Lindeman's melting law and solidus curve under pressure of Al–Si and Al–Ge solid solutions

Using the pressure dependence of the mean-square displacement, the compression effect on the melting temperature of matrix Al is studied by Lindeman's melting law. The melting curve obtained increases as a function of the pressure and is in good agreement with the observed tendency for Al. The contribution of the transverse-like acoustic modes to the mean-square displacement is important for Al and becomes more predominant under pressure. Then, considering the contributions from the band and local mode frequencies, the temperature- and pressure-dependent mean-square displacement is quantitatively calculated for Al–Si and Al–Ge solid solutions. The concentration dependence of the Debye temperature at high and low temperatures is estimated, and the pressure effect on the solidus curves is presented by applying Lindeman's melting law to the Al–Si and Al–Ge alloy systems. © 1998 Chapman & Hall     

Stromal vascularization in the endometrium during adenomyosis

In adenomyosis, the two major frequent symptoms are hypermenorrhea and dysmenorrhea. The incidence of the former is said to be high, ranging from 36 to 70%. It has been found that vascular distribution of the endometrium in adenomyosis is diversely different from fertile patients without adenomyosis. For example, hysteroscopy revealed that approximately half of the patients have abnormal vascularization. In these patients, vascular distribution was generally irregular, and vessels were thick, dilated, and/or reticular in some patients. Moreover, morphometric analysis of the endometrium revealed that in the fertile women, the mean surface area, total surface area, and total number of capillaries, all increased significantly in the secretory phase compared to the proliferative phase. In contrast, the above parameters increased in the adenomyosis group in both the proliferative phase and secretory phase compared to the fertile women. In particular, the total surface area of capillaries per mm(2) markedly rose, by 11.6 times, compared to that of the proliferative phase in the fertile women. These findings suggest that regulatory factors involved in the vascular proliferation are diversely exaggerated, and that the abnormal vascularization of the endometrium is closely related with hypermenorrhea.     

Copper ⇌ Alkali Ion Exchange of Alkali Aluminosilicate Glasses in Copper-Containing Molten Salt: II, Divalent Copper Salts, CuCl2 and CuSO4

The ion-exchange mechanism between copper and alkali ions, when 20R₂O · 10Al₂O₃· 70SiO₂ (R = Li, Na, and K) glasses are immersed in divalent copper-containing molten salts in air and nitrogen at 550°C, has been investigated. In molten CuCl₂, the ion-exchange behavior in both air and nitrogen was very close to that in molten CuCl in air reported previously. This is explained by assuming that CuCl₂ decomposes into CuCl and Cl₂ at 550°C and the Cu⁺ ions thus formed mainly diffuse in glasses to replace alkali ions, where Cl₂ acts as an oxidizing agent just like oxygen. In the case of molten CuSO₄─₂SO₄, a small amount of Cu⁺ which is present in the molten state plays a primary role in the Cu ⇌ R⁺ ion exchange process, although the contribution of direct Cu²⁺⇌ 2R⁺ ion exchange cannot be ignored.     

Investigation of novel PCBM analogs containing thienyl groups for organic photovoltaic devices

Novel [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) analogs containing benzo[b]thiophene and thieno[3,2-b]thiophene were used as electron acceptors in bulk heterojunction thin layer organic photovoltaic devices. The solubility of the novel methanofullerenes in dichloromethane significantly varied, and es-TThCBM, which was 1.4 times as soluble as PCBM, exhibited maximum solubility. The morphology of the thin films prepared from the mixtures of these methanofullerenes with regioregular poly(3-hexylthiophene) (P3HT) was investigated by XRD, AFM, and UV–vis absorption spectroscopy. Devices containing the novel methanofullerenes exhibited nearly the same performance as those containing PCBM.     

Conductance stopped-flow study of cationic polymerizations of p-methoxystyrene and styrene

Summary Conductance stopped-flow analysis on the initial phase of cationic polymerizations of p-methoxystyrene and styrene revealed rapid changes in conductance (within 20–50 ms) that were related to the initiation process. Initiation rate constants were obtained for CF₃SO₃H, CH₃COClO₄, and BF₃O (C₂H₅)₂ initiators in 1,2-dichloroethane at 30°C. They agreed closely with those determined by stopped-flow spectroscopy, and decreased with increasing monomer concentration.     

Processing of highly oriented (K,Na)NbO3 thin films using a tailored metal-alkoxide precursor solution

Highly oriented lead-free K_0.5Na_0.5NbO₃ (KNN) thin films were synthesized by chemical solution deposition. The analysis of the KNN precursor solution revealed that the KNN precursor consists of complex metal alkoxides of potassium and sodium hexaalkoxy niobates with highly symmetric Nb-O octahedra. KNN precursor films were crystallized in a perovskite phase with a (1 0 0) preferred orientation on Pt(1 0 0)/MgO(1 0 0) substrates at 650 °C. The three-dimensional relationship between KNN(1 0 0) and Pt(1 0 0)/MgO(1 0 0) is confirmed by the fourfold symmetry of the pole figure. The fourfold symmetry indicates that the synthesized films are oriented in both the c and a, b directions on the Pt(1 0 0) surface. Although the insulating resistance was not sufficiently high at room temperature, the (1 0 0)-oriented KNN thin films showed potentially larger polarizations compared to the KNN thin films with no preferred orientation at low temperatures. The 2P_r and 2E_c of the oriented KNN films at −190 °C were 41.0 μC/cm² and 90 kV/cm, respectively.     

Processing of Novel Strontium Titanate-Based Thin-Film Varistors by Chemical Solution Deposition

Strontium titanate (SrTiO₃)-based multilayered film with varistor characteristics has successfully been fabricated by a chemical solution deposition (CSD) method. Homogeneous precursor solutions of SrTiO₃ and Nb:SrTiO₃ with long-term stability could be prepared by optimizing the reaction conditions among strontium ethoxide, titanium isopropoxide, and niobium ethoxide. Films were prepared using the precursor solutions on fused silica substrates at 700°C. Triple layered films with SrTiO₃/Nb:SrTiO₃/SrTiO₃ structure were also successfully crystallized on Pt/Ti/SiO₂/Si substrates at 700°C. The current–voltage ( I - V ) curve of the multilayered film was characteristic to varistors and the nonlinear coefficient α of the synthesized film was ∼3.0. The varistor voltages ( E _0.01) of 0.6-μm-thick film were 140 kV/cm for the forward direction and −120 kV/cm for the reverse direction, respectively, at room temperature.     

Leaching of Lead and Connectivity of Plumbate Networks in Lead Silicate Glasses

The formation of a plumbate network in binary lead silicate glasses was examined based on the leaching behavior of Pb²⁺ in lead silicate glasses over a wide composition region. The effective diffusion coefficient of Pb²⁺ at 40°C was on the order of 10⁻¹⁷ m²/s for PbO<35 mol% glasses, and increased three orders of magnitude for 35–50 mol% PbO contents. Such a steep composition dependence is considered to be because of changes in the medium or longer range structure. That is, it is proposed that the plumbate network forms a percolative 3D network in the composition region to form diffusion paths for the lead ions. In addition, the present results indicate that the lead ion exists as a network former over the entire glass forming composition range of the binary silicate glasses.