Moderate Content Research Articles

Effects of Fe and Li2MnO3‐like domains on structural stability in Co‐free Li‐rich layered oxide cathodes

AbstractThe aggregation of Li2MnO3‐like domains in Li‐rich layered oxides (LLOs) causes severe capacity/voltage fading, which seriously impedes their commercial applications. Here, we design Co‐free Li‐rich LiFeNiMnO system with dispersed small‐sized Li2MnO3–like domains (D‐LFNMO) and aggregated Li2MnO3‐like domains (A‐LFNMO) to investigate effects of Li2MnO3‐like domain sizes and Fe content on structures and oxidation process using density function theory (DFT) calculations. De‐lithiation structures, structural stability and oxidization mechanism of lattice oxygen ions are explored. Structural stability is finished through calculating oxygen release energies and migration energy barriers of Mn4+ ions based on a climbing image nudged elastic band (CI–NEB) method. Research shows that LLOs with dispersed small‐sized Li2MnO3‐like domains and the moderate Fe content would possess highly reversible oxygen redox and excellent structural stability and would exhibit superior cycling stability of high capacity. The findings provide new perspectives and concepts for designing high‐energy Li‐rich cathodes.

Quality, reliability, and content of YouTube videos in Portuguese language about dental trauma

Objective: To evaluate the quality, reliability and content of YouTube videos in Portuguese about dental trauma. Method: An infodemiological study was developed in which the first 60 videos found on YouTube with the terms “dental traumatism”, “dental trauma” and “broken tooth” were analyzed. Repeated videos, longer than one hour, in a language other than Portuguese, not intended for the lay public, resolution of questions, songs, interviews, shorts, and other subjects were excluded. The content of the videos was rated using a 23-point scale that classified them into low, moderate, and high content. Reliability was assessed using the modified DISCERN scale and the overall quality was assessed using the Global Quality Score (GQS) scale. The numbers of likes, dislikes, comments and engagement were also accounted. Data were analyzed by Mann-Whitney and Spearman’s correlation test (α= 5%). Result: A total of 55 videos were included in the study. Most were posted by healthcare professionals (92.7%) and just over half (63.7%) were of good overall quality. There were moderate, positive, and statistically significant correlations between DISCERN and GQS scores (r=0.454), duration (r=0.575), and trauma content (r=0.510). Overall quality correlated moderately, positively, and significantly with content scores (r=0.604) and video length (r=0.467). Conclusion: A significant proportion of Portuguese videos on YouTube about dental trauma had low content, quality and reliability information.

Size-progressively-reduced FeCoNi@C nanoparticles spatially confined within polypyrrole-derived hollow carbon nanoboxes against electromagnetic contamination

Pyrolytic prussian blue analogues (PBAs) are usually faced with serious agglomeration problem, which restrains their application in the field of microwave absorption to some extent. Given that polymer-based encapsulating layer is propitious for resolving the above issue, herein, with the assistance of polypyrrole (Ppy), a series of carbon-coated FeCoNi alloy nanoparticles (FeCoNi@C) spatially confined within hollow carbon nanoboxes (HCNB) are successfully fabricated using FeCoNi PBAs@Ppy with core–shell structure as the precursors. By quantitatively manipulating the thickness of Ppy encapsulating layer, it is found that there exists a competitive correlation between two kinds of forces with opposite directions under high-temperature inert atmosphere, eventually resulting in distinguishable differences in the configurations of derivatives. Specifically, if the thermal-induced inward contraction (FC) of the inner FeCoNi PBAs core is stronger than the heterointerface interaction (FI) provided by interfacial carbon layer derived from the outer Ppy shell, the derivative will exhibit yolk-shell microstructure, and otherwise, the architecture with hollow configuration can be created. When the thickness of Ppy encapsulating layer is optimized, the resultant yolk-shell sample with moderate Ppy-derived carbon content (ca. 32.6 wt%) delivers a broad maximum effective absorption bandwidth (EAB) value of 5.8 GHz and a desirable minimum reflection loss (RL) intensity of − 52.4 dB, which mainly benefit from its eligible impedance matching characteristic and the synergistic effect of dielectric and magnetic losses. It is believed that this work will enrich the pertinent researches about microwave absorbing materials (MAMs) with outstanding performance derived from polymer-encapsulated PBAs.

