scholarly journals The influence of L ligands on the {RuNO}6/7 bonding situation in cis-[Ru(NO)(NO2)L1–4]q complexes: a theoretical insight

RSC Advances ◽  
2015 ◽  
Vol 5 (85) ◽  
pp. 69057-69066 ◽  
Author(s):  
K. F. Andriani ◽  
G. F. Caramori ◽  
A. Muñoz-Castro ◽  
F. G. Doro
Keyword(s):  
Coordination Environment ◽  
Before And After ◽  
In Cis ◽  
Theoretical Insight

The nature of the Ru–NO interaction before and after reduction of cis-[Ru(NO)(NO2)L1–4]q complexes is modulated by the coordination environment of the metallic center, resulting in more labile on complexes with weak π-acceptor ligands.

Effect of axial coordination environment on quantum tunnelling magnetization for dysprosium single ion magnet with theoretical insight

2022 ◽  
Author(s):  
Arpan Mondal ◽  
Sanjit Konar
Keyword(s):  
Structural Analysis ◽  
Coordination Environment ◽  
Quantum Tunnelling ◽  
Axial Coordination ◽  
Theoretical Insight

Herein, we report two mononuclear Dysprosium complexes [Dy(H4L){B(OMe)2(Ph)2}2](Cl)∙MeOH (1), and [Dy(H4L){MeOH)2(NCS)2](Cl) (2) (where H4L = 2,2′-(pyridine-2,6-diylbis(ethan-1-yl-1-ylidene))bis(N-phenylhydrazinecarboxamide) with different axial coordination environment. The structural analysis revealed that the pentadentate H4L ligand...

Chemical Structures in CIS-1, 4-Polybutadiene Vulcanizates. Model Compound Approach

1970 ◽  
Vol 43 (3) ◽  
pp. 549-571 ◽  
Author(s):  
E. C. Gregg ◽  
S. E. Katrenick
Keyword(s):  
Molecular Weight ◽  
Calibration Curve ◽  
Model Compound ◽  
Chemical Compounds ◽  
Alkyl Derivative ◽  
Chemical Structures ◽  
Sulfur Vulcanization ◽  
Before And After ◽  
Chemical Crosslinks ◽  
In Cis

Abstract We studied the vulcanization reaction of one curing recipe for cis-1,4-polybutadiene (CB). The curing recipe was zinc oxide (ZnO), diphenylguanidine (DPG), 2,2′-bis(benzothiazolyl) disulfide (MBTS), and sulfur and it produced only polysulfidic crosslinks. Devulcanization of this CB vulcanizate by phenyllithium solution permitted a comparison of the molecular weight of the CB before and after vulcanization. A small but measurable reduction of the molecular weight of the rubber occurred as a result of the vulcanization reaction. Reaction of the curing recipe in cis, cis-1,5-cyclooctadiene (COD) permitted the study of the fate of the curing chemicals in the vulcanizate because COD is an accurate chemical model for CB. This study showed that: 1. The vulcanization reaction consumes none of the DPG and none of the ZnO. 2. An insoluble coating forms on the ZnO and separates it from the vulcanization reaction during at least part of the reaction. 3. All of the MBTS reacts to form one compound: an S-alkyl derivative of 2-mercaptobenzothiazole attached to the rubber molecule at a point next to a thiacyclohexene ring. 4. All the sulfur reacts to form crosslinks and intramolecular rings. The rings are three-, five-, and six-membered thiacycloalkanes and five- and six-membered thiacycloalkenes. Some of the rings are isolated and some are next to crosslinks. 5. The three-membered rings are episulfide and they are very likely the key intermediate to the formation of the cyclic and crosslink structures. 6. The crosslinks are polysulfidic and occur singly and as clusters of two and four. The more crosslinks in a cluster, the less unsaturation in its vicinity. The four-link cluster has no unsaturation and occurs as two pairs with thiacyclopentane rings between. The sum of the single crosslinks and clusters of crosslinks in the model network agrees with the number of elastically effective chemical crosslinks found in the CB vulcanizate as measured by swelling in benzene. The elastically effective chemical crosslinks in the vulcanizate were calculated by the Flory-Rehner equation and the Moore-Watson calibration curve. This agreement proves that the theory of rubber elasticity in the form of the Flory-Rehner equation and the Moore-Watson calibration curve may be used to count the number of elastically effective chemical crosslinks in a sulfur vulcanizate. Three new chemical compounds and a new method for quantitatively titrating mercaptans are disclosed. The success of this technique recommends it for further study of sulfur vulcanization by other recipes and the study of other vulcanizate changes.

