Search Results (301)

When exposed to high contact pressure and shear conditions, the sliding and/or rolling contact interfaces of moving mechanical systems can experience significant friction and wear losses, thereby impairing their efficiency, reliability, and environmental sustainability. Traditionally, these losses have been minimized using high-performance solid and liquid lubricants or surface engineering techniques like physical and chemical vapor deposition. However, increasingly harsh operating conditions of more advanced mechanical systems (including wind turbines, space mechanisms, electric vehicle drivetrains, etc.) render such traditional methods less effective or impractical over the long term. Looking ahead, an emerging and complementary solution could be tribocatalysis, a process that spontaneously triggers the formation of nanocarbon-based tribofilms in situ and on demand at lubricated interfaces, significantly reducing friction and wear even without the use of high-performance additives. These films often comprise a wide range of amorphous or disordered carbons, crystalline graphite, graphene, nano-onions, nanotubes, and other carbon nanostructures known for their outstanding friction and wear properties under the most demanding tribological conditions. This review highlights recent advances in understanding the underlying mechanisms involved in forming these carbon-based tribofilms, along with their potential applications in real-world mechanical systems. These examples underscore the scientific significance and industrial potential of tribocatalysis in further enhancing the efficiency, reliability, and environmental sustainability of future mechanical systems. Full article

With the rapid development of urbanization and tourism in China, increasing attention has been paid to the protection and utilization of historical and cultural heritage, while tourists’ demands for travel experiences have gradually shifted towards in-depth cultural perception. This paper selects Beijing Fayuan Temple Historic and Cultural District as the research case, and adopts methods such as the LDA (Latent Dirichlet Allocation) topic model, collection and analysis of online text data, and field research to explore the current situation of pedestrian space in Fayuan Temple District and its optimization strategies from the perspective of tourists’ perception. The study found that the dimensions of tourists’ perception of the pedestrian space in Fayuan Temple District mainly include six aspects: historical buildings and relics, tour modes and transportation, natural landscapes and environment, historical figures and culture, residents’ life and activities, and tourists’ experiences and visits. By integrating online text data, questionnaire surveys, and on-site behavioral observations, the study constructed a “physical environment-cultural experience-behavioral network” three-dimensional IPA (Importance–Possession Analysis) evaluation model, and analyzed and evaluated the high-frequency perception elements in tourists’ spontaneous evaluations. Based on the current situation evaluation of the pedestrian space in Fayuan Temple District, this paper puts forward optimization strategies for the perception of pedestrian space from the aspects of block space, transportation usage, landscape ecology, digital technology, and cultural symbol translation. It aims to promote the high-quality development of historical blocks by improving and optimizing the pedestrian space, and achieve the dual goals of cultural inheritance and utilization of tourism resources. Full article

Erbium (${\mathrm{Er}}^{3+}$) emitters are relevant for optical applications due to their narrow emission line directly in the telecom C-band due to the ⁴I_13/2 → ⁴I_15/2 transition at 1.54 μm. Additionally, they are promising candidates for future quantum technologies when embedded in thin film silicon-on-insulator (SOI) to achieve fabrication scalability and CMOS compatibility. In this paper we integrate Er³⁺ emitters in SOI metasurfaces made of closely spaced arrays of nanodisks, to study their spontaneous emission via room and cryogenic temperature confocal microscopy, off-resonance and in-resonance photoluminescence excitation at room temperature and time-resolved spectroscopy. This work demonstrates the possibility to adopt CMOS-compatible and fabrication-scalable metasurfaces for controlling and improving the collection efficiency of the spontaneous emission from the Er³⁺ transition in SOI and that they could be adopted in similar technologically advanced materials. Full article

