Pseudoplastic Fluid Research Articles

Convective heat transfer of electrically conducting MHD power law fluid through annular sector duct

This study deals with the effect of Lorentz force on forced convection flow of electrically conducting magneto-hydrodynamic, (MHD) power law fluid through the annular sector duct by using finite volume method. In existence literature, hydro-thermal flow of MHD power law fluid within an annular sector duct has not been reported. The effect of Lorentz force on hydro-thermal power law fluid flow makes it very much novel in its own right. Here the main objective is to explore the effect of Lorentz force on hydro-thermal flow characteristics. The influence of uniform magnetic field is taken parallel to the radial direction. The effects of Hartman parameter, [Formula: see text] and power law index, [Formula: see text], corresponding to Lorentz force and power law fluid respectively, on the quantities of interest such as velocity and temperature profiles, friction factor and average Nusselt number [Formula: see text] are discussed for different geometric configuration parameters’ values of the annular sector duct. Computer code is developed and validated by comparing the results of limiting cases with the available literature. It has been observed that [Formula: see text] increases with the increase in [Formula: see text]. This trend is prevalent in both pseudo-plastic and dilatant fluids. The impact of [Formula: see text] is pronounced in the later case.

Synthesis and characterization of in-situ self-growth mineralization-responsive dispersed gel nanoparticles

This study employed a reverse emulsion method to prepare dispersed nanoparticle gels that respond to mineralization and exhibit excellent characteristics such as small particle size, high dispersion, and strong stability by introducing catechol-like structures and temperature/salt-resistant functional monomers. Experimental results showed that the particle size of the dry dispersed gel particles ranged from tens to 100 nm, as observed by scanning electron microscopy. Laser particle size analyzer testing demonstrated that the size of the dispersed gel particles progressively increased with the mineralization degree of the dispersed particle gel, indicating a certain level of mineralization responsiveness. Additionally, these particles could maintain stable dispersion for up to 40 days in a solution with a mineralization degree of 20,000 mg/L. The rheology testing results indicate that the dispersed particle gels exhibited the properties of the pseudo-plastic fluid. Even under extreme conditions such as high temperature and mineralization, the strength of the dispersed particle gels remained intact, measuring 95.76 kPa after 40 days of aging. Using Materials Studio molecular simulation software, the stability and self-growth mechanism of dispersed gel particles were explained from the quantum mechanics perspective. The geometry of the dispersed gel particles was optimized using the Compass II force field, and the total energy of the model was calculated to be −757.579 kcal/mol, with the dihedral torsion energy contributing the most to the total energy. The molecular bond lengths in the polymer chain were then calculated, with the O–H bond being the shortest and the O-Na bond in the carboxylate sodium group being the longest. This indicated that the –OH group was more stable and the carboxylate sodium group was prone to hydrolysis, forming a –COOH group and increasing the dispersion stability. The charge distribution and molecular orbitals in the polymer molecule were also calculated, with the LUMO value being −7.405 eV and the HOMO value being −4.487 eV. This study used a reverse emulsion method to in-situ generate mineralization-responsive, multi-haired dispersed gel nanoparticles, which fundamentally solved the injection problem of low-permeability oil reservoirs and provided new materials for long-term plugging of high-temperature and high-salinity oil reservoirs.

Effect of heat treatment at low moisture on the increase of resistant starch content in Araucaria angustifolia seed starch

In order to investigate the physicochemical and structural properties and the in vitro digestibility, starch extracted from pinhão was submitted to modification by thermal treatment at low moisture and heating at 100 °C for 8 h. The swelling power and solubility at 90 °C were lower for the modified samples than in the native starch. The decrease displayed in the 1047/1022 cm−1 and 995/1022 cm−1 ratio values, identified by FTIR, suggested that the modification decreased the relative crystallinity, as confirmed in the X-ray analysis. The modification changed the crystallinity pattern of the starch granules, which shifted from type C, presented in the native starch, to type A in the modified samples. Microscopy revealed that the starch granules presented concavities and a tendency to agglomeration after modifications. The rheological properties showed that the starch gels behaved like pseudoplastic fluids. The apparent amylose content increased in the samples with modification moisture of 15, 20 and 25%. On the other hand, the RS content increased in all modified samples, with the sample with 35% modification moisture presenting the highest increase (17.73%) in relation to native starch.

