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Journal articles on the topic 'Dispersion'
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Mohammad Hadi, Mohammad Hadi, Farokh Marvasti Farokh Marvasti, and and Mohammad Reza Pakravan and Mohammad Reza Pakravan. "Dispersion compensation using high-positive dispersive optical fibers." Chinese Optics Letters 15, no. 3 (2017): 030601–30605. http://dx.doi.org/10.3788/col201715.030601.
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Thonglerth, P., P. Sujaridworakun, and O. Boondamnoen. "Preparation of ZnO Nanoparticles Water-based Dispersion." Journal of Physics: Conference Series 2175, no. 1 (January 1, 2022): 012029. http://dx.doi.org/10.1088/1742-6596/2175/1/012029.
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Abstract In this work, an attempt was made to stabilize ZnO NPs as water-based dispersion. The dispersing agents used are 3-glycidoxypropyltrimethoxysilane (GPTMS), polyvinyl alcohol (PVA) and oleic acid (OA). These dispersing agents were combined with sodium dodecyl sulfate (SDS) to facilitate better dispersion stability. Different wt% content of modified ZnO NPs such as 0.2, 0.4, 1 and 3% w/v was used at a fixed ratio of ZnO NPs:SDS:dispersing agent. The highest dispersion stability was achieved at 1% w/v content of modified ZnO NP, whereas some precipitate was observed at 3% w/v. The result reveals that sonication at 30 minutes produced the highest dispersion stability whereas extended sonication led to re-agglomeration of ZnO NPs. The optimum ratio of ZnO NPs:SDS:dispersing agent which produced about 98% dispersion stability was at 1:0.25:0.2. The zeta potential (ZP) values of ZnO NPs/GPTMS, ZnO NPs/PVA, and ZnO NPs/OA dispersions are -51, -29 and -15 mV, respectively. The ZP values was influenced by the electrical charge surrounding the particles which was also caused by the functional group of the dispersing agents. However, the stabilization mechanisms of modified ZnO NPs in water was complicated. It did not only depend on the electrostatic value but also on electrosteric stabilization caused by the steric effects hindering the dispersing agents. Interactions between the dispersing agents and ZnO NPs was confirmed through FTIR analysis.
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Mavko, Gary, and Diane Jizba. "The relation between seismic P‐ and S‐wave velocity dispersion in saturated rocks." GEOPHYSICS 59, no. 1 (January 1994): 87–92. http://dx.doi.org/10.1190/1.1443537.
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Seismic velocity dispersionin fluid-saturated rocks appears to be dominated by tow mecahnisms: the large scale mechanism modeled by Biot, and the local flow or squirt mecahnism. The tow mechanisms can be distuinguished by the ratio of P-to S-wave dispersions, or more conbeniently, by the ratio of dynamic bulk to shear compliance dispersions derived from the wave velocities. Our formulation suggests that when local flow denominates, the dispersion of the shear compliance will be approximately 4/15 the dispersion of the compressibility. When the Biot mechanism dominates, the constant of proportionality is much smaller. Our examination of ultrasonic velocities from 40 sandstones and granites shows that most, but not all, of the samples were dominated by local flow dispersion, particularly at effective pressures below 40 MPa.
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Khatry, Sadhna, Neha Sood, and Sandeep Arora. "Surface Solid Dispersion – A Review." International Journal of Pharmaceutical Sciences and Nanotechnology 6, no. 1 (May 31, 2013): 1915–25. http://dx.doi.org/10.37285/ijpsn.2013.6.1.1.
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Preparation of an effective formulation of poorly water-soluble drugs is a key challenge in pharmaceutical technology. Dissolution rate and solubility are the rate- limiting steps for increasing the bioavailability of poorly water‐soluble drugs. Solid dispersion is an efficient technique for improving dissolution rate and subsequently, the bioavailability of poorly water‐soluble drugs. Surface sSolid dDispersion is a novel technique of solid dispersion for dispersing one or more active ingredients on a water insoluble carrier of high surface area in order to achieve increased dissolution rates and bioavailability of insoluble drugs. The Vvarious polymers used in this technique are Avicel, Crosspovidone, sSodium starch glycolate, pPregelatinized starch, Cab-o-sil, Ac-di-sol, KyronT-314, Primojel and pPotato sStarch. This article reviews the various methods of preparation and characterization of surface solid dispersion and compiles some of the drugs formulated as surface solid dispersions. Some of the practical aspects to be considered for preparing surface solid dispersion are selection of a suitable carrier and method of preparation of surface solid dispersion.
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Ben Basat, Moran, and Noa Lachman. "Development of Quality Control Methods for Dispersibility and Stability of Single-Wall Carbon Nanotubes in an Aqueous Medium." Nanomaterials 11, no. 10 (October 5, 2021): 2618. http://dx.doi.org/10.3390/nano11102618.
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The attractive properties of single-wall carbon nanotubes (SWCNT) such as mechanical strength and high electrical and thermal conductivity are often undercut by their agglomeration and re-agglomeration tendencies. As a result, the application of SWCNT as additives in advanced composite materials remain far from their potential, with proper dispersion being the major inhibitor. This work presents a dispersion quality control approach for water-based SWCNT dispersions (dispersed by a unique combination of physical and chemical methods), using complementary and easily scalable, characterization methods. UV-Vis spectroscopy, rheological measurements, and precipitant sheet resistance were used to understand the properties of the initial solution through processing and application. From an industrial perspective, these methods are fast and easy to measure while giving a repetitive and quick indication of dispersion quality and stability. The methods were correlated with microscopy and Raman spectroscopy to validate dispersion and SWCNT quality under various dispersing energies. The protocol was then applied to estimate the stability of SWCNT solutions, as well as the effectiveness of different surfactants in aiding dispersion. The simple, fast, and scalable combination of different characterizations provides good SWCNT dispersion and can be used as a quality control system for industrial production and usage.
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Perumal, Suguna, Raji Atchudan, and In Woo Cheong. "Recent Studies on Dispersion of Graphene–Polymer Composites." Polymers 13, no. 14 (July 20, 2021): 2375. http://dx.doi.org/10.3390/polym13142375.
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Graphene is an excellent 2D material that has extraordinary properties such as high surface area, electron mobility, conductivity, and high light transmission. Polymer composites are used in many applications in place of polymers. In recent years, the development of stable graphene dispersions with high graphene concentrations has attracted great attention due to their applications in energy, bio-fields, and so forth. Thus, this review essentially discusses the preparation of stable graphene–polymer composites/dispersions. Discussion on existing methods of preparing graphene is included with their merits and demerits. Among existing methods, mechanical exfoliation is widely used for the preparation of stable graphene dispersion, the theoretical background of this method is discussed briefly. Solvents, surfactants, and polymers that are used for dispersing graphene and the factors to be considered while preparing stable graphene dispersions are discussed in detail. Further, the direct applications of stable graphene dispersions are discussed briefly. Finally, a summary and prospects for the development of stable graphene dispersions are proposed.
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Erol, Özlem. "Electric Field Responsive Smart Fluids from Olive Pulp Powder." Süleyman Demirel Üniversitesi Fen Edebiyat Fakültesi Fen Dergisi 19, no. 2 (August 12, 2024): 127–43. http://dx.doi.org/10.29233/sdufeffd.1451712.
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This study aims to evaluate one of the wastes of the olive oil industry, olive pulp powder (OP), due to its consisting of mainly polarizable lignocellulosic biomass, as a dispersed phase in electric field-responsive (ER) fluid whose rheological properties can be tuned by an externally applied electric field (E). The supplied OP was extracted with n-hexane, and structural and thermal analysis revealed the removal of residual oil and soluble small molecules. The OP and n-hexane treated-OP (h-OP) were dispersed in silicon oil (SO), and their rheological and dielectric properties, and dispersion stabilities were investigated. According to the flow test results, the yield stresses (τy) of both dispersions increased with increasing concentration and the E. The τy of the OP/SO and h-OP/SO dispersions (25 wt%) under E=3.5 kV/mm increased 29 and 130 times greater than their τy values under no E, respectively. The dielectric spectrum analysis showed that enhanced interfacial polarization and decreased nonpolarized forces after the n-hexane extraction improved the ER response of the h-OP/SO dispersion. The enhanced dispersion stability (90%) was determined for h-OP/SO dispersion at 25 wt%. As a result, the h-OP could be a sustainable candidate for evaluation as a dispersing phase of ER fluids for vibration-damping systems.
