Borate Buffer Solution Research Articles

Application of nucleophilic substitution reaction for sensitive determination of heptaminol hydrochloride in pharmaceuticals

A straightforward and sensitive spectrofluorimetric approach was established for the determination of heptaminol hydrochloride (HTM-HCl) based on the derivatization of the drug through its reaction with 5-dimethylaminonaphthalene-1-sulfonyl chloride (Dansyl chloride). The reagent underwent a nucleophilic substitution of its chlorine atom with HTM to give N-(5-dimethylaminonaphthalene-1-sulfonyl)-6-amino-2-methylheptan-2-ol. The highly luminescent derivative was extracted using methylene chloride and subjected to analysis at an excitation wavelength of 345 nm and an emission wavelength of 490 nm. The chemical reaction occurred within an aqueous environment buffered with a 0.1 M borate buffer solution adjusted to pH 10.5. Experimental findings indicate that the proposed method displays sensitivity and linearity across a concentration range from 0.03 to 2 µg mL− 1. The method achieves lower detection and quantification limits of 0.016 and 0.048 µg mL− 1, respectively. The analytical validation of this method followed the guidelines outlined by the International Council of Harmonization (ICH). This approach was applied effectively for quantifying the medication in both tablet and oral drops formulations available on the market, demonstrating excellent recovery of 98.95 ± 0.45 for tablets and 99.37 ± 0.24 for oral drops with no interference from excipients.

Linear dependence of potential drop at the passive film/solution interface on film-formation potential and pH: Combining first-principles calculations with experiments

Potential drop at the oxide film/solution interface plays a critical part in numerous electrochemical processes, especially for the passivated metal-electrolyte system, affecting the passive film breakdown and the pitting initiation. There are still some controversies over the dependence of potential drop at the passive film/solution interface (φf/s) on potential and pH of electrolyte. Herein, we develop a model presenting the linear dependence of φf/s on both potential and pH, as represented by φf/s=φf/s(V=0,pH=0)0+αV+βpH. By analyzing the surface charge (i.e., point of zero charge, pHpzc) and performing first-principles calculations, we provide the insights into the effect of potential and pH on the φf/s, and into the linear relation between φf/s with pH beyond the Nernst relation that is attributed to the role of point defects in pHpzc of passive film on iron. In addition, two methods, e.g., a combination of Mott-Schottky measurement with first-principles, contact angle titration, are suggested to determine the values of α, β and φf/s(V=0,pH=0)0, respectively. The study of passivity of iron in borate buffer solutions validates our model.

Effect of passivation potential on corrosion behaviors of laser powder bed fusion FeCrCoNi high-entropy alloy

FeCoCrNi high-entropy alloy with uniform chemical composition was obtained by laser powder bed fusion. The potentiodynamic polarization tests showed that passive current increased with selected higher passivated potential in borate buffer solution. The semiconductor characteristic measurement displayed that passive films on laser powder bed fusion sample exhibited bilayer characteristics in the corrosion environment. Higher passivation potential facilitated to induce more point defects in the passive films, which resulted into incompact surface passive films on laser powder bed fusion sample. Therefore, the resistance to corrosion for the FeCoCrNi high-entropy alloy obtained by new technology decreased with higher passivation potential.

Passivity breakdown of high-strength 7068 aluminum alloy in borate buffer solutions containing chlorides

Passivity breakdown of high-strength 7068 aluminum alloy in borate buffer solutions containing chlorides

Porous-anodic-alumina-templated Ta-Nb-alloy/oxide coatings via the magnetron-sputtering/anodizing as novel 3D nanostructured electrodes for energy-storage applications

