Rendiconti Lincei-Scienze Fisiche E Naturali最新文献

Abstract

This study investigated the impact of biochars on some soil properties, plant growth, nutrient concentrations and uptakes after a 4-year application. Biochars produced at pyrolysis temperatures of 300, 500, and 700 °C were applied to the microplots at a rate of 30 t ha⁻¹ in 2017. In 2020–2021 growing season, basal fertilizations were applied to the microplots before sowing wheat. The results showed that biochar applications had no significant effect on soil pH, EC, and CaCO₃, although they increased cation exchange capacity and organic matter content. Available nutrient concentrations were not affected positively in general. While biochar applications enhanced vegetative growth and the straw yield, the grain yield decreased. Moreover, straw and grain nutrient concentrations did not vary with biochar applications, but the total nutrient uptake increased. Positive correlations were determined between the carbon sequestration potential of the soils and total yield. In addition, it was revealed that the effect of biochar applications on soil physical properties did not create a significant variation. According to the principal component analysis, the properties with the lowest effect were found to be EC of the soils. Findings from this study indicated that biochar did not directly affect plant growth by providing nutrients to the soil or increasing the amount of available nutrients; however, it can stimulate plant growth by improving some soil characteristics.

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Abstract

In the last years, state-to-state molecular dynamics simulations of some basic elementary processes, occurring at the gas–surface interface in a wide range of temperatures and collision energies, have been performed by adopting new potential energy surfaces. In this contribution, our attention is mostly addressed to the role of long-range forces, determining the physisorption of gaseous molecules on the surface. Such forces, formulated in terms of the improved Lennard–Jones interaction potential model, control the formation of precursor or pre-reactive state that plays a crucial role in the dynamical evolution of molecules impinging on the surface in the range of low–intermediate collision kinetic energies. The study focuses on the collisions of H₂, O₂, N₂ and CO, initially in their ground and excited vibro-rotational levels, on a graphite surface. The resulting dispersion coefficients, which control the capture of impinging molecules, are compared and found in good agreement with those available in the literature. New selectivity and peculiarities of scattered molecules, crucial to control the kinetics of elementary chemical processes occurring at the gas–surface interfaces under thermal and sub-thermal conditions, of interest in different applied fields, are highlighted.

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Abstract

Ficus palmata Forssk (Moraceae) and Calotropis procera (Aiton) Dryand (Asclepidaceae) are medicinally important plants. Traditionally, Ficus palmata Forssk is well known to cure gastric and diabetic problems. Both plants are found useful in the treatment of cancerous complications and skin eruptions. The present study was aimed to assess bioactivities of selected plants. Cytotoxicity (brine shrimp lethality assay), antioxidant (ABTS, DPPH, phosphomolybdate and reducing power assay), antimicrobial (disc diffusion method) and phytochemical screening was performed to analyze their activities. Crude extract of leaves and fruit of both plants was prepared in two polar solvents, i.e. methanol and chloroform. Significant cytotoxic potential was shown by fruit of both plants with LD₅₀ values of 80.34 and 93.83 µg/mL by Calotropis procera (Aiton) Dryand methanolic extract and F. palmata chloroform extract, respectively. Methanol extracts of leaves of both plants revealed significant antioxidant, antibacterial and antifungal activity. F. palmata leaves methanol extract showed strong antioxidant activity among the tested samples and the LC₅₀ values were 10.39, 14.63 and 19.28 µg/mL in phosphomolybdate, ABTS and DPPH assays, respectively. Promising microbial growth inhibition was observed at 25 µg/mL. The observed bioactivities are consistent with the presence of valuable phytochemicals: alkaloids, flavonoids, tannins, glycosides and saponins. Due to the strong antibacterial, cytotoxic and antioxidant potential endowed by selected plant extracts, these are supposed to be potential candidates for biopharmaceutical and nutraceutical industries. Further work explicating the structural details and isolation of phytochemicals from selected plant species would be recommended.

