H2O2 Solution Research Articles

Green Synthesis of Zinc Oxide Nanoparticles via Dennettia tripetala Extracts: Optimization, Characterization, and Biological Activity Evaluation

ABSTRACTThis study examined the synthesis of zinc oxide nanoparticles (ZnONPs) with ethanolic extract from leaf and fruit of Dennettia tripetala (Class: Annonaceae) and the assessment of their biological activities. Mixing of Zn (C2H3O2)2.2H2O solution and the ethanolic extracts resulted in color change, indicating the formation of ZnONPs. pH, temperature, and concentration of metal ions were varied to optimize the amount of nanoparticles formed. Ultraviolet‐visible (UV‐Vis) spectroscopy gave a surface plasmon resonance (SPR) peak at 356 nm (DTL‐ZnONPs) and 367 nm (DTF‐ZnONPs), confirming the presence of the synthesized ZnONPs. The scanning electron microscopy (SEM) shows aggregation of spherical and rod‐like shaped nanoparticles. x‐Ray diffraction (XRD) analysis is crystalline in nature with an average crystallite size of 17.17 ((DTL‐ZnONPs) and 12.90 (DTF‐ZnONPs) nm. FT‐IR analysis showed O─H, C═O, N─H, and C─C stretching and aliphatic vibrations of hydrocarbon chains of the synthesized ZnONPs. The ZnONPs gave the maximum zone of inhibition of 18.07 (DTL‐ZnONP) and 17.14 mm (DTF‐ZnONP). Antioxidant activity carried out using DPPH radical scavenging gave an IC50 value of 227.18 (DTL‐ZnONP) and 201.21 (DTF‐ZnONP) µg/mL. Moreover, the cytotoxic effect of ZnONPs is in a concentration‐dependent manner. Therefore, this work showed that ZnONPs are good potential therapeutic agents for treating microbial infection, oxidative stress, and other pertinent disease.

Highly sensitive ultra-high-performance liquid chromatography coupled with tandem mass spectrometry method for the multiplex analysis of levosimendan and its metabolites OR-1855 and OR-1896 in human plasma

Levosimendan is a positive inotrope and vasodilator used in patients with acute and chronic decompensated heart failure. It is metabolized into OR-1855 (inactive metabolite), which is further acetylated into OR-1896 (active metabolite having a prolonged half-life, hence a sustained effect). Levosimendan represents a valuable alternative to traditional inotropes with broad clinical applications in critically ill patients with cardiogenic shock, advanced heart failure and post-cardiac surgery. However, while levosimendan demonstrates dose-dependent hemodynamic effects, its pharmacokinetics has not yet been investigated in adult critically ill patients, a vulnerable population characterized by complex and unstable conditions that may significantly alter drug disposition. Therefore, pharmacokinetics studies of levosimendan and metabolites in critically ill patients require a reliable and sensitive quantification method.We developed and validated a highly sensitive method using ultra-high-performance liquid-chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) for the quantification of levosimendan, OR-1855 and OR-1896 in human plasma. To achieve the required analytical sensitivity, plasma sample preparation included protein precipitation with acetonitrile, subsequent supernatant’s evaporation to dryness under nitrogen, and reconstitution of the solid residues with a solution of H2O:MeOH 4:1, followed by a 40 µL-aliquot injection into the LC column. Chromatographic separation of the three analytes was achieved in a 6-minute run in gradient mode, using an Acquity UPLC BEH C18 1.7µm, 2.1 ×150mm column. The method was extensively validated according to international bioanalytical assay guidelines, on a clinically relevant concentration range of 0.1 to 100ng/mL, for each analyte. Considering these very low concentrations, the assay showed excellent performances in terms of trueness (94.3-105.3%), repeatability (1.9-7.2%) and intermediate fidelity (2.3-9.7%).Of note, during our ex vivo studies on whole blood samples stability, acetylation of the metabolite OR-1855 into the active OR-1896 metabolite was observed in the presence of red blood cells.The UHPLC method is being applied for a prospective observational pharmacokinetics study of levosimendan in patients undergoing extracorporeal membrane oxygenation support. The benefit of levosimendan therapeutic drug monitoring in intensive care patients remains to be assessed.

