Rheological properties of the whole blood of rheumatological patients

Using the method of nonstationary rheometry, the changes occurring in the rheological properties of the blood of rheumatological patients in plasmapheresis in the range of rates of shear of 1–10 sec⁻¹ at a temperature of 37°C were studied. These studies were paralleled by measurements of the hematocrit index to correct the viscosity of the blood. A statistically reliable mathematical dependence of the change in the rheological properties of blood in plasmapheresis has been constructed. The role of the rheological factor of blood as a possible additional diagnostic parameter in plasmapheresis has been evaluated. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 792–796, July–August, 2000.     

Rheological changes in the blood and plasma of patients with myocardial ischemia and diabetes mellitus and dysfunction of their endothelium

The rheological properties of the whole blood and plasma of patients with myocardial ischemia and diabetes mellitus and of donors have been investigated using a Couette rotational viscosimeter at a temperature of 25°C in the range of rates of shear of 0.5–60 sec⁻¹. The rheological analysis was performed with the use of the Quemada relation. The functional state of the endothelium and some biochemical indices of the blood of these patients were investigated. It is shown that in patients with myocardial ischemia and diabetes mellitus, accompanied by dyslipemia and endocrine disturbances, rheological derangements and endothelial dysfunction develop. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 96–101, January–February, 2006.     

Rheology and microstructure of MDI–PEG reactive prepolymer-modified bitumen

This paper deals with the use of a new bitumen modifier, a reactive prepolymer, based on the reaction of 4,4^′-diphenylmethane diisocyanate (MDI) and a low molecular weight polyethylene glycol (PEG). The rheological and thermal behaviours of modified bitumen containing a low MDI–PEG concentration, as well as its morphology, have been studied. A relatively low amount of MDI–PEG (0.5 to 1.5% wt.) yields a significant improvement in the modified bitumen rheological properties, mainly in the high in-service temperature region. In this range of temperature, the rheological properties are clearly affected by curing time at room temperature. These results indicate that chemical changes, due to the reaction of MDI isocyanate groups with the most polar groups (–OH; –NH) of asphaltenes and resins, are produced. Thus, new chemical structures, non-visible by optical microscopy, slowly develop in MDI–PEG modified bitumen when samples are cured at room temperature.     

The hemorheological basis of transfusion therapy in the case of extrauterine pregnancy

The authors have studied 122 medical histories of extrauterine pregnancies from archives and directly followed up 122 patients who underwent emergency surgery for extrauterine pregnancy. Particular disturbances of rheological properties of blood in patients with ectopic pregnancy are revealed. The authors prove the necessity of rheologically active infusion-transfusion therapy, which normalizes rheological properties of blood, its acidic and basic conditions, and protein composition both during the operation and in the postoperational period. The following solutions were used: acesol, Haemodesum, rheopolyglucine, rheoglumane, gelatinol, 10% albumin solution, and fresh frozen plasma. Minsk State Medical Institute, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69 No. 3, pp. 456–459, May–June, 1996.     

Influence of the temperature and oversouring of blood on its hemorheological properties

The influence of the change in the temperature and the acidity of blood on its hemorheological properties has been analyzed. It is shown that, at temperatures lower than 45°C, the temperature dependence of the apparent viscosity of blood at a rate of shear ranging from 0.3 to 50 sec⁻¹ is adequately defined by the Arrhenius model with a viscous-flow activation energy of 13–17 kJ/mole. In the range of pH 6.3–7.6, the oversouring of blood mainly influences the critical shear stress, and the Caisson viscosity depends only weakly on the acid-base equilibrium. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 180–185, September–October, 2005.     

Identification of the nonlinear viscous properties of fluids by the vibrational method

Effects occurring in an oscillatory viscosimeter upon its filling with nonlinear viscous fluids whose rheological properties are described by the Ostwald-Weyl model have been revealed. The possibilities of the vibrational method for identification of the rheological belonging of media to nonlinear viscous ones with a power rheological law and of their nonlinear properties in the regime of free damped and forced vibrations have been discussed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 70–77, September–October, 2005.     

Investigation of radiation effects caused by the interaction of β<Superscript>−</Superscript>-radiation with polyvinyl chloride

The dissipation of the energy of β⁻-radiation in polyvinyl chloride has been analyzed. The change in the properties of polyvinyl chloride under the action of β⁻-particles with an energy of 2.32 MeV has been characterized using the potentials of intermolecular and intramolecular interactions and the Bohr potential. The interrelation between certain micro-and macroproperties of polyvinyl chloride was determined and methods of their control with the use of β⁻-radiation were developed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 186–192, January–February, 2007.     

