Search

Phosvitin shows chelating abilities, an affinity for ACTH (corticotropin), growth factors, antioxidant properties, and acidic nature. An attempt was made to use this protein in hydrogels as a transporter of other protein substances: somatotropin (STH) and (ACTH). The aim of the study was to evaluate the effect of phosvitin on the permeation of ACTH and STH from semi-solid forms of the drug applied to the skin. Four hydrogel substrates were prepared using natural polymers: sodium alginate, methylcellulose, and starch. Based on the evaluation of physicochemical parameters, the hydrogel with the most favorable properties was selected and loaded with the active substances STH and ACTH, followed by the addition of phosvitin. A study of the permeation of STH and ACTH through the artificial cellulose membrane and through porcine skin was carried out without and with the addition of phosvitin. The effect of protein substances on rheological and textural parameters was studied. The evaluation of physicochemical parameters showed a favorable effect of STH and Phosvitin on the stability of the hydrogel with 4% methylcellulose and no effect of ACTH. All prepared formulations showed a reaction close to the natural pH of human skin. In the porcine skin permeation study, the addition of Phosvitin to the hydrogel with STH caused a slight increase in the amount of STH permeated and an increase in the time for STH to permeate porcine skin by 30 min. Phosvitin caused an increase in the amount of ACTH permeated through porcine skin almost twofold. Phosvitin may prove to be a promising permeation promoter for model protein-peptide substances when applied to the skin surface. [ABSTRACT FROM AUTHOR]

Abstract The rheological parameters of oil testing fluids play a crucial role in safely conducting oil testing operations, protecting reservoirs, and maintaining wellbore integrity, which are greatly influenced by temperature and pressure. This article conducted rheological experiments on commonly used potassium salt polymer systems and organic salt systems for oil testing fluids in the Bohai Bay Oilfield under 4–200 °C and 30–150 MPa. The experiments revealed the variation of rheological parameters with temperature and pressure. Nine commonly used rheological models were evaluated for their applicability to the two types of oil testing fluids. It was found that the Ross model was suitable for the potassium salt polymer system, while the power-law model was suitable for organic salt oil testing fluids. A new rheological parameter prediction model suitable for wide range of temperature and pressure and different testing fluid systems was proposed based on the optimized results. The average error for the potassium salt polymer system for oil testing fluids was 0.101%, and the error for the organic salt system for oil testing fluids was 0.113%. Both were superior to known rheological models and can meet the requirements of oil testing operations within the wide temperature and pressure range in the Bohai Bay Oilfield.

Abstract A high-density water-based drilling fluid (WBDF) is crucial for maintaining wellbore stability, controlling formation pressures, and optimizing drilling performance in challenging subsurface conditions. In the present research, the effect of micronized calcium carbonate (calcite), extracted from the Aruma formation outcrop, is evaluated as one of the additives that could be added to the ilmenite-weighted WBDF to enhance and optimize its properties. Various concentrations of Calcite microparticles were introduced into identical fluid formulations to assess their impact. The concentrations ranged from 0, 10, 20, to 30 lb/bbl, providing a comprehensive examination of the effects of calcite microparticles across a spectrum of concentrations within the fluid. The results highlighted that adding Barite microparticles to the WBDF revealed a notable enhancement in rheological properties. Specifically, the yield point demonstrated an increase of 37%, 37%, and 11% for concentrations of 10, 20, and 30 lb/bbl of calcite, respectively. Equally significant, high-pressure-high-temperature (HPHT) filtration analysis indicated a considerable enhancement for the fluids containing calcite microparticles. A reduction of 14.5%, 24.6%, and 13% were observed in HPHT filtrate for concentrations of 10 lb/bbl, 20 lb/bbl, and 30 lb/bbl respectively. Simultaneously, there is a reduction in filter cake thickness by 20%, 40%, and 20%, respectively. No ilmenite settling was observed in the sample containing 20 lb/bbl of calcite, unlike the other concentrations. These diverse results strongly suggest that the optimal concentration for calcite microparticles is 20 lb/bbl. The combined utilization of the optimal concentration of calcite microparticles alongside the established additives proves to be an effective strategy for optimizing the ilmenite-weighted WBDF performance in terms of both thermal stability and rheological behavior.

The rheological parameters of oil testing fluids play a crucial role in safely conducting oil testing operations, protecting reservoirs, and maintaining wellbore integrity, which are greatly influenced by temperature and pressure. This article conducted rheological experiments on commonly used potassium salt polymer systems and organic salt systems for oil testing fluids in the Bohai Bay Oilfield under 4–200 °C and 30–150 MPa. The experiments revealed the variation of rheological parameters with temperature and pressure. Nine commonly used rheological models were evaluated for their applicability to the two types of oil testing fluids. It was found that the Ross model was suitable for the potassium salt polymer system, while the power-law model was suitable for organic salt oil testing fluids. A new rheological parameter prediction model suitable for wide range of temperature and pressure and different testing fluid systems was proposed based on the optimized results. The average error for the potassium salt polymer system for oil testing fluids was 0.101%, and the error for the organic salt system for oil testing fluids was 0.113%. Both were superior to known rheological models and can meet the requirements of oil testing operations within the wide temperature and pressure range in the Bohai Bay Oilfield. [ABSTRACT FROM AUTHOR]

In the context of the "dual carbon" goal, in order to solve the problem of high value utilization of modified magnesium and coal-based solid waste resources and efficient storage of carbon dioxide, CO2 gas was introduced into the modified magnesium-coal based solid waste backfill material under normal temperature and pressure conditions to prepare a new type of solid waste carbon fixation backfill material (CO2-MCSB). The preparation and flow performance study of CO2-MCSB provides a new technological approach combining solid waste resource utilization and CO2 storage, which can provide new theoretical references for solid waste backfill in mines. The effects of stirring rate, stirring time, and aeration rate on its fluidity and rheological properties were investigated through micro slump, rheological testing, and microstructure testing. The research results indicate that: (1) the slump range of freshly mixed CO2-MCSB slurry is 125 ~ 146 mm, and the expansion range is 9.5 ~ 39.5 cm, fully meeting the requirements of mine backfill fluidity. (2) The newly mixed CO2-MCSB slurry exhibits swelling fluid, and after ventilation, there is a significant thickening phenomenon, resulting in a significant decrease in flowability. (3) Microscopic analysis shows that the calcium carbonate generated by the carbonation reaction of the slurry after aeration fills the gaps, thereby increasing the probability of collision between internal particles and increasing the critical resistance for flow to begin. (4) There is a significant linear relationship between the flowability and rheological parameters of freshly mixed CO2-MCSB slurry, showing a negative correlation. (5) In the backfill application process, the stirring rate of 200 r/min, the aeration stirring time of 5 min, and the aeration rate of 5 L/min can be controlled to achieve good flow performance of CO2-MCSB. [ABSTRACT FROM AUTHOR]

