Bi nanoparticles are discussed.
- Published
- 2008
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125. Smooth control for hybrid electric vehicle based on the Pontryagin's Minimum Principle and the observer
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Juanjuan, Song, primary, Xinhao, Yang, additional, Ze, Li, additional, and Fudong, Wang, additional
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- 2017
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126. Selective preparation of oxygen-rich [60]fullerene derivates by stepwise addition of tert-butylperoxy radical and further functionalization of the Fullerene mixed peroxides
- Author
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Shaoohua Huang, Zuo Xioa, Fudong Wang, Liangbing Gan, and Xiang Zhang; Xiangqing Hu; Shiwei, Zhang; Mujian Lu; Qinqi Pan; Li Xu
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Organic compounds -- Synthesis ,Organic compounds -- Research ,Buckminsterfullerene -- Research ,Chemical reactions -- Research ,Hydrogen peroxide -- Research ,Biological sciences ,Chemistry - Abstract
The reaction between tert-butyl hydroperoxide and C60 under various conditions and the isolation of several key intermediates is reported. The unique cyclopentadiene mode of fullerene reactions are reported for the successful preparation of several fullerene multi-adducts.
- Published
- 2004
127. Role of Molecular Surface Passivation in Electrical Transport Properties of InAs Nanowires
- Author
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David B. Janes, Eric A. Stach, Dmitri Y. Zemlyanov, Patrick D. Carpenter, Qingling Hang, William E. Buhro, Fudong Wang, and Dmitri N. Zakharov
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Electron mobility ,Condensed matter physics ,Passivation ,Chemistry ,Mechanical Engineering ,Fermi level ,Nanowire ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Subthreshold slope ,symbols.namesake ,X-ray photoelectron spectroscopy ,symbols ,General Materials Science ,Field-effect transistor ,Surface states - Abstract
The existence of large densities of surface states on InAs pins the surface Fermi level above the conduction band and also degrades the electron mobility in thin films and nanowires. Field effect transistors have been fabricated and characterized in the "as fabricated" state and after surface passivation with 1-octadecanethiol (ODT). Electrical characterization of the transistors shows that the subthreshold slope and electron mobility in devices passivated with ODT are superior to the respective values in unpassivated devices. An X-ray photoelectron spectroscopy study of ODT passivated undoped InAs nanowires indicates that sulfur from ODT is bonded to In on the InAs nanowires. Simulations using a two-dimensional device simulator (MEDICI) show that the improvements in device performance after ODT passivation can be quantified in terms of a decrease of interface trap electron donor states, shifts in fixed interfacial charge, and changes in body and surface mobilities.
- Published
- 2007
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128. Spectroscopic Properties of Colloidal Indium Phosphide Quantum Wires
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David B. Janes, Heng Yu, Lin-Wang Wang, Qingling Hang, Fudong Wang, Jingbo Li, Dmitry Zemlyanov, Patrick C. Gibbons, and William E. Buhro
- Subjects
Photoluminescence ,Absorption spectroscopy ,Passivation ,business.industry ,Band gap ,General Chemistry ,Biochemistry ,Catalysis ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Quantum dot ,Etching ,Indium phosphide ,Optoelectronics ,business ,Luminescence - Abstract
Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photooxidation, without a significant influence on quantum-wire photoluminescence. However, photooxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.
- Published
- 2007
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129. Solution−Liquid−Solid (SLS) Growth of ZnSe−ZnTe Quantum Wires having Axial Heterojunctions
- Author
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William E. Buhro, Tyrone L. Daulton, Angang Dong, and Fudong Wang
- Subjects
Condensed Matter::Materials Science ,Condensed matter physics ,Chemistry ,Mechanical Engineering ,General Materials Science ,Bioengineering ,Heterojunction ,General Chemistry ,Liquid solid ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Quantum - Abstract
Heterostructured ZnSe-ZnTe quantum wires are grown by the solution-liquid-solid (SLS) mechanism. The nature of the axial or radial heterostructure obtained is strongly influenced by the growth sequence and related synthetic conditions. Compositionally graded ZnSe(x)Te(1-x) wires, ZnSe-ZnTe axial heterostructures containing a ZnSe(x)Te(1-x) transitional segment, ZnSe-ZnTe wires with sharp axial heterojunctions, and radial core-shell ZnSe-ZnTe quantum wires have been selectively prepared. The axial and radial quantum-wire heterostructures are characterized microscopically and spectroscopically.
