Low Shear Rates Research Articles

Reagent of Complex Action for Oil Transportation

Traditional methods of pipeline cleaning: scraping and heating of problem areas are quite timeconsuming and costly. Cost optimization in this area should be associated with the introduction of new high-tech technologies, as well as the use of effective domestic analogues of materials and components. Recently, the use of chemical reagents has become a method of influencing the rheological properties of the oil stream. It was found that solutions of the additive in toluene have optimal low temperature properties, which is obviously determined by its pour point (-95°C). The study of rheological properties was carried out at a low shear rate of 3.75 s-1, which corresponds to the starting loads on pumps of the oil pumping station, as well as in the range of shear rates at temperatures typical for gathering, infield and main oil transportation processes. Innovative methods for dealing with complications in oil transportation. Proposed by a number of developers, they are based on electromagnetic and ultrasonic treatment of the oil flow by stationary devices. Studies of dynamic viscosity during cooling in the temperature range from 70°C to minus 10°C made it possible to determine the depression of the saturation temperature of oil with paraffins in the presence of the developed reagent, which was 6°C, which reduces the cost of heating the oil-gathering header and infield pipeline when transporting oil in winter. At a low speed in the studied temperature range, the viscosity decreases by an average of 35%, which significantly reduces the starting loads on the pumps. This reagent may vary depending on the application conditions and reach 50% by weight. while maintaining the possibility of up to -30°C without preheating. The results show that the developed reagent effectively inhibits the formation of ASF in oils at economically reasonable concentrations of 100...200 g/m3 and is not inferior in efficiency to modern domestic and foreign analogues. On average, the intensity of the cleaning of pipes from the formed deposits will be reduced by 2.5 times.

Growth of Floc Structure and Subsequence Compaction into Smaller Granules through Breakup and Rearrangement of Aluminum Flocs in a Constant Laminar Shear Flow.

We have constructed an outer-cylinder-rotating Couette device for high-speed shear flow in laminar flow conditions and visualized the structure formation and subsequent rearrangement of PACl (flocculant made of aluminum hydroxide gel) and kaolinite flocs by visible light imaging. In a previous report, we analyzed the case of relatively low shear rate (G-value = 29 1/s) and confirmed that the flocculation process could be separated into two stages: a floc growth stage and a breakup/rearrangement stage. Once the large bulky flocs that reached the maximum size appeared, they rearranged and densified through structural fracture and rearrangement. In this report, this process was further investigated by conducting experiments under two different high shear rates (58 and 78 1/s) at which breakup and rearrangement became more pronounced, and three different aluminum kaolinite ratios (ALT ratios) that were over and under the optimum dosage (neutralization point by Zeta potential). Visualization results confirmed that, during the growth stage, the flocculation rate could be approximated by a scaling relationship between floc size and elapsed time, which depended on the ALT ratio. After reaching the maximum size, the floc rapidly became compact and dense following adsorption of the gel, incorporating fine fragments from erosion breakup. The over and under dosages created a lot of fragments of erosion breakup, but less so in the optimum dosage. In the optimum ALT ratio, fragments did not remain because they were incorporated into the flocs and densified, and the floc size was thought to be maintained. The floc circularity distribution peaked at around 0.6 and 1, suggesting that the flocs were spherical in shape due to erosion breakup.

Numerical investigation into effects of rheological properties on grout flow in rock fracture using Herschel-Bulkley model

Grouting is an essential technique for reducing the hydraulic conductivity and enhancing the strength of rock mass used in the Dongzhuang hydro-junction project. The rheological properties of grout are not to be disregarded during grouting. In this study, a numerical grouting model is established by combining a modified Herschel–Bulkley (HB) rheology model with the level set method. The effects of rheological parameters (power-law index n, consistency coefficient k, and yield stress τ0) on distribution pattern and flow characteristics of the grout are investigated. The HB model is more effective and precise than the Bingham model for predicting rheological characteristics. Numerical results indicated that distribution pattern and grout volume are primarily determined by n. A low shear rate inhibits the horizontal distribution and reduces the filling capacity of the grout, thus resulting in minimal deposition in the fracture. Grouts with a higher n and k require higher pressure to distribute around the fracture. The reduction in water volume in the fracture is calculated to provide comprehensive understanding into the sealing efficiency of the grout by varying the rheological parameters. This study provides valuable guidance regarding the different rheological parameter of grout in fractures, in addition to a novel concept for the optimal design of grouting distribution.

