Search Results (84)

The complex dielectric permittivity has been studied with the waves of millimeter wavelength for rare earth manganate and titanate and LiCoPO₄ and LiNi_0.5Co_0.5PO₄ orthophosphate composites. The measurements are carried out at frequencies of 26 to 38 GHz via measurements of transmission and reflection coefficients through a plate. A special method on how to extract the real and imaginary parts of dielectric permittivity is applied. Discussion is conducted on a nonmonotonic type of the frequency dependences for both real and imaginary parts of permittivity, and it has been shown that relaxation is non-Debye. The Cole–Cole, Havriliak–Negami, and Kohlrausch–Williams–Watts models cannot also explain the nonmonotonic frequency dependence of the real part of dielectric permittivity. Investigation of the structure and phase composition of nanocomposites has been carried out. Full article

Background/Objectives: Antimicrobial resistance represents a critical global health challenge that has been exacerbated by the significant decline in antibiotic development. Natural product-based drugs, particularly plant-derived phenolic compounds, offer promising alternatives to conventional antibiotics. This study aimed to isolate and characterize a novel phenolic compound from Bacopa procumbens, a Mexican perennial repent plant that is widespread in the Mexican valley and produces a variety of saponins, gastrodin derivatives, and phenolic acids, and to evaluate its antibacterial potential against clinically relevant pathogens. Methods: The hydroalcoholic extraction of B. procumbens was followed by liquid–liquid partitioning with ethyl acetate. The resulting fraction underwent chromatographic separation and purification. The structural elucidation of the isolated compound was performed using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), mass spectrometry (MS-EI), and nuclear magnetic resonance (NMR) techniques. Antimicrobial activity was assessed via a microdilution assay against five bacterial strains, including drug-resistant Staphylococcus species and Gram-negative pathogens. Results: A novel phenolic compound, 5-(p-hydroxybenzoyl) shikimic acid (5pHSA), was isolated and characterized. The compound demonstrated moderate antibacterial activity against methicillin-resistant Staphylococcus haemolyticus and Escherichia coli (minimum inhibitory concentration (MIC) = 100 μg/mL) but showed limited efficacy against Staphylococcus aureus, MRSA, and Klebsiella pneumoniae (MIC > 100 μg/mL). Comparative analysis with the previously isolated compound ProcumGastrodin A revealed structure–activity relationships where the higher lipophilicity of PG-A was correlated with enhanced antimicrobial activity. Conclusions: This study establishes 5pHSA as a novel phenolic compound with moderate antibacterial properties. The findings highlight the importance of molecular polarity and structural complexity in determining antimicrobial efficacy, offering valuable insights into the development of phenolic, acid-based antimicrobial agents to address the growing challenge of antimicrobial resistance. Full article

Urban solid waste (USW) is a promising alternative source of valuable chemical compounds. It is considered an adsorbent material due to its chemical structure, porosity and electronic charge available to form chemical bonds and can be recovered or transformed for use in bioprocesses and industrial applications. This is the case with cigarette butts (CBs), which consist of thousands of substances that can be chemically converted for various purposes. This work showed high efficiency in the production of cellulose mass from the recycling of CBs, a patented technology in operation at the company Poiato Recicla—SP. The lignin-like solid (LLS)—a material obtained from the recycling of cigarette butts (CBs) by catalytic transfer hydrogenation (CTH), under non-rigorous conditions—showed high efficiency in its conversion into molecules of great interest. In the bio-oil obtained, characterized by analyses such as GCMS and RMN 2D HSQC, a mixture of predominantly hydrocarbons (many of them with cyclic and/or branched chains) was identified in almost all the experiments. This method demonstrates the potential of the TCH process for SSLs and completes the recycling chain designed for CBs, promoting their complete conversion into chemical compounds of greater interest. Full article

