Log in

Relevant bibliographies by topics / Polymorphic transformations / Journal articles

Journal articles on the topic 'Polymorphic transformations'

To see the other types of publications on this topic, follow the link: Polymorphic transformations.

Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Polymorphic transformations.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Khoj, Manal A., Colan E. Hughes, Kenneth D. M. Harris, and Benson M. Kariuki. "Polymorphic phase transformations of 3-chloro-trans-cinnamic acid and its solid solution with 3-bromo-trans-cinnamic acid." Acta Crystallographica Section C Structural Chemistry 74, no. 8 (July 13, 2018): 923–28. http://dx.doi.org/10.1107/s2053229618009269.

Full text

Abstract:

We have investigated the polymorphic phase transformations above ambient temperature for 3-chloro-trans-cinnamic acid (3-ClCA, C9H7ClO2) and a solid solution of 3-ClCA and 3-bromo-trans-cinnamic acid (3-BrCA, C9H7BrO2). At 413 K, the γ polymorph of 3-ClCA transforms to the β polymorph. Interestingly, the structure of the β polymorph of 3-ClCA obtained in this transformation is different from the structure of the β polymorph of 3-BrCA obtained in the corresponding polymorphic transformation from the γ polymorph of 3-BrCA, even though the γ polymorphs of 3-ClCA and 3-BrCA are isostructural. We also report a high-temperature phase transformation from a γ-type structure to a β-type structure for a solid solution of 3-ClCA and 3-BrCA (with a molar ratio close to 1:1). The γ polymorph of the solid solution is isostructural with the γ polymorphs of pure 3-ClCA and pure 3-BrCA, while the β-type structure produced in the phase transformation is structurally similar to the β polymorph of pure 3-BrCA.

APA, Harvard, Vancouver, ISO, and other styles

2

Takeguchi, Seiya, Arisa Sato, Hironori Hondoh, Mio Aoki, Hidetaka Uehara, and Satoru Ueno. "Multiple β Forms of Saturated Monoacid Triacylglycerol Crystals." Molecules 25, no. 21 (November 2, 2020): 5086. http://dx.doi.org/10.3390/molecules25215086.

Full text

Abstract:

We have investigated the polymorphism of triacylglycerol (TAG) crystals as they affect the qualities such as shelf life, mouth feel, and texture of chocolate and other products. Saturated monoacid TAGs, like trilaurin, are considered as models for TAG crystallization; however, there is still debate about the number of their polymorphs that exist. In this study, we characterized a set of novel polymorphs, β forms of saturated monoacid TAGs, which were obtained via different pathways depending on the crystallization history, by polarized light microscopy, X-ray diffraction, and differential scanning calorimetry. Saturated monoacid TAGs were crystallized as the unstable polymorphs, the α or β’ forms first, and then they were transformed into β forms by solid–solid transformations. The β form that had transformed from β’ changed its morphology by a polymorphic transformation, while the β form made from the α form kept its spherulite morphology. The β forms obtained showed different melting points. Additional heat treatment promoted further polymorphic transformation. Four novel β forms were found for each of the saturated monoacid TAGs, trilaurin, trimyristin, tripalmitin, and tristearin. They showed similar polymorphism with the same subcell packing.

APA, Harvard, Vancouver, ISO, and other styles

3

Kinelovskii S.A. "Similarity between shock-induced polymorphic transitions in the silica system." Technical Physics 92, no. 6 (2022): 695. http://dx.doi.org/10.21883/tp.2022.06.54415.320-21.

Full text

Abstract:

A set of experimental data on the thermodynamic parameters of polymorphic transitions in the silica system is considered. Analysis of these parameters in dimensionless form is performed. A fundamental result of the analysis is that the thermodynamic parameters of all silica polymorphs after transitions are described by a single universal Hugoniot of polymorphic transition. It is shown that the two-shock model of polymorphic transformations proposed earlier by the author describes all the results obtained in the analysis. A joint consideration of the experimental data and model calculations leads to the conclusion that during a polymorphic transformation, the density of the new phase is determined from the condition that the elastic pressure components after the first shock and after the polymorphic transition are equal. Keywords: silica, quartz, coesite, stishovite, fused quartz, quartz ceramic, polymorphic transformation, similarity, Hugoniot.

APA, Harvard, Vancouver, ISO, and other styles

4

Spivak L. V., Kirchanov V. S., and Shchepina N. E. "Polymorphic transformations in iodine titanium." Physics of the Solid State 64, no. 11 (2022): 1784. http://dx.doi.org/10.21883/pss.2022.11.54208.400.

