Galvanic Cell

We report a facile and efficient method, nanochannel-confined galvanic displacement, to fabricate uniform and controllable CuInSe 2 nanotube arrays using the porous Au-coated anodic aluminium oxide template with a narrow ring-shaped Al foil surrounding on its outside edge. This method provides a new approach for fabricating nanotube arrays.

Activity of tin in liquid Sn-Bi-Sb was derived by EMF measurement of galvanic cell with fused salts electrolyte in the temperature range of 700 to 1000K in the whole composition range. Activity of tin at 900K shows very small positive deviation from Raoult's law for Sn-Bi alloys and moderately negative deviation for Sn-Sb alloys. Activity of ternary alloys along SbyBi(1-y)-Sn (y=0.25, 0.50 and 0.75) shows negative deviation and the deviation becomes large with increasing Sb content. Excess free energy of mixing is derived using Darken's method for Gibbs-Duhem equation and the values are compared with those by model calculations based on the three constitutive binary data.

Activity of tin in liquid Sn-Bi-Sb was derived by EMF measurement of galvanic cell with fused salts electrolyte in the temperature range of 700 to 1000 K in the whole composition range. Activity of tin at 900 K shows very small positive deviation from Raoult's law for SnBi alloys and moderately negative deviation for Sn-Sb alloys. Activity of ternary alloys along SbyBi(1 －y)-Sn (y ＝0.25, 0.50 and 0.75) shows negative deviation and the deviation becomes large with increasing Sb content. Excess free energy of mixing is derived using Darken's method for Gibbs-Duhem equation and the values are compared with those by model calculations based on the three constitutive binary data. 論　文

Electrodeposited zinc-nickel coatings are broadly used as sacrificial coatings for steel since many years in the automotive industry and for other high corrosion resistant applications. The best corrosion resistance is obtained with ZnNi deposits having 12 – 15 % Ni in the alloy. Many studies were performed showing the influence of nickel content in the alloy. In industrial plating electrolytes other metals than Zn and Ni can be present. In alkaline zinc-nickel electrolytes mild steel is usually used as anode material. Depending on electrolyte composition and plating conditions more or less iron can be dissolved by anodic dissolution into the electrolyte. It is well known that the iron is codeposited into the zinc nickel alloy, but the effect on the alloy properties was never systematic investigated. In this study the influence of up to 800 mg/L iron in commercially used alkaline zinc nickel processes is investigated. Up to 8% iron is amorphously codeposited in the alloy. No new iro...

NiPt alloys were prepared successfully by galvanic replacement reaction on the surface of Ni films. The electrolytic deposition of Ni films was investigated to get the high qualities of Ni films for the galvanic reaction. The influence of the electrolytic currents on the morphology and thickness of Ni films were observed by SEM. The thickness and roughness of the Ni films increase with the increase of electrolytic currents. XRD patterns showed that Ni films were formed in the crystal phase of Ni corresponding to face centered cubic structure. Pure Ni films obtained by annealing the films in hydrogen medium were used to prepare NiPt alloys due to galvanic reaction of Pt2+ with Ni2+ in H2PtCl6 solution. The influence of the H2PtCl6 solution concentration on the composition of NiPt alloys were investigated by EDX. The analyses results showed that NiPt alloy formed by using high solution concentration of H2PtCl6 has high composition of Pt. The electrocatalytic activities of both Ni film...

The activities of Au-modified Cu electrodes toward glucose oxidation are evaluated according to their fabrication conditions and physico-chemical properties. The Au-modified Cu electrodes are fabricated by the galvanic displacement of Au on a Cu substrate and the characteristics of the Au particles are controlled by adjusting the displacement time. From the glucose oxidation tests, it is found that the Au modified Cu has superior activity to the pure Au or Cu film, which is evidenced by the negative shift in the oxidation potential and enhanced current density during the electrochemical oxidation. Though the activity of the Au nanoparticles is a contributing factor, the enhanced activity of the Au-modified Cu electrode is due to the increased oxidation number of Cu through the electron transfer from Cu to more electronegative Au. The depletion of electron in Cu facilitates the oxidation of glucose. The stability of the Au-modified Cu electrode was also studied by chronoamperometry.

Electrochemical and gravimetric measurements were used to examine the effects of neodymium and gadolinium additions on the galvanic corrosion behaviour of AM50 and AZ91D magnesium alloys coupled to A 570 Gr 36 carbon steel and AA2011-AA6082 aluminium alloys. Rare earth modified alloys showed Al 2 Nd/Al 2 Gd and Al-Mn-Nd/Al-Mn-Gd intermetallics, reduced area fraction of β-Mg 17 Al 12 phase and increased corrosion resistance due to increased surface passivity and suppression of micro-galvanic couples. Neodymium and gadolinium additions improved the galvanic corrosion resistance of AM50 alloy, but were less effective in case of the AZ91D alloy. The AA6082 alloy was the most compatible material and the AA2011 alloy was the least compatible.

