Alteration of Thyroid Hormones in Mouse Models of Alzheimer's Disease and Aging.

INTRODUCTION: Aging is characterized by the deterioration of a wide range of functions in tissues and organs, and Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment. Hypothyroidism occurs when there is insufficient production of thyroid hormones (THs) by the thyroid. The relationship between hypothyroidism and aging as well as AD is controversial at present. METHODS: We established an animal model of AD (FAD4T) with mutations in the APP and PSEN1 genes, and we performed a thyroid function test and RNA sequencing (RNA-Seq) of the thyroid from FAD4T and naturally aging mice. We also studied gene perturbation correlation in the FAD4T mouse thyroid, bone marrow, and brain by further single-cell RNA sequencing (scRNA-seq) data of the bone marrow and brain. RESULTS: In this study, we found alterations in THs in both AD and aging mice. RNA-seq data showed significant upregulation of T-cell infiltration- and cell proliferation-related genes in FAD4T mouse thyroid. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that upregulated genes were enriched in the functional gene modules of activation of immune cells. Downregulated energy metabolism-related genes were prominent in aging thyroids, which reflected the reduction in THs. GSEA showed a similar enrichment tendency in both mouse thyroids, suggesting their analogous inflammation state. In addition, the regulation of leukocyte activation and migration was a common signature between the thyroid, brain, and bone marrow of FAD4T mice. CONCLUSIONS: Our findings identified immune cell infiltration of the thyroid as the potential underlying mechanism of the alteration of THs in AD and aging.

Structural Insights into M1 Muscarinic Acetylcholine Receptor Signaling Bias between Gαq and ß-Arrestin through BRET Assays and Molecular Docking.

The selectivity of drugs for G protein-coupled receptor (GPCR) signaling pathways is crucial for their therapeutic efficacy. Different agonists can cause receptors to recruit effector proteins at varying levels, thus inducing different signaling responses, called signaling bias. Although several GPCR-biased drugs are currently being developed, only a limited number of biased ligands have been identified regarding their signaling bias for the M1 muscarinic acetylcholine receptor (M1mAChR), and the mechanism is not yet well understood. In this study, we utilized bioluminescence resonance energy transfer (BRET) assays to compare the efficacy of six agonists in inducing Gαq and ß-arrestin2 binding to M1mAChR. Our findings reveal notable variations in agonist efficacy in the recruitment of Gαq and ß-arrestin2. Pilocarpine preferentially promoted the recruitment of ß-arrestin2 (∆∆RAi = -0.5), while McN-A-343 (∆∆RAi = 1.5), Xanomeline (∆∆RAi = 0.6), and Iperoxo (∆∆RAi = 0.3) exhibited a preference for the recruitment of Gαq. We also used commercial methods to verify the agonists and obtained consistent results. Molecular docking revealed that certain residues (e.g., Y404, located in TM7 of M1mAChR) could play crucial roles in Gαq signaling bias by interacting with McN-A-343, Xanomeline, and Iperoxo, whereas other residues (e.g., W378 and Y381, located in TM6) contributed to ß-arrestin recruitment by interacting with Pilocarpine. The preference of activated M1mAChR for different effectors may be due to significant conformational changes induced by biased agonists. By characterizing bias towards Gαq and ß-arrestin2 recruitment, our study provides insights into M1mAChR signaling bias.

Impact of Patient Navigation on Population-Based Breast Screening: a Systematic Review and Meta-analysis of Randomized Clinical Trials.

BACKGROUND: Unsatisfactory cancer screening results are often associated with poor prognosis. This study synthesized the literatures addressing the impact of patient navigation (PN) interventions on population-based breast cancer screening promotion to identify characteristics of the model for addressing breast cancer disparities. METHODS: We searched Pubmed, Embase, Web of Science, and the Cochrane Central Registry from inception to 31 December 2020 for randomized controlled trials (PROSPERO: CRD42021246890). We double blindly abstracted data and assessed study quality. We assessed screening completion rates and diagnostic resolution using random-effects models between those receiving navigation and controls. RESULTS: Of 236 abstracts identified, 15 studies met inclusion criteria. Nine of the papers evaluated the impact of PN on breast screening, while the other six were on the resolution of abnormal screening results. Compared to the non-PN group, PN improved screening completion (OR: 2.0, 95% CI: 1.4-2.8]) and shortened the time to diagnosis (WMD: - 9.90 days, 95% CI: - 19.09 to - 0.71). CONCLUSIONS: Patient navigation improves breast cancer screening rates but does not improve resolution of abnormal tests.

