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In recent years, the social Internet of Things (SIoT) and its applications have developed rapidly and introduced convenience to people's lives. In view of the massive amount of information generated by the SIoT, it is necessary to model and analyze the communication among smart devices and study the impact of social attributes of smart devices on information dissemination. Therefore, in this study, we propose a layered information dissemination model for SIoT that abstracts the communication process in SIoT as the information dissemination process among nodes, describes the process of wireless communication in SIoT using the microscopic Markov chain method, and derives the information dissemination threshold based on theoretical analyses. In addition, this study proposes a dynamic cache strategy considering the influence of social attributes, such as user interestingness, information popularity, and the interaction between messages on communication. Finally, the correctness of the model and propagation threshold and the effectiveness of the caching strategy are verified by simulation experiments in artificial networks and real networks. [ABSTRACT FROM AUTHOR]

The geochemical characteristics and potential controlling factors of colloidal Zn, Cd, and Pb in Huanghe (Yellow) River estuary (HRE), China were investigated. The three metals were highly variable over a range of spatiotemporal scales, comprehensively forced by various physical and biological processes. Total dissolved Zn, Cd, and Pb varied from 200.1 to 321.7, 2.6 to 4.1, and 0.5 to 1.0 nmol/L, respectively. Only one near-estuarine station of Zn had contamination factor values >1, which indicate the lower contaminant levels. Five dissolved species of Zn, Cd and Pb were fractionated, namely <1 kDa, 1–3 kDa, 3–10 kDa, 10–100 kDa, and 100 kDa–0.45 µm. The <1 kDa truly dissolved phase was the main fraction of the three dissolved metals (50%–62%), while the 100-kDa–0.45-µm high molecular weight colloidal fraction was dominant in their respective colloidal phase. Territorial input and sediment acted as important sources of strong ligands and natural colloids for the HRE water system. <3-kDa Zn and Pb were susceptible to the dissolved oxygen, the behaviors of colloidal Zn and 3–10-kDa Pb were related to dissolved organic carbon (DOC). However, no significant correlation between each dissolved fraction of Cd and salinity, pH, temperature, colloidal organic carbon, and DOC was found in this study. Overall, these findings, completed by the evaluation of the dissolved species of Zn, Cd, and Pb at 10 sites over the river-sea mixing zone, provided new insights into the colloidal heterogeneity that affect metals geochemical features, migration and fate in estuaries. [ABSTRACT FROM AUTHOR]

An electrochemical sensor constructed by intercalated composites was developed for determination of heavy metal ions. The intercalated composites were composed of hydrosulphonyl functional covalent organic frameworks (COF-SH) and graphene (G). The presence of numerous adsorption sites, such as 18 sulfur atoms and 30 nitrogen atoms per big circle of COFs on COF-SH, was beneficial for the accumulation of heavy metals, while the graphene enhanced the electrical conductivity. The obtained sensor under the optimal conditions successfully detected the presence of heavy metal ions in coastal water samples at concentrations ranging from 1 to 1000 μg L−1. The detection limits of Cd (II), Pb (II), Cu (II), and Hg (II) were 0.3, 0.2, 0.2, and 1.1 μg L−1, respectively. Furthermore, the sensor still exhibited good stability after multiple uses less than 5%. When it is used in the analysis of actual samples, the recovery of standard addition is higher than 95%. In sum, the combination of hydrosulphonyl functional COFs with graphene looks very promising for the assembly of sensors with high sensitivity toward the determination of heavy metal ions for coastal environmental monitoring. [ABSTRACT FROM AUTHOR]

