Kinetics of hydrogen evolution reaction on Ni-Me-P electrodes

Hydrogen, a wholly non-polluting and renewable fuel, may be obtained by the electrocatalytic hydrogen evolution reaction (HER). Electrocatalytic hydrogen production calls for efficient and durable electrodes by finding the origin of the electrocatalytic activity, and improving the properties. The candidate materials for cathodes are limited. Those that have high surface area suffer from low physical stability and deterioration in long-term operation. If physical stability is improved the activity is decreased. When both properties are improved the production expense is increased. The main purpose of this study is to prepare new electrode materials and study their activity and reaction mechanism for the HER. Three categories of the electrodes of nickel phosphorous family were studied, Ni-P, Ni-Mo-P, and Ni-Zn-P. Ni-P materials are very stable in alkaline solutions. Their stability is better than Ni. Phosphorous is not removed by means of leaching the electrodes in HF, alkaline solutions, heating, and/or oxidation to produce a rough surface. Electrodes prepared at low current densities and temperature were active for the HER due to increase in the surface roughness. The most active Ni-P electrode prepared in this study had a surface roughness of 10[subscript 3] XRD patterns of Ni-P electrodes have amorphous structure. After heating at 400 [degree Celsius] the structure of electrodes changed to crystalline with domination of Ni[subscript 3]P phase (for high phosphorous content electrodes) or Ni[subscript 3]P and Ni (for low phosphorous content electrodes). Ni-Mo-P electrodes were prepared by"multi-step" electrodeposition. The activity of the electrodes was increased through increase in surface roughness as well as intrinsic activity. Cycling of the electrodes between the HER and oxygen evolution reaction (OER) deactivated them. Mo was mostly dissolved during electrooxidation of these materials. Ni-Zn-P electrodes were prepared by subsequent electrodeposition of Ni, Ni-P, and Ni-Zn-P. The top-most layer was obtained by gradual addition of zinc to the plating bath. After leaching the electrodes in 30% KOH, about 80% of Zn was removed leading to a porous surface with a large area with excellent stability. Those prepared at high current densities are the most active ones. They are characterized by low Tafel slopes and large surface area with roughness factor of 10[subscript 4]. Electrochemical impedance spectroscopy (EIS) and steady-state polarization are mainly used to explain activity of the electrodes using real surface area. A new technique for the surface roughness determination i.e.,"CO molecular probe" was developed. Ni-Zn-P porous electrode surface roughness was measured by the EIS and compared with results from surface oxidation, cyclic voltammetry (cv), ratio of the polarization current densities, and CO molecular probe showing good agreement with those obtained by the EIS. Besides, the results show that dissolved CO in NaOH can be oxidized on Ni and Ni-Zn-P electrodes. This is a new observation of CO behavior on nickel based electrodes."--Résumé abrégé par UM

Comparison of the effect of topical application of Eugenia caryophylata extract and topical diclofenac in primary knee osteoarthritis: a clinical trial study

Background and aims: osteoarthritis is one of the most common arthritis in elderly. we evaluated to compare the effect of topical application of Eugenia caryophylata extract and topical diclofenac in primary knee osteoarthritis. Methods: This randomized double-blind clinical trial study was carried out upon 105 patients with primary knee osteoarthritis. Patients were selected randomly and divided into three groups of 35(diclofenac) and 35 (Eugenia caryophylata) and 35(placebo).The first group was given three times diclofenac 1 of one mg, the second group was given topical caryophylata 10 of one mg three times daily and third group was given placebo 1 mg three times daily. For three groups, WOMAC questionnaire (overall pain, knee pain, morning stiffness, stiffness during day, physical activity ) were completed pretreatment, one week and three and four weeks post-treatment. Findings: The findings indicated that there is a significant decrease in overall pain (p=o.oo5), stiffness during day (p=0.001), morning stiffness (p=0.001) and knee pain (p=0.017) and physical activity (p=0.001) in four weeks after the initiation of treatment in three groups of topical Eugenia caryophylata, diclofenac and placebo . In all the three groups, mean overall score of womac questionnaire was significantly decreased .no side effects related to the intake of medication in three groups was observed. Conclusion: Extract of Eugenia caryophylata is effective in decreasing knee pain, morning stiffness, and stiffness during day and improvement of physical activity in patients with knee osteoarthritis and it can be used alongside of chemical medication to reduce symptoms of knee osteoarthritis

A Synthetic Electrocardiogram (ECG) Image Generation Toolbox to Facilitate Deep Learning-Based Scanned ECG Digitization

