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1.
ObjectivesThe study investigated effects of electrode material, inter-electrode distance (IED), and conductive gel on electromyographic (EMG) activity recorded from the masseter muscle.Materials and methodsEMG was recorded unilaterally, as ten volunteers performed standardized oral tasks. Ag/AgCl and Ag coated with Au were the gel-based; Ag alloy coated with graphene, pure Ag coated with graphene and silver nanowire embedded electrodes were the gel-free materials tested. Ag/AgCl electrodes were tested at three different IEDs (i.e. 15 mm, 20 mm, 25 mm). An electrode relative performance index (ERPI) was defined and calculated for each of the standardized oral tasks that the volunteers performed. ERPI values obtained for the different oral tasks with different electrode materials and IEDs were compared using two-way repeated-measures ANOVA.ResultsERPI values were not significantly influenced by IED. However, for the electrode materials statistically significant differences were found in ERPI values for all oral tasks. Of the gel-free electrode materials tested, pure silver electrodes coated with graphene had the highest ERPI values followed by Ag alloy electrodes coated with graphene and silver nanowire embedded electrodes.ConclusionsWithin the limitations of the study, IED between 15 and 25 mm has a negligible effect on masseter muscle EMG. Graphene coated and silver nanowire embedded electrodes show promise as gel-free alternatives.  相似文献   

2.
Properties of hole transporting layers (HTLs) and back electrode are very critical to the stability of inverted bulk heterojunction organic photovoltaic (OPV) modules. Here, various deposition methods for back electrodes and materials of HTLs are examined by applying to inverted organic solar cells with a structure of indium tin oxide/ZnO/photoactive layer/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Ag. The experiment is performed on encapsulated modules with flexible barrier films under accelerated conditions. The OPV modules with screen‐printed Ag electrodes are shown to be electrically unstable with a reduction of the current density under damp heat condition at 85 °C/85% RH. Optical images for the active layer/PEDOT:PSS interface reveal that a reaction between the solvent from the Ag electrode and the underlying layers is the major cause for the degradation. In comparison with materials of the HTLs, the PEDOT:PSS layer shows low stability compared to the MoO3 layer under the accelerated conditions. Unusual chemical changes in the PEDOT:PSS film are observed through X‐ray photoelectron spectroscopy and this is further addressed by correlating the stability of the OPV devices.  相似文献   

3.
Colloidal silver has been known to have unique antimicrobial activity that may be useful in the construction of antibacterial materials (self-cleaning materials) to aid in the fight against bacteria-related infections. In this study, silver-coated TiO2 (Ag/TiO2) particles prepared through the photo-reduction of Ag+ were investigated as an antibacterial agent against Escherichia coli and Staphylococcus aureus. The deposition of Ag onto the surface was confirmed with SEM and EDS analysis of the post-reaction particles. It was also determined that the initial concentration of Ag+ in solution played a significant role in the effective size of the post-irradiation particles. The antibacterial effectiveness of the Ag/TiO2 was evaluated through the determination of the minimum inhibitory concentration (MIC) of AgTiO2 for each species of bacteria. The MIC values for the Ag/TiO2, on both E. coli and S. aureus, were much lower than the MIC values for Ag metal, and quite comparable to the MIC values for AgNO3. A disc diffusion/antibiotic sensitivity test was also performed using the Ag/TiO2 particles and the results compared with the results obtained for Ag metal, AgNO3 and common antibacterial agents; tetracycline, chloramphenicol, erythromycin, and neomycin. The zone of inhibition diameters for the Ag/TiO2 particles were found to be comparable with those of the other antimicrobial agents.  相似文献   

