Viscosity Measurements Research Articles

Formulation Development and Evaluation of Polyherbal Emulgel for Anti Inflammatory Activity

This study focuses on the formulation development and evaluation of a polyherbal emulgel incorporating curcumin and coriander seed oil, aimed at enhancing anti-inflammatory activity. Preformulation studies were conducted to characterize the physical, chemical, and mechanical properties of the active substances, and to establish a robust basis for the formulation approach. Various parameters including solubility, melting point, partition coefficient, and drug-excipient interactions were assessed to ensure compatibility and efficacy. The emulgel was prepared through a systematic process involving the preparation of a gel base, oil phase, aqueous phase, and subsequent emulsification. The final product was evaluated for various properties such as physical appearance, homogeneity, pH, spreadability, extrudability, swelling index, viscosity, drug content, and in vitro drug diffusion. Stability studies were also conducted over three months to ensure the longevity and reliability of the formulation. Results indicated that the formulated emulgel exhibited desirable physical properties, optimal pH, high spreadability, good extrudability, and a significant swelling index. Viscosity measurements confirmed appropriate consistency, while drug content analysis ensured accurate dosing. In vitro drug release studies demonstrated sustained release profiles, fitting well with kinetic models. Additionally, in vivo anti-inflammatory activity was assessed using a carrageenan-induced paw edema model in rats, showing promising results with notable inhibition of inflammation. Overall, the polyherbal emulgel formulation developed in this study offers a promising alternative for anti-inflammatory therapy, combining the therapeutic benefits of curcumin and coriander seed oil in a stable and effective dosage form. Further studies are recommended to explore clinical efficacy and potential applications in broader therapeutic areas

Microfluidic Rheology: An Innovative Method for Viscosity Measurement of Gels and Various Pharmaceuticals

Measuring the viscosity of pharmaceutical dosage forms is a crucial process. Viscosity provides information about the stability of the composition, the release rate of the drug, bioavailability, and, in the case of injectable drug formulations, even the force required for injection. However, measuring viscosity is a complex task with numerous challenges, especially for non-Newtonian materials, which include most pharmaceutical formulations, such as gels. Selecting the appropriate shear rate is critical. Since viscosity in many systems is highly temperature-dependent, stable temperature control is necessary during the measurement. Using microfluidics technology, it is now possible to perform rheological characterization and conduct fast and accurate measurements. Small sample volumes (even below 500 µL) are required, and viscosity determination can be carried out over a wide range of shear rates. Nevertheless, the pharmaceutical application of viscometers operating on the principle of microfluidics is not yet widespread. In our work, we compare the results of measurements taken with a microfluidic chip-based viscometer on different pharmaceutical forms (gels, solution) with those obtained using a traditional rotational viscometer, evaluating the relative advantages and disadvantages of the different methods. The microfluidics-based method enables time- and sample-efficient viscosity analysis of the examined pharmaceutical forms.

The conjoint effect of lab-grown nano-graphene dispersant and omega-9 fatty acid surfactant on performance of CI engine

This article aims to assess the performance characteristics of lab-grown graphene nanoparticles via electrolytic exfoliation as nano additives in engine oil. Physical characterization confirmed the morphology and purity of the prepared graphene nanoparticles. Nanolubricants were prepared at 0.1%, 0.2%, and 0.3% volume fraction of the nanoparticles with the addition of oleic acid as surfactant. Measurements of density and viscosity for the nanolubricants were recorded at varying concentrations and temperatures. The performance parameters of a 4-stroke single-cylinder compression ignition (CI) engine were computed using the formulated nanolubricants. The emission of toxic gases into the environment post-engine performance evaluation was also analyzed for different formulations of nanolubricant samples. Results showed that the relative viscosity variation with concentration for the experimental data was in well agreement with other available predictive models. The nanolubricant with 0.1% concentration yielded a reduction of 13.96 ± 0.39% in total fuel consumption (TFC), a reduction of 5.55 ± 0.17% in brake-specific fuel consumption (BSFC) and an augmentation of 3.96 ± 0.13% in brake thermal efficiency (BTE) in comparison to plain engine oil and other prepared formulations. Also, a marginal reduction in emission of exhaust toxic gases i.e., (2.13 ± 0.1%) ppm in NOx and a significant maximum reduction of 7.46 ± 0.2% in smoke opacity has been obtained with 0.1% nanolubricant sample as compared to other test samples. The results from the present study may be useful for developing sustainable nanolubricants for environmental viability and energy savings.