This article is performed owing to the necessity to extend the range of domestic retarding reagents of thickening and hardening of tamponation solutions while cementing oil and gas wells. The piece of work is dedicated to the research of technological properties of tamponation materials with additions of reagent "dextrin" under conditions simulating reservoir conditions. The goal was set to substitute import of the reagent base of tamponation solutions, in particular, of the retarding reagent of hardening of tamponation solutions of nitrilotrimethylphosphonic acid (NTPHA) manufactured in Russia. The following requirements are placed to the new retarding reagent of hardening and thickening of tamponantion solutions: wide temperature interval of application, cost effectiveness and environmental compatibility of application. [ABSTRACT FROM AUTHOR]

A high-density water-based drilling fluid (WBDF) is crucial for maintaining wellbore stability, controlling formation pressures, and optimizing drilling performance in challenging subsurface conditions. In the present research, the effect of micronized calcium carbonate (calcite), extracted from the Aruma formation outcrop, is evaluated as one of the additives that could be added to the ilmenite-weighted WBDF to enhance and optimize its properties. Various concentrations of Calcite microparticles were introduced into identical fluid formulations to assess their impact. The concentrations ranged from 0, 10, 20, to 30 lb/bbl, providing a comprehensive examination of the effects of calcite microparticles across a spectrum of concentrations within the fluid. The results highlighted that adding Barite microparticles to the WBDF revealed a notable enhancement in rheological properties. Specifically, the yield point demonstrated an increase of 37%, 37%, and 11% for concentrations of 10, 20, and 30 lb/bbl of calcite, respectively. Equally significant, high-pressure-high-temperature (HPHT) filtration analysis indicated a considerable enhancement for the fluids containing calcite microparticles. A reduction of 14.5%, 24.6%, and 13% were observed in HPHT filtrate for concentrations of 10 lb/bbl, 20 lb/bbl, and 30 lb/bbl respectively. Simultaneously, there is a reduction in filter cake thickness by 20%, 40%, and 20%, respectively. No ilmenite settling was observed in the sample containing 20 lb/bbl of calcite, unlike the other concentrations. These diverse results strongly suggest that the optimal concentration for calcite microparticles is 20 lb/bbl. The combined utilization of the optimal concentration of calcite microparticles alongside the established additives proves to be an effective strategy for optimizing the ilmenite-weighted WBDF performance in terms of both thermal stability and rheological behavior. [ABSTRACT FROM AUTHOR]

The reduction in the rheological parameters and dissolution rate of precursors in geopolymer coatings during early hydration significantly contributes to sagging. This study aims to improve the sag resistance of these coatings by incorporating diatomite filler. Rheological testing was conducted to assess the impact of diatomite and its concentration on the yield stress, plastic viscosity, and thixotropy of the geopolymer coatings. The results indicated that diatomite's large specific surface area and high reactivity have a significant influence on the rheological parameters and early dissolution rate of precursors. With a diatomite concentration of 1.1%, the coating exhibited a yield stress of 2.749 Pa and a plastic viscosity of 0.921 Pa·s, maintaining stability, homogeneity, and no sagging at a thickness of 600 μm. Furthermore, the highly active SiO2 in diatomite participates in the secondary hydration reaction of the geopolymer materials led to the formation of substantial C-(A)-S-H gel. This gel enhances internal interconnectivity within the coating, thereby improving its rheological and mechanical properties. [ABSTRACT FROM AUTHOR]

Composite membranes based on a polymer mixture solution of quaternized polysulfone (PSFQ), cellulose acetate phthalate (CAP), and polyvinylidene fluoride (PVDF) for biomedical applications were successfully obtained through the electrospinning technique. To ensure the polysulfone membranes' functionality in targeted applications, the selection of electrospinning conditions was essential. Moreover, understanding the geometric characteristics and morphology of fibrous membranes is crucial in designing them to meet the performance standards necessary for future biomedical applications. Thus, the viscosity of the solutions used in the electrospinning process was determined, and the morphology of the electrospun membranes was examined using scanning electron microscopy (SEM). Investigations on the surfaces of electrospun membranes based on water vapor sorption data have demonstrated that their surface properties dictate their biological ability more than their specific surfaces. Furthermore, in order to understand the different macromolecular rearrangements of membrane structures caused by physical interactions between the polymeric chains as well as by the orientation of functional groups during the electrospinning process, Fourier transform infrared (FTIR) spectroscopy was used. The applicability of composite membranes in the biomedical field was established by bacterial adhesion testing on the surface of electrospun membranes using Escherichia coli and Staphylococcus aureus microorganisms. The biological experiments conducted establish a foundation for future applications of these membranes and validate their effectiveness in specific fields. [ABSTRACT FROM AUTHOR]

In the field of coal mine backfilling, the method of grading the coal gangue and the effect it has on the rheological properties of the cemented paste backfill (CPB) are still to be fully understood. In this study, the CPB is composed of coal gangue as the coarse aggregate, fly ash and cement as the fine aggregate. The properties of the coal gangue were characterised in terms of porosity and friction angle, and the comprehensive influence of different coal gangue grading, volume fraction and CPB mixture ratios on the rheological properties of the CPB was investigated. The experimental results indicate that both large and small coal gangue particle sizes can increase the porosity and friction angle. Compared with single grade and gap grade, coal gangue with continuous grade (G32) has a lower porosity of 42.1 %, a friction angle of 43.8 °, a yield stress of 7.6Nm and a viscosity of 6.5Nm, a higher slump of 221 mm, and a water film thickness of 1.68 μm. The yield stress has been identified as the primary factor influencing the slump of CPB. The yield stress and viscosity of the CPB are negatively correlated with the particle size, mortar ratio, and slump, and positively correlated with the volume fraction of coal gangue. In addition, the significant impact of various factors on the rheological parameters of the CPB is ranked as porosity> mortar ratio >volume fraction>friction angle. The relationship between yield stress, viscosity and water film thickness (WFT) is a power function, and the established WFT model can conveniently and quickly predict the rheological parameters of the CPB.

In rheological testing, different test regimes can result in large differences in the rheological curves, and the pre-shear procedure is one of the most important parts of the test. In order to investigate the effect of the pre-shear regime on the rheological properties of cement pastes, an Anton Paar 102 rotary rheometer was used for the test. Two different pre-shear regimes (RF and CP pre-shear), three different pre-shear duration times (50 s, 100 s, 150 s), and four different pre-shear rates (25 s-1, 50 s-1, 100 s-1) are carried out for the test. The results showed that with the increase of pre-shear duration or rate, the four rheological parameters (plastic viscosity, yield stress, rheological index, and thixotropy) of the pastes decrease in different degrees. RF pre-shear was more influenced by shear time, while CP pre-shear was influenced by shear time and rate. The pre-shear regimes led to different changes in the flocculation structure of the cement paste, which had a great influence on rheological parameters ultimately. Based on the improved Krieger-Dougherty model, the effective solid volume fraction of cement paste was calculated. Analysis shows that the phenomenon of "deflocculation" and "re-flocculation" occurs when the cement paste is subjected to shear action, thus, the pre-shear regimes destroy the structure of the pastes. With the increase of pre-shear duration or rate, the effective volume fraction decreased, which indicated that the initial flocculation structurewas broken. The greater the damage degree of pre-shear, the slower the establishment rate of the internal structure of the pastes in dynamic shear, resulting in lower rheological parameters. [ABSTRACT FROM AUTHOR]

