Phase Diagram,Electrical Conductivity,and Viscosity Study of Alpha-Sulfonated Methyl Esters Derived from Palm Stearin/1-Pentanol/Hydrocarbon/Water Systems

Microemulsion region of sodium salt alpha-sulfonated methyl ester derived from palm stearin (α-SMEPS)/1-pentanol/alkane/water systems was constructed and investigated at 30.0 ± 0.1°C. The water-in-oil (w/o) microemulsion, bicontinuous structure, and oil-in-water (o/w) microemulsion regions were determined by both conductivity and viscosity methods. Results showed that the microemulsion region decreases and moved towards (α-SMEPS f 1-pentanol) rich corner with the increase in hydrocarbon chain length of alkane from C8 to C16. The changes in alkane chain length from C16 to C8 were found to have shifted the o/w microemulsion f bicontinuous structure f w/o microemulsion transitions of α-SMEPS self-assembly to the rich water corner.     

单磺化酞菁镓在水、微乳液中的解聚反应动力学研究

本文研究了单磺化酞菁镓（ＳＰｃＧａ）在水、微乳液（ＴｒｉｔｏｎＸ－１００－壬烷－正戊醇－水）中的二聚现象和解聚反应动力学，测定了二聚平衡常数ＫＤ和解聚速率常数ｋ。结果表明：ＳＰｃＧａ的解聚反应速率与ＳＰｃＧａ的单体浓度ＣＭ和双体浓度ＣＤ的关系为：Ｖ＝ｋ１ＣＤ－ｋ２ＣＭ２     

某些有机物在溴化银重结晶过程中的作用

卤化银晶体的习性对乳剂的照相性能起决定性作用。因此多年来人们对影响卤化银晶体物理成熟过程的各种因素进行了研究。     

Studies on the phase behavior and solubilization of the microemulsion formed by surfactant-like ionic liquids with ɛ–β-fish-like phase diagram

The phase behavior and the solubilization of the microemulsion systems surfactant-like ionic liquids 1-hexadecyl-3-methylimidazolium bromide (C₁₆mimBr), 1-tetradecyl-3-methylimidazolium bromide (C₁₄mimBr), or 1-dodecyl-3-methylimidazolium bromide (C₁₂mimBr)/alcohol/alkane/brine have been studied with ɛ–β-fish-like phase diagram method at 40 °C and an oil-to-water mass ratio of 1:1. From the ɛ–β-fish-like phase diagram, the physicochemical parameters, such as the mass fraction of alcohol in the hydrophile–lipophile-balanced interfacial layer (A ^S), and the solubilities of ionic liquid (S ^O) and alcohol (A ^O) in alkane phase, were calculated. The solubilization of the microemulsion system has been discussed based on the ɛ–β-fish-like phase diagram. The smaller the oil molecule, the longer the alcohol chain length, and the larger the NaCl concentration in water, the larger the solubilization of the microemulsion system. In this paper, the solubilization of the microemulsion stabilized by both C₁₂mimBr and sodium dodecyl sulfonate (sodium dodecyl sulfate) was also investigated with the ɛ–β-fish-like phase diagram. The unequimolar composite of anionic and cationic surfactants can avoid the sedimentation aroused by the strong electrostatic attraction, and an obvious synergism effect in solubilization was obtained.     

Characterization of RF Discharge in Liquid n-Hexane and its Application to Synthesize Carbon Nano-Particles

The RF plasma discharge in liquid n-hexane is used to synthesize carbon nanoparticles. The results show that amorphous carbon nanoparticles with size of 5?C25?nm are the main product in the plasma in liquid n-hexane. Carbon nano-tubes of average diameter of 19?nm and length of 500?nm are also observed. The energy efficiency for carbon nanoparticles production is 2.9?mg/kJ which is more than 10 times larger than that of typical arc discharge synthesis method. The high speed observation indicates that the RF plasma in liquid has an alternating behaviour and it does not continuously emit light. The OES results show that H and C₂ are the main observed species in the plasma. Based on the OES data, it is shown that plasma temperature is 4,030?K and the electron density is 2.54?×?10²²?m^?3. Our results suggest that this method can be considered as a new route for carbon nanostructures production.     

