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In this work, we proposed using titanium dioxides (TiO2) with oxygen vacancies (H-TiO2) as cathode catalysts to improve the electrochemical performance of non-aqueous lithium-air batteries. Such H-TiO2 catalysts were attained by a facile heat treatment of rutile TiO2 and the existence of vacancies was confirmed by Raman spectra and X-ray photoelectron spectroscopy (XPS). It was demonstrated that due to the presence of defects which can facilitate the adsorption and dissociation of oxygen, the in-house lithium-air battery with H-TiO2 can be discharged at the current densities of 0.3 and 0.5mAcm−2 while maintaining the specific capacities of 3.2 and 2.8mAhcm−2, respectively, much higher than those of the batteries without catalysts or with pristine rutile TiO2. In addition, the cycling test showed that the battery with H-TiO2 can undergo 400 and 372 cycles, respectively, at the current densities of 0.3 and 0.5mAcm−2 with a fixed specific capacity of 0.1mAhcm−2 and a cutoff discharge voltage of 2.0V.
This paper presents the preparation and characterization of a series of PEO-PMMA composites containing different lithium salts (LiClO4 or LiTFSI) with or without nano-Al2O3. Nano-Al2O3 is added to the polymer electrolytes to alter the morphology, ionic conductivity, interfacial and thermal shrinkage properties. Nano-Al2O3 can effectively improve the stability of the polymer electrolyte membrane interface. The tensile strength of the PEO-PMMA-LiTFSI-Al2O3 electrolyte membrane is 3.24MPa at room temperature. The study shows that the ion conductivities at room temperature for PEO-PMMA-LiTFSI (EO/Li+ =10) and PEO-PMMA-LiTFSI-Al2O3 (EO/Li+ =10) are 6.71×10−7 S/cm and 9.39×10−7 S/cm, respectively. A good dimensional stability was observed for PEO-PMMA-LiTFSI with a thermal shrinkage of 8.7%. The electrochemical windows of PEO-PMMA-LiTFSI and PEO-PMMA-LiTFSI-Al2O3 are all stable up to 4.6V versus Li+/Li, which makes them good electrolyte candidates of lithium ion batteries with high-potential cathodes.
Gait and balance deficits are reported in adults with HIV infection and are associated with reduced quality of life. Current research suggests an increased fall-incidence in this population, with fall rates among middle-aged adults with HIV approximating that in seronegative elderly populations. Gait and postural balance rely on a complex interaction of the motor system, sensory control, and cognitive function. However, due to disease progression and complications related to ongoing inflammation, these systems may be compromised in people with HIV. Consequently, locomotor impairments may result that can contribute to higher-than-expected fall rates. The aim of this review was to synthesize the evidence regarding objective gait and balance impairments in adults with HIV, and to emphasize those which could contribute to increased fall risk.
We report herein on the possibility of using ionic liquids (ILs) as additives to conventional electrolyte solutions, based on alkyl carbonates and LiPF6 for attenuating thermal reactions in Li battery systems. As a model, a Li–Li0.5CoO2 system was used. The ionic liquids chosen included cations based on derivatives of pyrrolidinium and imidazolium, and the anions bioxalato borate (C4O8B−, BOB), (CH3SO2)2N− (TFSI), and PF3(C2S5)3 − (FAP). The thermal behavior of solutions alone, solutions with Li metal, Li0.5CoO2 and Li metal+Li0.5CoO2 was studied. It was found that the presence of 10% of ILs, with derivatives of pyrrolidinium cations and FAP or TFSI anions in standard EC–DMC/LiPF6 solutions, improves considerably the thermal stability of Li0.5CoO2 in electrolyte solutions. The onset temperatures of the thermal reactions of Li0.5CoO2 with solution species are higher and their heat evolution is considerably lower, when they contain these ionic liquids as additives. This finding opens the door for further studies and optimization of the use of selected ILs as additives that may improve the safety features of Li-ion batteries.
As part of a Berlin-based research consortium on health in old age, the OMAHA (Operationalizing Multimorbidity and Autonomy for Health Services Research in Aging Populations) study aims to develop a conceptual framework and a set of standardized instruments and indicators for continuous monitoring of multimorbidity and associated health care needs in the population 65 years and older.
