Determination Of Water Content Research Articles

Obsidian hydration dating by infrared transmission spectroscopy

AbstractThe obsidian dating method converts the quantity of diffused molecular water within a near‐surface hydration layer to elapsed time using an experimentally derived diffusion coefficient predicted from the structural water content of the glass. Infrared spectroscopic transmission measurements on transparent archaeological samples record vibrational responses of water bands in the near‐infrared region, permitting determination of structural water content (OH), and the amount of diffused ambient water (H2O). In this application, the H2O water band at 5200 cm−1 is measured directly. The accuracy of the approach is assessed by an evaluation of the precision of each contributing variable. The new protocol is evaluated using obsidian artifacts from radiocarbon‐dated deposits at Salamanca Cave in Argentina.

A new simple index for characterizing the labile heavy metal concentration in soil by diffusive gradients in thin films technique

Diffusive gradients in thin films technique (DGT) is recognized as a more reliable method for determining labile heavy metal (HM) concentration in soil than traditional destructive methods. However, the current DGT measurement index, CDGT, theoretically underestimates the true labile concentration (Clabile) of HMs in soil and lacks direct comparability with the conventional soil HM content indices due to unit differences. Here, we proposed CDGT-W, a new simple index which is defined as the HM accumulation in the binding layer, normalized to the weight of soil (optimized water content = 100% of the maximum water holding capacity) filled in the open cavity-type DGT device over a specified deployment time (optimized time = 24 h). The procedure for measuring CDGT-W is analogous to that of CDGT but includes precise determination of water content (water/dry soil) and the mass of soil filled in the cavity. We conducted measurements of Cu, Pb, Cr(Ⅵ) and As(V) as CDGT-W, CDGT, solution concentration (Csoln), and CaCl2 extractable concentration (CCaCl2) on three soils with a diverse range of HM concentrations. CDGT-W showed significant linear correlations with all other tested indexes. The ratios of CDGT-W to CCaCl2 varied between 0.30 and 0.98 for all HM–soil combinations with only one exception, a range much greater than CDGT/Csoln (typically <0.1) but lower than 1. This suggested that CDGT-W may more accurately reflect Clabile than CDGT (theoretically underestimates Cliable) and CCaCl2(likely overestimates Cliable). Additionally, CDGT-W measurements for these four HMs exhibited a broad measure concentration range and a low detection limit (mg/kg level). Consequently, CDGT-W may offer a more reliable alternative to CDGT for characterizing Clabile in unsaturated soils.

Self-desiccation behavior of nano-cemented tailings backfill plug: Insights from thermo-mechanical-chemical column experiments

This paper examines the influence of various factors, including the addition of nano-calcium carbonate particles (chemical processes, C) to CPBs, non-isothermal field curing temperatures (thermal factor, T), and field vertical curing stress (mechanical factor, M), on the self-desiccation capacity of CPB plugs. The assessment of self-desiccation involves the determination of pore water pressure (PWP) and volumetric water content (VWC) in the examined CPBs. Thermo-mechanical-chemical (TMC) column experiments were conducted to investigate the interaction among these factors and their collective impact on the evolution of PWP and VWC within the CPB plug. The findings underscore that each factor, both individually and in combination, significantly affects the magnitude and progression of self-desiccation in CPB plugs. Notably, the factors of elevated field temperature and the introduction of nano-calcium carbonate (NC) to the CPB exert the most substantial influence on the extent and enhancement of self-desiccation, whereas the impact of field curing stress in isolation is comparatively much weaker. The integration of nano-calcium carbonate, especially under non-isothermal conditions and concurrent field stress, emerges as a key contributor to enhanced PWP and VWC dissipation rates. The role of non-isothermal field curing temperature is underscored as a significant contributing factor in the self-desiccation of CPB plugs. The results presented in this paper will contribute to a more cost-effective design of CPB plugs and the improved optimization of CPB mixtures with nano-calcium carbonate particles.

