Regulating the vacancies of nitrogen-doped carbon nanohorns for high-performance electromagnetic wave absorption.

Single-walled carbon nanohorns (SWCNHs), which are sealed on one side with a conical cap and can self-aggregate, are aggregates with spherical morphology ranging from 30 to 100 nm and include dahlia, bud, and seed structures. These SWCNHs are suitable for electromagnetic wave absorption (EMWA) due to their conductivity loss. However, conductivity loss, which is part of three primary loss mechanisms, leads to SWCNHs suffering from impedance mismatching and a narrow effective absorption bandwidth (EAB). In this work, the content of vacancy-type defects in "dahlia-like" nitrogen-doped single-walled carbon nanohorns (NSWCNHs) is regulated by dielectric barrier discharge (DBD) plasma with argon to adjust their polarization and impedance matching. The high-energy argon ions from the plasma impact the bonds between the carbon atoms and adsorbed oxygen, leading to the sputtering of oxygen atoms from the surface and resulting in an increase in surface disorder and defect content. Vacancy-type defects improved polarization loss and optimized impedance matching, leading to the satisfactory EMWA performance of NSWCNHs. The NSWCNHs exhibit an outstanding minimum reflection loss (RLmin) of -57.94 dB when subjected to argon DBD treatment for 5 minutes, achieving this remarkable result at a thickness of 1.9 mm. Additionally, the effective absorption bandwidth (EAB) can cover 4.78 GHz after a treatment period of 1 minute. These results suggest that NSWCNHs have great potential as high-efficiency EMWA materials and demonstrate a new approach for designing high-performance EMWA absorbers.

Big data analysis for Covid-19 in hospital information systems.

The COVID-19 pandemic has triggered a global public health crisis, affecting hundreds of countries. With the increasing number of infected cases, developing automated COVID-19 identification tools based on CT images can effectively assist clinical diagnosis and reduce the tedious workload of image interpretation. To expand the dataset for machine learning methods, it is necessary to aggregate cases from different medical systems to learn robust and generalizable models. This paper proposes a novel deep learning joint framework that can effectively handle heterogeneous datasets with distribution discrepancies for accurate COVID-19 identification. We address the cross-site domain shift by redesigning the COVID-Net's network architecture and learning strategy, and independent feature normalization in latent space to improve prediction accuracy and learning efficiency. Additionally, we propose using a contrastive training objective to enhance the domain invariance of semantic embeddings and boost classification performance on each dataset. We develop and evaluate our method with two large-scale public COVID-19 diagnosis datasets containing CT images. Extensive experiments show that our method consistently improves the performance both datasets, outperforming the original COVID-Net trained on each dataset by 13.27% and 15.15% in AUC respectively, also exceeding existing state-of-the-art multi-site learning methods.

Collateral effects of COVID-19 countermeasures on hepatitis E incidence pattern: a case study of china based on time series models.

BACKGROUND: There are abundant studies on COVID-19 but few on its impact on hepatitis E. We aimed to assess the effect of the COVID-19 countermeasures on the pattern of hepatitis E incidence and explore the application of time series models in analyzing this pattern. METHODS: Our pivotal idea was to fit a pre-COVID-19 model with data from before the COVID-19 outbreak and use the deviation between forecast values and actual values to reflect the effect of COVID-19 countermeasures. We analyzed the pattern of hepatitis E incidence in China from 2013 to 2018. We evaluated the fitting and forecasting capability of 3 methods before the COVID-19 outbreak. Furthermore, we employed these methods to construct pre-COVID-19 incidence models and compare post-COVID-19 forecasts with reality. RESULTS: Before the COVID-19 outbreak, the Chinese hepatitis E incidence pattern was overall stationary and seasonal, with a peak in March, a trough in October, and higher levels in winter and spring than in summer and autumn, annually. Nevertheless, post-COVID-19 forecasts from pre-COVID-19 models were extremely different from reality in sectional periods but congruous in others. CONCLUSIONS: Since the COVID-19 pandemic, the Chinese hepatitis E incidence pattern has altered substantially, and the incidence has greatly decreased. The effect of the COVID-19 countermeasures on the pattern of hepatitis E incidence was temporary. The incidence of hepatitis E was anticipated to gradually revert to its pre-COVID-19 pattern.

