Search Results (94)

Background and Objectives: Peri-implantitis is a biologically driven complication that jeopardizes dental implant longevity. While chemical decontamination is frequently employed as an adjunct to mechanical debridement, its impact on implant surface integrity and cellular compatibility remains insufficiently defined. This study aimed to evaluate the effects of several chemical agents used in peri-implantitis treatment on the surface morphology and potential biocompatibility of titanium dental implants. Materials and Methods: Twenty-five Ti6Al4V implants were exposed to one of the following agents: saline solution, 3% hydrogen peroxide, 40% citric acid, 17% EDTA, and a mixture (1:1) of citric (2%) and phosphoric (1N) acids. This in vitro study employed a 7-day immersion protocol to accentuate surface effects under controlled laboratory conditions, acknowledging that clinical exposures are substantially shorter. Surface topography was evaluated by Atomic Force Microscopy, while cellular response and corrosion products were assessed using Scanning Electron Microscopy. Surface roughness parameters were statistically analyzed. Results: Hydrogen peroxide induced selective corrosion of the β phase and formed a compact passivation layer that supported mesenchymal stem cell adhesion. Citric acid etched grain boundaries, producing localized roughness that also permitted cell proliferation. EDTA caused advanced grain dissolution and debris accumulation, increasing surface roughness but impairing cellular adhesion. The citric–phosphoric acid mixture led to the highest roughness values and visible corrosion debris. In all cases, macrostructural integrity of the implants was preserved. Conclusions: Chemical agents used in peri-implantitis treatment induce distinct surface alterations on titanium implants. Controlled use of hydrogen peroxide and citric acid may enhance surface biocompatibility, while aggressive protocols such as EDTA and acid combinations require caution due to their adverse effects on surface morphology and cellular response. These findings may inform the development of optimized decontamination protocols for clinical management of peri-implantitis. Full article

This comprehensive review compiles current knowledge about the connection between plastic waste and the selection and transmission of antibiotic resistance genes (ARGs) in aquatic ecosystems, which can result in ARG contamination of fishery products—a significant source of microplastic (MP) introduction into the food chain. Plastic debris in aquatic environments is covered by a biofilm (the plastisphere) in which antibiotic-resistant bacteria (ARB) are selected and horizontal gene transfer (HGT) of ARGs is facilitated. The types of plastic waste considered in this study for their role in ARG enrichment are mainly microplastics (MPs), and also nanoplastics (NPs) and macroplastics. Studies regarding freshwaters, seawaters, aquaculture farms, and ARG accumulation favored by MPs in aquatic animals were considered. Most studies focused on the identification of the microbiota and its correlation with ARGs in plastic biofilms, while a few evaluated the effect of MPs on ARG selection in aquatic animals. A higher abundance of ARGs in the plastisphere than in the surrounding water or natural solid substrates such as sand, rocks, and wood was repeatedly reported. Studies regarding aquatic animals showed that MPs alone, or in association with antibiotics, favored the increase in ARGs in exposed organisms, with the risk of their introduction into the food chain. Therefore, reducing plastic pollution in water bodies and aquaculture waters could mitigate the ARG threat. Further investigations focused on ARG selection in aquatic animals should be conducted to better assess health risks and increase awareness of this ARG transmission route, enabling the adoption of appropriate countermeasures. Full article

Gasoline is the most common ignitable liquid used to initiate fires, making its detection and identification in fire debris crucial for determining incendiary origins. Fire debris is typically collected after extinguishment and safety clearance, often resulting in gasoline weathering, especially when delayed. Most research on gasoline weathering has been conducted in controlled laboratory settings in temperate climates. However, the effects of tropical conditions on the rate of gasoline weathering and the resulting chemical composition of volatiles remain largely unexplored. Understanding how tropical environmental factors alter gasoline weathering is essential for accurate fire debris interpretation in such regions. This study investigates how tropical climates impact gasoline weathering indoors and outdoors. Weathered samples were prepared by volume reduction method, gradually evaporating gasoline from 10% to 95%. Indoor samples were exposed to room temperature, while outdoor samples were left in open space under natural tropical conditions. Gas Chromatography/Mass Spectrometry (GC-MS) analysis revealed chromatographic shifts in heavier compounds (C₃–C₄ alkylbenzenes) compared to lighter ones like toluene as weathering progressed. Correlation between indoor and outdoor samples was high (>0.970) at 10–50% weathering but declined (<0.600) at 90–95%, indicating differing patterns. All target compounds remained detectable across all samples. Full article

