455 research outputs found

    Rational design of mesoporous gallium oxide and gallium-based mixed oxide catalysts.

    Get PDF
    In the present study, we report the synthesis of thermally stable mesoporous gallium oxide and novel gallium-niobium mixed oxides employing Evaporation Induced Self-Assembly (EISA), Self-Assembly Hydrothermal-Assisted (SAHA) and Self-Assembly Microwave-Assisted approaches. These methods offer the possibility to synthesize thermally stable mesoporous oxides with controlled morphological, textural and structural properties. EISA led to partially crystalline meso porous gallium oxide phases displaying unimodal pore size distribution in the ~2-5 nm range and surface areas as high as 300 m2/g. SAHA led to nanocrystalline mesoporous uniform micron-sized gallium oxide spheres (~0.3-6.5 11m) with narrow size distribution displaying cubic spinel type structure. These mesophases displayed surface areas as high as 220 m2/g and unimodal pore-size distribution in the 5-15 nm range. Microwave-assisted approach led to the formation of nanocrystalline mesoporous gallium oxide phases at low reaction temperature (l30°C) and short reaction times (~15-120 min). Novel semicrystalline mesoporous Gallium-Niobium mixed oxide phases were prepared via Self-Assembly Hydrothermal-Assisted (SAHA) method. This method led to the formation of uniform ~ 0.3-2 11m micron-sized mesoporous mixed gallium-niobium oxide spheres with narrow size distribution displaying surface areas as high as 360 m2/g and unimodal pore size distribution in the 3-6 nm range. Due to their high surface areas, tunability of pore sizes and their acidic nature these single phase and mixed mesoporous gallium-niobium oxides were employed as catalysts in the epoxidation of cyclooctene and isomerization of methyl oleate. For the epoxidation of cyclooctene to epoxycyclooctane carried out at 60°C the mesoporous gallium oxide displayed 100% selectivity towards epoxide with the conversion of cyclooctene in the 4 to 16% range. As the reaction temperature was increased to 80°C, an increase in the cyclooctene conversion was observed. The highest cyclooctene conversion observed was ~52% with a selectivity of 83% toward the epoxide. A clear correlation was observed between the cyclooctene conversion and gallium oxide particle size at both reaction conditions. Agglomerate size between 2-3 11m led to higher cyclooctene conversion, whereas the agglomerate sizes between 4.5-7.5 11m led to lower cyclooctene conversions. For the isomerisation of methyl oleate, highest conversion of 57% with the selectivity of 86% and yield of ~50% was observed over a sample with gallium-niobium composition of 0.3:0.7 wt%. The superior catalytic performance of the gallium-niobium mixed oxide was attributed to its high acidity, crystallinity and mesoporosity

    Review of Supercapacitive Performance of Metal Oxide Thin Film Synthesized by Chemical Route

    Get PDF
    Objective of this paper is synthesis of metal-oxide supported on conducting substrate by electrochemical deposition. According to this study analysis of metal oxide thin film were done for physico-chemical properties like pH, current density, specific capacitance Vs voltage, surface area, cycle stability and coulombic efficiency. In order to get efficient metal-oxide thin film for various metal-oxide. Finally, higher energy density materials with better stability in an actual operating condition can be obtained by chemical route

    Review of Metal Oxide Thin Film Based Supercapacitors

    Get PDF
    Metal oxide thin films based supercapacitors known for several decades and are those used as for storing the potential energy.Presently research had done on energy storage methods namely redox electrochemical capacitors, the electrochemical double layer capacitor,metal oxides and conducting polymers. Recently, many chemically deposited metal oxide thin film electrodes including MnO2, Co3O4, NiO, Fe3O4 etc. have been tested in supercapacitors. From this review data of metal oxide thin films proposed to play a major role in supercapacitor technolog

    What do we know about dynamic glucose-enhanced (DGE) MRI and how close is it to the clinics? Horizon 2020 GLINT consortium report

