rIL—1和rIL—2对浓缩铀UO2F2的防护作用

本文介绍用3H-TdR 掺入示踪技术,探讨了外源性白细胞介素-1(rIL-1)和外源性白细胞介素-2(rIL-2)对浓缩铀 UO_2F_2损伤小鼠脾脏 B 淋巴细胞的防护作用。经 BALB/c 小白鼠尾静脉注入20mg/kg 体重的浓缩铀 UO_2F_2 48 h 后,无菌取脾,制成单细胞悬液加入细菌脂多糖(LPS)、rIL-1或 rIL-2常规培养,以淋巴细胞 DNA 中~3H-TdR 掺入量的变化来衡量 B 淋巴细胞的增殖能力。结果表明,浓缩铀 UO_2F_2能明显抑制小鼠脾脏 B 淋巴细胞 DNA 的合成,使 B 淋巴细胞增殖受到明显抑制;rIL-1和 rIL-2可使受浓缩铀 UO_2F_2损伤的小鼠脾脏 B 淋巴细胞的增殖抑制部分逆转,最大增殖率分别为67%和51%;二者合并使用时可使增殖率增至83%。     

全球治水模式思辨与发展展望

近百年来全球治水取得了巨大成就,为保障可持续发展提供了关键支撑;然而,全球水问题愈演愈烈,亟待进一步创新治水模式。结合水问题发展历程,剖析了水问题的根本症结;从治水目标、总体路径和治理措施等方面解析了全球治水模式的不足,认为当前的全球治水模式未能充分融合水循环及多要素过程的自然属性,存在末端治理和过程分离等突出问题。对下一步治水模式提出了发展建议:从耦合流域水循环多过程互馈机制的角度,提升自然属性和自然力的作用,协调多要素多过程的功能,建设富自然-功能协调流域,系统治理复杂水问题。     

TRANSFERENCE AND ACCUMULATIVE PECULIARITY OF ENRICHED URANIUM IN ORGANISM

Studies show that 235UO2F2 was chiefly localized in kidneys, then in skeleton and liver. Its radioactivity in skeleton rose steadily while the concentration in kidneys and liver droped. 235UO2F2 was difficult to pass through the blood- testes barrier. With 1 to 6 h contact period, only 1.4-1.6 % 235UO2F2 was found in the intact skin, but 41-54 % in the abrasive skin. The dynamic retention of 235UO2F2 through intact or abrasive skins was also dominantly localized in kidneys, skeleton and liver. Accumulation of insoluble 235U3O8 in gastrointestinal tract was well described by a double- exponential- term expression. Values of retention were estimated for fast component T1= 0.34 d, and for relatively long term component T2= 4.05 d.     

On using enriched cover function in the Partition-of-unity method for singular boundary-value problems

 Amongst the various approaches of `meshless' method, the Partition-of-unity concept married with the traditional finite-element method, namely PUFEM, has emerged to be competitive in solving the boundary-value problems. It inherits most of the advantages from both techniques except that the beauty of being `meshless' vanishes. This paper presents an alternative approach to solve singular boundary-value problems. It follows the basic PUFEM procedures. The salient feature is to enhance the quality of the influence functions, either over one single nodal cover or multi-nodal-covers. In the vicinity of the singularity, available asymptotic analytical solution is employed to enrich the influence function. The beauty of present approach is that it facilitates easy replacement of the influence functions. In other words, it favors the `influence-function refinement' procedure in a bid to search for more accurate solutions. It is analogous to the `p-version refinement' in the traditional finite-element procedures. The present approach can yield very accurate solution without adopting refined meshes. As a result, the quantities around the singularity can be evaluated directly once the nodal values are solved. No additional post-processing is needed. Firstly, the formulation of the present PUFEM approach is described. Subsequently, illustrative examples show the application to three classical singular benchmark problems having various orders of singularity. Results obtained through mesh refinements, single-nodal-cover refinements or multi-nodal-cover refinements are compared. Received: 5 November 2001 / Accepted: 21 May 2002     

Enriched‐Air Gasification of Refuse‐Derived Fuel in a Fluidized Bed: Effect of Gasifying Conditions and Bed Materials

Enriched‐air gasification of refuse‐derived fuel (RDF) was carried out in a fluidized bed, investigating the effects of temperature, equivalence ratio (ER), oxygen percentage of enriched air (OP), and bed materials. For the bed material effect, calcined dolomite proved to be more effective for tar decomposition and resulted in higher CO and H₂ contents. In a bed of high‐alumina bauxite, an increased ER tended to cause a greater decrease in syngas quality. For both bed materials, a higher temperature and OP favored the production of combustible gas and led to higher cold gas efficiency. Increasing the ER resulted in higher gas yields and carbon conversion but lowered the concentration of the combustible component. The ash content of the char increased with temperature and OP, while the volatile and fixed carbon contents were decreased. The optimum conditions suggested in this study were an ER of 0.22 and an OP of 44.7 % at 750–800 °C in a bed of calcined dolomite.     

SPAH钢集装箱板连铸坯加热氧化特性

通过实验室箱式电阻炉对SPAH钢(%:0.05C、0.25Cu、0.12Ni、0.41 Cr)连铸坯试样进行900～1 250℃,20 min氧化试验,并用扫描电镜和X-射线能谱仪观察和分析了试样氧化层的组织和成分。结果表明,随加热温度增加,钢的氧化速度急剧增加,同时氧化层中的Cu富集相增加;≤1 000℃加热时,晶界氧化占主导,1 000℃以上加热,晶内氧化占主导。因此SPAH钢集装箱板连铸坯加热时,应减少高温段的加热时间,以便减少氧化烧损。     

Semigroups of matrices with dense orbits

We give examples of n?×?n matrices A and B over the field 𝕂?=?? or ? such that for almost every column vector x?∈?𝕂 ⁿ , the orbit of x under the action of the semigroup generated by A and B is dense in 𝕂 ⁿ .     

金针菇富硒薜荔汁复合饮料的研制

用金针菇Fr19菌丝体液体培养富硒，硒浓度为10μg／ml时富集率最高，用试验确定了复合饮料最佳配方，金针菇菌丝提取液、薜荔汁液、白砂糖、柠檬酸为20％、15％、2％、0．2％。该饮料具有人体吸收率高的生物硒，对人体安全无害，同时具有金针菇菌体蛋白、多糖体、薜荔汁等丰富的营养成份，为研制功能型复合保健饮料提供了实验模型。     

渐近伪压缩半群公共不动点的强收敛结果

在实Banach空间中研究渐近伪压缩半群公共不动点的强收敛性问题,提出黏制迭代算法,并且证明了该公共不动点是一个变分不等式的唯一解.所得结果将文献[8]中的结果从Halpern迭代算法推广到了粘制迭代算法,将文献[9]中的结果从非扩张半群推广到了渐近伪压缩半群.     

Study of the Streaming Operator with General Maxwell's Boundary Conditions

We study the streaming operator in slab domain with general Maxwell's boundary conditions described by linear boundary operators K⁺ and K^–. We prove that the streaming operator generates a strongly continuous semigroup. We show that the positivity and irreducibility of the boundary operators imply the positivity and irreducibility of the generated semigroup. We establish the spectral properties of the streaming operator and characterize its spectral bound. Under the compactness of boundary operators, we explicitly give the essential type of the generated semigroup and describe its asymptotic behavior in the operator norm topology.