Ammonium nitrate fuel oil is an explosive mixture found in most antipersonnel landmines (APL) buried throughout the Colombian territory. During more than 50 years of internal conflict, the Colombian government has found that trained dogs are the most effective method to detect APL. However, the olfactive signature in ANFO is unknown and also if there are differences in detection related to the explosive manufacturing origin. Therefore, this work begins with the analytical validation of the method used to determine ammonia, in its derivatized form as carbamate, released by home-made ANFO using HS-SPME-GC-FID. Once validated, the method was used to identify ammonia and other organic volatile compounds present in ANFO, under laboratory and simulated field conditions. The validation process includes the evaluation of the optimum conditions for the derivation and extraction of butylcarbamate, the determination of the working ranges with linear response in FID, the limits of detection and quantification, the sensitivity, and the precision. The results of the validation established linearity and sensitivity in a concentration between 20 and 120 mg/L, as well as low limits of detection and quantification of 6.4 and 21.4 mg/L, respectively. Also, an intermediate precision of 11% for butylcarbamate with a repeatability of 8%. The validated method showed in real samples of home-made ANFO besides ammonia, the presence of low molecular methylamines, and also exhibited differences in volatile compositions according to the origin. The objective of this work is to offer a reliable analytical methodology for the extraction and analysis of volatile compounds from ANFO. 相似文献
The Olsonian distinction between roving and stationary bandits outlines the rationale behind the transition from anarchy to the emergence of the predatory state. This two-bandit model may, however, be expanded to include more bandit types. In the case of Viking Age England, local English kings were unable to monopolize violence and defend their realms against competing Viking raiders. As the Vikings’ time horizon grew, so did the accumulated value of more formal taxation, and bandit types evolved in four steps. The first step is the Olsonian roving bandit, who executed Viking hit-and-run attacks and plunders during the second half of the tenth century. The second step is the gafol bandit; gafol is payment for leaving, paid to, among others, Swein Forkbeard. The third step is the heregeld bandit; heregeld is a tax to support an army for hire; most notably Thorkell the Tall’s. The fourth step is the Olsonian stationary bandit, i.e. the strongest military leader among the Vikings, Cnut the Great, settled down as the new king. Overall, the Olsonian two-bandit model can be expanded to a four-bandit staircase model, in which the new gafol and heregeld bandit types explain the steps from anarchy and short-run raiding to long-run formal taxation in a predatory state.
This article explores how the UK’s fact-checking organisation Full Fact has sought to tackle misinformation since its inception in 2010. Full Fact describes itself as a ‘second generation’ fact-checking organisation with dual aims of seeking to stop the spread of specific pieces of inaccurate information and using the evidence base from fact checking to secure systemic changes that help make misinformation rarer and less harmful. Ultimately, we are pursuing culture change. We are trying to create institutions in societies that can help anchor public debate to reality and to challenge the casual acceptance of deceptive and misleading behaviour. 相似文献