Computational fluid dynamicaccuracy in mimicking changes in blood hemodynamics in patients with acute type IIIb aortic dissection treated with TEVAR

Background: We aimed to verify the accuracy of the Computational Fluid Dynamics (CFD) algorithm for blood flow reconstruction for type IIIb aortic dissection (TBAD) before and after thoracic endovascular aortic repair (TEVAR). Methods: We made 3D models of the aorta and its branches using pre- and post-operative CT data from five patients treated for TBAD. The CFD technique was used to quantify the displacement forces acting on the aortic wall in the areas of endograft, mass flow rate/velocity and wall shear stress (WSS). Calculated results were verified with ultrasonography (USG-Doppler) data. Results: CFD results indicated that the TEVAR procedure caused a 7-fold improvement in overall blood flow through the aorta (p = 0.0001), which is in line with USG-Doppler data. A comparison of CFD results and USG-Doppler data indicated no significant change in blood flow through the analysed arteries. CFD also showed a significant increase in flow rate for thoracic trunk and renal arteries, which was in accordance with USG-Doppler data (accuracy 90% and 99.9%). Moreover, we observed a significant decrease in WSS values within the whole aorta after TEVAR compared to pre-TEVAR (1.34 ± 0.20 Pa vs. 3.80 ± 0.59 Pa, respectively, p = 0.0001). This decrease was shown by a significant reduction in WSS and WSS contours in the thoracic aorta (from 3.10 ± 0.27 Pa to 1.34 ± 0.11Pa, p = 0.043) and renal arteries (from 4.40 ± 0.25 Pa to 1.50 ± 0.22 Pa p = 0.043). Conclusions: Post-operative remodelling of the aorta after TEVAR for TBAD improved hemodynamic patterns reflected by flow, velocity and WSS with an accuracy of 99%

Analysis of the effectiveness of decontamination fluids on the level of biological contamination of firefighter suits

The scope of tasks of chemical and ecological rescue procedures includes prevention of terrorist attacks with biological weapons. After each action, firefighters are obliged to clean and disinfect their outfits to prevent the potential spreading of harmful microorganisms. This study aimed to analyze the effectiveness of decontamination fluids used to disinfect firefighter’s suits. Two types of clothes were analyzed: special combat clothing (NOMEX), and the heavy gas-tight chemical type 1a suit. Swabbed places were cut out and sterilized mechanically using detergent and alcohol. Each time, smears were made on sterile glass, fixed in pure ethanol and stained using the Gram method. After this, the staining samples were air dried and photographed under a light microscope at magnification 1000×. Each smear was made in triplicate and the relative number of stained microorganisms was analyzed using ImageJ software. The results showed that detergent significantly decreased the number of pathogens in the chest area on the NOMEX suit and the type 1a-gas-tight clothing and was more effective than alcohol, especially in case of the NOMEX suit. In conclusion, the detergent was more efficient in decontaminating the NOMEX outfit than the heavy gas-tight clothing, whose surface was better cleaned by the alcohol

Numerical description of jet and duct ventilation in underground garage after LPG dispersion

Contamination of toxic and odorous gases emitted from stacks in buildings located in an urban environment are potential health hazards to citizens. A simulation using the computational fluid dynamic technique may provide detailed data on the flammable region and spatial dispersion of released gases. Concentrations or emissions associated with garage sources and garage-to-house migration rates are needed to estimate potential exposures and risk levels. Therefore, the aim of the study was to use an original mathematical model to predict the most accurate locations for LPG sensors in an underground garage for vehicles powered with LPG. First, the three-dimensional geometry of an underground garage under a multi-family building was reconstructed. Next, two types of ventilation, jet and duct, were considered, and different sources of LPG leakage were assumed. Then, the Ansys Fluent software was applied as a solver, and the same initial value of released LPG (5 kg) was assumed. As a simplification, and to avoid the simulation of choked outflow, the emission from a large area was adopted. The results showed stagnation areas for duct ventilation in which gas remained for both the jet and duct ventilation. Moreover, it was observed that the analyzed gas would gather in the depressions of the ground in the underground garage, for example in drain grates, which may create a hazardous zone for the users of the facility. Additionally, it was observed that for jet ventilation, turbulence appearance sometimes generated differentiated gas in an undesirable direction. The simulation also showed that for blowing ventilation around the garage, and for higher LPG leakage, a higher cloud of gas that increased probability of ignition and LPG explosion was formed. Meanwhile, for jet ventilation, a very low concentration of LPG in the garage was noticed. After 35 s, LPG concentration was lower than the upper explosive limit. Therefore, during the LPG leakage in an underground garage, jet ventilation was more efficient in decreasing LPG gas to the non-explosive values

