A Method to Obtain a Maxwell–Boltzmann Neutron Spectrum at kT = 30 keV for Nuclear Astrophysics Studies

AbstractA method to shape the neutron energy spectrum at low-energy accelerators is proposed by modification of the initial proton energy distribution. A first application to the superconductive RFQ of the SPES project at Laboratori Nazionali di Legnaro is investigated for the production of a Maxwell–Boltzmann neutron spectrum at kT = 30 keV via the 7Li(p, n)7Be reaction. Concept, solutions and calculations for a setup consisting of a proton energy shaper and a lithium target are presented. It is found that a power dentisity of 3 kW cm−2 could be sustained by the lithium target and a forward-directed neutron flux higher than 1010 s−1 at the sample position could be obtained. In the framework of the SPES project the construction of a LEgnaro NeutrOn Source (LENOS) for Astrophysics and for validation of integral nuclear data is proposed, suited for activation studies on stable and unstable isotopes

Physicochemical characterization and antimicrobial activity against Erwinia amylovora, Erwinia vitivora, and Diplodia seriata of a light purple Hibiscus syriacus L. Cultivar

Phytochemicals are essential raw materials for the production of formulations that can be helpful in crop protection. In particular, Hibiscus spp., which are often used in traditional medicine, are rich in potential bioactive molecules. This study presents an analysis of the thermal, vibrational, and phytochemical characteristics of a light purple variety of Hibiscus syriacus, using thermal gravimetric and differential scanning calorimetry, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectroscopy techniques. Further, with a view to its valorization, the antimicrobial activity of its extracts has been investigated in vitro against Erwinia amylovora (the phytopathogen responsible for fire blight in apples, pears, and some other members of the family Rosaceae), Erwinia vitivora (the causal agent of the “maladie d’Oléron” in grapevines), and Diplodia seriata (responsible for “Bot canker”). Higher heating values and thermal features showed similarities with kenaf biomass. The main compounds identified in the hydro-methanolic extracts were: in flowers, 1-heptacosanol, heptacosane, 1-tetracosanol, hexadecenoic acid, 9,12,15-octadecatrienoic acid, and 9,12-octadecadienoic acid; and in leaves, the coumarin derivative 4,4,6,8-tetramethyl-2-chromanone, vitamin E, phytol, and sitosterol. MIC values of 500 and 375 μg·mL−1 were obtained against E. amylovora for flower and leaf extracts, respectively, upon conjugation with chitosan oligomers (to improve solubility and bioavailability). In the case of E. vitivora, MIC values of 250 and 500 μg·mL−1, respectively, were registered. Regarding the antifungal activity, EC90 values of 975.8 and 603.5 μg·mL−1, respectively, were found. These findings suggest that H. syriacus (cv. ‘Mathilde’) may be a promising source of antimicrobials for agriculture

Vibrational analysis and thermal behavior of salvia hispanica, nigella sativa and papaver somniferum seeds

Introduction: Salvia hispanica L., Nigella sativa L. and Papaver somniferum L. are involved in opiate-dependent behavior. It is known that the seeds of these three herbs contain high amounts of antioxidants, which are helpful in disease prevention, but further research is needed on some of their other phytochemical components (terpene alkaloids, benzoquinones and others), which are claimed to affect human opioid receptors. Methods: Seeds from the three afore mentioned plants have been studied by ATR-FTIR vibrational spectroscopy and thermo analytical techniques (TG/DTG, DTA and DSC). Results: The infrared spectrum has confirmed the presence of the ester carbonyl of terpenoid alkaloids (such as nigellamine) and the fully conjugated cyclic dione structure of quinones (e.g., thymoquinone). As regards the thermal stability of these seeds, small differences have been observed in their thermal profiles (endothermic effects at around 333C for chia, 268C for black cumin and 319C for poppy seeds), which can be ascribed to their different content in carbohydrates. Conclusions: The functional groups of the main active constituents and the thermal behavior of these three seeds have been elucidated

On the probable composition of ‘Jamaican stone’ aphrodisiac

A dangerous aphrodisiac, commonly known as ‘Jamaican stone’, banned by the U.S. Food and Drug Administration, has been studied by vibrational spectroscopy in order to solve the controversy on its composition. The results of the ATR-FTIR analysis revealed the presence of the a-pyrone ring, which is characteristic of bufadienolides from toad venom and bulbs of squill (Drimia maritima (L.) Stearn). This conclusion was reached after a comparative study with the spectra for phytochemicals derived from gambir and cat''s claw, two Uncaria species also preconized as aphrodisiacs and deemed as possible constituents of the ‘stone’. Owing to their physiologic similarities to digoxin, bufadienolides have been shown to produce a toxic profile similar to that of digoxin, although the lack one of the side chains found on digoxin should allow the use of hemodialysis to treat ‘Jamaican stone’ overdose

Valorization of Cistus ladanifer and Erica arborea shrubs for fuel: Wood and bark thermal characterization

