Degree Of Oxidation Research Articles

Characterization of HIPEs stabilized by soy protein isolate with excellent rheological properties for 3D printing: Bridging the correlation among structure, function and application

Currently, the correlation between how protein structural changes affected the function of high internal phase emulsions (HIPEs) and the regulation of 3D printing performance was still unclear. Herein, this study was aimed to research the relationship between interface properties and stability of soy protein isolate (SPI) at different degrees of oxidation and prepare HIPEs with desirable rheological properties and a solid-like structure to use for 3D printing. The findings of this study suggested that moderate oxidation led to the disruption of the protein's main chain skeleton, resulting in enhancing protein flexibility and surface hydrophobicity. The HIPEs stabilized by this condition owned higher apparent viscosity, over 70% of thixotropic recovery rate, sufficient yield stress (160.8 Pa) and higher G′ and G″. This HIPEs with excellent properties could be the food-grade 3D printing inks to produce samples with high resolution. In addition, this HIPEs exhibited a slow-release effect on free fatty acids (FFA) in the gastrointestinal digestion. Finally, the findings of the correlation analysis indicated that the flexibility and surface hydrophobicity of SPI was a key factor to affect the quality of HIPEs and 3D printing. In conclusion, moderate oxidation could change the structure and interfacial characteristics of SPI, thus endowing HIPEs stabilized by modified SPI with better properties and expanding the field of SPI in the food industry. These findings not only were of great significance for guiding protein production and providing new protein-based 3D printable materials, but also this provided new possibilities for preparing fat substitutes with good appearance.

Enhanced fretting fatigue strength of TC11 titanium alloy using laser-assisted ultrasonic surface rolling process

In this paper, ultrasonic surface rolling (USRP) and laser heating-assisted USRP (Laser-USRP) techniques are employed to enhance the fretting fatigue strength of TC11 titanium alloy. Furthermore, the surface deformation mechanism and fretting fatigue behavior are investigated. The properties of the reinforced surfaces were observed using transmission electron microscope (TEM), microhardness test, residual stress test and fretting fatigue experiments. The results showed that laser-USRP led to a remarkable enhancement in the fretting fatigue life of TC11 titanium alloy compared to traditional USRP. This was mainly due to the fact that laser heating improved the plasticity of TC11 titanium alloy, contributed to the formation of a smoother surface and increased the degree of surface oxidation, which could improve surface lubrication. Under high temperature, more slip systems were activated and more stable dislocations were formed, which resulted in larger compressive residual stress (CRS) with higher stability. The superposition of the elevated temperature field and the kinetic energy of the ultrasonic vibration produced an annealing effect in localized regions, resulting in the formation of more stable gradient nanograins. This study demonstrated the immense potential of laser-assisted plastic deformation in improving the surface properties of titanium alloys.

Crystal structure analysis of self-catalyzed InAs nanowire grown by MOCVD

We studied the crystal structure of self-catalyzed InAs nanowires with different diameters grown on Si Substrate by metal-organic chemical vapor deposition (MOCVD) and found that oxidation degree and nanowire diameter directly affect the lattice structure of InAs nanowire. In the non-oxidized state of InAs nanowires, when the diameter is greater than 160 nm, the lattice structure is mainly cubic zinc blende (ZB) structure. When the diameter is between 121 nm and 80 nm, ZB structure and hexagonal wurtzite (WZ) structure coexist. When the diameter is less than 66 nm, the lattice structure is mainly WZ structure. In the fully oxidized state of InAs nanowires, a stable layer of In2O3 is formed on its surface, and InAsO4 will be formed inside due to infiltrated oxygen atoms. When InAs nanowires are made into nanoelectronic devices as the core material, if oxidation is not prevented, InAs material with excellent electrical conductivity will also become InAsO4.

