Testing the Dispersion of Nanoparticles in a Nanocomposite with an Ultra-Low Fill Content Using a Novel Non-Destructive Evaluation Technique

A non-destructive evaluation (NDE) technique capable of testing the dispersion of nanoparticles in a nanocomposite would be of great use to the industry to check the quality of the products made and to ensure compliance with their specifications. Very few NDE techniques found in the literature can evaluate the level of dispersion of the nanoparticles in the whole nanocomposite. Here, a recently developed NDE technique based on pulsed phase thermography (PPT) in transmission mode was used to assess the particle dispersion in ultra-low, less than 0.05 wt%, Ag enriched polymeric based nanocomposite manufactured with an innovative nano-coating fragmentation technique. The phasegrams obtained with the presented technique clearly showed clusters or bundles of Ag nanoparticles when present, down to the size of 6 µm. Therefore, the new NDE approach can be applied to verify that the expected levels of dispersion are met in the production process

CO2 laser ablation of oral leukoplakia: with or without extension of margins?

The purpose is to determine the sufficient extension of margins during laser ablation of oral leukoplakia and observe its short-term recurrence rate. Materials and Methods.The study was designed as a randomized controlled clinical trial was conducted on 33 oral leukoplakia lesions diagnosed in 30 patients (16 Females and 14 Males) with an age range between 39 and 79 years. The lesions were divided into three groups; Group A: 11 lesions in 11 patients, in which the laser ablation was done for the entire lesion without extension of margins; Group B: 11 lesions in 8 patients, in which the laser ablation was done for the lesion adding at least 3mm extension of margins; and finally the Group Control: consists of 11 untreated lesions in 11 patients, in which only “wait and see” approach was done. Results. Complete healing of 13 lesions occurred in both groups A and B. Complete regression of 3 lesions occurred in Group Control. After 6 months of follow-up, 6 of 9 lesions in both groups A and B that showed the recurrence, had shown an initial recurrence after 3 weeks of the laser ablation. Patients with no history of smoking habits showed complete healing of 87.5%, while in ex-smokers complete healing was 42.8%. The statistical analysis was performed, and the averages of all groups are significantly different (p <0.00001).Discussion.The primary treatment focuses on the elimination of associated risk factors (smoking, alcohol, and local irritating factors). In the literature, the recurrence rate varies between 13.6% and 40.7%, while in our study, it was 45.5% in Group A and 36.4% in Group B. Conclusion.The recommended extension of margins should be at least 3mm in width. Further research can be performed to evaluate the immediate re-ablation of the lesions which showed an initial recurrence after 3 weeks of laser ablation

Acoustic Signatures of Habitat Types in the Miombo Woodlands of Western Tanzania

The Miombo Woodlands of Tanzania comprise several habitat types that are home to a great number of flora and fauna. Understanding their responses to increasing human disturbance is important for conservation, especially in places where people depend so directly on their local ecosystem services to survive. Soundscapes are a powerful approach to study complex biomes undergoing change. The sounds emitted by soniferous fauna characterize the acoustic profile of the landscapes they inhabit such that habitats with the highest acoustic abundance are considered as the most diverse and possibly more ecologically resilient. However, acoustic variability within similar habitat types may pose a challenge not only in determining their pristine condition but also in acoustically detecting their ecological change. The study presented here attempts to assess the soundscapes across habitat types in the Miombo Woodlands of the Issa Valley, Tanzania. A set of 24-hour audio recordings was collected using passive acoustic recorders over an area of 18000 km2. Sites were clustered based on acoustic indices that quantified sound diversity, and this cluster was compared to a similar cluster based on habitat physical attributes calculated using MODIS imagery and geographic information systems. The culminating analysis is a statistical correlation between habitats as defined by their soundscapes and by their landscape attributes. Results indicate acoustic variability was greater in dense canopy habitats and that wetland soundscapes are strongly correlated to the landscape attributes. More analysis need to be done to detect further ecological factors affecting the soundscape in places where the variability was high

The formation of SCEs as an effect of occupational exposure to formaldehyde

Formaldehyde (FA) is a ubiquitous toxic chemical employed worldwide due to its disinfectant and preservative properties. Despite being classified as a human carcinogen, FA is still employed as formalin in pathology wards as standard fixative. We evaluated its relationship with the formation of sister-chromatid exchanges (SCEs) in cultured peripheral blood lymphocytes on 57 pathologists and 48 controls and the risk/protective role played by several genetic polymorphisms. All subjects were assessed for SCEs and genotyped for the most common cancer-associated gene polymorphisms: CYP1A1 exon 7 (A > G), CYP1A1*2A (T > C), CYP2C19*2 (G > A), GSTT1 (presence/absence), GSTM1 (presence/absence), GSTP1 (A > G), XRCC1 (G399A), XRCC1 (C194T), XRCC1 (A280G), XPC exon 15 (A939C), XPC exon 9 (C499T), TNFα − 308 G > A), IL10 − 1082 (G > A), and IL6 − 174 (G > C). Air-FA concentration was assessed through passive personal samplers. Pathologists, exposed to 55.2 μg/m(3) of air-FA, showed a significantly higher SCEs frequency than controls, exposed, respectively, to 18.4 μg/m(3). Air-FA was directly correlated with SCEs frequency and inversely with the replication index (RI). Regression models showed FA exposure as a significant predictor in developing SCEs, while did not highlight any role of the selected polymorphisms. Our study confirms the role of low air-FA levels as genotoxicity inductor, highlighting the importance to define exposure limits that could be safer for exposed workers. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00204-022-03238-w

