Changes In Moisture Content Research Articles

Experimental Investigation of Moisture Induced Offset Drifts on Plastic Packaged MEMS Sensor Devices

Encapsulated microelectromechanical measurement units are known to be sensitive to ambient humidity conditions, due to various effects caused by moisture diffusing into and out of the plastic packaging components. This paper focuses on investigating the effect that a change of moisture content has on the transient offset behavior of a packaged MEMS sensor by investigating the output signals of several test devices that only differ in their response to deformation of the MEMS core area. This comprises a novel method of experimentally analyzing the transient drift behavior of a MEMS caused by a deformation of the MEMS core area. This approach enables a back calculation of possible deformation shapes of the core area that explain the observed offset drifts in a given package. It was shown that the humidity response of a MEMS sensor is a strongly transient function that is not proportional to the uptake of water and can therefore significantly differ from their humidity performance at or close to a saturated state. Humidity performance tests that take only this state as point of reference for a performance evaluation cannot correctly estimate the humidity induced offset drifts. It was also shown that the moisture induced offset drifts can be traced back to a superposition of several deformation fields leading to several stages of the humidity response of MEMS sensors. Based on the example of the test devices it was shown that MEMS cores can be optimized to minimize the response of moisture effects. [2021-0212]

Ice-Water Phase Change Studies in Plastic and Non-Plastic Silts

This article presents experimental results and analysis of change in freezing characteristics of clays and silts with change in pH and moisture content in the pore structures. The plastic and non-plastic silts and clays in the cold regions undergo significant changes in thermal properties causing non-equilibrium thermal conditions which can lead to frost-heave, thaw-weakening, thawing-induced landslides, and mass wasting events. In geotechnical engineering, particularly in cold regions, a soil’s thermal properties play a large role in the design, functionality, and longevity of an earthen structure. The thermal properties of the soil will also govern the porous media phase changes influencing thermal hysteresis and heat capacity in soils. These variables will change with seasonal freeze–thaw cycles, which can lead to changes in a soil’s structure, fabric, density, moisture content, and strength over time. With global warming causing the temperatures to gradually rise over time, the rapidly varying seasonal freeze–thaw cycles are now becoming an issue in areas where the designs have relied heavily on the permafrost. This research study investigates the fundamental changes to freezing and thawing characteristics of plastic and non-plastic silts with changes in frost penetration rates (cooling rate); moisture content (liquid limit, plastic limit, and optimum moisture content); pH (2–7); and soil type with different percentages of fines content and specific surface area.

4D electrical resistivity tomography for assessing the influence of vegetation and subsurface moisture on railway cutting condition

Instability of slopes, embankments, and cuttings on the railway network is increasingly prevalent globally. Monitoring vulnerable infrastructure aids in geotechnical asset management, and improvements to transport safety and efficiency. Here, we examine the use of a novel, near-real-time Electrical Resistivity Tomography (ERT) monitoring system for assessing the stability of a railway cutting in Leicestershire, United Kingdom. In 2015, an ERT monitoring system was installed across a relict landslide (grassed) and an area of more stable ground on either side (wooded), to monitor changes in electrical resistivity through time and space, and to assess the influence of different types of vegetation on the stability of transportation infrastructure. Two years of 4-Dimensional ERT monitoring results are presented here, and petrophysical relationships developed in the laboratory are applied to calibrate the resistivity models in order to provide an insight into hydrogeological pathways within a railway cutting. The influence of vegetation type on subsurface moisture pathways and on slope stability is also assessed – here we find that seasonal subsurface changes in moisture content and soil suction are exacerbated by the presence of trees (wooded area). This results in shrink-swell behaviour of the clays comprising the railway cutting, resulting in fissuring and a reduction in shear strength, leading to instability. As such, it is proposed that on slopes comprised of expansive soils, grassed slopes are beneficial for stability. Insights into the use of 4-D ERT for monitoring railway infrastructure gained from this study may be applied to the monitoring of critical geotechnical assets elsewhere.