- Published
- 2007
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130. Bound 1D Excitons in Single CdSe Quantum Wires
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Rui Tang, Richard A. Loomis, William E. Buhro, Virginia L. Wayman, Paul J. Morrison, and Fudong Wang
- Subjects
Materials science ,Photoluminescence ,business.industry ,Exciton ,chemistry.chemical_element ,Molecular physics ,Bismuth ,chemistry.chemical_compound ,chemistry ,Electric field ,Electrode ,Optoelectronics ,General Materials Science ,Charge carrier ,Physical and Theoretical Chemistry ,Thin film ,business ,Trioctylphosphine oxide - Abstract
Photogenerated electron-hole pairs are observed to be bound as 1D excitons in CdSe quantum wires (QWs) at room temperature. Microscopy experiments performed on dilute samples of CdSe QWs prepared on coverslips with patterned electrodes reveal that there is no change in either the overall photoluminescence (PL) intensity or the distribution of the PL intensity with the application of an external electric field. Changes in the PL intensity, and thus evidence for separate charge carriers within the QWs, are observed only for concentrated samples. In these concentrated samples, a thin film of other compounds, including trioctylphosphine oxide and a bismuth salt formed in the synthesis, is observed to encompass the QWs. The separate charge carriers that influence the PL intensity are attributed to the other compounds in the sample.
- Published
- 2015
131. Coherent spin-mixing dynamics in thermalRb87spin-1 and spin-2 gases
- Author
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Zhi-Fang Xu, Bing Zhu, Xiaodong He, Xiaoke Li, Fudong Wang, and Dajun Wang
- Subjects
Condensed Matter::Quantum Gases ,Physics ,education.field_of_study ,Spinor ,Condensed matter physics ,Population ,Equations of motion ,Atomic and Molecular Physics, and Optics ,symbols.namesake ,Ferromagnetism ,Boltzmann constant ,symbols ,Wigner distribution function ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,education ,Spin-½ - Abstract
We study the nonequilibrium coherent spin-mixing dynamics in ferromagnetic spin-1 and antiferromagnetic spin-2 thermal gases of ultracold $^{87}\mathrm{Rb}$ atoms. Long-lasting spin population oscillations with magnetic-field-dependent resonances are observed in both cases. Our observations are well reproduced by Boltzmann equations of the Wigner distribution function. Compared to the equation of motion of spinor Bose-Einstein condensates, the only difference here is a factor-of-2 increase in the spin-dependent interaction, which is confirmed directly in the spin-2 case by measuring the relation between the oscillation amplitude and the sample's density.
- Published
- 2015
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132. Preliminary Discussion on Comprehensive Utilization of Tailings
- Author
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Zengsheng Li, Kunyue Ling, Xiao-Hui Sun, Zhonggang Wang, Xiaoqing Zhu, Fudong Wang, and Tao Han
- Subjects
Engineering ,Mining engineering ,Recovery rate ,business.industry ,Emerging technologies ,food and beverages ,Sedimentary rock ,business ,Tailings ,Mineral formation ,Natural (archaeology) - Abstract
The study on the tailings’ comprehensive utilization is mainly concentrated in minerals in the past, which means we need to use all kinds of research methods and results that we use in the mineralogy nowadays. Maybe we can break away from the research bondage of the modern mineral technology, tracing back to the genesis of the mineral deposits from the genesis of mineral formation, especially some sedimentary deposits, which we can call “natural metallurgical field,” so that we can probably get some new technologies and methods of the tailings’ comprehensive utilization. On the other hand, after re-understanding of the varieties of deposit types and the occurrence states of metal elements, we can select the corresponding technology to recover associated components according to different types of deposits tailings, which will maximize the recovery rate of associated components.