Hydrous mantle plume promoted the generation of continental flood basalts in the Tarim large igneous province

Recent research on the water content of large igneous provinces (LIPs) has revealed that water has a significant impact on the formation of LIPs. However, most studies focus on the water content of mafic–ultramafic rocks, while relatively little attention has been paid to the water content of continental flood basalts (CFB), which form the major part of LIPs and are characterized by huge volumes (> 1 × 105 km3) and short eruption times. Here, we determined water contents of clinopyroxene crystals from the Akesu diabase, which is co-genetic with flood basalts of the Tarim LIP in China. Based on these measurements, we obtained a water content of higher than 1.23 ± 0.49 wt.% for the parental magma to the Tarim CFB and a minimum water content of 1230 ± 490 ppm for the mantle source, thus indicating the presence of a hydrous mantle plume. Combined with previous studies, our results suggest that water plays a key role in the formation of the Tarim LIP. Additionally, the whole-rock compositions of the Akesu diabase indicate a contribution of pyroxenite in the mantle source. This is consistent with a model, in which water was brought into the Tarim mantle plume by a subducted oceanic plate that entered the deep mantle.

Non-destructive determination of water content in fruits using Vis-NIR spectroscopy

Visible near-infrared (Vis-NIR) spectroscopy is less accurate for detecting -OH molecules, therefore, the use of Vis-NIR spectroscopy is challenging for samples containing high water content, such as fruits. However, as Vis-NIR spectroscopy is a portable and economical instrument, it can be used in the field by small-scale farmers. This study aimed to evaluate Vis-NIR spectra to measure water content in fruits. Four fruits were used in this study, including dragon fruit, guava, sapodilla and banana (100 pieces each). All fruits were randomly divided into a calibration set (two-thirds of the samples) and a prediction set (one-third of the samples). Water content was predicted using partial least square regression (PLSR) analysis. The PLSR calibration model had a coefficient of determination (R²) of 0.29 for dragon fruit, 0.63 for guava, 0.62 for sapodilla and 0.80 for banana. The prediction model had an R² of 0.11 for dragon fruit, 0.63 for guava, 0.52 for sapodilla and 0.75 for banana. These results show that Vis-NIR spectroscopy has the potential to predict water content in relatively low water-content fruits, such as bananas.

Predicting the Electrical Conductivity of Partially Saturated Frozen Porous Media, a Fractal Model for Wide Ranges of Temperature and Salinity

AbstractThe quantitative determination of liquid water content and salinity in soils is crucial for the preservation of hydrological environments and engineering infrastructures, especially in frozen regions. Electrical conductivity, as a fundamental physical parameter in electrical and electromagnetic non‐destructive techniques, varies significantly with the physical and chemical properties, such as pore water conductivity, salinity, water saturation, and temperature. In this study, accounting for pore size and tortuous length following fractal distributions, we develop a new capillary bundle model for variation of electrical conductivity as a function of temperature in broad water saturation and salinity ranges. In this new model, we consider the contributions of bulk and surface conductivities to the total electrical conductivity. To test this model, a series of laboratory experiments were carried out for different initial water saturations and salinities using an electrical resistance apparatus and a nuclear magnetic resonance method. The experimental results show that unfrozen water saturation and ionic concentration affect the electrical conductivity of unsaturated frozen soils. Furthermore, the proposed model is capable of fitting the main trends of the experimental data from the literature and acquired in this study in unfrozen‐frozen conditions for different water contents. Relying on the proposed model, we also determine the expression of the apparent formation factor, which is significantly sensitive to porosity, water saturation, and temperature. The predicted values of the apparent formation factor also agree very well with the experimental data. This new capillary bundle model provides a new perspective in interpreting electrical monitoring to easily deduce changes in key variables in the cryosphere such as liquid water content and moisture gradients.

Infrared Drying for Water Content Measurements of Soils

Abstract The water content of soils is frequently needed, and its reference value is currently obtained by conventional convection ovens. Infrared (IR) ovens appear to be overlooked by the geotechnical community even though they allow for precise control over temperature, much faster heat transfer, and much better energy efficiency resulting from its inherent low thermal inertia. The European Commission’s climate action enacts several policies for greener, sustainable, and energy efficient solutions. The objective of this study is to investigate the usability and efficiency of IR ovens as the permanent replacement for conventional ovens for supporting a greener and sustainable environment. Particular emphasis is given to precision and energy efficiency through experimental comparisons. The results suggest that IR ovens offer 70 % implied energy savings over conventional ovens while resulting in comparable precision. It is, therefore, proposed to adopt IR ovens as the new and preferred standard for water content determination and to abandon conventional ovens after a transition period.

