Dynamic behaviour of ISFET-based sensor-actuator systems

Rapid acid-base titrations can be performed at the surface of a noble-metal electrode with coulometrically generated ions. An ISFET is used as an indicator electrode to detect the equivalence point in the resulting titration curve. The time needed to reach the equivalence point is typically 0.5 to 10 s for acid/base concentrations ranging from 0.5 × 10−3 to 20 × 10−3 mol l−1.\ud \ud A model is presented describing the concentration profiles which appear during the coulometric generation of ions. The result of this model is in good agreement with corresponding measurements. These measurements are carried out with two different actuator electrodes, of which the processing steps are described

A micro CO2 gas sensor based on sensing of pH-sensitive hydrogel swelling by means of a pressure sensor

In this paper a sensor is presented for the detection of carbon dioxide gas inside the stomach in order to diagnose gastrointestinal ischemia. The operational principle of the sensor is measuring the CO/sub 2/ induced pressure generation of a confined pH-sensitive hydrogel by means of a micro pressure sensor. The sensor is capable of measuring CO/sub 2/ with a response time between 2 and 4 minutes and a maximum pressure of 0.29/spl times/10/sup 5/ Pa at 20 kPa CO/sub 2/. The sensor is able to resist up to 1 M HCl acid as can be present inside the stomach. The results are very promising for real application and clinical trials are planned

Seasonal Variability of Forces Controlling Sedimentation in the Sundarbans National Forest, Bangladesh

Southwest Bangladesh, located on the Ganges-Brahmaputra-Meghna delta, is experiencing the impacts of sea level rise (SLR) due to processes at both the local and global scale. In particular, regional alterations of the hydrodynamic network, due to embankment construction, have drastically altered effective SLR, placing millions of inhabitants at risk of prolonged inundation, and threatening the world\u27s largest continuous mangrove stand, the Sundarbans National Forest (SNF). In order to effectively employ landscape recovery solutions, an understanding of local sediment transport and deposition is critical. This field-based study investigates the sediment dynamics between the mangrove platform and tidal channels of the SNF using data from a variety of instruments and sediment samples collected within a forested sub-basin (similar to 20 km(2)) fed by a major tidal channel. We observe profound seasonal variability within the sub-basin, with the wet season exhibiting a deeper and longer inundation of the mangrove platform and greater suspended sediment concentrations (SSC). Further, there exists a trend of decreasing SSC and median grain size from the perimeter of the SNF to the interior, and decreasing SSC from the tidal channel to the platform at both locations. We project seasonal platform sedimentation rates ranging from 0.17 +/- 0.16 cm in the dry season to 1.8 +/- 0.35 cm in the wet season. Importantly, the annual deposition rate measured at either location is sufficiently rapid to keep pace with observed rates of effective SLR published in other studies (similar to 1.0-1.7 cm/year). Based on our results, it appears that many controls on sedimentation are both covariant and of similar importance to land aggradation in the SNF. While inundation depth and frequency will likely increase under future SLR scenarios, sediment supply is threatened by India\u27s proposed River Linking Project, which could decrease the sediment loads of the Ganges and Brahmaputra Rivers by as much as 75 and 25%, respectively. These rivers provide the sediment for the entire delta, and we predict that with decreasing SSC, some regions-particularly interior sediment-depleted regions-may begin to deteriorate and become submerged, including within the SNF

Seasonal Variability of Forces Controlling Sedimentation in the Sundarbans National Forest, Bangladesh

Southwest Bangladesh, located on the Ganges-Brahmaputra-Meghna delta, is experiencing the impacts of sea level rise (SLR) due to processes at both the local and global scale. In particular, regional alterations of the hydrodynamic network, due to embankment construction, have drastically altered effective SLR, placing millions of inhabitants at risk of prolonged inundation, and threatening the world’s largest continuous mangrove stand, the Sundarbans National Forest (SNF). In order to effectively employ landscape recovery solutions, an understanding of local sediment transport and deposition is critical. This field-based study investigates the sediment dynamics between the mangrove platform and tidal channels of the SNF using data from a variety of instruments and sediment samples collected within a forested sub-basin (∼20 km2) fed by a major tidal channel. We observe profound seasonal variability within the sub-basin, with the wet season exhibiting a deeper and longer inundation of the mangrove platform and greater suspended sediment concentrations (SSC). Further, there exists a trend of decreasing SSC and median grain size from the perimeter of the SNF to the interior, and decreasing SSC from the tidal channel to the platform at both locations. We project seasonal platform sedimentation rates ranging from 0.17 ± 0.16 cm in the dry season to 1.8 ± 0.35 cm in the wet season. Importantly, the annual deposition rate measured at either location is sufficiently rapid to keep pace with observed rates of effective SLR published in other studies (∼1.0–1.7 cm/year). Based on our results, it appears that many controls on sedimentation are both covariant and of similar importance to land aggradation in the SNF. While inundation depth and frequency will likely increase under future SLR scenarios, sediment supply is threatened by India’s proposed River Linking Project, which could decrease the sediment loads of the Ganges and Brahmaputra Rivers by as much as 75 and 25%, respectively. These rivers provide the sediment for the entire delta, and we predict that with decreasing SSC, some regions—particularly interior sediment-depleted regions—may begin to deteriorate and become submerged, including within the SNF

