Rapid enrichment of AnAOB with a novel vermiculite/tourmaline modification technology for enhanced DEAMOX process.

The DEnitrifying AMmonium OXidation (DEAMOX) has been proven to be a promising process treating contaminated surface water containing ammonia and nitrate, while the enrichment of the slow-growing anammox bacteria (AnAOB) remains a challenge. In this study, a novel polyurethane-adhesion vermiculite/tourmaline (VTP) modified carrier was developed to achieve effective enrichment of AnAOB. The results demonstrated that the VTP-1 (vermiculite: tourmaline =1:1) system exhibited the greatest performance with the total nitrogen removal efficiency reaching 87.6% and anammox contributing 63% to nitrogen removal. Scanning electron microscope analysis revealed the superior biofilm structure of the VTP-1 carrier, providing attachment for AnAOB. The addition of VTP-1 promoted the secretion of EPS (extracellular polymeric substances) by microorganisms, which increased to 85.34 mg/g VSS, contributing to the aggregation of anammox cells. The favorable substrate microenvironment created by NH4+ adsorption and NO2- supply via partial denitrification process facilitated the growth of AnAOB. The relative abundance of Candidatus Brocadia and Thauera increased from 0.04% and 0.3% to 1.03% and 2.06% in the VTP-1 system, respectively. This study sheds new light on the anammox biofilm formation and provides a valid approach to initiate the DEAMOX process for low nitrogen polluted water treatment.

Effects of Simulated Acid Rain on Photosynthesis in Pinus massoniana and Cunninghamia lanceolata in Terms of Prompt Fluorescence, Delayed Fluorescence, and Modulated Reflection at 820 nm.

The effects of simulated acid rain (SAR) on the photosynthetic performance of subtropical coniferous species have not been thoroughly investigated. In this study, we treated two coniferous species, Pinus massoniana (PM) and Cunninghamia lanceolata (CL), with four gradients of SAR and then analyzed their photosynthetic activities through measurements of gas exchange, prompt fluorescence (PF), delayed fluorescence (DF), and modulated reflection at 820 nm (MR820). Gas exchange analysis indicated that the decrease in the net photosynthetic rate (Pn) in PM and CL was unrelated to stomatal factors. For the PF transients, SAR induced positive K-band and L-band, a significant reduction in photosynthetic performance index (PIABS), the quantum yield of electron transfer per unit cross-section (ETO/CSm), and maximal photochemical efficiency of photosystem II (Fv/Fm). Analysis of the MR820 kinetics showed that the re-reduction kinetics of PSI reaction center (P700+) and plastocyanin (PC+) became slower and occurred at later times under SAR treatment. For the DF signals, a decrease in the amplitude of the DF induction curve reduced the maximum value of DF (I1). These results suggested that SAR obstructed photosystem II (PSII) donor-side and acceptor-side electron transfer capacity, impaired the connectivity between PSII and PSI, and destroyed the oxygen-evolving complex (OEC). However, PM was better able to withstand SAR stress than CL, likely because of the activation of a protective mechanism.

Robust and high-efficient nitrogen removal from real sewage and waste activated sludge (WAS) reduction in zero-external carbon PN/A combined with in-situ fermentation-denitrification process under decreased temperatures.

Despite the advantages of the combined anammox and fermentation-driven denitrification process in nitrogen removal and energy consumption, stable performance at decreased temperatures remains a challenge. In this study, a robust and high-efficient nitrogen removal efficiency (95.0-93.1 âˆ¼ 86.8-93.4%) with desirable effluent quality (3.0-4.1 âˆ¼ 7.9-4.9 mg/L) under long-term decreased temperatures (30 °C→25 °C→20 °C) was achieved in a zero-external carbon Partial Nitritation/Anammox combined with in-situ sludge Fermentation-Denitrification process treating sewage. Excellent sludge reduction averaged at 14.9% assuming no microbial growth. Increased hzsB mRNA (2.2-fold) and reduced Ea (80.9 kJ/mol) proved resilient anammox to lower temperature. RT-qPCR tests revealed increased NarG/NirK (5.1) and NarG/NirS (4.9) mRNA at 20 °C, suggesting higher NO3-→NO2- over NO2-→N2 pathway. Metagenomics unraveled dominant anammox bacteria (Candidatus_Brocadia, 2.27%), increased denitritation bacteria containing more NarG (Hyphomicrobium, 0.8%), fatty acid biosynthesis and CAZymes genes. Enhanced denitritation with recovered organics from sludge reserved nitrite for anammox and facilitated higher anammox contribution to N removal at 20 °C (42.4%) than 30 °C (39.5%). This study proposed an innovative low-temperature strategy for in-situ sludge fermentation, and demonstrated stability of advanced municipal wastewater treatment and sludge disposal through energy savings and carbon recovery under decreased temperatures.

