Enantioselective Synthesis of Succinimides by Michael Addition of Aldehydes to Maleimides Organocatalyzed by Chiral Primary Amine-Guanidines

The monoguanylation of (1S,2S)- and (1R,2R)-cyclohexane-1,2-diamine affords chiral primary amine-guanidines that are used as chiral organocatalysts in the enantioselective Michael addition of aldehydes, particularly α,α-disubstituted aldehydes, to maleimides. The reaction is carried out in the presence of imidazole, as an additive, in aqueous N,N-dimethylformamide, as the solvent, and affords the corresponding enantioenriched succinimides in high or quantitative yields with enantioselectivities up to 96 % ee. Theoretical calculations (DFT and M06–2X) suggest a different hydrogen-bonding coordination pattern between the maleimide (C=O) and the catalyst (NH groups) is responsible for the enantioinduction switch that is observed when the reaction is carried out using primary amine-guanidines versus primary amine-thioureas as the organocatalysts.The authors thank the Spanish Ministerio de Economía y Competitividad (MEC) (projects CTQ2010-20387, CTQ2010-21263-C02, and Consolider Ingenio 2010, CSD2007-00006), the Fondos Europeos para el Desarrollo Regional (FEDER), the COST Action CM0905 “Organocatalysis”, the Generalitat Valenciana (Prometeo/2009/039), the Basque Government (GV grant IT-291-07), the University of Alicante, and the University of the Basque Country for the financial support

Enantioselective Michael addition of isobutyraldehyde to nitroalkenes organocatalyzed by chiral primary amine-guanidines

Primary amine-guanidines derived from trans-cyclohexane-1,2-diamines are used as organocatalysts for the enantioselective conjugate addition of isobutyraldehyde to arylated and heteroarylated nitroalkenes. The reaction was performed in the presence of imidazole as the additive in aqueous DMF as the solvent at 0 °C. The corresponding Michael adducts bearing a new stereocenter were obtained in high yields and with enantioselectivities of up to 80%. Theoretical calculations are used to justify the observed sense of the stereoinduction.Spanish Ministerio de Economía y Competitividad (projects CTQ2010-20387, CTQ2010-21263-C02 and Consolider Ingenio 2010, CSD2007-00006), FEDER, the COST Action CM0905 ‘Organocatalysis’, the Generalitat Valenciana (Prometeo/2009/039), the Basque Government (GV Grant IT-291-07), the FP7 Marie Curie Actions of the European Commission via the ITN ECHONET Network (MCITN-2012-316379) and the universities of Alicante and the Basque Country

Jaguar (Panthera onca) and puma (Puma concolor) diets in Quintana Roo, Mexico

A study was carried out for two years in Northwest Quintana Roo, México, using scat analysis to determine the diet and prey preferences of pumas and jaguars. Cat species and gender were determined using molecular techniques (rapid classificatory protocol: polymerise chain reaction, RCP–PCR), and prey abundance was estimated from camera trapping. The scats contained remains from 16 wild mammal species, but there was no evidence of livestock or other taxa. The diet breadths of jaguar (0.32) and puma (0.29) indicated a high degree of prey specialization, which combined with their dietary overlap (Pianka index 0.77) suggested competition between them. However, both felids showed a preference for red brocket deer Mazama temama, and frequently consumed collared peccaries Pecari tajacu. The importance of such large ungulates in the felids' diets is similar to the expected patterns of wild meat consumption in rural areas of the Northern Yucatan Peninsula. Therefore, future conservation management plan initiatives should involve local rural communities in the management of sustainable hunting, considering these ungulates are also the felid prey species. Resumen La dieta del jaguar (Panthera onca) y del puma (Puma concolor) en Quintana Roo, en México. El estudio se realizó durante dos años en el noroeste de Quintana Roo, en México y se utilizó el análisis de excrementos para determinar la dieta y las preferencias de presas del puma y del jaguar. Se utilizaron técnicas moleculares para identificar la especie de félido y el sexo (protocolo de clasificación rápida: reacción en cadena de la polimerasa, RCP–PCR), y se estimó la abundancia de presas mediante el método de trampeo fotográfico. Los excrementos contenían restos de 16 especies de mamíferos salvajes, pero no se encontraron restos de ganado ni de otros taxones. La amplitud de la dieta del jaguar (0,32) y del puma (0,29) indica que son especies con un alto grado de especialización, lo cual, junto con el traslape de las dietas (índice de Pianka = 0,77) sugiere que ambos félidos compiten entre sí. Asimismo, ambos mostraron preferencia por el venado temazate, Mazama temama, y frecuentemente consumieron pecarí de collar, Pecari tajacu. La importancia de la presencia de este tipo de ungulados en la dieta de los félidos se corresponde con la pauta esperada de consumo de carne de caza en las zonas rurales del norte de la península de Yucatán. Por lo tanto, las futuras iniciativas encaminadas a planificar la conservación de ambos félidos deberían hacer partícipes a las comunidades rurales en la gestión de la cacería sustentable, considerando que estos ungulados también son presas de los félidos

