One popular model suggests that life on Earth originates from a prebiotic soup, which is the idea that a large amount of different elements spontaneously came together in a pool to form basic organic moleculars. These basic organic moleculars are believed to have then condensed and reacted to form more complex organic moleculars and then eventually formed the original life. In the process of chemical evolution, the conversion of inorganic compounds to small organic moleculars is the first and indispensable step for the origin of life. Scientists have designed many experiments that could provide evidence in support of the theory of the prebiotic soup. In these experiments, small moleculars of CO 2 , CO, CH 4 or CH 3 SH have ever been taken as the building blocks for the synthesis of organic molecules. When introducing H 2 S, N 2 , NH 3 et al., amino acids, nucleotides and other possible monomers, nonenzymatically condensing to form oligomeric products, could be synthesized. Meanwhile, pyrite, coprecipitated (Ni,Fe)S, Fe 3 O 4 as well as some other minerals might take part in the processes of selection, concentration and energy supplement, especially of the emergence of chirality preference in the extant amino acids and sugars in living organisms. Herein recent progress made in the research into the prebiotic soup theory of the origin of life is reviewed. Finally, after discussion of the possible existence of carbon nanotubes in primitive earth, their morphology similarity, affinity and selectivity with biology moleculars, it is proposed that carbon nanotubes might play a significant role in the origin of life.
Epitaxial thin films of PrBa 2 (Cu 0.8 Al 0.2) 3 O 7 have been vacuum deposited by rf sputtering on the LaAlO 3 substrates. Though electrically much more resistive, these Al-substituted films are all of orthorhombic structure and epitaxial quality on various oxide substrates, much like YBa 2 Cu 3 O 7 and PrBa 2 Cu 3 O 7 grown under similar conditions. The samples appeared to be shiny and dark as observed with the naked eye, but their electrical resistivity, (T), ranged from ϳ1 ⍀ cm at room temperature to about six orders of magnitude higher at Tϳ30 K. From the (T) functional for both the target and the films, which, by and large, follows Mott's T Ϫ1/4 law with their own relevant material constants, we believe that the mechanism of electrical conduction was mainly through variable range hopping. This suggests that the substitution of Al has caused extensive localization of charge carriers. The localization radius is ϳ0.2 nm while the hopping distance is ϳ3-9 nm.
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