Methods to Measure Viscosity of Tiny Volumes of Oil With Blotter Paper

This article describes a method for measuring the viscosity of oils that behave as Newtonian at low shear rates, by using only 80 μl of oil. This method is particularly useful when only such small quantities of oil are available—for example, when oil is extracted from grease taken from bearings. The method consists in placing an oil drop on blotter paper where an oil stain will grow in time. The rate of growth is then a measure of viscosity. Master curves were generated expressing the relation between viscosity and oil stain growth, both at a given time and as a function of time, each with its own accuracy. The viscosity measurements with this method were compared with those obtained in a conventional viscometer using poly-alpha-olefin (PAO), ester, and mineral oils.

ВЛИЯНИЕ ГИПЕРРАЗВЕТВЛЕННОГО ПОЛИМЕРА НА ЗНАЧЕНИЯ ВЯЗКОСТИ ДЛЯ ТРУБОПРОВОДНОЙ ПЕРЕКАЧКИ ЖИДКИХ УГЛЕВОДОРОДОВ

The article presents the results of studies of the industrial hyperbranched polymer Boltorn W300 on the values of the dynamic viscosity of oil from Yakut fields in various concentrations and in different temperature ranges from 5 to 25 ° C in increments of 5 ° C, which can positively influence the processes of pipeline transportation of oils in conditions of complex rheological parameters of pipeline operation networks. A preliminary analysis of oil for physical and chemical properties was carried out and the rheological characteristics of the base oil were studied. It has been established that, according to the results of structural group analysis, the chemical composition of the oil is paraffinic. Using a rotational viscometer, the dynamic viscosity of the shear rate of an oil system containing an additive component in concentrations of 10, 30, 50, 80 and 100 ppm. It was revealed that the effectiveness of the hyperbranched polymer Boltorn W300 is observed only at low temperatures (below 10 0C); an increase in the effectiveness of the hyperbranched polymer Boltorn W300 from an increase in the concentration of the polymer additive in the oil system was also revealed. The most effective additive concentration in this study is 100 ppm, where the viscosity index is reduced by 40,7 %. The greatest effectiveness of the hyperbranched polymer Boltorn W300 in reducing dynamic viscosity and improving rheological properties is observed in the region of low shear rates - up to 3 s-1, which can be preliminarily assessed as a positive quality for use on pipelines for pumping oil media during the pipeline commissioning period, at which low shear rates are observed. shear rates and low oil flow rates.

Rationale for early rehabilitation of patients with uterine corpus cancer

To study the dynamics of hemorheologic changes and the frequency of early complications of laparoscopic radical hysterectomy in patients with uterine corpus cancer depending on conducting rehabilitation activities in the early postoperative period. The number of patients with uterine corpus cancer equal 49 (mean age 54.8±2.2 years), divided into 2 comparable groups, was examined: experimental group - 23 patients, who received local magnetotherapy since the first day after surgery for 5-6 days, and control group - 26 patients without physiotherapy. Comparative group included 24 healthy women. The basic rheological parameters, namely blood viscosity at high and low shear rate, hematocrit, erythrocytes' aggregation and deformability, erythrocytes and platelets electrophoretic mobility, were evaluated in all patients initially, on the 1st and 5th days after surgery and in comparison group. There were changes in the rheological properties of the blood before surgery in patients of both groups: increase of blood viscosity, enhancement of aggregation activity of its formed elements, decrease of erythrocytes' deformability properties. The laparoscopic radical hysterectomy was accompanied by the exacerbation of these disorders. The early magnetotherapy in patients reduced hemorheological abnormalities up to the preoperative parameters (p<0.05) for 5 days, as well as reduced the incidence of early postoperative complications by 2.4 times compared to the control group. The application of local low-frequency low-intensity magnetotherapy since the first postoperative day allows to reduce the level of postoperative hemorheological abnormalities up to the level of preoperative parameters, as well as the frequency of early postoperative complications.

