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The oxygen isotope composition of phosphate is a useful tool for studying biogeochemical phosphorus cycling. However, the current Ag3PO4method is not only tedious in PO43–extraction and purification but also requires a large-sized sample at the micromole level, thereby limiting its application. Here, we present an approach to measuring the oxygen isotope composition, δ18O, of dissolved phosphate at the nanomole level using electrospray ionization Orbitrap mass spectrometry (ESI-Orbitrap-MS). We compared the reproducibility of δ18O measurements using the H2PO4–ions (m/z= 97 and 99 for H2P16O4–and H2P18O16O3–, respectively) and using the PO3–fragment ions (m/z= 79 and 81 for P16O3–and P18O16O2–, respectively) generated by source fragmentation and by higher-energy collisional dissociation, respectively. The results demonstrate that phosphate δ18O can be more reliably measured by the PO3–ions than by the H2PO4–ions. PO3–generated by source fragmentation at 40 V achieved the highest reproducibility for δ18O based on precision tests. Furthermore, the mass spectrum for a 50:50 μM mixed solution of phosphate and sulfate revealed that PO3–ions resulting from source fragmentation at 40 V are the predominant species in the Orbitrap analyzer. Notably, P16O3–ions (m/z: 79) are not interfered with by 32S16O3–(m/z: 80) ions. This is in contrast to the case for 1H2P16O4–ions, which share the same m/zvalue with 1H32S16O4–ions and exhibit much lower signal intensity than HSO4–ions. Using the PO3–fragment method and six phosphate standards with a wide range of δ18O values, we obtained a calibration line with a slope of 0.94 (R2= 0.98). The overall uncertainty for ESI-Orbitrap-MS phosphate δ18O measurement was 0.8‰ (n= 30; 1 SD). With much room for improvement, the PO3–fragment method presents a better approach to measuring the phosphate oxygen isotope composition, applicable to nanomole sample sizes in a liquid phase.

Sulfate aerosols affect climate by scattering radiation and by changing the microphysical properties of water clouds. In much of the continental interiors that are overwhelmed by anthropogenic sulfate today, the nature of pre-industrial atmospheric sulfate remains pure speculation, which hampers our ability to quantify anthropogenic perturbation on climate and uncertainties in global climate models. Here we show that sequential leaching and multiple-isotope measurement enabled us to effectively distinguish sulfate of different origins, including pre-industrial atmospheric sulfate, retained in certain outcropping carbonates. Data from two interior sites in northern China show that one of the sulfate endmembers consistently has an unusually positive 17O anomaly (Δʹ17O at ~+1.8‰) and characteristic δ18O (~1–5‰) and δ34S (~5–10‰) values. We interpret this sulfate endmember to be integrated pre-industrial atmospheric sulfate from at least the last a few thousands of years. A triple oxygen isotope enabled GEOS-Chem chemical transport model revealed a higher Δʹ17O value in northern China and the south-western United States in the past, consistent with our data. Overall, pre-industrial atmospheric sulfate aerosol chemistry in the interior of northern China and south-western United States had a higher pH in cloud water, which may have led to a less cloud cover due to cleaner air and coarser aerosol sizes than today.

A synthesis of global barite sulfate isotope data from approximately 635 million years ago, at the end of a global glaciation, undermines the hypothesis that river sulfate was the primary carrier of the distinctive 17O-depleted atmospheric O2 signature of the time. Instead, an aqueous H2S oxidation model on the shelf emerges as a compelling alternative, though it demands extensive validation across multiple fronts by the scientific community.

The proposed “ligands hybridization” strategy and the application of novel MOF-based catalysts in OER were introduced. The OER mechanism highlights the importance of Ni doping effect.

