Mixed convection unsteady stagnation point flow over a stretching sheet with heat transfer in the presence of variable free stream

An analysis is performed for the unsteady mixed convection flow of an incompressible viscous fluid about a stagnation point on a stretching sheet in the presence of a variable free stream. The equations of motion and energy are transformed into the ordinary differential equations by using similarity transformations. Homotopy analysis method is used for the solution of the governing problem. The results have been discussed by plots. The present values of the function are shown very close to the previous limiting solutions. Copyright © 2011 John Wiley & Sons, Ltd.     

Rational points and Galois points for a plane curve over a finite field

We study the relationship between rational points and Galois points for a plane curve over a finite field. It is known that the set of Galois points coincides with that of rational points of the projective plane if the curve is the Hermitian, Klein quartic or Ballico–Hefez curve. The author proposes a problem: Does the converse hold true? If the curve of genus zero or one has a rational point, we have an affirmative answer.     

Index transforms with Weber-type kernels

New index transforms with Weber-type kernels, consisting of products of Bessel functions of the first and second kind, are investigated. Mapping properties and inversion formulas are established for these transforms in Lebesgue spaces. The results are applied to solve a boundary value problem on the wedge for a fourth-order partial differential equation.     

Simultaneous quantitation of rosuvastatin and ezetimibe in human plasma by LC–MS/MS: Pharmacokinetic study of fixed‐dose formulation and separate tablets

A simple, high‐throughput and highly sensitive liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) method has been developed for the simultaneous estimation of rosuvastatin and free ezetimibe. Liquid–liquid extraction was carried out using methyl‐tert butyl ether after prior acidification from 300 μL human plasma. The recovery for both the analytes and their deuterated internal standards (ISs) ranged from 95.7 to 99.8%. Rosuvastatin and ezetimibe were separated on Symmetry C₁₈ column using acetonitrile and ammonium formate buffer, pH 3.5 (30:70, v/v) as the mobile phase. The analytes were well resolved with a resolution factor of 3.8. Detection and quantitation were performed under multiple reaction monitoring using ESI(+) for rosuvastatin (m/z 482.0 → 258.1) and ESI(−) for ezetimibe (m/z 407.9 → 271.1). A linear response function was established in the concentration ranges of 0.05–50.0 ng/mL and 0.01–10.0 ng/mL for rosuvastatin and ezetimibe, respectively, with correlation coefficient, r² ≥ 0.9991. The IS‐normalized matrix factors for the analytes ranged from 0.963 to 1.023. The developed method was successfully used to compare the pharmacokinetics of a fixed‐dose combination tablet of rosuvastatin‐ezetimibe and co‐administered rosuvastatin and ezetimibe as separate tablets to 24 healthy subjects. The reliability of the assay was also assessed by reanalysis of 115 subject samples.     

我国渔业企业经济效益分析研究——以2013年我国上市渔业公司数据为例

随着居民收入水平的提高,我国水产品消费数量不断增加.水产品消费需求的增加,一方面导致水产品养殖企业数量增多,水产品养殖产业初具规模;另一方面也导致了市场竞争压力的增大,使得水产品养殖企业经济效益降低.利用2013年我国上市渔业公司财务数据,基于因子分析法研究了我国上市渔业公司经济效益水平.研究结果显示,2013年大湖股份、国联水产各公共因子及综合因子得分都较高,表明其公司盈利能力、偿债能力及运营能力较强,企业后期发展前景较好.而好当家、武昌鱼的综合因子得分较低,需要引起公司重视.最后针对2013年我国上市渔业公司的整体得分情况,提出了提高我国渔业企业经济效益水平的建议.     

促进学科核心素养发展的不同实施模式的主题教学研究——以“氮循环”主题为例

主题教学因其整合性和问题解决的情境能够实现促进学科核心素养的发展,促进学科核心素养发展的主题教学呈现出3种不同开放度的实施模式:常态教学中开放度小、常态教学中开放度大、翻转课堂的主题教学实施模式。为了探索3种实施模式的教学效果,挖掘教学中的关键问题与对策,以“氮循环”主题教学为例,在3个实验班开展实证研究。研究结果表明,3种实施模式均实现了促进学生学科核心素养的发展,但对促进学科核心素养的不同维度效果不同。3种实施模式都存在实现学科核心素养的发展进阶、学生的情感发展过程、建立评价体系、教师有效干预等方面的关键问题,此外每种实施模式也有其特有的关键问题,本研究依据教学实践给出了积极建议和对策。     

与 Cauchy 微分中值定理相关的几个问题

根据Cauchy微分中值定理表达式的结构引入辅助函数 F（x ，c）＝ f （x）- f （c）g（x）- g（c）（a＜ c＜ b），通过讨论其可导性，得到相关的几个不等式，由此得出Cauchy微分中值定理存在唯一“中值点”的一个条件，并给出其逆定理的一个较弱表述。     

Oscillation theorems for symplectic difference systems

We consider symplectic difference systems involving a spectral parameter, together with the Dirichlet boundary conditions. The main result of the paper is a discrete version of the so-called oscillation theorem which relates the number of finite eigenvalues less than a given number to the number of focal points of the principal solution of the symplectic system. In two recent papers the same problem was treated and an essential ingredient was to establish the concept of the multiplicity of a focal point. But there was still a rather restrictive condition needed, which is eliminated here by using the concept of finite eigenvalues (or zeros) from the theory of matrix pencils.     

Continuous dependence on data for bilocal difference equations

The continuous dependence on data is studied for a class of second order difference equations governed by a maximal monotone operator A in a Hilbert space. A nonhomogeneous term f appears in the equation and some bilocal boundary conditions a, b are added. One shows that the function which associates to {a, b, A, f} the solution of this boundary value problem is continuous in a specific sense. One uses the convergence of a sequence of operators in the sense of the resolvent. The problem studied here is the discrete variant of a problem from the continuous case.     

Synthesis and Characterization of Novel Biodegradable Di‐ and Tri‐Block Copolymers Based on Ethylene Carbonate Polymer as Hydrophobic Segment

Synthesis of novel amphiphilic biodegradable block copolymers based on ethylene carbonate is reported in this study. Polyethylene glycol monomethyl ether (MeO‐PEO) and polyethylene glycol (PEG) of varying molar masses are used as macro‐initiator for ring‐opening polymerization of ethylene carbonate in the presence of sodium stannate trihydrate as a heterogeneous transesterification catalyst. Earlier elution of block copolymer from macro‐initiator in size exclusion chromatography (SEC) indicated the successful synthesis of the block copolymers. Ratios of both types of blocks are varied systematically. Liquid chromatography at critical conditions is used for the analysis of the non‐critical individual blocks, and if there are any critical segments that are not attached to the non‐critical block. To the best of our knowledge, this is the first report on the synthesis of ethylene carbonate‐based amphiphilic block copolymers. Chromatographic critical conditions of the ethylene carbonate polymer are also reported for the first time. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1887–1893