C–H Insertion via Ruthenium Catalyzed gem-Hydrogenation of 1,3-Enynes

gem-Hydrogenation of an internal alkyne with the aid of [Cp*RuCl]4 as the precatalyst is a highly unorthodox transformation, in which one C atom of the triple bond is transformed into a methylene group, whereas the second C atom gets converted into a ruthenium carbene. In the case of 1,3-enynes bearing a propargylic steering substituent as the substrates, the reaction occurs regioselectively, giving rise to vinyl carbene complexes that adopt interconverting η1/η3-binding modes in solution; a prototypical example of such a reactive intermediate was characterized in detail by spectroscopic means. Although both forms are similarly stable, only the η3-vinyl carbene proved kinetically competent to insert into primary, secondary, or tertiary C–H bonds on the steering group itself or another suitably placed ether, acetal, orthoester, or (sulfon)amide substituent. The ensuing net hydrogenative C–H insertion reaction is highly enabling in that it gives ready access to spirocyclic as well as bridged ring systems of immediate relevance as building blocks for medicinal chemistry. Moreover, the reaction scales well and lends itself to the formation of partly or fully deuterated isotopologues. Labeling experiments in combination with PHIP NMR spectroscopy (PHIP = parahydrogen induced polarization) confirmed that the reactions are indeed triggered by gem-hydrogenation, whereas kinetic data provided valuable insights into the very nature of the turnover-limiting transition state of the actual C–H insertion step

Patterns of scuba diver behaviour to assess environmental impact on marine benthic communities: a suitable tool for management of recreational diving on Benidorm island (Western Mediterranean sea)

Few studies have analyzed the SCUBA divers’ behaviour in the Mediterranean Sea and none of them involved marine unprotected areas. Generally speaking the damage done by individuals is quite low, but the, accumulative effects of these disturbances can cause significant localised destruction of benthic marine organisms. The present study was carried out during the year 2005 on a diving site called La Llosa, on Benidorm Island (Alicante: Western Mediterranean Sea) with more than 7,000 dives per year. Two hundred and seventeen (217) divers were monitored randomly. Each subject was observed underwater for 10 minutes (Rouphael & Inglis, 2001). Samples were randomly collected during the high diving season (June-October). Divers were not aware of this surveillance so as not to interfere with their normal patterns of behaviour. The results showed that 95% of divers came into physical contact with benthic substrata during the 10-min observation period. Fin contact rates were significantly different depending on the diving certification level (Man-Whitney test, p<0.003) detecting the greatest number of contacts within higher diving certification levels (Bonferroni correction). Divers using an underwater light device came intocontact with the substratum significantly more frequently than non-light users (X2, p < 0.022). However, contact rate did not show significant variance across divers using a camera and those who did not (p<0.366). No difference was found between contact rates of divers who were given a briefing and those who were not. Environmental briefing before diving had no effect on the divers’ hand contact rates (X2, p<0.194), which shows a low marine environmental sensitivity level of divers. We concluded that the decrease in scuba divers contact rate would take place given an improvement of environmental awareness, specially among professional divers.Pocos estudios han analizado el comportamiento de los buceadores en el mar Mediterráneo y ninguno se ha centrado en las áreas marinas protegidas. El daño hecho por los buceadores suele ser bajo, pero los efectos acumulados, pueden ser importantes, aunque localizados. Este estudio se llevó a cabo durante el 2005 en una zona de buceo llamada La Llosa, cerca de Benidorm (Alicante, Mediterráneo occidental), con más de 7.000 inmersiones al año. La muestra aleatoria de buceadores llegó al tamaño 217. Se observó a cada buceador durante 10 minutos (Rouphael & Inglis, 2001), en la temporada alta (junio-octubre), de manera que los buceadores no supieran que eran vigilados, para no interferir en su comportamiento habitual. Los resultados mostraron que el 95% de los buceadores entran en contacto físico con los sustratos bentónicos durante el período de observación de 10 min. Las tasas de contacto fueron significativamente diferentes en función del nivel de certificación de buceo (Man-Whitney, p <0,003) detectándose mayor número de contactos en los niveles más altos de certificación de buceo (corrección de Bonferroni). Los buzos que utilizan linterna tuvieron un mayor número de contactos con el sustrato que los que no la usaron (X2, p < 0,022). Pero, no hubo diferentas significativas, entre los que llevaron cámara y no la llevaron (p < 0.366). Tampoco las hubo entre los buzos a los que se dio una conferencia previa a la inmersión y a los que no. La conferencia previa sobre medio ambiente no tuvo efecto sobre el número de contactos con las manos (X2, p < 0,194), lo que demuestra un bajo nivel de sensibilidad de los buceadores ante el medio ambiente marino. Se concluye que la disminución de la tasa de contacto de los buceadores se podría conseguir mejorando su conciencia medioambiental, especialmente la de los buceadores profesionales.Ciencias del Ma