In many cases, the repair strategy by using sacrificial anodes for cathodic protection in real RC structures requires additional zinc anodes after several years due to the decreasing protective area. This experimental study evaluates the effectiveness of time lag application of sacrificial anode cathodic protection applied to RC beam specimens that deteriorated severely due to chloride attack. In the experiment, sacrificial anodes and cathodic protection (SACP) were applied to 41-year-old RC beam specimens exposed to natural marine environments in which the embedded steel bars were significantly corroded. The repair work was performed in three stages. Instant-off and rest potential tests of steel bars were conducted periodically to demonstrate the time-dependent depolarization value. In the first stage, a polymer-modified mortar as a patch repair material was cast to replace the concrete in the middle tensile part with small sacrificial anodes embedded in the mortar. After the protective current reaches an equilibrium state, the sacrificial anodes are disconnected from the steel bars for a year, defined as the second stage. During the one year in the second stage, the steel bar in the patch repair area remained passive, without any sign of corrosion. As for the third stage, additional sacrificial anodes were installed in the existing concrete part to protect the steel in it. From one year of observation after applying sacrificial anodes to old concrete parts, the time lag SACP application of both in patch and non-patch repair parts was clarified to be effective in stopping the corrosion of steel bar in both parts until 20-30 years based on the service life prediction.

Duran KOCABAĞ (*) OZET Sülfür minerallerinin özyapısal özellikleri ile flotasyonları arasındaki olası ilişkiler tartışıldı. Yarı iletken özellikleri nedeni ile sülfür flotasyonunda elektrokimyasal tepkimelerin rolü değerlendirildi. Gerek cevher yatağında, gerekse cevherin zenginleştirilmesi sırasında oluşabilecek galvanik etkileşimin mekanizması açıklanarak flotasyonu nasıl etkileyebile ceği örneklerle irdelendi.

Nitrite (NO₂⁻) is a well established corrosion inhibitor for strictly closed loop cooling water systems. However, its performance is severely compromised in the presence of dissolved oxygen (DO > 1 ppm), which catalytically oxidizes nitrite to non inhibitive nitrate (NO₃⁻). This oxidation leads to depleted inhibitor levels, increased chemical consumption, reduced corrosion inhibition e iciency, and can promote nitrifying bacterial growth. This case study examines three industrial cooling units at a renowned petrochemical facility that experienced these issues, manifesting as high iron (>10 ppm) and total suspended solids (TSS > 50 ppm) leading to frequent equipment fouling. The units were transitioned from a nitrite based treatment program to a molybdate (MoO₄²⁻)based alternative. Molybdate o ers e ective corrosion protection for semi closed systems, is thermally stable, halogen resistant, and has low toxicity. Over a six-month monitoring period, the new treatment program successfully brought all critical water parameters within control limits. A key outcome was a dramatic reduction in annual chemical consumption, resulting in estimated Net cost savings over 135,000 SAR/year, while simultaneously improving system reliability and process performance indicators.

The surface limited redox replacement (SLRR) method has been used to design two-dimensional Pt-Pb nanoalloys with controlled thickness, composition, and structure. The electrochemical behavior of these alloys has been systematically studied as a function of alloy composition. A single-cell, two-step SLRR protocol based on the galvanic replacement of underpotentially deposited monolayers of Pb with Pt was used to grow epitaxial Pt 1-x Pb x (x < 0.1) alloys of up to 10 ML thickness on Au substrates. It is shown that by varying the terminating potential of the galvanic replacement step, the Pb atomic content can be controlled in the films. Electrochemical analysis of the alloys showed that the adsorption of both H and CO exhibits similar, and systematic, decreases with small increases in the Pb content. These measurements, commonly used in electrocatalysis for the determination of active surface areas of Pt, suggested area values much lower than those expected based on the net Pt composition in the alloy as measured by XPS. These results show that Pb has a strong screening effect on the adsorption of both H and CO. Moreover, changes in alloy composition result in a negative shift in the potential of the peaks of CO oxidation that scales with the increase of Pb content. The results suggest electronic and bifunctional effects of incorporated Pb on the electrochemical behavior of Pt. The study illustrates the potential of the SLRR methodology, which could be employed in the design of 2-dimensional bimetallic Pt nanoalloys for fundamental studies of electrocatalytic behavior in fuel cell reactions dependent on the nature of alloying metal and its composition.

The Surface Limited Redox Replacement (SLRR) method has been used to design two dimensional Pt-Pb nanoalloys with controlled thickness, composition and structure. The electrochemical behaviour of these alloys has been systematically studied as a function of alloy composition. A single-cell, two step SLRR protocol based on the galvanic replacement of underpotentially deposited monolayers of Pb with Pt was used to grow epitaxial Pt1-xPbx (x &lt; 0.1) alloys of up to 10 ML thickness on Au substrates. It is shown that by varying the terminating potential of the galvanic replacement step, the Pb atomic content can be controlled in the films. Electrochemical analysis of the alloys showed that the adsorption of both H and CO exhibit similar, and systematic, decreases with small increases in the Pb content. These measurements, commonly used in electrocatalysis for the determination of active surface areas of Pt, suggested area values much lower than those expected based on the net Pt compos...

