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Статті в журналах з теми "Solutions solides – Stabilité – Solubilité":
1
El Ouenzerfi, R., C. Goutaudier, M. T. Cohen-Adad, G. Panczer, M. T. Ayedi, and N. K. Ariguib. "Solubilité de l'uranium dans les solutions solides d'apatite phospho-silicatée." Journal de Physique IV (Proceedings) 113 (January 2004): 111–14. http://dx.doi.org/10.1051/jp4:20040024.
2
Alpers, Charles N., Darell Kirk Nordstrom, and James W. Ball. "Solubility of jarosite solid solutions precipitated from acid mine waters, Iron Mountain, California, U.S.A. Solubilité des solutions solides de jarosite précipitées à partir des eaux minières acides, Iron Mountain, Californie, U. S. A." Sciences Géologiques. Bulletin 42, no. 4 (1989): 281–98. http://dx.doi.org/10.3406/sgeol.1989.1829.
3
Tanaka, Ryoma, Yusuke Hattori, Yukun Horie, Hitoshi Kamada, Takuya Nagato, and Makoto Otsuka. "Characterization of Amorphous Solid Dispersion of Pharmaceutical Compound with pH-Dependent Solubility Prepared by Continuous-Spray Granulator." Pharmaceutics 11, no. 4 (April 3, 2019): 159. http://dx.doi.org/10.3390/pharmaceutics11040159.
Анотація:
A continuous-spray granulator (CTS-SGR) is a one-step granulation technology capable of using solutions or suspensions. The present research objectives were, (1) to reduce the manufacturing operations for solid dosage formulations, (2) to make amorphous solid dispersion (ASD) granules without pre-preparation of amorphous solids of active pharmaceutical ingredients (API), and (3) to characterize the obtained SGR granules by comprehensive pharmaceutical analysis. Rebamipide (RBM), a biopharmaceutical classification system class IV drug, that has low solubility or permeability in the stomach, was selected as a model compound. Five kind of granules with different concentrations of polyvinylpyrrolidone/vinyl acetate copolymer (PVP-VA) were prepared using a one-step SGR process. All of the SGR granules could be produced in amorphous or ASD form and their thermodynamic stability was very high because of high glass transition temperatures (>178 °C). They were unstable in 20 °C/75%RH; however, their stability was improved according to the proportion of polymer. The carboxy group of RBM was ionized in the granules and interactions appeared between RBM and PVP-VA, with the formation of an ASD confirmed and the solubility was enhanced compared with bulk RBM crystals. The SGR methodology has the possibility of contributing to process development in the pharmaceutical industry.
4
РЯЗАНЦЕВА, К. А., Н. Е. ШЕРСТНЕВА, Е. Ю. АГАРКОВА, and Н. А. ЖИЖИН. "INFLUENCE OF ULTRAVIOLET MODIFIED WHEY PROTEINS ON THE STABILITY OF THE STABILITY OF THE STABILIZED MILK CLOUD." Известия вузов. Пищевая технология, no. 2-3(392) (July 26, 2023): 83–92. http://dx.doi.org/10.26297/0579-3009.2023.2-3.14.
Анотація:
Ультрафиолетовое (УФ) облучение инициирует частичную полимеризацию сывороточных белков моло- ка, способствуя формированию небольших фракций растворимых белковых агрегатов. Цель исследования – оценка формирования структуры,реологических и влагоудерживающих свойств кисломолочных сгустков при сквашивании модифицированных УФ-воздействием растворовконцентратов сывороточных белков (КСБ). Растворы сывороточных белков (СБ) с концентрацией белка 3, 5 и 7% подвергали УФ-облучению в дозах 15, 30 и 45 Дж/мл (254 нм, поток излучения 7,3 Вт, зазор 400 мкм, скорость потока 6,67 мл/с). В полученных растворахоценивали растворимость белка и степень денатурации бета-лактоглобулина. Наибольшие изменения были идентифицированы в растворе СБ с наи- меньшим содержанием сухих веществ (~ 4%, м. д. белка 3%), в котором в диапазоне доз от 0 до 30 Дж/мл прослежива- лось повышение растворимости белка с (93,26 ± 1,2) до (98,48 ± 0,9)% и последующее снижение данного показателя при 45 Дж/мл до (93,7 ±1)%. В исследуемых растворах значения степени денатурации не превышали 25%, что говорит о формировании небольших фракций растворимых агрегатов. В диапазоне доз облучения от 0 до 45 Дж/мл накопле- ние свободных сульфгидрильных групп (более чем в 3 раза)и белковых карбонилов (менее чем в 2 раза) в модифици- рованных растворах СБ носило линейный характер и доказывало формированиеновых ковалентных взаимодействий между мономерами бета-лактоглобулина. При последующем сквашивании растворов СБ образование сгустка было зафиксировано в модельных системах, подвергнутых дозе облучения 30 и 45 Дж/мл. Исследуемые образцы с м. д. белка 5 и 7% демонстрировали отсутствие синерезиса, влагоудерживающую способность более 92% и высокие по- казатели вязкости. На основе полученных данных можно заключить, что технологию УФ-обработки сывороточных белков целесообразно проводить для улучшения структурно-механических характеристик кисломолочных продуктов. Ultraviolet (UV) irradiation initiates partial polymerization of whey milk proteins, contributing to the formation of small fractions of soluble protein aggregates. The purpose of the study was to assess the formation of the structure, rheological and water-retaining properties of sour-milk clots during the fermentation of solutions of whey protein concentrates (WPC) modified by UV-exposure. Whey protein solutions (SP) with aprotein concentration of 3, 5 and 7% were exposed to UV-irradiation at doses of 15, 30 and 45 J/ml (254 nm, radiation flux 7,3 W, gap 400 μm, flow rate 6,67 ml/ml). Protein solubility and the degree of beta-lactoglobulin denaturation were evaluated in the resulting solutions. The greatest changes were identified in the SB solution with the lowest content of solids (~ 4%, ppm protein 3%), in which, in the dose range from 0 to 30 J/ml, an increase in the solubility of protein c (93,26 ± 1,2) to (98,48 ± 0,9)% and a subsequent decrease in this indicator at 45 J/ml to (93,7 ± 1)%. In the studied solutions, the values of the degree of denaturation did not exceed 25%, which indicates the formation of small fractions of soluble aggregates. In the range of irradiation doses from 0 to 45 J/ml, the accumulation of free sulfhydryl groups (more than 3 times) and protein carbonyls (less than 2 times) in modified SB solutions was linear and proved the formation of new covalent interactions between beta-lactoglobulinmonomers. During the subsequent fermentation of SB solutions, the formation of a clot was recorded in model systems subjected to an irradiation dose of 30 and 45 J/mL. The studied samples with ppm protein 5 and 7% showed no syneresis, water-holding capacity of more than 92% and high viscosity. Based on the data obtained, it can be concluded that it is advisable to carry out the technology of UV-treatment of whey proteins to improve the structural and mechanical characteristics of fermented milk products.
