Y2O3 stabilized ZrO2 thin films deposited by electron beam evaporation: Structural, morphological characterization and laser induced damage threshold

Four kinds of Y2O3 stabilized ZrO2 (YSZ) thin films with different Y2O3 content have been prepared on BK7 substrates by electron-beam evaporation method. Structural properties and surface morphology of thin films were investigated by X-ray diffraction (XRD) spectra and scanning probe microscope. Laser induced damage threshold (LIDT) was determined. It was found that crystalline phase and microstructure of YSZ thin films was dependent on Y2O3 molar content. YSZ thin films changed from monoclinic phase to high temperature phase (tetragonal and cubic) with the increase of Y2O3 content. The LIDT of stabilized thin film is more than that of unstabilized thin films. The reason is that ZrO2 material undergoes phase transition during the course of e-beam evaporation resulting in more numbers of defects compared to that of YSZ thin films. These defects act as absorptive center and the original breakdown points. (c) 2006 Elsevier B.V. All rights reserved.

Laser-induced damage of Ti O2 Si O2 high reflector at 1064 nm

A high laser-induced damage threshold (LIDT) TiO2/SiO2 high reflector (HR) at 1064 nm is deposited by e-beam evaporation. The HR is characterized by optical properties, surface, and cross section structure. LIDT is tested at 1064 nm with a 12 ns laser pulse in the one-on-one mode. Raman technique and scanning electron Microscope are used to analyze the laser-induced modification of HR. The possible damage mechanism is discussed. It is found that the LIDT of HR is influenced by the nanometer precursor in the surface, the intrinsic absorption of film material, the compactness of the cross section and surface structure, and the homogeneity of TiO2 layer. Three typical damage morphologies such as flat-bottom pit, delamination, and plasma scald determine well the nanometer defect initiation mechanism. The laser-induced crystallization consists well with the thermal damage nature of HR. (C) 2008 American Institute of Physics.

Influences of CO2 laser annealing on mechanical and laser-induced damage properties of ZrO2 thin films

Zirconium dioxide (ZrO2) thin films were deposited on BK7 glass substrates by the electron beam evaporation method. A continuous wave CO2 laser was used to anneal the ZrO2 thin films to investigate whether beneficial changes could be produced. After annealing at different laser scanning speeds by CO2 laser, weak absorption of the coatings was measured by the surface thermal lensing (STL) technique, and then laser-induced damage threshold (LIDT) was also determined. It was found that the weak absorption decreased first, while the laser scanning speed is below some value, then increased. The LIDT of the ZrO2 coatings decreased greatly when the laser scanning speeds were below some value. A Nomarski microscope was employed to map the damage morphology, and it was found that the damage behavior was defect-initiated both for annealed and as-deposited samples. The influences of post-deposition CO2 laser annealing on the structural and mechanical properties of the films have also been investigated by X-ray diffraction and ZYGO interferometer. It was found that the microstructure of the ZrO2 films did not change. The residual stress in ZrO2 films showed a tendency from tensile to compressive after CO, laser annealing, and the variation quantity of the residual stress increased with decreasing laser scanning speed. The residual stress may be mitigated to some extent at proper treatment parameters. (c) 2007 Elsevier GmbH. All rights reserved.

用共聚焦扫描显微镜检术和酶法分离技术观测观察水稻胚囊发育

本文中以水稻为实验材料，用共聚焦扫描显微镜检术(CLSM)和酶法分离技术观察其胚囊取得好的效果，主要实验结果如下： 1.水稻子房分别用FAA和4%戊二醛固定液固定，经乙醇脱水，然后用冬青油整体透明及丁香油封片。在共聚焦扫描显微镜下，发育中的水稻胚囊显示自发荧光，可分辨出胚囊内部结构。FAA和4%戊二醛两种固定液效果不同，后者效果更佳。用上述实验程序进一步观察拟南芥菜胚囊及水稻和拟南芥菜花粉表明，CLSM可用于快速观察分析水稻和拟南芥菜胚囊发育过程以及水稻胚囊败育情况，但不适用于观察分析其花粉发育过程。 2.水稻子房用FAA、FPA或卡诺氏固定液固定，经乙醇转至蒸镏水，然后置于由纤维素酶和果胶酶组成的酶液中，在37℃保温条件下进行连续振荡酶解，在振荡过程中辅以手工显微操作，由此即可分离出水稻固定胚珠的胚囊。用相差显微镜观察分离的胚囊表明，胚囊整体性及立体感强，观察效果好。在成功分离水稻固定材料胚囊的基础上，初步尝试了水稻新鲜材料胚囊的分离。

