•Pseudomonas sp. exhibited the HN-AD ability using PCL as a sole carbon source.•The amoA, napA, nirS, cnorB and nosZ genes were successfully expressed.•The weight loss of PCL films reached 94.03% ...after 60-days degradation.•The increase in PCL concentrations led to a decrease in nitrogen removal rate.
The novel isolated strain JQ-H3 exhibited heterotrophic nitrification-aerobic denitrification (HN-AD) ability using poly (ε-caprolactone) (PCL) as a sole carbon source under aerobic conditions. This was the first time that a PCL-degrading bacterium was characterized to be with capability of nitrifying and denitrifying performances. Strain JQ-H3 removed approximately 95.40% of NH4+-N (102.40 mg/L), about 91.1% of NO3−-N (99.01 mg/L), with the maximum specific removal rates of 0.308 mg NH4+-N/mg DCW/h and 0.220 mg NO3−-N/mg DCW/h, respectively. The functional genes amoA, napA, nirS, cnorB, and nosZ were successfully expressed during the nitrogen removal process. An increasing PCL concentrations caused a decline in cell growth and nitrogen removal efficiency, which was attributed to the decrease in the rate of the PCL hydrolysis and the amount of dissolved organic carbon (DOC) release. These results demonstrated the strain as an ideal candidate for nitrogen removal from wastewater by using PCL as carbon source.
•Persulfate activation in discharge plasma for tetracycline (TC) removal was studied.•Persulfate added in discharge plasma improved degradation efficiency and rate of TC.•Enhanced removal of TC was ...attributed to increment of SO4− and OH.•Possible degradation pathway assumed for TC in synergistic system was given.
A process of persulfate (PS) activation in gas phase surface discharge plasma was studied to facilitate the removal of tetracycline (TC) in water. PS was introduced into the discharge reactor, and the effects of PS added dosage and applied voltage on TC removal were determined. The results showed that PS addition exhibited significant synergistic effect, promoting the degradation efficiency and removal rate of TC. Increasing the applied voltage was beneficial to the enhancement of TC decomposition. The removal efficiency and first order kinetic constant were achieved 87.5% and 0.232 min−1 at a PS addition dosage of 20:1 (molar ratio of PS to TC) and a discharge voltage of 7 kV after 15 min treatment, respectively. Especially the calculated synergistic factor achieved 1.856, indicating the synergistic effect was existed. Besides, the removal of the synergistic system was influenced remarkably by the other operation parameters, including air flow rate, initial TC concentration, and initial pH value. The mineralization of TC and intermediates produced during the synergistic process was explored by UV–vis spectrogram and TOC analyses. The synergistic effect could be explained by the enhanced formation of hydroxyl and sulfate radicals that were generated from the activation of PS in discharge plasma. The evolution of the main degradation byproducts in the synergism process was investigated by HPLC–MS.
During the second and third year after birth the gut microbiota (GM) is subjected to important development. The polycyclic aromatic hydrocarbon (PAH) exposure could influence the GM in animal and ...early postnatal exposure is associated with neurodevelopment disorder in children. This study was designed to explore the possible influence of the polycyclic aromatic hydrocarbons (PAHs) on the composition of the gut microbiota (GM) and neurodevelopment in a sample of 38 healthy children at the age of 3 years.
A brief development (Gesell Development Inventory, GDI) and behavior test (Child Behavior Checklist, CBCL) were completed on 3-yr-olds and stool samples were collected for 16S rRNA V4-V5 sequencing. The PAH-DNA adduct in the umbilical cord blood and the urinary hydroxyl PAHs (OH-PAHs) at the age of 12 months were measured as pre- and postnatal PAH exposure, respectively.
The most abundant two phyla were Bacteroidetes (68.6%) and Firmicutes (24.2%). The phyla Firmicutes, Actinobacteria, Proteobacteria, Tenericutes, and Lentisphaerae were positively correlated with most domain behaviors of the GDI, whereas the Bacteroidetes, Cyanobacteria, and Fusobacteria were negatively correlated. Correspondingly, the phyla Bacteroidetes, Actinobacteria, and Fusobacteria showed positive correlations with most CBCL core and broadband syndromes, whereas the Firmicutes, Verrucomicrobia, Synergistetes, Proteobacteria and Tenericules were negatively correlated. The OH-PAH levels were not significantly associated with the Firmicutes phylum whereas the Bacteroidetes, Bacteroidia, and Bacteroidales all showed significant negative association with the OH-PAH levels.
The current findings suggest that composition of the GM is associated with neurodevelopment of the child. PAHs seem to change the relative abundance of some taxa (some deleted and some recruited) to counteract the negative effects of the PAHs.
