Supramolecular catalytic systems based on anionic amphiphiles and polyethyleneimine for hydrolytic cleavage of phosphorus ester bonds

Self-organization in individual and binary systems based on polyethyleneimine (PEI) and amphiphilic sulfonatocalix[4]resorcinarene was studied by conductometry, tensiometry, dynamic light scattering, and ¹H NMR spectroscopy. The critical concentrations of micelle formation and aggregate sizes were determined. The enhancement of the catalytic effect on the hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate was shown in the following series of the systems: PEI-water < PEI—calixarene-water < PEI—calixarene—La^III—water. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 366–373, February, 2008.     

The strain relaxation of InAs/GaAs self-organized quantum dot

This paper presents a detailed analysis of the dependence of degree of strain relaxation of the self-organized InAs/GaAs quantum dot on the geometrical parameters. Differently shaped quantum dots arranged with different transverse periods are simulated in this analysis. It investigates the total residual strain energy that stored in the quantum dot and the substrate for all kinds of quantum dots with the same volume, as well as the dependence on both the aspect ratio and transverse period. The calculated results show that when the transverse period is larger than two times the base of the quantum dots, the influence of transverse periods can be ignored. The larger aspect ratio will lead more efficient strain relaxation. The larger angle between the faces and the substrate will lead more efficient strain relaxation. The obtained results can help to understand the shape transition mechanism during the epitaxial growth from the viewpoint of energy, because the strain relaxation is the main driving force of the quantum dot's self-organization.     

Controlled Thermosensitivity of the Poly(N-isopropyl- acrylamide-co-N,N′-dimethyl(methacryloyloxyethyl)- ammonium propane sulfonate) Hydrogels

Summary : The N-isopropylacrylamide (NIPAM) and N,N′-dimethyl-(methacryloyloxyethyl) ammonium propane sulfonate (DMAPS) copolymer networks having monomer units with an opposite thermoassembling ability are synthesized and analyzed. The network composition is of crucial importance for their degree of swelling (Q) and Q-Temperature (T) dependences. After the Q normalization these dependences outline two classes of networks which hydrogels expel or imbibe water with T. The boundary network (with 0.39 mole fraction of DMAPS monomer units) defines a critical T (T_cr) at which Q is the same as that at the initial T (T_o), but with a structure organization, different than that at T_o. The hydrogels thermoreversibility at the stepped T change, and the salt effect on the Q-T dependences are demonstrated also.     

A realistic model for complex networks with local interaction,self-organization and order

In this paper, a new mechanism for the emergence of scale-free distribution is proposed. It is more realistic than the existing mechanism. Based on our mechanism, a model responsible for the scale-free distribution with an exponent in a range of 3-to-5 is given. Moreover, this model could also reproduce the exponential distribution that is discovered in some real networks. Finally, the analytical result of the model is given and the simulation shows the validity of our result.     

红外光谱评价内燃机油抗氧化性能的研究

红外光谱快速检测石油产品性能是近年来发展的新技术,目前国内外在该领域的研究仅限于测试燃料油性能,由于润滑油组成、结构复杂,红外光谱技术测试润滑油性能的研究还未见报道。文章研究了润滑油组成、结构的红外光谱特征,提出了根据内燃机油组成、结构对抗氧化性能的贡献来提取其光谱信息的技术路线。结合BP神经网络和自组织神经网络的优点,发展了量化自组织神经网络数学模型,该数学模型具有自组织神经网络的定性聚类功能和BP神经网络的定量分析功能,与BP神经网络相比较,量化自组织神经网络具有更好的鲁棒性,测试结果优于BP神经网络,该论文的研究为润滑油性能的快速检测提供了一种新的技术手段。     

Three-dimensional photonic crystal structures achieved with self-organization of colloidal particles

Three-dimensional polystyrene/air photonic crystal structure with different particle diameters: 200, 270 and 340 nm was achieved. Strong photonic band gap effect reflected with transmission minimum down to –16 dB was observed. The central wavelengths of the valleys of spectra were well fitted with theoretical calculation. The augmentation of band gap effect versus particle diameter was attributed to an improved self-assembling of particles. An analysis of transmission spectra is also presented. The agreement between the results of experiment and numerical analysis is good.     

Social influence in small—world networks

We report on our numerical studies of the Axelrod model for social influence in small-world networks.Our simulation results show that the topology of the network has a crucial effect on the evolution of cultures .As the randomness of the network increases,the system undergoes a transition from a highly fragmented phase to a uniform phase.we also find that the power-law distribution at the transition point,reported by castellano et al,is not a critical phenomenon;it exists not only at the onset of transition but also for almost any control parameters,All these power-law distributions are stable against pertubations.A mean-field theory is developed to explain these phenomena.     

Periodic Nucleation of Calcium Phosphate in a Stirred Biocatalytic Reaction

Highly ordered superstructures composed of inorganic nanoparticles appear in natural and synthetic systems, however the mechanisms of non‐equilibrium self‐organization that may be involved are still poorly understood. Herein, we performed a kinetic investigation of the precipitation of calcium phosphate using a process widely found in microorganisms: the hydrolysis of urea by enzyme urease. With high initial ratio of calcium ion to phosphate, periodic precipitation was obtained accompanied by pH oscillations in a well‐stirred, closed reactor. We propose that an internal pH‐regulated change in the concentration of phosphate ion is the driving force for periodicity. A simple model involving the biocatalytic reaction network coupled with burst nucleation of nanoparticles above a critical supersaturation reproduced key features of the experiments. These findings may provide insight to the self‐organization of nanoparticles in biomineralization and improve design strategies of biomaterials for medical applications.     

平面环行交叉路口交通流的研究

从道路结构出发,对具有内、外环道的平面环形交叉路口建立了具有多个道路瓶颈的元胞自动机模型,对平面环行交叉路口的交通流进行研究.计算机模拟结果表明,环形交叉路口的内环道中与入环车道接壤处是最容易发生阻塞的地方,内环道中车辆之间的非线性相互作用的效应随刹车概率的增大而增强,流量随之减小;而转向概率的增加有助于提高系统交通流量. 关键词： 平面环形交叉路口 元胞自动机模型 瓶颈 自组织     

Toward model-driven engineering of supramolecular copolymers

The coassembly of two oligo-(p-phenylene vinylene) (OPV) derivatives with different sizes and opposite chirality is studied. Short R-chiral ROPV₃ molecules experience a high energetic mismatch penalty when incorporated in helices formed by long S-chiral SOPV₄ molecules. In contrast, SOPV₄ easily coassembles into helices dominated by ROPV₃. As a result, the coassembly behavior (i.e., mixing or phase separation of ROPV₃ and SOPV₄ within the assemblies) highly depends on the ratio between both molecular building blocks. By a combination of experiments and models, the assembly pathways are analyzed. Furthermore, the model allows identifying key parameters in the coassembly behavior, such as the cooperativity and the mismatch penalties. The model-driven approach is anticipated to be generally applicable in the engineering of functional supramolecular copolymers. This article is dedicated to the 70th birthday of Jean Fréchet and we thank him for being a continuous source of inspiration for our group. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 385–391