Critical Moisture Research Articles

An Environmentally Benign Electrolyte for High Energy Lithium Metal Batteries.

A hybrid electrolyte comprising a high content of H2O for a lithium metal cell is reported. At high LiFSI salt concentration, the N-methyl-N-propyl-piperidinium bis(fluorosulfonyl) imide (PMpipFSI) electrolyte can tolerate up to 1 M H2O addition without sacrificing its redox stability on both lithium nickel manganese cobalt oxide (NMC) cathode and lithium metal anode. Molecular dynamics simulations revealed the underpinned mechanism that, at high salt concentrations, H2O molecules are embedded in the Li+, PMpip+, and FSI- bulk as a structural material with a strong solvation with Li+ and are orderly distributed at the surface of both electrodes. This electrolyte eliminates the critical moisture controls required for the state-of-the-art (SOA) carbonate/LiPF6 electrolyte, electrode, separator and cell assembly, thus significantly reducing the cost of the mass production of the batteries.

Quality Formation of Adzuki Bean Baked: From Acrylamide to Volatiles under Microwave Heating and Drum Roasting.

Baked adzuki beans are rich in tantalizing odor and nutritional components, such as protein, dietary fiber, vitamin B, and minerals. To analyze the final quality of baked beans, the acrylamide and volatile formation of adzuki beans were investigated under the conditions of microwave baking and drum roasting. The results indicate that the acrylamide formation in baked adzuki beans obeys the exponential growth function during the baking process, where a rapid increase in acrylamide content occurs at a critical temperature and low moisture content. The critical temperature that leads to a sudden increase in acrylamide content is 116.5 °C for the moisture content of 5.6% (w.b.) in microwave baking and 91.6 °C for the moisture content of 6.1% (w.b.) in drum roasting. The microwave-baked adzuki beans had a higher formation of the kinetics of acrylamide than that of drum-roasted beans due to the microwave volumetric heating mode. The acrylamide content in baked adzuki beans had a significant correlation with their color due to the Maillard reaction. A color difference of 11.1 and 3.6 may be introduced to evaluate the starting point of the increase in acrylamide content under microwave baking and drum roasting, respectively. Heating processes, including microwave baking and drum roasting, for adzuki beans generate characteristic volatile compounds such as furan, pyrazine, ketone, alcohols, aldehydes, esters, pyrroles, sulfocompound, phenols, and pyridine. Regarding flavor formation, beans baked via drum roasting showed better flavor quality than microwave-baked beans.

Effect of carbonation and ultrasonication assisted hybrid drying techniques on physical properties, sorption isotherms and glass transition temperature of banana (Musa) peel powder

Banana peels (Cavendish and Nay poovan) in ripe and raw form were dried using tray drying (T), microwave (M), microwave-convection (MC) and freeze drying (F) with ultrasonication (U) and combined treatment of carbonation and ultrasonication (CU) as pretreatments. SEM analysis showed microscopic channels in samples after U treatment, which were more ravine after CU. Based on bulk density, tapped density, porosity, angle of repose, colour parameters, viscosity, CU + F was found best drying combination followed by CU + MC. For selected samples, relative water sorption changes induced by U and CU were positive as the sorption surface area increased after given pre-treatments. Peleg model fitted best to experimental data for sorption studies. The water plasticizing effect of U and CU treatments on glass transition temperature (Tg) was predicted using Gordon-Taylor model. State diagram predicted critical moisture content (Xc), 0.106 kg H2O/kg dry matter and critical water activity (awc), 0.525 at 16 °C.

Assessment of moisture and mould of hempcrete and straw panels

At present buildings contribute a third of total greenhouse gas emissions. There is a need for sustainable solutions and natural materials, which offer low-embodied energy and their low impact has a promising potential as construction alternatives. Hempcrete is a lightweight insulation material, which provides natural, airtight, and vapor-permeable insulation. Straw panels are also natural construction materials and they consist of extruded wheat straw and are surrounded with recycled paper on all sides. There are some risks, which can be associated with the use of such materials - infestation, biological degradation, presence of moisture, and structural degradation. The aim of the study is to determine the critical moisture level and mould resistance of hempcrete and straw panels. The results of this study are valuable to both scientists and structural engineers.

Stress relaxation properties of bananas during drying.

