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Al and/or Mg-substituted Li[Ni0.8Co0.1Mn0.1−x−y Al x Mg y ]O2 were prepared by a co-precipitation method and characterized by X-ray diffraction with Rietveld refinement, thermogravimetric analysis, differential scanning calorimetry (DSC), and electrochemical measurements. The Rietveld refinement results show that cation mixing of Al and/or Mg-substituted Li[Ni0.8Co0.1Mn0.1−x−y Al x Mg y ]O2 was reduced with increased doping amounts of Al and Mg. The Al and/or Mg substitution in Li[Ni0.8Co0.1Mn0.1]O2 also resulted in improved electrochemical cycling behavior, structural stability, and thermal stability compared to pristine Li[Ni0.8Co0.1Mn0.1]O2. The improvements of electrochemical and thermal properties resulted from the stabilized host structure by Al and/or Mg incorporation into Li[Ni0.8Co0.1Mn0.1]O2.
The layered molybdenum chalcogenide MoS2 has attracted wide attention due to its potential electrochemical applications. Based on its unique physical and chemical properties, numerous advances have shown that nanostructured MoS2, with the advantages of low cost and outstanding properties, is a promising candidate for environmentally benign energy conversion and storage (ECS) devices. Nowadays, in order to lessen the reliance on fossil fuels, the production of hydrogen from water splitting has become an important issue. Hence, developing catalysts composed of earth-abundant elements that possess activities comparable to those of noble metals is of great urgency. According to DFT calculations in terms of HER free-energy diagrams, MoS2 could be used as an effective substitute for noble metals. Meanwhile, MoS2 with various structures has also been applied in the field of energy storage, including batteries and supercapacitors. Additionally, due to their layer-dependent electrical properties, MoS2-based electrochemical devices have been applied as sensors for a variety of chemicals. In this review, we summarize recent advances in the development of MoS2 with high-performance in various electrochemical domains, and recent progress in discovering the mechanisms underlying the enhanced activity. Moreover, we summarize the critical obstacles facing MoS2, and discuss strategies for further improving its activity. Lastly, we offer some suggestions on the pathways toward achieving high performance competitive with noble metal counterparts, and perspectives on practical applications of MoS2 in the future.
In older hospital patients with cognitive spectrum disorders (CSD), mobility should be monitored frequently with standardised and psychometrically sound measurement instruments. This study aimed to examine the responsiveness, minimal important change (MIC), floor effects and ceiling effects of commonly used outcome assessments of mobility capacity in older patients with dementia, delirium or other cognitive impairment.
Porous carbons with controllable and narrow pore-size distributions are prepared from the chemical activation of polyfurfuryl alcohol (PFA). High apparent BET surface areas, up to 2600m2 g−1 (2611m2 g−1 by Density Functional Theory (DFT)), and good electrical conductivities (up to ∼130Scm−1) are obtained. By varying the potassium hydroxide: carbon precursor ratio, the preparation of carbons with different proportions of micro- and fine mesoporosity (<5nm) can be tailored to provide an ideal electronic and ionic pore structure for electrochemical energy-storage devices, such as electrical double-layer capacitors. High specific capacitance values are obtained up to 147Fg−1 in a voltage window of 2.5V using 1M tetraethyl ammonium tetrafluoroborate in acetonitrile. Moreover, excellent high-current and high-frequency performance is demonstrated: 100Fg−1 at 225Ag−1 (10Hz) and ∼30Fg−1 at 100Hz. When comparing the performance with commercial activated carbons (ACs) of similar textural properties, the PFA-derived ACs demonstrated better performance in terms of higher capacitance values and improved rate capabilities. There is a 125% increase in capacitance values at 1kHz.
