Energy dispersive spectroscopy‐scanning transmission electron microscope observations of free radical production in human polymorphonuclear leukocytes phagocytosing non‐opsonized Tannerella forsythia

We investigated the association between human polymorphonuclear leukocytes (PMNs) and non‐opsonized Tannerella forsythia ATCC 43037 displaying a serum‐resistant surface layer (S‐layer). When PMNs were mixed with T. forsythia in suspension, the cells phagocytosed T. forsythia cells. Nitro blue tetrazolium (NBT) reduction, indicative of production, was observed by light microscopy; cerium (Ce) perhydroxide deposition, indicative of H₂O₂ production, was observed by electron microscopy. We examined the relationship between high‐molecular‐weight proteins of the S‐layer and Ce reaction (for T. forsythia phagocytosis) using electron microscopic immunolabeling. Immunogold particles were localized within the PMNs and on cell surfaces, labelling at the same Ce‐reacted sites where the S‐layer was present. We then used energy dispersive spectroscopy (EDS)‐scanning transmission electron microscope (STEM) to perform Ce and nitrogen (N) (for S‐layer immunocytochemistry) elemental analysis on the phagocytosed cells. That is, the elemental mapping and analysis of N by EDS appeared to reflect the presence of the same moieties detected by the 3,3′‐diaminobenzidine‐tetrahydrochloride (DAB) reaction with horseradish peroxidase (HRP)‐conjugated secondary antibodies, instead of immunogold labeling. We focused on the use of EDS‐STEM to visualize the presence of N resulting from the DAB reaction. In a parallel set of experiments, we used EDS‐STEM to perform Ce and gold (Au; from immunogold labeling of the S‐layer) elemental analysis on the same phagocytosing cells.     

Three-dimensional fine structure of the biliary tract: Scanning electron microscopy of biliary casts

The three-dimensional structure of the biliary tract was studied by scanning electron microscopy (SEM) of biliary casts. The replica of the biliary tract was successfully prepared by retrograde injection of low viscosity resin into the common bile duct. Bile canaliculi are intricate networks in which hexagonal and pentagonal meshworks are interconnected. Each hexagonal or pentagonal meshwork is on a plane, but adjoining meshworks are on different planes. Bile canalicular networks connect with bile ductules at the periphery of the portal tract. The intrahepatic bile duct showed considerable interspecies variation. The human bile duct has plexiform side branches and periductal sacculi, which are most numerous near the liver hilum and fewest in the smaller portal tracts. The hilar plexus and sacculi are present on opposite sides of the bile duct. The plexus formed at the bifurcation of the bile ducts exhibits a plane. Periductal sacculi were also observed in the monkey and pig bile ducts, particularly the latter, while rat bile ducts possess a peculiar portal bile ductular plexus situated between the portal tract and the surrounding liver parenchyma. No such structures were observed in either the dog or rabbit bile ducts. SEM of the biliary casts showed that the biliary tract was not a simple draining tube but had additional structures, such as periductal sacculi and plexiform side branches. These structures, together with the peribiliary vascular plexus, may be implicated in the modification of bile.     

Elasto-plastic contact analysis of an ultra-high molecular weight polyethylene tibial component based on geometrical measurement from a retrieved knee prosthesis

The wear phenomenon of ultra-high molecular weight polyethylene (UHMWPE) in knee and hip prostheses is one of the major restriction factors on the longevity of these implants. Especially in retrieved knee prostheses with anatomical design, the predominant types of wear on UHMWPE tibial components are delamination and pitting. These fatigue wear patterns of UHMWPE are believed to result from repeated plastic deformation owing to high contact stresses. In this study, the elasto-plastic contact analysis of the UHWMPE tibial insert, based on geometrical measurement for retrieved knee prosthesis, was performed using the finite element method (FEM) to investigate the plastic deformation behaviour in the UHMWPE tibial component. The results suggest that the maximum plastic strain below the surface is closely related to subsurface crack initiation and delamination of the retrieved UHMWPE tibial component. The worn surface whose macroscopic geometrical congruity had been improved due to wear after joint replacement showed lower contact stress at macroscopic level.     

Development of a large-capacity static var generator using self-cornmutated inverters for improving power transmission system stability

A Static Var Generator (SVG) based on a self-commutated inverter using GTO thyristors has been newly developed. The size of the SVG used for improving power system stability will be as large as approximately 100 MVA. The technical subjects to be solved for developing such a large SVG are summarized as follows:

• compact design;
• harmonic elimination by means of multiple transformers; and
• large inverter with series connection of GTO thyristors.

This paper describes the solutions to these subjects, especially the application of a large number of multipulse connection and series connection of GTO thyristors, including the analysis of the basic performance of SVG and the multiple transformer. The test results of a 12-pulse partial model (8 MVA) and a 48-pulse miniaturized model prove the solutions proposed in this paper to be effective and reasonable.     

