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Journal articles on the topic 'Structured derivates'

Author: Grafiati
Published: 28 June 2021
Last updated: 11 February 2022

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1

Grygiel, Marcin. "The Cognitive Motivation Behind the Semantics of Hungarian Co-Verbial Constructions with Össze and Szét." Studies in Logic, Grammar and Rhetoric 61, no. 1 (March 1, 2020): 31–47. http://dx.doi.org/10.2478/slgr-2020-0002.

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AbstractThe use of an elaborate system of co-verbial constructions is the hallmark of the Hungarian language and one of the biggest challenges a translator or a learner of this language has to face. Co-verbial constructions consist of verbs, or their derivates, accompanied by a limited number of prefixes or particles that modify their meanings. They not only perform numerous syntactic and lexical functions, which is important in terms of language production, but also are able to change the meaning of the verb completely. The aim of this study is to trace the cognitive motivation behind the use of Hungarian co-verbial constructions with össze/szét and to show that the meanings developed by these constructions can be organized with reference to prototypical scenes structured in the form of a radial category.
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2

Wünsch, L. "Checklist for the Structural Description of the Deep Phenotype in Disorders of Sexual Development." International Journal of Endocrinology 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/816365.

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This paper addresses the question, how the variations of the deep phenotype in disorders of sex development (DSD) are appropriately described. This is a relevant question, because extensive phenotypic variability occurs in gonads and sex ducts. With the advance of video endoscopy and laparoscopy, fresh insight in gonadal and sex duct anatomy is emerging. So far, an attempt to standardize the diagnostic approach and, in particular, how to document these findings has not been published. We propose a standardized examination schedule for these procedures. It consists of 5 pictures of relevant anatomic features. For laparoscopy, it includes two pictures each of gonads and sex ducts on either side and an image of the retrovesical space. For endoscopy, the examination of the ureteric orifices, the posterior urethra, and the urogenital sinus derivates is recommended. Adherence of a standardized schedule and image storing enhances patient autonomy, because they can carry their examination for a second opinion without need for repeated examination. Physicians and scientists create a structured image library that facilitates the comparison of clinical outcomes, research on genotype phenotype associations and may lead to better classifications.
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3

Freiherr von Richthofen, Carl-Georg, Bastian Feldscher, Kai-Alexander Lippert, Anja Stammler, Hartmut Bögge, and Thorsten Glaser. "Electronic and Molecular Structures of Heteroradialenes: A Combined Synthetic, Computational, Spectroscopic, and Structural Study Identifying IR Spectroscopy as a Simple but Powerful Experimental Probe." Zeitschrift für Naturforschung B 68, no. 1 (January 1, 2013): 64–86. http://dx.doi.org/10.5560/znb.2013-2241.

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The vicinity of a hydrogen bond donor (O-H) and a hydrogen bond acceptor (C=O or C=N- R) in salicylaldehydes and ortho-Schiff bases results in significant structural variations compared to the monosubstituted derivatives that are reflected in the electronic structure and thus in the spectroscopic properties. This interplay between intramolecular hydrogen bonding and multicenter p- electron delocalization is the origin of the concept of resonance-assisted hydrogen bonding (RAHB). Herein, the complexity is extended from one hydrogen bond donor-acceptor pair in salicylaldehyde and ortho-Schiff bases to three hydrogen bond donor-acceptor pairs in 2,4,6-tricarbonyl- and 2,4,6- triimine-substituted phloroglucinols (1,3,5-trihydroxybenzene), respectively. To evaluate the changes in the molecular and electronic structures, we have performed a comprehensive computational, spectroscopic, and structural study starting from monosubstituted benzene derivatives as references over ortho-disubstituted derivates to the sixfold-substituted derivatives. Whereas in salicylaldehydes, ortho- Schiff bases, and 2,4,6-tricarbonyl-phloroglucinols the phenolic O-protonated tautomers represent the energy minima, the N-protonated tautomers represent the energy minima in 2,4,6-triiminephloroglucinols. The analysis provides a keto-enamine resonance structure with six exocyclic double bonds to be dominant for these species reminiscent of [6]radialenes, which were termed heteroradialenes. These heteroradialenes are non-aromatic alicycles. However, the predominance of this resonance structure does not represent a sudden change going from the 2,4,6-tricarbonyl- to the 2,4,6-triimine-phloroglucinols, but a gradual increase of analogous resonance structure contributions is observed even in salicylaldehyde and ortho-Schiff bases demonstrating some hetero-orthoquinodimethane character. These changes are, besides in the molecular structures, well reflected in the IR spectra, which can therefore be used as a simple tool to probe the electronic structures in these systems. Interruption of the delocalized p system supporting the intramolecular hydrogen bond, i. e. going from 2,4,6-triimine- to 2,4,6-triamine-substituted phloroglucinols, reestablishes an O-protonated aromatic phloroglucinol system.
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4

Awad, Mohamed K., Saida A. El-Enien, and Mohammed H. Rizk. "Quantitative Structure-Trypanocidal Activity Relationship Analysis of Phenothiazine Derivatives." Indian Journal of Applied Research 3, no. 9 (October 1, 2011): 65–68. http://dx.doi.org/10.15373/2249555x/sept2013/20.

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5

Groth, Moritz, Kate Ponto, and Michael Shulman. "The additivity of traces in monoidal derivators." Journal of K-theory 14, no. 3 (July 14, 2014): 422–94. http://dx.doi.org/10.1017/is014005011jkt262.

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AbstractMotivated by traces of matrices and Euler characteristics of topological spaces, we expect abstract traces in a symmetric monoidal category to be “additive”. When the category is “stable” in some sense, additivity along cofiber sequences is a question about the interaction of stability and the monoidal structure.May proved such an additivity theorem when the stable structure is a triangulation, based on new axioms for monoidal triangulated categories. in this paper we use stable derivators instead, which are a different model for “stable homotopy theories”. We define and study monoidal structures on derivators, providing a context to describe the interplay between stability and monoidal structure using only ordinary category theory and universal properties. We can then perform May's proof of the additivity of traces in a closed monoidal stable derivator without needing extra axioms, as all the needed compatibility is automatic.
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6

Makovicky, E. "Crystal Structures of Complex Lanthanide Sulfides With Built-in Non-Commensurability." Australian Journal of Chemistry 45, no. 9 (1992): 1451. http://dx.doi.org/10.1071/ch9921451.

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Non-commensurability on the boundaries of adjacent structural layers (rods, blocks) represents an important structure-building principle for several structural families of complex lanthanide sulfides. In the layer-misfit sulfides 'ABS3', pseudotetragonal layers with lanthanide ions alternate with octahedral layers or trigonal prismatic layers. Among more complex, fragment-recombination structures based on similar layer strips, (A) a family of derivatives of the structure of Yb3S4, (B) structures that represent anti-(out-of-)phase modulated non-commensurate layer sequences, and (c) lanthanide sulfosalts (with bismuth and antimony) are described in some detail. Layer-match modes, their relationships to the ratios of cation radii, and relations to simpler archetypal structures are analysed.
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7

Zapata-Galván, V., L. M. Torres-Martínez, and P. Quintana. "Síntesis y caracterización de nuevas soluciones sólidas de fluoruros con estructura tipo fluorita y derivadas." Boletín de la Sociedad Española de Cerámica y Vidrio 40, no. 4 (August 30, 2001): 285–88. http://dx.doi.org/10.3989/cyv.2001.v40.i4.738.

