Struvite-based composites for slow-release fertilization: a case study in sand

Struvite (St) recovered from wastewaters is a sustainable option for phosphorus (P) recovery and fertilization, whose solubility is low in water and high in environments characterized by a low pH, such as acidic soils. To broaden the use of struvite in the field, its application as granules is recommended, and thus the way of application should be optimized to control the solubility. In this study struvite slow-release fertilizers were designed by dispersing St particles (25, 50, and 75 wt%) in a biodegradable and hydrophilic matrix of thermoplastic starch (TPS). It was shown that, in citric acid solution (pH = 2), TPS promoted a steadier P-release from St compared to the pure St pattern. In a pH neutral sand, P-diffusion from St-TPS fertilizers was slower than from the positive control of triple superphosphate (TSP). Nevertheless, St-TPS featured comparable maize growth (i.e. plant height, leaf area, and biomass) and similar available P as TSP in sand after 42 days of cultivation. These results indicated that St-TPS slow P release could provide enough P for maize in sand, achieving a desirable agronomic efficiency while also reducing P runoff losses in highly permeable soils.info:eu-repo/semantics/publishedVersio

Avaliação do potencial de uso da hidroxiapatita para fertilização de solos

Plants absorb phosphorus from the soil, which has low levels of this element due to the poor solubility of these compounds in soil and high adsorption capacity of the element by soil particles. Therefore, the purpose of this study was to assess, using hydroxyapatite nanoparticles synthesized in the laboratory, the amount of phosphorus available under different conditions. The results showed that the phosphorus compound had highest solubility in hydroxyapatite sintered at 300°C in an oven for 2h and diluted to 0.05M with MilliQ water, corroborating the theory that the stronger the agglomeration of the nanoparticles, the fewer the pores and the poorer their solubility

Growth kinetics of vanadium pentoxide nanostructures under hydrothermal conditions

The work reported here involved a study of the growth kinetics of V2O5nH2O nanostructures under hydrothermal conditions. The coarsening process of V2O5nH2O nanoribbons was followed by subjecting the as-prepared suspensions to hydrothermal treatments at 80 °C for periods ranging from 0 to 7200 min. X-ray diffraction (XRD) confirms that the hydrothermal treatments at 80 °C caused no significant modification of the long-range order structure of samples subjected to different periods of hydrothermal treatment. Field emission scanning transmission electron microscope (FE-STEM) was used to analyze the morphology and width distribution of the nanostructures. The results indicated that the crystal growth mechanism in the [1 0 0] direction of vanadium pentoxide 1D nanostructure under hydrothermal conditions is well described by the oriented attachment (OA) mechanism. This evidence was supported by HRTEM images showing the existence of defects at the interface between nanostructures, which is characteristic of the oriented attachment (OA) mechanism.FAPESPCNPqLNL

Comercialização de alimentos no Brasil

Este trabalho reflete sobre a instrumentalização das grandes redes de supermercados para o escoamento da produção das grandes empresas do setor agroalimentar. Sua atuação contrasta com o atual momento que a sociedade brasileira atravessa no combate a fome, esta antiga assombração que acompanha 33,1 milhões de brasileiros. O objetivo deste trabalho consiste em relacionar o atual quadro de insegurança alimentar e nutricional com a atuação destes equipamentos de varejo alimentar. Seu desempenho está alinhado com os interesses financeiros que colaboram para as lavouras de monoculturas quanto para a padronização do consumo de alimentos no Brasil de modo que o custo da cesta básica aumenta junto com a depressão da renda dos trabalhadores. Dessa forma, a alternativa para se alimentar é o endividamento que resulta no fortalecimento desses grupos financeiros enquanto a maior parte dos agentes envolvidos está diante forte vulnerabilidade tanto no meio rural quanto no urbano

The interplay between morphology and photocatalytic activity in ZnO and N-doped ZnO crystals

Photocatalytic materials can perform oxidative and reductive reactions over their surfaces when excited with light. Intrinsic characteristics of the material such as superficial area, morphological structure, and crystalline phase exposition play a fundamental role in the corresponding reaction paths. However, especially in doped semiconductors, as ZnO:N, less is known about how the synthesis parameters affect the morphologies and the photocatalytic activity simultaneously. To solve this issue, ZnO and ZnO:N samples were obtained using microwave-assisted hydrothermal and modified polymeric precursor methods of synthesis. Samples morphologies were characterized by TEM and FE-SEM. Crystallographic phases were observed by XRD and optical characteristics by DRS. XPS results confirmed the doping process. Degradation of Rhodamine-B and Cr(VI) reduction were employed as probe reactions to investigate their photocatalytic activity. Although the crystallographic structure of these powders maintains the ZnO hexagonal wurtzite structure, the optical properties and morphologies, and photocatalytic activities present different behaviors. Also, density functional theory calculations were employed to determine the specific features related to electronic structure, morphology, and photocatalytic activity. Different synthesis methods produce a singular behavior in the physicochemical properties of materials, and the doping effect produces various modifications in RhB degradation and Cr(VI) reduction for each synthesis method. Crystal face exposition and morphologies are related to the improvement in the photocatalytic activity of the materials.The authors acknowledge São Paulo Research Foundation (FAPESP), grants #2014/17343-0, #2015/04511-5, #2013/26671-9, #CEPID 2013/ 07296-2. National Council for Scientific and Technological Development – CNPQ, grant #444926/2014-3. J. A. acknowledges the financial support of the Spanish research funding projects: PrometeoII/2014/022 and ACOMP/2014/270 and ACOMP72015/1202 projects (Generalitat Valenciana), CTQ2015-652017-P and Salvador Madariaga program, PRX15/00261 (Ministerio de Economía y Competitividad) and Spanish-Brazilian Program (PHBP14-00020). The XPS facilities were provided by LNNano/CNPEM (Brazilian Nanotechnology Nation Laboratory, Proposal no. 20389)

