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     

Caffeoylquinic Acid Derivatives of Purple Sweet Potato as Modulators of Mitochondrial Function in Mouse Primary Hepatocytes

Owing to their antioxidant properties, caffeoylquinic acid (CQA)-derivatives could potentially improve the impaired metabolism in hepatic cells, however, their effect on mitochondrial function has not been demonstrated yet. Here, we evaluated the impact of three CQA-derivatives extracted from purple sweet potato, namely 5-CQA, 3,4- and 4,5-diCQA, on mitochondrial activity in primary hepatocytes using an extracellular flux analyzer. Notably, an increase of maximal respiration and spare respiratory capacity were observed when 5-CQA and 3,4-diCQA were added to the system indicating the improved mitochondrial function. Moreover, 3,4-diCQA was shown to considerably increase glycolytic reserve which is a measure of cell capability to respond to an energy demand through glycolysis. Conversely, 4,5-diCQA did not modify mitochondrial activity but increased glycolysis at low concentration in primary hepatocytes. All compounds tested improved cellular capacity to oxidize fatty acids. Overall, our results demonstrated the potential of test CQA-derivatives to modify mitochondrial function in hepatic cells. It is especially relevant in case of dysfunctional mitochondria in hepatocytes linked to hepatic steatosis during obesity, diabetes, and metabolic syndrome.     

蜀葵花紫色素的提取及其稳定性研究

从蜀葵花瓣中提取的紫色素是一种安全无害的天然染料,本文对蜀葵花中的紫色素的提取及稳定性的研究作了介绍。     

Two orientations and photochromism of polyelectrolyte/bacteriorhodopsin alternative deposition multilayers

A series of organized multilayers have been formed by the alternative adsorption of positively charged poly(dimethyldiallylammonium chloride) (PDAC) and purple membrane (PM) fragments in suspensions at pH = 4—11. Both UV-vis spectrophotometry and quartz crystal micro-balance (QCM) technique were used to monitor the deposition process of PDAC/bacteriorhodopsin (bR) multilayers, suggesting that PM fragments and PDAC are deposited alternatively on the substrate uniformly. Upon illumination, all these multilayers generate photovoltages with defined signs. The negative sign of photovoltage accompanying the formation of M-state at pH <7 indicates that the extracellular side of PM fragments is directed toward the substrate; and the positive sign at pH≥7 indicates that the cytoplasmic side of PM fragments is directed toward the substrate. In addition, the long-lived multiple M-state has been observed in all multilayer films. Moreover, M-state at high pH, which shows the longer lifetime than that at low pH, de     

Assembly of (l+d)-Tryptophan Derivatives Containing an Imidazole Group Selectively Forms a Rare Purple Ni2+-Hydrogel

Design of metal-selective hydrogels is attractive due to potential applications in materials and biological sciences. Although much progress has been made, assembly of both l - and d -amino acid derivatives was less explored for design of metallohydrogels. In this study, we synthesized a facile and small tryptophan derivative containing an imidazole ligand with both l - and d - configurations (denoted as l/d -ImW). Intriguingly, the assembly of (l+d) -ImW gelators was found to selectively form a Ni²⁺-hydrogel in aqueous medium at room temperature, which shows a rare purple color and exhibits excellent multi-responsiveness. In addition to insights into the gelation mechanism, this study provides a novel approach to the design of metallohydrogels, by the assembly of (l+d) -amino acid derivatives containing both aromatic rings and multiple metal coordination sites.     

双波长双指示剂催化动力学光度法测定食品中的痕量铜

在pH=9.65的NH3-NH4Cl缓冲溶液中,利用Cu2+对H2O2氧化中性红和溴甲酚紫褪色反应具有较强的催化作用,通过测量460nm和590nm波长下催化体系和非催化体系的吸光度,建立了双指示剂、双波长催化动力学光度法测定痕量Cu2+的新方法。方法的线性范围为0.0060～0.072μg/mL,检出限为8.0×10-12g/mL。对Cu2+进行11次平行测定的相对标准偏差为2.9%。方法用于面粉和大米中痕量铜的测定,结果令人满意。     

High Sensitivity and Reproducibility of a Bismuth/Poly(bromocresol purple) Film Modified Glassy Carbon Electrode for Determination of Trace Amount of Cadmium by Differential Pulse Anodic Stripping Voltammetry