Effects of fucoidan and ferulic acid on potato starch: Pasting, rheological and retrogradation properties and their interactions

The study aimed to investigate the effects of fucoidan (FU) and ferulic acid (FA) on the pasting, thermal, rheological, microstructural and moisture migration properties of potato starch (PS) gels. Pasting results showed that the presence of FU and FA significantly enhanced the thermal stability and resistance to breakdown, and inhibited the stickiness of starch, with the ternary system (PS-FU-FA) showing the best performance. Thermodynamic results indicated that the PS-FU-FA ternary system markedly reduced the retrogradation rate, with FA counteracting the aging phenomenon induced by FU. Rheological tests revealed that all gel systems exhibited weak gel and pseudoplastic fluid behaviors. FA increased the elasticity of PS gels, while FU and FU-FA reduced the viscoelasticity and thickening coefficient of PS, and improved its resistance to shear thinning. Scanning electron microscopy, infrared spectroscopy and low-field nuclear magnetic resonance results suggested that the changes in the above results were due to the interactions among FU, FA and PS, which increased the short-range order structure, and made the microstructure more uniform, compact and continuous, unfavorable for moisture movement, with better water-holding capacity and thermal stability. This study confirmed that the addition of FU and FA had positive effects on the gel properties of PS, providing new insights for the design strategy of starch-based foods, and promoting the practical application of FU, FA and PS in food industry.

Insight into the dissolution behaviour and rheological characterisation of lignin in 1-butyl-3-methylimidazole bisulphate-ethanol system

ABSTRACT Lignin dissolution and the fluid behaviour of reaction systems play important roles in the conversion rate of lignin. This study investigated the solubility of enzymatic hydrolysis lignin (EHL) in 1-butyl-3-methylimidazole bisulphate ethanol solutions ([BMIM]HSO4/ethanol) and the dynamic shear rheological characterisation of EHL-[BMIM]HSO4/ethanol. Different with [BMIM]HSO4/water, [BMIM]HSO4/ethanol exhibited excellent abilities to dissolve EHL at [BMIM]HSO4% 20%–90%, with the maximum EHL solubility obtained at 40%–70%. The dynamic shear rheological characterisation strongly depended on temperatures, [BMIM]HSO4% and EHL%, exhibited as pseudoplastic fluid at higher [BMIM]HSO4% and EHL%, and Dilatant fluid at lower [BMIM]HSO4% and EHL%. Adjusting an appropriate [BMIM]HSO4% and EHL%, EHL-[BMIM]HSO4/ethanol was Newtonian fluid with the viscosity stable. EHL was regenerated from EHL-[BMIM]HSO4/ethanol without obvious changes in the chemical structure and thermal behaviour. This study provided ideas for the design of the [BMIM]HSO4/ethanol system and the optimisation of conversion processes for the economic utilisation of lignin.

Non‐Newtonian laminar pulsating heat and fluid flow in plane duct

AbstractIn the present study, laminar pulsating power‐law momentum and heat transfer in a uniformly heated plane duct is studied analytically. Assuming that fully developed conditions exist both hydrodynamically and thermally, a perturbation series method is utilized to derive analytical solutions for the momentum and energy balance equations, and the amplitude is prescribed as the perturbation parameter. For varying values of the power‐law index (), representing pseudoplastic, Newtonian, and dilatant fluids, effects of dimensionless amplitude () and frequency () on periodic and period‐averaged friction factor and Nusselt number are obtained. The results obtained for Newtonian fluid are shown to be in good harmony with the corresponding findings in the open literature.

