Polyethylene terephthalate (PET) micro- and nanoplastic particles affect the mitochondrial efficiency of human brain vascular pericytes without inducing oxidative stress

The objective of this investigation was to evaluate the influence of micro- and nanoplastic particles composed of polyethylene terephthalate (PET), a significant contributor to plastic pollution, on human brain vascular pericytes. Specifically, we delved into their impact on mitochondrial functionality, oxidative stress, and the expression of genes associated with oxidative stress and ferroptosis. Our findings demonstrate that the exposure of a monoculture of human brain vascular pericytes to PET particles in vitro at a concentration of 50 ppm for a duration of 6 days did not elicit oxidative stress. Notably, we observed an augmentation in various aspects of mitochondrial respiration, including extracellular acidification, proton pump leakage, maximal respiration, spare respiratory capacity, and ATP production in pericytes subjected to PET particles. Furthermore, there were no statistically significant alterations in mitochondrial DNA copy number, or the expression of genes linked to oxidative stress and ferroptosis. These outcomes suggest that, at a concentration of 50 parts per million (ppm) and for 6 days exposure, PET particles do not induce oxidative stress in human brain vascular pericytes. Instead, they seem to incite a potential mitochondrial hormesis, also named mitohormesis, response, which seemingly enhances mitochondrial function. Further investigations are warranted to explore the stages of mitohormesis and the potential consequences of plastics on the integrity of the blood-brain barrier and intercellular interactions. This research contributes to our comprehension of the potential repercussions of nanoplastic pollution on human health and underscores the imperative need for ongoing examinations into the exposure to plastic particles

Connecting the dots between root, xylem and stomata

2 páginas.- 3 referencias.- Comunicación oral presentada en el BP2021: XXIV Reunión de la Sociedad Española de Biología de Plantas y XVII Congreso Hispano-Luso de Biología de Plantas, 7 y 8 de julio de 2021. onlineStomata are present on all land plants and are key features for vascular plant water content regulation on Earth. Their primary function, i.e., stomatal closure to control water los s under soil and atmospheric drought, is Ihought to prevent cavitation in the vascular system (Brodribb et al. 2017). However, stomata are found to close much before the xylem cavitates - i.e., the leaf water potential at which stomata close by 50% (IV gs50) is much less negative than the water potential at which the xylem loses 50% of its conductivity (lV_x50) (Martin-St Paul et al. 2017). The mechanism that would allow sto mata to close promptly to a decrease in transpiration in relation to a change in leaf water potential before the decrease in hydraulic conductance is still elusive. Our hypothesis is that the loss of root-soil hydraulic conductivity, more than xylem vulnerability to embolisms, is Ihe primary constraint on transpiration during drought (RodriguezDominguez and Brodribb 2020). Thus, sto mala would close when the water potential around the roots drops more rapidly than the increase in transpiration. We investigated whether this loss of root-soil hydraulic conductivity, probably caused due to root shrinkage and the formation of air-filled gaps, aml/or damage to fine roots, appeared to be an important constraint on transpiration during drought. We conducted physiological and imaging experiments on maize plants undergoing moderate drought. We performed highresolution imaging (micro-CT) of leaves and the root-soil interface and measured in parallel the soil and plant water potentials. Transpiration, stomatal conductance, root hydraulic conductance and soil and plant water potential were also measured during soil drying in a similar set of plants. The formation of air-filled gaps along individual maize roots was visualized and quantified, finding an agreement between the soil water potential at which roots shrank and root hydraulic conductance decreased, and the soil water potential at which sto mata c1osed. These results proved the hypothesis that the loss of contact between roots and soil, and probably other root cortex modifications, triggered stomatal c10sure and transpiration reduction.Microcomputed tomography measurements were conducted at the PSYCHE beamline at SOLEIL Synchrotron (Paris, France). C.M.R-D. was supported by a "Juan de la Cierva - Incorporación" post-doctoral fellowship (Spain) and was granted a Junior Fellowship by the University of Bayreuth Centre of Intemational Excellence "Alexander von Humboldt" for conducting this specific experiment.N

The impact of the urban canyon geometry in the nocturnal heat island intensity: analysis by a simplified model adapted to a GIS

