黄腐酸促进超氧化物歧化酶形成的作用机制探究

本论文利用Discovery Studio 4.5初步探讨了腐植酸中的黄腐酸促进超氧化物歧化酶形成的作用机制。黄腐酸作为一种生物刺激素已被广泛的应用于农业生产,并且很多研究表明,黄腐酸在植物的许多生理过程中起了非常重要的作用。实验数据显示,在一定浓度范围内,黄腐酸对玉米幼苗叶片中超氧化物歧化酶的形成有一定的促进作用。通过分子模拟软件Discovery Studio 4.5对机理的研究表明,这是由于黄腐酸先与植物中的钙调蛋白结合,形成较为稳定的配合物,后再与超氧化物歧化酶作用,降低了酶本身的能量,不仅使其更容易被合成,同时还增加了它与其他物质的亲和力。     

磺化反应对沥青质聚集影响的分子动力学研究

利用Gromacs软件,采用分子动力学模拟方法,以委内瑞拉沥青质为模型,考查了磺化反应对沥青质聚集的影响。分子动力学模拟结果表明,随着沥青质分子中磺酸基数目的增加,分子间的静电作用和范德华作用均增大,分子间的静电作用占总相互作用的比重增大。氢键数目及氢键相互作用大幅度增加,磺化后沥青质更容易发生聚集。     

低溶解度酚醛树脂在水中的分散特性

为了研究低溶解度酚醛树脂在水中的分散特性及分散稳定性,测定了低溶解度酚醛树脂分子聚集体的流体力学直径、Zeta电位及体系的浊度。结果表明:在去离子水中,低溶解度酚醛树脂以分子或聚集度较小的分子聚集体存在,Zeta电位较高,体系浊度较小,体系稳定;加入NaCl时,低溶解度酚醛树脂形成较大的分子聚集体,Zeta电位降低,体系浊度增大,稳定性变差;加入HCl时,低溶解度酚醛树脂分子或聚集体负电荷密度减少,Zeta电位降低,体系稳定性下降;加入NaOH时,低溶解度酚醛树脂分子或聚集体负电荷增加,分子间的静电斥力增强,体系的稳定性增加。     

黄腐酸法处理重金属离子的作用机理研究

<正>从黄腐酸的组成结构和黄腐酸与重金属离子相互作用2个方面简要总结了近年来黄腐酸处理重金属离子作用机理的研究进展。黄腐酸对矿物质和纳米材料吸附重金属离子存在重要影响。文章最后展望了黄腐酸法处理重金属离子污染的研究前景。     

黄腐酸及其金属盐热稳定性研究

引言黄腐酸是腐植酸中分子量较低部分,能溶于酸、碱和水,亦溶于丙酮和乙醇。黄腐酸金属盐对土壤和水域的物理、化学和生物方面的性质影响很大,土壤中黄腐酸与金属离子的相互作用在改良土壤、促进植物生长、防止环境污染等方面起着重要作用。在工业上也用于钻井泥浆。研究黄腐酸金属盐热稳定性是研究它们的结构与性质的一种重要方法。关于腐植酸差热分析曾有一些报导,     

生化黄腐酸的界定及其资源开发利用探讨

用生物技术方法是否可以从植物残体中制取黄腐酸?生化黄腐酸是否存在?它的化学特征和作用机理如何理解?笔者对生物或化学方法制取类似腐植酸的物质已研究多年,本文将阐述生物发酵制取类黄腐酸物质(生化黄腐酸)的界定及其资源开发利用的一些看法。     

哈密黄腐酸副产品（残渣）改土培肥增产效果研究初报

哈密有我国最大的富含黄腐酸的风化煤基地,贮量达3.6亿立方。哈密市黄腐酸厂生产的黄腐酸,含量高,分子置小,易溶于水,活性高,在农业和医疗上的作用已得到科学认定。该厂生产的“FA旱地龙”(高效多功能植物生长调节抗旱营养剂)和精制黄腐酸供不应求,黄腐酸副产品(残渣)也被农民抢购一空,用于农田改土培肥,反映其效果不但有而且好,但只是处于感性认识阶段,缺乏有力地科学试验依据,为了更好地推动残渣的推广利用,由该厂建议哈密市科委下达《哈密黄腐     

沥青质分子聚集行为研究进展

沥青质的聚集与其相行为、流动性、结焦、沉积等密切相关，是影响重油加工的关键。沥青质分子结构的高芳香性、高杂原子含量等特点，使其存在多个易发生分子间相互作用的活性位点，是沥青质发生聚集的主要原因。描述沥青质聚集行为的模型主要有Yen-Mullins模型、超分子组装模型、类线性聚合模型以及溶解度模型等，本文对这些模型进行了详细的介绍，分析了各种模型的特点。文中指出Yen-Mullins模型通过沥青质分子、纳米聚集体、团簇描述了沥青质聚集过程；超分子组装模型基于超分子化学，认为沥青质聚集是多种相互作用累积形成的超分子结构；类线性聚合模型和溶解度模型都是对沥青质聚集行为进行简化，主要用来预测沥青质的分子量和溶解行为。沥青质的分子结构是产生各种相互作用及聚集行为的基础，而现有的分离和表征主要是基于沥青质团聚体，因此高效分离和精确表征得到沥青质单分子结构是研究沥青质分子间相互作用及聚集机理的关键。     

