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Studies on the workability of precise seeders by means of labelling methods has been possible due to the solution of the following problems: labelling of seeds, radiation collimation of labelled seeds being sown, elaboration of measuring and registering systems as well as processing systems of a measuring signal. The developed method allows for precise, quick and fully objective evaluation of the studied seeders to be done under natural conditions.     

Chirality-Dependent Resistivity in Carbon Nanotubes

Abstract

The phonon-mediated resistivity is calculated for metallic carbon nanotubes based on a continuum model for electrons and phonons. In armchair nanotubes, only twisting modes contribute to the resistivity, while both stretching and breathing modes are important in zigzag nanotubes. The resistivity shows chirality dependence at low temperatures where breathing modes are not populated but becomes independent of the chirality at high temperatures.     

New sorption and solvation measuring methods: Forced flow through liquids and solid state fluidised bed sorbents in high pressure gravimetry

A novel measuring method is presented here that allows sorption and solvation measurements near to different process conditions. Especially for the sorption kinetics it is important that the measuring conditions are similar to later applications. Particularly for high pressure sorption measurements this claim could not be fulfilled for most technical applications.The advantage of the measuring methods presented here is that solid bed samples in high pressure gravimetry can be measured under flow-through conditions in both directions and, for the first time in high pressure gravimetry, liquid samples can be measured under flow-through conditions. Especially for ionic liquids, of which a large variety of new substances with unknown sorption potentials have been synthesised in the last few years, this results in much shorter measuring times.The first measurements presented here show that the new system allows for measuring times around 26 times shorter for an ionic liquid.     

Rationelle Kalibrierung von Neutronensonden bei der radiometrischen Wassergehaltsbestimmung Anwendung unter Meßnetz- und Feldversuchshedingungen

Determinations of soil moisture witli the aid of neutron moisture meters require calibrations under real conditions. Some efficient methods for calibrating such moisture gauges are described and working examples are presented.     

Heavy alkali metal-arsenic alloy-based graphite intercalation compounds: Investigation of their synthesis and of their physical properties

Heavy alkali metal-arsenic alloys intercalate easily into graphite, leading to the formation of a new family of ternary graphite intercalation compounds (GICs). Pure phases formulated as MAsxC4s (M = K, Rb or Cs; s = stage; x ≤ 1) have been synthesized at the laboratory. This article aims to expose all physical measurements performed on these intercalation compounds to get an idea about their electronic properties.Electrical conductivity measurements have been performed both parallel and perpendicular to the basal planes, between 4.2 and 295 K. Room temperature resistivity values lie between 16 and 35 μΩ cm and the anisotropic resistivity takes a value of an order of magnitude of 10⁴. Dynamic magnetic susceptibility measurements, carried out at low temperature on some phases, showed that they do not exhibit superconducting transition up to 1.3 K. Raman spectroscopy investigation, which is a useful tool to study the electronic and the chemical stability of GICs, highlighted a significant up-shift of the G-band of the carbon intra-layer vibration frequency, compared to the pure graphite vibration mode. Undoubtedly, this is related to the electronic charge transfer established between graphite layers and intercalated species.     

An explanation for deviations from the quark number scaling of elliptic flows in low pT region

We carry out a systematic study of the different contributions to the deviations of the elliptic flows from the quark number scaling in high energy heavy ion collision in a quark combination model.The effects that we considered are:the resonance decay,the flavor dependence of the quark elliptic flow and the combination of quarks/antiquarks with slightly different transverse momenta.Our results show that the deviations observed in experiments can be well reproduced within the combination framework if all the three effects are considered. We make a detailed analysis of the different contributions using a Monte-Carlo program and suggest measuring the quark number scaling in intermediate pT range more precisely.     

Magnetic and Transport Properties of Tm2Co7B3 Compound

Magnetic and transport properties of Tm₂Co₇B₃ compound have been studied. This compound crystallizes in the hexagonal Ce₂Co₇B₃ type structure. The coercivity (H _c) of the compound was determined from hysteresis measurements in fields up to 4 T. The temperature dependence of coercivity has been explained by a thermally activated process of domain wall motion. The resistivity at low temperatures shows a T ² dependence. At higher temperatures the resistivity is not a linear function of temperature, which indicates an electron-phonon interaction in the presence of a small s-d scattering.     

Structural and Physical Properties of New Conducting Cation Radical Salts with Te-Based Counteranions, Tetraiodotellurate(II) and Hexaiododitellurate(II)

This article reports preparation, structure, and conducting property of several cation radical salts of organic donors tetramethyltetrathiafulvalene (TMTTF), ethylenedithiotetrathiafulvalene (EDT-TTF), bis(ethylenedithio)tetrathiafulvalene (ET), bis(ethylenedithio)tetraselenafulvalene (BETS) and hexamethylenetetraselenafulvalene (HMTSF) with two novel planar Te-based dianions, TeI₄²⁻ and Te₂I₆²⁻. (ET)₅Te₂I₆ 1 and (BETS)₅Te₂I₆ 2 are isostructural. In these Te₂I₆²⁻ salts, intermolecular short I···I contacts form a supramolecular corrugated anion sheet. Donor arrangement is similar to the θ-type. With lowering temperature, the resistivity of 1 shows a gradual increase followed by a sharp upturn at 110 K. 2 is metallic down to 120 K and shows a gradual increase of the resistivity followed by a clear transition to an insulating state around 60 K. Crystal structure of (ET)₄TeI₄ 3 is based on the “herring bone” arrangement of ET molecules similar to the α-type. 3 shows a semiconductive behavior around room temperature followed by a transition to an insulating state at 210 K. (EDT-TTF)₄TeI₄ 4, a semiconductor, exhibits a unique two-dimensional arrangement of dimerized EDT-TTF molecules.     

射频溅射法制备Pb_(1-x)Co_xSe薄膜及物性研究

利用复合靶共溅射法制备了半磁性半导体 Ｐｂ１－ ｘ Ｃｏｘ Ｓｅ 薄膜．研究了薄膜的成分结构以及电阻率温度特性和磁化率温度特性间的关系．结果表明：由于 Ｃｏ 离子介入, Ｐｂ１－ ｘ Ｃｏｘ Ｓｅ 发生了由金属特性向半导体特性的转变,在充分低的温度下,并伴有磁相转变．磁相转变温度与磁性离子浓度相关,磁化率的相对变化幅度与磁性离子浓度有关     

Tailoring magnetism in artificially structured materials: the new frontier

The current standard of electronic devices and data storage media has reached a level such that magnetic materials have to be fabricated on a nanometer scale. In particular, the emerging concept of spintronics, which is based on fact that current carriers have not only charge but also spin, requires the assembling of nanometer-sized magnetic structures with desired magnetic properties. It is this background that motivates scientists and engineers to attempt to grow and characterize magnetic objects at smaller and smaller length scales, from 2D films and multilayers to 1D wires and eventually to 0D dots. In this article, some of the most significant progress in recent years in the effort of growing artificially structured magnetic materials are reviewed. The new structural and magnetic properties of these materials are discussed, with an emphasis on the correlation between structure and magnetism, which also serves as guidance for improving their magnetic properties. The emerging emphasis is on converting the existing knowledge into growing and studying low-dimensional complex materials, which promise to have considerably higher “tuning” ability for desired properties.