bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Role of Water in Aqueous Ruthenium‐Catalyzed Transfer Hydrogenation of Ketones.
Authors: Pavlova Anna , Meijer Evert Jan 
Published: August 2012

AbstractWe report an accurate computational study of the role of water in transfer hydrogenation of formaldehyde with a ruthenium‐based catalyst using a water‐specific model. Our results suggest that the reaction mechanism in aqueous solution is significantly different from that in the gas phase or in methanol solution. Previous theoretical studies have shown a concerted hydride and proton transfer in the gas phase (M. Yamakawa, H. Ito, R. Noyori, J. Am. Chem. Soc. 2000, 122, 1466–1478;J.‐W. Handgraaf, J. N. H. Reek, E. J. Meijer, Organometallics 2003, 22, 3150–3157; D. A. Alonso, P. Brandt, S. J. M. Nordin, P. G. Andersson, J. Am. Chem. Soc. 1999, 121, 9580–9588; D. G. I. Petra, J. N. H. Reek, J.‐W. Handgraaf, E. J. Meijer, P. Dierkes, P. C. J. Kamer, J. Brussee, H. E. Schoemaker, P. W. N. M. van Leeuwen, Chem. Eur. J. 2000, 6, 2818–2829), whereas a delayed, solvent‐mediated proton transfer has been observed in methanol solution (J.‐W. Handgraaf, E. J. Meijer, J. Am. Chem. Soc. 2007, 129, 3099–3103). In aqueous solution, a concerted transition state is observed, as in the previous studies. However, only the hydride is transferred at that point, whereas the proton is transferred later by a water molecule instead of the catalyst.
Phase Transition of a Cobalt‐Free Perovskite as a High‐Performance Cathode for Intermediate‐Temperature Solid Oxide Fuel Cells
Authors: Jiang Shanshan , Zhou Wei , Niu Yingjie , Zhu Zhonghua , Shao Zongping 
Published: August 2012

AbstractIt is generally recognized that the phase transition of a perovskite may be detrimental to the connection between cathode and electrolyte. Moreover, certain phase transitions may induce the formation of poor electronic and ionic conducting phase(s), thereby lowering the electrochemical performance of the cathode. Here, we present a study on the phase transition of a cobalt‐free perovskite (SrNb0.1Fe0.9O3−δ, SNF) and evaluate its effect on the electrochemical performance of the fuel cell. SNF exists as a primitive perovskite structure with space group P4mm (99) at room temperature. As evidenced by in situ high‐temperature X‐ray diffraction measurements over the temperature range of 600 to 1000 °C, SNF undergoes a transformation to a tetragonal structure with a space group I4/m (87). This phase transition is accompanied by a moderate change in the volume, allowing a good cathode/electrolyte interface on thermal cycling. According to the electrochemical impedance spectroscopy evaluation, the I4/m phase exhibits positive effects on the cathode’s performance, showing the highest oxygen reduction reaction activity of cobalt‐free cathodes reported so far. This activity improvement is attributed to enhanced oxygen surface processes.
Space vector pulse‐width modulation theory and solution for Z‐source inverters with maximum constant boost control
Authors: Yu Kun , Luo Fang Lin , Zhu Miao , Cai Xu 
Published: August 2012

SUMMARYThe theory of space vector pulse‐width modulation (SVPWM) technique for the three‐phase Z‐source inverter has been introduced in detail, and a novel implementation scheme based on the maximum constant boost control method is presented in this paper. Like the traditional carrier‐based maximum constant boost control strategy, the proposed control method is able to achieve the maximum voltage boost ability while always keeping the shoot‐through duty ratio constant. Besides, it inherits the advantages from the SVPWM technique. Compared with carrier‐based strategies, it has wider linear operation range and is easier for digital implementation. The number of switching transition in each switching cycle is reduced, which significantly decreases switching losses. To investigate the advantages of lessening switching losses, three optimal switching patterns are proposed and compared with the carrier‐based strategy. It is demonstrated that the number of switching transition can be reduced by 60% at most by the proposed SVPWM‐based control method. All the theoretical analysis has been validated by the simulation results in MATLAB/Simulink at last. Copyright © 2012 John Wiley & Sons, Ltd.
Biotic controls on shallow translational landslides
Authors: Vorpahl Peter , Dislich Claudia , Elsenbeer Helmut , Märker Michael , Schröder Boris 
Published: August 2012

