Sulfate Decelerated Ferrous Ion-Activated Persulfate Oxidation of Azo Dye Reactive Brilliant Red: Influence Factors, Mechanisms, and Control Methods

This study investigated the inhibition effects of sulfate on ferrous ion-activated persulfate oxidation of azo dye reactive brilliant red X-3B. The experimental results showed that the degradation efficiency of reactive brilliant red X-3B decreased from 100% to 63% in 60 min when the initial concentration of sulfate increased from 0 to 3 g/L. The ferrous/persulfate molar ratio had remarkable influence on persulfate oxidation capability in presence of sulfate. SO42− could coordinate with Fe2+ and Fe3+ in generating FeSO4 ion pairs as well as FeSO4+ or Fe(SO4)2− complexes, which were difficult to activate persulfate and reduced the regeneration of Fe2+. Radicals quenching and electron paramagnetic resonance experiments showed that ·OH and SO4·− were responsible for the oxidation of reactive brilliant red X-3B; however, the addition of sulfate significantly inhibited the generation of SO4·−, and then the generation of ·OH. Moreover, the corresponding Nernst equation indicated that high concentration of sulfate reduced the oxidation potential of SO4·−/SO42−. Experimental results proved that the adverse effects of sulfate on the persulfate oxidation could be counteracted either by batch addition of ferrous or by adding Ba2+ to remove SO42− in the system

Sulfate Decelerated Ferrous Ion-Activated Persulfate Oxidation of Azo Dye Reactive Brilliant Red: Influence Factors, Mechanisms, and Control Methods

This study investigated the inhibition effects of sulfate on ferrous ion-activated persulfate oxidation of azo dye reactive brilliant red X-3B. The experimental results showed that the degradation efficiency of reactive brilliant red X-3B decreased from 100% to 63% in 60 min when the initial concentration of sulfate increased from 0 to 3 g/L. The ferrous/persulfate molar ratio had remarkable influence on persulfate oxidation capability in presence of sulfate. SO42− could coordinate with Fe2+ and Fe3+ in generating FeSO4 ion pairs as well as FeSO4+ or Fe(SO4)2− complexes, which were difficult to activate persulfate and reduced the regeneration of Fe2+. Radicals quenching and electron paramagnetic resonance experiments showed that ·OH and SO4·− were responsible for the oxidation of reactive brilliant red X-3B; however, the addition of sulfate significantly inhibited the generation of SO4·−, and then the generation of ·OH. Moreover, the corresponding Nernst equation indicated that high concentration of sulfate reduced the oxidation potential of SO4·−/SO42−. Experimental results proved that the adverse effects of sulfate on the persulfate oxidation could be counteracted either by batch addition of ferrous or by adding Ba2+ to remove SO42− in the system

Gene Expression and Chromatin Modifications Associated with Maize Centromeres

Centromeres are defined by the presence of CENH3, a variant of histone H3. Centromeres in most plant species contain exclusively highly repetitive DNA sequences, which has hindered research on structure and function of centromeric chromatin. Several maize centromeres have been nearly completely sequenced, providing a sequence-based platform for genomic and epigenomic research of plant centromeres. Here we report a high resolution map of CENH3 nucleosomes in the maize genome. Although CENH3 nucleosomes are spaced ∼190 bp on average, CENH3 nucleosomes that occupied CentC, a 156-bp centromeric satellite repeat, showed clear positioning aligning with CentC monomers. Maize centromeres contain alternating CENH3-enriched and CENH3-depleted subdomains, which account for 87% and 13% of the centromeres, respectively. A number of annotated genes were identified in the centromeres, including 11 active genes that were located exclusively in CENH3-depleted subdomains. The euchromatic histone modification marks, including H3K4me3, H3K36me3 and H3K9ac, detected in maize centromeres were associated mainly with the active genes. Interestingly, maize centromeres also have lower levels of the heterochromatin histone modification mark H3K27me2 relative to pericentromeric regions. We conclude that neither H3K27me2 nor the three euchromatic histone modifications are likely to serve as functionally important epigenetic marks of centromere identity in maize

Construction of acoustic model and simulation of sound absorption of aero-engine composite acoustic liner

Acoustic liner is an important component to reduce engine noise. In this work, the modal sound source characteristics of the pipeline under different flow fields were calculated and used as the input boundary for the background flow field calculation and sound propagation calculation of the Actran software, thereby establishing the sound propagation model. The influences of four structural parameters on the sound absorption effect of the muffler plate hole diameter, hole spacing, honeycomb height, and muffler plate thickness in the single-DOF acoustic liner and the double-DOF acoustic liner were studied respectively. The simulation results show that both degrees of freedom acoustic liners exhibit the phenomenon that the smaller the perforation diameter, the better the sound absorption performance within a certain range of hole diameter. The effects of hole spacing, honeycomb height, and muffler thickness on the sound absorption performance are varied with frequency, the double-DOF acoustic liner above 2500 Hz has large dissipation power and good sound absorption effect. Through the contrast verification in the flow tube test, the transmission loss of the acoustic liner of different structures under different excitation sources is compared, and a reasonable and credible simulation method is obtained