As a form of upgraded biomass characterized by its high energy density, low production costs, and low process energy requirements, wood pellets are an environmentally friendly fuel allowing for carbon neutral heating with high energy efficiency. In this work, the suitability of a valorization of the woods from the two most representative shrub species from the Iberian Peninsula (namely Cistus ladanifer and Erica arborea) for heating has been assessed. Whereas Erica arborea met the requirements of ISO 17225-2:2014 for ENplus-B class (the calorific content for both wood and bark was high and not significantly different, and the ash content was permissible for specimens with branch diameter =2, 8 cm), Cistus ladanifer was in the limit of the normative and only met the requirements in terms of acceptable ash percentage (1, 9%) and heating value (19 kJ·g-1) for old specimens with branch diameters > 3, 4 cm. Consequently, while the harvest of E. arborea for its use as fuel does not need to be selective, that of C. ladanifer should be limited to the most robust specimens and foliage should be avoided

An erbium(III)-based NIR emitter with a highly conjugated ß-diketonate for blue-region sensitization

The sensitization of lanthanide complexes in the visible region is of particular interest for practical applications such as labeling, biological analysis and optoelectronics. A visible-light sensitized Er3+complex based on the use of a highly conjugated ß-diketonate (1, 3-di(2-naphthyl)-1, 3-propanedione, Hdnm) and 5-nitro-1, 10-phenanthroline (5NO2phen) as an ancillary ligand, [Er(dnm)3(5NO2phen)], has been synthesized, fully characterized and its photophysical properties have been investigated. Suitably expanded p-conjugation in the complex molecule makes the excitation window red-shifted to the visible region (up to 550 nm). Efficient energy transfer by antenna effect results in 1.53 µm emission from the Er3+ion

Broadband transverse susceptibility in multiferroic Y-type hexaferrite Ba0.5_{0.5}Sr1.5_{1.5}Co2_2Fe12_{12}O22{22}

Single phase multiferroics in which ordered magnetic and ferroelectricity coexist, are of great interest for new multifunctional devices, and among them Y-type hexaferrites are good candidates. Transverse susceptibility measurements, which have been proved to be a versatile tool to study singular properties of bulk and nanoparticle magnetic systems, have been carried out with a broadband system on polycrystalline Y type hexaferrites with composition Ba$_{0.5}$Sr$_{1.5}$Co$_2$Fe$_{12}$O${22}$, optimal to exhibit multiferroic properties. In the temperature range 80-350 K transverse susceptibility measurements with DC fields up to $\pm$5000 Oe reveal different behaviour depending on the sintering temperature. The thermal evolution of the anisotropy field peak exhibit four regions with different slopes: positive in 80-130 K, negative in 130-200 K, constant in 200-280 K and negative in 280-350 K, which can be considered a signature of spin transitions in this compound.Comment: arXiv admin note: substantial text overlap with arXiv:2401.1614

Species Distribution Models at Regional Scale: Cymodocea nodosa Seagrasses

Despite their ecological and socio-economic importance, seagrasses are often overlooked in comparison with terrestrial ecosystems. In the Canarian archipelago (Spain), Cymodocea nodosa is the best-established species, sustaining the most important marine ecosystem and providing ecosystem services (ES) of great relevance. Nevertheless, we lack accurate and standardized information regarding the distribution of this species and its ES supply. As a first step, the use of species distribution models is proposed. Various machine learning algorithms and ensemble model techniques were considered along with freely available remote sensing data to assess Cymodocea nodosa’s potential distribution. In a second step, we used InVEST software to estimate the ES provision by this phanerogam on a regional scale, providing spatially explicit monetary assessments and a habitat degradation characterization due to human impacts. The distribution models presented great predictive capabilities and statistical significance, while the ES estimations were in concordance with previous studies. The proposed methodology is presented as a useful tool for environmental management of important communities sensitive to human activities, such as C. nodosa meadows.En prensa0,64

Vibrational and thermal studies of essential oils derived from Cistus ladanifer and Erica arborea shrubs

Essential oils from the two most representative shrub species from the Iberian Peninsula (namely Cistus ladanifer L. and Erica arborea L.) have been characterized by Fourier transform infrared spectroscopy (FTIR) and thermoanalytical techniques (TG/DTG and DSC). Vibrational spectra have been compared with those of components of the plants, and with those of oils, gums and resins from other species. The different content in terpenoids of C. ladanifer oil (mainly mono-and sesquiterpenoids) and E. arborea oil (mainly triterpenoids) is reflected in the ATR-FTIR by the position of the bands at around 2873 cm-1, 1730 cm-1 and 1678 cm-1. As regards their thermal behavior, C. ladanifer-derived oil evinced higher thermal stability than that of obtained from E. arborea: The pyrolysis of the former was sensitized at 210°C, whereas for the later it occurred at 143°C. These temperatures are high enough to state that thermolabile constituents such as terpenoids are conserved in the hydrodistillation and that this extraction process ensures the recovery of the main constituents of both essential oils

Observational Δν\Delta\nu-ρˉ\bar\rho relation for δ\delta Sct stars using eclipsing binaries and space photometry

Delta Scuti ($\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\delta$ Sct stars.Comment: 11 pages, including 2 pages of appendix, 2 figures, 2 tables, accepted for publication in ApJ