Influence of gas environment and heating on atomic structures of platinum nanoparticle catalysts for proton-exchange membrane fuel cells

Atomic-scale relaxations of platinum nanoparticles (Pt NPs) for fuel-cell catalysts are evaluated by spherical-aberration corrected environmental transmission electron microscopy (ETEM) under reference high-vacuum and N2 atmospheres, and then under reactive H2, CO and O2 atmospheres, combined with ex situ durability test using an electrochemical half-cell. In high-vacuum, increasing roughness due to continuous relaxation of surface-adsorbed Pt atoms is quantified in real-space. Under H2 and N2 atmospheres at a critical partial pressure of 1 × 10-2 Pa the stability of the surface facets is for the first time found to be improved. The adsorption behaviour of CO molecules is investigated using experimentally measured Pt-Pt bond lengths on the topmost surface layer of Pt NPs. The deactivation of Pt NPs in the anode environment of a proton-exchange-membrane fuel-cell is demonstrated at the atomic-scale in the ETEM, and the transformation of NPs into disordered nanoclusters is systematically quantified using the partial size distribution of Pt atomic clusters under controlled heating experiments at 423, 573 and 723 K

Establishment of Mouse Embryonic Stem Cell-Derived Erythroid Progenitor Cell Lines Able to Produce Functional Red Blood Cells

BACKGROUND: The supply of transfusable red blood cells (RBCs) is not sufficient in many countries. If erythroid cell lines able to produce transfusable RBCs in vitro were established, they would be valuable resources. However, such cell lines have not been established. To evaluate the feasibility of establishing useful erythroid cell lines, we attempted to establish such cell lines from mouse embryonic stem (ES) cells. METHODOLOGY/PRINCIPAL FINDINGS: We developed a robust method to obtain differentiated cell lines following the induction of hematopoietic differentiation of mouse ES cells and established five independent hematopoietic cell lines using the method. Three of these lines exhibited characteristics of erythroid cells. Although their precise characteristics varied, each of these lines could differentiate in vitro into more mature erythroid cells, including enucleated RBCs. Following transplantation of these erythroid cells into mice suffering from acute anemia, the cells proliferated transiently, subsequently differentiated into functional RBCs, and significantly ameliorated the acute anemia. In addition, we did not observe formation of any tumors following transplantation of these cells. CONCLUSION/SIGNIFICANCE: To the best of our knowledge, this is the first report to show the feasibility of establishing erythroid cell lines able to produce mature RBCs. Considering the number of human ES cell lines that have been established so far, the intensive testing of a number of these lines for erythroid potential may allow the establishment of human erythroid cell lines similar to the mouse erythroid cell lines described here. In addition, our results strongly suggest the possibility of establishing useful cell lines committed to specific lineages other than hematopoietic progenitors from human ES cells

Atomic force microscopy study of the growth and annealing of Ge islands on Si(100)

This is the publisher's version, also available electronically from http://scitation.aip.org/content/avs/journal/jvstb/20/2/10.1116/1.1459724.Atomic force microscopy is used to study the growth and annealing of Ge islands on Si(100) by molecular beam epitaxy. The Ge island shape, size distribution, number density, and spatial distribution under various growth conditions, such as different substrate temperatures, Ge beam fluxes, and annealing times, are investigated. By limiting the growth to a low coverage of 6 ML of Ge, we find that either a low growth temperature (⩽875 K) or a high beam flux can produce films dominated by pyramids of {105} facets. Domes of higher aspect ratios only appear at high growth temperatures or after a long time of annealing at low temperatures. This indicates that in the competition between the different kinetic processes responsible for the pyramid and dome formation, the domes require a higher activation energy and grow slower. We also demonstrate that appropriate annealing at low temperature can form locally ordered arrays of pyramids with a narrow size distribution

“The Good into the Pot, the Bad into the Crop!”—A New Technology to Free Stem Cells from Feeder Cells

