A cubic quadrilateral spline element with concave shapes

Basic requirement for applying isoparametric element is that the element has to be convex and no violent distortion is allowed. In this paper, a cubic quadrilateral spline element with 12 nodes has been developed using the triangular area coordinates and the B-net method, which can exactly model the cubic field for quadrilateral element with both convex and concave shapes. Neither mapping nor coordinate transformation is required and the spline element can obtain high accuracy solutions and insensitive to mesh distortions.     

Optimization of highly nonlinear dispersion-flattened photonic crystal fiber for supercontinuum generation

A simple type of photonic crystal fiber (PCF) for supercontinuum generation is proposed for the first time. The proposed PCF is composed of a solid silica core and a cladding with square lattice uniform elliptical air holes, which offers not only a large nonlinear coefficient but also a high birefringence and low leakage losses. The PCF with nonlinear coefficient as large as 46 W 1 · km-1 at the wavelength of 1.55 μm and a total dispersion as low as ±2.5 ps · nm-1 · km-1 over an ultra-broad waveband range of the S-C-L band (wavelength from 1.46 μm to 1.625 μm) is optimized by adjusting its structure parameter, such as the lattice constant Λ , the air-filling fraction f , and the air-hole ellipticity η. The novel PCF with ultra-flattened dispersion, highly nonlinear coefficient, and nearly zero negative dispersion slope will offer a possibility of efficient super-continuum generation in telecommunication windows using a few ps pulses.     

Synthesis, Structures, Fluorescence and Magnetism of Two Lanthanide Metal-organic Frameworks with CaF2 Topology Based on Silicon-centered Tetrahedral Ligand

Two 3D multifunctional lanthanide metal-organic frameworks(MOFs), Pr(HTCPS)(H₂O)·2DMF·C₂H₅OH· 5H₂O(JUC-93) and Pr₃(TCPS)₂(NO₃)(H₂O)₄(DMA)₂·2DMA·C₂H₅OH·3H₂O(JUC-94)[H₄TCPS=tetrakis(4-carboxyphenyl)- silane, DMF=N,N'-dimethylformamide, DMA=N,N'-dimethylacetamide and JUC=Jilin University China] were synthesized by the self-assembly of a rigid silicon-centered tetrahedral carboxylate ligand H₄TCPS and Pr(III) ions in different solvothermal reactions. X-Ray crystallography revealed that they exhibited a rare CaF₂ topology framework, constructed from the 4-connected tetrahedral TCPS unit with the 8-connected dinuclear praseodymium cluster unit and trinuclear praseodymium cluster unit, respectively. In addition, the luminescent and magnetic properties of the two compounds were investigated.     

Syntheses and Supramolecular Structures of Two Nickel(Ⅱ) Compounds Based on Two Thiosemicarbazone Ligands

Two new compounds, [Ni₂(L¹)(Py)₆]Py·CH₃OH(1) and [Ni₃(L²)₂(Py)₄]·2DMF(2)(H₄L¹=N,N'-bisalicyl- bisthiocarbamide; H₃L²=3-hydroxyl-2-naphthalene thiosemicarbazide; Py=pyridine; DMF=dimethyl fumarate), based upon two thiosemicarbazone ligands have been obtained and characterized by elemental analysis, Fourier transform infrared(FTIR) and X-ray diffraction(XRD). Compound 1 possesses a binuclear cluster, in which the bisalicylbisthiocarbamide acts as a hexadentate bridge. Compound 2 exhibits a linear trinuclear cluster with the triply-deprotonated ligand acting as pentadentate bridge. C―H···O, C―H···π and C―H···S weak interactions further link these molecules to form interesting supramolecular networks.     

Approximations and cotorsion pairs related to a tilting pair

The notion of a tilting pair Miyashita in 2001. It is a useful tool in cotorsion pairs related to a fixed tilting （covariantly） finite subcategory and a tilting pair were given in this paper. over artin algebras was introduced by the tilting theory. Approximations and pair were discussed. A eontravariantly eotorsion pair associated with a fixed     

Superconvergence analysis of fully discrete finite element methods for semilinear parabolic optimal control problems

We study the superconvergence property of fully discrete finite element approximation for quadratic optimal control problems governed by semilinear parabolic equations with control constraints. The time discretization is based on difference methods, whereas the space discretization is done using finite element methods. The state and the adjoint state are approximated by piecewise linear functions and the control is approximated by piecewise constant functions. First, we define a fully discrete finite element approximation scheme for the semilinear parabolic control problem. Second, we derive the superconvergence properties for the control, the state and the adjoint state. Finally, we do some numerical experiments for illustrating our theoretical results.     

A New Cooperation Mechanism of Kinesin Motors when Extracting Membrane Tube

Membrane tubes are important functional elements for living cells. Experiments have found that membrane tubes can be extracted from giant lipid vesicles by groups of kinesin. How these motors cooperate in extracting the membrane tube is a very important issue but still unclear so far. In this paper, we propose a cooperation mechanism called two-track-dumbbell model, in which kinesin is regarded as a dumbbell with an end (tail domain) tethered on the fluid-like membrane and the other end (head domain) stepping on the microtubule. Taking account of the elasticity of kinesin molecule and the excluded volume effect of both the head domain and the tail domain of kinesin, which are not considered in previous models, we simulate the growth process of the membrane tube pulled by kinesin motors. Our results indicate that in the case of strong or moderate exclusion of motor tails, the average number of motors pulling the tube can be as high as 9 and thus motors moving along a single microtubule protofilament can generate enough force to extract membrane tubes from vesicles. This result is different from previous studies and may be tested by future experiments.     

樟脑酸衍生物构筑的单一手性金属有机骨架化合物的合成、表征及荧光性质

设计合成了一个新的手性樟脑酸衍生物[D-H₂ctba, H₂ctba=4-(3-羧基-2,2,3-三甲基环戊烷酰胺)苯甲酸]. 将其作为配体与硝酸镉通过溶剂热反应得到了新的手性金属有机骨架化合物[Cd₃(ctba)₃·H₂O]_n(1). 通过单晶X射线衍射(XRD)、 粉末X射线衍射(PXRD)、 元素分析、 热重分析(TGA)和圆二色(CD)光谱对该化合物进行了表征. 单晶结构解析表明, 该化合物具有单一手性结构, 以1个六核的Cd羧基簇为基本单元, 簇与簇之间通过羧基相连形成(-Cd-O-C-)_∞棒状次级结构单元, 次级结构单元之间由配体相连, 拓展成为三维的骨架结构. 荧光光谱测试结果表明, 该化合物在室温下具有较强的荧光性质.     

Numerical solutions to regularized long wave equation based on mixed covolume method

The mixed covolume method for the regularized long wave equation is developed and studied. By introducing a transfer operator γh , which maps the trial function space into the test function space, and combining the mixed finite element with the finite volume method, the nonlinear and linear Euler fully discrete mixed covolume schemes are constructed, and the existence and uniqueness of the solutions are proved. The optimal error estimates for these schemes are obtained. Finally, a numerical example is provided to examine the efficiency of the proposed schemes.     

调节索氏抽提器抽提液量的2种措施

介绍了调节索氏抽提器抽提液量的2种措施,第1种是在原有提取管中加一可置入玻璃垫块的框架,第2种是在提取管壁上设置可搁置玻璃垫块的支撑凸点.2种措施均通过增减玻璃垫块的数量来调节抽提液量.