ABSTRACTIn undisturbed tropical montane rainforests massive organic layers accommodate the majority of roots and only a small fraction of roots penetrate the mineral soil. We investigated the contribution of vegetation to slope stability in such environments by modifying a standard model for slope stability to include an organic layer with distinct mechanical properties. The importance of individual model parameters was evaluated using detailed measurements of soil and vegetation properties to reproduce the observed depth of 11 shallow landslides in the Andes of southern Ecuador. By distinguishing mineral soil, organic layer and above‐ground biomass, it is shown that in this environment vegetation provides a destabilizing effect mainly due to its contribution to the mass of the organic layer (up to 973 t ha− 1under wet conditions). Sensitivity analysis shows that the destabilizing effect of the mass of soil and vegetation can only be effective on slopes steeper than 37.9°. This situation applies to 36% of the study area. Thus, on the steep slopes of this megadiverse ecosystem, the mass of the growing forest promotes landsliding, which in turn promotes a new cycle of succession. This feedback mechanism is worth consideration in further investigations of the impact of landslides on plant diversity in similar environments. Copyright © 2012 John Wiley & Sons, Ltd.
Regulation of microglia development and homeostasis
Authors: Greter Melanie , Merad Miriam 
Published: August 2012

AbstractMicroglia represent the resident macrophages of the central nervous system (CNS) and account for 10% of the adult glial cell population in the normal brain. Although microglial cells are thought to contribute to most pathological conditions including CNS infections, neuroinflammatory lesions, brain tumors, and neurodegenerative diseases, their exact role in CNS development, homeostasis, and disease remains poorly understood. In contrast to most macrophage populations, microglia survive high‐dose ionizing radiation and maintain themselves locally and independently of circulating precursors in the steady state. However, controversies remain on the origin of microglia in the brain and whether they could potentially be repopulated by circulating myeloid precursors after brain injury. Microglia‐targeted therapies through the use of genetically modified circulating hematopoietic cells proved to be a promising therapeutic strategy for the treatment of brain diseases. It is thus of great importance to understand the contribution and developmental cues of circulating myeloid cells as potential microglia progenitors to the adult pool of microglia in the steady state and under inflammatory conditions. © 2012 Wiley Periodicals, Inc.
Exploiting stem cell therapy: The 3rd meeting of stem cell research Italy
Authors: Di Bernardo Giovanni , Piva Roberta , Giordano Antonio , Galderisi Umberto 
Published: August 2012

AbstractThe study of stem cells is one of the most exciting areas of contemporary biomedical research. During the 3rd Joint Meeting of Stem Cell Research Italy (June 2012, Ferrara, Italy), scientists from different multidisciplinary areas explored new frontiers of basic and applied stem cell research with key lectures and oral presentations. There was a public debate on ethics during the opening ceremony, specifically on the limits and potentialities of adult and embryonic stem cells. Some scientists presented basic research data showing evolutionary aspects, which could be of interest in understanding specific biological phenomena. Others focused on “dangerous liaisons” between gene transfer vectors and the human genome. Some speakers provided insight into current stem cell therapies, such as those involving human epithelial stem cells for treatment of skin diseases. Other researchers presented data on close‐to‐therapy findings, such as the use of mesenchymal stem cells in brain repair. Of note, during the meeting, spotlights were focused on major issues that have to be considered for GMP stem cell production for cell therapy. In “Meet the Expert” sessions, specialists presented innovative technologies such as a next‐generation sequencing system. Finally, the meeting provided an excellent opportunity for young scientists to show their findings, and to discuss with each other and with internationally recognized experts. J. Cell. Physiol. 228: 911–914, 2013. © 2012 Wiley Periodicals, Inc.
Detecting and estimating density dependence in wildlife populations
Authors: Lebreton Jean‐Dominique , Gimenez Olivier 
Published: August 2012

