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The objective of this work was to demonstrate a micro-fabricated hydrogen storage module for micro-power systems. Hydrogen storage materials were developed as thin-film inks to be compatible with an integrated manufacturing process. Performance and durability of storage modules were evaluated. Further, applications were demonstrated for a nickel–hydrogen battery and a micro-fabricated hydrogen–air PEM fuel cell. The ink making process, in which polymer binders and solvents were added to the palladium-treated alloys, slightly decreased the storage capacities, but had little effect on the activation properties of the treated alloys. After 5000 absorption/desorption cycles under hydrogen, the hydrogen storage capacities of the thin-film inks remained high. Absorption/desorption behavior of the ink was tested in the environment of a new type nickel–hydrogen battery, in which it would in contact with 26wt% KOH solution, and the ink showed no apparent degradation. Storage modules were successfully used as the hydrogen source for PEM fuel cell.
Background Cognitive dysfunction is common in psychotic disorders, and may reflect underlying pathophysiology. However, substantial cognitive heterogeneity exists both within and between diagnostic categories, creating challenges for studying the neurobiology of cognitive dysfunction in patients. The aim of this study was to identify patients with psychosis with intact versus impaired cognitive profiles, and to examine resting state functional connectivity between patient groups and compared to healthy controls to determine the extent to which patterns of connectivity are overlapping or distinct. Methods Participants with affective or non-affective psychosis (n =120) and healthy controls (n =31) were administered the MATRICS Consensus Cognitive Battery, clinical and community functioning assessments, and an fMRI scan to measure resting state functional connectivity (RSFC). Cognitive composite scores were used to identify groups of patients with and without cognitive dysfunction. RSFC was compared between groups of patients and healthy controls, controlling for demographic and clinical variables. Results Both cognitively intact and cognitively impaired patients showed decreased intrinsic connectivity compared to controls in frontoparietal control (FPN) and motor networks. Patients with cognitive impairment showed additional reductions in FPN connectivity compared to patients with intact cognition, particularly in subnetwork A. Conclusions We leveraged the heterogeneity in cognitive ability among patients with psychosis to disentangle the relative contributions of cognitive dysfunction and presence of an underlying psychotic illness using resting state functional connectivity. These findings suggest at least partially separable effects of presence of a psychotic disorder and neurocognitive impairment contributing to network dysconnectivity in psychosis.
This paper discusses the preparation of microporous fibrous membranes from PVdF solutions with different polymer contents, using the electrospinning technique. Electrospun PVdF-based fibrous membranes with average fiber diameters (AFD's) of 0.45–1.38μm have an apparent porosity and a mean pore size (MPS) of 80–89% and 1.1–4.3μm, respectively. They exhibited a high uptake of the electrolyte solution (320–350%) and a high ionic conductivity of above 1 × 10−3 s/cm at room temperature. Their ionic conductivity increased with the decrease in the AFD of the fibrous membrane due to its high electrolyte uptake. The interaction between the electrolyte molecules and the PVdF with a high crystalline content may have had a minor effect on the lithium ion transfer in the fibrous polymer electrolyte, unlike in a nanoporous gel polymer electrolyte. The fibrous polymer electrolyte that contained a 1M LiPF6-EC/DMC/DEC (1/1/1 by weight) solution showed a high electrochemical stability of above 5.0V, which increased with the decrease in the AFD The interfacial resistance (R i) between the polymer electrolyte and the lithium electrode slightly increased with the storage time, compared with the higher increase in the interfacial resistance of other gel polymer electrolytes. The prototype cell (MCMB/PVdF-based fibrous electrolyte/LiCoO2) showed a very stable charge–discharge behavior with a slight capacity loss under constant current and voltage conditions at the C/2-rate of 20 and 60°C.