Ion-sensing properties of 1D vanadium pentoxide nanostructures

The application of one-dimensional (1D) V2O5 center dot nH(2)O nanostructures as pH sensing material was evaluated. 1D V2O5 center dot nH(2)O nanostructures were obtained by a hydrothermal method with systematic control of morphology forming different nanostructures: nanoribbons, nanowires and nanorods. Deposited onto Au-covered substrates, 1D V2O5 center dot nH(2)O nanostructures were employed as gate material in pH sensors based on separative extended gate FET as an alternative to provide FET isolation from the chemical environment. 1D V2O5 center dot nH(2)O nanostructures showed pH sensitivity around the expected theoretical value. Due to high pH sensing properties, flexibility and low cost, further applications of 1D V2O5 center dot nH(2)O nanostructures comprise enzyme FET-based biosensors using immobilized enzymes.CAPESCAPESCNPqCNPqFAPESPFAPES

Adverse events following immunization of elderly with COVID-19 inactivated virus vaccine (CoronaVac) in Southeastern Brazil: an active surveillance study

Healthcare workers, the elderly and other vulnerable populations were the first to receive COVID-19 vaccines in public health programs. There were few vaccine safety data available on the elderly. This observational study aimed to evaluate the inactivated vaccine (CoronaVac) safety in the elderly, at the beginning of the vaccination program, in Sao Paulo city, Brazil. The elderly people that received CoronaVac at the Reference Center for Special Immunobiologicals (CRIE) or at home, administered by the Interdisciplinary Home Care Team (NADI) of the Hospital das Clinicas were invited to participate in this phase 4 observational study. The vaccination schedule included two CoronaVac doses 28 days apart. The information on solicited and unsolicited adverse events following immunization were collected by phone calls on days 4 and 8 after each vaccine dose. We enrolled 158 adults aged 65 to 101 years (mean of 84.1 years); 63.9% were females and 95.6% had chronic conditions, 21.5% had moderate or severe impairment in daily living activities; 34.2% were pre-frail and 19.6% were frail. We were able to contact 95.6% and 91.6% of the vaccinated people, after the first and second doses, respectively; 31.8% and 23.4% of the contacted participants reported some adverse events (AE) following the first and second doses, respectively. Pain at the injection site, fatigue, myalgia and headaches were the most frequent solicited AE. Most AE were mild to moderate. There were eight severe adverse events, but none of them were considered related to the vaccine. The CoronaVac was safe and well tolerated by these adults of advanced age with frailty and comorbidities

Preparação e caracterização de compósitos poliméricos baseados em amido termoplástico e materiais de alta área superficial: zeólita ZSM-5 e sílica coloidal Preparation and characterization of polymeric composites based on thermoplastic starch and high surface area materials: ZSM-5 zeolite and colloidal silica

Foram produzidas amostras de amido termoplástico (TPS) reforçadas com materiais de alta área superficial, com o intuito de verificar a variação nas propriedades do polímero, com especial enfoque na sua permeabilidade a vapor d'água. Foram utilizadas como carga a sílica coloidal (área superficial de 122,7 m²/g) e uma zeólita do tipo ZSM-5, produzida em laboratório (área superficial de 261,3 m²/g), em teores de 2 a 10% em massa. Os resultados demonstraram que a adição de ambos os materiais melhorou as propriedades mecânicas do TPS, embora nos maiores teores houve redução da qualidade das interfaces e dessas propriedades, principalmente para a ZSM-5. Em todos os casos a introdução da carga inorgânica reduziu a permeabilidade ao vapor d'água em até 20% quando comparada à permeabilidade do TPS, porém a melhor dispersão da sílica coloidal na matriz permitiu as maiores reduções, apesar da área superficial inferior.Compositions of thermoplastic starch (TPS) reinforced by high surface area materials were produced, intending to study the variation in polymer properties, focusing on the permeability to water vapor. Colloidal silica (surface area 122.7 m²/g) and a ZSM-5 zeolite (surface area 261.3 m²/g) were used, in loadings from 2 to 10% weight. The results demonstrated that the addition of both materials was favorable to the TPS mechanical properties, however in higher loadings the quality of polymer interfaces and these properties were negatively affected, especially for ZSM-5. In all the cases the inorganic particles reduced the permeability to water vapor in levels below 20% when compared to pure TPS, although the best dispersion of colloidal silica determined better reductions, despite its lower surface area