906 resultados para TERTIARY PHOSPHINES
Resumo:
We estimate the economic impacts of irrigation using the panel data set from rural Thailand. We employed difference-in-differences estimation and showed that tertiary irrigation has unexpected impacts. Contrary to the local experts predicitions that it should have substantial productivity impacts as it allows better water controls for farmers, we found largely zero profitability impacts. Another unexpected finding is that, while profitability is not affected, we see an increase in cultivation probability with the construction of tertiary canals. This is observed in both wet and dry seasons. This finding suggests that Thai farmers are willing to expand operation scale once they get water.
Resumo:
Geological storage of CO2 is nowadays internationally considered as the most effective method for greenhouse gas emission mitigation, in order to minimize its effects on the global climatology. One of the main options is to store the CO2 in deep saline aquifers at more than 800 m depth, because it achieves its supercritical state. Among the most important aspects concerning the performance assessment of a deep CO2 geological repository is the evaluation of the CO2 leakage rate from the chosen storage geological formation. Therefore, it is absolutely necessary to increase the knowledge on the interaction among CO2, storage and sealing formations, as well as on the flow paths for CO2 and the physico-mechanical resistance of the sealing formation. Furthermore, the quantification of the CO2 leakage rate is essential to evaluate its effects on the environment. One way to achieve this objective is to study of CO2 leakage on natural analogue systems, because they can provide useful information about the natural performance of the CO2, which can be applied to an artificial CO2 geological storage. This work is focused on the retention capacity of the cap-rock by measuring the diffuse soil CO2 flux in a site selected based on: i) the presence of a natural and deep CO2 accumulation; ii) its structural geological characteristics; and iii) the nature of the cap-rocks. This site is located in the so-called Mazarrón-Gañuelas Tertiary Basin, in the Guadalentin Valley, province of Murcia (Spain) Therefore the main objective of this investigation has been to detect the possible leakages of CO2 from a deep saline aquifer to the surface in order to understand the capability of this area as a natural analogue for Carbon Capture and Sequestration (CCS). The results obtained allow to conclude that the geological sealing formation of the basin seems to be appropriate to avoid CO2 leakages from the storage formation.
Resumo:
Geological storage of CO2 is nowadays internationally considered as the most effective method for greenhouse gas emission mitigation, in order to minimize its effects on the global climatology. One of the main options is to store CO2 in deep saline aquifers at more than 800m depth, because it reaches its supercritical state. Study of the CO2 natural accumulations as natural analogues of an artificial CO2 storage is very useful in order to understand the CO2 long term behaviour and thus to predict its possible impact on the surficial environment and life. Therefore the main objective of this work is to detect the affection of the CO2 leakages from a deep saline aquifer on the shallow aquifers, all of them located in the Gañuelas-Mazarrón Tertiary basin (Province of Murcia, Spain). This CO2 storage and leakage natural system can be analogous to an artificial CO2 storage with leakage phenomena. In order to reach these objectives, groundwaters from different aquifers in the site have been sampled and analysed for major elements, free and dissolved gases and stable isotopes, particularly ∂ 13 C and 3 He/ 4 He. The results obtained allow to conclude that this natural system is an interesting example of natural analogue for an artificial CO2 storage affected by leakage processes because the shallow fresh aquifers in the site are polluted by CO2 from the deep saline aquifer as a consequence of an intensive over-exploitation of these freshwater aquifers
Resumo:
Abstract: This paper summarizes the evolution of different subjects of English for Specific Purposes and English for Academic and Professional Purposes. The aim here is to show a continuum of changes that have not started and nished in one subject alone but affect the whole curriculum. After the discussion section where advantages and drawbacks of the changes introduced are analyzed, we arrive at some conclusions regarding this ve year period of development in the approach to the teaching and learning of the specific or academic English language in the Escuela Universitaria de Ingeniería Técnica de Telecomunicación, Universidad Politécnica de Madrid. Resumen: Este trabajo resume la evolución que han experimentado distintas asignaturas de Inglés para Fines Especí cos e Inglés para Fines Académicos y Profesionales. El objetivo principal es mostrar cómo el esfuerzo por mejorar las asignaturas afecta al currículo como un todo y no sólo a cada una de las asignaturas. Tras el análisis de algunas de las ventajas e inconvenientes de los cambios introducidos, se alcanzan algunas conclusiones sobre la evolución que han sufrido este tipo de asignaturas durante los últimos cinco años en la Escuela Universitaria de Ingeniería Técnica de Telecomunicación, Universidad Politécnica de Madrid.
