Nuclear matrix of the most primitive eukaryote Archezoa

Accumulating evidence suggests that unicellular Archezoa are the most primitive eukaryotes and their nuclei are of significance to the study of evolution of the eukaryotic nucleus. Nuclear matrix is an ubiquitous important structure of eukaryotic nucleus; its evolution is certainly one of the most important parts of the evolution of nucleus. To study the evolution of nuclear matrix, nuclear matrices of Archezoa are investigated. Giardia lamblia cells are extracted sequentially. Both embedment-free section EM and whole mount cell EM of the extracted cells show that, like higher eukaryotes, this species has a residual nuclear matrix in its nucleus and rich intermediate filaments in its cytoplasm, and the two networks connect with each other to form a united network. But its nuclear matrix does not have nucleolar matrix and its lamina is not as typical as that of higher eukaryotes; Western blotting shows that lamina of Giardia and two other Archezoa Entamoeba invadens and Trichomonas vaginali all contain only one polypeptide each which reacts with a mammalia anti-lamin polyclonal serum and is similar to lamin B (67 ku) of mammlia in molecular weight. According to the results and references, it is suggested that nuclear matrix is an early acquisition of the eukaryotic nucleus, and it and the "eukaryotic chromatin" as a whole must have originated very early in the process of evolution of eukaryotic cell, and their origin should be an important prerequisite of the origin of eukaryotic nucleus; in the iamin (gene) family, B-type lamins (gene) should be the ancestral type and that A-type lamins (gene) might derive therefrom.

促性腺激素诱导猕猴排卵周期中卵巢纤溶酶原激活因子与抑制因子的变化

由促性腺激素诱导出的猕猴卵巢tPA(纤蛋白溶酶原激活因子)活性的增加与 排卵密切相关, 排卵前达到高峰, 排卵后明显下降; uPA只在排卵后的颗粒细胞 大量出现; PA的抑制因子PAI-1分泌高峰比tPA峰值早出现12-24h; 排卵来临时, tPA的明显上升导致PAI-1的空然下降。 结果说明: 卵巢中tPA和PAI-1活性的这 种平衡性的变化可能在排卵机制和维持卵巢的正常生理功能中起重要作用, 而uPA 或许与黄体形成的调节有某些关系。图4参17

马来眼子菜化感作用对斜生栅藻同工酶的影响

采用聚丙烯酰胺凝胶电泳的方法,研究了马来眼子菜(Potamogeton malaianus)和斜生栅藻(Scenedesmusobliquus)共培养系统中斜生栅藻的过氧化物酶(POD)、超歧化物氧化酶(SOD)、过氧化氢酶(CAT)、细胞色素氧化酶(COD)等同工酶的变化,探讨了沉水植物化感作用对藻类部分酶类的影响。与正常生长状态的对照组相比,马来眼子菜作用下的样品组斜生栅藻POD酶带总数保持稳定,但酶谱组成发生变化;样品组斜生栅藻SOD酶带数量减少而CAT酶带数量增加。综合结果表明,样品组藻体在化感作

摄食水平对异育银鲫生长及能量收支的影响

于 1 995年 6月在中国科学院水生生物研究所关桥繁殖场采集异育银鲫自繁鱼种(体重为 1 .2 6± 0 .0 5g) ,采用生长实验的方法 ,在 30℃水温下 ,测定其从饥饿到饱食 6个摄食水平下的生长和能量收支。结果表明 ,随着摄食水平的增加 ,鱼体干物质和能量含量、表观消化率呈上升趋势 ;湿重特定生长率随摄食水平的增加呈线性上升 ,干重和能量特定生长率呈对数增加 ;饲料转化效率随摄食水平增加而增加 ,达到最大值后维持不变。排泄能和总代谢耗能占摄入食物能的比例不受摄食水平的影响。最大摄食水平下的能量

Mode quality factor based on far-field emission for square resonators

The quality factors of modes in square resonators are calculated based on the far-field emission of the analytical field distribution. The obtained quality factors are in reasonable agreement with those calculated by the finite-difference time-domain (FDTD) technique and Pade approximation method. The emission power in the square diagonal directions for whispering-gallery-like modes in square resonators is zero due to the interference cancellation caused by the odd field distributions relative to the diagonal mirror planes, so they have larger quality factors than the modes with even field distribution.

Low threshold current density 1.5 mu m strained-MQW laser by n-type modulation-doping

1.5 mu m. n-type modulation-doping InGaAsP/InGaAsP strained multiple quantum wells grown by low pressure metalorganic chemistry vapor decomposition technology is reported for the first time in the world. N-type modulation-doped lasers exhibit much lower threshold current densities than conventional lasers with undoped barrier layers. The lowest threshold current density we obtained was 1052.5 A/cm(2) for 1000 mu m long lasers with seven quantum wells. The estimated threshold current density for an infinite cavity length was 94.72A/cm(2)/well, reduced by 23.3% compared with undoped barrier lasers. The n-type modulation doping effects on the lasing characteristics in 1.5 mu m devices have been demonstrated.

