167 research outputs found
Column-Spatial Correction Network for Remote Sensing Image Destriping
The stripe noise in the multispectral remote sensing images, possibly resulting from the instrument instability, slit contamination, and light interference, significantly degrades the imaging quality and impairs high-level visual tasks. The local consistency of homogeneous region in striped images is damaged because of the different gains and offsets of adjacent sensors regarding the same ground object, which leads to the structural characteristics of stripe noise. This can be characterized by the increased differences between columns in the remote sensing image. Therefore, the destriping can be viewed as a process of improving the local consistency of homogeneous region and the global uniformity of whole image. In recent years, convolutional neural network (CNN)-based models have been introduced to destriping tasks, and have achieved advanced results, relying on their powerful representation ability. Therefore, to effectively leverage both CNNs and the structural characteristics of stripe noise, we propose a multi-scaled column-spatial correction network (CSCNet) for remote sensing image destriping, in which the local structural characteristic of stripe noise and the global contextual information of the image are both explored at multiple feature scales. More specifically, the column-based correction module (CCM) and spatial-based correction module (SCM) were designed to improve the local consistency and global uniformity from the perspectives of column correction and full image correction, respectively. Moreover, a feature fusion module based on the channel attention mechanism was created to obtain discriminative features derived from different modules and scales. We compared the proposed model against both traditional and deep learning methods on simulated and real remote sensing images. The promising results indicate that CSCNet effectively removes image stripes and outperforms state-of-the-art methods in terms of qualitative and quantitative assessments
Interfacial Properties of Bilayer and Trilayer Graphene on Metal Substrates
One popular approach to prepare graphene is to grow them on transition metal
substrates via chemical vapor deposition. By using the density functional
theory with dispersion correction, we systematically investigate for the first
time the interfacial properties of bilayer (BLG) and trilayer graphene (TLG) on
metal substrates. Three categories of interfacial structures are revealed. The
adsorption of B(T)LG on Al, Ag, Cu, Au, and Pt substrates is a weak
physisorption, but a band gap can be opened. The adsorption of B(T)LG on Ti,
Ni, and Co substrates is a strong chemisorption, and a stacking-insensitive
band gap is opened for the two uncontacted layers of TLG. The adsorption of
B(T)LG on Pd substrate is a weaker chemisorption, with a band gap opened for
the uncontacted layers. This fundamental study also helps for B(T)LG device
study due to inevitable graphene/metal contact.Comment: 1 table, 8 figure
Ag-Decorated Fe 3
Well-dispersed Ag nanoparticles (NPs) are successfully decorated on Fe3O4@SiO2 nanorods (NRs) via a facile step-by-step strategy. This method involves coating α-Fe2O3 NRs with uniform silica layer, reduction in 10% H2/Ar atmosphere at 450°C to obtain Fe3O4@SiO2 NRs, and then depositing Ag NPs on the surface of Fe3O4@SiO2 NRs through a sonochemical step. It was found that the as-prepared Ag-decorated magnetic Fe3O4@SiO2 NRs (Ag-MNRs) exhibited a higher catalytic efficiency than bare Ag NPs in the degradation of organic dye and could be easily recovered by convenient magnetic separation, which show great application potential for environmental protection applications
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Aging-associated metabolic disorder induces Nox2 activation and oxidative damage of endothelial function
Oxidative stress attributable to the activation of a Nox2-containing NADPH oxidase is involved in the development
of vascular diseases and in aging. However, the mechanism of Nox2 activation in normal aging remains unclear.
