The behavior of completely siliceous zeolite ZSM-5 (Si-ZSM-5) under high pressures up to 16 GPa were investigated by in situ Raman spectroscopy and X-ray diffraction with synchrotron radiation in a diamond anvil cell. Pressure-induced amorphization was observed in both as-made and calcined Si-ZSM-5, which transform to a low-density amorphous silica first and then to a high-density amorphous silica. However, transition pressures and reversibility were different for as-made and calcined Si-ZSM-5. It was found that the existence of the template molecules occluded in the zeolite framework is mainly responsible for these differences.

This work highlights the possibility of using microstructured fibres with predefined doped regions to produce functional microstructures at a fibre facet with differential chemical etching. A specially designed silica microstructured fibre (MSF) that possesses specific boron-doped silica regions was fabricated for the purpose of generating a radial micronozzle array. The MSF was drawn from a preform comprising pure silica capillaries surrounded by boron-doped silica rods. Different etching rates of the boron-doped and silica regions at the fiber facet produces raised nozzles where the silica capillaries were placed. Fabrication parameters were explored in relation to the fidelity and protrusion length of the nozzle. Using etching alone, the nozzle protrusion length was limited, and the inner diameter of the channels in the array is expanded. However with the addition of a protective water counter flow, nozzle protrusion is increased to 60 μm with a limited increase in hole diameter. The radial micronozzle array generated nine individual electrosprays which were characterized using spray current measurements and related to theoretical prediction. Signal enhancement for the higher charge state ions for two peptides showed a substantial signal enhancement compared to conventional emitter technology.

Microstructured fibers (MSFs) having raised polymer nozzles in each channel are custom designed, fabricated, and tested for use as multiple electrospray (MES) emitters for mass spectrometry (MS). There is strong motivation to develop electrospray emitters that operate at practical flow rates but give the much greater ionization efficiency associated with lower (nano) flow rates. This can be accomplished by splitting the flow into many lower-volume electrosprays, an approach known as MES. To couple with most modern mass spectrometers, the MES emitter must have a small diameter to allow efficient ion collection into the MS. In this work, a MSF, defined as a fiber having many empty channels running along its length, was designed to have 9 channels, 9 μm each, >100 μm apart arranged in a radial pattern, all in a fiber having a compatible diameter with both front-end LC equipment and typical MS inlets. This design seeks to promote independent electrospray from each channel while maintaining electric field homogeneity. While the MSFs themselves do not support MES, the formation of polymer nozzles protruding from each channel at the tip face enables independent electrospray from each nozzle. Microscope imaging, electrospray current measurement, and ESI-MS detection of a model analyte all confirm the MES behavior of the 9-nozzle emitter, showing significant signal enhancement relative to a single-nozzle emitter at the same total flow rate. LC/MS data from a protein digest obtained at an independent laboratory demonstrates the applicability and robustness of the emitter for real scientific challenges using modern LC/MS equipment.

Small-scale, one-dimensional structures are of great interest for their applicability in fields as diverse as medicine, catalysis, microelectronics and chemical analysis. Such structures include tubes, fibres/wires, and other extended linear forms. One popular approach to fabricating 1D structures is to form them inside a template and then remove the template, typically by selective chemical etching. In this work, microstructured fibres (MSFs) were used as a template to generate tubes, wires and porous monoliths from poly(divinylbenzene) or poly(butyl acrylate-co-butanediol diacrylate). MSFs are designed and marketed as photonic waveguides, and consist of an array of parallel channels fashioned in silica. The MSF manufacturing process typically involves stacking a number of tubes and rods in a preformed array followed by heating and drawing to a thin fibre. This process allows tight control over the channel size and shape, and as such these parameters are highly consistent between channels and between MSFs. Consequently, the 1D structures formed from these template channels share their low polydispersity, as well as their other characteristics such as ultrahigh aspect ratio and axial alignment.

The purpose of this study was to test the hypothesis that skeletal muscle relaxants could inhibit the in vitro metabolism of common comedications opioids buprenorphine, methadone and oxycodone. The compounds [solubility-limited concentration (μM) studied] were as follows: baclofen (1000), carisoprodol (200), its metabolite meprobamate (1000), chlorzoxazone (200), cyclobenzaprine (1000), metaxalone (50), methocarbamol (1000), orphenadrine (1000) and tizanidine (1000). Compounds were first incubated with human liver microsomes ± pre-incubation, screened with pathway-specific cDNA-expressed cytochrome P450s (rCYP), and then IC values determined using either 8-concentration tests for those where the rCYP screen suggested an IC was achievable, or a 3-concentration test with downward extrapolation if screen suggested 50% inhibition was not achievable. These results were then extrapolated to determine an inhibitory potential. Six pathway inhibitor combinations were identified with a moderate inhibitory potential (≥2.0 < 5.0): five with chlorzoxazone, R-EDDP, S-EDDP and noroxycodone production by CYP3A4, and R- and S-EDDP production by CYP2B6; and one for the meprobamate effect on noroxycodone production by CYP3A4. An additional eleven combinations were found with a weak inhibitory potential (≥1.25 < 2.0): five with carisoprodol, two each with methocarbamol and meprobamate, and one each with metaxalone and orphenadrine. This represents the first comprehensive study of the inhibitory effect of this class of drugs and suggests that some of them may produce significant drug-drug interactions with opioids that are frequent comedications with skeletal muscle relaxants.