Planar Chlorination Engineering: A Strategy of Completely Breaking the Geometric Symmetry of Fe-N4 Site for Boosting Oxygen Electroreduction.

Introducing asymmetric elements and breaking the geometric symmetry of traditional metal-N4 site for boosting oxygen reduction reaction (ORR) are meaningful and challenging. Herein, the planar chlorination engineering of Fe-N4 site is first proposed for remarkably improving the ORR activity. The Fe-N4/CNCl catalyst with broken symmetry exhibits a half-wave potential (E1/2) of 0.917 V versus RHE, 49 and 72 mV higher than those of traditional Fe-N4/CN and commercial 20 wt% Pt/C catalysts. The Fe-N4/CNCl catalyst also has excellent stability for 25 000 cycles and good methanol tolerance ability. For Zn-air battery test, the Fe-N4/CNCl catalyst has the maximum power density of 228 mW cm-2 and outstanding stability during 150 h charge-discharge test, as the promising substitute of Pt-based catalysts in energy storage and conversion devices. The density functional theory calculation demonstrates that the adjacent C─Cl bond effectively breaks the symmetry of Fe-N4 site, downward shifts the d-band center of Fe, facilitates the reduction and release of OH*, and remarkably lowers the energy barrier of rate-determining step. This work reveals the enormous potential of planar chlorination engineering for boosting the ORR activity of traditional metal-N4 site by thoroughly breaking their geometric symmetry.

Tracking scheme of airborne star tracker based on event-triggered sliding mode control with known input delay.

The airborne star tracker is crucial in aircraft navigation systems, with its tracking performance directly impacting navigation accuracy. Under airborne conditions, the performance of its tracking control will be compromised by various disturbances. Moreover, the limitation in computational resources is another issue that must be addressed. Assuming that the existing studies on this application did not consider these two aspects of the effects simultaneously, this study proposes a novel event-triggered sliding mode control (ET-SMC) scheme considering the known input time delay for star tracking control to address these two issues. First, an extended state observer (ESO) is presented to estimate the disturbance generated by airborne conditions. Second, the ET-SMC scheme further enhances the robustness and improves resource utilization, thus easing the processor burden. An ET mechanism related to the disturbance estimation triggering error in the ESO is introduced to ensure that the system input is only updated when necessary. A novel, easy-to-implement sliding gain is also proposed to increase system adaptability and reduce inherent chattering. The reachability of the sliding surface and the existence of a practical sliding mode of the system are ensured based on the Lyapunov theory. The ultimate upper bound of system states considering the known input time delay is also proven, thereby confirming the stability of the proposed design. The exclusion of Zeno behavior validates the feasibility of the proposed ESO-based ET-SMC. Finally, the effectiveness of the proposed method is verified using comparative simulations and target-tracking experiments. The experimental results demonstrate that the proposed method excels in robustness, disturbance attenuation, high tracking accuracy, and computational resource efficiency. These enhancements are anticipated to result in a more stable tracking performance for the star tracker, thereby contributing to precise aircraft navigation.

Self-carbon-thermal-reduction strategy for boosting the Fenton-like activity of single Fe-N4 sites by carbon-defect engineering.

Carbon-defect engineering in metal single-atom catalysts by simple and robust strategy, boosting their catalytic activity, and revealing the carbon defect-catalytic activity relationship are meaningful but challenging. Herein, we report a facile self-carbon-thermal-reduction strategy for carbon-defect engineering of single Fe-N4 sites in ZnO-Carbon nano-reactor, as efficient catalyst in Fenton-like reaction for degradation of phenol. The carbon vacancies are easily constructed adjacent to single Fe-N4 sites during synthesis, facilitating the formation of C-O bonding and lowering the energy barrier of rate-determining-step during degradation of phenol. Consequently, the catalyst Fe-NCv-900 with carbon vacancies exhibits a much improved activity than the Fe-NC-900 without abundant carbon vacancies, with 13.5 times improvement in the first-order rate constant of phenol degradation. The Fe-NCv-900 shows high activity (97% removal ratio of phenol in only 5 min), good recyclability and the wide-ranging pH universality (pH range 3-9). This work not only provides a rational strategy for improving the Fenton-like activity of metal single-atom catalysts, but also deepens the fundamental understanding on how periphery carbon environment affects the property and performance of metal-N4 sites.

