batterydata/paper-abstracts huggingface dataset:
Nowadays, the hybrids of non-noble metal and heteroatom-doped carbon, especially, transition-metal-nitrogen-carbon materials, have been extensively studied as promising next-generation oxygen reduction reaction (ORR) catalysts in energy conversion. However, the pyrolysis of normal metal/nitrogen/carbon-containing precursors usually generates uncontrollable agglomeration or inhomogeneous microstructure, hence leading to insufficient exposure of the active sites and poor mass transport. In this work, a new strategy for fabricating N-doped-carbon-coated Fe3O4 (denoted as NC@Fe3O4) is proposed by the pyrolysis of polyaniline (PANI)-coated Fe-based metal organic frameworks (MIL-101-Fe). The optimal catalyst exhibits a very positive ORR onset potential close to that of Pt/C, quasi-four-electron-transfer pathway and high long-term cycle stability in alkaline media. This work demonstrates the crucial role of thin PANI film (a highly conductive skeleton and heteroatoms sources) together with MOFs to rationalize the superior ORR performance for the resulting NC@Fe3O4. The generality of the conductive-polymer-layer-assisted synthetic strategy is expected to further boost the electrocatalytic activity of universal non-noble-metal hybrid electrocatalyst for practical fuel-cell applications.
Solid oxide fuel cell concept was applied for Fe–air rechargeable battery by using H2/H2O as a mediator for Fe redox. Oxygen partial pressure in Fe set chamber during discharge was monitored simultaneously with O2 sensor for analysis of discharge mechanism. On the cell consisting of Pt anode, Y2O3 stabilized ZrO2(YSZ) electrolyte, and Pt cathode, 10 cycles of charge and discharge was stably performed, although decrease in capacity was observed at initial cycle. Oxygen partial pressure ( P O 2 ) was monitored by zirconia oxygen sensor which is used for Fe set chamber. Simultaneous monitoring the oxygen partial pressure during the charge and discharge, the reasonable response of P O 2 in Fe set chamber was observed and for discharge, Fe seems to be oxidized to FeO and reduction to Fe was also confirmed. Impedance plots suggested that degradation could be assigned to the increased diffusion overpotential because of the decreased oxidation rate of Fe powder. However, after second cycles, internal resistance of the cell was stable up to 10 cycles examined. Therefore, application of SOFC concept and H2/H2O redox mediator is successfully demonstrated for the Fe–air rechargeable battery.
This study discusses six common methodological limitations in screening for language delay (LD) as illustrated in 11 recent studies. The limitations are (1) whether the studies define a target population, (2) whether the recruitment procedure is unbiased, (3) attrition, (4) verification bias, (5) small sample size and (6) inconsistencies in choice of “gold standard”. It is suggested that failures to specify a target population, high attrition (both at screening and in succeeding validation), small sample sizes and verification bias in validations are often caused by a misguided focus on screen positives (SPs). Other limitations are results of conflicting methodological goals. We identified three such conflicts. One consists of a dilemma between unbiased recruitment and attrition, another between the comprehensiveness of the applied gold standard and sample size in validation and the third between the specificity of the gold standard and the risk of not identifying co-morbid conditions.
Osteoarthritis (OA) of the hip and knee are among the most common chronic conditions, resulting in substantial pain and functional limitations. Adequate management of OA requires a combination of medical and behavioral strategies. However, some recommended therapies are under-utilized in clinical settings, and the majority of patients with hip and knee OA are overweight and physically inactive. Consequently, interventions at the provider-level and patient-level both have potential for improving outcomes. This manuscript describes two ongoing randomized clinical trials being conducted in two different health care systems, examining patient-based and provider-based interventions for managing hip and knee OA in primary care.
Bio-drying has been applied to improve the heating value of municipal solid waste (MSW) prior to combustion. In the present study, evolution of heavy metals in MSW during bio-drying and subsequent combustion was studied using one aerobic and two combined hydrolytic–aerobic scenarios. Heavy metals were concentrated during bio-drying and transformed between different metal fractions, namely the exchangeable, carbonate-bound, iron- and manganese-oxides-bound, organic-matter-bound and residual fractions. The amounts of heavy metals per kg of bio-dried MSW transferred into combustion flue gas increased with bio-drying time, primarily due to metals enrichment from organics degradation. Because of their volatility, the partitioning ratios of As and Hg in flue gas remained stable so that bio-drying and heavy metal speciation had little effect on their transfer and partitioning during combustion. In contrast, the partitioning ratios of Pb, Zn and Cu tended to increase after bio-drying, which likely enhanced their release potential during combustion.
