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The effect of various alkaline metal ions on electrochemical behavior of lead electrode in sulfuric acid solution has been investigated. It was found that “the specific anodic oxidation peak” appears at the cathodic scan in cyclic voltammogram of lead electrode in sulfuric acid solution containing Li 2 SO 4 , K 2 SO 4 , Na 2 SO 4 , Rb 2 SO 4 , or Cs 2 SO 4 . The height of the specific anodic oxidation peak varies with the alkaline sulfate in the solution; K 2 SO 4 >> Na 2 SO 4 > Cs 2 SO 4 > Rb 2 SO 4 > Li 2 SO 4 . It should be note that alkaline ions exist in lead sulfate formed on lead electrode in sulfuric acid solution containing potassium sulfate when the electrode was immersed in the solution at the rest potential for more than 1 h. [ABSTRACT FROM AUTHOR]

Abstract: The effect of lignosulfonate (LS) on electrochemical reaction of lead electrode (as a model of negative electrode) has been investigated in 1M, 3M, or 7.1M H2SO4 aqueous solution with 0, 10, 100 or 1000mgl−1 of LS using cyclic voltammetry (CV) combined with in situ electrochemical atomic force microscopy (EC-AFM), as well as rotating ring disk electrode (RRDE). The anodic peaks of the CVs, which correspond to overall reaction of , shifted positive when LS was added or the concentration of H2SO4 was lower. The anodic capacities of the CVs increased with addition of LS when the concentration of H2SO4 was lower. When LS was added, the anodic capacities of the CVs usually increased especially in less concentrated H2SO4 solution at higher sweep rate, while the anodic capacity slightly decreased in 7.1M H2SO4 solution with addition of LS at sweep rate of 10mVmin−1; that is, in most concentrated H2SO4 solution at lower sweep rate in this paper. Two cathodic peaks of the CVs were observed when LS was added, and the peak at lower potential shifted more negative with increase of LS. Lead sulfate crystals dissolved at more negative potential with increase of LS. LS up-took Pb2+ ions in H2SO4 aqueous solution during discharging. [Copyright &y& Elsevier]

Abstract: The influence of quinone structures related to the formation of the “colloidal deposit” on Pb electrode immersed into water containing lignin preparations or pure organic compounds has been investigated. It was found that quinone structures in lignin preparations, as well as in pure organic compounds, play an important role in the formation of the “colloidal deposit”. [Copyright &y& Elsevier]

Palladium nanoparticles encapsulated into graphite (Pd–graphite intercalation compound: Pd–GIC) were produced from two kinds of graphite, natural graphite (average flake size: 270 μm) and kish graphite (average flake size: 15 μm). Hydrogen storage properties of Pd–GIC have been investigated by means of differential scanning calorimetry (DSC) between 473 and 573 K at 1.0 MPa hydrogen pressure. It is found from the DSC measurement that Pd–GIC can absorb and emit hydrogen. [Copyright &y& Elsevier]

The decay of nano-islands on the surface of a Au(111) electrode, in contact with 50 mM sulfuric acid aqueous solution under an applied potential in the range of 0.15–1.2 V, has been investigated using electrochemical atomic force microscopy (EC-AFM). The results are compared with those previously obtained for Au(100). With either orientation, it is found that the area of the top layer of multi-layered islands decreases linearly with time at any applied potential. It was also found that the decay rate, defined as the rate of decrease of the number of atoms in the top-layer of the islands per second, increases with the magnitude of the applied potential. Further, the decay rate of the top layer of the islands on Au(111) is almost the same as that on Au(100). [Copyright &y& Elsevier]

The reaction between lignin and the surface oxide layer on Pb plates was studied by dipping experiments in ultra pure water with lignin, anodic polarograms in sulfuric acid solution with or without lignin and also scanning electron microscopy (SEM) observations of the sample surface after anodic polarization. It is found that the lignin reacts with the surface oxide on the Pb plates in ultra pure water with lignin to reaction products containing Pb and the lignin and they grew preferentially at the interface between Pb and the surface oxide. The deposits formed on the surface suppress to passivate the Pb surface under sulfuric acid solution. [Copyright &y& Elsevier]

