Remediation of arsenic- and nitrate-contaminated groundwater through iron-dependent autotrophic denitrifying culture.

Groundwater contamination with arsenic and nitrate poses a pressing concern for the safety of local communities. Bioremediation, utilizing Fe(II)-oxidizing nitrate reducing bacteria, shows promise as a solution to this problem. However, the relatively weak environmental adaptability of a single bacterium hampers practical application. Therefore, this study explored the feasibility and characteristics of a mixed iron-dependent autotrophic denitrifying (IDAD) culture for effectively removing arsenic and nitrate from synthetic groundwater. The IDAD biosystem exhibited stable performace and arsenic resistance, even at a high As(III) concentration of 800 µg/L. Although the nitrogen removal efficiency of the IDAD biosystem decreased from 71.4% to 64.7% in this case, the arsenic concentration in the effluent remained below the standard (10 µg/L) set by WHO. The crystallinity of the lepidocrocite produced by the IDAD culture decreased with increasing arsenic concentration, but the relative abundance of the key iron-oxidizing bacteria norank_f_Gallionellaceae in the culture showed an opposite trend. Metagenomic analysis revealed that the IDAD culture possess arsenic detoxification pathways, including redox, methylation, and efflux of arsenic, which enable it to mitigate the adverse impact of arsenic stress. This study provides theoretical understanding and technical support for the remediation of arsenic and nitrate-contaminated groundwater using the IDAD culture.

High-efficiency all fluorescence white OLEDs with high color rendering index by manipulating excitons in co-host recombination layers.

All fluorescence white organic light-emitting diodes (WOLEDs) based on thermally activated delayed fluorescence (TADF) emitters are an attractive route to realize highly efficient and high color quality white light sources. However, harvesting triplet excitons in these devices remains a formidable challenge, particularly for WOLEDs involving conventional fluorescent emitters. Herein, we report a universal design strategy based on a co-host system and a cascaded exciton transfer configuration. The co-host system furnishes a broad and charge-balanced exciton generation zone, which simultaneously endows the devices with low efficiency roll-off and good color stability. A yellow TADF layer is put forward as an intermediate sensitizer layer between the blue TADF light-emitting layer (EML) and the red fluorescence EML, which not only constructs an efficient cascaded Förster energy transfer route but also blocks the triplet exciton loss channel through Dexter energy transfer. With the proposed design strategy, three-color all fluorescence WOLEDs reach a maximum external quantum efficiency (EQE) of 22.4% with a remarkable color rendering index (CRI) of 92 and CIE coordinates of (0.37, 0.40). Detailed optical simulation confirms the high exciton utilization efficiency. Finally, by introducing an efficient blue emitter 5Cz-TRZ, a maximum EQE of 30.1% is achieved with CIE coordinates of (0.42, 0.42) and a CRI of 84 at 1000 cd m-2. These outstanding results demonstrate the great potential of all fluorescence WOLEDs in solid-state lighting and display panels.

Epidemiological surveillance of low pathogenic avian influenza virus (LPAIV) from poultry in Guangxi Province, Southern China.

Low pathogenic avian influenza virus (LPAIV) usually causes mild disease or asymptomatic infection in poultry. However, some LPAIV strains can be transmitted to humans and cause severe infection. Genetic rearrangement and recombination of even low pathogenic influenza may generate a novel virus with increased virulence, posing a substantial risk to public health. Southern China is regarded as the world "influenza epicenter", due to a rash of outbreaks of influenza in recent years. In this study, we conducted an epidemiological survey of LPAIV at different live bird markets (LBMs) in Guangxi province, Southern China. From January 2009 to December 2011, we collected 3,121 cotton swab samples of larynx, trachea and cloaca from the poultry at LBMs in Guangxi. Virus isolation, hemagglutination inhibition (HI) assay, and RT-PCR were used to detect and subtype LPAIV in the collected samples. Of the 3,121 samples, 336 samples (10.8%) were LPAIV positive, including 54 (1.7%) in chicken and 282 (9.1%) in duck. The identified LPAIV were H3N1, H3N2, H6N1, H6N2, H6N5, H6N6, H6N8, and H9N2, which are combinations of seven HA subtypes (H1, H3, H4, H6, H9, H10 and H11) and five NA subtypes (N1, N2, N5, N6 and N8). The H3 and H9 subtypes are predominant in the identified LPAIVs. Among the 336 cases, 29 types of mixed infection of different HA subtypes were identified in 87 of the cases (25.9%). The mixed infections may provide opportunities for genetic recombination. Our results suggest that the LPAIV epidemiology in poultry in the Guangxi province in southern China is complicated and highlights the need for further epidemiological and genetic studies of LPAIV in this area.

