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The origin and evolution of sponges have attracted interest, not only because they are among the most basal metazoans, but also because they act as important ecological engineers in the ocean. Previous research suggested that sponge groups diversified quickly during the Cambrian Series 2, while Terreneuvian sponge fossils are conspicuously rare and poorly substantiated. Yet, an increasing number of sponge spicules have been reported from the Ediacaran-Cambrian (E-C, ca. 551–523 Ma) transitional carbonates/cherts worldwide, particularly in South China, which calls for updated discussions. Ocean oxygenation has been widely proposed to play a critical role in organismal evolution, but its relationship with sponges is unclear and falls into a "chicken-egg" dilemma. In this study, we summarize reported sponge spicule distributions from five E-C sections in South China to investigate the early evolutionary pattern of siliceous sponges. According to current stratigraphic correlation, monaxons first appear in the late Ediacaran in the intrashelf basin-slope area, and then potentially expand to the continental shelf and deep basin in the lower Cambrian. In these sections, the abundance, size, and diversity of monaxons increase upwards, followed by the appearance of diaxons, triaxons and then polyactines. Despite the uncertain affinity of the sponge fossils, it is possible that siliceous hexactinellids evolved later than siliceous demosponges, given that the earliest spicule assemblages are exclusively composed of monaxons, which commonly form bundles comparable to modern demosponges. New geochemical data from the Sifangjing section, Guizhou Province and the Yanziqiao section, Hunan Province, South China show that the appearance of sponges usually corresponds to anoxic environment. In addition, we applied the recently proposed Biological Pump, Oxygen and Phosphorus (BPOP) model to trace the evolution of oceanic oxygen concentrations with the radiation of sponges. The results indicate that the possible contribution of sponges to oxygenation of the deep ocean was limited. [ABSTRACT FROM AUTHOR]

Whether metazoan diversification during the Cambrian Radiation was driven by increased marine oxygenation remains highly debated. Repeated global oceanic oxygenation events have been inferred during this interval, but the degree of shallow marine oxygenation and its relationship to biodiversification and clade appearance remain uncertain. To resolve this, we interrogate an interval from ~527 to 519 Ma, encompassing multiple proposed global oceanic oxygenation events. We integrate the spatial and temporal distribution of shallow water, in situ reef metazoans, and trilobites, with high-resolution multi-proxy redox data through the highly biodiverse Siberian Platform. We document primarily dysoxic water column conditions, suggesting that early Cambrian metazoans, including motile skeletal benthos, had low oxygen demands. We further document oxygenation events coincident with positive carbon isotope excursions that led to modestly elevated oxygen levels. These events correspond to regional increases in species richness and habitat expansion of mainly endemic species, offering a potentially globally applicable model for biodiversification during the Cambrian Radiation. [ABSTRACT FROM AUTHOR]

Understanding the diurnal and seasonal regulation of photosynthesis is an essential step to quantify and model the impact of the environment on plant function. Although the dynamics of photosynthesis have been widely investigated in terms of CO2 exchange measurements, a more comprehensive view can be obtained when combining gas-exchange and chlorophyll fluorescence (ChlF). Until now, integrated measurements of gas-exchange and ChlF have been restricted to short-term analysis using portable infrared gas analyzer systems that include a fluorometer module. In this communication we provide a first-time demonstration of long-term, in situ and combined measurements of photosynthetic gas-exchange and ChlF. We do so by integrating a new miniature pulse amplitude modulated-fluorometer into an existing system of automated chambers to track photosynthetic gas-exchange of leaves and shoots in situ. The setup is used to track the dynamics of the light and carbon reactions of photosynthesis at a 20-min resolution in leaves of silver birch (Betula pendula Roth) during summertime. The potential of the method is illustrated using the ratio between electron transport and net assimilation (ETR/ANET), which reflects the internal electron use efficiency of photosynthesis. The setup successfully captured the diurnal patterns in the ETR/ANET during summertime, including a large increase in noon ETR/ANET in response to a period of high temperatures and relatively low soil moisture, pointing to a drastic decrease in electron-use efficiency. The observations emphasize the value of combined and long-term in situ measurements of ChlF and gas-exchange, opening new opportunities to investigate, model and quantify the regulation of photosynthesis in situ and the connection between ChlF and photosynthetic gas-exchange. The next steps, potential and limitations of the approach are discussed. [ABSTRACT FROM AUTHOR]

Phenols play a crucial role as core structural motifs in natural products and also serve as fundamental building blocks in synthetic chemistry. Apart from the known protocols for the conversion of aryl precursors to phenols (i. e., decarboxylative oxygenation), we report here the efficient synthesis of phenols from the stable and readily available benzylic carboxylic acids under mild reaction conditions. The photocatalytic conversion of carboxylic acids to peroxides is a crucial step in this strategy, allowing the subsequent C−O bond formation via Hock rearrangement. [ABSTRACT FROM AUTHOR]

[Display omitted] Secular changes in atmospheric CO 2 and consequent global climate variations, are commonly attributed to global outgassing and the efficiency of silicate weathering, which may have been linked to mountain formation, land/arc distribution, and plant colonization through geological time. Although oxidative weathering has been shown to exert a significant role in the propagation of weathering fronts through the oxidation of Fe-bearing minerals, the influence of atmospheric O 2 concentration (p O 2) on silicate weathering, CO 2 consumption, and global climate has not been thoroughly evaluated. This study presents a numerical model aimed at estimating the effects of p O 2 on the climate, considering the influence of p O 2 on the regolith thickness and thus weathering duration of granitic domains. Our model simulations reveal that an increase in weathering efficiency, through deeper penetration of the oxidative weathering front in the granitic regolith, would independently introduce a steady-state climate cooling of up to ∼8 °C, in step with one-order of magnitude rise in p O 2. This temperature change may have repeatedly initiated the runaway ice-albedo feedback, leading to global glacial events (e.g., Neoproterozoic Snowball Earth). Increasing granitic weathering efficiency caused by a substantial p O 2 increase may also have contributed to the development of icehouse climate during the Phanerozoic. [ABSTRACT FROM AUTHOR]

After systematic realization of decarboxylative functionalization of carboxylic acids under heating conditions in our group, we herein reported an electrochemical method for Ni‐catalyzed decarboxylative oxygenation of arylacetic acids under open air conditions. The protocol provided corresponding carbonyls including aldehydes and ketones in moderate to satisfactory yields with good functional group tolerance, furthermore, the practicability and advantage of the method was highlighted through Ni‐catalyzed oxidative decarboxylation of carboxylic acid‐containing drugs and preformation of scalable transformation. Mechanistic studies demonstrated that the possible involvement of free radical intermediate in the conversion. [ABSTRACT FROM AUTHOR]

The early Paleoproterozoic (ca. 2.5–2.2 Ga) represents a critical juncture in Earth history, marking the inception of an oxygenated atmosphere while bearing witness to potentially multiple widespread and severe glaciations. Deciphering the nature of this glacial epoch and its connection with atmospheric oxygenation has, however, proven difficult, hindered by a reliance on disputed stratigraphic correlations given the paucity of direct radiometric age constraints. Nowhere is this more acute than within the South African Transvaal Supergroup: Here, while the loss of oxygen-sensitive mass-independent sulfur isotope fractionation (S-MIF) has been reported from both the Duitschland and Rooihoogte formations, divided opinion surrounding the time-equivalence of these units has prompted authors to argue for vastly different oxygenation trajectories. Addressing this debate, we present a depositional Re-Os age (2443 ± 33 Ma) from diamictite samples preserved in drillcore of the upper Duitschland Formation. The 100-million-year separation between the Duitschland Formation and its previously presumed equivalent reveals at least two isolated disappearances of S-MIF, requiring that the Great Oxidation Event was dynamic and proceeded via discrete oxygenation episodes whose structure remains incompletely understood. Importantly, our revised framework aligns the lower Duitschland diamictite with the low-latitude glacigenic Makganyene Formation, supporting hypotheses of widespread regional, and potentially global, early Paleoproterozoic glaciation. [ABSTRACT FROM AUTHOR]

