RESUMEN: El río Tumbes es la principal fuente de agua de la ciudad del mismo nombre en el noroeste del Perú. Sin embargo, en las condiciones actuales recibe la influencia de actividades como la minera artesanal en la parte alta de la cuenca, contaminándolo con metales pesados como el plomo, el cual es potencialmente causante de enfermedades. Por otro lado, el sillar (ignimbrita) es un material de construcción extraído en la ciudad de Arequipa que en el momento de ser cortado en bloques causa un material residual que normalmente es desechado. El objetivo de esta investigación es producir y caracterizar materiales adsorbentes basados en sillar para remover directamente Pb del agua del río Tumbes. El sillar se llevó a tamaños de partícula de 150 µm y 250 µm, y fueron activados por pirolisis lenta con y sin presencia de ZnCl2, para luego ser impregnadas con nanopartículas (NPs) de ZnO utilizando la técnica de impregnación in situ. El tratamiento térmico logro modificar la estructura de los materiales, aumentando la fase cristalina de los mismos, sin embargo, aparentemente la concentración de NPs de ZnO impregnada sobre las muestras de sillar pirolizado fue muy reducida para ser detectada por difracción de rayos X. En las pruebas de cinética de adsorción de Pb utilizando directamente de muestras de agua del rio Tumbes, se demostró que los adsorbentes basados en sillar presentaron limitada capacidad de adsorción comparada con otros adsorbentes derivados de rocas, obteniendo valores de adsorción de entre 0,009 - 0,017 mg de Pb/g del adsorbente. Sin embargo, las concentraciones finales luego de los experimentos de adsorción se encentraron por debajo del límite de 0,05 mg/l establecido por la OMS para el caso de agua potable. A pesar de ello es importante el estudio a mayor profundidad con diversos tipos de sillar y otros tipos de modificaciones para corroborar el potencial uso del sillar como adsorbente.

ABSTRACT: Tumbes River is the main source of water for the city of the same name in northwest Peru. However, under current conditions it is negatively affected by activities such as artisanal mining in the upper part of the basin. It causes water pollution with heavy metals such as lead, which is potentially a cause of chronic diseases. On the other hand, ignimbrite is a volcanic rock extracted in the city of Arequipa. It is used as construction material and when it is cut into blocks, produces residual material that is normally discarded. This research aimed to produce and characterize adsorbent materials based on ignimbrite to directly remove Pb from the water of the Tumbes River. The ignimbrite was used in particle sizes of 150 µm and 250 µm, and the materials were activated by slow pyrolysis with and without the presence of ZnCl2. Then thermal treatment, the materials were impregnated with ZnO nanoparticles (NPs) using the in-situ impregnation technique. The thermal treatment manages to modify the structure of the materials, increasing their crystalline phase; however, apparently the concentration of ZnO NPs impregnated on the pyrolyzed ignimbrite samples was too low to be detected by X-ray diffraction. In the Pb adsorption kinetic tests using water samples directly from the Tumbes River, it is shown that adsorbents based on ignimbrite showed limited adsorption capacity compared to other adsorbents derived from rocks, obtaining adsorption values between 0.009 - 0.017 mg of Pb/g of the adsorbent. However, the final concentrations after the adsorption experiments were below the limit of 0.05 mg/l established by the WHO for drinking water. Despite this, it is important to conducted experiments using other types of ignimbrite and other types of modifications to corroborate the potential use of ignimbrite as an adsorbent.

Abstract The effect of graphene oxide (GO) on the concrete quality and the corrosion resistance of carbon steel reinforcement was evaluated. The concrete mix was calculated at a ratio of 1: 1.86: 2.14: 0.46 (cement: sand: gravel: water); the dosages of GO were 0.03 wt.% and 0.05 wt.% and the superplasticizer (PC) concentration was 0.6 wt.% concerning the cement mass. Compressive strength tests (7, 28, and 91 days), water absorption tests, determination of voids index (WATIDVI), ultrasonic pulse velocity (UPV) testing, and optical microscopy analysis were carried out. All concrete samples showed excellent compactness and low porosity. Open circuit potential measurements and linear polarization resistance (LPR) were performed during 15 cycles of partial immersion and drying of concrete in a 3.5 wt.% NaCl solution. A beneficial effect of 0.03 wt.% of GO addition on the corrosion resistance of the reinforced concrete was identified in the saline medium and the corrosion inhibition efficiency obtained was 79.3%.

