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A key control on the magnitude of coastal eutrophication is the degree to which currents quickly transport nitrogen derived from human sources away from the coast to the open ocean before eutrophication develops. In the Southern California Bight (SCB), an upwelling-dominated eastern boundary current ecosystem, anthropogenic nitrogen inputs increase algal productivity and cause subsurface acidification and oxygen (O 2 ) loss along the coast. However, the extent of anthropogenic influence on eutrophication beyond the coastal band, and the physical transport mechanisms and biogeochemical processes responsible for these effects are still poorly understood. Here, we use a submesoscale-resolving numerical model to document the detailed biogeochemical mass balance of nitrogen, carbon and oxygen, their physical transport, and effects on offshore habitats. Despite management of terrestrial nutrients that has occurred in the region over the last 20 years, coastal eutrophication continues to persist. The input of anthropogenic nutrients promote an increase in productivity, remineralization and respiration offshore, with recurrent O 2 loss and pH decline in a region located 30-90 km from the mainland. During 2013 to 2017, the spatially averaged 5-year loss rate across the Bight was 1.3 mmol m -3 O 2 , with some locations losing on average up to 14.2 mmol m -3 O 2 . The magnitude of loss is greater than model uncertainty assessed from data-model comparisons and from quantification of intrinsic variability. This phenomenon persists for 4 to 6 months of the year over an area of 278,40 km 2 ( ∼ 30% of SCB area). These recurrent features of acidification and oxygen loss are associated with cross-shore transport of nutrients by eddies and plankton biomass and their accumulation and retention within persistent eddies offshore within the SCB.

Mineral-rich hardgrounds, such as ferromanganese (FeMn) crusts and phosphorites, occur on seamounts and continental margins, gaining attention for their resource potential due to their enrichment in valuable metals in some regions. This study focuses on the Southern California Borderland (SCB), an area characterized by uneven and heterogeneous topography featuring FeMn crusts, phosphorites, basalt, and sedimentary rocks that occur at varying depths and are exposed to a range of oxygen concentrations. Due to its heterogeneity, this region serves as an optimal setting for investigating the relationship between mineral-rich hardgrounds and benthic fauna. This study characterizes the density, diversity, and community composition of macrofauna (>300 μm) on hardgrounds as a function of substrate type and environment (depth and oxygen ranges). Rocks and their macrofauna were sampled quantitatively using remotely operated vehicles (ROVs) during expeditions in 2020 and 2021 at depths above, within, and below the oxygen minimum zone (OMZ). A total of 3,555 macrofauna individuals were counted and 416 different morphospecies (excluding encrusting bryozoans and hydrozoans) were identified from 82 rocks at depths between 231 and 2,688 m. Average density for SCB macrofauna was 11.08 ± 0.87 ind. 200 cm-2 and mean Shannon-Wiener diversity per rock (H[loge]) was 2.22 ± 0.07. A relationship was found between substrate type and macrofaunal communities. Phosphorite rocks had the highest H of the four substrates compared on a per-rock basis. However, when samples were pooled by substrate, FeMn crusts had the highest H and rarefaction diversity. Of all the environmental variables examined, water depth explained the largest variance in macrofaunal community composition. Macrofaunal density and diversity values were similar at sites within and outside the OMZ. This study is the first to analyze the macrofaunal communities of mineral-rich hardgrounds in the SCB, which support deep-ocean biodiversity by acting as specialized substrates for macrofaunal communities. Understanding the intricate relationships between macrofaunal assemblages and mineral-rich substrates may inform effects from environmental disruptions associated with deep-seabed mining or climate change. The findings contribute baseline information useful for effective conservation and management of the SCB and will support scientists in monitoring changes in these communities due to environmental disturbance or human impact in the future.

Predicting the dissolved oxygen concentration and identifying its driving factors are essential for improved prevention and management of anoxia in estuaries. However, complex hydrodynamic conditions and the limitations in traditional methods result in challenges in the identification of the driving factors for the low dissolved oxygen (DO) phenomenon. The objective of our study is to develop a robust deep learning model using four-year in situ data collected from an automatic water quality monitoring station (AWQMS) in an estuary, for accurate identification and quantification of the driving factors influencing DO levels. Mitigations in hypoxia were observed during the initial two years, but a subsequent decline in DO concentrations was witnessed recently. The periodicity of DO concentrations in the Pearl River Estuary reduced with the increase in the hypoxic intensity. Maximal information coefficient (MIC) and extreme gradient boosting (XGBoost) were employed to determine the significance of input variables, which were subsequently validated by using the long- and short-term memory networks (LSTMs). The driving factors contributing to the hypoxia problem were shown as temperature, pH, conductivity, and NH4+-N concentrations. Notably, the evaluation index values of the hybrid model are MAPE = 0.0887 and R2 = 0.9208, which have been improved compared with the LSTM model by about 99.34% in MAPE reduction and 16.56% in R2 improvement, indicating that the MixUp-LSTM model was capable of effectively capturing nonlinear relationships between DO and other water quality indicators. Based on existing literature, three traditional statistical methods and four machine learning models were also performed to compare with the proposed MixUp-LSTM model, which outperformed other models in terms of prediction accuracy and robustness. Overall, the successful identification of the driving factors for the deoxygenation phenomenon would have important implications for the governance and regulation of low DO in estuaries. [ABSTRACT FROM AUTHOR]

Herein, we disclosed a protocol for the deoxygenation of allyl arylsulfones to access the corresponding thioethers under photoredox conditions by a "cut-sew" strategy. The key to the success of the deoxygenation process is using triarylphosphines not only as the terminal reductants, but also as the reaction initiators. Deeper understanding of this deoxygenation process enabled the intermolecular deoxygenative allylation. [ABSTRACT FROM AUTHOR]