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8

Sibiryakov, Boris, Lourenildo W. B. Leite, and Wildney W. S. Vieira. "MODEL OF THE STRUCTURED CONTINUUM, AND THE RELATION BETWEEN SPECIFIC SURFACE AREA, POROSITY AND PERMEABILITY." Revista Brasileira de Geofísica 31, no. 4 (December 1, 2013): 559. http://dx.doi.org/10.22564/rbgf.v31i4.337.

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ABSTRACT. Contrary to the Cauchy and Poisson classical seismic theory of the continuum, the new theory for structured (also called porous, fractured, or blocked) media must contain several degrees of freedom. This fact is evident because elementary blocks (grains) may transfer the motion by contact interaction, by rotation, and by group of particles. Therefore, the energy content is not only contained within the first spatial derivatives (strains), but the potential energy content is within the second (curvatures) and other higher order spatial derivatives. Thus, the equation of motion of porous media should contain higher order spatial derivatives, andmay even contain infinite order spatial derivatives.Keywords: seismic structured media, porous media, fractured media. RESUMO. Contrariamente aos problemas clássicos da teoria sísmica do contínuo de Cauchy e Poisson, a nova teoria para meios estruturados (também denominados de porosos, fraturados e blocados) deve conter vários graus de liberdade. Este fato é evidente porque blocos elementares (grãos) podem transferir movimento por interação de contato, por rotação, e por grupo de partículas. Desta forma, o conteúdo de energia não está apenas contido nas primeiras derivadas espaciais (deformações), como também o conteúdo de energia potencial está presente na segunda (curvaturas), e em derivadas espaciais de maior ordem. Sendo assim, a equação de movimento para meios porosos deveria conter derivadas espaciais de ordem mais altas, e até mesmo uma ordem infinita de derivadas espaciais.Palavras-chave: meios sísmicos estruturados, meios porosos, meios fraturados.
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9

Minasyan, Alla. "Pragmatic Aspects of Derivatives Functioning in Fiction." Armenian Folia Anglistika 8, no. 1-2 (10) (October 15, 2012): 85–90. http://dx.doi.org/10.46991/afa/2012.8.1-2.085.

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The characteristics of the formation of derivatives, the compound nature of their structure provide ample opportunities for the realization of its purposes. Various transformations can take place inside derivates – dissolution of constituents and re-arrangement, fusions, use of a morpheme as an independent word, violation of the standards of the combinability of morphemes, repetition of the morphemes in derivatives, etc. These transformations take place in linguistic units that create word-forming stylistic devices beyond their traditional area of application.
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10

Ibrayev, M. K., S. B. Akhmetova, A. T. Takibayeva, M. B. Issabayeva, A. O. Nurkenov, and О. T. Seilkhanov. "Synthesis, structure and antimicrobial activity of substituted chalcones and their derivatives." Bulletin of the Karaganda University. "Chemistry" series 95, no. 3 (September 30, 2019): 28–36. http://dx.doi.org/10.31489/2019ch3/28-36.

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11

Knitter, Gerd, Ulrich Behrens, Enno Lork, and Rüdiger Mews. "Perfluorbenzyl-Stickstoff-Derivate / Perfluorobenzyl Nitrogen Derivatives." Zeitschrift für Naturforschung B 49, no. 2 (February 1, 1994): 233–37. http://dx.doi.org/10.1515/znb-1994-0213.

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In the HgF2-assisted addition of Cl2 and Br2 to C6F5CN the compounds C6F5CF=NX (3, 5: X = Cl, Br) and C6F5CF2NX2 (2, 4: X = Cl, Br) are formed. Photochemical decomposition of the dibromoamine (4) gives the diazene C6F5CF2- N=N - CF2C6F5 (6) in 31% yield. The structure of 6 has been determined by X-ray diffraction.
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12

Karasiński, Artur. "Albańskie odczasownikowe derywaty przymiotnikowe." Slavia Meridionalis 10 (August 31, 2015): 125–34. http://dx.doi.org/10.11649/sm.2010.010.

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Albanian adjective derivatives derived from verbsThe aim of this article is the analysis of the Albanian adjective derivatives which are derived from verbs. The main assumption made by the author is the existence of structural isomorphism (parallelism in language elements system in which structuring of one level parallels or is made to parallel that of another) between the structure of the derivative and the structure of the sentence. The proposed model of the analysis is directed from content to form. All examined adjective derivatives derived from verbs are being analyzed with their noun context which displays their semantic structure. Nominal phrases containing adjective derivatives are interpreted as the representation of predicate–argument structures. The kind of relation between defined noun and derivational base of the adjective is a criterion of the division of Albanian adjective derivatives derived from verbs. These main types of relations are:relation in which the base of an adjective represents basic predicate;relation in which the base of an adjective represents additional predicate.Classes which are the results of the main division are the subject to detailed description.
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13

Prakash, Rini, Jean-François Halet, and Sundargopal Ghosh. "Polyhedral [M2B5] Metallaborane Clusters and Derivatives: An Overview of Their Structural Features and Chemical Bonding." Molecules 25, no. 14 (July 12, 2020): 3179. http://dx.doi.org/10.3390/molecules25143179.

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A large number of metallaborane clusters and their derivatives with various structural arrangements are known. Among them, M2B5 clusters and derivatives constitute a significant class. Transition metals present in these species span from group 4 to group 7. Their structure can vary from oblatonido, oblatoarachno, to arachno type open structures. Many of these clusters appear to be hypoelectronic and are often considered as ‘rule breakers’ with respect to the classical Wade–Mingos electron counting rules. This is due to their unique highly oblate (flattened) deltahedral structures featuring a cross-cluster M−M interaction. Many theoretical calculations were performed to elucidate their electronic structure and chemical bonding properties. In this review, the synthesis, structure, and electronic aspects of the transition metal M2B5 clusters known in the literature are discussed. The chosen examples illustrate how, in synergy with experiments, computational results can provide additional valuable information to better understand the electronic properties and electronic requirements which govern their architecture and thermodynamic stability.
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14

Zubyk, Halyna, Marta Plonska-Brzezinska, Olena Shyshchak, Olena Astakhova, and Michael Bratychak. "Study of Phenol-Formaldehyde Oligomers Derivatives Structure by IR- and NMR-Spectroscopy." Chemistry & Chemical Technology 9, no. 4 (December 15, 2015): 435–43. http://dx.doi.org/10.23939/chcht09.04.435.

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15

Akune, Yoko, Risa Hirosawa, Atsushi Koseki, and Shinya Matsumoto. "Role of halogen substituents in a series of polymorphic 2,5-diamino-3,6-dicyanopyrazine derivatives with highly flexible groups." Zeitschrift für Kristallographie - Crystalline Materials 232, no. 5 (May 1, 2017): 395–405. http://dx.doi.org/10.1515/zkri-2016-2007.

