Showing papers on "Viscometer published in 2023"

A droplet-based micropillar-enhanced acoustic wave (μPAW) device for viscosity measurement

Abstract: Viscosity monitoring has recently received significant attention in various fields such as pharmacy, oil industry, food industry, and medical diagnostics. Given that the commercially available viscometers usually require a large sample volume to conduct accurate measurement, there is an urgent need to develop a viscometer that can consume the least sample while maintaining high accuracy. Despite of being simple, rapid, and cost-effective, quartz crystal microbalance (QCM) based viscometers are low in sensitivity and not able to measure viscosity directly. This work focuses on the development of a novel micropillar-enhanced QCM viscosity measurement device which relies on the coupled vibration between micropillars and quartz substrate (QCM-P) to achieve an ultra-sensitive viscosity measurement of a sample droplet. A hybrid model by integrating an equivalent circuit and numerical simulation approach was established to understand the working principle of the QCM-P device and evaluate the viscosity value. The experimental results and analysis demonstrate that the micropillar-enhanced acoustic wave (μPAW) devices such as QCM-P viscometer is a promising device for droplet-based viscosity measurement.

About Complex Oil Flow Curve Form in Anomaly Viscosity Low Temperatures and Shear Rates Conditions

Abstract: This paper presents results of studies of the problem to describe the nature of oil flow at low temperatures and shear velocities for prediction of flow fluidity and determination of the parameters of a cold start of an oil pipeline after an extended downtime. Analytical and experimental studies have been carried out, which include a review of rheological test data from earlier studies available in the literature and an analysis of empirical relation obtained with the rotational viscometry method. More specifically, the existence of a zone of viscosity anomaly for low-paraffin and heavy oils has been proved on the basis of laboratory test data of model mixtures of commercial crude oils and their weighted samples. The necessity has been substantiated to create more adaptive rheological models which fit the total curve of oil flow, including the zone of viscosity anomaly in the transient state of cold start, this zone manifesting itself when reaching a certain temperature, even for low-paraffin oils. Based on the results of this work, the most advance multi-factor rheological models have been identified for description of the total shape of the rheological curve in a wide range of temperatures and velocities.

A Research on Rheological Behavior of Aqueous Solutions of Pomegranate Peel Powder

Abstract: Determining the viscosity of pomegranate peel powder (PPP) can aid in product development, process optimization, quality control, ingredient interactions, and scientific research related to pomegranate peel-based products or formulations. Therefore, in this study, the rheological behavior of dried and ground pomegranate peel has been investigated. The apparent viscosities of pomegranate peel solutions prepared with distilled water are measured by a rotational viscometer. The viscosity of the pomegranate peel solution at each concentration is measured at shear rates varying between 2.64 s-1 and 22 s-1 at constant temperature (25 °C). When the effect of concentration on apparent viscosity has been examined, it is observed that the viscosity rises with increasing concentration at a constant shear rate. Among the rheological models studied, Power model provides a good fit for the experimental viscosity data of aqueous solutions of pomegranate peel powder at different concentrations. The consistency coefficient and the flow behavior index are calculated using the power law model and the solutions have been found to exhibit pseudoplastic behavior.

Possibilities of Physical-Chemical Sensors’ Use for Optimizing the Processing of Metallurgical Melting Based on Computer Systems

Abstract: This article presents aspects regarding the possibilities of optimizing the quality of the elaboration of metallurgical melts by determining their physical-chemical properties. Thus, the article analyzes and presents methods for determining the viscosity and electrical conductivity related to metallurgical melts. Among the viscosity determination methods, two methods are presented, namely: the rotary viscometer method and the electro-vibratory viscometer method. Determining the electrical conductivity of a metallurgical melt is also of particular importance for ensuring the quality of the elaboration and refining of the melt. The article also presents the possibilities of using and implementing computer systems that ensure the accuracy of determining the physical-chemical properties of metallurgical melts, as well as examples of the use of physical-chemical sensors and specific computer systems for determining the analyzed parameters. The specific electrical conductivity measurements of oxide melts are performed by direct methods (by contact), with Ohm’s law as a starting point. Thus, the article presents the voltmeter-ammeter method and the point method (or the zero method). The novelty of this article is the description and the use of specific methods and sensors for certain determinations (viscosity and electrical conductivity) for metallurgical melts. The motivation here is the presentation of the authors’ research in the addressed field. The article presents an original contribution of the adaptation and use of some methods for determining some physico-chemical parameters, including specific sensors, in the field of the elaboration of metal alloys, with the aim of optimizing their quality.

