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  • 1
    Online Resource
    Online Resource
    Berlin, Heidelberg :Springer Berlin / Heidelberg,
    Keywords: Colloids. ; Chemical detectors. ; Biosensors. ; Hydrogels. ; Biosensing Techniques. ; Physicochemical Processes. ; Electronic books.
    Description / Table of Contents: With contributions by numerous experts.
    Type of Medium: Online Resource
    Pages: 1 online resource (278 pages)
    Edition: 1st ed.
    ISBN: 9783540756453
    Series Statement: Springer Series on Chemical Sensors and Biosensors Series ; v.6
    DDC: 541.34513
    Language: English
    Note: 152490_1_En_FM1_OnlinePDF.pdf -- Outline placeholder -- Preface -- Contents -- 152490_1_En_1_Chapter_OnlinePDF.pdf -- Chapter : General Properties of Hydrogels -- Introduction -- Swelling and Elasticity of Hydrogels -- Inhomogeneity of Hydrogels -- Hydrogels with Improved Properties -- References -- 152490_1_En_2_Chapter_OnlinePDF.pdf -- Chapter : Synthesis of Hydrogels -- Chemical Cross-Linking -- Temperature Dependent Swelling -- pH-Dependent Swelling -- Bi-Responsive Materials -- Polymerisation and Cross-Linking -- Effect of Synthesis Temperature -- Effect of Solvent -- Effect of Cross-Linker Concentration -- Effect of Monomer Concentration -- Morphological Characterization and Photo Patterning -- Generation of Hydrogel Patterns -- Cross-Linking and Patterning by Irradiation -- Sol-Gel Analysis -- Radiation Source -- Radiochemical Synthesis of Hydrogels -- Examples of Gel Synthesis -- Patterning -- Gel Point Determination of the Reversible Gelatin Gelling System -- Gel Point -- Gel Point Determination Methods -- Dynamic Light Scattering -- Oscillatory shear rheology -- Gelatin as Example for Reversible Gelation -- Critical Dynamical Exponents for the Gelation Threshold of Gelatin -- Conclusions -- References -- 152490_1_En_3_Chapter_OnlinePDF.pdf -- Chapter : Swelling-Related Processes in Hydrogels -- Thermodynamics of Swelling -- Chemical Potential and Equilibrium Degree of Swelling -- Flory-Rehner Theory, Mixing Part -- Flory-Rehner Theory, Elastic Part -- Outline placeholder -- a) Chemical Potential -- b) Deformation Models -- c) Deformation of Perfect Networks -- Discussion of Flory-Rehner Equation -- Mechanical Power Generation on Example of PVA-PAAc gel -- Kinetics of Swelling -- Diffusion -- Cooperative Diffusion Coefficient -- Time Dependence of the Degree of Swelling -- Volume Phase Transition -- Gels with Fast Response. , Determination of Dcoop of Polyelectrolyte Hydrogels by DLS -- Characterization of Molecular Processes -- Fourier Transform Infrared Spectroscopy and Raman Spectroscopy -- 3.1.1Introduction -- 3.1.2Fourier Transform Infrared Spectroscopy -- 3.1.3Raman Spectroscopy -- 3.1.4Sample Preparation -- Sampling Techniques for FT-IR Spectroscopy -- Deuterium Oxide Instead Water? -- Sampling Techniques for Raman Spectroscopy -- 3.1.5Qualitative Spectral Interpretation -- General Approaches -- The Region 2,000-3,800cm-1 -- The Region 900-2,000cm-1 -- The Region 500-900cm-1 -- 3.1.6FT-IR and Raman Spectra of Hydrogels -- 3.1.7FT-IR and Raman spectroscopic imaging -- FT-IR and Raman Imaging Spectrometer -- Enhanced Data Analysis and Imaging Evaluation -- NMR Imaging -- 3.2.1Application on Network Characterization -- 3.2.2Principle of NMR Imaging -- 3.2.3Examples -- Monitoring of Transport Processes -- Transport Processes for Drug Release -- Volume Phase Transition of a Temperature Sensitive Hydrogel -- Diffusion of Small Molecules into a Swollen Hydrogel -- Distribution of Swelling Agent inside a Swollen Gel -- References -- 152490_1_En_4_Chapter_OnlinePDF.pdf -- Chapter : Modelling and Simulation of the