batterydata/paper-abstracts huggingface dataset:
We have investigated the reaction mechanisms occurring upon the first discharge/charge cycle of a MnSn2//Li electrochemical cell, by using bulk- and surface-sensitive characterization techniques (X-ray Diffraction, 119Sn Mössbauer spectroscopy, magnetic measurements, X-ray photoelectron and Auger spectroscopies). Compared to other tin-transition metal alloys, MnSn2 displays an original behaviour. Lithium insertion into MnSn2 particles results in a nanocomposite consisting of Li7Sn2 phase, and of Mn nanoparticles which are immediately oxidized at their surface. Lithium extraction from this nanocomposite leads to the formation of magnetic MnSn2 particles and to our knowledge it is the first time such a mechanism is observed in tin-based intermetallic electrode materials due to electrochemical reaction with Li. The solid electrolyte interphase (SEI) is formed at the beginning of the first discharge and its thickness slightly increases upon further lithium insertion. A partial re-dissolution process occurs upon lithium extraction from the material, while its chemical composition is very stable over the whole cycle.
Shuttle of polysulfide from the sulfur cathode to lithium metal anode in rechargeable lithium–sulfur batteries is a critical issue hindering cycling efficiency and life. Several approaches have been developed to minimize it including polysulfide-blocking separators; there is a need for measuring polysulfide transport through separators. We here show a linear voltage sweep method to measure anodic (oxidization) current of polysulfide crossed separators, which can be used as a quantitative measurement of the polysulfide transport. The electrochemical oxidation of polysulfide is diffusion controlled. The electrical charge in Coulombs produced by the oxidation of polysulfide is linearly related to the concentration of polysulfide within a certain range (≤0.5 M). Separators with a high porosity (large pore size) show high anodic currents, resulting in fast capacity degradation and low Coulombic efficiencies in Li–S cells. These results demonstrate this method can be used to correlate the polysulfide transport through separators with the separator structure and battery performance, therefore provide guidance for developing new separators for lithium–sulfur batteries.
CuCrO2/Ag2O composites are facilely prepared by chemical deposition of Ag2O on CuCrO2. After coating, the resulting Ag2O nanoparticles are uniformly dispersed on the surface of CuCrO2. Electrochemical results reveal that Ag2O coated CuCrO2 anode materials can display an improved reversible capacity of 405.4mAhg−1 at a current density of 50mAg−1 within the potential range of 0.0–3.0V, which is much higher than the value (230.4mAhg−1) released by pure CuCrO2. In addition, Ag2O enhanced CuCrO2 composites exhibit remarkable cycling stability by retaining a coulombic efficiency of 97.6% after 20cycles. The excellent electrochemical properties reveal that the Ag2O coating layer can effectively improve the cycling stability, reversible capacity and cycling efficiency of CuCrO2.
Neurocognitive heterogeneity is increasingly recognized as a valid phenomenon in ADHD, with most estimates suggesting that executive dysfunction is present in only about 33%–50% of these children. However, recent critiques question the veracity of these estimates because our understanding of executive functioning in ADHD is based, in large part, on data from single tasks developed to detect gross neurological impairment rather than the specific executive processes hypothesized to underlie the ADHD phenotype. The current study is the first to comprehensively assess heterogeneity in all three primary executive functions in ADHD using a criterion battery that includes multiple tests per construct (working memory, inhibitory control, set shifting). Children ages 8–13 (M = 10.37, SD = 1.39) with and without ADHD (N = 136; 64 girls; 62% Caucasian/Non-Hispanic) completed a counterbalanced series of executive function tests. Accounting for task unreliability, results indicated significantly improved sensitivity and specificity relative to prior estimates, with 89% of children with ADHD demonstrating objectively-defined impairment on at least one executive function (62% impaired working memory, 27% impaired inhibitory control, 38% impaired set shifting; 54% impaired on one executive function, 35% impaired on two or all three executive functions). Children with working memory deficits showed higher parent- and teacher-reported ADHD inattentive and hyperactive/impulsive symptoms (BF10 = 5.23 × 104), and were slightly younger (BF10 = 11.35) than children without working memory deficits. Children with vs. without set shifting or inhibitory control deficits did not differ on ADHD symptoms, age, gender, IQ, SES, or medication status. Taken together, these findings confirm that ADHD is characterized by neurocognitive heterogeneity, while suggesting that contemporary, cognitively-informed criteria may provide improved precision for identifying a smaller number of neuropsychologically-impaired subtypes than previously described.
