Use of Stainless-Steel Electrodes on the Electrochemical Oxidation of Naproxen and its Transformation Products in Surface Water

In this study, stainless-steel electrodes were used to effectively oxidize naproxen and its transformation products in surface water by electrochemical oxidation in short reaction times. An evaluation of the effects of current density, chloride concentrations, and pH on the electrochemical oxidation process (mechanisms, kinetics, and reaction times) was conducted. Results showed that degradation rates of naproxen were greater, and the reaction times were shorter than those reported in other studies for other compounds and electrode materials. Oxidation naproxen and its transformation products were faster at high current densities, high chloride concentrations, and low pH conditions; however, good performance of the electrochemical oxidation process was observed at 16.3 mA/cm2 and pH 5 for both the naproxen and its transformation products, which were oxidized in only 15 min for the treated effluent and 30 min in the case of sludge. At pH 3 and 5, the number of transformation products and the reaction times required for achieving complete oxidation were greater in sludge than in the treated effluent; meanwhile, at pH 7 and 9, the number of transformation products and reaction times needed for non-detection were of the same order in both the treated effluent and the sludge.

Comparative study on Biochar salt absorption capacity in different saline concentrated solutions

Salt-affected soils are caused by excess accumulation of salts. As soil salinity increases, salt effects can result in the degradation of soils. Previous studies have determined that biochar has the potential to reduce salt stress in soils. In this study, the electroconductive properties of biochar to adsorb salts were investigated in different saline-concentrated solutions. Pelletized, fragmented and powdered biochar were placed in solutions with concentrations of 0, 50, 500, 1000, and 2000 parts per million sodium chloride, respectively. Control treatments consisted of deionized water mixed with salt and no biochar addition. A week after setting the experiment, the electroconductivity measurements were significantly higher relative to the first day. Significant differences were observed among treatments for pelletized, fragmented, and powdered biochar treatments. Increases in electroconductivity values are attributed to ambient temperature changes and differences in particle size. However, pelletized biochar declined in electroconductive values, which is attributed to ions being retained inside the pores of bigger particles. Our study concludes that biochar can adsorb salts at lower sodium chloride concentrations; therefore, it may help mitigate soil salt stress.

Risk factors for recurrent positive results of the nucleic acid amplification test for COVID-19 patients: a retrospective study

Positive retests of COVID-19 represent a public health concern because of the increased risk of transmission. This study explored whether factors other than the nucleic acid amplification test (NAAT) contribute to positive retest results. Patients with COVID-19 admitted to the Guanggu district of the Hubei Maternal and Child Health Hospital between February 17 and March 28, 2020, were retrospectively included. The patients were grouped into the negative (n = 133) and positive (n = 51) retest groups. The results showed that the proportion of patients presenting with cough was higher (P < 0.001) and the proportion of patients with dyspnea was lower (P = 0.018) in the positive than in the negative retest group. The positive retest group showed shorter durations between symptom onset and hospitalization (P < 0.001) and symptom onset and the first positive NAAT (P = 0.033). The positive retest group had higher basophil counts (P = 0.023) and direct bilirubin (P = 0.032) and chlorine concentrations (P = 0.023) but lower potassium concentrations (P = 0.001) than the negative retest group. Multivariable regression analysis showed that coughing (OR = 7.59, 95% CI 2.28–25.32, P = 0.001) and serum chloride concentrations (OR = 1.38, 95% CI 1.08–1.77, P = 0.010) were independently associated with a positive retest result. Coughing and serum chloride concentrations were independent risk factors for positive NAAT retest results. Patients with a hospital stay of < 2 weeks or a short incubation period should stay in isolation and be monitored to reduce transmission. These results could help identify patients who require closer surveillance.

Correction: Torres et al. Leaching Chalcopyrite with High MnO2 and Chloride Concentrations. Metals 2020, 10, 107

The authors wish to make the following corrections to this paper [...]