Different micro–mesoporous carbons derived from d-glucose (GDC), granulated white sugar (WSDC) and highly decomposed Estonian peat (PDC) were synthesized using hydrothermal carbonization and direct activation methods. The resulting carbonaceous materials were activated using chemical (KOH and ZnCl2) and physical (CO2) activation methods. The electrochemical characteristics of the electrical double-layer capacitors (EDLCs) based on 1 M Et3MeNBF4 solution in acetonitrile and EtMeImBF4 were measured using two-electrode cells. The EDLCs assembled had specific capacitances from 20 up to 158 ± 18 F g−1 (in EtMeImBF4) and phase angle values from − 65° to − 88° (at low frequencies). The characteristic time constant values vary more than 10 times. Applying constant power discharge method, very high energy and power densities (34 W h kg−1 at 10 kW kg−1) for activated carbon powders-based EDLCs have been measured. Fitting of impedance data showed that enhanced mesoporosity reduces the adsorption and mass-transfer resistance values.
Interest in the advancement of energy storage methods have risen as energy production trends toward renewable energy sources. Vanadium redox flow batteries (VRFB) are one of the emerging energy storage techniques being developed with the purpose of effectively storing renewable energy. There are currently a limited number of papers published addressing the design considerations of the VRFB, the limitations of each component and what has been/is being done to address said limitations. This review briefly discusses the current need and state of renewable energy production, the fundamental principles behind the VRFB, how it works and the technology restraints. The working principles of each component are highlighted and what design aspects/cues are to be considered when building a VRFB. The limiting determinants of some components are investigated along with the past/current research to address these limitations. Finally, critical research areas are highlighted along with future development recommendations.
A composite polymer electrolyte based on an ionic liquid, Li salt and polymeric ionic liquid that included PIL-functionalized mesoporous silica nanoplates is prepared through a simple solution-casting method. A PIL-functionalized mesoporous silica content (8wt.%) optimized composite polymer electrolyte possesses high ionic conductivity, a high Li ion transference number, and good interfacial stability characteristics superior to those of a plain PIL-based electrolyte or incorporating PIL-functionalized silica nanoplates. The incorporation of porous structured silica nanoplates leads to the creation of a continuous and interconnected conductive network, and weakens the anionic and cationic interactions of the IL and Li salts, thereby improving ionic mobility and charge carrier concentration. Also, the PIL-functionalized mesoporous silica nanoplates effectively improves the electrochemical stability and interfacial stability of the polymer electrolyte with the Li metal electrode and anode electrode, due to its large surface area and the high affinity resulting from porous structures and grafted PIL. Accordingly, Li/LiFePO4 cells with composite polymer electrolyte and PIL-functionalized mesoporous silica nanoplates exhibit remarkably improved discharged capacities and cyclabilities, compared to cells with plain PIL-based polymer electrolyte,displaying a higher average specific capacities at 40 and 60°C, approximating to 228% and 152% enhancements after 100 cycles, respectively.
The behavior of graphite electrodes comprising either synthetic flakes or round-shaped particles, meso carbon microbeads (MCMB) and meso carbon fibers (MCF), were studied at elevated temperatures (up to 80°C) in standard solutions of ethylene carbonate–ethylmethylcarbonate (EC–EMC)/LiPF6. Electron microscopy, X-ray diffraction (XRD), and Raman spectroscopy were used in conjunction with standard electrochemical techniques, including impedance spectroscopy. While electrodes comprised of synthetic flakes demonstrated impressive stability, even at 80°C, MCMB–MCF electrodes demonstrated a rapid capacity fading at elevated temperatures. This capacity fading is due to the formation of thick surface films that contain Li carbonate and Li oxalate as part of their components. The thick surface films are formed upon cycling because of the surface properties of round-shaped graphite particles, as discussed herein. The MCMB–MCF electrodes fail at high temperature because of the high impedance developed due to the formation of thick surface films.
Rich Mobile Applications (RMAs) comprise a budding research area receiving increasingly abundant attention from the academic and industrial communities. RMAs are deemed to be a candidate blueprint of future online smartphone applications aiming to deliver high functionalities and rich immersive experience to mobile users. RMAs are still in early stages and comprehensive survey of the domain is lacking. In this paper, we use structuralism and functionalism paradigms to analyze RMAs' origins, trends, and characteristics. RMAs are distinguished from traditional mobile applications and Rich Internet Applications (RIAs). Comprehending the distinction between delivering Rich User eXperience (RUX) in desktop and mobile computers, and the inward similarities and dissimilarities between RMAs and RIAs will facilitate and accelerate the development of rich, smartphone-centric applications. We analyze several problems inhibiting the adoption of RMAs and review corresponding solutions to devise a taxonomy. Our study advocates that the majority of problems stem from the intrinsic characteristics of mobile devices and the heterogeneity in this environment, especially when cloud computing is employed to enhance mobile computing. Several open issues on RMAs' domination and adoption are presented as future research directions.