Volatile Organic Compounds (VOCs) are not only essential precursors for the formation of ozone and PM2.5, but also hazardous to human health and responsible for unpleasant odors. The pharmaceutical industry has become an important industrial source of VOCs due to China's large emissions and complex emission chains. In total, 245 VOCs samples were collected and analyzed from 11 typical pharmaceutical companies in Zibo City of the North China Plain, in order to investigate the VOCs emission characteristics and odor impacts. The emission factor for the pharmaceutical industry was 7.97 ± 8.21 g/kg pharmaceuticals, while the main emission links were chimney emissions, equipment sealing leakage, and so on. Finally, considering both purifying efficiency and economic benefits, the multistage absorption (AB) method is most effective for VOCs concentrations below 100 mg/m3, while UV photo-oxygenation combined with adsorption (UVA) is more suitable for concentrations below 300 mg/m3. The Regenerative Thermal Oxidizer (RTO), Catalytic Oxidizer (CO), and Condensation + Adsorption (CA) technologies demonstrated greater stability and efficiency, particularly in the treatment of complex organic pollutants, highlighting their advantages in both VOCs and odor removal at higher concentrations. [ABSTRACT FROM AUTHOR]

Iodine (I) abundance in marine carbonates (measured as an elemental ratio with calcium, I / Ca) is of broad interest as a proxy for local/regional ocean redox. This connection arises because the speciation of iodine in seawater, the balance between iodate (IO 3-) and iodide (I−), is sensitive to the prevalence of oxic vs. anoxic conditions. However, although I / Ca ratios are increasingly commonly being measured in ancient carbonate samples, a fully quantitative interpretation of this proxy requires the availability of a mechanistic interpretative framework for the marine iodine cycle that can account for the extent and intensity of ocean deoxygenation in the past. Here we present and evaluate a representation of marine iodine cycling embedded in an Earth system model ("cGENIE") against both modern and paleo-observations. In this framework, we account for IO 3- uptake and release of I− through the biological pump, the reduction in ambient IO 3- to I− in the water column, and the re-oxidation of I− to IO 3-. We develop and test a variety of different plausible mechanisms for iodine reduction and oxidation transformation and contrast model projections against an updated compilation of observed dissolved IO 3- and I− concentrations in the present-day ocean. By optimizing the parameters controlling previously proposed mechanisms involved in marine iodine cycling, we find that we can obtain broad matches to observed iodine speciation gradients in zonal surface distribution, depth profiles, and oxygen-deficient zones (ODZs). However, we also identify alternative, equally well performing mechanisms which assume a more explicit mechanistic link between iodine transformation and environment – an ambiguity that highlights the need for more process-based studies on modern marine iodine cycling. Finally, to help distinguish between competing representations of the marine iodine cycle and because our ultimate motivation is to further our ability to reconstruct ocean oxygenation in the geological past, we conducted "plausibility tests" of different model schemes against available I / Ca measurements made on Cretaceous carbonates – a time of substantially depleted ocean oxygen availability compared to modern and hence a strong test of our model. Overall, the simultaneous broad match we can achieve between modeled iodine speciation and modern observations, and between forward proxy modeled I / Ca and geological elemental ratios, supports the application of our Earth system modeling in simulating the marine iodine cycle to help interpret and constrain the redox evolution of past oceans. [ABSTRACT FROM AUTHOR]

Rhenium (Re) and uranium (U) are essential proxies in reconstructing past oceanic oxygenation evolution. However, their removal in continental shelf sediments, hotspots of early diagenesis, were previously treated as quantitatively unimportant sinks in the ocean. Here we examine the sedimentary reductive removal of Re and U and their coupling with organic carbon decomposition, utilizing the 224Ra/228Th disequilibria within the East China Sea shelf. We identified positive correlations between their removal fluxes and the rates of sediment oxygen consumption or organic carbon decomposition. These correlations enable an evaluation of global shelf reductive sinks that are comparable to (for Re) or higher than (~4-fold for U) previously established suboxic/anoxic sinks. These findings suggest potential imbalances in the modern budgets of Re and U, or perhaps a substantial underestimation of their sources. Our study thus highlights shelf sedimentary reductive removal as critical yet overlooked sinks for Re and U in the modern ocean. The sources and sinks of Re and U in the modern ocean may be imbalanced, according to sedimentary porewater analysis and assessment of reductive Re and U removal on the continental shelf [ABSTRACT FROM AUTHOR]

Molybdoenzymes are essential in global nitrogen, carbon, and sulfur cycling. To date, the only known bioavailable source of molybdenum (Mo) is molybdate. However, in the sulfidic and anoxic (euxinic) habitats that predominate in modern subsurface environments and that were pervasive prior to Earth's widespread oxygenation, Mo occurs as soluble tetrathiomolybdate ion and molybdenite mineral that is not known to be bioavailable. This presents a paradox for how organisms obtain Mo to support molybdoenzymes in these environments. Here, we show that tetrathiomolybdate and molybdenite sustain the high Mo demand of a model anaerobic methanogen, Methanococcus maripaludis, grown via Mo-dependent formate dehydrogenase, formylmethanofuran dehydrogenase, and nitrogenase. Cells grown with tetrathiomolybdate and molybdenite have similar growth kinetics, Mo content, and transcript levels of proteins involved in Mo transport and cofactor biosynthesis when compared to those grown with molybdate, implying similar mechanisms of transport and cofactor biosynthesis. These results help to reconcile the paradox of how Mo is acquired in modern and ancient anaerobes and provide new insight into how molybdoenzymes could have evolved prior to Earth's oxygenation. The nitrogen-fixing anaerobic methanogen, Methanococcus maripaludis, can utilize tetrathiomolybdate and molybdenite, previously considered non-bioavailable, as sources of molybdenum for enzymes involved in nitrogen fixation and anaerobic metabolism. [ABSTRACT FROM AUTHOR]

Unspecific Peroxygenases (UPOs) have emerged as robust biocatalysts for selective oxygenation reactions, as they are easily produced at scale and require only hydrogen peroxide as the external oxidant. UPOs can catalyze the oxygenation of the primary benzylic carbons of toluenes to give alcohol, aldehyde and carboxylic acid products. They can also catalyze hydroxylation at the benzylic position of ethylbenzenes, and the subsequent oxidation of the secondary alcohols to ketones. In this study, we have investigated factors that affect the balance of products in UPO‐catalyzed benzylic oxygenations using a range of functionalised toluenes and ethyl benzenes, and a UPO from Agrocybe aegerita (rAaeUPO‐PaDa‐I‐H variant). The product distribution is dependent upon a mixture of steric and electronic effects and, in selected cases, controlling the reaction conditions permits products from each product series to be generated chemoselectively. In this way, electron poor toluenes were converted directly into carboxylic acids in isolated yields of 36–99 % on preparative scale. [ABSTRACT FROM AUTHOR]

Strategic design for the construction of contiguous tetrasubstituted carbon centers represents a daunting challenge in synthetic organic chemistry. Herein, we report a combined experimental and computational investigation aimed at developing catalytic aerobic carbooxygenation, involving the intramolecular addition of tertiary radicals to geminally disubstituted alkenes, followed by aerobic oxygenation. This reaction provides a straightforward route to various α,α,β,β‐tetrasubstituted γ‐lactones, which can be readily transformed into hexasubstituted γ‐lactones through allylation/translactonization. Computational analysis reveals that the key mechanistic foundation for achieving the developed aerobic carbooxygenation involves the design of endothermic (energetically uphill) C−C bond formation followed by exothermic (energetically downhill) oxygenation. Furthermore, we highlight a unique fluorine‐induced stereoelectronic effect that stabilizes the endothermic stereodetermining transition state. [ABSTRACT FROM AUTHOR]

Demonstrated here is an external photo‐sensitizer‐free (auto‐sensitized) singlet oxygen‐enabled solvent‐dependent tertiary hydroxylation and aryl‐alkyl spiro‐etherification of C3‐maleimidated quinoxalines. Such "reagent‐less" photo‐oxygenation at Csp3‐H and etherification involving Csp3‐H/Csp2‐H are unparalleled. Possibly, the highly π‐conjugated N‐H tautomer allows the substrate to get excited by irradiation, and subsequently, it attains the triplet state via ISC. This excited triplet‐state sensitized molecule then transfers its energy to a triplet‐state oxygen (3O2) generating reactive singlet oxygen (1O2) for hydroxylation and spirocyclization depending on the solvent used. In HFIP, the generated alkoxy radical accepts a proton via HAT giving hydroxylated product. In contrast, in an aprotic PhCl it underwent a radical addition at the ortho‐position of the C2 aryl to provide spiro‐ether. An unprecedented orthogonal spiro‐etherification was observed via the displacement of o‐substitutents for ortho (−OEt, −OMe, −F, −Cl, −Br) substituted substrates. The order of ipso substitution follows the trend −OMe>−OEt>−F>−H>−Cl>−Br. Both these oxygenation reactions can be carried out with nearly equal ease using direct sunlight without the requirement of any elaborate reaction setup. Demonstration of large‐scale synthesis and a few interesting transformations have also been realized. Furthermore, several insightful control experiments and quantum chemical computations were performed to unravel the mechanism. [ABSTRACT FROM AUTHOR]

