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31.
A synthetic method of isoquinolines from aryl ketone O-acyloxime derivatives and internal alkynes has been developed using [Cp*RhCl(2)](2)-NaOAc as the potential catalyst system. The present transformation is carried out by a redox-neutral sequence of C-H vinylation via ortho-rhodation and C-N bond formation of the putative vinyl rhodium intermediate on the oxime nitrogen, where the N-O bond of oxime derivatives could work as an internal oxidant to maintain the catalytic cycle. 相似文献
32.
Jian Shen Shiyang Liu Rong Cao Xin Fan Junjie Du Huaiwu Zhang Zhifang Lin Siu-Tat Chui John Q. Xiao 《Applied Physics A: Materials Science & Processing》2011,105(4):789-793
We experimentally studied magnetically controllable photonic band gaps (PBGs) in two-dimensional magnetic photonic crystals
consisting of ferrite rods. Besides the conventional PBG that relates to Bragg scattering, two other types of PBG, resulting
from magnetic surface plasmon (MSP) resonance and spin-wave resonance, respectively, are observed. The PBG due to MSP resonance
is particularly interesting because of its analogy to surface plasmon in metal; furthermore, it is shown to be completely
tunable by an external static magnetic field from both an experimental and a theoretical point of view. 相似文献
33.
Pengfei Chui Kangning Sun Chang Sun Xiuqing Yang Ting Shan 《Applied Surface Science》2011,257(15):6787-6791
A nanostructured layer was fabricated by using fast multiple rotation rolling (FMRR) on the surface of 316L stainless steel. The microstructure in the surface was characterized by transmission electron microscopy and X-ray diffraction. The effects of FMRR on the microhardness, surface roughness and corrosion behavior of the stainless steel were investigated by microhardness measurements, surface roughness measurements, potentiodynamic polarization curves and pitting corrosion tests. The surface morphologies of pitting corrosion specimens were characterized by scanning electron microscopy. The results show that FMRR can cause surface nanocrystallization with the grain size ranges from 6 to 24 nm in the top surface layer of the sample. The microhardness of FMRR specimen in the top surface layer remarkably increases from 190 to 530 HV. However, the surface roughness slightly rises after FMRR treatment. The potentiodynamic polarization curves and pitting corrosion tests indicated that the FMRR treated 316L stainless steel with a surface nanocrystallized layer reduced the corrosion resistance in a 3.5% NaCl solution and enhanced the pitting corrosion rate in a FeCl3 solution. Possible reasons leading to the decrease in corrosion resistance were discussed. 相似文献
34.
A comprehensive development of multivariate wavelets along with their duals is presented in this paper. The basic ingredients, such as duality relations, reconstruction and decomposition formulas, and the notion of infinite direct sums, are formulated and established in the general nonorthogonal and multivariate setting. Special emphases include duality criteria and stability conditions. As an application, new results are contributed, particularly in dual wavelets, to the existing literature on low-dimensional wavelets. In addition, the special case when the dilation matrix has determinant 2 is studied in some detail. 相似文献
35.
Summary. The objective of this paper is to introduce a fast algorithm for computing the integral wavelet transform (IWT) on a dense
set of points in the time-scale domain. By applying the duality principle and using a compactly supported spline-wavelet as
the analyzing wavelet, this fast integral wavelet transform (FIWT) is realized by applying only FIR (moving average) operations,
and can be implemented in parallel. Since this computational procedure is based on a local optimal-order spline interpolation
scheme and the FIR filters are exact, the IWT values so obtained are guaranteed to have zero moments up to the order of the
cardinal spline functions. The semi-orthogonal (s.o.) spline-wavelets used here cannot be replaced by any other biorthogonal
wavelet (spline or otherwise) which is not s.o., since the duality principle must be applied to some subspace of the multiresolution
analysis under consideration. In contrast with the existing procedures based on direct numerical integration or an FFT-based
multi-voice per octave scheme, the computational complexity of our FIWT algorithm does not increase with the increasing number
of values of the scale parameter.
Received March 3, 1994 相似文献
36.