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Sathisaran, Indumathi, and Sameer Dalvi. "Engineering Cocrystals of Poorly Water-Soluble Drugs to Enhance Dissolution in Aqueous Medium." Pharmaceutics 10, no. 3 (July 31, 2018): 108. http://dx.doi.org/10.3390/pharmaceutics10030108.
Анотація:
Biopharmaceutics Classification System (BCS) Class II and IV drugs suffer from poor aqueous solubility and hence low bioavailability. Most of these drugs are hydrophobic and cannot be developed into a pharmaceutical formulation due to their poor aqueous solubility. One of the ways to enhance the aqueous solubility of poorlywater-soluble drugs is to use the principles of crystal engineering to formulate cocrystals of these molecules with water-soluble molecules (which are generally called coformers). Many researchers have shown that the cocrystals significantly enhance the aqueous solubility of poorly water-soluble drugs. In this review, we present a consolidated account of reports available in the literature related to the cocrystallization of poorly water-soluble drugs. The current practice to formulate new drug cocrystals with enhanced solubility involves a lot of empiricism. Therefore, in this work, attempts have been made to understand a general framework involved in successful (and unsuccessful) cocrystallization events which can yield different solid forms such as cocrystals, cocrystal polymorphs, cocrystal hydrates/solvates, salts, coamorphous solids, eutectics and solid solutions. The rationale behind screening suitable coformers for cocrystallization has been explained based on the rules of five i.e., hydrogen bonding, halogen bonding (and in general non-covalent bonding), length of carbon chain, molecular recognition points and coformer aqueous solubility. Different techniques to screen coformers for effective cocrystallization and methods to synthesize cocrystals have been discussed. Recent advances in technologies for continuous and solvent-free production of cocrystals have also been discussed. Furthermore, mechanisms involved in solubilization of these solid forms and the parameters influencing dissolution and stability of specific solid forms have been discussed. Overall, this review provides a consolidated account of the rationale for design of cocrystals, past efforts, recent developments and future perspectives for cocrystallization research which will be extremely useful for researchers working in pharmaceutical formulation development.
6
Zhang, Xuehong, Yinian Zhu, Honghu Zeng, Dunqiu Wang, Jie Liu, Huili Liu, Meifang Qian, and Liwei Xu. "Dissolution and solubility of the arsenate - phosphate hydroxylapatite solid solution [Ca5(PxAs1 - xO4)3(OH)] at 25°C." Environmental Chemistry 8, no. 2 (2011): 133. http://dx.doi.org/10.1071/en10102.
Анотація:
Environmental contextApatites form a large family of minerals and compounds that can incorporate a variety of ions, including arsenate that can substitute for phosphate. Apatites may therefore control the concentration of arsenic in some aqueous environments. This manuscript describes the synthesis and characterisation of the arsenate–phosphate hydroxylapatite solid solution and the solid solution–aqueous solution interaction. Abstract Nine different members of the arsenate–phosphate hydroxylapatite solid solution [Ca5(PxAs1–xO4)3(OH)] were prepared and characterised by various techniques, and then dissolution of the synthetic solids was studied at 25°C and pH 2 in a series of batch experiments. The concentrations of aqueous arsenate species increased rapidly at the beginning of the dissolution and reached a steady-state after 480 h. The concentrations of aqueous phosphate species increased very fast initially and reached a peak value within the first hour of dissolution and then declined slowly with time and remained constant after 240–360 h. The solubility of the Ca5(PxAs1–xO4)3(OH) solid solution increased and its stability decreased with an increase in the mole fraction of Ca5(AsO4)3(OH). The dissolution followed or slightly overshot the Lippmann solutus curve, then approached the solutus curve. The Ca5(AsO4)3(OH)-poor solid solution was in equilibrium with the arsenate-rich aqueous solution.
7
Mesmer, R. E., and C. F. Baes. "Review of Hydrolysis Behavior of Ions in Aqueous Solutions." MRS Proceedings 180 (1990). http://dx.doi.org/10.1557/proc-180-85.
Анотація:
ABSTRACTThe word “hydrolysis,” literally “water splitting,” refers here to those reactions of metallic ions with water that liberate protons and produce hydroxy or oxy complexes in solution and precipitate hydroxide or oxide solids. Over the wide range of pH available in water, the strong tendency of hydroxide to bond to and bridge among cations leads to a multitude of species for many of the metals. Properties of the metal ion such as “hardness” and, especially, charge and size, determine the strength of these interactions and the species formed by each. Over 200 mononuclear species have been identified that predominate in dilute solutions across the pH scale. It is the stability of these species that largely determines the pH dependence of the solubility of the oxide or hydroxide solid formed. Both the tendency of the variety of polynuclear species (those containing more than one metal ion) to form and the solubility of the hydrolytic solid correlate with the stability of the first mononuclear species. Other correlations allow one to predict the enthalpy and entropy of a variety of hydrolysis reactions, and therefore the dependence of the stability of hydrolysis products on temperature.
8
Torrero, M. E., I. Casas, M. Aguilar, J. De Pablo, J. Gimenez, and J. Bruno. "The Solubility of Unirradiated UO2 In Both Perchlorate And Chloride Test Solutions. Influence of the Ionic Medium." MRS Proceedings 212 (1990). http://dx.doi.org/10.1557/proc-212-229.
Анотація:
ABSTRACTThe solubility of a crystalline unirradiated UO2 (s) has been studied under reducing conditions at 25°C in three different ionic media: 0.008 mol dm–3 NaCIO4, 1 and 5 mol dm-3 NaCl+. The species responsible for the solubility in perchlorate medium are U(OH)3 and U(OH)4, with the stability constants log β13 = -0.4(±0.2) and log β14 = -5.7(±0.1), respectively. The solubility in both1! and 5 M chloride media is explained at pH values higher than 6 by the species U(OH)4 with log β14 = -5.5(±0.2) while at lower pH values an abnormal behaviour is observed, with higher uranium concentrations in solution and a proton independent solubility for pH values lower than 4. The XPS observations of the reacted solids do not show the presence of solid surface phases other than uranium dioxide, with an upper oxidation state of UO2.1.
9
YOUAN, Bi-Botti Celestin. "Systèmes nanoparticulaires : Applications phytopharmaceutiques et cosmétiques." Journal Africain de Technologie Pharmaceutique et Biopharmacie (JATPB) 2, no. 3 (December 20, 2023). http://dx.doi.org/10.57220/jatpb.v2i3.116.