Atmospheric oxygen levels are traditionally viewed to have been relatively stable throughout Earth's history with several-step increases. Emerging evidence, however, suggests extremely dynamic atmospheric oxygen levels through large swaths of Earth's history. Here, we provide a new perspective on atmospheric oxygen evolution using a dynamical analysis to explore the relative importance of previously proposed feedbacks on the global oxygen and carbon cycles. Our results from a stochastic analysis of oxygen mass balance in this framework suggest there are multiple steady states for atmospheric oxygen, but only three stable states. One stable state under anoxic conditions (<10−5 present atmospheric level (PAL)), one at low (~10−3to 10−2 PAL), and one near modern value atmospheric oxygen levels. Our findings also suggest two unstable states (tipping points) for atmospheric oxygen: one around 10−5 and another one around 10−1 PAL. Atmospheric oxygen levels tend to be stable under anoxic, low oxygen, and near-modern conditions, with two unstable states at around 10−5 and 10−1 present atmospheric level, according to the results from a stochastic analysis of oxygen mass balance. [ABSTRACT FROM AUTHOR]

The decarboxylative oxygenation of readily available carboxylic acids as well as the oxidation of alkenes and alkanes has been accomplished through visible light using g‐C3N4 as a robust and recyclable catalyst. The scalable protocol furnishes an array of aldehydes and ketones under mild reaction conditions, requiring only molecular oxygen as an oxidant. Notably, no addition of stochiometric amounts of base is required, and furthermore, the reaction proceeds efficiently open to the air. [ABSTRACT FROM AUTHOR]

We report an iron‐catalyzed decarboxylative C(sp3)−O bond‐forming reaction under mild, base‐free conditions with visible light irradiation. The transformation uses readily available and structurally diverse carboxylic acids, iron photocatalyst, and 2,2,6,6‐tetramethylpiperidine 1‐oxyl (TEMPO) derivatives as oxygenation reagents. The process exhibits a broad scope in acids possessing a wide range of stereoelectronic properties and functional groups. The developed reaction was applied to late‐stage oxygenation of a series of bio‐active molecules. The reaction leverages the ability of iron complexes to generate carbon‐centered radicals directly from carboxylic acids by photoinduced carboxylate‐to‐iron charge transfer. Kinetic, electrochemical, EPR, UV/Vis, HRMS, and DFT studies revealed that TEMPO has a triple role in the reaction: as an oxygenation reagent, an oxidant to turn over the Fe‐catalyst, and an internal base for the carboxylic acid deprotonation. The obtained TEMPO adducts represent versatile synthetic intermediates that were further engaged in C−C and C‐heteroatom bond‐forming reactions using commercial organo‐photocatalysts and nucleophilic reagents. [ABSTRACT FROM AUTHOR]

An increase in atmospheric p O2 has been proposed as a trigger for the Cambrian Explosion at ∼539–514 Ma but the mechanistic linkage remains unclear. To gain insights into marine habitability for the Cambrian Explosion, we analysed excess Ba contents (Baexcess) and isotope compositions (δ138Baexcess) of ∼521-Myr-old metalliferous black shales in South China. The δ138Baexcess values vary within a large range and show a negative logarithmic correlation with Baexcess, suggesting a major (>99%) drawdown of oceanic Ba inventory via barite precipitation. Spatial variations in Baexcess and δ138Baexcess indicate that Ba removal was driven by sulfate availability that was ultimately derived from the upwelling of deep seawaters. Global oceanic oxygenation across the Ediacaran–Cambrian transition may have increased the sulfate reservoir via oxidation of sulfide and concurrently decreased the Ba reservoir by barite precipitation. The removal of both H2S and Ba that are deleterious to animals could have improved marine habitability for early animals. [ABSTRACT FROM AUTHOR]

Electrocatalytic oxygenation of hydrocarbons with high selectivity has attracted much attention for its advantages in the sustainable and controllable production of oxygenated compounds with reduced greenhouse gas emissions. Especially when utilizing water as an oxygen source, by constructing a water-to-oxygenates conversion system at the anode, the environment and/or energy costs of producing oxygenated compounds and hydrogen energy can be significantly reduced. There is a broad consensus that the generation and transformation of oxygen species are among the decisive factors determining the overall efficiency of oxygenation reactions. Thus, it is necessary to elucidate the oxygen transfer process to suggest more efficient strategies for electrocatalytic oxygenation. Herein, we introduce oxygen transfer routes through redox-mediated pathways or direct oxygen transfer methods. Especially for the scarcely investigated direct oxygen transfer at the anode, we aim to detail the strategies of catalyst design targeting the efficient oxygen transfer process including activation of organic substrate, generation/adsorption of oxygen species, and transformation of oxygen species for oxygenated compounds. Based on these examples, the significance of balancing the generation and transformation of oxygen species, tuning the states of organic substrates and intermediates, and accelerating electron transfer for organic activation for direct oxygen transfer has been elucidated. Moreover, greener organic synthesis routes through heteroatom transfer and molecular fragment transfer are anticipated beyond oxygen transfer. [ABSTRACT FROM AUTHOR]

Aberrant aggregates of amyloid‐β (Aβ) and tau protein (tau), called amyloid, are related to the etiology of Alzheimer disease (AD). Reducing amyloid levels in AD patients is a potentially effective approach to the treatment of AD. The selective degradation of amyloids via small molecule‐catalyzed photooxygenation in vivo is a leading approach; however, moderate catalyst activity and the side effects of scalp injury are problematic in prior studies using AD model mice. Here, leuco ethyl violet (LEV) is identified as a highly active, amyloid‐selective, and blood‐brain barrier (BBB)‐permeable photooxygenation catalyst that circumvents all of these problems. LEV is a redox‐sensitive, self‐activating prodrug catalyst; self‐oxidation of LEV through a hydrogen atom transfer process under photoirradiation produces catalytically active ethyl violet (EV) in the presence of amyloid. LEV effectively oxygenates human Aβ and tau, suggesting the feasibility for applications in humans. Furthermore, a concept of using a hydrogen atom as a caging group of a reactive catalyst functional in vivo is postulated. The minimal size of the hydrogen caging group is especially useful for catalyst delivery to the brain through BBB. [ABSTRACT FROM AUTHOR]

Repurposing enzymes to catalyze non‐natural asymmetric transformations that are difficult to achieve using traditional chemical methods is of significant importance. Although radical C−O bond formation has emerged as a powerful approach for constructing oxygen‐containing compounds, controlling the stereochemistry poses a great challenge. Here we present the development of a dual bio‐/photo‐catalytic system comprising an ene‐reductase and an organic dye for achieving stereoselective lactonizations. By integrating directed evolution and photoinduced single electron oxidation, we repurposed engineered ene‐reductases to steer non‐natural radical C−O formations (one C−O bond for hydrolactonizations and lactonization‐alkylations while two C−O bonds for lactonization‐oxygenations). This dual catalysis gave a new approach to a diverse array of enantioenhanced 5‐ and 6‐membered lactones with vicinal stereocenters, part of which bears a quaternary stereocenter (up to 99 % enantiomeric excess, up to 12.9 : 1 diastereomeric ratio). Detailed mechanistic studies, including computational simulations, uncovered the synergistic effect of the enzyme and the externally added organophotoredox catalyst Rh6G. [ABSTRACT FROM AUTHOR]

Two 3-(p-substituted phenyl)-3a,8a-dihydro-4H-cyclohepta[d]isoxazoles were synthesized by 1,3-dipolar cycloaddition of the corresponding nitrile oxides with cycloheptatriene. Two endoperoxides were synthesized as facially selective and single products in high yields (93%--95%) from the reactions of isoxazole derivatives with singlet oxygen. The exact configurations of the endoperoxide with a methyl group in the phenyl ring and the diol synthesized from it were confirmed by X-ray analysis. To elucidate the mechanism, the formation energy of the endoperoxide was investigated by simulations using the software package Gaussian 09 and density functional theory calculations via the M06-2X/6-311+G(d,p) level method in dichloromethane. The results were consistent with experimental findings showing the formation of isoxazole products. [ABSTRACT FROM AUTHOR]