The Ta-52 at.%Nb thin alloy films were magnetron sputter-deposited over a low-aspect-ratio nanoporous anodic-alumina template formed in 0.05 M tartaric acid solution at 250 V and modified by the pore-widening technique to enlarge the pores up to ∼500 nm. The alloy coated the pores evenly, thus forming a 3D continuous conducting nanofilm on the template. Partially anodizing the templated alloy in a borate buffer solution of pH 7.5 generated a compact amorphous mixed-oxide anodic film thickening proportionally to the applied voltage. It was revealed that the oxide on the Ta-52 at.%Nb alloy grows with a slower migration of Ta5+ ions relative to Nb5+ ions, resulting in mixing Ta2O5 and Nb2O5 in the film depth and forming a few-nm-thick Nb2O5 outmost layer. The unique migration of Ta4+, Ta3+, Nb4+, and Nb3+ ions is assumed accountable for forming corresponding suboxides in the 3D anodic film in contrast to a flat Ta-52 at.%Nb alloy film used as a reference. The 3D anodic films behave as an n-type semiconductor with a low donor density Nd = ∼2 × 1018 cm−3, appropriate for dielectric applications. An unusual two-layered structure with a sharp electrical interface revealed in the 3D oxide films anodized to 30–130 V, comprising a low-resistivity layer superimposed on the high-resistivity layer, is explained by an immobile negative space charge in the outer film part. The air-annealing at moderate temperatures releases the space charge and transforms the two layers into a high-resistivity single layer having substantially improved dielectric properties and thermostable (up to 250 °C) capacitance of 1.2 μF cm−2 achieved for the film anodized to practical 50 V. The 3D films having up to 4.5 times enlarged effective surface area can be utilized as novel metal/oxide nanostructured electrodes for electrolytic microcapacitors suitable for classical electronic circuits and energy-storage applications.

Buffer-free ozone-ferrate(VI) systems for enhanced oxidation of electron-deficient contaminants: Synergistic enhancement effects, systematic toxicity assessment, and practical applications

The combination of ozone (O3) and ferrate (Fe(VI)) oxidation technology demonstrates substantial potential for practical applications, though it has been underreported, resulting in gaps in comprehensive activity assessments and thorough exploration of its mechanisms. This study reveals that the previous use of a borate buffer solution obscured certain synergistic reactions between O3 and Fe(VI), causing a reduction of activity by ∼40 % when oxidizing the electron-deficient pollutant atrazine. Consequently, we reassessed the activity and mechanisms using a buffer-salt-free O3/Fe(VI) system. Our findings showed that the hydroxyl radical (·OH) served as the predominant active species, responsible for an impressive 95.9 % of the oxidation activity against electron-deficient pollutants. Additional experiments demonstrated that the rapid production of neglected and really important superoxide radicals (·O2-) could facilitate the decomposition of O3 to generate ·OH and accelerate the reduction of Fe(VI) to Fe(V), reactivating O3 to produce ·OH anew. Intriguingly, as the reaction progressed, the initially depleted Fe(VI) was partially regenerated, stabilizing at over 50 %, highlighting the significant potential of this combined system. Moreover, this combined system could achieve a high mineralization efficiency of 80.4 % in treating actual coking wastewater, complemented by extensive toxicity assessments using Escherichia coli, wheat seeds, and zebrafish embryos, showcasing its robust application potential. This study revisits and amends previous research on the O3/Fe(VI) system, providing new insights into its activity and synergistic mechanisms. Such a combined technology has potential for the treatment of difficult-to-degrade industrial wastewater.

Electrochemical investigation of electrophoretically deposited graphene-oxide coating on AZ31 alloy prepared using in-house synthesized few-layer graphene-oxide nanosheets