Full text

Abstract:

Based on the analysis of differential scanning calorimetry data, the possibility of classifying the observed endothermic or exothermic transformations as phase transformations of the first oder is considered. Two approaches have been implemented. The first is based on the correspondence between the temperatures of the maximum conversion rate and the temperatures of the extrema on the second derivative of the differential scanning calorimetry signal with respect to temperature. In the second approach, the phase transformation is considered as a kind of kinetic reaction of a chemical process with the determination of some parameters included in the kinetic equations. In this case, the order parameter of such reaction n is obtained from the analysis of the differential scanning calorimetry signal shape in the region of phase transformation registration temperatures. Using the example of experiments carried out during thermal cycling of titanium iodide samples, it is shown that both the first and second approaches make it possible to fairly adequately attribute the processes that cause calorimetric effects on the dependences of differential scanning calorimetry to first-order phase transitions. In particular, the obtained results of differential scanning calorimetry during heating and cooling of iodide titanium show that polymorphic transformations in it are realized by various mechanisms depending on the rate of thermal cycling and the thermal history of the metal. Keywords: activation energy, titanium, calorimetry, polymorphism, structure, approximation.

APA, Harvard, Vancouver, ISO, and other styles

5

Кинеловский, С. А. "Подобие ударно-волновых полиморфных переходов в системе кремнезема." Журнал технической физики 92, no. 6 (2022): 822. http://dx.doi.org/10.21883/jtf.2022.06.52511.320-21.

Full text

Abstract:

A set of experimental data on the thermodynamic parameters of polymorphic transitions in the silica system is considered. Analysis of these parameters in dimensionless form is performed. A fundamental result of the analysis is that the thermodynamic parameters of all silica polymorphs after transitions are described by a single universal Hugoniot of polymorphic transition. It is shown that the two-shock model of polymorphic transformations proposed earlier by the author describes all the results obtained in the analysis. A joint consideration of the experimental data and model calculations leads to the conclusion that during a polymorphic transformation, the density of the new phase is determined from the condition that the elastic pressure components after the first shock and after the polymorphic transition are equal.

APA, Harvard, Vancouver, ISO, and other styles

6

Lapina, Yu T., A. S. Savitskii, E. V. Motina, N. V. Bychin, A. A. Lobanova, and N. I. Golovina. "Polymorphic transformations of hexanitrohexaazaisowurtzitane." Russian Journal of Applied Chemistry 82, no. 10 (October 2009): 1821–28. http://dx.doi.org/10.1134/s1070427209100140.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Kuzmin, V. S., V. V. Chernyshev, and A. I. Luttseva. "X-RAY POWDER DIFFRACTION IN QUALITY CONTROL OF MEDICINES." Bulletin of the Scientific Centre for Expert Evaluation of Medicinal Products 8, no. 3 (September 26, 2018): 158–61. http://dx.doi.org/10.30895/1991-2919-2018-8-3-158-161.

Full text

Abstract:

X-ray powder diffraction is one of the methods used for detection and analysis of polymorphic forms of pharmaceutical substances. The article elucidates the concept of polymorphism, briefly explains physical characteristics of this phenomenon, conditions of polymorphic transformations and the prevalence of polymorphic forms among drug substances. It should be noted that polymorphism is observed in drug substances belonging to different pharmacologic classes. Polymorphic forms of the same drug substance have different solubility, melting point, resistance to oxidation and to other destructive processes, and, consequently, different surface properties which affect both the rate of absorption of the drug substances and their stability as components of dosage forms. This calls for the need to control the quality of drug substances for potential presence of polymorphic forms. The use of diffraction methods for examination of cryomodified forms of various biologically active compounds obtained by evaporation and subsequent precipitation at low temperatures resulted in obtaining polycrystalline substances with new properties. The article provides results of examination of crystalline modifications of phenazepam in the form of α- and β-polymorphs, tilorone, fabomotizole, zolendronic acid and dehydroepiandrosterone. It was demonstrated that the use of X-ray diffraction analysis for examination and quality control of polymorphic forms of drugs is a necessary component of identification testing.

APA, Harvard, Vancouver, ISO, and other styles

8

L. V. Spivak and N.E. Shchepina. "Features of polymorphic transformation during heating and cooling of cobalt." Technical Physics 92, no. 4 (2022): 478. http://dx.doi.org/10.21883/tp.2022.04.53604.295-21.

Full text

Abstract:

Differential scanning calorimetry was used to study the regularities of polymorphic α↔β-transformation in polycrystalline cobalt. The value of the activation energy of the α->β-transformation during heating of cobalt (290-50 kJ/mol), enthalpy and entropy, depending on the thermal history of the metal, is determined. It is shown that the mechanisms of recrystallization under heating are closer to the first-order I phase transformations. When cooling under conditions of limited diffusion mobility of cobalt atoms, recrystallization is apparently carried out due to the passage of several diffusion-free mechanisms of phase transformation, implemented in close temperature ranges. Keywords: activation energy, cobalt, calorimetry, polymorphism, enthalpy, entropy.

