Institution
National Autonomous University of Mexico
Education•Mexico City, Distrito Federal, Mexico•
About: National Autonomous University of Mexico is a education organization based out in Mexico City, Distrito Federal, Mexico. It is known for research contribution in the topics: Population & Galaxy. The organization has 72868 authors who have published 127797 publications receiving 2285543 citations. The organization is also known as: UNAM & Universidad Nacional Autónoma de México.
Topics: Population, Galaxy, Thin film, Species richness, Catalysis
Papers published on a yearly basis
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TL;DR: The coalescence of single-walled nanotubes is studied in situ under electron irradiation at high temperature in a transmission electron microscope, and seems to be restricted to tubes with the same chirality, explaining the low frequency of occurrence of this event.
Abstract: The coalescence of single-walled nanotubes is studied in situ under electron irradiation at high temperature in a transmission electron microscope. The merging process is investigated at the atomic level, using tight-binding molecular dynamics and Monte Carlo simulations. Vacancies induce coalescence via a zipper-like mechanism, imposing a continuous reorganization of atoms on individual tube lattices along adjacent tubes. Other topological defects induce the polymerization of tubes. Coalescence seems to be restricted to tubes with the same chirality, explaining the low frequency of occurrence of this event.
442 citations
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TL;DR: Of the aldehydes tested, only furfural strongly inhibited ethanol production in vitro, and a comparison with published results for other microorganisms indicates that LY01 is equivalent or more resistant than other biocatalysts to the aaldehydes examined in this study.
Abstract: Bioethanol production from lignocellulosic raw-materials requires the hydrolysis of carbohydrate polymers into a fermentable syrup. During the hydrolysis of hemicellulose with dilute acid, a variety of toxic compounds are produced such as soluble aromatic aldehydes from lignin and furfural from pentose destruction. In this study, the authors have investigated the toxicity of representative aldehydes (furfural, 5-hydroxymethlyfurfural, 4-hydroxybenzaldehyde, syringaldehyde, and vanillin) as inhibitors of growth and ethanol production by ethanologenic derivatives of Escherichia coli B (strains K011 and LY01). Aromatic aldyhydes were at least twice as toxic as furfural of 5-hydroxymethylfurfural on a weight basis. The toxicities of all aldehydes (and ethanol) except furfural were additive when tested in binary combinations. In all cases, combinations with furfural were unexpectedly toxic. Although the potency of these aldehydes was directly related to hydrophobicity indicating a hydrophobic site of action, none caused sufficient membrane damage to allow the leakage of intracellular magnesium even when present at sixfold the concentrations required for growth inhibition. Of the aldehydes tested, only furfural strongly inhibited ethanol production in vitro. A comparison with published results for other microorganisms indicates that LY01 is equivalent or more resistant than other biocatalysts to the aldehydes examined in this study.
442 citations
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TL;DR: It is concluded that various tools and indicators are available for developing the ecological engineering of the rhizobial symbiosis, in particular for its beneficial contribution to the bio-geochemical cycle of N, and also P and C.
Abstract: As a major contributor to the reduced nitrogen pool in the biosphere, symbiotic nitrogen fixation by legumes plays a critical role in a sustainable production system. However this legume contribution varies with the physico-chemical and biological conditions of the nodulated-root rhizosphere. In order to assess the abiotic and biotic constrains that might limit this symbiosis at the agroecosystem level, a nodular diagnosis is proposed with common bean as a model grain-legume, and a major source of plant proteins for world human nutrition. The engineering of the legume symbiosis is addressed by participatory assessment of bean recombinant inbred lines contrasting for their efficiency in use of phosphorous for symbiotic nitrogen fixation. With this methodology, in field-sites chosen with farmers of an area of cereal-cropping in the Mediterranean basin, a large spatial and temporal variation in the legume nodulation was found. Soil P availability was a major limiting factor of the rhizobial symbiosis. In order to relate the field measurements with progress in functional genomics of the symbiosis, in situ RT-PCR on nodule sections has been implemented showing that the phytase gene is expressed in the cortex with significantly higher number of transcripts in P-efficient RILs. It is concluded that various tools and indicators are available for developing the ecological engineering of the rhizobial symbiosis, in particular for its beneficial contribution to the bio-geochemical cycle of N, and also P and C.