Chemo-Electro-Mechanical Behaviour -- Modelling on Different Scales -- Statistical Theory -- Porous Media Theory -- Coupled Chemo-Electro-Mechanical Model -- Chemical Field -- Electrical Field -- Mechanical Field -- Coupling of the Involved Fields -- Discrete Element Model -- Coupled Chemo-Electro-Mechanical Model -- Discretisation -- Coupling Schemes -- Numerical Simulation of the Chemo-Electrical Field -- Chemical Stimulation -- Electrical Stimulation -- Numerical Simulation of the Chemo-Electro-Mechanical Field -- Chemical Stimulation -- Electrical Stimulation -- Mechanical Stimulation -- Comparison with Experimental Results -- Conclusions and Outlook. , References -- 152490_1_En_5_Chapter_OnlinePDF.pdf -- Chapter : Hydrogels for Chemical Sensors -- Hydrogel-Based Piezoresistive Chemical Sensors -- Operational Principle -- Sensor Design -- Sensor Calibration -- Hydrogel Material Preparation and Characterization -- Thermally Cross-Linked Poly(vinyl Alcohol)/Poly(Acrylic Acid) Blend -- Chemically Cross-Linked N-Isopropylacrylamide -- Photo Cross-Linkable Copolymers -- Materials -- P2VP-block-P(NIPAAm-co-DMIAAm) block copolymer -- PNIPAAm-DMAAm-DMIAAm terpolymer -- PDMAEMA-DMIMA copolymer -- Polymer characterization -- UV Cross-Linking -- Hydrogel Conditioning -- Temperature Sensitivity of PNIPAAm Gels -- pH Sensors -- Sensitivity -- Response Time -- Signal Reproducibility -- Sensors for Concentration Measurements in Aqueous Solutions -- Sensors for Organic Solvents -- Sensors for Salt Concentrations -- Sensors for Metal Ions Concentrations -- Summary -- References -- 152490_1_En_6_Chapter_OnlinePDF.pdf -- Chapter : Hydrogels for Biosensors -- Introduction -- Biosensor Devices -- Enzyme Biosensors -- Immobilization of Enzymes and Whole Cells Via Hydrogel Encapsulation -- Whole-Cell-Based Hydrogel Biosensors -- Amperometric Biosensors -- Redox Polymers -- Multi-Analyte Monitoring Devices -- Characterization of the Stability of Entrapped Enzymes -- Nanocalorimetry -- Smart Hydrogels for Biosensors -- Summary -- References -- 152490_1_En_7_Chapter_OnlinePDF.pdf -- Chapter : Hydrogels for Actuators -- Introduction -- Automatic Microfluidic Systems -- Hydrodynamic Transistors -- Directly Acting Hydrogel Component -- Hydrogel as Servo Drive -- Normally Closed and Normally Open Valves -- Mechanical Adjustability of the Regulation Point -- Fluidic Propulsion -- Chemostat Pumps -- Autonomous Pumps -- Tunable Micro-Lenses -- Microelectromechanical Microfluidic Systems. , Electrothermic and Optoelectrothermic Interface -- Microvalves -- Micropumps -- Diffusion Pumps -- Displacement Micropumps -- Hydrodynamic Microtransistors -- High Resolution Tactile Displays -- Influence of Material and Phase Transition Phenomena on the Operational Characteristics of Hydrogel Elements -- Effects at the Initialisation of Gel Elements -- Conditioning Effect -- Softening Effect -- Volume Change After Polymerisation -- Phenomena at the Volume Phase Transition of Gels -- Intrinsic Shrinkage Barrier Effect -- Extrinsic Shrinkage Barrier Effect -- Two-Step Mechanism of the Volume Phase Transition -- Screening Effect -- Material Enrichment Inside the Hydrogel -- Design and Performance -- Response Time -- Effective Diffusion Length -- Swelling Agent Supply -- Counterforces -- Recirculation of Process Media -- Pressure Resistance and Particle Tolerance -- References -- 152490_1_En_8_Chapter_OnlinePDF.pdf -- Chapter : Polymer Hydrogels to Enable New Medical Therapies -- Hydrogels in Biomedical Applications -- Thermo-Responsive Cell Culture Carriers -- Biohybrid Cell Scaffolds for In Vivo Tissue Engineering -- Summary and Perspective -- References -- 152490_1_En_BM2_OnlinePDF.pdf -- : Index.
