The Colloidal Characteristics of Blended Crudes

Abstract

Iran and Saudi crude oils were selected to be studied in this article. The characteristics of colloid were investigated at the optimum active status (the distillation yield is higher than the theoretical distillation yield). The experimental results show that at optimized blending ratio, vacuum residue becomes denser, the precipitation point of vacuum residue advances, and the aggregation of colloidal particles becomes strong. It was found that the interaction of the functional groups after blending was similar to previous blending. However, at the optimized blending ratio the signals of hydrogen bond and condensed aromatic rings weakened.     

表面活性剂对二氧化硅溶胶稳定性的影响

研究了表面活性剂对二氧化硅溶胶粘度和稳定性的影响.在二氧化硅溶胶中添加不同表面活性剂,测定了该混合体系的粘度变化和稳定性,结果表明阴离子表面活性剂可以降低硅溶胶的粘度,其CMC大约在4.6×10~(-3) mol/L左右,阴离子表面活性剂可以提高硅溶胶稳定性,极值为1.43×10~(-3) mol/L.表面活性剂SDBS对溶胶粘度的影响与其在溶胶颗粒上的包覆有关,SDBS对溶胶的稳定作用是由于SDBS胶束的形成,溶胶颗粒对SDBS的吸附会降低溶胶的稳定性.阴离子和非离子表面活性剂能提高二氧化硅溶胶稳定性,而阳离子表面活性剂会降低溶胶稳定性.     

Localized surface plasmon resonance enhanced photoluminescence of CdSe QDs in PMMA matrix on silver colloids with different shapes

Localized surface plasmon resonance (LSPR) enhanced photoluminescences (PL) from CdSe quantum dots (QDs) on worm-like or quasi-spherical silver colloids have been investigated. The shape of silver colloid film is controlled by annealing temperature (200 °C∼350 °C). Strong PL enhancements of CdSe QDs on both as-grown and annealed silver colloid films are observed. The results show that the PL enhancement factor of CdSe QDs on worm-like silver colloid film reaches as high as 15-fold. Moreover, the enhancement factor is 5 times larger than that obtained from the quasi-spherical silver colloids. The superiority of worm-like silver nanostructure on LSPR enhanced photoluminescence is attributed to its larger size, hot spots and multiple dipole resonance modes coupling, which are induced by aggregation effect.     

Colloidal Self‐Assembly Meets Nanofabrication: From Two‐Dimensional Colloidal Crystals to Nanostructure Arrays

Self‐assembly of colloidal microspheres or nanospheres is an effective strategy for fabrication of ordered nanostructures. By combination of colloidal self‐assembly with nanofabrication techniques, two‐dimensional (2D) colloidal crystals have been employed as masks or templates for evaporation, deposition, etching, and imprinting, etc. These methods are defined as “colloidal lithography”, which is now recognized as a facile, inexpensive, and repeatable nanofabrication technique. This paper presents an overview of 2D colloidal crystals and nanostructure arrays fabricated by colloidal lithography. First, different methods for fabricating self‐assembled 2D colloidal crystals and complex 2D colloidal crystal structures are summarized. After that, according to the nanofabrication strategy employed in colloidal lithography, related works are reviewed as colloidal‐crystal‐assisted evaporation, deposition, etching, imprinting, and dewetting, respectively.     

Morphological characterization of composite latex particles by positron annihilation lifetime spectroscopy

A series of thermoplastic/elastomer composite particles has been prepared by two step emulsion polymerization techniques. The morphology of the obtained composite particles as a function of the system composition has been studied by transmission electron microscopy. Afterwards, a correlation between the structural behavior of the composites and the ortho- positronium lifetime and formation probability was also established. This correlation can be explained in terms of free volume changes associated to phase transitions in the particles. Received: 18 December 2000 / Reviewed and accepted: 4 April 2001     

Colloid Emulsion of Nanosized Strontium Bismuth Tantalate Powder

A novel colloid-emulsion process has been used to synthesize nanosized strontium bismuth tantalate (SrBi₂Ta₂O₉) particles. During calcination, the desired bismuth-layered structure phase develops at the expense of the pyrochlore phase. Calcining the precursor powder at 750°C for 2 h leads to the complete formation of single-phase layered-structured SrBi₂Ta₂O₉. The powder that is formed consists of nanoparticles with a narrow size distribution and almost-spherical morphology. The crystallinity of the calcined powder increases as the calcination temperature and heating time increases. The developed colloid-emulsion process significantly reduces the SrBi₂Ta₂O₉ particle size, in comparison to conventional process techniques, and results in a uniform microstructure of the obtained powder.     

Lipid Oxidation in Oil‐in‐Water Emulsions: Involvement of the Interfacial Layer

More polyunsaturated fats in processed foods and fewer additives are a huge demand of public health agencies and consumers. Consequently, although foods have an enhanced tendency to oxidize, the usage of antioxidants, especially synthetic antioxidants, is restrained. An alternate solution is to better control the localization of reactants inside the food matrix to limit oxidation. This review establishes the state‐of‐the‐art on lipid oxidation in oil‐in‐water (O/W) emulsions, with an emphasis on the role of the interfacial region, a critical area in the system in that respect. We first provide a summary on the essential basic knowledge regarding (i) the structure of O/W emulsions and interfaces and (ii) the general mechanisms of lipid oxidation. Then, we discuss the factors involved in the development of lipid oxidation in O/W emulsions with a special focus on the role played by the interfacial region. The multiple effects that can be attributed to emulsifiers according to their chemical structure and their location, and the interrelationships between the parameters that define the physicochemistry and structure of emulsions are highlighted. This work sheds new light on the interpretation of reported results that are sometimes ambiguous or contradictory.     

食品胶对甘薯淀粉膜性能的响应面法优化实验

以机械性能(抗张强度、断裂拉伸应变)和透湿性为指标,研究食品胶对甘薯淀粉膜性能的优化。结果表明：羟丙基羧甲基纤维素(HPCMC)添加量为3.5～4.0g/100g 淀粉、甘油添加量小于2.0g/100g 淀粉及黄原胶添加量小于2.0g/100g 淀粉时,膜的机械性能较好;HPCMC 添加量小于2.0g/100g 淀粉、甘油添加量大于4.0g/100g 淀粉和黄原胶添加量小于1.5g/100g 淀粉时,膜的透湿性较小。由于不同性能的优化值范围不完全相同,在实际应用中可根据对不同性能的要求进行选择。     

Role of physical structures in bulk oils on lipid oxidation

Lipid oxidation is important to food manufacturers especially when they increase unsaturated lipids in their products to improve nutritional profiles. Unfortunately, the number of antioxidants available to food manufacturers to control oxidative rancidity is limited and the approval of new antioxidants is unlikely due to economic barriers in obtaining government approval for new food additives. Therefore, new antioxidant technologies are needed for food oils. This paper reviews the current knowledge of lipid oxidation in foods with emphasis on how physical properties of food systems impact oxidation chemistry. In particular, the role of association colloids in bulk oils on lipid oxidation chemistry is discussed in an attempt to understand mechanisms of oxidation. Increasing the understanding of how physical properties impact lipid oxidation could lead to the development of novel antioxidant technologies that not only protect the oil against oxidation and increase shelf-life but also allow food manufacturers to include more nutritionally beneficial fatty acids in their products.