Cross-Linked Polyphosphazene Hollow Nanosphere-Derived N/P-Doped Porous Carbon with Single Nonprecious Metal Atoms for the Oxygen Reduction Reaction.

Heteroatom-doped polymers or carbon nanospheres have attracted broad research interest. However, rational synthesis of these nanospheres with controllable properties is still a great challenge. Herein, we develop a template-free approach to construct cross-linked polyphosphazene nanospheres with tunable hollow structures. As comonomers, hexachlorocyclotriphosphazene provides N and P atoms, tannic acid can coordinate with metal ions, and the replaceable third comonomer can endow the materials with various properties. After carbonization, N/P-doped mesoporous carbon nanospheres were obtained with small particle size (≈50 nm) and high surface area (411.60 m2 g-1 ). Structural characterization confirmed uniform dispersion of the single atom transition metal sites (i.e., Co-N2 P2 ) with N and P dual coordination. Electrochemical measurements and theoretical simulations revealed the oxygen reduction reaction performance. This work provides a solution for fabricating diverse heteroatom-containing polymer nanospheres and their derived single metal atom doped carbon catalysts.

QEVIS: Multi-Grained Visualization of Distributed Query Execution.

Distributed query processing systems such as Apache Hive and Spark are widely-used in many organizations for large-scale data analytics. Analyzing and understanding the query execution process of these systems are daily routines for engineers and crucial for identifying performance problems, optimizing system configurations, and rectifying errors. However, existing visualization tools for distributed query execution are insufficient because (i) most of them (if not all) do not provide fine-grained visualization (i.e., the atomic task level), which can be crucial for understanding query performance and reasoning about the underlying execution anomalies, and (ii) they do not support proper linkages between system status and query execution, which makes it difficult to identify the causes of execution problems. To tackle these limitations, we propose QEVIS, which visualizes distributed query execution process with multiple views that focus on different granularities and complement each other. Specifically, we first devise a query logical plan layout algorithm to visualize the overall query execution progress compactly and clearly. We then propose two novel scoring methods to summarize the anomaly degrees of the jobs and machines during query execution, and visualize the anomaly scores intuitively, which allow users to easily identify the components that are worth paying attention to. Moreover, we devise a scatter plot-based task view to show a massive number of atomic tasks, where task distribution patterns are informative for execution problems. We also equip QEVIS with a suite of auxiliary views and interaction methods to support easy and effective cross-view exploration, which makes it convenient to track the causes of execution problems. QEVIS has been used in the production environment of our industry partner, and we present three use cases from real-world applications and user interview to demonstrate its effectiveness. QEVIS is open-source at https://github.com/DBGroup-SUSTech/QEVIS.

Lightweight Dual-Functional Segregated Nanocomposite Foams for Integrated Infrared Stealth and Absorption-Dominant Electromagnetic Interference Shielding.

Lightweight infrared stealth and absorption-dominant electromagnetic interference (EMI) shielding materials are highly desirable in areas of aerospace, weapons, military and wearable electronics. Herein, lightweight and high-efficiency dual-functional segregated nanocomposite foams with microcellular structures are developed for integrated infrared stealth and absorption-dominant EMI shielding via the efficient and scalable supercritical CO2 (SC-CO2) foaming combined with hydrogen bonding assembly and compression molding strategy. The obtained lightweight segregated nanocomposite foams exhibit superior infrared stealth performances benefitting from the synergistic effect of highly effective thermal insulation and low infrared emissivity, and outstanding absorption-dominant EMI shielding performances attributed to the synchronous construction of microcellular structures and segregated structures. Particularly, the segregated nanocomposite foams present a large radiation temperature reduction of 70.2 °C at the object temperature of 100 °C, and a significantly improved EM wave absorptivity/reflectivity (A/R) ratio of 2.15 at an ultralow Ti3C2Tx content of 1.7 vol%. Moreover, the segregated nanocomposite foams exhibit outstanding working reliability and stability upon dynamic compression cycles. The results demonstrate that the lightweight and high-efficiency dual-functional segregated nanocomposite foams have excellent potentials for infrared stealth and absorption-dominant EMI shielding applications in aerospace, weapons, military and wearable electronics.

Preparation and Properties of High-Temperature-Resistant, Lightweight, Flexible Polyimide Foams with Different Diamine Structures.

