Shear Stability Research Articles

Mechanism analysis of enhancing the temperature and shear resistance of hydroxypropyl guar gum fracturing fluid by boron-functionalized nanosilica colloidal crosslinker

With the increasing depth of reservoir development, the temperature and shear resistance of fracturing fluids needs to be further improved. In comparison with traditional crosslinking agents, nano-crosslinkers have superior crosslinking properties and can enhance the temperature and shear resistance of fracturing fluids. However, the synthesis of nano-crosslinkers is complicated and not sufficiently explained to elucidate the crosslinking mechanism. In this study, a nanosilica colloidal crosslinker with a larger size and more crosslinking sites was synthesized by a simplified method using nanosilica. The structure and crosslinking mechanism of nanosilica crosslinkers were explored using FTIR, XPS, TGA, and SEM. The results indicated that the nanosilica and organoboron were bonded through B-N bonds. The nanosilica crosslinker has good dispersion and excellent thermal stability. The thermal and shear stability of nano-crosslinked fracturing fluids was better than that of fracturing fluids formed with organoboron crosslinkers. Specifically, temperature resistance is enhanced by 7–18 °C and shear resistance by 5–20 mPa s. In addition, the gel-breaking fluid changes the wettability of the core surface and enhances the flow capacity of the oil. The results of FTIR showed the synergistic effect of hydrogen and covalent bonding between the crosslinker and guar gum molecules. The results of SEM indicated that the guar gum molecules are transformed from a linear structure to a membrane structure during the transformation of the fracturing fluid from a base fluid to a gel, which gave the gel water retention capacity and good proppant-carrying capacity. Furthermore, the nanosilica crosslinker is distributed on the surface of the membrane or located in the membrane by binding to the membrane. The interaction between the nanoparticles and the membrane structure enhances the strength of the membrane structure, which allows for better shear stability of the nano-crosslinked fracturing fluid at high temperatures.

Developing concentrated emulsion gel hybrids structured by natural food fibres

The integration of healthy unsaturated fat into plant-based meat alternatives is being advocated worldwide but remains technically challenging, due to limitations in the textural qualities and processability of edible oil. One way to improve the rheological behaviour of oil is via emulsion gel technology. However, adaptable solutions for real-life food processing are few and far between. On this basis, we formulated physically stable emulsion gel hybrid templates with 50–83% sunflower oil load, mostly oil-in-water microstructure, and structured solely by natural food fibres without using oleogelators. The fibres included citrus fibre and soy polysaccharides as emulsifying fibres, and curdlan and deacetylated konjac glucomannan as structuring fibres. Upon heating, they developed stiffness up to 10E4 Pa in storage modulus G′. Here, we present the first characterisation of such fibre-based emulsion gel hybrids through analysis by epifluorescence microscopy, oscillatory rheology, and diffusing wave spectroscopy, and report underlying composition-structure-rheology-thermal behaviour relations. The key findings are that strength in the emulsion gel hybrid could come from combinations of the following observed mechanisms: (i) tiny droplets of dispersed phase droplets with high curvature, (ii) emulsifying fibre of high molecular weight, (iii) controlled interference from emulsifying fibre on the viscoelastic network development of structuring fibre, and (iv) for additional shear stability, highly aggregated state of dispersed phase droplets without coalescence. Promising templates bearing close resemblance to animal fat references such as pork belly fat (in terms of G′), and shear stability with potential toward extrusion and food printing application have been identified.

3D nelinearna seizmička analiza i projektiranje izoliranih zgrada pri gibanjima tla s plitkim žarištem

The structural performance of base-isolated buildings during past earthquakes confirmed the suitability of Lead Rubber Bearing (LRB) isolators. To assess the effectiveness of such isolators, 3D base-fixed and associated base-isolated models of a multi-story building are performed for three components recorded at each of the three stations with the closest distances to the seismic fault of approximately 5.54, 11.39, and 17.82 km during the 6.7 Mw Northridge earthquake in 1994. In this study, we discuss important issues regarding the analysis and design of base-isolated buildings under near-field ground motions at both the Design Basis Earthquake (DBE) and Maximum Capable Earthquake (MCE) levels. The results demonstrate that although the shear strain and stability conditions are fulfilled, it is crucial to satisfy the rollout condition requirements because of the large isolator displacement at MCE level while utilising supplemental viscous dampers to improve the desired efficiency of isolation.

