University of Amsterdam

Salivary dysfunction, including xerostomia and drooling, is common in Parkinson's disease and further impairs oral health and quality of life, which are already compromised in this population. Their effective management demands deeper insight into the complexity of salivary dysfunction. To examine the occurrence and associations of xerostomia and drooling complaints in individuals with Parkinson's disease. 111 individuals with Parkinson's disease (69.9 ± 7.7 years; 46.8% female) participated in an online survey. The questionnaire used validated scales (e.g., Xerostomia Inventory) and original questions. After descriptive analyses, multiple linear regression analyses identified factors (e.g., severity of motor impairment) associated with severity of xerostomia and drooling. Xerostomia (64.9%) and drooling (27.0%) were common, with 18.0% of the individuals experiencing both concurrently. Xerostomia was associated with the presence of jaw symptoms (B = 4.63; 95% CI 1.86-7.40), chewing gum usage (B = 1.27; 95% CI 0.52-2.02), swallowing difficulties (B = 0.41; 95% CI 0.04-0.78) and taste alterations (B = 0.15; 95% CI 0.00-0.30). Drooling was associated with the severity of motor impairment (B = 0.40; 95% CI 0.18-0.60) and with swallowing difficulties (B = 0.64; 95% CI 0.14-1.15). Xerostomia and drooling complaints frequently co-occur in individuals with Parkinson's disease. To prevent further deterioration of the oral health-related quality of life, a comprehensive evaluation of the underlying aetiology of salivary issues in people with Parkinson's disease is crucial to assist in determining suitable treatment.

Peer interactions in early childhood education and care (ECEC) contribute to young children’s development. Earlier studies show that children’s linguistic resources might relate to how much they interact with peers, and with whom they interact. However, it is unclear to what extent interaction preferences are shaped by young children’s language background, language proficiency, and communicative competence. In this exploratory study, we tried to examine this question using the latest innovations in social network analysis, namely generalized exponential graph models and observation apps. We investigated to what extent children’s linguistic resources are related to whom they interact with and how much. We observed a free play episode (30-60 minutes) in twelve linguistically diverse toddler groups in the Netherlands (N=124) with a specifically designed observation app and looked at which children interacted and how much. Exploratory analyses across nine playgroups showed that children who shared a home language had more interactions with each other. There was no effect of multilingualism or ECEC language proficiency on peer interactions. We found that teacher involvement in free play was positively related to the quantity of peer interactions. In terms of practical implications, this suggests that teachers play an important role in stimulating (multilingual) children’s peer interactions in ECEC. Teachers might be advised to connect multilingual children to same-language peers and encourage translanguaging practices. • We studied toddlers’ peer interactions in relation to their linguistic resources • A dedicated observation app and generalized exponential graph models were used • Children who shared a home language had more interactions with each other • There was no effect of multilingualism or language proficiency on peer interactions • Teacher involvement during free play was positively related to peer interactions

• Predominant ASGM research focus on environmental state and impacts. • Ecological and social systems are studied in isolation. • Little emphasis on the spatial extent of ASGM mediated pollution. • Need for future ASGM research to determine mechanistic interactions between DPSIR elements and how they shape social-ecological systems. Artisanal and small-scale gold mining (ASGM) has long been a lucrative source of income globally. Today, ASGM is concentrated in low- and middle-income countries, and its extraction and processing have detrimental consequences for the environment as well as human health and livelihoods. We systematically reviewed 145 articles published between 1978 and 2024 on the effects of ASGM on social and ecological systems worldwide. Using the Driver-Pressure-State-Impact-Response (DPSIR) framework, we critically examine where past research has focused and where it has fallen short in understanding the mechanisms that drive impacts and responses to ASGM. Research has predominantly focused on changes in the state of environmental systems and subsequent ecological and socio-economic impacts. In contrast, the driving factors of ASGM and response strategies have been much less studied, while understanding of interactions across all DPSIR elements remains lacking. Furthermore, research has taken a local lens, giving little attention to the spatial extent of ASGM activities and their impacts. Our analysis thus reveals important gaps in understanding the complex mechanisms driving ASGM adoption and the extent to which responses can mitigate negative impacts. To inform effective policy interventions, future research should emphasize mechanistic and spatial interactions of DPSIR elements and how they shape social-ecological systems.

