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81.
The present paper focuses on laboratory tests of fatigue strength of prototype under ballast mats (UBMs), carried out according to the procedure described in the new European standard EN 17282, which was released in October 2020. The mineral wool-based mat revealed significant differences in the values of static and dynamic characteristics, measured before and after the fatigue tests. The elastomeric mats based on recycled materials (SBR granulate and fibers) turned out to have had sufficient durability and effectiveness of protection against vibration caused by railway traffic. The values of static and dynamic bedding moduli, determined before and after the fatigue tests, were used to develop a viscoelastic rheological model of the vibration isolator with the use of fractional derivatives. Using this original model of the ballasted track system with four degrees of freedom, a significant influence of cyclic loading on the level of vibration suppression (insertion loss factor) was demonstrated. The analytical model confirmed that the mats with variations of bedding moduli exceeding 10% should not be used as resilient elements. 相似文献
82.
Artur Bobrowski Karolina Kaczmarska Maciej Sitarz Dariusz Droyski Magdalena Leniak Beata Grabowska Daniel Nowak 《Materials》2021,14(11)
The article presents the results of research aimed at examining the type of swelling material introduced into moulding or core sand to improve their knock-out properties. Tests on Slovak perlite ore (three grain sizes), Hungarian perlite ore and ground vermiculite (South Africa) were carried out. For this purpose, thermal and structural analyses (FTIR—Fourier Transform Infrared Spectroscopy), a chemical composition test (XRF-X-Ray Fluorescence), phase analysis (XRD—X-Ray Diffraction), and scanning electron microscopy (SEM—Scanning Electron Microscope) as well as final strength tests of moulding sands with the addition of perlite ore and vermiculite were carried out. The results of thermal studies were related to IR (Infrared Spectroscopy) spectra and XRD diffractograms. It has been shown that the water content in the pearlite ore is almost three times lower than in vermiculite, but the process of its removal is different. Moreover, the chemical composition of the perlite ore, in particular the alkali content and its grain size, may influence its structure. The phenomena of expansion (perlite) and peeling (vermiculite) have a positive effect on the reduction of the final sand strength and eliminate technological inconveniences (poor knocking out) that significantly limit the wide use of moulding sands with inorganic binders. 相似文献
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Gabriel Constantinescu Sergey M. Mikhalev Aleksey D. Lisenkov Daniela V. Lopes Artur R. Sarabando Marta C. Ferro Tiago F. da Silva Sergii A. Sergiienko Andrei V. Kovalevsky 《Materials》2021,14(4)
This work further explores the possibilities for designing the high-temperature electrical performance of the thermoelectric Ca3Co4O9 phase, by a composite approach involving separate metallic iron and nickel particles additions, and by employing two different sintering schemes, capable to promote the controlled interactions between the components, encouraged by our recent promising results obtained for similar cobalt additions. Iron and nickel were chosen because of their similarities with cobalt. The maximum power factor value of around 200 μWm−1K−2 at 925 K was achieved for the composite with the nominal nickel content of 3% vol., processed via the two-step sintering cycle, which provides the highest densification from this work. The effectiveness of the proposed approach was shown to be strongly dependent on the processing conditions and added amounts of metallic particles. Although the conventional one-step approach results in Fe- and Ni-containing composites with the major content of the thermoelectric Ca3Co4O9 phase, their electrical performance was found to be significantly lower than for the Co-containing analogue, due to the presence of less-conducting phases and excessive porosity. In contrast, the relatively high performance of the composite with a nominal nickel content of 3% vol. processed via a two-step approach is related to the specific microstructural features from this sample, including minimal porosity and the presence of the Ca2Co2O5 phase, which partially compensate the complete decomposition of the Ca3Co4O9 matrix. The obtained results demonstrate different pathways to tailor the phase composition of Ca3Co4O9-based materials, with a corresponding impact on the thermoelectric performance, and highlight the necessity of more controllable approaches for the phase composition tuning, including lower amounts and different morphologies of the dispersed metallic phases. 相似文献
86.
Artur Iluk 《Materials》2021,14(5)
In the paper, the thermal compensation loops on a composite, superconducting NbTi cable were investigated. This type of cable is used in the superconducting, fast ramping magnets of the SIS100 synchrotron, part of the Facility for Antiproton and Ion Research (FAIR) under construction in Darmstadt, Germany. The influence of space restrictions and electromagnetic cross-talk on the design of the thermal compensation loop was discussed. Plastic deformation of cable components during bending was analyzed by numerical simulations and experiments. A three-dimensional numerical model of the cable was prepared with individual superconducting wires in contact with a central cooling pipe. The bending of a straight cable into a compensation loop shape was simulated, followed by cyclic operation of the cable during thermal cycles. The maximum strains in the superconducting strands and cooling tube were analyzed and discussed. 相似文献
87.