Ocean deoxygenation and standing levels of hypoxia are shrinking fundamental niches, particularly in coastal areas, yet documented repercussions on species development and behaviour are limited. Here, we tackled the impacts of deoxygenation (7 mg O2 l−1), mild hypoxia (nocturnal 5 mg O2 l−1) and severe hypoxia (nocturnal 2 mg O2 l−1) on cuttlefish (Sepia officinalis) development (hatching success, development time, mantle length), cognition (ability to learn individually and socially) and behaviour (ability to camouflage and to explore its surroundings spatially). We found that hypoxia yielded lower survival rates, smaller body sizes and inhibited predatory (increased latency to attack the prey) and anti-predator (camouflage) behaviours. Acute and chronic exposure to low oxygen produced similar effects on cognition (inability to socially learn, increased open-field activity levels, no changes in thigmotaxis). It is thus expected that, although cuttlefish can withstand oxygen limitation to a certain degree, expanding hypoxic zones will diminish current habitat suitability. [ABSTRACT FROM AUTHOR]

Urea electrosynthesis from co‐electrolysis of NO3− and CO2 (UENC) provides an alternative route for realizing efficient and sustainable urea production. In this work, single‐atom Ru dispersed on Co (Ru1Co) is demonstrated as an effective and robust catalyst for the UENC. In situ spectroscopic measurements and theoretical simulations unravel the cooperative effect of Ru1 and Co sites to promote the UENC process via a tandem catalysis mechanism, where the Ru1 site activates the adsorption and hydrogenation of NO3− to form *NH2, while the Co site activates the adsorption and hydrogenation/deoxygenation of CO2 to form *CO. The generated *CO is then transferred from the Co site to the nearby Ru1 site which promotes the C─N coupling of *NH2 and *CO toward the urea formation. Strikingly, Ru1Co assembled in a flow cell shows the highest urea‐Faradaic efficiency of 50.1% with the corresponding urea yield rate of 22.34 mmol h−1 g−1 at −0.5 V (RHE), superior to most reported UENC catalysts for urea production. [ABSTRACT FROM AUTHOR]

Upon constant photo-excitation, the phosphorescence intensities of long-lived triplet emitters dissolved in sulfoxide solvents under air exhibit periodic oscillations with regulatable frequencies and amplitudes, which is attributed to the interplay between photochemical deoxygenation and Rayleigh–Bénard convections. [ABSTRACT FROM AUTHOR]

Considering the substantial role of ammonia, developing highly efficient electrocatalysts for nitrate‐to‐ammonia conversion has attracted increasing interest. Herein, we proposed a feasible strategy of p–d orbital hybridization via doping p‐block metals in an Ag host, which drastically promotes the performance of nitrate adsorption and disassociation. Typically, a Sn‐doped Ag catalyst (SnAg) delivers a maximum Faradaic efficiency (FE) of 95.5±1.85 % for NH3 at −0.4 V vs. RHE and reaches the highest NH3 yield rate to 482.3±14.1 mg h−1 mgcat.−1. In a flow cell, the SnAg catalyst achieves a FE of 90.2 % at an ampere‐level current density of 1.1 A cm−2 with an NH3 yield of 78.6 mg h−1 cm−2, during which NH3 can be further extracted to prepare struvite as high‐quality fertilizer. A mechanistic study reveals that a strong p–d orbital hybridization effect in SnAg is beneficial for nitrite deoxygenation, a rate‐determining step for NH3 synthesis, which as a general principle, can be further extended to Bi‐ and In‐doped Ag catalysts. Moreover, when integrated into a Zn‐nitrate battery, such a SnAg cathode contributes to a superior energy density of 639 Wh L−1, high power density of 18.1 mW cm−2, and continuous NH3 production. [ABSTRACT FROM AUTHOR]

An efficient route for the chemoselective deoxygenation of benzylphenyl sulfones to the corresponding sulfides has been developed using a mixture of 1,2-bis(diphenylphosphino)ethane(dppe) and NBS as an effective promoter. This is the first development on the deoxygenation of diverse benzylphenyl sulfones under metal-free conditions. The mild reaction conditions, formation of the water soluble by-product and tolerance of a wide range of functional groups promote its broad applications in organic synthesis. [ABSTRACT FROM AUTHOR]

The deoxygenation process in water used in well injection operations is an important matter to eliminate corrosion in the petroleum industry. This study used molecular dynamics simulations to understand the behavior of siloxane surfaces by studying the surface properties with two functional groups attached to the end of siloxane and their effect on the deoxygenation process. The simulations were performed using LAMMPS to characterize surface properties. Jmol software version 14 was used to generate siloxane chains with (8, 20, and 35) repeat units. We evaluated properties such as total energy, surface tension, and viscosity. Then, we used siloxane as a membrane to compare the efficiency of deoxygenation for both types of functional groups. The results indicated that longer chain lengths increased the total energy and viscosity while decreasing surface tension. Replacing methyl groups with trifluoromethyl (CF3) groups increased all the above mentioned properties in varying proportions. Trifluoromethyl (CF3) groups showed better removal efficiency than methyl (CH3) groups but allowed more water to pass. Furthermore, the simulations were run using the class II potential developed by Sun, Rigby, and others within an explicit-atom (EA) model. This force field is universally applicable to the atomistic simulation of polymers, inorganic small molecules, and common organic molecules. [ABSTRACT FROM AUTHOR]

Diffusive equilibrium in thin films (DET) probes are passive samplers that are designed to reflect in situ porewater concentrations. In this study, we show that the gel and the plastic housing of DET probes store a substantial amount of oxygen (O2) that affects the chemical composition of porewater. To ensure complete deoxygenation, DET probes need to be treated for 7 d with continuous nitrogen flow. Such fully deoxygenated probes can be handled in the air (exposure time: < 90 s) and deployed to sediments through oxic water (exposure time: < 2 s) without significant ad(b)sorption of O2. Furthermore, we deployed a set of untreated (i.e., in equilibrium with atmospheric O2) and a set of fully deoxygenated DET probes to lake sediments. The O2 present in untreated DET probes altered iron (Fe) and phosphate (P) porewater profiles significantly. This is caused by the oxidation, immobilization, and accumulation of redox‐sensitive Fe (oxyhydr)oxides in the probe over time. Since P has a high binding affinity to Fe (oxyhydr)oxides, it is not in equilibrium with the porewater and is overestimated as well. Our results highlight the importance of thorough deoxygenation of DET probes before deployment in sediments, especially when addressing redox‐sensitive porewater species. [ABSTRACT FROM AUTHOR]