Zero-valent iron in phosphate removal: Unraveling the role of particle size and dissolved oxygen

The effect of particle size and dissolved oxygen (DO) on zero-valent iron (ZVI) oxidation needs further study to propose strategies for improving phosphate (P) removal performance. In this study, batch and column experiments were conducted to investigate P removal by ZVI with five different particle sizes under aerobic and anaerobic conditions. The oxidation status of ZVI before and after the reaction was characterized. Under aerobic conditions, as ZVI size increased, the P removal rate initially increased and then decreased, while the difference in P removal was not obvious under anaerobic conditions. Furthermore, the P removal rate exhibited a significant positive correlation with the degree of ZVI oxidation (R2 = 0.877, p = 0.008), highlighting its pivotal role in P removal. The ZVI size and DO on ZVI oxidation primarily affect the types and quantities of iron corrosion products (FeCPs). Under aerobic conditions, the ZVI with small particle sizes (ZVIsps) (50 nm, 500 nm, and 5 μm) tended to form passivation layers composed of amorphous iron oxide (ap-FexOy) and FePO4, limiting ZVI oxidation and resulting in lower P removal rates (17.6%). Conversely, in situations with less passivation, amorphous iron hydroxides (ap-FexOHy) play a dominant role in the P removal process. The 50 μm ZVI eventually generated lepidocrocite (γ-FeOOH) under aerobic conditions, this sufficient oxidation was also the reason for its high P removal rate. Therefore, future research and applications of ZVI materials in P removal should concentrate on enhancing ZVI corrosion and regulating the formation of suitable FeCPs.

One step synthesis of FeOx magnetic nanoparticles in the microreactor with intensively swirling flows

One step method of iron oxides nanoparticles synthesis using novel type of microreactors was reported. All the data received from analysis of physical and chemical properties demonstrated that the nanoparticles obtained by means of the new method are similar to the nanopowders synthesized by wet precipitation. They are magnetite-maghemite solid solutions with unit cell parameter between 8.362 and 8.374 Å, with coherent scattering range values about 9 nm. In comparison with precipitated nanopowders they have lesser degree of agglomeration. Samples obtained in microreactor have smaller value and smaller spread in regard of the specific surface (76–86 m2/g) in comparison with precipitated ones (75–125 m2/g). All the samples from microreactor consist of spherical inhomogeneities with a diffuse surface, while sample of iron oxide nanopowder synthesized by the co-precipitation method consists of scattering cylindrical inhomogeneities with nearly smooth phase boundary. It was shown that microreactor with intensively swirling flows has demonstrated several advantages: (i) possibility to control the degree of oxidation of the product which depends on the flow rates of reagents solutions to the reactor; (ii) high productivity (up to 7 L/min for the suspension with particles, approx. 200 kg/day for the dried particles) that eases the scaling-up of the proposed synthesis method.

Influence of ozone pollution on the mixing state and formation of oxygenated organics containing single particles

The formation and aging processes of oxygenated organic molecules (OOMs) are important for understanding the formation mechanisms of secondary organic aerosols (SOAs) in the field. In this study, we investigated the mixing states of OOM particles by identifying several oxygenated species along with the distributions of secondary organic carbon (SOC) during both clean and ozone (O3)-polluted periods in July and September of 2022 in Guangzhou, China. OOM-containing particles accounted for 57 % and 49 % of the total detected single particles in July and September, respectively. Most of the OOM particles were internally mixed with sulfate and nitrate, while elemental carbon and hydrocarbon species were absent. Despite the higher SOC/OC ratio in September (81 %) than it in July (72 %), comparative investigations of the mass spectra, diurnal patterns, and distributions of OOM particles revealed the same composition and aging states of OOMs in two O3 pollution periods. As the O3 concentration increased from the clean to the polluted periods, the ratio of SOC to OC increased along with the relative abundance of secondary OOM particles among total OOM particles. In contrast, the relative abundance of OC-type OOM particles gradually decreased, indicating the conversion of hydrocarbon species into OOMs as the SOC/OC ratio increased. Both the bulk analysis of SOC from filter measurement and the mixing states of OOM particles suggested that OOM production and degree of oxidation were higher in the O3-polluted periods than in the clean periods. These results elucidate the effects of O3 pollution on the OOM formation process and offer new perspectives for the joint investigation of SOA production based on filter sampling and single-particle measurements.

