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Abstract Optical fiber technology is gaining increasing importance in all those fields requiring reliable, miniaturized, compact, and plug‐and‐play devices, with a special relevance in life science applications. Here, optical fibers are adopted to measure the fluids viscosity, by detecting the transit time (related to viscosity) of a steel bead moving through the tested fluid in a microfluidic channel under constant pressure. The proposed optofluidic system is designed by defining a theoretical model, here experimentally validated in the viscosity range of 5–110 cP, well resembling main blood flow features. The achieved results demonstrate the capability to work in multi‐point and single‐point detection modalities with a trade‐off between resolution (minimum of 10−1 and 1 cP respectively) and measurement time (tens of seconds and milliseconds range, respectively). An optimum accuracy close to 1.5% has been achieved, with room for further optimization by reducing bead size uncertainty. The proposed platform features simple, low‐cost, reliable, and fast measurements and ensures the integration with microfluidics chip in a miniaturized and disposable system. The low volumes required (scalable down to µL range) and the ease of use enable the translation of the proposed platform in clinical scenarios involving real‐time blood and plasma viscosity measurements under physiological conditions.

Conventional methods for measuring viscosity rely on macroscopic device components, which are difficult to miniaturize. The magnetic nano‐stirbars are small enough to enter tiny spaces and can spin without precise installation, making them an ideal candidate for exploring new methods. It is shown that a dense layer of Au nanowires can be grown on the silica surface of the nano‐stirbars, as a means to modulate the viscous resistance during their spinning and to make them visible under an optical microscope. The uniform growth of Au nanowires and the slight fluctuation of the spinning rates are investigated. It is shown that the nano‐stirbars with the hairy layer of Au nanowires can be used to measure the viscosity in microscopic liquid systems, such as microfluidic chambers and capillary tubes, involving cell media and blood samples. It is believed that the success with the proof‐of‐concept tests will open a window for further miniaturization of the nano‐stirbars for measuring in ultrasmall systems. [ABSTRACT FROM AUTHOR]

Introduction: There is clinical evidence that the fresh blood viscosity is an important indicator in the development of vascular disorder and coagulation. However, existing clinical viscosity measurement techniques lack the ability to measure blood viscosity and replicate the in-vivo hemodynamics simultaneously.Methods: Here, we fabricate a novel digital device, called Tesla valves and ultrasound waves-powered blood plasma viscometer (TUBPV) which shows capacities in both viscosity measurement and coagulation monitoring.Results: Based on the Hagen-Poiseuille equation, viscosity analysis can be faithfully performed by a video microscopy. Tesla-like channel ensured unidirectional liquid motion with stable pressure driven that was triggered by the interaction of Tesla valve structure and ultrasound waves. In few seconds the TUBPV can generate an accurate viscosity profile on clinic fresh blood samples from the flow time evaluation. Besides, Tesla-inspired microchannels can be used in the real-time coagulation monitoring.Discussion: These results indicate that the TUBVP can serve as a point-of-care device in the ICU to evaluate the blood’s viscosity and the anticoagulation treatment.

Abstract Conventional methods for measuring viscosity rely on macroscopic device components, which are difficult to miniaturize. The magnetic nano‐stirbars are small enough to enter tiny spaces and can spin without precise installation, making them an ideal candidate for exploring new methods. It is shown that a dense layer of Au nanowires can be grown on the silica surface of the nano‐stirbars, as a means to modulate the viscous resistance during their spinning and to make them visible under an optical microscope. The uniform growth of Au nanowires and the slight fluctuation of the spinning rates are investigated. It is shown that the nano‐stirbars with the hairy layer of Au nanowires can be used to measure the viscosity in microscopic liquid systems, such as microfluidic chambers and capillary tubes, involving cell media and blood samples. It is believed that the success with the proof‐of‐concept tests will open a window for further miniaturization of the nano‐stirbars for measuring in ultrasmall systems.

It is extremely important to gather the viscosity behavior of fluids accurately for industries and academia. There is no better method than viscosity measurement to detect changes in the specific characteristics of the materials. However, viscosity measurement is indeed a very sensitive process. In nature, fluids are involved in widely various containers, and they are affected by serious temperature deviations. It is a necessity for viscometers to have the capability to obtain accurate data from all types of containers of fluids even in serious temperature variations in order to understand the natural phenomena inside the fluids. Conventional viscometers mainly neglect the effect of sudden temperature deviations inside the fluids, or they need to use very expensive water bath systems that stabilize the temperature around the test fluids, which is not feasible at all. In this research, the effects of non-uniform temperature fields are analysed detailly to confirm that even in extremely limited amounts, serious viscosity and temperature deviations may occur. Experiments were performed in two parts. The first part was conducted using several thermocouples with different test fluids to find out the effects of thermal conduction and convection. For the second part, particle image velocimetry (PIV) was utilized to comprehend the flow movement within the test fluids. It was shown that even for small volumes and even in very controlled environments, an almost 35% viscosity measurement error (VME) occurs. Finally, as a solution to this problem, a new non-dimensional parameter called the Akpek number was proposed. The Akpek number enables the estimation of VMEs in any possible case. VME is a very crucial obstacle that has urgency to be illuminated by researchers and scientists to improve fluid characteristics. The main goal of this research is to illuminate the importance of this problem and offer a potential solution. The final results are supported by experimental data and numerical simulations using OpenFOAM. [ABSTRACT FROM AUTHOR]

