Characterization of Ag/AgCl Dry Electrodes for Wearable Electrophysiological Sensing

With the rising need for on-body biometric sensing, the development of wearable electrophysiological sensors has been faster than ever. Surface electrodes placed on the skin need to be robust in order to measure biopotentials from the body reliably and comfortable for extended wearability. The electrical stability of nonpolarizable silver/silver chloride (Ag/AgCl) and its low-cost, commercial production have made these electrodes ubiquitous health sensors in the clinical environment, where wet gels and long wires are accommodated by patient immobility. However, smaller, dry electrodes with wireless acquisition are essential for truly wearable, continuous health sensing. Currently, techniques for the robust fabrication of custom Ag/AgCl electrodes are lacking. Here, we present three methods for the fabrication of Ag/AgCl electrodes: oxidizing Ag in a chlorine solution, electroplating Ag, and curing Ag/AgCl ink. Each of these methods is then used to create three different electrode shapes for wearable application. Bench-top and on-body evaluation of the electrode techniques was achieved by electrochemical impedance spectroscopy (EIS), calculation of variance in electrocardiogram (ECG) measurements, and analysis of auditory steady-state response (ASSR) measurement. Microstructures produced on the electrode by each fabrication technique were also investigated with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The custom Ag/AgCl electrodes were found to be efficient in comparison with standard, commercial Ag/AgCl wet electrodes across all three of our presented techniques, with Ag/AgCl ink shown to be the better out of the three in bench-top and biometric recordings.

Scientific Analysis and Conservation Treatment on the Buddhist Scriptures of Paper Relics Excavated from Sum Tolgoi, Mongolia

This study analyzed the composition and structure of materials with Buddhist paper scriptures excavated from architectural sites in ‘Sum Tolgoi’ of the 17th century and carried out conservation treatment base on the result of the analysis. The scriptures were covered in dust and foreign sub stances, and were so crumpled that it was impossib le to identify the form. The damage, loss, and discoloration have been identified. Buddhist scriptures written in Tibetan used indigo and ink sticks on paper as a result of UV-Vis analysis, and ink sticks as black character materials from scriptures written ancient Mongolian. SEM-EDS and Micro-XRF analyses revealed that the outlines were drawn with red lines using a mix of Minium (Pb3O4) and Cinnabar (HgS), or Cinnabar (HgS) alone, and the contents of the scriptures were written with silver paint. Silver chloride (AgCl) and Calcium (Ca) were identified in the silver paint component of the characters, while Calcium and Orpiment (As2S3) were identified in the yellow lines. Concerning the paper ground, Buddhist scriptures written in ancient Mongolian were characterized by herbal plant fiber and bast fiber, and those written in Tibetan, by bast fiber. Radiocarbon dating indicates that the paper for the scriptures was produced b etween the 15th and 17th centuries. Conservation treatment of the scriptures was carried out based on the experiment on the production of pre-coated paper and how to coat that to prevent the second damage due to the deformation and fragility of the excavated paper. The scriptures were preserved and mounted, and a neutral box was made to identify the contents of the scriptures recorded on both sides after the treatment. This conservation treatment is the result of a study that applied new conservation treatment materials and methods according to the principle of conservation treatment reversibility.

Biosynthesis of Silver Chloride Nanoparticles by Rhizospheric Bacteria and Their Antibacterial Activity against Phytopathogenic Bacterium Ralstonia solanacearum

Ralstonia solanacearum is the most destructive pathogen, causing bacterial wilt disease of eggplant. The present study aimed to develop green synthesis and characterization of silver chloride nanoparticles (AgCl-NPs) by using a native bacterial strain and subsequent evaluation of their antibacterial activity against R. solanacearum. Here, a total of 10 bacterial strains were selected for the biosynthesis of AgCl-NPs. Among them, the highest yield occurred in the synthesis of AgCl-NPs using a cell-free aqueous filtrate of strain IMA13. Ultrastructural observation revealed that the AgCl-NPs were spherical and oval with smooth surfaces and 5–35 nm sizes. XRD analysis studies revealed that these particles contained face-centered cubic crystallites of metallic Ag and AgCl. Moreover, FTIR analysis showed the presence of capping proteins, carbohydrates, lipids, and lipopeptide compounds and crystalline structure of AgCl-NPs. On the basis of phylogenetic analysis using a combination of six gene sequences (16S, gyrA, rpoB, purH, polC, and groEL), we identified strain IMA13 as Bacillus mojavensis. Three kinds of lipopeptide compounds, namely, bacillomycin D, iturin, and fengycin, forming cell-free supernatant produced by strain IAM13, were identified by MALDI-TOF mass spectrometry. Biogenic AgCl-NPs showed substantial antibacterial activity against R. solanacearum at a concentration of 20 µg/mL−1. Motility assays showed that the AgCl-NPs significantly inhibited the swarming and swimming motility (61.4 and 55.8%) against R. solanacearum. Moreover, SEM and TEM analysis showed that direct interaction of AgCl-NPs with bacterial cells caused rupture of cell wall and cytoplasmic membranes, as well as leakage of nucleic acid materials, which ultimately resulted in the death of R. solanacearum. Overall, these findings will help in developing a promising nanopesticide against phytopathogen plant disease management.

