Intramolecular C-H oxidative addition to iridium(i) triggered by trimethyl phosphite in N, N'-diphosphanesilanediamine complexes

The reaction of Ir(SiNP)(cod)]PF6] (1]PF6]) and of IrCl(SiNP)(cod) (5) (SiNP = SiMe2{N(4-C6H4CH3)PPh2}2) with trimethyl phosphite affords the iridium(iii) derivatives of the formula IrHClx(SiNP-H){P(OMe)3}2-x](1-x)+ (x = 0, 3+; x = 1, 6) containing the ¿3C, P, P'-coordinated SiNP-H ligand (SiNP-H = Si(CH2)(CH3){N(4-C6H4CH3)PPh2}2). The thermally unstable pentacoordinated cation Ir(SiNP){P(OMe)3}(cod)]+ (2+) has been detected as an intermediate of the reaction and has been fully characterised in solution. Also, the mechanism of the C-H oxidative addition has been elucidated by DFT calculations showing that the square planar iridium(i) complexes of the formula IrClx(SiNP){P(OMe)3}2-x](1-x)+ (x = 0, 4+; x = 1, 7) should be firstly obtained from 2+ and finally should undergo the C-H oxidative addition to iridium(i) via a concerted intramolecular mechanism. The influence of the counterion of 2+ on the outcome of the C-H oxidative addition reaction has also been investigated

Impact of invasive bees on plant-pollinator interactions and reproductive success of plant species in mixed Nothofagus antarctica forests

Invasive social bees can alter plant-pollinator interactions with detrimental effects on both partners. However, most studies have focused on one invasive bee species, while the interactions among two or more species remain poorly understood. Also, many study sites had a history of invasive bees, being hard to find sites with historical low abundances. In Patagonia, Bombus ruderatus (F.) invasion begun in 1993 and B. terrestris (L.) in 2006. Though honey bees (Apis mellifera L.) introduction started in 1859, their density is still low in some parts. By experimentally increasing honey bee densities, we evaluated the effect of honey bees and bumblebees floral visitation on native pollinator floral visitation, pollen deposition, and reproductive success of three plant species in mixed Nothofagus antarctica forests of northern Patagonia: Oxalis valdiviensis, Mutisia spinosa and Cirsium vulgare. Our results show that exotic bees became the main floral visitors. No negative association was found between invasive bee and native pollinator visitation rates, but there was evidence of potential competition between honey bees and bumblebees. Floral neighborhood diversity played an important role in pollinator behavior. Conspecific pollen deposition was high for all species, while deposition of heterospecific pollen was very high in M. spinosa and C. vulgare. Not as expected, honey bees visitation rate had a negative effect on heterospecific pollen deposition in C. vulgare. For O. valdiviensis, exotic visitation rates increased conspecific pollen deposition, which was positively related to reproductive success. Although exotic bees became main floral visitors, their contribution to reproductive success was only clear for one species.info:eu-repo/semantics/acceptedVersio

RADIOTELEMETRÍA GPS: APLICACIÓN EN EL MONITOREO DEL GANADO CAPRINO EN LA RESERVA DE LA BIOSFERA DE TEHUACÁN-CUICATLÁN, OAXACA, MÉXICO

