雨生红球藻诱变育种及突变株的筛选

虾青素是良好的着色剂，具有超强的抗氧化、捕获自由基、抗癌变，抗紫外线辐射、增强免疫等功能，在医疗、水产、食品和化妆品等生产领域有着广泛的市场。雨生红球藻（Haematococcus pluvialis）是一种单细胞的绿藻，在逆境条件下可积累高达4%干重的虾青素，是目前已知的天然虾青素含量最高的生物资源，规模化培养雨生红球藻是获取天然虾青素的最佳途径。 目前实验室研究和规模化培养使用的藻株多为出发株，存在一些缺陷：养殖过程中易被其它微藻、变形虫、原生动物、细菌等污染；只适合低温培养，28℃以上生长受抑制；生长相对较慢，培养周期长；尽管雨生红球藻是已知的天然虾青素含量最高的生物资源，但其含量仍然需要提高以适合规模化生产。因此筛选出温度适应范围广、生长速率快、虾青素含量高的雨生红球藻株一直是努力的方向。 本研究选用化学诱变剂甲基磺酸乙酯（EMS）和叠氮钠(NaN3)以及物理诱变剂紫外线（UV)分别处理雨生红球藻，测定各种诱变剂的致死率，及对红球藻生长和虾青素积累的影响，根据实验结果确定合适的诱变剂量和诱变时间，通过初筛、复筛、再次诱变等分离、筛选出生长速度快、虾青素含量高的单一藻株并进一步利用高压液相色谱等方法进行鉴定。 实验结果表明：浓度为0.2％-1.0％EMS处理4h，雨生红球藻H2的死亡率7%-35%；紫外线照射2min-10min，雨生红球藻H0的死亡率10%-98％；叠氮钠30mg/L－270 mg/L处理24h，雨生红球藻H0的死亡率为20％-100％。各种诱变剂诱变结束后立即观察发现死亡细胞的形态相似但存活细胞相态有所不同，死亡细胞呈浅绿色，轮廓模糊，形状不规则，质壁间隙消失，胞内有白色空泡；EMS处理后存活细胞，呈圆球状，部分失去鞭毛和前端突起，游动缓慢，处理后第二天，细胞即恢复游动和分裂，分裂方式与正常细胞相似。紫外线和叠氮钠处理后存活细胞壁加厚，呈深绿色，圆球状，部分失去鞭毛和突起，严重抑制细胞的游动和分裂，出现不动细胞，培养一段时间后才出现分裂细胞，游动的和不动的存活细胞主要是采用不对称无性繁殖，这与正常细胞的不对称无性繁殖有所不同，正常细胞中不对称无性繁殖的母细胞多为不动细胞。紫外线和叠氮钠处理后部分细胞还产生大量的小孢子（配子？），直径较小1-4m���在母细胞内不停摆动，四、五天后逐渐脱离母细胞。这和以前描述的有性繁殖很相似，但由于没观察到后期孢子配对过程和缺乏小孢子的DNA含量和倍性的有关数据，不能确定观察到的小孢子现象为雨生红球藻的有性繁殖。 各种诱变剂处理后，各组存活藻株的生长和虾青素积累情况同对照组相比发生了变化：EMS实验中0.4％EMS组生长速率提高24％，其它组的细胞生长速率有所降低。各组单细胞虾青素含量和积累速率均高于对照组，其中0.4％和0.8％处理组单细胞内虾青素含量分别提高了76％和90％，积累速率分别提高了69％和115％；紫外线实验中4min、6min和10min组生长速率分别提高20％、17％和35%，各组藻细胞虾青素积累速率有不同程度的提高，其中2min组和10min组虾青素积累速率提高幅度最大分别为32%和31%，单细胞内虾青素含量除10min处理组提高48%，其它各组均有不同幅度的降低；叠氮钠实验中60mg/L、120mg/L和180mg/L组细胞生长速率分别提高了13％、20％和9％，各组藻细胞内虾青素含量和虾青素积累速率得到明显的提高。其中60 mg/L和180 mg/L组单细胞内虾青素含量提高幅度最大，分别提高75%和140%。180mg/L和240mg/L组虾青素积累速率提高幅度最大，分别为280％和250％。 诱变后通过固体平板分离，得到一系列单一藻株，其中0.4%浓度EMS处理雨生红球藻H2 4h后分离到H2-419在生物量上比H2高出20％,但虾青素含量提高幅度不大。用UV对突变株H2-419再次诱变得到较稳定的藻株H2-419-4，培养五个月后与H2相比生物总量提高68%，单细胞内虾青素含量提高28％，经高压液相色谱分析证明H2-419-4类胡萝卜素提取物中主要成分仍然为虾青素，和出发株H2相比色素成分没有发生变化，只是各成分比例有所不同。 还分析研究了其它单一藻株，但或是稳定性较差，或虾青素含量高而生长慢。如雨生红球藻H2经0.02％EMS诱变十天，分离得到的E-L-22和出发株相比虾青素产量提高40％，但生物总量上降低了27％；5min紫外线照射雨生红球藻H0后，分离得到的UV-5-16和UV-5-14在生物总量分别提高7％和36％。叠氮钠200mg/L处理24h分离得到的藻株N-2-42生物总量提高43％，但藻株N-2-43生物总量比出发株降低8％。