A new type of hierarchical tin@carbon composite composed of graphene carbonaceous matrix and well-confined tin nanoparticles with a typical size of ~15nm (denoted as F-G/Sn@C) is developed and investigated as anode material for Li-ion and Na-ion storage. The two dimensional graphene backboned matrix not only acts as a confinement layer preventing the tin nanoparticles from aggregating during the material preparation, but also functions as a physical barrier to buffer the volume change effect during charge/discharge processes. As a consequence, the composite demonstrates excellent rate performance and cycling stability for both Li-ion and Na-ion storage. In particular, the F-G/Sn@C anode exhibits an impressive reversible capacity of 506mAh g−1 even after 500 cycles and a high-rate capacity of 270mAh g−1 even at 3200mAg−1 for Li-ion storage. Moreover, a reversible Na-ion storage capacity of 413 mAh g−1 with negligible fading is also achieved. The remarkable electrochemical performance, together with the facile synthetic approach for large scale production, enables such material as a highly attractive tin-based anode for next generation rechargeable batteries.
The thermodynamics and kinetics of the lithium insertion reaction into hollandite oxides BaMMn7O16 (M=Mg, Mn, Fe, Ni) have been studied. The electrochemical lithium insertion was achieved using the oxide as the cathode at current densities from 0.025 to 0.1 mA cm−2, using 1 M LiClO4 solution of PC and EC. The Ni compound inserts about three times more efficiently than the Mn compound. The changes of the partial molar enthalpy and the molar entropy as a function of the degree of insertion (x) were estimated from emf–temperature measurements in the range from 298 to 360 K. These thermodynamic parameters varied with the oxide composition and with the Li concentration in the oxide structure. The chemical diffusion coefficient for lithium D* in the hollandite and the electrical conductivity of the oxides were measured as a function of the lithium composition. Both parameters decrease with x, the largest variation being observed around x=1. The values of D*, measured at 298 K, followed the order: Ni>Fe>Mg=Mn. The hollandite oxides were characterized by X-ray diffraction analysis and magnetic susceptibility measurements as a function of temperature in the range 298–550 K which in turn allows postulation of each cationic distribution. BaNiMn7O16 inserts almost 6 mol of lithium ions per mole of the oxide.
Flexible and stretchable electronics, also known as e-skin, have been a technology to create diversified sensors and wearable devices. Implantable bioelectronics have recently been recognized as a promising research field to modulate biological signals and treat many diseases and pathological conditions. The marriage of two technologies gives us a new cutting-edge research area, i.e., implantable flexible electronics. While strain sensors, ECG sensors, pH sensors, temperature sensors and LED chips have been integrated together as a novel platform for measuring physiological signals, one of critical challenges for long-term use of such devices is a reliable power source with sound output power. To support operation of the implantable bioelectronics, triboelectric nanogenerators (TENGs) have recently been explored, as a promising technology to harvest energy, as the concept of scavenging human body energy into useful electrical power. In this work, we investigate stacked TENGs with output voltage of 160 Vp-p and a short circuit current of 6.7µA as a potential power source for neural stimulation using flexible and adjustable neural interfaces. To advance a generic design of flexible neural interfaces which is good at sciatic nerve recording and stimulation, we optimize a new flexible sling electrode and successfully achieve neural signal recording with different amplitudes and latencies. More importantly, successful selective stimulation achieved in this work proves that the flexible sling electrode is a good generic neural interface. We demonstrate direct stimulation of a sciatic nerve and a common peroneal nerve in rats by the TENGs connected with the suggested interface and a pair of Pt/Ir wires, respectively, while monitoring muscle signals. The muscle contraction can be controlled by the operation of the TENGs. This prove-concept result indicates that this technology could be the way of realizing battery-free wearable neuromodulators in the future.
