The identification of fibers by infrared and Raman microspectroscopy

The application of Raman and infrared microspectroscopy to fiber identification has been investigated. Natural and synthetic fibers, both organic and inorganic in nature, can be rapidly characterized by these techniques. In general, it has been found that infrared microspectroscopy offers a nonsubjective method of fiber identification that is quicker, easier, and occasionally, more selective than classical methods. Raman microspectroscopy has also been proven useful for these analyses. It provides low-frequency information, requires virtually no sample preparation, and supplies data complementary to that furnished by infrared microspectroscopy. In many cases one may use these methods for a quick differentiation of fibers of the same type which have undergone different chemical treatments.     

Mono-(L)-aspartylchlorin-e6

Mono-(L)-aspartylchlorin-e6 (also known as Talaporfin, NPe6, MACE, and most recently LS-11) is a potent sensitizer for photodynamic therapy that is currently undergoing clinical trials. Using a combination of unambiguous partial synthesis from pheophytin-a and methyl pheophorbide-a, NMR spectroscopy, and single crystal X-ray diffraction, the structure of mono-(L)-aspartylchlorin-e6 is definitively shown to be the isomer in which the aspartyl residue is attached at the 15(2)-side chain position. This conclusion is contrary to earlier assumptions, but affirms the conclusions of a study based on NMR spectroscopy; a rationale for the unique formation of the 15(2)-aspartyl derivative is proposed.     

Anisotropic structure and transport in self-assembled layered polymer-clay nanocomposites

Using the layer-by-layer (LbL) assembly technique, we create a polymer-clay structure from a unique combination of LbL materials: poly(ethylene imine), Laponite clay, and poly(ethylene oxide). This trilayer LbL structure is assembled using a combination of hydrogen bonding and electrostatic interactions. The films were characterized using ellipsometry, profilometry, X-ray photon spectroscopy, atomic force microscopy, scanning electron microscopy, wide-angle X-ray diffraction, grazing-incidence small-angle X-ray scattering, and electrochemical impedance spectroscopy (EIS). We observe a layered, anisotropic structure, which resulted in in-plane ion transport 100 times faster than cross-plane at 0% relative humidity. This study represents a first application of EIS in determining anisotropic ion transport in LbL assemblies and its correlation to structural anisotropy.     

Confined micro-explosion induced by ultrashort laser pulse at SiO2/Si interface

Ultrashort laser pulses tightly focused inside a transparent material present an example of laser interaction with matter where all the laser-affected material remains inside the bulk, thus the mass is conserved. In this paper, we present the case where the high intensity of a laser pulse is above the threshold for optical breakdown, and the material is ionised in the focal area. We consider in detail a special case where a micro-explosion is formed at the boundary of a silicon surface buried under a 10-micron-thick oxidised layer, providing the opportunity to affect the silicon crystal by a strong shock wave and creating new material phases from the plasma state. We summarise the main conclusions on ultrafast laser-induced material modifications in confined geometry and discuss the prospects of confined micro-explosion for forming new silicon phases.