A terminal Fe
III
OH complex, Fe
III
(L)(OH)
2−
(
1
), has been synthesized and structurally characterized (H
4
L = 1,2-bis(2-hydroxy-2-methylpropanamido)benzene). The oxidation reaction of
1
with ...one equiv. of
tris
(4-bromophenyl)ammoniumyl hexachloroantimonate (TBAH) or ceric ammonium nitrate (CAN) in acetonitrile at −45 °C results in the formation of a Fe
III
OH ligand radical complex, Fe
III
(L&z.rad;)(OH)
−
(
2
), which is hereby characterized by UV-visible,
1
H nuclear magnetic resonance, electron paramagnetic resonance, and X-ray absorption spectroscopy techniques. The reaction of
2
with a triphenylcarbon radical further gives triphenylmethanol and mimics the so-called oxygen rebound step of Cpd II of cytochrome P450. Furthermore, the reaction of
2
was explored with different 4-substituted-2,6-di-
tert
-butylphenols. Based on kinetic analysis, a hydrogen atom transfer (HAT) mechanism has been established. A p
K
a
value of 19.3 and a BDFE value of 78.2 kcal/mol have been estimated for complex
2
.
One-electron oxidation of an Fe
III
-OH complex (
1
) results in the formation of a Fe
III
-OH ligand radical complex (
2
). Its reaction with (C
6
H
5
)
3
C&z.rad; results in the formation of (C
6
H
5
)
3
COH, which is a functional mimic of compound II of cytochrome P450.
Time-resolved X-ray (tr-XAS) and optical transient absorption (OTA) spectroscopy in the picosecond time scale coupled with Density Functional theory (DFT) and X-ray absorption near-edge structure ...(XANES) calculations are applied to study three homoleptic Cu(
i
) dimeric chromophores with ethyl and longer propyl spacers, denoted as Cu
2
(mphenet)
2
Cl
2
(
C1
), Cu
2
(mphenet)
2
(ClO
4
)
2
(
C2
) and Cu
2
(mphenpr)
2
(ClO
4
)
2
(
C3
) (where mphenet = 1,2-bis(9-methyl-1,10-phenanthrolin-2-yl)ethane and mphenpr = 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane). Tr-XAS analysis after light illumination at ∼ 100 ps illustrate the formation of a flattened triplet excited state in all 3 complexes. Optical transient absorption (OTA) analysis for
C1
monitored in water and
C2
and
C3
measured in acetonitrile reveals distinct excited-state lifetimes of 169 ps, 670 ps and 1600 ps respectively. These differences are associated to changes in the solvent (comparing
C1
and
C2
) and the flexibility of the ligand to adapt after Cu flattening upon excitation (
C2
and
C3
). Our results are important for the improved structural dynamics of these types of Cu-based dimeric compounds, and can guide the integration of these chromophores into more complex solar energy conversion schemes.
Three homoleptic Cu(
i
) dimeric photosensitizers are studied through ultrafast X-ray and optical absorption spectroscopy. The complexes show distinct excited state lifetimes, due to the solvent type and spacers' flexibilities between the Cu centres.
A new Ru oligomer of formula {RuII(bda-κ-N2O2)(4,4′-bpy)10(4,4′-bpy)}, 10 (bda is 2,2′-bipyridine-6,6′-dicarboxylate and 4,4′-bpy is 4,4′-bipyridine), was synthesized and thoroughly characterized ...with spectroscopic, X-ray, and electrochemical techniques. This oligomer exhibits strong affinity for graphitic materials through CH−π interactions and thus easily anchors on multiwalled carbon nanotubes (CNT), generating the molecular hybrid material 10@CNT. The latter acts as a water oxidation catalyst and converts to a new species, 10′(H 2 O) 2 @CNT, during the electrochemical oxygen evolution process involving solvation and ligand reorganization facilitated by the interactions of molecular Ru catalyst and the surface. This heterogeneous system has been shown to be a powerful and robust molecular hybrid anode for electrocatalytic water oxidation into molecular oxygen, achieving current densities in the range of 200 mA/cm2 at pH 7 under an applied potential of 1.45 V vs NHE. The remarkable long-term stability of this hybrid material during turnover is rationalized based on the supramolecular interaction of the catalyst with the graphitic surface.
