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"The viscosity of the blood in narrow capillary tubes" by Robin Fåhraeus and Torsten Lindqvist (Am J Physiol 96: 562-568, 1931) can be a valuable opportunity for teaching basic hemorheological principles in undergraduate cardiovascular physiology. This classic paper demonstrates that a progressive decline in apparent viscosity occurs when blood flows through glass capillary tubes of diminishing radius, which was later designated as the "Fåhraeus-Lindqvist effect." Subsequent studies have shown that apparent viscosity continues to decline at diameters that correspond to the arteriolar segments of the systemic vascular tree, where the majority of the total peripheral resistance resides and is actively regulated in vivo. The Fåhraeus-Lindqvist effect thus reduces microvascular resistance, thereby maintaining local tissue perfusion at a relatively lower blood pressure. The paper by Fåhraeus and Lindqvist can be used as a platform for a plenary discussion of these concepts as well as of the relationships among hematocrit, vessel diameter, red blood cell deformability, and resistance to blood flow and how these factors may affect the work of the heart.

In France, sickle cell disease (SCD) is the most common rare disease and represents the most prevalent genetic disorder, with 19,800 to 32,400 patients diagnosed in 2016 and 1:714 newborns affected in 2019. SCD is caused by a single mutation in the β-globin gene, resulting in the production of abnormal hemoglobin (called HbS), chronic hemolytic anemia, and impaired red blood cell rheology. SCD patients face several severe acute and chronic complications, including stroke, acute chest syndrome (ACS), painful vaso-occlusive crisis (VOC), organ failure, and a high risk of infections. As patients' care pathway remains unclear in France, a roundtable advisory board meeting was organized in the country to provide insights into the management of SCD in alignment with clinical guidelines. The meeting brought together a panel of esteemed key opinion leaders (KOLs) in SCD management, encompassing both clinical practice and research. During the meeting, the KOLs discussed clinical practices and their alignment with French guidelines, identifying areas of concordance and discrepancy. They also addressed disparities in SCD clinical practices across regions and medical centers. The KOLs discussed the prophylactic and therapeutic options currently available for SCD patients in France, with a focus on transfusion therapies, especially automated red blood cell exchange (aRBCX). The results of this advisory board meeting provide a valuable platform for gathering expert perspectives on SCD management, clinical practices, guideline alignment, and the potential for contributions to guideline updates. [ABSTRACT FROM AUTHOR]

The Clinical Hemorheology & Microcirculation journal has established the A.L. Copley Best Paper Prize to recognize the best article published each year. The prize is named after Alfred Lewin Copley, the journal's founding editor. The winning paper for 2022 is titled "COVID-19 hemodynamic and thrombotic effect on the eye microcirculation after hospitalization: A quantitative case-control study" by Aristotle Koutsiaris and colleagues. The study investigates the impact of COVID-19 on the eye microcirculation of patients who received thromboprophylaxis after hospital discharge. The findings suggest that COVID-19 significantly reduces blood velocity and increases microthrombosis in the eye, potentially contributing to long COVID and indicating the presence of an unknown coagulation factor. [Extracted from the article]

The Chinese-Russian Workshop on Biophotonics and Biomedical Optics 2023 brought together scientists, engineers, and clinical researchers from Russia and China to discuss the application of optical science, photonics, and imaging technologies in biology and medicine. The workshop featured two plenary lectures and twenty invited presentations, and this special issue of the Journal of Innovative Optical Health Sciences includes selected papers from the workshop. The papers cover a range of topics, including optical imaging techniques, monitoring cell behavior, diffuse reflectance spectroscopy, photodynamic therapy, and neural networks for biomedical applications. The issue provides readers with the latest developments in biophotonics and biomedical optics. [Extracted from the article]

Seminars in Thrombosis and Hemostasis (STH) celebrates 50 years of publishing in 2024. To celebrate this landmark event, STH is republishing some archival material. This article represents the most highly cited paper ever published in STH. The original abstract follows.Blood is a two-phase suspension of formed elements (i.e., red blood cells [RBCs], white blood cells [WBCs], platelets) suspended in an aqueous solution of organic molecules, proteins, and salts called plasma. The apparent viscosity of blood depends on the existing shear forces (i.e., blood behaves as a non-Newtonian fluid) and is determined by hematocrit, plasma viscosity, RBC aggregation, and the mechanical properties of RBCs. RBCs are highly deformable, and this physical property significantly contributes to aiding blood flow both under bulk flow conditions and in the microcirculation. The tendency of RBCs to undergo reversible aggregation is an important determinant of apparent viscosity because the size of RBC aggregates is inversely proportional to the magnitude of shear forces; the aggregates are dispersed with increasing shear forces, then reform under low-flow or static conditions. RBC aggregation also affects the in vivo fluidity of blood, especially in the low-shear regions of the circulatory system. Blood rheology has been reported to be altered in various physiopathological processes: (1) Alterations of hematocrit significantly contribute to hemorheological variations in diseases and in certain extreme physiological conditions; (2) RBC deformability is sensitive to local and general homeostasis, with RBC deformability affected by alterations of the properties and associations of membrane skeletal proteins, the ratio of RBC membrane surface area to cell volume, cell morphology, and cytoplasmic viscosity. Such alterations may result from genetic disorders or may be induced by such factors as abnormal local tissue metabolism, oxidant stress, and activated leukocytes; and (3) RBC aggregation is mainly determined by plasma protein composition and surface properties of RBCs, with increased plasma concentrations of acute phase reactants in inflammatory disorders a common cause of increased RBC aggregation. In addition, RBC aggregation tendency can be modified by alterations of RBC surface properties because of RBC in vivo aging, oxygen-free radicals, or proteolytic enzymes. Impairment of blood fluidity may significantly affect tissue perfusion and result in functional deteriorations, especially if disease processes also disturb vascular properties., Competing Interests: None declared., (Thieme. All rights reserved.)