Measuring the shear viscosity of polymeric melts is an extensive effort frequently performed in high-pressure capillary rheometers, where the pressures required to push the melt through a capillary at various temperatures and volumetric flow rates are recorded. Then, the viscosity values are obtained through Bagley and Weissenberg–Rabinowitsch corrections involving parameter fitting. However, uncertainties in those conversions due to pressure variations and measurement inaccuracies (random errors) affect the accuracy of the consequently calculated viscosities. This paper proposes quantifying them through a propagation of uncertainties calculation. This has been experimentally demonstrated for a polycarbonate melt. In addition, the derived viscosity uncertainties were used for the weighted residual sum of squares parameter estimation of the Cross-WLF viscosity model and compared with the coefficients obtained using the standard residual sum of squares minimization approach. The motivation was that, by comparison, individual poorly measured viscosity values should have a less negative impact on the overall fit quality of the former. For validation, the rheometer measurements were numerically simulated with both fits. The simulations based on the Cross-WLF fit, including the derived viscosity uncertainties, matched the measured pressures ~16% more closely for shear rates below 1500 1/s. Considering the uncertainties led to more precise coefficients. However, both fits showed substantial deviations at higher shear rates, probably due to substantial non-isothermal flow conditions that prevailed during these measurements. A capillary rheometer experiment was also simulated using arbitrarily chosen Cross-WLF parameters to exclude such systematic errors. A normally distributed error was then applied to the simulated pressures before re-fitting the parameters. Again, taking advantage of the derived viscosity uncertainties, the fit could recover the initial parameters better. [ABSTRACT FROM AUTHOR]

In this study, the electrical conductivity of low‐volume samples was measured using a prototype microfluidic chip with electrodes. We were able to show the difference of electrical conductivity in the samples of saline solution (0.9w/v% NaCl solution) with sucrose. The correlation between the electrical conductivity and the viscosity evaluated by the capillary method was shown. This correlation was shown that it is possible to evaluate viscosity based on the Walden's rule with our chip. [ABSTRACT FROM AUTHOR]

This study aims to analyze the used lubricating oil of small Diesel engines under different conditions in order to monitor their instant health condition, indicate their useful life, and provide early warnings of failure progress. It is an attempt to monitor different oil properties together with oil contaminants to diagnose the possible failures before occurring and identify their root causes. It is an effective tool in the case where there are no historical data records for the engines. Specifically, used lubricating oil samples from eight Diesel-powered engines are analyzed as an important information source for early failure detection and decision support. Oil properties; kinematic viscosity, density, and total acidic number (TAN) were analyzed. Also, oil contaminants; wear debris particles, soot, and water content were also elucidated in attempting to predict engine health conditions, wear mechanisms, and useful life. Scanning Electron Microscope (SEM) was used to analyze the wear debris particles. The root causes of engine failure were specified using the 5 Why’s method, and interviews with specialists, while the results were schematically presented using the Fishbone diagram. The analysis of oil viscosity showed that engines of high capacities performed better at high operating temperatures than small engines. Besides, the large oil imperfections are not directly related to the oil viscosity reduction but to the high oil TAN and the type and concentration of the oil impurities. This work analysis could assist in robust decision-making on the engine health condition, service life, and maintenance activity that should be applied. [ABSTRACT FROM AUTHOR]

It is extremely important to gather the viscosity behavior of fluids accurately for industries and academia. There is no better method than viscosity measurement to detect changes in the specific characteristics of the materials. However, viscosity measurement is indeed a very sensitive process. In nature, fluids are involved in widely various containers, and they are affected by serious temperature deviations. It is a necessity for viscometers to have the capability to obtain accurate data from all types of containers of fluids even in serious temperature variations in order to understand the natural phenomena inside the fluids. Conventional viscometers mainly neglect the effect of sudden temperature deviations inside the fluids, or they need to use very expensive water bath systems that stabilize the temperature around the test fluids, which is not feasible at all. In this research, the effects of non-uniform temperature fields are analysed detailly to confirm that even in extremely limited amounts, serious viscosity and temperature deviations may occur. Experiments were performed in two parts. The first part was conducted using several thermocouples with different test fluids to find out the effects of thermal conduction and convection. For the second part, particle image velocimetry (PIV) was utilized to comprehend the flow movement within the test fluids. It was shown that even for small volumes and even in very controlled environments, an almost 35% viscosity measurement error (VME) occurs. Finally, as a solution to this problem, a new non-dimensional parameter called the Akpek number was proposed. The Akpek number enables the estimation of VMEs in any possible case. VME is a very crucial obstacle that has urgency to be illuminated by researchers and scientists to improve fluid characteristics. The main goal of this research is to illuminate the importance of this problem and offer a potential solution. The final results are supported by experimental data and numerical simulations using OpenFOAM.

