bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on photoemission mechanism for negative electron affinity GaN vacuum electron source
Authors: Qiao Jianliang , Chang Benkang , Qian Yunsheng , Wang Xiaohui , Li Biao , Fu Xiaoqian 
Published: September 2011

AbstractThe whole process including photoelectron excitation, transportation from bulk to surface and escape to vacuum by traversing surface barrier was analyzed in detail. Photoelectron excitation relates to the band structure of photocathode material and the absorption coefficient of the material. In the bulk of GaN photocathode, the photoelectrons mainly are transited into Γ valley first, when the energy is great enough, the photoelectrons can scatter into higher M‐L valley or A valley from Γ valley. The electrons excitated in conduction band will move from bulk to surface by diffusing or drifting. The diffuse length for GaN photocathode is about 3μm by calculating. After the thermal electrons of Γ valley move into surface band bend area, they will drift to the surface because of the electric field of band bend area. The transmission coefficient relates to the incident electron energy, the height and width of the surface potential. The quantum yield formulas of NEA GaN photocathode were gotten by solving the diffuse equation of non‐equilibrium carriers. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of outgassing on the field emission property of tetrapod ZnO
Authors: Cui Yunkang , Zhang Xiaobing , Lei Wei , Wang Jinchan , Di Yunsong , Yang Xiaxi , Chen Jing 
Published: September 2011

AbstractTo study the mechanism of current degradation of a cold cathode, the outgassing measurement of a field emission diode with tetrapod zinc oxide (ZnO) cathode has been taken with a quadrupole mass spectrometer (QMS) in an ultra‐high vacuum (UHV) system. It was found that the H2, CO2, CO, and CH4 were outgassed from the diode during the working process. The partial pressure of outgassing increases with the increased emission current density. The field emission properties of the cold cathode, such as turn‐on field, threshold field and the emission current density, were largely related to the pressure of the outgases. From the outgassing experimental results, the relation between the emission current degradation and the outgassing of field emission devices has been found. Due to the outgassing, the work function of ZnO cold cathode increases, while the field enhancement factor decreases. Therefore, the outgassing plays very important role in the current degradation for the field emission devices (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ARE TWO SYSTEMIC FISH ASSEMBLAGE SAMPLING PROGRAMMES ON THE UPPER MISSISSIPPI RIVER TELLING US THE SAME THING?
Authors: Dukerschein J. T. , Bartels A. D. , Ickes B. S. , Pearson M. S. 
Published: September 2011

ABSTRACTWe applied an Index of Biotic Integrity (IBI) used on Wisconsin/Minnesota waters of the upper Mississippi River (UMR) to compare data from two systemic sampling programmes. Ability to use data from multiple sampling programmes could extend spatial and temporal coverage of river assessment and monitoring efforts. We normalized for effort and tested fish community data collected by the Environmental Monitoring and Assessment Program‐Great Rivers Ecosystems (EMAP‐GRE) 2004–2006 and the Long Term Resource Monitoring Program (LTRMP) 1993–2006. Each programme used daytime electrofishing along main channel borders but with some methodological and design differences. EMAP‐GRE, designed for baseline and, eventually, compliance monitoring, used a probabilistic, continuous design. LTRMP, designed primarily for baseline and trend monitoring, used a stratified random design in five discrete study reaches. Analysis of similarity indicated no significant difference between EMAP‐GRE and LTRMP IBI scores (n = 238; Global R = −0.052; significance level = 0.972). Both datasets distinguished clear differences only between ‘Fair’ and ‘Poor’ condition categories, potentially supporting a ‘pass–fail’ assessment strategy. Thirteen years of LTRMP data demonstrated stable IBI scores through time in four of five reaches sampled. LTRMP and EMAP‐GRE IBI scores correlated along the UMR's upstream to downstream gradient (df [3, 25]; F = 1.61; p = 0.22). A decline in IBI scores from upstream to downstream was consistent with UMR fish community studies and a previous, empirically modelled human disturbance gradient. Comparability between EMAP‐GRE (best upstream to downstream coverage) and LTRMP data (best coverage over time and across the floodplain) supports a next step of developing and testing a systemic, multi‐metric fish index on the UMR that both approaches could inform. Copyright © 2011 John Wiley & Sons, Ltd.
A Novel Role for an RNA Polymerase III Subunit POLR3G in Regulating Pluripotency in Human Embryonic Stem Cells
Authors: Wong Raymond Ching-Bong , Pollan Sara , Fong Helen , Ibrahim Abel , Smith Ellen L. , Ho Mirabelle , Laslett Andrew L. , Donovan Peter J. 
Published: September 2011

