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The individually and simultaneously detection of heavy metal ions have been widely reported. However, little analyzed the difference and relationship between the two such as sensitivities and limit of detection (LOD) using irradiated natural materials. Based on the electrochemical detection of Pb(II), Cd(II), Hg(II) and Cu(II) ions, their stripping behaviors, through combining an irradiated attapulgite (IAP) at a fluence of 30 kGy (IAP30) with room temperature ionic liquid (RTIL) composites coated electrodes, were compared and analyzed by square wave stripping voltammetry. The characteristic of sensitivities and LOD of IAP30/RTIL electrode towards metal ions were markedly improved in comparison with IAP electrode. The LOD of the simultaneous detection towards Pb(II), Cd(II), Cu(II) and Hg(II) using IAP30/RTIL electrode were 0.8, 0.5, 0.2 and 0.06 nM, respectively. The sensitivities and LOD of Pb(II), Cd(II) in simultaneous detection were lower and higher than these in individual detection, while those of Hg(II) and Cu(II) increased and decreased in comparison with the individual detection at IAP30/RTIL or IAP30 modified electrode. An enhanced sensitivity of Hg(II) in the simultaneous detection reached 242.4 μA/μM, and was the largest among four metal ions. Analysis of six groups of solutions including Pb(II)-Cd(II)-Hg(II), Cd(II)-Cu(II)-Hg(II), Pb(II)-Cu(II)-Hg(II), Cu(II)-Hg(II), Pb(II)-Hg(II), Cd(II)-Hg(II) were further performed, respectively. This study provided a novel method for the construction of sensitive electrochemical sensors of heavy metal by natural materials, and an effective reference that meet the needs of environmental control for analysis of different metal ions. [ABSTRACT FROM AUTHOR]

The polyethylenimine (PEI) or ethanediamine (EDA) has been employed to adsorb metal ions. However, both the combination of CoFe 2 O 4 -reduced graphene oxide (rGO) with PEI or EDA for the analysis of Cu(II) determination and interaction mechanism towards copper ion by electrochemical method and X-ray photoelectron spectroscopy (XPS) are, to the best of our knowledge, unexplored. The amine functionalized rGO/CoFe 2 O 4 composite were synthesized through a one-pot method, and characterized by electrochemical method and different spectra such as FT-IR, XRD, XPS, etc. The lowest detection limit with 20 pM (3δ method) and sensitivity with 0.39 μA/nM towards Cu(II) was obtained at PEI/rGO/CoFe 2 O 4 modified electrode under optimized condition. The characteristics of Cu(II) on the amine-group functionalized CoFe 2 O 4 /rGO composite were investigated by cyclic voltammetry and XPS. The shifts of O and N peaks of PEI (or EDA)/CoFe 2 O 4 /rGO preconcentrating Cu(II) showed the synergistic effect of CoFe 2 O 4 /rGO and PEI (or EDA) to Cu(II). The analysis indicated that the interaction between the composite and Cu(II) was adsorption control process. The proposed electrode was also employed to the analysis of real soil sample. Thus, the proposed method and interaction mechanism analysis based on adsorption interaction could provide a reference for further investigate the pollution of metal ions. [ABSTRACT FROM AUTHOR]

This study attempts to understand the stripping behaviors and mutual impact of different metal ions in electrochemical detection. A reduced graphene oxide-Fe 3 O 4 (rGO-Fe 3 O 4 ) nanocomposites with small-sized Fe 3 O 4 is prepared by a simple and one-pot synthesis method. The morphology and structure of the nanocomposites are investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectrometer and X-ray diffraction. The electrochemical behaviors of nanocomposite electrode are characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The individual and simultaneous stripping analysis of Cd 2+ , Pb 2+ and Hg 2+ using rGO-Fe 3 O 4 electrode are performed by square wave anodic stripping voltammetry (SWASV) under optimized condition, and experimental data show that there are differences in some parameters such as sensitivities and detection limits, etc. To further understand phenomena, a series of interference tests are systematically evaluated by SWASV in detail. The experimental results demonstrate that determination of Cd 2+ is easy to be influenced by Pb 2+ and Hg 2+ . At last, the proposed electrode is used to analyze content of Pb 2+ in soil sample. The result obtained at the nanocomposite electrode is comparable to that obtained by inductively coupled plasma atomic emission spectroscopy, indicating a good accuracy. The sensor could provide an effective detection and analysis method for heavy metal ions. [ABSTRACT FROM AUTHOR]

