batterydata/paper-abstracts huggingface dataset:
In situ transmission FTIR spectra are measured during the electrochemical insertion of lithium into phospho-olivine FePO4. The spectroelectrochemical cell consists of a composite FePO4 cathode, a lithium metal anode, and an electrolyte of 1M LiPF6 in a 1:1 mixture of ethylene carbonate and diethyl carbonate (EC–DEC). Bands belonging to the electrolyte and cathode are identified in the infrared spectra of the in situ cells. The antisymmetric PO4 3− bending vibrations (ν4) are used to monitor Li+ insertion into FePO4. Discharging produces spectral changes that are consistent with the formation of phospho-olivine LiFePO4, yet the electrolyte bands are not affected by the discharging process. The in situ infrared experiments confirm the two-phase mechanism for lithium insertion into FePO4. Moreover, the experiments demonstrate the ability to collect in situ transmission FTIR spectra of functioning electrode materials in lithium batteries. Unfortunately, lithium plating occurs on the optical window when the Li//FePO4 half-cells are charged. The use of an intercalation anode such as graphite could alleviate this problem; however, this avenue of research is not explored in this study.
Background and purpose Many patients with Parkinson's disease (PD) experience sleep-related symptoms. Studies in other populations indicate that melatonin can increase sleep efficiency, decrease nighttime activity, and shorten sleep latency, but there has been little research on the use of melatonin in PD. The purpose of this study was to compare the effects of two doses of melatonin to placebo on sleep, daytime sleepiness, and level of function in patients with PD who complained of sleep disturbances. Patients and methods A multi-site double-blind placebo-controlled cross-over trial was employed; 40 subjects completed the 10-week protocol. There was a 2-week screening period, 2-week treatment periods, and 1-week washouts between treatments. Nocturnal sleep was assessed by actigraphy and diaries, whereas daytime sleepiness and function were assessed by the Epworth Sleepiness Scale (ESS), Stanford Sleepiness Scale (SSS), and General Sleep Disturbance Scale (GSDS). Results Repeated measures analysis of variance revealed a significant improvement in total nighttime sleep time during the 50mg melatonin treatment compared to placebo. There was significant improvement in subjective sleep disturbance, sleep quantity, and daytime sleepiness during the 5mg melatonin treatment compared to placebo as assessed by the GSDS. Conclusions Although we found a statistically significant improvement in actigraphically measured total sleep time on 50mg melatonin compared to 5mg or placebo, this small improvement (10min) may not be clinically significant. However, the significant improvement found in subjective sleep disturbance suggests that these modest effects may be clinically relevant in this patient population.
Audit offices in the US exhibit a wide variation in the number of industries they service. Strategic management theory suggests that diversification can affect the quality of output, depending on the nature and circumstances of diversification. This paper examines the effect of diversification at the audit office level on audit quality. Five proxies of audit quality are examined, mainly, absolute discretionary accruals, propensity to meet-or-beat earnings expectations by a cent, propensity to restate financial statements, propensity to receive a comment letter after an SEC review and propensity to issue a going concern opinion. Results suggest that diversification has detrimental effects on audit quality. On the other hand, when the diversification is part of the audit firm level strategy, the detrimental effects on audit quality are dampened. Moreover, when the diversification at the office level is part of a revenue expansion strategy, the audit quality is adversely affected. However, there is no detrimental effect on the audit quality when revenue expansion is not the objective. Also, diversification across dissimilar industries leads to more adverse effect on audit quality than diversification to similar industries. Results also suggest that when the audit office is located in a market with more (less) diversified client base, the adverse effects of diversification on audit quality are weaker (stronger). Finally, the offices of big-4 audit firms handle diversification better with less adverse effect on audit quality. The findings are important since they identify additional factors that explain audit quality at the audit office level.
