Search

Microbially mediated iron redox processes are of great significance in the biogeochemical cycles of elements, which are often coupled with soil organic matter (SOM) in the environment. Although the influences of SOM fractions on individual reduction or oxidation processes have been studied extensively, a comprehensive understanding is still lacking. Here, using ferrihydrite

Organic fertilization is a major contributor to the spread of antibiotic resistance genes (ARGs) in the agroecosystem, which substantially increases the risk of ARGs acquisition and their transmission into human food chains. Earthworms are among the most vital soil faunas involved in the link between belowground and aboveground, and silicon is beneficial for soil health and plant stress resistance. This study aims to explore the effect of different amendment strategies (earthworm and/or silicon) and the related influencing factors on the alleviation of ARGs using high-throughput qPCR. The results showed that the application of earthworms and silicon fertilizers reduced the absolute abundance of ARGs in the rhizosphere soils, either singly or in combination. According to the structural equation model and random forest analysis, mobile genetic elements are the major factors enhancing ARGs transfers and the treatment affects ARGs in direct or indirect ways. Our results highlight the role of "rhizosphere effect" in alleviating antibiotic resistance and suggest that silicon fertilizers, together with the earthworms, can be considered as a sustainable and natural solution to mitigate high-risk ARGs spread in the soil-plant systems. Our findings provide guidance in formulating strategies for halting the spread of ARGs in the agroecosystem.

The intertidal zone, due to its location in the transition zone of terrestrial and marine ecosystems, is seriously disturbed by anthropogenic activities such as fuel combustion and industrial production, causing significant increase in dissolved organic matter (DOM). However, the distribution and properties of DOM in intertidal sediments at the large scale and their correlations with local socio-economic indicators remain unclear. In this study, we collected sediment samples from 13 intertidal zones across 11 coastal provinces in China and analyzed optical properties and compositions of sedimentary DOM. The results showed that the physico-chemical properties of sediment, such as pH and texture, affected the content of organic matter, thereby influencing the concentration of sedimentary DOM indirectly. The contents of fulvic acid- and protein-like components were relatively higher than humic acid-like component at all sampling sites. Moreover, urbanization could lead to the release of aromatic and humified organic matters into intertidal zones. Unlike coal, oil consumption exhibited positive correlation with SUVA

Ruixia Han,1,2 Jian Xu1– 3 1School of Media and Communication, Shanghai Jiao Tong University, Shanghai, 200240, People’s Republic of China; 2Institute of Cultural Innovation and Youth Development, Shanghai Jiao Tong University, Shanghai, 200240, People’s Republic of China; 3Institute for Urban Governance, Shanghai Jiao Tong University, Shanghai, 200052, People’s Republic of ChinaCorrespondence: Ruixia Han; Jian Xu, School of Media and Communication, Shanghai Jiao Tong University, Shanghai, 200240, People’s Republic of China, Tel/Fax +86 21-34202854, Email annahan08@sjtu.edu.cn; xujian@sjtu.edu.cnIntroduction: Based on the cognitive-affective model, this paper examines how social media affects the public cognitive and affective factors, further influence their attitudes towards COVID-19 governance policy.Methods: Through an online survey, we measured individual COVID-19 policy attitude, social media use and other related factors of 1222 respondents from 12 countries, and based on this, we carried out regression and mediation analysis on the data to obtain the research results.Results: From the perspective of cognitive factors, the public perception of the severity of the COVID-19 itself does not significantly affect their attitudes towards governance policy. On the contrary, the evaluation on government governance performance, risks and governance anticipations have more significant impacts. Among the affective factors, personal anxiety and patriotism significantly affect the formation of public attitudes, personal anxiety is positively correlated, and patriotism is negatively correlated. It is important to note that nationalism has no significant influence on public attitudes to COVID-19 policy on a global scale.Conclusion: (1) Social media influences the public COVID-19 policy attitudes through their moderating effect on affective and cognitive factors. (2) The impact of social media on affective pathways is more significant than that on cognitive pathways. (3) The positive moderating effect of social media on patriotism obscures the tendency of strict governance of COVID-19 caused by aggravating people’s anxiety.Keywords: Covid-19, public attitude, social media, cognition, affection, patriotism

