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A dual stage technique employing hot filament chemical vapor deposition (HFCVD) and radio frequency sputtering was used to synthesize SiN/BCNTs (bamboo like carbon nanotubes) on copper substrates. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Electron field emission studies (EFE), charge–discharge, and cyclic voltammetry. The comprehensive characterization is consistent with a nanolayer of amorphous SiN on BCNTs. Field emission experiments confirm the excellent contact of the SiN nanolayer with the surface of the BCNTs necessary for fabrication of a coin cell. Electrochemical testing shows that SiN/BCNT electrode can deliver an initial discharge capacity of 2000mAhg−1 which is higher than the capacity of graphite and the reversible capacity after ten cycles is 300mAhg−1. The cyclic voltammetry results suggest good reversibility with Li during cycling.
Multimedia content boosts the learning trends. This paper is aimed to presents an electronic learning system based on Internet of Things (IoT) for the synchronous and asynchronous communications. The infrastructure of IoT provides the adaptable, scalable and open access for the eLearning paradigm. The multimedia-based IoT-centric environment is suitable to enhance the effectiveness of the delivery of learning contents. Students can take full advantage of 7As of IoT, which provides the opportunity to the students that they can access everything on the internet at any time and place. It creates a flexible eLearning paradigm for the teachers and students. The proposed eLearning modeluses sensors to detect the student location, temperature, and mobile camera to identify the student activeness in thelearning environment. Virtual campuses are controlled from a centralized location that may be called the head office. The MAQAS framework provides the solutions to the problems and analyzes the results for the efficient and connected eLearning paradigm. The MAQAS system is used to answer student’s queries, which are responded to automatically by agent-based question answering system. The results show that the students’ participation towards learning and teacher’s pedagogy are more efficient in synchronous and asynchronous modes. Performance evaluated by comparison to the existing question answering Live QA Trak, Quora Yoda QA Live and AskMSR-QA with MAQAS.
Therapeutic effects of PSD-95 inhibition have been demonstrated in numerous studies of stroke; however only few studies have assessed the effects of PSD-95 inhibitors in traumatic brain injury (TBI). As the pathophysiology of TBI partially overlaps with that of stroke, PSD-95 inhibition may also be an effective therapeutic strategy in TBI. The objectives of the present study were to assess the effects of a dimeric inhibitor of PSD-95, UCCB01-144, on excitotoxic cell death in vitro and outcome after experimental TBI in rats in vivo. In addition, the pharmacokinetic parameters of UCCB01-144 were investigated in order to assess uptake of the drug into the central nervous system of rats. After a controlled cortical impact rats were randomized to receive a single injection of either saline or two different doses of UCCB01-144 (10 or 20 mg/kg IV) immediately after injury. Spatial learning and memory were assessed in a water maze at 2 weeks post-trauma, and at 4 weeks lesion volumes were estimated. Overall, UCCB01-144 did not protect against NMDA-toxicity in neuronal cultures or experimental TBI in rats. Important factors that should be investigated further in future studies assessing the effects of PSD-95 inhibitors in TBI are discussed.
This paper presents the lithium insertion into carbon-rich polymer-derived silicon carbonitride (SiCN) ceramic synthesized by the thermal treatment of poly(diphenylsilylcarbodiimide) at three temperatures, namely 1100, 1300, and 1700°C under 0.1MPa Ar atmosphere. At lower synthesis temperatures, the material is X-ray amorphous, while at 1700°C, the SiCN ceramic partially crystallizes. Anode materials prepared from these carbon-rich SiCN ceramics without any fillers and conducting additives were characterized using cyclic voltammetry and chronopotentiometric charging/discharging. We found that the studied silicon carbonitride ceramics demonstrate a promising electrochemical behavior during lithium insertion/extraction in terms of capacity and cycling stability. The sample synthesized at 1300°C exhibits a reversible capacity of 392mAhg−1. Our study confirms that carbon-rich SiCN phases are electrochemically active materials in terms of Li inter- and deintercalation.