Linkages between Plant Community Composition and Soil Microbial Diversity in Masson Pine Forests.

Plant species identity influences soil microbial communities directly by host specificity and root exudates, and indirectly by changing soil properties. As a native pioneer species common in early successional communities, Masson pine (Pinus massoniana) forests are widely distributed in subtropical China, and play a key role in improving ecosystem productivity. However, how pine forest composition, especially the dominance of plant functional groups, affects soil microbial diversity remains unclear. Here, we investigated linkages among woody plant composition, soil physicochemical properties, and microbial diversity in forests along a dominance gradient of Masson pine. Soil bacterial and fungal communities were mainly explained by woody plant community composition rather than by woody species alpha diversity, with the dominance of tree (without including shrub) species and ectomycorrhizal woody plant species accounting for more of the variation among microbial communities than pine dominance alone. Structural equation modeling revealed that bacterial diversity was associated with woody plant compositional variation via altered soil physicochemical properties, whereas fungal diversity was directly driven by woody plant composition. Bacterial functional groups involved in carbohydrate and amino acid metabolism were negatively correlated with the availability of soil nitrogen and phosphorus, whereas saprotrophic and pathogenic fungal groups showed negative correlations with the dominance of tree species. These findings indicate strong linkages between woody plant composition than soil microbial diversity; meanwhile, the high proportion of unexplained variability indicates great necessity of further definitive demonstration for better understanding of forest-microbe interactions and associated ecosystem processes.

Efficient nitrogen removal in a total floc sludge system from domestic wastewater with low C/N: High anammox nitrogen removal contribution driven by endogenous partial denitrification.

Since unsustainable partial nitrification prone to unstable nitrogen removal rates, cultivation and enrichment of AnAOB, further improve autotrophic nitrogen removal contribution have been challenges in the mainstream anammox process. This study proposed a new strategy to enrich AnAOB motivated by endogenous partial denitrification (EPD) in total floc sludge system through the AOA process with sustainable nitrification. The results showed that in the presence of NH4+ and NO3- at the anoxic stage of N-EPDA, Ca. Brocadia was enriched (0.005%→0.92%) in floc sludge via internal carbon source metabolism of EPD. The C/N and temperature of N-EPDA were also optimized to achieve higher activities of EPD and anammox. The N-EPDA was operated at low C/N ratio (3.1) with anammox nitrogen removal contribution of 78% during the anoxic stage, Eff.TIN of 8.3 mg/L and NRE of 83.5% during phase III, achieved efficient autotrophic nitrogen removal and AnAOB enrichment in the absence of partial nitrification.

Oral digoxin effects on exercise performance, K+ regulation and skeletal muscle Na+ ,K+ -ATPase in healthy humans.

