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Since the gel polymer electrolytes based on polyacrylonitrile (PAN) host have not been sufficient to fulfil the requirements as a separator of current lithium polymer battery, a new polymer host copolymerized with PAN, polyacrylonitrile-co-bis[2-(2-methoxyethoxy)ethyl]itaconate (abbreviated as PANI), was synthesized in expectation of enhanced trapping ability of liquid electrolytes. Electrical, electrochemical, thermal and mechanical studies have been carried out on PAN and PANI blended gel polymer electrolytes, complexed with ethylene carbonate (EC) and γ-butyrolactone (BL) containing LiClO4 salt. The addition of PANI as a host polymer in the PAN-based gel polymer electrolytes has beneficial effects such as higher ionic conductivity, better thermal and electrochemical stabilities and enhanced ability of trapping organic solvent, possibly due to ion chelating ability of itaconate unit, though it shows less mechanical rigidity caused by amorphization of the PAN matrix.
Tris(trimethylsilyl)borate (TMSB) is used as an electrolyte additive for high voltage lithium-rich oxide cathode of lithium ion battery. The interfacial natures of Li[Li0.2Mn0.54Ni0.13Co0.13]O2/carbonate-based electrolyte are investigated with a combination of electrochemical measurements and physical characterizations. Charge/discharge tests show that the cyclic performance of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 in a mixed carbonate electrolyte is significantly improved by using TMSB. After 200 cycles between 2 V and 4.8 V (vs. Li/Li+) at 0.5 C rate, the capacity retention of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is only 19% in the blank electrolyte, while it is improved to 74% when 0.5% TMSB is applied. The results from physical characterizations demonstrate that this excellent cyclic performance is attributed to the improved interfacial stability of Li[Li0.2Mn0.54Ni0.13Co0.13]O2/electrolyte due to the thin and protective film generated by TMSB.
Rational and precise control of the structure and dimension of electrode materials is an efficient way to improve their electrochemical performance. In this work, solvothermal or co-precipitation method is used to synthesize lithium-rich layered oxide materials of Li1.2Mn0.56Co0.12Ni0.12O2 (LLO) with various morphologies and structures, including microspheres, microrods, nanoplates, and irregular nanoparticles. These materials exhibit strong structure-dependent electrochemical properties. The porous hierarchical structured LLO microrods exhibit the best performance, delivering a discharge capacity of 264.6mAhg−1 at 0.5C with over 91% retention after 100 cycles. At a high rate of 5C, a high discharge capacity of 173.6mAhg−1 can be achieved. This work reveals the relationship between the morphologies and electrochemical properties of LLO cathode materials, and provides a feasible approach to fabricating robust and high-performance electrode materials for lithium-ion batteries.
A stable magnesium battery has been developed based on a magnesium anode, a poly(dioxyethane thiophene) (PEDOT) cathode and a near-saturated aqueous solution of LiCl, MgCl2, or mixture of these salts at pH of 11. This combination leads to a low water activity in the electrolyte, which thus suppresses the hydrogen evolution reaction on Mg, as well as producing a stable oxy-hydroxide film which protects the metal surface from freely corroding. The conducting polymer cathode is reduced somewhat during the discharge process, however, appears to be readily re-oxidised (as determined from the resistance) by the oxygen present in the cell. The cell is therefore primarily a Mg/O2 battery, however, the PEDOT appears to enhance the performance, in particular the discharge voltage.
The concept that blood cells arising from hematopoietic stem cells (HSC) can be subdivided into two major lineages, a myelo-erythroid and a lymphoid lineage, has long persisted. Indeed, it has become almost axiomatic that the first branch point from the HSC produces two progenitors, one for myelo-erythroid cells and the other for lymphoid cells. However, recent studies have provided a battery of findings that cannot be explained by this classical model. We will outline how this classical model arose before describing how we came to propose an alternative ‘myeloid-based model’, in which myeloid potential is retained in erythroid, T, and B cell branches even after these lineages have segregated from each other.