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Borja, Katerine, Jaime Mercado, and Enrique Combatt. "Methods of mechanical dispersion for determining granulometric fractions in soils using four dispersant solutions." Agronomía Colombiana 33, no. 2 (May 1, 2015): 253–60. http://dx.doi.org/10.15446/agron.colomb.v33n2.47236.
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Sieve analysis studies depend on obtaining suspensions of fully-dispersed and stable samples to facilitate the quantification of the fractions of soil aggregates. The aim of this study was to compare the percentage of fractions obtained with four chemical dispersants and two methods of mechanical dispersion. To carry out this investigation, nine soils were selected from the departments of Cordoba and Sucre and four methodologies using chemical dispersions: ((NaPO3)6 + Na2CO3), (NaOH) 1M, (Na4P2O7) 0.1M pH 10, and CH3COONa 1M, and two methodologies of mechanical dispersion were evaluated: a slow one at 60 rpm for 6 hours and another at 4,000 rpm for 15 minutes. The results were analyzed using a correlation test and contrasts. It was verified that the highest content of clay in the soil samples was found when using the 60 rpm agitation methodology, due to greater dispersion of the granulometric fractions. Likewise, when comparing the different methods of chemical dispersion, it was determined that NaOH had the highest dispersing ability and sodium acetate presented a low efficiency in the separation of soil particles.
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Jin, J., W. Kaewsakul, J. W. M. Noordermeer, W. K. Dierkes, and A. Blume. "MACRO- AND MICRO-DISPERSION OF SILICA IN TIRE TREAD COMPOUNDS: ARE THEY RELATED?" Rubber Chemistry and Technology 94, no. 2 (April 1, 2021): 355–75. http://dx.doi.org/10.5254/rct.20.80365.
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ABSTRACT The dispersion of rubber fillers, such as silica, can be divided into two categories: macro- and micro-dispersion. Both dispersions are important; however, to achieve the best reinforcement of rubber, micro-dispersion of silica is crucial. The common view is that these filler dispersions are strongly related. The micro-dispersion is understood as the consequence of the continuous breakdown of filler clusters from macro-dispersion. Yet, a large problem is that an objective unequivocal direct measurement method for micro-dispersion is not available. In this study, a set of parameters is defined that are anticipated to have an influence on the micro- as well as the macro-dispersion. Mixing trials are performed with varying silanization temperature and time, different amounts of silane coupling agent, and by using silicas with different structures and specific surface areas. The degrees of micro- and macro-dispersion are evaluated by measuring the Payne effect as an indirect method for micro-dispersion and using a dispergrader for quantitative measurement of macro-dispersion. The results show that the filler dispersion processes happen simultaneously but independently. These results are supported by earlier work of Blume and Uhrlandt, who stated as well that micro- and macro-dispersion are independent. The major influencing factors on micro- and macro-dispersion of silica are also identified.
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Ramos, Héctor M., and Miguel A. Sordo. "Dispersion measures and dispersive orderings." Statistics & Probability Letters 61, no. 2 (January 2003): 123–31. http://dx.doi.org/10.1016/s0167-7152(02)00341-3.
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Gholamian, Hossein, Maksym Loginov, Marie-Hélène Famelart, Florence Rousseau, Fabienne Garnier-Lambrouin, and Geneviève Gésan-Guiziou. "Component Distribution, Shear-Flow Behavior, and Sol–Gel Transition in Mixed Dispersions of Casein Micelles and Serum Proteins." Foods 13, no. 21 (October 30, 2024): 3480. http://dx.doi.org/10.3390/foods13213480.
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The shear flow and solid–liquid transition of mixed milk protein dispersions with varying concentrations of casein micelles (CMs) and serum proteins (SPs) are integral to key dairy processing operations, including microfiltration, ultrafiltration, diafiltration, and concentration–evaporation. However, the rheological behavior of these dispersions has not been sufficiently studied. In the present work, dispersions of CMs and SPs with total protein weight fractions (ωPR) of 0.021–0.28 and SP to total protein weight ratios (RSP) of 0.066–0.214 and 1 were prepared by dispersing the respective protein isolates in the permeate from skim milk ultrafiltration and then further concentrated via osmotic compression. The partition of SPs between the CMs and the dispersion medium was assessed by measuring the dry matter content and viscosity of the dispersion medium after separating it from the CMs via ultracentrifugation. The rheological properties were studied at 20 °C via shear rheometry, and the sol–gel transition was characterized via oscillatory measurements. No absorption of SPs by CMs was observed in dispersions with ωPR = 0.083–0.126, regardless of the RSP. For dispersions of SPs with ωPR ≤ 0.21, as well as the dispersion medium of mixed dispersions with ωPR = 0.083–0.126, the high shear- rate-limiting viscosity was described using Lee’s equation with an SP voluminosity (vSP) of 2.09 mL·g−1. For the mixed dispersions with a CM volume fraction of φCM ≤ 0.37, the relative high shear-rate-limiting viscosity was described using Lee’s equation with a CM voluminosity (vCM) of 4.15 mL·g−1 and a vSP of 2.09 mL·g−1, regardless of the RSP. For the mixed dispersions with φCM > 0.55, the relative viscosity increased significantly with an increasing RSP (this was explained by an increase in repulsion between CMs). However, the sol–gel transition was independent of the RSP and was observed at φCM ≈ 0.65.
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Opaynych, Iryna Ye, and Zenovii M. Yaremko. "Aqueous Dispersions of High-dispersion Polystyrene." NIP & Digital Fabrication Conference 21, no. 1 (January 1, 2005): 628. http://dx.doi.org/10.2352/issn.2169-4451.2005.21.1.art00075_2.
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Safronova, Ekaterina Yu, Daria Yu Voropaeva, Dmitry V. Safronov, Nastasia Stretton, Anna V. Parshina, and Andrey B. Yaroslavtsev. "Correlation between Nafion Morphology in Various Dispersion Liquids and Properties of the Cast Membranes." Membranes 13, no. 1 (December 22, 2022): 13. http://dx.doi.org/10.3390/membranes13010013.
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Nafion is a perfluorosulfonic acid polymer that is most commonly used in proton-exchange membrane fuel cells. The processes of pretreatment and formation of such membranes strongly affect their properties. In this work, dispersions of Nafion in various ionic forms and dispersing liquids (ethylene glycol, N,N-dimethylformamide, N-methyl-2-pyrrolidone and isopropyl alcohol–water mixtures in different ratios) were obtained and studied. Membranes fabricated by casting of the various dispersions were also studied. The effect of the nature of the dispersing liquid and the counterion on the properties of Nafion dispersions, the morphology of the polymer in the dispersions and the characteristics of the membranes obtained from them has been shown. Based on the overall results, it can be concluded that the use of perfluorosulfonic acid dispersions in aprotic polar solvents is advisable for obtaining membranes by the casting procedure. This is because it provides optimal polymer morphology in the dispersion, which leads to the formation of films with good selectivity, mechanical and transport properties. The performed investigations show the relationship between the composition of dispersions, the morphology of the polymer and the properties of the membranes formed from them by the casting procedure.
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Marcondes, C. G. N., and M. H. F. Medeiros. "Análisis de la dispersión de soluciones conteniendo nanotubos de carbono para su uso en concretos de Cemento Portland." Revista ALCONPAT 6, no. 2 (May 31, 2016): 84–100. http://dx.doi.org/10.21041/ra.v6i2.131.
