Formation of novel thiazolomorphinans and thiazoloaporphines

A novel strategy has been developed for the synthesis of ring A fused thiazolomorphinans and ring D fused thiazoloaporphines offering the possibility of formation of regioisomeric products. The conventional thermal thiazole-forming reaction was replaced with microwave initiation and a detailed discussion has been presented on the proposed mechanism of the ring closure.     

Role of structure-proteins in the porphyrin–DNA interaction

We studied the complexation of meso-tetrakis(4-N-methylpyridyl)porphyrin (TMPyP) with HeLa nucleosomes and compared it to our earlier results on T7 phage nucleoprotein complex (NP) and isolated DNA. To identify binding modes and relative concentrations of the bound TMPyP forms, the porphyrin absorption spectra were analyzed at various base pair/porphyrin ratios. Spectral decomposition and circular dichroism measurements proved that the two main binding modes of TMPyP, i.e., external binding and intercalation occur also in the nucleosomes. The DNA superstructure maintained by the proteins decreases its accessibility for TMPyP similarly in both nucleoproteins. A difference is observed between the partitioning of the two binding modes: in the case of nucleosome the ratio of intercalation to groove-binding is changed from 60/40 to 40/60 as determined for T7 NP and for isolated DNA-s. Using UV and CD melting studies, we revealed that TMPyP destabilizes the DNA–protein interaction in the nucleosomes but not in the T7 phage. Lastly, photoinduced reaction of bound TMPyP caused alterations in DNA structures and DNA–protein interactions within both nucleoprotein complexes; the nucleosomes were found to be more sensitive to the photoreaction.     

Cavitation assisted delignification of wheat straw: a review

Wheat is grown in most of the Indian and Chinese regions and after harvesting, the remaining straw offers considerable promise as a renewable source most suitable for papermaking and as a pulping resource. Delignification of wheat straw offers ample scope for energy conservation by way of the application of the process intensification principles. The present work reviews the pretreatment techniques available for improving the effectiveness of the conventional approach for polysaccharide component separation, softening and delignification. A detailed overview of the cavitation assisted delignification process has been presented based on the earlier literature illustrations and important operational guidelines have been presented for overall low-cost and amenable energy utilization in the processes. The effectiveness of the methods has been evaluated according to yield and properties of the isolated fibers in comparison to the conventional treatment. Also the experimental results of one such non-conventional treatment scheme based on the use of hydrodynamic cavitation have been presented for the pulping of wheat straw. The effect of hydrodynamically induced cavitation on cell wall matrix and its components have been characterized using FT-IR analysis with an objective of understanding the cavitation assisted digestion mechanism on straws. It has been observed that the use of hydrodynamic cavitation does not degrade the fibrillar structure of cellulose but causes relocalisation and partial removal of lignin. Overall it appears that considerable improvement can be obtained due to the use of pretreatment or alternate techniques for delignification, which is an energy intensive step in the paper making industries.     

Hydrogenation of biological membranes using a polymer-anchored colloidal palladium catalyst

Colloidal palladium anchored onto the surface of insoluble polyvinyl-polypirrolidone (Pd-PVPP) is anactive, non-permeable catalyst for surface selective hydrogenation of model or isolated biomembranes.

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HPTLC Assessment of Phenolic Extractives in Selected Extraneous Woods

JPC – Journal of Planar Chromatography – Modern TLC -     

TLC Analysis of the In-Vitro Reaction of Beech (Fagus sylvatica L.) Wood Enzyme Extract with Catechins

JPC – Journal of Planar Chromatography – Modern TLC - The factors affecting the economically and sylviculturally disadvantageous formation of red heartwood in beech are only partly...     

Metalation/functionalization sequences applied to 2-bromo-3-fluoroquinolines

Mono- and disubstituted 2-bromo-3-fluoroquinolines 3 are readily accessible. They can be converted into the 3-fluoroquinoline-2-carboxylic acids 5 by consecutive halogen/metal permutation and into the 2-bromo-3-fluoroquinoline-4-carboxylic acids 6 by consecutive deprotonation and carboxylation. The latter compounds can be reduced to afford the 3-fluoroquinoline-4-carboxylic acids 7. The yields are excellent throughout. Rather than to introduce one functional group alternatively at the 2- or 4-position, one may also attach two different functional groups sequentially to both sites.     

Colloidal metal dispersions as catalysts for selective surface hydrogenation of biomembranes, 1. Preparation and characterization of palladium catalysts

Paliadium sols containing largely uniform, nanosize metallic, particles stabilized by poly(N-vinyl-2-pyrrolidone) were found to be active microheterogeneous catalysts for hydrogenation of water soluble olefinic substrates as well as of unsaturated lipid dispersions. The same metallic particles were supported on the surface of crosslinked insoluble poly(N-vinyl-2-pyrrolidone) and served as easily removable macroheterogeneous hydrogenation catalysts.