4.
Supercapacitors (SCs) have great promise as the state‐of‐the‐art power source in portable electronics and hybrid vehicles. The performance of SCs is largely determined by the properties of the electrode material, and numerous efforts have been devoted to the explorations of novel electrode materials. Recently, iron‐based materials, including Fe2O3, Fe3O4, FeOOH, FeOx, CoFe2O4, and MnFe2O4, have received considerable attention as very promising electrode materials for SCs due to their high theoretical specific capacitances, natural abundance, low cost, and non‐toxicity. However, most of these Fe‐based SC electrodes suffer from poor conductivity and/or electrochemical instability, which seriously impede their implementation as high‐performance electrodes for SCs. To settle these issues, substantial efforts have been made in improving their conductivity and cycling stability, and great processes have been achieved. Here, recent research advances in the rational design and synthesis of diverse Fe‐based nanostructured electrodes and their capacitive performance for SCs are presented. Besides, challenges and prospects of Fe‐based materials as advanced negative electrodes for SCs are also discussed.  相似文献   

5.
The "apparent" cation transference number within cellophane is determined for HCl, KCl, NH4Cl, NaCl, and LiCl. The method consists in measuring the E.M.F. in a concentration chain employing Ag:AgCl electrodes or calomel electrodes and calculating from formulas derived for cases of simple, unconstrained diffusion. The transference numbers and the cation mobilities relative to the chloride ion were found to be higher in the cellophane (relative cation mobilities increased about 40 per cent). The effect of the membrane is discussed. It is emphasized that with the introduction of a membrane as a liquid junction new factors are introduced, which are not considered in the formulas ordinarily used. Such factors may be activity changes due to dimensional or other reasons and particularly electrical effects exhibited by the membrane upon the ionic diffusion. Accordingly the transference number, as determined, may lack well defined physical significance.  相似文献   

6.
The effect of both a positive and a negative applied potential on the p-NPA hydrolysis activity of bovine carbonic anhydrase (BCA) immobilized on graphite rods has been investigated. Background experiments show that the pH-activity profile for BCA free in solution is not affected by either a negative or a positive potential applied to graphite rods placed in the same solution. However, the activity of BCA immobilized by covalent attachment to a graphite rod is influenced by a potential externally applied to the graphite rod. An overall increase in activity (as determined by the initial rate of the p-NPA hydrolysis reaction) is observed in the presence of a -0.2 V (Ag/AgCl) applied potential, while decreased activity is evident at +0.6 V (Ag/AgCl). This is indicative of an electrolyte anion effect rather than a local pH effect. In the presence of the specific anion inhibitors Cl(-) and SCN(-), the relative BCA activity increases at -0.2 V (Ag/AgCl) and decreases at +0.6 V (Ag/AgCl) are consistent with the different BCA inhibition constants for Cl(-) and SCN(-). Accelerated loss of immobilized BCA activity also accompanies the application of the external potentials, particularly at +0.6 V (Ag/AgCl). Results described here represent an early example of potentiostatic control of nonredox enzyme activity. Several possible mechanisms are discussed including specific anion inhibition, enzyme surface charge/charged support material interactions, and charged product inhibition. It is likely that a combination of such mechanisms is operational in this system. The implications of external potentials affecting the activity of immobilized enzymes in the design of stable immobilized enzyme electrodes are also discussed.  相似文献   

7.
The performance of lithium and sodium‐ion batteries is partly determined by the microstructures of the active materials and anodes. Much attention has been paid to the construction of various nanostructured active materials, with emphasis on optimizing the electronic and ionic transport kinetics, and structural stability. However, less attention has been given to the functionalization of electrode microstructure to enhance performance. Therefore, it is significant to study the effect of optimized microstructures of both active materials and electrodes on the performance of batteries. In this work, porous MoS2/carbon spheres anchored on 3D interconnected multiwall carbon nanotube networks (MoS2/C‐MWCNT) are built as sodium‐ion battery anodes to synergistically facilitate the sodium‐ion storage process. The optimized MoS2/C‐MWCNT possesses favorable features, namely few‐layered, defect‐rich, and interlayer‐expanded MoS2 with abundant mesopores/macropores and carbon incorporation. Notably, the presence of 3D MWCNT network plays a critical role to further improve interparticle and intraparticle conductivity, sodium‐ion diffusion, and structural stability on the electrode level. As a result, the electrochemical performance of optimized MoS2/C‐MWCNT is significantly improved. This study suggests that rational design of microstructures on both active material and electrode levels simultaneously might be a useful strategy for designing high performance sodium‐ion batteries.  相似文献   