Core–shell Li2Na2Ti6O14@Cu/C is prepared by a preliminary formation of Li2Na2Ti6O14 by solid state reaction and a following coating process with Cu/C layer by thermal decomposition. The amorphous Cu/C coating layer reveals a thickness of 5 nm on the surface of Li2Na2Ti6O14, which improves the electronic conductivity and charge transfer rate of active materials. As a result, Li2Na2Ti6O14@Cu/C shows lower electrochemical polarization and quicker kinetic behavior compared to bare Li2Na2Ti6O14. Cycled at 50 mA g−1, Li2Na2Ti6O14@Cu/C can deliver a reversible capacity of 120.3 mAh g−1 after 50 cycles, which is much higher than the value of 96.8 mAh g−1 obtained by Li2Na2Ti6O14. Even kept at 400 mA g−1, a reversible lithium storage capacity of 76.3 mAh g−1 can be delivered by Li2Na2Ti6O14@Cu/C. The improved electrochemical properties of Li2Na2Ti6O14 are attributed to the electronic conductive Cu/C coating layer on the surface.
Energy accumulation and storage is one of the most important topics in our times. This paper presents the topic of supercapacitors (SC) as energy storage devices. Supercapacitors represent the alternative to common electrochemical batteries, mainly to widely spread lithium-ion batteries. By physical mechanism and operation principle, supercapacitors are closer to batteries than to capacitors. Their properties are somewhere between batteries and capacitors. They are able to quickly accommodate large amounts of energy (smaller than in the case of batteries – lower energy density from weight and volume point of view) and their charging response is slower than in the case of ceramic capacitors. The most common type of supercapacitors is electrical double layer capacitor (EDLC). Other types of supercapacitors are lithium-ion hybrid supercapacitors and pseudo-supercapacitors. The EDLC type is using a dielectric layer on the electrode − electrolyte interphase to storage of the energy. It uses an electrostatic mechanism of energy storage. The other two types of supercapacitors operate with electrochemical redox reactions and the energy is stored in chemical bonds of chemical materials. This paper provides a brief introduction to the supercapacitor field of knowledge.
In the USA, engineers at the Massachusetts Institute of Technology have significantly improved the power output of a direct methanol fuel cell by using a new material that is also considerably less expensive than conventional membranes. Here, we briefly look at the technology.
Scanning electron microscopy (SEM) for the electrode reaction in next-generation battery with ionic liquid (IL) electrolyte, which has both high stability under vacuum and an antistatic nature, is applied to the binder-free high capacity Si anode to observe the morphology change of the Si nanoparticle aggregate active material at different potentials during charge-discharge processes. In the IL electrolyte, 1-ethyl-3-methylimidazolium bis(fluoromethylsulfonyl)amide ([C2mim][FSA]) with 1.0 M lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]), the morphology greatly varied at the plateau observed at 0.200 to 0.070 V (vs. Li(I)/Li) in the charge-discharge curve during the first cycle, suggesting that phase transition of a-Si to c-Li13Si4 is a potential problematic process. After the first cycle, the lithiation process initiated at more positive potential. Similar behavior was also recognized in the Li[TFSA]‒tetraglyme solvate IL electrolyte in a 1:1 molar ratio ([Li(G4)][TFSA]).
The cyclic voltammetry indicated that the oxygen reduction reaction (ORR) proceeded by the four-electron pathway mechanism on larger Ag particles (174nm), and that the ORR proceeded by the four-electron pathway and the two-electron pathway mechanisms on finer Ag particles (4.1nm), simultaneously. The kinetics towards ORR was measured at a rotating disk electrode (RDE) with Ag/C electrode. The number of exchanged electrons for the ORR was found to be close to four on larger Ag particles (174nm) and close to three on finer Ag particles (4.1nm). The zinc-air battery with Ag/C catalysts (25.9nm) was fabricated and examined.