Numerical Simulations for Electro-Osmotic Blood Flow of Magnetic Sutterby Nanofluid with Modified Darcy's Law

Owing to the considerable significance of the combination of modified law of Darcy and electric fields in biomedicine applications like drug design, and pumping of blood in heart and lung devices; so, numerical and physiological analysis on electro-osmotic peristaltic pumping of magnetic Sutterby Nanofluid is considered. Such a fluid model has not been studied before in peristaltic. The applied system of differential equations is obtained by using controls of low Reynolds number and long wavelength. Simulations for a given system are counted using two high-quality techniques, the Finite difference technique (FDM) and the Generalized Differential transform method (Generalized DTM). Vital physical parameters effects on the profiles of velocity, temperature, and Nanoparticle concentration have schemed in two different states of Sutterby fluid, the first is dilatant fluid at β<0 and Pseudo plastic fluid at β>0. A comparison between the prior results computed by FDM and Generalized-DTM and literature results are given in nearest published results have been made, and found to be excellent. The discussion puts onward a crucial observation, that the velocity of blood flow can be organized by adaptable magnetic field strength. A drug delivery system is considered one of the significant applications of such a fluid model.

Characterization, bioactivity, sustained release capacity and digestive stability of acidic sugarcane leaf polysaccharide liposomes

Acidic sugarcane leaf polysaccharide (ASLP) has a variety of biological activities, but its macromolecular properties make it difficult for the human body to completely absorb or metabolize quickly in the body, and the action time is short. To solve this problem, acidic sugarcane leaf polysaccharide liposomes (ASLPL) were prepared by reverse evaporation method and characterized for encapsulation efficiency, particle size, potential, morphology, rheology and stability. In vitro release and digestion tests were used to verify the sustained release effect and stability of ASLPL. The results showed that ASLPL was spherical, with an encapsulation rate of 86.19% ± 0.976%, a particle size of 134.57 ± 2.501 nm, and a zeta potential of −24.49 ± 1.002 mV, which was a pseudoplastic fluid that was more stable to be stored in a neutral environment at 4 °C. The antioxidant, hypolipidemic and antibacterial activities of ASLPL were significantly increased compared with those of ASLP. The in vitro release and digestion results showed that ASLPL had obvious sustained release effect and could slow down the digestion of ASLP in vivo and prolong the duration of action. Therefore, the development and utilization of ASLPL can provide a greater development potential for the further application of ASLP in the food and pharmaceutical fields.

Development of New Dermato-Cosmetic Therapeutic Formulas with Extracts of Vinca minor L. Plants from the Dobrogea Region.

A new trend in the use of indole alkaloids from natural products is the preparation of topical pharmaceutical formulations with applications in the field of regenerative medicine. These formulations can be characterized through the ease of administration, the proven healing action of indole alkaloids, the protection of skin lesions, and the assurance of oxygen permeability. Based on the numerous benefits that indole compounds extracted from the Vinca minor plant show externally, the purpose of this study was to develop new semi-solid biocomposites for topical application obtained from hydroalcoholic macerates of 40%, 70%, and 96% concentrations from the stems and leaves of the Vinca minor L. plant from the Dobrogea area. A total of 12 pharmaceutical formulations (named P1-P12) were prepared for which the physicochemical properties, pH, thermal stability, spreading capacity, and rheological behavior were determined. The optimal formulas with antioxidant and antimicrobial capacity were evaluated and determined (P3, P4, P9, and P10). Antioxidant activity was elicited using the photochemiluminescence method. The microorganisms used for the evaluation of antimicrobial activity were Gram-positive Staphylococcus aureus (ATCC 25923), Gram-negative Escherichia coli (ATCC 25922), and a fungal species, Candida albicans (ATCC 900288). The study of the rheological profile for the obtained composites revealed Newtonian, pseudoplastic, and thixotropic fluid behaviors. Following determinations using the photochemiluminescence method, the best antioxidant activity was obtained in the P3 and P9 preparations. The results of the antimicrobial analysis confirmed that both the leaves and the stems of the Vinca minor plant represent a valuable source of antibacterial substances, and the biocomposites analyzed may represent an alternative in the realization of new pharmaceutical preparations with topical applications based on hydroalcoholic macerates obtained from the Vinca minor plant.

