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Installation of subsurface drainage systems has profoundly altered the nitrogen cycle in agricultural regions across the globe, facilitating substantial loss of nitrate (NO3−) to surface water systems. Lack of understanding of the sources and processes controlling NO3− loss from tile‐drained agroecosystems hinders the development of management strategies aimed at reducing this loss. The natural abundance nitrogen and oxygen isotopes of NO3− provide a valuable tool for differentiating nitrogen sources and tracking the biogeochemical transformations acting on NO3−. This study combined multi‐years of tile drainage measurements with NO3− isotopic analysis to examine NO3− source and transport mechanisms in a tile‐drained corn‐soybean field. The tile drainage NO3− isotope data were supplemented by characterization of the nitrogen isotopic composition of potential NO3− sources (fertilizer, soil nitrogen, and crop biomass) in the field and the oxygen isotopic composition of NO3− produced by nitrification in soil incubations. The results show that NO3− isotopes in tile drainage were highly responsive to tile discharge variation and fertilizer input. After accounting for isotopic fractionations during nitrification and denitrification, the isotopic signature of tile drainage NO3− was temporally stable and similar to those of fertilizer and soybean residue during unfertilized periods. This temporal invariance in NO3− isotopic signature indicates a nitrogen legacy effect, possibly resulting from N recycling at the soil microsite scale and a large water storage for NO3− mixing. Collectively, these results demonstrate how combining field NO3− isotope data with knowledge of isotopic fractionations can reveal mechanisms controlling NO3− cycling and transport under complex field conditions. Plain Language Summary: Installation of subsurface tile pipes in many poorly drained agricultural lands has facilitated a substantial loss of nitrate (NO3−) to surface water systems. However, the nitrogen sources and related processes controlling NO3− export from tile‐drained agricultural systems remain unclear. This study employed stable isotope techniques to investigate how NO3− is biologically produced and hydrologically transported in a tile‐drained field. Stable isotopes are chemical variants of the same element and have long been used as a tracer of nitrogen cycling in environmental systems. By combining field measurements of NO3− isotopes in tile drainage with a detailed understanding of how these isotopes are altered by microbial reactions, we estimated the original isotope ratios of NO3− and compared these ratios to those of potential nitrogen sources in the field. The results show that the original isotope ratios of NO3− were similar to those of ammonia fertilizer and soybean biomass nitrogen and did not vary over time when there was no fertilizer input to the system. These findings indicate the presence of a large NO3− pool in the soil and a time lag between the moments when the source nitrogen was introduced into the system and when the NO3− was exported via tile drainage. Key Points: The oxygen isotopic composition of nitrate produced by soil nitrification varied with the degree of soil nitrite accumulationThe dual isotopes of nitrate in tile drainage exhibited coupled variations and were highly responsive to variations in tile dischargeCombining field nitrate isotope data with the isotopic systematics of nitrification reveals a legacy effect controlling nitrate dynamics [ABSTRACT FROM AUTHOR]

Accurately quantifying and predicting the reactive transport of nitrate (NO3− ${{\text{NO}}_{3}}^{-}$) in hydrologic systems continues to be a challenge, due to the complex hydrological and biogeochemical interactions that underlie this transport. Recent advances related to time‐variant water age have led to a new method that probes water mixing and selection behaviors using StorAge Selection (SAS) functions. In this study, SAS functions were applied to investigate storage, water selection behaviors, and NO3− ${{\text{NO}}_{3}}^{-}$ export regimes in a tile‐drained corn‐soybean field. The natural abundance stable nitrogen and oxygen isotopes of tile drainage NO3− ${{\text{NO}}_{3}}^{-}$ were also measured to provide constraints on biogeochemical NO3− ${{\text{NO}}_{3}}^{-}$ transformations. The SAS functions, calibrated using chloride measurements at tile drain outlets, revealed a strong young water preference during tile discharge generation. The use of a time‐variant SAS function for tile discharge generated unique water age dynamics that reveal an inverse storage effect driven by the activation of preferential flow paths and mechanically explain the observed variations in NO3− ${{\text{NO}}_{3}}^{-}$ isotopes. Combining the water age estimates with NO3− ${{\text{NO}}_{3}}^{-}$ isotope fingerprinting shed new light on NO3− ${{\text{NO}}_{3}}^{-}$ export dynamics at the tile‐drain scale, where a large mixing volume and the lack of a strong vertical contrast in NO3− ${{\text{NO}}_{3}}^{-}$ concentration resulted in chemostatic export regimes. For the first time, NO3− ${{\text{NO}}_{3}}^{-}$ isotopes were embedded into a water age‐based transport model to model reactive NO3− ${{\text{NO}}_{3}}^{-}$ transport under transient conditions. The results of this modeling study provided a proof‐of‐concept for the potential of coupling water age modeling with NO3− ${{\text{NO}}_{3}}^{-}$ isotope analysis to elucidate the mechanisms driving reactive NO3− ${{\text{NO}}_{3}}^{-}$ transport. Plain Language Summary: Accurately quantifying the transport and transformation of NO3− ${{\text{NO}}_{3}}^{-}$ in hydrologic systems continues to be a challenging task. In this study, we combined water age modeling with NO3− ${{\text{NO}}_{3}}^{-}$ isotope analysis to understand how hydrological processes, microbial reactions, and management practices interact to control NO3− ${{\text{NO}}_{3}}^{-}$ loss from a tile‐drained agricultural field. While water age is an important descriptor of how water flows through hydrologic systems, NO3− ${{\text{NO}}_{3}}^{-}$ isotopes contain unique information about NO3− ${{\text{NO}}_{3}}^{-}$ sources and microbial reactions that produce, consume, and recycle NO3− ${{\text{NO}}_{3}}^{-}$ during hydrologic transport. Therefore, the coupled use of water age modeling and NO3− ${{\text{NO}}_{3}}^{-}$ isotopes provides complementary information about water flow and microbial NO3− ${{\text{NO}}_{3}}^{-}$ cycling. Results from this study show that tile discharge was fed by younger stored water flowing through big soil pores when the tile drained system was wet. Based on the measured NO3− ${{\text{NO}}_{3}}^{-}$ isotopes, we were able to discern key microbial NO3− ${{\text{NO}}_{3}}^{-}$ cycling reactions that occurred during the transport of NO3− ${{\text{NO}}_{3}}^{-}$ with water, which, in turn, provided important evidence to confirm the dominant mechanism that controls how water flows at the tile‐drain scale. Our finding suggests that combining water age modeling with NO3− ${{\text{NO}}_{3}}^{-}$ isotopes is a promising way forward for modeling coupled water and NO3− ${{\text{NO}}_{3}}^{-}$ transport. Key Points: StorAge Selection‐based water age modeling revealed a strong preference for young water and an inverse storage effect during tile discharge generationNitrate export regime was modulated by an interplay between water mixing, flow path activation, and the vertical distribution of soil nitrateCombining water age modeling with nitrate isotope analysis has the potential to improve the modeling of reactive nitrate transport [ABSTRACT FROM AUTHOR]

