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Nearly 95 percent of the world demand for molybdenum-99 (Mo-99)—perhaps the world's most important medical isotope—is met by just four manufacturers, all of whom use highly enriched uranium (HEU) targets in their isotope production programs. Research and development on the use of low-enriched uranium targets and gel generators to produce Mo-99 began in the 1980s; some success has been achieved, but Mo-99 is still mainly produced by irradiating HEU targets in a reactor. Fission-produced Mo-99 has a high specific activity, but activation methods provide low specific activity Mo-99, which is unsuitable for the generators routinely used in most of the world's medical centers. This article evaluates the use of enriched Mo-98 to produce Mo-99 by activation methods; the use of medium specific activity Mo-99 for the preparation of alumina-based generators is also discussed. This article concludes that if support is provided for the production of enriched Mo-98, it may replace to a significant extent the use of HEU and LEU for the production of Mo-99.  相似文献   
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In this paper eight successive experimental blast tests with an increasing TNT equivalent charge weights ranging from 0.56 kg to 17.78 kg were conducted on unreinforced, ferrocemented overlay masonry and confined masonry walls. The pressure-time history caused by the blast was recorded by pressure sensors installed on the test specimen. The resulting damage pattern was observed during each test. Weak zones in the three systems of masonry were identified. Scaled distances for different damage levels in the three masonry systems were experimentally obtained. The results provide a basis for determining the response of each masonry system against blast loading. Consequently, efficiency of ferrocemented overlay ma-sonry and confined masonry was found established in mitigation against blast loads.  相似文献   
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The drone is the latest tool to promote interests of a nation-state. It is clear that USA as well as other major powers anticipate that robotics will play a key role in future warfare. Today, more than 70 countries have already acquired drone technology and many others are desperate to join the ranks. This urge for drone technology will ultimately lead to a “boundless and borderless war without end.” In the case of Pakistan, the US drone campaign has raised some important issues regarding how their use could, or should, be regulated in the future. This article analyses the legal issues raised by the US's use of drone technology in non-combat zones, such as Pakistan. It is argued that a reckless disrespect of Pakistan's sovereignty has had adverse implications and consequences for the legitimacy of the Pakistani government. Drone strikes have prompted instinctive opposition among the Pakistani population, hurt their feelings and estranged them from the government. This in turn has added to Pakistan's instability and stimulated a ground-swell of animosity toward the USA.  相似文献   
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