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AbstractThe crystal structures of the ortho-X-benzyl derivatives, where X=F, Cl, Br, I, and Me, of 2,5-bis(N,N-dibenzylamino)-3,6-dicyanopyrazine dyes (C34H24N6X4) were analysed to evaluate the effect of a systematic series of structures on the occurrence of polymorphism. Detailed crystal structure analysis indicated that the thermally stable forms of the polymorphic derivatives (Cl and Br derivatives) were close-packed, whereas those of the non-polymorphic derivatives (F and I derivatives) were stabilised by an intermolecular interaction involving the ortho-substituents. In the thermally metastable forms of the polymorphic derivative, halogen-halogen and halogen-nitrogen interactions contributed to the stabilisation of these crystals in the same way as the thermally stable form of the non-polymorphic derivatives. This indicated that the ease of polymorph occurrence would require an appropriate balance between the crystal energy of the close-packed structure and that of the crystal structure generated mainly by the electrostatic interactions involving the halogens in these halogenated pyrazine derivatives. In addition, the similar tendency of the occurrence of polymorphs in these halogenated pyrazine derivatives was found in 19 sets of halogenated compounds having known crystal structures of F, Cl, Br and I derivatives including at least one polymorphic derivative in the crystal structure database.
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16

Masuno, Hiroyuki, Daisuke Morizono, Teikichi Ikura, Nobutoshi Ito, Hector DeLuca, Hirokazu Tamamura, and Masato Shimizu. "2P032 Crystal structures of vitamin D receptor in complex with lithocholic acid derivatives(29. Protein structure and dynamics (II),Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)." Seibutsu Butsuri 46, supplement2 (2006): S303. http://dx.doi.org/10.2142/biophys.46.s303_4.

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17

Mysik, S. V. "Kinetic and Activation Characteristics of Structure Rearrangement Processes in Ethoxylated Isononylphenol Derivates." Radio Engineering, no. 1 (March 5, 2020): 17–30. http://dx.doi.org/10.36027/rdeng.0120.0000160.

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The paper presents the calculation results of the kinetic and activation characteristics of fast and ultrafast structure rearrangement processes in liquid hydroxyethylated derivates of isononylphenol (ОНФn). Parameters were calculated using the relaxation theory of acoustic spectroscopy of liquids based on the analysis of the acoustic spectra of speed and sound absorption of the hydroxyethylated derivates of isononylphenol. The paper shows that two simple regions of acoustic dispersion can describe the acoustic spectra in the frequency range from 12 MHz to 2 GHz and the temperature range from 253 K to 323 K. The dispersion region data in the hydroxyethylated derivates of isononylphenol correspond to the interconnected reactions of OH ... O bonding and breaking in chain associates and spatially branched network structures. It is noted that the change in the spatial structure of liquid hydroxyethylated derivates of isononylphenol can be considered as a set of the large number of independent (for non-collective processes) and interconnected (for collective processes) local rearrangements of the liquid structure as a result of the thermal motion of molecules. The proposed molecular mechanism of acoustic relaxation and the kinetic model of fast and ultrafast structure rearrangement processes of the hydroxyethylated derivates of isononylphenol made it possible to explain the main experimental results and to calculate the kinetic and activation characteristics of the structure rearrangement processes of the hydroxyethylated derivates of isononylphenol. This model and the kinetic and activation parameters of the hydroxyethylated derivates of isononylphenol can find application in development of various technologies for using nonionic surfactants.
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18

Ji, Yu Bin, Yan Dong, Ning Chen, Dong Xue Song, and Jia Zheng. "Structure-Activity Relationship of Two Typical Amaryllidaceae Isocarbostyril Alkaloids and their Derivatives." Applied Mechanics and Materials 411-414 (September 2013): 3158–61. http://dx.doi.org/10.4028/www.scientific.net/amm.411-414.3158.

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This paper reviews the structure-activity relationship of two typical Amaryllidaceae isocarbostyril alkaloids, narciclasine, pancratistatin and their derivatives. Varieties structures have important impacts on biological activity of Amaryllidaceae isocarbostyril alkaloids, for example, the nuclear structure of isocarbostyril, the stereochemistry of the B/C ring junction, the C7-hydroxy of ring A, hydroxies of ring C and so on. This study is conducive to find other active groups, conduct structural modifications and provide the rational basis for designing drugs molecular.
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19

Rodríguez-Arce, Esteban, Patricio Cancino, Manuel Arias-Calderón, Paul Silva-Matus, and Marianela Saldías. "Oxoisoaporphines and Aporphines: Versatile Molecules with Anticancer Effects." Molecules 25, no. 1 (December 27, 2019): 108. http://dx.doi.org/10.3390/molecules25010108.

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Cancer is a disease that involves impaired genome stability with a high mortality index globally. Since its discovery, many have searched for effective treatment, assessing different molecules for their anticancer activity. One of the most studied sources for anticancer therapy is natural compounds and their derivates, like alkaloids, which are organic molecules containing nitrogen atoms in their structure. Among them, oxoisoaporphine and sampangine compounds are receiving increased attention due to their potential anticancer effects. Boldine has also been tested as an anticancer molecule. Boldine is the primary alkaloid extract from boldo, an endemic tree in Chile. These compounds and their derivatives have unique structural properties that potentially have an anticancer mechanism. Different studies showed that this molecule can target cancer cells through several mechanisms, including reactive oxygen species generation, DNA binding, and telomerase enzyme inhibition. In this review, we summarize the state-of-art research related to oxoisoaporphine, sampangine, and boldine, with emphasis on their structural characteristics and the relationship between structure, activity, methods of extraction or synthesis, and anticancer mechanism. With an effective cancer therapy still lacking, these three compounds are good candidates for new anticancer research.
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20

Wnuk, Małgorzata, Michał Marszałł, Anna Zapęcka, Alicja Nowaczyk, Jerzy Krysiński, Jerzy Romaszko, Piotr Kawczak, Tomasz Bączek, and Adam Buciński. "Prediction of antimicrobial activity of imidazole derivatives by artificial neural networks." Open Medicine 8, no. 1 (February 1, 2013): 1–15. http://dx.doi.org/10.2478/s11536-012-0052-6.

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AbstractThe main goal of our study is the analysis of data obtained from molecular modeling for a series of imidazole derivatives that possess strong antifungal activity. The research was designed to use artificial neural network (ANN) analysis to determine quantitative relationships between the structural parameters and anti-Streptococcus pyogenes activity of a series of imidazole derivatives. ANN in association with quantitative structure-activity relationships (QSAR) represents a promising tool in the search for drug candidates among the practically unlimited number of possible derivatives. In this work, a series of 286 imidazole derivatives presented as cationic three-dimensional structures was used. The activity was expressed as a logarithm of the reciprocal of the minimal inhibitory concentrations, log 1/MIC. Multilayer perceptron ANN was used for predictions of antimicrobial potency of new imidazole derivatives on the basis of their structural descriptors. The obtained correlation coefficient equaled 0.9461 for the learning set, 0.9060 for the validation set and 0.8824 for the testing set of imidazole derivatives. Hence, satisfactory and practically useful predictions of anti-Streptococcus pyogenes activity for a series of imidazole derivatives was obtained, supporting the future successful interpretation of QSAR analysis for those compounds.
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21

Hreniukh, V. P., N. S. Finiuk, and Ya R. Shalai. "Effects of thiazole derivatives on intracellular structure and functions in murine lymphoma cells." Ukrainian Biochemical Journal 92, no. 2 (April 17, 2020): 121–30. http://dx.doi.org/10.15407/ubj92.02.121.

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22

Santos, Clementina M. M., and Artur M. S. Silva. "The Antioxidant Activity of Prenylflavonoids." Molecules 25, no. 3 (February 6, 2020): 696. http://dx.doi.org/10.3390/molecules25030696.