Coexistence of jaguars (Panthera onca) and pumas (Puma concolor) in a tropical forest in south–eastern Mexico

The biological ranges of the jaguar (Panthera onca) and puma (Puma concolor) overlap in the Yucatan Peninsula, corresponding to the most important population of jaguars in Mexico. The goal of this study in the El Eden Ecological Reserve (EER) was to investigate the factors that permit these two predators to coexist in the dense vegetation of medium–stature tropical forest and secondary forest in the north–eastern Yucatan Peninsula. We assessed their spatial and temporal overlap using Pianka’s index, and evaluated their habitat use by applying occupancy models. A total sampling effort of 7,159 trap–nights over 4 years produced 142 independent photographic records of jaguars, and 134 of pumas. The felids showed high to very high overlap in their use of different vegetation (0.68–0.99) and trail types (0.63–0.97) and in their activity patterns (0.81–0.90). However, their peak activity patterns showed some temporal separation. Time of day, particularly for peak activity time, was the best predictor to explain the coexistence of the felids in this habitat. While occupancy models showed that the presence of potential prey species and vegetation type could predict the presence of felids in the study area. Natural disturbances during 2010 (hurricane) and 2011 (fire) drastically changed habitat use and activity patterns, resulting in pumas and jaguars adjusting their resource–use and activity pattern through a strategy of mutual evasion

An Evaluation of the Contemporary Uses and Cultural Significance of Mammals in Mexico

We evaluated current uses of wild mammals by indigenous and mestizo communities in Mexico by extracting data from 59 sources published or produced between 1987–2017, covering data from 240 localities and 3,905 questionnaires. We then calculated a Cultural Value Index (CVI) previously applied to plants to quantify resource use and assess the cultural significance of each mammal. A total of 82 species were reported, and the animals with the highest cultural importance according to their CVI (in brackets) were two species of deer (Odocoileus virginianus [18.32] and Mazama temama [10.04]), as well as the nine-banded armadillo (Dasypus novemcinctus [14.18]), white-nosed coati (Nasua narica [14.75]), collared peccary (Pecari tajaccu [11.90]), northern raccoon (Procyon lotor [11.28]) and spotted paca (Cuniculus paca [9.84]). The most common uses were for food, to reduce the damage or harm they cause, and for medicinal purposes, with O. virginianus, P. lotor, N. narica, and D. novemcinctus frequently hunted for all these reasons. Our analysis also highlighted the hunting of rarer species of national conservation concern, including commercial trading of body parts of the felids Panthera onca, Leopardus pardalis, and Leopardus wiedii. By quantifying the ethnozoological significance of wildlife to indigenous communities, indices such as CVI provide a robust measure of the extent of use and preference for particular species or taxa. This adds to the body of evidence used to develop effective regulations and laws related to harvesting and hunting, and helps promote a more sustainable and long-term approach to the use of natural resources

Uso y valor cultural de la herpetofauna en México: una revisión de las últimas dos décadas (1997–2017)

Amphibians and reptiles are vertebrate groups that historically have been used by rural communities. In Mexico, the multiculturalism of the country is closely related to the biological diversity with which it coexists. The use of the Cultural Importance Index (IIC) allows quantify the value of species with different uses and can be useful to focus conservation strategies. The objective of the study was to identify the use and generate an IIC of the herpetofauna, through a bibliometric meta-analysis of publications on the use of Mexican amphibians and reptiles. There were 103 reptiles and 32 amphibians that have at least one use, which varied depending on the taxon (reptiles or amphibians, respectively): food (47, 10), pet (20, 6), commercial (20, 2), ornamental (25, 1), artisan (32, 9), magic-religious (32, 10), medicinal (57, 19), sport hunting (2, 2), damage control (48, 2), beneficial (10, 4). Rhinella marina (27.13) and Crocodylus moreletii (15.42) were the species with the highest IIC. Of the species recorded, 61% and 31% of reptiles and amphibians respectively are in some risk category. It is necessary establish conservation strategies through management and education programs that promote sustainable uses of resources, as well as the conservation of natural spaces where these species inhabit.Anfibios y reptiles son grupos de vertebrados que históricamente ha sido utilizado por comunidades rurales. En México, la multiculturalidad del país está estrechamente relacionada con la diversidad biológica con la que coexiste. El uso del Índice de Importancia Cultural (IIC) permite cuantificar el valor de las especies con diversos usos y puede ser de utilidad para enfocar estrategias de conservación, tomando en cuenta el valor cultural de las especies. El objetivo del estudio fue identificar los usos y generar un IIC de la herpetofauna, mediante un meta-análisis bibliométrico de publicaciones sobre el uso de anfibios y reptiles mexicanos. Se registraron 103 reptiles y 32 anfibios que tienen al menos un uso, el cual varió dependiendo del taxón (reptiles o anfibios, respectivamente): alimenticio (47, 10), mascota (20, 6), comercial (20, 2), ornamental (25, 1), artesanal (32, 9), mágico-religioso (32, 10), medicinal (57, 19), caza deportiva (2, 2), control de daños (48, 2), benéfico (10, 4), otros (3, 3). Rhinella marina (27.13) y Crocodylus moreletii (15.42) fueron las especies con mayor IIC. De las especies registradas, el 61 % y 31 % de reptiles y anfibios, respectivamente, están en alguna categoría de riesgo. Es necesario establecer estrategias de conservación por medio de manejo y programas educativos que promuevan alternativas de uso sustentable de los recursos, así como la conservación de espacios naturales donde las especies habitan