Bananas' mechanical properties are affected by the ripening and the drying processes since they induce profound microstructural changes. In this study, first, the interacting effect of the ripening and the drying processes on the mode of viscoelastic behavior of bananas was investigated. Second, the stress relaxation properties of fully ripe bananas were measured as a function of the hot air drying conditions. Finally, the two-element generalized Maxwell model was fitted to the experimental data. Thus, this study clarified the dependence of the mode of rheological behavior on both the ripening stage and the moisture content. It showed that bananas start softening at the onset of the drying when the fruit moisture content is high. The softening is reversed at a critical value, at which the bananas start regaining stiffness with further moisture reduction. The critical moisture content value decreases with ripening from 1.4g/g solids for green bananas (5-11% Brix percentage) to 1.23 g/g solids for half-ripe bananas (15-20% Brix percentage) and eventually vanishes when the bananas are fully ripe (25-31% Brix percentage). The stress relaxation properties measured with fully ripe bananas substantiated the initial findings on the influence of the ripening stage on the mode of rheological behavior. The relaxation moduli displayed a decreasing trend with decrease in the moisture content for 40, 60, and 80°C drying temperatures and decayed with time as expected for viscoelastic bodies. Lastly, the two-element generalized Maxwell model fitted well to the experimental data with the root mean square error varying between 0.06 × 10-5 and 90.6 × 10-5 MPa.

Analysis of states of water in cashmere fibers and utilizing water as molecular probe for pore size distribution

Fundamental understanding of cashmere–water interaction is a critical part both for the manufacturing of cashmere processing and the development of cashmere-based heat-moisture management textiles. Based on the unfreezable threshold and hygroscopic properties, different types of water in cashmere and the interaction between water and fibers were investigated by using low-temperature differential scanning calorimetry (DSC) and dynamic water vapor sorption (DVS), the pore size distribution in cashmere were also determined according to the Gibbs−Thomson effect of the bound water probe. The amount of free water and non-freezable water was experimentally detected, and the critical moisture regain of these two types of water was 37.2%. The pore size distribution of cashmere showed that most pores were less than 60 nm in diameter. The monolayer moisture content of cashmere accounted for up to 17.26% (corresponding to 50 °C) of the non-freezable water, which were evaluated though the Brunner–Emmet–Teller (BET) theory. The net isometric heat of desorption is calculated from the partially overlapping isotherms at different temperatures, which break through the limitation of the Clausius–Clapeyron equation, and the boundary of monolayer water and multilayer water were identified by the curve of isosteric heat.

SUBSTANTIATION OF ENERGY EFFICIENT REGIMES OF DRYING PRODUCTS FRACTIONAL PROCESSING OF ALFALFA

Shortage of quality feed significantly slows down the production of livestock products in Ukraine. One of the ways to overcome the crisis in the production of feed is the use of new high-energy feed, including the products of fractional processing of alfalfa. For the successful implementation of the skin type of feed, including the products of fractional processing of alfalfa, there should be an opportunity to create their reserves, feed should be canned for successful storage. The best way to preserve food is to dry it. Energy efficiency of the drying process, ie loss of nutrients, energy costs for the implementation of the process, etc. It depends on the method and its mode parameters. In this case, it is proposed to carry out the drying process in a thick layer of alfalfa pulp by active ventilation with heated air. To determine the rational parameters of the process, such as layer thickness, air flow, drying time and patents to conduct theoretical and experimental studies. Alfalfa pulp, like most wet plant materials, belongs to the capillary-porous bodies. The drying blood of these bodies has two distinct periods: constant and decreasing speeds (or the first and second drying periods). The moisture content of the material at which the transition from the first to the second period is called critical. As a result of theoretical research has obtained a dependence that determines the total duration of the drying process on a number of parameters, including initial, critical, equilibrium and final moisture content. To determine these coefficients, as well as to check the adequacy of the obtained dependence, experimental studies were conducted on a special installation. The main elements of the experimental setup are a fan, electric heater, containers with mass, shut-off, control and measuring equipment. According to the results of experimental research, graphical dependences of drying speed and process duration on regime parameters are obtained.

