Bioelectrochemically-assisted ammonia recovery from dairy manure.

The sustainability of direct land application of dairy manure is challenged by significant nutrient losses. Bioelectrochemical systems for ammonia recovery offer a manure management strategy that can recover both ammoniacal and organic nitrogen as a stable ammonia fertilizer. In this research, a microbial fuel cell (MFC) was used to treat two types of dairy manure under a variety of imposed anode compartment conditions. The system achieved a maximum coulombic efficiency of 20 ± 18 % and exhibited both COD and total nitrogen removals of approximately 60 %. Furthermore, the MFC showed a maximum organic nitrogen removal of 73.8 ± 12.1 %, and no differences in organic nitrogen (orgN) removal were detected among different conditions tested. Decreasing concentrations of anolyte ammonia nitrogen coupled with the observed orgN removal from the anolyte indicate that the MFC is effective at recovering orgN in dairy manure as ammoniacal nitrogen in the catholyte. Additionally, ion competition between NH4+ and other relevant cations (Na+, K+, and Mg2+) for transport across the CEM was investigated, with only K+ showing minor competitive effects. Based on the results of this research, we propose three key processes and two sub-processes that contribute to the successful operation of the MFC for nitrogen recovery from dairy manure. Bioelectrochemical systems for nitrogen recovery from dairy manure offer a novel, robust technology for producing a valuable ammonia nitrogen fertilizer, a thus far untapped resource in dairy manure streams.

Selective dechlorination degradation of chlorobenzenes by dual single-atomic Fe/Ni catalyst with M-N/M-O active sites synergistic.

Removal and detoxification of chlorobenzenes have attracted public concern, multiple active sites single-atom Fe and single-atom Ni composite nitrogen-doped graphene (FeSA/CN/NiSA) cathode catalyst supplied generation and adsorption capacity of hydrogen and hydroxyl active species. M-O active sites coupled with M-N improved activity and stability of the catalyst, and decreased bond breaking energy barrier of C-Cl, FeSA/CN/NiSA-NiF cathode showed superior removal performance of chlorinated aromatic hydrocarbons (monochlorobenzene: 98.9%, dichlorobenzene: over 90.4%, trichlorobenzene: over 85.7%) and selectivity. Chlorobenzenes were dechlorinated under low stepwise voltage on the FeSA/CN/NiSA-NiF cathode. The efficiencies of stepwise dechlorination reactions of chlorobenzenes were all above 76%, Faradaic efficiencies were above 71.8%. The FeSA/CN/NiSA-NiF cathode was not sensitive to the molecular structure and has overcome the high energy barrier of chlorobenzenes molecular structure. The electrophilic attack of H*ads formed hyperconjugation bond weakened the possibility of the Cl atom forming a bond with the benzene ring, and was favorable for the Cl position to achieve single-electron transfer dechlorination. The selective stepwise dechlorination degradation of chlorobenzenes by FeSA/CN/NiSA-NiF cathode with multiple active sites demonstrated the advantaged performance of M-O and M-N active sites coupled synergistic in electrochemical reduction and degradation, providing a strategy for product-selective degradation of chlorinated aromatic hydrocarbons.

Core-shell SERS nanotags-based western blot.

Western blot (WB) is the most commonly used scheme for protein identification in life science, but it still faces great challenges in the accurate quantitative detection of low-abundance proteins. Here, we proposed a novel surface-enhanced Raman scattering-based Western blot (SERS-WB) to solve this challenge. SERS nanotags were used as quantitative labels of proteins, which were composed of gold-silver core-shell nanoparticles, and Nile blue A (NBA) molecules were anchored on the interface of the core and shell. The results show that the SERS-WB possessed excellent sensitivity with detection limit of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein of 0.15 pg, as well as wide linear dynamic range (LDR) of 382 fg to 382 ng. In addition, the target protein on nitrocellulose (NC) membrane could be directly identified by colorimetric signal due to the aggregation effect of nanoparticles, which greatly simplifies the procedure. This as-proposed strategy will bring new thoughts to technological innovation of WB.

Toxic effects of 4-methylimidazole on the maturation and fertilization of mouse oocytes.

