眼镜蛇蛇油中甘油三酸酯的成分研究

用ＡｇＮＯ３－硅胶薄层板，氯仿＋丙酮（２０＋１）为展开剂，将蛇油中甘油三酸酯分离为５个组分，并用同样的色谱固定相和石油醚－氯仿－丙酮溶剂系统进行制备性分离。用质谱法对甘油三酸酯进行分子一级水平的化学研究，确定了眼镜蛇蛇油中５个主要的甘油三酸酯成分的结构形式为：１６∶０－１８∶０－１８∶０，１６∶０－１８∶０－１８∶１，１６∶０－１８∶２－１８∶１，１８∶２－１８∶２－１８∶０，１８∶２－１８∶２－１８∶１。     

Electrical interaction between two cylinders with an ion-penetrable charged membrane in an oil/water interface

The electrical interaction between two long, parallel cylinders each is covered by an ion-penetrable charged membrane immersed in an oil/water interface is investigated. The effects of contact angle, radius of cylinder, and membrane thickness on the electrical interaction force are examined. The results of numerical simulation reveal that the following conditions lead to a greater electrical interaction force: (i) a larger contact angle, i.e. a larger fraction of a cylinder in the oil phase; (ii) a larger cylinder radius; and (iii) a thinner membrane. For a fixed ionic strength, the electrical interaction force is insensible to the type of electrolytes in the water phase, in general. However, if two cylinders are close enough, then the higher the valence of counterions the greater the electrical interaction force.     

Analysis of tinuvin 1577 polymer additive in edible oils using on-line coupled HPLC-GC

An application of automated on-line HPLC-HRGC is described for direct analysis of edible oils for migrated polymer additives. The sample preparation, separating the additive from the oil triglycerides, is carried out using normal phase HPLC. The fraction of the eluent containing the additive is automatically transferred to a HRGC where a second and final separation of the additive from minor oil components takes place. The method compares well with off-line separation methods. Migration data for Tinuvin 1577 from PET and PC polymers as well as an unspecified experimental polymer is given. The advantages and disadvantages of using different edible oils as food simulants are discussed.     

The Electrochemistry of Tetraphenyl Porphyrin Iron(III) Within Immobilized Droplets Supported on Platinum Electrodes

For the first time, the voltammetry of an ensemble of immobilized benzonitrile microdroplets containing 5,10,15,20‐tetraphenyl‐21H,23H‐porphine iron (III) chloride, TPPFeCl immobilized at platinum electrodes immersed in various aqueous electrolytes has been explored. The reduction of TPPFeCl was observed with the voltammetric response seen to be highly dependent on the nature of ions in the surrounding aqueous phase. Unlike voltammetry in purely homogeneous solution the nature of the aqueous electrolyte can influence the voltammetry in the droplet phase. The electrochemical reduction of TPPFeCl contained within tetrabutylammonium chloride (TBACl) supported benzonitrile (PhCN) microdroplets immersed into an aqueous solution of TBACl was first studied. During TPPFeCl reduction the resulting [TPPFeCl]^? species is stabilized due to the excess of chloride anions inside the oil droplet. Voltammograms of homogeneous solutions of PhCN supported with TBACl show similar chemically reversible process which is also attributed to the stable [TPPFeCl]^? species. This anion stabilization was not observed when the oil droplets were supported with tetrabutylammonium perchlorate (TBAP) or when the PhCN solution bathing the microdroplet ensemble was supported with TBAP resulting in a chemically irreversible process. The voltammetry of unsupported droplets immobilized on a platinum electrode immersed in different aqueous electrolytes was also explored and the fate of the [TPPFeCl]^? species formed considered during the reduction sweep. Similarities and difference to voltammetry in purely homogeneous media are noted and the use of droplet voltammetry provides complimentary information.     

Colloidal forces between bitumen surfaces in aqueous solutions measured with atomic force microscope

Colloidal forces between bitumen surfaces in aqueous solutions were measured with an atomic force microscope (AFM). The results showed a significant impact of solution pH, salinity, calcium and montmorillonite clay addition on both long-range (non-contact) and adhesion (pull-off) forces. Weaker long-range repulsive forces were observed under conditions of lower solution pH, higher salinity and higher calcium concentration. Lower solution pH, salinity and calcium concentration resulted in a stronger adhesion forces. The addition of montmorillonite clays increased long-range repulsive forces and decreased adhesion forces, particularly when co-added with calcium ions. The measured force profiles were fitted with extended DLVO theory to show the repulsive electrostatic double layer and attractive hydrophobic forces being the dominant components in the long-range forces between the bitumen surfaces. At a very short separation distance (less than 4–6 nm), a strong repulsion of steric origin was observed. The findings provide a fundamental understanding of bitumen emulsion stability and a mechanism of bitumen “aeration” in bitumen recovery processes from oil sands.     

近红外(NIRS)技术分析小样品油菜籽芥酸和含油量的应用研究

以完整油菜籽为样品,采用旋转杯和安培瓶两种样品杯、每种样品分为4×2种不同样品量并通过不同光谱预处理来优化油菜籽芥酸和含油量的近红外分析模型。结果表明:油菜籽各小样品含油量模型的决定系数(R2)从93.93%到96.93%不等,均方差(RMSECV)从0.56到0.79不等;油菜籽各小样品芥酸模型的决定系数(R2)从96.91%到98.42%不等,均方差(RMSECV)从1.73到2.43不等。随着样品量的逐渐增加,油菜籽芥酸和含油量不同样品杯模型各参数逐渐有所优化;同一样品厚度时,油菜小样品芥酸和含油量的旋转样品杯模型各参数均略优于安培瓶样品模型;不同样品量的NIRS模型,W3和W4差异不大,依次优于W2和W1。最小样品量AW1为0.3g。优化油菜小样品模型时,应该选择全部的预处理方法,根据优化结果选择最佳模型。外部检验结果表明:不同重量小样品(W1/0.3g、W2/1.0g、W3/2.0g和W4/4.0g)模型之间及其与标准化学值之间在0.01水平上差异不显著,说明W1和W2小样品模型同样可应用于油菜品质育种材料的分析选择。     