The tungsten niobium oxides that belong to the well-known Wadsley-Roth shear structure have been already studied as the high-performance anode materials over the past several years since these materials can provide the additional vacuum site for accommodating lithium ions. Now, a novel anode material Nb18W16O93 which has a tetragonal tungsten bronze type structure is firstly reported in this paper. This material exhibits the good electrochemical performance. Upon the modification of its surface morphology, the electrochemical performance for Nb18W16O93 nanowire has been greatly improved. Nb18W16O93 nanowire shows the reversible specific capacity of 195 mAh g−1 when the current density is 100 mA g−1 and it can reach 153 mAh g−1 even at 1000 mA g−1. Meanwhile, the lithiation/delithiation mechanism and its corresponding structural change during the charge and discharge process are also carried out by an in-situ XRD technique. The result shows that Nb18W16O93 nanowire has excellent electrochemical reversibility and structural stability. Consequently, Nb18W16O93 nanowire can be employed as a novel anode material for lithium ion batteries.
Hypokinetic dysarthria (HD) occurs in 90% of Parkinson’s disease (PD) patients. It manifests specifically in the areas of articulation, phonation, prosody, speech fluency, and faciokinesis. We aimed to systematically review papers on HD in PD with a special focus on (1) early PD diagnosis and monitoring of the disease progression using acoustic voice and speech analysis, and (2) functional imaging studies exploring neural correlates of HD in PD, and (3) clinical studies using acoustic analysis to evaluate effects of dopaminergic medication and brain stimulation. A systematic literature search of articles written in English before March 2016 was conducted in the Web of Science, PubMed, SpringerLink, and IEEE Xplore databases using and combining specific relevant keywords. Articles were categorized into three groups: (1) articles focused on neural correlates of HD in PD using functional imaging (n = 13); (2) articles dealing with the acoustic analysis of HD in PD (n = 52); and (3) articles concerning specifically dopaminergic and brain stimulation-related effects as assessed by acoustic analysis (n = 31); the groups were then reviewed. We identified 14 combinations of speech tasks and acoustic features that can be recommended for use in describing the main features of HD in PD. While only a few acoustic parameters correlate with limb motor symptoms and can be partially relieved by dopaminergic medication, HD in PD seems to be mainly related to non-dopaminergic deficits and associated particularly with non-motor symptoms. Future studies should combine non-invasive brain stimulation with voice behavior approaches to achieve the best treatment effects by enhancing auditory-motor integration.
Nowadays, new technologies and breakthroughs in the fields of energy efficiency, alternative fuels and added-value electronics are leading to improved, more environmentally sustainable and green thinking applications. Due to the forecasted rapid increase of volume of air traffic, future aircraft generations have to face enhanced requirements concerning productivity, environmental compatibility and higher operational availability, thus effecting technical, operational and economical aspects of in-flight and on-ground power generation systems, even if air transport is responsible for only about 2% of all anthropogenic CO2 emissions. The trend in new aircraft development is toward “more electric” architectures which is characterized by a higher proportion of electrical systems substituting hydraulically or pneumatically driven components, and, as a result, increasing the amount of electrical power. Fuel cell systems in this context represent a promising solution regarding the enhancement of the energy efficiency for both cruise and ground operations. For several years the Institute of Technical Thermodynamics of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) in Stuttgart and Hamburg has developed fuel cell systems for aircraft applications. The activities of DLR focus on: identification of fuel cell applications in aircraft in which the properties of fuel cell systems, namely high electric efficiency, low emissions and silent operation, are capitalized for the aircraft application; design and modeling of possible and advantageous system designs; theoretical and experimental investigations regarding specific aircraft relevant operating conditions; qualification of airworthy fuel cell systems; set up and full scale testing of fuel cell systems for application in research aircraft.