0.5-mol% and 1.0-mol% W-doped Li[Ni0.90Co0.05Mn0.05]O2 cathodes are synthesized by introducing W in the [Ni0.90Co0.05Mn0.05](OH)2 precursor stage. The W doping considerably improves the cycling stability at 2.7–4.3 V (96% at 100 cycles) and even at 4.4 V (94.5% at 100 cycles) with minimal reductions in the initial capacity (235 mA h g−1 at 4.4 V) of the 1.0-mol% W-doped. The superior chemical stability of the 1.0-mol% W-doped Li[Ni0.90Co0.05Mn0.05]O2 cathode is confirmed by an accelerated thermal aging test (storing of the highly delithiated cathode in the electrolyte at 60 °C). The observed improvement in the performance of the W-doped Li[Ni0.90Co0.05Mn0.05]O2 cathode is attributed mainly to bulk structure stabilization through the reduction in the internal strain, suppressing the detrimental formation of microcracks. Moreover, the spinel-like phase on the periphery of the primary particles acts as a buffer to protect the particle interior from the electrolyte attack. The applicability of the 1.0-mol% W-doped Li[Ni0.90Co0.05Mn0.05]O2 cathode for a high-energy-density Li-ion battery for electric vehicles is partially verified as it maintains 89% of its initial capacity after 500 cycles in a full-cell cycled at a high voltage of 4.3 V (vs. graphite), compared to the value of only 60% for the pristine cathode.
In this paper, Poly (acrylic-co-maleic) acid (PAMA) is used as a dispersant to improve the stability of electrodes slurries for large scale processing of Silicon based negative composite electrode. The stability and homogeneity of the slurries are characterized using different techniques. Sedimentation test, electrical measurement, SEM-EDX observations as well as rheological measurements show that a more homogeneous distribution of carbon black (CB) inside the stack of Si particles is reached with presence of PAMA. However, the amount of PAMA is limited due to the competition in the adsorption of PAMA and Carboxylmethyl cellulose (CMC) at the surface of the CB particles. Upon cycling with capacity limitation, the optimized electrode formulation at lab scale could achieve more than 400 cycles with surface capacity ∼2.5–3.3 mAh cm−2. At the pilot scale, the improvement of adhesion of the tape to the current collector by using Styrene-co-Butadiene rubber copolymer latex (SB) helps to maintain long cycle life while calendaring is detrimental to electrochemical properties.
As a potential multi-electron electrode material for next generation lithium ion batteries, iron fluoride (FeF3) and its analogues are attracting much more attentions. Their microstructures are the key to achieve good electrochemical performances. In this work, FeF3·3H2O nano-flakes precursor with high crystallinity and flower-like morphology is synthesized successfully, by a liquid precipitation method using Fe(NO3)3·9H2O and NH4HF2 as raw materials. The formation and the crystal growth mechanisms of the FeF3·3H2O precursors are investigated and discussed. After different temperature heat-treatment and followed by ball-milling with Super P, the as-prepared FeF3.0·33H2O/C and FeF3/C nanocomposites are used as cathode materials for lithium ion batteries. The FeF3.0·33H2O/C nanocomposite exhibits a noticeable initial specific capacity of 187.1 mAh g−1 and reversible specific capacity of 172.3mAhg−1 at .1C within a potential range of 2.0–4.5V. The capacity retention is as high as 97.33% after 50 cycles. Combined with HRTEM test, it confirms that the hydration water is not harmful but useful, namely, the tunnel phase formed with the hydration water is crucial to unobstructed Li+ diffusion, and therefore leading to excellent electrochemical performances.