Temporal and spatial variability of prehistoric aquatic resource procurement: a case study from Mesolithic Northern Iberia

Prehistoric shell middens hold valuable evidence of past human–environment interactions. In this study, we used carbon (δ13C) and oxygen (δ18O) stable isotopes of Mytilus galloprovincialis shells excavated from El Perro, La Fragua and La Chora, three Mesolithic middens in Cantabria, Northern Spain, to examine hunter-gatherer subsistence strategies in terms of seasonality and collection areas. Furthermore, we used shell δ18O to reconstruct water temperature during the early Holocene. Stable isotopes reveal a shellfish harvesting diversification trend represented by the gradual establishment of the upper estuaries as new procurement areas and an increase of harvesting mobility in both coastal and in-land sites. These innovations in subsistence strategies during the Mesolithic coincided with major changes in the surrounding environment as attested by the water temperature reconstructions based on δ18O and backed by several global and regional records. Overall, our results show that shell δ13C and δ18O stable isotopes have an underexplored potential as provenance proxies which stimulates their application to the archaeological record to further understand prehistoric human resource procurement and diet

Anti-inflammatory activity of

The anti-inflammatory activity of the chloroform, methanol and aqueous extracts of Wigandia urens and Acalypha alopecuroides were investigated on carrageenan-induced paw edema at doses of 400 mg/kg. The three extracts of W. urens, and the aqueous extract of A. alopecuroides caused significantinhibition of the edema (58.1±6.5% and 63.5±5.4%, respectively). Indomethacin was used as positive control (8 mg/kg), and inhibited edema by 66.3±5.2%. The methanol extract of W. urens and the aqueous extract of A. alopecuroides, at doses of 200 mg/kg, inhibited pellet implantation-induced granuloma formation by 69.4±6.5 and 70.6±6.6%, respectively. These levels of inhibition are higher than those exhibited by naproxen at doses of 50 mg/kg (46.1±7.1%). Both extracts showed activity on adjuvantinduced arthritis in rats, with the best effect being observed after 96 h (82.2±4.6 and 80.6±7.3%, respectively)

An empirical analysis on the operational profile of liquefied natural gas carriers with steam propulsion plants

Liquefied natural gas (LNG) offers negligible NO_{x} and SO_{x} emissions as well as reductions in CO_{2} compared with other liquid hydrocarbons. LNG is a significant player in the global energy mix, with a projection of 40% increase in demand for the next two decades. It is anticipated that the expected rise in demand will cause the fleet of LNG carriers (LNGC) to expand. This work concentrates on steam-powered LNGC, which accounted for 47% of the LNGC fleet in 2018. It performs an empirical analysis of continuous monitoring data that provide high levels of accuracy and transparency. The analysis is done on data collected from 40 LNGCs for over a year to estimate the fleet's operational profile, fuel mix and energy performance. The findings of this work are relevant for bottom-up analysis and simulation models that depend on technical assumptions, but also for emission studies such as the upcoming Fourth International Maritime Organization Greenhouse Gases study

Caracterización de placas de yeso con residuos de espuma de poliuretano reforzadas con fibras de polipropileno

Gypsum plasterboard that incorporates various combinations of polyurethane foam waste and polypropylene fibers in its matrix is studied. The prefabricated material was characterized in a series of standardized tests: bulk density, maximum breaking load under flexion stress, total water absorption, surface hardness, thermal properties, and reaction to fire performance. Polypropylene fibers were added to the polyurethane gypsum composites to improve the mechanical behavior of the plasterboard under loading. The results indicate that increased quantities of polymer waste led to significant reductions in the weight/surface ratio, the mechanical strength and the surface hardness of the gypsum, as well as improving its thermal resistance. The polypropylene fibers showed good adhesion to the polymer and the gypsum matrix, which enhanced the mechanical performance and the absorption capacity of these compounds. The non-combustibility test demonstrated the potential of the new material for use in internal linings.Este artículo presenta un estudio experimental basado en la reutilización de residuos de poliuretano en una matriz de yeso para elaborar una placa de yeso laminado. Las placas fueron caracterizadas mediante los ensayos normalizados de densidad aparente, carga de rotura máxima a flexión, absorción total de agua, dureza superficial y reacción al fuego. Se han introducido fibras de polipropileno en la matriz con el objetivo de aumentar la resistencia mecánica del material. Los resultados muestran que el incremento de residuo polimérico en el material implica importantes reducciones de peso, resistencia mecánica y dureza superficial, a la par que se mejora su resistencia térmica consiguiéndose valores similares a los comerciales. Las fibras de polipropileno mostraron una buena adhesión con el polímero, mejorando el comportamiento mecánico y la capacidad de absorción. El ensayo de reacción al fuego confirmó que los residuos de poliuretano pueden ser empleados en la fabricación de placas de yeso laminado en cumplimiento con la normativa