We investigated whether digoxin lowered muscle Na+ ,K+ -ATPase (NKA), impaired muscle performance and exacerbated exercise K+ disturbances. Ten healthy adults ingested digoxin (0.25 mg; DIG) or placebo (CON) for 14 days and performed quadriceps strength and fatiguability, finger flexion (FF, 105%peak-workrate , 3 × 1 min, fourth bout to fatigue) and leg cycling (LC, 10 min at 33% V O 2 peak ${\rm{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{peak}}}$ and 67% V O 2 peak ${\rm{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{peak}}}$ , 90% V O 2 peak ${\rm{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{peak}}}$ to fatigue) trials using a double-blind, crossover, randomised, counter-balanced design. Arterial (a) and antecubital venous (v) blood was sampled (FF, LC) and muscle biopsied (LC, rest, 67% V O 2 peak ${\rm{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{peak}}}$ , fatigue, 3 h after exercise). In DIG, in resting muscle, [3 H]-ouabain binding site content (OB-Fab ) was unchanged; however, bound-digoxin removal with Digibind revealed total ouabain binding (OB+Fab ) increased (8.2%, P = 0.047), indicating 7.6% NKA-digoxin occupancy. Quadriceps muscle strength declined in DIG (-4.3%, P = 0.010) but fatiguability was unchanged. During LC, in DIG (main effects), time to fatigue and [K+ ]a were unchanged, whilst [K+ ]v was lower (P = 0.042) and [K+ ]a-v greater (P = 0.004) than in CON; with exercise (main effects), muscle OB-Fab was increased at 67% V O 2 peak ${\rm{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{peak}}}$ (per wet-weight, P = 0.005; per protein P = 0.001) and at fatigue (per protein, P = 0.003), whilst [K+ ]a , [K+ ]v and [K+ ]a-v were each increased at fatigue (P = 0.001). During FF, in DIG (main effects), time to fatigue, [K+ ]a , [K+ ]v and [K+ ]a-v were unchanged; with exercise (main effects), plasma [K+ ]a , [K+ ]v , [K+ ]a-v and muscle K+ efflux were all increased at fatigue (P = 0.001). Thus, muscle strength declined, but functional muscle NKA content was preserved during DIG, despite elevated plasma digoxin and muscle NKA-digoxin occupancy, with K+ disturbances and fatiguability unchanged. KEY POINTS: The Na+ ,K+ -ATPase (NKA) is vital in regulating skeletal muscle extracellular potassium concentration ([K+ ]), excitability and plasma [K+ ] and thereby also in modulating fatigue during intense contractions. NKA is inhibited by digoxin, which in cardiac patients lowers muscle functional NKA content ([3 H]-ouabain binding) and exacerbates K+ disturbances during exercise. In healthy adults, we found that digoxin at clinical levels surprisingly did not reduce functional muscle NKA content, whilst digoxin removal by Digibind antibody revealed an ∼8% increased muscle total NKA content. Accordingly, digoxin did not exacerbate arterial plasma [K+ ] disturbances or worsen fatigue during intense exercise, although quadriceps muscle strength was reduced. Thus, digoxin treatment in healthy participants elevated serum digoxin, but muscle functional NKA content was preserved, whilst K+ disturbances and fatigue with intense exercise were unchanged. This resilience to digoxin NKA inhibition is consistent with the importance of NKA in preserving K+ regulation and muscle function.

Rapid cultivation and enrichment of anammox bacteria solely using traditional activated sludge as inoculum and biocarrier in low-strength real sewage treatment.

In low-ammonia sewage anammox process, cultivation and enrichment of anammox bacteria (AnAOB) is a challenge especially from traditional activated sludge. To this end, a novel strategy solely using activated sludge as inoculum and biocarrier in a dynamic fixed-bed reactor was proposed in this study. During 115-day operation, excellent performance was achieved with influent total inorganic nitrogen (TIN) and effluent TIN of 55.3 mg·L-1 and 4.1 mg·L-1, respectively. Rapid enrichment of AnAOB (doubling time: 8.5 days) was demonstrated by augmented specific anammox activity (trace value to 1.85 mg N·g VSS-1·h-1) and increased hzsB gene number (106 to 109 copies·g-1 dry sludge), with predominance of Candidatus_Brocadia. Large-flocs aggregate was the primary habitat for AnAOB with highest abundance and capacity. The distinctive sludge properties, symbiotic microbial interactions and dynamic operation scheme facilitated AnAOB growth and retention. This study provides a simple, economic and workable approach for the start-up of mainstream anammox process.

Coupling fine Pt nanoparticles and Co-Nx moiety as a synergistic bi-active site catalyst for oxygen reduction reaction in acid media.

Fabricating high-efficiency catalysts of Pt nanoparticles coupled with single-atom sites (MNC) attracts intensive attention to accelerate the oxygen reduction reaction (ORR). Here we rationally design the low-Pt hybrid catalyst containing fine Pt nanoparticles coupled with Co-Nx moieties via a microwave-assisted heating process. The well-dispersed Pt nanoparticles are anchored by CoNC supports because of the metal-support interaction. Furthermore, the Co-Nx moiety acts as an electron donor to regulate the electronic structure of Pt through the electron synergistic effect, moderating the adsorption energy of oxygen intermediates on Pt sites, and then increasing the intrinsic activity of Pt. In addition, the overflow effect from CoNC to Pt facilitates a nearly four-electron process and enhances the kinetics of ORR. In acid media, the optimized 10% Pt/CoNC hybrid catalysts with Pt nanoparticles size (2.18 nm) exhibit improved ORR activity and robust durability, delivering a half-wave potential (E1/2) of 0.886 V and negligible loss after accelerated durability test, exceeding the best-in-class commercial Pt/C. The finding of the synergy between CoNC supports and Pt nanoparticles offers a novel ideation to construct various low-loading Pt-based hybrid catalysts.

