Range Of Water Contents Research Articles

Cellulose particles filled oil-in-water emulsion: a facile strategy to prepare edible oleogels

Abstract In this work, a facile strategy of filling the O/W emulsions with cellulose particles to prepare edible oleogels was reported. Two preparation processes, particle filling in water phase of emulsion (PFWP) and one pot dispersing (OPD) are adopted. The effect of cellulose particle concentration and water content on the formation and properties of oleogels were evaluated. Results showed that both of the two processes (PFWP and OPD) could form an oleogels, within a wide range of particle concentration (20 wt% – 40 wt%) and water contents (15 wt% – 25 wt%). The formed oleogels have good centrifugal stability, thixotropic recovery properties and thermostability. The storage moduli of the oleogels increased with an increase of cellulose particle concentration, which is associated with the stronger capillary bridges network. Our results provide a fast and simple approach for oil structuring, which should have great potential application in food industry, especially in food bakery.

Updated Weighted-Sum-of-Gray-Gases Model Parameters for a Wide Range of Water and Carbon Dioxide Concentrations and Temperatures up to 5000 K.

The weighted-sum-of-gray-gases model (WSGGM) is a commonly used radiative properties model for combustion engineering applications. This work presents updated WSGGM parameters from our previously published WSGGM to cover a temperature range up to 5000 K for pure H2O and CO2 species as well as mixtures of the two. The gases are considered ideal at all temperatures and new conditions are covered in comparison to existing WSGGM parameters; examples of engineering applications are hydrogen combustion, oxygen-enriched, and oxy-fuel combustion as well as thermal and hybrid plasma systems applying either H2O- or CO2-based plasma conditions. Thus, the parameters are considered relevant in high-temperature processes where gas dissociation effects are unknown. The updated sets of WSGGM parameters are compared to existing WSGGMs by predicting the total emissivity for different gaseous domains; the computational accuracy is assessed using the statistical narrow band model (SNBM) as a reference. Additional comparisons applying the WSGGMs for predicting the radiative source term under nonisothermal and nonhomogeneous conditions in a gaseous domain consisting of two infinite black plates are also included. The results show the suitability of the updated model parameters for such conditions and the increasing deviation error from the SNBM for existing WSGGMs when used outside of their temperature limits. The updated parameters achieve a mean deviation error from the SNBM of below 20% for most cases, which is at a range similar to previous works.

PERFORMANCE OF SPRINKLER AND DRIP IRRIGATION IN CULTIVATION OF CRYSTAL GUAVA (Psidium guajava L.) AT P.T. GGPPG 4 EAST LAMPUNG

The research was conducted at P.T. Great Giant Pineapple Plantation Group 4 (P.T. GGPPG4) Rajabasa Lama 1, Labuhan Ratu District, East Lampung Regency. One of the cultivated plant commodities is crystal guava (Psidium guajava L. cv. Kristal). In order for the crystal guava plants to grow well, the crystal guava plantations are irrigated by means of mini sprinkler irrigation on Block 408 P covering an area of ​​4.2 ha and by drip irrigation method on Block 412 N covering an area of ​​3.46 ha. The research objective was to determine the performance of mini sprinkler irrigation and the performance of drip irrigation on crystal guava production. The uniformity coefficient of drip irrigation water was only 77.20% which was considered sufficient, while for mini sprinkler irrigation it reached 88.49%, which was classified as good based on the classification of the value of the water uniformity coefficient. The condition of the soil water content before and after the application of irrigation water on crystal guava plantations by drip irrigation and mini sprinkler irrigation methods is still within the range of available soil water content so that crystal guava plants can grow and produce well. The total water use of crystal guava plants by drip irrigation method is 2,516 m3/ha, lower than the mini sprinkler irrigation method which reaches 3,260 m3/ha. Productivity of crystal guava irrigation water by drip irrigation at P.T. GGPPG4 reached 11.942 kg/m3, which was much higher than the productivity of crystal guava irrigation using mini sprinkler irrigation which was only 4.965 kg/m3. Productivity of crystal guava water by drip irrigation at P.T. GGPPG4 is classified as very high, whereas with the mini sprinkler irrigation method it is classified as high.

