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[en] A modified CR-39 microfilter with funnel-shaped pore entrances is produced by using a multi-step etching procedure with NaOH and PEWsub(x) solution (PEWsub(x) = 15g KOH + x g C2H5OH + (85 - x)g H2O) as etching agents. The air throughput through this microfilter is measured and compared with the CR-39 microfilter with cylinder-shaped pores and a commercial microfilter (Nuclepore). The experimental data of both CR-39 microfilters show a good agreement with the theoretical values for the air throughout contrary to the Nuclepore microfilter. Furthermore both CR-39 filters have an extremely plane surfaces and no roughness of the pore walls. (author)
[en] Hydrophobicity is known to play a key role in the biological distribution of materials but is often an overlooked parameter when conjugating targeting agents, drugs, and dyes to dendrimers. This review examines the impact of hydrophobic variation in stochastically conjugated dendrimers as well as materials where synthetic methods or approaches to purification provide more controlled samples. Hydrophobic interactions are considered for three general classes: (1) terminal functional group modifications, (2) bioactive small molecules chosen to interact with receptors and proteins as targeting agents and/or drugs, and (3) imaging agents to track biological activity. Impacts on membrane interaction and cellular uptake, biodistribution, interaction with transport proteins, and pharmacokinetics are discussed. The size range of the dendrimers discussed is ~ 1–10 nm.
[en] The particle tracking autoradiography(PTA) is a very useful method to investigate the boron distribution through the large sample area. The PTA method for boron uses the phenomenon that boron irradiated by neutron emits Li-ion and alpha particle; boron distribution can be obtained by observing the traces of the emitted particles. At HANARO in KAERI, a study for observing the boron distribution has been performed for several years. Recently, the experimental techniques were improved to provide reliable images for samples of various composition. In this report, the PTA method and experimental techniques were described in detail and the experimental results of the sample polishing, the amount of neutron irradiation and the etching time were reported. As a result, the optimum conditions for the analysis of boron distribution with respect to the amount of added boron were appeared
[en] Highlights: • A new analytical model for multi-material composites subject to rotary wear is developed for efficient wear predictions. • Numerical predictions of key wear characteristics for Aluminum/Epoxy composites agree well with the experimental findings. • Potential applications of the wear model for the design of composites subject to dry abrasive rotary wear are discussed. Due to the prevalence of sliding interfaces in mechanical assemblies, fast and reliable wear prediction capabilities are imperative for system design and analysis. This study investigates the rotary wear of multi-material composite systems that have thrust washer geometries. An analytical rotary wear model is developed to predict the rotary wear performance based on Archard's wear law and a Pasternak elastic foundation model. Numerical methods are used to track the evolution of key wear parameters including surface profile, contact pressure distribution, volume loss and composite wear rate during both run-in and steady-state wear regimes. A direct method is also developed to determine the steady-state characteristics from just the initial conditions and configurations of a given composite system. Optimal designs and design guidelines for several wear objectives are identified. Initial optimal material distributions for target steady-state surface profiles are determined. In addition, the steady-state composite wear rate is minimized to reduce material loss for bi-material systems with prescribed volume fractions. It is found that the optimal material configuration for this objective is counterintuitive. Wear tests are conducted to evaluate the proposed models and optimal design solutions. Results obtained from the wear models agree well with the experimental measurements.
[en] Optimal templating synthesis of nanoscale materials by filling the porosity of track etched membranes requires membranes with controlled and predictable pore size and geometry. In this paper, we mainly show that improvement of existing track etching technology allows a reliable and reproducible lab-scale production of nanoporous membranes with cylindrical pores exhibiting smooth wall
[en] This paper shows the possibility of preparing nanoporous particle track etched membranes (nanoPTM) with perfectly smooth and cylindrical pores from polycarbonate film. Interest in the template use of these nanoPTM for the production of polymeric or metallic nanoscale materials is also emphasized
[en] The Particle Tracking Autoradiography(PTA) technique based on the 10B(n, α)7Li fission reaction with a solid detector(LR115 film) has become a powerful tool for studying the behavior of boron distribution in materials. In this study, it is investigated in changing the method that the film on the specimen attach, the etching time to film and the surface roughness of the specimens
[en] The process of polymerisation of electrically conductive polypyrrole in pores of track-etched polyester membranes with different pore sizes was investigated. The wall thickness growth was studied as a function of the time of polymerisation and pore diameter. The wall thickness and the thickness of the surface layers were observed and measured by scanning electron microscopy (SEM). The kinetics of polypyrrole polymerisation is presented. Results enable to predict the thickness of the wall of polypyrrole nanotubules in pores of polyester membranes
[en] Experiments have been performed to study the annealing of nuclear tracks in some crystalline minerals viz. apatite, zircon and garnet. It is observed that the value of activation energy of track annealing depends upon the interatomic spacing. Some new results on activation energy of track annealing in crystalline minerals are reported. (author)