Comparative Linkage of Novel Anti-Tumor Pd(II) Complex with Bio-Macromulecules: Fluorescence, UV-Vis, DFT, Molecular Docking and Molecular Dynamics Simulation Studies.

A novel mononuclear palladium complex, [Pd(dach)(SSA)], where dach and SSA are diaminocyclohexane and sulfosalicylic acid ligands, respectively, has been synthesized and identified utilizing analytical and spectral methods. DFT calculations, namely geometry optimization, MEP, HOMO-LUMO and NBO analysis, have been conducted at B3LYP level by aug-ccpVTZ-PP and 6-311G(d, p) basis sets. NBO and HOMO-LUMO analysis exhibited that the palladium compound is stable. MEP showed the potential sites of molecule for the interaction. By employing MTT assay, the cytotoxicity activity of the aforesaid compound was examined on K562 cell line, which revealed a proper activity compared to cisplatin. To ascertain the lipophilicity of the newly made compound, the partition coefficient measurement was accomplished, which follows the order of cisplatin < Pd(II) complex. Next, investigation of binding properties of the studied compound with DNA of calf thymus and BSA were done by spectroscopic (CD, fluorescence emission and electronic adsorption) and non-spectroscopic (viscosity measurements, DNA gel electrophoresis, molecular docking and molecular dynamics simulation) methods. The outcomes of CD and UV-Vis spectroscopy demonstrated that the title compound refolded the protein via increasing the alpha helix percentage. The data obtained from UV-Vis studies indicated the non-intercalative mutual action between Pd(II) complex with DNA. It also revealed that the Kapp magnitude of CT-DNA (7.43 × 104 M- 1) is higher than the BSA (5.17 × 103 M- 1), and L1/2 (midpoint of transition) of CT-DNA (5 µM) is lower than the BSA (5.7 µM), indicating that the complex has a greater binding affinity to CT-DNA than BSA. Fluorescence quenching mechanism of the two biomolecules by the metal complex is static and the calculated thermodynamic parameters (ΔS° < 0 and ΔH° < 0) suggested the hydrogen bonding and/ or van der Waals forces with DNA and BSA. Further, molecular docking indicated that the studied compound fits into the groove of DNA and the site I of BSA. The stability of metal compound-DNA/-BSA in the presence of H2O solvent and over the time were validated via molecular dynamics simulation.

Machine learning prediction of methane, nitrogen, and natural gas mixture viscosities under normal and harsh conditions

The accurate estimation of gas viscosity remains a pivotal concern for petroleum engineers, exerting substantial influence on the modeling efficacy of natural gas operations. Due to their time-consuming and costly nature, experimental measurements of gas viscosity are challenging. Data-based machine learning (ML) techniques afford a resourceful and less exhausting substitution, aiding research and industry at gas modeling that is incredible to reach in the laboratory. Statistical approaches were used to analyze the experimental data before applying machine learning. Seven machine learning techniques specifically Linear Regression, random forest (RF), decision trees, gradient boosting, K-nearest neighbors, Nu support vector regression (NuSVR), and artificial neural network (ANN) were applied for the prediction of methane (CH4), nitrogen (N2), and natural gas mixture viscosities. More than 4304 datasets from real experimental data utilizing pressure, temperature, and gas density were employed for developing ML models. Furthermore, three novel correlations have developed for the viscosity of CH4, N2, and composite gas using ANN. Results revealed that models and anticipated correlations predicted methane, nitrogen, and natural gas mixture viscosities with high precision. Results designated that the ANN, RF, and gradient Boosting models have performed better with a coefficient of determination (R2) of 0.99 for testing data sets of methane, nitrogen, and natural gas mixture viscosities. However, linear regression and NuSVR have performed poorly with a coefficient of determination (R2) of 0.07 and − 0.01 respectively for testing data sets of nitrogen viscosity. Such machine learning models offer the industry and research a cost-effective and fast tool for accurately approximating the viscosities of methane, nitrogen, and gas mixture under normal and harsh conditions.

