RESUMEN
BACKGROUND: Macrotrabecular-massive hepatocellular carcinoma (MTM-HCC) is highly aggressive. Comparing the diagnosis ability of CT and gadoxetate disodium (Gd-EOB-DTPA) MRI for MTM-HCC are lacking. PURPOSE: To compare the performance of Gd-EOB-DTPA MRI and CT for differentiating MTM-HCC from non-MTM-HCC, and determine the prognostic indicator. STUDY TYPE: Retrospective. SUBJECTS: Post-surgery HCC patients, divided into the training (N = 272) and external validation (N = 44) cohorts. FIELD STRENGTH/SEQUENCE: 3.0 T, T1-weighted imaging, in-opp phase, and T1-weighted volumetric interpolated breath-hold examination/liver acquisition with volume acceleration; enhanced CT. ASSESSMENT: Three radiologists evaluated clinical characteristics (sex, age, liver disease, liver function, blood routine, alpha-fetoprotein [AFP] and prothrombin time international normalization ratio [PT-INR]) and imaging features (tumor length, intratumor fat, hemorrhage, arterial phase peritumoral enhancement, intratumor necrosis or ischemia, capsule, and peritumoral hepatobiliary phase [HBP] hypointensity). Compared the performance of CT and MRI for diagnosing MTM-HCC. Follow-up occurred every 3-6 months, and nomogram demonstrated the probability of MTM-HCC. STATISTICAL TESTS: Fisher test, t-test or Wilcoxon rank-sum test, area under the curve (AUC), 95% confidence interval (CI), multivariable logistic regression, Kaplan-Meier curve, and Cox proportional hazards. Significance level: P < 0.05. RESULTS: Gd-EOB-DTPA MRI (AUC: 0.793; 95% CI, 0.740-0.839) outperformed CT (AUC: 0.747; 95% CI, 0.691-0.797) in the training cohort. The nomogram, incorporating AFP, PT-INR, and MRI features (non-intratumor fat, incomplete capsule, intratumor necrosis or ischemia, and peritumoral HBP hypointensity) demonstrated powerful performance for diagnosing MTM-HCC with an AUC of 0.826 (95% CI, 0.631-1.000) in the external validation cohort. Median follow-up was 347 days (interquartile range [IQR], 606 days) for the training cohort and 222 days (IQR, 441 days) for external validation cohort. Intratumor necrosis or ischemia was an independent indicator for poor prognosis. DATA CONCLUSION: Gd-EOB-DTPA MRI might assist in preoperative diagnosis of MTM-HCC, and intratumor necrosis or ischemia was associated with poor prognosis. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 2.
RESUMEN
Intermetallic compounds (IMCs) with fixed chemical composition and ordered crystallographic arrangement are highly desirable platforms for elucidating the precise correlation between structures and performances in catalysis. However, diffusing a metal atom into a lattice of another metal to form a controllably regular metal occupancy remains a huge challenge. Herein, we develop a general and tractable solvothermal method to synthesize the Bi-Pd IMCs family, including Bi2Pd, BiPd, Bi3Pd5, Bi2Pd5, Bi3Pd8 and BiPd3. By employing electrocatalytic CO2 reduction as a model reaction, we deeply elucidated the interplay between Bi-Pd IMCs and key intermediates. Specific surface atomic arrangements endow Bi-Pd IMCs different relative surface binding affinities and adsorption configuration for *OCHO, *COOH and *H intermediate, thus exhibiting substantially selective generation of formate (Bi2Pd), CO (BiPd3) and H2 (Bi2Pd5). This work provides a comprehensive understanding of the specific structure-performance correlation of IMCs, which serves as a valuable paradigm for precisely modulating catalyst material structures.
