SZOLD: Its Properties and Relationship to Other Distributions

SZOLD is a form of the three-parameter lognormal distribution. As originally defined, its normalization factor permits negative values of the distributed variable for some positively skewed distributions and for all negatively skewed distributions. Correct normalization factors are given here, and the degree of truncation is shown as a function of the distribution parameters.     

Controlled processing of polymer nanoribbons: Enabling microhelix transformations

Flow‐coated, two‐dimensional polymer ribbon structures undergo a shape‐transformation into a three‐dimensional helix upon their release into a solution. Driven by surface forces and due to geometric asymmetry, the helix radius and spring constant depend upon the ribbon cross‐section dimensions, surface energy, and material elastic modulus. Such spring‐like microhelices offer multiple functionalities combined with mechanical stretching and shape recovery. Fabricating such microhelices requires a sequence of processing steps, beginning with flow‐coating of ribbons on a substrate, followed by etching of a “scum layer” to allow for an independent release into a solution, upon which shape‐transformation occurs. During the deposition‐etch‐release sequence, various control parameters influence the nanoribbon size and geometry, hence the helix properties. The experimental study presented here focuses on the influence of meniscus height, substrate velocity, substrate surface energy, and etch time on nanoribbon size (height and width), scum layer thickness, and helix radius. The results show that meniscus height and contact angle dictate flux toward the meniscus edge and volume available for spatial assembly, allowing control over the aspect ratio of ribbons. We vary the aspect ratio by two orders of magnitude, while maintaining geometric asymmetry needed for helix shape‐transformation. We provide robust scaling for the nanoribbon size and geometry and report the advantages and disadvantages of different parameters, in the control of polymer nanoribbon and helix fabrication. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1270–1278     

Stimuli‐Responsive Dipeptide–Protein Hydrogels through Schiff Base Coassembly

Different from the conventional irreversible covalent conjugations, a simple and efficient dynamic Schiff base covalent assembly is developed to construct the stable and smart dipeptide–protein hydrogels under mild conditions. Diphenylalanine–hemoglobin hydrogel is chosen to investigate the gelation formation process and mechanism. It is found that such assembled dipeptide–protein hydrogels are sensitive to pH variation, and simultaneously the proteins can be released without changing the native secondary structures from the gels. Furthermore, these adaptive hydrogels can encapsulate a series of small molecules, multicomponent proteins, and functional nanoparticles. These versatile hydrogels may find a great potential in bioapplications.     

大尺寸石墨烯量子点组装体的制备及电化学发光性能

对氧化石墨烯纳米材料进行HNO₃氧化处理, 制备了水溶性好且具有强电化学发光(ECL)活性的大尺寸石墨烯量子点组装体(Large-sized graphene quantum dot assemblies, LSGQD-NAs). 利用透射电子显微镜(TEM)、 原子力显微镜(AFM)、 傅里叶变换红外光谱(FTIR)和拉曼光谱(Raman)等方法对其进行了表征, 结果表明, 石墨烯量子点组装体的平均高度为20 nm, 且富含大量的羟基和羧基. 电化学测试结果显示, 在共反应物K₂S₂O₈存在下, LSGQD-NAs在阴极产生很强的ECL(峰值约在685 nm); 并推测了其ECL反应机理, 发现LSGQD-NAs容易通过中心未氧化的石墨烯π-π作用于GC电极表面进行组装修饰. 本研究为基于石墨烯量子点ECL传感器的研究提供了新方法.     

The Panel Method for Rigid Section Group Added Mass Coefficients and Its Application to Fuel Assemblies北大核心CSCD

A numerical method based on the panel method was developed to calculate the added fluid mass coefficients of the rigid section group with arbitrarily complex shapes, and was successfully applied to the PWR fuel assemblies. The variation law of added mass coefficients with position deviations was analyzed in the seismic test of 1×5 fuel assemblies. The results show that, this method is suitable for the calculation of the added mass coefficients of rigid section groups with complex continuous boundaries. Compared with the gap between assemblies, the gap between baffles and assemblies has a dominant influence on the added mass coefficient. Regardless of the position deviation, the sum of the added mass coefficients of all assemblies and baffles in the assumed motion direction is approximately equal to –1, and that in the perpendicular direction is approximately equal to 0. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

Breakthrough and future: nanoscale controls of compositions,morphologies, and mesochannel orientations toward advanced mesoporous materials

Currently, ordered mesoporous materials prepared through the self‐assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic‐based materials, for example, transition‐metal oxides, carbons, inorganic‐organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant‐based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation‐mediated direct templating (EDIT), spray‐dried techniques, and collaboration with hard‐templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic‐scale controls of mesochannels are important for innovative applications such as molecular‐scale devices and electrodes with enhanced diffusions of guest species. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 321–339; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900022     

Electrochemical and Surface Properties of Multilayer Films Based on a Ru2+ Metallodendrimer and the Mixed Addenda Dawson Heteropolyanion

The successful formation of organized multilayer assemblies, formed from the Dawson type mixed addenda heteropolyanion, [P₂W₁₇ V^IVO₆₂]^8?, and a Ru²⁺ pentaerythritol based metallodendrimer, [RuDen]⁸⁺, has been achieved on carbon electrode surfaces. Cyclic voltammetric studies of the assembly across a wide pH domain, namely, 2 to 7 was possible. Upon redox switching, the redox couples associated with the Ru^III/II redox system, of the cationic metallodendrimer, and both the V^IV/V and the tungsten‐oxo framework of the heteropolyanion, were clearly evident. The multilayer assembly exhibited good stability towards both redox cycling and soaking over extended periods of time in aqueous buffer solutions. In addition, the constructed multilayer films were found to be quite compact in nature. The films were further characterized by X‐ray photoelectron spectroscopy (XPS) to determine their elemental composition. Surface morphology of the multilayer films was determined by atomic force microscopy (AFM). The electrocatalytic reduction of iodate by the multilayer film was also investigated.     

Structure of 2-(1-phenylimidiazolidin-2-ylidene)- malononitrile and 2-(hexahydropyrimidinyl-2-ylidene)- malononitrile

The crystal structure of 2-(1-phenylimidazolidin-2-ylidene)-malononitrile, I, and 2-(hexahydropyrimidin-2-ylidene)-malononitrile, II, were determined with crystal data (I: Monoclinic, P2₁/n, a=8.116(3) ?, b=7.650(3) ?, c=17.399(7) ?, β=93.065(6)°, R _all=0.0980; II: Monoclinic, P2₁/n, a=9.169(2) ?, b=8.103(2) ?, c=10.337(3) ?, β=99.853(4)°, R _all=0.0877). N−H···N hydrogen bonds were responsible for the formation of centrosymmetric dimers of I and one-dimensional zigzag molecular chains of II.