Magnesium and its alloys possess low density and superior specific strength making it a potential structural metal to be used in different engineering fields. However, its proneness to corrosion limits its applications. In this novel study, an eco-friendly graphene-oxide coating was prepared on AZ31 magnesium alloy via electrophoretic deposition to enhance its anti-corrosion properties. Scanning electron microscopy coupled with energy dispersive spectroscopy, atomic force microscopy, and scratch test were adopted to investigate surface morphology, roughness, chemical composition, and adherence of the coating. The corrosion behaviour of graphene-oxide coated alloy was studied using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt% NaCl and Borate Buffer solutions. The obtained results demonstrate that the coating developed on AZ31 alloy is smooth and adherent with the hardness of the as-deposited coating measuring as high as 6.0 GPa. In addition, the electrochemical corrosion behaviour studies revealed that the coating significantly increased the corrosion potential (Ecorr) of the alloy towards more noble values (−0.65 V < Ecorr < −0.35 V), with the coated alloys possessing a charge transfer resistance nearly two orders of magnitude greater than their non-coated counterparts. Consequently, the corrosion rate of the coated alloy decreased substantially, indicating that the coating exhibits exceptional corrosion resistance (0.045–0.09 mm/a in 3.5 wt% NaCl and 0.002–0.006 mm/a in Borate Buffer). These findings challenge the conventional beliefs that graphene exhibits strong cathodic behaviour towards anodic materials such as AZ31 alloy. Thus, the outcomes not only have the potential to revolutionize the advancement of graphene-oxide coatings for corrosion resistance but could also possibly expand AZ31 alloy’s applications in the aerospace and automotive sectors.

Dielectric bi-layer model for electrochemical impedance spectroscopy characterisation of oxide film

In this study, the impedance response of a passive material is investigated, attributing it to a normal time constant distribution caused by resistivity variations within the passive film. Two models, namely the Power Law Model (PLM) and the recently developed Dielectric Bi-Layer Model (DBLM), are employed to express the impedance data. The PLM considers an oxide film as a single layer with a power-law distribution of resistivity, while the DBLM incorporates two distinct layers: an inner layer with constant resistivity (ρ0) and an outer layer with resistivity following Young's theory. Application of both models to 316L stainless steel immersed in a borate buffer solution exhibit that PLM and DBLM fitting results are in good agreement with experimental data. While the models differ mainly in resistivity profiles at the vicinity of the outer interface, the results suggest that deviations in regressed parameters indicate similar ranges for resistivity profiles calculated by both models. DBLM, in particular, is highlighted as promising for interpreting impedance data of passive materials due to its reliance on physical concepts.

Sunlight-driven selective oxidation of glycerol on formate oxidase mimicking AuPt/TiO2

We report selective photocatalytic partial oxidation of glycerol on bimetallic formate oxidase mimicking AuPt/TiO2, with a unique self-accelerating reaction kinetics discovered for the first time. Systematic investigation on the glycerol oxidation in the presence of externally added formic acid and various scavengers reveals a positive correlation between photocatalytic activity and solution H2O2 level. A reaction mechanism has been put forward, where the in situ generated formic acid consumes photogenerated holes, and enables on-site H2O2 production on AuPt/TiO2, resulting in accelerated glycerol oxidation and improved C3 product selectivity. In pH 9 borate buffer solution, C3 products selectivity of 72% (60% for glyceric acid) has been achieved at 90% glycerol conversion under AM 1.5 G irradiation for 4 h, at ambient conditions. Our findings presented here may help guiding catalyst design for the photocatalytic biomass valorization in the future.

Gradient‐Tuned VO4 Vacancies in BiVO4 Photoanode for Boosting Bulk Hole Transport and Oxygen Evolution Reaction Performance

AbstractAlthough bismuth vanadate (BiVO4) photoanode has been widely used, the solar‐driven oxygen evolution reaction (OER) performance is constrained due to the substantial bulk recombination and poor mobility of charge carriers. Herein, a facile solvothermal post‐treatment approach that employs N,N‐dimethylformamide (DMF) is developed to induce a VO4 vacancy gradient from bulk to surface of BiVO4 film, which not only improves the charge diffusion but also establishes an advantageous upward band gradient to promote the bulk hole transport. Under Air Mass 1.5 Global (AM1.5G) simulated solar illumination, the optimized BiVO4 photoanode with a VO4 vacancy gradient (denoted as B(VO)1‐δ) exhibits excellent OER performance with a charge separation efficiency of 74.4% at 1.23 V versus reversible hydrogen electrode (RHE) and incident‐photon‐to‐current conversion efficiency of 30.7% at 445 nm, 1.2 and 1.4 times higher than that of the pristine BiVO4, respectively. After loading nickel‐iron hydroxyl oxide (NiFeOOH) as a cocatalyst, the photocurrent density of B(VO)1‐δ escalates to 5.92 mA cm−2 in a hole scavenger (Na2SO3) solution and 5.07 mA cm−2 in a potassium borate buffer solution at 1.23 V versus RHE, far superior to the pristine BiVO4. This work highlights that the gradient‐tuned VO4 vacancies can effectively modulate the bulk band structure and charge transfer in BiVO4 photoanode, providing a new strategy for boosting solar water splitting performance.