Understanding Ultrasonic Wave Behavior in Liquid Media: A Comprehensive Overview

To comprehensively understand molecular processes, it is essential to analyze how thermodynamic parameters change with temperature and composition, providing valuable insights into molecular interactions. The industry's demand for precise information on the physical and chemical characteristics of different liquid combinations underscores the importance of such research. Researchers employ an ultrasonic interferometer for measuring ultrasonic wave velocity, a specific gravity bottle for liquid density determination, and an Ostwald viscometer for viscosity measurements. The propagation of ultrasonic waves can affect the physical properties of a medium, providing insights into the physics of liquids and solutions. Research has explored how frequency and temperature can impact thermoacoustic characteristics. Scientists have identified the nature of the forces between molecules, including hydrogen bonds, charge transfer complexes, and the breaking and formation of such bonds through their investigations. By measuring ultrasonic wave velocity, liquid density, and viscosity, researchers can analyze a range of acoustic and thermodynamic properties, thus significantly advancing our understanding of molecular interactions within each sample. Additionally, a comprehensive explanation of the measured parameters is provided to offer detailed insights into the studied phenomena, enhancing the overall understanding of molecular processes in liquid mixtures.

Catalytic Cracking of Crude Palm Oil into Biogasoline Over HZSM-5 and USY-Zeolite Catalysts: A Comparative Study

This study comprehensively evaluated HZSM-5 and USY-Zeolite as catalysts for producing biogasoline from crude palm oil through a catalytic cracking method, including uncertainty analysis. This study utilized HZSM-5 and USY-Zeolite as catalysts with crude palm oil (CPO) concentration ratios of 1:50, 1:75, 1:100, and 1:125. USY-Zeolite (19.06%) exhibited a higher biogasoline yield than HZSM-5 (39.56%) because of its optimal pore structure, as proven by N₂ physisorption characterization. Physicochemical characterization of biogasoline included flash point, viscosity, boiling point, and octane number measurements. Gas chromatography-mass spectrometry (GC-MS) was used to determine the chemical composition of biogasoline. An elevated catalyst ratio results in reduced liquid yields and biogasoline fractions. At a ratio of 1:125, the HZSM-5 catalyst produced the highest biogasoline yield (39.56%). GC-MS analysis revealed that biogasoline contained various hydrocarbons and oxygenated compounds. Life cycle assessment (LCA) also demonstrated that this method can reduce the scarcity of mineral and fossil resources by 85% and 35%, respectively. Biogasoline's physical and chemical characteristics are significantly impacted by the type of catalyst and its various modifications. This study provides evidence that the catalytic cracking technique is suitable for producing biogasoline from CPO and yields positive results.

Surface light scattering: The capability of precisely measuring the interfacial properties of Newtonian fluids within the capillary wave transition region

This work employs a theoretical power spectrum of the dynamics of surface fluctuations in the frequency domain to elucidate the dissipation of capillary waves of fluids in the near-critical oscillation or transition region, seeking to resolve the problem of large discrepancies in viscosity and surface tension measurements in the region. The frequency-domain analysis approach was suggested, involving the discrete Fourier transform to transform the time domain data to the frequency domain and the fitting algorithm for the power spectrum. A total of three refrigerants, four alkanes and six fatty esters were chosen to examine the approach, with a range of the dimensionless number Y between 1.3 and 101.9. The findings demonstrate that frequency-domain approach is an effective way of dealing with dissipation issues for surface light scattering method when approaching the critical oscillation region, and thus could extend the technique for determining the viscosity and surface tension of Newtonian fluids to a sufficient wide viscosity range.

Exploring tear viscosity with quartz crystal microbalance technology.

