铀氧化物中238U含量的定量研究

准确定量铀氧化物样品中238U的含量对于裂变产额测量等工作具有重要意义,其定量方法的研究对于涉及238U的绝对测量的诸多实验都具有参考价值。利用四川大学2.5 MeV质子静电加速器产生的准单能中子对八氧化三铀样品进行中子活化,用高纯锗探测器测量活化产物的β衰变子体239Np的277.6 keV特征γ射线,利用已知的活化截面,算出样品中238U的质量占比为79.1%,不确定度为6.2%。利用电感耦合等离子体质谱法对样品中238U的含量进行了测量,其质量占比为59.2%。此外,基于EA3000元素分析仪、卡尔费休电位滴定仪和TGA-DSC2同步热分析质谱联用仪,测知样品中不含N元素,含水量在2.2%以下。并利用PIXE方法排除了样品中含有Al元素以上杂质,利用EPBS方法测知样品中U/O原子数比为1:3.6,误差约2%,推知样品中238U质量占比为80%,验证了活化法测得的238U含量。最终测得样品中238U的质量占比为79.1%,不确定度6.2%。对照按U3O8分子式折算的84.5%,考虑到水分含量等,此结果合理。The accurate quantification of 238U in uranium oxides is of great importance for measurements of fission yield. The study for the method of 238U quantification has significance to lots of experiments involving absolute measurement of 238U. The reaction (n, γ) in the triuranium octoxide samples was induced by T(p,n)3He quasi-monoenergetic neutrons provided by the 2.5 MeV proton electrostatic accelerator in Sichuan University. The 277.6 keV characteristic γ ray of 239Np that comes from β-decay of the activation product 239U was detected by a HPGe detector. With the known (n, γ) cross section, the mass percentage of 238U in samples was determined to be 79.1%, with the uncertainty of 6.2%. ICP-MS was also used in the quantification of 238U in samples, its result was 59.2%. Meanwhile, the samples were analyzed by other several methods and the results showed that less than 2.2% H₂O, no nitrogen, and no other impurity elements above Al were contained in the samples. EPBS was used to measure the atomic ratio of U and O and it was found that the mass percentage of 238U in samples was about 80%, verifying the result 79.1% of INAA.     

本科生综合化学实验设计:水系锌离子电池组装与测试

将柔性电极的制备以及电池组装引入本科教学实验,使学生体验电池组装及测试全过程。以电沉积制备柔性电极材料为正极,Zn箔为负极,完成全流程构筑柔性Zn-MnO₂电池器件。该实验安全性高,成本低,条件温和,常温常压下即可完成。通过充放电测试、循环伏安法测试等,计算所制备电极的质量能量密度。且电池在不同弯曲条件下,可以点亮LED灯泡。本实验内容丰富,有助于学生综合技能的提升和科学思维的培养,更加贴合现代化学学科发展,使学生更清晰地理解电化学储能相关概念,该实验可作为化学类、材料类本科生专业综合性实验开设。     

在流动体系中He（2^3S）与SOCl2的碰撞传能动力学研究

本文利用流动余辉技术研究了亚稳态Ｈｅ（２＾３Ｓ）与ＳＯＣｌ２的碰撞传能反应，测定了反应产物碎片ＳＯ（Ａ）的形成速率。通过加ＳＦ６检验，表明ＳＯ（Ａ）的形成主要为直接解离激发过程，由外推法估算了ＳＯ（Ａ）的初生态布居，通过观察光谱强度随压力的变化，研究了激发碎片的碰撞弛豫过程。     

有限域上的绝对迹函数和原根

设p是一个素数,m>0整数,GF(p~m)是有p~m个元素的有限域,T(x)=x+x~p+…+x~(p~(m-1))为GF(p~m)上的绝对迹。R_(p~m)(h)表示T(x)=h(h∈GF(p))在GF(p~m)中的本原根解数。本文证明了如下结果: (ⅰ)R_(p~m)(o)≥φ(p~m—1)/p(p~m—1){p~m—(2~(ω(p-1/p-1))-1)(p-1)p~m(1/2)-p}, (ⅱ)R_(p~m)(h)≥φ(p~m-1)/p(p~m-1){p~m-(2~(ω(p-1/p-1))-1)p~m(1/2)-(2~(ω(p-1))-2~(ω(p-1/p-1))p~(m+1)},其中h≠0,ω(n)表示n的不同素因子个数,φ(n)表示通常的Euler函数。 (ⅲ)当m≥3时,对任给的p和h≠0,h∈GF(p)。除p~m=11~3外,总有R_(p~m)(h)>0。     

