112 research outputs found

    1 H and 19 F FFC-NMR of catalyst layer materials for polymer electrolyte membrane fuel cells

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    1H and 19F spin lattice relaxation rates of catalyst layer materials (CLM) of polymer electrolyte membrane fuel cells were measured by the fast field cycling (FFC) method. In contrast to ionomer membranes, 1H relaxation rates of adsorbed water in both platinum-Ketjen black (Pt-KB) catalyst powder and CLM were strongly dependent on Larmor frequency approximated by a power law due to the strong surface interaction of adsorbed water. The difference in the frequency dependence in the Pt-KB and the CLM was attributed to higher acidity of the CLM

    An Estradiol-Inducible Promoter Enables Fast, Graduated Control of Gene Expression in Fission Yeast [preprint]

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    The fission yeast Schizosaccharomyces pombe lacks a diverse toolkit of inducible promoters for experimental manipulation. Available inducible promoters suffer from slow induction kinetics, limited control of expression levels and/or a requirement for defined growth medium. In particular, no S. pombe inducible promoter systems exhibit a linear dose response, which would allow expression to be tuned to specific levels. We have adapted a fast, orthogonal promoter system with a large dynamic range and a linear dose response, based on β-estradiol-regulated function of the human estrogen receptor, for use in S. pombe. We show that this promoter system, termed Z3EV, turns on quickly, can reach a maximal induction of 20 fold, and exhibits a linear dose response over its entire induction range, with few off target effects. We demonstrate the utility of this system by regulating the mitotic inhibitor Wee1 to create a strain in which cell size is regulated by β-estradiol concentration. This promoter system will be of great utility for experimentally regulating gene expression in fission yeast

    An Electromyographic lnvestigation of the Quadriceps Muscles During the Performance of Multiple Angle Isometric Exercises

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    In clinical practice, physical therapists often employ various forms of quadriceps strengthening exercise to target the vastus medialis oblique (VMO) and the vastus medialis (VM) component of the quadriceps muscle. These strengthening exercises usually consist of multiple angle isometrics (MAI) performed throughout the range from 0°to 120°knee flexion. There is no evidence that any of these exercises is able to selectively target the individual component of the quadriceps muscle group. The aim of this study is to provide electromyographic evidence of quadriceps muscle selectivity during the performance of MAI exercise. Eleven subjects (7 females and 4 males) participated in this study. The mean age of subjects was 19.36+1.43 years, and the mean weight was 53.00+5.16 kg. Ag/AgCI surface electrodes were attached to the subjects' thigh, at sites corresponding to the vastus lateralis (VL), VM, VMO, and the rectus femoris (RF). Subjects were asked to perform isometric knee extension excrcises at 7 positions corresponding to 20°,30°,45°,60°,75°,90°,and 110°knee flexion. Each exercise was performed for 3 repetitions : with a 5-seconds hold period, and a rest interval of 30 seconds. The order of exercise was randomized. The raw EMG data was processed using a Butterworth band pass filter (10 to 240 Hz), rectified and integrated (IEMG). The IEMG data was analyzed using a paired T test. The level of significance was set at 0.05. In general, the results showed that the mean IEMG of the RF, VMO and VL increased as knee flexion angle increased while the mean IEMG of the VMO remained relatively unchanged throughout the tested range. The VM/VL ratio decreased, while the VMO/VL ratio increased as knee flexion angle increased. These results demonstrate that it is possible to selectively exercise the different components of the quadriceps muscles using multiple angle isometric exercises between 20°and 110°knee flexion.Article紀要 25: 1-9(2000)departmental bulletin pape

    Predicting the Route of Delivery in Women with Low-Lying Placenta Using Transvaginal Ultrasonography: Significance of Placental Migration and Marginal Sinus

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    Background/Aims: To examine the significance of placental migration and the presence of a placental marginal sinus to predict the eventual route of delivery in low-lying placenta. Methods: 49 women with a low-lying placenta after 30 weeks' gestation were studied. The distance between the internal os and leading edge of the placenta was measured weekly using transvaginal ultrasonography until 37 weeks' gestation. The relationship between the rate of placental migration, the presence of a placental marginal sinus and the eventual mode of delivery was investigated. Results: Although the cesarean section rate was 56.3% (9/16) in the 'slow' migration (0-2.0 mm/week) group, no patient (0/33) in the 'fast' (>2.0 mm/week) migration group underwent a cesarean section (p<0.01). The cesarean section rate was 71.4% (5/7) in patients with a placental marginal sinus, significantly greater than the rate of 9.5% (4/42) in patients without a marginal sinus (p<0.01). Conclusion:A decreased rate of placental migration until 37 weeks' gestation and the presence of a placental marginal sinus were associated with subsequent cesarean delivery because of antepartum vaginal bleeding. These parameters may be useful for predicting the route of delivery in women with a low-lying placenta.ArticleGYNECOLOGIC AND OBSTETRIC INVESTIGATION. 73(3):217-222 (2012)journal articl

    Placental Mesenchymal Dysplasia: Chronological Observation of Placental Images during Gestation and Review of the Literature

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    Placental mesenchymal dysplasia (PMD) is characterized by multiple hypoechoic vesicles which are similar to molar changes in the placenta; however, the process of such morphological changes of PMD during pregnancy has not been fully understood. We performed a review of all PMD cases published in English and identified 49 articles including 110 cases. With regard to the gestational age at which the multicystic pattern was seen, approximately 70% of cases were diagnosed at 13-20 weeks of gestation. Another characteristic feature of PMD is varicose dilation of fetal chorionic vessels. As many as 90% of cases were diagnosed as placenta with dilated fetal chorionic vessels in the third trimester. We also report a case of PMD which was found at 10 weeks of gestation according to ultrasonic molar patterns. Serial observations of the placenta using ultrasound and magnetic resonance imaging revealed that multicystic lesions became smaller after 23 weeks. In contrast, dilated placental vessels on the fetal side became apparent at 38 weeks. The present review highlights that placental vesicular lesions of PMD may precede dilation of fetal chorionic vessels during pregnancy. It also indicates the potential of a gradual reduction in size of PMD's placental vesicular lesions by serial study of placental images.ArticleGYNECOLOGIC AND OBSTETRIC INVESTIGATION. 75(4):217-223 (2013)journal articl
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