The role of rolling friction in granular packing

In order to study the effects of the rolling friction of the particles on granular packing, we present a detailed analysis of circular disk assemblies with the rolling friction under macroscopic one-dimensional compression. The rolling friction of the particles produces a resisting moment to the rolling at each contact. A series of 2-D DEM simulations are performed with various values for the rolling friction parameter. We focus on several macroscopic and microstructural properties of granular media and analyze them as a functions of the rolling friction. From these results, we show that the rolling resistance, which results from the rolling friction of the particles, contributes to the inhibition of the rearrangement of the particles and increases the magnitude of the fabric anisotropy under packing. In addition, from both microscopic and macroscopic points of view, we describe that the stress state in a granular packing can vary considerably depending on the rolling resistance.     

Temporal resolution of the skin impedance measurement in frequency-domain method

The temporal-resolution of the frequency-domain method for the identification of the impedance locus depends on the basis frequency used in the current waveform construction, i.e., the higher basis frequency provides the better temporal resolution. The impedance locus can be characterized by the impedance parameters Z0, beta, and taum. The frequency distribution of limited number of data in the impedance locus would affect the accuracy of the estimated impedance parameters. Therefore, we investigated the relationship between the estimation accuracy of the impedance parameters and the frequency coverage of the impedance locus in relatively low to high impedance conditions (dc impedance Z0= 51 k ohms - 45 M ohms). As the basis frequency, 100 Hz was enough for the usual impedance with Z0 less than 203 k ohms. On the other hand, 10 Hz and 1 Hz were required for the medium-level (Z0 = 517 k ohms), and high-level (Z0 = 45 M ohms) impedance, respectively. The required basis frequency, accordingly the temporal resolution, depended much on the central relaxation time taum which affects the frequency distribution on the impedance locus. The results of this study are expected to serve as the reference of the frequency selection in the frequency-domain analysis of the skin impedance.     

A novel polysaccharide involved in the pellicle formation of Acetobacter aceti

Acetobacter aceti IFO 3284 has been shown to have two types of strains: one forms a smooth-surfaced colony (S strain) and the other forms a rough-surfaced colony (R strain) (Matsushita et al., 1992). In this study, both S and R strains were isolated and characterized. The S strain grew well in submerged culture but very poorly in static culture. In contrast, the R strain grew well in static culture by floating on the surface of the culture medium, as well as in shaking submerged culture. Scanning electron microscopy revealed that the R strain was covered by some amorphous materials that were not seen in the S strain. The R strain produced 5-fold higher levels of sugars related to polysaccharides responsible for pellicle formation than the S strain did. Unlike cellulose of Acetobacter xylinum, the polysaccharides of the R strain were cellulase-resistant and alkaline-sensitive. The polysaccharides were not secreted into the culture medium, and more than 90% of them were retained in the membrane fraction when the cells were disrupted under mild conditions by lysozyme treatment. Furthermore, the polysaccharides were shown to be mainly attached to the outer membrane when separated. After solubilization with beta-octylglucoside, the membrane-attached polysaccharides were purified by several steps including enzyme treatment, column chromatography and alcohol precipitation. The purified polysaccharide was estimated to have an apparent molecular mass of 700-kDa based on Sephacryl S-500 column chromatography, and to be composed of two monosaccharides, glucose and rhamnose, at an approximately equimolar ratio. Thus, in this study, we clarified that the A. aceti R strain produced a polysaccharide associated with the flotation of the cells on the medium surface, like A. xylinum, and that the polysaccharide was a novel one consisting of glucose and rhamnose.     

Glass Substrates for OLED Lighting with High Out-coupling Efficiency

Glass substrates which realize high out-coupling efficiency OLEDs （organic light emitting diodes） were developed. A scattering layer whose matrix was made of high refractive index glass was formed on a glass substrate, and pores in the glass matrix work as scattering centers. The out-coupling efficiency of an OLED using this substrate is 1.8 times higher compared with an OLED using an untreated glass substrate. Furthermore angular dependency of the color and color variation between panels can be successfully suppressed.     