Efforts have been devoted to synthesize and characterize processable polymers with desired properties. Herein, four different series of aromatic and aliphatic terpolyamides were prepared via solution phase polycondensation of 4,4′-oxydianiline and hexamethylenediamine (HMDA) with various diacids chlorides (isophthalyol dichloride, terepthalyol dichloride, 1, 1′-ferrocene dicarboxylic acid chloride and trans-azobenzene-4, 4′-dicarbonyl chloride). The structural, morphological and physico-chemical nature of as prepared polymers was explored by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermal analysis (TGA and DSC), and wide-angle x-ray diffraction. Moreover, an aliphatic diamine was incorporated in varying concentration as a flexible methylene spacer and the effect of its concentration on the properties of polyamides was also studied. Changes in various physico-chemical properties such as solubility, inherent viscosity, surface morphology and flame retarding behaviour were investigated. Marked difference in morphology and solubility was observed with the change in the ratio of segments in the chain. Inherent viscosities of polymers ranged from 1.8052–1.6274 dl/g indicating reasonably moderate molecular weights. Interestingly, ferrocene based aromatic polymers were more thermally stable (Tg 260 °C, Ti 310 °C, Th 525 °C, Tf 720 °C, for PF0), and also found to exhibit best flame retarding behavior (limiting oxygen index value for PF0is LOI 33.15%). [ABSTRACT FROM AUTHOR]

Measuring the shear viscosity of polymeric melts is an extensive effort frequently performed in high-pressure capillary rheometers, where the pressures required to push the melt through a capillary at various temperatures and volumetric flow rates are recorded. Then, the viscosity values are obtained through Bagley and Weissenberg–Rabinowitsch corrections involving parameter fitting. However, uncertainties in those conversions due to pressure variations and measurement inaccuracies (random errors) affect the accuracy of the consequently calculated viscosities. This paper proposes quantifying them through a propagation of uncertainties calculation. This has been experimentally demonstrated for a polycarbonate melt. In addition, the derived viscosity uncertainties were used for the weighted residual sum of squares parameter estimation of the Cross-WLF viscosity model and compared with the coefficients obtained using the standard residual sum of squares minimization approach. The motivation was that, by comparison, individual poorly measured viscosity values should have a less negative impact on the overall fit quality of the former. For validation, the rheometer measurements were numerically simulated with both fits. The simulations based on the Cross-WLF fit, including the derived viscosity uncertainties, matched the measured pressures ~16% more closely for shear rates below 1500 1/s. Considering the uncertainties led to more precise coefficients. However, both fits showed substantial deviations at higher shear rates, probably due to substantial non-isothermal flow conditions that prevailed during these measurements. A capillary rheometer experiment was also simulated using arbitrarily chosen Cross-WLF parameters to exclude such systematic errors. A normally distributed error was then applied to the simulated pressures before re-fitting the parameters. Again, taking advantage of the derived viscosity uncertainties, the fit could recover the initial parameters better.

Correctness and reliability of molar mass data by viscometry in organometallic solvents (cuen, cuoxam, cadoxen) are compromised by the alkalinity of these solvents which causes immediate depolymerization especially in the case of pulps with higher carbonyl content (oxidative damage). The viscosity values thus correspond to the molar mass after the beta-elimination reactions that underly these degradative processes, which is sometimes significantly smaller than the molar mass determined by gel permeation chromatography (GPC) in the non-degrading solvent system DMAc/LiCl. Despite this well-known drawback, viscosity measurements have become a standard approach for molar mass measurements due to their ease and fastness, especially in the pulp and paper industries. A potential way to reduce the inherent error of these molar mass determinations via viscosity measurements is a reductive treatment prior to dissolution of the pulp in the organometallic solvents, which converts the labile, alkali-sensitive carbonyl structures back to the respective alcohols. Using sodium borohydride (NaBH4) on different types of cellulosic pulps, we demonstrate the beneficial effects of such a reduction step on the determined degree of polymerization (DP) for all three common solvents: cuen, cuoxam and cadoxen. Molar mass distributions and profiles of carbonyl groups were determined by GPC and by carbonyl selective fluorescence labeling ("CCOA method"). Such a reductive treatment was especially valuable for hemicellulose-containing pulps. While the decreased measurement error according to the new protocol is beyond doubt, an immediate acceptance in the pulp and paper industries is at least questionable, because the new, more correct data would not agree with the old – wrong, but consistent – numbers accumulated over years and decades. In the long run, however, the new, improved protocol will prevail here as well due to its lower error rate. [ABSTRACT FROM AUTHOR]

