7 research outputs found
Molecular Design and Mechanism Analysis of Phthalic Acid Ester Substitutes: Improved Biodegradability in Processes of Sewage Treatment and Soil Remediation
Phthalic acid esters (PAEs) have the characteristics of environmental persistence. Therefore, improving the biodegradability of PAEs is the key to reducing the extent of ecological harm realized. Firstly, the scoring function values of PAEs docking with various degrading enzymes in sewage treatment were calculated. Based on this, a 3D-quantitative structure-activity relationship (3D-QSAR) model for PAE biodegradability was built, and 38 PAE substitutes were created. By predicting the endocrine-disrupting toxicity and functions of PAE substitutes, two types of PAE substitutes that are easily degraded by microorganisms, have low toxicity, and remain functional were successfully screened. Meanwhile, the differences in the mechanism of molecular degradation difference before and after PAE modification were analyzed based on the distribution characteristics of amino acid residues in the molecular docking complex. Finally, the photodegradability and microbial degradability of the PAE substitutes in the soil environment was evaluated. From the 3D-QSAR model design perspective, the modification mechanism of PAE substitutes suitable for sewage treatment and soil environment degradation was analyzed. We aim to improve the biodegradability of PAEs at the source and provide theoretical support for alleviating the environmental hazards of using PAEs
Complete genome sequence of bile-isolated Enterococcus avium strain 352
Abstract Background Enterococcus avium is a Gram-positive pathogenic bacterium belonging to the family Enterobacteriaceae. E. avium can cause bacteremia, peritonitis, and intracranial suppurative infection. However, the mechanism of its pathogenesis and its adaptation to a special niche is still unclear. Results In this study, the E. avium strain 352 was isolated from human bile and whole genome sequencing was performed. The E. avium strain 352 consists of a circular 4,794,392Â bp chromosome as well as an 87,705Â bp plasmid. The GC content of the chromosome is 38.98%. There are 4905 and 99 protein coding sequences in the chromosome and the plasmid, respectively. The genome of the E. avium strain 352 contains number of genes reported to be associated with bile adaption, including bsh, sbcC, mutS, nifI, galU, and hupB. There are also several virulence-associated genes including esp, fss1, fss3, ecbA, bsh, lap, clpC, clpE, and clpP. Conclusions This study demonstrates the presence of various virulence factors of the E. avium strain 352, which has the potential to cause infections. Moreover, the genes involved in bile adaption might contribute to its ability to live in bile. Further comparative genomic studies would help to elucidate the evolution of pathogenesis of E. avium
Polarity Modulation Enhances Electrocatalytic Reduction of Nitrate by Iron Nanocatalysts
Electrocatalytic reduction to convert
nitrate (NO3â) to N2 or NH3 is of great interest
for water and wastewater treatment, as well as N cycle management.
However, the inherent electrostatic repulsion between the negatively
charged nitrate ion and the cathode hinders nitrate adsorption on
the catalyst and decreases reaction kinetics. In this study, we demonstrate
that a simple polarity modulation strategy greatly enhances NO3â reduction catalyzed by an iron nanocatalyst
immobilized on a carbon black electrode (Fe@CB). By switching between
a positive and a negative potential, the system cycled through a short
electrosorption step and a longer electrocatalytic reduction step.
This increases the pseudo-first-order reaction rate constant of nitrate
reduction from 2.46 to 3.09 hâ1, a 25.6% increase
compared to the constant potential operation. The improved nitrate
reduction kinetics was attributed to the enhanced nitrate adsorption
during the electrosorption step, which improved the subsequent electrocatalytic
reduction of NO3â upon reversal of the
applied voltage. A short 30 s adsorption step at +0.1 V was found
to enhance NO3â adsorption while avoiding
reoxidation of reduced species formed in the previous reduction step.
This operational strategy can be easily applied to other electrodes
and catalysts, offering a simple, chemical-free, and cost-effective
method for the removal of NO3â and valorization
Developmental changes in lipid and fatty acid metabolism and the inhibition by in ovo feeding oleic acid in Muscovy duck embryogenesis
Hepatic lipid and fatty acid (FA) metabolism are critical for regulating energetic homeostasis during embryogenesis. At present, it remains unclear how an exogenous FA intervention affects embryonic development in an avian embryo model. In Exp. 1, 30 fertilized eggs were sampled on embryonic days (E) 16, 19, 22, 25, 28, 31 and the day of hatch (DOH) to determine the critical period of lipid metabolism. In Exp. 2, a total of 120 fertilized eggs were divided into two groups (60 eggs/group) for in ovo feeding (IOF) procedures on E25. Eggs were injected into the yolk sac with PBS as the control group and with oleic acid (OA) as the IOF-OA treatment group. Samples were collected on E28 and E31. In Exp. 1, hepatic triacylglycerol (TG) and cholesterol (CHO) contents increased while serum TG content decreased from E16 to DOH (PÂ Â 0.05). Maximal metabolic changes in lipid and FA metabolism occurred on E22-E28 in Muscovy duck embryogenesis, along with the altered target gene and protein expression related to lipogenesis and lipolysis. IOF-OA intervention on E25 could inhibit the target gene expression related to FA uptake, synthesis, and oxidation, which may influence the normal FA metabolism on E28 during embryogenesis
Aqueous-Processed, High-Capacity Electrodes for Membrane Capacitive Deionization
Membrane capacitive deionization
(MCDI) is a low-cost technology
for desalination. Typically, MCDI electrodes are fabricated using
a slurry of nanoparticles in an organic solvent along with polyvinylidene
fluoride (PVDF) polymeric binder. Recent studies of the environmental
impact of CDI have pointed to the organic solvents used in the fabrication
of CDI electrodes as key contributors to the overall environmental
impact of the technology. Here, we report a scalable, aqueous processing
approach to prepare MCDI electrodes using water-soluble polymer polyÂ(vinyl
alcohol) (PVA) as a binder and ion-exchange polymer. Electrodes are
prepared by depositing aqueous slurry of activated carbon and PVA
binder followed by coating with a thin layer of PVA-based cation-
or anion-exchange polymer. When coated with ion-exchange layers, the
PVA-bound electrodes exhibit salt adsorption capacities up to 14.4
mg/g and charge efficiencies up to 86.3%, higher than typically achieved
for activated carbon electrodes with a hydrophobic polymer binder
and ion-exchange membranes (5â13 mg/g). Furthermore, when paired
with low-resistance commercial ion-exchange membranes, salt adsorption
capacities exceed 18 mg/g. Our overall approach demonstrates a simple,
environmentally friendly, cost-effective, and scalable method for
the fabrication of high-capacity MCDI electrodes