Resumo:
In the framework of a global investigation of the Spanish natural analogues of CO2 storage and leakage, four selected sites from the Mazarrón?Gañuelas Tertiary Basin (Murcia, Spain) were studied for computing the diffuse soil CO2 flux, by using the accumulation chamber method. The Basin is characterized by the presence of a deep, saline, thermal (?47 ?C) CO2-rich aquifer intersected by two deep geothermal exploration wells named ?El Saladillo? (535 m) and ?El Reventón? (710 m). The CO2 flux data were processed by means of a graphical?statistical method, kriging estimation and sequential Gaussian simulation algorithms. The results have allowed concluding that the Tertiary marly cap-rock of this CO2-rich aquifer acts as a very effective sealing, preventing any CO2 leak from this natural CO2 storage site, being therefore an excellent scenario to guarantee, by analogy, the safety of a CO2 storage.
Resumo:
The aim of this research is to obtain the absorption rate of CO2 into aqueous solution of N,N- di methyl ethanolamine and into aqueous solution of Triethylene diamine and to demonstrate the importance of absorption of CO2 in nowadays by discussing global warming and greenhouse effect. It is also discussed the current situation of China focusing in the latest steps this country has recently made. In the experimental part of this work, the two tertiary amine solutions will absorb CO2 in a Lewis type cell, measuring the pressure change during the reactions take place. The temperature will be between 35 degree and 70 degree Celsius. The results of both solutions, concentrations of 0.5 and 1.0 mol per liter, are discussed and a single value of the rate constant is given for the first time along with some others parameters.
Resumo:
A previous study of the retinitis pigmentosa mutation L125R and two designed mutations at this site, L125A and L125F, showed that these mutations cause partial or total misfolding of the opsins expressed in COS cells from the corresponding mutant opsin genes. We now report on expression and characterization of the opsins from the following retinitis pigmentosa mutants in the transmembrane domain of rhodopsin that correspond to six of the seven helices: G51A and G51V (helix A), G89D (helix B), A164V (helix D), H211P (helix E), P267L and P267R (helix F), and T297R (helix G). All the mutations caused partial misfolding of the opsins as observed by the UV/visible absorption characteristics and by separation of the expressed opsins into fractions that bound 11-cis-retinal to form the corresponding mutant rhodopsins and those that did not bind 11-cis-retinal. Further, all the mutant rhodopsins prepared from the above mutants, except for G51A, showed strikingly abnormal bleaching behavior with abnormal metarhodopsin II photointermediates. The results show that retinitis pigmentosa mutations in every one of the transmembrane helices can cause misfolding of the opsin. Therefore, on the basis of these and previous results, we conclude that defects in the packing of the transmembrane helices resulting from these mutations are relayed to the intradiscal domain, where they cause misfolding of the opsin by inducing the formation of a disulfide bond other than the native Cys-110—Cys-187 disulfide bond. Thus, there is coupling between packing of the helices in the transmembrane domain and folding to a tertiary structure in the intradiscal domain.
Resumo:
Thyrotropin-releasing hormone (TRH) is a brain hypothalamic hormone that regulates thyrotropin (TSH) secretion from the anterior pituitary and is ubiquitously distributed throughout the brain and other tissues including pancreas. To facilitate studies into the role of endogenous TRH, we have used homologous recombination to generate mice that lack TRH. These TRH−/− mice are viable, fertile, and exhibit normal development. However, they showed obvious hypothyroidism with characteristic elevation of serum TSH level and diminished TSH biological activity. Their anterior pituitaries exhibited an apparent decrease in TSH immunopositive cells that was not due to hypothyroidism. Furthermore, this decrease could be reversed by TRH, but not thyroid hormone replacement, suggesting a direct involvement of TRH in the regulation of thyrotrophs. The TRH−/− mice also exhibited hyperglycemia, which was accompanied by impaired insulin secretion in response to glucose. These findings indicate that TRH−/− mice provide a model of exploiting tertiary hypothyroidism, and that TRH gene abnormalities cause disturbance of insulin secretion resulting in marked hyperglycemia.