Manganese based precious metal-free electrocatalysts for the oxygen evolution reaction (OER) are promising materials for energy storage systems based on dark or photo-coupled water electrolysis, because they are active, inexpensive and of low toxicity. In this work, atomic scale structure–activity relationships of two different nano-structured manganese oxides, MnOx, are established using a combination of X-ray absorption, diffraction and electrochemistry. Prepared by chemical symproportionation (s-MnOx) and impregnation (i-MnOx), the s-MnOx catalyst consisted of a layered structure similar to δ-MnO2 while the i-MnOx catalyst displayed a mixture of tunnelled, 3D cross-linked β- and defective γ-MnO2 structures. During electrocatalytic oxygen evolution the structural motifs of both MnOx remain largely unchanged, but the oxidation state of Mn increases from 3.5 to 3.9–4. Kinetic parameters of the electrocatalytic oxygen evolution reaction were extracted using Tafel slope analysis and pH titration experiment, and the role of the protons abstracted was analyzed. The study reveals fundamental differences of general importance in the catalytic activity between layered and cross-linked structures. The exclusive presence of di-μ-oxo-bridged Mn ions in the layered structure is coupled to a pronounced redox and charge capacity behaviour. This ensured efficient use of surface and bulk active sites, and resulted in a relatively large Tafel slope. Consequently, the intrinsic OER activity is especially high in s-MnOx. In contrast, 3D cross-linked structures with both mono- and di-μ-oxo-bridged Mn ions resulted in lower intrinsic activity but smaller Tafel slope, and thus favourable activity at technological water-splitting rates. The insights from this comparative study will provide guidance in the structural design and optimization of other non precious metal oxide OER catalysts.
Transition metal oxides have high theoretical capacities when served as anode for lithium-ion battery but suffer poor cyclability and high rate capacity due to large volumetric changes and low ions diffusion kinetics. To issue these problems, we introduce hierarchical porous structure into CoO x /carbon nanocomposite through constructing SiO2-CoO x -phenolic-resin gel coupled with subsequent high temperature annealing and removing SiO2 template. In this nanocomposite, Co3O4 and Co nanoparticles with the size of about 10nm uniformly disperse in the hierarchical porous carbon matrix. The hierarchical porous structure can provide multistage transfer channels for lithium-ions, which enhances the lithium-ion diffusion kinetics in CoO x nanoparticles. Meanwhile the hierarchical porous structure can accommodate volumetric changes of CoO x nanoparticles during electrochemical cycling, which assure the electrode integrity. The carbon matrix and metal Co nanoparticles are able to provide rapid transfer channels for electrons. Therefore, the hierarchical porous CoO x /carbon nanocomposite electrode delivers excellent cyclability and high-rate capacities. The reversible capacities remain 381mAh g−1 after 500cycles at 1.0A g−1, and 298mAh g−1 after 1000cycles at 5.0A g−1. The reversible capacity at 20A g−1 remains 195mAh g−1, which is 25.6% of that at 0.2A g−1. The full battery using the hierarchical porous CoO x /C nanocomposite as the negative electrode and lithium nickel cobalt manganese oxide as the positive electrode delivers first energy density of 151mWh g−1 based on the whole mass of negative/positive electrodes. This work provides a possible pathway to achieve promising electrode materials for lithium-ion batteries.
A novel ultrasonic peening technique was developed to obtain a special copper foil with microcrystalline morphology surface. The obtained microcrystalline Cu-graphite electrode displays better conductivity, higher bonding strength with graphite particles, and stronger corrosion resistance to the electrolyte than the pristine copper foil, which lead to its superior lithium storage performance. The initial charging capacities of Cu-graphite/Li electrodes with ultrasonic peening times of 9 s and 15 s are as high as 312.4 and 359.5 mAh g−1, respectively, which are much higher than those of a pristine Cu-graphite electrode (282.3 mAh g−1). After 380 cycles, the discharging capacities remain at 239.0 and 332.8 mAh g−1 with capacity retentions of 76.5% and 92.6%, respectively, which are also much higher than those of the pristine Cu-graphite electrode (187.6 mAh g−1 and 66.4% after 270 cycles, respectively). After ultrasonic peening on the copper foil surface, the capacity, cycling and rate performance of the Cu-graphite electrode are greatly improved in both a Cu-graphite/Li half battery and an LiNi0.8Co0.1Mn0.1/Cu-graphite full battery, which would providing a new idea for the development of large-capacity and long-life electrode collector materials for lithium-ion batteries.
Lithium–sulfur batteries are promising next-generation energy storage devices due to their high energy density and low material cost. Efficient conversion of lithium polysulfides to lithium sulfide (during discharge) and to sulfur (during recharge) is a performance-determining factor for lithium–sulfur batteries. Here we show that MoS2−x/reduced graphene oxide (MoS2−x/rGO) can be used to catalyze the polysulfide reactions to improve the battery performance. It was confirmed, through microstructural characterization of the materials, that sulfur deficiencies on the surface participated in the polysulfide reactions and significantly enhanced the polysulfide conversion kinetics. The fast conversion of soluble polysulfides decreased their accumulation in the sulfur cathode and their loss from the cathode by diffusion. Hence in the presence of a small amount of MoS2−x/rGO (4 wt% of the cathode mass), high rate (8C) performance of the sulfur cathode was improved from a capacity of 161.1 mA h g−1 to 826.5 mA h g−1. In addition, MoS2−x/rGO also enhanced the cycle stability of the sulfur cathode from a capacity fade rate of 0.373% per cycle (over 150 cycles) to 0.083% per cycle (over 600 cycles) at a typical 0.5C rate. These results provide direct experimental evidence for the catalytic role of MoS2−x/rGO in promoting the polysulfide conversion kinetics in the sulfur cathode.