Proton Radiation Effect on Iron Thermal Oxides: Point Defects, Microstructure & Corrosion Electrochemistry

Iron(Fe)-based alloys, such as austenitic stainless steels, form protective surface oxide layers when exposed to oxygen, aqueous electrolyte, and water vapor, which effectively inhibit corrosion [1]. One attribute that underpins the electrochemical reactivity of surface oxide layers is the presence and properties of charged point defects (e.g. vacancies and interstitials charge compensated by electrons or holes), which govern the rate and mechanism of ionic transport when exposed to an oxidizing environment such as an aqueous electrolyte [2,3,4]. However, the effect of radiation on the relationship between point defects, oxide microstructure, and oxidation behavior is poorly understood. Structural materials used in nuclear applications are particularly susceptible to radiation damage, which can degrade the underlying surface oxides. To investigate this phenomenon, thermally oxidized pure Fe was selected as a model material system to study radiation-induced defects in iron oxide scales [3]. Iron oxides were fabricated by thermal oxidation of pure Fe metal in air at 400°C, 600oC, and 800°C for 1 hour. Each oxides layer exhibits an outer hematite (α-Fe2O3) and inner magnetite (Fe3O4)/wüstite (FeO) layers with varying thickness depending on the oxidation conditions. These oxides were then irradiated with 200 keV, 0.03 dpa protons at room temperature. The oxide microstructure and phase compositions were characterized with transmission electron microscopy (TEM) coupled with electron energy loss spectroscopy (EELS). These results were corroborated with X-Ray diffraction (XRD) and Raman spectroscopy analysis. The relative vacancy concentrations and size distributions in the oxide layers were investigated using positron annihilation spectroscopy (PAS) and positron annihilation lifetime spectroscopy (PALS) techniques. Lastly, these oxides were exposed to a 0.1 M borate buffer solution (pH 9.2) at applied potential where corrosion reactivity was governed by interfacial reactions and ionic defects to regulate the growth processes observed. The potentials were cycled over the ranges where oxides growth and reduction occurred involving Fe/Fe(II)/Fe(III) reactions at a pH which suppressed chemical reactions at the oxide/electrolyte interface and would lead to solubilization of Fe species. The subsequent oxidation, reduction, and semiconductor properties of the oxides were evaluated using AC and DC electrochemical methods, both with and without prior irradiation. Current results demonstrate that radiation damage can manifest itself in the form of vacancy clustering and possible maghemite (γ-Fe2O3) formation. These phenomena were corroborated with donor density and diffusivity values calculated using Mott-Schottky analysis and electrochemical impedance spectroscopy (EIS) analysis and equivalent circuit model (ECM) interpretation, respectively. Radiation damages to the outer rate-regulating α-Fe2O3 layer correlates with enhanced anodic current density corresponding to Fe/Fe(II)/Fe(III) reactions. However, proton radiation may also interact with the metal/oxide and oxide/oxide interfaces depending on the oxide structure and H+ beam penetration depth, leading to either degradation or improvement in the Fe-oxide corrosion responses. Nevertheless, the damage persists and can continue to impact corrosion mechanisms long after the irradiation source is removed. The multiple techniques adopted, each characterizing a material property of a different length scale (from meso-, micro-, to macroscopic) enable us to hypothesize the roles that point defects played after irradiation and during corrosion and how the radiation-induced changes in the defect characteristics influence corrosion electrochemistry. Acknowledgment Research primarily supported as part of the fundamental understanding of transport under reactor extremes (FUTURE), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Utilization of the Malvern-Panalytical Empyrean diffractometer were supported by Nanoscale Materials Characterization Facility with National Science Foundation under award CHE-2102156. The TEM sample preparation and characterization was performed at the Analytical Instrumentation Facility at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (award number ECCS-1542015). LANL is operated by Triad National Security, LLC, for the National Nuclear Security Administration of the U.S. DOE (Contract No. 89233218CNA000001).