APA, Harvard, Vancouver, ISO, and other styles

9

Blagden, N. "Monitoring polymorphic transformations in solution." Acta Crystallographica Section A Foundations of Crystallography 61, a1 (August 23, 2005): c438. http://dx.doi.org/10.1107/s0108767305081602.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Estrin, E. I. "Kinetic modes of polymorphic transformations." Journal de Physique IV (Proceedings) 112 (October 2003): 41–49. http://dx.doi.org/10.1051/jp4:2003838.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Sato, K. "Polymorphic transformations in crystal growth." Journal of Physics D: Applied Physics 26, no. 8B (August 14, 1993): B77—B84. http://dx.doi.org/10.1088/0022-3727/26/8b/011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Chan, S. K. "The polymorphic transformations of zirconia." Physica B+C 150, no. 1-2 (May 1988): 212–22. http://dx.doi.org/10.1016/0378-4363(88)90124-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Kiš, E. E., G. A. Lomić, G. C. Bošković, and R. P. Marinković-Nedučin. "Accelerated polymorphic transformations of alumina." Reaction Kinetics and Catalysis Letters 63, no. 2 (March 1998): 323–28. http://dx.doi.org/10.1007/bf02475406.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Boulfelfel, Salah Eddine, Daniele Selli, and Stefano Leoni. "Mechanism of Polymorphic Transformations in the Chemical Elements." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1536. http://dx.doi.org/10.1107/s2053273314084630.

Full text

Abstract:

The prediction of a crystal structure at given composition and thermodynamic coupling parameters is a major challenge. Powerful methods have boosted progress in this field, recently, and have promoted this are of research into a multidisciplinary one. The capacity of anticipating the outcome of a synthetic effort, or the search for novel materials with distinct, improved properties greatly benefit from numerical methods able to efficiently scan for novel structural motifs. Several techniques based on evolutionary algorithms, metadynamics, random structure prediction, or transition path sampling are contributing important advances in the understanding of polymorphic transformation, and are enriching the catalogue of crystalline matter by surprising novel packings [1]. One of the central aspects to fully unfold the impact of crystal structure prediction is the elucidation of transformation mechanisms, which are productive towards a particular structural motif under experiment-relavant conditions. In the recent dispute on the structural identity of the product of graphite cold compression, the true product was confirmed to be Oganov's M-Carbon by applying transition path sampling [2]. While many carbon polymorphs can exist in principle, kinetic control will typically select a particular mechanism of formation of a distinct carbon. This proves that, while the enumeration of crystal structures is invaluable in discovering novel material with improved properties, and in exploring novel compositions, it is important to associate a mechanism with the formation of a particular structure, for a realistic crystal structure prediction, one that can be turned into a real material. The talk will have a review character, and will touch upon recent results in the filed of the polymorphism of the elements and binary semiconductors [3].

APA, Harvard, Vancouver, ISO, and other styles

15

Talis, Alexander, and Valentin Kraposhin. "Finite noncrystallographic groups, 11-vertex equi-edged triangulated clusters and polymorphic transformations in metals." Acta Crystallographica Section A Foundations and Advances 70, no. 6 (October 2, 2014): 616–25. http://dx.doi.org/10.1107/s2053273314015733.

Full text

Abstract:

The one-to-one correspondence has been revealed between a set of cosets of the Mathieu groupM11, a set of blocks of the Steiner systemS(4, 5, 11) and 11-vertex equi-edged triangulated clusters. The revealed correspondence provides the structure interpretation of theS(4, 5, 11) system: mapping of the biplane 2-(11, 5, 2) onto the Steiner systemS(4, 5, 11) determines uniquely the 11-vertex tetrahedral cluster, and the automorphisms of theS(4, 5, 11) system determine uniquely transformations of the said 11-vertex tetrahedral cluster. The said transformations correspond to local reconstructions during polymorphic transformations in metals. The proposed symmetry description of polymorphic transformation in metals is consistent with experimental data.

APA, Harvard, Vancouver, ISO, and other styles

16

Спивак, Л. В., and Н. Е. Щепина. "Особенности полиморфных превращений в железе и цирконии." Журнал технической физики 90, no. 7 (2020): 1145. http://dx.doi.org/10.21883/jtf.2020.07.49449.381-19.

Full text

Abstract:

Features of the polymorphic transformations in iron of different purity and zirconium iodide were studied using high-resolution calorimetry methods. It has been suggested that the polymorphic transformations in zirconium, in contrast to the polymorphic transformations in iron, were controlled by two mechanisms: diffusion-free and diffusion. The relationship between them depends on the rate of thermal cycling and the thermal background of zirconium.

APA, Harvard, Vancouver, ISO, and other styles

17

Tschauner, Oliver. "Corresponding States for Volumes of Elemental Solids at Their Pressures of Polymorphic Transformations." Crystals 12, no. 12 (November 23, 2022): 1698. http://dx.doi.org/10.3390/cryst12121698.

Full text

Abstract:

Many non-molecular elemental solids exhibit common features in their structures over the range of 0 to 0.5 TPa that have been correlated with equivalent valence electron configurations. Here, it is shown that the pressures and volumes at polymorphic transitions obey corresponding states given by a single, empirical universal step-function Vtr/L = −0.0208(3) · Ptr + Ni, where Vtr is the atomic volume in Å3 at a given transformation pressure Ptr in GPa, and L is the principal quantum number. Ni assumes discrete values of approximately 20, 30, 40, etc. times the cube of the Bohr radius, thus separating all 113 examined polymorphic elements into five discrete sets. The separation into these sets is not along L. Instead, strongly contractive polymorphic transformations of a given elemental solid involve changes to different sets. The rule of corresponding states allows for predicting atomic volumes of elemental polymorphs of hitherto unknown structures and the transitions from molecular into non-molecular phases such as for hydrogen. Though not an equation of state, this relation establishes a basic principle ruling over a vast range of simple and complex solid structures that confirms that effective single-electron-based calculations are good approximations for these materials and pressures The relation between transformation pressures and volumes paves the way to a quantitative assessment of the state of very dense matter intermediate between the terrestrial pressure regime and stellar matter.