Objective: 1) To describe the radio-telemetry technique for study wildlife; specifically, using the global positioning system  (GPS); and 2) to exemplify the use of this technique with the domestic goats in a location of the Tehuacán-Cuicatlán Biosphere Reserve, Oaxaca.Design/methodology/approach: Goat herds were monitored using GPS radio-telemetry in order to know the spatial and temporal movements in the tropical dry habitats. Specifically, daily distances traveled and foraging areas were estimated using the R packages adehabitatLT and adehabitatHR, respectively.Results: The largest herd (90 individuals) traveled 3.9±.2 (SD) km/day during the rainy season of 2017, and 4.2±2.1 km during the dry season of 2018. The estimated foraging area was 1.44 km2 during the rainfall season, and 2.29 km2 during the dry season.Limitations of the study/implications: The radio-telemetry is a precise but expense technology and for some wildlife species, it is difficult to trap individuals in order to equip and track individuals.Findings/conclusions: However, the radio-telemetry allow answering relevant questions about animal behavior. The data obtained with this technology provides useful information for the development of management plans. For example, we are studying the possible competition between goats and wild ungulates as white-tailed deer. GPS could help to obtain relevant data in this topic.Objetivo: 1) Describir la técnica de radiotelemetría para estudiar la vida silvestre; específicamente, usando el sistema de posicionamiento global (GPS); y 2) ejemplificar el uso de esta técnica con las cabras domésticas en una localidad de la Reserva de la Biosfera Tehuacán-Cuicatlán, Oaxaca.Diseño/metodología/aproximación: Los rebaños de cabras fueron monitoreados usando radiotelemetría GPS para conocer los movimientos espaciales y temporales en hábitats tropicales secos. Específicamente, las distancias diarias recorridas y las áreas de forrajeo se estimaron utilizando los paquetes R adehabitatLT y adehabitatHR, respectivamente.Resultados: El rebaño más grande (90 individuos) viajó 3.9±1.2 (SD) km/día durante la estación lluviosa de 2017 y 4.2±2.1 km durante la estación seca de 2018. El área de forrajeo estimada fue de 1.44 km2 durante la temporada de lluvias y 2.29 km2 durante la temporada seca.Limitaciones del estudio/implicaciones: La radiotelemetría es una tecnología precisa, pero costosa y para algunas especies de fauna silvestre es difícil atrapar individuos para equiparlos y rastrearlos.Hallazgos/conclusiones: Sin embargo, la radiotelemetría permite responder preguntas relevantes sobre el comportamiento animal. Los datos obtenidos con esta tecnología proporciona información útil parael desarrollo de planes de gestión. Por ejemplo, estamos estudiando la posible competencia entre cabras y ungulados silvestres como el venado cola blanca. El GPS podría ayudar a obtener datos relevantesen este tema

Electromejoramiento de suelos del Valle del Cauca afectados por sales.

Maestría en CienciasMaestrí

Uretroplastia de sustitución con doble injerto de mucosa oral como opción terapéutica para pacientes con estenosis de uretra bulbar asociada a UroLume®

ResumenEl UroLume® o endoprótesis uretral fue concebido como un dispositivo de fácil colocación para pacientes con estenosis uretral bulbar recurrente. Con el paso del tiempo se demostró que ocasionaba más complicaciones que beneficios por lo que se abandonó su uso. Sin embargo, se generó un grupo de pacientes con estenosis uretral compleja que necesitaban múltiples tratamientos quirúrgicos con resultados poco favorecedores. Con la divulgación a finales de la década de los 90 del uso de injertos de mucosa oral para el tratamiento de estenosis uretral se inició una nueva etapa en la búsqueda de un tratamiento definitivo para este tipo de pacientes. El objetivo del artículo es presentar una técnica quirúrgica no descrita en la literatura para el tratamiento de estenosis uretral bulbar asociada a UroLume®. Se describe el caso de un paciente masculino de 71 años de edad con estenosis uretral bulbar secundaria a resección transuretral de próstata al cual le fue colocado un UroLume® hace 8 años presentando reestenosis uretral, tratado con múltiples dilataciones uretrales. Mediante un abordaje perineal se retiró la endoprótesis en su totalidad, en base a las características locales de los tejidos se decidió colocar un doble injerto de mucosa oral dorsal inlay y ventral onlay con resultados exitosos a 6 meses de seguimiento.AbstractUroLume®, or urethral endoprosthesis, was conceived as an easy placement device for patients with recurrent bulbar urethral stricture. With the passage of time, it was shown to cause more complications than benefits and its use was discontinued. However, it created a group of patients with complex urethral stricture that required multiple surgical treatments with unsatisfactory results. The widespread use at the end of the 1990s of buccal mucosa grafts for the treatment of urethral stricture began a new stage in the search for a definitive treatment for this type of patient.The aim of our article was to present a surgical technique for the treatment of UroLume®-associated bulbar urethral stricture that has not been described in the literature.A 71-year-old man presented with bulbar urethral stricture secondary to transurethral resection of the prostate who, 8 years ago, had UroLume® placement. He presented with another urethral stricture and was treated with numerous urethral dilations. Through the perineal approach, the endoprosthesis was completely removed, and based on the local tissue characteristics, a dorsal inlay and ventral onlay double buccal mucosa graft was placed with successful results at the 6th month of follow-up

Divergent reactivity of 2-vinylpyridine and 1-vinylpyrazole in rhodium-phosphine systems: C-H activation and dinuclear chemistry