Corrosion of steel in bridge structures is a growing issue worldwide. Case studies of galvanic and hybrid systems show the diverse range of challenges and corrosion hazards that are faced during the design of these systems. Data from these case studies show the effectiveness of this approach. Hybrid systems have been utilised in controlling corrosion during refurbishment work on bridges for over a decade. Galvanic systems have been around much longer. By utilising these systems individually or together there is great flexibility in design. This allows intensive concrete restoration from a hybrid system alongside the maintenance of repairs in lower risk areas from galvanic anodes. This paper presents case studies covering hybrid and galvanic systems applied to bridge structures. Included is a prestressed concrete bridge in a tidal environment, we believe to be the first of its kind fitted with a hybrid system. Tidal considerations and flooding are key challenges in corrosion mitigati...

Hybrid corrosion protection (HCP) can be used to provide corrosion arrest and prevention in degrading reinforced-concrete structures to increase their service life. The proprietary technology is a relatively new electrochemical treatment for concrete structures, having been patented in 2005 (patent GB2426008B). Due to this fact, accurate and reliable empirical data over the life span of a structure protected by an HCP system does not yet exist. This paper is the first to present over 10 years of empirical data, from one of the very first installations of HCP, providing a rigorous and reliable assessment of the structure&#39;s long-term performance. Results demonstrate that hybrid galvanic anodes exhibit a responsive behaviour to maintain the concrete environment and respond to corrosion hazards. Even after prolonged periods of low current output, the anodes respond to changing environmental conditions, providing the higher current output required to afford the necessary polarisation...

Testing methods for corrosion prevention in structures have, historically, been based on the steel polarising from the protective current. Modern galvanic systems aim to protect the steel by restoring the protective alkaline environment, rather than through polarisation. Since 2012 standard guidelines allow for alternative testing to be used [1]. Scientific testing of galvanic systems will be discussed looking at the nature of constant potential galvanic systems and comparing them to the traditional constant current impressed systems, looking in particular at unique anode behaviours such as low median current during times of low corrosion risk and responsive behaviour during corrosion hazards. This work lays out a protocol for the evaluation and testing of existing galvanic corrosion protection (CP) systems in reinforced concrete through the lens of various real-world studies. Data taken from over a decade of monitored systems are used to support the protocol. Modern testing strateg...

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Scanning Kelvin Probe (SKP) and FTIR microscopy were applied to study the atmospheric corrosion of galvanized steel coated by electrophoretic epoxy resin (ED) at a defect. The SKP was useful to determine the spatial separation of the electrochemical reactions at a defect and surrounding metal/paint interface and to evaluate the formation of the galvanic cells. FT-IR microscopy was helpful to identify the composition and distribution of the corrosion products in the galvanic cells. It was shown that the cathodic delamination of coating takes place after deposition of a thick water electrolyte film in the defect. The anodic undermining of the coating is favoured in case of atmospheric corrosion under thin electrolyte films. The anodic de-adhesion starting from defect reaching the zinc layer and from the non protected cut edge in case of exposure in the salt spray conditions was also determined. The role of the formation of confined volume underneath the delaminated paint on the rate of anodic undermining is discussed.

Press-hardened steels are commonly protected with hot-dip Al-Si coating. Due to the electrochemical complexity of this system, either before or after hot-stamping process, SKPFM was used to investigate the influence of the thermo-mechanical process on the electrochemical behaviour of the galvanic coupling. The hot-stamping process changed significantly the anodic/cathodic coupling of the coating/steel due to iron enrichment in the coating layer. Hence, a concurrent mechanism was thoroughly established, i.e., while the press hardening enhances the corrosion properties of the steel system (steel and metallic coating) through diffusion, at the same time it diminishes the cathodic protection of the Al-Si layer.

This study investigates the effects of two different catalytic activation techniques on the thermal performance of the flip-chip heat spreaders. The two activation techniques studied are thin nickel-copper strike and galvanic initiation. Thermal diffusivity and surface roughness of these heat spreaders were studied using the Nano-flash Apparatus and Infinite Focus Microscopy. High temperature storage tests were carried out to investigate the extent of intermetallic diffusion between the nickel and copper layers. The results show that heat spreaders with thin nickel-copper strike catalytic activation technique have a lower thermal diffusivity due to the low thermal conductivity of nickel-copper layer. Moreover, the nickel-copper layers grew thicker from around 0.2 lm at initial time to around 0.55 lm after high temperature storage duration of 168 h. On the other hand, heat spreaders processed using the galvanic initiation technique did not form any nickel-copper intermetallic diffusion layer. As a conclusion, the galvanic initiation technique can potentially provide better thermal performance for heat spreaders used in semiconductor packages.