Cyclophellitol is a potent and selective mechanism‐based retaining β‐glucosidase inhibitor that has served as a versatile starting point for the development of activity‐based glycosidase probes (ABPs). We developed routes of synthesis of eight mono‐ and dideoxycyclophellitols and cyclophellitol aziridines, the latter as ABPs carrying either a biotin or fluorophore linked to the aziridine nitrogen. We reveal the potency of these 24 compounds as inhibitors of the three human retaining β‐glucosidases, GBA1, GBA2 and GBA3. We show that 3,6‐dideoxy‐β‐galacto‐cyclophellitol aziridine selectively captures GBA3 over GBA1 and GBA2 in extracts of cells overexpressing both GBA2 and GBA3. We also identify a probe that selectively labels GBA1 and GBA2 over GBA3 at lower concentrations. In sum, the here‐presented studies reveal new chemistries to prepare chiral, substituted cyclitol epoxides and aziridines, add to the growing suite of cyclophellitols varying in configuration and substitution pattern, and yielded a reagent that may find use to investigate the physiological role and therapeutic relevance of the most elusive of the three retaining β‐glucosidases: GBA3. [ABSTRACT FROM AUTHOR]

Being touched by others (social-touch) and touching oneself (self-touch) are common nonverbal behaviors in everyday interaction. The commonalities and differences between these two types of touching behavior are of particular interest for conditions when social-touch is substantially restricted such as during the corona pandemic. Neuropsychologically, pleasant social-touch is associated with increased activation in frontal brain regions such as frontopolar, dorsolateral prefrontal (dlPFC), and orbitofrontal cortices (OFC). However, for these regions a deactivation has also been reported. Likewise, for self-touch the findings are controversial. Therefore, the aim of this study is to shed light on the controversial findings and to elucidate the relation between self-touch and social-touch. From 2021 to 2022, in a quasi-naturalistic setting, in forty-six participants brain oxygenation and deoxygenation was examined during social-touch and self-touch in frontal cortices applying functional NearInfraRed Spectroscopy (fNIRS). Social-touch compared to self-touch led to a significantly higher brain deoxygenation in the frontopolar areas and in parts of the dlPFC and OFC. In contrast, brain oxygenation in the PFC was significantly increased during self-touch compared to social-touch. The cerebral activation and deactivation pattern in a quasi-naturalistic setting indicates that self-touch cannot achieve the hedonic effects of social-touch, but it can influence internally self-regulating processes. [ABSTRACT FROM AUTHOR]

In recent years, the fully oxygen‐tolerant reversible deactivation radical polymerization (RDRP) has become a highly researched area. In this contribution, a new and minimalist method is successfully employed to accomplish fully oxygen‐tolerant reversible addition‐fragmentation chain transfer (RAFT) polymerization using bis(trithiocarbonate) disulfides (BisTTC) as an iniferter agent, where the released sulfur‐centered trithiocarbonate (TTC) radical can initiate monomer. Furthermore, polymerization kinetics revealed the typical "living" features of this polymerization system. More importantly, by high‐throughput screening, it is found that dodecyl‐substituted TTC is responsible for the fully oxygen‐tolerant RAFT polymerization though trithiocarbonate radical initiation and R radical deoxygenation. It is believed that trithiocarbonate radical initiation strategy provides a powerful and minimalist tool for fully oxygen‐tolerant RDRPs. [ABSTRACT FROM AUTHOR]

Ocean oxygen content is decreasing with global change. A major challenge for modelling future declines in oxygen concentration is our lack of knowledge of the natural variability associated with marine oxygen inventory on interannual and multidecadal timescales. Here, we present 10 annually resolved 200 year-long records of denitrification, a marker of deoxygenation, from a varved sedimentary archive in the North Pacific oxygen minimum zone covering key periods over the last glacial–interglacial cycle. Spectral analyses on these records reveal strong signals at periodicities typical of today's Atlantic multidecadal oscillation. Modern subsurface circulation reanalyses regressed on the positive Atlantic and Pacific Climatic Oscillation indices further confirm that North Atlantic temperature patterns are the main control on the subsurface zonal circulation and therefore the most likely dominant driver of oxygen variability in the tropical Pacific. With currently increasing temperatures in the Northern Hemisphere high latitudes and North Atlantic, we suggest deoxygenation will intensify in the region. This study provides the longest annually resolved records of deoxygenation and productivity in the tropical Pacific and highlights the importance of North Atlantic climate oscillations on Pacific oxygen via its impact on the Pacific equatorial shallow overturning. [ABSTRACT FROM AUTHOR]

Rapid and efficient synthesis of targeted deoxygenated glycosides is highly desired. Herein, we disclose a two‐step procedure for the synthesis of deoxysugars from partially protected pyranosides via site‐selective thiocarbonylation followed by tin‐free Barton–McCombie deoxygenation. The selectivity can be smoothly achieved through anhydrous FeCl3 as the catalyst assisted by low‐priced benzoyltrifluoroacetonate (Hbtfa) ligand in the presence of K2CO3 as base. Further deoxygenation can be carried out using greener silicon reagent, avoiding highly toxic organotin reagents in traditional procedures. Conspicuous features of this method include mild conditions, easy operation, high selectivity and non or low toxic reagents, making it a more attractive strategy. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the potential for producing an aromatic hydrocarbon-enriched fuel from Scenedesmus sp. microalgae using low-cost zeolite in catalytic flash pyrolysis. The methodology adopted in this study involved the use of an analytical micropyrolyzer coupled with a gas chromatograph/mass spectrometer at 500 ºC to assess the effectiveness of the low-cost HZSM − 5 catalyst in deoxygenation, denitrogenation, and aromatization activities of volatile reaction products. The HZSM − 5 catalyst was synthesized using the hydrothermal method, employing low-cost precursor materials, rice husk ash, and diatomite residue as alternative silicon and aluminum sources. The oxygenated and nitrogenated volatile products in non-catalytic flash pyrolysis constituted 51.7% and 15.3%, respectively. Catalytic upgrading of pyrolysis vapors from Scenedesmus sp. microalgae was demonstrated by significant deoxygenation and denitrogenation activity, reaching up to 99%, while chemical industry-relevant classes experienced increased proportions: aromatic hydrocarbons by 5.8-fold, and aliphatic hydrocarbons by 1.7-fold. Around 78% selectivity for aromatic hydrocarbons was achieved, predominantly yielding BTEX (benzene, toluene, ethylbenzene, and xylene). Another significant finding is that 89.8% of the renewable hydrocarbons produced fall within the gasoline range (C5 − C12). This study conclusively indicates that the low-cost HZSM − 5 catalyst shows significant promise for producing high-quality bio-oil through the flash pyrolysis of Scenedesmus sp. microalgae. [ABSTRACT FROM AUTHOR]