Simultaneous removal of Cr(â ¥) and tetracycline from wastewater by dielectric barrier discharge plasma coupled with TiO2/rGO/Cu2O composites: Performance and mechanism.

In this study, dielectric barrier discharge (DBD) plasma combined with titanium dioxide/reduced graphene oxide/copper oxide (TiO2/rGO/Cu2O) composites for simultaneous removal of hexavalent chromium (Cr(Ⅵ)) and tetracycline (TC) from wastewater were explored systematically. The TiO2/rGO/Cu2O composites were successfully prepared to improve the specific surface area and charge carrier separation rate. When Cr(Ⅵ) and TC coexist, the two pollutants have better removal efficiency without changing the initial pH. Moreover, the removal efficiency of Cr(Ⅵ) and TC could be further improved in the DBD-TiO2/rGO/Cu2O system, indicating that the TiO2/rGO/Cu2O composites also exhibited good synergistic effects with the DBD plasma. The mechanism exploration showed that the TiO2/rGO/Cu2O composite catalyst could be activated in DBD system to produce various active species by photocatalytic reaction, among which photo-generated electrons and •O2- could significantly enhance Cr(Ⅵ) reduction, while photo-generated holes and •OH could improve TC degradation. More importantly, the intermediate products obtained from TC degradation can be oxidized to •CO2- by photo-generated holes, which can also facilitate the reduction of Cr(Ⅵ). This study shows that DBD combined with TiO2/rGO/Cu2O composites are capable of simultaneous Cr(Ⅵ) reduction and TC degradation, which would provide novel ideas for practical wastewater remediation.

Regulating local molecular polarization of triazine-PDI based polymer for high-efficient photocatalytic coupling of benzylamine.

Designing a robust built-in electric field (BF) is a charming strategy for enhancing the separation and transportation of charges via introducing large π-conjugated molecules. However, it has flexible or semiflexible geometries, which significantly disorder the crystalline and deteriorated the built-in electric field. Here, a straightforward tactic for creating a cyano-functionalized smaller D (benzene) - A (triazine) units in PDI- triazine based polymer (PDIMB) to enhance intrinsic molecule dipole has been proposed. The density functional theory (DFT) calculation revealed that the modification of smaller D-A groups destroyed the π-localization of charges, which enhanced the molecular dipole and the BF for promoting the exciton dissociation and charge transfer. Moreover, it not only exposed number of active sites, but also enhanced the interfacial molecular interacting. Therefore, PDIMB-2 exhibits high activity (24.5 mmol g-1 h-1) and selectivity (>99%) for the photooxidation of benzylamine to N-benzylidenebenzylamine under mild conditions. Our work offers a potential and simple synthetic option for enhancing the built-in electric field of polymer.

Critical role of vascular peroxidase 1 in regulating endothelial nitric oxide synthase.

Vascular peroxidase 1 (VPO1) is a member of the peroxidase family which aggravates oxidative stress by producing hypochlorous acid (HOCl). Our previous study demonstrated that VPO1 plays a critical role in endothelial dysfunction through dimethylarginine dimethylaminohydrolase2 (DDAH2)/asymmetric Dimethylarginine (ADMA) pathway. Hereby we describe the regulatory role of VPO1 on endothelial nitric oxide synthase (eNOS) expression and activity in human umbilical vein endothelial cells (HUVECs). In HUVECs AngiotensinII (100nM) treatment reduced Nitric Oxide (NO) production, decreased eNOS expression and activity, which were reversed by VPO1 siRNA. Knockdown of VPO1 also attenuated ADMA production and eNOS uncoupling while enhancing phosphorylated ser1177 eNOS expression level. Furthermore, HOCl stimulation was shown to directly induce ADMA production and eNOS uncoupling, decrease phosphorylated ser1177 eNOS expression. It also significantly suppressed eNOS expression and activity together with NO production. Therefore, VPO1 plays a vital role in regulating eNOS expression and activity via hydrogen peroxide (H2O2)-VPO1-HOCl pathway.