RESUMEN
The emergence of nanomedicine offers renewed promise in the diagnosis and treatment of diseases. Due to their unique physical and chemical properties, iron oxide nanoparticles (IONPs) exhibit widespread application in the diagnosis and treatment of various ailments, particularly tumors. IONPs have magnetic resonance (MR) T1/T2 imaging capabilities due to their different sizes. In addition, IONPs also have biocatalytic activity (nanozymes) and magnetocaloric effects. They are widely used in chemodynamic therapy (CDT), magnetic hyperthermia treatment (MHT), photodynamic therapy (PDT), and drug delivery. This review outlines the synthesis, modification, and biomedical applications of IONPs, emphasizing their role in enhancing diagnostic imaging (including single-mode and multimodal imaging) and their potential in cancer therapies (including chemotherapy, radiotherapy, CDT, and PDT). Furthermore, we briefly explore the challenges in the clinical application of IONPs, such as surface modification and protein adsorption, and put forward opinions on the clinical transformation of IONPs.
RESUMEN
Background: The rapid and accurate diagnosis of fractures is crucial for timely treatment of trauma patients. Deep learning, one of the most widely used forms of artificial intelligence (AI), is now commonly employed in medical imaging for fracture detection. This study aimed to construct a deep learning model using big data to recognize multiple-fracture X-ray images of extremity bones. Methods: Radiographic imaging data of extremities were retrospectively collected from five hospitals between January 2017 and September 2020. The total number of people finally included was 25,635 and the total number of images included was 26,098. After labeling the lesions, the randomized method used 90% of the data as the training set to develop the fracture detection model, and the remaining 10% was used as the validation set to verify the model. The faster region convolutional neural networks (R-CNN) algorithm was adopted to construct diagnostic models for detection. The Dice coefficient was used to evaluate the image segmentation accuracy. The performances of detection models were evaluated with sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). Results: The free-response receiver operating characteristic (FROC) curve value was 0.886 and 0.843 for the detection of single and multiple fractures, respectively. Additionally, the effective identification AUC for all parts was higher than 0.920. Notably, the AUC for wrist fractures reached 0.952. The average accuracy in detecting bone fracture regions in the extremities was 0.865. When analyzing single and multiple lesions at the patient level, the sensitivity was 0.957 for patients with multiple lesions and 0.852 for those with single lesions. In the segmentation task, the training set (the data set used by the machine learning model to train and learn) and the validation set (the data set used to evaluate the performance of the model) reached 0.996 and 0.975, respectively. Conclusions: The faster R-CNN training algorithm exhibits excellent performance in simultaneously identifying fractures in the hands, feet, wrists, ankles, radius and ulna, and tibia and fibula on X-ray images. It demonstrates high accuracy, low false-negative rates, and controllable false-positive rates. It can serve as a valuable screening tool.
RESUMEN
This study aimed to explore the efficacy and potential mechanisms of rechallenge therapy with microtubule-targeting agents (MTAs) in patients with HER2-low metastatic breast cancer (MBC). We performed a systematic review to investigate the rechallenge treatment concept in the field of HER2-low MBC treatment and utilized a series of cases identified in the literature to illustrate the concept. Here we reported two clinical cases of HER2-low MBC patients whose disease progressed after prior treatment with MTAs such as docetaxel and vincristine. When rechallenged with disitamab vedotin ((RC48-antibody-drug conjugate (ADC), a monomethyl auristatin (MMAE) MTA)), both patients achieved a partial response and the final progression-free survival (PFS) was 13.5 and 9 months, respectively. Genomic profiling detected a PIK3CA H1047R mutation in the patients. The patients were treated with everolimus before being rechallenged with RC48, which may lead to a better response. This study further summarizes and analyzes the potential mechanism of the PI3K-AKT signaling pathway in MTA resistance and reveals that the PIK3CA H1047R mutation may be a potential molecular marker for the efficacy prediction of mTOR inhibitors, providing new insights and potential therapeutic strategies for the application of MTAs to MBC patients.
RESUMEN
Bone marrow metastasis (BMM) of solid tumors refers to a group of diseases that originate from non-hematopoietic malignant tumor cells invading the bone marrow (BM) through complex metastatic patterns. If BMM identification is delayed, the disease will rapidly develop into disseminated carcinogenesis of the BM, which manifests as a series of hematological disorders and microangiopathic hemolytic anemia, leading to serious life-threatening conditions. Although the study of solid tumor BMM is receiving increasing attention, study remains limited, and most descriptions are derived from case reports. Currently, clinicians have insufficient understanding of BMM, and BMM occurrence is often not recognized early or treated effectively, resulting in high mortality rates. In this article, we review the epidemiology, molecular mechanisms, clinical diagnosis, treatment, and prognosis of solid tumor BMM.
