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Fiber supercapacitors have attracted public attentions because of their merits of relatively high capacitance density, flexibility and easy integration with various electronic devices. In this work, a flexible coaxial-type fiber solid-state asymmetrical supercapacitor (ASC) based on Ni3S2 nanorod array electrode and pen ink electrode was successfully fabricated. The Ni3S2 nanorod array electrode was synthesized by directly growing Ni3S2 nanorod arrays on a nickel wire through a facile hydrothermal method and the pen ink electrode as negative electrode was synthesized by a simple dip-coating method. The solid-state ASC device presents a stable voltage window of 1.4 V and behaves a high specific capacitance of 34.9 F g−1 (87.25 F cm−1) at a scan rate of 10 mV s−1. Compared with the symmetric supercapacitor (SSC) based on Ni3S2 electrodes, the ASC device provide an increased energy density of 8.2 Wh kg−1 (0.81 mWh cm−3) at the power density of 214.6 W kg−1 (21.12 mW cm−3). In addition, the ASC device also exhibits excellent electrochemical stability with 93.1% of initial specific capacitance after 3000 consecutive cycles and good mechanical stability. These encouraging results present its great potential in flexible solid-state energy storage devices.
Macroporous manganese oxide films were produced via template-assisted electrodeposition methodology employing polystyrene spheres with different diameters as template, thereby producing films with different pore sizes. The obtained films were true casts of the template(s) employed, as evidenced by Field Emission Scanning Electron Microscopy. The influence of pore size on capacitive behavior was assessed by cyclic voltammetry experiments in conventional propylene carbonate/LiClO4. Besides the influence of pore size, four different ionic liquids (ILs) were studied as electrolytes, showing that the physico–chemical nature of IL strongly affects the capacitive behavior of macroporous manganese oxide films, particularly in terms of stability throughout successive charge/discharge cycles. Optimal performance was obtained using 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide ([BMMI][Tf2N]), in which a constant increase in capacitance was observed for the first 700 charge/discharge cycles. This capacitance remained constant, at least until the 1,000 cycle, and was higher than the capacitance achieved using conventional organic solvents. Moreover, the electrochemical window obtained using [BMMI][Tf2N] was widened (from 0.9 V to 1.5 V), corresponding to a significant gain (up to 75%) in terms of energy density. Thus, the development of electrochemical capacitors may significantly benefit from macroporous manganese oxide film electrochemistry employing ionic liquids as electrolytes.
This manuscript presents the formulation and implementation of a particle-resolved 3D finite element (3DFE) model to study the effect of cathode microstructure on the electrochemical and mechanical responses of lithium-ion batteries (LIBs) during the discharge process. In this model, active particles (lithium iron phosphate) are explicitly resolved to allow the direct assignment of boundary conditions on particle surfaces. To incorporate the effect of binder phase in a numerically efficient manner, it is modeled as a homogenized matrix with a pore-filling electrolyte that allows the transport of both electrons and ions. A new virtual packing algorithm is implemented to reconstruct three cathode microstructures, one of which has an idealized microstructure with spherical particles of similar radii. This microstructural model is used for the verification of the 3DFE model through comparison with the pseudo two-dimensional (P2D) model. The other two cathodes, which are composed of two-size spherical and arbitrary-shaped particles, are used to study the impact of microstructure and discharge rate on the electro-chemo-mechanical behavior. The proposed model predicts the effect of electrode microstructure on active material utilization, as well as the magnitude and distribution of mechanical stresses developed in particles. We also study how the mechanical response of the cathode is affected by the binder stiffness.
A pharmacological screen has identified the histone methyltransferase G9a as a target to reactivate imprinted genes in a mouse model of Prader–Willi Syndrome that improves growth and survival.