Introduction. In the last decades, there has been an increased on the interest of Tabasco Chilli pepper cultivation in Colombia; however, production limitation has been observed due to phytosanitary ...problems. Species of the genus Fusarium cause root and stem rots with large losses for farmers; whereby, it is important to find alternatives to vascular wilt managment caused by Fusarium spp. Objective. The objective of this research was to isolate and characterize endophytic foliar bacteria with in vitro antagonistic potential against Fusarium spp. in Tabasco Chili pepper (Capsicum frutescens) plants. Materials and methods. In the period between February 2014 and February 2016, the in vitro antagonistic capacity of 68 bacterial endophytes of leaf tissue C. frutescens, from two municipalities of Valle del Cauca, Colombia, was evaluated. The isolated bacteria were confronted with six pathogenic isolates of Fusarium spp. by dual growth method. Results. Fifty of the bacterial isolates showed percentages of inhibition against at least one Fusarium isolate, and of these sixteen had percentages of inhibition above 40 %. The morphology, biochemical profile and molecular characterization allowed to determine that the isolates identified as Bacillus subtillis and Pseudomonas aeruginosa showed inhibition averages between 62 and 89%, high averages compared to those previously reported in other studies. In addition, stand out as new findings of bacteria associated with endophytic plant tissue of C. frutescens, in Valle del Cauca, Colombia, the Enterobacter cloacae, Microbacterium arborescens, and Stenotrophomonas maltophilia species. Conclusion. These results constitute a potential source for pathogen management and productivity improvement in tabasco chili pepper in Colombia.
Introducción. En las últimas décadas se ha incrementado el interés por el cultivo de ají tabasco en Colombia, sin embargo, se han observado limitantes en la producción, debido a problemas fitosanitarios. Especies del género Fusarium ocasionan pudriciones de raíz y tallo con pérdidas cuantiosas para los agricultores, por lo cual es importante encontrar alternativas de manejo a la marchitez vascular ocasionada por Fusarium spp. Objetivo. El objetivo de este trabajo fue aislar y caracterizar bacterias endófitas, con potencial antagónico in vitro frente a Fusarium spp., en plantas de ají tabasco (Capsicum frutescens var. Tabasco). Materiales y métodos. En el periodo entre febrero de 2014 a febrero de 2016, se evaluó la capacidad antagónica in vitro de 68 aislados bacterianos endófitos de tejido foliar C. frutescens, provenientes de dos municipios del Valle del Cauca, Colombia. Las bacterias aisladas fueron enfrentadas a seis aislamientos patogénicos de Fusarium spp, mediante el método de crecimiento dual. Resultados. Cincuenta de los aislados bacterianos presentaron porcentajes de inhibición frente al menos un aislado de Fusarium y de estos, dieciséis presentaron porcentajes de inhibición por encima del 40 %. La morfología, perfil bioquímico y caracterización molecular, permitieron determinar que los aislados identificados como Bacillus subtillis y Pseudomonas aeruginosa, mostraron promedios de inhibición entre 62 y 89 %, altos con respecto a los reportados anteriormente en otros estudios. Además, se destacan como nuevos hallazgos de bacterias asociadas al tejido vegetal endófito de C. frutescens, en el Valle del Cauca, Colombia, a las especies Enterobacter cloacae, Microbacterium arborescens, y Stenotrophomonas maltophilia. Conclusión. Estos resultados constituyen una fuente potencial para el manejo de patógenos y mejoramiento de la productividad en el ají tabasco en Colombia.
Herein, we show that the reaction of a mononuclear FeIII(OH) complex (1) with N-tosyliminobenzyliodinane (PhINTs) resulted in the formation of a FeIV(OH) species (3). The obtained complex 3 was ...characterized by an array of spectroscopic techniques and represented a rare example of a synthetic FeIV(OH) complex. The reaction of 1 with the one-electron oxidizing agent was reported to form a ligand-oxidized FeIII(OH) complex (2). 3 revealed a one-electron reduction potential of −0.22 V vs Fc+/Fc at −15 °C, which was 150 mV anodically shifted than 2 (E red = −0.37 V vs Fc+/Fc at −15 °C), inferring 3 to be more oxidizing than 2. 3 reacted spontaneously with (4-OMe-C6H4)3C• to form (4-OMe-C6H4)3C(OH) through rebound of the OH group and displayed significantly faster reactivity than 2. Further, activation of the hydrocarbon C–H and the phenolic O–H bond by 2 and 3 was compared and showed that 3 is a stronger oxidant than 2. A detailed kinetic study established the occurrence of a concerted proton–electron transfer/hydrogen atom transfer reaction of 3. Studying one-electron reduction of 2 and 3 using decamethylferrocene (Fc*) revealed a higher k et of 3 than 2. The study established that the primary coordination sphere around Fe and the redox state of the metal center is very crucial in controlling the reactivity of high-valent Fe–OH complexes. Further, a FeIII(OMe) complex (4) was synthesized and thoroughly characterized, including X-ray structure determination. The reaction of 4 with PhINTs resulted in the formation of a FeIV(OMe) species (5), revealing the presence of two FeIV species with isomer shifts of −0.11 mm/s and = 0.17 mm/s in the Mössbauer spectrum and showed FeIV/FeIII potential at −0.36 V vs Fc+/Fc couple in acetonitrile at −15 °C. The reactivity studies of 5 were investigated and compared with the FeIV(OH) complex (3).
