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•Carboxyl functionalized Ti3C2Tx MXene (TCCH) was synthesized.•The stability of the TCCH in water was significantly improved compared with raw Ti3C2Tx.•The optimized TCCH showed ...superior U(VI) and Eu(III) adsorption capacities up to 334.8 mg/g and 97.1 mg/g, respectively.•The adsorption mechanism was associated with inner-sphere surface complexation and electrostatic interaction.
With the development of nuclear power, the negative environmental impact such as radioactive pollution has become an urgent issue to impede the utilization of nuclear energy. The construction of promising organic-inorganic hybrid materials is considered as an effective strategy for environmental remediation of radioactive contamination. In this work, two-dimensional transition metal carbide (MXene), an emerging inorganic layered material, has been successfully modified by carboxyl terminated aryl diazonium salt to both enhance its chelating ability to radionuclides and improve its water stability. The carboxyl functionalized Ti3C2Tx MXene (TCCH) shows excellent removal ability for U(VI) and Eu(III), evidenced by ultrafast adsorption kinetics (3 min), high maximum adsorption capacities (344.8 mg/g for U and 97.1 mg/g for Eu) and high removal percentage of radionuclides from artificial groundwater (> 90%). The adsorption of U(VI) and Eu(III) on TCCH are in good accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. Ionic strength experiments, X-ray photoelectron spectroscopy (XPS) and Extended X-ray absorption fine structure (EXAFS) analyses were conducted to assess the detailed adsorption mechanism. The results reveal that the adsorption of U(VI) on TCCH follows an inner-sphere configuration, whereas the adsorption of Eu(III) is determined by both inner-sphere complexation and electrostatic interaction.
Graphene is an optical material of unusual characteristics because of its linearly dispersive conduction and valence bands and the strong interband transitions. It allows broadband light-matter ...interactions with ultrafast responses and can be readily pasted to surfaces of functional structures for photonic and optoelectronic applications. Recently, graphene-based optical modulators have been demonstrated with electrical tuning of the Fermi level of graphene. Their operation bandwidth, however, was limited to about 1 GHz by the response of the driving electrical circuit. Clearly, this can be improved by an all-optical approach. Here, we show that a graphene-clad microfiber all-optical modulator can achieve a modulation depth of 38% and a response time of ∼2.2 ps, limited only by the intrinsic carrier relaxation time of graphene. This modulator is compatible with current high-speed fiber-optic communication networks and may open the door to meet future demand of ultrafast optical signal processing.
Organizational environmental sustainability depends primarily on employees’ organizational citizenship behavior for the environment (OCBE), and leadership plays an important role in improving and ...inhibiting employees’ OCBE. The purpose of the present study is to examine the mediation process by which abusive supervision affects employees’ OCBE through a daily diary study and to explore the boundary conditions of the relationship between daily moral disengagement and daily OCBE. We collected data from 112 Chinese employees for 10 consecutive days. The results show that daily abusive supervision has a significant negative effect on daily OCBE and that daily moral disengagement plays a significant mediating role in this relationship. In addition, the negative effect of daily moral disengagement on daily OCBE could be attenuated by a psychological green climate. Our findings support our hypotheses and offer useful theoretical and practical implications for promoting OCBE.
The purpose of this study was to explore the dynamic and intervention mechanisms of daily abusive experience affecting daily work engagement. Drawing on conservation of resources (COR) theory, we ...examine the effect of daily abusive supervision on daily work engagement through daily negative emotions from the resource consumption perspective, and the moderation effect of coworker support from the resource provision perspective. Using a daily diary approach and based on a sample of 73 employees for 5 consecutive days in China. The results reveal that daily abusive supervision has a significant negative effect on daily work engagement, daily negative emotions mediate this relationship, and coworker support had a cross-level moderating effect between daily abusive supervision and daily negative emotions. Our study shows ways to boost employees’ daily work engagement and especially ways buffer the negative effect of abused experience on work engagement.
