Clinical Characteristics of Chinese Pediatric Obstructive Sleep Apnea Hypopnea Syndrome

We aim to analyze the clinical characteristics of obstructive sleep apnea hypopnea syndrome (OSAHS) in children. Polysomnography (PSG) and nasopharynx lateral film were performed, and clinical data were collected in 469 children who came to the outpatient department due to "snoring during sleep with mouth opening breathing, hard breathing or suffocation". Among the enrolled children, 123 (22.6%) were diagnosed with OSAHS, with 70 were mild and 53 were moderate-severe. Percentage of adenoid hypertrophy was higher in OSAHS patients (p <0.01), instead of tonsil enlargement. The OSAHS children were agged 5 (4, 7). Compared with PS, the percentage of snoring, apnea, dyspnea, increased nocturia, and daytime sleepness were significsntly higher in moderate-severe patients (p <0.01). In OSAHS groups, AHI, ODI, Longest time of apnea were increased, while minimum SpO2 and mean SpO2 during sleep were decreased significantly (p <0.01) than PS. Time ratio of NREM1 was elevated in moderate-severe OSAHS patients (p <0.01). Time ratio of REM was elevated in mild patients(p <0.01). Compared with the preschoolers, the percentage of leg movement and sleepness were significsntly higher in school-agers (p <0.05). The youngers had higher time ratio of NREM3 and better sleep efficieny (p<0.01). However, AHI(p<0.05) and ODI(p<0.01) were higher in elder OSAHS significantly. Snoring (OR =5.745, p < 0.01), adenoid hypertrophy (OR =4.381, p < 0.01), apnea (OR =2.670, p < 0.001), dyspnea (OR =1.975, p < 0.01), and CRP (OR =1.172, p < 0.001) were independent risk factors for OSAHS. Conclusion AHI, ODI, Longest time of apnea, minimum SpO2 and mean SpO2 should be considered and analyzed simultaneously in diagnosis. The school-age OSAHS patients seems to more serious than the preschoolers. Snoring, apnea, dyspnea, adenoid hypertrophy, and CRP are risk factors for OSAHS.

Intraoperative Tilted Posteroanterior View for the Measurement of Distal Radius Articular Step-Off

The purpose of this study is to more accurately determine distal radius articular step-off in the posteroanterior (PA) view. A cadaveric forearm was osteotomized with varying amounts of articular displacement. A second osteotomy was made through the distal radius metaphysis to create four positions of tilt in the lateral plane (5° and 15° dorsal tilt; 5° and 15° volar tilt). Using fluoroscopy, the beam was positioned in the lateral plane from 25° volar to 20° dorsal, separated by 5° increments, obtaining modified PA images of the distal radius in its various configurations. The images were randomly evaluated for step-off by three hand surgeons in a blinded fashion. Statistical analysis was performed to determine the accuracy between estimated and actual step-off and was demonstrated to be greater when the PA view was parallel to the distal radius tilt in the lateral plane, for all four configurations of distal radius tilt. Data pertaining to the distal radius with 0 mm of step-off did not demonstrate the PA view, parallel to the distal radius tilt, to be superior than the PA views not parallel to the tilt; reaffirming that with anatomic reduction, any fluoroscopic image exhibits good alignment. This study confirms that the most accurate method of accessing PA step-off is to first determine the tilt of the radius on a lateral film and then align the beam in the PA plane to match this tilt.

Numerical Investigation of Film Cooling Enhancement Using an Upstream Sand-Dune-Shaped Ramp

Film cooling enhancement by incorporating an upstream sand-dune-shaped ramp (SDSR) to the film hole exit was numerically investigated on a flat plate under typical blowing ratios ranging from 0.5 to 1.5. Three heights of SDSRs were designed: 0.25D, 0.5D, and 0.75D. The results indicated that the upstream SDSR effectively controlled the near-wall primary flow and subsequent mutual interaction with the coolant jet, which was the main mechanism of the film cooling enhancement. First, a pair of anti-kidney vortices was formed at the trailing ridges of the SDSR, which helped suppress the kidney vortex pair due to the interaction between the coolant jet and the primary flow. Second, a weak separation and a low pressure zone were induced behind the backside of the SDSR, which caused the coolant jet to spread around the film cooling hole and improve the lateral film coverage. With respect to the baseline cylindrical film cooling holes, the effect of the upstream SDSR was distinct under different blowing ratios. Under a low blowing ratio, the upstream SDSR shortened the streetwise film layer coverage in the vicinity of the film hole centerline but increased the span-wise film layer coverage. A relatively optimal ramp height seemed to be 0.5D. Under a high blowing ratio, both the streamwise and span-wise film layer coverages improved in comparison with the baseline case. The film cooling effectiveness improved gradually with increasing ramp height.