Interplay between wall slip and shear banding in a thixotropic yield stress fluid.

We study the local dynamics of a thixotropic yield stress fluid that shows a pronounced non-monotonic flow curve. This mechanically unstable behavior is generally not observable from standard rheometry tests, resulting in a stress plateau that stems from the coexistence of a flowing band with an unyielded region below a critical shear rate c. Combining ultrasound velocimetry with standard rheometry, we discover an original shear-banding scenario in the decreasing branch of the flow curve of model paraffin gels, in which the velocity profile of the flowing band is set by the applied shear rate  instead of c. As a consequence, the material slips at the walls with a velocity that shows a non-trivial dependence on the applied shear rate. To capture our observations, we propose a differential version of the so-called lever rule, describing the extent of the flowing band and the evolution of wall slip with shear rate. This phenomenological model holds down to very low shear rates, at which the dimension of the flowing band becomes comparable to the size of the individual wax particles that constitute the gel microstructure, leading to cooperative effects. Our approach provides a framework where constraints imposed in the classical shear-banding scenario can be relaxed, with wall slip acting as an additional degree of freedom.

Reduced‐Order Models Unravel the Joint Impact of Aperture Heterogeneity and Shear‐Thinning Rheology on Fracture‐Scale Flow Metrics

AbstractSubsurface industrial operations often make use of complex engineered fluids. In fractured media, the hydraulic behavior of a geological fracture is affected by the shear‐thinning (ST) rheology of such fluids, depending on the imposed pressure gradient. Besides, owing to the stochastic nature of heterogeneities in the fracture's local apertures, obtaining the generic behavior of a fracture under ST flow requires large statistics of fractures whose aperture fields have the same statistical properties, namely their mean value, standard deviation, correlation length Lc, and Hurst exponent (which controls the scale invariances at scales smaller than Lc). The first such Monte Carlo study was recently proposed by Lenci, Putti, et al. (2022) using a new lubrication‐based model relying on a non‐linear Reynolds equation. This model describes the flow of an Ellis fluid, with both a low shear rate quasi‐Newtonian viscosity plateau and a large shear rate power law ST behavior, as measured for engineered fluids such as biopolymer solutions (e.g., xanthan gum). Here we aim to obtain the dependence of the fracture transmissivity and its dispersion over the statistics, as well as of the flow correlation length, on fracture closure, geometry correlation length, and applied pressure gradient, over a vast volume of the parameter space, and in a simple mathematical form. Employing reduced‐order models based on the polynomial chaos expansion theory to this aim, we discuss the properties of the obtained topographies of interest in the parameter space.

Microvascular Shunts, Intracranial Pressure, and the Impact of Drag-Reducing Polymers.

