Tuning the Covering on Gold Surfaces by Grafting Amino-Aryl Films Functionalized with Fe(II) Phthalocyanine: Performance on the Electrocatalysis of Oxygen Reduction.

Current selective modification methods, coupled with functionalization through organic or inorganic molecules, are crucial for designing and constructing custom-made molecular materials that act as electroactive interfaces. A versatile method for derivatizing surfaces is through an aryl diazonium salt reduction reaction (DSRR). A prominent feature of this strategy is that it can be carried out on various materials. Using the DSRR, we modified gold surface electrodes with 4-aminebenzene from 4-nitrobenzenediazonium tetrafluoroborate (NBTF), regulating the deposited mass of the aryl film to achieve covering control on the electrode surface. We got different degrees of covering: monolayer, intermediate, and multilayer. Afterwards, the ArNO2 end groups were electrochemically reduced to ArNH2 and functionalized with Fe(II)-Phthalocyanine to study the catalytic performance for the oxygen reduction reaction (ORR). The thickness of the electrode covering determines its response in front of ORR. Interestingly, the experimental results showed that an intermediate covering film presents a better electrocatalytic response for ORR, driving the reaction by a four-electron pathway.

Dopamine and Caffeine Encapsulation within Boron Nitride (14,0) Nanotubes: Classical Molecular Dynamics and First Principles Calculations.

Classical molecular dynamics (MD) and density functional theory (DFT) calculations are developed to investigate the dopamine and caffeine encapsulation within boron nitride (BN) nanotubes (NT) with (14,0) chirality. Classical MD studies are done at canonical and isobaric-isothermal conditions at 298 K and 1 bar in explicit water. Results reveal that both molecules are attracted by the nanotube; however, only dopamine is able to enter the nanotube, whereas caffeine moves in its vicinity, suggesting that both species can be transported: the first by encapsulation and the second by drag. Findings are analyzed using the dielectric behavior, pair correlation functions, diffusion of the species, and energy contributions. The DFT calculations are performed according to the BLYP approach and applying the atomic base of the divided valence 6-31g(d) orbitals. The geometry optimization uses the minimum-energy criterion, accounting for the total charge neutrality and multiplicity of 1. Adsorption energies in the dopamine encapsulation indicate physisorption, which induces the highly occupied molecular orbital-lower unoccupied molecular orbital gap reduction yielding a semiconductor behavior. The charge redistribution polarizes the BNNT/dopamine and BNNT/caffeine structures. The work function decrease and the chemical potential values suggest the proper transport properties in these systems, which may allow their use in nanobiomedicine.

Efficacy and safety of two whole IgG polyvalent antivenoms, refined by caprylic acid fractionation with or without beta-propiolactone, in the treatment of Bothrops asper bites in Colombia.

The efficacy and safety of two whole IgG polyvalent antivenoms (A and B) were compared in a randomised, blinded clinical trial in 67 patients systemically envenomed by Bothrops asper in Colombia. Both antivenoms were fractionated by caprylic acid precipitation and had similar neutralising potencies, protein concentrations and aggregate contents. Antivenom B was additionally treated with beta-propiolactone to lower its anticomplementary activity. Analysing all treatment regimens together, there were no significant differences between the two antivenoms (A=34 patients; B=33 patients) in the time taken to reverse venom-induced bleeding and coagulopathy, to restore physiological fibrinogen concentrations and to clear serum venom antigenaemia. Blood coagulability was restored within 6-24 h in 97% of patients, all of whom had normal coagulation and plasma fibrinogen levels 48 h after the start of antivenom treatment. Two patients (3.0%) had recurrent coagulopathy and eight patients suffered recurrence of antigenaemia within 72 h of treatment. None of the dosage regimens of either antivenom used guaranteed resolution of venom-induced coagulopathy within 6 h, nor did they prevent recurrences. A further dose of antivenom at 6 h also did not guarantee resolution of coagulopathy within 12-24 h in all patients. The incidence of early adverse reactions (all mild) was similar for both antivenoms (15% and 24%; P>0.05).

Shoot demography in new England populations of Maianthemum canadense desf.

The demography of shoots of eight populations of a herbaceous perennial exhibiting clonal growth, is presented. The study was done along an elevational gradient, from a more open secondary mixed forest to a denser, more mature stand. Most shoots lived one to three years on the average, but shoots as old as twelve years were found. Large variation in formation and mortality of shoots was observed among plots and years. Yearly trends in the mortality rates of site replicates showed a higher correlation than rates of shoot formation. Although the density of shoots was highest in the drier sites, the turnover of shoots was highly variable and apparently uncorrelated with site location. Age structures revealed a tendency of longer-lived and higher reproductive activities among shoots from more mesic sites. It is hypothesized that environmental rather than density controls are primary causes of the population dynamics observed in this species.

[Tityus asthenes scorpion stings: epidemiological, clinical and toxicological aspects]. / Picaduras por escorpión Tityus asthenes en Mutatá, Colombia: aspectos epidemiológicos, clínicos y toxinológicos.