一种驱油用两亲聚合物溶液性能研究

通过激光光散射仪和扫描电镜对两亲聚合物(AP)溶液微观形态进行了研究,结合界面张力仪和流变仪对两亲聚合物性能进行了探讨。结果表明,AP溶液的临界胶束浓度(CMC)为1 000 mg·L~(-1),当AP溶液浓度低于CMC时,溶液中自由链与单分子胶束发生聚集交联,形成具有一定网络结构的单分子胶束聚集体,使AP溶液表现出以弹性为主的特征;当AP溶液浓度高于CMC时,溶液中会形成多分子胶束以及胶束的聚集体,随着AP溶液浓度的增加,多分子胶束和胶束的聚集体交联成了超分子结构的空间网络。AP溶液对油-水界面张力的降低最低可达10mN·m~(-1)左右。     

黄腐酸对菁染料超分子组装及手性调控研究

<正>利用菁染料超分子作分子探针对黄腐酸进行标记,检测黄腐酸和药效机制对生命科学和药物化学领域的发展具有重要意义。采用紫外-可见吸收光谱和圆二色谱研究黄腐酸为模板对不同结构菁染料超分子的组装及手性调控。结果表明:黄腐酸能诱导3种菁染料J-聚集体解聚为单体并     

溴化1-辛基-3-甲基咪唑聚集状态对蛋白质结晶的影响研究

研究了离子液体溴化1-辛基-3-甲基咪唑（［C₈mim］Br）添加剂的聚集状态对蛋白质结晶过程的影响。实验发现［C₈mim］Br可以改善溶菌酶晶体形貌,影响晶体数量和晶体尺寸。通过测定不同浓度［C₈mim］Br下溶菌酶的溶解度、结晶动力学、聚集状态和ζ-电势,揭示了离子液体［C₈mim］Br对溶菌酶结晶的影响机理。结果表明,［C₈mim］Br与溶菌酶的作用方式随［C₈mim］Br的聚集状态而改变。当［C₈mim］Br浓度较低（<0.1 mol/L）时,［C₈mim］⁺与溶菌酶分子之间存在疏水作用,可以促进蛋白质分子聚集,促进结晶过程。当［C₈mim］Br浓度较高（>0.1 mol/L）时,［C₈mim］⁺自发聚集成胶束,并与蛋白质分子相互作用形成溶菌酶-胶束复合物;动态光散射（DLS）结果显示结晶过程以溶菌酶-胶束复合物为基本单元聚集,因此结晶过程减缓,晶体质量提高。     

Investigation on the interaction of collagen molecules in solution with different acetic acid concentrations

Collagen solutions in the presence of 0.1–2.0M acetic acid (AA) were investigated to understand the interaction between collagen molecules and an acidic solvent. Fluorescence measurements of pyrene showed that the critical aggregation concentration (CAC) of collagen increased from 0.518 to 1.581 mg/mL for AA concentrations ranging from 0.1 to 2.0M, indicating that the aggregated state of collagen molecules was associated with AA concentration. The size of the collagen aggregates, determined by dynamic light scattering, demonstrated that their disaggregation was enhanced with increasing electrostatic repulsion between the collagen chains. The variations in the intrinsic viscosity and Huggins coefficient depended on the molecular interaction among the collagen molecules. Furthermore, the increased AA concentration has a different influence on the rigidity of collagen molecules above and below the CAC. This observation was manifested by the changes in the morphology of collagen molecules observed by atomic force microscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45255.     

相反电荷强聚电解质复合物盐溶液的粘度研究

合成了高电荷密度的磺酸基强聚电解质,考察了其与阳离子聚电解质聚二烯丙基二甲基氯化铵（PDADMAC）稀溶液复合体系的流动特性。无论外加盐浓度高低,剪切速率高于10s^-1时,复合体系都表现出牛顿流体的行为。在水溶液中,随PDADMAC的增加,复合体系的增比粘度逐渐减小;在高浓度的NaCl溶液中,随PDADMAC的增加,体系的增比粘度基本保持不变。随体系离子强度增大,复合体系增比粘度出现极大值,反映了复合聚集的加强;继续增大离子强度,则复合解离,增比粘度变小直至恒定。     

Premicelle formation of double-chain surfactants and bile salts in the neighborhood of the CMC region: application of a differential conductivity technique to the determination of micellization parameters

It has been demonstrated that differential conductivity, dκ/dC, is useful for experimentally extracting the contribution of micellar aggregates from the conductivity data of an ionic surfactant solution in which aggregates and monomers coexist. This extraction allows us to treat the micellization process using a simple two-state model (nS→M) instead of the general mass action model of micellization (nS+qG→M). As a result, the three parameters of micellization, i.e., aggregation number (n), micellization constant, and ionization degree (α) of micelles, for homologous double-chain surfactants and bile salt derivatives can be determined. It was found that when the side-chain was long enough, the double-chain surfactants examined formed highly ionized (α=0.6-0.9) and small (ca. n=20) aggregates, regarded as premicelles.     

