水热制备中国紫BaCuSi2O6的条件探索及各条件产物分析研究

中国紫BaCuSi₂O₆是中国古代人工颜料硅酸铜钡的一种，是中国古代科技史中独树一帜的文明成果，代表了当时中国的科技水平和科技成就。水热合成法通过高温高压的水蒸气使那些在大气条件下不溶或难溶的物质溶解，并且重结晶来进行无机合成与材料处理，是近年来比较新兴的方法。参考前人研究，采用水热合成法，选择BaCl₂·2H₂O，CuO，Na₂SiO₃·9H₂O为原料，按照目标产物化学计量比称取，调控溶液pH、合成温度和保温时间等影响因素，制备出高纯度的中国紫。产物的物相与纯度使用XRD表征。实验结果表明，当10≤pH≤12时可生成纯度较高的中国紫，160 ℃时生成的中国紫纯度较180 ℃更高，且随着水热时间的延长，中国紫的纯度提高。考虑到绿色安全、能耗低、操作简便等因素，最终得出水热制备中国紫的最佳制备条件是pH 12，温度为160 ℃，保温时间48 h。中间产物BaSi₂O₅和Ba₄Si₆O₁₆的发现，表明在硅酸铜钡晶体的生长过程中Ba与Si先与O以不同形式结合，Cu最后参与构筑硅酸铜钡晶体。该工作提供了一种新方法用于合成纯净中国紫，可用来做文物保护修复材料；同时在中国紫的合成机理研究方面提供依据和线索，对中国古代科技史研究具有促进作用。     

溴甲酚紫分光光度法测定水中的阴离子表面活性剂

在pH=2的酸性条件下,十二烷基苯磺酸钠(SDBS)阴离子表面活性剂能与溴甲酚紫直接缔合,生成浅黄色缔合物;据此建立了测定水中SDBS阴离子表面活性剂的分光光度法.结果表明,生成的浅黄色缔合物的最大吸收波长为436nm,SDBS的表观摩尔吸光系数为1.68×104 L·mol-1·cm-1;SDBS的浓度在0²mg·L-1范围内时遵循比尔定律.该方法可方便地用于测定水样中的痕量阴离子表面活性剂,效果良好.     

The importance of a hot-sequential mechanism in triplet-state formation by charge recombination in reaction centers of bacterial photosynthesis

In photosynthesis, pigment-excitation energies in the antenna system produced by light harvesting are transferred among antenna pigments toward the core antenna, where they are captured by the reaction center and initially fixed in the form of a charge separation. Primary charge separation between an oxidized special pair (P⁺) and a reduced bacteriopheohytin (H⁻) is occasionally intervened by recombination, and a spin-triplet state (³P*) is formed on P in the bacterial reaction center. The ³P* state is harmful to bio-organisms, inducing the formation of the highly damaging singlet oxygen species. Therefore, understanding the ³P*-formation mechanism is important. The ³P* formation is mediated by a state |m〉 of intermediate charge separation between P and the accessory chlorophyll, which is located between P and H. It will be shown theoretically in the present work that at room temperature, not only the mechanism of superexchange by quantum-mechanical virtual mediation at |m〉, but also a hot-sequential mechanism contributes to the mediation. In the latter, although |m〉 is produced as a real state, the final state ³P* is quickly formed during thermalization of phonons in the protein matrix in |m〉. In the former, the final state is formed more quickly before dephasing-thermalization of phonons in |m〉. ³P* is unistep formed from the charge-separated state in the both mechanisms.     

Model for primary electron transfer and coupling of electronic states at reaction centers of purple bacteria

A detailed derivation is presented for relations making it possible to describe the effect of temperature on the halfwidth of the P960 and P870 absorption bands and also on the electron transfer (ET) rate at reaction centers (RCs) of the purple bacteria Rps. viridis and Rb. sphaeroides. Primary electron transfer is considered as a resonant nonradiative transition between P* and P⁺B _L ⁻ states (where P is a special pair, B_L is an additional bacteriochlorophyll in the L branch of the reaction center). It has been shown that the vibrational h_α mode with frequency 130–150 cm⁻¹ controls primary electron transfer. It has been found that the matrix element of the electronic transition between the states P* and P⁺B _L ⁻ is equal to 12.7 ± 0.9 and 12.0 ± 1.2 cm⁻¹ for Rps. viridis and Rb. sphaeroides respectively. The mechanism is discussed for electron transport from P* and B_L and then to bacteriopheophytin H_L. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 294–303, May–June, 2006.     