440 citations
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TL;DR: In this paper, a discussion of the complementary nature of MO theory and QTAIM is presented, together with the means of bridging the two approaches in a discussion about the bonding in the carbonyl complexes of Cr, Fe and Ni and the metallocene complexes of Fe, Al+ and Ge.
439 citations
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Max Planck Society1, Heidelberg University2, Space Telescope Science Institute3, University of Barcelona4, INAF5, California Institute of Technology6, University of Arizona7, University of California, San Diego8, National Autonomous University of Mexico9, Harvard University10, University of California, Berkeley11, ETH Zurich12, Ehime University13
TL;DR: In this article, the authors analyzed 140 XMM-Newton-selected AGN host galaxies and a matched control sample of 1264 inactive galaxies over z ~ 0.3 − 1.0 and M∗ < 10^(11.7) M ∆ with high-resolution Hubble Space Telescope/Advanced Camera for Surveys imaging from the COSMOS field.
Abstract: What is the relevance of major mergers and interactions as triggering mechanisms for active galactic nuclei (AGNs)
activity? To answer this long-standing question, we analyze 140 XMM-Newton-selected AGN host galaxies and
a matched control sample of 1264 inactive galaxies over z ~ 0.3–1.0 and M_∗ < 10^(11.7) M_⊙ with high-resolution
Hubble Space Telescope/Advanced Camera for Surveys imaging from the COSMOS field. The visual analysis of
their morphologies by 10 independent human classifiers yields a measure of the fraction of distorted morphologies
in the AGN and control samples, i.e., quantifying the signature of recent mergers which might potentially be
responsible for fueling/triggering the AGN. We find that (1) the vast majority (>85%) of the AGN host galaxies
do not show strong distortions and (2) there is no significant difference in the distortion fractions between active
and inactive galaxies. Our findings provide the best direct evidence that, since z ~ 1, the bulk of black hole (BH)
accretion has not been triggered by major galaxy mergers, therefore arguing that the alternative mechanisms, i.e.,
internal secular processes and minor interactions, are the leading triggers for the episodes of major BH growth.We
also exclude an alternative interpretation of our results: a substantial time lag between merging and the observability
of the AGN phase could wash out the most significant merging signatures, explaining the lack of enhancement
of strong distortions on the AGN hosts. We show that this alternative scenario is unlikely due to (1) recent major
mergers being ruled out for the majority of sources due to the high fraction of disk-hosted AGNs, (2) the lack of
a significant X-ray signal in merging inactive galaxies as a signature of a potential buried AGN, and (3) the low
levels of soft X-ray obscuration for AGNs hosted by interacting galaxies, in contrast to model predictions.
439 citations
Authors
Showing all 73617 results
Name | H-index | Papers | Citations |
---|---|---|---|
Richard Peto | 183 | 683 | 231434 |
Anton M. Koekemoer | 168 | 1127 | 106796 |
Rory Collins | 162 | 489 | 193407 |
Timothy C. Beers | 156 | 934 | 102581 |
Vivek Sharma | 150 | 3030 | 136228 |
Kjell Fuxe | 142 | 1479 | 89846 |
Prashant V. Kamat | 140 | 725 | 79259 |
Carmen García | 139 | 1503 | 96925 |
Harold A. Mooney | 135 | 450 | 100404 |
Efe Yazgan | 128 | 986 | 79041 |
Roberto Maiolino | 127 | 816 | 61724 |
Peter Nugent | 127 | 754 | 92988 |
William R. Miller | 125 | 601 | 72570 |
Nicholas A. Kotov | 123 | 574 | 55210 |
John C. Wingfield | 122 | 509 | 52291 |