X射线荧光光谱法测定钢铁材料中硫、磷含量

<正>常用钢材中,硫、磷属于有害杂质元素,硫元素增加钢铁产生"热脆"倾向,磷元素增加钢铁产生"冷脆"倾向。因此,钢材中的磷、硫含量通常要求被严格控制。以压力容器用钢材为例,碳素钢和低合金钢中磷含量要求不大于0.035%、硫含量要求不大于0.035%;低温用钢更为严格,磷含量要求不大于0.020%、硫含量要求不大于0.010%。     

Propane-1,2,3-triyl tris(hydrogen sulfate): A mild and effcient recyclable catalyst for the synthesis of biscoumarin derivatives in water and solvent-free conditions简

A simple, efficient, and ecofriendly procedure has been developed using propane-l,2,3-triyl tris（hydrogen sulfate） as a catalyst for the synthesis of biscoumarin derivatives in water and solvent-free conditions. The significant features of the present protocol are simplicity, environmentally benign, high yields, no chromatographic separation, and recyclability of the catalyst.     

Synthesis of cyclopentenyl and cyclohexenyl ketones via [3 + 2] and [4 + 2] annulations of 1,2-allenic ketones简

In this paper, an efficient synthesis of cyclopentenyl ketones and cyclohexenyl ketones through tertiary phosphine catalyzed [3 ＋ 2] and [4 ＋ 2] annulations of 1,2-allenic ketones with activated alkenes has been developed. Compared with published synthetic methods on cyclopentenyl ketones and cyclohexenyl ketones, the protocols developed in this paper have the advantages such as readily available starting materials, mild reaction conditions and high efficiency.     

Copper-catalyzed N-arylation of 2-arylindoles with aryl halides

10 mol% Cul combined with the DMEDA ligand can efficiently catalyze the N-arylation of 2-arylindoles with aryl iodides and aryl bromides in good to excellent yields. The aryl halides bearing electron-rich or electron-deficient functional groups can be well tolerated under this mild reaction conditions.     

One-pot synthesis of various xanthene derivatives using ionic liquid 1, 3-disulfonic acid imidazolium hydrogen sulfate as an efficient and reusable catalyst under solvent-free conditions

In this study, 1,3-disulfonic acid imidazolium hydrogen sulfate （DSIMHS） is used as an efficient and reusable ionic liquid for the green, mild, and efficient synthesis of xanthenes under solvent-free conditions. Simple and easy work-up, low cost, green process, short reaction times and excellent yields of the products are the advantages of this procedure. Further, the catalyst can be recycled and reused at least for four times without a noticeably decrease in its catalytic activity.     

Synthesis,structure and dielectric properties of a novel Gd coordination polymer based on 2-（ pyridin-4-yl ）- 1H-i midazole-4,B -dicarboxylate

A new Gd coordination polymer based on 2-（pyridin-4-yl）-I H-imidazole-4,5-dicarboxylate （H3PIDC） has been synthesized under hydrothermal conditions, formulated as {[Gd3（HPIDC）3（PIDC）（H2O）4].3H2O}n （1）. The compound crystallizes in the monoclinic system, space group C2/c with a=20.951（7）, b = 9.515（3）, c = 27.483（10） A,β= 106.176（6）°, Z = 4, V= 5262（3） A3, C40 H45 Gd3 N12 O30, Dc = 2.071 g/cm3, Mr=1645.63, λ （MoKa）=0.71073A, μ=3.846mm-1, F（000）=3204, the final R=0.0390 and wR= 0.1332. Complex 1 is a two-dimensional MOF built up from T-shaped 3-connected HPIDC2 , PIDC3 and 4-connected metal nodes. Dielectric constant of complex 1 was measured at different frequencies with temperature variation.     

Synthesis and Crystal Structure of a New Pr(Ⅲ)–K(Ⅰ) Heterometallic Oxalate Coordination Polymer

A new 3D heterometallic coordination polymer, namely [K2Pr2(C2O4)4·H2O]n(1), has been successfully synthesized under hydrothermal conditions. X-ray single-crystal diffraction determination reveals that 1 crystallizes in monoclinic system, space group P21/n with a = 12.060(4), b = 8.493(3), c = 15.776(5)(A), β = 93.235(3)°, V = 1613.4(9) 3, Z = 4, Mr = 730.12, Dc = 3.006 Mg/m3, μ = 6.581 mm-1, F(000) = 1368, the final R = 0.0283 and w R = 0.0866 for 2939 observed reflections with I 2σ(I). Complex 1 features an unusual 3D heterometallic coordination framework, in which oxalates exhibit three different coordination behaviours. Moreover, powder X-ray diffraction and thermal properties for 1 have also been investigated.     

(英)硫酸氢钾高效催化一锅法合成5-未取代的3,4-二氢嘧啶-2(1H)-酮

无溶剂条件下,硫酸氢钾可有效催化芳香醛、苯乙酮衍生物和脲的三组分"一锅法"Biginelli反应来合成5-未取代的3,4-二氢嘧啶-2(1H)-酮。确定了优化反应条件。产品结构经IR、1H NMR、MS和元素分析进行表征。     

固相萃取/气相色谱-质谱法对土壤中有机氯农药的分析及基质效应研究

建立了一种固相萃取/气相色谱-质谱法同时测定土壤中23种有机氯农药的方法,并研究了不同基质效应补偿方式。土壤样品经正己烷∶丙酮(体积比1∶1)提取,弗罗里土小柱净化,采用气相色谱-质谱仪检测。结果发现7种有机氯存在中/强程度的基质效应;在10 mL二氯甲烷∶正己烷(体积比1∶9)+10 mL丙酮∶正己烷(体积比1∶9)为固相萃取的洗脱剂,且脉冲压力为275.8 kPa条件下,可将23种有机氯的基质效应均控制在20%以内。23种有机氯农药在0.4～10μg·mL~(-1)质量浓度范围内线性良好,相关系数(r~2)均不小于0.999 2,检出限为1.0～8.6μg·kg~(-1),定量下限为4.0～34.4μg·kg~(-1);在20、60、100μg·kg~(-1)3个加标水平下空白土壤中的平均回收率为46.3%～127%,相对标准偏差(n=6)为0.68%～15%。采用该方法在某土壤样品中检出α-六六六、γ-六六六、p,p′-DDE、异狄氏剂醛、p,p′-DDT 5种有机氯农药。     

磁单极与磁洛伦兹力

概述了磁单极概念的历史发展,从洛伦兹变换出发,利用电磁场张量和四维力的协变性以及电荷相对论不变,直接证明了运动磁单极受磁洛伦兹力,建议了一个磁洛伦兹力的验证方案,并用磁洛伦兹力公式导出狄拉克电荷量子化条件．证明了磁洛伦兹力公式具有与库仑定律相同的精确度．