[en] Four related subjects representing a series of investigations on the theory of elementary particles in a curved space are examined; however, related subjects in flat space and on the nonlinear theory of gravitation are also included. Part I is devoted to massive and massless spin-2 fields in de Sitter space. Linearized Einstein's field equations with cosmological terms are reconstructed from the particle physicist's point of view based on the de Sitter space-time background. In Part II the nonlinear theory of the massless spin-2 fields is constructed, and this question is discussed from the point of view of a deformation of the gauge group. In an appendix and Part III the wave equations for massless fields with any spin in flat space are presented. In Part IV these wave equations are immediately generalized for integer spin to de Sitter space

[en] Mullite has many excellent properties which can produce refractories with high quality. The fast transformation of andalusite into mullite and silica is around 1653K. In this work, quenching method was employed to study the effect of Y2O3 additive on the transformation of andalusite into mullite. The experiment was carried out in a closed tube furnace at 1553K and 1573K. The transformation of andalusite into mullite was studied thermodynamically. Thermodynamic calculation reveals that the temperature of spontaneous mullitization of andalusite was 1180K. Additional Y2O3 of 3.75wt% was added into different sizes of andalusite powders. Some Y2O3 was found to be reacted with SiO2 and formed as Y2Si2O7 phase. The mullite contents after fired at both 1523K and 1573K for 2h have improved markedly when the andalusite powders were with small sizes (d50=4μm and d50=43μm) but little affection on the mullitization of andalusite with large size (d50=143μm) was found. Moreover, with the addition of Y2O3, the andalusite (d50=4μm) was completely transformed into mullite after fired at 1573K for 2h. The mullite content in the sample of small size after fired at 1573K went up by more than 20%. The viscosity value of generated liquid phase is major determinants of transformation of andalusite into mullite.

[en] The temperature and field dependencies of isothermal current-voltage curve of an epitaxial YBa₂Cu₃O_7-δ thin film have been measured. The current-induced dissipation shows two crossovers: one is from independent on transport current to dependent on one, corresponding to the transition from free flow to thermally activated flux flow, and another is from upward curvature on current to downward one, corresponding to the transition from pinned vortex liquid state to vortex solid state. Compared with the R-T measurement, we find that the transition from independent on the transport current to dependent on one is close to the melting transition of vortex lattice. The temperature dependence of the effective pinning energy has been discussed

[en] Afatoxin B1 (AFB1) is the most toxic form among the mycotoxins. Cytokines are important mediators of the immune system. T-cell subsets play a crucial role in cell-mediated immunity. The aim of present study was to evaluate the effects of dietary AFB1 on the cytokines expression and T-cell subsets in the cecal tonsil of broiler chickens throughout a 21-day experimental period. One hundred and fifty six one-day-old broiler chickens were randomly divided into control group (0 mg AFB1/kg feed) and AFB1 group (0.6 mg pure AFB1/kg feed). At 7, 14 and 21 days of age, the levels of seven cytokines (IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ and TNF-α) mRNA expression as well as the proportions of T-cell subsets (CD3+, CD3+CD4+, CD3+CD8+) by qRT-PCR and flow cytometry methods were assessed in the cecal tonsils. The levels of the seven cytokines mRNA expression and the percentages of T-cell subsets significantly decreased at 14 and 21 days of age in the AFB1 group compared with the control group. However, the CD4+/CD8+ ratio was not significantly changed. These results demonstrate that 0.6 mg/kg AFB1 dietary exposure reduced the levels of cytokines mRNA expression and the percentages of T-cell subsets in the cecal tonsils of broiler chickens, suggesting that the cell-mediated immunity of cecal tonsils might be impaired in broilers. (Author)

[en] MgB₂/Cu tapes were fabricated by power-in-tube technique using MgB₂ superconducting powder and no post-annealing treatment was performed for the prepared tapes. Both X-ray diffraction and scanning electron microscopy results indicate that there is no obvious texture of grains for the tape samples. However, compared with the bulk sample, evident shifting and broadening of diffraction peaks is observed and T_c is reduced for the tape samples. In addition, it is found that there exists a remarkable difference in flux pinning ability for tapes prepared using wires with different diameters. The difference seems to originate from the different strain and microstructure defects of MgB₂ grains caused by cold working