Анотація:
Cette présentation se focalise sur les principes de synthèse des vecteurs nanoparticulaires suivie de leur application en pharmacie et en cosmétologie. La nanotechnologie est une technologie multidisciplinaire pour la manipulation des objets (atomes et molécules) de taille inférieure à 100 nanomètres. Les nanoparticules peuvent être synthétisées par la méthode de top down (du haut en bas) dessous) et bottom up (du bas en haut). Dans cette présentation nous nous intéresserons aux méthodes de bottom up utilisant soit des polymères préformés ou formés in situ pendant la synthèse. Les méthodes de synthèse sont l’émulsification/évaporation de solvant, l’émulsification/déplacement de solvant, la polymérisation interfaciale, l’utilisation de polymères naturels, des fluides supercritiques et la production en milieu non aqueux (e.g. PRINT).
Ces techniques permettent d’obtenir diverses classes de nanoparticules organiques (exemple des liposomes) ou inorganiques (exemple des particules d’argent ou d’or). La nanotechnologie améliore les propriétés physicochimiques (stabilité, solubilité et dissolution), biopharmaceutiques (pharmacocinétiques/libération contrôlée), thérapeutiques et toxicologiques des principes actifs utilises. L’application de la nanotechnologie en pharmacie a déjà abouti depuis 1995 a l’enregistrement de plus de 70 nouveaux produits approuvés par la US FDA (Food and Drug Administration) dont la plupart sont utilisés dans le traitement amélioré du cancer et des maladies infectieuses. En phytomedicine, la nanotechnologie améliore non seulement la production agricole/vétérinaire et la synthèse verte sans solvants organiques nocifs, mais elle permet aussi de concrétiser le concept émergent d’économie circulaire (par exemple l’utilisation des écorces de noix de coco pour faire du charbon actif de grande utilité en pharmacie, la purification de l’eau et des minéraux précieux). Ces méthodes aident aussi à
optimiser l’incorporation des huiles essentielles (naturellement hydrophobes) dans les milieux aqueux dans toute formulation galénique ou cosmétique.
L'application de la nanotechnologie en cosmétique est aussi en demande croissante et utilise notamment les nanoémulsions pour une meilleure pénétration transcutanée et les lipides solides pour leurs effets occlusifs.
En conclusion, la nanotechnologie offre d’énormes potentiels pour l’émergence de la pharmacie industrielle en Afrique si les grands challenges ou défis des étapes clés du procédé de l’industrialisation (R&D, formulation, production, contrôle de qualité, emballage, régulation) peuvent être maitrisés
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Tripathi, Devika, Manjunatha Prabhu B.H, Jagannath Sahoo, and Jyoti Kumari. "Navigating the Solution to Drug Formulation Problems at Research and Development Stages by Amorphous Solid Dispersion Technology." Recent Advances in Drug Delivery and Formulation 17 (December 7, 2023). http://dx.doi.org/10.2174/0126673878271641231201065151.
Анотація:
Abstract: Amorphous Solid Dispersions (ASDs) have indeed revolutionized the pharmaceutical industry, particularly in drug solubility enhancement. The amorphous state of a drug, which is a highenergy metastable state, can lead to an increase in the apparent solubility of the drug. This is due to the absence of a long-range molecular order, which results in higher molecular mobility and free volume, and consequently, higher solubility. The success of ASD preparation depends on the selection of appropriate excipients, particularly polymers that play a crucial role in drug solubility and physical stability. However, ASDs face challenges due to their thermodynamic instability or tendency to recrystallize. Measuring the crystallinity of the active pharmaceutical ingredient (API) and drug solubility is a complex process that requires a thorough understanding of drug-polymer miscibility and molecular interactions. Therefore, it is important to monitor drug solids closely during preparation, storage, and application. Techniques such as solid-state nuclear magnetic resonance (ssNMR), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and dielectric spectroscopy have been successful in understanding the mechanism of drug crystallization. In addition, the continuous downstream processing of drug-loaded ASDs has introduced new automated methods for consistent ASD production. Advanced techniques such as hot melt extrusion, KinetiSol, electro spraying, and electrospinning have gained popularity. This review provides a comprehensive overview of Amorphous Solid Dispersions (ASDs) for oral drug delivery. It highlights the critical challenges faced during formulation, the impact of manufacturing variables, theoretical aspects of drug-polymer interaction, and factors related to drug-polymer miscibility. ASDs have been recognized as a promising strategy to improve the oral bioavailability of poorly water-soluble drugs. However, the successful development of an ASD-based drug product is not straightforward due to the complexity of the ASD systems. The formulation and process parameters can significantly influence the performance of the final product. Understanding the interactions between the drug and polymer in ASDs is crucial for predicting their stability and performance.
Дисертації з теми "Solutions solides – Stabilité – Solubilité":
1
Samsoen, Simon. "Synthèses et caractérisations physiques de matrices polymères pour la formulation de dispersions solides amorphes curcumine/polyvinylpyrrolidone." Electronic Thesis or Diss., Université de Lille (2022-....), 2024. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2024/2024ULILR001.pdf.