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Prenylated flavonoids combine the flavonoid moiety and the lipophilic prenyl side-chain. A great number of derivatives belonging to the class of chalcones, flavones, flavanones, isoflavones and other complex structures possessing different prenylation patterns have been studied in the past two decades for their potential as antioxidant agents. In this review, current knowledge on the natural occurrence and structural characteristics of both natural and synthetic derivatives was compiled. An exhaustive survey on the methods used to evaluate the antioxidant potential of these prenylflavonoids and the main results obtained were also presented and discussed. Whenever possible, structure-activity relationships were explored.
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23

Wang, Huan, Yuxiao Liu, Zhuoyue Chen, Lingyu Sun, and Yuanjin Zhao. "Anisotropic structural color particles from colloidal phase separation." Science Advances 6, no. 2 (January 2020): eaay1438. http://dx.doi.org/10.1126/sciadv.aay1438.

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Structural color materials have been studied for decades because of their fascinating properties. Effects in this area are the trend to develop functional structural color materials with new components, structures, or morphologies for different applications. In this study, we found that the coassembled graphene oxide (GO) and colloid nanoparticles in droplets could form component phase separations, and thus, previously unknown anisotropic structural color particles (SCPs) with hemispherical colloidal crystal cluster and oblate GO component could be achieved. The anisotropic SCPs, as well as their inverse opal hydrogel derivatives, were endowed with brilliant structural colors and controllable capabilities of fixation, location, orientation, and even responsiveness due to their specific structure, morphology, and components. We have also demonstrated that the anisotropic hydrogel SCPs with these features were ideal candidates for dynamic cell monitoring and sensing. These properties indicate that the anisotropic SCPs and their derivatives have huge potential values in biomedical areas.
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24

Jiao, Ti Feng, Xu Hui Li, Jing Xin Zhou, Yuan Yuan Xing, and Jing Ren. "Research on Some Novel Functional Azobenzene Derivatives with Alkyl Chains and Different Substituted Groups." Key Engineering Materials 474-476 (April 2011): 537–42. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.537.

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Two functional azobenzene derivatives with alkyl chains and different substituted groups have been synthesized and their photoisomerization have also been investigated. It has been found that depending on the alkyl chain and different substituted groups, the formed azobenzene derivatives showed different properties, indicating distinct regulation of molecular skeletons. UV and IR data confirmed commonly the characteristic absorption of alkyl chain and aromatic segments in molecular structures. Thermal analysis demonstrated that the structural influence of both compounds in different temperature ranges. The difference of thermal stability is mainly attributed to the formation of Schiff base group and different substituent groups in molecular structure. The photoisomerization of these compounds both in solution and in cast film can undergo trans-to-cis isomerization by UV light irradiation, depending on different substituted groups. The present results have demonstrated that the special properties of azobenzene derivatives can be effectively turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in functional material field.
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Fernandes, Carla, Maria Carraro, João Ribeiro, Joana Araújo, Maria Tiritan, and Madalena Pinto. "Synthetic Chiral Derivatives of Xanthones: Biological Activities and Enantioselectivity Studies." Molecules 24, no. 4 (February 22, 2019): 791. http://dx.doi.org/10.3390/molecules24040791.

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Many naturally occurring xanthones are chiral and present a wide range of biological and pharmacological activities. Some of them have been exhaustively studied and subsequently, obtained by synthesis. In order to obtain libraries of compounds for structure activity relationship (SAR) studies as well as to improve the biological activity, new bioactive analogues and derivatives inspired in natural prototypes were synthetized. Bioactive natural xanthones compromise a large structural multiplicity of compounds, including a diversity of chiral derivatives. Thus, recently an exponential interest in synthetic chiral derivatives of xanthones (CDXs) has been witnessed. The synthetic methodologies can afford structures that otherwise could not be reached within the natural products for biological activity and SAR studies. Another reason that justifies this trend is that both enantiomers can be obtained by using appropriate synthetic pathways, allowing the possibility to perform enantioselectivity studies. In this work, a literature review of synthetic CDXs is presented. The structures, the approaches used for their synthesis and the biological activities are described, emphasizing the enantioselectivity studies.
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Zhang, Jiwen, Lihui Cui, Longbo Li, Zhan Hu, Qianliang Zhang, Zhaonong Hu, and Wenjun Wu. "Synthesis and Insecticidal Activities of Novel Nitrogenous Derivatives of Celangulin-V." Natural Product Communications 9, no. 6 (June 2014): 1934578X1400900. http://dx.doi.org/10.1177/1934578x1400900603.

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In order to develop new biorational pesticides and clarify the potential structural factors needed for the biological activity of celangulin-V analogues, thirty novel nitrogenous derivatives were designed and synthesized. The single crystal structure of celangulin-V is reported for the first time and provides a more accurate structure than that previously reported. The structures of all the new derivatives were confirmed by either NMR or ESI-MSn analysis. Insecticidal activities of these compounds were tested against the third-instar larvae of Mythimna separata. One derivative (1–6) showed higher insecticidal activity than celangulin-V, with a KD50 of 231.2 μg.g–1, while two compounds (2–13 and 2–14) exhibited lower insecticidal activities; the others revealed no activity at a concentration of 20 mg mL−1. The results support the view that celangulin-V has the potential to be a lead structure of semi-synthetic green insecticides.
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27

Megnassan, Eugene, Issouf Fofana, Brice Dali, Frederica Mansilla Koblavi, Vladimir Frecer, and Stanislav Miertus. "Structure-Based Design of Tetrahydroisoquinoline-Based Hydroxamic Acid Derivatives Inhibiting Human Histone Deacetylase 8." SDRP Journal of Computational Chemistry & Molecular Modeling 5, no. 1 (2021): 504–38. http://dx.doi.org/10.25177/jccmm.5.1.ra.10708.

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We have designed new human histone deacetylase 8 (HDAC8) inhibitors using structure-based molecular design. 3D models of HDAC8–inhibitor complexes were prepared by in situ modification of the crystal structure of HDAC8 co-crystallized with the hydroxamic acid suberoylanilide (SAHA) and a training set (TS) of tetrahydroisoquinoline-based hydroxamic acid derivatives (DAHTs) with known inhibitory potencies. A QSAR model was elaborated for the TS yielding a linear correlation between the computed Gibbs free energies (GFE) of HDAC8–DAHTs complexation (∆∆Gcom) and observed half-maximal enzyme inhibitory concentrations (IC50exp). From this QSAR model a 3D-QSAR pharmacophore (PH4) was generated. Structural information derived from the 3D model and breakdown of computed HDAC8–DAHTs interaction energies up to individual active site residue contributions helped us to design new more potent HDAC8 inhibitors. We obtained a reasonable agreement ∆∆Gcom and values: (pIC50exp = – 0.0376 × ∆∆Gcom + 7.4605, R2 = 0.89). Similar agreement was established for the PH4 model (pIC50exp = 0.8769 × + 0.7854, R2 = 0.87). A comparative analysis of the contributions of active site residues guided the choice of fragments used in designing a virtual combinatorial library (VCL) of DAHT analogs. The VCL of more than 17 thousand DAHTs was screened by the PH4 and furnished 229 new DAHTs. The best-designed analog displayed predicted inhibitory potency up to 110 times higher than that of DAHT1 (IC50exp = 0.047 µM). Predicted pharmacokinetic profiles of the new analogs were compared to current per oral anticancer compounds. This computational approach, which combines molecular modelling, pharmacophore generation, analysis of HDAC8–DAHTs interaction energies and virtual screening of a combinatorial library of DAHTs resulted in a set of proposed new HDAC8 inhibitors. It can thus direct medicinal chemists in their search for new anticancer agents.
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28

McEwan, Iain J., and Ann M. Nardulli. "Nuclear Hormone Receptor Architecture - Form and Dynamics: The 2009 FASEB Summer Conference on Dynamic Structure of the Nuclear Hormone Receptors." Nuclear Receptor Signaling 7, no. 1 (January 2009): nrs.07011. http://dx.doi.org/10.1621/nrs.07011.