Дослідження кінетики сушіння підготовленого борошна пшеничного

Introduction. Processing of grain raw material with influence on starch or albumens by application of heat treatment creates the variety of functional properties of a product and is perspective in the modern terms vital functions of man. Research methods and methods. The flour obtained from wheat of the Ascanian wheat and from wheat of the soft varieties: Sophia ("sweet wheat"), Blond (soft) and Chornobrova (enriched with micro- and macronutrients) were used in the study. Thermal modification of flour samples was carried out in a convective manner. The control sample for determining the quality indicators is obtained in industrial conditions, extruded wheat flour produced by LLC "AS groups, LTD". Research results. The obtained kinetic dependence shows the gradual loss of moisture standards with different speed which accordingly influences on duration of drying. The moisture content of the drying agent most affects the intensity at the initial stage of the constant drying rate. With an increase in the moisture content of the coolant, the period of constant drying increases and the amount of evaporated moisture increases during this period. With the subsequent removal of moisture from raw materials, the degree of influence of this parameter on the intensity decreases. The nature of the drying curves is the same and the recommended process for obtaining modified flour is the process duration of 300 minutes or 5 hours. It was determined microscopically, that the samples of dried wheat flour have a purpose and are partially destroyed by starch granules and amorphization of biocomposite materials. Based on the data on the kinetics of drying flour samples, the kinetic coefficients and values of the critical moisture content for drying wheat flour were calculated, which is 1.18-1.30 %. It was determined that for the sensorial indicators the obtained samples have indicators characteristic of the varietal characteristics of wheat, from which the flour was taken. In terms of physical and chemical parameters, the modified wheat flour samples are not inferior to the well-known industrial sample of extruded flour. Conclusions. Use of flour, obtained from the wheat with different correlation of amilose and amylopectin, positively influences on a technological process and allows to extend the assortment of modified starch products, and accordingly, food products. Kinetics of the convective drying standards of the flour is investigated. Researches showed that a it is physically modified flour obtained from the different sorts of the soft wheat is not inferior in quality to the extruded wheat flour.

Modeling of mass transfer processes during dehydration of air-dried fish

The study addresses the problems of the Fisheries industry development in the Murmansk region. It has been acknowledged that the percentage of the frozen fish in the output of hydrobionts food products is about 90 %. The focus areas for the Russian Fisheries industry are the increasing share of products with high added value and the development of the domestic consumer market of fishery products. It has been found that the air-dried and dried fish products with defined organoleptic properties is traditionally in strong demand with the population. However, the range of air-dried and dried fish products available for the consumers is rather limited. Moreover, there is a very small part of air-dried and dried fish in the total volume of hydrobionts food products. It is possible to increase the efficiency of air-dried and dried fish production by using the scientific-based process solutions, which allow to reduce the production costs and improve the consumer properties of the finished products. This paper presents the aspects of generalization of the dehydration processes in the production of dried, air-dried and smoked fish. A link between the initial, critical moisture content of fish and the potential conductivity of mass transfer coefficients has been established. A mathematical relation for calculating the duration and modeling the kinetics of drying processes in production of dried and air-dried fish has been determined. The equations for calculating the water diffusion coefficients in the critical points of the kinetics curve have been obtained. The combined use of the received patterns allows to model the dehydration processes when producing the air-dried and dried fish products, calculate the drying time, determine the moisture diffusion coefficients and build dependencies of water distribution in the thickness of the processed object.

Potential of extrusion-blown poly(lactic acid)/cellulose nanocrystals nanocomposite films for improving the shelf-life of a dry food product

The potential of neat poly(lactic acid) (PLA) and PLA/cellulose nanocrystal (CNC) blown films in extending the shelf-life of crackers, a moisture-sensitive food product, was assessed. Product’s shelf-life, i.e., the time required by the crackers to reach its critical moisture content (CMC) of 8%, was determined experimentally from moisture content versus storage time plots at a constant temperature (25 °C) and various conditions of relative humidity (RH). Neither crackers within PLA nor PLA/CNC packages reached the CMC when stored below 50% RH at 25 °C, indicating that crackers packaged in both films were shelf stable at these conditions. Above this RH, the crackers inside both packages reached the CMC at different times, however crackers in CNC-based packages had approximately 40% longer shelf-life than those in neat PLA package. The shelf-life of crackers packaged in films predicted from various simulation mathematical models supported the experimental data that the crackers packaged in the PLA/CNC films had higher shelf-life compared to those packaged in neat PLA films; clearly demonstrating the potential of CNC-based films to extend the shelf-life of dry-foods.

