Volume holographic imaging element with background noise reduction function for eye-gaze detection under white light illumination

Volume holographic optical element (VHOE) for imaging under white light illumination is integrated with imaging elements and background noise reduction filter. An integrated VHOE and the band pass filter which is optimized to the VHOE can develop the optical setup for a wearable eye-gaze detection system. An integrated VHOE is fabricated in photopolymer and then the effects of noise reduction filters as a function of the direction of the incident plane wave into an image sensor are evaluated. Experimental results show that the background noise reduction filter should be designed to reduce the incident light with wide direction of the transmitted light.     

Localized Yielding Around Crack Tips of Double‐Network Gels

Double‐network (DN) gels, a type of interpenetrating polymer network (IPN) consisting of rigid and flexible polymer components, exhibit two outstanding mechanical behaviors: yielding deformation of the entire specimen in tensile tests and quite high fracture energy in tearing tests. In this study, atomic force microscope (AFM) measurements were conducted on DN gels to determine the local Young's moduli immediately below the fracture surfaces E_f and below the usual molded surfaces E_m, and compare the local modulus with bulk Young's moduli measured before and after the yielding deformation, denoted as E_h and E_s, respectively. E_m and E_h are around 0.1 MPa; E_f and E_s, around 0.01 MPa, one order lower than the former two moduli. The order relation indicates that yielding deformation occurred locally around the crack tip of the DN gel during fracture. This supports the basic assumption of phenomenological models recently proposed to explain high fracture energy of DN gels. (H. R. Brown, Macromolecules 2007 , 40, 3815–3818; Y. Tanaka, Europhys. Lett. 2007 , 78, 56005).

     

Actin network formation by unidirectional polycation diffusion

We show that F-actins form three-dimensional giant network under uni-directional diffusion of polycations, at a dilute actin concentration (0.01 mg/mL) that only bundles are formed by homogeneous mixing with polycations. The mesh size of the actin network depends on polycation concentration and ionic strength, while bundle thickness of network depends only on ionic strength, which indicates that actin network is formed through nucleation-growth mechanism. The mesh size and the bundle thickness are determined by nucleus concentration and nucleus size, respectively. The atomic force microscopy measurement correlates the elasticity of the actin network, E, with the mesh size, xi, as E approximately xi-1, while the bundle thickness, D dependence of E cannot be described by a simple scaling relation. E approximately D6.5 when D is small and E approximately D0.1 when D is large. Our study on the self-assembly of actin network under asymmetric polycation condition would provide the crucial insight into the organization of biopolymers in polarized condition of cell.     

Numerical integration of the Ostrovsky equation based on its geometric structures

We consider structure preserving numerical schemes for the Ostrovsky equation, which describes gravity waves under the influence of Coriolis force. This equation has two associated invariants: an energy function and the L² norm. It is widely accepted that structure preserving methods such as invariants-preserving and multi-symplectic integrators generally yield qualitatively better numerical results. In this paper we propose five geometric integrators for this equation: energy-preserving and norm-preserving finite difference and Galerkin schemes, and a multi-symplectic integrator based on a newly found multi-symplectic formulation. A numerical comparison of these schemes is provided, which indicates that the energy-preserving finite difference schemes are more advantageous than the other schemes.     

Determination of lead(II) in fly ash leachate using a newly developed simple spectrophotometric method

A new simple method for the spectrophotometric determination of Pb(II) in fly ash leachates was developed. These leachates tend to contain a large amount of Ca(II) and Zn(II); this interferes with spectrophotometric determination of Pb(II) when conventional colorimetric agents are used. A copolymer consisting of protoporphyrin IX disodium salt and acrylamide was synthesized as a colorimetric agent. A measuring reagent containing ethylenediamine-N,N′-dipropionic acid (EDDP) as a masking agent for Zn(II) and an appropriate amount of Ca(II) together with the copolymer was applied to determine Pb(II). The temporal change in the absorption spectrum of the measuring reagent was acquired with a newly developed portable spectrophotometer for this method. The composition of EDDP and Ca(II) in the measuring reagent was optimized to measure leachates contaminated with Ca(II) and Zn(II). The detection limit and relative standard deviation of Pb(II) measured using the optimized method were 0.05 mg L^?1 and 2.3%, respectively. The tolerance limits for Ca(II) and Zn(II) contaminants, where errors of less than 10% were allowed at a concentration of 0.5 mg L^?1 Pb(II), were 4000 and 4 mg L^?1, respectively. The determination of Pb(II) in various samples of actual leachates from incinerator fly ash was examined with this method. The obtained values correlated well with those obtained by flame atomic absorption spectroscopy.     

多孔介质体干燥过程中含水率分布的可视化研究

工业中应用广泛的食品干燥等干燥现象,多是含水多孔介质体的干燥。本文利用可视化实验,研究了含水多孔介质体的干燥现象。并利用实验拍摄的数字图像进行分析和含水率计算,提出干燥过程中含水率分布图像化的方法,并讨论了将此图像化方法应用于含水多孔介质体干燥的可行性。     

Heavy-metal pollution and its state in algae in Kakehashi river and Godani river at the foot of Ogoya mine, Ishikawa Prefecture.

Alga as Achnanthes minutissima among diatoms is a widely adaptable taxon on the state of an aquatic environment. In this study, it was found that diatom had a specific tolerance to heavy metals (Cu, Zn, Pb, and Cd etc.) in river water samples, because the diatom assemblage consisted of almost only Achnanthes minutissima in Kakehashi river and Godani river, which were polluted with waste water from Ogoya copper mine. The relationship between the concentrations of heavy metals (Cu, Zn, Pb and Cd) in river water and the attached substances (algae and silt etc.) and the relative abundances of diatom taxa were investigated in detail. The results indicated that the higher is the concentration of heavy metals in the river environment, the higher is only the relative abundances of Achnanthes minutissima. Thus, the taxon can be used as a bioindicator of heavy metal pollution. The relative rates of toxic chemical forms of copper in algae were 61 - 92% in the attached substances and 49-70% in the sediment on the river bed, respectively. Therefore, it was found that diatom as Achnanthes minutissima had a tolerance to heavy metals in river water, being able to live in such an environment. Since the water treated with calcium hydroxide from the deposition reservoir of Ogoya mine enters in Godani river, the river is polluted by heavy metals (Cu, Zn, Pb and Cd etc.). From the viewpoint of both biological and chemical analyses, Godani river is still polluted with heavy metals, because their concentrations in the river samples were very high. On the other hand, in Kakehashi river, the concentrations of heavy metals were very low and the distributions of some diatoms appeared in an unpolluted Nishimata river were observed. Therefore, Kakehashi river seems to be considerably recovered from heavy-metal pollution after closing the Ogoya mine.