松杉类植物花粉发育和传粉生物学的研究

本文用光学显微镜结合荧光技术对青扦花粉的发育过程进行了观察;用共聚焦显微镜观察了白扦生长花粉管细胞内的游离Ca2+分布;利用原子力显微镜对雪松和水杉花粉外壁的亚结构进行了研究：用透射电镜、扫描电镜及解剖镜等技术研究了侧柏、北美香柏、红豆杉、粗榧和白皮松的传粉机制，结果如下。 青扦花粉的发育过程与松科其它一些植物花粉的发育模式相似。从小孢子母细胞到成熟花粉约二十天左右。小孢子母细胞进入减数分裂前彼此分开，但在某些部位仍有连接。细胞质内有大量淀粉粒，在减数分裂过程中减少或消失，没有观察到明显的淀粉粒带。减数分裂中的胞质分裂为同时型，四分体为四面体型。小孢子刚从四分体释放出来时，气囊已开始形成，细胞中含大量淀粉粒。随着小孢子的发育，其体积增大，并出现液泡，细胞核移向一侧。小孢子第一次不对称分裂产生一个大的中央细胞和一个小的原叶细胞。中央细胞不久就进行第二次分裂产生精子器原始细胞和第二原叶细胞。原叶细胞形成后，其与中央细胞或精子器原始细胞之间的壁逐渐沉积胼胝质，以后随着原叶细胞的退化，胼胝质壁消失。精子器原始细胞分裂形成管细胞和生殖细胞，生殖细胞在散粉前分裂形成体细胞（精原细胞）和柄细胞（不育细胞）。成熟花粉为5细胞，但两个原叶细胞已退化消失。 白扦花粉在10%蔗糖+0.01%硼酸的液体培养基内培养12小时后开始萌发。在正常生长的花粉管中，其顶端有一个透明区，而透明区后则含有大量的贮藏物质颗粒。在停止生长的花粉管中透明区消失，而整个花粉管顶端也被储藏物质颗粒充满。正常生长的花粉管顶端有一个较高的Ca2+浓度。在停止生长的花粉管内不具有这样一个Ca2+梯度。 雪松和水杉二种花粉外壁中由孢粉素构成的亚结构单位形态相似，均呈颗粒状，但大小略有不同。雪松的长56-99 nm，宽42-74;水杉的长81-118 nm，宽43-98 nm。在雪松中这些亚单位紧密排列组成短棒状或球状的花粉外壁结构单位，再由几个到十几个这样的结构单位组成较大的岛屿状结构。在这些岛屿状结构之间有大小不一的空隙存在，整个花粉外壁由这样一些岛屿状结构交互连接形成。水杉花粉外壁的亚单位排列也较紧密，且有3-10个成群分布的趋势，但各群之间界限不明显。此外，雪松和水杉的花粉外壁亚单位均无螺旋状排列趋势，这一结果倾向于支持Southworth关于花粉外壁亚单位颗粒状并呈网状排列的观点。 白皮松胚珠倒生，其发育过程与松属的其它种相似，成熟胚珠珠孔端具两手臂状结构，有利于接收花粉。花粉具气囊。传粉期间，没有观察到传粉滴产生，但珠心顶端细胞解体形成花粉室。花粉室内可接受一至几个花粉，花粉在花粉室内的位置无明方向性。传粉时，胚珠处于大孢子线细胞时期。花粉在花粉室内萌发形成花粉管进入珠心组织，花粉管在珠心内生长一段时间后停止生长，并于次年春天重新启动生长。离体生长的花粉管顶端常有胼胝质产生，但顶端区域后的花粉管壁上却无胼胝质沉积。 侧柏、北美香柏、红豆杉和粗榧均为直生胚珠。传粉时胚珠产生传粉滴。在红豆杉胚珠发育早期，珠心表面细胞轮廓清晰;而在后期，其珠心表面则形成了一层膜状结构。这层膜状结构在传粉前随珠心细胞的解体而破裂，珠心细胞的降解产物参与了传粉滴形成。在传粉前和传粉期，珠心细胞内含大量的线粒体、内质网、高尔基体和小泡。传粉滴主要由珠心细胞分泌形成。这四种植物的花粉均无气囊，属可湿性花粉。红豆杉和粗榧的花粉水合时，内壁膨胀，外壁开裂。通常情况下，红豆杉花粉的外壁保留在传粉滴的表面，而花粉的其它部分沉入传粉滴内。侧柏和北美香柏的传粉滴授粉后，花粉进入传粉滴导致传粉滴的明显收缩。在侧柏中传粉滴授粉后100分钟内就完全收缩进入珠孔。传粉滴收缩的速率与所授花粉数量和花粉的种类有关。与侧柏亲缘关系较近植物花粉引起传粉滴的收缩速率和侧柏自身花粉引起的传粉滴收缩速率相似;反之，收缩速率变慢。侧柏传粉滴的收缩可能主要是由于花粉减弱胚珠分泌的结果。但授粉不引起红豆杉和粗榧传粉滴的明显收缩。在红豆杉和粗榧中，从授粉到传粉完全收缩需要20-24小时。这两种植物传粉滴的收缩可能主要是蒸发引起的非代谢性过程，与侧柏和美香柏属于不同的传粉滴收缩机制。