Assessing rheometry for measuring the viscosity-average degree of polymerisation of cellulose in paper degradation studies

Abstract: Abstract In paper degradation studies, the viscosity-average degree of polymerisation (DP v ) is often used as a key indicator of the extent of degradation of cellulosic paper. DP v can be deduced from the viscosity of dilute paper solutions, as typically measured through glass capillary viscometry. The current study proposes an efficient, alternative method to evaluate DP v of cellulosic paper, which is based on rotational rheometry. The proposed methodology relies on the application of a shear flow in a thin film of cellulose solution to measure its dynamic viscosity, from which DP v can be subsequently derived in a straightforward fashion. Rheometry allows to measure the viscosity for a range of shear rates, which results in multiple DP v evaluations per sample, and thus in statistically representative data from an individual test. Further, rheometry typically requires considerably less paper mass per test than glass capillary viscometry, which makes the method attractive for paper degradation studies with limited sample availability. Also, rheometry measurements are less work-intensive than glass capillary viscometry measurements. The rheometry method has been applied to 4 hygrothermally aged cellulose paper samples and the unaged counterpart. The measurement results regarding the age-dependency of DP v and the number of cellulose chain scissions are compared to those obtained by glass capillary viscometry, showing a very good agreement. At a longer ageing time, both experimental methods reveal a non-linear decrease in time of DP v , and a non-linear increase in time of the number of cellulose chain scissions, which indicate that the cellulose ageing process is realistically captured. The agreement in measurement results further demonstrates that rheometry is an easy-to-use, accurate and efficient alternative for DP v measurements by glass capillary viscometry.

Effect of Al2O3 and TiO2 on Viscosity, Surface Tension, and Density of Blast Furnace Slag with CaO/SiO2 = 1.13

Abstract: The influence of Al2O3 in the range of 10–20 mass% and TiO2 in the range of 0.55–5 mass% on the flow behavior, viscosity, density, and surface tension of molten industrial blast furnace slag with CaO/SiO2 = 1.13 is investigated using a high‐temperature microscope, a rotating viscometer, and the maximum bubble pressure method. The measurement results show that Al2O3 acts as a network former in the studied CaO–SiO2–MgO–Al2O3–TiO2 slags. With an increase in the Al2O3 content from 10 to 20 mass%, the viscosity and surface tension of the slags increase and the density decreases. In contrast to Al2O3, the TiO2 acts as a surfactant and network breaker in the range of up to 15 mass%. The addition of TiO2 up to 15 mass% results in a decrease in the viscosity in the liquid‐dominated region and a decrease in the surface tension of the studied slags. Therefore, the density increases with the addition of TiO2 due to increasing molar volume. The behavior of the breakpoint temperature on all the viscosity curves is in complete agreement with the behavior of the flow point temperature and crystallization temperatures of melilite and perovskite.

Three-dimensional simulation of capillary rheometry for an estimation of extensional viscosity

Abstract: Abstract It is difficult to directly measure the steady extensional viscosity of thermoplastic composite materials, especially at high extension rates. The famous Cogswell method was derived analytically from the pressure drop of entrance flow in commercial capillary rheometers for estimating the extensional viscosity. However, using Cogswell´s extensional viscosity has always resulted in over-predictions of pressure drop. Recently, the GNF-X (eXtended Generalized Newtonian Fluid) model with a weighted shear/extensional viscosity was proposed to show the typical extension-induced vortex growth in entrance flow simulations. Under given various values of Trouton’s ratio for extensional viscosity, the GNF-X model is introduced to perform three-dimensional flow simulations of capillary rheometry over a range of apparent shear rates. The difference between the predicted pressure drops and the relevant experimental data is minimized such that the estimation of extensional viscosity is optimized herein.

