A Wind Tunnel Experimental Study of Icing on NACA0012 Aircraft Airfoil with Silicon Compounds Modified Polyurethane Coatings

Ice formation on the aerodynamic surfaces of an aircraft is regarded as a major problem in the aerospace industry. Ice accumulation may damage parts, sensors and controllers and alter the aerodynamics of the airplane, leading to a range of undesired consequences, including flight delays, emergency landings, damaged parts and increased energy consumption. There are various approaches to reducing ice accretion, one of them being the application of icephobic coatings. In this work, commercially available polyurethane-based coatings were modified and deposited on NACA 0012 aircraft airfoils. A hybrid modification of polyurethane (PUR) topcoats was adopted by the addition of nanosilica and three-functional spherosilicates (a variety of silsesqioxane compound), which owe their unique properties to the presence of three different groups. The ice accretion on the manufactured nanocomposites was determined in an icing wind tunnel. The tests were performed under three different icing conditions: glaze ice, rime ice and mixed ice. Furthermore, the surface topography and wetting behavior (static contact angle and contact angle hysteresis) were investigated. It was found that the anti-icing properties of polyurethane nanocomposite coatings strongly depend on the icing conditions under which they are tested. Moreover, the addition of nanosilica and spherosilicates enabled the reduction of accreted ice by 65% in comparison to the neat topcoat.     

Lung transplantation from donors outside standard acceptability criteria – are they really marginal?

Lung transplantation (LTx) from “extended donor criteria” donors may reduce significantly organ shortage. However, its influence on results remains unclear. In this study, we evaluate retrospectively the results of LTx from donors outside standard criteria: PaO2/FiO2 ratio < 300 mmHg, age over 55 years, and history of smoking > 20 pack‐years. Two hundred and forty‐eight patients underwent first time LTx in our institution between January 2007 and January 2013. Seventy‐nine patients (Group I) received organs from “extended donor criteria” and 169 patients (Group II) from “standard donor criteria.” Recipients' and donors' demographics, perioperative variables, and outcome were compared. Donors from Group I were significantly older [median (interquartile range)]: 52.5 (44;58) vs. 42 (28.5;48.5) years (P < 0.001) with lower PaO2/FiO2 ratio: 366 ± 116.1 455 ± 80.5 mmHg (P < 0.001), higher incidence of smoking history: 57.7% vs. 41.8% (P = 0.013), and more extensive smoking history: 24(15;30) vs. 10(3.75;14) pack‐years (P < 0.001). Other parameters were comparable. Recipients' gender, diagnosis, percentage of patients operated on pump and receiving double LTx were also comparable. Recipients from Group I were significantly older: 50 (42;57) vs. 44 (29.5;53.5) years (P = 001). There were no differences observed in recipients' prevalence of primary graft dysfunction (PGD) grade 3 over first three postoperative days, duration of mechanical ventilation, intensive care and hospital length of stay, prevalence of rejection, and bronchiolitis obliterans syndrome (BOS). 90‐day, 1‐year, and 5‐year survival (Group I vs. II) were also similar: 88.6% vs. 91.7%, 83.2% vs. 84.6%, and 59% vs. 68.2% (log rank P = 0.367). Carefully selected donor lungs from outside the standard acceptability criteria may expand existing donor pool with no detrimental effect on LTx outcome.     

Thermochemical and spectroscopic studies on the supramolecular complex of PAMAM-NH₂ G4 dendrimer and 5-fluorouracil in aqueous solution

The equilibrium of the formation of polyamidoamine dendrimer (PAMAM-NH(2) G4) and an oncological drug, 5-fluorouracil (FU) in water at room temperature has been examined. Using calorimetric titration, the number of active sites in the dendrimer combining the drug molecules and the equilibrium constant of the dendrimer-drug complex were estimated. The addition of the drug to the dendrimer active sites is an exothermic process. This process is accompanied by a beneficial change in entropy. The number of drug molecules combined by the polymer was confirmed by means of (1)H NMR spectroscopy. (1)HNMR measurements show that the dendrimer macromolecule binds the drug molecules with superficial protonated or unprotonated amine groups.     

Effect of Strain on Heating Characteristics of Silicone/CNT Composites

In this work, silicone/carbon nanotube (CNT) composites were produced using a spread coating process, followed by morphological investigations and determination of their electrical properties and heating behaviour through the application of electric potential. Composites containing varying amounts of CNT (1–7%) were investigated for their thermal behaviour with the use of an IR camera. Subsequently, thermal behaviour and electrical properties were measured when the samples were stretched (up to 20%). With the 7% CNT composites, which had a conductivity of 106 S/m, it was possible to achieve a temperature of 155 °C at a relatively low voltage of 23 V. For high CNT contents, when the potential was controlled in such a way as to maintain the temperature well below 100 °C, the temperature remained almost constant at all levels of strain investigated. At higher potentials yielding temperatures around 100 °C and above, stretching had a drastic effect on temperature. These results are critical for designing composites for dynamic applications requiring a material whose properties remain stable under strain.     

Gadolinium-enhanced pulmonary magnetic resonance angiography in the diagnosis of acute pulmonary embolism: a prospective study on 48 patients

OBJECTIVE: Gadolinium-enhanced pulmonary magnetic resonance angiography (MRA) can be an option in patients with a history of previous adverse reaction to iodinated contrast material and renal insufficiency. Radiation is also avoided. The aim of this study is to prospectively compare the diagnostic value of MRA with that of a diagnostic strategy, taking into account catheter angiography, computed tomography angiography (CTA), and lung scintigraphy [ventilation-perfusion (VQ)]. MATERIAL AND METHODS: Magnetic resonance angiography was done in 48 patients with clinically suspected pulmonary embolism (PE) using fast gradient echo coronal acquisition with gadolinium. Interpretation was done with native coronal images and multiplanar maximum intensity projection reconstructions. Results were compared to catheter angiography (n=15), CTA (n=34), VQ (n=45), as well as 6-12 months clinical follow-ups, according to a sequenced reference tree. RESULTS: The final diagnosis of PE was retained in 11 patients (23%). There were two false negatives and no false positive results with MRA. Computed tomography angiography resulted in no false negatives or false positives. Magnetic resonance angiography had a sensitivity of 82% and a specificity of 100%. CONCLUSION: In our study, pulmonary MRA had a sensitivity of 82% and a specificity of 100% for the diagnosis of PE, with slightly less sensitivity than CTA. In the diagnostic algorithm of PE, pulmonary MRA should be considered as an alternative to CTA when iodine contrast injection or radiation is a significant matter.