Investigating the influence of induced charge and surface charge heterogeneity on electrokinetic micromixing: A comparative analysis

This paper investigates the performance of a micromixer by considering the combined effects of surface charge heterogeneity and the induced charge electrokinetic (ICEK) phenomenon. With the applied electric field, surface charge heterogeneity generates a recirculation zone within the microchannel, while conductive links induce micro-vortices. The main objective is to explore the influence of various control parameters on the mixing efficiency, including zeta potential, the number and orientation of conductive links, and applied electrical potential. The generated recirculation zone and induced micro vortices introduce chaotic perturbations within the microchannel, improving mixing performance. The results demonstrate that increasing the zeta potential on heterogeneously charged patches enhances the mixing performance, albeit at the expense of a reduced average outlet velocity. Additionally, a higher number of conductive links leads to increased mixing efficiency. The combination of mounting a conductive link inside the channel and applying a heterogeneous zeta potential patch on the wall substantially increased mixing efficiency. The influence of fluid rheology on mixing performance is also investigated, revealing that pseudoplastic fluids exhibit better mixing than dilatant fluids. Finally, the combined effects of all parameters are evaluated using the Taguchi method, resulting in an optimized mixing performance for the proposed micromixer. Micromixing efficiency exceeding 98% is achieved for all types of non-Newtonian fluids under optimal parametric conditions.

A molecular study of viscosity-causing mechanism and viscosity reduction through re-emulsification for Jimsar shale oil

The high viscosity caused by oil–water emulsification and the lack of clarity on the viscosity-causing mechanism have seriously affected the development of Jimsar shale oil. In this paper, the mechanism behind the increase in viscosity due to emulsification for Jimsar shale oil is revealed at the molecular level, using high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with Electrospray ionization (ESI) technique. The high amount of N1 compounds (carbazoles and indoles) in shale oil combine with water through the N–H bond with the pyridine ring adsorbing formation water, which enhances crude oil's emulsification and water-binding ability. A stable W/O emulsion was formed with water and significantly increased the viscosity of the formation fluid. DFT calculations showed that the interaction energy (Eint) of anionic surfactant AS-1 and AS-2 with polar macromolecules was −258.70 and −77.03 kcal/mol, respectively. The interaction energy of these two systems was much lower than that between H2O and polar macromolecules (-50.87 kcal/mol). It indicated that AS-1 and AS-2 could penetrate the oil–water interface and form stronger interactions with polar macromolecules. Thus, the W/O emulsion is in a reversed-phase, and the viscosity is reduced. The laboratory results showed that the viscosity reduction rates (VRR) of AS-1 and AS-2 due to re-emulsification were greater than 94% at 30℃. The O/AS-1/W and O/AS-2/W emulsions formed during re-emulsification have pseudoplastic fluid flow characteristics and are relatively stable. The emulsions also exhibit spontaneous destabilization and water separation properties, lowering the cost of oil–water separation of produced liquid. Through weak dipole–dipole interaction, CH-π type interaction, and some weak interactions (O∙∙∙N, O∙∙∙S, O∙∙∙H), AS-1 and AS-2 make the space between crude oil and emulsion components more open and inhibit the aggregation of polar macromolecules furthering the viscosity reduction effect.

A non-Newtonian thermal lattice Boltzmann method for simulation of Rayleigh–Bénard convection of power-law fluids