The occurrence of galvanism with its heterogeneous symptomatology is often the source of considerable problems. Abrasion and corrosion not only damage dental alloys but also burden the organism by release of metallic particles. The objective of this study is to evaluate the hypothesis that measurement of galvanic currents could be a useful diagnostic method. PATIENT GROUPS AND METHODOLOGY: Three hundred fifty-seven persons with dental metal restorations were divided into groups according to abnormal values of galvanic currents and by oral discomfort. In all persons a detailed examination of the oral cavity was performed, and galvanic currents were measured. In one hundred fifty-nine patients abnormal galvanic currents were found. Measurement of metallic elements in saliva was performed in these patients and in a group of 21 healthy volunteers without any metals in the oral cavity. Thirty-three patients agreed to treatment which involved removal of the causative alloys and their repl...

BACKGROUND: An enhanced release of metals in the mouth due to galvanic cell formation is considered to be one of the causes of oral discomfort. The aim of this study was to investigate the influence of galvanic cell on salivary immune defense factors. The levels of IgA1, IgA2, sIgA, lysozyme and antiIgA/ HSP60 were evaluated in representative samples from 159 patients with galvanism, from 177 patients without galvanism and in two control groups. All the participants underwent personal history taking, clinical examination, galvanic currents measurement and saliva collection. RESULTS: Electro active dental materials were removed in 30 patients. There was a significant increase in IgA2 level, a significant decrease in antiIgA/HSP60 levels and an increase in IgA1, sIgA and lysozyme levels found after the removal of electro active restorations. Morphological symptoms disappeared in 70% of the treated patients. The study confirmed that pathologic galvanic phenomena influences the immune defense reactions in the oral cavity and thus may cause the symptoms of oral discomfort. A measurement of the galvanism and a subsequent removal of electro active restorations should become a common therapeutic procedure in the patients with oral discomfort.

Objective. Avoiding the placement of amalgam and noble metal restorations in interproximal contact is recommended due to anticipated galvanic corrosion of the amalgam. There is a similar concern for amalgam/amalgam galvanic couples. It was the objective of this study to determine if an electrically insulating layer forms in the contact area of these galvanic couples. The existence of an electrically insulating layer, which could reduce the galvanic corrosion rate, would be indicated by different corrosion potentials for the two restorations of the couple. Methods. Using a convenience sample of 158 human subjects, corrosion potentials were measured on each restoration of three types of galvanic couples: amalgam/noble metal (n = 8), amalgam/amalgam (n = 93) and noble metal/noble metal (n = 7). Measurements were made with a Ag/AgCl micro-reference electrode and a high impedance voltmeter. All restorations were at least 6 months old. Results. Statistical analysis showed that the mean absolute corrosion potential differences and the simultaneous confidence intervals of the couples were, respectively, amalgam/noble metal: 62 (31) mV and (27, 99) mV, amalgam/amalgam: 11 (14) mV and (7, 15) mV and noble metal/noble metal: 7 (10) mV and (0, 19) mV. Significance. The amalgam/noble metal couples had consistent and mostly large corrosion potential differences between their restorations, which indicated the presence of an electrically insulating layer. An electrically insulating layer was also indicated for the amalgam/amalgam and noble metal/noble metal couples. The layer is probably composed of non-metallic corrosion products, biofilms, and possibly, dental calculus, which could reduce galvanic corrosion rates to small or negligible values.

Objective. Avoiding the placement of amalgam and noble metal restorations in interproximal contact is recommended due to anticipated galvanic corrosion of the amalgam. There is a similar concern for amalgam/amalgam galvanic couples. It was the objective of this study to determine if an electrically insulating layer forms in the contact area of these galvanic couples. The existence of an electrically insulating layer, which could reduce the galvanic corrosion rate, would be indicated by different corrosion potentials for the two restorations of the couple. Methods. Using a convenience sample of 158 human subjects, corrosion potentials were measured on each restoration of three types of galvanic couples: amalgam/noble metal (n = 8), amalgam/amalgam (n = 93) and noble metal/noble metal (n = 7). Measurements were made with a Ag/AgCl micro-reference electrode and a high impedance voltmeter. All restorations were at least 6 months old. Results. Statistical analysis showed that the mean absolute corrosion potential differences and the simultaneous confidence intervals of the couples were, respectively, amalgam/noble metal: 62 (31) mV and (27, 99) mV, amalgam/amalgam: 11 (14) mV and (7, 15) mV and noble metal/noble metal: 7 (10) mV and (0, 19) mV. Significance. The amalgam/noble metal couples had consistent and mostly large corrosion potential differences between their restorations, which indicated the presence of an electrically insulating layer. An electrically insulating layer was also indicated for the amalgam/amalgam and noble metal/noble metal couples. The layer is probably composed of non-metallic corrosion products, biofilms, and possibly, dental calculus, which could reduce galvanic corrosion rates to small or negligible values.