ABSTRACT Segmentation is one of the inferential applications for detecting patterns in digital images, which has been widely used in the health area. Thresholding, a type of segmentation, consists of separating the gray groups of an image, through one or more thresholds applied to the histogram. Thus, we used the gray tone with the lowest Fuzzy Divergence found to apply the enhancement method, through membership values. This paper presents a method to assist physicians in interpreting lung radiography images, especially in the pandemic caused by COVID-19, when enhancing lung images. In addition, we consulted with a group of medical experts who saw an improvement in image quality, providing the perception of detail in the enhanced image compared to the original image.

Abstract In this work we study the effects of Initial State Radiation (ISR) and Beamstrahlung (BS), in the production of Z’ in the 3-3-1 model with heavy leptons. The impact of the ISR and BS on precision measurements strongly afects the behaviour of the production cross section around the resonance points: m Z ' = 5976.43 ( 6830.21 ; 8539.47 ) GeV for v χ = 3.5 ( 4.0 ; 5.0 ) TeV, at the Compact Linear Collider (CLIC).

Abstract The development of three-dimensional matrices for microbial cultures is a promising strategy by mimic the natural environments of cells and promoting adhesion, growth and cellular proliferation. In the current study, polyvinyl alcohol (PVA) foams were produced by the combination of gas foaming and freeze-drying for applied as microorganism 3D matrix. The spectra FTIR indicated consume of hydroxyl groups that evidences the crosslinking reaction and promoted increases in thermal stability. Morphological analysis by SEM revealed an interconnected porous structure in the PVA foams. Besides, the crosslinking reaction did not affect pore size and morphology. Meanwhile, cross-linked PVA foam (G-PVAFL) exhibited an increase of compressive modulus and compressive strength. The swelling ratio reached 85% and degradation kinetics of G-PVAFL showed a suitable profile to support microorganism in the biofilm formation. Escherichia coli (Gram-negative bacteria), Staphylococcus aureus (Gram-positive bacteria) and Candida albicans (yeast) were efficiently immobilized in G-PVAFL. In addition, cells morphology were preserved for all species investigated. Besides, Sugar Fermentation Test with Escherichia coli immobilized indicates the preservation of proliferative and metabolic activity. These results indicate that G-PVAFL is suitable as a matrix for 3D microbiological culture.

Abstract Concrete used in civil engineering is a composite obtained from the combination of coarse and fine aggregates, cement and water, and its cost and quality are normally associated to the proportion of its constituents (ceramic formulation), as well as the reduction of water consumption. The aggregates used in concrete may have diverse origins, and the syenite extracted at Pedra Branca Alkaline Massif is one of the materials that can be used for this substitution. In order to do so, a reference formulation of concrete was calculated and optimized using the mathematical models of Andreasen, and syenite was added substituting 25, 50, 75 and 100% of the fine aggregate. In order to maintain the original granulometric distribution, an algorithm was developed to compensate the different particle size distributions. The grain size correction guaranteed the maintenance of the original properties of the concrete, reaching values of mechanical strength above 35 MPa.

RESUMO: O objetivo deste estudo foi avaliar a eficácia de glyphosate, 2,4-D e diquat no controle das macrófitas aquáticas Brachiaria subquadripara, Hedychium coronarium e Myriophyllum aquaticum em condições de casa de vegetação. Utilizaram-se os seguintes herbicidas e doses: glyphosate a 240, 720, 1.680, 2.640, 3.600 e 4.320 g e.a. ha-1; 2,4-D a 335, 1.005, 1.675, 2.345 e 3.015 g e.a. ha-1; e diquat a 100, 200, 300, 400, 500 e 600 g i.a. ha-1 e um controle, com dez repetições. As pulverizações foram efetuadas com um pulverizador costal à pressão constante de CO2 de 172,36 KPa, ponta DG11002 e consumo de calda de 200 L ha-1. A eficácia de controle foi avaliada visualmente aos 3, 7, 15, 21, 30, 45 e 60 dias após a aplicação (DAA), e o acúmulo de massa seca, aos 60 DAA. O glyphosate promoveu a melhor eficácia, com 100% de controle de B. subquadripara e sem acúmulo de massa seca, a partir de 720 g e.a. ha-1. O 2,4-D apresentou o melhor controle para M. aquaticum, com 100% a partir 1.209 g e.a. ha-1, e para H. coronarium, com 99% de controle a partir de 2.015 g e.a. ha-1, ambas as doses sem o acúmulo de massa seca. O diquat não foi eficaz no controle das plantas de M. aquaticum e B. subquadripara, além de permitir rebrotas.