The aging of asphalt binders has a great impact on the behavior of pavement. The specifications for performance grade include tests on short-term (RTFOT) and long-term (PAV) aged residues. However, aging is greater at the top of wearing course than deeper zones, longterm tests do not correlate accurately with field aging and in the latter, the incidence of local temperature is not considered accurately. The objective is to relate the aging of Ecuadorian asphalt at the laboratory level, applying different conditioning times in the PAV, with the field aging from asphalts recovered from the top of pavements surface in selected roads of the Andean and Coastal regions, with different construction times and cumulated degree-days (CDD), using certain rheological parameters. As a result, in the Ecuadorian asphalt, the RTFOT residue is equivalent to field aging of 1.1 years in the Coastal region and 1.7 years in the Andean region. On the other hand, the usual PAV of 20 hours corresponds to field aging of 5.8 years for the Coastal region and 9.3 years for the Andean region. The progressive evolution of damage to our roads, without considering traffic, corresponds to conditioning times in the PAV between 13.0 and 26.6 hours. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies on the effect of multi-walled carbon nanotubes (MWCNTs) additives on the viscosity and rheological characteristics of drilling emulsions based on mineral oil. The formulations of typical drilling fluids containing 65% hydrocarbon phase were modified with nanotubes. The mass concentration of nanotubes in emulsion varied from 0.1 to 0.5%. The formulation and method of preparing stable drilling emulsions with MWCNT additives have been proposed. The rheology of drilling emulsions modified with MWCNTs was studied. The dependency of rheological characteristics on the nanotubes concentration was obtained. In general, MWCNT additives can significantly alter the rheological characteristics of drilling hydrocarbon emulsions at lower concentrations compared to the additives in the form of spherical nanoparticles. This is very important for their practical use in industry. The optimal concentration of MWCNTs for controlling the rheological properties of drilling emulsions is about 0.25 wt. %. [ABSTRACT FROM AUTHOR]

The Anton Paar MCR 52 intelligent high-speed rheometer was utilized in this paper to conduct rheological tests on the Jiangjiagou debris flow slurry via linear loading. The relationship curves between shear rate and shear stress at different solid volume concentrations were obtained, and predictive formulas for yield stress and viscosity coefficient variations with the shear rate are proposed. Furthermore, the evolution mechanisms of yield stress and viscosity coefficient with changes in solid volume concentration of the debris flow were thoroughly analyzed. The results indicated that the rheological curves of the Jiangjiagou debris flow conformed to the Bingham fluid model. An increase in solid volume concentration continuously promoted the upward trend of the rheological curves, with significant increments observed only at high volume concentrations. A predictive model for debris flow rheological parameters was established based on the linear relationship between the rheological parameters and the solid volume concentration. The rise in solid volume concentration inhibited turbulence in the debris flow, while clay minerals enhanced the debris flow slurry's ability to capture pore water. Significant shear-thinning effects were observed within the debris flow, which were particularly more pronounced at lower shear rates. The study outcomes hold crucial engineering significance for a better understanding of debris flow rheological properties, the calculation of debris flow dynamic parameters, and disaster prevention and control. [ABSTRACT FROM AUTHOR]

The article discusses the problem of determining the rheological parameters of polymers from stress relaxation curves using the CatBoost machine learning algorithm. The model is trained on theoretical curves constructed using the nonlinear Maxwell–Gurevich equation. Comparisons are made with other methods, including the classical algorithm, nonlinear optimization methods, and artificial neural networks. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical properties of backfill, steel slag and straw fiber were used as materials to prepare backfill. The law of sand-cement ratio, mass concentration, steel slag content and straw fiber on strength and rheological parameters of backfill was analyzed by orthogonal test method, and the influence mechanism of steel slag content and straw fiber on physical properties of backfill was revealed. The results show that mass concentration exerts the most substantial impact on rheological parameters, emerging as a significant determinant. Moreover, the yield stress diminishes with escalating tailings-cement ratio, while it escalates with higher mass concentration, steel slag content and straw fiber content. Augmenting the tailings-cement ratio and steel slag content serves to impede the amplification effect of mass concentration on yield stress. Notably, the tailings-cement ratio emerges as the most influential factor affecting the uniaxial compressive strength (UCS) of the backfill, albeit the UCS diminishes with rising tailings-cement ratio. Elevating the mass concentration and steel slag content can counteract the debilitation caused by an increase in the tailings-cement ratio on the UCS of the backfill. Furthermore, heightened mass concentration can bolster the reinforcing impact of steel slag content on early UCS. The increase of tailings-cement ratio increases the size and range of the void inside the backfill, subsequently leading to the degradation of its macroscopic compressive strength. The adhesion between straw fiber and mortar matrix constitutes a pivotal factor in improving the integration of backfill, whereas steel slag contributes to improving the mechanical properties by enhancing the distribution of void structures within the backfill. This research not only offer data support and scientific guidance for the design of backfill ratio parameters but also facilitate the broader application of straw fiber and steel slag in mine backfilling operations.

The article proposes to study the influence of new protein-containing raw materials, namely cricket flour (CF) Acheta domesticus on the quality of whipped flour semi-finished product (WFP) research methods. The study used generally accepted methods for determining the rheological properties of the dough: the dependence of viscosity on shear stress, temperature, and rate of deformation of the dough, as well as the elasticity of finished products and physicochemical properties of the finished semi-finished product. The mass fraction of moisture was determined by drying to constant weight. The mass fraction of ash not dissolved in 10% hydrochloric acid in absolute dry matter was determined using the dry method in a muffle furnace. The mass fraction of protein was determined by the Kjeldahl method. Alkalinity was determined by the titrometric method. The mass fraction of total sugar was determined by the iodometric method. During the manufacture of WFP, cricket flour was added to 5.0-15.0%. The results of rheological parameters showed that adding CF to the dough in an amount of 15.0% significantly affected the viscosity and plasticity of the dough, which led to a decrease in volume and porosity in the finished semi-finished product. According to physicochemical parameters, it was found that with increased BC concentration, the mass fraction of protein increases (from 4.4% in conventional WFP to 62.06% with the addition of CF in the amount of 10.0%). At the same time, the mass fraction of total sugar decreases. The mass fraction of moisture in the finished semi-finished product also changes. The resiliency and elasticity of the finished products were determined by the laboratory method using the "Labor" penetrometer. According to the results of studies of resiliency and elasticity of the finished product, it was determined that the semi-finished product with the addition of 15.0% cricket flour had the lowest indicators compared to the products with the addition of 5.0% and 10.0% cricket.

