منابع مشابه
the effect of taftan pozzolan on the compressive strength of concrete in the environmental conditions of oman sea (chabahar port)
cement is an essential ingredient in the concrete buildings. for production of cement considerable amount of fossil fuel and electrical energy is consumed. on the other hand for generating one tone of portland cement, nearly one ton of carbon dioxide is released. it shows that 7 percent of the total released carbon dioxide in the world relates to the cement industry. considering ecological issu...
Surprises from the sea floor
Unknown planet: Around 72% of the Earth’s surface is covered by oceans, and much of that surface is still unchartered territory for science. (Graphic: SuperStock.) More than seventy percent of the surface of our planet is covered by oceans. 88 percent of their area is deeper than 1,000 metres and thus difficult to access for research. There are only a handful of research submersibles that can d...
متن کاملExtending the sub-sea-floor biosphere.
Sub-sea-floor sediments may contain two-thirds of Earth's total prokaryotic biomass. However, this has its basis in data extrapolation from ~500-meter to 4-kilometer depths, whereas the deepest documented prokaryotes are from only 842 meters. Here, we provide evidence for low concentrations of living prokaryotic cells in the deepest (1626 meters below the sea floor), oldest (111 million years o...
متن کاملThe Complexity of Kings
A king in a directed graph is a node from which each node in the graph can be reached via paths of length at most two. There is a broad literature on tournaments (completely oriented digraphs), and it has been known for more than half a century that all tournaments have at least one king [Lan53]. Recently, kings have proven useful in theoretical computer science, in particular in the study of t...
متن کاملDragon kings of the deep sea: marine particles deviate markedly from the common number-size spectrum.
Particles are the major vector for the transfer of carbon from the upper ocean to the deep sea. However, little is known about their abundance, composition and role at depths greater than 2000 m. We present the first number-size spectrum of bathy- and abyssopelagic particles to a depth of 5500 m based on surveys performed with a custom-made holographic microscope. The particle spectrum was unus...
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ژورنال
عنوان ژورنال: Nature Reviews Microbiology
سال: 2008
ISSN: 1740-1526,1740-1534
DOI: 10.1038/nrmicro1973