In this study, we used age-matched wild-type (WT) and Nox2 knockout (KO) mice at 3–4 months (young); 11–12 months (middle-aged) and 21–22 months (aging) to investigate age-related metabolic disorders, Nox2 activation and endothelial dysfunction. Compared to young mice, middle-aged and aging WT mice had significant hyperglycaemia, hyperinsulinaemia, increased systemic oxidative stress and higher blood pressure. Endothelium-dependent vessel relaxation to acetylcholine was significantly impaired in WT aging aortas, and this was accompanied by increased Nox2 and ICAM-1 expressions, MAPK activation and decreased insulin receptor expression and signaling. However, these aging-associated disorders were significantly reduced or absent in Nox2KO aging mice. The effect of metabolic disorder on Nox2 activation and endothelial dysfunction was further confirmed using high-fat diet-induced obesity and insulin resistance in middle-aged WT mice treated with apocynin (a Nox2 inhibitor). In vitro experiments showed that in response to high glucose plus high insulin challenge, WT coronary microvascular endothelial cells increased significantly the levels of Nox2 expression, activation of stress signaling pathways and the cells were senescent, e.g. increased p53 and β–galactosidase activity. However,these changes were absent in Nox2KO cells. In conclusion, Nox2 activation in response to aging-associated hyperglycaemia and hyperinsulinaemia plays a key role in the oxidative damage of vascular function. Inhibition or knockout of Nox2 preserves endothelial function and improves global metabolism in old age
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Inhibition of endothelial Nox2 activation by LMH001 protects mice from angiotensin II-induced vascular oxidative stress, hypertension and aortic aneurysm
Endothelial oxidative stress and inflammation attributable to the activation of a Nox2-NADPH oxidase are key features of many cardiovascular diseases. Here, we report a novel small chemical compound (LMH001, MW=290.079), by blocking phosphorylated p47phox interaction with p22phox, inhibited effectively angiotensin II (AngII)-induced endothelial Nox2 activation and superoxide production at a small dose (IC50=0.25µM) without effect on peripheral leucocyte oxidative response to pathogens. The therapeutic potential of LMH001 was tested using a mouse model (C57BL/6J, 7-month-old) of AngII infusion (0.8mg/kg/d, 14 days)-induced vascular oxidative stress, hypertension and aortic aneurysm. Age-matched littermates of p47phox knockout mice were used as controls of Nox2 inhibition. LMH001 (2.5mg/kg/d, ip. once) showed no effect on control mice, but inhibited completely AngII infusion-induced excess ROS production in vital organs, hypertension, aortic walls inflammation and reduced incidences of aortic aneurysm. LMH001 effects on reducing vascular oxidative stress was due to its inhibition of Nox2 activation and was abrogated by knockout of p47phox. LMH001 has the potential to be developed as a novel drug candidate to treat oxidative stress-related cardiovascular diseases
Marital status and gender differences as key determinants of COVID-19 impact on well-being, job satisfaction and resilience in health care workers and staff working in academia in the UK during the first wave of the pandemic
BACKGROUND: The COVID-19 pandemic is an unprecedented global public health crisis that continues to exert immense pressure on healthcare and related professional staff and services. The impact on staff wellbeing is likely to be influenced by a combination of modifiable and non-modifiable factors. OBJECTIVES: The aim of this study is to evaluate the effect of the COVID-19 pandemic on the self-reported wellbeing, resilience, and job satisfaction of National Health Service (NHS) and university staff working in the field of healthcare and medical research. METHODS: We conducted a cross sectional survey of NHS and UK university staff throughout the COVID-19 pandemic between May-November 2020. The anonymous and voluntary survey was disseminated through social media platforms, and via e-mail to members of professional and medical bodies. The data was analysed using descriptive and regression (R) statistics. RESULTS: The enjoyment of work and satisfaction outside of work was significantly negatively impacted by the COVID-19 pandemic for all of staff groups independent of other variables. Furthermore, married women reporting significantly lower well-being than married men (P=0.028). Additionally, the well-being of single females was significantly lower than both married women and men (P=0.017 and P<0.0001, respectively). Gender differences were also found in satisfaction outside of work, with women reporting higher satisfaction than men before the COVID-19 pandemic (P=0.0002). CONCLUSION: Our study confirms that the enjoyment of work and general satisfaction of staff members has been significantly affected by the first wave of the COVID-19 pandemic. Interestingly, being married appears to be a protective factor for wellbeing and resilience but the effect may be reversed for life satisfaction outside work. Our survey highlights the critical need for further research to examine gender differences using a wider range of methods
Graphdiyne-metal contacts and graphdiyne transistors
Graphdiyne is prepared on metal surface, and making devices out of it also
inevitably involves contact with metals. Using density functional theory with
dispersion correction, we systematically studied for the first time the
interfacial properties of graphdiyne contacting with a series of metals (Al,
Ag, Cu, Au, Ir, Pt, Ni, and Pd). Graphdiyne is in an n-type Ohmic or
quasi-Ohmic contact with Al, Ag, and Cu, while it is in a Schottky contact with
Au (at source/drain interface), Pd, Pt, Ni, and Ir (at source/drain-channel
interface), with high Schottky barrier heights of 0.39, 0.21 (n-type), 0.30,
0.41, and 0.45 (p-type) eV, respectively. A graphdiyne field effect transistor
(FET) with Al electrodes is simulated by using quantum transport calculations.