APA, Harvard, Vancouver, ISO, and other styles

18

Молодец, А. М., А. А. Голышев, А. Н. Емельянов, and А. А. Козлов. "Магнитные превращения и полиморфный переход ферромагнитных сталей при ударно-волновом нагружении." Журнал технической физики 91, no. 5 (2021): 803. http://dx.doi.org/10.21883/jtf.2021.05.50692.263-20.

Full text

Abstract:

A.M. Molodets A.A. Golyshev, A.N. Emelyanov, A.A. Kozlov The method for recording magnetic transformation is presented for ferromagnetic steels under shock-wave loading. The operation of the magnetic transformation gauge is considered under shock-wave loading at the polymorphic transition pressure of ARMCO iron and 15Kh2NMFA (in Russian) nuclear reactors case steel. It is shown that the pressures of magnetic transformations of steels correlate with the pressures of polymorphic transitions of these shocked steels. Comparison of gauge readings and parameters of polymorphic transitions was performed for iron and steel during shock-wave compression and subsequent unloading

APA, Harvard, Vancouver, ISO, and other styles

19

Молодец, А. М., А. А. Голышев, А. Н. Емельянов, and А. А. Козлов. "Магнитные превращения и полиморфный переход ферромагнитных сталей при ударно-волновом нагружении." Журнал технической физики 91, no. 5 (2021): 803. http://dx.doi.org/10.21883/jtf.2021.05.50692.263-20.

Full text

Abstract:

A.M. Molodets A.A. Golyshev, A.N. Emelyanov, A.A. Kozlov The method for recording magnetic transformation is presented for ferromagnetic steels under shock-wave loading. The operation of the magnetic transformation gauge is considered under shock-wave loading at the polymorphic transition pressure of ARMCO iron and 15Kh2NMFA (in Russian) nuclear reactors case steel. It is shown that the pressures of magnetic transformations of steels correlate with the pressures of polymorphic transitions of these shocked steels. Comparison of gauge readings and parameters of polymorphic transitions was performed for iron and steel during shock-wave compression and subsequent unloading

APA, Harvard, Vancouver, ISO, and other styles

20

Chatziadi, Argyro, Eliška Skořepová, Jan Rohlíček, Michal Dušek, Luděk Ridvan, and Miroslav Šoóš. "Mechanochemically Induced Polymorphic Transformations of Sofosbuvir." Crystal Growth & Design 20, no. 1 (November 5, 2019): 139–47. http://dx.doi.org/10.1021/acs.cgd.9b00922.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Spivak, L. V., and N. E. Shchepina. "Polymorphic Transformations in Iron and Zirconium." Technical Physics 65, no. 7 (July 2020): 1100–1105. http://dx.doi.org/10.1134/s1063784220070221.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Yaokawa, Ritsuko, Akihiro Nagoya, and Hideyuki Nakano. "Polymorphic transformations of CaSi2 and CaGe2." Journal of Solid State Chemistry 295 (March 2021): 121919. http://dx.doi.org/10.1016/j.jssc.2020.121919.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Fertman, Elena L., Alexey V. Fedorchenko, Erik Čižmár, Serhii Vorobiov, Alexander Feher, Yury V. Radyush, Anatoli V. Pushkarev, et al. "Magnetic Diagram of the High-Pressure Stabilized Multiferroic Perovskites of the BiFe1-yScyO3 Series." Crystals 10, no. 10 (October 17, 2020): 950. http://dx.doi.org/10.3390/cryst10100950.

Full text

Abstract:

Magnetic properties of the high-pressure stabilized perovskite BiFe1-yScyO3 phases (0.1 ≤ y ≤ 0.9) have been studied by means of magnetization measurements and neutron diffraction. The metastable perovskites of this series undergo irreversible polymorphic transformations upon annealing, the phenomenon referred to as conversion polymorphism. It has been found that the solid solutions with y ≥ 0.70 exhibit no long-range magnetic ordering regardless of their polymorph modification, while those with y ≤ 0.60 are all antiferromagnets. Depending on the scandium content, temperature and structural distortions, three types of the antiferromagnetic orderings, involving collinear, canted and cycloidal spin arrangements, have been revealed in the phases obtained via conversion polymorphism and the corresponding magnetic phase diagram has been suggested.

APA, Harvard, Vancouver, ISO, and other styles

24

Ghazani, Saeed M., and Alejandro G. Marangoni. "Molecular Origins of Polymorphism in Cocoa Butter." Annual Review of Food Science and Technology 12, no. 1 (March 25, 2021): 567–90. http://dx.doi.org/10.1146/annurev-food-070620-022551.

