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High temperature lithium-sulfur batteries are seldom investigated due in part to the lack of mechanical robust separators and the more serious parasitic polysulfide shuttle effects at elevated temperature. Here, we for the first time present high performance lithium-sulfur cells that can be cycled at elevated temperature of 100 °C via designing asymmetric functionalized polyimide-based separators using a facile and scalable blade-casting method. In this sandwich configuration, polyimide nonwovens act as electrochemically and mechanically robust skeleton while Super-P nanoparticles coating and poly (ethylene oxide)-integrated-lithium lanthanum zirconium oxide coating render additional functions of immobilizing polysulfides and inhibiting lithium dendrite growth, respectively. By virtue of the multifarious functions of the modified polyimide-based separator, a high specific capacity of 1474.3 mAh g−1 without severe over-charge behavior is also firstly demonstrated at a higher temperature of 100 °C. Additionally, Li-S cells using the modified polyimide -based separator deliver excellent cycling stability (only 0.2% capacity decay cycle−1 on average exceeding 200 cycles at 80 °C) at a relatively high rate of 5C. The experimental results validate the pivotal role of newly designed separators for high performance lithium-sulfur chemistry especially at elevated temperature.
Air cathodes, where oxygen reacts with Li ions and electrons with discharge oxide stored in their pore structure, are often considered as the most challenging component in nonaqueous Lithium-air batteries. In non-aqueous electrolytes, discharge oxides are usually insoluble and hence precipitate at local reaction site, raising the oxygen transport resistance in the pore network. Due to their low electric conductivity, their presence causes electrode passivation. This study aims to investigate the air cathode’s performance through analytically obtaining oxygen profiles, modeling electrode passivation, evaluating the transport polarization raised by discharge oxide precipitate, and developing analytical formulas for insoluble Li oxides storage capacity. The variations of cathode quantities, including oxygen content and temperature, are evaluated and related to a single dimensionless parameter — the Damköhler Number (Da). An approximate model is developed to predict discharge voltage loss, along with validation against two sets of experimental data. Air cathode properties, including tortuosity, surface coverage factor and the Da number, and their effects on the cathode’s capacity of storing Li oxides are formulated and discussed.
We synthesize a carbon anode material with unique nanostructure for high power lithium ion batteries. The carbon material is composed of numerous clusters of carbon nanobeads, and shows a macro-meso-micro hierarchical porous structure. This unique nanostructure appears to facilitate the rapid transfer of lithium ions and a very large ion adsorption. It exhibits a reversible capacity of 407.4mAhg−1 and its rate performance is drastically improved in comparison with that of the commercial graphite. The unique structure enables the anode to combine the advantages of both lithium ion batteries and electrochemical double layer capacitors, resulting in the good electrochemical performance.
The paper introduces a new decision-making process which is used to compare the performance of a ship with either diesel electric hybrid propulsion or conventional propulsion systems. A case study was carried out to compare the performance of both propulsions from cost, environmental and risk perspectives. This paper also overviews the modern approaches of multi-criteria decision-making and highlights some of their shortcomings in particular the fact that these approaches often rely on different criteria such as financial, environmental or risk. This paper aims to overcome this shortcoming by enhancing the process of multi-criteria decision analysis. The key process in this research was to convert all incomparable values into monetary values, thereby enabling the impacts of each criterion to be compared and integrated in a straightforward manner. Results of the case study showed that the use of a hybrid propulsion system could reduce annual operational costs by $ 300,000 (2% total cost) compared with a diesel electric system and almost $ 1 million (7%) compared to a diesel mechanical propulsion system. In order to investigate the optimal use of the hybrid propulsion system, various operational scenarios were identified and applied to the proposed decision-making process. The results showed that operating the ship in hybrid mode during manoeuvring and berthing is more desirable as the holistic cost can reduce in almost $ 1 million. The advantages of the proposed decision making process was illustrated by comparing the results obtained from a conventional decision-making process using the analytical hierarchical method. It is believed that the research findings not only present general understanding of the possible advantages of hybrid propulsion for stakeholders, but provide them with an insight into the enhanced approach into the multi-criteria decision analysis.
