Structural characterizations of diglycerol monomyristate reverse micelles in aromatic solvent ethylbenzene

Using small-angle X-ray scattering (SAXS) we have investigated the shape and size of diglycerol monomyristate (designated as C14G2) nonionic surfactant reverse micelles in aromatic solvent ethylbenzene as a function of surfactant concentration, temperature, and water. When C14G2 is added into ethylbenzene globular type reverse micelles with maximum core diameter ca. 4.5 nm are formed under ambient conditions. The micellar structure (shape and size) did not change with the surfactant concentration. However, an increase in temperature decreased the micellar size due to an increase in the critical packing parameter (cpp). Surfactant becomes more lipophilic upon heating and the micellar curvature tends to become more negative at higher temperature. Addition of a small amount of water caused a significant micellar growth. For instance, incorporation of 0.3% water in the 5% C14G2/ethylbenzene system resulted in the formation of 2.1 time bigger micelles with a small water pool in the micellar core. Besides the micellar shape is modified into an ellipsoidal prolate, whose scenario can be understood in terms of hydration of the surfactant's headgroup. Hydration decreases the cpp and favors micellar growth. An increase of temperature of a water incorporated system decreased the micellar size due to dehydration, which is equivalent to rod-to-sphere type transition.     

Evaluation of Humidity Correction Factor of Disruptive Discharge Voltage of Standard Sphere Air Gaps

The humidity correction method prescribed in the existing IEC standard is based on experimental data obtained under absolute humidity between 5 and 12 g/m³. A discussion on the humidity correction method is needed for higher absolute humidity regions, which is experienced during summer in Japan, and also throughout the year in tropical countries. The effect of absolute humidity on disruptive discharge voltages of standard sphere air gaps has been studied experimentally for several years under conditions of natural humidity, between 2 and 22 g/m³. In the cases of a.c. and lightning impulse voltage application, it was found that the existing IEC humidity correction method seems to be proper for most of the gap spacings studied under absolute humidity up to 22 g/m³. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Fatigue limit of carbon and CrMo steels as a small fatigue crack threshold in high-pressure hydrogen gas

The fatigue limit properties of a carbon steel and a low-alloy CrMo steel were investigated via fully-reversed tension-compression tests, using smooth specimens in air and in 115-MPa hydrogen gas. With respect to the CrMo steel, specimens with sharp notches were also tested in order to investigate the threshold behavior of small cracks. The obtained SN data inferred that the fatigue limit was not negatively affected by hydrogen in either of the steels. Observation of fatigue cracks in the unbroken specimens revealed that non-propagating cracks can exist even in 115-MPa hydrogen gas, and that the crack growth threshold is not degraded by hydrogen. The experimental results provide justification for the fatigue limit design of components that are to be exposed to high-pressure hydrogen gas.     

Development of butt welding of polymeric materials based on softening and stirring effects by hot tool

In this study, new butt welding technique was proposed to join polymeric materials in which the polymeric material is softened by a heated tool due to the Joule effect heating of the electric current flow through the tool, and the coalescence of material is done by the stirring action due to the tool rotation. A 3 mm-thick Polycarbonate (PC) sheets were joined in various joining conditions, from which joining mechanism, mechanical properties of joints and process parameters affecting joint performance were investigated. In the experiments, in situ observation with a CCD camera and material temperature measurement during the process, as well as the observation of surface appearance and cross section of the joint and tensile test were performed for these purposes. It was shown from the in situ observation and material temperature measurement that the molten and softened region is formed around the weld tool. It was also shown that sufficient heat input was required to form sound joints with acceptable performance, which depended upon the joining speed and amount of electric current flow through the tool. The observation of joint appearance and cross section revealed that the joint with comparable thickness to base material was obtained under the condition of revolution pitch below 0.08 mm, defined by the ratio of joining speed to tool rotation. It is noticed that joints obtained from the proper conditions have the same mechanical properties as the base material, and that the process parameters of this method were tool rotation speed, welding speed and amount of electric current. These results suggest proposed method is useful for joining the polymeric materials.     

Microstructural changes in weld metal during isothermal process. Study of reheat cracking in flux‐cored arc welding stainless steel weld metal (5th report)

The soiling of the slag, spatter and the fume, etc., which come into contact with the steel sheet surface with welding, is cleaned making use of steel sphere shot material of large particle diameter, high projection pressure with strong peening processing (below, called strong peening cleaning). In this research, the cleaning state of the soiling with welding and improvement of fatigue strength of the hot galvanized welded joint was inspected, when the surface of a SM490A welded joint was cleaned with strong peening cleaning.

The following experimental results were obtained:

1. The fatigue limit of smooth base metal which received strong peening cleaning at about 320 MPa was remarkably high in comparison with smooth base metal at about 245 MPa.

2. The fatigue limit of a welded joint which received strong peening cleaning at about 300 MPa was remarkably high in comparison with a welded joint at about 170 MPa.

3. The strong peening cleaning was highly efficient and the cleaning state was satisfactory.

4. The cause of the remarkable rise of the fatigue limit (300 MPa) of the welded joint which received strong peening cleaning was because the fatigue limit (about 170 MPa, 57%) of the welded joint was improved (about 130 MPa, 43%) with peening cleaning. It was considered that improvement effects were: a rise (about 68 MPa, 23%) of hardness of the weld toe; relief (about 43 MPa, 14%) of stress concentration; increase (about 136 MPa, 45%) of compressive residual stress; and the decrease (about ? 96 MPa, ? 32%) by increase of surface roughness.

