Sorption of simple ions by nylon 6

The sorption isotherms of Na⁺ and Cl^? ions by nylon 6 from aqueous soluations at pH = 2.2, 4.0, and 6.0 are reported. Detailed analysis of the results showed that they could not be interpreted satisfactory by the classical Gilbert-Rideal or Donnan equilibrium treatments usually applied to nylon and/or wool. On a qualitative basis, the former model may be considered more successful, but, even so, the behavior of the partition coefficient of Na⁺ cannot be explained. This difficulty persists even when some important restrictions imposed by the simple Donnan equilibrium treatment are relaxed, as in the models of Glueckauf and of McGregor and Harris. A different theoretical viewpoint is put forward here, which explains the observed behavior qualitatively and shows how it fits into the general pattern of ion sorption by polyelectrolytes in general and by amphoteric polyelectrolytes in particular. The conclusions drawn also have important implications concerning previous interpretations of ion sorption by wool.     

Intestinal absorption and biological effects of orally administered amorphous silica particles

Although amorphous silica nanoparticles are widely used in the production of food products (e.g., as anticaking agents), there is little information available about their absorption and biological effects after oral exposure. Here, we examined the in vitro intestinal absorption and in vivo biological effects in mice of orally administered amorphous silica particles with diameters of 70, 300, and 1,000 nm (nSP70, mSP300, and mSP1000, respectively) and of nSP70 that had been surface-modified with carboxyl or amine groups (nSP70-C and nSP70-N, respectively). Analysis of intestinal absorption by means of the everted gut sac method combined with an inductively coupled plasma optical emission spectrometer showed that the intestinal absorption of nSP70-C was significantly greater than that of nSP70. The absorption of nSP70-N tended to be greater than that of nSP70; however, the results were not statistically significant. Our results indicate that silica nanoparticles can be absorbed through the intestine and that particle diameter and surface properties are major determinants of the degree of absorption. We also examined the biological effects of the silica particles after 28-day oral exposure in mice. Hematological, histopathological, and biochemical analyses showed no significant differences between control mice and mice treated with the silica particles, suggesting that the silica nanoparticles evaluated in this study are safe for use in food production.     

Investigation of hydrogen storage capacity of various carbon materials

Hydrogen storage capacity of various carbon materials, including activated carbon (AC), single-walled carbon nanohorn, single-walled carbon nanotubes, and graphitic carbon nanofibers, was investigated at 303 and 77 K, respectively. The results showed that hydrogen storage capacity of carbon materials was less than 1 wt% at 303 K, and a super activated carbon, Maxsorb, had the highest capacity (0.67 wt%). By lowering adsorption temperature to 77 K, hydrogen storage capacity of carbon materials increased significantly and Maxsorb could store a large amount of hydrogen (5.7 wt%) at a relatively low pressure of 3 MPa. Hydrogen storage capacity of carbon materials was proportional to their specific surface area and the volume of micropores, and the narrow micropores was preferred to adsorption of hydrogen, indicating that all carbon materials adsorbed hydrogen gas through physical adsorption on the surface.     

Toughening of cyanate ester resin by N‐phenylmaleimide–N‐(p‐hydroxy)phenyl‐maleimide–styrene terpolymers and their hybrid modifiers

N‐Phenylmaleimide–N‐(p‐hydroxy)phenylmaleimide–styrene terpolymer (HPMS), carrying reactive p‐hydroxyphenyl groups, was prepared and used to improve the toughness of cyanate ester resins. Hybrid modifiers composed of N‐phenylmaleimide–styrene copolymer (PMS) and HPMS were also examined for further improvement in toughness. Balanced properties of the modified resins were obtained by using the hybrid modifiers. The morphology of the modified resins depends on HPMS structure, molecular weight and content, and hybrid modifier compositions. The most effective modification of the cyanate ester resin was attained because of the co‐continuous phase structure of the modified resin. Inclusion of the modifier composed of 10 wt% PMS (M_w 136 000 g mol^?1) and 2.5 wt% HPMS (hydroxyphenyl unit 3 mol%, M_w 15 500 g mol^?1) led to 135% increase in the fracture toughness (K_IC) for the modified resin with a slight loss of flexural strength and retention of flexural modulus and glass transition temperature, compared with the values for the unmodified resin. Furthermore, the effect of the curing conditions on the mechanical and thermal properties of the modified resins was examined. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified cyanate ester resin system. © 2001 Society of Chemical Industry     

Effect of TiO2 on morphology and mechanical properties of PVDF/PMMA blend films prepared by melt casting process

Effect of titanium dioxide (TiO₂) on morphology and mechanical properties of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend films prepared at different TiO₂ contents by a melt casting process was studied. The results showed that tensile moduli in both the machine direction (MD) and the transverse direction (TD) increased with increasing TiO₂ content, and calculated tensile moduli based on the Halpin–Tsai and the Kerner model were consistent with experimental ones in both the MD and TD of films containing 10 wt % TiO₂. However, experimental tensile moduli exhibited smaller values compared with calculated ones, as the TiO₂ content increased to 30 wt %_, and it was assumed that this is due to the decrease of crystallinity of PVDF. Morphological observations indicated that TiO₂ particles did not affect crystal structures of PVDF and the morphology of PVDF/PMMA amorphous phase, but hindered the crystallization of PVDF. The MD and TD elongation at break exhibited >200 and <20%, respectively. The SEM micrographs revealed that spherulites could deform along the MD when the tensile force was applied along the direction. By contrast, spherulites could not deform along the TD and fractured at very small elongation, owing to the anisotropic morphology of spherulites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40454.     

Analysis of Organisation-Committed Human Error by Extended CREAM

This report analyses the results of the human error classification scheme of CREAM applied to organisation-committed human errors related to six departments. These human errors were not caused by the tasks spotlighted by CREAM, but were concentrated on managerial or administrative tasks, so that the authors have corrected and analysed the definitions and links of cause–effect relations related to the large organisation by means of an extended method of CREAM. Considering human errors on the basis of these analyses, findings have allowed the authors to come up with effective relations between organisation-related causal factors and person-related ones. This has demonstrated that organisation-caused human errors are sufficiently analysable by means of the extended method of CREAM.     

Remote sensing system for spatial electric field strength using free space light transmission

Most of the breakdowns in an electric power system are caused by lightning to the tower used for high‐voltage transmission wires. To avoid accidents due to lightning, it would be desirable to develop a measurement system for the spatial electric field distribution around the tower. We have developed a new system that can measure the electric field around the steel tower for electric power transmission by using an optical electric sensor. In conventional methods, the sensor is generally illuminated by light transmitted by optical fibers. On the other hand, the new measurement system illuminates the Pockels sensor directly by using a laser to measure the far electric field. Furthermore, our newly proposed feedback system makes it possible to measure the spatial electric field without concern for the change of Pockels sensor's operation point influenced by temperature change. This system is applicable as a remote sensing system to monitor the spatial electric field around a high‐voltage transmission line. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 10–19, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20552