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We systematically investigated the tuning of the reduction potentials (E0 ) for the first row transition metal (M=Cr, Mn, Fe, Co, Ni) complexes with the functionalized 1,4,7-Triazacyclononane-N,N',N”-triacetate (TCTA) ligands by means of DFT calculations. To predict reliable E0 , the modified UB3LYP functional and equilibrium concept between high and low spin states were utilized. The functional groups NH2, CN, −F, and NO2 were attached to the carbon atoms carefully selected by considering the LUMO and steric hindrance. Based on firmed accuracy of DFT calculations, finally we obtained the calculated E0 for a series of complexes. It was found that electron donating group such as NH2 will cause a negative shift of E0 while electron withdrawing groups have the opposite effect. The overall trend of the calculated E0 s according to ligand modifications were predicted to have the order as −NH2 < Pristine <−F≈−CN <−NO2. In addition, optimized geometries, LUMO, vertical electron attachment and energy components constituting E0 were discussed in detail to assist the further understanding for E0 s. Consequently, we suggested that 16 complexes can play a role as an electrolyte in aqueous redox flow battery. They can be classified into 5 groups having similar E0 ranges: Group I (- 0.6V∼− 0.7V), Group II (around 0.0V), Group III (around 0.3V), Group IV (0.6∼0.8V) and Group V (1.1∼1.2V). Especially, it is expected that [MnLF], [MnLCN] and [NiLNH2] can be used as promising catholyte candidates possibly possessing high E0 s which almost reach to the reduction potential limitation 1.25V in aqueous redox flow battery. Our systematic approach to tune E0 can be applied to the design of other complexes via rational ligand modification.
Publisher Summary Water is a common vehicle for the transmission of many enteric viruses. Enteric viruses survive longer in fresh and marine water than coliform bacteria, which are used to monitor water quality. In marine and other surface waters, numbers of enteric viruses are often too low to be detected in unconcentrated samples. Therefore, large volumes of water must be concentrated by adsorption/filtration and elution (desorption) before analysis. More than 100 types of human pathogenic viruses are present in fecally contaminated water, and are detected by the current available methods. The detection of adenoviruses, hepatitis A virus, astroviruses, and rotaviruses by cell culture is possible; however, the methods are tedious and less often used. Nucleic acid hybridization and the polymerase chain reaction (PCR) are used for detecting human viruses and other fastidious microbial pathogens in the environment. Molecular detection methods are important in studying the occurrence of Hepatitis A and Norwalk-like viruses, which are epidemiologically important pathogens but do not produce cytopathogenic effects (CPE) readily in cell culture. Molecular techniques have also enhanced the speed and sensitivity of detection for the more routinely cultured enteroviruses.
One of the challenges for the success of electric vehicles is to achieve a non aqueous Li-O2 battery efficient in the oxidation of solid Li2O2 during battery charging. Bruce et al. have proposed that soluble tetrathiofulvalene (TTF) in the electrolyte, makes it possible to recharge the battery at high current densities and low over-potential. We disclose here a detailed study of Li2O2 and solvent degradation products oxidation on gold electrode in 0.1M LiPF6 DMSO electrolyte with soluble TTF using a variety of techniques: rotating ring disk electrode (RRDE), scanning electrochemical microscopy (SECM), electrochemical quartz crystal microbalance (EQCM) and atomic force microscopy (AFM). The experimental evidence demonstrates that it is possible recover a clean Au surface using TTF as a soluble catalyst that titrates the surface products formed during the O2 reduction.
The electrolyte solution for a primary nonaqueous lithium metal air battery is optimized. A novel oxygen selective membrane consisting of Teflon coated fiberglass cloth is used to prevent corrosion of the lithium metal negative electrode by water vapor during discharge in ambient air. The air electrode capacity is increased by increasing the amount of dimethyl carbonate and methoxybenzene in the electrolyte solvent, increasing the lithium tetrafluoroborate concentration to 1.5M, and adding 4 mass % pentafluorophenylboron oxalate. Cells using either the starting or optimized electrolyte were discharged at a current density of 0.1mAcm−2 in air at 23°C and 20% relative humidity. The discharge capacity (averaged for five discharges using each electrolyte solution) was increased by a factor of 2.2 for the cells using the optimized electrolyte solution of 1.5M lithium tetrafluoroborate in propylene carbonate:dimethyl carbonate:methoxybenzene (1:5:1 by volume)+4 mass % pentafluorophenylboron oxalate.
