On the convergence of spectral multigrid methods for solving periodic problems

The spectral multigrid method combines the efficiencies of the spectral method and the multigrid method. In this paper, we show that various spectral multigrid methods have constant convergence rates (independent of the number of unknowns in the linear system, to be solved) in their multilevel iterations for solving periodic problems.     

火焰原子发射法测定硝酸铀酰中的微量铯

对铀化物中的杂质元素,化学工作者通常是先将铀基体分离掉,然后再用分光光度、原子吸收等方法进行测定。但,迄今我们没有见到用原子吸收分光光度计以FAES为分析手段的测定铀化合物中铯元素的报道。铯的火焰原子吸收法测定,灵敏度较低。欲用加大样品量的方式去适应测定需要,势必给萃取分离带来困难。而具有较高灵敏度的FAES法可以满足测定要求。因铯的电离电位很低(3.95 eV),测定时存在严重的电离效应的不利影响,我们试图加入钾的硝酸盐予以消除;这一尝试终于取得了令人满意的效果。不过,出于对样品测定时信噪比的考虑,鉴于背景发射随钾盐量增加而增大,因而严格控制其钾的加入量是至关重要的。     

Conversion of oleic acid to 10-ketostearic acid by aStaphylococcus species

In the course of using microorganisms to produce value-added products from soybean oil or its fatty acids, a culture contaminant was isolated and tentatively identified as aStaphylococcus species. This microorganism converts oleic acid (cis-9-octadecenoic acid) to 10-ketostearic acid (10-keto-octadecanoic acid) in growing cultures. Bioconversion was studied in two different media at temperatures from 30 to 41°C, with shaking at 150 rpm. Cells were grown in 50 mL of media for 24 h and then incubated with 0.25 g oleic acid for 24 h. Optimum conditions have allowed better than 90% conversion with 85% recovery. Unreacted oleic acid and 10-hydroxystearic acid (10-hydroxyoctadecanoic acid) are the only other compounds present in the ethyl ether extract of the fermentation broth.     

10MW高温气冷实验堆石墨砖的三维辐照应力分析

为分析快中子辐照和高温等条件下石墨砖在整修寿期内的力学行为，采用改编的ＡＤＩＮＡ和ＡＤＩＮＡＴ程序，计算了１０ＭＷ高温气冷实验堆石墨砖受快中子辐照后所产生的变形和应力历史。计算结果表明，改编后的ＡＤＩＮＡ和ＡＤＩＮＡＴ程序考虑了温度和辐照条件下多个参数的变化，可以用来分析石墨砖在辐照条件下的应力和变形。     

新型耐磨耐热不锈钢GX－10

研制了一种新型１．１Ｃ－１４Ｃｒ－５Ｃｏ－４Ｍｏ－１Ｖ合金（ＧＸ－１０），该合金室温ＨＲＣ６０，５５０℃ＨＲＣ５５，具有高的耐磨耐热耐蚀性能和低的线膨胀系数，ＧＸ－１０合金适于制造５５０℃高速运转的精密偶合部件。     

原子吸收法测定铬交联体系中Cr3+的新方法

所报道的方法用于定量测定铬交联聚合物驱(弱凝胶驱)油藏产出水中的Cr3 。选用还原性火焰原子吸收光谱法测定Cr3 。Cr3 标准溶液由重铬酸钾溶液制备,介绍了制备方法及标准曲线。为了提高测定灵敏度,在4种试剂中筛出了Na2SO4,在2 mL含Cr3 试液中加入1 mL 10%Na2SO4溶液使吸光度由空白时的0.349增加至0.594,加大加入量对吸光度的影响很小。与使用重铬酸钾标准溶液的传统原子吸收光谱法相比,这种新方法测定的3个铬交联聚合物溶液样中的Cr3 质量浓度(706,737,1084 mg/L),与已知值(700,750,1100 mg/L)更加接近。在2个样中进行加标测试,回收率分别为99%和98%,可以满足工业分析要求。图1表4参3。     

新亚铜灵萃取光度法测定机油中铜含量方法的改进

将机油灰化、酸溶解后，新亚铜灵显色、直接光度法测定铜离子含量，样品回收率在92．6％～95．0％，线性范围在0．05～5．0μg／mL，与新亚铜灵三氯甲烷萃取光度法相比，避免使用有毒的三氯甲烷，且显色稳定，2种方法的测量结果没有显著性区别，本法适合于无色溶液中铜离子的测定。     

反式-1-苯磺酰基-2-甲基-4-羟基-2-丁烯的合成

以异戊二烯为原料,经与苯磺酰氯加成、水解乙酰化、皂化3步反应,合成了辅酶Q10的重要中间体——反式-1-苯磺酰基-2-甲基-4-羟基-2-丁烯(简称终产物);分别考察了3步反应的反应条件;用傅里叶变换红外光谱和核磁共振表征了其结构。实验结果表明,加成反应的适宜条件为:氯化亚铜为催化剂,三乙胺盐酸盐为相转移助催化剂,乙腈为溶剂,90～100℃下密闭带压(约0.6M Pa)反应2h,n(异戊二烯)∶n(苯磺酰氯)=1.2,中间产物反式-1-苯磺酰基-2-甲基-4-氯-2-丁烯的收率为75%;水解乙酰化、皂化反应的适宜条件为:120～125℃下常压回流反应4h,0～5℃下碱性水解反应3h,以体积比为1∶1的乙酸乙酯-乙醚混合溶剂进行结晶精制。3步反应终产物的总收率为60%;终产物经液相色谱法分析,纯度达到99%。     

紫外分光光度法同时测定二氧化硫脲和硫脲的含量

用紫外分光光度法，引入两个吸收比后，同时测定二氧化硫脲和硫脲的含量，取得了较为满意的结果。它们的平均回收率分别为１００．６％（ｎ＝９，ＲＳＤ＝０．２％）和９９．３５％（ｎ＝９，ＲＳＤ＝０．４％）。     

On Solving Periodically Perturbed Nonconservative Systems with a One-Parameter Embedding

The paper is concerned with solving the periodically perturbed nonconservative systems, which will be differentiably imbedded into an one-parameter family of operators. The solution of the systems is then found by continuing the solution curve of operator homotopy. When the Newton-Kantorovich's procedure is applied to the corresponding operator equations, an efficient algorithm is derived. Furthermore, the suitable condition on the optimum step size of the parameter is provided for assuring that the approximation solution will converge to the unique solution of the nonlinear periodically boundary value problem. Finally, the theoretical results are in excellent agreement with the numerical examples. Received August 14, 2001; revised December 19, 2001 Published online: November 18, 2002