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The microbial manganese removal process is believed to consist of the catalytic oxidation of Mn(II) by manganese oxidase. In this study, the multicopper oxidase CopA was purified and exhibited high manganese oxidation activity in vitro, and it was found that Cu(II) can significantly enhance its manganese oxidation activity. Gene site-directed mutagenesis was used to mutate four conserved copper binding sites of CopA to obtain four mutant strains. The manganese removal efficiencies of the four strains were determined, and it was found that H120 is the catalytically active site of CopA. The loss of Cu(II) and the mutation of the conserved copper binding site H120 resulted in the loss of ethoxyformyl and quinone modifications, a reduction in the number of modifications, and a change in the position of modifications, eventually causing a decrease in protein activity from 85.87% to 70.1%. These results reveal that Cu(II) and H120 play an indispensable role in manganese oxidation by the multicopper oxidase CopA. X-ray photoelectron spectroscopy (XPS) analysis indicates that biogenic manganese oxides produced by strains and by CopA were both composed of MnO2 and Mn3O4 and that the average valence of Mn was 3.2.

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Sentiment analysis is one of the fields of affective computing, which detects and evaluates people's psychological states and sentiments through text analysis. It is an important application of text mining technology and is widely used to analyze comments. Bullet screen videos have become a popular way for people to interact and communicate while watching online videos. Existing studies have focused on the form, content, and function of bullet screen comments, but few have examined bullet screen comments using natural language processing. Bullet screen comments are short text messages of different lengths and ambiguous emotional information, which makes it extremely challenging in natural language processing. Hence, it is important to understand how we can use the characteristics of bullet screen comments and sentiment analysis to understand the sentiments expressed and trends in bullet screen comments. This study poses the following research question: how can one analyze the sentiments ex-pressed in bullet screen comments accurately and effectively? This study mainly proposes an ERNIE-BiLSTM approach for sentiment analysis on bullet screen comments, which provides effective and innovative thinking for the sentiment analysis of bullet screen comments. The experimental results show that the ERNIE-BiLSTM approach has a higher accuracy rate, precision rate, recall rate, and F1-score than other methods.

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Excessive intake of manganese seriously affects human health. Manganese oxidizing bacteria can efficiently remove manganese, among which manganese oxidase plays a decisive role. Multicopper oxidase, one of the manganese oxidases, has 4 copper binding sites, among them, T1Cu coordinates with two histidine, one cysteine and one axial residue, mainly transferring electrons from the substrate to T2Cu and T3Cu. Here, we conducted site-directed mutagenesis on T1Cu coordinating 495 amino acid site from cysteine to aspartic acid, histidine and methionine in multicopper oxidase CopA from Brevibacillus panacihumi MK-8, through the enzyme kinetics and structure models, finding that the enzyme catalytic efficiency (kcat/Km) of the mutated C495H with Mn2+ and ABTS reached 9.03 min-1 mM-1 and 8863 s-1 mM-1, 1.47 times and 1.67 times that of CopA. And it was found strain Rosetta-pET-copAC495H could remove 91.67% manganese after 7-day culture, which was 11.65% higher than the original strain. To sum up, these results provide a vision for the future application of protein engineering in biological manganese removal.

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Manganese contamination of groundwater exists worldwide. Manganese removal is primarily performed through catalytic oxidation by manganese-oxidizing bacteria. In this study, we identified a new manganese(II) oxidase (CopA) from Brevibacillus panacihumi MK-8. The copA gene was cloned and expressed in Escherichia coli strain BL21(DE3), and the recombinant strain BL21-pET-copA was able to remove 85.87% of Mn(II) from LB medium containing 1 mM Mn(II) after seven days. The optimum Mn(II) oxidase CopA activity was obtained at 37 °C in 10 mM HEPES buffer (pH 8.0) containing 0.4 mM CuCl2. Purified CopA removed 51.98% of manganese(II) under the optimal conditions. The copA gene-deleted strain (MK-8-ΔcopA) barely oxidized manganese, further demonstrating that the copA gene is the manganese oxidase gene. Biogenic Mn oxides were analyzed by scanning electron microscopy and X-ray diffraction. Thus, we suggest that the recombinant BL21-pET-copA strain and oxidase CopA have the potential to be used in biological manganese removal technology.