Multi-walled, single-walled and double-walled carbon nanotubes as well as graphene can be doped with boron and nitrogen. B2H6 has been generally used as the boron source while NH3 or pyridine is employed as the nitrogen source. Doping carbon nanotubes and graphene with boron and nitrogen brings about significant changes in the electronic structure and properties. Such doping not only results in desirable properties but also allows manipulation of properties for specific purposes. Doping with boron- and nitrogen-causes marked changes in the Raman spectra of the carbon nanostructures. In this article, we present the synthesis, characterization and properties of boron- and nitrogen-doped carbon nanotubes and graphene.
There is evidence for a relevant role of inflammation in the pathogenesis of Parkinson’s disease (PD). Mutations in the LRRK2 gene represent the most frequent genetic cause for autosomal dominant PD. LRRK2 is highly expressed in macrophages and microglia suggesting an involvement in inflammatory pathways. The objectives are to test (1) whether idiopathic PD and LRRK2-associated PD share common inflammatory pathways or present distinct profiles and (2) whether non-manifesting LRRK2 mutation carriers present with similar aspects of inflammatory profiles as seen in PD-affected patients.
In the acute medical care hospital setting, nursing the sick and dying is both physically and emotionally demanding, making acute medical care hospital nurses more vulnerable to Compassion Fatigue (CF) or Secondary Traumatic Stress (STS). If not addressed in its earliest stages, CF can adversely change the caregiver’s ability to provide compassionate care. It has been shown that Self-Compassion (SC) can be beneficial for the caregiver, with corresponding benefits for the individual needing care. However, the relationship of this attribute to CF in the acute medical care hospital nursing setting has not been intensively studied. This study explores the environmental and psychosocial factors affecting the prevalence and levels of CF in acute medical care hospital nursing staff and whether SC can be used as a coping strategy that enables nurses to mitigate the prevalence and levels of CF.
The hierarchical porous carbon aerogel (CA) with vanadium nitride (VN) was effectively prepared via a facile in-situ method with organic acid catalyzing and non-supercritical drying. The surface morphology and structure of the VN/CA (VCA) composites, and the electrochemical performance of these composites based sulfur cathodes were investigated systematically. This mono-dispersed microsphere composite presents hierarchical pore and uniform dispersion of vanadium nitride, and effectively immobilizes the polysulfides due to the synergistic effects between the VN and CA matrix. Moreover, the VN on the CA has catalytic effect on the electrode reaction, displaying high discharge voltages. In particular, a higher initial discharge capacity of 1279mAhg−1 can be obtained at 0.2C, and it retains 1001mAhg−1 after 100 cycles. Even at a higher rate of 1C, the capacity still delivers 802mAhg−1 after 100 cycles.
Thin film electrodes for rechargeable lithium batteries were prepared by a sol–gel method with poly(vinylpyrrolidone) (PVP). The LiTiO and LiMnO sols were successfully prepared by using PVP. The sol deposited on Au substrate by a spin coater was converted to a gel film through the spin coating process. The LiTiO and LiMnO gel films were heated at 600°C for 1 h and 800°C for 1 h, respectively. The prepared thin films were characterized by X-ray diffraction and scanning electron microscopy. From these results, it was found that the prepared electrode films were Li4/3Ti5/3O4 and LiMn2O4, respectively. The electrochemical properties of the prepared electrode films were evaluated by using charge and discharge measurements and cyclic voltammetry in a mixed solvent of ethylene carbonate and diethyl carbonate (1:1 v/v) with 1.0 M LiClO4. From cyclic voltammograms, the apparent chemical diffusion coefficients for Li+ ions in the oxide films (D Li) were estimated to be 6.8×10−11 cm2 s−1 for Li4/3Ti5/3O4 and 7.1×10−12 cm2 s−1 for LiMn2O4, respectively. Excellent electrochemical properties were observed in discharge and charge tests. From these results, it can be said that the PVP sol–gel method is very useful to prepare thin film electrodes.
