National Autonomous University of 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.

TeV Gamma-ray Sources from a survey of the Galactic Plane with Milagro

Abstract: A survey of Galactic gamma-ray sources at a median energy of ~20 TeV has been performed using the Milagro Gamma-Ray Observatory. Eight candidate sources of TeV emission are detected with pretrial significances >4.5 σ in the region of Galactic longitude l [30°, 220°] and latitude b [-10°, 10°]. Four of these sources, including the Crab Nebula and the recently published MGRO J2019+37, are observed with significances >4 σ after accounting for the trials. All four of these sources are also coincident with EGRET sources. Two of the lower significance sources are coincident with EGRET sources, and one of these sources is Geminga. The other two candidates are in the Cygnus region of the Galaxy. Several of the sources appear to be spatially extended. The fluxes of the sources at 20 TeV range from ~25% of the Crab flux to nearly as bright as the Crab.

Unravelling the regulatory mechanisms that modulate the MEP pathway in higher plants

Abstract: The methyl-D-erythritol 4-phosphate pathway is responsible for the biosynthesis of a substantial number of natural compounds of biological and biotechnological importance In recent years, this pathway has become an obvious target to develop new herbicides and antimicrobial drugs In addition, the production of a variety of compounds of medical and agricultural interest may be possible through the genetic manipulation of this pathway To this end, a complete understanding of the molecular mechanisms that regulate this pathway is of tremendous importance Recent data have accumulated that show some of the multiple mechanisms that regulate the methyl-D-erythritol 4-phosphate pathway in plants In this review we will describe some of these and discuss their implications It has been demonstrated that 1-deoxy-D-xylulose-5-phosphate synthase (DXS), the first enzyme of this route, plays a major role in the overall regulation of the pathway A small gene family codes for this enzyme in most of the plants which have been analysed so far, and the members of these gene families belong to different phylogenetic groups Each of these genes exhibits a distinct expression pattern, suggesting unique functions One of the most interesting regulatory mechanisms recently described for this pathway is the post-transcriptional regulation of the level of DXS and DXR proteins In the case of DXS, this regulation appears conserved among plants, supporting its importance The evidence accumulated suggests that this regulation might link the activity of this pathway with the plant's physiological conditions and the metabolic demand for the final products of this route

Review on ammonia as a potential fuel: from synthesis to economics

Abstract: Ammonia, a molecule that is gaining more interest as a fueling vector, has been considered as a candidate to power transport, produce energy, and support heating applications for decades. However, the particular characteristics of the molecule always made it a chemical with low, if any, benefit once compared to conventional fossil fuels. Still, the current need to decarbonize our economy makes the search of new methods crucial to use chemicals, such as ammonia, that can be produced and employed without incurring in the emission of carbon oxides. Therefore, current efforts in this field are leading scientists, industries, and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis, this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector, moving through all of the steps in the production, distribution, utilization, safety, legal considerations, and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed, thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works, this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further, the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes, legal barriers that will be faced to achieve its deployment, safety and environmental considerations that impose a critical aspect for acceptance and wellbeing, and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein, this work sets the principles, research, practicalities, and future views of a transition toward a future where ammonia will be a major energy player.