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Manganese contamination has become a serious environmental problem in the world and bacterial removal plays an important role in global cycling of manganese. In this study, microorganism distribution within samples from a manganese mine was analyzed with PCR-DGGE technology. The results suggested that Manganese oxidizing bacteria (such as Bacillus, Hyphomicrobiaceae and Erythrobacter) were dominant in the soil. In addition, a Lysinibacillus sp. Isolate, strain MK-1, revealed robust growth at high Mn(II) concentrations up to 1 mM. At that concentration, 55.94% of added Mn(II) was oxidized and 36.23% of the Mn(II) was adsorbed by MK-1(total manganese removal reached 94.67%) after 7 days of culturing. By measuring its metabolic process, the great role of biological adsorption was found. Additionally, the spectroscopic result demonstrated that Mn(III) was an intermediate during the biological oxidation process. These findings increase the knowledge of biological manganese removal mechanisms and show some potentials to the operation of manganese treatment.

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Polyaniline/active carbon (PANI) and nanometer-sized TiO2 (n-TiO2) were prepared by oxidation and sol-gel methods, respectively, and were then used as a zymophore to modify a glassy carbon electrode (GCE) and a GOx/n-TiO2/PANI/GCE sensor with a synergistic effect was established. A series of performance evaluations for the modified material and sensor was studied in detail through cyclic voltammetry (CV) and a chronoamperometry (CA) method. The results showed that the sensor had a good response to glucose and that the electron of the GOx molecule was transferred directly onto the sensor, and a linear relationship between the GOx redox peak current and the sweep speed was found. The apparent transmission speed constant, k, for dissimilar electrode charges was 1.35s(-1), 95% of the maximum steady current for the GOx/n-TiO2/PANI/GCE sensor could be reached in 10s, the linear range of the detected glucose concentration was from 0.02 mM to 6.0mM, the sensitivity was 6.31 µA mM(-1)cm(-2), and the limit of detection was 18 µM. The sensor had good selectivity and stability and could be maintained at 82% of the initial activity for 30 days.

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In order to investigate biological properties of the dominant strain from the biological activated carbon (BAC) filter column, a novel, dominant iron-and-manganese removal strain, FM-2, was screened from BAC mature biological membrane. By phylogenetic analysis based on 16S rDNA sequence comparison, FM-2 was identified to be Citrobacter freundii. The experimental results indicated that Citrobacter sp. FM-2 could remove 83.6% Fe (II) and 64.9% Mn (II) after four days. Inoculum greatly influenced the iron-manganese removal performances. The appropriate inoculum concentration was 5%. The initial concentrations of Fe (II) and Mn (II) had little negative influence on its removal performance. When Fe (II) and Mn (II) concentrations were 32.9~85.7 and 25.7~46.7 mg/L, respectively, the removal of Fe (II) and Mn (II) followed the first-order dynamical model with the velocity constants of 0.8528~0.9937/d and 0.3001~0.3179/d, respectively.

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A dsDNA/PANI/CTS/GCE biosensor was constructed by using the biocompatible chitosan (CTS) and the polyaniline (PANI) with excellent electric catalytic properties and large specific surface areas. The electrochemical behavior of hydroquinone on biosensor and its DNA-damaging mechanisms were investigated. Results showed that the redox peak current was remarkably increased after glassy carbon electrode (GCE) was modified by PANI/CTS. The dsDNA damage by hydroquinone was concentration dependent, and increased along with the increase of hydroquinone oxidation peak current and the reduction of dsDNA guanine oxidation peak current. The linear detection range of hydroquinone with dsDNA/PANI/CTS/GCE was 1.25×10(-6)-3.2×10(-4) M, and the detection limit was 9.65×10(-7) M. It was confirmed by the UV method that applying dsDNA/PANI/CTS/GCE to monitor hydroquinone was accurate and reliable. In addition, it could be deduced that the mode of interaction between the hydroquinone and dsDNA was intercalation. The electrochemical oxidation of hydroquinone on the dsDNA/PANI/CTS/GCE electrode was an adsorption-controlled irreversible and a two-electron two-proton transfer process.

