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Photo-induced environmental depletion processes of b-blockers in river waters
Liu, Qin-Tao,Cumming, Rob I.,Sharpe, Alan D. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.6
In order to improve the understanding of the fate and behaviour of pharmaceuticals in the environment there is a need to investigate in-stream depletion mechanisms, e.g. phototransformation of active pharmaceutical ingredients (APIs) in natural surface waters. In this study, abiotic and biotic degradation of selected $\beta$-blockers was measured simultaneously in non-sterilised and sterilised river waters and deionised water (DIW) under simulated sunlight ($\lambda$: 295.800 nm) and dark conditions, and at environmentally relevant concentrations, i.e. $\leq$ ppb levels. Results suggested that the overall degradation followed pseudo first order kinetics under the solar simulation conditions and was between two and ten times faster in river waters than in DIW. There was a significant correlation (p < 0.07) between dissolved organic carbon (DOC) and overall first order degradation rate constants for the tested b-blockers (n = 4-6), suggesting coloured DOC triplet-induced or reactive transient mediated oxidation mechanisms in river waters. Phototransformation was the main depletion mechanism for the b-blockers tested over a 2 to 7 day period. Slow hydrolysis was observed for metoprolol only. Loss due to biodegradation in river waters was not observed for propranolol but was found for metoprolol and atenolol at a very slow rate within the study period. However, biodegradation of metoprolol was accelerated under the light conditions, implying that photo-induced intermediates could be more easily biodegraded in river waters.
Analysis of silicon terahertz diffractive optics
E. D. Walsby,S. M. Durbin,D. R. S. Cumming,R. J. Blaikie 한국물리학회 2004 Current Applied Physics Vol.4 No.2-4
Simulations of silicon diractive lenses for terahertz frequencies have been performed using a Fraunhofer wave propagationmodel to show how the lens eciency can be aected by dierent fabrication defects. A general model is presented to illustrate theoperating bounds which must be adhered to when fabricating a lens using a multiple level process. From these simulations it ispossible to ascertain for a specic lens design with known processing inaccuracies what level of design complexity will gain the mostbenet. It is shown that for a 1 THz lens fabricated using an eight level process the lens eciency is reduced by less than 20% forrealistic values of etch non-uniformity, inter-level misalignment and surface roughness.
CUMMINGS, JENNIFER E.,BARRETT, CONOR D.,LITWAK, KENNETH N.,DI BIASE, LUIGI,CHOWDHURY, PUNAM,OH, SEIL,CHING, CHI KEONG,SALIBA, WALID I.,SCHWEIKERT, ROBERT A.,BURKHARDT, J. DAVID,DE MARCO, SHARI,ARMAGAN Blackwell Publishing Inc 2008 Journal of cardiovascular electrophysiology Vol.19 No.6
<P><I>Introduction:</I> Evaluation of luminal temperature during left atrial ablation is used clinically; however, luminal temperature does not necessarily reflect temperature within the esophageal wall and poses a risk of atrioesophageal fistula. This animal study evaluates luminal esophageal temperature and its relation to the temperature of the external esophageal tissue during left atrial lesions using the 8 mm solid tip and the open irrigated tip catheters (OIC).</P><P><I>Methods and Results:</I> A thermocouple was secured to the external surface of the esophagus at the level of the left atrium of the dogs. Luminal esophageal temperature was measured using a standard temperature probe. In four randomized dogs, lesions were placed using an 8 mm solid tip ablation catheter. In six randomized dogs, lesions were placed using the 3.5 mm OIC. The average peak esophageal tissue temperature when using the OIC was significantly higher than that of the 8 mm tip catheter (88.6°C ± 15.0°C vs. 62.3°C ± 12.5°C, P < 0.05). Both OIC and 8 mm tip catheter had significantly higher peak tissue temperatures than luminal temperatures (OIC: 88.6°C ± 15.0°C vs 39.7°C ± 0.82°C, P < 0.05) (8 mm: 62.3°C ± 12.5°C vs 39.0 ± 0.5°C, P < 0.05). Both catheters achieved peak temperatures faster in the tissue as compared to the lumen of the esophagus, although the tissue temperature peaked significantly faster for the OIC (OIC: 25 seconds vs 90 seconds, P < 0.05) (8 mm: 63 seconds vs 105 seconds, P < 0.05).</P><P><I>Conclusion:</I> Despite the significant difference in actual tissue temperatures, no significant difference was observed in luminal temperatures between the OIC and 8 mm tip catheter.</P>
Clapham, Hannah,Cummings, Derek A. T.,Nisalak, Ananda,Kalayanarooj, Siripen,Thaisomboonsuk, Butsaya,Klungthong, Chonticha,Fernandez, Stefan,Srikiatkhachorn, Anon,Macareo, Louis R.,Lessler, Justin,Reis Public Library of Science 2015 PLoS neglected tropical diseases Vol.9 No.12
<▼1><P><B>Background</B></P><P>Infants born to dengue immune mothers acquire maternal antibodies to dengue. These antibodies, though initially protective, decline during the first year of life to levels thought to be disease enhancing, before reaching undetectable levels. Infants have long been studied to understand the interaction between infection and disease on an individual level.</P><P><B>Methods/Findings</B></P><P>Considering infants (cases <1 year old) as a unique group, we analyzed serotype specific dengue case data from patients admitted to a pediatric hospital in Bangkok, Thailand. We show differences in the propensity of serotypes to cause disease in individuals with dengue antibodies (infants and post-primary cases) and in individuals without dengue antibodies (primary cases). The mean age of infant cases differed among serotypes, consistent with previously observed differential waning of maternal antibody titers by serotype. We show that trends over time in epidemiology of infant cases are consistent with those observed in the whole population, and therefore with trends in the force of infection.</P><P><B>Conclusions/Significance</B></P><P>Infants with dengue are informative about the interaction between antibody and the dengue serotypes, confirming that in this population DENV-2 and DENV-4 almost exclusively cause disease in the presence of dengue antibody despite infections occurring in others. We also observe differences between the serotypes in the mean age in infant cases, informative about the interaction between waning immunity and disease for the different serotypes in infants. In addition, we show that the mean age of infant cases over time is informative about transmission in the whole population. Therefore, ongoing surveillance for dengue in infants could provide useful insights into dengue epidemiology, particularly after the introduction of a dengue vaccine targeting adults and older children.</P></▼1><▼2><P><B>Author Summary</B></P><P>Infants born to dengue immune mothers acquire maternal dengue antibodies. These antibodies, though initially protective, decline during the first year of life to levels thought to be disease enhancing, before reaching undetectable levels. We show that in this population, DENV-2 and DENV-4 almost exclusively cause disease in the presence of dengue antibody, despite infections occurring in others. We also observe serotype-specificity in the mean age of infant cases, consistent with differential waning of antibody to each serotype. These results highlight serotype-specificity in the way the immune response interacts with infection to cause disease. In addition, we show that the mean age of infant cases over time is informative about transmission in the whole population. Therefore, ongoing surveillance for dengue in infants could provide useful insights into dengue epidemiology, particularly after the introduction of a dengue vaccine targeting adults and older children.</P></▼2>