8.
Integrated design of both porous structure and crystalline morphology is expected to open up the way to a new class of materials. This report demonstrates new nanostructured Li4Ti5O12 materials with hierarchically porous structures and flower‐like morphologies. Electrochemical studies of the electrodes of Li‐ion and Na‐ion batteries clearly reveal the advantage of nanoarchitectural design of active materials. In addition, the temperature dependence of Na+‐insertion/extraction capacity in relation to Li4Ti5O12 electrodes is for the first time evaluated and it is found that elevation of the cell operating temperature effectively improves the rate capability of the Na‐ion batteries. Based on the new findings, it is suggested that specially designed Li4Ti5O12 materials allow for high‐performance Na‐ion batteries that are available as large‐scale storage devices for applications such as automotive and stationary energy storage.  相似文献   

9.
New types of organic-inorganic hybrid nanocomposites based on nanosized titanium oxide(IV) (TiO2, particle size <100 nm) and carbon nanotubes (CNT, outer diameter of 10–15 nm, inner diameter of 2–6 nm, and length of 0.1–10 μm) and phosphatidylcholine were elaborated for improvement of analytical characteristics of screen printed electrodes. These nanomaterials were employed as an interface for immobilization of skeletal myoglobin. Electroanalytical and electrokinetic behavior of myoglobin on such interfaces was characterized with cyclic voltammetry (CV) and square wave voltammetry (SWV). Direct unmediated electron transfer between heme of immobilized myoglobin and electrodes modified with titanium oxide or carbon nanotubes was registered. The midpoint (redox) potential of the myoglobin Fe3+/Fe2+ E 1/2 = ?0.263 V for electrodes modified with CNT and E 1/2 = ?0.468 V for electrodes modified with TiO2 was observed (vs. Ag/AgCl reference electrode).  相似文献   

10.
Graphene and quasi‐2D graphene‐like materials with an ultrathin thickness have been investigated as a new class of nanoscale materials due to their distinctive properties. A novel “molecular tools‐assistances” strategy is developed to fabricate two kinds of graphene‐based electrodes, ultrathin Fe‐doped MnO2 network coverage–graphene composites (G‐MFO) and ultrathin MoS2 network coverage–graphene composites (G‐MoS2) with special hierarchical structures. Such structures enable a large contact interface between the active materials and graphene and thus fully exploit the synergistic effect from both the high specific capacitance of MFO or MoS2 and the superb conductivity of graphene. Benefiting from their unique structural features, G‐MFO and G‐MoS2 films directly use as free‐standing electrodes for flexible asymmetric supercapacitors with a nonaqueous gel electrolyte. The device achieves a high energy/power density, superior flexibility, good rate capability as well as outstanding performance stability even at a high temperature. This work represents a promising prototype to design new generation of hybrid supercapacitors for future energy storage devices.  相似文献   

11.
An ab initio approach was utilized to explore the electronic transport properties of 4′-thiolate-biphenyl-4-dithiocarboxylate (TBDT) sandwiched between two electrodes made of various materials X (X?=?Cu, Ag, and Au). Analysis of current–voltage (I–V) characteristics, rectification performance, transmission functions, and the projected density of states (PDOS) under various external voltage biases showed that the transport properties of these constructed systems are markedly impacted by the choice of electrode materials. Further, Cu electrodes yield the best rectifying behavior, followed by Ag and then Au electrodes. Interestingly, the rectification effects can be tuned by changing the torsion angle between the two phenyl rings, as well as by stretching the contact distances between the end group and the electrodes. For Cu, the maximum rectifying ratio increases by 37 % as the contact distance changes from 1.7 Å to 1.9 Å. This is due to an increase in coupling strength asymmetry between the molecule and the electrodes. Our findings are compared with the results reported for other systems. The present calculations are helpful not only for predicting the optimal electrode material for practical applications but also for achieving better control over rectifying performance in molecular devices.  相似文献   

