497 research outputs found
Nanoparticles usage tendencies in cementing systems for hydrocarbon wells
In oil and gas wells construction, one of the most critical processes is oil well cementing, whose function is to provide a zonal isolation between the pipe and sedimentary formation. For these reasons, one of the needs in the oil industry, specifically in cementing wells area, is the use of materials with high performance, in order to enhance the useful well's life, and reduce costs associated with their repair or losses due to failures in the cementing. Currently, the efforts in the area of high performance materials for oil wells cementing are focused on the development and use of Nanotechnology, science that study materials at nanoscale (10-9 m) and offers means to obtain substantial changes in the chemical, physical and mechanical properties, due to the increase of their surface that allows them to have a high reactivity. The cement is a complex mixture of inorganic chemical compounds, that contain mainly calcium silicates, aluminates (C3S, C2S, C3A), and gypsum. In the cementitious slurry preparation, the cement is put up in contact with water, producing the C-S-H gel as the main hydration product, with an amorphous initial structure that generate a mixture of solid final crystalline phases sometimes in the nanoscale sizes. This final structure is responsible for providing its mechanical properties. Therefore, their comprehension, modification and size control at nanoscale could enable the production of cementitious systems with improved properties. The present work shows a resume of studies done in PDVSA Intevep on the synthesis and potential use of nanoparticles in diverse faces of oil well cementing and their use as nano-additives. Those papers were focused mainly on the preparation and laboratory-scale study of colloidal solutions of silica nanoparticles (nano-SiO2), Alumina (nano- Al2O3), iron oxides (nano-Fe2O3) and ternary systems of calcium oxide-silica and aluminium (CaO-SiO2-Al2O3). Promising results were obtained on strength and cementing properties by adding nanosilica to the cement slurry formulations, and improvements on the mechanical properties, such as compressive strength at the order of 90% for 0.5% nanosilica concentrations based on weight of cement (BWOC)
Nanoparticles usage tendencies in cementing systems for hydrocarbon wells
In oil and gas wells construction, one of the most critical processes is oil well cementing, whose function is to provide a zonal isolation between the pipe and sedimentary formation. For these reasons, one of the needs in the oil industry, specifically in cementing wells area, is the use of materials with high performance, in order to enhance the useful well's life, and reduce costs associated with their repair or losses due to failures in the cementing. Currently, the efforts in the area of high performance materials for oil wells cementing are focused on the development and use of Nanotechnology, science that study materials at nanoscale (10-9 m) and offers means to obtain substantial changes in the chemical, physical and mechanical properties, due to the increase of their surface that allows them to have a high reactivity. The cement is a complex mixture of inorganic chemical compounds, that contain mainly calcium silicates, aluminates (C3S, C2S, C3A), and gypsum. In the cementitious slurry preparation, the cement is put up in contact with water, producing the C-S-H gel as the main hydration product, with an amorphous initial structure that generate a mixture of solid final crystalline phases sometimes in the nanoscale sizes. This final structure is responsible for providing its mechanical properties. Therefore, their comprehension, modification and size control at nanoscale could enable the production of cementitious systems with improved properties. The present work shows a resume of studies done in PDVSA Intevep on the synthesis and potential use of nanoparticles in diverse faces of oil well cementing and their use as nano-additives. Those papers were focused mainly on the preparation and laboratory-scale study of colloidal solutions of silica nanoparticles (nano-SiO2), Alumina (nano- Al2O3), iron oxides (nano-Fe2O3) and ternary systems of calcium oxide-silica and aluminium (CaO-SiO2-Al2O3). Promising results were obtained on strength and cementing properties by adding nanosilica to the cement slurry formulations, and improvements on the mechanical properties, such as compressive strength at the order of 90% for 0.5% nanosilica concentrations based on weight of cement (BWOC)
âBecause It Kind of Falls in Between, Doesnât It? Like an Acute Thing and a Chronicâ: the Psychological Experience of Anaphylaxis in Adulthood
Anaphylaxis is a serious, rare condition increasing in prevalence. This study explored the psychological experience of adult-onset anaphylaxis from patient, family and staff perspectives. Semi-structured interviews were conducted with twelve participants. Two global themes emerged from thematic analysis: âcontrollabilityâ (âan unknown and distressing experienceâ, âthe importance of control over triggersâ and âresponsibility but no control: the impact on othersâ) and âconflictâ (ârejecting illness identityâ, âminimisation of riskâ, âaccessing specialist care: running in slow motionâ and âpatient-centred versus service-centred careâ). Findings highlight the importance of perceived control and emphasise the presence of conflict in the experience of this complex, episodic condition
Collagen scaffold and lipoaspirate fluid - Derived stem cells for the treatment of cartilage defects in a Rabbit Model
The purpose of the present study was to assess and compare the chondroregenerative properties of PLA (processed lipoaspirate) and LAF (lipoaspirate fluid) cells, in a preclinical rabbit model of knee cartilage defect. The defects were repaired by a collagen I/III scaffold and added LAF-cells, PLA-cells or no cells, upon the study group. The results showed that collagen scaffolds seeded with LAF-derived stem cells appear to have slightly better activity and outcomes when compared to PLA-cells, in terms of cartilage regeneration