Tear viscosity is a critical property affecting tear distribution and ocular surface stability. While not widely established as a primary diagnostic marker, deviations from normal viscosity can impact ocular health, potentially contributing to conditions such as dry eye syndrome. Despite their importance, traditional viscometers require sample volumes that are not feasible to use with tear volume. This research introduces a novel Quartz Crystal Microbalance (QCM)-based method for tear viscosity measurement, offering a viscometer prototype that operates with minimal sample volumes. Human tear samples, solutions used in artificial eye drops, and various commercial eye drop brands were evaluated. Results show that the QCM method aligns with established viscosity ranges. The average viscosity of healthy human tears was found to be 1.73 ± 0.61 cP, aligning with the typical range of 1-10 cP. Variability in the viscositiesof eye drop can be attributed to differences in their chemical compositions. The QCM method offers benefits such as reduced sample consumption and rapid results, enhancing understanding of tear dynamics for ocular health. Further research with larger sample sizes is needed to establish normative viscosity values in healthy individuals and those with dry eye syndrome, which is crucial for validating the device's clinical efficacy.

A golgi targeting viscosity rotor for cancer diagnosis in living cells and tissues

Unveiling the intricate relationship between cancer and Golgi viscosity remains an arduous endeavor, primarily due to the lack of Golgi-specific fluorescent probes tailored for viscosity measurement. Considering this formidable obstacle, we have triumphed over the challenge by devising a bespoke Golgi-specific viscosity probe, aptly named GOL-V. This ingenious innovation comprises the viscosity rotor BODIPY intricately tethered to the Golgi-targeting moiety benzsulfamide. GOL-V exhibits remarkable sensitivity to fluctuations in viscosity, the fluorescence intensity of GOL-V increased 114-fold when the viscosity value was increased from 2.63 to 937.28 cP. Owing to its remarkable capacity to suppress the TICT state under conditions of heightened viscosity. Moreover, its efficacy in sensitively monitoring Golgi viscosity alterations within living cells is also very significant. Astonishingly, our endeavors have culminated in not only the visualization of Golgi viscosity at the cellular and tissue levels but also in the clinical tissue samples procured from cancer patients. Harnessing the prowess of GOL-V, we have successfully demonstrated that Golgi viscosity could serve as a discerning marker for detecting the presence of cancer. The convergence of these exceptional attributes firmly establishes GOL-V as an immensely potent instrument, holding immense potential in the realm of cancer diagnosis.

A Compact Differential Dynamic Microscopy-based Device (cDDM): An Approach Tool for Early Detection of Hypercoagulable State in Transfusion-Dependent-β-Thalassemia Patients.

β-Thalassemia especially transfusion-dependent thalassemia (TDT) associates with a hypercoagulable state, which is the main cause of thromboembolic events (TEE). Plasma viscosity and rheological parameters could be essential markers for determining hypercoagulable state in β-thalassemia patients. The traditional methods for measuring viscosity are often limited by large sample volumes and are impractical for routine clinical monitoring. The compact differential dynamic microscopy-based device (cDDM), an optical microscopy for quantitative rheological assessment, was developed and applied for prognosis of the hypercoagulable state in β-TDT with and without splenectomy. The device was performed plasma viscosity measurement using low plasma volume (8 μL) and revealed a value as modulus of complex viscosity |η(ω)| in 7 min. We also parallelly demonstrated the correlation of the viscosity and related-coagulable parameters: complete blood count, prothrombin time (PT), activated partial thromboplastin time (APTT), protein C (PC), protein S (PS), CD62P and CD63 expression, and platelet aggregation test. The thalassemia plasma exhibited a higher value of |η(ω)| than healthy plasma, which can represent a different viscoelastic property among the groups. Even all related-coagulable parameters indicated hypercoagulable state in both nonsplenectomies and splenectomies β-TDT patients when compared to control, only high platelet numbers significantly correlated to high plasma viscosity in the splenectomy group. However, the other coagulable parameters have shown a trend of positive relationship with high plasma viscosity in all β-1thalassemia TDT patients. The relative results suggested that our device would be an approach tool for early detection of hypercoagulable state in transfusion-dependent-β-thalassemia patients, which can help to prevent TEE and the critical consequent-complications.

