纳米棒状MAl2O4:Eu2+, Dy3+(M=Sr, Ba)长余辉发光材料的制备与性能

利用硝酸铝、硝酸锶/硝酸钡、尿素为原料,以一定比例H2O/正丁醇/CTAB的混合液作传递压力的介质进行反应,然后将得到的前驱体在还原气氛下高温煅烧,得到亮度高、余辉时间长的MAl2O4∶Eu^2＋,Dy^3＋纳米结构长余辉发光材料。TEM测试表明,高温煅烧后得到的MAl2O4∶Eu^2＋,Dy^3＋均为棒状结构,其激发光谱和发射光谱均为宽带,主发射峰分别为513和498 nm,是典型的Eu^2＋5d→4f跃迁。在对单掺Eu^2＋与双掺Eu^2＋,Dy^3＋比较的过程中,明显发现双掺Eu^2＋和Dy^3＋的强度增加,且余辉增强。材料的余辉强度随时间的变化由最初的快减过程和随后的慢减过程组成,符合I=t^-1.1双曲线规律。该方法操作简单,在不同的温度和时间下均合成出了棒状MAl2O4∶Eu^2＋,Dy^3＋,不需球磨,可直接应用。     

水热法制备ZnS纳米线

以十六烷基三甲基溴化铵(CTAB)为表面活性剂，利用水热法通过二吡啶硫氰酸锌分解制备了ZnS纳米线，并用SEM、XRD、EDX和HR-TEM等方法对其纳米结构进行了表征。实验结果表明，反应时间和表面活性剂浓度是决定纳米ZnS最终形貌的关键因素，CTAB起到了纳米线生长的分子-诱导模板作用。     

介孔碳负载铂催化剂的分散性和电催化活性

以介孔硅SBA-15为模板, 糠醇为碳源制备了高度有序的介孔碳(CMK-5), 并用微波法合成碳负载的铂纳米粒子的催化剂. 为改善铂微粒的分散性能, 在微波碳载过程中添加了适量的阳离子表面活性剂(CTAB). XRD和TEM测试结果表明, CTAB的加入改善了铂催化剂的分散性, 且使铂微粒的平均粒径降至2.9 nm左右. 循环伏安测试结果显示, 加入CTAB后所得Pt/CMK-5催化剂的电化学活性面积大于未加CTAB的以及商业Johnson Matthey公司的Pt/C催化剂的活性面积.     

Novel fluorescent colloids as a DNA fluorescence probe

Fluorescent perylene colloids in the 80–90 nm size range have been prepared by the reprecipitation method. These nanoparticles were modified by cetyltrimethylammonium bromide (CTAB) which inhibited their growth. The nanoparticles also readily interacted with DNA. The fluorescence emission was measured at _ex/_em=400/565 nm. The fluorescence decrease of colloid–CTAB in aqueous solution was measured in the presence of nucleic acids. Under the optimum conditions, the ratio of fluorescence intensity in the absence and presence of nucleic acids was proportional to the concentration of nucleic acids over the range 0.02–5.1 µg mL^–1 for FS (fish sperm) DNA or CT (calf thymus) DNA. The detection limits were 0.01 µg mL^–1 for FS DNA and 0.012 µg mL^–1 for CT DNA, respectively. Based on this approach, a new quantitative method for DNA assay is presented in this paper.     

Electric Spectra Study of Tetra-Hydrophenyl Porphyrin with Two Hexadecyl Chains in CTAB Micelle Aqueous Solutions

Abstract

UV-visible and fluorescence spectral studies shows that tetra-hydrophenyl porphyrin with two hexadecyl chains (P₂) could be solubilized in CTAB micelle, and that the hydrophilic ability of P2 increases with increasing bulk pH. The change in bulk pH lead to the changing of the solubilizing location of P₂ in the CTAB micelle. In neutral (pH 6.88) conditions, the hydrophilic head group of P₂ readily locates in the stern layer of CTAB micelle. However, the solubilizing location of P₂ takes a location change to the outer surface of the CTAB micelle with the bulk pH increasing up to 11.41. Furthermore, the CTAB micelle could provide a strong basic microenvironment (like 1.5 mol dm^?3 NaOH aqueous solution) to P₂ in mild basic conditions; resulting in the deprotonation of the pyrrole nitrogen of the porphyrin moiety in a mile basic CTAB micelle solution.     