A topic such as legal issues in clinical research is expansive and cannot be fully explored in a few hours or even a few days. An attempt has been made in writing this chapter to focus on issues commonly encountered by, or of concern to, investigators in the clinical research environment. Issues include those related to (1) informed consent for standard and research care, (2) types of advance directives and other surrogate decision-making requirements, (3) involvement of children in research, (4) maintenance of adequate medical records, (5) protection of confidentiality, (6) liability of clinical researchers, (7) conflicts of interest, and (8) authorship and rights in data. Although some of the discussion focuses on laws, regulations, and/or policies applicable at federal research institutions (e.g., the National Institutes of Health Clinical Center), this chapter should be useful to investigators in other working environments.
A combined SOC (State Of Charge) and SOH (State Of Health) estimation method over the lifespan of a lithium-ion battery is proposed. First, the SOC dependency of the nominal parameters of a first-order RC (resistor-capacitor) model is determined, and the performance degradation of the nominal model over the battery lifetime is quantified. Second, two Extended Kalman Filters with different time scales are used for combined SOC/SOH monitoring: the SOC is estimated in real-time, and the SOH (the capacity and internal ohmic resistance) is updated offline. The time scale of the SOH estimator is determined based on model accuracy deterioration. The SOC and SOH estimation results are demonstrated by using large amounts of testing data over the battery lifetime.
Poly(vinylidene fluoride) with different contents (1–15 mass%) of clay minerals (kaolinite and halloysite) has been synthesized by solution-casting method to investigate the electroactive β-phase formation mechanism and the dielectric properties of the clay polymer nanocomposite (CPN) films. X-ray diffraction spectra, Fourier transform infrared spectroscopy, micro-Raman spectroscopy and differential scanning calorimetry confirmed the formation of electroactive β-phase in PVDF matrix after the addition of clay minerals. Field emission scanning electron microscope images showed interfacial interaction in CPN between the polymer matrix and the clay minerals resulting in enhanced electroactive β-phase nucleation and large dielectric constant of the CPN thin films.
The Li4Ti5O12/Ketjen Black composites are synthesized via a simple hydrothermal method. The materials are characterized by XRD, SEM, HR-TEM, EDS, galvanostatic charge/discharge test, CV and EIS. The results indicate that Li4Ti5O12 (LTO) particles grow both in the pores and on the surface of mesoporous Ketjen Black (KB) forming open conductive frameworks and the Ketjen Black works as host forthe growth of Li4Ti5O12 primary nanoparticles. The LTO/KB electrode is fabricated without extra carbon black conductive agents and exhibits excellent electrochemical performances, especially at low temperature. The improved performances can be attributed to the presence of mesoporous Ketjen Black conductive templates with high electronic conductivity and formed 3D frameworks beneficial to the lithium ion diffusion.
The present study focused on the mechanism subserving the production of kinematic patterns in 21 children with 22q11.2DS (mean age=9.6±1.9; mean FSIQ=73.05±10.2) and 21 age- and IQ-matched control children (mean age=9.6±1.9; mean FSIQ=73.38±12.0) when performing a visuo-manual tracking task in which they had to track a cursor rhythmically between 2 target zones. Children with 22q11.2DS moved faster (overall) and reached their maximum velocity sooner when compared to controls. However, the number of corrective submovements to attain the target did not differ. Children with 22q11.2DS seem to adopt a young ballistic movement strategy, with a fast ballistic first movement phase, followed by a second movement phase with very little online corrections to attain the target. Children with 22q11.2DS are not able to process the incoming feedback during the second movement phase to maximize the accuracy of the ongoing movement and use this phase to prepare the following. The fact that the parietal cortex and cerebellum are involved in action prediction and internal representation and are implicated in children with 22q11.2DS provides a possible neurological basis for their problems with prospective control and tracking behavior.