Atomically Dispersed Pd-N1C3 Sites on a Nitrogen-Doped Carbon Nanosphere for Semi-hydrogenation of Acetylene.

Rationally designing efficient catalysts for semi-hydrogenation of acetylene is significant but challenging. Herein, Pd isolated single-atom sites (ISAS) on a covalent-organic-framework (COF)-derived nanosphere (Pd-ISAS/CN) are synthesized by a COF-absorption-pyrolysis strategy. This synthetic strategy is also applicable for Pt and Ru ISAS catalysts, demonstrating that it is a general method to synthesize noble-metal ISAS on COF-derived carbon materials. Pd-ISAS/CN exhibits outstanding reactivity and high selectivity for semi-hydrogenation of acetylene, with 92% conversion of acetylene, 80% selectivity toward ethylene at 100 °C, and corresponding activity is as high as 712 molacetylene molmetal-1 h-1. Extended X-ray absorption fine structure (EXAFS) measurement and density functional theory (DFT) calculation reveal the Pd-N1C3 sites from Pd-ISAS/CN efficiently boost the reactivity for semi-hydrogenation of acetylene. This work will bring inspiration to rationally design noble-metal-based ISAS catalysts derived from COF materials and boost catalytic performance by optimizing the coordination environment of catalytic sites.

The Prognostic Significance of C-Reactive Protein to Albumin Ratio in Newly Diagnosed Acute Myeloid Leukaemia Patients.

BACKGROUND: The ratio of C-reactive protein to albumin (CAR) is an inflammatory marker that has been demonstrated to be a simple and reliable prognostic factor in several solid tumours and chronic lymphocytic leukaemia (CLL). However, no studies have investigated the prognostic value of the CAR in patients with acute myeloid leukaemia (AML). OBJECTIVES AND METHODS: We retrospectively analysed 212 newly diagnosed non-M3 AML patients. Using the receiver operating characteristic curve (ROC) method, the optimal cut-off value for CAR was determined. We investigated the correlations of the pretreatment CAR levels with clinical characteristics, treatment response of induction chemotherapy, overall survival (OS) and event-free survival (EFS). We also assessed the prognostic value of the CAR compared with other inflammation-based prognostic parameters by the area under the curve (AUC). RESULTS: According to the ROC curve, the optimal cut-off value of CAR was 1.015. CAR was associated with age, C-reactive protein (CRP) levels, albumin levels, ferritin levels, bone marrow blast percentage, French-American-British (FAB) classification, immunophenotype and 2017 European Leukemia Net (2017 ELN) risk stratification. Importantly, we found that high CAR was a powerful indicator of a lower complete remission (CR) rate (p<0.001), worse OS (p<0.001) and worse EFS (p<0.001). Subgroup analysis showed that a high CAR was associated with shorter OS and EFS in patients with intermediate risk stratification or those aged ≤65 years or those without haematopoietic stem cell transplantation (HSCT). In the multivariate analysis, the CAR was an independent prognostic factor for OS and EFS. Furthermore, the predictive value of CAR for OS is superior to that of CRP, albumin and GPS in de novo AML patients aged ≤65 years old. CONCLUSION: CAR is a simple and effective prognostic marker in patients with AML. It could be an additional prognostic factor that help further precise the current risk stratification of non-M3 AML, particularly for patients in intermediate risk stratification and those aged ≤65 years and those who did not undergo HSCT.

Predictive factors for differentiating thrombohemorrhagic disorders in high-risk acute promyelocytic leukemia.

