The influence of side branches on the structure of crystalline phase in ethylene-1-alkene copolymers

The influence of side branches on the unit cell dimensions in ethylene-1-alkene copolymers was investigated both at room temperature as well as during heating of the samples up to melting. Time resolved X-ray diffraction investigations revealed that in the case of ethylene-1-octene copolymers with low and moderate comonomer content, the transversal expansion of the unit cell occurs due to the limited thickness of lamellae, however the samples with higher comonomer content (above 5 mol %) exhibit distinctly larger expansion resulting from the stresses imparted on the basal surfaces of crystals by the excluded branches. At high temperatures, independently on the thermal expansion, an additional increase of the unit cell volume occurs, caused probably by a penetration of the end-parts of side branches, residing near the crystals surface, into the surface cells. Similar phenomenon is observed for ethylene-1-butene copolymer. On contrary, the ratio of the average unit cell volume in ethylene-1-propene copolymer to the unit cell volume in linear polyethylene at the same temperature, decreases starting from about 50 °C. Such a behavior is a new confirmation of a partial inclusion of methyl branches into the crystalline phase. Most probably, when the temperature increases, the volume of included branch becomes a decreasing fraction of the thermally expanding unit cell volume.     

Phase equilibria in the CdI2-Ag2Se system

The phase diagram of the system CdI₂-Ag₂Se is studied by means of X-ray diffraction, differential thermal analysis and measurements of the density of the material. The unit cell parameters of the intermediate phase 2CdI₂·3Ag₂Se were determined a = 0.6387 Å, b = 4.311 Å, c = 4.044 Å; α = 113.72°, β = 90.27° and γ = 94.85°. The intermediate phase 2CdI₂·3Ag₂Se has a polymorphic transition at 125 °C. It melts incongruently at 660 °C.     

The Crystal and Electronic Structure of A Reticular Type Mo-Fe-S Cluster Compound [Et_4N]_4[Mo2Fe_4S_9(SCH_2CH_2S)_2]

The single crystal of [Et4N]4 [MO2Fe4S9(SCH2CH2S)2] was obtainedby reaction of (NH4)2HoS4, FeCl3 , HSCH2CH2SH and Et4 NBr in CH3CN and MeOH-MeONa. Cluster compound [Et4N]4 [Mo2Fe4S9(SCH2CH2S)2] crystal -Lized in the monoclinic space group C2/c with unit cell parameters:a = 17. 672(2)A, b = 33. 851(4)A, c = l3. 900(3)A, β=135.11(4)°, V=5868.8 (3.9)A3 and Z = 4. On the basis of 3514 unique data (I>2σ(I)) the structure was refined to R = 0.0575. The anion [Mo2Fe4S9(SCH2CH2S)2]4-of the cluster compound includes doubly bridging (μ2-S), triply bridging (μ3-S) and quadruply bridging (μ4 -S) . The structrue analysis gives a rule with bond lengths decreasing in the order of Fe-(μ4-S)> Fe-(μ3-s)> Fe-(μ2 -s) and EHMO calculation gives the other rule with bond order increasing in the order of Fe-(μ4-S)< Fe-(μ3-S)相似文献   

单位圆内亚纯函数的Nevanlinna不等式和相关的奇异半径

应用Ahlfors覆盖曲面的方法,得到几个单位圆内亚纯函数的Nevanlinna基本不等式,应用它们证明了亚纯函数在单位圆内关于小函数的奇异半径的存在性,推广了复平面上亚纯函数奇异方向的相关结论.     

C~n中单位球面上的不变g-函数及BMOA

设B是C~n中的单位球,S是C~n中的单位球面。■(f)是定义在S上的不变g-函数．设f∈ BMOA,若存在正测度集ES,使■(f)＜ ∞在E上成立,则■(f)＜ ∞在S上几乎处处成立,同时■(f)∈BMO(S)且存在常数C,使得‖■(f)‖≤C‖f‖.     

Cesàro operators on Hardy spaces in the unit ball

This article establishes the boundedness of the generalized Cesàro operator on holomorphic Hardy spaces in the unit ball. The approach consists in writing the generalized Cesàro operator as a composition of certain integral operators.     

A lower regulator bound for number fields

Lower bounds for regulators of algebraic number fields are very important for a variety of applications. Good estimates depend at least on the degree and the discriminant of the considered field. In this paper we present an improved bound which is obtained from more specific field data, e.g. the size of small T₂-values of the integers of the field. This is of considerable interest for computations in practice, for example, of fundamental units.     

Subduction of coset representations

Summary Enumerations of compounds based on a parent skeleton with and without the influence of obligatory minimum valency (OMV) are reported. The effect of the OMV is formulated by assigning different weights to the respective orbits of the parent skeleton. This type of enumeration requires introduction of several new concepts that are derived from the subduction of coset representations, e.g., a unit subduced cycle index, a subduced cycle index and the number of suborbits.     

p-Bloch空间上的复合算子和加权复合算子

本文系统地讨论了单位圆中p-Bloch空间上复合算子T1,δ的有界性和紧性以及加权复合算子Tφ,δ的有界性,同时也在小p-Bloch空间上讨论了复合算子T1,φ的有界性问题.主要得到以下结论: (i)Tφ,δ是空间βp到βq的有界算子之充要条件; (ii)T1,φ是空间βp到βq的紧算子之充要条件; (iii)T1,φ是空间βp0到βq0的有界算子之充要条件等.从空间或算子上扩展了文[1,4]的相应结论.     

光杠杆底脚、望远镜轴线不水平造成的系统误差的分析

本对拉伸法测金属弹性模量实验中光杠杆底脚水平、望远镜轴线不水平而造成的系统误差进行了定量分析，所得出的结论，不仅对本实验适用，并且对其它应用光杠杆镜尺组的同类实验也适用。