AbstractWe review methods for detecting and assessing the strength of density dependence based on 2 types of approaches: surveys of population size and studies of life history traits, in particular demographic parameters. For the first type of studies, methods neglecting uncertainty in population size should definitely be abandoned. Bayesian approaches to simple state‐space models accounting for uncertainty in population size are recommended, with some caution because of numerical difficulties and risks of model misspecification. Realistic state‐space models incorporating features such as environmental covariates, age structure, etc., may lack power because of the shortness of the time series and the simultaneous presence of process and sampling variability. In all cases, complementing the population survey data with some external information, with priority on the intrinsic growth rate, is highly recommended. Methods for detecting density dependence in life history traits are generally conservative (i.e., tend to underestimate the strength of density dependence). Among approaches to correct for this effect, the state‐space formulation of capture–recapture models is again the most promising. Foreseeable developments will exploit integrated monitoring combining population size surveys and individual longitudinal data in refined state‐space models, for which a Bayesian approach is the most straightforward statistical treatment. One may thus expect an integration of various types of models that will make it possible to look at density dependence as a complex biological process interacting with other processes rather than in terms of a simple equation; modern statistical and modeling tools make such a synthesis within reach. © 2012 The Wildlife Society.
Small sample bias in dynamic occupancy models
Authors: Mckann Patrick C. , Gray Brian R. , Thogmartin Wayne E. 
Published: August 2012

AbstractOccupancy models may be used to estimate the probability that a randomly selected site in an area of interest is occupied by a species (ψ), given imperfect detection (p). This method can be extended, given multiple survey periods, to permit the estimation of seasonal probabilities of ψ, colonization (γ), persistence (φ), and extinction (1 − φ) in season t. We evaluated the sampling properties of estimators of these parameters using simulated data across a range of the parameters, differing levels of sites and visits, with a published dynamic occupancy model (Royle and Kery 2007). Bias depended largely on p and the number of visits, but also on the number of sites, ψt, γ, and 1 − φ. To decrease bias in all parameters to near zero, our results suggest that the number of required visits will depend on p, such that the probability of detection at an occupied site is near 0.9, and the required number of sites will be near 60 for ψt estimation and 120 or greater for γ and 1 − φ estimation. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Effects of predator exclusion on nest and hatchling survival in the gopher tortoise
Authors: Smith Lora L. , Steen David A. , Conner L. Mike , Rutledge Jessica C. 
Published: August 2012

AbstractGopher tortoise (Gopherus polyphemus) populations are declining throughout the Southeast, and high levels of predation on nests and juveniles have been suggested as a potential contributor to this decline. Therefore, we documented gopher tortoise nest success and hatchling survival relative to mammalian predator control. We used 4, large (approx. 40‐ha) fenced, predator exclosures to exclude mid‐sized mammalian predators: bobcat (Lynx rufus), raccoon (Procyon lotor), Virginia opossum (Didelphis virginianus), fox (Urocyon cinereoargenteusandVulpes vulpes), coyote (Canis latrans), nine‐banded armadillo (Dasypus novemcinctus), and skunk (Mephitis mephitis); 4 unfenced plots served as controls. We monitored nests for survival through hatching and used radio‐telemetry to examine hatchling survival. We radio‐tracked 40 hatchlings for up to 329 days, but we were only able to track 8 individuals from a single nest at an unfenced plot because of high nest predation. Mean nest survival was greater at exclosures than at unfenced controls (F1, 2 = 45.80,P = 0.0001). Hatchling survival differed (χ2 = 5.839,P = 0.016) between unfenced plots (37.5%) and exclosures (74.4%), suggesting that mammals also were significant predators of hatchlings. The number of juvenile (<13 cm in diameter) and subadult tortoise burrows (13–21.9 cm) increased over a 6‐year period in exclosures, providing further support for an effect of excluding mammalian predators on nest and juvenile tortoise survival. © 2012 The Wildlife Society.
Hydrogel Substrate Stiffness and Topography Interact to Induce Contact Guidance in Cardiac Fibroblasts
Authors: Al‐Haque Shahed , Miklas Jason W. , Feric Nicole , Chiu Loraine L. Y. , Chen Wen Li Kelly , Simmons Craig A. , Radisic Milica 
Published: August 2012

