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We introduce high-performance polyaniline (PANI) nanocomposite supercapacitors based on gamma aluminum oxide (γ-Al2O3) and gamma iron (III) oxide (γ-Fe2O3) nanoparticles with a high specific surface area. PANI and its polymer nanocomposites are synthesized via in situ electropolymerization on gold electrodes. The structures and morphologies are characterized by cyclic voltammetry, FT-IR spectroscopy, SEM, TEM, and EDX. The electrochemical properties and specific surface area of the electrodes are investigated by galvanostatic charge–discharge, electrochemical impedance spectroscopy (EIS) and BET theory. The enhanced specific capacitance with higher surface area and conductivities is observed in PANI/γ-Fe2O3 (342F/g), PANI/γ-Al2O3 (292F/g) and PANI (180F/g) electrodes with a constant current density of 1A/g. The cyclic performance of the PANI electrodes following 8000cycles of operations were at 87% (PANI), 91% (PANI/γ-Al2O3), and 93% (PANI/γ-Fe2O3) of their initial capacitance. In addition, higher specific capacitances, higher conductivity and cyclic self-stabilities observed for the PANI/nanocomposite electrodes can provide new opportunities in the field of energy storage and supercapacitor applications.
To demonstrate calpain involvement in neurodegeneration in rat spinal cord injury (SCI), we examined SCI segments for DNA fragmentation, neurons for calpain overexpression, neuronal death, and neuroprotection with calpain inhibitor (E-64-d). After the induction of SCI (40 g cm force) on T12, rats were treated within 15 min with vehicle (DMSO) or E-64-d. Sham animals underwent laminectomy only. Animals were sacrificed at 24 h, and five 1-cm long spinal cord segments were collected: two rostral (S1 and S2), one lesion (S3), and two caudal segments (S4 and S5). Agarose gel electrophoresis of DNA samples isolated from the SCI segments showed both random and internucleosomal DNA fragmentation indicating occurrence of necrosis as well as apoptosis mostly in the lesion, moderately in caudal, and slightly in rostral segments from SCI rats. Treatment of SCI rats with E-64-d (1 mg/kg) reduced DNA fragmentation in all segments. The lesion and adjacent caudal segments (S3 and S4) were further investigated by in situ double-immunofluorescent labelings that showed increase in calpain expression in neurons in SCI rats and decrease in calpain expression in SCI rats treated with E-64-d. In situ combined TUNEL and double-immunofluorescent labelings directly detected co-localization of neuronal death and calpain overexpressin in SCI rats treated with only vehicle while attenuation of neuronal death in SCI rats treated with E-64-d. Previous studies from our laboratory indirectly showed neuroprotective effect of E-64-d in SCI rats. Our current results provide direct in situ evidence for calpain involvement in neuronal death and neuroprotective efficacy of E-64-d in lesion and penumbra in SCI rats.
ABSTRACT Electric drive vehicles (EDVs) must incorporate thermal management systems for powertrain-related subsystems, including the power electronics, electric motors, and energy storage system (ESS) as well as the passenger compartment. Multiple independent heating and cooling loops reduce the effectiveness of fuel-saving control strategies, increase weight and volume, and reduce all-electric range. Building on the National Renewable Energy Laboratory's (NREL's) extensive experience, integrated thermal management concepts in an overall vehicle context are being investigated. The initial results of the air conditioning (A/C), passenger compartment, and power electronics KULI models of an electric vehicle (EV) are described. Various concepts for combining the systems will be assessed and the performance compared to a baseline system.
A Li4Ti5O12(LTO)/N-doped reduced graphene oxide (RGO) composite is proposed using dual functional nitrogen doping source to prevent RGO restacking and achieve uniform nitrogen doping on RGO sheets to increase the rate performance of high-rate lithium ion batteries. The pore structure (both meso- and macro pores) is developed when RGO restacking is prevented, facilitating electrolyte ion diffusion to active sites with lower resistance. Uniform nitrogen doping on RGO sheets with high nitrogen contents provides additional free electrons to the sheets, resulting in increased electronic conductivity. Cyanamide is used as the nitrogen doping source for the N-doped RGO as well as a nanospacer between the RGO sheets. In the composite, the nitrogen content of the RGO sheets is 2.3 wt%, which increases the electronic conductivity of the composite to 1.60 S cm−1. The specific surface area of the composite is increased to 35.8 m2 g−1. Thus, the composite structure with the N-doped RGO sheets and porous secondary particles has high electrical conductivity and high ion accessibility. The LTO/N-doped RGO composite demonstrates excellent electrochemical performance with a low resistance of 48.4 Ω, a high specific capacity of 117.8 mAh g−1 at 30 C, and good cycle stability.
