Results 21 - 30 of 88
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[en] Si nano-well arrays, with precisely controlled undercut Si sidewall profiles and flat bottomed pockets, enable uniform nanoscale pattern transfer from resists to metal deposits without degradation of the initial lithographic resolution, as verified by the formation of arrays of Au nano-dots with 10 nm diameter. An additional functionality of the Si nano-wells as local nano-reactors, where the patterned material is enclosed in a Si pocket during high temperature reaction, is demonstrated by thermally inducing a phase transformation of the as-deposited A1 phase of FePt nano-dots to the high coercivity, chemically ordered L10 phase.
[en] The heavy fragments in heavy-ion collisions are finally formed after the hot prefragments undergo sequential decay, of whom the temperature should be much lower than that of prefragments. Using the double ratio (DR) method, the isotopic thermometer (Tiso) for heavy fragment is constructed using the yield of heavy isotopes. Tiso of heavy fragment is obtained by analyzing the measured data in the 1A GeV 124,136Xe and 140A MeV 48Ca/64Ni reactions. Result shows that Tiso varies from 0.5 MeV to 10 MeV. But most Tiso is around 1 ± 0.5 MeV, which is much lower than temperature of light particles. Result also indicates that the difference between Tiso of heavy fragments in different reactions is very small, and Tiso is independent on the size of the reaction system, the incident energy and the neutron-richness of the projectile. (nuclear physics)
[en] Daphniopsis tibetana Sars lives in elevation, usually with strong solar UV radiation. We speculate that UV may have an effect on the ecology and evolutionary biology of this species. However, the regulatory effect and mechanism of UV on D. tibetana have not been studied previously. Here, our results showed that UVB could act as a positive factor in the relative body lengths, reproductive parameters, and population growth parameters of D. tibetana when UVB radiation is 20–170 mJ cm−2, compared with the control group. Strikingly, these parameters were highest at 120 mJ cm−2. To explore the mechanism underlying the UVB irradiation effects, we conducted a transcriptome analysis using the Trinity platform. The results indicated that differentially regulated genes were mostly enriched in lipid transport and lipid localization by Gene Ontology (GO) enrichment analysis of 146 differentially expressed genes (83 upregulated and 63 downregulated). This is the first study of UVB radiation of D. tibetana to reveal genes that may have crucial roles in survival, growth, and reproduction and could be candidates for future functional studies. Additionally, the study could supply a substantial resource for investigating and elucidating lipids that could play important roles in a physiological context.
[en] Isoscaling and isobaric yield ratio difference (IBD) methods are used to study Δμ/T (Δμ being the difference between the chemical potentials of the neutron and proton, and T being the temperature) in the measured 1 A GeV 124Sn + 124Sn, 112Sn + 112Sn, 136Xe + Pb and 124Xe + Pb reactions. The isoscaling phenomena in the 124Sn/112Sn and 136Xe/124Xe reaction pairs are investigated, and the isoscaling parameters α and β are obtained. The Δμ/T determined by the isoscaling method (IS-Δμ/T) and the IBD method (IB-Δμ/T) in the measured Sn and Xe reactions are compared. It is shown that in most fragments, the IS- and IB-Δμ/T are consistent in the Xe reactions, while the IS- and IB-Δμ/T ones are only similar in the less neutron-rich fragments in the Sn reactions. The shell effects in IB-Δμ/T are also discussed. (paper)
[en] A granular magnetic material, Co-Fe-Hf-O, has been developed-using dc pulsed magnetron reactive sputtering. The deposition rate is as high as 1.3 nm/s. The electrical and magnetic properties of Co-Fe-Hf-O film can be tuned by changing O2 during deposition. A highly resistive, magnetically soft film has been achieved in a small range of the O2/(Ar+O2) gas flow ratio. The origin of the dependence of magnetic and electrical properties of this material is studied and explained by monitoring the evolution of the film microstructure, using x-ray diffraction and transmission electron microscopy
[en] The intensity distribution in Fresnel diffraction through a slit includes numerous small fluctuations referred to as ripples. These ripples make the modelling of the intensity distribution complicated. In this study, we examine the characteristics of the Fresnel diffraction intensity distribution to deduce the rule for the peak position and then propose two types of quantum-mathematical models to obtain the distance between the edge and the peak point. The analysis and simulation indicate that the error in the models is below . The models can also be used to detect the edges of a diffraction object, and we conduct several experiments to measure the slit width. The experimental results reveal that the repetition accuracy of the method can reach . (paper)
[en] Collisions of 1.2 A GeV Ar on KCl in the Bevalac Streamer Chamber are studied using two methods: azimuthal distribution analysis and azimuthal correlation function analysis. Comparing with the Vlasov-Uehling-Uhlenbeck model predictions for different nuclear equations of state, the stiffness of the high density nuclear matter is estimated. The maximum azimuthal anisotropy inferred from the azimuthal distribution method is decreased by about 30% because of dispersion of the azimuthal angle of the reaction plane. This distortion can be eliminated by using the azimuthal correlation function analysis proposed in this paper
[en] The effect of multi-pion correlations on two-pion interferometry in a mulri-pion event is studied. A new general two-pion interferometry method is developed, by taking into consideration of the effect of multi-pion correlations. Data for 1.8 A GeV Ar + Pb central collisions at the Bevalac streamer chamber are analysed by using this new method
[en] By in situ x-ray diffraction, an isostructural phase transition between two kinds of the cubic PbCrO_3perovskites at around 1.6 GPa and room temperature with a 9.8% volume change is discovered. Recently, we have synthesized this cubic PbCrO_3perovskite successfully. Here we report our high-pressure in situ electrical resistance measurements up to 4.1 GPa for this perovskite sample. At room temperature, the resistance shows special changes at 1.2 and 2.7GPa. They may indicate the starting and ending points of this transformation. At 4.1 GPa, the negative temperature resistance coefficient is observed, which means that phase II could be considered as a semiconductor according to our present measurement
[en] The effect of absorption correlation on the analyzed results of pion interferometry is studied. The way to remove this effect is discussed by using the data from VUU simulation. The data for collisions of 1.8 A GeV Ar+Pb at the Bevalac streamer chamber are analyzed. The spatial parameter of the source extracted from pion interferometry is less than the true value due to the absorption correlation. The effect of absorption correlation can be eliminated by properly constructing the background