bluuebunny/crossref_metadata_2025_split huggingface dataset:
Slow geminate‐charge‐pair recombination dynamics at polymer: Fullerene heterojunctions in efficient organic solar cells
Authors: Provencher Françoise , Sakowicz Maciej , Brosseau Colin‐Nadeau , Latini Gianluca , Beaupré Serge , Leclerc Mario , Reynolds Luke X. , Haque Saif A. , Leonelli Richard , Silva Carlos 
Published: August 2012

AbstractWe explore charge recombination dynamics at electron donor‐acceptor heterojunctions, formed between a semiconductor polymer (PCDTBT) and a fullerene derivative (PC70BM), by means of combined time‐resolved photoluminescence and transient absorption spectroscopies. Following prompt exciton dissociation across the heterojunction, a subset of bound electron‐hole pairs recombines with a temperature‐independent rate distribution spanning submicrosecond timescales to produce luminescent charge‐transfer excitons (CTX). At 14 K, this slow mechanism is the dominant geminate charge recombination pathway, whereas we also observe CTX emission on subnanosecond timescales at 293 K. We thus find that at these temperatures, a fraction of the initial charge‐pair population is trapped deeply such that they only recombine slowly over a broad distribution of timescales by quantum tunneling. We identify geminate polaron pairs (GPP) as a reservoir of long‐lived localized states that repopulate the CTX up to microsecond timescales. The observation of such distributed geminate‐charge recombination highlights the importance of the molecular nature of specific donor–acceptor electronic interactions in defining the relaxation pathways of trapped GPP. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Effects of water freezing on the mechanical properties of nafion membranes
Authors: Teocoli Francesca , Paolone Annalisa , Palumbo Oriele , Navarra Maria Assunta , Casciola Mario , Donnadio Anna 
Published: August 2012

AbstractMost of the research efforts on Nafion have been devoted to the study of the perfluorinated ionomer membranes at optimal conditions for the desired applications, such as high temperature and low relative humidity for polymer electrolyte membrane fuel cells (PEM FC). In view of the possible changes induced by the freezing of water in the structure of Nafion and considering that in cold start conditions of a PEM FC device, Nafion needs to work also below 273 K, we measured the Young's modulus (Y) and the elastic energy dissipation (tan δ) in the temperature range between 90 and 470 K and the stress–strain curves between 300 and 173 K. The measurements reported here indicate that the mechanical properties of wet Nafion membrane change dramatically with temperature, that is, from a rubber‐like behavior at room temperature to a brittle behavior below 180 K. Moreover, we observed that the freezing of the nanoconfined water is complete only below 180 K, as indicated by a large increase of the Young's modulus. Between 180 and 300 K, the large values of tan δ suggest the occurrence of friction between the liquid water bound to the walls of the hydrophilic domains and the solid ice residing in the center of channels. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
The Effect of Applied Electric Field on the Diameter and Size Distribution of Electrospun Nylon6 Nanofibers
Authors: Sohrabi Amirreza , Shaibani Parmiss Mojir , Thundat Thomas 
Published: August 2012

SummaryOne‐dimensional Nylon6 nanofibers were fabricated through the electrospinning process. The effect of the applied electric field and voltage–distance combinations on the diameter and size distribution of the fibers was examined systematically by analyzing scanning electron microscopy (SEM) images. The results indicated that maintaining the electric field at 1 kV/cm with the voltage–distance combination of 15 kV–15 cm among all other combinations would result in the optimum average diameter as well as a narrow size distribution of the fibers. SCANNING 35: 183‐188, 2013. © 2012 Wiley Periodicals, Inc.
Runx3 Protects Gastric Epithelial Cells Against Epithelial-Mesenchymal Transition-Induced Cellular Plasticity and Tumorigenicity
Authors: Voon Dominic Chih-Cheng , Wang Huajing , Koo Jason Kin Wai , Nguyen Tu Anh Pham , Hor Yit Teng , Chu Yeh-Shiu , Ito Kosei , Fukamachi Hiroshi , Chan Shing Leng , Thiery Jean Paul , Ito Yoshiaki 
Published: August 2012