Analysis of the efficiency of a rapid test for the early diagnosis of mastitis in cows

Abstract: This article describes the results of a study of the content of somatic cells in milk using various methods. Milk samples were tested using a standardized apparatus method using a Somatos-V viscometer, from which 3 groups of 20 samples were selected. The formation of groups was based on the content of somatic cells in the samples (up to 200; 200-400 and over 400 thousand/cm3). Further research was aimed at studying the diagnostic properties of the new test, the action of which is based on the suppression of foaming by mastitis milk. All samples were tested using the foam test and the California mastitis test. The coincidence of the results of the study of the studied test systems with the reference method was revealed in relation to samples containing a small (up to 200 thousand/cm3) and an increased (over 400 thousand/cm3) number of somatic cells. In samples with a cell concentration from 200 to 400 thousand/cm3, there are different results in the study by express testing methods. The foam test showed 90% and the California test showed 75% agreement with the results of viscometry. Given the difficulty in diagnosing latent mastitis, the foam test studied in this work may have promising prospects for use on farms for the early detection of sick cows. This method allows more accurately, qualitatively, to determine the increase in the number of somatic cells in milk, which is important in the diagnosis of latent subclinical mastitis and their timely treatment.

Morphological Effects on Natural Convection Heat Transfer of Magnesium Ferrite Ferrofluid

Abstract: This investigation intends to analyze the influence of nanoparticles morphology on the magnetic flux dependent thermo-physical properties and magnetohydrodynamic free convection heat transfer performance of water-based magnesium ferrite ferrofluid under various volume fractions. The thermo-physical parameters of the ferrofluid suspended with cube shaped particles are examined at 25 °C using KD2 pro thermal analyzer, Ostwald viscometer and specific gravity bottle under magnetic flux. The free convection heat transfer is obtained using heat pipes assisted cubical enclosure. Without the influence of magnetic flux, the thermal conductivity of the ferrofluid was improved by a maximum of 12.75% at a volume fraction of 0.15%. At the same time, the maximum viscosity and density were raised by 32.92% and 6.11% at a volume fraction of 0.20% in comparison with water. Under the influence of 350 Gauss, thermal conductivity, and viscosity of ferrofluid enhanced by 21.81% and 37.41% while the density decreased by 4.91%. It was revealed that the addition of cube-shaped magnesium ferrite particles in ferrofluid improved the thermo-physical properties. The optimum concentration for maximum heat transfer is reduced to 0.025% with the use of cube shaped particles compared to other types of nanoparticles reported in previous studies.

Structure, thermal stability and spinnability of the CaO-MgO-Al2O3-SiO2 glasses with SiO2 replaced by Al2O3

Abstract: In this paper, the structure, thermal stability, spinnability and fiber tensile strength of the CaO-MgO-Al2O3-SiO2 glasses with SiO2 replaced by Al2O3 were studied by FT-IR, DSC, dilatometry, rotating viscometer and tensile strength. Results show that with the molar ratio of Al2O3 to SiO2 (A/S) increasing, the polymerization degree of glass network structure increases, which results in a significant rise of Tg and thermal stability parameters (ΔT, S). The characteristic temperatures and fragility of glassy melts derived from viscosity tests and the MYEGA model increase with the ascent of A/S. The fiber spinnability parameters (Tl-Tlog3, Kfib) show a different trend as the A/S increases, but both indicating the feasibility of continuous fiberglass production, confirmed by experiments. The fiber tensile strength increases as the A/S increases or the fiber diameter decreases. Furthermore, with the same fiber diameter, the glass fiber produced at higher spinning temperature exhibits higher tensile strength

Traceability of the Micro Scale Pipe Viscometer for Traceable Calibration of Dynamic Viscosity