ABSTRACT Advanced materials for energy conversion and storage are central to clean and reliable energy research. Herein, three-dimensional (3D) architectures composed of MoS2-graphene hybrid nanosheets are synthesized via a simple solvothermal method for this purpose. The architectures are self-assembled with hybrid nanosheets, which are fabricated through the in situ growth of few-layer MoS2 nanosheets on the surface of graphene substrates. Rooted in the intriguing advantages of sheet-on-sheet structures and 3D features, the composite materials exhibit improved electrochemical lithium storage performances when used as anode materials, in terms of high reversible capacity, superior cycling stability (904mAhg−1 after 200 cycles at 200mAg−1), and high rate capability. It is also employed as integrated electrode for electrochemical water splitting and delivers remarkably enhanced catalytic performance for hydrogen evolution, such as low onset overpotential (110mV), small Tafel slope (47mVdecade−1), and stable cycling performance.
In order to adapt lead-acid batteries for use in hybrid electric vehicles, its specific energy must be improved. Specific energy is greatly dependant on active material utilization. In this study, we improve active material utilization in positive electrodes by the addition of electronically conductive additives. Titanium silicide particles (<44μm diameter), titanium dioxide fibers (<10μm, diameter), and titanium wire (76μm, diameter) were incorporated into the positive electrode and each of their effects on discharge capacity and utilization of active material were examined. The percent mass of each additive was varied from 2–5%. Results indicate that titanium wire at 2.3wt.% had the optimal effect of increasing the utilization by 12.3% (57 to 64% utilization) relative to control with no additive at a slow discharge rate (10mAcm−2) without detrimental effect at fast discharge rate (50mAcm−2). This additive also features reduction in weight and formation enhancement.
Multi-walled carbon nanotubes functionalized by carboxylic groups, exhibit better affinity towards TiO2 (P90, Degussa) as compared to that of pristine nanotubes. Also the electrochemical performance of TiO2 is improved by nanotube networking, but the Li-storage capacity of TiO2 is unchanged. Whereas the composite of TiO2 with non-functionalized nanotubes demonstrates simple superposition of the behavior of pure components, the composite with functionalized nanotubes shows unique faradaic pseudocapacitance which is specific for this composite only. The surface functionalization of nanotubes enhances charge storage capacity and reversibility of a composite with LiMnPO4 (olivine), but mediates also the electrolyte breakdown at potentials >4.2V. Whereas the electrochemical activation of LiMnPO4 (olivine) by functionalized nanotubes is quite modest, excellent performance was found for LiFePO4 (olivine) in composite materials containing only 2wt% of functionalized nanotubes.
Introduction Gilles de la Tourette syndrome (GTS) is a childhood-onset neuropsychiatric disorder characterised by multiple tics and often associated with behavioural problems. Although there is evidence of significantly reduced self-esteem in children and adolescents with GTS, little is known about perceived self-concept and its clinical determinants at the transition age between adolescence and adulthood. We therefore set out to investigate self-concept in a clinical sample of young patients with GTS at this crucial age for personal development. Methods In addition to standard demographic and clinical data, we collected self-ratings using a standardised battery of psychometric instruments, as well as the Multidimensional Self Concept Scale, a comprehensive questionnaire developed to assess self-concept in subjects aged 9– to 19 years, tapping into the social, competence, affect, academic, family, and physical domains. Results We found that patients diagnosed with at least one co-morbid psychiatric disorder (“GTS-plus” phenotype) reported significantly lower self-concept than patients with “pure GTS”, whereas tic-related variables had no impact on self-concept. Anxiety symptoms were the main determinants of self-concept, especially trait anxiety with regard to social and affective domains. Affective symptoms could also have a negative impact on the physical, affective, competence, and social domains of self-concept. Conclusion Routine screening for anxiety and affective symptoms should be recommended in all patients with GTS seen at transition clinics from paediatric to adult care, in order to implement effective treatment interventions whenever possible.
