scholarly journals Research on chemical exchange process of boron isotope separation

2011 ◽  
Vol 18 ◽  
pp. 151-156 ◽  
Author(s):  
Yiping Huang ◽  
Shuang Cheng ◽  
Jiao Xu ◽  
Weijiang Zhang
Keyword(s):  
Chemical Exchange ◽  
Isotope Separation ◽  
Exchange Process ◽  
Boron Isotope

Phosphorus(V) oxoacid derivatives as efficient ligands for boron isotope separation by chemical exchange method

2014 ◽  
Vol 457 (2) ◽  
pp. 141-143
Author(s):  
A. V. Lizunov ◽  
E. I. Goryunov ◽  
I. B. Goryunova ◽  
A. V. Khoroshilov ◽  
A. A. Semenov ◽  
...  
Keyword(s):  
Chemical Exchange ◽  
Isotope Separation ◽  
Boron Isotope ◽  
Exchange Method

Study on Pyrolysis Reaction of Boron Isotope Separation

2012 ◽  
Vol 554-556 ◽  
pp. 584-590
Author(s):  
Zhou Chen ◽  
Wei Jiang Zhang ◽  
Jiao Xu ◽  
Xiao Ling Wang
Keyword(s):  
Chemical Exchange ◽  
Isotope Separation ◽  
Industrial Applications ◽  
Boron Isotope ◽  
Experimental Setup ◽  
Optimal Temperature ◽  
Pyrolysis Reaction

Nowadays in China, excessive import of boron isotope has always been the bottleneck to its industrial applications in nuclear, mechanical, steel and electronic fields. To pull the boron industry out of the mire of import, it is prerequisite to study the enriching and refining of boron isotope. In this work, we present an experimental setup of boron isotope separation by chemical exchange distillation with focus on pyrolysis reaction. After repeated tests, the optimal temperature of pyrolysis reaction (i.e., 140oC) had been found and the best enrichment of 10B (i.e., 34.4%) could be achieved when the reaction continued to the 8th day. These results indicate that the more completely the pyrolysis reaction performs, the better enrichment of 10B arrives.

scholarly journals Metal–organic frameworks (MOFs) as highly efficient agents for boron removal and boron isotope separation

RSC Advances ◽  
2017 ◽  
Vol 7 (26) ◽  
pp. 16022-16026 ◽  
Author(s):  
Jiafei Lyu ◽  
Hongxu Liu ◽  
Jingshuang Zhang ◽  
Zhouliangzi Zeng ◽  
Peng Bai ◽  
...  
Keyword(s):  
Separation Factor ◽  
Isotope Separation ◽  
Metal Organic Frameworks ◽  
Boron Isotope ◽  
Boron Removal ◽  
Boron Uptake ◽  
Highly Efficient ◽  
Metal Organic ◽  
High Boron

A variety of MOFs were observed with ZIF-8, to our knowledge, showing the highest boron uptake and MIL-101(Cr) with an unprecedentedly high boron isotope separation factor.

scholarly journals Study of the coordination of quinuclidine to a chiral zinc phthalocyanine dimer

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1224-1232 ◽  
Author(s):  
Nelson Giménez-Agulló ◽  
Gemma Aragay ◽  
José Ramón Galán-Mascarós ◽  
Pablo Ballester
Keyword(s):  
Chemical Exchange ◽  
Variable Temperature ◽  
Exchange Process ◽  
Zinc Phthalocyanine ◽  
Hydrogen Atoms ◽  
Dimerization Constant ◽  
H Nmr ◽  
Dimerization Process ◽  
Nmr Titrations ◽  
Millimolar Concentration

We attempted the calculation of an accurate equilibrium constant for the dimerization process of enantiomerically pure Zn-1 using UV-vis dilution experiments. At millimolar concentration Zn-1 is involved in a chemical exchange process between its monomeric and dimeric state that is slow on the 1H NMR timescale. We performed variable-temperature 1H NMR experiments in CDCl3 solution to determine the dimerization constant value at different temperatures and performed a van’t Hoff plot to derive the thermodynamic parameters of the process. The calculated thermodynamic data revealed that the dimerization process is entropy-driven and enthalpically opposed. We also probed the coordination of quinuclidine, 1-azabicyclo[2.2.2]octane, 2, to the Zn-1 using UV-vis and 1H NMR titrations in CDCl3 solution. At micromolar concentration the Zn-1 exclusively exists in solution as a monomer and forms a simple 1:1, [Formula: see text], complex with quinuclidine having a stability constant of [Formula: see text]([Formula: see text]) [Formula: see text] 106 M[Formula: see text]. On the other hand, the 1H NMR titrations carried out at 298 K and at millimolar concentration showed that Zn-1 was present in solution as the dimer and formed 1:2, [Formula: see text], and 2:2, [Formula: see text] complexes by coordination to 2. In addition, the 1:1 complex, [Formula: see text] showed a reduced dimerization constant compared to the uncoordinated parent monomer Zn-1. At high quinuclidine concentration, the 1:1 complex, [Formula: see text], derived from the coordinated dimer dissociation was also detected. The 1H NMR spectra of the titrations displayed separate signals for some hydrogen atoms of the Zn-phthalocyanine in each one of the four species. Remarkably, the chemical exchange processes involving free and bound quinuclidine in the monomeric and dimeric complexes showed different kinetics on the NMR timescale.