Recent evidence suggests that protecting human amnion and chorion matrices (HACM) during processing enhances the performance of HACM for wound repair and tissue regeneration. We utilised a diabetic (db/db) delayed wound healing mouse model. Treatment of db/db full‐thickness excisional wounds with HACM, processed with a polyampholyte preservative accentuated the proliferative phase of wound healing that decreased the time necessary to heal wounds. Polyampholyte protection improved the preservation of growth factors and cytokines during room temperature storage following E‐beam sterilisation and improved its function in wound healing applications. Our findings indicate protected HACM tissue up‐regulated MIP2, NF‐kB, TNF‐α, KI‐67, and Arg1 (0.6‐fold to 1.5‐fold) but those changes were not statistically significant. Immunofluorescent assessment identifying cell activity illustrated an induction of the proliferative phase of wound healing and a switch from an inflammatory macrophage phenotype (M1) to a pro‐regenerative macrophage phenotype (M2a). Genomic profiling of 282 genes was performed using Nanostring from co‐cultures of human macrophages and fibroblasts. The polyampholyte + HACM‐treated group, compared with the HACM or polyampholyte alone groups, had a statistically significant up‐regulation (32–368 fold) of 12 genes primarily involved in macrophage plasticity including CLC7, CD209, CD36, HSD11B1, ICAM1, IL1RN, IL3RA, ITGAX, LSP1, and PLXDC2 (adj. p‐value < 0.05). The polyampholyte alone group demonstrated statistically significant down‐regulation of four genes ADRA2, COL7A1, CSF3, and PTGS2 (adj. p < 0.05). The HACM alone group up‐regulated four genes ATG14, CXCL11, DNMT3A, and THBD, but the results were not statistically significant. Biomechanical measurements indicated that wounds treated with polyampholyte‐protected HACM had more tensile integrity compared with wounds treated with HACM alone. These findings indicate that better protection of HACM during processing stabilises the HACM matrix, which may lead to improved wound healing outcomes. [ABSTRACT FROM AUTHOR]

Gold is epitaxially grown by spontaneous deposition (SD) on Pt(111) and Pt[poly]. It has been demonstrated that in the system of interest the SD takes place as a hybrid process, consisting of the potential-controlled reduction of an adsorbed [AuCl4]- complex along with an electroless reduction of the same complex coupled with Pt surface oxidation over the course of adsorption. This hybrid deposition process is shown to promote an outstanding layer-by-layer growth mode on Pt(111) that involves the formation of smooth films with virtually no surface roughness increase. This finding is seconded by in-situ STM experiments demonstrating that the SD of Au on Au(111) leads to similar growth results. In addition, an adlattice structure of √7 × √7 r19.1° is determined for the [AuCl4]- adsorbate on Au (111) suggesting a theoretical deposited amount of about 15% Au surface coverage per SD cycle. It has been shown that a Pt(111) substrate is completely masked after five cycles of SD followed by layer densification in continuity development. It has also been shown that the Au amount deposited specifically through the electroless route can be controlled by the amount of initial Pt oxidation, the concentration of dissolved O2, and the duration of [AuCl4]- adsorption process. [ABSTRACT FROM AUTHOR]