The Rh-I-Rh-III mixed valence dinuclear complex Rh-2-Cl-2(mu-H)(mu-eta(2),kappa(2)-C, N-NC5H4-2-(Z)CH=CH)( PPhMe2)(3) has been prepared by reaction of [Rh(mu-Cl)(eta(2)-coe)(2)](2) with 2-vinylpyridine in the presence of dimethylphenylphosphine as a result of C-H activation of the terminal olefinic proton. The X- ray structure presents anagostic Rh center dot center dot center dot HC and pi-pi interactions between aromatic rings. In contrast, 1-vinylpyrazole does not undergo a C-H activation process, resulting in the formation of dinuclear species supported by 1 vinylpyrazole bridges. Anagostic Rh center dot center dot center dot HC interactions and CH center dot center dot center dot Cl hydrogen bonds are responsible for the 3D packing of the complex. El complejo dinuclear de valencia mixta RhI-RhIII Rh2-Cl2(µ-H)(µ-¿2,¿2-C,N-NC5H4-2-(Z)CH=CH)(PPhMe2)3 ha sido preparado por reacción de [Rh(µ-Cl)(¿2-coe)2]2 con 2-vinilpiridina en presencia de dimetilfenilfosfina, como resultado de la activación C-H del protón terminal de la olefina. La estructura de rayos-X presenta enlaces anagósticos Rh···HC, así como interacciones p-p entre anillos aromáticos. Por otro lado, la reacción con 1-vinilpirazol no da lugar a una activación C-H sino que se observa la formación de una especie dinuclear soportada por ligandos 1-vinilpirazol puente. Diferentes interacciones anagósticas Rh···HC y de enlace de hidrógeno CH···Cl son responsables del empaquetamiento tridimensional del complejo

Time Series

This paper first shows that survey-based expectations (SBE) outperform standard time series models in U.S. quarterly inflation out-of-sample prediction and that the term structure of survey-based inflation forecasts has predictive power over the path of future inflation changes. It then proposes some empirical explanations for the forecasting success of survey-based inflation expectations. We show that SBE pool a large amount of heterogeneous information on inflation expectations and react more flexibly and accurately to macro conditions both contemporaneously and dynamically. We illustrate the flexibility of SBE forecasts in the context of the recent financial crisis

Cardiometabolic and Cardiovascular Complications of Obesity in Children

The rise in obesity in both children and adults has made obesity one of the biggest public health problems of this century. Obesity along with other factors such as hypertension, insulin resistance, dyslipidemia and diabetes mellitus are risk factors for the development of cardiovascular diseases. Overweight and/or obesity during childhood and its maintenance until adult life has been associated with early stages of cardiovascular disease. For this reason, the aim of this study is to revise the state of the art of cardiometabolic and cardiovascular complications related with overweight and/or obesity in children and adolescents. The first consequence of weight gain is an increase in adipose tissue, with different distribution depending on the sex. The excess of fat mass entails dysfunction of adipose tissue with an altered secretion of adipokines and instauration of a proinflammatory environment, which may derive in metabolic syndrome condition. The increase of adipose tissue along with an increase in sympathetic nervous system, triggers an increased left ventricular mass and with a reduced diastolic function. Therefore, obesity should be prevented from the early stages of life, in order to avoid obesity itself and the metabolic disturbances that could undermine quality of life further on

Hydroformylation of synthetic naphtha catalyzed by a dinuclear gem-dithiolato-bridged rhodium(I) complex

This work focuses on the use of a gem-dithiolato-bridged rhodium(I) Rh 2(µ-S 2CBn 2)(cod) 2 complex (cod = 1,5-cyclooctadiene, Bn 2CS 2 2- = 1,3-diphenyl-2,2-dithiolatopropane) dissolved in toluene in the presence of monodentate phosphite P-donor ligand (P(OPh) 3) under carbon monoxide/hydrogen (1:1, syngas) atmosphere as an effective catalyst for hydroformylation of some olefins (oxo-reactions). The capability of this system to catalyze the hydroformylation of hex-1-ene, cyclohexene, 2,3-dimethyl-but-1-ene and 2-methyl-pent-2-ene and their quaternary mixture (synthetic naphtha) has been demonstrated. This innovative method to perform the in situ hydroformylation of the olefins present in naphthas to oxygenated products would be a promissory work for a future industrial catalytic process applicable to gasoline improving based on oxo-reactions. An important observation is that variation of CO/H 2 pressure (6.8-34.0 atm), temperature (60-80 oC), reaction time (2-10 h), rhodium concentration ((1.0-1.8)x10 -3 mol/L) affect hydroformylation reaction rates. Optimal conversion to oxygenated products were achieved under Rh = 1.8 x10 -2 mol/L, P(CO/H 2) = 34 atm (CO/H 2 = 1:1) at 80 oC for 10 h