Sharif Digital Repository

A crude phenolic glycolipid extract from Mycobacterium bovis BCG was fractionated by column chromatography. A reversed-phase high performance liquid chromatography (HPLC) method with UV detection at 275nm was developed for simultaneous detection and separation of phenolic glycolipids (PGLs) in Mycobacterium bovis BCG. This analysis provides a good resolution. Different solvent systems and columns for HPLC were compared. A system composed of acetonitrile-water in the ratio of 0→80% at a flow rate of 0.8 mL/min and C8 analytical column were found to be optimum for HPLC of the phenolic glycolipids. This simple method is therefore appropriate to purify these compounds present in M. bovis extract... 

Hantzsch 1, 4-dihydropyridines (1,4-DHPs) can be oxidized to the corresponding pyridine derivatives by thallium triacetate in high yields  

The combined effects of SiC and carbon additives on the densification, structure and characteristics of pressureless sintered ZrB2-SiC ceramic composites were studied. The ZrB2-SiC (1-10wt%) composite powders were mixed by 1-2wt% carbon. The prepared powder mixtures were then cold-consolidated and sintered in argon environment in the temperature range of 1800-2100°C for 2h. The constituted phases and microstructural evolutions were studied using x-ray diffraction and scanning electron microscope equipped with an energy dispersive x-ray detector. The obtained results concluded that the densification was increased by extending the sintering time and also by prior holding... 

In this research, the pressureless sintering of ZrB 2 composites were studied to obtain the highest densification and investigate the effects of TiC (2–10% wt) and graphite (1–2% wt) additives on the sinterability. The results showed that by adding TiC, the porosity and water absorption of the samples decreased, resulting in an increase in the density of the samples up to ~98% of the theoretical density. The addition of graphite and TiC reduced the surface oxide layers, improved the density and prevented the grain growth. The graphite additive reacted with B 2 O 3 and ZrO 2 and allowed the system to achieve a complete densification at 2000 °C. Both TiC and graphite additives were completely...