Trehalose administration in C57BL/6N old mice affects healthspan improving motor learning and brain anti-oxidant defences in a sex-dependent fashion: a pilot study

Aim of this study was to characterize the effects of oral trehalose administration (2%w/v) on healthspan in old mice. Trehalose was administered in drinking water for 1 month to male and female C57BL/6N mice aged 25-months. After behavioral phenotyping (grip strength, beam walking and rotarod tests), autophagy (LC3-II/actin) and oxidative stress were tested in the cerebral cortex and gastrocnemius muscle. The latter parameter was indirectly assessed by evaluating carbonyl groups added to proteins as a result of oxidative reactions, in addition to central levels of NRF2 protein, a transcription factor that regulates the expression of antioxidant enzymes. In comparison with sex-matched controls, trehalose-treated males performed better in motor planning and coordination tasks. This behavioral phenotype was associated with an activation of the ubiquitin-proteasome system, autophagy and antioxidant defences in cerebral cortex. Independently from trehalose administration, females were characterized by better motor performance and showed higher levels of ubiquitinated proteins and NRF2 in cerebral cortex, suggesting an up-regulation of basal antioxidant defences. In conclusion, trehalose was effective in counteracting some aspects of age-related decay, with specific effects in male and female subjects

Assessing the inhaled dose of nanomaterials by nanoparticle tracking analysis (NTA) of exhaled breath condensate (EBC) and its relationship with lung inflammatory biomarkers.

The widespread and increasing use of nanomaterials has resulted in a higher likelihood of exposure by inhalation for nanotechnology workers. However, tracking the internal dose of nanoparticles deposited at the airways level, is still challenging. To assess the suitability of particle number concentration determination as biomarker of internal dose, we carried out a cross sectional investigation involving 80 workers handling nanomaterials. External exposure was characterized by portable counters of particles DISCminiTM (Testo, DE), allowing to categorize 51 workers as exposed and 29 as non-exposed (NE) to nanoparticles. Each subject filled in a questionnaire reporting working practices and health status. Exhaled breath condensate was collected and analysed for the number of particles/ml as well as for inflammatory biomarkers. A clear-cut relationship between the number of airborne particles in the nano-size range determined by the particle counters and the particle concentration in exhaled breath condensate (EBC) was apparent. Moreover, inflammatory cytokines (IL-1β, IL-10, and TNF-α) measured in EBC, were significantly higher in the exposed subjects as compared to not exposed. Finally, significant correlations were found between external exposure, the number concentration of particles measured by the nanoparticle tracking analysis (NTA) and inflammatory cytokines. As a whole, the present study, suggests that NTA can be regarded as a reliable tool to assess the inhaled dose of particles and that this dose can effectively elicit inflammatory effects

Seasonal patterns and controls on net ecosystem CO2 exchange in a boreal peatland complex

We measured seasonal patterns of net ecosystem exchange (NEE) of CO2 in a diverse peatland complex underlain by discontinuous permafrost in northern Manitoba, Canada, as part of the Boreal Ecosystems Atmosphere Study (BOREAS). Study sites spanned the full range of peatland trophic and moisture gradients found in boreal environments from bog (pH 3.9) to rich fen (pH 7.2). During midseason (July‐August, 1996), highest rates of NEE and respiration followed the trophic sequence of bog (5.4 to −3.9 μmol CO2 m−2 s−1) \u3c poor fen (6.3 to −6.5 μmol CO2 m−2 s−1) \u3c intermediate fen (10.5 to −7.8 μmol CO2 m−2 s−1) \u3c rich fen (14.9 to −8.7 μmol CO2m−2 s−1). The sequence changed during spring (May‐June) and fall (September‐October) when ericaceous shrub (e.g., Chamaedaphne calyculata) bogs and sedge (Carex spp.) communities in poor to intermediate fens had higher maximum CO2 fixation rates than deciduous shrub‐dominated (Salix spp. and Betula spp.) rich fens. Timing of snowmelt and differential rates of peat surface thaw in microtopographic hummocks and hollows controlled the onset of carbon uptake in spring. Maximum photosynthesis and respiration were closely correlated throughout the growing season with a ratio of approximately 1/3 ecosystem respiration to maximum carbon uptake at all sites across the trophic gradient. Soil temperatures above the water table and timing of surface thaw and freeze‐up in the spring and fall were more important to net CO2 exchange than deep soil warming. This close coupling of maximum CO2 uptake and respiration to easily measurable variables, such as trophic status, peat temperature, and water table, will improve models of wetland carbon exchange. Although trophic status, aboveground net primary productivity, and surface temperatures were more important than water level in predicting respiration on a daily basis, the mean position of the water table was a good predictor (r2 = 0.63) of mean respiration rates across the range of plant community and moisture gradients. Q10 values ranged from 3.0 to 4.1 from bog to rich fen, but when normalized by above ground vascular plant biomass, the Q10 for all sites was 3.3