A Comparison of the Seventh and Eighth Editions of the AJCC Staging Systems to Predict Recurrence in Papillary Thyroid Microcarcinoma.

BACKGROUND: The incidence of papillary thyroid microcarcinoma has been constantly rising in recent decades. The tumor, node, metastasis staging system is designed to predict prognosis in patients with papillary thyroid carcinoma. Recent studies have shown that the American Joint Committee on Cancer (AJCC) 8th edition is superior to the 7th edition for predicting tumor recurrence in PTC patients. To date, whether the 8th edition is also better able to predict recurrence in papillary thyroid microcarcinoma (PTMC) remains unclear. METHOD: We enrolled 1007 cases from our thyroid cancer database in the First Affiliated Hospital, Zhejiang University School of Medicine, from 1997 to 2011. Univariable and multivariate Cox hazard regression analyses were used to identify the association between variables and recurrence. Disease-free survival was calculated using the Kaplan-Meier method and compared using the log-rank test. RESULTS: A total of 1007 PTMC patients were enrolled, with a median follow-up of 67 months. Of 93 (9.2%) patients downstaged by the changes in versions, 49 (52.7%) were downstaged because the age-at-diagnosis cut-off used for staging increased from 45 to 55 years, while 35 (37.6%) were downstaged due to the weakening of the effects of lymph node metastasis. The recurrence rate of PTMC was 4.17%. Univariate Cox hazards regression analyses showed that TNM stage according to the AJCC 8th edition was significantly associated with recurrence, while the recurrence survival curves showed that TNM stage (stage I vs. stage II-IV) according to the AJCC 8th edition, but not the 7th edition, was significantly associated with disease-free survival (p < 0.05). CONCLUSIONS: The AJCC 8th edition has better ability to predict recurrence in PTMC patients than the 7th edition.

Coexistence of papillary thyroid carcinoma in secondary hyperparathyroidism.

BACKGROUND: The coexistence of primary hyperparathyroidism and papillary thyroid carcinoma (PTC) is common and may be associative with more aggressive PTC, with higher rates of extrathyroidal extension and multicentricity. However, it is unclear whether secondary hyperparathyroidism (SHPT) is associated with more invasive PTC in terms of morbidity, tumor pathological characteristics, and prognosis. The aim of this study was to evaluate the rate and tumor characteristics of PTC in patients with SHPT. METHODS: A total of 531 patients diagnosed with SHPT who underwent surgery from August 2013 to December 2018 at the First Affiliated Hospital of Zhejiang University were evaluated retrospectively. Patient demographics, surgical records, and follow-up information were recorded and analyzed. Control subjects were matched to the enrolled patients in a 1:4 ratio in terms of age, sex and pathological subtype. RESULTS: Among the 531 patients with SHPT who underwent surgery, 34 had coexisting PTC and PTC + SHPT (6.4%). The mean tumor diameter in the PTC + SHPT group was smaller than that in the PTC group (5.57 mm vs 9.00 mm, p < 0.001). The proportion of papillary thyroid micro-carcinoma in the PTC + SHPT group was significantly higher than that in the PTC group (29 [85.29%] vs. 86[63.24%], p = 0.014). There were no statistically significant differences between groups in terms of tumor multicentricity (15 [44.12%] vs 39 [28.68%], p = 0.066), tumor bilaterality (9 [26.47%] vs. 29 [21.32%], p = 0.499), tumor extrathyroidal extension (2 [5.88%] vs. 19 [13.97%], p = 0.255), or lymph node (LN) metastasis rate (12 [35.29%] vs. 49 [36.03%], p = 1.000). However, the PTC + SHPT and PTC groups were significantly different in terms of contralateral thyroidectomy (10 [29.41%] vs. 70 [51.47%], p = 0.023) and lymph node dissection (22 [64.71%] vs. 125 [91.91%], p < 0.001).There was no significant difference between the PTC + SHPT and PTC groups in terms of prognostic staging (33 [97.06%] vs. 122 [89.71%], p = 0.309) or recurrence (mean follow-up time: 36 months vs. 39 months, p = 0.33). CONCLUSIONS: The prevalence of PTC is high in patients with SHPT; compared with PTC in the general population, most papillary thyroid carcinomas with SHPT are occult thyroid carcinomas and present no significant difference in terms of tumor pathological features and prognostic staging. It is necessary for surgeons to perform more adequate preoperative examination and be more careful during surgery to avoid missing the coexistence of PTC in patients with SHPT.

