Low Degree Of Oxidation Research Articles

Contribution of plastic solid components to volatile organic compounds formation during plastics combustion

The combustion of plastic waste releases volatile organic compounds (VOCs) that are harmful to human health. However, information on the micro-mechanisms of VOC formation remains lacking. Here, the study hypothesized and verified the relationship between VOC formation and solid component degradation during plastics combustion. The VOCs released during plastics combustion exhibit characteristics such as low carbon content (nc< 10), volatility (9μgm-3 < log10C0 < 11μgm-3), and medium oxidation degree (−1.5 <OSC¯ < −0.5). The dominant VOCs ketones/aldehydes/acids (33-43%) may be attributed to the depolymerization of the polymer structure of plastics, the oxidation of C-O/C=O groups, and the secondary cleavage of gaseous oxygen-containing macromolecules. The VOCs released from the combustion of polyethylene terephthalate (PET) and poly(butyleneadipate-co-terephthalate) (PBAT) contained more aromatics than polyethylene (PE) and polypropylene (PP). And the temperature response of aromatics released from PET and PBAT lagged other VOCs compared that of PP and PE. However, compared to biomass thermal conversion, combustion of plastics releases fewer aromatics and nitrogenous compounds. Collectively, this work shows that the formation mechanisms of VOCs contributed by the solid components during plastic combustion are similar for PET and PBAT due to their similar chemical structures. The proposed mechanism in this paper will provide insight into the control of contaminants during plastic combustion.

Impact of reduced-graphene-oxide functionalization of flower-like zinc-oxide nanostructures on sensing performance of resistive ethanol gas sensor

This research presents a sensitive resistive ethanol gas sensor based on reduced graphene oxide (rGO)-functionalized Zinc oxide nanoflowers (ZnO NFs). Upon completion of synthesis, the resulting nanostructures were cast onto the photolithographed silver interdigitated electrodes positioned on an Al2O3 substrate. The graphene oxide (GO) with a low oxidation degree was synthesized using a Hummer's method. In the pursuit of optimizing sensing performance, rGO-functionalized ZnO NFs were synthesized through a one-pot hydrothermal process, utilizing different initial quantities of GO (0 mg, 2 mg, 8 mg, and 12 mg). According to the gas sensing measurements, the fabricated sensor with 8 mg initial GO showed the highest response to ethanol at 250 °C. The results show that the GO addition reduced the optimal working temperature of the pure ZnO NFs from 350 °C to 250 °C. The sensor exhibited a good selectivity, repeatability, and high long-term stability. Enhanced ethanol sensing response of the optimized gas sensor was related to the formation of p-n heterojunction between p-type rGO (formed during hydrothermal process at 200 °C) and n-type ZnO and the presence of the optimal amount of rGO on the surface of NFs. The results obtained in this investigation stress the significance of pinpointing the optimal quantity of GO for producing rGO-ZnO nanoflowers with the highest possible sensitivity to ethanol gas.

New Derivatives of Modified Starch for Food Technology.

The food industry extensively uses chemically modified starches and their hydrolysates, which is mainly due to their emulsification ability. Therefore, it becomes inevitable to develop new starch derivatives, including modified starch hydrolysates, and effective preparation methods to meet the increasing demands of producers, consumers, and technology. This study comprehensively researches the physical, chemical, and functional properties (such as the water-binding capacity, swelling power, solubility, and fat absorption capacity) of chemically modified biopolymers and their enzymatic hydrolysis products. We utilized oxidized and acetylated potato and waxy-corn starches with varying degrees of substitution by carboxyl and acetyl groups in our research. The process of enzymatic hydrolysis was performed in a recirculated membrane reactor (CRMR). Our findings indicated that the physicochemical properties of starch derivatives and their hydrolysates depended on the biological origin of the biopolymer and the type and degree of modification. However, the presence of carboxyl groups in the modified starch molecules is critical and affects the rheological properties and water-binding capacity of the starch preparations. For example, in the case of waxy-corn starch preparations with a lower content of carboxyl groups (i.e., derivatives with a low degree of oxidation), the water-binding capacity (WBC) increases when compared to native starch. The highest WBC value of 206.3% was noted for the doubly modified waxy-corn starch with an oxidation degree of 0.2% and an acetylation degree of 2.5%, while native waxy-corn starch shows a WBC of 161.4%. In contrast, it was observed that preparations with a higher content of carboxyl groups, i.e., derivatives with an oxidation degree of 2.5%, show a lower swelling power compared to native waxy starch.