Hospital-acquired infections (HAIs) previously focused mainly on multidrug-resistant (MDR) bacteria, with less attention on viruses. The COVID-19 pandemic highlighted the importance of controlling viral infections. Human rhinoviruses (HRVs) are among the viruses responsible for HAIs. HRVs are non-enveloped viruses that infect the upper airways after airborne or direct transmission. Due to their lack of a membrane envelope, HRVs exhibit moderate resistance to commonly applied alcoholic disinfectants. Therefore, there is a significant need to develop alternative disinfection and hand sanitation strategies to control HRV infections in healthcare settings without posing a risk to human health. The antimicrobial activity and safety of rhamnolipids and rhamnolipids nano-micelles (RMN) against MDR-bacteria and several viruses, including SARS-CoV-2, were confirmed recently. Also, we previously demonstrated the superior antimicrobial activity of RMN over rhamnolipids. In the current study, molecular docking demonstrated the weak interactions of rhamnolipids with HRV-1A (minor group) compared to HRV-14 (major group), suggesting a superior antiviral activity of rhamnolipids towards major group rhinoviruses. To biologically validate these data, RMN was prepared and characterized, and then antiviral activity against HRV-16 (major group) and HRV-1B (minor group) infection of HeLa cells was assessed. RMN showed a complete inhibition of HRV-16 infection with recovery of 100% of HeLa cell viability. In contrast, only partial inhibition of HRV-1B infection with approximately 50% protection against infection was observed. Therefore, RMN might be recommended as a disinfectant and/or a hand sanitizer component to control the spread of RVs in hospital care settings or elsewhere to reduce the incidence of respiratory infections. Full article

A site-ordered quadruple perovskites, AA′₃B₄O₁₂, can have 3d transition metals at A′ and B sites, and show complex magnetic interactions and behavior. Additional complexity appears when B site-ordered arrangements are realized in AA′₃B₂B′₂O₁₂. In this work, A site-ordered quadruple perovskites, RMn₃Ni₂Mn₂O₁₂ with R = Bi, Ce, and Ho, were prepared by a high-pressure, high-temperature method at about 6 GPa and about 1500 K. The R = Bi and Ce samples were found to crystallize in space group Im-3 with a disordered distribution of Ni²⁺ and Mn⁴⁺ cations in one B site. On the other hand, the R = Ho sample crystallized in space group Pn-3 and showed partial ordering of Ni²⁺ and Mn⁴⁺ cations between two B sites. The structural data (and bond valence sums) suggest that cerium has the oxidation state +3, which is unusual for such perovskites. Magnetic properties were investigated by magnetic susceptibility and specific heat measurements, which showed the presence of one magnetic transition near 36 K for R = Bi; there was evidence for the presence of two magnetic transitions near 27 K and 33 K for R = Ce, and near 10 K and 36 K for R = Ho. Curie–Weiss parameters were estimated for all samples from high-temperature magnetic measurements up to 750 K. The total effective magnetic moment for R = Ce also suggests the presence of Ce³⁺. A magnetic field of 90 kOe had the largest effect on the specific heat of the R = Ho sample, and almost no effects on the specific heat of the R = Bi sample. Full article

Leishmania amazonensis, a cause of cutaneous leishmaniasis in Brazil, is a neglected disease with toxic and inconsistently effective treatments. The parasite’s survival depends on managing oxidative stress, making redox-regulating enzymes potential therapeutic targets. Geopropolis, a resinous product from native stingless bees, shows promising antiparasitic effects. This study aims to evaluate the anti-L. amazonensis activity of geopropolis produced by Melipona bicolor, M. marginara, M. mondury, and M. quadrifasciata (two samples), targeting enzymes responsible for the parasite’s redox balance. Ethanol extracts of geopropolis produced by each bee (BCRL, MRGT, MNDY, MNDA(1), and MNDA(2), respectively) were analyzed for total phenolics and flavonoids. Promastigotes and axenic amastigotes were treated with various extract concentrations, and parasite viability was assessed using the resazurin reduction method. Cytotoxicity was tested on peritoneal macrophages, RAW 264.7, VERO cell lines (MTT assay), and erythrocytes (hemolysis assay). Additionally, mitochondrial dehydrogenase activity, reactive oxygen species (ROS) production, the inhibition of recombinant arginase, and autophagic activity were also evaluated in treated parasites. MRGT showed the highest levels of phenolics (762 mg GAE/g) and flavonoids (345 mg QE/g). MDRY was more effective against promastigote and axenic amastigote forms (IC₅₀ = 168 and 19.7 µg/mL, respectively). MRGT showed lower cytotoxicity against RAW 264.7 and VERO (CC₅₀ = 654 µg/mL and 981 µg/mL, respectively). Erythrocytes exhibited reduced sensitivity to MNDA(2) (HC₅₀ = 710 µg/mL). The activity of dehydrogenases and LiARG was reduced by treating the parasites with the extracts following the induction of ROS and autophagic activity. These results highlight geopropolis extracts as a source of substances with anti-L. amazonensis activity capable of inducing oxidative stress on the parasite. Full article