High-Throughput, Nondestructive, and Biosafe Method to Accurately Quantify Water Content in Human Fecal Samples by Benchtop 1H TD-NMR Analysis for Downstream Bioanalytical and Clinical Uses.

Water or moisture content in human stool samples is an important parameter for bioanalytical and clinical purposes. For bioanalytical use, accurate quantitation of water content in stool can provide the extent of dilution within the stool sample which can further be used for absolute quantitation of various stool based biomarkers. For clinical use, water or moisture content in stool is an important indicator of gastrointestinal health, and its accurate determination can enable quantitative assessment of the Bristol Stool Form Scale. In general, accurate determination of water content of stool samples is cumbersome, low-throughput process and is prone to harmful stool pathogens biocontamination, sample cross-contamination using techniques such as gravimetry and karl fischer titration. Here, we report a novel user-friendly high-throughput method to quantitatively and accurately measure the overall water content in human fecal samples nondestructively and biocontained in a closed tube using benchtop a 1H time domain nuclear magnetic resonance analyzer. We used gravimetry and measurement of various bile acid metabolites in stool to verify the accuracy and robustness of the water content measurement using this technique.

Pharmacodynamics and mechanism of Erigeron breviscapus granules in the treatment of ischemic stroke in mice by regulating sphingolipid metabolism based on metabolomics

AimErigeron breviscapus (Vant.) Hand.-Mazz. (EB) granules is the extract preparation of EB, with clear curative effect and unclear mechanism. This study intends to systematically explore the specific mechanism of EB granules in the treatment of IS from the metabolic perspective. MethodsThe model of transient middle cerebral artery occlusion (tMCAO) in mice was established by the suture-occluded method. The therapeutic effect of EB granules on tMCAO mice was evaluated by behavioral evaluation, brain water content determination, 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and levels of lactate dehydrogenase (LDH) and neuron specific enolase (NSE) in serum. In order to screen differential metabolites, non-targeted metabolomics technology was used to detect the metabolites in serum before and after administration. Univariate statistics, multivariate statistics and bioinformatics were used to analyze the changes of metabolites in serum of tMCAO mice. The possible related mechanism of EB granules in treating IS was screened by pathway enrichment analysis, and the preliminary verification was carried out at animal level by enzyme linked immunosorbent assay (ELISA) and western blot (WB). ResultsEB granules could significantly improve behavior of tMCAO mice, reduce brain water content and cerebral infarction volume, improve morphology of brain tissue, reduce the levels of LDH and NSE in serum. A total of 232 differential metabolites were screened, which were mainly enriched in many biological processes such as sphingolipid metabolism. The differential metabolite S1P and its receptors S1PR1 and S1PR2 in sphingolipid metabolism were verified. The results showed that the level of S1P in brain tissue increased and the protein expression of S1PR1 decreased significantly after modeling, and reversed after administration, but there was no significant difference in the protein expression of S1PR2. ConclusionThe therapeutic effects of EB granules may be related to affecting sphingolipid metabolism through regulating S1P/S1PR1.

Local Water Content in Polymer Gels Measured with Super-Resolved Fluorescence Lifetime Imaging.

Water molecules play an important role in the structure, function, and dynamics of (bio-) materials. A direct access to the number of water molecules in nanoscopic volumes can thus give new molecular insights into materials and allow for fine-tuning their properties in sophisticated applications. The determination of the local water content has become possible by the finding that H2 O quenches the fluorescence of red-emitting dyes. Since deuterated water, D2 O, does not induce significant fluorescence quenching, fluorescence lifetime measurements performed in different H2 O/D2 O-ratios yield the local water concentration. We combined this effect with the recently developed fluorescence lifetime single molecule localization microscopy imaging (FL-SMLM) in order to nanoscopically determine the local water content in microgels, i.e. soft hydrogel particles consisting of a cross-linked polymer swollen in water. The change in water content of thermo-responsive microgels when changing from their swollen state at room temperature to a collapsed state at elevated temperature could be analyzed. A clear decrease in water content was found that was, to our surprise, rather uniform throughout the entire microgel volume. Only a slightly higher water content around the dye was found in the periphery with respect to the center of the swollen microgels.