A new nano-sized lead(II) one-dimensional coordination polymer with Pb⋯F interactions, [Pb(μ-TFPB)2] n (1) [TFPB− =4,4,4-trifluoro-1-phenyl-1,3-butandionate], has been synthesized and characterized by SEM, X-ray powder diffraction, IR spectroscopy and elemental analyses. The single-crystal X-ray data of compound 1 show that the Pb(II) atoms have a hemidirected coordination sphere with an environment of PbO6F2. The presence of a stereo-chemically active lone pair of the lead atom is apparently the reason that the neighboring bridging bond relative to gap of coordination sphere are so long. Therefore arrangement of “TFPB−” ligands suggests a gap or hole in coordination geometry around the lead(II) ions. PbO nanoparticles were obtained by calcination of the nano-sized compound 1 at 600°C.
As an electrochemical component, a lithium-ion battery is clearly a multi-disciplinary system. The choice was made to model it via Bond Graph formalism. Although this tool has been developed since the 1970s, the novelty is its application to lithium-ion batteries, which turns the modeling presented here into an original energy approach. The main objective is to develop and validate a lithium-ion battery model that could be implemented in a global system for energy monitoring. However, nearly every phenomenon occurring in the battery is taken into account for a possible ageing or thermal study. In the first part, the energy modeling approach is described. In the second part, the lithium-ion battery operation is explained. In the third part, the Bond Graph model is proposed. At last, experimental validations are presented.
High aspect ratio, electrospun CuO nanofibers have been fabricated and tested for its electrochemical performance as lithium ion battery anode. These nanofibers are composed of CuO nanoparticles about 35–40 nm in size forming good inter-connected network. Fabricated half cells maintained specific capacity of 310 mAh g−1 at 1C rate for 100 cycles and stabilized capacity of about 120 mAh g−1 at 5C rate for 1000 cycles. Ex situ x-ray photoelectron spectroscopy (XPS) was performed to understand the electrodes surface chemical changes at the end of first discharge, first charge and after tenth charge. The solid electrolyte interface (SEI) layer comprised of LiF, Li2CO3 and Li2O while their quantity varied depending on the stage of lithiation/delithiation. Initially, no copper signal is observed on the surface of the SEI layer. However, in situ sputtering of the electrodes in the XPS chamber revealed that at the end of first discharge, formation Cu0 with detectable fraction of LixCuO2 and hydroxide in the SEI layer. At the end of first charge, a large fraction of Cu2O phase with a small fraction of hydroxide is observed. At the end of 10th charge no change in SEI layer content but increase in thickness was observed.
Manganese oxide was prepared by an irradiation of ultrasound to an acetone solution of potassium permanganate. The chemical analyses of gas, solution and products have shown that the synthetic reaction was not peculiar to sonochemistry but similar to the reaction in the basic aqueous solution. The product contained manganese oxide and by-products such as acetate and oxalate. Those by-products were difficult to be removed thoroughly and a part of them resided even after wash. From XRD, the obtained manganese oxide was likely to be α-MnO2. The product was examined as electrode material of lithium ion battery, and showed 180mAhg−1 of specific capacity under 0.5Ag−1 of current density. Moreover, it could be discharged and charged under a high level of current density (ca. 100mAhg−1 at 17C). The capacity deterioration caused by cycle repetition was also found to be much small.
The xLiMn0.9Fe0.1PO4·yLi3V2(PO4)3/C (x:y=1:0, 9:1 5:1, 3:1, 1:1 and 0:1) cathode materials are synthesized by a ball–milling and post–calcination method. XRD results reveal that the xLiMn0.9Fe0.1PO4 · yLi3V2(PO4)3/C (x,y≠0) composites are composed of LiMn0.9Fe0.1PO4 and Li3V2(PO4)3 phases, and no impurities are detected. In LiMn0.9Fe0.1PO4–Li3V2(PO4)3 system, most of the manganese, iron and vanadium elements in the raw materials tend to form the two major phases, and only small amounts of V, Mn and Fe as dopants enter into the lattice of LiMn0.9Fe0.1PO4 and Li3V2(PO4)3. Electrochemical tests show that the xLiMn0.9Fe0.1PO4 · yLi3V2(PO4)3/C (x,y≠0) composites exhibit much better performance than the single LiMn0.9Fe0.1PO4/C. Among the samples, 5LiMn0.9Fe0.1PO4 ·Li3V2(PO4)3/C shows the best electrochemical performance. The sample delivers the specific capacities of 158.1, 140.7 and 100.2 mAh g−1 at 0.05, 1 and 4C rates in the potential range of 2.5–4.5V, and exhibits very long and flat discharge plateau around 4.0V up to 1C rate. The sample also shows good cycling performance at various C–rates.