Indirect Electrochemical Determination of Chlorpropamide Through Its Interaction with Valsartan Using Square Wave Voltammetry

A square wave voltammetric technique coupled with three electrode detection system consist of hanging mercury drop electrode (HMDE) as working electrode, 1mm platinum wire as an auxiliary electrode (Pt-wire) and silver/silver chloride saturated potassium chloride (Ag/AgCl.sat.KCl) as reference electrode was used to determine the chlorpropamide indirectly through its interaction with valsartan, chlorpropamide gives no reduction peaks in the studied range. The effect of pH and the stability of the measurement were examined calibrations curve of chlorpropamide was constructed and the relation between current and concentration of chlorpropamide was linear with R2 value = 0.9944. The limit of detection for chlorpropamide was 4.89 x 10-9 M through its interaction with valsartan.

On problem of using copper electrodes to maintain protection against corrosion of steel hulls of ships and vessels

The paper focuses on the reasons for the lack of proper control of the operation of the electrochemical protective systems of sea vessels, such as the absence of convenient technical equipment, primarily the reference electrodes, as well as the imperfection of the silver chloride reference electrode. There is considered the approach to the development of easy-to-use reference electrodes. A standard silver chloride reference electrode was used as the first electrode; experimental electrodes made of a copper wire strand stripped of insulation were used as the second and third electrodes. The experimental vessel is docked in the commercial port of Petropavlovsk-Kamchatsky. The corrosion protection of the ship’s hull was evaluated by measuring the potentials between the metal hull and the reference electrode at a given point. The measurements were performed at a time interval from 06/10/2021 to 06/18/2021, evaluating the control of the hull corrosion protection was made by taking 50 successive measurements, which were entered into the control tables. It has been stated that the results of ship’s hull sacrificial protection control by using experimental copper electrodes from cabling comply with the regulatory requirements. The ship’s crew didn’t have any financial, organizational or technical problems, which could usually arise from the operation of standard silver chloride reference electrodes. It has been inferred that using regulated and non-regulated electrodes in the organization of corrosion control on ships and metal offshore structures is possible.

Multifunctional Textiles from New Zealand Wool Coloured with Silver or Silver Halide Nanoparticles