Investigation on Aggregate Formation of Ionic Liquids

Understanding the behavior of ionic liquids on the molecular level is essential for explaining solubilizing or reaction processes, including catalytic reactions in ionic liquids or with ionic liquids as co‐solvent. Using mass spectrometry techniques it is possible to characterize their aggregate formation behavior, which depends on the used solvent. With increasing polarity of the solvent and decreasing ionic liquid concentration, the size of the formed aggregates decreases. From conductivity measurement curves “critical aggregate concentrations” were calculated, which confirm the results of mass spectrometry measurements. Addition of ionic liquids increases the solubility of acetophenone in water. This effect can be explained by the aggregate formation ability of ionic liquids. The findings can be used to explain the outstanding solubility and solvation properties of ionic liquids.     

稳态荧光探针法测定SDS表面活性剂胶束聚集数

以芘作为荧光探针,十六烷基氯化毗啶（CPC）作为猝灭剂,根据芘的荧光强度之比随表面活性荆水溶液浓度的变化,测定十二烷基硫酸钠（SDS）的裕界胶柬浓度（cmc）,测定值与文献值较一致。并用外推法得到SDS的胶束聚集数（n）。文章提供了一种简单可行的实验方法了来计算和评价胶束的基本特性。     

Insight into nitric acid extraction and aggregation of N,N, N’, N’-Tetraoctyl diglycolamide (TODGA) in organic solutions by molecular dynamics simulation

The molecular dynamics (MD) simulation of TODGA in n-dodecane shows formation of nanostructures of TODGA aggregates with nitric acid and water. These aggregates are dispersed in dodecane phase or form well defined reverse micelles grown sufficient in size depending on the acid concentration. With increasing nitric acid concentration, aggregation number of TODGA in reverse micelles also increases which, however, is independent of TODGA concentration. Aggregation number rises from 2 to 8 in presence of 0–3.5 M nitric acid in corresponding aqueous phase. The formation of the aggregates explains remarkable acid co-extraction from aqueous phase to organic dodecane phase by TODGA.     

缔合型增稠剂的结构、性能及增稠机理研究进展

缔合型增稠剂是一种水溶性聚合物,在临界缔合浓度以上,形成以分子间缔合为主的超分子结构,增大了流体力学体积,因此具有较好的增稠性,是新一代的增稠剂。本文主要介绍了疏水缔合水溶性聚合物的结构及溶液性质,具体讨论了影响疏水缔合水溶性聚合物的增稠性能的多种因素,包括聚合物的结构和组成,分子量,离子基团,温度,剪切速率,表面活性剂。     

水相和特殊介质中有序聚集体的结构、性质和应用（Ⅰ）——表面活性剂在水相和离子液体中的有序聚集体

首先介绍了表面活性剂溶液性质和各种聚集体结构,其中包括胶束、微乳液、囊泡和溶致液晶等,以及聚集规则———临界堆积参数等。同时介绍了表面活性剂在离子液体中形成的各种典型有序聚集结构,特别阐明在室温下表面活性剂在水溶液和离子液体中聚集形成的有序聚集体的异同点;另外还介绍了利用表面活性剂在离子液体中形成的聚集体作为模板制备微纳颗粒。     

Polymorphism of Alpha-Synuclein Amyloid Fibrils Depends on Ionic Strength and Protein Concentration

Protein aggregate formation is linked with multiple amyloidoses, including Alzheimer‘s and Parkinson‘s diseases. Currently, the understanding of such fibrillar structure formation and propagation is still not sufficient, the outcome of which is a lack of potent, anti-amyloid drugs. The environmental conditions used during in vitro protein aggregation assays play an important role in determining both the aggregation kinetic parameters, as well as resulting fibril structure. In the case of alpha-synuclein, ionic strength has been shown as a crucial factor in its amyloid aggregation. In this work, we examine a large sample size of alpha-synuclein aggregation reactions under thirty different ionic strength and protein concentration combinations and determine the resulting fibril structural variations using their dye-binding properties, secondary structure and morphology. We show that both ionic strength and protein concentration determine the structural variability of alpha-synuclein amyloid fibrils and that sometimes even identical conditions can result in up to four distinct types of aggregates.