4,344 research outputs found
Root nodule bacteria isolated from Lotus uliginosus for future use in phytostabilization of arsenic contaminated soils
Funding Information: This work was supported by the cooperation project between Portugal and Argentina: 'The genus Lotus and their utilization for the restoration of soils contaminated with heavy metals. The biochemistry and their symbionts', FCT/DREBM 00264, Proc. 4.1.3 and also by the European project: 'Raising the bio-based industrial feedstock capacity of marginal Lands (Margin Up)', nº101082089. Publisher Copyright: © 2023 by the author(s).In recent decades there has been growing concern around heavy metals and metalloid contamination in soil. Arsenic (As) is a ubiquitous trace metalloid. The high levels of this metalloid in soils are a consequence of human activities and also from natural inputs. In general, the biodiversity of microorganisms and plants decreases drastically in contaminated soils. The knowledge that some leguminous plants, mainly certain species of Lotus, are growing well in such soils has attracted our attention for studying symbioses that are well adapted to harsh conditions. In this work we studied the rhizobial population existing in the root nodules of native Lotus uliginosus Sch. growing in a central region of Portugal. This legume grows in soils particularly affected by As due the discharge of industrial liquid effluents from fertilizer and chemical facilities. Diversity and tolerance to different concentrations of As of root nodule bacteria were studied. Our results showed that the symbioses between L. uliginosus and As tolerant Bradyrhizobium isolates were efficient when a nutrient medium containing high As concentrations was used. The present work highlights the capacity of L. uliginosus to grow and establish nitrogen-fixing symbioses in soils strongly contaminated with As and its potential for future use to promote vegetation cover to stabilize As contaminated soils.publishersversionpublishe
Cambio de la estructura de la comunidad de colémbolos (Hexapoda: Collembola) en relación con el disturbio antrópico de los suelos
In order to evaluate the effects of the anthropic impact on the structure of de soil
collembolan community, three different soil uses were researched: agricultural fields (AG)
with 50 years of continuous farming, pastures entering the agricultural cycle (CG),
and naturalized grasslands (NG). The study was carried out in fields of Chivilcoy
(34°53'49 S, 60°01'09 W, elev. 60 m) and Navarro (34°51’30 S, 59°12’25 W, elev. 43 m),
Buenos Aires Province, Argentina. For each of the three uses, three fields were selected
as replicates, with three soil samples per replicate and sample date (10) for a total of 216
samples analyzed. Collembolans (Hexapoda: Collembola) were extracted and identified
to family level. Five families were found: Hypogastruridae, Onychiuridae, Isotomidae,
Entomobryidae, and Katiannidae. Soils were also characterized by means of physical
and chemical analyses. The index of degree of change of collembolan diversity was calculated
with the biological data. The results show that the biological index of degree of
change can detect soil use effects on the collembolan community. Somewhat surprisingly,
the index showed that the diversity of collembolans was higher in the high anthropic
impact site AG, followed by CG and lowest in NG. The results also show that collembolan
families respond differently to soil use. The families Hypogastruridae, Onychiuridae, and
Isotomidae presented differences between systems. Therefore, collembolan community
structure can be a useful tool to assess agricultural practices´ impacts on soil.Con el objetivo de evaluar el efecto que produce el impacto antrópico sobre la
estructura de la comunidad de colémbolos, tres usos diferentes del suelo fueron investigados:
campos de agricultura (AG) con 50 años de agricultura continua, pasturas
ingresando al ciclo agrícola (CG) y campos naturalizados (NG). El estudio fue llevado
a cabo en campos de los partidos de Chivilcoy (34°53'49 S, 60°01'09 W, elev. 60 m) y
Navarro de la provincia de Buenos Aires, Argentina. Para cada uno de los tres usos del
suelo, tres campos fueron seleccionados como réplicas. Cada muestreo consistió en
tres muestras de suelo por réplica y por fecha de muestreo (10) para un total de 216
muestras recolectadas y analizadas. Los colémbolos fueron extraídos de las muestras
e identificados a nivel de familia. Se identificaron cinco familias: Hypogastruridae,
Onychiuridae, Isotomidae, Entomobryidae y Katiannidae. Los suelos fueron además
caracterizados mediante análisis físicos y químicos. Con los datos biológicos se calculó
el índice de grado de cambio de la diversidad de colémbolos. Los resultados muestran
que el índice biológico del grado de cambio puede detectar los efectos del uso del suelo
sobre la comunidad de colémbolos. Sorpresivamente, el índice muestra que la diversidad
de colémbolos medida a través del índice de grado de cambio es más alta en los
sitios de mayor impacto antrópico (AG), seguido de CG y la menor diversidad en el sitio
de menor impacto (NG). Los resultados muestran además que las familias de colémbolos
responden de manera diferente al uso del suelo. Las familias Hypogastruridae,
Onychiuridae e Isotomidae presentaron diferencias entre los usos. En consecuencia, la
estructura de la comunidad de colémbolos puede ser una herramienta útil para evaluar
el impacto en el suelo de las prácticas agrícolas.Fil: Sandler, Rosana Veronica.