Strain H-2-419-4 of Haematococcus pluvialis induced by ethyl methanesulphonate and ultraviolet radiation

Two strains H-2-410 and H-2-419 were obtained from the chemically mutated survivors of wild Haematococcus pluvialis 2 by using ethyl methanesulphonate (EMS). Strains H2-410 and H2-419 showed a fast cell growth with 13% and 20% increase in biomass compared to wild type, respectively. Then H-2-419-4, a fast cell growth and high astaxanthin accumulation strain, was obtained by exposing the strain H2-419 to ultraviolet radiation (UV) further. The total biomass, the astaxanthin content per cell, astaxanthin production of H-2-4194 showed 68%, 28%, and 120% increase compared to wild H. pluvialis 2, respectively. HPLC (High Performance Liquid Chromatography) data showed also an obvious proportional variation of different carotenoid compositions in the extracts of H2-4194 and the wild type, although no peak of carotenoids appeared or disappeared. Therefore, the main compositions in strain H-2-419-4, like its wild one, were free of astaxanthin, monoester, and diester of astaxanthin. The asexual reproduction in survivors after exposed to UV was not synchronous, and different from the normal synchronous asexual reproduction as the mother cells were motile instead of non-motile. Interestingly, some survivors from UV irradiation produced many mini-spores (or gamete?), the spores moved away from the mother cell gradually 4 or 5 days later. This is quite similar to sexual reproduction described by Elliot in 1934. However, whether this was sexual reproduction remains questionable, as no mating process has been observed.

Structural Evolution and Property Changes in Nd_{60}Al_{10}Fe_{20}Co_{10} Bulk Metallic Glass During Crystallization

The structural evolution and property changes in Nd60Al10Fe20Co10 bulk metallic glass (BMG) upon crystallization are investigated by the ultrasonic method, x-ray diffraction, density measurement, and differential scanning calorimetry. The elastic constants and Debye temperature of the BMG are obtained as a function of annealing temperature. Anomalous changes in ultrasonic velocities, elastic constants, and density are observed between 600–750 K, corresponding to the formation of metastable phases as an intermediate product in the crystallization process. The changes in acoustic velocities, elastic constants, density, and Debye temperature of the BMG relative to its fully crystallized state are much smaller, compared with those of other known BMGs, the differences being attributed to the microstructural feature of the BMG.

Nd_(60)Al_(10)Fe_(20)Co_(10)金属玻璃的变形行为

利用材料测试系统(MTS)、X-Ray 衍射(XRD)和扫描电镜(SEM)等手段研究了Nd 基大块金属玻璃的变形行为和断裂特征。Nd 基大块金属玻璃样品在室温下是脆性断裂,大约在500 K 时变形模式从非均匀变形转变为均匀变形,在523 K 以上表现出显著的塑性变形。在5×10-4 m/s 的应变速率下,这种Nd 基大块金属玻璃材料在523 K~600 K 之间出现明显的屈服应力下降现象,随后进入1 种稳定的粘性流动状态,而且这种屈服下降现象与温度和应变速率有关。这种在过冷液相区的变形行为与其他大块金属玻璃变形特征相似。合金的这种塑性变形行为表明了其存在稳定的过冷液相区,同时对其变形行为的研究有助于进一步了解Nd 基大块金属玻璃的反常热稳定性。

20～21世纪的力学

<正> 一、力学发展的趋势 1.20世纪力学的巨大成就 本世纪初边界层理论的提出,对力学的发展起了划时代的作用。从此,流体力学能够成功地解释流动对物体的阻力与升力,为航空、航天的发展奠定了科学基础。这个典型也影响与推动了其他力学分支的发展,使力学研究的内涵有了空前的充实、扩大与深化。早在20年代初便形成了活跃于整个20世纪内容广泛的应用力学,成为工程与应用科学的支柱。人们把空气动力学的研究看作是本世纪以科学为基础将航

加卸载响应比20年及其展望

地震孕育过程是一个非线性、不可逆的过程,震源区介质的加载响应不同于卸载响应,这种加载响应与卸载响应的差别可以定量地刻画地震的孕育过程。基于这个物理概念,提出了一个新的参数加卸载响应比,作为一类地震前兆,用来定量预测强震的发生。在本文中,首先简单回顾了加卸载响应比的发展历史,然后详细介绍了地震震例检验、数值计算、实验研究、地震预测精度、可信度等方面的内容,最后对加卸载响应比的前景进行了展望。