The dramatic loss of glacial mass in low latitudes is causing shifts in downstream water availability and use during the driest months of the year. The world’s largest concentration of tropical glaciers lies in the Cordillera Blanca range of Peru, where glacial runoff is declining and regional stresses are emerging over water resources. Throughout the Cordillera Blanca, groundwater inputs from alpine meadow–talus complexes, locally known as pampas, supply proglacial streams with up to 80% of their flow during the region’s dry season. Structural knowledge of the pampa aquifers is needed to estimate their drainable groundwater storage capacity and residence time, to elucidate the role and importance of alpine groundwater storage in the regional water budget of the Cordillera Blanca. To understand the structure of these proglacial aquifers, multiple near-surface geophysical methods were implemented in a proglacial valley near dense networks of spring-fed tributaries. Geophysical results and borehole logs suggest groundwater is stored in a confined aquifer composed of buried talus deposits overlain by lacustrine clay, while deeper portions of the unit, 10–15 m in depth, are relatively clay-free and more hydraulically conductive. Based on these findings and assumptions of aquifer porosity, the pampas of the Callejon de Huaylas may store from 0.006 to 0.02 km3 of groundwater. Furthermore, these findings suggest that the talus aquifers of the Cordillera Blanca were formed in proglacial lakes, followed by infilling with fine lacustrine sediments that confine lower units and allow for groundwater discharge to springs via macropores and preferential flow.
This paper assesses the energy and water consumption practices of existing housing in Saudi Arabia, with the ultimate aim of establishing guidelines for delivering sustainable residential buildings in the near future. In order to achieve this aim the current status of a typical Saudi residence (i.e. an apartment complex) is investigated in terms of energy and water consumption using simulation software packages. The paper then examines the prospects for applying various measures to the typical Saudi residence to manage energy and water use more sustainably. This research identifies several design-related faults common to Saudi Arabian house design. These faults contribute to an inefficient use of energy and domestic water resources. Finally, the paper puts forward a set of recommendations and guidelines, design-related and otherwise, to enhance the sustainability of future Saudi residential buildings.
Polymer electrolyte membrane fuel cells (PEMFCs) show great promise in portable, automotive, and stationary applications. They have reached the test and demonstration phase in automotive and power markets today. This paper is focused on a stand-alone residential PEMFC power system that provides the electricity needs of the house. A novel stochastic sizing methodology is developed that considers both fuel cell system dynamics and residential load dynamics in overall system sizing for the stand-alone residential fuel cell power system. Understanding the nature of demand side is critical in stand-alone system sizing. Thus, experimental measurements have been completed to capture the load side dynamics in detail. No such data is found in the current literature. The Threshold Bootstrap method is used to model the residential load demand and to produce many realistic load profiles. Matlab/Simulink is used to run system simulations to determine system sizes based on parameters defined through a designed experiment. Comparison between the proposed sizing method and a possible worst case scenario sizing is given. The new sizing methodology can be used together with sophisticated demand analysis programs to obtain customized sizing for each user as stand-alone power systems become more viable.
The spectroelectrochemical behavior of a copper electrode in 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4) ionic liquid containing benzotriazole (BTAH) has been investigated by cyclic voltammetry and surface-enhanced Raman scattering (SERS). The cyclic voltammograms have shown that in the presence of BTAH there is a considerable decrease in the anodic currents, suggesting that BTAH inhibits the oxidation of copper in BMI.BF4. The SERS results have shown that at potentials positive to the potential of zero charge (PZC) for copper in BMI.BF4, BTAH interacts with the copper(I) on the metal surface leading to the formation of the [Cu(I)BTA] n polymeric film that is responsible for the corrosion inhibition process. At potentials negative to the PZC BTAH adsorbs chemically on the copper surface. This adsorption is characterized by the observation of the ν(Cu-N) stretching mode at 253cm−1 and by the δ(NH) bending mode near 1115cm−1.
Monoclinic structure Li3V2(PO4)3/C composite powders are synthesized via a novel homogeneous mixing route followed by a one-step heat treatment. The composites were characterized by X-ray diffraction (XRD) and galvanostatic charge/discharge, CV measurements. The influence of the heat treatment on the electrochemical properties of Li3V2(PO4)3/C composites was investigated. To examine the effect of residual carbon content on the properties of the composites, six samples with 1.2, 2.3, 3.4, 4.4, 5.8, and 7.0 wt% carbon were prepared. The sample with 4.4 wt% carbon exhibited good cycling performance and rate capability in the range of 3.0–4.8 V.