In the 50 years of my membership in ISOTT, I, Edwin M Nemoto, have enjoyed the application of many of the technologies developed in our society including microelectrodes for pH, PO2, and near-infrared spectroscopy (NIRS) in the measurement of tissue oxygenation and metabolism. The greatest joy has been the number of great scientists I have had the pleasure of knowing and exchanging scientific ideas with across the United States, Europe, and Asia. This will be the enduring legacy of ISOTT for me personally as we continue beyond our half-century existence.Every organ in our body, including the tegmentum, is endowed with microvascular shunts (MVS), which may be involved in physiological regulation, i.e. temperature regulation or pathophysiological responses to tissue injury and oedema. MVS that open in response to increased capillary resistance and tissue oedema in the brain, heart, kidneys, liver, and muscles conduct neither nutrient nor gas exchange with tissue promoting tissue oedema in a vicious cycle. Pharmacologic arteriolar vasodilation cannot correct the MVS flow as may occur after a stroke or traumatic brain injury because pan arteriolar vasodilation would shunt flow to the normal tissue and away from the injured brain in a "reverse" steal or a "Robin Hood" phenomenon. A high molecular weight (4000kDa) drag-reducing polymer (DRP) of polyethylene oxide or Lamiflo™ enhances blood flow by altering the physical dynamics of red blood cells (RBC) and blood flow, increasing the shear rate in the microvasculature and capillaries where shear rate is highest as it is inversely proportional to the 3rd power of blood vessel diameter. The shear rate sensed on the endothelium through the glycocalyx exerts precise control of endothelial function, including endothelial water permeability, nitric oxide synthase activity, lymphocyte adhesion to and transport across the endothelium, and microglial activation, all in response to low endothelial shear rate. DRP has proven effective in reversing MVS flow and increasing capillary flow in haemorrhagic shock, myocardial ischaemia, stroke, renal ischaemia, traumatic brain injury, stroke, sepsis, and Alzheimer's Disease. Our aim is to establish the universality of MVS in the pathogenesis of vascular disease and in taking DRP to clinical treatment of vascular diseases.

Molecular dynamics simulation of viscosity and rheology of nanofluids with single wall carbon nanotubes

The purpose of this work is to study the dependence of the viscosity and rheology of benzene-based nanofluids with carbon nanotubes on their length. The problem is solved by the method of nonequilibrium molecular dynamics; the rheology of nanofluids with single-walled carbon nanotubes with a length from 1.45 to 14.96 nm has been studied. The volume concentration of nanotubes was 2 %. It was established that at low shear rates nanofluids are Newtonian. Their viscosity significantly exceeds the viscosity of benzene, and this excess is not described by classical theories for coarse liquids. In addition, the viscosity of nanofluids significantly depends on the length of the carbon tubes and increases with their growth. Starting from a certain shear rate, nanofluids change rheology and become pseudoplastic. Thus, the change in rheology is a threshold phenomenon and the corresponding critical shear rates depend on the length of the nanotubes. At high shear rates, the differences between the viscosities of nanofluids with different nanotube lengths decrease monotonically. A correlation has been obtained that makes it possible to predict the viscosity of the nanofluid and the trend of its change depending on the shear rate and the length of the nanotubes.

Synthesis of silica bearing sulfobetaine and sulfonic groups and their electrorheological response

Organically modified silica bearing amino groups (SiO2-NH2) was prepared by the simple sol-gel procedure followed by treatment with butanesultone to produce zwitterionic silica bearing sulfobetaine groups (SiO2-SB). This particle was then treated with sulfuric acid to prepared particles carrying both sulfonic acid and ammonium salt (SiO2-SO3H). These particles were characterized by different methods and dispersed in silicone oil (15 wt%) to evaluate the electrorheological (ER) performance. Thermogravimetric (TG) analysis, zeta potential and Fourier transform infrared (FTIR) spectroscopy confirmed the structure of the modified silica. The ER response was evaluated using controlled shear stress (CSR) and oscillatory mode. The SiO2-NH2 and SiO2-SB based fluids displayed the highest shear stress at low shear rate even without an applied electric field. However the higher ER efficiency and lower leakage current was observed for the fluid containing SiO2-SO3H. From dielectric analysis, it was demonstrated that the zwitterionic SiO2-SB particle provided faster relaxation time and larger permittivity difference. Thus, it is possible to conclude that the lower viscosity of the SiO2-SO3H based fluid without electric field also plays an important role for a good ER efficiency. Both SiO2-SB and SiO2-SO3H particles are suitable for producing ER fluids due to their better dielectric properties and relaxation time. The former also presented better sedimentation stability.