Individuals of all ages, including children and teenagers, consume 4-methylimidazole (4-MI) in their food. 4-MI is a caramel-colored waste product that has previously been linked to human carcinogenesis and has shown possible signs of reproductive toxicity. This study aimed to determine whether 4-MI is harmful to oocytes during meiosis and fertilization. Female mice were intragastrically administered 0, 50, or 100 mg/kg body weight of 4-MI daily for 10 days. We found that 4-MI affects the quality of oocytes by affecting their meiotic ability and fertility potential. Specifically, 4-MI rendered the meiotic spindles and chromosomes less stable, which halted oocyte maturation and resulted in aneuploidy. 4-MI also slowed the decrease in the levels of cortical granules and their component ovastacin; consequently, sperms could not be bound and fertilization could not occur. We also found that mitochondrial dysfunction was associated with oocytes deterioration. This led to reactive oxygen species accumulation and cell death. Altogether, our findings reveal that the poor condition of oocytes subjected to 4-MI is primarily attributable to mitochondrial malfunction and redox alterations.

Comprehensive Analysis of the Transcriptome-Wide m6A Methylation in Mouse Pachytene Spermatocytes and Round Spermatids.

Spermatogenesis, an efficient and complex system in male germline development, requires a series of elaborately regulated genetic events in which diploid spermatogonia differentiate into haploid spermatozoa. N6-methyladenosine (m6A) is an important epigenetic RNA modification that occurs during spermatogenesis. ALKBH5 is an m6A eraser and knocking out Alkbh5 increases the level of total m6A methylation and causes male infertility. In this study, comprehensive analyses of MeRIP-seq and RNA-seq data revealed differences between wild-type (WT) and Alkbh5 knockout (KO) mice. In pachytene spermatocytes (PA), 8,151 m6A peaks associated with 9,959 genes were tested from WT and 10,856 m6A peaks associated with 10,016 genes were tested from KO mice. In the round spermatids (RO), 10,271 m6A peaks associated with 10,109 genes were tested from WT mice and 9,559 m6A peaks associated with 10,138 genes were tested from KO mice. The peaks were mainly concentrated in the coding region and the stop codon of the GGAC motif. In addition, enrichment analysis showed significant m6A methylation genes in related pathways in spermatogenesis. Furthermore, we conducted joint analyses of the m6A methylome and RNA transcription, suggesting an m6A regulatory mechanism of gene expression. Finally, seven differentially expressed mRNAs from RNA-seq data in both PA and RO were verified using qPCR. Overall, our study provides new information on m6A modification changes between WT and KO in PA and RO, and may provide new insights into the molecular mechanisms of m6A modification in germ cell development and spermatogenesis.

Stepwise dechlorination of chlorinated alkenes on an Fe-Ni/rGO/Ni foam cathode: Product control by one-electron-transfer reactions.

Research on the stepwise hydrogenation dechlorination of chlorinated alkenes forms an important basis for eliminating toxic intermediate incomplete dechlorination products. The low-cost Fe-Ni/rGO/Ni foam cathode both supplied electrons and exhibited hydrogen conversion activity, and it was an excellent tool for the study of stepwise dechlorination. Electrochemical reduction experiments were carried out on homologous chlorinated alkenes. The conditions affecting the dechlorination efficiency and the repeatability of the catalytic electrode were analyzed. The trichloroethylene (TCE) removal rates were all above 78.0% over 8 cycles. The maximum EHDC efficiency was as high as 86.1%, and the faradaic efficiency was over 78.8%. Electrochemical methods combined with the calculation of the electron transfer number are proposed to verify the good hydrogenation ability of the electrode and the stepwise reduction ability at proper voltages. The stepwise dechlorination electroreduction characteristics of chlorinated alkenes were explained. The C-Cl bond dissociation enthalpies of chlorinated alkenes were calculated by density functional theory (DFT), and the 4-Cl and 5-Cl of TCE were expected to be removed first. The stepwise cleavage of chlorinated alkenes on Fe-Ni/rGO/Ni foam during dichlorination provided a reference for controlling the reduction products of chlorinated alkenes and preventing the pollution caused by toxic intermediate products formed during incomplete dechlorination.

Dibutyltin dichloride exposure affects mouse oocyte quality by inducing spindle defects and mitochondria dysfunction.

