A highly selective liquid membrane nitrite microsensor based on the hydrophobic ion-carrier aquocyanocobalt(III)-hepta(2-phenylethyl)-cobrynate is described. The sensor has a tip diameter of 10 to 15 (mu)m. The response is log-linear in freshwater down to 1 (mu)M NO(inf2)(sup-) and in seawater to 10 (mu)M NO(inf2)(sup-). A method is described for preparation of relatively large polyvinyl chloride (PVC)-gelled liquid membrane microsensors with a tip diameter of 5 to 15 (mu)m, having a hydrophilic coating on the tip. The coating and increased tip diameter resulted in more sturdy sensors, with a lower detection limit and a more stable signal than uncoated nitrite sensors with a tip diameter of 1 to 3 (mu)m. The coating protects the sensor membrane from detrimental direct contact with biomass and can be used for all PVC-gelled liquid membrane sensors meant for profiling microbial mats, biofilms, and sediments. Thanks to these improvements, liquid membrane sensors can now be used in complex environmental samples and in situ, e.g., in operating bioreactors. Examples of measurements in denitrifying, nitrifying, and nitrifying/denitrifying biofilms from wastewater treatment plants are shown. In all of these biofilms high nitrite concentrations were found in narrow zones of less than 1 mm.
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http://dx.doi.org/10.1128/aem.63.3.973-977.1997 | DOI Listing |
Chemistry
January 2025
Ruhr Universität Bochum, Anorganische Chemie I, Universitätsstraße 150, NC 3/26, 44801, Bochum, GERMANY.
In recent years, formic acid (FA) has garnered attention as a compelling molecule for various chemical and everyday applications Additionally, with recent studies demonstrating direct FA generation through CO2 electrolysis, it can serve as a stable liquid hydrogen carrier. Nevertheless, FA-permeability via semi-permeable ion‑exchange membranes (FA-crossover) still constitutes a major issue in scalable polymer-electrolyte separated zero-gap electrolyzers, limiting the breakthrough of the technology to the larger-scale. Herein we present a holistic route towards understanding the mechanism of FA-crossover in zero-gap cells.
View Article and Find Full Text PDFHeliyon
January 2025
Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand.
Although the accumulation of random genetic mutations has been traditionally viewed as the main cause of cancer progression, altered mechanobiological profiles of the cells and microenvironment also play a major role as a mutation-independent element. To probe the latter, we have previously reported a microfluidic cell-culture platform with an integrated flexible actuator and its application for sequential cyclic compression of cancer cells. The platform is composed of a control microchannel in a top layer for introducing external pressure, and a polydimethylsiloxane (PDMS) membrane from which a monolithically-integrated actuator protrudes downwards into a cell-culture microchannel.
View Article and Find Full Text PDFGlufosinate (GLUF) and glyphosate (GLY) are nonselective phosphorus-containing amino acid herbicides that are widely used in agricultural gardens and noncultivated areas. These herbicides give rise to a number of key metabolites, with 3-methyl phosphinicopropionic acid (MPPA), -acetyl glufosinate (-acetyl GLUF), aminomethyl phosphonic acid (AMPA), -acetyl aminomethyl phosphonic acid (-acetyl AMPA), -acetyl glyphosate (-acetyl GLY), -methyl glyphosate (-methyl GLY) as the major metabolites obtained from GLUF and GLY. Extensive use of these herbicides may lead to their increased presence in the environment, especially aquatic ecosystems.
View Article and Find Full Text PDFSe Pu
February 2025
Shanghai-MOST Key Laboratory of Health and Disease Genomics, NHC Key Lab of Reproduction Regulation, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Shanghai 200237, China.
Thromboxane A (TXA), a prothrombotic factor that induces platelet aggregation and thrombosis, acts as a vasoconstrictor by activating TXA receptors (TP receptors). TXA is extremely unstable and metabolizes into three major metabolites: 2,3-dinor thromboxane B (2,3-dinor-TXB), 11-dehydro TXB(11-dh-TXB), and 11-dehydro-2,3-dinor TXB(11-dh-2,3-dinor-TXB). 8-Iso-prostaglandin F(8-iso-PGF), a prostaglandin-like compound widely considered the best biomarker of oxidative stress, can also activate TP receptors.
View Article and Find Full Text PDFSe Pu
February 2025
School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China.
Solid-phase microextraction (SPME) is a fast and simple sample preparation technique that enables the enrichment of analytes, and it is used in combination with other detection techniques to provide accurate and sensitive analytical methods. SPME is widely used in environmental monitoring, food safety, life analysis, biomedicine, and other applications. The extractive coating is the core of the SPME technique, and the properties of the extractive coating greatly influence extraction selectivity and efficiency, as well as the enrichment effect.
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