A formation pathway for terrestrial planets with moderate water content involving atmospheric-volatile recycling

Of the many recently discovered terrestrial exoplanets, some are expected to harbor moderate water mass fractions of a few percent. The formation pathways that can produce planets with these water mass fractions are not fully understood. Here, we use the code chemcomp which consists of a semi-analytical 1D protoplanetary disk model harboring a migrating and accreting planet, to model the growth and composition of planets with moderate water mass fractions by pebble accretion in a protoplanetary disk around a TRAPPIST-1 analog star. This star is accompanied by seven terrestrial planets, of which the outer four planets likely contain water mass fractions of between 1<!PCT!> and 10<!PCT!>. We adopt a published model that considers the evaporation of pebbles in the planetary envelope, from where recycling flows can transport the volatile vapor back into the disk. We find that with this model, the planetary water content depends on the influx rate of pebbles onto the planet. A decreasing pebble influx with time reduces the envelope temperature and consequently allows the formation of planets with moderate water mass fractions as inferred for the outer TRAPPIST-1 planets for a number of different simulation configurations. This is further evidence that the recycling of vapor is an important component of planet formation needed to explain the vast and diverse population of exoplanets.

Mind the gap: Distinguishing disc substructures and their impact on the inner disc composition

Improved observational technologies have enabled the resolution of substructures and the measurement of chemical abundances in protoplanetary discs. Understanding the chemical composition of the inner disc allows us to infer the building blocks available for planet formation. Recently, the depletion of water in the inner disc has been suggested to be linked to the presence of substructures, such as gaps and rings, further out in the disc. We investigate this hypothesis further by running 1D semi-analytical models of a protoplanetary disc with a gap to understand the combined effects of disc viscosity, gap depth, gap location, and gap formation timescales on the composition of the inner disc (water abundance, C/O, O/H, and C/H ratios). Our results show that for a specific value of disc viscosity, the simulation outcome can be classified into three regimes: shallow gap, 'traffic jam', and deep gap. While deep gaps may already be distinguishable with moderate-resolution (FWHM sim 10 AU) techniques, it is still challenging to resolve shallow gaps with the current capabilities. On the other hand, discs with traffic jams have a higher chance of being resolved when observed with a high resolution (FWHM lesssim 5 AU), but they may appear as an intensity enhancement or even featureless when observed with moderate to low angular resolution (FWHM gtrsim 10 AU). In this regard, information on the inner disc composition is useful because it can help to infer the existence of traffic jams or distinguish them from deep gaps: discs with deep gaps are expected to have a low water content -- and thus high C/O ratio in the inner disc due to the effective blocking of pebbles -- while discs with shallow gaps would demonstrate the opposite trend (water-rich and low C/O ratio). Furthermore, discs with a traffic jam would have a constant (albeit low) inward flux of water-rich pebbles resulting in a moderate water content and sub-stellar C/O ratios. Finally, we find that the effectiveness of gaps as pebble barriers diminishes quickly when they form late $(t_ gap Myr )$, as most of the pebbles have already drifted inwards.

Effect of Inconel 718 Filler on the Microstructure and Mechanical Properties of Inconel 690 Joint by Ultrasonic Frequency Pulse Assisted TIG Welding.