[en] This paper presents an automatic procedure of pseudo-colour encoding of moire fringe orders. A carrier consisting of parallel fringes is introduced before the specimen deforms. The carrier pattern is captured by a camera and then stored in computer as a standard image. The space of the carrier fringes is distored by the strains on the specimen as it is loaded. On a certain condition, the orders of the frequency-modulated carrier still vary monotonically so that they can be easyly distinguished. Both the standard fringe-carrier and the frequency-modulated fringe pattern are transformed into two digital images, of which every fringe is encoded by one of the pseudo-colour codes corresponding to the monotonical fringe orders. At each pixel, the difference between the colour sequences of two images is calculated to obtain the fringe order of pure deformation. The moire pattern of the in-plane displacement is restored as a pseudo-colour image by whose colour-change the variation of the fringe orders is displayed. (orig.)

[en] This paper considers a physical model for a plasma-sheath with a periodical forced oscillation. A numerical study of the equation of the plasma-sheath has been carried out. It has been found that the three well-known transition routes to chaos coexist in the model and are attributed to separate variation of the control parameters. The authors discuss the relation between the results and physical processes and point out that these intrinsic stoichastic account for the principal processes leading to plasma instability in some plasma devices (e.g., plasma ion sources for electromagnetic isotope separators)

[en] The Fierz-Pauli program is carried out for spin-2 in de Sitter space. A spin-s field is associated with an irreducible representation D(E₀,s) of the universal covering group of SO(3,2), with external weight (L₀₅,L₁₂)→(E₀,s). (L₀₅ is the time translation operator). The particular cases D(s+1,s)(s=1,2,...) are characterized by invariance of the field equations under a gauge group and is for this and other reasons called 'the massless case'. The Fierz-Pauli program is carried out for s=2, E₀>3; it fails in the special case E₀=3 only. The limit,as E₀→3, of the Fierz-Pauli field equation agrees with the linearized form of Einstein's gravitational field equation, with cosmological constant lambda=3rho. Here rho is the curvature constant of de Sitter space and the linearization referred to is defined relative to the de Sitter metric. (Auth.)

[en] The low-frequency (f) AC loss per cycle of a high-temperature superconducting Bi-2223/Ag tape is frequency independent when the measurements are performed at 77 K with current amplitude I_m below the critical current I_c. Its loss vs. I_m/I_c is consistent with the results derived from the critical state model with a Kim type field dependent critical current density J_c. After I_c of the sample is degraded from 32 to 16.5 A by repeated cooling and warming, the loss becomes strongly f dependent and it increases by a factor of 2-3 with decreasing f from 405 to 15 Hz. It is found that by defining an effective critical current I_c1, which increases from 14 to 25 A with increasing f from 15 to 405 Hz, the Norris result for an elliptic bar with a Bean type J_c fits the data for all values of f. This behavior indicates that the I_c degradation results from the division of as-obtained wide Josephson junctions into fine ones, and the thermally activated creep of Josephson vortices formed in the system of fine junctions leads to a frequency dependent I_c1

[en] To compare the clinical efficacy of minimally invasive percutaneous lag screw internal fixation and reconstruction plate in the treatment of unstable pelvic fractures. Study Design: An experimental study. Place and Duration of Study: The Department of Orthopaedics, Second People's Hospital of Liaocheng, Linqing City, China, from January 2016 to March 2018. Methodology: A total of 130 patients with unstable pelvic fracture were randomly divided into group A and group B, with 65 cases in each group. Group A was treated with minimally invasive percutaneous lag screw internal fixation, and group B was treated with reconstruction plate. Clinical efficacy of two groups after treatment was evaluated. Serum alkaline phosphatase (ALP), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), stress hormones cortisol (Cor), angiotensin II (Ang II), and norepinephrine (NE) contents were compared. Results: After treatment, the excellent and good rate in group A was higher than that in group B (p=0.005). At 7 days after the operation, serum ALP level in group A was higher than that in group B (p <0.001), serum TNF-α, CRP, Cor, Ang II, and NE levels were lower in group A than those in group B (all p <0.001). Conclusion: Compared with reconstruction plate, minimally invasive percutaneous lag screw internal fixation has better clinical efficacy in patients with unstable pelvic fractures; meanwhile, it can effectively increase serum ALP level, reduce the levels of inflammatory cytokines TNF-α and CRP, and effectively reduce surgical trauma as well as postoperative body stress response. (author)