Despite the widespread popularity of the Bhatnagar–Gross–Krook lattice Boltzmann (BGK-LB) model due to its simplicity and efficiency, its application in heat transfer involving non-Newtonian fluids (NNFs) has been limited by inherent constraints. This paper proposes a numerically stable BGK-LB model for the thermal flow of NNFs. The modified model incorporates the local shear rate into the equilibrium distribution function of the velocity field and addresses the numerical instability problems encountered in the traditional BGK-LB model under low viscosity conditions by introducing an additional parameter. In addition, a temperature evolution equation that can accurately recover the convective diffusion equation is adopted. The accuracy of the current method is validated by performing simulations of Rayleigh–Bénard convection (RBC) in a square cavity filled with Newtonian fluids and NNFs. Subsequently, simulations are conducted to investigate the behavior of RBC in power-law fluids. The analysis focuses on examining the impact of the Rayleigh number (Ra = 5 × 103 − 105) and the power-law index (n = 0.8–1.3) on the convective structure and heat transfer characteristics while maintaining a fixed Prandtl number (Pr = 7) and aspect ratio (L/H = 2). It is discovered that, for a given n value, the convection intensity and heat transfer rate increase with increasing Ra, which is supported by the increasing trend of the mean Nusselt number (Nū) with Ra. Furthermore, compared to NFs, pseudo-plastic fluids display a higher Nū value due to an augmented heat transfer rate, while dilatant fluids exhibit a lower Nū value owing to a diminished heat transfer rate.

De-branching of starch molecules enhanced the complexation with chitosan and its potential utilization for delivering hydrophobic compounds

The current study aimed to prepare the complexes between debranched-waxy corn starch and chitosan polymers (DBS-CS), and then investigated their corresponding structural characteristics, rheological property and potent application in Pickering emulsion. The results indicated that the existence of chitosan significantly inhibited starch short-range molecular rearrangement for all DBS-CS samples, which was manipulated by both debranching treatment and chitosan content. Interestingly, this is the first study to reveal that the outstanding peak at 1.8 ppm in 1H NMR spectrum for sample DBS-CS was gradually shifted towards a lower-field region following an increased chitosan content. Moreover, the debranching treatment shifted the crystallinity pattern from A-type to B-type and the relative crystallinity of DBS-CS decreased gradually with the increased content of CS. All samples had a pseudoplastic fluid and shear-thinning behavior with an enhanced shear resistance following the complexation. The DBS-CS was applied in a Pickering emulsion for showing a greater emulsifying stability and a lower gel strength than native NS-CS prepared emulsion. Importantly, the encapsulation ability of curcumin in the DBS-CS emulsion was significantly improved, followed by an increase of 15.45% for its corresponding bioavailability compared to the control. Therefore, this study might highlight a potential carrier for delivering the bioactive substances in a green pattern.

Effect Of Power-Law Fluids Flow Structures On Germicides Disinfection Through Taylor-Couette Configuration

Abstract Fluid disinfection involving ultraviolet rays (UV) is a promising method due to its easy implementation and low cost compared to other methods. In the present work, fluid disinfection in a Taylor-Couette configuration operating with power-law fluids with different absorbance coefficients,and fluence rates were simulated using the Lattice Boltzmann Method. The effects of operating parameters such as Taylor and axial Reynolds numbers, power-law index behavior, and fluence rate were analyzed. Results show that the required UV dose decreases for an increase in absorbance coefficient, while it grows for increasing power-law indexes. For T a = 120 and Re = 3, the disinfection reaches 82.3% for pseudo-plastic fluids and is complete for dilatant fluids. Considering different absorbance coefficients, it was observed that a = 0.4 leads to complete disinfection regardless of the fluid. For a = 0.5, fluid disinfection is complete for the dilatant fluid only. A value of 0.6 leads to partial disinfection (~90%) for all fluids.

Universal Strategy for Regulating Protein‐Based High Internal Phase Emulsions as 3D Printing Materials

AbstractProtein‐stabilized high internal phase emulsions (HIPEs), which are pseudoplastic fluids with shear thinning and high viscoelasticity, are suitable for 3D printing inks. However, owing to the lack of a universal approach to the 3D printing of HIPEs, existing printing materials are unable to meet the developmental, biocompatibility, and safety requirements of various applications. Herein, it is demonstrated that post‐acidification of protein HIPEs enhances 3D printing performance. This method has the advantage of breaking through protein limitations, pH, and other environmental factors. The self‐supporting property required for 3D printing is achieved through the self‐assembly of continuous‐phase proteins into particle aggregates, and interfacial stability is maintained owing to the constant interfacial tension and contact angle. The acid‐induced protein aggregates in the continuous phase do not affect the stability of the modified HIPEs. This work provides a valuable new idea for advancing the application of protein HIPEs in 3D printing through a post‐acidification strategy.

