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941.
Van Thuan Le Thi Kieu Ngan Tran Dai Lam Tran Hoang Sinh Le Van Dat Doan Quang Dung Bui 《Journal of Dispersion Science and Technology》2013,34(12):1761-1776
AbstractIn the present work, a novel composite consisting of magnetite, activated carbon from spent coffee grounds and natural clay (MACCC) was prepared by a one-pot synthesis method via a simultaneous activation and magnetization processes. Various techniques (XRD, FTIR, SEM, TEM, EDX, BET) were utilized to characterize the synthesized composite before utilizing it as an adsorbent for removal of Cu(II), Ni(II) and Pb(II) ions from aqueous solutions. Conditions for removal of heavy metals were thoroughly optimized as 25?°C, pH of 5.5, adsorbent dosage of 2?g L?1, and a contact time of 60?min. Three models of pseudo first-, second-order and intraparticle diffusion as well as three models of Langmuir, Freundlich, and Temkin were used to analyze kinetics and isotherms of the adsorption process. Thermodynamics was discussed completely. Regeneration and recyclability of the adsorbent were also evaluated. Based on the analysis of experimental results, a possible adsorption mechanism of heavy metals onto the synthesized composite was proposed. The maximum capacities caculated from Langmuir model followed the order of Pb(II) > Cu(II) > Ni(II) as 143.56, 96.16 and 84.86?mg·g?1, respectively. The overall results indicated that MACCC is a potential adsorbent for removal of toxic Pb(II), Cu(II) and Ni(II) ions from wastewater due to simple preparation, high removal efficiency and good recyclability. 相似文献
942.
Experiments in the past two decades have shown that the glass transition temperature of polymer films can become noticeably different from that of the bulk when the film thickness is decreased below ca. 100 nm. It is broadly believed that these observations are caused by a nanometer interfacial layer with dynamics faster or slower than that of the bulk. In this paper, we examine how this idea may be realized by using a two-layer model assuming a hydrodynamic coupling between the interfacial layer and the remaining, bulk-like layer in the film. Illustrative examples will be given showing how the two-layer model is applied to the viscosity measurements of polystyrene and polymethylmethacrylate films supported by silicon oxide, where divergent thickness dependences are observed. 相似文献
943.
Alan Kwun‐Wa Chan Elizabeth Suk‐Hang Lam Dr. Anthony Yiu‐Yan Tam Daniel Ping‐Kuen Tsang Dr. Wai Han Lam Dr. Mei‐Yee Chan Prof. Dr. Wing‐Tak Wong Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13910-13924
A series of luminescent cyclometalated platinum(II) complexes of N^C^N ligands [N^C^N=2,6‐bis(benzoxazol‐2′‐yl)benzene (bzoxb), 2,6‐bis(benzothiazol‐2′‐yl)benzene (bzthb), and 2,6‐bis(N‐alkylnaphthoimidazol‐2′‐yl)benzene (naphimb)] has been synthesized and characterized. Two of the platinum(II) complexes have been structurally characterized by X‐ray crystallography. Their electrochemical, electronic absorption, and luminescence properties have been investigated. In dichloromethane solution at room temperature, the cyclometalated N^C^N platinum(II) complexes exhibited rich luminescence with well‐resolved vibronic‐structured emission bands. The emission energies of the complexes are found to be closely related to the electronic properties of the N^C^N ligands. By varying the electronic properties of the cyclometalated ligands, a fine‐tuning of the emission energies can be achieved, as supported by computational studies. Multilayer organic light‐emitting devices have been prepared by utilizing two of these platinum(II) complexes as phosphorescent dopants, in which a saturated yellow emission with Commission International de I′Eclairage coordinates of (0.50, 0.49) was achieved. 相似文献
944.