A glassy carbon electrode modified with β-cyclodextrin/graphene/1,10-diaminodecane (β-CD–G–DAD) composite was used to detect Di(2-ethyl hexyl) phthalate (DEHP) by electrochemical method. The composite electrode was fabricated by self-assembly method: DAD was grafted to the surface of a glassy carbon electrode (GCE), and graphene oxide (GO) sheets were absorbed on the amine-terminated DAD (GO/DAD), then β-CD could be bound with GO through hydrogen bond (β-CD/GO/DAD), finally β-CD/GO/DAD was electrochemically reduced to β-CD/G/DAD. The DEHP entered into cyclodextrin cavity to form the guest–host complex proven by UV–vis spectra, and the characteristic of β-CD/GO composite was shown by FT-IR spectra. The composite electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The charge resistance value increased linearly with concentration of DEHP in the range of 0.2–1.2 μM, and the detection limit was 0.01 μM (3 σ method). The composite electrode showed good selectivity and stability. [ABSTRACT FROM AUTHOR]

An amine-Fe3O4modified glassy carbon (GC) electrode was constructed for detecting Pb(II) ions in wastewater. The electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Square wave anodic stripping voltammetry (SWASV) was used to detect the Pb(II), and the detection limit of Pb(II) was 0.15 µM. The sensitivity of the electrode to detect Pb(II) was about 10.07 µA/µM, with a correlation coefficient of 0.991, which was approximately 10 times bigger than that of a pure Fe3O4modified electrode. The electrode also showed good selectivity and stability. This results indicated that the amine-magnetite material could have some potential applications in heavy metal ions detection in wastewater. [ABSTRACT FROM PUBLISHER]

[Display omitted] • The Bi 2 O 3 /irradiated attapulgite (IAP) composite is prepared. • The detection of Cd2+ was performed by through laser-induced breakdown spectroscopy (LIBS) with electroanalysis. • The first time in-site detection directly on the electrode towards Cd2+ using LIBS is performed. • The limit of detection by LIBS is 8 pM by electrodeposition. Refactory cadmium ion by continuous accumulation produces a severe threat to human health. It is rather important to early find Cd2+ through an effective method. However, the detection of Cd2+ using laser-induced breakdown spectroscopy (LIBS) or electroanalysis is still faced with many difficulties, such as ultra-trace detection, higher sensitive and very little metal of solid substrate. Herein, we reported a ultra-trace and sensitive detection of Cd2+ based on Bi 2 O 3 40/irradiated attapulgite (IAP) composite by combining electroanalysis with LIBS. The attapulgite was irradiated with high energy ion beam by optimization. The proposed material was applied to accumulate and detect Cd2+ ion using LIBS by electrodeposition (accumulation of negative potential) and electro-adsorption (accumulation of positive potential), especially the accumulation sample was directly detected on the surface of electrode, and thus the limits of detection (LOD) was reduced in comparison with usual method, and the corresponding LOD by electrodeposition and electro-adsorption using LIBS reached 8 and 16 pM, respectively. And the LOD obtained by stripping method was 3 nM. Next, X-ray photoelectron spectroscopy was employed to further analyze the interaction mechanism. The interference has not been found. The proposed method was also applied for the detection of Cd2+ in a real sample. This study indicated that the technique combining electroanalysis with LIBS provided a novel method for the effective detection of other toxic ions. [ABSTRACT FROM AUTHOR]