Objective Subjects were exposed to cumulated partial sleep deprivation (psd), alcohol intake and hypoxia in a sequential design to examine the impact on neurobehavioral performance. Methods Sixteen healthy male volunteers were enrolled in this study and were exposed in turn, after adaptation and baseline measurements, to one day of periods of hypoxia, one day of alcohol intake and one day for recovering (with 8h time in bed TIB). Subsequently the exposition of those conditions is that the subjects spent 5h night restriction daily for four consecutive days, followed by two recovery days. Performance was tested five (or six) times per day with reaction time task (SRT) and unstable tracking task (UTT). Results The performance impairment showed to be cumulative in both tests over the four sleep deprivation days and differed significantly from baseline. Corresponding performance deficits under the influence of the stressors were for SRT: four days psd, 13% O2 concentration and a blood alcohol concentration (BAC) of around 0.4–0.6‰ for UTT: four days psd, 13% O2 concentration and a BAC of around 0.6‰. One night of 8h sleep restored performance nearly to baseline level. Conclusions A sleeping time of 5h per night for four consecutive days impairs performance in such a way that traffic safety may be compromised.
Sodium ion batteries (SIBs) are very promising for large-scale energy storage in virtue of its high energy density, abundant sodium resources and low environmental impact, etc. However, it is still a big challenge to develop high-performance and durable cathode materials for SIBs. Among different candidate materials, Na3V2(PO4)3 has attracted great attentions due to its high theoretical capacity (117 mAh/g), stable framework structure and excellent ionic conductivity. However, Na3V2(PO4)3 delivers inferior rate capability and cycling stability due to its poor electronic conductivity. In this work, free-standing Na3V2(PO4)3/carbon nanofiber membranes are synthesized by an electrospinning-sintering route. The sample could deliver excellent cycling capability with specific capacity of 112 mAh/g at 1 C after 250 cycles and ultrahigh rate capability with 76.9 mAh/g even at 100 C, which is superior to many state-of-the-art SIB cathode materials. This can be attributed to the hierarchically distributed Na3V2(PO4)3 crystals in carbon nanofiber network, which possesses outstanding electronic/ionic conductivity and thus leads to an ultrahigh rate capability.
A new group of room temperature ionic liquids based on triethylalkyl and tri-n-butylalkylphosphonium cations with a bis(trifluoromethylsulfonyl)imide anion as a novel green solvent is presented. The electrochemical behaviors of trivalent, divalent and neutral complexes such as rare earth, noble metal and ferrocene were investigated in phosphonium based ionic liquids in comparison with the corresponding ammonium type of ionic liquids. The diffusion coefficients of these metal complexes were estimated by cyclic voltammetry, chronoamperometry and chronopotentiometry, because it is important for development of the electrochemical devices to understand the available diffusive properties. The redox potentials of these trivalent lanthanide couples suggested that the donor property of phosphonium based ionic liquids was slightly larger than that of nitrogen based ionic liquids. The palladium complexes were more stabilized in phosphonium ionic liquids due to the relatively strong ligand field. The redox reaction of neutral complex, ferrocene, was reversible electrochemically in triethylalkyl and tri-n-butylalkyl phosphonium based ionic liquids. The multivalent and neutral complexes in phosphonium type of ionic liquids were somewhat movable than that in corresponding ammonium ionic liquids because the interaction between the cation and the anion in phosphonium based ionic liquids is weaker.
The layered LiMn1/3Ni1/3Co1/3O2 cathode materials were synthesized by an oxalate co-precipitation method using different starting materials of LiOH, LiNO3, [Mn1/3Ni1/3Co1/3]C2O4·2H2O and [Mn1/3Ni1/3Co1/3]3O4. The morphology, structural and electrochemical behavior were characterized by means of SEM, X-ray diffraction analysis and electrochemical charge–discharge test. The cathode material synthesized by using LiNO3 and [Mn1/3Ni1/3Co1/3]C2O4·2H2O showed higher structural integrity and higher reversible capacity of 178.6mAhg−1 in the voltage range 3.0–4.5V versus Li with constant current density of 40mAg−1 as well as lower irreversible capacity loss of 12.9% at initial cycle. The rate capability of the cathode was strongly influenced by particle size and specific surface area.