Abstract
The pluripotency of human embryonic stem cells (hESC) could have great potential for the development of cell replacement therapies. Previous studies have converged on the finding that OCT4, SOX2, and NANOG serve as key regulators in the maintenance of hESC. However, other signals that regulate hESC maintenance remain poorly studied. Here we describe a novel role of an RNA polymerase III (Pol III) subunit, POLR3G, in the maintenance of pluripotency in hESC. We demonstrate the presence of POLR3G in undifferentiated hESC, human induced pluripotent stem cells (hiPSC), and early mouse blastocysts. Downregulation of POLR3G is observed on differentiation of hESC and hiPSC, suggesting that POLR3G can be used as a molecular marker to readily identify undifferentiated pluripotent stem cells from their differentiated derivatives. Using an inducible shRNA lentiviral system, we found evidence that decreased levels of POLR3G result in loss of pluripotency and promote differentiation of hESC to all three germ layers but have no effect on cell apoptosis. On the other hand, overexpression of POLR3G has no effect on pluripotency and apoptosis in undifferentiated hESC. Interestingly, hESC expressing elevated levels of POLR3G are more resistant to differentiation. Furthermore, our experimental results show that POLR3G is a downstream target of OCT4 and NANOG, and our pharmacological study indicated that POLR3G expression can be readily regulated by the Erk1/2 signaling pathway. This study is the first to show an important role of POLR3G in the maintenance of hESC, suggesting a potential role of Pol III transcription in regulating hESC pluripotency.
Effects on Proliferation and Differentiation of Multipotent Bone Marrow Stromal Cells Engineered to Express Growth Factors for Combined Cell and Gene Therapy
Authors: Fierro Fernando A. , Kalomoiris Stefanos , Sondergaard Claus S. , Nolta Jan A. 
Published: September 2011

AbstractA key mechanism for mesenchymal stem cells/bone marrow stromal cells (MSCs) to promote tissue repair is by secretion of soluble growth factors (GFs). Therefore, clinical application could be optimized by a combination of cell and gene therapies, where MSCs are genetically modified to express higher levels of a specific factor. However, it remains unknown how this overexpression may alter the fate of the MSCs. Here, we show effects of overexpressing the growth factors, such as basic fibroblast growth factor (bFGF), platelet derived growth factor B (PDGF-BB), transforming growth factor β1 (TGF-β1), and vascular endothelial growth factor (VEGF), in human bone marrow-derived MSCs. Ectopic expression of bFGF or PDGF-B lead to highly proliferating MSCs and lead to a robust increase in osteogenesis. In contrast, adipogenesis was strongly inhibited in MSCs overexpressing PDGF-B and only mildly affected in MSCs overexpressing bFGF. Overexpression of TGF-β1 blocked both osteogenic and adipogenic differentiation while inducing the formation of stress fibers and increasing the expression of the smooth muscle marker calponin-1 and the chondrogenic marker collagen type II. In contrast, MSCs overexpressing VEGF did not vary from control MSCs in any parameters, likely due to the lack of VEGF receptor expression on MSCs. MSCs engineered to overexpress VEGF strongly induced the migration of endothelial cells and enhanced blood flow restoration in a xenograft model of hind limb ischemia. These data support the rationale for genetically modifying MSCs to enhance their therapeutically relevant trophic signals, when safety and efficacy can be demonstrated, and when it can be shown that there are no unwanted effects on their proliferation and differentiation.
Hydroarylation of alkynes catalyzed by nickel
Authors: Nakao Yoshiaki 
Published: September 2011

AbstractNickel catalysts derived from bis(1,5‐cyclooctadiene)nickel [Ni(cod)2] and trialkylphosphines effect hydroarylation of alkynes through functionalization of C–H bonds of arenes including benzo‐fused five‐membered heteroarenes, pyridine‐N‐oxides, pyridines, 2‐pyridones, and perfluoroarenes. The reactions proceed with excellent stereo‐ and regioselectivity to give disubstituted arylethenes in good yields. Use of Lewis acid (LA) co‐catalysts is crucial for success in reactions of imidazoles, pyridines, and 2‐pyridones; it is possible that coordination of the LA to the nitrogen or oxygen functionalities of such substrates increases the reactivity of their C–H bonds towards nickel(0) species. DOI 10.1002/tcr.201100023
Facilitating change in undergraduate STEM instructional practices: An analytic review of the literature
Authors: Henderson Charles , Beach Andrea , Finkelstein Noah 
Published: September 2011

