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171.
利用配体 5-(二甲基氨基)间苯二甲酸(H2dia)和咪唑(mdz)分别与锌(Ⅱ)和铜(Ⅱ)金属盐反应,制备了 3 例过渡金属配合物[Zn(dia)(mdz)2]·2H2O (1)、[Cu(dia)(mdz)2(DMF)] (2)和[Cu(dia)(mdz)2]·H2O (3)。利用单晶 X射线衍射、元素分析、红外光谱、热重和Hirshfeld表面分析对其进行了结构表征。结果表明配合物1和2为一维线状链,1中每个四配位的Zn(Ⅱ)处于变形四面体中心,2中Cu(Ⅱ)中心拥有五配位的三角双锥几何构型。改变合成溶剂条件得到锯齿形一维链状配合物3,其四配位Cu(Ⅱ)中心展现出对称平面四边形构型。上述结果说明,金属离子几何构型以及合成溶剂可能对配合物结构具有重要影响。丰富的分子间氢键帮助3例配合物形成稳定的三维超分子结构。热重分析表明,3例配合物均具有良好的热稳定性。固体荧光分析表明配合物1具有较强荧光性,而配合物2和3荧光强度均远低于配体。 相似文献
172.
The phase diagrams of ferroelectric thin films with two surface layers described by the transverse Ising model have been studied under the mean-field approximation. We discuss the effects of the exchange interaction and transverse field parameters on the phase diagrams. The results indicate that the phase transition properties of the phase diagrams can be greatly modified by changing the transverse Ising model parameters. In addition, the crossover features of the parameters from the ferroelectric dominant phase diagram to the paraelectric dominant phase diagram are determined for ferroelectric thin films with two surface layers. 相似文献
173.
174.
Jason Miller 《Communications in Mathematical Physics》2011,308(3):591-639
We study the massless field on \({D_n = D \cap \tfrac{1}{n} \mathbf{Z}^2}\), where \({D \subseteq \mathbf{R}^2}\) is a bounded domain with smooth boundary, with Hamiltonian \({\mathcal {H}(h) = \sum_{x \sim y} \mathcal {V}(h(x) - h(y))}\). The interaction \({\mathcal {V}}\) is assumed to be symmetric and uniformly convex. This is a general model for a (2 + 1)-dimensional effective interface where h represents the height. We take our boundary conditions to be a continuous perturbation of a macroscopic tilt: h(x) = n x · u + f(x) for \({x \in \partial D_n,\,u \in \mathbf{R}^2}\), and f : R 2 → R continuous. We prove that the fluctuations of linear functionals of h(x) about the tilt converge in the limit to a Gaussian free field on D, the standard Gaussian with respect to the weighted Dirichlet inner product \({(f,g)_\nabla^\beta = \int_D \sum_i \beta_i \partial_i f_i \partial_i g_i}\) for some explicit β = β(u). In a subsequent article, we will employ the tools developed here to resolve a conjecture of Sheffield that the zero contour lines of h are asymptotically described by SLE(4), a conformally invariant random curve. 相似文献
175.
Shi-Kuo Li Chuan-Hao Li Fang-Zhi Huang Yang Wang Yu-Hua Shen An-Jian Xie Qiong Wu 《Journal of nanoparticle research》2011,13(7):2865-2874
Uniform Cu2O hollow spheres fabricated by single-crystalline particles (smaller than 20 nm) are facile synthesized in ethylene glycol
(EG) solution by a simple solvothermal route without using pre-fabricated templates and reductive agents. EG in this protocol
is not only used as a solvent, complexing agent, and reducing agent, but also served as a structure-directing agent for the
formation of hollow structure. By control of reaction conditions, such as reaction time, temperature, and the anions, the
morphology and structure of the hollow spheres can be tuned. A coordination adsorption and oriented attachment and Ostwald
ripening mechanism is proposed for explaining the formation process of hollow Cu2O spheres in EG solution; and importantly, the hollow Cu2O spheres exhibit an excellent property for the electro-catalytic oxidization of ascorbic acid in acetic acid buffer solution.
Moreover, the hollow spherical Cu2O particles could be potentially applied in catalysis, sensor, and as model for fundamental research. 相似文献
176.
We derive symplectically invariant uncertainty relations for a set of canonically conjugated variables. The uncertainty relations obtained are multimode analogs of the Robertson–Schrödinger inequalities. Our uncertainty relations are equivalent to the necessary and sufficient conditions for a matrix to be a correlation matrix of some quantum state, obtained by R. Simon and coauthors. The advantage of our inequalities, compared to that suggested by Simon, consists in its simplicity and more obvious symplectic invariance. We derive our inequalities for the case of a two-mode system in explicit form. Particular cases of small and large degrees of correlation between the first and second modes are analyzed in detail. 相似文献
177.