Application of engineering measures for the stabilization of the soil slope

Purpose. Analysis of the application of engineering measures to stabilize the soil slope with a building located near its edge using the Slide software package Methodology. To achieve this goal, calculations were made to determine the coefficient of slope stability when performing various engineering measures that would stabilize the slope and, if possible, save costs. In conditions of dense urban development, measures to stabilize the slope are chosen on the basis of not only taking into account geological conditions. It is necessary to analyze architectural solutions, landscape, the presence of neighboring structures, and so on. The method of round-the-cylindrical sliding surfaces is used, which is based on the calculation of possible sliding surfaces during displacements. The task of the calculation is to determine the stability coefficient of the slope for the most dangerous sliding surface. The results of the study. The calculated parameters of shear stability are determined: stability margin coefficient, coordinate of the sliding surface start, sliding depth, sliding surface end coordinate. To ensure the stability of the slope or slope, it is necessary that the stability margin coefficient is greater than 1, but it must be borne in mind that, depending on the class of responsibility of the structure, the required value of the stability reserve coefficient can be in the range of 1.25 – 1.80 and is regulated by the relevant type and class of construction standards (DBN). Scientific novelty. The possibility of predicting the behavior of natural slopes and artificial slopes in the process of their development and economic activity is obtained. Practical value. The used method of circular-cylindrical slip surfaces involves a large amount of monotonous calculations to determine the stability coefficient for each probable slip line and therefore the use of the software package will more effectively determine the parameters of slope stability, you can solve the issue of choosing the location of structures and designing measures to protect the territory from landslide processes on the slopes.

Mechanism and Performance Analysis of Nanoparticle-Polymer Fluid for Enhanced Oil Recovery: A Review.

With the increasing energy demand, oil is still an important fuel source worldwide. The chemical flooding process is used in petroleum engineering to increase the recovery of residual oil. As a promising enhanced oil-recovery technology, polymer flooding still faces some challenges in achieving this goal. The stability of a polymer solution is easily affected by the harsh reservoir conditions of high temperature and high salt, and the influence of the external environment such as high salinity, high valence cations, pH value, temperature and its own structure is highlighted. This article also involves the introduction of commonly used nanoparticles, whose unique properties are used to improve the performance of polymers under harsh conditions. The mechanism of nanoparticle improvement on polymer properties is discussed, that is, how the interaction between them improves the viscosity, shear stability, heat-resistance and salt-tolerant performance of the polymer. Nanoparticle-polymer fluids exhibit properties that they cannot exhibit by themselves. The positive effects of nanoparticle-polymer fluids on reducing interfacial tension and improving the wettability of reservoir rock in tertiary oil recovery are introduced, and the stability of nanoparticle-polymer fluid is described. While analyzing and evaluating the research on nanoparticle-polymer fluid, indicating the obstacles and challenges that still exist at this stage, future research work on nanoparticle-polymer fluid is proposed.

A simple analytical model for bamboo-reinforced slopes using modified Bishop method

Introduction: Embankments are constructed in many places for transportation purposes such as railways and roads. The stability of slopes in embankments has always been a concern, especially in cohesionless soils. There are many methods to increase the safety factor of cohesionless soil slopes using geogrids, geocells, concrete piles, and so on. The conventional material used to stabilize slopes has a huge impact on the environment. Nowadays, researchers are using natural fibers such as bamboo and coir fiber for stabilization purposes.Methods: In this paper, bamboo piles are used to stabilize slopes. The bamboo piles are inserted vertically on the slope face to increase the shear strength and stability against slope failure. A limit equilibrium method has been developed to estimate the stability of a slope improved by friction piles after modifying the Bishop method of slices. The stability of the slope is analyzed for both the reinforced conditions and the unreinforced conditions using the developed analytical formula.Results and Discussion: The analytical equations were developed by considering three modes of slope failure: shear failure of the bamboo piles along the failure surface, movement of the upper part of the soil, leaving the bamboo pile embedded in the base soil, and pulling out of the bamboo along with the upper part of the soil mass. Further validation of the results is carried out with the limit equilibrium method-based software SLOPE/W using a modified Bishop method. The factor of safety increased after reinforcing the slope with bamboo piles for all three modes.