Lokaler Wassergehalt in Polymergelen bestimmt über superauflösende Fluoreszenzlebensdauer‐Bildgebung

AbstractWassermoleküle spielen eine wichtige Rolle für die Struktur, Funktion und Dynamik von (Bio‐) Materialien. Ein direkter Zugang zur Anzahl der Wassermoleküle in nanoskopischen Volumina kann daher neue molekulare Einblicke in Materialien geben und eine Feinabstimmung ihrer Eigenschaften in anspruchsvollen Anwendungen ermöglichen. Die Bestimmung des lokalen Wassergehalts wurde durch die Entdeckung möglich, dass H2O die Fluoreszenz von rot‐emittierenden Farbstoffen löscht. Da deuteriertes Wasser, D2O, keine signifikante Fluoreszenzlöschung hervorruft, lässt sich über Fluoreszenzlebensdauermessungen bei unterschiedlichen H2O/D2O‐Verhältnissen die lokale Wasserkonzentration bestimmen. Wir kombinierten diesen Effekt mit der vor Kurzem entwickelten Fluoreszenzlebensdauer‐Einzelmolekül‐Lokalisierungsmikroskopie (FL‐SMLM), um die lokale Wasserkonzentration in Mikrogelen, d. h. weichen Hydrogelpartikeln, die aus einem in Wasser gequollenen vernetzten Polymer bestehen, nanoskopisch zu bestimmen. Die Änderung des Wassergehalts von thermoresponsiven Mikrogelen beim Übergang von ihrem gequollenen Zustand bei Raumtemperatur zu einem kollabierten Zustand bei erhöhter Temperatur konnte analysiert werden. Es wurde eine deutliche Abnahme des Wassergehalts festgestellt, die zu unserer Überraschung über das gesamte Mikrogelvolumen recht gleichmäßig war. In der Peripherie der gequollenen Mikrogele war die Wasserkonzentration um den Farbstoff herum nur geringfügig größer als in deren Zentrum.

Calibration Techniques for Water Content Measurements in Solid Biofuels

This paper presents methodologies and equipment for SI-traceable inline measurements of water content (a critical quality parameter) in solid biofuels. Inline measurement systems for water content are commonly used at CHP plants, providing continuous real-time data. However, the accuracy of these systems is in most cases unsatisfactory, mainly because the systems are not calibrated representatively for the relevant material, and until now, calibrations traceable to the SI system have not been available. To provide reliable and accurate inline water content data, new procedures and equipment for calibrating measurement systems were developed. Two reference methods for the determination of water content were developed; one measures the airflow and dewpoint of desorbed water in the air passing a test sample, while the other uses a P2O₅-sensor. Additionally, a transfer standard based on a cavity resonance sensor was developed for fast onsite calibration of the inline sensor at the power plant. This new instrument allows for quick and accurate measurements. The transfer standard is made metrologically traceable to the primary measurement standards. The entire system was demonstrated by calibrating an inline microwave-based (MW) sensor at the CHP plant of VERDO in Randers, Denmark. Thus, a complete metrological traceability chain was established from an industrial to a primary standard.

A planar DGS sensor for moisture analysis in civil construction aggregates

The need for effective methods for analyzing water content in aggregates used in construction materials is important to ensure durability and structural excellence. The realization of the intrinsic limitations of conventional approaches to moisture analysis in aggregates instigates the search for more effective and precise solutions, especially in samples with varying percentages of water. This study innovates by presenting a compact device, using the Defect Ground Structure (DGS) technique, for the precise determination of the water content in aggregates used in civil construction. The proposed sensor is based on a modified Complementary Split Ring Resonator (CSRR) structure, operating at a resonance frequency of 2.38 GHz. The operating method consists of measuring aggregated samples with different percentages of water to establish an equation relating the resonance frequency to the water content of the material. The results indicate an effective analysis of moisture in aggregated samples, with an average sensitivity of 1.83% and reduced error levels with an average of 2.01%, validating the potential of this sensor to contribute significantly to advances in the area and improving precision and reliability in determination of water content in aggregates used in construction materials.