The Influence of Calendering on the Moisture Sorption Behavior of Electrodes for Lithium-Ion Batteries

Moisture is considered to be one of the most critical contaminants in Lithium-ion batteries (LIBs), as it impairs the electrochemical performance and poses high safety risks. To reduce the moisture in the cells below a critical level, electrodes and separators for LIBs need to be post-dried before cell assembly. However, the moisture adsorption, desorption and re-adsorption behavior of electrodes is defined by the chosen material system, the manufacturing route and the microstructure of the coatings. The microstructure, in turn, is significantly determined by the calendering step, which predominantly aims at increasing the specific density and consequently, the volumetric energy density of the electrode coatings. As the calendering step decisively changes the microstructure of the electrode coatings, it can be assumed that it accordingly must have an impact on the moisture sorption behavior of the electrodes during further processing. The sorption equilibrium of electrode coatings mainly depends on the surface of the particles, the sorption in the binder system and, to a certain extent, on the capillary condensation. LIB cathodes are most commonly manufactured with polyvinylidene fluoride (PVDF) as a binder. PVDF is very hydrophobic, which is why we can assume that the moisture sorption of these cathodes is fundamentally determined by sorption on the surface and, to a lesser degree, on capillary condensation. In contrast, the moisture sorption of LIB anodes produced with a carboxymethyl cellulose/styrene-butadiene (CMC/SBR) binder system is assumed to be mainly defined by moisture sorption of the very hygroscopic binder system. Changes to the surface should only have a small influence.Hence, it is expected that the impact of the calendering step on the moisture sorption is far more pronounced for the cathodes than for the anodes. To prove this theory and analyze the impact of the calendering step in detail, the influence of different densities on the moisture sorption behavior, microstructural properties and electrochemical performance of NCM622 cathodes with PVDF binder and graphite anodes with CMC/SBR binder system is investigated. Therefore, the electrodes are calendered to three different densities in dry room atmosphere, post-dried in vacuum and assembled into coin cells.Focusing on the cathode, after calendering an increasing moisture content is observed for increasing density, measured by Karl Fischer Titration and proved by sorption measurements. Although post-drying significantly reduces the moisture content of the cathodes, the course trend is still the same with the lowest moisture at a low density and the highest moisture at high density. Via SEM analysis, a rising amount of active material particle cracks is detected with increasing density. BET measurements show that this phenomenon is accompanied by an increasing specific surface area. Hence, the increased moisture uptake of cathodes with higher density can be mainly traced back to their higher specific surface area, caused by particle cracking during calendering. Further analytics display that the chosen post-drying parameters lead to an increase of cohesion strength for all cathodes, whereas the influence on the electrical resistance depends on the density of the cathode. The electrochemical testing shows that the increased electrochemically active surface area of the cathodes with higher density results in a good performance during formation and at lower C-rates. However, the reduced porosity lowers the ionic conductivity and leads to capacity losses at higher C-rates. [1]Concerning the anode, as expected, the influence of the calendering step on the moisture sorption is much smaller. Although the specific surface area of the anodes also increases with rising density, a significant increase of moisture is not observed. Hence, the influence of the changes in microstructure is overlapped by the hygroscopic binder system of the anodes. Post-drying increases the adhesion strength of all anodes, whereas the electrical resistance seems to decrease to a small degree. The electrochemical analysis of the anodes shows a deterioration of performance with increasing density, due to limitations of the ionic conductivity at lower porosities.Altogether, we will show that for NCM622 cathodes with PVDF binder, the moisture uptake increases with increasing density after calendering, whereas there is no change in moisture content at graphite anodes with CMC/SBR binder system. These findings make an important contribution to a better process understanding and consequently, improved moisture management along the entire process chain of Lithium-ion batteries.[1] F. Huttner, A. Diener, T. Heckmann, J. C. Eser, T. Abali, J. K. Mayer, P. Scharfer, W. Schabel, A. Kwade, Increased Moisture Uptake of NCM622 Cathodes after Calendering due to Particle Breakage, J. Electrochem. Soc. 168 090539 (2021), doi.org/10.1149/1945-7111/ac24bb, CC BY 4.0

Pulsed UV Integrated Infrared Dryer System for Orthosiphon Stamineus Herb.