Dr. Yongguang Li Elizabeth Suk‐Hang Lam Dr. Anthony Yiu‐Yan Tam Dr. Keith Man‐Chung Wong Dr. Wai Han Lam Prof. Dr Lixin Wu Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(30):9987-9994
A series of cholesterol‐/estradiol‐appended alkynylplatinum(II) complexes with tridentate N‐donor ligands, based on 2,6‐bis(1‐alkylpyrazol‐3‐yl)pyridine, has been synthesized and characterized by 1H NMR spectroscopy, FAB‐mass spectrometry, and elemental analysis. Their photophysical properties have also been investigated. Computational studies have been performed to provide insights into the nature of the electronic transitions. Some of the complexes have been found to form stable thermo‐ and mechanoresponsive supramolecular gels. 相似文献
945.
The synthesis of P-chirogenic diarylphosphinocarboxylic acids was achieved, from which a new class of amido- and amino-diphosphine ligands (PNP*) were derived, containing an l-proline backbone. The catalytic activities of the novel ligands were evaluated in the palladium-catalysed allylic alkylation reaction of 1,3-diphenylpropenyl acetate. 相似文献
946.
Duong Minh Duc Nguyen Dinh Hoang Lam Hoang Nguyen 《Journal of Mathematical Analysis and Applications》2006,323(1):441-455
We prove a version of Lagrange multipliers theorem for nonsmooth functionals defined on normed spaces. Applying these results, we extend some results about saddle point optimality criteria in mathematical programming. 相似文献
947.
Uyen Tu Thi Doan Duy Khanh Le Truong Lam Huynh Tung Thanh Ngo Trieu Quang Vo Dr. Minh Thu Tran Thi Anh Tuan Thanh Pham Vinh Cao Tran Phuong Tuyet Nguyen Ngoc Kim Pham 《Chemphyschem》2023,24(18):e202300210
In this study, the features of resistive random access memory (RRAM) employing a straightforward Cr/MAPbI3/FTO three-layer structure have been examined and clarified. The device displays various resistance switching (RS) behavior at various sweep voltages between 0.5 and 5 V. The RS effect has a conversion in the direction of the SET and RESET processes during sweeping for a number of cycles at a specific voltage. The directional change of the RS processes corresponds to the dominant transition between the generation/recombination of iodide ion and vacancy in the MAPbI3 perovskite layer and the electrochemical metallization of the Cr electrode under the influence of an electric field, which results in the conductive filament (CF) formation/rupture. At each stage, these processes are controlled by specific charge conduction mechanisms, including Ohmic conduction, space-charge-limited conduction (SCLC), and variable-range hopping (VRH). By identifying the biased voltage and the quantity of voltage sweep cycles, one can take a new approach to control or modulate the pathways for effective charge transport. This new approach is made possible by an understanding of the RS characteristics and the corresponding mechanisms causing the variation of RS behavior in the structure. 相似文献
948.
Zhen Li Qianqian Li Anjun Qin Yongqiang Dong Jacky W. Y. Lam Yuping Dong Cheng Ye Jingui Qin Ben Zhong Tang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(19):5672-5681
A new disubstituted polyacetylene with indolylazo moieties in its side chains ( 9 ) was synthesized by a post functionalization strategy, which was difficult, or perhaps impossible, to obtain from the direct polymerization of its corresponding monomer. The polymer is soluble in common solvents and thermally stable. The polymer shows good optical transparency with an absorption maximum at 393 nm and a band edge at ~530 nm. Its poled film exhibits a resonant d33 value of 17.9 pm/V and its optical nonlinearity is resistant to thermal decay at up to 147 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5672–5681, 2006 相似文献
949.
950.
The focus of this study is the application of a non-parametric model called operational competitiveness rating analysis (OCRA), to obtain ratings that gauge the relative operational performance of the application software development teams of a large bank in Hong Kong. The computed ratings would be the basis of important management decisions relating to the connection between personnel performance and benefits. This application of OCRA requires the values of resources consumed and outputs generated. Cost figures were used to measure the teams' resource consumption. The value of the teams' software output was measured by function point analysis. The performance ratings obtained by OCRA are compared with data envelopment analysis (DEA) ratings and ratio scores. Comments are offered on the implementation of the proposed approach. 相似文献