INTRODUCTION: Acute promyelocytic leukemia (APL) is often accompanied by potentially fatal coagulopathy, especially in high-risk APL. Bleeding, particularly severe bleeding is the leading cause of early death (ED). Meanwhile, thrombosis, the other major coagulopathic complication, is being increasingly recognized. However, predictors of thrombohemorrhagic disorders are still not well investigated. MATERIALS AND METHODS: In this study, we retrospectively studied 83 patients with high-risk APL and categorized them into severe bleeding, thrombosis and no evident events groups. RESULTS: Severe bleeding was observed in 15 patients, nearly half of whom died of hemorrhage, while thrombosis was observed in 12 patients. Risk factor analysis showed that high WBC (>58.76 × 109/L) (p = 0.001) and prolonged PT (>17.7 s) (p = 0.015) could be independent predictors for severe bleeding, while high WBC/D-dimer>5.12 (p = 0.002) and low D-dimer/FIB<5.14 (p = 0.03) could be independent predictors for thrombosis in high-risk APL patients. Moreover, there are significant differences in WBC/D-dimer and D-dimer/FIB between DIC and Non-DIC groups (p < 0.001). Notably, we found that the WBC/D-dimer was dramatically higher in the thrombotic group than in the other two groups at the time of admission or during the first week of induction therapy. CONCLUSIONS: High WBC and prolonged PT could predict severe bleeding in high-risk APL patients, while high WBC/D-dimer and low D-dimer/FIB could be independent predictors for thrombosis. For high-risk APL, WBC/D-dimer and D-dimer/FIB are also beneficial in the diagnosis of DIC. WBC/D-dimer might help early identification of thrombosis at the time of admission or during the first week of induction therapy.

Absolute Circulating Leukemic Cells as a Risk Factor for Early Bleeding Events in Patients with Non-High-Risk Acute Promyelocytic Leukemia.

BACKGROUND: Hemorrhagic complications are the most common cause of early death in patients with APL and remain a major challenge in the management of APL. Early fatal bleeding events occur not only in high-risk but also in non-high-risk acute promyelocytic leukemia (APL) patients with normal or low WBC counts. OBJECTIVES AND METHODS: To demonstrate the role of the absolute number of circulating leukemic cells in early bleeding events in APL patients. Clinical and laboratory characteristics of 149 patients newly diagnosed with APL were obtained from medical records and retrospectively investigated. RESULTS: In this study, circulating absolute leukemic cells were positively correlated with the WBC count (r=0.9813, p<0.001) in all patients with APL, and importantly, they were strongly associated with significant bleeding events in non-high-risk patients. Multivariate logistic regression analysis showed that the absolute number of leukemia cells was an independent risk factor for significant bleeding events in APL patients. A cut-off value of 2.59×109/L for circulating leukemic cells to predict significant bleeding events in APL patients was obtained by ROC curve analysis. We further confirmed that the significant bleeding rate of patients with non-high-risk APL was statistically increased when the absolute number of circulating leukemic cells was ≥2.59×109/L. CONCLUSION: Circulating leukemic cell content has great clinical value for predicting early bleeding events in APL patients, especially in non-high-risk APL.

Acute promyelocytic leukemia with myelofibrosis: A case report and literature review.

RATIONALE: Acute promyelocytic leukemia (APL) with myelofibrosis (MF) is rare, and only 14 cases have been reported in the literature to date. PATIENT CONCERNS: A 42-year-old woman was admitted to the hospital with easy bruising and excessive bleeding. With the remission of the primary disease during treatment, the degree of fibrosis did not decrease, but worsened progressively. DIAGNOSIS: The woman was diagnosed with acute promyelocytic leukemia with secondary myelofibrosis. INTERVENTIONS: All-trans retinoic acid (ATRA) was discontinued after 6 months of complete remission of APL. Arsenic trioxide (ATO) was discontinued because of supraventricular tachycardia 9 months after complete remission of APL. OUTCOMES: After withdrawal of ATRA for 2 months, the degree of fibrosis was significantly alleviated, and after withdrawal of ATRA for 8 months and ATO for 5 months, bone marrow biopsy showed no reticular fiber deposition. LESSONS: In this case report and review of an additional 14 cases of APL with MF, we highlighted the importance of the degree of MF to be evaluated by bone marrow biopsy at the time of bone marrow aspiration when APL is suspected. If MF is present, the type of MF should be determined in a timely manner, and appropriate intervention measures should be taken accordingly.

