Kinetics of catalytically activated duplication in aggregation growth

We propose a catalytically activated duplication model to mimic the coagulation and duplication of the DNA polymer system under the catalysis of the primer RNA. In the model, two aggregates of the same species can coagulate themselves and a DNA aggregate of any size can yield a new monomer or double itself with the help of RNA aggregates. By employing the mean-field rate equation approach we analytically investigate the evolution behaviour of the system. For the system with catalysis-driven monomer duplications, the aggregate size distribution of DNA polymers a_k(t) always follows a power law in size in the long-time limit, and it decreases with time or approaches a time-independent steady-state form in the case of the duplication rate independent of the size of the mother aggregates, while it increases with time increasing in the case of the duplication rate proportional to the size of the mother aggregates. For the system with complete catalysis-driven duplications, the aggregate size distribution a_k(t) approaches a generalized or modified scaling form.     

反应限制聚集模型的动力学行为的研究

根据反应限制聚集（reaction limited aggregation, RLA）模型,研究表面活性剂存在时 的薄膜外延生长动力学过程. 研究结果表明,在二维岛的生长初期,分形岛与紧致岛具有不 同的岛密度和“死”原子密度（岛的相对总面积）增长方式：分形岛密度随覆盖率生长指数 小于1,紧致岛密度的生长指数大于1;分形岛相对总面积随覆盖率线性增长,紧致岛相对总 面积随覆盖率非线性增长. 关键词： 反应限制聚集模型 岛密度 “死”原子密度     

Critical behavior of a dynamical percolation model

The critical behavior of the dynamical percolation model, which realizes the molecular-aggregation conception and describes the crossover between the hadronic phase and the partonic phase, is studied in detail. The critical percolation distance for this model is obtained by using the probability P∞ of the appearance of an infinite cluster. Utilizing the finite-size scaling method the critical exponents γ/v and T are extracted from the distribution of the average cluster size and cluster number density. The influences of two model related factors, I.e. The maximum bond number and the definition of the infinite cluster, on the critical behavior are found to be small.     

Critical behavior of a dynamical percolation model

The critical behavior of the dynamical percolation model,which realizes the molecular-aggregation conception and describes the crossover between the hadronic phase and the partonic phase,is studied in detail. The critical percolation distance for this model is obtained by using the probability P∞ of the appearance of an infinite cluster. Utilizing the finite-size scaling method the critical exponents γ/ν and τ are extracted from the distribution of the average cluster size and cluster number density. The influences of two model related factors,i.e. the maximum bond number and the definition of the infinite cluster,on the critical behavior are found to be small.     

Scaling behavior in a proportional voting process

We perform a statistical analysis on the proportional elections held in Brazil in October 1998. We show that the distribution of votes among candidates for the whole country follows a power law N(v) is proportional to v(-alpha), with alpha=1.00+/-0.02, extending over two orders of magnitude. The voting distributions for several states of the federation also display scale-invariant behavior with alpha approximately equal to 1. We argue that this particular voting system can be modeled as a typical multiplicative process in which the choice of the candidate is governed by a product of probabilities.     

Luminescent properties of thermally activated delayed fluorescence molecule with intramolecular π-π interaction between donor and acceptor

Influence of intramolecular π-π interaction on the luminescent properties of thermally activated delayed fluorescence(TADF) molecule(3, 5-bis(3,6-di-tert-butyl-9 H-carbazol-9-yl)-phenyl)(pyridin-4-yl) methanone(DTCBPY) is theoretically studied by using the density functional theory(DFT) and time-dependent density functional theory(TD-DFT).Four conformations(named as A, B, C, and D) of the DTCBPY can be found by relax scanning, and the configuration C corresponds to the luminescent molecule detected experimentally. Besides, we calculate the proportion of each conformation by Boltzmann distribution, high configuration ratios(44% and 52%) can be found for C and D. Moreover, C and D are found to exist with an intramolecular π-π interaction between one donor and the acceptor; the intramolecular interaction brings a smaller Huang-Rhys factor and reduced reorganization energy. Our work presents a rational explanation for the experimental results and demonstrates the importance of the intramolecular π-π interaction to the photophysical properties of TADF molecules.     

