http://hdl.handle.net/10344/21 Sun, 05 Nov 2017 08:35:21 GMT 2017-11-05T08:35:21Z http://ulir.ul.ie:80/bitstream/id/418/SElogo.jpg http://hdl.handle.net/10344/21 http://hdl.handle.net/10344/6229 Solution synthesis of lead seeded germanium nanowires and branched nanowire networks and their application as Li-ion battery anodes Flynn, Grace; Palaniappan, Kumaranand; Sheehan, Martin; Kennedy, Tadhg; Ryan, Kevin M Herein, we report the high density growth of lead seeded germanium nanowires (NWs) and their development into branched nanowire networks suitable for application as lithium ion battery anodes. The synthesis of the NWs from lead seeds occurs simultaneously in both the liquid zone (solution-liquid-solid (SLS) growth) and solvent rich vapor zone (vapor-liquid-solid (VLS) growth) of a high boiling point solvent growth system. The reaction is sufficiently versatile to allow for the growth of NWs directly from either an evaporated catalyst layer or from pre-defined nanoparticle seeds and can be extended to allowing extensive branched nanowire formation in a secondary reaction where these seeds are coated onto existing wires. The NWs are characterized using TEM, SEM, XRD and DF-STEM. Electrochemical analysis was carried out on both the single crystal Pb-Ge NWs and the branched Pb-Ge NWs to assess their suitability for use as anodes in a Li-ion battery. Differential capacity plots show both the germanium wires and the lead seeds cycle lithium and contribute to the specific capacity that is approximately 900 mAh/ g for the single crystal wires, rising to approximately 1100 mAh/ g for the branched nanowire networks. peer-reviewed; The full text of this article will not be available in ULIR until the embargo expires on the 1/6/2018 Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10344/6229 2017-01-01T00:00:00Z http://hdl.handle.net/10344/6221 Modelling and understanding powder flow properties and compactability of selected active pharmaceutical ingredients, excipients and physical mixtures from critical material properties Worku, Zelalem Ayenew; Kumar, Dinesh; Gomes, João Victor; He, Yunliang; Glennon, Brian; Ramisetty, Kiran A; Rasmuson, Åke C; O'Connell, Peter; Gallagher, Kieran H; Woods, Trevor; Shastri, Nalini R; Helay, Anne-Marie The development of solid dosage forms and manufacturing processes are governed by complex physical properties of the powder and the type of pharmaceutical unit operation the manufacturing processes employs. Suitable powder flow properties and compactability are crucial bulk level properties for tablet manufacturing by direct compression. It is also generally agreed that small scale powder flow measurements can be useful to predict large scale production failure. In this study, predictive multilinear regression models were effectively developed from critical material properties to estimate static powder flow parameters from particle size distribution data for a single component and for binary systems. A multilinear regression model, which was successfully developed for ibuprofen, also efficiently predicted the powder flow properties for a range of batches of two other active pharmaceutical ingredients processed by the same manufacturing route. The particle size distribution also affected the compactability of ibuprofen, and the scope of this work will be extended to the development of predictive multivariate models for compactability, in a similar manner to the approach successfully applied to flow properties. peer-reviewed; The full text of this article will not be available in ULIR until the embargo expires on the 9/8/2018 Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10344/6221 2017-01-01T00:00:00Z http://hdl.handle.net/10344/6214 Preparation and characterization of amorphous ciprofloxacin-amino acid salts Mesallati, Hanah; Conroy, Daryl; Hudson, Sarah; Tajber, Lidia The amorphization of the poorly soluble drug ciprofloxacin (CIP) may be facilitated by the use of a suitable stabilizer. In this study seven amino acids, with various side chain properties, were evaluated in this regard. Solid dispersions were prepared by ball milling 1:1 molar ratios of CIP with the amino acids, and their solid-state and pharmaceutical properties were then examined. Fully X-ray amorphous solid dispersions were obtained with aspartic acid, glutamic acid, cysteine and arginine. In each case, evidence of salt formation between the drug and amino acids was found via Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance. In contrast, semi-crystalline solid dispersions were obtained with serine, alanine and glycine. The glass transition temperatures of the amorphous salts were significantly higher than those of the starting materials, and they remained fully X-ray amorphous during long-term stability studies. Significant improvements in the solubility of CIP were also observed with the amorphous salts in water and simulated biological fluids, over and above that of the corresponding physical mixtures. In permeability studies on the other hand, the amorphous aspartate and glutamate salts were found to be less permeable than the pure drug, whereas formulation as an amorphous salt containing cysteine or arginine increased the permeability of CIP. Therefore, while amorphous salt formation with amino acids appears to be a suitable means of improving the thermal stability and solubility of CIP, in some cases this is associated with a decrease in permeability. peer-reviewed; The full text of this article will not be available in ULIR until the embargo expires on the 15/9/2018 Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10344/6214 2017-01-01T00:00:00Z http://hdl.handle.net/10344/6211 Electrochemical study of an electron shuttle diheme protein: the cytochrome c550 from T. thermophilus Melin, Frederic; Schoepp-Cothenet, Barbara; Abdulkarim, Saleh; Noor, Mohamed R; Soulimane, Tewfik; Hellwig, Petra Cytochrome c550 , a diheme protein from the thermophilic bacterium Thermus thermophilus, is involved in an alternative respiration pathway allowing the detoxification of sulfite ions. It transfers the two electrons released from the oxidation of sulfite in a sulfite:cytochrome c oxidoreductase (SOR) enzyme to heme/copper oxidases via the monoheme cytochrome c552. It consists of two conformationally independent and structurally different domains (the C- and N-terminal) connected by a flexible linker. Both domains harbor one heme moiety. We report here the redox properties of the full-length protein and the individual C- and N-terminal fragments. We show by UV/Vis and EPR potentiometric titrations that the two fragments exhibit very similar potentials, despite their different environments. In the full-length protein, however, the N-terminal heme is easier to reduce than the C-terminal one, due to cooperative interactions. This finding is consistent with the kinetic measurements which showed that the N-terminal domain only accepts electrons from the SOR. Cytochrome c552 is able to interact with its partners both through electrostatic and hydrophobic interactions as could be shown by measuring efficient electron transfer at gold electrodes modified with charged and hydrophobic groups, respectively. The coupling of electrochemistry with infrared spectroscopy allowed us to monitor the conformational changes induced by electron transfer to each heme separately and to both simultaneously. peer-reviewed; The full text of this article will not be available in ULIR until the embargo expires on the 8/5/2019 Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10344/6211 2017-01-01T00:00:00Z