In this paper, a novel impedance spectroscopy was used to describe the thermal behaviors of Ni-MH batteries. The impedance functions were derived similarly to electric impedance functions. The square of current was treated as a current equivalent and heat-flow as a voltage equivalent. The impedance spectra of batteries during charge showed that the combination of hydrogen and oxygen increased rapidly when charge rate was higher than 0.5C. Thermal runaway might happen when battery was charged at temperature above 348K even at a low charge rate. The cycling test showed that the charge efficiency of battery was the highest after cycling at high-rate for 10–100 cycles and decreased after more cycles. Different batteries showed different thermal behaviors which may be caused by the different structures of batteries.
Amorphous MgNi material has been synthesized by mechanical alloying and sieved into three particle size fractions: >75, 20–75, and <20μm. The influence of the MgNi particle size on its electrochemical behavior as negative electrode for Ni–metal hydride (MH) batteries has been investigated. The initial discharge capacity is higher as the MgNi particle size increases, i.e. the initial discharge capacity of particles larger than 75μm is 439mAh/g compared to 396 and 328mAh/g for 20–75 and <20μm particles, respectively. In addition, the cycle life of the MgNi electrode is improved by increasing the particle size. That is, the >75μm particles electrode retains 41% of its initial capacity after 15 cycles compared to 35 and 23% for 20–75μm and <20μm particles electrodes, respectively. The rate dischargeability is also improved by increasing the MgNi particle size. For example, at 400mA/g, the >75μm particles electrode delivers 33% of its capacity measured at 20mA/g compared to 25 and 19% for 20–75μm and <20μm powders, respectively. These results can be explained by the lower specific surface area of the electrode constituted of large particles which limits the formation of Mg(OH)2 resulting from the MgNi oxidation by the electrolyte. Moreover, on the basis of the evolution of the cycling discharge capacities with increasing charge input for the different powder fractions, it appears that the electrode resistance to pulverization is improved by increasing the MgNi particle size.
Although the outcome of total knee replacement (TKR) is favorable, surgery alone fails to resolve the functional limitations and physical inactivity that existed prior to surgery. Exercise is likely the only intervention capable of improving these persistent limitations, but exercises have to be performed with intensity sufficient to promote significant changes, at levels that cannot be tolerated until later stages post TKR. The current evidence is limited regarding the effectiveness of exercise at a later stage post TKR. To that end, this study aims to compare the outcomes of physical function and physical activity between 3 treatment groups: clinic-based individual outpatient rehabilitative exercise during 12 weeks, community-based group exercise classes during 12 weeks, and usual medical care (wait-listed control group). The secondary aim is to identify baseline predictors of functional recovery for the exercise groups.
Polymer electrolytes consisting of poly(ethylene oxide) (PEO) and lithium salts, such as LiCF3SO3 and LiBF4 are prepared by the ball-milling method. This is performed at various times (2, 4, 8, 12h) with ball:sample ratio of 400:1. The electrochemical and thermal characteristics of the electrolytes are evaluated. The structure and morphology of PEO–LiX polymer electrolyte is changed to amorphous and smaller spherulite texture by ball milling. The ionic conductivity of the PEO–LiX polymer electrolytes increases by about one order of magnitude than that of electrolytes prepared without ball milling. Also, the ball milled electrolytes have remarkably higher ionic conductivity at low temperature. Maximum ionic conductivity is found for the PEO–LiX prepared by ball milling for 12h, viz. 2.52×10−4 Scm−1 for LiCF3SO3 and 4.99×10−4 Scm−1 for LiBF4 at 90°C. The first discharge capacity of Li/S cells increases with increasing ball milling time. (PEO)10LiCF3SO3 polymer electrolyte prepared by ball milling show the typical two plateau discharge curves in a Li/S battery. The upper voltage plateau for the polymer electrolyte containing LiBF4 differs markedly from the typical shape.
