Space-efficient region filling in raster graphics

This paper presents fill algorithms for boundary-defined regions in raster graphics. The algorithms require only a constant-size working memory. The methods presented are based on the so-called seed fill algorithms that use the internal connectivity of the region with a given inner point. Basic methods, as well as additional hcuristics for speeding up the algorithm, are described and verified. Empirical results are used to compare the time complexities of the algorithms for different classes of regions.     

Metal Single-Site Molecular Complex–MXene Heteroelectrocatalysts Interspersed Graphene Nanonetwork for Efficient Dual-Task of Water Splitting and Metal–Air Batteries

Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (Fe_MC)-carbide MXene (Mo₂TiC₂T_x) uniformly embedded in a 3D graphene-based hierarchical network (GrH) is rationally designed. The coexistence of Fe_MC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the Fe_MC–MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al–air batteries derived from Fe_MC–MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm⁻², respectively. Impressively, the liquid-state Zn–air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm⁻² and 1.86 V at 0.4 A cm⁻² in 30 wt.% KOH at 80 °C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.     

Epitaxial growth and thermal-conductivity limit of single-crystalline Bi2Se3/In2Se3 superlattices on mica

Nano Research - Thermal transport in superlattices is governed by various phonon-scattering processes. For extracting the phonon-scattering contribution of hetero-interfaces in chalcogenide...     

Monitoring the Dynamic Process of Formation of Plasmonic Molecular Junctions during Single Nanoparticle Collisions

The capability to study the dynamic formation of plasmonic molecular junction is of fundamental importance, and it will provide new insights into molecular electronics/plasmonics, single‐entity electrochemistry, and nanooptoelectronics. Here, a facile method to form plasmonic molecular junctions is reported by utilizing single gold nanoparticle (NP) collision events at a highly curved gold nanoelectrode modified with a self‐assembled monolayer. By using time‐resolved electrochemical current measurement and surface‐enhanced Raman scattering spectroscopy, the current changes and the evolution of interfacial chemical bonding are successfully observed in the newly formed molecular tunnel junctions during and after the gold NP “hit‐n‐stay” and “hit‐n‐run” collision events. The results lead to an in‐depth understanding of the single NP motion and the associated molecular level changes during the formation of the plasmonic molecular junctions in a single NP collision event. This method also provides a new platform to study molecular changes at the single molecule level during electron transport in a dynamic molecular tunnel junction.     

基于完全平方数的RSA密码分析算法机理

给出基于完全平方数的RSA密码分析算法的机理,分析满足同余式x2≡y2 (mod n)的完全平方数x和y的数域选择与算法效率的关系。通过数学证明和相关分析方法,定义RSA公钥n的素因子特征c,证明当c>2时,如果数域范围选择和构造的算法得当,则分解n的效率较高,当c<2时,使算法的运算数域增大,可以降低分解n的效率和有效性,即构造的RSA密码是安全的。     

未知环境下移动机器人遍历路径规划

为提高未知环境下移动机器人遍历路径规划的效率,提出了一种可动态调节启发式规则的滚动路径规划算法.该算法以生物激励神经网络为环境模型,通过在线识别环境信息特征,动态调用静态搜索算法和环绕障碍搜索算法,有效减少了路径的转弯次数.引入虚拟障碍和直接填充算法,解决了u型障碍区域的连续遍历问题.最后通过仿真实验表明了该方法在未知复杂环境下的有效性.     

Temperature-controlled molecular dynamics study on velocity-dependent threshold behavior of dynamic nano-friction

Laws of dynamic nano-friction (i.e., continuous wearless friction) were searched for under steady spatial distributions of the local quasi-temperature, by molecular dynamics (MD) simulations. The temperature control of the non-conservative model was carried out by extending the isothermal MD method using the Nosé–Poincaré thermostat. The results suggested that the threshold phenomenon characterizes sliding-velocity dependence of the nano-frictional force between crystal lattices constituting a nano-electromechanical system (NEMS). This phenomenon was turned out to be a universal feature, whether heat transfer to the environment exists or not.     

Development of a linear predictive model for carbon dioxide sequestration in deep saline carbonate aquifers

CO₂ injection into deep saline aquifers is a preferred method for mitigating CO₂ emission. Although deep saline aquifers are found in many sedimentary basins and provide very large storage capacities, several numerical simulations are needed before injection to determine the storage capacity of an aquifer. Since numerical simulations are expensive and time-consuming, using a predictive model enables quick estimation of CO₂ storage capacity of a deep saline aquifer. In order to create a predictive model, the ranges of variables that affect the CO₂ storage capacity were determined from published literature data. Correlations found in literature were used for other important parameters such as pore volume compressibility and density of brine. Latin hypercube space filling design was used to construct 100 simulation cases prepared using CMG STARS. The simulation period covered a total of 300 years of CO₂ storage. By using a least-squares method, linear and nonlinear predictive models were developed to estimate CO₂ storage capacity of deep saline carbonate aquifers. Numerical dispersion effects were considered by decreasing the grid dimensions. It was observed that a dimensionless linear predictive model is better than the nonlinear. The sensitivity analyses showed that the most important parameter that affects CO₂ storage capacity is depth. Most of the (up to 90%) injected gas dissolved into the formation water and a negligible amount of CO₂ reacted with carbonate.     

类弹性蛋白多肽的分子动力学研究

类弹性蛋白多肽因其具有特殊的相变性质,故而在重组蛋白纯化方面展现出良好的应用前景,对其发生相变的机理进行研究具有重要意义.本文利用同源建模的方法构建了类弹性蛋白多肽的三维结构并进行能量优化,之后采用分子动力学模拟手段,在300 K～400 K间5个不同温度下,对含有100个氨基酸残基的类弹性蛋白多肽[KV8F-20]各进行了6 ns的模拟.模拟过程中,类弹性蛋白多肽发生疏水缩聚,初始结构变得更加紧凑,且温度越高折叠程度越大.水分子在类弹性蛋白多肽的相变行为中起到关键作用.经分析,结果发现疏水作用与水的排出在类弹性蛋白多肽发生相变过程中起到关键作用,类弹性蛋白多肽随着温度的升高,在疏水作用驱动下,其构象折叠程度因疏水缩聚而变得更大.此外,比较不同温度下蛋白的缩聚程度,推断类弹性蛋白多肽在375 K左右发生相变,这与实验观测的结果基本吻合.据此,推测该类弹性蛋白多肽变温度范围约为95℃～102℃.这对后续调控类弹性蛋白多肽的相变具有指导作用.     

HEDP及其取代物对碳酸钙阻垢机理的研究

采用分子动力学方法,模拟计算了阻垢剂HEDP及其取代物与方解石(104,(102),(202),(113)面的相互作用,计算并分析了阻垢剂与方解石(104),(102),(202),(113)面作用的相互作用能,包括结合能,库仑能和范德华作用能.并且分析了方解石(104)晶面上的钙离子与阻垢剂中双键氧原子、整个(104)晶面与阻垢剂中所有氧原子之间和整个(104)晶面与整个阻垢剂分子之间的对关联函数,结果表明:阻垢剂分子中的氧原子与碳酸钙的Ca2+形成的离子键对吸附起到了主要作用,同时阻垢剂与晶面间存在较弱的范德华力相互作用,阻垢剂与各晶面的的结合能强弱顺序为(102)＞(202)≥(113)≈(104).苯环的大π键有利于阻垢效果的提高.