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991.
992.
Sagirkaya H Misirlioglu M Kaya A First NL Parrish JJ Memili E 《Reproduction (Cambridge, England)》2006,131(5):895-904
Expression of embryonic genes is altered in different culture conditions, which influence developmental potential both during preimplantation and fetal development. The objective of this study was to define the effects of culture conditions on: bovine embryonic development to blastocyst stage, blastocyst cell number, apoptosis and expression patterns of a panel of developmentally important genes. Bovine embryos were cultured in vitro in three culture media containing amino acids, namely potassium simplex optimization medium (KSOMaa), Charles Rosenkrans 1 (CR1aa) and synthetic oviductal fluid (SOFaa). Apoptosis in blastocysts was determined by TUNEL assay and expression profiles of developmentally important genes were assayed by real-time PCR. In vivo-produced bovine blastocysts were used as controls for experiments determining gene expression patterns. While the cleavage rates did not differ, embryos cultured in SOFaa had higher rates of development to blastocyst stage (P < 0.05). Mean cell numbers and percentages of apoptotic cells per blastocyst did not differ among the groups. Expression of the heat shock protein 70 (Hsp70) gene was significantly up-regulated in both CR1aa and KSOMaa when compared with SOFaa (P < 0.001). DNA methyltransferase 3a (Dnmt3a) expression was higher in embryos cultured in CR1aa than in those cultured in SOFaa (P < 0.001). Expression of interferon tau (IF-tau) and insulin-like growth factor II receptor (Igf-2r) genes was significantly up-regulated in KSOMaa when compared with CR1aa (P < 0.001). Gene expression did not differ between in vivo-derived blastocysts and their in vitro-derived counterparts. In conclusion, SOFaa supports higher development to blastocyst stage than KSOMaa and CR1aa, and the culture conditions influence gene expression. 相似文献
993.
In this paper, a new method for sensorless vector control of a permanent magnet synchronous motor (PMSM) using a fuzzy logic observer is developed. This method is based on determination of rotor position and thereby speeds by estimating back-emf components which result from fuzzy logic observers. The rotor position angle and rotating speed are estimated by evaluating the instantaneous values of stator voltages and currents. The estimators are two fuzzy logic observers. They have two inputs: the estimated stator currents and the difference between the measured and estimated stator currents. In addition, the outputs of the fuzzy logic observers are the back-emf components in an – reference frame. The proposed method was implemented using a MATLAB/Simulink software package program. The obtained results are within acceptable error limits for a wide speed range, from 40 rad/s up to 500 rad/s. 相似文献
994.
M. L. Öveçoglu O. N. Senkov N. Srisukhumbowornchai F. H. Froes 《Metallurgical and Materials Transactions A》1999,30(13):751-761
Prealloyed, gas-atomized (GA) Ti−47Al−3Cr alloy powder, containing about 70 pct of the α2 (Ti3Al) phase and 30 pct of the γ (TiAl) phase, was fully amorphized by mechanical alloying. The amorphous phase was stable during
heating to 600°C, but decomposed at higher temperatures, with an exothermic reaction peak at 624°C as the material transformed
to a mixture of α2 and γ and then to a fully γ structure at 722°C. A nanocrystalline compact with a mean grain size of 42 nm was obtained by
hot isostatic pressing (HIP'ing) of the amorphous powder at 725°C. Isothermal annealing experiments were conducted in the
two-phase α+γ field, at 1200°C, using holding times of 5, 10, 25, and 35 hours, followed by air cooling. The X-ray diffractometry
and analytical transmission electron microscopy investigations carried out on annealed and air-cooled specimens revealed only
the presence of the γ grains, which coarsened on annealing. Initially, the grains grew, followed by a saturation stage after
annealing for 25 hours, with a saturation grain size of about 1 μm. This grain growth and saturation behavior can be described
with a normal grain growth mechanism in which a permanent pinning force is taken into account. Twins formed in the γ grains
as a result of annealing and air cooling and exhibited a common twinning plane of (111) with the matrix phase. The minimum
γ grain size in which twinning occurred in the annealed specimens was determined to be 0.25 μm, which suggests that twinning
is energetically unfavorable in the nanometer-sized grains.
N. SRISUKHUMBOWORNCHAI, formerly Master's Student, IMAP, University of Idaho 相似文献
995.
Duygu Ağaoğulları Hasan Gökçe İsmail Duman M. Lütfi Öveçoğlu 《Journal of the European Ceramic Society》2012,32(7):1457-1462
In this study, AlB2 powders were synthesized by using a combined method of mechanical alloying (MA) and annealing of elemental aluminum (Al) and boron (B) powders. Milling was performed in a planetary ball-mill (Fritsch? Pulverisette 7 Premium Line) up to 15 h under argon (Ar) atmosphere. Annealing process was carried out in a tube furnace at 650 °C for 6 h under Ar atmosphere. The effects of MA durations on the annealing process and AlB2 formation were investigated. The conversion of Al and B powders to AlB2 starts after only MA for 3 h or after MA for 1 h and subsequent annealing. A slight formation of AlB12 occurs at 242 °C for as-blended powders and it shifts to about 272 °C for MA’d powders. Al–B powder blends MA’d for 9 h and annealed have AlB2 particles in size between 35 and 75 nm in the presence of Al13Fe4, Fe3B and Fe2B contaminations. 相似文献
996.
997.
Seyed Mohammad Hossein Hosseini Markus Merkel Andreas Öchsner 《Materials Letters》2009,63(13-14):1135-1137
This paper investigates the thermal properties of a new type of hollow sphere structures. For this new type, the sphere shell is perforated by several holes in order to open the inner sphere volume and surface. The effective thermal conductivity of perforated sphere structures in a primitive cubic arrangement is numerically evaluated for different hole diameters and different dimensions of the joining elements. 相似文献
998.
E. Vierlinger ÖVE 《e & i Elektrotechnik und Informationstechnik》1999,116(11):665-669
Ohne Zusammenfassung 相似文献
999.
Günther Brauner ÖVE 《e & i Elektrotechnik und Informationstechnik》1999,116(7-8):405-405
1000.
Yesim Özogul Fatih Özogul A. Ilkan Olgunoglu 《European Food Research and Technology》2005,221(3-4):547-549
AbstractThe fatty acid and mineral compositions in the flesh of wild snail (Helix pomatia) collected in the region of Cukurova in Turkey were evaluated. Proximate analysis of snails showed that they are rich in protein (18%) and low in lipid (0.49%). The main fatty acids detected were C16:0 (12%) C18:0 (19%), C22:0 (7%), C18:1 n–9 (17%), C18:2 n–6 (16%) and C20:2 n–11.14c (10%). The total SFA, MUFA and PUFA content of lipids were 37.87, 19.65 and 25.83% of total fatty acids, respectively. The major minerals found were Ca, P, K, Mg and Na. However, Fe, Mn and Zn contents of snail meat are less than 2 mg/100 g. The results of this study have showed that snails are good sources of protein and minerals. 相似文献