Advanced Film Cooling Performance of a Y-Shaped Hole With Inner Crossflow

Film cooling performances of three film holes have been numerical researched in this paper, including a lateral inclined cylindrical hole, a fan-shaped hole and a y-shaped hole. The simulation is computed by the commercial software Fluent based on Reynolds Averaged Navier-Stokes (RANS) equations and realizable k-ε turbulence model with enhanced wall treatment. The y-shaped hole is a novel film hole developed from the lateral inclined cylindrical hole. With inner crossflow, the jet of the lateral inclined cylindrical hole performs to be two streams as a result of the helical motion in the hole. Accordingly, the hole exit was optimized with two expansions: one is expanded along the lateral inclined direction and the other is expanded along the mainstream flow direction. The lateral inclined cylindrical hole with two expansions at the exit is named the y-shaped hole. Compared to the fundamental lateral inclined cylindrical hole, the y-shaped hole has different counter-rotating vortices and much better film coverage. Experiments have been conducted to test the film cooling performance of the y-shaped hole. Compared to the lateral inclined cylindrical hole, much higher film cooling effectiveness has been measured in the y-shaped hole as a result of the enhanced lateral film coverage and the weakened film dissipation in the streamwise direction. The film performance of the y-shaped hole rises with the increase of the blowing ratio. At M = 2.0, the film of the y-shaped hole keeps close to the wall while the film of the lateral inclined cylindrical hole is completely lifted up, resulting in the increase of the area average film cooling effectiveness up to 128.7%.

Effect of spherical blockage configurations on film cooling

With increasing inlet temperature of gas turbines, turbine blades need to be effectively protected by using cooling technologies. However, the deposition from the fuel impurities and dust particles in the air is often found inside film holes, which results in partial hole blockage. In this paper, the deposition geometry is simplified as a rectangular channel, and the effect of three blockage ratios is investigated by using the computational fluid dynamics. In addition, water droplets are also released from the coolant inlet to provide a comparison of the results with and without mist injection. It is found that the lateral film cooling effectiveness is reduced with increasing blockage ratio. For all the cases with the blowing ratio 0.6, 1% mist injection provides an improvement of the cooling performance by approximately 10%.

Comparative effectiveness of a mnemonic-use approach vs. self-study to interpret a lateral chest X-ray

The chest X-ray is the most commonly performed medical imaging study; however, the lateral chest film intimidates many physicians and medical students. The lateral view is more difficult to interpret than the frontal view but provides important information that is either not visible or not as evident on frontal view, and inability to read it may lead to missed diagnoses and more expensive imaging. The objective of this study was to assess a novel mnemonic-based approach to teaching medical students to proficiently read a lateral film using a prospective pilot study. A clinical faculty radiologist taught two groups of second-year medical students to read a lateral chest X-ray. One group learned a novel mnemonic-based method (MUM), and the other cohort performed directed web-based self-study (STMM). Each cohort was given a pre- and postassessment, and their performance was analyzed. A total of n = 29 students participated with n = 14 being taught the mnemonic method. The MUM group significantly ( P = 0.001) improved their score vs. the STMM group This study demonstrates students can quickly and effectively learn to read a lateral chest film using this novel mnemonic.

Ropy foam-like TiO2 film grown by water-based process for electron-conduction layer of perovskite solar cells

ABSTRACTSelf-assembled TiO2 foam-like films, were grown by the water based Streaming Process for Electrodeless Electrochemical Deposition (SPEED). The morphology of the ∼1 µm thick films consists of a tangled ropy structure with individual strands of ∼200 nm diameter and open pores of 0.1 to 3 micron dimensions. Such films are advantageous for proposed perovskite solar cell comprising CH3NH3PbI3 absorber with additional inorganic films as contact and conduction layers, all deposited by SPEED. Lateral film resistivity is in the range 20 – 200 kΩ-cm, increasing with growth temperature, while sheet resistance is in the range 2 – 20 x 108 Ω/Sq. X-ray diffraction confirms presence of TiO2 crystals of orthorhombic class (Brookite). UV-vis spectroscopy shows high transmission below the expected 3.2 eV TiO2 bandgap. Transmittance increases with growth temperature.

Parametric Study on Anti-Vortex Film Cooling Hole Arrangements

Film cooling has been extensively used to provide thermal protection for the external surface of the gas turbine blades. Numerous number of film cooling holes designs and arrangements have been introduced. The main motivation of these designs and arrangements are to reduce the lift-off effect cause by the counter rotating vortices (CRVP) produce by cylindrical cooling hole. One of the efforts is the introduction of newly found anti-vortex film cooling design. The present study focuses on anti-vortex holes arrangement consists of a main hole and pair of smaller holes. All three holes share a common inlet with the outlet of the smaller holes varies base on it relative position towards the main hole. Three anti-vortex holes arrangements have been considered; downstream anti-vortex hole arrangement (DAV), lateral anti-vortex hole arrangement (LAV), and upstream anti-vortex hole arrangement (UAV). In addition, a single hole (SH) film cooling has also been considered as the baseline. The investigation make used of ANSYS CFX software ver. 14. The investigations are made through Reynolds Average Navier Stokes analyses with the application of shear k-ε turbulence model. The results show that the anti-vortex designs produce significant improvement in term of film cooling effectiveness and distribution. The LAV arrangement shows the best film cooling effectiveness distribution among all considered cases and is consistent for all blowing ratios (BR). The results also unveil the formation of new vortex pair on both side of the primary hole CRVP. Interaction between the new vortices and the main CRVP structure reduce the lift off explaining the increased lateral film effectiveness.