Electroluminescent devices with poly(methylphenylsilane) film doped with Eu3+ complexes were fabricated. The cell structure of glass substrate/indium-tin-oxide/polysilane/electron transport layer/Mg/Ag was employed. Sharp red electroluminescence of europium ion was obtained at dc bias voltage of over 12 V.
Glassy perfluoropolymers have become an exciting materials platform for membrane gas separation as they define the upper bounds for some gas separations, such as He/H 2 , He/CH 4 , and N 2 /CH 4 . However, due to the difficulty in synthesis, only a few glassy perfluoropolymers are commercially available, including Teflon AF and Hyflon AD derived from dioxoles and Cytop derived from dihydrofuran. In this study, two perfluoropolymers based on dioxolanes, poly(perfluoro-2-methylene-1,3-dioxolane) (poly(PFMD)) and poly(perfluoro-2-methylene-4-methyl-1,3-dioxolane) (poly(PFMMD)), were synthesized by radical polymerization and characterized thoroughly for physical properties such as glass transition temperature (T g ), d-spacing between polymer chains, and fractional free volume (FFV). The gas permeability and solubility were determined at 35 °C for a series of pure gases in these perfluorodioxolanes and compared with the commercial perfluoropolymers. Poly(PFMD) and poly(PFMMD) exhibit separation properties of He/H 2 , He/CH 4 , H 2 /CH 4 , H 2 /CO 2 , and N 2 /CH 4 near or above the upper bounds in Robeson's plots, and superior to the commercial perfluoropolymers, despite their similar T g and FFV. The underlying reasons for the superior gas separation properties in these dioxolane-based perfluoropolymers are discussed.
Rapid improvements in polymer-electrolyte fuel-cell (PEFC) performance have been driven by the development of commercially available ion-conducting polymers (ionomers) that are employed as membranes and catalyst binders in membraneelectrode assemblies. Commercially available ionomers are based on a perfluorinated chemistry comprised of a polytetrafluoroethylene (PTFE) matrix that imparts low gas permeability and high mechanical strength but introduces significant mass-transport losses in the electrodes. These transport losses currently limit PEFC performance, especially for low Pt loadings. In this study, we present a novel ionomer incorporating a glassy amorphous matrix based on a perfluoro(2methylene-4-methyl-1,3-dioxolane) (PFMMD) backbone. The novel backbone chemistry induces structural changes in the ionomer, restricting ionomer domain swelling under hydration while disrupting matrix crystallinity. These structural 1 changes slightly reduce proton conductivity while significantly improving gas permeability. The performance implications of this tradeoff are assessed, which reveal the potential for substantial performance improvement by incorporation of highly permeable ionomers as the functional catalyst binder. These results underscore the significance of tailoring material chemistry to specific device requirements, where ionomer chemistry should be rationally designed to match the local transport requirements of the device architecture.
SUMMARY An epidemiological study of cerebrovascular disease in Akabane and Asahi, Japan, was made. (These cities are located near Nagoya, Japan.) The study population included 4,737 men and women aged 40 to 79 at the time of entry into the study. There were 4,186 persons who were examined and, of these, 264 cases of cerebrovascular attacks were observed between 1964 and 1970. The incidence rate of stroke in those persons not responding to the survey was 15.9 times higher than in those persons examined according to person-year observation in Akabane. The risk factors for cerebral hemorrhage and thrombosis were evaluated by age-adjusted and sex-adjusted relative risks. The predisposing factors to cerebral hemorrhage appeared to be high blood pressure, high left R wave, ST depression, T abnormality, capillary fragility counts, previous medical history of stroke, and albuminuria. For cerebral thrombosis, the predisposing factors appeared to be high blood pressure, ST depression and funduscopic sclerotic findings, and those factors assumed to be significant were glycosuria and smoking habits. Ocular funduscopic abnormality was the most prominent risk factor for cerebral thrombosis, while high blood pressure and ECG abnormalities were highly related to cerebral hemorrhage. It was suggested that those subjects with a relatively higher blood pressure may have a higher relative risk of cerebral hemorrhage than those with a lower (normal range) blood pressure. A previous or family history of stroke also appeared significantly related to cerebral hemorrhage.