Three-electrolyte configuration with two oppositely charged ion-exchange membranes can be used to yield various promising pH differential power sources. pH change, ion transport and potential profiles across the membranes and electrode/electrolyte interfaces of a three-electrolyte pH differential lead dioxide-metal hydride system are therefore systematically investigated for the first time. We find that i) pH changes of the acid and alkaline chambers are dependent on the combined effect of the electrode reaction and the ion transport. In addition, the pH change of the middle chamber is also affected by the crossover of protons from acid chamber if the anion-exchange membrane has a low permselectivity; ii) the electrical potential gradient mainly controls the ion transport with current flows; iii) the high overall cell voltage is attributed to the large pH acid-alkaline, while the potential across the membranes and electrode/electrolyte interfaces is affected by both pH and the concentration gradient. Key issues and proposed solutions are discussed to improve the electrochemical performance of this three-electrolyte pH differential electrochemical system. This work offers new opportunities to develop promising energy storage technologies.
A major challenge facing those with late stage osteoarthritis is delayed surgery due to waiting lists. In South Africa patients wait years for a hip/knee arthroplasty. Affected patients require effective management to address their pain, especially while awaiting surgery. Existing literature is mostly available from high income countries exploring effects of interventions during short waiting periods. Research is warranted in low income countries where long waiting periods are common. This study explored the effects of a six-week physiotherapist-led exercise and education intervention on pain in this population.
The Co3O4/Co3V2O8/Ni nanocomposites were rationally designed and prepared by a two-step hydrothermal synthesis and subsequent annealing treatment. The one-dimensional (1D) Co3O4 nanowire arrays directly grew on Ni foam, whereas the 1D Co3V2O8 nanowires adhered to parts of Co3O4 nanowires. Most of the hybrid nanowires were inlayed with each other, forming a 3D hybrid nanowires network. As a result, the discharge capacity of Co3O4/Co3V2O8/Ni nanocomposites could reach 1201.8mAh/g after 100 cycles at 100mA/g. After 600 cycles at 1A/g, the discharge capacity was maintained at 828.1mAh/g. Moreover, even though the charge/discharge rates were increased to 10A/g, it rendered reversible capacity of 491.2mAh/g. The superior electrochemical properties of nanocomposites were probably ascribed to their unique 3D architecture and the synergistic effects of two active materials. Therefore, such Co3O4/Co3V2O8/Ni nanocomposites could potentially be used as anode materials for high-performance Li-ion batteries.
Preparation by electrocrystallisation has been carried out for the salts [Rb(anti-dchyl-18c6)]2[Ni(dmit)2] 1, [Rb(anti-dchyl-18c6)][Ni(dmit)2] 2, [Cs(anti-dchyl-18c6)]2[Ni(dmit)2] 3 and [Cs(anti-dchyl-18c6)1.5][Ni(dmit)2]64 (anti-dchyl-18c6 = cis-anti-cis-dicyclohexyl-18-crown-6, dmit = C3S5). Salts 1 and 3 involve the planar dianionic nickel complex sandwiched by two metal–crown units. This leads to short Rb+⋯Ni and Rb+⋯S interactions in 1 and the shortest recorded Cs+⋯Ni distance of 3.47 Å in 3, presumably stabilised by the four surrounding S atoms at 3.73–4.44 Å. DFT calculations on the dianionic salts 1 and 3 indicate an essentially electrostatic interaction between the [Ni(dmit)2]2− complex and the Rb+ or Cs+ ion and show frontier orbitals qualitatively similar to those previously derived from EHMO calculations on molecular conductors containing [Ni(dmit)2]. Salt 2 consists of non-stacked nickel complexes arranged in chains linked by S⋯Rb+ interactions through the terminal sulfurs with the Rb+ ion placed exactly within the plane of the crown oxygens. Magnetic susceptibility measurement indicated weak antiferromagnetic interactions. Salt 4 shows a 2-D sheet of nickel complexes stacked in a herringbone arrangement separated by layers of counter ions complexed by the crowns in a disordered manner with the anion ∶ cation ratio of 6 ∶ 1 uniquely high among [Ni(dmit)2]x− salts. Salt 4 displays semiconductor behaviour with σRT = 10−2 S cm−1.