- Published
- 2015
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133. Multiperiod Coordination Models of Coal-Electricity Supply Chain with Double Price Regulations
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Fudong Wang, Hongjun Peng, and Meihua Zhou
- Subjects
Mains electricity ,Article Subject ,business.industry ,Supply chain ,lcsh:Mathematics ,technology, industry, and agriculture ,Game models ,Economic shortage ,respiratory system ,lcsh:QA1-939 ,Boom ,complex mixtures ,respiratory tract diseases ,Chain (algebraic topology) ,Modeling and Simulation ,otorhinolaryngologic diseases ,Coal ,Electricity ,business ,Industrial organization - Abstract
Using game models, we study multiperiod coordination contract and model of coal-electricity supply chain under the condition of double price regulations to alleviate the price conflicts of coal and electricity enterprises. The study reveals that, in boom seasons of coal demand, the multiperiod coordination mechanism may not only reduce the price of thermal coal but also increase the fulfillment rate of thermal coal. Meanwhile, the ordering quantity of thermal coal is increased and the shortage probability of electricity supply is decreased. Thereby, the conflicts between coal and electricity are also alleviated effectively.
- Published
- 2015
134. Lewis Acid Promoted Preparation of Isomerically Pure Fullerenols from Fullerene Peroxides C60(OOt-Bu)6 and C60(O)(OOt-Bu)6
- Author
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Shaohua Huang, Zuo Xiao, Jiang Zhou, Shiwei Zhang, Fudong Wang, Zhipeng Yao, Liangbing Gan, Zhenshan Jia, and Gu Yuan
- Subjects
Fullerene derivatives ,Organic peroxide ,Reaction mechanism ,Fullerene ,Spectrum Analysis ,Organic Chemistry ,General Medicine ,Crystallography, X-Ray ,Heterolysis ,Chemical synthesis ,Medicinal chemistry ,Chemical correlation ,Peroxides ,chemistry.chemical_compound ,Isomerism ,chemistry ,Bromide ,X-ray crystallography ,Organic chemistry ,Fullerenes ,Lewis acids and bases - Abstract
Fullerene mixed peroxides C60(t-BuOO)6 and C60(O)(t-BuOO)6 react with Lewis acids to form various fullerenols through the partial fragmentation of t-BuOO groups. Two monohydroxyl fullerenols with the general formula C60(OH)(t-BuOO)5 and six monohydroxyl fullerenols with the general formula C60(O)(OH)(t-BuOO)5 were prepared, which are essentially the same except the location of the OH group. An additional reaction of the monohydroxyl fullerenols gave bis- and trishydroxyl fullerenols. Single-crystal X-ray structures have been obtained for the two monohydroxyl fullerenols. Other compounds are characterized by chemical correlation and their spectroscopic data. Cuprous bromide could protect the most reactive t-BuOO group from being attacked by stronger Lewis acids. The proposed mechanism mainly involves Lewis acid induced heterolysis of the peroxo O-O bond.
- Published
- 2006
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135. Regiochemistry of [70]Fullerene: Preparation of C70(OOtBu)n (n = 2, 4, 6, 8, 10) through Both Equatorial and Cyclopentadienyl Addition Modes
- Author
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Shaohua Huang, Fudong Wang, Jiang Zhou, Mujian Lu, Liangbing Gan, Zuo Xiao, Jinqi Pan, and Gu Yuan
- Subjects
Reaction mechanism ,Fullerene ,Stereochemistry ,Chemistry ,Radical ,Organic Chemistry ,Molecular Conformation ,Regioselectivity ,Stereoisomerism ,Cyclopentanes ,Chemical synthesis ,Adduct ,Crystallography ,Cyclopentadienyl complex ,Molecule ,Fullerenes - Abstract
[reaction: see text] tert-Butylperoxy radicals add to [70]fullerene to form a mixture of adducts C(70)(OO(t)()Bu)(n)() (n = 2, 4, 6, 8, 10). Four isomers were isolated for the bis-adduct with the two tert-butylperoxo groups attached at 1,2-, 5,6-, 7,23-, and 2,5-positions, respectively. Two isomers were isolated for the tetrakis-adduct with the tert-butylperoxo groups located along the equator in C(s)() symmetry and on the side in C(1) symmetry, respectively. Similarly, two isomers were isolated for the hexakis-adducts with a structure related to the tetrakis-adducts, one of which has the cyclopentadienyl substructure. No isomer was detected for the octakis- and decakis-adducts. The C(s)()-symmetric octakis- and C(2)-symmetric decakis-adducts have all the tert-butylperoxo groups located along the equator. The decakis-adduct is the major product under optimized conditions. The compounds were characterized by their spectroscopic data. Chemical correlation through further addition of tert-butylperoxy radicals to isolated pure derivatives confirmed the structure assignment. Mechanisms of the tert-butylperoxy radical addition to C(70) follow two pathways: equatorial addition along the belt and cyclopentadienyl addition on the side.