12.
In this study, the synthesis of SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %) has been investigated under acidic conditions by using P123 as a template via the direct method. The nanocomposites of SBA-15 were synthesized by the same method and by the addition of silver salt. Finally, the nanocomposite materials were examined for the removal of mercury ions from wastewater as an adsorbent by the reverse titration method. Characterization was carried out through x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption-desorption (Brunauer–Emmett–Teller). XRD spectra confirmed the presence of silver nanoparticles within the amorphous silica matrix of SBA-15. The Barrett–Joyner–Halenda analysis showed that SBA-15 and SBA-15/Ag have a narrow pore size distribution. SEM images demonstrated that the morphology of the matrix of SBA-15 is in spherical state. Furthermore, wavelength dispersive x-ray spectroscopy identified the presence and distribution of silver nanoparticles inside the pore channels and outside of them. Typical TEM images of SBA-15 and SBA-15/Ag (5 wt.%) indicated a regular hexagonal pore structure with long-range order and long channels. In SBA-15/Ag (5 wt.%) sample, the nanoparticles of silver was found into the pores and outside of them. The removal of mercury ions from wastewater using mesoporous silica nanocomposite containing silver nanoparticles was studied by the reverse titration analysis. The best capacity of adsorption of mercury ions from wastewater was obtained for SBA-15/Ag (5 wt.%) sample, which was equal to 42.26 mg/g in 20 min at pH of 7. The Freundlich model was used to explain the adsorption characteristics for the heterogeneous surface, and \( {K}_{\mathrm{f}} \) (adsorption capacity) and n (adsorption intensity) were determined for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %). The value of R 2 was about 0.99, 0.99, 0.98, and 0.98 and K f was about 42, 48, 58, and 58 mg/g for SBA-15/Ag, SBA-15/Ag (2.5 %), SBA-15/Ag (5 %), and SBA-15/Ag (10 %), respectively. Furthermore, the values of n >1 show a favorable adsorption process for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials. Moreover, the Langmuir isotherm model evaluation showed that the correlation coefficients for all concentrations were R 2 >0.99, indicating that Hg (II) ions were adsorbed on the surface of SBA-15/Ag via chemical and physical interaction. Additionally, the analytic hierarchy process (AHP) and Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) methods that depend on the criteria of the surface area, amount of adsorbent, pore volume, and cost of synthesis were used. The evaluation of results showed that the best sample was SBA-15/Ag (5 wt.%). Furthermore, the research work highlighted the antibacterial nanocomposite with suitable adsorption of Hg (II) ions from water solutions and supported its potential for environmental applications. This nanocomposite can be used in the absorption domain of Hg (II) ions from water solutions.  相似文献   

13.
High energy‐density, low‐cost batteries are critically important to a variety of applications ranging from portable electronics to electric vehicles (EVs) and grid‐scale storage. While tremendous research effort has been focused on new materials or chemistries with high energy‐density potential, design innovations such as low‐tortuosity thick electrodes are another promising path toward higher energy density and lower cost. Growing demand for fast‐charging batteries has also highlighted the need for negative electrodes that can accept high rate charging without metal deposition; low tortuosity can be a benefit in this regard. However, a general and scalable fabrication method for low‐tortuosity electrodes is currently lacking. Here an emulsion‐based, magnetic‐alignment approach to producing thick electrodes (>400 µm thickness) with ultrahigh areal capacity (up to ≈14 mAh cm?2 vs 2–4 mAh cm?2 for conventional lithium ion) is reported. The process is demonstrated for LiCoO2 and meso‐carbon microbead graphite. The LiCoO2 cathodes are confirmed to have low tortuosity via DC‐depolarization experiments and deliver high areal capacity (>10 mAh cm?2) in galvanostatic discharge tests at practical C‐rates and model EV drive‐cycle tests. This simple fabrication method can potentially be applied to many other active materials to enable thick, low‐tortuosity electrodes.  相似文献   

