作者机构：
[Luo, Juan; Nie, Changming] Univ South China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.;[Lan, Jianhui; Wang, Congzhi; Chai, Zhifang; Zhao, Yuliang; Shi, Weiqun; Wu, Qunyan; Luo, Juan] Chinese Acad Sci, Lab Nucl Energy Chem, Inst High Energy Phys, Beijing 100049, Peoples R China.;[Lan, Jianhui; Wang, Congzhi; Chai, Zhifang; Zhao, Yuliang; Shi, Weiqun; Wu, Qunyan; Luo, Juan] Chinese Acad Sci, Key Lab Biomed Effects Nanomat & Nanosafety, Inst High Energy Phys, Beijing 100049, Peoples R China.;[Chai, Zhifang] Soochow Univ, Sch Radiol & Interdisciplinary Sci RAD X, Suzhou 215123, Peoples R China.;[Chai, Zhifang] Soochow Univ, Collaborat Innovat Ctr Radiat Med Jiangsu Higher, Suzhou 215123, Peoples R China.
通讯机构：
[Nie, Changming] U;[Shi, Weiqun] C;Univ South China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.;Chinese Acad Sci, Lab Nucl Energy Chem, Inst High Energy Phys, Beijing 100049, Peoples R China.;Chinese Acad Sci, Key Lab Biomed Effects Nanomat & Nanosafety, Inst High Energy Phys, Beijing 100049, Peoples R China.
关键词：
density functional theory;di-(2-ethylhexyl) phosphoric acid;actinide;lanthanide;solvent extraction
摘要：
Separation of trivalent lanthanides (Ln(III)) and actinides (An(III)) is a key issue in the advanced spent nuclear fuel reprocessing. In the well-known trivalent actinide lanthanide separation by phosphorus reagent extraction from aqueous komplexes (TALSPEAK) process, the organophosphorus ligand HDEHP (di-(2-ethylhexyl) phosphoric acid) has been used as an efficient reagent for the partitioning of Ln(III) from An(III) with the combination of a holdback reagent in aqueous lactate buffer solution. In this work, the structural and electronic properties of Eu~(3+) and Am~(3+) complexes with HDEHP in nitric acid solution have been systematically explored by using scalar-relativistic density functional theory (DFT). It was found that HDEHP can coordinate with M(III) (M=Eu, Am) cations in the form of hydrogen-bonded dimers HL_2~- (L=DEHP), and the metal ions prefer to coordinate with the phosphoryl oxygen atom of the ligand. For all the extraction complexes, the metal-ligand bonds are mainly ionic in nature. Although Eu(III) complexes have higher interaction energies, the HL_2~- dimer shows comparable affinity for Eu(III) and Am(III) according to thermodynamic analysis, which may be attributed to the higher stabilities of Eu(III) nonahydrate. It is expected that this work could provide insightful information on the complexation of An(III) and Ln(III) with HDEHP at the molecular level.
摘要：
Functionalized magnetic Fe_3O_4@SiO_2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopore channels, aiming to efficiently and conveniently uptake U(VI) from aqueous solution. The resultant material possesses highly ordered mesoporous structure with large surface area, uniform pore size, excellent thermal stability, quick magnetic response, and desirable acids resistance, confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N_2 adsorption/ desorption experiments, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Detailed U(VI) sorption test indicated that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of 160 mg/g at pH 5.0±0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The absorbed U(VI) can be easily desorbed by 0.01 mol/L or more concentrated HNO3 solution, and the reclaimed sorbent can be reused with no obvious decrease of sorption capacity even after 4 sorption-desorption cycles. The present results suggest the vast opportunities of this kind of magnetic composite on the solid-phase extraction of U(VI).
摘要：
Heme proteins perform diverse functions in living systems, of which nitrite reductase (NIR) activity receives much attention recently. In this study, to better understand the structural elements responsible for the NIR activity, we used myoglobin (Mb) as a model heme protein and redesigned the heme active center, by introducing one or two distal histidines, and by creating a channel to the heme center with removal of the native distal His64 gate (His to Ala mutation). UV-Vis kinetic studies, combined with EPR studies, showed that a single distal histidine with a suitable position to the heme iron, i.e., His43, is crucial for nitrite (NO2-) to nitric oxide (NO) reduction. Moreover, creation of a water channel to the heme center significantly enhanced the NIR activity compared to the corresponding mutant without the channel. In addition, X-ray crystallographic studies of F43H/H64A Mb and its complexes with NO2- or NO revealed a unique hydrogen-bonding network in the heme active center, as well as unique substrate and product binding models, providing valuable structural information for the enhanced NIR activity. These findings enriched our understanding of the structure and NIR activity relationship of heme proteins. The approach of creating a channel in this study is also useful for rational design of other functional heme proteins. (C) 2016 Elsevier Inc. All rights reserved.