International metropolises are key sites of outbreaks of COVID-19 cases. Global public evaluation of the pandemic in international cities is affected by many factors. This study examines how media exposure affects this evaluation and how media trust and media bias perception moderate the relationship between them. Based on an online survey of the evaluation of 13 international cities’ pandemic performances by 1171 citizens from 11 countries, this study conducted a multi-level stepwise regression analysis and discovered that: (1) different forms of media affect global citizens’ perceptions of international metropolis COVID-19 pandemic performance differently; and the role of traditional paper media, including newspapers and magazines, is of little significance in comparison to electronic media. (2) Among electronic media, TV and broadcasting have the greatest impact, followed by social media and the Internet. (3) Media trust and media bias perception affect people’s evaluations of international urban pandemics, but our survey reveals that they only function with regard to social media.

In peri-urban critical zones, soil ecosystems are highly affected by increasing urbanization, causing probably an intense interaction between dissolved organic matter (DOM) and heavy metals in soil. Such interaction is critical for understanding the biogeochemical cycles of both organic matter and heavy metals in these zones. However, limited research has reported the correlative distribution of DOM and heavy metals at high seasonal and spatial resolutions in peri-urban critical zones. In this study, 160 soil samples were collected from the farmland and forestland of Zhangxi watershed, in Ningbo, eastern China during spring, summer, fall and winter four seasons. UV-visible absorption and fluorescent spectroscopy were used to explore the optical characteristics of DOM. The results indicated a mixture of exogenous and autogenous sources of DOM in the Zhangxi watershed, while DOM in farmland exhibited a higher degree of aromaticity and humification than that in forestland. Fluorescent results showed that humic acid-like, fulvic acid-like and microbial-derived humic-like fractions were mostly affected by seasons. The distribution of heavy metals was affected mainly by land-use changes and seasons. Correlation analysis between heavy metals and DOM characteristics and components suggested that aromatic and humic substances were more favorable in binding with EDTA extractable Ni, Cu, Zn and Cd. The bioavailable Cd and Pb decreased due to binding with humic fractions, indicating that DOM had great effects on the heavy metal bioavailability. Overall, these findings provide an insight into the correlative distributions of DOM and heavy metals in peri-urban areas, thereby highlighting their biogeochemical cycling in the soil environment.

The activation of norm perception can promote pro-environmental behavior. How does media, as important variables in activating norm perception, affect pro-environmental behavior? Through an online survey of 550 randomly selected Chinese citizens, this study examines the roles of traditional media and social media in influencing the relationship between norm perception and pro-environmental behavior. Based on multi-level regression analysis of data, this study found that (1) compared with traditional media, social media play a more significant role in moderating the relationship between norm perception and pro-environmental behavior, (2) the promotion of the perception of injunctive norms by traditional media has a negative relationship with pro-environmental behaviors, (3) the activation of subjective norm perception by social media will promote pro-environmental behaviors. According to this research, in the current media environment, we should carefully release pro-environmental information on social media and encourage relevant discussions, and appropriately reduce environment-relevant injunctive normative information on traditional media. The study also discusses the role of media in regulating norm perception and pro-environmental behavior in different cultural contexts.