Effect of the Conversion Degree on the Apparent Kinetics of Iron-Based Oxygen Carriers.

The role of the oxygen carrier is important in energy conversion processes with fluidized beds, particularly chemical looping technology. It is necessary to establish the relevant kinetics of oxygen carriers that can be applicable for various chemical looping processes. In this study, we analyzed the apparent kinetics of three iron-based oxygen carriers, namely, ilmenite, iron sand, and LD slag, during the conversion of CO, H2, and CH4 in a fluidized bed batch reactor. The effect of both the oxidation degree, presented as the mass conversion degree, and temperature was considered. The results show that the changing grain size (CGS) model is generally applicable in predicting the apparent kinetics of reactions between the investigated iron oxygen carriers and gaseous fuels even at lower oxidation degrees (3-5 wt % reduction). The activation energies of the investigated materials in the conversions of CO, H2, and CH4 obtained from the fittings of the CGS model are about 51-92, 55-251, and 72-211 kJ/mol, respectively. Both the mass conversion degree and temperature influence the reactivity of oxygen carriers in a directly proportional way, especially at temperatures higher than 925 °C. The results of this study are useful for reaction engineering purposes, such as designing a reactor, in chemical looping units, or in any other processes that use oxygen carriers as a bed material.

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.

Characteristics of corrosion products of steel bars in modified magnesium oxysulfide cement containing chloride salts

The effects of chlorides on the corrosion of steel bars within a matrix comprising modified magnesium oxysulfide (MMOS) cementitious materials was investigated. The phase composition, morphology and distribution of steel corrosion products (SCPs) were studied. There was basically no corrosion of the steel bars in the MMOS cement without chlorides. A high chloride content and a high water/cement (w/c) ratio in the MMOS matrix had adverse effects on the steel bar corrosion. The primary SCPs in the MMOS mixes were iron oxyhydroxides (FeOOH) and ferric oxide (Fe2O3), while ferrous oxide (FeO) was only observed at low w/c ratios, indicating a lower degree of oxidation. The presence of di-iron nonacarbonyl (Fe2(CO)9) at high w/c ratios suggested a higher degree of oxidation. At lower w/c ratios, rust products readily diffused. Conversely, at higher w/c ratios, these products accumulated close to the steel bars, resulting in a compact structure.

UV‐Induced Synthesis of Graphene Supported Iridium Catalyst with Multiple Active Sites for Overall Water Splitting

AbstractCatalysts that can promote the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are in demand for efficient water splitting. Here, a general and practical UV‐induced synthesis of noble metal catalysts supported on reduced electrochemical graphene oxide (M‐rEGO, M = Ir, Pt or Pd) is proposed. The use of EGO with a low degree of oxidation and the generation of the highly reducing isopropanol radical from added isopropanol and acetone are crucial for this one‐step, one‐pot synthesis. Using Ir as a model material, the vacancies of rEGO allow the interaction of undercoordinated C with Ir, forming multiple active Ir species including single atoms (SAs), dual‐atom pairs (DAs) and nanoparticles. This Ir‐rEGO catalyst exhibits overpotentials of only 42.3 and 294 mV to reach 10 mA cm−2 in 0.5 м H2SO4 for HER and 1 м KOH for OER, respectively, at an extremely low Ir loading (2.1 wt%). The water‐splitting cells featuring Ir‐rEGO catalyst outperform those using commercial Pt/C (20 wt%) and RuO2 catalysts in both acidic and alkaline electrolytes. Density functional theory calculations confirm the stabilization of SAs and DAs at the vacancies of graphene lattice as well as the high activity of DAs in both HER and OER.

