Magnesium oxide nanoparticles and their ecotoxicological effect on edaphic organisms in tropical soil.

The demand for food has intensified production in agricultural areas and stimulated the use of nanotechnology to develop new inputs, especially nanoparticle materials. In this new context, predicting the impact of using nanoparticles on non-target organisms becomes a necessary measure. The aim of this study was to evaluate the ecotoxicological potential of magnesium (Mg2+ ) added via magnesium oxide nanoparticles (MgO-NPs), magnesium oxide (MgO), and magnesium nitrate hexahydrate (Mg [NO3 ]2 ·6H2 O) incubated over time in tropical soil on earthworms (Eisenia andrei), springtails (Folsomia candida), and enchytraeids (Enchytraeus crypticus). Tests were conducted using a clay-textured Latossolo Vermelho distrófico (Oxisol), which received increasing doses of Mg2+ (0; 25; 50; 100; 200 and 400 mg kg−1 of soil) from the three sources tested added to the soil. Treated soil was incubated for 120 days in a room with controlled temperature and photoperiod, and the ecotoxicological tests were performed at 0, 60, and 120 days of incubation. Despite having caused reduction in the reproduction of F. candida at the incubation time 0, MgO-NPs showed a low toxic potential against the other species studied, with toxicity only at a higher dose of 50 mg Mg kg−1 when compared to the other sources of Mg2+ applied to the soil (MgO and Mg [NO3 ]2 ·6H2 O). Responses associated with incubation times showed that all magnesium sources tested have lower toxicity over incubation time.

Study of phenol biodegradation in different agitation systems and fixed bed column: experimental, mathematical modeling, and numerical simulation.

Phenol degradation was studied in two different agitation systems in a batc h reactor (mechanical agitation and orbital agitation) and the support of the most efficient system was used for fixed bed bioreactor studies. The support used was coconut shell charcoal. The results showed that the mechanical agitation bioreactor was more effective in phenol removal, due to the amount of biomass adhered to the support (8.56 mg gsupport-1), running at approximately 100% of the phenol biodegradation in 300 min. The toxicity analysis of the waters was moderate, because the EC50,48h values in the analyzed samples are higher than 50%. Within the experimental data obtained from the batch system, it was possible to find the parameters of the kinetic model of Michaelis-Menten, which was used to simulate the bioreactor in a fixed bed. A mathematical model of a one-equation, which considers the effects of dispersion, convection, and reaction in the liquid phase, and diffusion and reaction inside the biofilm was used and the results obtained through numerical simulation were compared with the experimental results of the bioreactor in a fixed bed, and new operational conditions in the bed were simulated with good accuracy.

Avaliação da eficácia dos equipamentos de proteção individual para a exposição ocupacional ao frio / Evaluation of the efficacy of personal protective equipment against occupational exposure to cold

INTRODUÇÃO: Os setores climatizados, no ramo de indústrias alimentícias, apresentam variações de temperatura de -35 a 12ºC, as quais são necessárias para garantir a qualidade dos alimentos. Entretanto, essa faixa de temperatura pode ser um agente nocivo para a saúde dos trabalhadores. OBJETIVO:Estudar os parâmetros de exposição ocupacional ao risco frio para estimar o índice de isolamento térmico e determinar a eficácia dos equipamentos de proteção individual. MÉTODOS: Na primeira etapa foram avaliadas as variáveis ambientais (temperatura do ar, velocidade do ar, umidade relativa do ar) e a taxa de metabolismo; na segunda etapa foi determinado o índice de isolamento térmico fornecido; e na terceira etapa foi calculado o índice de isolamento básico de vestuário exigido para manter o equilíbrio térmico e verificada a eficácia dos equipamentos de proteção individual. RESULTADOS: Embora a temperatura do ar seja inferior nas atividades desenvolvidas no túnel de congelamento no setor de embalagem secundária, comparando com as atividades realizadas na câmara de estocagem de operar empilhadeira e transportar produtos, o índice de isolamento básico de vestuário exigido é maior nas atividades desenvolvidas com uso de empilhadeira, mesmo a temperatura sendo superior. Isso ocorre em função da velocidade do ar ser superior nas atividades realizadas nas empilhadeiras. CONCLUSÕES: Em 83,3% das atividades avaliadas a proteção se mostrou eficaz, porém, existe a possibilidade dos indivíduos sentirem desconforto térmico devido ao excesso de roupa fornecida. Apesar de a proteção ser insuficiente em 16,7%, as pausas de recuperação térmica eliminam o risco de hipotermia.