- Published
- 2005
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136. Conformational Role of Xanthan Gum in its Interaction with Guar Gum
- Author
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Z. Sun, Ya-Jane Wang, and Fudong Wang
- Subjects
chemistry.chemical_classification ,Conformational change ,Guar gum ,Intrinsic viscosity ,Guar ,Viscometer ,engineering.material ,Polysaccharide ,chemistry ,Polymer chemistry ,medicine ,engineering ,Biopolymer ,Xanthan gum ,Food Science ,medicine.drug - Abstract
: Ubbelohde viscometry, texture analysis, and centrifugation were used to investigate the effects of chain conformational changes of xanthan or deacetylated xanthan gum on its interaction with guar gum. Guar gum was not effective in denaturing xanthan gum when the xanthan helical structure was stabilized by salt. The intrinsic viscosities of deacetylated xanthan and guar blends were higher than those calculated from the weight averages of the 2. Conformational change was not observed for deacetylated xanthan, presuming deacetylated xanthan was in the exact conformation for guar to bind so that the most stable heterotypic structure between deacetylated xanthan and guar was formed directly, thus the strongest interaction was observed between deacetylated xanthan and guar.
- Published
- 2002
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137. Properties and Structures of Flours and Starches from Whole, Broken, and Yellowed Rice Kernels in a Model Study
- Author
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Linfeng Wang, Ya-Jane Wang, Fudong Wang, James Patindol, and Donya Shephard
- Subjects
chemistry.chemical_classification ,genetic structures ,Starch ,Model study ,Organic Chemistry ,Broken rice ,food and beverages ,Polysaccharide ,Protein content ,chemistry.chemical_compound ,chemistry ,Amylose ,Botany ,Postharvest ,Food science ,Chemical composition ,Food Science - Abstract
The objective of this study was to compare the structure and properties of flours and starches from whole, broken, and yellowed rice kernels that were broken or discolored in the laboratory. Physicochemical properties including pasting, gelling, thermal properties, and X-ray diffraction patterns were determined. Structure was elucidated using high-performance size-exclusion chromatography (HPSEC) and high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The yellowed rice kernels contained a slightly higher protein content and produced a significantly lower starch yield than did the whole or broken rice kernels. Flour from the yellowed rice kernels had a significantly higher pasting temperature, higher Brabender viscosities, increased damaged starch content, reduced amylose content, and increased gelatinization temperature and enthalpy compared with flours from the whole or the broken rice kernels. However, all starches showed similar pasting, gelling, ther...
- Published
- 2002
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138. [Untitled]
- Author
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Jing Liu, Fudong Wang, Yan Gao, Jie Xu, and Li Decai
- Subjects
Materials science ,Mechanics of Materials ,Scanning electron microscope ,Mechanical Engineering ,Ultimate tensile strength ,Thermal decomposition ,General Materials Science ,Thermal stability ,Composite material ,Glass transition ,Hybrid material ,Polyimide ,Sol-gel - Abstract
A new class of silica/polyimide nanocomposites was successfully prepared by the sol-gel reaction, tetraethoxysilane, (TEOS), was hydrolyzed by the water released from imidization at low and high temperature. Silica particles with diameter of around 30–50 nm were observed in the hybrid films by scanning electron microscopy. The flame retardance, decomposition temperature and glass transition temperature of the film increased with increasing silica content. The tensile strength increased slightly while the elongation at break of the films decreased with increasing silica content.