Nonprecious bimetallic Fe, Mo-embedded N-enriched porous biochar for efficient oxidation of aqueous organic contaminants.

Bimetallic Fe- and Mo-embedded N-enriched porous biochar (Fe-Mo@N-BC) is developed and serves as a cost-effective and highly efficient catalyst for mineralization of non-biodegradation organic contaminants. Fe-Mo@N-BC was prepared by pyrolysis of complex Fe/Mo -containing precursors. Transmission electron microscopy and elemental mapping suggested that Fe and Mo are uniformly dispersed in nitrogen-doped biochar with hierarchical mesopores. In comparison to Fe@N-BC and Mo@N-BC, Fe-Mo@N-BC exhibited a superior activity for activating peroxymonosulfate (PMS). The stable activity was ascribed to N-doping and synergistic effect of Fe and Mo species, where both Fe-Nx and Mo-Nx can simultaneously serve as the active sites and N-BC can act as a carrier and an activator as well as an electron mediator. Electron paramagnetic resonance and quenching experiments indicated that HO•, O2•- and 1O2 were responsible for organic degradation. The effects of PMS dosage, initial Orange II concentration, temperature, solution pH, coexisting anions and humic acids on organic degradation were also investigated. With the assistance of an external magnet, Fe-Mo@N-BC can be easily separated after reaction and remains stable in the reusability tests. This work demonstrates a feasible strategy towards the fabrication of Fe, Mo-embedded N-enriched porous biochar catalysts for the detoxification of organic contaminants.

Pyrite-embedded porous carbon nanocatalysts assembled in polyvinylidene difluoride membrane for organic pollutant oxidation.

FeS2-embedded in porous carbon (FeS2/C) was prepared by simultaneous sulfidation and carbonization of an iron-based metal-organic framework precursor, and subsequently immobilized in polyvinylidene fluoride membranes (FeS2/C@PVDF) for organics removal via peroxymonosulfate (PMS) activation. The composition, structure, and morphology of the FeS2/C@PVDF membrane were extensively characterized. Scanning electron microscopy images manifest that the FeS2/C nanoparticles with an average diameter of 40 nm are assembled on the external and internal membrane surface. The as-prepared FeS2/C@PVDF membrane exhibits excellent performances over a wide pH range of 1.53-9.50, exceeding carbon-free syn-FeS2@PVDF. The effective degradation could be improved by inner pyrite FeS2 cores and thus enhanced the electron transfer between carbon shell and PMS. Electron paramagnetic resonance and quenching experiments elucidated that radical (HO∙, SO4∙-) and nonradical (1O2) species were the predominant reactive oxidants. In addition, FeS2/C@PVDF exhibited high stability with low Fe leaching (0.377 mg/L) owing to the effective protection of the outer carbon skeleton. Plentiful porosity of PVDF membranes not only affords a controlled size and confined uniform distribution of the immobilized FeS2/C nanoparticles, but also enables a persistent exposure of active sites and enhanced mass transfer efficiency. Our findings demonstrate a promise for utilizing the novel FeS2/C@PVDF membrane as an efficient catalyst for the environmental cleanup.

Synthesis and characterization of iron-nitrogen-doped biochar catalysts for organic pollutant removal and hexavalent chromium reduction.

