The Effect of Ethanol on Disassembly of Amyloid-β1-42 Pentamer Revealed by Atomic Force Microscopy and Gel Electrophoresis

The most common type of dementia, Alzheimer’s disease, is associated with senile plaques formed by the filamentous aggregation of hydrophobic amyloid-β (Aβ) in the brains of patients. Small oligomeric assemblies also occur and drugs and chemical compounds that can interact with such assemblies have attracted much attention. However, these compounds need to be solubilized in appropriate solvents, such as ethanol, which may also destabilize their protein structures. As the impact of ethanol on oligomeric Aβ assembly is unknown, we investigated the effect of various concentrations of ethanol (0 to 7.2 M) on Aβ pentameric assemblies (Aβp) by combining blue native-PAGE (BN-PAGE) and ambient air atomic force microscopy (AFM). This approach was proven to be very convenient and reliable for the quantitative analysis of Aβ assembly. The Gaussian analysis of the height histogram obtained from the AFM images was correlated with band intensity on BN-PAGE for the quantitative estimation of Aβp. Our observations indicated up to 1.4 M (8.3%) of added ethanol can be used as a solvent/vehicle without quantitatively affecting Aβ pentamer stability. Higher concentration induced significant destabilization of Aβp and eventually resulted in the complete disassembly of Aβp.     

Catalytic dehydrofluorination of CF3CH3(HFC143a) into CF2CH2(HFC1132a)

The catalytic dehydrofluorination of CF₃CH₃ was studied over various metal phosphate catalysts in a fixed-bed reactor. The Mg₂P₂O₇ catalyst exhibited the moderate activity and high selectivity of CF₂CH₂, and it is the most suitable catalyst for the dehydrofluorination of CF₃CH₃. Deactivation did not take place during the 100 h reaction over the Mg₂P₂O₇ catalyst, and XRD patterns of the catalyst were unchanged after 100 h reaction. However, small amounts of F⁻ ions were present on the surface of the catalyst from results of XPS. The active sites for CF₂CH₂ formation are weak acid sites of the catalysts, and carbon deposition and/or polymerization take place on strong acid sites. Results of CF₃CH₃-TPD indicated that the dehydrofluorination proceeds through a

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carbonium-ion mechanism over Mg₂P₂O₇ catalyst, and the rate-determining step is the cleavage of the C–F bond.     

Selective pyrolysis of polystyrene to that with a desired low polymeric degree

To obtain low polymeric polystyrene (PS), pyrolysis of high polymeric PS in solution was studied in the temperature range from 290 to 400°C by using additives or acid catalysts. The low polymeric PS targeted here was that with average molecular weight of 10⁴. When the feed PS was pyrolyzed in tetralin by adding sulfur or diphenyl disulfide, the molecular weight of PS decreased greatly, even at lower temperatures, and the desired low polymeric PS was formed in a relatively large amount at the temperatures below 350°C. The degradation behavior was able to be explained in terms of a random polymer chain scission mechanism initiated by sulfur radicals formed from the additives. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2299–2305, 1998     

Analysis of the Chernobyl accident from 1:19:00 to the first power excursion

Many researchers have reported that the root cause of the Chernobyl accident has not been clarified still now. Since many of them discussed the accident without a precise thermal-hydraulic investigation, thermal-hydraulic calculations coupled with neutronic calculations have been done on the basis of the recorded result at the Chernobyl Unit-4. Plant configurations and operational conditions were given to the code on the basis of reported result and published papers. Calculation could trace plant parameters from 1:19:00 to the first power excursion without any discrepancies measured at the Chernobyl Unit-4. Reactivity slightly smaller than 1β by the positive scram is concluded as a possible direct cause of the accident, which acts as a trigger to increase the reactor power. Other possibilities as a trigger of the accident such as cavitation in pumps and pump coast-down were investigated. The importance of the calculation from the stable condition is also described in this paper in order not to bring unnecessary assumptions into the calculation.     

Effects of humic substances on the pattern of oxidation products of pentachlorophenol induced by a biomimetic catalytic system using tetra(p-sulfophenyl)porphineiron(III) and KHSO5

In the presence of humic substances (HSs), the oxidative conversion of pentachlorophenol (PCP) was found to be efficiently catalyzed by tetra(p-sulfophenyl)porphineiron(III) (Fe(III)-TPPS) using KHSO5 as an oxygen donor. Ortho-tetrachloroquinone (o-TeCQ), 2-hydroxyl-nonachlorodiphenyl ether (2H-NCDE), 4-hydroxyl-nonachlorodiphenyl ether (4H-NCDE), and octachlorodibenzo-p-dioxin (OCDD) were identified as the major byproducts of the reaction. Decreased amounts of these byproducts were produced in the presence of HS. In particular, the addition of HSs with a lower degree of humification resulted in a large decrease in the formation of dimers, such as 2H-NCDE, 4H-NCDE, and OCDD. More than 60% of the chlorine, which was released from PCP, was found in the HS fractions after the reaction. This suggests that chlorinated intermediates from PCP were incorporated into the HS. Pyrolysis-GC/MS and 13C NMR studies confirmed that the binding of the chlorinated intermediates was covalent in nature and that the intermediates were copolymerized with HS via oxidative coupling reactions. A Microtox test demonstrated that the toxicity of the HS fraction containing PCP-derived intermediates was much lower than that of the mixture of PCP and HS in the absence of a catalytic reaction.     