Lithiation of a crystalline silicon anode proceeds by the movement of an atomically sharp reaction front that separates a pristine crystalline phase and a fully-lithiated amorphous phase. The velocity of the reaction front is limited rather by the reaction rate at the lithiation front than by the diffusivity of lithium ions in the amorphous lithiated phase. Experiments on solid nanoparticle/nanowire silicon anodes show an initial rapid advancing of reaction front at the initial stage of lithiation, followed by an apparent slowing or even halting of the reaction front propagation. Lithiation-induced stresses during lithiation are attributed to alter the driving force of lithiation and thus result in the observed slowing of reaction front. Recent experiments on lithiation of hollow silicon nanowires reveals similar slowing of reaction front, however, quantitative study of the effect of lithiation-associated stress on the driving force of lithiation still lacks so far. Here, through chemo-mechanical modeling and theoretical formulation, we present a comprehensive study on lithiation-induced stress field and its contribution to the driving force of lithiation reaction in hollow silicon nanowire anodes. We show that hollow silicon nano-anodes could be fully lithiated with lower stress-induced energy barrier than solid silicon nano-anodes. As a result, it is expected that the hollow nanowires and nanoparticles may serve as an optimal structural design for high-performance anodes of lithium-ion batteries. Results from the present study shed light on a number of open questions of lithiation kinetics of silicon-based anodes in recent literature and offer insight on developing silicon-based anodes with high charging capacity and high charging rate.
Organolead halide perovskite solar absorbers demonstrate high photovoltaic efficiencies but they are notorious for their intolerance to water. Now, methylammonium lead iodide perovskites are used to harvest solar energy — in water — via photocatalytic generation of hydrogen from solutions of hydriodic acid.
This paper addresses the problem of secure data transmission and balanced energy consumption in an unattended wireless sensor network (UWSN) comprising of multiple static source nodes and a mobile sink in the presence of adversaries. The proposed system comprises of three phases: the identification of data collection points (convex nodes), path planning by the mobile sink, and secure data transmission. An energy-aware convex hull algorithm is used for the identification of data collection points for data transmission to the mobile sink. Data transmission from sensor nodes to the nearest data collection point is performed using multihop communication and from sensor nodes to the mobile sink in a single hop. Data are securely transmitted through an elliptic curve cryptography based ElGamal scheme for message authentication. A data packet is associated with a digital signature. The variation in a digital signature and threshold energy obtained using support vector machine is used to determine the presence of malicious nodes in the network. The performance of the proposed system is evaluated using Cooja simulator by Contiki for various node counts under a static sink and mobile sink, with different threat scenarios. The results indicate that the proposed system is resilient against threats and provides satisfactory performance
Novel hierarchically porous titanium-metal organic frameworks/nitrogen-doped graphene (Ti-MOFs/NG) nanocomposite derived from titanium-metal organic frameworks (Ti-MOFs) and the nitrogen-doped graphene (NG) has been originally synthesized successfully. Notably, the Ti-MOFs/NG nanocomposite has been for the first time investigated in detail, as oxygen reduction reaction (ORR) catalyst of cathodic materials for fuel cells. The results show that the Ti-MOFs/NG nanocomposite possesses excellent ORR performances, whether in alkaline or acidic medium, due to existences of the Ti3N2-x, C2O7Ti2.3, H2Ti5O11, Ti and TiO active ORR segments. Specifically, the onset potential (E0) and the Tafel slope value of the Ti-MOFs/NG nanocomposite are 1.14 V and 17.84 mV dec−1 in 0.1 M HClO4, respectively. Similarly, high ORR efficiency of the Ti-MOFs/NG nanocomposite also exhibit in alkaline medium. The relative current density can still keep 99.88% of the original value after 10800 s measurements in 0.1 M KOH. Additionally, small electrochemical impedance and excellent tolerance toward fuel molecules have been exhibited in both electrolytes. These ORR properties are superior to those of most of previously reported materials derived from other MOFs, in both alkaline and acidic media. Thus, the Ti-MOFs/NG nanocomposite is as a novel promising candidate for ORR catalyst to solve the main problems of sluggish reaction kinetics of the ORR, high cost of precious metal catalysts and low durability of the traditional catalysts, applied to fuel cells, metal-air batteries and further to water splitting in energy conversion and storage devices.
