The structural manipulation of a series of Ni4 defective dicubanes: Synthesis, X-ray Structures, Magnetic and Computational analyses

2021 ◽  
Vol 50 (15) ◽  
pp. 5318-5326
Author(s):  
Sidney S. Woodhouse ◽  
Tyson N. Dais ◽  
Emily H. Payne ◽  
Mukesh K. Singh ◽  
Euan K. Brechin ◽  
...  
Keyword(s):  
Computational Analysis ◽  
X Ray ◽  
Structural Manipulation ◽  
Computational Analyses

Structural, magnetic, and computational analysis of a series of Ni4 defective dicubanes is described.

scholarly journals Occurrence, distribution and possible functional roles of simple sequence repeats in phytoplasma genomes

2015 ◽  
Vol 65 (Pt_8) ◽  
pp. 2748-2760 ◽  
Author(s):  
Wei Wei ◽  
Robert E. Davis ◽  
Xiaobing Suo ◽  
Yan Zhao
Keyword(s):  
Simple Sequence Repeats ◽  
Computational Analysis ◽  
Allelic Diversity ◽  
Regulation Of Transcription ◽  
Phase Variable ◽  
Functional Roles ◽  
Rapid Responses ◽  
Computational Analyses ◽  
Simple Sequence ◽  
Diverse Plant

Phytoplasmas are unculturable, cell-wall-less bacteria that parasitize plants and insects. This transkingdom life cycle requires rapid responses to vastly different environments, including transitions from plant phloem sieve elements to various insect tissues and alternations among diverse plant hosts. Features that enable such flexibility in other microbes include simple sequence repeats (SSRs) — mutation-prone, phase-variable short DNA tracts that function as ‘evolutionary rheostats’ and enhance rapid adaptations. To gain insights into the occurrence, distribution and potentially functional roles of SSRs in phytoplasmas, we performed computational analysis on the genomes of five completely sequenced phytoplasma strains, ‘Candidatus Phytoplasma asteris’-related strains OYM and AYWB, ‘Candidatus Phytoplasma australiense’-related strains CBWB and SLY and ‘Candidatus Phytoplasma mali’-related strain AP-AT. The overall density of SSRs in phytoplasma genomes was higher than in representative strains of other prokaryotes. While mono- and trinucleotide SSRs were significantly overrepresented in the phytoplasma genomes, dinucleotide SSRs and other higher-order SSRs were underrepresented. The occurrence and distribution of long SSRs in the prophage islands and phytoplasma-unique genetic loci indicated that SSRs played a role in compounding the complexity of sequence mosaics in individual genomes and in increasing allelic diversity among genomes. Findings from computational analyses were further complemented by an examination of SSRs in varied additional phytoplasma strains, with a focus on potential contingency genes. Some SSRs were located in regions that could profoundly alter the regulation of transcription and translation of affected genes and/or the composition of protein products.

scholarly journals Investigations concerning plasma parameters and population inversion in laser-produced counterstreaming plasmas

1991 ◽  
Vol 9 (2) ◽  
pp. 501-515 ◽  
Author(s):  
P. Glas ◽  
M. Schnürer
Keyword(s):  
Computational Analysis ◽  
Nuclear Charge ◽  
Gain Coefficient ◽  
Spectral Lines ◽  
Interaction Zone ◽  
Electron Number ◽  
Plasma Parameters ◽  
X Ray ◽  
Spatial Intensity Distribution ◽  
Resonance Transitions

We investigated the case where two laser-produced plasmas collide nearly head on. Special attention was devoted to the fundamentals necessary to realize a coherent X-ray source. A gas-dynamic computational analysis was performed to understand the evolution of the density, the temperature, and the velocity of merging plasmas. The spatial intensity distribution of selected spectral lines reveals that the interaction of plasmas of different nuclear charge and charge state is not strictly collision dominated. Using spectral line intensity ratios, we determined electron temperatures and electron number densities, as well as the intensity inversion on the 4–1 to 3–1 resonance transitions of [He]-like Al. Inversion occurs in the vicinity of the targets if identical materials are used (Al–Al) and is possibly indicated in the interaction zone for different ones (Al–Cu), too. The inversion factors (and the gain coefficient) for the 4–3 transition of [He]-like Al at about 130 Å were estimated.