Study on the effect of water on the shear behavior and microstructure of red mudstone

Red mudstone has significant hydrophilicity, that is hard at low water contents and soft and unstable at high water contents, and understanding the whole range of water content on the shear behavior of red mudstone is critical for evaluating red beds landslide stability. However, the deterioration mechanism of red mudstone in the process of gradual humidification is not clear in the whole range of water content. In this study, a series of mechanical and microscopic tests were carried out in the whole range of water content. A mechanical behavior prediction model for the entire process under the coupling of initial damage and load damage was constructed. The results show that the deterioration of shear strength, elastic modulus and strength parameters conforms to the “logistic model” curve with the increase of water content in the whole range of water content. In addition, the water sensitivity of cohesion was higher than the internal friction angle, and it gradually stabilized as water content increased. The weakening mechanism of the mechanical strength in the accelerated decline stage is the initiation and propagation of microcracks caused by mineral expansion, which leads to the corresponding shear behavior. Finally, the constructed damage model can be transformed into different yield conditions through parameter changes. The introduction of coupling damage enables the model to more accurately describe and predict the accelerated attenuation stage of red mudstone in the process of gradual humidification in the whole range of water content.

Thermal diff usivity of soil-peat mixtures: nonlinear dependence on peat content

The thermal diffusivity of the upper plow horizon of the urban soil from the territory of MSU Experimental soil station, lowland packed peat, and their mixtures was studied. The soil from Ap horizon was sieved through a 1 mm sieve and mixed with peat in various proportions; the content of peat in mixtures ranged from 1 to 80% by dry weight. Metal cylinders 10 cm high and 3.8 cm in diameter were filled with soil, peat, and soil-peat mixtures. The thermal diffusivity was measured using the unsteady-state method with a working temperature range of 20–26°C. The heating rate of the packed samples was measured after the samples were placed in a liquid thermostat with a constant water temperature. For each sample, a series of measurements was carried out with a step-by-step change in soil water content from the maximum one after capillary saturation of the sample to the minimum one, corresponding to the air-dry state. Within the studied range of water contents, the thermal diffusivity of different samples changed by a factor of 1.3–3.5; the greatest changes with water content were typical for mineral soil. The thermal diffusivity vs. water content dependence was almost linear for peat, and for soil it was an S-shaped curve with a weakly expressed maximum. The lowest thermal diffusivity was obtained for peat and mixtures with high peat contents; the highest one — for soil without peat additions. The non-linear character of the thermal diffusivity vs. peat content dependence was revealed. Small additions of peat to mineral soil resulted in a noticeable decrease in the thermal diffusivity of the mixture; small additions of soil to peat had practically no effect on thermal diffusivity. The thermal diffusivity of the studied substrates increased with increasing sample bulk density and decreased with increasing organic matter content. It was concluded that the patterns typical for soil-peat mixtures are similar to those earlier obtained for peat-sand mixtures, but in the case of soil-peat mixtures these patterns are less clearly expressed.

PENGARUH PENGGUNAAN KOAGULAN ALAMI SARI BELIMBING WULUH PADA TAHU PUTIH BERDASARKAN PERBEDAAN KONSENTRASI DAN LAMA PENGGUMPALAN

Tofu is a food whose process involves agglomerating soybean curd using coagulants, one of which is vinegar. In addition, from the other side, vinegar acid has shortcomings so that a natural coagulant substitute such as starfruit wuluh is needed. Belimbing wuluh one of the fruits that contains citric acid so that it can be used as a natural coagulant to replace vinegar, besides that it also contains oxalic acid, acetic acid, malic acid, formic acid, ascorbic acid and other compound components. This study aims to determine the effect of star fruit juice concentration and clotting time on the physicochemical and organoleptic properties of white tofu using star fruit as a coagulant. The method used was Randomized Group Design (RGD) using two factors, namely the concentration of Wuluh starfruit juice (factor 1) consisting of 4%, 5% and 6% and the coagulation activity (factor 2) consisting of 20 minutes, 30 minutes and 40 minutes. The testing parameters include protein content, fat content, moisture content, ash content, carbohydrate content, chewiness and organoleptic (scent, taste, color, texture and liking). The results of the analysis showed that there was an effect of the use of star fruit juice concentration and clotting time on protein in white tofu, which ranged from 3.50% - 6.77%; the range of water content ranged from 85.79% - 89.89%, chewiness was 3.08 N - 16.03 N. However, there was no significant effect on ash, fat and carbohydrates. As for the organoleptic test, the results showed a significant effect for scent parameters ranging from 2.80 (somewhat fragrant) - 4.05 (fragrant), color ranging from 2.45 (not bright white) - 3.45 (slightly bright white), texture ranging from 2.85 – 3,65 (slightly chewy) and liking ranging from 3.05 (slightly like) - 3.7 (like).