    Get PDF
    Cancer is one of the most devastating diseases that the world is currently facing, accounting for 10 million deaths in 2020 (WHO). In the last two decades, advanced medical imaging has played an ever more important role in the early detection of the disease, as it increases the chances of survival and the potential for full recovery. To date, dynamic glucose-enhanced (DGE) MRI using glucose-based chemical exchange saturation transfer (glucoCEST) has demonstrated the sensitivity to detect both D-glucose and glucose analogs, such as 3-oxy-methyl-D-glucose (3OMG) uptake in tumors. As one of the recent international efforts aiming at pushing the boundaries of translation of the DGE MRI technique into clinical practice, a multidisciplinary team of eight partners came together to form the "glucoCEST Imaging of Neoplastic Tumors (GLINT)" consortium, funded by the Horizon 2020 European Commission. This paper summarizes the progress made to date both by these groups and others in increasing our knowledge of the underlying mechanisms related to this technique as well as translating it into clinical practice

    GLINT: GlucoCEST in neoplastic tumors at 3 T—clinical results of GlucoCEST in gliomas

    Get PDF
    Objective: Clinical relevance of dynamic glucose enhanced (DGE) chemical exchange saturation transfer (CEST) imaging has mostly been demonstrated at ultra-high field (UHF) due to low effect size. Results of a cohort study at clinical field strength are shown herein. // Materials and methods: Motion and field inhomogeneity corrected T1ρ‐based DGE (DGE⍴) images were acquired before, during and after a D-glucose injection with 6.3 s temporal resolution to detect accumulation in the brain. Six glioma patients with clear blood–brain barrier (BBB) leakage, two glioma patients with suspected BBB leakage, and three glioma patients without BBB leakage were scanned at 3 T. // Results: In high-grade gliomas with BBB leakage, D-glucose uptake could be detected in the gadolinium (Gd) enhancing region as well as in the tumor necrosis with a maximum increase of ∆DGE⍴ around 0.25%, whereas unaffected white matter did not show any significant DGE⍴ increase. Glioma patients without Gd enhancement showed no detectable DGE⍴ effect within the tumor. // Conclusion: First application of DGE⍴ in a patient cohort shows an association between BBB leakage and DGE signal irrespective of the tumor grade. This indicates that glucoCEST corresponds more to the disruptions of BBB with Gd uptake than to the molecular tumor profile or tumor grading

    The complex TIE between macrophages and angiogenesis

    Get PDF
    Macrophages are primarily known as phagocytic immune cells, but they also play a role in diverse processes, such as morphogenesis, homeostasis and regeneration. In this review, we discuss the influence of macrophages on angiogenesis, the process of new blood vessel formation from the pre-existing vasculature. Macrophages play crucial roles at each step of the angiogenic cascade, starting from new blood vessel sprouting to the remodelling of the vascular plexus and vessel maturation. Macrophages form promising targets for both pro- and anti-angiogenic treatments. However, to target macrophages, we will first need to understand the mechanisms that control the functional plasticity of macrophages during each of the steps of the angiogenic cascade. Here, we review recent insights in this topic. Special attention will be given to the TIE2-expressing macrophage (TEM), which is a subtype of highly angiogenic macrophages that is able to influence angiogenesis via the angiopoietin-TIE pathway

    Interleukin-17D and Nrf2 mediate initial innate immune cell recruitment and restrict MCMV infection.

    Get PDF
    Innate immune cells quickly infiltrate the site of pathogen entry and not only stave off infection but also initiate antigen presentation and promote adaptive immunity. The recruitment of innate leukocytes has been well studied in the context of extracellular bacterial and fungal infection but less during viral infections. We have recently shown that the understudied cytokine Interleukin (IL)-17D can mediate neutrophil, natural killer (NK) cell and monocyte infiltration in sterile inflammation and cancer. Herein, we show that early immune cell accumulation at the peritoneal site of infection by mouse cytomegalovirus (MCMV) is mediated by IL-17D. Mice deficient in IL-17D or the transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), an inducer of IL-17D, featured an early decreased number of innate immune cells at the point of viral entry and were more susceptible to MCMV infection. Interestingly, we were able to artificially induce innate leukocyte infiltration by applying the Nrf2 activator tert-butylhydroquinone (tBHQ), which rendered mice less susceptible to MCMV infection. Our results implicate the Nrf2/IL-17D axis as a sensor of viral infection and suggest therapeutic benefit in boosting this pathway to promote innate antiviral responses

    Wnt5a stimulates chemotactic migration and chemokine production in human neutrophils

