Anthracene modified graphene for C60/C70 fullerenes capture and construction of energy storage materials

Graphene functionalized with dianthracene malonate was synthesized and used subsequently for construction of covalently bound graphene-fullerene hybrid nanomaterials. For this purpose, novel approach of Diels–Alder reaction of C60/C70 fullerene cores with anthracene moieties previously introduced onto graphene surface was successfully employed. Structure and composition of obtained graphene and its derivatives were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. Obtained results revealed that both C60 and C70 fullerenes were found to be capable of formation desired Diels–Alder adducts, yielding products of different morphology. Capacitive properties of the synthesized energy storage nanomaterials were determined by means of cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements, revealing that functionalization of graphene with C60 moieties enhances its energy storage properties.

Nitrogen-Doped Carbon Boosting Fe2O3 Anode Performance for Long-Life Supercapacitors

Here, we report Fe2O3/N-doped carbon (Fe2O3/CN) composites via one-step facile calcination process by using FeOOH and PANI as precursor. The results show that N-doped carbon is helpful to enhance the electrochemical properties of Fe2O3. N-doped carbon not only enhances the conductivity of Fe2O3 electrode, but also alleviates the volume expansion of Fe2O3 in the process of repeated charge and discharge. In addition, the synergistic effect of Fe2O3 and N-doped porous carbon makes the composites show higher capacitive properties (538.7 mF/cm2 at 5 mA/cm2) and cycle life (100% retention after 2000 cycles). In addition, its superior electrochemical performance is also proved in symmetrical supercapacitor. After 4900 cycles with current density of 10 mA/cm2, its capacity retention rate is 100%. So Fe2O3/N-doped carbon as electrode materials for long-life symmetrical supercapacitors has broad application prospects.

Digital core modeling technology for determining the reservoir-capacitive properties of terrigenous reservoirs

For today digital core modelling technology is demanded and developing instrument in conducting the main reservoir-capacitive properties of terrigenous rocks. This technology is becoming more widespread in connection with the development of computer and nanotechnologies. The main attempts to apply the digital core model in practice have been undertaken in the last decade, although the first examples of its use for the analysis of reservoir rocks date back to the 80s of the last century. Improvement of digital core modeling technology will allow to cope with the problem of lack or absence of core material, as well as to solve the problems of studying loose, weakly cemented and other rocks, "problematic" of conducting physical experiments. In addition, it seems relevant to create a digital core block that fits into the general digitalization platform of technologies related to reservoir-capacitive properties in the development of hydrocarbon fields. With the use of a digital core model, it also becomes possible to effectively refine and supplement the calculated parameters in laboratory core studies, reducing the likelihood of errors in the obtained results.

Fractional-order Approach to Modeling and Characterizing the Complex and Frequency-dependent Apparent Arterial Compliance: In Human and Animal Validation

Recently, experimental and theoretical studies have revealed the potential of fractional calculus to represent viscoelastic blood vessel and arterial biomechanical properties. This paper presents five fractional-order models to describe the dynamic relationship between aortic blood pressure and volume, representing the apparent vascular compliance. The proposed model employs fractional-order capacitor element (FOC) to lump the complex and frequency dependence characteristics of arterial compliance. FOC combines both resistive and capacitive properties, which the fractional differentiation order, alpha, can control. The proposed representations have been compared with generalized integer-order models of arterial compliance. All structures have been validated using different aortic pressure and flow rate waveforms collected from various human and animal species such as pigs and dogs. The results demonstrate that the fractional-order scheme can reconstruct the overall dynamic of the complex and frequency-dependent apparent compliance dynamic and reduce the complexity. The physiological relevance of the proposed models' parameters was assessed by evaluating the variance-based global sensitivity analysis. Moreover, the simplest fractional-order representation has been embed in a global arterial lumped parameter representation to develop a novel fractional-order modified arterial Windkessel. The introduced arterial model has been validated by applying real human and animal hemodynamic data and shows an accurate reconstruction of the proximal blood pressure. The novel proposed paradigm confers a potential to be adopted in clinical practice and basic cardiovascular mechanics research.

Graphene/Fe3O4 Nanocomposite as a Promising Material for Chemical Current Sources: A Theoretical Study

The outstanding mechanical and conductive properties of graphene and high theoretical capacity of magnetite make a composite based on these two structures a prospective material for application in flexible energy storage devices. In this study using quantum chemical methods, the influence of magnetite concentration on energetic and electronic parameters of graphene/Fe3O4 composites is estimated. It is found that the addition of magnetite to pure graphene significantly changes its zone structure and capacitive properties. By varying the concentration of Fe3O4 particles, it is possible to tune the capacity of the composite for application in hybrid and symmetric supercapacitors.

Biomass-Derived Carbons as Versatile Materials for Energy-Related Applications: Capacitive Properties vs. Oxygen Reduction Reaction Catalysis

Biomass-derived carbons are very attractive materials due to the possibility of tuning their properties for different energy-related applications. Various pore sizes, conductivities and the inherent presence of heteroatoms make them attractive for different electrochemical reactions, including the implementation of electrochemical capacitors or fuel cell electrodes. This contribution demonstrates how different biomass-derived carbons prepared from the same precursor of viscose fibers can reach appreciable capacitances (up to 200 F g−1) or a high selectivity for the oxygen reduction reaction (ORR). We find that a highly specific surface area and a large mesopore volume dominate the capacitive response in both aqueous and non-aqueous electrolytic solutions. While the oxygen reduction reaction activity is not dominated by the same factors at low ORR overpotentials, these take the dominant role over surface chemistry at high ORR overpotentials. Due to the high selectivity of the O2 reduction to peroxide and the appreciable specific capacitances, it is suggested that activated carbon fibers derived from viscose fibers are an attractive and versatile material for electrochemical energy conversion applications.