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Uncovering the complexation properties of actinides with common organic ligands in aqueous solution is of significant importance to understand the fundamental coordination chemistry of actinides as well as to develop more efficient extractants for actinides separation in advanced nuclear fuel cycles. Herein, the complexation behaviour of hexavalent plutonyl (Pu(VI) or PuO22+) with three dicarboxylic acids, iminodiacetic acid (IDA), N-methyl-iminodiacetic acid (MIDA) and dipicolinic acid (DPA), was studied through both experimental and theoretical approaches. In 1.0 M NaClO4 medium, successive formation of 1 : 1 and 1 : 2 (metal/ligand ratio) complexes of Pu(VI) with IDA and MIDA were identified and their stability constants were determined and compared with those of DPA. The complexation strength varies for the complexes of Pu(VI) with IDA, MIDA and DPA. For the 1 : 1 complexes, the stability constants of Pu(VI) with the three ligands follow the order of IDA < MIDA < DPA, while those of the 1 : 2 complexes follow the order of IDA < DPA < MIDA. The complexation trends are validated by DFT calculations, which suggest that the complexation strength of IDA/MIDA/DPA with Pu(VI) is governed by both the electronic effect (electron withdrawn group or electron donating group) and the rigidity of the ligands. Furthermore, the symmetric features of the Pu(VI) complexes with the three ligands were illustrated by analyzing the optical characteristics of the complexes and DFT calculation. The results provide new insights into the intrinsic mechanism of hexavalent actinide complexation with tridentate dicarboxylic acids in aqueous solutions.

Kandelia obovata (Ko) and Aegiceras corniculatum (Ac) are common and dominant plant species in mangrove wetlands in South China, which are distributed in similar tidal zones along the coastline. The present study aimed to determine the allelopathic effects of leaf litter leachates (LLLs) from Ko and their purified condensed tannins (PCTs) on the germination and growth of Ac by mangrove microcosms. Replicate pots containing five different levels of LLLs and PCTs were separately prepared and propagules of Ac were placed in each treatment. Both LLLs and PCTs significantly inhibited the germination and growth of Ac, especially at high concentrations. The final germination rates of the roots and stems and the numbers of fine roots declined continuously, while other growth indicators, including the lengths of fine roots and nutritive roots and the biomasses of roots, stems, and leaves first increased and then decreased with increasing levels. These results indicate that LLLs from the leaf litter of Ko, in particular their PCTs, exerted an inhibition effect on propagule germination and seedling growth of Ac, and the inhibitory effects were concentration dependent. This study suggested that condensed tannins from leaf litter, acting as allelochemicals, could regulate the natural regeneration of a mangrove forest.

The selective separation of trivalent americium from lanthanides in a nitric acid medium by a tetradentate ligand, N,N′-diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen), in an i...

In this study, the impacts of various illumination intensities on growth, digestion and metabolism as well as antioxidant enzyme dynamics of Takifugu rubripes (0.03 ± 0.01 g) were investigated. Activities of alkaline phosphatase (AKP), acid phosphatase (ACP), pepsin (PPS), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) were measured. Juveniles were reared under four degrees of illumination intensities: 50 mW/m2, 250 mW/m2, 500 mW/m2 and 750 mW/m2, at a constant photoperiod (12D:12 L). Samples were collected at days 7, 14, 21, 28, and 35. After 35 days, the 750 mW/m2 light intensity was found to have significantly increased the final body weight, which was 1.1 ± 0.005 g. On day 35, PPS activities of T. rubripes juveniles in the 750 mW/m2 sample group were significantly low when compared to those of the 250 mW/m2 group while AKP activities in the 750 mW/m2 group were significantly higher than those of the 50 and 500 mW/m2 groups (p 0.05). Even though they were relatively lower, there were no significant differences in SOD activities in the 250 mW/m2 group relative to the 500 and 750 mW/m2 groups. On day 35, high light intensity (750 mW/m2) resulted in stress responses that were characterized by T-AOC activities, and activity values were significantly lower than those of other groups (p

Cu2+ exhibited a good activation effect on specularite. However, its microscopic activation mechanism needs further study. Additionally, Cu2+ was mainly present in the flotation solution as Cu2+, Cu(OH)+, and Cu(OH)2 at pH = 7. Therefore, density functional theory (DFT) calculations were used to investigate the effect of Cu species such as Cu2+, Cu(OH)+, and Cu(OH)2 adsorbed on the crystal structure and properties of the specularite (0 0 1) surface. The adsorption mechanism of different Cu components on the surface was also further clarified by the analyses of the adsorption model, adsorption energy, partial density of states (PDOS), charge transfer, and bond properties. In addition, the obtained results are discussed. Based on the obtained results, it can be concluded that the geometric structure and electronic properties on the surface changed after adsorbing Cu components and that the O3–Fe1–O1 structure was more susceptible to the adsorbates. The adsorption engines results show that Cu components could be spontaneously adsorbed onto the specularite (0 0 1) surface with adsorption energies of −0.76, −0.85, and −1.78 eV, corresponding to Cu2+, CuOH+, and Cu(OH)2, respectively. Therefore, the adsorption stability of the Cu species on the specularite surface increased in the order of Cu2+ &lt, Cu(OH)+ &lt, Cu(OH)2. Additionally, the adsorption sites for Cu species on the surface were different. Cu2+ interacted mainly with O atoms on the surface, forming Cu–O complexes, while Cu(OH)+ and Cu(OH)2 acted mainly through the O atom of –OH, interacting with Fe atoms to form Cu–O–Fe complexes. The formation of Cu–O and Cu–O–Fe complexes increased the adsorption sites for sodium oleate, with more hydrophobic species being generated to improve the floatability of specularite.