Antimicrobial and immunomodulatory activity of beta-defensin from the Chinese spiny frog (Quasipaa spinosa).

The ß-defensins are important components of the vertebrate innate immune system. While mammalian ß-defensins have wide-ranging antibacterial and immunomodulatory activities, those of amphibians remain largely uncharacterised. In this study, ß-defensin cDNA was identified from the skin transcriptome of the Chinese spiny frog Quasipaa spinosa. This ß-defensin (QS-BD) consists of a signal and a mature peptide. Sequence alignments with other amphibian ß-defensins showed conservation of the functional mature peptide and that its closest relative is ß-defensin from Zhangixalus puerensis. Synthetic QS-BD showed antibacterial activity against Vibrio vulnificus, Vibrio harveyi, Streptococcus iniae, and Aeromonas hydrophila. QS-BD showed bactericidal activity by destroying the cell membrane integrity, but did not hydrolyse genomic DNA. QS-BD treatment promoted respiratory bursts and upregulated the expression of interleukin-1ß and tumour necrosis factor-α in the murine leukemic monocyte/macrophage cell line RAW264.7. This is the first demonstration of immunomodulatory activity by an amphibian ß-defensin.

A Gas-Phase Migration Strategy to Synthesize Atomically Dispersed Mn-N-C Catalysts for Zn-Air Batteries.

Mn and N codoped carbon materials are proposed as one of the most promising catalysts for the oxygen reduction reaction (ORR) but still confront a lot of challenges to replace Pt. Herein, a novel gas-phase migration strategy is developed for the scale synthesis of atomically dispersed Mn and N codoped carbon materials (g-SA-Mn) as highly effective ORR catalysts. Porous zeolitic imidazolate frameworks serve as the appropriate support for the trapping and anchoring of Mn-containing gaseous species and the synchronous high-temperature pyrolysis process results in the generation of atomically dispersed Mn-Nx active sites. Compared to the traditional liquid phase synthesis method, this unique strategy significantly increases the Mn loading and enables homogeneous dispersion of Mn atoms to promote the exposure of Mn-Nx active sites. The developed g-SA-Mn-900 catalyst exhibits excellent ORR performance in the alkaline media, including a high half-wave potential (0.90 V vs reversible hydrogen electrode), satisfactory durability, and good catalytic selectivity. In the practical application, the Zn-air battery assembled with g-SA-Mn-900 catalysts shows high power density and prominent durability during the discharge process, outperforming the commercial Pt/C benchmark. Such a gas-phase synthetic methodology offers an appealing and instructive guide for the logical synthesis of atomically dispersed catalysts.

A novel strategy for enhancing the partial denitrification to treat domestic wastewater by feeding sludge fermentation liquid.

Partial-denitrification (PD; NO3-→NO2-) has recently been proposed to be a feasible choice of NO2--N supply for anammox bacteria. In this study, an aerobic/anoxic process for treating domestic wastewater was operated for 176 days to evaluate the feasibility of using sludge fermentation liquid for partial denitrification of the wastewater. Results show that, with the ratio of C/N (COD/ NO3--N) increased at anoxic stage, the average NO2--N concentration in the effluent and nitrate-to-nitrite transformation ratio (NTR) at anoxic stage showed relative growth. High-throughput sequencing analysis demonstrated that the enhancement of PD can be explained by the increases of Thauera, Paracoccus and Enterobacteriaceae. Moreover, Candidatus_Brocadia (0.13%) was detected as the predominant anammox bacteria. Ex-situ isotopic tracing technique analysis assessed that the ratio of anammox role (ra%) was 7.29%. This study has a great potential for being coupled with the anammox bacteria for advanced nitrogen removal.