Recently, research has been more and more preferably focused on the elaboration of the adjustability of shape, size, and surface properties of the colloidal nanostructures in the course of preparation. Relatively uniform hollow nanostructures can be prepared based on well controlled template nanostructures. Thanks to their modifiable optical properties, 3 increased surface and low density, nanostructures with hollow textures have received outstanding attention in the last decades. Because their properties are different from those of the solid structures, they provide new possibilities for developing novel materials in application fields such as biomedical imaging, 4 optical sensors, 5 catalysis, 6,7 supported drug agents, 8 photothermal therapy, 9 and as building elements applicable in the field of ultralight structure materials. 10À12 Unlike monometallic nanostructures, bimetallic ones exhibit properties that make the formation of new applications possible within one single nanostructure. To demonstrate this possibility, reference is made to the alloy brought about by combining gold and silver in nanostructures leading to favorable optical and catalytic properties at the same time. 13À15 The outstanding properties in catalytic processes, stability at high temperatures, and resistance against both physical and chemical impacts make the platinum group metals quite

We demonstrate a simple method for the synthesis of nanoporous metal (Au, Pt, and Pd) rods by the galvanic exchange reaction using Ni as a sacrificial template. Nickel nanorods, prepared by electrodeposition inside porous alumina membrane, were converted to various nanoporous metallic structures by dispersing them in metal salt solutions of the respective metals that are galvanically exchanged. The catalytic activity of the porous Pt and Pd nanorods in the hydrogenation of ethylene was comparable to supported Pt and Pd nanoparticles. The porous nanorods provide a new form of unsupported catalysts in contrast to traditional supported nanoparticle catalysts and can be synthesized in uniform sizes and separated easily from the reaction mixtures without aggregation.

Dissimilar metal joints such as aluminum-steel joints are extensively used in automobile, naval and aerospace applications and these are subjected to corrosive environmental and mechanical loading resulting in eventual failure of the structural joints. In the case of aluminum alloys under aggressive environment, the damage accumulation is predominantly due to corrosion and is accelerated in presence of other metals. During recent years several approaches have been employed to develop models to assess the metal removal rate in the case of galvanic corrosion. Some of these models are based on empirical methods such as regression analysis while others are based on quantification of the ongoing electrochemical processes. Here, a numerical model for solving the Nernst-Planck equation, which captures the electrochemical process, is implemented to predict the galvanic current distribution and, hence, the corrosion rate of a galvanic couple. An experimentally validated numerical model for an AE44 (Magnesium alloy) and mild steel galvanic couple, available in the literature, is extended to simulate the mechanoelectrochemical process in order to study the effect of mechanical loading on the galvanic current density distribution and corrosion rate in AE44-mild steel galvanic couple through a multiphysics field coupling technique in COMSOL Multiphysics®. The model is capable of tracking moving boundariesy of the corroding constituent of the couple by employing Arbitrary Langrangian Eulerian (ALE) method. Results show that, when an anode is under a purely elastic deformation, there is no apparent effect of mechanical loading on the electrochemical galvanic process. However, when the applied tensile load is sufficient to cause a plastic deformation, the local

A theoretical model has been developed to evaluate transport processes and chemical reactions in crevices. The model is general in form, allowing applications to a variety of systems; even including 4 component stainless steel (e.g. alloy 316L). The model has been applied to recent experimental data and other simulated data on crevice corrosion in Fe-Cr alloys. The model considers the time evolution of the solution chemistry and electro-chemistry within crevices, and uses the method of finite elements to solve the complex set of mass-conservation equations describing the system. Activity is corrected in this model because relatively high current densities of Fe-Cr alloys cause high ionic strength in the crevice solution. The results of the model are a little different from those of Sharland model, but both simulated results are reasonable compared with the experimental results.

The sizable potential difference between the crevice mouth and the crevice tip is difficult to explain from theories mainly based on the chemical changes in crevice solution. In this study, the IR drop theory was adopted to explain the initiation of crevice corrosion in the framework of IR drop in the crevice electrolyte. Furthermore, the parameters linking the two components of potential drop -one due to accumulated charges from chemical changes of ionic species by mass transfer and the physical one caused by the current path through the crevice electrolyte -are examined. The mathematical model is constructed and the IR drop in the crevice is calculated using the FVM method. The chemical composition change in the crevice solution can affect the IR drop behavior through the intermediate parameter form of ion conductivity and viscosity, etc., together with the potential difference generated by the electric charge of locally charged ions. Viewed in this light, it can be concluded that the initiation mechanism only by IR drop is insufficient to explain the initiation of crevice corrosion in stainless steels that have very strong passivity.

This paper presents Fibre Reinforced Polymer (FRP) as a third alternative construction material worth considering when retrofitting a bridge structure. FRP offers the following advantages: lighter than steel and concrete, non-corrosive, low in maintenance, stronger than structural steel and fatigue resistant. FRP has been used in Europe and more specifically in the Netherlands for almost 20 years in the retrofitting of road bridges, in new pedestrian bridges, road bridges and lock doors for sluices. The Netherlands has recently developed the updated Dutch Design Code CUR Recommendation 96, which was published in December 2017. The CUR Recommendation 96 will form the basis for developing the Eurocode FRP which is expected to be published between 2020 and 2025. The use of FRP in retrofitting of bridges is presented using examples which demonstrate how existing concrete decks, and steel and concrete substructures could be retained by the use of FRP in the retrofitting solution. Due to ...