Malate accumulation has been suggested to balance Al-induced citrate synthesis and efflux in soybean roots. To test this hypothesis, characteristics of Al-induced accumulation and efflux of citrate ...and malate were compared between two soybean genotypes combining a functional analysis of
putatively encode a cytosolic NADP-malic enzyme. Similar amounts of citrate were released, and root elongation was equally inhibited before 8 h of Al treatment of Jiyu 70 and Jiyu 62 cultivars. Jiyu 70 began to secrete more citrate and exhibited higher Al resistance than did Jiyu 62 at 12 h. A sustained increase in internal malate and citrate concentrations was observed in Jiyu 70 at 24 h of Al treatment. However, Jiyu 62 decreased its malate concentration at 12 h and its citrate concentration at 24 h of Al treatment. GmME1 localized to the cytoplast and clustered closely with cytosolic malic enzymes AtME2 and SgME1 and was constitutively expressed in the roots. Al treatment induced higher NADP-malic enzyme activities and
expression levels in Jiyu 70 than in Jiyu 62 within 24 h. Compared with wild-type hairy roots, over-expressing
in hairy roots (
-OE) produced higher expression levels of
but did not change the expression patterns of either of the putative citrate transporter genes
and
or the malate transporter gene
, with or without Al treatment.
-OE showed a higher internal concentration and external efflux of both citrate and malate at 4 h of Al stress. Lighter hematoxylin staining and lower Al contents in root apices of
-OE hairy roots indicated greater Al resistance. Comprehensive experimental results suggest that sustaining Al-induced citrate efflux depends on the malate pool in soybean root apices.
encodes a cytosolic malic enzyme that contributes to increased internal malate and citrate concentrations and their external efflux to confer higher Al resistance.
Abstract
Tunnel construction in karst strata with abundant water causes changes in the surrounding groundwater environment, which can easily trigger geological disasters such as mud and water inrush. ...How to accurately predict the groundwater ahead of tunnel excavation face is a highly challenging problem. In order to improve the detection accuracy of groundwater during the construction of a deep buried tunnel, the transmission and reflection process of seismic waves at the interface and the relationship between the reflection coefficient and seismic wave signal have been analyzed on the basis of a two-phase medium theory in this paper. The expression of seismic wave stress–response relationship associated with the instantaneous amplitude and instantaneous phase and frequency is established. Then the relationship between seismic wave attributes and groundwater seepage potential energy is derived by combining the fluid mechanics theory, which is used as the basis for the determination and identification of groundwater volume and classified, and a new technology of an advanced detection of groundwater by seismic waves is established. This method has been applied to the Zhanghuai Railway in China and quantitatively predicted the karst water and caves in the Tianqiaoshan Tunnel before excavation. The engineering test proves the reliability and advancement of this technology.
A denitrifying strain ZY04 with a high nitrite-accumulating rate was isolated and purified from activated sludge in a laboratory-scale A
/O reactor. The strain was characterized and identified as
by ...16S rDNA phylogenetic analysis. The sequences of the key functional genes (
,
,
) involved in partial denitrification were amplified via polymerase chain reaction, which provided a basis for exploring gene expression. The effects of different environmental factors (C/N ratio, pH and temperature) on the partial denitrification performance and transcriptional levels of the functional genes during the logarithmic growth phase were investigated by batch experiments. The results showed that the partial denitrification performance was optimal when the C/N ratio was 5, the pH value was 6-8 and the temperature was 25°C. The gene expression during the logarithmic growth phase indicated the good performance of partial denitrification under different environmental conditions. All three functional genes exhibited the highest expression levels at 25°C. The results of inhibitory kinetics analysis revealed that three biokinetic models (Aiba, Edwards and Andrews) simulated the growth pattern of strain ZY04 inhibited by a single substrate (nitrate or sodium acetate) well. In the double-substrate inhibitory model, five models of nine combinations successfully fitted the growth characteristics of the strain affected by the double substrate of nitrate and sodium acetate. The relevant semi-saturation parameters and substrate inhibition parameters were obtained, and the correlation coefficient (
) reached 98%.
To assess the safety and effectiveness of percutaneous endoscopic lumbar discectomy (PELD) under epidural anesthesia (EA) and general anesthesia (GA) for treating lumbar disc herniation (LDH).
A ...retrospective study involving 86 patients with LDH managed by PELD under EA and GA was conducted from July 2018 to March 2019. These patients were divided into 2 groups according to the type of anesthesia. Patient's demographics data as well as the operation time, complications, fluoroscopy shots, visual analog scale (VAS), Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA), and MacNab scores of the 2 groups were recorded. All of the patients were followed-up at 6 months after operation.