Lithium transition-metal oxides Li(Mn2−x Co x )O4 (0≤x≤0.5) are synthesized by solid state reaction. X-ray and electrochemical data show that the replacement of Mn3+ (d4) ions by Co3+ (d6) in the octahedral framework of the spinel eliminates the local disorder present in the lattice around the [Mn3+O6] octahedra. The capacity loss observed in the undoped Li/LiMn2O4 cell is about 25% after 20 cycles, whereas that for the x=0.1 and 0.2 doped spinel materials is about 0.48 and 1%, respectively. The good capacity retention of Li(Mn2−x Co x )O4 (0.1≤x≤0.5) electrode is attributed to the stabilization of the spinel structure by Co doping for Mn ion sites. The chemical substitution of Co3+ for Mn3+ in LiMn2O4 improves the efficiency in maintaining electrochemical capacity over a large number of cycles without sacrificing initial reversible capacity at room temperature.
In this study, biomorphic hard carbon is prepared from corn husk using the one-step carbonization method and used as a potassium-ion battery anode material. The biocarbon anode with extremely small specific surface area (3.4 m2 g−1) demonstrates better electrochemical performance than those with large specific surface areas. Particularly, at a current density of 0.1 A g−1, the carbon electrode delivers first discharge and charge capacities of 396.2 and 231.0 mAh g−1, respectively. After 100 cycles, the reversible capacity retention rate is 89.1%. Moreover, at a high current density of 1 A g−1, the reversible capacity reaches approximately 135.3 mAh g−1 after 500 cycles. This excellent performance is attributed to the enhancement of ion diffusion kinetics because of the hierarchically porous structures, effect of nitrogen and oxygen heteroatoms and rational interlayer spacing of biocarbon materials. In comparison, activated biocarbon exhibits lower reversible capacity, ascribed to the formation of more solid electrolyte interphase and destruction of hierarchical structures via KOH activation. Cyclic voltammetry calculation indicates that both capacitance and diffusion are responsible for the excellent K ion storage.
A 1kW-class electrochemical reactor for hydrogen production was developed using bipolar plates. To fabricate thick, large-area electrodes, a particle electrode fabrication method was also introduced. Scanning electron microscopy with energy dispersive X-ray spectroscopy and galvanostatic performance measurements were performed to evaluate the particle electrodes. The results show that the particle electrodes exhibit an excellent charge performance despite the electrode material layer being relatively thick and highly porous. The electrochemical reactor contained 20 single cells stacked together with 30Ah of nickel hydroxide and 15Ah of metal hydride as the positive and negative electrodes, respectively. The electrochemical tests showed that the stack exhibited a high hydrogen production efficiency with a maximum current efficiency of 95.3% for hydrogen production and a hydrogen evolution amount per unit input electrical energy of 259.1mL/Wh at 0.2C. At high current densities (2.0C), a rapid temperature increase was also observed during the charging process, which led to a reduction of the hydrogen production efficiency. Therefore, further design modifications are needed to control heat generation during operation of the device.
In-situ coating approach using phenolic resin as carbon source is introduced in this work with the aim of getting high rate Li2MnSiO4/C composite. Li2MnSiO4/C nanoparticles, average diameter of ca. 25 nm, are well dispersed and the carbon layers are 3–8 nm in thickness. The composites deliver much higher electrochemical performance than those using sucrose as carbon source, in terms of reversible discharge capacity and cycling performance. High rate performance is also observed. It exhibits high reversible capacities of 181.6, 149.1, 133.5 mAh g−1 at 0.4, 1.2 and 2 C, respectively. At 4 C-rate, the electrode still maintains a discharge capacity of 108.7 mAh g−1, around 52.5% of its capacity at 0.1 C. Apparently, in-situ synthesis of carbon coated Li2MnSiO4 using phenolic resin as carbon source results in thin and homogeneous carbon layer with relatively high sp 2/sp 3 ratio, as well as the limited particle size, which are the main reasons for the superior rate capability.