The control of a molecule's geometry, chirality, and physical properties has long been a challenging pursuit. Our study introduces a dependable method for assembling D3-symmetric trigonal bipyramidal coordination cages. Specifically, D2h-symmetric anions, like oxalate and chloranilic anions, self-organize around a metal ion to form chiral-at-metal anionic complexes, which template the formation of D3-symmetric trigonal bipyramidal coordination cages. The chirality of the trigonal bipyramid is determined by the point chirality of chiral amines used in forming the ligands. Additionally, these cages exhibit chiral selectivity for the included chiral-at-metal anionic template. Our method is broadly applicable to various ligand systems, enabling the construction of larger cages when larger D2h-symmetric anions, like chloranilic anions, are employed. Furthermore, we successfully produce enantiopure trigonal bipyramidal cages with anthracene-containing backbones using this approach, which would be otherwise infeasible. These cages exhibit circularly polarized luminescence, which is modulable through the reversible photo-oxygenation of the anthracenes. The control of a molecule's geometry, chirality, and physical properties has long been a challenging pursuit. Here the authors introduce a method for assembling D3-symmetric trigonal bipyramidal coordination cages which exhibit chiral selectivity for the included chiral-at-metal anionic template. [ABSTRACT FROM AUTHOR]

Lower Pliensbachian hemipelagic successions from the northern Iberian palaeomargin are characterized by the occurrence of organic-rich calcareous rhythmites of decimetre-thick limestone and marl beds as well as thicker black shale intervals. Understanding the genetic mechanisms of the cyclic lithologies and processes involved along with the nature of the carbon cycle is of primary interest. This cyclostratigraphic study, carried out in one of the black shale intervals exposed in Santiurde de Reinosa (Basque–Cantabrian Basin), reveals that the calcareous rhythmites responded to periodic environmental variations in the Milankovitch-cycle band and were likely driven by eccentricity-modulated precession. The main environmental processes that determined the formation of the rhythmite were deduced on the basis of the integrated sedimentological, mineralogical, and geochemical study of an eccentricity bundle. The formation of precession couplets was controlled by variations in carbonate production and dilution by terrigenous supplies, along with periodic changes in bottom-water oxygenation. Precessional configurations with marked annual seasonality increased terrigenous input (by rivers or wind) to marine areas and boosted organic productivity in surface water. The great accumulation of organic matter on the seabed eventually decreased bottom-water oxygenation, which might also be influenced by reduced ocean ventilation. Thus, deposition of organic-rich marls and shales occurred when annual seasonality was maximal. On the contrary, a reduction in terrestrial inputs at precessional configurations with minimal seasonality diminished shallow organic productivity, which, added to an intensification of vertical mixing, contributed to increasing the oxidation of organic matter. These conditions also favoured greater production and basinward export of carbonate mud in shallow marine areas, causing the formation of limy hemipelagic beds. Short eccentricity cycles modulated the amplitude of precession-driven variations in terrigenous input and oxygenation of bottom seawater. Thus, the amplitude of the contrast between successive precessional beds increased when the Earth's orbit was elliptical and diminished when it was circular. The data also suggest that short eccentricity cycles affected short-term sea level changes, probably through orbitally modulated aquifer eustasy. [ABSTRACT FROM AUTHOR]

Rieske non-heme iron oxygenases (ROs) are redox enzymes essential for microbial biodegradation and natural product synthesis. These enzymes utilize molecular oxygen for oxygenation reactions, making them very useful biocatalysts due to their broad reaction scope and high selectivities. The mechanism of oxygen activation in ROs involves electron transfers between redox centers of associated protein components, forming an electron transfer chain (ETC). Although the ETC is essential for electron replenishment, it carries the risk of reactive oxygen species (ROS) formation due to electron loss during oxygen activation. Our previous study linked ROS formation to O 2 uncoupling in the flavin-dependent reductase of the three-component cumene dioxygenase (CDO). In the present study, we extend this finding by investigating the effects of ROS formation on the multi-component CDO system in a cell-free environment. In particular, we focus on the effects of hydrogen peroxide (H 2 O 2) formation in the presence of a NADH cofactor regeneration system on the catalytic efficiency of CDO in vitro. Based on this, we propose the implementation of hybrid systems with alternative (non-native) redox partners for CDO, which are highly advantageous in terms of reduced H 2 O 2 formation and increased product formation. The hybrid system consisting of the RO-reductase from phthalate dioxygenase (PDR) and CDO proved to be the most promising for the oxyfunctionalization of indene, showing a 4-fold increase in product formation (20 mM) over 24 h (TTN of 1515) at a 3-fold increase in production rate. • In vitro , reactive oxygen species are linked to O 2 uncoupling at the reductase of a three-component Rieske oxygenase. • H 2 O 2 formation has a strong effect on the catalytic efficiency of Cumene dioxygenase in cell-free reactions. • An NADH cofactor regeneration system induces H 2 O 2 generation due to O 2 uncoupling. • Using alternative reductases in hybrid systems reduces H 2 O 2 formation and improves catalytic efficiency of CDO in vitro. [ABSTRACT FROM AUTHOR]

Here we report an aerobic photoredox catalysis approach to oxamate ester synthesis using bromodifluoroacetate esters and amines under open‐air conditions. Oxamate ester is an important skeleton found in bioactive molecules and used as a synthetic building block. However, previous synthetic methods require the use of moisture‐ and air‐sensitive precursors and/or harsh conditions, limiting accessible oxamate esters. The present method uses bench‐stable bromodifluoroacetate esters and amines under mild photoredox catalytic conditions to furnish a wide variety of oxamate esters. Combining photoredox catalysis with aerobic oxygenation enables the use of bromodifluoroacetate ester as a precursor for the synthesis of oxamate esters via fluoroglyoxylate esters. [ABSTRACT FROM AUTHOR]

Background: The oxygenation index (OI) and oxygen saturation index (OSI) are proven mortality predictors in pediatric and adult patients, traditionally using mean airway pressure (Pmean). We introduce novel indices, replacing Pmean with DP (ΔPinsp), MPdyn, and MPtot, assessing their potential for predicting COVID-19 acute respiratory distress syndrome (ARDS) mortality, comparing them to traditional indices. Methods: We studied 361 adult COVID-19 ARDS patients for 7 days, collecting ΔPinsp, MPdyn, and MPtot, OI-ΔPinsp, OI-MPdyn, OI-MPtot, OSI-ΔPinsp, OSI-MPdyn, and OSI-MPtot. We compared these in surviving and non-surviving patients over the first 7 intensive care unit (ICU) days using Mann–Whitney U test. Logistic regression receiver operating characteristic (ROC) analysis assessed AUC and CI values for ICU mortality on day three. We determined cut-off values using Youden's method and conducted multivariate Cox regression on parameter limits. Results: All indices showed significant differences between surviving and non-surviving patients on the third day of ICU care. The AUC values of OI-ΔPinsp were significantly higher than those of P/F and OI-Pmean (P values.0002 and <.0001, respectively). Similarly, AUC and CI values of OSI-ΔPinsp and OSI-MPdyn were significantly higher than those of SpO2/FiO2 and OSI-Pmean values (OSI-ΔPinsp: P <.0001, OSI-MPdyn: P values.047 and.028, respectively). OI-ΔPinsp, OSI-ΔPinsp, OI-MPdyn, OSI-MPdyn, OI-MPtot, and OSI-MPtot had AUC values of 0.72, 0.71, 0.69, 0.68, 0.66, and 0.64, respectively, with cut-off values associated with hazard ratios and P values of 7.06 (HR = 1.84, P =.002), 8.04 (HR = 2.00, P ≤.0001), 7.12 (HR = 1.68, P =.001), 5.76 (HR = 1.70, P ≤.0001), 10.43 (HR = 1.52, P =.006), and 10.68 (HR = 1.66, P =.001), respectively. Conclusions: Critical values of all indices were associated to higher ICU mortality rates and extended mechanical ventilation durations. The OI-ΔPinsp, OSI-ΔPinsp, and OSI-MPdyn indices displayed the strongest predictive capabilities for ICU mortality. These novel indices offer valuable insights for intensivists in the clinical management and decision-making process for ARDS patients. [ABSTRACT FROM AUTHOR]