Abstract Total anomalous pulmonary venous return (TAPVR), also known as total anomalous pulmonary venous connection, is a congenital cardiovascular malformation that presents itself in the neonatal ...period, with cyanosis and tachypnea. There are 4 types of TAPVR with the mixed type being the least common. Any type of TAPVR may be associated with obstruction as result of flow redirection through the liver parenchyma before it may return to the heart, but infracardiac is the most common one. We report a case of a 10-hour-old female, with a mixed (cardiac and infracardiac) TAVPR with obstruction, that showed drainage to the coronary sinus and the portal vein, as the other classic findings in TAVPR, made with computed tomography angiography and echocardiogram. The patient was taken to surgical repair, but unfortunately died during the procedure because of multiple complications.
Objetivo. Caracterizar la avifauna presente en la granja agroecológica Ekonukos de la Corporación Universitaria Minuto de Dios, como fuente de información para la descripción y desarrollo de futuros ...modelos de aviturismo, educación ambiental y acciones de conservación en el área de estudio. Materiales y métodos. Se definieron cuatro zonas de acuerdo con su cobertura vegetal o uso del suelo (Zona de edificaciones o habitable-ZE, Bosque secundario BS, Zona de cultivos ZC y Pastizales o zona abierta-Pza). En cada zona se estableció un punto de observación con radio fijo, se realizaron observaciones y se practicaron recorridos mediante transectos lineales. Las especies registradas fueron identificadas y categorizadas por tipo de hábitat (ZE, BS, ZC o Pza), alimentación, frecuencia de registros y estado de amenaza o conservación. Resultados. Se encontraron 84 especies de aves, distribuidas en 18 órdenes, 34 familias y 74 géneros. El orden Passeriformes presentó la mayor riqueza de especies al igual que las familias Tyrannidae y Thraupidae. Del total de especies, 79 corresponden a poblaciones residentes, cuatro a migratorias boreales y una migratoria austral. A demás, la especie Amazona farinosa está en estado de amenaza, en la categoría NT o casi amenazada. Conclusiones. Las especies encontradas constituyen un aporte importante para el conocimiento de la avifauna local e invita a realizar acciones de restauración y manejo de la flora del sitio de estudio, con el fin de generar una mejor conectividad con las áreas cercanas y oferta alimenticia para las especies encontradas.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The passion fruit’s production in Colombia has shown great advances; however, phytosanitary diseases remain as issues in passion fruit production. This includes the pathogens that hinder the ...establishment and development of the crop, such as some species of the genus Fusarium, pathogen considered as an important one because of the economic losses that it generates. The objective of this work was to molecularly identificate the populations of Fusarium associated with passion fruit (Passiflora edulis). Between January and December 2015, an isolation of 35 samples based on different affected organs of the plant and from localities found in five municipalities was performed in Valle del Cauca, Colombia. Eight isolates were selected and purified in order to perform their DNA’s extraction and also an amplification of region TEF 1 alpha. The PCR products were sequenced and compared with the NCBI database and Fusarium ID. The results obtained by sequencing showed that the isolates belong to Fusarium incarnatum, Fusarium
solani, and Fusarium proliferatum, the first species had a mayor occurrence in the tested samples. The analysis of phylogenetic relationships was achieved by using the 6 MEGA program, and by using the similarity coefficient nearest neighbor, which allowed to observe the variability among the evaluated isolates.
La producción de maracuyá en Colombia ha mostrado grandes avances; sin embargo, las enfermedades continúan siendo un factor limitante en la producción del mismo. Entre los agentes patógenos que dificultan el establecimiento y desarrollo del cultivo, se encuentran algunas especies del género Fusarium, consideradas de importancia económica por las pérdidas que generan. El objetivo de este trabajo fue identificar molecularmente las poblaciones de Fusarium presentes en maracuyá (Passiflora edulis). Entre enero y diciembre de 2015 se realizó el aislamiento de 35 muestras de diferentes órganos afectados de la planta y provenientes de localidades ubicadas en cinco municipios del Valle del Cauca, Colombia. Se seleccionaron y purificaron ocho aislamientos pertenecientes al género de interés para realizar la extracción de ADN y amplificación de la región TEF 1 alpha. Los productos de PCR fueron secuenciados y comparados con las bases de datos del NCBI y del Fusarium ID. Los aislamientos pertenecían a: Fusarium incarnatum, Fusarium proliferatum y Fusarium solani, la primera especie fue la de mayor ocurrencia en las muestras evaluadas. En el análisis de las relaciones filogenéticas realizado mediante el programa MEGA 6, se usó el coeficiente de similitud del vecino más cercano, lo que permitió observar variabilidad entre los aislamientos evaluados.
A Cu II complex (1) of a bis-pyridine-dioxime ligand and its one-electron oxidized analog (1-ox) were thoroughly characterized by various spectroscopic techniques, including X-ray absorption ...spectroscopy. 1-ox was found to be a Cu II complex of a ligand iminoxyl radical and represents the first example of such a type. Reorganization energy ( λ ) of 2.12 eV was determined for the 1-ox/1 couple, which is considerably higher than the type 1 protein and synthetic Cu III/II (OH) complexes.
PDF