This study evaluated whether two people with developmental disabilities would be able to actively perform simple occupational activities to control their preferred environmental stimulation using a Nintendo Wii Remote Controller with a newly developed three-dimensional object orientation detection program (TDOODP, i.e. a new software program, which turns a Wii Remote Controller into a three-dimensional object orientation detector). An ABAB design, in which A represented the baseline and B represented intervention phases, was adopted in this study. The data shows that the performance of both participants has significantly increased (i.e. they perform more simple occupational activities to activate the control system to produce environmental stimulation) during the intervention phases. The practical and developmental implications of the findings are discussed.
Ionic liquids (ILs) are a novel class of solvents with interesting physicochemical properties. Many different applications have been reported for ILs as alternatives to organic solvents in chemical and bioprocesses. Despite the argued advantage of having low vapor pressure, even the most hydrophobic ILs show some degree of solubility in water, allowing their dispersion into aquatic systems and raising concerns on its pollutant potential. Moreover, nowadays most widespread notion concerning the ILs toxicity is that there is a direct relationship with their hydrophobicity/lipophilicity. This work aims at enlarging the currently limited knowledge on ILs toxicity by addressing negative impacts in aquatic ecosystems and investigating the possibility of designing hydrophobic ILs of low ecotoxicity, by the manipulation of their chemical structures. The impact of aromaticity on the toxicity of different cations (pyridinium, piperidinium, pyrrolidinium and imidazolium) and hydrophobic anions (bis(trifluoromethylsulfonyl)imide [NTf2] and hexafluorophosphate [PF6]) was analysed. Concomitantly, several imidazolium-based ILs of the type [CnCmCjim][NTf2] were also studied to evaluate the effects of the position of the alkyl chain on the ILs’ toxicity. For that purpose, standard assays were performed using organisms of different trophic levels, Vibrio fischeri, Pseudokirchneriella subcapitata and Daphnia magna, allowing to evaluate the consistency of the structure–activity relationships across different biological targets. The results here reported suggest the possibility of designing ILs with an enhanced hydrophobic character and lower toxicity, by elimination of their aromatic nature.
This paper presents a formal mathematical framework for the use of the morphological matrix in a computerized conceptual design framework. Within the presented framework, the matrix is quantified so that each solution principle is associated with a set of characteristics such as weight, cost, performance, etc. Selection of individual solutions is modeled with decision variables and an optimization problem is formulated. The applications are the conceptual design of subsystems for an Unmanned Aerial Vehicle and an aircraft fuel transfer system. Both the system models and the mathematical framework are implemented in MS Excel.
The electrochemical properties of a solid hybrid polymer electrolyte for lithium batteries based upon tri-ethyl sulfonium bis(trifluorosulfonyl) imide (S2TFSI), lithium TFSI, and poly(ethylene oxide) (PEO) is presented. We have synthesized homogenous freestanding films that possess low temperature ionic conductivity and wide electrochemical stability. The hybrid electrolyte has demonstrated ionic conductivity of 0.117mScm−1 at 0°C, and 1.20mS cm−1 at 25°C. At slightly elevated temperature ionic conductivity is on the order of 10mScm−1. The hybrid electrolyte has demonstrated reversible stability against metallic lithium at the anodic interface and >4.5V vs. Li/Li+ at the cathodic interface.
LiFePO4, olivine-type LiFe0.9Mn0.1PO4/Fe2P composite was synthesized by mechanical alloying of carbon (acetylene back), M2O3 (M=Fe, Mn) and LiOH·H2O for 2h followed by a short-time firing at 900°C for only 30min. By varying the carbon excess different amounts of Fe2P second phase was achieved. The short firing time prevented grain growth, improving the high-rate charge/discharge capacity. The electrochemical performance was tested at various C/x-rate. The discharge capacity at 1C rate was increased up to 120mAhg−1 for the LiFe0.9Mn0.1PO4/Fe2P composite, while that of the unsubstituted LiFePO4/Fe2P and LiFePO4 showed only 110 and 60mAhg−1, respectively. Electronic conductivity and ionic diffusion constant were measured. The LiFe0.9Mn0.1PO4/Fe2P composite showed higher conductivity and the highest diffusion coefficient (3.90×10−14 cm2 s−1). Thus the improvement of the electrochemical performance can be attributed to (1) higher electronic conductivity by the formation of conductive Fe2P together with (2) an increase of Li+ ion mobility obtained by the substitution of Mn2+ for Fe2+.