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fatigue failure in asphalt pavements, caused by continuous loading, primarily occurs at the interface between the asphalt binder and the aggregate (adhesive failure) or within the asphalt binder itself (cohesive failure). This study conducted variable stress fatigue tests on asphalt binders to investigate the fatigue damage evolution mechanism that aligns most closely with actual road conditions. By altering test conditions such as stress amplitude and loading frequency, the study summarized the patterns of change in the fatigue performance parameters of binder samples and analyzed their fatigue life. The research methods employed are of significant value for refining the existing asphalt fatigue evaluation systems. Indicators such as dissipated energy ratio, cumulative dissipated energy ratio, rate of change in dissipated energy, and the G-R constant n × Gn* were used as criteria for fatigue failure. The fatigue life of samples under different stress levels was calculated, and the applicability of each dissipated energy fatigue indicator was evaluated. The evaluation indicators, like dissipated energy ratio and cumulative dissipated energy ratio, failed under large stress outside the non-linear viscoelastic range, whereas the rate of change in dissipated energy and the G-R constant n × Gn* accurately determined the fatigue life of samples in fatigue tests at all stress levels, covering a broader range of applicable stresses. In variable stress fatigue tests, the rate of change in dissipated energy and the G-R constant were used as indicators for determining fatigue failure. Under a small-to-large loading mode, the second stage of the sample's fatigue life was too short, causing the G-R constant curve to not reach its peak, and hence it could not accurately determine the sample's fatigue life. Under a large-to-small loading mode, there are sufficient loading cycles before fatigue failure occurs, allowing the G-R constant curve to reach its peak, demonstrating that the G-R constant remains applicable in this loading mode. Under both small-to-large and large-to-small loading modes, the fatigue failure point of the samples could be determined based on the rate of change in dissipated energy curve. It is recommended to use the rate of change in dissipated energy as the failure criterion for samples in variable stress fatigue tests on asphalt binders. [ABSTRACT FROM AUTHOR]

To know the mixing flowability in theory and quantitatively evaluate the mixing workability of the asphalt mixture, a variable speed mixing (VSM) test device was developed in our laboratory. Different asphalt mixtures are tested by recording the mixing power under different mixing speeds (20∼50 r·min-1) and different mixing temperatures (130∼180 °C) to analyze the mixing flowability. Afterwards, the mixing workability index was defined from rheological parameters by establishing the mixing flow model. The experimental results indicate that the mixing flowability of asphalt mixtures obeys the linear Bingham's visco-plastic model, which conducts two mixing rheological parameters including the mixing plastic limit and the mixing viscosity by the intercept and slope of the flow straight respectively. When the mixing temperature increases, the mixing viscosity decreases and the workability index increases, but the mixing plastic limit is not affected. With the increase of the nominal maximum particle size of asphalt mixtures, the mixing plastic limit increases and the workability index decreases, but the mixing viscosity is not affected. The asphalt becomes more viscous as the asphalt content increase, which leads to worse workability. The composition of aggregate determines the mixing plastic limit, and the viscosity of asphalt mortar determines the mixing viscosity. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mining Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the various rheological behaviors such as shear rate, viscosity, and shear stress of semi-solid slurry of ADC12 Al alloy are investigated. As-received ADC12 Al alloy is melted and kept above the liquidus temperature (560 °C and 565 °C) to observe the viscosity, shear rate, and shear stress behavior of semi-solid slurry. There is a drastic decrease in the viscosity with an increase in shear rate and temperature. In this, it is observed that the low viscous semi-solid slurry is better for easily filling the mold cavity. The finer α-Al particles are observed in microstructural features of the oil-quenched semi-solid slurry of ADC12 alloy. A 3D model of the valve housing is used to simulate the mold-filling behavior of the semi-solid slurry of ADC12 Al alloy. The flow behavior of ADC12 Al alloy reveals that the low-speed range of plunger movement is the optimum condition to fill the mold cavity. The uniform temperature distribution in the mold also reduces the casting defects such as voids and porosity. [ABSTRACT FROM AUTHOR]

Dairy cream, a common ingredient in various dishes and food products, is susceptible to rapid microbial growth due to its high water activity (≈0.97) and pH (≈6.7). Thus, it requires proper processing conditions to ensure food safety and extend shelf life. High-pressure processing (HPP) has emerged as a nonthermal food pasteurization method, offering an alternative to conventional heat-based techniques to obtain tastier, fresh-like, and safe dairy products without undesirable heat-induced alterations. This study assessed the impact of HPP (450 and 600 MPa for 5 and 15 min at 7 °C) and thermal pasteurization (75 °C for 15 s) on the microbiological and physicochemical attributes of dairy cream immediately after processing and throughout refrigerated storage (4 °C). HPP-treated samples remained microbiologically acceptable even on the 51st day of storage, unlike thermally pasteurized samples. Moreover, HPP decreased inoculated Escherichia coli and Listeria innocua counts by more than 6 log units to undetectable levels (1.00 log CFU/mL). pH, color (maximum variation of ΔE* up to 8.43), and fatty acid profiles remained relatively stable under varying processing conditions and during storage. However, viscosity exhibited higher values for HPP-treated samples (0.028 ± 0.003 Pa·s) compared to thermally processed ones (0.016 ± 0.002 Pa·s) by the 28th day of storage. Furthermore, volatile compounds (VOCs) of all treated samples presented a tendency to increase throughout storage, particularly acids and aliphatic hydrocarbons. These findings show HPP's potential to significantly extend the shelf life of highly perishable dairy cream by at least 15 days compared to thermal pasteurization. [ABSTRACT FROM AUTHOR]

Three types ol water reducers, namely polycarboxylate superplasticizer, melamine super plasticizer, and naphthalene superplasticizer, were used in this study to test the fluidity, rheology, and strength ol backlill at different dosages ol water reducer. The effects ol water reducer type and dosage on the Iluidity, yield stress, plastic viscosity, apparent viscosity, thixotropy, and strength ol the backlill were studied. Research result showed that adding a water reducer can significantly improve slurry's Iluidity, and reduce yield stress and apparent viscosity. The effect ol water reducer on the plastic viscosity ol slurry was relatively small. In addition, the thixotropy ol slurry increased firstly and then decrease with the increase of water reducer content Compared with melamine superplasticizer and naphthalene superplasticizer, polycarboxylate superplasticizer has a more noticeable imp rovemen t ellect on slurry Ilowability. At a certain concentration, adding a water reducer will reduce the early strength ol the backlill, but it has a small impact on the strength ol the backlill in the middle and later stages, even slightly increased. [ABSTRACT FROM AUTHOR]

The reduction in the rheological parameters and dissolution rate of precursors in geopolymer coatings during early hydration significantly contributes to sagging. This study aims to improve the sag resistance of these coatings by incorporating diatomite filler. Rheological testing was conducted to assess the impact of diatomite and its concentration on the yield stress, plastic viscosity, and thixotropy of the geopolymer coatings. The results indicated that diatomite’s large specific surface area and high reactivity have a significant influence on the rheological parameters and early dissolution rate of precursors. With a diatomite concentration of 1.1%, the coating exhibited a yield stress of 2.749 Pa and a plastic viscosity of 0.921 Pa·s, maintaining stability, homogeneity, and no sagging at a thickness of 600 μm. Furthermore, the highly active SiO2 in diatomite participates in the secondary hydration reaction of the geopolymer materials led to the formation of substantial C-(A)-S-H gel. This gel enhances internal interconnectivity within the coating, thereby improving its rheological and mechanical properties.