Analiza procesu sorpcji dla płynu hamulcowego i oleju napędowego po zastosowaniu sorbentu compakt

During car accidents the leakage of petroleum substances together with the vehicle fluids appear. One of the basic duties of the Fire Department in the field of ecological protection is to support the area of car accident with the use of sorbates. Therefore, the aim of the study was to compare the sorption process for the different sorbates in contact with the compact sorbent. The analysis of sorption process in a laboratory scale was performed with the use of a dedicated installation. Contact of two sorbates with the compact sorbent was investigated. Each time 50 cm3 of the sorbent was contacted with 100 cm3 of the sorbate in the following properties: 100% of brake fluid, 100% of diesel, 75% of brake fluid and 25% of diesel, 50% of brake fluid and 50% of diesel, 25% of brake fluid and 75% of diesel. Finally, the results of the mathematical description of the sorption process with a non-linear regression were prepared. It was observed that the sorption process for pure brake fluid that contacted with the compact sorbent was stopped after the absorption of 24.80±0.27 g, while, for pure diesel it was stopped after 21.09±0.35 g. The average sorption was equal to 0.83 and 0.72 for brake fluid and diesel, respectively. Furthermore, for a mixture of brake fluid (75%) – diesel (25%) the sorption process was stopped after the absorption of 18.39±0.17 g, while for a mixture of brake fluid (25%) – diesel (75%) it was stopped after 22.06± 0.54 g. The average sorption was equal to 0.63 and 0.37 for brake fluid (75%) and diesel (25%), as well as for brake fluid (25%) and diesel (75%). Finally, for the mixture of brake fluid (50%) and diesel (50%) the sorption process was stopped after the absorption of 21.85±0.49 g, with average sorption equal to 0.72. It was observed that the sorption process was longer for brake fluid compared to diesel. The decrease of brake fluid amount led to the decrease of the sorption value. Moreover, the higher amount of brake fluid was associated with the higher value of the correlation coefficients after the application of fifth degree polynomial adjustment.Podczas wypadków samochodowych pojawiają się wycieki substancji ropopochodnych, a także płynów eksploatacyjnych. Jednym z obowiązków straży pożarnej jest zabezpieczenie miejsca zdarzenia drogowego. Celem przedmiotowych badań była analiza procesu sorpcji różnych sorbatów przy pomocy sorbentu compakt. Analiza procesu sorpcji dwóch sorbatów w skali laboratoryjnej została przeprowadzona z wykorzystaniem dedykowanej aparatury eksperymentalnej. Za każdym razem kontaktowano 50 cm3 sorbentu compakt z 100 cm3 sorbatu o następującym składzie: 100% płynu hamulcowego, 100% oleju napędowego, 75% płynu hamulcowego i 25% oleju napędowego, 50% płynu hamulcowego i 50% oleju napędowego, 25% płynu hamulcowego i 75% oleju napędowego. Co więcej, wyniki eksperymentów zostały opisane przy pomocy nieliniowej regresji. Zaobserwowano, że proces sorpcji czystego płynu hamulcowego (100%) w kontakcie z sorbentem compakt zakończył się po zaabsorbowaniu 24.80±0.27 g sorbatu, podczas gdy proces sorpcji dla czystego oleju napędowego (100%) zatrzymał się po zaabsorbowaniu 21.09±0.35 g sorbatu. Średnia sorpcja wynosiła odpowiednio 0.83 i 0.72 dla płynu hamulcowego i oleju napędowego. Co więcej, dla mieszaniny płyn hamulcowy (75%) – olej napędowy (25%) proces sorpcji zatrzymał się po zaabsorbowaniu 18.39±0.17 g sorbatu. Natomiast dla mieszaniny płyn hamulcowy (25%) – olej napędowy (75%) proces sorpcji zatrzymał się po zaabsorbowaniu 22.06± 0.54 g sorbatu. Średnia sorpcja wynosiła odpowiednio 0.63 i 0.37 dla mieszaniny płyn hamulcowy (75%) i olej napędowy (25%) i płyn hamulcowy (25%) i olej napędowy (75%). Na koniec przeanalizowano procesu sorpcji dla mieszaniny płyn hamulcowy (50%) i olej napędowy (50%). Proces sorpcji zatrzymał się po zaabsorbowaniu 21.85±0.49 g sorbatu, a średnia sorpcja wynosiła 0.72. Proces sorpcji był znacznie dłuższy dla płynu hamulcowego w porównaniu do oleju napędowego. Zmniejszenie zawartości płynu hamulcowego prowadziło do zmniejszenia wartości sorpcji. Co więcej, większa zawartość płynu hamulcowego korelowała z wyższymi wartościami współczynników korelacji dla wielomianu piątego stopnia opisującego wyniki eksperymentu