Diabetes mellitus (DM) is a complex, chronic metabolic disorder characterized by impaired regulation of blood glucose levels. Zinc (Zn) is an essential trace elements that plays a role in various physiological processes within the body, including those related to diabetes. The current study was investigated the effect of Zn supplementation on hemorheological parameters in a rat model of DM. After induction of DM, 32 male Wistar albino rats were divided into four groups: control, Zn, DM, and Zn+DM. Whole blood viscosity (WBV) was determined by using digital cone and plate viscometer and plasma viscosity (PV) was determined by a Coulter Harkness capillary viscometer. The rats in the DM Group showed a decrease in both Zn levels and body weight, as well as an increase in glucose levels when compared to the control group. Diabetic rats supplemented with Zn displayed lower blood glucose levels and higher concentrations of Zn compared to the DM Group. The higher PV and lower hematocrit level were measured in DM Group than control group and lower PV, higher hematocrit level were measured in Zn+DM group than DM Group. The WBV was measured at four different shear rates (57.6-115.2 - 172.8-230.4 s -1 ). A statistically significant increase was observed in the DM group compared to the control group. Additionally, a statistically significant decrease was observed in the Zn+DM Group compared to the DM Group at a shear rate of 230.4 s -1 . Erythrocyte rigidity index (T k ) and oxygen delivery index (ODI) were computed under conditions of high shear rate. The rats in the DM group exhibited a reduction in ODI and an elevation in T k in comparison to the control group. Conversely, the diabetic rats supplemented with Zn exhibited decreased T k and increased ODI compared to the DM Group. Zn supplementation seems to have a potential beneficial effect for protecting adverse affect of diabetes on hemorheogical parameters and for maintaining vascular health., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Devis Ozcelik reports financial support was provided by Istanbul University. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Dried blood spots (DBS) have proven to be a powerful sampling and storage method for newborn screening and many other applications. However, DBS methods have not yet been optimized for broad-spectrum targeted metabolomic analysis. In this study, we developed a robust, DBS-based, broad-spectrum, targeted metabolomic method that was able to measure over 400 metabolites from a 6.3 mm punch from standard Whatman 903TM filter paper cards. The effects of blood spot volumes, hematocrit, vacutainer chemistry, extraction methods, carryover, and comparability with plasma and fingerstick capillary blood samples were analyzed. The stability of over 400 metabolites stored under varying conditions over one year was also tested. No significant impacts of blood volume and hematocrit variations were observed when the spotted blood volume was over 60 µL and the hematocrit was between 31% and 50%. The median area under the curve (AUC) of metabolites in the DBS metabolome declined by 40% in the first 3 months and then did not decline further for at least 1 year. All originally detectable metabolites remained within detectable limits. The optimal storage conditions for metabolomic analysis were −80 °C with desiccants and without an O2 scavenger. The method was clinically validated for its potential utility in the diagnosis of the mitochondrial disease mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). Our method provides a convenient alternative to freezing, storing, and shipping liquid blood samples for comparative metabolomic studies. [ABSTRACT FROM AUTHOR]

Dried blood spot (DBS) sampling by finger-pricking has recently gained a lot of interest as an alternative sample collection method. The reduced invasiveness, requirement of lower sample volumes and suitability for long-term storage at room temperature make DBS ideal for use in home settings or low-resource environments. However, traditional protocols often suffer from biased analysis data due to variable and not exactly known blood volumes present in the samples. In this work, a novel device has been developed to split-off precisely metered volumes from a blood drop and load them on pre-cut filter paper. Hereto, hydrophobic burst valves (HBV) were developed to temporarily retain a fluid flow, configurable to burst at pressures within a range of 175–600 Pa. By combining HBVs with different burst pressures, a volume metering system was developed to allow parallel metering of multiple pre-defined sample volumes. The system was shown to be accurate and consistent for blood volumes between 5–15 μL and for hematocrit levels spanning the range of 25–70%. Finally, a point-of-care DBS sampling device was developed combining the self-powered microfluidic SIMPLE technology. To evaluate the system's practical applicability, a validation study in the context of therapeutic drug monitoring of biologicals was performed using adalimumab-spiked blood samples. Microfluidic DBS samples showed good performance compared to the traditional DBS method with improved recovery rates (86% over 62%). This innovative metering system, allowing for parallelization and integration with complex liquid manipulations, will greatly impact the field of robust sampling, sample preparation, storage and analysis at the point-of-care. [ABSTRACT FROM AUTHOR]