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Nuclear hormone receptors (NHRs) represent a large and diverse family of ligand-activated transcription factors involved in regulating development, metabolic homeostasis, salt balance and reproductive health. The ligands for these receptors are typically small hydrophobic molecules such as steroid hormones, thyroid hormone, vitamin D3 and fatty acid derivatives. The first NHR structural information appeared ∼20 years ago with the solution and crystal structures of the DNA binding domains and was followed by the structure of the agonist and antagonist bound ligand binding domains of different NHR members. Interestingly, in addition to these defined structural features, it has become clear that NHRs also possess significant structural plasticity. Thus, the dynamic structure of the NHRs was the topic of a recent stimulating and informative FASEB Summer Research Conference held in Vermont.
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29

Fatima, Bushra, Sunil Singh Chouhan, Nikita Acharya, and S. P. Sanyal. "Structural, Electronic, Elastic and Mechanical Properties of ScNi, ScPd and ScPt: A FP-LAPW Study." Advanced Materials Research 1047 (October 2014): 27–34. http://dx.doi.org/10.4028/www.scientific.net/amr.1047.27.

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Systematic first principles calculations have been carried out to study the structural, electronic, elastic and mechanical properties of ScNi, ScPd and ScPt using FP-LAPW method within GGA. The ground state properties such as lattice constant, bulk modulus and first order pressure derivates of bulk modulus, were evaluated. The electronic and bonding patterns of these compounds have been analysed quantitatively from band structure and Fermi surfaces. It is clear from band structures that these compounds are metallic in nature. Ductility for these compounds is analysed by using Pugh’s criteria, Cauchy pressure (C12–C44) and Frantsevich rule. Amongst all these Sc compounds, ScNi is found to be most ductile due to the presence of strong metallic bonding.
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30

Pechinskii, Stanislav V., Eduard T. Oganesyan, and Anna G. Kuregyan. "The factor patent of invention when drafting the text of the pharmacopoeic article." Farmacevticheskoe delo i tehnologija lekarstv (Pharmacy and Pharmaceutical Technology), no. 1 (January 1, 2021): 16–21. http://dx.doi.org/10.33920/med-13-2101-01.

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Molecular docking is a convenient and cost-effective tool for targeted screening of biologically active structures. This method makes it possible to reveal the relationship between structure and activity, as well as to search for new active compounds. Due to the fact that the antiviral activity of flavonoids and their derivatives has been shown experimentally and clinically, the study of their antiviral activity against SARS-CoV-2 is a promising study. In an in silico experiment, the possibility of binding 20 flavonoid ligands and the main protease SARS-CoV-2 was studied. The structural features of flavone and flavanone derivatives have been determined, which determine their ability to block the main protease of the SARS-CoV-2 virus. Structures of eight new candidates that bind the main protease SARS-CoV-2, which have the prospect of synthesis and further pharmacological research, have been proposed.
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31

Pechinskii, Stanislav V., Eduard T. Oganesyan, and Anna G. Kuregyan. "Search for active candidates in a range of flavonoids regarding SARS-CoV-2 by the method of molecular docking." Farmacevticheskoe delo i tehnologija lekarstv (Pharmacy and Pharmaceutical Technology), no. 1 (January 1, 2021): 22–35. http://dx.doi.org/10.33920/med-13-2101-02.

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Molecular docking is a convenient and cost-effective tool for targeted screening of biologically active structures. This method makes it possible to reveal the relationship between structure and activity, as well as to search for new active compounds. Due to the fact that the antiviral activity of flavonoids and their derivatives has been shown experimentally and clinically, the study of their antiviral activity against SARS-CoV-2 is a promising study. In an in silico experiment, the possibility of binding 20 flavonoid ligands and the main protease SARS-CoV-2 was studied. The structural features of flavone and flavanone derivatives have been determined, which determine their ability to block the main protease of the SARS-CoV-2 virus. Structures of eight new candidates that bind the main protease SARS-CoV-2, which have the prospect of synthesis and further pharmacological research, have been proposed.
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32

Talanov, M. V., V. B. Shirokov, and V. M. Talanov. "Anion order in perovskites: a group-theoretical analysis." Acta Crystallographica Section A Foundations and Advances 72, no. 2 (January 29, 2016): 222–35. http://dx.doi.org/10.1107/s2053273315022147.

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Anion ordering in the structure of cubic perovskite has been investigated by the group-theoretical method. The possibility of the existence of 261 ordered low-symmetry structures, each with a unique space-group symmetry, is established. These results include five binary and 14 ternary anion superstructures. The 261 idealized anion-ordered perovskite structures are considered as aristotypes, giving rise to different derivatives. The structures of these derivatives are formed by tilting ofBO6octahedra, distortions caused by the cooperative Jahn–Teller effect and other physical effects. Some derivatives of aristotypes exist as real substances, and some as virtual ones. A classification of aristotypes of anion superstructures in perovskite is proposed: theAXclass (the simultaneous ordering ofAcations and anions in cubic perovskite structure), theBXclass (the simultaneous ordering ofBcations and anions) and theXclass (the ordering of anions only in cubic perovskite structure). In most perovskites anion ordering is accompanied by cation ordering. Therefore, the main classes of anion order in perovskites are theAXandBXclasses. The calculated structures of some anion superstructures are reported. Comparison of predictions and experimentally investigated anion superstructures shows coherency of theoretical and experimental results.
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33

Todosijević, Jovana, Alexander Scherbakov, Yulia Volkova, and Vladimir Jurišić. "Investigation of the effect of steroidal imidazoheterocycles hormone derivatives on JEG-3 trophoblast cells of choriocarcinoma." Kragujevac Journal of Science, no. 43 (2021): 99–107. http://dx.doi.org/10.5937/kgjsci2143099t.

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This study aimed to examine the biological activities of unique steroid hormone derivatives-steroidal imidazoheterocycles. The activity synthesized steroidal compounds were tested for the viability of JEG-3 trophoblast cells of choriocarcinoma. The results of the MTT cytotoxicity test showed that most of the examined steroidal imidazoheterocycles act proliferatively on the JEG-3 cell line, except (E, F, and J). Antiproliferative activity of these derivates is probably influenced by different substituents at position 17-C atom in the chemical structure of the hormone and by different substituents on the oxygen atom of acetamide group in the hormone molecule. In order to better confirm the antiproliferative activity of these derivatives, it is necessary to performed complex research on a large panel of cancer cell lines and by different assay.
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34

Ivashkiv, Ostap, Olena Astakhova, Olena Shyshchak, Marta Plonska-Brzezinska, and Michael Bratychak. "Structure and Application of ED-20 Epoxy Resin Hydroxy-Containing Derivatives in Bitumen-Polymeric Blends." Chemistry & Chemical Technology 9, no. 1 (March 15, 2015): 69–76. http://dx.doi.org/10.23939/chcht09.01.069.

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35

Gao, Hua Bin, and Yong Sheng Zhang. "Determination of Torsional Mode and Analysis of Torsional Resistance." Applied Mechanics and Materials 204-208 (October 2012): 1242–46. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1242.