Asunto(s)
Neoplasias de la Médula Ósea , Neoplasias Óseas , Humanos , Médula Ósea/patología , Pronóstico , Neoplasias de la Médula Ósea/diagnóstico , Neoplasias de la Médula Ósea/terapia , Neoplasias Óseas/patologíaRESUMEN
Background: Radiographic severity assessment can be instrumental in diagnosing postoperative pulmonary complications (PPCs) and guiding oxygen therapy. The radiographic assessment of lung edema (RALE) and Brixia scores correlate with disease severity, but research on low-risk elderly patients is lacking. This study aimed to assess the efficacy of two chest X-ray scores in predicting continuous oxygen therapy (COT) treatment failure in patients over 70 years of age after thoracic surgery. Methods: From January 2019 to December 2021, we searched for patients aged 70 years and above who underwent thoracic surgery and received COT treatment, with a focus on those at low risk of respiratory complications. Bedside chest X-rays, RALE, Brixia scores, and patient data were collected. Univariate, multivariate analyses, and 1:2 matching identified risk factors. Receiver operating characteristic (ROC) curves determined score sensitivity, specificity, and predictive values. Results: Among the 242 patients surviving to discharge, 19 (7.9%) patients experienced COT failure. COT failure correlated with esophageal cancer surgeries, thoracotomies (36.8% vs. 9%, P=0.003; 26.3% vs. 9.4%, P=0.004), and longer operation time (3.4 vs. 2.8 h, P=0.003). Surgical approach and RALE score were independent risk factors. The prediction model had an area under the curve (AUC) of 0.839 [95% confidence interval (CI), 0.740-0.938]. Brixia and RALE scores predicted COT failure with AUCs of 0.764 (95% CI, 0.650-0.878) with a cut-off value of 6.027 and 0.710 (95% CI, 0.588-0.832) with a cut-off value of 17.134, respectively, after 1:2 matching. Conclusions: The RALE score predict the risk of COT failure in elderly, low-risk thoracic patients better than the Brixia score. This simple, cheap, and noninvasive method helps evaluate postoperative lung damage, monitor treatment response, and provide early warning for oxygen therapy escalation. Further studies are required to confirm the validity and applicability of this model in different settings and populations.
RESUMEN
Leptomeningeal metastasis (LM) refers to the dissemination of malignant cells in the subarachnoid space, pia, and arachnoid mater and is a severe condition associated with metastatic solid tumors. The most common solid tumor that develops into LM is lung cancer and the incidence increased in patients with advanced non-small-cell lung cancer (NSCLC) with targetable mutations. However, tissue biopsy of LM is inaccessible, leading to the paucity of genomic profiles of LM to guide targeted treatments and explore biological mechanisms. In recent years, liquid biopsy is considered a minimally invasive and dynamic method to trace the genomic alterations of cancer cells and some studies started to perform sequencing of cerebrospinal fluid (CSF) in patients with LM to reveal the targeted mutations and genomic profiles. In this review, we focused on studies performed sequencing of CSF in NSCLC patients with LM and summarized the sequencing results and their commonality. As the only way to reveal the genomic landscapes of LM, our review provided evidence that sequencing of CSF is a promising management method in LM patients to dynamically guide target therapy and monitor intracranial tumor response. Furthermore, it reveals a unique genomic profile of LM including driver genes, drug-resistant mutations, and a number of copy number variations. Sequencing of CSF in LM patients seems to provide more comprehensive genomic information than we expected and the biological significance behind the genomic alternations needs further study.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas , Neoplasias Pulmonares , Carcinomatosis Meníngea , Humanos , Carcinoma de Pulmón de Células no Pequeñas/patología , Neoplasias Pulmonares/patología , Variaciones en el Número de Copia de ADN , Carcinomatosis Meníngea/patología , MutaciónRESUMEN
