Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis

EFEITO DO CREEP FEEDING E CREEP GRAZING NAS CARACTERÍSTICAS DA PASTAGEM DE TIFTON E AZEVÉM E NO DESEMPENHO DE OVINOS

The objective of this study was to evaluate the influence of creep feeding and creep grazing on the pasture characteristics and on performance and productivity of sheep. Three systems of lambs production on Tifton 85 (Cynodon spp.) pastures oversown with Italian ryegrass (Lolium multiflorum Lam) were studied: lambs with dams until slaughter without supplementation (1); lambs with dams until slaughter fed concentrate in creep feeders at 2% BW.day-1 (2); and lambs with dams until slaughter and supplemented with white clover (Trifolium repens) in creep grazing system ad libitum (3). The characteristics of the pasture did not differ (P>0.05) among the systems. Individual lamb growth was higher with creep feeding (307g/day) and creep grazing (274g/day) compared to no supplemented systems (204g/day; p<0.05). Animal productivity per area on supplemented treatments (2.4 kg BW/ha/day) was significantly greater than no supplemented one (1.8kg BW/ha/day; p<0.05). White clover showed to be a particularly good supplement for raising lambs on pastures. It may be concluded that systems of feeding lambs in creep feeding and creep grazing yielded favorable productivity mainly if there is forage deficit in spring