Surface Elevation and Sedimentation Dynamics in the Ganges-Brahmaputra Tidal Delta Plain, Bangladesh: Evidence for Mangrove Adaptation to Human-Induced Tidal Amplification

In the Ganges-Brahmaputra (G-B) delta, periodic flooding of the land surface during the tidal cycle coupled with enormous sediment delivery during the monsoon promotes sediment accretion and surface elevation gain through time. However, over the past several decades, widespread embankment (“polder”) construction in the GB tidal delta plain has led to numerous environmental disturbances, including channel siltation and tide range amplification. While previous research indicates that rates of sediment accretion are relatively high in the G-B tidal delta plain, it remains unclear if and how surface elevation is maintaining pace with relative sea-level rise (RSLR) in this region. In this study, we utilize an array of surface elevation tables, sediment traps, and groundwater piezometers to provide longitudinal trends of sedimentation and elevation dynamics with respect to local platform elevation and associated hydroperiod. Two hydro-geomorphic settings of the Sundarbans mangrove forest are compared: higher elevation stream-bank and lower elevation interior. Seasonal measurements over a time span of 5 years reveal that elevation gain is occurring in all settings, with the highest rates observed at elevated stream-bank zones. Elevation gain occurs primarily in response to sediment accretion, with possible minor contributions from pore-water storage and swelling of clay minerals during the monsoon season (i.e., belowground biomass and organic contribution is minimal). As a result, elevation loss and shallow subsidence in the G-B delta is unlikely to be caused by compaction of organic-rich soils, but rather appears to be controlled by seasonal lowering of the groundwater table and compaction of clay minerals. Rates of surface elevation gain in the Sundarbans greatly exceed rates of RSLR and more closely follow rates of RSLR augmented from tide range amplification, indicating that this landscape is adapting to human-induced environmental change. The proceedings of this study underscore the adaptability of the natural G-B tidal delta plain to local environmental disturbances, with the caveat that these defenses may be lost to future upstream reductions in sediment supply

PHARAO Laser Source Flight Model: Design and Performances

In this paper, we describe the design and the main performances of the PHARAO laser source flight model. PHARAO is a laser cooled cesium clock specially designed for operation in space and the laser source is one of the main sub-systems. The flight model presented in this work is the first remote-controlled laser system designed for spaceborne cold atom manipulation. The main challenges arise from mechanical compatibility with space constraints, which impose a high level of compactness, a low electric power consumption, a wide range of operating temperature and a vacuum environment. We describe the main functions of the laser source and give an overview of the main technologies developed for this instrument. We present some results of the qualification process. The characteristics of the laser source flight model, and their impact on the clock performances, have been verified in operational conditions.Comment: Accepted for publication in Review of Scientific Instrument

Proton acceleration by irradiation of isolated spheres with an intense laser pulse

We report on experiments irradiating isolated plastic spheres with a peak laser intensity of 2-3 x 10(20) W cm(-2). With a laser focal spot size of 10 mu m full width half maximum (FWHM) the sphere diameter was varied between 520 nm and 19.3 mu m. Maximum proton energies of similar to 25 MeV are achieved for targets matching the focal spot size of 10 mu m in diameter or being slightly smaller. For smaller spheres the kinetic energy distributions of protons become nonmonotonic, indicating a change in the accelerating mechanism from ambipolar expansion towards a regime dominated by effects caused by Coulomb repulsion of ions. The energy conversion efficiency from laser energy to proton kinetic energy is optimized when the target diameter matches the laser focal spot size with efficiencies reaching the percent level. The change of proton acceleration efficiency with target size can be attributed to the reduced cross-sectional overlap of subfocus targets with the laser. Reported experimental observations are in line with 3D3V particle in cell simulations. They make use of well-defined targets and point out pathways for future applications and experiments.DFG via the Cluster of Excellence Munich-Centre for Advanced Photonics (MAP) Transregio SFB TR18NNSA DE-NA0002008Super-MUC pr48meIvo CermakCGC Instruments in design and realization of the Paul trap systemIMPRS-APSLMUexcellent Junior Research FundDAAD|ToIFEEuropean Union's Horizon research and innovation programme 633053Physic