phase analysis
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2022 ◽  
pp. 1-6
Author(s):  
Hui Li ◽  
Meng He ◽  
Ze Zhang

Quantitative phase analysis is one of the major applications of X-ray powder diffraction. The essential principle of quantitative phase analysis is that the diffraction intensity of a component phase in a mixture is proportional to its abundance. Nevertheless, the diffraction intensities of the component phases cannot be compared with each other directly since the coherent scattering power per unit cell (or chemical formula) of each component phase is usually different. The coherent scattering power per unit cell of a crystal is well represented by the sum of the squared structure factors, which cannot be calculated directly when the crystal structure data is unavailable. Presented here is a way to approximate the coherent scattering power per unit cell based solely on the unit cell parameters and the chemical contents. This approximation is useful when the atomic coordinates for one or more of the phases in a sample are unavailable. An assessment of the accuracy of the approximation is presented. This assessment indicates that the approximation will likely be within 10% when X-ray powder diffraction data is collected over a sufficient portion of the measurable pattern.


Author(s):  
Alexander M. Sherwood ◽  
Robert B. Kargbo ◽  
Kristi W. Kaylo ◽  
Nicholas V. Cozzi ◽  
Poncho Meisenheimer ◽  
...  

Psilocybin {systematic name: 3-[2-(dimethylamino)ethyl]-1H-indol-4-yl dihydrogen phosphate} is a zwitterionic tryptamine natural product found in numerous species of fungi known for their psychoactive properties. Following its structural elucidation and chemical synthesis in 1959, purified synthetic psilocybin has been evaluated in clinical trials and has shown promise in the treatment of various mental health disorders. In a recent process-scale crystallization investigation, three crystalline forms of psilocybin were repeatedly observed: Hydrate A, Polymorph A, and Polymorph B. The crystal structure for Hydrate A was solved previously by single-crystal X-ray diffraction. This article presents new crystal structure solutions for the two anhydrates, Polymorphs A and B, based on Rietveld refinement using laboratory and synchrotron X-ray diffraction data, and density functional theory (DFT) calculations. Utilizing the three solved structures, an investigation was conducted via Rietveld method (RM) based quantitative phase analysis (QPA) to estimate the contribution of the three different forms in powder X-ray diffraction (PXRD) patterns provided by different sources of bulk psilocybin produced between 1963 and 2021. Over the last 57 years, each of these samples quantitatively reflect one or more of the hydrate and anhydrate polymorphs. In addition to quantitatively evaluating the composition of each sample, this article evaluates correlations between the crystal forms present, corresponding process methods, sample age, and storage conditions. Furthermore, revision is recommended on characterizations in recently granted patents that include descriptions of crystalline psilocybin inappropriately reported as a single-phase `isostructural variant.' Rietveld refinement demonstrated that the claimed material was composed of approximately 81% Polymorph A and 19% Polymorph B, both of which have been identified in historical samples. In this article, we show conclusively that all published data can be explained in terms of three well-defined forms of psilocybin and that no additional forms are needed to explain the diffraction patterns.


2022 ◽  
Vol 2155 (1) ◽  
pp. 012035
Author(s):  
S Dyussembekova ◽  
V Kinev ◽  
A Smirnova ◽  
P Gladyshev

Abstract This article is deals with the synthesis of hybrid organic-inorganic perovskite crystals. We present a brief review of the literature devoted to the synthesis of perovskite crystals. We have analyzed methods for the synthesis of perovskite crystals to select optimal conditions. Bulk perovskite crystals of CH3NH3PbI3 were synthesized. The resulting crystals were analyzed by X-ray phase analysis, which confirms the formation of tetragonal perovskite crystals and can be used to obtain thin films.


2021 ◽  
pp. 53-69
Author(s):  
Giselle García Hípola ◽  
Javier Antón Merino ◽  
Sergio Pérez Castaños

This research analyses three fundamental questions to determine how, when and by whom emotions are used in campaign materials (political propaganda). Focusing on the 2019 European elections we carry out a three-phase analysis. Firstly, we check the use of rational content against content that appeals to voters’ emotions. Secondly, we observe which of these emo tions are channelled towards the use of negative strategies and, therefore, identifying who is the object of this attack. And lastly, we determine which party families make the most use of humorous content since this resource is believed to be part of an appeal to voter’s feelings and, therefore, it is essential to know if there are differences between political groups. Considering this analytical strategy, the structure of the work begins with the contextualisation of the 2019 European elections to focus, later, on highlighting the importance of electoral campaigns as a given time when communicative activity intensifies. Once the importance of electoral campaigns has been defined the article analyses how campaign materials, in a general context of political propaganda, are one of the most powerful tools. In this sense, the analytical strategy of political parties’ campaign materials can be said to focus on the use of emotions. Data from the European Elections Monitoring Center (EEMC) has been used not only for theoretical contextualization, but throughout the whole paper.


Author(s):  
Maxime Beneyto ◽  
Philippe Maury ◽  
Anne Rollin ◽  
Pierre Mondoly ◽  
Franck Mandel ◽  
...  

2021 ◽  
Author(s):  
Adham Rafikov ◽  
Dildora Sadikova ◽  
Oybek Tursunkulov ◽  
Malika Zubaydullaeva

Abstract Coordination complexes of collagen with copper (II) sulfate were synthesized at different ratios of the starting materials. For the synthesis, a collagen solution was used, isolated from the skin of cattle, and then freed from electrolytes by dialysis. With an increase in the salt content, the yield of the reaction product increases. The composition and structure of the complex were determined by FT-IR spectroscopy, SEM, X-ray phase analysis, and differential scanning calorimetry. The complex is formed due to the coordination interaction of with the nitrogen and oxygen atom of collagen and water. An inadequate change in the composition of the complexes with a change in the initial ratio of the components was found. With an excess of collagen, some of it does not bind into a complex and precipitates. With an excess of salt, almost all of the collagen is bound into a complex and a rhombic single crystal is formed. The composition of the complex changes not due to a change in the coordination number , but due to an increase in the amount of these ions. An X-ray phase analysis of the starting materials and complexes has been carried out. The correspondence of the parameters of the crystal structure in the X-ray spectra of the complexes was found for a wide ratio of the starting materials. The synthesized complexes have been successfully used for dyeing textile materials.


2021 ◽  
Author(s):  
А. Ultarakova ◽  
◽  
N. Lokhova ◽  
A. Yessengaziyev ◽  
◽  
...  

The article presents the study results for alkaline leaching of fine ilmenite concentrate dusts from electric smelting. The physical and chemical properties of the dusts were studied using chemical and instrumental analysis methods. The dust composition was determined, X-ray phase analysis showed that the dust sample substance is in the X-ray amorphous state, iron is present in the trivalent state, and silicon is bound to magnesium. The dust sample study using a scanning electron microscope showed that part of the titanium is bound in a hard-to-disclose anasovite encapsulated in amorphous silicon oxide. The leaching study of electric smelting dust with sodium hydroxide solutions included the study of the effect of sodium hydroxide concentration, process duration, temperature, S: L ratio. The optimal conditions for dust leaching from electric smelting of ilmenite concentrate have been established: temperature 80-90 °C, duration 90-120 min, ratio S: L = 1: 5, the concentration of sodium hydroxide solution 110-115 g/dm3. The silicon extraction degree into the solution under these conditions was 77.7%. The behavior of accompanying components of chromium, zinc, iron, and manganese during dust leaching was also studied. X-ray phase analysis of the cake after leaching shows almost complete amorphization of the leached product, the main phase is a solid solution of Fe2O3·TiO2.


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