Magnetotransport study on AllnN/(GaN)/AIN/GaN heterostructures

Cataloged from PDF version of article.We report the effect of a thin GaN (2?nm) interlayer on the magnetotransport properties of AlInN/AlN/GaN-based heterostructures. Two samples were prepared (Sample A: AlInN/AlN/GaN and sample B: AlInN/GaN/AlN/GaN). Van der Pauw and Hall measurements were performed in the 1.9300?K temperature range. While the Hall mobilities were similar at room temperature (RT), sample B had nearly twice as large Hall mobility as sample A at the lowest temperature; 679 and 889?cm2/Vs at RT and 1460 and 3082?cm2/Vs at 1.9?K for samples A and B. At 1.910?K, the longitudinal magnetoresistance was measured up to 9?T, in turn revealing Shubnikovde Haas (SdH) oscillations. The carrier concentration, effective mass and quantum mobility of the two-dimensional electron gas (2DEG) were determined from SdH oscillations. At 1.9?K, the 2DEG concentration of sample B was nearly seven times larger than of sample A (1.67 x 10(13)/cm2 vs. 0.24 x 10(13)/cm2). On the contrary, the quantum mobility was changed adversely nearly three times (sample B 2500?cm2/Vs and sample A 970?cm2/Vs). The increase of the 2DEG concentration was attributed to the existence of the GaN interlayer, which has strengthened the spontaneous polarization difference between the AlInN and GaN layers of the heterostructure. Hence, the stronger electric field at the 2DEG region bent the conduction band profile downwards and consequently the quantum mobility decreased due to the increased interface roughness scattering

A rare case of sarcoidosis involving the middle turbinates: an incidental diagnosis

BACKGROUND: Sarcoidosis is a chronic, systemic granulomatous disease of unknown etiology that features noncaseating granulomas in many body regions. Sinonasal involvement is rare but is also suspected to be underreported. CASE PRESENTATION: We present the case of a 39-year-old woman who was incidentally diagnosed with isolated sarcoidosis involving the middle turbinates. Histopathologic examination of resected concha bullosa material and an extensive panel of diagnostic tests revealed a diagnosis of isolated sarcoidosis. Since no systemic manifestations were detected, topical corticosteroid (nasal spray) was administered in the postoperative period. Throughout the 12 months after surgery, the patient remained free of symptoms and all nasal endoscopy examinations were normal. CONCLUSION: Although isolated nasal involvement of sarcoidosis is rare, otorhinolaryngologists should consider this condition in a differential diagnosis for sinonasal complaints

The effectiveness of exercise programmes after lumbar disc surgery: a randomized controlled study

Objective: To compare two different exercise programmes versus a control group, after lumbar disc surgery

Effects of Methyl Acetate as Oxygenated Fuel Blending on Performance and Emissions of SI Engine

The objective of this paper is to investigate the use of methyl acetate as oxygenated fuel blending for base gasoline in SI engine. The effects of methyl acetate on engine performance parameters (brake specific fuel consumption, brake thermal efficiency and energy consumption rate) and exhaust emissions (CO, HC, CO2 and NOx) of SI engine have been experimentally investigated. Engine experiments were conducted on a single cylinder, water cooled, spark-ignition test engine at constant moderate speed; 1500 rpm for different loads; 104, 207, 311 and 414 kPa fuelling the engine with base gasoline, M5 (95 % base gasoline +5 % methyl acetate) and M10 (90 % base gasoline +10 % methyl acetate). The results showed that adding methyl acetate to base gasoline increases the brake specific fuel consumption while reducing the brake thermal efficiency of the engine. Furthermore, it was also observed that methyl acetate addition does not have a great effect on HC emissions, however, reduces CO and increases CO2 emissions. NOx results showed a striking increase in the level of NOx emissions with the addition of methyl acetate

Oxidative status and paraoxonase activity in children with asthma

Objective: To compare paraoxonase activity and changes in oxidative status in asthmatic children and healthy children by determining serum paraoxonase activity and total oxidative status, total antioxidant capacity and lipid hydroperoxidation. Methods: Forty two asthmatic children were compared with 32 healthy children of similar age and sex. To evaluate the paraoxonase and oxidative status, total antioxidant capacity and lipid hydroperoxidation were examined. Serum paraoxonase activity was evaluated by measuring the rate of paraoxon hydrolosis. Oxidative status was evaluated by the method developed by Erel. Lipid hydroperoxide was measured by an iodometric method. Results: In comparison with the healthy control group, the paraoxonase activity of the asthmatic children was found to be low (163.7 ± 73.0 (U/L) and 349.2 ± 153.9 (U/L), P = 0.002) and total oxidant status (9.0 ± 3.5 ?mol H2O2 Eq/L and 13.4 ± 7.0 ?mol H2O2 Eq/L, P =0.002), total antioxidant capacity (5.5 ± 2.5 µmol Trolox Eq/L and 1.0 ± 0.6 µmol Trolox Eq/L, P < 0.001), and lipid hydroperoxidation values (9.9 ± 3.4 ?mol H2O2 Eq/L and 4.4 ± 1.5 ?mol H2O2 Eq/L, P < 0.001) were found to be high. The high density lipoprotein (HDL) concentration of the asthmatic children was lower than that in the control group (40.1 ± 9.2 mg/dl and 54.5 ± 15.9 mg/dl, P < 0.001) Conclusion: In asthmatic children, when total oxidant status, total antioxidant capacity and lipid hydroperoxidation levels increase, paraoxonase activity decreased