Relationship between prostaglandin E2 concentrations in periapical exudates from root canals and clinical findings of periapical periodontitis

In this study the relationship of prostaglandin E2 (PGE2) concentrations in periapical exudates with clinical findings of teeth with periapical periodontitis is discussed. Periapical exudate samples were obtained from root canals of 77 endodontically involved teeth during routine root canal treatment by the quantitative sampling method using paper points. PGE2 concentrations in periapical exudates (PE-PGE2) were determined by radioimmunoassay. Significantly higher levels of PGE2 were found in periapical exudates from teeth with radiolucent areas than from teeth without radiolucent areas (236.8 +/- 521.3 pg/microliter vs. 14.9 +/- 23.1 pg/microliter, respectively). The elevated PE-PGE2 levels were associated with the presence of clinical symptoms that reflected an acute inflammation in the periapical lesion. In contrast, a significantly negative association of decreased PE-PGE2 levels with increasing size of radiolucent areas was demonstrated. These results suggested that PGE2 was produced locally in periapical lesions and that the PGE2 concentration in periapical exudate could reflect the state of the disease activity in periapical periodontitis.     

Not Oligomers but Amyloids are Cytotoxic in the Membrane‐Mediated Amyloidogenesis of Amyloid‐β Peptides

The formation of neurotoxic aggregates by amyloid‐β peptide (Aβ) is considered to be a key step in the onset of Alzheimer's disease. It is widely accepted that oligomers are more neurotoxic than amyloid fibrils in the aqueous‐phase aggregation of Aβ. Membrane‐mediated amyloidogenesis is also relevant to the pathology, although the relationship between the aggregate size and cytotoxicity has remained elusive. Here, aggregation processes of Aβ on living cells and cytotoxic events were monitored by fluorescence techniques. Aβ formed amyloids after forming oligomers composed of ≈10 Aβ molecules. The formation of amyloids was necessary to activate apoptotic caspase‐3 and reduce the ability of the cell to proliferate; this indicated that amyloid formation is a key event in Aβ‐induced cytotoxicity.     

Image analysis system for evaluating sliding behavior of a liquid droplet on a hydrophobic surface

An analysis system was developed to evaluate the sliding behavior of a liquid droplet on a hydrophobic surface. This system enables continuous and simultaneous measurement of both the sliding acceleration and shape deformation during the sliding of a liquid droplet. Moreover, the velocity vector of the internal fluidity of a sliding droplet was obtained by employing particle image velocimetry in the analysis system. This evaluation method pioneers the measurement of the dynamic wettability of a hydrophobic solid surface.     

Synthesis of poly[2-(N,N-dimethyl)aminoethyl methacrylate-co-acrylonitrile]

Summary Radical copolymerization of 2-(N,N-dimethyl)aminoethyl methacrylate (1) and acrylonitrile (2) initiated by 2,2-azobis(2-methylpropionitrile) was carried out. The sequence distributions of the copolymers were investigated by ¹³C NMR spectroscopy. A terminal model was used to interpret the propagation process in the copolymerization. The monomer reactivity ratios in the bulk copolymerization at 45°C were evaluated as r₁=1.06 and r₂=0.07. Radical reactivity indices and frontier electron densities for 1 and 2 were calculated.     

Structure of $$\langle 110 \rangle $$-tilt boundaries in cubic zirconia

Atomic structures of \(\langle 110 \rangle \)-symmetrical tilt grain boundaries in yttria-stabilized cubic zirconia are investigated from a mathematical perspective. We predicted the unique arrangement of structural units along the grain boundaries which was confirmed experimentally by atomic-resolution scanning transmission electron microscopy.     

Dissociation reaction of the 1/3$$ \left\langle {\bar{1}101} \right\rangle $$ edge dislocation in α-Al2O3

It has been reported that dislocations with 1/3\( \left\langle {\bar{1}101} \right\rangle \) edge component of the Burgers vector are formed in {1\( \bar{1} \)04}/\( \left\langle {11\bar{2}0} \right\rangle \) low-angle grain boundaries of alumina (α-Al₂O₃). These dislocations dissociate into two partial dislocations with a stacking fault on the (0001) plane (Tochigi et al. in J Mater Sci 46:4428–4433, 2011). However, the dissociation reaction of these dislocations has not been determined so far. In this study, the structures of the dissociated dislocations and the (0001) stacking fault were investigated by transmission electron microscopy and theoretical calculations. It was revealed that the dissociated dislocations were generated from the 1/3\( \left\langle {\bar{1}101} \right\rangle \) perfect edge dislocation by the reaction of 1/3\( \left\langle {\bar{1}101} \right\rangle \) → 1/18\( \left\langle {\bar{4}223} \right\rangle \) + 1/18\( \left\langle {\bar{2}4\bar{2}3} \right\rangle \). Furthermore, electron energy loss spectroscopy analysis was performed to examine the atomic/electronic structure of the (0001) stacking fault. In the observed spectra, a chemical shift and intensity decrease were found at the oxygen K-edge. Theoretical spectrum analysis using first-principles calculations revealed that the characteristic features of the spectra are originated from the local atomic configurations of the (0001) stacking fault.     

Direct Evidence of Dopant-Enhanced Grain-Boundary Sliding in Yttria-Stabilized Zirconia Bicrystals

Compression tests were conducted at 1400°C in air for undoped and Si-doped yttria-stabilized zirconia (YSZ) bicrystals with the same orientation relationship (Σ=5, [001]/{210} grain boundary). It was found that the macroscopic grain-boundary slidings are observed during the deformation in both undoped and doped bicrystals, and the sliding displacements increase almost linearly with increasing total displacements. It is distinctly demonstrated that the Si-doped bicrystal exhibits a sliding displacement that is a few times larger than the undoped bicrystal. In addition, the total strain of the Si-doped bicrystal at a failure is much larger than that of the undoped bicrystal. It can be stated that Si doping in YSZ not only enhances the grain-boundary sliding but also suppresses its failure.     

Analysis of particle trajectories of small particles in flotation when the particles and bubbles are both charged

The trajectory of a small particle moving to a bubble surface was analyzed by taking into account the effects of surface charges of the bubble and particle and the short range hydrodynamic interaction near the bubble surface, in a flotation process. The particle trajectories obtained theoretically were in good agreement with those obtained by direct observation. Even if the signs of the surface charges of the bubble and particle were the same, the particle adhered to the bubble surface when the net surface force, that is, the sum of the electrostatic force and the van der Waals force, was attractive. Particle capture efficiency, η_S, per bubble was estimated by trajectory analysis and the flotation efficiency, η_T, was calculated. The values of η_T calculated by the particle trajectory analysis were in reasonable agreement with those obtained experimentally. The dependence of particle diameter on η_T was also examined by the particle trajectory analysis.     

Thermo-molecular gas-film lubrication (t-MGL) analysis for heat-assisted magnetic recording head sliders

In the present paper the static lubrication characteristics of a slider flying over a running boundary wall with arbitrary local temperature distributions are analyzed using the thermomolecular gas-film lubrication (t-MGL) equation. We obtain two approximate solutions: (a) a linearized solution when the temperature deviation is small ( \( \tau_{W} \ll 1 \) ) and arbitrarily distributed, and (b) a solution for the case with a very large bearing number \( (\varLambda \to \infty ) \) . We herein numerically calculate the static lubrication characteristics and verify the validities of these two approximate solutions. Moreover, we calculate the characteristics for various temperature distributions produced by laser heating.