A new type of composites, i.e. polymer-in-ceramic (as opposed to the “classical” ceramic-in-polymer approach) was introduced into the field of composite polymeric electrolytes. In this work the preparation of porous ceramic samples based on alumina is designed and their properties are characterised by XRD, porosimetry and SEM. Special setup was developed for the preparation of electrolytes in vacuum/controlled atmosphere conditions and it was used for preparing the composites. The studied systems exhibited excellent mechanical properties, high conductivities and good stability vs. Li metal electrodes under prolonged storage.
Billions of dollars are projected to be spent on restoration projects along the northern Gulf Coast which will require efficient monitoring at both landscape and project-specific scales. Recent developments in unmanned aircraft systems (UAS) have sparked interest in the ability of these “drones” to capture hyperspatial imagery (pixel resolution < 10 cm) that resolves individual species and produces accurate data for monitoring programs in coastal landscapes. We present a case study conducted at Coastwide Reference Monitoring System (CRMS) station 0392, a Spartina patens–dominated, oligohaline coastal marsh in Terrebonne Parish, Louisiana. Results demonstrate the ability of UAS technology to collect hyperspatial, multispectral aerial images in a coastal wetland, and to produce very-high-resolution orthomosaics and digital elevation models. We then used object-based image analysis (OBIA) techniques to (1) delineate the land–water interface, (2) classify composition by dominant species, and (3) quantify average plant height by species. Model results were validated with traditional on-the-ground CRMS vegetation surveys. Results suggest that OBIA methods can overcome the spectral variability of hyperspatial datasets, quantify uncertainties in conventional techniques, and provide improved estimates of wetland vegetation cover and species composition. These methods scale conventional plot-level coverage values to data-rich landscape-level models and provide useful tools to monitor restoration performance, landscape changes, and ecosystem services in coastal wetland systems.
Impedance spectroscopy is a very useful technique as a testing method in analysis of electrochemical systems, material studies, corrosion systems, batteries, etc. However its use in fuel cells has been relatively limited. This work presents impedance results during MEA’s evaluation, when testing conditions are varied in single cells. Contributions of different processes effects on complex plane results are discussed.
A thin-film electrochemical sensor electrode capable of electrolytic conductivity, cyclic voltammetry, and temperature measurements of electrolyte solutions has been fabricated and characterized. The electrode fabrication and calibration is detailed, showing accuracies of ±
There is currently a large effort to increase the energy density of batteries and electrochemical double-layer capacitors (EDLCs) for applications ranging from electronics to powering vehicles. While developing higher voltage and high-capacity electrodes is necessary to increase the energy density of batteries, it is generally accepted that the electrolyte limits the adoption of these new electrodes [1–4]. Similarly, the electrolyte breakdown can limit the maximum voltage and energy density of an electrochemical double-layer capacitor [5–7]. In addition to developing a wider potential electrolyte, the electrolytic conductivity must also be high enough for the device to deliver suitable power. Lastly, the potential window and conductivity of electrolytes over a broad range of temperatures are important parameters in determining the end performance of a device. These measurements are frequently performed separately with different equipments [3, 7–9], however, having a single measurement electrode to measure both the potential window and conductivity without the need for different measurement apparatus would be a useful tool to quickly collect data on a number of electrolyte solutions.
Spray deposited MnO2 thin films onto glass substrate were subjected to a post-deposition heat treatment and the effects of temperature on electrical transport properties were studied in details. The heating and cooling cycles of the samples are reversible after successive heat-treatments in air and vacuum. The films were polycrystalline in structure and the oxygen chemisorption–desorption process was found to play an important role in controlling the electronic properties. Various grain-boundary and energy band parameters were calculated by taking conventional extrinsic semiconductor theory and grain boundary trapping models into account. The samples were non-degenerate n-type semiconductors. The transport properties are interpreted in terms of Seto's model which was proposed for polycrystalline semiconducting films. The inter-crystallite boundaries of the thin films play an important role in the transport properties.