The conformations of the N-H and C=O bonds in the SO(2)-NH-CO-C group of the title compound (N4BPSTMAA), C(11)H(14)BrNO(3)S, are trans to each other, similar to what is observed in N-(4-chloro-phenyl-sulfon-yl)-2,2,2-trimethyl-acet-amide (N4CPSTMAA) and 2,2,2-trimethyl-N-(4-methyl-phenyl--sulfon-yl)acetamide (N4MPSTMAA). The bond para-meters in N4BPSTMAA are similar to those in N4CPSTMAA, N4MPS...

The Rhizobium etli CE3 O antigen is a fixed-length heteropolymer with O methylation being the predominant type of sugar modification. There are two O-methylated residues that occur, on average, once per complete O antigen: a multiply O-methylated terminal fucose and 2-O methylation of a fucose residue within a repeating unit. The amount of the methylated terminal fucose decreases and the amount...

Four new p-aminoacetophenonic acids, named (2E)-11-(4′-aminophenyl)-5,9dihydroxy-4,6,8-trimethyl-11-oxo-undec-2-enoic acid (1), 9-(4′-aminophenyl)-3,7dihydroxy-2,4,6-trimethyl-9-oxo-nonoic acid (2), (2E)-11-(4′-aminophenyl)-5,9-O-cyclo4,6,8-trimethyl-11-oxo-undec-2-enoic acid (3) and 9-(4′-aminophenyl)-3,7-O-cyclo-2,4,6trimethyl-9-oxo-nonoic acid (4), were isolated from an endophyte Streptomyce...

In the crystal structure of the title compound (N4CPSTMAA), C(11)H(14)ClNO(3)S, the conformations of the N-H and C=O bonds in the amide group are anti to each other, similar to those observed in N-phenyl-sulfonyl-2,2,2-trimethyl-acetamide (NPSTMAA) and 2,2,2-trimethyl-N-(4-methyl-phenyl-sulfon-yl)acetamide (N4MPSTMAA). The bond parameters in N4CPSTMAA are similar to those in NPSTMAA, N4MPSTMAA,...

An amphiphilic N-octyl-O-methoxy poly (ethylene glycol) chitosan was successfully prepared by grafting successively octyl groups onto amino groups at chitosan’s C-2 position as hydrophobic moieties and methoxy polyethylene glycol (MPEG) groups onto hydroxyl groups at C-6, C-3 as hydrophilic ones. A certain amount of -NH2 was retained in the structure of chitosan derivatives through protection b...

-a simple, efficient, and general method has been developed for the chemoselective acetalization of aldehydes with 1,3-propanediol, 1,2-ethanediol and trimethyl orthoformate in the presence of solid lithium perchlorate under solvent-free conditions. both cyclic and acyclic acetals of aldehydes were obtained under environmentally benign conditions in good to excellent yields.

Composite coatings containing brushite (CaHPO(4). 2H(2)O) and chitosan were prepared by electrochemical deposition. The brushite/chitosan composites were converted to hydroxyapatite/chitosan composites in aqueous solutions of sodium hydroxide. The coatings ranged from approximately 1 to 15% chitosan by weight. Qualitative assessment of the coatings showed adhesion significantly improved over th...

A DNA/chitosan-Fe₃O₄ magnetic nanoparticle bio-complex film was constructed for the immobilization of horseradish peroxidase (HRP) on a glassy carbon electrode. HRP was simply mixed with DNA, chitosan and Fe₃O₄ nanoparticles, and then applied to the electrode surface to form an enzyme-incorporated polyion complex film. Scanning electron microscopy (SEM) was used to study the surface features of...

Calcium phosphate cements (CPCs) are extensively used as synthetic bone grafts, but their poor toughness limits their use to non-load-bearing applications. Reinforcement through introduction of fibers and yarns has been evaluated in various studies but always resulted in a decrease in elastic modulus or bending strength when compared to the CPC matrix. The aim of the present work was to improve...