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Perovskite solar cells (PSCs) represent a promising technology for highly efficient sunlight harvesting and its conversion to electricity at convenient costs. However, a few flaws of current devices undermine the long-term stability of PSCs. Some of them concern the interface between the photoactive perovskite and the hole transport layer (HTL), e.g. undesired charge recombination, polarization barriers and oxidation processes. A strategy to solve this problem is to replace the standard organic HTL (e.g. Spiro-OMeTAD) with a solid-state inorganic layer. Being extensively used in p-type dye sensitized solar cells (DSSCs), nickel oxide (NiO) has been the first choice as an inorganic HTL. Despite the great interests in the application of NiO and other p-type oxides in PSCs, there is no available atomistic model of their interface with a halide perovskite. Here, we address this knowledge gap via a thorough first-principles study of the prototypical PSC perovskite methyl-ammonium lead iodide (MAPI) and two inorganic p-type oxides: NiO and CuGaO2. This copper-gallium delafossite oxide is one of the most promising alternatives to NiO in p-type DSSCs, thanks to its wide optical bandgap and low valence band edge. Here, we characterize the properties of both isolated surface slabs and MAPI/HTL heterostructure models. Besides considering MAPI/NiO and MAPI/CuGaO2 interfaces from the pristine materials, we also address the effects of intrinsic and extrinsic p-type defects in both NiO (Ni vacancy, Ni vacancy with Li and Ag doping) and CuGaO2 (Cu vacancy) using more realistic models. Our study reveals the most convenient interfaces in terms of structural affinities and adhesion energies. From the electronic perspective, we present a detailed analysis on band edge alignments, with direct insights into the key functional parameters of PSCs: hole injection driving force and open circuit potential. Our data show how the presence of defects/dopants is crucial for a convenient hole injection in NiO and CuGaO2. These results provide new science-based design principles for further development of p-type oxides in PSC devices.
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Interconnected network of nanostructured polyaniline (PANI) is giving strong potential for enhancing device performances than bulk PANI counterparts. For nanostructured device processing, the main challenge is to get prototypes on large area by requiring precision, low cost and high rate assembly. Among processes meeting these requests, the alternate current electric fields are often used for nanostructure assembling. For the first time, we show the assembly of nanostructured PANI onto large electrode gaps (30-60 µm width) by applying alternate current electric fields, at low frequencies, to PANI particles dispersed in acetonitrile (ACN). An important advantage is the short assembly time, limited to 5-10 s, although electrode gaps are microsized. That encouraging result is due to a combination of forces, such as dielectrophoresis (DEP), induced-charge electrokinetic (ICEK) flow and alternate current electroosmotic (ACEO) flow, which speed up the assembly process when low frequencies and large electrode gaps are used. The main achievement of the present study is the development of ammonia sensors created by direct assembling of nanostructured PANI onto electrodes. Sensors exhibit high sensitivity to low gas concentrations as well as excellent reversibility at room temperature, even after storage in air.
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Compuestos de Anilina/química , Técnicas Electroquímicas/métodos , Nanoestructuras/química , Nanotecnología/métodos , Amoníaco/análisis , ElectricidadRESUMEN
The feasibility of replacing toxic chlorobenzene antisolvents with environmentally friendly anisole in the fabrication of planar triple-cation perovskite solar cells was explored here. The successful integration of anisole not only ensures comparable device performance but also contributes to the development of more sustainable and green fabrication processes for next-generation photovoltaic technologies. Nevertheless, to ensure the possibility of achieving well-functioning unencapsulated devices whose working operation depends on outdoor atmospheric conditions, we found that adjusting the cesium concentrations in the perovskite layers enabled the electrical characterization of efficient devices even under high relative humidity conditions (more than 40%). We found that 10% of CsI in the precursor solution will make devices with low hysteresis indexes and sustained performance stability over a 90-day period both with cholorobenzene and anisole antisolvent. These results further confirm that green anisole can replace chlorobenzene as an antisolvent.