14.
Hydrogenase (H2 ase) purified from phototropic bacteriumThiocapsa roseopersicina was coassembled with carbon nanotubes (CNTs) on glass carbon electrodes. Both oxidized CNTs and Nafion-CNT composites were used to modify the electrodes. The pure H2 are formed dot-like domains, while the oxidized CNT-H2 ase and Nafion-CNT-H2 ase composites formed wire-like and large closely packed aggregates, respectively. The reductive potentials for the [4Fe-4S]2+/1+ clusters of H2ase were at about −500, −650, and −700 mV (vs Ag/AgCl) for the electrodes modified with pure H2ase, Nafion-SWNT-H2ase, and Nafion-MWNT-H2ase composites, respectively. Potential step chronocoulometry measurements indicated a larger charge-transfer diffusion coefficient between the H2ase and electrodes when the CNTs were co-assembled with H2ase, suggesting that the CNTs can not only act as a supporting layer to immobilize enzymes, but also act as a highly conductive wire throughout the films.  相似文献   

15.
Emergence of new pathogenic viruses along with adaptive potential of RNA viruses has become a major public health concern. Therefore, it is increasingly crucial to investigate and assess the antiviral potential of nanocomposites, which is constantly advancing area of medical biology. In this study, two types of nanocomposites: Ag/NiO and Ag2O/NiO/ZnO with varying molar ratios of silver and silver oxide, respectively have been synthesised and characterised. Three metal/metal oxide (Ag/NiO) composites having different amounts of Ag nanoparticles (NPs) anchored on NiO octahedrons are AN-5 % (5 % Ag), AN-10 % (10 % Ag) and AN-15 % (15 % Ag)) and three ternary metal oxide nanocomposites (Ag2O/NiO/ZnO) i.e., A/N/Z-1, A/N/Z-2, and A/N/Z-3 with different molar ratios of silver oxide (10 %, 20 % and 30 %, respectively) were evaluated for their antiviral potential. Cellular uptake of nanocomposites was confirmed by ICP-MS. Intriguingly, molecular docking of metal oxides in the active site of nsP3 validated the binding of nanocomposites to chikungunya virus replication protein nsP3. In vitro antiviral potential of nanocomposites was tested by performing plaque reduction assay, cytopathic effect (CPE) analysis and qRT-PCR. The nanocomposites showed significant reduction in virus titre. Half-maximal inhibitory concentration (IC50) for A/N/Z-3 and AN-5 % were determined to be 2.828 and 3.277 µg/mL, respectively. CPE observation and qRT-PCR results were consistent with the data obtained from plaque reduction assay for A/N/Z-3 and AN-5 %. These results have opened new avenues for development of nanocomposites based antiviral therapies.  相似文献   

16.
The usefulness of reductive electrochemical detection at mercury drop electrodes has been determined for platinum complexes separated by solvent-generated anion-exchange high-performance liquid chromatography. Both current-sampled dropping mercury and hanging mercury drop electrodes (DME and HMDE) provide significant advantages over UV absorbance and off-line non-flame atomic absorption detection. The effects of chromatographic and polarographic parameters on analytical system performance have been investigated. By raising the detector cell temperature, the detector response to cis-dichlorodiammineplatinum(II) (DDP) can be shifted anodically to 0.0 V vs. Ag/AgCl, thereby increasing detector selectivity for this compound. The noise-limited minimum detectable quantities of DDP with DME and HMDE are 1.8 ng and 70 pg injected, respectively. DDP can be determined in untreated urine at levels below 100 ng/ml.  相似文献   