Examination of the Dry Density Importances in TDR Use and of the ASTM D6780 Standard Based on a New Calibration Procedure

Abstract The use of time domain reflectometry (TDR) to monitor soil water content at either field or laboratory scales is highly common. Regarding the soil dry density, ρd, effect on the TDR application, three main approaches are found in the literature: (1) Ignore the density issue and use calibration to evaluate the water content regardless of the density. This approach is basic, yet common. (2) Include soil density in the calibration equation and use calibration for the water content as a function of both the TDR output and soil density. In this approach, the soil density should be provided from an independent source. (3) Determined ρd from the TDR waveform. In this case both water content and ρd are set from the TDR analysis. In cases where the ρd is not available, in order to use TDR for water content measurement, a decision has to be made whether to address the density issue although it requires resources, or to neglect it. This article reviews this issue and validates the density effect using an efficient TDR calibration methodology. A calibration scheme that controls ρd of the specimen has been developed and applied. The methodology creates continuous calibration curves over a range of volumetric water content from a single test specimen. Based on the results, it has been demonstrated that the soil density has a major effect on the TDR output and it cannot be ignored. In addition, this article presents a unique examination of ASTM D6780, Standard Test Methods for Water Content and Density of Soil In Situ by Time Domain Reflectometry (TDR). The ASTM dry density estimation was found to provide reliable results; however, the gravimetric water contents estimation gives unsatisfactory results, especially for low densities.

Comparison of liquid–liquid phase equilibrium behavior of acetonitrile–water system using choline chloride salt and water-based deep eutectic solvent

The liquid–liquid equilibrium (LLE) data for the ternary systems of (acetonitrile (ACN) + water (W) + choline chloride (ChCl)) and (ACN + W + water-based deep eutectic solvent (WDES) consisting of ChCl:W (1:3)) were measured at 298 K. The consistency of tie-lines was verified by the Bachman and Othmer–Tobias correlations. ChCl as an organic salt and its WDES (within the water content range of less than 50 w%) as green extractants represent feasible performances in terms of selectivity and distribution coefficients for separation of water from acetonitrile-water system in comparison to other inorganic salts and hydrophobic DESs. ChCl in the (ACN + W + ChCl) system can separate water from the solution in the form of hydrate ions while WDES in the (ACN + W + WDES) system tends to absorb water by intermolecular forces. The experimental data of the (ACN + W + ChCl) system was correlated using the symmetric electrolyte non-random two liquid (e-NRTL) model while the equilibrium data of the (ACN + W + WDES) system was correlated using NRTL and universal quasi-chemical activity coefficient (UNIQUAC) models. ChCl in the form of salt represents a better separation performance than WDES for water removal from the acetonitrile mixture. Meanwhile, WDES might be considered to be superior compared to ChCl in terms of regeneration energy consumption and operating considerations.

Effects of seawater on properties of bentonite cut-off walls with/without cement addition

Bentonite-based cut-off walls have been widely used to protect coastal areas against seawater intrusion. However, salts contained in coastal soils affect the properties of bentonite cut-off walls, and the interactions between seawater and bentonite minerals with or without cement remain unclear. The aim of this study was therefore to evaluate the effects of seawater on the workability, strength and permeability of bentonite-based mixtures, prepared using three types of bentonite (sodium, calcium and seawater bentonite). The underlying mechanisms were further investigated through Atterberg limits, mineralogical and microstructural analyses. The results showed that cation exchange between seawater and bentonite leads to alterations in montmorillonite type and particle arrangement. This leads to a significantly reduced liquid limit and a slightly decreased plastic limit of bentonite, therefore narrowing the range of workable water content for bentonite–sand mixtures. Compared with sodium/calcium bentonite, seawater bentonite was less impacted by seawater, but showed a larger increment in workability after cement addition due to palygorskite dissolution. Under similar workability, the bentonite–sand–cement mixture with calcium bentonite yielded the highest strength and the lowest permeability. These findings illustrate correlations between bentonite mineral alterations and the properties of bentonite–sand mixtures with or without cement, and offer guidance for the construction of cut-off walls in coastal regions.