Unified Understanding of the Structure, Thermodynamics, and Diffusion of Single-Chain Nanoparticle Fluids.

Single-chain nanoparticles (SCNPs) are a fascinating class of soft nano-objects with promising properties and relevance to protein condensates, polymer nanocomposites, nanomedicine, bioimaging, catalysis, and drug delivery. We combine molecular dynamics simulations and equilibrium and time-dependent statistical mechanical theory to construct a unified understanding of how the internal conformational structure of SCNPs, of both a simple fractal globule-like form and more complex objects with multiple internal intermediate length scales, determines nm-scale intermolecular packing correlations, thermodynamic properties, and center-of-mass diffusion over a wide range of concentrations up to dense melts. The intermolecular pair correlations generically exhibit a distinctive deep correlation hole form due to SCNP internal connectivity structure and repulsive interparticle interactions associated with a globular-like conformation on the macromolecular scale, with concentration-dependent deviations at small separations. Unanticipated exponential-like dependences of the equation-of-state, osmotic compressibility, and center-of-mass diffusion constant on SCNP macromolecular packing fraction are theoretically predicted and confirmed via simulations. System-specific behaviors are found associated with SCNP internal structure, but overarching regularities are identified and understood based on a generalized effective globule conformation on macromolecular scales. Diffusivity slows down by 2-3 decades with increasing concentration and is understood as a consequence of a nonactivated excluded volume-driven weak-caging process associated with space-time correlated intermolecular forces experienced by the SCNP. Good agreement between the theory and simulations is established, testable predictions are made, and a quantitative comparison with viscosity measurements on a specific SCNP fluid is carried out. The basic theoretical approach can potentially be extended to treat the chemical and physical consequences of varying the structure of other classes of soft nanoparticles with distinctive internal nanoscale organization relevant in nanotechnology and nanomedicine, and the possible emergence of macromolecular kinetically arrested glasses.

Interaction-Based Perspective for Designing Polymer Biomaterial: A Strategic Approach to the Chitosan-Glycerophosphate System.

The conventional approach for developing any polymeric biomaterial is to follow protocols available in the literature and/or perform trial-and-error runs without a scientific basis. Here, we propose an analysis of a complex overlay of molecular interactions between drugs and polymers that provides a strategic pathway for biomaterial development. First, this work provides an innovative interaction-based method for developing an ocular formulation involving in situ gelling chitosan, gelatin, and glycerophosphate systems. A systematic interaction study is conducted based on the measurement of hydrodynamic radius, zeta potential, and viscosity with the sequential addition of formulation components. The increase in the hydrodynamic radius of the polymer with the addition of drugs can be interpreted as better diffusion of the drug inside the charged polymer chains and vice versa. Based on the knowledge of these interactions, a formulation has been designed that shows better drug release results with extended and sustained release compared to literature protocols, hence accentuating the importance of this study. An in-depth analysis of interactions can lead to a better understanding of the system. Second, we demonstrate the development of two dual-drug biomaterial systems, i.e., an in situ gelling and a liquid formulation at ocular surface temperature from the same polymers, which can be used as an ocular antiglaucoma formulation. Prior knowledge of the interactions between the drug polymers can be used to design a better formulation. The demonstrated application of this interaction-based protocol development can be extended universally to any biomaterial. This would provide a comprehensive idea about the properties and interactions of polymers and drugs, which can also serve as a base/starting point for a new formulation/biomaterial development.