Silica and alumina thin films grown by liquid phase deposition

This work demonstrates the condition optimization during liquid phase deposition (LPD) Of SiO2/GaAs films. LPD method is further applied to form Al2O3 films on semiconductors with poison-free materials. Proceeding at room temperature with inexpensive equipment, LPD of silica and alumina films is potentially serviceable in microelectronics and related spheres.

Interface-related in-plane optical anisotropy of quantum wells studied by reflectance-difference spectroscopy

The in-plane optical anisotropy of three groups of GaAs/AlGaAs quantum well structures has been studied by reflectance-difference spectroscopy (RDS). For GaAs/Al0.36Ga0.64As single QW structures, it is found that the optical anisotropy increases quickly as the well width is decreased. For an Al0.02Ga0.98As/AlAs multiple QW with a well width of 20nm, the optical anisotropy is observed not only for the transitions between ground states but also for those between the excited states with transition index n up to 5. An increase of the anisotropy with the transition energy, or equivalently the transition index n, is clearly observed. The detailed analysis shows that the observed anisotropy arises from the interface asymmetry of QWs, which is introduced by atomic segregation or anisotropic interface roughness formed during the growth of the structures. More, when the 1 ML InAs is inserted at one interface of GaAs/AlGaAs QW, the optical anisotropy of the QW can be increased by a factor of 8 due to the enhanced asymmetry of the QW. These results demonstrate clearly that the RDS is a sensitive and powerful tool for the characterization of semiconductor interfaces.

Controlled growth of III-V compound semiconductor nano-structures and their application in quantum-devices

This paper reviews our work on controlled growth of self-assembled semiconductor nanostructures, and their application in light-emission devices. High-power, long-life quantum dots (QD) lasers emitting at similar to 1 mu m, red-emitting QD lasers, and long-wavelength QD lasers on GaAs substrates have successfully been achieved by optimizing the growth conditions of QDs.

The structural and photoluminescence character of InAs quantum dots grown on a combined InAlAs and GaAs strained buffer

The structural and photoluminescence (PL) properties of the InAs quantum dots (QDs) grown on a combined InAlAs and GaAs strained buffer layer have been investigated by AFM and PL measurements. The dependence of the critical thickness for the transition from 2D to 3D on the thickness of GaAs layer is demonstrated directly by RHEED. The effects of the introduced-InAlAs layer on the density and the aspect ratio of QDs have been discussed.

Structural and optical investigation of Mn-doped ZnS nanocrystals

Using a solution-based chemical method, we have prepared ZnS nanocrystals doped with high concentration of Mn2+. The X-ray diffraction analysis confirmed a zinc blende structure. The average size was about 3 nm. Photoluminescence spectrum showed room temperature emission in the visible spectrum, which consisted of the defect-related emission and the T-4(1)-(6)A(1) emission of Mn2+ ions. Compared with the undoped sample, the luminescence of the ZnS:Mn sample is enhanced by more than an order of magnitude, which indicated that the Mn2+ ions can efficiently boost the luminescence of ZnS nanocrystals.

Polarized photoluminescence and temperature-dependent - Photoluminescence study of InAs quantum wires on InP(001)

InAs quantum wires (QWRs) have been fabricated on the InP(001), which has been evidenced by TEM and polarized photoluminescence measurements (PPL). The monlayer-splitting peaks (MSPs) in the PL spectrum of InAs QWRs can be clearly observed at low temperature measurements. Supposing a peak-shift of MSP identical to that of bulk material, we obtain the thermal activation energies of up to 5 MSPs. The smaller thermal activation energies for the MSPs of higher energy lead to the fast red-shift of PL peak as a whole.

Raman scattering and photoluminescence studies of Zn1-xMnxO nanowires via vapor phase growth

In this paper, we investigated the Raman scattering and photoluminescence of Zn1-xMnxO nanowires synthesized by the vapor phase growth. The changes of E-2(High) and A(1(LO)) phonon frequency in Raman spectra indicate that the tensile stress increases while the free carrier concentration decreases with the increase of manganese. The Raman spectra exited by the different lasers exhibit the quantum confinement effect of Zn1-xMnxO nanowires. The photoluminescence spectra reveal that the near band emission is affected by the content of manganese obviously. The values Of I-UV/G decrease distinctly with the manganese increase also demonstrate that more stress introduced with the more substitution of Mn for Zn.