Application of fuzzy C‐means for understanding water quality in Lake Hachiroko,Japan

This letter reports on the water quality conditions of Lake Hachiroko estimated by fuzzy c‐means clustering (FCM). Growth of blue‐green algae in the summer significantly degrades the water quality of the lake. On the basis of experimental results using ALOS AVNIR data from the months of August and September, and a comparison with results obtained from fuzzy regression analysis, it is found that the fuzzy c‐means technique is effective in determining the water surface conditions of the lake, especially in relation to blue‐green algae growth. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Survival and growth of enterotoxin-positive and enterotoxin-negative Clostridium perfringens in laboratory media

The survival and growth characteristics of enterotoxin-positive and enterotoxin-negative Clostridium perfringens were compared. Spores of C. perfringens were heated and incubated in laboratory media to simulate the cooking and inadequate storage of cooked food. In our experiment, enterotoxin-positive and enterotoxin-negative spores were heated and incubated individually and it was found that spores of enterotoxin-positive strains were more heat-resistant than spores of the enterotoxin-negative strains. In another experiment, cocktails of enterotoxin-positive and enterotoxin-negative spores were heated and incubated. At the time of inoculation, the ratio of enterotoxin-positive spores to enterotoxin-negative spores was about 1:100. In the case of high-temperature heat treatment, the number of enterotoxin-negative spores decreased to below that of enterotoxin-positive spores after heating, and enterotoxin-positive strains grew to high levels during incubation. In the case of low-temperature heat treatment, the number of enterotoxin-negative spores remained almost unchanged after heating and enterotoxin-positive strains did not grow to high CFU levels during incubation.     

In vitro osteogenic differentiation of HOS cells on two types of collagen gels

HOS cell is a model strain of human osteoblasts derived from human osteosarcoma. We cultured the HOS cells on both the conventional collagen gel (neutral gel), and the gamma-crosslinked collagen gel without collagen fibrils (acidic gel). The shape of HOS cells on the neutral gel was similar to that on the culture dish. However, HOS cells on acidic gel had an elongated shape and attached each other to form a mesh-like pattern. The cells attached to the surface of both gels but scarcely penetrated their depths. We measured the biochemical markers for osteogenic differentiation in the HOS cells cultured on both the neutral gel and the acidic gel. The expressions of alkaline phosphatase and osteocalcin were detected in the HOS cells on both types of collagen gel. Deposition of the calcium also occurred on both gels although it was higher in the neutral gel than the acidic one. These results indicate the importance of collagen for the differentiation of HOS cells, but it is not dependent on the molecular structure (fibril formation) of collagen.     

Automatic composition and simulation system for ballet sequences

We have developed an automatic composition system for ballet choreographies by using 3DCG animation. Our goal is to develop useful tools in dance education such as a creation-support system for ballet teachers and a self-study system for students. The algorithm for automatic composition was integrated to create utilitarian choreographies. As a result of an evaluation test, we verified that the created choreographies had a possibility to be used in the actual lessons. This system is valuable for online virtual dance experimentation and exploration by teachers and choreographers involved in creative practices, improvisation, creative movement, or dance composition.     

Improved method for determining bisphenol A in polycarbonate products without using dichloromethane

An improved method for determination of bisphenol A (BPA), phenol (PH), p-tert-butylphenol (PTBP) and diphenylcarbonate (DPC) in polycarbonate products was developed without using the hazardous solvent dichloromethane. Polycarbonate samples were ground to powder or cut into small pieces, and 0.5 g was soaked in 5 mL of acetonitrile for 24 hours at 40 degrees C. The test solution was then filtered and subjected to HPLC analysis. The proposed method was evaluated by comparison of the results with those of the standard method for 14 polycarbonate products. Extraction ratios (average values obtained by the present method/average values obtained by the standard method) of BPA, PH, PTBP and DPC were 0.89-1.19, 0.89-1.14, 0.94-1.30 and 1.08-1.11, respectively. While 120 mL/sample of organic solvent is required in the standard method, only 5 mL/sample of acetonitrile was used in our new method.     