Metal species and the degree of environmental pollution are related to the hydrogen sulfide (H2S), an important product of early diagenesis that can react with metals to form stable compounds. To investigate the effects of H2S to metals and evaluate metal environment effect in the sediments of the East China Sea (ECS) and Yellow Sea (YS), geochemical characteristic and spatial distribution of nine heavy metals and H2S profile were studied. Higher H2S content and lower metal content was observed in the sediments 10 cm in depth in the North Yellow Sea and the west coast of South Korea. The pollution load index (Ipl) indicates that the southern coast of Shandong Peninsula underwent moderate pollution (Ipl=1) of heavy metals and no heavy metal pollution appeared in other areas (Ipl<1). To some extents, the ecological risk of Cd and As enrichment was moderately severe in all stations. The chance of heavy metal combination to be toxic in ECS and YS during summer was 21%. In addition, correlation between H2S content and metals in both solid and porewater phases was obvious, corroborating important effect of H2S on metal distribution. Moreover, H2S could affect the spatial distributions of heavy metals in porewater directly and be indicative of potential biological effects of combined toxicant groups in the study region. [ABSTRACT FROM AUTHOR]

Detection and quantification of heavy metals in soil samples are significant in terms of environmental monitoring and risk assessment for metals. In order to improve the accuracy and precision to detect heavy metal, in this study, four standard samples (NASS-4, NASS-5, NASS-9, and NASS-16) were analyzed by evolving heating (electric heating plate, water bath, and microwave) and acidic systems (includes HCl, HNO3, HF, and HClO4). The result shows that different pretreatment methods have different effects on the extraction of heavy metal elements and five heavy metal elements (Cu, Zn, Pb, Ni, and Cr) were selected for optimization through pretreatment methods. Although the contents of heavy metals were same but we found diversity in the results. Under optimal conditions, the selected standard samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and atomic absorption spectroscopy (AAS), and the results were compared. The results show that different elements have their own most suitable detection methods, such as for Pb, the most suitable method is ICP-MS; and for Zn, the most suitable method is AAS. Pretreatment methods and detection techniques are combined to find and improve accuracy of results for certain elements. This study provides a reliable detection method for the accurate detection of heavy metals in the environment. [ABSTRACT FROM AUTHOR]

Contrast-based photoacoustic imaging is an emerging imaging technology that gold nanoparticles (a kind of photoacoustic contrast agent with a size of 100 nm) are injected into blood vessels for photoacoustic imaging. Image reconstruction is a critical step in photoacoustic imaging, due to the fact that limitations and incompleteness of photoacoustic imaging data of image reconstruction are equivalent to the linear inverse problems. The photoacoustic data is transferred to IOT based on the platform of MATLAB and is quickly processed through the regularization method of Krylov space (the widely used method is LSQR). In order to solve the problem of Krylov space uncertainty, Krylov space dimension selection, and the minimum mismatch of the LSQR objective function (the limitation of LSQR algorithm) of LSQR algorithm, a KRLODPLSMR-GCV3DC algorithm is proposed to solve the above problems in this paper.In this study, the raw photoacoustic data was obtained by injecting gold nanoparticles into capillaries and subcutaneous veins of the palm, and the KRLODPLSMR-GCV3DC algorithm was verified to solve the limitations of LSQR algorithm through four groups of experiments. [ABSTRACT FROM AUTHOR]

Unlike similar works, Xingxue Cushu 性學觕述 (General Introduction to the Learning on [Human] Nature) by the Italian Jesuit missionary Giulio Aleni (1582–1649) sought to deliver the Christian doctrine into China by introducing Western medicine. The conflict between the Christian concept of the soul and the traditional psychic concept in China made the task difficult. Scholasticism rejects the idea that an individual's soul may be physically divided or localized, whereas the Chinese tradition largely assumes the contrary and regards the heart as the center of one's psychic powers or vitality. Aleni addressed this conflict by reducing the mind to the function of the brain for sensitive memory. Chinese physicians accepted Aleni's concept of brain-related memory. However, his claim of an immaterial soul was ignored, and the Western connection between brain and memory was misinterpreted and subjected to Chinese cardiocentrism; thus, the physically centered psychic concept that underlies Chinese philosophy persisted. [ABSTRACT FROM AUTHOR]

