High-Performance Selective Excitation Pulses for Solid- and Liquid-State NMR Spectroscopy

ChemPhysChem ◽  
2004 ◽  
Vol 5 (6) ◽  
pp. 834-850 ◽  
Author(s):  
Mikhail Veshtort ◽  
Robert G. Griffin
Keyword(s):  
Nmr Spectroscopy ◽  
Liquid State ◽  
High Performance ◽  
Selective Excitation

Effect of the Mg3N2 Sub-Micron Particle on the Grain Refinement of AZ80 Alloy

2022 ◽  
Vol 327 ◽  
pp. 45-53
Author(s):  
Jiehua Li ◽  
Maria Pammer ◽  
Ernst Neunteufl ◽  
Peter Schumacher
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Refinement ◽  
Liquid State ◽  
High Performance ◽  
Great Loss ◽  
Micron Particle ◽  
Deformation Ability ◽  
Semi Solid ◽  
Az80 Alloy

AZ80 alloy has been widely used to produce high performance Mg casting and wrought parts for high-end applications due to its high mechanical properties and deformation ability. However, at least two important issues still need to be solved in order to further improve its mechanical properties and deformation ability. Firstly, the grain size of α-Mg in AZ80 alloy is relatively large (more than 1000 µm) due to a lack of efficient grain refinement methodologies. Secondly, the size of the eutectic Mg17Al12 phase is also large and the distribution of the eutectic Mg17Al12 phase is continuous, which is very harmful for the mechanical properties, in particular to elongation. In this paper, these two important issues are investigated by adding Mg3N2 sub-micron particle into AZ80 alloy and thereby refining the α-Mg and the eutectic Mg17Al12 phase. Firstly, the Mg3N2 sub-micron particle was directly added into AZ80 alloy by using mechanically stirring in the semi-solid state, subsequently the melting temperature was increased above the liquidous temperature, and finally the melting was casted in the liquid state. It was found that the grain size of α-Mg can be refined from 883.8 µm to 169.9 µm. More importantly, the eutectic Mg17Al12 phase was also refined and the distribution became discontinuous. It should be noted that directly adding the Mg3N2 sub-micron particle into AZ80 alloy leads to a great loss of the Mg3N2 sub-micron particle due to the weak wetting behavior between the Mg3N2 sub-micron particle and Mg melt. The second methodology through mixing Mg3N2 sub-micron particles with AZ91 chips using a twin extruder was also used to prepare AZ91 master alloy with 3wt.% Mg3N2 sub-micron particle, which was subsequently added into AZ80 alloy in the liquid state. In this way, a significant grain refinement of α-Mg and a simultaneous refinement of the eutectic Mg17Al12 phase in AZ80 alloy was also achieved. The grain size of α-Mg can be refined from 883.8 µm to 325.9 µm. However, no significant grain refinement by using UST was observed. Instead, the grain size increases from 325.9 µm to 448.6 µm, indicating that the Mg3N2 sub-micron particle may lose its grain refinement potency due to possible aggregation and clustering. This paper provides an efficient and simple methodology for the grain refinement of α-Mg and the simultaneous refinement of the eutectic Mg17Al12 phase in AZ80 alloy.

scholarly journals Development of an Efficient Protocol for Cimifugin Isolation from Peucedanum schottii and Evaluation of Enzyme Inhibitory Activity

2016 ◽  
Vol 11 (8) ◽  
pp. 1934578X1601100
Author(s):  
Ewelina Kozioł ◽  
Ilkay Erdogan Orhan ◽  
F. Sezer Senol ◽  
Kalina Alipieva ◽  
Milen Georgiev ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Ethyl Acetate ◽  
Crude Extract ◽  
Inhibitory Activity ◽  
High Performance ◽  
Performance Counter ◽  
Inhibitory Potential ◽  
Counter Current ◽  
First Time ◽  
Analytical Scale

The dichloromethane (DCM) extract of the fruits of Peucedanum schottii Besser ex DC. (Apiaceae) was subjected to high-performance counter-current chromatography (HPCCC) for the efficient and fast separation (30 min) and isolation of cimifugin using an ethyl acetate: water (1:1 v/v, K = 1.01) system. The analytical scale-optimized separation was easily scaled to semi-preparative conditions. Cimifugin (11.25% yield, 96.5% purity) was isolated for the first time from P. schottii and characterized by NMR spectroscopy. Cimifugin and the crude DCM extract were evaluated using ELISA microtiter assays for their inhibitory potential against the cholinesterases (acetylcholinesterase - AChE and butyrylcholinesterase - BChE), and tyrosinase (TYR), which are key enzymes for the treatment of some neurodegenerative diseases, i.e. Alzheimer's and Parkinson's. The crude extract exhibited a weak inhibitory activity against AChE, BChE, and TYR (4.2, 35.5, and 0% at 100 μg mL−1 and 10.3, 40.0, and 12.2% at 200 μg mL−1, respectively), while cimifugin displayed low to moderate inhibition towards AChE and BChE (3.1 and 21.6%, respectively) at 200 μg mL−1.

scholarly journals Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

2019 ◽  
Vol 15 ◽  
pp. 1339-1346
Author(s):  
Sven Götz ◽  
Andreas Schneider ◽  
Arne Lützen
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Nmr Spectroscopy ◽  
High Performance ◽  
Chiral Stationary Phase ◽  
Hplc Separation ◽  
Promising Alternative ◽  
Isolation And Characterization ◽  
C Nmr

The preparative resolution of a trifunctionalized C 3-symmetrical chiral cyclotriveratrylene derivative was achieved via high-performance liquid chromatography (HPLC) on a chiral stationary phase. This approach is a promising alternative to the previously reported resolution through formation of diastereomeric esters because it involves fewer synthetic steps and is less prone to thermal (re)racemization. During these studies an intermediate saddle conformer could also be isolated and characterized by 1H and 13C NMR spectroscopy. The HPLC separation method was further developed in order to allow investigations on the racemization behavior of the cyclotriveratrylene derivative.

Dynamics in the p38α MAP Kinase–SB203580 Complex Observed by Liquid-State NMR Spectroscopy

2008 ◽  
Vol 47 (19) ◽  
pp. 3548-3551 ◽  
Author(s):  
Valerie S. Honndorf ◽  
Nicolas Coudevylle ◽  
Stefan Laufer ◽  
Stefan Becker ◽  
Christian Griesinger
Keyword(s):  
Nmr Spectroscopy ◽  
Map Kinase ◽  
Liquid State ◽  
P38α Map Kinase

Analysis of Acid-Soluble Glycogen in Pork Extracts of TwoPRKAG3Genotypes by1H Liquid-State NMR Spectroscopy and Biochemical Methods

2011 ◽  
Vol 59 (22) ◽  
pp. 11895-11902 ◽  
Author(s):  
Flemming H. Larsen ◽  
Birgitta Essén-Gustavsson ◽  
Marianne Jensen-Waern ◽  
René Lametsch ◽  
Anders H. Karlsson ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Liquid State ◽  
Biochemical Methods
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