学史明理 学史增信*——以“奇妙的二氧化碳”教学中的科学史实情境应用为例

以人类认识二氧化碳知识的形成与发展史实为问题线索和教学主线,进行教学情境设计,探索利用科学史知识,从宏观认识上提升学生对二氧化碳性质的理解,促进学生初步建立学习常见物质的基本思路和方法的有效路径,为初中化学教师教学提供参考借鉴。     

Synthesis,Structure and Photoluminescence of Co-crystal of Bis[2-(benz(oxa/imida)zol-2-yl)phenolato-κ2N,O]zinc(Ⅱ) Being Site Occupancy Disorder with a Heteroatom Ratio of NH to O (0.408/0.592)

The zinc(Ⅱ) complex with Hpbx (Hpbx = 2-(benzoxazol-2-yl)phenol) and Hpbm (Hpbm=2-(benzimidazol-2-yl)phenol),namely[Zn(pbm)2]1.633[Zn(bpx)2]2.367·DMF·2H2O1,has been synthesized and characterized by X-ray crystallography,FTIR and elemental analysis.The coordination structures are statistically disordered and can be regarded as a co-crystal of [Zn(pbm)2]and [Zn(pbx)2] with the ratio of ca.0.408/0.592.Solvate water and DMF molecules are also present in the lattice.Crystal data for 1:monoclinic,space group P21/c,Mr= 2049.02,Z = 2,α = 9,7571(6),b = 25.6415(16),c = 19.8675(10)(A),β = 111.342(2)°,V = 4629.7(5) (A)3,Dc = 1.470 g/cm3,μ =1.100 mm-1,F(000) = 2104,R = 0.0575 and wR = 0.1282 for 5528 observed reflections (I＞ 2σ(I)).The photoluminescent spectra for this compound have also been studied.     

Synthesis, Crystal Structure and Inhibition of the K562 Cell Proliferation of N＇-Tertbutylaminocarbonyl-N-2-chlorophenoxyacetylthiourea

The title compound N'-tert-butylaminocarbonyl-N-2-chlorophenoxyacetylthiou- rea has been synthesized for the first time. Complete assignments were achieved by IR, 1H NHR and single-crystal X-ray diffraction analyses. The inhibitory rate of the cellular growth of K562 cells (chronic myeloid 1eukemic cells) was measured using MTT [3-(4,5-dimethylthiazo-2-y1)-2,5-di- phenyltetra-zolium bromide] assay. The cell apoptosis was assessed by agarose gel electrophoresis to find that the title compound has antiproliferation and apoptosis inducing effects on K562 cells. In order to investigate the relationship between structure and activity of the target compound, we report its crystal structure and biological behavior in the present paper. Crystallographic data: C14H18- ClN3O3S, Mr = 343.82, orthorhombic, space group Pnma, a = 19.786(6), b = 6.789(2), c = 12.938(4) , V = 1738.0(9) 3, Z = 4, Dc = 1.314 g/cm3, F(000) = 720, μ(MoKα) = 0.354 mm-1, R = 0.0378 and wR = 0.0941. The molecule is a planar structure.     

Influence of Fe2O3 and V2O5 on Crystalline Structure of Mg-Al Spinel Synthesized by Waste Aluminum Slag

Mg-Al spinel is synthesized by using industrial waste-residue and basic magnesium carbonate in the aluminum factory as the main raw materials. The influence of V2O5 and Fe2O3 mineralizers on the structure, cell parameters and microscopic morphology of synthesized Mg-Al spinel has been discussed. The Mg-Al spinel is characterized by using XRD, SEM and relevant analytical software, such as Philips plus, Rietveld quantification and so on. The experimental results show that certain amounts of V2O5 and Fe2O3 are beneficial to the formation of Mg-Al spinel, and the optimum addition of V2O5 and Fe2O3 is respectively 2wt% and 3wt%. V2O5 has few effects on cell parameters of Mg-Al spinel; but Fe2O3 can form solid solution with Mg-Al spinel in which Mg-Fe spinel can also dissolve to form continuous solid solution. Therefore, with the increase of Fe2O3 content, the cell parameters of Mg-Al approximately present linear increase.     