ABSTRACT: The aim of this study was to evaluate the effectiveness of glyphosate, 2,4-D, and diquat to control the aquatic macrophytes Brachiaria subquadripara, Hedychium coronarium, and Myriophyllum aquaticum under greenhouse conditions. The following herbicides and doses were used: glyphosate at 240, 720, 1,680, 2,640, 3,600, and 4,320 g a.e. ha-1, 2,4-D at 335, 1,005, 1,675, 2,345, and 3,015 g a.e. ha-1, diquat at 100, 200, 300, 400, 500, and 600 g a.i. ha-1, and a control with 10 replications. Sprayings were applied with a CO2-pressurized backpack sprayer at a constant pressure of 172.36 KPa, tips DG 11002, and spray solution consumption of 200 L ha-1. The effectiveness of control was evaluated visually at 3, 7, 15, 21, 30, 45, and 60 days after application (DAA) and dry matter accumulation at 60 DAA. Glyphosate promoted the best effectiveness, with 100% control of B. subquadripara, with no dry matter accumulation from 720 g a.e. ha-1. The herbicide 2,4-D presented the best control for M. aquaticum with 100% control from 1,209 g a.e. ha-1, and for H. coronarium with 99% control from 2.015 g a.e. ha-1, both doses with no dry matter accumulation. The diquat was not effective in controlling the plants of M. aquaticum and B. subquadripara, besides allowing resprouts.

RESUMO: Os objetivos deste estudo foram estabelecer o cultivo massal de W. brasiliensis em condição de laboratório, determinar a sensibilidade para as substâncias-referência (dicromato de potássio, cloreto de sódio e cloreto de potássio) e a estimar a toxicidade aguda (CL50;7d) para os herbicidas glyphosate, diquat, paraquat, imazapyr, 2,4-D, saflufenacil, imazamox, penoxsulam, metsulfuron-methyl e atrazine. Para estabelecimento do cultivo, foram testados três meios: Hoagland’s; 5,0 g L-1 de fertilizante NPK (20;5;20) e o da mistura Latossolo Vermelho + substrato orgânico de planta aquática em decomposição (2:1; v v-1). Após o estabelecimento do cultivo, foram realizados os ensaios de sensibilidade com as substâncias-referência e os ensaios de toxicidade aguda para os herbicidas. A W. brasiliensis apresentou excelente resposta de sensibilidade às substâncias-referência com CL50;7d média de 15,61±2,13 g L-1 para o cloreto de sódio, de 17,02±0,50 g L-1 para o cloreto de potássio e de 52,54±4,27 mg L-1 para o dicromato de potássio. A resposta de toxicidade aguda de W. brasiliensis para o diquat (CL50;7d = 0,07 mg L-1) e paraquat (< 0,05 mg L-1) indica que a planta pode ser considerada extremamente sensível; para o imazapyr, sensível (CL50;7d = 21,10 mg L-1), e para os demais herbicidas testados, pouco sensível. A capacidade de resposta relativa a diferentes grupos de herbicidas somada à resposta padronizada às substâncias-referência e facilidade de cultivo em laboratório indicam potencial para o uso desta planta aquática na avaliação de risco de herbicidas em ambientes aquáticos.