Observation of two diffusive relaxation modes in microemulsions by dynamic light scattering

Water-in-oil microemulsions stabilized by AOT and dispersed in n-alkane oils with a constant molar water-to-surfactant ratio were studied by dynamic light scattering. A dilution series (in the range of volume fraction of water plus surfactant, phi approximately 0.02-0.52) was used, which allowed us to extract information about droplet sizes, diffusion coefficients, interactions, and polydispersity from experimental data. We report the observation of two diffusive relaxation modes in a concentrated microemulsion (0.20 < phi < 0.5) due to density (collective diffusion) and concentration or polydispersity (self-diffusion) fluctuations. Below this concentration it was difficult to resolve two exponentials unambiguously, and in this case one apparent relaxation mode was observed. It was found that for a given composition self-diffusion is more pronounced in apparent relaxation mode for a shorter chain length alkane. The concentration dependence of these diffusion coefficients reflects the effect of hard sphere and the supplementary attractive interactions. It was observed that the attractive part becomes more pronounced in the case of a large alkane chain oil at a given temperature. This explains the shift of the region of microemulsion stability to lower temperatures for higher chain length alkanes. Increase in hydrodynamic radius, Rh, obtained from the diffusion coefficient extrapolated to infinite dilution was observed with increase of alkane chain length. The polydispersity in microemulsion systems is dynamic in origin. Results indicate that the time scale for local polydispersity fluctuations is at least 3 orders of magnitude longer than the estimated time between droplet collisions.     

Scission Efficiencies of Short Chain Branches in the γ-Radiolysis of Ethylene-α-Olefin Copolymers

Abstract

γ-Irradiation of copolymers of ethylene with propene, 1-butene, and 1-hexene, containing from 1 to 6 alkyl short chain branches per 1000 carbon atoms, at 25°C in vacuum, produced small amounts of n-alkanes with a maximum yield for the alkane corresponding to the alkyl branch of the α-olefin unit. A multilinear regression analysis showed a highly significant dependence of G(C_n alkane) on the frequency of alkyl branches containing n carbon atoms, determined by ¹³C-NMR. The corrections to the G(C_n alkane) yields from other fragmentation processes were substantial but no dependence for G(C_n alkane) on fragmentation of chain ends or fragmentation of the chain following branch elimination could be deduced from the data. The scission efficiencies = G(alkane) divided by the branch frequency per 1000 carbon atoms ± 95% confidence limits were (0.7 ± 0.7) × 10^?3, (2.7 ± 0.8) × 10^?3, and (1.5 ± 0.3) × 10^?3, for methyl, ethyl, and butyl branches, respectively. These factors can be used to determine the short-chain branch frequencies in similar polymers from n-alkane yields on γ-irradiation.     

THE FLOCCULATION OF AQUEOUS SUSPENSIONS OF TITANIA INDUCED BY SURFACE NUCLEATION OF CALCIUM PHOSPHATES#

ABSTRACT

Titanium oxide aqueous suspensions have been destabilized by a novel mechanism; the nucleation of octacalcium phosphate on the particle surfaces, using the constant composition technique. The results suggest that the potential energies resulting from the electric double layers around the titania particles play only secondary roles in the flocculation, in that a decrease in ζ-potential of titania colloids from ?47 mV to ?13 mV does not in itself cause the titania suipension to flocculate, in contrast to the predictions of the classical DLVO theory. However, in the process of hucleation of the moderately hydrophobic octacalcium phosphate phase (γ^- _sequals;19.7 mJ m^-2) onto titania particle surfaces, the latter become more hydrophobic with values ranging from 52 to 23.4 mJ m-2, This change is sufficient to cause the particles to flocculate since the energies of attraction result from hydrophobic interactions (90%) and van der Waals forces (10%).     

Fragment ion formation from n-alkanes and cycloalkanes by plasma desorption

The plasma desorption of hydrogen loss fragment ions from frozen films of several classes of aliphatic volatile hydrocarbons was investigated with ²⁵²Cf plasma desorption mass spectrometry. A time-of-flight instrument suitable for the reproducible sampling and analysis of volatile hydrocarbons in the solid state was designed for this study. Representative compounds from the n-alkanes and cycloalkanes were analyzed. For all the compounds studied, radical molecular ions. M^+., and hydrogen loss fragment ions, [M ? mH]⁺ with m varying from 1 to 10, were produced. The length of the alkane chain, the size of the alkane rings and the stability of the resulting H-loss ions affected the number and abundance of these ions. Smaller molecules underwent proportionally more hydrogen loss than larger molecules of the same class.     