Printed for Performance: Harnessing the Electrochemical Potential of Prussian White Thick Electrodes Via 3D Printing

The development of Prussian White (PW) water-based inks for thick, structured electrodes will be presented. Thicker electrodes (>100 µm) have the potential to have both high power and higher energy, however there is a trade-off between both. When increasing the thickness of a standard two-dimensional (2D) electrode this lengthens the ionic pathways, limiting our rate of ionic diffusion. To overcome these restraints, we can introduce a 3D architecture within the electrode microstructure to maintain favourable, short ionic pathways, whilst increasing the active surface area of the electrode.Here, we are investigating a high capacity, Na-ion material that is aqueous processed, to fabricate thick electrodes that can provide a high-capacity cell. PW is a Na-ion hexacyanoferrate crystal (NaxFe[Fe(CN)6]), where the redox properties of the iron atoms can be visualised in the voltage profile. PW has potential to be used for applications that Li-ion may not be necessarily required for, as it can reach a comparable capacity of 160 mAh/g, similar to that of LFP (Lithium iron phosphate). Moreover, this Na-ion material can overcome the supply and ethical issues that are currently associated with Lithium. Thus, PW here has the capability to become part of the next generation of batteries.To fully understand the PW electrochemical behaviour, the material underwent a baseline process. From our initial research, the moisture sensitivity of PW was observed clearly in the electrochemistry where sloping voltages and poor cell capacities were seen. Therefore, an effective drying process was developed to prevent the leaching of water molecules, thus allowing the full usage of the PW and now achieving the theoretical capacity of 160 mAh/g.PW was also examined via different mass loadings from 1-3 mAh/cm2, where we successfully demonstrated how thicker electrodes can provide a comparable cell capacity throughout, as shown by our electrochemical data. However, the limitations of thicker electrodes (3 mAh/cm2) were detected in the rate test data, where the PW experiences no capacity retention at high C rates, due to the limits of the elongated diffusion pathways in a 2D electrode. The GITT (galvanostatic intermittent titration technique) data visualised the diffusion mechanism of the thick PW electrodes, whilst from the EIS (electrochemical impedance spectroscopy) current density values were obtained.Thus, PW is being investigated here to see whether it has potential to be 3D printed via extrusion to create our desired structured electrodes. To understand how effectively an electrode ink will be printed, the rheology properties of the ink is also characterised here. The different parameters of achieving a high viscous ink at low shear rates, will also be discussed to allow the fabrication of thick, structured PW electrodes.With the initial 3D printed electrodes, the rate test data seen in Figure 1., the 3D printed electrodes hold a comparable capacity at low C rates, however, it is limited electrochemically at high C rates. It is clear that further optimisation of the ink rheology is needed and this can be done with the introduction of CNT (carbon nano tubes), higher solid content or using a secondary solvent to create an ink that is printable. Once structured electrodes are achieved through tuning the ink rheology and printing parameters, these electrodes will then be compared electrochemically against our standard 2D electrode, with hopes to overcome the ionic limits of thick 2D electrodes.The wider impact is that 3D printing via extrusion can be used for other materials, once a rheological checklist is passed. Thus, 3D printing has the potential to produce a cell with both high energy and power. The combination of Prussian White and 3D printing offers a promising method to developing novel electrode materials with enhanced performance for a range of electrochemical applications. Figure 1. Discharge capacities of PW9 (doctor blade) & 14.1 (3D printed) at different thicknesses, Na-half cell cycled between 1.3-3.8 V and discharged at C/5, C/2, C, 2C & 5C. Figure 1

Design and rheological behaviour of lactic acid based cholesteric liquid crystalline materials with hydroquinone unit in the molecular core