Polyazulene (PAz) was electrosynthesized in the ionic liquid N,N-butyl-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP][Tf2N]) and characterized using electrochemical methods. By using [BMP][Tf2N] as the electrolyte we obtained films with improved electrochemical and morphological properties compared to films electrosynthesized in an acetonitrile-based electrolyte solution. Composite films consisting of drop cast C60 and electrosynthesized PAz were also investigated in [BMP][Tf2N] using electrochemical methods, UV–vis and SEM and the results were compared to similar films prepared in acetonitrile. The use of ionic liquids made it possible to study the redox reactions of C60 at room-temperature and in an extended cathodic potential range. In comparison to pure PAz the presence of C60 in the composite film improved the charge storing ability. Electrosynthesis in [BMP][Tf2N] resulted in composite films with a lower degree of charge trapping compared to composite films synthesized in organic media.
This paper presents a high-resolution automated meter reading system for residential gas meters, which can be used to record gas consumption for each appliance. The mechanical operation of an industry-standard residential gas meter is characterized, and the internal metering mechanism analyzed to develop a system to non-intrusively monitor gas consumption of individual appliances by resolving small amounts of gas usage at the meter. The system can be retrofitted to an existing gas meter with a module that includes a high-resolution encoder to collect gas flow data, and a microprocessor to analyze and classify appliance load profiles. This approach provides a number of attractive features including low cost, easy installation and integration with existing meter reading technologies. This system enables gas utilities to provide real-time feedback to customers on gas usage by appliance.
Every year the number of installed wind power plants in the world increases. The horizontal axis wind turbine is the most common type of turbine but there exist other types. Here, three different wind turbines are considered; the horizontal axis wind turbine and two different concepts of vertical axis wind turbines; the Darrieus turbine and the H-rotor. This paper aims at making a comparative study of these three different wind turbines from the most important aspects including structural dynamics, control systems, maintenance, manufacturing and electrical equipment. A case study is presented where three different turbines are compared to each other. Furthermore, a study of blade areas for different turbines is presented. The vertical axis wind turbine appears to be advantageous to the horizontal axis wind turbine in several aspects.
This paper proposes a new approach to designing inbound material collection routes that considers pick-up frequency and spatial design as joint decisions to minimize total logistics (transportation plus inventory) cost. The clustering-based optimization uses an approximation to the actual cost of a routing solution without actual route construction. We show that the problem is analogous to a single-source fixed-charge facility location problem, and near-optimal solutions can be found using an efficient heuristic algorithm. Tests show the effectiveness of how this model is formulated and a case study demonstrates that substantial total cost savings can be achieved in realistic applications.
This paper develops an equilibrium modeling framework that captures the interactions among availability of public charging opportunities, prices of electricity, and destination and route choices of plug-in hybrid electric vehicles (PHEVs) at regional transportation and power transmission networks coupled by PHEVs. The modeling framework is then applied to determine an optimal allocation of a given number of public charging stations among metropolitan areas in the region to maximize social welfare associated with the coupled networks. The allocation model is formulated as a mathematical program with complementarity constraints, and is solved by an active-set algorithm. Numerical examples are presented to demonstrate the models and offer insights on the equilibrium of the coupled transportation and power networks, and optimally allocating resource for public charging infrastructure.
Generalised Joint Hypermobility (GJH) is a hereditary condition with an ability to exceed the joints beyond the normal range. The prevalence of GJH in the adult population and its impact on upper body musculoskeletal health and quality of life has mostly been studied in selected populations. The aims of this study were therefore, firstly to study the prevalence of GJH and GJH including shoulder hypermobility (GJHS), in the general Danish adult population; secondly to test the associations between GJH or GJHS and upper body musculoskeletal symptoms and health-related quality of life (HRQoL).
Hybrid electrochemical storage devices comprising a capacitor-type positive electrode and a battery-type negative electrode are regarded as a promising concept combining high power density with high energy density. In this work Fe3O4/reduced graphene oxide (rGO) nanocomposite has been synthesized and applied as negative electrode in an electrochemical energy storage device being a serial internal hybrid of an alkaline battery and an electrochemical double layer capacitor (EDLC). Beneficial effect of graphene on the performance of magnetite electrode has been evidenced by means of cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy techniques. Unlike in a vast majority of reports, magnetite capacitances have been determined in real electrochemical devices, against activated carbon as positive electrode. In three-electrode cells with activated carbon as the positive electrode magnetite has been found to exhibit from 65 to 83 F g−1 for the rGO content from 9.7 to 27.8 %. The maximum voltage of a capacitor with Fe3O4/rGO negative electrode has been established as 1.0 V, which is higher than typical value of 0.8 V known for the symmetrical carbon-based capacitors.
