Self-organization in an ecosystem

An ecosystem, especially a food web, is essentially characterized as a many-body system in which the members interact with each other under the limitations of the energy and resources. We introduce a coevolutional population dynamics model for food webs which contains energy-conserving interactions, energy dissipation, and rules for changing the degrees of freedom (extinction and mutation). In this model, the diversity of the system increases spontaneously. The statistical properties of the system, such as the distribution of the life time of the species, are also discussed. This work was presented, in part, at the Sixth International Symposium on Artificial Life and Robotics, Tokyo, Japan, January 15–17, 2001     

Superconducting State of the Two-Dimensional Superconductor α-(ET)2NH4Hg(SCN)4 Under the Magnetic Field Parallel to the Conducting Plane

The resistive transition to the superconducting (SC) state in -(ET)₂NH₄Hg(SCN)₄ was studied under magnetic fields applied parallel to the conducting plane. The SC state is divided into three regions: (1) temperature-dependent resistive region, (2) zero-resistive region, and (3) temperature-independent resistive region. We observed twofold symmetry in the resistance under an in-plane magnetic field near the midpoint of the SC transition, which indicates that the upper critical field ₀ H _c2 has the same twofold symmetry. This in-plane anisotropy can be ascribed to the crystal structure.     

Production and some properties of salt-tolerant beta-xylosidases from a shoyu koji mold, Aspergillus oryzae in solid and liquid cultures

Beta-xylosidase production from a shoyu (soy sauce) koji mold, Aspergillus oryzae HL15, cultured in solid and liquid media was examined and some properties of the enzymes were studied. Three beta-xylosidases (Xy11, Xy12 and Xy13) were easily extracted with 0.5% NaCl from a solid medium and purified homogeneously on SDS-PAGE by chromatography. On the other hand, in a liquid medium, A. oryzae HL15 produced mainly cell-wall-bound beta-xylosidases which could not be extracted with 0.5% NaCl or any detergent. Cell-wall-bound beta-xylosidases, Xy11-CB and Xy12-CB, were liberated by digestion of mycelia with Yatalase and purified to a homogeneous state on SDS-PAGE by HPLC column chromatography. Four beta-xylosidases (Xy11, Xy12, Xy11-CB and Xy12-CB) exhibited not only high activity at high NaCl concentrations, but also similar properties; on the other hand, Xy13 differed in terms of thermostability and halophilic properties. The salt tolerance of beta-xylosidases in A. oryzae suggests that these enzymes are highly active and involved in releasing xylose in shoyu moromi mash.     

Analysis of Field Orientation Control of Current Source Inverter Drive Induction Motor Systems

The field orientation control of current source inverter (CSI) drive induction motor (IM) systems has been known to give an induction motor dc motorlike characteristics. As a result of an analysis, the characteristic of these systems does not necessarily coincide with that of dc motor systems, especially with light loads. The result of the analysis is verified by experiments.     

Free-Standing Molecularly Thin Amorphous Silica Nanosheets (Small 22/2023)

Recent progress in 2D materials has initiated new fields of molecularly thin amorphous materials with mysterious properties and structures. However, designed synthesis of molecularly thin amorphous silica still remains a challenge; whether free-standing molecularly thin amorphous silica nanosheets can exist is unclear. Here, this issue is addressed by using a new chemical protocol; solid-state surfactant lamellae with ordered alkyl-chain arrangements can serve as superior templates guiding free-standing amorphous silica nanosheets. Simple sonication of the lamellar hybrids allows exfoliation into monolayer amorphous silica nanosheets with 0.9 nm thickness. In addition, the nanosheets show the distinctive feature of high colloidal stability that enables atomic layer engineering of silica nanocoatings and dielectric nanofilms. The approach may shed new light on the properties and applications of old silica.     

Relative permittivity and conductivity of water‐treed region in XLPE estimated by an equivalent circuit

By dividing a water‐treed XLPE sheet sample of 1 mm thickness into a nondegraded region and a water‐treed one, relative permittivity and AC conductivity σ_AC2 of the water‐treed region have been estimated using an equivalent circuit. The variation of and σ_AC2 with the length r of the water‐treed region has been discussed based on the Sillars model. It was concluded that the volume fraction of water in the water‐treed layer is in the range from 0.5% to 1.5% for the most‐degraded XLPE sheet, which depends on the ratio of axes of spheroids to which water‐filled voids and channels are compared. It was also concluded that the AC conductivity of water in the water‐treed region ranges from 3 × 10^?3 S/m to 2 × 10^?2 S/m. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 7–14, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10332     

Therapeutic effects of phytosterols and phytostanols in cholesterolemia

Plant sterol and stanol esters are called "functional" compounds due to their hypocholesterolemic properties. The objective of this review is to update recent findings concerning the effect of phytosterols in the blood cholesterol, emphasizing the results from experimental and human studies. The hypocholesterolemic effect is observed with the intake of 2.5g/day of phytosterols or phytostanols. Daily intake, usually of stanols, for 4 weeks has shown to to be effective in lowering blood total- as well as LDL-cholesterol by about 10%. The mechanism of action in lowering blood cholesterol comes from their structural similarity to cholesterol, hence they act by competing with cholesterol at the luminal absorption site. The adverse effects of a high intake of phytosterols and phytostanols are the lower absorption of some liposoluble vitamins and antioxidants.     

Properties of column spacers on a flexible color filter using a roll‐to‐roll process

Abstract— Column spacers were manufactured by a roll‐to‐roll process for a flexible plastic substrate and an LCD prototype was demonstrated for the first time. The purpose of this paper is to obtain a stable cell gap for plastic LCDs by designing the column spacers. The optimum condition was derived for the properties of the column spacers parameters, such as the cross section, density, and hardness. As a result, we could determine the optimum elastic modulus of the column spacers needed in order to precisely maintain the cell gap of the LCD as well as that of conventional glass plates, resulting in a uniform display luminance.     

Three-way two-dimensional alternating finite automata with rotated inputs

The authors have introduced an automaton on a two-dimensional tape, which decides acceptance or rejection of an input tape by scanning the tape from various sides by three-way (deterministic and nondeterministic) finite automata, and have investigated the accepting powers. This paper continues the investigation of this type of automata, which consists of four three-way two-dimensional alternating finite automata (tr2-afa’s). We first investigate a relationship between the accepting powers of ∨-type automata (obtained by combining tr2-afa’s in ‘or’ fashion) and ∧-type automata (obtained by combining tr2-afa’s in ‘and’ fashion), and show that they are incomparable. Then, we investigate a hierarchy of the accepting powers based on the number of tr2-afa’s combined. Finally, we briefly describe a relationship between the accepting powers of automata obtained by combining three-way two-dimensional nondeterministic and alternating finite automata.     

Carbon nanotube scanning tunneling microscopy tips for chemically selective imaging

Carboxyl-terminated single-walled carbon nanotubes (SWNTs) were successfully immobilized from solution phases onto the apexes of gold tips for scanning tunneling microscopy (STM). Gold STM tips were first modified with self-assembled monolayers of 4-mercaptobenzoic acid, and its carboxyl groups were used to anchor carboxylated SWNTs through Zn2+ ion-bridged coordination. These SWNT tips gave high-resolution STM images of a diether monolayer formed on the graphite surface. In addition and more importantly, the ether oxygens of the sample molecules were selectively observed as bright spots with the SWNT tips with significantly high reproducibility, which is due to the facilitation of electron tunneling through hydrogen bond interactions between the ether oxygens and carboxyl groups at the end of the SWNT tips.