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Análisis de la dispersión de soluciones conteniendo nanotubos de carbono para su uso en concretos de Cemento PortlandRESUMENLos nanotubos de carbono (NTC) son estructuras nanométricas de carbono en formas cilíndricas. Para su uso en hormigón, una de las dificultades es su dispersión, enfoque de este trabajo. Se utilizó una herramienta conocida como análisis jerárquico para investigar la eficiencia de dispersión de los NTC en el agua de la mezcla de hormigón. Fueron estudiados 12 maneras de dispersiones en medio acuoso que contiene diferentes productos químicos. Se usaron los nanotubos de carbono de pared múltiple en forma de polvo y los ya procesados, dispersos en agua. El estudio mostró que la herramienta de análisis jerárquico podría constituir una alternativa eficaz para la elección de una mejor dispersión, teniendo en cuenta los factores que influyen en forma sistémica.Palabras clave: Proceso de análisis jerárquico; hormigón; nanotubos de carbón. Analyzing the dispersion of carbon nanotubes solution for use in Portland cement concreteABSTRACTCarbon nanotubes (CNTs) are nanometric carbon structures with cylindrical formats. For use in concretes, one of the difficulties is in its dispersion, focus this work. It used a tool known as hierarchical analysis to investigate the efficiency of the dispersion of carbon nanotubes in concrete kneading water. Were studied 12 forms of dispersions in aqueous medium containing hum Miscellaneous Chemicals. Carbon nanotubes multi-walled in powder form and Processed already dispersed in water were used. The study showed that the hierarchical analysis tool might constitute an alternative to the election of the best choice among the available options, considering the factors of influence in a systemic way.Keywords: Analytical hierarchy process; concrete; carbon nanotubes. Análise da dispersão de soluções contendo nanotubos de carbono para uso em concretos de Cimento PortlandRESUMOOs nanotubos de carbono (NTC) são estruturas nanometricas de carbono com formatos cilindricos. Para uso em concretos, uma das dificuldades está na sua dispersão, foco deste trabalho. Foi usada uma ferramenta conhecida como análise hierárquica. Para investigar a eficiência da dispersão dos nanotubos de carbono na água de amassamento do concreto, foram estudados 12 formas de dispersões em um meio aquoso contendo diversos produtos químicos. Foram utilizados os nanotubos de carbono de paredes múltiplas em forma de pó e os industrializados, já dispersos em água. O trabalho demonstrou que a ferramenta de análise hierárquica poderia se constituir em uma alternativa eficiente para a eleição da melhor dispersão, considerando os fatores de influência de forma sistêmica.Palavras-chave: Análise Hierárquica; concreto; nanotubos de carbono.
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Sohn, Jubee, Margaret J. Geller, Josh Borrow, and Mark Vogelsberger. "Velocity Dispersions of Quiescent Galaxies in IllustrisTNG." Astrophysical Journal 964, no. 2 (March 29, 2024): 178. http://dx.doi.org/10.3847/1538-4357/ad2c0a.
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Abstract We examine the central stellar velocity dispersion of subhalos based on IllustrisTNG cosmological hydrodynamic simulations. The central velocity dispersion is a fundamental observable that links galaxies with their dark matter subhalos. We carefully explore simulated stellar velocity dispersions derived with different definitions to assess possible systematics. We explore the impact of variation in the identification of member stellar particles, the viewing axes, the velocity dispersion computation technique, and simulation resolution. None of these issues impact the velocity dispersion significantly; any systematic uncertainties are smaller than the random error. We examine the stellar mass–velocity dispersion relation as an observational test of the simulations. At fixed stellar mass, the observed velocity dispersions significantly exceed the simulation results. This discrepancy is an interesting benchmark for the IllustrisTNG simulations because the simulations are not explicitly tuned to match this relation. We demonstrate that the stellar velocity dispersion provides measures of the dark matter velocity dispersion and the dark matter subhalo mass.
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Meng, Jin Feng, Jia Guang Meng, Lin Mei Zhang, and Ling Ling Ding. "Dispersion of Nano Self-Cleaning Finishing Agents about Suit Fabric." Materials Science Forum 852 (April 2016): 356–61. http://dx.doi.org/10.4028/www.scientific.net/msf.852.356.
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A practical nanopowders dispersion process is designed in order to solve self-cleaning finishing agent reunion.Seven kinds of typical dispersing agent are used for dispersing nanopowders. nanoTiO2-doped ZnO composite powders are chosed as raw material, polysodium acrylate as dispersant, nanopowders are effectively dispersed to get a self-cleaning finishing agent with a uniform dispersion, the average particle size at about 30-40 nm . By orthogonal test, optimum dispersion process conditions were: nanoTiO2 / ZnO powders 1 g / L, polysodium acrylate dispersant 1 g / L, dispersion methods were shear emulsification dispersion method and ultrasonic dispersion method,nanosample stirring time 10min, high shear revolutions 3500r / min, high shearing time 30min, ultrasonic time 5min, ultrasonic power 1 000w.
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Malkawi, Ruba, Walla I. Malkawi, Yahia Al-Mahmoud, and Jawad Tawalbeh. "Current Trends on Solid Dispersions: Past, Present, and Future." Advances in Pharmacological and Pharmaceutical Sciences 2022 (October 22, 2022): 1–17. http://dx.doi.org/10.1155/2022/5916013.
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Solid dispersions have achieved significant interest as an effective means of enhancing the dissolution rate and thus the bioavailability of a range of weakly water-soluble drugs. Solid dispersions of weakly water-soluble drugs with water-soluble carriers have lowered the frequency of these problems and improved dissolution. Solid dispersion is a solubilization technology emphasizing mainly on, drug-polymer two-component systems in which drug dispersion and its stabilization is the key to formulation development. Therefore, this technology is recognized as an exceptionally useful means of improving the dissolution properties of poorly water-soluble drugs and in the latest years, a big deal of understanding has been accumulated about solid dispersion, however, their commercial application is limited. In this review article, emphasis is placed on solubility, BCS classification, and carriers. Moreover, this article presents the diverse preparation techniques for solid dispersion and gathers some of the recent technological transfers. The different types of solid dispersions based on the carrier used and molecular arrangement were underlined. Additionally, it summarizes the mechanisms, the methods of preparing solid dispersions, and the marketed drugs that are available using solid dispersion approaches.
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Montazeri, Arash, Alireza Khavandi, Jafar Javadpour, and Abbas Tcharkhtchi. "An Investigation on the Effect of Sonication Time and Dispersing Medium on the Mechanical Properties of MWCNT/Epoxy Nanocomposites." Advanced Materials Research 264-265 (June 2011): 1954–59. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1954.
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This work studied the effect of sonication time and dispersing medium on the dispersion state of 0.1%wt multi-wall carbon nanotube (MWCNT) in the MWCNT/epoxy nanocomposite system. Epoxy, hardener, and epoxy/solvent were used as dispersing mediums in this study. Tensile strength, strain at failure, Young's modulus and fracture toughness were measured under different dispersion state of MWCNT. The results indicate that with the increase in sonication time, initially there was an increase in tensile strength and fracture toughness values which was followed by a drop in values at longer sonication times. The highest Young's modulus values were seen in epoxy dispersion and the highest tensile strength and fracture toughness values were observed when the hardener was used as dispersing medium. The results also indicated that the effect of sonication time was more pronounced in the case of epoxy dispersion. The effect of time was least when the epoxy / solvent system was used as CNT dispersing medium. It should also be pointed out that the Young's modulus for the nanocomposite sample obtained after 1h of dispersion in hardener showed good agreement with a modified Halpin-Tsai theory. The scanning electron microscope (SEM) was used to characterize the dispersion state of MWCNT. A good dispersion was obtained when either hardener or solvent were selected as the dispersing medium.
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Tran, Phuong H. L., Wei Duan, Beom-Jin Lee, and Thao T. D. Tran. "Modulation of Drug Crystallization and Molecular Interactions by Additives in Solid Dispersions for Improving Drug Bioavailability." Current Pharmaceutical Design 25, no. 18 (September 5, 2019): 2099–107. http://dx.doi.org/10.2174/1381612825666190618102717.
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Background:: An increase in poorly water-soluble drugs makes the design of drug delivery systems challenging. Methods:: Currently, a number of prospective solid dispersions have been investigated with potential applications for delivering a variety of poorly water-soluble drugs. A number of traditional solid dispersions and modifiedsolid dispersions offer attractive advantages in the fabrication, design and development of those drugs for effective therapeutics. Results:: Although traditional solid dispersions can produce a higher release rate, resulting in higher bioavailability compared to conventional dosage forms, this method is not always a promising approach. Modified-solid dispersion has demonstrated both the ability of its polymers to transform drug crystals into amorphous forms and molecular interactivity, thereby improving drug dissolution rate and bioavailability, especially with tough drugs. However, the classification of modified-solid dispersion, which guides the selection of the right strategy in solid dispersion preparation, remains ill-defined. Conclusions:: This review focused on effective strategies in using additives in solid dispersion for improving drug bioavailability.