Nanocarbon Dimensionality and Oxidation Degree Influence the Sorption of Atenolol: Implications for Water Treatment

Nanocarbon Dimensionality and Oxidation Degree Influence the Sorption of Atenolol: Implications for Water Treatment

MAAP code analysis for the in-vessel phase of Fukushima-Daiichi Nuclear Power Station Unit 1 and comparison of the results among Units 1 to 3

The accident progression of the in-vessel phase of Fukushima Daiichi Nuclear Power Station Unit 1 was analyzed using the MAAP code. Although there is a large uncertainty in the initial stage of accident progression behavior in Unit 1 with little measurement data, it is presumed to have similarities to that of Unit 3. As a result, in Unit 1, since there was almost no alternative water injection during the in-vessel phase, cooling of the debris transferred to the lower plenum was small. It was likely that a large molten pool of metals had formed, and that the steam supply to the high-temperature core materials was suppressed and metal oxidation was relatively small. The analysis results for Unit 1 were compared with those for Units 2 and 3, and differences between units such as the thermal conditions of the debris that relocated to the pedestal and the degree of metal oxidation were shown.

Strong associations between dissolved organic matter and microbial communities in the sediments of Qinghai-Tibetan Plateau lakes depend on salinity

In aquatic ecosystems, dissolved organic matter (DOM) plays a vital role in microbial communities and the biogeochemical cycling of elements. However, little is known about the associations between DOM and microbial communities in lake sediments. This study investigated the composition of water-extractable organic matter and microbial communities in surface sediments of lakes with different salinities on the Qinghai-Tibet Plateau. Ultrahigh-resolution mass spectrometry and high-throughput microbial sequencing techniques were employed to assess the associations between molecular diversity and microbial diversity and the effects of salinity in 19 lakes spanning a salinity range from 0.22 ‰ to 341.87 ‰. Our results show that increasing salinity of lake water led to higher molecular diversity of DOM in surface sediments. High-salinity lakes exhibited distinct DOM characteristics, such as lower aromaticity, smaller molecular weight, and higher oxidation degree, compared to freshwater lakes. The complexity of the microbial network composition of sediments first increased and then decreased with the increase of salinity. Moreover, as salinity increases, the dominant species transitioned from Gammaproteobacteria to Bacteroidia, and this transition was accompanied by a decrease in microbial diversity and an increase in molecular diversity. Microbial factors accounted for 34.68 % of the variation in the molecular composition of DOM. Overall, this study emphasizes the significant effects of salinity on both molecular and microbial diversity in lake sediments. Furthermore, our findings underscore the importance of microbes in controlling the range of organic compounds present in lakes and deepen our knowledge of the biogeochemical cycling of DOM.

Synthesis, XPS and NEXAFS spectroscopy study of Zn, Cr codoped bismuth tantalate pyrochlores

The study investigated the formation of inhomophase ceramics through Zn doping in Bi2СrTa2O9.5–Δ. It was found that all Bi2ZnxCr1–xTa2O9.5–Δ (0.3 ≤ x ≤ 0.7) investigated samples crystallized in the pyrochlore structural type (sp. Gr. Fd-3m) and contained an admixture of triclinic β-BiTaO4 (up to 24 wt %, sp. gr. P-1), with the admixture concentration proportional to the degree of zinc doping. It was shown that impurities in the samples could be eliminated by creating a defective bismuth sublattice proportional to the impurity content, resulting in single-phase Bi2–yZnxCr1–xTa2O9.5–Δ (y ≤ 0.5, 0.3 ≤ x ≤ 0.7) samples with the pyrochlore structure. The unit cell parameter of pyrochlore increased with an increase in zinc ion content in the samples from 10.4493 Å (x = 0.3) to 10.4976 Å (x = 0.7). The microstructure of ceramics was represented by individual slightly melted grains 0.5–2 μm in size, which increased in size and fuse with each other with an increase in zinc content. The near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data showed that zinc doping did not change the oxidation degree of bismuth and tantalum in pyrochlore, with the ions in charge states Bi(+3), Zn(+2) and Ta(+5). The study also observed an energy shift of the absorption band in the Ta 4f spectrum toward lower energies (ΔE = 0.55 eV) characteristic of tantalum ions with an effective charge (+5–δ) and a shift of the Bi 4f7/2 and Bi 4f5/2 bands shift to lower energies with increase in x(Zn), due to the distribution of some Zn(II) ions in the bismuth position. The oxidation degree of chromium ions in the samples was mainly (+3), with some chromium ions oxidized and having an oxidation degree close to (+6) according to NEXAFS data. The studied ceramics showed promise as dielectrics for multilayer ceramic capacitors and devices for microwave applications due to their low sintering temperature and high porosity.

