1,032 research outputs found
Effects of international trade of food and feed and human diet shifts on food security and environmental safety: integrating scales
4 p.*International trade of food and feed (expressed as protein content) has increased eightfold during the last 50 years. Nowadays a small number of countries are feeding the rest of the world. Population growth but also a change to higher animal-protein diets are important drivers of the observed changes. *The increasing disconnection between crops (land) and livestock is producing a decrease in nutrient use efficiency at the global scale and a rise in pollution issues. *In Spain, a transition from the so-called Mediterranean diet to a diet with very high share of animal protein that is similar to North American and North European diets, that are much unhealthier, is the main driver of a dramatic increase in the nitrogen (N) pollution. The huge production of animal products is fuelled by feed imports that today equal national crop production. *Despite Spain produces commodities for export, the net balance of N2O emissions of the agricultural system in 2009 indicated that the emissions associated to the production of imported food and feed are higher. A large part of the net N2O emissions associated with imported agricultural commodities is coming from non-Annex B countries and therefore substantial emission leakage is occurring. *Making the most sustainable use of crop by-products is not necessarily incentivised by policies on agricultural commodity markets, which may have a remarkable and undesired effect on the carbon footprint of livestock products (e.g. milk). *Localization of vegetal and animal production, the reduction of food waste, as well as control of diet, are key factors for world food security and environmental safety. *Less intensive farming could be viable if nutrient losses along the food chain are sharply decreased and human diet shifts are also occurring. Linking appropriately policies that deal with food, agriculture, waste, health, climate change, biodiversity and energy are needed to effectively reduce greenhouse gas (GHG) emissions globally
A vast range of opportunities for feeding the world in 2050: trade-off between diet, N contamination and international trade
International audienceThrough a detailed analysis of the FAO database, we have constructed a generalized representation of the nitrogen transfers characterizing the current agro-food system (GRAFS) of 12 macro-regions of the world in terms of functional relationships between crop farming, livestock breeding and human nutrition. Based on this model, and maintaining the current cropland areas and the performance of cropping and livestock systems in each region, we have assessed the possibilities of meeting the protein requirements of the estimated world population in 2050, according to various combinations of three critical drivers namely human diet (total amount of protein consumed and share of animal protein in this total), regional livestock production and crop fertilization intensity, in each region. The results show that feeding the projected 2050 world population would generally imply higher levels of inter-regional trade and of environmental nitrogen contamination than the current levels, but that the scenarios with less recourse to inter-regional trade generally produce less N losses to the environment. If an equitable human diet (in terms of protein consumption) is to be established globally (the same in all regions of the world), the fraction of animal protein should not exceed 40% of a total ingestion of 4 kgN capita(-1) yr(-1), or 25% of a total consumption of 5 kgN capita(-1) yr(-1). Our results show that slightly improving the agronomical performance in the most deficient regions (namely Maghreb, the Middle East, sub-Saharan Africa, and India) would make it possible not only to meet the global protein requirements with much less international trade (hence more food sovereignty), but also to reduce N environmental contamination the most efficiently
Hydrazones as Singular Reagents in Asymmetric Organocatalysis
This Minireview summarizes strategies and developments regarding the use of hydrazones as reagents in asymmetric organocatalysis, their distinct roles in nucleophile–electrophile, cycloaddition, and cyclization reactions. The key structural elements governing the reactivity of these reagents in a preferred pathway will be discussed, as well as their different interactions with organocatalysts, leading to diverse activation modes. Along these studies, the synthetic equivalence of N-monoalkyl, N,N-dialkyl, and N-acyl hydrazones with several synthons is also highlighted. Emphasis is also put on the mechanistic studies performed to understand the observed reactivities. Finally, the functional group transformations performed from the available products has also been analyzed, highlighting the synthetic value of these methodologies, which served to access numerous families of valuable multifunctional compounds and nitrogen-containing heterocycles.Ministerio de Economía y Competitividad CTQ2013-48164-C2-1-P, CTQ201348164-C2-2-PEuropean FEDER fundsJunta de Andalucía 2012/FQM 107
Cochlear Implantation in Patients with Neurofibromatosis Type 2 and Patients with Vestibular Schwannoma in the Only Hearing Ear
Cochlear implants are a new surgical option in the hearing rehabilitation of patients with neurofibromatosis type 2 (NF2) and patients with vestibular schwannoma (VS) in the only hearing ear. Auditory brainstem implant (ABI) has been the standard surgical treatment for these patients. We performed a literature review of patients with NF2 and patients with VS in the only hearing ear. Cochlear implantation (CI) provided some auditory benefit in all patients. Preservation of cochlear nerve integrity is crucial after VS resection. Results ranged from environmental sound awareness to excellent benefit with telephone use. Promontory stimulation is recommended although not crucial. MRI can be performed safely in cochlear implanted patients