Fire resistance test for fire protection materials with high water content

It is known that moist fire protection materials show good fire resistance characteristics. For this reason, these materials are usually made of mixtures of cement mortar and high water content materials such as silica gels or moist perlites. The latent heat of water plays an important role in the resistance of heat propagation in these materials. In this study, a fire resistance test of a material with high water content is conducted and the temperature response of the test is obtained. Also, the water content of the test materials is measured. The test material consists of a mixture of perlite mortar and gel. The gel absorbs the aqueous solution of calcium chloride, which serves as a water storage mechanism. The numerical predictions to simulate the fire resistance test were conducted and the results were compared with the experimentally obtained temperature responses.     

Overexpression of the robA gene increases organic solvent tolerance and multiple antibiotic and heavy metal ion resistance in Escherichia coli

Escherichia coli K-12 OST3410 was isolated previously as a stable cyclohexane-tolerant mutant derived from cyclohexane-sensitive strain JA300. A plasmid which provides cyclohexane tolerance to strain JA300 was isolated from the OST3410 genomic library. Subcloning and sequence analysis showed that the plasmid contained the robA gene, whose gene product was reported to bind specifically to the right border of oriC. We observed that the robA gene on the multicopy plasmid generally increased the organic solvent tolerance of several E. coli strains. We also observed an increase in the organic solvent tolerance of JA300 carrying the lac-robA fusion gene on a low-copy plasmid by isopropyl-beta-D-thiogalactopyranoside induction. Strain JA300 carrying the multicopy robA plasmid also showed an increase in resistance to a number of unrelated antibiotics and heavy metal ions, and the spectrum of resistance was significantly similar to that of the soxS-overexpressing strain.     

Determination of genotoxic phenylhydrazine agaritine in mushrooms using liquid chromatography-electrospray ionization tandem mass spectrometry

A new method with good sensitivity and specificity for detecting and quantifying genotoxic hydrazines, agaritine and 4-(hydroxymethyl)phenylhydrazine (HMPH), was developed using liquid chromatography-electrospray tandem mass spectrometry (MS). Synthetic agaritine and HMPH were structurally assigned by ¹H-, ¹³C- and two-dimensional nuclear magnetic resonance (NMR) analysis (HMBC and HMQC), high-resolution fast-atom bombardment (HR-FAB) MS and time of flight (TOF) MS. The polar molecule agaritine was separated on an ODS column using 0.01% AcOH-MeOH (99:1, v/v) as an eluent with a simple solid-phase extraction cleanup. There were no interference peaks for any of the mushrooms. Agaricus spp. contained 1247 and 2017 µg g^-1 agaritine. Other species of mushroom had no agaritine. Recoveries of agaritine from spiked mushroom samples were 60.3-114%. Intra-day precision values were 5.5 and 4.2%, and the inter-day precision values were acceptable (15.0 and 23.0%), as agaritine is unstable. The limit of quantification was 0.003 µg g^-1. Even a trace amount of agaritine in mushrooms can, therefore, be determined using this method. We also directly analysed HMPH, an active free hydrazine form of genotoxic agaritine, and obtained direct evidence of its absence from mushrooms. A precursor ion scan confirmed that agaritine derivatives, which could exert similar toxicity, were absent. The results indicate that this specific and sensitive analytical method for detecting and quantifying agaritine and its derivatives could help evaluate the risk of mushroom hydrazines to humans.     

Cationic comb-type copolymers for boosting DNA-fueled nanomachines

For the better applications and developments of DNA nanomachines, their responding kinetics, output, and sequence-selectivity need to be improved. Furthermore, the DNA nanomachines currently have several limitations in operating conditions. Here we show that a simple addition of a cationic comb-type copolymer, poly(l-lysine)-graft-dextran, produces the robust and quick responses of DNA nanomachines under moderate conditions including physiologically relevant conditions even at very low strand concentrations (nanomoles per liter range) through hybrid stabilization and DNA strand exchange acceleration.