Анотація:
L'objectif de ce travail de thèse est d'améliorer la connaissance fondamentale des mécanismes intervenant dans la formation de dispersions solides amorphes (DSA) d'un principe actif pharmaceutique au sein d'un excipient polymère, en particulier l'impact de l'architecture macromoléculaire des polymères sur la stabilité physique des DSA.Des polymères de poly(N-vinylpyrrolidone) (PVP) de faible dispersité, de masses molaires et fonctionnalités d'extrémités de chaînes différentes sont d'abord synthétisés de façon contrôlée par RAFT/MADIX (Reversible Addition-Fragmentation chain Transfer/ Macromolecular design by Interchange of Xanthates). Ils sont ensuite utilisés pour la formulation, par co-broyage et évaporation de solvant, de mélanges à base de curcumine (CUR). La caractérisation physico-chimique avancée du PVP, de la CUR et des DSA obtenues nous permet d'établir le diagramme de phases (courbe de solubilité) et d'états (évolution de la température de transition vitreuse (Tg)) CUR/PVP. Ce diagramme permet, d'une part, de mieux comprendre les conditions de stabilité des DSA CUR/PVP et l'impact de la masse molaire ou de la fonctionnalité des extrémités de chaînes du PVP. D'autre part, la comparaison avec des DSA formulées avec du PVP commercial de forte dispersité nous permet d'établir le rôle particulier de la dispersité sur la Tg du PVP et celle des DSA CUR/PVP. En effet, dans le cas de DSA formulées avec du PVP de forte dispersité, les résultats montrent une diminution de Tg pour des taux élevés de PVP qui dévoile une compétition entre le développement d'interactions attractives entre CUR et PVP et un effet plastifiant engendré par la grande distribution des masses molaires du PVP. Enfin, ce travail révèle que l'utilisation de PVP synthétisés de façon contrôlée permet d'obtenir des DSA stables sur un domaine de températures et de concentrations en curcumine plus étendu que pour des DSA formulées avec un PVP industriel de forte dispersitéThis thesis aims at improving our fundamental knowledge on the mechanisms involved in the formation of amorphous solid dispersions (ASD) of a drug within a polymer excipient, in particular the impact of the macromolecular architecture on the physical stability of ASD.Poly(N-vinylpyrrolidone) (PVP) polymers with low dispersity and different molar masses and chain-end functionalities are first synthesised in a controlled manner by RAFT/MADIX (Reversible Addition-Fragmentation chain Transfer/ Macromolecular design by Interchange of Xanthates). They are then used to formulate, by co-milling and solvent evaporation processes, mixtures with curcumin (CUR). The advanced physico-chemical characterisation of PVP, CUR and the obtained ASD enables us to establish the CUR/PVP phase (solubility limit) and state (glass transition temperature (Tg) evolution) diagrams. On the one hand, this diagram allows us to better understand the stability conditions of CUR/PVP ASD and the impact of the PVP molar mass and chain-end functionality. On the other hand, comparison with ASD formulated with high dispersity commercial PVP allows us to highlight the specific role of the dispersity on the Tg of PVP and of CUR/PVP ASD. Indeed, for ASD formulated with high dispersity PVP, results show the decrease of Tg at high PVP contents, which unveils a competition between the development of attractive interactions between CUR and PVP and a plasticising effect induced by the broad distribution of PVP molar masses. Finally, this work reveals that the use of PVP synthesised in a controlled manner allows to obtain stable ASD over a broader range of temperatures and CUR concentrations than for ASD formulated with industrially available PVP of high dispersity
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Costin, Dan Tiberiu. "Solutions solides d'uranothorites : De la préparation à la dissolution." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0026/document.
Анотація:
La coffinite, USiO4, constitue l'une des phases pouvant être formées lors de l'altération d'un combustible usagé en conditions réductrices, après la dégradation des barrières de confinement. Une étude visant à déterminer les données thermodynamiques associées à la coffinite via une approche reposant sur la préparation de solutions solides d'uranothorites (Th1-xUxSiO4) a ainsi été développée au cours de ce travail. Dans un premier temps, la préparation des échantillons d'uranothorite a été entreprise avec succès en conditions hydrothermales. L'obtention systématique d'échantillons polyphasés pour x > 0,2 a toutefois permis de souligner les difficultés d'ordre cinétique liées à la synthèse en phase pure d'échantillons enrichis en uranium, dont le pôle pur constitué par la coffinite. La caractérisation des différents échantillons a néanmoins permis de confirmer la formation d'une solution solide idéale sur l'ensemble du domaine de composition et a conduit à la constitution d'une base de données spectroscopiques concernant ces systèmes chimiques. Par la suite, la purification des échantillons d'uranothorite a été entreprise par le biais de différents protocoles expérimentaux, basés sur des méthodes physiques (dispersion-centrifugation) ou chimique (dissolution préférentielle des phases secondaires). Cette dernière a ainsi montré l'élimination complète des impuretés (oxyde mixte Th1-yUyO2, et silice amorphe) à l'issue de cycles de lavage en milieu acide puis basique. Enfin, des expériences de dissolution ont été réalisées sur une série d'uranothorites (0 ≤ xexp. ≤ 0,5) et ont permis de déterminer l'influence de la composition, du pH et de la température sur la vitesse de dissolution normalisée des échantillons. Par ailleurs, les données thermodynamiques associées, telles que l'énergie d'activation, indiquent que la réaction de dissolution semble contrôlée par des phénomènes de surface. Après atteinte de l'équilibre, les constantes de solubilité analogues des uranothorites ont également été déterminées, permettant ainsi d'atteindre par extrapolation les données relatives à la coffinite et de conclure quant à l'inversion de la réaction de coffinitisation en fonction de la températureUSiO4 coffinite appears as one of the potential phases formed in the back-end of the alteration of spent fuel, in reducing storage conditions. A study aiming to assess the thermodynamic data associated with coffinite through an approach based on the preparation of Th1-xUxSiO4 uranothorite solid solutions was then developed during this work. First, the preparation of uranothorite samples was successfully undertaken in hydrothermal conditions. However, the polyphased samples systematically formed for x > 0,2 underlined the kinetic hindering linked with the preparation of uranium-enriched samples, including coffinite end-member. Nevertheless, the characterization of the various samples led to confirm the formation of an ideal solid solution and allowed the constitution of a spectroscopic database. The purification of the samples was then performed by the means of different protocoles based on physical (dispersion-centrifugation) or chemical (selective dissolution of secondary phases) methods. This latter led to a complete of the impurities (Th1-yUyO2 mixed oxide and amorphous silica) through successive washing steps in acid then basic media. Finally, dissolution experiments were undertaken on uranothorite samples (0 ≤ xexp. ≤ 0,5) and allowed pointing out the influence of composition, pH and temperature on the normalized dissolution rate of the compounds. Also, the associated thermodynamic data, such as activation energy, indicate that the reaction is controlled by surface reactions. Once the equilibrium is reached, the analogous solubility constants were determined for each composition studied, then allowing the extrapolation to coffinite value. It was then finally possible to conclude on the inversion of coffinitisation reaction with temperature
3
Dubois, Rémy. "Investigation numérique de la stabilité et de la solubilité des solides pharmaceutiques amorphes visant à améliorer la biodisponibilité des médicaments." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10062/document.