The rate of many chemical and energy transformation processes depends on the kinetics of charge and mass transfer in porous electrodes, but rational design of efficient nanostructured electrodes is hindered by an inability to quantify effects of micro/nano-structures of real devices. Here we report a framework for detailed simulations conformal to 3D micro/nano-scale reconstructions of porous structures, obtained from phase-sensitive x-ray nanotomography, using COMSOL and iso2mesh packages coordinated with custom code for automated feature recognition, meshing, refinement, equation assignment, and solution. This computational framework is illustrated in visualizing 3D surface activity of an operating solid oxide fuel cell (SOFC) electrode under low and high bias along two important transport pathways (bulk and surface), showing the effect of local nanostructured morphology on global electrochemical response and demonstrating cathodic activation of bulk La1−x Sr x MnO3±δ (LSM). The methodology is flexible with possibilities for superimposition of mechanical, thermal, and other processes and for incorporation of inputs from multi-scale calculations. It has potential to serve as a platform for rational design of complex nanostructured hetero-foam devices with desired functionalities.
Durability testing of solid oxide cell electrodes in reversing-current and constant-current operation modes is presented. (La0.8Sr0.2)0.98MnO3−δ–Zr0.84Y0.16O2−γ (LSM–YSZ) symmetric cells were tested at 800 °C in air with current densities of 0.5 and 1.5 A cm−2, with current cycle periods of 1 and 12 h. A continuous increase in both ohmic and polarization resistance was observed, via Electrochemical Impedance Spectroscopy (EIS), for cells tested with a reversing current of 1.5 A cm−2, whereas cells tested at 0.5 A cm−2 showed no measurable resistance increase. The resistance degradation was explained by delamination in the electrode, observed by post-test Scanning Electron Microscopy (SEM), near the interface with the electrolyte for the 1.5 A cm−2 cells, but not for those tested at 0.5 A cm−2. Current cycle period also impacted the degradation observed at 1.5 A cm−2: both the rate of resistance increase and the extent of post-test delamination decreased on going from constant current mode to a 12 h period to a 1 h period. The results indicate that lower current densities and reversing-current operation are desirable to maximize the lifetime of solid oxide cells.
Previous work has shown that in vitro thymulin treatments have the ability to enhance natural killer (NK) cell cytotoxicity. The purpose of the experiments presented here was to examine the in vivo effects of thymulin on avian NK cell activity in response to a viral infection. Five and a half-week-old K-strain chickens infected with avian infectious bronchitis virus (IBV) served as the model for these experiments. Daily thymulin injections began at varying time points prior to or post-infection. The controls received daily injections of the ZnCl2-containing carboxymethyl-cellulose (CMC) diluent. A 51Cr-cytolytic release assay was used to determine the activity of the NK cells harvested via lung lavage from the respiratory tracts of infected chickens. The results of these experiments showed that in vivo thymulin treatments enhance NK cytotoxicity. The greatest enhancement of NK cytotoxicity was observed at 10 days post-infection in those chickens that began receiving thymulin after infection. These results suggest that thymulin may not only have a role in enhancing immunosurveillance but also in enhancing the response of the innate immune system following infection. Dose–response experiments found that the 50 ng/100 g body weight (Bwt) dose significantly depressed the cytolytic activity of the NK cells in comparison to either the 10 ng/100 g Bwt dose or the control.
The health and social care sector (HCS) is currently facing multiple challenges across Europe: against the background of ageing societies, more people are in need of care. Simultaneously, several countries report a lack of skilled personnel. Due to its structural characteristics, including a high share of part-time workers, an ageing workforce, and challenging working conditions, the HCS requires measures and strategies to deal with these challenges.
Objectives Patients' ideas about the nature, cause, and treatment of their illnesses are part of the complex process of coping with illness. To date, limited research on subjective theories of illness in patients with irritable bowel syndrome (IBS) has been performed. The aim of the study was to investigate patients' subjective theories of illness and how these are related to clinical and psychological outcome criteria, in particular IBS symptom severity and quality of life. Methods Eighty-eight patients with IBS, as defined by Rome III criteria, were administered a battery of questionnaires to collect the following data: sociodemographic variables, subjective theories of illness (Subjektive Krankheitstheorien, Cause Questionnaire), anxiety (Hospital Anxiety and Depression Scale), depression (Beck Depression Inventory), quality of life (SF-12), and IBS symptoms (Questionnaire for Gastrointestinal Symptoms). Results Almost all patients reported theories of illness reflecting their subjective causal assumptions. The most frequently mentioned causal factors were physical illness, intrapsychic factors, and stress. Patients with mainly somatic attributions had higher IBS symptoms scores (P<.05) and reduced physical quality of life. Intrapsychic attributions were associated with reduced mental quality of life and enhanced physical quality of life (P<.01). All correlations were independent of gender, age, and irritable bowel subgroups. Conclusions Subjective theories of illness can have significant implications for IBS symptom severity, as well as for physical and mental quality of life.
