Tubular structures created by precipitation abound in nature, from chimneys at hydrothermal vents to soda straws in caves. Their formation is controlled by chemical gradients within which precipitation occurs, defining a surface that templates the growing structure. We report a self-organized periodic templating mechanism producing tubular structures electrochemically in iron-ammonium-sulfate solutions; iron oxides precipitate on the surface of bubbles that linger at the tube rim and then detach, leaving behind a ring of material. The acid-base and redox gradients spontaneously generated by diffusion of ammonia from the bubble into solution organize radial compositional layering within the tube wall, a mechanism studied on a larger scale by complex Liesegang patterns of iron oxides formed as ammonia diffuses through a gel containing FeSO(4). When magnetite forms within the wall, a tube may grow curved in an external magnetic field. Connections with free-boundary problems in speleothem formation are emphasized.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC511016 | PMC |
| http://dx.doi.org/10.1073/pnas.0404544101 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Contributions of Both the Eastman Entropy of Transfer and Electric Double Layer to the Electromotive Force of Ionic Thermoelectric Supercapacitors.
ACS Appl Mater Interfaces
January 2025
Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
Recently, ionic thermoelectric supercapacitors have gained attention because of their high open circuit voltages, even for ions that are redox inactive. As a source of open circuit voltage (electromotive force), an asymmetry in electric double layers developed by the adsorption of ions at the electrode surfaces kept at different temperatures has previously been proposed. As another source, the Eastman entropy of transfer, which is related to the Soret coefficient, has been considered.
View Article and Find Full Text PDFSignificant microplastic accumulation and burial in the intertidal sedimentary environments of the Yellow River Delta.
J Hazard Mater
January 2025
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address:
Estuarine intertidal habitats provide a dynamic and distinctive environment for the transport of microplastics, yet their migration and accumulation in these areas remain poorly understood. Herein, the spatial distribution patterns of microplastics in the estuarine sedimentary environment of the Yellow River Delta were investigated across elevation and depth gradients. Compared to the subtidal and supratidal zones, the estuarine intertidal zone exhibited the highest microplastic abundance in sediment (1027 ± 29 items/kg).
View Article and Find Full Text PDFAcetochlor degradation in anaerobic microcosms with hyporheic sediments: Insights from biogeochemical data, transformation products, and isotope analysis.
Water Res
December 2024
Hubei Key Laboratory of Yangtze River Basin Environmental Aquatic Science, School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 430074, Wuhan, PR China. Electronic address:
Steep redox gradients and diverse microbial communities in the anaerobic hyporheic zone create complex pathways for the degradation of herbicides, often linked to various terminal electron-accepting processes (TEAPs). Identifying the degradation pathways and their controlling factors under various TEAPs is of great significance for understanding mechanisms of water purification in the hyporheic zone. However, current research on herbicides in this area remains insufficient.
View Article and Find Full Text PDFIntegrated use of electrochemical anaerobic reactors and genomic based modeling for characterizing methanogenic activity in microbial communities exposed to BTEX contamination.
Environ Res
December 2024
Newe Ya'ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel. Electronic address:
In soil polluted with benzene, toluene, ethylbenzene, and xylenes (BTEX), oxygen is rapidly depleted by aerobic respiration, creating a redox gradient across the plume. Under anaerobic conditions, BTEX biodegradation is then coupled with fermentation and methanogenesis. This study aimed to characterize this multi-step process, focusing on the interactions and functional roles of key microbial groups involved.
View Article and Find Full Text PDFInterpretable machine learning models reveal the partnership of microplastics and perfluoroalkyl substances in sediments at a century scale.
J Hazard Mater
December 2024
School of Environment, Nanjing Normal University, Nanjing 210023, China; Jiangsu Province Engineering Research Center of Environmental Risk Prevention and Emergency Response Technology, Nanjing 210023, China. Electronic address:
It is challenging to explore the complex interactions between perfluoroalkyl substances (PFASs) and microplastics in lake sediments. The partnership of perfluoroalkyl substances (PFASs) and microplastics in lake sediments are difficult to determine experimentally. This study utilized sediment cores from Taihu Lake to reconstruct the coexistence history and innovatively reveal the collaboration between PFASs and microplastics by using post-hoc interpretable machine learning methods.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!