DNA-interaction studies of a copper(II) complex containing ceftobiprole drug using molecular modeling and multispectroscopic methods

Abstract

The interaction of the [Cu(cef)(phen)Cl₂] complex with calf-thymus DNA (ct-DNA) at physiological pH was investigated by UV-visible spectrophotometry, fluorescence measurement, dynamic viscosity measurements, circular dichroism spectroscopy, and molecular modeling. UV-vis spectra showed 5?nm bathochromic shift of the absorption band at 270?nm along with significant hypochromicity for the absorption band of the complex. The binding constant obtained of UV-vis (1?×?10⁵ M^?1) is more in keeping with intercalators and suggests this binding mode. Moreover, thermodynamic parameters indicated that hydrogen bond and van der Waals interactions play main roles in the binding of [Cu(cef)(phen)Cl₂] to ct-DNA. In addition, [Cu(cef)(phen)Cl₂]-DNA docked model is in approximate correlation with the experimental results.     

Preparation of a fluorescent sensor based on BODIPY-functionalized hydroxyapatite nanoparticles and spectroscopic study of the Cd2+ and Zn2+ complex formation

A new fluorescent chemosensor 1, which based on hydroxyapatite (HA) nanoparticles covalently functionalized with a difluoroboron dipyrromethene, has been prepared by nucleophilic substitution of the fluorescent dye 3-chloro-4,4-difluoro-8-(4-tolyl)-5-[bis(pyridine2-ylmethyl)amino]-4-bora-3a,4a-diaza-s-indacene (2) with surface-modified HA nanoparticles. The HA particles were prepared by using SiO₂ as templates (THA) with 3-(aminopropyl)triethoxysilane (THA-APTES). Substitution of the electron-withdrawing chlorine in 2 by an electron-donating amino group of HA changes the properties of the nanoparticles 1 and the corresponding fluorescent dye 2. Absorption and emission maxima of 1 in ethanol are red-shifted by 75 and 30?nm, respectively, in comparison with those of 2. In contrast to no selectivity of dye 2 for Cd²⁺ or Zn²⁺ in EtOH/H₂O (95/5?V/V) solutions, the nanofluorescent probe 1 forms 1?:?1 complexes with Cd²⁺ or Zn²⁺, producing an instant color change along with large hypsochromic shifts in the absorption and fluorescence spectra by 70 and 35?nm, respectively, and large cation-induced fluorescence amplifications.     

Compositions and Physicochemical Properties of Tween Type Surfactants-Based Microemulsions

The compositions and physicochemical properties of the microemulsion systems consisting of Tween type surfactant (Tween 20, Tween 60, Tween 80)/butan-1-ol/dodecane/brine have been studied using ?-β fishlike phase diagram. From the ?-β fishlike phase diagram, solubility of the alcohol, composition of the interfacial layer, and solubilization ability of the microemulsion systems have been studied. The solubilization parameters of the microemulsion systems, SP* were in the order of magnitude Tween 60>Tween 80>Tween 20. The effects of different oils, alcohols, salinities and temperatures on the compositions and physicochemical properties have been investigated. The solubilization ability of the microemulsion systems increases with increasing salinities or decreasing temperatures. The effects of alcohols and alkanes display opposite patterns of change. By increasing the carbon chain length of the alkanol molecules, or decreasing the carbon chain length of the alkane molecules, the solubilization ability increases.     

