Unraveling the Role of Humic Acid in the Oxidation of Phenolic Contaminants by Soluble Manganese Oxo-Anions.

Humic acid (HA) is ubiquitous in natural aquatic environments and effectively accelerates decontamination by permanganate (Mn(VII)). However, the detailed mechanism remains uncertain. Herein, the intrinsic mechanisms of HA's impact on phenolics oxidation by Mn(VII) and its intermediate manganese oxo-anions were systematically studied. Results suggested that HA facilitated the transfer of a single electron from Mn(VII), resulting in the sequential formation of Mn(VI) and Mn(V). The formed Mn(V) was further reduced to Mn(III) through a double electron transfer process by HA. Mn(III) was responsible for the HA-boosted oxidation as the active species attacking pollutants, while Mn(VI) and Mn(V) tended to act as intermediate species due to their own instability. In addition, HA could serve as a stabilizer to form a complex with produced Mn(III) and retard the disproportionation of Mn(III). Notably, manganese oxo-anions did not mineralize HA but essentially changed its composition. According to the results of Fourier-transform ion cyclotron resonance mass spectrometry and the second derivative analysis of Fourier-transform infrared spectroscopy, we found that manganese oxo-anions triggered the decomposition of C-H bonds on HA and subsequently produced oxygen-containing functional groups (i.e., C-O). This study might shed new light on the HA/manganese oxo-anion process.

Sirtuin 3 (SIRT3) improves sevoflurane-induced postoperative cognitive impairment by regulating mitochondrial oxidative stress.

One of the most prevalent co-operative disorders is postoperative cognitive dysfunction (POCD), however, its pathogenesis remains unclear. Thus, the aim of this work was to evaluate SIRT3's impact on cognitive decline in aged mice under anesthesia. Adeno-associated virus SIRT3 vector (AAV-SIRT3) or empty vector (AAV-VEH) was injected into the hippocampal region of aged mice after sevoflurane induction in order to upregulate the expression of SIRT3. The expression levels of SIRT3, pro-inflammatory cytokines, and apoptotic factors in hippocampus tissues were identified by PCR, Western blotting, TUNEL staining, and enzyme-linked immunosorbent assay (ELISA), and the cognitive function of mice was assessed. The SIRT3 expression was down-regulated in the hippocampal tissue of anesthetized mice. SIRT3 overexpression can improve the learning and memory ability, reduce the escape latency, and increase the residence time in the platform and platform crossing ability of mice. The overexpression of SIRT3 in hippocampus can reduce the oxidative stress response and inflammatory response induced by anesthesia in mice, increase the superoxide dismutase (SOD) expression level, and decrease the expression level of MDA and inflammatory factors in hippocampus. In addition, SIRT3 overexpression can also reduce anesthetic-induced hippocampal cell apoptosis. By reducing the hippocampus mitochondrial oxidative stress response, SIRT3 plays a significant role in the pathophysiology of POCD in mice and is a potential target for POCD treatment and diagnosis.

Count-Based Morgan Fingerprint: A More Efficient and Interpretable Molecular Representation in Developing Machine Learning-Based Predictive Regression Models for Water Contaminants' Activities and Properties.

In this study, we introduce the count-based Morgan fingerprint (C-MF) to represent chemical structures of contaminants and develop machine learning (ML)-based predictive models for their activities and properties. Compared with the binary Morgan fingerprint (B-MF), C-MF not only qualifies the presence or absence of an atom group but also quantifies its counts in a molecule. We employ six different ML algorithms (ridge regression, SVM, KNN, RF, XGBoost, and CatBoost) to develop models on 10 contaminant-related data sets based on C-MF and B-MF to compare them in terms of the model's predictive performance, interpretation, and applicability domain (AD). Our results show that C-MF outperforms B-MF in nine of 10 data sets in terms of model predictive performance. The advantage of C-MF over B-MF is dependent on the ML algorithm, and the performance enhancements are proportional to the difference in the chemical diversity of data sets calculated by B-MF and C-MF. Model interpretation results show that the C-MF-based model can elucidate the effect of atom group counts on the target and have a wider range of SHAP values. AD analysis shows that C-MF-based models have an AD similar to that of B-MF-based ones. Finally, we developed a "ContaminaNET" platform to deploy these C-MF-based models for free use.