Fe, N atoms deposited on porous biochar (Fe-N@BC) composites were synthesized and employed as an efficient catalyst for organic pollutant removal and CrVI reduction. Naturally abundant, renewable and N-rich pomelo peel as a carbon and nitrogen source and unsubstituted phthalocyanine/iron phthalocyanine complexes as a Fe and nitrogen resource were used to develop the Fe-N@BC via a carbonization process. It is found that Fe-N@BC hybrids have homogeneous dispersion of Fe and N atoms on 3D hierarchically porous biochar, which significantly improves the performance toward the detoxification of organic pollutants using peroxymonosulfate as an oxidant, as well as the reduction of hexavalent chromium by formic acid as a reductant. Furthermore, the effects of Fe loading and pyrolytic temperature on catalysis were comprehensively analyzed and optimized. The excellent activity of Fe-N@BC in acid media can be attributed to the high dispersion of Fe species, high content of doped nitrogen as well as hierarchical micro-mesopores, which induce to expose more active sites for catalysis. Owing to the structure-enabled acidic stability, Fe-N@BC efficiently retains its activity as well as its structural stability after several cycles of reactions. This work provides a new approach to construct Fe, N-doped biochar as an effective catalyst for the detoxification of organic and inorganic pollutants.

Integrative Methylome and Transcriptome Characterization Identifies SERINC2 as a Tumor-Driven Gene for Papillary Thyroid Carcinoma.

Most papillary thyroid carcinomas (PTCs) can be diagnosed preoperatively by routine evaluation, such as thyroid ultrasonography and fine-needle aspiration biopsy. Nevertheless, understanding how to differentiate indolent thyroid tumors from aggressive thyroid cancers remains a challenge, which may cause overtreatment. This study aimed to identify papillary thyroid cancer-specific indicators with whole-genome DNA methylation and gene expression profiles utilizing Infinium Methylation EPIC BeadChip (850k) and RNA arrays. In this paper, we report SERINC2 as a potential tumor-driven indicator in PTC. The up-regulated expression levels of SERINC2 were verified in PTC cell lines via qPCR. Then, cell counting kit 8 (CCK-8), wound healing, and flow cytometric assays were performed to confirm the influence of SERINC2 on proliferation and apoptosis in PTC cell lines after intervention or overexpression. Moreover, the investigation of data from the Cancer Dependency Map (DepMap) provided a potential pathway targeted by SERINC2. The activation of the tryptophan metabolic pathway may reduce the dependency of SERINC2 in thyroid cancers. In conclusion, our results demonstrate the whole-genome DNA methylation and gene expression profiles of papillary thyroid carcinoma, identify SERINC2 as a potential tumor-driven biomarker, and preliminarily verify its function in PTC.

Papillary Thyroid Carcinoma Landscape and Its Immunological Link With Hashimoto Thyroiditis at Single-Cell Resolution.

The tumor microenvironment heterogeneity of papillary thyroid cancer (PTC) is poorly characterized. The relationship between PTC and Hashimoto thyroiditis (HT) is also in doubt. Here, we used single-cell RNA sequencing to map the transcriptome landscape of PTC from eight PTC patients, of which three were concurrent with HT. Predicted copy number variation in epithelial cells and mesenchymal cells revealed the distinct molecular signatures of carcinoma cells. Carcinoma cells demonstrated intertumoral heterogeneity based on BRAF V600E mutation or lymph node metastasis, and some altered genes were identified to be correlated with disease-free survival in The Cancer Genome Atlas datasets. In addition, transcription factor regulons of follicular epithelial cells unveil the different transcription activation state in PTC patients with or without concurrent HT. The immune cells in tumors exhibited distinct transcriptional states, and the presence of tumor-infiltrating B lymphocytes was predominantly linked to concurrent HT origin. Trajectory analysis of B cells and plasma cells suggested their migration potential from HT adjacent tissues to tumor tissues. Furthermore, we revealed diverse ligand-receptor pairs between non-immune cells, infiltrating myeloid cells, and lymphocytes. Our results provided a single-cell landscape of human PTC. These data would deepen the understanding of PTC, as well as the immunological link between PTC and HT.

Integrative Analysis of DNA Methylation and Gene Expression Identified Follicular Thyroid Cancer-Specific Diagnostic Biomarkers.