OBJECTIVE: Increasing evidence suggests that inflammation appears to play a role in the genesis of depression. Berberine has potent anti-inflammatory effects and potential antidepressant activity, although the mechanism by which it works is yet unclear. Our study aimed to investigate the molecular mechanisms through which berberine treats depression and reduces inflammation. METHODS: The CUMS model and behavioral evaluation were utilized in this study to evaluate the efficacy of berberine in the treatment of depression. Berberine's effect on the inflammatory response in CUMS mice was evaluated via ELISA assays and western blotting. Nissl staining was used to observe hippocampal neuronal functional damage. Western blotting, ELISA, ubiquitination tests, and immunoprecipitation were utilized in conjunction with in vitro experiments to study the involvement of Trim65 in the antidepressant effects of berberine. RESULTS: The results suggest that berberine effectively alleviates depressive symptoms, suppresses the expression of genes associated with the NLRP3 inflammasome (NLRP3, cleaved caspase-1, ASC, GSDMD-N, Pro-IL-1ß, IL-1ß, Pro-IL-18, and IL-18), and reduces hippocampal neuronal functional damage in CUMS mice. Further studies showed that knockdown of Trim65 reversed the effects of berberine and increased NLRP3 inflammasome activity. Finally, K285, an important site for Trim65 binding to NLRP3, was identified. CONCLUSION: Our study describes the mechanism of berberine limiting NLRP3 inflammasome activity by promoting the conjugation of Trim65 to NLRP3 and NLRP3 ubiquitination, and suggests NLRP3 inflammasome activation as a prospective target for treating inflammation-associated disorders such as depression.
Asunto(s)
Berberina , Animales , Ratones , Berberina/farmacología , Berberina/uso terapéutico , Depresión/tratamiento farmacológico , Inflamasomas , Interleucina-18 , Proteína con Dominio Pirina 3 de la Familia NLR , Transducción de Señal , Hipocampo , Inflamación/tratamiento farmacológicoRESUMEN
Objectives: For accurate diagnosis of leptomeningeal metastasis (LM) and to avoid unnecessary examinations or lumber puncture (LP), we develop two diagnostic prediction models for patients with solid tumors. Study Design Setting and Participants: This is a retrospective cohort study launched at the Second Affiliated Hospital of Dalian Medical University. In total, 206 patients who had been admitted between January 2005 and December 2021 with a solid tumor and clinical suspicion of LM were enrolled to develop model A. In total, 152 patients of them who underwent LPs for cytology and biochemistry were enrolled to develop model B. Model Development: Diagnostic factors included skull metastasis, active brain metastasis, progressed extracranial disease, number of extracranial organs involved, number of symptoms, cerebrospinal fluid (CSF) protein, and CSF glucose. The outcome predictor was defined as the clinical diagnosis of LM. Logistic least absolute shrinkage and selection operator (LASSO) regression was used to identify relevant variables and fit the prediction model. A calibration curve and the concordance index (c-index) were used to evaluate calibration and discrimination ability. The n-fold cross-validation method was used to internally validate the models. The decision curve analysis (DCA) and the interventions avoided analysis (IAA) were used to evaluate the clinical application. Results: The area under the curve (AUC) values of models A and B were 0.812 (95% CI: 0.751-0.874) and 0.901 (95% CI: 0.852-0.949). Respectively, compared to the first magnetic resonance imaging (MRI) and first LP, models A and B showed a higher AUC (model A vs. first MRI: 0.812 vs. 0.743, p = 0.087; model B vs. first LP: 0.901 vs. 0.800, p = 0.010). The validated c-indexes were 0.810 (95% CI: 0.670-0.952) and 0.899 (95% CI: 0.823-0.977). The calibration curves show a good calibrated ability. The evaluation of clinical application revealed a net clinical benefit and a reduction of unnecessary interventions using the models. Conclusions: The models can help improve diagnostic accuracy when used alone or in combination with conventional work-up. They also exhibit a net clinical benefit in medical decisions and in avoiding unnecessary interventions for patients with LM. Studies focused on external validation of our models are necessary in the future.
