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1.
Summary Bidentate bridging base polymer complexes of acetylacetonatoiron(II) [Fe(acac)2L]n, where L=pyrazine(pyz), 4,4-bipyridine(bpy),trans-1,2-bis(4-pyridyl)ethylene(bpe), 1,2-bis(4-pyridyl)ethane(bpa) and 4,4-trimethylene bipyridine(tmbpy), have been prepared, characterized and oxidized by iodine to give a range of iron(III) and iron(II) complexes [Fe(acac)2L · Ix]n] in which the FeIII/FeII ratios were established by Mössbauer spectroscopy. The electric conductivities of compressed pellets of the polysalts were obtained. The conductivities and Mössbauer parameters (I.S. and Q.S.) both change with respect to the kind of bidentate bridging bases.The conjugation of bridged ligand markedly affects the conductivity of the complexes. 相似文献
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3.
Kai-Ming Chi Hung-Chang Houa Kuo-Hsien Chen Shin-Guang Shyu Yuh-Sheng Wen 《中国化学会会志》1995,42(3):547-554
Copper(I) complexes of general formula (β-diketonate)Cu(7-AcO-NBD), where 7-AcO-NBD = 7-norbornadienyl acetate and β-diketonate = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate (1), 1,1,1-trifluoro-2,4-pentanedionate (2), 2,4-pentanedionate (3), 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate (4), 4,4,4-trifluoro-1-phenyl-1,3-butanedionate (5), were prepared from reactions of CuCl with Na(β-diketonate) in the presence of 7-AcO-NBD. AH compounds were characterized by elemental analyses, 1H, 13C, 19F NMR and IR spectra. Single-crystal strucutre of compound 1 was determined by X-ray diffraction analysis that showed a mononuclear copper species with coordination of a chelating β-diketonate ligand through two oxygen atoms and the 7-AcO-NBD through its C? C double bond and an oxygen atom in the solid state. For compound 1, the crystal data are: triclinic, space group $ {\rm P}\bar 1 $, a= 5.4519(14) Å, b= 11.852(3) Å, c= 13.304(3) Å, α = 74.721(20)° β = 80.220(20)°, γ= 76.848(19)°, Z = 2, RF = 0.060 and Rw = 0.064. Hot-wall chemical vapor deposition experiments revealed that compound 1 is suitable as a precursor for deposition of copper films in the temperature range 170–260 °C. 相似文献
4.
Methods for synthesizing bistolane liquid crystal materials with lateral methyl and ethyl substituents are presented. Some of the bistolanes are nematic at room temperature. These highly conjugated mesogens exhibit wide nematic ranges, small enthalpies of fusion, high birefringence and modest viscosity. Their potential applications for flat panel displays employing light scattering or Bragg reflection and for infrared optically phased arrays are foreseeable. 相似文献
5.
Kuo-Kai Shyu Yu-Te Wu Tzong-Rong Chen Hui-Yun Chen Hui-Hsin Hu Wan-Yuo Guo 《Nonlinear dynamics》2010,61(3):363-372
The fetal cortical complexity is a significant quantification for assessing the development of fetal brain. This study attempts
to quantify the development of fetal cortical complexity using the concept of fractal dimension (FD) analysis. Thirty-two
fetal MR images were selected from Taipei Veterans General Hospital at 27–37 weeks of gestational age (GA). To investigate
the FD of fetal cortical complexity, the entropy based information fractal dimension method (FD
EBI), which is modified from Box-Counting method, was adopted and extended from 2D to 3D. The FD results from overall whole fetal
brains show that the increase of cortical complexity is highly correlated with the gestational age of the fetus. Moreover,
the FD values of right hemispheric brain are larger than those of left hemispheric brain, show that the development of right
hemispheric fetal cortical complexity earlier than the left. These results are in good agreement with normal fetal brain development
and suggest that the FD is an effective means for the quantification of fetal cortical complexity. 相似文献
6.
