Here, we present a facile and low-cost method to produce hierarchically porous graphene-based carbons from a biomass source. Three-dimensional (3D) graphene-based carbons were produced through continuous sequential steps such as the formation and transformation of glucose-based polymers into 3D foam-like structures and their subsequent carbonization to form the corresponding macroporous carbons with thin graphene-based carbon walls of macropores and intersectional carbon skeletons. Physical and chemical activation was then performed on this carbon to create micro- and meso-pores, thereby producing hierarchically porous biomass-derived graphene-based carbons with a high Brunauer-Emmett-Teller specific surface area of 3,657 m2 g−1. Owing to its exceptionally high surface area, interconnected hierarchical pore networks, and a high degree of graphitization, this carbon exhibited a high specific capacitance of 175 F g−1 in ionic liquid electrolyte. A supercapacitor constructed with this carbon yielded a maximum energy density of 74 Wh kg−1 and a maximum power density of 408 kW kg−1, based on the total mass of electrodes, which is comparable to those of the state-of-the-art graphene-based carbons. This approach holds promise for the low-cost and readily scalable production of high performance electrode materials for supercapacitors.

To resist the energy crisis and increasingly environmental pollution, there is a great demand for the development of sustainable materials for use in high-performance energy storage devices and environmental applications. However, it is a great challenge to realize both ultrahigh power density and high energy density in symmetric supercapacitors (SCs) by using materials synthesized from bioresources. Herein, we report the synthesis of hierarchical and lightweight graphene aerogels (GAs) with interconnected three-dimensional (3D) nanostructures for the fabrication of high performance coin cell-type SCs. GAs synthesized from pear exhibited high surface area (1001 m 2 g −1 ) and pore volume (0.68 cm 3 g −1 ), which tremendously increase its surface area up to 2323 m 2 g −1 and pore volume of 1.15 cm 3 g −1 after chemical activation. SCs based on activated GAs delivered both high energy density of 56.80 Wh kg −1 and high power density of 620.26 kW kg −1 . The capacitance retention was ∼83% after 10 000 successive cycles of charge/discharge, indicating good cyclability. Moreover, GAs showed great potential as excellent adsorbents for the removal of diverse dyes from wastewater. This approach allows us to take the full advantage of raw materials from nature for promising applications in sustainable energy as high-performance SCs and practical environmental remediation.

BackgroundThe strength of each heart beat and the stiffness of large arteries contribute to blood pressure (BP). When the large arteries are stiff and their resistance greater, the afterload increases and this may change the function of the heart. However, the relation between common carotid artery stiffness and heart function in hypertensive patients has not been clarified.MethodsTwo hundred and twenty hypertensive patients underwent transthoracic and carotid echocardiography. Measurements of local arterial stiffness were taken at the right common carotid artery level and stiffness parameter (β), pressure-strain elasticity modulus and intima-media thickness were calculated. Brachial cuff BP was measured just before starting the carotid study. The patients with any cardiovascular disease, diabetes mellitus, stroke, transient ischemic attack, or carotid stenosis were excluded.ResultsCarotid artery stiffness parameter (β) was correlated with age and left ventricular mass index (p < 0.005). Even though β was not correlated with LV systolic function, it was inversely correlated with diastolic function as measured by early mitral annular velocity. When the artery was stiffer, early mitral annular velocity (e') decreased (p < 0.001) and the index of left atrial (LA) pressure (early diastolic mitral inflow E velocity/e') increased (p = 0.001). In logistic regression, diastolic dysfunction was affected by age (beta -0.385, p = 0.001), LA volume index (beta 0.175, p = 0.013) and β (beta -0.273, p = 0.019).ConclusionIn hypertensive patients, changes in carotid artery stiffness can affect the diastolic function, independent of age and LA volume index. Therefore, measurements and control of carotid stiffness can play an important role in the prevention of diastolic heart failure.

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