Dynamic measurements on polymer solutions and melts

Summary An apparatus for the measurement of the dynamic viscosity is described. In a coaxial cylinder geometry forced vibrations are executed in the frequency region from 2·10^–4 to 50 cycles/sec. Fluids with a wide range of viscosities (10^–1 to 10⁷ poise) can be measured. A number of experimental results obtained on dilute solutions and melts of polymers are given and compared with results of the molecular theories.

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Zusammenfassung Es wird ein Gerät für die Messung der dynamischen Viskosität beschrieben. Innerhalb eines koaxialen Zylindersystems werden im Frequenzgebiet von 2 · 10^–4 bis 50 Hz erzwungene Schwingungen ausgeführt. Messungen an Flüssigkeiten sind in einem weiten Viskositätsbereich (10^–1 bis 10⁷ Poise) möglich. Einige Messungen an verdünnten Lösungen oder Schmelzen von Hochpolymeren werden mitgeteilt und mit Voraussagen molekularer Theorien verglichen.

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Paper read at the Annual Meeting of the German Rheologits, Berlin-Dahlem, May 20–21, 1968).     

三维光存储中折射率失配引起的球差补偿

为实现三维光存储中折射率失配引起的球差补偿,建立了光学存储系统模型,获得了折射率失配引起的波前偏差函数与存储深度的表达式.采用泽尔尼克循环多项式对波前偏差函数进行补偿展开.在双光子荧光和单光子共焦荧光读出方式下,均可获得读出荧光强度与存储深度的关系:在折射率失配引起的球差未得到补偿矫正的情况下,存储深度在200 μm左右读出荧光强度基本上下降为零;当折射率失配引起的初级球差被补偿矫正后,读出荧光强度随存储深度的下降得到较好改善;当折射率失配引起的二级球差被补偿矫正后,存储深度在1 mm内存储点强度随深度基本上没有明显地变化.并且对像差补偿方法进行了具体地分析.     

类氖钛X射线激光实验研究

在“星光”装置上采用预脉冲技术和透-反射线聚焦系统成功地进行了类氛钛x射线激光实验.测量了TiXⅢ,3s-3p,J=0～1激光线的增益系数.首次实验研究了预脉冲能量不同时,激光线强度随泵浦激光能量的变化及其发散角和偏转角.     

On the limiting profile arising from orthonormalizing shifts of exponentially decaying functions

It is shown that, under certain conditions, orthonormalizingthe positive integer shifts of an exponentially decaying functionon the half line by the Gram-Schmidt process leads to a limitingprofile given by orthonormalizing all their integer shifts onthe whole line. These results derive from properties of Choleskyfactorization of bi-infinite and semi-infinite matrices. Anexample is provided by the negative exponential function andconjectures are given, supported by numerical evidence, forthe Gaussian and Lorentz function.     

On the singularity of Green's tensor for a perfectly conducting semi-infinite cone

This paper is intended to clarify a misunderstanding concerningthe source singularity of the electric Green's tensor for aperfectly conducting semi-infinite cone of circular cross-section.Tai's series expansion of the Green's tensor is known to lacka singular term at the source region. Jones has reconstructedthe solution to this problem and has pointed out the differencebetween his result and that of Tai. The aim of our paper isto demonstrate that, although Jones's closed-form solution iscorrect, there is a mistake in his comparison with Tai's seriessolution. We conclude that one of the two additional singularterms that Jones claims as missing from Tai's formula must beomitted. Besides, we compare Jones's closed-form solution withSmyshlyaev's solution to the very same problem. We concludethat the magnetic field expressions given by Jones and Smyshlyaevcoincide, but a singular term is missing from Smyshlyaev's expressionfor the electric field.     

太阳风等离子体输出流量的全日面二维结构

本文根据1983年十个 Carrington 周(1733—1742)期间的 K-日冕亮度、行星际闪烁(IPS)观测和光球磁场观测,首次探讨了太阳风等离子体质量、动量和能量输出流量 F_M,F_P 和 F_E 的全日面二维平均结构及其与光球磁场结构的关系.     

Copper(II) chloride complexes with multimodal ligands based on the cyclotriphosphazene platform

The reaction of hexakis(2-pyridyloxy)cyclotriphosphazene (L) and hexakis(4-methyl-2-pyridyloxy)cyclotriphosphazene (MeL) with copper(ii) chloride afford the complexes [CuLCl(2)], [(CuCl(2))(2)(MeL)], [CuLCl]PF(6) and [Cu(MeL)Cl]PF(6). The single-crystal X-ray structure of [CuLCl(2)] shows the copper ion to be in a square based pyramidal distorted trigonal bipyramidal (SBPDTBP) environment (tau= 0.47) with L acting as a kappa(3)N donor, coordinating via the nitrogen atoms from two non-geminal pyridyloxy pendant arms, a nitrogen atom in the phosphazene ring and two chloride ions. In the dimetallic complex, [(CuCl(2))(2)(MeL)], the geometry about both (symmetry related) copper(ii) centres is also SBPDTBP (tau= 0.57) with a 'N(3)Cl(2)' donor set. In the monocation of [CuLCl]PF(6), L acts as a kappa(5)N donor, bonding to the copper(ii) centre through the nitrogen atoms of four pyridyloxy pendant arms, a phosphazene ring nitrogen atom and a chloride ion to give an elongated rhombic octahedral coordination sphere. The phosphazene ring atoms remain virtually coplanar in all three structures as a consequence of the phenoxy-hinge, which links the pyridine pendant donors to the cyclotriphosphazene platform, allowing the formation of six-membered chelate rings. The spectroscopic (mass spectral, EPR and electronic) and magnetic properties of the complexes are discussed. The EPR and variable temperature magnetic susceptibility results for the dicopper complex, [(CuCl(2))(2)(MeL)], point to a very weak electronic interaction between the metal atoms.     

Aggregation induced colour change for phosphorescent iridium(III) complex-based anionic surfactants

We describe a new class of water soluble metallosurfactant molecules based on luminescent neutral iridium(III) complexes. The compounds possess an alkyl chain terminated with a negatively charged group, a sulphate. Due to their amphiphilic nature they assemble in aggregates in water and their photophysical properties, as well as the morphological characterization of the assemblies are presented. In particular, UV-Vis absorption, steady-state and time-resolved emission spectroscopy, dynamic light scattering and scanning electron microscopy techniques have been employed towards the analysis of the assemblies in different media. Comparison with the single components shows that the aggregates have very different photophysical properties. Importantly, the change in colour upon self-assembly is a remarkable feature which could be used for the design of probes which can change properties in different environments.     

The synthesis of 6,6′-cyclo-6′-deoxyhexofuranosyluracils via a diazomethane-promoted ring-enlargement reaction

The protected 5′-oxo-6,5′-cyclouridine 13 reacts with diazomethane to afford mostly the spiro-epoxide 18 (79%), but it also undergoes ring-expansion to give the corresponding 5′-oxo-6,6′-cyclonucleoside 16. Under the conditions of the reaction, ketone 16 reacts further with diazomethane to give the enol ether 20 (12% overall), the isomeric 4-methoxy nucleoside 15 (2%), and the spiro-epoxide 19 (4.4%). Acid hydrolysis of the enol ether 20 , followed by reduction of the resulting ketone with sodium borohydride, affords a separable mixture of the 5′S (L-talo) and 5′R (D-allo) methylene-bridged cyclonucleosides 7 and 8 , respectively. From proton nmr measurements, it appears that the 6′-methylene groups of these cyclonucleosides project towards the 2′,3′-edge of the furanose ring.