Abstract
The transcription factor RUNX3 functions as a tumor suppressor in the gastrointestinal epithelium, where its loss is an early event in carcinogenesis. While RUNX3 acts concurrently as a mediator of TGF-β signaling and an antagonist of Wnt, the cellular changes that follow its loss and their contribution to tumorigenicity are not fully understood. Here, we report that the loss of Runx3 in gastric epithelial cells results in spontaneous epithelial-mesenchymal transition (EMT). This produces a tumorigenic stem cell-like subpopulation, which remarkably expresses the gastric stem cell marker Lgr5. This phenomenon is due to the compounding effects of the dysregulation of the TGF-β and Wnt pathways. Specifically, Runx3−/−p53−/− gastric epithelial cells were unexpectedly sensitized for TGF-β-induced EMT, during which the resultant induction of Lgr5 was enhanced by an aberrantly activated Wnt pathway. These data demonstrate a protective role for RUNX3 in safeguarding gastric epithelial cells against aberrant growth factor signaling and the resultant cellular plasticity and stemness.
A shRNA Functional Screen Reveals Nme6 and Nme7 Are Crucial for Embryonic Stem Cell Renewal
Authors: Wang Chia-Hui , Ma Nianhan , Lin Yu-Tsen , Wu Cheng-Chung , Hsiao Michael , Lu Frank Leigh , Yu Ching-Chia , Chen Shao-Yin , Lu Jean 
Published: August 2012

Abstract
In contrast to the somatic cells, embryonic stem cells (ESCs) are characterized by its immortalization ability, pluripotency, and oncogenicity. Revealing the underlying mechanism of ESC characteristics is important for the application of ESCs in clinical medicine. We performed systematic functional screen in mouse ESCs with 4,801 shRNAs that target 929 kinases and phosphatases. One hundred and thirty-two candidate genes that regulate both ESC expansion and stem cell marker expression were identified. Twenty-seven out of the 132 genes were regarded as most important since knockdown of each gene induces morphological changes from undifferentiated to differentiated state. Among the 27 genes, we chose nonmetastatic cell 6 (Nme6, also named as Nm23-H6) and nonmetastatic cell 7 (Nme7, also designated as Nm23-H7) to study first. Nme6 and Nme7 both belong to the members of nucleoside diphosphate kinase family. We demonstrate that Nme6 and Nme7 are important for the regulation of Oct4, Nanog, Klf4, c-Myc, telomerase, Dnmt3B, Sox2, and ERas expression. Either knockdown of Nme6 or Nme7 reduces the formation of embryoid body (EB) and teratoma. The overexpression of either Nme6 or Nme7 can rescue the stem cell marker expression and the EB formation in the absence of leukemia inhibiting factor. This implies the importance of Nme6 and Nme7 in ESC renewal. This finding not only pinpoints Nme6 or Nme7 can regulate several critical regulators in ESC renewal but also increases our understanding of the ESC renewal and oncogenesis.
Principles of nutrient management for sustainable forest bioenergy production
Authors: Mead Donald , Smith Charles 
Published: August 2012

AbstractNutrient management is an important part of ensuring sustainable forest production. Essential concepts for managing site nutrients are built on the knowledge of types of soil, tree nutrient demands, and how these are impacted by silviculture, harvesting, and other management practices. Managers must clearly define forest management objectives, and how bioenergy production or carbon dioxide‐offset objectives require special consideration. Managers must examine how silviculture, harvesting, and other management practices might affect nutrient pools and availability. Soil fertility management practices are designed in response to these evaluation steps. Fertility management alternatives may include altering management practices that affect the distribution of harvested tree branches, foliage, and tops, as well as addition of fertilizers, nitrogen‐fixing plants, or wood ash. Planting on sites with pre‐existing nutrient deficiencies may require adding nutrients to obtain merchantable tree growth over the short and long term. Nutrient management principles may also be required to minimize off‐site impacts of management practices, for example, on water quality or climate change. Managers must determine what nutrients are needed on forested sites, amendment rates, and timing, and take into account the relationships among nutrients, soil, climate, and plant processes throughout the rotation. Soil and foliar analysis and the use of soil and plant bioassay tools can assist in these evaluations. Sustainable management practices require that nutrient control strategies evaluate economic and energy balances, and if necessary, modify management practices, including nutrient amendments, to ensure that they are sustainable. Examples of forest nutrient management practices are described.This article is categorized under:Bioenergy > Systems and InfrastructureEnergy and Development > Science and MaterialsEnergy and Development > Economics and PolicyEnergy and Development > Climate and Environment
Opportunities and barriers of high‐voltage direct current grids: a state of the art analysis
Authors: Coll‐Mayor Debora , Schmid Jürgen 
Published: August 2012