The uptake of methylene blue (MB), and toluidine blue O (TBO) by bovine pulmonary arterial endothelial cells grown on microcarrier beads was detected as a decrease in the concentration of dye in the medium after these thiazine dyes were added to the medium surrounding the cells. Because the reduced forms of these dyes are much more lipophilic than the oxidized forms, we considered the possibility that reduction of the dyes at the cell surface might have preceded the uptake by the cells. Therefore, we studied the ability of the cells to reduce a toluidine blue O-polyacrylamide polymer (TBOP), which was too large to enter the cells in either the oxidized or reduced form. The TBO moieties of the polymer were reduced by the cells, indicating that the dyes did not have to enter the cells to be reduced and that reduction can occur at, or near, the cell surface. The rate of TBOP reduction was about the same as the rate of uptake of the monomeric dyes, indicating that the cell surface reduction mechanism had a sufficient capacity to account for the monomer uptake by the cells. We also found that ferricyanide ion, which also did not permeate the cells, was reduced by the cells and that external ferricyanide inhibited the monomeric MB uptake. Thus the results with ferricyanide were also consistent with the concept that the monomeric thiazine dyes are reduced at the cell surface before the more lipophilic reduced forms are taken up by the endothelial cells.
The objective of this study was to validate the efficacy of Takeuchi classification for lateral hinge fractures (LHFs) in open wedge high tibial osteotomy (OWHTO). In all 74 osteoarthritic knees (58 females, 16 males; mean age 62.9 years, standard deviation 7.5, 42 to 77) were treated with OWHTO using a TomoFix plate. The knees were divided into non-fracture (59 knees) and LHF (15 knees) groups, and the LHF group was further divided into Takeuchi types I, II, and III (seven, two, and six knees, respectively). The outcomes were assessed pre-operatively and one year after OWHTO. Pre-operative characteristics (age, gender and body mass index) showed no significant difference between the two groups. The mean Japanese Orthopaedic Association score was significantly improved one year after operation regardless of the presence or absence of LHF (p = 0.0015, p < 0.001, respectively). However, six of seven type I cases had no LHF-related complications; both type II cases had delayed union; and of six type III cases, two had delayed union with correction loss and one had overcorrection. These results suggest that Takeuchi type II and III LHFs are structurally unstable compared with type I. Cite this article: Bone Joint J 2015;97-B:1226-31.
Eu3+, Tb3+, and Co2+ salts of polymers containing carboxylic acid and sulfonic acid ligands were prepared and characterized. The polymers investigated were poly(acrylic acid) (PAA), copolymers of styrene-acrylic acid (PSAA), styrene-maleic acid (PSM), and methyl methacrylate-methacrylic acid (PMM/MA), and partially carboxylated and sulfonated polystyrenes (CPS and SPS). The lanthanide salts of these polymers showed characteristic lanthanide ion fluorescence in the solid state on excitation with UV light. The fluorescence excitation and emission spectra of these salts excepting carboxylated polystyrene showed characteristic spectra of the free ions, indicating that no energy is transferred from the polymer matrix to the ions. The carboxylated polystyrene-Eu3+ and -Tb3+ showed broad excitation spectra similar to the spectrum of the polymer and emission from the lanthanide ions, suggesting energy transfer from the polymer to the ion. The fluorescence intensities of the lanthanide salts of PAA, PSM, CPS, and SPS were found to increase linearly with the metal ion content. However, the salts of PSAA and PMM/MA displayed typical fluorescence concentration quenching behavior, reaching a maximum at 4-6 wt % of metal and decreasing with further increases in metal content. These results suggest that PSAA and PMM/MA contain ionic aggregates in which Eu and Tb ions are located close together. The energy transfer from Tb3+ to Co2+ and Eu3+ was evaluated from the Tb3+ fluorescence quenching. This was much more efficient in PSAA than in CPS and SPS systems.These results confirm that ion aggregates exist in PMM/MA and PSAA but not in the CPS and SPS systems at low metal concentration (<6 mol %). The probability Pd~a of dipole-dipole transfer between Tb3+ and Co2+ statistically distributed in a polymer matrix and the quenching characteristics were calculated by using Forster's equation. Experimental fluorescence quenching behaviors for PASS, CPS, and SPS are discussed as compared with the calculated quenching curve.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.