986 resultados para HYPERVALENT IODINE(III) REAGENT
Resumo:
En aquest treball s'aporten dades sobre la presència de nous tàxons a la plana occidental catalana, i que impliquen, en la majoria dels casos, ampliar de manera notable l'àrea de distribució de l'espècie. Són de destacar Cheirolophus intybaceus (Lam.) Dostál, Iris spuria L., Lathyrus annuus L., Phagnalon rupestre (L.) DC., Succisa pratensis Moench, Trigonella gladiata Steven ex Bieb. i Orchis laxiflora Lam. subsp. palustris (Jacq.) Bonnier & Layens.
Resumo:
Se presentan las ofrendas repetidas de jarras usadas conteniendo huevos, porciones de gallináceas y ovicápridos junto a los muros exteriores de dos villas romanas próximas a Emporiae. Se interpretan como un ritual expiatorio y lustral ofrendado a los Manes familiares.
Resumo:
The use of iodine as a catalyst and either acetic or trifluoroacetic acid as a derivatizing reagent for determining the enantiomeric composition of acyclic and cyclic aliphatic chiral alcohols was investigated. Optimal conditions were selected according to the molar ratio of alcohol to acid, the reaction time, and the reaction temperature. Afterwards, chiral stability of chiral carbons was studied. Although no isomerization was observed when acetic acid was used, partial isomerization was detected with the trifluoroacetic acid. A series of chiral alcohols of a widely varying structural type were then derivatized with acetic acid using the optimal conditions. The resolution of the enantiomeric esters and the free chiral alcohols was measured using a capillary gas chromatograph equipped with a CP Chirasil-DEX CB column. The best resolutions were obtained with 2-pentyl acetates (α = 3.00) and 2-hexyl acetates (α = 1.95). This method provides a very simple and efficient experimental workup procedure for analyzing chiral alcohols by chiral-phase GC.
Resumo:
En el segundo artículo, de una serie de tres destinados a una síntesis del estado del conocimiento hidráulico y geomorfológico acerca de ríos de montaña, se expusieron las principales características hidráulicas del flujo de baja concentración de sedimento. En este último artículo, se tratarán los rasgos geomorfólogicos que caracterizan a los ríos de montaña de material grueso de forma específica frente a los ríos de llanura de sedimento fino.
Resumo:
En este artículo se analiza lingüísticamente la toponimia documental que pertenece a los núcleos de población del Ayuntamiento de Foradada del Toscar. Para ello partimos, principalmente, de la lectura de dos fuentes documentales inéditas: los Amillaramientos con rectificaciones hasta el año 1879 (Am.) conservados en el Archivo Histórico Provincial de Huesca (AHPH) y, sobre todo, los Protocolos Notariales de Pedro de Guart (Protocolos) conservados en el Archivo Capitular de Lérida (ACL). El análisis se realiza desde el punto de vista tradicional de la toponimia diacrónica. La mayoría de los topónimos estudiados proceden de una base lingüística latina; otros, en cambio, están relacionados con las lenguas prerromanas (barza, clot, coma, por ejemplo) y con el elemento lingüistico vasco (Gabessaco).
Resumo:
MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is increased by several mechanisms. Precursor tRNA synthesis was increased in multiple tissues without significant effects on mature tRNA levels, implying increased turnover in a futile tRNA cycle. Elevated futile cycling of hepatic lipids was also observed. Metabolite profiling of the liver and skeletal muscle revealed elevated levels of many amino acids and spermidine, which links the induction of autophagy in Maf1(-/-) mice with their extended life span. The increase in spermidine was accompanied by reduced levels of nicotinamide N-methyltransferase, which promotes polyamine synthesis, enables nicotinamide salvage to regenerate NAD(+), and is associated with obesity resistance. Consistent with this, NAD(+) levels were increased in muscle. The importance of MAF1 for metabolic economy reveals the potential for MAF1 modulators to protect against obesity and its harmful consequences.
Resumo:
OBJECTIVE: To assess the iodine status of Swiss population groups and to evaluate the influence of iodized salt as a vector for iodine fortification. DESIGN: The relationship between 24 h urinary iodine and Na excretions was assessed in the general population after correcting for confounders. Single-day intakes were estimated assuming that 92 % of dietary iodine was excreted in 24 h urine. Usual intake distributions were derived for male and female population groups after adjustment for within-subject variability. The estimated average requirement (EAR) cut-point method was applied as guidance to assess the inadequacy of the iodine supply. SETTING: Public health strategies to reduce the dietary salt intake in the general population may affect its iodine supply. SUBJECTS: The study population (1481 volunteers, aged ≥15 years) was randomly selected from three different linguistic regions of Switzerland. RESULTS: The 24 h urine samples from 1420 participants were determined to be properly collected. Mean iodine intakes obtained for men (n 705) and women (n 715) were 179 (sd 68.1) µg/d and 138 (sd 57.8) µg/d, respectively. Urinary Na and Ca, and BMI were significantly and positively associated with higher iodine intake, as were men and non-smokers. Fifty-four per cent of the total iodine intake originated from iodized salt. The prevalence of inadequate iodine intake as estimated by the EAR cut-point method was 2 % for men and 14 % for women. CONCLUSIONS: The estimated prevalence of inadequate iodine intake was within the optimal target range of 2-3 % for men, but not for women.
Resumo:
The emergence of chirality in enantioselective autocatalysis for compounds unable to transform according to the Frank-like reaction network is discussed with respect to the controversial limited enantioselectivity (LES) model composed of coupled enantioselective and non-enantioselective autocatalyses. The LES model cannot lead to spontaneous mirror symmetry breaking (SMSB) either in closed systems with a homogeneous temperature distribution or in closed systems with a stationary non-uniform temperature distribution. However, simulations of chemical kinetics in a two-compartment model demonstrate that SMSB may occur if both autocatalytic reactions are spatially separated at different temperatures in different compartments but coupled under the action of a continuous internal flow. In such conditions, the system can evolve, for certain reaction and system parameters, toward a chiral stationary state; that is, the system is able to reach a bifurcation point leading to SMSB. Numerical simulations in which reasonable chemical parameters have been used suggest that an adequate scenario for such a SMSB would be that of abyssal hydrothermal vents, by virtue of the typical temperature gradients found there and the role of inorganic solids mediating chemical reactions in an enzyme-like role.
Resumo:
Isoetes Durieui Bory. La Selva : Santa Cristina d'Aro, hacia el Torrent de Plana Basarda, Isoelion (A. Bolos, O. Bolos, B r . - B L , F . Q., etc.) ; Sils, al S. de Sant Maurici, 100 m. alt., Isoelicm (leg. Batalla, O. Bolos et Lapraz).