The conversion pathway of NH4+ in deterioration and restoration periods. Display omitted
•Intermittent aeration restored single-stage PN/A process from nitrate build-up.•NOB accumulated under ...continuous aeration mode, Nitrospira was the dominant NOB.•Reducing DO to 0.17±0.08mg/L was failed to inhibited the NOB activity.•Sewage PN/A reactor was quickly started up by inoculating anammox sludge.
A single-stage partial nitrification-anammox (PN/A) reactor treating low-strength swage was operated for 288days to investigate the recovery of nitrogen removal from nitrate accumulation. The reactor was quickly started up by inoculating anammox sludge. However, nitrite oxidizing bacteria (NOB) abundance gradually increased on day 25, leading to high effluent nitrate concentration. Two strategies were executed to control the effluent nitrate. In strategy I, dissolved oxygen (DO) concentration was kept low (0.17±0.08mg/L), but nitrate production increased from 4.71 to 38.18mg-N/L. In strategy II, intermittent aeration operation mode (aeration 7min/anoxic 21min) was adopted, which significantly lowered the nitrate concentration to 1.3mg-N/L, indicating the NOB was inhibited. The high nitrogen removal rate of 73mg-N/(L·d) was achieved. The evolution of bacterial activity and abundance verified the changes of the nitrogen removal performance and proved the intermittent aeration strategy could successfully solve the problem of nitrate build-up in the PN/A process.
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•Microbial evolution from sidestream PN/A to mainstream PN/A was investigated.•For both side and mainstream PN/A, anammox bacteria mainly grew in granular sludge.•Ca. Kuenenia ...outcompeted Ca. Brocadia in the mainstream PN/A reactor.•Heterotrophic bacteria constitute the majority of microorganism in PN/A reactor.•Phylum Chloroflexi were enriched under mainstream conditions.
This study investigated the microbial evolution in a mainstream partial nitritation/anammox (PN/A) reactor started by inoculation from sidestream PN/A. The reactor was fed with pre-treated sewage and operated for 120 days at room temperature (24–26 °C). It was found that for both sidestream and mainstream PN/A, anammox bacteria preferentially grew in granular sludge while ammonium-oxidizing bacteria (AOB) were mainly resided in flocculent sludge. After 120 days operation, the abundance of anammox bacteria in the reactor decreased from 6.6 × 1011 to 3.2 × 1011 copies/L. Besides, a shift of dominant anammox genera from Ca. Brocadia to Ca. Kuenenia was observed. In contrast, the dominant genera of AOB was Nitrosomonas throughout the operation. Furthermore, high-throughput sequencing revealed that heterotrophs constitute the majority of microorganisms in PN/A reactor. Especially, Chloroflexi, which can utilize cell decay materials from autotrophs, were enriched under mainstream conditions. This study provided a better understanding of the microorganisms in mainstream PN/A process.
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•Partial nitritation/anammox was established in an IFAS reactor treating sewage.•Efficient nitrogen removal (TNeffluent=7.9mg/L and 82% TNremoval) was achieved.•Stable PN/A operation ...was achieved when residual ammonium was higher than 3mg/L.•Nitrate accumulated and PN/A performance declined when residual ammonium <1mg/L.
This study tested the feasibility of plug-flow integrated fixed-film activated sludge (IFAS) reactor in applying sewage partial nitritation/anammox (PN/A) process. The IFAS reactor was fed with real pre-treated sewage (C/N ratio=1.3) and operated for 200days. High nitrogen removal efficiency of 82% was achieved with nitrogen removal rates of 0.097±0.019kgN/(m3·d). Therefore, plug-flow IFAS reactor could be an alternative to applying sewage PN/A process. Besides, it was found that the stability of sewage PN/A process was significantly affected by residual ammonium. Nitrate accumulated in effluent and PN/A performance deteriorated when residual ammonium was below 1mg/L. On the contrary, long-term stable PN/A operation was achieved when residual ammonium was over 3mg/L.
•Nitritation–anammox process was obtained in a pilot-scale IFAS reactor.•Nitrogen loading rate of 1.2kgm−3d−1 was achieved with the removal efficiency of 80%.•Anammox bacteria was attached grew and ...enriched on the surface of the carrier.•Anammox granular sludge was gradually obtained due to the detachment of biofilm.
