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The breakdown voltage (Vb) was studied for (Bi0.5Na0.5)TiO3 (BNT)-added positive temperature coefficient of resistance (PTCR) ceramic samples based on (Ba0.659Pb0.341)TiO3, which were prepared by a traditional solid-reaction method and sintered in an air atmosphere. By measuring the electrical properties and microstructures of the materials, the breakdown voltage was found to depend on neither the room-temperature resistivity nor the maximum resistivity, but on the grain size (D) of the samples to some extent. With a decrease in the grain size, the Vb value increases rapidly, especially for samples with fine grains. With the help of Heywang-Jonker theory, the depletion width (LD) was calculated to determine the dominant factor affecting the Vb value using the approximate equation Vb= 600 × LD/D + 100; i.e., the breakdown voltage is approximate directly proportional to the ratio of LD/D. However, the room-temperature resistivity increased slightly with LD/D, and the PTC performance remained at a high level (α > 34%, Rmax/Rmin > 1 × 103). It is more advantageous to increase the breakdown voltage by adjusting LD/D than by reducing grain size alone. The variations in the grain size and the depletion layer width of different samples are mainly due to the generation of VNa′ and VBiʺ′ inside of the lattice. The ratio of LD/D can also be used to explain the variation in room-temperature resistivity. [ABSTRACT FROM AUTHOR]

To discover the optimal relaxation parameter and related smoothing factor in multigrid method, smoothing properties of distributive relaxation for Stokes flow are investigated by local Fourier analysis (LFA) in multigrid method. As discretizing Stokes operator on the staggered grid, the measure of hellipticity is computed to prove the discrete system is stable. Then the distributive relaxation for discrete Stokes system is developed. It is shown that the smoothing factor of the discrete system is determined by Poisson operator. Finally, with red-black Jacobi point relaxation, the optimal one-stage relaxation parameter and related smoothing factor are presented by LFA. The result proves theoretically the rationality of the existing control parameters, which provides a theoretical reference for improving the efficiency of multigrid computation and parameter selection, and is significant for improving the accuracy of flow numerical simulation. [ABSTRACT FROM AUTHOR]

Abstract: ZnO thin films were prepared on glass or on homo-buffer/glass by a RF magnetron sputtering method at RF power of 100–550W. The structural and Raman characteristics of the films were analyzed by X-ray diffraction and Raman scattering. There appeared a sharp peak of 1080.2cm−1 near the A1(2LO) mode (1156cm−1) of ZnO in the Raman spectra when the RF power was higher than 300W. In this case, the (100) peak of ZnO film appeared obviously. It was speculated that the Raman mode at 1080.2cm−1 was induced by the ordered distribution of Zn i defects in ZnO lattice. [Copyright &y& Elsevier]

The ZnO thin films with preferential C-orientation and smooth surface have been prepared using an RF magnetron sputtering method by the insertion of low-power (LP) sputtered ZnO buffer. The XRD results show that the C-orientation of the ZnO buffer layer deposited under the RF power of 30 W is much better than that deposited under higher RF power. With the increase of the LP-buffer thickness, the C-orientation as well as the crystal quality of ZnO films improves, the surface becomes smooth and the RMS roughness decreases from 88.4 Å to 38.5 Å. The ZnO lattice is independent of the insertion of LP buffer. [ABSTRACT FROM AUTHOR]

Neodymium doped yttrium aluminum garnet (Nd:YAG) transparent ceramics were fabricated from Nd:YAG nanopowders synthesized via a reverse precipitation method by vacuum sintering and successive hot isostatic pressing (HIP) post-treatment. The powders obtained by calcining the precursor at 1100 °C for 4 h and then ball milling for 2 h with 0.5 wt% TEOS as sintering aid were used to fabricate Nd:YAG ceramics. The green bodies were vacuum sintered at 1500–1800 °C for 10 h, followed by the HIP at 1600 °C for 3 h in 200 MPa Ar atmosphere. Influence of the calcination temperature on the phase, morphology and particle size evolution of the nanopowders, as well as the optical transparency and microstructure of the obtained Nd:YAG ceramics before and after the HIP post-treatment was investigated in detail. It was found that for the post-treated 1800 °C-vacuum-sintered Nd:YAG ceramic sample, the in-line transmittance increased from 48.0% up to 81.2% at the lasing wavelength of 1064 nm. [ABSTRACT FROM AUTHOR]

Objective: To investigate the treatment method of senile patients with femoral intertrochanteric fractures and its clinical outcomes., Methods: From January 2005 to December 2007, 192 senile patients with femoral intertrochanteric fractures were treated, including 85 males and 107 females aged 65-92 years old (average 75 years old). The injury was caused by fall on walking in 106 cases, fall when riding a bicycle in 55 cases, and traffic accidents in 31 cases. According to Evans classification, there were 12 cases of type I A, 43 cases of type I B, 29 cases of type II, 24 cases of type III A, 23 cases of type III B, 26 cases of type IV, and 35 cases of type V. One hundred and fifty patients were associated with cardio-cerebrovascular diseases, 120 patients were complicated with chronicle hypertension, 90 cases were associated with bronchitis, and 75 cases were complicated with diabetes. The time from injury to hospital admission was 1 hour to 14 days. Among those patients, 108 were treated with conservative treatment, 68 received dynamic hip screw (DHS) fixation, and 16 underwent proximal femoral Gamma nail fixation., Results: All the patients were followed up for 12-36 months (average 18 months). The fracture all reached bone union without occurrence of nonunion and delayed union. Patients could take care of themselves, and there were no occurrences of serious pains and dysfunctions. The therapeutic effect was satisfactory. The conservative treatment group: the average hospital stay length was 48 days; the average bone healing time was 14 weeks; 23 cases had different degrees of coxa adducts; Harris score system was adopted to evaluate hip joint function, 45 cases were graded as excellent, 31 as good, 10 as fair, and 22 as poor, and the excellent and good rate was 70.4%. DHS internal fixation group: the average operation time was 60 minutes; the average bleeding volume during operation was 200 mL, the average hospital stay length was 24 days; the average bone healing time after operation was 12 weeks; Harris score system was adopted to evaluate the injured hip joint function, 38 cases were graded as excellent, 21 as good, 8 as fair, and 1 as poor, and the excellent and good rate was 86.8%. Gamma nail fixation group: the average operation time was 70 minutes; the average bleeding volume during operation was 200 mL, the average hospital stay length was 14 days; the average bone healing time after operation was 12 weeks; Harris score system was adopted to evaluate the injured hip joint function, 11 cases were graded as excellent, 4 as good, 1 as fair, and the excellent and good rate was 93.8%., Conclusion: For geriatric femoral intertrochanteric fractures, operative treatment should be performed, the preoperative preparation should be sufficient, and individual-oriented treatment method should be selected on the basis of physical conditions of patients and the types of fractures.