Effect of stearic acid, zinc stearate coating on the properties of synthetic hydromagnesite

Synthetic hydromagnesite (SHM), used as flame retardant for polymers, may have similar or better flame retardancy effectiveness than aluminum tri-hydroxide (ATH) and magnesium di-hydroxide (MDH). Suitable surface modifiers are often employed to improve its dispersion and compatibility with polymer matrix. In this study, we chose stearic acid (SA) and zinc stearate (ZS) as the surface modifier, and investigated the properties of SHM modified with various surface modifier content using dry blending coating process. Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), particle size distribution, contact angle, oil absorption, bulk density, tapped density and Carr's index were employed to characterize the effect of surface modification. The results showed that the surface of SHM powders was changed from hydrophilic to lipophilic. The flowability of the surface modified powder was also improved. TG graphs showed that the surface modifier had no obvious influence on the degradation pathway of the SHM.     

例谈如何提高高考物理选择题的得分效率——对2010年浙江理科综合物理选择题的分析与理解

选择题历来是高考试题中的重要组成部分.2010年高考浙江省理科综合试卷中物理选择题分为两类,单项选择和不定项选择,每题均为6分,共7题,所占分值为42分.选择题的特点是小巧,考查信息量大,内容具体,知识点覆盖面广.命题人员可以根据试卷的整体意图设置选项,对考生进行有目的的干扰;但无法侧重考查出考生的思维过程和表达     

ICP-AES法检测芍药对矿质元素的吸收利用

为了分析芍药对土壤矿质元素的吸收利用规律,采用ICP-AES法检测了不同产地芍药根和相应土壤中K,Ca,Na,Mg,Fe,Cu等主要矿质元素含量.结果表明:不同产地的芍药对土壤中矿质元素的吸收利用效率不同,反映在不同产地的芍药根中有些矿质元素含量有明显差异,从而使各地芍药药材质量在矿质元素方面也有差异,以黑龙江和内蒙古...     

Existence of solutions for a damped nonlinear impulsive problem with Dirichlet boundary conditions

In this paper, we consider the existence of solutions for second‐order nonlinear damped impulsive differential equations with Dirichlet boundary condition. By critical point theory, we obtain some existence theorems of solutions for the nonlinear problem. We extend and improve some recent results. Copyright © 2013 John Wiley & Sons, Ltd.     

Plancherel–Rotach Asymptotic Expansion for Some Polynomials from Indeterminate Moment Problems

We study the Plancherel–Rotach asymptotics of four families of orthogonal polynomials: the Chen–Ismail polynomials, the Berg–Letessier–Valent polynomials, and the Conrad–Flajolet polynomials I and II. All these polynomials arise in indeterminate moment problems, and three of them are birth and death process polynomials with cubic or quartic rates. We employ a difference equation asymptotic technique due to Z. Wang and R. Wong. Our analysis leads to a conjecture about large degree behavior of polynomials orthogonal with respect to solutions of indeterminate moment problems.     

Packing and Covering with Centrally Symmetric Convex Disks

Given a convex disk K (a convex compact planar set with nonempty interior), let δ _L (K) and θ _L (K) denote the lattice packing density and the lattice covering density of K, respectively. We prove that for every centrally-symmetric convex disk K we have that $$ 1\le\delta_L(K)\theta_L(K)\le1.17225\ldots $$ The left inequality is tight and it improves a 10-year old result.     

An intelligent decomposition of pairwise comparison matrices for large-scale decisions

A Pairwise Comparison Matrix (PCM) has been used to compute for relative priorities of elements and are integral components in widely applied decision making tools: the Analytic Hierarchy Process (AHP) and its generalized form, the Analytic Network Process (ANP). However, PCMs suffer from several issues limiting their applications to large-scale decision problems. These limitations can be attributed to the curse of dimensionality, that is, a large number of pairwise comparisons need to be elicited from a decision maker. This issue results to inconsistent preferences due to the limited cognitive powers of decision makers. To address these limitations, this research proposes a PCM decomposition methodology that reduces the elicited pairwise comparisons. A binary integer program is proposed to intelligently decompose a PCM into several smaller subsets using interdependence scores among elements. Since the subsets are disjoint, the most independent pivot element is identified to connect all subsets to derive the global weights of the elements from the original PCM. As a result, the number of pairwise comparison is reduced and consistency is of the comparisons is improved. The proposed decomposition methodology is applied to both AHP and ANP to demonstrate its advantages.     

The classification of golden shaped hypersurfaces in Lorentz space forms

In this paper, we will study the golden shaped hypersurfaces in Lorentz space forms. Based on the classification of isoparametric hypersurfaces, we obtain the whole families of the golden shaped hypersurfaces in Minkowski space, de Sitter space and anti-de Sitter space, respectively.     

Boundary of Anosov dynamics and evolution equations for surfaces

We show that a compact surface of genus greater than one, without focal points and a finite number of bubbles (“good” shaped regions of positive curvature) is in the closure of Anosov metrics. Compact surfaces of nonpositive curvature and genus greater than one are in the closure of Anosov metrics, by Hamilton's work about the Ricci flow. We generalize this fact to the above surfaces without focal points admitting regions of positive curvature using a “magnetic” version of the Ricci flow, the so‐called Ricci Yang‐Mills flow.