Different States of water in α-Cyclodextrin hydrates

The pressure of saturated and unsaturated water vapor over α-CD·nH2O hydrates has been measured by static method with membrane-gauge manometer under conditions of complete loss of water. The temperature dependences of water vapor pressure have been obtained in the wide range of temperatures (287–469 K), pressures (0.04–34.95 kPa) and water content (0.17 ≤ n ≤ 6.0).The data obtained indicate the presence of water molecules with different volatility in α-CD·nH2O hydrates. Water molecules with lower volatility can be considered “external”, included in the network of intermolecular hydrogen bonds, while water molecules with higher volatility, discovered in our previous study, are considered “internal”, presumably located in the α-CD cavity. For each composition, the amount of “external” and “internal” water has been determined and the equations described the dependence of the content of each type of water on n in α-CD·nH2O have been obtained. The analytical expressions for the lnp – 1/T dependences as well as the values of enthalpy and entropy of processes studied have been calculated. Experimental data were used to obtain the Gibbs energy changes when “external” water molecules bind to the α-CD framework. The values obtained are differed from the values for “internal” water given in our previous study. The phase transition in α-CD·nH2O revealed in our previous study is also observed in this work and its thermodynamic characteristics are in good agreement with the results obtained earlier. The findings have been confirmed by 1H NMR studies.

A bio-based, self-healable, conductive rubber film with oxidized cellulose nanofiber segregated network

Rubber composites are indispensable in all areas of our daily lives. However, the formation of permanent crosslinked networks in rubber materials makes it difficult to recycle, resulting in a non-negligible waste of resources. In this paper, a vulcanization-free, fully bio-sourced rubber composite was prepared by using oxidized natural rubber (oNR) and oxidized cellulose nanofibers (TOCFs). TOCFs are selectively dispersed between the latex particles to form a segregated network. Meanwhile, the formation of hydrogen-bonding between oxygenated polar groups of oNR and abundant hydroxyl and carboxyl groups of TOCFs improves their interfacial interactions. This special structure promotes strain-induced crystallization (SIC) behavior of oNR matrix, giving its tensile strength up to 14.7 MPa. Furthermore, the oNR/TOCFs film shows excellent self-healing efficiency (96 %) at 40 °C for 5 h. The hygroscopicity of the TOCFs segregated network can turn the oNR/TOCFs film to be a conductive film by regulating the absorbed water content. The film has high conductivity (0.05 S/m) at a water content of 8.99 wt%, and the resistance change (RV/R0) can be varied between 1–5.9 × 10−6 at a water content range of 0–8.99 wt%, which makes it have potential for a wide range of humidity monitoring applications.

Influence of soil conditioners for enhanced water retention on the accuracy and longer‐term deployment of widely used soil moisture sensors

AbstractIn precision agriculture, water content sensors are fundamental to monitor soil moisture and hence optimize irrigation scheduling. Climate‐smart agriculture has also focused on improving soil moisture retention by using soil conditioners. However, despite that ‘sensor deployment’ and ‘soil conditioners’ are both intended to improve water use efficiency, data are lacking on the responses of soil water sensors to soil conditioners for enhanced water holding capacity. We evaluated soil moisture sensor readings taken in a sandy loam soil, with added biochar (2.5% w/w), compost (5% w/w), hydrogel (0.6% w/w) and water treatment residues (WTR; 5% w/w). The soils were saturated and then subjected to wetting and drying cycles. Measurements were taken continuously using multiple commercial sensors: ML3 and SM150T soil moisture sensors (Delta‐T Devices) as well as EC‐5 soil moisture sensors (Meter). The accuracy of the tested sensors was reduced by the addition of conditioners in the following order: biochar <WTR<compost <hydrogel. Sensor accuracy was highly dependent on soil water content, with larger deviations from actual values when soil water content <0.14 m3 m−3. All sensors performed best at mid values of soil water content (0.14–0.33 m3 m−3), where ML3, SM150T and EC‐5 sensor readings did not differ significantly from the actual water content in unamended soil. The presence of conditioners did affect such accuracy, but the application of a soil + conditioner − specific calibration was effective in increasing sensor accuracy in this water content range.