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A novel glucose biosensor was fabricated. The first layer of the biosensor was polythionine, which was formed by the electrochemical polymerisation of the thionine monomer on a glassy carbon electrode. The remaining layers were coated with chitosan-MWCNTs, GOx, and the chitosan-PTFE film in sequence. The MWCNTs embedded in FAD were like "conductive wires" connecting FAD with electrode, reduced the distance between them and were propitious to fast direct electron transfer. Combining with good electrical conductivity of PTH and MWCNTs, the current response was enlarged. The sensor was a parallel multi-component reaction system (PMRS) and excellent electrocatalytic performance for glucose could be obtained without a mediator. The glucose sensor had a working voltage of -0.42 V, an optimum working temperature of 25°C, an optimum working pH of 7.0, and the best percentage of polytetrafluoroethylene emulsion (PTFE) in the outer composite film was 2%. Under the optimised conditions, the biosensor displayed a high sensitivity of 2.80 µA mM(-1) cm(-2) and a low detection limit of 5 µM (S/N = 3), with a response time of less than 15 s and a linear range of 0.04 mM to 2.5 mM. Furthermore, the fabricated biosensor had a good selectivity, reproducibility, and long-term stability, indicating that the novel CTS+PTFE/GOx/MWCNTs/PTH composite is a promising material for immobilization of biomolecules and fabrication of third generation biosensors.

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A new manganese-oxidizing strain FM-2 was screened out from biological activated carbon (BAC) filter column and was identified as Citrobacter freundii. The results of the systematic study on this species are as follows: At 27°C, the optimum pH for Citrobacter sp. FM-2 to remove manganese was 7.0-8.0.The best removal rate of manganese under 27°C, pH 7.0 by FM-2 was reached at 4 d, being 76.2%; Compared with adsorption, biological oxidation played a dominant role in this removing process. Almost 75.7% of manganese was oxidized into oxides by Citrobacter sp and there were some particular oxides analogs generated on the bacterial surface; A 296bp DNA fragment amplified from Citrobacter sp. FM-2 revealed that this species has multicopper oxidase genes. Meanwhile, the phylogenetic tree indicated that compared with other related species, Citrobacter sp. FM-2 has its own evolutional independence.

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A strain of Pseudomonas aeruginosa (Pseudomonas sp. R1), which can efficiently decolorize reactive red X-3B, was isolated from activated sludge in a dye plant, and the decolorizing mechanism was explored in this paper. The result shows that Pseudomonas sp. R1 has very good capability for decolorization of reactive red X-3B and the decolorization rate is increased by 9.1% after optimization of the experimental parameters, which means that 89.6% of the reactive red can be removed. Investigation on decolorization mechanism showed that the decolorizing capability of Pseudomonassp. R1 was significantly affected after plasmids in Pseudomonassp. R1 were eliminated by acridine orange (AO). Meanwhile, E. coli DH5a could gain decolorizing capability after transformed with the plasmids. Plasmid elimination and transformation tests proved that the decolorizing gene in Pseudomonas sp. R1 exists in the plasmid.

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In this paper, the anti-cancer drug 6-mercaptopurine (6-MP) was taken as the detection object. The biosensor of dsDNA/GNs/chit/GCE was established using the grapheme (GNs) and chitosan (chit) as the compound modified material. The electrochemical behavior of 6-MP on the sensor was discussed, and the damage and its mechanism of 6-MP on DNA were studied. The experimental result showed that, after the modification of GNs-chit, the electrode activation area of GNs/chit/GCE increased remarkably, which was improved from 1.76cm2 to 8.64 cm2, and the responsive oxidation peak current of GNs/chit/GCE to K3[Fe(CN)6] also increased remarkably. At the meantime, it was demonstrated that DNA was effectively fixed on the GNs/chit/GCE electrode;6-MP caused obvious damage to dsDNA, and the damage degree on the adenine was bigger than that on the guanine; the interaction between 6-MP and dsDNA was preliminarily deduced as the intercalation, and its electrochemical oxidation process was an irreversible process controlled by the adsorption.