ABSTRACT: This study aimed to establish the mass cultivation of Wolffia brasiliensis under laboratory conditions, determine the sensitivity of reference substances (potassium dichromate, sodium chloride, and potassium chloride), and estimate the acute toxicity (LC50;7d) for the herbicide glyphosate, diquat, paraquat, imazapyr, 2,4-D, saflufenacil, imazamox, penoxsulam, metsulfuron-methyl, and atrazine. Three media were tested for culture establishment: Hoagland’s medium, 5.0 g L-1 NPK fertilizer (20-5-20), a mixture of Oxisol + organic substrate of decaying aquatic plant (2:1; v v-1). Sensitivity tests with reference substances and acute toxicity for herbicides were carried out after establishing the cultivation. The species W. brasiliensis presented an excellent sensitivity response to reference substances, with means of LC50;7d of 15.61±2.13 g L-1, 17.02±0.50 g L-1, and 52.54±4.27 mg L-1 for sodium chloride, potassium chloride, and potassium dichromate, respectively. The acute toxicity response indicated that W. brasiliensis was extremely sensitive to diquat (LC50;7d = 0.07 mg L-1) and paraquat (LC50;7d < 0.05 mg L-1), sensitive to imazapyr (LC50;7d = 21.10 mg L-1), and little sensitive to the other herbicides. The response capacity for the different groups of herbicides, the standardized response to reference substances, and ease of cultivation in the laboratory indicate the potential for using this aquatic plant in the assessment of herbicide risk in aquatic environments.

RESUMO: Neste estudo foi avaliada a eficácia do imazamox para controle de E. crassipes, com bico de pulverização de energia centrífuga em doses e volumes de calda de pulverização e comparação do custo de controle mecânico e químico de plantas aquáticas. Foram utilizadas as doses de 200, 400 e 600 g i.a. ha-1 de imazamox e volumes de calda de 25, 50 e 100 L ha-1, além de um controle (sem aplicação do herbicida), com dez repetições. As aplicações foram feitas com bico de pulverização de energia centrífuga. As avaliações foram realizadas por porcentagem de controle em 7, 15, 21 e 30 dias após a aplicação (DAA), e a massa seca das plantas foi mensurada aos 30 DAA, assim como a retenção foliar das caldas de pulverização. Aos 30 DAA, em 200, 400 e 600 g i.a. ha-1 e 50 L ha-1, ocorreu eficácia de 96% a 100% e redução da massa seca das plantas de 88% a 100%. As doses e volumes de calda do imazamox foram eficazes no controle de E. crassipes, exceto 200 g i.a. ha-1 e 25 L ha-1. A maior retenção foliar do aguapé foi de 0,010 mL cm² na concentração de 400 g i.a. ha-1 e 50 L ha-1. O custo do controle químico foi 20 vezes menor que o mecânico, o que o torna economicamente mais viável que este. Esses resultados são importantes para a tomada de decisão sobre qual método e tecnologia de aplicação devem ser utilizados no controle de E. crassipes.

ABSTRACT: The efficacy of imazamox to control Eichhornia crassipes with a centrifugal energy spray nozzle at doses and volumes of spray solution and the costs of mechanical and chemical control of aquatic plants were evaluated in this study. Imazamox doses consisted of 200, 400, and 600 g a.i. ha-1, and spray solution volumes consisted of 25, 50, and 100 L ha-1, with a control (without herbicide application) and ten replications. Applications were performed with a centrifugal energy spray nozzle. The evaluations were carried out considering the percentage of control at 7, 15, 21, and 30 days after application (DAA), and plant dry matter was measured at 30 DAA, as well as leaf retention of spray solutions. An efficacy from 96 to 100% and plant dry matter reduction from 88 to 100% was observed at 30 DAA using imazamox doses of 200, 400, and 600 g a.i. ha-1 and a spray solution volume of 50 L ha-1. Imazamox doses and spray solution volumes were effective in controlling E. crassipes, except for 200 g a.i. ha-1 and 25 L ha-1, respectively. The highest leaf retention of E. crassipes was 0.010 mL cm2 at an imazamox dose of 400 g a.i. ha-1 and volume of 50 L ha-1. The cost of chemical control was 20 times lower when compared to mechanical control, making it economically more viable. These results are important for decision-making on which method and application technology should be used to control E. crassipes.