Effects of fly ash in composites fabricated by injection molding

In this study, the effects of fly ash in composites fabricated by injection molding are examined. Taguchi design of experiment was first utilized to estimate the effects different injection molding conditions and content ratios of fly ash have on a linear low‐density polyethylene (LLDPE)‐fly ash composite. The results reveal that the content of fly ash is highly significant and contributive to the shrinkage ratio and bending strength. For these reasons, LLDPE and polypropylene (PP) composites with different size particles of fly ash were fabricated and the mechanical properties were investigated. The particle size was changed by grinding fly ash with a planetarium ball mill. The shrinkage ratio, bending strength and flexural modulus of LLDPE composites containing raw fly ash were found to improve. The shrinkage ratio and flexural modulus of PP composites containing ground fly ash were also found to improve. Homogenization analysis using the finite element method was then used to calculate the Von Mises stress distributions and homogenized elastic matrix of PP composites containing ground fly ash. The homogenized elastic matrix was used to validate the experimental flexural modulus. The results show that the homogenized elastic matrix is in good agreement with the experimental flexural modulus. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Purification and characterisation of two extracellular acid proteinases from Monascus pilosus

Genus Monascus is one of the most important microorganisms in the fermentation industry in Asia. However, only a little attention has been paid to the proteinases produced by this fungus and their role in the fermentation process. The main objective of this study was to purify and characterise acid proteinases produced by Monascus pilosus. Two acid proteinases (MpiAP1 and MpiAP2) were purified to homogeneity. Both purified enzymes, MpiAP1 and MpiAP2, were monomeric structures with molecular masses of around 43 and 58 kDa, respectively. The former was an acidic non-glycoprotein, whereas the latter was an acidic glycoprotein with 27% carbohydrate content. Although amino-terminal amino acid sequence analysis of both enzymes (MpiAP1 and MpiAP2) of 20 amino acid length showed over 90% similarity, their amino-terminal amino acids were different from each other. Both enzymes were optimally active at 55 °C and at pH 2.5–3.0 against casein or human haemoglobin. The T_1/2 values of MpiAP1 and MpiAP2 were 65 and 70 °C, respectively. Both of the enzymes were completely inhibited by pepstatin A, and markedly by SDS. MoO₃ also showed a partial inhibition of both enzymes. Milk casein and haemoglobin were good substrates for these enzymes. Eleven cleavages were detected using the oxidised insulin B-chain as a peptide for the proteolytic specificity test of MpiAP1, while seven cleavages were detected for MpiAP2.     

Female Sex Pheromone of a Carpenter Moth, Cossus insularis (Lepidoptera: Cossidae)

This study describes the identification of a sex pheromone component of a cossid moth, Cossus insularis. Coupled gas chromatographic–electroantennographic detection (GC–EAD) analysis of solid-phase microextraction (SPME) collections of volatiles released by live female moths showed that two compounds elicited EAG responses from the antennae of male moths. These compounds were identified as (E)-3-tetradecenyl acetate (E3-14:Ac) and (Z)-3-tetradecenyl acetate (Z3-14:Ac) by mass spectral analysis and retention index comparisons with synthetic standards. The ratio of E3-14:Ac and Z3-14:Ac was 95:5 in the effluvia of a female. In field bioassays, sticky traps baited with blends of E3-14:Ac and Z3-14:Ac showed that E3-14:Ac is an essential component of the pheromone. However, the role of Z3-14:Ac is unclear, because E3-14:Ac as a single component was as attractive to male moths as blends of E3-14:Ac and Z3-14:Ac, including the 95:5 blend released by live female moths.     

Formaldehyde elimination with formaldehyde and formate oxidase in membrane of acetic acid bacteria

Formaldehyde elimination was successfully carried out with Acetobacter sp. SKU 14, having strong formaldehyde-oxidizing activity in the cytoplasmic membrane. Formaldehyde was decomposed via formate to carbon dioxide by formaldehyde- and formate-oxidizing activities. A resting-cell suspension of the organism was more convenient for practical purposes than the isolated membrane fraction. In Gluconobacter suboxydans IFO 12528, formaldehyde elimination was not so prominent when compared with that in Acetobacter sp. SKU 14.