Polymorphic and microstructural behaviors of palm oil/lecithin blends crystallized under shear

There has been much work on polymorphism and crystal habit of quiescently crystallized palm oil. However, researchers have found it difficult to probe the process of sheared crystallization. The effect of surface-active molecules as nucleation agents or habit modifiers was demonstrated in quiescent systems. The aim of this work is to explore the effects of shear and specific lecithins (soy and sunflower) on palm oil crystallization by monitoring crystallization under shear using a synchrotron radiation source, as well as microscopy and DSC. It was found that increasing shear led to increasing β′ stabilization in all situations. Soybean lecithin had little effect on behavior. Sunflower lecithin led to even greater β′ stabilization. The different lecithins interact with the crystallizing fat changing rates of nucleation and crystal growth. Thus, the structure of the overall system can be dramatically altered. Microscopy revealed very different structures even if the polymorphism of the different systems was similar. Consequently, specific interactions can be manipulated in order to control the system. In particular, control of lecithin composition affects the stability of the different polymorphs. Palm oil crystallization under realistic processing conditions has been characterized. Under these conditions, increasing shear rates give higher β′ stability. Specific lecithins have different effects. In particular, soybean lecithin is β′ stabilizing, whereas sunflower lecithin has limited effects. Thus the overall structure of lecithin is important in determining the efficacy. This can be applied to control the structure and properties of different systems such as shortenings or spreads where crystalline interactions create the macro-structure that determines product properties.     

Synthesis of Substituted Quinolizidines via a Gold‐Catalyzed Double Cyclization Cascade

A novel synthesis of quinolizidines by a cationic gold‐catalyzed double cyclization cascade has been developed. The reaction was initiated by the gold‐catalyzed 6‐exo‐dig cyclization of ynamides, which was followed by a second cyclization of an enamide intermediate to provide the corresponding quinolizidine derivatives. The utility of this reaction was demonstrated by application to the synthesis of multi‐substituted quinolizidines and by the total synthesis of a quinolizidine alkaloid, (±)‐lupinine.

     

Development of advanced expansion due to compression (A-EDC) test method for safety evaluation of degraded nuclear fuel cladding materials

Expansion due to compression (EDC) test has been applied to evaluate the performance of nuclear fuel claddings where pellet-cladding mechanical interaction (PCMI) is introduced by swelling of fuel pellets and is triggered by the larger hoop deformation of the pellets, especially during accidental transients. The purpose of this study is to modify the EDC test to describe PCMI, specimen volume reduction and others. Ring-shaped specimens were cut from Zry-4 cladding tubes. Cylindrical metal pellets with 8 mm in diameter and 15 mm in maximum height were used as inner pellets. Expansion of the specimens due to the inner pellet compression was performed at room temperature. The experimental data were further analyzed by finite element method. Through the survey in the variation of the specimen and core, specimen size and inner pellet geometry were optimized. Excellent reproducibility with less error was confirmed. The uniaxial tension condition in the hoop direction up to the specimen failure was confirmed. Hoop stress–hoop strain curves were successfully derived.     

Effect and control of path parameters on thickness distribution of cylindrical cups formed via multi-pass conventional spinning

Journal of Intelligent Manufacturing - In this study, an artificial neural network (ANN) model was constructed to investigate the relationship between the roller path parameters to form a...     

Antiatherogenic effect of guava leaf extracts inhibiting leucocyte-type 12-lipoxygenase activity

Oxidative modification of low density lipoprotein (LDL) is one of the critical steps for the development of atherosclerosis and leucocyte-type 12-lipoxygenase, highly expressed in macrophages, has been suggested to play an essential role in this process. In the present study, we show that guava leaf extracts inhibited, not only the leucocyte-type 12-lipoxygenase activity, but also LDL oxidation, mediated by the enzyme-overexpressing macrophage-like J774A.1 cells. Oral administration of guava leaf extracts to apoE-knockout mice at 100 mg of dry extracts/kg of body weight, once a day for 16 weeks, significantly reduced the area of atherogenic lesions developed in the aorta and aortic sinus. The major components inhibiting leucocyte-type 12-lipoxygenase contained in guava leaf extracts were identified as ethyl gallate and quercetin. The inhibitory effects of guava leaf extracts on the leucocyte-type 12-lipoxygenase activity, as well as on cell-mediated LDL oxidation, might be involved in the antiatherogenic effect of the extracts.