Summary
Transnasal humidified rapid‐insufflation ventilatory exchange (THRIVE) can prolong apnoea time in adults. Therefore, THRIVE used for pre‐oxygenation in rapid sequence induction of anaesthesia ...could extend safe apnoea time during prolonged laryngoscopy and intubation. In this randomised controlled trial, we compared the lowest peripheral oxygen saturation (SpO2) during intubation when pre‐oxygenating with either traditional facemask or THRIVE. Eighty adult patients, undergoing rapid sequence induction of anaesthesia for emergency surgery, were randomly allocated to pre‐oxygenation with 100% oxygen with facemask or with THRIVE. Median (IQR range) lowest SpO2 until 1 min after intubation was 99% (97–100 70–100%) for the facemask group vs. 99% (99–100 96–100%) for the THRIVE group (p = 0.097). Five patients (12.5%) desaturated below 93% when pre‐oxygenated with the facemask vs. none in the THRIVE group (p = 0.019). There were no differences in intubation time or apnoea time between the groups. Median intubation time was 51 (34–66 22–261) s in the facemask group vs. 48 (38–63 10–146) s in the THRIVE group (p = 0.99). Median apnoea time was 109 (86–142 37–291) s and 116 (92–146 63–249) s when using facemask and THRIVE, respectively (p = 0.49). No signs of regurgitation of gastric content were detected. The data on desaturation indicate potential benefits of oxygenation with THRIVE for rapid sequence induction compared with facemask pre‐oxygenation.
•Species concentrations were measured during n-heptane mixture oxidation.•Filtered natural emission of species (FNES) was used for species measurements.•FNESS provides greater spatial resolution than ...other methods.•Concentrations of CO, CO2 and H2O were measured during n-heptane mixture oxidation.•The tests were performed at pressure of 22 bar and temperature range of 710 to 784 K.•The measured data was compared with results of 0-D and 3-D numerical.
Quantitative species concentration measurements taken during hydrocarbon oxidation are critical for the development of kinetic mechanisms. Spectroscopic methodologies are often employed to take such measurements due to their unobtrusive nature. A new methodology for species concentration measurements, called the filtered natural emission of species (FNES), has been proposed as it provides greater spatial resolution and a broader range of viable test conditions than other spectroscopic methods, such as laser absorption spectroscopy (LAS). To validate these claims, the concentrations of CO, CO2 and H2O were measured during the oxidation of a lean, n-heptane mixture in a rapid compression machine using FNES. The mixture was tested at an average pressure of 22 bar in the temperature range between 710 and 784 K. The measured data was compared with results of 0-D and 3-D numerical models using multiple kinetic mechanisms and available data found in literature. The empirical data of this work agreed well with the peak concentration measurements reported in the literature; however, the FNES methodology was able to provide insight into combustion processes when inhomogeneities caused by flow or boundary layer effects existed due to its unique field-of-view. As such, elevated CO concentrations were observed after the peak concentration when using the FNES methodology. This observation was not reported in literature nor captured by the 0-D numerical models; however, the 3-D model was able to explain the phenomenon as the result of the temperature field near the wall. 3-D simulations are recommended for the benefit of future works. In addition, the measured species concentrations displayed a great sensitivity to temperature, which was a function of the detailed kinetic mechanisms. Different kinetic mechanisms were found to significantly alter the results of the measured concentrations. Kinetic mechanisms must be chosen with care for accurate modeling of temperature for use of species concentration measurements.
Recent combustion research has focused on low temperature combustion to meet engine emission regulations and to advance the development of low temperature homogenous compression ignition engines. ...Autoignition studies in this temperature regime are primarily performed by Rapid Compression Machines (RCMs) which are sensitive to the heat transfer characteristics of the experimental device. RCMs are widely used to measure autoignition data such as ignition delay and species concentration. Measured ignition delays from RCMs are typically reported at an adiabatic condition; however, this assumption may produce a systematic error in ignition delay measurement as heat transfer is observed to reduce the pressure and temperature during the autoignition process, e.g., a longer ignition delay has a greater pressure and temperature drops. RCMs are custom built and have unique design characteristics that affect the heat transfer during the autoignition process. In addition, depending on the diluent composition (e.g., helium versus nitrogen or argon), different heat transfer characteristics are expected. As a result, autoignition results at similar conditions may vary from facility to facility or depending on the used diluent. The dependency of the measured data on the used facility or diluent may produce uncertainty in the data which impact the development of high-fidelity combustion mechanisms. In this work, a new method is developed and utilized to eliminate heat transfer from the ignition delay data. To evaluate the new method, the autoignition of n-pentane mixtures in the low temperature regime were investigated using an RCM. To vary the heat transfer, the compression ratio of the RCM was changed and the ignition delays were measured at similar pressure and temperature conditions. The tests were performed at an equivalence ratio of approximately one and nitrogen and argon as diluents. By applying the new method, the effect of heat transfer on the ignition delays were eliminated successfully and ignition delays at adiabatic condition were determined. A detailed kinetic model of n-pentane was used to simulate the measured adiabatic ignition delay, which agreed well with the experimental data.
