Structural Defects Control the Energy Level Alignment at Organic/Organic Interfaces

The dependence of the energy level alignment (ELA) on structural defects at an organic/organic heterojunction (OOH) of perfluoropentacene (PFP)‐on‐diindenoperylene (DIP) was investigated using X‐ray scattering and ultraviolet photoelectron spectroscopy. The density of structural defects near the interface between the PFP and DIP layers was varied by changing the growth temperature of the DIP film. A direct relationship was found between the defect density and the ELA at the OOH; the ELA together with the change in the electrostatic potential (quasi‐interface dipole layer) at the OOH varies systematically with the defect density near the interface. This indicates that a key factor affecting the ELA is the electrostatic potential change across the OOH interface, which is produced by electron transfer from DIP occupied gap states to PFP unoccupied gap states. These gap states originate from the defects and are effectively controlled by adjusting the growth conditions of the organic films. As a result, the ELA at OOH interfaces can be controlled by the density of structural defect, which is important for organic devices employing OOHs, such as organic photovoltaic cells.     

Synthesis and electrical properties of sodium bismuth niobate Na0.5Bi2.5Nb2O9

The crystal structure of Na_0.5Bi_2.5Nb₂O₉ was refined from its powder X-ray diffraction (XRD) data. Sodium bismuth niobate at 23 °C is orthorhombic, A2₁am, with a=5.4998(3) Å, b=5.4602(2) Å, c=24.952(1) Å, and Z=4. The piezoelectric properties were investigated using the dense bulk ceramics. The electromechanical coupling coefficients (k_ij) and electrical quality factors (Q_m) are k₃₁=3.2%, k_t=10.0%, and Q_m=3800. Single crystals were also grown from stoichiometric melts using a slow cooling technique. The dielectric and ferroelectric properties of the crystal indicates that a spontaneous polarization clearly occurs in the crystallographic a-b plane.     

Melt memory effects on recrystallization of polyamide 6 revealed by depolarized light scattering and small‐angle X‐ray scattering

Melt memory effects on recrystallization of polyamide 6 were studied in a length scale from nm to μm using small‐angle X‐ray scattering (SAXS) and depolarized light scattering (DPLS). The memory effects on recrystallization rate were discussed in terms of the incubation period before nucleation and the half time of the crystallization, which were measures of the nucleation rate and the growth rate, respectively. Both rates are almost independent of the annealing temperature of the melt in the remelting process for the short term annealing below ～ 3 min while they are slowed as the annealing temperature increases for the long term annealing, showing that the relaxation of melt memory takes very long even above the equilibrium melting temperature T. Extrapolating the incubation period to infinite annealing, time we found that it was very hard to attain the fully relaxed state in polyamide 6 even above the equilibrium melting temperature. This must be due to the strong hydrogen bonding in polyamide 6. We also discuss the memory effects on the final structure after recrystallization based on the SAXS and DPLS profiles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of Grain Size and Grain Orientation on Dislocations Structure in Tensile Strained TWIP Steel During Initial Stages of Deformation

The effects of grain size and grain orientation on substructure in Fe–31Mn–3Al–3Si TWIP steel at a true strain of 0.06 were investigated. The results of the TEM observations indicated that where the grain size was 18.4 µm, the dislocations structure showed orientation dependence so that the mixture of both planar and tangled dislocations structure can be found in the deformed structure before the mechanical twinning initiation. Regardless of the grain orientation, however, the dislocation entanglements were mainly observed in the case of 2.1 µm grain size. Additionally, the reason for the suppression of the mechanical twinning as a result of the grain refinement at higher strains was described by the change of dislocations structure during initial stages of deformation.     

A Successful Application of Job Enlargement/Enrichment at Toyota

When designing a production system to meet the company desires, the desire of the workers should also be considered. A survey at the Toyota Tsutsumi plant indicated that workers wanted enlarged/enriched jobs. The jobs were enlarged/enriched through a system of cross-training and job rotation. Productivity and quality were improved.     

Web access monitoring mechanism via Android WebView for threat analysis

Many Android apps employ WebView, a component that enables the display of web content in the apps without redirecting users to web browser apps. However, WebView might also be used for cyberattacks. Moreover, to the best of our knowledge, although some countermeasures based on access control have been reported for attacks exploiting WebView, no mechanism for monitoring web access via WebView has been proposed and no analysis results focusing on web access via WebView are available. In consideration of this limitation, we propose a web access monitoring mechanism for Android WebView to analyze web access via WebView and clarify attacks exploiting WebView. In this paper, we present the design and implementation of this mechanism by modifying Chromium WebView without any modifications to the Android framework or Linux kernel. The evaluation results of the performance achieved on introducing the proposed mechanism are also presented here. Moreover, the result of threat analysis of displaying a fake virus alert while browsing websites on Android is discussed to demonstrate the effectiveness of the proposed mechanism.

     

Grain size effect on high-speed deformation of Hadfield steel

The influence of the microstructure on the tensile properties and fracture behavior of Hadfield steel at high strain rate were studied. Hadfield steel samples with different mean grain sizes and carbon phases were prepared by rolling at medium temperatures and subsequent annealing. A sample with an average grain size larger than 10 μm, and a small number of carbides shows ductility with local elongation (post uniform elongation) at a high-speed tensile deformation rate of 10³ s⁻¹. In addition, the fracture surface changes from brittle to ductile with increasing strain rate. In contrast, a fine-grained sample with carbides undergoes brittle fracture at any strain rate. The grain size dependence is discussed by considering the dynamic strain aging as well as the emission of dislocation from cracks. The accelerated diffusion of carbon due to grain refinement is considered as one of the important reason for brittle fracture in the fine-grained Hadfield steel.     

Relationship between the local dynamics and gas permeability of polyacetylenes containing polymethylated indan/tetrahydronaphtalene moieties

Local dynamics of polyacetylenes having polymethylated indan/tetrahydronaphthalene moieties have been studied using quasielastic neutron scattering, and the results obtained have been discussed together with former results with various poly(diphenylacetylene) derivatives. Clear quasielastic scattering was observed for the present polymers although they were in the glassy state, and the observed dynamic scattering laws were well fitted to a model function assuming the sum of narrow and broad Lorentzians. Both the relaxation rates and fractions from the narrow component exhibited a positive correlation with oxygen permeability coefficients (PO₂)$\left(P_{{\text{O}}_2}\right)$, while those from the broad component hardly related to PO₂$P_{{\text{O}}_2}$. Furthermore, the local flux, which is defined as the product of fraction and relaxation rate of the narrow component, is also found to be proportional to PO₂$P_{{\text{O}}_2}$. These findings imply that only the narrow component contributed to the gas permeability. Thus, it has been clarified that the local dynamics with a time scale of several tens of picoseconds plays a role of key importance for the gas permeability of substituted polyacetylenes in the glassy state.