An Empirical Approach for Estimating the Density of Multicomponent Aqueous Solutions Obeying the Linear Isopiestic Relation

An empirical approach is presented for the density of aqueous multicomponentsolutions conforming to the linear isopiestic relation. This approach can be usedto estimate the densities of multicomponent systems from data on the constituentbinary subsystems at the same water activity. Predicted and measured densitiesfor 22 mixtures have been compared, using the simple Young's rule, theisopycnotic mixing rule of Teng and Lenzi, and the present method. The present methodand Young's rule give the most accurate predictions for strong electrolyte mixtureswithout common ions and for the mixtures with strong ion complexes, respectively.There is no universal best method for the strong electrolyte mixtures with commonions. An extensive comparison has also been given between apparent molarvolume predictions by Young's rule and by the new method. The two rules arerelatively better for the strong electrolyte mixtures without common ions andmixtures containing the transition metal chlorides, respectively. However, neitheris universally better for mixtures of strong common-ion electrolytes.     

Torsional impact response of a penny-shaped crack in a functional graded strip

The torsional impact response of a penny-shaped crack in a nonhomogeneous strip is considered. The shear modulus is assumed to be functionally graded such that the mathematics is tractable. Laplace and Hankel transforms were used to reduce the problem to solving a Fredholm integral equation. The crack tip stress field is obtained by considering the asymptotic behavior of Bessel function. Explicit expressions of both the dynamic stress intensity factor and the energy density factor were derived. And it is shown that, as crack driving force, they are equivalent for the present crack problem. Investigated are the effects of material nonhomogeneity and strip‘s highness on the dynamic fracture behavior.Numerical results reveal that the peak of the dynamic stress intensity factor can be suppressed by increasing the nonhomogeneity parameter of the shear modulus, and that the dynamic behavior varies little with the adjusting of the strip‘ s highness.     

负压区的存在对刚性陶瓷过滤器脉冲反吹性能的影响

利用压电式压力传感器测定了陶瓷过滤器在脉冲反吹过程中滤管内动态压力的变化规律,表明在脉冲反吹快要结束和正常过滤尚未开始的过渡过程中,滤管内存在严重的负压区。利用单个颗粒轨道模型分析了部分已被吹离滤管表面的小颗粒在负压区的作用下会重新返回到滤管壁,从而证实了负压区是影响刚性陶瓷过滤器稳定运行的重要原因。     

On uniqueness, existence and objectivity of S-R decomposition theorem

I.IntroductionThedecompositionofadeformationgradientfunctionFisafundamentalproblemforfinitedeformationtheory.Greenstraintheoryandpolardecompositiontheorywereemployedbymostscientists,However,thesetheorieshaveallsomeconsiderabledrawbacks.Inl979,ChenZhidadev…     

ICP-OES法测定镍铬合金中Si，Mn，Fe，Ti，Al，Cu多种元素

建立了电感耦合等离子体发射光谱法测定镍铬合金中Si,Mn,Fe,Ti,Al,Cu元素含量的分析方法。确定了溶样方法和分析谱线,采用基体匹配消除干扰。对方法精密度和准确度进行实验,实验结果表明,各元素的相对标准偏差均小于3%,加标回收率在86.8%～106.9%,镍铬合金标准物质的各元素测定结果均与标准值一致。所建立的方法快速、准确,适用于镍铬合金中多元素同时测定。     

滴落状血迹形态的实验模拟研究

滴落状血迹是刑事案件现场常见血迹形态,是对犯罪现场重建分析的重要依据.本文通过血液滴落的模拟实验,分析测量结果,研究血液滴落的角度与高度对血迹形态的影响,并得出相应规律.通过对滴落状血迹形态的观察分析,反推血滴的出射角度,下落高度和排列的顺序,进而确定案发当时出血者的体位、姿势、朝向角度、动静关系.以期对现场重建有很大的帮助.     

Ionic Covalent Organic Framework: What Does the Unique Ionic Site Bring to Us?

Ionic covalent organic frameworks featuring both crystallinity and charged sites have arose tremendous attention from scientific community. The adjustable textural structures, well-defined channels and abundant charged sites of ionic COFs facilitate great potential in diverse aspects, such as separation, ion conduction, sensing, catalysis and energy storage. In this review, we first introduced the design and construction of ionic covalent organic frameworks(COFs), and classified them according to the types of charged sites. We focused on the various applications of ionic COFs in diverse fields. The structure-function relationship was also explored in detail. Finally, the opportunities and challenges of ionic COFs were summarized to provide guidance for better design and application of ionic COFs.     