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Pure D/L-theanine enantiomers were synthesized separately, and SEM was used for their crystal-structure observation. The novel enantiomeric separating method by HPLC was established using the chiral selector of ß-CD in the mobile phase. Green tea, white tea, oolong tea, black tea and Pu-erh tea were tested for theanine enantiomers by different degrees of fermentation. The significantly higher d-enantiomeric proportion of theanine was found in white tea than the others, which was probably due to its specific processing step of withering. The effect of electrolyzed reduced water (ERW) on enantiomeric theanine and polyphenols in tea was explored. There was no change of theanine, but rather a loss of ECG (epicatechin gallate) and an increasing amount of GA (gallic acid). ERW also reduced tea cream, which contains significant amount of polyphenols, indicating its potential application in the tea-beverage industry.

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The fungicidal influencing factors of electrolyzed oxidizing water (EOW) on Candida albicans were investigated by suspension quantitative germicidal tests. Results showed that EOW possessed predominant fungicidal rate on C. albican, as high as consumately 100% after 0.5min duration of 65.5mg/L active available chlorine concentration (ACC). The fungicidal effect was promoted proportionally along with ACC but was inhibited by organic interferential bovine serum albumin (BSA). The fungicidal mechanism was also investigated at a biological molecular level by detecting series of biochemical indices. Fluorescent microscopy showed that almost all C. albicans cells were stained red in 1min, suggesting that cell membrane was one of EOW's action targets. Transmission electron microscopy (TEM) showed that EOW destroyed the cellular protective barriers and imposed some damage upon the nucleus area, which verified EOW's effects on microbial ultra-structures. EOW improved membrane permeabilities with the result that the leakages of cellular inclusions (K(+), proteins and DNA) and the conductivity increased rapidly. The dehydrogenase relative activities of C. albicans decreased by 44.0% after 10min, indicating that EOW also had a destructive effect on cellular dehydrogenase.

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Suspension quantitative germicidal test showed that electrolyzed oxidizing water (EO water) was an efficient and rapid disinfectant. Disinfection rates towards E. coli (available chlorine concentration ACC: 12.40 mg/L) and Staphylococcus aureus (ACC: 37.30 mg/L) could reach 100% at 1 and 3 min, respectively. Disinfection mechanism of EO water was investigated at a molecular biological level by detecting a series of biochemical indices. The results showed that the dehydrogenase activities of E. coli and S. aureus decreased rapidly, respectively, at the rates of 45.9% and 32% in the 1st minute treatment with EO water. EO water also improved the bacterial membrane permeability, causing the rise of conductivities and the rapid leakages of intracellular DNA, K(+), and proteins in 1 min. The leakages of DNA and K(+) tended to slow down after about 1 min while those of proteins began to decrease a little after reaching the peak values. The sodium dodecyl sulfonate polyacrylamide gel electrophoresis (SDS-PAGE) showed that EO water destroyed intracellular proteins. The protein bands got fainter and even disappeared as the treatment proceeded. EO water's effects on the bacterial ultrastructures were also verified by the transmission electronic microscopy (TEM) photos. The disinfection mechanism of EO water was composed of several comprehensive factors including the destruction of bacterial protective barriers, the increase of membrane permeability, the leakage of cellular inclusions, and the activity decrease of some key enzymes.

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This article studied the change of possible biochemistry and toxicity of emulsification wastewater before and after wet air oxidation and also studied the treating effect of wet air oxidation on emulsification wastewater after SBR process. The experimental results indicate that the toxicity of emulsification wastewater is equivalent to that of 0.12 mg/L HgCl2, while initial COD 48,000 mg x L(-1) and BOD5/COD (B/C) 0.072 3 in the inlet wastewater, and that the wastewater is highly concentrated organic wastewater. After WAO treatment, the value of BOD5/COD increases clearly. While the temperature is higher, the rise scope of B/C is bigger, and the biological toxicity reduces more. At 220 degrees C and 240 degrees C, the biological toxicity of wastewater decreases by 18.3% and 50.8% after WAO treatment, respectively. It can be seen that SBR treatment process has a perfect effect on WAO output water at 220 degrees C and has the strong anti-impact load ability. With respect to the initial COD 1500-3000 mg/L in the inlet wastewater, it exhibits the efficiency of 94.6%-96.1% COD removal. While initial COD 2000 mg/L in the inlet wastewater, the average COD in the outlet wastewater is 96.0 mg/L. The WAO-SBR process developed with respect to the emulsification wastewater treatment has a potential application prospect.

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