Motion capture changes to induced motion at higher luminance contrasts, smaller eccentricities, and larger inducer sizes

In the stimulus configuration for "motion capture" phenomenon, we varied luminance contrast of the center disk (target), eccentricity and stimulus size. The subjects had to judge the direction of perceived target motion. We found that motion capture changed to induced motion (the direction of illusory motion was reversed) at smaller eccentricities and larger stimulus sizes. At intermediate eccentricities, motion capture changed to induced motion with increasing luminance contrast of the target. By using magnitude estimation, we also found that even a luminance-defined target was captured ("homochromatic motion capture") and that a moving target was captured by a stationary inducer ("position capture"). Both motion and position capture effects were commonly observed at lower luminance contrasts of the target, larger eccentricities and smaller sizes. From these results, we propose a model of center-surround antagonistic motion contrast detectors in motion processing.     

Visualization of Photoexcited Carrier Responses in a Solar Cell Using Optical Pump—Terahertz Emission Probe Technique

We observed photoexcited carrier responses in solar cells excited by femtosecond laser pulses with spatial and temporal resolution using an optical pump-terahertz emission probe technique. We visualized the ultrafast local variation of the intensity of terahertz emission from a polycrystalline silicon solar cell using this technique and clearly observed the change in signals between a grain boundary and the inside of a grain in the solar cell. Further, the time evolution of the pump–probe signals of the polycrystalline and monocrystalline silicon solar cells was observed, and the relaxation times of photoexcited carriers in the emitter layers of crystalline silicon solar cells were estimated using this technique. The estimated relaxation time was consistent with the lifetime of the Auger recombination process that was dominant in heavily doped silicon used as an emitter layer for the silicon solar cells, which is difficult to obtain with photoluminescence method commonly used for the evaluation of solar cells.     

Thermal isomerization of (all-E)-lycopene and separation of the Z-isomers by using a low boiling solvent: Dimethyl ether

Thermal isomerization of (all-E)-lycopene and the separation of generated Z-isomers were conducted using a low boiling solvent, dimethyl ether (DME). Because of the low boiling point (–24.8°C), DME is easily separated from lipids and other residues and is extremely low residual. The efficiency of thermal Z-isomerization of (all-E)-lycopene in DME was almost equivalent to using hexane. The thermally generated lycopene Z-isomers were separated by utilizing the solubility differences among lycopene isomers and a characteristic of DME that allows the solubility of compounds to be controlled by changing the temperature. Finally, a lycopene mixture containing 72.0% Z-isomers was obtained from (all-E)-lycopene.     

Involvement of Acetobacter orientalis in the production of lactobionic acid in Caucasian yogurt (“Caspian Sea yogurt”) in Japan

Lactobionic acid was first found in a Caucasian fermented milk product popularly known as “Caspian Sea yogurt” in Japan. The presence of lactobionic acid in the fermented milk was indicated by the results of both high-performance anion-exchange chromatographic analysis with pulsed amperometric detection and mass spectrometric analysis. Thereafter, the acid was purified from the yogurt and analyzed by nuclear magnetic resonance. A substantial amount of lactobionic acid was found to be accumulated in the upper layer of the yogurt, especially within 10 mm from the surface. A total of 45 mg of lactobionic acid per 100 g of the upper yogurt layer was collected after 4 d of fermentation. The annual intake of lactobionic acid in individuals consuming 100 g of the yogurt every day would be 0.5 to 1.0 g. A lactose-oxidizing bacterium was isolated from the fermented milk and was identified as Acetobacter orientalis. Washed A. orientalis cells oxidized monosaccharides such as d-glucose at considerable rates, although their activities for substrates such as lactose, maltose, and cellobiose were much lower. When A. orientalis cells were cultivated in cow's milk, they exhibited lactose-oxidizing activity, suggesting that this bacterium was the main organism involved in the production of lactobionic acid in the yogurt.     

Thermoresponsive thin hydrogel-grafted surfaces for biomedical applications

Thin poly(N-isopropylacrylamide) (PIPAAm) hydrogels were introduced onto biomaterials surfaces for accelerating the kinetics of the swelling and shrinking for PIPAAm hydrogels in response to temperature changes. Thin PIPAAm hydrogels on the biomaterials surfaces exhibit rapid and reversible phase transitions and act as switching sequences to regulate the interaction between the surfaces and biological materials by external temperature-induced changes. By utilizing the temperature-dependent changes of thin PIPAAm hydrogels grafted onto surfaces, our laboratory has pursued unique approaches for developing useful biomedical materials as new types of chromatographic matrices and cell culture surfaces.Aqueous thermoresponsive chromatography systems using PIPAAm-grafted stationary phases enable us to separate biomolecules with high biological activity. Additionally, thermoresponsive cell culture surfaces allow for the recovery of confluent cell monolayers, which have been clinically applied to ophthalmological treatments, dilated cardiomyopathy, esophageal ulcerations, periodontal disease, and cartilage injury. Furthermore, next-generation thermoresponsive cell culture surfaces for large-scale cell cultivation and the capture of specific cells have been considered a key technology for expanding small quantities of stem cells and isolating the resulting differentiated cells for therapeutic use.