Switchable multiple lasing oscillations in an erbium-doped fiber ring laser using a single stage of a Sagnac loop mirror

A simple scheme for a switchable multi-wavelength erbium-doped fiber (EDF) ring laser is investigated by using a single stage of a Sagnac loop mirror. The multiple lasing outputs are obtained and switched readily by controlling the state of polarization (SOP). Since the transmission characteristics of the Sagnac loop mirror in terms of peak wavelengths and peak powers strongly depend on the SOP, the switching performance of the proposed multi-wavelength EDF laser can be effectively obtained. The proposed multi-wavelength EDF laser has versatile lasing outputs in states of a single-, dual-, triple-, and quadruple-wavelength oscillations. The multiple outputs are effectively switchable by adjusting the SOP.     

固相反应法制备的Gd0.7Sr0.3MnO3粉末的磁学特性

利用固相反应法制备了用Sr部分替换GdMnO3中Gd的锰基钙钛矿氧化物Gd0.7Sr0.3MnO3.X射线衍射表明其晶体结构为正交晶系,空间群为Pnma.通过测量样品在零场冷却和加场冷却下的磁化强度及磁化率随温度的变化曲线,得出样品显示亚铁磁特性,Mn和Gd两个子晶格相互反平行.根据居里-外斯定律得知其居里温度为61 ...     

Charged particle multiplicity in showers formed by gamma-rays in oriented tungsten crystal

It is shown that the average charged particle multiplicity in electromagnetic showers induced by γ-rays with energies of 9–26 GeV in the tungsten crystal 1 mm thick (T = 77 K) oriented along the 〈111〉 axis approximately twofold increases in comparison with a misoriented crystal.     

Lattice study of dense matter with two colors and four flavors

We present results from a simulation of SU(2) lattice gauge theory with N _f = 4 flavors of Wilson fermion and non-zero quark chemical potential μ, using the same 12³×24 lattice, bare gauge coupling, and pion mass in cut-off units as a previous study (S. Hands, S. Kim, J.I. Skullerud, Phys. Rev. D 81, 091502(R) (2010)) with N _f = 2 . The string tension for N _f = 4 is found to be considerably smaller implying smoother gauge field configurations. Thermodynamic observables and order parameters for superfluidity and color deconfinement are studied, and comparisons drawn between the two theories. Results for quark density and pressure as functions of μ are qualitatively similar for N _f = 2 and N _f = 4 ; in both cases there is evidence for a phase in which baryonic matter is simultaneously degenerate and confined. Results for the stress-energy tensor, however, suggest that while N _f = 2 has a regime where dilute matter is non-relativistic and weakly interacting, N _f = 4 matter is relativistic and strongly interacting for all values of μ above onset.     

Antiferromagnetic interactions in Er-doped SnO<Subscript>2</Subscript> DMS nanoparticles

Diluted magnetic semiconductor (DMS) nanoparticles of Sn_1−x Er _x O₂ (x = 0.0, 0.02, 0.04, and 0.1) were prepared by sol–gel method. The X-ray diffraction patterns showed SnO₂ rutile structure for all samples with no impurity peaks. The decrease in crystallite size with Er concentration was confirmed from TEM measurements (from 12 to 4 nm). The UV–Visible absorption spectra of Er-doped SnO₂ nanoparticles showed blue shift in band gap compared to undoped SnO₂. The electron spin resonance analysis of Er-doped SnO₂ nanoparticles indicate Er³⁺ in a rutile lattice and also decrease in intensity with Er concentration above x = 0.02. Temperature-dependent magnetization studies and the inverse susceptibility curves indicated increased antiferromagnetic interaction with Er concentration.     

Simple expressions of the reflection and transmission coefficients of fundamental Lamb waves by a rectangular notch

The scattering of Lamb waves by a two-dimensional rectangular notch is investigated for rapid inspection of defects in a structure. To derive the reflection and transmission coefficients of the scattered waves in a simple way, the scattering caused by the notch is analyzed through the composition of individual scattering processes. Linear equations corresponding to the reflection and transmission coefficients are constructed along with scattering graphs. For an illustration of the efficacy of the presented method, the scattering of fundamental symmetric and anti-symmetric modes are inspected according to the depth and width of a notch in a plate. Validity of these expressions is demonstrated by the comparison of the theoretical analysis results with those from the finite element analysis.     