Анотація:
La grande majorité des médicaments (principes actifs et excipients) sont généralement préparés à l'état solide (poudre, comprimés, gélules) qui peut exister sous différentes formes : polymorphes cristallins ou amorphes. Ces formes se comportent différemment dans le corps humain et ont un impact considérable sur l'efficacité thérapeutique et la stabilité du médicament. Contrôler et prédire les propriétés de l'état solide durant la fabrication et le stockage sont donc les principaux problèmes dans le développement de nouveaux produits pharmaceutiques. La principale motivation de ce travail de thèse est qu'il demeure de nombreux problèmes fondamentaux et pratiques que l'état de l’art actuel en pharmacie ne peut pas traiter efficacement. Une approche plus fondamentale est donc nécessaire et ont motivé le choix de cette étude. Un programme de recherche portant sur l’état physique des composés de base des médicaments- des petites molécules organiques – a été mené. Cette problématique de recherche fondamentale avec une finalité appliquée a impliqué des investigations sur:La prédiction de la stabilité des polymorphes cristallins de composés pharmaceutiques.Les propriétés physiques de l’eau à l’interface de matériaux cristallins et amorphes.La cinétique d'agrégation d'un composé modèle de la pharmacieMost of the active pharmaceutical ingredients and excipients are generally formulated in solid state which may exist under several different forms including crystalline polymorphs and amorphous forms. Such forms can exhibit different behaviors and have significant impact on the therapeutical efficiency and the stability of the drug product. This thesis was mainly motivated by the fundamental and practical difficulties that remained unsolved by the actual state of the art in pharmaceutical science. A fundamental approach has thus been necessary and a research program on solid state physics of basic pharmaceutical compounds (small organic molecules) has been conducted on: - Prediction of stability of crystalline polymorphs of pharmaceutical compounds;- Physical properties of interfacial water in contact with crystalline and amorphous materials;- Aggregation kinetic of a model pharmacutical compound
4
Janvier, Catherine. "Solutions solides de zirconium dans la cérine : modèle thermodynamique et stabilité thermique a haute température." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1998. http://tel.archives-ouvertes.fr/tel-00841807.
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Janvier, Catherine. "Solutions solides de zirconium dans la cérine : modèle thermodynamique et stabilité thermique à haute température." Grenoble INPG, 1998. http://tel.archives-ouvertes.fr/tel-00841807.
Анотація:
Les équilibres oxydes-dioxygène gazeux ainsi que la stabilité thermique texturale de six solutions solides de zirconium dans la cérine, Ce#1-x Zr#x O#2 (O < x ≤0,36) ont été étudiés. L'étude des équilibres entre les solutions solides et le dioxygène gazeux par thermogravimetrie à 600°C à montré que celles-ci n'ont pas un comportement ideal. Un modèle thermodynamique simple de solution strictement régulière pseudo-ternaire faisant intervenir les défauts ponctuels des solutions permet de les décrire au mieux. Il devient alors possible de connaître les variations des concentrations en défauts ponctuels des solutions en fonction de la température, de la pression en oxygène et de la concentration en zirconium. L'étude cinétique, par calcination à 950°C des solutions solides, de la chute de surface spécifique, à révélé sur la courbe de vitesse de chute de surface des solutions en fonction de la concentration en zirconium, un minimum (0 < x < 0,09) puis un maximum (0,14 < x < 0,19) de vitesse. L'oxygène n'a pas d'influence visible sur cette vitesse. Un mécanisme de grossissement de grains, analogue à celui de la cérine, à été proposé pour interpréter les variations de la vitesse de chute de surface spécifique en fonction de la concentration en zirconium, les solutions solides étant décrites par le modèle thermodynamique pseudo-ternaire et la vitesse du processus étant determinée par un régime mixte de diffusion des lacunes de cérium et d'oxygène.
6
Fikar, Ondřej. "Ab initio výpočty křivek rozpustnosti tuhých roztoků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400461.
Анотація:
This diploma thesis is focused on a theoretical study of the phase stability of solid solutions in selected aluminium and silver alloys. The ab initio calculations were performed using projected augmented waves method and the thermal dependencies of thermodynamic quantities were acquired using phonon calculations. The main focus of this work is the of aluminium-germanium alloy, while the other examined alloys (Al-Pb, Ag-Ge and Ag-Pb) serve the purpose of comparison of the solid solubility prediction and its reliability in systems with different composition. The temperatures, at which the solid solutions become stable, were evaluated using the energy difference between possible states and this evaluation was carried out for different contributions to the total energy. Also the electronic and phonon densities of states were calculated for all pure elements and solid solutions. The temperatures of solubility were compared to the experimental ones provided by the CALPHAD method and the individual contributions to the total energy were determined and depicted. The results obtained in this work tend to underestimate temperatures of solubility of individual solid solutions by hundreds of Kelvin.
7
Costenoble, Sylvain. "Modélisation de la coprécipitation d'oxalates mixtes d'uranium et de plutonium dans le cadre du recyclage du combustible nucléaire : solubilité des solutions solides oxalate." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10179/document.
Анотація:
Les nouveaux procédés à l’étude pour les nouvelles générations d’usine de traitement/recyclage du combustible nucléaire privilégient un mode de cogestion de l’uranium et du plutonium. Dans le procédé COEX TM, une des opération-clés correspond à la coconversion de l’uranium(IV) et du plutonium(III) par coprécipitation oxalique. Elle conduit à un oxyde mixte destiné à la fabrication de combustible via la synthèse puis la calcination d’un précurseur de type solution solide oxalate. La modélisation de l’étape de coprécipitation oxalique, support d’une meilleure compréhension du procédé, s’appuie sur le calcul de la sursaturation dont l’expression est fonction de données thermodynamiques relatives à la formation de la solution solide oxalate. Ces données thermodynamiques ont été acquises au moyen de mesures de solubilité effectuées sur des solutions solides oxalate du type uranium(IV)-néodyme(III), le néodyme(III) simulant le comportement du plutonium(III). A partir du développement d’une méthode analytique de spéciation des actinides en solution, un caractère non congruent de l’interaction entre la solution solide et la phase aqueuse est mis en évidence. Sur la base des constantes de réaction des équilibres mis en jeu, un modèle tiré de la théorie de LIPPMANN permet de prédire l’état du système solution solide-phase aqueuse à l’équilibre thermodynamique. La méthodologie a été étendue aux oxalates mixtes analogues de type U(IV)-Pu(III) et U(IV)-Am(III) démontrant la validité du modèle pour ces systèmesChemical processes for future spent fuel treatment and recycling for new generation facilities are oriented on uranium and plutonium co-management. In the COEX TM process, one of the key operation consists of uranium(IV)-plutonium(III) co-conversion by oxalic co-precipitation. This leads to a mixed oxide for fuel production via the synthesis and the calcination of an oxalate solid solution precursor. Oxalic coprecipitation modeling, support of a better understanding of the process, is based on the supersaturation calculation whose expression is a function of thermodynamic data related to the oxalate solid solution formation.These thermodynamic data are acquired thanks to solubility measurements realised on uranium(IV)-neodymium(III) oxalate solid solutions, where neodymium(III) simulates the plutonium(III) behaviour. From the development of an actinide speciation analytical method, the non congruent interaction between the solid solution phase and the aqueous phase is observed. On the basis of the reaction constants of the occurring equilibria, a model, extracted from the LIPPMANN’s theory, allows to predict the state of the solid solution-aqueous solution system at thermodynamic equilibria. This methodology was extended to mixed oxalates U(IV)-Pu(III) and U(IV)-Am(III) demonstrating the model validity for these systems
8
Nadaud, Camille. "Amélioration de la solubilité de principes actifs BCS classe 2 par obtention de dispersions solides." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2016. http://www.theses.fr/2016EMAC0001.