Transformation of peat deposits and carbon accumulation in post-pyrogenic raised bogs within the taiga zone of West Siberia

The aim of the study was to assess of the transformation of the hydrologic and physical properties of peat deposits and peat accumulation rates in the post-pyrogenic sites of drained fens in the taiga zone of West Siberia. Location and time of the study. Field studies were conducted in 2022 on the Bakchar fen (drained for forestry, seven plots) and Ust-Bakchar fen (drained for peat extraction, three plots) located in the Tomsk region. Methods. Peat sampling was carried out from two boreholes at each plot in the hollow and the hummock. The sampling increment was 5 cm; the total depth was 45–90 cm. Peat samples were taken at nine subsites by the envelope method on each plot in 0–30 cm layer by 10 cm increment for water content determination in laboratory. Laboratory study of peat characteristics was carried out using the following methods: water and ash content measurements (GOST 11306-2013, GOST 11306-2013), estimation of peat decomposition and humification degree, botanical composition (GOST 28245-89), as well as measuring peat bulk density. Carbon stocks in the upper layer of peat deposits was estimated using the values of peat ash content and density. Results. The peat deposit of the upper layers was formed mainly by sphagnum peat with Sphagnum fuscum plant residues predominating. The differences between hollows and hummocks in their peat properties were manifested to a depth of 5–15 cm from the surface of depressions. The burnout of the hollows led to the changes of all peat properties to a depth of 10–15 cm: the changes were more pronounced in ash content, which was 1.5–9 times higher in the 0–5 cm layer as compared with the unburned site. The changes in peat properties on positive relief forms, i.e. moss hummocks, was less evident in the upper 0–5 cm layer, but reached a greater depth of 30 cm. The change was revealed mainly as an increase in peat ash content due to the migration of ash elements from the surface of burnt hollows and as an increase in bulk density due to subsidence of moss hummocks with the died-off sphagnum moss. Although the average water content in postpyrogenic and unburned sites was the same, amounting to 90–91% in the 0–30 cm layer, some difference was observed between the microrelief forms. The post-pyrogenic site in the Bakchar fen was characterized by water content decrease in hollows and hummocks, the maximum values being observed at an altitude near the average surface. In the Ust-Bakchar fen, water content was found to decrease from hollows to hummocks. In the Bakchar fen, 30 years after the fire peat accumulation occurred only on positive microrelief forms, where the 35 cm thick layer formed after the fire. Taking into account the microrelief heterogeneity, carbon accumulation over the post-fire period was estimated as 1.9 kg C/m2 or 60 g C/m2 per year. Peat accumulation seemed much slower in the Ust-Bakchar fen and was apparently absent on most of the surface. The average rate was estimated as 7 g C/m2 per year. Conclusions. The study found fen hollows to be most prone to burnout. The consequences of the fire manifest themselves in the drying of the upper layer of the peat deposit, thus preventing intensive overgrowth by sphagnum mosses 6–8 years after the fire. At the drained for forestry site in the Bakchar fen, 30 years after the fire the peat accumulation rate on moss hummocks was comparable to the rate in the unburned areas.

Inversion of Leaf Water Content of Cinnamomum camphora Based on Preferred Spectral Index and Machine Learning Algorithm