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At present, structural designers have many different views on determination of torsional mode. This paper adopts the structural mode factor and the mass participation factor method to determine structure torsional mode. Use the shear correction to simplify the calculation of structure torsion, derivate the relevant formulas of torsional effect, it has guide significance for manual calculation of structural torsion; Analysis of structural torsion resistant measures finally.
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36

Bock, Hans, Sven Holl, and Volker Krenzel. "Wechselwirkungen in Molekülkristallen, 166 [1, 2]. Polyiod-Moleküle I2C=CI2, (IC)4S, (IC)4NH, (IC)4N-CH3 und HCI3: Strukturbestimmung nach Kristallzüchtung oder durch Dichtefunktionaltheorie-Berechnung / Interaction in Molecular Crystals, 166 [1, 2], Polyiodo Molecules I2C=CI2, (IC)4S, (IC)4 NH, (IC)4N-CH and HCI3: Structure Determination Following Crystallization or by Density Functional Theory Calculation." Zeitschrift für Naturforschung B 56, no. 1 (January 1, 2001): 13–24. http://dx.doi.org/10.1515/znb-2001-0104.

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Abstract The structures of tri-and tetraiodo-substituted carbon compounds are determined either expe­rimentally by X-Ray Structure Analysis or, because crystallization of tetraiodothiophene could not be achieved, approximated by Density Functional Theory optimization of structural data from a donor/acceptor complex. The structures show noteworthy details such as a second po­lymorph of tetraiodoethene crystallized by sublimation or herringbone crystal packing patterns of tetraiodopyrrole derivatives. All molecular geometries are discussed and compared based on relativistic density functional theory calculations with 6 -31G* basis sets including iodine pseudopotentials. They reproduce even finer structural details due to van der Waals repulsion of the bulky iodo substituents. Natural Bond Orbital (NBO) charge distributions suggest positive partial charges at all iodine centers with the strongest polarization Cδ㊀ → Iδ㊉ in HCI3, which contains well over 97% iodine.
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37

Zhou, Jing Xin, Ti Feng Jiao, Feng Yan Wang, and Xu Hui Li. "Photoisomerization of some Functional Azobenzene-Containing Metal Complexes with Different Substituted Groups." Advanced Materials Research 581-582 (October 2012): 453–56. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.453.

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In this work, two functional azobenzene-containing metal complexes with different substituted groups have been synthesized and their photoisomerization have also been investigated. It has been found that depending on different substituted groups, the formed azobenzene derivatives showed different properties, indicating distinct regulation of molecular skeletons. Spectral data confirmed commonly the characteristic absorption of substituted groups and aromatic segments in molecular structures. Thermal analysis demonstrated that the structural influence of both compounds in different temperature ranges. The difference of thermal stability is mainly attributed to the formation of Schiff base group and different substituent groups in molecular structure. The photoisomerization of these compounds both in solution and in cast film can undergo trans-to-cis isomerization by UV light irradiation, depending on different substituted groups. The present results have demonstrated that the special properties of azobenzene derivatives can be effectively turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in sensor and functional material field.
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38

Makovicky, Emil. "Modular Crystal Chemistry of Thallium Sulfosalts." Minerals 8, no. 11 (October 24, 2018): 478. http://dx.doi.org/10.3390/min8110478.

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Complex sulfides of thallium with As, Sb, or Bi and with other cations (‘thallium sulfosalts’) are a large group of crystal structures with extreme variability. Incorporation of the large Tl+ cation in them is solved in several different ways: housing of Tl in columns of capped trigonal coordination prisms, which form separate walls in the structure (in different combinations with Pb and/or Sb), regular alternation of large Tl with small cations (As), presence of structural arrays of Tl coordination polyhedra paralleled by arrays of As coordination pyramids with a frequency ratio 1:2, omission derivatives with cavities for Tl accommodation and formation of layer structures with thallium concentrated into separate (inter)layers of different types. The first principle leads to a large family of sartorite homologues and rare lillianite homologues, as well as to the chabournéite group. The second one to the hutchinsonite family, omission derivatives form the routhierite and galkhaite groups, and the 1:2 periodicity ratio principle results in several outstanding structures from different groups. Layer structures consist of two-component and three-component layer combinations. Close cation-cation interactions are present but rare.
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39

Rivera, Jose L., Pedro Navarro-Santos, Roberto Guerra-Gonzalez, and Enrique Lima. "Interaction of Refractory Dibenzothiophenes and Polymerizable Structures." International Journal of Polymer Science 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/103945.

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We carried out first principles calculations to show that polymerizable structures containing hydroxyl (alcoholic chain) and amino groups are suitable to form stable complexes with dibenzothiophene (DBT) and its alkyl derivates. These sulfur pollutants are very difficult to eliminate through traditional catalytic processes. Spontaneous and exothermic interactions at 0 K primarily occur through the formation of stable complexes of organosulfur molecules with monomeric structures by hydrogen bonds. The bonds are formed between the sulfur atom and the hydrogen of the hydroxyl group; additional hydrogen bonds are formed between the hydrogen atoms of the organosulfur molecule and the nitrogen atoms of the monomers. We vary the number of methylene groups in the alcoholic chain containing the hydroxyl group of the monomer and find that the monomeric structure with four methylene groups has the best selectivity towards the interaction with the methyl derivates with reference to the interaction with DBT. Even this study does not consider solvent and competitive adsorption effects; our results show that monomeric structures containing amino and hydroxyl groups can be used to develop adsorbents to eliminate organosulfur pollutants from oil and its derivates.
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40

Mykhalichko, V. M., L. O. Fedyna, A. O. Fedorchuk, and M. F. Fedyna. "Crystal structure of new ternary disilicide of platinum and erbium." Voprosy Khimii i Khimicheskoi Tekhnologii, no. 4 (July 2021): 84–88. http://dx.doi.org/10.32434/0321-4095-2021-137-4-84-88.

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Crystal structure of the ternary compound ErPtSi2 (diffractometer HZG-4a, CuK-radiation, structure type YIrGe2, Pearson symbol oI32, space group Immm, a=4.19395(6) Å, b=8.41465(13) Å, c=15.85404(19) Å, RB=0.0639, Rp=0.0424, and 2=1.11) was studied by X-ray powder diffraction method. Intermetallide ErPtSi2 is the first representative of YIrGe2 structure type in R–Pt–Si systems. Crystal structures of ternary compounds in the system Er–Pt–Si were analyzed and the structural relationships between them were established according to the systematics of the nearest coordination environment around the less electronegative Er atoms. Compounds, found in the system, were divided into two main types based on the nearest coordination environment, namely on the derivatives of hexagonal and pentagonal prisms with different amounts of additional atoms. These polyhedra exist both alone and in the combination with each other and with cubooctahedra in the structures of the different ternary silicides of erbium. Such a relatively small coordination environment of rare-earth metal atoms can be explained by the structural peculiarities of the ErPt3 binary compound. The coordination polyhedra of the smallest atoms are trigonal prisms with different amounts of additional atoms or cubooctahedra.
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41

Xia, Aibing, John P. Selegue, Alberto Carrillo, Brian O. Patrick, Sean Parkin, and Carolyn Pratt Brock. "Two fluoradene derivatives: pseudosymmetry, eccentric ellipsoids and a phase transition." Acta Crystallographica Section B Structural Science 57, no. 4 (July 24, 2001): 507–16. http://dx.doi.org/10.1107/s0108768101008631.

