Simulated moving bed chromatography for the separation of enantiomers

Simulated moving bed (SMB) chromatography, a continuous multi-column chromatographic process, has become one of the preferred techniques for the separation of the enantiomers of a chiral compound. Several active pharmaceutical ingredients, including blockbuster drugs, are manufactured using the SMB technology. Compared to single column preparative chromatography, SMB separations achieve higher productivity and purity, while reducing the solvent consumption. The SMB technology has found applications both at small and large scales. Design methods have been developed for robust operation and scale-up, using data obtained from analytical experiments. In the last few years, rapid developments have been made in the areas of design, improved process schemes, optimization and robust control. This review addresses these developments, as well as both the fundamentals of the SMB science and technology and some practical issues concerning the operation of SMB units. Particular emphasis is placed on the consolidation of the “triangle theory”, a design tool that is used both in the academia and industry for the design of SMB processes.     

Quick Microwave Assisted Synthesis and <Emphasis Type="Italic">In Vitro</Emphasis> Imaging Application of Oxygen Doped Fluorescent Carbon Dots

In this paper, a fast and simplest one-pot tactic was used to synthesis fluorescent oxygen doped carbon dots from Tween-20 (TTO-CDs) is reported. The TTO-CDs were microwavically synthesized by using Tween-20 as both the carbon precursor and the oxygen dopant as well. The surface morphology, crystalline and/or amorphous nature, composition and optical assets of synthesized TTO-CDs were studied by means of existing techniques. From the results, it was confirmed that the as-synthesized TTO-CDs are amorphous in nature, monodispersed, sphere-shaped and the typical particle size range is 5?±?1.5 nm. The synthesized TTO-CDs emits strong blue fluorescence at 390 nm under excitation of 335 nm. Most interestingly, the excitation dependent emission property of synthesized TTO-CDs was exposed from fluorescence results. The synthesized TTO-CDs have quantum yield of about 14% against quinine sulfate as reference standard. The biotoxicity of synthesized TTO-CDs on HeLa cells was assessed through cytotoxicity assay. These results implied that the fluorescent TTO-CDs showed less biotoxicity, and further which was efficaciously applied as a multicolor staining and bioimaging probe for the confocal imaging of HeLa cells.     

An investigation of PVdF/PVC-based blend electrolytes with EC/PC as plasticizers in lithium battery applications

Solid polymer electrolytes (SPEs) composed of poly(vinylidene fluoride) (PVdF)-poly(vinyl chloride) (PVC) complexed with lithium perchlorate (LiClO₄) as salt and ethylene carbonate (EC)/propylene carbonate (PC) as plasticizers were prepared using solvent-casting technique, with different weight ratios of EC and PC. The amorphicity and complexation behavior of the polymer electrolytes were confirmed using X-ray diffraction (XRD) and FTIR studies. TG/DTA and scanning electron microscope (SEM) studies explained the thermal stability and surface morphology of electrolytes, respectively. The prepared thin films were subjected to AC impedance measurements as a function of temperature ranging from 302 to 373 K. The temperature-dependence conductivity of polymer films seems to obey VTF relation.     

The anti-inflammatory activity of metal complexes and salts of amine carboxyboranes

The metal complexes and salts of amine carboxyboranes were shown to be potent anti-inflammatory agents in rodents at 8 mg kg^?1. They were effective in blocking induced edema, pleurisy and endotoxic shock while blocking both local and central pain processes. The ability of the agents to function as anti-inflammatory agents is multi-fold. First, lysosomal enzymes of specific cells, e.g. macrophages, were inhibited with IC₅₀ values in the range of 10^?6 M . Collagenase I and II activities were inhibited with IC₅₀ values approximately equal to 10^?4 M . The anti-inflammatory activity of these agents at the molecular levels appears to be due to inhibition of the release of TNFα and Il-1 from macrophages which indirectly control chemotaxic migration of white blood cells as indicated by the suppression of PMN and macrophage invasion into sponges implanted subcutaneously (SC) in mice. Furthermore, in these invading cells, the agents' blockage of TNFα and Il-1 or Il-2 release down-regulates prostaglandin and leukotriene enzymatic synthetic rates and, consequently, their release, resulting in a reduction of the inflammation process.     

Synthesis and properties of polyester based polyurethanes

Hydroxyl terminated polyesters were prepared by a melt condensation technique using adipic acid and various diols. They were characterised by hydroxyl number, acid number and intrinsic viscosities in benzene. The polyesters were reacted with excess tolylene diisocyanate to yield isocyanate terminated prepolymers and subsequently cured with diols and diamines. These polymers were characterised by i.r. spectra, viscosity measurements and thermogravimetric analysis. The glass transition temperature of the polymers were found to be in the region ?25 to ?55. The influences of prepolymers and curing reagents are discussed with respect to the low temperature flexibility and thermal stability of the polyurethanes.     

Synthesis and characterization of certain aromatic azopolyamides

Two new aromatic diamines, 2,2′-dimethyl-4,4′-diaminoazobenzene [benzenamine-(3,3′-dimethyl-4,4′-azobis)] and 2,2′-dichloro-4,4′-diaminoazobenzene [benzenamine-(3,3′-dichloro-4,4′-azobis)] were synthesized and their structures confirmed by IR, UV-visible, ¹H-NMR, ¹³C-NMR, and mass spectra. With these diamines, 16 aromatic polyamides were synthesized by both low-temperature solution and phosphorylation polycondensation methods. The polymers were characterized by viscosity, solubility, IR, UV visible, TGA, and DTA studies.     

Thermal and ionic conductivity studies of plasticized PMMA/PVdF blend polymer electrolytes

Poly(methylmethacrylate) (PMMA)/poly(vinylidene fluoride) (PVdF) blend based electrolyte films containing different lithium salt concentrations are prepared using solvent casting technique. The complexation has been confirmed using XRD and FTIR spectral studies. Ionic conductivity and thermal behaviour of PMMA/PVdF complexes were studied with various salt concentrations, temperature and plasticizer content. The network structure of the polymer complexes are also investigated using SEM. The maximum value of conductivity 4.2×10⁻³ S/cm is obtained for the PMMA(7.5)-PVdF(17.5)-LiClO₄(8)-DMP(67) polymer complex at 303 K.