The GENIUS-test-facility—first results on background from Rn daughters

GENIUS-TF (Nucl. Instr. and Meth. A 511 (2003) 341; Nucl. Instr. and Meth. A 481 (2002) 149.) is a test-facility for the GENIUS project (GENIUS-Proposal, 20 November 1997; Z. Phys. A 359 (1997) 351; CERN Courier, November 1997, 16; J. Phys. G 24 (1998) 483; Z. Phys. A 359 (1997) 361; in: H.V. Klapdor-Kleingrothaus, H. Pas. (Eds.), First International Conference on Particle Physics Beyond the Standard Model, Castle Ringberg, Germany, 8–14 June 1997, IOP Bristol (1998) 485 and in Int. J. Mod. Phys. A 13 (1998) 3953; in: H.V. Klapdor-Kleingrothaus, I.V. Krivosheina (Eds.), Proceedings of the Second International Conference on Particle Physics Beyond the Standard Model BEYOND’ 99, Castle Ringberg, Germany 6–12 June 1999, IOP Bristol (2000) 915), a proposed large scale underground observatory for rare events which is based on operation of naked germanium detectors in liquid nitrogen for an extreme background reduction. Operation of naked Ge crystals in liquid nitrogen has been applied routinely already for more than 20 years by the CANBERRA Company for technical functions tests (CANBERRA Company, private communication, 5 March 2004.), but it never had found entrance into basic research. Only in 1997 first tests of application of this method for nuclear spectroscopy have been performed, successfully, in Heidelberg (Klapdor-Kleingrothaus et al., 1997, 1998; J. Hellmig and H.V. Klapdor-Kleingrothaus, 1997).

On May 5, 2003 the first four naked high-purity germanium detectors (total mass 10.52 kg) were installed in liquid nitrogen in the GENIUS Test Facility at the Gran Sasso underground laboratory. Since then the experiment has been running continuously, testing for the first time the novel technique in an underground laboratory and for a long-lasting period.

In this work, we present the first analysis of the GENIUS-TF background after the completion of the external shielding, which took place in December 2003. We focus especially on the background coming from ²²²Rn daughters. This is found to be at present by a factor of 200 higher than expected from simulation. It is still compatible with the scientific goal of GENIUS-TF, namely to search for cold dark matter by the modulation signal, but on the present level would cause serious problems for a full GENIUS—like experiment using liquid nitrogen.     

The current and residual value of superphosphate for lupins grown in rotation with oats and wheat on a deep sandy soil

In a field experiment on a deep pale-yellow sand in a 600 mm per annum rainfall Mediterranean environment of south-western Australia, six levels of phosphorus (P) as superphosphate (O up to 546 kg P ha^–1) were applied once only, to the soil surface, before sowing lupins (Lupinus angustifolius). The lupins were grown in a continuous arable cropping rotation with, in successive years, oats (Avena sativa), wheat (Triticum aestivum), lupins. Five such rotations were started in the experiment from 1985 to 1989. The experiment continued until the end of 1990.The relationship between lupin seed (grain) yields and the level of P applied was measured in the year of P application for five successive years (1985 to 1989). The relationship had the same general form but it varied between years, largely due to different maximum yields (yield plateaux) in each year.The residual value of superphosphate applied three years previously was measured for lupins on two occasions (1988 and 1989) relative to superphosphate applied in the current year. The residual values was different in the two years. The superphosphate applied three years previously was about 30% as effective as freshly applied superphosphate in 1988, and 12% as effective in 1989.At each harvest, the relationship between grain yield and the P concentration in the grain differed for different species. However, for each species at each harvest, the relationship was similar regardless of when the P was applied in the previous years. Thus each species had the same internal efficiency of P use curve, and yields varied only with P concentration in tissue.Bicarbonate-extractable soil P was determined on soil samples taken in mid-July of 1989 and 1990. These soil test values were related to grain yields at harvest. The relationship between yield and soil test values had the same general form but varied for different species within years and for each species between years. It also varied for each species within years depending on the year the P was applied.     

Hydrolysis of fats and oils with moist oat caryopses

To improve the economic feasibility of hydrolyzing fats and oils with moist oat caryopses, various factors affecting the efficiency of the process were studied. Caryopses produced with an impact-type dehuller exhibited greater lipase activity than those produced by a wringer-type dehuller. Abrasion of oat caryopses against each other in a fluidized bed released particles rich in lipase. Such lipase concentrates could be added to moist caryopsis reactors to speed fat hydrolysis. Beef tallow, lard, soybean oil and crambe oil were hydrolyzed more efficiently than corn oil, castor oil and milk fat. The poor hydrolysis of castor oil was attributed to the formation of esters with the hydroxy group of ricinoleic acid, and the hydrolysis of castor oil was increased by dilution of the substrate with hexane. Diglycerides inhibited the hydrolysis and accounted for the slower hydrolysis of corn oil. Hydrolysis of milk fat by moist oat caryopses resulted in preferential hydrolysis of C₆ to C₁₀ acids. Erucic acid was released from crambe oil at significantly slower rates than the other acyl groups. High conversions of fats and oils to free fatty acids could be attained by (i) exposing the fats and oils to two to three lots of moist caryopses, (ii) the use of special oat varieties with elevated lipase content, (iii) the addition of oat lipase concentrates to moist caryopsis reactors, and (iv) dilution of the substrate with hexane. Estimates of the cost of producing free fatty acids with these processes indicated that the first three should be profitable. Growth ofClostridium sporogenes spores could not be demonstrated in caryopsis reactors. During the incubation of moist oat caryopses immersed in oil, the free fatty acid content of the internal caryopsis lipid increased only slightly, but there were changes in its fatty acid composition.     

