National University of Tucumán

This study explores two fundamentally different behaviors of benznidazole in its various forms. First, the charge transport behavior describes how electric charges move through the molecule, while the nonlinear optical properties reflect how the material responds to intense electromagnetic fields. These behaviors were analyzed using the non-equilibrium Green’s function (NEGF) formalism combined with density functional theory (DFT). In this study, two s-cis forms (C2 and C4) and one s-trans form were investigated as molecular switches, while C2 and C4 were specifically evaluated for nonlinear optical (NLO) activity. The influence of electrode material (Pt, Au, Ag) and binding sites (bridge, hollow, top) on transport efficiency was assessed, with platinum at the bridge site providing optimal current output and switching performance. Among all configurations, the C4 form showed the highest current output (1556 nA). The current ratio between C4 and Trans was maximal, indicating effective switching. This enhanced conductivity was associated with a narrower HOMO–LUMO energy gap and molecular projected self-consistent Hamiltonian (MPSH) orbitals. Additional descriptors, including transmission pathways, molecule–electrode coupling, transmission spectra, and stabilization energies (E2), further supported these findings. Beyond charge transport, benznidazole also exhibited a strong NLO response. Calculations revealed hyperpolarizability values far exceeding those of the benchmark urea. Complementary descriptors, including dipole moments, global hardness, and softness, reinforced the NLO activity, identifying the C2 form as particularly efficient for optical modulation. These findings suggest that benznidazole-based systems hold strong promise for integration into nanoscale molecular electronics and photonic devices.

Biostimulants with protective effects include plant extracts, which are considered a sustainable alternative to synthetic fungicides. In this study, we evaluated the effects of an alkaloid fraction obtained from the leaves of Neltuma nigra on soybean seedlings. Soybean seedlings were grown in the greenhouse. Catalase activity was assessed in vitro by adding the alkaloid fraction to enzyme extracts, whereas in a separate greenhouse assay seedlings were treated with the alkaloid fraction at 50, 150, or 600 µg leaf⁻1 and lipid hydroperoxides, and total antioxidant capacity were measured in the treated tissues. The antifungal efficacy of the alkaloid fraction was evaluated based on the percentage of seedling lesion inhibition. Results showed that the alkaloid fraction inhibited catalase activity in a dose-dependent manner, similar to the effect observed with the known catalase inhibitor hydroxylamine. In addition, total antioxidant capacity decreased compared to the control, whereas lipid hydroperoxide levels remained unchanged. These findings suggest that the alkaloid fraction may serve as a potential ingredient for phytogenic pesticides, offering an environmentally friendly complement to synthetic fungicides. Overall, this study contributes to a better understanding of the role of the biostimulants with protective effects in crops protection.

Anthropogenic expansion extensively covers Earth's cultivable surface, increasing pressure on ecosystems and leading to significant biodiversity loss and widespread pollution, particularly impacting freshwater systems. Diffuse agricultural pollution, stemming from agrochemical runoff into river channels, represents a critical threat to aquatic biota. Mayflies (Ephemeroptera), with their sensitive obligately subaquatic immature stages, are excellent bioindicators of water quality. This study investigated how mayfly communities in Northwestern Argentina, a region dominated by sugarcane and citrus cultivation, respond to such diffuse pollution. Our primary objective was to determine if mayfly community characteristics (total abundance, species richness, and assemblage composition) exhibit changes downstream of cultivated areas compared to upstream sections. We collected 277 D-net samples across five rivers, at both upstream and downstream sites relative to cultivation, each two months (over nine visits) during 2009-2010. The impact of agriculture at downstream sites on mayfly abundance and richness is not uniform across all rivers, with significant reductions observed in some rivers, but not others. Non-metric multidimensional scaling and permutational multivariate analysis of variance confirmed significant effects of site, river, and their interaction on community composition. Notably, the difference in composition between upstream and downstream sites was significant. SIMPER analysis identified Baetodes as the primary contributor to upstream-downstream dissimilarities, being more abundant upstream. Indicator species analysis highlighted Haplohyphes baritu, Lachlania sp., and Nanomis galera as indicators of specific upstream conditions, while no species were exclusive indicators of downstream sites, suggesting downstream communities may be a depauperate subset. These findings underscore the context-dependent impact of diffuse agricultural pollution on mayfly communities and their utility as bioindicators.

Since the first description of an Azospirillum-like bacterium in 1925 by Martinus Beijerinck in The Netherlands, this genus has become a cornerstone of plant–microbe interactions and sustainable agriculture worldwide. Over the past century, Azospirillum has been extensively studied for its ability to promote plant growth, enhance stress tolerance, and contribute to nutrient acquisition, particularly in cereals and legumes. These functions are mediated by multiple mechanisms, including nitrogen fixation, phytohormone production, and the modulation of the root architecture by effector molecules. This review presents a comprehensive synthesis of the historical and current research on Azospirillum and its impact in agriculture and beyond. It explores its taxonomic expansion, physiological versatility, genetic manipulation, and interactions with plant hosts and other microorganisms. It also examines its agronomical impact on extensive and intensive cropping systems, both individually and mixed in microbial consortia. Advances in formulation technologies and regulatory frameworks for commercial inoculants are discussed, as well as cutting-edge tools such as artificial intelligence and multi-omics integration that are reshaping how we understand and deploy this bacterium. Beyond agriculture, Azospirillum has proven valuable in environmental contexts such as revegetation of degraded lands, bioremediation of contaminated soils, and ecological restoration in arid zones. Its capacity to colonize diverse hosts, survive extreme conditions, and contribute to ecosystem processes underscores its potential far beyond agriculture. One hundred years after its first scientific mention, Azospirillum remains not only relevant but also vital. As the world moves toward more sustainable agricultural and ecological systems, this review reaffirms the legacy and promise of this genus.

Abstract This contribution is a condensed proceedings version of results previously published in a journal article (see Ref. [1]). We additionally use the proceedings format to expand the dataset employed in the analysis and to further discuss its dependence on the solar cycle and the associated physical implications. Using hourly OMNI proton-density data near the L1 Lagrange point over 44 consecutive years (1980–2024), we show that proton density measurements preserve robust nonlinear signatures: (i) fat-tailed increment statistics well described by q -Gaussians, (ii) slow, non-exponential relaxation consistent with q -exponential decay of correlations, and (iii) multifractal scaling across temporal scales. These three features are quantitatively linked by the Tsallis q -triplet ( q stat , q rel , q sens ), for which we obtain year-by-year values and their mean. By comparing interannual variability of the q -triplet with standard proxies of solar activity, we provide evidence that part of the dispersion in the yearly estimates may be organized by solar-cycle modulation, motivating a regime-dependent interpretation. The long-term persistence of the q -triplet supports a physically consistent picture of intermittent compressible turbulence and long-range correlations in near-Earth solar-wind proton density, with implications for multiscale solar-wind driving of space-weather conditions.