Variability in molecular composition and optical absorption of atmospheric brown carbon aerosols in two contrasting urban areas of China

Atmospheric brown carbon (BrC) aerosols were investigated at two urban sites in southern (Hefei) and northern (Shijiazhuang) China during summer and winter of 2019–2020 to explore regional variability in their compositional and optical properties. Organic matter in ambient PM2.5 samples were characterized at molecular level using ultrahigh performance liquid chromatography coupled with a diode array detector and an Orbitrap mass spectrometer. Although the molecular composition of organic aerosols varied substantially over different ambient environments, they were mainly composed by CHO and CHON species in positive ionization mode while CHO and CHOS species in negative mode. The mass absorption coefficients of BrC aerosols at wavelength range 250–450 nm were relatively higher for winter samples in both cities and for Shijiazhuang samples in both seasons, partly attributed to the higher concentration levels of anthropogenic air pollutants in these environments. The absorption Ångström exponents further revealed that BrC aerosols in winter seasons and in Shijiazhuang had a greater capacity of absorption at shorter wavelengths. A total of 26 BrC species with strong absorption were unambiguously identified from different environments, which mainly consisted of CHO, CHON, and CHN species and had higher degrees of unsaturation and lower degrees of oxidation. The presence and abundance of these BrC species varied dynamically across the seasons and cities, with a greater number of species presented in the winter of Shijiazhuang. The BrC species together contributed 12–26 % in the total absorbance of light-absorbing organic components at 250–450 nm. This study highlights the regional differences in BrC properties influenced by the sources and atmospheric processes, which should be taken into account to assess their climate impacts.

High temperature oxidation behavior of CoCrFeNiMo0.2 high-entropy alloy coatings produced by laser cladding

The oxidation behavior of CoCrFeNiMo0.2 high-entropy alloy laser cladding coatings at 700°C and 900°C was investigated. The oxidation kinetics of the alloys at all temperatures followed a parabolic behavior, with the oxidation rates increasing significantly with increasing temperature. The alloy exhibits excellent oxidation resistance at 700 °C. Compared with the original alloy structure, the segregation of Mo element in the alloy is more serious after high-temperature treatment. Compared with 700 °C, the oxidation degree of the alloy is more intense at 900 °C. The reaction between iron and chromium oxides forms a chromite layer, and the rapid diffusion of iron ions in the layer forms an outer layer of iron oxides. As the oxidation proceeds, the oxide film is separated from the metal, and the chromium oxide layer grows between the spinel layer and the metal. The thermodynamics of the reaction was calculated, the oxidation mechanism of the alloy was explored, and a high-temperature model of the alloy was developed. This study expands the potential applications of high entropy alloys in surface engineering.

Synthesis of graphene oxide: Effect of sonication during oxidation

The oxidation of graphite to graphene oxide (GO) is a widely used approach to exfoliate graphite. Nevertheless, achieving precise control over the degree of oxidation and the resulting properties of GO has considerable challenges. In this study, we demonstrate that using sonication during the oxidation of graphite by Hummers' method alters the chemistry and properties of the GO. Contrary to our expectations, we found that sonication slows the oxidation of graphite by impeding the intercalation of sulfuric acid. This results in fewer oxygen-containing functional groups on the GO and minimizes functionalization of the basal plane of the graphene oxide sheets, leading to superior electrochemical and mechanical properties of GO-based composites compared to GO synthesized without sonication. In this study, we use X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared spectroscopy (FTIR), cyclic voltammetry, and compression testing to quantify the effects of sonication during oxidation and propose the mechanism leading to those effects.