Study on the Effect of Ore-Drawing Shear Factor on Underground Debris Flow in the Block Caving Method

The shear factor of ore drawing is an important factor affecting the formation of underground debris flows. The aim of this study was to investigate the effect of the mining shear factor on underground debris flows in natural caving. The research background was the underground debris flow in the Plan copper mine, and we analyzed the characteristics of the slurry material structure of the underground debris flow, as well as the influence of the ore-drawing shear factor on the formation mechanism of the underground debris flow. The results showed that the slurry of the underground debris flow in the Plan mine is both a pseudoplastic and thixotropic fluid. Shearing force induced in drawing deforms the slurry and decreases its viscosity with the increase in shear rate and time. The shear force produced by the flow of ore particles first produces shear action on the paste in the shear boundary region of the ore drawing, reducing the paste viscosity while increasing its fluidity. Consequently, the “activation” makes the paste flowable, which flows along with the bulk ore flowing through the drawing mouth. The continuous ore-drawing process continuously shears the new moraine slurry in the ore-drawing channel and continuously “activates” the moraine slurry in the ore-drawing channel. Finally, destructive underground debris flow accident of a certain scale occurs. To our knowledge, this study thoroughly investigated the effect of the ore-drawing shear factor on the formation mechanism of underground debris flows, which not only broadens the research field of debris flow but also covers the deficiency of systematic research on underground debris flows, providing theoretical guidance for the prevention and control of underground debris flows.

Pseudoplastic liquid mulch film incorporating waste lignin and starch to improve its sprayability and available soil nitrogen

Because traditional slow-release fertilizers cannot effectively retain soil heat and moisture, their ability to increase crop yields is limited. To solve this problem, novel sprayable liquid mulch films (lignin-starch-acrylate, LSA) were prepared with a slow-release urea function, created by emulsion polymerization between lignin (extracted from papermaking waste liquor), starch, and acrylate monomers. The introduction of lignin transformed the LSA emulsion into a pseudoplastic fluid with enhanced sprayability. The presence of lignin in LSA film increased the elongation at break and lowered the Young's modulus, resulting in a film that is more easily pierced by crop seedlings and preserves the heat and moisture of the soil after seedling piercing. Experimental results showed that at a mass ratio of lignin to acrylate monomers of 3/7, the LSA mulch film had good sprayability and film-forming properties, suitable mechanical properties, and the lowest urea release rate. This optimized LSA film exhibited better soil insulation and water retention performance than other slow-release fertilizers. The contents of available soil nitrogen, including NH4+-N and NO3−-N, in soil covered with LSA film were 44.82 and 45.49% higher than those in soil covered with urea, respectively, and the corresponding cabbage yields increased by 33.73%. The results of this study provide a new method for preparing agricultural materials with urea slow-release as well as soil moisture and heat preservation functions.

Antiproliferative Imidazo-Pyrazole-Based Hydrogel: A Promising Approach for the Development of New Treatments for PLX-Resistant Melanoma.