Polyimide foam (PIF) is a rising star in high-end applications such as aerospace thermal insulation and military sound absorption. However, the basic rule on molecular backbone design and uniform pore formation of PIF still need to be explored. In this work, polyester ammonium salt (PEAS) precursor powders are synthesized between alcoholysis ester of 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride (BTDE) and aromatic diamines with different chain flexibility and conformation symmetry. Then, a standard "stepwise heating" thermo-foaming approach is used to prepare PIF with comprehensive properties. A rational thermo-foaming program is designed based on in situ observation of pore formation during heating. The fabricated PIFs have uniform pore structure, and PIFBTDA-PDA shows the smallest size (147 µm) and narrow distribution. Interestingly, PIFBTDA-PDA also presents a balanced strain recovery rate (SR = 91%) and mechanical robustness (0.051 MPa at 25% strain) and its pore structure maintains regularity after 10 compression-recovery cycles, mainly due to high rigidity of the chains. Furthermore, all the PIFs possess lightweight feature (15-20 kg∙m-3), good heat resistance (Tg at 270-340 °C), thermal stability (T5% at 480-530 °C), thermal insulation properties (λ = 0.046-0.053 W∙m-1K-1 at 20 °C, λ = 0.078-0.089 W∙m-1K-1 at 200 °C), and excellent flame retardancy (LOI > 40%). The reported monomer-mediated pore-structure control strategy can provide guidelines for the preparation of high-performance PIF and its industrial applications.

Effects of sacubitril-valsartan on heart failure patients with mid-range ejection fractions: A systematic review and meta-analysis.

Aim: The effect of sacubitril-valsartan (ARNI) in heart failure (HF) patients with mid-range ejection fractions (HFmrEF) remains unclear. This study aimed to investigate the effects of ARNI in HFmrEF patients. Methods: From inception to 15 February 2022, articles were searched via PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Whip, and Wanfang databases. Left ventricular functions, indicators related to HF, quality of life score, 6-Minute Walk Test, total effective rate, mortality, readmission rate, and adverse events were the outcomes. Relative risk (RR), weighted mean difference (WMD), and 95% confidence interval (CI) were used to evaluate the outcomes. The heterogeneity test was conducted for each indicator and measured by I2 statistics. Subgroup analysis was performed regarding the type of study and duration of treatment. Results: Sixteen studies involving 1,937 patients were included in this study. Our results showed ARNI was likely to improve left ventricular function by increasing the left ventricular ejection fraction (LVEF) (WMD: 2.36, 95%CI: 1.09-3.62), stroke volume (WMD: 16.800, 95%CI: 11.385-22.215), and left ventricular short-axis shortening rate (WMD: 2.05, 95%CI: 0.25-3.86), decreasing left ventricular end-diastolic dimension (WMD: -2.48, 95%CI: -3.83 to -1.13), left atrial diameter (WMD: -2.23, 95%CI: -2.83 to -1.63), C-reactive protein level (WMD: -1.40, 95%CI: -2.62 to -0.18), and N-terminal-pro B-type natriuretic peptide level (WMD: -494.92, 95%CI: -641.34 to -348.50). ARNI has a higher total effective rate (RR: 1.15, 95%CI: 1.08-1.21), Kansas City cardiomyopathy questionnaire (WMD: 4.13, 95%CI: 3.46-4.81), and 6-Minute Walk Test (WMD: 51.35, 95%CI: 26.99-75.71) compared with angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB). In addition, ARNI decreased the readmission rate (RR: 0.54, 95%CI: 0.43-0.68) (all p < 0.05). Nevertheless, there were no significant differences in the adverse outcomes. Conclusion: This meta-analysis suggests ARNI may be an effective strategy with which to improve the left ventricular function, and quality of life, and reduce the readmission rate in HFmrEF patients. However, long-term clinical studies with large samples are still needed to further explore the efficacy and safety of ARNI compared with ACEI or ARB in the HFmrEF population.

rGO/MXene sandwich-structured film at spunlace non-woven fabric substrate: Application to EMI shielding and electrical heating.