RESUMEN
In this work, gold/bismuth oxychloride (Au/BiOCl) nanocomposites with different morphologies were successfully prepared by simple solvothermal method and sodium borohydride reduction method, which exhibited significantly efficient visible-light-driven photocatalytic disinfection for Staphylococcus aureus (S.aureus). Particularly, the flower-like Au/BiOCl nanocomposite showed the highest photocatalytic bactericidal performance among the prepared Au/BiOCl samples. The radical trapping experiments revealed that the hole was the main reactive species responsible for the inactivation of S.aureus over Au/BiOCl composite. The enhanced photocatalytic bactericidal effect could be attributed to the enhanced adsorption intensity of visible light that originated from the surface plasmon resonance (SPR) effect of Au, rapid transfer and space transport of hot electrons caused by the hierarchical structure of BiOCl layered compound. Furthermore, the Au/BiOCl coating prepared on stainless steel wire mesh via in-situ synthesis method exhibited excellent superhydrophilic/underwater superoleophobic performance, which endowed the coating with anti-oil-fouling in water. More importantly, compared with Au/BiOCl powder catalyst, the prepared Au/BiOCl coating with anti-oil-fouling also possessed high photocatalytic bactericidal activity and stable recycling performance.
Asunto(s)
Luz , Acero Inoxidable , Polvos , Oro/farmacología , Oro/química , Antibacterianos/farmacología , Antibacterianos/química , Bacterias , AguaRESUMEN
Purpose: This study aimed to investigate manifestations of the gastric wall and related risk factors in COVID-19 patients with gastrointestinal symptoms by CT. Materials and methods: Two hundred and forty patients diagnosed with COVID-19 by RT-PCR were enrolled from January 2020 to April 2020. Patients showed gastrointestinal symptoms, including nausea, vomiting, or diarrhea. Results of the initial laboratory examination were performed after admission. Chest CT was performed for all patients, with the lower bound including the gastric antrum. The volume of COVID-19 and lungs was segmented, and the ratio was calculated as follows: PV/LV = Volumepneumonia/Volumelungs. Results: Among the 240 patients, 109 presented with gastric wall edema (edema group), and 131 showed no gastric wall edema (non-edema group); the PV/LV values between the two groups were significantly different (P = 0.002). Univariate analysis revealed the following: fibrinogen (Fib), thrombin time (TT), activated partial thromboplastin time (APTT), and albumin (ALB) significantly differed between the two groups (P < 0.05). Binary logistic regression analysis showed that only APTT had a negative effect on gastric wall edema (P = 0.003). Conclusions: SARS-CoV-2 invades the gastrointestinal tract, gastric wall edema is the primary CT manifestation, and gastric wall edema is more likely to occur with a shorter APTT and severe pneumonia, with a slightly longer hospitalization time. Patients with gastric wall edema observed by CT should intervene early, which may improve digestive function, and further strengthen immune potency against COVID-19.
RESUMEN
Background: Breast cancer (BC) is the most common cancer among women worldwide, with enormous heterogeneity. Pyroptosis has a significant impact on the development and progression of tumors. Nonetheless, the possible correlation between pyroptosis-related genes (PRGs) and the BC immune microenvironment has yet to be investigated. Materials and methods: In The Cancer Genome Atlas Breast Cancer cohort, 38 PRGs were shown to be significantly different between malignant and non-malignant breast tissues. The 38 PRGs' consensus clustering grouped 1,089 individuals into two pyroptosis-related (PR) patterns. Using univariate and LASSO-Cox analyses, a PR five-gene predictive signature was constructed based on the differentially expressed genes between two clusters. The tools estimation of stromal and immune cells in malignant tumours using expression data (ESTIMATE), cell type identification by estimating relative subsets Of RNA transcripts (CIBERSORT), and single-sample gene set enrichment analysis (ssGSEA) were used to investigate the BC tumor microenvironment (TME). Results: In TME, the two PR clusters displayed distinct clinicopathological characteristics, survival outcomes, and immunocyte infiltration features. The developed five-signature model (SEMA3B, IGKC, KLRB1, BIRC3, and PSME2) classified BC patients into two risk groups based on the estimated median risk score. Patients in the low-scoring category had a higher chance of survival and more extensive immunocyte infiltration. An external validation set can yield similar results. Conclusion: Our data suggest that PRGs have a significant impact on the BC immunological microenvironment. The PR clusters and associated predictive signature stimulate additional research into pyroptosis in order to optimize therapeutic strategies for BC patients and their responses to immune therapy.