The oxygenation of Earth's atmosphere represents the quintessential transformation of a planetary surface by microbial processes. In turn, atmospheric oxygenation transformed metabolic evolution; molecular clock models indicate the diversification and ecological expansion of respiratory metabolisms in the several hundred million years following atmospheric oxygenation. Across this same interval, the geological record preserves 13C enrichment in some carbonate rocks, called the Lomagundi-Jatuli excursion (LJE). By combining data from geologic and genomic records, a self-consistent metabolic evolution model emerges for the LJE. First, fermentation and methanogenesis were major processes remineralizing organic carbon before atmospheric oxygenation. Once an ozone layer formed, shallow water and exposed environments were shielded from UVB/C radiation, allowing the expansion of cyanobacterial primary productivity. High primary productivity and methanogenesis led to preferential removal of 12C into organic carbon and CH4. Extreme and variable 13C enrichments in carbonates were caused by 13C-depleted CH4 loss to the atmosphere. Through time, aerobic respiration diversified and became ecologically widespread, as did other new metabolisms. Respiration displaced fermentation and methanogenesis as the dominant organic matter remineralization processes. As CH4 loss slowed, dissolved inorganic carbon in shallow environments was no longer highly 13C enriched. Thus, the loss of extreme 13C enrichments in carbonates marks the establishment of a new microbial mat ecosystem structure, one dominated by respiratory processes distributed along steep redox gradients. These gradients allowed the exchange of metabolic by-products among metabolically diverse organisms, providing novel metabolic opportunities. Thus, the microbially induced oxygenation of Earth's atmosphere led to the transformation of microbial ecosystems, an archetypal example of planetary microbiology. [ABSTRACT FROM AUTHOR]

Plasmonic nanocomposites ZnO–Ag and ZnO–SnO2–Ag(AgCl) were prepared by the polymer–salt method, and their structure and morphology were studied using XRD and SEM analyses. It was found that the addition of photoactive inorganic nanocomposites ZnO–Ag and ZnO–SnO2–Ag(AgCl) in pure water significantly enhances the effectiveness of its disinfection and purification during UV treatment and provides the effective water oxygenation. Oxygen photogeneration under blue light (λex. = 405 nm) can be related to the plasmon-excitation processes in ZnO–SnO2–Ag(AgCl) composites. Prepared composites demonstrate antibacterial activity against both Gram-positive and Gram-negative bacteria. The increase of Ag content in ZnO–Ag and ZnO–SnO2–Ag(AgCl) composites significantly enhances their antibacterial activity. [ABSTRACT FROM AUTHOR]

This article discusses the potential use of rose bengal as a catalyst for the oxygenation of amyloid-beta (Aβ) in the treatment of Alzheimer's disease (AD). AD is a neurodegenerative disease characterized by the presence of Aβ aggregates in the brain. The article explores the limitations of traditional photooxygenation strategies and proposes the use of ultrasound as an alternative energy source to activate the catalyst. The authors conducted experiments to optimize the ultrasound irradiation conditions and found that rose bengal exhibited the highest sonooxygenating activity on Aβ. Further research is needed to fully understand the mechanism and potential of this approach for AD treatment. [Extracted from the article]

(1) Background: Oxygen has exerted a great effect in shaping the environment and driving biological diversity in Earth's history. Green lineage has evolved primary and secondary carotenoid biosynthetic systems to adapt to Earth's oxygenation, e.g., Haematococcus lacustris, which accumulates the highest amount of secondary astaxanthin under stresses. The two systems are controlled by lycopene ε-cyclase (LCYE) and β-cyclase (LCYB), which leave an important trace in Earth's oxygenation. (2) Objectives: This work intends to disclose the underlying molecular evolutionary mechanism of Earth's oxygenation in shaping green algal carotenogensis with a special focus on lycopene cyclases. (3) Methods: The two kinds of cyclases were analyzed by site-directed mutagenesis, phylogeny, divergence time and functional divergence. (4) Results: Green lineage LCYEs appeared at ~1.5 Ga after the first significant appearance and accumulation of atmospheric oxygen, the so-called Great Oxygenation Event (GOE), from which LCYBs diverged by gene duplication. Bacterial β-bicyclases evolved from β-monocyclase. Enhanced catalytic activity accompanied evolutionary transformation from ε-/β-monocyclase to β-bicyclase. Strong positive selection occurred in green lineage LCYEs after the GOE and in algal LCYBs during the second oxidation, the Neoproterozoic Oxygenation Event (NOE). Positively selected sites in the catalytic cavities of the enzymes controlled the mono-/bicyclase activity, respectively. Carotenoid profiling revealed that oxidative adaptation has been wildly preserved in evolution. (5) Conclusions: the functionalization of the two enzymes is a result of primary to secondary adaptations to Earth's oxygenation. [ABSTRACT FROM AUTHOR]

The catalytically active center of the enzyme tyrosinase, standing out for its unusual substrate diversity, consists of a side‐on μ‐η2:η2‐peroxido complex (SP). Several ligand systems stabilizing a SP and able to mimic the catalytic activity of the enzyme towards simple phenolic substrates are known. Only a few catalytically active systems based on the isoelectronic isomer structure of SP, a bis(μ‐oxido)dicopper(III) complex (O), were investigated until now. Two years ago, we presented with the TMGbenza a hybrid guanidine based tyrosinase model system stabilizing an O species with an exceptional substrate diversity. Herein we studied the catalytic activity of another O species stabilized by the bisguanidine ligand TMG2tol. The reaction conditions for the catalytic oxygenation were optimized and a broad spectrum of phenolic substrates like naphthol, quinolinols and indolols was tested. Naturally occurring phenazine derivatives like phenazine‐1‐carboxylamide (PCN) and phenazine‐1‐carboxylic acid (PCA) show antifungal as well as antibacterial activity, functioning as biological control agents against crop disease like take‐all. Hence, the synthesized phenazines were evaluated for their potential antimicrobial activities against representative gram‐positive and gram‐negative bacteria. [ABSTRACT FROM AUTHOR]

Understanding the oceanic phosphate concentration is critical for understanding marine productivity and oxygen evolution throughout Earth history. During the Archean, estimates of marine phosphate levels range from scarce to enriched conditions. However, biogeochemical conditions required for sustaining high phosphate concentrations while retaining an anoxic atmosphere during the Archean remain ambiguous. Here, we employ a biogeochemical model of the marine phosphate cycle to determine the conditions under which oceanic phosphate levels could have been higher than present‐day values during the Archean after the emergence of oxygenic photoautotrophs (OP). We show that, under the presence of OP, phosphate‐rich oceans require the limitation by factors other than phosphate, or a high outgassing rate of reducing gases. If these conditions were not met, the occurrence of oceanic phosphate levels higher than present‐day values during the Archean would require the absence of OP. Plain Language Summary: The availability of phosphorus, a limiting nutrient in the ocean, is critical for understanding marine productivity in the history of the Earth, and hence atmospheric oxygen levels. On early Earth, the atmospheric oxygen level was much lower than the present conditions, and marine phosphate concentrations have been lower than the present level. However, an emerging proxy of the past phosphate level indicates a phosphate‐enriched condition, which may contradict low atmospheric oxygen levels. To reveal the conditions required for sustaining high phosphate concentrations while retaining an anoxic atmosphere, we employed a theoretical model of the marine phosphate cycle. We show that, if oxygenic photosynthesis has evolved on early Earth, the primary productivity needs to be limited by factors other than phosphorus, such as nitrogen, or a high outgassing rate of reducing gases from volcanoes would be required for achieving high marine phosphate concentrations. If these conditions were not met, phosphate‐rich conditions on early Earth would be limited to the periods before the evolution of oxygenic photosynthesis. Key Points: The marine phosphate levels on early Earth after the evolution of oxygenic photosynthesis are estimated using a theoretical modelPhosphate‐rich oceans cause atmospheric oxygenation under reasonable outgassing rates of reducing gasesWithout suitable conditions, absence of oxygenic photosynthesis would be required for the phosphate‐rich oceans during the Archean [ABSTRACT FROM AUTHOR]