Novel rod-like ternary nanoscale layered double hydroxides (Ca-Mg-Al-LDH) and their bimetal derivatives (Ca-Mg-Al-LDOx, x: 200, 300, 400, 500, and 600 °C) were fabricated with a simple-green ...hydrothermal and calicination process. The interaction mechanism and adsorption property of U(VI) on Ca-Mg-Al-LDH and Ca-Mg-Al-LDOx were investigated by a batch technique and spectroscopy analysis, and the results indicated that U(VI) could form strong and stable surface complexes on Ca-Mg-Al-LDH and Ca-Mg-Al-LDOx surfaces. The adsorption capacity of U(VI) on various adsorbents could be controlled and adjusted through changing the calcination temperature, which was attributed to the different contents of various metal–oxide bonds (e.g., Ca–O, Mg–O, and Al–O). The adsorption capacities of U(VI) on these adsorbents were in the order of Ca-Mg-Al-LDO500 (486.8 mg/g) > Ca-Mg-Al-LDO600 (373.4 mg/g) > Ca-Mg-Al-LDO400 (292.5 mg/g) > Ca-Mg-Al-LDO300 (260.0 mg/g) > Ca-Mg-Al-LDO200 (223.5 mg/g) > Ca-Mg-Al-LDH (132.5 mg/g), which might be attributed to more active surface sites and abundant “Ca–O and Al–O” with the increase of calcination temperature. The results of kinetic and thermodynamic studies demonstrated that the adsorption was a spontaneous and endothermic chemical process, and the better fitted Sips model revealed that the adsorption reaction was multilayer adsorption at low concentration of U(VI) and monolayer adsorption at high concentration of U(VI). This study provided highlights on the interaction mechanism of U(VI) with various metal–oxide bonds, and it could play an important role for the controllable adsorption capacity and effcient application in environmental remediation.
Developing a fluorescent probe for UO22+, which is resistant to interference from other ions such as Cu2+ and can be applied in acidic and high-water systems, has been a major challenge. In this ...study, a “turn-off” fluorescent probe for triamine-modified flavonoid derivatives, 2-triphenylamine-3-hydroxy-4H-chromen-4-one (abbreviated to HTPAF), was synthesized. In the solvent system of dimethyl sulfoxide:H2O (abbreviated to DMSO:H2O) (v/v = 5:95 pH = 4.5), the HTPAF solution was excited with 364 nm light and showed a strong fluorescence emission peak at 474 nm with a Stokes shift of 110 nm. After the addition of UO22+, the fluorescence at 474 nm was quenched. More importantly, there was no interference in the presence of metal ions (Pb2+, Cd2+, Cr3+, Fe3+, Co2+, Th4+, La3+, etc.), especially Cu2+ and Al3+. It is worth noting that the theoretical model for the binding of UO22+ to HTPAF was derived by more detailed density functional theory (DFT) calculations in this study, while the coordination mode was further verified using HRMS, FT-IR and 1HNMR, demonstrating a coordination ratio of 1:2. In addition, the corresponding photo-induced electron transfer (PET) fluorescence quenching mechanism was also proposed.
With the increasing demand of nuclear power plant, the depleted uranium is inevitably emitted and causes environmental risk, hence it is crucial to develop new methods to efficiently eliminate ...uranium compounds from water. In this work, a bifunctional material core-shell-shell layered double hydroxide (LDH) decorated hollow magnetic polydopamine (MP) microspheres (defined as MPL) were synthesized and evaluated for the cleanup of uranium (VI) from aqueous solutions through specific adsorption. The experimental results showed that the adsorption was significantly affected by pH value rather than ionic strength, reflecting that the interaction was mainly governed by inner-sphere surface complexation owing to the multiple functional groups including imine, catechol, amine, and hydroxyl groups. The adsorption kinetics can be perfectly depicted by the pseudo-second-order model with high uptake percentage of 94.8%, which was superior to the previously reported materials. Interestingly, the maximum adsorption performance can be tuned by changing the thickness of polydopamine shell and the content of LDH, in the order of MP2L2 (344 mg/g) > MP2L3 (291 mg/g) > MP3L2 (245 mg/g) > MP2L1 (211 mg/g) > ML2 (142 mg/g) > MP1L2 (141 mg/g) > MP2 (71 mg/g) > Fe3O4 (34 mg/g) at 298.15 K and pH 5.0. The adsorption mechanism has been thoroughly investigated with techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), thermo-gravimetric analyses (TGA), Fourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). In summary, the bifunctional material could be applied as promising building block for the enrichment and recovery of uranium (VI) from aqueous solutions in environmental pollution cleanup.