Combining flexible reduced graphene oxide (rGO) with highlyelectrical conductive and flame retardant MXene to prepare electromagnetic interference (EMI) shielding composite film is a research hotspot. In this work, with a small amount of polyvinyl alcohol (PVA) used as the adhesive, rGO/MXene loaded on spunlace non-woven fabric (SNF) through a soaking-drying-reduction method to form a sandwich structure composite film (SNF covered with rGO/MXene nanosheets as the interlayer, and rGO/MXene thin films as the upper and lower layers). The related EMI shielding effectiveness (SE), electric heating performance and flame retardancy of the fabricated sandwich structure composite film have been investigated. When the mass ratio of rGO to MXene is 6:4 (named rGO/MXene-4), the average SET of the film can reach 55.81 dB in X-band with an absorption-dominant shielding. Applying a 4 V voltage to rGO/MXene-4 film, its surface temperature can exceed 110 °C within 10 s, which indicated the fabricated rGO/MXene-4 film can be applied as a high electromagnetic shielding electric heating device with outstanding flame retardancy.

Pim-3 alleviates lipopolysaccharide-stimulated AR42J pancreatic acinar cell injury via improving the inflammatory microenvironment.

Acute pancreatitis (AP) is a common acute abdominal disease characterized by pancreatic aseptic inflammation, with ~20% of patients progressing to severe AP (SAP) with a high mortality rate. The aim of this study was to explore the protective effects of Pim-3 proto-oncogene, serine/threonine kinase (Pim-3) on rat pancreatic acinar AR4-2J cells damaged by lipopolysaccharide (LPS). The recombinant plasmid p-enhanced green fluorescent protein (pEGFP)-N2/Pim-3 was transiently transfected into AR42J cells and the AR42J cells were then treated with 2 µg/ml LPS. Subsequently, the proliferation of AR42J cells was detected using MTT assay. The cell cycle progression and apoptosis rate of the AR42J cells were examined using flow cytometry. AR42J cell migration was assessed using wound healing assays. Additionally, RT-semi quantitative PCR and western blot analyses were used to detect the mRNA and protein expression levels, respectively, of Pim-3, interleukin (IL)-6, IL-1ß, tumor necrosis factor (TNF)-α, intercellular adhesion molecule (ICAM)-1 and Occludin in AR42J cells. The results revealed that proliferation of AR42J cells was significantly enhanced and cell apoptosis was markedly reduced in the pEGFP-N2/Pim-3 + LPS group. The proportion of AR42J cells in G1 phase in the pEGFP-N2/Pim-3 + LPS group was decreased, whereas the proportion of cells in the G2 and S phases was increased. The wound healing assays demonstrated that AR42J cell migration was significantly increased in the pEGFP-N2/Pim-3 + LPS group. Finally, the expression levels of IL-6, IL-1ß, TNF-α and ICAM-1 were significantly decreased in the pEGFP-N2/Pim-3 + LPS group, whereas the expression of Occludin was significantly increased. The present study demonstrated that raised expression levels of Pim-3 can protect AR42J cells from LPS-induced injury by modifying the inflammatory microenvironment, suggesting that Pim-3 may be a potential target for AP or SAP therapy.

Introduction of stereocomplex crystallites of PLA for the solid and microcellular poly(lactide)/poly(butylene adipate-co-terephthalate) blends.

Solid and microcellular poly(l-lactide)/poly(butylene adipate-co-terephthalate) (PLLA/PBAT) blends with or without poly(d-lactide) (PDLA) were prepared via melt blending and batch foaming process with supercritical carbon dioxide, respectively. The introduction of PDLA on the rheological properties, crystallization behavior and dynamic mechanical properties of the PLLA matrix were investigated. The formed PLA stereocomplex between PLLA and PDLA enhanced the storage modulus and complex viscosity of PLLA/PBAT blends efficiently. Interestingly, the addition of 5 wt% or 10 wt% PDLA in the PLLA/PBAT blends was unfavorable for the PLLA crystallization behavior. The potential reason can be sc-PLA crystallites acting as the physical crosslinking points, which constrained the molecular mobility of the PLLA matrix and even blocked the nucleating effect of PBAT domains. Both the enhanced melt strength and decreased crystallinity of the PLLA matrix are favorable for the cell nucleation and growth and the gas adsorption, respectively. The designed partially foaming of PLLA/PBAT with or without PDLA was carried out to investigate the foaming mechanism. The final cell morphology of PLLA/PBAT foams exhibited typical open-cell structure mainly attributed to the soft immiscible PBAT phase as separated domains. With further addition of PDLA in the PLLA/PBAT blends, the microcellular morphology exhibited decreased average cell size and increased cell density. The sc-PLA crystallites networks in the PLLA matrix acted as cell nucleating agents, which meanwhile resisted the force of cell growth and then prevented the cell collapse.