Dynamic Inclusion Complexes of Metal Nanoparticles Inside Nanocups

Host–guest inclusion complexes are abundant in molecular systems and of fundamental importance in living organisms. Realizing a colloidal analogue of a molecular dynamic inclusion complex is challenging because inorganic nanoparticles (NPs) with a well‐defined cavity and portal are difficult to synthesize in high yield and with good structural fidelity. Herein, a generic strategy towards the fabrication of dynamic 1:1 inclusion complexes of metal nanoparticles inside oxide nanocups with high yield (>70 %) and regiospecificity (>90 %) by means of a reactive double Janus nanoparticle intermediate is reported. Experimental evidence confirms that the inclusion complexes are formed by a kinetically controlled mechanism involving a delicate interplay between bipolar galvanic corrosion and alloying–dealloying oxidation. Release of the NP guest from the nanocups can be efficiently triggered by an external stimulus.     

Classes of improved estimators for parameters of a Pareto distribution

The problem of estimating parameters of a Pareto distribution is investigated under a general scale invariant loss function when the scale parameter is restricted to the interval (0, 1]. We consider the estimation of shape parameter when the scale parameter is unknown. Techniques for improving equivariant estimators developed by Stein, Brewster–Zidek and Kubokawa are applied to derive improved estimators. In particular improved classes of estimators are obtained for the entropy loss and a symmetric loss. Risk functions of various estimators are compared numerically using simulations. It is also shown that the technique of Kubokawa produces improved estimators for estimating the scale parameter when the shape parameter is known.     

Chemical Processes Involving 18-Crown-6-Ether in Activated Noncovalent Complexes with Protonated Peptides

These last decades, it has been widely assumed that 18-crown-6-ether (CE) plays a spectator role during the chemical processes occurring in isolated host-guest complexes between peptides or proteins and CE after activation in mass spectrometers. Our present experimental and theoretical results challenge this hypothesis by showing that CE can abstract a proton or a protonated molecule from protonated peptides after activation by collisions in argon or electron capture/transfer. Furthermore, thanks to comparison between experimental and calculated values of collision cross-sections, we demonstrate that CE can change binding site after electron transfer. We also propose detailed mechanisms for these processes.     

台阶爆破破碎度的分布规律

本文采用摄影方法在海州露天煤矿对台阶爆破破碎块度进行了测量。根据现场试验所获得的数据,通过多元曲线拟合处理,给出了二种岩石爆破破碎块度的分布规律。所得结论对控制和提高爆破破碎质量具有重要意义。     

软土地基变形的混沌性与承载力识别

本文以混沌理论为基础, 分析了软土地基变形的混沌性态, 并采用映射函数f(x)=ax²+c来拟合软土地基的沉降-载荷曲线。根据映射函数的不动点, 对软土地基加固前后的承载力进行了识别, 并与按相对变形值确定的承载力进行了比较。     

Constitutive equations from Gaussian slip-link network theories in polymer melt rheology

Allowing for flow-dependent slip in the junctions of a temporary junction network, we derive the constitutive equations of temporary slip-link networks. The stress tensor is determined by three material functions, namely, the time-dependent linear-viscoelastic memory function, and two strain-dependent functions describing slip and disentanglement of network strands. Slip and disentanglement are related via a mass balance for network strands.By specifying slip and disentanglement, the constitutive equations of Lodge, Wagner, Doi-Edwards, and Marrucci are shown to be special temporary slip-link constitutive equations. To demonstrate the predictive power of temporary slip-link network theories, we compare predictions and extensional flow data with step change in flow direction.Dedicated to Professor Arthur S. Lodge on the occasion of his 70th birthday and his retirement from the University of Wisconsin.     

Variational solutions for some steady and non-steady laminar viscous flows with stagnation points

Recently, Lebon and Lambermont proposed a general variational principle for fluid mechanics. In this paper, the criterion is applied to steady and non-steady stagnation flows; the plane and the axisymmetrical cases are considered. By using Glansdorff-Prigogine self consistent method, approximate analytic solutions are derived. It is shown that the steady solution is rather quickly reached. For this latter case, the present solutions are compared with previous ones obtained by direct integration of the Navier-Stokes equations.