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排序方式: 共有537条查询结果,搜索用时 15 毫秒
31.
Kyung Ju Lee Muhammad Salman Maqbool Pullur Anil Kumar Kwang Ho Song Heon Phil Ha 《Research on Chemical Intermediates》2013,39(7):3265-3277
Economic production of titanium dioxide (yield >98 %) from ilmenite has been achieved by use of a modified sulfate reduction process. A series of samples were prepared by varying the concentration of titanium dioxide nuclei (0.2, 0.3, and 0.6 %) and further impregnation with antimony and vanadia. The structural and acidic properties of the samples were comprehensively studied by X-ray diffraction (XRD), transmission electron microscopy, BJH pore size distribution, and temperature-programmed desorption of NH3. The XRD results revealed the presence of intense peaks from anatase titanium dioxide. Enhancement of surface area was observed for second-time filtered samples, possibly because of loss of iron from the bulk. As a result, formation of additional micropores was apparent from N2 adsorption and desorption isotherms. Among all the antimony and vanadia-doped samples, the first-time filtered sample with the low concentration of nuclei (0.2 %) had the highest catalytic activity at low temperatures, owing to its larger pore size and abundant acidic species. 相似文献
32.
Khatoon Rabia Uddin Riaz Khurshid Salman Anwar Faiza Iqbal Saba Baloch Parwaiz Ahmed Khan Attaullah 《Journal of Analytical Chemistry》2022,77(5):611-617
Journal of Analytical Chemistry - A reliable, easy, and reproducible method was developed for the quantification of λ-cyhalothrin and malathion residues in desert locust. For the extraction, a... 相似文献
33.
Salman Z Wang D Chow KH Hossain MD Kreitzman SR Keeler TA Levy CD MacFarlane WA Miller RI Morris GD Parolin TJ Saadaoui H Smadella M Kiefl RF 《Physical review letters》2007,98(16):167001
A low energy radioactive beam of polarized 8Li has been used to observe the vortex lattice near the surface of superconducting NbSe2. The inhomogeneous magnetic-field distribution associated with the vortex lattice was measured using depth-resolved beta-detected NMR. Below Tc, one observes the characteristic line shape for a triangular vortex lattice which depends on the magnetic penetration depth and vortex core radius. The size of the vortex core varies strongly with the magnetic field. In particular, in a low field of 10.8 mT, the core radius is much larger than the coherence length. The possible origin of these giant vortices is discussed. 相似文献
34.
Here, we present a method to synthesize expandable spherical polystyrene beads containing well-dispersed water microdroplets. The beads, 2–3 mm in diameter, were prepared through surfactant-free Pickering emulsion polymerization in water-in-oil-in-water (w/o/w) system using cross-linked starch nanoparticles (CSTN) as emulsifier. The CSTNs were in situ surface-modified by styrene maleic anhydride copolymer as confirmed by infrared spectroscopy and contact angle analysis. The entrapped water microdroplets with the average size of 3–4 μm were shown to be surrounded by a dense layer of the CSTN. The number droplet density as well as water encapsulation efficiency in the polystyrene beads increased with the CSTN concentration. Furthermore, regardless of CSTN content, all samples exhibited high encapsulation stability of over 68 % after 3 months. These characteristics along with good expansion behavior suggest the synthesized beads as expandable polystyrene containing water as a green blowing agent. 相似文献
35.
Dr. Zhen Jiang Ming Li Tan Mahdiar Taheri Dr. Qiao Yan Prof. Takuya Tsuzuki Dr. Michael G. Gardiner Broden Diggle Prof. Luke A. Connal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(18):7115-7122
The most pressing challenges for light-driven hydrogel actuators include reliance on UV light, slow response, poor mechanical properties, and limited functionalities. Now, a supramolecular design strategy is used to address these issues. Key is the use of a benzylimine-functionalized anthracene group, which red-shifts the absorption into the visible region and also stabilizes the supramolecular network through π–π interactions. Acid–ether hydrogen bonds are incorporated for energy dissipation under mechanical deformation and maintaining hydrophilicity of the network. This double-crosslinked supramolecular hydrogel developed via a simple synthesis exhibits a unique combination of high strength, rapid self-healing, and fast visible-light-driven shape morphing both in the wet and dry state. As all of the interactions are dynamic, the design enables the structures to be recycled and reprogrammed into different 3D objects. 相似文献
36.