Full text

Abstract:

Cocoa butter displays complex crystallization behavior and six crystal polymorphic forms. Although the crystal structure of cocoa butter has been studied extensively, the molecular interactions between cocoa butter triacylglycerols in relation to polymorphic transformations from metastable forms (forms III and IV) to stable crystal forms (forms V and VI) remain largely unknown. In this review, the triclinic polymorphism and melting profiles of the major triacylglycerols in cocoa butter—POP, POS, and SOS—are reviewed, and their binary and ternary phase behaviors in metastable (pseudoβ′) and stable (β2) crystal forms are discussed. We also attempt to clarify how the transformation of cocoa butter from form IV to V, as a critical step in the tempering of chocolate, is controlled by POS interactions with both POP and SOS. Moreover, we show how the crystal forms V and VI of cocoa butter are templated by crystal forms β3 and β1 of POS, respectively.

APA, Harvard, Vancouver, ISO, and other styles

25

Makudera, A. O., and S. M. Lakiza. "Interaction in the systems Y2O3−Ln2O3 (Ln=Tb–Lu)." Uspihi materialoznavstva 2021, no. 2 (June 1, 2021): 72–78. http://dx.doi.org/10.15407/materials2021.02.072.

Full text

Abstract:

Based on the analysis of literature data from experimentally constructed phase diagrams of Y2O3 − Ln2O3 systems (Ln = Tb − Lu), as well as temperatures of polymorphic transformations of rare earth oxides (REE), tentative phase diagrams of Y2O3 − Ln2O3 systems (Ln = Tb − Lu) were constructed in wide intervals of temperatures and concentrations. Prediction of the binary phase diagrams structure of yttria − yttrium subgroup lanthanides systems was carried out on the basis of three principles: 1. Since double systems are formed by lanthanide oxides of one (yttrium) subgroup, it is very likely that in such systems continuous solid solutions will be formed between the components. 2. Intermediate binary phases are not formed in these systems. 3. The formation of continuous solid solutions occurs with a decrease in the temperatures of phase transformations in the solid state to a minimum shifted towards a lower transformation temperature of the system component. The forecast of the Y2O3 – Ln2O3 systems phase diagrams structure, where Ln = Tb – Lu, indicates the complete solubility of the components in the liquid and solid states. Binary compounds in the considered systems are not predicted. Phase transformations in the solid solutions on the basis of polymorphic modifications X, H, A, B and C of lanthanide oxides cascade at high temperatures by the peritectoid mechanism. Below 1850 °C regions of solid solutions with cubic C-structure of REE oxides are formed in the whole range of concentrations in the systems. Key words: REE oxides, yttria, polymorphs of REE oxides, phase diagram.

APA, Harvard, Vancouver, ISO, and other styles

26

Guan, Rongfeng, Pan Wang, Yang Song, and Viktor N. Staroverov. "Pressure-Induced Polymorphic Transformations of Ethylenediamine Bisborane." Journal of Physical Chemistry C 125, no. 34 (August 19, 2021): 18614–22. http://dx.doi.org/10.1021/acs.jpcc.1c05593.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Rakov, L. T., and V. T. Dubinchuk. "Structural defects and polymorphic transformations in quartz." Geochemistry International 50, no. 8 (July 26, 2012): 671–82. http://dx.doi.org/10.1134/s0016702912060067.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Nasirov, V. I., R. B. Bairamov, and E. V. Nasirov. "Polymorphic Transformations in the K0.945Ag0.055NO3 Single Crystal." Crystallography Reports 65, no. 2 (March 2020): 309–13. http://dx.doi.org/10.1134/s1063774520020169.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Gorkovenko, Ekaterina A., Sergey E. Kichanov, Denis P. Kozlenko, Alexandr V. Belushkin, Jan Wąsicki, Wojciech Nawrocik, Jadwiga Mielcarek, Leonid S. Dubrovinsky, Christian Lathe, and Boris N. Savenko. "The Pressure-Induced Polymorphic Transformations in Fluconazole." Journal of Pharmaceutical Sciences 104, no. 12 (December 2015): 4164–69. http://dx.doi.org/10.1002/jps.24644.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Kawakami, Kohsaku. "Reversibility of Enantiotropically Related Polymorphic Transformations from a Practical Viewpoint: Thermal Analysis of Kinetically Reversible/Irreversible Polymorphic Transformations." Journal of Pharmaceutical Sciences 96, no. 5 (May 2007): 982–89. http://dx.doi.org/10.1002/jps.20748.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Walvekar, P. M. "POLYMORPHIC STUDIES OF FLUCONAZOLE IN DIFFERENT CRYSTAL SOLVATE FORMS AND ITS IMPLICATION ON BCS SOLUBILITY AND DISSOLUTION." INDIAN DRUGS 55, no. 05 (May 28, 2018): 31–36. http://dx.doi.org/10.53879/id.55.05.10964.

