Search Results (169)

Tropical forests face increasing threats and are often replaced by secondary forests that regenerate after disturbances. In the Atlantic Forest, this creates fragments of different successional stages. The aim of this study is to understand how soil nutrients and light availability gradients influence the species composition and structure of trees and regenerating strata in remnants of lowland rainforest. We sampled 15 plots for the tree stratum (DBH ≥ 5 cm) and 45 units for the regenerating stratum (height ≥ 50 cm, DBH < 5 cm), obtaining phytosociological, entropy and equitability data for both strata. Canopy openness was assessed with hemispherical photos and soil samples were homogenized. To analyze the interactions between the vegetation of the tree layer and the environmental variables, we carried out three principal component analyses and two redundancy analyses and applied a linear model. The young fragments showed good recovery, significant species diversity, and positive successional changes, while the older ones had higher species richness and were in an advanced stage of succession. In addition, younger forests are associated with sandy, nutrient-poor soils and greater exposure to light, while mature forests have more fertile soils, display a greater diversity of dispersal strategies, are rich in soil clay, and have less light availability. Mature forests support biodiversity and regeneration better than secondary forests, highlighting the importance of preserving mature fragments and monitoring secondary ones to sustain tropical biodiversity. Full article

Habitat loss and land-use intensification are major threats to biodiversity in the Brazilian Atlantic Forest, particularly for bat assemblages that provide key ecosystem services. In this study, we examined how landscape composition (forest and pasture cover) and local forest structure influence the richness and abundance of phyllostomid bats across 20 forest fragments in southern Bahia. Bat sampling was conducted using mist nets, and forest structure was quantified using tree measurements and vertical foliage stratification. We applied structural equation modeling to test the direct and indirect effects of landscape and local variables. Our results show that forest cover has both direct and indirect positive effects on bat diversity, mediated by improved forest structure. In contrast, increased pasture cover negatively affected forest structure and was weakly associated with bat diversity. The most abundant species were generalist frugivores, such as Carollia perspicillata and Rhinophylla pumilio. These findings highlight the importance of maintaining forest cover and structural complexity to support bat diversity in agroforestry-dominated landscapes. Conservation strategies that integrate habitat protection with sustainable land-use practices are crucial to maintaining biodiversity and the ecological functions provided by bats in this globally threatened biome. Full article

Exploiting clay for brick production results in soil damage. There are no field evaluations for its recovery with organic amendments comprising biochar. We conducted a small-scale experiment to assess the recovery effects of soil using biochar, both alone and in combination with compost. On a remnant of soil from clay mining, we applied the following to plots of 2.25 m² in a randomized complete block design: (1) biochar + efficient microorganisms (EMs), (2) compost + EMs, (3) compost + biochar + EMs, and (4) a control group without amendments. Composite soil samples from each plot were collected at the beginning of the experiment and at 30, 120, and 210 days. We analyzed some physicochemical properties of the soil and recorded the number and morphotypes of seedlings. We found that biochar + EMs and biochar + compost + EMs had positive effects in the short term, particularly in reducing bulk density. No synergistic effect was observed between biochar and compost, contrary to what was expected, which may be due to the short term of the experiment and prevailing low temperatures. The compost + EM treatment resulted in greater seedling diversity. In conclusion, bulk density can be used as an early indicator of soil improvement when biochar alone or combined with compost is used. Biochar may be a striking solution for promoting sustainable soil management after clay mining in high-elevation conditions. Full article

Galactic cosmic rays (GCRs), composed of protons and atomic nuclei, are accelerated in sources such as supernova remnants and pulsar wind nebulae, reaching energies up to the PeV range. As they propagate through the interstellar medium, their interactions with dense regions like molecular clouds produce secondary particles, including gamma-rays and neutrinos. In this study, we use the Geant4 Monte Carlo toolkit to simulate secondary particle production from GCR interactions within the Perseus molecular cloud, a nearby star-forming region. Our model incorporates realistic cloud composition, a wide range of incidence angles, and both hadronic and electromagnetic processes across a broad energy spectrum. The results highlight molecular clouds as significant sites of multi-messenger emissions and contribute to understanding the propagation of GCRs and the origin of diffuse gamma-ray and neutrino backgrounds in the Galaxy. Full article