This study focuses on developing innovative and eco-friendly purification methods for the isolation of bioactive compounds derived from Padina pavonica, a brown abundant macroalga in Djibouti. Three distinct fractions, obtained via liquid-liquid extraction (LLE_FAE), solid-phase extraction (SPE_WE50), and flash chromatography (FC_EtOH20), were selected based on their high phenolic content and antioxidant activities. All fractions were also evaluated for their anti-ageing potential by assessing their ability to inhibit two vital skin-ageing enzymes, tyrosinase and elastase. Structural analysis by ¹H-¹³C HMBC NMR and LC-MS revealed a selectivity of phlorotannins depending on the purification methods. The LLE_FAE fraction exhibited greater structural complexity, including compounds such as phloroglucinol, diphlorethol/difucol, fucophlorethol and bifuhalol, which likely contribute to its enhanced bioactivity compared to the fractions obtained by FC_EtOH20 and SPE_WE50, which were also active and enriched only in phloroglucinol and fucophlorethol. These findings highlight the impact of purification techniques on the selective enrichment of specific bioactive compounds and demonstrated the interest of FC or SPE in producing active phlorotannin-enriched fractions. These two purification methods hold strong potential for innovative cosmeceutical applications. Results are discussed regarding the use of P. pavonica as a promising marine resource in Djibouti to be used for the development of cosmetic industry. Full article

The Spanish Merino is the most significant sheep breed globally due to its economic and cultural importance in human history. It has also had a substantial influence on the development of other Merino and Merino-derived breeds. Historical sources indicate that crossbreeding to produce finer, higher-quality wool was already taking place in the south of the Iberian Peninsula during the Roman era. This evidence suggests that individuals with a racial pattern very similar to that of the modern Merino may have already existed on the peninsula. The presence of the skeletal remains of these animals at various human settlements dated to the late fourth and third millennia BC could provide insights into the genomics of these ancestral sheep. This study analyses ancient DNA extracted from nine skeletal remains from three archaeological sites in Southern Iberia, dated to the third millennium BC. The samples were sequenced and aligned with the ovine genome. The genetic distances observed among the samples indicate a closer relationship between several animals from the Marinaleda (Seville) and Grañena Baja (Jaén) sites. The study of the slaughter/death age profiles identified at La Minilla (La Rambla, Córdoba) suggests an approach centred on meat exploitation, while the data from Marinaleda (Seville) and Grañena Baja (Jaén) indicate the potential exploitation of secondary resources. A review of the composition of these small ruminant herds could provide insights into the type of secondary resource exploitation that may have been prioritised. Our aim is to investigate the presence of distinct production systems, differentiating between those aimed primarily at meat use and those focused on secondary products. This is the first approach to exploring the genetic evidence for sheep livestock related to its productive use during this period and in this geographical area. Full article

ABO₃ perovskite materials with small cations at the A site, especially with ordered cation arrangements, have attracted a lot of interest because they show unusual physical properties and deviations from general perovskite tendencies. In this work, A-site-ordered quadruple perovskites, RMn₃Ni₂Mn₂O₁₂ with R = Nd, Sm, Gd, and Dy, were synthesized by a high-pressure, high-temperature method at about 6 GPa. Annealing at about 1500 K produced samples with additional (partial) B-site ordering of Ni²⁺ and Mn⁴⁺ cations, crystallizing in space group Pn–3. Annealing at about 1700 K produced samples with disordering of Ni²⁺ and Mn⁴⁺ cations, crystallizing in space group Im–3. However, magnetic properties were nearly identical for the Pn–3 and Im–3 modifications in comparison with ferromagnetic double perovskites R₂NiMnO₆, where the degree of Ni²⁺ and Mn⁴⁺ ordering has significant effects on magnetic properties. In RMn₃Ni₂Mn₂O₁₂, one magnetic transition was found at 26 K (for R = Nd), 23 K (for R = Sm), and 22 K (for R = Gd), and two transitions were found at 10 K and 36 K for R = Dy. Curie–Weiss temperatures were close to zero in all compounds, suggesting that antiferromagnetic and ferromagnetic interactions are of the same magnitude. Full article

