Preparation and characterization of kaolinite nanostructures: reaction pathways, morphology and structural order

Clay Minerals ◽  
2015 ◽  
Vol 50 (3) ◽  
pp. 329-340 ◽  
Author(s):  
Balázs Zsirka ◽  
Erzsébet Horváth ◽  
Éva Makó ◽  
Róbert Kurdi ◽  
János Kristóf
Keyword(s):  
Mechanical Treatment ◽  
Potassium Acetate ◽  
Reaction Pathways ◽  
Sodium Polyacrylate ◽  
Tetraalkylammonium Salt ◽  
Structural Order ◽  
Dry Grinding ◽  
Interlamellar Space ◽  
Tubular Morphology

AbstractClay-based nanostructures were prepared from kaolinites of varying structural order by two different methods. In the first method the kaolinite-urea precursor, obtained by dry grinding, was intercalated further with triethanolamine and the tetraalkylammonium salt was synthesized in the interlamellar space. Exfoliation was achieved by the use of sodium polyacrylate (PAS). In the second method, the kaolinite-potassium acetate (kaolinite-KAc) precursor, obtained via two different methods, was intercalated further with ethylene glycol (EG) and then n-hexylamine (HA). Intercalation with EG was also achieved by heating either directly or with microwaves. The morphology that results depends on the method of precursor preparation, the method of heat treatment and the degree of structural order of the original clay. Higher structural order facilitates the formation of a tubular morphology, while mechanical treatment and microwave agitation may result in broken tubes. Molecular mechanical (MM) calculations showed that organo-complexes may be exfoliated to a d value of 10–11 Å.

Preparation and characterization of kaolinite nanostructures: reaction pathways, morphology and structural order

nano Online ◽  
2017 ◽  
Author(s):  
Balázs Zsirka ◽  
Erzsébet Horváth ◽  
Éva Makó ◽  
Róbert Kurdi ◽  
János Kristóf
Keyword(s):  
Reaction Pathways ◽  
Structural Order

Purification and Characterization of Tissue-Type Plasminogen Activator in Maxillary Mucosa with Chronic Inflammation

1985 ◽  
Vol 54 (02) ◽  
pp. 485-489 ◽  
Author(s):  
Yukiyoshi Hamaguchi ◽  
Masuichi Ohi ◽  
Yasuo Sakakura ◽  
Yasuro Miyoshi
Keyword(s):  
Plasminogen Activator ◽  
Chronic Inflammation ◽  
Gel Filtration ◽  
Potassium Acetate ◽  
Tissue Type ◽  
Purification And Characterization ◽  
Tissue Type Plasminogen Activator ◽  
Urokinase Inhibitor ◽  
Type Plasminogen Activator

SummaryTissue-type plasminogen activator (TPA) was purified from maxillary mucosa with chronic inflammation and compared with urokinase. Purification procedure consisted of the extraction from delipidated mucosa with 0.3M potassium acetate buffer (pH 4.2), 66% saturation of ammonium sulfate, zinc chelate-Sepharose, concanavalin A-Sepharose and Sephadex G-100 gel filtration chromatographies.The molecular weight of the TPA was approximately 58,000 ± 3,000. Its activity was enhanced in the presence of fibrin and was quenched by placental urokinase inhibitor, but not quenched by anti-urokinase antibody. The TPA made no precipitin line against anti-urokinase antibody, while urokinase did.All these findings indicate that the TPA in maxillary mucosa with chronic inflammation is immunologically dissimilar to urokinase and in its affinity for fibrin.

Reaction Pathways to 2-Aminothiophenes and Thiophene-3-carbonitriles

2009 ◽  
Vol 62 (5) ◽  
pp. 402 ◽  
Author(s):  
Luigi Aurelio ◽  
Bernard L. Flynn ◽  
Peter J. Scammells
Keyword(s):  
Comparative Studies ◽  
Reaction Pathway ◽  
Reaction Pathways ◽  
Synthesis And Characterization ◽  
The Past ◽  
Adenosine A1 ◽  
Unexpected Reaction ◽  
Potential Applications ◽  
A1 Receptor

Over the past two decades 2-amino-3-benzoylthiophenes have been found to act as allosteric enhancers of the adenosine A1 receptor (A1AR). As such, compounds of this type have potential applications in the therapy of a variety of disorders by enhancing A1AR activation. Initial studies in this field identified various 2-amino-3-benzoylthiophenes as potential leads and of these PD 81723 1a has become the benchmark for comparative studies due to its favourable ratio of allosteric enhancement to antagonism. Surprisingly the synthesis and characterization of PD 81723 1a has not been previously reported. Herein we report the synthesis and characterization of this important A1AR allosteric enhancer. As part of this study we also found an unexpected reaction pathway to 2-phenylthiophene-3-carbonitriles.

scholarly journals Luminescence reveals variations in local structural order of calcium carbonate polymorphs formed by different mechanisms