Electro-chemo-mechanical properties of anodic oxide (passive) films formed on Cu, Ni and Fe

Abstract Electro-chemo-mechanical properties of anodic oxide (passive) films formed on metals have been reviewed focusing on the results of stress variations caused by anodic oxidation of Cu, Ni, and Fe thin film electrodes in deaerated pH 8.4 borate buffer solution at 25 °C. The surface stress varies toward compressive direction due to adsorption of OH on Cu from aqueous solution as well as adsorption of oxygen on metals from gas phase. The stresses are generated with the growth of three-dimensional anodic oxide films on metals. The magnitude and sign (tensile or compressive) of the intrinsic film stress were determined by taking the residual stress of the substrate and the dielectrostriction into consideration. The tensile or compressive intrinsic film stress depends on p-type or n-type semiconductive properties of the anodic oxide films, which is explained in terms of the void formation or oxide formation in the metal side at the metal/film interface. Furthermore, the stress variation toward compressive direction during cathodic reduction of the anodic oxide films is explained in terms of the volume expansion due to the formation of intermediate species.

Temperature effects on the passivity breakdown of copper in chloride‐containing borate buffer solution

AbstractPassivity and passivity breakdown of pure copper were studied in alkaline chloride‐containing borate buffer solution from 25°C to 80°C by electrochemical measurements and scanning electron microscopy. The corresponding E–pH diagrams were also calculated. Increased temperatures make the open circuit potential and formation potential for cuprous oxide (Cu2O) shift in a negative direction. The mean breakdown potential shifts in a positive direction and the distribution of breakdown potential has a wider width, while the minimum breakdown potential decreases slightly at higher temperature. The anodic passive film formed at 0.4 V versus Ag/AgCl for 6 h in a chloride‐free solution at T ≥ 40°C can maintain passivity after the addition of 0.1 M NaCl, but cannot maintain passivity at 25°C at the same concentration. High temperature benefits the growth of copper oxide over the formation of copper chloride species. Cu2O and CuO have excellent corrosion resistance to 0.1 M NaCl and passivity can be maintained well above the CuO/Cu2O equilibrium at pH &gt; 8.

Inhibition efficiency and mechanism of nitrilo-tris(methylenephosphonato)zinc on mild steel corrosion in neutral fluoride-containing aqueous media

Abstract Corrosion-electrochemical behaviour of steel E 235 in borate buffer solution (pH = 7.4) containing F− ions with and with no added ZnNTP as an inhibitor, where NTP = N(CH2PO3)3, was studied by the potentiodynamic polarization and depth-profiling XPS analysis of specimens polarized at different potentials applied. Depending on the potential applied, F− ion was shown to influence differently on the formation, composition and structure of passive film. At E &lt; 0.1–0.2 V/SSCE, F− ion promotes the passivation via forming sparingly soluble FeF2, and the resulting film is comprised of mainly iron(II) oxides and hydroxides, as well as sparingly soluble FeF2 and FeZnNTP. At E &gt; 0.1–0.2 V/SSCE, F− ion works for the destruction of the passive film by forming soluble compounds with Fe3+ ions, which leads to its thinning. ZnNTP inhibitor forms FeZnNTP heterometallic complex with iron ions, which is the most stable constituent of the passive film. When F− ion concentration does not exceed 1.4 mmol/L, ZnNTP inhibitor is optimal to be added in amount of 0.5–1.0 g/L, whereas concentrations of 5.6 mmol/L F− ion and higher require 5 g/L ZnNTP or even more to be added.