The influence of soil and liquid temperature on the process of permeability of selected operating fluids used in motor vehicles

Substancje ropopochodne ze względu na właściwości fizykochemiczne blokują pory gleby, powodując powstanie warstwy nieprzepuszczalnej, m.in. dla wody lub powietrza. Gleby o strukturze luźniejszej wykazują niższą odporność na działanie degradującej substancji ropopochodnej. Celem pracy było określenie wpływu temperatury gleby oraz temperatury wybranych płynów eksploatacyjnych na stopień przesiąkania gleby. W pracy analizowano płyny eksploatacyjne stosowane w pojazdach silnikowych, z którymi jednostki ochrony przeciwpożarowej mają najczęściej do czynienia podczas interwencji w zdarzeniach drogowych. Badaniu poddano płyn chłodniczy oraz olej silnikowy. Badanie przesiąkania cieczy przez piasek wykonano w warunkach laboratoryjnych, analizując każdorazowo 150 cm3 piasku, do którego wprowadzano dwukrotnie 100 ml badanej cieczy, co umożliwiło określenie przepuszczalności gleby w funkcji stopnia jej wilgotności. Ciecze były analizowane w trzech temperaturach: 7°C, 23°C i 85°C, natomiast piasek w dwóch temperaturach: 10°C i 25°C. Na podstawie przeprowadzonych badań zaobserwowano, iż czas przesiąkania cieczy przez grunt maleje wraz ze wzrostem temperatury cieczy. Co więcej, wraz ze wzrostem temperatury gruntu czas przesiąkania cieczy przez grunt ulega skróceniu. Jest to związane ze spadkiem lepkości cieczy oraz wzrostem współczynnika filtracji.Petroleum substances block the pores of the soil causing an impermeable layer, e.g. for water or air. Soils with a looser structure show lower resistance to the degrading oil-derivative substance. The purpose of the work was to determine the effect of soil temperature and temperature of selected exploitation fluids on the degree of soil permeability. Permeability of the liquid through the sand was carried out in the laboratory conditions. Each time to 150 cm3 of sand two volumes of 100 cm3 tested liquid were added. Cooling fluid and engine oil were tested. The liquids were analyzed at three temperatures: 7°C, 23°C and 8°C, and sand was analyzed at two temperatures: 10°C and 25°C. On the basis of the conducted tests, it was observed that the time of liquid permeability through the soil decreased with the increasing temperature of the liquid. Moreover, as the soil temperature raised, the time the liquid seeped through the ground was reduced. This was related to the decrease in viscosity of the liquid and the increase in the filtration coefficient