Osteoarthritis involves complex interactions between articular joint tissues and the immune system, which is implicated in molecular trafficking via barrier-function modulating cytokines. The current study aims to test effects of an acute spike in TNF-α or TGF-β on vascular barrier function at multiple length scales, from the heart to tissue compartments of the knee, and cellular inhabitants of those respective compartments, in a spontaneous guinea pig model of osteoarthritis. First we quantified the intensity of a fluorescent-tagged 70 kDa tracer, similar in size to albumin, the most prevalent transporter protein in the blood, in tissue compartments of bone (periosteum, marrow space, compact bone, and epiphyseal bone) and cartilage (superficial cartilage, calcified cartilage, and the interface between, i.e., the epiphyseal line), as well as at sites of tendon attachment to bone (entheses). We then examined tracer presence and intensity in the respective pericellular and extracellular matrix zones of bone and cartilage. Acute exposure to TGF-β reduced barrier function (increased permeability) at nearest vascular interfaces in four of eight tissue compartments studied, compared to TNF-α where one of eight tissue compartments showed significant diminishment in barrier function. The increase in permeability associated with reduced barrier function was observed at both tissue compartment and cellular length scales. The observation of pericellular transport of the albumin-sized molecules to osteocytes contrasts with previous observations of barrier function in healthy, untreated animals and is indicative of increased molecular transport in pericellular regions of musculoskeletal tissues in cytokine-treated animals. Understanding age- and disease-related changes in molecular transport within musculoskeletal structures, such as the knee joint, is crucial for elucidating the etiology and pathogenesis of osteoarthritis. Full article

Background: Supplemental teeth are a rare subtype of supernumerary elements that closely resemble the morphology of normal dentition. Their occurrence in the mandibular anterior region is extremely uncommon. Aim: To describe the clinical features, diagnosis, and phased orthodontic management of a rare case involving bilateral supplemental mandibular incisors in a pediatric patient. Case report: A 7-year-old female patient presented with early mixed dentition and significant lower anterior crowding due to the presence of two fully erupted supplemental mandibular incisors. Treatment phase I included extraction of the malpositioned supplemental teeth and rapid maxillary expansion to transversally coordinate the arches. By the end of phase I, spontaneous alignment of the remaining lower incisors was observed. Discussion: The presence of two supplemental mandibular incisors is extremely rare in Caucasian populations. Supernumerary teeth can cause crowding, impaction, or delayed eruption of adjacent permanent teeth. Timely extraction can prevent such complications and often allows spontaneous alignment. Conclusions: The prompt removal of supplemental mandibular incisors, when they have just erupted, might lead to the alignment of the other incisors, considering that they spontaneously occupy the extractive spaces often without the aid of fixed appliances first line. Full article

In this paper, we present the results of a comprehensive study on how excited-state absorption and concentration effects influence fiber laser efficiency and the optimization of the laser cavity’s output coupler reflection. The concentration effects discussed include the cooperative interaction between two closely spaced active ions and the pair-induced quenching typically observed in heavily doped gain fibers. The laser is simulated using a model based on the laser, pump, and spontaneous emission waves propagating along the gain fiber, where the intensities of these waves determine their absorption or amplification. The model considers the radial distributions of optical fields and populations of the energy levels of the active ions, which is crucial to comply with the law of conservation of energy. The results discussed in this paper are essential for applications related to the optimization of heavily doped fiber lasers. The physics behind the reported results is discussed. Full article