BACKGROUND: The temperature of climate controlled areas in the food industry varies from -35ºC to 12ºC to ensure the quality of food. However, this temperature range might be harmful to the health of workers. OBJECTIVE: To analyze parameters related to occupational exposure to cold risks to calculate clothing insulation indices and establish the efficacy of personal protective equipment (PPE). METHODS: In stage 1 we analyzed environmental variables (air temperature and velocity and relative humidity) and the metabolic rate; in stage 2 we calculated the resultant clothing insulation index; in stage 3 we calculated the basic clothing insulation required to maintain the thermal balance and investigated the efficacy of PPE. RESULTS: While the air temperature was lower for activities developed in the freezing tunnel (secondary packaging department), required basic clothing insulation was higher for activities involving operating forklifts. CONCLUSION: Protection was efficacious for 83.3% of the analyzed activities, however, occurrence of thermal discomfort cannot be ruled out as a function of excessive clothing. Although protection was insufficient for 16.7% of the analyzed activities, breaks for thermal recovery neutralized the risk of hypothermia.

Evaluation of the efficacy of personal protective equipment against occupational exposure to cold.

BACKGROUND: The temperature of climate controlled areas in the food industry varies from -35°C to 12°C to ensure the quality of food. However, this temperature range might be harmful to the health of workers. OBJECTIVE: To analyze parameters related to occupational exposure to cold risks to calculate clothing insulation indices and establish the efficacy of personal protective equipment (PPE). METHODS: In stage 1 we analyzed environmental variables (air temperature and velocity and relative humidity) and the metabolic rate; in stage 2 we calculated the resultant clothing insulation index; in stage 3 we calculated the basic clothing insulation required to maintain the thermal balance and investigated the efficacy of PPE. RESULTS: While the air temperature was lower for activities developed in the freezing tunnel (secondary packaging department), required basic clothing insulation was higher for activities involving operating forklifts. CONCLUSION: Protection was efficacious for 83.3% of the analyzed activities, however, occurrence of thermal discomfort cannot be ruled out as a function of excessive clothing. Although protection was insufficient for 16.7% of the analyzed activities, breaks for thermal recovery neutralized the risk of hypothermia.

INTRODUÇÃO: Os setores climatizados, no ramo de indústrias alimentícias, apresentam variações de temperatura de -35 a 12°C, as quais são necessárias para garantir a qualidade dos alimentos. Entretanto, essa faixa de temperatura pode ser um agente nocivo para a saúde dos trabalhadores. OBJETIVO: Estudar os parâmetros de exposição ocupacional ao risco frio para estimar o índice de isolamento térmico e determinar a eficácia dos equipamentos de proteção individual. MÉTODOS: Na primeira etapa foram avaliadas as variáveis ambientais (temperatura do ar, velocidade do ar, umidade relativa do ar) e a taxa de metabolismo; na segunda etapa foi determinado o índice de isolamento térmico fornecido; e na terceira etapa foi calculado o índice de isolamento básico de vestuário exigido para manter o equilíbrio térmico e verificada a eficácia dos equipamentos de proteção individual. RESULTADOS: Embora a temperatura do ar seja inferior nas atividades desenvolvidas no túnel de congelamento no setor de embalagem secundária, comparando com as atividades realizadas na câmara de estocagem de operar empilhadeira e transportar produtos, o índice de isolamento básico de vestuário exigido é maior nas atividades desenvolvidas com uso de empilhadeira, mesmo a temperatura sendo superior. Isso ocorre em função da velocidade do ar ser superior nas atividades realizadas nas empilhadeiras. CONCLUSÕES: Em 83,3% das atividades avaliadas a proteção se mostrou eficaz, porém, existe a possibilidade dos indivíduos sentirem desconforto térmico devido ao excesso de roupa fornecida. Apesar de a proteção ser insuficiente em 16,7%, as pausas de recuperação térmica eliminam o risco de hipotermia.

Microencapsulation of garlic oil by ß­cyclodextrin as a thermal protection method for antibacterial action.

The present study investigated the encapsulation process of garlic oil in ß­cyclodextrin (ßCD) and the antibacterial properties of the ßCD-garlic oil complex against Escherichia coli and Staphylococcus aureus. The encapsulation method increased the thermal stability of garlic oil with a formation constant (Kc) value of 253.78 L·mol-1 for of the ßCD-garlic oil complex, which confirmed the success of the encapsulation process. Scanning electron microscopy analysis showed that the dimensions of the structures formed by the inclusion complex of ßCD-garlic oil had values ranging from 5 to 10 µm. After thermal treatment of the ßCD-garlic oil complex at 60 °C for 1 h, the complex retained significant antibacterial action. The minimum inhibitory concentration (MIC) and agar diffusion results showed that the microcapsules containing 81.73 mmol·L-1 garlic oil exhibited excellent antibacterial action.