Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

scholarly journals Crystal Structures of New Ivermectin Pseudopolymorphs

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 172
Author(s):  
Kirill Shubin ◽  
Agris Bērziņš ◽  
Sergey Belyakov
Keyword(s):  
Crystal Structure ◽  
Molecular Conformation ◽  
Methyl Tert Butyl Ether ◽  
Minor Role ◽  
Scanning Calorimetry ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
Structure Space

New pseudopolymorphs of ivermectin (IVM), a potential anti-COVID-19 drug, were prepared. The crystal structure for three pseudopolymorphic crystalline forms of IVM has been determined using single-crystal X-ray crystallographic analysis. The molecular conformation of IVM in crystals has been compared with the conformation of isolated molecules modeled by DFT calculations. In a solvent with relatively small molecules (ethanol), IVM forms monoclinic crystal structure (space group I2), which contains two types of voids. When crystallized from solvents with larger molecules, like γ-valerolactone (GVL) and methyl tert-butyl ether (MTBE), IVM forms orthorhombic crystal structure (space group P212121). Calculations of the lattice energy indicate that interactions between IVM and solvents play a minor role; the main contribution to energy is made by the interactions between the molecules of IVM itself, which form a framework in the crystal structure. Interactions between IVM and molecules of solvents were evaluated using Hirshfeld surface analysis. Thermal analysis of the new pseudopolymorphs of IVM was performed by differential scanning calorimetry and thermogravimetric analysis.

scholarly journals (R)-Baclofen [(R)-4-amino-3-(4-chlorophenyl)butanoic acid]

2022 ◽  
Vol 78 (1) ◽  
Author(s):  
Feodor Belov ◽  
Alexander Villinger ◽  
Jan von Langermann
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Title Compound ◽  
Single Crystal Xrd ◽  
Butanoic Acid ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
Structure Space

This article provides the first single-crystal XRD-based structure of enantiopure (R)-baclofen (form C), C10H12ClNO2, without any co-crystallized substances. In the enantiopure title compound, the molecules arrange themselves in an orthorhombic crystal structure (space group P212121). In the crystal, strong hydrogen bonds and C—H ... Cl bonds interconnect the zwitterionic molecules.

Thermal enhancement of 2H11/2→4I15/2 up-conversion luminescence of Er3+ doped K2Yb(PO4)(MoO4) phosphors

2021 ◽  
Author(s):  
Hongqiang Cui ◽  
Yongze Cao ◽  
Lei Zhang ◽  
Yuhang Zhang ◽  
Siying Ran ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Reaction Method ◽  
X Ray ◽  
Thermal Enhancement

Er3+ with different concentrations doped K2Yb(PO4)(MoO4) phosphors were prepared by a solid-state reaction method, and the layered orthorhombic crystal structure of the samples was confirmed by X-ray diffraction (XRD). Under...

Orthorhombic crystal structure of the A-DNA octamer d(GTACGTAC). Comparison with the tetragonal structure

1993 ◽  
Vol 213 (2) ◽  
pp. 673-682 ◽  
Author(s):  
Beatrice LANGLOIS d'ESTAINTOT ◽  
Alain DAUTANT ◽  
Christian COURSEILLE ◽  
Gilles PRECIGOUX
Keyword(s):  
Crystal Structure ◽  
Tetragonal Structure ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure

Influence of Deposition Time on the Properties of Highly-Oriented SnS Thin Films Prepared Using the Thermal Evaporation Method

2012 ◽  
Vol 602-604 ◽  
pp. 1409-1412 ◽  
Author(s):  
Patrick. A. Nwofe ◽  
K. T. Ramakrishna Reddy ◽  
Robert W. Miles
Keyword(s):  
Crystal Structure ◽  
Single Phase ◽  
Deposition Time ◽  
Thermal Evaporation ◽  
Atomic Ratio ◽  
Energy Band Gap ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Thermal Evaporation Method ◽  
Sns Thin Films

The influence of deposition time on the properties of SnS films grown using the thermal evaporation was reported. The deposition time was varied between 0.7 – 3 min, keeping other deposition variables constant. The layers showed single phase with orthorhombic crystal structure, exhibiting a strong (040) reflection. With an increase of deposition time, the Sn/S atomic ratio and grain size and the number of crystallites in the layers increased while the dislocation density and bulk resistivity decreased. The increase of crystallinity of the layers was confirmed by the change of strain from tensile to compressive with increasing deposition time. The transmittance of the films were > 70% for deposition time ≤ 1min and decreased drastically otherwise. The energy band gap varied in the range 1.80 - 1.30 eV with the lower values obtained at longer deposition times.

Electron density, disorder and polymorphism: high-resolution diffraction studies of the highly polymorphic neuralgic drug carbamazepine

2016 ◽  
Vol 72 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Ioana Sovago ◽  
Matthias J. Gutmann ◽  
Hans Martin Senn ◽  
Lynne H. Thomas ◽  
Chick C. Wilson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Diffraction Data ◽  
Structural Formula ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Monoclinic Crystal Structure

Analysis of neutron and high-resolution X-ray diffraction data on form (III) of carbamazepine at 100 K using the atoms in molecules (AIM) topological approach afforded excellent agreement between the experimental results and theoretical densities from the optimized gas-phase structure and from multipole modelling of static theoretical structure factors. The charge density analysis provides experimental confirmation of the partially localized π-bonding suggested by the conventional structural formula, but the evidence for any significant C—N π bonding is not strong. Hirshfeld atom refinement (HAR) gives H atom positional and anisotropic displacement parameters that agree very well with the neutron parameters. X-ray and neutron diffraction data on the dihydrate of carbemazepine strongly indicate a disordered orthorhombic crystal structure in the space groupCmca, rather than a monoclinic crystal structure in space groupP21/c. This disorder in the dihydrate structure has implications for both experimental and theoretical studies of polymorphism.

Structural, Morphological and Textural Features of EDTA-Citrate-Synthesized BaPrO3 Perovskite-Type Oxide

2018 ◽  
Vol 912 ◽  
pp. 50-54
Author(s):  
A.G. dos Santos ◽  
M.F. Lobato ◽  
A.B. Vital ◽  
Francisco Klebson Gomes dos Santos ◽  
Carlson P. de Souza
Keyword(s):  
Crystal Structure ◽  
Synthesis Method ◽  
Textural Properties ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Total Replacement ◽  
Perovskite Type Oxide ◽  
Interest In Research ◽  
Perovskite Type ◽  
Complexation Process

BaCeO3 has attracted great interest in research worldwide, whether doped with other elements on the site A and / or B of perovskite ABO3 or not, thus enabling its use in different applications. However, the properties exhibited by perovskite depend on partial or total replacement at the site, as well as the applied synthesis method. In this work we studied crystal structure, crystallographic parameters, morphology and textural properties of BaPrO3 perovskite synthesized by EDTA-Citrate complexation process. The adopted methodology makes it possible to obtain powders with orthorhombic crystal structure ( a=6.07 Å; b=6.3 Å e c=8.7 Å) and crystallite size of approximately 100 nm. That perovskite has dense and irregular agglomerates with surface area and pore volume of about 2.37 m2 g-1 and 0.7x10-8m3g-1, respectively. Finally, the methodology has demonstrated effectiveness in achieving crystalline phase with similar characteristics and properties obtained by different methods.

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