1,991 research outputs found
Successful airway resuscitation and removal of a life-threatening subglottic foreign body in an infant: a case report
No full textAirway foreign body (FB) removal is challenging and a time-limited and lifesaving procedure. Herein, we report successful removal of a life-threatening FB in the subglottic airway in an infant by physically forcing the FB further into the distal airway to block one lung and save the other. A 12-month-old boy presented in the emergency department with choking. Upon arrival, his mental status was alert. However, respiratory failure rapidly progressed and respiratory arrest occurred. We attempted to move the FB distally by pushing the endotracheal tube as deep as possible and advancing the stylet. The patient was successfully resuscitated, and bronchoscopic FB removal was performed. The patient was discharged without respiratory or neurologic sequelae
Reactive processing and mechanical properties of ZrO2/NiAl intermetallic matrix composite
No full text10 volume% ZrO2 reinforced NiAl matrix composite(ZrO2/NiAl) was prepared by reactive hot-pressing of elemental powders. Mixtures of Ni and Al powders with reinforcing particles of partially stabilized ZrO2 have been ball-milled and hot pressed at 980 degrees C under 30 MPa. The hot-pressed billets were extruded at 1200 degrees C with an extrusion ratio of 20:2 into bars with 16mm in diameter. The tensile and compressive tests of extruded ZrO2/NiAl composite was conducted at temperature ranged 25-1000 degrees C with strain rate ranged 1.7x10(-5) - 8.3x10(-4) s(-1). The NiAl matrix showed B2 type single phase mixed with uniform distribution of ZrO2 particles added as reinforcement and Al2O3 particles included as impurities from the oxide layer of Al powders. The average size of ZrO2 reinforcement and Al2O3 were measured as about 1.1 mu m and 0.7 mu m, respectively. The hot pressed billets showed 94% density and the ZrO2/NiAl composite was fully densified up to 99% after hot extrusion. The ZrO2/NiAl composite exhibited considerable strengthening effect and showed an increase of yield strength up to 270% at temperature ranged 850-950 degrees C, The effective strengthening of the ZrO2/NiAl composite indicates a possibility to overcome the poor high temperature strength of NiAl intermetallic compounds needed for structural application above 850 degrees C
Clinical Implications of the Obstructive Pattern on Chest Radiography in Children Aged 3–59 Months With Severe Lower Respiratory Tract Infections
No full textObjectives: To investigate the clinical implications of the obstructive pattern on plain chest radiography, defined as peribronchial cuffing or hyperinflation, in young children with severe lower respiratory tract infections (LRTIs). Methods: We reviewed all children aged 3‒59 months with LRTIs who underwent radiography and polymerase chain reaction in a Korean emergency department from 2016 through 2020. The radiographs were read as consolidation, peribronchial cuffing, or hyperinflation, with each interrater reliability computed. As per the obstructive pattern, we compared their clinical features, therapeutic interventions, outcomes, and microbiology. Results: Among 599 children with LRTIs, 465 were enrolled, of whom 98 (21.1%) had consolidation (κ = 0.60; 95% confidence interval, 0.50‒0.70), and 367 (78.9%) had peribronchial cuffing (0.55; 0.46‒0.65) or hyperinflation (0.59; 0.52‒0.67). The obstructive pattern was significantly associated with more frequent wheezing (obstructive, 28.6% vs. consolidation, 10.2%) and the use of inhaled albuterol or systemic steroids (39.0% vs. 23.5%), and lower median values or frequencies of age (22.0 vs. 35.0 months), crackle or diminished breath sound (42.0% vs. 61.2%), C-reactive protein (1.4 vs. 2.9 mg/dL), antibiotic therapy (72.2% vs. 93.9%), length of hospital stay (4.0 vs 5.0 days), fever lasting 3 days or longer (7.9% vs. 29.6%), and complications (0.5% vs. 9.2%). Microbiologically, viruses, such as respiratory syncytial virus, were more frequently detected in children with the obstructive pattern or at a younger age. Conclusions: This study confirms an association of the obstructive pattern on radiography with viral infection and inflammatory airway obstruction-relieving therapy in young children with severe LRTIs
The role of Umkhonto we Sizwe (MK) in the national liberation struggle in South Africa with reference to the rural far northern Transvaal, 1976-1990
No full textIncludes bibliographical references (leaves 250-275)
Experiencing the armed struggle : the Soweto generation and after
No full textIncludes bibliographical references (p. 354-369).This study explores the experiences of the rank-and-file soldiers of Umkhonto we Sizwe and the Azanian People's Liberation Anny. Extensive interviews by the author and other researchers reveal the voices of the soldiers themselves. The African National Congress and Pan African Congress archives at the University of the Western Cape and the University of Fort Hare supplement and verify these oral testimonies, as do some published sources. Most previously published materials about the armed struggle against apartheid have already focused on diplomacy, strategy and tactics, operations, leadership, and human rights abuses to the neglect of the soldiers' actual experiences. This study complements these with significant new oral history materials from the Soweto generation of soldiers and their successors. When dealing with MK, many authors have documented issues of the camp structure in Angola, and operations inside South Africa, so much of this detail is only addressed briefly, leaving space to explore the soldiers' experiences. In the case of APLA, very little has been written on its history, and more detail is provided on these subjects. This study therefore deals with the soldiers' politicisation and motivation for joining the armed struggle, their experiences in leaving South Africa and training in exile, the crises in exile which limited their effectiveness for a time, their return to fight in South Africa, and their difficulties in the "new" South Africa. These materials reveal that vast problems remain facing these veterans of the struggle against apartheid, and that they have the potential, if properly supported and employed, to contribute substantially to the development of present day South Africa. Conversely, if their neglect continues, they also have the potential to bring vast harm to the country. Further use of the investigative tools of oral history, especially if extended to the former soldiers' vernacular languages, is necessary to augment the history of South Africa, and these soldiers' contributions