Ultrasonic frequency pulse assisted TIG welding (UFP-TIG) experiments were conducted to join Inconel 690 alloy (IN690) by adding Inconel 718 alloy (IN718) as the filler. The effect of the filler on the microstructure, mechanical properties, and ductility dip cracking (DDC) susceptibility of IN690 joints were investigated. The results show that a variety of precipitates, including MC-type carbide and Laves phases, are formed in the weld zone (WZ), which are uniformly dispersed in the interdendritic region and grain boundaries (GBs). The increase in the thickness of the IN718 filler facilitates the precipitation and growth of Laves phases and MC carbides. However, the formation of Laves phases in the WZ exhibits a lower bonding force with the matrix and deteriorates the tensile strength of IN690 joints. Due to the moderate content of Laves phases in the WZ, the IN690 joint with 1.0 mm filler reaches the maximum tensile strength (627 MPa), which is about 96.5% of that of the base metal (BM). The joint with 1.0 mm filler also achieves the highest elongation (35.4%). In addition, the strain-to-fracture tests indicate that the total length of cracks in the joint with the IN718 filler decreases by 66.49% under a 3.8% strain. As a result, the addition of the IN718 filler significantly improves the mechanical properties and DDC resistance of IN690 joints.

Studies on the Nutritional, Minerals, Mineral Ratio, Anti-nutritional, Molar Ratio and Antioxidant Compositions of Four Selected Leafy Wild Vegetables in Ado-Ekiti, Ekiti State, Nigeria

The study investigated the nutritional, mineral Anti-nutritional factors, molar ratios and antioxidants compositions in the leaves of four selected wild edible vegetables (Piper guinensis, Piper umbelatum, Celosia argentia and Jatropha tajorensis) collected in Ado Ekiti, Ekiti State, Nigeria. The proximate, minerals and anti-nutrient compositions of the samples were determined using standard procedures. Also antioxidant activity of the samples were detected using standard assays such as 1, 1, diphenyl-2-2 picrylhydrazyl (DDPH) and Ferric Reducing Antioxidant Potential (FRAP).The mineral ratio, molar ratio and Mineral Safety Index were calculated from mineral results. The results of the proximate compositions for the four wild vegetables for moisture content, ash, crude fat, crude fiber, crude protein and carbohydrate ranged from 11.16 - 12.15%, 2.76-4.03%, 4.07 -7.31%, 13.33-16.73%, 7.36 – 10.09%, and 52.09 -58.22% respectively,. The results of the mineral composition revealed high content of K, moderate content of Ca, P, and low contents of Mg, Fe, Zn, Cu and very low concentrations of Pb and Ni. Cd was absent in all the samples investigated. Zn/Cu and Fe/Cu ratios indicated low copper load. Antinutrients factors in the vegetable were low with the exception of phytate which can be reduced to non-toxic level through boiling or cooking. The calculated mole ratio for [Phy][Zn], [Ca]/[Phy], [Phy]/[Fe] and [Ca][Phy]/[Zn] conformed with the standard values. The results of the antioxidant properties showed that the wild vegetables are good natural antioxidant sources. The assessment of the vegetables showed that they are rich sources of crude protein, crude fiber and carbohydrate with high energy calories. The mineral ratios and mineral safety index suggested that the minerals could not pose any mineral load to human body. Hence, the vegetables could be explored as supplement diet for man. The vegetables could provide the needed nutrition health benefit and also help in addressing the problem of food security in Nigeria.

Late Cenozoic high and low temperature magma generation from primordial and age-modified mantle materials beneath Dariganga in Southeast Mongolia: Factors of mantle degassing and adiabatic upwelling

