Nanocelluloses: a new family of nature-based materials

Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.     

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Modification of guanine residues in PNA-synthesis by PyBOP

The phosphonium-type coupling reagent PyBOP, when applied to the synthesis of peptide nucleic acid (PNA) oligomers, was found to form O⁴-phosphonium compounds of the nucleobase guanine which can be converted into C⁴-modified guanine-derived PNAs by nucleophiles.     

Relative quantum yield for the production of O-atom and S-atom from the photodissociation of OCS in the vacuum UV

The relative efficiencies for two dissociative channels in the vacuum UV photolysis of carbonyl sulphide have been determined using the flash photolysis-resonance fluorescence technique to measure initial yields of atomic oxygen and atomic sulphur. At wavelengths above 105 nm, the dissociation of OCS to form atomic sulphur exceeded that for the formation of atomic oxygen to such an extent that only an upper limit could be placed on the minor process, Φ_S >/ 50 Φ_O. In addition, the flash photo-excitation of carbonyl sulphide produced a long-lived spontaneous emission in the UV and vacuum UV that might be due to molecular fluorescence from OCS.     

DETAILED ACTION SPECTRUM FOR THE DELAY SHIFT IN PUPAE EMERGENCE OF DROSOPHILA PSEUDOOBSCURA*

Abstract— Dose-response curves were measured for the delay phase shift of pupae emergence of Drosophila pseudoobscura. From these curves an action spectrum was determined for this process; it suggests a flavin to be the photoreceptor pigment.