一台300kV电子帘加速器辐照箱屏蔽物理设计

介绍一台电子能量为 30 0keV、束流强度为 6 0mA的电子帘加速器辐照箱的屏蔽物理设计。箱体厚度为 1.5cm的铅。

Magnets for HIRFL-CSR rings

The magnet design, fabrication, and measurement of HIRFL-CSR (Heavy Ion Research Facility in Lanzhou Cooling Storage Ring) are presented. All magnets will be laminated And welded with an armor-coated surface between two big endplates made of sticking glue 0.5 mm-thick sheets. The dipole of CSRm was chosen an H type with an air circle on the pole to improve the field uniformity. The dipole of CSRe was chosen the C type with an air circle and two air slots on the pole to improve the field homogeneity. Its reproducibility of magnet to magnet was adjusted with inserting small laminating pieces before demountable pole ends to reach less than +/- 2 x 10(-4) at optimized field level. CSRm quadrupoles diameter is 170 mm and has two different lengths, and its endplates were made with punching pieces after coating with epoxy glue, there is chamfered directly on the pole ends to reduce 12th-order contribution of field and without the demountable pole ends. CSRe main quadrupoles diameter is 240 mm and has two different lengths, and its endplates were also made with punching pieces coated with epoxy glue, there is also chamfered directly on the pole ends to reduce 12th-order contribution of field like CSRm.

The stripper design and test at HIRFL-CSR

Charge stripping is employed to produce multi-charged ions for injecting the cooling storage ring After penetrating through the carbon foil, the widened distribution of ion charge states poses a limit to the ion injection Therefore, the carbon foil plays a key role in the charge snipping injection In this paper, foul strippers for Heavy Ion Research Facility at Lanzhou (HIRFL) and Cooling Sun age Ring (CSR) are introduced The charge state distribution of the stripped ions is measured and the stripping efficiency of the foils is investigated The experimental results are consistent with the theoretical values

非晶态合金的表面辐照效应研究

本工作用120Kev的He~+离子对非晶态Ni_(60)Nb_(40)、Fe_(40)Ni_(38)Mo_4B_(18)、Fe-Ni-B合金样品进行了辐照，辐照剂量为1.6、2.0、2.5，3.0 * 10~(18)/cm~2四种。借助X射线衍射扫描电子显微镜（SEM），内转换电子穆斯堡文谱（CEMS）等方法对辐照前后的样品进行了分析。X射线衍射结果表明在冷却靶的辐照条件下，样品辐照前后的非晶状态来改变，但辐照产生了原子的重排。SEM研究发现：表面发论的形成须一定的临界剂量对于Ni_(60)N_(240)，所需临界剂量最高；随剂量的增加，在所研究的剂量范围内，发论大小增大且来观察到表面发论的破裂与剥学；对不同组织的非晶合金，其发论程度稍有不同；辗压减药不影响材料的发论性质；表面结构的粗糙有助于降低发论程度；晶化样品，发论程度的显加剂。CEMS分析指出；辐照使结构的天度增加，有效的平均原子间距减小；因辐照导致原子的重新溶合使CSRO降低；随辐照首先的缺陷周围自旋取向及急进的应力源的变化。磁各向异性发生了变化

CAPRICE源磁场改进和冷阴极电子枪的应用及激光离子源的初步实验

在本文第一部分主要描述了ECR离子源的现状、发展和重要物理机制，着重介绍了CAPRICE 10GHz ECR源磁场构形的改进，使其Ar~(8+)离子束流增强了约20%且注入级和引出级线包的电功率消耗分别降低10%和20%。当把冷阴极电子松应用于CAPRICE源中时，Ar~(8+)离子束流入140μA增加到240μA微波功率也有明显降低。所有这些结果都表明ECR源对于气体或已产生的固体蒸气是一个很好的离化装置，为了将激光技术应用于ECR源中来产生固态元素离子，我们又开展了激光离子源的研究.在第二部分则介绍了激光源的现状、发展和激光产生等离子体的物理过程，并详细研究了激光参数及掺气对激光等离子体的影响，在实验中，当用磁镜场或磁Cusp场约束激光等离子体时，离子总束流峰值增加了约5倍；而在激光产生等离子体后附加上高频再游离装置时，同样也使总束流峰值从460μA增至1.4mA，这些低电荷态离子数量足以使ECR源产生需要的高电荷态离子输出