A variety of embryonic and adult stem cell lines require an intial co-culturing with feeder cells for non-differentiated growth, self renewal and maintenance of pluripotency. However for many downstream ES cell applications the feeder cells have to be considered contaminations that might interfere not just with the analysis of experimental data but also with clinical application and tissue engineering approaches. Here we introduce a novel technique that allows for the selection of pure feeder-freed stem cells, following stem cell proliferation on feeder cell layers. Complete and reproducible separation of feeder and embryonic stem cells was accomplished by adaptation of an automated cell selection system that resulted in the aspiration of distinct cell colonies or fraction of colonies according to predefined physical parameters. Analyzing neuronal differentiation we demonstrated feeder-freed stem cells to exhibit differentiation potentials comparable to embryonic stem cells differentiated under standard conditions. However, embryoid body growth as well as differentiation of stem cells into cardiomyocytes was significantly enhanced in feeder-freed cells, indicating a feeder cell dependent modulation of lineage differentiation during early embryoid body development. These findings underline the necessity to separate stem and feeder cells before the initiation of in vitro differentiation. The complete separation of stem and feeder cells by this new technology results in pure stem cell populations for translational approaches. Furthermore, a more detailed analysis of the effect of feeder cells on stem cell differentiation is now possible, that might facilitate the identification and development of new optimized human or genetically modified feeder cell lines

Translation and validation of the Japanese version of the Birth Satisfaction Scale-Revised

Aim: This study aimed to develop a Japanese version of the Birth Satisfaction Scale-Revised and evaluate its reliability and validity.Methods: After translating the Birth Satisfaction Scale-Revised into Japanese, we conducted an Internet-based cross-sectional study with 445 Japanesespeaking women within 2 months of childbirth. Of these, 98 participated in the retest 1 month later. Data were analyzed using the COSMIN study design checklist for patient-reported outcome measurement instruments. Content validity was evaluated through cognitive debriefing during the translation process into Japanese. Confirmatory factor analysis was conducted to verify structural and cross-cultural validities. For hypothesis testing, we tested correlations with existing measures for convergent and divergent validities, and for known-group discriminant validity, we made comparisons between types of childbirth. Internal consistency was calculated using Cronbach's α, and test–retest reliability was evaluated using the intraclass correlation coefficient.Results: For the Japanese-Birth Satisfaction Scale-Revised, the established threefactor model fit poorly, whereas the four-factor model fit better. Full metric invariance was observed in both the nulliparous and multiparous groups. Good convergent, divergent, and known-group discriminant validities and test–retest reliability were established. Internal consistency observations were suboptimal; however for vaginal childbirth, the Cronbach's α of the total score was .71.Conclusions: The Japanese-Birth Satisfaction Scale-Revised is a valid and reliable scale, with the exception of internal consistency that requires further investigation. If limited to vaginal childbirth, research, clinical applications, and international comparisons can be drawn

Response to ‘Hydration increases cell metabolism’

Letter to the editor ‘Hydration increases cell metabolism’ by S N Thornton, P C Even and G van Dijk in the same publication

Semi-Automated Biomarker Discovery from Pharmacodynamic Effects on EEG in ADHD Rodent Models

Abstract We propose a novel semi-automatic approach to design biomarkers for capturing pharmacodynamic effects induced by pharmacological agents on the spectral power of electroencephalography (EEG) recordings. We apply this methodology to investigate the pharmacodynamic effects of methylphenidate (MPH) and atomoxetine (ATX) on attention deficit/hyperactivity disorder (ADHD), using rodent models. We inject the two agents into the spontaneously hypertensive rat (SHR) model of ADHD, the Wistar-Kyoto rat (WKY), and the Wistar rat (WIS), and record their EEG patterns. To assess individual EEG patterns quantitatively, we use an integrated methodological approach, which consists of calculating the mean, slope and intercept parameters of temporal records of EEG spectral power using a smoothing filter, outlier truncation, and linear regression. We apply Fisher discriminant analysis (FDA) to identify dominant discriminants to be heuristically consolidated into several new composite biomarkers. Results of the analysis of variance (ANOVA) and t-test show benefits in pharmacodynamic parameters, especially the slope parameter. Composite biomarker evaluation confirms their validity for genetic model stratification and the effects of the pharmacological agents used. The methodology proposed is of generic use as an approach to investigating thoroughly the dynamics of the EEG spectral power