scholarly journals Crystallographic Insights into Uranyl Sulfate Minerals Formation: Synthesis and Crystal Structures of Three Novel Cesium Uranyl Sulfates

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 660 ◽  
Author(s):  
Olga S. Tyumentseva ◽  
Ilya V. Kornyakov ◽  
Sergey N. Britvin ◽  
Andrey A. Zolotarev ◽  
Vladislav V. Gurzhiy
Keyword(s):  
Elevated Temperatures ◽  
Topological Analysis ◽  
Structural Complexity ◽  
Hydrothermal Conditions ◽  
Crystal Chemical Analysis ◽  
Complexity Measures ◽  
Uranyl Sulfate ◽  
Sulfate Minerals ◽  
Bonding System ◽  
The Common

An alteration of the uranyl oxide hydroxy-hydrate mineral schoepite [(UO2)8O2(OH)12](H2O)12 at mild hydrothermal conditions was studied. As the result, four different crystalline phases Cs[(UO2)(SO4)(OH)](H2O)0.25 (1), Cs3[(UO2)4(SO4)2O3(OH)](H2O)3 (2), Cs6[(UO2)2(SO4)5](H2O)3 (3), and Cs2[(UO2)(SO4)2] (4) were obtained, including three novel compounds. The obtained Cs uranyl sulfate compounds 1, 3, and 4 were analyzed using single-crystal XRD, EDX, as well as topological analysis and information-based structural complexity measures. The crystal structure of 3 was based on the 1D complex, the topology of which was unprecedented for the structural chemistry of inorganic oxysalts. Crystal chemical analysis performed herein suggested that the majority of the uranyl sulfates minerals were grown from heated solutions, and the temperature range could be assumed from the manner of interpolyhedral linkage. The presence of edge-sharing uranyl bipyramids most likely pointed to the temperatures of higher than 100 °C. The linkage of sulfate tetrahedra with uranyl polyhedra through the common edges involved elevated temperatures but of lower values (~70–100 °C). Complexity parameters of the synthetic compounds were generally lower than that of uranyl sulfate minerals, whose structures were based on the complexes with the same or genetically similar topologies. The topological complexity of the uranyl sulfate structural units contributed the major portion to the overall complexity of the synthesized compounds, while the complexity of the respective minerals was largely governed by the interstitial structure and H-bonding system.

scholarly journals Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Ilya V. Kornyakov ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Complexity ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Complexity Measures ◽  
X Ray ◽  
The Family ◽  
Similarities And Differences ◽  
Related Compounds

Single crystals of two novel shchurovskyite-related compounds, K2Cu[Cu3O]2(PO4)4 (1) and K2.35Cu0.825[Cu3O]2(PO4)4 (2), were synthesized by crystallization from gaseous phase and structurally characterized using single-crystal X-ray diffraction analysis. The crystal structures of both compounds are based upon similar Cu-based layers, formed by rods of the [O2Cu6] dimers of oxocentered (OCu4) tetrahedra. The topologies of the layers show both similarities and differences from the shchurovskyite-type layers. The layers are connected in different fashions via additional Cu atoms located in the interlayer, in contrast to shchurovskyite, where the layers are linked by Ca2+ cations. The structures of the shchurovskyite family are characterized using information-based structural complexity measures, which demonstrate that the crystal structure of 1 is the simplest one, whereas that of 2 is the most complex in the family.

scholarly journals Synthesis and crystal structure of a new polymorph of potassium europium(III) bis(sulfate) monohydrate, KEu(SO4)2·H2O

2018 ◽  
Vol 74 (2) ◽  
pp. 242-245 ◽  
Author(s):  
Avijit Kumar Paul
Keyword(s):  
Crystal Structure ◽  
Topological Analysis ◽  
Structural Connectivity ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Monoclinic Space Group ◽  
Hydrothermal Conditions ◽  
Metal Sulfate ◽  
Synthesis And Crystal Structure ◽  
Trigonal Prismatic

The mixed-metal sulfate, KEu(SO4)2·H2O, has been obtained as a new polymorph using hydrothermal conditions. The crystal structure is isotypic with NaCe(SO4)2·H2O and shows a three-dimensional connectivity of the tetrahedral sulfate units with EuIII and KI ions. Tricapped trigonal–prismatic EuO9 units and square-antiprismatic KO8 units link the SO4 tetrahedra, building the three-dimensional structure. Topological analysis reveals the existence of two nodes with 6- and 10-connected nets. The compound was previously reported [Kazmierczak & Höppe (2010). J. Solid State Chem. 183, 2087–2094] in the monoclinic space group P21/c with a similar structural connectivity and coordination environments to the present compound.