An automatic prototype aerosol sampler has been specifically revised to gain reliable year round data sets of the chemical aerosol composition at high Alpine ice core drill sites. An unattended deployment of the new aerosol sampler at the Vallot Observatory (4361ma.s.l., French Alps) showed that previous shortcoming such as sensitivity to lightning activities and strong passive sampling effects were successfully overcome. The latter effect was almost eliminated, leading to an improvement of the detection limits by up to a factor of 30. Detailed investigations of the blank variability and sampling characteristics revealed that the new sampler allows to quantify the aerosol species NH4 +, SO4 2−, K+, oxalate as well as total Cl− and total NO3 −. In addition records of Na+, Mg2+ and Ca2+ can be provided though systematically underestimated. On the other hand unreliable results are derived for formate, acetate and SO2. Considering a bi-weekly sampling interval, detection limits range from 0.2 to 2ngm−3 STP (except for Na+: 16ngm−3 STP). Such a detection limit is also accessible for Na+ if PTFE filters are used. The aerosol data set gained at Vallot Observatory allowed preliminary estimates of mean firn/air ratios for NH4 +, SO4 2− and total NO3 −. The air/firn relationship appeared to be consistent compared to other high elevation ice core drilling sites. With the improved detection limits at still minimized energy consumption, a year round deployment of the automatic aerosol sampler appears now to be feasible even at polar glacier sites.
Epigenetics is the study of mitotically or meiotically heritable changes in gene function that occur without a change in the DNA sequence. Interestingly, epigenetic changes can be triggered by environmental factors. Environmental exposure to e.g. metals, persistent organic pollutants or endocrine disrupting chemicals has been shown to modulate epigenetic marks, not only in mammalian cells or rodents, but also in environmentally relevant species such as fish or water fleas. The associated changes in gene expression often lead to modifications in the affected organism’s phenotype. Epigenetic changes can in some cases be transferred to subsequent generations, even when these generations are no longer exposed to the external factor which induced the epigenetic change, as observed in a study with fungicide exposed rats. The possibility of this phenomenon in other species was demonstrated in water fleas exposed to the epigenetic drug 5-azacytidine. This way, populations can experience the effects of their ancestors’ exposure to chemicals, which has implications for environmental risk assessment. More basic research is needed to assess the potential phenotypic and population-level effects of epigenetic modifications in different species and to evaluate the persistence of chemical exposure-induced epigenetic effects in multiple subsequent generations.
We demonstrate a novel rechargeable energy storage system having a metallic lithium negative electrode and a liquid–solid hybrid positive electrode of Fe3+/Fe2+/Fe in N,N-Dimethylformamide, which are separated by an impermeable NASICON–type Li1.4Al0.4Ge0.2Ti1.4(PO4)3–epoxy resin composite film with a lithium ion conductivity of ca. 5.0 × 10−4 S cm−1. The discharge curve for the battery shows two plateaus. The first plateau corresponds to Li + FeCl3 = LiCl + FeCl2, while the second one is associated with 2 Li + FeCl2 = 2 LiCl + Fe. In the process of reduction of Fe3+ to Fe2+, it delivers a stable discharge capacity of ca. 110 mAh gFeCl3 −1 with a Coulombic efficiency higher than 95% and is capable of enduring over 60 circles at a high current density of 1.0 mA cm−2 without any catalyst. Furthermore, a stable discharge capacity up to ca. 455 mAh gFeCl3 −1 is achieved for conversion of FeCl3/FeCl2/Fe with a three–electron reaction. This work demonstrates a proof of feasibility of hybrid liquid–solid hybrid positive electrode, since these reactions are reversible confirmed by x–ray diffraction patterns and EDX mapping test.
Garnet electrolytes having a room-temperature Li+ conductivity of 10−3 S cm−1 suffer from adsorbents that prevent wetting by a lithium anode; formation and growth of lithium-anode dendrites into grain boundaries and a huge interfacial resistance to anode plating and stripping result. A thin coating of a garnet surface by a Li+-conducting polymer with a transfer number of 0.9 is shown to suppress dendrite formation and to reduce greatly the interfacial resistance. A coulombic efficiency near 100% with a single thin polymer coat can provide Li/garnet/LiFePO4 all-solid-state cell with a long cycle life.