•A new mathematical methodology to measure the boundary layer thickness was used at high gas pressure and temperature.•The new methodology is based on the line-of-sight broadband natural infrared ...species emission.•Time-resolved emissions of carbon monoxide and carbon dioxide were measured.•Boundary layer thicknesses along two perpendicular surfaces were calculated.•Average transmissivity for two different sapphire optical accesses determined for three spectral ranges.
Boundary layer thickness measurements have been taken via spectroscopic methods in the past, but were traditionally limited to a single point of view due to the need of an excitation source (such as a laser) and a detector. A new optical technique that measures the broadband filtered natural emissions of species does not require an excitation source to measure the boundary layer and thus can be used in multiple perspectives. In this work, two mid-wavelength infrared cameras are used to determine the boundary layer thickness on two inside surfaces of a rapid compression machine based on the emission from a gaseous mixture of N2, CO and CO2. The experiments were performed at two different gas pressures of 5.1 and 9.9 bar, and with gas temperatures of approximately 666 and 669 K, respectively. The wavelength ranges of 4.35–4.55, 4.545–4.785 and 4.069–4.445 μm were used to determine the boundary layer thicknesses at the side and front optical access of the rapid compression machine.
There has been considerable progress in the area of fuel surrogate development to emulate gasoline fuels’ oxidation properties. The current paper aims to review the relevant hydrocarbon group ...components used for the formulation of gasoline surrogates, review specific gasoline surrogates reported in the literature, outlining their utility and deficiencies, and identify the future research needs in the area of gasoline surrogates and kinetics model.
The purpose of this study was to determine whether exposure to pulsed electromagnetic field (PEMF) would shorten the healing time of regenerate bone in a rabbit tibial distraction model. Beginning 1 ...day after surgery, mid-shaft tibial osteotomies, stabilized with external fixators, were distracted 0.25 mm twice daily for 21 days and received either no exposure (sham control) or 1 hour per day exposure to low-amplitude, low-frequency PEMF. Tibiae were tested for torsional strength after 9, 16, and 23 days post-distraction. PEMF-treated tibiae were significantly stronger than shams at all three time points. By 16 days post-distraction, the PEMF group had achieved biomechanical strength essentially equivalent to intact bone. Shams did not achieve normal biomechanical strength even after 23 days post-distraction. In this tibial distraction model, short daily PEMF exposures accelerated consolidation of regenerate bone. Clinical usefulness awaits testing.
Objective: Research has demonstrated that standardized and normreferenced sensory-motor measures have the ability to differentiate between healthy children and those with ADHD. The purpose of this ...study was to determine if a newer statistical technique, Boosted Tree Methodology, could differentiate between these groups and if it would achieve a better classification rate than logistic regression. Data Selection: Participants were 118 individuals diagnosed with ADHD (mean age = 12.4 years; SD = 5.5) and 118 healthy individuals (mean age = 12.6 years; SD = 5.6) who were matched by age and gender to the clinical sample. All participants were administered the Dean-Woodcock Sensory Motor Battery (DWSMB). Data Synthesis: Boosted Tree (BT) Analysis is a new statistical technique that improves upon Classification and Regression Tree analysis in that multiple decision trees are created with each subsequent decision tree drawing upon the previously fitted tree to improve prediction accuracy. The predictors were 35 scores from the DWSMB. Results of the analysis indicate that the BT method correctly predicted group membership for 96.2% of cases, compared with logistic regression, which accurately predicted group membership for only 72.5% of individuals. Conclusion: The results suggest that BT analysis is a promising new statistical technique for improving diagnostic classification rates when compared with more traditional methods. The most important predictors included measures of simultaneous tactile localization, auditory perception, and finger-to-nose tasks. The fact that the BT analysis was able to correctly classify individuals with ADHD at such a high rate is even more impressive when it is considered that only sensory-motor, and not cognitive, variables were considered.
Infection with Mycobacterium bovis was diagnosed in a small privately owned herd of Sika deer. After postmortem examination of a deer with progressive pulmonary disease, diagnosis of infection with M ...bovis was confirmed by bacteriologic culture. The 2 remaining deer in this herd were euthanatized, necropsied, and confirmed to be infected with M bovis. Three cats in contact with the deer were also euthanatized and necropsied. One of these cats had lesions suggestive of mycobacterial infection in the colon and mesenteric lymph nodes. Infection of this cat with M bovis was not confirmed by bacterial culture. Mycobacteriosis, infrequently encountered in clinical veterinary practice, may be confused with disease caused by other infective agents or neoplasia. The zoonotic potential of these bacteria and a recent increase in human tuberculosis warrants continued surveillance of companion and food animal populations for mycobacterial infection.
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