In peri-urban critical zones, soil ecosystems are highly affected by increasing urbanization, causing probably an intense interaction between dissolved organic matter (DOM) and heavy metals in soil. Such interaction is critical for understanding the biogeochemical cycles of both organic matter and heavy metals in these zones. However, limited research has reported the correlative distribution of DOM and heavy metals at high seasonal and spatial resolutions in peri-urban critical zones. In this study, 160 soil samples were collected from the farmland and forestland of Zhangxi watershed, in Ningbo, eastern China during spring, summer, fall and winter four seasons. UV-visible absorption and fluorescent spectroscopy were used to explore the optical characteristics of DOM. The results indicated a mixture of exogenous and autogenous sources of DOM in the Zhangxi watershed, while DOM in farmland exhibited a higher degree of aromaticity and humification than that in forestland. Fluorescent results showed that humic acid-like, fulvic acid-like and microbial-derived humic-like fractions were mostly affected by seasons. The distribution of heavy metals was affected mainly by land-use changes and seasons. Correlation analysis between heavy metals and DOM characteristics and components suggested that aromatic and humic substances were more favorable in binding with EDTA extractable Ni, Cu, Zn and Cd. The bioavailable Cd and Pb decreased due to binding with humic fractions, indicating its great effects on the bioavailability of Cd and Pb. Overall, these findings provide an insight into the correlative distributions of DOM and heavy metals in peri-urban areas, thereby highlighting their biogeochemical cycling in the soil environment.

Humic substances (HSs) are collections of diverse organic compounds with broad redox capacities, which directly or indirectly affect the biogeochemical behaviors and fates of almost all the pollutants in the environment. The present study investigates the relationships between the molecular characteristics of HSs and their reducing capacities or electron-donating capacities (EDCs) by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), total phenolic assay, and mediated electrochemical oxidation analysis. For decreasing the molecular heterogeneity of bulk HSs, HSs were first separated into three fractions according to their polarities. The results demonstrated that compounds in HS fractions with moderate polarity possessed a high content of total phenols and consistently had high EDCs. A strong linear correlation (R2 = 0.97) existed between EDCs and the total phenolic content, which confirmed that phenols contributed to the EDCs of HSs. Further anal...

Due to its complex composition and structure, many of the properties of natural organic matter (NOM) are poorly understood. In this study, the oxidization-induced chemiluminescence (OCL) of NOM was investigated, and a flow-injection OCL method was developed using alkaline persulfate-H

The reduction of ferric iron (Fe(III)) to ferrous iron (Fe(II)) by dissimilatory iron-reducing bacteria is widespread in anaerobic environments. The oxidation of Fe(II) in aerobic environments has been found to produce hydroxyl radicals (

China is facing tremendous pressure to improve the environment. How to promote pro-environmental behaviors at the individual level is an important research topic. This study examines the relationship between social media usage, place attachment, and pro-environmental behavior based on a survey of 550 Chinese citizens. The results show that: (1) Place attachment and social media usage for environmental information acquisition have positive correlations with pro-environmental behaviors, (2) social media usage for environmental information acquisition moderates the relationship between place attachment and pro-environmental behaviors. Our survey also finds that social media play a more important role than traditional media in influencing pro-environmental behaviors. Our findings indicate that social media is changing the traditional relationship between place attachment and pro-environmental behavior. We should pay more attention to this positive role of social media and encourage citizens&rsquo, pro-environmental behavior.

Manganese (Mn) oxides are ubiquitous in the environment and have strong reactivity to induce the transformation of various contaminants. However, whether reactive oxygen species contribute to their surface reactivity remains unclear. Here, sustainable production of superoxide radicals (O2•-) by various MnO2 polymorphs in the dark was quantified and the mechanisms involved were explored. The results confirm that O2•- was produced through one-electron transfer from surface Mn(III) to adsorbed O2. In contrast, no H2O2 was detected due to its decomposition by Mn oxides to form O2•- and Mn(III), leading to the sustained production of O2•- on Mn oxide surfaces. In addition, the production of O2•- was found to make a clear contribution (4 - 28%) to the transformation of a series of halophenols by MnO2, suggesting that the O2•--mediated surface reaction is an important supplement to the direct electron-transfer mechanism in the reactivity of Mn oxides. These findings advance our understanding of the surface reactivity of Mn oxides and also reveal an important but hitherto unrecognized abiotic source of O2•- in the natural environment.