The DD Guyot, a flat-topped seamount located in the Western Pacific, was completely mapped using multibeam echosounders (MBESs) in 2024. Clarifying substratum patterns is crucial for understanding seafloor evolution, sediment transport processes, and resource assessment. This study integrates near-bottom video data from the manned submersible Jiaolong, multibeam bathymetry and backscatter data from EM124, and a convolutional neural network (CNN) model to classify the four substratum types (exposed bedrock, thinly sedimented bedrock, sediment–rock transition zone, and continuous sediment) of the DD Guyot. The results indicate that exposed bedrock predominates on the summit platform, while sediment cover increases with water depth along the flank. The base of the guyot is almost entirely covered by sediments. Two landslide areas were identified, with clear main scarps, sidewalls, and debris accumulations. These features, together with underflow erosion, collectively influence sediment distribution patterns. The resulting substratum maps provide guidance for seabed resource exploration. The results are consistent with a post-drowning onlap framework, which points to a drowning unconformity, but video and surface acoustic data alone are insufficient for definitive confirmation. Further investigation is required to more clearly elucidate the substratum characteristics of the DD Guyot. Full article

This study investigates the effect of hydrogen charging time on the mechanical properties and microstructural evolution of low-carbon ferrite–pearlite steel that has been in service for over 30 years in natural gas transmission. Specimens were subjected to in-situ electrochemical hydrogen charging for varying durations, followed by tensile testing. Detailed microstructural analysis was performed using scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Despite negligible changes in the overall hydrogen content ($C_H$≈ 4.0 wppm), significant alterations in fracture morphology were observed. Fractographic and TEM analyses revealed a clear transition from ductile fracture in uncharged specimens to a predominance of brittle fracture modes (quasi-cleavage, intergranular, and transgranular) in hydrogen-charged samples. The results show time-dependent microstructural changes, including increased dislocation density and the formation of prismatic loop debris, particularly within the ferrite phase. Prolonged charging leads to localized embrittlement, which is explained by enhanced hydrogen trapping at ferrite-cementite boundaries, grain boundaries, and dislocation cores. TEM investigations further indicated a sequential activation of hydrogen embrittlement mechanisms: initially, Hydrogen-Enhanced Localized Plasticity (HELP) dominates within ferrite grains, followed by Hydrogen-Enhanced Decohesion (HEDE), particularly at ferrite-cementite interfaces in pearlite colonies. These findings demonstrate that extended hydrogen charging promotes defect localization, dislocation pinning, and interface decohesion, ultimately accelerating fracture propagation. The study provides valuable insight into the degradation mechanisms of ferrite-pearlite steels exposed to hydrogen, highlighting the importance of charging time. The results are essential for assessing the reliability of legacy pipeline steels and guiding their safe use in future hydrogen transport infrastructure. Full article

Glacier retreat due to climate change is accelerating worldwide, yet the phenomenon remains abstract for many people, especially those unfamiliar with mountain environments. The Urban Glaciology experiment, conducted during Milan’s internationally renowned “Fuorisalone” 2024 design event, aimed to bridge this perceptual gap by simulating real glacier melt processes in a busy urban square. Three large ice blocks with contrasting surface conditions (i.e., clean, dirty, and debris-covered) were exposed to springtime urban temperatures, mimicking conditions found on Alpine glaciers during summer. Over one week, the blocks produced a total of 748 L of meltwater, with dirty ice melting up to four times faster than debris-covered ice, consistent with established albedo effects. These results confirmed the thermal analogy between Milan’s spring conditions (+15 to +20 °C) and the ablation season on Alpine glaciers. Visitors observed the differential melting in real time, supported by visual indicators, explanatory panels, immersive virtual experiences, and direct interaction with researchers and students. Informal interviews indicated that more than 60% of participants reported a perceptual shift, recognizing for the first time that urban temperatures can replicate glacier melting conditions. By embedding a science-based installation in a major cultural tourism event, the experiment reached a diverse, non-traditional audience—including tourists, designers, and citizens—and encouraged reflection on the implications of glacier loss. The success of this initiative highlights the potential of replicating similar models in other cities to raise awareness of environmental change through culturally engaging experiences. Full article