CONTEXTO: El ambiente universitario puede a menudo favorecer el desarrollo de problemas de salud mental, ya que los universitarios son sometidos a intenso nivel de estrés y carga cognitiva. OBJETIVO: Verificar la influencia de la religiosidad en la satisfacción con la vida y en la adopción de estrategias para lidiar con los problemas. MÉTODOS: Estudio cuantitativo con recolección de datos utilizando instrumentos psicométricos validados con 588 estudiantes universitarios de 18 a 63 años. Se utilizó la técnica de modelado de ecuaciones estructurales para verificar un modelo de influencia. RESULTADOS: Los resultados indican que la Religiosidad influye positivamente y de forma significativa en la Satisfacción con la Vida, así como la adopción de Estrategias para Enfrentamiento de Problemas. Los resultados no son generalizables, sin embargo constituyen evidencia empírica de la importancia de la religiosidad en términos de salud mental. CONCLUSIÓN: En general, esta investigación pretendió verificar un modelo teórico sistémico, el cual hipotetizaba una interdependencia entre las variables Religiosidad, Coping y Satisfacción con la vida; con ello, no sólo se comprobó el modelo pretendido, pero, se cree que los resultados observados, teóricamente, sostienen las propuestas sugeridas por la psicología positiva.

BACKGROUND: The university environment can often favor the development of mental health problems, since university students are subjected to intense levels of stress and cognitive load. AIM: To verify the influence of religiosity on satisfaction with life and on the adoption of strategies to deal with problems. METHODS: Quantitative study with data collection using validated psychometric instruments with 588 university students aged 18 to 63 years. The structural equation modeling technique was used to verify an influence model. RESULTS: The results indicate that Religiosity influences positively and significantly the Satisfaction with Life, as well as the adoption of Strategies to Confront Problems. The results are not generalizable, however they constitute empirical evidence of the importance of religiosity in terms of mental health. CONCLUSION: In general, this research aimed to verify a systemic theoretical model, which hypothesized an interdependence between the variables Religiosity, Coping and Satisfaction with life; Thus, not only has the desired model been proved, but it is believed that the results observed theoretically support the proposals suggested by positive psychology.

CONTEXTO: O ambiente universitário pode muitas vezes favorecer o desenvolvimento de problemas de saúde mental, uma vez que os universitários são submetidos a intenso nível de estresse e carga cognitiva. OBJETIVO: Verificar a influência da religiosidade na satisfação com a vida e na adoção de estratégias para lidar com os problemas. MÉTODOS: Estudo quantitativo com coleta de dados utilizando instrumentos psicométricos validados com 588 estudantes universitários de 18 a 63 anos. Foi utilizada a técnica de modelagem de equações estruturais para verificar um modelo de influência. RESULTADOS: Os resultados indicam que a Religiosidade influencia positivamente e de forma significativa a Satisfação com a Vida, bem como a adoção de Estratégias para Enfrentamento de Problemas. Os resultados não são generalizáveis, entretanto constituem evidência empírica da importância da religiosidade em termos de saúde mental. CONCLUSÃO: De forma geral, esta pesquisa pretendeu verificar um modelo teórico sistêmico, o qual hipotetizava uma interdependência entre as variáveis Religiosidade, Coping e Satisfação com a vida que se comprovou. Com isso, acredita-se que os resultados observados, teoricamente, sustentam as propostas sugeridas pela psicologia positiva.

Resumo O porcelanato é um tipo de placa cerâmica de revestimento que vem se destacando atualmente por apresentar boas propriedades estéticas, como a superfície decorada, e mecânicas, como a baixa absorção de água e elevada resistência mecânica e ao ataque químico. As matérias-primas utilizadas para a produção de porcelanato são principalmente a argila e o feldspato. O feldspato é uma das matérias-primas responsáveis pela sinterização durante a queima e auxilia no desenvolvimento de baixa porosidade e elevada resistência ao desgaste da peça cerâmica. Porém, o Brasil apresenta reservas de feldspato em regiões distantes dos centros produtores, fato que encarece a produção deste produto. Dessa forma surge como alternativa a utilização de nefelina para substituir o feldspato, total ou parcialmente, pois este mineral apresenta características bastante similares. Para verificar a influência de tal substituição nas propriedades do porcelanato, inicialmente foi necessário realizar o estudo das propriedades reológicas e físicas da suspensão utilizada na produção. Os resultados encontrados mostraram que a viscosidade da suspensão tende a aumentar com a adição de nefelina, assim como a densidade aparente da peça após a queima.