Separation of La(III), Ce(IV) and Ca(II) from bastnaesite using acidic phosphonic chitosan and rotating disk membrane

The separation of rare earths is difficult due to their similar properties and the complex characteristics of associated vein ores. Complexation-ultrafiltration (CUF) and shear induced orderly dissociation coupling with ultrafiltration (SIODUF) were used to separate metal ions (M, M = La(III), Ce(IV) and Ca(II)) from simulated bastnaesite leaching solution using acidic phosphonic chitosan (aPCS) and rotating disk membrane. Effect of simultaneous removal of metallic ions was investigated by CUF, and suitable conditions were obtained for C/M 10.0 (mass ratio of complexant to metal ions) and pH 5.0. The shear stabilities of aPCS-M complexes were explored at different pH values and the results show that the complexes can dissociate at a certain rotational speed, the critical one. The critical shear rates of aPCS-La, aPCS-Ce and aPCS-Ca complexes at pH 5.0 were calculated as 1.42 × 105, 1.69 × 105 and 9.75 × 104 s−1, respectively. The order of complexes shear stability is aPCS-Ca < aPCS-La < aPCS-Ce. The high selective separation of M and regeneration of aPCS were achieved by SIODUF in the light of the difference of aPCS-M complexes shear stabilities. The separation coefficients βLa/Ce and βCa/La reach 31.2 and 53.9, respectively.

Potential of redcurrant protein-enriched fractions as emulsifier in oil–water-emulsions

Berry protein, due to its functional properties, was extracted from redcurrant pomace seeds (RPS) in aqueous media to utilise side-streams and increase the sustainability of food production. Emulsions containing 1% redcurrant seed protein and 10% rapeseed oil were prepared by high pressure homogenisation. The emulsions’ structure, droplet surface charge, stability, rheological behaviour, and colour were characterised by microscopy, dynamic laser light scattering, storage tests and bulk rheology including large amplitude oscillatory shear rheology, respectively. Protein extracts of RPS proved to stabilise oil–water-interfaces by formation of a protein film having non-linear flow characteristics. While at low to medium shear, the emulsions showed pseudoplastic behaviour, limited molecular mobility at the interface induced softening at high shear. The shear stability of the interfacial protein layer decreased with increasing pH, i.e. with increasing molecular charge. Emulsions were prone to flocculation and subsequent creaming, either because of low surface charge at low pH or due to bridging by proteins and polymerised polyphenol complexes under neutral conditions. Although redcurrants only occupy a small market share in the berry sector, they are of high importance for specialised local producers and results presented here might evince possibilities for the utilisation of other pomace types.

Prediction method for shear stability of composite hat-stringer stiffened panel

Prediction method for shear stability of composite hat-stringer stiffened panel

Fabrication of Pickering emulsions stabilized by citrus pectin modified with β-cyclodextrin and its application in 3D printing

Pickering emulsions stabilized by polysaccharide particles have received increasing attention because of their potential applications in three-dimensional (3D) printing. In this study, the citrus pectins (citrus tachibana, shaddock, lemon, orange) modified with β-cyclodextrin (β-CD) were used to stabilize Pickering emulsions reaching the requirements of 3D printing. In terms of pectin chemical structure, the steric hindrance provided by the RG I regions was more conducive to the stability of the complex particles. The modification of pectin by β-CD provided the complexes a better double wettability (91.14 ± 0.14°-109.43 ± 0.22°) and a more negative ζ-potential, which was more beneficial for complexes to anchor at oil-water interface. In addition, the rheological properties, texture properties and stability of the emulsions were more responsive to the ratios of pectin/β-CD (Rβ/C). The results showed that the emulsions stabilized at a φ = 65 % and a Rβ/C = 2:2 achieved the requirements (shear thinning behavior, self-supporting ability, and stability) of 3D printing. Furthermore, the application in 3D printing demonstrated that the emulsions under the optimal condition (φ = 65 % and Rβ/C = 2:2) displayed excellent printing appearance, especially for the emulsions stabilized by β-CD/LP particles. This study provides a basis for the selection of polysaccharide-based particles to prepare 3D printing inks which may be utilized in food manufacturing.