Large military vehicles within museum collections are stored in two distinct environments, controlled and uncontrolled, with an intermittent transitional mode where vehicles travel between the two. Variable environmental conditions combined with operational factors pose significant risks to the reliability, durability and longevity of these vehicles. Although there are methods for retarding or decelerating aspects of failure, to maintain the integrity and originality of these vehicles as artefacts a sustainable methodology for conserving these vehicles should be developed. Corrosion is one of the significant contributors to the structural damage and material aging of historical military vehicles; therefore an experimental study was conducted to understand the prevailing mechanisms of failures due to corrosion with various types occurring in these vehicles identified. This paper presents various modes of corrosion in historic vehicles while X-ray Fluorescence and ultrasonic scanning corrosion mapping techniques characterise corrosion inhibiting materials and subsequent material loss. Understanding material profiles and their link to environmental exposure during use and non use of these vehicles will lead to a sustainable methodology for their conservation.

In this communication, the synthesis of nanoparticles on anionic exchange polymers by the Intermatrix Synthesis method is reported. Monometallic (Ag) and core-shell metal/metal oxide (Ag@Fe 3 O 4 ) nanocomposites were synthesized and characterized. Their magnetic and bactericidal activities were evaluated.

Electrodeposited palladium was used as an electrocatalyst for electrochemical oxidation of hydrazine and methanol and the development of a sensitive platform for their detection. The electrochemical behavior of the electrode was evaluated by cyclic voltammetry (CV) while electroanalytical properties were determined by means of differential pulse voltammetry (DPV). The electrodeposited Pd catalyst exhibited good electrocatalytic activity towards the oxidation of hydrazine in neutral solution and methanol oxidation in alkaline solution. Under optimized DPV conditions, the electrodeposited Pd electrode shows good sensing capability in hydrazine and methanol detection.

Here we report a three-dimensional paper fluidic device configured for electrochemical detection of biomolecules labeled with silver nanoparticles (AgNPs). This new sensor, which we call a NoSlip, represents a major improvement of our previously reported oSlip system. Specifically, detection of AgNPs in the NoSlip is based on galvanic exchange rather than a chemical oxidant (bleach or MnO 4 -in the oSlip). Galvanic exchange is implemented by depositing a very small amount of gold onto the working electrode. Once the AgNP labels are brought into the proximity of the electrode through the use of magnetic force, a fraction of the Au 0 is electrochemically oxidized to Au 3+ . The Au 3+ reacts with the AgNPs to form Ag + and Au 0 . The Ag + is then detected by anodic stripping voltammetry. This new methodology resolves three shortcomings of the oSlip while simultaneously simplifying the basic sensor form factor. First, the NoSlip resolves an oxidant instability issue because of the inherent stability of the Au 0 coating on the electrode that is used to electrogenerate the oxidant (Au 3+ ). Additionally, Au 3+ is a milder oxidizing agent than bleach or MnO 4 -, so it does not attack the major components of the NoSlip. Finally, the NoSlip eliminates the need for a slip layer because the oxidant (Au 3+ ) is electrogenerated on demand. The NoSlip is able to detect AgNP labels down to concentrations as low as 2.1 pM, the time to result is ∼7 min, and the cost at the laboratory scale, not including application-specific reagents, is $0.30.

Here we report on the seemingly simple process of galvanic exchange (GE) between electrogenerated AuCl 4 -and silver nanoparticles (AgNPs). The results were obtained in the specific context of using AgNPs as labels for bioassays in paper fluidic devices. Results obtained from a combined electrochemistry and microscopy study indicate that the GE process results in recovery of only ~5% of the total equivalents of Ag present in the system. This low value is a consequence of two factors. First, after an initial fraction of each AgNP undergoes GE, a Au shell forms around the remaining AgNP core preventing further exchange. Second, to simulate a true biological fluid, the experiments were carried out in a Cl --containing buffer. Consequently, some Ag + formed during GE precipitates as AgCl, and it also serves to block additional GE. Following optimization of the GE process, it was possible to detect AgNP label concentrations as low as 2.6 fM despite these limitations.

Here we report on the seemingly simple process of galvanic exchange (GE) between electrogenerated AuCl 4 -and silver nanoparticles (AgNPs). The results were obtained in the specific context of using AgNPs as labels for bioassays in paper fluidic devices. Results obtained from a combined electrochemistry and microscopy study indicate that the GE process results in recovery of only ~5% of the total equivalents of Ag present in the system. This low value is a consequence of two factors. First, after an initial fraction of each AgNP undergoes GE, a Au shell forms around the remaining AgNP core preventing further exchange. Second, to simulate a true biological fluid, the experiments were carried out in a Cl --containing buffer. Consequently, some Ag + formed during GE precipitates as AgCl, and it also serves to block additional GE. Following optimization of the GE process, it was possible to detect AgNP label concentrations as low as 2.6 fM despite these limitations.