The microstructures of a series of AB2-based metal hydride alloys (Ti12.5Zr21V10Cr8.5Mn x Co1.5Ni46.5−x ) designed to have different fractions of non-Laves secondary phases were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, and electron backscatter diffraction. The results indicate that the alloys contain a majority of hydrogen storage Laves phases and a minority of fine-structured non-Laves phases. Formation of the phases is accomplished by dendritic growth of a hexagonal C14 Laves phase. The C14 phase is followed by either a peritectic solidification of a cubic C15 Laves phase (low Mn containing alloys) or a C14 phase of different composition (high Mn containing alloys), and finally a B2 phase formed in the interdendritic regions (IDR). The interdendritic regions may then undergo further solid-state transformation into Zr7Ni10-type, Zr9Ni11-type and TiNi-type phases. As the Mn content in the alloy increases, the fraction of the C14 phase increases, whereas the fraction of C15 decreases. In the IDRs when the alloy's Mn content increases the Zr9Ni11 phases and Zr7Ni10 phase fraction first increases and then decreases, while the TiNi-based phase fraction first increases and then stabilized at 0.02. IDR compositions can be generally expressed as (Ti,Zr,V,Cr,Mn,Co)50Ni50, which accounted for 7–10% of the overall alloy volume fraction.
Self-compassion has been theorized to have three components, each with a positive pole and a negative pole: self-kindness versus self-judgment, common humanity versus isolation, and mindfulness versus over-identification. Neff (Self Identity 2:85–101, 2003a) proposes that they mutually influence each other, however, this proposition has not been tested yet. We conducted a pilot study to see if improvements from training one component spilled over to the other two—and whether these trainings had an impact on well-being. 80 participants completed 8 weeks of self-compassionate writing exercises to enhance either self-kindness, common humanity, or mindfulness. Trait self-compassion was assessed using the six-factor model of the self-compassion scale. To address issues of alpha-error-inflation, the false discovery rate was fixed at 5%, and critical p values were adjusted accordingly. Participants in the mindfulness condition reported increased total self-compassion (p = .009), which was accompanied by increased self-kindness (p = .027) and lower isolation (p = .045). Participants in the common humanity condition reported improved total self-compassion (p = .018), lower over-identification (p = .045), and higher life-satisfaction (p = .049). The training in self-kindness failed to improve self-kindness or any other factor. These findings provide initial evidence that the components of self-compassion mutually enhance each other. They also emphasize the importance of mindfulness within the conceptualization of self-compassion.
A simple acid leaching technique is demonstrated to produce λ-MnO2 by treating LiMn2O4 with H2SO4. λ-MnO2 shows high intercalation capacities as the positive electrode material for rechargeable aqueous batteries. The structure and morphology of the nano-particles are characterized by X-ray power diffraction, inductively coupled plasma, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy. The electrochemical performance of λ-MnO2 is investigated by cyclic voltammetry, constant current charge-discharge tests and electrochemical impedance spectroscopy. λ-MnO2 has ideal battery behaviors for polyvalent cations (Mg2+, Zn2+) to intercalate/deintercalate in the aqueous electrolyte. The λ-MnO2 electrode shows a high initial discharge capacity of 545.6 mAh g−1 at 13.6mAg−1 in 0.5mol dm−3 MgCl2 with a columbic efficiency of nearly 100%. In addition, it shows good cycling stability and maintains a capacity of 155.6 mAh g−1 after 300 cycles in 1mol dm−3 MgCl2 electrolyte.