Resumo:
For efficient ligand binding, integrins must be activated. Specifically, a conformational change has been proposed in a ligand binding domain present within some integrins, the inserted (I) domain [Lee, J., Bankston, L., Arnaout, M. & Liddington, R. C. (1995) Structure (London) 3, 1333–1340]. This proposal remains controversial, however, despite extensive crystal structure studies on the I domain [Lee, J., Bankston, L., Arnaout, M. & Liddington, R. C. (1995) Structure (London) 3, 1333–1340; Liddington, R. & Bankston, L. (1998) Structure (London) 6, 937–938; Qu, A. & Leahy, D. J. (1996) Structure (London) 4, 931–942; and Baldwin, E. T., Sarver, R. W., Bryant, G. L., Jr., Curry, K. A., Fairbanks, M. B., Finzel, B. C., Garlick, R. L., Heinrikson, R. L., Horton, N. C. & Kelly, L. L. (1998) Structure (London) 6, 923–935]. By defining the residues present in the epitope of a mAb against the human Mac-1 integrin (αMβ2, CD11b/CD18) that binds only the active receptor, we provide biochemical evidence that the I domain itself undergoes a conformational change with activation. This mAb, CBRM1/5, binds the I domain very close to the ligand binding site in a region that is widely exposed regardless of activation as judged by reactivity with other antibodies. The conformation of the epitope differs in two crystal forms of the I domain, previously suggested to represent active and inactive receptor. Our data suggests that conformational differences in the I domain are physiologically relevant and not merely a consequence of different crystal lattice interactions. We also demonstrate that the transition between the two conformational states depends on species-specific residues at the bottom of the I domain, which are proposed to be in an interface with another integrin domain, and that this transition correlates with functional activity.
Resumo:
Analysis of the 2.4-Å resolution crystal structure of the large ribosomal subunit from Haloarcula marismortui reveals the existence of an abundant and ubiquitous structural motif that stabilizes RNA tertiary and quaternary structures. This motif is termed the A-minor motif, because it involves the insertion of the smooth, minor groove edges of adenines into the minor groove of neighboring helices, preferentially at C-G base pairs, where they form hydrogen bonds with one or both of the 2′ OHs of those pairs. A-minor motifs stabilize contacts between RNA helices, interactions between loops and helices, and the conformations of junctions and tight turns. The interactions between the 3′ terminal adenine of tRNAs bound in either the A site or the P site with 23S rRNA are examples of functionally significant A-minor interactions. The A-minor motif is by far the most abundant tertiary structure interaction in the large ribosomal subunit; 186 adenines in 23S and 5S rRNA participate, 68 of which are conserved. It may prove to be the universally most important long-range interaction in large RNA structures.
Resumo:
PCR amplification of template DNAs extracted from mixed, naturally occurring microbial populations, using oligonucleotide primers complementary to highly conserved sequences, was used to obtain a large collection of diverse RNase P RNA-encoding genes. An alignment of these sequences was used in a comparative analysis of RNase P RNA secondary and tertiary structure. The new sequences confirm the secondary structure model based on sequences from cultivated organisms (with minor alterations in helices P12 and P18), providing additional support for nearly every base pair. Analysis of sequence covariation using the entire RNase P RNA data set reveals elements of tertiary structure in the RNA; the third nucleotides (underlined) of the GNRA tetraloops L14 and L18 are seen to interact with adjacent Watson-Crick base pairs in helix P8, forming A:G/C or G:A/U base triples. These experiments demonstrate one way in which the enormous diversity of natural microbial populations can be used to elucidate molecular structure through comparative analysis.