Screening the origin and weathering of oil slicks by attenuated total reflectance mid-IR spectrometry

The combination of attenuated total reflectance-fourier transform mid-infrared spectrometry (ATR-FTMIR) and multivariate pattern recognition is presented as a fast and convenient methodology to ascertain the source product an oil slick comes from and to evaluate the extent of its weathering. Different types of hydrocarbons (including crude oils, several heavy distillates and the Prestige's heavy fuel oil) were spilled on metallic containers designed ad hoc and their fate monitored by ATR-FTMIR. Not only environmental conditions were considered for weathering but artificial IR- and UV-irradiation. Pattern-recognition studies revealed that the different hydrocarbons clustered at different locations on the score plots and that the samples corresponding to each oil became ordered according to the extent of their weathering. Among them, fuel oil samples coming from the recent disaster of the Prestige tanker off the Galician shoreline showed a distinctive behaviour. Comparison of natural-, IR- and UV-weathering of a crude oil showed that IR solar radiation can be important in oil-weathering, in addition to broadly-reported UV degradation.     

Influence of extractions on physicochemical characterization and bioactivity of Piper nigrum oils: Study on the non-isothermal decomposition kinetic

Black pepper oils have been investigated frequently in the recent years. However, there is a significant variation in physicochemical properties and bioactivity of oils depended on extraction techniques. In this study, the systemic investigation of four various extraction methods was performed to evaluate the physicochemical characterizations, antioxidant and antibacterial activity. The investigation of ¹H NMR, FTIR and UV–Vis spectra confirmed presence of non-volatile components in oils extracted through supercritical CO₂ and hexane-soaking extractions which induced their typical thermal properties. The isothermal behaviour of extracted oils related to evaporation was within range of 3.2–7.3% (w/w) at 27 °C. The SEM images of the black pepper confirmed different operation manners of mechanism between extractions using the solvents and heating process. The lowest MIC for both essential oils from conventional hidrodistillation and microwave-assisted hidrodistillation against two bacteria including E. coli and B. subtilis were found to be 137 µg mL⁻¹. The non-isothermal decomposition kinetics were investigated on the essential oil of microwave-assisted hydrodistillation extraction. The activation energies and pre-exponent factors of non-isothermal decomposition were found to be in range of 36.5–73.7 KJ mol⁻¹ and 4.98 × 10³–1.97 × 10⁸ s⁻¹, respectively, dependent on conversional fractions of the oil. The results revealed that chemical components, physicochemical properties and bioactivity of black pepper essential oils depended on the extraction techniques.     

Role of self-assembled surfactant structure on the spreading of oil on flat solid surfaces

Uniform spreading of oil on solid surfaces is important in many processes where proper lubrication is required and this can be controlled using surfactants. The role of oil–solid interfacial self-assembled surfactant structure (SASS) in oil spreading is examined in this study for the case of hexadecane-surfactant droplet spreading on a flat horizontal copper surface, with triphenyl phosphorothionate surfactants having varying chain lengths (0 to 9). It is shown that the frictional forces (F_SASS) as determined by the SASS regulate droplet spreading rate according to surfactant chain length; surfactants with longer chains led to higher reduction in the spreading rate. The extent of such forces, F_SASS, depends on the surfactant density of the evolving SASS, and specific configuration the evolving SASS exhibit as per the orientations of the surfactant chains therein. Thus, F_SASS = [k₁ + k_2(t)] Γ_δ(t), where Γ_δ(t) is the surfactant adsorption density of SASS at time ‘t’ during evolution, and, k₁ and k_2(t) are the force coefficients for Γ_δ(t) and orientations (as a function of spreading time) of the surfactant chains respectively. As a SASS evolves/grows along with adsorption of surfactants at the spreading induced fresh interface, the k₁Γ_δ(t) component of F_SASS increases and contributes to reduction in the net spreading force (S). With a decrease in the net spreading force, the existence of a cross-over period, during which the transition of the spatial dynamics of the chains from disordered to realignment/packing induced ordered orientation occurs, has been inferred from the F_SASS vs. chain length relationships. Such relationships also suggested that the rate of realignment/packing is increased progressively particularly due the realignment/packing induced decrease in the net spreading force. Therefore, the realignment process is a self-induced process, which spans a measurable period of time (several minutes), the cross-over period, during which the net spreading force decreases essentially due to such self-induced process.     

Superhydrophobic MoS2-based multifunctional sponge for recovery and detection of spilled oil

Oil spills are a major threat to the marine ecosystem, requiring immediate solutions to remove spilled oil from oceanic environments. In this study, we report a superhydrophobic molybdenum disulfide (MoS₂) coated polydimethylsiloxane (PDMS) sponge and demonstrate its high proficiency in spilled oil recovery and oil spill detection based on oil-water separation ability. This novel oil sorbent is fabricated by a simple dip-coating to incorporate MoS₂ flakes into PDMS sponge. The optimized MoS₂-sponge displays a water contact angle of >152°, demonstrating excellent superhydrophobicity and high oil absorption (>97 wt%) for a variety of oils, including vegetable oil and fuel waste. Moreover, the material retains excellent oil absorption capability upon repetitive compression cycles. The versatility of this novel sorbent has been extended for the real-time spontaneous detection of oils by taking advantage of electrically conductive MoS₂ layers.