Анотація:
En raison de leur complexité croissante, la solubilité des nouvelles entités chimiques en milieu aqueux est de plus en plus faible. Ainsi, le développement de beaucoup de principes actifs échoue à cause d’une hydrosolubilité insuffisante. De nombreuses technologies existent pour améliorer la solubilité et/ou solubilisation de tels composés. Cette thèse est ciblée sur la formulation de dispersions solides amorphes par extrusion à chaud. En particulier, un principe actif d’intérêt industriel sera formulé en utilisant une extrudeuse bi-vis disponible sur la plateforme Gala®. Cette technologie autorise l’utilisation d’un grand nombre de matrices, ce qui peut nécessiter un grand nombre d’essais expérimentaux. Une attention particulière est donc portée à l’utilisation de méthodes prédictives de la miscibilité entre les composants qui peuvent ainsi permettre une première sélection des matrices. Sur la base de ces résultats, une étude sur le procédé de hot melt extrusion a ensuite été réaliséeThe aqueous solubility of new chemical entities is increasingly weak, due to their complex structure, and many API fail in development due to insufficient solubility. Many technologies exist to enhance the solubility and / or dissolution of such compounds in aqueous media. Among all of these methods, this thesis is focused on the formulation of amorphous solid dispersions by hot melt extrusion. A lot of matrix can be used to formulate with this technology, so few methods to estimate miscibility between API and matrices will also be presented in this thesis. Finally, a study about the hot melt extrusion process will also be presented
9
Thakare, Kalpana. "THE EVALUATION OF LARCH ARABINOGALACTAN AS A NEW CARRIER IN THE FORMULATION OF SOLID DISPERSIONS OF POORLY WATER- SOLUBLE DRUGS." Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/232942.
Анотація:
Pharmaceutical SciencesPh.D.
Advanced drug discovery techniques have produced more lipophilic compounds. Formation of an amorphous solid dispersion of such poorly water-soluble drugs improves their solubility and dissolution. This results in greater in vivo bioavailability. Thus, it is one of the recent trends in the development of oral dosage forms. In solid dispersions, the carrier is crucial for ensuring the functionality and stability of these systems. Larch arabinogalactan FiberAid grade (AGF) is generally recognized as safe (GRAS) designated, amorphous polymer. The objective of this dissertation project was to perform a comprehensive evaluation of AGF as a carrier for amorphous solid dispersions. First, a detailed characterization of the AGF polymer was performed. A special focus on its use as a solid dispersion carrier was emphasized. The glass transition temperature and the degradation temperature of the AGF polymer were ~82 oC and ~185 oC, respectively. The AGF polymer had good hygroscopicity. Ibuprofen-AGF solid dispersions were evaluated for dissolution enhancement. Ibuprofen-Hydroxypropyl methylcellulose grade K3 (HPMCK3) solid dispersions were investigated simultaneously as a control polymer dispersion. The ibuprofen-AGF solid dispersions were amorphous at nearly 20% ibuprofen load. The dissolution of the ibuprofen from AGF solid dispersions was significantly greater than that of the neat ibuprofen. The formation of the amorphous state of ibuprofen and solution-state ibuprofen-AGF interactions were the mechanisms of the ibuprofen dissolution enhancement. At a 10% ibuprofen load, the dissolution of the AGF solid dispersion was found greater than that of the dissolution of the HPMCK3 solid dispersion. Secondly, the itraconazole-AGF solid dispersions and the ketoprofen-AGF solid dispersions were characterized and compared them with the ibuprofen-AGF solid dispersions. The comparisons were established for the miscibility and dissolution enhancement. The order of increase in dissolution was ketoprofen-AGF solid dispersions > itraconazole-AGF solid dispersions> ibuprofen-AGF solid dispersions. The same order was observed for the solid-state miscibility of these drug-AGF solid dispersions. Additionally, the solid dispersions of 9 drugs with the AGF polymer were investigated to elucidate the detailed mechanism of drug crystallization inhibition by the AGF polymer. The inherent tendency of the AGF polymer to inhibit the drug crystallization, drug-AGF solid-state hydrogen bonding and the anti-plasticizing effect of AGF were the mechanisms underlying the crystallization inhibition by the AGF polymer. Last, a storage stability of ibuprofen-AGF amorphous solid dispersions after storage under accelerated conditions (for 3 months) and ambient conditions (for 6 months) was investigated. The amorphous ibuprofen from AGF solid dispersions was physically and chemically stable under stability conditions. In summary, the AGF polymer was evaluated as a novel carrier for formation of an amorphous solid dispersions. The studies established that the AGF polymer was comparable to HPMCK3 polymer. The AGF polymer could be more advantageous than the HPMC polymer for the preparation of solid dispersion when faster dissolution is desired at lower drug load.
Temple University--Theses
10
Aumelas, Angeline. "Broyage de composés pharmaceutiques : changements d'états physiques et manipulation de la stabilité." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10160/document.