Objective: This in vitro study evaluated the effectiveness of three laser systems—diode, CO₂, and Er:YAG—for debonding composite attachments used in aligner orthodontic therapy. Materials and Methods: Fifty extracted human premolars with composite attachments were divided into five groups (n = 10): control, RT (rotary tools), diode laser (980 nm, irradiance was 4811 W/cm²), CO₂ laser (10.6 µm, irradiance 1531 W/cm²), and Er:YAG laser (2940 nm, irradiance 471.7 W/cm²). Shear bond strength (SBS) testing measured debonding forces. Enamel surface changes were evaluated using micro-CT, optical profilometry, and stereomicroscopy. The Adhesive Remnant Index (ARI) assessed residual bonding material. Results: Laser treatment increased enamel roughness (p < 0.05). Er:YAG laser caused the highest roughness (Sa = 2.03 µm) and up to 0.17 mm enamel loss but left minimal adhesive remnants and no fractures. Diode laser preserved surface smoothness with moderate bond weakening. CO₂ laser had intermediate effects. RT showed the highest SBS but resulted in greater enamel alteration. SBS was significantly reduced in the laser groups, lowest for Er:YAG (81.7 ± 45.5 MPa vs. control 196.2 ± 75.3 MPa). ARI indicated better adhesive removal in the laser-treated groups, with Er:YAG showing the highest percentage of clean enamel surfaces (67% vs. 25%). Conclusions: Er:YAG demonstrated the best balance between effective debonding and enamel preservation. Diode and CO₂ lasers also offer viable alternatives to rotary tools. Further clinical studies are recommended. Full article

BiFeO₃ is a fascinating material with a rhombohedral crystal structure (R3c) at room temperature. This unique structure makes it suitable for use in solar cells, as the interaction of light with the polarized octahedral enhances electron movement. Evaluating its properties on different substrates helps to identify the specific characteristics of thin films. The thin films presented in this work were deposited using reactive RF cathodic sputtering with a homemade 1-inch diameter ceramic target. Their morphology, phase composition, optical, piezoelectric, and ferroelectric properties were evaluated. Fluorine Tin Oxide (FTO) and Indium Tin Oxide (ITO) substrates were used for the presented thin films. The thin films deposited on FTO displayed the “butterfly” behavior typically associated with ferroelectric materials. A d₃₃ value of 2.71 nm/V was determined using SSPFM-DART mode. In contrast, the thin films deposited on ITO at 550 °C reached a maximum saturation polarization of 40.89 μC/cm² and a remnant polarization of 44.87 μC/cm², which are the highest values recorded, but did not present the typical “butterfly” behavior. As the grain size increased, the influence of charge defects became more pronounced, leading to an increase in the leakage current. Furthermore, the presence of secondary phases also contributed to this behavior. Full article

Composites of ferromagnetic and ferroelectric phases are of interest for studies on mechanical strain-mediated coupling between the two phases and for a variety of applications in sensors, energy harvesting, and high-frequency devices. Nanocomposites are of particular importance since their surface area-to-volume ratio, a key factor that determines the strength of magneto-electric (ME) coupling, is much higher than for bulk or thin-film composites. Core–shell nano- and microcomposites of the ferroic phases are the preferred structures, since they are free of any clamping due to substrates that are present in nanobilayers or nanopillars on a substrate. This review concerns recent efforts on ME coupling in coaxial fibers of spinel or hexagonal ferrites for the magnetic phase and PZT or barium titanate for the ferroelectric phase. Several recent studies on the synthesis and ME measurements of fibers with nickel ferrite, nickel zinc ferrite, or cobalt ferrite for the spinel ferrite and M-, Y-, and W-types for the hexagonal ferrites were considered. Fibers synthesized by electrospinning were found to be free of impurity phases and had uniform core and shell structures. Piezo force microscopy (PFM) and scanning microwave microscopy (SMM) measurements of strengths of direct and converse ME effects on individual fibers showed evidence for strong coupling. Results of low-frequency ME voltage coefficient and magneto-dielectric effects on 2D and 3D films of the fibers assembled in a magnetic field, however, were indicative of ME couplings that were weaker than in bulk or thick-film composites. A strong ME interaction was only evident from data on magnetic field-induced variations in the remnant ferroelectric polarization in the discs of the fibers. Follow-up efforts aimed at further enhancement in the strengths of ME coupling in core–shell composites are also discussed in this review. Full article