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Vaishnavi Jadhav, Pooja Kashid, Kishor Otari, and Mohini Yadav. "Solubility Enhancement by Solid Dispersion Method: An Overview." Asian Journal of Pharmaceutical Research and Development 12, no. 4 (August 15, 2024): 113–18. http://dx.doi.org/10.22270/ajprd.v12i4.1450.
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To improve dissolution of poorly water-soluble drugs and thus enhancing their bioavailability, the dispersion of one or moreactive pharmaceutical ingredient in a carrier at solid state is used. This process is known as solid dispersion. It has engrossed significant interest as an efficient means of improving the dissolution rate. It happens due to dispersions of poorly water-soluble drugs with water-soluble carriers. The one of the most challenging aspects in formulation development is solubility behaviour of drugs. The number of poor water-soluble compounds has radically increased. Compared to conventional formulations such as tablets or capsules, solid dispersions prepared by various methods can be used which have many benefits over the above conventional dosage form. For the preparation of solid dispersions, few of the aspects are to be considered such as; selection of carrier and methods of physicochemical characterization. In this review, an emphasis is put on solubility, various types of solid dispersions, BCS classification, carriers, solid dispersion techniques, mechanism to enhance dissolution in solid dispersion, characterization, advantages, disadvantages and the application of the solid dispersions.
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Shin, Jaeman J. "Molecular Characterization of PFSA Ionomer Dispersions and Their Aggregated Structures." ECS Meeting Abstracts MA2024-02, no. 43 (November 22, 2024): 2901. https://doi.org/10.1149/ma2024-02432901mtgabs.
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Perflurosulfonic acid (PFSA) ionomers are widely used in numerous polymer electrolyte-based electrochemical devices including fuel cells and water electrolyzers. The majority of the state-of-the-art PFSA ionomers consist of chemically robust hydrophobic perfluorocarbon backbone and vinyl ether side chains terminated with hydrophilic sulfonic acid groups, which are highly incompatible. Therefore, such architecture allows hydrophobic-hydrophilic microphase-separated morphologies in a membrane to induce fast proton conduction. However, dispersion-cast ionomers cannot necessarily offer good performance over long periods, and thus it is important to understand the ionomer dispersion in molecular scale as well as aggregated state to correlate the dispersion characteristic with the performance of final dispersion-cast membrane film. Here, we investigate the physical characteristics of PFSA ionomer dispersions, with a particular focus on the molecular weight of ionomers. A series of commercial ionomers with various compositions were obtained and characterized in terms of equivalent weight (EW) and melt flow index (MFI). Ionomer dispersion was produced by screening various aqueous/alcohol and polar solvents with varying concentrations dispersing temperature, to achieve nanodispersion with an aggregate diameter being smaller than 20 nm, as confirmed by the light scattering measurement. Furthermore, size-exclusion chromatography (SEC) of ionomers was performed to determine the molar mass distribution of ionomers, in addition to providing information on the aggregation number of ionomer chains in the dispersion state. Additional characterization of the ionomer dispersion with multiangle light scattering (MALS) provided an estimate of the absolute molar mass of the ionomers, which implements the possible inaccuracy of the molecular weight obtained from SEC arising from the ionomer-column interaction. Combining these results allows correlation between the hydrodynamic radius of ionomer dispersion as a function of molecular weight (or MFI) values. Moreover, ionomer nanodispersion was cast into membrane film for rheological and morphological characterization to further establish the correlate between the physical properties of ionomer dispersion and membrane.
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SAKATA, H., K. HOSOKAWA, and T. KATO. "MEASUREMENT OF DIELECTRIC DISPERSION IN MULTI-FERROIC TbMnO3." International Journal of Modern Physics B 21, no. 18n19 (July 30, 2007): 3425–28. http://dx.doi.org/10.1142/s0217979207044676.
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We measured the dielectric dispersion in multi-ferroic TbMnO 3. We observed two kinds of the dielectric dispersions. One dispersion showed the monotonous temperature dependence of the relaxation frequency across the ferroelectric transition temperature, Tc. This dispersion is thought to be originated from the localized charge. The other dispersion existed only near the Tc, attributed to the ferroelectric transition. We found the former dispersion enhanced its strength near Tc. This indicates that the localized charge couples with the electric moment which orders in the ferroelectric phase.
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Tang, Min, Yun Liang, and Jian Hu. "The Impact of Fiber Dispersion on Filtration and Tensile Properties of Glass Fiber Filter Paper." Journal of Engineered Fibers and Fabrics 11, no. 4 (December 2016): 155892501601100. http://dx.doi.org/10.1177/155892501601100401.
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Air quality control has become increasingly important in many industrial areas. Glass fiber filter paper is widely used for the collection of airborne particulate matter. Since glass fiber is fragile, fiber dispersion is believed to be important for controlling filter paper properties. In this paper, the impact of fiber dispersion on filtration performance and tensile properties was studied. Two types of glass fiber filter paper prepared from six different dispersing methods were used to analyze the impact of dispersion on filtration and tensile properties. Rotational viscosity was used to characterize the fiber dispersion process. Dispersing strength and time had no significant effect on filtration properties, namely the pressure drop, penetration and figure of merit. The fiber composition should be the determining factor of filtration properties. Dispersing strength and time had little effect on the virgin tensile strength of glass fiber paper, while the tensile strength retention after folding was highly affected by dispersion. It is suggested that fiber cutting should be reduced in the fiber dispersion process for higher tensile strength retention.
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Kolikov, Kiril Hristov, Dimo Donchev Hristozov, Radka Paskova Koleva, and Georgi Aleksandrov Krustev. "Model of Close Packing for Determination of the Major Characteristics of the Liquid Dispersions Components." Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/615236.
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We introduce a close packing model of the particles from the disperse phase of a liquid dispersion. With this model, we find the sediment volumes, the emergent, and the bound dispersion medium. We formulate a new approach for determining the equivalent radii of the particles from the sediment and the emergent (different from the Stokes method). We also describe an easy manner to apply algebraic method for determining the average volumetric mass densities of the ultimate sediment and emergent, as well as the free dispersion medium (without using any pycnometers or densitometers). The masses of the different components and the density of the dispersion phase in the investigated liquid dispersion are also determined by means of the established densities. We introduce for the first time a dimensionless scale for numeric characterization and therefore an index for predicting the sedimentation stability of liquid dispersions in case of straight and/or reverse sedimentation. We also find the quantity of the pure substance (without pouring out or drying) in the dispersion phase of the liquid dispersions.
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Truhlar, Donald G. "Dispersion Forces: Neither Fluctuating Nor Dispersing." Journal of Chemical Education 96, no. 8 (July 18, 2019): 1671–75. http://dx.doi.org/10.1021/acs.jchemed.8b01044.
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Rahayu, Feronika Evma, Annysa Ellycornia Silvyana, Lia Warti, Salman Umar, and Henni Rosaini. "Solid Dispersion System Candesartan-cilexetil Mannitol Co-Grinding Method." PHARMACY: Jurnal Farmasi Indonesia (Pharmaceutical Journal of Indonesia) 20, no. 1 (July 31, 2023): 83. http://dx.doi.org/10.30595/pharmacy.v0i0.16667.