Plant leaf water content significantly influences photosynthetic efficiency and crop yield. Leaf water content (LWC) and equivalent water thickness (EWT) are indicators that reflect the water state within plant tissues, and they play a crucial role in assessing plant water supply and usage. In recent years, there has been a growing focus on the rapid and precise determination of plant water content. In this study, Cinnamomum camphora (C. camphora) was chosen as the subject of investigation. After acquiring spectral data, three types of vegetation indices were computed: the empirical vegetation index, the random combination dual-band vegetation index, and the ‘trilateral’ parameter. Four groups of optimal spectral index screening strategies were established, namely an empirical vegetation index group (G1), a random combination dual-band vegetation index group (G2), a ‘trilateral’ parameter group (G3), and a mixed group (G4). Three algorithms, specifically random forest (RF), radial basis function neural network (RBFNN), and support vector machine (SVM), were employed for the estimation of leaf water content (LWC) and equivalent water thickness (EWT) in mature C. camphora. The results demonstrated that the G4 group displayed superior performance, yielding five optimal spectral indices for LWC: water index (WI), optimized soil-adjusted vegetation index (OSAVI), difference vegetation index (DVI) at wavelengths 734 and 956 nm, first-order difference vegetation index (DVI-FD) at wavelengths 1009 and 774 nm, and red-edge amplitude (Dr). With regard to EWT estimation, the five optimal spectral indices encompassed the red-edge normalized difference vegetation index (RE-NDVI), simple ratio water index (SRWI), difference vegetation index (DVI) at wavelengths 700 and 1167 nm, first-order difference vegetation index (DVI-FD) at wavelengths 1182 and 1514 nm, and red-edge area (SDr). Utilizing these indices as inputs significantly enhanced the accuracy of the models, with the RF model emerging as the most effective for estimating LWC and EWT in C. camphora. Based on the LWC estimation model of the G4 group and the RF algorithm, the determination coefficient (R2) for both the training and test sets reached 0.848 and 0.871, respectively. The root mean square error (RMSE) was 0.568% for the training set and 0.582% for the test set, while the average relative error (MRE) stood at 0.806% and 0.642%, respectively. Regarding the EWT estimation model, R2 values of 0.887 and 0.919 were achieved for the training and test sets, accompanied by RMSE values of 0.6 × 10−3 g·cm−2 and 0.7 × 10−3 g·cm−2, and MRE values of 3.198% and 2.901%, respectively. These findings lay a solid foundation for hyperspectral moisture monitoring in C. camphora and offer valuable reference for the rapid assessment of crop growth status.

Quantitative Determination of Water in Organic Liquids by Ambient Mass Spectrometry

AbstractThis study uses a rapid tandem mass‐spectrometry method to determine water content in complex organic solutions. Emphasis is placed on trace‐water analysis by a fast and accurate alternative to the Karl–Fischer method. In this new method, water is captured by a charge‐labeled molecular probe. Water binds strongly with high specificity to the strongly electrophilic aldehyde site in a charge‐labelled molecule (N‐methylpyridinium); competitive binding by other analytes is effectively discriminated against in the mass‐measurement step. Quantitative determinations are made over a wide concentration range, 0.001 % (10 ppm) to 99 %, with better than 10 % relative standard deviation, along with short (1 min) analysis times using small sample volumes (several μL). Applications include water measurement in simple organic solvents, for example, deuterated solvents, as well as in complex mixtures, for example, organic reaction mixtures. Additionally, this method allows for water monitoring in levitated droplets. Mechanistic investigations into the impact of water on important chemical processes in organic synthesis and environmental science are reported.

Quantitative Determination of Water in Organic Liquids by Ambient Mass Spectrometry.

This study uses a rapid tandem mass-spectrometry method to determine water content in complex organic solutions. Emphasis is placed on trace-water analysis by a fast and accurate alternative to the Karl-Fischer method. In this new method, water is captured by a charge-labeled molecular probe. Water binds strongly with high specificity to the strongly electrophilic aldehyde site in a charge-labelled molecule (N-methylpyridinium); competitive binding by other analytes is effectively discriminated against in the mass-measurement step. Quantitative determinations are made over a wide concentration range, 0.001 % (10 ppm) to 99 %, with better than 10 % relative standard deviation, along with short (1 min) analysis times using small sample volumes (several μL). Applications include water measurement in simple organic solvents, for example, deuterated solvents, as well as in complex mixtures, for example, organic reaction mixtures. Additionally, this method allows for water monitoring in levitated droplets. Mechanistic investigations into the impact of water on important chemical processes in organic synthesis and environmental science are reported.