Mechanism of halide conversion process of colloidal AgCl microcrystals by Br ions : I. Observation of the dynamic changes in shape, structure, and composition

The mechanism of the halide conversion process in suspension of AgCl microcrystals by bromide ions was studied by electron microscopy, X-ray diffractometry, and electron-beam diffractometry. The typical conversion process after the introduction of Br⁻ was found to consist of more than three distinctive steps. The first step was an almost instantaneous reaction within a few seconds for a surface conversion without apparent morphological change of the original particles. The second step was a very rapid epitaxial growth process of virtually pure AgBr crystals on every corner and partly on the edges of the AgCl cubic microcrystals with dissolution of their own {100} faces, which was finished in about 1 min at 25°C. The third step was a much slower process of about 2 h at 25°C (ca. 5 min at 45°C) for the formation of an AgCl_0.5Br_0.5 solid solution developing from the joints of AgBr guest and AgCl host by simultaneous dissolution of the guests and the hosts. After the complete dissolution of the AgBr guests, a further recrystallization process that formed a solid solution richer in chloride content followed. Finally, the conversion virtually stopped midway to yield double-structured particles of Ag(Cl, Br) shell/AgCl core. However, when the initial molar ratio of [Br⁻]₀/[AgCl]₀ was so high as to exceed unity, the original AgCl particles were totally decomposed into about eightfold AgBr particles in number. In this case the steps later than the second one were missing. Also, it was suggested from the subsidiary study on open systems, where bromide ions were added continuously, that the kinetics was basically controlled by the deposition rate of the solute of the AgBr component of the growing parts, though it was switched to being limited by the dissolution rate of the host AgCl crystals when their open surface area for dissolution was extremely diminished.     

PRIMARY INTERMEDIATES IN THE PULSED IRRADIATION OF RETINOIDS

Abstract Laser flash photolysis and pulse radiolysis have led to the characterisation of several shortlived intermediates formed after irradiation of retinoic acid and retinyl acetate in hexane or methanol. For retinoic acid, the triplet state, wavelength maximum 440 nm, extinction coefficient 7.3 × 10⁴ dm³ mol^?1 cm^?1, decay constant 6.2 × 10⁵ s^?1, is formed with a quantum yield of 0.012 for 347 nm excitation. The radical cation, absorption maximum 590 nm, extinction coefficient ～7 × 10⁴ dm³mol^?1 cm^?1, is formed in a biphotonic process. The radical anion, absorption maximum 510nm in hexane, 480 nm in methanol where its extinction coefficient is 1.2 × 10⁵ dm³mol^?1 cm^?1, appears to decay partially in methanol into another longer-lived neutral radical, wavelength maximum 420 nm, by loss of OH^?. For retinyl acetate, the triplet state, absorption maximum 395 nm, extinction coefficient 7.9 × 10⁴dm³mol^?1 cm^?1, decay constant 1.2 × 10⁶s^?1 is formed with a quantum yield of 0.025 for 347 nm excitation. Monophotonic photoelimination of OCOCH₃? in methanol produces the retinylic carbenium ion, wavelength maximum 590 nm, whose decay is enhanced by ammonia, k ～ 2 × 10⁶ dm³ mol^?1 s^?1 and retarded by water. The radical cation also has a wavelength maximum at 590 nm, its extinction coefficient being ～ 1.0 × 10⁵ dm³mol¹ cm^?1. The long-lived transient absorption with maximum at 385 nm, extinction coefficient 1.0 × 10⁵ dm³mol^?1 cm^?1, obtained from the reaction of the solvated electron with retinyl acetate in methanol may be due to either the radical anion itself or more likely the radical resulting from elimination of OCOCH₃? from this anion. These results suggest that skin photosensitivity caused by retinyl acetate might be greater than that due to retinoic acid.     