Ru–NO and Ru–NO2bonding linkage isomerism in cis-[Ru(NO)(NO)(bpy)2]2+/+complexes – a theoretical insight

2014 ◽  
Vol 43 (23) ◽  
pp. 8792-8804 ◽  
Author(s):  
Karla Furtado Andriani ◽  
Giovanni Finoto Caramori ◽  
Fábio Gorzoni Doro ◽  
Renato Luis Tame Parreira
Keyword(s):  
Ground State ◽  
Ground State Structure ◽  
Energy Profile ◽  
State Structure ◽  
Linkage Isomers ◽  
Linkage Isomerism ◽  
Calculated Energy ◽  
In Cis ◽  
Theoretical Insight

Calculated energy profile (kcal mol−1) for linkage isomers relative to the ground state structure (GS)1aprior the monoelectronic reduction.

scholarly journals Somatic structural variant formation is guided by and influences genome architecture

2021 ◽  
Author(s):  
Nikos Sidiropoulos ◽  
Balca R. Mardin ◽  
Francisco German Rodríguez-Gonzalez ◽  
Shilpa Garg ◽  
Adrian M. Stütz ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Uterine Cancer ◽  
Replication Timing ◽  
Chromatin Organization ◽  
Chromatin Architecture ◽  
Mediated Effects ◽  
Before And After ◽  
Cancer Types ◽  
In Cis ◽  
Genomic Structural Variants

The occurrence and formation of genomic structural variants (SV) is known to be influenced by the 3D chromatin architecture , but the extent and magnitude has been challenging to study. Here, we apply Hi-C to study chromatin organization before and after induction of chromothripsis in human cells. We use Hi-C to manually assemble the derivative chromosomes following the massive complex rearrangements, which allowed us to study the sources of SV formation and their consequences on gene regulation. We observe an action-reaction interplay whereby the 3D chromatin architecture directly impacts on the location and formation of SVs. In turn, the SVs reshape the chromatin organization to alter the local topologies, replication timing and gene regulation in cis. We show that genomic compartments and replication timing are important determinants for juxtaposing distant loci to form SVs across 30 different cancer types with a pronounced abundance of SVs between early replicating regions in uterine cancer. We find that SVs frequently occur at 3D loop-anchors, cause compartment switching and changes in replication timing, and that this is a major source of SV-mediated effects on nearby gene expression changes.

scholarly journals Solution structures and biophysical analysis of full-length group A PAKs reveal they are monomeric and auto-inhibited in cis

2019 ◽  
Vol 476 (7) ◽  
pp. 1037-1051 ◽  
Author(s):  
Fiona J. Sorrell ◽  
Lena Marie Kilian ◽  
Jonathan M. Elkins
Keyword(s):  
Catalytic Domain ◽  
Molecular Shape ◽  
Kinase Domain ◽  
Full Length ◽  
Activation Mechanism ◽  
Regulatory Domain ◽  
Biophysical Analysis ◽  
Before And After ◽  
Group A ◽  
In Cis

Abstract The group A p21-activated kinases (PAKs) exist in an auto-inhibited form until activated by GTPase binding and auto-phosphorylation. In the auto-inhibited form, a regulatory domain binds to the kinase domain (KD) blocking the binding of substrates, and CDC42 or Rac binding to the regulatory domain relieves this auto-inhibition allowing auto-phosphorylation on the KD activation loop. We have determined the crystal structure of the PAK3 catalytic domain and by small angle X-ray scattering, the solution-phase structures of full-length inactive PAK1 and PAK3. The structures reveal a compact but elongated molecular shape that demonstrates that, together with multiple independent biophysical measurements and in contrast with previous assumptions, group A PAKs are monomeric both before and after activation, consistent with an activation mechanism of cis-auto-inhibition and initial cis-auto-phosphorylation, followed by transient dimerisation to allow trans-auto-phosphorylation for full activation, yielding a monomeric active PAK protein.