Roles of MnO2 Colloids and Mn(III) during the Oxidation of Organic Contaminants by Permanganate.

Although intermediate manganese species can be generated during the reactions of permanganate (Mn(VII)) with organic pollutants in water, the role of the in situ generated MnO2 colloids in the Mn(VII) oxidation process remained controversial and the contribution of Mn(III) was largely neglected. This study showed that the apparent second-order rate constants (kapp) of Mn(VII) oxidation of methyl phenyl sulfoxide and carbamazepine remained constant with time. However, the degradation of four selected phenolic contaminants by Mn(VII) exhibited an autoaccelerating trend and a linear trend at pH 3.0-6.0 and pH 7.0-9.0, respectively. Multiple lines of evidence revealed that the occurrence of the autoaccelerating trend in the Mn(VII) oxidation process was ascribed to the oxidation of the phenolic organics by MnO2 colloids. The influence of pyrophosphate on the oxidation of different organic contaminants by MnO2 colloids suggests that Mn(III) was also responsible for the autoaccelerating oxidation of organic contaminants by Mn(VII) under specific reaction conditions. The kinetic models revealed that the overall contributions of MnO2 colloids and Mn(III) ranged within 6.6-67.9% during the autoaccelerating oxidation of phenolic contaminants by Mn(VII). These findings advance the understanding of the roles of MnO2 colloids and Mn(III) in the Mn(VII) oxidation process.

Selective Removal of Emerging Organic Contaminants from Water Using Electrogenerated Fe(IV) and Fe(V) under Near-Neutral Conditions.

Fe(IV) and Fe(V) are promising oxidants for the selective removal of emerging organic contaminants (EOCs) from water under near-neutral conditions. The Fe(III)-assisted electrochemical oxidation system with a BDD anode (Fe(III)-EOS-BDD system) has been employed to generate Fe(VI), while the generation and contributions of Fe(IV) and Fe(V) have been largely ignored. Thus, we examined the feasibility and involved mechanisms of the selective degradation of EOCs in the Fe(III)-EOS-BDD system under near-neutral conditions. It was found that Fe(III) application selectively accelerated the electro-oxidation of phenolic and sulfonamide organics and made the oxidation system be resistant to interference from Cl-, HCO3-, and humic acid. Several lines of evidence indicated that EOCs were decomposed via direct electron-transfer process on the BDD anode and by Fe(IV) and Fe(V) but not Fe(VI), besides HO•. Fe(VI) was not generated until the exhaustion of EOCs. Furthermore, the overall contributions of Fe(IV) and Fe(V) to the oxidation of phenolic and sulfonamide organics were over 45%. Our results also revealed that Fe(III) was oxidized primarily by HO• to Fe(IV) and Fe(V) in the Fe(III)-EOS-BDD system. This study advances the understanding of the roles of Fe(IV) and Fe(V) in the Fe(III)-EOS-BDD system and provides an alternative for utilizing Fe(IV) and Fe(V) under near-neutral conditions.

Iron(III)-(1,10-Phenanthroline) Complex Can Enhance Ferrate(VI) and Ferrate(V) Oxidation of Organic Contaminants via Mediating Electron Transfer.

Recent research has primarily focused on the utilization of reductants as activators for Fe(VI) to generate high-valent iron species (Fe(IV)/Fe(V)) for the degradation of emerging organic contaminants (EOCs). However, a significant drawback of this approach arises from the reaction between reductants and ferrates, leading to a decrease in oxidation capacity. This study introduces a novel discovery that highlights the potential of the iron(III)-(1,10-phenanthroline) (Fe(III)-Phen) complex as an activator, effectively enhancing the degradation of EOCs by Fe(VI) and augmenting the overall oxidation capacity of Fe(VI). The degradation of EOCs in the Fe(VI)/Fe(III)-Phen system is facilitated through two mechanisms: a direct electron transfer (DET) process and electron shuttle action. The DET process involves the formation of a Phen-Fe(III)-Fe(VI)* complex, which exhibits a stronger oxidation ability than Fe(VI) alone and can accept electrons directly from EOCs. On the other hand, the electron shuttle process utilizes Fe(III)-Phen as a redox mediator to transfer electrons from EOCs to Fe(VI) through the Fe(IV)/Fe(III) or Fe(IV)/Fe(II)/Fe(III) cycle. Moreover, the Fe(III)-Phen complex can improve the utilization efficiency of Fe(V) by preventing its self-decay. This study's findings may present a viable option for utilizing an effective catalyst to enhance the oxidation of EOCs by Fe(VI) and Fe(V).