Advanced non-noble materials in bifunctional catalysts for ORR and OER toward aqueous metal-air batteries.

The catalyst in the oxygen electrode is the core component of the aqueous metal-air battery, which plays a vital role in the determination of the open circuit potential, energy density, and cycle life of the battery. For rechargeable aqueous metal-air batteries, the catalyst should have both good oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic performance. Compared with precious metal catalysts, non-precious metal materials have more advantages in terms of abundant resource reserves and low prices. Over the past few years, great efforts have been made in the development of non-precious metal bifunctional catalysts. This review selectively evaluates the advantages, disadvantages and development status of recent advanced materials including pure carbon materials, carbon-based metal materials and carbon-free materials as bifunctional oxygen catalysts. Preliminary improvement strategies are formulated to make up for the deficiency of each material. The development prospects and challenges facing bifunctional catalysts in the future are also discussed.

[Toxicity of Chromium to Root Growth of Barley as Affected by Chromium Speciation and Soil Properties].

Tri-and hexavalent chromium have different chemical properties, and their levels of toxicity to plants are different. However, there is no limit set by the soil environmental quality risk control standard for Cr(Ⅲ) or Cr(Ⅵ). Therefore, studying the ecological toxicity of Cr has important implications for protecting the environment. Based on the dynamics of the Cr(Ⅲ) and Cr(Ⅵ) levels in soil solution collected from eight soils, the toxicity thresholds of the two Cr forms to barley roots were investigated through model calculation and correlation analysis under different soil properties. The results showed that both Cr forms and the soil properties had significant effects on the root length of barley. The effective concentrations of Cr(Ⅲ) added to the soils that led to 10% inhibition (EC10), 50% inhibition (EC50), and no-observed-effect concentrations (NOEC) were significantly higher than those of Cr(Ⅵ). The EC50 of Cr(Ⅲ) ranged from 298.8 to 2014.1 mg·kg-1 (6.7-fold variation); the EC50 of Cr(Ⅵ) ranged from 8.0 to 126.6 mg·kg-1 (15.8-fold variation). Under the same soil conditions, the EC50 of Cr(Ⅲ) was 2.8 to 101.7 times higher than that of Cr(Ⅵ), suggesting the higher phytotoxicity of Cr(Ⅵ) than Cr(Ⅲ). Correlation analysis showed that the pH and soil organic matter were the main factors that influenced the Cr toxicity thresholds, as indicated by the root length of barley. The concentration of chromium in the soil solution was below the detection limit of the TAS-990 when Cr(Ⅲ) was applied at 1280 mg·kg-1 (or less) to soils, whereas for Cr(Ⅵ), the level was 40 mg·kg-1 (or less). Cr(Ⅲ) adsorption to the soil was significantly stronger than that of Cr(Ⅵ). The toxicity of Cr(Ⅵ) was significantly higher than that of Cr(Ⅲ), which was also influenced by soil properties.

Performance of the anammox process treating low-strength municipal wastewater under low temperatures: Effect of undulating seasonal temperature variation.

In the anammox process treating low-strength municipal wastewater, the effect of common seasonal temperature variation (15.1 °C-22.2 °C) on performance was studied. In autumn and winter, the nitrogen removal rate (NRR) decrement of 0.038kgN/(m3·d) (17.9 °C â†’ 15.1 °C) was nearly threefold higher than 0.014kgN/(m3·d) (22.2 °C â†’ 17.9 °C), which showed that lower temperature laid more negative impact on nitrogen removal. 15N isotope tracing tests confirmed that the contribution of denitrification to nitrogen removal was far less than anammox, and anammox contributed more at 15.1 °C (91.7%) than 21.9 °C (78.9%). Anammox bacteria could adapt to lower temperature after short-term acclimatization, especially the dominant genus Ca. Brocadia increased from 1.8% to 2.5% and its abundance was significantly correlated with nitrogen consumption (p < 0.05). Above findings suggest that the adaptability of Ca. Brocadia could provide the possibility to maintain nitrogen removal performance at lower temperature. In spring, the improved maximum anammox activity from 2.85 to 3.23mgNH4+-N/(gVSS·h) indicated the recovered removal capacity.

Recovering partial nitritation in a PN/A system during mainstream wastewater treatment by reviving AOB activity after thoroughly inhibiting AOB and NOB with free nitrous acid.

