齐墩果酸电致化学发光行为的研究

本文发现了齐墩果酸在中性介质中有较强的电致化学发光行为 ,其电致化学发光强度受电化学参数和发光条件的影响。详细考察了各种影响因素 ,确立了最佳发光条件 ,即 +2 .0V电压 ,1.0mol/LKCl体系 ,H2 O2 浓度为 1.5×10 -3 mol/L。在这个条件下 ,齐墩果酸的电致化学发光强度与它的浓度在 4 .38× 10 7～ 4 .38× 10 -5mol/L范围内呈现良好的线性关系 ,检出限达到 2 .0× 10 -7mol/L ,从而提供了电致化学发光测定齐墩果酸含量的方法。     

齐墩果酸药理作用研究进展

五环三萜类化合物齐墩果酸广泛分布于多种天然植物中,具有多种生物活性。本文综述了近年来对齐墩果酸药理方面的研究进展并对其研究前景进行了展望。     

超声波辅助提取枇杷叶中齐墩果酸工艺研究

以枇杷叶为原料,以齐墩果酸得率为指标,采用超声波辅助提取了枇杷叶中齐墩果酸.分别研究了乙醇浓度、料液比、超声时间、超声温度对齐墩果酸提取率的影响,通过正交实验优化了提取工艺.结果表明,齐墩果酸提取的最佳工艺条件是:乙醇浓度80%、料液比1:14、超声时间30min、超声温度60℃,在最佳条件下,齐墩果酸得率可达0.37...     

HPLC法测定陆英中乌索酸和齐墩果酸含量

用SymmetryC18色谱柱,流动相甲醇 水(88∶12),检测波长220nm,流速0.6mL/min,柱温25℃,测定陆英药材中乌索酸和齐墩果酸含量。试验结果表明:峰面积RSD(相对标准差值)均小于2.5%,乌索酸和齐墩果酸平均回收率分别为98.32%(RSD为2.12%)和97.92%(RSD为1.69%)。本法可同时测定乌索酸和齐墩果酸含量,具有准确、灵敏、数据可靠的优点,可用于陆英药材质量控制。     

电致化学发光法测定血清中多巴胺含量

苝四甲酸(PTCA)纳米棒在过硫酸根(S₂O₈^2-)作为共反应试剂的条件下具有高的电致化学发光(ECL)信号,且多巴胺(DA)可以显著猝灭该体系ECL信号。采用PTCA修饰电极,构建用于灵敏检测DA的ECL传感器。随着DA浓度的增加,PTCA/S₂O₈^2-体系的ECL信号逐渐降低,并且在DA浓度为1 nmol/L～500μmol/L范围内,传感器ECL信号和其浓度对数值呈现良好的线性关系,线性方程为I=-2155.18 lgc_DA+6819.86,线性相关系数为R=0.9991,检出限为0.3 nmol/L。血清样品中DA的加标回收率为97.5%～105.8%。本工作为血清中DA快速、灵敏测定提供了新的思路。     

毛细管电泳-电致化学发光法测定氢溴酸右美沙芬

基于氢溴酸右美沙芬增强联吡啶钌的电致化学发光信号,研究了采用毛细管电泳-电致化学发光法分离检测氢溴酸右美沙芬含量的新方法.利用未涂层石英毛细管44 cm×25 μm;分离缓冲溶液为10 mmo/L磷酸盐缓冲溶液(pH 7.5);分离电压15 kV;检测池中溶液为50 mmo/L磷酸盐缓冲溶液(pH 7.5)和5 mmo/L联吡啶钌.在200 s内可实现氢溴酸右美沙芬的分离检测,其线性范围为1.0×10-7～1.0×10-5mol/L,相关系数为O.999 3,检出下限为1.9×10-8mol/L.本法操作简便快速、灵敏度高、结果准确可靠,可用于氢溴酸右美沙芬口服液中氢溴酸右美沙芬的质量监测.     

