Variable sediment methane production in response to different source-associated sewer sediment types and hydrological patterns: Role of the sediment microbiome.

Production of methane (CH4), an essential anthropogenic greenhouse gas, from municipal sewer sediment is a problem deserving intensive attention. Based on long-term laboratory batch tests in conjunction with 16 s rRNA gene sequencing and metagenomics, this study provides the first detailed assessment of the variable sediment CH4 production in response to different pollution source-associated sewer sediment types and hydrological patterns, while addressing the role of the sediment microbiome. The high CH4-production capability of sanitary sewer sediment is shaped by enriched biologically active substrate and dominated by acetoclastic methanogenesis (genus Methanosaeta). Moreover, it involves syntrophic interactions among fermentation bacteria, hydrogen-producing acetogens and methanogens. Distinct source-associated microbial species, denitrifying bacteria and sulfate-reducing bacteria occur in storm sewer and illicit discharge-associated (IDA) storm sewer sediments. This reveals their insufficient microbial function capabilities to support efficient methanogenesis. Hydrogenotrophic methanogenesis (genus Methanobacterium) prevails in both these sediments. In this context, storm sewer sediment has an extremely low CH4-production capability, while IDA storm sewer sediment still shows significant carbon emission through a possibly unique mechanism. Hydrological connections promote the sewer sediment biodegradability and CH4-production capability. In contrast, hydrological disconnection facilitates the prevalence of acetoclastic methanogenesis, sulfate-reducing enzymes, denitrification enzymes and the sulfur-utilizing chemolithoautotrophic denitrifier, which drastically decreases CH4 production. Turbulent suspension of sediments results in relative stagnation of methanogenesis. This work bridges the knowledge gap and will help to stimulate and guide the resolution of 'bottom-up' system-scale carbon budgets and GHG sources, as well as the target CH4 abatement interventions.

Variations in CH4 and CO2 productions and emissions driven by pollution sources in municipal sewers: An assessment of the role of dissolved organic matter components and microbiota.

Variations in methane (CH4) and carbon dioxide (CO2) emissions in municipal sewer driven by pollution sources are complex and multifaceted. It is important to investigate the role of dissolved organic matter (DOM) components and microbiota to better understand what and how those variations occurred. For this purpose, this study provides a systematic assessment based on short-term in-sewer conditioned cultivations, in conjunction with a field survey in four typical sewers in Shanghai Megacity. The results are as follows: (1) Sediment plays a main role in driving the sewer carbon emission behavior owing to its strong associations with the utilized substrates and predominant microbes that significantly promoted the gas fluxes (genera Bacteroidete_vadinHA17, Candidatus_competibacter, and Methanospirillum). (2) Aquatic DOM in overlying water is an indispensable factor in promoting total carbon emissions, yet the dominant microbes present there inversely correlated with gas fluxes (genera Methanothermobacter and Bacteroides). (3) The total fluxes of both CH4 and CO2 enhanced by pavement runoff were limited. Its high COD-CH4/CO2 conversion efficiencies can be ascribed to its dominant anthropogenic humic-like components and the emerged aquatic tyrosine-like components. (4) Domestic sewage can significantly enhance the total fluxes because of its high concentration of bioavailable DOM. However, these substrates, which were more suitable for supporting microbial growth, as well as the substrate competition caused by sulfate reduction and the nitrogen cycle (revealed by the dominant functional microbes genera Acinetobacter, Pseudomonas, Dechloromona, and Candidatus_competibacter and their correlations with indicators), seemed to be responsible for the low COD-CH4/CO2 conversion efficiencies of domestic sewage. (5) A field survey indicated the distinct features of carbon emissions of sewer sewage discharged from different catchments. An extreme hydraulic condition in a sewer in the absence of influent showed unexpectedly high levels of CO2, while a small amount of CH4 emissions.

The influence of background music on recognition processes of Chinese characters: an ERP study.

