Synthesis and Structural Studies of 6-（2,5-Dimethyl-1H-pyrrol-1-yl）pyridin-2-amine

6-(2,5-Dimethyl-1H-pyrrol-1-yl)pyridin-2-amine (1) was synthesized and characte-rized by elemental analyses,1H-NMR and 13C-NMR,FTIR,Uv-Vis,mass spectral studies and single-crystal X-ray diffraction.All data obtained from spectral studies support the structural properties of 1.Intermolecular N-H…N hydrogen bonds produce an R22(8) ring.An extensive three-dimensional network formed by C-H…π and N-H…π-facial hydrogen bonds is responsible for the crystal stabilization.The combination of C-H…π interactions produces R33(12),R43(19) and R44(20) rings.     

一类Hartogs域的极小外切Hermite椭球及其对极值问题的应用

构造了一类Hartogs域的具有最小体积的外切Hermite椭球.作为一个应用,得到了从这类Hartogs域到单位球的Carathéodory极值映射.并且给出了计算极值的显式公式.     

Extraction and Purification of Depigmenting Agents from Chinese Plants

Introduction Melaninisaheterogeneousbiopolymerproduced bytheskincells,melanocytes,whichdetermine,mostly,thecoloroftheskin.Excessiveproductionof melaninanditsaccumulationintheskincancausepig mentingdisordersincludingmelasma,solarlentigoand postinflammatory…     

Minimal circumscribed Hermitian ellipsoid of Hartogs domains and an application to an extremal problem

In this paper we construct circumscribed Hermitian ellipsoids of Hartogs domains of least volume and as an application, we obtain the Carath′eodory extremal mappings between the Hartogs domains and the unit ball, and also give an explicit formula for calculating the extremal values.     

Non-isotropic weighted L~p estimates for the -equation on piecewise smooth strictly pseudoconvex domains

In this paper we obtain non-isotropic weighted Lp estimates with the boundary distance weight function for the-equation on piecewise smooth strictly pseudoconvex domains under a hypoth- esis of complex transversality in Cn using the explicit formula of solutions by Berndtsson-Andersson.     

Reconstruction of Rabbit Corneal Layer Composed of Corneal Fibroblasts and Corneal Epithelium on the Lyophilized Amniotic Membrane

Introduction Thehumancornea,animportantopticalcompo nentthatfocusesthelightontheiris,isatransparent avasculartissuethatalsoplaysaprotectiveroleforthe eye.Therefore,anyinjury,diseaseorcelldamagethat canleadtoopacificationofthecornea,canimpairthe vision,and…     

Robust chaos synchronization based on adaptive fuzzy delayed feedback ${\bf{\mathcal{H}}}_{\bf{\infty}}$ control

In this paper, we propose a new adaptive H_￥\mathcal H_\infty synchronization strategy, called an adaptive fuzzy delayed feedback H_￥\mathcal H_\infty synchronization (AFDFHS) strategy, for chaotic systems with uncertain parameters and external disturbances. Based on Lyapunov–Krasovskii theory, Takagi–Sugeno (T–S) fuzzy model and adaptive delayed feedback H_￥\mathcal H_\infty control scheme, the AFDFHS controller is presented such that the synchronization error system is asymptotically stable with a guaranteed H_￥\mathcal{H}_{\infty } performance. It is shown that the design of the AFDFHS controller with adaptive law can be achieved by solving a linear matrix inequality (LMI), which can be easily facilitated by using some standard numerical packages. An illustrative example is given to demonstrate the effectiveness of the proposed AFDFHS approach.     

（E）-1-[4-（2-hydroxy-5-methoxybenzylideneamino）-phenyl]ethanone and （E）-1-[4-（2-hydroxy-4-methoxybenzylideneamino） phenyl]ethanone：X-ray and DFT-calculated structures

The isomeric structures of(E)-1-[4-(2-hydroxy-5-methoxybenzylideneamino)-phenyl] ethanone(I) and(E)-1-[4-(2-hydroxy-4-methoxybenzylideneamino) phenyl]ethanone(Ⅱ) ,both C16H15NO3,have been determined using X-ray diffraction techniques and characterized by IR,and their molecular structures have also been optimized at the B3LYP/6-31G(d,p) level using density functional theory(DFT) . The energetic behaviors of the title compounds in solvent media have been examined using B3LYP method with the 6-31G(d,p) basis set by applying the polarizable continuum model(PCM) . The total energies of the title compounds decrease with the increasing polarity of the solvent. In addition,DFT calculations of the title compounds' molecular electrostatic potentials(MEP) were performed at the B3LYP/6-31G(d,p) level of theory. X-ray study shows that the title compounds both have strong intramolecular O-H…N hydrogen bonds. The molecules of Ⅰ are linked into a one-dimensional framework structure by C-H…π interactions,while in Ⅱ,intermolecular π···π interactions result in the formation of infinite chains running along the [010].     

4-Amino-3-（p-chlorophenyl）-5-（p-methoxybenzyl）-4H-1,2,4-triazole：X-ray and DFT-calculated Structures

The title compound, 4-amino-3-(p-chlorophenyl)-5-(p-methoxybenzyl)-4H-1,2,4- triazole I , C16H15ClN4O), has been determined using X-ray diffraction techniques and the molecular structure has also been optimized at the B3LYP/6-31 G(d, p) level using density functional theory (DFT). The triazole ring exhibits dihedral angles of 41.61(15)o and 80.73(11)o with the phenyl rings. The molecules are linked principally by N–H…N hydrogen bonds involving the amino NH2 group and a triazole N atom, forming C(5) chains which are further linked to give a two-dimensional network of molecules. The N–H…N hydrogen bonding is supported by C–H…N hydrogen bond and C–H…π interaction. Intermolecular N–H…N and C–H…N hydrogen bonds produce R22(9), R44(10) and R44(20) rings.     

A SIMPLE MODEL TO ESTIMATE THE IMPACT FORCE INDUCED BY PISTON SLAP

The dynamics of piston's secondary motion (lateral and rotational motion) across the clearance between piston and cylinder inner wall of reciprocating machines are analyzed. This paper presents an analytical model, which can predict the impact forces and vibratory response of engine block surface induced by the piston slap of an internal combustion engine. A piston is modelled on a three-degree-of-freedom system to represent its planar motion. When slap occurs, the impact point between piston skirt and cylinder inner wall is modelled on a two-degree-of-freedom vibratory system. The equivalent parameters such as mass, spring constant, and damping constant of piston and cylinder inner wall are estimated by using measured (driving) point mobility. Those parameters are used to calculate the impact force and for estimating the vibration level of engine block surfaces. The predicted results are compared with experimental results to verify the model.