Pb(1 0 0) and Pb(1 1 1) single crystals in 50 mM H2SO4 aqueous solution have been investigated by in situ electrochemical atomic force microscopy (EC-AFM) under potential control. We have succeeded in observating high resolution images of Pb(1 0 0) and Pb(1 1 1) single crystals, as well as high resolution and morphological images of PbSO4 crystals formed on the Pb single crystals. We found that the top face of PbSO4 crystals formed on Pb(1 0 0) is PbSO4(0 0 1), while that on Pb(1 1 1) is PbSO4(1 0 0). We also found that the atomic rows along the [1 0 0] and [0 1 0] direction of PbSO4(0 0 1) surface were parallel with those along the [0 1 1] and [0 1 1¯] direction of the Pb(1 0 0) substrate, while those along the [0 1 0] and [0 0 1] direction of the PbSO4 (1 0 0) surface were parallel with those along the [0 1 1¯] and [1¯ 1 1] direction of the Pb(1 1 1) substrate. [Copyright &y& Elsevier]

Biofilms, mainly comprised of bacteria, form on materials' surfaces due to bacterial activity. They are generally composed of water, extracellular polymeric substances (polysaccharides, proteins, nucleic acids, and lipids), and bacteria. Some bacteria that form biofilms cause periodontal disease, corrosion of the metal materials that make up drains, and slippage. Inside of a biofilm is an environment conducive to the growth and propagation of bacteria. Problems with biofilms include the inability of disinfectants and antibiotics to act on them. Therefore, we have investigated the potential application of alternating electromagnetic fields for biofilm control. We obtained exciting results using various materials' specimens and frequency conditions. Through these studies, we gradually understood that the combination of the type of bacteria, the kind of material, and the application of an electromagnetic field with various low frequencies (4 kHz–12 kHz) changes the circumstances of the onset of the biofilm suppression effect. In this study, relatively high frequencies (20 and 30 kHz) were applied to biofilms caused by Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis), and quantitative evaluation was performed using staining methods. The sample surfaces were analyzed by Raman spectroscopy using a Laser Raman spectrometer to confirm the presence of biofilms on the surface. [ABSTRACT FROM AUTHOR]

Thus far, biofouling on material surfaces has been investigated from various viewpoints, and concrete methods for its evaluation have been proposed. Biofilms, which are formed by bacterial activities, are essential components of biofouling. They play an important role in the occurrence of biofouling on the materials of structures, which leads to serious economic loss. Therefore, the establishment of countermeasures for biofilm formation and its control are needed urgently. In addition, appropriate evaluation techniques to measure biofilm formation are required. Thus far, we have used scientific evaluation devices and techniques such as an optical microscope and Raman spectroscopy to evaluate biofouling/biofilms. In this study, we used the silane coating of dispersed silver and copper nanopowder rather than that of dispersed organometals. Specimens were immersed into a laboratory biofilm reactor. Then, the biofouling behavior on the sheets was investigated using an optical microscope, Raman spectroscopy, a focused ion beam system (FIB), and scanning electron microscopy (SEM). The optical-microscope observations showed many deposits on the specimens without any metallic dispersions. Although the amount of deposits on the specimens decreased with copper dispersions, many deposits were still observed on them with silver dispersion. These deposits were not confirmed by Raman spectroscopy because of the surface plasmon resonance of silver. Next, we observed and analyzed the specimens using the FIB system (combination of FIB–SEM and EDX) instead of Raman spectroscopy. The SEM image showed that the deposition had formed pores and irregularities on the specimens. FIB–SEM confirmed the existence of deposition on coating layers and revealed that it originated from biooraganisms. Based on these experiments, we could conclude that the structure of antifouling coating could be observed and analyzed using a combination of FIB–SEM and EDX even when other analysis methods are not useful because of various reasons. [ABSTRACT FROM AUTHOR]

