Morphology of IPN-like systems consisting of polyethylene and vinyl polymer

The morphology of an interpenetrating network-like (IPN-like) system consisting of polyethylene (PE) and polystyrene (PS) is compared with an IPN system consisting of PE and polymethacrylate copolymers with different lengths of alkyl groups. In the presence of dodecyl methacrylate (DMA) units in the copolymer network of the IPN-like system, increased homogeneity of the interphase was observed.     

Combined experimental and theoretical investigation of the premartensitic transition in Ni2MnGa

Ultraviolet-photoemission (UPS) measurements and supporting specific-heat, thermal-expansion, resistivity, and magnetic-moment measurements are reported for the magnetic shape-memory alloy Ni2MnGa over the temperature range 100T(PM) is due to the Ni d minority-spin electrons. Below T(M) this peak disappears, resulting in an enhanced density of states at energies around 0.8 eV. This enhancement reflects Ni d and Mn d electronic contributions to the majority-spin density of states.     

Reducing the molecule-substrate coupling in C60-based nanostructures by molecular interactions

Codeposition of C60 and the three-dimensional molecular hydrocarbon 1,3,5,7-tetraphenyladamantane (TPA) on Au(111) leads to the spontaneous formation of molecular nanostructures in which each fullerene is locked into a specific orientation by three surrounding TPA. Scanning tunneling spectroscopy shows that the electronic coupling of C60 with the surface is significantly reduced in these nanostructures, enhancing the free-molecule properties. As evidenced by density functional theory simulations, the nanostructures are stabilized by 18 local electrostatic forces between C60 and TPA, resulting in a lifting of the C60 cage from the surface.     

Shape‐directed platinum nanoparticle synthesis: nanoscale design of novel catalysts

Platinum‐based catalytic materials have received significant attention, particularly in the shape and size control of faceted materials for catalysis. More recently, there has been a rapid increase in the number of reports of successful preparations in this field; however, a fundamental understanding of controlled growth towards catalytic material design is essential for future implementation and broad application. In this review, we provide an overview of the recent findings reported since 2009, focusing on methods for shape control as well as the effects of exposed surface facets on select catalytic reactions. Copyright © 2013 John Wiley & Sons, Ltd.     

Über Humussäuren

Zusammenfassung Der 1. Teil der vorliegenden Untersuchung befa?t sich mit der Bestimmung des ?quivalentgewichtes einiger aus mitteldeutscher Braunkohle gewonnener Humuss?uren. Das ?quivalentgewicht wurde für die wasserfreien Pr?parate im Mittel zu 190 gefunden. Im 2. Teil der Arbeit wurde die Einwirkung überschüssiger Natronlauge auf Humuss?uren untersucht. Dabei wurde gefunden, da? sowohl bei h?herer Temperatur als auch bei Zimmertemperatur eine Zersetzung der Humuss?uren stattfindet, und zwar entstehen dabei ein oder mehrere wasserl?sliche Zersetzungsprodukte mit sauren Eigenschaften. Diese Resultate wurden durch umfangreiche konduktometrische Messungen gewonnen. Nachdem wir die Frage nach der Best?ndigkeit von Natriumhumatl?sungen gekl?rt haben, halten wir es auf Grund des vorliegenden Versuchsmaterials für m?glich, Molekulargewichtsbestimmungen von Humuss?uren, Humins?uren und Hymatomelans?uren aus der Diffusion ihrer Natriumsalzl?sungen vorzunehmen. Versuche darüber sind von uns in Angriff genommen worden.     

How to confirm identified toxicants in effect-directed analysis

Due to the production and use of a multitude of chemicals in modern society, waters, sediments, soils and biota may be contaminated with numerous known and unknown chemicals that may cause adverse effects on ecosystems and human health. Effect-directed analysis (EDA), combining biotesting, fractionation and chemical analysis, helps to identify hazardous compounds in complex environmental mixtures. Confirmation of tentatively identified toxicants will help to avoid artefacts and to establish reliable cause–effect relationships. A tiered approach to confirmation is suggested in the present paper. The first tier focuses on the analytical confirmation of tentatively identified structures. If straightforward confirmation with neat standards for GC–MS or LC–MS is not available, it is suggested that a lines-of-evidence approach is used that combines spectral library information with computer-based structure generation and prediction of retention behaviour in different chromatographic systems using quantitative structure–retention relationships (QSRR). In the second tier, the identified toxicants need to be confirmed as being the cause of the measured effects. Candidate components of toxic fractions may be selected based, for example, on structural alerts. Quantitative effect confirmation is based on joint effect models. Joint effect prediction on the basis of full concentration–response plots and careful selection of the appropriate model are suggested as a means to improve confirmation quality. Confirmation according to the Toxicity Identification Evaluation (TIE) concept of the US EPA and novel tools of hazard identification help to confirm the relevance of identified compounds to populations and communities under realistic exposure conditions. Promising tools include bioavailability-directed extraction and dosing techniques, biomarker approaches and the concept of pollution-induced community tolerance (PICT). Figure Toxicity confirmation in EDA as a tiered approach     

Anchoring of histidine-tagged proteins to molecular printboards: self-assembly, thermodynamic modeling, and patterning

In this paper the multivalent binding of hexahistidine (His6)-tagged proteins to beta-cyclodextrin (beta-CD) self-assembled monolayers (SAMs) by using the nickel(II) complex of a hetero-divalent orthogonal adamantyl nitrilotriacetate linker (4) is described. Nonspecific interactions were suppressed by using monovalent adamantyl-hexa(ethylene glycol) derivative 3. With the mono-His6-tagged maltose binding protein (His6-MBP), thermodynamic modeling based on surface plasmon resonance (SPR) titration data showed that the MBP molecules in solution were linked, on average, to Ni.4 in 1:1 stoichiometry. On the surface, however, the majority of His(6)-MBP was complexed to surface-immobilized beta-CDs through three Ni.4 complexes. This difference is explained by the high effective beta-CD concentration at the surface and is a new example of supramolecular interfacial expression. In a similar adsorption scheme, SPR proved that the alpha-proteasome could be attached to beta-CD SAMs in a specific manner. Patterning through microcontact printing of (His6)4-DsRed-fluorescent timer (DsRed-FT), which is a tetrameric, visible autofluorescent protein, was carried out in the presence of Ni.4 Fluorescence measurements showed that the (His6)4-DsRed-FT is bound strongly through Ni.4 to the molecular printboard.