AbstractLimiting the consequences of the climate change means that global CO2 emissions are to be reduced very rapidly. Taking into account that the expected economic growth of developing countries will inevitably be accompanied by a further growth in emissions in these countries, there is a strong necessity that the energy systems in the industrialized world be transformed into emission‐free ones. This level of reduction requires, for example, that the European Union achieves a ‘nearly zero‐carbon power supply’, involving replacing of fossil fuels in most or all buildings and much of the transport sector by nearly zero‐carbon electricity. It is also clear that the current political framework is, especially in Europe, propitiating the large‐scale implementation of renewable energy sources. In order to make this large implementation economically feasible, it is essential that the potential of these sources is maximized, placing them at sites providing the highest possible output. These sites are often located far away from consumption centers, making compulsory the transmission of large amounts of energy from generation to demand. In the global scenario, the necessary capacity of the power infrastructure for doing such exceeds by far the existing infrastructure and therefore new transmission capacity is necessary. Taking into account that large amounts of Renewable Energy Sources (RES) are to be integrated in the current power system and that most of the generation will take place at remote locations requiring new transmission assets, this article answers the question of whether a supergrid is necessary to enable this transformation.This article is categorized under:

Energy Infrastructure > Systems and Infrastructure
Energy Infrastructure > Climate and Environment
High efficiency photovoltaics: on the way to becoming a major electricity source
Authors: Wang Xiaoting , Byrne John , Kurdgelashvili Lado , Barnett Allen 
Published: August 2012

AbstractThe dramatic growth of the photovoltaic (PV) industry—accelerated by increased economies of scale, technology improvements, research and development efforts, and strong policy support—has pushed PV to set out on its pathway to becoming a major electricity source. The speed and course of this pathway will be determined by the development of PV energy price and its relation to market electricity sales price. The current gap between PV energy price and market electricity sales is often covered by substantial government subsidies. Using the United States PV market as a case study to illustrate the need for PV energy price decline, this article details the potential contribution of high‐efficiency PV based on different materials to realize such a decline and a substantial PV electricity share. It is found that—with considerable government support—PV's electricity share in the United States can rise to 25% by 2050. In order to help the PV industry achieve significant progress without large government subsidies, more radical decline of PV system cost is necessary. As such, quantitative analysis is deployed to investigate the value of module efficiency in lowering the total PV electricity cost through a levelized cost of energy analysis. Next, the article investigates in detail the research and development opportunities for high‐efficiency PV and projects the required efficiency‐price ranges for different types of PV modules.This article is categorized under:

Photovoltaics > Economics and Policy
Large‐scale wind deployment, social acceptance
Authors: Horbaty Robert , Huber Stefanie , Ellis Geraint 
Published: August 2012