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Structures of two derivatives of the curved fluoradene ring system (C19H12) have been determined. Both have phases that are highly pseudosymmetric. At room temperature crystals of 7b-triisopropylsilylfluoradene (C28H32Si) have a P\bar 1 cell that contains two independent molecules (Z′ = 2) and that is almost centered. Crystals of 7b-(2,4-dinitrophenyl)fluoradene (C25H14N2O4) have both a P21/c cell with Z′ = 1 and a P21/c cell with Z′ = 2. The molecular volumes in these two P21/c structures differ by 0.7%, but the structures are otherwise virtually the same; the two independent molecules in the larger cell are related by a pseudotranslation. Some of the atomic ellipsoids in the P21/c, Z′ = 1 structure are very large and eccentric, and there are some hints in the diffraction pattern of an incipient phase transition, but the Z′ = 1 and Z′ = 2 phases are clearly different. The P21/c, Z′ = 2 crystal at 295 K probably contains some volume fraction of the Z′ = 1 phase; when the temperature is lowered to 273 K this fraction is decreased markedly. The pronounced pseudosymmetry in the P\bar 1 and P21/c structures that have Z′ = 2 has been investigated by analysing the atomic coordinates, by performing refinements in the smaller pseudocells and by making separate Wilson plots for the classes of reflections which are systematically strong and systematically weak. All three approaches are informative, but they reveal different information. Least-squares fits of coordinates of corresponding atoms measure the similarity of the molecular conformations. The Wilson plots allow a quantitative comparison of the intensities of the strong and weak reflections and thus an assessment of the deviations of the true structure from the smaller pseudocell structure. Comparison of the atomic displacements obtained in the full and pseudocell refinements shows where the structural distortions are largest and provides an indication of their directions."
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42

Surace, Cecilia. "Damage Assessment of Structures Using only Post-Damage Vibration Measurements." Key Engineering Materials 569-570 (July 2013): 11–22. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.11.

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Damage to many structural systems (including bridges, offshore platforms, airplanes and aerospace systems) can occur during normal service due to fatigue loading, a corrosive environment, collisions with extraneous objects, etc. For such structures, in order to guarantee safety, periodic inspections and maintenance are essential: Since undetected damage may result in catastrophic structural failure, the realisation of an accurate and trustworthy damage detection technique is fundamental.Vibration-based inspection offers the potential for detecting faults by monitoring the dynamic response of a structure, exploiting the fundamental principle that structural damage affects the stiffness distribution and hence the presence of the fault will change the dynamic properties of the structure under investigation.Many vibration-based inspection techniques have been developed over recent years which require knowledge of the baseline modal responses of the structure in the original undamaged state.However, for the vast majority of existing structures in operation, such data are simply not available. This keynote presentation reviews past and present research studies in which the author has been involved that aim to detect the presence of structural damage and identify its approximate location, using only post-damage vibration measurements. The techniques presented analyse either the mode shapes, operating deflection shapes or principal orthogonal modes and their corresponding derivatives. These features have been found to be good indicators of damage due to the spatial information that can be provided with respect to location of damage. The methodologies proposed are applied to isotropic/orthotropic uni/bi-dimensional structures and corresponding numerical and experimental results are presented.
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43

Yaniv, Gili, David Fuks, and Louisa Meshi. "Explanation of structural differences and similarities between the AT2Al10 phases (where A=actinide, lanthanide or rare earth element and T=transition metal)." Zeitschrift für Kristallographie - Crystalline Materials 234, no. 9 (September 25, 2019): 595–603. http://dx.doi.org/10.1515/zkri-2019-0007.

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Abstract In the current work we have studied the crystallographic relationship between the AT2Al10 phases (where A = actinide, lanthanide and rare earth element and T = transition metal). It is known that with this stoichiometry two structure types exist: tetragonal CaCr2Al10 and orthorhombic YbFe2Al10. It was found that both CaCr2Al10 and YbFe2Al10 types are structural derivatives of the ThMn12 type structure (which has more general formula of ATxAl12−x, with x > 2). CaCr2Al10 structure has a group-subgroup relationship with the ThMn12 structure, while the relationship of the YbFe2Al10 to the ThMn12 was proved applying the strong reflection approach, suggested initially for approximants of quasi-crystals. Proposed here relationship between the studied structures explains the small difference in total energies, calculated using Density Functional Theory. Understanding the connection between these phases allows regarding AT2Al10 composition as somewhat extension of the ATxAl12−x compositional range. Due to the unique magnetic properties of the ATxAl12−x phases, tunable as a function of crystallographic structure, study of structural stability and crystallographic relationships of related phases are of outmost importance.
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44

Huang, Xiaobo, and Hui Xu. "Advances on the Bioactivities, Total Synthesis, Structural Modification, and Structure-Activity Relationships of Cytisine Derivatives." Mini-Reviews in Medicinal Chemistry 20, no. 5 (April 25, 2020): 369–95. http://dx.doi.org/10.2174/1389557519666191104121821.

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Cytisine is a quinolizidine alkaloid isolated from various Leguminosae plants. Cytisine and its derivatives exhibit a broad range of biological properties, such as smoking cessation aid, antidepressant, neuroprotective, nootropic, anticancer, antiviral, antiparasitic, antidiabetic, insecticidal, and nematicidal activities. In this review, the progress of cytisine and its derivatives in regard to bioactivities, total synthesis, structural modifications focusing on their N-12 position and lactam ring is reported. Additionally, the structure-activity relationships of cytisine and its derivatives are also discussed.
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45

Wu, Xinming. "Directional structure-tensor-based coherence to detect seismic faults and channels." GEOPHYSICS 82, no. 2 (March 1, 2017): A13—A17. http://dx.doi.org/10.1190/geo2016-0473.1.

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Seismic coherence is widely used in seismic interpretation and reservoir characterization to highlight (with low values) faults and stratigraphic features from a seismic image. A coherence image can be computed from the eigenvalues of conventional structure tenors, which are outer products of gradients of a seismic image. I have developed a simple but effective method to improve such a coherence image by using directional structure tensors, which are different from the conventional structure tensors in only two aspects. First, instead of using image gradients with vertical and horizontal derivatives, I use directional derivatives, computed in directions perpendicular and parallel to seismic structures (reflectors), to construct directional structure tensors. With these directional derivatives, lateral seismic discontinuities, especially those subtle stratigraphic features aligned within dipping structures, can be better captured in the structure tensors. Second, instead of applying Gaussian smoothing to each element of the constructed structure tensors, I apply approximately fault- and stratigraphy-oriented smoothing to enhance the lateral discontinuities corresponding to faults and stratigraphic features in the structure tensors. Real 3D examples show that the new coherence images computed from such structure tensors display much cleaner and more continuous faults and stratigraphic features compared with those computed from conventional structure tensors and covariance matrices.
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46

Mocanu, Anca Mihaela, Constantin Luca, and Alina Costina Luca. "Synthesis, Characterization and Thermal Degradation of Some New 3,5-dimethyl Pyrazole Derivatives." Revista de Chimie 68, no. 2 (March 15, 2017): 317–22. http://dx.doi.org/10.37358/rc.17.2.5444.