The behavior, effects, and toxicity of an element often depend largely on its speciation. In this study, the speciation of copper (Cu) in seawater was investigated via the fixed-point determination of electroactive Cu, acid-dissolved Cu, inert Cu, and total dissolved Cu using a voltammetric method with an electrochemical sensor. This method was found to be simple and effective for speciation analysis as no complicated pretreatment or separation steps were required, permitting its use for the direct determination of Cu speciation in real water samples with confirmed accuracy. Moreover, following simple electrolytic cleaning, the sensor exhibited good measurement stability and reproducibility when it was reused. Fixed-point determinations of electroactive Cu, acid-dissolved Cu, inert Cu, and total dissolved Cu in local seawater were carried out for 15 days. The total dissolved Cu concentration ranged from 45.03 to 122.85 nM, and its average concentration was 66.05 nM. The speciation of Cu was influenced by external environmental changes to some extent but was observed to remain relatively constant. The correlations between the concentrations of different Cu species and environmental parameters are discussed here in detail. [ABSTRACT FROM AUTHOR]

Different species of trace heavy metals (HMs) in seawater samples were simultaneously analyzed by anodic stripping voltammetric method, an analytical technique that does not require sample pre-concentration or the addition of reagents. The effects of the crucial parameters, deposition potential and time, on the determination of HMs were investigated. Concentrations of the total dissolved, dissolved active, and dissolved inert HMs were obtained through different analysis processes. The three species of Cu, Pb, Cd and Zn in seawater samples collected in different locations across Sishili Bay, North Yellow Sea, China were studied. The relative concentration of the dissolved active Cu, Pb, Cd and Zn in the total dissolved concentrations is 59.0%, 69.6%, 87.3% and 84.1%, respectively. The concentrations of different HMs species in Sishili Bay could be affected by the discharged effluent, sea current, and uptake of marine organism. [ABSTRACT FROM AUTHOR]

Medical argumentation in non-Western societies has attracted little attention. In line with the pragma-dialectical approach to the study of argumentation, this article identifies a prototypical argumentative pattern in Chinese medical consultations. In addition to institutional preconditions, whose relevance to the argumentative pattern has been well cited, a factor that may be equally important has remained unnoticed: the preference for certain drugs, treatments or therapeutic measurements on the basis of folk interpretations of medical phenomena in individual ethnic groups. These preferences may be seen as cultural preferences in the medical domain. In this paper, a prototypical argumentative pattern of Chinese medical consultations is provided. Two levels of the pattern are distinguished and discussed: a basic argumentative pattern as presented in the pragmatic-dialectical approach and its extensions due to cultural preferences as well as institutional constraints. Illustrated by an exemplary analysis on the basis of empirical data collected from Chinese consulting rooms, the impact of cultural preferences on physicians’ strategic maneuvering in argumentation is identified and recognized. It is argued that the existence and impact of cultural preferences require attention in medical argumentation. [ABSTRACT FROM AUTHOR]

The article describes the synthesis of bismuth nanosheets (BiNSs) in the presence of a small quantity of graphene oxide (GO) which is helpful for the formation of two-dimensional BiNSs and improves dispersity. The material, when placed on a glassy carbon electrode (GCE), is shown to enable catalytic stripping voltammetric determination of total dissolved iron without the need for adding a complexing agent. The average thickness and length of the BiNSs are 3 to 4 nm and 100 to 200 nm, respectively. The unique nanostructure of the BiNSs, the ability of Bi to form alloys with metal, and the current amplification of the catalytic system make the modified GCE an excellent choice for electrochemical determination of Fe(III). Under the optimal conditions, the electrode has a linear response to Fe(III) in the 0.01 to 20 μM concentrations range, with a lower detection limit of 2.3 nM. The electrode was successfully applied to the sensitive determination of Fe(III) in coastal waters. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The novel gel composite, based on the ground of ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF) and titanium carbide (TiC) nanoparticles, was used to modify glassy carbon electrode and applied to the electrochemical determination of tryptophan (trp). The physical and electrochemical characterizations of the BMIMPF-TiC gel modified electrode were studied in detail by scanning electron microscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry, and differential pulse voltammetry methods. Due to the large specific surface area and strong adsorption property of TiC nanoparticles, as well as the good ionic conductivity and strong electrocatalytic property of BMIMPF, the oxidation peak current of trp at BMIMPF-TiC gel modified electrode showed good linear relation with its concentrations ranging from 0.50 to 30 μmol/L and 30 to 500 μmol/L, respectively. The detection limit was 0.053 μmol/L. More importantly, the BMIMPF-TiC gel modified electrode had good anti-interference ability and can be successfully applied in the electrochemical determination of trp in real food samples. [ABSTRACT FROM AUTHOR]