Does childrearing affect the biological functioning of parents? To address this question, we analyze cross-sectional survey and biomarker data from Vanderbilt University’s Nashville Stress and Health Study, a probability sample of non-Hispanic White and Black working-age adults from Davidson County, Tennessee (2011–2014; n = 1252). Multivariable regression analyses reveal a linear dose–response relationship between the number of children living in a respondent’s home and (a) increased allostatic load, and (b) decreased leukocyte telomere length. We found no differences in biological functioning between childless respondents and empty-nest parents. These findings also withstood controls for a battery of socioeconomic factors. The implications of these findings and suggestions for future research are discussed.
Three-phase gas-diffusion oxygen electrodes for metal air battery were prepared and characterized. Nano-structured γ-MnO2 catalysts were synthesized by solid state redox reaction of two compounds, Mn(CH3COO)2·4H2O and C2H2O4·2H2O. Their crystal phase, morphologies and particle size were characterized by XRD, TEM, respectively. The electrochemical property of three-phase gas-diffusion oxygen electrodes composed of nano-structured γ-MnO2 catalysts for oxygen reduction was examined by using the linear polarization method in a neutral solution. Besides, the surface morphologies of the catalytic layer of three-phase gas-diffusion oxygen electrodes were also investigated by SEM. Experimental results revealed that these kinds of three-phase gas-diffusion oxygen electrodes have excellent electrochemical performance. The optimal proportion of nano-structured γ-MnO2 catalysts in the catalytic layer was 60wt.%. Three-phase gas-diffusion oxygen electrodes composed with nano-structured γ-MnO2 catalysts appear to be a highly possible candidate for applications in neutral solution metal air battery.
The use of agricultural and food processing waste is an important source of biomass fuel for energy generation in rural and remote locations. In particular, gasification of cashew nut shell has a high potential for clean electricity generation due to its relative high energy content. In this study, the techno-economic assessment of a solar photovoltaic-biomass gasification hybrid system is carried out for a case study in Nampula, Mozambique. Model results and sensitivity analysis show that this system is able to achieve competitive levelised cost of electricity when compared with diesel generators.
Porous Co(OH)2/Ni composite nanoflake array is prepared by combing hydrothermal synthesis and electrodeposition methods. The as-prepared Co(OH)2/Ni composite nanoflake array exhibits a highly porous array structure composed of free-standing nanoflakes with thicknesses of 35–40nm. The pseudocapacitive behavior of the Co(OH)2/Ni composite nanoflake array is investigated by cyclic voltammograms (CV) and galvanostatic charge–discharge tests in 2M KOH. As cathode material for supercapacitor, the porous Co(OH)2/Ni composite nanoflake array exhibits weaker polarization, higher electrochemical activity and better cycling performance as compared to the unmodified Co(OH)2 nanoflake array. The Co(OH)2/Ni composite nanoflake array shows specific capacitances of 1310Fg−1 at 1Ag−1 and 1148Fg−1 at 40Ag−1, much higher than those of the unmodified Co(OH)2 nanoflake array (1017Fg−1 at 1Ag−1 and 775Fg−1 at 40Ag−1). The enhancement of supercapacitor properties is due to the introduction Ni in the composite array, which improves the electric conductivity of the film electrode with fast reaction kinetics.
Ambient temperature sodium-ion batteries are emerging as a new chemistry platform for energy storage technologies. Anodes that consist of carbon have been used for this application due to their highly stable and reversible Na cycling nature. In the search of new carbon materials with various microstructure morphologies, we have synthesized spherical carbon particles via an autogenic process. 23Na MAS solid-state NMR characterization method as a function of the state of charge of carbon was used to determine that these spherical carbon anodes show pure, reversible Na intercalation into graphene regions: these materials are devoid of nanocavity or nanopore filling of Na. This feature and the spherical morphology create low reactivity behavior with the electrolyte which assists in the material's highly reversible (de)sodiation. Specific capacity is 40mAhg−1 at a high-rate of 10C (1.5Ag−1) thus demonstrating that the graphene element in hard carbons contributes largely to the rate capability.