Application of the Hybrid Model to elastohydrodynamic lubrication (EHL) Reference Liquids for Pressure Extrapolation

Reference liquids can be useful in the new quantitative approach to elastohydrodynamic lubrication calculations only if the properties of these liquids are accurately modeled. The pressures in the contact sometimes exceed the pressures of the available viscometer measurements, requiring extrapolation. The previtreous piezoviscous response is always faster-than-exponential with an apparent divergence pressure. Therefore, any model used for extrapolation must possess these characteristics and up to now published work in EHL, where extrapolation of the viscosity of squalane is performed, has not. To date, the only model that has been shown to accurately extrapolate to high pressure is the Hybrid model. This expression was applied to six reference liquids for use in quantitative investigations in EHL. Viscosity measurements for trioctyl trimellitate were extended to 1.1 GPa. The results obtained with high pressure viscometers are preferable over molecular dynamics results if they are different. Molecular dynamics calculations are not currently capable of reliable results for viscosity at very high pressures.

Acrylamide Cross‐Linked Psyllium Polysaccharide with Improved Flocculation Performance for the Removal of Microplastics from Water

AbstractThis article presents a novel material of acrylamide (AM) cross‐linked psyllium polysaccharides (PLP) derivative, PLP‐AM, which can be used as an effective polymeric flocculant for the removal of microplastics (MP) from water. PLP‐AM was produced by radical polymerization of PLP and AM using microwave irradiation instead of conventional radical initiators. The characterization of PLP‐AM was carried out by FT‐IR spectroscopy, elemental analysis, intrinsic viscosity measurement and thermogravimetric analysis (TG). Polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) were utilized to examine the flocculation performance of PLP‐AM. The optimum flocculation conditions were obtained by the comprehensive exploration of flocculant concentration, solution pH and temperature. In a solution with a pH 6 at 30 °C, the maximum removal percentages of PS and PVC by 60 mg/L of PLP‐AM were 92.55 % and 94.31 %, respectively, while 93.85 % of the maximum removal of PET percentage could be obtained by 80 mg/L of PLP‐AM. The results of zeta potential measurement revealed that there was adsorption electric neutralization between MP and PLP‐AM besides the adsorption bridging mechanism. These results suggest that PLP‐AM may bring an inspiration for the development of polymer flocculant to remove MP from water.

Physical properties of soft contact lens multipurpose solutions commercially available in Ghana

PurposeTo investigate the physical properties of commercially available multipurpose soft contact lens solutions in Ghana. MethodspH (Kelilong ICL-099 pH meter, China), osmolality (OSMOMAT 3000, GONOTEC, Germany), surface tension (Sigma 700 Tensiometer, Sweden), and viscosity (CFOC-200 Viscometer, Cannon Company, USA) of various soft contact lens multipurpose solutions (MPS) were measured in triplicates at room temperature. Viscosity measurements were also taken at 34 °C ocular surface temperature. The solutions examined were Opti-Free Replenish (OFR), Trufresh (TF), Avizor (AV), Freshlook (FL), and Refresh (RF). ResultsSeveral solutions were largely hypo-osmotic in the range of 108–231 mOsm/kg, the exception being Avizor, which had osmolality values that were closer to human tears (301 ± 0.58 mOsm/kg). The range of pH values of the solutions (6.33–8.24, mean (SD) = 7.53 ± 0.18) fell within the reported tolerable range for the ocular surface (6.20–9.00). Surface tension values ranged from 35.86 to 42.27 mNm with a mean of 38.49 ± 2.32 mNm. The average viscosity of most solutions at room temperature (25 °C) was 1.44 ± 0.49 cP with a range of 1.04–2.15 cP. Significantly lower values ranging from 0.79 to 1.58 cP were obtained at ocular surface temperature (34 °C), p = 0.0001). ConclusionsThe physical properties of many of the solutions used as MPS in Ghana are markedly variable. Nevertheless, pH, surface tension, and viscosity fall within the acceptable limits of ocular physiological tolerance; except for osmolality, which majority were outside the reported tolerable range for the ocular surface. This information may partly explain the reason some patients exhibit strong preferences for certain care systems and should aid clinical decision-making when prescribing eye care systems to patients.

A new portable penetrometer for measuring the viscosity of active lava.

