We report the observation of a new type of charge-density wave (CDW) in the large magnetic-moment rare-earth intermetallic compound, Er 5 Ir 4 Si 10 , which then orders magnetically at low temperatures. Single crystal x-ray diffraction shows the development of a 1D incommensurate CDW at 155 K, which then locks into a purely commensurate state below 55 K. The well-localized Er 31 moments are antiferromagnetically ordered below 2.8 K. We observe very sharp anomalies in the specific heat at 145 and 2.8 K, signifying the bulk nature of these transitions. Our data suggest the coexistence of strongly coupled CDW with local-moment antiferromagnetism in Er 5 Ir 4 Si 10 . PACS numbers: 71.45.Lr, 75.20.Hr, 71.20.Lp Charge-density-wave (CDW) transitions occur in lowdimensional solids where it is possible to achieve nesting of Fermi surfaces that leads to the appearance of a periodic lattice distortion with an accompanying energy gap D [1-4]. These materials show striking nonlinear and anisotropic properties as well as unusual elastic and dynamic behaviors: This makes them an appealing field for experimental and theoretical studies on Fermi surface gapping and electron-phonon coupling. A number of such systems have been previously studied, including quasi-1D organic salts (e.g., TTF-TCNQ) [5] and inorganic chain compounds (e.g., NbSe 3 ) [2]. Here a Peierls-Fröhlich-type [4] phase transformation is observed at a finite temperature T CDW : Above this temperature the coupled electronphonon system is unstable with respect to a deformation of wave vector q 2k F . Below T CDW , the ground state is characterized by a gap in the single-particle excitation spectrum.Although many of the properties of these quasi-1D compounds could be understood within the framework of this continuous phase transition with weak electronphonon and interchain coupling, the thermodynamic behavior of the CDW transition in compounds such as TaSe 2 [6] and the blue bronzes [3] requires a description beyond the weak-coupling model. McMillan [7], using strong electron-phonon coupling and small interchain correlation lengths, was able to provide a microscopic theory, which has given a semiquantitative explanation for the peculiar behavior of these latter systems, like their specific heat jumps and D͞T CDW ratios. In recent years interest in this area has focused on detailed investigation of these conventional CDW systems. However, in order to probe the theory further and search for novel CDW behaviors, especially those involving the interplay with magnetism, new classes of materials are needed. To the best of our knowledge there does not exist a local-moment magnet (mediated by the RKKY interaction between the f and conduction electrons) exhibiting a CDW.We have begun a quest for new CDW systems in intermetallic rare-earth (RE) compounds and found indications in the literature [8][9][10] for such behavior in a series of RE 5 Ir 4 Si 10 materials. Polycrystalline samples showed anomalies in the resistivity above 20 K, which were tentatively attributed to CD...

Understanding the electrochemical behavior of Pt at the solid/liquid interface is of significant importance for the development of efficient electrochemical devices, such as fuel cells and water electrolyzers. In this work, the evolution of the surface morphology of a polycrystalline platinum under potential cycling conditions was investigated by in situ electrochemical atomic force microscopy (EC-AFM). After 50 cycles between 0.05 and 1.8 V in 0.1 M HSO, the Pt surface is coarsened and nanoparticles of several nanometers appear on the surface. The critical upper and lower potentials for the formation of nanoparticles are found to be 1.8 and 0.8 V, respectively. The in situ AFM observation coupled with Cyclic Voltammerty reveals the periodic disappearance and reappearance of the nanoparticles, based on which the formation of nanoparticles is attributed to the deposition of dissolved Pt from solution, and a model for the nanoparticle formation is proposed. While the formation of a thick oxide layer is a prerequisite, the reduction process is found to have a strong influence on Pt nanoparticle formation as well. This investigation provides a visualization of the Pt electrode surface under electrochemical control in a large potential window, enabling a broader understanding of the Pt electrode roughening mechanisms.

In our postgenomic era, understanding of protein‐protein interactions by characterizing the structure of the corresponding protein complex is becoming increasingly important. An important problem is that many protein complexes are only stable for a few minutes. Dissociation will occur when using the typical, time‐consuming purification methods such as tandem affinity purification and multiple chromatographic separations. Therefore, there is an urgent need for a quick and efficient protein‐complex purification method for 3D structure characterization. The graphene oxide (GO)·streptavidin complex is prepared via a GO·biotin·streptavidin strategy and used for affinity purification. The complex shows a strong biotin recognition capability and an excellent loading capacity. Capturing biotinylated DNA, fluorophores and Au nanoparticles on the GO·streptavidin complexes demonstrates the usefulness of the GO·streptavidin complex as a docking matrix for affinity purification. GO shows a high transparency towards electron beams, making it specifically well suited for direct imaging by electron microscopy. The captured protein complex can be separated via a filtration process or even via on‐grid purification and used directly for single‐particle analysis via cryo‐electron microscopy. Therefore, the purification, sample preparation, and characterization are rolled into one single step.

A novel method is described for preparing single walled carbon nanotube (SWNT)−streptavidin complexes via the biotin−streptavidin recognition. The complex shows stability in 18 days, strong biotin recognition capability, and excellent loading capacity (about 1 streptavidin tetramer per 20 nm of SWNT). Capturing biotinylated DNA, fluorophores, and Au nanoparticles (NPs) on the SWNT−streptavidin complexes demonstrates their usefulness as a docking matrix, for instance for electron microscopy studies, a technique requiring a virtually electron transparent support.