Composite membranes based on a polymer mixture solution of quaternized polysulfone (PSFQ), cellulose acetate phthalate (CAP), and polyvinylidene fluoride (PVDF) for biomedical applications were successfully obtained through the electrospinning technique. To ensure the polysulfone membranes’ functionality in targeted applications, the selection of electrospinning conditions was essential. Moreover, understanding the geometric characteristics and morphology of fibrous membranes is crucial in designing them to meet the performance standards necessary for future biomedical applications. Thus, the viscosity of the solutions used in the electrospinning process was determined, and the morphology of the electrospun membranes was examined using scanning electron microscopy (SEM). Investigations on the surfaces of electrospun membranes based on water vapor sorption data have demonstrated that their surface properties dictate their biological ability more than their specific surfaces. Furthermore, in order to understand the different macromolecular rearrangements of membrane structures caused by physical interactions between the polymeric chains as well as by the orientation of functional groups during the electrospinning process, Fourier transform infrared (FTIR) spectroscopy was used. The applicability of composite membranes in the biomedical field was established by bacterial adhesion testing on the surface of electrospun membranes using Escherichia coli and Staphylococcus aureus microorganisms. The biological experiments conducted establish a foundation for future applications of these membranes and validate their effectiveness in specific fields.

In order to determine the influence of blast furnace slag on the initial shear force τ0 and viscosity coefficient η of mortar, an experimental study on the influence of blast furnace slag on rheological parameters of mortar was put forward. A new type of testing device, L-shaped tube, was used to measure the variation of slurry flow rate with slag content in fresh mortar. Combined with the theory of concrete rheology and fluid mechanics, numerical analysis was carried out, and the calculation method of rheological parameters τ0 and η of mortar in L-shaped pipe was obtained. Through calculation and comparative analysis, the influence of slag content on rheological parameters of mortar was obtained. The results show that a small amount of slag can improve the rheological properties of mortar. When the diameter and shape of glass are constant, the regression curves of rheological parameters τ0 and η of mortar increase linearly with the content of mineral powder. When the content of blast furnace slag is 10%, the rheological property of mortar is the best. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-concentration tailings pastes are commonly encountered in the surface deposition and underground cemented paste backfill. It is necessary to forecast the pressure loss along the pipe and the flow behavior in the mined-out area when tailings pastes are transported in a pipeline or stored up in goaf. Traditionally, thixotropy has often been overlooked while designing tailings paste transport and disposal systems due to the complexity of thixotropy characterization. However, thixotropy plays an essential role in the rheology of tailings pastes. To achieve the accurate representation of thixotropy, a suitable constitutive model has to be selected in advance. Unfortunately, there is no current available thixotropic model for tailings pastes up to date. Moreover, tailings pastes exhibit complex thixotropy that is significantly affected by the particle size of tailings, though the relevant studies are not abundant. It is important to analyze quantitively the relationship between particle size and thixotropic parameters based on an appropriate constitutive model. In this work, the constitutive thixotropic model for tailings pastes proposed by Zhang et al. was adopted. To reveal the influence of particle size on the thixotropy of tailings pastes, samples of various mean particle sizes prepared from the same tailings were applied to constant shear rate experiments. Results show that the target tailings pastes display significant thixotropy, leading to shear thinning under steady shear rates. In the steady state, the static yield stress, dynamic yield stress, and Bingham viscosity appear to correlate linearly to the reciprocal of the square of the mean particle size. As for the transient state, the corresponding fit parameters show a strong linear dependence on the mean particle size. The proposed equilibrium and thixotropic models are valid. The forecasting models for equilibrium and transient shear stress are established based on data fit, which is attributed to the quantitative characterization of steady-state and transient rheology for thixotropic tailings pastes under the effect of particle size.

Incinerated waste fly ash is a toxic solid, which can cause serious harm to the environment. CO2-cured incinerated waste fly ash may be useful in decreasing the toxicity of waste fly ash and improving the corresponding mechanical properties of cement-based material with incinerated waste fly ash. Meanwhile, this technology can play a certain role in reducing the content of CO2 in the atmosphere. In this study, the influence of CO2-cured incinerated waste fly ash on the rheological parameters (the slump flow and plastic viscosity) and the setting time of fresh reactive powder cement concrete (RPC) is investigated. The flexural and compressive strengths of hardened RPC standard cured for 1 day, 3 days, and 28 days are measured. The leached amounts of Cr and Zn immersed in water for 6 months are measured. The scanning electron microscope photos, thermogravimetric analysis curves, and mercury intrusion curves are obtained. Our results show that the slump flow, the setting time, and the flexural and compressive strengths increased, and the plastic viscosity decreased by adding the waste fly ash with the maximum varying rates of 12.1%, 41.7%, 41.3%, and 61.2%, respectively. CO2 curing on the waste fly ash can increase the setting time and the flexural and compressive strengths with the maximum varying rates of 19.2%, 13.1%, and 14.2%. The effect of CO2-cured waste fly ash on the mechanical strengths of RPC is quite limited. [ABSTRACT FROM AUTHOR]

This study evaluated the rheological behavior of the pig waste biotransformation process to produce lactic acid (LA) and biomass with Lactobacillusacidophilus in a stirred reactor. In addition, cell growth, carbohydrate consumption, and LA production were measured at three different agitation speeds, 100, 150, and 200 rpm at 37 °C, with a reaction time of 52 h. During the development of the process, the kinetic and rheological parameters were obtained using the logistic, Gompertz, generalized Gompertz, Ostwald de Waele, and Herschel–Bulkley mathematical models, respectively. The substrate used was pig manure, to which molasses was added at 12% v/v to increase the concentration of carbohydrates. The results suggest that mass exchange is favorable at low agitation speeds. Nevertheless, the presence of molasses rich in carbohydrates as a carbon source modifies the characteristics of the fluid, dilatant (n > 1) at the beginning of the process to end up as pseudoplastic (n < 1) due to the addition of exopolysaccharides and the modification of the physical structure of the substrate. This effect was confirmed by the Herschel–Bulkley model, which presented a better fit to the data obtained, in addition to finding a direct relationship between viscosity and pH that can be used as variables for the control of bioconversion processes of pig manure into biomass rich in Lactobacillus acidophilus. [ABSTRACT FROM AUTHOR]

The Anton Paar MCR 52 intelligent high-speed rheometer was utilized in this paper to conduct rheological tests on the Jiangjiagou debris flow slurry via linear loading. The relationship curves between shear rate and shear stress at different solid volume concentrations were obtained, and predictive formulas for yield stress and viscosity coefficient variations with the shear rate are proposed. Furthermore, the evolution mechanisms of yield stress and viscosity coefficient with changes in solid volume concentration of the debris flow were thoroughly analyzed. The results indicated that the rheological curves of the Jiangjiagou debris flow conformed to the Bingham fluid model. An increase in solid volume concentration continuously promoted the upward trend of the rheological curves, with significant increments observed only at high volume concentrations. A predictive model for debris flow rheological parameters was established based on the linear relationship between the rheological parameters and the solid volume concentration. The rise in solid volume concentration inhibited turbulence in the debris flow, while clay minerals enhanced the debris flow slurry’s ability to capture pore water. Significant shear-thinning effects were observed within the debris flow, which were particularly more pronounced at lower shear rates. The study outcomes hold crucial engineering significance for a better understanding of debris flow rheological properties, the calculation of debris flow dynamic parameters, and disaster prevention and control.

