Mechanical, electrical and spectroscopic investigations of carbon nanotube-reinforced elastomers

This paper reports investigations carried out on elastomeric matrices filled with multiwall carbon nanotubes. A comparison with carbon black-filled polymers is also made. The state of dispersion of the fillers in the polymer matrix is evaluated through transmission electron and atomic force microscopies. Stress–strain measurements of the composites demonstrate that carbon nanotubes bring significant improvements in the mechanical properties with regard to the pure polymer. Infrared and Raman spectroscopies are shown to bring molecular insights into the structure/property correlations. Electrical properties of the filled materials are also analyzed in order to determine the so-called percolation threshold and the insulator–conductor transition corresponding to the formation of an interconnected filler network throughout the matrix.     

Nuclear structure of neutron-rich nuclei near closed shells from excited-state g-factor measurements

New techniques to measure the g factors of picosecond-lived excited states of neutron-rich nuclei produced as radioactive beams are discussed along with their applications to study nuclear structure near ¹³² ₅₀Sn₈₂ and in the region between N=20 and N=28.     

Oxygen permeation studies on La0.8Sr0.2Ga0.75Mg0.15Co0.10O3±δ

Oxygen permeation measurements were carried out on La_0.8Sr_0.2Ga_0.75Mg_0.15Co_0.10O_3±δ specimens of different thickness at temperatures between 673 and 1173 K under various gradients of oxygen partial pressure. Simultaneously, the open circuit cell voltage was measured. It was shown that the investigated compositions were characterized by a high oxygen permeation rate, and, consequently, by a high electronic conductivity. The electrode polarization effect was experimentally proved, and the influence of the measurement conditions on the degree of the electrode polarization effect was studied and discussed in detail. In particular, this mentioned influence was found to be sufficiently smaller at higher oxygen partial pressures in the cathode (oxygen-rich) compartment, while the change of p_O2 on the anode (oxygen-lean) side of the permeation cell did not lead to any sufficient electrode polarization. The values of the hole conductivity calculated from the experimental results found to be at least influenced by electrode polarization were used for calculations of the hole conductivity. The comparison of these values with results obtained by other experimental techniques (by p_O2-dependence of the total conductivity measured using impedance spectroscopy and Hebb–Wagner-polarization technique) demonstrated a satisfactory agreement.     

Spin-parity measurements in the neutron-rich N ∼ 20 34P and 36S nuclei

Yrast and near-yrast energy levels in the neutron-rich N ∼ 20 nuclei ³⁴P, ³⁶S were populated using transfer/deep-inelastic processes following the ³⁴S + ¹¹⁵In reaction at an incident energy of 140MeV. The use of a multi-clover array has facilitated polarization measurements of the observed γ-rays and necessitated some changes in the previously known level scheme. The observation of the negative-parity levels in these nuclei on the periphery of the “island of inversion” is indicative of the influence of the intruder orbitals on the level structure at low spins. Shell-model calculations indicate that the inclusion of the orbitals from the upper pf shell is important even for the low-lying positive-parity states.     

Size dependence of lattice parameter for SixGe1−x nanoparticles

The phenomenon of the influence of the size of a material on its properties has been predicted theoretically and was confirmed for many materials experimentally by many researchers. It is a purpose of this paper to increase understanding of the influence of size on properties for silicon, germanium and alloy silicon-germanium nanoparticles. The relationships between lattice parameter and inverse particle radius had been investigated. The data obtained from the experiments show an unpredicted result that the lattice parameter of the Si_xGe_1−x nanoparticle expands by up to 1.5% when the size of the particle decreases to 7 nm. A calibration technique for a higher precision measurement of the lattice parameter is presented. The particles under investigation were deposited on an amorphous carbon substrate in order to prevent the influence of the misfit between deposit and crystalline substrate on the particle’s behavior.     

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设计了一个取样位置能在射频辉光放电等离子体电极间自由移动的取样装置,用质谱计测量了SiCl4等离子体的离子信号。提出了一种线性拟合的方法用于计算SiCl4等离子体的消耗率,利用测量的离子信号,计算出了SiCl4等离子体中SiCln(n=0~2)中性基团的空间分布。实验结果表明,可移动质谱取样装置的设计是合理的;用线性拟合方法得到的等离子体消耗率和中性基团的相对密度,比以前的方法得到的更精确。     

Combined AFM and two-focus SFCS study of raft-exhibiting model membranes.

Dioleoylphosphatidylcholine/sphingomyelin/cholesterol (DOPC/SM/cholesterol) model membranes exhibit liquid-liquid phase separation and therefore provide a physical model for the putative liquid-ordered domains present in cells. Here we present a combination of atomic force microscopy (AFM) imaging, force measurements, confocal fluorescence imaging and two-focus scanning fluorescence correlation spectroscopy (two-focus SFCS) to obtain structural and dynamical information about this model membrane system. Partition coefficients and diffusion coefficients in the different phases were measured with two-focus SFCS for numerous fluorescent lipid analogues and proteins, while being directly related to the lateral organization of the membrane and its mechanical properties probed by AFM. Moreover we show how the combination of these different approaches is effective in reducing artifacts resulting from the use of a single technique.     

Measurements of cross-sectional instantaneous phase distribution in gas–liquid pipe flow

Two novel complementing methods that enable experimental study of gas and liquid phases distribution in two-phase pipe flow are considered. The first measuring technique uses a wire-mesh sensor that, in addition to providing data on instantaneous phase distribution in the pipe cross-section, also allows measuring instantaneous propagation velocities of the phase interface. A novel algorithm for processing the wire-mesh sensor data is suggested to determine the instantaneous boundaries of gas–liquid interface. The second method applied here takes advantage of the existence of sharp visible boundaries between the two phases. This optical instrument is based on a borescope that is connected to a digital video camera. Laser light sheet illumination makes it possible to obtain images in the illuminated pipe cross-section only. It is demonstrated that the wire-mesh-derived results based on application of the new algorithm improve the effective spatial resolution of the instrument and are in agreement with those obtained using the borescope. Advantages and limitations of both measuring techniques for the investigations of cross-sectional instantaneous phase distribution in two-phase pipe flows are discussed.     

Prediction of optical properties of paints

The field of predictive rendering concerns itself with those methods of image synthesis which yield results that do not only look real, but are also radiometrically correct renditions of nature, i.e., which are accurate predictions of what a real scene would look like under given lighting conditions. A real coating consists of pigments, effect pigments, clear lacquer and glaze. A novel and unique combination of real parameters that are commonly measured in the industry and a theoretical reflectance model consisting of measurable parameters is required. Here, the authors design perception parameters and put them into well known surface reflection functions such as He and Torrance. The original contributions are the study of the sub-surface scattering of real paint and the prediction of its appearance in rendered images by the proposed model of light reflection beneath the paint surface. Presented at 5-th International Conference Solid State Surfaces and Interfaces, November 19–24, 2006, Smolenice Castle, Slovakia