A geometria urbana é um dos fatores de maior influência na intensidade da ilha de calor urbana. Seu estudo requer a caracterização de cânions urbanos, geralmente medidos pela relação entre a altura dos edifícios e a largura da rua (H/W), conceito aplicado no modelo numérico de Oke em 1981. O objetivo deste artigo é verificar o impacto da geometria do cânion urbano na intensidade de ilhas de calor noturna. Para isso, foram realizados levantamento de dados climáticos e de geometria urbana em duas cidades brasileiras. Os valores de intensidade de ilha de calor foram confrontados com os simulados pelo modelo original de Oke (1981), o qual foi calibrado e adaptado à plataforma SIG, de forma a possibilitar a incorporação de outro parâmetro de geometria, além da relação H/W: o comprimento de rugosidade. Esse processo gerou uma nova ferramenta de cálculo, que é denominda THIS (Tool for Heat Island Simulation). Aplicou-se o novo modelo para simular alguns cenários urbanos hipotéticos, que representam vários tipos de cânions urbanos. Os resultados demonstraram que cânions urbanos de maior rugosidade amenizam as intensidades de ilha de calor noturna em relação a um cânion de mesmo valor de relação H/W e menor rugosidade.Urban geometry is one of the main factors influencing the development of urban heat islands. The study of urban geometry requires a characterization of urban canyons, which can be usually measured by the H/W ratio (a relationship between the height and the width of a street), a concept applied in a numerical model by Oke in 1981. The aim of this paper is to verify the impact of the canyon geometry on the intensity of the nocturnal urban heat islands. For this purpose, measurements of climate data and urban geometry were conducted in two Brazilian cities. The values of heat island intensity were cross-examined to those generated with the application of the original Oke's model. Therefore, this latter was calibrated and adapted to run in a GIS platform, allowing the incorporation of a geometric parameter other than the H/W ratio - the roughness length. Then, this process produced a new calculation tool, which is called THIS (Tool for Heat Island Simulation). The new model was applied to simulate some hypothetical urban scenarios representing several urban canyons types. The results showed that the urban canyons with the largest roughness reduce the nocturnal heat island intensities in relation to an urban canyon of the same H/W value, but presenting lower roughness rates instead.Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Differential scanning calorimetry analyses of Al-Cu-Zn alloys

The effect of heat treatment on phase transformation and crystalline microstructure properties of ternary Al-Cu-Zn alloys made under nonequilibrium conditions was investigated by means of differential scanning calorimetry spectrometry (DSC), optical microscopy observations and X-ray diffraction (XRD) patterns analyses. A set of ternary Al-X wt.% Cu-X wt.%Zn alloys with nominal compositions X = 2, 8, 20 and 25 were rapidly solidified under vacuum by high-frequency magnetic induction melting process. It was found that DSC heating at temperatures below 500 °C leads to phase transformation with the development of new phases which were identified by XRD patterns analyses such as the presence at ambient temperature of the rhomboedric structure τ′-Al4Cu3Zn phase in equilibrium with the expected tetragonal θ-CuAl2 in Al matrix. Measured DSC crystallization enthalpies of occurring phase transformation were given. Optical microscopy observations reveal refined grains and homogeneous surface textures of the as-melted Al-Cu-Zn alloys

CLIMATE IMPACT ON THE ABUNDANCE OF SOIL MACROINVERTEBRATES IN ALGERIAN OLIVE ORCHARDS

Abstract The current study gather

Microstructure properties of rapidly solidified Al-Cu-Zn alloys

In this article, the microstructural properties of the phases which form in samples of some aluminium-based alloys, have been investigated. The study was focussed on the characteristic parameters of the formed phases in the ternary Al(rich)-Cu-Zn alloys by means of X-ray diffraction (XRD) analysis and optical microscopy observations. The bulk materials of ternary Al-X wt.%Cu-X wt.%Zn (X = 2, 8, 20, 25) alloys have been made under vacuum by the high frequency (HF) magnetic induction melting process and rapidly solidified at ambient temperature from compacted composite targets of a mixture of high purity (99.99%) of Al , Cu and Zn laboratory powders. Results are correlated with that of binary Al-Cu alloys