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The purpose of this research is to synthetize, characterize and thermal degradation of new heterolytic derivates with potential biological properties. The derivates synthesis was done by obtaining new molecules with pyralozone structure which combine two pharmacophore entities: the amidosulfonyl-R1,R2 phenoxyacetil with the 3,5-dimethyl pyrazole which can have potential biological properties. The synthesis stages of the new products are presented as well as the elemental analysis data and IR, 1H-NMR spectral measurements made for elucidating the chemical structures and thermostability study which makes evident the temperature range proper for their use and storage. The obtained results were indicative of a good correlation of the structure with the thermal stability as estimated by means of the initial degradation temperatures as well as with the degradation mechanism by means of the TG-FTIR analysis.
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47

Li, Xian Chao, Hong Zong Si, Hua Gao, Hong Lin Zhai, and Yun Bo Duan. "Quantitative Structure Activity Relationship of New 7-Oxycoumarin Derivatives as Potent and Selective Monoamine Oxidase a Inhibitors." Advanced Materials Research 798-799 (September 2013): 1109–12. http://dx.doi.org/10.4028/www.scientific.net/amr.798-799.1109.

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New series of 4-methyl and 3,4-dimethyl-7-oxycoumarin derivatives showed in vitro high anity and selectivity toward MAO-A isoenzyme. To build the quantitative structure-activity relationships (QSAR) between the molecular structures and the inhibitory of 32 compounds, and to further discuss the structural factors that influenced the selectivity of compounds. The topological, constitutional, geometrical, electrostatic and quantum-chemical descriptors of 32 compounds were calculated by CODESSA, and these descriptors were preselected with the heuristic method (HM). As a result, the four descriptor linear model was developed to describe the relationship between the molecular structures and the selectivity of MAO-A inhibitors. Based on the model, we can also designed new compounds with higher activities finally.
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48

Tan, Xue-Jie, Shuai Liu, Xiao-Ming Hei, Feng-Cun Yang, Peng-Bing He, Feng Guo, and Dian-Xiang Xing. "Structural and theoretical study of four novel norcantharidine derivatives: two new cases of conditional isomorphism." Acta Crystallographica Section C Structural Chemistry 76, no. 1 (January 1, 2020): 75–86. http://dx.doi.org/10.1107/s2053229619016164.

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Structural and theoretical studies of four novel 5,6-dehydronorcantharidine (DNCA)/norcantharidine (NCA) derivatives, namely (3aR,4S,7R,7aS)-2-phenyl-3a,4,7,7a-tetrahydro-4,7-epoxy-1H-isoindole-1,3(2H)-dione, C14H11NO3 (DNCA-A), (3aR,4S,7R,7aS)-2-(4-nitrophenyl)-3a,4,7,7a-tetrahydro-4,7-epoxy-1H-isoindole-1,3(2H)-dione, C14H10N2O5 (DNCA-NA), (3aR,4S,7R,7aS)-2-(4-nitrophenyl)-3a,4,5,6,7,7a-hexahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione, C14H12N2O5 (NCA-NA), and (3aR,4S,7R,7aS)-2-(2-hydroxyethyl)-3a,4,5,6,7,7a-hexahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione, C10H13NO4 (NCA-AE), are reported. The supramolecular interactions and single-crystal structural characteristics of these molecules, together with the crystal structures of four other similar molecules, i.e. NCA-A (the 4-phenyl derivative of NCA-NA), DNCA-AE (the 5,6-unsaturated derivative of NCA-AE), DNCA and NCA, were analysed. Surprisingly, DNCA-A and NCA-A, as well as DNCA–NA and NCA-NA, proved to be isomorphic, while DNCA-AE and NCA-AE, as well as DNCA and NCA, have very different crystal structures. These are very rare isostructural examples between unsaturated and saturated oxanorbornene/oxanorbornane derivatives. To further explore how noncovalent interactions (NCIs) affect the degree of isomorphism in this particular series of rigid molecules where there is a fairly limited conformational degree of freedom, all four pairs of crystal structures were analyzed in parallel. The differentiation in NCIs which entails the packing mode of similar molecules is supported by energy calculations based on real or exchanged crystal structures. Our results show that minor structural differences may result in very different supramolecular interactions, and so lead to altered packing modes in the crystalline solids. Even if isostructurality sometimes occurs, the possibility of various molecular packing types cannot be ruled out. On the other hand, isomorphism may just be the result of kinetic possibilities instead of relative thermodynamic stabilities. Though crystal structure prediction is formidable, the comparison method based on existing crystal structures and quantum calculations can be used to predict the probability of isomorphism. This understanding will help us to design new norbornene derivatives with specified structures.
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49

Schmidt, Martin U., Erich F. Paulus, Nadine Rademacher, and Graeme M. Day. "Experimental and predicted crystal structures of Pigment Red 168 and other dihalogenated anthanthrones." Acta Crystallographica Section B Structural Science 66, no. 5 (September 11, 2010): 515–26. http://dx.doi.org/10.1107/s0108768110028247.

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The crystal structures of 4,10-dibromo-anthanthrone (Pigment Red 168; 4,10-dibromo-dibenzo[def,mno]chrysene-6,12-dione), 4,10-dichloro- and 4,10-diiodo-anthanthrone have been determined by single-crystal X-ray analyses. The dibromo and diiodo derivatives crystallize in P21/c, Z = 2, the dichloro derivative in P\bar 1, Z = 1. The molecular structures are almost identical and the unit-cell parameters show some similarities for all three compounds, but the crystal structures are neither isotypic to another nor to the unsubstituted anthanthrone, which crystallizes in P21/c, Z = 8. In order to explain why the four anthanthrone derivatives have four different crystal structures, lattice-energy minimizations were performed using anisotropic atom–atom model potentials as well as using the semi-classical density sums (SCDS-Pixel) approach. The calculations showed the crystal structures of the dichloro and the diiodo derivatives to be the most stable ones for the corresponding compound; whereas for dibromo-anthanthrone the calculations suggest that the dichloro and diiodo structure types should be more stable than the experimentally observed structure. An experimental search for new polymorphs of dibromo-anthanthrone was carried out, but the experiments were hampered by the remarkable insolubility of the compound. A metastable nanocrystalline second polymorph of the dibromo derivative does exist, but it is not isostructural to the dichloro or diiodo compound. In order to determine the crystal structure of this phase, crystal structure predictions were performed in various space groups, using anisotropic atom–atom potentials. For all low-energy structures, X-ray powder patterns were calculated and compared with the experimental diagram, which consisted of a few broad lines only. It turned out that the crystallinity of this phase was not sufficient to determine which of the calculated structures corresponds to the actual structure of this nanocrystalline polymorph.
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50

Fox, Daniel J. F. "Contact Schwarzian Derivatives." Nagoya Mathematical Journal 179 (2005): 163–87. http://dx.doi.org/10.1017/s0027763000025630.

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Abstract:
AbstractH. Sato introduced a Schwarzian derivative of a contactomorphism of ℝ3 and with T. Ozawa described its basic properties. In this note their construction is extended to all odd dimensions and to non-flat contact projective structures. The contact projective Schwarzian derivative of a contact projective structure is defined to be a cocycle of the contactomorphism group taking values in the space of sections of a certain vector bundle associated to the contact structure, and measuring the extent to which a contactomorphism fails to be an automorphism of the contact projective structure. For the flat model contact projective structure, this gives a contact Schwarzian derivative associating to a contactomorphism of ℝ2n−1 a tensor which vanishes if and only if the given contactomorphism is an element of the linear symplectic group acting by linear fractional transformation.
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