High-density polyethylene (HDPE) is widely used for different applications, but its low resistance to ultraviolet radiation, plastic deformation, chemical stability, and wear re-sistance limits its use in high-demand work environments. Modifying of the surface characteristics could improve the work efficiency of the parts exposed to an aggressive environment. Plasma treatments change the surface characteristics with deposition of a coating or by modifying the surface’s energy, varying the surface properties. This study presents the mechanical and tribological properties of a titanium (Ti) layer with fiber-like morphology produced on HDPE surfaces by plasma treatment involving plasma etching and the deposition of Ti atoms, through DC magnetron sputtering. On the HDPE substrates grew up Ti layer with fibers-like morphology with a diameter of 1.6 ± 0.44 μm. These fibers were elemental composed by 91.5 ± 0.9% Ti and 8.5 ± 0.6% O with α-Ti phase combined with HDPE crystalline structure. The Ti coating increased the hardness of the substrate and showed a good adhesion to HDPE surface. During the sliding test, the Ti layer with fiber-like morphology exhibited plastic deformation and debris accumulation, leading to the formation of a tribolayer without layer detachment. Notably, no detachment of the layer was observed, effectively protected the polymer surface, and enhanced its performance for tribological applications. Full article

Plastic debris is a pervasive and persistent threat to marine ecosystems. Microplastics (plastics < 5 mm) are increasing in a variety of marine habitats, including open water systems, shorelines, and benthic sediments. It remains unclear how microplastics distribute and accumulate in marine systems and the extent to which this pollutant is accessible to marine taxa. We examined subtidal benthic sediments and beach sediments in critical nearshore habitats for forage fish species—Pacific sand lance (Ammodytes personatus), Pacific herring (Clupea pallasi), and surf smelt (Hypomesus pretiosus)—to quantify microplastic concentrations in the spawning and deep-water habitats of these fish and better understand how microplastics accumulate and distribute in nearshore systems. In the San Juan Islands, we examined an offshore subtidal bedform in a high-flow channel and beach sites of protected and exposed shorelines. We also examined 12 beach sites proximate to urban areas in Puget Sound. Microplastics were found in all samples and at all sample sites. Microfibers were the most abundant, and flakes were present proximate to major shipyards and marinas. Microplastics were significantly elevated in Puget Sound compared to the San Juan Archipelago. Protected beaches had elevated concentrations relative to exposed beaches and subtidal sediments. Microplastics were in higher concentrations in sand and fine-grain sediments, poorly sorted sediments, and artificial sediments. Microplastics were also elevated at sites confirmed as spawning habitats for forage fish. The model results indicate that both current speed and proximate urban populations influence nearshore microplastic concentrations. Our research provides new insights into how microplastics are distributed, deposited, and retained in marine sediments and shorelines, as well as insight into potential exposure in benthic, demersal, and shoreline habitats. Further analyses are required to examine the relative influence of urban populations and shipping lanes and the effects of physical processes such as wave exposure, tidal currents, and shoreline geometry. Full article

Morphological problems for distinguishing between glacier ice, glacier ice with a debris cover (debris-covered glaciers), and rock glaciers are outlined with respect to recognising and mapping these features. Decimal latitude–longitude [dLL] values are used for geolocation. One model for rock glacier formation and flow discusses the idea that they consist of ‘mountain permafrost’. However, signs of permafrost-derived ice, such as flow features, have not been identified in these landsystems; talus slopes in the neighbourhoods of glaciers and rock glaciers. An alternative view, whereby rock glaciers are derived from glacier ice rather than permafrost, is demonstrated with examples from various locations in the mountain domain, 𝔻𝕞. A Google Earth and field examination of many rock glaciers shows glacier ice exposed below a rock debris mantle. Ice exposure sites provide ground truth for observations and interpretations stating that rock glaciers are indeed formed from glacier ice. Exposure sites include bare ice at the headwalls of cirques and above debris-covered glaciers; additionally, ice cliffs on the sides of meltwater pools are visible at various locations along the lengths of rock glaciers. Inspection using Google Earth shows that these pools can be traced downslope and their sizes can be monitored between images. Meltwater pools occur in rock glaciers that have been previously identified in inventories as being indictive of permafrost in the mountain domain. Glaciers with a thick rock debris cover exhibit ‘hidden ice’ and are shown to be geomorphological units mapped as rock glaciers. Full article