Microbial dissimilatory iron reduction and aerobic oxidation affect the biogeochemical cycles of many elements. Although the processes have been widely studied, the underlying mechanisms, and especially how the surface structures of iron oxides affect these redox processes, are poorly understood. Therefore, {001} facet-dominated hematite nanoplates (HNP) and {100} facet-dominated hematite nanorods (HNR) were used to explore the effects of surface structure on the microbial dissimilatory iron reduction and aerobic oxidation processes. During the reduction stage, the production of total Fe(II) normalized by specific surface area (SSA) was higher for HNP than HNR due to steric effects and the ligand-bound conformation of the connection between iron on different exposed facets and electron donors from microorganisms. However, during the aerobic oxidation stage, both the SSA- and Fe(II)-normalized reactive oxygen species (ROS), including hydrogen peroxide (H2O2) and hydroxyl radical (•OH), were higher for HNR than HNP. Theoretical calculation results showed that the {100} facets exhibited a lower activation energy barrier for oxygen reduction reaction than {001} facets, supporting the experimental observation that {100} facet-dominated HNR had a higher ROS production efficiency than {001} facet-dominated HNP. These results indicated that surface characteristics not only mediated the microbial reduction of Fe(III) but also affected the aerobic oxidation of microbially reduced Fe(II). Accessibility of electron donors to surface iron atom determined the reduction of Fe(III), and activation energy barrier for oxygen reduction by surface Fe(II) dominated the ROS production during the redox processes. This study advances our understanding of the mechanisms through which ROS are produced by iron (oxyhydr)oxides during microbial dissimilatory iron reduction and aerobic oxidation processes.

The advance of information and communication technologies (ICTs) has fundamentally changed the way people communicate and interact with each other, and the rise of the Internet profoundly affects political participation. In applying the latest Asian Barometer surveys, we discovered Internet-driven divergent effects on political participation, suggesting rising Internet usage is simultaneously associated with decreasing electoral and increasing activist participation. Further analysis revealed that the divergent effects can be explained by severe frustration with the political system and economic conditions. When considering state polity characteristics, we found that the Internet-driven divergent effects in a democratic context refer to a coincidence of two Internet-related effects that decrease electoral and increase activist participation; in an authoritarian context, they indicate a correlation between greater Internet usage and a preference for activist over electoral participation.

Interactions between dissolved organic matter (DOM) and iron oxyhydroxides have important environmental and geochemical implications. The present study employed two hematite nanocrystals to investigate the adsorption and molecular fractionation of two typical humic substances (HSs) using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). Hematite with a predominant exposure of {100} facets induced more pronounced adsorption and molecular fractionation of HSs than {001} facets, indicating that the interfacial adsorptive fractionation process of HSs was mediated by exposed facets of hematite. Further exploration of the surface OH groups of the two hematite nanocrystals confirms that the facet-mediated molecular fractionation of HSs was attributable to the abundance of singly iron-atom coordinated -OH sites on the hematite surfaces. Molecules with a high oxidation state and high aromaticity such as oxidized black carbon, polyphenol-like, and tannic-like compounds preferentially formed ligand-exchange complexes with singly coordinated -OH groups on the hematite surfaces, inducing the selective binding and molecular fractionation of HSs at the mineral-water interface. These results demonstrate that singly iron-atom coordinated -OH sites determine DOM adsorption and mediate molecular fractionation on hematite surfaces, and this contributes substantially to our understanding of the molecular mechanisms of iron oxyhydroxide-mediated molecular exchange of DOM in soils and/or sediments.

A novel biosensor was fabricated based on hemoglobin (Hb) immobilized onto cuprous sulfide (Cu2S) nanorods/nafion nanocomposite film for the detection of polyphenols in the presence of hydrogen peroxide (H2O2). The nanostructured inorganic–organic hybrid material formed by Cu2S nanorods and nafion provided a biocompatible microenvironment for Hb and increased the sensitivity for polyphenols detection. The modified electrodes were characterized by electrochemical impedance spectroscopy and linear sweep voltammetry. Parameters such as pH, H2O2 concentration, and the applied potential were optimized. Under optimum conditions, the biosensor gave linear response ranges of 7.0–110, 0.6–10, and 8–100 μM for catechol, hydroquinone, and resorcin, with the detection limits of 0.5, 0.03, and 0.6 μM (S/N = 3), respectively. The developed biosensor exhibited a short response time within only 8 s with good stability and reproducibility. Such a novel biosensor showed great promise for rapid, simple analysis of polyphenols contents in real samples.