Determination of Trace Water Using Fluorescence Probes Based on Nitrogen‐Doped Carbon Quantum Dot Fluorescence Senors (Y‐CDs and R‐CDs)

AbstractIn this work, we reported two nitrogen doped carbon quantum dot fluorescence sensors (Y‐CDs and R‐CDs) with good stability and luminescence efficiency, which can be quickly, sensitively and low‐cost for the determination of trace water content in organic solvents. Using o‐phenylenediamine and p‐phenylenediamine as nitrogen sources and terephthalic acid as carbon sources, the preparation was carried out through simple solvothermal synthesis and heteroatom doping. The luminescence characteristics and interaction mechanism with the target were discussed. The results indicate that the two carbon dots can effectively quench the water content in acetone, ethanol, and DMF, as well as physical interactions such as hydrogen bonding and dynamic quenching, which are the reasons for the observed quenching effect. Based on this, a new method for determining water content in organic solvents using carbon quantum dot fluorescence probes has been established. The linear relationship between the fluorescence quenching efficiency F0/F of two carbon quantum dots and the water content in different organic solvents was studied. The detection limits (LOD) of water in acetone, ethanol and N,N‐dimethylformamide (DMF) were 0.17 %, 2.35 %, 0.26 %, respectively, determined by Y‐CDs. The LOQ of acetone, ethanol, and DMF were 0.554 %, 7.83 %, 0.855 %, respectively. The LOD of water in acetone, ethanol and DMF determined by R‐CDs were 0.056 %, 0.69 %, 0.27 % and the LOQ was 0.187 %, 2.290 %, 0.909 %, respectively. Good recovery rates and precision were achieved in practical applications.

Estimating soil water content in a thorny forest ecosystem by time‐lapse electrical resistivity tomography (ERT) and HYDRUS 2D/3D simulations

AbstractDetermination of soil volumetric water content in forest ecosystems is particularly challenging due to deep rooting systems and unknown soil vertical and spatial heterogeneity. This research aims to test two undisturbed methods, electrical resistivity tomography (ERT) and HYDRUS 2D/3D, for 2D determination in a thorny forest ecosystem. The experiment consisted of infiltrating 10 L of water lasting 60 min. During infiltration, ERT measured apparent resistivity by time‐lapse measurements, and was measured with an FDR probe (EnviroSCAN) at 33, 63, 83, 97, and 163 cm depth close to the infiltration site. At the end of infiltration, a soil pit was dug, and 100 measurements of were performed with a TDR in a 10 × 10 cm regular grid. Archie law transformed soil resistivity (ERT) into using manual calibration, verified by an independent dataset. The 2D profile obtained by ERT was qualitatively compared with the HYDRUS 2D/3D one. HYDRUS 2D/3D was parametrized with calibrated parameters obtained with HYDRUS 1D using 106 days of obtained with EnviroSCAN. The results of HYDRUS 1D calibration and verification were satisfactory, with RMSE and Nash‐Sutcliffe coefficients ranging from 0.021 to 0.034 cm3 cm−3 and 0.11 to 0.77, respectively. The forward HYDRUS 2D/3D simulation disagrees with EnviroSCAN data for 33 cm depth. However, it follows the trend with near to zero variation of water content at 63 cm depth. Water content determination by ERT was satisfactory with RMSE for calibration and verification of 0.017 and 0.021 cm3 cm−3. HYDRUS 2D/3D and ERT comparisons were not equal, with a shallower wetting front by ERT and a deeper one for HYDRUS. Still, both wetting fronts agree with the wetting depth estimated by EnviroSCAN. We conclude that both methods are an alternative for determination in heterogeneous and deep soils of forest ecosystems.

Shannon entropy on near-infrared spectroscopy for nondestructively determining water content in oil palm

&lt;span lang="EN-US"&gt;Indonesia is the world’s largest producer of palm oil. To preserve its competitive advantages, the Indonesian oil palm sector must expand high-quality palm oil output. In oil palm quality control, the water content is a crucial parameter as it can be used as a reference to determine the right harvest time. Thus, this study proposed a near-infrared (NIR) spectroscopy as a fast and non-destructive analysis to assess oil palm water content. NIR spectra were processed using Shannon entropy to describe the characteristics at each wavelength. In this study, oil palm fruit samples at various maturity levels were collected with eight different maturity fractions. Based on the analysis, the Shannon entropy value is closely related to any changes in the water content of palm oil. The entropy value has a decreasing trend as the water content increases. The proposed technique can predict the water content of an oil palm with satisfactory performance with values of 0.9746 of coefficient of determination (R&lt;sup&gt;2&lt;/sup&gt;) and 2,487 of root mean square error (RMSE). Application of this model will lead to a fast and accurate prediction system related to oil palm water content.&lt;/span&gt;