A rapid detection method of three foodborne pathogens based on physical and chemical Raman spectroscopy enhanced

Escherichia coli, Listeria monocytogenes, and Salmonella typhi are three pathogens commonly found in food. Label-free enhanced substrates have limitations in achieving high sensitivity in three bacteria detection. To enable low-concentration detection and differentiation of foodborne pathogens, this research presents an optimized detection strategy using Au @Ag NPs as the enhancing substrate for SERS technology. The impact of the particle size of Au @Ag NPs and the pH of the borate buffer solution on enhancing the Raman signals of these bacteria was investigated through electromagnetic and chemical enhancement mechanisms. By evaluating the intensity of bacterial Raman spectra, and employing chemometric techniques, the concentration and classification of the three bacterial species were predicted and analyzed. The research findings revealed that the optimized detection method was able to detect three pathogens at the concentration lower than 3 lg CFU/mL. Logarithmic fitting of the bacteria enabled prediction correlations above 0.98 and prediction root mean square errors below 0.17. After normalizing, efficient discrimination of low-concentration bacteria was achieved using the PLS-DA, with a classification prediction correlation greater than 0.94. The fabrication process of the proposed enhancement substrate is simple, but the stability of signal detection needs further improvement in subsequent experimental testing steps.

The effect of build orientation on tensile properties and corrosion resistance of 316L stainless steel fabricated by laser powder bed fusion

The effects of build orientation on tensile property and corrosion behavior of laser powder bed fusion 316L stainless steel were investigated. The laser powder bed fusion 316L stainless steel in normal direction exhibited lower tensile strength and elongation than one in build direction. In view of the fact that there was no obvious martensitic transformation in the two samples, high density dislocation and more low-angle grain boundaries in laser powder bed fusion 316L stainless steel in build direction both enhanced tensile yield and tensile strength. More deformed twins in the sample in build direction induced better plasticity. In addition, laser powder bed fusion 316L stainless steel in build direction exhibited better corrosion resistance than one in normal direction in borate buffer and sodium chloride solutions. This was attributed to the larger grain and more densely packed crystallographic faces in build direction for laser powder bed fusion 316L stainless steel.

Rational Design for Selective Oxygen Evolution Reaction over CoFeOxHy at High Current Density in the Presence of Chloride Ion