Shelf-life assessment of energy banana bar using acceleration method with critical moisture content approach

The shelf-life of the product need to be evaluated according to the commercialization of the product. Shelf-life assessment of the product can be done using acceleration method (Accelerated Shelf-life Testing) with critical moisture content approach. This research used the acceleration method to predict the expired date of the energy bar based banana. This method required the data such as initial water content, critical moisture content, solid weight of the product, surface area of the packaging, permeability water vapor of the packaging, saturated water vapor pressure, and slope of the sorption isotherm curve. The result showed that the shelf life of banana bar products that was packaged using aluminium foil, aluma, and metalized plastics consecutively for 511.15; 458.72; and 80.95 days based on the acceleration method with the critical moisture content approach.

Impact of Moisture Content on the Brittle-Ductile Transition and Microstructure of Sandstone under Dynamic Loading Conditions

Rockburst frequently occurred in an unstable or violent manner, which posed great safety risk and economic loss in deep underground engineering. The water injection into rock stratum was one of the most effectively ways to reduce rockburst by weakening rock mechanics. However, the moisture content was an important index related to rock mechanical properties. Many previous studies focused on the relationship between the moisture contents and macromechanical properties of rock materials under static load and seldom explored the impact of moisture variation on the mechanical properties and brittle-ductile transition characteristics of rock materials under dynamic loads. In this paper, we studied the dynamic mechanical properties of sandstone with different moisture contents under the same strain rate by the Split Hopkinson Pressure Bar (SHPB) experimental system. The relationship between dynamic mechanical properties of sandstone and moisture content was studied, and a dynamic ductility coefficient was proposed, which could be determined by the ratio between the peak strain and the yield strain. Then, it was used to assess the critical moisture content of the brittle-ductile transition of the sandstone. Through scanning electron microscopy (SEM) examination, the microstructure of sandstones with different moisture contents was inspected at magnifications of 500, 2000, and 5000 times, respectively. We showed that as the moisture content increased, the dynamic peak strength and elastic modulus decreased at different degrees, whereas the dynamic peak strain and ductility coefficient exhibited a nonlinear increase, respectively. When the moisture content reached 2.23%, the variation ratio of the dynamic ductility coefficient commenced to increase obviously, indicating that the sandstone began to transit from brittle behavior to ductile behavior. When the sample magnification was 500 times, the microstructure of the sandstone samples with zero and 2.01% to 2.40% moisture content mainly displayed the step pattern and river pattern, respectively, showing that the damage mode was brittle fracture. When the moisture content ranged from 2.49% to 2.58%, the microstructure of the sample included a large number of dimple clusters with local snake patterns and belonged to ductile fracture. When the sample magnification was 2000 and 5000 times, the microstructure was mainly brittle fracture with a moisture content lower than 2.23%. The microstructure of the sample with moisture content of 2.23% exhibited brittle-ductile composite fracture form, whereas others exhibited obviously ductile fracture. These characteristics were fundamentally consistent with the results reflected by the dynamic ductility coefficient. Our findings could provide a theoretical basis for mitigating coal and rock bursts by injecting water methods in underground coal mines.

CLT construction without weather protection requires extensive moisture control

This study examines how cross-laminated timber (CLT) constructions, including joints, connections and attachment points, are affected by precipitation during construction. The case studies are based on moisture content measurements and material sampling as well as microbiological analysis during the structure’s construction stage. The study does not include remediation control. The field measurements show microbiological growth in all buildings and almost all floor structures that were investigated. Of a total of 200 measuring points analysed, half had mould growth and around a third had moderate or extensive growth. The moisture content measurements for one of the locations with the largest percentage of elevated or high moisture content was at the top of the floor structure in the bottom gap between timbers in the CLT top layer. This is one example of several materials or construction components where there is limited possibility of dry out. Based on the outcome, it would appear difficult, or impossible, to avoid the appearance of microbial growth during construction with CLT without weather protection. Previous studies indicate that microbiological analysis of CLT is extremely rare in both laboratory and field studies, which implies that there are obvious shortcomings in the scientific work. The fact that mould growth is often invisible needs to be disseminated, especially in practical studies. However, there seems to be a good level of awareness in the literature that theoretical studies often conduct mould growth risk evaluations. There do not appear to be any moisture safety assembly methods or solutions for CLT construction that do not have weather protection or a declaration of the critical moisture conditions for CLT products.

