Developments in transgenic fish in the people's Republic of China

In the People's Republic of China, genetically modified (GM) fish are being developed primarily to produce desirable alterations to growth rates or feed-conversion efficiency. Up to the present, no transgenic fish have been commercially approved for human consumption. This review introduces advances in the People's Republic of China in transgenic fish studies, biosafety studies of fast-growth GM fish, and the regulation of GM fish.

A new genus and species of freshwater monostiliferous hoplonemertean (Nemertea, Enopla) from the People's Republic of China

A new genus and species of freshwater monostiliferous hoplonemertean, Limnemertes poyangensis gen. et sp. nov., from Poyang Lake, People's Republic of China, is described and illustrated. The taxon is compared and contrasted with previously described freshwater hoplonemerteans. This is the fourth species of freshwater nemertean to be described from China and the first recorded from Poyang Lake.

Records of enchytraeidae (Clitellata) from the People's Republic of China

Eleven species of terrestrial and aquatic Enchytraeidae are reported from southeastern China. Fridericia multisegmentata and Enchytraeus athecatus are new to science, while most of the others are recorded from the country for the first time.

Interaction between the intrinsic second- and third-order optical fields in an Al0.53Ga0.47N/GaN heterostructure

We present an experimental demonstration of the interaction between the intrinsic second- and third-order optical fields in an Al0.53Ga0.47N/GaN heterostructure. The sample was deposited by metal-organic chemical vapor deposition on (0001) sapphire. The nonlinear optical coefficients of the sample, which were measured with a Mach-Zehnder interferometer system, quadratically increase with the applied modulating voltage, indicating the existence of the third-order optical field. The third-order signal was then detected by the Z-scan method and we calculated the built-in dc field on the AlGaN/GaN interface to confirm the strong interaction between the intrinsic second- and third-order optical fields. (c) 2008 American Institute of Physics.

Third-order optical nonlinearities of lead-free (Na1-xKx)(0.5)Bi0.5TiO3 thin films

(Na1-xKx)(0.5)Bi0.5TiO3 (NKBT) (x = 0.1, 0.2, and 0.3) thin films with good surface morphology and rhombohedral perovskite structure were fabricated on quartz substrates by a sol-gel process. The fundamental optical constants (the band gaps, linear refractive indices and absorption coefficients) of the films were obtained through optical transmittance measurements. The nonlinear optical properties were investigated by Z-scan technique performed at 532 nm with a picosecond laser. A two-photon absorption effect closely related with potassium-doping content was found in thin films, and the nonlinear refractive index n(2) increases evidently with potassium-doping. The real part of the third-order nonlinear susceptibility chi((3)) is much larger than its imaginary part, indicating that the third-order optical nonlinear response of the NKBT films is dominated by the optical nonlinear refractive behavior. These results show that NKBT thin films have potential applications in nonlinear optics. (C) 2007 Elsevier B.V. All rights reserved.

Observation of the third subband population in modulation-doped InGaAs/InAlAs heterostructure

The population of the third (n = 3) two-dimensional electron subband of InGaAs/InAlAs modulation-doped structures has been observed by means of Fourier transform photoluminescence (PL). Three well resolved PL peaks centred at 0.737, 0.908, and 0.980eV are observed, which are attributed to the transitions from the lowest three electron subbands to the n = 1 heavy-hole subband. The subband separations clearly exhibiting the features of the stepped quantum well with triangle and square potentials are consistent with numerical calculation. Thanks to the presence of Fermi cutoff, the population ratio of these three subbands can be estimated. Temperature- and excitation-dependent luminescences are also analyzed.

The third subband population in modulation-doped InGaAs/InAlAs heterostructures

We have observed the population of the third (n=3) two-dimensional electron subband of InGaAs/ InAlAs modulation-doped structures with very dense sheet carrier density by means of Fourier transform photoluminescence (PL). Three well-resolved PL peaks centered at 0.737, 0.908, and 0.980 eV are observed, which are attributed to the recombination transitions from the lowest three electron subbands to the n=1 heavy-hole subband. The subband separations clearly exhibit the features of the stepped quantum well with triangle and square potential, consistent with numerical calculation. Thanks to the presence of the Fermi cutoff, the population ratio of these three subbands can be estimated. Temperature and excitation intensity dependence of the quantum well luminescence intensity is also analyzed. (C) 1997 American Institute of Physics.

Phase mismatching analysis of third harmonic generation in BBO crystal

对BBO晶体三次谐波转换过程中相位失配情况进行了研究。当BBO 晶体按Ⅰ类相位匹配(oo→e)进行三次谐波转换时，如果保持基频光正入射，当倍频光从两个相互独立的平面方向(晶体主截面及主截面的垂面)偏离预期方向时，相位失配将出现变化，并且在两个面内的偏离量对转换效率的影响程度不同。我们分别数值模拟了两个方向上的相位失配情况，并给出了谐波转换效率同入射角度偏差的关系。数值模拟结果表明，在主截面内的相位匹配容限角为0.2°，在主截面垂面内的相位匹配容限角为4.5°。同时，开展了实验研究，实验结果与数值模拟结果高度吻合，表明在主截面内的角度偏差对转换效率的影响更大。