The diagnosis of follicular thyroid carcinoma (FTC) prior surgical resection remains a challenge, as routine screening methods, such as ultrasound or even FNAB, could not diagnose FTC preoperatively. Here, we performed an integrative analysis of DNA methylation and RNA array data from our own cohort (14 Follicular thyroid carcinoma vs 16 Benign thyroid lesion) to identify thyroid cancer-specific DNA methylation markers. We first identified differentially methylated and expressed genes and examined their correlations. Candidate DNA methylation sites were selected and further verified in validation set. Among all candidate methylation sites, cg06928209 was the most promising site as a molecular marker for early diagnosis, with a sensitivity of 90%, a specificity of 80% and an AUC of 0.77. Overall, our study demonstrates the potential use of methylation markers in FTC diagnosis and may boost the development of new epigenetic therapies.

Identification of Serum Circulating MicroRNAs as Novel Diagnostic Biomarkers of Gastric Cancer.

Gastric cancer (GC) is one of the leading causes of cancer-associated deaths worldwide. Due to the lack of typical symptoms and effective biomarkers for non-invasive screening, most patients develop advanced-stage GC by the time of diagnosis. Circulating microRNA (miRNA)-based panels have been reported as a promising tool for the screening of certain types of cancers. In this study, we performed differential expression analysis of miRNA profiles of plasma samples obtained from gastric cancer and non-cancer patients using two independent Gene Expression Omnibus (GEO) datasets: GSE113486 and GSE124158. We identified three miRNAs, hsa-miR-320a, hsa-miR-1260b, and hsa-miR-6515-5p, to distinguish gastric cancer cases from non-cancer controls. The three miRNAs showed an area under the curve (AUC) over 0.95 with high specificity (>93.0%) and sensitivity (>85.0%) in both the discovery datasets. In addition, we further validated these three miRNAs in two external datasets: GSE106817 [sensitivity: hsa-miR-320a (99.1%), hsa-miR-1260b (97.4%), and hsa-miR-6515-5p (92.2%); specificity: hsa-miR-320a (88.8%), hsa-miR-1260b (89.6%), and hsa-miR-6515-5p (88.7%); and AUC: hsa-miR-320a (96.3%), hsa-miR-1260b (97.4%), and hsa-miR-6515-5p (94.6%)] and GSE112264 [sensitivity: hsa-miR-320a (100.0%), hsa-miR-1260b (98.0%), and hsa-miR-6515.5p (98.0%); specificity: hsa-miR-320a (100.0%), hsa-miR-1260b (100.0%), and hsa-miR-6515.5p (92.7%); and AUC: hsa-miR-320a (1.000), hsa-miR-1260b (1.000), and hsa-miR-6515-5p (0.988)]. On the basis of these findings, the three miRNAs can be used as potential biomarkers for gastric cancer screening, which can provide patients with a higher chance of curative resection and longer survival.

Nonprecious bimetallic (Mo, Fe)-N/C nanostructures loaded on PVDF membrane for toxic CrVI reduction from water.

Nonprecious bimetallic molybdenum and iron embedded into N-doped carbon (MoFe-NC) hybrids were designed and fabricated by pyrolysis of mixed precursors and then immobilized on poly (vinylidene fluoride) (PVDF) films via a phase inversion process to obtain novel catalytic membranes (MoFe-NC@PVDF) for toxic CrVI reduction. The catalytic membranes are highly active for aqueous CrVI reduction using formic acid (FA) as a sacrificial electron donor under mild conditions. The results demonstrated that the parameters of synthesis process can efficiently adjust the morphology and textural properties of the as-synthesized MoFe-NC@PVDF membrane, and thus have a significant impact on the catalytic behavior. CrVI reduction rates significantly increased with increasing FA concentrations (0.234-0.936 M) and reaction temperature (5-35℃), but declined with the increase of CrVI concentrations (5-40 mg/L) and pH values of solution (1.87-4.62). Mo-Nx, Fe-Nx, and C-Nx are the active sites, boosting the dissociation of FA molecules into active H* species for effective catalytic reduction of CrVI. The catalytic PVDF membrane exhibited distinct porous structure and numerous interaction sites, which not only stabilized metallic nanoparticles, but also promoted mass transfer across the membrane. This cost-effective catalytic membrane provides a new approach toward the treatment of CrVI-containing water.

