Anisotropic photoconduction in dye-sensitized Langmuir films

Lateral charge transport has been observed in Langmuir multilayer films with a surface-active merocyanine dye by measuring the photoconduction in a gap cell configuration. The lateral photoconductivity Δσ_∥ is found to be 10³–10⁴ times larger than the photoconductivity Δσ_⊥ in the normal direction evaluated for sandwich cells at higher levels of illumination. A square root dependence on intensity is observed for both photoconductivities at these higher intensity levels. On decreasing the light intensity, Δσ_∥ varies linearly, while Δσ_⊥ continues to obey the square root law. These results are consistent with the hopping model for multilayer systems which has so far been developed.     

Cationic Copolymer‐Chaperoned 2D–3D Reversible Conversion of Lipid Membranes

Nanosheets have thicknesses on the order of nanometers and planar dimensions in the micrometer range. Nanomaterials that are capable of converting reversibly between 2D nanosheets and 3D structures in response to specific triggers can enable construction of nanodevices. Supra‐molecular lipid nanosheets and their triggered conversions to 3D structures including vesicles and cups are reported. They are produced from lipid vesicles upon addition of amphiphilic peptides and cationic copolymers that act as peptide chaperones. By regulation of the chaperoning activity of the copolymer, 2D to 3D conversions are reversibly triggered, allowing tuning of lipid bilayer structures and functionalities.     

Effects of MgO addition on sintering of calcium phosphate ceramics and composites

Bioactive ceramics attracts much attention as materials for bone implants, because of their high biocompatibility. For example, hydroxyapatite (HA) has bone-bonding ability through a bone-like apatite layer in body environment and β-tricalcium phosphate (β-TCP) has a high bioresorbability in body environment. In addition, HA/β-TCP composites has the characteristics of both HA and TCP. However, it is difficult to sinter the composite, so that MgO has been used as a sintering agent. In the present study, effects of MgO addition on sintering calcium phosphate ceramics and composites were investigated. In order to evaluate the effect of MgO on the composites, HA, HA/β-TCP(30wt%), and HA/β-TCP(50wt%) with 1wt% MgO were prepared and characterized. To clarify the role of MgO on sintering of calcium phosphate ceramics, HA, β-TCP, and α-TCP with different TCP content (0, 1, 2, 3, 4, and 5 wt%) were also prepared. The results suggest that MgO addition densified HA/β-TCP composites and gave higher strength composites. The results of monolithic calcium phosphate ceramics indicated MgO addition was effective on β-TCP and α-TCP, not on HA. The maximum content of Ca atom in β-TCP displaced with Mg atoms in MgO might be 24 atm%.     

Real-time observation of surface charging on a cylindricalinsulator in vacuum

By using an electrostatic probe located close to the triple junction on the cathode surface, we have conducted real-time observations of the change in electric field due to surface charging of an insulator in vacuum. A cylindrical sample made of polymethylmethacrylate (PMMA) or Al₂O₃ has been exposed to HVDC. An axisymmetric simulation based on the secondary electron emission electron avalanche (SEEA) theory has been performed. The measured results agreed with the simulation concerning the polarity of the accumulated charge as well as the field strength. The simulation also predicts the inception of charging at a voltage well below the measured flashover voltage. These results clearly support the SEEA theory as a macroscopic mechanism of surface charging of an insulator in vacuum     

Grain-size analysis of fine and coarse non-plastic grains: comparison of different analysis methods

Grain size is a fundamental property of earth materials. Many techniques for measuring grain size exist, and elucidating the relationships among the different analysis techniques is valuable for understanding what constitutes grain size. In this study, grain-size distributions obtained through dry-mode digital particle imaging using optical microscopy, laser diffraction (LD), and hydrometer sieving (HS) were compared. For most of the investigated samples, the three methods yielded similar size distributions. When performing dry-mode particle optical imaging (DMPOI) measurements of grain size, we recommend using high dispersion pressure. The grain-size distribution curves of finer sands were shifted toward coarser particles in the DMPOI analysis results, compared to the LD and HS results. In contrast, the grain-size distribution curves of glass beads (irrespective of size) were similarly shaped in all three cases. The fractions of sand and silt sizes were relatively consistent among the three methods, but were smaller in the DMPOI results than in the LD and HS results. The median particle size (8–280 µm) was similar among the three methods. DMPOI yielded a lower standard deviation than the other methods. In the HS analysis of the mica sample (consisting of platy layer particles), the curve was clearly shifted toward finer particles, and the granulometric characteristics differed significantly from those obtained using the other methods. Therefore, the three methods appear to differ mainly in terms of their physical interpretations of “grain size” and the effects of the distribution width and high-sensitivity circularity of the particles.     

Incidence of open crack formation in short-grain polished rice during soaking in water at different temperatures

The incidence of open crack formation in short-grain polished rice during soaking in water at different temperatures was investigated. Rice with a moisture content of 10.4% (wet basis) was soaked in distilled water for 90 min at 15 °C, 25 °C or 35 °C, and the rate of open crack formation and the moisture content of the rice during soaking were measured. Results show that the rate of open crack formation increased with decreasing the soaking temperature. A model based on the relationship between the tensile stress calculated from the moisture gradient in a rice grain and the tensile strength calculated from the average moisture content of a rice grain provided a reliable qualitative estimate of the difference in the rate of open crack formation at different temperatures. It can be concluded that water diffusion into rice grains should be accelerated to prevent the formation of open cracks.     

Pediococcus pentosaceus NB-17 for probiotic use

The plant-derived Pediococcus pentosaceus NB-17 was isolated from Japanese traditional vegetable pickles. The production of cytokines from mouse spleen cells co-cultivated with heat-killed bacteria was investigated in vitro. The bacteria significantly induced secretion levels of interferon (IFN)-gamma and interleukin (IL)-12 p70, and suppressed IL-4 productions in ovalbumin (OVA) sensitized mouse spleen cells. Therefore, the bacteria could effectively stimulate immune activities and showed allergic inhibitory effects. Further study on acid tolerance was performed under simulated gastric conditions and NB-17 showed resistance to simulated gastric acidity at pH 3.0 and pH 2.5. Moreover, after oral administration of the intact cells to rats, bacterial colonies derived from feces were analyzed by random amplification polymorphic DNA (RAPD). It was confirmed that the administered strain NB-17 remained alive in feces. These results suggest the possibility to use the P. pentosaceus NB-17 as functional foods.