The incidence of dentinal cracks during root canal preparations with reciprocating single-file and rotary-file systems: A meta-analysis.

As a dangerous factor in vertical root fracture, dentinal crack formation is often associated with root canal instruments. We conducted this meta-analysis to compare the influence of two types of nickel titanium (NiTi) instruments that have different movements (reciprocating single-file versus full-sequence rotary file systems) on dentinal cracks formation during root canal preparation. Searches were conducted in PubMed, ISI Web of Knowledge, Embase and Cochrane Library using a combination of keywords. Titles and abstracts of all articles were independently assessed by two reviewers in accordance with the predefined inclusion criteria. Relevant studies were acquired in full-text form. Data in these articles were independently extracted. A meta-analysis was conducted using Review Manager 5.3. The results showed that the WaveOne and Reciproc files with a reciprocating motion produced significantly fewer dentinal cracks than the conventional rotational ProTaper technique.

Involvement of vascular peroxidase 1 in angiotensin II-induced hypertrophy of H9c2 cells.

Oxidative stress has been implicated in cardiac hypertrophy and heart failure. Vascular peroxidase 1 (VPO1), a peroxidase in the cardiovascular system, uses the hydrogen peroxide (H2O2) derived from co-expressed NADPH oxidases (NOX) to produce hypochlorous acid (HOCl) and catalyze peroxidative reactions. Our previous studies showed that VPO1 contributes to the vascular smooth muscle cell proliferation and endothelial dysfunction in spontaneous hypertensive rats (SHRs); however, the role of VPO1 in cardiomyocytes hypertrophy is still uninvestigated. The present study was therefore undertaken to examine the role of VPO1 in the angiotensin II-induced cardiac hypertrophy, and the underlying mechanism by which VPO1 regulates the redox signaling. As compared to WKY rats, the SHRs exhibited increased myocyte cross sectional area, enhanced Nox2 and VPO1 expression level in cardiac tissue, and an increased Ang II level in plasma. In cultured H9c2 cell line, Ang II increased the hypertrophy-related gene (BNP/ANF) expression and the cellular surface area, which was attenuated by knocking down of VPO1 via VPO1 siRNA or pharmacological inhibition of NOX/VPO1 pathway. Moreover, the enhanced hypochlorous acid (HOCl) production and phosphorylation of ERK1/2 was suppressed by VPO1 knockdown. Furthermore, the protective role of VPO1 siRNA transfection on H9c2 cardiomyocytes hypertrophy was abrogated on the HOCl stimulation, and the phosphorylated ERK1/2 expression level was found also upregulated after HOCl stimulation. In conclusion, these results suggest that the Nox2/VPO1/HOCl/ERK1/2 redox signaling pathway was implicated in the pathogenesis of Ang II-induced cardiac hypertrophy.

Vascular peroxidase 1 up regulation by angiotensin II attenuates nitric oxide production through increasing asymmetrical dimethylarginine in HUVECs.

Asymmetric dimethylarginine (ADMA), the endogenous inhibitor of nitric oxide synthase, contributes to endothelial dysfunction and subsequent cardiovascular events including hypertension. Vascular peroxidase 1 (VPO1) is a novel heme-containing peroxidase that uses hydrogen peroxide (H2O2) generated from co-expressed nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to catalyze peroxidative reactions. Our previous study revealed a clear connection between VPO1 gene expression and endothelial dysfunction in spontaneously hypertensive rats. In the present study, we explored whether VPO1 participates in endothelial dysfunction during hypertension by increasing ADMA production. Spontaneously hypertensive rats displayed impaired endothelium-dependent relaxation, decreased eNOS expression and nitric oxide production, significantly increased VPO1 expression in both plasma and aorta tissue, and an increased ADMA level in plasma. In cultured endothelial cells, angiotensin II increased the ADMA level by inhibiting dimethylarginine dimethylaminohydrolase activity, which was inhibited by knockdown of VPO1 using small hairpin RNA. Moreover, the NADPH oxidase inhibitor and the hydrogen peroxide scavenger attenuated angiotensin II-mediated up-regulation of VPO1 and generation of hypochlorous acid. Furthermore, VPO1-derived hypochlorous acid suppressed recombinant dimethylarginine dimethylaminohydrolase activity and increased ADMA production. VPO1 plays a critical role in ADMA production via H2O2-VPO1-hypochlorous acid pathways, which may contribute to endothelial dysfunction in hypertension.