Study by means of 1H nuclear magnetic resonance of the oxidation process in high oleic sunflower oil and palm oil during deep-frying of fish cakes

This study aimed to compare the frying performance of palm oil (PO) and high oleic sunflower oil (HOSO) during frying aquatic products. The quality change and frying performance of HOSO and PO during frying of fish cakes were investigated. The oxidation and hydrolysis products of both oils were explored by the nuclear magnetic resonance technique. The results showed that the color deepening rate of PO was higher than that of HOSO. After 18 h of frying, the total polar compound content of PO and HOSO reached 25.67% and 27.50%, respectively. HOSO had lower degree of oxidation than PO after 24 h of continuous frying. The polyunsaturated fatty acid content in HOSO and PO significantly decreased. The oleic acid content in HOSO remained above 80% during the frying process. The major aldehydes in both oils were (E, E)-2,4-alkadienals and n-alkanals and glycerol diesters (DAGs) were abundant in PO. Furthermore, the addition of fish cakes had slight effect on the quality of the frying oil. Therefore, HOSO is an appropriate candidate for frying owing to its excellent frying stability and nutritional value.

Enhancing minority carrier lifetime in Ge: Insights from HF and HCl cleaning procedures

Efficiently passivating germanium (Ge) surfaces is crucial to reduce the unwanted recombination current in high-performance devices. Chemical surface cleaning is critical to remove surface contaminants and Ge oxides, ensuring effective surface passivation after dielectric deposition. However, Ge oxides can rapidly regrow upon air exposure. To understand the surface evolution after wet cleaning, we present a comprehensive study comparing HF and HCl deoxidation steps on p-type Ge surfaces and monitor the surface as a function of air exposure time. Distinct oxide regrowth dynamics are observed: HF-treated samples exhibit swift regrowth of all Ge oxide states, whereas HCl-treated Ge surfaces exhibit a lower concentration of low degrees of oxidation and slower or no regrowth of high oxide states even after 110 min of air exposure. In addition, the presence of Ge–Cl bonds induces different oxidation dynamics compared to the Ge–OH bonds resulting from HF cleaning. This leads to varying surface electronic band structures, with HF-treated Ge exhibiting a strong positive band bending (+0.20 eV). Conversely, HCl-treated samples display a lower band curvature (+0.07 eV), mostly due to the presence of Ge–Cl bonds on the Ge surface. During air exposure, the increased GeOx coverage significantly reduces the band bending after HF, while a constant band bending is observed after HCl. Finally, these factors induce a reduction in the surface recombination velocity after wet etching. Combining both chemical and field-induced passivation, HF-treated Ge without rinsing exceeds 800 μs.

Modifying improved-Hummer’s method to synthesize graphene derivatives from waste asphaltene

A method for synthesizing graphene derivatives from asphaltene is proposed in this work. The method is based on chemical treatment on which the asphaltene molecules are dispersed in liquid intercalating agents to remove the alkyl side chains, functionalize the aromatic core, and expand the inter-layer distance between the aromatic sheets to facilitate their exfoliation. In this intercalation process, the graphitic surface of asphaltene was oxidized to form asphaltene oxide and then graphene derivative. The results designate that the chemical treatment has caused considerable changes in aliphaticity, aromaticity, oxidation level, sulfonation range, and condensation degree. The novelty in the proposed method is envisaged by the fact that it has been tailored to selectively oxidize the asphaltene molecules and maintain its aromatic moiety. The results also confirmed that the conventional graphite oxidation treatments, such as Hummers’ Method and its subsequent improvements, are not suitable because asphaltene is far more susceptible to oxidation than graphite. The method proposed in this study, in comparison with graphite conventional oxidation methods, has less effluents of undesirable chemicals, less time, lower degree of oxidation, less weight losses, and subsequently higher yield.

Molecular Composition of Anthropogenic Oxygenated Organic Molecules and Their Contribution to Organic Aerosol in a Coastal City.

Organic aerosols (OA) have gained attention as a substantial component of atmospheric aerosols owing to their impact on atmospheric visibility, climate, and human health. Although oxygenated organic molecules (OOMs) are essential contributors to OA formation, the sources, transformations, and fates of the OOMs are not fully understood. Herein, anthropogenic OOMs (AOOMs), anthropogenic volatile organic compounds (AVOCs), and OA were concurrently measured in Xiamen, a coastal city in southeastern China. Our results show that the AOOMs exhibited a high nitrogen content (76%) and a low oxidation degree. Strong photochemical processes of aromatic VOCs were the predominant sources of AOOMs. Also, NOx concentrations and the occurrence of multigeneration OH radical oxidations were the critical factors that might influence the formation of AOOMs. Finally, the newly developed aerosol dynamic model's results show that more than 35% of the OA mass growth rate is attributed to the gas-particle partitioning of AOOMs. Further sensitivity testing demonstrates that the contribution of AOOMs to OA growth is significantly enhanced during high-particulate-concentration periods, especially under low-temperature conditions. This study emphasizes the vital role of photochemically produced AOOMs derived from AVOCs in OA growth in a coastal urban atmosphere.

