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Jiang DX, Zheng XH, Xu HH, Wong NB. X-ray diffraction, DFT, spectroscopic study and insecticidal activity of (3-cyano-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((trifluoromethyl)sulfinyl)-1H-pyrazol-5-yl)(2-(triethylammonio)acetyl)amide inner salt. CRYSTALLOGR REP+ 2014. [DOI: 10.1134/s1063774514080045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Tang QY, Shafiq I, Chanl YC, Wong NB, Cheung R. Study of the dispersion and electrical properties of carbon nanotubes treated by surfactants in dimethylacetamide. J Nanosci Nanotechnol 2010; 10:4967-4974. [PMID: 21125836 DOI: 10.1166/jnn.2010.2224] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this study, the effects of sodium dodecyl benzene sulfonate, polyvinylpyrrolidone, sodium dodecyl benzene sulfonate/polyvinylpyrrolidone, and Triton X-100 on the dispersion of 0.1 wt% carbon nanotubes in dimethylacetamide are reported. Sedimentation results show that except for sodium dodecyl benzene sulfonate, all the surfactant-assisted carbon nanotube solutions have visually-stable dispersions for at least two months, and even the samples without a surfactant gave no obvious deposition. UV-Vis spectra of the dispersions with and without acid-treatment proved that the carboxyl group attached to the carbon nanotubes positively improves the dispersion effect. The states of aggregation of carbon nanotubes treated by different surfactants are distinctive, and the electrical properties of carbon nanotubes are strongly related to these states of aggregation. The best dispersing and stabilizing effect was found in the sodium dodecyl benzene sulfonate/polyvinylpyrrolidone sample, which also gave the lowest resistance (2.15 x 10(4) omega at 20 V) among all the surfactant-treated stable suspensions.
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Affiliation(s)
- Q Y Tang
- Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
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Shi L, Tin KC, Wong NB, Wu XZ, Li CL. KINETICS AND MECBANISM OF BENZOTHIOPHENE HYDRODESULFURIZATION OVER NiO-MoO/y-Al203 COMMERCIAL CATALYST. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/08843759608947611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- L. Shi
- a Department of biology and chemistry , City university of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - K. C. Tin
- a Department of biology and chemistry , City university of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - N. B. Wong
- a Department of biology and chemistry , City university of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - X. Z. Wu
- a Department of biology and chemistry , City university of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - C. L. Li
- a Department of biology and chemistry , City university of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong
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Sun XH, Lam S, Sham TK, Heigl F, Jürgensen A, Wong NB. Synthesis and Synchrotron Light-Induced Luminescence of ZnO Nanostructures: Nanowires, Nanoneedles, Nanoflowers, and Tubular Whiskers. J Phys Chem B 2005; 109:3120-5. [PMID: 16851331 DOI: 10.1021/jp044926v] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ZnO nanostructures, including single-crystal nanowires, nanoneedles, nanoflowers, and tubular whiskers, have been fabricated at a modestly low temperature of 550 degrees C via the oxidation of metallic Zn powder without a metal catalyst. Specific ZnO nanostructures can be obtained at a specific temperature zone in the furnace depending on the temperature and the pressure of oxygen. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) studies show that ZnO nanostructures thus prepared are single crystals with a wurtzite structure. X-ray excited optical luminescence (XEOL) from the ZnO nanostructures show noticeable morphology-dependent luminescence. Specifically, ZnO nanowires of around 15 nm in diameter emit the strongest green light. The morphology of these nanostructures, their XEOL, and the implication of the results will be discussed.
