1,721,598 research outputs found
State-of-the-art catalysts for CH4 steam reforming at low temperature
No full textThe methane steam reforming (MSR) technology is the oldest and the most vital route to convert CH4 into H2. The conventional process usually operates in a high temperature range of 973-1173 K due to the highly endothermic nature of the reforming reaction. Necessity to increase the energy efficiency leads to the development of processes operating at low temperature and of highly active and coke resistant catalysts. An active catalyst which can provide high reforming reaction rates at low temperature (<823 K) is therefore required. This work summarizes the latest developments on catalysts for methane steam reforming at low reaction temperature. Three major groups of materials are considered, nickel-based, noble metal-based and bimetallic catalysts. In each section the strategies proposed by several authors to enhance the performance of catalysts are discussed. An overview of the kinetic models developed for the description of the catalytic performance is also included. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
Entrapment of the sciatic nerve at the linea aspera: A case report and literature review
No full textNontraumatic, non-neoplastic sciatic nerve entrapment at the level of the thigh is extremely rare. In its course, in proximity of the linea aspera, the nerve is exposed to unexpected neuropathic syndromes associated with bone disorders
Precision Medicine in Inflammatory Bowel Diseases
Full text linkDuring the last decades, a better understanding of the mechanisms sustaining the pathogenic process in inflammatory bowel diseases (IBD) has contributed to expand the therapeutic armamentarium for patients with these disorders. Alongside with traditional therapies, monoclonal antibodies against tumor necrosis factor-alpha, the interleukin (IL)-12/IL-23 p40 subunit and the alpha 4 beta 7 integrin, and tofacitinib, a small molecule inhibiting intracellular pathways downstream to cytokine receptors, have entered into the clinic. However, these drugs are not effective in all patients and some responders can lose response over time. Such a therapeutic failure is, at least in part, dependent on the fact that, in IBD, the tissue damage is driven by simultaneous activation of multiple and distinct immune-inflammatory signals and the detrimental mucosal immune response changes over time even in the same patient. Therefore, personalized approaches aimed at identifying which patient should be treated with a specific drug at a precise time point are worth pursuing. A such approach has the advantage to improve efficacy of the drug and limit adverse reactions, thereby improving quality of the life of the patients and reducing costs. In this review, we summarize all the available evidence about the possible role of precision medicine in IBD
Smad7 and colorectal carcinogenesis: A double-edged sword
No full textColorectal carcinogenesis is a complex process in which many immune and non-immune cells and a huge number of mediators are involved. Among these latter factors, Smad7, an inhibitor of the transforming growth factor (TGF)-β1 signaling that has been involved in the amplification of the inflammatory process sustaining chronic intestinal inflammation, is supposed to make a valid contribution to the growth and survival of colorectal cancer (CRC) cells. Smad7 is over-expressed by tumoral cells in both sporadic CRC and colitis-associated CRC, where it sustains neoplastic processes through activation of either TGFβ-dependent or non-dependent pathways. Consistently, genome-wide association studies have identified single nucleotide polymorphisms of the Smad7 gene associated with CRC and shown that either amplification or deletion of the Smad7 gene associates with a poor prognosis or better outcome, respectively. On the other hand, there is evidence that over-expression of Smad7 in immune cells infiltrating the inflamed gut of patients with inflammatory bowel disease can elicit anti-tumor responses, with the down-stream effect of attenuating CRC cell growth. Taken together, these observations suggest a double role of Smad7 in colorectal carcinogenesis, which probably depends on the cell subset and the biological context analyzed. In this review, we summarize the available evidences about the role of Smad7 in both sporadic and colitis-associated CRC
Low temperature methane steam reforming: Catalytic activity and coke deposition study
No full textLow temperature steam reforming combined with hydrogen-selective membrane offers significant advantages in terms of energy conservation, reduction of GHG emissions and low cost operation. In this study, Ni supported on La/CeO 2-ZrO2 is evaluated under steam reforming at temperature <550 °C. The catalyst is highly active in steam reforming of methane and water gas shift reaction. Stability test at simulated biogas steam reforming was conducted and the catalyst showed extremely stable performance for long time on stream (90 h) and very low amount of carbonaceous deposits, as determined by TPO and TPH. The above characteristics demonstrate that this catalyst is a potential candidate for use in membrane reactors operating at low temperature for the one-step production of pure hydrogen. Copyright © 2013, AIDIC Servizi S.r.l