Abstract The porcelain is a type of ceramic tile which has been contrasted for its good aesthetical, such as decorated surface, and mechanical properties, such as low water absorption and high mechanical and chemical attack resistance. The raw materials used for porcelain tiles production are mainly clay and feldspar. Feldspar is one of the raw materials responsible for the sintering during firing and it helps on the development of low porosity and high wear resistance of the ceramic piece. However, Brazil presents feldspar sources in regions distant from production centers, leading to higher cost for the porcelain tiles production. Thus, nepheline is thought as an alternative to substitute feldspar, totally or partially, since this mineral presents very similar characteristics. In order to verify the influence of this substitution to the properties of the porcelain tiles, it was necessary initially to study the influence of nepheline addition in both rheological and physical properties of the suspension. The results showed that the viscosity of the suspension increases with the addition of nepheline, as well as the apparent density of the fired piece.

RESUMO: O objetivo deste estudo foi avaliar a aplicação do herbicida glyphosate acrescido de três adjuvantes e três pontas de pulverização no controle da macrófita Pistia stratiotes. Para isso, após a colonização de 80 a 90%, foi realizada a aplicação de 1,5, 3,5 e 7,0 L ha-1 de glyphosate isolado e com os adjuvantes Aterbane® BR, Veget’oil® e Dash® HC (0,5% vv-1) e pontas de pulverização (AI 110.02, TTI 110.015 e TT 110.015) e um controle (água). As aplicações foram feitas com pulverizador costal pressurizado de precisão, à pressão constante de 50 p.s.i. e consumo de calda de 200 L ha-1. Na dose de 1,5 L ha-1 houve 100% de controle para a combinação glyphosate + Veget’oil + a ponta AI 110.02 (Gly+V.oil+AI), Gly+Aterb.+TTI e Gly+Dash+TT em 15 dias após aplicação (DAA). Em 3,5 L ha-1 o maior controle (95%) foi para Gly+AI, Gly+Aterb.+TTI, Gly+V.oil+TTI, Gly+Dash+TTI, Gly+Aterb.+TT e Gly+Dash+TT, e em 7,0 L ha-1 chegou-se a 100% para Gly+AI, Gly+Aterb.+AI, Gly+V.oil+AI, Gly+Aterb.+TTI, Gly+V.oil+TTI, Gly+Dash+TTI, Gly+TT e Gly+Dash+TT. Assim, conclui-se que em 1,5 L ha-1 a combinação de glyphosate com o Dash® e a ponta TT 110.015 (Gly+Dash+TT) foi a mais promissora; em 3,5 L ha-1 foi Gly+Aterb.+TTI e em 7,0 L ha-1 as pontas com indução de ar (AI 110.02 e TTI 110.015), independentemente de o glyphosate estar isolado ou com qualquer um dos três adjuvantes, foram as melhores no estabelecimento do controle.

ABSTRACT: The goals of this study were to evaluate the application of glyphosate plus three adjuvants and three spray nozzles in controlling the macrophyte Pistia stratiotes. For this purpose, after an 80 to 90% colonization, the application of 1.5, 3.5 and 7.0 L h-1 of isolated glyphosate and with the adjuvants Aterbane® BR, Veget’oil® and Dash® HC (0.5% vv-1) and the spray nozzles (AI 110.02, TTI 110.015 and TT 110.015) was performed, plus a control sample (water). Applications were performed with a pressurized backpack precision sprayer, at the constant pressure of 50 p.s.i. and with mixture consumption of 200 L ha-1. At the dose of 1.5 L ha-1, there was 100% control for the combination glyphosate + Veget’oil + tip AI 110.02 (Gly+V.oil+AI, Gly+Aterb.+TTI and Gly+Dash+TT) 15 days after application (DAA). At 3.5 L ha-1, the greatest control (95%) was with Gly+AI, Gly+Aterb.+TTI, Gly+V.oil+TTI, Gly+Dash+TTI, Gly+Aterb.+TT and Gly+Dash+TT; and at 7.0 L ha-1 100% was observed for Gly+AI, Gly+Aterb.+AI, Gly+V.oil+AI, Gly+Aterb.+TTI, Gly+V.oil+TTI, Gly+Dash+TTI, Gly+TT and Gly+Dash+TT. Thus, it is possible to conclude that at 1.5 L ha-1, the combination of glyphosate plus Dash® and with the nozzle TT 110.015 (Gly+Dash+TT) was the most promising one; at 3.5 L ha-1, it was Gly+Aterb.+TTI and at 7.0 L ha-1 the air induction nozzles (AI 110.02 and TTI 110.015), whether with isolated glyphosate or with any of the three adjuvants, were the best at providing control.