当代的力学热点——由介绍第20届国际理论和应用力学大会引起的思考

本文通过介绍第２０ 届国际理论和应用力学大会的概况，分析了当代力学发展的现状和热点，并由此提出了对我国力学发展的思考和构想。

微重力落管法制备Nd_(60)Al_(10)Fe_(20)Co_(10)非晶薄片的磁性能研究

采用微重力落管法制得了Nd6 0 Al1 0 Fe2 0 Co1 0 非晶薄片 .利用X衍射 (XRD)分析了Nd6 0 Al1 0 Fe2 0 Co1 0 非晶薄片的结构特征 .用振动样品磁强计 (VSM)研究了其磁性能 .结果表明微重力落管法制得的非晶薄片具有硬磁性 ,与快速非平衡凝固(如甩带法 )试样的XRD相比 ,尽管其曲线还是较为典型的非晶相漫散衍射峰 ,但已有少量的不规则的类似晶化的突起小峰 ,表明该非晶片中已经有微量晶态合金或者细小晶粒析出 ,初步分析可能是生成了类似于亚稳A1 相的短程有序原子团簇或者是较大尺寸的纳米晶 ,这种短程有序原子团簇或纳米晶是Nd6 0 Al1 0 Fe2 0 Co1 0 非晶薄片显示硬磁性的主要原因

Nd_(60)Al_(10)Fe_(20)Co_(10)大块金属玻璃的玻璃转变和晶化过程

本文利用DSC、X射线衍射和动态力学分析以及扫描电子显微镜研究了Nd_(60)Al_(10)Fe_(20)Co_(10)大块金属玻璃(BMG)的玻璃转变和晶化过程。结果表明,合金的动态力学分析结果清楚地反映出材料的玻璃转变和晶化过程。由此确定材料的玻璃转变温度为493K,初始晶化温度为590K。X射线衍射和组织分析表明合金的晶化过程为:非晶α→非晶α’+未知亚稳NdFeAl相→非晶α’+初晶δ相→初晶δ相+共晶δ相+Nd_3Co+Nd_3Al。

High-energy ion emission from cooled deuterium clusters in 20 TW laser fields

High-energy ion emission from intense-ultrashort (30fs) laser-pulse- cooled deuterium-cluster (80K) interaction is measured. The deuterium ions have an average energy 20keV, which greatly exceeds Zweiback's expectation [Phys. Rev. Lett. 84 (2000) 2634]. These fast deuterium ions can be used to drive fusion and have a broad prospect.

Femtosecond optical Kerr effect study of Ge(10)AS(40)S(30)Se(20) film

The results of the femtosecond optical heterodyne detection of optical Kerr effect at 805 nm with the 80 fs ultrafast pulses in amorphous Ge10As40S30Se20 film is reported in this paper. The film shows an optical non-linear response of: 200 fs under ultrafast 80 fs-pulse excitation and the values of real and imaginary parts of non-linear susceptibility chi((3)) were 9.0 X 10(-12) and -4.0 X 10(-12) esu, respectively. The large third-order non-linearity and ultrafast response are attributed to the ultrafast distortion of the electron orbits surrounding the average positions of the nucleus of Ge, As, S and Se atoms. This Ge10As40S30Se20 chalcogenide glass would be expected as a promising material for optical switching technique. (c) 2005 Elsevier Ltd. All rights reserved.

Preparation, characterization and gas sensing properties of lead tetra-(tert-butyl)-5,10,1 5,20-tetraazaporphyrin spin-coating films

A spin-coated film of lead tetra-(tert-butyl)-5,10,15,20-tetraazaporphyrin complex (PbTAP(t-Bu)(4)) was obtained and characterized by IR spectra, absorption spectra and atomic force microscopy. The response and recovery characteristics of the film to NH3, NO2 and C2H5OH vapor were investigated at room temperature. In addition, the reversibility and stability of the film to NH3 were also studied. The results indicate that the PbTAP(t-Bu)(4) derivative can be exploited as an NH3 sensor at room temperature. (c) 2007 Elsevier B.V. All rights reserved.

20-W average power, high repetition rate, nanosecond pulse with diffraction limit from an all-fiber MOPA system

In this article, we report an all-fiber master oscillator power amplifier (MOPA) system, which can provide high repetition rate and nanosecond pulse with diffraction-limit. The system was constructed using a (2 + 1) X 1 multimode combiner. The Q-Switched, LD pumped Nd:YVO4 solid-state laser wets used (is master oscillator. The 976-nm fiber-coupled module is used as pump source. A 10-m long China-made Yb3+-doped D-shape double-clad large-mode-area fiber was used as amplifier fiber. The MOPA produced as much as 20-W average power with nanosecond pulse and near diffraction limited. The pulse duration is maintained at about 15 its during 50-175 kHz. The system employs a simple and compact architecture and is therefore suitable for the use in practical applications such as scientific and military airborne LIDAR and imaging. Based oil this system. the amplification performances of. the all fiber amplifier is investigated. (C) 2008 Wiley Periodicals, Inc.