Electric vehicles (EVs) are currently seen as an option for a more sustainable transportation sector, but it is not yet clear how to supply them with electricity whilst striving for low costs and low CO2 emissions. Renewable sources can supply electricity with low emissions, but their penetration rate is still insufficient to meet current demand, let alone the extra demand of EVs. A promising option is supply by Combined Heat and Power (CHP) plants with high combined efficiencies, but an in-depth evaluation of the benefits of combining of EVs and CHP plants is still missing. Therefore, this study evaluates the performance of four different types of CHP plants to power electric vehicles, as compared to use of electricity from the grid. The performance of CHP plants is simulated using detailed datasets of the composition of a future power system, the demand for household electricity and heat, and technical specifications of CHP plants and electric vehicles. We find that the lowest abatement costs of 60–190€/tCO2 are achieved with grid electricity based on a low-carbon electricity mix compared to a business-as-usual electricity mix with marginal emissions of 450–500gCO2/kWh. When electricity is supplied by CHP plants, emissions are −1000 to 400gCO2/kWh, and abatement costs are 165–940€/tCO2. We did not observe added benefits of joint implementation of CHP plants and EVs: the timing of CHP electricity supply and EV electricity demand did not match well, and abatement costs were not lowered.
A motor-imagery-based brain–computer interface (BCI) is a translator that converts the motor intention of the brain into a control command to control external machines without muscles. Numerous motor-imagery-based BCIs have been successfully proposed in previous studies. However, several electroencephalogram (EEG) channels are typically required for providing sufficient information to maintain a specific accuracy and bit rate, and the bulk volume of these EEG machines is also inconvenient. A wearable motor imagery-based BCI system was proposed and implemented in this study. A wearable mechanical design with novel active comb-shaped dry electrodes was developed to measure EEG signals without conductive gels at hair sites, which is easy and convenient for users wearing the EEG machine. In addition, a wireless EEG acquisition module was also designed to measure EEG signals, which provides a user with more freedom of motion. The proposed wearable motor-imagery-based BCI system was validated using an electrical specifications test and a hand motor imagery experiment. Experimental results showed that the proposed wearable motor-imagery-based BCI system provides favorable signal quality for measuring EEG signals and detecting motor imagery.
Mesocrystal MnO cubes consisted of nanocrystals (~16nm) with percolated nanopores (~10.5nm) and a porosity of 45% were synthesized through polyvinyl alcohol (PVA) assisted hydrothermal growth and homoepitaxial aggregation. The resulting MnO crystal makes up of appreciable amount of Mn3+, ~11.8%, ascribed to incomplete reduction during the hydrothermal growth, and the presence of such an appreciable amount of Mn3+ is thought to lead to the enhancement of Li ion diffusion coefficient from 6.96×10−14 cm2/s to 3.33×10−13 cm2/s. Carbon coating derived from polyvinyl alcohol and homoepitaxial connection of nanocrystals provides excellent charge and mass transfer pathways. Such mesocrystal MnO cubes enhanced the contact of electrolyte and electrode materials, at the same time the active nanocrystals with trivalent manganese ions and cationic vacancies would promote the conversion reaction for lithium-ion insertion and extraction, leading to a high capacity of 637mAh/g at 100mA/g in a relatively smaller voltage range of 0.05–2.50V, as compared with a voltage window of 0.01–3V used by other research groups. The high voltage (4V) Li-ion capacitor, a full cell with mesocrystal MnO cubes as anode and activated carbon as cathode, demonstrated excellent cycling performance with the degradation rate of 0.002% per cycle, and the achieved maximum energy in full capacitor reached 227Whkg−1 that calculated on the total weight of the active materials in both electrodes.