Estimation of the protonic concentration and mobility in Ba(Zr0.81Yb0.15Zn0.04)O3−δ ceramic

Rare earth doped BaZrO₃ is one of most promising proton conducting oxides as it has high proton conductivity and sound chemical stability. Sintering aids such as ZnO, however, should be incorporated in order to improve poor sinterability. In this study, the effects of adding ZnO on proton conductivity of Yb-doped BaZrO₃ (BZYb) were investigated. From the electrical conductivities measured under various water vapor pressures, concentration and mobility of the proton were obtained. Proton mobility of BZYb with ZnO (BZYb-Zn) was smaller than that of BZYb while hydration enthalpy of BZYb-Zn was more negative than that of BZYb.     

Agglomeration,sedimentation, and cellular toxicity of alumina nanoparticles in cell culture medium

The cytotoxicity of alumina nanoparticles (NPs) was investigated for a wide range of concentration (25–200 μg/mL) and incubation time (0–72 h) using floating cells (THP-1) and adherent cells (J774A.1, A549, and 293). Alumina NPs were gradually agglomerated over time although a significant portion of sedimentation occurred at the early stage within 6 h. A decrease of the viability was found in floating (THP-1) and adherent (J774A.1 and A549) cells in a dose-dependent manner. However, the time-dependent decrease in cell viability was observed only in adherent cells (J774A.1 and A549), which is predominantly related with the sedimentation of alumina NPs in cell culture medium. The uptake of alumina NPs in macrophages and an increased cell-to-cell adhesion in adherent cells were observed. There was no significant change in the viability of 293 cells. This in vitro test suggests that the agglomeration and sedimentation of alumina NPs affected cellular viability depending on cell types such as monocytes (THP-1), macrophages (J774A.1), lung carcinoma cells (A549), and embryonic kidney cells (293).     

A study on radial directional natural frequency and damping ratio in a vehicle tire

The measurement of radial directional natural frequency and damping ratio in a vehicle tire has been studied. Natural frequencies and damping ratios in the radial direction of various tires, from passenger car tires to truck bus tires, are reported. The radial direction modal parameters of tires subjected to different levels of inflation pressure, have been determined by using a frequency response function method. To obtain the theoretical natural frequency and mode shape, the plane vibration of a tire has been modeled as though it were that of a circular beam. By using the Tielking method that is based on Hamilton’s principle, theoretical results have been determined by considering the rotational velocity, tangential and radial stiffness, radial directional velocity and tension force which is due to tire inflation pressure. The results show that experimental conditions can be considered as the parameters that shift the natural frequency and damping ratio.     

Interaction of H2S with α-Fe2O3(0 0 0 1) surface

The atomic-scale structural changes in an α-Fe₂O₃ (hematite) (0 0 0 1) surface induced by sulfidation and subsequent oxidation processes were studied by X-ray photoemission spectroscopy, LEED, and X-ray standing wave (XSW) measurements. Annealing the α-Fe₂O₃(0 0 0 1) with a H₂S partial pressure of 1 × 10⁻⁷ Torr produced iron sulfides on the surface as the sulfur atoms reacted with the substrate Fe ions. The oxidation state of the substrate Fe changed from 3+ to 2+ as a result of the sulfidation. The XSW measured distance of the sulfur atomic-layer from the unrelaxed substrate oxygen layer was 3.16 Å. The sulfide phase consisted of three surface domains identified by LEED. Formation of the two-dimensional FeS₂ phase with structural parameters consistent with an outermost layer of (1 1 1) pyrite has been proposed. Atomic oxygen exposure oxidized the surface sulfide to a sulfate () and regenerated the α-Fe₂O₃(0 0 0 1) substrate, which was indicated by a (1 × 1) LEED pattern and the re-oxidization of Fe to 3+.