A CoS2/graphene nanoarchitecture was synthesized by a facile one-step hydrothermal route using graphite oxide, thioacetamide, and CoCl2·6H2O as the starting materials. The growth of CoS2 and the reduction of the graphite oxide occur simultaneously. CoS2 nanocrystals with a size of 100−150nm are uniformly anchored on the both sides of the graphene nanosheets, forming a unique CoS2/graphene hybrid nanostructure. The electrochemical tests showed that the nanocomposite exhibits obviously enhanced Li-storage properties compared with bare CoS2. The improvement in electrochemical properties could be attributed to the formation of two-dimensional conductive networks, homogeneous dispersion and immobilization of CoS2 nanoparticles, and the enhanced wetting of active material with the electrolyte by in situ introduced graphene nanosheets.
LiNi0.5Co0.2Mn0.3O2 particles coated with lithium silicate were prepared via a precipitation method and their charge and discharge properties were investigated. The capacity retention and coulombic efficiency of the 0.5 wt% lithium silicate-coated LiNi0.5Co0.2Mn0.3O2 was improved at a high cut-off voltage of 4.6 V. Cross-sectional scanning electron microscope images revealed that extensive cracks were formed within the uncoated LiNi0.5Co0.2Mn0.3O2 particle along the grain boundaries after the charge and discharge cycling, while the crack generation was significantly inhibited for the coated particles. From cross-sectional transmission electron microscope analysis, it was shown that Si-rich regions were concentrated not only on the surface, but also at the grain boundaries even at a depth of 400 nm from the surface of the lithium silicate-coated sample. These results suggested that the Si-rich regions inhibited the crack formation and prevented the intrusion and the decomposition of the electrolyte solution within the particles. Consequently, lithium silicate coating is an effective way for improving the charge and discharge characteristics of LiNi0.5Co0.2Mn0.3O2.
Slurry preparation in a citric-acid-buffered aqueous solution at low pH has been established as a viable strategy for tackling the poor capacity retention of silicon electrodes. A number of studies ascribed the improved capacity retention to the formation of a silyl ester between the Si surface and carboxymethyl cellulose (CMC-Na). Most recent findings suggest that the citric acid itself interacts with the Si surface. Moreover, cross-linking reactions between the carboxylic acid and the binder can occur. In order to provide a comprehensive overview and to gain a better understanding of the reactions on the Si surface during slurry preparation, we review here previous results and interpretations and revisit earlier infrared (IR) studies, whose findings we link to our own IR studies of the impact of the slurry components, individually and combined. Specifically, we studied the interactions between the carboxylic acid, CMC-Na and Si particles, with the aim to clarify the effects of different amounts of carboxyl groups in carboxylic acids, namely glycolic, malic and citric acids with 1, 2 and 3 carboxyl groups, respectively. Furthermore, we demonstrate that the capacity retention of Si electrodes can be improved considerably with any of the acids studied.
Spin current is a central theme in spintronics, and its generation is a keen issue. The spin-polarized current injection from the ferromagnet, spin battery, and spin Hall effect have been used to generate spin current, but Ohmic currents in the normal state are involved in all of these methods. On the other hand, the spin and spin current manipulation by the supercurrent in superconductors is a promising route for dissipationless spintronics. Here we show theoretically that, in two-dimensional superconductors with Rashba spin-orbit interaction, the generation of dissipationless bulk spin current by charge supercurrent becomes highly efficient, exceeding that in normal states in the dilute limit, i.e. when the chemical potential is close to the band edge, although the spin density becomes small there. This result manifests the possibility of creating new spintronic devices with long-range coherence.