Dosimetric properties of tungsten-containing complexes of carboxymethyl cellulose

A study is made of the change in the optical properties of polymer compositions based on W-containing complexes of highly substituted carboxymethyl cellulose under the action of ionizing radiation (α-particles,⁶⁰Co γ-rays). It is shown that film layers based on the complexes mentioned can be used as radiochromic materials for α-radiation dosimetry in the dose range of 4·10²–5.1·10⁵ Gy. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 443–446, March–April, 2000.     

Investigation and calculation of the stressed-strained state and compaction of viscoelastic disperse media as a result of relaxation processes

A theoretical study of the change in the stressed-strained state and compaction, under loading, of viscoelastic disperse media (including soils) with rheological properties varying with deformable-layer depth has been made. The processes of creep and relaxation of such media have been investigated. Calculations from the formulas derived for compactible soils have been carried out based on experimental data on the rheological properties of soils. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 78–86, September–October, 2005.     

Effects of introducing silica particles on the rheological properties and crystallization behavior of poly(ethylene terephthalate)

Poly(ethylene terephthalate) (PET)/silica composites were prepared by melt compounding, and their rheological properties and isothermal crystallization were discussed. Introduction of silica particles (0.5–2 wt.%) increased the storage modulus (G′) and decreased loss tangent (tanδ). However, the effect of the particles on rheological properties became negligible at a high frequency more than ca. 70 rad/s. In the Cole–Cole plot, the PET/silica composites showed little deviation from the master curve regardless of the presence of silica particles. The particles increased the relaxation time of PET at particularly low frequency. The isothermal crystallization kinetics of PET/silica was examined using a differential scanning calorimeter (DSC). The half-time of crystallization was decreased with increasing the silica content. The incorporation of silica particles decreased the equilibrium melting temperature by ca. 5.5 °C. In addition, the composites exhibited higher average value of Avrami exponent (2.7–2.9) in comparison with that of pure PET (2.2).     

Thermal destruction of erythrocyte spectrin: Rheology,deformability, and stability with respect to detergents

By means of blood heating in the region of the thermal denaturation transition of spectrin (50°C) the relationship between the stability of erythrocytes with respect to detergents and their deformability and rheological parameters of blood was studied. Academic Scientific Complex “A. V. Luikov Institute of Heat and Mass Transfer, Academy of Sciences of Belarus,” Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 3, pp. 360–363, May–June, 1996.     

Processing conditions, morphology and properties of a polycarbonate + a thermotropic polymer liquid crystal blend

We have investigated phase structure – properties relationships of polycarbonate (PC) + a polymer liquid crystal (PLC) blends processed in a twin-screw extruder at several conditions. The PLC is PET/0.82 PHB – a copolyester of poly(ethylene terephtalate) and p -hydroxybenzoic acid. For comparison the blend was additionally extruded in a wide range of shear rates in a capillary rheometer at two different spinning rates and compression-molded. The blend processed in the rheometer exhibits lower values of modulus and tensile strength than the blend extruded due to destruction of the initial orientation and dispersion level gained during extrusion. The orientation of PLC-rich islands increases up to the shear rate of 50–100 s^–1, whereas deformation at higher shear rates exhibits a droplet–breakup phenomenon, confirmed by SEM micrographs. The rheological measurements (oscillation mode) evidence a high shear thinning of the PLC. By contrast, the influence of the deformation rate on the viscosity for PC and the blend is negligible, suggesting also a low interaction level in the interfacial area. This conclusion was confirmed by dynamic mechanical measurements. As expected, our experiments prove that structure and properties of the blend are affected by processing (shear and elongation) conditions. Increasing shear rate leads to elongation of dispersed domains but exceeding critical values can lead to droplet breakup and destruction of created structure. The unique morphology created during extrusion can be destroyed during additional processing (in rheometer). Formation of fibrils is also dependent on additional treatment – spinning speed. Optimized spinning speed can lead to 50% increase in stiffness of the blend. Electronic Publication     

Mechanisms of Viscoelastic Soil Deformation Under Cylinder Rolling

The mechanisms of deformation by a circular rolling cylinder of a viscoelastic soil with depth-varying physical properties have been investigated. A method for calculating the indices characterizing the rheological properties, the stressed-strained state, and the density of the soil upon the first passage over the soil and upon many passages of a cylinder over one track is proposed. A quantitative assessment of the influence of the basic factors on the change in the rheological properties of the soil and their tending to elastic ones as a result of a number of cylinder passages over one track has been made. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 3, pp. 153–162, May–June, 2005.     