In order to contribute to molecular structure – physical property relationship for chiral self-assembling materials, two chiral compounds derived from the lactic acid have been designed. Mesogenic core of materials consists of two benzoate units and one hydroquinone unit connected by the ester linkage groups and two flexible alkyl chains. Different lengths of the chiral alkyl chain were tested, while the length of the achiral alkyl was kept same for all materials. The mesomorphic properties were established by polarizing optical microscopy and differential scanning calorimetry. Both materials possess reasonably broad and stable cholesteric (N*) phase down to room temperature. The rheological characterisation was performed in the N* phase on the compound with shorter chiral alkyl chain using a rotational rheometer in a plate/plate geometry with and without external electric field applied perpendicularly to the flow direction. The results reveal a shear thinning behaviour, even without electric field applied. The N* phase exhibits a slight electrorheological effect, at low shear rates, that continuously decrease with the increase of the shear rate, due to the competition of the flow and electric fields. The mesomorphic behaviour of the designed materials was compared to structurally similar materials. Quite broad temperature range of the N* phase down to room temperature makes studied lactic acid derivatives as suitable chiral dopants for design of new multicomponent mixtures targeted for various applications in photonics and optoelectronics.

Spreading ceramic stereolithography pastes: Insights from shear- and orthogonal-rheology

We study the shear rheological behavior of a commercial stereolithography paste containing ≈50 vol. % of zirconia particles (diameter ≈ 100 nm) with the aim to clarify physical mechanisms occurring during the “scraping” step of this yield stress fluid. Beyond a flow curve characterized by a high zero-shear viscosity accompanied with an overall shear-thinning behavior, we investigate in a systematic way the transient regime through start-up experiments. We demonstrate that a structural transition occurs between 10−2 and 10−1 s−1, resulting in an apparent interruption of the shear-thinning. The corresponding transient response presents a pronounced extra-growth of the shear stress before to stabilize at high strain amplitude and a negative first normal stress difference peak, both effects become stronger at higher shear rates. These observations are rationalized based on the high interparticle friction owing to the polyhedral shape and the roughness of the particles. In addition, relaxation tests following the start-up experiments reveal that the samples submitted to shear rates higher than 10−1 s−1 cannot relax the shear stress to the same level as in low shear rate experiments, suggesting a durable structural modification likely to impact the quality of the parts prior to their debinding and densification. Finally, we utilize orthogonal superposition rheology to illustrate how the application of an oscillatory deformation during the scraping procedure could help to reduce the shear-thinning interruption and improve the stereolithography processing as already observed empirically during scraping.

Rheology of dense suspensions of ideally conductive particles in an electric field

The rheological behaviour of dense suspensions of ideally conductive particles in the presence of both electric field and shear flow is studied using large-scale numerical simulations. Under the action of an electric field, these particles are known to undergo dipolophoresis (DIP), which is the combination of two nonlinear electrokinetic phenomena: induced-charge electrophoresis (ICEP) and dielectrophoresis (DEP). For ideally conductive particles, ICEP is predominant over DEP, resulting in transient pairing dynamics. The shear viscosity and first and second normal stress differences $N_1$ and $N_2$ of such suspensions are examined over a range of volume fractions $15\,\% \leq \phi \leq 50\,\%$ as a function of Mason number $Mn$ , which measures the relative importance of viscous shear stress over electrokinetic-driven stress. For $Mn &lt; 1$ or low shear rates, the DIP is shown to dominate the dynamics, resulting in a relatively low-viscosity state. The positive $N_1$ and negative $N_2$ are observed at $\phi &lt; 30\,\%$ , which is similar to Brownian suspensions, while their signs are reversed at $\phi \ge 30\,\%$ . For $Mn \ge 1$ , the shear thickening starts to arise at $\phi \ge 30\,\%$ , and an almost five-fold increase in viscosity occurs at $\phi = 50\,\%$ . Both $N_1$ and $N_2$ are negative for $Mn \gg 1$ at all volume fractions considered. We illuminate the transition in rheological behaviours from DIP to shear dominance around $Mn = 1$ in connection to suspension microstructure and dynamics. Lastly, our findings reveal the potential use of nonlinear electrokinetics as a means of active rheology control for such suspensions.