The Performance of the Cold Crucible Melting of Refractory Materials

2005 ◽  
Author(s):  
B. T. Min ◽  
J. H. Song ◽  
S. H. Chung
Keyword(s):  
Computational Model ◽  
Computational Analysis ◽  
Refractory Materials ◽  
Cold Crucible ◽  
Electro Magnetic Field ◽  
High Melting Temperature ◽  
Pure Zirconia ◽  
Electro Magnetic ◽  
Computational Analyses ◽  
Very High

To investigate the performance of a cold crucible employed for the melting of refractory material, which has a very high melting temperature of about 3000 K, a computational analysis of the coupled electro-magnetic field, heat transfer, and fluid flow is carried out. Governing differential equations, basic numerical methods, computational model, and the results of the simulation of cold crucible melting are discussed. Computational Analyses were performed for the melting of corium, which is a mixture of UO2 and ZrO2, and pure zirconia. By comparing the analysis results with the experimental data, it is shown that the proposed computational model reasonably predicts the fundamental characteristics of a cold crucible melting.

N-donor stabilized complexes of nickel(II) diphenyldithiophosphates: single-crystal X-ray, HSA and computational analysis

2020 ◽  
Vol 45 (8) ◽  
pp. 531-544
Author(s):  
Deepika Sharma ◽  
Anu Radha ◽  
Pretam Kumar ◽  
Sandeep Kumar ◽  
Amanpreet K. Jassal ◽  
...  
Keyword(s):  
Single Crystal ◽  
Computational Analysis ◽  
X Ray

1,2-Bis(2,6-diisopropylphenyl)diphosphane: a structural, spectroscopic, and computational investigation

2016 ◽  
Vol 94 (4) ◽  
pp. 392-400 ◽  
Author(s):  
Leila Mokhtabad Amrei ◽  
Peter W. Dibble ◽  
René T. Boeré
Keyword(s):  
Raman Spectrum ◽  
Nmr Spectra ◽  
Computational Analysis ◽  
Spin Systems ◽  
Solution Nmr ◽  
Computational Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Peaks ◽  
Resolution Single

The title compound Dipp(H)P–P(H)Dipp where Dipp = 2,6-diisopropylyphenyl has been prepared starting from DippPH2 via DippPHLi reacting 2:1 with BrCH2CH2Br. A high-resolution single-crystal X-ray diffraction study at 153 ± 2 K provides an accurate description of the structure in the solid state, only the fourth dihydro diorganophosphane to have been so characterized. The Raman spectrum of the solid shows an intense, broad peak for P–H stretching at 2314 cm−1 and two peaks at 460 and 450 cm−1 for P–P stretching, assignments confirmed by RHF/6-31G+(3d,2p) frequency calculations undertaken on the anti conformers. 31P, 31P{1H }, 1H{31P}, and 13C{1H } solution NMR spectra in CDCl3 are consistent with the presence of 58% meso and 42% rac diastereomers. Analysis of their AA′XX′ spin systems enabled calculation of 1JPP′ values of (–)189 and (–)205 Hz, respectively. A B3LYP/6-31G(d,p) computational analysis of the energetics of rotation about the P–P bond in both diastereomers shows that the anti and two gauche conformers are likely to be populated approximately equally in each. The resulting average ϕ angles (torsions of the phosphorus lone pairs) are 110° for meso and 103° for rac; the smaller ϕ angle fits with the larger 1JPP′ value for the rac isomer.

scholarly journals SYNTHESIS, CRYSTAL STRUCTURE, HIRSHFELD SURFACE ANALYSIS AND QUANTUM CHEMICAL CALCULATIONS OF [Cu2(C6H9N3S)2(ClO4)2] π-COMPLEX WITH 2-ALLYLAMINO-5-METHYL-1,3,4-THIADIAZOLE

2021 ◽  
Vol 26 (1(77)) ◽  
pp. 16-25
Author(s):  
Yu. I. Slyvka ◽  
E. A. Goreshnik ◽  
N. T. Pokhodylo ◽  
М. G. Mys’kiv
Keyword(s):  
Crystal Structure ◽  
Computational Analysis ◽  
Structure Characterization ◽  
Electrochemical Technique ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Π Complex ◽  
Centrosymmetric Dimers