Representative sampling of the Dariganga volcanic field was conducted to decipher its inner structure in terms of its deep magma sources. Rocks with a high La/Yb ratio (40–54) and a high MgO content (11–15.8 wt%) are identified among the predominantly moderate La/Yb ratio (7–40) and a moderate MgO content (5–11 wt%) rocks. These rock markers, traced along linear volcanic zones, are considered as indicators of high and low temperature magma generation processes. A general agreement exists that partial melting predominated in the transitional asthenosphere–lithosphere region; however, between 10 and 5 Ma, these processes were complicated by melts that either adiabatically ascended from a residual slab source in the deep mantle at a high potential temperature (Тр = 1489°С) or were generated due to mantle fluid degassing at a low temperature or both these processes, simultaneously. Magmas were subsequently adiabatically upraised from an OIB-like source in the deep mantle with potential temperatures (Tp) of up to 1423°C and were also generated by mantle fluids at low temperature. The rock markers yield Pb-isotope age estimates of the proto-mantle (at 4.47 and 4.45 Ga) and the age-modified mantle (at 3.11 and 2.74 Ga) beneath Dariganga. In the last 16 Ma, encompassing the late geodynamic epoch of Earth's mantle, similar high and low temperature magmas have erupted across vast sections of the Japan-Baikal Geodynamic Corridor; these magmas are not reported from the adjacent Abaga and Dalinuoer areas, with the exception of the final (Holocene) fluid-derived compositions.

The Governance, Legitimacy and Efficacy of Facebook's Oversight Board: A Model for Global Tech Platforms?

In May 2020, the social media giant Meta, parent company of social media platforms Facebook and Instagram, established an Oversight Board to allow some recourse to the content moderation policy of the company. The Oversight Board is an experiment in self-regulation (where ‘self’ refers to the company, not industry) by one of the global platforms to address content regulation. The Board is structured on the ‘arm's length principle’ to ensure independence from Meta. This paper analyses the structure for legitimacy and takes a bird's eye view of the decisions that have been made to date for efficacy. Of the more than 100 decisions by the Board, a total of 80% had been overturned. Interestingly, the percentage of overturned decisions has been increasing. This study suggests that the company was indeed not able to handle decisions around content well by itself. Further, the Board reported the need to increase the answerability and comprehensiveness of Meta to its recommendations. The paper suggests a shift in the tone of the global debate on content moderation from a near-absolutist position against moderation to a willingness to consider content governance. It concludes that while there is room for improvement, the structure could serve as a model for other companies that face a similar need to moderate content globally.

Catalytic oxidation of SO2 in O2-aerated aqueous Solution: superior catalytic capability of KOH/urea-treated biochars and catalytic mechanism

The catalytic oxidation of SO2 (COS) by dissolved oxygen in aqueous solution allows to recycle sulfate salt/sulfuric acid from the SO2-containing flue gas, and high-performance catalysts are desired for an efficient COS process. In this study, the chestnut leaves-derived biochars treated by the co-pyrolysis process with KOH/urea exhibited a favorable capability to catalyze the oxidation of SO2 in aqueous solution. The BK-N-8 biochar catalyst was the optimal one due to its moderate nitrogen content and appropriate surface functional groups. It exhibited a fast initial conversion rate from SO2 to SO42− (6.50 μmol g−1 s−1), and an excellent cycling durability for the COS process. The material showed a catalytic activity that surpassed all the reported carbonaceous materials. The surface functionalities were revealed to be the decisive factor for the conversion rate and durability of catalytic capacity. The superiority of the BK-N-8 with pyridinic N-doped aromatic cluster (AC) was further investigated via density-functional-theory calculations. The epoxy groups from O2 dissociation at the edge sites of ACs played a pivotal role for COS process onto biochars. This study provides insightful information for an in-depth understanding of the mechanism of COS process catalyzed by carbonaceous materials.

Achieving the hardness-ductility balance of laser quenching process via thermal cycling

The imperfect ductility of laser quenched component is challenging the application of laser quenching process ignoring the excellent hardness performance. In the present work, the “drawback” thermal cycling is employed to achieve the hardness-ductility balance via in-situ tempering the as-quenched microstructure. The extremely non-isothermal condition of thermal cycling induces the partial recovery/recrystallization of martensite, precipitation of refined cementite and limited decomposition of retained austenite. A superior combination of the 184 % increase of hardness, 28.19 % improvement of strength and almost equivalent elongation of the laser quenched component are achieved. The tempered martensite decorated with sub-micron grain size, moderate carbon content and dislocation density contributes to the high hardness and strength. The softening recrystallized martensite and released retained austenite enhance the plastic deformation ability by dislocation absorption. Associated with the enhanced inhibition of microcrack propagation from the fine cementite, the ductility of laser quenched component is greatly improved. The thermal cycling provides an opportunity for the laser quenching process to be applied to the surface strengthening of axle.