Passive acoustic telemetry was used to monitor the movements of cownose rays (Rhinoptera bonasus) within the Caloosahatchee River estuary in Southwest Florida. Twelve rays were tracked within the river between January 2004 and May 2005 for periods up to 234 days. Linear home range was calculated for all individuals and ranged between 0 and 18.4 km (daily) and 1 and 22.3 km (overall). Ray position within the river was compared to changing water quality parameters throughout the study. Although home range size did not increase with increasing salinity, individuals did occur farther upriver with decreasing flow rates and increasing salinity. There were no differences detected between day and night distribution patterns. Movement and presence patterns demonstrated significant use of the estuarine river over all months, indicating that cownose rays in southwest Florida may not undertake long seasonal migrations as established for other parts of their range.
In this review we try to shed a comprehensive understanding on the influence of the different parameters of the formulation of silicon-based composite electrode on its cyclability, i.e. the binder, the conductive additives, the current collector, the electrode porosity and solid loading, in view of a more rational assessment of the relevancy of these parameters for the battery technology. The reasons of the better efficiency of carboxymethyl cellulose and alternative new binders than PVdF are first addressed into details. The critical effects of the active mass loading and porosity on the cyclability are highlighted. Then the influence of the conductive additive type and current collector texture are discussed. Putting everything together shows that it is required to meticulously optimize all the different scales of the composite electrode to hopefully raise the performance of silicon-based electrode above that of graphite commercial ones.
Nucleation and growth mechanism of polypyrrole (PPy) films was investigated on vapor deposited gold/highly oriented pyrolytic graphite (Au/HOPG) after heat treatment by means of current–time transient (i–t) measurements and tapping mode atomic force microscopy. It was found that the nucleation and growth was a progressive 3-D before and after nuclei overlapping. However, the mechanism was 2-D instantaneous before nuclei overlapping and 3-D progressive after nuclei overlapping on a Au/HOPG substrate without heat treatment. The change in mechanism was due to lower surface defects on a heat-treated Au/HOPG substrate than on a bare Au/HOPG substrate. Images of PPy on a heat-treated Au/HOPG contained zig-zag and nodular structures.
Al2O3-modified Li(Ni1/3Co1/3Mn1/3)O2 is synthesized by a modified Al2O3 coating process. The Al2O3 coating is carried out on an intermediate, (Ni1/3Co1/3Mn1/3)(OH)2, rather than on Li(Ni1/3Co1/3Mn1/3)O2. As a comparison, Al2O3-coated Li(Ni1/3Co1/3Mn1/3)O2 also is prepared by traditional Al2O3 coating process. The effects of Al2O3 coating and Al2O3 modification on structure and electrochemical performance are investigated and compared. Electrochemical tests indicate that cycle performance and rate capability of Li(Ni1/3Co1/3Mn1/3)O2 are enhanced by Al2O3 modification without capacity loss. Al2O3 coating can also enhance the cycle performance but cause evident capacity loss and decline of rate capability. The effect of Al2O3 coating and Al2O3 modification on kinetics of lithium-ion transfer reaction at the interface of electrode/electrolyte is investigated via electrochemical impedance spectra (EIS). The result support that the Al2O3 modification increase Li+ diffused coefficient and decrease the activation energy of Li+ transfer reaction but the traditional Al2O3 coating lead to depression of Li+ diffused coefficient and increase of activation energy.
In neurons, DNA is prone to free radical damage, although repair mechanisms preserve the genomic integrity. However, activation of the DNA repair system, poly(ADP-ribose) polymerase (PARP-1), is thought to cause neuronal death through NAD+ depletion and mitochondrial membrane potential (Δψm) depolarization. Here, we show that abolishing PARP-1 activity in primary cortical neurons can either enhance or prevent apoptotic death, depending on the intensity of an oxidative stress. Only in severe oxidative stress does PARP-1 activation result in NAD+ and ATP depletion and neuronal death. To investigate the role of PARP-1 in an endogenous model of oxidative stress, we used an RNA interference (RNAi) strategy to specifically knock down glutamate-cysteine ligase (GCL), the rate-limiting enzyme of glutathione biosynthesis. GCL RNAi spontaneously elicited a mild type of oxidative stress that was enough to stimulate PARP-1 in a Ca2+-calmodulin kinase II-dependent manner. GCL RNAi-mediated PARP-1 activation facilitated DNA repair, although neurons underwent Δψm loss followed by some apoptotic death. PARP-1 inhibition did not prevent Δψm loss, but enhanced the vulnerability of neurons to apoptosis upon GCL silencing. Conversely, mild expression of PARP-1 partially prevented to GCL RNAi-dependent apoptosis. Thus, in the mild progressive damage likely occur in neurodegenerative diseases, PARP-1 activation plays a neuroprotective role that should be taken into account when considering therapeutic strategies.
