scholarly journals Thermostable α-Glucan Phosphorylase-Catalyzed Enzymatic Copolymerization to Produce Partially 2-Deoxygenated Amyloses

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1070
Author(s):  
Jun-ichi Kadokawa ◽  
Shota Nakamura ◽  
Kazuya Yamamoto
Keyword(s):  
Substrate Recognition ◽  
Reaction Medium ◽  
Aquifex Aeolicus ◽  
X Ray Diffraction ◽  
Casting Method ◽  
X Ray ◽  
Amorphous Nature ◽  
Monomer Feed ◽  
Glucan Phosphorylase

α-Glucan phosphorylase catalyzes the enzymatic polymerization of α-d-glucose 1-phosphate (Glc-1-P) monomers from a maltooligosaccharide primer to produce α(1→4)-glucan—i.e., amylose. In this study, by exploiting the weak specificity for the substrate recognition of a thermostable α-glucan phosphorylase (from Aquifex aeolicus VF5), we investigated the enzymatic copolymerization of 2-deoxy-α-d-glucose 1-phosphate (dGlc-1-P), which was produced in situ from d-glucal, with Glc-1-P to obtain non-natural heteropolysaccharides composed of α(1→4)-linked dGlc/Glc units—i.e., partially 2-deoxygenated amylose. The reactions were carried out at different monomer feed ratios using a maltotriose primer at 40 °C for 24 h. The products were precipitated from the reaction medium, isolated by centrifugation, and subjected to 1H NMR spectroscopic and powder X-ray diffraction measurements to evaluate their chemical and crystalline structures, respectively. Owing to its amorphous nature, the partially 2-deoxygenated amylose with adapted unit ratios formed a film when subjected to a casting method.

scholarly journals Hemi-Synthesis of Chiral Imine, Benzimidazole and Benzodiazepines from Essential Oil of Ammodaucus leucotrichus subsp. leucotrichus

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 975 ◽  
Author(s):  
Farid Chebrouk ◽  
Khodir Madani ◽  
Brahim Cherfaoui ◽  
Leila Boukenna ◽  
Mónica Válega ◽  
...  
Keyword(s):  
Essential Oil ◽  
Hplc Analysis ◽  
Reaction Medium ◽  
2D Nmr ◽  
Chiral Hplc ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reaction Proceeds ◽  
Derivatives Of

The hemi-synthesis of chiral imine, benzimidazole and benzodiazepine structures is reported by the condensation of (S)-(−)-perillaldehyde, the major phytochemical of Ammodaucus leucotrichus subsp. leucotrichus essential oil, with different amine derivatives of 2,3-diaminomaleonitrile, o-phenylenediamine and 3-[(2-aminoaryl)amino]dimedone. The reaction proceeds in situ at ambient temperature without prior isolation of the natural (S)-(−)-perillaldehyde. Final products precipitate in the ethanolic reaction medium. 2D NMR and single-crystal X-ray diffraction studies were used to unequivocally characterize the structures in solution and in the solid state, respectively. Chiral HPLC analysis confirms the formation of unique enantiomers and diastereomeric mixtures.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

In-situ Investigation of Bainite Formation with fast X-Ray Diffraction (iXRD)

2017 ◽  
Vol 72 (6) ◽  
pp. 355-364
Author(s):  
A. Kopp ◽  
T. Bernthaler ◽  
D. Schmid ◽  
G. Ketzer-Raichle ◽  
G. Schneider
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Investigation

Texture Evolution Under Fast Heating and Cooling Rates of Zirconium Alloys Studied In-Situ by Synchrotron X-Ray Diffraction

2020 ◽  
Author(s):  
Chi-Toan Nguyen ◽  
Alistair Garner ◽  
Javier Romero ◽  
Antoine Ambard ◽  
Michael Preuss ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Zirconium Alloys ◽  
X Ray Diffraction ◽  
Fast Heating ◽  
Cooling Rates ◽  
X Ray ◽  
Heating And Cooling

STRUCTURAL EVOLUTION OF EXCEPTIONALLY IRON-DEFICIENT HEMATITE NANOCRYSTALS AS OBSERVED BY IN SITU SYNCHROTRON X-RAY DIFFRACTION

2019 ◽  
Author(s):  
Si Athena Chen ◽  
◽  
Peter Heaney ◽  
Jeffrey E. Post ◽  
Peter J. Eng ◽  
...  
Keyword(s):  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Deficient

Hydrolytic products of Fe(III) after oxidation of Fe(II) by chlorate

1982 ◽  
Vol 47 (4) ◽  
pp. 1069-1077 ◽  
Author(s):  
Karel Mádlo ◽  
František Hanousek ◽  
Antonín Petřina ◽  
Jaroslav Tláskal
Keyword(s):  
Electron Microscopy ◽  
Ir Spectroscopy ◽  
Chemical Analysis ◽  
Ferrous Sulphate ◽  
Reaction Medium ◽  
Potassium Chlorate ◽  
X Ray Diffraction ◽  
X Ray

Ferrous sulphate was oxidized by potassium chlorate in the pH region 2-7 and at temperatures ranging from 298.1 to 323.1 K and various hydrolytic products of Fe(III) were separated and indentified. The separated solid ferric products were analyzed using a combination of the chemical analysis, IR spectroscopy, X-ray diffraction, and electron microscopy. The following substances were found as major components of the products: Fe2O3.n H2O ("ferric gel"), Fe2O3.n H2O with bound SO2-4 ions ("sulphogel"), α-FeO(OH), γ-FeO(OH) and Fe3O4. Their amount depends particularly on the pH temperature of the reaction medium.

In situ X-ray diffraction techniques as a powerful tool to study battery electrode materials

2002 ◽  
Vol 47 (19) ◽  
pp. 3137-3149 ◽  
Author(s):  
M. Morcrette ◽  
Y. Chabre ◽  
G. Vaughan ◽  
G. Amatucci ◽  
J.-B. Leriche ◽  
...  
Keyword(s):  
Electrode Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Battery Electrode

scholarly journals In-Situ Synchrotron X-ray Diffraction Investigation of Microstructural Evolutions During Low-Pressure Carburizing

2021 ◽  
Author(s):  
Ogün Baris Tapar ◽  
Jérémy Epp ◽  
Matthias Steinbacher ◽  
Jens Gibmeier
Keyword(s):  
Carbon Content ◽  
Carbon Diffusion ◽  
Low Pressure ◽  
Carbon Accumulation ◽  
Experimental Chamber ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Supply

AbstractAn experimental heat treatment chamber and control system were developed to perform in-situ X-ray diffraction experiments during low-pressure carburizing (LPC) processes. Results from the experimental chamber and industrial furnace were compared, and it was proven that the built system is reliable for LPC experiments. In-situ X-ray diffraction investigations during LPC treatment were conducted at the German Electron Synchrotron Facility in Hamburg Germany. During the boost steps, carbon accumulation and carbide formation was observed at the surface. These accumulation and carbide formation decelerated the further carbon diffusion from atmosphere to the sample. In the early minutes of the diffusion steps, it is observed that cementite content continue to increase although there is no presence of gas. This effect is attributed to the high carbon accumulation at the surface during boost steps which acts as a carbon supply. During quenching, martensite at higher temperature had a lower c/a ratio than later formed ones. This difference is credited to the early transformation of austenite regions having lower carbon content. Also, it was noticed that the final carbon content dissolved in martensite reduced compared to carbon in austenite before quenching. This reduction was attributed to the auto-tempering effect.

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