International research has demonstrated that lesbian, gay, bisexual and transgender (LGBT) youth have elevated rates of suicide and self-harm. What is missing from the evidence base, however, is qualitative research investigating LGBT youth perspectives. This is a sensitive subject area presenting ethical, methodological and epistemological challenges, especially in relation to over-sampling the ‘visible’ sections of a hidden population, retrospective reporting, and capturing complex emotions. We report on our use of qualitative online methodology to examine Internet forums where LGBT youth discuss self-harming. We found that this methodology can address some research dilemmas by generating: (a) diverse samples in terms of sexuality and gender identities; (b) a different type of data, immediate and unmediated by researchers; and (c) complex psychosocial emotional data. We argue that this online data can enhance our understanding of the links among hard-to-reach youth, suicide, self-harm, sexuality and gender, which is crucial to developing effective and appropriate suicide prevention strategies and mental health policies.
Objective To investigate the maturation of long-latency auditory evoked potentials (LLAEP) from 6 to 48months in infants with a family history of language impairment (FH+) and control infants (FH−). Methods LLAEPs of seventeen FH+ infants were compared to 28 FH− infants at 6, 9, 12, 16, 24, 36 and 48months. Participants received a passive oddball paradigm using fast- and slow-rate non-linguistic auditory stimuli and at 36 and 48months completed a battery of standardized language and cognitive tests. Results Overall, the morphology of LLAEP responses differed for fast- versus slow-rate stimuli. Significant age-related changes in latency and amplitude were observed. Group differences, favoring FH− infants, in the rate of maturation of LLAEPs were found. Responses to fast-rate stimuli predicted language abilities at 36 and 48months of age. Conclusions The development of LLAEP in FH+ children is modulated by differences in the rate of maturation as well as variations in temporal processing abilities. Significance These findings provide evidence for the role of non-linguistic auditory processes in early language development and illustrate the utility of using a perceptual-processing skills model to further our understanding of the precursors of language development and impairment.
There is renewed interest in blood product use for resuscitation stimulated by recent military experience and growing recognition of the limitations of large-volume crystalloid resuscitation.
Previous studies report that acquired prosopagnosia is frequently associated with topographic disorientation. Whether this is associated with a specific anatomic subtype of prosopagnosia, how frequently it is seen with the developmental variant, and what specific topographic function is impaired to account for this problem are not known. We studied ten subjects with acquired prosopagnosia from either occipitotemporal or anterior temporal (AT) lesions and seven with developmental prosopagnosia. Subjects were given a battery of topographic tests, including house and scene recognition, the road map test, a test of cognitive map formation, and a standardized self-report questionnaire. House and/or scene recognition were frequently impaired after either occipitotemporal or AT lesions in acquired prosopagnosia. Subjects with occipitotemporal lesions were also impaired in cognitive map formation: an overlap analysis identified right fusiform and parahippocampal gyri as a likely correlate. Only one subject with acquired prosopagnosia had mild difficulty with directional orientation on the road map test. Only one subject with developmental prosopagnosia had difficulty with cognitive map formation, and none were impaired on the other tests. Scores for house and scene recognition correlated most strongly with the results of the questionnaire. We conclude that topographic disorientation in acquired prosopagnosia reflects impaired place recognition, with a contribution from poor cognitive map formation when there is occipitotemporal damage. Topographic impairments are less frequent in developmental prosopagnosia.