亚里士多德的哲学元素观及其在化学中的演化

亚里士多德早在两千多年前就总结了古希腊自然哲学家们探索世界万物本原的思想成果,提出了与近代表述极其相近的古代元素概念。只是由于长期无人挖掘和论述,以致被埋没和误解。本文探讨了亚里士多德的哲学元素学说(包括元素概念和元素体系两部分内容)及其对近代化学、尤其是对近代化学元素论和原子论建立和发展的影响。指出了亚里士多德元素观中的“不可分性”概念,一直被近代化学元素论所继承和发展,直至现代科学元素学说建立后才被推翻。     

Some intriguing items in the history of scientific balances

The short survey covers the development of the balance since its invention in the Neolithic era. Scales have been used most probably first as tools in trading, but already in Old Egyptian papyrus its use in techniques is documented. Its theory was cleared by Aristotle and Archimedes and at least at that time it was used as a scientific instrument. Today the balance is still the most widely used instrument in science and there are still improvements.     

多环麝香(PCMs)的环境行为及毒性效应

多环麝香(PCMs)作为重要的人工合成麝香广泛应用于日用品中,目前在各种环境介质中都能检测到PCMs的存在。由于其持续不断地进入环境并能够在生物体内积累,其效应类似于持久性污染物。作为一类新型污染物,PCMs所引起的环境问题受到了广泛重视。本文介绍了PCMs的物理化学性质、来源以及在不同环境介质中的分析方法和污染现状,概述了其在环境中的降解转化、生物富集行为,并总结了其能产生的急性毒性效应、亚慢性毒性效应、内分泌干扰效应和其他潜在的毒性效应,最后讨论了目前研究中存在的问题,并对未来研究进行了展望。今后,应该建立有效的、可比对的标准分析方法,更加系统地进行环境污染现状、迁移转化规律和生物降解代谢途径的研究;重视暴露途径和生物有效性的研究,并与风险评价结合;结合环境中PCMs的污染现状,探讨低剂量长期暴露和复合暴露对生物的影响。     

Time and poling history dependent energy storage and discharge behaviors in poly(vinylidene fluoride-<Emphasis Type="Italic">co</Emphasis>-hexafluoropropylene) random copolymers

 We studied cycle time (0.01–10 s with triangular input waves) and poling history (continuous versus fresh poling) dependent electric energy storage and discharge behaviors in poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] films using the electric displacement ― the electric field (D-E) hysteresis loop measurements. Since the permanent dipoles in PVDF are orientational in nature, it is generally considered that both charging and discharging processes should be time and poling history dependent. Intriguingly, our experimental results showed that the charging process depended heavily on the cycle time and the prior poling history, and thus the D-E hysteresis loops had different shapes accordingly. However, the discharged energy density did not change no matter how the D-E loop shape varied due to different measurements. This experimental result could be explained in terms of reversible and irreversible polarizations. The reversible polarization could be charged and discharged fairly quickly (< 5 ms for each process), while the irreversible polarization depended heavily on the poling time and the prior poling history. This study suggests that it is only meaningful to compare the discharged energy density for PVDF and its copolymer films when different cycle times and poling histories are used.     

核电站电缆料的制备技术及研究进展

能源短缺已成为全球性问题,利用核能发电已经成为解决能源短缺的重要途径之一。核电的发展为核电站电缆料带来了广阔的发展空间。积极研究、开发及应用核电站电缆料对于我国的核能利用具有重要意义。本文介绍了核电站电缆料的种类、性能、生产方法和国内外的研究现状,并对核电站电缆料的发展趋势做了展望。     

Pseudo‐R 2’s in the ordinal probit model*

This paper presents an analysis of the combining mechanism for status information postulated by the mathematical formulation of the theory of status characteristics and expectation states. Six lemmas on the basic features of the combining mechanism are derived from the formulation and discussed. Further, four theorems that illustrate the implications of the particular combining mechanism for power and prestige orders are presented and proven.