Sintering mechanism of hydroxyapatite by addition of lithium phosphate

The sintering mechanism of hydroxyapatite (HAp) by addition of lithium phosphate (Li₃PO₄) has been investigated. Using the X-ray diffraction method, HAp was confirmed to decompose into -Ca₃(PO₄)₂ (-TCP) by addition of Li₃PO₄. The measurement of shrinkage rate by the isothermal firing made it clear that the densification process at the initial stage of sintering took place in the presence of liquid phase. Furthermore, the examination of the phase diagram on the binary system -TCP-Li₃PO₄ revealed that there was an eutectic point at 1010°C in the composition of 60 wt% Li₃PO₄. From these evidences, we concluded that -TCP produced by the decomposition of a part of HAp has formed the liquid phase by reacting with Li₃PO₄ above 1010°C, and that this liquid phase has largely promoted the densification by the rearrangement of HAp particles at the initial stage of sintering.     

Charge behavior in flowing oil in oil/ pressboard insulation system by electro-optic field measurement

The electrical insulation structure of most power transformers is a combination of insulating oil and solid materials. One of the crucial problems we face in transformer operation is flow electrification, which occurs at a flowing oil/solid material interface. Thus, for the transformer insulation design, we need to clarify the now electrification phenomena. In this paper, we measured the electric field strength in an oil/pressboard composite insulation system using an electro-optic method of the Kerr effect. We obtained the time variation of electric field distribution in both flowing uncharged and charged oil. It is notable that we could quantitatively clarify the electric field distortion in flowing charged oil by flow electrification. Furthermore, we measured the leakage current from divided electrodes and derived a charge density distribution along the flow direction. Finally, we quantitatively discussed the electric field distribution and the charge behavior from the measurement results.     

A study of protein A-gold resolution for immunoelectron microscopy

For the purpose of investigating a topographical correlation between antigen molecules and protein A-gold(PAG) particles which localized as an immunocytochemical probe, the simplest model on a localization pattern of antigen molecules, which were arranged two-dimensionally on a plane surface of the resin, was used. Ultrathin sections of a G-actin layer, which was adsorbed on epoxy resin and was re-embedded subsequently in JB-4 resin, was stained indirectly with rabbit anti-actin antibody and subsequently by PAG. From this immunoelectron microscopy, a histogram (relative frequency, denoted by y vs. relative length, denoted by x) was obtained using a computer-assisted method. For this histogram, a fitting curve was calculated by a least squares optimization and three parameters (H, U, and W) of the curve which could be useful for a study on the topographical organization of antigen molecules were estimated. Parameter H (maximum y of the curve) would reflect the maximum amount of epitopes at x = U. Half width W, which is the width of the curve at y = H/2, would reflect a breath of epitope masses. This fitting curve was separated into two overlapping curves whose Ws were different from each other. The one constituent curve of which value W was smaller than the other was regarded as a unit curve and the other constituent curve could be resolved into many unit curves whose W values are the same. From these unit curves, the resolution power of the immunoelectron microscopy, using a post-embedding procedure of ultrathin sections, was estimated as 58–66 A°.     

The effect of permanent dipole moments of adsorbates upon I-V characteristics of a bilayer tunneling junction between self-assembled monolayers on an Au(111) substrate and a gold tip

It is important to understand an electronic property of an interface between an organic material and a metal electrode. In the present work, we measured current-voltage (I-V) curves of self-assembled monolayers (SAMs) on Au(111) using a conducting atomic force microscope (AFM) with chemically modified Au-coated AFM tips. This contact resulted in a bilayer junction between the Au(111) substrate covered with one SAM and the Au-coated tip with the other SAM. An alkanethiol (octanethiol) and benzenemethanethiols with various terminal groups (-H, -CH(3), -Cl, -CF(3)) were used as the adsorbates. The shapes of the I-V curves depended on the terminal groups. This phenomenon was attributed to the change in the work function of gold due to different permanent dipole moments of the terminal groups.     

‘Lipase and protease production of dairy Penicillium sp. on milk‐protein‐based solid substrates’

The lipolytic and proteolytic activity of Penicillium camemberti PC TT033 and Penicillium roqueforti PR G3, cultured on the whey solids or simulated cheese media, were compared under several pH reaction conditions. Lipolytic activity was higher when both strains had been cultured on the whey medium than on the simulated cheese medium, whereas proteolytic activity was less influenced by the culture medium. The relationship between the reaction pH and these enzyme activities was dependent on the culture medium, which suggested that the expression level and balance of isozyme rely on the culture substrate.     