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Affiliation(s)
- X H Sun
- Department of Chemistry, University of Western Ontario, London, Canada N6A 5B7
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Teo BK, Li CP, Sun XH, Wong NB, Lee ST. Silicon−Silica Nanowires, Nanotubes, and Biaxial Nanowires: Inside, Outside, and Side-by-Side Growth of Silicon versus Silica on Zeolite. Inorg Chem 2003; 42:6723-8. [PMID: 14552624 DOI: 10.1021/ic034397u] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It was demonstrated that zeolite can be used as a pseudo-template to grow very fine and uniform silicon nanostructures via disproportionation reaction of SiO by thermal evaporation. Three distinct types of composite nanowires and nanotubes of silicon and silica were grown on the surfaces of zeolite Y pellets. The first type is formed by an ultrafine crystalline silicon nanowire sheathed by an amorphous silica tube (a silicon nanowire inside a silica nanotube). The second type is formed by a crystalline silicon nanotube filled with amorphous silica (a silicon nanotube outside a silica nanowire). The third type is a biaxial silicon-silica nanowire structure with side-by-side growth of crystalline silicon and amorphous silica. These silicon nanostructures exhibit unusually intense photoluminescence (in comparison to ordinary silicon nanowires).
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Affiliation(s)
- Boon K Teo
- Department of Chemistry, University of Illinois at Chicago, 845 W Taylor Street, Chicago, Illinois 60607,
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Sun XH, Wang SD, Wong NB, Ma DDD, Lee ST, Teo BK. FTIR spectroscopic studies of the stabilities and reactivities of hydrogen-terminated surfaces of silicon nanowires. Inorg Chem 2003; 42:2398-404. [PMID: 12665376 DOI: 10.1021/ic020723e] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Attenuated total reflection Fourier transform infrared (FTIR) spectroscopy was used to characterize the surface species on oxide-free silicon nanowires (SiNWs) after etching with aqueous HF solution. The HF-etched SiNW surfaces were found to be hydrogen-terminated; in particular, three types of silicon hydride species, the monohydride (SiH), the dihydride (SiH(2)), and the trihydride (SiH(3)), had been observed. The thermal stability of the hydrogen-passivated surfaces of SiNWs was investigated by measuring the FTIR spectra after annealing at different elevated temperatures. It was found that hydrogen desorption of the trihydrides occurred at approximately 550 K, and that of the dihydrides occurred at approximately 650 K. At or above 750 K, all silicon hydride species began to desorb from the surfaces of the SiNWs. At around 850 K, the SiNW surfaces were free of silicon hydride species. The stabilities and reactivities of HF-etched SiNWs in air and water were also studied. The hydrogen-passivated surfaces of SiNWs showed good stability in air (under ambient conditions) but relatively poor stability in water. The stabilities and reactivities of the SiNWs are also compared with those of silicon wafers.
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Affiliation(s)
- X H Sun
- Center of Super-Diamond & Advanced Film (COSDAF), Department of Biology and Chemistry, City University of Hong Kong, Hong Kong SAR, China
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Affiliation(s)
- W. C. Lu
- COSDAF, City University of Hong Kong, Kowloon, Hong Kong S.A.R., P. R. China, Institute of Theoretical Chemistry & State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, P. R. China, and Institute of Functional Material Chemistry, Northeast Normal University, Changchun 130024, P. R. China
| | - R. Q. Zhang
- COSDAF, City University of Hong Kong, Kowloon, Hong Kong S.A.R., P. R. China, Institute of Theoretical Chemistry & State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, P. R. China, and Institute of Functional Material Chemistry, Northeast Normal University, Changchun 130024, P. R. China
| | - Q. J. Zang
- COSDAF, City University of Hong Kong, Kowloon, Hong Kong S.A.R., P. R. China, Institute of Theoretical Chemistry & State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, P. R. China, and Institute of Functional Material Chemistry, Northeast Normal University, Changchun 130024, P. R. China
| | - N. B. Wong
- COSDAF, City University of Hong Kong, Kowloon, Hong Kong S.A.R., P. R. China, Institute of Theoretical Chemistry & State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, P. R. China, and Institute of Functional Material Chemistry, Northeast Normal University, Changchun 130024, P. R. China
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Abstract
The reductive growth of metal clusters on silicon nanowires (SiNWs) is reported. The HF-etched SiNWs were found to reduce ligated Au-Ag clusters of single size, shape, composition, and structure. In the process, the surfaces of the SiNWs were reoxidized. The reductive cluster growth on the SiNW surface was followed by high-resolution transmission electron microscopy (HRTEM). The reduced metal clusters grew to different sizes in the nanometer regime (1-7 nm in diameter) on the SiNW surfaces. At sizes greater than approximately 7 nm, they tend to separate from the SiNW surfaces. Further growth and/or agglomeration of these colloidal particles to sizes greater than roughly 25 nm in diameter eventually causes the particles to precipitate from solution. Two interesting phenomena, the "sinking cluster" and the "cluster fusion" processes, were observed under TEM.