A Quantitative Method for Evaluating Contemporary Cultural Uses of Birds – A case study from Mexico

This study evaluates the relationship between people and birds in Mexico, a country where high cultural and biological diversity are reflected in the close associations between people and natural resources, recorded since pre-Hispanic times. It systematically reviews 1041 records of cultural use of wild birds in Mexico published between 1996 – 2017, and analyzes patterns of contemporary use of avifauna. It classifies information for 252 birds by grouping uses of species and families into 11 categories and quantifies overall use with a Cultural Value Index (CVI). The data show that birds have a high cultural value as food, pets, and for medicinal uses (312, 235, and 119 records, respectively), particularly in the state of Chiapas. Large edible birds had the highest CVIs and included Plain chachalacas (Ortalis vetula; 9.72), Black-bellied whistling-ducks (Dendrocygna autumnali; 6.65), Crested guams (Penelope purpurascens; 6.25), and Great currasows (Crax rubra; 6.23), with the Cracidae family recorded as favored gamebirds. Conspicuous, brightly-colored birds had high CVIs, including Keel-billed toucans (Ramphastos sulfuratus; 6.50), Red-lored amazons, (Amazona autumnalis; 6.03), and allied species, which were traded or kept as pets despite legal protection. The high CVIs of Barn owls (Tyto alba; 5.45) were related to medicinal uses, and Mourning doves (Zenaida macroura; 5.69) were mainly used as gamebirds. Wild bird populations face increasing pressure from habitat loss and overexploitation. We propose that evaluating the ethnological significance of wildlife with indices like CVIs can quantify the distinctive needs of rural communities, which when combined with information on conservation status can develop more sustainable species management plan

The Physical Chemistry of Steel Deoxidation and Nozzle Clogging in Continuous Casting

Nozzle clogging in continuous casting of steel originates by the adherence of alumina particles and other oxides, precipitated during the liquid steel deoxidation, on the refractory material’s surface. Hence, these particles’ nucleation and growth rates in supersaturated melts are analyzed considering, specifically, the role of the interfacial tensions between alumina, silica, and other oxides and the liquid metal. Weak steel deoxidizers like silicon do not need high supersaturations favoring high nucleation rates, giving particles’ narrow size distributions thanks to fast diffusion and Ostwald-ripening coagulation. Strong deoxidizers, like aluminum, need high supersaturation levels leading to broad size distributions. Besides, the morphology of these particles depends on the nucleation and growth mechanisms. The adhesion forces among the deoxidation particles, forming clusters, depending on the morphology and the oxide’s chemistry. The stability of the nozzle’s clog, adhered to the nozzle’s wall, depends on the interface tensions between the melt and the nozzle’s refractory surface and between the melt and the inclusion. The results obtained here help set up basic recommendations in steel refining and materials specifications of casting nozzles

Aforismos militares y guerra del Arauco: las Memorias de los sucesos de la guerra de Chile de Jerónimo de Quiroga

In the present work we have tried to recover the military thought of the maestre de campo of the army of Chile, Jerónimo de Quiroga, author of Memorias de los sucesos de la guerra de Chile written at the end of the 17th century and that remained unpublished, where this one was analyzing not only the reasons of the prolongation of so bloody conflict, criticizing the political labor of many governors, but also it represents a good example of how certain ideas came out concerning the problematic of the war.En el presente trabajo hemos pretendido recuperar el pensamiento militar del maestre de campo del ejército de Chile, Jerónimo de Quiroga, autor de unas Memorias de los sucesos de la guerra de Chile escritas a finales del siglo XVII y que permanecieron inéditas, donde éste analizaba no sólo las causas de la prolongación de tan sangriento conflicto, criticando la labor política de muchos gobernadores, sino que también representa un buen ejemplo de cómo trascendieron ciertas ideas en torno a la problemática de la guerra