不同森林植被下土壤活性有机碳含量及其季节变化

通过对湖南省会同县地区不同季节地带性常绿阔叶林、杉木纯林、火力楠纯林以及杉木火力楠混交林土壤各活性有机碳的含量测定,分析了森林植被对土壤活性碳库及其季节变化的影响。结果表明,常绿阔叶林转变为人工林后,土壤活性有机碳含量明显降低;与杉木纯林相比,火力楠与杉木混交可提高土壤活性有机碳含量,但只有土壤水溶性有机碳含量显著提高;各林地土壤活性有机碳具有明显的季节变化,一年中土壤水溶性有机碳含量的大小始终为常绿阔叶林>杉木火力楠混交林>火力楠纯林>杉木纯林,土壤微生物量碳、热水浸提有机碳和碳水化合物则表现为常绿阔叶林>火力楠纯林>杉木火力楠混交林>杉木纯林。与杉木纯林相比,杉木火力楠混交林可提高林地质量,但不同林地活性有机碳的季节变化规律表现不尽一致,表明土壤活性有机碳的季节差异不仅与温度、降雨等气候因素有关,还受到植被类型的影响。

Degradation mechanism of polystyrene sulfonic acid membrane and application of its composite membranes in fuel cells

The lifetime behavior of a H-2/O-2 proton exchange membrane (PEM) fuel cell with polystyrene sulfonic acid (PSSA) membrane have been investigated in order to give an insight into the degradation mechanism of the PSSA membrane. The distribution of sulfur concentration in the cross section of the PSSA membrane was measured by energy dispersive analysis of X-ray, and the chemical composition of the PSSA membrane was characterized by infrared spectroscopy before and after the lifetime experiment. The degradation mechanism of the PSSA membrane is postulated as: the oxygen reduction at the cathode proceeds through some peroxide intermediates during the fuel cell operation, and these intermediates have strong oxidative ability and may chemically attack the tertiary hydrogen at the a carbon of the PSSA; the degradation of the PSSA membrane mainly takes place at the cathode side of the cell, and the loss of the aromatic rings and the SO3- groups simultaneously occurs from the PSSA membrane. A new kind of the PSSA-Nafion composite membrane, where the Nafion membrane is bonded with the PSSA membrane and located at the cathode of the cell, was designed to prevent oxidation degradation of the PSSA membrane in fuel cells. The performances of fuel cells with PSSA-Nafion101 and PSSA-recast Nafion composite membranes are demonstrated to be stable after 835 h and 240 h, respectively.

Phytoecdysteroid constituents from Cyanotis arachnoidea

Four phytoecdysteroids that have only 19 or 21 carbons, named 11alpha-hydroxyrubrosterone (1), dihydroxyrubrosterone (2), rubrosterone (3) and poststerone (4), were isolated from the whole plant of Cyanotis arachnoidea C.B. Clarke. Among them, 1 was a new compound. Their structures were elucidated by spectroscopic methods.

大兴安岭西北坡火烧迹地湿地格局变化及其影响因子研究

选取大兴安岭1987年特大森林火灾主要过火区的图强林业局育英和奋斗两林场作为研究区,利用地理信息系统软件,对其火后湿地格局变化以及森林水文功能恢复状况进行了分析。结果显示,与过火前相比湿地面积增加了77.56%,且分布趋于集中;森林的平均水文调节能力已得到初步恢复,但具有较高调节能力的林地所占面积有所减少;森林的水文调节能力、地形因子以及火烧强度对湿地分布格局的变化均有明显影响。在森林水文调节功能下降地区、地势较低的谷地,坡度平缓的坡地以及火烧强度较大的地区,湿地面积增加明显。

Multi-walled carbon nanotubes supported Pt-Fe cathodic catalyst for direct methanol fuel cell

Multi-walled carbon nanotubes supported Pt-Fe cathodic catalyst shows higher specific activity towards oxygen reduction reaction as compared to Pt/MWNTs when employed as cathodic catalyst in direct methanol fuel cell.

过量Mg~(2+)对农作物种子萌发特性的影响

[目的]揭示过量Mg2+对玉米和大豆萌发特性的影响。[方法]设0、40、80、120、160、200、240、280、320、360、400 mmol/L11个Mg2+浓度处理,研究不同处理对玉米和大豆发芽势、发芽率、鲜重、干重、根长、株高、茎粗等指标的影响。[结果]随着Mg2+浓度的升高,玉米的发芽被延缓,而大豆发芽率降低明显,达到0.05水平的显著性差异。随着Mg2+浓度升高,玉米和大豆的鲜重和干重降低,但均表现出一定的适应性。玉米和大豆幼根和幼苗生长受Mg2+抑制明显,普遍表现出萎缩、发育不良现象。[结论]过量Mg2+胁迫对不同农作物的发芽势、发芽率影响不同,对农作物的根、茎器官生长毒害作用明显。