Viscosity is a fundamental physical property of lava that dictates style and rate of effusive transport. Studies of lava viscosity have predominantly focused on measuring re-melted rocks in the laboratory. While these measurements are well-constrained in temperature, shear rate, and oxygen fugacity, they cannot reproduce the complexities of the natural emplacement environment. Field viscosity measurements of active lava are the only way to fully capture lava's properties, but such measurements are scarce, largely due to a lack of easy-to-use, portable, and accurate measurement devices. Thus, there is a need for developing suitable field instruments to help bolster the understanding of lava. Here, we present a new penetrometer capable of measuring a material's viscosity under the harsh conditions of natural lava emplacement. This device uses a stainless-steel tube with a semi-spherical tip fixed to a load cell that records axial force when pushed into a material, while simultaneously measuring the penetration depth via a free-moving tube that is pushed backward along the penetration tube. The device is portable (1.5m long, 5.5kg in weight) and uses a single-board computer for data acquisition. The penetrometer has an operational range from 2.5 × 102 to 2.1 × 105Pas and was calibrated for viscosities ranging from 5.0 × 102 to 1.6 × 105Pas. It was deployed to the 2023 Litli-Hrútur eruption in Iceland. These field measurements successfully recorded the in situ viscosities of the lava in the range of 1.2 × 104-3.4 × 104Pas, showcasing it as an efficient method of measuring natural lava viscosity.

Relation between the viscosity and electrical conductivity of molten slag for coal gasification and their dependence on SiO2 content

Direct measurement of coal ash viscosity during coal gasification in slag-tapping gasifiers poses a considerable challenge. Molten slag with different viscosities (η) possesses various electrical conductivities (κ). This study explores the relation between η and κ as a potential method for evaluating slag viscosity during coal gasification. The role of SiO2, a major component in coal ash, in η and κ was clarified based on the characterization of structural units of aluminosilicates in the slag through Fourier transform infrared spectroscopy and Raman analysis. Results indicated that an increase in SiO2 addition caused a decrease of κ and an increase in the activation energies of both κ (Eκ) and η (Eη). In particular, when the addition was 2%, η exhibited a fluctuation, and when the addition was 6%, a decoupling was observed between η and κ. Such phenomena are intricately linked to the content of the SiO4 unit structure (Qn(Si)) and its polymerization degree within the melt structure, and η is less sensitive to structural alterations than κ.

Limits for safe viscosity measurement of non-colloidal suspensions in rotational rheometry—a numerical simulation-based approach

Limits for safe viscosity measurement of non-colloidal suspensions in rotational rheometry—a numerical simulation-based approach

Synthesis and characterization of amino-functionalized guar gum based polyurea: Preparation of iodine complexes, structural investigation and release studies

Biobased materials are expanding dramatically in various industrial applications due to their unique intrinsic properties. In this study, various chemical functionalization procedures were used to synthesize guar gum, a naturally occurring polysaccharide-based polyurea, and its iodine complexes. Firstly, guar gum was subjected to tosylation reaction using p-toluene sulphonyl chloride to introduce tosyl moieties in the polymer chain with the degree of substitution (DS) ranging between 0.16 and 1.54. Sample having the highest degree of tosyl moiety was further reacted with tris(2-aminoethyl) amine to produce 6-deoxy-6-tris(2-aminoethyl) amine derivative via nucleophilic substitution reaction to impart amino functional groups. The degree of substitution in 6-deoxy-6-tris(2-aminoethyl) amine derivative was found to be 0.59. 6-deoxy-6-tris(2-aminoethyl) amine derivative was reacted with different diisocyanates (Toluene-2,4-diisocyanate (TDI), 1,6-diisocyanatohexane (HMDI)) to produce guar gum based polyurea. Iodine complexes of the resulting polyurea were prepared by reacting with different iodinating agents. Different chemical reactions, formation of polyurea and its iodine complexes were thoroughly analyzed by different analytical techniques such as FT-IR, NMR, elemental analysis, XRD, UV–Vis spectroscopy, and a reaction scheme has been proposed. Morphological and rheological characteristics were analyzed by SEM and viscosity measurement. Thermal analysis was carried out by TGA and DSC studies. Finally, by examining the complex's UV–Vis spectra, the iodine release characteristics from polyurea‑iodine complexes were investigated.