Aiming at developing a dermal formulation against melanoma, the synthesized imidazo-pyrazoles 2-phenyl-2,3-dihydro-1H-imidazo[1,2-b]pyrazole-7-carboxylic acid (3-methoxy-4-phenoxy-benzylidene)-hydrazide (4G) and 2-phenyl-2,3-dihydro-1H-imidazo[1,2-b]pyrazole-7-carboxylic acid (4-benzyloxy-3-methoxy-benzylidene)-hydrazide (4I) were screened on patient-isolated melanoma cells (MEOV NT) and on Vemurafenib (PLX4032)-resistant (MEOV PLX-R) ones. Since 4I on MEOV PLX-R cells was 1.4-fold more effective than PLX, a hydrogel formulation containing 4I (R4HG-4I) was prepared in parallel with an empty R4-based hydrogel (R4HG) using a synthesized antibacterial resin (R4) as gelling agent. Thanks to its high hydrophilicity, porosity (85%), and excellent swelling capability (552%), R4 allowed to achieve R4HG and R4HG-4I with high equilibrium degree of swelling (EDS) and equilibrium water content (EWC). Chemometric-assisted ATR-FTIR analyses confirmed the chemical structure of swollen and fully dried (R4HG-D and R4HG-4I-D) hydrogels. The morphology of R4HG-D and R4HG-4I-D was examined by optical microscopy and SEM, while UV-vis analyses were carried out to obtain the drug loading (DL%) and the encapsulation efficiency (EE%) of R4HG-4I. Potentiometric titrations were performed to determine the equivalents of NH3+ in both R4HG and R4HG-4I. The swelling and water release profiles of both materials and related kinetics were assessed by equilibrium swelling rate and water loss studies, respectively, while their biodegradability over time was assessed by in vitro degradation experiments determining their mass loss. Rheological experiments established that both R4HG and R4HG-4I are shear-thinning Bingham pseudoplastic fluids with low yield stress, thus assuring easy spreadability in a future topical application. Release studies evidenced a sustained and quantitative release of 4I governed mainly by diffusion. Upon favorable results from further experiments in a more realistic 3D model of melanoma, R4HG-4I could represent a starting point to develop new topical therapeutic options to adjuvate the treatments of melanoma cells also when resistant to currently available drugs.

ИССЛЕДОВАНИЕ ПРОЦЕССА ВСПЕНИВАНИЯ БИТУМА В СМЕСИТЕЛЕ

The article discusses the main ways to save material, labor and financial resources in the production of asphalt concrete mixtures. It has been shown that a promising way to save energy and reduce harmful effects on the environment is to reduce the temperature of the bitumen. A foam generator design has been proposed that allows efficient mixing of bitumen with the generated steam. To describe rheology, the article uses the Ostwald-de Waele power-law fluid model. An expression for the current function is obtained, which allows to find the characteristics of the flow of the carrier phase in the mixer, taking into account the geometric parameters of the mixer, such as the diameter and length of the pipe, the radius of the screw, and the flow parameters at the inlet to the mixer. It is shown that under the same flow conditions, in order to obtain the same flow rate in the case of a pseudoplastic fluid, it is necessary to apply a greater pressure gradient compared to a Newtonian fluid. Experimental studies are carried out on the developed laboratory installation, which make it possible to determine the rational design and technical parameters of the foamed bitumen installation, the parameters of which are changed during the experiment. A regression equation is obtained in coded form, expressing the dependence of the quality of adhesion of foamed bitumen to inert material depending on the design and technological parameters of the developed bitumen foaming device

Effect of microwave followed by cooling on structural and digestive properties of pinhão starch

To increase its resistant content, native pinhão starch was modified using a microwave (300 W, 90 s) and subsequently cooled at 4 °C for 4, 8, 16, 24, and 72 h. The results demonstrated that all starches exhibited a crystalline structure of type C, with decreased crystallinity after modification. In the modified samples, the ratio of peaks 1047/1022 cm−1 and 995/1022 cm−1, as identified by FTIR, indicated a reduction in the crystalline region and damage to the double helix structure of starch granules. DSC analysis revealed that modified starches had lower gelatinization temperature range values due to the presence of more homogeneous crystals. Rheological analyses showed that starch suspensions obtained exhibited pseudoplastic fluid behavior and gel-like viscoelastic structure formation, with higher storage moduli in samples with longer cooling times. The microwave-modified starch, cooled for 72 h, exhibited higher digestion resistance, resulting in a 43.6 % increase in resistant starch content and a 26.1 % decrease in rapidly digestible starch compared to native starch. The results highlight that the modification of native pinhão starch using a microwave, followed by cooling at 4 °C for 72 h, presents a promising method for increasing the resistant starch content.