Results 1 - 10 of 18
Results 1 - 10 of 18. Search took: 0.014 seconds
|Sort by: date | relevance|
[en] We describe a method for preparation of crystalline silver telluride films by cathodic deposition from dimethyl sulfoxide (DMSO) solutions containing 0.1 M NaNO3, 5.0 mM AgNO3 and 3.5-7.0 mM TeCl4. X-ray diffraction data indicated that the deposited silver telluride films could be adjusted from Ag excess and stoichiometric monoclinic Ag2Te to hexagonal Ag7Te4 by increasing the concentration of TeCl4 in the electrolyte or lowering the deposition potential. The Ag2Te film is gray and the Ag7Te4 film is dark blue-gray and mirror like adhered strongly to the substrates. Scanning electron microscopy images show that Ag2Te films were formed with globular grains with average diameters of more than 1 μm. In contrast, Ag7Te4 film consists of triangles characteristic of a (1 1 1) single-crystal with a hexagonal structure in average sizes of about 0.4 μm. The X-ray photoelectron spectra (XPS) indicated that the binding energies deviation of Te3d in Ag7Te4 is less than that in Ag2Te, which is consistent with the apparent valences of Te in Ag2Te and Ag7Te4. Finally, the cathodic deposition reactions were studied by cyclic voltammetry
[en] While b.c.c. metals deform plastically by dislocation motion or deformation twinning, the atomistic mechanisms governing the choice of deformation modes are not well established. Molecular dynamics simulations using the Finnis-Sinclair potential were carried out to explore the pressure dependence of the deformation response of b.c.c. molybdenum. The crystal was sheared in (1 1 2)[1-bar 1-bar 1] under various confining pressures. The homogeneous nucleation stress of deformation twinning was found to increase with increasing confining pressure. Under sufficient pressure (0 1 1)[1-bar 1-bar 1] dislocations were nucleated instead of twins. Details of the dislocation and twin nucleations were analyzed with the help of the multi-layer generalized stacking fault energies. A two-fault (n=2) metastable twin state was found, in contrast to previous results using pair potentials
[en] Objective: To assess the effect of snapshot freeze (SSF) motion correction algorithm on the image quality of coronary CT angiography (CCTA). Methods: Thirty-one consecutive patients underwent coronary CTA without heart rate control. All of the CCTA images were reconstructed by the means of both standard (STD) and SSF motion correction. Image quality and interpretability of STD and SSF reconstructions were compared. CCTA images were interpreted with Likert 4-points score system by two experienced radiologists. The image qualities were assessed on per-artery and per-segment level, and interpretability was performed on per-segment, per-artery, and per-patient levels. Comparisons of variables were performed with paired Wilcoxon rank sum test and paired Chi-square test. Results: SSF reconstructions showed higher interpretability than STD reconstructions on per-patient [100.0% (31/31) vs 64.5% (20/31), χ"2=9.09, P=0.002] and per-artery [100.0% (124/124) vs 83.9% (104/124), χ"2=18.05, P=0.001] and per-segment level [99.0% (413/417) vs 89.2% (372/417), χ"2=35.56, P=0.001]. Image qualities were higher with the use of SSF than STD reconstructions on LAD [3.3 ± 0.7 vs 2.9 ± 1.0, Z=2.70, P=0.007], LCX [3.1 ±0.8 vs 2.5 ± 1.1, Z=3.23, P=0.001] and RCA [3.3 ±0.6 vs 2.1 ± 0.9, Z=4.60, P=0.001], but they were similar on LM [3.9 ± 0.4 vs 3.7 ± 0.6, Z=1.89, P=0.059]. Image quality was higher with the use of SSF versus STD reconstructions on per-segment [3.5 ± 0.7 vs 3.0 ± 1.0, Z=10.31, P=0.001] level. Conclusions: The use of SSF motion correction algorithm improves image quality and interpretability of coronary CTA without heart rate control. (authors)
[en] Objective: To evaluate effects on image quality and effective radiation with the dose reduction protocol adapted by body mass index (BMI) in coronary artery CT angiography with discovery 750 HD. Methods: Two hundred and seven patients suspected with coronary artery disease (CAD) were enrolled in Group A who were underwent CT angiography with routine radiation, and another 242 patients were enrolled in Group B who received a new scanning protocol with tube voltage and tube current modulation depending on the BMI. The scores of image quality, signal noise ratio(SNR), CT dose index (CTDIvol), and effective dose (E) were compared and the correlation between the scanning parameters and E was analyzed. Results: The mean radiation dose in Group B(1.2, ranging from 0.8 to 2.5 mSv) was significantly lower than that in Group A(1.9, ranging from 1.5 to 2.3 mSv; Z = -6.24, P < 0.05). The multivariate regression analysis revealed that the first factor affecting effective radiation dose ranked as scanning mode, tube voltage, tube current, and scan length, respectively. The image quality between two groups was not significantly different. The SNR in Group B was greater than that in Group A (Z = -2.22, P < 0.05). Conclusions: Dose reduction protocol in coronary artery CT angiography with discovery 750 HD would help to reduce the radiation dose effectively without sacrificing image quality. (authors)
[en] The problem of delay-dependent asymptotic stability criteria for neural networks (NNs) with time-varying delays is investigated. An improved linear matrix inequality-based delay-dependent stability test is introduced to ensure a large upper bound for time-delay. A new class of Lyapunov functional is constructed to derive some novel delay-dependent stability criteria. Finally, a numerical example is given to demonstrate the effectiveness of the proposed method.