Genome-wide SNP and haplotype analyses reveal a rich history underlying dog domestication

Advances in genome technology have facilitated a new understanding of the historical and genetic processes crucial to rapid phenotypic evolution under domestication(1,2). To understand the process of dog diversification better, we conducted an extensive genome-wide survey of more than 48,000 single nucleotide polymorphisms in dogs and their wild progenitor, the grey wolf. Here we show that dog breeds share a higher proportion of multi-locus haplotypes unique to grey wolves from the Middle East, indicating that they are a dominant source of genetic diversity for dogs rather than wolves from east Asia, as suggested by mitochondrial DNA sequence data(3). Furthermore, we find a surprising correspondence between genetic and phenotypic/functional breed groupings but there are exceptions that suggest phenotypic diversification depended in part on the repeated crossing of individuals with novel phenotypes. Our results show that Middle Eastern wolves were a critical source of genome diversity, although interbreeding with local wolf populations clearly occurred elsewhere in the early history of specific lineages. More recently, the evolution of modern dog breeds seems to have been an iterative process that drew on a limited genetic toolkit to create remarkable phenotypic diversity.

Relationship between trichosanthin cytotoxicity and its intracellular concentration

Trichosanthin (TCS) is a type I ribosome-inactivating protein with board spectrum of biological activity. Toxicity of this compound differs in different cell lines and this study examined the cause of such difference. It is generally believed that TCS toxicity is mediated through intracellular ribosome inactivation. Therefore, TCS toxicity should be determined by the amount inside cells rather than outside. Three different cell types IC21, JAR and Vero cell lines were chosen with high, medium and low sensitivity to TCS. Intracellular concentrations of fluorescein isothiocyanate labeled TCS were determined by laser scanning confocal microscopy. A good relationship was demonstrated between intracellular TCS concentration and toxicity. Highest intracellular concentration was found in IC21, followed by JAR, and lowest in Vero cells. When the intracellular TCS concentrations in these cells were reduced by using a competitive inhibitor to block cell entry, cytotoxicity was not observed. In conclusion, there is strong evidence to indicate that cytotoxicity of TCS is dependent on its intracellular concentration. Variation of cytotoxicity in different cells may be related to the mechanisms affecting its internalization. (C) 2002 Published by Elsevier Science Ireland Ltd.

口腔移植材料与成骨细胞相容性的激光共聚焦显微镜观察

下载PDF阅读器目的:观察不同处理的钛金属表面与成骨细胞的生物相容性.方法:利用共聚焦显微镜荧光信号通过物镜返回光电倍增管成像的原理,获取不透光的钛金属表面图像,对钛金属表面(打磨、喷砂、喷砂酸蚀表面)接种的成骨细胞骨架进行荧光标记,并用共聚焦显微镜获取荧光图像,观察细胞和钛金属表面的生物相容性,并且通过逐渐深入的多层扫描,探索细胞和移植材料结合的进一步信息.结果:喷砂表面适合成骨细胞的贴附和生长.结论: 钛金属与成骨细胞的结合情况主要与金属表面的物理形态有关.

Cell surface display of functionally active lipases from Yarrowia lipolytica in Pichia pastoris

The lipase genes of Yarrowia lipolytica, LIPY7 and LIPY8, fused with FLO-flocculation domain sequence from Saccharomyces cerevisiae at their N-termini, were expressed in Pichia pastoris KM71. Following the induction with methanol, the recombinant proteins were displayed on the cell surface of P. pastoris, as confirmed by the confocal laser scanning microscopy. The LipY7p and LipY8p were anchored on P. pastoris via the flocculation functional domain of Flo 1 p. The surface-displayed lipases were characterized for their application as the whole-cell biocatalyst. These lipases can also be cleaved off from their anchor by enterokinase treatment to yield functionally active proteins in the supernatant offering an alternative purification method for LipY7p and LipY8p. (c) 2007 Elsevier Inc. All rights reserved.