Catalytic oxygen removal applying a commercial CoMo‐based catalyst has attracted scientific attention owing to its catalytic stability towards poisoning components and cost‐effectiveness. The catalytic performance of the CoMo catalyst was investigated using statistical optimization techniques. The H2S concentrations in the sulfidation and reaction mixture are the key factors regulating the optimal values of deoxygenation reaction. The sulfidation process is a key step to generate the active species. The catalyst remains active in the presence of sulfur compounds in the reaction mixture, which is poisoning for other catalyst systems. An increase in the H2S content enhances the catalytic activity via in‐situ sulfidation within the meaning of regeneration during the reaction. Concentrations above 450 ppm H2S in the reaction mixture result in a nearly complete oxygen conversion and ensure the catalytic stability. At the same time, an increase in the H2S content favors a high sulfidation degree resulting in the formation of active sites. [ABSTRACT FROM AUTHOR]

The spread of marine anoxia is believed to have played a key role in the development of the SPICE (Steptoean Positive Carbon Isotope Excursion) event and the end-Marjuman extinction in the late Cambrian (∼497.5 m.y. ago), but their cause-and-effect relationship is poorly constrained. Here we present an integrated analysis of carbonate δ13C, cerium anomalies (Ce/Ce*), and genus-level diversity data of trilobites from the North China Platform. Our results show tightly coupled changes between the SPICE, an increase in Ce/Ce*, and a trilobite turnover event, which we interpret as indicating enhanced productivity and organic remineralization, leading to the development of low-oxygen conditions in shallowwater settings. This study therefore establishes a direct link between local ecological stress and trilobite turnover during the global SPICE event. Furthermore, the presence of low-oxygen rather than fully anoxic conditions during the peak of the SPICE event could explain the nature of the end-Marjuman crisis, which was characterized by the replacement of shallowwater fauna by deeper-water counterparts that were potentially more tolerant of hypoxia. [ABSTRACT FROM AUTHOR]

We explore here, through reactive force field (ReaxFF) molecular dynamics simulations, oleic acid upgrading on beta zeolite (BEA) regulated with nine silica-to-aluminium ratios (SARs) to investigate their acid-catalyzed deoxygenation and coking susceptibility. The selected computational descriptors involved conversion, hydrodeoxygenation, and decarboxylation/decarbonylation selectivity, biofuels yield, and coke deposition characteristics. Simulations were validated by 20.3 SAR available experimental data and used for the systematic study. High deoxygenation selectivity was found to be related to the structural sensitivity of BEA(100) on the upgrading mechanism. ReaxFF simulations revealed that altering the Alsubstitution could greatly promote biofuel formation. Specifically, SARs towards the mid-region (SAR 47) favored gasoline production, while 31 SAR exploited diesel-like hydrocarbons. An optimum ratio of 37.4 SAR achieved maximum oleic acid conversion (69.8%), with high yields of gasoline and diesel fuels (15.6 and 20.4 wt%, respectively) and moderate coking (8.6 wt%). Density functional theory screening of metallic dopants allowed investigating of their deoxygenation and coke susceptibility, obtaining that Cu-BEA structure favored the optimal carbon and O-moiety adsorption (-3.89 and -1.8 eV, respectively). Furthermore, the economic and environmental analysis showed that Cu-dopped BEA displayed the lowest market price and global warming potential (71 USD/kg and 2.8 kg CO2-eq/kg). [ABSTRACT FROM AUTHOR]

We explore here, through reactive force field (ReaxFF) molecular dynamics simulations, oleic acid upgrading on beta zeolite (BEA) regulated with nine silica-to-aluminium ratios (SARs) to investigate their acid-catalyzed deoxygenation and coking susceptibility. The selected computational descriptors involved conversion, hydrodeoxygenation, and decarboxylation/decarbonylation selectivity, biofuels yield, and coke deposition characteristics. Simulations were validated by 20.3 SAR available experimental data and used for the systematic study. High deoxygenation selectivity was found to be related to the structural sensitivity of BEA(100) on the upgrading mechanism. ReaxFF simulations revealed that altering the Al-substitution could greatly promote biofuel formation. Specifically, SARs towards the mid-region (SAR 47) favored gasoline production, while 31 SAR exploited diesel-like hydrocarbons. An optimum ratio of 37.4 SAR achieved maximum oleic acid conversion (69.8%), with high yields of gasoline and diesel fuels (15.6 and 20.4 wt%, respectively) and moderate coking (8.6 wt%). Density functional theory screening of metallic dopants allowed investigating of their deoxygenation and coke susceptibility, obtaining that Cu-BEA structure favored the optimal carbon and O moiety adsorption (-3.89 and -1.8 eV, respectively). Furthermore, the economic and environmental analysis showed that Cu-dopped BEA displayed the lowest market price and global warming potential (71 USD/kg and 2.8 kg CO2-eq/kg).

A feasible strategy for boosting electrocatalytic ammonia synthesis from nitrate has been realized by integrating the unique effects of interfacial electric fields originating from asymmetric chemical potentials and local defects into binary Bi 2 S 3 -Bi 2 O 3 sublattices. This results in superior Faraday efficiency (FE) for ammonia production of 94% and a NH 3 yield rate of 89.83 mg g cat -1h−1 at −0.4 V vs. RHE. [Display omitted] The electrocatalytic nitrate reduction reaction (NO 3 − RR) has immense potential to alleviate the problem of groundwater pollution and may also become a key route for the environmentally benign production of ammonia (NH 3) products. Here, the unique effects of interfacial electric fields arising from asymmetric chemical potentials and local defects were integrated into the binary Bi 2 S 3 -Bi 2 O 3 sublattices for enhancing electrocatalytic nitrate reduction reactions. The obtained binary system showed a superior Faraday efficiency (FE) for ammonia production of 94 % and an NH 3 yield rate of 89.83 mg g cat -1h−1 at −0.4 V vs. RHE. Systematic experimental and computational results confirmed that the concerted interplay between interfacial electric fields and local defects not only promoted the accumulation and adsorption of NO 3 –, but also contributed to the destabilization of *NO and the subsequent deoxygenation hydrogenation reaction. This work will stimulate future designs of heterostructured catalysts for efficient electrocatalytic nitrate reduction reactions. [ABSTRACT FROM AUTHOR]

