scholarly journals Role of Organic Phosphates and Phosphonates in Catalyzing Dynamic Exchange Reactions in Thiol‐Click Vitrimers

2021 ◽  
pp. 2100072
Author(s):  
Khadijeh Moazzen ◽  
Elisabeth Rossegger ◽  
Walter Alabiso ◽  
Usman Shaukat ◽  
Sandra Schlögl
Keyword(s):  
Exchange Reactions ◽  
Organic Phosphates ◽  
Dynamic Exchange

scholarly journals F/OH ratio in a rare fluorine-poor blue topaz from Padre Paraíso (Minas Gerais, Brazil) to unravel topaz’s ambient of formation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
N. Precisvalle ◽  
A. Martucci ◽  
L. Gigli ◽  
J. R. Plaisier ◽  
T. C. Hansen ◽  
...  
Keyword(s):  
Supercritical Fluids ◽  
Fluorine Content ◽  
Minas Gerais ◽  
Hydroxyl Groups ◽  
Exchange Reactions ◽  
Silicate System ◽  
Mullite Phase ◽  
Anomalous Water

AbstractTopaz [Al2SiO4(F,OH)2] is one of the main fluorine-bearing silicates occurring in environments where variably acidic (F)/aqueous (OH) fluids saturate the silicate system. In this work we fully characterized blue topaz from Padre Paraíso (Minas Gerais, Brazil) by means of in situ synchrotron X-Ray and neutron powder diffraction measurements (temperature range 298–1273 K) combined with EDS microanalyses. Understanding the role of OH/F substitution in topaz is important in order to determine the hydrophilicity and the exchange reactions of fluorine by hydroxyl groups, and ultimately to characterize the environmental redox conditions (H2O/F) required for mineral formation. The fluorine content estimated from neutron diffraction data is ~ 1.03 a.f.u (10.34 wt%), in agreement with the chemical data (on average 10.0 wt%). The XOH [OH/(OH + F)] (0.484) is close to the maximum XOH value (0.5), and represents the OH- richest topaz composition so far analysed in the Minas Gerais district. Topaz crystallinity and fluorine content sharply decrease at 1170 K, while mullite phase starts growing. On the basis of this behaviour, we suggest that this temperature may represent the potential initial topaz’s crystallization temperature from supercritical fluids in a pegmatite system. The log(fH2O/fHF)fluid (1.27 (0.06)) is coherent with the fluorine activity calculated for hydrothermal fluids (pegmatitic stage) in equilibrium with the forming mineral (log(fH2O/fHF)fluid = 1.2–6.5) and clearly different from pure magmatic (granitic) residual melts [log(fH2O/fHF)fluid < 1]. The modelled H2O saturated fluids with the F content not exceeding 1 wt% may represent an anomalous water-dominant / fluorine-poor pegmatite lens of the Padre Paraíso Pegmatite Field.

Introduction of photolatent bases for locally controlling dynamic exchange reactions in thermo‐activated vitrimers

2021 ◽  
Author(s):  
David Reisinger ◽  
Simon Kaiser ◽  
Elisabeth Rossegger ◽  
Walter Alabiso ◽  
Bernhard Rieger ◽  
...  
Keyword(s):  
Exchange Reactions ◽  
Dynamic Exchange

A first-principles study of the atomic layer deposition of ZnO on carboxyl functionalized carbon nanotubes: the role of water molecules

2021 ◽  
Vol 23 (5) ◽  
pp. 3467-3478
Author(s):  
J. I. Paez-Ornelas ◽  
H. N. Fernández-Escamilla ◽  
H. A. Borbón-Nuñez ◽  
H. Tiznado ◽  
Noboru Takeuchi ◽  
...  
Keyword(s):  
First Principles ◽  
Ligand Exchange ◽  
Functional Group ◽  
Atomic Layer ◽  
High Reactivity ◽  
Water Molecules ◽  
Exchange Reactions ◽  
Layer Deposition ◽  
The Right

Atomic description of ALD in systems that combine large surface area and high reactivity is key for selecting the right functional group to enhance the ligand-exchange reactions.