A novel bifunctional material (MP2L2) synthesized by a facile and green method was applied for removal of U(VI). Display omitted
•A novel bi-functional layered double hydroxide (LDH) decorated hollow magnetic polydopamine (MP) microspheres were synthesized.•The as-prepared functional materials can be applied for efficient remove U(VI) from aqueous solutions, with high uptake percentage of 94.8%.•The adsorption of U(VI) and interaction were mainly governed by inner-sphere surface complexation owing to the multiple functional groups.•Adsorption kinetics can be perfectly simulated by the pseudo-second-order model, the maximum adsorption performance can be tuned.
With the fast development of nanoscience and nanotechnology, the nanomaterials have attracted multidisciplinary interests. The high specific surface area and large numbers of oxygen-containing ...functional groups of graphene oxides (GOs) make them suitable in the preconcentration and solidification of radionuclides from wastewater. In this paper, mainly based on the recent work carried out in our laboratory, the efficient elimination of radionuclides using GOs and GO-based nanomaterials as adsorbents are summarized and the interaction mechanisms are discussed from the results of batch techniques, surface complexation modeling, spectroscopic analysis and theoretical calculations. This review is helpful for the understanding of the interactions of radionuclides with GOs and GO-based nanomaterials, which is also crucial for the application of GOs and GO-based nanomaterials in environmental radionuclide pollution management and also helpful in nuclear waste management.
Uranium was not only the main source of nuclear energy but also one of the long-lived radionuclide.Herein, a novel arginine modified hydroxyapatite carbon microsphere composites（defined as C@HAp/Arg） ...obtained promptly via a one-step mild hydrothermal method, was applied to remove U（Ⅵ） from aqueous solutions. Based on the characterization of transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier transformed infrared spectroscopy（FT-IR）, X-ray diffraction（XRD）and X-ray photoelectron spectroscopy（XPS）, the synthesized C@HAp/Arg presented globular morphology and abundant functional groups（e.g., —COO-）, which were beneficial to its combination with U（Ⅵ）. The interaction mechanism and removal capability of U（Ⅵ） on C@HAp/Arg were studied by batch adsorption technique and spectroscopy analysis. The results implied that U（Ⅵ） can form strong surface complexes on C@HAp/Arg. The kinetics adsorption of U（Ⅵ） followed pseudo-second-order kinetic model with high removal efficiency（$95% within 5h at pH 5.0）. The adsorption isotherms were well fitted by Langmuir model, implying that U（Ⅵ） uptake on C@HAp/Arg was monolayer coverage. It was found that the maximum adsorption capacities of CSs, C@HAp and C@HAp/Arg toward U（Ⅵ） were calculated to be 23.16,72.09 and 569.66 mg/g, respectively, at 298.15 K and pH 5.0, and thermodynamic parameters revealed that the adsorption processes of U（Ⅵ） were spontaneous and endothermic. In addition, effect of co-existed ions and CO32-concentrations demonstrated that U（Ⅵ） adsorption on C@HAp/Arg was weakly interfered by foreign ions and carbonate concentrations. More importantly, the adsorption performance of U（Ⅵ） on C@HAp/Arg was still over $87% after five cycles. Therefore, it was noted that the versatile C@HAp/Arg could be potentially used as a powerful building block for the enrichment and disposal of U（Ⅵ） from aqueous solutions, which could efficiently reduce the potential toxicity of U（Ⅵ） in the U（Ⅵ）-contaminated water.
The tumour microenvironment is a highly heterogeneous entity that plays crucial roles in cancer progression. As the most prominent stromal cell types, cancer-associated fibroblasts (CAFs) produce a ...variety of factors into the tumour microenvironment. In the present study, we firstly isolated CAFs from tumour tissues of the patients with ovarian cancer and demonstrated that the hepatocyte growth factor (HGF) was highly expressed in the supernatants of CAFs. CAF-derived HGF or human recombinant HGF promoted cell proliferation in human ovarian cell lines SKOV3 and HO-8910 cells. Western blotting analysis also showed that CAF-derived HGF or recombinant HGF activated c-Met/phosphoinositide 3-kinase (PI3K)/Akt and glucose-regulated protein 78 (GRP78) signalling pathways in ovarian cancer cells, and these effects could be abrogated by anti-HGF and c-Met inhibitor INCB28060. Moreover, HGF in CAF matrix attenuated paclitaxel (PAC)-caused inhibition of cell proliferation and increase in cell apoptosis through activating c-Met/PI3K/Akt and GRP78 pathways in SKOV3 and HO-8910 cells. The results
were further validated in nude mice. These findings suggest that CAF-derived HGF plays crucial roles in cell proliferation and drug resistance in ovarian cancer cells.
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