Synthesis of IAN-type N,N-Ligands via Dynamic Kinetic Asymmetric Buchwald-Hartwig Amination
The Pd-catalyzed coupling of racemic heterobiaryl bromides, triflates, or nonaflates with aryl/alkyl primary amines using QUINAP as the ligand provides the corresponding axially chiral heterobiaryl amines with excellent yields and enantioselectivities. Reactivity and structural studies of neutral and cationic oxidative addition intermediates support a dynamic kinetic asymmetric amination mechanism based on the labilization of the stereogenic axis in the latter and suggest that coordination of the amine to the Pd center is the stereodetermining step.Ministerio de Ciencia e Innovación CTQ2013-48164-C2-1-P, CTQ2013-48164-C2-2-P, RYC-2013-12585 for A.R.European FEDER FundsJunta de Andalucía 2012/FQM 1078
Solvent-free synthesis of quaternary α-hydroxy α-trifluoromethyl diazenes: the key step of a nucleophilic formylation strategy
An efficient, scalable and operationally simple one-pot, 2-step strategy for the nucleophilic formylation of
trifluoromethyl ketones is presented. The key step is an unprecedented diaza-carbonyl-ene reaction of
formaldehyde tert-butyl hydrazone and trifluoromethyl ketones under solvent-free conditions. This reaction
proved to be very fast, clean and high-yielding, affording densely functionalised α-hydroxy
α-trifluoromethyl diazenes. The ensuing diazene-to-aldehyde transformation, avoiding protection/deprotection
reactions and chromatographic purifications, and subsequent derivatizations in a one-pot
fashion provide a direct entry to a variety of useful trifluoromethylated building blocks.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).This work was supported by the Ministerio de Economía y
Competitividad of Spain (CTQ2013-48164-C2-1-P, CTQ2013-48164-C2-2-P, and predoctoral fellowship to E. M.), European FEDER funds and the Junta de Andalucía (Grant 2012/FQM 1078). D. M. acknowledges Universidad de Sevilla for a postdoctoral
contract.Peer reviewe
Dynamic Kinetic Resolution of Hetero biaryl Ketones by Zinc- Catalyzed Asymmetr ic Hydrosil ylation
Adiastereo-
and
highly
enantioselective
dynamic
kinetic
resolution
(DKR)
of configurationally
labile
hetero-
biaryl
ketones
is described.
The
DKR
proceeds
by zinc-
catalyze
dhydrosilylation
of the carbonyl
group
,thus leading
to
secondary
alcohols
bearing
axial
and
central
chirality
.The
strategy
relies
on the labilization
of the stereogenic
axis
that
takes
place
thanks
to aLewis
acid–base
interaction
between
anitrogen
atom
in the heterocycle
and
the ketone
carbonyl
group
.The synthetic
utility
of the methodology
is demonstrated
through
stereospecific
transformations
into either
N,N-ligands
or appealing
axially
chiral,
bifunctional
thiourea
organocata-
lysts.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P, CTQ2016-76908-C2-2-P, contract RYC-2013-12585)European FEDER FundsJunta de Andalucía (Grant 2012/FQM 10787)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement n 8 8 291780
50 year trends in nitrogen use efficiency of world cropping systems: the relationship between yield and nitrogen input to cropland
International audienceNitrogen (N) is crucial for crop productivity. However, nowadays more than half of the N added to cropland is lost to the environment, wasting the resource, producing threats to air, water, soil and biodiversity, and generating greenhouse gas emissions. Based on FAO data, we have reconstructed the trajectory followed, in the past 50 years, by 124 countries in terms of crop yield and total nitrogen inputs to cropland (manure, synthetic fertilizer, symbiotic fixation and atmospheric deposition). During the last five decades, the response of agricultural systems to increased nitrogen fertilization has evolved differently in the different world countries. While some countries have improved their agro-environmental performances, in others the increased fertilization has produced low agronomical benefits and higher environmental losses. Our data also suggest that, in general, those countries using a higher proportion of N inputs from symbiotic N fixation rather than from synthetic fertilizer have a better N use efficiency
A Dynamic Kinetic Asymmetric Heck Reaction for the Simultaneous Generation of Central and Axial Chirality
A highly diastereo- and enantioselective, scalable Pd-catalyzed dynamic kinetic asymmetric Heck reaction of heterobiaryl sulfonates with electron-rich olefins is described. The coupling of 2,3-dihydrofuran or N-boc protected 2,3-dihydropyrrole with a variety of quinoline, quinazoline, phthalazine, and picoline derivatives takes place with simultaneous installation of central and axial chirality, reaching excellent diastereo- and enantiomeric excesses when in situ formed [Pd0/DM-BINAP] was used as the catalyst, with loadings reduced down to 2 mol % in large scale reactions. The coupling of acyclic, electron-rich alkenes can also be performed using a [Pd0/Josiphos ligand] to obtain axially chiral heterobiaryl α-substituted alkenes in high yields and enantioselectivities. Products from Boc-protected 2,3-dihydropyrrole can be easily transformed into N,N ligands or appealing axially chiral, bifunctional proline-type organocatalysts. Computational studies suggest that a β-hydride elimination is the stereocontrolling step, in agreement with the observed stereochemical outcome of the reaction.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P; CTQ2016-76908-C2-2-P; CTQ2016-78083-P; RYC-2013-12585)European Commission (FEDER Programme)Junta de Andalucía (Grant 2012/FQM 10787)Universidad de Sevilla (Grant No. 1800511201)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement nº 291780
Avances en el diagnóstico molecular y en el tratamiento de los gliomas de bajo grado en la edad pediátrica
Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Pediatría. Fecha de lectura: 12-09-2017Esta tesis tiene embargado el acceso al texto completo hasta el 12-03-201
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