| 1. |
- Yadav, Jitendra Kumar, et al.
(författare)
-
Isonicotinate-Zn(ii)/Cd(ii) bridged dicobaloximes : synthesis, characterization and electrocatalytic proton reduction studies
- 2023
-
Ingår i: New Journal of Chemistry. - 1144-0546. ; 47:44, s. 20583-20593
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, we present the synthesis of two new dicobaloxime complexes, [{ClCo(dmgH)2(4-PyCOO)}2Zn(DMF)2] (1) and [{ClCo(dmgH)2(4-PyCOO)}2Cd(H2O)3(DMF)].4H2O (2) bridged by isonicotinate-Zn(ii) and Cd(ii) moieties. These complexes were synthesized upon reaction of a monomeric chlorocobaloxime [ClCo(dmgH)2(4-PyCOOH)] with Zn(NO3)2·6H2O and Cd(OAc)2·2H2O in a methanol/DMF solvent mixture. Both complexes are fully characterized by UV-Visible, FT-IR, and NMR (1H and 13C{1H}) spectral studies. The solid-state structures are also determined by single-crystal X-ray crystallography. In complex 1, Zn (ii) metal ions reside within a four coordinated distorted tetrahedral geometry (ZnO4) formed by two oxygen atoms of isonicotinate connected to cobaloxime units and two oxygen atoms of DMF molecules. In complex 2, the Cd(ii) metal ion exhibited distorted octahedral geometry (CdO6), with two oxygen atoms of isonicotinate that connect to cobaloxime units, one DMF, and three water molecules. The Co(iii) metal center of cobaloxime units in both complexes 1 and 2 displayed distorted octahedral geometry with two dmgH units in the equatorial plane whereas chloride ion (Cl−) and the nitrogen atom of isonicotinate occupy the axial coordination sites. The redox behaviour of both complexes was studied by cyclic voltammetry at variable scan rates in deoxygenated DMF/H2O (95 : 5) solution using 0.1 M TBAPF6 as the supporting electrolyte and a glassy carbon (GC) electrode as the working electrode. Both complexes exhibited similar redox properties and two redox couples CoIII/II and CoII/CoI are observed in the reductive scan. Furthermore, complexes are investigated as electrocatalysts for proton reduction in the presence of acetic acid (AcOH) and complex 1 exhibited impressive electrocatalytic activity compared to complex 2 and monomer. The stability study indicated the retention of molecular structural integrity during HER electrocatalytic experiments.
|
|
| 2. |
- Mishra, Umakant, et al.
(författare)
-
Spatial heterogeneity and environmental predictors of permafrost region soil organic carbon stocks
- 2021
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:9
-
Tidskriftsartikel (refereegranskat)abstract
- Large stocks of soil organic carbon (SOC) have accumulated in the Northern Hemisphere permafrost region, but their current amounts and future fate remain uncertain. By analyzing dataset combining >2700 soil profiles with environmental variables in a geospatial framework, we generated spatially explicit estimates of permafrost-region SOC stocks, quantified spatial heterogeneity, and identified key environmental predictors. We estimated that Pg C are stored in the top 3 m of permafrost region soils. The greatest uncertainties occurred in circumpolar toe-slope positions and in flat areas of the Tibetan region. We found that soil wetness index and elevation are the dominant topographic controllers and surface air temperature (circumpolar region) and precipitation (Tibetan region) are significant climatic controllers of SOC stocks. Our results provide first high-resolution geospatial assessment of permafrost region SOC stocks and their relationships with environmental factors, which are crucial for modeling the response of permafrost affected soils to changing climate.
|
|
| 3. |
- Tao, Feng, et al.
(författare)
-
Convergence in simulating global soil organic carbon by structurally different models after data assimilation
- 2024
-
Ingår i: Global Change Biology. - 1354-1013 .- 1365-2486. ; 30:5
-
Tidskriftsartikel (refereegranskat)abstract
- Current biogeochemical models produce carbon–climate feedback projections with large uncertainties, often attributed to their structural differences when simulating soil organic carbon (SOC) dynamics worldwide. However, choices of model parameter values that quantify the strength and represent properties of different soil carbon cycle processes could also contribute to model simulation uncertainties. Here, we demonstrate the critical role of using common observational data in reducing model uncertainty in estimates of global SOC storage. Two structurally different models featuring distinctive carbon pools, decomposition kinetics, and carbon transfer pathways simulate opposite global SOC distributions with their customary parameter values yet converge to similar results after being informed by the same global SOC database using a data assimilation approach. The converged spatial SOC simulations result from similar simulations in key model components such as carbon transfer efficiency, baseline decomposition rate, and environmental effects on carbon fluxes by these two models after data assimilation. Moreover, data assimilation results suggest equally effective simulations of SOC using models following either first-order or Michaelis–Menten kinetics at the global scale. Nevertheless, a wider range of data with high-quality control and assurance are needed to further constrain SOC dynamics simulations and reduce unconstrained parameters. New sets of data, such as microbial genomics-function relationships, may also suggest novel structures to account for in future model development. Overall, our results highlight the importance of observational data in informing model development and constraining model predictions.
|
|
| 4. |
- Tao, Feng, et al.
(författare)
-
Microbial carbon use efficiency promotes global soil carbon storage
- 2023
-
Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 618:7967, s. 981-985
-
Tidskriftsartikel (refereegranskat)abstract
- Soils store more carbon than other terrestrial ecosystems. How soil organic carbon (SOC) forms and persists remains uncertain, which makes it challenging to understand how it will respond to climatic change. It has been suggested that soil microorganisms play an important role in SOC formation, preservation and loss. Although microorganisms affect the accumulation and loss of soil organic matter through many pathways, microbial carbon use efficiency (CUE) is an integrative metric that can capture the balance of these processes. Although CUE has the potential to act as a predictor of variation in SOC storage, the role of CUE in SOC persistence remains unresolved. Here we examine the relationship between CUE and the preservation of SOC, and interactions with climate, vegetation and edaphic properties, using a combination of global-scale datasets, a microbial-process explicit model, data assimilation, deep learning and meta-analysis. We find that CUE is at least four times as important as other evaluated factors, such as carbon input, decomposition or vertical transport, in determining SOC storage and its spatial variation across the globe. In addition, CUE shows a positive correlation with SOC content. Our findings point to microbial CUE as a major determinant of global SOC storage. Understanding the microbial processes underlying CUE and their environmental dependence may help the prediction of SOC feedback to a changing climate.
|
|