<p>Significant opportunities exist for the development of innovative multifunctional textiles for high value market applications. Composites that combine the inherent properties of their all precursor components in a synergistic manner in particular are sought after. Thus the unique chemical and physical properties of silver or silver halide nanoparticles are combined with the traditional properties of wool, thereby producing an innovative multifunctional composite. The prepared wool - silver or - silver halide nanoparticle composites retain the elasticity, thermal insulation and softness of the wool, whilst the colour, conductivity and antimicrobial properties owing to the nanoparticles are also incorporated. Due to the multi functions of silver the resulting high quality, high value product has numerous applications within the fashion and interior furnishings industries. The wools employed for the preparation of wool - silver or - silver chloride nanoparticle composites are merino wool and crossbred wool. Merino wool provides the main focus of the research. The experimental approach for the colouring of merino by silver or silver halide nanoparticles follows a novel and proprietary approach. The preparation of wool - silver nanoparticle composites includes two different procedures: 1) the synthesis of nanoparticles in the presence of wool fibres, using an external reducing agent/stabilising agent (trisodium citrate (TSC)), with the in situ binding of nanoparticles to the surface of the fibre; and 2) the synthesis of nanoparticles in the presence of the merino wool substrate, using the reducing nature of wool, with the in situ binding of nanoparticles within the fibre. Merino wool - silver nanoparticle composites range in colour from very pale yellow, through gold to tan and brown. The successful preparation of wool - silver halide nanoparticle composites includes the in situ precipitation of nanoparticles within the wool fibre. This is accomplished by doping the wool, with one of the halides, Cl⁻, Br⁻ or I⁻, prior to treatment with a silver containing solution. The colour of merino wool - silver halide nanoparticle composites can be tuned from pink to peach to purple. The colour of the wool - silver or - silver halide nanoparticle composites is due to surface plasmon resonances, i.e. the interaction of electromagnetic radiation of visible light with the nanoparticles. The reflected colour is dependent upon the size and shape of the nanoparticle, in addition to the refractive index of the stabilising agent surround the particle. The refractive index of silver chloride or silver bromide differs to that of the reducing/stabilising agent implemented, TSC, or merino, and thus the reflected colour is altered. The colour of silver iodide nanoparticles appears to be due to the interaction of light with the formed nanoparticles themselves and not due to the formation of silver nanoparticles within the silver iodide nanoparticles. In addition to the colour being measured by UV-vis in reflectance mode, the characterisation of the hues of the prepared composites were monitored by obtaining CIE L*, a*, b* values via the HunterLab Colourquest. The morphological characterisation of merino wool coloured by silver or silver chloride nanoparticles was undertaken using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). When merino wool - silver nanoparticle composites are prepared using an external reducing agent, the formed nanoparticles predominantly bind to the wool fibres surfaces only. When the reducing nature of wool is used for composite preparation, nanoparticles are formed within the fibre and are dispersed throughout the fibres core, with few being present on the surface. Comparable studies of merino wool - silver halide nanoparticle composites showed that silver halide nanoparticles are formed and stabilised just below the fibres surface. The confirmation of silver or silver halide species within the prepared composites was undertaken using energy dispersive spectroscopy (EDS), scanning transmission spectroscopy (STEM), x-ray diffraction (XRD) and x-ray absorption near edge spectroscopy (XANES). Colourfastness tests to washing, rubbing and exposure to chlorinated swimming pool water were undertaken to assess the robustness of the prepared composites in terms of their colour. These tests indicate that the colours of both merino wool - silver and - silver chloride nanoparticle composites are very stable. The leaching of silver during the washing process was noted to be insignificant, suggesting a strong and stable bond between the fibre substrate and the nanoparticles. X-ray photoelectron spectroscopy (XPS) was used to elucidate the chemical bonding between the wool fibre substrate and the silver or silver halide nanoparticles. The colourfastness of merino wool - silver or - silver halide nanoparticle composites to light however, was not observed. When exposed to UV light for extended periods, a distinct change in colour occurs. Silver nanoparticle composites lighten considerably, whereas their silver chloride nanoparticle counterparts are noted to become grey in their colour. XPS was used in an attempt to determine what leads to the discolouration of the composites. Further research is required however, in order to reduce or halt the colour degradation of merino wool - silver or - silver chloride nanoparticle composites. Silver iodide nanoparticles, on the other hand, show great potential as colourants for wool, exhibiting stable colours over a long time period to light. A range of desirable colours are obtained through the colouring of wool by silver or silver halide nanoparticles. These nanoparticles are strongly bound to the fibres and thus the colours are stable to washing and rubbing, exhibiting insignificant leaching of silver during such processes. Additionally, the prepared silver and silver halide nanoparticle composites tested positive for their antistatic properties, and their antimicrobial activity, providing a high value multifunctional material. Numerous applications within fashion and interior furnishing industries are therefore apparent. However, the evident setback for applications in these fields is the colour instability to light of silver, silver chloride and silver bromide nanoparticles, and thus further studies are required to eliminate this problem. Alternative options exist for the exploitation of the photosensitivity of silver halide nanoparticles within the merino wool composites, or the possibility of using silver or silver halide nanoparticles in combination with other strong dyes for the production of coloured woollen fabrics.</p>

Multifunctional Textiles from New Zealand Wool Coloured with Silver or Silver Halide Nanoparticles