A PREVIOUSLY UNREPORTED INTENSE ABSORPTION BAND AND THE pK, OF PROTONATED TRIPLET METHYLENE BLUE

Abstract— Excitation by a Q-switched giant ruby laser (1.2 J output at 694 nm ?50 ns flash) of 2–10 µM solutions of methylene blue in water, 30% ethanol in water or 50 v/v% water-CH₃CN at pH values in the range 2.0–9.3 converted the dye essentially completely to its T₁ state. The absorption spectrum of T₁ dye was measured in different media at pH 2.0 and 8.2 by kinetic spectrophotometry. Previously reported T-T absorption in the violet in acidic and alkaline solutions and in the near infrared in alkaline solution was confirmed. Values found for these absorptions in the present work with 30% ethanol in water as solvent are λ_max - 370nm, ε_max, - 13,200 M^-1 cm^-1 at pH 2 and λ_max,?420nm, ε_max 9000 M^-1 cm^-1, λ_max, - 840 nm, ε_max - 20,000 m ^-1 cm^-1 at pH 8.2. Long-wavelength T-T absorption in acidic solution is reported here for the first time: λ_max, ? 680 nm, e_max? 19,000 M cm^-1 in 30% ethanol in water at pH 2. Observation of a pH-independent isobestic point ? 720 nm confirms that the long-wavelength absorptions are due to different protonated states of the same species, MB⁺(T₁) and MBH²⁺(T₁). The pK_a of MBH²⁺(T₁) in water was determined from the dependence on pH of absorption at 700 and 825 nm to be 7.1₄± 0.1 and from the kinetics of decay of triplet absorption to be 7.2. The specific rate of protonation of MB⁺(T₁) by H₂PO₄ in water at pH 4.4 was found to be 4.5 ± 0.4 times 10⁸M^-1s^-1.     

Synthesis of Barium Sulfate Nanoparticles in Water-in-Oil Microemulsion Systems

Micellar solutions of poly(ethylene glycol) octylphenyl ether and n-hexyl alcohol in cyclohexane were used to study the formation of water-in-oil microemulsion system and to synthesize barium sulfate nanoparticles. Barium sulfate particles (the average diameter is 10 nm) were obtained by mixing two microemulsion systems containing Ba²⁺and SO^2– ₄ions. It was shown that the sizes of BaSO₄particles measured by the dynamic light scattering and electron microscopy are in good agreement with each other.     

微乳液聚合制备聚 N-异丙基丙烯酰胺温敏超细微粒

通过微乳液聚合制备了未交联及交联的聚N 异丙基丙烯酰胺 (L PNIPAM及CL PNIPAM)超细微粒 .CL PNIPAM的聚合动力学方程为 :Rp=k[M]1 1 6 [E]- 1 2 0 [I]0 5 3.测得其平均微粒粒径约 10 0nm .用SEM ,迎头色谱法测得交联的CL PNIPAM超细微粒的内比表面积为 49 0 48m2 g ,孔径大小为 1～ 10nm .气体吸附量为1784 8cm3 g .用浊度法及目视法研究了其在水介质中的温敏特性 ,测得其相变温度为 31 5℃     

室温交联型硅丙微胶乳的合成研究II.改性微胶乳的粒径控制及其微观形态表征

采用种子微乳液聚合法和单体预乳化法分别合成了室温交联型有机硅改性聚丙烯酸酯微胶乳,研究了硅烷单体的添加和氨化反应对改性微胶乳粒子大小及分布的影响。结果表明:采用种子微乳液聚合法得到的硅丙微胶乳粒子大小与硅烷单体的种类、用量和添加顺序无关,平均粒径约为40~60nm。TEM照片显示出,采用种子微乳液聚合法合成的硅丙微胶乳粒子由于内部存在交联结构而导致表面形状不规则,有“乳突”现象;而采用预乳化法合成的硅丙微胶乳粒径粗大,呈规则的球形,氨化后粒径从100nm以上减小到80nm左右,粒子表面出现“绒毛”现象,这是由于硅烷组分的水解反应受到抑制而使粒子内部的交联密度降低的缘故。     

外延AgCl/AgBr乳剂感光性能的研究

制备系列AgCl/AgBr八面体外延乳剂,利用EDS-STEM技术对主体乳剂AgBr八面体上氯的分布进行了测定,结果表明随AgCl/AgBr外延乳剂中AgCl含量的增大,而其分布优势始终在AgBr八面体的顶角位置,其次在边。77K时,用375nm的激发光源对外延乳剂AgCl/AgBr样品进行激发,随外延乳剂中AgCl含量的提高,AgCl的发光谱带有增大的趋势,但其峰位置基本保持在510nm左右,AgBr在600nm.AgCl和AgBr的发光峰始终以分立的形式存在,没有混晶AgBrCl的宽谱带出现,外延乳剂AgCl/AgBr的感光度随AgCl含量的提高也有一定的变化规律,当AgCl含量较低时,有明显增感作用,而当AgCl含量过高时,外延乳剂的感光度降低,但灰雾也减小。