Viscosity measurement using a cone‐and‐plate rheometer is considered to provide an objective and reliable evaluation of thickening agents for dysphagia management. Here, we showed its measurement uncertainty in the context of an inter‐laboratory study. Eight test samples (i.e., four viscosity standard liquids, one xanthan gum reagent powder, and three commercial thickening agent powders) were distributed to 10 laboratories in a blinded manner. According to the same standard operating procedure, each laboratory dissolved the xanthan gum or thickening agents at four concentrations (0.5–4.0 g/100 g) and then measured their viscosity (35–803 mPa∙s). As for the viscosity of the standard liquids, the grand means were 98–100% of the certified values, and the relative standard deviations for repeatability (RSDr) and reproducibility (RSDR) were ca. 1% and ca. 5%, respectively, suggesting good accuracy in the measurement process. On the other hand, as for the viscosity of the thickening agents, RSDr and RSDR were ca. 2–6% and ca. 5–8%, respectively; however, heterogeneity in the preparation process comprising a manual dissolving step may increase these to near 60%. Furthermore, RSDr and RSDR of estimated additive concentrations to achieve targeted viscosities (50–500 mPa∙s) based on concentration‐viscosity curves were ca. 1–3% and ca. 3–5%, respectively, with a few exceptions. These findings suggest that a strictly standardized procedure provides reliable data on the viscosity measurements for thickening agents. [ABSTRACT FROM AUTHOR]

Introduction: There is clinical evidence that the fresh blood viscosity is an important indicator in the development of vascular disorder and coagulation. However, existing clinical viscosity measurement techniques lack the ability to measure blood viscosity and replicate the in-vivo hemodynamics simultaneously. Methods: Here, we fabricate a novel digital device, called Tesla valves and ultrasound waves-powered blood plasma viscometer (TUBPV) which shows capacities in both viscosity measurement and coagulation monitoring. Results: Based on the Hagen-Poiseuille equation, viscosity analysis can be faithfully performed by a video microscopy. Tesla-like channel ensured unidirectional liquid motion with stable pressure driven that was triggered by the interaction of Tesla valve structure and ultrasound waves. In few seconds the TUBPV can generate an accurate viscosity profile on clinic fresh blood samples from the flow time evaluation. Besides, Tesla-inspired microchannels can be used in the real-time coagulation monitoring. Discussion: These results indicate that the TUBVP can serve as a point-of-care device in the ICU to evaluate the blood's viscosity and the anticoagulation treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chen, Xia, Zhu, Xu, Cai and Shen.)

• Particle migration is a function of shear time, leading to a variable viscosity. • Particle migration is affected by several factors, e.g., rotational speed. • Critical shear time depends on the operational conditions. • A size segregation of the initially homogeneous system is observed. • A small gap width is suggested for viscosity measurement. A Discrete Phase Model (DPM) is adopted to investigate the particle behavior during viscosity measurement of solid-bearing slags. The particle-particle interaction is interpreted by the Discrete Element Method (DEM). The results show that the particle migration is a function of shear time, leading to continuous changes in variable viscosity before a critical shear time. The critical shear time and therefore the viscosity measurement depend on the operational conditions through the particle migration behavior that is influenced by the shear time, rotational speed, gap width and particle content, shape and size. The study of particle size indicates a size segregation of the initially homogeneous system. Based on our results a number of guidelines are formulated to assist in developing more reproducible viscosity measurement methodologies. [ABSTRACT FROM AUTHOR]

The mechanical properties of biological cells, especially the elastic modulus and viscosity of cells, have been identified to reflect cell viability and cell states. The existing measuring techniques need additional equipment or operation condition. This paper presents a cell’s viscoelasticity measurement method based on the spheroidization process of non-spherical shaped cell. The viscoelasticity of porcine fetal fibroblast was measured. Firstly, we introduced the process of recording the spheroidization process of porcine fetal fibroblast. Secondly, we built the viscoelastic model for simulating a cell’s spheroidization process. Then, we simulated the spheroidization process of porcine fetal fibroblast and got the simulated spheroidization process. By identifying the parameters in the viscoelastic model, we got the elasticity (500 Pa) and viscosity (10 Pa·s) of porcine fetal fibroblast. The results showed that the magnitude of the elasticity and viscosity were in agreement with those measured by traditional method. To verify the accuracy of the proposed method, we imitated the spheroidization process with silicone oil, a kind of viscous and uniform liquid with determined viscosity. We did the silicone oil’s spheroidization experiment and simulated this process. The simulation results also fitted the experimental results well.