RESUMEN
Rhodamine B (RhB) is used in various industries and its effluent must be effectively treated because of its harmful and carcinogenic nature. In this work, ionothermally synthesized Cu-doped Fe3O4 magnetic nanoparticles (Cu-Fe3O4 MNPs) were found to be a highly efficient heterogeneous Fenton-like catalyst for complete decolorization of the RhB solution with H2O2 at pH ~ 7 and 25 °C. The effects of the catalyst loading, initial concentrations of RhB and H2O2, co-existing natural organic matter and inorganic salts, reaction temperature, and radical scavengers on the catalytic performance of Cu-Fe3O4 were investigated. Monte-Carlo simulations revealed that copper dopants facilitated the activation of H2O2 via adopting a terminal end-on adsorption mode and increased collision frequency by bringing the RhB molecules closer to H2O2 and the magnetite surface. These theoretical calculations provide new insight into the promotional effect of copper dopants in magnetite at molecular level.
Asunto(s)
Cobre , Peróxido de Hidrógeno , Catálisis , Fenómenos Magnéticos , RodaminasRESUMEN
N-doped carbon quantum dots (NCQDs) decorated Bi2O2CO3 heterojunction nanosheets have been successfully constructed by a facile hydrothermal method. The obtained NCQDs/Bi2O2CO3 heterojunction exhibits a wide-spectrum absorption ability and remarkably enhanced photocatalytic activities for ciprofloxacin photodegradation from ultraviolet to near-infrared region. The critical roles of NCQDs and two different charge separation and transfer processes of NCQDs/Bi2O2CO3 heterojunction under different light irradiations have been elucidated. Upon UV light irradiation, NCQDs act as electron reservoirs and a Z-scheme charge transfer process between Bi2O2CO3 and NCQDs promotes electrons transfer and â¢O2- reactive species generation. Under visible and NIR light irradiation, NCQDs act as photosensitizer (hole reservoirs) to harvest solar light and a type-II heterojunction leads to an efficient charge carrier separation and thus high catalytic ability. The mechanisms and pathways of ciprofloxacin degradation driven by different lights are discussed accordingly. This work provides a versatile pathway to well design an efficient wide-spectrum response photocatalyst.
Asunto(s)
Ciprofloxacina , Puntos Cuánticos , Carbono , Catálisis , FotólisisRESUMEN
In this work, particle electrification in the Turbula and horizontally oscillating mixers were investigated for adipic acid, microcrystalline cellulose (MCC), and glycine particles. MCC and glycine particles acquired positive electrostatic charges, while adipic acid particles attained negative charges in both mixers. Adipic acid (of sieved size larger than 500 microm), MCC, and glycine particles were monotonically charged to saturated values, and had negligible wall adhesion. On the contrary, the adipic acid particles, both unsieved and sieved but of smaller sieved size fraction, exhibited very different charging kinetics in the horizontally oscillating mixer. These adipic acid particles firstly acquired charges up to a maximum value, and then the charges slowly reduced to a lower saturated value with increasing mixing time. Furthermore, these particles were found to adhere to the inner wall of the mixer, and the adhesion increased with mixing time. Surface specific charge densities for adipic acid particles were estimated based on particle size distribution, and were found to increase with particle mean diameters under the conditions investigated. The results obtained from the current work suggested that electrostatic force enhanced particle-wall adhesion, and the adhered particles can have a significant impact on particle electrification.