Both nanocrystals and carbon materials have attracted considerable attention in lithium-ion batteries (LIBs) because of their fast kinetics for lithium storage or long-life cycles. However, the easy aggregation of nanocrystals and high-temperature doping process of carbon materials seriously hindered their application in LIBs. Here, we report the development of unprecedented TiO2–x@C nanocomposite electrodes through a unique “melting low-temperature pyrolysis” strategy. It is found that the continuous and interconnected three-dimensional amorphous carbon frameworks (3DCFs) in the composites are closely connected with TiO2nanocrystals by Ti–O–C covalent bonding, forming robust 3D framework architectures. Interestingly, we find that TiO2nanocrystals can greatly improve the pseudocapacitance of TiO2–x@C nanocomposite electrodes with increasing cycles, which significantly exceeds previously reported TiO2-based anodes and carbon materials. Furthermore, for the first time, the unusual improvement of pseudocapacitance of TiO2–x@C electrodes is carefully investigated by means of dQ/dVcurves and electrochemical kinetic analysis to reveal the extra contribution of lithium storage. 3DCF, a “lithium-ion reservoir”, possesses an unexpected capacity enhancement behavior that is triggered by TiO2nanocrystals and exhibits bicontinuous pathways for both rapid ion and electron transport. In this case, TiO2nanocrystals stabilizing the 3DCF acted as a conductive agent during charge and discharge. Our findings confirm that the 3DCF triggered by TiO2nanocrystals boosted the electrochemical performance of TiO2–x@C nanocomposite electrodes, especially the pseudocapacitance enhancement. The unique characteristics of ingenious combination of TiO2nanocrystals and amorphous carbon materials make them attain superior electrochemical properties in all known TiO2- and carbon-based anodes (289 mA h g–1at 5 A g–1after 4000 cycles). Above all, our findings reveal previously ignored fundamental aspects of pseudocapacitance improvement of nanocomposite electrodes and offer new hope for structural design and carbon coating process of high-performance anode materials.

Marinoan snowball Earth offers us a set of sedimentary and geochemical records for exploring glacial isostatic adjustment (GIA) associated with one of the most severe glaciations in Earth history. An accurate prediction of GIA‐based relative sea level (RSL) change associated with a snowball Earth meltdown will help to explore sedimentary records for RSL changes and to place independent constraints on mantle viscosity and on the durations of syndeglaciation (Td) and cap carbonate deposition. Here we mainly examine postdeglacial RSL change characterized by an RSL drop and a resumed transgression inferred from the cap dolostones on the continental shelf in south China. Such a nonmonotonic RSL behavior may be a diagnostic GIA signal for the Marinoan deglaciation resulting from a significantly longer postdeglacial GIA response than that for the last deglaciation. A postdeglacial RSL drop followed by transgression in south China, which is significantly affected by Earth's rotation, is predicted over the continental shelf for models with Td≤ 20 kyr and a deep mantle viscosity of ~5 × 1022Pa s regardless of the upper mantle viscosity. The inferred GIA model also explains the postdeglacial RSL changes such as sedimentary‐inferred RSL drops on the continental shelf in northwestern Canada and California at low‐latitude regions insignificantly affected by Earth's rotation. Furthermore, the good match between the predicted and observed RSL changes in south China suggests an approximate duration of ~50 kyr for the Marinoan 17O depletion event, an atmospheric event linked to the post‐Marinoan drawdown of CO2and the concurrent rise of O2. Nonmonotonic postdeglacial RSL changes for the Marinoan deglaciation are examined to infer the syndeglacial duration and mantle viscosityGIA model with a syndeglacial duration of <20 kyr and a deep mantle viscosity of ~5 × 1022Pa s explains sedimentary‐inferred RSL recordsPredicted and observed RSL changes in south China suggest an approximate duration of ~50 kyr for the Marinoan 17O depletion (MOSD) event

