Self-assemblies of n-hexadecane and n-hexatricontane on the Au(111) surfaces in their neat liquid or solution have been studied by using scanning tunneling microscopy (STM). Ordered monolayers are observed on the reconstructed Au(111) surfaces, while no overlayer could be observed on the unreconstructed surface at room temperature. The reconstructed surface is found to be perfect for the n-alkanes to self-assemble on it, because the alkane monolayer geometrically matches well to the reconstructed surface. The reconstruction stabilizes the self-assembled monolayer on the Au(111) surface, which facilitates the observation of STM.Highly ordered molecular monolayers at the solid/liquid interfaces play a critical role in many technologically important areas, such as lubrication, adhesion, molecular recognition, and chemical reactions. It is, therefore, crucial to understand the structure of the monolayers so as to understand its role in these processes. Although there are a number of results on monolayers of organic molecules physisorbed on solid surfaces being reported, 1 the role of the substrate lattice parameters, the substrate structures, and defects in the formation of highly ordered monolayers have not yet been well explored. Normal alkanes physisorbed on solid surfaces constitute one of the representative classes of physisorbed systems. Detailed studies of n-alkanes physisorbed on highly oriented pyrolytic graphite (HOPG) surfaces are available. 1-3 However, only a few studies about n-alkanes on substrates other than HOPG have been reported. [4][5][6][7][8] In this paper, we report the scanning tunneling microscopy (STM) studies of the self-assembly phenomenon of n-alkanes at the interfaces between n-alkane solutions and the Au(111) surfaces. Accurate lattice parameters of the alkane monolayers were measured via the self-calibration with the underneath reconstructed stripes of gold. We demonstrate that the reconstruction of the gold plays a key role in the selfassembly of n-alkanes on the Au(111) surfaces.A massive gold single crystal was used in the STM studies. The single crystalline gold bead was made by melting a gold wire in a hydrogen flame. The (111) facet left at the bead surface was used without polishing. The reconstructed surfaces were prepared by carefully annealing in the hydrogen flame. A droplet of the neat n-hexadecane (C 16 H 34 ) or the saturated n-hexatricontane (C 36 H 74 ) in dodecane was then placed on the clean Au-(111) surface. A mechanically cut Pt/Ir tip was immersed into the liquid droplet in the STM observations.On the reconstructed Au(111) surface, the self-assembly of n-alkanes can be easily observed at room temperature in either the neat C 16 H 34 liquid or the C 36 H 74 solution. On the contrary, no ordered alkane monolayer can be observed on the unreconstructed Au(111) surface. Instead, the atomic resolution of the Au(111) lattice can be observed at a given high tunneling current and a low bias voltage, e.g., 5 nA and 20 mV, which demonstrates that the absence of the ordered mo...

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Microbial community proteomics, also termed metaproteomics, is an emerging field within the area of microbiology, which studies the entire protein complement recovered directly from a complex environmental microbial community at a given point in time. Although it is still in its infancy, microbial community proteomics has shown its powerful potential in exploring microbial diversity, metabolic potential, ecological function and microbe-environment interactions. In this paper, we review recent advances achieved in microbial community proteomics conducted in diverse environments, such as marine and freshwater, sediment and soil, activated sludge, acid mine drainage biofilms and symbiotic communities. The challenges facing microbial community proteomics are also discussed, and we believe that microbial community proteomics will greatly enhance our understanding of the microbial world and its interactions with the environment.

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