The article presents an analysis of the change in air voids in asphalt mixtures subjected to fatigue tests at three temperatures of 0°C, 10°C and 25°C. The X-ray computerized tomography imaging method, XCT, was used to identify the air voids in the samples. The research allowed to determine changes in the content of air voids in subsequent fatigue cycles in the sample area. The relationship between air voids volume and the stiffness modulus value was also determined during fatigue for three temperatures. The largest changes were found in samples with notches at 0°C. The analysis of the change in the content of air voids showed that the micro-cracking nucleation processes develop with the number of fatigue cycles. Using the numerical model finite element method we determined the distribution and change in fatigue damage in the extreme areas of the sample during various stages of fatigue. We found clear relationship between the damage and the increased content of air voids.
The bonding state of the asphalt layers in a road pavement structure significantly affects its fatigue life. These bondings, therefore, require detailed tests and optimization. In this paper, the analyses of the correlation between the results of laboratory static tests and the results of fatigue tests of asphalt mixture interlayer bondings were performed. The existence of the relationships between selected parameters was confirmed. In the future, the results of these analyses may allow for assessment of interlayer bondings' fatigue life based on the results of quick and relatively easy static tests.
Pancreatic ductal adenocarcinoma (PDAC) is characterized by very poor prognosis. It is caused by asymptomatic course of the disease at early stage. Symptomatic PDAC means usually advanced stage of the disease, making radical treatment impossible. Finding of biological PDAC marker could improve PDAC treatment through early diagnosis. In our study, we investigated two adipokines: omentin and chemerin concentration in PDAC, chronic pancreatitis (CP) and healthy individuals. We examined 27 PDAC patients, 10 CP patients and 36 controls. To determine concentration of adipokines we used ELISA immunoenzymatic assay. Level of both adipokines was increased when comparing control group to PDAC patients. Additionally, chemerin concentration in CP group was elevated comparing to control. To evaluate both adipokines as potential PDAC biomarkers we performed ROC analysis. Chemerin (AUC = 0.913) displayed better discriminant ability than omentin-1 (AUC = 0.73). Some authors believe that chemerin may promote tumour growth by stimulating angiogenesis and is supposed to be a factor recruiting mesenchymal stroma cells (MSC) in tumour regions. Omentin-1 can inhibit tumourigenesis by TP53 stimulation. On the other hand, according to some studies, omentin-1 may promote cancer proliferation via Akt signalling pathway. Results from our study showed signifi cantly elevated level of chemerin and omentin-1 in PDAC patients. Th erefore, w e believe that both investigated adipokines may provide promising and novel pharmacological insights for oncological diagnosis in the near future.