Serum Total Tryptase Level Confirms Itself as a More Reliable Marker of Mast Cells Burden in Mast Cell Leukaemia (Aleukaemic Variant)
Mast cell leukemia (MCL) is a very rare form of systemic mastocytosis (SM) with a short median survival of 6 months. We describe a case of a 65-year-old woman with aleukaemic variant of MCL with a very high serum total tryptase level of 2255âÎŒg/L at diagnosis, which occurred following an episode of hypotensive shock. She fulfilled the diagnostic criteria of SM, with a bone marrow smear infiltration of 50â60% of atypical mast cells (MCs). She tested negative for the KIT D816V mutation, without any sign of organ damage (no B- or C-findings) and only few mediator-related symptoms. She was treated with antihistamine alone and then with imatinib for the appearance of anemia. She maintained stable tryptase level and a very indolent clinical course for twenty-two months; then, she suddenly progressed to acute MCL with a serum tryptase level up to 12960âÎŒg/L. The patient died due to haemorrhagic diathesis twenty-four months after diagnosis. This clinical case maybe represents an example of the chronic form of mast cell leukemia, described as unpredictable disease, in which the serum total tryptase level has confirmed itself as a reliable marker of mast cells burden regardless of the presence of other signs or symptoms
Development of a concept and basis for the DEMO diagnostic and control system
An initial concept for the plasma diagnostic and control (D&C) system has been developed as part of European studies towards the development of a demonstration tokamak fusion reactor (DEMO). The main objective is to develop a feasible, integrated concept design of the DEMO D&C system that can provide reliable plasma control and high performance (electricity output) over extended periods of operation. While the fusion power is maximized when operating near to the operational limits of the tokamak, the reliability of operation typically improves when choosing parameters significantly distant from these limits. In addition to these conflicting requirements, the D&C development has to cope with strong adverse effects acting on all in vessel components on DEMO (harsh neutron environment, particle fluxes, temperatures, electromagnetic forces, etc.). Moreover, space allocation and plasma access are constrained by the needs for first wall integrity and optimization of tritium breeding. Taking into account these boundary conditions, the main DEMO plasma control issues have been formulated, and a list of diagnostic systems and channels needed for plasma control has been developed, which were selected for their robustness and the required coverage of control issues. For a validation and refinement of this concept, simulation tools are being refined and applied for equilibrium, kinetic and mode control studies
Acute ST-segment elevation myocardial infarction after amoxycillin-induced anaphylactic shock in a young adult with normal coronary arteries: a case report
BACKGROUND: Acute myocardial infarction (MI) following anaphylaxis is rare, especially in subjects with normal coronary arteries. The exact pathogenetic mechanism of MI in anaphylaxis remains unclear. CASE PRESENTATION: The case of a 32-year-old asthmatic male with systemic anaphylaxis, due to oral intake of 500 mg amoxycillin, complicated by acute ST-elevation MI is the subject of this report. Following admission to the local Health Center and almost simultaneously with the second dose of subcutaneous epinephrine (0.2 mg), the patient developed acute myocardial injury. Coronary arteriography, performed before discharge, showed no evidence of obstructive coronary artery disease. In vivo allergological evaluation disclosed strong sensitivity to amoxycillin and the minor (allergenic) determinants of penicillin. CONCLUSION: Acute ST-elevation MI is a rare but potential complication of anaphylactic reactions, even in young adults with normal coronary arteries. Coronary artery spasm appears to be the main causative mechanism of MI in the setting of "cardiac anaphylaxis". However, on top of the vasoactive reaction, a thrombotic occlusion, induced by mast cell-derived mediators and facilitated by prolonged hypotension, cannot be excluded as a possible contributory factor
Gag Mutations Strongly Contribute to HIV-1 Resistance to Protease Inhibitors in Highly Drug-Experienced Patients besides Compensating for Fitness Loss
Human immunodeficiency virus type 1 (HIV-1) resistance to protease inhibitors (PI) results from mutations in the viral protease (PR) that reduce PI binding but also decrease viral replicative capacity (RC). Additional mutations compensating for the RC loss subsequently accumulate within PR and in Gag substrate cleavage sites. We examined the respective contribution of mutations in PR and Gag to PI resistance and RC and their interdependence using a panel of HIV-1 molecular clones carrying different sequences from six patients who had failed multiple lines of treatment. Mutations in Gag strongly and directly contributed to PI resistance besides compensating for fitness loss. This effect was essentially carried by the C-terminal region of Gag (containing NC-SP2-p6) with little or no contribution from MA, CA, and SP1. The effect of Gag on resistance depended on the presence of cleavage site mutations A431V or I437V in NC-SP2-p6 and correlated with processing of the NC/SP2 cleavage site. By contrast, reverting the A431V or I437V mutation in these highly evolved sequences had little effect on RC. Mutations in the NC-SP2-p6 region of Gag can be dually selected as compensatory and as direct PI resistance mutations, with cleavage at the NC-SP2 site behaving as a rate-limiting step in PI resistance. Further compensatory mutations render viral RC independent of the A431V or I437V mutations while their effect on resistance persists
Purification and Characterization of Two New Allergens from the Venom of Vespa magnifica
Due to poor diagnostic facilities and a lack of medical alertness, allergy to Vespa wasps may be underestimated. Few allergens have been identified from Vespa wasps
Low percentage of clinically relevant pistachio nut and mango co-sensitisation in cashew nut sensitised children
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