Higher order structures and toughening mechanisms for simultaneously polymerized polymethacrylate/polyurethane

Amorphous polymer/crystalline polymer blends can be prepared via the simultaneous polymerization of polymethacrylate/polyurethane combinations. The relationship between higher order structures and fracture mechanisms in these blends must be uncovered to elucidate the source of the increased fracture toughness of such materials. The present work involves the production of blended polymethacrylate/polyurethane and assess the internal structures of these specimens using optical and electron microscopy. These observations reveal the presence of both spherulites and elastomeric phases. The spherulites consisting of the polyurethane and are several micrometers in diameter whereas the phase-separated polyurethane elastomeric domains are approximately 100 nm in size. Multiple cracks, crack bridging and plastic deformation around the precrack tips of loaded specimens are evidently responsible for the increased toughness of these blends. The former two phenomena are attributed to the presence of spherulites while the plastic deformation of the methacrylate matrix is ascribed to cavitation of the polyurethane elastomeric phases in response to loading.     

Effect of environmental daily temperature fluctuations over one year storage on the prediction of non-enzymatic browning in reduced-moisture foods stored at “ambient” temperature

Non-enzymatic browning predictions in reduced-moisture foods stored over one year at “ambient” temperature, were made using, (a) realistic environmental daily (and seasonal) temperature fluctuations, and (b) a constant mean temperature. Daily temperature records taken every 6 h from January 1st to December 31st (1460 temperature data) in four selected cities from Argentina, were used.

The predicted amount of browning over one year storage was different depending whether the annual mean temperature (T_am), the monthly mean temperature (T_mm) or the daily temperature fluctuations (T_df) were used for the predictions. Predicted browning over one year was generally higher when realistic storage conditions (i.e., daily/seasonal temperature fluctuations) rather than mean values (annual or monthly), were used instead.     

The Impact of Order Incongruence Between a Task-Irrelevant Auditory Sequence and a Task-Relevant Visual Sequence.

A novel effect is reported in which serial recall of visual digits was disrupted to a greater degree by the presence of the same set of digits presented as an irrelevant auditory sequence than by the presence of irrelevant auditory consonants, but only when the order of the irrelevant digits was incongruent with that of the to-be-remembered digits (Experiment 1). Experiment 2 replicated this order-incongruence effect and showed also that disruption was dictated by the number of order-incongruent transitions but not by the number of novel tokens contained within the irrelevant sequence. The results favor an interference-by- process approach to the disruption of serial memory by irrelevant sound over approaches based on notions of interference by content and/or interference by depletion of attentional resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

美国是如何运用法律手段维护市场竞争秩序的

美国为保持市场经济特征,制定了世界第一个成文的公平交易法,以后又相继制定了一系列法令,以法规范市场竞争行为,保护竞争的实践,完善自由市场的竞争运转。     

Order relation between intervals and its application to shortest path problem

It is true that intervals are frequently partially ordered and cannot be compared. Nevertheless, varous definitions for ranking intervals have been proposed. In this paper, we propose a new definition for order relation between intervals by introducing a parameter called “a degree between partial and total order”, and apply it to the shortest path problem with arcs represented as intervals. In order to solve this problem, we modify the Dijkstra's algorithm, and propose a new algorithm obtaining some incomparable interval solutions. Finally, a numerical example is shown.     

利用双通道格形滤波器同时辨识ARMA模型的参数和阶次

本文重新构造了一种最小二乘通道格形滤波器，并将它用于同时辨识ＡＲＭＡ模型的参数和阶次。数值仿真结果表明，这种辨识算法具有计算量小、精度高等优点。     

Synthesis characterization of magnetic properties in La0.7−x Lnx Pb0.3 MnO3 (, Nd, Gd, Dy, Sm and Y) perovskite compounds

The influence of La substitution by rare-earth elements on the magnetization behaviors of perovskite oxides, La_0.7−x Ln_x Pb_0.3 MnO₃ (Ln=Pr, Nd, Gd, Dy, Sm and Y), is investigated. The replacement of La ion by Pr, Nd, Gd, Dy, Sm or Y results in a considerable decrease in the ferromagnetic ordering temperature T_C and clearly irreversible behavior in the FC–ZFC curves showing a short-range spin order phase. The fact is in agreement with the smaller ionic radii of Pr, Nd, Gd, Dy, Sm and Y ions in contrast to La ion and the corresponding larger distortion of perovskite structures. The saturation magnetization M_S increases as Pr or Nd content increases while M_S decreases as Sm or Y content increases. Moreover, the saturation magnetization M_S increases and then decreases as Gd or Dy content increases. These results can be explained in terms of the competition between the increase of ferromagnetically interacting spins due to the introduction of magnetic ions with f-shell electrons and suppression of ferromagnetism due to structure tuning induced by the small ionic radius of the interpolated cation into the La-site.     

厄米-高斯型短脉冲在光纤中传输的理论研究

从含高阶色散的非线性薛定谔方程出发 ,用矩法研究了厄米 高斯型短脉冲在光纤中的传输 ,获得了脉冲各参量在光纤中演化的耦合微分方程组 ,再利用龙格 库塔法得到此微分方程组的解 ,并与数值模拟进行了比较 ,两者吻合较好。     

Investigation of ordering and disordering in B-doped Ni76Al24 by residual resistometry

Homogeneous long-range ordering (LRO) kinetics in Ni₇₆Al₂₄ + 0.19 at.% B was studied by residual resistometry. The LRO relaxations were composed of two simultaneous processes showing dramatically different rates strongly dependent on temperature. The resulting very high activation energy of the processes was in agreement with previous results indicating its correlation with the value of the “order-disorder” transition temperature. The results were compared with the literature data and discussed in terms of the microscopic image of vacancy migration in the L1₂ superstructure.     

割线法向牛顿法的过渡格式

构造了不用导数值接近２阶收敛速度的非线性方程求根公式，敛速与牛顿法不分上下，但比牛顿法放宽了初值的选择。