The immediate roof of Shanxi sedimentary bauxite is hard clay rock, which maintain stable difficultly in goaf. It is necessary to ensure the stability of the goaf during the mine production period. The relevant research objects did not involve soft rock mass such as bauxite and hard clay and did not pay attention to the weakening characteristics of load-bearing structures under the action of weathering and rheology. This paper provides theoretical support for the safety production of bauxite and similar mines. In order to study the relationship between the stability of the protective roof-pillar bearing structure and time, this paper uses elastic thin plates and rheological theory to build the physical model of the bauxite protective roof-pillar bearing structure, and gives the calculation formula of the stand-up time of the bearing structure. The influence of factors such as the thickness of the protective roof, the uniform surface force coefficient of pillar, the span of the goaf and the thickness of the overlying rock layer on the stand-up time of the bearing structure is analyzed. The relationship between the ultimate bearing capacity and stand-up time of the bearing structure is quantified. The results show that the bearing capacity of the bearing structure is affected by the mechanical properties of the rock mass and the structural parameters of the goaf. Under the condition that the influencing factors of the mechanical parameters of the rock mass remain unchanged, the stand-up time T, which represents the bearing capacity of the bearing structure, is positively correlated with the thickness of the protective roof, positively correlated with the uniform surface force coefficient of the pillar, negatively correlated with the span of the goaf and negatively correlated with the thickness of the overlying rock layer. The engineering example verifies the rationality of theoretical calculation and provides a new idea for mining safety. [ABSTRACT FROM AUTHOR]

Szechwan lovage rhizome (SLR, the rhizome of Ligusticum chuanxiong Hort., Chuanxiong in Chinese transliteration) is one Chinese materia medica (CMM) commonly used to activate blood circulation and remove blood stasis. SLR is applicable to most blood stasis syndromes. It has significant clinical efficacy in relation to human diseases of the cardiocerebrovascular system, nervous system, respiratory system, digestive system, urinary system, etc. Apart from China, SLR is also used in Singapore, Malaysia, the European Union, and the United States of America. However, the current chemical markers in pharmacopeia or monography for the quality assessment of SLR are not well characterized or specifically characterized, nor do they fully reflect the medicinal efficacy of SLR, resulting in the quality of SLR not being effectively controlled. CMM can only have medicinal efficacy when they are applied in vivo to an organism. The intensity of their pharmaceutical activities can more directly represent the quality of CMM. Therefore, the chemical constituents and pharmacological actions of SLR are reviewed in this paper. In order to demonstrate the medicinal efficacy of SLR in promoting blood circulation and removing blood stasis, bioassay methods are put forward to evaluate the pharmaceutical activities of SLR to improve hemorheology, hemodynamics, and vascular microcirculation, as well as its anti-platelet aggregation and anticoagulation properties. Through comprehensive analyses of these pharmaceutical properties, the quality and therapeutic value of SLR are ascertained. [ABSTRACT FROM AUTHOR]

In geotechnical engineering construction and underground ore mining, periodic cyclic fatigue loading is a major cause of rock mass instability and failure. With a constitutive model, the fatigue characteristics of rock masses can be studied effectively. Based on the similarities between rock mass rheology and cyclic fatigue loading, this paper applies rheological theory to study the fatigue characteristics of rock masses. Two constitutive models that describe different stages of nonlinear mechanical behaviour during the fatigue process were proposed, and a fatigue constitutive model that accurately describes the mechanical properties of rock during different fatigue stages was established after combining the two models. A sensitivity analysis showed that the model parameters EK, γ and δ can effectively reflect the deformation and damage evolution characteristics of the rock mass during the three fatigue stages. By comparing the laboratory splitting and three-point bending fatigue experiment results with the calculated model values, the rationality, reliability, and application scope of the model were verified. Moreover, based on the model parameter inversion results, the evolution mechanism of the rock mechanical properties during the different fatigue stages can be accurately understood. [ABSTRACT FROM AUTHOR]

For the optimization of ventricular assist devices (VADs), flow simulations are crucial. Typically, these simulations assume single-phase flow to represent blood flow. However, blood consists of plasma and blood cells, making it a multiphase flow. Cell migration in such flows leads to a heterogeneous cell distribution, significantly impacting flow dynamics, especially in narrow gaps of less than 300 μ m found in VADs. In these areas, cells migrate away from the walls, forming a cell-free layer, a phenomenon not usually considered in current VAD simulations. This paper addresses this gap by introducing a viscosity model that accounts for cell migration in microchannels under VAD-relevant conditions. The model is based on local particle distributions measured in a microchannels with a blood analog fluid. We developed a local viscosity distribution for flows with particles/cells and a cell-free layer, applicable to both blood and analog fluids, with particle volume fractions of up to 5%, gap heights of 150 μ m, and Reynolds numbers around 100. The model was validated by comparing simulation results with experimental data of blood and blood analog fluid flow on wall shear stresses and pressure losses, showing strong agreement. This model improves the accuracy of simulations by considering local viscosity changes rather than assuming a single-phase fluid. Future developments will extend the model to physiological volume fractions up to 40%. [ABSTRACT FROM AUTHOR]