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BACKGROUND: The capacity to change attention from one area to another depending on the many environmental circumstances present is a crucial aspect of selective attention and is strictly correlated to reaction time. The cholinergic system of the basal forebrain is crucial for attentive abilities. Several inputs, particularly orexin neurons, whose cell bodies are found in the postero-lateral hypothalamus, can activate the cholinergic system. The aim of this study was to investigate if high frequencies rTMS at dorsolateral prefrontal cortex (DLPFC) in highly trained volleyball players can change Orexin-A levels, attention and reaction time. This study was a double-blinded (participant and evaluator) matched-pair experimental design. Twenty right-handed female volleyball players were recruited for the study (age 24.6 ± 2.7 years; height 177.0 ± 5.5 cm; body mass 67.5 ± 6.5 kg; BMI 21.5 ± 1.2). RESULTS: The main finding of this study was that 10 Hz rTMS to the DLPFC seems to increase Orexin-A salivary levels and the percentage of correct answers, while decreasing RT. After rTMS, the athletes show an increase in the percentage of correct answers immediately after the end of stimulation, and also after 15 and 30 min. Moreover, the athletes show decreases in reaction time after the end of stimulation and after 15 and 30 min to the end of stimulation, while no differences were found at the end of stimulation. Finally, the athletes show significant increases in Orexin-A salivary levels after stimulation with a peak after 30' of the end. CONCLUSION: The results of our study seem to indicate that there is a relationship between salivary Orexin-A levels and RT. These results could provide useful tools for modulating sports training; in fact, if confirmed, they could lead coaches to offer their athletes rTMS sessions appropriately integrated with training. In fact, alternating attention is a mental flexibility that enables people to change their point of focus and switch between tasks requiring various levels of cognition.
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Osteoporosis is a common musculoskeletal disorder among the elderly and a chronic condition which, like many other chronic conditions, requires long-term clinical management. It is caused by many factors, including lifestyle and obesity. Bioelectrical impedance analysis (BIA) is a method to estimate body composition based on a weak electric current flow through the body. The measured voltage is used to calculate body bioelectrical impedance, divided into resistance and reactance, which can be used to estimate body parameters such as total body water (TBW), fat-free mass (FFM), fat mass (FM), and muscle mass (MM). This study aims to find the tendency of osteoporosis in obese subjects, presenting a method based on hierarchical clustering, which, using BIA parameters, can group patients who show homogeneous characteristics. Grouping similar patients into clusters can be helpful in the field of medicine to identify disorders, pathologies, or more generally, characteristics of significant importance. Another added value of the clustering process is the possibility to define cluster prototypes, i.e., imaginary patients who represent models of "states", which can be used together with clustering results to identify subjects with similar characteristics in a classification context. The results show that hierarchical clustering is a method that can be used to provide the detection of states and, consequently, supply a more personalized medicine approach. In addition, this method allowed us to elect BIA as a potential prognostic and diagnostic instrument in osteoporosis risk development.
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OBJECTIVES: The ability to redirect one's attention in response to various environmental situations is a crucial aspect of selective attention in team sports. Thus, the aim of this study was to investigate whether repetitive transcranial magnetic stimulation (rTMS) in volleyball players can improve Posner test response and cortical excitability. This study had a double-blinded (participant and evaluator) matched-pair experimental design. METHODS: Twenty right-handed female volleyball players were recruited for the study and randomly assigned to either the active rTMS group (n = 10) or the sham stimulation group (n = 10). The stimulation was performed in one session with 10 Hz, 80% of the resting motor threshold (RMT), 5 s of stimulation, and 15 s of rest, for a total of 1,500 pulses. Before and after stimulation, the Posner test and cortical excitability were evaluated. RESULTS: The significant finding of this paper was that 10 Hz rTMS to the DLPFC seemed to improve Posner test response, and also resulted in a significantly decreased RMT and MEP latency of the ipsilateral motor cortex. After stimulation, the active group showed a significant decrease in the percentage of errors in the Posner test. Moreover, active group showed faster RT after rTMS, suggesting that HF stimulation could enhance performance. Additionally, significant differences in RMT emerged in the active rTMS group after stimulation, while no differences were observed in MEP latency and MEP amplitude. CONCLUSION: In conclusion, we believe that these results may be of great interest to the scientific community and could have practical implications in the future.
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Voleibol , Humanos , Femenino , Estimulación Magnética Transcraneal/métodos , Encéfalo , Potenciales Evocados MotoresRESUMEN
BACKGROUND: The years spent at university represent a critical period that can influence both the quality of lifestyle and the eating habits of subsequent adulthood, and also, in the long term, the health of the individual. The aim of this study was to investigate the lifestyle of university students living away from home. METHODS: Each subject recruited for the study was given a questionnaire to obtain general information, eating habits and physical activity levels before (T0) and after six month of training seminars (T1). Blood pressure, body composition and questionnaire responses were investigated. RESULTS: The main findings of this study are a significant decrement in blood pressure; an increment in physical activity practice; an increased number of subjects who pay attention to the calorific value of food and also an improvement in BIA parameters. CONCLUSIONS: In conclusion, this study demonstrated the challenges that university students face in leading a healthy lifestyle and caring for their nutritional needs, particularly when they are away from their families. No intervention specifically targets young adults, even though much emphasis is placed on the promotion of a healthy lifestyle based on a varied and balanced diet and sufficient exercise. Our study showed that it is possible to improve lifestyle through educational events aimed at making students aware of the health risks deriving from unhealthy lifestyles.