• 1st a new device for the measurement of damped torsional oscillation is experimentally characterized and theoretically modeled. • 2nd a device for the measure of viscosity in liquids is fabricated and applied to monitor milk viscosity as function of fat content and temperature. • 3rd the main novelty consists in the fact that the measurement is performed by detecting the logarithmic decrement of oscillation as damped by the viscous forces. • 4th the magnetoelastic sensor operates outside the liquid to be monitored thus avoiding any contamination or inferences. • 5th the proposed device enables to have good viscosity determination at low share rate, in the range where standard rheometer fail. A new application of a high sensitivity magnetoelastic resonator able to measure period and damping constant of low frequency torsional oscillation is described and validated by experimental tests. The sensitive parameter is the amplitude of resonant magnetoelastic waves in the soft ferromagnetic core (Fe 62.5 Co 6 Ni 7.5 Zr 6 Cu 1 Nb 2 B 15 amorphous ribbon). The theoretical model of the device has been developed, correlating torsional oscillations to the friction force applied by the fluid in which they occur. Thus, an accurate indirect evaluation of fluid viscosity has been demonstrated. The main prerogative of the proposed sensor is to work without contact with the oscillating mechanism. As experimental validation, viscosity of UHT milk was measured versus different fat content. The experimental comparison with a standard rheometer demonstrates the new device competitiveness in the measure of low viscosity fluids at low share rate. Moreover, the detected behaviors at increasing temperature are in agreement with previous literature. In perspective, the new magnetoelastic resonators application can be very ductile and effective in on-line monitoring of viscosity change with time to control composition, degradation or contamination of liquids. [ABSTRACT FROM AUTHOR]

1-((E)-3-(4-bromophenyl) -1-phenylallylidene)-2-(m -tolyl)hydrazine (4) was synthesized and characterized for structural elucidation by spectroscopy (FT-IR, 1H NMR, and 13C NMR) and single crystal X-ray diffraction. In the title compound, the benzene rings A, B, C were oriented at dihedral angles {A/B = 82.92 (3)°, A/C = 24.12 (3)°and B/C = 75.90 (3)°}. Crystal structure showed that intermolecular C H⋯O and C H ⋯ N hydrogen bonds linked the molecules, enclosing R 2 2 (10) and R 2 2 (16) ring motifs. The Hirshfeld surface analysis of the crystal structure indicated that the most important contributions for the crystal packing were from H⋯H (46.0%), H⋯C/C⋯H (17.6%), H⋯Br/Br⋯H (12.4%), H⋯O/O⋯H (8.5%) and C⋯C (6.6%) interactions. Hydrogen bonding and van der Waals contacts were the dominant interactions in the crystal packing. Compound's interaction with DNA was further investigated theoretically by DFT and experimentally by UV–visible spectroscopy and cyclic voltammetry. DFT analysis in terms of geometry optimization and computed parameters revealed reactive nature of 4 and the possibility of planar phenyl rings to intercalate within the DNA base pairs. Spectral and voltammetric analysis and related binding parameters suggested intercalation as a possible mode for 4 – DNA binding which was further verified by viscosity measurements. A new compound 1-((E)-3-(4-bromophenyl) -1-phenylallylidene)-2-(m -tolyl)hydrazine was synthesized and studied for X-ray, Hirshfeld surfaces, DFT and DNA binding analysis. • 1-((E)-3-(4-bromophenyl) -1-phenylallylidene)-2-(m -tolyl)hydrazine - A new chalcone Schiff base. • Crystal structure determination. • Hirshfeld surface analysis. • DFT and experimental studies for DNA binding. [ABSTRACT FROM AUTHOR]

• Use of a continuously repeated chirp to form a pseudo-standing wave for viscosity measurement. • In-situ real time Newtonain viscosity measurement using non-invasive ultrasound. • Shear standing wave used to increase sensitivity of viscosity measurement. • Acoustic matching layer significantly improves ultrasonic viscosity measurement. The ability to monitor the viscosity of lubricating oils within metallic products is of interest to many industries, these being the automotive, aerospace and food industries to name a few. Acoustic mismatch at the metallic-liquid interface restricts ultrasonic signal transmission and so limits applicability and sensitivity of the technique. In this work, we propose the use of a continuously repeated chirp (CRC) shear wave to amplify the measurable acoustic response to liquid viscosity. The technique enables multiple reflections to superimpose inside the component and form a quasi-static standing wave whose amplitude spectrum depends on the condition at the solid-liquid boundary. Bare element shear ultrasonic transducers of 5 MHz resonant frequency were bonded to the lower surface of an aluminium plate in a pitch-catch arrangement to measure liquid in contact with the upper surface. Transducers were pulsed using a continuously repeated frequency sweep, from 0.5 to 9.5 MHz over 10 ms. The amplitude spectrum of the resulting standing wave was observed for a series of standard viscosity oils, which served as a calibration procedure, from which the standing wave reflection coefficient (S), was obtained. Measurements of 17 blended oils ranging in viscosity from 1080 to 6.7 mPa s were made. The technique was also evaluated with the addition of a polyimide matching layer (ML) between the metallic and liquid interface. Ultrasonic viscosity measurement values were then compared to measurements made using a conventional laboratory viscometer. The CRC method was found to significantly improve the sensitivity of viscosity measurement at a metal-liquid interface when compared to a single frequency burst with the benefit of low cost signal generation and acquisition hardware requirements. The CRC method is also capable of instant rapid response measurements as the signal responds in real time without the need to wait for a returning pulse. [ABSTRACT FROM AUTHOR]