The drying system is an important part for food and herbs preservation. Therefore, an effective drying system are needed to ensure the increase the shelf life of the food and herb without degrade its good nutrient and bioactive compound. In this study, Orthosiphon stamineus herb was used to dry using an Infrared dryer and combination of Pulsed UV light treatment + Infrared drying. Infrared drying involves transferring heat by radiation from a hot source to a lower-temperature substance that has to be heated or dried, meanwhile the pulsed UV light is a non-thermal treatment. The temperature of the heated element determines the peak wavelength of the radiation. The objective of this study is to design an infrared dryer system and analyze the quality of the dried herb. The Orthosiphon Stamineus have been dried using a 200W Infrared dryer system at 60°C. Total phenolic compounds and antioxidant capacity were determined using the Folin-Ciocalteu method and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assay measured using a UV/VIS Spectrophotometer. A moisture analyzer was used to look at the changes in moisture content, and a colorimeter was used to look at the colour changes. The result showed that drying Orthosiphon stamineus by using an Infrared dryer and combination of Pulsed UV light treatment + Infrared drying under 60°C has significantly affected the herbal leaves quality in terms of moisture content, colour properties, Antioxidant capacity, and Total phenolic content.

Climate impact on reinforcements in wooden members – effective hygro-expansion coefficients

ABSTRACT Wood is a hygroscopic material. The moisture content changes due to ambient climate variations e.g. according to erection and service time. The moisture content adapts first on the surface, and moisture gradient develop over the cross section and results in moisture induced stresses (MIS). MIS occur in addition to normal stresses for the load-bearing resistance and can affect reinforcements. To achieve a reliable evaluation of the safety level of reinforced timber structures, the present paper shows results from experimental test series on the load, moisture, and deformation investigation of structural glulam members reinforced with internal mechanical fasteners. Stepwise climate scenarios were applied and considered climates experienced by the structural timber member before or after reinforcement. For the estimation of the swelling and shrinkage behaviour, effective hygro-expansion coefficients have been determined. The coefficients are significantly lower than previously assumed in the standards. This enables engineers to estimate the impact on reinforcements which is not neglectable and reduces damage in a wide range of applications. The research results promote the use of wood by ensuring quality, performance, and aesthetics in timber constructions.

Improvement of Strength Characteristics of a Highly Plastic Expansive Soil with Fly Ash

Highly plastic expansive clays swell or shrink due to change in moisture content and they often have very low bearing capacity. Construction of engineering structures particularly pavements and lightweight buildings on problematic soils such as highly plastic expansive clays may create severe structural problems due to poor engineering properties of that kind of soil. This study focused on the influence of fly ash on strength properties of highly expansive clays which are problematic soils due to their undesirable engineering characteristics such as high plasticity index, liquid limit, swelling and shrinkage characteristics, and low bearing capacity. Atterberg’s limit tests and hydrometer tests were conducted to obtain consistency limits and grain-size distribution of the highly plastic expansive clay. Standard proctor tests for clay samples with different fly ash contents such as 10%, 15%, and 20% were performed to determine maximum dry densities and optimum water contents of the mixtures of clay and fly ash. The clay and fly ash mixtures were prepared at optimum water content and maximum dry density for unconfined compression strength (UCS) and California Bearing Ratio (CBR) tests. Effects of fly0ash content on the strength characteristics of a highly plastic expansive clay were investigated through unconfined compression and CBR tests. The experiment results showed that fly0ash is a promising additive to enhance strength characteristics of highly plastic expansive clays. An approximately 66% increase in UCS and CBR values was observed with the addition of 20% fly ash into the clay mixture in weight.

Physiological and omics analysis of maize inbred lines during late grain development.