Preparation of degradable amphoteric surfactant and property evaluation of clean fracturing fluid

AbstractThe main agent of clean fracturing fluid, cationic quaternary ammonium salt surfactant, is difficult to degrade in natural conditions because of its long alkyl chain. In this study, a biodegradable amphoteric surfactant, stearate sulfobetaine (SESB), was synthesized by esterification of long‐chain stearic acid and N,N‐dimethyl ethanolamine followed by quaternization to serve as the main agent of clean fracturing fluid. The structure of the synthetic degradable surfactant was verified by infrared and 1H‐nuclear magnetic resonance spectroscopies. In addition, a series of indoor performance evaluations were carried out, including shear resistance, viscoelasticity, sand carrying capacity, and gel‐breaking performance. A series of experimental evaluations showed that the clean fracturing fluid prepared with 2% SESB and 0.4% EDTA‐4Na had an excellent comprehensive performance. The apparent viscosity was higher than 50 mPa s at 80°C for a shear rate of 170 s−1. It has good heat and shear resistance performance. In addition, the system processed high shear stability and recovery at room temperature. According to the viscoelastic test, the system mainly relies on elasticity to carry sand. The static settling velocity of sand was 0.042 mm/s under high‐temperature conditions of 95°C.

The physicochemical properties of a starch–sodium stearoyl lactylate complex formed via annealing treatment in ethanol solutions

This work examined the physicochemical properties of potato starch–sodium stearoyl lactylate (SSL) complexes formed by annealing potato starch with 0.6% SSL in different ethanol solutions (65–100%). The complexes exhibited a higher iodine binding capacity compared to annealed potato starch without SSL. The iodine binding capacity values of the complexes increased from 46.65% to 96.87% as the ethanol solution concentration decreased from 100% to 65%. Rapid viscosity analysis showed peak viscosities of the complexes ranging from 11 cP to 2012 cP and breakdown values of zero, indicating that the complex pastes showed both thermal and shear stability. Differential scanning calorimetry results showed an increase in the gelatinization temperature of starch treated in SSL–ethanol solutions (65–85%) and a decrease in enthalpy. The formation of complexes markedly decreased the swelling power and solubility of the starch granules. Overall, the starch–SSL complexes formed by annealing in ethanol solution had the performance characteristics of chemically crosslinked starch and have potential applications in high-temperature processed foods. • Annealing starch in ethanol solution with sodium stearoyl lactylate (SSL) was studied. • The disordered structure of amylose induced by SSL and ethanol was formed. • The formation of disordered structure complexes was affected by ethanol concentration. • The thermal stability of starch was enhanced by ethanol annealing treatment with SSL.

A bio-hydro-chemical model for gas pressure development in municipal solid waste landfills

Prediction of gas pressure development within municipal solid waste (MSW) landfills is of great importance for the stability analysis and design of gas collection systems. This study presents a fully coupled bio-hydro-chemical model for the gas pressure development in landfills. The reduction of foam on the relative gas permeability and the variation of the intrinsic permeability with degradation degree are considered. The source terms in the governing equations of two-phase flow and solute transport are chosen from the biodegradation process of MSW. Both one-step landfilling and multi-step landfilling are calculated to compare the differences. It is found that the fast hydrolysis of fresh MSW produces most of the volatile fatty acids (VFAs) and leachate within the first 2 months. During multi-step landfilling, the VFA and leachate produced from fresh MSW in the top flow downward to the bottom, leading to high gas production and high leachate saturation in the deep. Meanwhile, the high concentration of VFA reduces the surface tension of the leachate, enabling it to generate foam and further reduce gas permeability. Owing to the high gas production and low gas permeability, the excess gas pressure is easily developed in the deep layer. The maximum gas pressure of multi-step landfilling is about 2·5 times that of one-step landfilling. Case studies of the laboratory column test and in situ borehole test verify the accuracy of the model in predicting the temporal and spatial distribution of gas pressure. For the slope failure induced by high gas pressure, the evolution of shear strength and stability during a 2 year landfilling period is calculated and discussed.