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Affiliation(s)
- X H Sun
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
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Affiliation(s)
- C. P. Li
- Center of Super-Diamond and Advanced Films (COSDAF), The City University of Hong Kong, Hong Kong SAR, China, Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong SAR, China, Department of Biology and Chemistry, The City University of Hong Kong, Hong Kong SAR, China, and Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
| | - X. H. Sun
- Center of Super-Diamond and Advanced Films (COSDAF), The City University of Hong Kong, Hong Kong SAR, China, Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong SAR, China, Department of Biology and Chemistry, The City University of Hong Kong, Hong Kong SAR, China, and Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
| | - N. B. Wong
- Center of Super-Diamond and Advanced Films (COSDAF), The City University of Hong Kong, Hong Kong SAR, China, Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong SAR, China, Department of Biology and Chemistry, The City University of Hong Kong, Hong Kong SAR, China, and Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
| | - C. S. Lee
- Center of Super-Diamond and Advanced Films (COSDAF), The City University of Hong Kong, Hong Kong SAR, China, Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong SAR, China, Department of Biology and Chemistry, The City University of Hong Kong, Hong Kong SAR, China, and Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
| | - S. T. Lee
- Center of Super-Diamond and Advanced Films (COSDAF), The City University of Hong Kong, Hong Kong SAR, China, Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong SAR, China, Department of Biology and Chemistry, The City University of Hong Kong, Hong Kong SAR, China, and Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
| | - Boon K. Teo
- Center of Super-Diamond and Advanced Films (COSDAF), The City University of Hong Kong, Hong Kong SAR, China, Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong SAR, China, Department of Biology and Chemistry, The City University of Hong Kong, Hong Kong SAR, China, and Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
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Affiliation(s)
- J. Q. Hu
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
| | - X. L. Ma
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
| | - N. G. Shang
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
| | - Z. Y. Xie
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
| | - N. B. Wong
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
| | - C. S. Lee
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
| | - S. T. Lee
- Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, SAR, P. R. China
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Mi BX, Gao ZQ, Liu MW, Chan KY, Kwong HL, Wong NB, Lee CS, Hung LS, Lee ST. New polycyclic aromatic hydrocarbon dopants for red organic electroluminescent devices. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b110153f] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wong TC, Wong NB, Tanner PA. A Fourier Transform IR Study of the Phase Transitions and Molecular Order in the Hexadecyltrimethylammonium Sulfate/Water System. J Colloid Interface Sci 1997; 186:325-31. [PMID: 9056361 DOI: 10.1006/jcis.1996.4674] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Variable temperature Fourier transform infrared (FTIR) spectroscopy was used to study the transition between the micellar and the coagel phases, and between the cubic and the coagel phases, for the hexadecyltrimethylammonium sulfate (CTAS)/water system. The phase transition takes place at 15°C for the coagel to micelle transition and 17°C for the coagel to cubic phase transition. CTAS in the solid state at two temperatures was also studied by FTIR to provide comparison with the aqueous samples on the molecular motion and packing in these phases. The present FTIR data also suggest the formation of rod-like micelles upon the addition of electrolyte, NaCl, to the CTAS/water system.
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Affiliation(s)
- TC Wong
- Department of Chemistry, University of Missouri, Columbia, Missouri, 62511
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Abstract
The rheological properties of dental waxes control their fabrication procedures and are dominated by their temperature dependence. Indeed, it is their rapid change in deformability with temperature which enables them to be used. Some measure of flow rate is therefore needed for characterization and quality control. A modified Stokes' method is proposed which allows measurement of an analogue of Newtonian viscosity and is suited to routine use in the range 10(4)-10(10) Pa.s, and which leads naturally to a determination of the activation energy for the process. This activation energy is of the order of 700 kJ/mole at low stress.
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