Vulvar hygiene is an important part of general hygiene: the goals are to clear the vulvar area of microbial and cellular debris and vaginal and fecal secretions, ensure local comfort, provide natural levels of hydration, and protect the vulvar microbiota. There are few national and international guidelines on vulvar hygiene. We searched the PubMed database up until 30 November 2024, using logical combinations of the following terms: hygiene, washing, vulva, vulvar, microbiota, hydration, syndet, soap, detergent, water, and customs. The abstracts were reviewed, and potentially relevant full-text articles were retrieved and examined. The subregions of the vulva vary with regard to the presence of sweat and sebaceous glands, the keratin content, the water content, the pH, and the microbiota (notably Lactobacillus, Corynebacterium, Staphylococcus, and Prevotella). An alteration in the vulvar microbiota can cause an imbalance in the vaginal microbiota, and vice versa. Vaginal douching may have negative effects on vulvar microbiota. Hair removal might increase the risk of long-term dermatological complications. Repeated washing with water alone exposes the stratum corneum to damage, and washing with soap alters the stratum corneum proteins and lipids, increases skin water loss, and accentuates the risk of irritation. Syndet-based products have a mild detergent effect, promotion of hydration, a suitable pH for the vulvar area, and protection of the vulvar microbiota. Syndet-based products (containing a blend of surfactants, emollients, antioxidants, and buffering agents) appear to be the most appropriate for vulvar care. Full article

This study presents the optimization of a laser ablation process designed to achieve the precise removal of polyamide coatings from ultra-thin platinum wires. Removing polymer coatings is a critical challenge in high-reliability manufacturing processes such as aerospace thermocouple fabrication. The ablation process must not only ensure the complete removal of the polyamide insulation but also maintain the tensile strength of the wire to withstand mechanical handling in subsequent manufacturing stages. Additionally, the exposed platinum surface must exhibit low surface roughness to enable effective soldering and be free of thermal damage or residual debris to pass strict visual inspections. The wires have a total diameter of 65 µm, consisting of a 50 µm platinum core encased in a 15 µm polyamide coating. By utilizing a UV laser with a wavelength of 355 nm, average power of 3 W, a repetition rate range of 20 to 200 kHz, and a high-speed marking system, the process parameters were systematically refined. Initial attempts to perform the ablation in an air medium were unsuccessful due to inadequate thermal control and incomplete removal of the polyamide coating. Hence, a water-assisted ablation technique was explored to address these limitations. Experimental results demonstrated that a scanning speed of 1200 mm/s, coupled with a line spacing of 1 µm and a single ablation pass, resulted in complete coating removal while ensuring the integrity of the platinum substrate. The incorporation of a water layer above the ablation region was considered crucial for effective heat dissipation, preventing substrate overheating and ensuring uniform ablation. The laser’s spot diameter of 20 µm in air and a focal length of 130 mm introduced challenges related to overlap control between successive passes, requiring precise calibration to maintain consistency in coating removal. This research demonstrates the feasibility and reliability of water-assisted laser ablation as a method for a high-precision, non-contact coating material. Full article

Microplastics (MPs) are emerging pollutants that are ubiquitous in aquatic ecosystems and can affect the stability of aquatic food webs. They are intentionally produced in a size of less than 5 mm for specific purposes or are the result of the fragmentation of larger plastic debris. Zooplankton can be affected directly by the ingestion of MPs or indirectly by interference caused by suspended plastic particles. Various environmental agencies recommend the genus Moina for assessing risk from water pollutants. However, this genus has received less attention in research compared to non-indigenous cladocerans commonly used as test organisms. We evaluated the effects of artificially fragmented acrylonitrile butadiene styrene microplastics (ABS-MPs) on key demographic parameters such as survival, mortality, life expectancy, fecundity, and feeding rates of Moina macrocopa americana. We exposed M. macrocopa neonates to a diet consisting of the green microalgae Chlorella vulgaris and ABS-MP particles. Four treatments were set with different concentrations of ABS-MP particles (5, 10, and 20 mg L⁻¹). Survivorship, mortality, and reproduction were recorded daily until the last individual from the original cohort died. ABS-MPs significantly reduced M. macrocopa consumption rates of C. vulgaris, with an 85% decrease compared to the control. Although no statistically significant differences were found in life expectancy, net reproduction, or generation time among the toxic treatments, these parameters were drastically reduced compared to the control, even at the lowest concentration (5 mg L⁻¹); this resulted in a 34% reduction in average lifespan. The ABS-MPs interfere with the long-term population dynamics of M. macrocopa and change their consumption rates, potentially decreasing their fitness. Full article