A sensitive electrochemical method for the detection of avian influenza virus (AIV) H5N1 gene sequence using a DNA aptamer immobilized onto a hybrid nanomaterial-modified electrode was developed. To enhance the selectivity and sensitivity, the modified electrode was assembled with multi-wall carbon nanotubes (MWNT), polypyrrole nanowires (PPNWs) and gold nanoparticles (GNPs). This electrode offered a porous structure with a large effective surface area, highly electrocatalytic activities and electronic conductivity. Therefore, the amount of DNA aptamer immobilized onto the electrode was increased while the accessibility of the detection target was maintained. The biosensor is based on the hybridization and preferred orientation of a DNA aptamer immobilized onto a modified electrode surface with its target (H5N1 specific sequence) present in solution. It is selective for the H5N1 specific sequence, and the signal of the indicator was approximately linear to log(concentration) of the H5N1 specific sequence from 5.0 × 10−12 to 1.0 × 10−9 M (R = 0.9863) with a detection limit of 4.3 × 10−13 M. These studies showed that the new hybrid nanomaterial (MWNT/PPNWs/GNPs) and the DNA aptamer could be used to fabricate an electrochemical biosensor for gene sequence detection. Furthermore, this design strategy is expected to have extensive applications in other biosensors.

A new electrochemical biosensor for directly detecting DNA damage induced by acrylamide (AA) and its metabolite was presented in this work. The graphene-ionic liquid-Nafion modified pyrolytic graphite electrode (PGE) was prepared, and then horseradish peroxidase (HRP) and natural double-stranded DNA were alternately assembled on the modified electrode by the layer-by-layer method. The PGE/graphene-ionic liquid-Nafion and the construction of the (HRP/DNA) n film were characterized by electrochemical impedance spectroscopy. With the guanine signal in DNA as an indicator, the damage of DNA was detected by differential pulse voltammetry after PGE/graphene-ionic liquid-Nafion/(HRP/DNA) n was incubated in AA solution or AA + H 2 O 2 solution at 37 °C. This method provides a new model to mimic and directly detect DNA damage induced by chemical pollutants and their metabolites in vitro. The results indicated that, in the presence of H 2 O 2 , HRP was activated and catalyzed the transformation of AA to glycidamide, which could form DNA adducts and induce more serious damage of DNA than AA. In order to further verify these results, UV–vis spectrophotometry was also used to investigate DNA damage induced by AA and its metabolites in solution and the similar results were obtained.

A novel bio-composite film which contains multi-walled carbon nanotube (MWNT)-chitosan (Chit)/poly(amidoamine) (PAMAM) nanocomposite along with the incorporation of DNA modified Au electrode as a biosensor for determination of dopamine(DA) and uric acid (UA) under coexistence of ascorbic acid (AA) was fabricated by layer-by-layer modification. Electrochemical impedance spectroscopy (EIS) and Cyclic Voltametry (CV) were used to characterize the electrochemical properties of the modified electrodes. The biosensor was applied to detect DA and UA in the presence of AA. It not only exhibited strong catalytic activity toward the oxidation of DA and UA but also separated the originally overlapped signals of UA, DA and AA oxidation at the bare electrode into three well-defined peaks. The peak separation between AA and DA, AA and UA was 179 mV and 288 mV, respectively. In the presence of 1.0 mM AA, two linear relationships were obtained for DA over the concentration range from 0.2 to 10 μM (R = 0.9984) and 10–100 μM (R = 0.9957) with a detection limit of 0.03 μM (s/n = 3). The anodic peak current of UA was also a linear relationship in the concentration range 0.5–100 μM (R = 0.9971) with a detection limit of 0.07 μΜ. Moreover, the modified electrode surface has very good reproducibility and stability.