The conversion of fatty acids into bio-hydrocarbons can be carried out through a deoxygenation (DO) reaction. Catalytic deoxygenation of fatty acids can occur through three reaction pathways: decarbonylation, decarboxylation, and hydrodeoxygenation. In this study, three kinds of silica were prepared: (i) silica obtained from the rice husk ash (RHA); (ii) synthetic mesoporous silica SBA-16; and (iii) commercial silica. All prepared silica was used as supported nickel (Ni) catalyst for bio-hydrocarbon production through DO reaction of oleic acid. The objective of this study was to investigate the effect of variations of silica on the reaction pathway and final products composition of DO reaction of oleic acid. The catalysts were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), surface area analysis, and NH3-temperature-programme desorption. Based on XRF and XRD analysis results, it can be concluded that nickel was successfully impregnated into all silica. All samples of catalysts were used in a reaction carried out at temperature of 285 °C under a pressure of 40 bar H2 for 2h. The results showed that all catalysts were able to convert oleic acid to bio-hydrocarbon with differences in products composition. The highest oleic acid conversion of 98.25% was achieved with Ni/RHA catalyst but the obtained liquid products was the lowest among other catalysts. It is found that this phenomenon was closely related to the acidity properties of the catalyst.

There is a strong relationship between metazoan body size and extinction risk. However, the size selectivity and underlying mechanisms in foraminifera, a common marine protozoa, remain controversial. Here, we found that foraminifera exhibit size-dependent extinction selectivity, favoring larger groups (>7.4 log10 cubic micrometer) over smaller ones. Foraminifera showed significant size selectivity in the Guadalupian-Lopingian, Permian-Triassic, and Cretaceous-Paleogene extinctions where the proportion of large genera exceeded 50%. Conversely, in extinctions where the proportion of large genera was <45%, foraminifera displayed no selectivity. As most of these extinctions coincided with oceanic anoxic events, we conducted simulations to assess the effects of ocean deoxygenation on foraminifera. Our results indicate that under suboxic conditions, oxygen fails to diffuse into the cell center of large foraminifera. Consequently, we propose a hypothesis to explain size distribution-related selectivity and Lilliput effect in animals relying on diffusion for oxygen during past and future ocean deoxygenation, i.e., oxygen diffusion distance in body. [ABSTRACT FROM AUTHOR]

Controlling the cross‐coupling reaction between two different radicals is a long‐standing challenge due to the process occurring statistically, which would lead to three products, including two homocoupling products and one cross‐coupling product. Generally, the cross‐coupling selectivity is achieved by the persistent radical effect (PRE) that requires the presence of a persistent radical and a transient radical, thus resulting in limited radical precursors. In this paper, a highly selective cross‐coupling of alkyl radicals with acyl radicals to construct C(sp2)−C(sp3) bonds, or with alkyl radicals to construct C(sp3)−C(sp3) bonds have been achieved with the readily available carboxylic acids and their derivatives (NHPI ester) as coupling partners. The success originates from the use of tridentate ligand (2,2′ : 6′,2′′‐terpyridine) to enable radical cross‐coupling process to Ni‐mediated organometallic mechanism. This protocol offers a facile and flexible access to structurally diverse ketones (up to 90 % yield), and also a new solution for the challenging double decarboxylative C(sp3)−C(sp3) coupling. The broad utility and functional group tolerance are further illustrated by the late‐stage functionalization of natural‐occurring carboxylic acids and drugs. [ABSTRACT FROM AUTHOR]

Electrochemically reducing nitrate (NO3−), a common water pollutant, to valuable ammonia (NH3) offers a green, sustainable, and decentralized route for ammonia synthesis. Electrochemical nitrate reduction reaction (NO3−RR) involves two crucial reaction steps: nitrate deoxygenation followed by nitrite hydrogenation; in particular, the nitrite hydrogenation reaction is the rate‐determining step (RDS) for NO3−RR. In this work, an atomically dispersed cobalt‐phosphorus (Co─P) catalytic pair (CP) with strong electronic coupling is reported. The Co site in Co─P CP effectively activates NO3−, while the P site in Co─P CP facilitates water dissociation to release H+, synergistically enhancing the thermodynamic and kinetic performance of electrochemical nitrate reduction to ammonia. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the effects of exercise training (ET) and inspiratory muscle-loaded exercise training (IMLET) on ventilatory response and intercostal muscle deoxygenation levels during incremental cycling exercise. Methods: Twenty-one male participants were randomly divided into IMLET (n = 10) or ET (n = 11) groups. All participants underwent a 4-week cycling exercise training at 60% peak oxygen uptake. IMLET loaded 50% of maximal inspiratory pressure (PImax). Respiratory muscle strength test, respiratory muscle endurance test (RMET), resting hypoxic ventilatory responsiveness (HVR) test, and incremental cycling test were performed pre- and post-training. Results: The extent of improvement in the PImax was significantly greater in the IMLET group (24%) than in the ET group (8%) (p = .018), and an extended RMET time was observed in the IMLET group (p < .001). Minute ventilation (${\dot V_E}$V˙E) during exercise was unchanged in both groups before and after training, but tidal volume during exercise increased in the IMLET group. The increase in the exercise intensity threshold for muscle deoxygenation was similar in both groups (p < .001). HVR remained unchanged in both groups post-training. The exercise duration for the incremental exercise until reaching fatigue increased by 7.9% after ET and 6.9% after IMLET (p < .001). Conclusion: The 4-week IMLET improved respiratory muscle strength and endurance but did not alter HVR. Respiratory muscle deoxygenation was alleviated by exercise training, with a limited impact of inspiratory load training. [ABSTRACT FROM AUTHOR]