Microstructural investigation of ceria-zirconia solid solution with oxygen vacancies

The microstructural change in CeO2-ZrO2 solid solution (Ce2Zr2O7 + x; 0 < or = x < or = 1) with an ordered arrangement of Ce and Zr associated with the absorption/release of oxygen was observed by transmission electron microscopy (TEM). The oxidation of Ce2Zr2O7 was observed in TEM by electron diffraction analysis. The change in the electron diffraction pattern shows that Ce2Zr2O7 was easily oxidized in the TEM and that the oxidation was completed, giving an intermediate phase Ce2Zr2O7.5. Three different lattice images corresponding to x = 0, 0.5 and 1.0 were observed in high-resolution photographs of Ce2Zr2O7 + x. This difference in contrast image may be used for determining the local amount of oxygen absorbed.     

In situ HREM observation of nucleation and growth of nanotwins beneath the solid-liquid interface in Si

Nucleation and growth of nanotwins in Si grown from Al-Si liquid have been observed directly using an in situ heating experiment in a high-resolution transmission electron microscope. Nanotwins are nucleated at the triple point between a vacuum and the solid-liquid interface. When two parallel twins, the mirror planes of which are separated slightly, encounter each other, very complicated atomic arrangements are formed. The structure of the perturbed region is discussed tentatively in terms of the high-pressure phases in Si.     

Microbial treatment of bis (2-ethylhexyl) phthalate in polyvinyl chloride with isolated bacteria

In this study, we investigated the use of microbes to degrade and remove bis (2-ethylhexyl) phthalate (DEHP), a common plasticizer and a suspected endocrine disruptor, exuding from polyvinyl chloride. Four species of bacteria that utilize DEHP as their sole carbon source were isolated from garden soil, one of which, strain NK0301, was markedly more efficient than the others in degrading DEHP and was chosen for further studies. Strain NK0301 was a coryneform bacterium (1.5x1.0 microm) identified as Mycobacterium sp. from its 16S rDNA sequencing homology. It readily degraded DEHP to two major products determined by gas chromatography/mass spectrometry to be 2-ethylhexanol and 1,2-benzenedicarboxylic acid. Other phthalate esters, suspected of being endocrine disruptors, were also tested and all except two could be utilized by strain NK0301 as their sole source of carbon. When strain NK0301 was cultivated on polyvinyl chloride sheets containing DEHP as the plasticizer, it removed up to 90% of DEHP in 3 d. Following this treatment, the polyvinyl chloride sheets did not exude DEHP to artificial saliva.     

Numerical analysis of freezing domain around inground storage tanks for cryogenic liquids using integrated penalty,and finite difference,methods

Many numerical schemes for analyzing transient linear heat conduction with phase change have been proposed by several researchers. Recently, the “integrated penalty” method and the finite difference method were jointly applied by the authors (1978) to solve the phase problem with a free boundary, the results of which were compared with Neumann's theoretical solution, showing a very satisfactory agreement in both the temperature distribution and the magnitude of the freezing domain. The same procedure was also used to analyze the behavior of the freezing domain around a cryogenic inground storage tank. Further, this joint application method was applied to solve more complex problems such as the freezing of the soil around cryogenic inground storage tanks having thermal shields, the behavior of freezing domains mutually interacting among four tanks and the case involving multiple free boundaries, for example, the thawing of a tundra surface. This analytical approach, making joint use of both the integrated penalty method and the finite difference method, was found to be very effective for solving problems which include the four states of frozen, thawed, refrozen and unfrozen soils.     

Interfacial properties of a direct bonded Nd-doped YVO4 and YVO4 single crystal

Laser crystal bonding of a neodymium-doped yttrium orthovanadate (Nd : YVO₄) and a non-doped yttrium orthovanadate (YVO₄) crystal as a cold finger has been demonstrated. Instead of a traditional chemical treatment, a newly developed dry etching process was applied to the preparation for contact of mechanically polished surfaces. In the subsequent heat treatment process, stable heating at 873 K was required to prevent precipitation at the bonded interface. The bonded interface of 3 mm×3 mm was investigated by optical scattering and wavefront distortion measurements. The scattering density around the bonded interface was less than 4.6×10⁶/cm³ and the wavefront distortion caused by the bonded region was assumed to be around 0.04 at 633 nm. Additional magnified inspection showed that atoms in the bonded region were well arranged with the same regularity as the bulk crystal. The diffusion coefficient of Nd³⁺ ions in the YVO₄ crystal was estimated at 2.3×10^–23 m²/s at 873 K.