Naproxen as a Turn-On Chemiluminescent Probe for Real-Time Quantification of Sulfate Radicals.

Current techniques for identifying and quantifying sulfate radicals (SO4·-) in SO4·--based advanced oxidation processes (SR-AOPs) are unsatisfactory due to their low selectivity, poor reliability, and limited feasibility for real-time quantification. In this study, naproxen (NAP) was employed as a turn-on luminescent probe for real-time quantification of SO4·- in SR-AOPs. The chemiluminescence(CL) yield (ΦCL) of the reaction of NAP with SO4·- was first determined to be 1.49 × 10-5 E mol-1 with the bisulfite activation by cerium(IV) [Ce(IV)/BS] process. Then, the maximum peak concentrations of SO4·- in the Ce(IV)/BS-NAP process was quantified to be ∼10-11 M based on the derived equation. Since ΦCL of the reaction of NAP with SO4·- was much greater than that with other reactive oxidizing species (ROS), the developed CL method worked well in selective quantification of SO4·- in various SR-AOPs (e.g., the activation of peroxymonosulfate and persulfate by iron processes). Finally, the electron transfer from NAP to SO4·- was proposed to be the critical step for CL production. This work provides a novel CL method for real-time quantification of SO4·-, which facilitates the development of SR-AOPs and their application in water and wastewater treatment.

Neutral Phenolic Contaminants Are Not Necessarily More Resistant to Permanganate Oxidation Than Their Dissociated Counterparts: Importance of Proton-Coupled Electron Transfer.

Despite decades of research on phenols oxidation by permanganate, there are still considerable uncertainties regarding the mechanisms accounting for the unexpected parabolic pH-dependent oxidation rate. Herein, the pH effect on phenols oxidation was reinvestigated experimentally and theoretically by highlighting the previously unappreciated proton transfer. The results revealed that the oxidation of protonated phenols occurred via proton-coupled electron transfer (PCET) pathways, which can switch from ETPT (electron transfer followed by proton transfer) to CEPT (concerted electron-proton transfer) or PTET (proton transfer followed by electron transfer) with an increase in pH. A PCET-based model was thus established, and it could fit the kinetic data of phenols oxidation by permanganate well. In contrast with what was previously thought, both the simulating results and the density functional theory calculation indicated the rate of CEPT reaction of protonated phenols with OH- as the proton acceptor was much higher than that of deprotonated phenols, which could account for the pH-rate profiles for phenols oxidation. Analysis of the quantitative structure-activity relationships among the modeled rate constants, Hammett constants, and pKa values of phenols further supports the idea that the oxidation of protonated phenols is dominated by PCET. This study improves our understanding of permanganate oxidation and suggests a new pattern of reactivity that may be applicable to other systems.

Simultaneous Sequestration of Humic Acid-Complexed Pb(II), Zn(II), Cd(II), and As(V) by Sulfidated Zero-Valent Iron: Performance and Stability of Sequestration Products.

Heavy metal(loid)s (HMs) such as Pb(II), Zn(II), Cd(II), and As(V) are ubiquitously present in co-contaminated soil and shallow groundwater, where the humic acid (HA)-rich environments can significantly influence their sequestration. In this study, sulfidated zero-valent iron (S-ZVI) was found to be able to simultaneously sequestrate these HA-complexed HMs. Specially, the HA-complexed Pb(II), Zn(II), Cd(II), and As(V) could be completely removed by S-ZVI within 60 min, while only 35-50% of them could be sequestrated within 72 h by unsulfidated ZVI. Interestingly, different from the S-ZVI corrosion behavior, the kinetics of HM sequestration by S-ZVI consisted of an initial slow reaction stage (or a lag phase) and then a fairly rapid reaction process. Characterization results indicated that forming metal sulfides controlled the HM sequestration at the first stage, whereas the enhanced ZVI corrosion and thus-improved adsorption and/or coprecipitation by iron hydroxides governed the second stage. Both metal-oxygen and metal-sulfur bonds in the solid phase could be confirmed by X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis. Moreover, the transformation of S species from SO42-, SO32-, and S22- to S2- under reducing conditions could allow the sequestrated HMs to remain stable over a long period.