In this paper, we employed RSS (rapid stream stimulation) paradigm to study the recognition processes of Chinese characters in background music. Real Chinese characters (upright or rotated) were used as target stimuli, while pseudo-words were used as background stimuli. Subjects were required to detect real characters while listening to Mozart's Sonata K. 448 and in silence. Both behavioral results and ERP results supported that Mozart's music mainly served as a distracter in the recognition processes of real Chinese characters in the experiment. The modulation of Mozart's music on RP (recognition potential) was different across different orientations of Chinese characters; in particular, the modulation of RP elicited by upright Chinese characters was more significant, suggesting that the music factor and orientation factor interact to affect the RP component. In brief, the simultaneous playing of Mozart's music did not improve subjects' performance in the detection of real Chinese characters.

An ERP study on whether semantic integration exists in processing ecologically unrelated audio-visual information.

In the present study, we used event-related potentials (ERPs) to examine whether semantic integration occurs for ecologically unrelated audio-visual information. Videos with synchronous audio-visual information were used as stimuli, where the auditory stimuli were sine wave sounds with different sound levels, and the visual stimuli were simple geometric figures with different areas. In the experiment, participants were shown an initial display containing a single shape (drawn from a set of 6 shapes) with a fixed size (14cm(2)) simultaneously with a 3500Hz tone of a fixed intensity (80dB). Following a short delay, another shape/tone pair was presented and the relationship between the size of the shape and the intensity of the tone varied across trials: in the V+A- condition, a large shape was paired with a soft tone; in the V+A+ condition, a large shape was paired with a loud tone, and so forth. The ERPs results revealed that N400 effect was elicited under the VA- condition (V+A- and V-A+) as compared to the VA+ condition (V+A+ and V-A-). It was shown that semantic integration would occur when simultaneous, ecologically unrelated auditory and visual stimuli enter the human brain. We considered that this semantic integration was based on semantic constraint of audio-visual information, which might come from the long-term learned association stored in the human brain and short-term experience of incoming information.

An ERP study on whether the P600 can reflect the presence of unexpected phonology.

In this study, we conducted a new approach to determine whether the P600 could reflect the presence of unexpected phonology. In the experiment, the critical Chinese characters in the poems are either original or substituted by homophones or synonyms. The N400 effect is observed only under the homophonic condition. Late positive shifts are revealed under both homophonic and synonymous conditions, but the amplitude under the homophonic condition is smaller than that under the synonymous condition. The observation of the N400 effect under the homophonic condition indicates that semantic processing occurs in Chinese poem comprehension, while the P600 effect elicited under the homophonic condition is a reflection of unfulfilled semantic expectations. The existence of the late positivity under the synonymous condition reveals that P600 can reflect the presence of unexpected phonology. Interestingly, late positivities under the two conditions both consist of two parts. A discussion ensues wherein these two parts of the late positive shift relate, respectively, to monitoring and resolution processes in language comprehension.

Semantic integration of differently asynchronous audio-visual information in videos of real-world events in cognitive processing: an ERP study.

In the real world, some of the auditory and visual information received by the human brain are temporally asynchronous. How is such information integrated in cognitive processing in the brain? In this paper, we aimed to study the semantic integration of differently asynchronous audio-visual information in cognitive processing using ERP (event-related potential) method. Subjects were presented with videos of real world events, in which the auditory and visual information are temporally asynchronous. When the critical action was prior to the sound, sounds incongruous with the preceding critical actions elicited a N400 effect when compared to congruous condition. This result demonstrates that semantic contextual integration indexed by N400 also applies to cognitive processing of multisensory information. In addition, the N400 effect is early in latency when contrasted with other visually induced N400 studies. It is shown that cross modal information is facilitated in time when contrasted with visual information in isolation. When the sound was prior to the critical action, a larger late positive wave was observed under the incongruous condition compared to congruous condition. P600 might represent a reanalysis process, in which the mismatch between the critical action and the preceding sound was evaluated. It is shown that environmental sound may affect the cognitive processing of a visual event.

The processing of phonological, orthographical, and lexical information of Chinese characters in sentence contexts: an ERP study.

