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Abstract: The synthesis of graphene in both high quality and quantity via economic ways is highly desirable and meaningful for practical applications. Here we report a simple, green and cost- effective multiple electrochemical exfoliation approach to high quality and high yield (nearly 50%) graphene flakes by using graphite rod from spent zinc–carbon as graphene source. The graphite rod (anode) and platinum (cathode) were placed vertically at bottom and top of the electrochemical cell, with protonic acid (i.e, H2SO4, H3PO4 or H2C2O4) aqueous solution as electrolyte. The vertical cell configuration enables multiple exfoliation process to improve both the quality and yield of graphene sheets from electrochemical exfoliation of graphite. After nitrogen doping, the exfoliated graphene flakes processes excellent electrocatalytic activity, stability and toxicity tolerance for oxygen reduction reaction in alkaline solution. [Copyright &y& Elsevier]

[Display omitted] • N-succinylated chitosan (NCS), mangiferin (MGF) are conjugated into a nanohybrid. • The NCS-MGF conjugate particle size is measured as 100 ∼ 200 nm. • FT-IR and COSY analyses revealed hydrogen-hydrogen coupling between NCS and MGF. • The blood glucose lowered > 67% on 28 days treatment with NCS-MGF. • The NCS-MGF lowered plasma cholesterol > 37% and serum triglycerides > 61%. Mangiferin (MGF), from Mangifera indica is well reported for its hypoglycemic activity and hypolipidemic activity. However, MGF suffers therapeutic limitation due to poor solubility causing disparaging bioavailability. Herein to address this problem, we have incorporated MGF in alginate grafted N-succinylated chitosan (NSC) nanomatrix. Characterization by molecular docking, FT-IR and 2D-NMR (COSY) has revealed that MGF could reinforce interaction with NSC. The OH and CH 2 OH groups of MGF may set interactions with pyranosic OH, CH 2 OH, NH 2 (or NH-succinyl and COOH-succinyl) of NSC. The NSC-MGF nanoconjugate revealed a spherical particle geometry of 100 ∼ 200 nm size. The encapsulated MGF showed 100% release in vitro. In vivo, NSC-MGF nanoconjugate revealed blood glucose lowering from 300 mg/dL to ∼ 90 mg/dL as well as ∼ 37% lowering of total plasma cholesterol. This is well comparative to the earlier reports which acknowledged only 1 ∼ 36% lowering of plasma cholesterol with MGF. Furthermore, NSC-MGF lowered serum trigyceride to ∼ 61%, while in earlier studies, only 10 ∼ 40% serum triglycerides reduction was found with solitary MGF. [ABSTRACT FROM AUTHOR]