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Research on solid dispersion systems had been done to improve physicochemical characteristics and the dissolution rate of candesartan-cilexetil a had been conducted. Candesartan cilexetil is included in BCS (Biopharmaceutical Classification System) class II, which has low solubility and high permeability which causes poor absorption of drugs in the digestive tract. Solid dispersions were prepared through the grinding method using mannitol. The formula with 3 comparisons between candesartan-cilexetil and mannitol 1:1, 1:3, and 1:5. A mixture of physics of candesartan cilexetil-mannitol was made without a solid dispersions system which was 1:1 as a comparison. Solid dispersion formed was characterized by particle size distribution analysis, Fourier transforms infrared (FT-IR), X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), determination rate, and dissolution test. The result particle size distribution analysis showed grinding method there were solid dispersions mixed perfectly. The FT-IR of this analysis showed no interaction between candesartan-cilexetil mannitol in solid dispersion powder. The result of X-ray diffraction showed a decrease in crystallization degree. The DSC result showed a shift in endothermic peak candesartan-cilexetil. The manufacture of a solid dispersion system of candesartan-cilexetil mannitol can improve the physicochemical characteristics and the dissolution rate of candesartan-cilexetil compared with physical mixtures. The result in the dissolution was solid dispersion 1 = 53.1990 %, solid dispersion 2 = 54.3621 %, and solid dispersion 3 = 62.3621 %. The statistical result of dissolution efficiency using the Kruskal-Willis test with significant = 0.009(< 0.05) showed the difference among the dissolution efficiency of candesartan-cilexetil, physical mixture, and each solid dispersion.
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R Kumari, P Chandel, and A Kapoor. "Paramount Role of Solid Dispersion in Enhancement of Solubility." Indo Global Journal of Pharmaceutical Sciences 03, no. 01 (2013): 78–89. http://dx.doi.org/10.35652/igjps.2013.10.
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One of the favorable strategy to improve the solubility and hence bioavailability of poorly water soluble drugs is the formulation of solid dispersion. It refers to dispersion of an active ingredient in a carrier at solid state which is prepared by solvent evaporation method, melting method, melt solvent method, kneading method, co-grinding method, co-precipitation method, modified solvent evaporation method, spray drying, gel entrapment technique, and co-precipitation with supercritical fluid. On the basis of the carrier used in solid dispersion it is classified as first, second and third generation solid dispersions. As per biopharmaceutical classification system class II drugs are with low solubility and high permeability and are the promising candidates for improvement of bioavailability by solid dispersion. Some of the practical aspects to be considered for the preparation of solid dispersions, such as selection of carrier, molecular arrangement of drugs in solid dispersions are discussed in this article. © 2011 IGJPS. All rights reserved.
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Lobo, Lloyd, Ivan Ivanov, and Darsh Wasan. "Dispersion coalescence: Kinetic stability of creamed dispersions." AIChE Journal 39, no. 2 (February 1993): 322–34. http://dx.doi.org/10.1002/aic.690390212.
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Gupta, Harshit, and John Texter. "Stimuli‐Responsive Polyurethane Dispersions – Aqueous Auto‐Dispersion." Israel Journal of Chemistry 58, no. 12 (October 25, 2018): 1338–46. http://dx.doi.org/10.1002/ijch.201800034.
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Stehlík, Michal. "INFLUENCE OF THE AGE OF EPOXY DISPERSION ON THE EFFECTIVENESS OF PROTECTION OF CONCRETE SURFACES." Engineering Structures and Technologies 4, no. 2 (June 26, 2012): 37–44. http://dx.doi.org/10.3846/2029882x.2012.697538.
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The scope of this paper is to test stability and mechanical and chemical properties of a modern freshly mixed epoxy dispersion, and as a variant, of a dispersion which is two years old. During ageing, the dispersion particles probably agglomerate, which is tested by laser diffraction and by sedimentation in a cylinder. Physical-mechanical tests assess the appearance, drying speed and mechanical properties of the film. Chemical tests focus on assessing the resistance of films of dispersions of different ages to common chemicals and to chemical defrosting agents. It is possible to say that two years of dispersion storage lead to a considerable increase in the diameter of a certain number of dispersion particles with the subsequent effect of increasing the sedimentation speed. The hardened film of a two-year old dispersion dries faster, has a rougher surface, is softer, but on the other hand, is less elastic and its adhesive capacity to the substrate is worse. Its chemical resistance is decreased but its defrosting agent resistance remains good. Due to the two-year storage of the epoxy dispersion, most of the monitored parameters decrease, nevertheless, certain protection of concrete structures by a hardened film of such epoxy dispersions is possible.
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Howlader, Md Sariful Islam, Jayanta Kishor Chakrabarty, Khandokar Sadique Faisal, Uttom Kumar, Md Raihan Sarkar, and Mohammad Firuz Khan. "Enhancing dissolution profile of diazepam using hydrophilic polymers by solid dispersion technique." International Current Pharmaceutical Journal 1, no. 12 (November 1, 2012): 423–30. http://dx.doi.org/10.3329/icpj.v1i12.12453.
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The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug by a solid dispersion technique, in order to investigate the effect of these polymers on release mechanism from solid dispersions. Diazepam was used as a model drug to evaluate its release characteristics from different matrices. Solid dispersions were prepared by using polyethylene glycol 6000 (PEG-6000), HPMC, HPC and Poloxamer in different drug-to-carrier ratios (1:2, 1:4, 1:6, 1:8, 1:10). The solid dispersions were prepared by solvent method. The pure drug and solid dispersions were characterized by in vitro dissolution study. Distilled water was used as dissolution media, 1000 ml of distilled water was used as dissolution medium in each dissolution basket at a temperature of 37°C and a paddle speed of 100 rpm. The very slow dissolution rate was observed for pure Diazepam and the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. SEM (Scanning Electron microscope) studies shows that the solid dispersion having a uniform dispersion. Solid dispersions prepared with PEG-6000, Poloxamer showed the highest improvement in wettability and dissolution rate of Diazepam. Solid dispersion containing polymer prepared with solvent method showed significant improvement in the release profile as compared to pure drug, Diazepam.DOI: http://dx.doi.org/10.3329/icpj.v1i12.12453 International Current Pharmaceutical Journal 2012, 1(12): 423-430
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Lee, Jeong Gyun, Su Min Lee, Seo Wan Yun, and Kyeong Soo Kim. "Development of Enzalutamide Solid Dispersion Loaded Tablet with Enhanced Solubility." Yakhak Hoeji 66, no. 5 (October 31, 2022): 283–91. http://dx.doi.org/10.17480/psk.2022.66.5.283.
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The objective of this study was to develop a novel enzalutamide tablet formulation with enhanced solubility and bioavailability, and inhibited recrystallization. Kollidon VA64 was selected as a soluble polymer for preparing enzalutamide solid dispersions. Solid dispersions with different enzalutamide to Kollidon VA64 weight ratios were prepared via solvent evaporation method. The enzalutamide solid dispersion consisting of enzalutamide and Kollidon VA64 at a weight ratio of 1:1, exhibited an excellent dissolution rate and potent inhibition of recrystallization. Enzalutamide solid dispersions were characterized by scanning electron microscopy, powder X-ray diffractometry, differential scanning calorimetry, and in vitro dissolution studies. The 1:1 solid dispersion exhibited excellent productivity, an elevated dissolution rate, and recrystallization inhibition. Therefore, enzalutamide solid dispersion loaded tablets were prepared and their dissolution was evaluated compared to a commercial product (Xtandi® soft capsule). The selected tablet formulation containing enzalutamide solid dispersion exhibited a higher dissolution rate in pH 1.0 solution than did the Xtandi® soft capsule, and prevented recrystallization of the enzalutamide. This research suggests that enzalutamide-containing solid dispersion tablets could be the most effective method to date for improving the dosing compliance of Xtandi® soft capsules, improving the dissolution rate of enzalutamide, and preventing recrystallization.
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Fitriani, Lili, Sherly Ramadhani, and Erizal Zaini. "PREPARATION AND CHARACTERIZATION OF SOLID DISPERSION FAMOTIDINE – MANNITOL BY CO-GRINDING METHOD." Asian Journal of Pharmaceutical and Clinical Research 10, no. 3 (March 1, 2017): 249. http://dx.doi.org/10.22159/ajpcr.2017.v10i3.16112.
