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A brief history of the Rheic Ocean 被引量:4
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作者 R.Damian Nance Gabriel Gutirrez-Alonso +5 位作者 J.Duncan Keppie Ulf Linnemann J.Brendan Murphy Cecilio Quesada Rob A.Strachan Nigel H.Woodcock 《Geoscience Frontiers》 SCIE CAS 2012年第2期125-135,共11页
The Rheic Ocean was one of the most important oceans of the Paleozoic Era. It lay between Laurentia and Gondwana from the Early Ordovician and closed to produce the vast Ouachita- Alleghanian-Variscan orogen during th... The Rheic Ocean was one of the most important oceans of the Paleozoic Era. It lay between Laurentia and Gondwana from the Early Ordovician and closed to produce the vast Ouachita- Alleghanian-Variscan orogen during the assembly of Pangea. Rifting began in the Cambrian as a continua- tion of Neoproterozoic orogenic activity and the ocean opened in the Early Ordovician with the separation of several Neoproterozoic arc terranes from the continental margin of northern Gondwana along the line of a former suture. The rapid rate of ocean opening suggests it was driven by slab pull in the outboard Iapetus Ocean. The ocean reached its greatest width with the closure of Iapetus and the accretion of the peri- Gondwanan arc terranes to Laurentia in the Silurian. Ocean closure began in the Devonian and continued through the Mississippian as Gondwana sutured to Laurussia to form Pangea. The ocean consequently plays a dominant role in the Appalachian-Ouachita orogeny of North America, in the basement geology of southern Europe, and in the Paleozoic sedimentary, structural and tectonothermal record from Middle America to the Middle East. Its closure brought the Paleozoic Era to an end. 展开更多
关键词 Rheic Ocean Variscan-Alleghanian-Ouachita orogen PANGEA North America EUROPE
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Glutamate dehydrogenase and Na^+-K^+ ATPase expression and growth response of Litopenaeus vannamei to different salinities and dietary protein levels 被引量:2
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作者 李二超 Leticia ARENA +5 位作者 Gabriel LIZAMA Gabriela GAXIOLA Gerard CUZON Carlos ROSAS 陈立侨 Alain VAN WORMHOUDT 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2011年第2期343-349,共7页
Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture.The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp(L.vanname... Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture.The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp(L.vannamei) were investigated.This involved an examination of growth performance,glutamate dehydrogenase(GDH) and Na+-K+ ATPase mRNA expression,,and GDH activity in muscles and gills.Three experimental diets were formulated,containing 25%,40%,and 50% dietary protein,and fed to the shrimp at a salinity of 25.After 20 days,no significant difference was observed in weight gain,though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels.Subsequently,shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5,respectively,and sampled at weeks 1 and 2.Shrimp fed with 40% protein at 25 in salinity(optimal conditions) were used as a control.Regardless of the salinities,shrimp fed with 50% dietary protein had significantly higher growth performance than other diets;no significant differences were found in comparison with the control.Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks.Ambient salinity change also stimulated the hepatosomatic index,which increased in the first week and then recovered to a relatively normal level,as in the control,after 2 weeks.These findings indicate that in white shrimp,the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism.Increased dietary protein level could improve the osmoregulation capacity of L.vannamei with more energy resources allocated to GDH activity and expression. 展开更多
关键词 Litopenaeus vannamei gene expression glutamate dehydrogenase Na^+-K^+ ATPase PROTEIN SALINITY
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Synthesis of Pt and Pt-Fe nanoparticles supported on MWCNTs used as electrocatalysts in the methanol oxidation reaction 被引量:1
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作者 J.R.Rodriguez R.M.Félix +4 位作者 E.A.Reynoso Y.Gochi-Ponce Y.Verde Gómez S.Fuentes Moyado G.Alonso-Núez 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2014年第4期483-490,共8页
