超重环境对斑马鱼仔鱼早期发育和耳石形态学与化学组成的影响

目的本研究以模式动物斑马鱼为研究对象,通过研究超重下鱼体的早期发育和耳石变化,探讨了脊椎动物前庭系统对超重环境的适应机制。方法斑马鱼受精卵在受精后10h分别置于1G和5G重力环境中,观察鱼体发育状态和耳石的形态;使用Zeiss软件比较1G和5G下耳石大小;使用EDAX检测耳石微化学成分含量变化。结果1)斑马鱼从鱼卵向早期仔鱼发育过程中超重环境影响仔鱼发育,耳石形态在初期显著变大(P<0.01),其后耳石变小;2)EDAX检测表明,耳石中S和Sr含量升高,Na和Ca的含量减少;3)出现矢耳石与微耳石融合的现

Failure mechanisms in brittle laminates

Steady-state tunneling and plane-strain delamination of an H-shape crack are examined for elastic, isotropic multi layers. Both tunneling and delamination are analysed by employing linear elastic fracture mechanics within a 2D finite element framework. Failure maps are produced to reveal the sensitivity of cracking path to the relative toughness of layer and interface, and to the stiffness mismatch of layers.

瓣结鱼食性的研究

以采自贵州境内清水江、都柳江的318尾瓣结鱼(Tor(Foliter)brevifilis brevifilis)为研究对象,从食物组成、摄食强度和摄食形态学等方面研究了瓣结鱼食性的特点。结果表明:瓣结鱼的食物由双翅目昆虫幼虫等17类饵料生物组成,并以双翅目昆虫幼虫的出现率最高。瓣结鱼的充塞度按春、夏、秋、冬季逐渐增高,季节性变化明显。充塞指数随体长生长显著减少,而摄食率则随体长生长逐渐增加。充塞指数和摄食率均以V期性腺个体为最低。瓣结鱼为底层杂食性鱼类。

滇池试验围隔内不同形态铁浓度的变化与物化因子的关系

在蓝藻水华形成以后,通过围隔实验,从2003年6月份到10月份定期采样测定水体中的pH、溶解氧(DO)、水温、总铁、亚铁、过滤性铁(<0.45μm)和可溶性磷的浓度,研究物化因子对不同形态铁浓度变化的影响。实验结果表明,蓝藻水华优势种微囊藻在pH 7—9和水温17.5—20.5℃的条件下,生长旺盛,消耗了大量的亚铁,使亚铁浓度大幅度下降;溶解氧和磷酸盐对亚铁浓度没有显著影响;在水华蓝藻严重发生的条件下,水体中的总铁和过滤性铁浓度没有显著意义的变化,而亚铁浓度的变化与水华蓝藻的种群密度成显著负相关(r=-0

Synthesis and luminescence properties of erbium silicate thin films

We have studied the structure and the room temperature luminescence of erbium silicate thin films deposited by rf magnetron sputtering. Films deposited on silicon oxide layers are characterized by good structural properties and excellent stability. The optical properties of these films are strongly improved by rapid thermal annealing processes performed in the range of temperature 800-1250 °C. In fact through the reduction of the defect density of the material, a very efficient room temperature photoluminescence at 1535 nm is obtained. We have also investigated the influence of the annealing ambient, by finding that treatments in O2 atmosphere are significantly more efficient in improving the optical properties of the material with respect to processes in N2. Upconversion effects become effective only when erbium silicate is excited with high pump powers. The evidence that all Er atoms (about 1022 cm-3) in erbium silicate films are optically active suggests interesting perspectives for optoelectronic applications of this material. © 2007 Elsevier B.V. All rights reserved.

围隔中鲢和菹草控藻效果及其生态学意义

在滇池沿岸的池塘中 ,构建了面积为 10 0m2 ,水深为 85cm ,底质均为淤泥的四个围隔 ,其中在三个围隔内分别放养密度为 10 0g/m3 、75g/m3 、5 0g/m3 的鲢。它们均在一定程度上控制浮游植物的生物量并改善水体透明度 ,其中初始放养鲢 75g/m3 的围隔控制效果最明显。放养三种密度的鲢在有效控制微囊藻水华的同时 ,原先水体的优势种类发生质的变化 ,水体中浮游植物的多样性也明显增加。放鱼 2个月后 ,在生物操纵的围隔中同时种入菹草 ,在75g/m3 的鲢控藻的围隔中 ,菹草长势良

湖泊放流二龄河蟹的食性

在保安湖一围栏区 ( 3.3hm2 )周年采样 ,共获得可供食性分析用的二龄河蟹 36 2只 (壳宽 1.99— 6 .2 4cm)。胃含物分析表明 ,河蟹为杂食性 ,兼具肉食性倾向 ,以底层群落为食 ,食谱极为复杂 ,包括水生大型植物、藻类 ( 47个属 )、原生动物、轮虫、节肢动物、环节动物、软体动物、鱼类和颗粒碎屑 ,各大类食物的出现频率分别为 87.3%、82 %、0 .3%、0 .6 %、48.2 %、2 8.2 %、0 .3%、2 8.7%、88.7%。而不可分辨物在食物团中较为常见 ,出现频

微囊藻毒素的提取纯化方法比较(英文)

研究了从天然蓝藻水华藻粉中提微囊藻毒素,以及对提取物纯化的方法。通过对比不同提取剂的提取效果,发现浓度为80％的甲醇溶液提取效率最高,但采用乙醇作为替代提取剂也有较好的效率,且方法更为安全。对于提取物的纯化,可通过调节溶剂的pH至等电点以除去对反相填料具有负作用的藻胆蛋白。研究结果为更高效地纯化微囊藻毒素提供了依据。

Recycle of transuranium elements in light water reactors for reduction of geological storage requirements

This paper presents results of a feasibility study aimed at developing a zero-transuranic-discharge fuel cycle based on the U-Th-TRU ternary cycle. The design objective is to find a fuel composition (mixture of thorium, enriched uranium, and recycled transuranic components) and fuel management strategy resulting in an equilibrium charge-discharge mass flow. In such a fuel cycle scheme, the quantity and isotopic vector of the transuranium (TRU) component is identical at the charge and discharge time points, thus allowing the whole amount of the TRU at the end of the fuel irradiation period to be separated and reloaded into the following cycle. The TRU reprocessing activity losses are the only waste stream that will require permanent geological storage, virtually eliminating the long-term radiological waste of the commercial nuclear fuel cycle. A detailed three-dimensional full pressurized water reactor (PWR) core model was used to analyze the proposed fuel composition and management strategy. The results demonstrate the neutronic feasibility of the fuel cycle with zero-TRU discharge. The amount of TRU and enriched uranium loaded reach equilibrium after about four TRU recycles. The reactivity coefficients were found to be within a range typical for a reference PWR core. The soluble boron worth is reduced by a factor of ∼2 from a typical PWR value. Nevertheless, the results indicate the feasibility of an 18-month fuel cycle design with an acceptable beginning-of-cycle soluble boron concentration even without application of burnable poisons.