Cobalt electrowinning is an intensive energy-consuming process, and allied to the increasing demand for pure cobalt, has led to the need for optimization. Based on a statistical approach, the effects of additives, including sodium lauryl sulfate (SLS), boric acid (H3BO3), and cobalt chloride (CoCl2) on the current efficiency of electrowinning have been studied using the cyclic voltammetry (CV). CV tests indicated the concentration range of the more appropriate additives to be used in the factorial design study of electrowinning. Regarding the electrowinning tests, the addition of 0.05 g L-1 SLS, 10 g L-1 H3BO3, 50 g L-1 Na2SO4, and 1 g L-1 CoCl2 led to a current efficiency of 96% and energy consumption of 1.95 kWh kg-1, along with a smooth metallic deposit without evident pits and other defects. SLS in its higher concentration level led to the formation of compact structures, while the higher concentration level of H3BO3, lightens the deposits.

Abstract Objective: Stroke is an important cause of disability and death in adults worldwide. However, it is preventable in most cases and treatable as long as patients recognize it and reach capable medical facilities in time. This community-based study investigated students' stroke knowledge, Emergency Medical Services (EMS) activation, associated risk factors, warning signs and symptoms, and prior experience from different educational levels in the KIDS SAVE LIVES BRAZIL project. Methods: The authors conducted the survey with a structured questionnaire in 2019‒2020. Results: Students from the elementary-school (n = 1187, ~13 y.o., prior experience: 14%, 51% women), high-school (n = 806, ~17 y.o., prior experience: 13%, 47% women) and University (n = 1961, ~22 y.o., prior experience: 9%, 66% women) completed the survey. Among the students, the awareness of stroke general knowledge, associated risk factors, and warning signs and symptoms varied between 42%‒66%. When stimulated, less than 52% of the students associated stroke with hypercholesterolemia, smoking, diabetes, and hypertension. When stimulated, 62%‒65% of students recognized arm weakness, facial drooping, and speech difficulty; only fewer identified acute headache (43%). Interestingly, 67% knew the EMS number; 81% wanted to have stroke education at school, and ~75% wanted it mandatory. Women, higher education, and prior experience were associated with higher scores of knowing risk factors (OR = 1.28, 95% CI: 1.10‒1.48; OR = 2.12, 95% CI: 1.87‒2.40; OR = 1.46, 95% CI: 1.16‒1.83; respectively), and warning signs- symptoms (OR = 2.22, 95% CI: 1.89‒2.60; OR = 3.30, 95% CI: 2.81‒3.87; OR = 2.04, 95% CI: 1.58‒2.63; respectively). Conclusion: Having higher education, prior experience, and being a woman increases stroke-associated risk factors, and warning signs and symptoms identification. Schoolchildren and adolescents should be the main target population for stroke awareness. HIGHLIGHTS Higher education, prior experience, and being women improved the odds of identifying stroke warning signs and symptoms as associated risk factors Improving knowledge, skills, and attitude on acute stroke in the school community may represent a significant advance in public health management Future stroke awareness campaigns and educational efforts should focus on schoolchildren and adolescents, especially in low-income countries

ABSTRACT The present study assessed the competing behavior between metals and extractants applied to the solvent extraction of calcium and/or nickel present in sulfuric solutions using the extractants Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) and/or D2EHPA (di-2-ethylhexyl phosphoric acid). Tests were designed to allow equivalent competing conditions between metals and extractants. Considering metal competition in the aqueous phase, calcium extraction remained unaffected in the presence of nickel, while nickel extraction curves with pH displaced to the right in the presence of calcium when D2EHPA (ΔpH1/2 = 1.4) or Cyanex 272 + D2EHPA (ΔpH1/2 = 0.9) were used. Considering extractant competition in the organic phase, metal extractions with Cyanex 272 + D2EHPA closely followed the curves obtained with D2EHPA, thus evidencing that it acts as the main extractant agent, synergism or antagonism effects being attributed to the presence of Cyanex 272. A synergistic increase in the calcium extraction occurred at pH ≥ 4.5, being unaffected in the presence of nickel, whereas rejection for nickel occurred in the whole pH range in the absence of calcium, and at pH < 5.5 in the presence of calcium. For the operating conditions investigated, Ca/Ni separation reached a maximum at pH = 4.5 (calcium extraction > 80%, nickel extraction < 0.25%, βCa/Ni = 2159).