The Responses of Soil Mineral-associated Organic Carbon to Exogenous Carbon Additions: a Protocol for a Systematic Review and Meta-analysis

Background: Increased exogenous carbon inputs into soils under global climate change can induce soil organic carbon (SOC) decomposition, which has profound effects on carbon cycle and feedback on climate change. Soil mineral-associated organic carbon (MAOC) is the SOC protected from decomposition through association with minerals. Recent studies demonstrated that MAOC can be mineralized due to exogenous carbon inputs. The objective of this study is to provide the methods used to explore the effect of exogenous carbon inputs on MAOC and the controlling factors.Methods: We will search for the potential studies that evaluating the influence of carbon additions on MAOC content and decomposition through the Web of Science, Scopus and China National Knowledge Infrastructure until August 2021. If the studies searched by using keywords meet the inclusion criteria, then they were included. The STATA software (version 15.0) will be used to perform data analysis. The results include the content and decomposition intensity of MAOC induced by exogenous carbon additions and the controlling factors. Study selection, data extraction, and assessment of bias risk will be conducted by two reviewers independently. Subgroup analysis will be carried out to explore sources of heterogeneity when heterogeneity is observed. Sensitivity analysis will be used to assess the robustness of the analyses.Discussion: This study will provide useful methods for exploring the effect of carbon additions on MAOC and the controlling factors.

The influence of Cr, Al, Co, Fe and C on negative creep of Waspaloy

Negative creep using precision dilatation experiments is investigated on a broad variety of single, dual and multiphase nickel-based superalloys. Pure nickel and dilute binary nickel-based alloys show no signs of negative creep. However, with higher contents of Cr and Al and in highly alloyed ternary and multicomponent nickel-based alloys negative creep is observed. Short range ordering of Cr and/ or Al are identified to cause negative creep at 550 °C. Carbon additions leading to retarded carbide precipitation or transformation can enhance negative creep.

A new framework to quantify carbon cycle perturbations using trace metal isotopes

<p>Reconstructing the environmental consequences of large carbon additions in the past has the potential to improve our understanding and prediction of how the Earth system will respond to human carbon emissions. However, uncertainties over the scale and timing of external carbon additions during past carbon emission events limit quantitative knowledge gained from the geological record. The metals Sr, Os, Li and Ca are essential proxies for changes in volcanic activity and terrestrial weathering rates, and thus for major causes of pre-industrial carbon emission and sequestration, because their isotopic compositions in old continental crust and Earth’s mantle differ significantly. So far, box models and equilibrium-state equations have been the only method to quantitatively relate weathering-derived and magmatic input fluxes to trace metal concentrations and isotopic ratios preserved in ancient sediments. This approach results most commonly in a first order estimate of emitted carbon or weathering changes, but it does not account for the effect of climate feedbacks on metal sources and sinks and associated variations in the residence time of these metals in the ocean. Particularly during fast carbon emissions (e.g. Cenozoic hyperthermals, Oceanic Anoxic Events), the processes which added isotopically traceable metals to the oceans also enchained environmental changes which would have affected metal cycles and residence times, resulting in significant alterations of the recorded isotopic excursion in marine sediments. To disentangle the signals of causes and consequences of environmental change recorded by trace metal isotopes, we simulated various coupled carbon and metal cycle perturbations in the 3D Earth system model of intermediate complexity cGENIE, now containing the first representation of isotope-enabled trace metal dynamics. Here, we present a resulting extended framework to reconstruct metal and carbon fluxes from the geological trace metal record during periods of environmental change.</p>

Comparative Study of DC and RF Sputtered MoSe2 Coatings Containing Carbon—An Approach to Optimize Stoichiometry, Microstructure, Crystallinity and Hardness

Low stoichiometry, low crystallinity, low hardness and incongruencies involving the reported microstructure have limited the applicability of TMD-C (Transition metal dichalcogenides with carbon) solid-lubricant coatings. In this work, optimized Mo–Se–C coatings were deposited using confocal plasma magnetron sputtering to overcome the above-mentioned issues. Two different approaches were used; MoSe2 target powered by DC (direct current) or RF (radio frequency) magnetron sputtering. Carbon was always added by DC magnetron sputtering. Wavelength dispersive spectroscopy displayed Se/Mo stoichiometry of ~2, values higher than the literature. The Se/Mo ratio for RF-deposited coatings was lower than for their DC counterparts. Scanning electron microscopy showed that irrespective of the low carbon additions, the Mo–Se–C coatings were highly compact with no vestiges of columnar growth due to optimal bombardment of sputtered species. Application of substrate bias further improved compactness at the expense of lower Se/Mo ratio. X-ray diffraction, transmission electron microscopy, and Raman spectroscopy confirmed the presence of MoSe2 crystals, and (002) basal planes. Even very low carbon additions led to an improvement of the hardness of the coatings. The work reports a comparison between RF and DC sputtering of MoSe2 coatings with carbon and provides a guideline to optimize the composition, morphology, structure, and mechanical properties.

Effect of Nanocarbons Additions on the Microstructures and Properties of Copper Matrix Composite by Spray Drying Process

Novel copper-nanocarbons – Cu-fullerene soot/reduced graphene oxide composites with 0-5 wt.% carbon additions were fabricated by spray drying method and hot pressing procedure. In order to obtain the homogeneity of composites, the spray drying integrating with shear mixing was adopted. The microstructure and properties of the composite materials were investigated and compared to Cu–graphite composite, which was prepared under the standard technology. The interface, depending on the nanocarbons addition, prevents copper aggregation, and inhibits the copper grain growth. The compact composites hardness was significantly higher as compared with Cu-CNTs and Cu-Graphite composites of the same carbon concentration with small reduction of the thermal conductivity.