A tyrosinase (Tyr) biosensor has been constructed by immobilizing tyrosinase on the surface of Mg–Al–CO3 hydrotalcite-like compound film (HTLc) modified glassy carbon electrode (GCE) for the determination of polyphenols. The negatively charged tyrosinase was adsorbed firmly on the surface of a positively charged HTLc/GCE by electrostatic interactions and retained its activity to a great degree. The modified electrode was characterized by cyclic voltammetry and AC impedance spectra. Polyphenols were determined by a direct reduction of biocatalytically generated quinone species. The different parameters, including pH, temperature, and enzyme loading were investigated and optimized. Under the optimum conditions, Tyr/HTLc electrode gave a linear response range of 3–300, 0.888–444, and 0.066–396 μM with a detection limit (S/N = 3) of 0.1, 0.05, and 0.003 μM for catechol, caffeic acid, and quercetin, respectively. In addition, the repeatability and stability of the enzyme electrode were estimated. Total polyphenol contents of real samples were also determined to study the potential applicability of the Tyr/HTLc/GCE biosensor.

Catalytic removal of bisphenol A from aqueous solution with hemoglobin immobilized on amino-modified magnetic nanoparticles as an enzyme catalyst was reported. The amino-modified magnetite nanoparticles were firstly prepared by the coprecipitation of Fe2+ and Fe3+ with NH3·H2O and then modified by 3-aminopropyltriethoxysilane. The immobilization process was optimized by examining enzyme concentration, glutaraldehyde concentration, cross-link time, and immobilization time. The optimum conditions for the removal of bisphenol A with immobilized hemoglobin were also investigated. Under the optimality conditions, the removal efficiency of bisphenol A was about 80.3%. The immobilization had a beneficial effect on the stability of hemoglobin and conversions of bisphenol A. According to the proposed breakdown pathway and the intermediates, the enzyme-catalytic removal of bisphenol A by the immobilized hemoglobin is considered to be an effective method.

A novel electrochemical method of detecting DNA hybridization is presented based on the change in flexibility between the single and double stranded DNA. A recognition surface based on gold nanoparticles (GNPs) is firstly modified via mixing self-assembled monolayer of thiolated probe DNA and 1,6-hexanedithiol. The hybridization and electrochemical detection are performed on the surface of probe-modified GNPs and electrode, respectively. Here in our method the charge transfer resistance ( R ct ) signal is enhanced by blocking the surface of electrode with DNA covered GNPs. The GNPs will be able to adsorb on the gold electrode when covered with flexible single stranded DNA (ssDNA). On the contrary, it will be repelled from the electrode, when covered with stiff double stranded DNA (dsDNA). Therefore, different R ct signals are observed before and after hybridization. The hybridization events are monitored by electrochemical impedance spectroscopy (EIS) measurement based on the R ct signals without any external labels. This method provides an alternative route for expanding the range of detection methods available for DNA hybridization.

Environmental contextNotwithstanding the environmental and geochemical significance of soil dissolved organic matter (DOM), its molecular components are still not well characterised. This study investigates chemical similarities and differences between two widely used forms of soil DOM: water-extractable organic matter and fulvic acids. The findings will guide appropriate extraction and purification protocols in future studies related to soil DOM. AbstractDissolved organic matter (DOM) is the most active fraction of soil organic matter (SOM), which has both environmental and geochemical importance. However, the extraction of DOM from soils is still ambiguous. Instead, operational concepts, such as fulvic acid (FA) and water-extractable organic matter (WEOM), are widely used in practice. In this study, the molecular components of FA and WEOM extracted from two standard soils were investigated by using electrospray ionisation coupled with Fourier-transform ion cyclotron resonance mass spectrometry and proton nuclear magnetic resonance (1H NMR) spectroscopy to clarify the molecular similarities and differences between them. The results revealed that WEOM and FA shared many of the same molecules, which accounted for 64% and 82% of the total numbers of molecules for WEOM and FA respectively. However, WEOM displayed higher chemical and molecular diversities than FA. Detailed analysis revealed that the extraction and desalination procedure of FA led to the loss of lignin, protein and carbohydrate compounds, but induced preferential release of some tannin-like molecules from the aggregate- or organic mineral-associated SOM. Based on the results of the present study, water extraction combined with desalination through a functionalised styrene divinylbenzene polymer-based solid phase extraction is more reliable to retain the molecular diversity of soil DOM.