Phase transition behaviors of Al nanoparticles with low oxidation degree: A molecular dynamics study

In this study, the ReaxFF reactive force field is applied to simulate the melting and annealing behaviors of aluminum (Al) nanoparticles (ANP) by molecular dynamics (MD) simulations. Potential energy, specific heat and FCC lattice number are used to study the thermal behavior of the entire phase transition process. First, the melting and solidification process of 3[Formula: see text]nm cubic Al and Al2O3 models under constant-pressure/temperature ensemble (NPT) system was simulated without boundary, and the steady-state simulation was discussed at specific temperature points. The non-boundary simulation proved the effectiveness of the Reaxff reactive force field for ANP phase transition simulations. It is confirmed that the physical properties of Al and Al2O3 could be effectively reflected in the MD simulations. ANP with low oxidation degree cannot be completely ignored in engineering applications. The existence of oxide layer hinders the annealing behavior. Therefore, this study also carried out an additional simulation process of 6 nm ANP and its oxide particles in canonical ensemble (NVT). Those obtained results show that a small amount of oxide layer can greatly change the thermal properties of ANP. If the surface of ANP is isolated, then its melting point could be increased by at least 30[Formula: see text]K.

Effects of dissolved organic matter removal and molecular transformation in different water treatment processes on formation of disinfection byproducts

Alterations in molecular composition of dissolved organic matter (DOM) during water treatments can influence the composition and toxicity of disinfection by-products (DBPs) in subsequent chlorination disinfection process. In this study, the impacts of DOM composition after various water treatment techniques (coagulation, adsorption, nanofiltration, biological aerated filter (BAF), and their integrated processes) on the generation mechanisms of DBPs were comprehensively explored by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) in combination with GC–MS and LC-MS analysis. The results indicated that coagulation preferentially removed unsaturated (low H/C) and oxidized (high O/C) compounds, whereas adsorption was prone to remove the reduced (low O/C) component that was more reactive with chlorine, leading to lower yields (μg DBP/mg DOC) of trihalomethanes (THMs) and haloacetic acids (HAAs) during subsequent chlorination. The coagulation-adsorption technique exhibited a relatively high removal of both known and unknown DBPs, demonstrating that coagulation and adsorption were complementary for DOM removal at the molecular level. Nanofiltration selectively removed molecules with relatively high O/C, however, those with very low O/C that were more reactive with chlorine could pass through the nanofiltration membrane, resulting in the highest yields of THMs and HAAs. Although BAF was inefficient in removing DBPs precursors, it could convert molecules with low degree of oxidation and unsaturation into highly oxidized and unsaturated ones, thereby significantly enhancing the removal of DBPs precursors in the subsequent coagulation-adsorption process. These findings are instrumental in developing and selecting more effective techniques to minimize the formation of DBPs in water treatment.

Humic-like Substances (HULIS) in Ship Engine Emissions: Molecular Composition Effected by Fuel Type, Engine Mode, and Wet Scrubber Usage.

Humic-like substances (HULIS), known for their substantial impact on the atmosphere, are identified in marine diesel engine emissions obtained from five different fuels at two engine loads simulating real world scenarios as well as the application of wet sulfur scrubbers. The HULIS chemical composition is characterized by electrospray ionization (ESI) ultrahigh resolution mass spectrometry and shown to contain partially oxidized alkylated polycyclic aromatic compounds as well as partially oxidized aliphatic compounds, both including abundant nitrogen- and sulfur-containing species, and clearly different to HULIS emitted from biomass burning. Fuel properties such as sulfur content and aromaticity as well as the fuel combustion efficiency and engine mode are reflected in the observed HULIS composition. When the marine diesel engine is operated below the optimum engine settings, e.g., during maneuvering in harbors, HULIS-C emission factors are increased (262-893 mg kg-1), and a higher number of HULIS with a shift toward lower degree of oxidation and higher aromaticity is detected. Additionally, more aromatic and aliphatic CHOS compounds in HULIS were detected, especially for high-sulfur fuel combustion. The application of wet sulfur scrubbers decreased the HULIS-C emission factors by 4-49% but also led to the formation of new HULIS compounds. Overall, our results suggest the consideration of marine diesel engines as a relevant regional source of HULIS emissions.

