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排序方式: 共有221条查询结果,搜索用时 15 毫秒
1.
Akylbek Sydykov Himal Luitel Argen Mamazhakypov Malgorzata Wygrecka Kabita Pradhan Oleg Pak Aleksandar Petrovic Baktybek Kojonazarov Norbert Weissmann Werner Seeger Friedrich Grimminger Hossein Ardeschir Ghofrani Djuro Kosanovic Ralph Theo Schermuly 《International journal of molecular sciences》2020,21(23)
Although the response of the right ventricle (RV) to the increased afterload is an important determinant of the patient outcome, very little is known about the underlying mechanisms. Mast cells have been implicated in the pathogenesis of left ventricular maladaptive remodeling and failure. However, the role of mast cells in RV remodeling remains unexplored. We subjected mast cell-deficient WBB6F1-KitW/W-v (KitW/KitW-v) mice and their mast cell-sufficient littermate controls (MC+/+) to pulmonary artery banding (PAB). PAB led to RV dilatation, extensive myocardial fibrosis, and RV dysfunction in MC+/+ mice. In PAB KitW/KitW-v mice, RV remodeling was characterized by minimal RV chamber dilatation and preserved RV function. We further administered to C57Bl/6J mice either placebo or cromolyn treatment starting from day 1 or 7 days after PAB surgery to test whether mast cells stabilizing drugs can prevent or reverse maladaptive RV remodeling. Both preventive and therapeutic cromolyn applications significantly attenuated RV dilatation and improved RV function. Our study establishes a previously undescribed role of mast cells in pressure overload-induced adverse RV remodeling. Mast cells may thus represent an interesting target for the development of a new therapeutic approach directed specifically at the heart. 相似文献
2.
Balakshin Yu. V. Kozhemiako A. V. Petrovic S. Erich M. Shemukhin A. A. Chernysh V. S. 《Semiconductors》2019,53(8):1011-1017
Semiconductors - Experimental depth distributions of the concentration of implanted xenon ions depending on their charge state and irradiation energy are presented. Xenon ions in charge states q =... 相似文献
3.
Ivana M. Radovic Dusica B. Stojanovic Aleksandar Kojovic Milos Petrovic Petar S. Uskokovic Vesna J. Radojevic 《Polymer-Plastics Technology and Engineering》2017,56(11):1188-1195
The study presents a novel method for protection of the first- and the second-generation Grubbs’ catalyst, by incorporation in poly(styrene) fibers through electrospinning technique. Both catalysts are sensitive to the presence of the amine hardeners in the epoxy-based self-healing composites and require protection from deactivation to retain their ability to promote polymerization reaction of the healing agent. Comparison of healing efficiencies of both catalysts suggested that poly(styrene) fibers offer better protection and dispersion for the first-generation Grubbs’ catalyst, although all the samples exhibited high-healing efficiency. Difference in stereoselectivity between two catalysts was also indicated. 相似文献
4.
Uranium-zirconium hydride fuel properties 总被引:1,自引:0,他引:1
Properties of the two-phase hydride U0.3ZrH1.6 pertinent to performance as a nuclear fuel for LWRs are reviewed. Much of the available data come from the Space Nuclear Auxiliary Power (SNAP) program of 4 decades ago and from the more restricted data base prepared for the TRIGA research reactors some 3 decades back. Transport, mechanical, thermal and chemical properties are summarized. A principal difference between oxide and hydride fuels is the high thermal conductivity of the latter. This feature greatly decreases the temperature drop over the fuel during operation, thereby reducing the release of fission gases to the fraction due only to recoil. However, very unusual early swelling due to void formation around the uranium particles has been observed in hydride fuels. Avoidance of this source of swelling limits the maximum fuel temperature to ∼650 °C (the design limit recommended by the fuel developer is 750 °C). To satisfy this temperature limitation, the fuel-cladding gap needs to be bonded with a liquid metal instead of helium. Because the former has a thermal conductivity ∼100 times larger than the latter, there is no restriction on gap thickness as there is in helium-bonded fuel rods. This opens the possibility of initial gap sizes large enough to significantly delay the onset of pellet-cladding mechanical interaction (PCMI). The large fission-product swelling rate of hydride fuel (3× that of oxide fuel) requires an initial radial fuel-cladding gap of ∼300 m if PCMI is to be avoided. The liquid-metal bond permits operation of the fuel at current LWR linear-heat-generation rates without exceeding any design constraint. The behavior of hydrogen in the fuel is the source of phenomena during operation that are absent in oxide fuels. Because of the large heat of transport (thermal diffusivity) of H in ZrHx, redistribution of hydrogen in the temperature gradient in the fuel pellet changes the initial H/Zr ratio of 1.6 to ∼1.45 at the center and ∼1.70 at the periphery. Because the density of the hydride decreases with increasing H/Zr ratio, the result of H redistribution is to subject the interior of the pellet to a tensile stress while the outside of the pellet is placed in compression. The resulting stress at the pellet periphery is sufficient to overcome the tensile stress due to thermal expansion in the temperature gradient and to prevent radial cracking that is a characteristic of oxide fuel. Several mechanisms for reduction of the H/Zr ratio during irradiation are identified. The first is transfer of impurity oxygen in the fuel from Zr to rare-earth oxide fission products. The second is the formation of metal hydrides by these same fission products. The third is by loss to the plenum as H2.The review of the fabrication method for the hydride fuel suggests that its production, even on a large scale, may be significantly higher than the cost of oxide fuel fabrication. 相似文献
5.