Dibutyltin dichloride (DBTCl) is a widespread environmental pollutant that is frequently employed as a light and heat sustainer for polyvinyl chloride (PVC) plastics and is a teratogen in vivo. Nevertheless, its destructiveness in mammalian oocytes remains unclear. This study highlighted the consequences of DBTCl vulnerability on mouse oocyte. Our results revealed that exposure to 5.0 mg/kg/day of DBTCl for ten days reduced the number of mature follicles and oocytes in the ovaries and inhibited the meiotic maturation of oocytes. Single-cell transcriptomic analysis indicated that DBTCl exposure interfered with the expression of more than 400 genes in oocytes, including those involved in multiple biological pathways. Specifically, DBTCl exposure impaired spindle assembly and chromosome alignment. In addition, DBTCl exposure caused mitochondrial dysfunction, which led to the accumulation of reactive oxygen species (ROS) and induced apoptosis. In summary, our study illustrates that mitochondrial dysfunction and redox perturbation are the major causes of the reduced quality of oocytes exposed to DBTCl.

Corrigendum: Comprehensive analysis of the transcriptome-wide m6A methylation in mouse pachytene spermatocytes and round spermatids.

[This corrects the article DOI: 10.3389/fgene.2022.832677.].

Efficient and recyclable Ni-Ce-Mn-N modified ordered mesoporous carbon electrode during electrocatalytic ozonation process for the degradation of simulated high-salt phenol wastewater.

In this study, an efficient and stable NiO/CeO2/MnO2-modified nitrogen-doped ordered mesoporous carbon (NOMC) particle electrode was developed, in which the metal oxides were mosaicked within the pore channels by one-pot skeleton hybridization, and the comodification of NiO/CeO2/MnO2/N was found to improve the electrocatalytic activity and stability of the particle electrode. The improved stability of the ordered mesoporous carbon towards pore collapse was applied to the degradation of simulated high-salt phenol wastewater by an electrocatalytic ozonation process using simple binder pelletization. The modified ordered mesoporous carbon shows a specific surface area of 269.7 m2 g-1 and a pore size of 3.17 nm, and SEM and TEM were used to show that the mesoporous structure is well maintained and the metal nanoparticles are well dispersed. The electrochemically active area of the Ni2%/Ce0.5%/Mn2.5%-NOMC particle electrode reaches 224.65 mF cm-2, which indicates that NiO improves the capacitance of the ordered mesoporous carbon and accelerates the electron transfer efficiency. Encouragingly, the phenol removal efficiency is found to reach up to 93.0% for 60 min over a wide range of pH values, with an initial phenol concentration of 150 mg L-1, low current (0.03 A) and fast reaction rate (0.0895 min-1), and the presence of CeO2 ameliorates the low activity of the particle electrode under acidic conditions. These results indicate that the presence of pyridine-N and ß-MnO2 effectively mitigates carbon corrosion and improves electrode stability, as the accumulation of large amounts of ·OH at 20 min and the maintenance of a degradation efficiency of more than 90% after eight cycles provides a viable solution for the widespread practical application of ordered mesoporous carbon particle electrodes.

Combining electrokinetic treatment with modified zero-valent iron nanoparticles for rapid and thorough dechlorination of trichloroethene.

In situ injection of nanoscale zero-valent iron (nZVI) slurry is a promising method to treat chlorinated solvents represented by trichloroethylene (TCE) in groundwater. In this study, the effects of sulfidation and emulsification treatment on the performance of nZVI reductive dechlorination of TCE under enhancement by an external electric field were evaluated. The hydrophobic oil film on the surface of sulfidized and emulsified zero-valent iron (S-EZVI) can sequestrate more than one-fifth of the unreacted TCE in the early stage of the experiment (at 5 min). The FeS layer formed on the surface of S-EZVI can facilitate the electron-transfer process and reduce the degree of corrosion of Fe0 with water by 94.0%. Electric-field-enhanced S-EZVI technology can remove more than 93.1% of TCE in the pH range 6.0-9.0, and the performances in overly acid and overly alkali environments both improved. Under the optimal conditions, the TCE removal rate and reaction constant of the applied electric field group reached 96.7% and 1.6 × 10-2 L g-1 min-1, respectively, which were much higher than those of the group without an electric field (53.2% and 3.3 × 10-3 L g-1 min-1) owing to rapid concurrent hydrogenolysis of dichloroethenes and vinyl chloride, or another transformation pathway, such as direct oxidation by the anode. Thereby, this method avoids accumulation of chlorinated intermediates, especially toxic vinyl chloride. This work shows that combination technology has many characteristics that are favorable for field application, and it is expected to provide a new reference and have application value for development of in situ efficient and thorough treatment of TCE-contaminated groundwater.