Molecular innovations within key metabolisms can have profound impacts on element cycling and ecological distribution. Yet, much of the molecular foundations of early evolved enzymes and metabolisms are unknown. Here, we bring one such mystery to relief by probing the birth and evolution of the G-subunit protein, an integral component of certain members of the nitrogenase family, the only enzymes capable of biological nitrogen fixation. The G-subunit is a Paleoproterozoic-age orphan protein that appears more than 1 billion years after the origin of nitrogenases. We show that the G-subunit arose with novel nitrogenase metal dependence and the ecological expansion of nitrogen-fixing microbes following the transition in environmental metal availabilities and atmospheric oxygenation that began ∼2.5 billion years ago. We identify molecular features that suggest early G-subunit proteins mediated cofactor or protein interactions required for novel metal dependency, priming ancient nitrogenases and their hosts to exploit these newly diversified geochemical environments. We further examined the degree of functional specialization in G-subunit evolution with extant and ancestral homologs using laboratory reconstruction experiments. Our results indicate that permanent recruitment of the orphan protein depended on the prior establishment of conserved molecular features and showcase how contingent evolutionary novelties might shape ecologically important microbial innovations. [ABSTRACT FROM AUTHOR]

We present Earth's Oxygenation and Natural Systematics (EONS): a new, fully coupled biogeochemical model of the atmosphere, ocean, and their interactions with the geosphere, which can reproduce major features of Earth's evolution following the origin of life to the present day. The model, consisting of 257 unique fluxes between 96 unique chemical reservoirs, includes an interactive biosphere, cycles of carbon, nitrogen, phosphorus, and oxygen, and climate. A nominal model run initialized in the Eoarchean resolves emergent surface oxygenation, nutrient limitations, and climate feedbacks. The modeled atmosphere oxygenates in stepwise fashion over the course of the Proterozoic; a nearly billion year lag after the evolution of photosynthesis at 3.5 Ga is followed by a great oxidation event at 2.4 Ga, which appears to be caused by the gradual buildup of organic matter on the continents imposing nutrient limitation on the biosphere by removing key nutrients from the ocean system. The simple climate system shows significant temperature shifts punctuate the oxygenation process, implying that major biological transitions possibly destabilized Earth's climate. This work demonstrates that forward modeling the entirety of Earth's history with relatively few imposed boundary forcings is feasible, that the Earth system is not at steady state, and that our understanding of coupled C‐N‐P‐O cycling as it functions today can explain much of the Earth's evolution. Plain Language Summary: The Earth is an interconnected system of biological, geological, and atmosphere‐ocean chemical systems responding to and influencing one another. We have developed a new model of our planet's chemical evolution, Earth's Oxygenation and Natural Systematics (EONS); this first of its kind model encompasses the entire lifetime of Earth's biosphere and major evolutionary developments therein, including the emergence of oxygen producing organisms and the colonization of continents by plants. Our basic (nominal) model run, starting 4 billion years ago and allowing biogeochemical systems to dynamically evolve until the modern day, agrees with geochemical evidence for rising atmospheric oxygen in magnitude and timing. It successfully reproduces atmosphere‐ocean chemistry and geologic systems in the modern context. Model output implies that the delay in oxygen's rise after the evolution of photosynthesis is caused by gradual burial of organic matter onto continents, depriving biological systems of key nutrients. Results also suggest that developments in the biosphere significantly disrupted Earth's climate. This model is a significant step forward in using coupled systematics to describe Earth's long‐term evolution. This work demonstrates that our planet is an immensely intertwined web of chemical relationships in a constant state of change, but one that can be fundamentally disentangled and understood. Key Points: The first fully coupled evolutionary C‐N‐O‐P box model spanning all major eons produces a surface oxygenation curve consistent with proxiesThe biosphere is a primary driver of Earth system evolution; increasing organic carbon burial and nutrient sequestration delay oxygen's riseThe chemical composition of the atmosphere‐ocean is never in steady state, due to the long timescales of geological and stellar evolution [ABSTRACT FROM AUTHOR]

The article explores the Shuram Excursion (SE), a major event in Earth's history that occurred during the Ediacaran Period around 570 million years ago. The SE is characterized by a significant drop in carbon isotope values and a decoupling between carbon isotope compositions. The article presents evidence that the SE was caused by the massive oxidation of organic matter in the oceans, which released phosphorus and resulted in changes in various isotopic systems. The text emphasizes the importance of technological advancements in understanding the nature of the SE and discusses the implications of this research for the evolution of early complex life and the carbon cycle of ancient oceans. [Extracted from the article]

This editorial provides an overview of a special issue titled "State of the Art in Molecular Catalysis in Europe" in the journal Catalysts. The issue includes eleven contributions covering a wide range of topics related to heterogeneous and homogeneous catalysis. Two reviews discuss the catalytic aspects of Zn-air batteries and organic dyes, while the remaining nine scientific research papers focus on topics such as palladium catalysts, acid hydrolysis/dehydration, and catalysts for polymerization processes. The authors express their gratitude to the contributors and hope that readers will enjoy the special issue. [Extracted from the article]

Enhanced continental phosphorus input into the ocean has been suggested as a potential trigger for the transient oxygenation events during the mid‐Proterozoic; however, the response of phosphorus cycling to these marine oxygenations remains unclear. Here, we report the changes in phosphorus cycling associated with a ∼1.7 Ga transient oxygenation. Abundant authigenic aluminum phosphate–sulfate mineral svanbergite (SrAl3(PO4) (SO4) (OH)6; 8.02 ± 4.92 wt%) is identified within the ∼1.7 Ga Yunmengshan ironstones from the Xiong'er Basin, North China and other contemporaneous basins. This observation provides new evidence to support the suggestion that early diagenetic aluminum phosphate‐sulfate minerals could have represented a critical sink of marine phosphorus during the Proterozoic. We suggest that atmospheric oxygenation and concomitant changes in porewater redox chemistry may have enhanced the formation of early diagenetic phosphates, leading to a negative feedback on the oceanic phosphorus reservoir and atmospheric oxygen levels. Plain Language Summary: It becomes increasingly clear that multiple transient oxygenation events likely punctuated the low background oxygen world during the mid‐Proterozoic. This may imply that a negative feedback could have inhibited a secular rise in atmospheric oxygen, though the deoxygenation mechanisms remain unclear. Phosphorus (P) availability regulated primary production and therefore controlled the atmospheric oxygen levels during this time, and oxygenation would in turn affect phosphorus cycling. Here we investigate the P cycling during a ca. 1.7 Ga transient oxygenation using mineralogical and geochemical methods. The results show an enhanced phosphorus burial during this transient oxygenation. The elevated phosphorus and sulfate inputs from the enhanced continental weathering and oxygenation may have promoted the formation of aluminum phosphate‐sulfate minerals. This, in turn, reduced the bio‐availability of phosphorus in the marine environment, ultimately limiting marine productivity and leading to a negative feedback on the oxygenation event. This study highlights that phosphorus cycling pathway, which was previously overlooked, may have played a role in the deoxygenation during the intermittent oxygenation events in the mid‐Proterozoic. Key Points: Abundant phosphorus and sulfur precipitation as authigenic svanbergite is associated with the ∼1.7 Ga transient oxygenationThe oxygenation resulted in suboxic and acidic porewater conditions rich in P‐ and sulfate, facilitating the authigenesis of svanbergiteThe enhanced P and S burial as svanbergite represents a significant but overlooked negative feedback during the transient oxygenation [ABSTRACT FROM AUTHOR]