Universidad Nacional de LujánFil: Falco, Liliana B..
Universidad Nacional de LujánFil: Di Ciocco, César A..
Universidad Nacional de LujánFil: Castro Huerta, Ricardo.
Universidad Nacional de LujánFil: Coviella, Carlos E..
Universidad Nacional de Lujá
Molecular structure and polymorphism of a cyclohexanediol: trans-1,4-cyclohexanedimethanol
This study aims to investigate the molecular structure and polymorphism of trans-1,4-cyclohexanedimethanol,
including the bi-axial/bi-equatorial equilibrium and the nature of the intermolecular H-bond networks in
condensed phases created by the hydroxyl group torsions. The full conformational space of the single
molecule was explored by MP2 calculations, showing that the optimized bi-equatorial conformers have
similar stability and the bi-axial ones have much higher energies. The hydroxymethyl substituents have
preference for gauche/anti or gauche+/gauche− conformations. Polymorphic forms were generated by
crystallization from solutions and by cooling the melt, which were characterized by a combination of
techniques: DSC, PLTM and XRD. Two polymorphs were isolated and their crystal structures were solved
by direct methods based on single-crystal X-ray analysis. Both were found to contain two of the most
stable conformers found in the computational calculations. The influence of H-bonding in the polymorphic
structures was verified by analysis of the structural differences between the geometries present in
the polymorphs determined by XRD and their single molecule counterparts resulting from the theoretical
calculations. The bi-axial conformations are destabilized over the bi-equatorial ones in isolated and
crystalline forms of trans-1,4-cyclohexanedimethanol
Surface superconductivity in multilayered rhombohedral graphene: Supercurrent
The supercurrent for the surface superconductivity of a flat-band
multilayered rhombohedral graphene is calculated. Despite the absence of
dispersion of the excitation spectrum, the supercurrent is finite. The critical
current is proportional to the zero-temperature superconducting gap, i.e., to
the superconducting critical temperature and to the size of the flat band in
the momentum space
Co-crystals of diflunisal and isomeric pyridinecarboxamides – a thermodynamics and crystal engineering contribution
Diflunisal is an anti-inflammatory, non-steroidal drug, class II of the Biopharmaceutical Classification System, which has recently been the subject of renewed interest due to its potential for use in the oral therapy of familial amyloid polyneuropathy. In this study, a thermodynamics based approach is used to investigate binary mixtures (diflunisal + picolinamide and diflunisal + isonicotinamide) in order to identify solid forms that are potentially useful to improve the biopharmaceutical performance of this active pharmaceutical ingredient. Special emphasis is placed on the research of co-crystals and on the influence of structural changes in the pyridinecarboxamide co-former molecules for co-crystal formation with diflunisal. The thermodynamics based methodology described by ter Horst et al. in 2010 indicates that the formation of co-crystals is thermodynamically feasible for both systems. The binary solid–liquid phase diagrams were built and allowed unequivocal identification of the formation of co-crystals of diflunisal with each of the two isomers and also their stoichiometry of 1 : 1, (diflunisal : co-former) in the case of pyridine-2-carboxamide (picolinamide) and (2 : 1) for pyridine-4-carboxamide (isonicotinamide). Two binary eutectic mixtures, potentially relevant for pharmaceutical application, were also identified. Infrared spectroscopy allowed the identification of the acid⋯N-pyridine heterosynthon in the three co-crystals formed by diflunisal with the isomeric pyridinecarboxamides. However, the results clearly differentiated pyridine-2-carboxamide from pyridine-3-carboxamide and pyridine-4-carboxamide, that share similar crystalline arrangements, at least with respect to the supramolecular synthons
Bio-based superabsorbent hydrogels for nutrient-controlled release
The drought is characterized by a low water precipitation rate, with strong impact on the crop productivity, threaten global food production. In this context, the use of soil amendments, such as superabsorbent hydrogels constitute a potential technology for water use efficiency and increase crop yields. In this work, it was synthesised a cellulose-based hydrogel, carrying out its characterisation, evaluated its environmental safety and its potential to be used as a soil amendment. The hydrogel was successfully synthesised using a simple process and inexpensive reagents. The hydrogel showed pH of 6.0 to 7.5 and conductivity below 10.0 µS cm-1. The FTIR showed a low intensity peak in the crystallinity region, which was supported by the low crystallinity index (27.3 % ± 0.6) verified by PXRD analysis. The swelling capacity reached more than 200 g of water, the hydrogel showed good resistance to osmotic pressure and high thermostability, which favours the application in hot and arid areas. Regarding the safety evaluation, no potentially hazardous compound was detected, nor was there any adverse effect on soil microrganisms. In addition, the hydrogel was found to be safe for use during sowing and for promoting seedling development. In the green pot experiment, the hydrogel demonstrated a significant increase in maize biomass, root biomass and potential to serve as a reservoir for soil nutrients. In conclusion, the superabsorbent hydrogel exhibited promising characteristics for use as a soil amendment, scalability potential and constitutes a sustainable alternative for agricultural applications.info:eu-repo/semantics/publishedVersio
