Aqueous chromium(VI) reduction and removal induced by glow discharge taking place at the gas–solution interface in an argon atmosphere was studied. The effect of initial pH and hydroxyl radical ...scavenger (ethanol) on the reduction efficiency was examined. High reduction efficiency was obtained when initial pH ≤ 2.0 or ≥ 8.0. In particular, addition of ethanol into the solution substantially increased the reduction efficiency and facilitated chromium removal from the solution in the form of sediment after discharge. The optimum pH values for Cr(VI) removal were within 6.0–7.0. Fourier transform-infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis confirmed that the main constituent of the sediment is chromium hydroxide.
•We propose a new way to treat Microcystic aeruginosa in water via plasma oxidation.•Our approach can inactivate algal cells and degrade microcystins simultaneously.•The mechanism is mainly due to ...the attack of ROS on the cells and the toxins.•Poly-synchronous tools, e.g., EEM and FCM were employed to analyze the processes.
We proposed a method to inactivate M. aeruginosa by using discharge plasma taking at the gas-solution interface supplied by DC power. Multiple analysis techniques including fluorescence excitation–emission matrix (EEM) and flow cytometry (FCM) were used to reveal the inactivation mechanism of M. aeruginosa. The photosynthetic pigment contents including phycocyanin, chlorophyll and metabolites were examined quantitatively. The DC glow discharge plasma caused an increased level of reactive oxygen species (ROS), and the damage of M. aeruginosa cells are mainly attributed to the oxidative stress including OH attack and H2O2 oxidation. Our findings demonstrate that plasma oxidation is a promising technology for inactivation of M. aeruginosa cells with simultaneous removal of microcystins and so it may lead us to a new route to efficient treatment of cyanobacterial blooms.
Microcystin-LR (MC-LR) is one of the most commonly found microcystins (MCs) in fresh water and it poses danger to human health due to its potential hepatotoxicity. In the present study, we employed a ...novel method by using discharge plasma taking place at the gas–solution interface in gas atmosphere to degrade MC-LR in aqueous solution. The initial degradation rate of MC-LR was fastest under acidic conditions (5.41 ± 0.17 × 10−3 mM min−1 at pH 3.04) and decreased to 2.22 ± 0.11 × 10−3 mM min−1 and 0.912 ± 0.02 × 10−3 mM min−1 at pH 4.99 and 7.02, respectively. The effects of total soluble nitrogen (TN), total soluble phosphorus (TP) and natural organic matter (NOM) on the degradation efficiency were studied. The degradation rate was remarkably affected by TP and TN. Mass spectrometry was applied to identify the products of the reactions. Major degradation pathways are proposed according to the results of liquid chromatography/mass spectrometry (LC/MS) results. It suggests that the degradation of MC-LR is initiated via the attack of hydroxyl radicals on the conjugated carbon double bonds of Adda and on the benzene ring of Adda. Finally, the toxicity of intermediates or end-products from MC-LR degraded by this method was assessed using Caenorhabditis elegans. Our findings demonstrates that discharge plasma oxidation is a promising technology for degradation and removal of MC-LR and it may lead us to a new route to efficient treatment of other cyanotoxins from aqueous solutions.
Display omitted
► We designed a novel device to degrade microcystin-LR effectively via discharge plasma oxidation. ► The effects of pH value, TN, TP and NOM on the discharge plasma degradation efficiency were examed. ► The mechanism is mainly due to attack of hydroxyl radicals on the conjugated carbon double bonds. ► The toxicity was evaluated by C. elegans survival test which proves the safety of the treatment.
A novel approach to prepare activated carbon from blue-green algal bloom residue has been tried for first time and its adsorption capability to remove hexavalent chromium Cr(VI) from aqueous solution ...has been examined. For this algal bloom residue derived activated carbon, the physical characters regarding adsorption capability were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and Fourier transform infrared (FTIR) spectroscopy. Batch studies showed that initial pH, absorbent dosage, and initial concentration of Cr(VI) were important parameters for Cr(VI) absorption. It was found that initial pH of 1.0 was most favorable for Cr(VI) removal. The adsorption process followed the pseudo-second-order equation and Freundlich isotherm. The maximum adsorption capacity for Cr(VI) was 155.52
mg
g
−1 in an acidic medium, which is comparable to best result from activated carbons derived from biomass. Therefore, this work put forward a nearly perfect solution which on one hand gets rid of environment-unfriendly algae residue while on the other hand produces high-quality activated carbon that is in return advantageous to environment protection.
The discovery of bio-effects by implantation of low-energy ions into biological organisms has opened a new branch in the field of ion beam application in life sciences. The groundwork of this area is ...based on the hypothesis of a combination of energy absorption, mass deposition, and charge transfer of energetic ions in the organisms, resulting in damage and inducing mutation effects. Although mechanism studies of the interaction between low-energy ions and organisms have made progress, ion beam applications in biotechnology have attained more achievements than the study of the interaction mechanisms.