AbstractThe public is typically in agreement with the renewable energy targets established in many national states and generally supports the idea of increased reliance on wind energy. Nevertheless, many specific wind power projects face significant local opposition. A key question for the wind energy sector is, therefore, how to better engage local people to foster support for specific projects. IEA Wind Task 28 on Social Acceptance of Wind Energy Projects aims to facilitate wind energy development by reviewing current practices, emerging ideas, and exchanging successful practices among the participating countries. It also aims to disseminate the insights of leading research to a nontechnical audience, including project developers, local planning officials, and the general public. The interdisciplinary approach adopted by Task 28 enables an in‐depth understanding of the nature of opposition to wind projects and a critical assessment of emerging strategies for social acceptance. Task 28 has analyzed a range of key issues related to social acceptance of wind energy, including the impacts on landscapes and ecosystems, on standard of living and well‐being, the implementation of energy policy and spatial planning, the distribution of costs and benefits, and procedural justice. It is clear that although wind energy has many benefits; however, specific projects do impact local communities. As such the concerns of the affected people have to be taken seriously. Moreover, as opposition is rarely without foundation, it is in the interests of developers and advocates to engage local people and to improve projects for the benefit of all.This article is categorized under:

Wind Power > Economics and Policy
Enhanced production of α-cyclodextrin glycosyltransferase in Escherichia coli by systematic codon usage optimization
Authors: Liu Hua , Li Jianghua , Du Guocheng , Zhou Jingwen , Chen Jian 
Published: August 2012

Abstract
Enhancing the production of α-cyclodextrin glycosyltransferase (α-CGTase) is a key aim in α-CGTase industries. Here, the mature α-cgt gene from Paenibacillus macerans JFB05-01 was redesigned with systematic codon optimization to preferentially match codon frequencies of Escherichia coli without altering the amino acid sequence. Following synthesis, codon-optimized α-cgt (coα-cgt) and wild-type α-cgt (wtα-cgt) genes were cloned into pET-20b(+) and expressed in E. coli BL21(DE3). The total protein yield of the synthetic gene was greater than wtα-cgt expression (1,710 mg L−1) by 2,520 mg L−1, with the extracellular enzyme activity being improved to 55.3 U mL−1 in flask fermentation. ΔG values at -3 to +50 of the pelB site of both genes were −19.10 kcal mol−1. Functionally, coα-CGTase was equally as effective as wtα-CGTase in forming α-cyclodextrin (α-CD). These findings suggest that preferred codon usage is advantageous for translational efficiency to increase protein expression. Finally, batch fermentation was applied, and the extracellular coα-CGTase enzyme activity was 326 % that of wtα-CGTase. The results suggest that codon optimization is a reasonable strategy to improve the yield of α-CGTase for industrial application.
Numerical and functional responses of intestinal helminths in three rajid skates: evidence for competition between parasites?
Authors: RANDHAWA HASEEB S. 
Published: August 2012

SUMMARYHost-parasite interactions generally involve communities of parasites. Within these communities, species will co-exist and/or interact with one another in a manner either benefiting the species involved or to the detriment of one or more of the species. At the level of helminth infracommunities, evidence for intra- and inter-specific competition includes numerical responses, i.e. those regulating helminth intensity of infection, and functional responses, i.e. where the presence of competitors modifies the realised niche of infrapopulations. The objectives of this study are to assess the numerical and functional responses of helminths in infracommunities from 3 rajid skates using general linear models. Despite a lack of numerical responses, functional responses to intra- and inter-specific interactions were observed. A positive correlation between the number of individuals in an infrapopulation and its niche breadth (functional response) was observed for the tapewormsPseudanthobothriumspp. andEcheneibothriumspp., in all their respective hosts, and for the nematodePseudanisakissp. in the little skate. Evidence for inter-specific competition includes niche shifts inPseudanthobothrium purtoni(exlittle skate) andPseudanisakissp. (exthorny skate) in the presence ofPseudanisakissp. and the tapewormGrillotiasp., respectively. These results are consistent with other studies in providing evidence for competition between helminths of skates.
Variation in fecal egg counts in horses managed for conservation purposes: individual egg shedding consistency, age effects and seasonal variation
Authors: WOOD E. L. D. , MATTHEWS J. B. , STEPHENSON S. , SLOTE M. , NUSSEY D. H. 
Published: August 2012