Constructing O doped g-C3N4 nanosheets as photocatalysts for photocatalytic water splitting derived hydrogen isotopic water separation

The disposal of tritium-containing wastewater has been an enormous challenge because of its severe hazards to ecological environment. Due to the nearly identical physicochemical properties of hydrogen isotopes, the present disposal methods usually deliver low separation efficiency and high energy-intensive. Herein, photocatalytic water splitting has been firstly carried out to separate hydrogen isotopic water through the hydrogen evolution processes. The O doped graphitic carbon nitride (OGCN) as photocatalyst delivers a competitive separation factor of 4.69 with a gas evolution rate of 6.511 mmol g−1 h−1. The OGCN samples show lager surface area and abundant O dopants after the thermal oxidative etching, thus boosting the diffusion of photogenerated charge carries and delaying the recombination of photogenerated hole-electrons. The separation of hydrogen isotopes is mainly attributed to the kinetic isotope effect and the difference of bond energy between H2O and D2O. The electrochemical impedance spectra imply a lower electrical resistance of H2O than that of D2O, leading to a faster migration rate of charge carriers in H2O solution.

In-situ formation of boehmite and ammonium aluminum carbonate hydroxide for facile synthesis of γ-Al2O3 as industrial catalyst support used for hydrodesulfurization

Alumina-supported CoMo catalysts have been widely used for hydrodesulfurization of various kinds of feeds. In the current research, γ-Al2O3 was synthesized through the simultaneous formation of boehmite and ammonium aluminum carbonate hydroxide (AACH) precursors under controlled pH and temperature conditions. After optimization of the textural properties, γ-Al2O3 was utilized as catalyst support for the immobilization of catalytically active species and obtaining CoMo/γ-Al2O3-n (concentration of Al(NO3)3.9H2O solutions (n) = 30, 40, 50, 60, 70, 80, 90, and 100 g/L) catalysts via wet impregnation technique. Moreover, this preparation method was applied for the successful large-scale synthesis of CoMo/γ-Al2O3-n. The catalyst was characterized by FT-IR, powder X-ray diffraction (XRD), thermogravimetric analysis, inductively-coupled plasma (ICP), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and Brunauer–Emmett–Teller (BET). The conversion of thiophene over CoMo/γ-Al2O3 was studied to assess the catalytic performance. The catalytic activity and stability of our reported catalyst were comparable with that of KATALCOJM 41-6 T commercial catalyst. Highlights Mixture of boehmite and AACH precursors was synthesized by co-precipitation method The precursors were thermally decomposed to extruded γ-Al2O3 as catalyst support The properties of γ-Al2O3 were tuned by various concentrations of Al solution CoMo/γ-Al2O3 was prepared by the impregnation of γ-Al2O3 in the Co and Mo solutions CoMo/γ-Al2O3 catalyst was sulfided and used for hydrodesulfurization of thiophene

Enhancing intergranular corrosion resistance of 7055 Al alloy by ultrasonic shot peening

High strength 7000 series Al alloys are quite sensitive to intergranular corrosion (IGC) and generally a trade-off between IGC resistance and hardness exists in such Al alloys. Here, by using ultrasonic shot peening (USSP) we fabricate a gradient AA7055 whose IGC is significantly enhanced in both 57 g/L NaCl + 10 mL/L H2O2 solution and 3.5 wt% NaCl solution, whereas the surface hardness increases by 10 %. TEM microstructure characterization and nanoscale investigation of corrosion indicate that the improvement in IGC resistance can be attributed to the disappearance of grain boundary precipitates and precipitate free zones. Surface hardening mechanism is also revealed.

Membrane-free Electrolysis Production of Hydrogen Peroxide on Low-cost Metal-free Electrocatalysts for Dye Degradation.