Starting up or recovering partial nitritation is a major challenge for achieving or maintaining stable partial nitritation/anammox (PN/A) during mainstream wastewater treatment. This study presents a novel strategy for recovering the nitrite pathway by selectively reviving ammonium oxidizing bacteria (AOB) after thoroughly inhibiting AOB and nitrite oxidizing bacteria (NOB) using free nitrous acid (FNA). A sequencing batch reactor was operated for PN/A to treat real domestic wastewater for 423 days, during which twice FNA treatment was temporarily implemented. Results showed that with a single 0.45 mg/L FNA treatment on flocculent sludge, the NO3--N concentration during the aerobic period showed an uptrend again and the partial nitritation performance was deteriorated. In contrast, 1.35 mg/L FNA treatment induced the inhibition of both AOB and NOB leading to regressive ammonium oxidation, but a subsequently higher DO (1.5 mg/L) and longer aeration duration recovered partial nitritation. For the relative abundances of the acquired biomass related to nitrogen conversion, Nitrosomonas, Nitrospira and Nitrolancea increased to 9.65%, 10.27% and 4.35%, respectively, at the beginning of the 1.35 mg/L FNA treatment, and Nitrospira and Nitrolancea decreased to 2.80% and 0.03% whereas Nitrosomonas declined to 8.71% after 76 days. Ca. Brocadia showed less resilience after the 1.35 mg/L FNA treatment, with the relative abundance decreasing from 13.38% to 0.62% due to insufficient nitrite. Molecular ecological network analysis indicates that among anammox taxa, Ca. Kuenenia and Ca. Brocadia formed important links with other N cycle processes. Moreover, the proposed strategy shows operational flexibility because it can be easily used to control NOB in mainstream PN/A applications offered by flocculent sludge systems.

A sponge-templated sandwich-like cobalt-embedded nitrogen-doped carbon polyhedron/graphene composite as a highly efficient catalyst for Zn-air batteries.

Non-noble metal materials are regarded as the most promising catalysts for the oxygen reduction reaction (ORR) to overcome the inherent defects of Pt-based catalysts, like high cost, limited availability and insufficient stability. Here, we fabricate sandwich-like Co encapsulated nitrogen doped carbon polyhedron/graphene (s-Co@NCP/rGO) via a facile and scalable strategy by loading Co-based zeolitic imidazolate framework (ZIF-67) and graphene oxide (GO) layers individually on a polyurethane (PU) sponge template. The 3D sandwich structure is maintained with the assistance of the sponge template, which promotes the uniform dispersion of ZIF-67-derived Co embedded nitrogen doped carbon polyhedra (Co@NCP) and prevents the graphene plates from agglomerating during the annealing process. The final product demonstrates considerable catalytic performance for the ORR with a half-wave potential of 0.85 V, preferable stability and increased poisoning tolerance by comparison to 20 wt% Pt/C, which stems from the 3D sandwich-like structure, N/Co-doping effect, large accessible surface area and hierarchical porous structures. The excellent ORR performance of the catalysts means that they can be utilised in a Zn-air battery as cathode catalysts. During such a demonstration, s-Co@NCP/rGO shows a high open-circuit voltage of 1.466 V, remarkable long-term durability and an outstanding peak power density of 186 mV cm-2, which shows its high potential as a prospective alternative for widespread practical application in the field of non-noble metal ORR catalysts.

Free nitrous acid pretreatment of sludge to achieve nitritation: The effect of sludge concentration.

This study investigated the effect of sludge concentration (expressed by mixed liquor volatile suspended solids, MLVSS) on free nitrous acid (FNA) pretreatment strategy to achieve nitritation. Results showed when FNA was 0.308 mgHNO2-N/L, nitrite oxidizing bacteria (NOB) activity increased by 70.2% as MLVSS increased from 8.4 to 16.8 g/L. Nitrite accumulation ceased as MLVSS increased to 12.6 g/L, indicating that FNA inhibition of NOB gradually weakened with increasing MLVSS. When FNA was higher than 0.770 mgHNO2-N/L, NOB activity was completely inhibited and the effect of MLVSS on FNA inhibition was negligible, with nitrite accumulation potential (NAP) varying from 88.1% to 90.0%. Mechanism investigation demonstrated flocs sizes distinctly declined, with more extracellular polymeric substances (EPS) released to resist FNA inactivation. Linear fitting showed NAP increased with FNA/MLVSS increment. Therefore, MLVSS affected FNA pretreatment performance, with FNA/MLVSS proposed as a more valuable criterion in FNA pretreatment strategy development, than the solely FNA.