Gontarewicz A Balabanov S Keller G Colombo R Graziano A Pesenti E Benten D Bokemeyer C Fiedler W Moll J Brümmendorf TH 《Blood》2008,111(8):4355-4364
The emergence of resistance to imatinib (IM) mediated by mutations in the BCR-ABL domain has become a major challenge in the treatment of chronic myeloid leukemia (CML). Here, we report on studies performed with a novel small molecule inhibitor, PHA-739358, which selectively targets Bcr-Abl and Aurora kinases A to C. PHA-739358 exhibits strong antiproliferative and proapoptotic activity against a broad panel of human BCR-ABL-positive and -negative cell lines and against murine BaF3 cells ectopically expressing wild-type (wt) or IM-resistant BCR-ABL mutants, including T315I. Pharmacologic synergism of IM and PHA-739358 was observed in leukemia cell lines with subtotal resistance to IM. Treatment with PHA-739358 significantly decreased phosphorylation of histone H3, a marker of Aurora B activity and of CrkL, a downstream target of Bcr-Abl, suggesting that PHA-739358 acts via combined inhibition of Bcr-Abl and Aurora kinases. Moreover, strong antiproliferative effects of PHA-739358 were observed in CD34(+) cells derived from untreated CML patients and from IM-resistant individuals in chronic phase or blast crisis, including those harboring the T315I mutation. Thus, PHA-739358 represents a promising new strategy for treatment of IM-resistant BCR-ABL-positive leukemias, including those harboring the T315I mutation. Clinical trials investigating this compound in IM-resistant CML have recently been initiated. 相似文献
88.
Krzysztof Szydlo M.D. Ph.D. Krystian Wita M.D. Ph.D. Maria Trusz‐Gluza M.D. Ph.D. Dagmara Urbanczyk M.D. Ph.D. Artur Filipecki M.D. Ph.D. Witold Orszulak M.D. Ph.D. Zbigniew Tabor M.D. Jolanta Krauze M.D. Ph.D. Wojciech Kwasniewski M.D. Ph.D. Jaroslaw Myszor M.D. Ph.D. Maciej Turski M.D. Jaroslaw Kolasa M.D. Jan Szczogiel M.D. 《Annals of noninvasive electrocardiology》2008,13(1):8-13
Background: The relation between postinfarction left ventricle remodeling (LVR), autonomic nervous system and repolarization process is unclear. Purpose of the study was to assess the influence of LVR on the early (QTpeak) and late (TpeakTend) repolarization periods in patients after myocardial infarction (MI) treated with primary PCI. The day‐to‐night differences of repolarization parameters and the relation between QT and heart rate variability (HRV) indices, as well left ventricle function were also assessed. Methods: The study cohort of 104 pts was examined 6 months after acute MI. HRV and QT indices (corrected to the heart rate) were obtained from the entire 24‐hour Holter recording, daytime and nighttime periods. Results: LVR was found in 33 patients (31.7%). The study groups (LVR+ vs LVR?) did not differ in age, the extent of coronary artery lesions and treatment. Left ventricle ejection fraction (LVEF) was lower (38%± 11% vs 55%± 11%, P < 0.001), both QTc (443 ± 26 ms vs 420 ± 20 ms, P < 0.001) and TpeakTendc (98 ± 11 ms vs 84 ± 12 ms, P < 0.005) were longer in LVR + patients, with no differences for QTpeakc. Trends toward lower values of time‐domain (SDRR, rMSSD) HRV parameters were found in LVR+ pts. Day‐to‐night difference was observed only for SDRR, more marked in LVR‐group. Remarkable relations between delta LVEF (6 months minus baseline), delta LVEDV and TpeakTendc were found, with no such relationships for QTpeakc. Conclusions: The patients with LVR have longer repolarization time, especially the late phase‐ TpeakTend, which represents transmural dispersion of repolarization. Its prolongation seems to be related to local attributes of myocardium and global function of the left ventricle but unrelated to the autonomic nervous influences. Remodeling with moderate LV systolic dysfunction is associated with insignificant decrease in HRV indices and preserved circadian variability. 相似文献
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In patients undergoing percutaneous coronary intervention with rotational atherectomy radial access is safer and as efficient as femoral access 下载免费PDF全文
Piotr Kübler MD PhD Wojciech Zimoch MD Michał Kosowski MD Brunon Tomasiewicz MD Artur Telichowski MD PhD Krzysztof Reczuch MD PhD 《Journal of interventional cardiology》2018,31(4):471-477