The significance and challenges of hydrotreatment processes for vegetable oils have recently become apparent, encompassing various reactions like decarbonylation, decarboxylation, and hydrogenation. Heterogeneous noble or transition metal catalysts play a crucial role in these reactions, offering high selectivity in removing oxygen and yielding desired hydrocarbons. Notably, both sulphided and non-sulphided catalysts exhibit effectiveness, with the latter gaining attention due to health and toxicity concerns associated with sulphiding agents. Nickel-based catalysts, such as NiP and NiC, demonstrate specific properties and tendencies in deoxygenation reactions, while palladium supported on activated carbon catalysts shows superior activity in hydrodeoxygenation. Comparisons between the performances of different catalysts in various hydrotreatment processes underscore the need for tailored approaches. Transition metal phosphides (TMP) emerge as promising catalysts due to their cost-effectiveness and environmental friendliness. Ultimately, there is an ongoing pursuit of efficient catalysts and the importance of further advancements in catalysis for the future of vegetable oil hydrotreatment. [ABSTRACT FROM AUTHOR]

Herein, we describe a metal‐free methodology using Selectfluor with disulfane, for the deoxygenation of N‐heterocyclic N‐oxides (33 examples). This effective, robust, and simple methodology enables the synthesis of various deoxygenated analogues from a wide range of N‐heterocyclic N‐oxide cores at room temperature in short reaction times with quantitative yields. [ABSTRACT FROM AUTHOR]

Liquid fuel production from biomass-derived molecules has received great attention due to the diminished fossil fuel reserves, growing energy demand, and the necessity of CO2 emission reduction. The deoxygenation of oils and fatty acids is a promising process to obtain "green" diesel. Herein, we report the results of the study of the deoxygenation of stearic acid to alkanes as a model reaction. Series of Ni-supported on schungite were obtained by precipitation in subcritical water (hydrothermal deposition) and for comparison via wetness impregnation followed, in both cases, by calcination at 500 °C and a reduction in H2 at 300 °C. The catalyst obtained via hydrothermal synthesis showed a three-fold higher specific surface area with a four-fold higher active phase dispersion compared to the catalysts synthesized via conventional impregnation. The catalysts were tested in stearic acid deoxygenation in supercritical n-hexane as the solvent. Under optimized process conditions (temperature of 280 °C, hydrogen partial pressure of 1.5 MPa, and 13.2 mol of stearic acid per mol of Ni), a close to 100% yield of C10–C18 alkanes, containing over 70 wt.% of targeted n-heptadecane, was obtained after 60 min of reaction. [ABSTRACT FROM AUTHOR]

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The Arabian Sea (AS) hosts the world's thickest and most intense oxygen minimum zone (OMZ), and previous studies have documented a dramatic decline of dissolved oxygen (DO) in the northeastern AS in recent decades. In this study, using the recently released data from Biogeochemical‐Argo floats, we found a surprising trend of recovery in deoxygenation within the core region of the OMZ in the AS (ASOMZ) since 2013. The average DO concentration increased by approximately threefold, from ∼0.63 μM in 2013 to ∼1.68 μM in 2022, and the thickness of the ASOMZ decreased by 13%. We find that the weakening of Oman upwelling resulting from the weakening of the summer monsoon is the main driver of oxygenation in the ASOMZ. In addition, the reduction of primary production linked to warming‐driven stratification reinforces deoxygenation recovery at depth. Plain Language Summary: The deoxygenation of the ocean is one of the most important changes occurring in the marine environment, impacting marine biodiversity, primary production, and carbon and nitrogen biogeochemical cycles. Ocean deoxygenation can cause the expansion of naturally occurring low dissolved oxygen (DO) water bodies known as OMZs. As the world's thickest and most intense oxygen minimum zone (OMZ), the Arabian Sea (AS) has undergone a dramatic decrease in DO, particularly in the northeastern AS in recent decades. Based on an unprecedented collection of DO from biogechemical‐Argo floats over the past decade, we found a surprising trend of recovery in deoxygenation within the core region of the OMZ in the AS (ASOMZ) since 2013. The average DO concentration in the ASOMZ increased by almost thrice, and the thickness decreased by 13%. Weakening of the summer monsoon over the AS and strengthening of stratification induced by global warming are possible causes for the recovery from deoxygenation. OMZs have major impacts on global carbon and nitrogen cycles. Our findings not only overturn the previous view of the deoxygenation trend in the ASOMZ but also provide valuable insights for projection model studies of global OMZs. Key Points: Deoxygenation in the oxygen minimum zone in the Arabian Sea has been recovered during the past decadeThe decrease in Oman upwelling due to the weakening of the summer monsoon is likely the main mechanism for the increase in dissolved oxygenThe strengthening of stratification in the AS leading to a decrease in production also contributed to the recovery of deoxygenation [ABSTRACT FROM AUTHOR]

Herein, we describe a general hydrodefunctionalization protocol of alcohols and amines through a common isonitrile intermediate. To cleave the relatively inert C−NC bond, we leveraged dual hydrogen atom transfer (HAT) and photoredox catalysis to generate a nucleophilic boryl radical, which readily forms an imidoyl radical intermediate from the isonitrile. Rapid β‐scission then accomplishes defunctionalization. This method has been applied to the hydrodefunctionalization of both amine and alcohol‐containing pharmaceuticals, natural products, and biomolecules. We extended this approach to the reduction of carbonyls and olefins to their saturated counterparts, as well as the hydrodecyanation of alkyl nitriles. Both experimental and computational studies demonstrate a facile β‐scission of the imidoyl radical, and reconcile differences in reactivity between nitriles and isonitriles within our protocol. [ABSTRACT FROM AUTHOR]

Topotactic phase transitions induced by changes in the oxygen vacancy concentration can largely alter the physical properties of complex oxides, including electronic and magnetic phases, while maintaining the structural integrity of the crystal lattice. An oxygen‐vacancy‐induced topotactic phase transition from perovskite (PV) to brownmillerite (BM) is achieved in epitaxial La0.6Sr0.4CoO3−δ (LSCO) thin films. Two novel intermediate states with different oxygen content are identified by X‐ray diffraction, which involves a single‐phase reduced PV state and a mixed state of co‐existing PV and BM. The combination of depth‐sensitive polarized neutron reflectometry (PNR) and Rutherford backscattering (RBS) allows a quantitative determination of magnetization and the mean oxygen content in all states, revealing a continuous transition from La0.6Sr0.4CoO2.97 to La0.6Sr0.4CoO2.5. BM formation is observed for an LSCO layer with an oxygen content of 2.67, while the magnetic and electronic transition already occurs for a layer with a higher oxygen content of 2.77 (and above) and in the absence of a BM signature. These results demonstrate that the physics of electronic metal‐to‐insulator transition (MIT), magnetic ferromagnet‐to‐non‐ferromagnet transition (FM‐to‐non‐FM), and structural PV‐to‐BM phase transition should be considered within the framework of separate but interrelated processes. [ABSTRACT FROM AUTHOR]