Deformation Replication

1970 ◽  
Vol 28 ◽  
pp. 280-281
Author(s):  
J. Temple Black
Keyword(s):  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Rake Face ◽  
Orthogonal Machining ◽  
Aluminum Chips ◽  
Before And After ◽  
Materials Used ◽  
Glass Knife ◽  
Very High

Tool materials used in ultramicrotomy are glass, developed by Latta and Hartmann (1) and diamond, introduced by Fernandez-Moran (2). While diamonds produce more good sections per knife edge than glass, they are expensive; require careful mounting and handling; and are time consuming to clean before and after usage, purchase from vendors (3-6 months waiting time), and regrind. Glass offers an easily accessible, inexpensive material ($0.04 per knife) with very high compressive strength (3) that can be employed in microtomy of metals (4) as well as biological materials. When the orthogonal machining process is being studied, glass offers additional advantages. Sections of metal or plastic can be dried down on the rake face, coated with Au-Pd, and examined directly in the SEM with no additional handling (5). Figure 1 shows aluminum chips microtomed with a 75° glass knife at a cutting speed of 1 mm/sec with a depth of cut of 1000 Å lying on the rake face of the knife.

The Clinical, Roentgenological and Morphological Effects of an Acute Exposure of Phosgene on the Lungs of Dogs

1971 ◽  
Vol 29 ◽  
pp. 236-237
Author(s):  
R. F. Bils ◽  
W. F. Diller ◽  
F. Huth
Keyword(s):  
Latent Period ◽  
Chemical Industry ◽  
Toxic Substance ◽  
Lung Edema ◽  
X Rays ◽  
Beagle Dogs ◽  
Male And Female ◽  
Morphological Alterations ◽  
Before And After ◽  
Electron Microscopes

Phosgene still plays an important role as a toxic substance in the chemical industry. Thiess (1968) recently reported observations on numerous cases of phosgene poisoning. A serious difficulty in the clinical handling of phosgene poisoning cases is a relatively long latent period, up to 12 hours, with no obvious signs of severity. At about 12 hours heavy lung edema appears suddenly, however changes can be seen in routine X-rays taken after only a few hours' exposure (Diller et al., 1969). This study was undertaken to correlate these early changes seen by the roengenologist with morphological alterations in the lungs seen in the'light and electron microscopes.Forty-two adult male and female Beagle dogs were selected for these exposure experiments. Treated animals were exposed to 94.5-107-5 ppm phosgene for 10 min. in a 15 m3 chamber. Roentgenograms were made of the thorax of each animal before and after exposure, up to 24 hrs.

Ultrastructure of Melanin Formation in Curvularia sp., Alternaria sp., and Drechslera Sorokiniana

1977 ◽  
Vol 35 ◽  
pp. 398-399
Author(s):  
M. H. Wheeler ◽  
W. J. Tolmsoff ◽  
A. A. Bell
Keyword(s):  
Potassium Phosphate ◽  
Thielaviopsis Basicola ◽  
Wild Type ◽  
Potassium Phosphate Buffer ◽  
Transmission Microscopy ◽  
Electron Transmission ◽  
Melanin Formation ◽  
Before And After ◽  
Alternaria Sp ◽  
Electron Transmission Microscopy

(+)-Scytalone [3,4-dihydro-3,6,8-trihydroxy-l-(2Hj-naphthalenone] and 1,8-di- hydroxynaphthalene (DHN) have been proposed as intermediates of melanin synthesis in the fungi Verticillium dahliae (1, 2, 3, 4) and Thielaviopsis basicola (4, 5). Scytalone is enzymatically dehydrated by V. dahliae to 1,3,8-trihydroxynaphthalene which is then reduced to (-)-vermelone [(-)-3,4- dihydro-3,8-dihydroxy-1(2H)-naphthalenone]. Vermelone is subsequently dehydrated to DHN which is enzymatically polymerized to melanin.Melanin formation in Curvularia sp., Alternaria sp., and Drechslera soro- kiniana was examined by light and electron-transmission microscopy. Wild-type isolates of each fungus were compared with albino mutants before and after treatment with 1 mM scytalone or 0.1 mM DHN in 50 mM potassium phosphate buffer, pH 7.0. Both chemicals were converted to dark pigments in the walls of hyphae and conidia of the albino mutants. The darkened cells were similar in appearance to corresponding cells of the wild types under the light microscope.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

The Precipitation of Si in AlCuSi Thin Films

1973 ◽  
Vol 31 ◽  
pp. 34-35 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Heat Treatment ◽  
Solid Solution ◽  
Integrated Circuit ◽  
Copper Film ◽  
Solution Concentration ◽  
X Ray ◽  
Silicon Thin Films ◽  
Before And After

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.

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