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In this paper, two kinds of composites constructed by UO3 nanoflakes (which is UO3·yNH3·xH2O, precisely) and different graphene oxide (GO) nanosheets (homemade GO, GO-h, and commercial GO, GO-c) were prepared via solution chemical reaction. The two kinds of GO share similar morphology and possess the same species of functional groups. Nevertheless, GO-h possesses higher oxidization degree and thus could adsorb more uranyl ions, and the corresponding composite shows a much more regular shape: UO3 nanoflakes and GO nanosheets cross each other, which would help overcome the disadvantage of graphene aggregation. As a result, homemade reduced graphene oxide (RGO-h) sheets inside the final UO2 pellets (named as UO2/GO-h) could construct a well-bulit thermally conductive network to enhance its thermal conductivity. However, similar RGO-c network cannot be observed in the UO2/GO-c pellest originated from GO-c. Therefore, only the thermal conductivity of UO2/GO-h pellet acquires a dramatic increase, 37.30% relative to UO2 pellet at 1200 °C, showing that UO2/GO-h possesses great potential for the development of novel UO2-based ATF fuels.

In this study, a novel UO2/SiC nanocomposite pellet was constructed via in-situ hydrothermal synthesis and SPS. Such method could avoid the problem of traditional mechanical mixing that could obtained the molecular level mixing during a chemical process. Using such method, SiC was dispersed uniformly in the UO2 matrix. Its thermal conductivity is significantly higher than those of UO2 pellet fabricated using hydro-thermally prepared powder and traditional UO2 pellets at both working temperature (400 °C) and near-accident temperature (1000 °C). The thermal conductivity of UO2/SiC nanocomposite pellet increased 23.7 % over traditional UO2 and 48.9 % over UO2 pellet fabricated using hydro-thermally prepared powder at 400 °C. It also increased 33.6 % over traditional UO2 and 74.8 % over UO2 pellet fabricated using hydro-thermally prepared powder at 1000 °C. These advantages are expected to maintain high thermal conductivity of fuels, enhance heat transferring efficiency of reactors, and minimize risks of pellet failure in the entire fuel life cycle.

In this article, a novel method to synthesize graphene quantum dots was developed via thermal treatment of crude graphite oxide (GO) in a dry and alkaline condition to cut the crude GO sheets into small graphene quantum dots (named as aGQDs). The aGQDs are nano-scale reduced graphene oxide pieces with the sizes around 5–10 nm. The aGQDs could disperse in water for their richment of oxygen-containing groups. The fluorescence properties were carefully investigated. The aGQDS aqueous solution shows a bright yellow-green fluorescence under the UV illumination. Besides, the uranyl ions show a strong fluorescence quenching effect on the a aGQD aqueous solution even at a low concentration (~10−7 M) compared with other common ions in natural water-body, which makes that these aGQDs could be applied as a chemosensor for detection of uranyl ions with good sensitivity and selectivity., Analytical chemistry; Environmental science; Materials science; Graphene dots; Uranyl; Detection; Fluorescence quenching

In this study, a novel signal-increase electrochemiluminescence (ECL) biosensor has been developed for the detection of glucose based on graphene quantum dot/glucose oxidase (GQD/GO x ) on Ti foil. The proposed GQD with excellent ECL ability is synthesized through a green one-step strategy by the electrochemical reduction of graphene oxide quantum dot. Upon the addition of glucose, GO x can catalytically oxidize glucose and the direct electron transfer between the redox centre of GO x and the modified electrode also has been realized, which results in the bio-generated H 2 O 2 for ECL signal increase in GQD and realizes the direct ECL detection of glucose. The signal-increase ECL biosensor enables glucose detection with high sensitivity reaching 5 × 10 −6 mol l −1 in a wide linear range from 5 × 10 −6 to 1.5 × 10 −3 mol l −1 . Additionally, the fabrication process of such GQD-based ECL biosensor is also suitable to other biologically produced H 2 O 2 system, suggesting the possible applications in the sensitive detection of other biologically important targets (e.g. small molecules, protein, DNA and so on).