Gel polymer electrolyte films comprised of 50% epoxidised natural rubber polymer host, lithium triflate salt (LiCF3SO3), and ethylene carbonate (EC) or propylene carbonate (PC) plasticizer are prepared using the solution-casting technique. AC impedance studies show that the electrical conductivity of the electrolytes is dependent on both the salt and plasticizer concentrations. The highest room temperature conductivity of 4.92×10−4 Scm−1 is achieved when 10wt.% propylene carbonate is introduced into the system containing 1.0g 50% epoxidised natural rubber polymer doped with 35wt.% LiCF3SO3. Conductivity studies of these polymer electrolytes are carried out at various temperatures and are found to obey the Vogel–Tamman–Fulcher (VTF) rule. The highest conducting plasticized sample is used as a gelled electrolyte for lithium–air cells.
The purpose of this paper is to review the current status of the recycling technologies of spent lithium-ion secondary batteries. It introduced the structure and components of the lithium-ion secondary batteries, summarized all kinds of single recycling processes from spent lithium-ion secondary batteries and presented some examples of typical combined recycling processes. Also, the problems and prospect of the studies of their recycling technologies have been put forward.
A 3D structured NiCo2O4@Co3O4 hybrid was prepared by a two-step hydrothermal approach and subsequently employed as a highly efficient catalyst in oxygen reduction reactions (ORRs)/oxygen evolution reactions (OERs) and from a Li–O2 battery perspective. The Co-NC possesses interconnected NiCo2O4 nanorods grown over a Co3O4 nanosheet structure, which facilitates charge transfer and enhances the electrical conductivity. Moreover, the 3D structured hybrids are directly used as a cathode catalyst for the Li–O2 system and displayed a maximum in-depth-specific discharge capacity of 4386mAhg−1. In addition, significantly improved and stable cycling performance up to 60 cycles is observed compared with Co3O4 nanosheets at the limited capacity range of 500mAhg−1. The excellent electrochemical performance of the NiCo2O4@Co3O4 hybrid is mainly associated with the oxygen-deficient 3D architecture providing more catalytic active sites and can accommodate more discharge products. Further, ORR/OER activities of NiCo2O4@Co3O4 hybrid in aqueous media are also evaluated in 0.1M KOH solution using the rotating ring disk electrode technique. For instance, the OER activity of NiCo2O4@Co3O4 hybrid (apex current is 4.18mAcm−2) is an approximately 2.25 times higher than that of commercial RuO2 catalyst (1.84mAcm−2). Since the catalytic activity in aqueous and organic medium is not necessarily the same, but of NiCo2O4@Co3O4 hybrid exhibiting excellent ORR/OER characteristics in both cases is worth mentioning.
A pressing question in military medical research is the nature and degree of effects on the human brain from occupational repeated exposure to low-level explosive blast, but reliable and effective means to objectively measure such effects remain elusive. In survey results, headache, difficulty sleeping, irritability, cognitive impairment, and a variety of other symptoms consistent with post-concussive syndrome have been reported by those exposed to blast and there was positive correlation between degree of blast exposure and degree of symptomology, but an important goal is to obtain more objective evidence of an effect than self-report alone. This review reflects recent efforts to measure and evaluate such hypothesized effects and current recommendations for ongoing study. Optimal measures are likely those with sensitivity and specificity to systemic effects in mild neurotrauma, that have minimal to no volitional component, and that can be sampled relatively quickly with minimal intrusion in prospective, observational field studies during routine training with explosives. An understanding of an association between parameters of exposure to repeated low-level blast and negative neurologic effects would support the evaluation of clinical implications and development of protective equipment and surveillance protocols where warranted. At present, low-level blast exposure surveillance measurements do not exist as a systematic record for any professional community.
Artificial insemination is not as widely used in horses as in other domestic species, such as dairy cattle and pigs, partly because of the wide variation in sperm quality between stallion ejaculates and partly due to decreased fertility following the use of cooled transported spermatozoa. Furthermore, predictive tests for sperm fertilising ability are lacking. The objective of the present study was to assess sperm morphology and chromatin integrity in ejaculates obtained from 11 warmblood breeding stallions in Sweden, and to evaluate the relationship of these parameters to pregnancy rates to investigate the possibility of using these tests predictively.