Abstract: Calibration of flow devices is important in several areas of pharmaceutical, flow chemistry and microfluidic applications where dosage of process liquids or accurate measurement of flow rate is important. The process-oriented liquid itself might influence the performance of a flow device and the simultaneous determination of dynamic viscosity under flow conditions might provide valuable information for process parameters. To offer simultaneous calibration of the dynamic viscosity of a process-oriented liquid at the corresponding flowrate, METAS built a pipe viscometer for the traceable inline measurement of dynamic viscosity in current flow facilities for low flowrates from 1 μL/min to 150 mL/min and pressure drops up to 10 bar. The traceability of all measuring quantities as well as geometrical dimensions of the microtube guarantee the traceability of the pipe viscometer to SI units. The most challenging part is the traceable determination of the inner diameter of the microtube. This can be achieved by measuring the pressure drop as a function of flowrate using a pipe viscometer and applying the Hagen–Poiseuille law with a traceable dynamic viscosity of a reference liquid (water) or performing measurements by utilizing the μ-CT facility at METAS, where the inner diameter is determined using X-ray diffraction. The validation of the stated measurement uncertainty of the pipe viscometer was performed by calibrating the dynamic viscosity of several reference liquids with traceable density and kinematic viscosity. The setup of the facility, traceability as well as uncertainty calculation of the pipe viscometer for inline measurement of dynamic viscosity are discussed in this paper.

Phase equilibrium, dynamics and rheology of phospholipid-ethanol mixtures: a combined molecular dynamics, NMR and viscometry study.

Abstract: Binary mixtures of ethanol and phospholipids DOPC and DOPE have been investigated in a composition range relevant for topical drug delivery applications. This was done using a combined computer simulation and experimental approach where molecular dynamics simulations of ethanol-lipid mixtures with different compositions were performed. Several key properties including diffusion coefficients, longitudinal relaxation times, and shear viscosity were computed. In addition, diffusion coefficients, viscosities and NMR longitudinal relaxation times were measured experimentally for comparison and in order to validate the results from simulation. Diffusion coefficients and relaxation times obtained from simulations are in good agreement with results from NMR and computed viscosities are in reasonable agreement with viscometry experiments indicating that the simulations provide a realistic description of the ethanol-phospholipid mixtures. Structural changes in the simulated systems were investigated using an analysis based on radial distribution functions. This showed that the structure of ethanol-DOPC mixtures remains essentially unchanged in the investigated concentration range while ethanol-DOPE mixtures undergo structural rearrangements with the tendency for forming small aggregates on the 100 ns time scale consisting of less than 10 lipids. Although our simulations and experiments indicate that no larger aggregates form, they also show that DOPE has stronger aggregation tendency than DOPC. This highlights the importance of the character of the lipid headgroup for lipid aggregation in ethanol and gives new insights into phase equilibrium, dynamics and rheology that could be valuable for the development of advanced topical drug delivery formulations.

Viscometer Readings Prediction of Flat Rheology Drilling Fluids Using Adaptive Neuro-Fuzzy Inference System

Abstract: Flat rheology drilling fluids are synthetic-based fluids designed to provide better drilling performance with flat rheological properties for deep water and/or cold environments. The detailed mud properties are mainly measured in laboratories and are often measured twice a day in the field. This prevents real-time mud performance optimization and negatively affects the decisions. If the real-time estimation of mud properties, which affects decision-making in time, is absent, the ROP may slow down, and serious drilling problems and severe economic losses may take place. Consequently, it is important to evaluate the mud properties while drilling to capture the dynamics of mudflow. Unlike other mud properties, mud density (MD) and Marsh funnel viscosity (MFV) are frequently measured every 15–20 minutes in the field. The objective of this study is to predict the viscometer readings at 300 and 600 RPM (R600 and R300) of the flat rheology mud in real-time using machine learning (ML) and then calculate the other rheological properties using the existing equations. The developed model using adaptive neuro-fuzzy inference system (ANFIS) predicted the viscometer readings with an acceptable accuracy. The maximum average absolute percentage error (AAPE) was less than 7 % and the correlation coefficient (R) was more than 0.96 for training, testing and validation.

Study on identification method of imported metallocene catalyzed polyethylene

Abstract: The imported polyethylene was analyzed by high temperature gel permeation chromatography, viscosity method, differential scanning calorimetry and inductively coupled plasma mass spectrometry. The molecular weight and its distribution, shear viscosity, thermodynamic properties, catalyst residues of several Ziegler-Natta catalyzed and metallocene catalyzed polyethylene were analyzed. The results show that most non-metallocene catalyzed polyethylene can be distinguished by high temperature gel permeation chromatography. Differential scanning calorimetry combined with capillary viscometry can effectively identify whether the sample belongs to single-site catalytic metallocene-catalyzed polyethylene or multi-site catalytic metallocene-catalyzed polyethylene. Finally, the ratio of Ti/Zr in the catalyst residue can be used to determine whether the sample belongs to metallocene-catalyzed polyethylene.