齐墩果酸治疗肝脏疾病的研究进展

齐墩果酸(oleanolic acid,OA)属五环三萜类化合物,广泛分布于多种植物中。近年来发现,OA具有保肝、抗炎、抗病毒、降糖、降脂、抗肿瘤、增强免疫力等多种药理作用,是治疗传染性急性黄疸型肝炎、病毒性和慢性迁延性肝炎的有效药物。本文通过查阅近几年国内外文献,就OA治疗肝脏疾病的研究进展进行了系统性的综述,为进一步开发和利用OA治疗肝脏疾病提供了理论基础,对OA作为抗肿瘤研发具有一定参考价值。     

女贞子中齐墩果酸的提取工艺及测定方法研究进展

齐墩果酸是女贞子中的主要有效成分。综述了近年来女贞子中齐墩果酸的提取工艺及测定方法。提取工艺包括溶剂提取法、半仿生提取法、超临界流体萃取法、超声波提取法和大孔树脂吸附法。测定方法包括薄层扫描色谱法、气相色谱法、高效液相色谱法和毛细管胶束电动色谱层析法。     

齐墩果酸C28甲酰胺衍生物的合成及活性研究

设计并合成一系列齐墩果酸衍生物,并对其抗肿瘤活性进行研究.以齐墩果酸为起始原料,通过对C-3,C-28位经过氧化,酯化,取代,酯化反应得到目标产物.结果表明:合成1个新型的齐墩果酸甲酰胺衍生物4,目标化合物结构经MS,1H NMR确证,利用MTT比色法选择高表达人肺癌细胞、人胃癌细胞对目标化合物进行初步的体外抗肿瘤活性...     

Electrogenerated chemiluminescence of ruthenium (II) bipyridyl complex directly immobilized on glassy carbon electrodes

Ru(bpy)₃Cl₂ was used to modify the glass carbon electrodes (GCE) by oxidation and co-deposition on the electrode surface. The modified electrodes were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). About 2.2 × 10⁻⁹ mol Ru(bpy)₃ ²⁺ was immobilized on the GCE surface (ϕ = 4 mm). The modified GC electrodes showed stable electrochemiluminescence with tripropylamine (TPrA) as the co-reactant with a linear range from 10 to 500 μM (R ² = 0.999). Among the 10 amino acids tested, the modified electrode system showed selective response to arginine and lysine, indicating that the molecular structure played an important role as co-reactant. This simple and sensitive electrode modifying method when combined with flow-injection or liquid chromatography systems has the potential for amino acid analyses.     

基于半导体量子点的电致化学发光试剂的研究进展

电致化学发光因为不需要激发光源,没有杂散光的干扰,实验设备简单且具有背景信号低、灵敏度高的优点,近年来在环境监测、食品安全分析、生物传感和成像等领域都引起了科学家们广泛的关注.在电致化学发光技术中,发光试剂无疑是最重要的组成部件.随着纳米科学和技术的迅猛发展,半导体量子点由于尺寸调控带隙、表面易于改性和表面态依赖性的电...     

Extraction Behavior of Am(III) and Eu(III) from Nitric Acid Medium in Tetraoctyldiglycolamide-Bis(2-Ethylhexyl)Phosphoric Acid Solution

The extraction behavior of Am(III) and Eu(III) in a solution of tetra-octyldiglycolamide (TODGA), bis(2-ethylhexyl)phosphoric acid (HDEHP), and n-dodecane (n-DD) was studied to understand the role of TODGA and HDEHP in the combined solvent system. The extraction behavior of these metal ions was compared with those observed in TODGA/n-DD and HDEHP/n-DD. The effect of various parameters such as concentrations of HNO₃, TODGA, and HDEHP on the distribution ratio of Am(III) and Eu(III) was studied. Synergistic extraction of both the metal ions observed at lower acidities (<2.0 M) was attributed to the involvement of TODGA and HDEHP for extraction. However, the extraction of Am(III) and Eu(III) in the combined solvent was comparable with that observed in TODGA at higher acidities. The slope analysis of the extraction data confirmed the involvement of both the extractants at all acidities investigated in the present study.     

铝合金在碱性和中性溶液中电化学行为的研究

通过对铝阳极进行交流阻抗、塔菲尔曲线、析氢速率、开路电压测试,研究了多种铝合金在碱性和中性溶液中的电化学行为。发现Al-Ga-Sn-Mg和Al-Ga-Sn-Zn具有较好的电化学性能。与纯铝相比,在碱性电解液中,Al-Ga-Sn-Mg的开路电位负移70mV,抑制析氢速率为37.5%;在中性电解液中,Al-Ga-Sn-Mg合金的开路电位负移447mV。铝阳极在碱性和中性溶液中的反应机理不同。     