Highly sensitive detection of free testosterone assisted by magnetic nanobeads and gap-enhanced SERS nanotags.

The quantitative determination of trace free testosterone (FT) is of great significance for the diagnosis of androgen-related endocrine diseases. Herein, a fascinating detection protocol was developed for highly sensitive FT analysis through a competitive immunoassay mechanism, which was composed of magnetic nanobeads (MNBs) and gap-enhanced surface enhanced Raman scattering (SERS) nanotags. With the MNBs as detection carriers, trace FT could be enriched by simple magnetic separation. The SERS nanotag constructed with silver-gold core-shell nanoparticle was acted as quantitative label, and Raman indicators were located at the interface between silver core and gold shell. It is demonstrated that the as-proposed protocol achieves high detection sensitivity for FT of 12.11 fg mL-1, and wider linear dynamic detection range (LDR) in the concentration of 100 fg mL-1 to 100 ng mL-1 with R2 value of 0.979, which is due to the enhanced Raman signal of the gap-enhanced SERS nanotag and the high surface-to-volume ratio of the MNB, respectively. Taking advantages of such sensitivity and accuracy approach, the as-developed powerful strategy presents potential applications for rapid disease diagnosis through analyzing trace levels of FT, and can also provide guidance for the exploitation of analysis project of other analytes.

Ultrasensitive and facile detection of multiple trace antibiotics with magnetic nanoparticles and core-shell nanostar SERS nanotags.

Ultrasensitive, multiplex, rapid, and accurate quantitative determination of trace antibiotics remains a challenging issue, which is of importance to public health and safety. Herein, we presented a multiplex strategy based on magnetic nanoparticles and surface-enhanced Raman scattering (SERS) nanotags for simultaneous detection of chloramphenicol (CAP) and tetracycline (TTC). In practice, SERS nanotags based on Raman reporter probes (RRPs) encoded gold-silver core-shell nanostars were used as detection labels for identifying different types of antibiotics, and the magnetic nanoparticles could be separated simply by magnetic force, which significantly improves the detection efficiency, reduces the analysis cost, and simplifies the operation. Our results demonstrate that the as-proposed assay possesses the capacities of high sensitivity and multiplexing with the limits of detection (LODs) for CAP and TTC of 159.49 and 294.12 fg mL-1, respectively, as well as good stability and reproducibility, and high selectivity and reliability. We believe that this strategy holds a great promising perspective for the detection of trace amounts of antibiotics in microsystems, which is crucial to our life. Additionally, the assay can also be used to detect other illegal additives by altering the appropriate antibodies or aptamers.

Reuse solution of hardness industrial circulating cooling water: Targeted ion-selective electro-adsorption by functionalized electrode.

A low-cost, efficient and environmentally friendly hardness ion selective electro-adsorption system for high-hardness industrial circulating cooling water reuse was constructed to simultaneously realize a high salt removal rate and hardness ion (Ca2+ and Mg2+) selection. Multiply modified graphite carbon felt (GCF) materials for both negative and positive electrodes were proposed simply and economically, and an electro-adsorption system for hardness control was assembled. The multiple modified GCF (GCFM) materials were characterized by SEM, BET and FT-IR and the electrochemical performance was tested by CV and EIS; surface properties were studied by Zeta potential; the hardness ion removal selectivity and operational stability of the electro-adsorption system were tested. Hydrophilic functional groups were introduced in GCFM electrode, GCFM exhibited a large microporosity and demonstrated stable electrochemical performance in aqueous with a specific capacitance. The hardness ion selective electro-adsorption system achieved an adsorption capacity of 58.05 mg/g per circle for calcium ions and 31.03 mg/g for magnesium ions, indicating the superior hardness ion selectivity. In the circulating cooling water at the electro-adsorption stage, the ion removal performance was over 42.1% and maintain in good stability, GCFM electrode showed excellent deionization performance and demonstrated the application potential of hardness ion selective electro-adsorption system.

Construction of heterojunction photoanode via facile synthesis of CoOx/CN nanocomposites for enhanced visible-light-driven photoelectrochemical degradation of clofibric acid.