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Michael B. Toffolo ◽  
Giulia Ricci ◽  
Luisa Caneve ◽  
Ifat Kaplan-Ashiri
Keyword(s):  
Infrared Spectroscopy ◽  
Calcium Carbonate ◽  
Construction Materials ◽  
Reference Database ◽  
Formation Processes ◽  
X Ray Diffraction ◽  
Structural Order ◽  
Lime Plaster ◽  
Calcium Carbonate Polymorphs

Abstract In nature, calcium carbonate (CaCO3) in the form of calcite and aragonite nucleates through different pathways including geogenic and biogenic processes. It may also occur as pyrogenic lime plaster and laboratory-precipitated crystals. All of these formation processes are conducive to different degrees of local structural order in CaCO3 crystals, with the pyrogenic and precipitated forms being the least ordered. These variations affect the manner in which crystals interact with electromagnetic radiation, and thus formation processes may be tracked using methods such as X-ray diffraction and infrared spectroscopy. Here we show that defects in the crystal structure of CaCO3 may be detected by looking at the luminescence of crystals. Using cathodoluminescence by scanning electron microscopy (SEM-CL) and laser-induced fluorescence (LIF), it is possible to discern different polymorphs and their mechanism of formation. We were thus able to determine that pyrogenic calcite and aragonite exhibit blue luminescence due to the incorporation of distortions in the crystal lattice caused by heat and rapid precipitation, in agreement with infrared spectroscopy assessments of local structural order. These results provide the first detailed reference database of SEM-CL and LIF spectra of CaCO3 standards, and find application in the characterization of optical, archaeological and construction materials.

Reactions of [(dmpe)2MnH(C2H4)]: synthesis and characterization of manganese(i) borohydride and hydride complexes

2020 ◽  
Vol 49 (29) ◽  
pp. 9983-9994
Author(s):  
Jeffrey S. Price ◽  
Declan M. DeJordy ◽  
David J. H. Emslie ◽  
James F. Britten
Keyword(s):  
Reaction Pathways ◽  
Synthesis And Characterization ◽  
Hydride Complexes

Reactions of trans-[(dmpe)2MnH(C2H4)] with hydroboranes and phosphines afforded manganese(i) borohydride and hydride complexes; reaction pathways, structures and bonding are discussed.

scholarly journals Parallel reaction pathways and noncovalent intermediates in thymidylate synthase revealed by experimental and computational tools

2018 ◽  
Vol 115 (41) ◽  
pp. 10311-10314 ◽  
Author(s):  
Svetlana A. Kholodar ◽  
Ananda K. Ghosh ◽  
Katarzyna Świderek ◽  
Vicent Moliner ◽  
Amnon Kohen
Keyword(s):  
Thymidylate Synthase ◽  
Critical Role ◽  
Chemical Mechanism ◽  
Reaction Pathways ◽  
Computational Tools ◽  
Isolation And Characterization ◽  
Dna Biosynthesis ◽  
Energy Surfaces ◽  
Covalent Intermediate

Thymidylate synthase was one of the most studied enzymes due to its critical role in molecular pathogenesis of cancer. Nevertheless, many atomistic details of its chemical mechanism remain unknown or debated, thereby imposing limits on design of novel mechanism-based anticancer therapeutics. Here, we report unprecedented isolation and characterization of a previously proposed intact noncovalent bisubstrate intermediate formed in the reaction catalyzed by thymidylate synthase. Free-energy surfaces of the bisubstrate intermediates interconversions computed with quantum mechanics/molecular mechanics (QM/MM) methods and experimental assessment of the corresponding kinetics indicate that the species is the most abundant productive intermediate along the reaction coordinate, whereas accumulation of the covalent bisubstrate species largely occurs in a parallel nonproductive pathway. Our findings not only substantiate relevance of the previously proposed noncovalent intermediate but also support potential implications of the overstabilized covalent intermediate in drug design targeting DNA biosynthesis.

Shape-Controlled Synthesis and Characterization of CuS Crystal from a Low Temperature Hydrothermal Route

2008 ◽  
Vol 47-50 ◽  
pp. 903-906
Author(s):  
Li Fei Chen ◽  
Hua Qing Xie ◽  
Yang Li ◽  
Wei Yu
Keyword(s):  
Hexagonal Phase ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
X Ray ◽  
Near Ir ◽  
Electron Microscope Analysis ◽  
Shape Controlled ◽  
Tubular Morphology

Copper sulfide (CuS) nanocrystals with flower-like and tubular morphology have been successfully synthesized via a facile and convenient hydrothermal route at 75 °C by using CuCl2·2H2O as Cu-precursor, C2H5NS as S-source and CTAB as template molecules. The effect of concentration of reactants and template molecules on morphology has been discussed. X-ray diffraction pattern suggests that the CuS crystals are pure hexagonal phase. The morphology of the products has been studied by scanning electron microscope analysis. The absorption peaks of CuS in UV and near-IR regions indicate that the as-prepared CuS are promising in the development of photoelectric devices.

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