Fatigue cracking has hitherto been a crucial constraint on the development of reclaimed asphalt pavements attributed to the performance of rejuvenated asphalt binder. Therefore, it is extremely significant to evaluate the fatigue performance of rejuvenated asphalt precisely and objectively and to improve the fatigue life of rejuvenated asphalt binders. With preceding research in our group, this paper investigated the fatigue properties of waste rubber/oil (WRO) rejuvenated asphalt and universal rejuvenated asphalt by dynamic shear rheometer test (DSR). The applicability of common fatigue life evaluation indexes and the response to internal and external influences on the fatigue performance of rejuvenated asphalt were analyzed. It is demonstrated that Np20 corresponding to the mutagenesis of phase angle is physically significant and independent of the parameters including rejuvenator type, loading mode and loading level, which was recommended as the evaluation index for fatigue life of rejuvenated asphalt in this paper. The fatigue performance of both WRO and universal rejuvenated asphalt is found to decrease with loading frequency and loading level, but the fatigue life of WRO rejuvenated asphalt is comparatively superior to the latter, particularly at high loading frequencies and levels. Influenced by waste tire crumb rubber (WTCR), increasing the proportion of WTCR can improve the fatigue life of rejuvenated asphalt. When compared to other rejuvenated asphalt, RWRO@55 rejuvenated asphalt shows better fatigue performance and its fatigue life rebounds at high loading frequency. Consequently, the recommended mastic–oil ratio is 5:5. However, when the rheological recoverability compensation is considered, the fatigue lifetime evaluation of rejuvenated asphalt will be changed significantly, and therefore the fatigue performance evaluation of rejuvenated asphalt should consider the influence of rheological recoverability to develop a comprehensive evaluation system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluation of a near-infrared set-up for the prediction of the hematocrit. • Successful validation with excellent accuracy and precision results. • Robustness experiments were performed to ensure the applicability in clinical practice. • Application on capillary DBS samples obtained via finger prick was included. Dried blood spot (DBS) microsampling has gained interest in different clinical fields, owing to its many advantages compared to conventional blood sampling. However, whilst being applied for decades for screening purposes, some challenges, such as the hematocrit (Hct) effect, hinder further widespread use of DBS for quantitative purposes in clinical practice. Amongst the approaches that were developed to cope with this issue, is the Hct prediction of DBS using near-infrared (NIR) spectroscopy. Using left-over EDTA-anticoagulated patient samples, the accuracy and precision, stability, and robustness were assessed. Furthermore, applicability of the method on capillary DBS was evaluated via finger prick samples. A maximal bias, respectively CV, of 0.012 L/L and 4.5% were obtained. The method was robust towards several aspects, including storage (except for storage at 60°C), measurement location, type of filter paper and spotted volume. Furthermore, the potential to predict the Hct of capillary DBS was demonstrated. A commercially available NIR set-up was extensively and successfully validated, allowing non-contact Hct prediction of DBS with excellent accuracy and precision. This allows to correct for the Hct-based bias observed in partial-punch DBS analysis and the set-up of blood-plasma conversion factors, increasing the application potential of patient-centric sampling. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effect of different environmental conditions on the aging properties of virgin asphalt binder and evaluate the magnitude of aging on asphalt binder under different environmental conditions. The effect of thermal, oxidative and ultraviolet aging on the rutting resistance, fatigue resistance and cracking resistance of virgin asphalt binder was characterised based on rheological parameters. The contribution rate of different environmental factors to the aging of asphalt binder was quantitatively analysed. Results showed that high temperature repaired cracks in the asphalt binder caused by ultraviolet aging. The single aging factor of heat, oxygen and light had little effect on the rheological properties of asphalt binder. High temperature and oxygen would accelerate the aging effect of the asphalt binder aging process. Thermal–oxidative–UV-coupled aging had a more pronounced effect on the aging of asphalt binder than thermal–oxidative aging. The fatigue resistance of asphalt binder is more sensitive to the response of aging. The contribution rates of thermal–UV aging, UV–oxidative aging and thermal–oxidative aging were all greater than the sum of the contribution rates of the two corresponding single factors. The aging of asphalt binder was mainly due to thermal–oxidative aging when the aging temperature exceeded 80°C. [ABSTRACT FROM AUTHOR]