Extrapolation of classical rheometry of plant protein pastes to extrusion conditions

This study explores alternative methods to measure the rheology of pastes based on soy and pea proteins, which are commonly used as starting material in extrusion for the preparation of meat analogs. Currently, it is still a challenge to obtain consistent rheological data on such materials for steady shear at conditions that are relevant for the extrusion of such systems. Hence, possibilities are explored for the extrapolation of results obtained with classical rheometers operating at temperatures below boiling point, to conditions that are relevant for the extrusion of such systems. The above was combined, with findings from off-line and in-line capillary rheometers, which can provide steady shear measurements above boiling point and at hydration levels as used in extrusion.We have analysed the consistency of our new results with previous oscillatory shear measurements, performed at conditions similar to those of meat analog extrusion. For validation of the extrapolation we have analysed whether the new rheology data follow similar scaling rules. As classical rheometers can handle only moderate torques, the measurements are limited to hydration levels higher than those used in extrusion (75–85%). Despite this limitation, strain sweeps with classical rheometers show that in this regime the elastic modulus also scales with Tg/T, the ratio of glass transition, and actual temperature. Yet, its dependency on Tg/T appears differently from measurements performed at extrusion-like conditions. Moreover, our current results indicate a strong thixotropic nature of plant protein pastes at temperatures below boiling point. Consequently, flow curves are only stable if performed from high to low shear rates. Nevertheless, our data can be mapped to a single master curve following the Herschel-Bulkley model, with parameters also following a scaling rule dependent on Tg/T.This Tg/T scaling is used to construct master curves with data from the off-line and in-line capillary rheometers. The obtained shift factors for the flow curves are in agreement with old literature data obtained for SPI, but they deviate significantly from our steady shear measurements with classical rheometers. Based on the results of our current and previous study we have a critical, general discussion on the possibility of extrapolation of classical rheometry of plant protein pastes to process conditions used for production of meat analogs.

Experimental investigation of ice slurry viscosity

This work attempted to conduct an experimental study which demonstrates the effect of the initial concentration of solute on the apparent viscosity of ice slurry in a horizontal circular pipe. The study was conducted on ice slurry based on propylene glycol, varying from 5 to 24% with different ice mass fractions varying from 5 to 25%. During the experiments, the initial concentration of the propylene glycol, ice concentration, and flow rate was modified as parameters. The flow tests were performed on laminar flows. The results of the investigation revealed that the ice slurry behaved like a non-Newtonian fluid, while it sometimes behaved like a Newtonian fluid. The rheological behavior of the ice slurry is reflected by its viscosity. For the shear-thickening behavior, the apparent viscosity increases with increasing the shear rate, and for the shear-thinning behavior, the viscosity decreases with increasing the shear rate, while for the Newtonian behavior, the viscosity remains almost constant. Then it was revealed that the viscosity of the mixture became too high for low shear rates at high ice mass fractions by increasing the concentration of the solute. The power law was used to establish a relationship between the apparent viscosity and the indexes of flow and consistency of ice slurry.

Relationship between lipoprotein(a) and whole blood reducing viscosity: A cross-sectional study.

Lipoprotein(a) [Lp(a)] has been confirmed as a causal risk factor of atherosclerotic cardiovascular disease, but its role on circulation is not completely clear and is still being explored. Therefore, this study attempts to explore the relationship between Lp(a) and whole blood reducing viscosity (WBRV), to better understand the role of Lp(a) in circulatory and cardiovascular diseases. We retrospectively analyzed the data of consecutive subjects in the physical examination center of the Affiliated Hospital of Ningbo University Medical College from January 2022 to May 2022. Pearson or spearman correlation analysis was used to test the statistical relationship between 2 continuous variables according to whether they are normal; 131 participants were retrospectively enrolled in this study. The low-density lipoprotein concentration was associated with whole blood viscosity at low-shear (R = 0.220, P = .012), middle-shear (R = 0.226, P = .01), and high-shear viscosity (R = 0.212, P = .015), as well as plasma viscosity (RS = 0.207, P = .018). Lp(a) was not associated with whole blood viscosity at low, middle, and high shear rates, but was associated with WBRV at low shear (RS = 0.204, P = .019) and middle shear rates (RS = 0.197, P = .024). Lp(a) is associated with high WBRV, which may impart more insights into the role of Lp(a) in cardiovascular disease.