CoS2–graphene composites (CoS2–Gs) were synthesized via a facile hydrothermal reaction between cobalt ions and thiourea in the presence of graphene oxide (GO). By this means, the size and distribution of the formed CoS2 nanoparticles onto flexible graphene sheet could be effectively controlled, which is crucial for achieving of high electrocatalytic activity on I3 − reduction. Mainly due to the homogeneous single-layer immobilization of CoS2 nanoparticles onto graphene sheet with high density, CoS2–G50, which was synthesized by incorporation of 50mg GO, exhibited the highest catalytic activity and the lowest electrolyte diffusion resistance. As a result, the dye sensitized solar cell (DSSC) using CoS2–G50 as counter electrode (CE) offered a power conversion efficiency (PCE) of 6.55%, which is much higher than that of cell using sole CoS2 or graphene CE. The PCE also outperformed that of Pt CE based cell (6.20%), manifesting the application potential of CoS2–G as low cost non-Pt CE materials for DSSC.
Although there is a rich body of research available regarding the effect of acute and chronic khat dosing in animal models, research on the behavioral and cognitive effects of khat in human subjects is not extensive and several of the available studies have been done only in the context of observational and single-case studies. In light of the absence of a substantial literature on the neurobehavioral deficits associated with khat use and to provide a context that could be used to identify themes for future research we review previous research that has focused on other stimulant drugs. This review highlights multiple areas of neurocognitive deficit that have been identified in previous studies of individuals who have been chronic users of stimulants, such as amphetamines and methamphetamines. The review highlights a substantial body of evidence demonstrating a wide range of learning and memory impairments including deficits that persist during abstinence from active drug use. This review does not imply a similar khat effect, but due to some similarities pharmacologically between the active components of khat (cathinone and cathine) and amphetamines, future studies examining these same domains of cognitive functioning in chronic khat users and abstinent khat users appears to be warranted, if possible using some of the same or similar laboratory measures.
A LiFePO4/C composite was successfully prepared by a polymer-pyrolysis–reduction method, using FePO4·2H2O and lithium polyacrylate (PAALi) as raw materials. The structure of the LiFePO4/C composites was investigated by X-ray diffraction (XRD). The micromorphology of the precursor and LiFePO4/C powders was observed using scanning electron microscopy (SEM), and the in situ coating of carbon on the particles was observed by transmission electron microscopy (TEM). Furthermore, the electrochemical properties were evaluated by cyclic voltammograms (CVs), electrochemical impedance spectra (EIS) and constant current charge/discharge cycling tests. The results showed that the sample synthesized at 700°C had the best electrochemical performance, exhibiting initial discharge capacities of 157, 139 and 109mAhg−1 at rates of 0.1, 1 and 5C, respectively. Moreover, the sample presented excellent capacity retention as there was no significant capacity fade after 50 cycles.
Low temperature syntheses of LiCoO2 cathode materials for Li-secondary battery applications were studied in aqueous solutions by hydrothermal and reflux reactions. By controlling the oxidation potential of the reaction environments, we could synthesize phase pure LiCoO2 directly from Co(OH)2 at as low as 130°C, contrary to the reported hydrothermal reactions at 200–220°C starting with CoOOH. Having high pH over 15 and an O2 flow induced the oxidation reaction of the divalent cobalt in Co(OH)2. The products so obtained have well-crystallized high temperature form of LiCoO2 with the layered structure as proved by powder X-ray diffraction (XRD) and the Raman spectroscopy data. The particles have a uniform size distribution around 100nm with well-developed crystallite morphology.