The spatially resolved characterisation of Egyptian blue, Han blue and Han purple by photo-induced luminescence digital imaging

The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of visible light sources were investigated to test their ability to excite luminescence in the pigments. Light-emitting diodes, which do not emit stray infrared radiation, proved an excellent source for the excitation of luminescence in all three compounds. In general, the use of visible radiation emitters with low emission in the infrared range allowed the presence of the pigments to be determined and their distribution to be spatially resolved. This qualitative imaging technique can be easily applied in situ for a rapid characterisation of materials. The results were compared to those for Egyptian green and for historical and modern blue pigments. Examples of the application of the technique on polychrome works of art are presented.

钠紫青铜NaMo_6O_(17)的热电势研究

报道了在 １０～３００ Ｋ 温度范围内,对准二维电荷密度波导体 Ｎａ Ｍｏ６ Ｏ１７紫青铜热电势的测量结果． 在８０ Ｋ 附近, Ｎａ Ｍｏ６ Ｏ１７ 的热电势发生突变是该物质存在 Ｐｅｉｅｒｌｓ 相变的又一个实验例证． 温度高于８０ Ｋ 时,热电势可以用一个经验公式： Ｓ＝ Ａ Ｔ＋ Ｂ／ Ｔ 来描述;而在温度低于 ３０ Ｋ 时,热电势可以拟合为： Ｓ＝ Ａ Ｔ＋ Ｂ Ｔ３ , 说明总的热电势均存在着来自载流子自身的热扩散和声子对载流子的散射两方面的贡献,但高温区和低温区声子对载流子的散射机制是不一样的． 总的热电势值揭示,无论 Ｐｅｉｅｒｌｓ 相变前后,主要载流子均是电子． 上述这些实验结果与 Ｋ Ｍｏ６ Ｏ１７的实验结果比较,有助于进一步加深对紫青铜结构、 Ｐｅｉｅｒｌｓ 相变等物理性质的理解     

Towards a semiquantitative non invasive characterisation of Tyrian purple dye composition: Convergence of UV–Visible reflectance spectroscopy and fast-high temperature-high performance liquid chromatography with photodiode array detection

In this paper, partial least square (PLS) regression is innovatively applied for a semi-quantitative non invasive study of the most precious dye of Antiquity: Tyrian purple. This original approach for the study of organic dyes in the cultural heritage field, is based on the correlation of spectrophotometric (UV–Visible) and chromatographic (Fast-HT-HPLC-PDA) data from an extensive set of textiles prepared with different snail species according to historical recipes. A cross-validated PLS model, based on the quantity of 6,6′-dibromoindigotin, displays an excellent correlation factor (R²Y = 0.987) between values determined by chromatography and those predicted from reflectance spectra. This indicates that the spectral features of Tyrian purple on textile fibre is strictly related to the amount of this indigoid component whose content may be non invasively predicted from reflectance spectrum. The studied correlation also highlights that, independently of the dyeing method and nature of the textile fibre used, the relative content of 6,6′-dibromindigotin may be used as a parameter to distinguish samples prepared with Hexaplex trunculus L. snails from those prepared with further mollusc species. To validate this model, archaeological textile fragments dating from the Roman period were successfully examined. The results achieved open an absolutely new way in Tyrian purple analysis in cultural heritage by non invasive spectroscopic techniques attesting their convergence with HPLC and giving them a semi-quantitative value.     

催化褪色光度法测定痕量钴

钴是人体健康不可缺少的微量元素，本文用酸碱指示剂间甲酚紫作为指示物质，催化动力学测定结果显示间甲酚紫在pH：10．0的NH3-NH4Cl缓冲溶液中呈紫色。Co(Ⅱ)对H2O2氧化这种紫色溶液褪色反应有催化作用，从而建立了测定钴的方法。该法可直接用于维生素B12和生物样品及地下水中Co(Ⅱ)含量的测定。     

Photocycle of 13-cis-retinal in bacteriorhodopsin caused by destruction to the cooperative effect of purple membrane

The steady absorption and kinetic changes of M₄₁₂ intermediate of the light- and dark-adapted bacteriorhodopsin (BR) solubilized by different concentrated Triton X-100 were investigated. The results indicated that the cooperative effect existing within the trimeric BR of native purple membrane (PM) was damaged in the system containing the surfactant since the component and structure of the bilayer lipid membrane in PM varied due to the solubilization of partial PM lipids by Triton X-100. The destruction to the cooperative effect of BR ultimately caused 13-cis-retinal of the dark-adapted BR to take part in BR photocycle and also to generate the deprotonated M₄₁₂ intermediate. Project supported by the key and major projects from the Chinese Academy of Sciences (Grant Nos. Kj951-A1-501-05 and Kj952-S1-03)     

Photocycle of 13-cis-retinal in bacteriorhodopsin caused by destruction to the cooperative effect of purple membrane

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