This paper reviews the literature on the preparation aspect of non-noble electrocatalysts for PEM fuel cell reactions, especially focusing on cathode electrocatalyst preparation methods. Various effective synthesis methods for two kinds of promising catalysts such as transition metal chalcogenides, and heat-treated nitrogen containing complexes (macrocyclic complexes) are discussed. Though some remarkable progress has been made in catalyst preparation techniques, neither of these catalysts has reached the level of a Pt based catalyst in terms of catalytic activity, durability and chemical/electrochemical stability. In order to make non-noble electrocatalysts commercially feasible, cost-effective and innovative, catalyst synthesis methods are needed for new catalyst discovery and catalyst performance optimization.
Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by mutations affecting UBE3A gene expression. Previous studies in mice revealed distinct critical periods during neurodevelopment in which reactivation of Ube3a gene expression can prevent the onset of behavioral deficits. Whether UBE3A is required for brain function throughout life is unknown. Here, we address the importance of maintaining UBE3A expression after normal brain development.
Na3V2(PO4)2F3 is considered to be a prospective candidate cathode for sodium ion batteries owing to its high operating voltage and excellent structural stability. However, the cycle performance together with rate capability of Na3V2(PO4)2F3 has been restrained on account of its low electronic conductivity. In this work, a series of carbon-coated Na3V2(PO4)2F3 samples were fabricated by utilizing a facile one-step carbothermal reduction method. The well crystallized Na3V2(PO4)2F3/C showed good capacity performance where it delivered an initial discharge capacity of 112.3 mAh g−1 at 1C rate with a high retention of 89.7% after 100 cycles. Even at the current rate of 8C, it could give a capacity of 64 mAh g−1. The cycle stability of Na3V2(PO4)2F3/C at the high temperature of 55 °C was also demonstrated. Besides, the Na3V2(PO4)2F3/C showed good long-term durability, of which the capacity loss averaged 0.0264% per cycle at 2C rate at room temperature. Furthermore, the electrochemical impedance spectroscopy well explained the difference about the electrochemical performance of different Na3V2(PO4)2F3/C samples. More importantly, Na3V2(PO4)2F3/C is of great competence to serve as cathode for future sodium ion batteries applied in energy storage systems, and this simple one-step carbothermal reduction strategy to get Na3V2(PO4)2F3/C will make contributions to accelerating this process.
For the fabrication of flexible full lithium ion batteries (FLIBs), suitable anode material is highly demanded. Iron nitrides hold great promise as anode material for lithium ion batteries (LIBs) due to their large specific capacity and high electrical conductivity. However, their poor electrochemical stability severely limits their application as electrode material for LIBs. In this article, we synthesize binder-free Fe2N nanoparticles (Fe2N NPs) as high performance free-standing anode for LIBs. When tested in a half-cell, the binder-free Fe2N NPs delivered a high reversible capacity of 900mAh/g. At high current density of 6000mA/g, the binder-free Fe2N NPs exhibits excellent cyclic stability with 76% capacity retention after 300 cycles. We also demonstrated high power and energy density FLIB based on Fe2N NPs anode and LiCoO2 cathode for the first time. The Fe2N//LiCoO2 FLIB device shows attractive electrochemical performance and high flexibility. More importantly, Fe2N//LiCoO2 FLIB device achieved a high power density of 3200W/kg and a high energy density of 688Wh/kg. These values are substantially enhanced compared to most of the reported LIB devices. This work constitutes the first demonstration of using Fe2N NPs as high performance anode, which could potentially improve the performance of energy storage devices.
A membrane electrode assembly (MEA) was fabricated using proton conductive hydrogensulfated fullerenol (C60(OSO3H) n (OH) n ). Rate-controlled mass flow of hydrogen was performed by applying voltage to both electrodes of the MEA without humidification. The amount of the electrochemically transported hydrogen through the MEA increased as the applied current increased, obeying Faraday's law. Residual gas analysis of the transported hydrogen showed that the transported hydrogen contains trace amounts of water less than 1%.