The physical behavior of a fluid in contact with solid layers is still not fully understood. The present work focuses on the
study and understanding of thermodynamic and structural properties of gold–water nanolayer mixtures using molecular dynamics
simulations. Two different systems are considered, where approximately 1,700 water molecules are confined between gold nanolayers
with separations of 7.4 and 6.2 nm, respectively. Novelties of the present work are in the use of accurate force fields for
modeling the inter- and intra-molecular interactions of the components, and providing comprehensive thermodynamic properties
of the mixtures. The results are validated by examination of the pure fluid and pure solid properties. Results indicate that
the thermodynamics of the system does not behave as an ideal mixture. The structure of the pure fluid is also analyzed and
compared against the structure of the confined fluid in the mixture. Anisotropicity is observed in the fluid structure close
to the surface of the nanolayer. Higher ordering and higher flux are detected in the fluid molecules close to the fluid–solid
interface. Unusual thermodynamic behavior, anisotropicity, liquid layering, and higher interfacial fluid flux could be just
some of the factors leading to the enhanced energy transport observed in mixtures involving at least one nanoscale component,
such as nanofluids. 相似文献
178.
The Er3+ -Yb3+ codoped in Li2O content tungsten -tellurite (TWL) transparent glasses are synthesized and measured the absorption, Raman and upconversion
luminescence (UPL) spectra. At room temperature intense green emission peak at 560 nm ( 4S3/2→4I15/2) and red emission peak at 670 nm ( 4F9/2→4I15/2) of Er3+ observed even at minimum 86 mW pumping power of infrared 980 nm excitation. For structure of the TWL glass, Raman spectrum
result revealed that an important role of WO3 in the formation of glass network linkage with Li2O. Under this influence estimated lifetime of the 4I11/2 of Er3+ was 1.89 μs and due to lower phonon energy of the glass produce strong upconversion signal. The effect of Er2O3 concentration on emission intensity result indicated that green emission intensity initially increase in compare to red emission.
Under the 980 nm pump power variation measured the relatively increases the red emission to the green emission intensity and
analyze the possible upconversion mechanism and process. 相似文献
179.
Ethynylated phenothiazine based fluorescent boronic acid probes were prepared. Sonogashira coupling reaction was used to introduce
substituted phenylethynylene fragments to the phenothiazine fluorophore to extend the π-conjugation and to enhance the emission
property. The photophysical properties and the binding properties of these probes with hydroxyl acids were investigated. We
found that the probes with significant ICT effect show emissions which are sensitive to solvent polarity. The phenothiazine
moiety is proved to be electron-donating. We found the substitution profile imparts significant effect on the photophysical
properties of the probes. For example, one of the probes shows d-PeT effect, whereas the regioisomer probe with similar π-conjugation
fragment but different substitution profile shows the a-PeT effect. The easy derivatization of phenothiazine fluorophore,
the structure-photophysical property relation and the novel d-PeT fluorescence transduction profile of the phenothiazine based
probes described herein may inspire more investigation into this fascinating research area. 相似文献
180.
Jung A. Jung Young Baek Kim Young A. Kim Seung Bum Ryu Veronica Kim 《Journal of nanoparticle research》2011,13(6):2361-2374
Functional spherical solid and hollow particles of polysilsesquioxanes (PSQs) containing amine, thiol, and vinyl groups were
prepared by polymerizing organotrialkoxysilanes (OTASs) containing corresponding chemical groups. Fluorescent PSQ particles
were prepared by physically entrapping Rhodamine 6G, Coumarin 7, and Fluoresceine sodium salts. The intensity of fluorescent
light increased initially with increasing amount of entrapped fluorophores and then leveled off or decreased slightly after
reaching a maximum value. PSQ particles containing gold nanoparticles (GNPs), both inside and on the surface, were prepared
by the in situ reduction of gold ions by the PSQ particles. When the reduction reaction was carried out for extended periods
of time, the GNP that had formed inside the poly(3-mercaptopropyl)silsesquioxane (PMPSQ) and polyvinylsilsesequioxane (PVSQ)
particles underwent interesting morphological changes. PSQ particles containing amine and thiol groups fixed the GNPs on the
surface, which could be utilized further in binding amine-modified oligo-DNA strands. The aggregation of PSQ/GNP particles
combined with complementary oligo-DNA strands was examined to demonstrate that these particles could be applied to DNA assays
and isolation. The particles were characterized by scanning electron microscopy, transmission electron microscopy, solid state
nuclear magnetic resonance spectroscopy, ultraviolet/visible spectroscopy, and fluorescence microscopy. 相似文献