EQCM study of the ECL quenching of the tris(2,2′-bipyridyl)ruthenium(II)/tris-n-propylamine system at a Au electrode in the presence of chloride ions

Significant effect of chloride ions on the electrogenerated chemiluminescence (ECL) behavior of the ruthenium(II)tris(2,2′-bipyridine) (Ru(bpy)₃²⁺)/tri-n-propylamine (TPrA) system at a Au electrode was reported. At low concentrations (e.g., [Cl⁻] < 5 mM), the ECL was enhanced; at relatively high concentrations, however, the ECL intensity decreased with the increase of the [Cl⁻]. At [Cl⁻] = 90 mM, ∼50% and 100% ECL inhibition was observed for the first and the second ECL wave, respectively. The electrogenerated gold-chloride complexes (AuCl₂⁻ and AuCl₄⁻) which were verified using an electrochemical quartz-crystal microbalance (EQCM) method were found to be responsible for the ECL inhibition. This study suggests that care must be taken when a Au working electrode is used for ECL studies in chloride-containing buffer solutions (widely used in DNA probes) and/or with the commonly used chloride-containing reference electrodes since in these cases the ECL behavior may significantly disagree with that obtained using other electrodes and reaction media.     

The Nature of the Internal Acid Solution in Sulfonated Poly(styrene-co-divinylbenzene) Resins

The acidities of a series of fully hydrated sulfonated poly(styrene-co-divinylbenzene) resins with varying levels of sulfonation from 0.80 to 5.25 mequiv g^-1 have been characterized. Enthalpies of neutralization with aqueous NaOH have been measured by titration calorimetry. The degrees of acid dissociation () have been measured using FT-Raman spectroscopy, based on the intensity of the –SO₃ ^- stretching band at 1033 cm^-1. The same measurements have been made on aqueous solutions of p-toluenesulfonic acid (p-TsOH), on the basis that these solutions are analogs of the internal solutions in the hydrated resin gels. For resins with low levels of sulfonation, and therefore relatively dilute internal acid solutions, the internal and the equivalent p-TsOH solutions are similar. However, significant differences are seen in highly sulfonated resins where the internal solution concentration is above 4.0 mol kg^-1. At these concentrations, p-TsOH solutions show essentially complete dissociation and enthalpies of neutralization typical of a strong, fully dissociated acid in aqueous solution. In contrast, the acid groups in hydrated resins are largely undissociated and exhibit numerically higher enthalpies of neutralization, and catalytic activity measurements indicate that these acid groups are stronger than normal. It is proposed that this acidity enhancement is associated with networks of sulfonic acid groups which form in highly sulfonated resins. Although such networks have been previously proposed in dehydrated resins, this paper reports the first evidence for their existence in resins under conditions of full hydration.     

化学发光材料双(2,4,6-三氯苯基)草酸酯的合成

草酸酯是过氧草酸酯类化学发光所必需的一种要素化合物，作者合成了一种能提供高强度化学发光的草酸酯即双（２，４，６ 三氯苯基）草酸酯，并以质谱验证了结构。     

腐蚀环境中纤维增强聚四氟乙烯复合材料的摩擦磨损性能研究

分别研究了不同含量碳纤维(CF)、玻璃纤维(GF)填充聚四氟乙烯（PTFE）复合材料在硫酸溶液中和干摩擦条件下的摩擦学性能,同时考察了PTFE复合材料在酸中的腐蚀行为,探讨了相关机理。结果表明,在酸中GF能够提高PTFE的耐磨性,比CF在提高PTFE耐磨性方面具有更好的优势。就酸溶液中的耐磨性和耐腐蚀性而言,15 %（质量分数,下同）是填料的最佳含量,此时GF和CF填充的PTFE,耐磨性分别较纯PTFE提高了7.7和4.4倍;当填料的含量超过15 %时,复合材料的耐磨性和耐腐蚀性均下降,主要是由于此时犁削和磨粒磨损是PTFE复合材料的主要磨损机制。由于酸溶液的冷却和润滑作用,硫酸溶液中PTFE复合材料的摩擦因数大幅降低,但酸溶液抑制了对磨面上转移膜的形成。     

氟硅酸溶液中氟硅酸及氢氟酸含量的测定

基于生成氟硅酸钾沉淀和该沉淀水解均析出不同量酸，用碱滴定完成氟硅酸及氢氟酸的连续测定。该方法用于生产实践，结果令人满意。