A polypyrrole (Ppy) film has been deposited on a Ni electrode by anodic polymerisation from acetonitrile solutions. X-ray photoelectron spectroscopy (XPS) analysis shows nickel Ni2+ chemically bound to the polymer chain. Impedance spectroscopy has been employed to characterise this new material in a system of metal/film/electrolyte in a frequency range 105/10−2 Hz. The ac response of the film consists of four or three separable elements depending on the film’s thickness. Incorporation of nickel ions into electronically conducting polymer causes, (i) negligible changes in a polymer redox resistance (high frequency response); (ii) considerable decrease of conductivity responding to ac signal at medium frequency; (iii) linear dependence between resistance measured at medium frequency of ac signal and electrode potential appeared to be caused by nickel presence in the film. Effective diffusion coefficient established for Ppy layers on Ni, Pt and stainless steel at OCV potentials are 1.2×10−10, 1.0×10−8, and 2.2×10−9 cm2 s−1, respectively.
Thin porous binder-free layers of Co hydroxide/oxide for electrochemical capacitors were formed by dealloying an electrochemically deposited binary Zn–Co alloy, consisting of single homogeneous γ-Zn21Co5 phase. Scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy (XPS) was used to assess the structure, thickness, and distribution of elements in the as-deposited alloy and the dealloyed layers. The most developed porous layers were formed at a dealloying potential of − 0.965 V versus Ag/AgCl. Both the as-deposited Zn–Co and the dealloyed layers were characterized by a relatively uniform distribution of the components. As determined by XPS, the top of the dealloyed layers before cycling consisted of Co(II) hydroxide with traces of Co(0) and Co(III). The capacitive properties and stability of the formed layers of porous Co oxides were assessed using the electrochemical cyclic voltammetry (CV) and the constant current charge–discharge (C–D) methods. The areal and volumetric pseudo-capacitance values of ~ 0.38 F cm−2 and ~ 880 F cm−3, respectively, were calculated for a 4.3-µm-thick layer. The stability of the studied Co hydroxide/oxides layers was evaluated by CV and C–D cycling. After 300 cycles of C–D, the retention of pseudo-capacitance ~ 80% and the Coulombic efficiency of ~ 98% were determined. The long-term pseudo-capacitance retention was estimated at ~ 78.3% of the initial value.
The shuttling effect of soluble polysulfide in electrolyte has been the major obstacle resulting in the poor cycling stability of Li–S battery. The ultrathin ZrB2/graphene oxide/carboxymethocel (ZrB2/GO/CMC) layer coated onto cathode via simple doctor blade method has been developed as the effective polysulfide shuttling barrier. Owing to typical 2D scaffold and abundant functional oxygen groups，the GO can provide physical defender as well as chemical trap against polysulfide shuttling. The introduction of conductive ZrB2 nanoparticles in the hybrid layer can not only improve the conductivity of hybrid layer dramatically reducing electrochemical polarization of Li–S battery without adding other conductive agent but also further form chemical shield by chemisorption which is firstly confirmed by experimental and theoretical calculations. Combining these merits, the ultrathin ZrB2/GO/CMC hybrid layer combining with CNT@S hybrid cathode enables the Li–S battery to achieve good rate performance (769 mAh g−1 at a rate of 2 C) and stable cycling capability (with a low capacity decay rate of 0.098% during 300 cycles at 1 C). Specifically, the Li–S battery shows the potential of practical application, with high areal S loading of 5.1 mg cm−2, delivering the capacity near-commercial lithium-ion battery.
Predicting the responses of animals to environmental changes is a fundamental goal of ecology and is necessary for conservation and management of species. While most studies focus on relatively gradual changes, extreme events may have lasting impacts on populations. Animals respond to major disturbances such as hurricanes by seeking shelter, migrating, or they may fail to respond appropriately. We assessed the effects of Hurricane Irma in 2017 on the behavior and survival of juvenile bull sharks (Carcharhinus leucas) within a nursery of the Florida coastal Everglades using long-term acoustic telemetry monitoring. Most of our tagged sharks (n = 14) attempted to leave the shallow waters of the Shark River Estuary before the hurricane strike, but individuals varied in the timing and success of their movements. Eight bull sharks left within hours or days before the hurricane, but three left more than a week in advance. Nine of 11 bull sharks (~ 82%) eventually returned to the array within weeks or months of the storm. Six of these returning individuals were detected in a different coastal array in nearshore waters ca. 80 km away from the mouth of the estuary during their absence. The remaining three bull sharks moved downstream relatively late (after the hurricane) and may have died. We used binomial generalized linear mixed models to estimate the probability of presence within the array as a function of several environmental variables. Departure from the array was predicted by declining barometric pressure, increasing rate of change in pressure, and potentially fluctuations in river stage. Juvenile bull sharks may weigh multiple environmental cues, perceived predation risk, their own physical size, and shifting prey resources when making decisions during and after hurricanes.