Au@Pt Nanotubes within CoZn-Based Metal-Organic Framework for Highly Efficient Semi-hydrogenation of Acetylene.

Designing nanocatalysts with synergetic functional component is a desirable strategy to achieve both high activity and selectivity for industrially important hydrogenation reaction. Herein, we fabricated a core-shell hollow Au@Pt NTs@ZIFs (ZIF, zeolitic imidazolate framework; NT, nanotube) nanocomposite as highly efficient catalysts for semi-hydrogenation of acetylene. Hollow Au@Pt NTs were synthesized by epitaxial growth of Pt shell on Au nanorods followed with oxidative etching of Au@Pt nanorod. The obtained hollow Au@Pt NTs were then homogeneously encapsulated within ZIFs through in situ crystallization. By combining the high activity of bimetallic nanotube and gas enrichment property of porous metal-organic frameworks, hollow Au@Pt NT@ZIF catalyst was demonstrated to show superior catalytic performance for the semi-hydrogenation of acetylene, in terms of both selectivity and activity, over those of monometallic Au and solid bimetal nanorod@ZIF counterparts. This catalysts design idea is believed to be inspirable for the development of highly efficient nanocomposite catalysts.

Atomically dispersed Fe atoms anchored on COF-derived N-doped carbon nanospheres as efficient multi-functional catalysts.

Non-noble metal isolated single atom site (ISAS) catalysts have attracted much attention due to their low cost, ultimate atom efficiency and outstanding catalytic performance. Herein, atomically dispersed Fe atoms are prepared by a covalent organic framework (COF)-absorption-pyrolysis strategy. The obtained Fe ISASs anchored on COF-derived N-doped carbon nanospheres (Fe-ISAS/CN) served as a multi-functional catalyst in electro-catalysis and organic catalysis, exhibiting better catalytic performance than commercial Pt/C for the ORR with good stability and methanol tolerance. Besides electro-catalysis, the Fe-ISAS/CN also showed outstanding catalytic performance in organic reactions, such as the selective oxidation of ethylbenzene to acetophenone and dehydrogenation of 1,2,3,4-tetrahydroquinoline with excellent reactivity, selectivity, stability and recyclability. Co and Ni ISAS materials can also be prepared by this method, suggesting that it is a general strategy to obtain metal ISAS catalysts. This work will provide new insight into the design of COF-derived metal ISAS multi-functional catalysts for electro-catalysis and organic reactions using rationally designed synthetic routes and the optimized structure of substrates.

Direct observation of noble metal nanoparticles transforming to thermally stable single atoms.

Single noble metal atoms and ultrafine metal clusters catalysts tend to sinter into aggregated particles at elevated temperatures, driven by the decrease of metal surface free energy. Herein, we report an unexpected phenomenon that noble metal nanoparticles (Pd, Pt, Au-NPs) can be transformed to thermally stable single atoms (Pd, Pt, Au-SAs) above 900 °C in an inert atmosphere. The atomic dispersion of metal single atoms was confirmed by aberration-corrected scanning transmission electron microscopy and X-ray absorption fine structures. The dynamic process was recorded by in situ environmental transmission electron microscopy, which showed competing sintering and atomization processes during NP-to-SA conversion. Further, density functional theory calculations revealed that high-temperature NP-to-SA conversion was driven by the formation of the more thermodynamically stable Pd-N4 structure when mobile Pd atoms were captured on the defects of nitrogen-doped carbon. The thermally stable single atoms (Pd-SAs) exhibited even better activity and selectivity than nanoparticles (Pd-NPs) for semi-hydrogenation of acetylene.