AbstractThis article reviews current scholarship about how to promote change in instructional practices used in undergraduate science, technology, engineering, and mathematics (STEM) courses. The review is based on 191 conceptual and empirical journal articles published between 1995 and 2008. Four broad categories of change strategies were developed to capture core differences within this body of literature: disseminating curriculum and pedagogy, developing reflective teachers, enacting policy, and developing shared vision. STEM education researchers largely write about change in terms of disseminating curriculum and pedagogy. Faculty development researchers largely write about change in terms of developing reflective teachers. Higher education researchers largely write about change in terms of enacting policy. New work often does not build on prior empirical or theoretical work. Although most articles claim success of the change strategy studied, evidence presented to support these claims is typically not strong. For example, only 21% of articles that studied implementation of a change strategy were categorized as presenting strong evidence to support claims of success or failure of the strategy. These analyses suggest that the state of change strategies and the study of change strategies are weak, and that research communities that study and enact change are largely isolated from one‐another. In spite of the weak state of the literature, some conclusions related to the design of change strategies can be drawn from this review. Two commonly used change strategies are clearly not effective: developing and testing “best practice” curricular materials and then making these materials available to other faculty and “top‐down” policy‐making meant to influence instructional practices. Effective change strategies: are aligned with or seek to change the beliefs of the individuals involved; involve long‐term interventions, lasting at least one semester; require understanding a college or university as a complex system and designing a strategy that is compatible with this system. © 2011 Wiley Periodicals, Inc. J Res Sci Teach 48: 952–984, 2011
Normal morphogenesis of epithelial tissues and progression of epithelial tumors
Authors: Wang Chun‐Chao , Jamal Leen , Janes Kevin A. 
Published: September 2011

AbstractEpithelial cells organize into various tissue architectures that largely maintain their structure throughout the life of an organism. For decades, the morphogenesis of epithelial tissues has fascinated scientists at the interface of cell, developmental, and molecular biology. Systems biology offers ways to combine knowledge from these disciplines by building integrative models that are quantitative and predictive. Can such models be useful for gaining a deeper understanding of epithelial morphogenesis? Here, we take inventory of some recurring themes in epithelial morphogenesis that systems approaches could strive to capture. Predictive understanding of morphogenesis at the systems level would prove especially valuable for diseases such as cancer, where epithelial tissue architecture is profoundly disrupted. WIREs Syst Biol Med 2012, 4:51–78. doi: 10.1002/wsbm.159This article is categorized under:

Physiology > Mammalian Physiology in Health and Disease
Tolerance to thermal and reductive stress in Saccharomyces cerevisiae is amenable to regulation by phosphorylation–dephosphorylation of ubiquitin conjugating enzyme 1 (Ubc1) S97 and S115
Authors: Meena Ramesh C. , Thakur Suresh , Nath Surendra , Chakrabarti Amitabha 
Published: September 2011

AbstractUbiquitin conjugating enzyme 1 (Ubc1) is a member of the E2 family of enzymes that conjugates ubiquitin to damaged proteins destined for degradation by the ubiquitin proteasomal system. It is necessary for stress tolerance and is essential for cell survival in Saccharomyces cerevisiae. Ubc1 has five serine residues that are potential substrates for phosphorylation by kinases. However, no data are available to indicate that Ubc1 function or stress tolerance in S. cerevisiae is regulated by serine phosphorylation of Ubc1. We demonstrate that Ubc1 is phosphorylated in serine residue(s). Furthermore, expression of Ubc1 mutants that are ‘constitutively phosphorylated’ or ‘dephosphorylated’ in mitogen‐activated protein (MAP) kinase serine residues (S97 and S115) affected tolerance to thermal and reductive stress in S. cerevisiae. Specifically, expression of Ubc1S97A and S115D increased thermo‐tolerance in both BY4741 and TetO7‐UBC1ura3Δ cells. Serine phosphorylation of Ubc1 was decreased in BY4741 cells following exposure at 40 °C. Tolerance to reductive stress in the same strains correlated with the expression of Ubc1S97A. Ubc1 phosphorylation did not show significant alteration under similar conditions. Both hog1Δ and slt2Δ cells expressing Ubc1S115D and Ubc1S115A were rendered tolerant to thermal and reductive stress respectively. Ubc1 phosphorylation was higher in BY4741 cells compared to hog1Δ cells at 30 °C and was significantly reduced in BY4741 cells upon exposure at 40 °C. Taken together, the cell survival assays and Ubc1 phosphorylation status in strains and under conditions as described above suggest that tolerance to thermal and reductive stress in S. cerevisiae may be regulated by MAP kinase‐mediated phosphorylation of Ubc1S97 and S115. Copyright © 2011 John Wiley & Sons, Ltd.
Glucose signalling pathway controls the programmed ribosomal frameshift efficiency in retroviral‐like element Ty3 in Saccharomyces cerevisiae
Authors: Türkel Sezai , Kaplan Güliz , Farabaugh Philip J. 
Published: September 2011