Two biosorbents were prepared using bamboo powder modified with mercaptoacetic acid and carbon disulfide, which exhibits strong adsorption properties for Cu and Ni. The obtained materials were characterized by FTIR. Maximum adsorption for both metals was found to occur around pH 5.0-6.5. The kinetic data followed the pseudo-second-order model. The maximum adsorption capacities of Cu and Ni on mercaptoacetic acid modified bamboo powder determined from Langmuir isotherm were 103.97mg g and 61.35mg g, respectively. While on carbon disulfide modified bamboo powder were 128.21mg g and 56.82mg g, respectively. The adsorption mechanism analysis revealed that the most possible adsorption mode of Cu was coordination, and Ni was ion exchange. The obtained adsorbents could effectively remove Cu and Ni from industrial electroplating wastewater and could be used repeatedly for more than five cycles. [ABSTRACT FROM AUTHOR]

A nanocomposite, prepared from reduced graphene oxide (rGO), Methylene Blue (MB) and gold nanoparticles (AuNPs), was used to modify a glassy carbon electrode for the determination of total dissolved iron by differential pulse voltammetry. The use of rGO warrants a larger electrode surface and the presence of more active sites, while electron transfer is accelerated by incorporating AuNPs. MB acts as an electron mediator, as an anchor for the AuNPs (which were grown in situ), and also prevents the aggregation of rGO. The modified electrode displayed a remarkably improved sensitivity and selectivity for Fe(III). The kinetics of the electrode reaction is adsorption-controlled, and the reversible process involves one proton and one electron. The response to Fe(III) is linear in the 0.3 to 100 μM concentration range, and the detection limit is 15 nM. Possible interferences by other ions were studied. The electrode was successfully applied to the determination of total dissolved iron in real coastal waters. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The novel composites based on reduced graphene oxide/methylene blue/gold nanoparticles (rGO/MB/AuNPs) were synthesized by a green and easy method. This synthesis was realized through a one-step green reduction of graphene oxide and chloroauric acid by ascorbic acid, with MB as the assistant reductant and formed AuNPs as the self-catalyst. Except for electroactive substance, MB, which was firmly coated onto the surface of rGO through π-π stacking non-covalent interactions, also serves as the anchor for AuNPs in situ growth due to the electrostatic attraction between positively charged MB and negatively charged chloroauric ions. The characteristics of rGO/MB/AuNPs composites were investigated by various optical and electrical methods. These composites exhibit excellent electrochemical properties and promising prospects for practical application in electrochemical analysis. [ABSTRACT FROM AUTHOR]

In this work, an easy and effective method to synthesize alizarin red S/multi-walled carbon nanotube (ARS/MWCNT) nanocomposites based on the π- π stacking non-covalent interactions between ARS and MWCNTs was introduced. The characters of ARS/MWCNT nanocomposites were investigated by Fourier transformation infrared spectroscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope, and electrochemical techniques. ARS tightly coating on MWCNTs surface makes the nanocomposites good dispersibility in water and excellent electrochemical activity. Because of the combination of the excellent electroactivity of ARS and the unique properties of MWCNTs, ARS/MWCNT nanocomposites-modified glassy carbon electrode exhibits a good response to the reduction of hydrogen peroxide and takes on a promising prospect of the practical application in electrochemical sensors field. [ABSTRACT FROM AUTHOR]