Investigation of Thermal Degradation Kinetics of Synthetic Polymers in High-Performance Water-Based Muds for Designing Drilling Automation Processes for Viscosity and Fluid-Loss Control

Abstract: For the purpose of engineering the drilling automation processes, it is necessary to explore the effects of thermal-degradation kinetics of synthetic polymers on the performance in different brine-based drilling muds in terms of time-dependent viscosity and fluid-loss control response. In this regard, three different synthetic acrylamide polymers with molecular weights between 2.8 to 3 million DU and sulfonation range between 15 to 40% are studied in sodium bromide (NaBr) brine based drilling mud systems. To achieve the substitution during the polymerization process, the sodium salt of 2-acrylamido-2-methyl-1-propane-sulfonic acid was utilized as a sulfonated monomer. The substitutions were verified by NMR testings. The time dynamics of these synthetic polymers were quantitatively investigated using a simple and reliable titration technique in order to comprehend the degradation kinetics at various temperatures. Viscosity and fluid loss testings in drilling muds were contrasted with the polymer degradation which were hot rolled at 250°F and 350°F for various time durations. Viscosity and fluid loss were calculated for variously aged fluids with a conventional viscometer and API & HTHP filter presses. The titration studies quantified the conversion of acrylamide molecules present in the polymer-chain into acrylic acid; the conversion represents the decay in polymer and was governed by the aging temperature and aging duration. The rate of polymer degradation decreased as the degree of sulfonation i.e., DoS in the polymer-chain increased, which was evident by a rise in Arrhenius activation energy. The drilling fluids which were hot rolled at 250°F showed a reasonable apparent viscosity in a range of 85 - 100 cp at room temperature and minimal HTHP fluid loss of 10 - 18 ml. Similarly, at 350°F hot rolling, all these fluids provided an apparent viscosity between 20 – 30 cp at room temperature with a HTHP fluid loss ranging from 36 – 42 ml. At both the temperature conditions, polymer with highest sulfonation provided a better control than other two polymers in terms of fluid loss and filter cake formation. These viscosity and fluid loss results were explained contradictorily with the effect of activation energy as sulfonation increased. In sodium bromide drilling muds, these results signified that higher sulfonation provides more thermal stability, but the polymer may be customized accordingly as per industry needs. In order to maintain viscosity and fluid loss management, this research discusses how the polymer degradation kinetics affect the time-dependent performance of synthetic acrylamide polymers in brine-based drilling fluids at high temperatures. Usage of sodium bromide salt provided sustained increase in the base-brine density and also provided conductive environment for sulfonated acrylamide polymers. This is essential for creating drilling automation in terms of polymer replenishment for specific downhole temperature conditions.

Prediction of the ribbon length to determine the viscosity of ladle-refining powder containing CaF2 using inclined plane test and advanced mathematical model

Abstract: In the present research, the inclined plane test (IPT) and an author-developed advanced mathematical model were used to determine the viscosity of ladle-refining + CaF2 powder containing 3–10% CaF2 (LRC powder). The ladle slag powder is composed of such compounds as CaO, Al2O3, SiO2 containing percentages of CaF2 to make special changes to the chemical and physical properties of the compound. The procedure for determination of the viscosity obtained by IPT method was supported using a high-temperature viscometer. The results showed that the ribbon lengths of LRC powder obtained by using the IPT method were related to an Arrhenius relationship of viscosity. Furthermore, from the advanced mathematical relationships, it was found that there is a very close relationship between the oxygen-to-silicon molar ratio (O/Si), basic/acidic oxide molar ratio (B/A), the number of non-bridging oxygen per tetrahedrally-coordinated atoms (NBO/T), and the chemical compositions of LRC powder. Hence, the advanced mathematical relationships from the software output, and Statistical Package for the Social Sciences (SPSS), were used to determine the prediction model of the viscosity of LRC powder based on its chemical composition. This model had a very good correlation with the actual values obtained.