Structure, thermal stability, and in vitro digestibility of rice starch–protein hydrolysate complexes prepared using different hydrothermal treatments

In this study, rice starch-protein hydrolysate (WPH-S) complexes with high resistant starch (RS) content were prepared by heat-moisture treatment (HMT) and annealing (ANN). The effects of different hydrothermal treatments on the structure and thermal stability of the WPH-S complexes and their relationship with starch digestibility were further discussed. The results showed that RS contents of ANN-WPH-S complexes (35.09–40.26 g/100 g) were higher than that of HMT-WPH-S complexes (24.15–38.74 g/100 g). Under hydrothermal treatments, WPH decreased the hydrolysis kinetic constant (k) of starch form 4.07 × 10−2–4.63 × 10−2 min−1 to 3.29 × 10−2–3.67 × 10−2 min−1. HMT and ANN promoted hydrogen bonding between WPH and starch molecules, thus increasing the molecular size of starch. In addition, the shear stability of WPH-S mixture was improved with the hysteresis loop area decreased after HMT/ANN treatments, resulting in a more stable structure. Most importantly, the hydrothermal treatment made the scatterers of WPH-S complexes denser and the surface smoother. Especially after ANN treatment, the WPH60-S complex formed a denser aggregate structure, which hindered the in vitro digestion of starch to a certain extent. These results enrich our understanding of the regulation of starch digestion by protein hydrolysates under different hydrothermal treatments and have guiding significance for the development of foods with a low glycemic index.

Shear and filtration strength of foundation of channel type hydropower plant building

The purpose of the study was to analyze the foundation's filtration strength and the HPP building's shear stability after 38 years of operation as part of the Tuyamuyun hydroelectric complex on the Amudarya River. The analysis was carried out based on field data obtained with the help of 16 piezometers installed in two alignments within the block of the HPP building and vertical drainages in the grassland. The constructed graphs of water pressure fluctuations in piezometers coincide with the nature of the change in the water level in the upper and lower pools. The actual gradients did not exceed the allowable gradient for the shaly sand interlayer and limestone bedding fracture filler. Comparison of the maximum natural gradients and those calculated from model studies using electrohydrodynamic analogies. The stability of the HPP building block is estimated by the maximum piezometric pressure and compared with analytical calculations, and the safety factor is 2.303. In this way, the base's filtration strength and the structure's shear stability are ensured in the entire range of changes in the operating mode of the pressure front of the HPP building block.

Shear recovery and temperature stability of Ca2+ and Ag+ glycolipid fibrillar metallogels with unusual β-sheet-like domains.

Low-molecular weight gelators (LMWGs) are small molecules (Mw < ∼1 kDa), which form self-assembled fibrillar network (SAFiN) hydrogels in water. A great majority of SAFiN gels are described by an entangled network of self-assembled fibers, in analogy to a polymer in a good solvent. Here, fibrillation of a biobased glycolipid bolaamphiphile is triggered by Ca2+ or Ag+ ions which are added to its diluted micellar phase. The resulting SAFiN, which forms a hydrogel above 0.5 wt%, has a "nano-fishnet" structure, characterized by a fibrous network of both entangled fibers and β-sheet-like rafts, generally observed for silk fibroin, actin hydrogels or mineral imogolite nanotubes, but generally not known for SAFiN. This work focuses on the strength of the SAFIN gels, their fast recovery after applying a mechanical stimulus (strain) and their unusual resistance to temperature, studied by coupling rheology to small angle X-ray scattering (rheo-SAXS) using synchrotron radiation. The Ca2+-based hydrogel maintains its properties up to 55 °C, while the Ag+-based gel shows a constant elastic modulus up to 70 °C, without the appearance of any gel-to-sol transition temperature. Furthermore, the glycolipid is obtained by fermentation from natural resources (glucose and rapeseed oil), thus showing that naturally engineered compounds can have unprecedented properties, when compared to the wide range of chemically derived amphiphiles.

Steady shear rheological properties, microstructure and stability of water in water emulsions made with basil seed gum and waxy corn starch or high pressure-treated waxy corn starch