Fatigue failure in asphalt pavements, caused by continuous loading, primarily occurs at the interface between the asphalt binder and the aggregate (adhesive failure) or within the asphalt binder itself (cohesive failure). This study conducted variable stress fatigue tests on asphalt binders to investigate the fatigue damage evolution mechanism that aligns most closely with actual road conditions. By altering test conditions such as stress amplitude and loading frequency, the study summarized the patterns of change in the fatigue performance parameters of binder samples and analyzed their fatigue life. The research methods employed are of significant value for refining the existing asphalt fatigue evaluation systems. Indicators such as dissipated energy ratio, cumulative dissipated energy ratio, rate of change in dissipated energy, and the G-R constant n × Gn* were used as criteria for fatigue failure. The fatigue life of samples under different stress levels was calculated, and the applicability of each dissipated energy fatigue indicator was evaluated. The evaluation indicators, like dissipated energy ratio and cumulative dissipated energy ratio, failed under large stress outside the non-linear viscoelastic range, whereas the rate of change in dissipated energy and the G-R constant n × Gn* accurately determined the fatigue life of samples in fatigue tests at all stress levels, covering a broader range of applicable stresses. In variable stress fatigue tests, the rate of change in dissipated energy and the G-R constant were used as indicators for determining fatigue failure. Under a small-to-large loading mode, the second stage of the sample’s fatigue life was too short, causing the G-R constant curve to not reach its peak, and hence it could not accurately determine the sample’s fatigue life. Under a large-to-small loading mode, there are sufficient loading cycles before fatigue failure occurs, allowing the G-R constant curve to reach its peak, demonstrating that the G-R constant remains applicable in this loading mode. Under both small-to-large and large-to-small loading modes, the fatigue failure point of the samples could be determined based on the rate of change in dissipated energy curve. It is recommended to use the rate of change in dissipated energy as the failure criterion for samples in variable stress fatigue tests on asphalt binders.

Non-Newtonian fluids are commonly used in a wide range of industries; one example are in biogas power plants. Proper measurements and modeling of such fluids can be crucial from the design and operations point of view. Results presented in this study covered seven samples from three plants (a sewage sludge treatment plant, utilization biogas station and a biogas plant in a sugar factory), including mechanically thickened excessive activated sludge (MTEAS), sugar beet pulp (SBP), liquid fruit and vegetable waste (FVW), beet roots (BR) and corn waste (CW); their mixtures were prepared as in a real plant. The total solid content remained below 6.8% for all samples. The apparent viscosity (15 RPM) did not exceed 10 Pas in any sample. A correlation analysis for solvent type influence on the viscosity was carried out. The obtained results were analyzed, and the Herschel–Bulkley rheological model was selected for the fluid description. Then, the Moullinex method was applied to determine the H–B model parameters. The obtained results may contribute to the proper design and operation of various biogas power plants, in which viscosity seems to be one of the crucial flow parameters that influences the device types used, as well as energy consumption. [ABSTRACT FROM AUTHOR]

The distribution of the flow field, the input energy of the twin‐screw, and the dissipated energy on the fluid during the twin‐screw extrusion process were calculated by the POLYFLOW software to establish the relationship between the rheological parameters of starch fluid and tensile properties of the final extrudate. The results demonstrated that the pressure difference, the input energy of the twin‐screw, and the dissipated energy on the fluid were directly proportional to the zero‐shear viscosity (η0), reduced with the raise of the relaxation time constant (λ) and raised with the raise of the power‐law index (n). When the moisture content of starch fluid raised, the η0 value reduced, whereas the λ value and n value increased. The pressure difference, the input energy of the twin‐screw, and the dissipated energy on the fluid decreased, reducing the maximum tensile force of the final extrudate. Through numerical simulation and experimental verification, it was found that the changes of η0 value, λ value, and n value restricted each other on the tensile properties of final extrudate. Based on the numerical simulation, the tensile properties of the final extrudate could be predicted through rheological parameters of starch fluid. Practical Applications: A method was established to predict the final extrudate properties based on rheological parameters and numerical simulation in this study. Based on the numerical simulation, the tensile properties of the final extrudate could be predicted through rheological parameters of starch fluid. This research will provide insight into the mechanism of twin‐screw extrusion of starch‐based materials. [ABSTRACT FROM AUTHOR]

BACKGROUND: Prevention of Type 2 diabetes mellitus (T2DM) requires a modifying effect on the pathological processes inducing the β-cell dysfunction. OBJECTIVES: the comprehensive study of the violation of rheological parameters in patients with different stages of diabetes and identification of possible links between these alterations with the intensity of the oxidative stress in the patient's body. METHODS: 60 patients with IR, prediabetes, T2DM and healthy volunteers were included. Full range of the rheological parameters of the patients' blood - the indicators of erythrocytes aggregation index (EAI), the relative deformability of the erythrocytes membranes (ERDI), blood plasma viscosity (BPV), and oxidative stress intensity (OSI) were examined. RESULTS: In patients with insulin resistance (IR), prediabetes, and T2DM the ERDI was statistically significantly lower and BPV - higher compared to control; a significant increase in EAI was detected in the patient group with prediabetes and T2DM compared to the control. CONCLUSION: The level of rheological disorders in patients increases with the increase of the level of carbohydrate metabolism disorders and intensity of oxidative stress and reaches a maximum during manifested diabetes. Diagnosis of hemorheological disorders and OSI in T2DM can serve as an early marker of target organ damage possibility. [ABSTRACT FROM AUTHOR]

The present work studies the efficiency of new innovative quaternized polysulfone (PSFQ)/ionic liquid (IL) membranes in the treatment process of water containing cadmium ions (Cd(II)). The design and development of the polysulfone membranes with morphology tailored by the use of ILs (Cyphos 101 IL and Aliquat 336) was based on the rheological study of the casting solutions that dictated the optimal compositions of ILs and facilitated the preparation of the membranes for performance tests. Thus, according to the variation of the rheological functions obtained (G′, G″), it was demonstrated that Aliquat 336 has better compatibility with PSFQ, facilitating the workability of the solution and improving the final properties of the membranes relative to Cyphos 101 IL. However, the casting solutions consisting of 5 wt.% Ph-IL and 15 wt.% Am-IL content produce membranes with superior physico-chemical properties. Also, the surface chemistry and morphology analysis of the membranes obtained were investigated in order to understand the relationship between the PSFQ and ILs, as well as their surface properties, as indicators for their future applications. Additionally, the results obtained from the kinetic studies regarding Cd(II) removal from aqueous solutions and the amount of Cd(II) accumulated onto the membranes showed that the ILs enhance the filtration efficiency of the membranes studied and underlined the positive effect of IL in the structure of the quaternized polysulfone membranes. A content of 15 wt.% Aliquat 336 in PSFQ membranes shows the best properties for Cd(II) removal from aqueous solutions; the maximum amount of Cd(II) accumulated on the membrane studied was 3300 mg/m2. This behaviour was maintained for two cycles of washing/filtration, and then the efficiency decreased by 20%. The results obtained showed that the membranes functionalized with ionic liquid could be used efficiently in the treatment of water containing trace concentration of cadmium. [ABSTRACT FROM AUTHOR]