The effects of substrate temperature on the structure and properties of ZnO films prepared by pulsed laser deposition

ZnO thin films were prepared by pulsed laser deposition (PLD) on glass substrates with growth temperature from room temperature (RT) to 500 degrees C. The effects of substrate temperature on the structural and optical properties of ZnO films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission spectra, and RT photoluminescence (PL) measurements. The results showed that crystalline and (0 0 2)-oriented ZnO films were obtained at all substrate temperatures. As the substrate temperature increased from RT to 500 degrees C, the ratio of grain size in height direction to that in the lateral direction gradually decreased. The same grain size in two directions was obtained at 200 degrees C, and the size was smallest in all samples, which may result in maximum E, and E-0 of the films. UV emission was observed only in the films grown at 200 degrees C, which is probably because the stoichiometry of ZnO films was improved at a suitable substrate temperature. It was suggested that the UV emission might be related to the stoichiometry in the ZnO film rather than the grain size of the thin film. (c) 2007 Elsevier Ltd. All rights reserved.

Crystallization of amorphous Si films by pulsed laser annealing and their structural characteristics

Nanocrystalline silicon (nc-Si) films were prepared by pulsed laser annealed crystallization of amorphous silicon (alpha-Si) films on SiO2-coated quartz or glass substrates. The effect of laser energy density on structural characteristics of nc-Si films was investigated. The Ni-induced crystallization of the a-Si films was also discussed. The surface morphology and microstructure of these films were characterized by scanning electron microscopy, high-resolution electron microscopy, atomic force microscopy and Raman scattering spectroscopy. The results show that not only can the alpha-Si films be crystallized by the laser annealing technique, but also the size of Si nanocrystallites can be controlled by varying the laser energy density. Their average size is about 4-6 nm. We present a surface tension and interface strain model used for describing the laser annealed crystallization of the alpha-Si films. The doping of Ni atoms may effectively reduce the threshold value of laser energy density to crystallize the alpha-Si films, and the flocculent-like Si nanostructures could be formed by Ni-induced crystallization of the alpha-Si films.

Electron beam and laser testing on the novel stripixel detectors

The novel Si stripixel detector, developed at BNL (Brookhaven National Laboratory), has been applied in the development of a prototype Si strip detector system for the PHENIX Upgrade at RHIC. The Si stripixel detector can generate X-Y two-dimensional (2D) position sensitivity with single-sided processing and readout. Test stripixel detectors with pitches of 85 and 560 mu m have been subjected to the electron beam test in a SEM set-up, and to the laser beam test in a lab test fixture with an X-Y-Z table for laser scanning. Test results have shown that the X and Y strips are well isolated from each other, and 2D position sensitivity has been well demonstrated in the novel stripixel detectors. (c) 2005 Elsevier B.V. All rights reserved.

Structural and optical properties of ZnO thin films on glass substrate grown by laser-ablating Zn target in oxygen atmosphere

C-axis-orientated ZnO thin films were prepared on glass substrates by pulsed-laser deposition (PLD) technique in an oxygen-reactive atmosphere, using a metallic Zn target. The effects of growth condition such as laser energy and substrate temperature on the structural and optical properties of ZnO films had been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission spectra and room-temperature (RT) photoluminescence (PL) measurements. The results showed that the thickness, crystallite size, and compactness of ZnO films increased with the laser energy and substrate temperature. Both the absorption edges and the UV emission peaks of the films exhibited redshift, and UV emission intensity gradually increased as the laser energy and substrate temperature increased. From these results, it was concluded that crystalline quality of ZnO films was improved with increasing laser energy and substrate temperature. (c) 2007 Elsevier B.N. All rights reserved.

Detect the sub-wavelength data by applying a very-small-aperture laser

We present a theoretical and experimental research about applying a very-small-aperture laser (VSAL) to detect sub-wavelength data. Near-field distribution of a VSAL, which is essential for the application of such near-field devices, will be affected by the sample or fiber posited in the near-field region of the aperture. When the device is applied to detect the sub-wavelength data, the real resolution depends on the near-field spot size, the divergent angle of the beam and the distance from the aperture to the sample. Experimental results, including the near-field detection of the spot and detection of the sub-wavelength data by using the VSAL, are presented in this paper. We realize the two dimensional scanning about the sub-wavelength data (with the width 600 nm) by employing a VSAL with a 300 nm x 300 nm aperture.

Near-field scanning optical microscopy with an active probe

A near-field scanning optical microscopy (NSOM) system employing a very-small-aperture laser (VSAL) as an active probe is reported in this Letter. The VSAL in our experiment has an aperture size of 300 nmx300 nm and a near-field spot size of about 600 nm. The resolution of the NSOM system with the VSAL can reach about 600 nm, and even 400 nm. Considering the high output power of the VSAL, such a NSOM system is a potentially useful tool for nanodetection, data storage, nanolithography, and nanobiology.