5. The fatigue strength of the hot galvanized welded joint decreased remarkably. This was thought to be due to the decrease (about HV40) of hardness of the surface, the decrease (about 188 MPa) of the compressive residual stress and the influence of many factors which accompanied hot galvanizing.

     

Dependence of vacancy concentration on morphology of helium bubbles in oxide ceramics

Since the formation of helium bubbles degrades swelling property and thermal conductivity of minor actinide-containing mixed oxide (MA-MOX) fuel, it is essential to understand the conditions of the bubble formation. In order to examine the dependence of vacancy concentration on morphology of helium bubbles, helium was infused into (Zr,Fe)O_2?x. The oxygen vacancy concentration was controlled by addition of solute Fe³⁺ into ZrO₂. Helium was infused by hot isostatic pressing. The helium-infused specimens were observed by field emission scanning electron microscopy (FE-SEM) and field emission transmission electron microscopy (FE-TEM). In addition, X-ray fluorescence, X-ray diffraction analysis, conversion electron yield–X-ray absorption near-edge structure and FE-SEM/EDX (energy dispersive X-ray) analyses were also made to interpret the results of microstructure observations. As a result of the helium infusion treatment, numerous 0.5–10 nm bubbles were observed and its number density clearly depended on oxygen vacancy concentration. On the other hand, sizes of the helium nano-bubbles in all specimens were almost constant.     

Differences of drivers' reaction times according to age and mental workload

This study was designed to examine differences in reaction times of drivers of various age groups and to assess the influence of mental workload on reaction times. Experiments were performed on a simulated street and under other conditions to identify drivers with long reaction times and drivers whose reaction times are affected strongly by mental workloads while driving on a public road. Reaction times after hearing a buzzer were measured under five conditions: (1) sitting in a stationary vehicle, (2) executing mental calculations in a stationary vehicle, (3) driving on a simulated street, (4) executing mental calculations while driving on a simulated street, and (5) driving on a public road. Subjects were 10 drivers each of three age groups. Each experiment was performed by these subjects under the five conditions. Results showed that mental calculations increased the average reaction time for each age group. Mental calculations increased differences among age groups and individuals, and increased differences in respective drivers' individual performance. Mental calculations influenced elderly drivers' reaction times remarkably. Results also demonstrated that an experiment on a simulated street identified drivers who showed long reaction times on a public road.     

Electrochemical decomposition of CO2 and CO gases using porous yttria-stabilized zirconia cell

Electrochemical decomposition of CO₂ and CO gases using a porous cell of Ru-8 mol% yttria-stabilized zirconia (YSZ) anode/porous YSZ electrolyte/Ni–YSZ cathode system at 400–800 °C was studied by analyzing the flow rate and composition of outlet gas, current density, and phases and elementary distribution of the electrodes and electrolyte. A part of CO₂ gas supplied at 50 ml/min was decomposed to solid carbon and O₂ gas through the cell at the electric field strengths of 0.9–1.0 V/cm. The outlet gas at a flow rate of 3 ml/min included 61–63% CO₂ and 37–39% O₂ at 700–800 °C and the outlet gas at a flow rate of 50 ml/min included 73–96% (average 85%) CO₂ and 4–27% (average 15%) O₂ at 800 °C. On the other hand, the supplied CO gas was also decomposed to solid carbon, O₂ and CO₂ gases at 800 °C. The fraction of outlet gas at a flow rate of 50 ml/min during the CO decomposition at 800 °C for 5 h was 11–36% CO, 59–81% O₂ and 2–9% CO₂. The detailed decomposition mechanisms of CO₂ and CO gases are discussed. Both Ni metal in the cathode and porous YSZ grains under the DC electric field have the ability to decompose CO gas into solid carbon and O²⁻ ions or O₂ gas.     

Investigation of the antiviral properties of copper iodide nanoparticles against feline calicivirus

This study demonstrated the antiviral properties of copper iodide (CuI) nanoparticles against the non-enveloped virus feline calicivirus (FCV) as a surrogate for human norovirus. The effect of CuI nanoparticles on FCV infectivity to Crandell-Rees feline kidney (CRFK) cells was elucidated. The infectivity of FCV to CRFK cells was greatly reduced by 7 orders of magnitude at 1000μgml(-1) CuI nanoparticles. At the conditions, electron spin resonance (ESR) analysis proved hydroxyl radical production in CuI nanoparticle suspension. Furthermore, amino acid oxidation in the viral capsid protein of FCV was determined by nanoflow liquid chromatography-mass spectrometric (nano LC-MS) analysis. The use of CuI nanoparticles showed extremely high antiviral activity against FCV. The high antiviral property of CuI nanoparticles was attributed to Cu(+), followed by ROS generation and subsequent capsid protein oxidation. CuI nanoparticles could be proposed as useful sources of a continuous supply of Cu(+) ions for efficient virus inactivation. Furthermore, this study brings new insights into toxic actions of copper iodide nanoparticles against viruses.