The precise observation of a solid–liquid interface by means of frequency modulation atomic force microscopy (FM-AFM) was performed, demonstrating its applicability to a study on lead acid batteries using an electrochemical test cell for in-liquid FM-AFM embedded with a specialized cantilever holder. The consistency and reproducibility of each surface profile observed via amplitude modulation AFM and FM-AFM were verified properly in a strong acidic electrolyte. In terms of FM-AFM, the ability to observe remarkable changes in the force mapping is the most beneficial, especially near the negative electrode surface. The localization of lignosulfonate (LS) added into the electrolyte as an expander could be visualized since this characteristic force mapping was captured when LS was added to electrolyte. [ABSTRACT FROM AUTHOR]

Biofilms have caused many problems, not only in the industrial fields, but also in our daily lives. Therefore, it is important for us to control them by evaluating them properly. There are many instrumental analytical methods available for evaluating formed biofilm qualitatively. These methods include the use of Raman spectroscopy and various microscopes (optical microscopes, confocal laser microscopes, scanning electron microscopes, transmission electron microscopes, atomic force microscopes, etc.). On the other hand, there are some biological methods, such as staining, gene analyses, etc. From the practical viewpoint, staining methods seem to be the best due to various reasons. Therefore, we focused on the staining method that used a crystal violet solution. In the previous study, we devised an evaluation process for biofilms using a color meter to analyze the various staining situations. However, this method was complicated and expensive for practical engineers. For this experiment, we investigated the process of using regular photos that were quantified without any instruments except for digitized cameras. Digitized cameras were used to compare the results. As a result, we confirmed that the absolute values were different for both cases, respectively. However, the tendency of changes was the same. Therefore, we plan to utilize the changes before and after biofilm formation as indicators for the future. [ABSTRACT FROM AUTHOR]

Biofilms are a result of bacterial activities and are found everywhere. They often form on metal surfaces and on the surfaces of polymeric compounds. Biofilms are sticky and mostly consist of water. They have a strong resistance to antimicrobial agents and can cause serious problems for modern medicine and industry. Biofilms are composed of extracellular polymeric substances (EPS) such as polysaccharides produced from bacterial cells and are dominated by water at the initial stage. In a series of experiments, using Escherichia coli, we developed three types of laboratory biofilm reactors (LBR) to simulate biofilm formation. For the first trial, we used a rotary type of biofilm reactor for stirring. For the next trial, we tried another rotary type of reactor where the circular plate holding specimens was rotated. Finally, a circular laboratory biofilm reactor was used. Biofilms were evaluated by using a crystal violet staining method and by using Raman spectroscopy. Additionally, they were compared to each other from the practical (industrial) viewpoints. The third type was the best to form biofilms in a short period. However, the first and second were better from the viewpoint of "ease of use". All of these have their own advantages and disadvantages, respectively. Therefore, they should be properly selected and used for specific and appropriate purposes in the future. [ABSTRACT FROM AUTHOR]

Biofilms are the result of bacterial activity. When the number of bacteria (attached to materials' surfaces) reaches a certain threshold value, then the bacteria simultaneously excrete organic polymers (EPS: extracellular polymeric substances). These sticky polymers encase and protect the bacteria. They are called biofilms and contain about 80% water. Other components of biofilm include polymeric carbon compounds such as polysaccharides and bacteria. It is well-known that biofilms cause various medical and hygiene problems. Therefore, it is important to have a sensor that can detect biofilms to solve such problems. Graphene is a single-atom-thick sheet in which carbon atoms are connected in a hexagonal shape like a honeycomb. Carbon compounds generally bond easily to graphene. Therefore, it is highly possible that graphene could serve as a sensor to monitor biofilm formation and growth. In our previous study, monolayer graphene was prepared on a glass substrate by the chemical vapor deposition (CVD) method. Its biofilm forming ability was compared with that of graphite. As a result, the CVD graphene film had the higher sensitivity for biofilm formation. However, the monolayer graphene has a mechanical disadvantage when used as a biofilm sensor. Therefore, for this new research project, we prepared bilayer graphene with high mechanical strength by using the CVD process on copper substrates. For these specimens, we measured the capacitance component of the specimens' impedance. In addition, we have included a discussion about the possibility of applying them as future sensors for monitoring biofilm formation and growth. [ABSTRACT FROM AUTHOR]