Elucidating the deformation characteristics of Ti–Ni–Fe based pseudo-binary B2 intermetallics

The room temperature uniaxial compression behavior of homogenized Ti50Ni50-xFex (5≤x ≤ 45) pseudo-binary B2 intermetallics has been investigated. The compressive stress-strain curves of these intermetallics exhibited three different characteristics (a) intermetallics with low Fe content (i.e., Ti50Ni45Fe5 and Ti50Ni40Fe10): exhibited stress induced martensite (SIM) transformation (B2 → B19 ') (marked by a plateau with non-linear elastic regime) followed by significant plastic deformation up to ∼ 40 % strain marked with significant strain hardening, (b) intermetallics with moderate Fe content (Ti50Ni35Fe15) showed no SIM transformation, but a typical smooth elastic-plastic transition with maximum strain to failure of ⁓ 11–12 % was observed, and (c) intermetallics with high Fe content (≥ 25 at. %) displayed a very small strain to failure (≤ 5 %) without visible plastic deformation. The TEM and XRD analysis of the deformed (15 % and 40 % strain) Ti50Ni45Fe5 and Ti50Ni40Fe10 intermetallics indicated the presence of internally twinned martensite variants (MVs) along with severely dislocated banded B2 matrix. The observed contrast in the deformation characteristics has been attributed to the variation in the values of elastic constants (C' and C44) and Zener anisotropy (A) with Fe content. The SIM transformation in Ti50Ni45Fe5 and Ti50Ni40Fe10 occurred at lower values of C' and C44 (due to elastic softening) and relatively low Zener anisotropy A. The significant plastic strain in these two intermetallics was accommodated by the presence and deformation of super intrinsic stacking faults (SISFs) formed by dissociation of 12⟨111⟩ screw super-partials. In contrast, the deformation in the intermetallics with high Fe content (≥ 25 at. %) was governed by the activation of ⟨100⟩ screw dislocations.

Cubeb (Piper cubeba L.): nutritional value, phytochemical profiling and dermacosmeceutical properties.

Cubeb, Piper cubeba L., has been used for centuries in traditional medicine and culinary practices, with a wide range of biological and pharmacological activities. Herein, we determined the phytochemical profile, mineral, fatty acids, and amino acid contents of P. cubeba berries and assessed the dermacosmeceutical properties of their water extract and essential oil (EO). These included assessing their antioxidant and antibacterial activities as well as their in vitro inhibitory activities against tyrosinase and elastase enzymes. In addition, molecular docking and molecular dynamics studies were performed on the major identified compounds of the EO. A total of forty-three compounds belonging to organic acids, phenolic acids and flavonoids were found in the water extract, while 36 volatile compounds were identified in the EO with Z-isoeugenol, dihydroeugenol, β-pinene, E-caryophyllene, and 1,8-cineole as major constituents. The berries were found to be rich in sodium and iron, have moderate zinc content along with low contents of total nitrogen, phosphorus, and potassium. Amino acid analysis revealed a considerable concentration of isoleucine and phenylalanine, whereas 11,14,17-eicosatrienoic acid and linoleic acid were identified as the major fatty acids. In the DPPH and FRAP assays, the water extract elicited considerable antioxidant activity compared to the reference compounds. Enzyme inhibitory assays revealed that the EO had a potential to inhibit tyrosinase and elastase enzymes with IC50 values of 340.56 and 86.04 μg/mL, respectively. The water extract and EO completely inhibited the bacterial growth at MIC of 50 mg/mL and 20%, respectively. At sub-MIC concentrations, the extract and the EO substantially reduced the biofilm formation by up to 26.63 and 77.77%, respectively, as well as the swimming and swarming motilities in a dose-dependent manner. Molecular docking and molecular dynamics showed that the five main components of P. cubeba EO could be the major contributors to the elastase and tyrosinase inhibitory effect. This study emphasizes the promising potential of P. cubeba as a valuable source of natural compounds that can be utilized for the development of innovative pharmaceuticals, dietary supplements, and dermacosmeceutical agents.