摘要：
Recently, the computer simulation of molecular imprinted polymer (MIP) has been suggested as a rational method to search for optimal imprinting conditions in environmental science and engineering. In this paper, the sulfisoxazole conformation was optimized and sulfisoxazole and the functional monomers were computed using quantum chemistry method at MP2 level with 6-31++ G* basis set. The binding energy, Delta E, an important parameter for their interactions, was used to select the best functional monomers, and the solvation energy was used to choose the most suitable solvent. The results indicated that the best functional monomer was acrylic acid, the most suitable solvent was carbon tetrachloride, and the most stable molecular model was the hydrogen bond formed between the H18 in sulfisoxazole and the O2 in acrylic acid with 1: 1 molar ratio of SIZ to AA. These results had an insight into the interaction of the sulfisoxazole MIP, which provided theoretical reference for SIZ-MIP.
通讯机构：
[Nie, Chang-Ming] U;Univ South China, Sch Chem & Chem Engn, Hengyang 421001, Peoples R China.
关键词：
Density functional theory;N, N′- bis(3-allyl salicylidene)-o-phenylenediamine;Uranium
摘要：
We used density functional theory calculations at the B3LYP/6-311G** level for a theoretical study on the complex formed when uranium(IV) coordinates with N, N'-bis(3-allyl salicylidene)-o-phenylenediamine (BASPDA), i.e., U(BASPDA)_2. The results indicated that the coordination complex of U(BASPDA)_2 could form two different structures with a ratio of 1:2. One was a parallel dislocation structure (PDS-U), in which the two BASPDAs' middle benzene rings adopted a parallel dislocation with an angle of 56.64°, and the other was a staggered finger ‘‘+'' structure (SFS-U), in which the two BASPDAs employed the staggered finger ‘‘+'' shape. The binding energies, charge distribution, spectral properties, thermodynamic properties, molecular orbitals and Wiberg bond indices for both PDS-U and SFS-U were calculated and compared with each other.
摘要：
Novel group quantitative structure-property relationship (QSPR) models on the thermodynamic properties of PBXTHs were presented, by the multiple linear regression (MLR) analysis method. Four thermodynamic properties were studied: the entropy (S-theta), the standard enthalpy of formation (Delta H-f(theta)), the standard Gibbs energy of formation (Delta(f)G(theta)), and the relative standard Gibbs energy of formation (Delta(R)G(theta)). The results by the formula indicate that the calculated and predicted data in this study are in good agreement with those in literature and the deviation is within the experimental errors. To validate the estimation reliability for internal samples and the predictive ability for other samples, leave-one-out (LOO) cross validation (CV) and external validation were performed, and the results show that the models are satisfactory.
摘要：
To reveal the structure-function relationship of heme proteins, and to provide clues for creating artificial heme proteins with improved functions, we here use myoglobin (Mb) as a model protein, and report that its peroxidase activity can be enhanced by construction of two distal histidines and a channel to the heme pocket. It showed that in addition to a single distal histidine with a suitable distance to the heme iron (Phe43 to His43 mutation), a second distal histidine (Leu29 to His29 mutation) can work cooperatively to increase the turnover number, mimicking the role of well-known His-Arg pair in native peroxidases. Moreover, a channel created to the heme pocket by removal of the native His64 gate (His64 to A1a64 mutation) was shown to facilitate the binding of substrate, resulting in enhanced catalytic efficiency for the triple mutant L29H/F43H/H64A Mb, which is beyond the addition of both double mutants, L29H/H64A Mb and F43 H/H64A Mb. These results provide valuable information for elucidating the structure-function relationship of heme proteins. In addition, this study provides clues for design of artificial heme proteins, and the strategy of creating a channel to the heme active center is expected be extended to design of other artificial enzymes with improved catalytic performance. (C) 2016 Elsevier B.V. All rights reserved.