Acetylcholinesterase (AChE) is an important enzyme in the pathogenesis of Alzheimer’s disease (AD). Comparative quantitative structure-activity relationship (QSAR) analyses on some huprines inhibitors against AChE were carried out using comparative molecular field analysis (CoMFA), comparative molecular similarity indices analysis (CoMSIA), and hologram QSAR (HQSAR) methods. Three highly predictive QSAR models were constructed successfully based on the training set. The CoMFA, CoMSIA, and HQSAR models have values of r2 = 0.988, q2 = 0.757, ONC = 6; r2 = 0.966, q2 = 0.645, ONC = 5; and r2 = 0.957, q2 = 0.736, ONC = 6. The predictabilities were validated using an external test sets, and the predictive r2 values obtained by the three models were 0.984, 0.973, and 0.783, respectively. The analysis was performed by combining the CoMFA and CoMSIA field distributions with the active sites of the AChE to further understand the vital interactions between huprines and the protease. On the basis of the QSAR study, 14 new potent molecules have been designed and six of them are predicted to be more active than the best active compound 24 described in the literature. The final QSAR models could be helpful in design and development of novel active AChE inhibitors.
In the past several years, many efforts have been made to develop polyanion-type cathode materials for sodium ion batteries by chemists and material scientists. These materials are one of the main types of promising cathodes though the studies are still in their infancy. This paper reviews almost all the important advances of polyanion-type cathodes on their syntheses, crystal structures, morphologies, electrochemical performance and Na redox mechanisms. It specifically focuses on their crystal chemistry and electrochemical behaviors. The contents are divided into several categories according to their chemical compositions. After introduction of the synthetic methods, phosphates (ortho-, pyro- and fluoro-), silicates, sulfates, and mixed anions type cathodes are summarized and discussed successively.
Molybdenum disulfide nanoflakes (MoS2) are superior material for their semiconducting properties. For bulk and monolayer MoS2 the band gap changes from indirect-to-direct, respectively. So, it exhibits promising prospects in the applications of optoelectronics and valleytronics, such as solar cells, transistors, photodetectors, etc. In this research, the influence of different Ar flow rates as the carrier gas, is investigated for growing MoS2 nanoflakes on silicon substrates using one-step thermal chemical vapor deposition by simultaneously evaporating of solid sources like sulfur and molybdenum trioxide powders. The structural and optical properties of the obtained nanoflakes are assessed by using X-ray diffraction pattern, scanning electron microscopy, UV–visible absorption, photoluminescence and Raman spectroscopy. It is shown that, Ar gas flow rate is strongly affects on the final products as few-layer MoS2 structures. Moreover, the abundance of MoS2 in comparison to MoO2 and MoO3 structures, in the obtained nanoflakes, is influenced by the Ar flow rate.
Objective The objective of this study was the development and evaluation of nonlinear electroencephalography parameters which assess hypoxia-induced EEG alterations, and describe the temporal characteristics of different hypoxic levels’ residual effect upon the brain electrical activity. Methods Multichannel EEG, pO2, pCO2, ECG, and respiration measurements were recorded from 10 subjects exposed to three experimental conditions (100% oxygen, hypoxia, recovery) at three-levels of reduced barometric pressure. The mean spectral power of EEG under each session and altitude were estimated for the standard bands. Approximate Entropy (ApEn) of EEG segments was calculated, and the ApEn’s time-courses were smoothed by a moving average filter. On the smoothed diagrams, parameters were defined. Results A significant increase in total power and power of theta and alpha bands was observed during hypoxia. Visual interpretation of ApEn time-courses revealed a characteristic pattern (decreasing during hypoxia and recovering after oxygen re-administration). The introduced qEEG parameters S 1 and K 1 distinguished successfully the three hypoxic conditions. Conclusions The introduced parameters based on ApEn time-courses are assessing reliably and effectively the different hypoxic levels. ApEn decrease may be explained by neurons’ functional isolation due to hypoxia since decreased complexity corresponds to greater autonomy of components, although this interpretation should be further supported by electrocorticographic animal studies. Significance The introduced qEEG parameters seem to be appropriate for assessing the hypoxia-related neurophysiological state of patients in the hyperbaric chambers in the treatment of decompression sickness, carbon dioxide poisoning, and mountaineering.