Angiotensin II has been shown to be a potent agent in the acceleration of wound repair. Angiotensin (1-7), a fragment of angiotensin II that is not hypertensive, was found to be comparable to angiotensin II in accelerating dermal healing. This activity was evaluated in four models: rat and diabetic mouse full-thickness excisional wounds; rat random flap; and guinea pig partial thickness thermal injury. In all models, angiotensin (1-7) was comparable to angiotensin II. Angiotensin (1-7) accelerated the closure of wounds in diabetic mice and rats. In diabetic mice the resultant tissue at day 25 after injury was more comparable to normal tissue than the fibrotic scar observed in placebo-treated wounds. In the random flap model, angiotensin (1-7) was comparable to angiotensin II in maintaining flap viability (approximately 82%) and flap survival (40%). Finally, angiotensin (1-7) increased proliferation in the hair follicles at the edge of the wound and site of thermal injury, and the number of patent blood vessels on day 7 after partial thickness thermal injury. These data may be partially explained by the effect of angiotensin II and angiotensin (1-7) on keratinocyte proliferation. While platelet-derived growth factor had no effect on keratinocyte proliferation, angiotensin II and angiotensin (1-7) significantly increased keratinocyte proliferation. These data show that angiotensin(1-7) is comparable to angiotensin II in accelerating skin repair. Furthermore, the hypertensive and wound healing effects can be separated within the family of angiotensin peptides. [ABSTRACT FROM AUTHOR]

Portable smartphone platform offers a new strategy for on-site and visual quantitative detection of ammonium nitrogen in soil and wastewater samples. [Display omitted] • OPA/K 2 SO 3 /R-QDs and OPA/K 2 SO 3 based sensor have been respectively used for determination of low and high concentration range of NH 4 + via two response modes. • The color responses toward the NH 4 + concentrations have been systematically studied. • The proposed strategy can realize visual quantitative detection of NH 4 + in real samples. • Portable smartphone platform brings great convenience for on-site detection of NH 4 +. Ammonium (NH 4 +) is crucial for plant growth as well as various industrial processes, the accurate and field measurement of the NH 4 + level is of great significance for agricultural precision fertilization and water quality monitoring, but excessive amounts of ammonium can lead to eutrophication of aqueous environments. Herein, the ability of the proposed probe solution and test paper to colorimetric change towards high-concentration NH 4 + and ratiometric fluorescence response to low-concentration NH 4 + has been developed for visual detection of ammonium in real samples. Specifically, high concentration of NH 4 + (0.5–7 mM) could interact with the o-phthalaldehyde (OPA) in presence of K 2 SO 3 , resulting in the colorimetric transition from colorless to wine-red with increasing the NH 4 + concentration. Subsequently, the addition of the red-emitting CdTe QDs (R-QDs) constructed the OPA/K 2 SO 3 /R-QDs ratiometric fluorescent probes for low-concentration NH 4 + (less than 1 mM) sensing with a limit of detection (LOD) down to 18 nM, accompanied by a distinct fluorescence color shift from red to blue under UV light. Furthermore, the visualization detection integrated with smartphone was converted to data information (RGB value) through a Color Recognizer APP and successfully used for visual quantitative identification of NH 4 +. Actually, the proposed probe solution and test paper have been applied to the determination of NH 4 + in soil extracts and wastewater samples. Compared with the standard methods, this established strategy can supply stable and reliable detection results, and allow fast sensing at room temperature, exhibiting great application potential for visual on-site detection of NH 4 + at different concentration ranges in environmental samples. [ABSTRACT FROM AUTHOR]

To improve the performance of enterprise network information security, we proposed a behaviour analytics model that established a unique behaviour pattern for each user and identifies untrusted interactive behaviour. First, a series of behaviour characteristics was constructed by observing user behaviours. These characteristics were then used by a big data analysis method called hidden Markov model to model the behaviour of trusted users. Next, a forward algorithm calculated the probability of observation sequences from users with the same and different positions. Finally, untrusted interactive behaviours were identified by comparing the observation sequence probability sets of trusted and untrusted users. The proposed method was applied to the Enterprise Resource Planning system used by a publishing house to identify the credibility of its user behaviour. The highest false positive rates obtained were 0.74% and 5.26% for users in different positions and the same position, respectively. These results verify that the model is effective in identifying untrusted interactive behaviours. [ABSTRACT FROM AUTHOR]