To assess how resin cement viscosity and thickness influence the static shear bond strength (s-SBS) of adhesively bonded lithium disilicate ceramic. Cylindrical lithium disilicate samples were prepared and randomly assigned to four experimental groups (n = 10), based on two factors: resin cement thickness (thin ≈50 µm or thick ≈150 µm) and viscosity (high or low). A tri-layer configuration (ceramic-resin cement-ceramic) was used, with standardized ceramic discs obtained from CAD/CAM blocks. The bonding ceramic surfaces were etched with hydrofluoric acid, silanized, and a defined bonding area (≈6 mm2) was delimited using adhesive tape. The resin cement thickness was controlled by applying either one (thin) or three (thick) overlapping layers of adhesive tape. Resin cement was applied, and assemblies were seated under a 100 g static load. After light-curing, specimens were subjected to static shear bond strength testing (s-SBS) using a universal testing machine (crosshead speed: 1 mm/min; load cell: 1 kN). Failure mode was classified under stereomicroscopy, and representative samples were analysed under SEM. Additional specimens were used to confirm cement layer thickness using a profilometer. For the thick resin cement layer (≈150 µm), viscosity significantly influenced bond strength, with high-viscosity cement showing higher mean values (27.36 MPa) compared to the low-viscosity cement (19.65 MPa). In contrast, resin cement viscosity did not affect the bond strength in the thin layer condition (≈50 µm). Most specimens exhibited adhesive failure at the ceramic-cement interface. Resin cement selection based on viscosity is particularly relevant when a thick cement layer is anticipated, whereas for ideal, thin cement films, viscosity is a less consequential factor for interfacial bond strength.

Ultra-weak Photon Emission (UPE) is thought to represent chemiluminescence from oxidative metabolic processes. This study aimed to characterize UPE dynamics during transient ischemia and reperfusion, while systematically assessing the reproducibility of both baseline and intervention-induced UPE measurements. UPE was recorded from the hands of 30 participants across two separate sessions using a custom-built photon-counting system. Transient ischemia was induced by a two-minute upper-arm tourniquet application. The stability and reproducibility of these measurements were evaluated using Bland-Altman analysis, Pearson correlations, and within-subject Coefficient of Variation (wsCV). UPE intensity exhibited a distinct multiphasic response to blood flow restriction: A sharp decline during ischemia (reaching ∼85% of baseline) followed by stabilization during reperfusion at approximately 95% of baseline. Baseline measurements exhibited high intrasession reproducibility (r=0.97, wsCV=11.3%) but only moderate intersession reproducibility (r=0.59, wsCV=34.4%). During the intervention, reproducibility was moderate in the ischemic phase (r=0.66, wsCV=43.6%), whereas the reperfusion phase showed substantially greater variability (r=0.32, wsCV=99.9%). In contrast, normalized AUC quantification produced stronger intersession linear associations and improved reproducibility across both the baseline-ischemia (r=0.83, wsCV=28.3%) and reperfusion segments (r=0.80, wsCV=35.1%). UPE is able to capture a dynamic physiological response to blood flow restriction that follows a consistent temporal trend despite significant individual variability. This study establishes quantitative benchmarks for UPE measurement stability, positioning it for future consideration as a non-invasive tool for monitoring oxidative metabolic activity in vivo.

In patients with contact allergy to Chinese propolis, co-reactivity to the four fragrance markers present in the European baseline series ( Myroxylon pereirae resin [balsam of Peru], colophonium, fragrance mixes 1 and 2) has been well documented. The co-reactivity pattern of Brazilian propolis has not yet been sufficiently analysed. To investigate co-reactivity patterns to the fragrance markers and to the fragrances linalool hydroperoxides and limonene hydroperoxides in patients reacting to Chinese and Brazilian propolis. Retrospective analysis of patch test results in a cohort of 701 patients tested with Chinese propolis and a cohort of 2509 individuals tested with Brazilian propolis investigated in Amsterdam during 2019-2025. For Chinese propolis, we found significant associations with the four fragrance markers and limonene hydroperoxides. For Brazilian propolis, there were significant associations with all four fragrance markers and both limonene and linalool hydroperoxides. There were indications of a closer relationship between Brazilian propolis and fragrances than of Chinese propolis and fragrances, possibly resulting in many more positive patch test reactions to the Brazilian variety. Significant co-reactivity to fragrances and -marker(s) was confirmed for patients allergic to Chinese propolis and established for patients with positive patch tests to Brazilian propolis.

Fruits and nuts develop resilient outer shells to safeguard their embryos against environmental hazards and predators. The nuts of the marri tree (Corymbia calophylla) possess unusual strength and toughness. In contrast to other tough nuts, seasoned parrots avoid cracking them and instead resort to drawn-out attempts to snatch their seeds from a dispersal opening at their base. Here, we reveal the subtle strengthening mechanisms of the marri nut and compare its mechanical response and properties to those of other nuts and commercial materials. The analysis involves an extensive examination of the various material phases of the nutshell, the chemical composition of its fibers, and an analysis of its microscopic and macroscopic mechanical properties. The study reveals that, akin to self-standing structures, the interplay of the densely packed fibers of the shell held together by a highly ductile soft matrix, while arranged in a spherical configuration, gives the nut its notable toughness, ductility, strength, and remarkable fracture resistance. Additionally, we design and test the mechanical behavior of a bioinspired interpenetrating phase composite material mimicking the nut's microstructure, demonstrating comparable deformability and toughness. These findings lay a new foundation for designing highly efficient bioinspired structures for energy absorption, protection, and armor.