Understanding the Importance of Periodate Species in the pH-Dependent Degradation of Organic Contaminants in the H2O2/Periodate Process.

Although periodate-based advanced oxidation processes have been proven to be efficient in abating organic contaminants, the activation properties of different periodate species remain largely unclear. Herein, by highlighting the role of H4IO6-, we reinvestigated the pH effect on the decontamination performance of the H2O2/periodate process. Results revealed that elevating pH from 2.0 to 10.0 could markedly accelerate the rates of organic contaminant decay but decrease the amounts of organic contaminant removal. This pH-dependent trend of organic contaminant degradation corresponded well with the HO· yield and the variation of periodate species. Specifically, although 1O2 could be detected at pH 9.0, HO· was determined to be the major reactive oxidizing species in the H2O2/periodate process under all the tested pH levels. Furthermore, it was suggested that only H4IO6- and H2I2O104- could serve as the precursors of HO·. The second-order rate constant for the reaction of H2I2O104- species with H2O2 was determined to be ∼1199.5 M-1 s-1 at pH 9.0, which was two orders of magnitude greater than that of H4IO6- (∼2.2 M-1 s-1 at pH 3.0). Taken together, the reaction pathways of H2O2 with different periodate species were proposed. These fundamental findings could improve our understanding of the periodate-based advanced oxidation processes.

Novel Denitrification Fuel Cell for Energy Recovery of Nitrate-N and TN Removal Based on NH4+ Generation on a CNW@CF Cathode.

NO3- is an undesirable environmental pollutant that causes eutrophication in aquatic ecosystems, and its pollution is difficult to eliminate because it is easily converted into NH4+ instead of N2. Additionally, it is a high-energy substance. Herein, we propose a novel denitrification fuel cell to realize the chemical energy recovery of NO3- and simultaneous conversion of total nitrogen (TN) into N2 based on the outstanding ability of NH4+ generation on a three-dimensional copper nanowire (CNW)-modified copper foam (CF) cathode (CNW@CF). The basic steps are as follows: direct and highly selective reduction of NO3- to NH4+ rather than to N2 on the CNW@CF cathode, on which negative NO3- ions can be easily adsorbed due to their double-electron layer structure and active hydrogen ([H]) can be generated due to a large number of catalytic active sites exposed on CNWs. Then, NH4+ is selectively oxidized to N2 by the strong oxidation of chlorine free radicals (Cl•), which originate from the reaction of chlorine ions (Cl-) by photogenerated holes (h+) and hydroxyl radicals (OH•) under irradiation. Then, the electrons from the oxidation on the photoanode is transferred to the cathode to form a closed loop for external power generation. Owing to the continuous redox loop, NO3- completely reduces to N2, and the released chemical energy is converted into electrical energy. The results indicate that 99.9% of NO3- can be removed in 90 min, and the highest yield of electrical power density reaches 0.973 mW cm-2, of which the nitrate reduction rates on the CNW@CF cathode is 79 and 71 times higher than those on the Pt and CF cathodes, respectively. This study presents a novel and robust energy recycling concept for treating nitrate-rich wastewater.

Mechanistic Insights into the Markedly Decreased Oxidation Capacity of the Fe(II)/S2O82- Process with Increasing pH.

The poor oxidation capacity of the Fe(II)/S2O82- [Fe(II)/PDS] system at pH > 3.0 has limited its wide application in water treatment. To unravel the underlying mechanism, this study systematically evaluated the possible influencing factors over the pH range of 1.0-8.0 and developed a mathematical model to quantify these effects. Results showed that ∼82% of the generated Fe(IV) could be used for pollutant degradation at pH 1.0, whereas negligible Fe(IV) contribution was observed at pH 7.5. This dramatic decline of Fe(IV) contribution with increasing pH dominantly accounted for the pH-dependent performance of the Fe(II)/PDS process. Unexpectedly, Fe(II) could consume ∼80% of the generated SO4•- non-productively under both acidic and near-neutral conditions, while the larger formation of Fe(III) precipitates at high pH inhibited the SO4•- contribution mildly. Moreover, the strong Fe(II) scavenging effect was difficult to be compensated for by slowing down the Fe(II) dosing rate. The competition of dissolved oxygen with PDS for Fe(II) was insignificant at pH ≤ 7.5, where the second-order rate constants for reactions of Fe(II) with oxygen were much lower than or comparable to that between Fe(II) and PDS. These findings could advance our understanding of the chemistry and application of the Fe(II)/PDS process.

