Development and evaluation of a suite of isotope reference gases for methane in air

Measurements from multiple laboratories have to be related to unifying and traceable reference material in order to be comparable. However, such fundamental reference materials are not available for isotope ratios in atmospheric methane, which led to misinterpretations of combined data sets in the past. We developed a method to produce a suite of synthetic CH4-in-air standard gases that can be used to unify methane isotope ratio measurements of laboratories in the atmospheric monitoring community. Therefore, we calibrated a suite of pure methane gases of different methanogenic origin against international referencing materials that define the VSMOW (Vienna Standard Mean Ocean Water) and VPDB (Vienna Pee Dee Belemnite) isotope scales. The isotope ratios of our pure methane gases range between -320 and +40% for delta H-2-CH4 and between -70 and -40% for delta C-13-CH4, enveloping the isotope ratios of tropospheric methane (about -85 and -47% for delta H-2-CH4 and delta C-13-CH4 respectively). Estimated uncertainties, including the full traceability chain, are</p

Effect of UV radiation and temperature on the emission of methane from plant biomass and structural components

The recently reported finding that plant matter and living plants produce significant amounts of the important greenhouse gas methane under aerobic conditions has led to an intense scientific and public controversy. Whereas some studies question the up-scaling method that was used to estimate the global source strength, others have suggested that experimental artifacts could have caused the reported signals, and two studies, one based on isotope labeling, have recently reported the absence of CH&lt;sub&gt;4&lt;/sub&gt; emissions from plants. Here we show – using several independent experimental analysis techniques – that dry and detached fresh plant matter, as well as several structural plant components, emit significant amounts of methane upon irradiation with UV light and/or heating. Emissions from UV irradiation are almost instantaneous, indicating a direct photochemical process. Long-time irradiation experiments demonstrate that the size of the CH&lt;sub&gt;4&lt;/sub&gt; producing reservoir is large, exceeding potential interferences from degassing or desorption processes by several orders of magnitude. A dry leaf of a pure &lt;sup&gt;13&lt;/sup&gt;C plant produces &lt;sup&gt;13&lt;/sup&gt;CH&lt;sub&gt;4&lt;/sub&gt; at a similar rate as dry leaves of non-labeled plants produce non-labeled methane

Результати ексгумації останків загиблих солдатів у центрі селища Цумань у 2010 р.

В статті висвітлюються результати археологічних досліджень Цуманської рятівної експедицією ДП « Волинські Старожитності» ДП НДЦ ОАСУ ІА НАН України, проведених у червні 2010 р. на місцезнаходженні останків солдатів Червоної армії часів Другої світової війни у центрі селища Цумань Ківерцівського району Волинської області

Helium-oxygen reduces the production of carbon dioxide during weaning from mechanical ventilation

<p>Abstract</p> <p>Background</p> <p>Prolonged weaning from mechanical ventilation has a major impact on ICU bed occupancy and patient outcome, and has significant cost implications.</p> <p>There is evidence in patients around the period of extubation that helium-oxygen leads to a reduction in the work of breathing. Therefore breathing helium-oxygen during weaning may be a useful adjunct to facilitate weaning. We hypothesised that breathing helium-oxygen would reduce carbon dioxide production during the weaning phase of mechanical ventilation.</p> <p>Materials/patients and methods</p> <p>We performed a prospective randomised controlled single blinded cross-over trial on 19 adult intensive care patients without significant airways disease who fulfilled criteria for weaning with CPAP. Patients were randomised to helium-oxygen and air-oxygen delivered during a 2 hour period of CPAP ventilation. Carbon dioxide production (VCO₂) was measured using a near patient main stream infrared carbon dioxide sensor and fixed orifice pneumotachograph.</p> <p>Results</p> <p>Compared to air-oxygen, helium-oxygen significantly decreased VCO₂production at the end of the 2 hour period of CPAP ventilation; there was a mean difference in CO₂production of 48.9 ml/min (95% CI 18.7-79.2 p = 0.003) between the groups. There were no significant differences in other respiratory and haemodynamic parameters.</p> <p>Conclusion</p> <p>This study shows that breathing a helium-oxygen mixture during weaning reduces carbon dioxide production. This physiological study supports the need for a clinical trial of helium-oxygen mixture during the weaning phase of mechanical ventilation with duration of weaning as the primary outcome.</p> <p>Trial registration</p> <p>ISRCTN56470948</p

Gravitational Radiation from Gamma-Ray Burst Progenitors

We study gravitational radiation from various proposed gamma-ray burst (GRB) progenitor models, in particular compact mergers and massive stellar collapses. These models have in common a high angular rotation rate, and the final stage involves a rotating black hole and accretion disk system. We consider the in-spiral, merger and ringing phases, and for massive collapses we consider the possible effects of asymmetric collapse and break-up, as well bar-mode instabilities in the disks. We calculate the strain and frequency of the gravitational waves expected from various progenitors, at distances based on occurrence rate estimates. Based on simplifying assumptions, we give estimates of the probability of detection of gravitational waves by the advanced LIGO system from the different GRB scenarios.Comment: 26 pages, 5 figures, accepted for publication in Ap