INTRODUCTION: Scorpion stings are a public health problem in many countries. However, in Colombia, very few epidemiological, clinical or toxicological studies have been undertaken. OBJECTIVE: Ecological and epidemiological aspects were related to the prevalence of scorpion stings by Tityus asthenes. The clinical features of envenomization were described in patients and in an experimental animal model. MATERIALS AND METHODS: The study was conducted in four localities of Mutatá and Urabá Counties in the province of Antioquia, Colombia. The sample consisted of 1,593 (929 urban, 664 rural) of the 5,305 exposed people, inhabitating 324 households (188 urban (58%); 136 rural (42%) of 1,448 houses total in the study area. An interview survey was performed in every selected family for a more realistic estimate of sting prevalence. Additionally, a prospective study was directed toward patients presenting scorpion stings at care at the local hospital over an 18-month period. RESULTS: The probability was 12.9 times greater of finding T. asthenes inside or around houses in places near to forest and high agrarian plantations (odds ratio = 13). Eighty scorpion stings were reported in the retrospective study (4.1% prevalence [95% CI 3.3-4.8%] ), but only 14 of the patients (17.5%) sought care in the local hospital (an 82.5% underreportage). Seventy percent of the stings occurred in rural places; 50% occurred in the locality of Caucheras, with an attack rate of 10.6%. The overall household infestation rate was 269% (95% CI 22.9-30.8%) and an area dispersion ratio of 100%. Signs of systemic envenomization occurred mainly in children (67%). The 50% lethal dose of T. asthenes venom was 121.6 µg for 18-20 g Swiss Webster rats (95% CI 103.7-139.6). Immunodetection of T. asthenes and Centruroides gracilis/C.margantatus venoms in the experimental animals was possible when were tested by Western blot against Alacramyn (Instituto Bioclón, México) and Soro antiaracnídico (Instituto Butantan, Brasil) antivenoms. Scorpion interspecific differences were noted. CONCLUSIONS: The prevalence of stings by T. asthenes were common and their presence was associated with tropical rainforests. Envenomization at low density can be neutralized efficiently by anti-scorpion antivenoms produced in México and Brazil but with differing specificities for the venom of each scorpion species.

Picaduras por escorpión Tityus asthenes en Mutatá, Colombia: aspectos epidemiológicos, clínicos y toxinológicos / Tityus asthenes scorpion stings: epidemiological, clinical and toxicological aspects

Introducción. El escorpionismo afecta a países tropicales como Colombia.Objetivo. Determinar los indicadores ecológicos y epidemiológicos de las picaduras por Tityus asthenes en cuatro localidades de Mutatá, Colombia, y las características clínicas del envenenamiento y toxinológicas del veneno. Materiales y métodos. Es un estudio prospectivo/retrospectivo descriptivo y experimental; se visitaron aleatoriamente 324 de las 1.448 viviendas del municipio: 188 urbanas (58,0%) y 136 rurales (42,0%), con 1.593 habitantes. En 18 meses se estudiaron prospectivamente los pacientes picados por T. asthenes que ingresaron al hospital local y, retrospectivamente en encuestas domiciliarias, se determinó el subregistro. Se recolectaron escorpiones vivos y se realizaron experimentos con el veneno. Resultados. Hubo 12,9 más probabilidades de hallar ejemplares de T. asthenes en el área rural (OR=6,5; IC95% 3,9-10,8), en el intradomicilio y peridomicilio cercano a bosques y plantaciones agrarias altas (OR=13,0; IC95% 7,5-23,0). Se reportaron 80 picaduras ocurridas en los dos últimos años (prevalencia de 4,1%; IC95% 4,8-3,3); sólo 14 personas (17,5%) consultaron al hospital (subregistro de 82,5%). La prevalencia ponderada de infestación por escorpiones en las viviendas encuestadas fue de 26,9% (112 casas) (IC95% 30,8-22,9). El 50% de los accidentes ocurrió en la localidad de Caucheras: 10,6% de proporción de ataque. El envenenamiento sistémico fue más frecuente en niños (67%). La dosis letal 50 del veneno en ratones de 18 a 20 g, fue 121,6 μg (IC95% 103,7-139,6). Hubo reactividad inmunológica por Western blot de los antivenenos del Instituto Bioclón, México (Alacramyn®) y del Instituto Butantan, Brasil (Soro antiaracnídico®)...

Introduction. Scorpion stings are a public health problem in many countries. However, in Colombia, very few epidemiological, clinical or toxicological studies have been undertaken. Objective. Ecological and epidemiological aspects were related to the prevalence of scorpion stings by Tityus asthenes. The clinical features of envenomization were described in patients and in an experimental animal model. Materials and methods. The study was conducted in four localities of Mutatá and Urabá Counties in the province of Antioquia, Colombia. The sample consisted of 1,593 (929 urban, 664 rural) of the 5,305 exposed people, inhabitating 324 households (188 urban (58%); 136 rural (42%) of 1,448 houses total in the study area. An interview survey was performed in every selected family for a more realistic estimate of sting prevalence. Additionally, a prospective study was directed toward patients presenting scorpion stings at care at the local hospital over an 18-month period. Results. The probability was 12.9 times greater of finding T. asthenes inside or around houses in places near to forest and high agrarian plantations (odds ratio=13). Eighty scorpion stings were reported in the retrospective study (4.1% prevalence [95% CI 3.3-4.8%] ), but only 14 of the patients (17.5%) sought care in the local hospital (an 82.5% underreportage). Seventy percent of the stings occurred in rural places; 50% occurred in the locality of Caucheras, with an attack rate of 10.6%. The overall household infestation rate was 269% (95% CI 22.9-30.8%) and an area dispersion ratio of 100%. Signs of systemic envenomization occurred mainly in children (67%). The 50% lethal dose of T. asthenes venom was 121.6 μg for 18-20 g Swiss Webster rats (95% CI 103.7-139.6). Immunodetection of T. asthenes and Centruroides gracilis/C.margantatus venoms in the experimental animals was possible when were tested by Western blot against Alacramyn® (Instituto Bioclón, México) and Soro antiaracnídico®...