Full text

Abstract:

Fluconazole (anhydrate) is an anti-fungal agent which exists in various polymorphic forms. The present study is an attempt to obtain crystal solvates of fluconazole using various solvents and study its effect on polymorphic transformation and its implication on solubility and dissolution. fluconazole exhibits polymorphism and is poorly soluble in water, hence attempt was made to improve its solubility and dissolution. Crystal solvates of fluconazole were prepared in different solvents viz acetonitrile, methanol, propan-2-d and n-butanol. Polymorphic transformations were ascertained by subjecting the crystal solvates of fluconazole to BCS solubility, dissolution, FTIR, optical microscopy, DSC, SEM and X-ray powder diffraction (XRPD). Results indicated that the crystal solvates of propan-2-ol exhibited improved solubility and dissolution compared to other crystal solvates and pure drug. BCS based intrinsic solubility studies revealed that crystal solvates of propan-2-ol exhibited highest solubility at pH 1.2. FTIR studies revealed that the functional groups of fluconazole were found to be unaltered. Optical microscopy and scanning electron microscopy studies revealed morphological changes of crystal solvates, which indicates polymorphic changes of fluconazole. DSC of crystal solvates obtained from propan-2-ol revealed change to hydrate form, whereas XRPD study revealed crystal solvates of propan-2-ol were more crystalline in nature when compared with that of the pure drug.

APA, Harvard, Vancouver, ISO, and other styles

32

Wright, James S., Iñigo J. Vitórica-Yrezábal, Harry Adams, Stephen P. Thompson, Adrian H. Hill, and Lee Brammer. "Solvent-vapour-assisted pathways and the role of pre-organization in solid-state transformations of coordination polymers." IUCrJ 2, no. 2 (February 26, 2015): 188–97. http://dx.doi.org/10.1107/s2052252515000147.

Full text

Abstract:

A family of one-dimensional coordination polymers, [Ag4(O2C(CF2)2CF3)4(phenazine)2(arene)n]·m(arene),1(arene = toluene or xylene), have been synthesized and crystallographically characterized. Arene guest loss invokes structural transformations to yield a pair of polymorphic coordination polymers [Ag4(O2C(CF2)2CF3)4(phenazine)2],2aand/or2b, with one- and two-dimensional architectures, respectively. The role of pre-organization of the polymer chains of1in the selectivity for formation of either polymorph is explored, and the templating effect of toluene andp-xylene overo-xylene orm-xylene in the formation of arene-containing architecture1is also demonstrated. The formation of arene-free phase2b, not accessible in a phase-pure form through other means, is shown to be the sole product of loss of toluene from1-tol·tol[Ag4(O2C(CF2)2CF3)4(phenazine)2(toluene)]·2(toluene), a phase containing toluene coordinated to Ag(I) in an unusual μ:η1,η1manner. Solvent-vapour-assisted conversion between the polymorphic coordination polymers and solvent-vapour influence on the conversion of coordination polymers1to2aand2bis also explored. The transformations have been examined and confirmed by X-ray diffraction, NMR spectroscopy and thermal analyses, includingin situdiffraction studies of some transformations.

APA, Harvard, Vancouver, ISO, and other styles

33

Tian, Beiqian, Zhiyong Ding, Shuyi Zong, Jinyue Yang, Na Wang, Ting Wang, Xin Huang, and Hongxun Hao. "Manipulation of Pharmaceutical Polymorphic Transformation Process Using Excipients." Current Pharmaceutical Design 26, no. 21 (June 24, 2020): 2553–63. http://dx.doi.org/10.2174/1381612826666200213122302.

Full text

Abstract:

Background: In the pharmaceutical field, it is vital to ensure a consistent product containing a single solid-state form of the active pharmaceutical ingredient (API) in the drug product. However, some APIs are suffering from the risk of transformation of their target forms during processing, formulation and storage. Methods: The purpose of this review is to summarize the relevant category of excipients and demonstrate the availability and importance of using excipients as a key strategy to manipulate pharmaceutical polymorphic transformation. Results: The excipient effects on solvent-mediated phase transformations, solid-state transitions and amorphous crystallization are significant. Common pharmaceutical excipients including amino acids and derivatives, surfactants, and various polymers and their different manipulation effects were summarized and discussed. Conclusion: Appropriate use of excipients plays a role in manipulating polymorphic transformation process of corresponding APIs, with a promising application of guaranteeing the stability and effectiveness of drug dosage forms.

APA, Harvard, Vancouver, ISO, and other styles

34

Aliyev, Y. I., Y. G. Asadov, R. D. Aliyeva, T. G. Naghiyev, and S. H. Jabarov. "Influence of partial substitution of Cu atoms by Zn and Cd atoms on polymorphic transformation in the Cu1.75Te crystal." Modern Physics Letters B 33, no. 11 (April 18, 2019): 1850128. http://dx.doi.org/10.1142/s0217984919501288.

Full text

Abstract:

The [Formula: see text], [Formula: see text] and [Formula: see text] compounds have been synthesized and low-temperature modification single crystals obtained from the high temperature modification by polymorphic transformation. The method of high temperature X-ray diffractometer has been used to study [Formula: see text] (x = 0.05 Zn and Cd) layered single crystal. It was established that such a substitution has a significant impact on the number and temperature of polymorphic transformations. Crystallgraphic parameters were determined for each phase. Temperature dependence of lattice parameters were obtained and determined change mechanism of lattice parameters by influence of temperature.