The electrocardiogram (ECG) is an accurate and widely available tool for diagnosing cardiovascular diseases. ECGs have been recorded in printed formats for decades and their digitization holds great potential for training machine learning (ML) models in algorithmic ECG diagnosis. Physical ECG archives are at risk of deterioration and scanning printed ECGs alone is insufficient, as ML models require ECG time-series data. Therefore, the digitization and conversion of paper ECG archives into time-series data is of utmost importance. Deep learning models for image processing show promise in this regard. However, the scarcity of ECG archives with reference time-series is a challenge. Data augmentation techniques utilizing \textit{digital twins} present a potential solution. We introduce a novel method for generating synthetic ECG images on standard paper-like ECG backgrounds with realistic artifacts. Distortions including handwritten text artifacts, wrinkles, creases and perspective transforms are applied to the generated images, without personally identifiable information. As a use case, we generated an ECG image dataset of 21,801 records from the 12-lead PhysioNet PTB-XL ECG time-series dataset. A deep ECG image digitization model was built and trained on the synthetic dataset, and was employed to convert the synthetic images to time-series data for evaluation. The signal-to-noise ratio (SNR) was calculated to assess the image digitization quality vs the ground truth ECG time-series. The results show an average signal recovery SNR of 27$\pm$2.8\,dB, demonstrating the significance of the proposed synthetic ECG image dataset for training deep learning models. The codebase is available as an open-access toolbox for ECG research

Robots Taking Initiative in Collaborative Object Manipulation: Lessons from Physical Human-Human Interaction

Physical Human-Human Interaction (pHHI) involves the use of multiple sensory modalities. Studies of communication through spoken utterances and gestures are well established. Nevertheless, communication through force signals is not well understood. In this paper, we focus on investigating the mechanisms employed by humans during the negotiation through force signals, which is an integral part of successful collaboration. Our objective is to use the insights to inform the design of controllers for robot assistants. Specifically, we want to enable robots to take the lead in collaboration. To achieve this goal, we conducted a study to observe how humans behave during collaborative manipulation tasks. During our preliminary data analysis, we discovered several new features that help us better understand how the interaction progresses. From these features, we identified distinct patterns in the data that indicate when a participant is expressing their intent. Our study provides valuable insight into how humans collaborate physically, which can help us design robots that behave more like humans in such scenarios

Size and strain dependent activity of Ni nano and micro particles for hydrogen evolution reaction

In the context of constant research for the improvement of alkaline water electrolysis process using advanced electrocatalytic materials for the hydrogen evolution reaction (HER), various nickel particle based electrode materials were prepared and characterized. The synthesis of nickel hydroxide nanoparticles was performed in water in presence of three different stabilizers (CTAB, PVP and KBr). A thermal treatment at 400 °C under 5% H2/Ar atmosphere led to nickel nanoparticles. Mechanically milled commercial micrometric particles and nanoparticles synthesised by a polyol route completed a series of Ni powders showing broad ranges of size (5 nm–73 μm) and strain (6 ppm–0.7%). The electrocatalytic activity of the resulting electrode materials was evaluated versus powder morphology. Their apparent and intrinsic activity and the mechanism of the HER were studied by electrochemical impedance spectroscopy (EIS) and steady-state polarisation. A change in the HER mechanism is observed depending on particle size. This first systematic study demonstrates that the smaller the size and the more defective the particles, the greater the electrocatalytic activity. As a matter of fact, appreciable cathodic current densities of 100 mA cm−2 at ∼ −300 mV of overpotential were obtained for nickel nanoparticles with 5 nm size and 0.7% strain

Enhancement of electrochemical activity of Raney-type NiZn coatings by modifying with PtRu binary deposits: Application for alkaline water electrolysis

This study presents electrochemical preparation and characterization of PtRu-modified Cu/Ni/NiZn electrodes (Cu/Ni/NiZn-PtRu) as cathode materials for alkaline water electrolysis. The electrodes were characterized using energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Their electrochemical activities as cathode materials for alkaline water electrolysis were evaluated with the help of current potential curves. The results showed that the PtRu-modified layers have porous structures with relatively low Pt and Ru chemical compositions. The modification of the alkaline leached Cu/Ni/NiZn surface by Pt and/or Ru enhances the electrochemical activity of the electrode. Their catalytic activity depends on the molar ratios of Pt and Ru; the PtRu binary deposit with the percentage weight ratio of approximately 56:44 exhibits the highest hydrogen evolution activity among the studied electrodes. The enhanced hydrogen evolution activity of the PtRu-modified electrodes was related to the porous surface and/or a possible synergistic effect between the metals. Copyright (c) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Biosensing for the Environment and Defence: Aqueous Uranyl Detection Using Bacterial Surface Layer Proteins