Winters-Stone KM, Torgrimson B, Horak F, Eisner A, Nail L, Leo MC, Chui S, Luoh S-W. Identifying factors associated with falls in postmenopausal breast cancer survivors: a multi-disciplinary approach. Objective To identify neuromuscular, balance, and vision factors that contribute to falls in recently treated breast cancer survivors (BCS) and explore links between fall risk factors and cancer treatment. Design Case-control plus prospective observation. Setting Comprehensive cancer center. Participants BCS (N=59; mean age, 58y) within 2 years of chemotherapy completion and/or on adjuvant endocrine therapy. Interventions Not applicable. Main Outcome Measures Objective measures of postural control, vision, and neuromuscular function included: (1) a sensory organization test (SOT), (2) a visual assessment battery, (3) muscle mass by dual energy x-ray absorptiometry, and (4) neuromuscular function with strength by repetition maximum, power by timed stair climb, and gait speed by 4m walk. Falls were self-reported for the past year (retrospective) and monthly for 6 months (prospective). Results Fifty eight percent of BCS reported falls in the past year. BCS with a history of falls had lower SOT scores with a vestibular deficit pattern in postural control (P<.01) and took longer to read letters on the contrast sensitivity chart (P<.05). Vestibular score on the SOT mediated the relationship between treatment and falls among BCS who received chemotherapy only, but not adjuvant endocrine therapy. Conclusions Results of this project suggest that balance disturbances of vestibular origin and delays in detecting low contrast visual stimuli are associated with falls in BCS. Future studies that track falls and fall risk factors in BCS from diagnosis through treatment are warranted, as are studies that can identify treatment-related vestibular dysfunction and altered visual processing.
The Al/Pb–0.8%Ag and Al/Pb–0.75%Ag–0.03%Co (in mass fraction) anodes used in zinc electrowinning are prepared through the electrodeposition of lead methanesulfonate electrolyte onto an aluminum matrix. The results of anode polarization curves, Tafel curves, and EIS characterizations indicated that the Al/Pb–0.75%Ag–0.03%Co anode has higher electrocatalytic activity and corrosion resistance than the Al/Pb–0.8%Ag anode. SEM observations on the fruit surfaces demonstrated the crystals on the Al/Pb–0.8%Ag anode are larger than on the Al/Pb–0.75%Ag–0.03%Co anode. After 24 h of anodic polarization, SEM observations and XRD analysis showed that the MnO2–PbO2 layer on the Al/Pb–0.75%Ag–0.03%Co anode surface is characterized by dendritic crystals, and the PbSO4–PbO2 layer under the MnO2–PbO2 layer is characterized by uniform and chaotic orientation tetragonal symmetry crystallites of PbSO4. However, the MnO2–PbO2 layer on the Al/Pb–0.8%Ag anode surface is characterized by granular crystals, and the PbSO4–PbO2 layer under the MnO2–PbO2 layer is characterized by well-organized orientation crystallites of PbSO4, which are concentrated in certain zones.
Studies on the effects of an electromagnetic field on the activity of recombinant luciferase in the luciferase–luciferin–ATP-Mg2+ system were conducted. The enzymatic activity was evaluated by the measurements of biochemiluminescence intensity with a standard chemiluminometer. Frequencies that effectively caused irreversible changes in the enzyme activity were identified. The intensity of chemiluminescence (Icl), after it reached the stationary level, and the time constant of the intensity decay, after cessation of the stationary luminescence due to ATP depletion, were the criteria of the luciferase activity. I0 sharply increased from (250 ± 47) imp/s to (1250 ± 75) imp/s compared to the control under exposure to an electromagnetic field of 6 Hz. At the same time, the duration of the stationary luminescence decreased by approximately five times (from 30 to 5.5 min). The decay of luminescence, τ, accelerated significantly (by nine times relative to the control). An opposite effect of other experimentally chosen frequencies of the electromagnetic field was obtained. As an example, upon exposure to the electromagnetic field with frequencies of 12, 48, and 96 Hz, the luciferase activity decreased by 2 times (at 48 and 96 Hz) and by 4 times (at 12 Hz) compared to the control. Luciferase activity did not differ from the control after exposure to a field of 24 Hz.