Applications of silica supports in affinity chromatography

The combined use of silica-based chromatographic supports with immobilized affinity ligands can be used in many preparative and analytical applications. One example is the use of silica-based affinity columns in HPLC, giving rise to a method known as high-performance affinity chromatography (HPAC). This review discusses the role that silica has played in the development of affinity chromatography and HPAC and the applications of silica in these methods. This includes a discussion of the types of ligands that have been employed with silica and the methods by which these ligands have been immobilized. Various formats have also been presented for the use of silica in affinity chromatographic methods, including assays involving direct or indirect analyte detection, on-line or off-line affinity extraction, and chiral separations. The use of silica-based affinity columns in studies of biological systems based on zonal elution and frontal analysis methods will also be considered.     

On the solution of a third order linear homogeneous difference equation with variable coefficents

A closed form solution of a third order linear homogeneous difference equation with variable coefficients is presented. From it, the solution for the special case of an equation with constant coefficients is also obtained.     

Electrical characterization of ion conducting biopolymeric gel complexes

Gum Arabica is a naturally occurring conducting biomaterial biopolymer, its various aspects of electrical and structural characteristics have been investigated in our earlier works. In the present work the ionic gel formation of Gum Arabica and its electro-chemical application were experimentally investigated. Hot concentrated aqueous solution of Gum Arabica with phosphoric acid, minimum 16% of solute, was found to form ionic hydrogel on slow cooling. It consists of polyelectrolyte molecules cross-linked by phosphate ions by chemical bonds into an integrated spatial network in water solvent. The increase in surface to volume ratio shows a gel collapse to provide transparent solid material. Gel formation of Gum Arabica was also studied with chromium and molybdenum oxide as cross-linking agent. The various studies carried out on the mentioned materials to investigate its structural and electrical characteristics are XRD, DSC, SEM and impedance spectroscopy. The said gel was found to provide a good electro-chemical cell with suitable redox pair.     

Mechanistic studies of the triggered release of liposomal contents by matrix metalloproteinase-9

Matrix metalloproteinases (MMPs) constitute a class of extracellular-matrix-degrading enzymes overexpressed in many cancers and contribute to the metastatic ability of the cancer cells. We have recently demonstrated that liposomal contents can be released when triggered by the enzyme MMP-9. Herein, we report the results of our mechanistic studies of the MMP-9-triggered release of liposomal contents. We synthesized peptides containing the cleavage site for MMP-9 and conjugated them with fatty acids to prepare the corresponding lipopeptides. By employing circular dichroism (CD) spectroscopy, we demonstrated that the lipopeptides, when incorporated into liposomes, are demixed in the lipid bilayers and generate triple-helical structures. MMP-9 cleaves the triple-helical peptides, leading to the release of the liposomal contents. Other MMPs, which cannot hydrolyze triple-helical peptides, fail to release the contents from the liposomes. We also observed that the rate and extent of release of the liposomal contents depend on the mismatch between the acyl chains of the synthesized lipopeptide and phospholipid components of the liposomes. CD spectroscopic studies imply that the observed differences in the release reflect the ability of the liposomal membrane to anneal the defects following the enzymatic cleavage of the liposome-incorporated lipopeptides.     

Conforming finite element methods for the von Kármán equations

In this paper, we consider canonical von Kármán equations that describe the bending of thin elastic plates defined on polygonal domains. A conforming finite element method is employed to approximate the displacement and Airy stress functions. Optimal order error estimates in energy, H ¹ and L ² norms are deduced. The results of numerical experiments confirm the theoretical results obtained.     

New fluorescent probes for carbonic anhydrases

We report the synthesis and fluorescence properties of naphthalenesulfonamide derivatives as active site probes for carbonic anhydrases.     

Experimental investigation for stability and surface properties of TiO2 and Al2O3 water-based nanofluids

Journal of Thermal Analysis and Calorimetry - Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport,...     

The Development of Bulky Palladium NHC Complexes for the Most-Challenging Cross-Coupling Reactions

Palladium‐catalyzed cross‐coupling reactions enable organic chemists to form C? C bonds in targeted positions and under mild conditions. Although phosphine ligands have been intensively researched, in the search for even better cross‐coupling catalysts attention has recently turned to the use of N‐heterocyclic carbene (NHC) ligands, which form a strong bond to the palladium center. PEPPSI (pyridine‐enhanced precatalyst preparation, stabilization, and initiation) palladium precatalysts with bulky NHC ligands have established themselves as successful alternatives to palladium phosphine complexes. This Review shows the success of these species in Suzuki–Miyaura, Negishi, and Stille–Migita cross‐couplings as well as in amination and sulfination reactions.