SnO2 nanostructures synthesized on Co substrates
No full textThis study reported the fabrication of tin oxide (SnO2) nanostructures on Co-coated Si substrates by the thermal heating of Sn powders. The microstructures and morphologies of the resultant nanostructures were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and scanning electron microscopy (SEM). The product mainly comprised the tangled nanowires with average diameters in the range of 50-180 nm. The nanostructures were single-crystalline rutile structure of SnO2. The PL measurement with the Gaussian fitting exhibited visible light emission bands centered at 576 nm and 638 nm, respectively. We have discussed the possible growth mechanism of the nanostructures
Dawn Aerospace Mk-III Spaceplane Aerothermodynamic Analysis
No full textDawn Aerospace is developing a horizontal take-off and landing two stage to orbit partially-reusable launcher concept. The re-usable first stage spaceplane operates on a return to launch site trajectory and integrates into the existing airspace, flying as an UAV. For any re-entry vehicle the design needs to account for aerothermodynamic behaviour around the vehicle, to ensure the structure can survive the re-entry temperatures. The unique mission of the Mk-III means the thermal design considerations are unique and provide a new engineering challenge and research topic. This thesis investigates the aerothermodynamic behaviour of the Mk-III flow and structure. A loosely coupled model was created for this purpose, which couples engineering methods to predict the aerothermodynamics and the thermal behaviour of the structure. The coupling is done by transferring the external skin temperature and convective heat flux between the two simulations. The primary research question for this thesis is “What thermal protection systems have potential to be implemented on the Dawn Aerospace Mk-III spaceplane for a range of different design trajectories.” Two thermal protection systems (TPS) and material choices have been identified as potential solutions. The first is a fully titanium structure, which can handle the temperature experienced by the Mk-III for all trajectories at every point along the vehicle. The second is a combined titanium and BMI CF structure with an insulation layer on the BMI CF. The titanium is required for the temperatures experienced on the vehicle’s leading edges, while the BMI CF has been identified as suitable in areas away from the leading edge if protected by an insulation TPS. A benefit this option produces is that the insulation layer can be changed in thickness to lighten the vehicle for lower design trajectories, therefore creating different vehicles for different trajectories. However, combining a metal with a composite could pose manufacturing issues such as cost for different manufacturing processes and joining problems. This thesis could not properly trade-off between these two options due to it being outside the scope of this thesis and due to limitations in detailed structural knowledge. These two material choices were chosen from four materials analysed in the thesis and four different TPS. Other TPS were not suitable at decreasing the structural temperature for the Mk-III mission or had an unjustifiable weight penalty. The other material choices would have been suitable in certain situations but were heavier than the current proposed options and might have required a TPS. This thesis provides valuable insight in what suitable material and TPS choices could be for the Mk-III mission. It also shows that for any future material and TPS choice to be made, a comprehensive structural analysis is required. Mass is a key trade-off parameter between the two proposed solutions and a better structural analysis is required for any further trade-off.Aerospace Engineerin
On the determinant of Up on Mk(p,χ)
No full textIn this work, for p a prime, we compute the absolute value of the determinant of the UpUp-operator on the vector space Mk(p,χ)Mk(p,χ) of holomorphic modular forms of weight k and level Γ0(p)Γ0(p) with character χχ. As an implication, we confirm a number of conjectures of the second author
Changing dogma regarding the conformation of electron transferring menaquinone (MK)
No full text2017 Spring.Includes bibliographical references.Menaquinone-9 (MK-9) is the natural substrate containing a naphthoquinone and an isoprenyl side-chain with nine isoprene units that carry out the electron transfer for the Mycobacterium tuberculosis. We present studies aiming to understand the chemical and biochemical properties of hydrophobic MK molecules. Specifically, we are investigating the MK derivative with two isoprene units, MK-2, because it provides us with the base structure containing the naphthoquinone unit and the isoprene side-chain. Its synthesis is relatively simple because the precursors are commercially available, which allows for large scale preparation and detailed characterization of the molecular structure under different conditions. Using 1D and 2D 1H NMR studies we are establishing that MKs have different conformations depending on the specific environmental conditions. Similarly, we show using 1H-1H 2D NOESY NMR studies that the association of MK with the surfactant- water interface of reverse micelles, which is a model membrane system, modify the conformation of the menaquinone derivative. Finally, the redox potentials of MK-2 was measured in the three different solvents (DMSO, CH3CN and pyridine). We hypothesize that the redox potential is correlated to the conformational of the MK. We observed that the redox potentials varied with solvent. The observed folded structures of MK derivatives stand in contrast to the linear conformation shown in life science text books
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