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  • 2
    Publication Date: 2020-02-12
    Description: This dataset provides a synthesis of winter ( September-April) in situ soil CO2 flux measurement data from locations across pan-Arctic and Boreal permafrost regions. The in situ data were compiled from 66 published and 21 unpublished studies conducted from 1989-2017. The data sources (publication references) are provided. Sampling sites spanned pan-Arctic Boreal and tundra regions (〉53 Deg N) in continuous, discontinuous, and isolated/sporadic permafrost zones. The CO2 flux measurements were aggregated at the monthly level, or seasonally when monthly data were not available, and are reported as the daily average (g C m-2 day-1) over the interval. Soil moisture and temperature data plus environmental and ecological model driver data (e.g., vegetation type and productivity, soil substrate availability) are also included based on gridded satellite remote sensing and reanalysis sources.
    Language: English
    Type: info:eu-repo/semantics/workingPaper
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  • 3
    Publication Date: 2020-02-14
    Language: English
    Type: info:eu-repo/semantics/article
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  • 4
    Publication Date: 2022-03-23
    Description: Arctic warming is affecting snow cover and soil hydrology, with consequences for carbon sequestration in tundra ecosystems. The scarcity of observations in the Arctic has limited our understanding of the impact of covarying environmental drivers on the carbon balance of tundra ecosystems. In this study, we address some of these uncertainties through a novel record of 119 site-years of summer data from eddy covariance towers representing dominant tundra vegetation types located on continuous permafrost in the Arctic. Here we found that earlier snowmelt was associated with more tundra net CO2 sequestration and higher gross primary productivity (GPP) only in June and July, but with lower net carbon sequestration and lower GPP in August. Although higher evapotranspiration (ET) can result in soil drying with the progression of the summer, we did not find significantly lower soil moisture with earlier snowmelt, nor evidence that water stress affected GPP in the late growing season. Our results suggest that the expected increased CO2 sequestration arising from Arctic warming and the associated increase in growing season length may not materialize if tundra ecosystems are not able to continue sequestering CO2 later in the season.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 5
    Publication Date: 2023-02-02
    Description: The continued warming of the Arctic could release vast stores of carbon into the atmosphere from high-latitude ecosystems, especially from thawing permafrost. Increasing uptake of carbon dioxide (CO2) by vegetation during longer growing seasons may partially offset such release of carbon. However, evidence of significant net annual release of carbon from site-level observations and model simulations across tundra ecosystems has been inconclusive. To address this knowledge gap, we combined top-down observations of atmospheric CO2 concentration enhancements from aircraft and a tall tower, which integrate ecosystem exchange over large regions, with bottom-up observed CO2 fluxes from tundra environments and found that the Alaska North Slope is not a consistent net source nor net sink of CO2 to the atmosphere (ranging from −6 to +6 Tg C yr−1 for 2012–2017). Our analysis suggests that significant biogenic CO2 fluxes from unfrozen terrestrial soils, and likely inland waters, during the early cold season (September–December) are major factors in determining the net annual carbon balance of the North Slope, implying strong sensitivity to the rapidly warming freeze-up period. At the regional level, we find no evidence of the previously reported large late-cold-season (January–April) CO2 emissions to the atmosphere during the study period. Despite the importance of the cold-season CO2 emissions to the annual total, the interannual variability in the net CO2 flux is driven by the variability in growing season fluxes. During the growing season, the regional net CO2 flux is also highly sensitive to the distribution of tundra vegetation types throughout the North Slope. This study shows that quantification and characterization of year-round CO2 fluxes from the heterogeneous terrestrial and aquatic ecosystems in the Arctic using both site-level and atmospheric observations are important to accurately project the Earth system response to future warming.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 6
    Publication Date: 2023-02-07
    Description: Long-term atmospheric CO2 concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength. In this study, we used a record of nearly 100 site-years of eddy covariance data from 11 continuous permafrost tundra sites distributed across the circumpolar Arctic to test the temperature (expressed as growing degree days, GDD) responses of gross primary production (GPP), net ecosystem exchange (NEE), and ecosystem respiration (ER) at different periods of the summer (early, peak, and late summer) including dominant tundra vegetation classes (graminoids and mosses, and shrubs). We further tested GPP, NEE, and ER relationships with soil moisture and vapor pressure deficit to identify potential moisture limitations on plant productivity and net carbon exchange. Our results show a decrease in GPP with rising GDD during the peak summer (July) for both vegetation classes, and a significant relationship between the peak summer GPP and soil moisture after statistically controlling for GDD in a partial correlation analysis. These results suggest that tundra ecosystems might not benefit from increased temperature as much as suggested by several terrestrial biosphere models, if decreased soil moisture limits the peak summer plant productivity, reducing the ability of these ecosystems to sequester carbon during the summer.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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