Relationship Between Molecular Structure,Single crystal Packing and Self-Assembly Behavior: A Case Based on Pyrene Imide Derivatives

Development of new n-type one-dimensional (1D) self-assembly nanostructure and a clear understanding of the relationship between molecular structure and self-assembly behavior are important prerequisites for further designing and optimizing organic optoelectronic nanodevice. In this article, a series of n-type organic semiconductor materials based on pyrene imide were successfully synthesized through [4+2] cycloaddition reactions and their preliminary optical and electrochemical properties were studied. The simulated HOMO-LUMO bandgaps via DFT tallied with the experimental data well. The self-assembly of these materials showed needle or fiber-like morphologies, indicating that different conjugation degree or alkyl group had significant influence on their self-assembly behaviors. Furthermore, the single-crystal packing for these molecules were analyzed and it was found out that the changes of conjugated backbone and functional group would affect certain crystal lattice parameter significantly, such as the intermolecular packing distance and crystal size etc, which would further result in different self-assembly morphology.     

Ground State Phases of Spin-Orbit Coupled Spin-1 Dipolar Bose-Einstein Condensates

International Journal of Theoretical Physics - The ground state phases of spin-1 Bose-Einstein condensates with Rashba spin-orbit coupled (SOC) and dipole-dipole interaction (DDI) are studied....     

一种结构动力时程分析的积分求微方法

传统采用微分求积(differential quadrature,DQ)法求解动力问题时都是以位移响应作为基本未知量,而将速度响应和加速度响应表示为位移响应的加权和的形式.如此做法需要处理线性方程组或者矩阵方程(Sylvester方程)才能求得动力响应,导出的算法一般为有条件稳定算法.本文利用动力响应的Duhamel积分解,逆用DQ原理,提出了一种计算卷积的高精度显式算法.该算法可以逐时段地求解出动力时程响应,当各时段内DQ节点分布完全一致时,仅须进行一次Vandermonde矩阵求逆计算即可应用于各个时段,一次性获得时段内多个时刻的位移响应值,因而具有计算效率高的优点.通过分析动力方程积分格式,证明本文动力算法传递矩阵的谱半径恒等于1,因而该算法具有无条件稳定特性,且计算过程中不会产生数值耗散. 本文算法的数值精度取决于分析时段内布置的DQ节点数量$N$,具有$N-1$阶代数精度.实际操作时可以取10个甚至更多的DQ节点数,从而获得比较高的数值精度.      

All-metal layer-by-layer films: bimetallic alternate layers with accessible mesopores for enhanced electrocatalysis

We have prepared multilayer mesoporous bimetallic (Pt/Pd) alternating films by layer-by-layer (LbL) electrochemical deposition. Because of the high surface area and heterometallic interfacial atomic contacts, enhanced electrocatalytic activity for methanol oxidation reaction is realized. This novel LbL approach allows optimization of the electrocatalytic performance through precise tuning of the thickness of each layer.     

Exploring the structure–property relationships of ultrasonic/MRI dual imaging magnetite/PLA microbubbles: magnetite@Cavity versus magnetite@Shell systems

Two types of magnetite/PLA composite microbubbles with different magnetite loading sites (magnetite nanoparticles [MNPs] were loaded in shell or core part), named as Fe₃O₄@Shell and Fe₃O₄@Cavity microbubbles, were respectively fabricated by an improved W₁/O/W₂ double emulsification approach and by an interfacial coprecipitation joint double emulsification approach. The preparation parameters were crucial factors for controlling the morphologies and structures of the microbubbles. To clarify the relationship between their structural characteristics and their properties, the T ₂-weighted magnetic resonance imaging (MRI) capabilities as well as the sound attenuation behavior of the microbubbles were investigated. The results demonstrate that the encapsulation of MNPs in either the inner cavity or the shell provides improved sound attenuation, the two types of microbubbles provide comparable sound attenuation enhancement properties, whereas Fe₃O₄@Shell microbubbles exhibit better T ₂-weighted MRI capabilities. The T ₂ relaxation time decreased from 219.5 to 62.1?ms for the Fe₃O₄@Cavity microbubbles and from 163.8 to 45.7?ms for the Fe₃O₄@Shell microbubbles, as the iron concentration increased from 0.05 to 1?mM. In addition, both types of microbubbles exhibit no cytotoxicity to either NRK or BRL-3A metabolic cell cultures. These results suggest that these magnetite-containing microbubbles have great potential as ultrasonic/MR dual contrast imaging agents.     

Facile synthesis of hollow polymeric microparticles possessing various morphologies via seeded polymerization

In this paper, hollow poly(styrene-co-divinylbenzene-co-methacrylic acid) microparticles possessing various morphologies were synthesized by a combination of seeded polymerization and SPG membrane emulsification. Three families of polystyrene (PS) microspheres with various molecular weights but similar diameters were fabricated by SPG membrane emulsification. These PS microspheres were used as seeds to investigate the effect of their molecular weight on the phase separation between the PS seeds and microgel-like networks formed during seeded polymerization and on the morphologies of the resultant particles. Our study revealed that three resultant microparticles possessed diameters of ca. 10?μm and hollow cavities. The shell thickness of the particles became thinner as M _w increased from 3.5?×?10⁴ to 28.0?×?10⁴. The morphological evolution of the microparticles during seeded polymerization was monitored, and these results verified the influence of the molecular weight of the PS seeds on the phase separation behavior and hence the morphologies of the resultant particles.     

Chiral Carbonaceous Nanotubes Containing Twisted Carbonaceous Nanoribbons,Prepared by the Carbonization of Chiral Organic Self‐Assemblies

Single‐handed helical silica nanotubes containing chiral organic self‐assemblies were prepared by using a supramolecular templating approach. After carbonization and the removal of the silica, single‐handed helical carbonaceous nanotubes that contained twisted carbonaceous nanoribbons were obtained. It is believed that the nanotubes formed as a result of the adsorption of low‐molecular‐weight gelators. The twisted nanoribbons were formed because of the carbonization of the organic self‐assemblies. The samples were characterized by using field‐emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, and circular dichroism. For the samples carbonized at 900 °C for 3.0 h, a partially graphitized structure was identified. The circular dichroism (CD) spectra indicated that the twisted nanoribbons exhibited optical activity. The CD spectrum was simulated by using time‐dependent density functional theory. The results suggested that the CD signals originated from the chiral stacking of aromatic rings.     

Infinite time gradient blow-up for parabolic prescribed mean curvature equations

We prove some results on the existence of infinite time gradient blow-up phenomena for parabolic prescribed mean curvature equations over bounded, mean-convex domains in Rⁿ$R^n$.