Increasing chemisorbed silane coupling agents in surface-treated layer of silica particles

In the surface treated inorganic particles with silane coupling agent (SCA), chemisorbed and physisorbed molecules are present in the treated layer. Increasing the amount of chemisorption by increasing the molecular weight of SCAs was investigated. Oligomers formed via self-condensation during storage more than 10 days at room temperature for 3-methacryloxypropyltrimethoxysilane-treated silica particles. Monomeric SCA evaporates easily by heating. The oligomers restrict evaporation, and heating increases the chemisorption. The influence of molecular weight of SCA was investigated. In the case of amino group, the amount of chemisorbed was greater for aminoethylaminooctyltrimethoxysilane with high molecular weight than for 3-aminopropyltriethoxysilane. For SCAs with hydrocarbon chains, the amount of chemisorption was lower for both low molecular weight molecules and decyltrimethoxysilane (D) with a high molecular weight. For fluorocarbon chains, the amount of chemisorption was lower for low molecular weight molecules, whereas it increased significantly by heating for high molecular weight type of 1H,1H,2H,2H-heptadecafluorodecyltriethoxysilane (F). Wide-angle X-ray diffraction analysis of F-treated silica particles showed that the fluorocarbon chains formed an ordered structure. There was no such indication for the D-treated system. This ordered structure seems to influence on higher chemisorption for F-treated systems.     

Bulge forming of braided thermoplastic composite tubes under axial compression and internal pressure

In this study, the bulge forming of fiber reinforced thermoplastic (FRTP) composite braided tubes was studied as a new forming technique utilizing fiber orientation rearrangement (the trellis effect) at temperatures near the matrix melting point. It is shown that free bulge forming with the trellis effect can easily result in high expansion without buckling only by axial compression. This is when the stress of the matrix is small enough to rearrange the fiber orientation of the braid. To improve the surface quality and dimensional accuracy, bulge forming with closed dies and internal pressure was also examined experimentally. The appropriate conditions for axial penetration and internal pressure are established. The kinematics of braid is also considered, and calculations from the model are evaluated from experiments. In addition, the kinematic state of braid after deformation is simulated by calculation from the geometric braid model. It is found that the “normalized profile” of the bulged tube does not change during the process and the thickness of the matrix depends on changing fiber orientation.     

Preparation of [001]- and [107]-Oriented Epitaxial YbBa2Cu4O8 Films Prepared by Coating-Pyrolysis Process

YbBa ₂ Cu ₄ O ₈ (Yb124) films were prepared on SrTiO ₃ (001) and SrTiO ₃ (110) substrates by coating-pyrolysis process at ambient pressure, and the alignments of these films were investigated by XRD -2 scanning and XRD pole-figure analysis. Films prepared on SrTiO ₃ (001) consisted of almost single-phase [001]-oriented epitaxial Yb124. On the other hand, films on SrTiO ₃ (110) consisted of [107]-oriented epitaxial Yb124 and other impurity phases, one of which was considered to be so-called other perovskite phase.     

Solid-state electrochemical CO2 gas sensors based on sodium ionic conductors

The sensing characteristics of a solid-state electrochemical CO₂ gas sensor, expressed as PtO₂, Na₂O Na ionic conductor Na₂CO₃CO₂, O₂Pt were investigated in terms of a two-electron electrochemical reaction. The number of electrons for the cell reaction was higher than 2 and approached 2 with an increase in the operating temperature up to about 500 °C. The introduction of water vapour induced a lowering of the e.m.f. and a prolongation of the response time. The formation of sodium oxides in the Na₂CO₃ layer was considered as a possible cause of these water effects. The sensing characteristics recovered completely after the water vapour was cutoff. The e.m.f. reduction due to water sorption was depressed by using a densified Na₃Zr₂Si₂PO₁₂. A densified Na₃Zr₂Si₂PO₁₂-based electrolyte is preferable for use as a gas sensor with a fast response and high stability for detection of CO₂ in air.     

Sample pretreatment for aggregate-free PVC molecular weight measurement by size-exclusion chromatography

The procedure of aggregate-free poly(vinyl chloride) (PVC) solutions for size-exclusion chromatography (SEC) at room temperature using tetrahydrofuran (THF) as the mobile phase is proposed. PVC was dissolved in 1,2,4-trichlorobenzene (TCB) at 130 or 140°C for 6 h, precipitated in methanol, filtrated, and dried. The pretreated PVC was again dissolved in THF and SEC measurements were performed at room temperature. High molecular weight (MW) PVC required a higher pretreatment temperature of 140°C. The existence of aggregates sometimes could not be observed by a refractive index detector, but a light-scattering detector attached to the SEC columns could detect them clearly. The slope of the relationship between the MW and retention volume at the high MW region was steep compared with that at the other part of the peak and it was also a good indicator of the existence of aggregates. The pretreatment of PVC resulted in the decrease in MW averages, which was attributed to the disappearance of aggregates and not to the degradation of PVC. The pretreatment at 150°C resulted in the degradation of PVC. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1801–1809, 1998     

Collagenous crystalloids in a fine needle aspirate of a pleomorphic adenoma of the minor salivary gland. A case report

BACKGROUND: Collagenous crystalloids were previously observed in histologic sections of pleomorphic adenoma. However, to the best of our knowledge, there have been no English-language reports dealing with collagenous crystalloids in fine needle aspirates. CASE: A fine needle aspiration specimen obtained from a mass in the hard palate of a 52-year-old female revealed collagenous crystalloids. The crystalloids were yellow to green, measured 30-50 microns in diameter and were radially arranged. CONCLUSION: This case indicates that collagenous crystalloids in salivary gland aspirates may be a clue to the diagnosis of pleomorphic adenoma.     

Predisposing factors for severe mitral regurgitation in idiopathic mitral valve prolapse

To elucidate predisposing factors for severe mitral regurgitation (MR) in idiopathic mitral valve prolapse (MVP), 124 MVP patients were classified into the following categories: 55 with isolated clicks (click group), 35 with a late-systolic murmur (late-SM group), and 34 with a holosystolic murmur (holo-SM group). Their clinical and echocardiographic findings were compared with those of 26 patients with spontaneous chordal rupture (rupture group). In 22 patients in the click group, 24 in the late-SM group, and 22 in the holo-SM group, follow-up studies were performed for a mean of 4.5 years (range 1 to 13.5). The mean age was youngest in the click group and oldest in the rupture group. The click and late-SM groups showed a female predominance, but the holo-SM and rupture groups showed a male predominance. There was no difference in the incidence of systemic hypertension among the 4 groups. Most patients in the click and late-SM groups had anterior leaflet prolapse. In the holo-SM and rupture groups, however, the incidence of posterior leaflet involvement was significantly increased. The incidence of thickened mitral valve increased in order of the click (8%), late-SM (21%), holo-SM (38%), and rupture (50%) groups. Six patients in the holo-SM group developed chordal rupture with severe MR during the follow-up period. In the click and late-SM groups, however, there were no complications and no development into a holo-SM. Thus, aging, male sex, posterior leaflet prolapse, thickened mitral valve, and holo-SM were found to be important predisposing factors for severe MR in idiopathic MVP.