Brake wear emissions can be reduced by altering the surface of brake disks. A parametric study using a gray cast iron and a laser-cladded brake disk was performed in a pin-on-disk experiment with integrated optical pin surface characterization and particle emission measurement. Significant differences in the friction, wear and emission behavior are present. The high wear-resistance of the laser-cladded disk led to a reduction of 70% of the particle number emission relative to the gray cast iron disk, but the coefficient of friction was unstable. The surface of the pin used with the gray cast iron showed an initial large debris extension and protruding patches that were removed at high braking energies, exposing white patches and creating holes. These observations correspond to known processes from the plateau theory. The surface of the pin used with the laser-cladded disk showed a topography dominated by holes with almost no protruding patches. The braking condition did not influence the pin surface, implying that the disk and not solely the pin surface might be governing the friction process, and therefore challenging the applicability of the plateau theory to laser-cladded disks. To further study this aspect, a segmentation method was developed for the pin surface images and topographical data to extract and quantify different features on the pin, such as debris, patches, holes and the tribolayer. The correlation of the surface coverage ratios of the feature classes with the braking conditions (speed and applied pressure), the coefficient of friction and the emissions confirmed the differences between the gray cast iron and laser-cladded brake disk. Full article

When rivers impinge on the steep bluffs of valley walls, dynamic changes stem from a combination of fluvial and mass wasting processes. This study identifies the geomorphic changes, drivers, and timing of a landslide adjacent to the Apalachicola River at Alum Bluff, the tallest natural geological exposure in Florida at ~40 m, comprising horizontal sediments of mixed lithology. We used hydrographic surveys from 1960 and 2010, two sets of LiDAR from 2007 and 2018, historical aerial, drone, and ground photography, and satellite imagery to interpret changes at this bluff and river bottom. Evidence of slope failure includes a recessed upper section with concave scarps and debris fans in the lower section with subaqueous features including two occlusions and a small island exposed from the channel bottom at lower water levels. Aerial photos and satellite images indicate that the failure occurred in at least two phases in early 2013 and 2015. The loss in volume in the 11-year interval, dominantly from the upper portion of the bluff, was ~72,750 m³ and was offset by gains of ~14,760 m³ at the lower portion of the bluff, suggesting that nearly 80% of the material traveled into the river, causing changes in riverbed morphology from the runout. Despite being along a cutbank and next to the scour pool of a large meandering river, this failure was not driven by floods and the associated lateral erosion, but instead by rainfall in noncohesive sediments at the upper portion of the bluff. This medium-magnitude landslide is now the second documented landslide in Florida. Full article

Debris flows are one of the most common and frequent natural hazards in mountainous environments. For this reason, there is a need to develop monitoring systems aimed at better understanding the initiation and propagation mechanisms of these phenomena to subsequently adopt the most reliable mitigation measures to safeguard anthropic assets and human lives exposed to the impact of debris flows in alluvial fan areas. However, the design of a responsive monitoring system cannot overlook the need for a thorough understanding of the catchment in which debris flows occur. This knowledge is essential for making optimized decisions regarding the type and number of sensors to include in the monitoring system and ensuring their accurate and efficient placement. In this paper, it is described how the preliminary characterization of an Alpine catchment and the geo-hydrological processes that have historically affected it—such as the lithological and geomechanical classification of the catchment’s bedrock, the identification and description of sediment source areas, the characterization of debris flow occurrence and quantification of the triggering causes—contribute to the optimal design of a monitoring system. Additionally, the data recorded from the sensors during a debris flow event in summer 2024 validate and confirm the results obtained from previous research. Full article