Effect of annealing on photovoltaic properties and microstructure of conventional and inverted organic solar cells using active bilayer based on liquid‐crystal semiconducting polymer and fullerene

Conventional and inverted organic solar cells of poly[9,9‐dioctyl‐fluorene‐co‐bithiophene] (F8T2) as liquid‐crystal semiconducting polymer and fullerene as electron acceptor were fabricated and characterized. An effect of thermal treatment of the films on annealing condition near glass transition was investigated for tuning optimization and improving the photovoltaic and optical properties. Annealing treatment below the glass transition improved the photovoltaic performance and carrier diffusion in crystal growth of active layer. The X‐ray diffraction patterns indicate a crystalline structure with molecular order of F8T2 in crystal index, 100 as a layer distance between sheets of F8T2 chains. The photovoltaic properties were based on molecular interactions with molecular ordering in active layer at crystal state. As the photovoltaic mechanisms, the F8T2 thin film as p‐type semiconducting polymer worked for electron‐donor layer to support light‐induced generation, carrier diffusion and charge transfer near interface in active layer. Copyright © 2014 John Wiley & Sons, Ltd.     

Neuromelanin in Parkinson’s Disease: Tyrosine Hydroxylase and Tyrosinase

Parkinson’s disease (PD) is an aging-related disease and the second most common neurodegenerative disease after Alzheimer’s disease. The main symptoms of PD are movement disorders accompanied with deficiency of neurotransmitter dopamine (DA) in the striatum due to cell death of the nigrostriatal DA neurons. Two main histopathological hallmarks exist in PD: cytosolic inclusion bodies termed Lewy bodies that mainly consist of α-synuclein protein, the oligomers of which produced by misfolding are regarded to be neurotoxic, causing DA cell death; and black pigments termed neuromelanin (NM) that are contained in DA neurons and markedly decrease in PD. The synthesis of human NM is regarded to be similar to that of melanin in melanocytes; melanin synthesis in skin is via DOPAquinone (DQ) by tyrosinase, whereas NM synthesis in DA neurons is via DAquinone (DAQ) by tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). DA in cytoplasm is highly reactive and is assumed to be oxidized spontaneously or by an unidentified tyrosinase to DAQ and then, synthesized to NM. Intracellular NM accumulation above a specific threshold has been reported to be associated with DA neuron death and PD phenotypes. This review reports recent progress in the biosynthesis and pathophysiology of NM in PD.     

Microstructure of ion-implanted region in TiNi alloy

TiNi alloy samples implanted with various fluences of 3 MeV Cu²⁺ ions were characterized by transmission electron microscope (TEM) and X-ray diffractometer. Cross-sectional TEM images of the samples showed that amorphous region was seen at the fluence of 10¹⁴ ions cm^?2 in case of ion implantation at 300 K of the substrate temperature, but in case of ion implantation at 100 K it did not appear even at 10¹⁵ ions cm^?2. These results were also confirmed by X-ray diffraction profiles of the same samples. Consequently, the extent of microstructure change of TiNi alloy by ion implantation was different depending on the substrate temperature.     

Expression of two Trichoderma reesei xylanases in the fission yeast Schizosaccharomyces pombe

Two xylanase genes (xyn1 and xyn2) were amplified by the polymerase chain reaction (PCR) technique from first-strand cDNA prepared from mRNA of Trichoderma reesei QM9414. The genes were located under the human cytomegalovirus gene promoter (CMVp) on copy-number-controlled plasmids (pTLxyn1 and pTLxyn2). When both plasmids were introduced into Schizosaccharomyces pombe, functional xylanases (XYN I and XYN II) were secreted by the recombinant yeasts. The secreted XYN I protein had a molecular mass of 21 kDa whereas XYN II was produced as two molecular forms with sizes of 21 and 28 kDa, the former being not glycosylated and the latter N-glycosylated. XYN I was secreted in the culture medium at a level of about 25 microg/ml and XYN II at about 170 microg/ml. The recombinant xylanases had the same characteristics with respect to the effects of temperature and pH on the enzyme activity as the native ones.