Visible-light-driven photoelectrocatalytic (PEC) oxidation has been explored extensively to develop highly active materials. Herein, a visible-light-active p-Co3O4 and n-g-C3N4 heterojunction (CoOx/CN) photoanode, constructed by simple one-pot calcination, was shown to remove clofibric acid (CA) from water through a PEC process. Compared with pristine g-C3N4, the optimal photoanode (15%-CoOx/CN) exhibited stable and effective PEC performance and CA degradation performance, a 100-fold enhancement in photocurrent density, and around 1.5-fold decreased efficiency over 6 h. The p-n heterojunctions were shown to increased the charge density and conductivity of g-C3N4 for rapid charge transfer. Furthermore, interface contact broadened the visible light absorption and accelerated charge carrier transfer. Notably, the catalysts established p-n heterojunctions, which hindered the bulk recombination of photoinduced carriers and improved the charge separation efficiency. The CoOx/CN photoanodes showed a pair of redox peaks at a potential of 0.3 V vs. Ag/AgCl, indicating good Co3O4 redox behavior under alkaline conditions. The 15%-CoOx/CN photoanode displayed excellent PEC performance of up to 0.16 mA cm-2 in 0.1 M KOH solution at 1.23 V vs. RHE (reversible hydrogen electrode) and long-term stability for up to 12 h. The CoOx/CN photoanodes maintained excellent PEC activities for CA removal, even under acidic and alkaline conditions conditions (pH 3-10). Probable degradation pathway of CA was proposed according to the main degradation intermediates. This study shows that the synergistic effect of p-n heterojunctions in photoelectrodes provides a new approach to the rational application of new photoanode candidates and PEC performance optimization.

Single-Atom Cobalt Catalysts for Electrocatalytic Hydrodechlorination and Oxygen Reduction Reaction for the Degradation of Chlorinated Organic Compounds.

Electrochemical reduction-oxidation processes with the aid of cathode catalysts are promising technologies for the decomposition of organic compounds. High-efficiency and low-cost catalysts for electrochemical reductive dechlorination and two-electron oxygen reduction reaction (ORR) are vital to the overall degradation of chlorinated organic compounds. This study reports electrochemical dechlorination using a single-atom Co-loaded sulfide graphene (Co-SG) catalyst via atomic hydrogen generated from the electrochemical reduction of H2O and electrolysis of hydrogen. The Co-SG electrocatalyst exhibited a remarkable performance for H2O2 synthesis with a half-wave potential of 0.70 V (vs RHE) and selectivity over 90%. The high electrochemical performance was achieved for bifunctional electrocatalysis with regard to the smaller overpotentials, faster kinetics, and higher cycling stability compared to the noble metal-based electrocatalysts. In this study, 2,4-dichlorobenzoic acid was well degraded and the TOC concentration was effectively reduced. This work introduces the preparation of a new active site for high-performance single-atom catalysts and also promotes its application in the electrochemical degradation of chlorinated organic pollutants.

Charge Transport Modulation in PbSe Nanocrystal Solids by Au xAg1- x Nanoparticle Doping.

Nanocrystal (NC) solids are an exciting class of materials, whose physical properties are tunable by choice of the NCs as well as the strength of the interparticle coupling. One can consider these NCs as "artificial atoms" in analogy to the formation of condensed matter from atoms. Akin to atomic doping, the doping of a semiconducting NC solid with impurity NCs can drastically alter its electronic properties. A high degree of complexity is possible in these artificial structures by adjusting the size, shape, and composition of the building blocks, which enables "designer" materials with targeted properties. Here, we present the doping of the PbSe NC solids with a series of Au xAg1- x alloy nanoparticles (NPs). A combination of temperature-dependent electrical conductance and Seebeck coefficient measurements and room-temperature Hall effect measurements demonstrates that the incorporation of metal NPs both modifies the charge carrier density of the NC solids and introduces energy barriers for charge transport. These studies point to charge carrier injection from the metal NPs into the PbSe NC matrix. The charge carrier density and charge transport dynamics in the doped NC solids are adjustable in a wide range by employing the Au xAg1- x NP with different Au:Ag ratio as dopants. This doping strategy could be of great interest for thermoelectric applications taking advantage of the energy filtering effect introduced by the metal NPs.