Foam performance of fatty acid soaps of odd carbon numbers

The foam capacities, foam stabilities, expanding single bubble stabilities, surfact tensions, and surface viscosities of the straight chain C₉–C₁₄ sodium soaps were measured at various concentration. The C₁₂–C₁₄ soaps, most notably the C₁₃, gave the best over-all foam performance of the compounds studied. The critical micelle concentrations for these soaps were also determined.     

Shape control of TIG arc plasma by cusp-type magnetic field with permanent magnet

The shape of arc plasma in gas-shielded arc welding is an important factor for the quality and efficiency of the welding. The arc plasma changes its shape by an external magnetic field because the arc is a flow of electricity and is subjected to the electromagnetic force. In this study, we examined the control of arc plasma by a cusp-type magnetic field. The field produces a high and low magnetic area alternatively, and changes the cross-section of the arc plasma from a circular to an elliptical shape. The previous study using solenoid coils to produce a cusp-type magnetic field reported that magnetized arc plasma provided deeper penetration. However, the solenoid device developed for the cusp magnetic field was too large in comparison with the size of the welding torch used for production welding. Therefore, this study investigated the magnetic control of arc plasma with permanent magnets that have recently become smaller in size and higher in intensity. Theoretical analysis model was constructed to determine the optimum arrangement of the magnets. This analysis requires a three-dimensional numerical model because the temperature-, velocity-, and electromagnetic fields of arc plasma change three-dimensionally by the additional magnetic field. It was analytically and experimentally shown in TIG arc welding that the arc shape could be elliptical cross-section even using the permanent magnets. Furthermore, our analysis showed that the effective magnetization direction of magnets was vertical, and this result was confirmed experimentally. As a result, we obtained the good bead appearance in the high-speed welding with this magnetic control.     

Measurement of effective atomic numbers using energy-resolved computed tomography

For ion radiation therapy, the measurement of effective atomic numbers, Z_eff, is necessary to know the material distribution in a human body; the range of ions entering the human body is influenced by the material distribution along their paths. Z_eff, however, cannot be measured at hospitals because monochromatic X-rays with different energies are necessary and are used only at synchrotron facilities. To make Z_eff measurements at hand, we propose energy-resolved computed tomography (CT) using a “transXend detector”. By assigning two narrow energy ranges in the unfolding process of the data obtained by the transXend detector, Z_eff for acrylic and aluminum can be estimated by energy-resolved CT. The estimated Z_eff are compared with those obtained by dual-energy and monochromatic X-ray CT.     

Hydrogen fermentation properties of undiluted cow dung

Anaerobic treatment of undiluted cow dung (15% total solids), so-called dry fermentation, produced hydrogen (743 ml-H(2)/kg-cow dung) at an optimum temperature of 60 degrees C, with butyrate and acetate formation. The hydrogen production was inhibited by the addition of NH(4)(+) in a dose-dependent manner. A bacterium with similarity to Clostridium cellulosi was detected in the fermented dung by a 16S rDNA analysis.     

Electrochemical crystallization of plasmonic nanostructures

We show how gold recrystallizes when under the influence of electrochemical potentials. This "cold annealing" occurs without charge transfer reactions and preserves nanoscale structural features. By performing the process on plasmonic nanostructures, grain growth is monitored noninvasively by optical spectroscopy. In this way, the influence from crystal structure on plasmon resonances can be investigated independently. Observed spectral changes are in excellent agreement with analytical models and changes in electron relaxation time and plasma frequency are calculated.     

Investigation of plasmon resonances in metal films with nanohole arrays for biosensing applications

Biosensing with nanoholes is one of the most promising applications of nanoplasmonic devices. The sensor properties, however, are complex due to coupled resonances through propagating and localized surface plasmons. This Full Paper demonstrates experimental and simulation studies on different plasmonic hole systems, namely various patterns of circular holes in gold films. In contrast to most previous work, here, the challenging situation of optically thin films is considered. The refractive-index-sensing properties, such as sensitive locations in the nanostructure and sensitive spectral features, are investigated. The multiple multipole program provides the complete field distribution in the nanostructure for different wavelengths. It is shown that the spectral feature most sensitive to refractive-index changes is the extinction minimum, rather than the maximum. The results are consistent with theory for perfect electrical conductors. The spectral response is investigated for molecular adsorption at different positions inside or outside a hole. Furthermore, the optical properties of nanohole arrays with long-range and short-range order are compared and found to demonstrate remarkable similarities. Our results help to predict the resonance wavelengths of nanoholes with arbitrary patterns, including short-range order. The results presented here are highly important since they extend and challenge several aspects of the current understanding of plasmon resonances in nanohole arrays. These theoretical models, simulation results, and experimental data together help provide the understanding necessary for the development of efficient biomolecular analysis tools based on metallic nanoholes.     

Size distribution measurement of floating particles in the Allen region by a buoyancy weighing-bar method

The particle size distributions of spherical or cylindrical solid particles in the Allen region were measured using a buoyancy weighing-bar method. The particle size distribution obtained in the buoyancy weighing-bar method agrees with those measured by a laser diffraction/scattering method and a sieving method. The present study demonstrates that a buoyancy weighing-bar method is suitable for measuring the particle size distribution of a floating solid in the Allen region.     

Validity of generic scenarios used in derivation of exemption levels for surface contamination considering transport-specific aspects

The exemption levels for surface contamination in units of Bq cm(-2) were derived by developing a new universal dose assessment model that consists of three generic scenarios assessed by considering manually, closely and remotely handled objects. In this paper, as part of the process of verifying the validity of these generic scenarios, annual doses that arise from transport-specific aspects are calculated. The maximum annual doses are found to be lower than 10 μSv, which is the bottom line of the exemption dose criterion. The result verifies the validity of the generic scenarios used in the previous derivation of exemption levels for surface contamination.     

Higher‐order structural analysis of nylon‐66 nanofibers prepared by carbon dioxide laser supersonic drawing and exhibiting near‐equilibrium melting temperature

Extended chains and/or extended chain crystals (ECC) are important structures for improving the mechanical properties of polymer fibers. ECC have so far been produced using specially prepared materials or manufacturing methods. In our study on the production of nanofibers by carbon dioxide (CO₂) laser supersonic drawing, we succeeded in producing nylon‐66 nanofibers having a high melting point near the equilibrium melting point (T_m⁰). Two melting points (T_m) of 260 and 276°C were observed for the nanofibers, with the latter temperature being close to the T_m⁰ (280°C) of nylon‐66. A nanofiber that was heat treated at 279°C for 10 min displayed a large stacked lamellar structure with an average crystal thickness of 140 nm. That value was close to the average molecular chain length of 212 nm, which was calculated from the average molecular weight of the nanofibers. It was inferred from these results that ECC corresponding to the average molecular chain length were present in the nanofibers. The CO₂ laser supersonic drawing process is applicable to general purpose thermoplastic polymers and uses a simple drawing system. It is expected that this drawing method will help to improve the fundamental performance of general purpose polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40361.