    Get PDF
    Wnt5a is a ligand that activates the noncanonical Wnt signaling pathways (??-catenin-independent pathways). Human neutrophils expressed several Wnt5a receptors, such as Frizzled 2, 5 and 8. Stimulation of human neutrophils with Wnt5a caused chemotactic migration and the production of two important chemokines, CXCL8 and CCL2. CCL2 production by Wnt5a was mediated by a pertussis toxin-sensitive G-protein-dependent pathway. Wnt5a also stimulated the phosphorylation of three mitogen-activated protein kinases (MAPKs: ERK, p38 MAPK and JNK) and Akt. Inhibition of ERK, p38 MAPK or JNK by specific inhibitors induced a dramatic reduction in Wnt5a-induced CCL2 production. Supernatant collected from lipopolysaccharide-stimulated macrophages induced neutrophil chemotaxis, which was significantly inhibited by anti-Wnt5a antibody. Our results suggested that Wnt5a may contribute to neutrophil recruitment, mediating the inflammation response.open4

    CCL2/MCP-I Genotype-Phenotype Relationship in Latent Tuberculosis Infection

    Get PDF
    Among the known biomarkers, chemokines, secreted by activated macrophages and T cells, attract groups of immune cells to the site of infection and may determine the clinical outcome. Association studies of CCL-2/MCP-1 -2518 A/G functional SNP linked to high and low phenotypes with tuberculosis disease susceptibility have shown conflicting results in tuberculosis. Some of these differences could be due the variability of latent infection and recent exposure in the control groups. We have therefore carried out a detailed analysis of CCL-2 genotype SNP -2518 (A/G transition) with plasma CCL-2 levels and related these levels to tuberculin skin test positivity in asymptomatic community controls with no known exposure to tuberculosis and in recently exposed household contacts of pulmonary tuberculosis patients. TST positivity was linked to higher concentrations of plasma CCL2 (Mann Whitney U test; p = 0.004) and was more marked when the G allele was present in TST+ asymptomatic controls (A/G; p = 0.01). Recent exposure also had a significant effect on CCL-2 levels and was linked to the G allele (p = 0.007). Therefore association studies for susceptibility or protection from disease should take into consideration the PPD status as well as recent exposure of the controls group used for comparison. Our results also suggest a role for CCL-2 in maintaining the integrity of granuloma in asymptomatic individuals with latent infection in high TB burden settings. Therefore additional studies into the role of CCL-2 in disease reactivation and progression are warranted

    The Critical Role of Notch Ligand Delta-like 1 in the Pathogenesis of Influenza A Virus (H1N1) Infection

    Get PDF
    Influenza A viral infections have been identified as the etiologic agents for historic pandemics, and contribute to the annual mortality associated with acute viral pneumonia. While both innate and acquired immunity are important in combating influenza virus infection, the mechanism connecting these arms of the immune system remains unknown. Recent data have indicated that the Notch system is an important bridge between antigen-presenting cells (APCs) and T cell communication circuits and plays a central role in driving the immune system to overcome disease. In the present study, we examine the role of Notch signaling during influenza H1N1 virus infection, focusing on APCs. We demonstrate here that macrophages, but not dendritic cells (DCs), increased Notch ligand Delta-like 1 (Dll1) expression following influenza virus challenge. Dll1 expression on macrophages was dependent on retinoic acid-inducible gene-I (RIG-I) induced type-I IFN pathway, and not on the TLR3-TRIF pathway. We also found that IFNα-Receptor knockout mice failed to induce Dll1 expression on lung macrophages and had enhanced mortality during influenza virus infection. Our results further showed that specific neutralization of Dll1 during influenza virus challenge induced higher mortality, impaired viral clearance, and decreased levels of IFN-γ. In addition, we blocked Notch signaling by using γ-secretase inhibitor (GSI), a Notch signaling inhibitor. Intranasal administration of GSI during influenza infection also led to higher mortality, and higher virus load with excessive inflammation and an impaired production of IFN-γ in lungs. Moreover, Dll1 expression on macrophages specifically regulates IFN-γ levels from CD4+and CD8+T cells, which are important for anti-viral immunity. Together, the results of this study show that Dll1 positively influences the development of anti-viral immunity, and may provide mechanistic approaches for modifying and controlling the immune response against influenza H1N1 virus infection
    corecore