A third generation promoter probe shuttle vector pKG was constructed, using the green fluorescent protein as a reporter, for in situ evaluation of Deinococcal promoter activity in Escherichia coli or Deinococcus radiodurans. The construct yielded zero background fluorescence in both the organisms, in the absence of promoter sequences. Fifteen Deinococcal promoters, either harbouring Radiation and Desiccation Response Motif (RDRM) or not, were cloned in vector pKG. Only the RDRM-promoter constructs displayed (i) gamma radiation inducible GFP expression in D. radiodurans, following gamma irradiation, (ii) DdrO-mediated repression of GFP expression in heterologous E. coli, or (iii) abolition in GFP induction following gamma irradiation, in pprI mutant of D. radiodurans. Utility of pKG vector for real-time in situ assessment of Deinococcal promoter function was, thus, successfully demonstrated.
Nanostructured early-transition-metal nitrides possess high capacitances that are consistent with a pseudocapacitive storage mechanism. Prior publications suggest that the mechanism involves the interactions between protons and the metal. This paper describes the use of in-situ small angle neutron scattering as a function of the potential applied to the electrode and ex-situ physical and electrochemical techniques to determine specific details regarding the storage mechanism for high-surface-area Mo nitride (γ-Mo2N) in 0.1 mol dm−3 H2SO4 electrolyte. The results demonstrate that the pseudocapacitance involves a proton-coupled electron transfer (2e- for every H+) via micropores, which is accompanied by the reduction/oxidation of Mo. These results suggest that capacitances in excess of 1500 Fg−1 in 1.2 V could be achieved in aqueous acidic electrolytes.
The layered Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material is successfully synthesized via an optimized sol–gel method. With oxalic acid instead of citric acid as the chelating agent, the amount of chelating agent used in this experiment is only 36% of the traditional weight. Segmented sintering method is adopted to decrease the calcination temperature and reduce the calcination time. X-ray diffraction spectrometry (XRD) and scanning electron microscopy (SEM) are used to characterize the structure and micromorphology of the material. Meanwhile, charge–discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are employed to explore its electrochemical performance. Our results demonstrate that Li[Li0.2Mn0.54Ni0.13Co0.13]O2 electrode delivers a high reversible capacity of 277.3mAhg−1 and keeps excellent capacity retention of 98.4% after 50 cycles when tested at a 0.1C rate within the potential range of 2.0–4.8V at room temperature.
LiMnPO4 nanoplates with a thickness of ca. 13nm have been synthesised by a facile solvothermal approach in mixed water-DEG (diethylene glycol) solvents with the mediation of CTAB (cetyltrimethyl ammonium bromide). The coordinative effect of CTAB and DEG promotes the crystal orientation growth of LiMnPO4 along ac plane. The structure and morphology of the product were characterized by XRD, SEM, TEM, BET, FT-IR and Raman spectra. A possible formation mechanism of LiMnPO4 nanoplates assembled in layer-by-layer style is put forward on the basis of the above characterization results. A continuous and uniform carbon layer is coated on the surface of the LiMnPO4 nanoplates after heat treatment with sucrose. The obtained LiMnPO4/C composite exhibits high discharge capacities of 148.6mAhg−1 at 0.1C, 127.6mAhg−1at 1C and 93.8mAhg−1 at 5C and it possesses excellent cycling performance with capacity retention ratios of 96.9% and 92.7% after 100 cycles and 500 cycles at 0.1C and 1C, respectively.