Adsorption of Corrosion Inhibitors onto Iron Carbonate (FeCO3) Studied by Zeta Potential Measurements

The adsorption of cetyl trimethyl ammonium bromide (CTAB) and two commercial inhibitor base chemicals, an oleic imidazoline salt (OI) and a phosphate ester (PE), onto iron carbonate (FeCO₃), was studied by zeta potential measurements in a 0.1 wt% sodium chloride (NaCl) solution under 1 bar CO₂ at 22°C, in the absence and presence of a refined low-aromatic oil. The zeta potential of oil-in-water emulsion droplets was also determined. Surface tension of 0.1 wt% and 3 wt% brines was measured as a function of inhibitor concentration. The isoelectric point was pH 6.0 in the 0.1 wt% NaCl solution under 1 bar CO₂. The results show that all three inhibitor compounds adsorbed onto the iron carbonate particles both at pH 4.0 and pH 6.0. Adsorption on both negatively charged surfaces and surfaces with no charge were thus found for all inhibitors. The addition of oil had no significant effect on the measured zeta potential on iron carbonate particles.     

Synergistic adsorption of Triton X-100 and CTAB surfactants at the toluene + water interface

Equilibrium interfacial tension measurements at 25.0 °C of the toluene + water system with two widely used surfactants, octylphenol decaethylene glycol ether (Triton X-100) and cetyl trimethyl ammonium bromide (CTAB) having concentrations much lower than their CMC were performed. According to the obtained parameters from the Szyszkowski equation, Triton has higher adsorption tendency than of CTAB. The results obtained for surfactants mixtures are analyzed by the theory of non-ideal interactions in binary mixtures (NIBMs) and the interfacial composition and the interaction parameter in the mixed adsorbed monolayer are determined. The attractive interaction shows a maximum value at nearly equal surfactants bulk mole fraction. The synergism is achieved for Triton bulk mole fractions of 0.30 and higher, and the highest degree of synergism (40.6%) is found for the bulk mole fraction of 0.52 with the lowest investigated constant interfacial tension of 28.0 mN m⁻¹. A correlation was developed for variation of the interaction parameter with bulk mole fraction.     

Thermodynamic studies of inclusion complex between cetyltrimethylammonium bromide (CTAB) and β -cyclodextrin ( β -CD) in water/n-butanol mixture,using potentiometric technique

The behaviour of the inclusion complex consisting of cetyltrimethylammonium bromide (CTAB) and β-cyclodextrin (β-CD) in water/n-butanol mixture was studied using ion selective electrodes sensitive to surfactant ions. The experiments were carried out at different temperatures and different composition of water/alcohol. The data obtained indicate that the inclusion complexes S(CD) and S(CD)₂ had formed between CTAB and β-CD in water/alcohol mixture environment. In addition to the 1 : 1 complex, CTAB formed 1 : 2 complexes with β-CD. Further investigation showed that K ₁ for S(CD) was greater than K ₂ for S(CD)₂, and the values of K_i were reduced with increasing butanol concentration. Finally, thermodynamic parameters of the complexation, i.e. ΔH°, ΔG° and ΔS° were also calculated. The obtained thermodynamic data showed that the hydrophobic interaction is the main factor for inclusion complex formation and tendency of complex formation has been reduced with increasing of medium hydrophobicity.     

Study of the interaction between polyphenol,quercetin and three micelles with different electric charges in acidic and aqueous media

The interactions between the polyphenol quercetin, Q, with three surfactant aggregates with different electric charges named micelles, were studied in aqueous solutions with pH values 4.7 and 7.0, to determine the following parameters: critical micellar concentration (CMC), micelle size and binding constant of the complex (Q-Micelle) proposing interaction sites for the formation of the complex. The surfactants used were: hexadecyltrimethyl ammonium bromide (cationic surfactant), CTAB, sodium dodecyl sulfate (anionic surfactant), SDS, and triton X-100 (non-ionic surfactant), TX100, used as Q fluorescence promoters to determine the CMC. The CMC values of the above surfactants at pH 4.7 were: 0.80 ± 0.10, 1.39 ± 0.07 and 0.59 ± 0.05 mM respectively, being lower than those reported in the water. With dynamic light scattering measurements, the hydrodynamic diameters of each micelle were calculated resulting in values of: 2.4 ± 0.5, 5.0 ± 1.1 and 8.4 ± 4.3 nm at pH 4.7 and: 2.1 ± 0.4, 4.9 ± 1.1 and 11.5 ± 4.1 nm at pH 7.0 respectively. In addition, the binding constants of the complex (Q-Micelle) with 1:1 stoichiometry were calculated from emission fluorescence data giving Log K values: 2.94 ± 0.02, 2.54 ± 0.02, and 3.63 ± 0.05 M^-1 respectively. Finally, from the experimental data by UV–Vis spectrophotometry, the change in the behavior of the Q spectrum upon the addition of each of the surfactants to the system was analyzed, showing a decrease in absorbance when SDS and TX100 were added in an acidic medium, as a consequence of the photo-instability of the drug, suggesting that Q interacts with the outside of these micelles and is not fully incorporated inside them.