Phase equilibria of quasi-ternary systems consisting of multicomponent polymers 1 and 2 in a single solvent. II. Cloud point curve

Theoretical equations and a calculation method giving cloud point curve (CPC) for a multicomponent polymer 1/multicomponent polymer 2/single solvent system (i.e. quasi-ternary system) were derived on the basis of the Flory-Huggins solution theory. The systematic calculations based on this method were carried out to examine the effects on CPC of the type of molecular weight distribution, the polydispersity and the weight-average degree of polymerisation of the two original polymers, and three thermodynamic interaction parameters between solvent-polymer 1 (X₀₁), solvent-polymer 2 (X₀₂) and polymer 1-polymer 2 (X₁₂). The shape of CPC sensitively depends on the polydispersity of the original polymer and, with an increase in polydispersity, the immiscibility region becomes wider.     

Periodical Oscillation Phenomena Observed in Salt-Water Oscillator Experiments under Small Gravity Conditions

We examined periodical oscillation phenomena that were observed during salt-water oscillator experiments under a small gravity condition. This condition was realized by situating a lower-density gadolinium chloride (GdCl ₃) aqueous solution on a higher-density sodium chloride (NaCl) aqueous solution and applying a downward magnetic force. The GdCl ₃ solution concentration was 0.15 mol/kg (density ρ=1.03×10³ kg/m ³), and the NaCl concentration was varied to (A) 4.35 mol/kg (ρ=1.15×10³ kg/m ³), (B) 3.79 mol/kg (ρ=1.12×10³ kg/m ³), and (C) 2.49 mol/kg (ρ= 1.09×10 ³ kg/m ³). The magnitude of magnetic flux density was varied from 0 to 4.00 T. As the magnetic flux density grew larger, the GdCl ₃ solution was pulled downward by the magnetic force, and upward and downward flows were generated simultaneously at the orifice. These flows were accompanied by a periodical, locally thickened part. The thickened part was only observed when the magnetic force magnitude was small in cases (A) and (B). This flow pattern was not observed in case (C), in which a conventional salt-water oscillation was induced instead (C). In this paper we discuss new experimental results in which the oscillation cycles in cases (A) and (B) are strongly associated with the magnitude of the magnetic force and the density difference in the biphase solutions.     

Specific determination of bromate in bread by ion chromatography with ICP-MS

A sensitive method for detecting bromate in bread by ion chromatography with inductively-coupled plasma mass spectrometry (IC/ICP-MS) was developed. Bromate was extracted from bread with water. The clean-up procedure included a 0.2 micron filter, a C18 cartridge for defatting, a silver cartridge to remove halogen anions, a centrifugal ultrafiltration unit to remove proteins, and a cation-exchange cartridge to remove silver ions. A 500 microL sample solution was applied to IC/ICP-MS. The detection limit and the quantitation limit of bromate in the solution were 0.3 ng/mL and 1.0 ng/mL, expressed as HBrO3, respectively, which corresponded to 2 ng/g and 5 ng/g, respectively, in bread. Recovery of bromate was about 90%, and the CV was about 2%. Based on the detection limit in solution and recovery from bread, the detection limit of bromate in bread was estimated to be 2 ng/g.     

Methane production from steam-exploded bamboo

To convert unutilized plant biomass into a useful energy source, methane production from bamboo was investigated using a steam explosion pretreatment. Methane could not be produced from raw bamboo but methane production was enhanced by steam explosion. The maximum amount of methane produced, i.e., about 215 ml, was obtained from 1 g of exploded bamboo at a steam pressure of 3.53 MPa and a steaming time of 5 min. A negative correlation between the amount of methane produced and the amount of Klason lignin was observed in the methane fermentation of steam-exploded bamboo.     

Microbial analyses by fluorescence in situ hybridization of well-settled granular sludge in brewery wastewater treatment plants

The characteristics of granular sludge from full-scale upflow anaerobic sludge blanket reactors used for the treatment of brewery wastewater were investigated. Fluorescence in situ hybridization (FISH) analyses of settled granules from a reactor that had been treating brewery wastewater stably at COD removal rates of over 90% for more than 6 months showed that a methanogen of the genus Methanosaeta was predominant near the granule surface and that Bacteria were not abundant. The center of the granules was composed of dead or resting cells, or both, which were used as a support for active archaeal and bacterial cells near the surface. Periodic analysis of granules from full-scale plants showed that granules containing methanogens deep within them tended to float. Granules with a Bacteria layer on the surface also tended to float. On the basis of these findings, well-settled granules are considered to have methanogens that develop near the granule surface so that the gases generated during methane fermentation are readily released.     

Change in molecular weight of hyaluronic acid during measurement with a cone-plate rotational viscometer

It was shown using a cone-plate rotational viscometer that the apparent viscosity of a dilute aqueous solution of sodium hyaluronate decreased gradually during the measurement. Hyaluronic acid (HA) forms a characteristic network by entanglements coupling, so two hypotheses could be postulated from the reduction of viscosity due to shearing stress. One was that disentanglement of the temporary network occurred, and the other was that scission of HA chains was responsible. In this study, the reason for the reduction in viscosity was clarified using high-performance gel permeation chromatography with low-angle laser light scattering. It was thus demonstrated that chain scission occurred during the viscometric measurement. On the assumption that the HA degradation was caused by shearing stress, the effects of shearing rate, the initial molecular weight, salt, and polymer concentrations of samples were investigated. High molecular weight HA chains were preferably severed. From the change in polydispersity of the samples it was inferred that due to the viscoelasticity of HA solution scission behavior would differ, depending on the shearing rate. Also, the salt and polymer concentrations were found to exert large influences on the degradation. Thus, it was concluded that the scission rate was related to the expansion of HA molecules in solution. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2199–2206, 1998