There were no significant differences were detected in the preoperative demographics between the groups (p > 0.05). Two cases (4.8%) under GA developed transient motor weakness, 3 cases (7.4%) presented numbness of lower limb, and 1 case (2.4%) had cauda equina syndrome after operation. In EA group, 1 case (2.2%) had motor weakness and 3 cases (6.7%) had lower limb numbness, which resolved completely at the last follow-up. There was significant difference between preoperative VAS, JOA, and ODI scores and postoperative scores (p < 0.01). Moreover, there were no differences in the operation time, fluoroscopy shots, and MacNab scores between the 2 groups (p > 0.05).
EA and GA in PELD are effective and safe, and no significant difference in complications was observed. Based on our experience, we recommended junior surgeons to perform PELD under EA for getting feedback from the patient to avoid nerve injury and reduce the radiation dose. The concentration of ropivacaine in EA should be considered carefully.
To investigate the fatigue performance of an orthotropic steel deck (OSD11OSD: orthotropic steel deck; FEA: finite element analysis; LEFM: linear elastic fracture mechanics) in a long-span highway ...suspension bridge with a wide steel-box girder, a finite element analysis (FEA) and a model test were conducted. The fatigue stress characteristics and stress-influence surface of typical fatigue details of the OSD were investigated. An equivalent full-scale fatigue test model with eight U-ribs was tested under five million load cycles. The nominal-stress method and linear elastic fracture mechanics (LEFM) were employed to evaluate the fatigue performance of the OSD. The results demonstrate that the fatigue details near the hanger side have relatively large stresses. The stresses of symmetrical details in one U-rib are in the opposite compression and tension states due to deflection of the wide diaphragm, which is unfavourable for fatigue performance. The stress-influenced surfaces indicate the different multi-vehicle effects for fatigue details. The measured tension stresses near the rib-to-deck welds and rib-to-diaphragm connections changed significantly at 2.25 and 3.0 million cycles, respectively. After 5 million cycles, the measured crack lengths in these details were 130 and 45 mm, respectively. The model's overall deformation performance is hardly affected by the fatigue cracks. According to the damage-accumulation principle, the assessment of the fatigue lives of rib-to-deck and rib-to-diaphragm details were 92.3 and 114.2 years, respectively. The existing recommended fatigue design class would clearly overestimate the fatigue life of rib-to-deck details of the OSD in a wide steel-box girder. According to the LEFM, these fatigue lives were 98.6 and 138.7 years, respectively.
Display omitted
•FEA and full-scale model test conducted to explore the fatigue performance of orthotropic steel deck in a wide box girder•Stresses of symmetrical details in one U-rib are in opposite compress and tension states due to deflection of the diaphragm•Fatigue lives of rib-to-deck were 92.3 and 98.6 years by S-N curve and LEFM•Existing fatigue design class would overestimate the fatigue life of the rib-to-deck details of OSD in a wide box girder
Struvite crystallization is a chemicophysical process for nitrogen and phosphorus recovery, and its product can be used as a slow-release fertilizer. Heavy metals (mainly Cu and Zn) present in swine ...wastewater not only affect the crystallization kinetics, but also increase the product’s ecological risk and make it inadequate for agricultural applications. However, there is currently little research focusing on heavy metal minimization during struvite recovery. This paper is to develop a cost-effective operation strategy, in which minimum process modification and optimum phosphorus recovery could be achieved. The results indicated that the Cu and Zn co-precipitation was mainly controlled by the chemical reaction rather than adsorption during struvite crystallization, making the pre-removal of heavy metals possible. Increasing the ammonia nitrogen concentration could effectively inhibit the co-precipitation of Cu and Zn. When struvite crystallization was performed in synthetic swine wastewater, it was found that the pre-removal of Cu/Zn by chemical precipitation, followed by the increase in initial solution pH, could markedly reduce the Cu and Zn co-precipitation and their contents in the recovered struvite. A pilot-scale test validated such a recommendation. Compared to the conventional struvite crystallization process, the proposed approach could reduce 43.5% Cu and 77.6% Zn in the recovered struvite.
Karst and groundwater are major geological disasters that can easily occur during tunnel construction. How to accurately predict and detect the groundwater and caves during tunnel construction in ...karst strata is a very challenging problem. In this regard, there are few effective detection methods in the literature. Based on the theory of seismic wave propagation dynamics, we proposed a new method to evaluate the seismic wave stress response of the reflection interface in order to detect the existence of karst in the Zhangjihuai railway tunnel. The stress gradient characterizing the pore state formula of rock mass was obtained, and the relationship between the stress gradient and the evaluation value of groundwater was established based on the two-phase media wave and fluid mechanics theories. A 3D seismic wave field observation system and detection method suitable for the tunnel construction environment was proposed and a field study was carried out. The test results verified the effectiveness of the new method in detecting karst and groundwater, and a hydrogeological identification method for karst cave was proposed. The characteristics of the water-free cavity were
d
σ
≥10 and
ν
<20%, and the characteristics of water-filled cavity were
d
σ
≥ 10 and
ν
> 40%.
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