Recycled polyvinyl chloride microplastics: investigation of environmentally relevant concentrations on toxicity in adult zebrafish.

Recycled polyvinyl chloride (PVC) microplastics have been detected in the aquatic environment. These recycled microparticles contain chemicals that are released into the environment reaching different organisms. Although the problem of the presence of recycled PVC microparticles in the environment is evident, the toxicological consequences of this contaminant to exposed organisms remains to be better determined. The aim of this study was to investigate the toxicity attributed to exposure to environmentally relevant concentrations of recycled PVC microplastics in adult zebrafish (Danio rerio). The experimental groups were: negative control, vehicle control, positive control, and recycled microplastics (20 ± 5 µm) at 5, 10 or 20 µg/L. Zebrafish (D. rerio) were exposed to respective treatments for 96 hr. Locomotion and oxidative status parameters were measured and mortality recorded. The positive control group presented increased mortality rates and decreased locomotor activity. Animals from the vehicle group did not show marked differences. Finally, no significant disturbances were found in survival rate, locomotion pattern and oxidative status of animals exposed to recycled PVC microparticles at 5, 10 or 20 µg/L. Taken together our results suggest that recycled PVC microplastics in this particle size range do not appear to exert harmful effects on exposed adult D. rerio. However, these results need to be carefully observed due to limitations including size of particle and duration of exposure parameters that might affect ecological consequences. It is suggested that additional studies applying other particles sizes and chronic exposure are needed to more comprehensively verify the toxicity of the contaminant investigated here.

Microbiological, thermal and mechanical performance of cellulose acetate films with geranyl acetate.

The present work concerns to investigate the microbiological, thermal and mechanical behavior of cellulose acetate films obtained with addition of 0.5 % (v/v) and 1.0 % (v/v) of geranyl acetate by the casting technique. The antimicrobial activities of the polymeric films were assessed against Staphylococcus aureus and Escherichia coli bacteria and against Aspergillus flavus fungal. The achieved results show that the films presented antibacterial and antifungal activities. Moreover, the incorporation of the geranyl acetate in the polymeric films was confirmed by FTIR and TGA technique, while DSC analysis pointed out the compatibility between the geranyl acetate and cellulose acetate. The addition of the geranyl acetate did not modify the mechanical behavior of the cellulose acetate films concerning stiffness and tensile strength. These results suggest that this new material is promising for future applications in biomedical devices and food packaging.

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.

Antifungal Activity and Acute and Repeated-Dose Toxicity Study of Geranyl Cinnamate Ester in Mice.

In the present study, the antifungal activity and toxicity of the geranyl cinnamate ester (GCE) were investigated. The GCE showed antifungal activity at a minimum concentration of 0.16 µL/mL against Candida albicans and at concentrations greater than 2.5 µL/mL against Aspergillus niger. In acute toxicity studies, the administration of GCE (2.000 mg/kg) affected the body weight gain and food intake but did not induce the mortality of the animals studied. After the investigation of repeated-dose toxicity of GCE at 2 and 4 mg/kg, the hematological and biochemical parameters were changed. In addition, the adrenal weight of male mice treated with GCE at 4 mg/kg was affected. In conclusion, according to the Organization for Economic Cooperation and Development (OECD) acute toxicity parameters, the geranyl cinnamate ester can be classified into safety category number 5. The results of this study suggested that the geranyl cinnamate ester may be a source of natural antifungals.

Estudo da atividade metanogênica específica de diferentes lodos anaeróbios / Study of specific methanogenic activity of different anaerobic sludges