This work is focused on the synthesis and structure characterization of the novel Cu(I) π-complex [Cu2(Thiaz1)2(ClO4)2] (1) with 2-allylamino-5-methyl-1,3,4-thiadiazole (Thiaz1) ligand. The crystals of the compound were obtained by means of the alternating-current electrochemical technique and studied using single crystal X-ray diffraction. The crystal structure of the complex 1 is constructed from the centrosymmetric dimers, in which two copper(I) ions are coordinated by two Thiaz1 molecules through thiadiazole N atoms and allylic C=C bond. Energy framework computational analysis for structure 1 has been performed.  

scholarly journals Actinide Arene-Metalates: Ion Pairing Effects on the Electronic Structure of Unsupported Uranium-Arene Sandwich Complexes

2021 ◽  
Author(s):  
Jesse Murillo ◽  
Rina Bhowmick ◽  
Katie L. M. Harriman ◽  
Alejandra Gomez-Torres ◽  
Joshua Wright ◽  
...  
Keyword(s):  
Close Contact ◽  
Ion Pairing ◽  
X Ray Diffraction ◽  
Sandwich Complexes ◽  
Metal Centers ◽  
X Ray ◽  
Absorption Energy ◽  
Dimeric Complexes ◽  
Model Complex ◽  
Computational Analyses

Chatt reaction methods were employed to synthesize the first well characterized actinide-arene sandwich complexes. Namely, addition of [UI<sub>2</sub>(THF)<sub>3</sub>(μ-OMe)]<sub>2</sub>⸱THF (<b>2⸱THF</b>) to THF solutions containing 6 equiv. of K[C<sub>14</sub>H<sub>10</sub>] generates the dimeric complexes [K(18-crown-6)(THF)<sub>2</sub>]<sub>2</sub>[U(η<sup>6</sup>-C<sub>14</sub>H<sub>10</sub>)(η<sup>4</sup>-C<sub>14</sub>H<sub>10</sub>)(μ-OMe)]<sub>2</sub>⸱4THF (<b>118C6</b>⸱4THF) and {[K(THF)<sub>3</sub>][U(η<sup>6</sup>-C<sub>14</sub>H<sub>10</sub>)(η<sup>4</sup>-C<sub>14</sub>H<sub>10</sub>)(μ-OMe)]}<sub>2</sub> (<b>1THF</b>) upon crystallization of the products in THF in the presence or absence of 18-crown-6, respectively. Both <b>118C6</b>⸱4THF and <b>1THF</b> are thermally stable in the solid-state at room temperature; however, after crystallization, they become insoluble in THF or DME solutions and instead gradually decompose upon standing. X-ray diffraction analysis reveals <b>118C6</b>⸱4THF and <b>1THF</b> to be structurally similar, possessing uranium centers sandwiched between anthracene ligands of mixed tetrahapto and hexahapto ligation modes. Yet, the two complexes are distinguished by the close contact potassium-arene ion pairing that is seen in <b>1THF</b> but absent in <b>118C6</b>⸱4THF, which is observed to have a significant effect on the electronic characteristics of the two complexes. Structural analysis, SQUID magnetometry data, XANES spectral characterization, and computational analyses are generally consistent with U(IV) formal assignments for the metal centers in both <b>118C6</b>⸱4THF and 1THF, though noticeable differences are detected between the two species. For instance, the effective magnetic moment of <b>1THF</b> (3.74 µB) is significantly lower than that of <b>118C6</b>⸱4THF (4.40 µB) at 300 K. Furthermore, the XANES data shows the U LIII-edge absorption energy for 1THF to be 0.9 eV higher than that of <b>118C6</b>⸱4THF, suggestive of more oxidized metal centers in the former. Of note, CASSCF calculations on the model complex {[U(η<sup>6</sup>-C<sub>14</sub>H<sub>10</sub>)(η<sup>4</sup>-C<sub>14</sub>H<sub>10</sub>)(μ-OMe)]<sub>2</sub>}<sup>2-</sup> (<b>1*</b>) shows highly polarized uranium-arene interactions defined by π-type bonds where the metal contributions are primarily comprised by the 6d-orbitals (7.3± 0.6%) with minor participation from the 5f-orbitals (1.5 ± 0.5%). These unique complexes provide new insights into actinide-arene bonding interactions and show the sensitivity of the electronic structures of the uranium atoms to coordination sphere effects.<br>

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