Revealing the complexation behavior of high-valent actinides in solutions is of great importance to better understand the fundamental chemistry of actinides as well as to control the separation property of actinides in nuclear fuel cycles. In this work, the complexation of hexavalent actinide cations U(VI), Np(VI), and Pu(VI) with two dipicolinic acid derivatives, 6-(dimethylcarbamoyl)picolinic acid (DMAPA, denoted as HL) and

Recently, phenanthroline-based ligands have received increasing attention due to their excellent separation capabilities for trivalent actinides over lanthanide. In this work, we designed a soft-hard donor combined tetradentate phenanthroline-based extractant, tetraethyl (1,10-phenanthrolin-2,9-diyl)phosphonate (C2-POPhen), for the selective separation of trivalent Am(III) over Ln(III) from HNO3 media. The solvent extraction and complexation behaviors of Am(III) and Ln(III) by C2-POPhen were investigated both experimentally and theoretically. C2-POPhen could selectively extract Am(III) over Eu(III) with an extremely fast extraction kinetics. NMR titration studies suggest that only 1:1 complexes of Ln(III) with C2-POPhen formed in CH3OH in the presence of a significant amount of nitrate, while both 1:1 and 2:1 complexes species could form between C2-POPhen and Ln(III) perchlorate in CH3OH without nitrate ions. The stability constants for the complexation of Am(III) and Ln(III) with C2-POPhen in CH3OH were determined by spectrophotometric titrations and the Am(III) complexes are approximately 1 order of magnitude stronger than those of Ln(III), which is consistent with the extraction results. Theoretical calculations indicate that the Am-N bonds in Am/C2-POPhen complexes possess more covalent characters than the Eu-N bonds in Eu/C2-POPhen complexes, shedding light on the underlying chemical force responsible for the Am/Eu selectivity by C2-POPhen. This work represents the first report utilizing phenanthroline-based phosphonate ligands for selective separation of actinides from highly acidic solutions.

The complexation of hexavalent plutonyl Pu(VI) with N,N,N′,N′-tetramethyl-3-oxa-glutar-amide (TMOGA) and its carboxylate analogs, N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) and oxydiacetic acid (ODA), has been studied in 1.0 M NaClO4 by absorption spectrophotometry and density functional theory (DFT). Both 1 : 1 and 1 : 2 complexes of Pu(VI) with TMOGA, DMOGA and ODA have been identified and their stability constants were obtained and compared with those of hexavalent U(VI) and pentavalent Np(V). The resultant stability constants indicate that the ability of the three ligands to complex with Pu(VI) decreases in the order of ODA > DMOGA > TMOGA. While for one given ligand, the stability constants of both the 1 : 1 and 1 : 2 complexes decrease generally in the order U(VI) > Pu(VI) > Np(V). The trends of the complexation strength have been elucidated by the calculated Mulliken atomic charges of the central metal cations. Furthermore, the coordination modes of the Pu(VI) complexes with TMOGA, DMOGA and ODA have been illustrated by analyses of the optical features of the complexes as well as by DFT calculations. The results demonstrate that the 1 : 2 Pu(VI)/TMOGA complex is centrosymmetric, while the 1 : 2 complexes of Pu(VI) with DMOGA and ODA are non-centrosymmetric. Moreover, different coordination modes have been observed in actinyl complexes with the same ligand, suggesting the structurally similar actinyl ions (U(VI), Pu(VI) and Np(V)) could exhibit quite different coordination behavior due to the variation of cation size and electronic structure.

Objectives This study aimed to evaluate enhanced anticancer activity in vitro and in vivo of luteolin-loaded long-circulating micelles (DTLLMs) formulated. Methods DTLLM was the luteolin formulation prepared with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly (ethylene glycol 2000) (DSPE-PEG2000) and d-α-tocopheryl polyethylene glycol succinate (TPGS) in this study. We performed a systematic comparative evaluation of the antiproliferative effect, cellular uptake, antitumour efficacy and in vivo tumour targeting of these micelles using non-small cell lung cancer (NSCLC) A549 cells. Key findings Results showed that the obtained micelles have a mean particle size of around 42.34 nm, and the size of micelles was narrowly distributed. With the improved cellular uptake, DTLLM displayed a more potent antiproliferative action on A549 cell lines than luteolin; half-maximal inhibitory concentration (IC50) was 7.29 vs 19.14 μg/ml, respectively. The antitumour efficacy test in nude mice showed that DTLLM exhibited significantly higher antitumour activity against NSCLC with lesser toxic effects on normal tissues. The imaging study for in vivo targeting demonstrated that the long-circulating micelles formulation achieved targeted drug delivery and make drug release slow to prolong the circulating time. Conclusion DTLLM might be a potential antitumour formulation.

Screening of strains for improvement in the yields of the desired steroid as well as production of novel steroid is highly demanded. In this study, a filamentous fungus Aspergillus oryzae capable of transforming steroid efficiently was screened from the collection of fresh bark of south China. A novel transformation product was purified, crystallized, and determined as [13, 17β-]furan-17-hydroxyl-4-gonene-3one by single-crystal X-ray diffraction. At the end of the transformation, the yields of the product reached to 95 %, which indicated A. oryzae can be efficiently applied in the field of steroid biotransformation with the novel biocatalytic ability.