Self‐compacting concrete (SCC) is a fluid concrete designed to flow freely through reinforcements in order to completely fill the formwork. The appearance of this type of concrete increases the need to precisely characterize its compressive strength as a function of their behavior during flow. This article summarizes the use of artificial neural networks for the modelization of compressive strength, at 28 days, of SCC based on rheological parameters found during empirical tests (slump flow diameter, H2/H1 ratio of L‐Box, and V‐Funnel flow time) and the values of plastic viscosity and the yield stress. The objective of this numerical and experimental study is to find an optimal model to modelize the compressive strength. Thus, the results obtained after training of several models are showed that the architecture of the optimum with two hidden layers model is 5‐50‐50‐1 with a Pearson's correlation R = 97.58%. [ABSTRACT FROM AUTHOR]

Over time, bitumen experiences deterioration due to factors like the exposure to oxygen, solar irradiation, and temperature fluctuations. While laboratory techniques like rolling thin film oven (RTFO) and pressure ageing vessel (PAV) were developed to simulate field ageing, they do not accurately replicate environmental factors normally occurring in the field, particularly solar irradiation. Limited research has focused on understanding the ageing processes of crumb rubber modified bitumen (CRMB). This study investigated how different ageing conditions affect the chemo-rheological properties of CRMB and CRMB with geopolymer-based fly ash (GFA), Portland cement paste (PCP), and carbon black (CB). GFA and PCP were added to reduce noxious fumes and VOC emissions from CRMB whereas CB is commonly employed as an antioxidant agent. RTFO and PAV were used to simulate short- and long-term ageing, while a SUNTEST XLS+ weatherometer was used for thermal and UV ageing simulations. A dynamic shear rheometer and attenuated total reflectance Fourier transform infrared spectroscopy were employed for rheological and chemical analysis. Results indicated that extended exposure to thermal conditioning and UV irradiation had the most impact on the chemo-rheological properties of the binders. The incorporation of CR into bitumen enhanced ageing resistance and mitigated the potential for stiffening and embrittlement. The addition of GFA, PCP, and CB to CRMB had a negligible impact on the chemo-rheological properties when subjected to RTFO, PAV, and thermal conditioning. However, following UV ageing, these additives led to a slight increase in carbonyl bonds and greater stiffness compared to pure CRMB • Thermal and UV ageing revealed the highest impact on the rheological parameters of CRMB. • With ageing, stiffness and elasticity in CRMB and CRMB+ERAs noticeably increase. • Incorporating CR into bitumen demonstrated enhanced ageing resistance. • GFA and PCP had minimal impact on CRMB's rheology after RTFO, PAV, and thermal conditioning. • UV ageing acts as a catalyst, intensifying the damage inflicted during thermal ageing. [ABSTRACT FROM AUTHOR]

Dairy cream, a common ingredient in various dishes and food products, is susceptible to rapid microbial growth due to its high water activity (≈0.97) and pH (≈6.7). Thus, it requires proper processing conditions to ensure food safety and extend shelf life. High-pressure processing (HPP) has emerged as a nonthermal food pasteurization method, offering an alternative to conventional heat-based techniques to obtain tastier, fresh-like, and safe dairy products without undesirable heat-induced alterations. This study assessed the impact of HPP (450 and 600 MPa for 5 and 15 min at 7 °C) and thermal pasteurization (75 °C for 15 s) on the microbiological and physicochemical attributes of dairy cream immediately after processing and throughout refrigerated storage (4 °C). HPP-treated samples remained microbiologically acceptable even on the 51st day of storage, unlike thermally pasteurized samples. Moreover, HPP decreased inoculated Escherichia coli and Listeria innocua counts by more than 6 log units to undetectable levels (1.00 log CFU/mL). pH, color (maximum variation of ΔE* up to 8.43), and fatty acid profiles remained relatively stable under varying processing conditions and during storage. However, viscosity exhibited higher values for HPP-treated samples (0.028 ± 0.003 Pa·s) compared to thermally processed ones (0.016 ± 0.002 Pa·s) by the 28th day of storage. Furthermore, volatile compounds (VOCs) of all treated samples presented a tendency to increase throughout storage, particularly acids and aliphatic hydrocarbons. These findings show HPP’s potential to significantly extend the shelf life of highly perishable dairy cream by at least 15 days compared to thermal pasteurization.

In the current research, Enterococcus mundtii SRBG1 newly isolated from Bat guano was encapsulated using spray drying technique to create a probiotic powder using six combinations of inulin, maltodextrin and sodium alginate. The encapsulation yield, moisture content, physical characteristics, and shape were investigated. Microcapsules yields ranged from 67 to 85 percent, which is consistent with typical B-290 spray-drier yields. The moisture content showed to increase (4 ± 0.15%) with the addition of sodium alginate to inulin and maltodextrin. In the gastrointestinal conditions (simulated gastric juice and bile salts), it was shown that the viability of probiotic cells in capsules was higher than that of free cells. This demonstrated the effectiveness of combining inulin and maltodextrin to encapsulate substances in surviving in gastro-intestinal conditions. Additionally, we evaluated the non-encapsulated and encapsulated SRBG1 by assessing their impact on the rheological parameters of fermented milk. The results showed that in the absence of sodium alginate the viscosity of milk was lower than with the other protectors, which was confirmed by the quick acidification of the fermented milk by microcapsules containing sodium alginate.

Simple Summary: The consumption of fermented milk products can have health benefits, particularly for those that suffer from lactose intolerance. Condition that is usually caused by insufficient production in the intestinal epithelium of lactase, the enzyme that facilitates the digestion of milk sugar (lactose). The lactose originally present in fermented beverages undergoes fermentation to lactic acid, so its concentration is lower than in processed milk. The aim of this study was to determine the effects of the storage time of fermented beverages made from sheep's milk on the lactose content of kefir and yogurts inoculated with various starter cultures. The drinks were made from sheep's milk with natural fat content. A sensory evaluation of the products was carried out to determine the most favorable date of consumption in terms of lactose concentration and organoleptic values. Effects of both inoculation type and beverage storage time were shown for all the parameters. Analysis showed that the optimal storage time for natural yogurt was 21 days. If kefir is to have its optimal taste, storage for more than fourteen days is not advised. The aim of the research was to evaluate lactose content and rheological, physical, chemical, and organoleptic parameters during the storage of fermented beverages made from sheep's milk. The research was carried out on natural, probiotic, and Greek-type yogurts, as well as kefir. The products were made using the thermostat method from the milk of 42 East Frisian sheep in the middle lactation period, in duplicate. Lactose contents, active and titratable acidity, color by the L*a*b*C*h* system, and rheological parameters (hardness, consistency, consistency, and viscosity) were tested, and organoleptic assessments were carried out on the first, seventh, fourteenth, and twenty-first days of storing the drinks at 4 °C. Of all drinks, the highest reduction in lactose after 21 days of storage was found to occur in kefir (52% reduction) and, among the yogurts, in the Greek yogurt (41% reduction). The product with the lowest lactose content, regardless of the storage period, was kefir. This indicates that kefir is more suitable than yogurt for people with partial lactose intolerance. Effects of both inoculation type and beverage storage time were shown to exist for all parameters. It was also found that kefirs suffered deterioration in most rheological parameters and, in general organoleptic evaluation in the final period of storage. Based on our analysis, the optimal storage time for natural yogurts and sheep's milk kefirs at 4 °C was 21 and 14 days, respectively. [ABSTRACT FROM AUTHOR]