Figure S1 A) CVs of the electrolysis of 1.0 mg mL−1 GOQD at a scan rate of 50 mV s−1; B) CVs of Ti foil after GOQD electrolysis in 0.067 M pH~7 PBS.;Figure S2 FTIR spectra of GQD and GOQD.;Figure S3 Raman spectra of GQD and GOQD.;Figure S4 XPS spectra of (A) GOQD and (B) GQD.;Figure S5 Photoluminescence spectra of GOQD/Ti foil, GQD/Ti foil and the supernatant after centrifugation of the GQD/Ti foil.

We report on the facile, reliable fabrication of novel magnetic cucurbit[6]uril/graphene oxide (CB[6]/GO/Fe3O4) composite by using an in-situ co-precipitation method, for which the formation process and possible formation mechanism were also investigated. Moreover, the composite was used as an adsorbent for the removal of uranium(VI) from aqueous solution. Herein, GO nanosheets were chosen as a substrate to immobilize CB[6] and Fe3O4. During the co-precipitation of Fe3O4 nanoparticles on surface of GO nanosheets, CB[6] molecules was fixed through hydrogen bonding simultaneously. The as-prepared composite exhibited a high efficiency of magnetic separability, competitive adsorption performance and acceptable reusability and stability for U(VI) removal, indicating a potential application in uranium-bearing wastewater treatment.

This study aims to understand the complexation of U(VI) with oxydiacetic acid (ODA), iminodiacetic acid (IDA) and thiodiacetic acid (TDA) through density functional theory (DFT) calculations. The structures, complexation stabilities and bonding nature were investigated for U(VI)/XDA complexes (XDA is short for the three ligands). The calculations have proved that tridentate structures are more favorable than terminal bidentate ones for all stoichiometries, and steric hindrance is a factor that cannot be ignored especially for 1:2 complexes. The binding stabilities of the ligands and relative binding groups are in the sequences IDA > ODA ≫ TDA and CO > OH− ≫ H2O > X (Oether, N and S), respectively. All of the coordination bonds exhibit typically ionic character. The coordination bonds are mainly contributed by the interactions of U 5f-orbital and O(C)/X p-orbitals. The strength of all coordination bonds follows the order U–O(C) > U–N > U–O(H2) ≈ U–Oether > U–S. U–S interaction was solidly confirmed by MO and AIM analysis, which is found for U(VI)/TDA complexes for the first time. U–X bonds play an important role in U(VI)/XDA coordination.

Some important thermal properties of both PuO2 and α-Pu2O3 have been investigated by atomic simulation between 298 K and 1500 K using BMH empirical potential and shell potential, including thermal expansion coefficient, entropy, heat capacity and enthalpy. The BMH empirical potential of Pu–O bond in α-Pu2O3 was fitted by GULP program. The calculated values are in good agreement with the experimental data for PuO2, shows that the parameters we selected are appropriate. But especially for α-Pu2O3, these thermal properties were too difficult to be truly measured in experiments because of its radio-toxicity and the high chemical activity. So we could not evaluate our calculated results accurately.

We perform first-principles calculations of electronic structure and optical properties for UO2 and PuO2 based on the density functional theory using the generalized gradient approximation (GGA)+\emph{U} scheme. The main features in orbital-resolved partial density of states for occupied \emph{f} and \emph{p} orbitals, unoccupied \emph{d} orbitals, and related gaps are well reproduced compared to experimental observations. Based on the satisfactory ground-state electronic structure calculations, the dynamical dielectric function and related optical spectra, i.e., the reflectivity, adsorption coefficient, energy-loss, and refractive index spectrum, are obtained. These results are consistent well with the attainable experiments., Comment: 6 pages, 4 figures