AbstractPrevious studies demonstrated the importance of substrate stiffness and topography on the phenotype of many different cell types including fibroblasts. Yet the interaction of these two physical parameters remains insufficiently characterized, in particular for cardiac fibroblasts. Most studies focusing on contact guidance use rigid patterned substrates. It is not known how the ability of cardiac fibroblasts to follow grooves and ridges changes as the substrate stiffness is decreased to match the range of stiffness found in native heart tissues. This report demonstrates a significant interactive effect of substrate stiffness and topography on cardiac fibroblast elongation and orientation using polyacrylamide substrates of different stiffness and topography. magnified image
Non‐Adhesive Behavior of New Nanostructured PNIPAM Surfaces Towards Specific Neurodegenerative Proteins: Application to Storage and Titration of Tau Proteins
Authors: Vrlinic Tjasa , Debarnot Dominique , Legeay Gilbert , Coudreuse Arnaud , El Moualij Benaissa , Zorzi Willy , Perret‐Liaudet Armand , Quadrio Isabelle , Mozetic Miran , Poncin‐Epaillard Fabienne 
Published: August 2012

AbstractNew nonfouling tubes are developed and their influence on the adhesion of neuroproteins is studied. The biomarkers are considered as single components (recombinant prion and Tau proteins) or in a solution of native and pathological forms. The samples are stored for 24 h at 4 °C in virgin and treated tubes layered with two different nanostructured coatings based on poly(N‐isopropylacrylamide) with either a positive or a neutral charge, and the protein adhesion is monitored. The recombinant protein with a high pI is repelled from the nanostructured surface that has a negative ζ potential, whereas the recombinant protein with the lower pI is attracted. Furthermore, in the case of complex solutions, neutral nanostructured surfaces are able to retain all amyloid biomarkers. magnified image
Enhancing Specific Binding of L929 Fibroblasts: Effects of Multi‐Scale Topography of GRGDY Peptide Modified Surfaces
Authors: Zhou Feng , Li Dan , Wu Zhaoqiang , Song Bo , Yuan Lin , Chen Hong 
Published: August 2012

AbstractSurface chemical composition and roughness caused by micro/nano‐topographical structures are two predominant factors in determining cellular response. A series of gold nanoparticle layers (GNPLs) with increasing surface roughness are prepared by depositing gold nanoparticles onto planar gold films. Glycine‐arginine‐glycine‐aspartic acid‐tyrosine (GRGDY) peptide is then conjugated to the surface through poly[oligo(ethylene glycol) methacrylate] polymer brushes as spacers. The pristine micro/nano‐roughness structures significantly inhibit L929 cell growth. After modification with POEGMA‐GRGDY, however, the micro/nano‐structures greatly enhance L929 cell‐specific interactions while maintaining superior low‐fouling ability compared to planar gold. magnified image
Monomers for Adhesive Polymers, 9–Synthesis, Radical Photopolymerization, and Properties of (Meth)acrylamido Dihydrogen Phosphates
Authors: Moszner Norbert , Angermann Jörg , Fischer Urs , Bock Thorsten 
Published: August 2012

Abstract5‐Methacrylamidopentyl (3a), 10‐(N‐methylacrylamido)decyl (3b), or 11‐(N‐methylacrylamido)undecyl dihydrogen phosphate (3c) are synthesized by (meth)acrylation of the corresponding ω‐aminoalkane‐1‐ols with methacrylic anhydrid or acryloyl chloride followed by phosphorylation of the formed ω‐(meth)acrylamidoalkane‐1‐ols. The monomers show a significantly improved hydrolytic stability compared to the corresponding methacrylate‐based dihydrogen phosphates. The photopolymerization of 3a–c with a bis(acrylamide) crosslinker confirms a high reactivity in the free‐radical copolymerization. These monomers enable the mediation of a strong bond between the enamel or dentin surface and a restorative composite under self‐etching conditions. magnified image
The autophagy protein LC3A correlates with hypoxia and is a prognostic marker of patient survival in clear cell ovarian cancer
Authors: Spowart Jaeline E , Townsend Katelin N , Huwait Hassan , Eshragh Sima , West Nathan R , Ries Jenna N , Kalloger Steve , Anglesio Michael , Gorski Sharon M , Watson Peter H , Gilks C Blake , Huntsman David G , Lum Julian J 
Published: August 2012

