Bioaccessibility of Metal Cations in Soil Is Linearly Related to Its Water Exchange Rate Constant

2011 ◽  
Vol 45 (9) ◽  
pp. 4139-4144 ◽  
Author(s):  
Brian D. Laird ◽  
Derek Peak ◽  
Steven D. Siciliano
Keyword(s):  
Exchange Rate ◽  
Rate Constant ◽  
Water Exchange ◽  
Metal Cations ◽  
Water Exchange Rate ◽  
Exchange Rate Constant

scholarly journals Evaluation and comparison of diffusion MR methods for measuring apparent transcytolemmal water exchange rate constant

2017 ◽  
Vol 275 ◽  
pp. 29-37 ◽  
Author(s):  
Xin Tian ◽  
Hua Li ◽  
Xiaoyu Jiang ◽  
Jingping Xie ◽  
John C. Gore ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Rate Constant ◽  
Water Exchange ◽  
Water Exchange Rate ◽  
Diffusion Mr ◽  
Exchange Rate Constant

Pressure effect on hydrogen isotope exchange kinetics in chymotrypsinogen investigated by FT-IR spectroscopy

1991 ◽  
Vol 69 (11) ◽  
pp. 1699-1704 ◽  
Author(s):  
P. T. T. Wong
Keyword(s):  
High Pressure ◽  
Exchange Rate ◽  
Rate Constant ◽  
Bound Water ◽  
Pressure Effects ◽  
Protein Molecules ◽  
Fast Exchange ◽  
Exchange Rate Constant ◽  
Hydrogen Deuterium ◽  
Exchange Kinetics

Hydrogen/deuterium (H/D) exchange rate constants in chymotrypsinogen have been determined at several pressures up to 28.9 kbar by FTIR spectroscopy. The secondary structure of the protein molecules was monitored simultaneously at the corresponding pressures by the intensity redistribution of the infrared amide I band at these pressures. As in other proteins, the labile protons on the amide groups in chymotrypsinogen can, to a good approximation, be separated into two classes, each with distinct first order H/D exchange rates constants in the time period from 10 min to ~24 h. The fast exchange rate constant increases while the slow exchange rate constant decreases with increasing pressure. The increase in the fast exchange rate constant at high pressure is largely associated with the pressure-induced unfolding of the protein molecules. At extremely high pressure (12.8 kbar), in addition to the unfolding of protein molecules, pressure induced a distortion and weakening of the hydrogen bonds of the fold protein segments also contribute to an increase in the overall H/D exchange rate. The present results confirm that when chymotrypsinogen is dissolved in D2O, a considerable amount of D2O molecules is bound to the protein molecules on the surface as well as in the interior cavities of the molecules. The H/D exchange takes place between these bound D2O and the protons in the protein molecules. The mechanism of the H/D exchange and the interior dynamics in proteins are discussed on the basis of the present results. Key words: hydrogen/deuterium exchange, exchange kinetics, rate constant, pressure effects, infrared spectroscopy, protein, conformation structure, bound water.

scholarly journals The Direction-Dependence of Apparent Water Exchange Rate in Human White Matter

NeuroImage ◽  
2021 ◽  
pp. 118831
Author(s):  
Zhaoqing Li ◽  
Zhenfeng Pang ◽  
Juange Cheng ◽  
Yi-Cheng Hsu ◽  
Yi Sun ◽  
...  
Keyword(s):  
Exchange Rate ◽  
White Matter ◽  
Water Exchange ◽  
Water Exchange Rate ◽  
Direction Dependence

scholarly journals Study on Water Exchange and Water Quality Simulation of Macao Airport Expansion Project

2021 ◽  
Vol 261 ◽  
pp. 03019
Author(s):  
Huang Pengfei ◽  
Liu Pei ◽  
Xu Wei
Keyword(s):  
Water Pollution ◽  
Water Quality ◽  
Exchange Rate ◽  
Water Exchange ◽  
Exchange Capacity ◽  
Two Dimensional ◽  
Water Exchange Rate ◽  
Water Quality Simulation ◽  
Significant Difference ◽  
Better Than

In this paper, we analyzed the current situation of water pollution sources near Macao airport, established a two-dimensional water exchange and water quality mathematical model near the project, and compared and simulated the reclamation schemes of Macao airport. According to the results of water exchange and COD calculation of water quality, the 80 m channel scheme was remarkably better than the 40 m one in terms of water exchange capacity and the possibility of achieving the water quality target. However, with the increase of channel width, the variation of water exchange rate and half exchange period would slow down. There was no significant difference in water exchange rate, water exchange period and water quality distribution between 80m channel and 120 m channel. The final scheme was to adopt the 80 m channel.

Accelerating water exchange in GdIII–DO3A-derivatives by favouring the dissociative mechanism through hydrogen bonding

2019 ◽  
Vol 55 (4) ◽  
pp. 513-516 ◽  
Author(s):  
Loredana Leone ◽  
David Esteban-Gómez ◽  
Carlos Platas-Iglesias ◽  
Marco Milanesio ◽  
Lorenzo Tei
Keyword(s):  
Hydrogen Bonding ◽  
Exchange Rate ◽  
Water Exchange ◽  
Exchange Mechanism ◽  
Water Molecules ◽  
Dissociative Mechanism ◽  
Water Exchange Rate ◽  
Order Of Magnitude

The water exchange rate in GdIII-complexes increases by one order of magnitude due to H-bonding between the phenol(ate) group and the water molecules involved in the dissociative exchange mechanism.

Unexpectedly Large Change of Water Exchange Rate and Mechanism on [Ln(DTPA-BMA)(H2O)] Complexes along the Lanthanide(III) Series

1995 ◽  
Vol 34 (17) ◽  
pp. 4447-4453 ◽  
Author(s):  
Dirk Pubanz ◽  
Gabriel Gonzalez ◽  
D. Hugh Powell ◽  
Andre E. Merbach
Keyword(s):  
Exchange Rate ◽  
Water Exchange ◽  
Large Change ◽  
Water Exchange Rate

scholarly journals Electronic Effects of the Substituents on Relaxometric and CEST Behaviour of Ln(III)-DOTA-Tetraanilides

Inorganics ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 43
Author(s):  
Valeria Lagostina ◽  
Loredana Leone ◽  
Fabio Carniato ◽  
Giuseppe Digilio ◽  
Lorenzo Tei ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Water Exchange ◽  
Chemical Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
Saturation Transfer ◽  
Electronic Effects ◽  
17O Nmr ◽  
Water Exchange Rate ◽  
Coordinated Water ◽  
The Eu

Three different 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetamide (DOTAM) derivatives bearing as amide N-substituents phenyl, p-methoxyphenyl and p-ethylbenzoate groups were synthesized and the 1H and 17O NMR relaxometric behaviour of the Gd(III)-chelates and chemical exchange saturation transfer (CEST) effect of the Eu(III) complexes were evaluated. The electronic properties of the substituents were shown to strongly influence the coordinated water exchange rate (kex), resulting in five times faster kex for the electron donating phenylmethoxy group compared to the electron withdrawing ethylbenzoate group.

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