APA, Harvard, Vancouver, ISO, and other styles

35

Belomestnykh, V. N., E. P. Tesleva, and E. G. Soboleva. "Maximal Grüneisen parameter at polymorphic transformations in crystals." Technical Physics 54, no. 2 (February 2009): 320–22. http://dx.doi.org/10.1134/s1063784209020273.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Estrin, E. I. "On the nature of plasticity upon polymorphic transformations." Physics of Metals and Metallography 102, no. 1 (July 2006): 114–19. http://dx.doi.org/10.1134/s0031918x06070167.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Wheaton, Amelia M., Ilia A. Guzei, Caleb Harris, and John F. Berry. "Polymorphic transformations of [Co(μ-OOCtBu)2py]2." Acta Crystallographica Section A Foundations and Advances 75, a1 (July 20, 2019): a90. http://dx.doi.org/10.1107/s0108767319099094.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Kanel’, G. I., G. S. Bezruchko, A. S. Savinykh, S. V. Razorenov, V. V. Milyavskii, and K. V. Khishchenko. "Submicrosecond polymorphic transformations accompanying shock compression of graphite." High Temperature 48, no. 6 (December 2010): 806–14. http://dx.doi.org/10.1134/s0018151x10060064.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Keymolen, Bram, James L. Ford, Mark W. Powell, and Ali R. Rajabi-Siahboomi. "Investigation of the polymorphic transformations from glassy nifedipine." Thermochimica Acta 397, no. 1-2 (February 2003): 103–17. http://dx.doi.org/10.1016/s0040-6031(02)00221-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Wei, Rong-Jia, Bao Li, Jun Tao, Rong-Bin Huang, Lan-Sun Zheng, and Zhiping Zheng. "Making Spin-Crossover Crystals by Successive Polymorphic Transformations." Inorganic Chemistry 50, no. 4 (February 21, 2011): 1170–72. http://dx.doi.org/10.1021/ic102231j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Pirouz, P. "On twinning and polymorphic transformations in compound semiconductors." Scripta Metallurgica 23, no. 3 (March 1989): 401–6. http://dx.doi.org/10.1016/0036-9748(89)90390-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Begin-colin, S., G. Le Caer, A. Mocellin, and M. Zandona. "Polymorphic transformations of titania induced by ball milling." Philosophical Magazine Letters 69, no. 1 (January 1994): 1–7. http://dx.doi.org/10.1080/09500839408242430.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Mazeina, L., J. Majzlan, and A. Navrotsky. "Polymorphic transformations of iron oxides: A thermodynamic view." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A406. http://dx.doi.org/10.1016/j.gca.2006.06.818.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Belosludov, Rodion V., Kirill V. Gets, Oleg S. Subbotin, Ravil K. Zhdanov, Yulia Yu Bozhko, Vladimir R. Belosludov, and Jun-ichi Kudoh. "Modeling the polymorphic transformations in amorphous solid ice." Journal of Alloys and Compounds 707 (June 2017): 108–13. http://dx.doi.org/10.1016/j.jallcom.2016.12.197.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Schneider-Rauber, Gabriela, Mihails Arhangelskis, Andrew D. Bond, Raimundo Ho, Nandkishor Nere, Shailendra Bordawekar, Ahmad Y. Sheikh, and William Jones. "Polymorphism and surface diversity arising from stress-induced transformations – the case of multicomponent forms of carbamazepine." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, no. 1 (January 16, 2021): 54–67. http://dx.doi.org/10.1107/s2052520620015437.

Full text

Abstract:

Stress-induced transformations of labile multicomponent organic solids may have a significant impact on industrial manufacturing processes, for example, in the pharmaceutical field. This study considers 15 carbamazepine (CBZ) multicomponent crystal forms, with the aim of identifying the structural and surface features that drive the outcome of thermal stress-induced transformations. Analysis of the crystal structures, and specifically the degree of similarity with the CBZ polymorphs produced by desolvation-like processes, identifies some degree of correlation between structural features. In particular, mutually exclusive supramolecular motifs identified previously within CBZ crystal structures are frequently (but not invariably) preserved, and thereby provide some indication of the anticipated polymorphic outcome. This is broadly consistent with established models relating reactant and product crystal phases. Some of the CBZ multicomponent materials show surface modifications indicative of the formation of a liquid intermediate phase, which provides an alternative dissolution/recrystallization mechanism and different polymorphic outcomes compared to the direct solid–solid transformation pathway. Other cases show intermediates of varying stoichiometry and instances of chemical decomposition. Hence, the product of thermal decomposition is frequently affected by the physical properties of the coformer, such as boiling point and reactivity. This can lead to a dependence on experimental conditions, especially when events such as recrystallization, chemical decomposition of the coformer, solubilization and peritectic melting occur concomitantly. This study highlights that the overall picture is complex, even within this series of closely related materials.

APA, Harvard, Vancouver, ISO, and other styles

46

Purba, Elida. "DETERMINATION OF REACTION KINETICS USING ONLINE X-RAY DIFFRACTION." Indonesian Journal of Chemistry 8, no. 3 (June 17, 2010): 337–41. http://dx.doi.org/10.22146/ijc.21588.