Li Li Wai-Yeung Wong Chung-Hin Chui Raymond Siu-Ming Wong 《Journal of organometallic chemistry》2011,696(6):1189-8053
A new class of soluble, solution-processable platinum(II) acetylide polymers functionalized with electron-deficient 9,10-anthraquinone spacer and their corresponding diplatinum model complexes were synthesized and characterized. The organometallic polymers exhibit good thermal stability and show low-energy broad absorption bands in the visible region. The effect of the presence of thiophene rings along the polymer chain on the optical and photovoltaic properties of these metallated materials was examined. The low-bandgap polymer with thiophene-anthraquinone-thiophene (donor-acceptor-donor) fragment can serve as a good electron donor for fabricating bulk heterojunction polymer solar cells by blending with a methanofullerene electron acceptor. At the same donor:acceptor blend ratio of 1:4, the light-harvesting ability and solar cell efficiency notably increase when the anthraquinone ring is sandwiched by two thiophene units. Photoexcitation of such polymer solar cells results in a photoinduced electron transfer from the π-conjugated metallopolymer to [6,6]-phenyl C61-butyric acid methyl ester with power conversion efficiency up to ∼ 0.35%. For safety concern, these metallopolymers were also tested for possible cytotoxicity and they do not show significant cytotoxic activity on human liver derived cells and skin keratinocytes at reasonable doses, rendering these functional materials safe to use in practical devices. 相似文献
37.
Dr. Hai‐Feng Xiang Dr. Stephen Sin‐Yin Chui Prof. V. A. L. Roy Prof. Chi‐Ming Che 《化学:亚洲杂志》2011,6(12):3223-3229
Organic photovoltaic (OPV) cells using metal(II) (Pt, Pd, Cu, and Ni) chelates of 8‐hydroxyquinoline (Hq) or 5,7‐dimethyl‐8‐hydroxy‐quinoline (HMe2q) as an electron donor were fabricated by vacuum deposition. The bis(5,7‐dimethyl‐8‐hydroxyquinolinato)platinum(II) [Pt(Me2q)2]‐based OPVs showed the best performance with an open voltage (VOC) of 0.42 V, a short circuit current density (JSC) of 14.8 mA cm?2, and a maximum power conversion efficiency (ηP) of 2.4 %. The X‐ray single‐crystal structures together with the grazing incidence X‐ray diffraction (GIXRD) data of thin film samples reveal that the peripheral methyl substituent(s) and platinum(II) ion are essential for the high degree of film crystallinity resulting in improved performance of the as‐fabricated field‐effect transistors (FETs) and OPV cells. 相似文献
38.
Dr. Jia Wang Dr. Yong Chen Dr. Yuen‐Chi Law Meiyi Li Dr. Ming‐Xin Zhu Dr. Wei Lu Dr. Stephen Sin‐Yin Chui Dr. Nianyong Zhu Prof. Dr. Chi‐Ming Che 《化学:亚洲杂志》2011,6(11):3011-3019
A series of phosphorescent terpyridyl platinum(II) complexes with ancillary biphenylacetylide ligands, namely, [(R3tpy)PtC≡C(biphenyl)]X (R=tBu, H, or Et2N; tpy=2,2′;6′,2′′‐terpyridyl; X is an anion) were synthesized and structurally characterized by various spectroscopic techniques and X‐ray diffraction methods. Despite a lack of long alkyl chain(s) or hydrogen‐bonding motif(s), complexes [(tpy)PtC≡C(biphenyl)]Cl and [(tBu3tpy)PtC≡C(biphenyl)]X (X=Cl, ClO4, PF6, or BF4) were found to gelate water and organic solvents, respectively. The self‐aggregation of these complexes in solutions and the resulting gels were investigated with variable‐temperature (VT) 1H NMR spectroscopy, polarized optical microscopy, and absorption/emission spectroscopy. SEM micrographs on dry gels revealed entangled nanofibers with diameters of 20–40 nm and lengths of tens of micrometers. Powder X‐ray diffraction (PXRD) study revealed various degrees of crystallinity of these fibrillar nanostructures. The substituents on both the terpyridyl and acetylide ligands and counterion of these complexes play a profound but concerted role in tuning the intermolecular metal???metal and/or π–π interactions, and hence the gelation properties. 相似文献
39.
40.
The objective of this paper is to introduce a general scheme for the construction of interpolatory approximation formulas and compactly supported wavelets by using spline functions with arbitrary (nonuniform) knots. Both construction procedures are based on certain ``optimally local' interpolatory fundamental spline functions which are not required to possess any approximation property.