Discovery of a herbicidal lead using polymer-bound activated esters in generating a combinatorial library of amides and esters

Summary A combinatorial library containing mixtures of amides and esters was prepared through solid-phase chemistry. The advantages of using solid-phase chemistry over solution-phase chemistry to prepare this library are discussed. The library was screened through a high-throughput whole organism herbicidal assay upon which a mixture containing amides was found to have herbicidal activity. Deconvolution of the mixture providedN-(3-benzoylphenyl)-3-(1,1-dimethylethyl)-1-methyl)-1H-pyrazole-5-carboxamide as a herbicidal lead with broadleaf and narrowleaf pre-emergence herbicidal activity as low as 100 g/ha on some weed species. This study represents the first report of an agrochemical discovered using a combinatorial approach. Supplementary Material, comprising experimental procedures for the preparation of resin II and the reaction of II with nucleophiles, GC/MS and LC/MS data for the reaction ofII with morpholine, and a detailed experimental for the preparation of 2 with characterization data, is available upon request.     

Development of a novel electric field-assisted modified hydrodynamic cavitation system for disintegration of waste activated sludge

In this current study, we present a modified hydrodynamic cavitation device that combines an electric field to substitute for the chemical addition. A modified HC system is basically an orifice plate and crisscross pipe assembly, in which the crisscross pipe imparts some turbulence, which creates collision events. This study shows that for maximizing disintegration, combining HC system, which called electric field-assisted modified orifice plate hydrodynamic cavitation (EFM-HC) in this study, with an electric field is important. Various HC systems were compared in terms of disintegration of WAS, and, among them, the EFM-HC system exhibited the best performance with the highest disintegration efficiency of 47.0 ± 2.0% as well as the destruction of WAS morphological characteristics. The experimental results clearly show that a conventional HC system was successfully modified. In addition, electric field has a great potential for efficient disintegration of WAS for as a additional option in a combination treatment. This study suggests continued research in this field may lead to an appropriate design for commercial use.     

Evolution of large-scale correlations in a strongly nonequilibrium Bose condensation process

The evolution of off-diagonal correlation functions (for the example of a single-particle density matrix) in the process of Bose condensation of an initially nonequilibrium interacting gas is discussed. Special attention is given to the character of the decay of the density matrix at distances much greater than the size of the quasicondensate region. Specifically, it is shown that the exponential decay of the density matrix necessarily presupposes the presence of a chaotic vortex structure — a tangle of vortex lines — in the system. When topological order is established but there is no off-diagonal long-range order, the density matrix decays with distance according to a power law. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 495–501 (10 April 1998)     

Scaling solutions of Smoluchowski's coagulation equation

We investigate the structure of scaling solutions of Smoluchowski's coagulation equation, of the formc _k (t)s(t)^– (k/s(t)), wherec _k (t) is the concentration of clusters of sizek at timet,s(t) is the average cluster size, and(x) is a scaling function. For the rate constantK(i, j) in Smoluchowski's equation, we make the very general assumption thatK(i, j) is a homogeneous function of the cluster sizesi andj:K(i,j)=a ^– K(ai,aj) for alla>0, but we restrict ourselves to kernels satisfyingK(i, j)/j0 asj. We show that gelation occurs if>1, and does not occur if1. For all gelling and nongelling models, we calculate the time dependence ofs(t), and we derive an equation for(x). We present a detailed analysis of the behavior of(x) at large and small values ofx. For all models, we find exponential large-x behavior: (x)A x ^– e ^–x asx and, for different kernelsK(i, j), algebraic or exponential small-x behavior: (x)Bx ^– or (x)=exp(–Cx ^–|| + ...) asx0.     

运动级联型三能级原子双光子过程的熵演化

研究了运动级联型三能级原子与单模场双光子相互作用过程中场(原子)熵的演化特性. 讨论了当运动原子初始处于相干叠加态时,原子运动、场模函数、初始场的平均光子数n对场熵演化的影响. 结果表明：熵演化的周期依赖于原子的运动和场模函数的取值,而初始场的平均光子数n只影响最大和次最小熵值,不改变熵演化的周期. 关键词： 双光子 运动Ξ型三能级原子 熵     

1 and 2-Photon Fluorescence Anisotropy Decay to Probe the Kinetic and Structural Evolution of Sol-Gel Glasses: A Summary