Background: Cervical artery dissection (CAD) is a leading cause of acute ischemic stroke among young and middle-aged patients. Currently, the growing availability of high-resolution magnetic resonance imaging (MRI), particularly fat-saturated T1-weighted black-blood SPACE sequences, allows the non-invasive, rapid, and reliable diagnosis of multiple arterial dissections. Methods: We reported our experience from two tertiary stroke centers of patients diagnosed with spontaneous multiple cervical artery dissections, detected with high-resolution MRI, during a three-year period (2022–2025). Results: Among 95 consecutive patients with CAD, 11 patients (mean age: 48 ± 9 years, 6 (55%) females) were diagnosed with multiple symptomatic or asymptomatic CADs, whereas in 84 patients (mean age: 49 ± 11 years, 32 (38%) females) a single CAD was detected. In all patients, high-resolution MRI and MR-angiography were performed, whereas digital subtraction angiography (DSA) with simultaneous evaluation of renal arteries was conducted in nine patients. A history of trauma or chiropractic manipulations, intense physical exercise prior to symptom onset, recent influenza-like illness, and recent childbirth in a young female patient were reported as predisposing risk factors. Cervicocranial pain, cerebral infarctions leading to focal neurological signs, and Horner’s syndrome were among the most commonly documented symptoms. Characteristic findings in the high-resolution 3D T1 SPACE sequence were detected in all patients. Fibromuscular dysplasia and Eagle syndrome were detected in four patients and one patient, respectively. Eight patients were treated with antiplatelets, whereas three patients received anticoagulation with low-molecular-weight heparin. There was only one case of stroke recurrence during a mean follow-up period of 9 ± 4 months. Conclusions: This case series highlights the utility of specific high-resolution MRI sequences as a very promising method for detecting multiple CADs in young patients. The systematic use of these sequences could enhance the sensitivity of detecting multiple cervical CADs, affecting also the thorough investigation for underlying connective tissue vasculopathies, stratifying the risk for first-ever or recurrent ischemic stroke, and influencing acute reperfusion and secondary prevention therapeutic strategies. Full article

Introduction: Pseudoangiomatous stromal hyperplasia (PASH) is a benign breast lesion characterized by stromal myofibroblast proliferation forming slit-like pseudoangiomatous spaces. Although most frequently diagnosed in premenopausal women, it has also been reported in adolescent girls, where it may present as a rapidly enlarging mass that mimics fibroadenoma or phyllodes tumor. The pathogenesis is thought to be hormonally influenced, particularly by progesterone, with a possible role for estrogen. Case Report: We report the case of a 14-year-old girl who presented with a painless, rapidly growing mass in the left breast, first noticed approximately six months earlier. Clinical examination revealed a mobile lesion about 10 cm in diameter without skin changes, lymphadenopathy, or nipple discharge. Ultrasound and MRI demonstrated a large, well-circumscribed solid tumor (10.4 × 11.2 × 4.2 cm³) displacing normal breast tissue but without infiltration; both were classified as BI-RADS 4. Given the tumor size, diagnostic uncertainty, and potential risk of a non-representative core needle biopsy, a decision was made to proceed with primary radical excision. The mass was completely removed with preservation of the glandular tissue. Histopathology confirmed PASH, described macroscopically as a solid, gray–yellow, encapsulated tumor and microscopically as slit-like spaces lined by spindle cells (CD34+, CD31–). Postoperatively, the breast gradually regained symmetry with the contralateral side, and at 14 months of follow-up, no recurrence was observed. Conclusions: PASH, although benign, may present as a large breast tumor in adolescents and clinically mimic both benign and malignant lesions. Histological evaluation based on an adequately performed biopsy is crucial for accurate diagnosis. Complete excision with capsule preservation is recommended to minimize the risk of recurrence. In adolescents, a watchful waiting approach after surgery may be beneficial, as breast tissue often remodels and regains symmetry spontaneously, reducing the need for reconstructive procedures. This case underscores the importance of individualized diagnostic and therapeutic strategies in managing rare benign breast lesions in pediatric patients. Full article

The knowledge economy has become ever more important for cities and regions, and different types of urban spaces have been created to accommodate its activities. One of the main assets of these spaces is vitality, a quality that is directly related to innovation and is oftentimes considered the result of spontaneous space arrangements. The recent literature, however, shows that urban vitality is not an intangible quality; it can be correlated to different place quality aspects, such as urban morphology, and measured through existing analytical methods. The aim of this paper is to systematize such indicators and use them to develop algorithms that can be subsequently incorporated into a computational tool for the assessment of knowledge territories during the early design stages, to support their spatial planning and development. The Paris-Saclay Urban Campus is used as a case study to understand and assess these vitality and place quality indicators in an existing benchmark. The results can contribute to the serendipity and the success of new or redeveloped knowledge and innovation areas. Full article