There were significant differences in the change of moisture content and grain composition at the late stage of grain development among different maize varieties, but the regulation mechanism is not clear. To explore the key genes causing the variation in physiological traits of two typical maize inbred lines in late grain development. The grains at different development stages were selected as materials to determine the content of water, sucrose, starch and ABA. Transcriptomic and proteomic analysis of the materials were performed to screen relevant genes. The grain dehydration rate and the content of sucrose, starch and ABA were showed significant differences between two varieties in the late stage of grain development. The enrichment analysis of common differentially expressed genes (proteins) showed that most of the genes (proteins) were enriched in the extracellular region. The downregulated genes were mainly concentrated in carbohydrate metabolism and lipid metabolism, while the upregulated genes were mainly in response to stress. Furthermore, this study also identified many key candidate genes (dehydrin genes, pathogenesis-related genes, sucrose synthase and secondary metabolites related genes) related to late grain development of maize. The suggested genes related to late grain development of maize can be candidates for further functional study.

Precipitation Amounts Triggering Landslide Processes in the Western Part of the Nałęczów Plateau (Lublin Upland, Poland)

Abstract This study covers the western part of Poland’s loess Nałęczów Plateau (Kazimierz Dolny, Zbędowice). Mass movements in the Lublin Upland occur during periods of increased precipitation or after a snowy and cold winter. To date, there are no comprehensive studies on active (precipitation, hydrology, vegetation, land use, anthropogenic factors) or passive factors (lithology, slope angle) causing such geohazards in this region. This area’s formations are characterised by high sensitivity to even small changes in moisture content; thus, their geotechnical parameters deteriorate as a result of precipitation or rising groundwater levels. The calculations in this study were chosen to determine the time necessary for ground response to external factors, in addition to determining the impact of these factors on decreases in the factor of safety (FS). Based on calculations in GeoStudio software, the impacts of rainfall totals and duration on slope failure, interpreted as an event where the FS falls below 1.0, were analysed. Accordingly, the threshold rainfall value was determined as the total rainfall at the time of slope failure. The study’s results indicate that loess covers are characterised by average water permeability, relatively high internal friction angles and low cohesion, which, combined with high slope inclination, favour landslide formation even when the slope is only partially saturated. The most unfavourable stability conditions occur at the beginning of spring, indicating that loess stability is significantly affected by snowmelt and precipitation at the beginning of the vegetation season, as well as the occurrence of episodic intense precipitation during the summer.

Construction and calibration of a portable rain simulator designed for the in situ research of soil resistance to erosion

Land degradation caused by erosion processes is a widespread global problem. Rain simulators are one of the tools often used to determine the resistance of soils to erosion processes. The aim of this publication is to present the process of the construction and calibration of a small, portable field simulator which would be implemented in research studies designed to determine the changes in the soils’ shear strength parameters in forested areas (in situ) caused by a change in soil moisture content achieved by the rain simulation. The constructed simulator consists of a metal frame, sprayers (with specific nozzles), a sediment funnel/tray made of metal, water and a sediment collector unit, a water tank and pump, and a set of rubber hoses, manometer, valves, reducers, adapters and other supplementary equipment. The calibration was carried out by using the pluviometric method. The choice of nozzles was based on the criteria of low water consumption (losses), the Christiansen uniformity coefficient (CU) and the possibility of achieving specific downpour intensities for the investigated area. The further calibration of the device consisted of determining the raindrop diameter and the distribution of the rainfall when the simulator is positioned on the slopes (7° and 15°). The achieved rain intensity was 1.7–1.9 mm/min, with a CU of 92.23–93.70% for the raindrop diameters (D<sub>50</sub>) equal to 1.2 mm. The kinetic energy of the simulated rain (Ke) was 2.82∙10<sup>–6</sup> J. The constructed simulator proved itself to be in accordance with all of the given criteria, and it can successfully be implemented in research studies aimed at determining the resistance of forest soils to erosion processes, infiltration, and sediment yield.

Influence of moisture content, temperature, and time on free fatty acid in stored crude palm oil