Empirical model for fitting the viscosity of lithium bromide solution with CuO nanoparticles and E414

Abstract: To research viscosity fitting model of stable nano-lithium bromide solution (nano-LiBr), the stability of the nano-LiBr and the dynamic viscosity of LiBr were measued by Ultraviolet-visible spectroscopy (UV-vis) and rotational viscometer respectively. Two LiBr with different additives were measured, i.e., LiBr with dispersant (E414) and LiBr with dispersant + copper oxide nanoparticles (CuO). The ranges of measuring temperature were from 25°C–60°C, the concentrations of LiBr were from 50%–59%, the volume fractions of the dispersants were from 0%–4%, and the fractions of nanoparticle volume were from 0%–0.05%. Results indicated that the nano-LiBr with E414 had good stability. The viscosity of the LiBr decreased when temperature increased, and increased when LiBr concentration and dispersant amount were increased. It is also found that the viscosity was directly proportional to the volume fraction of the nanoparticles. This study also showed that the higher the concentration of the base fluid was, the more significant increase of the viscosity was. An empirical viscosity model of stable nano-LiBr with a maximum error of 13% was developed.

Rheological Characteristics of Fe–C–Cr(Ni) Alloys

Abstract: The principal objective of this project was to investigate the rheological properties of Fe–C–Cr and Fe–C–Ni-based low-alloy steels using an Anton Paar high-temperature rotational viscometer up to 1550 °C. The emphasis was placed on determining the liquidus temperatures and evaluating the flow and viscosity curves and the temperature dependence of dynamic viscosity. All were studied depending on the change in the content of chromium (0.010–4.863 wt%), nickel (0.001–4.495 wt%), and carbon (0.043–1.563 wt%). It was shown that the dynamic viscosity decreases with increasing nickel content and increases with increasing carbon and chromium content. The experimental data of the flow curves were fitted using the Herschel–Bulkley model with a good agreement between the measured and calculated values. Characterization of the internal structure was performed by SEM and EDX analyses, confirming non-significant changes in the microstructure of the original and remelted samples. The phase composition of the selected samples was also determined using JMatPro 12.0 simulation software (Sente Software Ltd., Guildford, UK).

Locust bean gum hydrogels are bioadhesive and improve indole-3-carbinol cutaneous permeation: influence of the polysaccharide concentration

Abstract: The locust bean gum (LBG) is a polysaccharide with thickening, stabilizing and gelling properties and it has been used in the preparation of pharmaceutical formulations. Hydrogels (HGs) are obtained from natural or synthetic materials that present interesting properties for skin application. This study aimed to develop HGs from LBG using indole-3-carbinol (I3C) as an asset model for cutaneous application. HGs were prepared by dispersing LBG (2%, 3% and 4% w/v) directly in cold water. The formulations showed content close to 0.5 mg/g (HPLC) and pH ranging from 7.25 to 7.41 (potentiometry). The spreadability factor (parallel plate method) was inversely proportional to LBG concentration. The rheological evaluation (rotational viscometer) demonstrated a non-Newtonian pseudoplastic flow behavior (Ostwald De Weale model), which is interesting for cutaneous application. The HET-CAM evaluation showed the non-irritating characteristic of the formulations. The bioadhesive potential demonstrated bioadhesion in a concentration-dependent manner. Permeation in human skin using Franz cells showed that the highest LBG concentration improved the skin distribution profile with greater I3C amounts in the viable skin layers. The present study demonstrated the feasibility of preparing HGs with LBG and the formulation with the highest polymer concentration was the most promising to transport active ingredients through the skin.

Structural transformations of DNA under the influence of oligomers and polymers of ethylene glycols

