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Impacts of dissolved oxygen (DO) and initial sludge concentrations on aerobic digestion for sewage sludge treatment were studied without adding alkalis. The MLVSS removal efficiencies were 50% and 47% in 20 days when DO concentrations were about 5.0 and 7.0 mg/L, respectively. Value of pH increased slightly in the first 6 days and then dropped constantly. The decrease of MLVSS appeared first quick back slow trend during the process and the OUR declination was similar. At the same DO level of 5.0 mg/L, the lower initial sludge concentration favored the efficiency of sludge stabilization. Both TN and TP of the supernatant were continually increasing and the ultimate concentrations were three to four times the initial concentrations. Results obtained from the present work could provide basic information for the aerobic sludge treatment process.
INTRODUCTION: Complete spinal cord transection (SCT) disturbs the balance between inhibitory and excitatory inputs to motoneurons increasing their excitability. However SCT causes deficiency in excitatory cholinergic input to ankle extensor motoneurons, whereas brain-derived neurotrophic factor (BDNF) overexpression below the lesion site increases markers of spinal neurotransmission and improves locomotor performance. Because glutamatergic receptors (AMPAR, NMDAR) and muscarinic acetylcholine receptor M2 play a crucial role in motoneuron excitability, we investigated if SCT and BDNF affect their expression. AIM(S): To disclose the impact of SCT and BDNF overexpression on levels of AMPAR, NMDAR and M2 mRNA transcripts 2 weeks after SCT. METHOD(S): Total RNA was isolated from L1-2 and L3-6 spinal fragments after SCT followed by intraspinal injection of PBS (n=6) or AAV-BDNF (n=7). After cDNA transcription, AMPAR (subunits GluR1, GluR2), NMDAR (subunits NR1, NR2A, NR2B), and M2 expression were measured using qRT PCR. RESULTS: In intact rats, GluR2 mRNA level was the highest, followed by NR2A/2B, while NR1 and M2 were the lowest. SCT tended to reduce levels of all mRNA transcripts, except for NR1 which tended to increase in L3-6. BDNF overexpression resulted in a significant increase of NR1 and tendency to increase of NR2A in both spinal fragments, while it led to a significant decrease of M2 in L1-2. CONCLUSIONS: BDNF overexpression slightly upregulated mRNA levels of NMDAR after SCT, not preventing deficits of M2. If M2 mRNA decrease is reflected by M2 protein levels in motoneurons, reduced contribution of M2 in modulation of motoneuron excitability may be postulated. FINANCIAL SUPPORT: 665735-Bio4Med-H2020-MSCA--COFUND-2014; National Science Centre 2013/09/B/ NZ4/03306, statutory for the Nencki Institute. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska‑Curie grant agreement No 665735.
INTRODUCTION: Perineuronal nets (PNNs), which restrict axonal regeneration in the glial scar and limit synaptic plasticity, are composed of chondroitin sulfate proteoglycans (CSPGs) and Crtl1/Hapln1 link protein essential for PNN formation. Spinal cord transection (SCT) leads to changes of various CSPG proteins differently distributed between 2nd– 8th postlesion weeks. This raises the question if shortly after SCT when glial scar is formed, processes induced by tissue damage alter expression of genes coding for these proteins. AIM(S): To characterize gene expression levels of the selected CSPGs (brevican, neurocan, aggrecan, phosphacan), and of Crtl1/Hapln1 in the spinal cord of the intact rats and to quantify their changes at the second week after SCT at low-thoracic segments. METHOD(S): The CSPGs and Crtl1/Hapln1 gene transcripts were quantified in rats after complete SCT in fragments of the spinal cord: Th 9/10 (lesion site), its vicinity and in L1–L2. To quantify gene expression qRT-PCR was carried out and expression levels were presented relative to internal control gene (GAPDH) as the CT. RESULTS: In intact rats mRNA level of brevican was the highest among all tested CSPGs and Crtl1/Hapln1. Its level exceeded that of neurocan by 5-fold and the rest of CSPGs by at least 10‑fold. SCT caused significant, 4‑fold increase of neurocan and 5-fold decrease of Hapln1 transcripts in the lesion site, comparing to controls, and did not affect phosphacan and brevican transcripts. SCT caused weaker effects in L1–L2 segments where only neurocan and brevican transcripts significantly increased (by 160% and 30% respectively) whereas Crtl1/Hapln‑1 decreased by 40%. CONCLUSIONS: Increased transcript levels of neurocan in the lesion site indicate stimulation of its gene expression in astrocytes. A decrease in Crtl1/Hapln1 transcript may point to potential disturbances in postlesion PNN formation. FINANCIAL SUPPORT: NCN 2013/09/B/NZ4/03306, Preludium (K.G.) and Statutory for the Nencki Institute.
MLSS and SRT are key parameters in process control. A full-scale modified A2/O process varying with MLSS and SRT was evaluated, and MLSS and SRT effect was distinguished by statistical methods so as to seek early diagnosis and efficient control. Results showed that complete SRT rather than MLSS resulted in considerable effluent SS fluctuation with inert SS accumulation. COD removal was more sensitive to MLSS than SRT. Increasing MLSS until 2,000 mg/L could improve COD, SS, and NH3 removal efficiency, and further increases in MLSS simply enhance stability. MLSS of 2,000 mg/L was also efficient in TP removal. SRT shorter than 30 d was the guarantee for PAOs, while SRT longer than 90 d was equal to complete SRT as TP was removed by assimilation. Prolonged SRT from 30 to 90 days reduced the Yobs from 0.17 to 0.15 g MLSS/g COD. MLSS and SRT had no effect on TN removal. Correlation between MLSS and influent was effective for diagnosing longer SRT. MLSS/RSS could be an indicator for TP removal. The suggested control strategy was SRT-assisted MLSS control.
Starch and sodium carboxymethyl cellulose-coated Fe and Fe /Ni nanoparticles were synthesized and their Cr (VI) removal capabilities were evaluated and compared. We found that starch and sodium carboxymethyl cellulose-coated nanoscale zero-valent iron-nickel (SS-nZVI-Ni) showed the better Cr (VI) removal performance. The effect of acidic conditions on Cr(VI) removal by SS-Nzvi-Ni revealed that the Cr (VI) removal efficiency by SS-nZVI-Ni reached the maximum of 95.70% at pH = 2. The effect of different initial Cr (VI) concentrations showed that SS-nZVI-Ni performed well at a high Cr(VI) concentration. Langmuir-Hinshelwood first-order kinetic model could describe the reduction process well. SEM images revealed that SS-nZVI-Ni had a large surface area, which discarded the problem of aggregation. XRD and XPS analysis of SS-nZVI-Ni showed that SS-nZVI-Ni and Cr (III) formed an alloy on the surface of SS-nZVI-Ni after the reaction. The study provides an option for practical application of SS-nZVI-Ni in Cr (VI) removal.
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