Time-dependent clay gels: Stepdown shear rate behavior, microstructure, ageing, and phase state ambiguity

To study the time-dependent properties of clay gels in the structural rejuvenation mode, a combination of the stepdown shear rate method and an ageing test is advocated. In this mode, the structural development process at two different initial equilibrium states during the low stepdown shear rate and the rest period of the ageing test were followed. The roles played by the electric double layer (EDL) repulsive force in this structural development process with and without shear, for platelet sodium montmorillonite or NaMnt, hectorite and Laponite gels, and fibrous sepiolite gels were assessed. The response of the stepdown shear stress and ageing yield stress reflects the action of these forces on the structural rejuvenation kinetics and the type of structure formed. The platelet clay gels with their strong EDL repulsive particle interaction commenced the structural development process immediately and formed an open network structure. This process is short in shear and takes years when without. The fibrous sepiolite gel with its weak EDL repulsive interaction did not display structural rejuvenation in shear and only showed a significant yield stress increase after the first few hours of ageing. An additional issue concerning the stability of the isotropic liquid (IL) phase state of dilute Laponite dispersions was addressed. These dispersions aged for &amp;gt;9 years, displaying that yield stress and network structure confirmed that the IL phase is unstable. A low energy path available for Laponite particles to aggregate was discussed. A new method for determining the flocculate phase state was also presented.

The effect of corrosion inhibitor chemistry on rheology and stability of CO2 and N2 acidic foam under harsh conditions

Utilization of CO2 foam in well-stimulation operations is a realistic practice to reduce carbon emissions by injecting CO2 into subsurface formations. The viscosity and stability of CO2 and N2 acidic foamed fluid is impacted by additives such as corrosion inhibitor and chelating agent and conditions such as pressure. In this study, the apparent foam viscosity was determined using a high pressure - high temperature foam rheometer at a temperature of 150 °C, pressure ranging from 1000–4000 psi, and different shear rates 100-2000 1/s. A foam analyzer was furthermore utilized to characterize foam properties such as foamability, foam stability, and bubble structures at 100 °C and 1000 psi. Different surfactants were used due to their ability to generate stable and viscous foam; Duomeen TTM, Ethoduomeen T13, Armovis VES, and the combination of Duomeen TTM and Armovis VES. Among all surfactants, Duomeen TTM provided the highest foam viscosity with CO2 at both low and high shear rate. Once the surfactant solution was mixed with 1.5 wt% of CI, the foam viscosity dropped sharply. However, the synergic surfactants (i.e., Duomeen TTM and Armovis VES) obtained the highest viscosity once mixed with CI. Also, the effect of CO2 and N2 at different pressures on the viscosity of generated foam was investigated. When the CO2 pressure was raised to 2000 psi, the viscosity of CO2 foam increased by 55% at both low and high shear. In comparison, the N2 foam viscosity increased by 12% at 100 1/s shear rate and by 32% at 1500 1/s. According to the findings, the influence of CI increased as the pH of the foam fluid declined, and thus reduced the foam viscosity. Finally, foam properties such as foamability, foam stability, and bubble structure were determined. N2 foam generated higher foam stability than CO2 foam. The findings of this study can help for a better understanding of the effect of corrosion inhibitor on CO2 and N2 foam viscosity at high temperature and pressure.