Here we report a three-dimensional paper fluidic device configured for electrochemical detection of biomolecules labeled with silver nanoparticles (AgNPs). This new sensor, which we call a NoSlip, represents a major improvement of our previously reported oSlip system. Specifically, detection of AgNPs in the NoSlip is based on galvanic exchange rather than a chemical oxidant (bleach or MnO 4 -in the oSlip). Galvanic exchange is implemented by depositing a very small amount of gold onto the working electrode. Once the AgNP labels are brought into the proximity of the electrode through the use of magnetic force, a fraction of the Au 0 is electrochemically oxidized to Au 3+ . The Au 3+ reacts with the AgNPs to form Ag + and Au 0 . The Ag + is then detected by anodic stripping voltammetry. This new methodology resolves three shortcomings of the oSlip while simultaneously simplifying the basic sensor form factor. First, the NoSlip resolves an oxidant instability issue because of the inherent stability of the Au 0 coating on the electrode that is used to electrogenerate the oxidant (Au 3+ ). Additionally, Au 3+ is a milder oxidizing agent than bleach or MnO 4 -, so it does not attack the major components of the NoSlip. Finally, the NoSlip eliminates the need for a slip layer because the oxidant (Au 3+ ) is electrogenerated on demand. The NoSlip is able to detect AgNP labels down to concentrations as low as 2.1 pM, the time to result is ∼7 min, and the cost at the laboratory scale, not including application-specific reagents, is $0.30.

Reliable detection of specific antibodies against pathogens by lateral flow immunoassay (LFIA) greatly depends on the composition of the detectable complex and the order of its assembly. We compared three LFIA formats for revealing anti-SARS-CoV-2 antibodies in sera with the following detected complexes in the analytical zone of the strip: antigen–antibodies–labeled immunoglobulin-binding protein (Scheme A); antigen–antibodies–labeled antigen (Scheme B); and immunoglobulin-binding protein–antibodies–labeled antigen (Scheme C). The lowest detection limit was observed for Scheme C, and was equal to 10 ng/mL of specific humanized monoclonal antibodies. When working with pooled positive sera, Scheme C had a detection limit 15 times lower than Scheme B and 255 times lower than Scheme A. Due to the high sensitivity of Scheme C, its application for the panel of human sera (n = 22) demonstrated 100% diagnostic specificity and sensitivity. These consistent results be useful for designing the...

Heavy metal pollution is still of actual task despite on many developments. The growth in nanotechnology allowed for application of nanoparticles modified with receptor molecules for selective or group-selective recognition of concrete metal ions. One of these molecules are aptamers which consist of nucleotides linked in necessary order. In our investigation new aptamer-based assay format for mercury ions has been developed. It is based on lateral flow technique with working nitrocellulose membrane and immobilized reagents as corresponding test zones. Two reagents have been applied to form the detectable complex on the membrane. Conjugate of bovine serum albumin with glutathione was immobilized on the nitrocellulose membrane to form the test zone as catching agent. Freshly prepared gold nanoparticles were conjugated with G,T-rich oligonucleotide as recognition agent. A linear relationship between the change in the color intensity of the corresponding test zones and the concentration of H g2+ ions in the range from 5 to 1000 ng/mL was observed. Visual limit of mercury detection was of 10 ng/mL. Total duration of the analysis is 5 min. Thus, the developed technique is promising for Hg 2+ detection in different water sources to confirm their safety.

The requirement for lighter vehicles in the automotive industry promotes designs based on the combination of different metallic alloys. Such an approach, however, leads to galvanic-corrosion risks, which compromise the durability of vehicles. One proposal to minimize such risks is to separate some of the chassis components by a Zn washer. The present work uses the finite element method to evaluate such an innovative design. The capacity of the washer to protect its aluminum alloy and carbon steel neighbors is assessed. As a worst-case scenario, the bare metals are in contact with NaCl solution. Two electrolyte layer thicknesses are assumed: in the micrometer and in the millimeter range. Each case requires different mathematical models. For the thin film case, the zinc washer is able to protect its neighbors from corrosion. However, it sustains large corrosion rates, and thus its protection is effective only during short periods. Furthermore, as the Zn surface degrades and thus recesses, the "protective field" is blocked by the neighboring metal-walls. The thicker the electrolyte layer, the weaker the Zn protective capability and, at some point, the corrosion of the aluminum alloy is unavoidable.