Wind power fluctuations are typical of small size wind farms and may be a limiting factor in isolated small-size systems. An electric storage can be used to mitigate these fluctuations and enable the use of wind energy to provide energy to remote communities or microgrids. This study compares the performance of Li-Ion batteries and flywheels in abating the ramp rates of the power produced by a wind turbine. Production data was generated from actual wind measurements over one year. The capability of ramp abatement by varying storage capacity, power rating and ramp rate thresholds was investigated. The storage technologies were compared from the technical and economic point of views by means of a multi-objective optimization approach that showed the optimal trade-off between abatement capability and costs. The costs of storage periodic replacement, due to the degradation induced by a cycling operation, was also estimated. Results suggest that the abetment of wind power ramps up to 80% can be done at a relatively low price (between 5 and 10 k€). In this case flywheels outperform batteries in term of cost. If a higher abatement effectiveness is required (around 90%) the storage cost quickly increases. In this case the battery outperforms the flywheel and provide the same performance at much lower cost. If strict requirements are assumed, i.e. maximum permitted fluctuations are lower than 5% of turbine rated power, an abatement effectiveness up to 95% is achievable, but the cost may be as high as 25 k€ per year. Otherwise, in case of a maximum permitted fluctuation lower than 10%, abatement effectiveness over 92% is hardly achieved (the cost is over 30 k€ per year). For abatements around 90%, an annual cost between 15 and 20 k€ may be found using batteries rather than flywheels.
We reconstruct Frédéric Joliot and Irène Curie’s discovery of artificial radioactivity in January 1934 based in part on documents preserved in the Joliot–Curie Archives in Paris, France. We argue that their discovery followed from the convergence of two parallel lines of research, on the neutron and on the positron, that were focused on a well-defined experimental problem, the nuclear transmutation of aluminum and other light elements. We suggest that a key role was played by a suggestion that Francis Perrin made at the seventh Solvay Conference at the end of October 1933, that the alpha-particle bombardment of aluminum produces an intermediate unstable isotope of phosphorus, which then decays by positron emission. We also suggest that a further idea that Perrin published in December 1933, and the pioneering theory of beta decay that Enrico Fermi also first published in December 1933, established a new theoretical framework that stimulated Joliot to resume the researches that he and Curie had interrupted after the Solvay Conference, now for the first time using a Geiger-Müller counter to detect the positrons emitted when he bombarded aluminum with polonium alpha particles.
In a bid to reduce infection rates by COVID-19 the authorities in some countries, in collaboration with medical regulators and experts, have employed digital technologies to control and regulate citizens’ behavior. Public opinion and the public’s compliance with these technologies come into play here. The objective of the present study was to examine attitudes expressed in the public discourse toward the use of digital technologies to control people’s behavior during the COVID-19 pandemic, as reflected in the media.
Extensive retrograde memory deficits have been detected in patients with temporal lobe epilepsy (TLE) and in patients who have undergone temporal lobectomy (TL). To date, no group study has used a prospective longitudinal design. We assessed memory for public and autobiographical facts and events in patients (n =15) with focal left- or right-sided TLE before and after TL using a battery of tests that covered the life span. Patients who underwent TL demonstrated material-specific memory decline in retrograde memory. Left TL was associated with a significant drop in recall of famous people’s names. Patients who underwent right TL exhibited a significant decline in the recall of autobiographical events from across the life span. Our study indicates for the first time that TL is associated with a risk of mild, material-specific retrograde memory decline. Verifications with a larger sample size and other measures of remote memory are needed.
The first intelligent COVID-19 lockdown resulted in radical changes within the tertiary educational system within the Netherlands. These changes posed new challenges for university students and many social welfare agencies have warned that it could have adverse effects on the social wellbeing (SWB) of university students. Students may lack the necessary social study-related resources (peer- and lecturer support) (SSR) necessary to aid them in coping with the new demands that the lockdown may bring. As such, the present study aimed to investigate the trajectory patterns, rate of change and longitudinal associations between SSR and SWB of 175 Dutch students before and during the COVID-19 lockdown. A piecewise latent growth modelling approach was employed to sample students’ experiences over three months. Participants to complete a battery of psychometric assessments for five weeks before the COVID-19 lockdown was implemented, followed by two directly after and a month follow-up. The results were paradoxical and contradicting to initial expectations. Where SSR showed a linear rate of decline before- and significant growth trajectory during the lockdown, SWB remained moderate and stable. Further, initial levels and growth trajectories between SSR and SWB were only associated before the lockdown.