A pilot-scale activated sludge bioreactor was filled with immobile carrier to treat high ammonium wastewater. Autotrophic nitrogen elimination occurred rapidly by inoculating nitrifying activated sludge and anammox biofilm. As the ammonium loading rate increased, nitrogen removal rate of 1.2kgNm−3d−1 was obtained with the removal efficiency of 80%. Activated sludge diameter distribution profiles presented two peak values, indicating simultaneous existence of flocculent and granular sludge. Red granular sludge was observed in the reactor. Furthermore, the results of morphological and molecular analysis showed that the characteristics of granular sludge were similar to that of biofilm, while much different from the flocculent sludge. It was assumed granular sludge was formed through the continuous growth and detachment of anammox biofilm. The mechanism of granular sludge formation was discussed and the procedure model was proposed. According to the experimental results, the integrated fixed-biofilm activated sludge reactor provided an alternative to nitrogen removal based on anammox.
Abstract
The von Economo neurons (VENs) are specialized large bipolar projection neurons with restricted distribution in the human brain, and they are far more abundant in humans than in non-human ...primates. However, VEN functions remain elusive due to the difficulty of isolating VENs and dissecting their connections in the brain. Here, we combined laser-capture-microdissection with RNA sequencing to describe the transcriptomic profile of VENs from human anterior cingulate cortex (ACC). Using pyramidal neurons as reference cells, we identified 344 genes with VEN-associated expression differences, including 215 higher and 129 lower expression genes. Functional enrichment and protein-protein interaction network analyses showed that these genes with VEN-associated expression differences are involved in VEN morphogenesis and functions, such as dendrite branching and axon myelination, and many of them are associated with human social-emotional disorders. With the use of in situ hybridization and immunohistochemistry assays, we validated four novel VEN markers (VAT1L, CHST8, LYPD1, and SULF2). Collectively, we generated a full-spectrum expression profile of VENs from human ACC, greatly enlarging the pool of genes with VEN-associated expression differences that can help researchers to understand the role of VENs in normal and disordered human brains.
A theory of superconductivity based on Bose-Einstein statistics was proposed, which can lead to a formula for
T
C
(critical temperature) similar to that of BCS theory, and provide a possible ...explanation for the complexity of isotope effect and the normal state energy gap in copper-oxides. We proceeded from a 3-dimensional harmonic oscillator model to equivalent the superconducting state to a two-dimensional Bose-Einstein condensate bound longitudinally, and pointed out the application conditions of the theory. Under this scheme, we analyzed some typical structural features in copper oxides that favor the production of high-temperature superconductivity. We also discovered that combining this theory with an alternative mechanism -strong coupling to local spin configurations-provided some useful hints for exploring new superconducting materials. In addition, we pointed out a possible link between the phenomenon of superconductivity and magnetostriction, then we proposed some combinations of elements as possible candidates for high temperature superconducting materials based on those analysis.
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•Enantiomers of TF show no stereoselective photolysis and photo-induced toxicity.•TN diastereomers show stereoselective photolysis and photo-induced toxicity.•Individual chiral ...monomers possess similar photolysis mechanism as the mixture.•Main photolytic pathways for TF and TN are removal of Cl and triazole groups.•Chiral mixture and monomers exhibit enhanced photo-induced toxicity to V. fischeri.
The photochemical behaviors of chiral pollutants in aqueous solutions are rarely studied using chiral monomers, which may hamper their precise risk assessment and lead to suspicious conclusions. In this study, we systematically investigated the phototransformation behavior and toxicity evolution of two widely used chiral pesticides (triadimefon (TF) and triadimenol (TN)) at enantiomer and diastereomer levels, and proposed a calculation method of total photolysis rate constants of chiral mixture. Results show that TF and TN could be photodegraded faster in pure water than in natural waters, and the observed photolysis rate constants (kobs) of TN with two chiral centers exhibit enantioselectivity, i.e., kobs(TN-RS) = kobs(TN-SR) > kobs(TN-RR) = kobs(TN-SS). The photolysis of TF and TN mainly occurs through their excited singlet and triplet states, respectively. Their photodegradation pathways mainly include dechlorination and elimination of triazole ring. TF could also undergo ether bond cleavage. It is also found that, both TF and TN exhibit photo-induced toxicity to V. fischeri, due to the generation of more toxic products than parent compounds. Furthermore, TN exhibits enantioselective photo-induced toxicity after 240-min irradiation, which could be ascribed to the formation of chiral products. These results could benefit the understanding of enantioselective environmental behavior of chiral pollutants.
