Elucidating the Iron-Based Ionic Liquid [C4py][FeCl4]: Structural Insights and Potential for Nonaqueous Redox Flow Batteries

In this study, a low-melting organic-inorganic crystalline ionic liquid compound, N-butyl pyridinium tetrachlorido ferrate (III) is described. The material can easily be synthesized using a one-pot approach in an ionic liquid medium. Single-crystal X-ray diffraction confirms that the basic inorganic block is [FeCl₄]⁻, which is counterbalanced by an N-butyl pyridinium cation. The compound exhibits a melting point of 37.6 °C by differential scanning calorimetry, which is among the lowest values for a pyridinium-based metal-containing ionic liquid. The material shows promising electrochemical behavior at room temperature in both aqueous and nonaqueous solvents, and at elevated temperatures in its pure liquid state. Given its appreciable solubility in both water and acetonitrile, the compound can act as a redox-active species in a supporting electrolyte for redox flow battery applications. These classes of low-melting ionic solids with long-range order and interesting electrochemical applications are potential candidates for a range of green energy storage and harvesting systems.     

Classical analog of electromagnetically induced absorption in plasmonics

The ability to manipulate the phase shift between two resonantly coupled plasmonic oscillators in a controlled fashion has been unavailable up to now. Here we present a strategy to overcome this limitation by employing the benefits of near-field coupling on the one hand and retardation effects due to far-field coupling on the other hand. We theoretically and experimentally demonstrate that in the intermediate regime the coupling of a broad dipolar to a narrow dark quadrupolar plasmon resonance is possible while simultaneously allowing for a retardation-induced phase shift. This leads to constructive interference and enhanced absorption. The observed phenomenon can thus be termed a classical analog of electromagnetically induced absorption.     

Protein‐based stable isotope probing (protein‐SIP) in functional metaproteomics

The community phenotype as the sum of molecular functions of organisms living in consortia strongly depends on interactions within these communities. Therefore, the analyses of the most significant molecules in terms of the phenotype, the proteins, have to be performed on samples without disrupting the meta‐species environment. Due to the increasing genomic information, proteins provide insights into a potential molecular function and the phylogenetic structure of the community. Unfortunately, the lists of identified proteins are often based first on the technical capacity of the used methods or instruments, and second on the interpretation of them by the assignment of molecular functions to proteins in databases. Especially in non‐model organisms the functions of many proteins are often not known and an increasing number of studies indicate a significant amount of uncertainty. To decrease the dependency on assumptions and to enable functional insights by metaproteome approaches, the metabolic labeling from an isotopically labeled substrate can be used. Since the metabolites deriving from the substrate are very rarely species‐specific, the incorporation of the stable isotope into proteins can be used as a surrogate marker for metabolic activity. The degree of incorporation can be determined accurately on the peptide level by mass spectrometry; additionally, the peptide sequence provides information on the metabolic active species. Thereby, protein‐stable isotope probing (protein‐SIP) adds functional information to metaproteome approaches. The classical metaproteome approaches will be reviewed with an emphasis on their attempts towards functional interpretation. The gain from functional insights into metaproteomics by using metabolic labeling of stable isotopes of carbon, nitrogen, and sulfur is reviewed with a focus on the techniques of measurement, calculation of incorporation and data processing. © 2012 Wiley Periodicals, Inc. Mass Spec Rev 31:683–697, 2012     

Monochromator-Based Absolute Calibration of Radiation Thermometers

A monochromator integrating-sphere-based spectral comparator facility has been developed to calibrate standard radiation thermometers in terms of the absolute spectral radiance responsivity, traceable to the PTB cryogenic radiometer. The absolute responsivity calibration has been improved using a 75 W xenon lamp with a reflective mirror and imaging optics to a relative standard uncertainty at the peak wavelength of approximately 0.17 % (k = 1). Via a relative measurement of the out-of-band responsivity, the spectral responsivity of radiation thermometers can be fully characterized. To verify the calibration accuracy, the absolutely calibrated radiation thermometer is used to measure Au and Cu freezing-point temperatures and then to compare the obtained results with the values obtained by absolute methods, resulting in T ? T ₉₀ values of +52 mK and ?50 mK for the gold and copper fixed points, respectively.     

Photoreduction of a crystalline Au(III) complex: A solidstate approach to metallic nanostructures

Gold platelets with a nanometer thickness and a width of up to 15 μm have been fabricated by photoreduction of Au(III) within a layered, crystalline gold complex. Particle shape selection (large spheres vs. platelets) is largely controlled by the sample temperature, which varies with the UV lamp-sample distance: at short distances the sample melts and only micrometer-sized spheres form, at intermediate distances platelets and spheres form, and at distances over ca. 40 cm, mostly platelets form. The particles can be stabilized with thiols and extracted from the organic matrix.