We report on a novel tin-bismuth alloy electrode (SnBiE) for the determination of trace concentrations of zinc ions by square-wave anodic stripping voltammetry without deoxygenation. The SnBiE has the advantages of easy fabrication and low cost, and does not require a pre-treatment (in terms of modification) prior to measurements. A study on the potential window of the electrode revealed a high hydrogen overvoltage though a limited anodic range due to the oxidation of tin. The effects of pH value, accumulation potential, and accumulation time were optimized with respect to the determination of trace zinc(II) at pH 5.0. The response of the SnBiE to zinc(II) ion is linear in the 0.5-25 μM concentration range. The detection limit is 50 nM (after 60 s of accumulation). The SnBiE was applied to the determination of zinc(II) in wines and honeys, and the results were consistent with those of AAS. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Conducting polymer poly(pyrrole) (PPy) doped with Nafion was successfully used as ion-to-electron transducer in the construction of a solid-contact Pb-selective polymeric membrane electrode. The Nafion dopant can effectively increase the capacitance of the conducting polymer and improve the mechanical robustness of the coating. The transducer layer, PPy-Nafion, characterized by cyclic voltammetry and electrochemical impedance spectroscopy, exhibits a sufficiently high bulk (redox) capacitance and fast ion and electron transport process. The new Pb-selective polymeric membrane electrode, based on PPy-Nafion film as solid contact, shows stable Nernstian characteristics in Pb(NO) solution within the concentration range of 1.0 × 10-1.0 × 10 M, and the detection limit is 4.3 × 10 M. The potential stability of the electrode and the influence of the interfacial water layer were also evaluated by chronopotentiometry and potentiometric water layer test, respectively. The results show that the solid-contact Pb-selective electrode, based on PPy-Nafion film as ion-to-electron transducer, can effectively overcome the potential drift and reduce the water layer between the PPy-Nafion transducer layer and the ion-selective membrane. [ABSTRACT FROM AUTHOR]

A Retraction Note to this paper has been published: https://doi.org/10.1007/s11051-021-05228-y [ABSTRACT FROM AUTHOR]

The vertical profiles, contamination levels, and potential ecological risks of mercury and arsenic were studied from the sediment cores of seven typical intertidal zones, including the Liaohe River Estuary, the Jianhe River Estuary, the Dagu River Estuary, Yancheng Shoal, the Dongtan Yangtze River Estuary, Hangzhou Bay, and the Pearl River Estuary. Marine sediment quality standards, the threshold effect level (TEL), and the probable effect level (PEL) were used as guidelines to evaluate sediment quality. In addition, the geo-accumulation index (Igeo) and potential ecological risk index (Eri) were used to assess contamination and potential ecological risks from mercury and arsenic. The results showed that the Pearl River Estuary was moderately polluted by mercury and represented a high potential ecological risk, while other areas were uncontaminated or mildly contaminated with low or moderate potential ecological risks. The Pearl River Estuary was mildly polluted by arsenic and represented a mild potential ecological risk, while other areas were unpolluted and also posed a mild potential ecological risk. [ABSTRACT FROM AUTHOR]

Anodic stripping voltammetric determination of copper ions was accomplished at a glassy carbon disk electrode modified with core-shell microspheres of the gold@manganese dioxide (Au@MnO2) type. These were synthesized via electrochemical deposition. The gold nanoparticles (AuNPs) were electrochemically deposited and employed as an active support material for the growth of MnO2 to yield Au@MnO2 core-shell particles with unique and regular spherical morphology. The microspheres have a diameter of 200-250 nm and scrolled edges like a cactus. Due to the absorption capacity of MnO2 and the electrocatalytic ability of the AuNPs, an excellent anodic signal is obtained for copper ions. Response is linear in the 20 nM to 1 μM copper ion concentration range, with a 4.9 ± 0.2 nM (n = 3) detection limit under optimized conditions. The electrode is stable and excellently reproducible. It was successfully applied to the analysis of copper ions in spiked seawater samples.Gold nanoparticles were employed as a coupling medium for the bridging of MnO2 on a glassy carbon disk electrode to transfer electrons that enhanced electrochemical detection of copper ions. [ABSTRACT FROM AUTHOR]