Left ventricular 4D echocardiogram motion and shape analysis 总被引:1,自引:0,他引:1
The article describes the methodology and the processes of modeling the function and the motion of left ventricle using transesophageal echocardiograph. The parameters can be used in studying the functionality of left ventricle, the status of abnormality of myocardial, and the geometric and morphological of left ventricle in shape analysis. The parameters describes the motion of left ventricle are the left ventricular (LV) floating long axis, the morphological parameters. The LV morphological parameters describe the wall motion, the LV chamber cavity variation, the effective R-ratio of endomyocardial chamber of LV, the area surface curvature, and the global surface curvature circularity. The parameters such as stroke volume, ejection fraction used in evaluation of LV functions are also extracted. 相似文献
7.
This study aims to investigate the complexity of the developing fetal cortical surface based on the notion of fractal dimension
(FD). Forty-four fetal MR images were selected at 22–36 weeks of gestational age (GA) and distributed between two groups:
32 normal fetal brains (excluding twins) and 12 abnormal fetal brains, including twins, mild ventricular dilatation, Cornelia
de Lange syndrome (small brain), and cortical dysplasia (developmental delay). We adopted the commonly used box-counting (BC)
method to estimate the FD of the developing fetal cortical surface. Results from normal fetal brains show that the increase
of cortical complexity is highly correlated with fetal developing weeks of GA. In addition, after 28 weeks of GA, the value
of FD increases more rapidly because of the faster development of convolved folds. In comparison with results from the normal
fetal group, the abnormal fetal brains were examined and the results show that: (1) mild ventricular dilatation has no significant
developing difference compared with normal fetal brains; (2) twins had lower FD than that of normal fetal brains, which may
be a delay of 2–3 weeks; (3) the case of cortical dysplasia also had low FD, indicating that developing delay may mean less
cortical complexity. The results of the normal group are in good agreement with fetal brain development and demonstrate the
effectiveness of FD as a promising means for the quantification of complexity of the fetal cortical surface. 相似文献
8.
King‐Fu Lin Jing‐Yau Shyu 《Journal of polymer science. Part A, Polymer chemistry》2001,39(18):3085-3092
The early cure behavior of 4,4‐dicyanato 1,1‐diphenolethane resin with and without incorporating Cr(acac)3, Co(acac)3, and Cu(acac)2, respectively, as catalysts was investigated by gel permeation chromatography. The curing intermediates were separated by the column elution method and characterized by Fourier transform infrared, 1H, and 3C NMR spectroscopies. The results indicated that the formed dimer in the early cure stage is a straight chain containing a primary amino group. The formed triazine ring in the trimer has a strong catalytic effect on the remaining cyanate groups so that the reactivity of the trimers was significantly increased. The reactivities of the curing intermediates decreased with molecular size until 7‐mer was reached. The initial monomer consumption is described by second‐order‐rate kinetics. In the presence of metal acetylacetonates, the curing reactions may be accelerated, but they did not change the reaction path and preceding sequence of reactivities. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3085–3092, 2001 相似文献
9.
Nonstationary excitations of slender, elastic, cantilevered beams with equal principal moments of inertia are considered. The excitation frequency is slowly increased or decreased through a resonance of the first mode at a constant rate. Three resonances are investigated: primary resonance, superharmonic resonance of order two and subharmonic resonance of order two. After application of Galerkin's method with three modes, the nonlinear, nonstationary response of the first mode of the beam is determined by two methods: integration of the modulation equations obtained from the method of multiple scales, and direct numerical integration of the temporal equations of motion. Time histories are presented and the effects of excitation amplitude, rate of acceleration or deceleration through resonance, damping and initial conditions of the disturbance on the maximum response are studied. The effect of a persistent random disturbance is also examined. Although the excitation acts in the vertical plane, whirling occurs if the beam is subjected to out-of-plane disturbances. 相似文献
10.
When the polarization direction of the laser beam ê lies on the graphene plane, the absorption spectrum A(ω)is isotropic and includes one sharp peak and some shoulders. As for ê along the stacking direction, A(ω) is much weaker, and shows only one broadened peak. Because of the dipole matrix element M(cv), the optical excitations do not fully reflect the features of electronic structures [or the joint density of states (JDOS)]. M(cv) plays an important role in the relationship between A(ω) and JDOS. It is strongly dependent on ê, showing an anisotropic property. 相似文献