Indoor environments significantly influence human interaction, collaboration, and well-being, yet evaluating how architectural designs actually perform in fostering social connections remains challenging. This study demonstrates the use of 11 static-mounted lidar sensors to detect serendipitous encounters—collisions—between people in a shared common space of a mixed academic–residential university building. A novel collision detection algorithm achieved 86.1% precision and detected 14,022 interactions over 115 days (67 million person-seconds) of an academic semester. While occupancy strongly predicted collision frequency overall (R² ≥ 0.74), significant spatiotemporal variations revealed the complex relationship between co-presence and social interaction. Key findings include the following: (1) collision frequency peaked early in the semester then declined by ~25% by mid-semester; (2) temporal lags between occupancy and collision peaks of 2–3 h in the afternoon indicate that social interaction differs from physical presence; (3) collisions per occupancy peaked on the weekend, with Saturday showing 52% higher rates than the weekly average; and (4) collisions clustered at key transition zones (elevator areas, stair bases), with an additional “friction effect”, where proximity to seating increased interaction rates (>30%) compared to open corridors. This methodology establishes a scalable framework for post-occupancy evaluation, enabling evidence-based assessment of design effectiveness in fostering the spontaneous interactions essential for creativity, innovation, and place-making in built environments. Full article

Despite increased interest in embodied learning, the role of sensorimotor activity in shaping students’ probabilistic reasoning remains underexplored. This design-based study examines how high school students develop key probabilistic concepts, including sample space, certainty, and event probability, through whole-body movement activities situated in an authentic classroom setting. Grounded in embodied cognition theory, we introduce a two-axis interpretive framework. One axis spans sensorimotor exploration and formal reasoning, drawing from established continuums in the literature. The second axis, derived inductively from our analysis, contrasts engagement with distraction, foregrounding the affective and attentional dimensions of embodied participation. Students engaged in structured yet open-ended movement sequences that elicited intuitive insights. This approach, epitomized by one student’s spontaneous question, “Can I use my leg too?”, captures the agentive and improvisational character of the embodied learning environment. Through five analyzed classroom episodes, we trace how students shifted between bodily exploration and formalization, often through nonlinear trajectories shaped by play, uncertainty, and emotionally driven reflection. While moments of insight emerged organically, they were also fragile, as they were affected by ambiguity and the difficulty in translating physical actions into mathematical language. Our findings underscore the pedagogical potential of embodied design for probabilistic learning while also highlighting the need for responsive teaching that balances structure with improvisation and supports affective integration throughout the learning process. Full article

Urban tree biodiversity represents a valuable natural resource. However, some fast-growing tree species with limited esthetic value play an important ecological role by colonizing degraded areas, such as closed landfills. Our observations indicate that trees like Betula pendula (Roth), Acer negundo (L.), and Populus tremula (L.) reached the size of adult trees in less than 30 years after the landfill’s closure in the 1990s, forming a nature area similar to a natural forest. A resident survey conducted among the inhabitants of Zgierz confirmed that the lack of space provides opportunities for various forms of recreation. The example analyzed indicates a trend that can be replicated in other cities with minimal human intervention and low financial costs for landfill reclamation. The case study presents an ecological approach to managing degraded sites, where nature determines the quality of the soil environment by eliminating pollutants from the residential surroundings. Furthermore, the research framework provides a basis for developing future models for cleaning up urban landfill sites and promoting placemaking. This pilot study shows a model for old landfills in Europe with well-developed spontaneous vegetation that can be transformed into recreation and sports facilities in the urban areas with industrial past times. Full article