RESUMO O objetivo deste estudo foi avaliar a eficácia do diquat isolado e em mistura com fontes de cobre (hidróxido e oxicloreto) para o controle da macrófita submersa Hydrilla verticillata e da microalga A. gracilis. Para isso, foram utilizados ponteiros com 10,0 cm de H. verticillata e 300 mL de cultura de A. gracilis. Os experimentos foram conduzidos em laboratório, e as concentrações de diquat testadas foram: 0,1; 0,2; 0,4; 0,8; 1,2; e 1,8 mg L-1 isoladas ou acrescidas de 1,0% de oxicloreto de cobre e de hidróxido de cobre, além de um controle. Aos 3, 7, 11, 21 e 30 dias após aplicação foram avaliados os sinais visuais de fitotoxicidade, e aos 60 dias após aplicação foi mensurada a produção de biomassa fresca e seca e o comprimento das plantas. Aos 1, 7, 15, 21, 30, 45 e 60 dias após aplicação foi avaliada a concentração de clorofila a presente na água. O herbicida diquat utilizado de forma isolada ou em mistura com as fontes de cobre oxicloreto e hidróxido foi efetivo no controle de H. verticillata e da microalga A. gracilis.

ABSTRACT The goal of this study was to evaluate the effectiveness of diquat, both isolated and associated with copper sources (oxychloride and hydroxide) in controling the H. verticillata submerged macrophyte and the A. gracilis microalgae. For this purpose, 10.0 cm H. verticillata young branches and 300 mL of A. gracilis culture were used. The experiments were performed in laboratory and the tested diquat concentrations were: 0.1; 0.2; 0.4; 0.8; 1.2; and 1.8 mg L-1, either isolated or added with 1.0% copper oxychlorideand hydroxide, as well as a control sample. On day 3, 7, 11, 21 and 30 after application, phytotoxicity signs were evaluated and on day 60 after application, green and dry biomass production and plant length were measured. To obtain dry mass, plants remained in a greenhouse with forced air circulation at 65.0 oC, until constant weight. On day 1, 7, 15, 21, 30, 45 and 60 after application, the concentration of chlorophyll a in the water was assessed. The herbicide diquat used alone or in combination with sources copper oxychloride and hydroxide was effective in the control of H. verticillata and microalgae A. gracilis.

RESUMO: O objetivo deste estudo foi avaliar o efeito de subdoses dos herbicidas 2,4-D e clomazone no crescimento das macrófitas submersas Egeria densa e E. najas, em condição de microensaio. Para isso, os ensaios foram conduzidos em sala de bioensaio com temperatura de 27,0 ± 2,0 oC, fotoperíodo de 24 horas de luz e iluminação de 500 lux. Os fragmentos apicais (ponteiros) das macrófitas com 5,0 cm de comprimento foram transferidos para tubos de ensaio com capacidade de 100 mL, contendo 70 mL de água. As concentrações testadas foram: 0,1; 1,0; 3,5; 11,2; 36,5; e 118,0 mg L-1, e um controle com sete repetições. No ensaio com 2,4-D, para E. densa, no controle e em 0,1 mg L-1 ocorreu menor comprimento; em 1,0, 3,5, 11,2, 36,5 e 118,0 mg L-1 ocorreu crescimento relativo de 90,6, 96,3, 91,6, 86,5 e 58,8%, demonstrando estímulo do crescimento. Para E. najas, o comportamento foi similar ao de E. densa. No ensaio com clomazone, para E. densa, o maior comprimento ocorreu no controle. Nas concentrações de 0,1; 1,0; 3,5; 11,2; 36,5; e 118,0 mg L-1 ocorreu crescimento relativo de -25,8; -26,4; -31,7; -28,4; -37,7; e -45,0%, respectivamente, demonstrando efeito herbicida para a planta. Quanto a E. najas, o comportamento foi similar, com os menores crescimento em 11, 2, 36,5 e 118,0 mg L-1. O herbicida 2,4-D, em subdoses, causa estímulo no crescimento (efeito hormese) de E. densa e E. najas, ao passo que o clomazone provoca efeito herbicida.