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Highlights • A new pitch-catch scheme to excite and receive a relatively pure quasi-SH0 wave in the U-shape strip waveguide was proposed. • The viscosity of surrounding fluid can be quantitatively monitored based on the attenuation measurement of guided wave. • The performance of the U-shape waveguide sensor was evaluated in a wide range of viscosity (1cp-1600 cP). • The potential application of the U-shape waveguide sensor for high temperature (20℃–80℃) fluids was also presented. Abstract The shear horizontal (SH) wave in plate waveguides is of great advantage in fluid viscosity measurement as it only has in-plane displacements and causes a pure shear leakage in fluids, while the current excitation of non-dispersive SH waves in the strip with a finite width is very limited. In this work, we proposed a new pitch-catch scheme to excite and receive a relatively pure quasi-SH 0 wave in the U-shape strip waveguide. Based on the attenuation measurement on the quasi-SH 0 wave immersed in a viscous fluid, the viscosity of the fluid can be quantitatively monitored. Firstly, the wave field of the excited quasi-SH 0 was analyzed by using finite element simulations and the results demonstrate the effectiveness of the excitation method we proposed. Then, the U-shape waveguide sensor for viscosity measurement was presented, and a series of experiments were conducted on different concentrations of glycerol-water solutions with different viscosity (1cP-1600cP) under a wide temperature range (20℃–80℃). By calibrating the measured attenuation curves, the viscosity can be derived and the measurement uncertainty is less than 6% referring to a standard rotational viscometer. The proposed shear horizontal waveguide sensor is mechanically robust and quite suitable for online monitoring of fluid viscosity in industrial applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Viscosities of CO 2 -saturated squalane was measured from 0.1 MPa to 10.1 MPa at temperatures of 313 K, 333 K and 353 K. • Viscosities measured with the capillary viscometer match with literature data. • Acoustic levitation has been proven to be a promising method. Abstract Viscosity measurements with CO 2 -saturated squalane with three different methods, a novel and two classical ones, are compared in a range of pressure from 0.1 MPa to 10.1 MPa at temperatures of 313 K, 333 K and 353 K. The dynamic viscosities were measured using an acoustic levitator developed for measurements under pressure, a capillary viscometer and a rotational viscometer. Squalane is saturated with CO 2 at each pressure and temperature measured. It is shown, that the measured data are in good agreement with the values published by Dilchert. With the comparatively fast measurement time, the acoustic levitation has been proven to be a promising method. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an online viscosity measurement method based on the electromechanical impedance (EMI) of a piezoelectric torsional transducer. During testing, the contact torsional resonance of the cylindrical rod or host structure system is actuated and sensed by the ring array of shear mode piezoelectric patches. According to the quantitative electromechanical equivalent model we derived, the viscous damping from the contact fluid can be obtained by tracking the change of the piezoelectric impedance. A series of viscosity measurements was conducted on glycerol–water solutions of various concentrations, and the measurement results agree well with that given by standard laboratory viscometers. As the torsional vibration is a pure in-plane shear mode, which is more sensitive to the viscous damping and features a high quality factor, the proposed EMI-based measurement method is effective and promising for online viscosity measurement, especially for medium to high viscosity fluids. [ABSTRACT FROM AUTHOR]

The first goal of this study is to identify the ideal piezoelectric material for the manufacturing of rheological reflectance ultrasonic sensors. The second goal is to integrate the ultrasonic rheometer within a gas absorption reactor and to measure viscosity changes in an ionic liquid (IL) caused by gas absorption. To achieve the objectives, bismuth titanate, lead titanate, lead metaniobate and lead zirconate titanate materials in layer, tungsten bronze and perovskite structures were assembled on aluminum delay lines and tested under thermal cycling between room temperature and 150 °C. The results showed that lead metaniobate in tungsten bronze structure is the most suitable material for long time duration thermal cycling. Therefore, the ultrasonic rheometer was assembled using this material and installed in a pressurized reactor to test a reference IL at the operating conditions of 50 °C and at a pressure of 80 bar. The reference IL was saturated with nitrogen as well as hydrogen gas. Viscosity signals remained constant under the hydrogen atmosphere, while in nitrogen atmosphere the absorption of the gas lead to a rise in the value of viscosity.