<p>Significant opportunities exist for the development of innovative multifunctional textiles for high value market applications. Composites that combine the inherent properties of their all precursor components in a synergistic manner in particular are sought after. Thus the unique chemical and physical properties of silver or silver halide nanoparticles are combined with the traditional properties of wool, thereby producing an innovative multifunctional composite. The prepared wool - silver or - silver halide nanoparticle composites retain the elasticity, thermal insulation and softness of the wool, whilst the colour, conductivity and antimicrobial properties owing to the nanoparticles are also incorporated. Due to the multi functions of silver the resulting high quality, high value product has numerous applications within the fashion and interior furnishings industries. The wools employed for the preparation of wool - silver or - silver chloride nanoparticle composites are merino wool and crossbred wool. Merino wool provides the main focus of the research. The experimental approach for the colouring of merino by silver or silver halide nanoparticles follows a novel and proprietary approach. The preparation of wool - silver nanoparticle composites includes two different procedures: 1) the synthesis of nanoparticles in the presence of wool fibres, using an external reducing agent/stabilising agent (trisodium citrate (TSC)), with the in situ binding of nanoparticles to the surface of the fibre; and 2) the synthesis of nanoparticles in the presence of the merino wool substrate, using the reducing nature of wool, with the in situ binding of nanoparticles within the fibre. Merino wool - silver nanoparticle composites range in colour from very pale yellow, through gold to tan and brown. The successful preparation of wool - silver halide nanoparticle composites includes the in situ precipitation of nanoparticles within the wool fibre. This is accomplished by doping the wool, with one of the halides, Cl⁻, Br⁻ or I⁻, prior to treatment with a silver containing solution. The colour of merino wool - silver halide nanoparticle composites can be tuned from pink to peach to purple. The colour of the wool - silver or - silver halide nanoparticle composites is due to surface plasmon resonances, i.e. the interaction of electromagnetic radiation of visible light with the nanoparticles. The reflected colour is dependent upon the size and shape of the nanoparticle, in addition to the refractive index of the stabilising agent surround the particle. The refractive index of silver chloride or silver bromide differs to that of the reducing/stabilising agent implemented, TSC, or merino, and thus the reflected colour is altered. The colour of silver iodide nanoparticles appears to be due to the interaction of light with the formed nanoparticles themselves and not due to the formation of silver nanoparticles within the silver iodide nanoparticles. In addition to the colour being measured by UV-vis in reflectance mode, the characterisation of the hues of the prepared composites were monitored by obtaining CIE L*, a*, b* values via the HunterLab Colourquest. The morphological characterisation of merino wool coloured by silver or silver chloride nanoparticles was undertaken using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). When merino wool - silver nanoparticle composites are prepared using an external reducing agent, the formed nanoparticles predominantly bind to the wool fibres surfaces only. When the reducing nature of wool is used for composite preparation, nanoparticles are formed within the fibre and are dispersed throughout the fibres core, with few being present on the surface. Comparable studies of merino wool - silver halide nanoparticle composites showed that silver halide nanoparticles are formed and stabilised just below the fibres surface. The confirmation of silver or silver halide species within the prepared composites was undertaken using energy dispersive spectroscopy (EDS), scanning transmission spectroscopy (STEM), x-ray diffraction (XRD) and x-ray absorption near edge spectroscopy (XANES). Colourfastness tests to washing, rubbing and exposure to chlorinated swimming pool water were undertaken to assess the robustness of the prepared composites in terms of their colour. These tests indicate that the colours of both merino wool - silver and - silver chloride nanoparticle composites are very stable. The leaching of silver during the washing process was noted to be insignificant, suggesting a strong and stable bond between the fibre substrate and the nanoparticles. X-ray photoelectron spectroscopy (XPS) was used to elucidate the chemical bonding between the wool fibre substrate and the silver or silver halide nanoparticles. The colourfastness of merino wool - silver or - silver halide nanoparticle composites to light however, was not observed. When exposed to UV light for extended periods, a distinct change in colour occurs. Silver nanoparticle composites lighten considerably, whereas their silver chloride nanoparticle counterparts are noted to become grey in their colour. XPS was used in an attempt to determine what leads to the discolouration of the composites. Further research is required however, in order to reduce or halt the colour degradation of merino wool - silver or - silver chloride nanoparticle composites. Silver iodide nanoparticles, on the other hand, show great potential as colourants for wool, exhibiting stable colours over a long time period to light. A range of desirable colours are obtained through the colouring of wool by silver or silver halide nanoparticles. These nanoparticles are strongly bound to the fibres and thus the colours are stable to washing and rubbing, exhibiting insignificant leaching of silver during such processes. Additionally, the prepared silver and silver halide nanoparticle composites tested positive for their antistatic properties, and their antimicrobial activity, providing a high value multifunctional material. Numerous applications within fashion and interior furnishing industries are therefore apparent. However, the evident setback for applications in these fields is the colour instability to light of silver, silver chloride and silver bromide nanoparticles, and thus further studies are required to eliminate this problem. Alternative options exist for the exploitation of the photosensitivity of silver halide nanoparticles within the merino wool composites, or the possibility of using silver or silver halide nanoparticles in combination with other strong dyes for the production of coloured woollen fabrics.</p>