University of Costa Rica

About: University of Costa Rica is a education organization based out in San José, Costa Rica. It is known for research contribution in the topics: Population & Venom. The organization has 9817 authors who have published 16781 publications receiving 238208 citations. The organization is also known as: UCR & Universidad de Costa Rica.

Triply Bonded Nb24+ Tetragonal Lantern Compounds: Some Accompanied by Novel B−H···Na+ Interactions

Abstract: The diniobium tetragonal lantern compound Nb2(hpp)4, 1, has been prepared in high yields by the reaction of NbCl3(DME), DME = dimethoxyethane, with a mixture of lithium naphthalenide and Li(hpp), hpp = the anion of 1,3,4,6,7,8-hexahydropyrimido[1,2-a]pyrimidine. Compound 1 interacts with two equivalents of NaEt3BH to give the bis-adduct, 1·2NaEt3BH. In a refluxing mixture of THF/toluene, 1·2NaEt3BH loses one NaEt3BH molecule to give 1·NaEt3BH. Both adducts contain short Na to N−C−N “pseudo-allylic” interactions to the coordinated hpp ligand. Very little variation can be seen in the Nb−Nb bond distances, which are 2.2035(9), 2.2064(3), and 2.2187(7) A for 1, 1·2NaEt3BH and 1·NaEt3BH, respectively. By a synthetic route similar to that used to make 1, Nb2(azin)4·2LiCl·4THF, 2, was prepared using the anion of 7-azaindole; the Cl- ions are loosely coordinated to the Nb atoms. This ligand tends to give long metal−metal distances, and the Nb−Nb distance of 2.278(2) A is 0.07 A longer than that in 1.

Community richness of amphibian skin bacteria correlates with bioclimate at the global scale

Abstract: Animal-associated microbiomes are integral to host health, yet key biotic and abiotic factors that shape host-associated microbial communities at the global scale remain poorly understood. We investigated global patterns in amphibian skin bacterial communities, incorporating samples from 2,349 individuals representing 205 amphibian species across a broad biogeographic range. We analysed how biotic and abiotic factors correlate with skin microbial communities using multiple statistical approaches. Global amphibian skin bacterial richness was consistently correlated with temperature-associated factors. We found more diverse skin microbiomes in environments with colder winters and less stable thermal conditions compared with environments with warm winters and less annual temperature variation. We used bioinformatically predicted bacterial growth rates, dormancy genes and antibiotic synthesis genes, as well as inferred bacterial thermal growth optima to propose mechanistic hypotheses that may explain the observed patterns. We conclude that temporal and spatial characteristics of the host's macro-environment mediate microbial diversity.

Interest Rate Restrictions and Income Distribution

Abstract: Credit has been one of the most important components of the strategies for development in the agricultural sector of low income countries (LIC's). Not only is the input provided-money-fungible but an infrastructure, the banking system, is available for its supply, and it can be administered at a significant distance from the farm, unlike other inputs. Because credit programs are easier to implement than another type of program, there has been a rapid expansion of the volume of agricultural credit granted by formal lenders in LIC's.