Consequent to the importance of crude palm oil (CPO) to global food processing industries, and the need for quality assurance of CPO. A kinetic model that describes changes of free fatty acid (FFA) in industrially stored CPO has been developed. CPO FFA is a well-known indicator of the deterioration of CPO. The effect of initial moisture content, storage temperature, and time on CPO FFA have been investigated in this work. Specifically, statistical multi-regression models for changes in FFA and moisture content (MC) were developed at P-value < 0.05 or 95% confidence interval fence. It was found that CPO FFA increases with an increase in moisture content, temperature, and time in their linear term and in respect to decreases in their quadratic term, and interaction between moisture content and temperature. The CPO MC was also found to decrease with an increase in temperature and time and increases in the quadratic term of temperature. Although while the model for CPO FFA, based on Fisher's F-test: {mathrm{F}}_{mathrm{model}}(6.80)<{mathrm{F}}_{95mathrm{%}}(19.30), showed no lack-of-fit; that of CPO MC showed lack-of-fit, {mathrm{F}}_{mathrm{model}}(13.67)nless {mathrm{F}}_{95mathrm{%}}(4.39). Furthermore, based on inference from the statistical model, their kinetic models were also developed. While the CPO FFA kinetic, found to be a half-order kinetic model and its other auxiliary models showed a very good fit (R2 {0.9933–0.8614} and RMSE {0.0020–3.6716}); that of CPO MC was a poorly fitted first-order kinetic model (R2 {0.9885–0.3935} and RMSE {0.0605–17.8501}).

Use of Hydrological Models to Predict Risk for Rutting in Logging Operations

Using hydrological models with a high temporal resolution to predict risk for rutting may be a possible method to improve planning of forwarder trails or to schedule logging operations in sites with low bearing capacity to periods when soil moisture content is at a minimum. We have studied whether descriptions of rut variations, collected in 27 logging sites, can be improved by using hydrological data, modeled by Swedish HYdrological Prediction for Environment (S-HYPE). Other explanatory variables, such as field-surveyed data and spatial data, were also used to describe rut variations within and across logging sites. The results indicated that inclusion of S-HYPE data led to only marginal improvement in explaining the observed variations of the ruts in terms of both “rut depths” within the logging sites and “proportion of forwarder trails with ruts” across the logging sites. However, application of S-HYPE data for adapting depth-to-water (DTW) maps to temporal changes of soil moisture content may be a way to develop more dynamic soil moisture maps for forestry applications.

Investigation of Resilience Characteristics of Unbound Granular Materials for Sustainable Pavements

In this study, a comprehensive laboratory testing program was designed to study the resilience characteristics of unbound granular materials (aggregate base coarse) using the repeated load triaxial test (RLTT). During the experimental program, the resilient modulus of unbound granular material was examined using different moisture content levels, material gradation using Fuller’s equation, and stress levels. The results show that the moisture content, material gradation, and stress level have a major influence on the resilient modulus of unbound granular materials. Furthermore, a linear model has been developed between moisture content and the resilient modulus. The model significantly predicts the change in resilient modulus by changing moisture content. The study also aimed to improve the modified Uzan model by adding the effect of moisture content. An improved modified Uzan stress moisture model has been developed, which shows a strong relationship between the resilient modulus, stress, and moisture content. This study can be used as a benchmark for validating other numerical data.

Effect of Plasma Bubbling on Textural and Engineering Properties of Ready-to-Eat Pearl Millet Flakes and Puffs

Ready-to-eat (RTE) millet grain flakes and puffs are gaining importance in the modern era because of their nutritional and health benefits. In this work, air plasma has been generated and bubbled into pearl millet during soaking, followed by analyzing its flaking and puffing characteristics. The voltage 180, 200, and 220 V with airflow rates of 10 and 12 lph for 1 and 2 h was exposed to treat pearl millet samples. An increase in conductivity, total soluble solids (TSS), and drop in pH of the soaked medium was observed with the bubbling of plasma. The plasma bubbling exhibited an improvement in the pearl millet’s flaking and puffing properties. The noteworthy changes ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P &lt; 0.05$ </tex-math></inline-formula> ) in expansion volume, bulk density, color, moisture content, crispiness, and hardness were observed in flaked and puffed samples. An increase in the expansion ratio (ER) of pearl millet flakes and puffs from 4.2 to 8.3 and 4.9 to 9.5 decreases in bulk density of flakes and puffs from 0.36 to 0.11 and 0.14 to 0.06 kg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively, was noticed with the plasma bubbling. The textural properties like the crispiness of the flakes and puffs elevated, and hardness was reduced with the given treatments. The decrement in yellowness index (YI) and increase in whiteness index (WI) was observed in both flaked and puffed samples with the rise in exposure time. The synergistic effect of plasma reactive species in combination with hydration aids in improving grain properties and helps in diversifying the utilization of millet grains.