P. B. Petrovic 《Measurement Techniques》2011,53(11):1264-1271
The estimation of the truncation error in the asynchronous sampling of an ac signal containing sub- and interharmonic components
is considered. The expressions derived enable one to choose the optimum method and the necessary number of samples of a complex
input signal. The limits of the error of the method of signal processing are determined taking the effect of sampling into
account. Mathematical modeling of the procedure for estimating the possible truncation error is carried out. 相似文献
6.
Leena Maunula Agnieszka Kaupke Petra Vasickova Kirsi Söderberg Iwona Kozyra Sava Lazic Wim H.M. van der Poel Martijn Bouwknegt Saskia Rutjes Kris A. Willems Rita Moloney Martin D'Agostino Ana Maria de Roda Husman Carl-Henrik von Bonsdorff Artur Rzeżutka Ivo Pavlik Tamas Petrovic Nigel Cook 《International journal of food microbiology》2013
In recent years, numerous foodborne outbreaks due to consumption of berry fruit contaminated by human enteric viruses have been reported. This European multinational study investigated possible contamination routes by monitoring the entire food chain for a panel of human and animal enteric viruses. 相似文献
7.
C. Shuffler P. Diller E. Greenspan B. Petrovic 《Nuclear Engineering and Design》2009,239(8):1505-1530
An economic analysis is performed to calculate the levelized unit cost of electricity (COE) for a pressurized water reactor (PWR) retrofitted with a range of potential U (45 wt.%)-ZrH1.6 hydride and UO2 oxide fueled geometries (i.e., combinations of rod diameter and pitch) supported by traditional grid spacers (square array) and wire wrap spacers (hexagonal array). The time frame considered in computing the COE is the remaining plant life, beginning at the time of retrofit. The goals of the analysis are twofold: (1) comparing the economic performance of UO2 and U-ZrH1.6 fuels for a range of retrofitted geometries supported by grid and wire wrap spacers; and (2) investigating the potential economic benefits for nuclear utilities considering retrofitting new fuels and/or geometries into existing PWR pressure vessels. Fuel cycle, operations and maintenance (O & M), and capital costs are considered.The economic performance of U-ZrH1.6 and UO2 fuels is found to be similar, with UO2 fueled designs providing a slight advantage when supported by grid spacers, and U-ZrH1.6 providing a slight advantage when supported by wire wrap spacers. These small differences in cost, however, are within the bounds of uncertainty of this study and are not believed to provide a strong economic argument for the use of one fuel type over the other.To demonstrate the potential economic benefits of retrofitted designs to nuclear utilities, two different comparisons are made. The first compares the COE for retrofitted designs with the COE for a reference PWR, assumed to have operated long enough to recuperate its initial capital investment. The costs for this reference PWR reflect the “do-nothing” case for current plant owners whose primary expenditures are fuel cycle and O & M costs. The second comparison introduces a different reference PWR that includes the costs to operate an existing unit and the cost to purchase power from a newly constructed PWR, for comparison with retrofitted designs which offer increased power relative to existing commercial PWRs.For the first comparison, no grid supported designs and only one wire wrap supported design (i.e., U-ZrH1.6 Stretch Case) provide a lower levelized unit cost of electricity than the reference “do-nothing” PWR. The primary cause of this conclusion is the capital costs incurred by retrofitted designs to change the core geometry and, for many designs, to upgrade primary and secondary loop components for operation at higher power than the reference PWR. The reference “do-nothing” PWR cost in this first comparison includes only operations and maintenance as well as fuel cycle costs but does not include a capital component. For the second comparison, significant cost savings are demonstrated for both grid (15-19% savings) and wire wrap (30-40% savings) supported designs using U-ZrH1.6 and UO2 fuels. These cost savings are enabled by enhancing the pumping