In this paper, we study the blood flow through blood vessels of various radii (including the case of variable cross section as well as modeling the blood flow through venae and arteries). Two approaches are discussed in order to mimic the dependence of blood viscosity on red blood cells aggregation, which changes with the shear rate and position inside the vessel: Two microstructural parameters together with empirical constitutive equations as a characteristic of aggregation are proposed, namely the microinertia as well as the volume fraction of blood particles (erythrocytes, platelets and leukocytes). Consequently, the Navier–Stokes system of equations for an incompressible fluid is supplemented by a constitutive equation for the moment of inertia in one case and for the volume fraction in another. The problems are solved numerically by the finite volume method for vessels of various geometries in spatial description. A comparison with experimental data for a narrow capillary shows the efficiency of the proposed constitutive equations for describing blood flow. Also, velocity profiles are obtained on the basis of compiled empirical formula for various sections of a blood vessel of variable radius. In addition, the flow through vessels of the human circulatory system, such as the inferior vena cava and the carotid artery, are studied. [ABSTRACT FROM AUTHOR]

This paper investigated, for the first time, the feasibility of using peanut shell powder, a plant waste residue, as a modifier for asphalt, particularly its self-healing ability. Modified asphalt samples were prepared using varying particle size ranges and concentrations of peanut shell powder. Various tests, including fatigue–healing–fatigue tests, high- and low-temperature rheological property tests, penetration tests for conventional performance, and atomic force microscopy scans, were conducted to investigate the effects of peanut shell powder on the self-healing performance and other properties of asphalt. The results showed that the porous structure of peanut shell powder was able to absorb light components within the asphalt and release them under load, thus improving the self-healing and fatigue resistance properties of the modified asphalt. Experimental conditions such as temperature, healing time, and fatigue damage level also influenced the self-healing performance of asphalt. Additionally, peanut shell powder could increase the dynamic viscosity and high-temperature rheological property of modified asphalt while reducing its temperature susceptibility. However, it had a negative impact on the low-temperature ductility and creep rate, which could potentially lead to premature cracking of asphalt pavement in colder regions. Increasing the content of peanut shell powder and reducing its particle size within a certain range had positive effects. When the content of peanut shell powder was 4% and the particle size range was 80–100 mesh, the overall performance of modified asphalt was satisfactory. [ABSTRACT FROM AUTHOR]

The importance of the blood flow feature on the hemorrhage of the cerebral aneurysm is confirmed by surgeons and scientists. In this paper, the effects of blood hemodynamics on the growth and rupture of the Internal Carotid Intracranial (ICA) are fully investigated. This study tries to demonstrate the blood feature inside the ICA at different time stages. Besides, the effect of coiling on blood characteristics is extensively studied in this research. Computational Fluid dynamic (CFD) is used for the analysis of the blood hemodynamics on the wall shear stress and pressure distribution within the aneurysm. Obtained results indicate that reducing the coiling porosity from 0.89 to 0.79 declines maximum WSS by about 26% and 61% for HCT = 0. 3 5 and 0.45, respectively, at the peak systolic stage. Our findings show that decreasing the porosity (or increasing coiling fraction) would decrease the maximum OSI by more than 55% in high blood viscosity of HCT = 0. 4 5. [ABSTRACT FROM AUTHOR]

10.1063/5.0102669 5 A. Szulc, M. Mungan, and I. Regev, "Cooperative effects driving the multi-periodic dynamics of cyclically sheared amorphous solids", J. Chem. Phys. In the work of Szulc I et al. i ,[5] the authors consider an intriguing aspect of cyclically sheared amorphous solids, which is the presence of limit cycles that are multi-periodic. Due to this "melt memory", the crystallization temperature is higher than in the preceding cycle of crystallization. A polymer melt obtained by heating from its semicrystalline state undergoes crystallization at a higher crystallization temperature upon cooling than in the previous cycle of crystallization. [Extracted from the article]

This paper focuses on the dual quality of blood, Newtonian and non-Newtonian, in particular by exploring the energy curves. Careful investigation of the dual property of blood has been made by considering two different geometries to represent a stenosed arterial segment. We present a cautious assessment of non-Newtonian blood rheology impacts in arterial stream simulations by coupling the Newtonian and non-Newtonian models. The flow of energy through the two flow dimensions is meticulously investigated using velocity (kinetic energy), pressure, and wall shear stress (pressure energy). Besides, the proper implementation of an interface boundary condition (IBC) was emphasized to ensure consistency with the flow conditions downstream of a backward-facing step. The integration of the Newtonian and non-Newtonian models adjoins the novelty of the current research. The energy curves are obtained by implementing five different non-Newtonian models to designate a suitable non-Newtonian model for blood flow investigations. The combination of the non-Newtonian models enforced in this research is novel and particular attention is paid to the energy curves obtained. The conclusion was to elect the Carreau model as a suitable non-Newtonian rheological model for the blood flow study. This study was able to finalize the fact that the coupling of Newtonian and non-Newtonian models is necessary to obtain accurate results. For the sinusoidal waveform considered for the velocity, Carreau and the Power law models yield better results, eliminating the other non-Newtonian models from the list. With a better inlet condition imposed in the form of the Fourier series for pressure and velocity, the Carreau model yields the best results. [ABSTRACT FROM AUTHOR]