In the current work, we aimed to study the processing of phonological, orthographical, and lexical information of Chinese characters in sentence contexts, as well as to provide further evidence for psychological models. In the experiment, we designed sentences with expected, homophonic, orthographically similar, synonymous, and control characters as endings, respectively. The results indicated that P200 might be related to the early extraction of phonological information. Moreover, it might also represent immediate semantic and orthographic lexical access. This suggested that there might be a dual-route in cognitive processing, where the direct access route and the phonologically mediated access route both exist and interact with each other. The increased N400 under the control condition suggested that both phonological and orthographical information would influence semantic integration in Chinese sentence comprehension. The two positive peaks of the late positive shift might represent the semantic monitoring, and orthographical retrieval and reanalysis processing, respectively. Under the orthographically similar condition, orthographical retrieval and reanalysis processing was more difficult in comparison with the other conditions, which suggested that there might be direct access from orthography to semantic representation in cognitive processing. In conclusion, it was shown that the direct access hypothesis or the dual-route hypothesis could better explain cognitive processing in the brain.

Cognitive processing of traffic signs in immersive virtual reality environment: An ERP study.

The virtual reality environment can provide an immersive feeling as in the real word. So, using virtual reality technology to construct realistic experimental scenarios, the mechanism of cognitive processing in the human brain could be better studied. In this paper, we have designed an experiment, where through the presentation of traffic signs with correct or incorrect background colors in a virtual reality traffic environment, and studied the cognitive processing in the human brain using event-related potential (ERP) method. The results showed that whether the background colors of traffic signs were correct or not, the degrees of familiarity to these traffic signs in the human brain were similar, and the degree of contrast between the background colors and foreground colors of traffic signs would influence the degree of difficulty in cognitive processing. The degree of complexity in contents of traffic signs appears related to the cognitive speed in the human brain. In sum, simpler contents and larger contrast between the background colors and foreground colors of traffic signs would make the human brain respond faster.

The interaction between pictures and words: evidence from positivity offset and negativity bias.

In order to study the interaction between pictures and words, we investigated the variations of their actual arousal levels through the observation of the positivity offset and negativity bias under different conditions. We used emotional pictures and emotional Chinese words to construct stimuli under four conditions: (1) only a word was presented (Word Only condition), (2) only a picture was presented (Picture Only condition), (3) a word was presented before a picture (Word Before Picture condition) and (4) a picture was presented before a word (Picture Before Word condition). The picture and word in each target pair under the conditions (3) and (4) were congruous in content and emotion. Significant negativity bias is noticed under the Picture Only and the Word Only conditions. Effects analogous to a positivity offset are observed under the other two conditions. It is suggested that the actual arousal levels of multiple stimuli, such as those presented under the conditions (3) and (4) are different from those of individual pictures and individual words, while the actual arousal levels of individual pictures do not differ significantly from those of individual words. The results indicate that content consistency can lead to a reduction in emotional attention, and also that the influence of pictures on words will differ from the opposite condition.

The influence on cognitive processing from the switches of shooting angles in videos of real-world events: an ERP study.

This work mainly focuses on the influence from switches of shooting angles in videos during the cognitive processing in the human brain. In the experiment we used the videos with switches of shooting angles as materials and compared the ERPs elicited by the switch frames and the non-switch frames in the videos, it was found that when subjects were asked to pay attention to the video contents, the switch frames would trigger P3a-RON waveforms, but no N400 waveform was found in the ERP results. This showed that when subjects were concerned with the video contents, the switches of shooting angles would distract their attention from the video contents, but as long as the semantic meaning of the videos were coherent, the switches of shooting angles would not lead to significant difficulties in semantic comprehension. At the same time, the experimental results also further proved that the P3a and RON generally reflect the processing of task-irrelevant visual stimuli.

The integration processing of the visual and auditory information in videos of real-world events: an ERP study.

In real life, the human brain usually receives information through visual and auditory channels and processes the multisensory information, but studies on the integration processing of the dynamic visual and auditory information are relatively few. In this paper, we have designed an experiment, where through the presentation of common scenario, real-world videos, with matched and mismatched actions (images) and sounds as stimuli, we aimed to study the integration processing of synchronized visual and auditory information in videos of real-world events in the human brain, through the use event-related potentials (ERPs) methods. Experimental results showed that videos of mismatched actions (images) and sounds would elicit a larger P400 as compared to videos of matched actions (images) and sounds. We believe that the P400 waveform might be related to the cognitive integration processing of mismatched multisensory information in the human brain. The results also indicated that synchronized multisensory information would interfere with each other, which would influence the results of the cognitive integration processing.