Stimuli-responsive hydrogels are materials with great potential for development of active functionalities in fluidics and micro-fluidics. Based on the current state of research on pH sensors, hydrogel sensors are described qualitatively and quantitatively for the first time. The review introduces the physical background of the special properties of stimuli-responsive hydrogels. Following, transducers are described which are able to convert the non-electrical changes of the physical properties of stimuli-responsive hydrogels into an electrical signal. Finally, the specific sensor properties, design rules and general conditions for sensor applications are discussed.
Grant Kristofor Wayne Dawson, Suzanne D. Golding, Dirk Kirste
et al.
Detailed geochemical modelling of the potential groundwater impacts of CO2 geo-sequestration requires site-specific knowledge of how mobile elements are hosted within rocks. We present a simple sequential extraction procedure analogous to pH conditions produced by different partial pressures of carbon dioxide (CO2) in contact with water. The procedure consists of three sequential steps: Water at pH 7; acetic acid–ammonium acetate at pH 5 and then at pH 3, with the amounts of specific elements extracted by each step considered with respect to whole-rock total element abundance. Our purpose in developing this procedure is three-fold: 1) identify readily mobilised suites of elements for groundwater baseline and monitor bore studies; 2) provide insights regarding the mode/s of occurrence of easily extracted elements within rock samples; and 3) suggest possible mechanisms for the mobilisation of rock-sourced elements into groundwater under neutral to moderately acidic pH that can inform reactive transport modelling of carbon storage sites. In our case study, the second step extracted most of the main mobile elements of interest.
This study extracted photosynthetic phenology indicators (SOS, POS, EOS) from daily GPP data at the weather-station scale for the mid- to high-latitude regions of the Northern Hemisphere from 2001 to 2019. The resulting dataset covers nearly 60,000 site-years, with more than 1,000 stations maintaining complete 19-year records. Results reveal pronounced spatial variability, with distinct trends across vegetation types and aridity zones. Compared with flux networks and satellite-based products, this dataset greatly enhances data availability for phenology studies and provides a solid foundation for assessing the impacts of local hydrothermal conditions and extreme climate events on phenology.