Sustainable Sulfur-rich Copolymer/Graphene Composite as Lithium-Sulfur Battery Cathode with Excellent Electrochemical Performance

A sulfur-rich copolymer, poly(S-r-C-a) has been synthesized via a sustainable route, showing the utility of two major industrial wastes-elemental sulfur (petroleum waste) and cardanol (agro waste), to explore its potential as cathode material for Li-S batteries. The sulfur-rich copolymer exhibited a reduction in the active material dissolution into the electrolyte and a low self-discharge rate behavior during the rest time compared to an elemental sulfur cathode, indicating the chemical confinement of sulfur units. The presence of organosulfur moieties in copolymer suppress the irreversible deposition of end-discharge products on electrode surfaces and thus improve the electrochemical performances of Li-S batteries. This sulfur copolymer offered a reversible capacity of 892 mA h g(-1) at 2nd cycle and maintained the capacity of 528 mA h g(-1) after 50 cycles at 200 mA g(-1). Reduced graphene oxide (rGO) prepared via a sustainable route was used as a conductive filler to extract the better electrochemical performances from this sulfur copolymer. Such sustainable origin batteries prepared via economically viable showed an improved specific capacity of similar to 975 mA h g(-1) after 100 cycles at 200 mA g(-1) current rate with capacity fading of 0.15% per cycle and maintained a stable performance over 500 cycles at 2000 mA g(-1)

P123 The effect of having volunteers and face masks present at hospital entrances on the wearing of face masks and hand washing

Abstract Background The spread of COVID-19 has put inpatients lives at risk and increased stress on hospital. Simple, cost effective measures such as mask wearing and hand hygiene have been shown to reduce the spread of droplet borne viruses. Compliance with these measures is variable and when performed improperly, reduce efficacy. Objective In this paper we aim to determine whether the provision of masks at hospital entrances and the use of volunteers to ensure correct mask wearing and hand hygiene can improve compliance with infection prevention measures for COVID-19. Method Visitor and staff compliance with mask wearing and hand hygiene measures were observed with and without the presence of masks and volunteers at hospital entrances at a District General Hospital. Results A total of 519 people were observed entering the hospital. Mask wearing went from 71% to 99% (P = &amp;lt;0.001) with the addition of volunteers. Provision of masks increased mask wearing from 56% to 97% (P = &amp;lt;0.001). Hand hygiene was improved from 9% to 84% (P = &amp;lt;0.001) with the presence of volunteers. Discussion A statistically significant improvement in hand hygiene and correct mask wearing was seen with both the presence of volunteers at hospital entrances and with the provision of masks. This is a relatively small study with heterogenous cohorts of staff and visitors. However, these results appear to indicate that use of volunteers and provision of masks at entrances may improve the compliance with the measures that been shown to reduce the in-hospital transmission of COVID-19. </jats:sec

Cardanol benzoxazine-Sulfur Copolymers for Li-S batteries: Symbiosis of Sustainability and Performance

A sulfur-rich copolymer is synthesized via a sustainable, eco-friendly approach using two major wastes namely, elemental sulfur (industrial waste) and cardanol (agro waste) and its application as cathode active material in Li-S battery. The presence of chemically bound sulfur (90 wt%) utilising cardanol (10 wt%) derivative in the copolymer (S90) showed a reduction in the active material dissolution into the electrolyte. In addition, the organic sulfur units get dispersed into the insoluble/insulating Li-2 S-2/Li2S phase and thus found to suppress their irreversible dep-osition. Li-S battery based on S90/multi-walled carbon nano-tubes (MWCNT) (10 wt%) exhibited a reversible capacity of 1302 mAh g(-1) at 2nd cycle, maintaining a high reversible capacity of 928 mAh g(-1) after 70 cycles at a relatively constant coulombic efficiency over 99% at current rate of 200 mA g(-1). At 1000 mA g(-1) current rate, the composite cathode delivered a reversible capacity of 697 mAh g(-1) at 2nd cycle and retained 75% of its initial capacity even after 180 cycles

Photoinduced charge separation in poly(1,4-phenylenevinylene) derivatives studied by electron paramagnetic resonance

We report a study of photoinduced charge separation in poly(1,4-phenylenevinylene) (PPV) derivatives with enhanced exciton dissociation using light-induced electron paramagnetic resonance (EPR). Four polymers were studied; all contained alkoxy and fluorenyl side chain units, and two of them also contained a nitro group on the 7-positon of the fluorenyl moieties. Pulsed EPR detected a light induced polaron for all the polymers with the intensity significantly higher for those with nitro groups. A second center was observed for these materials and spectra could be fitted assuming a radical anion was localized on the nitro groups. The fraction of radical anion and polaron centers was comparable, consistent with intramolecular exciton dissociation for the PPV derivatives containing the nitro groups. © 2008 Elsevier B.V. All rights reserved