Responses of Bacterial Communities to CuO Nanoparticles in Activated Sludge System

The main objectives of this study were to investigate the influence of copper oxide nanoparticles (CuO NPs) on wastewater nutrient removal, bacterial community and molecular ecological network in activated sludge. The results showed that long-term exposure to 1 mg/L CuO NPs induced an increase of effluent concentrations of ammonia and total phosphorus, which was consistent with the inhibition of enzyme activities of ammonia monooxygenase, nitrite oxidoreductase, exopolyphosphatase, and polyphosphate in the presence of CuO NPs. MiSeq sequencing data indicated that CuO NPs significantly decreased the bacterial diversity and altered the overall bacterial community structure in activated sludge. Some genera involved in nitrogen and phosphorus removal, such as <i>Nitrosomonas</i>, <i>Acinetobacter</i>, and <i>Pseudomonas</i> decreased significantly. Molecular ecological network analysis showed that network interactions among different phylogenetic populations were markedly changed by CuO NPs. For example, β-<i>Proteobacteria</i>, playing an important role in nutrients removal, had less complex interactions in the presence of CuO NPs. These shifts of the abundance of related genera, together with the network interactions may be associated with the deterioration of ammonia and phosphorus removal. This study provides insights into our understanding of shifts in the bacteria community and their molecular ecological network under CuO NPs in activated sludge systems

Vacuolar Invertase Gene Silencing in Potato (<i>Solanum tuberosum</i> L.) Improves Processing Quality by Decreasing the Frequency of Sugar-End Defects

<div><p>Sugar-end defect is a tuber quality disorder and persistent problem for the French fry processing industry that causes unacceptable darkening of one end of French fries. This defect appears when environmental stress during tuber growth increases post-harvest vacuolar acid invertase activity at one end of the tuber. Reducing sugars produced by invertase form dark-colored Maillard reaction products during frying. Acrylamide is another Maillard reaction product formed from reducing sugars and acrylamide consumption has raised health concerns worldwide. Vacuolar invertase gene (<i>VInv</i>) expression was suppressed in cultivars Russet Burbank and Ranger Russet using RNA interference to determine if this approach could control sugar-end defect formation. Acid invertase activity and reducing sugar content decreased at both ends of tubers. Sugar-end defects and acrylamide in fried potato strips were strongly reduced in multiple transgenic potato lines. Thus vacuolar invertase silencing can minimize a long-standing French fry quality problem while providing consumers with attractive products that reduce health concerns related to dietary acrylamide.</p></div

Kinetics of Polymer Desorption from Colloids Probed by Aggregation-Induced Emission Fluorophore

Polymer adsorption and desorption are fundamental in many industrial and biomedical applications. Here, we introduce a new method to monitor the polymer desorption kinetics in situ based on the behavior of aggregation-induced emission. Poly­(ethylene oxide) and colloidal silica (SiO₂) were used as a model system. It was found that the aggregation-induced emission method could be successfully used to determine the polymer desorption kinetics, and the polymer desorption followed the first-order kinetics. It was also found that the polymer desorption rate constant decreased with the increasing molecular weight, which could be described by a power law function <i>k</i>_d ≈ <i>M</i>^–0.28, close to that of the adsorption rate constant

Time and position dependent <i>VInv</i> expression and acid invertase activity in Russet Burbank silencing lines differed from that in Russet Burbank controls.

<p><i>VInv</i> expression (A, C) and acid invertase activity (B, D) in the stem (A, B) and bud (C, D) end of five <i>VInv</i>-silencing lines and controls of Russet Burbank potato tubers at harvest and after 1, 3 and 5 months of storage. <i>VInv</i> expression in stem and bud end samples was expressed relative to expression of the reference gene <i>actin97</i>. Bars represent mean ± standard error of five independent tuber samples.</p

<i>VInv</i> mRNA abundance and acid invertase activity were reduced in tubers of Ranger Russet with <i>VInv</i>-silencing compared with tubers of Ranger Russet controls.

<p><i>VInv</i> expression (A) and acid invertase activity (B) in both tuber ends of RNAi lines 1632-1, 1632-3, and 1632-5 and Ranger Russet control tubers. <i>VInv</i> expression relative to expression of the reference gene <i>actin97</i> was determined for stem and bud end tuber samples. Expression data are presented as a percentage of <i>VInv</i> expression in tuber bud end samples of Ranger Russet controls. Bars represent mean ± standard error of five independent tuber samples.</p