Microgrids are a suitable, reliable and clean solution to integrate distributed generation into the mains grid. Microgrids can present both AC and DC distribution lines. The type of distribution conditions the performance of distribution line and implies different features, advantages and disadvantages in each case. This paper analyses, in detail, all this parameters for AC and DC microgrids in order to identify and describe the available alternatives for building and configuring a microgrid. Elements and issues involved in the implementation and development, such as protections, power converters, economic analysis, and availability are discussed and described. This analysis constitutes a tool for selecting a suitable configuration of a microgrid adapted to the needs in each situation. In addition, the paper provides a picture of the current situation of microgrids, and identifies and proposes future research lines.
A planar cell design for free-breathing fuel cell is studied. The cathode side of the cell was directly open to ambient air in a way that oxygen needed by the fuel cell reaction was provided by diffusion through the cathode side gas diffusion backing, i.e. the cell had no cathode side flow channels. The aim of the study was to demonstrate the feasibility of the cell concept by experimentally evaluating its performance with polarisation and current transient measurements. The orientation of the cell did not significantly affect the performance of the cell and signs of flooding were not observed. The maximum power density achieved in the polarisation measurements was ∼124mWcm−2. The current transient measurements revealed that with a small base load the cell is capable of producing momentarily current densities up to 500mAcm−2. The maximum transient power density achieved was ∼194mWcm−2 at transient current density of 450mAcm−2. According to the results it seems that this kind of cell design is feasible for small-scale applications, such as portable computers.
Well-defined star shaped polymers with α-Cyclodextrin (α-CD) core linking PMMA-block arms were synthesized by atom transfer radical polymerization (ATRP). Gel polymer electrolytes (GPEs) were prepared by encapsulating electrolyte solution of 1 mol L−1 of LiClO4/EC-PC (volume 1:1) into the obtained star shaped polymer host. The ionic conductivity of the GPEs and the cycling characteristics of LiCoO2/GPEs/Graphite cell were studied by electrochemical impedance spectroscopy and charge-discharge testing, respectively. The results indicate that the GPEs have a high ionic conductivity up to 1.63 × 10−3 S cm−1 at room temperature and exhibit a high electrochemical stability potential of 4.5 V (vs. Li/Li+). The discharge capacity of LiCoO2/GPEs/Graphite cell is about 98% of its initial discharge capacity after 20 cycles at 0.1 C rate. Discharge capacity of the model cell with GPEs is stable with charge-discharge cycling.
Nanostructured materials have attracted much attention in electrochemical energy storage and conversion (EESC) technologies such as batteries, fuel cells and supercapacitors. In particular, ordered arrays of one-dimensional (1D) nanorods/nanowires, and nanotubes, two-dimensional (2D) nano-thin sheets and three-dimensional (3D) nano-architectures, etc. have aroused great interest due to their unique intrinsic properties and much improved performances in EESC. Among various synthetic routes for these ordered nanostructures, ordered nanoporous anodic aluminum oxide (AAO) template assisted method has drawn particular attention because of AAO template’s outstanding chemical and thermal stability, easy fabrication process, hardness, cost-effective, versatility and high surface area. This review begins with the introduction on the basic structures and properties of the porous AAO templates, and then mainly summarizes recent progress in the AAO-template directed growth of various 1D, 2D and 3D ordered nanostructure arrays for applications in typical EESC systems, including lithium-ion batteries (LIBs), lithium-sulfur (Li-S) batteries, lithium-oxygen (Li-O2) batteries, supercapacitors and fuel cells, followed by outlook for future research.
Once Li+ ions start mobilizing, the crystalline active particles will persistently endure the internal stresses, which originate from the lattice deformation and will remain until reaching a new equilibrium state. While it is still lack of the fundamental understanding on this effect although the particle cracking has been accepted as a failure mode. Here we demonstrate the degradation of particles' mechanical properties and their influence on cathodes' electrochemical performances with a commercial ∼4 μm LiNi1/3Co1/3Mn1/3O2 single-crystals as the sample materials to simplify the model. As Li+ ions reciprocating, the particle strains induce the generation of the line dislocations and accordingly the aggrandization of these bulky defects, and then eventually lacerate the particles mainly along the (110) plane, which is the cleavage plane for the layer oxides. In the selected tested points, the particle cracking is always accompanied with the inflexion of cyclic stability. Obviously, the crystalline’ fracture-strength is gradually fatigued in every cycle, and eventually can't sustain the internal stress to result in the particle cracking and cyclic-stability plummet, similar to ‘constant dripping wears away a stone’ . Our approaches demonstrate that the crystalline active materials are suitable to the fracture-damage model, which is another principle for predicting the maximum of LIB's operational life.