- Published
- 2002
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- View/download PDF
139. Two-dimensional semiconductor nanocrystals: properties, templated formation, and magic-size nanocluster intermediates
- Author
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Yi Hsin Liu, Yuanyuan Wang, Paul J. Morrison, Richard A. Loomis, Fudong Wang, and William E. Buhro
- Subjects
Materials science ,business.industry ,Exciton ,Quantum wire ,Nanowire ,Charge (physics) ,Nanotechnology ,General Medicine ,General Chemistry ,Electron ,Semiconductor ,Nanocrystal ,business ,Quantum - Abstract
CONSPECTUS: Semiconductor nanocrystals having an extended length dimension and capable of efficiently transporting energy and charge would have useful applications in solar-energy conversion and other emerging technologies. Pseudocylindrical semiconductor nanowires and quantum wires are available that could potentially serve in this role. Sadly, however, their defective surfaces contain significant populations of surface trap sites that preclude efficient transport. The very large surface area of long wires is at least part of the problem. As electrons, holes, and excitons migrate along a nanowire or quantum wire, they are exposed to an extensive surface and to potentially large numbers of trap sites. A solution to this dilemma might be found by identifying "long" semiconductor nanocrystals of other morphologies that are better passivated. In this Account, we discuss a newly emerging family of flat semiconductor nanocrystals that have surprising characteristics. These thin, flat nanocrystals have up to micrometer-scale (orthogonal) lateral dimensions and thus very large surface areas. Even so, their typical photoluminescence efficiencies of 30% are astonishingly high and are 2 orders of magnitude higher than those typical of semiconductor quantum wires. The very sharp emission spectra of the pseudo-two-dimensional nanocrystals reflect a remarkable uniformity in their discrete thicknesses. Evidence that excitons are effectively delocalized and hence transported over the full dimensions of these nanocrystals has been obtained. The excellent optical properties of the flat semiconductor nanocrystals confirm that they are exceptionally well passivated. This Account summarizes the two synthetic methods that have been developed for the preparation of pseudo-two-dimensional semiconductor nanocrystals. A discussion of their structural features accounts for their discrete, uniform thicknesses and details the crystal-lattice expansions and contractions they exhibit. An analysis of their optical properties justifies the sharp photoluminescence spectra and high photoluminescence efficiencies. Finally, a bilayer mesophase template pathway is elucidated for the formation of the nanocrystals, explaining their flat morphologies. Magic-size nanocluster intermediates are found to be potent nanocrystal nucleants, allowing the synthesis temperatures to be decreased to as low as room temperature. The potential of these flat semiconductor nanocrystals in the form of nanoribbons or nanosheets for long-range energy and charge transport appears to be high.
- Published
- 2014
140. A survey of personalized recommendation integrated with social networks
- Author
-
Fudong Wang and Bing Xue
- Subjects
World Wide Web ,Computer science - Published
- 2014
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141. Mid-Infrared Emitting Lead Selenide Nanocrystal Quantum Dots
- Author
-
Fudong Wang, William E. Buhro, Jennifer A. Hollingsworth, and Jeffrey M. Pietryga
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Nanocrystal ,business.industry ,Quantum dot ,Mid infrared ,Optoelectronics ,business ,Lead selenide - Published
- 2014
- Full Text
- View/download PDF
142. ChemInform Abstract: Kinetics and Mechanisms of Aggregative Nanocrystal Growth
- Author
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Shawn P. Shields, Fudong Wang, Vernal N. Richards, and William E. Buhro
- Subjects
Ostwald ripening ,symbols.namesake ,Colloid ,Nanocrystal ,Chemical physics ,Chemistry ,Scientific method ,Kinetics ,symbols ,Nucleation ,Nanoparticle ,General Medicine - Abstract
The aggregative growth and oriented attachment of nanocrystals and nanoparticles are reviewed, and they are contrasted to classical LaMer nucleation and growth, and to Ostwald ripening. Kinetic and mechanistic models are presented, and experiments directly observing aggregative growth and oriented attachment are summarized. Aggregative growth is described as a nonclassical nucleation and growth process. The concept of a nucleation function is introduced, and approximated with a Gaussian form. The height (Γmax) and width (Δtn) of the nucleation function are systematically varied by conditions that influence the colloidal stability of the small, primary nanocrystals participating in aggregative growth. The nucleation parameters Γmax and Δtn correlate with the final nanocrystal mean size and size distribution, affording a potential means of achieving nucleation control in nanocrystal synthesis.