Au nano particles (NPs) were deposited on vertically grown TiO2 nanorod arrays on FTO substrate by hydrothermal process. Metal nanoparticles were loaded onto the surface of TiO2 nanorods via photochemical reduction process under ultraviolet irradiation. X-ray diffraction (XRD), electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis were used to characterize the as-prepared Au/TiO2 nanorod composites. Current density–voltage (J–V) measurements were obtained from a two-electrode sandwich type cell. The presence of Au nanoparticles can help the electron–hole separation by attracting photoelectrons. Addition of Au nanoparticles to the TiO2 nanorod significantly increased the fill factor and J SC (short circuit current density). The application of Au NPs TiO2 nanorods in improving the performance of DSSCs is promising.
Nowadays, the demand for high energy density, fast-charging and wide-temperature range lithium-ion batteries has increased significantly. The Solid Electrolyte Interphase (SEI) protecting layer, formed at the interface between the graphite anode and the electrolyte is a key parameter for fast kinetics and wide temperature operation, especially to enable fast charge of cells including graphite anodes. In this work, fluorosulfonyl isocyanate (FI) is used as a novel SEI film forming electrolyte additive for graphite anode. Due to its high reduction potential (above 2.8 V vs. Li+/Li), FI is reduced prior to the carbonate-based electrolyte, yielding a conductive SEI on the surface of the graphite. The SEI is made of a thick and protective inorganic inner layer that prevents the growth of the outer organic layer. As a result, the resistance of the graphite/electrolyte interface is dramatically decreased. Therefore, Li/graphite cells with 2 wt% FI exhibit excellent rate performance at room temperature (20 °C) and low temperature (0 °C and −20 °C), compared to those with the reference liquid electrolyte (LP30).
Carbon-doped TiO2 nanotubes were synthesized through a sol–gel and subsequent hydrothermal process. Transmission electron microscopy and X-ray diffraction showed that the products are uniformly straight tubes with the diameter around 10nm in anatase-type. The electrochemical performances of the nanotubes were tested by constant current discharge/charge, cyclic voltammetry, and electrochemical impedance spectroscopy. The initial discharge capacity reaches 291.7mAhg−1 with a coulombic efficiency of 91.7% at a current density of 70mAg−1. There is a distinct potential plateau near 1.75 and 1.89V (versus Li+/Li) in the lithium intercalation and extraction processes, respectively, and the lithium insertion capacity is about 204mAhg−1 over the plateau of 1.75V region in the first cycle. From the 2nd to the 30th cycles, the average reversible capacity loss is less than 1.73mAhg−1 per cycle. After 30 cycles, the reversible capacity still remains 211mAhg−1 with a coulombic efficiency larger than 99.7%, implying a perfect reversibility and cycling stability.
Taxanes represent a treatment of choice for metastatic breast cancer. Their combination with bevacizumab improved response rate and progression-free survival. We studied in vitro the effect on cell survival of the combination of either paclitaxel or nab-paclitaxel with bevacizumab and we investigated the biological factors involved in the response to treatments. We used two breast cancer cell lines, MCF7 (ER+/HER2-) and MDA-MB-231 (ER-/HER2-), co-cultured with or without HUVEC cells. We analysed cell survival by MTT test, VEGF secretion by ELISA and VEGFR, SPARC, MDR1 expression by western blot. Doses of both taxanes causing a 50 % growth inhibition were higher in MCF7 than MDA-MB-231, suggesting that taxanes are more effective in ER- cell lines. When both cell lines were grown as single culture, the combination bevacizumab+paclitaxel showed a similar anti-proliferative effect compared to paclitaxel alone. The association bevacizumab+nab-paclitaxel was more effective than nab-paclitaxel alone. An increased anti-proliferative effect of bevacizumab+paclitaxel was observed when MDA-MB-231 cells were cultured with HUVEC. We detected an induction of VEGF secretion when MDA-MB-231 cells were treated with either taxanes. Paclitaxel caused a reduction of VEGF in MCF7. SPARC resulted up-regulated in both cell lines treated with bevacizumab+nab-paclitaxel. Nab-paclitaxel seems to play an important role in inhibiting tumor proliferation through albumin-SPARC bound in association with bevacizumab compared to taxanes alone in both breast cancer cells. The addition of bevacizumab to paclitaxel increased its activity only in ER- cells. This difference might be due to their ER status.