Biostimulants are an important alternative to improve and promote higher efficiency in cropping systems. Although the biostimulant industry has been developing for several years, there are still areas of opportunity for new sources of biostimulants as well as new ecofriendly extraction techniques that allow for a circular economy and the reuse of waste. Lignin is a heteropolymer that constitutes about 40% of the plant cell wall. A great source of lignin is agrowastes, giving it added value. Recently, its use has been tested in agronomy as a carrier of nutrients and pesticides. Walnuts are produced on a large scale in Northern Mexico, and the shell represents between 15 and 40% of its total weight. However, to obtain this biopolymer, to date, non-environmentally friendly techniques have been used; for this reason, it is necessary to find extraction alternatives to make this proposal sustainable. In this work, the obtaining and characterization of lignin through mild extraction conditions from nutshells and its evaluation as a biostimulant on the growth of tomato seedlings are reported. Lignin was extracted by hydrolysis with a mixture of acetic acid and distilled water (65:35 v/v). The results showed that it was possible to obtain 15% (w/w) lignin using mild solvents, evidenced by thermogravimetric analysis (TGA), proton magnetic nuclear resonance (H-RMN), and infrared (IR). Subsequently, lignin solutions were prepared at different concentrations, 0, 10, 50, and 100 ppm, and applied via foliar weekly to tomato seedlings. A greater fresh weight of the stem was found with 10 and 50 ppm, and the height and the fresh biomass increased with the three concentrations (10, 50, and 100 ppm), concluding that lignin extracted from nutshells using mild conditions can act as a plant biostimulant. Full article

The screening of 166 extracts from tropical marine organisms (invertebrates, macroalgae) and 3 cyclolipopeptides from microorganisms against yeast prions highlighted the potential of Verongiida sponges to prevent the propagation of prions. We isolated the known compounds purealidin Q (1), aplysamine-2 (2), pseudoceratinine A (3), aerophobin-2 (4), aplysamine-1 (5), and pseudoceratinine B (6) for the first time from the Wallisian sponge Suberea laboutei. We then tested compounds 1–6 and sixteen other bromotyrosine and bromophenol derivatives previously isolated from Verongiida sponges against yeast prions, demonstrating the potential of 1–3, 5, 6, aplyzanzine C (7), purealidin A (10), psammaplysenes D (11) and F (12), anomoian F (14), and N,N-dimethyldibromotyramine (15). Following biological tests on mammalian cells, we report here the identification of the hitherto unknown ability of the six bromotyrosine derivatives 1, 2, 5, 7, 11, and 14 of marine origin to reduce the spread of the PrP^Sc prion and the ability of compounds 1 and 2 to reduce endoplasmic reticulum stress. These two biological activities of these bromotyrosine derivatives are, to our knowledge, described here for the first time, offering a new therapeutic perspective for patients suffering from prion diseases that are presently untreatable and consequently fatal. Full article

Medical named entity recognition (NER) focuses on extracting and classifying key entities from medical texts. Through automated medical information extraction, NER can effectively improve the efficiency of electronic medical record analysis, medical literature retrieval, and intelligent medical question–answering systems, enabling doctors and researchers to obtain the required medical information more quickly and thereby helping to improve the accuracy of diagnosis and treatment decisions. The current methods have certain limitations in dealing with contextual dependencies and entity memory and fail to fully consider the contextual relevance and interactivity between entities. To address these issues, this paper proposes a Chinese medical named entity recognition model that combines contextual dependency perception and a new memory unit. The model combines the BERT pre-trained model with a new memory unit (GLMU) and a recall network (RMN). The GLMU can efficiently capture long-distance dependencies, while the RMN enhances multi-level semantic information processing. The model also incorporates fully connected layers (FC) and conditional random fields (CRF) to further optimize the performance of entity classification and sequence labeling. The experimental results show that the model achieved F1 values of 91.53% and 64.92% on the Chinese medical datasets MCSCSet and CMeEE, respectively, surpassing other related models and demonstrating significant advantages in the field of medical entity recognition. Full article