Metal-free catalysts of graphitic carbon nitride-covalent organic frameworks for efficient pollutant destruction in water.

Novel metal-free catalysts via integration of covalent organic framework (COF) and graphitic carbon nitride (g-C3N4@COF) with a high graphitization degree and nitrogen content were fabricated and exhibited an outstanding activity in a wide pH range for peroxymonosulfate (PMS)-driven oxidation of refractory organic pollutants in water. Scanning electron microscopy images showed many aggregated COFs crystals anchored on the irregular g-C3N4 surface to form 3D structures. The precursors (urea, melamine, and dicyandiamide) of g-C3N4 determined the porous structures and properties of the g-C3N4@COF materials. The hybrids possessed superior reactivity in Orange II removal (100%) compared to pristine g-C3N4 (10%) and COF (5%), benefiting from high-temperature pyrolysis to generate crystal carbon and modulate nitrogen doping. Besides, removal efficiency of target pollutants depended on the oxidant dosages (0.33-1.30 mM), initial concentrations of organics (10-40 mg/L), temperatures (5-45 °C), pHs (1.72-10.3), and anions (Cl-, SO42-, NO3-, HCO3-, CO32-, and HCOO-). Quenching experiments and electron paramagnetic resonance demonstrated that non-radical singlet oxygen (1O2) was the dominant species for the oxidation of organic pollutants via electron transfer in the g-C3N4@COF/PMS system. It was inferred that the good balance between graphitization degree and nitrogen content benefited to enhancing the catalytic performance for the refractory pollutant degradation. The present investigation provides a new avenue for the design and construction of metal-free hybrid composites for environmental remediation.

Activation of persulfates by catalytic nickel nanoparticles supported on N-doped carbon nanofibers for degradation of organic pollutants in water.

An N-doped carbon nanofiber cloth (CC) with anchored nickel nanoparticles (Ni@N-CC) was synthesized from a facile pyrolysis process and employed as a catalyst to oxidize target contaminants using peroxydisulfate (PDS) as both radical precursors and electron acceptors. An effective strategy was developed to control the porous structures and catalytic performances by optimizing the precursor weights and pyrolysis temperatures for Ni@N-CC preparation. The optimal temperature was 700 °C, and the best dicyanodiamine mass was 1.0 g. Ni@N-CC was found to be superior for PDS activation to CC and nickel nanoparticles (NPs), ascribing to highly active sites, intimate connection between the nickel NPs and highly conductive N-doped CC, as well as the formed three-dimensional architecture. The oxidation rates were influenced by the oxidant loading (0.185-1.11 mM), initial organics concentration (10-50 mg/L), temperature (5-45 °C), pH (2.65-10.47), and inorganic anions. Furthermore, mechanistic investigations using various probe reagents and spin trapping technique identified the generation of several active species for oxidation. The reaction was found to proceed via the electron transfer mediation from organics to PDS on N-doped CC and one electron reduction of PDS on Ni0 NPs. This study highlights the design of highly active and reusable heterogeneous carbon/metal hybrids for more efficient PDS activation in environmental remediation.

Heteroatoms doped metal iron-polyvinylidene fluoride (PVDF) membrane for enhancing oxidation of organic contaminants.

Iron nanoparticles (NPs) embedded in S, N-codoped carbon were prepared by one-step pyrolysis of a homogeneous mixture consisting of Fe, S, N, C precursors, and then immobilized in poly (vinylidene fluoride) membranes as a multifunctional catalytic system (NSC-Fe@PVDF) to effectively activate peroxymonosulfate (PMS) and oxidize organic compounds in water. The NSC-Fe@PVDF membranes effectively decolorized organic pollutants at a wide pH range (2.05-10.85), due to the synergistic effects between the S, N-doped carbon and iron NPs. The efficiency depended on the doping types, amount of metal, PMS dosages, reaction temperatures, solution pHs, and organic substrates. In-situ electron spin resonance spectroscopy and sacrificial-reagent incorporated catalysis indicate radical intermediates such as sulfate and hydroxyl radicals are mainly responsible for this persulfate-driven oxidation of organic compounds. Membrane's porous structure and high internal surface area not only minimize the NPs agglomeration, but also allow the facile transport of catalytic reactants to the active surface of metal catalysts. The results demonstrate the morphological and structural features of catalytic membranes enhance the overall catalytic activity.