We present a novel deoxygenation method for heterocyclic Noxides utilizing iodide as a catalyst. Iodide acts as a reducing catalyst that is regenerated by formic acid, which also serves as a Brønsted activator and solvent. The method demonstrates high efficiency and excellent selectivity in the reduction of a variety of heterocyclic N-oxides and tertiary amines. Our computational DFT investigation revealed that the reduction mechanism entails a direct interaction between iodide and the oxygen of the N-oxide within a Mg2+/formic acid framework, resulting in the formation of the N-heterocycle and the release of a hypoiodite unit. Additionally, a molecular mechanism for the regeneration of iodide from hypoiodite, facilitated by formic acid, is suggested. This method provides an environmentally friendly approach for the deoxygenation of N-oxides and related species. [ABSTRACT FROM AUTHOR]

Regio‐ and chemo‐selective functionalization of electron deficient azaarenes often required their transformations to corresponding N‐oxides and subsequent removal of oxygen after functionalization to get back the desired substituted azaarenes. An efficient metal‐free visible‐light photo‐redox catalytic deoxygenation of N‐oxides of azaheterocyclic compounds has been developed using acridinium based organo‐photocatalyst in blue LED light. High efficiency and mildness of this methodology has been demonstrated through higher deoxygenation yield of wide variety of azaheterocyclic N‐oxides with reactive functional groups. Robustness of the photocatalytic reduction has been demonstrated through easy scaling‐up of the reaction to gram level without much change in the reaction yield. [ABSTRACT FROM AUTHOR]

Catalytic defunctionalization of complex molecules has attracted significant attention in organic synthesis. This reaction enables common functional groups to serve as "traceless handles" for the new bond construction. In this mini-review, we have summarized the latest advances, methodologies and mechanistic insights into the selective cleavage of C-C and C-X bonds catalysed by cobalt complexes, shedding light on their increasing importance in modern chemical synthesis. The content of this review is categorized according to the type of functional group being removed from molecules. [ABSTRACT FROM AUTHOR]

The hydrogenation reaction of guaiacol in the gas phase at 300 °C and atmospheric pressure of hydrogen was investigated over Ni-based catalysts supported on niobium oxide (Nb2O5) and exfoliated potassium hexaniobate (Nb-exf). The catalysts were prepared by two different methods: photodeposition (pd) and incipient wetness impregnation (im) and were characterized by N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption of ammonia (NH3-TPD) analyses. XRD analysis showed that all catalysts exhibited approximately the same crystallite size of the metallic nickel (15 nm). Regarding the catalytic tests, guaiacol was mainly converted to catechol (59.5–80.6%) and phenol (4.4–14.2%) regardless of the catalyst. Small amounts of benzene were only observed over Ni(im)/Nb2O5. The catalytic experiments showed that the main reaction pathway is the conversion of guaiacol through demethylation reaction producing catechol followed by phenol formation via dehydroxylation reaction. Ni(im)/Nb2O5 was tested for catalytic upgrading of pyrolysis vapor of different biomasses (lignin, microalgae, and malt residue), and it was able to reduce the yield of oxygenated products. The catalytic upgrading of pyrolysis vapor of microalgae using a catalyst-to-biomass weight ratio (C:B) of 3:1 showed the highest selectivity of hydrocarbons (57.44%). The catalyst concentration and the biomass used in the test showed a high influence on the product distribution. [ABSTRACT FROM AUTHOR]

A novel strategy for the chemoselective conversion of sulfoxides to sulfide utilizing D-camphorsulfonic acid (D-CSA) as a reducing reagent has been developed under metal and additive-free conditions. A variety of sulfoxides such as alkyl–aryl, allyl–aryl, benzyl–aryl, aryl–ethyl sulfoxides have been effectively utilized to achieve the corresponding reduced products in good to excellent yields under mild conditions without any additive. The proposed method offers a practical solution for the deoxygenation of sulfoxides, which has potential applications in various fields such as pharmaceuticals, materials science, and organic synthesis. A novel strategy for the chemoselective deoxygenation of diverse sulfoxides without metal and additive has been disclosed using D-camphorsulfonic acid (D-CSA) as the reducing agent. The reaction proceeds under mild conditions to afford the sulphides in moderate to good yields with great tolerance of diverse functional groups. [ABSTRACT FROM AUTHOR]

Respiratory activity in the oceans is declining due to the expansion of hypoxic zones and progressive deoxygenation, posing threats to marine organisms along with impacts of concurrent ocean acidification. Therefore, understanding the combined impacts of reduced pO2 and elevated pCO2 on marine primary producers is of considerable significance. Here, to simulate diatoms’ sinking into the aphotic zone of turbid coastal water, we exposed the diatoms Thalassiosira pseudonana and Thalassiosira weissflogii in darkness at 20°C to different levels of pO2 and pCO2 conditions for ~3 weeks, and monitored their biomass density, photosynthetic activity and dark respiration, and examined their recovery upon subsequent exposure to light at 20°C, simulating surface water conditions. Along with decreased cell abundance and size, measured photosynthetic capacity and dark respiration rates in these two diatoms both gradually decreased during the prolonged darkness. Reduced pO2 alone did not negatively affect the photosynthetic machinery in both the dark-survived diatom, and enhanced their subsequent recovery upon light exposure. Nevertheless, the combination of the elevated pCO2 and reduced pO2 (equivalent to hypoxia) led to the biomass loss by about 90% in T. pseudonana, and delayed the recovery of both species upon subsequent exposure to light, though it did not reduce the cell concentration of T. weissflogii during the elongated darkness. Our results suggest that reduced O2 availability diminishes the abilities of the diatoms to cope with the acidic stress associated with ocean acidification, and the expansion of hypoxic waters could delay the photosynthetic recovery of coastal diatoms when they are transported upwards through mixing from dark layers to sunlit waters. [ABSTRACT FROM AUTHOR]