This work reports a feasible synthesis of highly-dispersed Pt and Pt-Fe nanoparticles supported on multiwall carbon nanotubes (MWCNTs) without Fe and multiwall carbon nanotubes with iron (MWCNTs-Fe) which applied ... This work reports a feasible synthesis of highly-dispersed Pt and Pt-Fe nanoparticles supported on multiwall carbon nanotubes (MWCNTs) without Fe and multiwall carbon nanotubes with iron (MWCNTs-Fe) which applied as electrocatalysts for methanol electrooxidation. A Pt coordination complex salt was synthesized in an aqueous solution and it was used as precursor to prepare Pt/MWCNTs, Pt/MWCNTs-Fe, and Pt-Fe/MWCNTs using FeC12.4H20 as iron source which were named S 1, S2 and S3, respectively. The coordination complex of platinum (TOA)2PtC16 was obtained by the chemical reaction between (NH4)2PtC16 with tetraoctylammonium bromide (TOAB) and it was characterized by FT-IR and TGA. The materials were characterized by Raman spectroscopy, SEM, EDS, XRD, TEM and TGA. The electrocatalytic activity of Pt-based supported on MWCNTs in the methanol oxidation was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Pt-Fe/MWCNTs electrocatalysts showed the highest electrocatalytic activity and stability among the tested electrocatalysts due to that the addition of "Fe" promotes the OH species adsorption on the electrocatalyst surface at low potentials, thus, enhancing the activity toward the methanol oxidation reaction (MOR). 展开更多
关键词 coordination complex salt MWCNTS nanoparticles CATALYSTS ELECTROOXIDATION
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Transcriptional Regulation and Signaling in Phosphorus Starvation: What About Legumes? 被引量:4
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作者 Oswaldo Valds-López Georgina Hernndez 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2008年第10期1213-1222,共10页
The availability of soil phosphorus (P), an essential element, is one of the most important requirements for plant growth and crop production. The morphological and physiological adaptations evolved by plants to cop... The availability of soil phosphorus (P), an essential element, is one of the most important requirements for plant growth and crop production. The morphological and physiological adaptations evolved by plants to cope with P starvation have been well characterized. Several P deficiency plant responses are regulated at the transcriptional level. Microarray analysis has generated valuable information on global gene expression in Arabidopsis thaliana grown under P-stress. Despite the identification of P responsive genes, little is known about the regulation of gene expression changes. Four transcription factors, PHRI, WRKY75, ZAT6 and BHLH32, involved in P starvation signaling have been characterized in Arabidopsis, and signaling pathways are deciphered. This review analyzes the current knowledge of transcriptional regulation of P starvation responses in Arabidopsis vis-a-vis legumes such as lupine, common bean and Medicago truncatula. The knowledge on regulatory and signaling mechanisms involved in P acquisition and use in legumes will be useful for improvement of these crops, which account for a large proportion of the world's crop production, providing good nutritional quality feed and food. 展开更多
关键词 legumes phosphorus starvation responses P starvation signaling pathways transcriptional regulation transcription factors.
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On Second Order Degree of Graphs
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作者 Gabriela ARAUJO-PARDO Camino BALBUENA +1 位作者 Mika OLSEN Pilar VALENCIA 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2012年第1期171-182,共12页
Given a vertex v of a graph G the second order degree of v denoted as d2(v) is defined as the number of vertices at distance 2 from v. In this paper we address the following question: What axe the sufficient condit... Given a vertex v of a graph G the second order degree of v denoted as d2(v) is defined as the number of vertices at distance 2 from v. In this paper we address the following question: What axe the sufficient conditions for a graph to have a vertex v such that d2(v) ≥ d(v), where d(v) denotes the degree of v? Among other results, every graph of minimum degree exactly 2, except four graphs, is shown to have a vertex of second order degree as large as its own degree. Moreover, every K4^--free graph or every maximal planar graph is shown to have a vertex v such that d2(v) ≥ d(v). Other sufficient conditions on graphs for guaranteeing this property axe also proved. 展开更多
关键词 Second order degree K4^-free graph planar graphs
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