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ABSTRACTObjective: This study aims to prepare and characterize solid dispersion of famotidine using mannitol to enhance the solubility and dissolution rate.Methods: Solid dispersions were prepared by co-grinding method in 9 formulas. The ratio of famotidine and mannitol was varied (1:1, 1:2, 2:1 w/w),and each ratio was milled at three different times (30, 60, and 90 minutes). The physical mixture was also prepared as comparison at ratio 1:1 w/w.Solid dispersions were characterized by X-ray diffraction analysis, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry(DSC) analysis, scanning electron microscopy (SEM), particle size analysis, solubility, and dissolution rate study. The assay of famotidine was doneusing a UV spectrophotometer.Results: The highest solubility of famotidine in solid dispersion was obtained in F2 (ratio 1:2 and grinding time 30 minutes). The solubility of intactfamotidine, physical mixture, and solid dispersion F2 was 1.630±0.027, 2.757±0.096, and 3.272±0.076 mg/ml, respectively. X-ray diffractogram ofsolid dispersion F2 showed a decrease in the peak intensity of famotidine. Thermogram of DSC showed a decrease of famotidine melting point for bothphysical mixture and solid dispersion. Photomicrograph of SEM indicated the changes in morphology solid dispersion compared to intact substances.FTIR analysis showed no chemical interaction between famotidine and mannitol. The particle size analysis showed a reduction in the particle sizeof the solid dispersion. The dissolution result after 60 minutes was 85.029%, 86.166%, 92.057% for intact famotidine, physical mixture, and soliddispersion F2, respectively.Conclusion: Solid dispersion increased solubility and dissolution rate.Keywords: Solid dispersion, Famotidine, Mannitol, Co-grinding, Solubility.
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Varma, Mohan M., and Satish Kumar P. "Formulation and Evaluation of Gliclazide Tablets Containing PVP-K30 and Hydroxypropyl-β-cyclodextrin Solid Dispersion." International Journal of Pharmaceutical Sciences and Nanotechnology 5, no. 2 (August 31, 2012): 1706–19. http://dx.doi.org/10.37285/ijpsn.2012.5.2.6.
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Gliclazide is an anti-diabetic drug. It is a BCS class-II (poorly water soluble) drug and its bioavailability is dissolution rate limited. The dissolution rate of the drug was enhanced by using the solid dispersion technique. Solid dispersions were prepared using PVP-K30 (polyvinylpyrrolidone) and hydroxypropyl-β-cyclodextrin (HP BCD) as the hydrophilic carriers. The solid dispersions were characterized by using DSC (Differential scanning calorimetry), XRD (X-ray diffractometry) and FTIR (Fourier transform infrared spectroscopy). Solid dispersions were formulated into tablets. The formulated tablets were evaluated for the quality control parameters and dissolution rates. The solid-dispersion tablets enhanced the dissolution rate of the poorly soluble drug. The optimized formulation showed a 3 fold faster drug release compared to the branded tablet. The XRD studies demonstrated the remarkable reduction in the crystallinity of the drug in the solid dispersion. The faster dissolution rate of the drug from the solid dispersion is attributed to the marked reduction in the crystallinity of the drug. The DSC and FTIR studies demonstrated the absence of the drug-polymer interaction.
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Prapti Desai, Nitin Deshmukh, Apeksha Rajguru, Rohini Khedkar, and Rahul Jadhav. "Formulation and evaluation of valsartan solid dispersion for improvement of dissolution profile." World Journal of Biology Pharmacy and Health Sciences 15, no. 2 (August 30, 2023): 208–24. http://dx.doi.org/10.30574/wjbphs.2023.15.2.0314.
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In terms of physicochemical factors, solubility is the most crucial to medication absorption and therapeutic efficacy. Bioavailability is low because the medicine is poorly soluble in water and is absorbed poorly in aqueous GIT fluid. In this research, a solid dispersion version of the hypertension drug valsartan was developed to improve its bioavailability and blood pressure-lowering effects. The solubility of Valsartan is improved by using the solid dispersion (kneading method) technique using Soluplus as a carrier (also act as taste masking agent). They were distinguished from one another based on studies examining solubility, in vitro dissolution, dissolving efficiency, and stability. X-ray diffraction, FT-IR spectroscopy, and differential scanning Calorimetry were used to investigate the solid state properties of dispersions (XRD). A 1:1 medication-to-polymer solid dispersion showed 97.77% drug release after 30 minutes. FTIR, DSC, and XRD analyses of solid dispersions all corroborated their formation. A DSC study shown that under accelerated climate settings, kneaded solid dispersion remained stable for 30 days longer than other solid dispersions.
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Bhide, Prashant, and Reeshwa Nachinolkar. "FORMULATION DEVELOPMENT AND CHARACTERISATION OF MECLIZINE HYDROCHLORIDE FAST DISSOLVING TABLETS USING SOLID DISPERSION TECHNIQUE." International Journal of Applied Pharmaceutics 10, no. 4 (July 7, 2018): 141. http://dx.doi.org/10.22159/ijap.2018v10i4.26493.
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Objective: The aim of the present investigation was to design and evaluate fast dissolving tablet (FDT) for the oral delivery containing solid dispersion of meclizine (MCZ) hydrochloride, an antiemetic drug.Methods: The solubility of meclizine was increased by preparing solid dispersions using mannitol as a carrier by fusion method. The prepared solid dispersion, was subjected for in vitro drug release, percent practical yield, drug content, infrared spectroscopy (IR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM). Optimized solid dispersion was incorporated to prepare fast dissolving tablets. Preformulation studies were carried out on tablet blends. The prepared solid dispersion, as well as pure drug fast dissolving tablets, was evaluated for drug content, weight variation, hardness, friability, in vitro drug release, wetting time, disintegration time, water absorption ratio, in vitro dispersion time.Results: Meclizine pure drug, solid dispersions formulations SD1, SD3 and SD5 showed 12.8, 31.68, 38.92 and 53.28% cumulative drug release in phosphate buffer pH 6.8 after 60 min, respectively. Thus faster dissolution rate was exhibited by the solid dispersion containing 1:5 (w/w) ratio of meclizine: mannitol. Percent cumulative drug release for control and solid dispersion tablets after 60 min in phosphate buffer pH 6.8 was 92.04 and 98.2% respectively. The release of drug meclizine from best formulation SD5 FDT was found to be faster than pure drug FDT.Conclusion: Fast dissolving tablet of optimized solid dispersion showed better in vitro dissolution result then FDT of pure drug at the end of one hour.
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Bachmann, Rüdiger, and Christian Bayer. "Investment Dispersion and the Business Cycle." American Economic Review 104, no. 4 (April 1, 2014): 1392–416. http://dx.doi.org/10.1257/aer.104.4.1392.
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The cross-sectional dispersion of firm-level investment rates is procyclical. This makes investment rates different from productivity, output, and employment growth, which have countercyclical dispersions. A calibrated heterogeneous-firm business cycle model with nonconvex capital adjustment costs and countercyclical dispersion of firm-level productivity shocks replicates these facts and produces a correlation between investment dispersion and aggregate output of 0.53, close to 0.45 in the data. We find that small shocks to the dispersion of productivity, which in the model constitutes firm risk, suffice to generate the mildly procyclical investment dispersion in the data but do not produce serious business cycles. (JEL D42, D92, E32, G31, G32)
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Mohammed, Ebtissam Ameer, Mohanad Alfahad, and Mohannad E. Qazzaz. "Solid dispersion: application and limitations." Journal of Drug Delivery and Therapeutics 14, no. 2 (February 15, 2024): 222–32. http://dx.doi.org/10.22270/jddt.v14i2.6410.
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Solubility and dissolution rate are essential factors in the bioavailability of a drug. The drug must be well-soluble in water to have good bioavailability. Solid dispersion is among the most widely used and effective methods for increasing solubility and releasing inadequately water-soluble medications. Solid dispersion requires the choice of a suitable carrier for the right active pharmaceutical ingredients and the proper techniques for preparing solid dispersions. The reliable dispersion system is designed in various ways to achieve the goal and avoid the accompanying obstacles.
Keywords: solid dispersion, solubility, solvent evaporation, lyophilization, generation, methods
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Mirza, Mohd Aamir. "Solubility Enhancement of Diclofenac Using Solid Dispersions." International Journal of Pharmaceutics & Pharmacology 5, no. 1 (June 30, 2021): 1–6. http://dx.doi.org/10.31531/2581-3080.1000154.