Анотація:
Ce mémoire présente l'étude d'un principe actif pharmaceutique (PA) peu soluble dans l'eau. Sa formulation à l'état amorphe serait un moyen d'augmenter sa solubilité. Tout d'abord, nous avons montré que le polymorphisme du PA est plus complexe que les deux formes polymorphiques 1 (stable) et II (méta stable) jusqu'à présent connues et liées par une relation de monotropie. Deux nouvelles formes polymorphiques métastables ont été révélées par calorimétrie et diffraction des rayons X. Nous avons ensuite montré que le broyage de la forme 1 du PA conduit à son amorphisation. Le verre obtenu présente les mêmes caractéristiques structurales que le liquide trempé. Cependant, il n'est pas stable et cristallise, au réchauffage, peu après la transition vitreuse et en quelques jours lorsqu'il est stocké à température et humidité ambiantes. Nous avons cherché à stabiliser le PA amorphe par co-amorphisation avec un excipient polymérique amorphe (HPMC) et un excipient moléculaire cristallin (tréhalose anhydre). Des solutions solides et des alliages moléculaires amorphes homogènes, qui ne peuvent pas être formés par le procédé de fusion/trempe, ont été obtenus pour toute composition par co-broyage des mélanges excipient/PA(forme 1). La stabilité au réchauffage de ces solutions solides a été nettement améliorée. Au stockage, les solutions solides HPMC/PA présentent une meilleure stabilité que les alliages vitreux tréhalose/PA (stabilité de 2 ans à température et humidité ambiantes). Cette étude montre que la valeur de la température de transition vitreuse n'est pas un paramètre suffisant pour prédire la stabilité de composés amorphes. Un mécanisme d'amorphisation par broyage est proposéLn this thesis, a study of an active pharmaceutical ingredient (APl), weakly soluble in water, is reported. Its formulation in the amorphous state would be a means to increase its solubility. First, we showed that the polymorphism of this compound is more complex than the two forms, 1 (stable) and II (metastable), till now known and linked together by a monotropic relation. Two new metastable polymorphic forms were revealed by calorimetry and X-ray diffraction. Then, we showed that the milling of the APl stable form 1 induces its amorphization. The obtained glass has the same structural characteristics than the quenched liquid. However, it is not stable and crystallizes, on heating, just after the glass transition and in a few days when stored under ambient temperature and humidity. We tried to stabilize the amorphous APl by co-amorphization with an amorphous polymeric excipient (HPMC) and with a crystalline molecular excipient (anhydrous trehalose). Homogeneous amorphous solid solutions and molecular alloys, unreachable by the meltinglquenching process, were obtained by co-milling for any composition of the mixtures excipient/API(form 1). The stability on heating of these glass solutions was really enhanced. During storages, the HPMCIAPI glass solutions present a better stability than the trehalose/API vitreous alloys (stability of 2 years under ambient temperature and humidity). This investigation shows that the glass transition temperature value is not a sufficient parameter to predict the stability of amorphous compounds. A mechanism for the amorphization by milling is proposed
Частини книг з теми "Solutions solides – Stabilité – Solubilité":
1
Dewangan, Smriti, Moonmun Dhara, and Varsha Rawat. "NANOTECHNOLOGY BASED APPROACHES FOR ENHANCING BIOAVAILABILITY OF POORLY SOLUBLE DRUGS." In Futuristic Trends in Pharmacy & Nursing Volume 3 Book 3, 245–77. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bapn3ch14.
Анотація:
Nanotechnology has emerged as a transformative field in pharmaceutical research, offering innovative solutions to tackle the long-standing challenge of poor solubility of various drugs. In this chapter, we explore the latest advancements and applications of nanotechnology-based solubility enhancement techniques. The poor aqueous solubility of drugs often leads to compromised bioavailability and therapeutic efficacy, limiting their clinical success. Nanotechnology-based approaches, such as nanosuspensions, solid lipid nanoparticles, nanoemulsions, and cyclodextrin complexes, have shown great promise in enhancing drug solubility and dissolution rates. By manipulating materials at the nanoscale, these techniques provide unique opportunities to encapsulate drug compounds, enhancing their stability and facilitating targeted delivery to specific biological sites. Moreover, the use of nanoscale carriers enables controlled and sustained drug release, leading to improved therapeutic outcomes and reduced side effects. This review highlights the versatility of nanotechnology in enhancing the solubility of hydrophobic and hydrophilic drugs alike, broadening its potential application across a wide range of pharmaceutical compounds. Additionally, the biocompatibility and biodegradability of nanomaterials play a pivotal role in ensuring their safety and clinical relevance. Despite these promising advancements, certain challenges remain, including the need for comprehensive toxicity assessments, scalability of manufacturing processes, and regulatory considerations. Nonetheless, nanotechnology-based solubility enhancement techniques hold significant promise for revolutionizing drug development and personalized medicine. In conclusion, this review underscores the transformative potential of nanotechnology-based solubility enhancement techniques in overcoming drug solubility challenges. As the field continues to evolve, further research and collaboration among academia, industry, and regulatory bodies will be essential to unlock the full therapeutic potential of nanotechnology in pharmaceutical applications.
2
Kasturi, Madhavi. "Development of Liquisolid Compacts: An Approach for Dissolution Enhancement of Poorly Aqueous Soluble Drugs." In Drug Formulation Design [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.108706.
Анотація:
Solubility plays a key role to achieve desired concentration of drug in systemic circulation and show its pharmacological action. An approach of liquisolid technique, developed by Spireas, was employed for the dissolution enhancement of poorly aqueous soluble drugs. Initially, liquid medication (liquid drug or drug solution or suspension in hydrophilic liquid vehicle) is transformed to free-flowing, non-sticky, compressible powder by the addition of suitable carrier material and coating materials for the development of liquisolid compacts. The postulated mechanism for enhanced solubility was improved wettability of drug and enhanced surface area of molecularly dispersed drug in the liquid environment. Pre- and post-the compression tests were performed for the developed liquisolid compacts to obtain optimized formulation. For the optimized compacts, FTIR and DSC studies were performed for determining drug-excipient compatibility; SEM and PXRD studies were performed to study the solid-state characterization. Furthermore, accelerated stability studies were performed for optimized liquisolid compacts for 6 months according to ICH guidelines and the results were compared with freshly prepared formulations. In conclusion, liquisolid compact formulation was proved to be safe, economic and alternative approach to formulate solid oral dosage forms of poorly aqueous soluble drugs.
3
Kumar, Keshav, Dr Rupali Sharma, Dr Satish Sardana, Mr Shekhar Sharma, and Dr M. Aamir Mirza. "DOSAGE FORM DESIGN." In Futuristic Trends in Pharmacy & Nursing Volume 3 Book 14, 79–84. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bkpn14p1ch6.
Анотація:
The design of dosage forms is a pivotal endeavour within the realm of pharmaceutical sciences, encompassing the intricate interplay between active pharmaceutical ingredients (APIs) and formulation components to achieve optimal therapeutic outcomes. This chapter delves into the multifaceted landscape of dosage form design, exploring the nuanced considerations that underpin the creation of effective, safe, and patient-centric drug delivery systems. Commencing with an introduction to dosage forms, the chapter elucidates the critical role they play in pharmaceuticals, encapsulating a diverse spectrum of solid, liquid, semi-solid, and gaseous entities. Fundamental physicochemical principles governing solubility, dissolution kinetics, and particle characteristics are expounded, providing a foundation for the subsequent design strategies. A comprehensive exploration of drug excipients and formulation components ensues, accentuating their significance in tailoring drug release, stability, and bioavailability. The intricate artistry of solid dosage forms, including tablets and capsules, is deconstructed, encompassing formulation intricacies, compression techniques, and coating methodologies. Liquid dosage forms, from solutions to suspensions, are scrutinized for their formulation challenges and stability considerations, while semi-solid entities such as creams, ointments, and transdermal patches are dissected for their diverse applications. Intriguing forays into parenteral and gaseous dosage forms reveal the precision demanded by injectable solutions, suspensions, and inhalation aerosols. A meticulous evaluation of dosage form attributes is presented, illuminating the role of in vitro dissolution testing, stability studies, and bioavailability assessments. Biopharmaceutics and pharmacokinetics are intricately woven into the narrative, unravelling the influence of dosage form design on drug absorption, distribution, metabolism, and excretion. Nurturing an appreciation for regulatory imperatives, the chapter underscores the alignment of dosage form design with stringent guidelines and standards. Furthermore, emerging trends in the field, including nanotechnology's impact on drug delivery and the advent of personalized medicine, are showcased, offering a glimpse into the evolving landscape of pharmaceutical innovation. In summation, the "Dosage Form Design" chapter unveils the symphony of art and science that orchestrates the creation of dosage forms, fostering an understanding of the pivotal factors governing their design, development, and evaluation. It stands as a testament to the collaborative efforts of pharmaceutical scientists, chemists, engineers, and regulatory experts in crafting pharmaceutical formulations that optimize therapeutic potential while safeguarding patient well-being.