This work described a novel type of bismuth/poly(bromocresol purple) film modified glassy carbon electrode (denoted as Bi/Poly(BCP)/GCE) for anodic stripping analysis of trace Cd²⁺. The Bi/Poly(BCP)/GCE was fabricated in situ by depositing simultaneously bismuth and cadmium by reduction at ?1.20 V on the poly(BCP) film using a differential pulse voltammetry. Under the optimum conditions, the anodic stripping peak current response increased linearly with the Cd²⁺ concentrations in a range of 2.0×10^?8–1.0×10^?7 M and 1.0×10^?7–6.0×10^?6 M in 0.1 M NaAc‐HAc buffer solution (pH 5.0) with the detection limit of 6.5×10^?9 M (S/N=3). The Bi/poly(BCP)/GCE performed good reproducibility and high sensitivity. Finally, this proposed method was successfully applied to determine the concentration of Cd²⁺ in water samples.     

Spectrophotometric determination of diphenhydramine hydrochloride in pharmaceutical preparations and biological fluids via ion-pair formation

A simple, sensitive and accurate spectrophotometric method has been described for the assay of diphenhydramine hydrochloride (DPH) in raw material and in biological samples. The method is based on extraction of DPH into dichloromethane as ion-pair complexes with patent blue (PB), eriochrome black T (EBT), methyl orange (MO) and bromocresol purple (BCP) in acidic medium. The coloured species exhibited absorption maxima at 632, 514, 428 and 414 nm for PB, EBT, MO and BCP, with molar absorptivity values of 1.32 × 10⁵, 2.36 × 10⁴, 3.68 × 10⁴ and 3.07 × 10⁴ l mol^?1 cm^?1, respectively. The reaction conditions were optimized to obtain the maximum colour intensity. Beer’s law was obeyed with a good correlation coefficient (0.9982–0.9993) in the concentration ranges 0.5–3, 2.0–16, 2.0–10 and 1.0–10 μg ml^?1 for PB, EBT, MO and BCP methods, respectively. The composition ratio of the ion-association complexes was found to be 1:1 in all cases as established by Job’s method. The conditional stability constant (K_f) and the free energy changes (ΔG°) were determined for all complexes formed. The proposed method was successfully applied for the determination of DPH in tablets and human urine with good accuracy and precision. Statistical comparison of the results with those obtained by the official method showed good agreement and indicated no significant difference in accuracy and precision.     

Surface‐enhanced Raman spectroscopy (SERS) on silver colloids for the identification of ancient textile dyes: Tyrian purple and madder

Surface‐enhanced Raman spectroscopy (SERS) was used for the identification of natural organic dyes belonging to indigoid and anthraquinone classes in archeological samples, and good agreement with the corresponding reference commercial materials was found. Special attention was paid to the well‐known problem of anomalous bands that arise sometimes in the SERS spectra on colloids: as suggested in the literature, this problem could be reduced by the use of poly‐L ‐lysine and ascorbic acid as aggregating agents, but we observed that also the addition first of the analyte and subsequently of suitable electrolytes to the colloid in an inverted order compared to the most widely used method can be of help in limiting the intensity of such spurious bands. This procedure allowed us to obtain, for the first time, the SERS spectra of both modern and ancient Tyrian purple and to solve a specific problem observed in the analysis of archeological wool samples dyed with madder lake, i.e. the competition in the SERS response between the dye and other compounds possibly deriving from the degradation of the peptide chain during the hydrolysis treatment during the extraction of the dye from the wool fiber. Copyright © 2009 John Wiley & Sons, Ltd.     

Stereoselective Synthesis of Ferrocenylamino Acids

Enantiopure ferrocenyl-β, and bis-β-amino acids [(R)-(+)-1 and (R, R)-(+)-2] were prepared from (S)-(+)-sulfinimine (3) and (S, S)-(+)-bis-sulfinimine (4) respectively. The desired sulfinimines [(S)-(+)-3 and (S, S)-(+)-4] were prepared from (S)-Andersen reagent (5) and ferrocenecarboxaldehyde (6) and 1, 1 -ferrocenedicarboxaldehyde (7).