AbstractTy3 elements of S. cerevisiae contain two overlapping coding regions, GAG3 and POL3, which are functional homologues of retroviral gag and pol genes, respectively. Pol3 is translated as a Gag3‐Pol3 fusion protein dependent on a +1 programmed frameshift at a site with the overlap between the two genes. We show that the Ty3 frameshift frequency varies up to 10‐fold in S. cerevisiae cells depending on carbon source. Frameshift efficiency is significantly lower in cells growing on glucose as carbon source than in cells growing on poor alternative carbon sources (glycerol/lactate or galactose). Our results indicate that Ty3 programmed ribosomal frameshift efficiency in response to glucose signalling requires two protein kinases: Snf1p and cAMP‐dependent protein kinase A (PKA). Increased frameshifting on alternative carbon sources also appears to require cytoplasmic localization of Snf1p, mediated by the Sip2p protein. In addition to the two required protein kinases, our results implicate that Stm1p, a ribosome‐associated protein involved in nutrient sensing, is essential for the carbon source‐dependent regulation of Ty3 frameshifting. These data indicate that Ty3 programmed ribosomal frameshift is not a constitutive process but that it is regulated in response to the glucose‐signalling pathway. Copyright © 2011 John Wiley & Sons, Ltd.
Interleukin‐15 Affects Differentiation and Apoptosis in Adipocytes: Implications in Obesity
Authors: Fuster Gemma , Almendro Vanessa , Fontes‐Oliveira Cibely Cristine , Toledo Míriam , Costelli Paola , Busquets Sílvia , López‐Soriano Francisco J. , Argilés Josep M. 
Published: September 2011

AbstractInterleukin‐15 (IL‐15) is an anabolic factor for skeletal muscle and several reports have described its important role as a regulator of energy homeostasis. In this study, we analyzed the effects of IL‐15 on adipocyte differentiation using the 3T3‐L1 preadipose cell line. The data show that IL‐15 tends to reduce the rate of adipocyte proliferation, induces apoptosis, and partially stops differentiation. The signaling molecules behind these actions of the cytokine on adipose cells are: p42/p44 MAPK (which seem to be associated with the reduced rate of proliferation induced by the cytokine), STAT5 (which is related to the actions of IL‐15 on differentiation), and SAPK/JNK (which are related to the increased apoptosis induced by IL‐15). In conclusion, using the 3T3‐L1 adipocyte cell line, the results presented here show that IL‐15 exerts important effects on differentiation, proliferation and apoptosis. Altogether, the results presented here reinforce the idea that IL‐15 is an important mediator that regulates adipose size and, therefore, the role of the cytokine in affecting body weight and obesity deserves additional studies.
Application of a Novel, Heated, Nine‐Reflection ATR Crystal and a Portable FTIR Spectrometer to the Rapid Determination of Total Trans Fat
Authors: Mossoba Magdi M. , Kramer John K. G. , Azizian Hormoz , Kraft Jana , Delmonte Pierluigi , Kia Ali‐Reza Fardin , Bueso Francisco J. , Rader Jeanne I. , Lee Jung K. 
Published: September 2011