Hyper- and Hypo-Osmoregulatory Performance of Atlantic Salmon (Salmo salar) Smolts Infected With Pomphorhynchus tereticollis (Acanthocephala)

Migratory species must cope with different parasite communities in different environments, but little is known about the ecophysiological effects of parasites on migratory performance. Some species/strains of acanthocephalan parasites in the genus Pomphorhynchus use anadromous salmonids as preferred definitive hosts, perforating the intestines, destroying mucosa and inducing inflammation–all of which might affect osmoregulatory function during transition between freshwater and marine environments. We used genetic barcoding to identify acanthocephalans in the intestines of wild Irish Atlantic salmon (Salmo salar L.) smolts as being the recently taxonomically resurrected species Pomphorhynchus tereticollis. We then investigated whether natural infection intensities of this parasite were associated with reduced osmoregulatory performance, as measured by plasma chloride concentrations, or potentially elevated stress, as measured by blood glucose, of hosts in freshwater or saltwater environments (24 or 72 h in ∼26PPT salt water, reflecting salinities of coastal waters through which smolts migrate). Although infection prevalence was high amongst sampled smolts, no associations were found within or across treatment groups between parasite abundance and plasma chloride concentrations or blood glucose levels. We found no intestinal perforations that would indicate P. tereticollis had recently vacated the intestines of smolts in either of the saltwater groups. Exploratory sampling in the 2 years preceding the experiment indicated that parasite prevalence and abundance are consistently high and comparable to the experimental individuals. Collectively, these results indicate that naturally occurring abundances of P. tereticollis do not reduce osmoregulatory function or affect blood glucose content in fresh water or within 72 h of entering coastal waters, although delayed pathologies affecting marine survival may occur. Future consideration of ecophysiological interactions between anadromous fish hosts and their parasites across different osmotic environments should provide general insights into coevolution between migratory hosts and their parasites.

Drying of residual tilapia skin from filleting using a thermophotovoltaic solar dehydrator

Tilapia comprises one of the most cultivated fish species worldwide, mainly commercialized in the form of fillets. As a result, the amount of waste generated by processing is high, with tilapia skin being commonly discarded and not used as food for human consumption. In this context, the aim of this study was to dry residual filleted tilapia skins in a solar dehydrator and perform physical-chemical analyses after drying in order to evaluate the potential for the development of byproducts. The skins were collected at a fish market on Mercado do Peixe in Teresina - PI. Treatments consisted of four sodium chloride concentrations (0.0%; 25.0%; 50.0% and 100.0%), with five replications, totaling 25 samples. The skins were dried in the solar dehydrator for 24 hours, followed by moisture, ash, protein, lipids, pH and water activity analyses. Moisture in the in naturaskins was 57.7%, differing significantly from the dehydrated tilapia skins, which ranged from 9.4% to 10.6%. The ash in the in natura skins was 0.17%, while dehydrated tilapia skins displayed variations from 1.19% to 4.17%. The crude protein found of the in natura skins was 41.4%, significantly different (P <0.05) from the skins submitted to the solar dehydration method. Based on these findings, the use of solar dehydrator for short periods is confirmed to favor the uniform dehydration of residual tilapia skin from filleting, generating a product with satisfactory bromatological patterns for the development of fish-based by-products.

Effects of Variations in Sodium Chloride Concentrations on the Biodegradation of Heptane by Alcaligenes species

Conventional mineral salts medium (MSM) had been used for many years. A modification of the concentration of sodium chloride was attempted in this work to observe the effect or otherwise on microbial activities in reaction tubes. This study was undertaken to assess the biodegradation potentials of Alcaligenes species on heptane. Results showed the hydrocarbon degrading ability of Alcaligenes sp. under varying concentrations of sodium chloride salt for a period of sixteen (16) days at two to four days interval. Due to its rapid rate of multiplication, a steady increase in bacterial growth was observed during the experiment. Alcaligenes sp. showed appreciable growth on heptane with a reading of 6.5x108cfu/ml on Day 16. Also, the regeneration rate of Alcaligenes sp. was found to be rapid on heptane in the presence of 4M concentration of NaCl with a reading of 1.18x109cfu/ ml on Day 16. This study shows that increased sodium chloride concentration aids the utilization of heptane by Alcaligenes sp. Hence, Alcaligenes sp. is a promising isolate that can be used for the bioremediation of hydrocarbon contaminated sites in saline environment.