Abstract
Background
Postpartum depression (PPD) is considered an important public health problem, and early recognition of PPD in pregnant and lactating women is critical. This study investigated the ...knowledge, attitude, and practice (KAP) toward PPD among pregnant and lying-in women.
Methods
This cross-sectional study was conducted at Binzhou Medical University Hospital between September 2022 and November 2022 and included pregnant and lying-in women as study participants. A questionnaire was designed by the researchers that included demographic data and knowledge, attitude, and practice dimensions. Correlations between knowledge, attitude, and practice scores were evaluated by Pearson correlation analysis. Factors associated with practice scores were identified by multivariable logistic regression.
Results
All participants scored 6.27 ± 2.45, 36.37 ± 4.16, and 38.54 ± 7.93 93 from three sub-dimensions of knowledge, attitudes, and practices regarding PPD, respectively, with statistical differences in the three scores by age, education, and job status (p < 0.05). There were no significant differences between maternal (6.24 ± 2.34, 36.67 ± 3.82 and 38.31 ± 7.27, respectively) and pregnant women (6.30 ± 2.49, 36.00 ± 4.53 and 38.83 ± 8.69, respectively) in the total scores of knowledge, attitude, and practice dimensions. According to the results of multivariate logistic regression, the knowledge (OR = 1.2351.128–1.353, P < 0.001) and attitude (OR = 1.0521.005–1.102, P = 0.030) dimension scores were factors influencing the practice dimension scores.
Conclusion
The KAP of pregnant and lying-in women toward PPD is low. This study suggests that maternal awareness of PPD should be increased through the knowledge and attitudinal dimensions. Preventing PPD in pregnant and lying-in women can be achieved by improving both dimensions, thus enhancing practice.
In this study, an anammox reactor was operated to treat low-strength (NH
+ NO
, 25-35 mg/L) wastewater without (phase I) or with (phase II) readily biodegradable chemical oxygen demand (rbCOD). In ...phase I, although efficient nitrogen removal was achieved at the beginning, nitrate accumulated in the effluent after long-term operation (75 days), resulting in a decrease in the nitrogen removal efficiency to 30%. Microbial analysis revealed that the abundance of anammox bacteria decreased from 2.15 to 1.78%, whereas that of nitrite-oxidizing bacteria (NOB) increased from 0.14 to 0.56%. In phase II, rbCOD, in terms of acetate, was introduced into the reactor with a carbon/nitrogen ratio of 0.9. The nitrate concentration in the effluent decreased within 2 days. Advanced nitrogen removal was achieved in the following operation, with an average effluent total nitrogen of 3.4 mg/L. Despite the introduction of rbCOD, anammox pathway still dominated to the nitrogen loss. High-throughput sequencing indicated that high anammox abundance (2.48%) further supports its dominant position. The improvement in nitrogen removal was attributed to the enhanced suppression of NOB activity, simultaneous nitrate polishing through partial denitrification and anammox, and promotion of sludge granulation. Overall, the introduction of low concentrations of rbCOD is a feasible strategy for achieving robust and efficient nitrogen removal in mainstream anammox reactors.
Conventional biological removal of nitrogen and phosphorus is usually limited due to the lack of biodegradable carbon source, therefore, new methods are needed. In this study, a new alternative ...consisting of enhanced biological phosphorus removal （EBPR） followed by partial nitritation- anammox （PN/A）, is proposed to enhance nutrients removal from municipal wastewater. Research was carried out in a laboratory-scale system of combined two sequencing batch reactors （SBRs）. In SBR1,phosphorus removal was achieved under an altemating anaerobic-aerobic condition and ammonium concentration stayed the same since nitrifiers were washed out from the reactor under short sludge retention time of 2-3 d. The remaining ammonium was further treated in SBR2 where PN/A was established by inoculation. A maximum of nitrogen removal rate of 0.12 kg N. m^-3. d^-1 was finally achieved. During the stable period effluent concentrations of total phosphorus and total nitrogen were 0.25 and 10.8 mg· L ^-, respectively. This study suggests EBPR-PN/A process is feasible to enhance nutrients removal from municipal wastewater of low influent carbon source.
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