裸置海底自沉降热油管道泄漏扩散的数值研究

根据计算流体力学建立海底海泥区域与海水区域的流固耦合传热多相流模型,海泥区域视为饱和含水多孔介质。运用软件模拟了裸置在海底的热油管道在输送过程中泄漏后原油在海泥和海水中的分布情况和温度场的变化情况,并对不同的泄漏点进行了分析。模拟时考虑了裸置海底管道的自沉降和海水中压强的影响。模拟结果表明,泄漏点对泄漏原油的扩散分布有很大影响;当泄漏点在土壤区域开始泄漏时,原油在土壤中呈弧形分布,过一段时间后沿土壤与管道外保温层流入海水中,顶端呈现喷射形,两侧呈螺旋状,并逐渐向海面流动;当泄漏点在海水区域时,泄漏的原油呈现喷射形,在浮力的作用下逐渐向海面流动;泄漏位置不同,海水和海泥温度场的分布有很大差异。海水区域和海泥区域的交界面对原油分布和温度场分布有很大影响。     

架空平行集束导线的运用及推广

国家电力公司为进一步加强科技进步工作，提高农网的科技含量，以保证农网安全、经济、可靠的运行，在农村低压配电网建设与改造方面，大力采用新技术、新设备。扩大试点的架空平行集束导线供电模式，就是这项工作的重要内容之一。本文就架空平行集束导线与裸导线的经济技术比较及显著的防窃电性能进行阐述，指出在农网改造中应广泛采用该项新技术。     

莜麦淀粉的提取工艺优化及其相关特性研究

确定应用脱脂碱提复合法进行莜麦淀粉提取的最佳工艺,并对其相关特性进行研究。以莜麦种子为原料,通过单因素以及正交实验确定莜麦淀粉提取的最佳工艺并对莜麦淀粉相关特性进行研究。最佳工艺为：当固液比为1:10,摇床温度为50℃,震摇时间为2 h,测得莜麦淀粉的提取率为73.26%。在最优条件下,提取的莜麦淀粉中水分含量为7.56g/100g,灰分含量为0.13 g/100 g,脂肪含量为0.17g/100 g,蛋白质残留量为0.56g/100 g,符合国家食品安全标准;SEM和光学显微镜图像显示,莜麦淀粉颗粒较小,且粒径大小不一致,呈多角型或椭圆形,属于小颗粒淀粉;红外光谱与核磁共振分析发现,莜麦淀粉的谱图为典型的淀粉图谱。应用脱脂碱提复合法进行莜麦淀粉的提取,并对其相关特性进行研究。     

添加胡萝卜、燕麦及葵花籽油替代猪背膘对低脂乳化肠品质的影响

研究了添加胡萝卜、燕麦及用葵花籽油替代部分猪背膘对低脂乳化肠(脂肪添加量7%)质构特性、持水特性、色泽及感官品质的影响。单因素实验结果表明,添加胡萝卜10%、燕麦1%及葵花籽油替代动物脂肪50%可较好的改善低脂乳化肠的品质,乳化肠硬度、咀嚼性及弹性与对照组C(脂肪添加量20%)相比差异不显著(p>0.05),持水特性及色泽也得到明显改善(p<0.05),产品的感官评分与对照组C相比更令人满意。在单因素实验的基础上采用两因素(胡萝卜添加量、植物油替代率)三水平设计,进一步优化配方,结果表明,添加胡萝卜12.5%、燕麦1%及用葵花籽油替代猪背膘45%为最优配方,按照此配方生产出的低脂乳化肠恢复到对照组C的质构特性,产品的弹性及感官品质甚至优于对照组C。     

Oat lipids

Oats are a significant world crop. While nutritional interest in food oats has concentrated on oats as a source of dietary fiber, the lipid component has both nutritional and technological potential. Thus, the lipid fraction of the oat grain determines in large measure its energy content and has a significant impact on nutritional quality. The oat lipids mediate the pasting properties of oat starch and hence influence functionality. Lipids are also implicated in the flavor/off-flavor attributes of oats. These aspects of oat lipids are reviewed together with analytical methods for assessing the lipid content of oats.     

Effect of beta-glucan from oats and yeast on serum lipids

Heart disease is the leading cause of death in the U.S. One way to reduce the risk of developing the disease is to lower serum cholesterol levels by making dietary changes. In addition to reducing intake of total fat, saturated fat, and dietary cholesterol, serum cholesterol can be further reduced by added fiber, especially from sources rich in beta-glucan. In this review, two sources of beta-glucan are described; one source is oats and the other yeast. Their chemical structures and physical properties are compared, and their effect on serum lipid levels is described. Oat beta-glucans are found in various breakfast cereals and snacks. Usually, several servings of these products are required to meet the Food and Drug Administration's claim of reducing the risk of heart disease. The yeast-derived fiber is a more concentrated source of beta-glucan than the oat product. It is currently being tested in a wide variety of food products.