Simple And Temperature-insensitive Pressure Sensing Based On A Hollow-core Photonic Crystal Fiber

The sensitivity to pressure of lossy air-guided modes in a commercial hollow-core photonic crystal fiber was experimentally exploited to develop a novel pressure sensor. The transmission of these modes was directly modulated by the measurand, which makes the interrogation system very simple. Using a supercontinuum source, these specific modes were identified within the visible spectral range and correspond to narrow transmission windows well away from the fiber's main bandgap, centered around 1550 nm. The origin of these windows is being investigated but is likely to be related to cladding bandgaps. One of these windows, around 633 nm, was used for the analysis presented in this paper. An attenuation increase was observed when pressure was applied to a ∼3-cm long cell, which was traversed by the fiber. The attenuation reached 5 dB with 300kgf/cm2 gauge pressure. The transmission was found to be insensitive to temperature up to 100°C, which is a highly attractive feature for sensing applications. It was also found that much higher sensitivities (a few dB attenuation with ∼0.5kgf/cm2 gauge pressure) could be obtained when pressure was internally applied to the fiber microstructure. This fact allows for the construction of sensors with a wide range of sensitivities, which can, thus, suit different applications. Transmission within the infrared bandgap was insensitive to pressure and can serve as a reference. © American Institute of Physics.1055129132Knight, J.C., (2003) Nature, 424, pp. 847-851Alkeskjold, T.T., Lægsgaard, J., Bjarklev, A., Hermann, D.S., Broeng, J., Li, J., Gauza, S., Wu, S.-T., (2006) Appl. Opt, 45, pp. 2261-2264Cordeiro, C.M.B., de Matos, C.J.S., dos Santos, E.M., Bozolan, A., Ong, J.S.K., Facincani, T., Chesini, G., Brito Cruz, C.H., (2007) Meas. Sci. Technol, 18, pp. 3075-3081Jensen, J.B., Pedersen, L.H., Hoiby, P.E., Nielsen, L.B., Hansen, T.P., Folkenberg, J.R., Riishede, J., Bjarklev, A., (2004) Opt. Lett, 29, pp. 1974-1976Krohn, D.A., Pressure Sensors (2000) Fiber Optic Sensors, pp. 143-151. , Research Triangle Park: Instrument Society of AmericaXu, M.G., Reekie, L., Chow, Y.T., Dakin, J.P., (1993) Electron. Let, 29, pp. 398-399Hsu, Y.S., Wang, L., Fung Liu, W., Chiang, Y.J., (2006) IEEE Photon. Technol. Let, 18, pp. 874-876Nasilowski, T., (2005) Appl. Phys. B, 81, pp. 325-331Bock, W.J., Chen, J., Eftimov, T., Urbanczyk, W., (2006) IEEE T. Instrum. Meas, 55, pp. 874-876Shinde, Y.S., Gahir, H.K., (2008) IEEE Photon. Technol. Let, 20, pp. 279-28

Average bioequivalence of single 500 mg doses of two oral formulations of levofloxacin: a randomized, open-label, two-period crossover study in healthy adult Brazilian volunteers

Average bioequivalence of two 500 mg levofloxacin formulations available in Brazil, Tavanic(c) (Sanofi-Aventis Farmacêutica Ltda, Brazil, reference product) and Levaquin(c) (Janssen-Cilag Farmacêutica Ltda, Brazil, test product) was evaluated by means of a randomized, open-label, 2-way crossover study performed in 26 healthy Brazilian volunteers under fasting conditions. A single dose of 500 mg levofloxacin tablets was orally administered, and blood samples were collected over a period of 48 hours. Levofloxacin plasmatic concentrations were determined using a validated HPLC method. Pharmacokinetic parameters Cmax, Tmax, Kel, T1/2el, AUC0-t and AUC0-inf were calculated using noncompartmental analysis. Bioequivalence was determined by calculating 90% confidence intervals (90% CI) for the ratio of Cmax, AUC0-t and AUC0-inf values for test and reference products, using logarithmic transformed data. Tolerability was assessed by monitoring vital signs and laboratory analysis results, by subject interviews and by spontaneous report of adverse events. 90% CIs for Cmax, AUC0-t and AUC0-inf were 92.1% - 108.2%, 90.7% - 98.0%, and 94.8% - 100.0%, respectively. Observed adverse events were nausea and headache. It was concluded that Tavanic(c) and Levaquin(c) are bioequivalent, since 90% CIs are within the 80% - 125% interval proposed by regulatory agencies

Extrudované antirezonantní optická vlákna s dutým jádrem z teluritu pro střední infračervenou oblast

We report the first extruded tellurite antiresonant hollow core fibers (HC-ARFs) aimed at the delivery of mid-infrared (Mid-IR) laser radiation. The preform extrusion fabrication process allowed us to obtain preforms with non-touching capillaries in a single step, hence minimizing thermal cycles. The fibers were fabricated from in-house synthetized tellurite glass (containing Zn, Ba and K oxides) and co-drawn with a fluorinated ethylene propylene (FEP) polymer outer layer to improve their mechanical properties and protect the glass from humidity. The fabricated HC-ARFs transmit in the Mid-IR spectral range from 4.9 to 6 mu m. We measured losses of similar to 8.2, 4.8 and 6.4 dB/m at 5 mu m, 5.6 gm and 5.8 mu m, respectively in two different fibers. These losses, which are dominated by leakage mostly arising from a non-uniform membrane thickness, represent the lowest attenuation reported for a tellurite-based HC-ARF to date. The fibers present good beam quality and an M^2 factor of 1.2. Modelling suggests that by improving the uniformity in the capillary membrane thickness losses down to 0.05 dB/m at 5.4 gm should be possible, making this solution attractive, fbr example, for beam delivery from a CO laser.Tento článek se zabývá extrudovanými antirezonantními optickými vlákny s dutým jádrem z teluritu pro přenos laserového záření ve střední infračervené oblasti (HC-ARF). Proces výroby vytlačování předlisku nám umožnil získat předlisky s nedotýkajícími se kapilárami v jednom kroku, čímž se minimalizovaly tepelné cykly. Vlákna byla vyrobena ze syntetizovaného skla z telluritu (obsahujícího oxidy Zn, Ba a K) a společně tažena s vnější vrstvou polymeru z fluorovaného ethylenpropylenu (FEP), aby se zlepšily mechanické vlastnosti a sklo chránilo před vlhkostí. Vyrobené HC-ARF byly použity pro přenos ve spektru Mid-IR od 4,9 do 6 um. Byly naměřeny ztráty blízké 8,2, 4,8 a 6,4 dB / m při 5 μm, 5,6 gm a 5,8 μm, a to ve dvou různých vláknech. Tyto ztráty, kterým dominuje netěsnost většinou způsobená nerovnoměrnou tloušťkou membrány, představují doposud nejnižší útlum zaznamenaný pro HC-ARF na bázi teluritu. Vlákna vykazují dobrou kvalitu paprsku a faktor M^2 1,2. Modelování naznačuje, že zlepšením rovnoměrnosti v tloušťce kapilární membrány by mělo být možné ztráty snížit až na 0,05 dB / m při 5,4 gm, což by mělo učinit toto řešení atraktivním, například pro dodávku paprsku z CO laseru