Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products

<div><p>The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (<1 kDa) and fewer high-MW compounds (>100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.</p></div

Assessing dissolved organic matter in the Johannesburg-Sulfur autotrophic denitrification system using excitation—emission matrix fluorescence spectroscopy with a parallel factor analysis

<p>A novel system integrating Johannesburg (JHB) and sulfur autotrophic denitrification (SAD) process was proposed with the purpose of efficient removal of organic matter and nitrogen when treating low COD/TN ratio municipal wastewater. The characteristics and fate of dissolved organic matter in the Johannesburg-Sulfur autotrophic denitrification (JHB-SAD) system were investigated using excitation–emission matrix fluorescence spectroscopy with a parallel factor analysis. Three components were identified including tryptophan-like (component <i>C</i>₁), tyrosine-like (component <i>C</i>₂), and fulvic-like (component <i>C</i>₃) materials. The tyrosine-like and tryptophan-like materials, which were more abundant than fulvic-like materials, were the dominant components of the raw municipal wastewater in Shenyang North Wastewater Treatment Plant. In the JHB-SAD system, the tyrosine-like and tryptophan-like materials were more efficiently removed than the fulvic-like materials, and the removal efficiencies of the three components were 80.8% (tryptophan-like materials), 72.5% (tyrosine-like materials), and 33.4% (fulvic-like materials), respectively. Furthermore, the removal performance of the three components varied in the different zones of the JHB-SAD system. The tryptophan-like and fulvic-like materials were removed in the pre-anoxic, anaerobic, and aerobic zones. The tyrosine-like materials were mainly degraded in the anoxic and aerobic zones; then, they were released by the bacteria in the SAD reactor. In addition, the tryptophan-like materials had a very significant positive linear correlation with the concentrations of soluble chemical oxygen demand.</p

Data_Sheet_1_A Polyamine-Based Dinitro-Naphthalimide Conjugate as Substrates for Polyamine Transporters Preferentially Accumulates in Cancer Cells and Minimizes Side Effects in vitro and in vivo.docx

Naphthalimides, such as amonafide and mitonafide in clinical trials, have been developed as antitumor agents for orthotopic tumor. However, the serious side effects in cancer patients limit their applications. Herein, a new class of polyamine-based naphthalimide conjugates 5a-5c, 7a-7b, and 11a-11b with and without the alkylation of the distant nitrogen in the polyamine chain were synthesized and the mechanism was determined. Compared with amonafide, dinitro-naphthalimide conjugate 5c with a 4,3-cyclopropyl motif preferentially accumulates in cancer cells and minimizes side effects in vitro and in vivo. More importantly, 5c at the dosage of as low as 3 mg/kg (57.97%) displays better antitumor effects than the positive control amonafide (53.27%) at 5 mg/kg in vivo. And a remarkably elevated antitumor activity and a reduced toxicity are also observed for 5c at 5 mg/kg (65.90%). The upregulated p53 and the apoptotic cells (73.50%) indicate that the mechanism of 5c to induce apoptosis may result from its enhanced DNA damage. Further investigation indicates that in addition to target DNA, 5c can modulate the polyamine homeostasis by upregulating polyamine oxidase (PAO) in a different way from that of amonafide. And also by targeting PTs overexpressed in most of cancer cells, 5c downregulates the contents of Put, Spd, and Spm, which are in favor of suppressing fast-growing tumor cells. Our study implies a promising strategy for naphthalimide conjugates to treat hepatic carcinoma with notable activities and reduced toxicities at a low dosage.</p