Kjemi

Diskusjon om teknologi, teknologiske fremskritt, ny vitenskap, etc.

Kjemi

Innlegg QIQrrr 23 Des 2010, 02:35

Kungliga Tekniska Högskolan, December 21, 2010: Trinitramid, så kallas den nya molekylen som bland annat är en möjlig komponent i framtida raketbränslen. Drivmedel som i så fall skulle vara 20-30 procent effektivare i jämförelse med de bästa raketbränslen som finns idag. "En tumregel är att för varje tioprocentig effektivitetsökning av raketbränslet kan raketens last fördubblas. Dessutom innehåller molekylen bara kväve och syre, vilket skulle göra raketbränslet miljövänligt. Det är mer än vad man kan säga om dagens fasta raketdrivmedel som innebär att motsvarande 550 ton koncentrad saltsyra släpps ut för varje uppskjuten rymdfärja," säger Tore Brinck, professor i fysikalisk kemi på KTH - KTH-forskare har upptäckt ny molekyl

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Børge Svanstrøm Amundsen

"Atlas was permitted the opinion that he was at liberty, if he wished, to drop the Earth and creep away; but this opinion was all that he was permitted" - Franz Kafka
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QIQrrr
 
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Re: Kjemi

Innlegg QIQrrr 16 Jan 2011, 13:14

MIT, January 14, 2011: In a finding that has been met with surprise and some controversy in the scientific community, researchers at MIT and elsewhere have discovered a basic property that governs the way water and many other liquids behave as their temperature changes. Liquids have long been known to exhibit a rapid change in properties near a point called the glass transition temperature, where the viscosity of the liquid — its “thickness,” or resistance to flow — becomes very large. But MIT professor Sow-Hsin Chen and his co-researchers have found a different transition point at a temperature about 20 to 30 percent higher, which they call the dynamic crossover temperature - How liquids behave
Børge Svanstrøm Amundsen

"Atlas was permitted the opinion that he was at liberty, if he wished, to drop the Earth and creep away; but this opinion was all that he was permitted" - Franz Kafka
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QIQrrr
 
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Re: Kjemi

Innlegg QIQrrr 17 Jan 2011, 16:35

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University of Arizona, January 14, 2011: Measuring the attractive forces between atoms and surfaces with unprecedented precision, University of Arizona physicists have produced data that could refine our understanding of the structure of atoms and improve nanotechnology. The discovery has been published in the journal Physical Review Letters. Van der Waals forces are fundamental for chemistry, biology and physics. However, they are among the weakest known chemical interactions, so they are notoriously hard to study. This force is so weak that it is hard to notice in everyday life. But delve into the world of micro-machines and nano-robots, and you will feel the force – everywhere. "If you make your components small enough, eventually this van-der-Waals potential starts to become the dominant interaction," said Vincent Lonij, a graduate student in the UA department of physics who led the research as part of his doctoral thesis. "If you make tiny, tiny gears for a nano-robot, for example, those gears just stick together and grind to a halt. We want to better understand how this force works" - UA Physicists Take New Look at the Atom
Børge Svanstrøm Amundsen

"Atlas was permitted the opinion that he was at liberty, if he wished, to drop the Earth and creep away; but this opinion was all that he was permitted" - Franz Kafka
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QIQrrr
 
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Re: Kjemi

Innlegg QIQrrr 07 Apr 2011, 02:41

NASA, April 5, 2011: HOUSTON -- NASA and co-researchers from the United States, South Korea and Japan have found a new mineral named "Wassonite" in one of the most historically significant meteorites recovered in Antarctica in December 1969. The new mineral was discovered within the meteorite officially designated Yamato 691 enstatite chondrite - Scientists Find New Type of Mineral in Historic Meteorite

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Børge Svanstrøm Amundsen

"Atlas was permitted the opinion that he was at liberty, if he wished, to drop the Earth and creep away; but this opinion was all that he was permitted" - Franz Kafka
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Re: Kjemi

Innlegg stian 21 Nov 2011, 05:27

Evt bruksområde til CO2?

http://www.ncbi.nlm.nih.gov/pubmed/21410231

Tricarbonyl rhenium(I) complexes, such as Re(bpy)(CO)(3)Cl where bpy = 2,2'-bipyridyl, have demonstrated superior activity in catalyzing CO(2) reduction in the presence of sacrificial electron donors. We have utilized density functional theory (DFT) to investigate a potential pathway for formate production via a rhenium-hydride insertion mechanism in the presence of triethylamine (TEA). On the basis of prior studies, we re-examined the role of TEA and studied a catalytic cycle for CO(2) reduction in which TEA functions as both the hydrogen atom and the electron donor for reducing CO(2) into formate. The catalytic cycle is found to be exothermic with inclusion of solvation and may be viewed as a two-electron reduction of CO(2) because the net result is a transfer of hydride from TEA to CO(2). In addition, we have identified structures of key intermediates in the CO(2)-reduction process and found that the insertion step has a very modest barrier in acetonitrile. These findings provide a molecular-level understanding to formate production via CO(2) reduction mediated by transition-metal complexes. A theoretical investigation is underway to elucidate the formation of carbon monoxide, another common product in Re-catalyzed CO(2) reduction.


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