AbstractClear cell ovarian cancer histotypes exhibit metabolic features associated with resistance to hypoxia and glucose deprivation‐induced cell death. This metabolic characteristic suggests that clear cell ovarian cancers activate survival mechanisms not typical of other epithelial ovarian cancers. Here we demonstrate that microtubule‐associated protein 1 light chain 3A (LC3A), a marker of autophagy, is related to hypoxia and poor prognosis in clear cell ovarian cancer. In 485 ovarian tumours, we found that LC3A was significantly associated with poor progression‐free (p = 0.0232), disease‐specific (p = 0.0011) and overall patient survival (p = 0.0013) in clear cell ovarian cancer patients, but not in other subtypes examined. LC3A was an independent prognostic marker of reduced disease‐specific [hazard ratio (HR): 2.55 (95% CI 1.21–5.37); p = 0.014] and overall survival [HR: 1.95 (95% CI 1.00–3.77); p = 0.049] in patients with clear cell ovarian carcinoma. We also found a strong link between autophagy and hypoxia as LC3A staining revealed a significant positive association with the hypoxia‐related proteins carbonic anhydrase‐IX and HIF‐1α. The functional link between hypoxia and autophagy was demonstrated using clear cell and high‐grade serous cell lines that were subjected to hypoxia or hypoxia + glucose deprivation. Clear cell carcinoma lines displayed greater autophagy induction and were subsequently more sensitive to inhibition of autophagy under hypoxia compared to the high‐grade serous lines. Together, our findings indicate that hypoxia‐induced autophagy may be crucial to the clinical pathology of clear cell ovarian cancer and is a potential explanation for histological subtype differences in patient disease progression and outcomes. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Effect of window layer composition in Cd1−xZnxS/CdTe solar cells
Authors: Kartopu Giray , Clayton Andrew J. , Brooks William S.M. , Hodgson Simon D. , Barrioz Vincent , Maertens Alban , Lamb Dan A. , Irvine Stuart J.C. 
Published: August 2012

ABSTRACTTo improve CdS/CdTe cell/module efficiencies, CdS window layer thinning is commonly applied despite the risk of increased pin‐hole defects and shunting. An alternative approach is to widen the band gap of the window layer (2.42 eV for CdS) via alloying, for example, by forming compositions of Cd1−xZnxS. In this study, the performance of Cd1−xZnxS/CdTe thin‐film solar cells has been studied as a function of x (from x = 0 to 0.9), widening the window layer band gap up to and over 3.4 eV. Optimum Cd1−xZnxS compositions were clearly identified to be around x = 0.7, and limitations to the achievable photocurrent and conversion efficiencies have been addressed. Copyright © 2012 John Wiley & Sons, Ltd.
Structural analyses of seeded thin film microcrystalline silicon solar cell
Authors: Agbo S. N. , Dobrovolskiy S. , Wegh G. , van Swaaij R. A. C. M. M. , Tichelaar F. D. , Sutta P. , Zeman M. 
Published: August 2012

ABSTRACTThis contribution investigates the effect of seeding the growth of thin film microcrystalline silicon (µc‐Si : H) deposited by radio frequency plasma‐enhanced chemical vapor deposition on the material properties of µc‐Si : H film and the device performance of p‐i‐n and n‐i‐p µc‐Si : H solar cells. By means of Raman measurement, x‐ray diffraction (XRD) and transmission electron microscopy (TEM), we investigate the structure of seeded µc‐Si : H. In particular, the effect of seed layers on the crystallinity development is investigated. Measurements of the depth profile of the crystalline mass fraction using Raman spectroscopy show that seed layers lead to a more rapid and uniform crystallinity development in growth direction. The amorphous incubation layer is suppressed and crystallization begins directly from onset of film growth without evolving through the intermediate growth phases. From TEM analyses, we observe that crystal sizes are not affected by seed layers. Horizontal cracks are however observed to dominate the early growth of µc‐Si : H in p‐i‐n solar cell and this is reduced upon seeding. For the n‐i‐p cells, these cracks are not affected by seeding. XRD results also indicate that the use of seed layers does not affect the crystal sizes but affects the direction of preferential orientation. Solar cell external parameters show that seeding of p‐i‐n solar cells leads mainly to increase in short‐circuit current density, Jsc with a slight drop in open‐circuit voltage, Voc. For the n‐i‐p cells, a reverse effect is observed. In this case, the Voc increases and the Jsc decreases. Copyright © 2012 John Wiley & Sons, Ltd.