This paper discusses a state-of-the-art inline tubular sensor that can measure the viscosity–density ( ρ η ) of a passing fluid. In this study, experiments and numerical modelling were performed to develop a deeper understanding of the tubular sensor. Experimental results were compared with an analytical model of the torsional resonator. Good agreement was found at low viscosities, although the numerical model deviated slightly at higher viscosities. The sensor was used to measure viscosities in the range of 0.3–1000 mPa·s at a density of 1000 kg/m3. Above 50 mPa·s, numerical models predicted viscosity within ±5% of actual measurement. However, for lower viscosities, there was a higher deviation between model and experimental results up to a maximum of ±21% deviation at 0.3 mPa·s. The sensor was tested in a flow loop to determine the impact of both laminar and turbulent flow conditions. No significant deviations from the static case were found in either of the flow regimes. The numerical model developed for the tubular torsional sensor was shown to predict the sensor behavior over a wide range, enabling model-based design scaling.

This paper reports on a new system for liquid density and viscosity measurement based on a freely suspended rectangular vibrating plate actuated by piezoelectric ceramic (PZT) actuators. The Lamb mode used for these measurements allows us to infer both the density and viscosity in a larger range as compared to the existing gold-standard techniques of MEMS resonators. The combination of the measured resonance frequency and quality factor enables extraction of density and viscosity of the surrounding liquid. The system is calibrated while performing measurements in water glycerol solutions with a density range from 997 to 1264 kg/m3 and viscosity from 1.22 to 985 mPa·s, which is a larger dynamic range compared to existing mechanical resonators showing an upper limit of 700 mPa·s. The out-of-plane vibrating mode exhibits quality factor of 169, obtained in deionized water (1.22 mPa·s viscosity), and 93 for pure glycerol with a viscosity of 985 mPa·s. This Lamb wave resonating sensor can achieve measurement in fairly large viscosity media while keeping a quality factor superior to 90. Measurements performed on oil validate the use of the Lamb system. Oil density is evaluated at 939 kg/m3 and dynamic viscosity at 43 mPa·s which corresponds to our expected values. This shows the possibility of using the sensor outside of the calibration range.

Viscosity of intestinal contents is known to affect digestion and absorption of nutrients. In most poultry studies, intestinal viscosity has been measured only after complete removal of solid particles by centrifugation. Centrifugation may however remove particles that contribute to viscosity, hence giving rise to an underestimation of viscosity. Two viscosity measurement techniques, one including a centrifugation step (Brookfield) and the other without (Haake), were compared in-vitro to assess whether both techniques result in similar conclusions regarding viscosity in feedstuffs. Two sets of feedstuff preparations were used. The first set was prepared with different combinations of milled feedstuffs in order to have a wide range of viscosity: 100% corn, 25% corn + 75% wheat, 100% wheat, 90% wheat + 10% rye, all mixed with distilled water. In the second set, barley was incubated with different beta-glucanases, and soybean and sunflower meal were incubated with different pectinases, again all mixed with distilled water. Viscosity was assessed using both techniques (Haake and Brookfield equipments) at six different time points. To evaluate the extent of agreement between the two methods, the Lin's concordance correlation coefficient (CCC) was assessed using the percentage of increase in viscosity within each method, based on pairwise feedstuffs comparison (first set), or relative to the feedstuff without enzyme (second set). The rate of the agreement between the two methods was substantial for the first set of feedstuffs (66%) and for the barley diets incubated with beta-glucanases (69%), whereas the CCC score for the soybean meal diets was very poor (2%) and fair for the sunflower meal diets, incubated with pectinases (32%). The lack of agreement for the latter can be explained by the limited variation in viscosity in these low-viscous mixtures. Although the two techniques are considerably different (e.g. with or without preceding particle removal), they seem to render similar conclusions when applied to poultry feedstuffs to identify distinct differences under the tested circumstances. [ABSTRACT FROM AUTHOR]

Viscometric properties of polymer are explored by the many-body dissipative particle dynamics (MDPD) using Lees–Edwards boundary conditions. The equation of state for the MDPD system is modified by fitting the density correction to different values of the cut-off radius. Due to the many-body interactions in MDPD, the viscosity contributed from the conservative force increases considerably with increasing repulsive coefficient, density and cut-off radius, and cannot be ignored compared to the ‘standard’ DPD case. The influence of these parameters on the MDPD viscosity is investigated, and we propose an equation to predict the viscosity in MDPD model. Additionally, the dumbbell polymer suspension model is investigated in the MDPD fluid, and the relations concerning first normal stress difference and shear rate, the relaxation time and spring constant, are consistent to theoretical works. We conclude that the MDPD model can be used to investigate the dynamics of non-Newtonian droplets. [ABSTRACT FROM PUBLISHER]