RESUMO O estudo da atividade metanogênica específica (AME) constitui uma importante ferramenta para o controle operacional de reatores anaeróbios, pois apresenta parâmetros de monitoramento da eficiência e estabilidade de um reator biológico. Nesse sentido, o presente trabalho visou determinar a AME de lodos provenientes de reatores anaeróbios de fluxo ascendente (UASB - upflow anaerobic slugde blanket) de duas indústrias cervejeiras (lodos A e B), uma de processamento de grãos (lodo C), uma leiteira (lodo D) e uma de processamento de couro (lodo E). Os ensaios foram conduzidos em batelada, em ambiente aclimatado a 35°C, utilizando um equipamento para monitorar a geração de biogás em função do tempo de digestão. Também foi realizada a qualificação do gás metano presente no biogás gerado pelos diferentes lodos. O maior valor de AME obtido e a maior porcentagem do gás metano produzido, para uma concentração de biomassa de 5,0 gSTV.L-1 e 4,0 gDQO.L-1 de glicose, foram para o lodo B: 0,36 gDQO-CH4.gSTV-1.d-1 e 58,9%, respectivamente.

ABSTRACT The study of Specific Methanogenic Activity (SMA) is an important tool for operational control of anaerobic reactors, as it presents parameters to monitor the efficiency and stability of a biological reactor. For this reason, the present article aimed to determine the SMA of sludges from UASB reactors, of two different brewing industries (sludges A and B), a grain processing industry (sludge C), a dairy industry (sludge D), and a leather processing industry (sludge E). Assays were performed in batch, at an acclimatized environment (35°C), using a device equipment to monitor the generation of biogas due to digestion time. Also, the quantity of methane gas was measured in the biogas generated by the different sludges. The best SMA value obtained and the greater percentage of methane gas generated, with a biomass concentration of 5.0 gSTV.L-1, and a glucose concentration of 4.0 gCOD.L-1, were for sludge B, with 0.36 gCOD-CH4.gSTV-1.d-1 and 58.9%, respectively.

UHMWPE/HA biocomposite compatibilized by organophilic montmorillonite: An evaluation of the mechanical-tribological properties and its hemocompatibility and performance in simulated blood fluid.

The low interaction between ultra high molecular weight polyethylene (UHMWPE) and hydroxyapatite (HA) has been one of the problems that results in a composite material with low mechanical and tribological performance due to the formation of agglomerates and microstructural defects. These properties affect the quality of the material when used for total joint implants and other applications in hard tissue engineering. This study investigated the effect of the addition of organophilic bentonite (BO) into the interface HA and UHMWPE. The composite was prepared by wet milling in a planetary mill and then by compression molding. The composites samples were characterized by XRD, FTIR, SEM and DSC. The tensile and tribological mechanical properties were also evaluated. Furthermore, in vitro degradation using simulated blood fluid (SBF) and hemocompatibility was performed. The results suggest that the addition of 10 wt% of organophilic bentonite improved the interface between the UHMWPE and HA by exfoliation/intercalation, presenting the best results of modulus of elasticity, tensile strength, coefficient of friction and rate of wear. The composite UHMWPE/HA/BO-10 wt% presented low water absorption and induced the growth of apatite crystals on its surface. Additionally, its hemocompatibility index is within normal limits and induced a low adhesion and agglomeration of platelets in contact with human blood, evidencing that the UHMWPE/HA/BO-10 wt% composite is promising for application in bone tissue engineering.

Encapsulation of geranyl cinnamate in polycaprolactone nanoparticles.

Geranyl cinnamate is an ester derived from natural compounds that has excellent antibacterial properties but is susceptible to degradation in the presence of oxygen, light, heat, moisture and other aggressive agents, making it unstable. In this work, the encapsulation of geranyl cinnamate in polycaprolactone (PCL) nanoparticles and its antibacterial properties towards Escherichia coli and Staphylococcus aureus were investigated. PCL nanoparticles loaded with geranyl cinnamate were obtained by a miniemulsification/solvent evaporation technique resulting in spherical nanoparticles with an average diameter of 177.6 nm. TGA showed that geranyl cinnamate evaporation was retarded at 20 °C after encapsulation. Aqueous dispersions of geranyl cinnamate-loaded PCL nanoparticles stored at 4 °C presented good colloidal stability over 60 days. Minimum inhibitory concentration (MIC) tests showed that geranyl cinnamate was not released from the PCL nanoparticles in aqueous solution even after 72 h, requiring the use of a trigger (e.g. oil phase, lipase to degrade the polymer matrix) to release the active compound.

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.