Asunto(s)
Química Farmacéutica , Composición de Medicamentos/instrumentación , Adhesividad , Adipatos/química , Algoritmos , Celulosa/química , Electroquímica , Excipientes , Glicina/química , Humedad , Procesamiento de Imagen Asistido por Computador , Tamaño de la Partícula , PolvosRESUMEN
Fe3O4 magnetic nanoparticles (MNPs) are attractive heterogeneous Fenton-like catalysts for oxidative degradation of organic pollutants with H2O2. Herein highly efficient and stable Fe3O4 MNPs (Fe3O4-op-DES, ca. 10nm) were successfully prepared via a novel oxidative precipitation-combined ionothermal synthesis, which comprised oxidative precipitation of FeSO4·7H2O in choline chloride:2urea deep eutectic solvent. Among five different Fe3O4 particles tested, Fe3O4-op-DES MNPs exhibited the highest catalytic activity with the activation energy of 47.6kJmol-1 for degradation of Rhodamine B (RhB) with H2O2 under the same conditions (Fe3O4 dosage of 0.50gL-1, H2O2 concentration of 40mmolL-1, pH 6.4, 55°C, 2h). Fe3O4-op-DES MNPs were magnetically recoverable, and had good catalytic stability and recyclability without the need of regeneration (>98% degradation efficiency of RhB in 2h and pseudo-first-order rate constant of 0.0376min-1 after having been continuously running for 12h). The superior catalytic performance of Fe3O4-op-DES MNPs was attributed to the combination of multiple technologically important features, including the nanometer size, high Fe2+ content, large surface area, high density of surface active sites and stable crystal structure (no phase transformation, negligible iron leaching and particle aggregation after reaction). The wide applicability of Fe3O4-op-DES MNPs was also demonstrated by the degradation of four other organic pollutants.
RESUMEN
A method established in the present study has proven to be effective in the synthesis of Mn(2)O(3) nanocrystals by the thermolysis of manganese(III) acetyl acetonate ([CH(3)COCH=C(O)CH(3)](3)-Mn) and Mn(3)O(4) nanocrystals by the thermolysis of manganese(II) acetyl acetonate ([CH(3)COCH=C(O)-CH(3)](2)Mn) on a mesoporous silica, SBA-15. In particular, Mn(2)O(3) nanocrystals are the first to be reported to be synthesized on SBA-15. The structure, texture, and electronic properties of nanocomposites were studied using various characterization techniques such as N2 physisorption, X-ray diffraction (XRD), laser Raman spectroscopy (LRS), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results of powder XRD at low angles show that the framework of SBA-15 remains unaffected after generation of the manganese oxide (MnO(x)) nanoparticles, whereas the pore volume and the surface area of SBA-15 dramatically decreased as indicated by N2 adsorption-desorption. TEM images reveal that the pores of SBA-15 are progressively blocked with MnO(x) nanoparticles. The formation of the hausmannite Mn(3)O(4) and bixbyite Mn(2)O(3) structures was clearly confirmed by XRD. The surface structures of MnO(x) were also determined by LRS, XPS, and TPR. The crystalline phases of MnO(x) were identified by LRS with corresponding out-of-plane bending and symmetric stretching vibrations of bridging oxygen species (M-O-M) of both MnO(x) nanoparticles and bulk MnO(x). We also observed the terminal Mn=O bonds corresponding to vibrations at 940 and 974 cm-1 for Mn(3)O(4)/SBA-15 and Mn(2)O(3)/SBA-15, respectively. These results show that the MnO(x) species to be highly dispersed inside the channels of SBA-15. The nanostructure of the particles was further identified by the TPR profiles. Furthermore, the chemical states of the surface manganese (Mn) determined by XPS agreed well with the findings of LRS and XRD. These results suggest that the method developed in the present study resulted in the production of MnO(x) nanoparticles on mesoporous silica SBA-15 by controlling the crystalline phases precisely. The thus-prepared nanocomposites of MnO(x) showed significant catalytic activity toward CO oxidation below 523 K. In particular, the MnO(x) prepared from manganese acetyl acetonate showed a higher catalytic reactivity than that prepared from Mn(NO(3))2.
RESUMEN
Compared with Co/MgO catalysts with high Co loading and without Mo addition, the addition of Mo oxide to low Co-loading Co/MgO catalysts can promote the growth of smaller sized Co-encapsulated carbon nanoballs (CNBs) by the decomposition of methane. The catalysts were carefully studied by X-ray photoelectronspectroscopy (XPS), X-ray diffraction (XRD), and temperature-programmed reduction (TPR). The promotion effect of Mo on the increase in the carbon deposition and the reduction in the CNB size, as well as the relation between the carbon product and metal particle size, are discussed.