Dynamic surface tension,critical micelle concentration,and activity coefficients of aqueous solutions of nonyl phenol ethoxylates

Dynamic surface tensions, σ(t) for aqueous solutions of nonyl phenol ethoxylates (NPEOs) at the temperature 298.15 K were measured using a Lauda drop volume tensiometer. The non-ionic surfactants analyzed in this work were Tergitol NP-9, NP-35 and NP-40. By using the classical Ward and Torday equation, the diffusion coefficient for each bulk surfactant concentration was calculated. The equilibrium surface tension values were determined by extrapolating the dynamic surface tension to t → ∞ on the σ(t) vs. t^−1/2 curves. These values were used to determine the critical micelle concentrations (CMC) of the surfactant aqueous solutions as well as to calculate the infinite dilution activity coefficient of the surfactant, following a model that combines the Volmer surface equation of state and the Gibbs adsorption equation.     

共振光散射方法研究钙存在下十二烷基苯磺酸钠的聚集行为

利用共振光散射技术在不引入探针的条件下,建立了室温下直接测定十二烷基苯磺酸钠(SDBS)的临界胶束浓度(CMC)的方法.研究发现:在室温下,SDBS水溶液的共振光散射强度(RLS)随SDBS浓度的增加而增强;且当SDBS接近其临界胶束浓度时,RLS强度增强显著,共振光散射峰分别位于330和396 nm.396 nm处的RLS强度与SDBS浓度关系曲线呈S型曲线,本文将曲线突升起点处两条切线的交点对应的SDBS浓度,确定为SDBS的临界胶束浓度(CMC),这与荧光芘探针和电导率等方法测定结果基本一致.并利用此方法分别研究了Ca2+浓度对SDBS及其SDBS-聚乙二醇辛基苯基醚(OP)复配体系聚集行为的影响.结果表明,SDBS与OP以1∶ 3复配时,增强了体系的抗钙能力.     

乙二醇对烷基三甲基溴化铵胶团化行为的影响

利用电导法研究了烷基三甲基溴化铵表面活性剂(CnTAB,n=12,14,16),即十二烷基三甲基溴化铵(DTAB),十四烷基三甲基溴化铵(TTAB)和十六烷基三甲基溴化铵(CTAB),在混合极性溶剂乙二醇/水(体积分数0～40%)中的胶团化行为。考察了温度对胶团形成的影响,应用相分离模型估算了三个表面活性剂的胶团热力学参数。结果表明临界胶团浓度(cmc)和反离子解离度(α)都随乙二醇组分的增加而增大。在乙二醇/水混合溶剂中胶团形成的标准吉布斯自由能相差很小,混合焓都是负值,而混合熵都为正值,说明焓-熵补偿效应在胶团形成中起主导作用。     

镧浸种对辣椒种子抗酸雨胁迫能力的强化作用

为了检测镧浸种对辣椒种子抗酸雨胁迫能力的影响,对来自辣椒种子经镧处理和酸雨胁迫1,3和7 d的幼苗生长状况和活性氧代谢进行了测定。结果显示:经镧溶液浸种后,辣椒种子的抗酸雨能力增强,可抵御中强酸雨(pH 3.5)持续胁迫7 d,表现为胚根长和幼苗鲜重均达到对照水平;相对于酸雨组,镧处理组辣椒幼苗中POD活性提高了5.4%,MDA含量降低了6.9%;酸雨组的POD活性和MDA含量均高于对照,分别提高3.9%和25.5%,说明酸雨引发的POD合成是应急,不能有效地限制MDA的积累;基于镧对照的POD活性比对照高,而MDA含量没有相应的提高,说明镧浸种提高了幼苗中POD活性的本底水平。因此,稀土元素是作物的免疫刺激物,镧浸种属于抗胁迫锻炼。     

N掺杂富含(001)晶面TiO_2纳米片的制备及N掺杂浓度对可见光催化活性的影响(英文)

采用水热法制备了富含(001)晶面的锐钛矿型TiO2纳米片,并通过改变热处理过程中NH3流速制备不同N掺杂浓度的TiO2纳米片.运用X射线衍射、场发射扫描电镜、高分辨率透射电子显微镜、紫外-可见漫反射光谱、X射线光电子能谱和荧光光谱对光催化剂进行了结构和性能表征,并以罗丹明B为目标降解物,考察了N掺杂浓度对TiO2纳米片可见光催化活性的影响.结果表明,NH3流速为40ml/min时制备的N掺杂TiO2纳米片具有最低的光生电子-空穴复合速率,最高的OH产生能力并表现出最高的光催化活性.同时,讨论了N掺杂浓度对TiO纳米片可见光催化活性影响的机理.     