The prevalence of congenital heart disease (CHD) has surged in recent decades, owing to a substantial reduction in mortality. As individuals with CHD age, they become increasingly susceptible to late complications including arrhythmias. These arrhythmias often arise decades after surgical intervention and significantly impact quality of life, hospitalizations, and mortality. Catheter ablation has gained widespread acceptance as a critical intervention for managing arrhythmias in patients with CHD. However, anatomical and physiological features unique to this population pose challenges to standard manual ablation procedures, potentially impacting safety and efficacy. Robotic magnetic-guided navigation (RMN) has emerged as a technological solution to address these challenges. By utilizing soft and flexible catheters equipped with magnets at their tips, RMN enables robotic steering and orientation of catheters in three-dimensional space. This technology overcomes obstacles such as distorted vascular pathways and complex post-surgical reconstructions to facilitate access to target chambers and improve maneuverability within the heart. In this review, we present an overview of the safety and efficacy evidence for RMN-guided catheter ablation in CHD patients and highlight potential advantages. Additionally, we provide a detailed case presentation illustrating the practical application of RMN technology in this population. Although the literature on RMN-guided ablation in patients with CHD remains limited, it has shown promise in achieving successful outcomes, particularly in cases where manual ablation failed or was deemed non-feasible. Further validation through large-scale prospective studies is necessary to fully ascertain the benefits of RMN technology in this patient population. Full article

The specific identification of three major morphotypes of the tropical holopelagic Sargassum species causing massive strandings on the African and Caribbean coastlines was attempted by morphological characterisation as well as quantitative and qualitative analyses of several metabolites. Of the 25 morphological variables studied on 208 samples from the North Atlantic Ocean, 22 were used to establish a dichotomous identification key, allowing without any doubt the identification of each morphotype based on their morphological criteria alone. We also attempted to differentiate morphotypes using chemical fingerprintings (HR-MAS NMR) and markers by analysing pigment level and composition using High Pressure Liquid Chromatography, terpene profiles by Thin Layer Chromatography, phenolic compound levels by the Folin-Ciocalteu assay and structures by 2D Nuclear Magnetic Resonance spectroscopy, and fatty acid composition by Gas Chromatography. While pigment level and composition, terpene profiles, and phenolic contents were not discriminating, quantification of eight fatty acids enabled the differentiation of the three morphotypes. Furthermore, phlorotannin purification permitted their structural characterisation allowing discrimination between the three morphotypes. Our study highlights the potential of the free fatty acid profile and phlorotannin structure as good chemomarkers in order to discriminate between the three morphotypes of holopelagic Sargassum. Full article

Modelling sea conditions is a complex task that requires a comprehensive analysis, considering various influencing factors. Observed and unobserved factors jointly play a role in the definition of sea conditions. Here, we consider finite mixtures of generalized linear additive models for location scale, and shape (GAMLSSs) to capture the effects of both environmental variables and omitted variables, whose effects are summarized using latent variables. The GAMLSS approach is flexible enough to allow for different data features such as non-normality, skewness, heavy tails, etc., and for the definition of a regression model not only for the expected values of the observed process but also for all the other distribution parameters, e.g., the variance. We collected data on multiple sea-related and environmental variables in Ancona (Italy) from two Italian networks: the Sea Level Measurement Network (Rete Mareografica Nazionale, RMN) and the Sea Waves Measurement Network (Rete Ondametrica Nazionale, RON). Our main outcomes were the meteorological tides (often also referred to as “residuals”) and the significant wave height. Atmospheric pressure and wind speed were considered as main drivers of the sea conditions, as well as the fetch associated with wind direction, linking these variables to the outcomes through the definition of multiple linear predictors in a regression framework. Our results confirm the importance of accounting for environmental variables and reveal that their effect is heterogeneous, where heterogeneity is modelled by three distinct mixture components, each capturing different sea conditions. These findings contribute to a deeper understanding of sea state dynamics and provide evidence of a clustering structure characterizing different sea conditions. Full article