Cobalt and Nitrogen Codoped Carbon Nanosheets Templated from NaCl as Efficient Oxygen Reduction Electrocatalysts.

The oxygen reduction reaction (ORR) in a cathode is an essential component of many electrochemical energy storage and conversion systems. Two-dimensional materials are beneficial for electron conduction and mass transport with high density, showing prominent electrochemical catalytic performance towards the ORR. Herein, a simple NaCl-assisted method to synthesize cobalt-nitrogen-doped carbon materials (CoNC), which present prominent performance towards the ORR in alkaline media, is described. The utilization of the NaCl template endows the product with a large specific surface area of 556.4 m2 g-1 , as well as good dispersion of cobalt nanoparticles. CoNC-800@NaCl (800 indicates the calcination temperature in °C) displays an excellent onset potential of 0.94 V (vs. a reversible hydrogen electrode), which is close to that of commercial Pt/C. Additionally, CoNC-800@NaCl also exhibits better long-term durability and methanol tolerance than that of Pt/C. The high-performance CoNC-800@NaCl catalyst provides a hopeful alternative to noble-metal catalysts for the ORR in practical applications.

Impaired exercise performance and muscle Na(+),K(+)-pump activity in renal transplantation and haemodialysis patients.

BACKGROUND: We examined whether abnormal skeletal muscle Na(+),K(+)-pumps underlie impaired exercise performance in haemodialysis patients (HDP) and whether these are improved in renal transplant recipients (RTx). METHODS: Peak oxygen consumption ( O(2peak)) and plasma [K(+)] were measured during incremental exercise in 9RTx, 10 HDP and 10 healthy controls (CON). Quadriceps peak torque (PT), fatigability (decline in strength during thirty contractions), thigh muscle cross-sectional area (TMCSA) and vastus lateralis Na(+),K(+)-pump maximal activity, content and isoform (α(1)-α(3), ß(1)-ß(3)) abundance were measured. RESULTS: O(2peak) was 32 and 35% lower in RTx and HDP than CON, respectively (P < 0.05). PT was less in RTx and HDP than CON (P < 0.05) but did not differ when expressed relative to TMCSA. Fatigability was ∼1.6-fold higher in RTx (24 ± 11%) and HDP (25 ± 4%) than CON (15 ± 5%, P < 0.05). Na(+),K(+)-pump activity was 28 and 31% lower in RTx and HDP, respectively than CON (P < 0.02), whereas content and isoform abundance did not differ. Pooled (n = 28) O(2peak) correlated with Na(+),K(+)-pump activity (r = 0.45, P = 0.02). CONCLUSIONS: O(2peak) and muscle Na(+),K(+)-pump activity were depressed and muscle fatigability increased in HDP, with no difference observed in RTx. These findings are consistent with the possibility that impaired exercise performance in HDP and RTx may be partially due to depressed muscle Na(+),K(+)-pump activity and relative TMCSA.

The sorption behavior of DDT onto sediment in the presence of surfactant cetyltrimethylammonium bromide.

The sorption behavior of p,p'- and o,p'-dichlorodiphenyltrichloroethane (DDT) in the presence of a cationic surfactant cetyltrimethylammonium bromide (CTAB) on sediment was studied. Batch experiments were carried out to investigate the kinetics and thermodynamics of the process. The kinetic behavior of these three chemicals on sediment was described by pseudo-second-order kinetic equations, and the isotherms followed the Freundlich model well. The presence of CTAB was able to remarkably accelerate and enhance the sorption of DDT, whereas DDT showed no effect on the sorption of CTAB in our considered concentration ranges. The thermodynamic parameters, such as standard enthalpy change (ΔH0), standard entropy change (ΔS0) and standard Gibbs free energy change (ΔG0) showed that the sorption process of p,p'- and o,p'-DDT was physical, spontaneous and exothermic, and the randomness at the solid-liquid interface increased during the process. In the presence of CTAB, the sorption of DDT showed significantly negative ΔG0 and ΔH0 values.