Experimental Study on Critical Moisture Content of Octadecylamine Modified Expansive Soil

Taking weak expansive soil as the research object, octadecyl primary amine (octadecylamine) was mixed into remolded expansive soil as a water repellent, and modified samples with different octadecylamine content and initial moisture content were configured. The dripping water penetration time method was used to determine the water repellency grade of the modified expansive soil, and the critical moisture content test of the modified expansive soil was carried out to analyze the relationship between different octadecylamine content and the initial moisture content of the expansive soil. The results show that with the increase of the initial moisture content, the water repellency of the modified expansive soil first increases and then decreases. When the octadecylamine content is 0.8%, the limit moisture content is 33.33%, and the peak moisture content is 29.51%. The bottom water content is 0%, and its interval value is 3.78 times larger than when the octadecylamine content is 0.2%.he above research results can provide a test basis for the engineering application of modified expansive soils.

Investigation on the improvement of the combustion process through hybrid dewatering and air pre-heating process: A case study for a 150 MW coal-fired boiler

In this study, a parametric advanced exergy analysis was conducted for the waste heat recovery of a pulverized coal-fired power plant. In this aim, a new attainable ideal and the technically available unavoidable case for the combustion process were identified. Under the identified improved potential term, different unavoidable cases were parametrically investigated for the hybrid dewatering and air preheating process to improve the combustion process. In this aim, different removed moisture contents, air preheating conditions, and effectiveness of both internal and external heat exchangers were thermodynamically evaluated in terms of the combustion process. The improved potential was calculated as 74.4% for the whole combustion system. The critical moisture removal ratio was calculated as 20%. The effects of rehabilitation on improved potential were found as 2.80 points per 1% of effectiveness increase for the self (internal) heat exchangers of the boiler, 1.68 points per 1% of effectiveness increase for HE-I and HE-II (external heat exchangers), and 0.62 points per 1% increase of dewatered moisture ratio. Besides, a saving of about 29.54% was determined in fuel consumption for the most appropriate unavoidable condition.

Low-temperature oxidation and self-heating accelerated spontaneous combustion properties of a Yima formation bituminous coal with various moisture contents

By thermogravimetry (TG) experiments, evolution behaviors and properties of thermal oxidation processes at low temperature (< 230.0 °C) of a bituminous coal with five moisture contents were investigated. A novel Acceleration Temperature Point Method (ATPM), defined as the transition point from low-temperature oxidation to rapid self-sustained heating-up period, was proposed to determine the role of moisture content in accelerating such process. Results show that segments of water evaporation and gas desorption dominate in stage 1 (65.0–150.0 °C), while segments of generation of coal-oxygen complex and structure oxidation dominate in stage 2 (150.0–275.0 °C). In the moisture range of 9.16–12.06%, the promoted effect of physical desorption capacity becomes weak with increasing moisture content. This is owing to five aspects: the equilibrium of vapor pressure and wetting capability of physically bound water, the change of mass and heat transfer between gas phase (water vapor)-condensed phase (bulk coal particle), the diffusing effect of gaseous water, the heat from dissolving and swelling of gaseous water into bulk coal pores, and the heat of pyrolysis derived from coal particles. Taking Acceleration Temperature Point (ATP) as a barometer to evaluate the spontaneous combustion susceptibility, the critical moisture content of Gengcun bituminous coal is 9.16%.

Kinetic modelling of acrylamide formation during the frying of potato chips

The effect of potato tuber composition, frying time and temperature on acrylamide formation in potato chips was investigated and a mathematical model of the kinetics of acrylamide formation is provided. Moisture-temperature–time profiles were obtained for potato slices during frying to enable the determination of the ‘effective’ reaction time by identifying the critical moisture content (6% dwb) for acrylamide formation to commence and using dehydration curves to calculate subsequent frying time to finished product moisture content. The chemical kinetic model conformed to the following rate equation over a one hundred-fold range of acrylamide concentrations:d[acryl]dt=k1glucoseasn+k6[fructose][asn][TAA]where [TAA] represents total amino acid concentration. The timescale of the frying process meant that the chemical reactions were all in their initial rate phase. Kinetic parameters confirm that the fructose-dependent reaction (caramelization) contributes twice as much acrylamide as the reaction of glucose (Maillard reaction).