In基二氧化碳氧化丙烷脱氢催化剂的研究

二氧化碳氧化丙烷脱氢增产丙烯是提高丙烷脱氢单程转化率与二氧化碳资源化利用的重要途经,探究高效的非贵金属环保型催化剂对工业界和科学界均有重要意义。采用不同合成方法制备了系列In基催化剂,通过X射线衍射、拉曼、H2-程序升温还原、扫描电镜观测了In活性位结构。关联活性数据得出,具有InO6结构的InOx团簇或In2O3颗粒在CO2氧化丙烷脱氢气氛中能够发生氧化还原循环,从而驱动CO2及丙烷分子的活化,而水热法合成样品中不含该InO6结构,因此不具备CO2活化能力。此外,十元环MFI型Silicalite-1沸石相比十二元环的Si-Beta沸石载体能够促进CO2的吸附,也提高了CO2对丙烷分子活化的促进作用。     

Mo助剂含量对Mo-Ni2P/SBA-15/堇青石整体式催化剂加氢脱硫性能的影响

 采用共浸渍法制备了 P/Ni 摩尔比为 2 的 Ni2P/SBA-15, 再通过二次浸渍引入助剂 Mo 制得 Mo-Ni2P/SBA-15, 将它调制成活性胶后均匀涂敷于预处理后的载体表面, 干燥焙烧后在氢气流中采用程序升温还原法, 制备了一系列 Mo-Ni2P/SBA-15/堇青石整体式催化剂. 采用 X 射线衍射、N2 吸附-脱附和 X 射线光电子能谱对催化剂结构进行了表征, 以二苯并噻吩为模型含硫化合物, 考察了催化剂的加氢脱硫性能. 结果表明, Mo 的加入增大了催化剂的比表面积, 在催化剂表面形成了 MoNiP2, 且 Ni2P 为主要活性物相. Mo 在催化剂表面主要以 Mo6+和 Moδ+形式存在; 当 w(Mo) = 4.2% 时, n(Mo)/n(Ni+Mo) = 0.18 的整体式催化剂上二苯并噻吩的转化率最高, 且在较低反应温度时以直接脱硫机理为主, 而较高反应温度时以加氢脱硫机理为主.     

The semi-ideal solution theory for mixed ionic solutions at solid-liquid-vapor equilibrium

The semi-ideal solution theory has been presented to describe the changes in thermodynamic properties accompanying the process of mixing the nonideal electrolyte solutions M(i)X(i)-(NY)sat-H2O (i = 1 and 2) at constant activities of NY and H2O, including concentration, chemical potential, activities of all M(i)X(i), Gibbs free energy, enthalpy, entropy, thermal properties, and volumetric properties. The theory states that, under the conditions of equal activities of NY and H2O, the average hydration numbers characterizing the ion-solvent interactions have the same values in the mixture as in the subsystems and the process of mixing these nonideal electrolyte solutions is as simple as that of mixing the ideal solutions if the contributions from the ion-ion interactions to the solvent activity are assumed to be the same in the mixture as in its subsystems, which has been justified by the calculations of the Pitzer equation. Therefore, a series of novel linear equations are established for the thermodynamic properties accompanying the process of mixing these nonideal solutions as well as mixing the ideal solutions M(i)X(i)-(NY)sat-H2O (i = 1 and 2) of equal mole fractions of NY and H2O. From these equations, the widely applied empirical Zdanovskii's rule is derived theoretically, and the important constant in the McKay-Perring equation under isopiestic equilibrium is determined theoretically, which has been substantiated by comparisons with the experimental results for 18 mixtures reported in the literature. Isopiestic measurements have been made for the systems BaCl2-LaCl3-H2O, NaCl-BaCl2-LaCl3-H2O, and NaCl-LaCl3-BaCl2.2H2O(sat)-H2O at 298.15 K. The results are used to test the novel linear concentration relations, and the agreement is excellent. The novel predictive equation for the activity coefficient of M(i)X(i) in M1X1-M2X2-(NY)sat-H2O has been compared with the calculations of the Pitzer equation, and the agreement is good.