Ionenstrahlätzen – Verfahren und Ausrüstungen für die Mikrostrukturierung

Ion beam techniques are widely used jur modification as well us analysis of materials in development and production of VLSI circuits and their importance is continuously increased in course of the reduction of structure dimensions. Some possibilities and problems connected with the application of ion beams of low energy in the pattern transfer are- described and the stage of development achieved in the Central Institute of Isotope and Radiation Research is outlined.     

Radioimmunologische Bestimmung von Pflanzenhormonen

In vorliegender Arbeit wird eine kurze Darstellung der Grundlagen, Erfordernisse, Vor- und Nachteile des Radioimmunoassay für Pflanzenhormone gegeben.

The purpose of this paper is to discuss briefly the basis, requirements, advantages, and disadvantages of radioimmunoassay with respect to plant hormones.     

Isotope Effects in the Electrochemical Reduction of Oxalic Acid-D2 and Benzoic Acid-D

Abstract

The electrochemical reduction of model carboxylic acid at lead cathodes in deuterated media was studied for potential use in the synthesis of special deuterated compounds.

Oxalic acid-d₂ in D₂O gives good yields of glyoxylic acid-d₂. An unexpected large isotope effect of 5.3 ± 1.7 was found in this reaction, leading to significant depletion of deuterium content in the aldehyde group.

Benzoic acid-d in CD₃OD/diluted D₂SO₄ yields benzyl alcohol-d, 7,7-d₂. The isotope effect of 2.4 ± 1.0 is within the expected range. No deuterium is incorporated into the aromatic nucleus. Essentially unlabelled benzyl alcohol is obtained in CD₃OH/dil. H₂SO₄.     

Ab initio calculation of phonons in bulk HfC and the HfC(001)(1 × 1) surface

Structural, elastic and dynamical properties of the rock-salt HfC have been studied by employing an ab initio pseudopotential method and a linear response scheme, within the generalised gradient approximation. In addition to achieving good agreement with experimental measurements of the phonon dispersion results along the symmetry direction Γ-X, we have presented accurate dispersion results along several other directions in the Brillouin zone. Sharp features in the phonon density of states are ascertained and their origin discussed. This is followed by investigations of the structural, electronic and phonon properties of the HfC(001) surface. The agreement between our surface phonon spectrum and experimental measurements is very good. By analysing the atomic displacement patterns of the zone-centre and zone-edge phonon modes we have determined the energy locations and polarisation characteristics of Fuchs–Kliewer, Wallis, Lucas and Rayleigh modes.     

Helical twisting power of antiferroelectric chiral terphenyls in different matrices

To determine the influence of chemical structure on the Helical Twisting Power (HTP), we tested four optically active dopants having a terphenyl rigid core and the same chiral centre but differing in the length of nonchiral terminal chain and the substitution of benzene rings with fluorine atoms. The compounds were added to different achiral liquid crystalline matrices: nematic and smectic C. It was found that HTP as well as its temperature variation depends on the kind of used matrices. It gives a conclusion that information about HTP obtained in one matrix cannot be uncritically transferred to another one.     

Phase transformations and structural characteristics of AL–Cu–Co(–Si) decagonal phase

The phase transformations and structural characteristics of the Al-Cu-Co-Si alloy have been studied by neutron diffraction and high-resolution electron microscopy. The Al₆₅Cu_17.5Co_17.5 decagonal phase is stable in the temperature range between 973 K and 1350 K. At the low-temperature end, it relaxes to a microcrystalline approximant structure. At the high-temperature end, it melts directly into liquid. Two distinct orthorhombic phases are identified in the Al₆₃Cu_17.5Co_17.5Si₂ microcrystalline structure. They are composed of several structure units that can also construct the Penrose tiling. Because of lack of units, a single orthorhombic phase cannot undergo the transformation towards the high-temperature decagonal phase. An analysis of the orientation relationships between the CsCl and orthorhombic phases leads to the definition of Penrose tiling-like subnetworks inside the orthorhombic unit cells so that these orthorhombic phases can be regarded as the periodic patchworks of quasiperiodic subnetworks.     

Study on the Reinforcing Effect of Milled Carbon Fibers in a Natural Rubber Based Composite

Milled carbon fibers (MCF) have been tested at 2, 4, and 6 phr in a standard natural rubber compound with 45 phr of N375 carbon black. A dramatic increase in the low elongation moduli was observed even with only 2 phr of MCF. The presence of MCF confers anisotropic properties to the rubber compounds that can be measured by an anisotropic factor σ, defined as the ratio between the modulus parallel to the MCF prevalent direction over the modulus orthogonal to the MCF prevalent direction. It has been shown that the presence of MCF is able to reduce the mechanical hysteresis and also the compression set of the natural rubber compound. However, the tear strength properties are affected negatively. The present study demonstrates the feasibility and the advantages derived by the utilization of the carbon fibers as extra reinforcing filler in rubber compounds.     

洗涤剂中含磷化合物的31PNMR快速检测方法

收集了常见的31种含磷无机化合物和84种含磷有机化合物,首次建立了含磷化合物的核磁共振谱图库,并以此为依据建立了31P NMR技术快速检测洗涤剂中含磷化合物的方法.对洗衣粉、金属清洗剂和除油剂样品进行31P NMR分析,经与31P谱图库比对,可快速确定含磷化合物的结构.结果表明,10种洗衣粉中仅有1种检出含磷化合物,其...     

通过超宽139La固体核磁共振波谱研究层状La(OH)2NO3

层状稀土氢氧化物是一类新型的稀土功能材料,本文采用固体核磁共振（SSNMR）方法研究了同时具备离子交换能力和非线性光学特性的层状La（OH）₂NO₃化合物,探讨了通过四极核CPMG（QCPMG）脉冲序列和变频谱图采集获取超宽¹³⁹La SSNMR谱图的方法,并描述了适用于此类实验的滤波方程和谱图重建方法.重建谱图同时包含四极核中心跃迁和卫星跃迁信息,本文使用QUEST软件对超宽¹³⁹La NMR谱图进行了模拟,获取的四极耦合常数C_Q和非对称因子η_Q均与CASTEP密度泛函理论计算值高度吻合.SSNMR实验结果证实层状La（OH）₂NO₃化合物属于非中心对称结构（P2₁）,解决了对其结构长期以来存在的争论.