The temporal relationship between global glaciations and the Great Oxidation Event (GOE) suggests that climate change played an important role in Earth's oxygenation. The potential role of temperature is captured by the stratigraphic proximity between glacial deposits and sediments containing mass‐independent fractionation of sulfur isotopes (MIF‐S). We use a time‐dependent one‐dimensional photochemical model to investigate whether temperature changes associated with global glaciations can drive oscillations in atmospheric O2 levels and MIF‐S production across the GOE. We find that extreme climate change can cause atmospheric O2 to oscillate between pre (<10−6 times the present atmospheric level, PAL) and post‐GOE (>10−5 PAL) levels. Post‐glacial hot‐moist greenhouse climates lead to post‐GOE O2 levels because the abundant H2O vapor and oxidizing radicals drive the depletion of reduced species. This pattern is generally consistent with the MIF‐S signal observed in the sedimentary record, suggesting a link between global glaciations and O2 oscillations across the GOE. Plain Language Summary: The Great Oxidation Event was the most significant environmental and chemical transformation in Earth's history, marking the first time oxygen accumulated in the atmosphere around 2.4 billion years ago. Oxygen increased from below one millionth (low) to at least one‐thousandth of a percent (intermediate) of the present oxygen concentration during this event. However, measurements of geochemical oxygen proxies suggest that oxygen levels oscillated between low and intermediate levels before stabilizing after this event. The first rise of atmospheric oxygen occurred during a period of extreme climate variability indicated by the presence of glacial rock deposits around this time. In this study, we use a time‐dependent photochemical model to show that extreme temperature changes caused by global glaciations can drive oscillations in atmospheric oxygen levels across the Great Oxidation Event (GOE). Our results can help explain why atmospheric oxygen shows drastic changes across the GOE in a way that is consistent with the geochemical record. Key Points: Across the Great Oxidation Event (GOE), extreme climate change linked to global glaciations can drive oscillations in atmospheric O2 levels and mass‐independent fractionation of sulfur isotopes (MIF‐S) productionGlacial climates and hot‐moist greenhouse climates were likely characterized by pre‐GOE and post‐GOE O2 levels respectivelyTemperature changes associated with global glaciations can help explain the MIF‐S record across the GOE [ABSTRACT FROM AUTHOR]

Eukaryotes originated prior to the establishment of modern marine oxygen (O2) levels. According to the body fossil and lipid biomarker records, modern (crown) microbial eukaryote lineages began diversifying in the ocean no later than ~800 Ma. While it has long been predicted that increasing atmospheric O2 levels facilitated the early diversification of microbial eukaryotes, the O2 levels needed to permit this diversification remain unconstrained. Using time-resolved geochemical parameter and gene sequence information from a model marine oxygen minimum zone spanning a range of dissolved O2 levels and redox states, we show that microbial eukaryote taxonomic richness and phylogenetic diversity remain the same until O2 declines to around 2 to 3% of present atmospheric levels, below which these diversity metrics become significantly reduced. Our observations suggest that increasing O2 would have only directly promoted early crown-eukaryote diversity if atmospheric O2 was below 2 to 3% of modern levels when crown-eukaryotes originated and then later met or surpassed this range as crown-eukaryotes diversified. If atmospheric O2 was already consistently at or above 2 to 3% of modern levels by the time that crown-eukaryotes originated, then the subsequent diversification of modern microbial eukaryotes was not directly driven by atmospheric oxygenation. [ABSTRACT FROM AUTHOR]

A growing body of observations reveals rapid changes in both the total inventory and distribution of marine oxygen over the later half of the 21st century, leading to increased interest in extending oxygenation records into the past. Use of paleo-oxygen proxies have the potential to extend the spatial and temporal range of current records, bound pre-anthropogenic baselines, provide datasets necessary to test climate models under different boundary conditions, and ultimately understand how ocean oxygenation responds beyond decadal scale changes. This review seeks to summarize the current state-ofknowledge about proxies for reconstructing Cenozoic marine oxygen: sedimentary features, sedimentary redox-sensitive trace elements and isotopes, biomarkers, nitrogen isotopes, foraminiferal trace elements, foraminifera assemblages, foraminifera morphometrics, and benthic foraminifera carbon isotope gradients. Taking stock of each proxy reveals some common limitations in that the majority of proxies function best at low-oxygen concentrations and many reflect multiple environmental drivers. We also highlight recent breakthroughs in geochemistry and proxy approaches for constraining pelagic (in addition to benthic) oxygenation that are rapidly advancing the field. In light of both the emergence of new proxies and the persistent multiple driver problem, the need for multi-proxy approaches and FAIR data storage and sharing is emphasized. Continued refinement of proxy approaches and both proxy-proxy and proxy-model comparisons are likely to support the growing needs of both oceanographer and paleoceanographers interested in paleo-oxygenation records. [ABSTRACT FROM AUTHOR]

A growing body of observations reveals rapid changes in both the total inventory and distribution of marine oxygen over the later half of the 21st century, leading to increased interest in extending oxygenation records into the past. Use of paleo-oxygen proxies have the potential to extend the spatial and temporal range of current records, bound pre-anthropogenic baselines, provide datasets necessary to test climate models under different boundary conditions, and ultimately understand how ocean oxygenation responds beyond decadal scale changes. This review seeks to summarize the current state-of-knowledge about proxies for reconstructing Cenozoic marine oxygen: sedimentary features, sedimentary redox-sensitive trace elements and isotopes, biomarkers, nitrogen isotopes, foraminiferal trace elements, foraminifera assemblages, foraminifera morphometrics, and benthic foraminifera carbon isotope gradients. Taking stock of each proxy reveals some common limitations in that the majority of proxies function best at low-oxygen concentrations and many reflect multiple environmental drivers. We also highlight recent breakthroughs in geochemistry and proxy approaches for constraining pelagic (in addition to benthic) oxygenation that are rapidly advancing the field. In light of both the emergence of new proxies and the persistent multiple driver problem, the need for multi-proxy approaches and FAIR data storage and sharing is emphasized. Continued refinement of proxy approaches and both proxy-proxy and proxy-model comparisons are likely to support the growing needs of both oceanographer and paleoceanographers interested in paleo-oxygenation records. [ABSTRACT FROM AUTHOR]

Direct electrochemical propylene epoxidation by means of water-oxidation intermediates presents a sustainable alternative to existing routes that involve hazardous chlorine or peroxide reagents. We report an oxidized palladium-platinum alloy catalyst (PdPtOx/C), which reaches a Faradaic efficiency of 66 ± 5% toward propylene epoxidation at 50 milliamperes per square centimeter at ambient temperature and pressure. Embedding platinum into the palladium oxide crystal structure stabilized oxidized platinum species, resulting in improved catalyst performance. The reaction kinetics suggest that epoxidation on PdPtOx/C proceeds through electrophilic attack by metal-bound peroxo intermediates. This work demonstrates an effective strategy for selective electrochemical oxygen-atom transfer from water, without mediators, for diverse oxygenation reactions. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of a heavy-atom-free BODIPY dye called carbonyl-BDP and its application in the photooxygenation of 1-naphthol to 1,4-naphthoquinone. BODIPY dyes are known for their strong visible-light absorption and good photochemical and thermal stabilities, making them suitable for organic transformations. The introduction of carbonyl groups into the BODIPY system enhances its ability to generate singlet oxygen, which is important for photocatalytic reactions. The researchers successfully demonstrated the photooxygenation of 1-naphthol using carbonyl-BDP as a photosensitizer under white-light irradiation. [Extracted from the article]

Unveiling the tempo and mode of animal evolution is necessary to understand the links between environmental changes and biological innovation. Although the earliest unambiguous metazoan fossils date to the late Ediacaran period, molecular clock estimates agree that the last common ancestor (LCA) of all extant animals emerged ~850 Ma, in the Tonian period, before the oldest evidence for widespread ocean oxygenation at ~635–560 Ma in the Ediacaran period. Metazoans are aerobic organisms, that is, they are dependent on oxygen to survive. In low‐oxygen conditions, most animals have an evolutionarily conserved pathway for maintaining oxygen homeostasis that triggers physiological changes in gene expression via the hypoxia‐inducible factor (HIFa). However, here we confirm the absence of the characteristic HIFa protein domain responsible for the oxygen sensing of HIFa in sponges and ctenophores, indicating the LCA of metazoans lacked the functional protein domain as well, and so could have maintained their transcription levels unaltered under the very low‐oxygen concentrations of their environments. Using Bayesian relaxed molecular clock dating, we inferred that the ancestral gene lineage responsible for HIFa arose in the Mesoproterozoic Era, ~1273 Ma (Credibility Interval 957–1621 Ma), consistent with the idea that important genetic machinery associated with animals evolved much earlier than the LCA of animals. Our data suggest at least two duplication events in the evolutionary history of HIFa, which generated three vertebrate paralogs, products of the two successive whole‐genome duplications that occurred in the vertebrate LCA. Overall, our results support the hypothesis of a pre‐Tonian emergence of metazoans under low‐oxygen conditions, and an increase in oxygen response elements during animal evolution. [ABSTRACT FROM AUTHOR]