In this study, the relationship between dissolved oxygen reduction in the Gulf of Oman and changes in effective factors such as temperature and thermal stratification, exchanges with nearby water bodies, biological activities, chlorophyll-a concentration, and primary production was studied. The data used in this research were extracted from the measurement data available on global sites such as the World Ocean Atlas and SeaWiFS and MODIS satellite images. Comparing the average annual DO profiles in the Gulf of Oman showed a decrease in the upper 1000 m layer in 2010 compared to 1960. The DO reduction in the surface mixed layer was 0.4 mg/l and reached 3.7 mg/l at 100 m depth. At depths more than 100 m, the amount of change decreased and reached 0.1 mg/l at 1000 m. Due to the deoxygenation, the thickness of the surface layer with DO˃2 mg/l decreased from 150 m to 80 m. The results demonstrated that the drop in DO in the surface mixed layer was consistent with the decrease in gas solubility caused by the temperature increment in this layer. Regarding the severe reduction of DO in the layer below the surface mixed layer, it was shown that the strengthening of thermal vertical stratification and intensification of thermocline (0.01°C/m increase in thermal gradient) were the most important factors. [ABSTRACT FROM AUTHOR]

The study describes a concise four‐step formal total synthesis of racemic (±)‐laurokamurene B, a sesquiterpene with a rearranged laurene carbon framework. This method also extends to the formal total synthesis of β‐cuparenone. Compared with previously reported laurokamurene B's syntheses, our approach significantly reduces the total number of reaction steps by leveraging the known scaffolds as the key concept. Optimized esterification for the generation of appropriately substituted cinnamate esters, one‐pot polyphosphoric acid (PPA) mediated fragmentation followed by Friedel–Crafts acylation, and intramolecular cyclization led to the efficient construction of pivotal intermediate 3‐arylcyclopent‐2‐en‐1‐one with a quaternary center; subsequent α‐methylation and reductive deoxygenation resulted into the marine natural product (±)‐laurokamurene B. Additionally, β‐methylation and deoxygenation of the obtained key 3‐arylcyclopente‐2‐en‐1‐one intermediate could also serve for the formal total synthesis of (±)‐β‐cuparenone in the shortest approach. [ABSTRACT FROM AUTHOR]

20CrMnTi steel is widely used in the gear manufacturing field of engineering machinery. The addition of Ti element to steel can effectively improve its low-temperature impact toughness and enhance its mechanical properties. However, during the smelting process of 20CrMnTi, large-sized TiN inclusions are inevitably formed in the steel, which affects its service performance improvement. This paper focuses on the directional modification behaviors of TiN inclusions in 20CrMnTi gear steel by rare earth Ce under deoxygenation conditions of Si–Ca–Ba alloy. The results show that under the deoxygenation conditions of Si–Ca–Ba alone, there are composite inclusions in 20CrMnTi steel with CaAl12O19 as the core and TiN wrapped around the periphery, all of which have sizes greater than 2 μm. This type of inclusion is square or diamond shaped, and the addition of Si–Ca–Ba deoxygenation alone has poor TiN modification effect on gear steel 20CrMnTi. Adding Ce element can effectively improve the nucleation core of inclusions. The CeAlO3–TiN and (CaAl12O19–Ba–Ce)–TiN composite inclusions are formed, and the TiN inclusions are modified in terms of morphology and size. The average size of inclusions decreases from 4.1 to 3.0 μm, which prevented the excessive growth of pure TiN inclusions to some extent.

Abstract A key control on the magnitude of coastal eutrophication is the degree to which currents quickly transport nitrogen derived from human sources away from the coast to the open ocean before eutrophication develops. In the Southern California Bight (SCB), an upwelling-dominated eastern boundary current ecosystem, anthropogenic nitrogen inputs increase algal productivity and cause subsurface acidification and oxygen (O $$_{2}$$ 2 ) loss along the coast. However, the extent of anthropogenic influence on eutrophication beyond the coastal band, and the physical transport mechanisms and biogeochemical processes responsible for these effects are still poorly understood. Here, we use a submesoscale-resolving numerical model to document the detailed biogeochemical mass balance of nitrogen, carbon and oxygen, their physical transport, and effects on offshore habitats. Despite management of terrestrial nutrients that has occurred in the region over the last 20 years, coastal eutrophication continues to persist. The input of anthropogenic nutrients promote an increase in productivity, remineralization and respiration offshore, with recurrent O $$_{2}$$ 2 loss and pH decline in a region located 30–90 km from the mainland. During 2013 to 2017, the spatially averaged 5-year loss rate across the Bight was 1.3 mmol m $$^{-3}$$ - 3 O $$_{2}$$ 2 , with some locations losing on average up to 14.2 mmol m $$^{-3}$$ - 3 O $$_{2}$$ 2 . The magnitude of loss is greater than model uncertainty assessed from data-model comparisons and from quantification of intrinsic variability. This phenomenon persists for 4 to 6 months of the year over an area of 27,840 km $$^{2}$$ 2 ( $$\sim$$ ∼ 30% of SCB area). These recurrent features of acidification and oxygen loss are associated with cross-shore transport of nutrients by eddies and plankton biomass and their accumulation and retention within persistent eddies offshore within the SCB.

Due largely to the high stability and the potential ozone‐depleting, the transformation of greenhouse gas nitrous oxide has gained much attentions. In present paper, a new insight into the deoxygenation of nitrous oxide with silane was reported by using oriented external electric field (OEEF) as a catalytic strategy. When the OEEF was employed, the reaction barrier of deoxygenation was marvelously decreased as it was oriented along the positive NO/OSi bond‐axis. Especially the field strength is 300 × 10−4 a.u., the differences are up to 22.4/18.3 kcal mol−1 as compared with that of nonfield. In addition, once the H atom in SiH4 was replaced by methyl, two reaction modes were obtained, in which the deoxygenation process was easier when the N2O captured the H atom attached to the Si atom, not attached to the C atom. Further, the solvent effects of deoxygenation reaction were also considered, but with a weak influence were obtained. [ABSTRACT FROM AUTHOR]