The efficient production of hydrogen peroxide (H2O2) solution was achieved by combining cathodic two-electron oxygen reduction (2e- ORR) and anodic two-electron water oxidation (2e- WOR) in two half-reaction cells. h-BN loaded on carbon fibers (h-BN@C) is prepared and employed as an anode material to catalyze 2e- WOR, while sulfonated commercial BP-2000 carbons (BP-2000-SO3H) were prepared as the cathode materials for 2e- ORR. In a 2 M KHCO3 solution, an overall Faradaic efficiency of 97 % and a total H2O2 production rate of 1872 mmol g-1 h-1 over metal-free electrodes were accomplished in a membrane-free flow cell. The dilute H2O2 solution could be directly used to degrade cationic Rhodamine B or methyl blue and anionic methylene orange dyes in water. This work proved low-cost production of dilute H2O2 solution in simple membrane-free flow cells with single electrolyte and on-site utilization for efficient dye degradation.

Micellization and interfacial behavior of sodium fatty alcohol polyoxyethylene ether carboxylate surfactants in low-concentration aqueous hydrogen peroxide

The micellar properties of sodium fatty alcohol polyoxyethylene ether carboxylate surfactants in H2O2-free and H2O2-containing solutions, as well as their adsorption behavior at the gas–liquid interface, were investigated. The surface tension in water and a 6 wt% aqueous H2O2 solution was measured as a function of the logarithm of surfactant concentration, using glass plates rather than platinum plates, at temperatures of 283 K, 293 K, 303 K, 313 K, and 323 K. The data were used to calculate the critical micelle concentration (CMC), the surface tension at the CMC (γCMC), the maximum surface excess concentration (Γmax), and the minimum area occupied (Amin). The effects of the polyoxyethylene chain length, temperature, and H2O2 on the physical properties of surfactants were analyzed. The results indicated that the CMC values in water initially decreased with increasing polyoxyethylene chain length before rising due to competing effects of enhanced hydrophilicity and reduced electrostatic repulsion. Notably, the CMC decreased in the presence of H2O2, and the magnitude of the decrease was correlated with the hydrophilicity of the surfactant. Temperature variations further influenced CMC trends in different media (water and H2O2 solutions). Additionally, the presence of H2O2 altered the interfacial properties, leading to an increase in both γCMC and Amin.

Nature‐Inspired N, O Co‐Coordinated Manganese Single‐Atom Catalyst for Efficient Hydrogen Peroxide Electrosynthesis

AbstractThe two‐electron oxygen reduction reaction (2e− ORR) is a pivotal pathway for the distributed production of hydrogen peroxide (H2O2). In nature, enzymes containing manganese (Mn) centers can convert reactive oxygen species into H2O2. However, Mn‐based heterogeneous catalysts for 2e− ORR are scarcely reported. Herein, we developed a nature‐inspired single‐atom electrocatalyst comprising N, O co‐coordinated Mn sites, utilizing carbon dots as the modulation platform (Mn CD/C). As‐synthesized Mn CD/C exhibited exceptional 2e− ORR activity with an onset potential of 0.786 V and a maximum H2O2 selectivity of 95.8 %. Impressively, Mn CD/C continuously produced 0.1 M H2O2 solution at 200 mA/cm2 for 50 h in the flow cell, with negligible loss in activity and H2O2 faradaic efficiency, demonstrating practical application potential. The enhanced activity was attributed to the incorporation of Mn atomic sites into the carbon dots. Theoretical calculations revealed that the N, O co‐coordinated structure, combined with abundant oxygen‐containing functional groups on the carbon dots, optimized the binding strength of intermediate *OOH at the Mn sites to the apex of the catalytic activity volcano. This work illustrates that carbon dots can serve as a versatile platform for modulating the microenvironment of single‐atom catalysts and for the rational design of nature‐inspired catalysts.

Nature-Inspired N, O Co-Coordinated Manganese Single-Atom Catalyst for Efficient Hydrogen Peroxide Electrosynthesis.