Тези доповідей конференцій з теми "Solutions solides – Stabilité – Solubilité":
1
Rautiola, Davin, and Ronald A. Siegel. "Nasal Spray Device for Administration of Two-Part Drug Formulations." In 2019 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/dmd2019-3216.
Анотація:
Intranasal drug delivery is an attractive route to noninvasively achieve a rapid therapeutic effect, avoid first pass metabolism, and bypass the blood brain barrier. However, the types of drugs that can be administered by this route has been limited, in part, by device technology. Herein, we describe a pneumatic nasal spray device that is capable of mixing liquid and solid components of a drug formulation as part of the actuation process during dose administration. The ability to store a nasal spray drug formulation as two separate components can be leveraged to solve a variety of stability issues that would otherwise preclude intranasal administration. Examples of drugs that could be delivered intranasally by utilizing this two-part formulation strategy include biomolecules that are unstable in solution and low solubility drugs that can be rendered into metastable supersaturated solutions. A proof of concept nasal spray device prototype was constructed to demonstrate that a liquid and solid can be rapidly mixed and atomized into a spray in a single action. The primary breakup distance and angle of the spray cone were measured as a function of the function of the propellant gas pressure.
2
Branagan, D., J. Buffa, and M. Maston. "Advanced Nanoscale Neutron Absorber Coatings for Safe Longterm Storage of Spent Nuclear Fuel and Nuclear Waste." In ITSC2005, edited by E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p0551.
Анотація:
Abstract Neutron absorbers are expected to play an important role in the long-term storage of spent nuclear fuels and nuclear wastes. High neutron absorbing capability, long-term stability, and the capacity to stay with the fuel are important criteria in preventing critical conditions during possible waste package degradation in geological time frames. Existing available neutron absorbing materials are based on boron or boron-10 isotope modifications of austenitic stainless steels or to aluminum based metal matrix composites. Specific rare earths such as gadolinium, samarium, or europium are found to have much higher thermal neutron cross section than boron or boron-10 but have high reactivity which limit their stability and ultimate applicability. In this paper, it is described how it is possible through a nanotechnology approach, to overcome the solubility and stability limitations of conventional materials to allow incorporation of high amounts of boron and rare earths into advanced HVOF coatings. During the development of the NeutraShieldTM Coatings, it was found that high fractions of rare earth elements such as gadolinium along with high concentrations of boron could be dissolved in the liquid melt and then remain soluble in the metallic glass structure. During the transformation of the glass to the nanocomposite structure, the rare earths are found to come out of supersaturated solid solution to form stable nanoscale ternary intermetallic R2Fe14B phases which form in a commensurate fashion and is protected by the highly noble matrix. Abstract only; no full-text paper available.
3
Khan, Md Ashraful Islam, Iván Darío Piñerez Torrijos, Saja Hussam Aldeen Algazban, Skule Strand, and Tina Puntervold. "Polysulphate: A New Eor Additive to Maximize the Oil Recovery from Carbonate Reservoirs at High Temperature." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211443-ms.
Анотація:
Abstract Seawater injection is an EOR success in the North Sea carbonate reservoirs due to wettability alteration toward a more water-wet state, this process is triggered by the difference in composition between injection and formation water. "Smart Water" with optimized ionic composition can be easily made under laboratory conditions to improve oil recovery beyond that of seawater, however, in the field, its preparation may require specific water treatment processes, e.g., desalination, nano-filtration or addition of specific salts. In this work, a naturally occurring salt called polysulphate (PS) is investigated as an additive to produce Smart Water. Outcrop chalk from Stevns Klint, consisting of 98% biogenic CaCO3, was used to investigate the potential and efficiency of the polysulphate brines to alter wettability in chalk. Solubility of polysulphate in seawater and de-ionized water and brine stability at high temperatures were measured. Energy Dispersive X-Ray and ion chromatography were used to determine the composition of the polysulphate salt and EOR-solutions, and to evaluate the sulphate adsorption on the chalk surface, a catalyst for the wettability alteration process. Spontaneous imbibition, for evaluating wettability alteration, of polysulphate brines into mixed-wet chalk was performed at 90 and 110°C and compared against the recovery performance of formation water and seawater. The solubility tests showed that the salt was easily soluble in both de-ionized water and seawater with less than 5% solid residue. The de-ionized polysulphate brine contained sulphate and calcium ion concentration of 31.5 millimolar (mM) and 15.2 mM, respectively, and total salinity was 4.9 g/L. This brine composition is very promising for triggering wettability alteration in chalk. The seawater polysulphate brine contained 29.6 mM calcium ions and 55.9 mM sulphate ions, and a total salinity of 38.1 g/L. Compared to ordinary seawater this brine has the potential for improved wettability alteration in chalk due to increased sulphate content. Ion chromatography revealed that the sulphate adsorbed when polysulphate brines were flooded through the core, which is an indication that wettability alteration can take place during brine injection, the reactivity was also enhanced by increasing the temperature from 25 to 90 °C. Finally, the oil recovery tests by spontaneous imbibition showed that polysulphate brines were capable of inducing wettability alteration, improving oil recovery beyond that obtained by formation water injection. The difference in oil recovery between ordinary seawater and seawater polysulphate injection was smaller due to the already favorable composition of seawater. Polysulphate brines showed a significant potential for wettability alteration in carbonates and are validated as a potential EOR additives for easy and on-site preparation of Smart Water brines for carbonate oil reservoirs. Polysulphate salt, added to the EOR-solution, provides the essential ions for the wettability alteration process, but further optimization is needed to characterize the optimal mixing ratios, ion compositions, and temperature ranges at which EOR effects can be achieved.