This device exhibits an on-off ratio up to 104 and a very large on-state
current of 1.3 * 104 mA/mm in a 10 nm channel length. Thus, a new prospect is
opened up for graphdiyne in high performance nanoscale devices.Comment: 27 pages, 9 figure
Clinicopathological Features and Prognostic Evaluation of UBR5 in Liver Cancer Patients
Background: Typically, liver cancer patients are diagnosed at an advanced stage and have a poor prognosis. N-recognin 5 (UBR5), a component of the ubiquitin protein ligase E3, is involved in the genesis and progression of several types of cancer. As of yet, it is unknown what the exact biological function of UBR5 is in liver cancer.Methods: A Kaplan-Meier survival curve (OS) was used to examine the effect of UBR5 expression on overall survival based on the TCGA database. To determine the molecular functions of UBR5 in liver cancer, we used the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. A protein-protein interaction (PPI) network was established for the screening of UBR5-related proteins in liver cancer. Western blot analysis was used to determine the expression levels of UBR5 and YWHAZ (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta), and in order to detect cell proliferation, an MTT assay was used.Results: The expression of UBR5 in liver cancer patient samples is significantly higher than in adjacent normal tissues. A high level of UBR5 expression was associated with older patients, a higher tumor grade, lymph node metastasis, and poor survival. We discovered YWHAZ with high connectivity, and UBR5 expression correlated positively with YWHAZ expression (r = 0.83, p < 0.05). Furthermore, we found that elevated UBR5 levels directly correlated with YWHAZ overexpression, and that UBR5 promoted cell proliferation by affecting YWHAZ expression. Additionally, the TCGA databases confirmed that patients with liver cancer who expressed higher levels of YWHAZ had poorer outcomes.Conclusion: This suggests that UBR5 associated with YWHAZ may influence prognosis in patients with liver cancer, and that UBR5 may be a candidate treatment target for liver cancer. Therefore, UBR5 associated with YWHAZ may influence prognosis in patients with liver cancer, and UBR5 could serve as a potential target for liver cancer treatment
Research on Protection Scheme of DC Microgrid Integrated with Fault Current Limiting Control Technology
[Introduction] With the development of new loads, such as distributed power sources and electric vehicles, DC(Direct Current) microgrids have the advantages of fewer commutation links and lower system losses than AC(Alternating Current) microgrids, and have become the current research hotspot. Due to the small coverage of the DC microgrid and access to a large amount of distributed power sources, the fault current rises quickly with a large amplitude when inter-pole short-circuit fault occurs, making it difficult to achieve differential coordination with traditional overcurrent protection used in AC distribution networks and posing a great challenge to fault localization. [Method] Therefore, in response to the characteristics of fault current in DC microgrids, the method for designing overcurrent protection setting value based on the precise control value of fault current through the integration of current limiting and protection was proposed. Combined with the reasonable capacity design of each branch, it can easily achieve differential coordination and accurately locate faults. [Result] A corresponding DC microgrid model is built on the PSCAD/EMTDC simulation platform. The proposed protection scheme is simulated and verified, and the result shows that the scheme can correctly locate the fault point and quickly remove the fault. [Conclusion] The proposed protection scheme can ensure the selectivity of overcurrent, which verifies the rationality of the scheme
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