Systematical comparison of antibiotic degradation in the activated peroxymonocarbonate and Fenton systems: Kinetics, matrix influence, mechanisms and intermediate toxicities

The degradation of representative antibiotics and their mechanisms in the activated peroxymonocarbonate (PMC) and Fenton systems were systematically investigated and compared in this work. The PMC can exist and be reliable at high ratios for 1 h according to the 13C nuclear magnetic resonance spectra. The activated PMC system was proven to be more efficient than the Fenton system for the degradation of sulfamethoxazole, ciprofloxacin and ceftriaxone under same experiment conditions. The activated PMC system exhibited higher sulfamethoxazole removal performance in different actual water matrices due to the insignificant effect of coexisting substances, while the impurities had an adverse impact on the Fenton system. The pH of the activated PMC system was relatively stable and ranged from 7.8 to 8.2, while the pH of the Fenton system dropped from 5.2 to 4.1. The slight decreases of sulfamethoxazole removal efficiencies were observed after bubbling O2, N2 and CO2 in the Fenton system, while removal rates in the activated PMC system were greatly prohibited and the inhibition ratios increased with gas solubility. The selective 1O2 and CO3− played primary roles in the activated PMC system according to scavenging experiments and time-series spin-trapping electron spin resonance spectra, which resulted in higher removal efficiencies and lower oxidation degree. The non-selective OH contribution was dominant in the Fenton system. The activated PMC system was more suitable for subsequent biological treatment and friendlier to the ecosystem than the Fenton system according to intermediate pharmacophore removal and toxicity comparisons. The activated PMC system showed apparent advantages over the Fenton system in most cases, which might encourage more researchers to devote their interest and time on this promising degradation system.

Tuning the Interlayer Distance of Graphene Oxide as a Function of the Oxidation Degree for o‐Toluidine Removal

AbstractGraphene oxide (GO) with different oxidation degrees is prepared by a modified Hummers’ method varying KMnO4 amount from 0.5 to 6.0 g. X‐ray powder diffraction (XRPD), micro–Raman, thermogravimetric analysis, X‐ray photoeelectron spectroscopy, Boehm titrations, high–resolution transmission electron microscopy, and, finally, positron annihilation lifetime spectroscopy (PALS) are exploited to assess the properties of GO. Results show that increasing oxidant species can tune the interlayer gap between GO sheets up to a maximum value in the case of 4.0 g KMnO4 content. Moreover, these results validate the two‐component‐based model of GO in which, at low oxidation degree, there are unsplit/isolated graphene planes, instead at higher oxidant amounts, a five‐layer sandwiched configuration occurs comprising graphene planes having functional groups decorating the edges (bwGO), hydrated oxidative debris (OD) and “empty” spaces (revealed by PALS as the distance between (bwGO + OD) two‐component layers). In addition, by XRPD analysis, the total gap between two sheets is easily computed. In order to correlate these findings to pollutant removal capability, planar o‐toluidine adsorption is studied. Since this molecule diffuses in an aqueous environment, the obtained adsorption percentages are compared to the thickness of the hydrated OD grafted onto bwGO. A strict connection between the pollutant removal efficacy and the variation of the hydrated interlayer distance is found.

Monodisperse oxidative-sensitive polymer nanoparticles from dispersion polymerization of N-acryloyl thiomorpholine

Aqueous emulsion or suspension polymerizations are well established industrial processes with widespread applications. Dispersion polymerizations, on the contrary, are rarely found for the preparation of stable particle dispersions, which is certainly related to the limited number of suitable monomers. Here, we report that N-acryloyl thiomorpholine (NAT) is an interesting candidate for aqueous dispersion polymerizations, as it is fully miscible with water but forms insoluble polymers at low degrees of polymerization. Polymerization in pure water results in an uncontrolled precipitation but with the addition of a surfactant well-defined dispersions with monomodal size distributions are obtained if low monomer concentrations (≤4 wt%) are used. Higher concentrations (10 wt%) broaden the dispersity of the resulting particles, but still result in stable dispersions, while 30 wt% cause a solidification of the solution as particles start to fuse. Crosslinked particles can be obtained by addition of a bisacrylamide comonomer. The thioether moiety of NAT further enables postpolymerization modifications including its oxidation to a more polar sulfoxide. Kinetic studies revealed that oxidation in H2O2 follows a bulk process causing a swelling of the particles after reaching a critical degree of oxidation (35%). In case of the non-crosslinked particles, disintegration occurs only at ≥ 60% conversion of the thioethers, while the particles remain intact for days at lower degrees of oxidation. The oxidation of the crosslinked particles results in water-swollen microgels. Overall, the straightforward process allows access to monodisperse reactive polymer nanoparticles of variable size (∼ 60 – 100 nm) that could be used as well-defined templates or carrier materials.