Effects of Moisture and Amphiphilic Compounds on the Oxidative Stability of Microwave‐Treated Corn Oil

AbstractEffects of moisture and amphiphilic compounds, including oleic acid, lecithin, and monoacylglycerols (MAGs), on the oxidative stability are evaluated in microwave‐treated corn oil. Moreover, the physical properties including critical micelle concentration (CMC) and moisture content are determined in oils treated by microwave irradiation. The CMC of lecithin and moisture content of oils decreases remarkably, whereas the temperature of the oil increases rapidly with microwave irradiation. The addition of lecithin results in increased moisture content significantly in the edible oils, whereas oleic acid and MAGs do not exhibit these effects. Primary oxidation products in all the oil samples increase, despite the type of amphiphilic compounds used. Corn oil containing oleic acid and samples with lecithin exhibits lower and higher p‐anisidine values (p‐AV), respectively. Remarkably high moisture content in corn oils containing lecithin may contribute to the formation of volatile compounds and high p‐AV. Collectively, moisture and amphiphilic compounds affect the degree of lipid oxidation in microwave‐irradiated bulk oils.Practical application: A microwave oven is an irreplaceable home appliance and is widely used in households nowadays. Effects of amphiphilic compounds and moisture on the oxidative stability are evaluated and it is found that the amphiphilic compounds in lipids affect heat transfer and oxidative stability of oils. The results of this study can provide fundamental insights into lipid oxidation in edible oils, and can provide a direction to the food industry with respect to the development of more efficient and safe methods for the preparation of microwavable foods.

The Drying Rate of Chlorella pyrenoidosa Using an Oven in Bioethanol Production

The production of bioethanol from microalgae goes through several stages, including cultivation, harvesting, drying, storage, and conversion to bioethanol. Nearly 40% of the total energy consumed in the bioethanol production from microalgae is from drying. This research aims to study the drying rate model of Chlorella pyrenoidosa using an oven. The drying is carried out at the temperatures of 50, 60, and 70 oC. The initial moisture content of Chlorella pyrenoidosa was 317.798% dry weight. The results showed that at the temperatures of 50, 60, and 70 oC, the critical moisture content was 9.108, 7.583, and 6.93% dry weight, while the equilibrium moisture content was 3.172, 3.158, and 3.109% dry weight. The most optimal drying is at 70 oC and the drying rate gets faster as the temperature does too. The Page model is better at describing the drying rate of Chlorella pyrenoidosa using an oven than the Newton model. The drying speed constants (k) were 0.00056, 0.00061, and 0.00208, at 50, 60, and 70 oC, respectively.

DMSO as new, counterintuitive excipient for freeze-drying human keratinocytes

DMSO is widely used as powerful cryoprotectant for the storage and transport of frozen cells. Beyond this established application of DMSO, we could now show that it has also promising lyoprotectant effects in the field of lyophilisation of therapeutic cells. Freeze-drying of HaCaT keratinocytes in 10% HES, 5% HE and in presence of DMSO led to an increase in cell membrane integrity from 25.3 ± 2.7 % without DMSO to 41.4 ± 4.3 % with 2% DMSO, as determined by trypan blue exclusion. Interruption of the lyophilisation cycle at different sampling points showed a rapid decrease of cell membrane integrity below a critical residual moisture content. DMSO was able to stabilise cell membranes below this moisture level up to a final residual moisture content of less than 1%. Furthermore, DMSO increased the total protein content of cells after freeze-drying and subsequent SDS PAGE analysis indicated that certain abundant proteins were better preserved with the use of DMSO. Owed to its low vapour pressure, a significant part of DMSO is not removed during freeze-drying and remains as plasticiser in the lyophilised cake. However, a Tg above 60°C for 2% DMSO indicates that samples can still be stored at temperatures of 2-8°C. Also, no macroscopic or microscopic collapse can be observed by SEM or BET measurements and DMSO addition leads even to more elegant cakes with reduced cake cracking. With a better preservation of cell membranes and cellular structures, DMSO can contribute to the still unsolved problem of freeze-drying cells of higher complexity.