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A modulated force thermomechanical analysis (mf-TMA) and thermodilatometric analysis (TDA) of the green ceramic mixture of kaolin (27 wt.%), Al2O3 (50 wt.%) and feldspar (23 wt.%) up to 1000 °C is presented. The mf-TMA reflects changes during heating the green ceramics with higher sensitivity than TDA. Discrepancies between mf-TMA and TDA revealed that the elastic behavior of the green porcelain samples is determined most importantly by processes on the crystal boundaries (escaping of the water molecules at the low temperatures up to 150 °C and solid state sintering at the temperatures above 450 °C). Processes in the crystal interiors (e.g. dehydroxylation) have a lesser function. Thermodilatometric results depend more on the processes which take place inside the crystals than on the processes on the crystal surfaces. 相似文献
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Anton A. Kovalchuk Vitaliy G. Shevchenko Alexander N. Shchegolikhin Polina M. Nedorezova Alla N. Klyamkina Alexander M. Aladyshev 《Journal of Materials Science》2008,43(22):7132-7140
Isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP) nanocomposites containing 0.1–3.5 wt.% multi-wall carbon
nanotubes (MWCNTs) have been synthesized via in situ polymerization method with the use of C2- and Cs- symmetry zirconocenes activated by methylaluminoxane (MAO) in liquid propylene medium. Fracture morphology studies by SEM
reveal different MWCNT dispersion efficiency in various polymer matrices, which arises from the catalytic peculiarities of
the composite synthesis. Considerable Young’s modulus enhancement of iPP and sPP (25–66%) takes place even at low MWCNT loadings
(below 0.5 wt.%). The obtained nanocomposites can find use as efficient electromagnetic shielding materials and microwave
absorbing filters due to relatively low permittivity values and considerable dielectric losses in microwave range. Calorimetry
data demonstrate that MWCNTs exert evident influence as nucleating agents causing the rise of iPP and sPP crystallization
temperature. Considerable retardation effect on iPP thermal oxidative degradation has been observed: the temperature of maximal
weight loss rate rises by ~52 °C upon incorporating only 1.4 wt.% MWCNTs. 相似文献
127.
The supercritical carbon dioxide (S-CO2) Brayton cycle is a promising advanced alternative to the Rankine steam cycle and recuperated gas Brayton cycle for the energy converters of specific reactor concepts belonging to the U.S. Department of Energy Generation IV Nuclear Energy Systems Initiative. A new plant dynamics analysis computer code has been developed for simulation of the S-CO2 Brayton cycle coupled to an autonomous, natural circulation lead-cooled fast reactor (LFR). The plant dynamics code was used to simulate the whole-plant response to accident conditions. The specific design features of the reactor concept influencing passive safety are discussed and accident scenarios are identified for analysis. Results of calculations of the whole-plant response to loss-of-heat sink, loss-of-load, and pipe break accidents are demonstrated. The passive safety performance of the reactor concept is confirmed by the results of the plant dynamics code calculations for the selected accident scenarios. 相似文献
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Anton E 《Reproduction (Cambridge, England)》2003,125(6):879-887
The apoptotic process evoked by efferent duct ligation in the testes of adult rats was followed for 10 days by differential staining for haematoxylin-eosin, periodic acid-Schiff and a modified trichrome technique in optical microscopy and by ultrastructural localization of acid phosphatase. Round spermatids showed the first effects of efferent duct ligation. At day 3 after ligation, annular clumps of chromatin with typical apoptotic characteristics appeared against the nuclear membrane of these cells. Afterwards, membranous structures and a wide separation between the two layers of the nuclear membrane were observed but nuclear fragmentation did not occur and apoptotic granules were not seen. Cytoplasmic components were also altered, and severely damaged organoids and empty vacuoles lacking acid phosphatase reaction were frequently seen. On day 2 after efferent duct ligation, multinucleated giant cells appeared, which displayed similar characteristics as spermatids and showed no acid phosphatase reaction. Although abnormal spermatids and multinucleated giant cells were surrounded by the cytoplasm of Sertoli cells, neither lysosomal acid phosphatase nor phagocytic activity was detected. It is concluded that efferent duct ligation specifically affects round immature spermatids eliciting a partial nuclear apoptotic response that is not accompanied by autophagic or heterophagic activity and without lysosomal participation in Sertoli cells. 相似文献
130.
Peth C Kalinin A Barkusky F Mann K Toennies JP Rusin LY 《The Review of scientific instruments》2007,78(10):103509
We present a laser driven soft x-ray source based on a novel solid argon filament. The continuously flowing micron-sized filament (diameter approximately 56 microm, flow speed approximately 5 mms) was used as a laser target in order to generate a plasma source of high brightness in the "water window" (2.2-4.4 nm) spectral range. The emission properties of the source were characterized in detail with respect to crucial parameters such as positional and energy stability using an extreme ultraviolet (XUV) sensitive pinhole camera and an XUV spectrometer. The results are compared with an argon plasma based on a gas puff target operated under the same experimental conditions showing an increase of the brilliance by a factor of 84. By changing the capillary geometry from a constant diameter to a convergent shape the flow speed of the filament was significantly increased up to 250 mms, facilitating the operation at higher repetition rates. 相似文献