Procedimento objetivo para a garantia de qualidade de dados de radiação solar
Se propone un procedimiento objetivo para la garantía de calidad de los datos de irradiancia solar disponibles. El trabajo establece la unión de procedimientos ya difundidos en la literatura (filtros físicos y estadísticos) - juntamente con algunos ajustes propuestos - y la utilización de procedimientos inéditos (e.g. box whiskers o diagramas de caja) en lo que se refiere a la garantía de calidad de datos solarimétricos. Para la obtención de los resultados, fue aplicado el procedimiento a datos de la red SONDA, en las estaciones Petrolina - PE y Brasilia-DF. Las dos series temporales tuvieron menos de 10% de datos rechazados de irradiancia solar en sus componentes global, directa y difusa.In order to enable the use of reliable data, it is proposed an objective procedure for the quality assurance of solar radiation data. This work establishes the union of already diffused procedures in the literature (physical and statistical tests) – along with some adjustments – and the use of unpublished procedures in the quality assurance of solar radiation data (e.g. box whiskers). To obtain the results, the procedure was applied on data from the SONDA network, in stations located at Petrolina – PE and Brasília – DF, both at Brazil. All the time series had less than 10% of rejected solar radiation data.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES
Systematic assessment of fluid responsiveness during early septic shock resuscitation: secondary analysis of the ANDROMEDA-SHOCK trial
BACKGROUND: Fluid boluses are administered to septic shock patients with the purpose of increasing cardiac output as a means to restore tissue perfusion. Unfortunately, fluid therapy has a narrow therapeutic index, and therefore, several approaches to increase safety have been proposed. Fluid responsiveness (FR) assessment might predict which patients will effectively increase cardiac output after a fluid bolus (FR+), thus preventing potentially harmful fluid administration in non-fluid responsive (FR-) patients. However, there are scarce data on the impact of assessing FR on major outcomes. The recent ANDROMEDA-SHOCK trial included systematic per-protocol assessment of FR. We performed a post hoc analysis of the study dataset with the aim of exploring the relationship between FR status at baseline, attainment of specific targets, and clinically relevant outcomes. METHODS: ANDROMEDA-SHOCK compared the effect of peripheral perfusion- vs. lactate-targeted resuscitation on 28-day mortality. FR was assessed before each fluid bolus and periodically thereafter. FR+ and FR- subgroups, independent of the original randomization, were compared for fluid administration, achievement of resuscitation targets, vasoactive agents use, and major outcomes such as organ dysfunction and support, length of stay, and 28-day mortality. RESULTS: FR could be determined in 348 patients at baseline. Two hundred and forty-two patients (70%) were categorized as fluid responders
Acoustically Levitated Whispering-Gallery Mode Microlasers
Acoustic levitation has become a crucial technique for contactless manipulation in several fields, particularly in biological applications. However, its application in the photonics field remains largely unexplored. In this study, we implement an affordable and innovative phased-array levitator that enables stable trapping in the air of micrometer dye-doped droplets, thereby enabling the creation of microlasers. For the first time, this paper presents a detailed performance of the levitated microlaser cavity, supported by theoretical analysis concerning the hybrid technology based on the combination of whispering-gallery modes and acoustic fields. The pressure field distribution inside the acoustic cavity is numerically solved and qualitatively matched with the schlieren deflectometry technique. The optical lasing features of the levitated microlasers are highly comparable with those devices based On-a-Chip registering maximum Q-factors of ~ 105, and minimum lasing thresholds ~ 150 nJ cm−2. The emission comb is explained as a sum of multiple individual-supported whispering-gallery modes. The use of novel touchless micrometric lasers, produced with an acoustic levitator brings new technological opportunities based on photonic-acoustic technological platforms
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