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Se estudió la capacidad de remoción de cromo (VI) en solución acuosa por la biomasa modificada del grano de arroz, utilizando el método colorimétrico de la difenilcarbazida, para evaluar la concentración del metal. Se evaluó la bioadsorción a diferentes pH´s (1, 2, 3 y 4) a diferentes tiempos. También se estudió el efecto de la temperatura en el intervalo de 28 a 60 °C y la remoción a diferentes concentraciones iniciales de Cr (VI) de 200 a 1 000 mg/l. La mayor remoción del metal fue a los ocho días, con un 100 y 79 %, para las biomasas modificada y no modificada, respectivamente, con un pH de 1.0, 28 °C y 1 g de biomasa. Con respecto a la temperatura de trabajo, la óptima fue de 60 °C, con un 100 % de remoción a los cinco días, mientras que a las concentraciones de cromo (VI) analizadas, la biomasa natural mostró una buena capacidad de remoción, eliminando 200 mg/l del metal a los 13 días y una temperatura de 28 °C. Además, a mayor concentración de la biomasa, es mayor la remoción del metal, y elimina eficientemente el metal de tierra y aguas residuales contaminadas (71 y 73 %, respectivamente), a los 10 días de incubación con 10 g de biomasa modificada.

Background and ObjectivesIn preparation for the suspected influx of COVID-19 patients, many healthcare systems reduced or discontinued provision of “non-urgent” care. This decision had potential impact on stroke prevention and management. We conducted a large population survey to assess the effect of mandatory social isolation on routine health controls, emergency consultations and other stroke care-related behaviors of the population during the pandemic.MethodsWe distributed multiple-choice anonymous questionnaires through the institutional email database and through the email database of clients of a beverage delivery company. Most respondents resided in the metropolitan area of Buenos Aires. This is the area where the infection rates were highest and restriction measures were hardest. The survey assessed demographic characteristics and actual and potential behaviors of people regarding medical checkups, risk factors control, medication provision and response to onset of symptoms consistent with stroke or TIA. Surveys were sent during May 2020, the strictest period of the quarantine in Argentina.ResultsA total of 10,303 questionnaires were completed. Thirty-seven percent of the respondents were older than 60 years, 74% were women and 16% lived alone. Vascular risk factors were present in 39% of the individuals. Seventy-six percent did not continue with their regular medical checkups during the mandatory social and preventive isolation, 21% had difficulty obtaining medical prescriptions and only 38% considered that health institutions had implemented reliable safety measures to avoid exposure to COVID-19. When asked about response in case of onset of stroke symptoms, 9% would not consult given the context of the pandemic. Six percent reported having had symptoms consistent with stroke or TIA but only 35% went to a hospital. The vast majority of the respondents said they were awaiting for the end of the quarantine to resume their usual medical care.ConclusionsThe implementation of a quarantine may have some serious adverse effects on the prevention, diagnosis and treatment of stroke. These undesirable aspects should be taken into consideration in the planning, communication and implementation of health policies.

The biosorption of Co(II) on three fungal biomasses: Paecilomyces sp., Penicillium sp., and Aspergillus niger, was studied in this work. The fungal biomass of Paecilomyces sp. showed the best results, since it removes 93% at 24 h of incubation, while the biomasses of Penicillium sp. and Aspergillus niger are less efficient, since they remove the metal 77.5% and 70%, respectively, in the same time of incubation, with an optimum pH of removal for the three analyzed biomasses of 5.0 ± 0.2 at 28°C. Regarding the temperature of incubation, the most efficient biomass was that of Paecilomyces sp., since it removes 100%, at 50°C, while the biomasses of Penicillium sp. and Aspergillus niger remove 97.1% and 94.1%, at the same temperature, in 24 hours of incubation. On the contrary, if the concentration of the metal is increased, the removal capacity for the three analyzed biomasses decreases; if the concentration of the bioadsorbent is increased, the removal of the metal also increases. It was observed that, after 4 and 7 days of incubation, 100%, 100%, and 96.4% of Co(II) present in naturally contaminated water were removed, respectively.

The objective of this work was to study the resistance and removal capacity of heavy metals by the fungus Aspergillus niger. We analyzed the resistance to some heavy metals by dry weight and plate: the fungus grew in 2000 ppm of zinc, lead, and mercury, 1200 and 1000 ppm of arsenic (III) and (VI), 800 ppm of fluor and cobalt, and least in cadmium (400 ppm). With respect to their potential of removal of heavy metals, this removal was achieved for zinc (100%), mercury (83.2%), fluor (83%), cobalt (71.4%), fairly silver (48%), and copper (37%). The ideal conditions for the removal of 100 mg/L of the heavy metals were 28°C, pH between 4.0 and 5.5, 100 ppm of heavy metal, and 1 g of fungal biomass.