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71.
Creep of two Ni-AI alloys containing 4.8 and 7.0 wt pct Al was studied in the temperature range 873 to 1073 K and stress range
30 to 400 MPa. The former alloy represents the solid solution of aluminum in nickel, the latter a solid solution strengthened
by NI3AI particles.
As to its creep behavior the solid solution alloy belongs to the Class n of solid solu-tions,i.e. the creep controlling mechanism is the same as in pure nickel. From the analy-sis of an effective stress dependence of steady
state creep rate it follows that the mo-tion of jogged screw dislocations can be considered as the most probable creep control-ling
mechanism.
The apparent activation energy of creep in the two phase alloy increases with tempera-ture. This effect is caused by changes
in the volume fraction of second phase particles and by the onset of climb around particles at high temperatures. At lower
temperatures particles are cut by dislocation pairs. 相似文献
72.
K. Čulik H.A. Maurer Th. Ottmann K. Ruohonen A. Salomaa 《Theoretical computer science》1978,6(2):143-173
It is shown that if two PD0L forms F1 and F2 are form equivalent, i.e., generate the same family of languages, then the PD0L sequences E(F1) and E(F2) are isomorphic, provided one of the sequences contains a word of length greater than one. This result leads to a simple algorithm of deciding the form equivalence of two PD0L forms F1 and F2. Moreover, we obtain the rather surprising result that F1 and F2 are form equivalent if and only if they are sequence equivalent, i.e., generate the same family of PD0L sequences (excluding again the trivial case that F1 and F2 generate only words of length one). 相似文献
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76.
Conductivity measurements on amorphous Ge films in the frequency range 20 Hz–26 GHz are described. Above 100 MHz the frequency dependence of the conductivity at room temperature satisfied the power law σ∝ωs with s=0.45-0.7. No saturation of the conductivity was observed. When the Ge films were doped with 0.1–1 at. % Sb the conductivity was frequency independent up to 26 GHz. A.c. hopping conduction seems to be compatible with the experimental results. 相似文献
77.
78.
Leona Buňková František Buňka Gabriela Mantlová Andrea Čablová Ivo Sedláček Pavel Švec Vendula Pachlová Stanislav Kráčmar 《Food microbiology》2010
The aim of the work was to describe the development of selected biogenic amines (histamine, tyramine, putrescine and cadaverine) in 4 layers of Dutch-type cheese (Edam-cheese) depending on 3 ripening/storage regimes during a 98-day period. Biogenic amines were analysed by means of ion-exchange chromatography. A further goal was to identify microbial sources of biogenic amines in the material analysed. Phenotype characterization and repetitive sequence-based PCR fingerprinting were used to identify the isolated bacteria. The highest content of tyramine, putrescine and cadaverine was determined in cheeses stored in a ripening cellar at a temperature of 10 °C during the whole observation period. Lower biogenic amines content was determined in samples which were moved into a cold storage device (5 °C) after 38 days of storage in a ripening cellar (10 °C). The lowest concentrations of biogenic amines were detected in cheeses which were moved into a cold storage device (5 °C) after 23 days of storage in a ripening cellar (10 °C). During the 98-day period, histamine was not detected in any of the regimes. Within the cheeses analysed, non-starter lactic acid bacteria Lactobacillus curvatus, Lactobacillus casei/paracasei and Lactobacillus plantarum were detected as the main producers of the biogenic amines tested. In starter bacteria Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris the decarboxylase activity tested was not detected. 相似文献
79.
K. Arve J. Adam O. Simakova L. Čapek K. Eränen D. Yu. Murzin 《Topics in Catalysis》2009,52(13-20):1762-1765
The reduction of NO with octane under lean conditions was examined over gold supported on alumina and titania and over alumina supported bimetallic gold–silver catalysts. The silver loading was either 1.2 or 1.9 wt% whereas 0.3, 1 or 5 wt% gold was used. The catalysts were characterized by means of EDXS, N2-adsortion, UV–Vis and TEM to correlate recorded results with different preparation methods. UV–Vis measurements indicated that gold was present in the form of fine Au particles, single Au ions and small (Au)n δ+ clusters on the catalysts and silver was mainly present in the form of single Ag ions. The highest NO to N2 reduction activity was recorded over the 0.3Au–Al2O3 catalyst. The Au–TiO2 catalysts did not result in significant NO to N2 reduction. 相似文献
80.
Alisa Šehić Jelena Vasiljević Andrej Demšar Mirjam Leskovšek Vili Bukošek Jožef Medved Marija Čolović Ivan Jerman Barbara Simončič 《应用聚合物科学杂志》2019,136(5):47007
Polyamide 6 (PA6) composite filament yarns were produced by the simultaneous incorporation of melamine cyanurate (MeCy) with multiwalled carbon nanotubes (CNTs) and carbon black (CB) into a composite matrix in a melt-spinning process. The results show that the simultaneous incorporation of MeCy with CNTs or CB additives provided filaments with a uniform black color. Tensile analysis confirmed that a reinforcing effect was achieved when CB was used, whereas the CNTs induced a reducing effect on the filament tenacity. With regard to the burning behavior, the flame-retardant action of MeCy was preserved in the presence of CB but was significantly hindered when used in combination with CNTs. These results indicate that the mixture of MeCy and CB was much more compatible for the production of reinforced PA6 composite filaments with increased thermal stability and improved flame retardancy over those of the MeCy and CNTs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47007. 相似文献