Search results for "uci"
showing 10 items of 5317 documents
A possible structural determinant of selectivity of boldine and derivatives for the alpha 1A-adrenoceptor subtype.
1996
1. The selectivity of action of boldine and the related aporphine alkaloids, predicentrine (9-O-methylboldine) and glaucine (2,9-O-dimethylboldine) and alpha 1-adrenoceptor subtypes was studied by examining [3H]-prazosin competition binding in rat cerebral cortex. WB 4101 and benoxathian were used as selective alpha 1A-adrenoceptor antagonists. 2. In the competition experiments [3H]-prazosin (0.2 nM) binding was inhibited by WB 4101 and benoxathian. The inhibition curves displayed shallow slopes which could be subdivided into high and low affinity components (pKi = 9.92 and 8.29 for WB 4101, 9.35 and 7.94 for benoxathian). The two antagonists recognized approximately 37% of the sites with h…
Conformal measures for multidimensional piecewise invertible maps
2001
Given a piecewise invertible map T:X\to X and a weight g:X\rightarrow\ ]0,\infty[ , a conformal measure \nu is a probability measure on X such that, for all measurable A\subset X with T:A\to TA invertible, \nu(TA)= \lambda \int_{A}\frac{1}{g}\ d\nu with a constant \lambda>0 . Such a measure is an essential tool for the study of equilibrium states. Assuming that the topological pressure of the boundary is small, that \log g has bounded distortion and an irreducibility condition, we build such a conformal measure.
Educar
2015
El presente artículo describe una experiencia de formación en alternancia en un contexto de educación superior; en concreto, a partir de la iniciativa desarrollada por Florida Universitaria, centro adscrito a la Universidad de Valencia. La formación en alternancia implica alternar el aprendizaje entre períodos desarrollados en el centro educativo y momentos desarrollados en el contexto laboral. El objetivo del presente trabajo es identificar una iniciativa que, de forma empírica, muestre cómo estos periodos impactan en el aprendizaje de competencias de los estudiantes. La metodología que se ha aplicado en la experiencia de formación en alternancia se basa en el aprendizaje basado en problem…
Modelling in Physics: A matter of experience?
2012
This study is focused on analyzing experimental results obtained due the use of different types of problem statements. It analyzes characteristics of problem-solving processes in subjects who have different levels of experience in solving physics problems. The problem-solving process is assumed as a process of modeling where different levels of representations are built. It is proposed a comprehension model for Physics problem-solving that assumes the existence of three levels of representation with different ontological elements and different levels of abstraction: A Situation Model (referential, non-abstract world representation of objects and events), a Conceptual-Physics Model (abstract…
Dificultades algebraicas en la resolución de problemas por transferencia
2007
La enseñanza de resolución de problemas en ciencias y matemáticas se realiza en general mediante estrategias de transferencia (transfer): se resuelve y explica un conjunto de problemas y después se pide a los estudiantes que resuelvan otros problemas análogos a los ejemplos trabajados. Los profesores de Secundaria con frecuencia asumen que las relaciones analógicas entre los problemas resueltos y los problemas propuestos son sencillas de comprender y establecer, y atribuyen el fracaso a la falta de dominio de los procedimientos matemáticos de resolución. En este trabajo se realiza un experimento para probar si esta atribución causal es adecuada o no. Los resultados demuestran que la causa p…
Morphogenetic (Mucin Expression) as Well as Potential Anti-Corona Viral Activity of the Marine Secondary Metabolite Polyphosphate on A549 Cells
2020
The mucus layer of the nasopharynx and bronchial epithelium has a barrier function against inhaled pathogens such as the coronavirus SARS-CoV-2. We recently found that inorganic polyphosphate (polyP), a physiological, metabolic energy (ATP)-providing polymer released from blood platelets, blocks the binding of the receptor binding domain (RBD) to the cellular ACE2 receptor in vitro. PolyP is a marine natural product and is abundantly present in marine bacteria. Now, we have approached the in vivo situation by studying the effect of polyP on the human alveolar basal epithelial A549 cells in a mucus-like mucin environment. These cells express mucins as well as the ectoenzymes alkaline phospha…
Over-Oxidation as the Key Step in the Mechanism of the MoCl5-Mediated Dehydrogenative Coupling of Arenes.
2015
Molybdenum pentachloride is an unusually powerful reagent for the dehydrogenative coupling of arenes. Owing to the high reaction rate using MoCl5, several labile moieties are tolerated in this transformation. The mechanistic course of the reaction was controversially discussed although indications for a single electron transfer as the initial step were found recently. Herein, based on a combined study including synthetic investigations, electrochemical measurements, EPR spectroscopy, DFT calculations, and mass spectrometry, we deduct a highly consistent mechanistic scenario: MoCl5 acts as a one-electron oxidant in the absence of TiCl4 and as two-electron oxidant in the presence of TiCl4, bu…
Complexes of Tungsten(VI) with Mucic Acid: a Spectrophotometric and Polarimetric Study in Aqueous Solution
1986
Abstract Spectrophotometric work on mucic acid-W(VI) system shows the formation of three different oxoanion complexes in aqueous solution; their stability is dependent upon pH. One of the complexes is monomeric tungstodimucate and the other two are 2/2 species. An anomalous cryoscopic behaviour, similar to that of W(VI) tartaric system, has been observed for the dimeric complex formed at higher pH. The stoichiometries and conditional dissociation constants have been polarimetrically determined by means of competitive reactions between the mucic and tartaric ligands. 1 H and 13 C NMR spectra have been interpreted for the similar complex species of both mucic and tartaric acids.
FIA-fluorimetric determination of adrenaline in pharmaceutical formulations by oxidation with molecular oxygen
1998
The fluorimetric determination of adrenaline is carried out in a continuous-flow assembly and by means of the molecular dissolved oxygen. The sample solution merges with an NaOH stream, then the resulting mixture is heated at 73 °C and led to the flow-cell of the fluorimeter. The flow-assembly is very simple and the procedure is quick (107 samples h−1) reproducible (R.S.D. 0.6%), selective and suitable to be applied to determination of adrenaline in formulations. Calibrations graph are linear over the ranges 0.05–15 and 20–40 mgl−1.
INFγ stimulates arginine transport through system y+L in human monocytes
2004
Freshly isolated human monocytes transport L-arginine mostly through a sodium independent, NEM insensitive pathway inhibited by L-leucine in the presence, but not in the absence of sodium. Interferon-gamma (IFNgamma) stimulates this pathway, identifiable with system y+L, and markedly enhances the expression of SLC7A7, the gene that encodes for system y+L subunit y+LAT1, but not of SLC7A6, that codes for the alternative subunit y+LAT2. System y+ plays a minor role in arginine uptake by monocytes and the expression of system y+-related genes, SLC7A1 and SLC7A2, is not changed by IFNgamma. These results demonstrate that system y+L is sensitive to IFNgamma.