Effect of pH on microbial hydrogen fermentation

The influence of initial pH of the culture medium on hydrogen production was studied using sucrose solution and a mixed microbial flora from a soybean‐meal silo. Hydrogen production was not observed at pH values of 3.0, 11.0 and 12.0 but low production was observed at pH values 5.0 and 5.5. The pH of the experimental mixture decreased rapidly and produced hydrogen gas within 30 h. Methane was not detected at initial pH values between 6.0 and 10.0. The sucrose degradation efficiency increased as the initial pH value increased from 3.0 to 9.0. The maximum sucrose degradation efficiency of 95% was observed at pH 9.0. The maximum specific production yields of hydrogen, VFAs and alcohols were 126.9 cm³ g^?1 sucrose (pH of 9.0), 0.7 gCOD g^?1 sucrose (pH of 8.0) and 128.7 mgCOD g^?1 sucrose (pH of 9.0), respectively. The relationship between the hydrogen ion concentration and the specific hydrogen production rate has been mathematically described. The best kinetic parameters on the specific hydrogen production rate were K_OH = 1.0 × 10^?7 mol dm^?3 and K_H = 1.1 × 10^?4 mol dm^?3 (r² = 0.86). The maximum specific hydrogen production rate was 37.0 cm³ g^?1 VSS h^?1. © 2002 Society of Chemical Industry     

Examination of the role of oxygen in the photografting of methacrylic acid on a polyethylene film with a mixed solvent consisting of water and organic solvents

The photografting of methacrylic acid (MAA) on a linear low‐density polyethylene film (thickness = 30 μm) under air and nitrogen atmospheres was investigated at 60°C in mixed solvents consisting of water and an organic solvent, with xanthone as a photoinitiator. The organic solvents used were acetone, methanol, tetrahydrofuran, and dioxane. A maximum percentage of grafting occurred at a certain concentration of the organic solvent in the mixed solvent. This was observed for the systems under both air and nitrogen. The grafting reaction under air exhibited an induction period, but the rate of grafting after the period was greater than that under nitrogen. The formation of poly(ethylene peroxide)s by photoirradiation seemed to be a factor for the accelerated photografting under air. On the basis of attenuated total reflection infrared spectroscopy and scanning electron microscopy of the grafted film, the MAA‐grafted chains of the sample prepared under air tended to penetrate more deeply inside the film than those of the sample prepared under nitrogen. The resulting grafted films exhibited a pH‐responsive character: the grafted films shrank in an acidic medium but swelled in alkaline medium. This was evaluated from measurements of dimensional changes in the grafted films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 992–998, 2003     

Thermal and flammability properties of a silica–poly(methylmethacrylate) nanocomposite

PMMA, poly(metheylmethacrylate), nanocomposites were made by in situ radical polymerization of MMA, methylmethacrylate, with colloidal silica (ca. 12 nm) to study the effects of nanoscale silica particles on the physical properties and flammability properties of PMMA. Transparent samples resulted and the dispersity of the particles was examined by transmission electron microscopy and atomic force microscopy. The addition of nanosilica particles (13% by mass) did not significantly change the thermal stability, but it made a small improvement in modulus, and it reduced the peak heat release rate roughly 50%. Last, the flame‐retardant mechanism provided by the addition of nanosilica particles in PMMA is discussed. Published 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2072–2078, 2003     

Electro-mechanical coupling in ionic gels

An ionic-polymer–metal-composite film shows electro-mechanical coupling. When the film is bent, electric current is induced. Measurement of the induced current indicates that the current depends on the speed of bending, but the total amount of the charge transferred across the film is independent of the speed, and depends only on the magnitude of the bending. The result indicates that in addition to previously proposed dynamical coupling effect, there is a static electro-mechanical coupling effect. Mathematical model is proposed to describe this phenomena.     

Neuroprotective Effects of Liraglutide for Stroke Model of Rats

The number of diabetes mellitus (DM) patients is increasing, and stroke is deeply associated with DM. Recently, neuroprotective effects of glucagon-like peptide-1 (GLP-1) are reported. In this study, we explored whether liraglutide, a GLP-1 analogue exerts therapeutic effects on a rat stroke model. Wistar rats received occlusion of the middle cerebral artery for 90 min. At one hour after reperfusion, liraglutide or saline was administered intraperitoneally. Modified Bederson’s test was performed at 1 and 24 h and, subsequently, rats were euthanized for histological investigation. Peripheral blood was obtained for measurement of blood glucose level and evaluation of oxidative stress. Brain tissues were collected to evaluate the level of vascular endothelial growth factor (VEGF). The behavioral scores of liraglutide-treated rats were significantly better than those of control rats. Infarct volumes of liraglutide-treated rats at were reduced, compared with those of control rats. The level of derivatives of reactive oxygen metabolite was lower in liraglutide-treated rats. VEGF level of liraglutide-treated rats in the cortex, but not in the striatum significantly increased, compared to that of control rats. In conclusion, this is the first study to demonstrate neuroprotective effects of liraglutide on cerebral ischemia through anti-oxidative effects and VEGF upregulation.     