The galvanic industry and the production of printed circuit boards are a significant source of environmental pollution, they pose a threat comparable to the chemical industry. They pollute both the atmosphere, the biosphere and the hydrosphere. The paper presents an assessment of the negative impact on the environment, galvanic production and the resulting post-production waste. It was proposed to use the technology of regeneration of used treating solutions, in which the recovered metal can be reused as a secondary raw material for the production of copper products. The regenerated solution, on the other hand, can be used to treat integrated circuit boards. As part of the work, with the use of a microscope, the structural characteristics of the metal surface obtained as a result of the applied regeneration process were carried out. The indicator of the total exposure to substances present in the deposit formed during production was determined, both before (0.045) and after the introduction of the new technology (100). The economic analysis of the planned project based on the new technology showed that the implementation of the presented method of wastewater treatment allows for obtaining significant benefits, both financial and environmental. The analyses performed can be a valuable source of information on how to reduce the impact environment during the production of integrated circuit boards, as well as on the possibilities of obtaining less expensive materials in the form of secondary raw materials.

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – var...

Cathodic protection (CP) is a technique that prevents corrosion of underground metallic structures. Design of any CP system first requires defining the protection of current density and potential distribution, which should meet the given criterion. It also needs to provide, as uniform as possible, current density distribution on the protected object surface. Determination of current density and potential distribution of CP system is based on solving the Laplace partial differential equation. Mathematical model, along with the Laplace equation, is represented by two additional equations that define boundary conditions. These two equations are non-linear and they represent the polarization curves that define the relationship between current density and potential on electrode surfaces. Nowadays, the only reliable way to determine current density and potential distribution is by applying numerical techniques. This paper presents efficient numerical techniques for the calculation of current density and potential distribution of CP system based on the coupled boundary element method (BEM) and finite element method (FEM).

This paper considers the effect of discontinuity of electrical conductivity of electrolytes on the distribution of potential and protective current density in cathodic protection systems with galvanic anodes. The aim of the paper is to present a simultaneous analysis for application of both analytical and numerical models for calculation of the distribution of protective potential and current density in the cases of homogeneous and double-layer electrolytes. When considering non-linear boundary conditions at the electrode surface (secondary distribution of protective current density), the indirect boundary element method is used, because of the complexity of the calculation. Collocation at the point method was used for calculation. Due to the nonlinearity of boundary conditions at the electrode surfaces, the calculation problem is further complicated. In order to show the importance of this analysis, calculations for the observed system as well as calculations of errors caused by neglecting the boundary discontinuity of the soil conductivity are provided. Based on calculations and with respect to error analyses, the conclusive remark gives the impact valuation of the doublelayer electrolyte on the correct calculation of the cathodic protection system with galvanic anodes. This paper also gives the analysis when the double-layered nature of the electrolyte can practically be ignored, which has great importance for designers of these systems.

Several useful properties and parameters-a model of the regional mean one-dimensional (1D) conductivity profile, local and regional distortion indicators, and apparent gains-were defined in our recent paper using two rotational invariants (det: determinant and ssq: sum of squared elements) from a set of magnetotelluric (MT) data obtained by an array of observation sites. In this paper, we demonstrate their characteristics and benefits through synthetic examples using 1D and three-dimensional (3D) models. First, a model of the regional mean 1D conductivity profile is obtained using the average ssq impedance with different levels of galvanic distortion. In contrast to the Berdichevsky average using the average det impedance, the average ssq impedance is shown to yield a reliable estimate of the model of the regional mean 1D conductivity profile, even when severe galvanic distortion is contained in the data. Second, the local and regional distortion indicators were found to indicate the galvanic distortion as expressed by the splitting and shear parameters and to quantify their strengths in individual MT data and in the dataset as a whole. Third, the apparent gain was also shown to be a good approximation of the site gain, which is generally claimed to be undeterminable without external information. The model of the regional mean 1D profile could be used as an initial or a priori model in higher-dimensional inversions. The local and regional distortion indicators and apparent gains could be used to examine the existence and to guess the strength of the galvanic distortion. Although these conclusions were derived from synthetic tests using the Groom-Bailey distortion model, additional tests with different distortion models indicated that these conclusions are not strongly dependent on the choice of distortion model. These galvanic-distortion-related parameters would also assist in judging if a proper treatment is needed for the galvanic distortion when an MT dataset is given. Hence, this information derived from the dataset would be useful in MT data analysis and inversion.

Environmental regulations limit the presence of copper in the wastewater from industries to 3 mg/l; furthermore, copper is a rather expensive commodity. Consequently, recovery of this metal is both necessary and attractive. Electrowining techniques are commonly used to recover copper, but it cannot be used when the streams contain hydrocarbons such as the waste stream, Multibond, from company A. As a result, this company is force to send their waste stream abroad for treatment paying 1.32 Euro/kg of waste. The present project aims to recover copper via a hydrothermal process in the form of (99% pure) copper metal powder that can be sold to scrap industries in the area. The copper reduction will be achieved by combining a copper sulphate solution (copper II) waste stream and a carbohydrate waste stream under 12 bar and 185 o C in a Kenics static mixer. The accessibility and the low or no-price for the feedstocks, make this design even more attractive. The copper reduction plant consists mainly of two units: reaction and separation. Thus making it a very simple process. Furthermore, the recovery is >99% copper. This process has already been made a reality in countries such as Chile where copper is abundant and the main export commodity. Currently new sites for this process are being developed and have been patented around the world.