- Published
- 2014
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143. Study of xanthan gum/waxy corn starch interaction in solution by viscometry
- Author
-
Ya-Jane Wang, Fudong Wang, and Z. Sun
- Subjects
chemistry.chemical_classification ,Waxy corn ,biology ,Starch ,General Chemical Engineering ,Intrinsic viscosity ,Viscometer ,General Chemistry ,Polysaccharide ,biology.organism_classification ,Viscosity ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Polymer chemistry ,medicine ,Thickening agent ,Xanthan gum ,Food Science ,medicine.drug - Abstract
The objective of the study was to investigate the molecular interactions of xanthan gum and waxy corn starch in a ternary system. Solutions of xanthan gum/(waxy corn starch) blends dissolved in a mixed solvent of 90% DMSO/10% H2O (v/v) were studied by means of viscometry as a function of total polymer concentration and composition. The classical Huggins equation, ηsp/C=[η]+bC, which expresses the specific viscosity (ηsp) of a polymer as a function of the concentration C, was found to be suitable for all blends in the dilute system. The intrinsic viscosity ([η]) and Huggins parameter b of the blends increased with the increase of xanthan fraction in the blends. Meanwhile, the addition of xanthan gum also dramatically lowered the overlap concentration (C*) of the blends. The results indicate that xanthan gum is a good thickener, and xanthan gum and waxy corn starch are attracted to each other in the solution under study.
- Published
- 2001
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- View/download PDF
144. Active catalyst for the hydrodechlorination of perchlorobenzene
- Author
-
Nan Sun, Fudong Wang, Shijian Liao, Yan Gao, and Daorong Yu
- Subjects
Polymers and Plastics ,Hydrogen ,General Chemical Engineering ,Catalyst support ,chemistry.chemical_element ,General Chemistry ,Biochemistry ,Catalysis ,chemistry.chemical_compound ,Polyvinyl pyrrolidone ,chemistry ,Materials Chemistry ,Environmental Chemistry ,Organic chemistry ,Benzene ,Bimetallic strip ,Palladium - Abstract
Palladium catalysts have been used in the hydrodechlorination of perchlorobenzene under mild conditions. PdCl 2 is not very active for this reaction. However, when PdCl 2 is supported on PVP (polyvinyl pyrrolidone), it exhibits a high activity. Pd–Co supported on PVP displays a bimetallic synergic effect and gives higher catalytic activity. The catalytic activity can be increased further by using NaBH 4 to reduce the catalyst instead of H 2 prior to use.
- Published
- 2000
- Full Text
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145. Preparation and characteristics of nonflammable polyimide materials
- Author
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Yan Gao, Fudong Wang, Jing Liu, and Ming Wu
- Subjects
Materials science ,Polymers and Plastics ,Sem analysis ,Interfacial adhesion ,General Chemistry ,humanities ,Surfaces, Coatings and Films ,Sulfone ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Thermal stability ,Silica nanocomposite ,Composite material ,Dispersion (chemistry) ,Polyimide ,Fire retardant - Abstract
The thermal and flame-retardant properties of homo- and copolyimides were evaluated. Those containing sulfone linkages in the backbone were found to be more flame retardant. Both properties were dependent on the composition. A polyimide/ silica nanocomposite was obtained through sol- gel processing. The effects of the addi- tion of silica on the dispersion, interfacial adhesion, fire resistance, mechanical prop- erties, and thermal stability of the composites were investigated. SEM analysis showed a good dispersion of silica with a diameter of 50 -300 nm in the organic matrices. The addition of silica increased the fire retardancy and mechanical properties of the com- posites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 384 -389, 2000
- Published
- 2000
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- View/download PDF
146. Wireless granary temperature measurement node with function of low voltage detection
- Author
-
Fudong, Wang, primary, Zhongfeng, Wang, additional, Ligang, Li, additional, Jianlong, Huang, additional, and Qian, Wang, additional
- Published
- 2016
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147. Selective hydrogenation of nitrobenzene top-Aminophenol by the polymer-supported palladium-based mono- and bimetallic catalyst
- Author
-
Shijian Liao, Daorong Yu, Yan Gao, and Fudong Wang
- Subjects
P-Aminophenol ,Inorganic chemistry ,chemistry.chemical_element ,Catalysis ,Nitrobenzene ,chemistry.chemical_compound ,Aniline ,chemistry ,Transition metal ,Polymer chemistry ,Physical and Theoretical Chemistry ,Selectivity ,Bimetallic strip ,Palladium - Abstract
In acidic reaction medium, polymer-supported monometallic palladium catalyst, PVP-PdCl2 [(PVP=poly(N-vinyl-pyrrolidone)], is used to catalyze the hydrogenation of nitrobenzene top-aminophenol and aniline. The addition of a second transition metal compound or a very small amount of 2-mercaptopyrimidine gives rise to an increase in the selectivity forp-aminophenol.