Study on the Expansion Law of Dry Shrinkage Cracks in Silty Clay.

Fracture characteristics are the basis of silty clay fracture research, and its quantitative description is helpful to explore the engineering properties of silty clay. The silty clay samples with different moisture contents and different aspect ratios were prepared by the controlled variable method for the drying shrinkage test. The crack image processing and crack feature extraction were performed by PS and IPP software, and the relationship between the crack propagation characteristic parameters and the change in humidity and sample moisture content during drying shrinkage were analyzed to explore the crack development law. The results show that under the continuous action of the environment, cracks were generated at the initial high temperature (46 °C). When the temperature changed from a high temperature (46 °C) to a low temperature (27 °C), the moisture content decreased faster, and the crack developed rapidly. Later, from low temperature (12 °C) to high temperature (46 °C), the water content and crack parameters remained basically unchanged; the cracks of the samples with a high moisture content appeared early, developed rapidly, and damaged seriously. When the aspect ratio was 6:1, the crack developed vertically, and when the aspect ratio was less than 6:1, the secondary crack was about 90° from the upper crack.

Qualitative comparison of elemental concentration in soils and other geomaterials using FP-XRF.

Field portable X-ray fluorescence (FP-XRF) has tremendous potential in geoenvironmental engineering as a qualitative assessment tool. Identification of the elevated concentrations of the selected elements (Cr, Cu, Mn, Ni, Pb, and Zn) in various geomaterials like soil-like-material (SLM), incinerated bottom ash (IBA), construction and demolition waste (CDW), zinc tailings (ZT) and fly ash (FA) was performed by FP-XRF and compared with the local soil–Delhi silt. Comparably higher concentrations (mg/kg) of Cr (401.0), Cu (499.0), Pb (532.0), Zn (608.0) in SLM, Cr (195.0), Cu (419.0), Ni (93.0), Pb (931.0), Zn (771.0) in IBA and Cr (195.0), Cu (4000.0), Pb (671.0), Zn (7122.0) in ZT were observed. CDW and FA showed similar concentrations range as in local soils. FP-XRF was also used in-situ on local soil at 11 sites to examine its ability to identify the elements with significant variations in concentrations. The results showed high variability in Cl and S concentration values across the 11 sites attributed to the changing moisture content and dissolved salts. The concentration range for the remaining elements were similar at all sites. The verification of the detected elements through visual inspection of the spectrum was also carried out.

STUDY OF SORPTION PROPERTIES OF QUINOA SEEDS

The paper provides an analysis of the current state of the quinoa seed market in the world and the prospects for its production in Ukraine. The main producers of quinoa are Peru, Bolivia and Ecuador. Due to its rich chemical composition, quinoa seeds are rapidly gaining popularity. Ukrainian enterprises use quinoa grain for the production of various products and semi-finished products. Quinoa seeds are attracting increasing attention worldwide not only for their nutritional and functional properties, but also for their ability to grow in adverse climatic conditions. Increasing demand and rising global prices for quinoa is encouraging producers to adapt the crop to low altitudes and grow it in arid conditions. Breeders and scientists of different countries are actively working on the adaptation of quinoa seeds to growing in different regions, which has an important impact on food security. Quinoa grain imported to Ukraine requires long-term storage without weight loss and quality deterioration. An important influence on the state of grain mass during storage is its hygroscopicity, that is, the ability to sorb and desorb water vapor. Knowledge about the hygroscopic properties of grain is of practical importance for the scientific justification of the choice of rational modes of storage and post-harvest processing. The main characteristic of the hygroscopic properties of grain materials is the equilibrium moisture content, therefore, its determination is an important step in preserving grain quality. The equilibrium moisture content of quinoa grain was determined. The research was carried out by the generally accepted tensimetric method in the range of air temperatures ±(5...25)°С and relative air humidity 40...80%, which simulate the conditions of grain storage and correspond to long-term average data, corresponding to warm and cold seasons in Ukraine. The nature of the change in the equilibrium moisture content of quinoa grain depending on the temperature and relative humidity of the air has been established. As the relative humidity increases and the ambient temperature decreases, the equilibrium moisture content of the quinoa grain increases. Empirical coefficients were determined and an equation was proposed that describes the dependence of the equilibrium moisture content of quinoa grain on the parameters of the surrounding air, which can be used to predict its change. The obtained data are of practical importance for the selection of high-quality storage regimes for quinoa seeds.