Steelmaking slags are a promising resource as artificial seaweed beds for the reconstitution of marine environments. To grow seaweed well, the formation of biofilms is an essential process in biofouling. This study focused on the formation of initial biofilms on steelmaking slag samples and analyzed the resulting bacterial communities using the next-generation sequencing technique. Three types of steelmaking slag were submerged in an area of Ise Bay in Mie Prefecture, Japan, for 3 and 7 days in the summer and winter seasons to allow the formation of biofilms. The bacterial communities of these biofilms were richer in sulfur-oxidizing bacteria compared to the biofilms formed on polyurethane sponges. It was found that Helicobacteraceae dominantly grew on the biofilms formed on the slag samples. This shows that steelmaking slags have potential to be used as artificial seaweed beds and marine water purifiers. [ABSTRACT FROM AUTHOR]

Abstract: Negative plate lugs of flooded lead-acid battery were corroded during partial state-of-charge (PSoC) pattern cycle life tests simulated from stop and go vehicle driving. Potential step was applied to Pb–Ca–Sn alloy electrode at various potential and time regimes, and the electrode surface was observed by in situ electrochemical atomic force microscope (EC-AFM) to investigate the corrosion mechanisms during the potential step cycles. It was found out that the severe corrosion occurs when the oxidation of Pb to PbSO4 and partial reduction of passive layer of PbSO4 take turns many times. It was also found out that the periodic full charge, the optimization of the alloy composition, addition of the material that may make the reaction mechanism change to electrolyte were effective to suppress the corrosion rate. [Copyright &y& Elsevier]

Abstract: Potential step was applied to Pb–Ca–Sn alloy electrode at various potential and time regimes. No severe corrosion was observed during potential step cycle with cathodic potential under −140mV or over −40mV versus Pb/PbSO4 (3.39M H2SO4), or at constant potential without stepping. On the other hand, the Pb–Ca–Sn alloy was severely corroded during potential step with cathodic potential from −120mV to −60mV and with anodic potential of +40mV or more positive. The corrosion could not be decreased with periodical rest at 0mV, while it could be decreased with periodical reduction at high polarization of, e.g. −160mV. It was found out that the severe corrosion occurs when the oxidation of Pb to PbSO4 and partial reduction of passive film of PbSO4 take turns many times. [Copyright &y& Elsevier]

Abstract: Electrochemical properties of lead dioxides, formed on various lead alloy substrates (Pb–In, Pb–Sn, Pb–Sb, Pb–Tl and Pb–Bi), were investigated using electrochemical techniques with X-ray diffraction (XRD) and electron probe micro analyzer (EPMA). Additive elements, selected by applying Hume-Rothery rules, have similar atomic radius and electronegativity to lead. The reduction capacity of lead dioxides that were formed on Pb–Sb and Pb–Sn alloy substrates decreased, whereas the reduction capacity of lead dioxides formed on Pb–In, Pb–Tl and Pb–Bi alloy substrate increased, compared with those formed on the pure lead substrate. The change of the lattice constant of β-lead dioxides and the existence of additive elements in the lead dioxide layer were confirmed from the analysis results of XRD and EPMA. We concluded that the substitution of additive elements for lead in the β-lead dioxide caused the change of its lattice constant to affect the reduction capacity. [Copyright &y& Elsevier]

The surface morphologies of lead dioxide layers, which were formed on a pure lead substrate and the Pb–Sb a (100 ppm–3%) alloy substrate, were directly observed with the electrochemical atomic force microscope (EC-AFM) in 1.250 g/cm3 sulfuric acid electrolyte and then they were analyzed with X-ray diffraction (XRD). The particle size of the lead dioxide became significantly smaller with the increase of the amount of antimony in the substrate alloy. From this result, it was considered that such small particle size serves to increase the reaction area of the positive electrode and the total electrical contact area between the positive active material (PAM) particles. Also, the interface resistance between grid and the PAM can become lower, if the density of the corrosion layer formed around the grid were to be higher for the small particles. By XRD analysis, it was found that the inter-atomic distance of the lead dioxide on the Pb–3 wt.% Sb alloy substrate shrank compared to that on a pure Pb substrate. [Copyright &y& Elsevier]