The global biosphere is commonly assumed to have been less productive before the rise of complex eukaryotic ecosystems than it is today1. However, direct evidence for this assertion is lacking. Here we present triple oxygen isotope measurements (∆17O) from sedimentary sulfates from the Sibley basin (Ontario, Canada) dated to about 1.4 billion years ago, which provide evidence for a less productive biosphere in the middle of the Proterozoic eon. We report what are, to our knowledge, the most-negative ∆17O values (down to −0.88‰) observed in sulfates, except for those from the terminal Cryogenian period2. This observation demonstrates that the mid-Proterozoic atmosphere was distinct from what persisted over approximately the past 0.5 billion years, directly reflecting a unique interplay among the atmospheric partial pressures of CO2and O2and the photosynthetic O2flux at this time3. Oxygenic gross primary productivity is stoichiometrically related to the photosynthetic O2flux to the atmosphere. Under current estimates of mid-Proterozoic atmospheric partial pressure of CO2(2–30 times that of pre-anthropogenic levels), our modelling indicates that gross primary productivity was between about 6% and 41% of pre-anthropogenic levels if atmospheric O2was between 0.1–1% or 1–10% of pre-anthropogenic levels, respectively. When compared to estimates of Archaean4–6and Phanerozoic primary production7, these model solutions show that an increasingly more productive biosphere accompanied the broad secular pattern of increasing atmospheric O2over geologic time8. Triple oxygen isotope measurements of 1.4-billion-year-old sedimentary sulfates reveal a unique mid-Proterozoic atmosphere and demonstrate that gross primary productivity in the mid-Proterozoic was between 6% and 41% of pre-anthropogenic levels.

Riverine dissolved sulfate (SO42–) sulfur and oxygen isotope variations reflect their controls such as SO42–reduction and reoxidation, and source mixing. However, unconstrained temporal variability of riverine SO42–isotope compositions due to short sampling durations may lead to mischaracterization of SO42–sources, particularly for the pyrite-derived sulfate load. We measured the sulfur and triple-oxygen isotopes (δ34S, δ18O, and Δ′17O) of Mississippi River SO42–with biweekly sampling between 2009 and 2013 to test isotopic variability and constrain sources. Sulfate δ34S and δ18O ranged from −6.3‰ to −0.2‰ and −3.6‰ to +8.8‰, respectively. Our sampling period captured the most severe flooding and drought in the Mississippi River basin since 1927 and 1956, respectively, and a first year of sampling that was unrepresentative of long-term average SO42–. The δ34SSO4data indicate pyrite-derived SO42–sources are 74 ± 10% of the Mississippi River sulfate budget. Furthermore, pyrite oxidation is implicated as the dominant process supplying SO42–to the Mississippi River, whereas the Δ′17OSO4data shows 18 ± 9% of oxygen in this sulfate is sourced from air O2.

Geodynamic processes on early Earth, especially the interaction between the crust and deep mantle, are poorly constrained and subject to much debate. The rarity of fresh igneous materials more than 3 billion years old accounts for much of this uncertainty. Here we examine 3.27-billion-year-old komatiite lavas from Weltevreden Formation in the Barberton greenstone belt, which is part of the Kaapvaal Craton in Southern Africa. We show that primary magmatic compositions of olivine are well preserved in these lavas based on major and trace element systematics. These komatiitic lavas represent products of deep mantle plumes. Oxygen isotope compositions (δ18O) of the fresh olivine measured by laser fluorination are consistently lighter (about 2‰) than those obtained from modern mantle-derived volcanic rocks. These results suggest a mantle source for the Weltevreden komatiites that is unlike the modern mantle and one that reflects mantle heterogeneity left over from a Hadean magma ocean. The anomalously light δ18O may have resulted from fractionation of deep magma ocean phases, as has been proposed to explain lithophile and siderophile isotope compositions of Archaean komatiites.

Two global glaciations occurred during the Neoproterozoic. Snowball Earth theory posits that these were terminated after millions of years of frigidity when initial warming from rising atmospheric CO2concentrations was amplified by the reduction of ice cover and hence a reduction in planetary albedo. This scenario implies that most of the geological record of ice cover was deposited in a brief period of melt-back. However, deposits in low palaeo-latitudes show evidence of glacial–interglacial cycles. Here we analyse the sedimentology and oxygen and sulphur isotopic signatures of Marinoan Snowball glaciation deposits from Svalbard, in the Norwegian High Arctic. The deposits preserve a record of oscillations in glacier extent and hydrologic conditions under uniformly high atmospheric CO2concentrations. We use simulations from a coupled three-dimensional ice sheet and atmospheric general circulation model to show that such oscillations can be explained by orbital forcing in the late stages of a Snowball glaciation. The simulations suggest that while atmospheric CO2concentrations were rising, but not yet at the threshold required for complete melt-back, the ice sheets would have been sensitive to orbital forcing. We conclude that a similar dynamic can potentially explain the complex successions observed at other localities.