The fabrication of novel uranyl (UO22+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO22+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO22+ binding, showing that both moieties are involved in the recognition to UO22+

Assessment of the roughness factor effect and the intrinsic catalytic activity for hydrogen evolution reaction on Ni-based electrodeposits

The hydrogen evolution reaction (HER) was studied in 30 wt.% KOH solution at temperatures ranging between 30 and 80 °C on three type of electrodes: (i) rough pure Ni electrodeposits, obtained by applying a large current density; (ii) smooth NiCo electrodeposits; (iii) smooth commercial Ni electrodes. By using steady-state polarization curves and electrochemical impedance spectroscopy (EIS) the surface roughness factor and the intrinsic activities of the catalytic layers were determined. These techniques also permitted us to determine the mechanism and kinetics of the HER on the investigated catalysts. Different AC models were tested and the appropriate one was selected. The overall experimental data indicated that the rough/porous Ni electrode yields the highest electrocatalytic activity in the HER. Nevertheless, when the effect of the surface roughness was taken into consideration, it was demonstrated that alloying Ni with Co results in an increased electrocatalytic activity in the HER when comparing to pure Ni. This is due to an improved intrinsic activity of the material, which was explained on the basis of the synergism among the catalytic properties of Ni (low hydrogen overpotential) and of Co (high hydrogen adsorption).Isaac Herraiz-Cardona is grateful to the Ministerio de Ciencia e Innovacion (Spain) for a postgraduate grant (Ref. AP2007-03737). This work was supported by Generalitat Valenciana (Project PROMETEO/2010/023)Herraiz Cardona, I.; Ortega Navarro, EM.; Garcia-Anton, J.; Pérez-Herranz, V. (2011). Assessment of the roughness factor effect and the intrinsic catalytic activity for hydrogen evolution reaction on Ni-based electrodeposits. International Journal of Hydrogen Energy. 36(16):9428-9438. https://doi.org/10.1016/j.ijhydene.2011.05.047S94289438361

Modification of Hydrophilic and Hydrophobic Surfaces Using an Ionic-Complementary Peptide

Ionic-complementary peptides are novel nano-biomaterials with a variety of biomedical applications including potential biosurface engineering. This study presents evidence that a model ionic-complementary peptide EAK16-II is capable of assembling/coating on hydrophilic mica as well as hydrophobic highly ordered pyrolytic graphite (HOPG) surfaces with different nano-patterns. EAK16-II forms randomly oriented nanofibers or nanofiber networks on mica, while ordered nanofibers parallel or oriented 60° or 120° to each other on HOPG, reflecting the crystallographic symmetry of graphite (0001). The density of coated nanofibers on both surfaces can be controlled by adjusting the peptide concentration and the contact time of the peptide solution with the surface. The coated EAK16-II nanofibers alter the wettability of the two surfaces differently: the water contact angle of bare mica surface is measured to be <10°, while it increases to 20.3±2.9° upon 2 h modification of the surface using a 29 µM EAK16-II solution. In contrast, the water contact angle decreases significantly from 71.2±11.1° to 39.4±4.3° after the HOPG surface is coated with a 29 µM peptide solution for 2 h. The stability of the EAK16-II nanofibers on both surfaces is further evaluated by immersing the surface into acidic and basic solutions and analyzing the changes in the nanofiber surface coverage. The EAK16-II nanofibers on mica remain stable in acidic solution but not in alkaline solution, while they are stable on the HOPG surface regardless of the solution pH. This work demonstrates the possibility of using self-assembling peptides for surface modification applications

Surface science of soft scorpionates

The chemisorption of the soft scorpionate Li[PhTmMe] onto silver and gold surfaces is reported. Surface enhanced Raman spectroscopy in combination with the Raman analysis of suitable structural models, namely, [Cu(κ3-S,S,S-PhTmMe)(PCy3)], [Ag(κ3-S,S,S-PhTmMe)(PCy3)], [Ag(κ2-S,S-PhTmMe)(PEt3)], and [Au(κ1-S-PhTmMe)(PCy3)], are employed to identify the manner in which this potentially tridentate ligand binds to these surfaces. On colloidal silver surface-enhanced Raman spectroscopy (SERS) spectra are consistent with PhTmMe binding in a didentate fashion to the surface, holding the aryl group in close proximity to the surface. In contrast, on gold colloid, we observe that the species prefers a monodentate coordination in which the aryl group is not in close proximity to the surface