Influence of binary additives of compatibilizers on the micro-and macrorheological properties of melts of polypropylene-copolyamide mixtures

We have investigated the influence of binary additives of compatibilizers copolymer of ethylene with vinyl acetate/siloxane liquid on the rheological properties of melts and the processes of structure formation in polypropylene-copolyamide mixtures. It has been shown that there exists an optimal ratio of compatibilizers at which the maximum influence of additives on the process of specific fiber formation shows up. The mechanism of their action is connected with an increase in the length of the interphase layer, a decrease in the surface tension, and an increase in the lifetime of the liquid jet. The use of compatibilizers influences the viscosity of melts only slightly, and the capability of four-component compositions to be processed markedly increases. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 4, pp. 737–743, July–August, 2008.     

Contribution à l'étude de la rhéologie du béton frais

Summary The essential object of this study is to contribute to liberate the rheological study of fresh concrete from the present-day empiricism. For this an apparatus has been developed to determine the flow curve of the material and thus obtain its rheological equation of state. Changes in rheological behaviour have thus been shown relative to the dynamic state of the material (vibrated or not), the solid concentration and the shape of the aggregate. This study finally deals with the influence of the solid concentration, the grain size, the shape and nature of the aggregate on the viscosity of fresh mortars vibrated or at rest.

---

Voir la première partie dans Matériaux et Constructions N^o 29 (sept.–oct. 1972), pp. 275–295.     

Simulation of the rheological behavior of enterosorbents in the gastroenteric tract <Emphasis Type="Italic">in vitro</Emphasis>

The influence of the temperature, pH, and a polymer on the properties and stability of activated coal suspensions serving as nonspecific enterosorbents has been considered. The rheological properties of the small-intestine chyme in vitro and the influence of an enterosorbent on them have been investigated. The advantages of using a water-soluble cellulose polyelectrolyte, as compared to an amylum, for preparation of tableted or grained activated coal are demonstrated. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 147–151, September–October, 2005.     

Rheological behavior of oils in a magnetic field

The influence of magnetic treatment parameters on the rheological properties of oils has been investigated. It has been noted that the strongest effect on these properties is produced by the regime of magnetic treatment — steady-state or flowing, the volume rate of oil flow, and the induction value of the magnetoactivator magnetic field. The optimal regimes of magnetic treatment have been determined. It has been shown that treatment of oil with a magnetic field promotes a decrease in the solidification temperature and the amount of asphalt-resin deposits. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 102–109, January–February, 2006.     

Field ion microscope examination of the action of an intense ion flux from a laser plasma on tungsten

Results are presented of field ion microscope examinations of the structure of tungsten samples exposed to the action of a high-intensity ion flux (∼10²² ions/cm²·s) from a lead laser plasma. It was observed that the surface layer becomes amorphized and the defect spectrum was established. The limiting mechanical properties of irradiated tips were determined. Promising directions for further research are indicated. Pis’ma Zh. Tekh. Fiz. 24, 52–57 (November 26, 1998)     

About temperature dependence of the rheological properties of human blood at low shear rates

Measurements of the human blood flow curve as a function of temperature are reported. The blood was sampled from healthy donors. The measurements were made at the shear rates from 0.2 to 5.0 sec⁻¹ in the temperature range 30–45°C. The blood flow curve was investigated by the nonstationary measurement method using a specially designed viscosimeter. An experimental study of the human blood flow curve at low shear rates allowed investigation of the temperature dependence of the Casson’s model parameters describing it. It is shown that these parameters have a complicated temperature dependence that exhibits a specific feature at 42°C. Academic Scientific Complex “A. V. Luikov Heat and Mass Transfer Institute, Academy of Sciences of Belarus,” Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 3, pp. 386–389, May–June, 1996.     

Size dependent optical characteristics of chemically deposited nanostructured ZnS thin films

ZnS thin films of different thicknesses were prepared by chemical bath deposition using thiourea and zinc acetate as S²⁻ and Zn²⁺ source. The effect of film thickness on the optical and structural properties was studied. The optical absorption studies in the wavelength range 250–750 nm show that band gap energy of ZnS increases from 3·68–4·10 eV as thickness varied from 332–76 nm. The structural estimation shows variation in grain size from 6·9–17·8 nm with thickness. The thermoemf measurement indicates that films prepared by this method are of n-type.