The conquest of land by arthropods is commonly believed to be a surface phenomenon associated with the arrival of photosynthetic plants, atmospheric oxygenation, and an ozone shield in the mid-Paleozoic Era. However, recent molecular and fossil evidence suggests terrestrial fauna may have first appeared in the Cambrian, before the proliferation of plants and ozone, which are thought to be essential for survival. This raises the question—how could arthropods survive on land without established plants and an ozone shield? We propose a hypothesis that chemolithoautotrophic cave ecosystems, independent of photosynthesis, may have served as a subsurface stepping stone, providing a possible explanation for the land invasion enigma. Chemolithoautrophic caves have offered abundant food and radiation protection, enabling ancient arthropods to evolve strategies to adapt to new frontiers through gradual dispersion from the sea to shielded cave waters, then to cave hygropetric margins of cave waters, and, finally, to the surface. [ABSTRACT FROM AUTHOR]

Climatic and environmental conditions play a pivotal role in the evolution of the biosphere, serving as the primary natural factors influencing biological evolution and the development of human civilization. The study of the evolution of Earth's habitability primarily revolves around the reconstruction of climatic and oceanic conditions in geohistorical periods, shedding light on their dynamic changes. This paper collates classic geological indicators and geochemical proxies associated with paleo-climatic and oceanic environmental conditions. The latest "big data" analyses and simulations made possible by the availability of previously unimagined massive datasets reveal several key findings: During the early Paleozoic, atmospheric oxygen levels were low, and widespread oceanic anoxia was prevalent; the Devonian era witnessed a greenhouse climate, followed by the Carboniferous ice age characterized by higher oceanic oxidation levels and alkalinity. The latest Paleozoic deglaciation occurred under high pCO2 conditions, extending into much of the Mesozoic and early Cenozoic, marked by multiple hyperthermal and anoxia expansion events, until the resurgence of global glaciation in the middle-late stages of the Cenozoic, ultimately bringing environmental and climatic conditions closer to modern levels. By correlating the aforementioned long-term trends with major geological events, we can delineate the co-evolution of paleoclimate and oceanic environments in tandem with the development of Tethys tectonics as follows. (1) During the Proto-Tethys stage, global paleo-elevations were relatively low, and atmospheric oxygen levels were also relatively modest. Despite the occurrence of significant tectonic movements that led to noticeable transgressive-regressive cycles, their effects on climate and oceanic environments were somewhat limited due to the relatively weak interactions. (2) The emergence of the Paleo-Tethys was a significant event that coincided with the formation of the supercontinent Pangaea. Intensive orogenic movements during this period increased the global land area and elevation. This, in turn, led to enhanced terrestrial weathering, which elevated sea surface productivity and resulted in massive nutrient input into the oceans. Consequently, this process contributed to the rise of oxygen levels in the atmosphere and a decrease in atmospheric pCO2. These changes are considered potential driving mechanisms for late Paleozoic glaciation and oceanic oxygenation. (3) The transition from the Paleo-Tethys to the Neo-Tethys was closely linked to the breakup of Pangaea. During this period, the terrestrial weathering processes were relatively weak due to decreased continental elevations. This resulted in a long-term greenhouse climate and intermittent global oceanic events, which were responses to the high atmospheric pCO2 levels during the Mesozoic and early Cenozoic eras. (4) The Neo-Tethys stage ended with the dramatic uplift of the Alps-Himalaya Mountain ranges due to the collision of India and Asia. This uplift had a profound global impact, significantly increasing continental elevations. As a result, weathering and carbon burial processes intensified, leading to a reduction in atmospheric pCO2. Concurrently, this uplift played a crucial role in the establishment of the East Asian monsoon and North Atlantic deep-water circulations, both of which played a part in triggering the late Cenozoic ice age. These models suggest that the teleconnections between land and sea (orogeny-terrestrial weathering-marine carbon burial) span over the whole Phanerozoic and might have played a key role in balancing the Earth surface system. Combined, the tectonic, volcanic, paleo-climatic, as well as paleoenvironmental events recorded in the Tethys oceans and adjunct continents represent valuable natural experiments and lessons for understanding the present and the future of Earth's habitability. [ABSTRACT FROM AUTHOR]

The Cambrian explosion is a critical evolutionary milestone in life history, but the mechanistic relationship between the Cambrian explosion, rising atmospheric and oceanic oxygen levels, and the primary productivity remains controversial. Here, we present new mercury (Hg) isotope data from Cambrian marine sediments of the ∼521–514 Ma Yu'anshan and Shuijingtuo Formations (Nanhua Basin, South China), which preserve the famous ∼518 Ma Chengjiang and Qingjiang Cambrian Biotas, respectively. We find evidence that, prior to Cambrian animal diversification, local terrestrial and/or atmospheric inputs are important drivers of Hg enrichment in the shallow shelf Yu'anshan and Shuijintuo Formations. Elevated Hg and total organic carbon (TOC) concentrations of coeval deeper shelf and slope sections of the Niutitang Formation are mainly attributed to upwelling of Hg associated with dissolved organic carbon (Hg-DOC) from pelagic seawater, unrelated to locally high primary productivity. During the deposition of fossiliferous strata, negative shifts of Δ199Hg and δ202Hg values in the shallow water shelf shales from the Shuijingtuo Formation, combined with similar Hg isotope characteristics in the deeper shelf and slope shales, demonstrate a significant shallow and deep-water oxygenation event took place in the Nanhua Basin. A comparable negative shift of Δ199Hg values occurs in coeval Indian Craton sediments, suggesting this oxygenation event could be regional, or possibly even global, in scale. Our newly-collected Hg isotope data provide strong evidence that rising molecular oxygen levels in both surface and deep seawater are associated with enhanced marine primary productivity and could be a critical driver of the Cambrian explosion. Finally, we also argue that Hg isotopes are an emerging and promising redox proxy for studies of Precambrian seawater, but the chemical response of Hg to atmospheric and ocean oxygenation requires further calibration. [ABSTRACT FROM AUTHOR]

The Precambrian‐Cambrian (Pc‐C) boundary marks significant biological, atmospheric, and oceanic changes. These changes include extinction of the Ediacaran fauna, initiation of complex lifeforms, and oxygenation of the atmosphere and oceans. In this contribution, elemental and Mo‐S isotopic compositions of organic‐rich shales overlying the Pc‐C boundary from the Tal Formation, Lesser Himalaya, have been investigated. These datasets are used to reconstruct past oceanic redox state and sulfate concentrations. The principal component analysis of the elemental dataset identifies six major factors, with factors associated with organic matter and sulfide phases accounting for about half of the total variance. Iron speciation and Mo/U data suggest that the shales were deposited in anoxic and ferruginous deep water conditions. The δ98Mo data (1.5 ± 0.2‰) and their mass balance calculations indicate that the areal extent of sulfidic waters and pyrite burial rates were about 2–4 times higher during the Pc‐C transition than in the modern ocean. The pyrite‐δ34S values (3.6–8.3‰) for the Tal shales are isotopically heavier compared to modern‐day sedimentary pyrites (∼−21‰). Calculations involving earlier‐reported δ34S values for early Cambrian seawater and our measured pyrite‐δ34S data estimate the seawater sulfate concentration (8 ± 3 mM) during their deposition. This sulfate value for the Tal basin is higher than that reported for the late Neoproterozoic ocean (<5 mM), attributable to increasing oxygen availability and continental supply during this time. The observed basinal conditions and high terrestrial input may have influenced metazoan diversification. Key Points: Chemical and Mo‐S isotopic study of black shales overlying the Pc‐C boundary from the Tal Formation (Lesser Himalaya) was carried outTrace element, Fe‐speciation and Mo isotopic data suggest a stratified basin with anoxic and ferruginous bottom water conditionsHigher seawater sulfate (∼8 mM) during the Pc‐C transition (than Proterozoic) linked to atmospheric oxygenation and enhanced riverine input [ABSTRACT FROM AUTHOR]

Prof. Ning Jiao and his research group at Beijing University's School of Pharmacy have developed a new electron donor-acceptor catalytic system called EDA Complex. This system allows for the synthesis of target compounds through electron transfer under light irradiation, without the need for a photocatalyst. The researchers have demonstrated the potential applications of this system in various important synthetic chemistry fields, including boronation, amination, sulfuration, alkylation, cyclization, and coupling reactions. The EDA Complex system shows promise for selective and efficient aerobic oxygenation reactions, with potential applications in the development of new cancer drugs. The research paper, authored by Dr. Wei Jialiang and Professor Jiao Ning, focuses on the development of pharmaceutical drugs using oxygen activation reactions and photodynamic therapy. The authors have published multiple papers in reputable journals and have received recognition and awards for their work. [Extracted from the article]