Role of adsorbed iodine into poly(vinyl alcohol) films drawn in KI/I2 solution

We have investigated the microstructure of the poly(vinyl alcohol) (PVA) films using small- and wide-angle X-ray scattering (SAXS and WAXS, respectively) techniques. The samples were uniaxially drawn in water or KI/I₂ aqueous solution and then dried in an air-oven at 333 K for 1 h prior to SAXS and WAXS measurements. It was found that for the films drawn in KI/I₂ solution PVA chains in the microfibrillar structure are more extended upon the film drawing compared to the case of the films drawn in pure water, which is resulted from the correlation function analysis on the SAXS data. Adsorbed iodines into the film were anticipated to act as junction points between the microfibrils via the formation of the PVA-iodine complexes.     

Radiation detector made of a high-quality polycrystalline diamond

Radiation detector was made of a high-quality CVD polycrystalline diamond composed of frost column like structure diamond grains, and induced charge distribution spectra and drift velocities were measured by using alpha particles. As a result, the CVD polycrystalline achieved maximum induced charge of 83% of HP/HT type IIa diamond. Moreover, the CVD crystal had lower charge loss on electrons compared with the HP/HT type IIa diamond. Drift velocities of electrons and holes were v_e = 7.7 × 10⁴ and v_h = 7.3 × 10⁴cm/s at an electric field of 20 kV/cm, respectively. In addition, response function measurement for 14 MeV neutrons was carried out.     

Oxygen Uptake and Release Mechanism of Lithium Manganese Ferrite in the Low Temperature Range of 573–773 K

Oxygen uptake and release of (Li,Mn) ferrite [LMF; (Li_0.60Mn_1.20Fe_1.20)_1−δO₄; δ= 0.007 to 0.033] was investigated concerning the relations between redox reactions of ferrite and cation migration. Mössbauer spectroscopy and X-ray diffractometry showed that some of the Li⁺ and Fe³⁺ ions migrated from the A sites to the B sites of the spinel-type structure and Mn⁴⁺ ions migrated from the B sites to the A sites during oxygen uptake at 573 K. The cation-deficient LMF formed by the oxygen uptake released oxygen molecules in He gas only at 660 K. The cation migration during the oxygen release was in the opposite direction of the movement during oxygen uptake at 573 K.     

Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte – Understanding the role of cathodic half-cycle in AC plasma electrolytic oxidation

Sequential anodic and cathodic pulse voltages were applied on anodised Al micro-electrodes in alkaline silicate electrolyte to explore the role of cathodic pulse in AC or bipolar plasma electrolytic oxidation (PEO) process. SEM observation was carried out to observe the sites of anodic and cathodic breakdown and their morphologies. The prior anodic breakdown accelerated the cathodic breakdown at ?50 V, and the acceleration was associated with the preferential cathodic breakdown at the anodic breakdown sites. However, the succeeding anodic breakdown during applying anodic pulse of 420 V for 2 ms was highly suppressed at the cathodic breakdown sites. This would randomise the anodic breakdown sites. Such role may contribute to the formation of rather uniform coatings on aluminium in this electrolyte without large discharge channels when larger cathodic current is applied with respect to the anodic current in AC PEO.     

Morphological reason for enhancement of electrochemical double layer capacitances of various acetylene blacks by electrochemical polarization

Enhancement of electrochemical capacitance and morphological variations of various acetylene blacks caused by electrochemical polarization are presented. Acetylene blacks of different mean particle diameters were modified by air-oxidation and heat treatment to diversify the morphologies of the acetylene blacks before electrochemical polarization. The various acetylene blacks were electrochemically oxidized at 1.6 V (vs. Ag/AgCl) for 10 s and the polarization step was repeated until the capacitance values did not change any longer. These polarization steps enhanced the capacitances of the acetylene blacks and the specific enhancement factors range from 2 to 5.5. Such an enhancement is strongly related to morphological modification as revealed by transmission electron microscopic observations. The electrochemical polarization resulted in formation of tiny graphene sheets on the wide graphitic carbon surfaces, which were most responsible for the observed capacitive enhancement. Although the pseudo-capacitance increased after polarization by forming oxygenated species on the surfaces, its contribution to the total capacitance was less than 10%. The mechanism of the formation of the tiny graphene sheets during the electrochemical oxidation is described schematically.     

Mathematical modelling of MAG welding

The development of laser welding technology has enabled the mass production of thin-walled structures, including steel sandwich panels. The technology of joining plating panels with stiffeners by welding allows us to create joints with a specific geometry and material properties. In comparison with other types of joints, laser welds are characterized by their specific behaviour under cyclic load and, as a consequence, a different model of fatigue damage. The basis of fatigue analysis of laser-welded joints was the determination of stress concentrations in the notches. For this purpose, a numerical finite element method model of a laser-welded joint was created. The article presents the main aspects of the numerical model and the results concerning the influence of the modelling method on the strain and stress distribution in the notches. For the weld root notch, the theoretical results have been compared with experimental data of strain distributions obtained by the laser extensometry grid technique.     

High permittivity BaTiO3 and BaTiO3-polymer nanocomposites enabled by cold sintering with a new transient chemistry: Ba(OH)2∙8H2O

Cold sintering process (CSP) offers a promising strategy for the fabrication of innovative and advanced high permittivity dielectric nanocomposite materials. Here, we introduce Ba(OH)₂?8H₂O hydrated flux as a new transient chemistry that enables the densification of BaTiO₃ in a single step at a temperature as low as 150 °C. This remarkably low temperature is near its Curie transition of 125 °C, associated with a displacive phase transition. The cold sintered BaTiO₃ shows a relative density of 95 % and a room temperature relative permittivity over 1000. This new hydrated flux permits the fabrication of a unique dense BaTiO₃-polymer nanocomposite with a high volume fraction of ceramics ((1-x) BaTiO₃ – x PTFE, with x = 0.05). The composite exhibits a relative permittivity of approximately 800, at least an order of magnitude higher than previous reports on polymer composites with BaTiO₃ nanoparticle fillers that are typically well below 100. Unique high permittivity dielectric nanocomposites with enhanced resistivities can now be designed using polymers to engineer grain boundaries and CSP as a processing method opening up new possibilities in dielectric materials design.     

An improved EZ-GCD algorithm for multivariate polynomials

The EZ-GCD algorithm often has the bad-zero problem, which has a remarkable influence on polynomials with higher-degree terms. In this paper, by applying special ideals, the EZ-GCD algorithm for sparse polynomials is improved. This improved algorithm greatly reduces computational complexity because of the sparseness of polynomials. The author expects that the use of these ideals will be useful as a resolution for obtaining a GCD of sparse multivariate polynomials with higher-degree terms.     

Tracking control properties of human-robotic systems based on impedance control

Human-robotic systems that include interaction between human operators and robots should be designed with careful consideration for the dynamic property and control ability of a human operator. This paper performs manual tracking control tests on a human-robotic system using an impedance-controlled robot, and investigates control characteristics of a human operator according to the robot impedance properties. Experimental results demonstrate that humans try to maintain dynamic properties of an overall system as constant as possible by adjusting their own impedance properties. Then, a new training system using a neural network for operating a human-robotic system is constructed on the basis of the experimental findings in the human tracking control properties.