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Background: The phenomenon which gives rise to a homogenous system, formed by the dissolution of solute in a solvent is known as solubility. Low solubility is the limiting factor in formulation development. Diclofenac being BCS class II drug have low aqueous solubility of 0.00401mg/ml. Amongst various solubility enhancement techniques, solid dispersion is the easiest one. Objective: Present work is primarily focused on the development of solid dispersions of diclofenac through solvent evaporation technique utilizing Eudragit E100 as a carrier. Methods: Solid dispersion consists of at least one active pharmaceutical ingredient as a carrier in solid state. Various methods for preparing solid dispersions includes melt extrusion, fusion lyophilization, spray drying, solvent evaporation, and super critical fluid (SCF) technology. Solvent evaporation technique is used among various solid dispersion methods. Conclusion: The enhanced solubility found to be 0.485mg/ml. The dissolution was performed using USP Type II apparatus was %CDR of pure drug and its solid dispersion in 8 hr were found out to be 45.14926% and 98.04758% respectively. Henceforth, solid dispersion technique results marked solubility enhancement of diclofenac sodium.
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Kastsova A. G., Glebova N. V., Nechitailov A. A., Krasnova A.O., Pelageikina A.O., and Eliseyev I. A. "Electronic spectroscopy of graphene obtained by ultrasonic dispersion." Technical Physics Letters 48, no. 12 (2022): 60. http://dx.doi.org/10.21883/tpl.2022.12.54950.19268.
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A technology for obtaining graphene by means of ultrasonic dispersion of thermally expanded graphite in the presence of a surface-active polymer Nafion is presented. The technology makes it possible to obtain large amounts of low-layer (1-3 layers) graphene in a relatively short time. An approach to control the dispersion process based on UV spectroscopy of dispersions is described. A mechanism is proposed for the effect of a surface-active polymer on the production of low-layer graphene by ultrasonic dispersion. Keywords: graphene, ultrasonic dispersion, thermally expanded graphite.
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Dohnalová, Z., L. Svoboda, and P. Sulcová. "Characterization of kaolin dispersion using acoustic and electroacoustic spectroscopy." Journal of Mining and Metallurgy, Section B: Metallurgy 44, no. 1 (2008): 63–72. http://dx.doi.org/10.2298/jmmb0801063d.
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The objective of this work is the investigation of the kaolin dispersion by the ultrasonic techniques. In contact with aqueous solution clay minerals show cation - exchange properties and certain degree of dissolution or rather selective leaching of components. The work is divided into two main parts - determination of zeta potential and particle size distribution. The first part is focused on measuring of zeta potential. Effects of concentration of solid, different kind of electrolytes (0.01 M KCl, 0.01 M MgCl2 and 0.01 M CaCl2), pH and temperature of the dispersions are investigated. The isoelectric points (IEP) of kaolin suspension are about pH 4-5. Electrolytes containing monovalent cations such as K+ become zeta potential more negative compared to the values obtained with water. Such behavior is explained by the exchange of K+ ions with H+ ions in the system. When the electrolyte is formed by divalent cations such as Mg2+ or Ca2+, the values of zeta potential become less negative than zeta potential of kaolin in water. The second part is focused on the determination of particle size distribution with respect to dispersing conditions, such as the optimal dispersing agent (Na2SiO3, (NaPO3)6, Na4P2O7 or Busperse), time and power of ultrasonication and also the tracking of dispersion stability that is expressed by the measuring of particle size distribution during certain time period.
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Wang, Hui, Hong Xin Xu, Na Zhang, and Lian Dong Hu. "Enhancement of Dissolution Rate of Daidzein in Ternary Solid Dispersions." Advanced Materials Research 550-553 (July 2012): 1000–1004. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1000.
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The purpose of this study was to enhance the dissolution rate of daidzein (DZ) by solid dispersions. DZ solid dispersion was prepared by solvent method, with PVP K30 and surfactant as carriers. The influences of drug-carrier proportion, the kind of surfactant and the amount of surfactant on the dissolution of DZ were examined. Solid dispersions were characterized by infrared spectroscopy (IR), X-ray diffraction spectroscopy, and dissolution tests. When appropriate amount of poloxamer was added into the solid dispersion, the dissolution of DZ could be improved obviously. The data of IR showed that the absence of well-defined drug-polymer interactions. The data of X-ray diffraction showed that the drug might exist in the form of amorphism or molecule in solid dispersions. Both the binary and ternary solid dispersions enhanced the dissolution of DZ. Moreover, poloxamer played an important positive role in improving the dissolution rate of DZ in the solid dispersion.
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Zhang, Zijian, Yuanzhen Li, Chi Wang, Su Xu, Zuojia Wang, Erping Li, Hongsheng Chen, and Fei Gao. "Dispersion-tunable photonic topological waveguides." Applied Physics Letters 121, no. 1 (July 4, 2022): 011701. http://dx.doi.org/10.1063/5.0097422.
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Dispersion-tunable photonic topological waveguides have recently attracted much attention, due to their promising applications on topological devices with tunable operational frequencies. Since dispersions of topological waveguides traverse the whole bandgaps of bulk structures, tuning the dispersions (especially the bandwidths) requires changing the whole bulk of corresponding photonic topological insulators. A previously reported material-modification approach provided a parallel tuning on such numerous lattices; however, the increased material loss deteriorated transmissions of the topological waveguide. Here, a parallel tuning approach on structures is theoretically proposed and demonstrated, which spawns dispersion-tunable photonic topological waveguides without increasing material loss. Based on the bilayer honeycomb model, a topological valley waveguide by utilizing bilayer designer plasmonic structures is constructed, accomplished with dispersion tunings by altering interlayer distance. Experimental results validate the theoretical model and display a 61%-relative-tuning range of frequency, with a tunable relative bandwidth up to 16%. This approach may promise applications in tunable topological lasers, robust delay lines, and intelligent photonic devices.
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Balaji, Thirumaran, Dhasan Mohan Lal, and Chandrasekaran Selvam. "A Critical Review on the Thermal Transport Characteristics of Graphene-Based Nanofluids." Energies 16, no. 6 (March 12, 2023): 2663. http://dx.doi.org/10.3390/en16062663.
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Over the past few years, considerable research work has been performed on the graphene-based nano-dispersion for improvement of the thermal conductivity and thermal characteristics of base fluid. Graphene-based dispersion shows the good stability, better enhancement in thermal conductivity, and heat transport behavior compared to the other nano-dispersions drawing significant attention among researchers. This article carries out comprehensive reviews on the heat transport behavior of graphene-based nano-dispersion over the past ten years. Some researchers have carried out the investigations on the various methods adopted for the preparation of graphene-based nano-dispersion, techniques involved in making good dispersion including stability characterizations. There needs to be a better agreement in results reported by the various researchers, which paves the way for further potential research needs. Some researchers studied thermo-physical properties and heat transport behavior of graphene nanofluids. Only a few researchers have studied the usage of graphene nanofluids in various fields of application, including automobile radiators, electronics cooling, heat exchangers, etc. This article reviews the different challenges faced during its development in broad areas of application, and this could be a referral to have explicit knowledge of graphene dispersions with their characterization. Moreover, this study explores the various parameters that influence the effective thermal conductivity and heat transport behavior of the graphene dispersions for the various heat transport applications, which could be a reference guide to find the potential benefits as well as drawbacks of the graphene-based nano-dispersion for future research works.
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PATEL, MAHENDRA, ARPNA INDURKHYA, and MASHEER AHMED KHAN. "IMPROVEMENT OF DISSOLUTION RATE OF REPAGLINIDE BY UTILIZING SOLID DISPERSION TECHNIQUE." Current Research in Pharmaceutical Sciences 13, no. 1 (April 8, 2023): 78–82. http://dx.doi.org/10.24092/crps.2023.130107.
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The recent study's objective was to prepare and evaluate the Repaglinide (RG) solid dispersion. RG is poorly water soluble, BCS class II drug. Repaglinide solid dispersion (RG-SD) was prepared by solvent evaporation method using different proportion of PVP K30. The prepared RG-SD was evaluated for solubility studies, drug content, in vitro dissolution, DSC studies and XRD studies. DSC and XRD studies results indicate that RG exists in amorphous form in solid dispersion. The solubility of pure RG was enhanced from 34.41±0.68 to 370.3±1.52 μg/mL in distilled water at 370 C. RG-SD (RG:PVP K30) (1:10) showed high burst release (65%) in the first 30 min. Current research concludes that Repaglinide solid dispersions using PVP-K30 (1:10) as a carrier in solid dispersions showed promising results in enhancement of repaglinide properties. KEYWORDS: Repaglinide, Solid Dispersion, PVK K30, Dissolution Rate, Solvent evaporation
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Dong, Xia, Zhao He Zheng, and Jin Xin He. "Influence of Dye-Polyether Derivatives Architecture on Parent C. I. Disperse Yellow 64 Dispersion." Advanced Materials Research 79-82 (August 2009): 1931–34. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1931.