Adsorption separation performance of H2/CH4 on ETS-4 by concentration pulse chromatography

To exploit an effective adsorbent to separate hydrogen and methane, microporous titanium silicate molecular sieve NaETS-4 was synthesized and modified by strontium. The adsorption characteristics and diffusion behaviors of the prepared titanosilicate molecular sieve were studied by concentration pulse chromatography. And the effects of ion-exchange and dehydration temperature on adsorbent structure and gas diffusion were also discussed. The results showed that the thermal stability and Henry＇s Law constants were enhanced and micropore diffusivity decreased after exchanging Na＋ with Sr2＋. With the increase of dehydration temperature, Henry＇s Law constant and micropore diffusivity of CI-I4 decreased in both NaETS-4 and SrETS-4. While for 1-12 in SrETS-4, the increase of Henry＇s Law constant and the decrease of diffusion rate can be attributed to the shrinks of pore diameter resulting from the relocation of Sr2＋. Correspondingly, the kinetic selectivity of H2/CH4 reached 8.91 indicating its potentiality in separating H2 and CH4.     

Efficient and highly selective cyclization induced by Lewis acid to generate 2-hydroxyl-α-cyclogeraniol

A cyclization reaction of the hydroxyl-protected geraniol epoxide induced by the different Lewis acids to generate 2-hydroxyl-α-cyclogeraniol has been explored. Compared with the previous methods, this method enhances the production and selectivity of this reaction without the consumption of a large amount of solvent. Also, the coordination of the metal with two oxygen atoms of hydroxyl groups might be crucial for the reaction is first addressed.     

低温低内应力化学镀镍工艺的研究

化学镀广泛应用于非金属的电镀、电铸前的施加导电层。化学镀沉积层质量与其在零件上的附着力有着密切的关系 ,重视对化学镀沉积层内应力的研究 ,开发一个低温、低内应力的化学镀镍工艺 ,对于化学镀沉积层的推广应用有着十分重要的意义。本文采用正交实验方法对低温、低内应力化学镀镍工艺进行了系统研究 ,开发出了一个低温、低内应力的化学镀镍工艺。在实验过程中发现沉积层内应力同其在零件上的结合力具有密切关系并对其进行了初步探讨。1　实验方法1 1　正交实验根据探索性实验结果分析 ,影响化学镀镍层内应力σ和沉积层速率ｒ的主要因…     

(E)-(5-(4-(二苯基胺)苯乙烯基)二噻吩并[2,3-b∶3′,2′-d]噻吩基)-2-亚甲基丙二腈的聚集态发光现象的研究

本文报道了对一种电子给体-受体化合物(E)-(5-(4-(二苯基胺)苯乙烯基)二噻吩并[2,3-b∶3′,2′-d]噻吩基)-2-亚甲基丙二腈(TPA-DCST)的合成与光谱学行为的研究。化合物TPA-DCST的分子结构中含有强电子给体(三苯胺)与强电子受体(二氰基乙烯)两个部分,并由二噻吩并[2,3-b∶3′,2′-d]噻吩作为共轭桥将电子给体与受体相连接。在合成方面,采用Wittig反应将三苯胺通过双键与二噻吩并[2,3-b∶3′,2′-d]噻吩相连接、醛基化,并与并二腈经Knoevenagel缩合反应合成目标产物。产物通过了核磁氢谱、碳谱、红外以及高分辨率质谱的确认。光谱方面,主要考察了该化合物的吸收与荧光行为。其最大吸收峰位在412nm左右,归属于π-π*跃迁。在非极性溶剂正己烷中表现出来自分子间聚集而形成的聚集态荧光(550nm),并通过了单分子在CTAB胶束([c]=1.02×10-2 mol/L)的发光(460nm)试验得到验证。溶剂效应表明,该化合物没有出现典型的ICT态的发光现象,其原因在于电子给体与受体相连的共轭桥单元,即二噻吩并[2,3-b∶3′,2′-d]噻吩不具有有效的共轭效应。浓度效应与温度效应进一步表明TPA-DCST分子易于产生分子间聚集态的发光。在THF-H_2O二元溶剂体系中呈现典型的聚集诱导(AIE)发光现象,发光峰位为692nm。随着TPA-DCST分子间的聚集程度的增加,聚集态的荧光出现大范围的红移,直至固体发光红移到710nm。TPA-DCST分子的聚集因素可能来自于疏脂作用、偶极-偶极相互作用等。