AbstractSince trans fat labeling requirements became mandatory in the US and many other countries, there has been a need for rapid and accurate analytical methodologies that can facilitate compliance with the various regulations. The determination of total trans fatty acids by mid‐infrared (IR) spectroscopy is a widely used procedure that was standardized and validated as AOCS Official Method Cd 14e‐09 (negative second derivative infrared spectroscopic method for the rapid (5 min) determination of total isolated trans fat) in 2009. The C–H out‐of‐plane deformation mid‐IR band observed at 966 cm−1 is uniquely characteristic of isolated (non‐conjugated) double bonds with trans configuration. AOCS Official Method Cd 14e‐09, the most recent attenuated total reflection‐Fourier transform IR (ATR‐FTIR) official method, entails the measurement of the height of the negative second derivative of the trans absorption band. In the present study, the performance of a novel, portable FTIR system equipped with a heated 9‐bounce diamond ATR crystal was evaluated and compared to that of a conventional benchtop single‐bounce ATR‐FTIR spectrometer. The introduction of the 9‐bounce diamond ATR crystal resulted in the lowering of the limit of quantification of trans fat, as a percentage of the total fat, from approximately 2 to 0.34%. The data collected from accurately weighed gravimetric standards and 28 unknown test samples ranging in trans fat content from about 0.5 to 54%, as a percentage of the total fat, indicated that this IR official method and the use of the new 9‐bounce portable ATR‐FTIR instrumentation could lead to a five‐fold enhancement in sensitivity relative to single‐bounce systems. Implementing these changes would facilitate regulatory compliance and verification of fat and oil samples for trans fat content in the US and other countries, since all of the published regulations (e.g., “0 g trans fat per serving”) have levels of trans fat, as percentage of total fat, that exceed 0.34%.
Successful development of microsatellite markers in a challenging species: the horizontal borerAustroplatypus incompertus(Coleoptera: Curculionidae)
Authors: Smith S. , Joss T. , Stow A. 
Published: September 2011

AbstractThe analysis of microsatellite loci has allowed significant advances in evolutionary biology and pest management. However, until very recently, the potential benefits have been compromised by the high costs of developing these neutral markers. High-throughput sequencing provides a solution to this problem. We describe the development of 13 microsatellite markers for the eusocial ambrosia beetle,Austroplatypus incompertus, a significant pest of forests in southeast Australia. The frequency of microsatellite repeats in the genome ofA. incompertuswas determined to be low, and previous attempts at microsatellite isolation using a traditional genomic library were problematic. Here, we utilised two protocols, microsatellite-enriched genomic library construction and high-throughput 454 sequencing and characterised 13 loci which were polymorphic among 32 individuals. Numbers of alleles per locus ranged from 2 to 17, and observed and expected heterozygosities from 0.344 to 0.767 and from 0.507 to 0.860, respectively. These microsatellites have the resolution required to analyse fine-scale colony and population genetic structure. Our work demonstrates the utility of next-generation 454 sequencing as a method for rapid and cost-effective acquisition of microsatellites where other techniques have failed, or for taxa where marker development has historically been both complicated and expensive.
Development and use of EST-SSR markers for assessing genetic diversity in the brown planthopper (Nilaparvata lugensStål)
Authors: Jing S. , Liu B. , Peng L. , Peng X. , Zhu L. , Fu Q. , He G. 
Published: September 2011

AbstractTo assess genetic diversity in populations of the brown planthopper (Nilaparvata lugensStål) (Homoptera: Delphacidae), we have developed and applied microsatellite, or simple sequence repeat (SSR), markers from expressed sequence tags (ESTs). We found that the brown planthopper clusters of ESTs were rich in SSRs with unique frequencies and distributions of SSR motifs. Three hundred and fifty-one EST-SSR markers were developed and yielded clear bands from samples of four brown planthopper populations. High cross-species transferability of these markers was detected in the closely related planthopperN. muiri. The newly developed EST-SSR markers provided sufficient resolution to distinguish within and among biotypes. Analyses based on SSR data revealed host resistance-based genetic differentiation among different brown planthopper populations; the genetic diversity of populations feeding on susceptible rice varieties was lower than that of populations feeding on resistant rice varieties. This is the first large-scale development of brown planthopper SSR markers, which will be useful for future molecular genetics and genomics studies of this serious agricultural pest.
A Bayesian approach for correcting for partial plating in fluctuation experiments
Authors: ZHENG QI 
Published: September 2011

SummaryThe fluctuation experiment is the preferred method for estimating microbial mutation rates. A difficult task facing the data analyst is to infer the mean number of mutations from the number of mutant cells that only indirectly reflects the number of mutations. Partial plating, commonly practised in the laboratory, renders this task even more challenging by allowing only a portion of the mutant cells to be counted. In this paper, we propose a Bayesian approach to correcting for partial plating in the analysis of fluctuation experiments.