• Nuclear power construction collaborative quality assurance mode is constructed. • The collaborative interaction behavior among participants is analyzed. • A double-layer GERT network is constructed to represent value transfer and increment. • The quantitative measurement of value of the value chain is realized. • The key quality business and activities that restrict the value-added are explored. Due to the large number of participants and the multi-dimensional heterogeneity of economic activities, the value creation links are hidden and the value relationship is difficult to identify. Only paying attention to the effect and cost input of a single enterprise's quality business cannot maximize the value of collaborative quality control, and cannot meet the requirements of nuclear power intelligent construction. Therefore, we propose to use collaborative quality value to characterize the value creation process and coordinate the interest relationship and value distribution among participants. On this basis, a collaborative quality value chain analysis method based on the double-layer GERT network is studied to quantitatively calculate the collaborative quality value. Specifically, the collaborative quality assurance mode is constructed and the interaction behavior among participants is analyzed. The value transfer and enhancement across participants is represented by the double-layer GERT network model, and the global and local values of the value chain are quantitatively measured based on the equivalent transfer function. Then, the key quality assurance business and activities that restrict the whole chain value-added are explored, and the collaborative quality value-added strategies are proposed. Finally, the effectiveness of this method is verified by a case study involving the fabrication of reactor pressure vessel (RPV) support inside a nuclear power project. This study provides a new method for realizing the value evaluation of collaborative quality control and maximizing the collaborative quality value of the whole value chain. [ABSTRACT FROM AUTHOR]

Abstract It is rather important to not only obtain the better detection efficiency for metal ions, but also investigate the change of sensitivity and detection limit in the simultaneous detection. Herein, a novel type of room temperature ion liquid (RTIL)/γ-AlOOH/Fe(OH) 3 composite was prepared. Both the individual and simultaneous determination of Hg(II) and Cu(II) were examined by the composite electrode. The electrode exhibited the lowest limits of detection (LODs) of 0.5 and 0.3 nM for Hg(II) and Cu(II) in simultaneous determination, the highest sensitivities of 64.5 and 65.9 μA/μM, respectively, and the shortest response time. Both Hg(II) and Cu(II) films electroplated on the surface of composite were used to further analyze change of sensitivity and LOD, respectively. The thickness of films influenced the sensitivity and LOD. The proposed electrode was also performed the analysis of soil sample. The analytic method in this study could open up an avenue for the analysis and detection of metal ions, and provide a reference of electrochemical sensor based on metal films. [ABSTRACT FROM AUTHOR]

An effective and convenient method using ion beam bombardment (IBB) for separating a multi-layered compact graphene oxide (GO) piece into several small few-layered loose pieces was developed, and it was found that those small GO pieces had formed a flower-like structure. Therein, the main mechanism was proposed to be the etching and charge effects of IBB. This work could provide a facile and promising approach for improving the dispersion and the related properties of GO. Furthermore, X-ray diffraction and Raman spectrum determinations demonstrated that, with the increasing fluence, IBB could effectively decrease the chemical groups in the layers of GO, resulting in the decrease of the layer distance. [ABSTRACT FROM AUTHOR]

To address the problems associated with laminated object manufacturing (LOM) using sheet metal as a modeling material, an approach of cutting the sheet metals by a new LOM process and connecting them by diffusion welding technology is proposed. The conventional LOM process and the new LOM process are compared with reference to the theoretical manufacturing error. A slicing algorithm for the new LOM process has been deduced. The conclusions drawn from the experiments and analysis are shrinkage in the stack direction is small; atom diffusion between two joints occurs clearly and new grains form; the shear strength of the welding zone is above 100 MPa; the micro-hardness of the welding zone is almost the same as that of the substrate. The fabrication of sample part suggests that the new LOM process with diffusion welding could be a useful method for the rapid manufacturing of metal parts. [Copyright &y& Elsevier]