SUMMARYCyathostomins are the most prevalent equine intestinal parasites and resistance has been reported in these nematodes against all 3 licensed anthelmintic classes. Strategies need to be developed that are less dependent upon drugs and more reliant on management-based control. To develop these we need to understand natural transmission patterns better. Here, we analysed longitudinal fecal egg count (FEC) data from 5 pony populations used for conservation purposes. We tested how egg excretion varied amongst populations and individuals, and how this was affected by age and climate. There was evidence for consistency in FECs over time at the individual level; this was generally weak and accounted for <10% of the total variance. Animals <5 years old had higher FECs and there was profound seasonal variation in FECs, with highest levels recorded in spring/summer. Effects of monthly temperature and rainfall explained most, but not all, of the observed seasonal variation and associations between climate measures and FECs were stronger in younger versus adult animals. One population was occasionally treated with anthelmintics and analysis of this population suggested that treatment substantially altered the seasonal dynamics. This paper highlights the variability in strongyle egg excretion amongst individuals and the factors involved in this variation.
Neural response to the observable self in social anxiety disorder
Authors: Pujol J. , Giménez M. , Ortiz H. , Soriano-Mas C. , López-Solà M. , Farré M. , Deus J. , Merlo-Pich E. , Harrison B. J. , Cardoner N. , Navinés R. , Martín-Santos R. 
Published: August 2012

BackgroundDistorted images of the observable self are considered crucial in the development and maintenance of social anxiety. We generated an experimental situation in which participants viewed themselves from an observer's perspective when exposed to scrutiny and evaluation by others.MethodTwenty patients with social anxiety disorder (SAD) and 20 control subjects were assessed using functional magnetic resonance imaging (fMRI) during the public exposure of pre-recorded videos in which they were each shown performing a verbal task. The examiners acted as the audience in the experiment and rated performance. Whole-brain functional maps were computed using Statistical Parametric Mapping.ResultsRobust activation was observed in regions related to self-face recognition, emotional response and general arousal in both study groups. Patients showed significantly greater activation only in the primary visual cortex. By contrast, they showed significant deactivation or smaller activation in dorsal frontoparietal and anterior cingulate cortices relevant to the cognitive control of negative emotion. Task-related anxiety ratings revealed a pattern of negative correlation with activation in this frontoparietal/cingulate network. Importantly, the relationship between social anxiety scores and neural response showed an inverted-U function with positive correlations in the lower score range and negative correlations in the higher range.ConclusionsOur findings suggest that exposure to scrutiny and evaluation in SAD may be associated with changes in cortical systems mediating the cognitive components of anxiety. Disorder severity seems to be relevant in shaping the neural response pattern, which is distinctively characterized by a reduced cortical response in the most severe cases.
Welfare Mom as Warrior Mom: Discourse in the 2003 Single Mothers' Protest in Israel
Authors: HERBST ANAT 
Published: August 2012

AbstractThis study applies critical discourse analysis to the public discourse in Israel regarding the battle of single mothers against extensive welfare cuts. Using the protest of July 2003 as a case study, the article points to parallels between Israel's neo-liberal welfare discourse and that in the US, but also reveals a competing discourse in Israel that incorporated several basic cultural motifs: motherhood, militarism, Zionism and nationalism. While the latter discourse stresses the importance of motherhood and its contribution to society, the former presents single mothers as dependents living off the country's welfare resources. The discourse analysis shows that despite the seeming legitimacy of motherhood in Israel, especially of the Zionist mother who gives birth to soldiers, the negative imagery applied by the neo-liberal ideology to single mothers who receive allowances succeeded in eroding this legitimacy.
Multi-waypoint visual homing in piecewise linear trajectory
Authors: Fu Yu , Hsiang Tien-Ruey , Chung Sheng-Luen 
Published: August 2012

SUMMARYThis paper proposes an image sequence-based navigation method under the teaching-replay framework for robots in piecewise linear routes. Waypoints used by the robot contain either the positions with large heading changes or selected midway positions between junctions. The robot applies local visual homing to move between consecutive waypoints. The arrival at a waypoint is determined by minimizing the average vertical displacements of feature correspondences. The performance of the proposed approach is supported by extensive experiments in hallway and office environments. While the homing speed of robots using other approaches is constrained by the speed in the teaching phase, our robot is not bounded by such limit and can travel much faster without compromising the homing accuracy.