High performance self-assembled sulfidized nanoscale zero-valent iron for the immobilization of cadmium in contaminated sediments: Optimization, microbial response, and mechanisms

Sulfidized nanoscale zero-valent iron (S-nZVI) showed excellent removal capacity for cadmium (Cd) in aqueous phase. However, the remediation effects of S-nZVI on Cd-contaminated sediment and its interactions with microorganisms in relation to Cd fate remain unclear. The complexity of the external environment posed a challenge for Cd remediation. This study synthesized S-nZVI with different S and Fe precursors to investigate the effect of precursors and applied the optimal material to immobilize Cd in sediments. Characterization analysis revealed that the precursor affected the morphology, Fe0 crystallinity, and the degree of oxidation of the material. Incubation experiments demonstrated that the immobilization efficiency of Cd using S-nZVIFe3++S2- (S/Fe = 0.14) reached the peak value of 99.54%. 1% and 5% dosages of S-nZVI significantly reduced Cd concentration in the overlying water, DTPA-extractable Cd content, and exchangeable (EX) Cd speciation (P < 0.05). Cd leaching in sediment and total iron in the overlying water remained at low levels during 90 d of incubation. Notably, each treatment maintained a high Cd immobilization efficiency under different pH, water/sediment ratio, organic acid, and coexisting ion conditions. Sediment physicochemical properties, functional bacteria, and a range of adsorption, complexation and precipitation of CdS effects dominated Cd immobilization.

The NMR relaxivity of gadolinium (III) solutions as the function of oxidation level and flake size of graphene oxide

Chelating by graphene oxide (GO) results in dramatic shortening of the proton relaxation times of Gd3+ aqueous solutions. However, the factors, leading to the increase of relaxivity values, and the mechanisms behind the observed phenomena remain elusive. In this work, we investigated how the relaxation times of the GO/Gd3+ solutions depend on the oxidation level and the flake size of GO. The values of spin-lattice (r1) and spin-spin (r2) relaxivities increase with the oxidation degree of the used GO samples. The relaxivity also increases with decreasing the particle size of GO flakes by sonication. The observed phenomena are explained by the increase in the number of the edge functional groups, generated under the influence of both parameters. The content of these groups, their formation, and chelation of Gd3+ ions is discussed in the manuscript. Viscosity of solutions does not directly affect the relaxation times. With the use of high oxidation level and small particle size GO samples we have registered the record high relaxivity values: r2 = 114.7 mM−1 s−1, and r1 = 97.0 mM−1 s−1. This opens straight routes for developing the GO/Gd3+ based MRI contrast agents.

Study on wear protection performance of HVAF WC–Cr3C2–Ni coatings deposited on crystallizer surface

A crystallizer is the most crucial component of the continuous casting and rolling process, and it is required to operate effectively at high temperatures and loads for an extended period. In this study, WC–Cr3C2–Ni cermet coatings with high strength and wear resistance were deposited on the surface of a copper alloy crystallizer using high-velocity air-fuel spraying. The microstructure of the coating and its protective effect on the substrate at different temperatures were analyzed. The coating on the copper substrate was uniform and dense, with a porosity of 0.34 % and stable phases. Wear test results at room temperature showed that copper substrate underwent oxidative peeling failure when subjected to wear, and exhibited severe abrasive and adhesive wear, while WC–Cr3C2–Ni coating had no peeling damage on the surface when subjected to wear. In addition, the friction coefficient of the substrate was reduced from 0.624 to 0.489, thus significantly improving the wear resistance of the crystallizer surface. At high temperature (300 °C), the friction coefficient of coating increased to 0.676. Although the degree of oxidation and fatigue wear of the coating increased, the surface of the coating remained intact without any failure area. WC–Cr3C2–Ni coating protected the crystallizer continuously under high-temperature loading conditions for a prolonged time, indicating enhanced service life of the crystallizer. This study provides significant findings for developing new crystallizer coatings.

Polymer Composites with Carbon Fillers Based on Coal Pitch and Petroleum Pitch Cokes: Structure, Electrical, Thermal, and Mechanical Properties.

The effect of particle size and oxidation degree of new carbon microfillers, based on coal pitch (CP) and petroleum pitch (PET) cokes, on the structure as well as thermal, mechanical, and electrical properties of the composites based on ultrahigh molecular weight polyethylene (UHMWPE) was investigated. The composites studied have a segregated structure of filler particle distribution in the UHMWPE matrix. It was found that composite with smaller CP grain fraction has the highest Young's modulus and electrical conductivity compared to the other composites studied, which can be the result of a large contribution of flake-shaped particles. Additionally, conductivity of this composite turned out to be similar to composites with well-known carbon nanofillers, such as graphene, carbon black, and CNTs. Additionally, the relationship between electrical conductivity and Young's modulus values of composites studied was revealed, which indicates that electrical conductivity is very sensitive to the structure of the filler phase in the polymer matrix. In general, it was established that the properties, especially the electrical conductivity, of the composites studied strongly depends on the size, shape, and oxidative treatment of CP and PET filler particles, and that the CP coke of appropriately small particle sizes and flake shape has significant potential as a conductive filler for polymer composites.