A series of LiNi0.5Mn0.5−x Co x O2 (0≤ x ≤0.5) compounds was prepared by a solid state reaction, and their structure, surface state and electrochemical characteristics were also investigated by XRD, XPS, EIS and charge–discharge cycling. The non-equivalent substitution of cobalt for manganese induced an increase in the average valence of nickel, thereby shrinking in the lattice volume. Moreover, Co non-equivalent substitution could not only reduce the impurity content but also significantly decreased the charge transfer resistance, thereby improving the rate capabilities.
Direct quantitative electroanalysis of submilligram quantities of nanoscale, high-surface-area electroactive powders is achieved by hand-pressing the solids onto the surface of a carbon–wax composite electrode. Since this ‘sticky carbon’ method does not require solvents or polymer binders to create electrode structures, such as cast films, one may now examine the innate electrochemical character of nanoscale materials. Electrode preparation with sticky carbon is rapid and simple and offers a convenient means to screen high-surface-area electrode materials whose inherently high RC time constants can compromise the resolution of the faradaic information. The effects on the electrochemical character of electrocatalysts, active materials in batteries, electrochromic materials, etc., of the common constituents (e.g. solvents, polymer binders, ionomers) and processes/forces (temperatures, pressures) necessary to create practical electrode structures may now be methodically explored.
This manuscript reports the performance of composite electrodes based on the mixture of two, electrochemically active, materials: lithium iron phosphate (LiFePO4) and activated carbon (AC). The sodium salt of carboxymethylcellulose (CMC) was used as binder to cast the composite electrodes out of aqueous slurries. The investigated electrodes display high specific capacity and high cycling stability. Upon constant current tests with a charge rate of 50C and a discharge rate of 1D, the electrodes display a capacity of ca. 70mAhg−1 while 60mAhg−1 are delivered during pulse sequence tests at 100C. These results indicate such electrodes as promising candidates for the realization of lithium-ion capacitors.
A pyrolyzed carbon and reduced graphene oxide co-doped LiMn0.9Fe0.1PO4 (LMFP/C/rGO) is synthesized by a novel and facile amine-assisted coating strategy. The well designed co-doped LiMn0.9Fe0.1PO4 nanoplate (LMFP/C/rGO, 150 nm in length and 20 nm in thickness) is proved to be olivine phase with good crystallinity which is further compared with the sole pyrolyzed carbon coated LiMn0.9Fe0.1PO4 (LMFP/C) from structural and electrochemical points of views. The LMFP/C/rGO exhibits superior electrochemical performances with the specific capacity of 158.0 mAh g−1 at 0.1C and 124.6 mAh g−1 at 20C, which is, to the best of our knowledge, the highest rate capability. Moreover, after 140 cycles at 0.2C rate, around 95% of the initial capacity is still retained. Further analyses disclosed the outstanding electrochemical performances can be ascribed to the collaboration of the uniformly coated pyrolyzed carbon and closely connected rGO with an extraordinary electronic conductivity. Our research shows this effective synthesis strategy is imperative for the improvement of Li-ion battery performance and can be widely used for advanced energy storage.
The present study reports on experimental investigations of the dynamic behavior of CO2 gas bubbles and the performance of a 9cm2 transparent direct methanol fuel cell (DMFC). The movement of CO2 gas bubbles in the anode channel subjected to a flow of aqueous methanol solution was visualized. A series of parametric studies was carried out to evaluate the effects on the CO2 gas bubbles dynamics as well as the cell performance. It was observed that the pores around the corner of the channel ribs and the intersection of the carbon cloth fibres were favorable sites for the emergence of CO2 gas bubbles. The growth and coalescence of CO2 gas bubbles resulted in gas slugs blocking the channel and the pores in porous diffusion layer as well. Then the gas slugs were pushed by the aqueous methanol solution flow to detach and sweep downstream, clearing all the existing small bubbles on the porous diffusion layer surface. The processes of emergence, growth, coalescence, detachment, and sweeping of the gas bubbles were found to occur periodically. High flow rates of the aqueous methanol solution resulted in small discrete CO2 gas bubbles and short gas slugs. Increasing temperature of the methanol solution increased the quantity of CO2 gas bubbles. More CO2 gas bubbles and large gas slugs appeared in the channels with increasing pressure difference between the anode and the cathode. The cell performance was improved with increasing aqueous methanol flow rates, feed temperature, feed concentration, and the pressure difference between the anode and the cathode.