The role of task sequencing in fluency, accuracy, and complexity: Investigating the SSARC model of pedagogic task sequencing

2018 ◽  
Vol 24 (5) ◽  
pp. 642-665 ◽  
Author(s):  
Aleksandra Malicka
Keyword(s):  
Cognitive Complexity ◽  
Speech Rate ◽  
Structural Complexity ◽  
Simple Complex ◽  
Complexity Measures ◽  
Complex Sequence ◽  
Task Sequencing ◽  
Sequence Versus ◽  
Individual Task

This study set out to test the theoretical premise of the SSARC model of pedagogic task sequencing, which postulates that tasks should be sequenced for learners from cognitively simple to complex. This experiment compared the performance of three tasks differing in cognitive complexity in a simple–complex sequence versus in the absence of any other tasks. There were two groups in the study: (1) participants who performed the three tasks in the simple–complex sequence, and (2) participants who performed either the simple, the complex, or the most complex task. The participants’ speech was analysed using fluency, accuracy, and complexity measures. The results indicate that simple–complex sequencing led to a higher speech rate, greater dysfluency, enhanced accuracy, and greater structural complexity, as compared to individual task performance. The results are discussed in terms of the SSARC model and pedagogical implications of the findings are presented.

scholarly journals The Spider Anatomy Ontology (SPD)—A Versatile Tool to Link Anatomy with Cross-Disciplinary Data

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 202 ◽  
Author(s):  
Martín J. Ramírez ◽  
Peter Michalik
Keyword(s):  
Structural Complexity ◽  
Morphological Diversity ◽  
Biomedical Ontologies ◽  
Anatomy Ontology ◽  
Common Reference ◽  
Versatile Tool ◽  
Open Biomedical Ontologies ◽  
Reference Ontology ◽  
The Common ◽  
And Behavior

Spiders are a diverse group with a high eco-morphological diversity, which complicates anatomical descriptions especially with regard to its terminology. New terms are constantly proposed, and definitions and limits of anatomical concepts are regularly updated. Therefore, it is often challenging to find the correct terms, even for trained scientists, especially when the terminology has obstacles such as synonyms, disputed definitions, ambiguities, or homonyms. Here, we present the Spider Anatomy Ontology (SPD), which we developed combining the functionality of a glossary (a controlled defined vocabulary) with a network of formalized relations between terms that can be used to compute inferences. The SPD follows the guidelines of the Open Biomedical Ontologies and is available through the NCBO BioPortal (ver. 1.1). It constitutes of 757 valid terms and definitions, is rooted with the Common Anatomy Reference Ontology (CARO), and has cross references to other ontologies, especially of arthropods. The SPD offers a wealth of anatomical knowledge that can be used as a resource for any scientific study as, for example, to link images to phylogenetic datasets, compute structural complexity over phylogenies, and produce ancestral ontologies. By using a common reference in a standardized way, the SPD will help bridge diverse disciplines, such as genomics, taxonomy, systematics, evolution, ecology, and behavior.

Synthesis of clay-sized iron oxides under marine hydrothermal conditions

Clay Minerals ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 719-731 ◽  
Author(s):  
N. Taitel-Goldman ◽  
A. Singer
Keyword(s):  
Crystal Growth ◽  
Short Range ◽  
Elevated Temperatures ◽  
Complete Oxidation ◽  
Alkaline Ph ◽  
Hydrothermal Conditions ◽  
Atlantis Ii Deep ◽  
Pure Phase ◽  
Acidic Conditions ◽  
Morphology Changes