Water and moganite participation in agates from Bou Hamza (Morocco)

Basalt-hosted monocentric agates from Bou Hamza (Morocco) were examined to unravel a discrete relationship between moganite content, water content, and the abundance of various types of chalcedony/quartz microtextures, so that the agate-forming process is refined. Herein, moganite content is noticeably low in length-slow chalcedony (quartzine, up to 18 wt.%), as compared with the co-occurring length-fast (LF) chalcedony (up to 31 wt.%). Such a type of disparity reflects a stabilization of the crystallization front during the formation of chalcedonic bands. Recrystallization-related quartz types (i.e. feathery and mosaic/jigsaw puzzle) show low and high moganite content (0 and up to 34 wt.%, respectively) since they have likely originated from different silica precursors (i.e. opaline and chalcedonic, respectively). Meanwhile, the initial formation of mosaic quartz can be exclusively witnessed in the so-called zebraic variety of length-fast chalcedony (i.e. with twisted fibres) that should be hence regarded as a ,,metastable” variety of silica though. The range of total water content remains quite stable across chalcedonic bands (0.5–0.6 wt%) and reaches the highest values (0.7 wt%) in feathery quartz. However, there is rather a general negative relationship between the content of molecular water and silanol-group water. This can stem from the recycling of water species following the condensation reaction of silanols within the agate geodes. The agates originated from Fe-Ti-bearing solutions that co-precipitated goethite, hematite, and rutile, but also contain minor low-grade carbonaceous material.

Coordination, hydration, and diffusion of vanadyl cations in negatively charged polymer membranes

Charged polymer membranes that selectively transport ions are crucial for advancing electrochemical technologies for water purification, resource recovery, and energy generation/storage. Recent studies suggest that the ion selectivity trends of such membranes are due to ion dehydration at the membrane/solution interface, where ions that require less energy to shed their hydration can partition more favorably into the membrane. However, direct evidence of ion dehydration in polymer membranes at relevant conditions is scarce, with claims based primarily on correlations between ion hydration energies and membrane transport properties. This study investigates the electronic environment, local coordination, and hydration of vanadyl counter-ion in negatively charged membranes with broadly varying water content via x-ray absorption spectroscopy. The results highlight that vanadyl counter-ions maintain similar oxidation state, electronic state, and coordination number in the membranes as in aqueous solutions of vanadyl sulfate and that vanadyl dehydration is unlikely in these membranes. However, as the membrane water content decreases, the vanadyl diffusion coefficient decreases and the activation energy of diffusion increases. We attribute these significant changes in membrane transport properties to increased Coulombic interactions between vanadyl and the fixed charge groups, resulting from a decreased dielectric constant of the membrane, rather than to ion dehydration at the membrane/solution interface. This study represents significant progress in understanding the mechanisms that govern ion transport in charged polymer membranes over a broad range of water content, highlighting the critical role of Coulombic interactions between the fixed charges and mobile ions.

Heterogeneous pumice populations of the 52 ± 3 ka Maninjau caldera-forming eruption, West Sumatra, Indonesia: Evidence of multiple magma reservoirs feeding a large silicic eruption

Three color variations of grey members (including grey and banded juvenile clasts) were observed in the 52 ka ignimbrite deposits of Maninjau caldera, Indonesia; namely dark grey (DGM), pale grey (PGM), and light grey (LGM). All grey members were phenocryst-rich ( 24, 20, and 31 % for DGM, PGM, and LGM, respectively) and comprise plagioclase, pyroxene, amphibole, biotite, and oxides as the main phenocryst phases; however, apatite is exclusively present in DGM. Plagioclase with unzoned and coarsely sieved texture was observed in all grey members, while finely sieved and oscillatory zoned textures were exclusive in LGM. Notably, DGM is characterized by the highest MgO value among all grey members, followed by PGM and LGM (∼0.72, 0.46, and 0.34 wt% MgO under ∼74.0 wt% SiO2, respectively). Based on the amphibole geothermobarometer and plagioclase hygrometer, we found that all grey magmas were stored at a relatively similar range of pressure and water content, but DGM yields a higher apparent temperature than those of PGM and LGM. Such distinctive petrography and chemical characteristics, coupled with different temperature conditions strongly suggest that each grey member originated from different magma bodies, which were stored below the most voluminous white magma (the source of white pumice). The sudden decompression of the white magma via overpressure causes destabilization to the smaller grey magmatic bodies, allowing them to rise and erupt as grey and banded pumices during the final eruption stage. Our results enrich the evidence of the formation of multiple magma reservoirs in large-silicic magmatic systems, which might be a common behavior before large eruptions. Moreover, our detailed glass compositions for each juvenile type may be useful for further regional tephrochronology studies.