Abstract: In this work, the effect of ethylene glycol oligomers and polymers of various molecular masses on the structural transformations of deoxyribonucleic acid (DNA) is studied exclusively by viscometry. The main goal of this study was to understand how polyethylene glycol (PEG) interacts, which binds to calf thymus DNA (ctDNA). This paper presents the results of these studies. It has been found that ethylene glycols with molecular masses of 600 and 1000, apparently due to their smallness, do not have a noticeable effect on the sizes of DNA macromolecules in the studied concentration ranges. For ethylene glycols with molecular masses of 6000 and 7000, a clearly expressed complex course of the dependence of the intrinsic viscosity of DNA solutions on the polymer content was established. A decrease in the viscosity of solutions was observed, which was interpreted as a result of a decrease in the size of DNA macromolecules. It was assumed that with a change in the concentration of ethylene glycols in the system, an increase in the density of DNA macromolecules occurs due to a change in the balance of hydrophobic-hydrophilic interactions. The results of the study in the presence of 20 000 molecular masses of PEG in a DNA solution practically exclude the presence of interaction between DNA and PEG molecules at such molecular masses. Այս աշխատանքում բացառապես մածուցիկության մեթոդով ուսումնասիրվել է էթի-լենգլիկոլի օլիգոմերների և տարբեր մոլեկուլային զանգվածներով պոլիմերների ազդեցությունը դեզօքսիռիբոնուկլեինաթթվի (ԴՆԹ) կառուցվածքային փոխակերպումների վրա։ Հետազոտության հիմնական նպատակն էր հասկանալ, թե ինչպես է փոխազդում պոլիէթիլենգլիկոլը (ՊէԳ), որը կապվում է հորթի նշագեղձի ԴՆԹ-ին (հնԴՆԹ): Ներկա հոդվածը ներկայացնում է այդ ուսումնասիրությունների արդյունքները: Պարզվել է, որ 600 և 1000 մոլեկուլային զանգվածներով էթիլենգլիկոլները, ըստ երևույթին, իրենց փոքրության պատճառով, նկատելի ազդեցություն չունեն ԴՆԹ-ի մակրոմոլեկուլների չափերի վրա ուսումնասիրված կոնցենտրացիաների միջակայքում: 6000 և 7000 մոլեկուլային զանգվածներով էթիլենգլիկոլների համար հստակ արտահայտված բարդ ընթացք է հաստատվել ԴՆԹ-ի պոլիմերների պարունակությունից լուծույթների ներքին մածուցիկության կախվածության համար: Նկատվել է լուծույթների մածուցիկության նվազում, որը մեկնաբանվել է որպես ԴՆԹ մակրոմոլեկուլների չափերի նվազման արդյունք։ Ենթադրվում է, որ համակարգում էթիլենգլիկոլների կոնցենտրացիայի փոփոխության ընթացքում ԴՆԹ-ի մակրոմոլեկուլների խտության աճ է տեղի ունենում հիդրոֆոբ-հիդրոֆիլ փոխազդեցությունների հավասարակշռության փոփոխության պատճառով: Հետազոտության արդյունքները ԴՆԹ լուծույթում ՊԷԳ-ի 20000 մոլեկուլային զանգվածով նմուշների առկայության պայմաններում գործնականում բացառվում է փոխազդեցության առկայությունը ԴՆԹ-ի և ՊԷԳ-ի մոլեկուլների միջև նման մոլեկուլային զանգվածների դեպքում: В данной работе исключительно методом вискозиметрии изучено влияние олигомеров и полимеров этиленгликоля различной молекулярной массы на структурные превращения дезоксирибонуклеиновой кислоты (ДНК). Основная цель этого исследования состояла в том, чтобы понять, как взаимодействует полиэтиленгликоль (ПЭГ), который связывается с ДНК тимуса теленка (цтДНК). В данной работе представлены результаты этих исследований. Установлено, что этиленгликоли с молекулярными массами 600 и 1000, по-видимому, в силу своей малости, не оказывают заметного влияния на размеры макромолекул ДНК в исследованных диапазонах концентраций. Для этиленгликолей с молекулярными массами 6000 и 7000 установлен четко выраженный сложный ход зависимости характеристической вязкости растворов ДНК от содержания полимера. Наблюдалось снижение вязкости растворов, что интерпретировалось как результат уменьшения размеров макромолекул ДНК. Предполагалось, что при изменении концентрации этиленгликолей в системе происходит увеличение плотности макромолекул ДНК за счет изменения баланса гидро-фобно-гидрофильных взаимодействий. Результаты исследования в присутствии 20 000 молекулярных масс ПЭГ в растворе ДНК практически исключают наличие взаимодействия молекул ДНК и ПЭГ при таких молекулярных массах.