Research on hemorheology and blood flow behavior in non-uniform vessels is of extreme significance for diagnosis and treatment of many cardiovascular diseases. The aim of this study is to reveal the hemodynamics in stenotic vessels, and provide a reference for formulating a clinical operation plan. A set of rheological data of human blood at 37° is utilized in the paper to construct the fractional Maxwell constitutive equation of blood. Consequently, the continuity and momentum equations of a fractional Maxwell fluid passing through a stenosis artery in a two-dimensional cylindrical coordinate system are established. With the help of the vorticity and stream function, the finite difference method combined with the fractional order derivative L1 algorithm is applied to acquire the numerical solutions of the velocity, wall shear stress and intravascular pressure gradient, and the validity of the algorithm is verified. Furthermore, the effects of the stenosis degree, stenosis shoulder length, various Reynolds numbers and fractional parameter α on the blood flow characteristics in stenosis are analyzed. [ABSTRACT FROM AUTHOR]

This paper numerically investigates the impact of fluid rheology on the behaviors of a spherical capsule through a microchannel constriction. Different flow scenarios are considered: a Newtonian capsule in a viscoelastic matrix, a Newtonian capsule in a Newtonian matrix, and a viscoelastic capsule in a Newtonian matrix. The results demonstrate that the capsule's lengths undergo oscillations during the passage through the constriction, with three stages of evolution. When approaching the constriction, the capsule respectively experiences increase and decrease in its length and height. While within or exiting the constriction, the length of the capsule continuously decreases, and the height generally increases. As the capsule moves away from the constriction, the capsule relaxes to different profiles in different flows. Detailed analysis on the effects of the fluid viscoelasticity on the capsule's lengths in different stages is provided. In addition, the behaviors of a red blood cell passing through a microchannel constriction are also examined. This study sheds light on the complex behaviors of a spherical capsule and red blood cell in microchannel constriction, emphasizing the significant influence of fluid rheology on their deformation and shape changes. [ABSTRACT FROM AUTHOR]

Specific aspects of semi-solid dosage forms for topical application include the nature of the barrier to be overcome, aspects of susceptibility to physical and chemical instability, and a greater influence of sensory perception. Advances in understanding the driving forces of skin penetration as well as the design principles and inner structure of formulations, provide a good basis for the more rational design of such dosage forms, which still often follow more traditional design approaches. This review analyses the opportunities and constraints of rational formulation design approaches in the industrial development of new topical drugs. As the selection of drug candidates with favorable physicochemical properties increases the speed and probability of success, models for drug selection based on theoretical and experimental approaches are discussed. This paper reviews how progress in the scientific understanding of mechanisms and vehicle-influence of skin penetration can be used for rational formulation design. The characterization of semi-solid formulations is discussed with a special focus on modern rheological approaches and analytical methods for investigating and optimizing the chemical stability of active ingredients in consideration of applicable guidelines. In conclusion, the combination of a good understanding of scientific principles combined with early consideration of regulatory requirements for product quality are enablers for the successful development of innovative and robust semi-solid formulations for topical application. [ABSTRACT FROM AUTHOR]

Blood viscosity is the defining health indicator for hyperviscosity syndrome patients. This paper introduces an alternative approach for the real-time monitoring of blood viscosity by employing a surface-horizontal surface acoustic wave (SH-SAW) device at room temperature. A novel bi-layer waveguide is constructed on top of the SAW device. This device enables the SAW sensing of liquid droplets utilizing a bi-layer waveguide, consisting of a zinc oxide (ZnO) enhancement layer and Parlyene C, that facilitates the promotion of the surface horizontal mode. The ZnO piezoelectric thin-film layer enhanced the local particle displacement and dielectric coupling while the Parylene C layer constrained the wave mode at the interface of the piezoelectric material and polymer material. The device was tested with a liquid drop on the SAW delay-line path. Both experimental and finite element analysis results demonstrated the benefits of the bi-layer waveguide. The simulation results confirmed that the displacement field of local particles increased 9 times from 1.261 nm to 11.353 nm with the Parylene C/ZnO bi-layer waveguide structure. The device demonstrated a sensitivity of 3.57 ± 0.3125 kHz shift per centipoise enabling the potential for high precision blood viscosity monitoring. [ABSTRACT FROM AUTHOR]

34442536 17 Carotenuto F., Teodori L., Maccari A.M., Delbono L., Orlando G., Di Nardo P. Turning regenerative technologies into treatment to repair myocardial injuries. The ability to control and modify the surface topography of materials at the nanoscale, which produces features with a comparable size to that of biological entities, so as to effectively probe and influence processes at both the cellular and the molecular level, has facilitated incredible possibilities in the fields of biomedicine, biosensing, and diagnostics. The paper by Carotenuto et al. [[13]] presents an important example of such therapy-oriented systems, i.e., micro/nanostructured scaffold structures obtained through the careful optimization of the biomaterial micro/nano architecture, which can influence cellular behavior and guide cells towards a specific soft or hard tissue organization, thus representing a crucial mimicking strategy for successful regenerative therapy (see also [[14]]). [Extracted from the article]