Seawater electrolysis is expected to play an important role in the circular economy by reducing the hydrogen production cost due to the simplified process lines[1] and by saving scarce sources of safe and fresh water.[2] Seawater impurities especially chloride ions can cause the corrosion of the catalyst and be oxidized at high potential, competing with the oxygen evolution reaction (OER). Produced chlorine and hypochlorite are toxic to humans and the environment,[3] thus selective OER is desirable. Furthermore, impurity cations, such as Ca and Mg, may form hydroxide precipitates in a highly alkaline condition which is commonly used in the commercial electrolyzer. Therefore, selective OER in non-extreme pH (pH < 10) is highly desired, which requires additional challenges on the electrocatalyst and the electrolyte. In this study, we have effectively utilized the thermodynamic potential gap between chloride oxidation reaction (COR) and OER, and engineering of non-noble metal hydroxide electrocatalysts and buffer electrolyte successfully achieved the selective OER in the presence of chloride ion at commercially relevant operation conditions in non-extreme pH within the thermodynamic window.Firstly, the stability of non-noble metal materials in 1.0 mol kg− 1 potassium borate (K-borate, pH 9.2) buffer solution with 0.5 mol kg− 1 KCl was investigated. Ni foam and Ni hydroxide, which are commonly used in water splitting at extreme pH levels, were unstable, and Co, Fe, and Ti-based materials were found to be the candidates for seawater splitting. Among various combinations of these elements, the CoFeOxHy/TF (Ti felt) electrode showed better performance than CoOxHy/TF and FeOxHy/TF electrodes. The CoFeOxHy electrode possessed a three-hold larger double layer capacitance (C dl) which is the electrochemically active surface area than its counterparts. Our kinetic study revealed that Tafel slopes and apparent activation energies of CoFeOxHy resembled the control CoOxHy and FeOxHy electrodes, indicating that the performance difference was originated from the enlarged surface area caused by mixed Co and Fe.In addition to the development of electrocatalysts, electrolyte engineering plays a key role. By employing the CoFeOxHy/TF electrode, the OER performance was investigated in varied molality and counter cation borate electrolytes at pH 9.2. The molarity of K-borate above 1.0 mol kg− 1 was found to be essential to minimize the concentration overpotential, which helps to maintain the electrode potential below the thermodynamic window of COR. The OER performance was insensitive to cation identity except for the Na cation counterpart having a low solubility product. Furthermore, Cl−-containing electrolyte had a higher conductivity than that without Cl−, which can be an advantage to decrease the ohmic resistance in two electrode configurations for future application.The influence of the potential window on the stability and selectivity was investigated by using the developed electrode and 1.0 mol kg−1 K-borate (pH 9.2) with 0.5 mol kg−1 KCl. Below the redox potential of ClO− formation at 1.72 VRHE (V vs. Reversible hydrogen electrode), current density-potential relationships were insensitive to the Cl−. At 1.72 VRHE in the presence of Cl−, the faradaic efficiency (FE) of O2 (FEO2) reached 98±1%, whereas the FE of hypochlorite (FEHC) was merely 1±1%. Above this threshold potential, under chronopotentiometry (CP) testing at 50 mA cm−2 corresponding to approximately 1.82 VRHE, FEO2 decreased to 93±2% and FEHC increased to 7±2%. Critically, the potential of 1.82 VRHE was larger than 1.78 VRHE observed without Cl−, likely due to the blockage of the OER active site by Cl− or related species. Finally, aiming for the practical application, the OER performance over CoFeOxHy was examined at 353 K. The FEO2 reached 99±2% at 500 mA cm− 2 and 1.67 VRHE (Figure 1). Our calculations on thermodynamics revealed that the redox potential of OER decreases to 1.18 VRHE while that of ClO− formation reaction is 1.71 VRHE at 353 K, leaving a potential gap of 530 mV. High selectivity toward the OER was attributed to the consequence of fine engineering of electrocatalysts and electrolytes that successfully maintained the potential below the 1.71 VRHE where the OER is thermodynamically dominant. In addition, the electrode was stable for multiple on-off accelerated stability testing for 10 h at 500 mA cm− 2 and 353 K.Reference[1] S. Dresp, F. Dionigi, M. Klingenhof, P. Strasser, ACS Energy Lett. 2019, 4, 933–942.[2] C. J. Vörösmarty, P. B. McIntyre, M. O. Gessner, D. Dudgeon, A. Prusevich, P. Green, S. Glidden, S. E. Bunn, C. A. Sullivan, C. R. Liermann, Nature 2010, 467, 555–561.[3] J. G. Vos, M. T. M. Koper, J. Electroanal. Chem. 2018, 819, 260–268. Figure 1