Equations for Calculating the Thermal Conductivity of Capillary-Porous Materials with over Sorption Moisture Content

This article is the result of the authors’ work on the method of calculating the effective thermal conductivity of moist capillary-porous materials used in wall partitions. The proposed methodology was developed based on the theory of generalized conductivity and geometric modeling of the structure. Materials are considered as heterogeneous ternary systems consisting of a solid skeleton, gas and liquid, and all components are simultaneously taken into account in the calculation. In this work, additional equations are constructed that allow calculation of the effective thermal conductivity of capillary-porous materials with over sorption moisture, thus extending the scope of application of the method to the entire possible range of changes in moisture content. The details of calculating the thermal conductivity of moist capillary-porous materials are demonstrated using experimental data for wall ceramics samples. It is shown that the proposed equations are capable of predicting the thermal conductivity of moist capillary-porous materials with sufficient accuracy. Knowledge of the thermal conductivity of materials in conditions of their actual moisture is fundamental in the sustainable design of new buildings as well as thermo-renovation and dump protection of historic ones.

Soil moisture dominated the temporal dynamics of litter moisture content in subtropical forests: a 7-year observation in south China

Study regionDinghushan watershed, China. Study focusThe dynamics of litter moisture content play an important role in understanding the forest’s internal environmental changes, forest fire forecast and prediction of general forest health and so on. These characteristics have not been extensively analyzed in lower subtropical China and therefore, three typical subtropical evergreen forest ecosystems, Pinus massoniana coniferous forest (PF), mixed conifer-broadleaf forest (CBF), and monsoon evergreen broadleaved forest (MBF), were chosen to explore the changes of the litter moisture content and its response to environmental factors. New hydrological insights for the regionOver a 7-year observation period, the mean annual litter moisture content was 72.0 ± 7.3%, 87.9 ± 11.3%, and 100.5 ± 15.7% for PF, CBF, and MBF respectively. The litter moisture content increased while the litter standing mass decreased after vegetation restoration. The litter moisture content in the three forests during the wet season was substantially higher than that in the dry season. Compared to the soil layer, the coefficient of variation of the litter moisture content during the dry and wet seasons was higher as compared to the topsoil (0–30 cm) water content, indicating the litter layer was more sensitive to changes in external environmental factors. Further analysis revealed that soil water content was the dominating factor controlling the dynamics of litter moisture content both during the dry and wet seasons. Analyses of the litter moisture can be very useful in forests around the world as a guideline in indicating the change in a forest’s environment.

Effect of process variables on some quality attributes of instant ‘Akara iwe’-a cassava based fried snack from grits

A Box-Behnken (three-factor) response surface design was utilized to determine effect of grits rehydration level (35–45%), frying temperature (155–175 °C) and frying time (7–13 min) on some attributes (moisture, oil, textural parameters and colour) of instant Akara iwe, a cassava based fried snack and optimize the process. Sensory evaluation of the optimized sample to measure its degree of acceptability was conducted including comparison with Akara iwe from raw cassava mash. Frying temperature, frying time and grits rehydration level had significant (p<0.05) effect on moisture content, cohesiveness, springiness and colour change of instant Akara iwe. Based on desirability (71%) index, the optimal process variables for instant Akara iwe were 38% grits rehydration level at 169 °C for 9 min. The oil content of the optimized Akara iwe samples differ significantly (p<0.05) from the reference sample with the former retaining less oil. Similarly, optimized instant akara iwe had higher hardness (789.23 N) and chewiness (382.2 N) values than the reference samples and were significantly (p<0.05) different. Panelists preferred the optimized samples in terms of colour, oiliness and aroma.