An electrochemical method for the detection of DNA hybridization using a novel electroactive, cationic, and water-soluble branched polyethyleneimine (BPEI)–cobalt(III)–phenanthroline(phen) polymeric indicator and single-stranded neutral peptide nucleic acid (PNA) probe on the Au electrode was developed. The indicator possesses some free amine groups, as well as cationic cobalt complexes in the polymer chain. It does not bind to neutral PNA capture probe alone. However, the indicator strongly interacts with the negatively charged backbone of the complementary oligonucleotide bound to the PNA probe through electrostatic interactions. The coordination spherical moieties also interact with the probe by embedding into the double-helix structure of PNA–DNA. These two interactions enable transduction of hybridization, producing a clear electrical signal in differential pulse voltammetry (DPV). The correlation against non-complementary DNA, three-base and one-base mismatch DNA was sharp, and the signal of indicator for the target DNA demonstrated a linear relationship within the concentration range of 5.0 × 10−9 to 2.5 × 10−7 M (R = 0.9940) with a detection limit of 5.6 × 10−10 M. These studies showed that the novel polymeric indicator and single-stranded PNA probe could be used to fabricate an electrochemical biosensor for DNA detection. This technique can provide an alternative route for expanding the range of detection methods available for DNA hybridization.

This paper presents a novel electroenzymatic method for the treatment of bisphenol A (BPA) in a membraneless electrochemical reactor. The electrochemical reactor was arranged with a stainless steel and an enzymatic film as anode and cathode, respectively. The enzymatic film was formed by immobilizing hemoglobin (Hb) on carbon fiber. In the membraneless electrochemical reactor, hydrogen peroxide (H(2)O(2)) was generated in situ in cathode and BPA was oxidated and removed by the combining Hb with H(2)O(2). The experimental conditions for electrogeneration of H(2)O(2) and electroremoval of BPA were optimized. Experimental results showed that in supplied voltage 2.4 V, pH 5.0 and oxygen flow rate 25 mL/min, the electrogeneration of H(2)O(2) and the electroenzymatic removal of BPA were highest. Under optimal operation conditions, the removal efficiency of BPA reached 50.7% in 120 min and then kept constant when further prolonging the period of reaction. Compared with electrochemical and biochemical methods, the removal of BPA through electroenzymatic method was comparatively favorable.

A glassy carbon electrode was modified with dsDNA and a nanocomposite composed of multi-walled carbon nanotubes and chitosan (MWNT-chit). The electrode was applied to the electrochemical detection of DNA damage as induced by in situ generated bisphenol A (BPA) radicals through electro-oxidation. The modified electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that MWNT-chit nanocomposite represents a viable platform for the immobilization of DNA that effectively promotes electron transfer between DNA and the electrode. The mode of interaction between DNA and BPA was investigated by differential pulse voltammetry and UV-vis spectrophotometry, indicating that the dominant interaction is intercalation. In order to explore the mechanism of damage caused by BPA radicals, the electro-oxidation of BPA at the modified glass electrode was investigated. Based on the signal for guanine without any other external indicator, DNA damage was investigated through the electro-oxidation of BPA.