AbstractGoethite, lepidocrocite, magnetite and akaganeite were synthesized in 0.8 M, 2 M and 5 M NaCl solutions at various temperatures (25, 40, 60°C) under slightly acidic to slightly alkaline pH with or without Si additions. Elevated temperatures prevent complete oxidation of initial Fe2+ solutions and magnetite and siderite precipitate, accompanied by goethite and lepidocrocite. At higher salinity, O2 solubility is reduced and its distribution is limited, leading to coprecipitation of lepidocrocite, akaganeite and goethite.Lepidocrocite morphology changes from plates at pH 5.5 through rods at pH 7 to multi-domainic crystals at pH 8.2, due to enhanced crystal growth along the c axis. Salinity and temperature have opposite effects on lepidocrocite crystallinity.Goethite crystals are multi-domainic and twinning appears only at elevated temperatures. Increases in temperature and salinity improve goethite crystallinity as observed by IR spectra. Addition of Si up to Si/Fe = 0.1 retards crystal growth and Si-OH-stretching bands appear. At Si/Fe = 1 most of the precipitate is short range ordered.Platy and rod-shaped lepidocrocite from the Thetis and Atlantis II Deeps, were probably formed under the slightly acidic conditions of the hydrothermal brines. The Si concentration was greater in Atlantis II Deep than in Thetis Deep, leading to larger lepidocrocite and goethite crystals in the latter.Multi-domainic goethite could have precipitated throughout. Pure phase goethite might have precipitated in the less concentrated brine, whereas mixtures of goethite and lepidocrocite might have precipitated in the more concentrated brine, depending mainly on oxidation rate and oxygen mobility within the brine.

Cognitive Complexity Measures

2011 ◽  
pp. 263-279
Author(s):  
Sanjay Misra
Keyword(s):  
Software Engineering ◽  
Computer Science ◽  
Cognitive Complexity ◽  
Complexity Measures ◽  
Advantages And Disadvantages ◽  
Engineering Mathematics ◽  
Standardization Process ◽  
Core Issue ◽  
The Common ◽  
Common Problems

Cognitive informatics (CI), a multidisciplinary area of research tries to solve the common problems in the field of informatics, computer science, software engineering, mathematics, cognitive science, neurobiology, psychology, and physiology. Measurement in software engineering is also a core issue which is still striving for its standardization process. In recent years, several cognitive complexity measures based on CI have been proposed. However, each of them has their own advantages and disadvantages. This chapter presents a critical review on existing cognitive complexity measures. Furthermore, a comparative study based on some selected attributes has been presented.

scholarly journals Synchrotron Diffraction Study of the Crystal Structure of Ca(UO2)6(SO4)2O2(OH)6·12H2O, a Natural Phase Related to Uranopilite

Minerals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 569
Author(s):  
Sergey Krivovichev ◽  
Nicolas Meisser ◽  
Joel Brugger ◽  
Dmitry Chernyshov ◽  
Vladislav Gurzhiy
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Structural Complexity ◽  
Dimensional Structure ◽  
Uranyl Ions ◽  
Ambient Conditions ◽  
Synchrotron Diffraction ◽  
Uranyl Sulfate ◽  
Using Data ◽  
Oriented Parallel

The crystal structure of a novel natural uranyl sulfate, Ca(UO2)6(SO4)2O2(OH)6·12H2O (CaUS), has been determined using data collected under ambient conditions at the Swiss–Norwegian beamline BM01 of the European Synchrotron Research Facility (ESRF). The compound is monoclinic, P21/c, a = 11.931(2), b = 14.246(6), c = 20.873(4) Å, β = 102.768(15), V = 3460.1(18) Å3, and R1 = 0.172 for 3805 unique observed reflections. The crystal structure contains six symmetrically independent U6+ atoms forming (UO7) pentagonal bipyramids that share O…O edges to form hexamers oriented parallel to the (010) plane and extended along [1–20]. The hexamers are linked via (SO4) groups to form [(UO2)6(SO4)2O2(OH)6(H2O)4]2− chains running along the c-axis. The adjacent chains are arranged into sheets parallel to (010). The Ca2+ ions are coordinated by seven O atoms, and are located in between the sheets, providing their linkage into a three-dimensional structure. The crystal structure of CaUS is closely related to that of uranopilite, (UO2)6(SO4)O2(OH)6·14H2O, which is also based upon uranyl sulfate chains consisting of hexameric units formed by the polymerization of six (UO7) pentagonal bipyramids. However, in uranopilite, each (SO4) tetrahedron shares its four O atoms with (UO7) bipyramids, whereas in CaUS, each sulfate group is linked to three uranyl ions only, and has one O atom (O16) linked to the Ca2+ cation. The chains are also different in the U:S ratio, which is equal to 6:1 for uranopilite and 3:1 for CaUS. The information-based structural complexity parameters for CaUS were calculated taking into account H atoms show that the crystal structure of this phase should be described as very complex, possessing 6.304 bits/atom and 1991.995 bits/cell. The high structural complexity of CaUS can be explained by the high topological complexity of the uranyl sulfate chain based upon uranyl hydroxo/oxo hexamers and the high hydration character of the phase.

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