Sevoflurane activates MEF2D-mediated Wnt/ß-catenin signaling pathway via microRNA-374b-5p to affect renal ischemia/reperfusion injury.

BACKGROUND: The inhaled sevoflurane (Sev) has been demonstrated to protect multiple organs against ischemia/reperfusion injury (IRI). However, the mechanisms of Sev in renal IRI remain largely unknown. This study intends to explore the effect of Sev on renal IRI and the molecular mechanism behind. METHODS: Following Sev preconditioning, a mouse model with renal IRI was established. The effects of Sev on IRI in mice were assessed by BUN, Scr, MDA and SOD kits, Western blot, HE staining, and TUNEL. Subsequently, we performed microarray analysis on renal tissues from mice with Sev to identify differentially expressed microRNAs (miRNAs). Then, the mice were treated with agomiR-374b-5p combined with Sev to observe the renal histopathology after IRI. The targeting mRNA of miR-374b-5p was verified using bioinformatics analysis and dual-luciferase assay, followed by KEGG enrichment analysis. Rescue experiments were implemented with simultaneous miR-374b-5p and MEF2D overexpression to detect renal histopathology and Wnt/ß-catenin pathway activity in the mice. RESULTS: Sev significantly reduced the levels of BUN and Scr in mouse serum, prevented cell apoptosis, decreased MDA content and increased SOD levels in renal tissues. Moreover, Sev downregulated the miR-374b-5p expression in the renal tissues. Overexpression of miR-374b-5p attenuated the protective effects of Sev on mouse renal tissues. miR-374b-5p targeted MEF2D and blocked the Wnt/ß-catenin pathway. Overexpression of MEF2D activated the Wnt/ß-catenin pathway and attenuated the supporting effects of miR-374b-5p on renal IRI. CONCLUSION: Sev promotes MEF2D and activates the Wnt/ß-catenin pathway through inhibition of miR-374b-5p expression to affect renal IRI.

Dexmedetomidine Alleviates Hypoxic-Ischemic Brain Damage in Neonatal Rats Through Reducing MicroRNA-134-5p-Mediated NLRX1 Downregulation.

BACKGROUND: Dexmedetomidine (Dex) is a safe and effective anesthetic adjunct which also has neuroprotective roles. This study aimed to validate the role of Dex in hypoxic-ischemic brain damage (HIBD) in neonatal rats and the functional molecules. METHODS: A neonatal rat model of HIBD was established and treated with Dex. The learning and memory abilities of rats were determined by Morris water maze tests. The left-hemisphere encephalatrophy, pathological changes, neuronal apoptosis, and inflammation in rat hippocampal tissues were examined to evaluate the treating effects of Dex on HIBD. Differentially expressed microRNAs (miRNAs) in rats with HIBD were screened using microarray analysis. Potential downstream molecules mediated by miR-134-5p were predicted using bioinformatics analysis. Altered expression of miR-134-5p and NLR family member X1 (NLRX1) was induced in rats after Dex treatment for rescue experiments. RESULTS: Dex treatment significantly enhanced the learning and memory abilities of rats and reduced encephalatrophy in rats. It also alleviated pathological changes, neuronal apoptosis, and the production of pro-inflammatory cytokines in rat hippocampal tissues. miR-134-5p was significantly upregulated in rats with HIBD. Dex treatment reduced the expression of miR-134-5p. NLRX1 was a target gene of miR-134-5p and it reduced the phosphorylation of IκBα and p65, namely the activation of NF-κB signaling. Overexpression of miR-134-5p blocked, whereas overexpression of NLRX1 strengthened the protective effects of Dex on neonatal rats. CONCLUSION: This study demonstrates that Dex treatment can alleviate HIBD in neonatal rats through restoring NLRX1 expression by suppressing miR-134-5p.