The water in water (W/W) emulsions were prepared by mixing basil seed gum (BSG) with waxy corn starch (WCS) or high pressure-treated waxy corn starch (HWCS) at different concentrations. Increasing the concentration of WCS or HWCS increased the zeta potential, consistency index, infinite shear viscosity, and apparent viscosity, while it decreased the Z-average droplet size, polydispersity index, separation index, and flow behavior index of the W/W emulsions. After increasing the concentration of WCS and HWCS, the micrographs captured by an optical microscope indicated that the number of follicular droplets increased more than individual droplets. However, coalescence did not occur due to electrostatic repulsion. When the concentration of WCS and HWCS was increased from 0.5 to 2 wt% (at a constant concentration of 0.25 wt% and 0.2 wt% of BSG, respectively), the consistency index of the emulsions was increased significantly (p < 0.05) from 0.109 to 0.436 Pa. sn and from 0.032 to 0.743 Pa. sn, respectively. The results simply revealed the capability of 0.2 wt% BSG+ 0.5, 1, or 2 wt% HWCS and 0.25 wt% BSG+ 0.5, 1, or 2 wt% WCS for being utilized as stable W/W emulsions; these emulsions were stable for at least a week.

Гидравлический расчёт регулирующего сооружения, расположенного в ильменной части Прикаспийской низменности

Purpose: to solve the problem of conservation and reproduction of fish stocks of valuable commercial fish species in natural reservoirs, on the example of performing one of the tasks of developing a facility for regulating water regime of the ilmen part of the Volga delta. Using the well-known formulas of hydraulics, scientific developments of scientists in the field of hydraulic engineering and a priori information, it is necessary to determine the main parameters of a control structure located on a fishery reservoir in Astrakhan region. Materials and methods: a stage-by-stage hydraulic calculation of a tubular control structure that performs the functions of a water outlet was performed: the carrying capacity of the facility during operation in a pressure mode was determined; the main loads influencing the structure underground contour were determined by filtration calculation; a strength calculation of the floor for shear was performed. Results. A facility to regulate the water regime of the ilmen area of the Volga delta, ilmen, which are places of natural spawning grounds for commercial fish in Astrakhan region has been developed. The task of hydraulic calculation is to determine the conditions for the advancement of the filtration flow under the structure determining the pressure at characteristic points and to define the minimum dimensions of the floor that perceive stably the loads created by this flow. Conclusions. The calculation determined the main dimensions of the floor (length, width of the structure – 46.0; 4.65 m; length, thickness of the apron – 4.54; 0.3 m; length, thickness of the water apron – 4.8; 0.9 m; depth, water apron teeth width – 1.19; 0.40 m; length, thickness of the rear apron – 20.36; 0.6 m; length of the tubular part of the regulator – 16.3 m) taking into account the placement of gates, service and road bridges. The shear stability of the floor and the structure as a whole was determined.

Morphological and Functional Properties of Millet Starches as Influenced by Different Modification Techniques: A Review

AbstractThe growing need for new starches has sparked interest in the expansion of novel starch sources for the food sector. Millets are popular due to various health benefits and sustainability. Similar to the majority of cereals, the major constituent and quality factor of millet grain is its starch, which contributes 60—70% of the whole grain. Utilization of starch is reliant on its structural and functional properties. Starch in its native form does not possess all the required properties such as low temperature and shear stability. The desired properties for food products can achieved by modifying the starch functionality and morphology via physical, chemical, enzymatic, and dual methods. At present, research for potential application of native as well as modified millet starch is limited. The objective of this review is to focus on the techno‐functional and morphological properties, various modification techniques, and applications of the millet starches. The review paper also summaries the applications of modified millet starch in the food industry.

Plasma Instability During ITBs Formation with Pellet Injection in Tokamak

JET H-mode plasma discharge 53212 simulation during the pellet fueling operation in the presence of an internal transport barrier is carried out using the 1.5D BALDUR integrated predictive modelling code. The plasma instability during ITB formation with pellet injection in a tokamak is investigated. These simulations use a neoclassical transport model and an anomalous transport model (either multimode or mixed Bohm/gyro-Bohm core transport model). The boundary condition is described at the top of the pedestal, which is calculated theoretically based on a combination of magnetic and flow shear stabilization pedestal width scaling and an infinite-n ballooning pressure gradient model. The toroidal flow calculation is based on the neoclassical viscosity toroidal velocity model. It was found that the shallower pellet does not destroy the ITB, which locating mainly between r/a = 0.8 and 0.9. Moreover, in the plasma center region (0.4&lt;r/a&lt;0.6) the effective electron thermal diffusivities do not change during the ablation time. However, the effective electron thermal diffusivities decrease after pellet ablation, which means a shallower pellet can improve the internal transport barrier.