scholarly journals Parallelotopia: Ottoman transcultural memory assemblages in contemporary art practices from the Middle East

2019 ◽  
Vol 12 (5) ◽  
pp. 493-513
Author(s):  
Gabriel Koureas
Keyword(s):  
Ottoman Empire ◽  
Contemporary Art ◽  
Ethnic Violence ◽  
Late Nineteenth Century ◽  
Ethnic Communities ◽  
The Past ◽  
Art Practices ◽  
Etel Adnan ◽  
Dynamic Exchange

This article engages with the conversations taking place in the photographic space between then and now, memory and photography, and with the symbiosis and ethnic violence between different ethnic communities in the ex-Ottoman Empire. It questions the role of photography and contemporary art in creating possibilities for coexistence within the mosaic formed by the various groups that made up the Ottoman Empire. The essay aims to create parallelotopia, spaces in the present that work in parallel with the past and which enable the dynamic exchange of transcultural memories. Drawing on memory theory, the article shifts these debates forward by adopting the concept of ‘assemblage’. The article concentrates on the aesthetics of photographs produced by Armenian photographic studios in Istanbul during the late nineteenth century and their relationship to the present through the work of contemporary artists Klitsa Antoniou, Joanna Hadjithomas, Khalil Joreige and Etel Adnan as well as photographic exhibitions organised by the Centre for Asia Minor Studies, Athens, Greece.

Role of sterics in phosphine-ligated gold clusters

2019 ◽  
Vol 21 (4) ◽  
pp. 1689-1699 ◽  
Author(s):  
Katherine A. Parrish ◽  
Mary King ◽  
Marshall R. Ligare ◽  
Grant E. Johnson ◽  
Heriberto Hernández
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Ligand Exchange ◽  
Gold Clusters ◽  
Solution Phase ◽  
Ionization Mass ◽  
Exchange Reactions ◽  
The Stability ◽  
Insight Into

This study examined the solution-phase exchange reactions of triphenylphosphine (PPh3) ligands on Au8L72+ (L = PPh3) gold clusters with three different tolyl ligands using electrospray ionization mass spectrometry to provide insight into how steric differences in the phosphines influence the extent of ligand exchange and the stability of the resulting mixed-phosphine clusters.

scholarly journals A mitochondrial monocarboxylate transporter in rat liver and heart and its possible function in cell control

1975 ◽  
Vol 148 (1) ◽  
pp. 41-47 ◽  
Author(s):  
J Mowbray
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Mitochondrial Membrane ◽  
Pyruvate Dehydrogenase Complex ◽  
Animal Experiments ◽  
Kinetic Studies ◽  
Monocarboxylate Transporter ◽  
Keto Acid ◽  
Exchange Reactions ◽  
Transport Inhibitors

Several hydroxy- and keto-substituted monocarboxylates were found to undergo co- as well as counter-exchange across the mitochondrial membrane. The results argue against a simple Donnan system and may be explained by the existence of a transporter for monocarboxylates. In support of this explanation it was apparently possible to ‘pump’ pyruvate to the sucrose-inaccessible space by using the dicarboxylate transporter. Further, several aromatic and aliphatic analogues of pyruvate, but not of di- or tri-carboxylate transport inhibitors, have been shown to prevent pyruvate-exchange reactions. Palmitoylcarnitine was found to have a much stronger affinity for the carrier than either carnitine or pyruvate and the possible consequences of this for carnitine-palmitoylcarnitine exchange and on the control of the pyruvate dehydrogenase complex are explored. In view of the range of transport inhibitors and substrates it is suggested that the carrier has a fairly broad specificity. ‘Inhibitor-stop’ kinetic studies show that the speed of translocation of pyruvate at 1 degrees C is of the same order as malate. The possible correlation between the role of a hydroxy-keto acid transporter in substrate exchange and some whole animal experiments is briefly discussed. It is proposed that for reasons of control the cell will require membrane monocarboxylate transporters no less than di- or tri-carboxylate carriers.

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