Influence of Synthesis Parameters on the Short-Range Structure and Electrochemical Performances of Li2MnO2F.

In the last years, disordered rocksalt structure (DRS) materials were proposed as a positive electrode for lithium-ion batteries. In particular, the fluorinated DRS materials were proposed to be more stable upon cycling than pure oxide counterparts. These materials are mainly obtained by mechanosynthesis in order to incorporate a significant number of F ions and maintain a disordered structure. Since the local structural arrangement is crucial for battery application, we aim to monitor its evolution upon the synthesis of Li2MnO2F from two sets of precursors: Mn2O3, Li2O, and LiF or LiMnO2 and LiF. The synthesis progress was thus followed, by 7Li and 19F MAS NMR coupled to XRD to probe the structure at different scales. This allowed us to identify an optimal milling time to reach the final compounds. We show that they exhibit similar morphology (by SEM), medium- and short-range orders (by XRD, 7Li and 19F NMR, EXAFS), and average Mn oxidation degree (by XANES). The electrochemical performances of the two compounds are almost similar, with high specific capacities of 319 mAh·g-1 ("from LiMnO2") and 304 mAh·g-1 ("from Mn2O3") for the first charge to 4.8 V vs Li+/Li, proving their interest as post-NMC candidates as positive electrode materials.

Polyarene Oxides with Tunable Quinone Units for Photocatalytic CO2 Reduction: A Simple Strategy toward Effective and Selective Catalysts.

The photocatalytic transformation of carbon dioxide (CO2) into valuable chemicals is a challenging process that requires effective and selective catalysts. However, most polymer-based photocatalysts with electron donor-acceptor (D-A) structures are synthesized with a fixed D-A ratio by using expensive monomers. Herein, we report a simple strategy to prepare polyarene oxides (PAOs) with quinone structural units via oxidation treatment of polyarene (PA). The resultant PAOs show tunable D-A structures and electronic band positions depending on the degree of oxidation, which can catalyze the photoreduction of CO2 with water under visible light irradiation, generating CO as the sole carbonaceous product without H2 generation. Especially, the PAO with an oxygen content of 17.6% afforded the highest CO production rate of 161.9 μmol g-1 h-1. It is verified that the redox transformation between quinone and phenolic hydroxyl in PAOs achieves CO2 photoreduction coupled with water oxidation. This study provides a facile way to access conjugated polymers with a tunable D-A structure and demonstrates that the resultant PAOs are promising photocatalysts for CO2 reduction.

Effect of oxidation degree of iron-based oxygen carriers on their mechanical strength

Iron-based oxygen carriers are currently one of the most popular choices for chemical looping processes. In order to minimize losses of oxygen carrier materials in the system, it is important to assess attrition characteristics. Furthermore, in chemical looping gasification where the oxygen transfer capacity needs to be limited, a higher reduction degree of oxygen carriers can be expected. As different oxidation degrees lead to different phase compositions, this study aimed to investigate the correlation between mechanical strength of iron-based oxygen carriers and the phase composition, which is the result of oxidation degree change. Our findings demonstrate that how the phase composition may affect the attrition rate of oxygen carriers depends largely on the type of the material itself. In this study, the presence of Fe-Ti and Fe-Si combinations contribute to a generally stable attrition rate, while Fe-Ca system exhibits a decreasing attrition rate. Furthermore, attrition rate shows a more conclusive trend compared to crushing strength. Among the investigated materials, both ilmenite ore and iron sand showed a robust, stable mechanical stability with an attrition rate of approximately 0.5–1 wt%/h, which is on par with that of sand (0.5 wt%/h). The attrition rates of LD slag and mill scale are lower, about 1–3 wt%/h.