The transition zone between a shallow-water delta and tidal flat is characterized by a high degree of mixed siliciclastic–carbonate sedimentation. There are frequent lateral and vertical variations in sandstone, dolostone, limestone, and mixed siliciclastic–carbonate rock (MSR); however, their influence on reservoir quality remains uncertain. Member B of the Asmari Formation (Asmari B) in Iraq’s C Oilfield was deposited in a remnant ocean basin formed by the closure of the Neo-Tethys Ocean. During the Oligocene–Miocene, frequent exposure of the Arabian Shield provided intermittent sediment sources to the study area. Under shallow water and relatively arid conditions, widespread mixed sedimentation of siliciclastic sand and dolomitic components occurred. Taking Asmari B as a case study, this research employs core and thin-section observations, trace element analyses, and quantitative mineralogical interpretations of logging data to investigate the characteristics of mixed sedimentation and to evaluate its impact on reservoir quality. Four key aspects were identified: (1) Four main types of mixed lithofacies developed in Member B of the Asmari Formation, namely sandstone-bearing dolomite, dolomitic sandstone, dolostone-bearing sand, and sandy dolostone. These lithofacies were deposited in the transition zone between distributary channels and intertidal zone with different water depths. As the terrigenous input decreased, the water depth for sand-bearing facies increased. In particular, sandy dolostone was predominantly formed in subtidal settings under the influence of storm events. (2) MSRs are categorized based on the proportion of the minor component into high and low mixing degrees. Based on mineral compositions interpreted from well logging data, the mixing degree of MSRs was characterized by the thickness ratio, using the thickness of high- and low-mixing-degree MSRs relative to the total thickness of the formation. The MSRs mainly developed in the B1, B2, B3-1, B3-2, and B4 sublayers, where moderate provenance supply facilitated the high mixing of terrigenous clastic and carbonate components. (3) The pore and throat patterns of MSR reservoirs change with the mixing degree index. When the dolomite content in sandstone exceeds 25%, the pore–throat structure changes significantly. A small amount of sand in dolostone has little effect on the pore and throat. Sandy dolostone exhibits the poorest reservoir quality. (4) Mixed sandstone reservoirs are distributed on both sides of the distributary channels and mouth bar. The dolostone-bearing sand reservoirs are distributed in the transition zone between the sandy flat and dolomite flat. Sandy dolostone is mainly thin and isolated due to the influence of storm events. This study provides guidance for understanding the development patterns of MSR reservoirs under similar geological settings, facilitating the next step of oil and gas exploration in these special reservoirs. Full article

Molecular network conformations in the over-stoichiometric arsenoselenides of canonical As_xSe_100−x system (40 ≤ x ≤ 100) covering a full row of thioarsenide-type As₄Se_n entities (0 ≤ n ≤ 6) are analyzed with ab initio quantum-chemical modeling employing cluster-simulation code CINCA. Native (melt-quenching-derived) and nanostructurization-driven (activated by nanomilling) polymorphic and polyamorphic transitions initiated by decomposition of the thioarsenide-type As₄Se_n cage molecules and incorporation of their remnants into a newly polymerized arsenoselenide network are identified on the developed map of molecular network clustering in a binary As-Se system. Within this map, compositional counter lines corresponding to preferential molecular or network-forming tendencies in the examined arsenoselenides are determined, explaining that network-crystalline conformations prevail in the boundary compositions corresponding to n = 6 and n = 0, while molecular-crystalline ones dominate inside the rows corresponding to n = 4 and n = 3. A set of primary and secondary equilibrium lines is introduced in the developed clustering map to account for inter-phase equilibria between the most favorable (regular) and competitive (irregular) thioarsenide phases. Straightforward interpretation of decomposition reactions accompanying induced crystallization and amorphization (reamorphization) in the arsenoselenides is achieved, employing disproportionality analysis of thioarsenide-type molecular network conformations within the reconstructed clustering map. The preference of network clustering at the boundaries of the As₄Se_n row (at n = 6 and n = 0) disturbs inter-phase equilibria inside this row, leading to unexpected anomalies, such as absence of stable tetra-arsenic triselenide As₄Se₅ molecular-crystalline species; polyamorphism in mechanoactivated As₄Se_n alloys (2 ≤ n ≤ 6); breakdown in the glass-forming ability of melt-quenching-derived arsenoselenides in the vicinity of tetra-arsenic biselenide As₄Se₂ composition; plastically and normally crystalline polymorphism in tetra-arsenic triselenide As₄Se₃-based thioarsenides, and so on. Full article