Overlooked biocrust impacts on surface soil thermal properties: Evidence from heat‐pulse sensing on large volume samples

AbstractBiocrusts are a critical surface cover in global drylands, but knowledge about their influences on surface soil thermal properties are still lacking because it is quite challenging to make accurate thermal property measurements for biocrust layers, which are only millimetres thick. In this study, we repacked biocrust layers (moss‐ and cyanobacteria‐dominated, respectively) that had the same material as the original intact biocrusts but was more homogeneous and thicker. The thermal conductivity (λ), heat capacity (C) and thermal diffusivity (k) of the repacked and intact biocrusts were measured by the heat pulse (HP) technique at different mass water contents (θm) and mass ratios (Wt), and the differences between repacked and intact biocrusts were analysed. Our results show that biocrusts substantially alter the thermal properties of the soil surface. The average λ of moss (0.37 W m−1 K−1) and cyanobacteria biocrusts (0.90 W m−1 K−1) were reduced by 63.0% and 10.3% compared with bare soil (1.00 W m−1 K−1), respectively. Edge effects including heat loss and water evaporation caused the λ and k of the biocrusts to be underestimated, but the C to be overestimated. The differences in thermal properties were significant (p <0.001), except for the differences in thermal conductivity between repacked and intact cyanobacteria biocrusts, which were not significant (p = 0.379). Specifically, in the volumetric water content (θv) range of 0 to 20%, the λ and k of the repacked moss biocrusts were underestimated by 59.1% and 61.8%, respectively, and the C was overestimated by 23.9% compared with the intact moss biocrusts. The λ and k of the repacked cyanobacteria biocrusts were underestimated by 15.8% and 79.2%, respectively, and the C was overestimated by 34.8% compared with the intact cyanobacteria biocrusts at the θv range of 0 to 30%. Typically, this difference increased as the θv rises between repacked and intact biocrusts. Our new measurements provide evidence that the thermal properties of biocrusts were previously misjudged due to the measurement limitations imposed by their limited thickness when measured in situ. Biocrusts are likely more significant in regulating soil heat and temperature in drylands than was previously assumed.

17O NMR spectroscopy protocol for the determination of water content in liquids produced by pyrolysis and hydrothermal liquefaction

BackgroundThere is an urgent need to replace fossil-based fuels and chemicals with bio-based, renewable alternatives. Water content is a critical parameter in these liquid products since water affects their quality and properties. However, currently existing methods for bio-oil water content determination have limitations and thus, there is a need to find methods that are versatile, work for a wide water content and sample consistency range repeatably and reliably and are safe for the user and the environment. ResultsIn this research, a17O NMR spectroscopy protocol for water content determination of pyrolysis and hydrothermal liquefaction (HTL) liquids was developed and compared with the standard method Karl Fischer (KF) titration. The approach showed linearity over a wide concentration range, and the changes to the measurement parameters caused only minor effects to the results (≤0.8 percentage points) indicating robustness. The method is also accurate since the absolute differences between experimental and theoretical water contents varied from 0.08 % to 2.09 %. Additionally, the precision of the method, based on the relative standard deviations (RSD) of the three replicate measurements of pyrolysis and HTL samples, was good (RSD <1.82 %). The method was applied to samples containing 1–98 wt% water. Overall, the 17O NMR spectroscopy and KF titration results were well aligned with each other suggesting that the 17O NMR spectroscopy is a potential alternative for the conventional KF titration. SignificanceThis is the first study on the use of 17O NMR spectroscopy protocol for water content quantification. The results indicate that the protocol is an accurate, linear, and precise technique for water content determination of a wide range of samples. Furthermore, the method does not require hazardous chemicals or calibration standards, and the sample preparation is straightforward. The non-destructiveness of the method also enables further studies on the sample, e.g. by 1H NMR spectroscopy.