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The variability in the magnetic activity of the Sun is the main source of the observed changes in the plasma and electromagnetic environments within the heliosphere. The primary way in which solar activity affects the Earth’s environment is via the solar wind and its transients. However, the relationship between solar activity and solar wind is not the same at the Space Weather and Space Climate time scales. In this work, we investigate this relationship exploiting five solar cycles data of Ca II K index and solar wind parameters, by taking advantage of the Hilbert–Huang Transform, which allows to separate the contribution at the different time scales. By filtering out the high-frequency components and looking at decennial time scales, we confirm the presence of a delayed response of solar wind to Ca II K index variations, with a time lag of (sim) 3.1-year for the speed and (sim) 3.4-year for the dynamic pressure. To assess the results in a stronger framework, we make use of a Transfer Entropy approach to investigate the information flow between the quantities and to test the causality of the relation. The time lag results from the latter are consistent with the cross-correlation ones, pointing out the presence of a statistical significant information flow from Ca II K index to solar wind dynamic pressure that peaks at time lag of 3.6-year. Such a result could be of relevance to build up a predictive model in a Space Climate context.

Oceanography, or Oceanology, is a very broad name covering all the traditional sciences (physics, chemistry, biology etc.) which can be studied in the ocean context. Hence the distinction must be made using the specific names of Physical, Chemical or Biological Oceanography. This particular review is devoted to the history of Physical Oceanography, a discipline which remained at the empirical stage until roughly the middle of last century, with a slow development of the rigorous, mathematical approach and analysis required to fully understand the processes and dynamics at all space/time scales. This review wants to introduce the uninformed reader to this relatively new science, providing a concise but hopefully comprehensive outline of the milestones of its history, from the adventurous beginnings of the past centuries, to the successive, very recent theoretical and observational advances. In this progress, the scientific “giants” who made possible these advances are also presented. Their choice constitutes not only the author’s personal opinion but that of the oceanographic community at large which recognizes their crucial impact in making physical oceanography the quantitative, exact science of today. It is the author’s privilege to have personally known most of them, not only as teachers but as mentors and friends.

Experimental, theoretical and computational chemical kinetics contribute to progress both in molecular and materials sciences and in biochemistry, exploring the gap between elementary processes and complex systems. Stationary state quantum mechanics and statistical thermodynamics provide interpretive tools and instruments for classical molecular dynamics simulations for stable or metastable structures and near-equilibrium situations. Chemical reaction kinetics plays a key role at the mesoscales: time-dependent and evolution problems are typically tackled phenomenologically, and reactions through intermediates and transition states need be investigated and modelled. In this paper, scaling and renormalization procedures are developed beyond the Arrhenius equation and the Transition State Theory, regarding two key observables in reaction kinetics, the rate “constant” as a function of temperature (and its reciprocal, the generalised lifetime), and the apparent activation energy (and its reciprocal, the transitivity function). Coupled first-order equations—dependent on time and on temperature—are formulated in alternative coupling scheme they link experimental results to effective modelling, or vice versa molecular dynamics simulations to predictions. The passage from thermal to tunnelling regimes is uniformly treated and applied to converged quantum mechanical calculations of rate constants available for the prototypical three-atom reactions of fluorine atoms with both H₂ and HD: these are exothermic processes dominated by moderate tunnel, needing formal extension to cover the low-temperature regime where aspects of universal behaviour are shown to emerge. The results that have been validated towards experimental information in the 10–350 K temperature range, document the complexity of commonly considered “elementary” chemical reactions: they are relevant for modelling atmospheric and astrophysical environments. Perspectives are indicated of advances towards other types of transitions and to a global generality of processes of interest in applied chemical kinetics in biophysics and in astrochemistry.

In the last 50 years, the impressive results on chemical kinetics from crossed molecular beam experiments have been assisted by theoretical and particularly computational progress, among which are: (1) the design and implementation of the SIMBEX (SImulation of Molecular Beam EXperiments) procedure on parallel and distributed computers aimed at rationalizing the dynamical behavior of the investigated systems on the ab initio computed molecular interactions; (2) the establishing of theoretical and computational research and educational networks (like the Quantum Reactive Scattering and European Chemistry Thematic Network), the assembling of virtual research communities (like the meta- and the grid-chemistry ones within the Collaboration in Science and Technology (COST) initiatives to enhance synergic and cooperative work levering on highly productive platforms; (3) the participation in the management of both the Italian and the European grid infrastructures initiatives; (4) the development of molecular open science-enabled cloud services within the European Open Science Cloud (EOSC). Levering on the mentioned collaborative efforts, important open science initiatives have been implemented. The present paper illustrates a prototype model apparatus for the production of methane out of CO₂ using renewable energy sources and a prosumer (producer–consumer) model for delivering online chemistry competence tests. Finally, a suggestion is made to establish networked local services of the academy for high school education.