^7Be and ^210pb radioactivity and implications on sources of surface ozone at Mt. Waliguan

Beryllium-7 (^7Be) and lead-210 (^210Pb) radioactivity in aerosols collected, from October 2002 to January 2004 at Mt. Waliguan, by the Global Atmospheric Watch (GAW) Station, Qinghai Province is presented. The data were analyzed together with simultaneously measured surface ozone concentrations. We found that short time variations of ^7Be and ^210Pb were linked to alternations of synoptic weather around the Mt. Waliguan region. ^210Pb showed the lowest concentration in summer while ^7Be showed no obvious seasonal changes. Relatively high ^7Be and ^210Pb radioactivity was observed at Mt. Waliguan when compared with the observations at other mountain sites in other parts of the world. Surface ozone and ^7Be showed a consistent seasonal variation. Surface ozone correlated fairly well with ^7Be/^210Pb ratio. This suggested that vertical transport from higher altitudes of the atmosphere has predominant effects on the budget of surface ozone at Mt. Waliguan.     

Climate change, social unrest and dynastic transition in ancient China

The alternation of war and peace accompanied bydynastic transitions was shown to be the rhythm of socialdevelopments throughout Chinese history. Western schol-ars attempted to use the “Dynastic Cycle” theory to expli-cate why the socio-economic development in China wasembedded in such a historical rhythm[1—4]. Dynastic cycletheory states that any dynastic rise-and-fall, social ac-cord-and-discord, and economic upturn-and-downturn areclosely related to the trend of societal development andt…     

液相臭氧化流动注射化学发光法测定水体化学耗氧量(COD)的研究:苯酚溶液COD测定

研究了紫外光辅助的苯酚臭氧化过程.利用溶解臭氧在水体中能够氧化鲁米诺产生发光现象,我们建立了流动注射液相化学发光测定COD的一种新方法.COD测定工作曲线为 y=34 276 lnx+63 269,线性相关系数为 0.995.线性范围0.6 mg/L到24 mg/L适合地表水COD监测.为了考察臭氧化法测定 COD的可行性,研究了苯酚的臭氧化反应动力学及反应机理,其直接和间接反应速率常数分别为383 mol-1·L·s-1和6.728×109 mol-1·L·s-1.几个实际淡水水样的COD测定结果显示新方法的 3 次测量标准偏差均小于 6%.与高锰酸钾 COD测定方法相比,新方法的结果要高 8.25%~25.82%,这表明紫外光辅助臭氧氧化与高锰酸钾氧化相比氧化能力能强.     

APA油烟净化器的除烟机理

在现有油烟净化技术和应用现状调研的基础上，提出一种新型复合油烟净化器——APA油烟净化器。该净化器具有效率高、阻力小、成本低等优点。为深入研究该净化器的性能，从惯性碰撞、拦截效应、离心沉降、微粒过滤、旋流分离等方面较系统地分析了APA油烟净化器的除烟机理。通过定量的理论分析和比较，发现喷淋洗涤、旋流叶片分离对净化大于5μm的油烟液滴是非常有效的，对于小于1μm的油烟微粒的净化，筛网过滤将起主导作用。这就为改进油烟净化器提供了重要的技术路线。     

火电单元机组智能控制系统

提出了一个实现大范围负荷跟踪的火电单元机组智能控制系统．该系统包括设定值调节器、神经网络模糊前馈控制器、模糊反馈控制器和单元机组．设定值调节器根据机组负荷指令提供设定值．前馈控制器采用神经网络模糊控制逼近单元机组的逆稳态特性而得到前馈控制信号，以实现单元机组的大范围运行．反馈控制器则采用模糊控制补偿负荷扰动所引起的单元机组的实际值与设定值的偏差．前馈控制信号与反馈控制信号相加后发出指令到单元机组完成负荷跟踪任务．仿真结果表明，该系统有较好的动态特性，能适应于机组大范围的负荷跟踪．     

DESIGN SAMPLING AND REPLICATION ASSIGNMENT UNDER FIXED COMPUTING BUDGET

1. Introduction The essence of any decision problem is an optimization problem. Whether it is a decision on the production schedule of a manufacturing plant, a decision on the routing rules of networking, or a decision on the make-up of investment portfolios, the problem always revolves around making a choice from a population of alternatives (either finite or infinite) so as to optimize certain targeted objective. Without loss of generality, the objective can be represented by Mθ ∈iΘn J(…     

Enzymatic assembly of slow reacting substance

When basophils or mast cells are stimulated by a specific antigen they release chemical mediators, including a potent bronchoconstrictor, slow reacting substance of anaphylaxis (SRS-A). The structure of SRS from a mouse mastocytoma and rat basophilic leukaemia (RBL-1) cells has been identified as a thioether or arachidonic acid and glutathione [not a thioether of cystene as was originally thought]. SRS has been named leukotriene (LT) C and may be formed by a novel lipoxygenase pathway which also synthesizes 5,6-oxido-7,9,11,14-icosatetraenoic acid (LTA) and 5,12-dihydroxy-6,8,10,14-icosatetraenoic acid (LTB). Homogenates of RBL-1 cells, when incubated with C-arachidonic acid, form 5-hydroxy-icosatetraenoic acid (5-HETE) and 5,12-dihydroxy- and 5,6-dihydroxy-icosatetraenoic acid. The latter is the spontaneous breakdown product of the labile intermediate LTA. Formation of both compounds is stimulated by calcium. We have now produced biologically active SRS in a cell-free system generated from RBL-1 cells. Glutathione was essential for SRS synthesis and calcium stimulated its formation.     

Zinc-deficiency and activities of urea cycle-related enzymes in rats

Summary In contrast to previous reports, an increase in glutamate dehydrogenase activity and no change in arginase activity were observed in rats fed a zinc-deficient diet for 15 weeks. The discrepancies could be due to a difference in degree and duration of zinc-deficiency.We wish to thank Professor P.M. Newberne for supplying the plastic cages and ingredients for the zinc-deficient diet.