The decrease in apparent relative viscosity that occurs when blood is made to flow through a tube whose diameter is less than about 0.3 mm is a well-known and documented phenomenon in physiology, known as the Fåhræus-Lindqvist effect. However, since the historical work of Fåhræus and Lindqvist (Amer. J. Physiol. 96(3): pp. 562–568, 1931), the underlying physical mechanism has remained enigmatic. A widely accepted qualitative explanation was provided by Haynes (Amer. J. Physiol. 198, pp. 1193–1200, 1960) according to which blood flows in microvessels with a core-annulus structure, where the erythrocytes concentrate within a central core surrounded by a plasma layer. Although sustained by observations, this conjecture lacks a rigorous deduction from the basic principles of continuum dynamics. Moreover, relations aimed to reproduce the blood apparent relative viscosity, extensively used in micro-circulation, are all empirical and not derived from the analysis of the fluid mechanical phenomena involved. In this paper, we apply the recent results illustrated in Guadagni and Farina (Int. J. Nonlinear Mech. 126, p. 103587, 2020), with the purpose of showing that Haynes' conjecture, slightly corrected to make it more realistic, can be proved and can be used to reach a sound explanation of the Fåhræus-Lindqvist effect based on continuum mechanics. We propose a theoretical model for the blood apparent relative viscosity which is validated by matching not only the original experimental data reported by Fåhræus and Lindqvist (Amer. J. Physiol. 96(3), pp. 562–568, 1931), but also those provided by several subsequent authors. [ABSTRACT FROM AUTHOR]

This paper calculates for liquid mixtures of high and low molecular weight components, how many solute molecules flow on the average conjointly. The application of the approach to solutions of poly(dimethyl siloxane) in its pentamer, to suspensions of gibbsite (Al(OH)3) in dimethyl sulfoxide, and to human blood testifies that the approach is applicable without restrictions regarding the chemical nature of the high molecular weight compound. The shear thinning of the systems under investigation can be understood in terms of a reduction of the shear-overlap parameter Σ, where the generalized intrinsic viscosity {η} constitutes the central property governing the composition and shear rate dependence of the viscosities. Furthermore, the present analysis demonstrates that intrinsic viscosities can be determined for all solutes and that they decrease with rising shear rates according to a Boltzmann sigmoid for the systems DMS5/PDMS and blood. The comparison of the hydrodynamic specific volumes of the solutes (i.e., of [η]) with the corresponding specific volumes in the pure state leads to the conclusion that solutes that cannot interpenetrate carry a considerable amount of solvent piggyback with them when flowing. In addition to the pure description of the observations, the approach was able to point to new phenomena, e.g., the solidification of the gibbsite suspensions beyond a characteristic solute concentration, which shifts to higher values with increasing shear rates. Because of its general nature, the present approach should become helpful, above all in the areas of technology (reactions in flowing systems) and health (rheology of blood). [ABSTRACT FROM AUTHOR]

Abstract —This work presents the results of GPS observations (2003–2020) carried out in PrimorskyKrai (aka the Primorie) and Khabarovsk Krai in southeastern Russia. The objectives of our study were to obtain displacement velocities, to test the relation of current velocities with seismicity, with the specific features of the geological structure of the Primorie, and to study the rheological parameters of the crust and asthenosphere at the continental margin. This paper analyzes the results of measurements made in the Primorie at the Central Sikhote-Alin fault. The study includes the effects of the Tohoku-Oki earthquake in Japan with magnitude М = 9 which occurred on March 11, 2011. The zone of coseismic and postseismic displacements extends to a distance of over 1000 km from the epicenter. The postseismic decay of the long-term horizontal and vertical displacements allow us to estimate the relaxation time for the elastic-viscous model. With the decay times of 4 to 8 years, the viscosity of the lower layer in the two-layer rheological model is estimated at 8 × 1018–3 × 1019 Pa s. Using the bending model of the Earth's surface and the bottom of the Sea of Japan, we estimated the thickness of the elastic upper part of the Earth's crust in the continent–ocean contact zone at 20–25 km. [ABSTRACT FROM AUTHOR]

In this paper, we suggest an iterative method for solving nonlinear equations that can be used in the physical sciences. This response is broken down into three parts. Our methodology is inspired by both the standard Taylor's method and an earlier Halley's method. Three evaluations of the given function and two evaluations of its first derivative are all that are needed for each iteration with this method. Because of this, the unique methodology can complete its goal far more quickly than many of the other methods currently in use. We looked at several additional practical research models, including population growth, blood rheology, and neurophysiology. Polynomiographs can be used to show the convergence zones of certain polynomials with complex values. Polynomiographs are produced as a byproduct, and these end up having an appealing look and being artistically engaging. The twisting of polynomiographs is symmetric when the parameters are all real and asymmetric when some of the parameters are imaginary. [ABSTRACT FROM AUTHOR]

The article presents the discussion on complex relationship between blood fluidity and cardiovascular function, emphasizing the critical role of hemodynamics and blood rheology in health and disease. Topics include key concepts in rheology, the clinical impact of hemorheology on cardiovascular health; and the importance of understanding shear-dependent blood viscosity in vascular resistance.