Effect of the proportion of stevia leaf extract (Stevia rebaudiana B) on the chemical characteristic properties of functional pudding

Functional pudding, a popular dessert, has attracted attention in recent years due to its potential as a vehicle for delivering health-promoting ingredients. This study investigates the impact of different proportions of stevia leaf extract (Stevia rebaudiana B) on the physicochemical properties of functional pudding. Stevia leaf extract, known for its natural sweetness and negligible impact on blood sugar levels, holds promise as a low-calorie alternative to traditional sweeteners. Through systematic experimentation, various concentrations of stevia leaf extract are incorporated into pudding formulations, and their effects on water content, ash content, fat content, protein content, and carbohydrate content are evaluated. The results indicate significant alterations in the physicochemical characteristics of the pudding samples, with variations observed in water content, ash content, fat content, protein content, and carbohydrate content. Specifically, sample F6, containing the highest proportion of stevia leaf extract, exhibits notable changes, including a high-water content of 88.31%, low ash content of 0.49%, moderate fat content of 0.81%, elevated protein content of 5.35%, and reduced carbohydrate content of 5.02%. These findings underscore the potential of stevia leaf extract as a functional ingredient in pudding formulations and provide insights for the development of healthier dessert options.

Molecular Diversity and Combining Ability in Newly Developed Maize Inbred Lines under Low-Nitrogen Conditions.

Nitrogen is an essential element for maize growth, but excessive application can lead to various environmental and ecological issues, including water pollution, air pollution, greenhouse gas emissions, and biodiversity loss. Hence, developing maize hybrids resilient to low-N conditions is vital for sustainable agriculture, particularly in nitrogen-deficient soils. Combining ability and genetic relationships among parental lines is crucial for breeding superior hybrids under diverse nitrogen levels. This study aimed to assess the genetic diversity of maize inbred lines using simple sequence repeat (SSR) markers and evaluate their combining ability to identify superior hybrids under low-N and recommended conditions. Local and exotic inbred lines were genotyped using SSR markers, revealing substantial genetic variation with high gene diversity (He = 0.60), moderate polymorphism information content (PIC = 0.54), and an average of 3.64 alleles per locus. Twenty-one F1 hybrids were generated through a diallel mating design using these diverse lines. These hybrids and a high yielding commercial check (SC-131) were field-tested under low-N and recommended N conditions. Significant variations (p < 0.01) were observed among nitrogen levels, hybrids, and their interaction for all recorded traits. Additive genetic variances predominated over non-additive genetic variances for grain yield and most traits. Inbred IL3 emerged as an effective combiner for developing early maturing genotypes with lower ear placement. Additionally, inbreds IL1, IL2, and IL3 showed promise as superior combiners for enhancing grain yield and related traits under both low-N and recommended conditions. Notably, hybrids IL1×IL4, IL2×IL5, IL2×IL6, and IL5×IL7 exhibited specific combining abilities for increasing grain yield and associated traits under low-N stress conditions. Furthermore, strong positive associations were identified between grain yield and specific traits like plant height, ear length, number of rows per ear, and number of kernels per row. Due to their straightforward measurability, these relationships underscore the potential of using these traits as proxies for indirect selection in early breeding generations, particularly under low-N stress. This research contributes to breeding nitrogen-efficient maize hybrids and advances our understanding of the genetic foundations for tolerance to nitrogen limitations.