ABSTRACT: The goal of the study was to evaluate the effect of 2.4-D and clomazone doses on the growth of the submerged macrophytes Egeria densa and E. najas, in microassay conditions. Therefore, tests were conducted in a bioassay room at the temperature of 27.0 ± 2.0 °C, photoperiod of 24 light hours and illumination of 500 lux. The apical fragments (shoot tips) of the macrophytes with 5.0 cm of length were transferred to test tubes with a 100 mL capacity, containing 70 mL of water. The tested concentrations were: 0.1; 1.0; 3.5; 11.2; 36.5; and 118.0 mg L-1 and a control sample with seven replications. In the test with 2.4-D on E. densa, in the control sample treatment and the 0.1 mg L-1 treatment there was shorter length: at 1.0; 3.5; 11.2; 36.5 and 118.0 mg L-1 there was a relative increase of 90.6; 96.3; 91.6; 86.5 and 58.8%, demonstrating growth stimulation. E. najas behavior was similar to that of E. densa. In the test with clomazone for E. densa, the greatest length occurred in the control sample treatment. At the concentrations of 0.1; 1.0; 3.5; 11.2; 36.5 and 118.0 mg L-1, there was relative growth of -25.8; -26.4; -31.7; -28.4; -37.7 and -45.0% respectively, showing herbicidal effect on the plants. E. najas behavior was similar, with lower growth at 11.2, 36.5 and 118.0 mg L-1. Sub-doses of the herbicide 2.4-D cause growth stimulation (Hormesis effect) in E. densa and E. najas, while clomazone causes herbicidal effect.

RESUMO O objetivo deste estudo foi classificar o antibiótico Terramicina(r) de acordo com a toxicidade aguda e o risco de intoxicação ambiental para Oreochromis niloticus, Daphnia magna e Lemna minor, com base no seu ingrediente ativo oxitetraciclina (OTC). Além disso, observou-se a ocorrência de sinais de intoxicação aguda em peixes e o efeito da diluição do antibiótico sobre as variáveis de qualidade de água. Alevinos, neonatos e frondes foram expostos a concentrações de OTC. De acordo com os resultados dos testes de toxicidade aguda, a Terramicina(r) foi classificada pela toxicidade aguda e pelo risco de intoxicação ambiental. Para O. niloticus, a CL(I)50; 48h calculada foi de 6,92 mg L-1, para D. magna a CE(I)50; 48h foi de 0,17mg.L-1, enquanto para L. minor a CI(I)50;7d foi de 0,68 mg L-1. A Terramicina(r) foi classificada como muito tóxica para O. niloticus e extremamente tóxica para D. magna e L. minor e causa risco de intoxicação ambiental para os três organismos testados. Concentrações de 7,5 e 8,0 mg L-1 de OTC reduziram a concentração de oxigênio dissolvido na água. De acordo com este estudo, a Terramicina(r) não deve ser utilizada na aquicultura, pois é altamente tóxica e causa risco de intoxicação ambiental aos organismos teste.

ABSTRACT The aim of this study was to classify the antibiotic Terramycin(r) according to acute toxicity and the environmental risk that it poses for Oreochromis niloticus, Daphnia magna, and Lemna minor based on its active ingredient oxytetracycline (OTC). In addition, the occurrence of acute poisoning signs in fish and antibiotic dilution effect in the water quality variables were observed. For this purpose, fingerlings, neonates, and while were exposed to the concentrations of OTC. According to OTC acute toxicity test results, the Terramycin(r) was classified by acute toxicity and environmental poisoning risk classes. To O. niloticus, the calculated LC(I)50;48h was 6.92 mg L-1, for D. magna the EC(I)50;48h was 0.17 mg L-1, while for L. minor, IC(I)50;7d was 0.68 mg L-1. Terramycin(r) was classified as very toxic to O. niloticus, and highly toxic to D. magna and L. minor and cause risk of environmental poisoning for the three organismis tested. Concentrations of 7.5 and 8.0 mg L-1 OTC reduce the concentration of dissolved oxygen in the water. According to this study, Terramycin(r) should not be used in aquaculture, as it is highly toxic and causes risk of environmental toxicity test organisms.