The capability to adjust the properties of ILs by combining different cations and anions leads to the name of “designer solvents” for ILs. There is a steadily growing interest for the use of ILs in electrochemical applications such as supercapacitors and rechargeable batteries. In this work, the highly parameterized, empirical exchange–correlation functional at M06–2X/6-311++G(d,p) level of theory were employed to investigate the influence of various cations and anions on electrochemical and physicochemical properties of the thirty-six ILs formed from a combination of para−X−phenyl methylimidazolium ([X−PhMIM]+: X=NH2, OH, OCH3, CH3, H, F, CHO, CN and NO2) cations and the four different conventional anions (Y1–4 =CH3COO−, NO3 −, BF4 − and PF6 −). The potentials of the cathodic (VCL) and anodic (VAL) limits, electrochemical windows (ECW), CT values, volumetric and thermodynamic properties, interaction energy, enthalpy of formation of cations, Gibbs free solvation energy, topological properties and NMR one- and two bonds spin–spin coupling constants (SSCCs) were predicted.
The Impact Factor of a journal (that is usually made available every year in June) is essentially dependent on the most cited papers published in the first of the two years period over which citations are reckoned. Therefore, the Impact Factor for 2005 is mainly dependent on the citations collected by the papers published in 2003. In this respect, the Editors of Electrochimica Acta are pleased to list below the papers appeared in the journal in 2003 that have received thus far the highest number of citations, thus contributing essentially to establish the value of the IF. Congratulations to the Authors!The most cited papers of 2003Y. Zhang, S. Asahina, S. Yoshihara, T. Shirakashi, Oxygen reduction on Au nanoparticle deposited boron-doped diamond films, Electrochimica Acta 48 (6), 741–747.H.G. Herz, K.D. Kreuer, J. Maier, G. Scharfenberger, M.F.H. Schuster, W.H. Meyer, New fully polymeric proton solvents with high proton mobility, Electrochimica Acta 48 (14–16 SPEC.), 2165–2171.N. Dimov, S. Kugino, M. Yoshio, Carbon-coated silicon as anode material for lithium ion batteries: advantages and limitations, Electrochimica Acta 48 (11), 1579–1587. Sergio Trasatti Editor-in-Chief
A 5-cubic meter decompression chamber was re-purposed as a fire test chamber to conduct failure and abuse experiments on lithium-ion batteries. Various modifications were performed to enable remote control and monitoring of chamber functions, along with collection of data from instrumentation during tests including high speed and infrared cameras, a Fourier transform infrared spectrometer, real-time gas analyzers, and compact reconfigurable input and output devices. Single- and multi-cell packages of LiCoO2 chemistry 18650 lithium-ion batteries were constructed and data was obtained and analyzed for abuse and failure tests. Surrogate 18650 cells were designed and fabricated for multi-cell packages that mimicked the thermal behavior of real cells without using any active components, enabling internal temperature monitoring of cells adjacent to the active cell undergoing failure. Heat propagation and video recordings before, during, and after energetic failure events revealed a high degree of heterogeneity; some batteries exhibited short burst of sparks while others experienced a longer, sustained flame during failure. Carbon monoxide, carbon dioxide, methane, dimethyl carbonate, and ethylene carbonate were detected via gas analysis, and the presence of these species was consistent throughout all failure events. These results highlight the inherent danger in large format lithium-ion battery packs with regards to cell-to-cell failure, and illustrate the need for effective safety features.