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Interface stability has been the subject of extensive investigation by the scientists working in the field of micron or nanometer materials for centuries and the control of the colloidal properties and stability of particle dispersions is of significant importance in the manufacture of high quality water-based dispersions or solvent-based systems. The waterborne dispersion of C.I. Disperse Yellow 64 requires the use of dispersant additives. By the reaction of C.I. Disperse Yellow 64 with poly(oxyalkylene)-amines, a series of dye-polyether derivatives, supposed to be used as dispersants for parent dye dispersions, was synthesized and subsequently characterized by amine titration, SEC and 1H NMR. The polyethers chosen are polyoxyethylene-polyoxypropylene diblock coploymers with different molecular weights and degrees of hydrophilicity/hydrophobicity in the backbones. The influence upon adsorption of dye-polyether derivatives on the dispersion behavior of parent C. I. Disperse Yellow 64 has been investigated. A range of experimental methods including adsorption isotherms, dispersion stability test, and particle size measurements were used to assess the dispersion effect of the dye-polyether derivatives. Adsorption of dye-polyether derivatives onto the parent dye surface is little affected by the molecular weight and increases with the increasing hydrophobicity of the polyether. The dispersion stability of the parent C.I. Disperse Yellow 64 dispersions has considerably been improved by the presence of all the dye-polyether derivatives. In particular, the dye-polyether derivatives exhibited excellent dispersive capacity for the dispersions even at a dye to dispersant weight ratio of 10:1, which largely reduced the dispersant demand compared with the commercial dye. This new strategy of the dye-polyether derivative as dispersant for its parent dye will result in significantly alleviating the environment pollution from dyeing effluent and is not only expected to be applicable to dispersion of other water-insoluble dyes in aqueous media, but also a new promising candidate for the stablization of micron or nanometer materials.
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Albornoz-Palma, Gregory, Daniel Ching, Andrea Andrade, Sergio Henríquez-Gallegos, Regis Teixeira Mendonça, and Miguel Pereira. "Relationships between Size Distribution, Morphological Characteristics, and Viscosity of Cellulose Nanofibril Dispersions." Polymers 14, no. 18 (September 14, 2022): 3843. http://dx.doi.org/10.3390/polym14183843.
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Rheological parameters of cellulose nanofibril dispersions (CNF) are relevant and commonly used as quality control for producing of this type of material. These parameters are affected by morphological features and size distribution of the nanofibrils. Understanding the effect of size distribution is essential for analyzing the rheological properties, viscosity control, performance of CNFs, and potential dispersion applications. This study aims at comprehending how the morphological characteristics of the CNFs and their size distribution affect the rheological behavior of dispersions. The CNF dispersions were fractionated by size, obtaining six fractions of each, which were analyzed for their morphology and rheology (viscosity, intrinsic viscosity). In the dilute region, the viscosity and intrinsic viscosity behavior of CNF dispersions are linear concerning the size distribution present in the dispersion. In the semi-dilute region, the size of the fibrils and the fiber aggregates have a relevant effect on the viscosity behavior of CNF dispersions, which are satisfactorily related (R2 = 0.997) using the rule of logarithmic additivity of the dispersion viscosities of size fractions.
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Fu, Boyan, Tianyue Li, Xiujuan Zou, Jianzheng Ren, Quan Yuan, Shuming Wang, Xun Cao, Zhenlin Wang, and Shining Zhu. "Steerable chromatic dispersive metalenses in dual bands." Journal of Physics D: Applied Physics 55, no. 25 (April 1, 2022): 255105. http://dx.doi.org/10.1088/1361-6463/ac59fb.
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Abstract As a promising flat optical element, metasurfaces possess the powerful ability to manipulate chromatic dispersion, resulting in achromatic imaging, ultracompact spectrometers, and wavelength-dependent multifunctional nano-devices. However, conventional chromatic metalenses are incapable of arbitrarily tailoring dispersion within different bandwidths. Here, with a supercell composed of two nanostructures, we can arbitrarily control the chromatic dispersion of the metalens by using the phase differential equation and genetic optimization. We design three metalenses to verify the simultaneous tailoring of different chromatic dispersions in dual bands, which exhibits stronger chromatic dispersion manipulation capability compared with a single-structure-cell-based metalens. Our approach paves a new way for dispersion engineering of metalenses with potential applications in spectral imaging and material analysis.
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Lizonova, Denisa, Una Trivanovic, Philip Demokritou, and Georgios A. Kelesidis. "Dispersion and Dosimetric Challenges of Hydrophobic Carbon-Based Nanoparticles in In Vitro Cellular Studies." Nanomaterials 14, no. 7 (March 27, 2024): 589. http://dx.doi.org/10.3390/nano14070589.
Full textAbstract:
Methodologies across the dispersion preparation, characterization, and cellular dosimetry of hydrophilic nanoparticles (NPs) have been developed and used extensively in the field of nanotoxicology. However, hydrophobic NPs pose a challenge for dispersion in aqueous culture media using conventional methods that include sonication followed by mixing in the culture medium of interest and cellular dosimetry. In this study, a robust methodology for the preparation of stable dispersions of hydrophobic NPs for cellular studies is developed by introducing continuous energy over time via stirring in the culture medium followed by dispersion characterization and cellular dosimetry. The stirring energy and the presence of proteins in the culture medium result in the formation of a protein corona around the NPs, stabilizing their dispersion, which can be used for in vitro cellular studies. The identification of the optimal stirring time is crucial for achieving dispersion and stability. This is assessed through a comprehensive stability testing protocol employing dynamic light scattering to evaluate the particle size distribution stability and polydispersity. Additionally, the effective density of the NPs is obtained for the stable NP dispersions using the volumetric centrifugation method, while cellular dosimetry calculations are done using available cellular computational modeling, mirroring approaches used for hydrophilic NPs. The robustness of the proposed dispersion approach is showcased using a highly hydrophobic NP model (black carbon NPs) and two culture media, RPMI medium and SABM, that are widely used in cellular studies. The proposed approach for the dispersion of hydrophobic NPs results in stable dispersions in both culture media used here. The NP effective density of 1.03–1.07 g/cm3 measured here for black carbon NPs is close to the culture media density, resulting in slow deposition on the cells over time. So, the present methodology for dispersion and dosimetry of hydrophobic NPs is essential for the design of dose–response studies and overcoming the challenges imposed by slow particle deposition.
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Xu, Jinglu, Jihu Wang, Shaoguo Wen, Shengnan Ding, Jia Song, Sihong Jiang, and Haopeng Wang. "Preparation and Dispersion Performance of Hydrophobic Fumed Silica Aqueous Dispersion." Polymers 15, no. 17 (August 22, 2023): 3502. http://dx.doi.org/10.3390/polym15173502.
Full textAbstract:
Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. A series of experiments were conducted on the HFS-dispersing technology in this study. The size and structure of HFS primary particles were observed via transmission electron microscopy (TEM). The measurement results of the TEM were D50 = 13.6 nm and D90 = 19.7 nm, respectively. The particle size and dispersion performance of HFS were tested via dynamic light scattering (DLS). Additionally, the HFS aqueous dispersion was prepared and compounded with waterborne polyacrylic latex and polyurethane resin. The elemental distribution of the coatings was characterized using energy dispersive spectroscopy (EDS). The results show that the HFS in a non-ionic polymer dispersant had the best dispersion performance. The particle size of the HFS in the aqueous dispersion is related to the dispersion conditions. Under optimized conditions, the HFS aqueous dispersion can be prepared with a particle size of D50 = 27.2 nm. The HFS aqueous dispersion has stable storage stability. Even after storage for 47 d, the particle size still did not change significantly.