An official website of the United States government
Abstract The dynamics of soil phosphorus (P) control its bioavailability. Yet it remains a challenge to quantify soil P dynamics. Here we developed a soil P dynamics (SPD) model. We then assimilated eight data sets of 426‐day changes in Hedley P fractions into the SPD model, to quantify the dynamics of six major P pools in eight soil samples that are representative of a wide type of soils. The performance of our SPD model was better for labile P, secondary mineral P, and occluded P than for nonoccluded organic P (Po) and primary mineral P. All parameters describing soil P dynamics were approximately constrained by the data sets. The average turnover rates were labile P 0.040 g g−1day−1, nonoccluded Po 0.051 g g−1day−1, secondary mineral P 0.023 g g−1day−1, primary mineral P 0.00088 g g−1day−1, occluded Po 0.0066 g g−1day−1, and occluded inorganic P 0.0065 g g−1day−1, in the greenhouse environment studied. Labile P was transferred on average more to nonoccluded Po (transfer coefficient of 0.42) and secondary mineral P (0.38) than to plants (0.20). Soil pH and organic C concentration were the key soil properties regulating the competition for P between plants and soil secondary minerals. The turnover rate of labile P was positively correlated with that of nonoccluded Po and secondary mineral P. The pool size of labile P was most sensitive to its turnover rate. Overall, we suggest data assimilation can contribute significantly to an improved understanding of soil P dynamics.
more »
« less
Green mechanochemical synthesis of imine-linked covalent organic frameworks for high iodine capture
Delineated here is the first mechanochemical synthesis of covalent organic frameworks (COF) adsorbents that exhibited exceptional iodine adsorption capacities of 6.4–7.1 g g−1, surpassing those of most existing COFs.
more »
« less
- PAR ID:
- 10505328
- Publisher / Repository:
- RSC
- Date Published:
- Journal Name:
- Green Chemistry
- Volume:
- 25
- Issue:
- 16
- ISSN:
- 1463-9262
- Page Range / eLocation ID:
- 6287 to 6296
- Subject(s) / Keyword(s):
- mechanochemical synthesis covalent organic frameworks iodine capture
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract We consider the combined effects that overshooting and the12C(α,γ)16O reaction rate have on variable white dwarf (WD) stellar models. We find that carbon–oxygen (CO) WD models continue to yield pulsation signatures of the current experimental12C(α,γ)16O reaction rate probability distribution function when overshooting is included in the evolution. These signatures hold because the resonating mantle region, encompassing ≃0.2M⊙in a typical ≃0.6M⊙WD model, still undergoes radiative helium burning during the evolution to a WD. Our specific models show two potential low-order adiabatic g-modes,g2andg6, that signalize the12C(α,γ)16O reaction rate probability distribution function. Both g-mode signatures induce average relative period shifts of ΔP/P= 0.44% and ΔP/P= 1.33% forg2andg6, respectively. We find thatg6is a trapped mode, and theg2period signature is inversely proportional to the12C(α,γ)16O reaction rate. Theg6period signature generally separates the slower and faster reaction rates, and has a maximum relative period shift of ΔP/P= 3.45%. We conclude that low-order g-mode periods from CO WDs may still serve as viable probes for the12C(α,γ)16O reaction rate probability distribution function when overshooting is included in the evolution.more » « less
-
Abstract A reverse‐binding‐selectivity between monovalent and divalent cations was observed for two different self‐assembly G16‐hexadecamer and G8‐octamer systems. The dissociation constant between G4‐quadruplex and monomer was calculated via VT‐1H NMR experiments. Quantitative energy profiles revealed entropy as the key factor for the weaker binding toward Ba2+compared with K+in the G8‐octamer system despite stronger ion‐dipole interactions. This study is the first direct comparison of the G4‐quartet binding affinity between mono and divalent cations and will benefit future applications of G‐quadruplex‐related research. Further competition experiments between the G8‐octamer and 18‐crown‐6 with K+demonstrated the potential of this G8system as a new potassium receptor.more » « less
-
The realization of biomass‐derived supercapacitors of high performance is of practical importance for the manufacturing of supercapacitors from green and renewable sources. Herein, the feasibility of constructing high‐performance supercapacitors from potato‐derived activated carbon (AC) is demonstrated. The potato‐derived AC is produced from potato mash through hydrothermal treatment and high‐temperature activation with KOH as agent. The supercapacitors with aqueous electrolyte of 6 mKOH and a mass loading of 5 mg per electrode achieve a specific gravimetric capacitance of 333.7 F g−1per electrode and a specific energy of 11.75 W h g−1at a specific power of 197.6 W kg−1at a current density of 0.4 A g−1under a nominal compressive stress of 7.96 MPa. The supercapacitors with a mass loading of 10 mg per electrode achieve the maximum specific gravimetric capacitance of 340.6 F g−1and a specific energy of 11.75 W h g−1at a specific power of 194.2 W kg−1at a current density of 0.4 A g−1under a nominal compressive stress of 7.96 MPa. Increasing the compaction of electrode materials under compressive stress has the potential to increase the electrochemical performance of supercapacitors.more » « less