关于丢番图方程 x~4-Dy~2=1

<正> 关于丢番图方程x~4-Dy~2=1,D>0且不是平方数,(1)有过一系列工作,其主要结果如下:Nagell 证明了 D≡3(mod 8)是素数,(1)无正整数解.Ljunggren 证明了(1)最多只有两组正整数解.Cohn 证明了 D 使得 x~2-Dy~2=-4有解 x≡y≡1(mod 2),则(1)除开有限个D 的值外,仅有整数解 x=1.     

关于方程sum from j=1 to s 1/xj+1/(xj…xs)=1

For the equation sum from j=1 to s 1/x_j+1/(x_j…x_s)=1,11<…s and the system of congruences.     

有限群中一个未解决的丢番图方程

在文[1]中,我们曾介绍在有限群的研究中提出的二个丢番图方程 (1) P~m-2q~n=±1,p、q是素数,m>1,n>1的求解问题,并提到Crescenzo在文[2]中证明了定理:除开239~2-2.13~4=-1以外,方程(1)如有放,则m=n=2。 最近发现3~5-2.11~2=1也满足方程(1),因此,上述Crescenzo的定理是错的。错误产生的原因在于该文引理1用了论断:“1 ωq~k(其中k相似文献   

ENERGY TRANSFER IN THE PIGMENTS OF Anabaena azotica Ley

The absorption, fluorescence emission and excitation spectra of algal suspension of Anabaena azotica Ley were measured. The fluorcscence spectra were measured at 293 K and 77 K. The wavelengths of excitation light were 430 nm, 475 nm, 615 nm and 650 nm. The spectra were compared after the algal suspensions were treated as below: (ⅰ) 0.04, 0.08, 0.12 0.16 and 0.20 μm DCMU; (ⅱ) 5, 10, 15, 20 and 25μm O-phcnanthroline; (ⅲ) 0.8 M Tris (pH 7); (ⅳ) 2, 5 and 8 mM hydroxylamine; (ⅴ) heating at 60°C for 4, 8, 12, 16 and 20 rain; (ⅵ) divalent, cations Mg~(++), Ca~(++) and Zn~(++). All these treatments affected the relative fluorescence intensity and the ratio of intensites of the peaks in the spectra. The data showed the possible route of energy transfer from earotenoids and phyeobilins to ehlorophylla a and the relation between pigments and protein.     

靶向β-半乳糖苷酶光学探针的研究进展

β-半乳糖苷酶是细胞溶酶体中的一种水解酶,广泛存在于植物、细菌、真菌以及哺乳动物中,它可催化糖苷键水解,从而将乳糖转化为半乳糖.研究表明,β-半乳糖苷酶的过量表达与原发性卵巢癌的发生、发展以及细胞的衰老密切相关.因此,灵敏检测β-半乳糖苷酶的活性在生命医学领域具有重要意义.近年来,荧光探针因其高灵敏度、高选择性和高时空...     

有限域上存在弱自对偶正规基的一个充要条件

对于将有限域上的自对偶基概念推广到了更一般的弱自对偶的情形,给出了有限域上存在这类正规基的一个充要条件设q为素数幂,E=Fqn为q元域F=Fq的n次扩张,N={αi=αq2| i=0,1,…,n-1}为E在F上的一组正规基.则存在c∈F*及r,0≤r≤n-1,使得β=cαr生成N的对偶基的充要条件是以下三者之一成立(1)q为偶数且n≠0(mod 4);(2)n与q均为奇数;(3)q为奇数,n为偶数,(-1)为F中的非平方元且r为奇数.