Substrate Moisture and Temperature Effects on Limestone Reaction Rate in a Peat-Based Substrate

ABSTRACT Lime reaction rate in a container substrate is influenced by temperature and moisture, which are factors that vary between batches of substrate during manufacturing, storage, and crop production. The effects of temperature and moisture on the duration required to achieve a stable substrate-pH are useful information for substrate companies and growers, as well as a key component when modeling lime reaction over time. The pH of a 70 peat : 30 perlite (by volume) substrate was quantified over time under a range of different storage temperature (1.9 to 33.3°C) and substrate volumetric water content (VWC, 0.168 to 0.568 L of H2O/L of substrate). The lime source was a horticultural dolomitic carbonate limestone screened to the fraction that passed through a 100 US mesh but was retained on a 200 US mesh (0.075–0.15 mm) incorporated at 2.67 g·L−1 of substrate. Experiments provided two data sets for calibration and validation. Lime reaction rate increased with increasing substrate temperature and substrate moisture level. The duration required to reach a target substrate-pH value of 6.0 was used to indicate 90% of maximum pH effect from lime. Duration varied from 4 days with the combined high temperature (20.6 and 33.3 °C) and high VWC (0.468 and 0.568 L H2O/L of substrate) to 53 days with low temperature (1.9 °C) and low VWC (0.168 L H2O/L of substrate) for the calibration data set. At an example low VWC of 0.168 L of H2O/L of substrate, the duration required to reach substrate-pH 6.0 at 1.9, 7.8, 10, 20.6, and 33.3°C was 53, 38, 34, 23, and 17 days, respectively. Similarly, if the temperature was held constant at 33.3°C, reducing VWC from 0.568 L H2O/L to 0.128 L H2O/L would decrease lime reaction rate from 100% to 21%, requiring five times the duration to reach an equilibrium pH. Results can be used to compare the relative effects of moisture and temperature on lime reaction rate for substrate manufacturers and growers.

A sigmoidal model for predicting soil thermal conductivity-water content function in room temperature

Apparent thermal conductivity of soil (λ) as a function of soil water content (θ), i.e., λ(θ) is needed to determine the heat flow in soil. The function of λ(θ) can be used in heat and water flow models for simplicity. The objective of this study was to develop a sigmoidal model based on logistic equation for entire range of soil water contents and a wide range of soil textures that can be used in simulation of heat and water flow in respected modes. Further, performance of the developed sigmoidal model along with two other models in literature was evaluated. In the proposed sigmoidal model, the constants of this model are estimated based on empirical multivariate equations by using soil sand content and bulk density. The sigmoidal model was validated with good accuracy for a wide range of soil textures, as the relationship between the measured and predicted λ showed slope and intercept values of nearly 1.0 and 0.0, respectively. Comparison of the results obtained by sigmoidal model with those obtained from Johansen and Lu et al. models indicated that, the sigmoidal model was superior to the other two models in prediction of λ for a wide range of soil textures and soil water contents. Furthermore, comparison with a recently proposed model by Xiong et al. indicated that our sigmoidal model is superior. Therefore, our developed sigmoidal model can be used in heat and water flow models to predict the soil temperature and heat flow.

Unraveling relationship between complex lifetimes and microscopic diffusion in deep eutectic solvents.

Aqueous mixtures of deep eutectic solvents (DESs) have emerged as a subject of interest in recent years for their tailored physicochemical properties. However, a comprehensive understanding of water's multifaceted influence on the microscopic dynamics, including its impact on improved transport properties of the DES, remains elusive. Additionally, the diffusion mechanisms within DESs manifest heterogeneous behavior, intricately tied to the formation and dissociation kinetics of complexes and hydrogen bonds. Therefore, it is imperative to explore the intricate interplay between bond kinetics, diffusion mechanism, and dynamical heterogeneity. This work employs water as an agent to explore their relationships by studying various relaxation phenomena in a DES based on acetamide and lithium perchlorate over a wide range of water concentrations. Notably, acetamide exhibits Fickian yet non-Gaussian diffusion across all water concentrations with Fickian (τf) and Gaussian (τg) timescales following a power-law relationship, τg∝τfγ, γ ∼ 1.4. The strength of coupling between bond kinetics and different diffusion timescales is estimated through various power-law relationships. Notably, acetamide-water hydrogen bond lifetime is linked to diffusive timescales through a single power-law over the entire water concentration studied. However, the relationship between diffusive timescales and the lifetime of acetamide-lithium complexes shows a sharp transition in behavior at 20 wt. % water, reflecting a change from vehicular diffusion below this concentration to structural diffusion above it. Our findings emphasize the critical importance of understanding bond dynamics within DESs, as they closely correlate with and regulate the molecular diffusion processes within these systems.