capacity of the primary system and, for wire wrap supported designs, by taking advantage of enhanced critical heat flux performance. The optimal geometry for retrofitted UO2 and U-ZrH1.6 fueled PWR cores supported by grid spacers is Drod = 6.5 mm and P/D = 1.39. The cost savings over the second case reference PWR are ∼19 and 15%, respectively. The cost savings for retrofitted PWRs that incorporate wire wrap spacing are even larger because of operation at even higher power. Cost savings over the reference PWR range between 30 and 40% for the U-ZrH1.6 and UO2 Achievable and Stretch Cases. The optimal geometries for the U-ZrH1.6 Achievable and Stretch Cases are Drod = 8.08 mm, P/D = 1.41 and Drod = 8.71 mm, P/D = 1.39, respectively. The optimal geometries for the UO2 Achievable and Stretch Cases are Drod = 7.13 mm, P/D = 1.42 and Drod = 9.34 mm, P/D = 1.27, respectively. Utilities seeking to meet rising demand by expanding capacity may therefore strongly benefit from retrofitting existing PWRs with either U-ZrH1.6 or UO2 fueled designs. These new designs have different geometries than are currently used by commercial plants. A conclusion on which fuel type to use, however, could not be reached in this analysis as both offer similar economic performance. 相似文献
8.
Adel A. Sharif Fuming Chu Amit Misra Terence E. Mitchell John J. Petrovic 《Journal of the American Ceramic Society》2000,83(9):2246-2250
The elastic properties of single-crystalline erbia (Er2 O3 ) at room temperature have been investigated using resonant ultrasound spectroscopy. The three independent stiffness constants of anisotropic Er2 O3 cubic type-C crystals have been measured. The values of the stiffness constants were c 11 = 256.4 GPa, c 12 = 146.8 GPa, and c 44 = 75.2 GPa. From the stiffness constants, the estimated values for dense polycrystalline erbia for Young's modulus, the shear modulus, the bulk modulus, and Poisson's ratio at room temperature were 179 GPa, 67 GPa, 183.3 GPa, and 0.337, respectively. The value of Young's modulus is a minimum along [001] and a maximum along [111]. The value of the shear modulus is independent of the direction in the (001) and (111) planes, whereas it decreases in (11¯0) from 75 GPa along [001] to 55 GPa along [110]. 相似文献
9.
Sonja Petrovic‐Lazarevic 《Construction Management & Economics》2013,31(2):93-101
In the Australian construction industry, large companies develop corporate social responsibility (CSR) in order to maintain an image of being a good corporate citizen. CSR relevant to the construction industry is defined including the following activities: moral obligation to be a good citizen; sustainability; reputation; relationship with employees and unions; relationship with suppliers and community representatives; and commitment to reporting on CSR. CSR is then examined through 85 interviews conducted with members of boards of directors, suppliers, employees, customers and community representatives of 17 large corporations. In order to be recognized as a socially responsible business, the corporations should: apply a corporate governance structure that takes into consideration working environment concerns; improve their sustainability, occupational health and safety measures, relationships with suppliers and commitment to local community protection and engagement. 相似文献
10.
Bhikhu Suthar Daniel Klempner Kurt C. Frisch Zoran Petrovic Zelimir Jelcic 《应用聚合物科学杂志》1994,53(8):1083-1090
Three series of interpenetrating polymer networks (IPNs) based on a polyurethane (castor oil + toluene diisocyanate) with polystyrene, poly(methyl methacrylate), and poly(n-butyl methacrylate) were synthesized and characterized. Dielectric relaxation studies of these IPNs were carried out from ?150 to 100°C in the 100 Hz to 100 kHz range. The effects of structural variables such as composition, type of vinyl monomer, as well as the effect of interaction of the phases on the dielectric properties were studied. A certain degree of phase mixing was observed to exist in all series as detected by the variation of the glass-transition temperatures of the IPNs. Maxwell–Wagner–Sillars polarization at the interface of the two phases was observed. © 1994 John Wiley & Sons, Inc. 相似文献