The two-electron oxygen reduction reaction (2e- ORR) is a pivotal pathway for the distributed production of hydrogen peroxide (H2O2). In nature, enzymes containing manganese (Mn) centers can convert reactive oxygen species into H2O2. However, Mn-based heterogeneous catalysts for 2e- ORR are scarcely reported. Herein, we developed a nature-inspired single-atom electrocatalyst comprising N, O co-coordinated Mn sites, utilizing carbon dots as the modulation platform (Mn CD/C). As-synthesized Mn CD/C exhibited exceptional 2e- ORR activity with an onset potential of 0.786 V and a maximum H2O2 selectivity of 95.8 %. Impressively, Mn CD/C continuously produced 0.1 M H2O2 solution at 200 mA/cm2 for 50 h in the flow cell, with negligible loss in activity and H2O2 faradaic efficiency, demonstrating practical application potential. The enhanced activity was attributed to the incorporation of Mn atomic sites into the carbon dots. Theoretical calculations revealed that the N, O co-coordinated structure, combined with abundant oxygen-containing functional groups on the carbon dots, optimized the binding strength of intermediate *OOH at the Mn sites to the apex of the catalytic activity volcano. This work illustrates that carbon dots can serve as a versatile platform for modulating the microenvironment of single-atom catalysts and for the rational design of nature-inspired catalysts.

Continuous Electrosynthesis of Pure H2O2 Solution with Medical-Grade Concentration by a Conductive Ni-Phthalocyanine-Based Covalent Organic Framework.

Electrosynthesis of H2O2 provides an environmentally friendly alternative to the traditional anthraquinone method employed in industry, but suffers from impurities and restricted yield rate and concentration of H2O2. Herein, we demonstrated a Ni-phthalocyanine-based covalent-organic framework (COF, denoted as BBL-PcNi) with a higher inherent conductivity of 1.14 × 10-5 S m-1, which exhibited an ultrahigh current density of 530 mA cm-2 with a Faradaic efficiency (H2O2) of ∼100% at a low cell voltage of 3.5 V. Notably, this high level of performance is maintained over a continuous operation of 200 h without noticeable degradation. When integrated into a scale-up membrane electrode assembly electrolyzer and operated at ∼3300 mA at a very low cell voltage of 2 V, BBL-PcNi continuously yielded a pure H2O2 solution with medical-grade concentration (3.5 wt %), which is at least 3.5 times higher than previously reported catalysts and 1.5 times the output of the traditional anthraquinone process. A mechanistic study revealed that enhancing the π-conjugation to reduce the band gap of the molecular catalytic sites integrated into a COF is more effective to enhance its inherent electron transport ability, thereby significantly improving the electrocatalytic performance for H2O2 generation.

Graphene oxide modified screen printed electrodes based sensor for rapid detection of E. coli in potable water

A sensitive and rapid electrochemical sensor has been developed to detect Escherichia coli (E. coli) bacteria that is crucial for ensuring safe drinking water. E. coli significantly contributes to waterborne contamination, driven by overexploitation and insufficient cleanliness around water bodies. This work incorporates synthesis and characterization of graphene oxide (GO), sensor preparation, and sensor testing in the presence of varying E. coli dilutions via H2O2 decomposition. GO is used as a sensing layer and drop casted on the working electrode of screen printed electrode (SPE). The sensor is exposed to different bacterial solutions using varied bacterial concentrations and fixed percent solution of H2O2. The interface of GO and bacterial solution results in a change in potential. The cross-sensitivity tests have also been performed in the presence of chemical compounds found in wastewater samples, Pseudomonas aeruginosa and Citrobacter youngae. The sensor demonstrates a detection limit of 2.8 CFU/mL, with a sensitivity of 5.1 mV-mL/CFU, fast response time and excellent repeatability when tested with E. coli. Its performance has also been assessed by comparing the sensing results for regular tap water, reverse osmosis (RO) water, and deionized water samples. This work paves the way for developing a chip-based system to detect E. coli in water.