Architectural Genesis of Metal(loid)s with Iron Nanoparticle in Water.

Reactions of core-shell iron nanoparticles with metal(loid)s in water can form an array of nanostructures such as Ag-seed/dendrite, As-subshell, U-yolk, Co-hollowshell, and Cs-spot. Nonetheless, there is a lack of profound understanding in the genesis of these amazing geometries. Herein, we propose a concept to unravel the interdiffusion between the core-shell iron nanoparticle and metal(loid)s, where several key interactions including the Kirkendall effect, metal(loid) character effect, and reaction condition effect are involved in determining the structure of the final solid reaction products. Particularly, the architectural growths of metal(loid)s with iron nanoparticles in water can be manipulated mutually or singly by the following factors: standard redox potential difference, magnetic property, electrical charge and conductivity, as well as the iron (hydr)oxide shell structure under different solution chemistry and operation conditions. This contribution provides a theoretical basis to rationalize the architectural genesis of various metal(loid)s with iron nanoparticles, which will benefit the real practice for synthesizing functional iron-based nanoparticles and recovering the rare/precious metal(loid)s by iron nanoparticles from water.

Three Kinetic Patterns for the Oxidation of Emerging Organic Contaminants by Fe(VI): The Critical Roles of Fe(V) and Fe(IV).

For the first time, this study showed that the apparent second-order rate constants (kapp) of six selected emerging organic contaminants (EOCs) oxidation by Fe(VI) increased, remained constant, or declined with time, depending on [EOC]0/[Fe(VI)]0, pH, and EOCs species. Employing excess caffeine as the quenching reagent for Fe(V) and Fe(IV), it was found that Fe(V)/Fe(IV) contributed to 20-30% of phenol and bisphenol F degradation by Fe(VI), and the contributions of Fe(V)/Fe(IV) remained nearly constant with time under all the tested conditions. However, the contributions of Fe(V)/Fe(IV) accounted for over 50% during the oxidation of sulfamethoxazole, bisphenol S, and iohexol by Fe(VI), and the variation trends of kapp of their degradation by Fe(VI) with time displayed three different patterns, which coincided with those of the contributions of Fe(V)/Fe(IV) to their decomposition with time. Results of the quenching experiments were validated by simulating the oxidation kinetic data of methyl phenyl sulfoxide by Fe(VI), which revealed that the variation trends of kapp with time were significantly determined by the change in the molar ratio of Fe(V) to Fe(VI) with time, highlighting the key role of Fe(V) in the oxidative process. This study provides comprehensive and insightful information on the roles of Fe(V)/Fe(IV) during EOC oxidation by Fe(VI).

Degradation of Organic Contaminants in the Fe(II)/Peroxymonosulfate Process under Acidic Conditions: The Overlooked Rapid Oxidation Stage.

The iron(II)-activated peroxymonosulfate [Fe(II)/PMS] process is effective in degrading organic contaminants with a rapid oxidation stage followed by a slow one. Nevertheless, prior studies have greatly underestimated the degradation rates of organic contaminants in the rapid oxidation stage and ignored the differences in the kinetics and mechanism of organic contaminants degradation in these two oxidation stages. In this work, we investigated the kinetics and mechanisms of organic contaminants in this process under acidic conditions by combining the stopped-flow spectrophotometric method and batch experiments. The organic contaminants were rapidly oxidized with rate constants of 0.18-2.9 s-1 in the rapid oxidation stage. Meanwhile, both Fe(IV) and SO4•- were active oxidants and contributed differently to the degradation of different organic contaminants in this stage. Additionally, the presence of Cl- promoted the degradation of both phenol and estradiol but the effects of Br- and humic acid on phenol degradation differed from those on estradiol degradation in the rapid oxidation stage. In contrast, the degradation of phenol and estradiol was slow and the amounts of Fe(IV) and SO4•- generated were small in the slow oxidation stage. This work updates the fundamental understanding of the degradation of organic contaminants in this process.

Single-Atom Fe Catalyst Outperforms Its Homogeneous Counterpart for Activating Peroxymonosulfate to Achieve Effective Degradation of Organic Contaminants.

