Conformal invariance and conserved quantities of Birkhoff systems under second-class Mei symmetry

This paper proposes a new concept of the conformal invariance and the conserved quantities for Birkhoff systems under second-class Mei symmetry.The definition about conformal invariance of Birkhoff systems under second-class Mei symmetry is given.The conformal factor in the determining equations is found.The relationship between Birkhoff system’s conformal invariance and second-class Mei symmetry are discussed.The necessary and sufficient conditions of conformal invariance,which are simultaneously of second-class symmetry,are given.And Birkhoff system’s conformal invariance may lead to corresponding Mei conserved quantities,which is deduced directly from the second-class Mei symmetry when the conformal invariance satisfies some conditions.Lastly,an example is provided to illustrate the application of the result.     

Mode decoupling in solid state ring laser based on stimulated Raman effect in polar crystals

In this paper we study the gain saturation induced mode-coupling control in solid state ring laser devices based on the stimulated Raman effect of the polar crystals in order to realize solid state ring laser gyroscopes.We theoretically investigate the mode coupling induced by gain saturation between clockwise (CW) and counterclockwise (CCW) propagating laser modes.Because the CW and CCW running waves are pumped with counter-propagating lasers respectively,the independent coexistence can be ensured.     

Charge dynamics and optical properties of layered cobaltates

We study the charge dynamics and electronic structure by optical spectroscopy technique. Here we focus on the following four issues: (1) the evolution of optical spectra with Na content; (2) the spectral features specific to different regions in the phase diagram; (3) the c-axis optical response for crystal at the A-type antiferromagnetic region; (4) the optical response of misfit-layered Bi₂M₂Co₂O_y (M=Ba, Sr, Ca) and Ca₃Co₄O_y single crystals.     

Phase dependent photoluminescence and energy transfer in Ca2P2O7: Eu2+, Mn2+ phosphors for white LEDs

α- and β-Ca₂P₂O₇: Eu²⁺, Mn²⁺ phosphors were prepared by solid-state reaction. Phase transition from tetragonal (β-phase) to monoclinic (α-phase) is performed. A strong orange emission of Mn²⁺ is observed in both α-and β-Ca₂P₂O₇: Eu²⁺, Mn²⁺ upon near ultraviolet (UV) excitation through energy transfer from Eu²⁺ to Mn²⁺. The transfer efficiencies for various Mn²⁺ concentrations are estimated based on lifetime measurements of the fluorescence of Eu²⁺ in the two phases. The photoluminescence excitation spectra of α-Ca₂P₂O₇: Eu²⁺, Mn²⁺ can cover 400 nm of the near-UV range, denoting its potential use as a phosphor with intense orange component for white light emitting diodes (LEDs).     

A strain-induced birefringent double-clad fiber Bragg grating

A strain-induced birefringence double-clad (DC) fiber Bragg grating (FBG) is proposed and demonstrated.The grating is fabricated in the core of rectangular inner cladding double clad fiber by using phase mask method. By applying lateral strain on the grating, the birefringence is induced. In order to detect the birefringent effect of the grating, we use it as the output mirror of a laser. When lateral strain is applied,the grating becomes birefringent. Therefore, one reflection peak of double-clad fiber Bragg grating becomes two peaks and the laser also lases in two wavelengths. The wavelength spacing of the laser can be tuned from 0 to 0.8 nm. The absolute wavelengths for the two polarizations can be tuned 1.2 and 2.0 nm,respectively.     

Surface-enhanced resonant Raman spectroscopy (SERRS) of single-walled carbon nanotubes absorbed on the Ag-coated anodic aluminum oxide (AAO) surface

In this paper, we developed a new kind of substrate, the silver-coated anodic aluminum oxide (AAO), to investigate the characters of surface-enhanced resonant Raman scattering (SERRS) of the dilute single-walled carbon nanotubes. Homogeneous Ag-coated AAO substrate was obtained by decomposing the AgNO₃ on the surface of AAO. single-walled carbon nanotubes (SWNTs) were directly grown onto this substrate through floating catalyst chemical vapor deposition method (CVD). SERRS of SWNTs was carried out using several different wavelength lasers. The bands coming from metallic SWNTs were significantly enhanced. The two SERRS mechanisms, the “electromagnetic” and “chemical” mechanism, were mainly responsible for the experiment results.     

松材线虫自然侵染后松树不同感病阶段针叶光谱特征变化

采用ASD野外光谱仪测量了黑松和马尾松在松材线虫自然侵染后不同感病阶段的反射光谱,分析了其中光谱特征参数及叶绿素变化情况.研究表明:(1)中红外波段反射光谱曲线对松树发病初期有一定的指示作用;(2)红边位置、绿峰高度、红谷反射率、红边斜率、水分胁迫波段反射率等参数的动态变化趋势与松材线虫侵染后两种松树的病害特征是一致的;(3)随病害程度加深两种松树叶绿素含量逐渐降低,且与光谱特征参数之间存显著线性关系.研究结果为利用高光谱遥感技术进行松材线虫病监测与预警提供参考,同时为针对不同发病阶段采用不同的措施治理松材线虫病提供新的实验依据.     

复合材料光弹性分析的近似方法

本文提出了一种用于光弹性复合材料的简化应变——光学定律。按照这一简化定律。模型材料的主应变差和主应变方向只要利用光弹性实验测出的等差线与等倾线即可求得。些是一种正交异性光弹性分析的近似方法,这一方法所得结果与实验数据比较,最大误差在10％左右。由于采用简化应变——光学定律使得正交异性光弹性分析工作大为简便,因此它是一种适合于工程应用的近似方法。     

谷氨酸钠对大鼠胃粘膜细胞的保护作用

本文报道了谷氨酸钠对0.6N HCl所致的粘胃膜损伤的影响.0.6N HCl给饥饿大鼠灌胃,可引起严重的胃粘膜损伤,但提前15min以0.25g/kg和0.5g/kg谷氨酸钠溶液灌胃,再给予0.6NHCl,均可防止由盐酸所致的胃粘膜损伤。消炎痛提前60min皮下注射,可阻断谷氨酸钠的细胞保护作用,此外谷氨酸钠     

抗坏血酸钛对鱼类、贝类及无尾两栖类的毒性研究

抗坏血酸钛对鲢鱼、草鱼、金鱼及泥鳅的毒性都很低,其96h TLm值为1736～10930mg/l。（敏感性顺序:鲢鱼>草鱼>金鱼>泥鳅）抗坏血酸钛对湖螺的48h TLm值与对蟾蜍蝌蚪的96hTLm值分别为12847.2与1886.5mg/l。经皮下注射,抗坏血酸钛对中华大蟾蜍的LD50为2.87g/kg。微核试验表明,钛试