Design of a Mixer Settler Plant for Isotope Separation by Chemical Exchange

1995 ◽  
Vol 110 (2) ◽  
pp. 220-227 ◽  
Author(s):  
David A. White ◽  
Fathurrachman
Keyword(s):  
Chemical Exchange ◽  
Isotope Separation

The A39G FF domain folds on a volcano-shaped free energy surface via separate pathways

2021 ◽  
Vol 118 (46) ◽  
pp. e2115113118
Author(s):  
Ved P. Tiwari ◽  
Yuki Toyama ◽  
Debajyoti De ◽  
Lewis E. Kay ◽  
Pramodh Vallurupalli
Keyword(s):  
Free Energy ◽  
Chemical Exchange ◽  
Exchange Process ◽  
Conformational Dynamics ◽  
Chemical Exchange Saturation Transfer ◽  
Folding Kinetics ◽  
Free Energy Surface ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Energy Surfaces

Conformational dynamics play critical roles in protein folding, misfolding, function, misfunction, and aggregation. While detecting and studying the different conformational states populated by protein molecules on their free energy surfaces (FESs) remain a challenge, NMR spectroscopy has emerged as an invaluable experimental tool to explore the FES of a protein, as conformational dynamics can be probed at atomic resolution over a wide range of timescales. Here, we use chemical exchange saturation transfer (CEST) to detect “invisible” minor states on the energy landscape of the A39G mutant FF domain that exhibited “two-state” folding kinetics in traditional experiments. Although CEST has mostly been limited to studies of processes with rates between ∼5 to 300 s−1 involving sparse states with populations as low as ∼1%, we show that the line broadening that is often associated with minor state dips in CEST profiles can be exploited to inform on additional conformers, with lifetimes an order of magnitude shorter and populations close to 10-fold smaller than what typically is characterized. Our analysis of CEST profiles that exploits the minor state linewidths of the 71-residue A39G FF domain establishes a folding mechanism that can be described in terms of a four-state exchange process between interconverting states spanning over two orders of magnitude in timescale from ∼100 to ∼15,000 μs. A similar folding scheme is established for the wild-type domain as well. The study shows that the folding of this small domain proceeds through a pair of sparse, partially structured intermediates via two discrete pathways on a volcano-shaped FES.

Isotope Separation by Chemical Exchange: A Computer Simulation

1991 ◽  
Vol 96 (3) ◽  
pp. 337-345 ◽  
Author(s):  
Heinrich R. Obermoller ◽  
David A. White
Keyword(s):  
Computer Simulation ◽  
Chemical Exchange ◽  
Isotope Separation

Modeling a Chemical Exchange Process for the 13C Isotope Enrichment

2015 ◽  
Vol 772 ◽  
pp. 27-32 ◽  
Author(s):  
Zoltan Kovendi ◽  
Vlad Mureşan ◽  
Mihail Abrudean ◽  
Iulia Clitan ◽  
Mihaela Ligia Ungureşan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Process Modeling ◽  
Process Simulation ◽  
Control Structure ◽  
Chemical Exchange ◽  
Exchange Process ◽  
Open Loop ◽  
Isotope Enrichment ◽  
Isotope Concentration ◽  
Made In

This paper presents a solution for modeling a chemical exchange process carbon dioxide (CO2) – carbamate for the 13C isotope enrichment. A big difficulty in the process modeling procedure is the fact that it is a non-linear one. In order to solve this problem, an original modeling solution that permits the process simulation for the entire domain of the values of the input signal is used. The process modeling is made in order to include it in an automatic control structure of the 13C isotope concentration. Some relevant simulations of the open loop process are presented, both in the case when the disturbances do not occur and the case when they occur in the system.

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