Understanding charge carrier transport in Li2O2, the storage material in the non-aqueous Li-O2 battery, is key to the development of this high-energy battery. Here, we studied ionic transport properties and Li self-diffusion in nanocrystalline Li2O2 by conductivity and temperature variable 7Li NMR spectroscopy. Nanostructured Li2O2, characterized by a mean crystallite size of less than 50 nm as estimated from X-ray diffraction peak broadening, was prepared by high-energy ball milling of microcrystalline lithium peroxide with μm sized crystallites. At room temperature the overall conductivity σ of the microcrystalline reference sample turned out to be very low (3.4 × 10−13 S cm−1) which is in agreement with results from temperature-variable 7Li NMR line shape measurements. Ball-milling, however, leads to an increase of σ by approximately two orders of magnitude (1.1 × 10−10 S cm−1); correspondingly, the activation energy decreases from 0.89 eV to 0.82 eV. The electronic contribution σeon, however, is in the order of 9 × 10−12 S cm−1 which makes less than 10% of the total value. Interestingly, 7Li NMR lines of nano-Li2O2 undergo pronounced heterogeneous motional narrowing which manifests in a two-component line shape emerging with increasing temperatures. Most likely, the enhancement in σ can be traced back to the generation of a spin reservoir with highly mobile Li ions; these are expected to reside in the nearest neighbourhood of defects generated or near the structurally disordered and defect-rich interfacial regions formed during mechanical treatment.
Directed self-guidance, whereby trainees independently practice a skill-set in a structured setting, may be an effective technique for novice training. Currently, however, most evaluation methods require an expert to be present during practice. The study aim was to determine if absolute symmetry error, a clinically important measure that can be assessed by the trainee, is a feasible assessment tool for self-guided learning of suturing skill. Forty-eight undergraduate medical trainees independently practiced suturing and knot tying skills using a benchtop model. Performance on a pretest, posttest, retention test and a transfer test was assessed using (1) the validated final product analysis (FPA), (2) the surgical efficiency score (SES), a combination of the FPA and hand motion analysis and (3) absolute symmetry error, a new measure that assesses the symmetry of the final product. Absolute symmetry error, along with the other objective assessment tools, detected improvements in performance from pretest to posttest (P < 0.05). A battery of correlation analyses indicated that absolute symmetry error correlates moderately with the FPA and SES. The development of valid, reliable and feasible technical skill assessments is needed to ensure all training centers evaluate trainee performance in a standardized fashion. Measures that do not require the use of experts or computers have potential for widespread use. We suggest that absolute symmetry error is a useful approximation of novices’ suturing and knot tying performance. Future research should evaluate whether absolute symmetry error can enhance learning when used as a source of feedback during self-guided practice.
Electroless chemical aging of commercially available, porous carbon felt electrodes for the all-vanadium redox flow battery (VRFB) was investigated by full-cell and half-cell measurements in a beaker set-up and a cell with flow-through geometry at different states of charge and different temperatures. Changes in the charge transfer resistance and the double layer capacitance due to chemical aging were determined by electrochemical impedance spectroscopy (EIS) and correlated with ex-situ X-ray photoelectron spectroscopy (XPS). EIS measurements revealed that the aging of the carbon electrodes was dependent on the temperature for low vanadium concentrations and independent on the temperature for high vanadium concentrations. This indicates that the electroless aging of the electrodes occurs due to a chemical reaction with the sulfuric acid and with the vanadium. XPS measurements revealed an increase of the amount of surface functional groups on the carbon felt electrodes by a factor of 1.5 to 1.8 after 8days of mere contact with electrolyte. Moreover, the conducting sp2-hybridized layer was diminished by a factor of 2 or more. It appears that the negative half-cell [V(II)/V(III)] is more strongly affected by chemical aging than the positive half-cell [V(IV)/V(V)]. Electroless aging was found to be inevitable for all the carbon felts used.
Graphene supercapacitors with a high electrode surface area have great potential in efficient energy storage. For practical applications, it is critical to develop highly-manufacturable methods to synthesize graphene nanosheets with high ion accessibility and uniform pore-sizes. Here we demonstrate a nontoxic approach for graphene synthesis which involves a low vacuum annealing at an easy-to-reach temperature. The supercapacitors based on the low-temperature exfoliated graphene materials show excellent electrochemical performance superior to those synthesized by high-temperature methods. Our investigation presents an efficient, yet industry-compatible and low cost way that can be scaled up for mass production of graphene for electrochemical energy storage application.