Child labor is a prevalent global public health and human rights problem. It puts children at risk for acute and chronic health problems, in many cases prevents completion of formal education, and thwarts the right to freely choose economic opportunities. According to UNICEF, 218million children between the ages of 5 and 17years are classified as child laborers, and of these, 126million are engaged in what the International Labor Organization calls the worst forms of child labor. This article will review the types of child labor, the health effects, human rights principles and international law, and what public health professionals can do to mitigate this problem.
High voltage property applied in cells is one of the critical directions for high energy density lithium-ion battery. In this work, cadmium oxides are used as the modifying material on the LiNi0.6Co0.2Mn0.2O2 cathode materials by a facile chemical precipitation method followed by post-calcination. The cadmium oxides not only cover on the LiNi0.6Co0.2Mn0.2O2 particles surface homogenously, but also diffuse into the crystal lattice of the LiNi0.6Co0.2Mn0.2O2 with gradient distribution. The formed cadmium oxide and metal fluorides mixed-layer during cycling on the surface makes the interfacial stability significantly improved. Therefore, the side-reactions are suppressed effectively. The gradient doping of the cadmium in the crystal lattice enhances the structural stability of the LiNi0.6Co0.2Mn0.2O2 and facilitates the Li+ and electron transportation in the bulk material. Moreover, the residual lithium components (Li2CO3/LiOH) also decrease significantly. As a result, the obtained Cd-modified LiNi0.6Co0.2Mn0.2O2 cathodes rise 16.60 (100 cycles, 3.0–4.6 V) and 13.87 (200 cycles, 3.0–4.5 V) percentage points at 1 C rate, respectively. The initial capacity of cadmium-modified LiNi0.6Co0.2Mn0.2O2 is 160.8 mAh g−1 at 8 C rate over 3.0–4.5 V. The proposed cadmium oxide modification may be also potentially applied in other active cathode materials, especially for the high voltage performance.
The effect of PTFE addition was investigated for the electrophoretic deposition (EPD) of hydrous ruthenium oxide electrodes. Mechanical stability of electrode layers, together with deposition yield, was enhanced by using hydrous ruthenium oxide/PTFE dispersions. High supercapacitor performance was obtained for the electrodes prepared with 2% PTFE and 10% water. When PTFE content was higher, the rate capability became poor with low electronic conductivity; higher water content than 10% resulted in non-uniform depositions with poor cycleability and power capability. When electrodes were heat treated at 200°C for 10h, the specific energy was as high as 17.6Wh/kg based on single electrode (at 200W/kg); while utilizable energy was lower with heat treatment time of 1 and 50h, due to the high resistance and gradual crystallization, respectively. With PTFE addition and heat treatment at 200°C for 10h, the specific capacitance was increased by 31% (460→599F/g at ca. 0.6mg/cm2) at 10mV/s, and the deposition weight was increased up to 1.7mg/cm2 with initial capacitance of 350F/g.
In this study, the electrochemical performances of the novel glass fiber separators coated with potassium functionalized graphene (K-FGF) doped with polyaniline (PANI), poly 1,5-diaminoanthraquinone (PDAAQ) and PDAAQ/multi wall carbon nanotubes (MWCNT)/cetyltrimethyl-ammonium-bromide (CTAB) were evaluated for their ability of polysulfide entrapment to improve the cycling stability and the capacity fading rate. The test results showed that K-FGF coated glass fiber separator doped with PDAAQ and PDAAQ/MWCNT/CTAB displayed incredible improvement in the electrochemical performance of the battery, with high initial capacity of 1346 and 1361 mAh g− 1 and capacity retention of 804 and 968 mAh g− 1 after 200 cycles respectively. It is evident that PDAAQ suppresses the polysulfides shuttle in the electrolyte and offers a strong binding energy for the adsorption of polysulfides on the separator surface.