Enrichment mechanism of organic matter and silicon in lower Cambrian shale of the Yangtze Platform

Early Cambrian time witnessed accumulation of high-quality organic-rich siliceous shale deposits that comprise an especially promising shale gas exploration target, especially in China. The present study of the Cambrian Niutitang Formation of the shelf area of the Upper Yangtze Platform utilizes mineralogical and elemental geochemical data to aide in the paleoenvironment reconstruction of these organic-rich deposits. We are especially interested in elucidating organic carbon and silicon enrichment mechanisms of the Niutitang Formation that will benefit shale gas exploration and development of these deposits. The Niutitang Formation can be subdivided into three intervals based on lithology, gamma ray (GR) signature, and TOC abundance. Enriched TOC (average = 6.7%) and nano-size authigenic microcrystalline quartz (Qn) contents of Interval I deposits likely reflect deposition in an environment that experienced persistent euxinic and elevated organic matter delivery associated with enhanced paleoproductivity driven by hydrothermal activity. Interval II shale is interpreted to have accumulated under euxinic-ferruginous conditions that experienced the effects of robust paleoproductivity and diminished terrigenous input related to persistently warm, humid climatic conditions. Enriched TOC (average = 4.9%) and moderate microcrystalline quartz content of these deposits were likely the result of redox conditions and elevated paleoproductivity. Interval III strata appears to have accumulated under oxygenated bottom conditions that experienced moderate paleoproductivity, brackish water and elevated terrigenous detritus input driven by the establishment of cold, dry climatic conditions. The combined results of these conditions are diminished TOC content (average = 0.7%) and enrichment of the sediment in terrestrial quartz. The elevated content of authigenic quartz appears to have diminished the reservoir capacity of Niutitang Formation shale. Interval II organic-rich siliceous shale deposits of Upper Yangtze Platform shelf areas, which have the comparable authigenic microcrystalline quartz content, reservoir performance, and greater organic matter abundance as the rift trough, appear to comprise the stratigraphic horizon with the greatest exploration and development potential. Results of the present study offer theoretical guidance for future shale gas exploration and development efforts in geologically similar regions.

Effects of porous structure and oxygen functionalities on electrochemical synthesis of hydrogen peroxide on ordered mesoporous carbon

Two-electron oxygen reduction reaction (2e− ORR) is a promising alternative to energy-intensive anthraquinone process for hydrogen peroxide (H2O2) production. Metal-free nanocarbon materials have garnered intensive attention as highly prospective electrocatalysts for H2O2 production, and an in-depth understanding of their porous structure and active sites have become a critical scientific challenge. The present research investigates a range of porous carbon catalysts, including non-porous, microporous, and mesoporous structures, to elucidate the impacts of porous structures on 2e− ORR activity. The results highlighted the superiority of mesoporous carbon over other porous materials, demonstrating remarkable H2O2 selectivity. Furthermore, integration of X-ray photoelectron spectroscopy (XPS) data analysis with electrochemical assessment results unravels the moderate surface oxygen content is the key to increase 2e− ORR activity. These results not only highlight the intricate interplay between pore structure and oxygen content in determining catalytic selectivity, but also enable the design of carbon catalysts for specific electrochemical reactions.