In this study, a new parameter having influence on the TiO2 nanotubes formation process is reported. Except of previously mentioned and well-known anodizing parameters such as voltage, time of anodizing, type of electrolyte, temperature, etc., samples’ configuration in the electrochemical cell represents an important factor in the anodizing procedure. The electrochemical anodization is a group of interconnected processes and factors, each one of them having its specific weight on the final result. It was observed that the very short distance in between two titanium plates connected to the anodic terminal of the electrochemical cell is the decisive factor for creating superimposed TiO2 nanotube layers. More precisely, it was found that the configuration of two parallel Ti plates being in close contact to each other, mounted to the anodic terminal and in parallel with the graphite cathode, favors the formation through electrolysis of multi-layered TiO2 nanotubes. The microscopic observation of multi-layered TiO2 nanotubes was performed through the removal of the upper layer of nanotubes using sonication. This peculiar result was interpreted using existed theories such as First Fick’s law and Nerst diffusion layer in combination with recently published research findings related to the effect of inter-electrode distance.
Mixed silicon–graphite composites were studied as an anode material for LIB. Estimation of the capacity of the composite as a function of silicon mass fraction as well as the lithium mole fraction in the final Li–Si alloy was performed. Based on this estimation, appropriate cycling test was introduced. Possible cycling stability region in terms of Si mass fraction, mole fraction of Li in the Li–Si alloy and average particle size was evaluated.
Potassium and sodium-ion transfer kinetics were compared for the intercalation reactions into the KVPO4F positive electrode material in acetonitrile- and ethylene carbonate-based electrolytes, which implied the formation of different electrode/electrolyte interface structures. The presence of surface layers was found to result in a significantly more pronounced effect on the ion transfer kinetics for K+ compared with Na+, while the barrier layers in K+ electrolytes were demonstrated to be less resistive. Difficulties associated with the stabilization of the electrode material/potassium electrolyte interface under high operating potentials require the application of higher voltage electrolytes. The kinetic trends in three high voltage electrolytes were compared for the potassium (de)intercalation reaction, and the general obstacles to developing a high-voltage potassium-ion battery were identified.
Plate-like Li3V2(PO4)3/C composite is synthesized via a solution route followed by solid-state reaction. The Li3V2(PO4)3/C plates are 40–100nm in thicknesses and 2–10μm in lengths. TEM images show that a uniform carbon layer with a thickness of 5.3nm presents on the surfaces of Li3V2(PO4)3 plates. The apparent Li-ion diffusion coefficient of the plate-like Li3V2(PO4)3/C is calculated to be 2.7×10−8 cm2 s−1. At a charge–discharge rate of 3C, the plate-like Li3V2(PO4)3/C exhibits an initial discharge capacity of 125.2 and 133.1mAhg−1 in the voltage ranges of 3.0–4.3 and 3.0–4.8V, respectively. After 500 cycles, the electrodes still can deliver a discharge capacity of 111.8 and 97.8mAhg−1 correspondingly, showing a good cycling stability.
The distributions of current density and potential of automotive negative plate were studied by measuring the IR drop in the H2SO4 solution between the positive and negative plates. At the beginning of discharge, the distributions of current density, potential and polarization resistance are uniform. In the later stage, high polarization appears at the top and bottom of the negative plate and the current density falls very quickly in these regions. Therefore, high polarization resistance of the active mass increases very quickly at both the top and bottom of the negative plate. It is mainly caused by the passivation of the negative plate which obviously decreases by constant current charge. At low temperature, at the end of 3 C discharge, the highest polarization and the lowest current density appear farthest away from the lug and at the top of the negative plate.
A new blue-emitting phosphor, Sr1− x Pb x ZnO2, was prepared by a novel adipic acid templated sol–gel route. Photoluminescence and crystalline properties were investigated as functions of calcination temperatures and the Pb2+ doping levels. It was found that under UV excitation with a wavelength of 283 or 317nm, the phosphors gave emission from 374 to 615nm with a peak centered at 451nm. This broad-band was composed of UV and the visible range was attributed to an impurity-trapped exciton-type emission. The maximum emission intensity of the Sr1− x Pb x ZnO2 phosphors occurred at a Pb concentration of x=0.01. The decay time was observed to be ∼33ms for the compound doped with 1mol% Pb prepared at 1000°C. Diffuse reflectance spectra revealed the characteristic absorption peaks and the bandgap energy of SrZnO2 was found to be 3.4eV. SEM analysis indicated that phosphor particles have an irregularly rounded morphology and the average particle size was found to be approximately 1μm.