[en] Let be rotations on the unit circle and define as for , , where is the shift, and and are rotational angles. It is first proved that the system exhibits maximal distributional chaos for any (no assumption of ), generalizing Theorem 1 in Wu and Chen (Topol. Appl. 162:91–99, 2014). It is also obtained that is cofinitely sensitive and -sensitive and that is densely chaotic if and only if .
[en] A facile and green method was employed to prepare large-scale free-standing TiO2 nanotube (TNT) arrays, in which as-anodized TiO2 nanotube films prepared in organic electrolytes with thickness ranging from seven to tens of micrometers were then ultrasonicated in a mix solution of ethanol and water. By controlling the ratio of ethanol to water, the time and the power of ultrasonication, large-scale free-standing TiO2 nanotube arrays without any crack could be detached from the Ti substrates. Hydrogen sensing results demonstrated that the free-standing TNT film is more sensitive than a film with Ti substrates when exposed to 1000 ppm hydrogen ambient
[en] Highly branched gold nanoflowers are synthesized in high yield by a simple amino-reducing method, without additional seeds or surfactant agents. We present a systematic investigation of the influence of different parameters on the size, morphology, and monodispersity of gold nanoflowers. The initial concentration of reducing agent, the solvent viscosity, and the reaction temperature play critical roles in the formation of nanoparticles. A lower concentration of reducing agent causes larger particles with sharp and dendritic tips. Moreover, with increasing solvent viscosity, the obtained particles have more and larger tips. Examination of the nanoparticles at different reaction stages with transmission electron microscopy and UV-vis spectroscopy reveals the formation of the gold nanoflowers as a classical growth process in which diffusion-controlled growth gives rise to the highly branched structures. Additionally, these gold nanoflowers have prospects for surface-enhanced Raman scattering (SERS) imaging because of their strong SERS enhancement and clean surface.
[en] In spite of being sheared along the so-called pseudo-twinning [2-bar 11] direction, γ-TiAl undergoes true twinning under zero pressure or hydrostatic tension by means of a specific combination of 1/6 [2-bar 11], 1/6 [1-bar 21-bar ] and 1/6 [1-bar 1-bar 2] shears in two consecutive (1 1 1) matrix planes allowing the adjacent twin to thicken over one (1 1 1) atomic layer. The corresponding total shear strain of 2√(2) is four times as large as that generated by conventional deformation twinning or during the L10 to L11 transformation by 1/6 [112-bar ] or 1/6 [2-bar 11] shears, respectively. This shear is substantially more effective in accommodating stress concentration and high strain rate than conventional deformation twinning. The conditions under which twinning by 2/3 [2-bar 11] dislocations operates are interpreted based on a modified gamma-surface and discussed in terms of zonal partial dislocations
[en] In this paper, effect of fast-neutron and X-rays on the expression of P53 and CyclinB1 in small intestinal tissues of mice were investigated. The mice were randomly grouped and sacrificed 6 h after irradiation. Western blot assay was applied to detect the p53 and CyclinB 1 expressions, and flow cytometry was used to monitor changes in the small intestinal cell cycle. The results showed that the expression levels of p53 increased with irradiation dose. The expression levels of CyclinB 1 increased with the dose at first, but decreased when the dose exceeded 0.28 Gy. The results from the flow cytometry showed that the amount of cells in G2/M phase increased with the dose in both occasions. It was concluded that the low doses of fast-neutron and X-rays can make the expression levels of p53 and CyclinB 1 increase, but the expression levels of CyclinB 1 decreased and the G2 arrest occurred with increased doses. (authors)