Film-forming solutions based on four types of biopolymers were prepared and their rheological properties were determined. High methylated apple pectin and sodium alginate were used at the concentrations 1%, 1.5%, and 2%, whereas soy protein isolate and pork gelatin were obtained at 4%, 8%, and 12%. The parameters determining the production of the appropriate type of packaging film or edible coating are the setting time on the substrate, regardless of its type, and the gelation temperature, which were analyzed in the study by determination of flow curves and rheological parameters of prepared dispersions. The Newtonian model was used to describe the flow curves of the gelatin and sodium alginate solutions, while the Ostwald–de Waele model was used to describe the flow curves of the soy protein isolate and high methylated apple pectin solutions. The apparent viscosity of all solutions increased with increasing biopolymer concentrations, from 0.0042 to 0.0061 Pa·s and from 0.0187 to 0.0884 Pa·s for high-methylated apple pectin and sodium alginate, respectively; whereas, for a protein-based solution the viscosity increase was from 0.024 to 0.100 Pa·s and from 0.0018 to 0.0056 Pa·s for soy and gelatin, respectively. Modulus of elasticity curves appeared only at the highest concentrations, which means that the formation of the continuous structure of film or coating occurs by different mechanisms depending on the biopolymer type and its amount dispersed in aqueous solutions. [ABSTRACT FROM AUTHOR]

Artificial neural networks have great prospects in solving the problems of predicting the properties of polymers. The purpose of this work was to study the possibility of using artificial neural networks to determine the rheological parameters of polymers from stress relaxation curves. The nonlinear Maxwell–Gurevich equation was used as the deformation law. The problem was solved in the MATLAB environment. The substantiation for the choice of the neural network input and output parameters was made. An algorithm for obtaining the data for neural network training was also proposed. Neural networks were trained on theoretical stress relaxation curves constructed with the Euler method. The value of the mean square error (MSE) was used as a criterion for the performance of the training. The constructed model of the artificial neural network was tested on the experimental relaxation curves of recycled polyvinyl chloride. The quality of the experimental curve approximation was quite good and was comparable with the standard methods for processing stress relaxation curves. Unlike the standard methods, when using artificial neural networks, no preliminary data smoothing was required. It is possible to use the proposed technique for processing not only relaxation curves, but also creep curves as well as processing creep tests not only in central tension, but also in bending, torsion and shear. [ABSTRACT FROM AUTHOR]

In this study, the usability of colemanite wastes (CW), in mortar mixtures, was examined in terms of compressive strength, while at the same time it was aimed to evaluate the effects of this waste on the rheological properties of mortar and paste mixtures. Mortar and cement paste mixtures were produced by substituting 1, 3, 5, and 7% of the cement with the CW. Marsh-funnel flow times, mini-slump values, rheological parameters, and setting times of cement paste mixtures containing CW were determined. The time-dependent slump-flow and 1-, 7-, 28-, and 56-day compressive strength values of the mortar mixtures were determined. The microstructures of the specimens were evaluated by using SEM images, and phase analyses were examined with XRD analysis. The results showed that the use of CW negatively affected the fresh state properties and rheological parameters of cementitious systems. However, CW addition decreased the 1-, 7-, and 28-day compressive strength. Only a slight increase was observed in the strength of mixtures containing 5 and 7% CW at 56 days. [ABSTRACT FROM AUTHOR]

The aim. To study the eff ect of cetostearyl alcohol (CSA) on the rheological properties of bases with diff erent dispersion media, the release of propylene glycol (PG) from them, and the ability of these bases to absorb water. Materials and methods. Micelles of a non-ionic surfactant and its aggregates with CSA in a mixed solvent where the structure of water prevails, mixed solvent PG – macrogol 400 (M400) and hydrophilic bases-vehicles with diff erent dispersion media were studied. The research was carried out by the spin probe method using a probe simulating a cationic surfactant and by rotational viscometry. The microstructure of the bases was studied by optical microscopy. The in vitro release test to study the release of PG and M400 from solutions and bases was performed using vertical diff usion chambers. The content of PG and M400 in the dialysate was determined by gas chromatography according to the validated analytical procedures. The absorption of water by solutions and bases was determined by dialysis through the membrane. Results. CSA, which was the part of the bases together with surfactants in certain ratios, was a signifi cant factor in increasing their rheological parameters, reducing the parameters of PG release during in vitro release tests, as well as reducing water absorption. The mechanisms of such infl uence are diff erent for bases with diff erent structures of the dispersion medium. In the bases, where the structure of water prevailed, lateral phase separation occurred in the supramolecular structures of surfactant and CSA with the formation of liquid domains of surfactant and solid domains of CSA, which contributed to the formation of coagulation structures. In the mixed non-aqueous solvent PG – M400, surfactant micelles and mixed aggregates of surfactant and CSA molecules were not formed; at 25 °C, surfactants and CSA became separate dispersed phases of suspensions, which contributed to the formation of gels. When CSA was added into an aqueous solution of poloxamer 338, PG, M400 and cationic surfactant, the fl ow behaviour changed, and the rheological parameters increased, which led to a decrease in the release rate and extended for PG and M400 as well as in the ability to absorb water. The rate and extent of PG release from the solution were greater compared to the M400 release. Conclusions. The addition of CSA in combination with surfactants into the bases for semi-solid preparations is a signifi cant factor for modifying their rheological parameters, the kinetics of PG release from them, and water absorption during experiments in vitro. The mechanisms of such an eff ect are diff erent and depend on the composition and structure of the dispersion medium of the base. [ABSTRACT FROM AUTHOR]

During well drilling in offshore conditions beyond the North of the Arctic Circle, there are often problems associated with deviations in the rheological parameters of the drilling mud as the temperature changes. Mud temperature in the upper part of the well in most cases is in the range up to 20 °C, whereas in the productive formation it is up to 80 °C and more. For such conditions, it is necessary to estimate the influence of temperature on the rheological parameters of drilling fluids, which is done in this paper. Compositions of water-based and hydrocarbon-based muds that may be used in the conditions of the offshore hydrocarbon fields were considered. The paper presents the authors' formula for a drilling mud that possesses more stable rheological parameters in the temperature conditions of the offshore oil field and is more environmentally friendly. The physical properties of the newly designed drilling mud were measured with laboratory equipment. Rheological investigations were carried out under varying temperatures up to 80 °C. The results of the experiments show the newly designed drilling mud to be more stable than its hydrocarbon-based analogue. Besides, the newly developed composition has a lower content of solid phase, which is also an important parameter for the process of sea wells construction, often characterized by a narrow window of permissible pressure. [ABSTRACT FROM AUTHOR]