Being considered as a high Li-ion mobility material, Nasicon structured Li1.5Fe0.5Ti1.5(PO4)3 phosphate material was synthesized via sol-gel route and electrochemically tested as electrode material for lithium-ion batteries. The material was tested in half-lithium electrochemical cells, within two voltage windows, 1.5–3.0 V and 0.5–3.0 V, and delivered first discharge capacities of 129 mAh/g and 567 mAh/g, respectively. Raman spectroscopy was used to confirm the material's structure before and during cycling. In addition, a comparative study of the electrochemical performance by the use of two different binders (PVDF and CMC), was conducted and showed a significant change in the electrochemical performance due to the change of the binder. Electrochemical impedance spectroscopy was used to evidence the electrodes' interface changes during cycling.
The structural changes of the Cr-doped and undoped LiMn1.5Ni0.5O4 crystallized in the initial disordered phase with space group of Fd 3 ¯ m have been investigated during the galvanostatic charge/discharge process at C/24 rate by using in-situ X-ray diffraction (XRD) measurements. The de-intercalation of lithium proceeds through a series of first-order phase transitions with two regions of two-phase coexistence. The phase diagram is analyzed and discussed, together with the differences among different results reported in the literature to distinguish between general intrinsic properties of spinel and sample-dependent properties due to deviation from stoichiometry, strain field effects, degree of cation ordering, and out-of-equilibrium effects. We argue that the Cr-doping stabilizes the lattice without impacting the capacity significantly, but decreases the energy density.
Mobile communication has become the major choice of personal communication today. With the rapid proliferation of wireless network technologies, mobile users can communicate through more and more different wireless networks. In such a heterogeneous wireless network environment, traditional wisdom is to ensure mobile users always best connected (ABC) to one of their nearby available networks. However, the ABC strategy may be sub-optimal as the cost and quality of multimedia communication depends not only on the access network of the caller (source) but also on that of the callee (destination). Thus, intelligently selecting a best network connection, or a source and destination access network pair, for users is necessary in next generation multimedia communication, in which various media types, such as voice, video and data, are related and jointly contribute to the communication quality and cost. This paper utilized Analytic Network Process (ANP) to model the problem of call setup strategy for multimedia communication. ANP is powerful in representing complex networked decision process. In the paper, we illustrated, by an example, how ANP sets up calls that fulfill the requirement of users.
For the first time, thermal runaway of charged graphite anodes for K-ion batteries is investigated, using differential scanning calorimetry (DSC) to probe the exothermic degradation reactions. Investigated parameters such as state of charge, cycle number, surface area, and binder demonstrate strong influences on the DSC profiles. Thermal runaway initiates at 100 °C owing to KxC8 – electrolyte reactions, but the K-ion graphite anode evolves significantly less heat as compared to the analogous Li-ion system (395 J g−1 vs. 1048 J g−1). The large volumetric expansion of graphite during potassiation cracks the SEI layer, enabling contact and reaction of KC8 – electrolyte, which diminishes with cycle number due to continuous SEI growth. High surface area graphite decreases the total heat generation, owing to thermal stability of the K-ion SEI layer. These findings illustrate the dynamic nature of K-ion thermal runaway and its many contrasts with the Li-ion graphite system, permitting possible engineering solutions for safer batteries.
Photocatalytic fuel cell (PFC) synergizes photocatalytic degradation of organic pollutants and fuel cell electrochemical reaction to take advantage of the chemical energy stored in the compounds. Herein, we report a novel 3D structured NiFe-layered double hydroxide (LDH)/BiVO4 photoanode and Cu2O-based photocathode for enhancing the efficiency of PFC for the first time. The photoanode was synthesized via a facile hydrothermal and microwave-assisted hydrothermal approach. The experimental results show that the photocurrent density and light harvesting of the PFC increase significantly. The enhanced performance is attributed to the formation of heterojunction at the photoanode resulting in reduction in the interface charge carrier recombination at the NiFe-LDH/BiVO4 junction and lower bandgap energy compared with bare BiVO4. The photocurrent density of the NiFe-LDH/BiVO4 is 90% higher than that of bare BiVO4 using Na2SO3 as the hole scavenger for substrate and 1 M phosphate buffer solution as the supporting electrolyte. The enhanced BiVO4 works as an efficient photoanode in PFC. The open-circuit voltage, short-circuit current and actual maximum power density of the NiFe-LDH/BiVO4-Cu2O/Cu PFC are 0.647 V, 0.196 mA cm−2 and 74 µW cm−2, respectively. The good performance demonstrates that the PFC is a promising technology for wastewater treatment in an eco-friendly, low-cost manner.