Catalyst development for steam reforming of methane and model biogas at low temperature
No full textLow temperature steam reforming (400-550°C) for the production of hydrogen offers significant advantages compared to the conventional process. The milder operating conditions lead to lower operation costs and cost of construction materials. Additionally, no CO shift reactor is required due to favorable temperature for the WGS reaction. In this work, we report the catalytic performance of Ni and Rh catalysts supported on La2O3-ZrO2 and La2O3-CeO2-ZrO2 for their application in a multifuel membrane reformer operating at low temperature. The performance of the catalysts is assessed in different operating conditions in methane steam reforming (GHSV, temperature, H2O/CH4ratio) as well as in reforming of model biogas. Stability tests were conducted up to 90h on stream (1bar and 7bar) and the tendency toward carbon formation was investigated. All catalysts were active in the reforming reactions at 400-550°C and the catalysts supported on La2O3-CeO2-ZrO2 showed superiority in activity and stability probably due to the presence of ceria in the support which contributes to the reforming rate and the resistance to carbonaceous deposits. Ni(10)CeZrLa exhibited remarkably stable performance with minimum amount of carbon formed after 90h (ca. 0.05wt%). TPO and TPH analysis of the carbonaceous deposits showed that the dominating type of carbon is highly reactive and can be easily removed by oxidation or hydrogenation at 500°C. This fact makes the catalyst even more promising for the proposed low temperature process, since the catalyst can be hydrogenated by using part of the H2 production stream without further heating of the reactor. © 2015 Elsevier B.V.
Endobronchial angioleiomyoma. Diagnostic difficulties of a rare lung neoplasm
Full text linkAngioleiomyoma is a benign soft tissue tumor which rarely develops in the respiratory tract. Here we report a case of a 51-year-old female with an angioleiomyoma developed in the left upper lobar bronchial branch and extended to the left main stem bronchus, causing non-specific symptoms, and not visible on the chest x-ray exam. The suspected diagnosis was established by High-Resolution Computed Tomography (HRCT) and confirmed by the histological evaluation of the endoscopically removed lesion
Dynamization-induced nanosolutes (DINS) in ultra-dilute solutions Analysis on homeopathic dilute capsules below and over the Avogadro’s number
No full textBACKGROUND: Homeopathy is a controversial topic. It is not clear what is the role of the succussion that should in-crease the efficacy of the homeopathic remedy. The primary aim is to verify whether could be the presence of nanosolutes when the dilution increases past the Avogrado's number and whether the succussion process increases the presence of nanosolutes. The secondary goal is to provide a rational model to develop theories on the mechanism of action of these solutions from a clinical standpoint.METHODS: Three different solution lines of highly diluted solutions have been made for each active ingredient: the first line was a non-shaken solution, the other two lines were shaken. They have run the following measurements: Fluores-cence, Absorption, Dynamic Light Scattering, Microbiological analysis.RESULTS: Fluorescence, light scattering and absorption, did not show any difference between the samples containing only water and samples derived from the solutions containing the active ingredients The shaken dilutions have shown a higher content in bacteria than the corresponding non-shaken (Biesse Bioscreen measurement: 0.000 ANOVA and Bon-ferroni). The bacteria are largely gram-positive at difference with those presence in the reference water solution, that are largely gram-negative.CONCLUSIONS: This study allows highlighting the presence of nanosolutes in high-diluted solutions Such nanosolutes are bacteria, which would bond with parts of parent substance in clusters. The succussion increases the number of nano -solutes. It is possible to hypothesize a mechanism of action of the homeopathic remedy on microbiotic basis.(Cite this article as: Tramontana A, Nicolai E, Sorge R, Gaziano R, Marino D, Monteleone G, et al. Dynamization-induced nanosolutes (DINS) in ultra-dilute solutions. Analysis on homeopathic dilute capsules below and over the Avogadro's number. Gazz Med Ital -Arch Sci Med 2022;181:271-7. DOI: 10.23736/S0393-3660.21.04735-5
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