On the radiometric significance of glauconies in studies of provenance: An example of the quaternary marine sequences of the Rio Grande Cone (Pelotas basin, southern Brazil)

The sediments of the Pleistocene-Holocene marine sequences of the Rio Grande Cone (RGC) (offshore Pelotas Basin, southernmost Brazilian Margin) are dominantly composed by muddy facies with thin interspersed sandy layers containing abundant very fine-to coarse green grains, heavy minerals assemblage, shards and planktonic foraminifera. These components contribute for a better understanding of the RGC filling during the Pleistocene-Holocene. However, the aim of this work was focused in the radiometric dating of the green grains as tool for provenance studies in marine sedimentary sequences. Based on Electron Microprobe, Scanning Electron Microprobe, Transmission Electron Microprobe and optical analysis the green grains occur as: (01) yellowish-green grains with smooth surfaces, low K2O and moderate Fe2O3 contents, (02) pale green grains with surfaces slightly fractured with moderate K2O and Fe2O3 contents, and (03) dark green grains characterised by fractured (cracked) surfaces and high of K2O and Fe2O3 contents. These characteristics classified them as glauconitic minerals ranging from glauconitic smectite to glauconitic mica (glauconite) indicating the first (nascent) and intermediate (slightly-evolved and evolved) stages of the glauconitization process. K–Ar radiometric dating indicated ages from 33.2 ± 0.99 to 6.69 ± 0.54 Ma corresponding from Rupelian Stage (Oligocene) to Messinian Stage (Miocene) to these grains. Considering these glauconitic grains within a Quaternary sequence, an allochthonous (detrital) origin was attributed whose probable source areas were older sedimentary sequences exposed on the seafloor along fold-and-thrust belts related to the gravitational collapse of the RGC depocentre. After eroded the glauconitic minerals probably were distributed by countourite currents and deposited within the Quaternary deposits of the RGC.

MnO@Mn2O3 nanocrystals embedded in biochar networks for sustainable anode of lithium-ion batteries

MnO is an alternative for commercial graphite as anode material for lithium-ion batteries (LIBs), if the issue of unstable performance caused by volume changes, poor conductivity, and changes in valence state of Mn is addressed. In this study, a series of nano MnO/biochar-containing composite materials were prepared with Mn(NO3)2, urea and pomelo peel as raw materials, via simple hydrothermal treatment and calcination, as anode materials for LIBs, where the biochar was used as inexpensive conductive medium and volume buffer. The electrochemical performance of the composite materials shows complicated correlation with the biochar contents, which associate with different carbonization temperatures. Elaborate characterizations with XRD, SEM, TEM, and Mn 2p, Mn 3s XPS spectra were conducted and jointly analyzed, which revealed that the surface of MnO nanocrystals undergoes different degrees of oxidation. The thickness of the surface amorphous Mn2O3 layer on the MnO nanocrystals influences the long-term electrochemical stability more significantly than the circumstances of biochar encapsulation, which was proved through cyclic voltammetry (CV) measurements. A composite material with moderate biochar content and thin layer of Mn2O3 coating on MnO nanocrystals will show more stable electrochemical performance. Based on this principle, one regulated composite material (MnOx/BC-650) gives an ultra-stable capacity of 446.9 mAh∙g−1 at 500 mA∙g−1 after 200 cycles. This study provides new insight for both revealing the true structure of manganese oxides and developing long-term stable MnO-containing anode materials for LIBs.

Crystal facet engineering of K-OMS-2 for active site identification in catalytic ozone decomposition

Manganese oxide catalysts (MnOx) are expected to be utilized to catalytic ozone (O3) decomposition to curb indoor O3 pollution. However, the accumulation of oxygen-containing species (*OO) on the active site (oxygen vacancy, Ov) of MnOx limits the practical application. Herein, α-MnO2 with exposed {100} (Mn-100), {110} (Mn-110), or {310} (Mn-310) facet was synthesized, respectively. Mn-110 has preferred performance and stability, maintaining 99.9 % O3 conversion after 8 h under 35 % RH. Experimental and theoretical results indicated that the Mn-100 facet owns lower Ov content and *OO adsorption energy, exhibiting the highest specific area normalized activity. Mn-310 has a higher vacancy content and enhanced *OO adsorption energy, which resulted in a rapid accumulation of *OO species. Mn-110 has a moderate Ov content and *OO adsorption and thus exhibits optimal activity. This study hopes to point out a new optimization strategy for MnOx catalysts.