- Published
- 1998
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148. The Magic-Size Nanocluster (CdSe)
- Author
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Yuanyuan, Wang, Ying, Zhang, Fudong, Wang, Daryl E, Giblin, Jessica, Hoy, Henry W, Rohrs, Richard A, Loomis, and William E, Buhro
- Subjects
Article - Abstract
Reaction of Cd(OAc)2·2H2O and selenourea in primary-amine/secondary-amine cosolvent mixtures affords crystalline CdSe quantum platelets at room temperature. Their crystallinity is established by X-ray diffraction analysis (XRD), high-resolution transmission electron microscopy (TEM), and their sharp extinction and photoluminescence spectra. Reaction monitoring establishes the magic-size nanocluster (CdSe)34 to be a key intermediate in the growth process, which converts to CdSe quantum platelets by first-order kinetics with no induction period. The results are interpreted to indicate that the critical crystal-nucleus size for CdSe under these conditions is in the range of (CdSe)34 to (CdSe)68. The nanocluster is obtained in isolated form as [(CdSe)34(n-octylamine)16(di-n-pentylamine)2], which is proposed to function as crystal nuclei that may be stored in a bottle.
- Published
- 2013
149. Observation of Feshbach resonances between ultracold Na and Rb atoms
- Author
-
Dajun Wang, Eberhard Tiemann, Dezhi Xiong, Fudong Wang, and Xiaoke Li
- Subjects
Physics ,Condensed Matter::Quantum Gases ,Dipole ,Quantum Gases (cond-mat.quant-gas) ,Atomic Physics (physics.atom-ph) ,FOS: Physical sciences ,Molecule ,Atomic physics ,Spin (physics) ,Condensed Matter - Quantum Gases ,Atomic and Molecular Physics, and Optics ,Magnetic field ,Physics - Atomic Physics - Abstract
We have successfully prepared an optically trapped ultracold mixture of $^{23}$Na and $^{87}$Rb atoms and studied their interspecies Feshbach resonances. Using two different spin combinations, several s-wave and p-wave resonances are identified by observing a high inelastic loss and a temperature rising for both species near resonant magnetic field values. The two s-wave resonances observed below 500 G between atoms in the lowest energy level are possible candidates for Feshbach molecule association. Our results are well characterized by a coupled-channel model and are used refining the ground state interaction potentials between $^{23}$Na and $^{87}$Rb. This work opens up the prospect for preparing ultracold ensembles of ground-state bosonic NaRb molecules which are chemically stable and can provide strong dipolar interactions., With major modifications, published in Phys. Rev A(R),87, 050702(2013)
- Published
- 2013
150. Crystal-Phase Control of Catalytically Grown Colloidal CdTe Quantum Wires: Dual Role of n-Tetradecylphosphonic Acid.
- Author
-
Fudong Wang and Buhro, William E.
- Subjects
- *
NANOWIRES , *TELLURIDES , *CADMIUM compounds - Abstract
n-Tetradecylphosphonic acid (TDPA) is an acid and also a source for a strong-binding ligand, n-tetradecylphosphonate (TDPT), for the preparation of the cadmium precursor Cd(DOPT)x(TDPT)1-0.5x (where DOPT = di-n-octylphosphinate). The reaction chemistry of the cadmium precursor and tri-n-octylphosphine telluride (TOPTe) is manipulated to favor the formation of a CdTe solute if the catalytic role of TDPA as an acid is predominant; otherwise the stabilization of the cadmium precursor by TDPT incorporation results in a significant excess of Te in the reaction mixture. These exert opposite consequences on the crystal-phase purity of colloidal CdTe quantum wires (QWs) grown from initial bismuth (Bi) nanoparticles. Primary dissolution of the available CdTe or Te into Bi nanoparticles affords liquid (y ≈ z) or solid (y ≪ z) BixCdyTez catalysts, respectively. The solid catalysts enable the solution-solid-solid growth of nearly phase-pure wurtzite QWs, whereas the liquid catalysts fulfill the solution-liquid-solid growth of polytypic QWs, having wurtzite and zinc blende alternations. This work reveals the dual role of TDPA and rationalizes its use in the crystal-phase controlled synthesis of catalytically grown colloidal QWs. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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