Reaction kinetics of molybdenum dissolution by hydrogen peroxide in acidic and alkaline solutions using tartaric acid and sodium hydroxide: A semi‐empirical model with rotating disc method

AbstractMolybdenum is an amphoteric metal that dissolves in both acidic and alkaline solutions. This fundamental study explores a sustainable process for the dissolution of molybdenum, focusing on the reaction kinetics in H2O2, H2O2‐NaOH, and H2O2‐C4H6O6 solutions. A rotating disc method was applied with the Levich's equation. Semi‐empirical models with activation energy were developed for the H2O2‐NaOH and H2O2‐C4H6O6 solutions. The study examined the effects of rotating speed, disc surface area, temperature, H2O2, NaOH, and C4H6O6 concentrations, along with rotating speed, disc surface area, and temperature. Hydrogen peroxide significantly impacted molybdenum dissolution rates across all three solutions. The reaction order of hydrogen peroxide concentration in the H2O2 solution was greater than that of the H2O2‐NaOH and H2O2‐C4H6O6 solutions. The complex of molybdenum peroxo was formed in H2O2 and H2O2‐NaOH solutions but decomposed at a temperature ≥50°C. The activation energies were determined to be 49.90, 43.60, and 41.10 kJ/mol for the H2O2, H2O2‐NaOH, and H2O2‐C4H6O6 solutions.

Development of nano-porous Au thin film at room temperature via ion irradiation in a-Ge/Au bilayer system followed by chemical etching of Ge

The development of nano-porous gold (NPG) via room temperature ion irradiation has been presented in detail. The bilayer thin films of a-Ge/c-Au have been irradiated by 100 MeV Ni ions with the fluence of 5 × 1013 ions cm−2 at room temperature. NPG is obtained by selectively etching Ge off from the Au matrix by dipping the Ge/Au thin film into 10 % H2O2 solution. Diffusion of Ge and Au across the interface under irradiation was confirmed by TRIM simulation and RBS spectra. The SEM image and EDX spectra confirms the formation of NPG with high purity. In addition, the statistical and fractal analysis of AFM image also confirms the formation of NPG. NPG system has been observed to show very good optical properties (low reflectance and high transmittance). The high quality NPG prepared by this method can be useful in the fields like optical sensors, transparent conductive electrodes, anti-reflective coatings, and photo-detector technology.

A Lab Prototype for Rapid Electrochemical Detection of Escherichia coli in Water Using Modified Screen-Printed Electrodes.

Recognizing the need for a hand-held device capable of quantitatively measuring the concentration of bacteria in water, this paper describes a label-free method for rapid detection of Escherichia coli (E. coli) in water via H2O2 decomposition using screen-printed electrodes (SPE) modified with nanostructured metal oxide layers. The study encompasses sensor preparation, bacteria culture, synthesis and characterization of nanostructures, and development of a readout circuitry for lab prototyping. During sensing measurements, the bacteria are first made to interact with H2O2 and subsequently, the H2O2 solution is exposed on the sensing surface. The electrochemical sensors are fabricated by modifying the working electrode of SPE with nanostructured metal oxide layers of MnO2 and TiO2 as these play a crucial role in the detection of E. coli in water. The sensing experiments of MnO2-modified SPE show a significant response to bacteria with a sensitivity of 0.82 mV.mL/log CFU and a limit of detection (LOD) of 1.8 CFU/mL, while the TiO2-modified SPE exhibits a linear response over a wide range of bacterial concentrations with a sensitivity of 1.12 mV·mL/log CFU and a limit of detection of 2.23 CFU/mL. Both sensors demonstrate a rapid response, stability, repeatability, and a recovery time of 70 ms. Additionally, selectivity with respect to other bacteria, wastewater components such as glucose, ammonium sulfate, and sodium carbonate, and testing with RO, DI, and tap water samples are conducted to evaluate the sensors' performance. A detailed sensing mechanism has been developed to comprehend the results, including chemical and biological reactions, metal oxide interfaces, morphology, and other surface studies of the sensing surface. A prototype comprising a sensor chip, an Arduino board, and other necessary circuit components is tested with various bacterial solutions. This enables its use for on-field rapid detection of bacteria in water using smaller volumes and a portable system.