Full text

Abstract:

X-ray diffraction (XRD) is a powerful technique for the study of polymorphism and polymorphic phase transformations. Monitoring of phase transformation directly has been very limited to-date. The XRD system used in this study was used to determine the rate of transformation of pure glutamic acid a form to b form in a solution mediated phase. On every run starting from the pure a form, the transformation process was monitored continuously at fixed temperature, and separate experiments were performed as a function of temperature. The operating temperature was varied from 36 to 57 °C with 10% w/w solid concentration. Data were taken every 200 seconds until the transformation was completed. This paper is concerned with a study of the transformation of the alpha (a) form of L-glutamic acid (L-GA) to the beta (b) form in order to determine the kinetic reaction. The rate constant (k), activation energy (Ea) and pre-exponential factor (A) were obtained. Sensitivity tests were also carried out to examine minimum detection limit when both a and b present in the mixture. In addition, effect of particle size on XRD patterns was also determined. The results show that XRD gives useful information to observe polymorphism for pharmaceutical industry. Keywords: XRD, polymorphism, glutamic acid, reaction kinetics

APA, Harvard, Vancouver, ISO, and other styles

47

Hansen, Steve C., and D. Kobertz. "Solid-State Transformations in Metal Iodides." Solid State Phenomena 138 (March 2008): 29–42. http://dx.doi.org/10.4028/www.scientific.net/ssp.138.29.

Full text

Abstract:

Numerous solid-state transformations occur in metal iodides. These transformations can be classified into three categories: polymorphic transformations, polytypic transitions and molecular solids. Many of the modifications of metal iodides involve metastable phases transforming into stable phases. Revisions to the In-I and Th-I phase diagrams are made based on data found in the literature.

APA, Harvard, Vancouver, ISO, and other styles

48

Ali, Imran, Jiequn Tang, Yanqiang Han, Zhiyun Wei, Yongli Zhang, and Jinjin Li. "A Solid-Solid Phase Transformation of Triclabendazole at High Pressures." Crystals 12, no. 2 (February 21, 2022): 300. http://dx.doi.org/10.3390/cryst12020300.

Full text

Abstract:

Triclabendazole is an effective medication to treat fascioliasis and paragonimiasis parasitic infections. We implemented a reliable quantum mechanical method which is density functional theory at the level of ωB97XD/6-31G* along with embedded fragments to elucidate stability and phase transition between two forms of triclabendazole. We calculated crystal structure parameters, volumes, Gibbs free energies, and vibrational spectra of two polymorphic forms of triclabendazole under different pressures and temperatures. We confirmed form I was more stable than form II at atmospheric pressure and room temperature. From high-pressure Gibbs free energy computations, we found a pressure-induced phase transformation between form I (triclinic unit cell) and form II (monoclinic unit cell). The phase transition between forms I and II was found at a pressure and temperature of 5.5 GPa and ≈350 K, respectively. In addition, we also studied the high-pressure polymorphic behavior of two forms of triclabendazole. At the pressure of 5.5 GPa and temperature from ≈350 K to 500 K, form II was more stable than form I. However, at temperatures lower than ≈350 K, form I was more stable than form II. We also studied the effects of pressures on volumes and Raman spectra. To the best of our knowledge, no such research has been conducted to determine the presence of phase transformation between two forms of triclabendazole. This is a case study that can be applied to various polymorphic crystals to study their structures, stabilities, spectra, and phase transformations. This research can assist scientists, chemists, and pharmacologists in selecting the desired polymorph and better drug design.

APA, Harvard, Vancouver, ISO, and other styles

49

Girin, Oleg. "ELECTROCHEMICAL POLYMORPHIC PHASE FORMATION IN METALS." Acta Metallurgica Slovaca 27, no. 3 (September 13, 2021): 139–45. http://dx.doi.org/10.36547/ams.27.3.1011.

Full text

Abstract:

The phenomenon of electrochemical phase formation in metals and alloys via a supercooled liquid state stage was discussed. Assuming the electrodeposited metal to be a product of formation and ultrarapid solidification of supercooled metallic liquid, a possibility of metastable phase formation during electrodeposition of polymorphous metals was suggested. It was anticipated that the polymorphic transition of the metal’s metastable form to the stable one occurs by shear, as does the martensitic transformation. To enable revealing an orientation relationship between grains of the two phases, a method for X-ray texture analysis of metals was developed using a combination of direct pole figures. It was established that the phase formation during electrodeposition of polymorphous metals produces metastable modifications typical of entities that crystallized from a liquid state at extremely high rates. In regards polymorphic transitions in metal electrodeposition, certain orientation relationships were observed between grains of the stable and the metastable phase, which is typical of phase transformations proceeding at extremely high rates. The results obtained provided additional arguments in favor of the phenomenon under discussion.

APA, Harvard, Vancouver, ISO, and other styles

50

Martins, Guilherme M., Roberto L. Moreira, and Anderson Dias. "A soft chemistry approach to preparing (de)sodiated transition-metal hydroxy molybdates." CrystEngComm 22, no. 11 (2020): 1939–55. http://dx.doi.org/10.1039/c9ce01554j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!