The changes in the properties of lithium–sulphur cell components (electrolyte, sulphur and lithium electrodes) during cycling are studied by AC impedance spectroscopy. It is shown that during the charge and discharge of lithium–sulphur cells the conductivity of the electrolyte is changed. We believe that the observed changes in the electrolyte conductivity can be explained by the formation of soluble lithium polysulphides by electrochemical reactions. The properties of the electrolyte significantly influence the rate of the electrochemical processes which occur both on the sulphur and lithium electrodes in lithium–sulphur cells.
Nano-structured silicon anodes are attractive alternatives to graphite in lithium-ion batteries; however, despite recent progress in nano-engineered composites, its use remains limited. One of the issues, particularly in silicon-dominated anodes, is the poor Coulombic efficiency of lithium–silicon processes. Previous studies have shown that repeating the amorphous–crystalline hysteretic lithium–silicon phase transformations can abruptly improve irreversibility and eventually minimize cumulative irreversible lithium consumption in exchange of certain parasitic capacity sacrifice. Here, we reveal mechanism behind the phenomenon that the single phase transformation spontaneously and pseudo-topologically transforms nano-structured silicon into quantum-scale frameworks without gravimetric loss. The way it forms is clearly distinct from ever explored formation mechanism of porous nano-structures such as (electro)chemical etching, Kirkendall voiding, and percolation theory. Further, we implanted the structural transformation feature into lithium-ion full cells, largely redesigning the conventional one, by modulating cathode/anode capacity loading balance and prelithiation dose in the anode to embed the unique feature in the cells. We show that the cell preferentially triggers the efficient irreversibility-depletion phenomenon upon cycling and consequently outperforms conventional silicon-based cells.
In our continued efforts to find an electrically rechargeable zn/air secondary battery, we report the unique behavior of a zinc oxide anode in the presence of additives such as phosphoric acid, tartaric acid, succinic acid and citric acid. These additives were added to the electrolyte, which is an 8.5M KOH solution containing 25g of ZnO and 3000ppm of polyethylene glycol in 1l of water. In zn/air systems there are two main problems namely the hydrogen overpotential and dendrite formation during recharging. Investigations have studied in detail both of the problems in order to overcome them. The results obtained in presence of additives are compared with the behavior of the electrolyte 8.5M KOH in the absence of additives. It has been concluded that the hydrogen overpotential is raised enormously while dendrite formation is reduced to some extent. Out of the four acids studied, the order of increase in hydrogen overpotential is: tartaric acid>succinic acid>phosphoric acid>citric acid. The prevention of dendrite formation follows the order: citric acid>succinic acid>tartaric acid>phosphoric acid.
Epidemiological evidence suggests that chronic consumption of fruit-based flavonoids is associated with cognitive benefits; however, the acute effects of flavonoid-rich (FR) drinks on cognitive function in the immediate postprandial period require examination. The objective was to investigate whether consumption of FR orange juice is associated with acute cognitive benefits over 6 h in healthy middle-aged adults.
In this work, Lithium rich layered oxide Li1.17Ni0.2Co0.05Mn0.58O2 (LNCMO) is prepared and coated with Li3V2(PO4)3 (LVP) by a chemical deposition method. The surface modification with LVP is introduced into Li-rich layered oxides LNCMO for the first time. After 100 cycles of charging and discharging at various rates, the Li3V2(PO4)3-coated Li1.17Ni0.2Co0.05Mn0.58O2 (LVP-coated LNCMO) (5wt%) still provides a large capacity of 261.4mAhg-1, much higher than the pristine LNCMO (211.5mAhg-1). At 5C rate, the LVP-coated LNCMO exhibits a stable cyclic capacity of 153.4mAhg-1, higher than 114.1mAhg-1 of the pristine LNCMO. The electrochemical impedance spectroscopy (EIS) analysis demonstrates the LVP coating layer can suppress interaction between the cathode surface and the electrolyte and enhance the kinetics of lithium-ion diffusion, contributing to the stable cyclic performance with more cyclic capacity as well as at the high current density.