The C-terminus region of endo-β-glucanase Egl499 from
Bacillus subtilis JA18 was suggested to be a putative family 3 cellulose-binding domain (CBD) by computer analysis. To prove this proposal, ...C-terminus truncation mutant Egl330 was constructed and expressed. Compared with Egl499, Egl330 lost the cellulose binding capability at 4
°C, confirming the C-terminus region was a CBD. Binding of the CBD to Avicel was inhibited by carboxymethylcellulose (CMC), but not by barley β-glucan and glucose at concentration of 0.1% and 0.5%. Kinetic analysis showed both the turnover rate (
k
cat) and the catalytic efficiency (
k
cat/
K
m) of Egl330 increased for the substrate CMC compared to Egl499. A great improvement in thermal stability was observed in Egl330. The half life of Egl330 at 65
°C increased to three folds that of Egl499, from 10 to 29
min. After treated at 80
°C for 10
min, Egl330 could recover more than 60% of its original activity while Egl499 only recovered 12% activity. UV spectrometry analysis showed Egl330 and Egl499 differed in refolding efficiency after heat treatment.
Botrytis cinerea is one of the most serious post-harvest pathogens of fruits and vegetables. Volatiles generated by Bacillus subtilis JA significantly inhibited both spore germination and elongation ...of germ tubes in Botrytis cinerea using a two-compartment agar-plate assay. The volatiles caused protoplasm retraction from the hyphal tips to the spores.
Although non‐thermal discharge plasma is more and more applied in biological field, the molecular mechanisms of plasma acting on biomolecules are still unclear, which are indispensable for ...understanding the plasma‐induced biological effects. In this work, discharge plasma at the gas–solution interface was employed to irradiate on reduced glutathione (GSH), the most abundant low molecular weight thiol‐containing antioxidant in cells. Through Raman spectroscopy, both the irreversible damage and reversible conversion of GSH to oxidized glutathione (GSSG) were monitored in a non‐destructive fashion, so that the reaction kinetic processes through multi‐pathways could be evaluated quickly and quantitatively. Based on the experimental data, the reaction mechanism was discussed.
Both irreversible damage and reversible conversion of reduced glutathione to oxidized form induced by discharge plasma at the gas–solution interface is quantitatively detected by using Raman spectroscopy.
The radiation-induced bystander effect is defined as "the induction of biological effects in cells that are not directly traversed by a charged particle but are in close proximity to cells that are." ...Although these bystander effects have been demonstrated with a variety of biological endpoints in both human and rodent cell lines (as well as in 3D tissue samples), the mechanism of the phenomenon is not known. Although gap junction communication and the presence of soluble mediator(s) are both known to play important roles in the bystander response, the precise signaling molecules have yet to be identified. By using the Columbia University charged particle beam in conjunction with a strip dish design, we show here that the cyclooxygenase-2 (COX-2, also known as prostaglandin endoperoxide synthase-2) signaling cascade plays an essential role in the bystander process. Treatment of bystander cells with NS-398, which suppresses COX-2 activity, significantly reduced the bystander effect. Because the critical event of the COX-2 signaling is the activation of the mitogen-activated protein kinase pathways, our finding that inhibition of the extracellular signal-related kinase phosphorylation suppressed bystander response further confirmed the important role of mitogen-activated protein kinase signaling cascade in the bystander process. These results provide evidence that the COX-2-related pathway, which is essential in mediating cellular inflammatory response, is the critical signaling link for the bystander phenomenon.
A novel approach to prepare adsorbent from pine tree root decayed by brown-rot fungi (BRW) has been tried for the first time to remove malachite green (MG) from aqueous solutions. The adsorption ...capacity of MG was increased 19.45% compared with the pine sawdust. The adsorption capacity was studied by varying the parameters such as initial dye concentration, adsorbent dose, temperature and pH value. Optimal adsorption capacity (42.63
mg/g) and rate (99.41%) was obtained at near neutral pH. Characterization of the biosorbent was performed using scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and Fourier transform-infrared (FTIR) spectroscopy. The kinetic and equilibrium studies suggest that the adsorption follows Langmuir isotherm and the pseudo-second-order model. Together with the evaluation of the thermodynamic parameters such as Gibb's free energy, enthalpy and entropy, our results showed that MG adsorption onto BRW was mainly a spontaneous, endothermic and chemisorption process.
► A novel way of preparing biosorbent: pine wood decayed by fungi
Poria cocos. ► Adsorb malachite green very effectively: up to 99.41% under the optimal conditions. ► Easy, cheap and practical: costs only ca. $6/100
kg in China. ► Detailed in equilibrium, kinetic and thermodynamic analysis.
PDF
