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Produtividade e retorno econômico sob doses de nitrogênio em lavouras de milho irrigado e sequeiro, no município de Buri - SP
(Universidade Federal de São Carlos, 2022-10-20) Oliveira, Gustavo Raphael de; Afférri, Flávio Sérgio; https://lattes.cnpq.br/4868650342029685; https://lattes.cnpq.br/4995640535831099
Nitrogen is essential in corn and the rising prices of this fertilizer become a big problem for producers. Therefore, this research was carried out with the central objective of analyzing the influence of different doses of nitrogen on productivity and economic return in irrigated and rainfed maize under crop conditions, in the municipality of Buri - SP. The treatments in each environment consisted of 4 doses of nitrogen in topdress in the form of urea (40, 80, 120 and 160 kg ha-1) and the experimental design was randomized blocks, with 8 replications. The yield of corn grains in the rainfed and irrigated environments and the economic viability of the nitrogen doses used in the experiments were evaluated. The results showed that there was no significant difference between the averages of nitrogen doses within each environment, however, when analyzing the averages of corn grain yield between the rainfed and irrigated environments, higher productivity was observed in the irrigated environment. Regarding the economic analysis, the highest economic return was verified at the dose of 80 kg ha-1 of N in topdress, being more expressive in the rainfed crop. This research suggests that studies on reducing the dose of N can signal optimization of the use of urea, allowing greater profitability for producers and ensuring a more sustainable agriculture.
Detecção de impressões digitais por meio da luminescência autoativada de nanopartículas de fosfato de cálcio amorfo
(Universidade Federal de São Carlos, 2022-10-20) Silva, Jussara Soares da; Silva, Elson Longo da ; https://lattes.cnpq.br/9848311210578810; https://lattes.cnpq.br/2586454534909121
In this work, stable activator-free photoluminescent nanoparticles based on amorphous calcium phosphate (ACP) were obtained for the first time, and their performance for latent fingerprint imaging was investigated. ACP nanoparticles with irregular rounded shape and diameters in 10–40 nm range were prepared by a rapid and simple chemical precipitation followed by heat treatment at 400 °C for 4 h. Notably, diffuse reflectance spectroscopy, photoluminescence excitation and emission measurements reveal a high density of localized energy states within the wide optical band gap of heat-treated ACP (Eg = 5.25–5.42 eV). This behavior allowed the excitation of ACP in near-ultraviolet region (λexc = 450 nm, 2.75 eV), leading to an intense defect-related broadband (490–890 nm) photoluminescence emission centered at 540 nm (2.30 eV), 50 times more intense than untreated nanoparticles. The effect of lattice shrinkage due to structural water elimination, the presence of ionic vacancies (VCa and VO in PO43-) and carbonate groups (CO32−), on the luminescent properties of ACP were discussed in detail, as well as investigated after aqueous-mediated ACP crystallization into hydroxyapatite (HA). ACP nanoparticles were non-cytotoxic, as determined by MTT assay in Human Dermal Fibroblast neonatal (HDFn) cell line, with cell viabilities superior to 95% in all tested concentrations (20–320 μg/mL), after incubation for 24 and 48 h. Latent fingerprint images were obtained using the ACP nanoparticles under near-ultraviolet irradiation (λexc = 450 nm) in tweezers and LCD smartphone and successfully validated by the Integrated Automated Fingerprint Identification System used by Scientific Police in Spain. The present results evidenced that the new luminescent ACP nanoparticles are safe to be used and agree with the forensic requirements for future legal actions.