Recently, reactive iron species (RFeS) have shown great potential for the selective degradation of emerging organic contaminants (EOCs). However, the rapid generation of RFeS for the selective and efficient degradation of EOCs over a wide pH range is still challenging. Herein, we constructed FeN4 structures on a carbon nanotube (CNT) to obtain single-atom catalysts (FeSA-N-CNT) to generate RFeS in the presence of peroxymonosulfate (PMS). The obtained FeSA-N-CNT/PMS system exhibited outstanding and selective reactivity for oxidizing EOCs over a wide pH range (3.0-9.0). Several lines of evidences suggested that RFeS existing as an FeN4═O intermediate was the predominant oxidant, while SO4·- and HO· were the secondary oxidants. Density functional theory calculation results revealed that a CNT played a key role in optimizing the distribution of bonding and antibonding states in the Fe 3d orbital, resulting in the outstanding ability of FeSA-N-CNT for PMS chemical adsorption and activation. Moreover, CNT could significantly enhance the reactivity of the FeN4═O intermediate by increasing the overlap of electrons of the Fe 3d orbital, O 2p orbital, and bisphenol A near the Fermi level. The results of this study can advance the understanding of RFeS generation in a heterogeneous system over a wide pH range and the application of RFeS in real practice.

Very-low-dose decitabine treatment for patients with intermediate- or high-risk myelodysplastic syndrome: a retrospective analysis of thirteen cases.

Decitabine is a hypomethylating drug that is used to treat myelodysplastic syndrome (MDS) at a recommended dose and schedule (20 mg/m2 per day, for 5 consecutive days). However, due to its relatively high incidence of side effects and its effects on neoplastic cells, many studies have begun to explore the clinical application of a low dose of decitabine for treating MDS. In this retrospective study, we examined the effects of a very-low-dose decitabine schedule for treating MDS. A total of 13 patients diagnosed with de novo MDS received a schedule of intravenous decitabine administration at 6 mg/m2 per day for 7 days, repeated every 4 weeks. The complete response rate was 30.8%, and the overall response rate was 69.2%. In patients with complete remission, the median time to granulocyte recovery greater than 0.5 × 109/L during complete remission (CR) was 15 days. In patients with remission, the median time to granulocyte recovery greater than 0.5 × 109/L was 10.5 days. The 1-year survival rate was 72.7% and the median survival was 28.0 months. In summary, we demonstrated that a very-low-dose decitabine schedule has an appreciable response and survival rate, as well as appreciable tolerance and medical compliance for treating MDS.

Unraveling the Overlooked Involvement of High-Valent Cobalt-Oxo Species Generated from the Cobalt(II)-Activated Peroxymonosulfate Process.

Sulfate radical (SO4•-) is widely recognized as the predominant species generated from the cobalt(II)-activated peroxymonosulfate (PMS) process. However, in this study, it was surprisingly found that methyl phenyl sulfoxide (PMSO) was readily oxidized to the corresponding sulfone (PMSO2) with a transformation ratio of ∼100% under acidic conditions, which strongly implied the generation of high-valent cobalt-oxo species [Co(IV)] instead of SO4•- in the Co(II)/PMS process. Scavenging experiments using methanol (MeOH), tert-butyl alcohol, and dimethyl sulfoxide further suggested the negligible role of SO4•- and hydroxyl radical (•OH) but favored the generation of Co(IV). By employing 18O isotope-labeling technique, the formation of Co(IV) was conclusively verified and the oxygen atom exchange reaction between Co(IV) and H2O was revealed. Density functional theory calculation determined that the formation of Co(IV) was thermodynamically favorable than that of SO4•- and •OH in the Co(II)/PMS process. The generated Co(IV) species was indicated to be highly reactive due to the existence of oxo-wall and capable of oxidizing the organic pollutant that is rather recalcitrant to SO4•- attack, for example, nitrobenzene. Additionally, the degradation intermediates of sulfamethoxazole (SMX) in the Co(II)/PMS process under acidic conditions were identified to further understand the interaction between Co(IV) and the representative contaminant. The developed kinetic model successfully simulated PMSO loss, PMSO2 production, SMX degradation, and/or PMS decomposition under varying conditions, which further supported the proposed mechanism. This study might shed new light on the Co(II)/PMS process.