Growth and microstructure of Ba β-alumina films by laser chemical vapor deposition

Ba β-alumina films were prepared by laser chemical vapor deposition. Mostly single-phase Ba β-alumina films were obtained at 1125–1200 K and for an Al/Ba molar ratio of 12.4–16.6. BaAl₂O₄ and α-Al₂O₃ were codeposited with Ba β-alumina under Ba- and Al-rich conditions, respectively. The Ba β-alumina films consisted of hexagonal grains, and the (1 1 0)-oriented Ba β-alumina films had a fin-like columnar structure. The highest deposition rate reached 120 μm h^?1 at around 1200 K. A thin layer of Ba-rich superstructure was formed on the surface of the (1 1 0)-oriented columnar grains.     

Transparent Lu3NbO7 bodies prepared by reactive spark plasma sintering and their optical and mechanical properties

Transparent lutetium niobate (Lu₃NbO₇) bodies were prepared by reactive spark plasma sintering using Lu₂O₃ and Nb₂O₅ powders. Fully dense Lu₃NbO₇ bodies with density greater than 99.5% of the theoretical were obtained at 1300–1650 °C. The grains steadily grew from 0.1 to 0.6 μm with increasing sintering temperature from 1200 to 1450 °C and significant grain growth from 2.2 to 9.2 μm occurred at 1550–1650 °C. The Lu₃NbO₇ body sintered at 1450 °C showed the highest transmittance of 63% at 550 nm after heat treatment at 850 °C in air for 6 h. Fully dense, submicron-size transparent Lu₃NbO₇ exhibited Vickers hardness of ～13.0 GPa and indentation fracture toughness of 1.0 MPa m^1/2.     

A simple approach to observe non-conductive hydrated materials with FE-SEM: Case study on porous hydroxyapatite green bodies

The purpose of this study is to develop a simple method to observe the surface morphology of non-conductive material in its hydrated condition. Here porous hydroxyapatite (HAp) green body prepared by gelcasting process was considered as a case study, and, the resultant body was subsequently treated with hydrophilic ionic liquid (IL). The surface morphology and the pore structure of the IL-treated porous HAp green body were successfully observed even in hydrated condition without any charging using field emission scanning electron microscope (FE-SEM). Results showed that the pore diameter from 300 to 600 μm in as-prepared green body was reduced to 100–300 μm in the sample sintered at 1000 °C. Raman results showed that the IL forms weak hydrogen bond with water molecules within the sample and, that prevents from drying in vacuum condition. In addition, the IL acts as a conducting media for HAp ceramics to be observed under FE-SEM.     

X-ray studies of multiple melting behavior of poly(butylene-2,6-naphthalate)

Multiple melting behavior of poly(butylene-2,6-naphthalate) (PBN) was studied with X-ray analysis and differential scanning calorimetry (DSC). Double endothermic peaks L and H attributed to the α-form crystal modification, a small peak attributed to the β-form crystal modification, and a new shoulder peak S at a lower temperature of peak H appeared in the DSC melting curves. Wide-angle X-ray diffraction patterns of the samples isothermally crystallized at 200 and 220 °C were obtained at a heating rate of 1 K min⁻¹, successively. In this heating process, change of crystal structure and increase of quantity of the β-form crystallites could not be observed up to the final melting. With increasing temperature, the diffraction intensity decreased gradually and then increased distinctly before a steep decrease due to the final melting. The X-ray analysis clearly proved the melt-recrystallization during heating. The β-form crystal modification was formed during slow heating process in the high temperature region.     

Structural Study on PbO–SiO2 Glasses by X-Ray and Neutron Diffraction and 29Si MAS NMR Measurements

Structure of x PbO–(100− x )SiO₂ ( x =25–89) glasses has been investigated by means of the X-ray and neutron diffraction and ²⁹Si MAS NMR measurements. In the radial distribution functions of all the glasses, the Pb–O correlation was observed at 0.23 nm, indicating that the PbO₃ trigonal pyramids units do exist in the whole glass forming composition range. Furthermore the existence of the first Pb–Pb correlation at ∼0.385 nm in the whole composition range suggests that the basic structural unit is considered to be a Pb₂O₄ unit, which consists of the edge-shared PbO₃ trigonal pyramids. These results strongly imply that the Pb₂O₄ units participate in the glass network constructed by SiO₄ tetrahedra even at low PbO content. Differing from other lead-containing glass systems, these structural characteristics of Pb ions in the PbO–SiO₂ glass system are responsible for the extremely wide glass-forming region.