Large-area deposition of protective (Ti,Al)N coatings onto polycarbonate

Polycarbonate (PC) and protective (Ti,Al)N coatings exhibit extremely different material properties, specifically crystal structure, thermal stability, and elastic and plastic behavior, as well as thermal expansion coefficients. These differences present formidable challenges for the deposition process development as low-temperature synthesis routes have to be explored to avoid a thermal overload of the polymer substrate. Here, a large-area sputtering process is developed to address the challenges by systematically adjusting target peak power density and duty cycle. Adhering (Ti,Al)N coatings with a critical residual tensile stress of 2.2 ± 0.2 GPa are obtained in the pulsed direct current magnetron sputtering range, whereas depositions at higher target peak power densities, realized by high power pulsed magnetron sputtering, lead to stress-induced adhesive and/or cohesive failure. The stress-optimized (Ti,Al)N coatings deposited onto PC with a target peak power density of 0.036 kW cm−2 and a duty cycle of 5.3% were investigated by the cross-cut test, confirming adhesion. By investigating the bond formation at the PC|(Ti,Al)N interface, mostly interfacial CNx bonds and a small fraction of (C−O)−(Ti,Al) bonds are identified by x-ray photoelectron spectroscopy, indicating reactions at the hydrocarbon and the carbonate groups during deposition. Nanoindentation reveals an elastic modulus of 296 ± 18 GPa for the (Ti,Al)N coating, while a Ti–Al–O layer is formed during electrochemical impedance spectroscopy in a borate buffer solution, indicating protective passivation. This work demonstrates that the challenge posed by the extremely different material properties at the interface of soft polymer substrates and hard coatings can be addressed by the systematical variation in the pulsing parameters to reduce the residual film stress.

Applicability of fluorescamine as a fluorogenic reagent for highly sensitive fluorimetric analysis of the tyrosine kinase inhibitor (avapritinib) in pharmaceuticals and biological samples.

Avapritinib (AVP) was the first precision drug to be approved by the US Food and Drug Administration (FDA) in 2020 for patients suffering from metastatic gastrointestinal stromal tumors (GISTs) and progressive systemic mastocytosis. The analysis of AVP in pharmaceutical tablets and human plasma was then carried out using a fast, efficient, sensitive, and simple fluorimetric method using a fluorescamine reagent. The procedure is based on the interaction between fluorescamine as a fluorogenic reagent and the primary aliphatic amine moiety in AVP using borate buffer solution at pH8.8. The produced fluorescence was measured at 465 nm (Excitation at 395 nm). The calibration graph's linearity range was discovered to be 45.00-500.0ng mL-1 . Utilizing the International Council for Harmonization (ICH) and US-FDA recommendations, the research technique was validated and bioanalytically validated. The proposed approach was effectively employed for determining the stated pharmaceuticals in plasma with a high percentage of recovery ranging from 96.87 to 98.09 and pharmaceutical formulations with a percentage of recovery equal to 102.11% ± 1.05%. In addition, the study was extended to a pharmacokinetic study of AVP with 20 human volunteers as a step for AVP management in therapeutic cancer centers.

Recrystallization effect on surface passivation of Hastelloy X alloy fabricated by laser powder bed fusion

Post-heat treatment is generally adopted in the additive manufacturing field due to its alleviation of high residual stress and modification of rapid-solidified multilevel heterogeneous microstructure, and the related performance of the heat-treated counterparts calls for a systemic investigation to build a criterion of the heat treatment procedure. In this work, we focus on the heat treatment effects on the recrystallization of the Hastelloy X alloy produced by the laser powder bed fusion (LPBF) method, and the related surface passivation of the heat-treated counterparts is meticulously assessed as well. Results show that the multilevel heterostructure for LPBF Hastelloy X alloy consists of sub-micro dislocation cell substructures with Cr/Mo elemental segregation, fine columnar grains, and periodically-distributed molten pools. After heat treatment, partially and fully recrystallized structures for LPBF Hastelloy X alloys were achieved at 1100 and 1200 °C for 1 h, respectively. Furthermore, the as-built LPBF Hastelloy X alloy shows superior corrosion resistance while the heat-treated one (1100 °C) exhibits the worst in the borate buffer solution. The growth of passive film exhibited a highly linear correlation with the nucleation process controlled by diffusion, and high dislocation density and low angle grain boundary decreased the diffusion coefficient of cation vacancies, augmenting the nucleation sites of the passive film and enhancing its growth rate. Moreover, the micro-galvanic effect resulting from the partially recrystallized microstructure actively facilitated the formation of inhomogeneous porous passive films, leading to the worst corrosion resistance.