Fe2O3-graphite (Fe2O3-G) composites have been facilely and effectively synthesized via ball milling. Structural features and electrochemical properties of the Fe2O3-G composites as anodes for lithium-ion batteries are investigated. The Fe2O3-G composites benefit from the close contact of nanocrystalline Fe2O3 with the graphite matrix, which improves the electronic conductivity and restrains the volume variation during cycling. The composite with 20% graphite shows the highest reversible capacity up to 491.1 mAh g−1 after 55 cycles with good rate capability. Due to the superior electrochemical performance, the Fe2O3-G composites prepared via ball milling could be promising as anode materials with high capacity, low-cost for lithium-ion batteries.
Porous NiCo2O4 hetero-structure arrays on nickel foam are prepared by a facile hydrothermal method. The morphology of the arrays changes with the growth time. After hydrothermal synthesis for 8 h in combination with annealing treatment, the NiCo2O4 array presents a nanoflake–nanowire hetero-structure. The porous NiCo2O4 hetero-structure array exhibits the excellent pseudocapacitive properties in 2 M KOH, with a high capacitance of 891 F g−1 at 1 A g−1 and 619 F g−1 at 40 A g−1 before activation as well as excellent cycling stability. The specific capacitance can achieve a maximum of 1089 F g−1 at a current density of 2 A g−1, which can still retain 1058 F g−1 (97.2% retention) after 8000 cycles. The enhanced pseudocapacitive performances are mainly attributed to its unique hetero-structure which provides fast ion and electron transfer, large reaction surface area and good strain accommodation.
A novel energy and cost effective transport chain for stranded natural gas utilized for power production with CO2 capture and storage is developed. It includes an offshore section, a combined gas carrier and an integrated receiving terminal. In the offshore section, natural gas (NG) is liquefied to LNG by liquid carbon dioxide (LCO2) and liquid inert nitrogen (LIN), which are used as cold carriers. In the onshore process, the cryogenic exergy in the LNG is utilized to cool and liquefy the cold carriers, LCO2 and LIN. The transport pressures for LNG, LIN and LCO2 will influence the thermodynamic efficiency as well as the ship utilization; hence sensitivity analyses are performed, showing that the ship utilization for the payload will vary between 58% and 80%, and the transport chain exergy efficiency between 48% and 52%. A thermodynamically optimized process requires 319kWh/tonne LNG. The NG lost due to power generation needed to operate the LEC processes is roughly one third of the requirement in a conventional transport chain for stranded NG gas with CO2 capture and sequestration (CCS).
The hydrothermal method was mostly used for the preparation of metallic double hydroxides. However, it is very time-consuming and energy-consuming. In this study, we for the first time reported a facile, rapid and cost-effective microwave strategy to fabricate nickel/cobalt double hydroxides (Ni/Co-DH). Four solvents, including water, ethanol, isopropanol and tertbutanol, were used for the synthesis of Ni/Co-DH to examine effect of the reaction medium. The study demonstrated that the Ni/Co-DH prepared in the aqueous solution exists as the mixture of α-Ni(OH)2 and β-Co(OH)2. However, the Ni/Co-DH prepared in the organic solvent studied has a hydrotalcite-like structure. Moreover, the Ni/Co-DH prepared in ethanol offers ultrathin flowercluster structure with a three-dimensional morphology. Owing to the greatly improved Faradaic redox reaction and mass transfer, the Ni/Co-DH electrode exhibits excellent pseudocapacitance performance, including high specific capacitance and rate capability, good charge/discharge stability and long-term cycling life. Its maximum specific capacitance was up to 1887.5Fg−1 at the current density of 1Ag−1, which is more than 2.4-fold that of the Ni/Co-DH prepared in the aqueous solution. The specific capacitance can remain 1187.5Fg−1 when the current density increases to 10Ag−1. The capacitance can keep at least 99.7% at the current density of 8Ag−1 after 3000 cycles. This work also provides a promising approach for the synthesis of various metallic double hydroxide materials with largely enhanced supercapacitor behavior, which can be potentially applied in energy storage/conversion devices.