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.     

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.     

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.     

Mean field with tensor force and shell structure of exotic nuclei

The tensor force is implemented into the mean-field model so that the evolution of nuclear shells can be described for exotic nuclei as well as stable ones. Besides the tensor-force part simulating the meson exchange, the model is an extension of the successful Gogny model. One of the major issues of rare-isotope beam physics is a reduced spin-orbit splitting in neutron-rich exotic nuclei. It will be shown that the effect of the tensor force on this splitting is larger than or about equal to the one due to the neutron skin. We will present predictions for stable and exotic nuclei with comparisons to conventional results and experimental data.     

Statistical simulation based on right skewed distributions

Statistical simulations in medical and biological research are usually conducted with normal random numbers. However, in many cases, the distributions of real data in medical fields are usually right skewed. The conclusions led by simulations with the misspecified model might be misleading because of a gap between real data’s distribution and theoretical one. In this paper, we provide the simulation procedure for right skewed data based on reparameterized, easily interpretable parameters of the Box–Cox transformation model which includes multivariate distributions and regression models. We also show that the provided procedure is widely applicable to real world based on laboratory data, and then we provide parameter vector sets obtained by reparameterized parameter estimates that would cover almost all situations in which the distributions of data were right skewed and unimodal.     

Module Assembly for Designing Multivalent Mid‐Sized Inhibitors of Protein‐Protein Interactions

Developing clinically relevant synthetic agents that are capable of disrupting protein‐protein interactions (PPIs) is now a major goal of scientific research. In an effort to explore new methodologies that are applicable to the design of synthetic PPI inhibitors, we examined a strategy based on the assembly of small module compounds to create multivalent mid‐sized agents. This personal account describes three particular approaches based on module assembly: metal‐chelating‐based ligand assembly, covalent chemical ligation templated by a targeted protein, and bivalent inhibitor design for simultaneous targeting of the active pocket and protein surface. These strategies were shown to be useful for synthesizing minimally sized synthetic agents for targeting PPIs and may enable development of agents that are applicable to inhibition of intracellular PPIs.     

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.