Iron encapsulated in 3D N-doped carbon nanotube/porous carbon hybrid from waste biomass for enhanced oxidative activity.

Novel iron encapsulated in nitrogen-doped carbon nanotubes (CNTs) supported on porous carbon (Fe@N-C) 3D structured materials for degrading organic pollutants were fabricated from a renewable, low-cost biomass, melamine, and iron salt as the precursors. SEM and TEM micrographs show that iron encapsulated bamboo shaped CNTs are vertically standing on carbon sheets, and thus, a 3D hybrid was formed. The catalytic activities of the prepared samples were thoroughly evaluated by activation of peroxymonosulfate for catalytic oxidation of Orange II solutions. The influences of some reaction conditions (pH, temperature, and concentrations of reactants, peroxymonosulfate, and dye) were extensively evaluated. It was revealed that the adsorption could enrich the pollutant which was then rapidly degraded by the catalytically generated radicals, accelerating the continuous adsorption of residual pollutant. Remarkable carbon structure, introduction of CNTs, and N/Fe doping result in promoted adsorption capability and catalytic performances. Due to the simple synthetic process and cheap carbon precursor, Fe@N-C 3D hybrid can be easily scaled up and promote the development of Fenton-like catalysts.

Iron encapsulated in boron and nitrogen codoped carbon nanotubes as synergistic catalysts for Fenton-like reaction.

Iron nanoparticles (NPs) encapsulated in B, N-codoped carbon nanotubes (Fe@C-BN) as heterogeneous Fenton-like catalysts were obtained by a simple and scalable pyrolysis method, and their performances were examined in the oxidative degradation of various organics in the presence of the different oxidants. The results showed that organic dyes can be effectively degraded by Fe@C-BN in the presence of peroxymonosulfate. Calcination temperature and mass of iron salt significantly affected the structures and performances of the catalysts. The effects of several reaction conditions, such as initial dye concentration, oxidant type (peroxymonosulfate, peroxydisulfate, and H2O2) and dosage, initial pH, inorganic anions, reaction temperature and dye types on oxidation as well as the stability of the composite were extensively evaluated in view of the practical applications. Through the investigation of reaction processes, HO(·) and SO4(·-) radicals were identified using quenching experiments. Owing to the synergistic effects between the iron NPs and B, N-doped carbon, Fe@C-BN catalysts intrinsically display an excellent catalytic activity for Fenton-like reaction. This study gives new insights into the design and preparation of iron NPs encapsulated in B, N-codoped carbon nanotubes as an effective strategy to enhance the overall catalytic activity.

Fe, Co, Ni nanocrystals encapsulated in nitrogen-doped carbon nanotubes as Fenton-like catalysts for organic pollutant removal.

Magnetic metal M (M=Fe, Co, Ni) nanocrystals encapsulated in nitrogen-doped carbon nanotubes (M@N-C) were fabricated conveniently using dicyandiamide as a C/N precursor, and exhibited varying activities toward Fenton-like reaction. The surface morphology and structure of the M@N-C catalysts were characterized and an efficient catalytic degradation performance, high stability, and excellent reusability were observed. In addition, several operational factors, such as initial dye concentration, oxidant type (peroxymonosulfate, peroxydisulfate and H2O2) and dosage, reaction temperature, and dye type as well as stability of the composite were extensively evaluated in view of the practical applications. The results showed that various transition metals M significantly affected the structures and performances of the catalysts, and specially, their activity followed the order of Co>Fe>Ni in the presence of peroxymonosulfate. Moreover, HO⁡ and SO4(-) radicals participating in the process were evidenced using quenching experiments, and a rational mechanism was proposed based on a non-radical process and the free radical process. Control experiments revealed that the enhanced active sites were mainly ascribed to the synergistic effects between the metal nanocrystals and nitrogen-doped carbon. The findings of this study elucidated that encapsulation of nanocrystals in nitrogen-doped carbon nanotubes was an effective strategy to enhance the overall catalytic activity.