This paper analyses inter- and intra-organisational interaction in cases of product development, which involves significantly new technologies that affect core product sub-systems. The analysis shows that in such cases, there is a need to collaborate with suppliers to learn about the new technology. Moreover, provided that the firm's existing technology is still relevant, there is a need to integrate the new technology with existing technologies. Therefore, close supplier interaction has to be associated with close intra-organisational interaction. However, even a case where there is a limited need to integrate the new technology with existing technologies, there is a need to justify the new technology internally and negotiate the process of adopting it within the organisation. The paper thus demonstrates a two-way relationship between organisational characteristics and multi-level technological change. On the one hand, different types of technological changes demand different kinds of R&D organisations and supplier relationships. On the other hand, decisions to implement technological changes are influenced by existing organisational structures and product development philosophies.
NaV2O5, possessing robust, open and large-space layered crystal structure, was recently found as one novel promising intercalation-type high-capacity anode material for Na-ion batteries. To address its difficult issue of morphology control for conventional solid-state method, our group proposed previously a two-step hydrothermal method to controllably synthesize a well-crystallized NaV2O5 mesocrystal. However, this two-step method was still time-costing and a bit complex. In order to further promote its further research development and industrial application, it remains a huge and attractive challenge to explore a simple and time-saving method to synthesize promising NaV2O5. Herein, we propose a facile one-step hydrothermal strategy to realize the short-time synthesis of 3D bundle-like NaV2O5 mesocrystal. In this simple one-step method, sodium oxalate (Na2C2O4) is tactfully designed as simultaneously reducing reagent and Na resource, so that its synthesis time is greatly shortened more than 5 times. Furthermore, the crystal growth mechanism of NaV2O5 mesocrystal is also revealed. Amazingly, the ex-situ XRD measurement reveals that the electrochemical intercalation/deintercalations are reversible and the crystal structure of NaV2O5 is stable. So, NaV2O5 mesocrystal prepared by one-step method exhibit the promising electrochemical performance, and its reversible capacity is up to 360 mAh/g.
In this study we evaluate the economic potential for energy arbitrage by simulating operation and resulting profits of a small price-taking storage device in South Korea’s electricity market. As demand for electricity continues to grow, maintaining a balanced power system at all times has become more challenging in Korea and other developed nations. Along with demand response programs and increased renewable energy utilization, energy storage devices may provide a viable way to contribute to diurnal peak demand shaving. In some parts of the U.S. storage arbitrage has proven to be profitable. Treating a battery’s ability to charge and discharge as a scarce resource, we apply the Hotelling (1931) rule to determine a strategy for maximizing the value of the battery. Results show that present market conditions in South Korea do not provide sufficient economic incentives for energy arbitrage using sodium–sulfur (NaS) or lithium-ion (Li-ion) batteries, with the capital cost of the storage devices exceeding potential revenues.
Li-metal battery (LiMB) has received considerable attention as an alternative energy storage device to Li-ion battery in recent years. However, uncontrolled Li dendrite growth prevents the practical applications of LiMB. Herein, we report the use of concentrated electrolytes based on dual salts of lithium bis(fluorosulfonyl) imide (LiFSI) and lithium difluoro(oxalato) borate (LiODFB) to suppress Li dendrite growth. The compatibility of electrolyte and LiFePO4 cathode was further verified by the long capacity retention and high rate performance of Li/LiFePO4 battery. The superior electrochemical performance was attributed to the concentrated electrolyte, which could simultaneously suppress Li dendrite growth at the anode side and Aluminum (Al) current collector corrosion at the cathode side. This work provides new insights to develop high-performance LiMBs by carefully tailoring the multivariate composition of concentrated electrolyte.