17.
Sodium‐ion batteries are promising for grid‐scale storage applications due to the natural abundance and low cost of sodium. However, few electrodes that can meet the requirements for practical applications are available today due to the limited routes to exploring new materials. Here, a new strategy is proposed through partially/fully substituting the redox couple of existing negative electrodes in their reduced forms to design the corresponding new positive electrode materials. The power of this strategy is demonstrated through the successful design of new tunnel‐type positive electrode materials of Na0.61[Mn0.61‐xFexTi0.39]O2, composed of non‐toxic and abundant elements: Na, Mn, Fe, Ti. In particular, the designed air‐stable Na0.61[Mn0.27Fe0.34Ti0.39]O2 shows a usable capacity of ≈90 mAh g?1, registering the highest value among the tunnel‐type oxides, and a high storage voltage of 3.56 V, corresponding to the Fe3+/Fe4+ redox couple realized for the first time in non‐layered oxides, which was confirmed by X‐ray absorption spectroscopy and Mössbauer spectroscopy. This new strategy would open an exciting route to explore electrode materials for rechargeable batteries.  相似文献   

18.
This study aimed to synthesize and characterize materials containing silver nanoparticles (AgNP) with polyphosphates (sodium trimetaphosphate (TMP) or sodium hexametaphosphate (HMP), and evaluate their effect against Candida albicans and Streptococcus mutans. The minimum inhibitory concentration (MIC) was determined, which was followed by the quantification of the biofilm by counting colony-forming units (CFUs), the amount of metabolic activity, and the total biomass. The MICs revealed greater effectiveness of composites containing 10% Ag (TMP + Ag10% (T10) and HMP + Ag10% (H10)) against both microorganisms. It was observed that T10 and H10 reduced the formation of biofilms by 56–76% for C. albicans and by 52–94% for S. mutans for total biomass and metabolic activity. These composites promoted significant log reductions in the number of CFUs, between 0.45–1.43 log10 for C. albicans and 2.88–3.71 log10 for S. mutans (p < .001). These composites demonstrated significant antimicrobial activity, especially against S. mutans, and may be considered a potential alternative for new dental materials.  相似文献   

19.

In this paper, we have inspected the optical characteristics of one-dimensional periodic structure (1DPS) of TiO2 and MgF2 dielectric materials with defect layer of liquid crystal (LC) sandwiched with two silver layers, i.e., (TiO2|MgF2)3|Ag|LC|Ag|(TiO2/MgF2)3 using transfer matrix method (TMM). The optical tunable properties of considered periodic structures investigated at different incident angles and temperatures for TE and TM modes. Our study shows that absorption peak of 1DPS varies with incident angle and temperature. The defect layer (Ag-LC-Ag), sandwiched LC within two metallic (Ag) layers, exhibits the surface plasmon waves at the metal LC interfaces. The effect of surface plasmon waves can be better understand through the optical sensing property of such defect periodic structure. The detailed study concludes that such a type of one-dimensional periodic structure (1DPS) may be useful to design a tunable sensor and monochromatic filter.

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20.
A seawater splitting photoelectrochemical cell featuring a nanostructured tungsten trioxide photoanode that exhibits very high and stable photocurrents producing chlorine with average 70% Faradaic efficiency is described. Fabrication of the WO3 electrodes on fluorine‐doped tin oxide substrates involves a simple solution‐based method and sequential layer‐by‐layer deposition with a progressively adjusted amount of structure‐directing agent in the precursor and a two‐step annealing. Such a procedure allows tailoring of thick, highly porous, structurally stable WO3 films with a large internal photoactive surface area optimizing utilization of visible light wavelengths by the photoanode. With the application of an anodic potential of 0.76 V versus Ag/AgCl reference electrode (0.4 V below the thermodynamic Cl2/Cl? potential) in synthetic seawater, the designed WO3 photoanodes irradiated with simulated 1 sun AM 1.5G light reach currents exceeding 4.5 mA cm?2. Photocurrents close to 5 mA cm?2 are attained in the case of fresh water splitting using 1 m methane–sulfonic acid supporting electrolyte with oxygen evolved at the WO3 photoanode. The amount of formed hydrogen is determined by discharging the palladium sheet electrode employed as a cathode. Collection of hydrogen in the form of a hydride opens, more generally, the prospect of subsequently using such materials as anodes in batteries employing oxygen reduction cathodes.  相似文献   

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