An analysis of the semiclassical regime of the quantum-classical transition is given for open, bounded, one-dimensional chaotic dynamical systems. Environmental fluctuations-characteristic of all realistic dynamical systems-suppress the development of a fine structure in classical phase space and damp nonlocal contributions to the semiclassical Wigner function, which would otherwise invalidate the approximation. This dual regularization of the singular nature of the semiclassical limit is demonstrated by a numerical investigation of the chaotic Duffing oscillator. 相似文献
37.
Kazem Jeddi Nader Taheri Qazvini Seyed Hassan Jafari Hossein Ali Khonakdar Javad Seyfi Uta Reuter 《Journal of Polymer Science.Polymer Physics》2011,49(4):318-326
Polymer–silicate nanocomposites based on poly (ethylene oxide), PEO, poly(methyl methacrylate), PMMA, and sodium montmorillonite clay were fabricated and characterized to investigate the effect of nanolayered silicates on segmental dynamics of PEO/PMMA blends. X‐ray results indicate the formation of an exfoliated morphology in the nanocomposites. At low silicate contents, an enhancement in segmental dynamics of blend nanocomposites and also PEO, minor component in blend, is observed at temperature region below blend glass transition. This result can be attributed to the improvement of the confinement effect of rigid PMMA matrix on the PEO chains by introducing a low amount of layered silicates. On the other hand, at high silicate contents, an enhancement in segmental dynamics of blend nanocomposites and PEO is observed at temperature region above blend glass transition. This behavior could be interpreted based on the reduction of monomeric friction between two polymer components, which can facilitate segmental motions of blend components in nanocomposite systems. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
38.
Dariush Rostamifard Mehdi Fallahnezhad Salman Zaferanlouei Saeed Setayeshi Mohammad Hassan Moradi 《Heat and Mass Transfer》2011,47(4):439-448
A hybrid high order neural network (HHONN) and a feed forward neural network (FNN) are developed and applied to find an optimized
empirical correlation for prediction of dryout (DO) heat transfer. The values predicted by the HHONN and FNN models are compared
with each other and also with the previous values of empirical correlation. HONN successfully provides an efficient open-box
model of nonlinear input–output mapping which provides easier understanding of data mining. By removing the hidden layers,
HONN structures become simpler than FNNs and initialization of learning parameters (weights) will not be catastrophic. The
RMS results show that the HHONN model has superior fitting specification for prediction of DO heat transfer problem compared
to the other prediction methods. 相似文献
39.
40.
Hossein Mahdavi B. O. Mahdi Sadeghzadeh Nader Taheri Qazvini 《Journal of Polymer Science.Polymer Physics》2009,47(5):455-462
The phase behavior of poly(N‐tertbutylacrylamide‐co‐acrylamide) (PNTBAM) in pure water and mixture of water–methanol is studied at different temperatures. The different compositions of PNTBAM are prepared by free‐radical polymerization technique and their phase behavior is studied by turbidimetry. The effects of copolymer and solvent composition on the phase behavior of the copolymers are discussed. It has been suggested that the inhomogenities in polymer chains are responsible for lowering the rate of phase transition by increasing the N‐tertbutylacrylamide (NTBAM) and methanol contents in copolymer and mixture, respectively. For the first time we have revealed that there are second‐order binary interactions in the water–methanol which are dominant in the special range of copolymer composition. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 455–462, 2009 相似文献