We review recent 1- and 2-photon fluorescence studies of the formation dynamics and structure of sol-gel glasses, from nanometre-sized particles to clusters, prepared from both aqueous silicates and tetramethylorthosilicate (TMOS), over a broad pH range. Through the careful choice of a fluorescent probe, anisotropy decay has been shown to provide both silica particle size and viscosity information and offers advantages over traditional techniques for silica particle sizing based on small-angle neutron, Xray, or light scattering. Subsequently, we are now able to observe the self-assembly mechanisms (or recently termed kinetic life history) of silica, produced under both acidic and alkaline conditions from sodium silicate solution (water glass) in the case of hydrogels and from alkoxides in the case of alcogels. The controlled preparation of hydrogels, often deemed a blackart, is also discussed in some detail, as are the potential applications and benefits of fluorescence anisotropy decay to industrial sol-gel systems. The insight into the sol-gel process provided by these new interpretations of fluorescence decay data, promises to have implications for both our fundamental understanding and the production of sol-gel systems in general.     

Evolution dynamics of initial coherent states of a field in an unstable region of the behavior in the process of intracavity third harmonic generation

The quantum dynamics of the state of a field is studied for the process of intracavity third harmonic generation in the region of unstable behavior of the system in the case in which the interacting modes are developed from initial coherent states. It is shown that the Wigner functions of the states of the modes and mean values of the quadrature amplitudes of the fields can have oscillations disappearing with the transition of the system to a stable region.     

Coupling effect of Brownian motion and laminar shear flow on colloid coagulation:a Brownian dynamics simulation study

Simultaneous orthokinetic and perikinetic coagulations(SOPCs) are studied for small and large Peclet numbers(P e) using Brownian dynamics simulation.The results demonstrate that the contributions of the Brownian motion and the shear flow to the overall coagulation rate are basically not additive.At the early stages of coagulation with small Peclet numbers,the ratio of overall coagulation rate to the rate of pure perikinetic coagulation is proportional to P 1/2 e,while with high Peclet numbers,the ratio of overall coagulation rate to the rate of pure orthokinetic coagulation is proportional to P 1/2 e.Moreover,our results show that the aggregation rate generally changes with time for the SOPC,which is different from that for pure perikinetic and pure orthokinetic coagulations.By comparing the SOPC with pure perikinetic and pure orthokinetic coagulations,we show that the redistribution of particles due to Brownian motion can play a very important role in the SOPC.In addition,the effects of redistribution in the directions perpendicular and parallel to the shear flow direction are different.This perspective explains the behavior of coagulation due to the joint effects of the Brownian motion(perikinetic) and the fluid motion(orthokinetic).     

The effect of rf power on the growth of InN films by modified activated reactive evaporation

We report the effect of rf power on the structural, optical and electrical properties of InN films grown by modified activated reactive evaporation. In this technique, the substrates were kept on the cathode instead of ground electrode. The films grown at higher rf power shows preferential c-axis orientations for both silicon and glass substrates. The films prepared at 100 W show best structural, electrical and optical properties. The c-axis lattice constant was found to decrease with increase in rf power which can be attributed to reduction in excess nitrogen in the films. The band gap decreases with increase in rf power due to Moss-Burstein shift. The decrease in carrier concentration and optical band gap with increase in rf power can also be related to excess nitrogen in the film. The Raman spectra shows a red shift in the A₁(LO) and E₂ (high) mode from the reported value. The possible origin of the present large band gap is due to Moss-Burstein shift. The new film growth method opens opportunities for integrating novel substrate materials with group III nitride technologies.     

The interaction mechanism of mechanical activated energetic composites

Herein, in order to study the interaction mechanism of mechanical activated energetic composites, molecular dynamics simulation was carried out to calculate the binding energy and the interaction mode of PTFE with different crystalline surfaces of Al and Al₂O₃. Then the mechanical activated energetic composites were prepared, the microscopic morphology and the surface element content of Al-PTFE composites before and after mechanical activation have been studied. At last, the reactivity was tested. The results show that the adsorption of PTFE on the (0 0 1), (0 1 0) and (1 0 0) surface of Al₂O₃ and Al is stable. PTFE interacts with Al₂O₃ mainly via electrostatic force, and PTFE interacts with Al mainly via Van der Waals’ force. After 40 min ball milling, Al and PTFE melt into a composite aggregate, the adsorption of PTFE on the surface of Al and Al₂O₃ is stable, the experimental results are in good agreement with the simulation results. Mechanical activation can remarkably reduce the diffusion distance, improve the reaction activity and the detonation velocity of Al-PTFE composites.