Olive groves (Olea europaea L.) are highly susceptible to soil degradation, particularly water erosion, due to sparse canopy cover and wide inter-row spacing. This study evaluated the effect of different vegetation cover management practices on soil quality and erosion control in a tropical olive grove in southeastern Brazil. The experiment followed a randomized block design with five treatments: exposed soil (BS), olive trees on exposed soil (OB), olive trees with spontaneous vegetation managed with herbicide (OVH), with mowing (OVM), and with mowing + localized weeding (OVMC). Physical, chemical, and biological indicators and losses due to water erosion were analyzed. The OVM and OVMC treatments promoted an increase in soil organic matter (up to 39 g kg⁻¹), microbial biomass carbon (40% higher than BS), enzymatic activity, and glomalin, improving aggregate stability (WMD of 4.9 mm) and reducing soil and water losses by more than 99% compared to exposed soil. The BS and OB treatments, on the other hand, showed higher acidity, lower microbial activity, and greater susceptibility to erosion. The study reinforces that maintaining vegetation cover improves soil quality, mitigates erosion, and promotes the sustainability of olive groves in tropical regions. Full article

In the face of mounting challenges related to limited availability of urban land and ecological degradation, emerging novel ecosystems offer unique opportunities for ecological regeneration, social redefinition of space, and alternative urban visions. This study presents the multi-layer analysis of the Goccia Forest in Milan (Italy), a wild urban woodland that has developed over sealed and polluted post-industrial land, aiming to investigate the potential of this novel ecosystem to sustain Nature-based Solutions (NbSs). Using an integrated approach (surveys on fauna, vascular flora, lichens, analysis of forest evolution, mapping of sealed surfaces, and soil characterization) the research looks at the novel ecosystem as a whole, highlighting its ecological dynamics and Ecosystem Services (ES). La Goccia Forest serves as a prime example of how the implementation of NbSs is intricately intertwined with the spontaneous regeneration of urban brownfields. The present study offers the opportunity to rethink urban policies, ensuring their alignment with the demands of the population and the latest scientific knowledge. Full article

Urbanization profoundly transforms ecosystems, often resulting in habitat loss and biodiversity decline. Urban spontaneous plants, which are established naturally without human intervention, play a critical role in urban ecosystems by providing habitats, mitigating urban heat islands, and acting as indicators of environmental changes. Multidimensional urbanization, encompassing vertical and horizontal scale, exerts a significant influence on the biodiversity of green space. While previous studies have extensively examined the effects of horizontal spatial scales (such as land use and population density), the impacts of vertical spatial scales remain understudied. To elucidate the spatial patterns and driving factors of spontaneous plant diversity under multidimensional urbanization, we conducted a comprehensive survey of spontaneous plants across Changchun, a rapidly urbanizing city in northeast China. We established 1147 herbaceous plots within 245 urban green space patches across 38 sites and analyzed the effects of multidimensional urbanization metrics on spontaneous plant diversity. A total of 408 species of spontaneous plants were recorded, with herbs as the dominant life-form (89.2%), 322 are native species (78.9%), and 21.1% non-native species (of which 65.1% are invasive), primarily dispersed by autochory. Significant differences in plant diversity indices were observed across various urban green spaces and habitat types in Changchun, with native plant diversity generally highest in square green spaces and scrub gaps, while non-native plant diversity was most prominent in brownfield sites and showed no significant variation among habitat types. Regression analyses revealed that, in addition to patch characteristic factors (including patch area, perimeter–area ratio, and landscape shape index), the richness of total, native, and autochorous spontaneous plants was primarily influenced by vertical urbanization (as indicated by building volume), with building volume positively associated with species richness. In contrast, the richness of non-native and anemochorous plants was also significantly affected by horizontal urbanization factors, such as the proportion of impervious surface within a 100 m buffer zone and distance from patch to city center. The results reveal distinct spatial patterns of spontaneous plant diversity driven by both urbanization of horizontal spatial scales and vertical spatial scales. Our study provides new insights into the interplay between multidimensional urbanization and biodiversity, offering a theoretical foundation for integrating biodiversity conservation into sustainable urban planning and ecosystem management. Full article