In the underground activity domain, most problems related to mining pressure and mining stability need to be solved by taking into account the time behavior of rocks through an approach of the interaction amidst the rock massif, support system, time through the elastic, viscous and plastic models, namely a rheological approach. In order to choose a rational support system, one needs to know the sustainment solicitation at different time intervals. The change in the sustainment in time is emphasized only in the analytical research in which the massif is studied and characterized in terms of the rheological behavior. The gradient method applied in this regard is based on the evolution of the final deformations at a given time, compared to their previous evolution. The paper is structured into two parts, the experimental and interpretation of the experimental data, showing the author's methodology to assess the rheological behavior of analyzed andesite, the result of the theoretical and experimental research being carried out on the analyzed rock types. Based on the deformation and the time curve of the horizontal mining work contour, the mathematical function was established, which expresses the law of sought deformation. At the same time, the rheological model capable of describing the behavior under a load and under extremely adverse conditions is proposed. [ABSTRACT FROM AUTHOR]

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Elucidating the complex processes that determine the ability of the human body to adapt to specific intense training programs is critical to improving athletic performance in elite athletes. The present work aims to describe the main hemorheological changes as a result of physical exercises of different intensity, frequency, duration and modes of loading. Sport and physical exertion induce a hemorheological response of different nature and degree, structured in the present paper as follows: erythrocyte aggregation; change in the concentration of basic plasma components; changes in blood flow; changes in blood volume; changes in the endothelial cells of the vascular walls; changes in blood pressure; changes resulting from tissue hypoxia; interacting, different in nature hemorheological consequences. The studied and described original models of hemorheological response can contribute to a more successful adaptation of the training programs—In order to improve the health status of the participants and to optimize the sports form of the elite athletes. Physical loads of different frequencies, intensities and durations induce a different hemorheological response in athletes. The effect of "regular, moderate and properly dosed physical activity" during training is also strictly individual. This fact suggests approaching the training regime of each elite athlete personally, practicing specific to his preparation, well-chosen, balanced physical exercises. This will help to achieve the so-called state of hemorheological fitness. Extensive future research is needed to elucidate the cellular, tissue and molecular mechanism of hemorheological changes in blood, blood cells, and blood plasma. It is essential to study the vascular characteristics and biomechanical properties of blood under physical loads with different regimes and variable parameters, taking into account the individual, professional, biological and mechanical profile of each athlete. [ABSTRACT FROM AUTHOR]

In this paper, an optimal higher-order iterative technique to approximate the multiple roots of a nonlinear equation has been presented. The proposed technique has special properties: a two-point method that does not involve any derivatives, has an optimal convergence of fourth-order, is cost-effective, is more stable, and has better numerical results. In addition to this, we adopt the weight function approach at both substeps (which provide us with a more general form of two-point methods). Firstly, the convergence order is studied for multiplicity m = 2 , 3 by Taylor's series expansion and then general convergence for m ≥ 4 is proved. We have demonstrated the applicability of our methods to six numerical problems. Out of them: the first one is the well-known Van der Waals ideal gas problem, the second one is used to study the blood rheology model, the third one is chosen from the linear algebra (namely, eigenvalue), and the remaining three are academic problems. We concluded on the basis of obtained CPU timing, computational order of convergence, and absolute errors between two consecutive iterations for which our methods illustrate better results as compared to earlier studies. [ABSTRACT FROM AUTHOR]

This article, titled "Roles of Erythrocytes in Human Health and Disease 2.0," explores the various factors that influence red blood cell (RBC) biology, including COVID-19 infection, sickle cell disease, preeclampsia, reactive oxygen species, glucose control, favism, and the tumor microenvironment. The collection of 11 papers in this special issue aims to understand the underlying mechanisms and consequences of these influences on RBC function and physiology through a multidisciplinary approach. The studies included in this issue investigate topics such as the impact of COVID-19 on RBC aggregation, the biophysical profiling of sickle cell disease, and the influence of preeclampsia on neonatal erythrocyte characteristics. Overall, this special issue advances our understanding of the complex influences on RBC biology and their implications for human health and disease management. [Extracted from the article]

Poly(N-acryloylglycinamide) (PNAGA) exhibits an upper critical solution temperature (UCST) behaviour in aqueous solutions, and unlike typical polymers, dissolution is more sensitive to temperature and solutions may exhibit an extraordinary rheological behavior. Homopolymers of NAGA with different molecular weights were synthesized, the rheological behavior of the polymer solutions was investigated, and the scaling relationships of the dilute solutions of polymers were analyzed. The results indicated that PNAGA is a thermoviscosifying polymer in aqueous solutions. Besides, the thermoviscosifying behaviour was intense above 50 °C, as well as at lower concentrations, and the viscosity rising up to 27.61 times at concentration of 0.1%. The lower molecular weight polymers prepared showed more thermoviscosification. The polymer solutions are thermoviscosified over the range of tested shear rates, exhibiting increased shear resistance. Light scattering tests showed that the molecular size increased with increasing temperature at the same concentration, combined with the scale relationship that the solution contact concentration decreased with increasing temperature, indicating polymer coil expansion with increasing temperature. [ABSTRACT FROM AUTHOR]