Passivation of metal sulfides by a marine bacterium for acid mine drainage control

Acid mine drainage originates from metal sulfides oxidation, which results in acidic metal-rich leachate. In this study, a novel and environmentally friendly approach was demonstrated to passivate pyrite and lead-zinc tailings, respectively. The key to this approach is to develop biofilms of the marine bacterium Qipengyuania flava S1. Biofilms can induce biomineralization, thereby isolating metal sulfides from air and water. The stability and biological toxicity of the bio-passivation layers were evaluated by leaching bio-passivated pyrite or tailings in initially acidic H2O2 solutions with shaking for 180 days and then cultivating Brassica chinensis and Allium cepa with the leachates. Our results showed that after passivation, the amount of iron released by pyrite decreased by at least 99.2 ± 0.2 (in wt%). For lead-zinc tailings after passivation, the released metal ions (Fe+Al+Pb+Zn) decreased by at least 52.0 ± 3.2 (in wt%). The bio-passivation layers also maintained the pH of the leachate in the range of 7.5–8.0. Before bio-passivation, compared with mineral water, the pyrite leachate significantly inhibited the growth of the two plants, and the tailings leachate significantly inhibited the growth of A. cepa, whereas the bio-passivated pyrite or tailings leachate did not show any inhibitory effect.

Effect of Carbon Nanotubes Functionalization on the Chemical Composition and Electrochemical Characteristics of Composites with Layered Potassium Manganese Oxide

The influence of pretreatment of multiwalled carbon nanotubes (MWCNTs) in oxidizers (solutions of H2O2 and HNO3) on the structure and electrochemical properties of composites with layered potassium-manganese oxide (KxMnO2) was studied. Composites were obtained by soaking carbon nanotubes in an aqueous solution of KMnO4 at 60 °C. The electrochemical performance of the composites was evaluated by cyclic voltammetry and galvanostatic charge‒discharge methods. It has been established that stronger oxidation of the MWCNTs surface at the functionalization stage leads to a noticeable increase in the reaction rate as well as the optimal potassium content in the KxMnO2 composition, which provides higher capacitive characteristics of the composite (a maximum specific capacitance of 150 F g−1 and a rate capability of 43% with increasing density current from 0.1 to 2.0 A g−1). The resulting composites are promising active components for increasing the capacitive characteristics of conductive carbon black (CB). Compared with an electrode based only on CB, electrodes based on a combination of the composite and CB at a mass ratio of 1:1 showed specific capacitance values approximately 1.5 to 3 times greater, as well as a twofold increase in rate capability (from 35 to 70%) in the range of discharge current density 0.1 to 2.0 A g−1.

Preservation Potentials of Siderite in Low‐Temperature Brines Relevant to Mars

AbstractThe scarce carbonate record on the Martian surface is one of the fundamental unsolved issues for paleoclimate and environmental evolution. Whether carbonates first formed and then dissolved due to a transition in global environments or whether Mg–Fe carbonates never extensively formed due to geochemical kinetics thresholds remains unknown. In this study, we experimentally examined the preservation potential of siderite in Mars‐relevant fluids, including ultrapure water, H2O2, NaClO4, NaClO3, NaCl, Na2SO4, NaHCO3, and Na2SiO3 solutions, at 277 K. The effects of the water/rock ratio at WR10 and WR100 on dissolution rates were also investigated. We found that siderite dissolution and subsequent oxidation and hydrolysis of leached Fe did not substantially acidify the solutions. The siderite dissolved relatively rapidly in the chloride and chlorate solutions and slowly in the silica or bicarbonate solutions. In a circum‐neutral to slightly alkaline aqueous environment with oxidative species, the mobility of leached Fe was limited, leading to the formation of goethite or lepidocrocite, which clustered on the siderite surface. The longest lifetime of 1‐mm siderite grains was found in the Na2SiO3 solution at WR100, which was estimated to range from 198 ka to 198 Ma. Water‐limited, silica‐rich, and oxidative aqueous environments benefit siderite preservation on the Martian surface. Our results support that the lack of voluminous siderite on Mars may be primarily due to the inhibition of its formation rather than alteration and dissolution after its presence, consistent with the recent detection of Mg–Fe carbonate at Gale Crater and Jezero Crater.