The complex interaction of hydrothermal fluids and carbonate rocks is recognized to promote significant impacts on petroleum systems, reservoir porosity, and potential. The objective of this study is to investigate the fluid phases entrapped in the mineral phases of the Barra Velha Formation (Santos Basin), including their petrographic paragenetic relationships, relative timing, temperatures of migration events, and maximum temperature reached by the sedimentary section. The petrographic descriptions (387), Rock-Eval pyrolysis (107), fluid inclusion petrography (14), and microthermometry (428) were performed on core and sidewall samples from two wells from one field of the Santos Basin. Hydrocarbon source intervals were primarily identified in lithologies with high argillaceous content. Chert samples still retain some organic remnants indicative of their original composition prior to extensive silicification. Redeposited intraclastic rocks exhibit the lowest organic content and oil potential. A hydrothermal petroleum system is identified by fluids consisting in gas condensate, light to heavy undersaturated oil, occasionally accompanied by aqueous fluids influenced by juvenile and evaporitic sources, and localized flash vaporization events. These hydrothermal fluids promoted silicification and dolomitization, intense brecciation, and lead to enhanced porosity in different compartments of the reservoir. The relative ordering of paleo-hydrothermal oils and the main oil migration and accumulation events has improved our understanding of the petroleum systems in the basin. This contribution is significant for future regional research on the evolution of fluid systems and their implications for carbonate reservoirs. Full article

The excellent temperature stability and high saturation polarization of Bi_0.5Na_0.5TiO₃ (BNT) make it a promising candidate for energy storage capacitors. However, its disadvantages, such as low breakdown strength, high remnant polarization, and a complex sintering process, limit its further development. To address this, (1 − x) Bi_0.5Na_0.5TiO₃−x Sr(Mg_1/3Nb_2/3)O₃ ceramics were fabricated, where ion doping was employed to modify the domain structure, reduce the grain size, and improve the energy storage performance. With the increase in dopant concentration, the evolution from long-range-ordered ferroelectric micro-domains into short-range-ordered randomly oriented polar nanoregions (PNRs) was revealed, as demonstrated by XRD and Raman spectroscopy. This resulted in a diffuse phase transition peak and a significant reduction in remnant polarization. However, the saturation polarization also decreased. Finally, the optimal energy storage performance was achieved at a medium dopant concentration (x = 0.10), accompanied by reduced grain size and a dense microstructure. This composition exhibited a discharged energy density of 1.64 J/cm³ at a low electric field of 150 kV/cm, representing a notable improvement over pure BNT, which showed a highly lossy P-E loop and a discharged energy density of only 0.14 J/cm³ at the same electric field. Full article

Different treatments have been proposed for morphofunctional bone repair; however, they are not always efficient and have limitations. In this experimental study, we present matrix composites with a possible synergistic effect acting with scaffolds for bone growth and use of photobiomodulation (PBM) to accelerate this tissue repair. Thus, the objective was to evaluate the effect of PBM in the repair of a long bone (tibia) of rats filled with biomimetic collagen matrices with nanohydroxyapatite and heterologous fibrin biopolymer (FB). Forty-eight rats were distributed into eight groups (n = six each): Blood Clot (BC), Blood Clot + PBM (BCP), Matrix (M), Matrix + PBM (MP), Fibrin Biopolymer (FB), Fibrin Biopolymer + PBM (FBP), Matrix + FB (MFB), Matrix + FB + PBM (MFBP). A 2.0 mm bone defect was created in the proximal third of the left tibia. The BCP, MP, FBP, and MFBP groups underwent PBM during surgery and maintained twice a week until euthanasia at 42 days. Microcomputed tomography (micro-CT), histomorphological and histomorphometric analyses were performed. Micro-CT analysis revealed that PBM influenced cortical interposition between the remnant and newly formed bone. Histologically, no exacerbated inflammatory focus or foreign body-type granulomatous reaction was observed in any group; however, a vast collagenous matrix with a more oriented and thicker spatial conformation was observed in the PBM-treated groups. Histomorphometrically, the BCP, MP, and MFBP groups showed significantly higher values compared to the other groups. Specifically, the BC group presented a mean bone tissue density of 68.33 ± 7.394, while the BCP and MP groups showed 99.83 ± 11.87 and 99.67 ± 20.58, respectively (p < 0.05). Qualitative analysis of collagen fibers indicated enhanced organization and maturation in PBM-treated groups. This study concluded that the association of PBM in the repair of long bones in rats, filled with biomimetic collagen matrices with nanohydroxyapatite and fibrin biopolymer, presented results that contribute to the improvement of bone growth, together with the association of scaffolds. Full article