Viscosity of liquids is an important property determining flow characteristics such as shear stress caused by a flow, and elongation and dripping of films and drops. Conventional techniques determine liquid viscosity from shear stress acting in a capillary tube, on a vibrating plate, or on a rotating cylinder. The disadvantages of the methods are its relatively long measurement time and large amount of samples required, and more importantly, its inapplicability for coagulating liquids whose viscosity increases with time. Here we develop an original liquid viscosity measurement technique that employs a drop impact on a solid surface. The measurement principle is based on the energy budget: An impacting drop spreads on a solid surface due to kinetic energy which is on the surface converted to the viscous dissipation and the surface tension energy. We can therefore deduce the viscosity from the inertial, the surface tension force and the maximum spreading diameter. The simplicity of the present technique enables us to overcome the problems of the conventional methods. In experiments, we measured the viscosity of glycerol aqueous solution drops using a high-speed camera and a laser sensor. In conclusion, we revealed the uncertainty of the present technique is approximately 10%, which was evaluated both by uncertainty analysis and by experimentally comparing the viscosity with the ones obtained with an Ostwald viscometer. [ABSTRACT FROM AUTHOR]

Measuring of fluid properties such as dynamic viscosity and density has tremendous potential for various applications from physical to biological to chemical sensing. However, it is almost impossible to affect only one of these properties, as dynamic viscosity and density are coupled. Hence, this paper proposes kinematic viscosity as a comprehensive parameter which can be used to study the effect of fluid properties applicable to various fluids from Newtonian fluids, such as water, to non-Newtonian fluids, such as blood. This paper also proposes an ideal microplatform, namely polymeric suspended microfluidics (SPMF³), with flow plane orthogonal to the bending plane of the structure, along with tested results of various fluids covering a wide range of engineering applications. Kinematic viscosity, also called momentum diffusivity, considers changes in both fluid intermolecular forces and molecular inertia that define dynamic viscosity and fluid density, respectively. In this study a 3D suspended polymeric microfluidic system (SPMF3) was employed to detect changes in fluid parameters such as dynamic viscosity and density during fluid processes. Using this innovative design along with theoretical and experimental results, it is shown that, in fluids, the variations of fluid density and dynamic viscosity are not easily comprehensible due to their interconnectivity. Since any change in a fluid will affect both density and dynamic viscosity, measuring both of them is necessary to identify the fluid or process status. Finally, changes in fluid properties were analyzed using simulation and experiments. The experimental results with salt-DI water solution and milk with different fat concentrations as a colloidal fluid show that kinematic viscosity is a comprehensive parameter that can identify the fluids in a unique way using the proposed microplatform. [ABSTRACT FROM AUTHOR]

The viscosity of complex, anisotropic fluids, such as liquid crystals or their colloidal suspensions, is characterized by a number of coefficients. Methods to measure them are, typically, sensitive only to their particular combinations, hence unable to determine them individually. Using an Ericksen-Leslie model and propagation of light through aligned layers of such materials, we show theoretically and verify experimentally how this degeneracy can be lifted by exploiting both the amplitude and frequency of the voltage applied to the cell as control parameters. [ABSTRACT FROM AUTHOR]

The challenges of future regarding the energy supply are linked to the limitation of fossil fuels, the avoidance of climatic relevant gases, and the worldwide increasing demand for energy. Therefore, the future energy supply is characterized by the increase of renewable energy: sun, water, wind and biomass. Entrained flow gasification of biomass is promising, since it is a highly efficient and flexible process. Low-grade fuels are chemically transformed at high temperatures (>1200 °C) and pressures (up to 80 bar) into synthetic fuels. The inorganics of the fuel are converted into a slag, which forms a layer in the reactor. The thermophysical and chemical properties of the slag are defining the conditions and limitations of the gasification process. In this study, the fundamental thermophysical properties of bioliq slags are determined, in order to describe the heat transfer and the flow of the slag across the reactor by CDF-modelling of the bioliq-gasifier within the HVIGasTech project. By using a high temperature viscometer the viscosity and flow behavior of the slag were determined. In addition, the density and surface tension were measured by the sessile drop method. Thermometric and calorimetric methods were used to provide a detailed view onto the slags heat capacity and phase transitions. Thermodynamic calculations using FactSage and an in-house developed thermodynamic database for available solution phases and compounds were performed to obtain information about the ash-slag transformation. [ABSTRACT FROM AUTHOR]

In this paper, we report the characterization of the viscosity of biodiesel produced from jatropha curcas . The viscosity measurement has been carried out by using a modified falling ball viscometer as well as optical technology. The viscosity was measured from 28 to 70 °C, which is the interest for determining the quality of biodiesel. We found that the falling ball optical viscometer offers a resolution of a viscosity measurement of ±0.039 mPa s with a relative error of 1.47933%. The measurement process was compared with a commercial viscometer, and it has been demonstrated that the biodiesel produced in Chiapas has good quality. [ABSTRACT FROM AUTHOR]