Yerba mate: From waste to activated carbon for supercapacitors.

Developing technological solutions that use yerba mate waste as precursors is key to reducing the environmental impact caused by the lack of treatment and its accumulation in landfills. Due to their physicochemical properties, these residues can be used to develop activated carbons. Activated carbon is a versatile material with a high surface area that can be used for energy storage. In this work, yerba mate residues were valued by producing chemically activated carbon to be used as electrode material in supercapacitors. Activated carbons were developed through chemical activation in two steps with KOH. Variables such as impregnation ratio and activation temperature are studied. The developed carbons were characterized by physicochemical and electrochemical techniques. They were found to have high surface areas, up to 1800 m2 g-1, with a hierarchical porous distribution. A maximum specific capacitance of 644 F g-1 at 0.1 A g-1, and power values of ca 32,000 W kg-1, at 33 A g-1 were found. All the synthesized carbons have excellent electrochemical properties and are suitable for use as active material in supercapacitors.

Effectiveness of Two Targeted Temperature Management Methods After Pediatric Postcardiac Arrest: A Multicenter International Study.

OBJECTIVES: It is currently recommended that after return of spontaneous circulation following cardiac arrest, fever should be prevented using TTM through a servo-controlled system. This technology is not yet available in many global settings, where manual physical measures without servo-control is the only option. Our aim was to compare feasibility, safety and quality assurance of servo-controlled system versus no servo-controlled system cooling, TTM protocols for cooling, maintenance and rewarming following return of spontaneous circulation after cardiac arrest in children. DESIGN: Prospective, multicenter, nonrandomized, study. SETTING: PICUs of 20 hospitals in South America, Spain, and Italy, 2012-2014. PATIENTS: Under 18 years old with a cardiac arrest longer than 2 minutes, in coma and surviving to PICU admission requiring mechanical ventilation were included. METHODS: TTM to 32-34°C was performed by prospectively designed protocol across 20 centers, with either servo-controlled system or no servo-controlled system methods, depending on servo-controlled system availability. We analyzed clinical data, cardiac arrest, temperature, mechanical ventilation duration, length of hospitalization, complications, survival, and neurologic outcomes at 6 months. PRIMARY OUTCOME: feasibility, safety and quality assurance of the cooling technique and secondary outcome: survival and Pediatric Cerebral Performance Category at 6 months. MEASUREMENTS AND MAIN RESULTS: Seventy patients were recruited, 51 of 70 TTM (72.8%) with servo-controlled system. TTM induction, maintenance, and rewarming were feasible in both groups. Servo-controlled system was more effective than no servo-controlled system in maintaining TTM (69 vs 60%; p = 0.004). Servo-controlled system had fewer temperatures above 38.1°C during the 5 days of TTM (0.1% vs 2.9%; p < 0.001). No differences in mortality, complications, length of mechanical ventilation and of stay, or neurologic sequelae were found between the two groups. CONCLUSIONS: TTM protocol (for cooling, maintenance and rewarming) following return of spontaneous circulation after cardiac arrest in children was feasible and safe with both servo-controlled system and no servo-controlled system techniques. Achieving, maintaining, and rewarming within protocol targets were more effective with servo-controlled system versus no servo-controlled system techniques.