Gallium oxide nanorods prepared by template-free synthesis are reported for the first time as safe and durable anode material for lithium- and sodium-ion batteries. The ambient temperature electrochemical response of the nanorods, tested by cyclic voltammetry and constant-current reversible cycling, is highly satisfying in terms of remarkable stability and capacity retention upon long-term operation (400 cycles), even at high current densities. The newly proposed application of gallium oxide nanorods as electrode material is notable also because this material can preserve the electrical pathway without the need of any “buffer matrix” to compensate for the expansion upon lithium or sodium reversible storage. The highly promising electrochemical performance is attributed to the high aspect ratio and high surface area that stem from the nanorod morphology and which can lead to short diffusion path and fast kinetics of both cations (Li+ or Na+) and electrons.
Lucid dreaming, in which the sleeper is aware of the dream state, has been associated with increased neural activity around 40 Hz (lower gamma band), but their causal relationship remains unclear. The authors show that, during REM sleep, fronto-temporal transcranial stimulation in the lower gamma band can induce lucid dreaming.
Nitrogen-doped porous interconnected double-shelled hollow carbon spheres (N-DHCSs) have been synthesized by chemical treatment of Fe3O4@C precursors using HNO3 at low temperature. When the precursors are disposed with HCl or H2SO4, uniform porous interconnected double-shelled hollow carbon spheres (DHCSs) are prepared. Comparing with DHCSs, the as-prepared N-DHCSs show higher Li-storage capacity and both show good cycling stability as anode materials in lithium ion batteries. The N-DHCSs offer a capacity of 512mAhg−1 at 1.5C after 500 cycles and their porous interconnected double-shelled hollow structure could be well kept. The N-DHCSs also show high reversible capacity of 598mAhg−1 at 1C after cycled at different current densities. In addition, the N-DHCSs as anode materials in sodium half-cell exhibit high reversible capacity of 120mAhg−1 at a current rate of 0.2Ag−1 after 100 cycles.
The field of forensic genetics has made great strides in the analysis of biological evidence related to criminal and civil matters. More so, the discipline has set a standard of performance and quality in the forensic sciences. The advent of massively parallel sequencing will allow the field to expand its capabilities substantially. This review describes the salient features of massively parallel sequencing and how it can impact forensic genetics. The features of this technology offer increased number and types of genetic markers that can be analyzed, higher throughput of samples, and the capability of targeting different organisms, all by one unifying methodology. While there are many applications, three are described where massively parallel sequencing will have immediate impact: molecular autopsy, microbial forensics and differentiation of monozygotic twins. The intent of this review is to expose the forensic science community to the potential enhancements that have or are soon to arrive and demonstrate the continued expansion the field of forensic genetics and its service in the investigation of legal matters.
Capacity intermittent titration technique (CITT) was used to investigate the chemical diffusion coefficient ( D ˜ ) of lithium-ion in LiFePO4 cathode material. The values of D ˜ at the galvano-charge current of 0.2 and 0.4mA were respectively found to range from 8.8×10−16 to 8.9×10−14 cm2 s−1 and from 1.2×10−16 to 8.5×10−14 cm2 s−1 in the voltage range from 3.2 to 4V (vs. Li+/Li). The transfer coefficients of cathode (0.32–0.42) and anodic (0.26–0.3), and the standard rate constant (1.58×10−9 to 1.30×10−8 cms−1) were measured from the Tafel plots of LiFePO4 in the equilibrium potential range from 3.06 to 3.45V. From these kinetic parameters, the finite kinetics at interface was taken into account to revise the above values of D ˜ . The revised values of D ˜ at the galvano-charge current of 0.2 and 0.4mA were respectively found to range from 2.44×10−15 to 2.21×10−13 cm2 s−1 and from 5.81×10−16 to 3.22×10−13 cm2 s−1 in the voltage range from 3.2 to 4V. Results show that the approximation of infinite charge-transfer kinetics leads to a spurious value of D ˜ which is lower than the revised value, and the spurious extent depends on the galvano-charge current of CITT experiment.