New insights into the mechanism of phosphate release during particulate organic matter photodegradation based on optical and molecular signatures

Phosphate release from particulate organic matter (POM) dominates phosphorus (P) cycling in aquatic ecosystems. However, the mechanisms underlying P release from POM remain poorly understood because of complex fractionation and analytical challenges. In this study, the release of dissolved inorganic phosphate (DIP) during POM photodegradation was assessed using excitation–emission matrix (EEM) fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). POM in suspension was significantly photodegraded under light irradiation, concomitantly with the production and release of DIP in the aqueous solution. Chemical sequential extraction revealed that organic phosphorus (OP) in POM participated in photochemical reactions. Moreover, FT-ICR MS analysis revealed that the average molecular weight of P-containing formulas decreased from 374.2 to 340.1 Da. Formulas containing P with a lower oxidation degree and unsaturation were preferentially photodegraded, generating oxygen-enriched and saturated formula compounds, such as protein- and carbohydrate-like P-containing formulas, benefiting further utilization of P by organisms. Reactive oxygen species played an important role in the photodegradation of POM, and excited triplet state chromophoric dissolved organic matter (3CDOM*) was mainly responsible for POM photodegradation. These results provide new insights into the P biogeochemical cycle and POM photodegradation in aquatic ecosystems.

Oxidation stability of oil-in-water emulsion prepared from perilla seed oil and soy sauce with high salt concentration using OSA-starch.

The O/W emulsions were prepared using perilla seed oil (PSO) dispersed in soy sauce (PSE) and in distilled water (PWE), respectively. Octenyl succinic anhydride-modified starch (OSA starch, 3 wt%) showed the most efficient emulsifying ability and its stabilities of emulsion and oxidation in PSE and PWE were studied at different storage periods (0, 4, and 8weeks) and temperatures (4, 25, and 40°C). Negligible change in droplet diameter of PSE was observed without coalescence or flocculation during storing for 8weeks at 4°C. The stabilizing ability of OSA-starch despite the high ionic strength of soy sauce is attributed to the starch backbone, which promotes steric repulsions between droplets. A lower oxidation degree was observed for PSE prepared than PWE and PSO under all storage conditions. Thus, the O/W emulsion prepared from PSO and soy sauce can be applied to the production of ω-3 fatty acid-enriched Asian-style emulsified products.

Anatomy of rocky planets formed by rapid pebble accretion

We present a series of papers dedicated to modelling the accretion and differentiation of rocky planets that form by pebble accretion within the lifetime of the protoplanetary disc. In this first paper, we focus on how the accreted ice determines the distribution of iron between the mantle (oxidized FeO and FeO1.5) and the core (metallic Fe and FeS). We find that an initial primitive composition of ice-rich material leads, upon heating by the decay of26Al, to extensive water flow and the formation of clay minerals inside planetesimals. Metallic iron dissolves in liquid water and precipitates as oxidized magnetite Fe3O4. Further heating by26Al destabilizes the clay at a temperature of around 900 K. The released supercritical water ejects the entire water content from the planetesimal. Upon reaching the silicate melting temperature of 1700 K, planetesimals further differentiate into a core (made mainly of iron sulfide FeS) and a mantle with a high fraction of oxidized iron. We propose that the asteroid Vesta’s significant FeO fraction in the mantle is a testimony of its original ice content. We consider Vesta to be a surviving member of the population of protoplanets from which Mars, Earth, and Venus grew by pebble accretion. We show that the increase in the core mass fraction and decrease in FeO contents with increasing planetary mass (in the sequence Vesta – Mars – Earth) is naturally explained by the growth of terrestrial planets outside of the water ice line through accretion of pebbles containing iron that was dominantly in metallic form with an intrinsically low oxidation degree.