A novel fluorescence assay for inorganic pyrophosphatase based on modulated aggregation of graphene quantum dots.

A simple and highly sensitive fluorometric method has been developed for inorganic pyrophosphatase (PPase) activity detection based on the disaggregation and aggregation of graphene quantum dots (GQDs). Copper ions can trigger the severe aggregation of GQDs with rich carboxyl groups, which results in effective fluorescence quenching. While, with the addition of pyrophosphate (PPi), the quenched fluorescence is effectively recovered owing to the strong interaction between PPi and Cu(2+). Furthermore, under the catalytic hydrolysis of PPase, the complex of PPi-Cu(2+)-PPi is rapidly disassembled, and the fluorescence is re-quenched. This method is highly sensitive and selective for PPase detection, with a linear correlation between the fluorescence intensity and the PPase concentration in the range from 1 to 200 mU mL(-1) with a detection limit down to 1 mU mL(-1) (S/N = 3). Additionally, the inhibition effect of NaF on the PPase activity is also studied. Thus, the proposed method may hold a potential application in the diagnosis of PPase-related diseases and screening of PPase inhibitors, to evaluate the function and inhibition of PPase in biological systems.

The role of vascular peroxidase 1 in ox-LDL-induced vascular smooth muscle cell calcification.

Reactive oxygen species (ROS)-induced osteogenic differentiation of vascular smooth muscle cells (VSMCs) is associated with the pathogenesis of vascular calcification. Vascular peroxidase 1 (VPO1), a peroxidase in the cardiovascular system, utilizes the hydrogen peroxide (H2O2) produced by co-expressed NADPH oxidases to produce hypochlorous acid (HOCl) and catalyze peroxidative reactions. The aim of this study was to determine whether VPO1 plays a role in the osteogenic differentiation of VSMCs in the setting of the vascular calcification induced by oxidized low-density lipoprotein (ox-LDL). In cultured primary rat VSMCs, we observed that the expression of VPO1 was significantly increased in combination with increases in calcification, as demonstrated via increased mineralization, as well as increased alkaline phosphatase (ALP) activity and up-regulated runt-related transcription factor 2 (Runx2) expression in ox-LDL-treated cells. Ox-LDL-induced VSMC calcification and Runx2 expression were both inhibited by knockdown of VPO1 using a small interfering RNA or by an NADPH oxidase inhibitor. Moreover, the knockdown of VPO1 in VSMCs suppressed the production of HOCl and the phosphorylation of AKT, ERK and P38 MAPK. Furthermore, HOCl treatment facilitated the phosphorylation of AKT, ERK1/2 and P38 MAPK and the expression of Runx2, whereas LY294002 (a specific inhibitor of PI3K), U0126 (a specific inhibitor of ERK1/2) and SB203580 (a specific inhibitor of P38 MAPK) significantly attenuated the HOCl-induced up-regulation of Runx2. Collectively, these results demonstrated that VPO1 promotes ox-LDL-induced VSMC calcification via the VPO1/HOCl/PI3K/AKT, ERK1/2, and P38 MAPK/Runx2 signaling pathways.

Complementary charge trapping and ionic migration in resistive switching of rare-earth manganite TbMnO3.

Perovskite rare-earth manganites like TbMnO3 exhibit rich magnetic and electric phases, providing opportunities for next-generation multifunctional devices. Here, we report the nonvolatile bipolar switching of resistance and capacitance in TbMnO3 thin films grown on conducting Nb:SrTiO3 substrates. The device shows an ON/OFF resistance ratio of ∼1 × 104, and the resistive switching is accompanied by a frequency-dependent capacitance switching. Detailed analysis of the conduction mechanisms reveals that the migration of oxygen vacancies and the charge trapping/detrapping at the heterojunction interface play important and complementary roles in the switching behaviors. Our results suggest that both electronic and ionic processes should be considered in order to elucidate the conduction mechanisms and the switching behaviors in such heterostructures made of complex oxides.