We present the evidence of high-velocity regions within the Pacific Large Low Seismic Velocity Province (LLSVP), uncovered using the Virtual Receiver Approach (VRA), a novel seismic imaging method that allows us to determine local absolute velocity values of a non-reflecting body wave that are independent of any assumed Earth model. Our results reveal a complex dynamics of high- and low-velocity regions within the Pacific LLSVP. While low-shear-wave velocities dominate, consistent with the traditionally understood nature of LLSVPs, we identify distinct high-velocity anomalies—an observation not previously reported in this region. We interpret these anomalies as lateral compositional variations within the LLSVP. Petrological modeling suggests that high-velocity regions are associated with low FeO content, potentially linked to the inclusion of post-perovskite material driven by mantle convection. Alternatively, remnants of subducted oceanic crust (e.g., Mid-Ocean Ridge Basalts) could also explain the observed features. Conversely, low-velocity anomalies correspond to FeO-rich compositions. Our findings highlight the thermochemical heterogeneity of the LLSVP, revealing a more complex internal structure than previously thought. The application of the VRA is able to resolve fine-scale structures that have remained as some of the biggest challenges in global tomographic models. Full article

Neutrophil extracellular traps (NETs) are web-like structures composed of chromatin and proteins from neutrophil granules. Several studies highlight the heterogeneity of NETs, underscoring the challenges associated with their detection. In patients with COVID-19, high levels of NET fragments, called NET remnants, are detected in the circulation but also in alveoli and bronchioles. NET remnants are usually measured as complexes of DNA and myeloperoxidase (DNA−MPO). Taking advantage of proteomic data on NET composition, we developed new solid-phase assays to detect NET remnants, measuring complexes of DNA with alpha enolase (DNA−eno) or calprotectin (DNA−cal). The two assays were compared with the DNA−MPO test for the detection of in vitro-generated NET and serum NET remnants; all of them showed similar sensitivity in the detection of in vitro-generated NET. In an analysis of 40 patients with severe COVID-19 and 25 healthy subjects, the results of the three assays were highly correlated, and all detected significantly higher levels of NET remnants in patient sera. Moreover, the level of NET remnants correlated with impaired gas exchange and increased with the progressive decline of pulmonary function. The proposed assays thus represent a novel tool with which to evaluate NETosis; using antibodies to different NET constituents may allow their fingerprinting in different disorders. Full article

Patient demands for aesthetic orthodontic brackets (OBs) has increased since orthodontic treatments are of long duration. Clinicians encounter old composite restorations frequently, against which OBs need to be bonded. This study aims to determine the shear bond strength (SBS) of two aesthetic OBs (ceramic and resin) against aged composite resins (flowable and packable) after standard surface treatment. A total of 96 disk-shaped specimens of two aged (A) composite resins [flowable (F) and packable (P)] were divided into eight groups, using ceramic (C) and plastic (P) brackets, out of which four subgroups served as the control [non-aged (N)FC, NPC, NFR, NPR] and four as experimental [AFC, APC, AFR, APR]. Surface treatment included mechanical [air abrasion] and chemical [Assure Plus and Transbond XT]. After 24 h of storage, the specimens were tested for SBS and observed for failure mode using adhesive remnant index scores. Mean values of SBS in each subgroup were analyzed statistically using a one-way analysis of variance test and Tukey post hoc test. All probability ‘p’ differences were significant at a value of 0.05 and less. All aged composite resin subgroups had decreased bond strength than controls, with all subgroups bonded with plastic brackets having the least bond strengths that were clinically nonacceptable [≤7 to 10 MPa]. Flowable composites when bonded with either ceramic or plastic brackets had higher strength than packable composites. Ceramic brackets had higher SBS than plastic brackets for both flowable and packable composites. Significant differences in bond strength were observed among subgroups of plastic brackets. Ceramic brackets were associated with a higher residue of adhesives on the composite surface. Aged composite resins exhibit significantly lower SBS than fresh composites, with ceramic brackets and flowable composites producing better bond strength values than plastic brackets and packable composites. Full article