In hydraulic area, independent metering control (IMC) technology is an effective approach to improve system efficiency and control flexibility. In addition, digital hydraulic technology (DHT) has been verified as a reasonable method to optimize system dynamic performance. Integrating these two technologies into one component can combine their advantages together. However, few works focused on it. In this paper, a twin spools valve with switching technology-controlled pilot stage (TSVSP) is presented, which applied DHT into its pilot stage while appending IMC into its main stage. Based on this prototype valve, a series of numerical and experiment analysis of its IMC performance with both simulated load and excavator boom cylinder are carried out. Results showed fast and robust performance of pressure and flow compound control with acceptable fluctuation phenomenon caused by switching technology. Rising time of flow response in excavator cylinder can be controlled within 200 ms, meanwhile, the recovery time of rod chamber pressure under suddenly changed condition is optimized within 250 ms. IMC system based on TSVSP can improve both dynamic performance and robust characteristics of the target actuator so it is practical in valve-cylinder system and can be applied in mobile machineries.

Silicate melts have served as transport agents in the chemical and thermal evolution of Earth. Molecular dynamics simulations based on a deep neural network potential trained by ab initiodata show that the viscosity of MgSiO3melt decreases with increasing pressure at low pressures (up to ∼6 GPa) before it starts to increase with further compression. The melt electrical conductivity also behaves anomalously; first increasing and then decreasing with pressure. The melt accumulation implied by the viscosity turnover at ∼23 GPa along mantle liquidus offers an explanation for the low‐velocity zone at the 660‐km discontinuity. The increase in electrical conductivity up to ∼50 GPa may contribute to the steep rise of Earth's electrical conductivity profiles derived from magnetotelluric observations. Our results also suggest that small fraction of melts could give rise to detectable bulk conductivity in deeper parts of the mantle. Dynamical behavior of silicate melts at high temperature and pressure controls melt distribution in Earth's interior. However, experimental data on the viscosity and electrical conductivity of silicate melts are limited to relatively low pressure. Moreover, the pressure dependence of viscosity is in debate, especially for depolymerized silicate melts. Using a new deep learning‐based simulation approach, we find that both the viscosity and electrical conductivity of MgSiO3melt behave anomalously with pressure, which could have important implications for zones with seismic velocity anomalies and high electrical conductivity in Earth's interior. The viscosity of MgSiO3melt behaves anomalously at relatively low temperatures; first decreasing and then increasing with pressureThe electrical (ionic) conductivity shows anomalous pressure behavior at all temperaturesDeep potential molecular dynamics simulations offer us a reliable and complete data set to study transport properties of silicate melts The viscosity of MgSiO3melt behaves anomalously at relatively low temperatures; first decreasing and then increasing with pressure The electrical (ionic) conductivity shows anomalous pressure behavior at all temperatures Deep potential molecular dynamics simulations offer us a reliable and complete data set to study transport properties of silicate melts

In this paper, the corrosion resistance test of sisal fiber-reinforced concrete under simulated marine environment is carried out, and the corrosion resistance of sisal fiber-reinforced concrete is predicted by using grey theory and Verhulst model. The results show that sisal fiber can effectively improve the strength of concrete under the corrosion of marine environment. With the increase in sisal fiber content, the compressive strength of concrete increases as a whole compared with that of concrete without sisal fiber. After 15 days of corrosion cycle, the maximum strength increase ratio of concrete with sisal fiber is 18.58. After 30 days of corrosion cycle, the maximum strength increase ratio of concrete with sisal fiber is 12.72. The GM (1,1) model and Verhulst model in grey system theory are used to simulate the mechanical properties of sisal fiber-reinforced concrete and its corrosion resistance in marine environment. The results show that the average relative residual difference between the simulated and measured values is small and belongs to the first-order accuracy. It shows that the GM (1,1) model and Verhulst model in grey system theory can be used in the mechanics of sisal fiber-reinforced concrete, and prediction and analysis of performance and corrosion resistance in marine environment. A new corrosion-resistant material may be born from it.

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