A glassy carbon electrode was modified with a composite made from gold nanoparticles and silk fibroin whose surface was further modified with amino-terminated G4 poly(amidoamine) dendrimer. This electrode shows distinct electrochemical response to bisphenol A (BPA). Electrochemical impedance spectroscopy was used to characterize the surface. The electrode displayed improved adsorption capacity and an increased response to BPA, compared to a surface without modification. Under the optimal detection conditions, the respeonse is linear in the concentration range from 1 nM to 1.3 μM, the correlation coefficient is 0.9991, and the detection limit is 0.5 nM (at an S/N of 3). The method was applied to the determination of BPA in water samples, and the recovery was in the range from 97% to 105%.

This study presents a detailed kinetic investigation on the uptake, acropetal translocation and transformation of BDE-47, 6-OH-BDE-47 and 6-MeO-BDE-47 in maize (Zea mays L.) by hydroponic exposure. Root uptake followed the order: BDE-47 > 6-MeO-BDE-47 > 6-OH-BDE-47, while 6-OH-BDE-47 was the most prone to acropetal translocation. Debromination rates of BDE-47 were 1.31 and 1.46 times greater than the hydroxylation and methoxylation rates, respectively. Transformation from BDE-47 to lower brominated OH/MeO-PBDEs occurred mainly through debromination first followed by hydroxylation or methoxylation. There was no transformation from 6-OH-BDE-47 or 6-MeO-BDE-47 to PBDEs. Methylation rate of 6-OH-BDE-47 was twice as high as that of 6-MeO-BDE-47 hydroxylation, indicating methylation of 6-OH-BDE-47 was easier and more rapid than hydroxylation of 6-MeO-BDE-47. Debromination and isomerization were potential metabolic pathways for 6-OH-BDE-47 and 6-MeO-BDE-47 in maize. This study provides important information for better understanding the mechanism on plant uptake and transformation of PBDEs.

Microblogging is a passive broadcast medium in the form of blogging. By publishing message independently and focusing on others' message, people build new interpersonal social network. In Granovetter's framework of strong tie and weak tie, different distances of relationship in reality would influence the efficiency of individual action. The paper analyzes the relationship among microbloggers by four dimensions including a linear combination of the amount of time, the emotional intensity, the intimacy, and the reciprocal. Furthermore the paper proposes three hypotheses: 1) Personal social network would get greatly extended by microblogging; 2) Personal strong ties in microblogging are not identical with his/her strong ties in reality. 3) Strong ties in microblogging would be beneficial to satisfy personal emotion need and information need. By doing case study on 2 microbloggers, the paper tests the three hypotheses and gives a short comment on the influence of microblogging on personal social network.

Electro-enzymatic processes, which are enzyme catalysis combined with electrochemical reactions, have been used in the degradation of many environment pollutants. For some pollutants, the catalytic mechanisms of the electrochemical-enzyme reaction are still poorly understood. In this paper, the degradation of chlorpyrifos by a combination of immobilized hemoglobin and in situ generated hydrogen peroxide is reported for the first time. Hemoglobin was immobilized on graphite felts to catalyze the removal of chlorpyrifos in an electrochemical-enzyme system. Under the optimal conditions, more than 98% of the chlorpyrifos was degraded. Furthermore, the degradation products of chlorpyrifos were also studied and identified using liquid chromatography-mass spectrometry analysis. The results suggest a possible degradation mechanism for chlorpyrifos with low power and high efficiency, reveal the feasibility of hemoglobin as a substitute for some expensive natural enzymes, and demonstrate the application of an electro-enzymatic process in the treatment of organophosphorus compounds in wastewater.

This essay examines the influence of microblogging on personal public participation by articulating microblog with media event. Based on analyzing of microblogging characters, the paper thinks web-identity connected with roles in microblog tenders to evoke media event which is different from media event evoked by mainstream media. Further, by articulating hegemony of Hall, ritual view of communication of James Carey with media event evoked by microblogger, the paper insists microblogging would enhance personal public participation. At the last, the essay analyzes the possible danger that microblogging would face.