A new SiO2/Cu/polyacrylonitrile-C composite (donated as SiO2/Cu/PAN-C) is prepared by mechanical ball milling and heat treatment of CuO-coated SiO2 and polyacrylonitrile. During heat treatment, Cu is produced by reduction of CuO and SiO2 is embedded in the matrix of Cu and PAN-C. SiO2 in the composite presents a specific capacity of 1230 mAh g−1, and exhibits excellent cyclic stability and rate capability when cycling in the voltage range of 0.0–3.0 V. Electrochemical impedance spectra (EIS) indicate that the addition of Cu effectively improves the conductivity of electrode and diminishes interfacial impedance.
A structural and micro-pore analysis of a series of heat treated electrolytic manganese dioxide (EMD) samples has been conducted. In terms of crystal structure, the original EMD with γ-MnO2 structure (orthorhombic unit cell) was found to progressively convert to β-MnO2 (tetragonal unit cell) at elevated temperatures. The structural transition was kinetically limited, with the higher temperatures leading to a greater degree of transformation. The orthorhombic γ-MnO2 unit cell was found to contract along the a and b axes, while along the c axis an expansion was observed only at the highest heat treatment temperatures. These changes occur as a result of manganese ion diffusion leading to the formation of a denser, more defect free material. The porosity of these heat treated EMD samples was also examined by N2 gas adsorption combined with various interpretive techniques such as the Kelvin equation, MP method, Dubinin–Radushkevich method, Dubinin–Astakhov method and a more modern density functional theory based approach. Despite shortcomings associated with certain techniques, all clearly indicated that the EMD micro-pore volume decreased and the meso- and macro-pore volume increased as the heat treatment temperature was increased. This was justified as a result of manganese ion movement during the structural rearrangement causing the small pores to be progressively sintered shut, while the larger pores were formed as a result of stress-induced cracking in the denser final product.
Amorphous silicon is investigated as a negative electrode (anode) material for lithium-ion batteries. A thin (500Å) film of amorphous silicon is cycled versus a lithium electrode. A maximum discharge capacity of 4Ahg−1 is observed by cycling over a voltage window of 0–3V, but capacity fading is rapid after 20 cycles. This capacity fading can be overcome, to more than 400 cycles, by changing the lower voltage limit to 0.2V. In this situation, the discharge capacity is about 400mAhg−1.
Spherical flowerlike NiOand NiO@CeO2(2.5, 5.0 and 7.5 wt%) composites are successfully prepared by a simple hydrothermal method. NiOmaterials show spherical flower morphology with a radius of 4–5 μm, and the CeO2nano-particles deposit on the surface of NiOpetals (nanosheets), and then form porous NiO@CeO2flower-like microspheres. NiOpetals are covered with electrochemical active CeO2nanoparticles, leading to an advantageous synergistic storage effect due to the charge redistribution in the NiO|CeO2interface, which can decrease the polarization and accelerate the ion diffusion. NiO@CeO2(5.0 wt%) electrode shows an excellent specific capacitance of 960.4 F g−1at 20 A g−1and keeps about 95.84% capacitance retention after 10000 cycles. Whereas the NiO, NiO@CeO2(2.5 wt%) and NiO@CeO2(7.5 wt%) electrodes have capacitances of 543.6, 1428 and 1143.6 F g−1corresponding to capacitance retentions of 74.39%, 62.55% and 58.41% after 10000 cycles, respectively. The first-principles calculation exhibits that a strong chemical bond between O and Ce(Ni) can be formed at the interface, and such a chemical bonding between the two components is very helpful for the stabilization of the composite during repeated cycles, responsible for the good cycling performance of the materials. Therefore, the super capacitance and excellent cycling stability of NiO@CeO2(5.0 wt%) electrode at high current density can be ascribed to the unique composition design and architectures.