Aportaciones a la síntesis de tres análogos del ácido nitrilotriacético derivados de alaninas

Se aislan y estudian los factores relativos a la preparación de los ácidos D, L-α-alanin -N,N -bis (carboximetil), 2-metil-α-alanin-N,N-bis (carboximetil) y β-alanin-N,N-bis(carboximetil) por condensación de cloro acetato con la correspondiente alanina, en medio alcalino. Los rendimientos, comparables con los anteriormente publicados, se explican en base a dificultades en la condensación y a diferencias observadas en la solubilidad de estos productos. Asimismo, se aporta por primera vez la síntesis de sus clorhidratos y se incluyen diversos datos para la caracterización de los ácidos.In this work we have studied and discussed the factors related to the preparation of the acids D, L-alanine-N N-bis(carboxymethyl), 2-methyl-aalanine-N,N-bisC'carboxymethyl) y B-alanine-N,N-bisCcarboxymethyl) through condensation of chloroacetate with the corresponding alanine in alkaline medium. Similar yields as published earlier, are discussed and explained on the basis of difficulties in the condensation process and observed differencies in the solubility of these products. By first time, the isolation of their hydrochlorides is provided and several data for the chara,cterization of the acids are included

Contribución al estudio de la hidrolisis de quelatos 1:1 de ácidos aminotricarboxílicos con iones trivalentes lantánidos

La hidrólisis alcalina de disoluciones equimolares de los ácidos (H3A) nitrilotriacético (ANT), D, L-a-alanina-N, N-bis (carboximetil) (AiMNT), 2-metil a-alanina-N, N-bis (carboximetil) (ADNT) o alanin-N, N-bis (carboximetil) con un nitrato trivalente lantánido o de itrio [1 = 0,1 mol X dm-3 (KN03)] se pone de manifiesto en las curvas de valoración potenciométrica frente a KOH 0,1 mol X dm-3, a 25° C y atmósfera de N2• La hidrólisis representa el consumo de entre 1 y 1,5 equivalentes de base/ion-gramo de lantánido, en desacuerdo con lo descrito en la bibliografía para el 'caso del ANT. Este comportamiento se explica por la contribución de diversos procesos asociados a la hidrólisis de los quelatos 1: 1 [Ln A(HP)x] a hidroxocomplejos con OH/Ln>1. La tendencia a la hidrólisis crece al avanzar en la serie lantánida , con cierta irreguaridad, lo que se explica por la influencia de las 'características cristalquímicas de los iones y por la posible disminución en una unidad del número de moléculas de agua coordinadas en quelatos 1: 1 de los elementos centrales de la serie.The alkaline hydrolysis of eqimolar solutions of (H3A) nitrilotriacetic acid (NTA), N, N-bis (carboxymethyl)-D, L-a-alanine (MNTA). N, N-bis (carboxymethyl)-2-methyl-a-alanine (DNTA) or N, N-bis (carboxymethyl)--alanine (NPDA) with a nitrate of trivalent lanthanide or yttrium ions [1 = 0.1 mol X dm-3 (KNOa )] is shown by potentiometric titration curves against KOH 0,1 mol X X dm a at 25° e, under N2 atmosfere. From 1 to 1.5 equivalents of base/ lanthanide g-ion were consummed in the hydrolysis, in disagreement with previous data reported for the NTA case. This behavoir is explained the contribution of several processes associated to the hydrolysis of the 1: 1: che late [LnA(Hp)x], to give hydroxo-complexes with OH/Ln > 1. Tendency towards hydrolysis increase with certain irregularities throught the lanthanide series; this fact is explained on the basis of the influence of the crystallochemicaI characteristics of the lanthanicte ions and also by the possible decrease of one unit in the number of coordinated wated molecules in the 1: 1 chelates of the central elements of the series