Overcoming a Conceptual Limitation of Industrial ε-Caprolactone Production via Chemoenzymatic Synthesis in Organic Medium.

The multi-10.000 tons scale manufactured chemical ε-caprolactone attracts high industrial interest due to its favorable biodegradability properties. However, besides being of petrochemical origin yet, its production has a conceptual limitation that is the difficult extraction of this highly water-soluble monomer from the water phase resulting from the aqueous solution of H2O2 applied as reagent. In this contribution, we report a chemoenzymatic cascade starting from bio-based phenol, which makes use of O2 instead of H2O2 and runs in pure organic medium, thus requiring only simply decantation and distillation as work-up. In a first step, phenol is hydrogenated quantitatively to cyclohexanol under solvent-free conditions with a Ru-catalyst. After simple removal of the heterogenous catalyst, cyclohexanol is converted to ε-caprolactone in a biocatalytic double oxidation with very high yields just requiring O2 as reagent. This biocatalytic process proceeds in pure organic medium, thus avoiding tedious extraction to isolate the highly water-soluble ε-caprolactone and enabling a substantially simplified work-up by only centrifugal separation of lyophilized whole cells and solvent removal. This oxidation is accomplished using a tailor-made recombinant whole-cell catalyst containing an alcohol dehydrogenase and a cyclohexanone monooxygenase mutant.

Optimizing surface properties in pure titanium for dental implants: a crystallographic analysis of sandblasting and acid-etching techniques

Surface roughness is a critical factor affecting the performance of dental implants. One approach to influence this is through sandblasted, large grit, acid-etched (SLA) modification on pure titanium implant surfaces. In this study, SLA was performed on grade IV pure titanium. Sandblasting was conducted at distances of 2, 4, and 6 cm. Subsequently, the samples were etched with a mixed acid solution of HCl, H2SO4, and H2O for 0, 30, and 60 min. Surface roughness and X-ray diffraction (XRD) characterizations were conducted on the samples. The results revealed that surface roughness increased but was not too significant as the sandblasting distance decreased. Longer etching durations for sandblasted with acid-etched samples led to reduced surface roughness (Sa and Sz). It was found that a 60 min-etched sample resulted in optimal Sa, Sz, and Ssk values, i.e., 1.19 μm, 13.76 μm, and −0.60, respectively. The XRD texture was significantly influenced by sandblasting, with compressive residual stress increasing as the sandblasting distance decreased. Normal stress causes hill formations at shorter sandblasting distances. For etched samples, the residual stress decreased with longer etching durations. Normal stress-decreasing trend aligns with the initial reduction in hill and valley within the samples and subsequent hill enhancement at extended etching duration.

Spin Manipulation of Heterogeneous Molecular Electrocatalysts by an Integrated Magnetic Field for Efficient Oxygen Redox Reactions.

Understanding the spin-dependent activity of nitrogen-coordinated single metal atom (M-N-C) electrocatalysts for oxygen reduction and evolution reactions (ORR and OER) remains challenging due to the lack of structure-defined catalysts and effective spin manipulation tools. Herein, both challenges using a magnetic field integrated heterogeneous molecular electrocatalyst prepared by anchoring cobalt phthalocyanine (CoPc) deposited carbon black on polymer-protected magnet nanoparticles, are addressed. The built-in magnetic field can shift the Co center from low- to high-spin (HS) state without atomic structure modification, affording one-order higher turnover frequency, a 50% increased H2O2 selectivity for ORR, and a ≈4000% magnetocurrent enhancement for OER. This catalyst can significantly minimize magnet usage, enabling safe and continuous production of a pure H2O2 solution for 100 h from a 100 cm2 electrolyzer. The new strategy demonstrated here also applies to other metal phthalocyanine-based catalysts, offering a universal platform for studying spin-related electrochemical processes.