[Development of a GeXP assay for simultaneous differentiation of six chicken respiratory viruses].

A GeXP based multiplex PCR assay was developed to simultaneously detect six different chicken respiratory viruses including H5, H7, H9 subtypes of avian influenza virus(AIV), new castle disease virus (NDV), infectious bronchitis virus(IBV) and infectious laryngotracheitis virus(ILTV). According to the conserved sequences of genes of each pathogen, seven pairs of specific primers were designed, and the reaction conditions were optimized. The specificity and accuracy of GeXP were examined using samples of single and mixed infections of virus. The sensitivity was evaluated by performing the assay on serial 10-fold dilutions of cloned plasmids. To further evaluate the reliability, thirty-four clinical samples were detected by GeXP. The corresponding specific fragments of genes were amplified. The detection limit of GeXP was 10(2) copies/microL when all of 7 pre-mixed plasmids containing target genes of six chicken respiratory viruses were present. In the detection of thirty-four clinical samples, the results of GeXP were accorded with the viral isolation completely. In conclusion, this GeXP assay is a rapid, specific, sensitive and high-throughput method for the detection of chicken respiratory virus infections. It can be applied in rapid differential diagnosis for clinical samples, and also provide an effective tool to prevent and control chicken respiratory diseases with similar clinical symptoms.

[Visual detection of H1 subtype and identification of N1, N2 subtype of avian influenza virus by reverse transcription loop-mediated isothermal amplification assay].

In order to visually detect H1, N1 and N2 subtype of avian influenza virus (AIV), three reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays were developed. According to the sequences of AIV gene available in GenBank, three degenerate primer sets specific to HA gene of H1 subtype AIV, NA gene of N1 and N2 subtype AIV were designed, and the reaction conditions were optimized. The results showed that all the assays had no cross-reaction with other subtype AIV and other avian respiratory pathogens, and the detection limit was higher than that of conventional RT-PCR. These assays were performed in water bath within 50 minutes. Without opening tube, the amplification result could be directly determined by inspecting the color change of reaction system as long as these assays were fin-ished. Fourteen specimens of H1N1 subtype and eight specimens of H1N2 subtype of AIV were identified from the 120 clinical samples by RT-LAMP assays developed, which was consistent with that of virus isolation. These results suggested that the three newly developed RT-LAMEP assays were simple, specific and sensitive and had potential for visual detection of H1, N1 and N2 subtype of AIV in field.

Homologous recombination as an evolutionary force in the avian influenza A virus.

Avian influenza A viruses (AIVs), including the H5N1, H9N2, and H7N7 subtypes, have been directly transmitted to humans, raising concerns over the possibility of a new influenza pandemic. To prevent a future avian influenza pandemic, it is very important to fully understand the molecular basis driving the change in AIV virulence and host tropism. Although virulent variants of other viruses have been generated by homologous recombination, the occurrence of homologous recombination within AIV segments is controversial and far from proven. This study reports three circulating H9N2 AIVs with similar mosaic PA genes descended from H9N2 and H5N1. Additionally, many homologous recombinants are also found deposited in GenBank. Recombination events can occur in PB2, PB1, PA, HA, and NP segments and between lineages of the same/different serotype. These results collectively demonstrate that intragenic recombination plays a role in driving the evolution of AIVs, potentially resulting in effects on AIV virulence and host tropism changes.