32 research outputs found

    Finger Probe Array for Topography-Tolerant Scanning Electrochemical Microscopy of Extended Samples

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    Scanning electrochemical microscopy with soft microelectrode array probes has recently been used to enable reactivity imaging of extended areas and to compensate sample corrugation perpendicular to the scanning direction. Here, the use of a new type of microelectrode arrays is described in which each individual microelectrode can independently compensate corrugations of the sample surface. It consists of conventional Pt microelectrodes enclosed in an insulating glass sheath. The microelectrodes are individually fixed to a new holder system by magnetic forces. The concept was tested using a large 3D sample with heights up to 12 ÎĽm specially prepared by inkjet printing. The microelectrodes follow the topography in a constant working distance independently from each other while exerting low pressure on the surface

    Making Graphene-type Material via Polymerization of Porphyrin

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    The synthesis of new graphene-type materials (via polymerization of porphyrin macrocycles) through a simple chemical synthetic pathway (at RT) has been demonstrated. This newly synthesized material can be dispersed in water with an average sheet size of few microns and with single layer thickness. As the porphyrin contains four inner ring nitrogen atoms thus the presented polymeric material will be close analogous of N-doped graphene. Porphyrin as the key component to synthesize layered graphene type continuous 2D structure has never been attempted before. </p

    Crystal Structure, Spectroscopic Investigations, and Physical Properties of the Ternary Intermetallic REPt2Al3 (RE = Y, Dy–Tm) and RE2Pt3Al4 Representatives (RE = Tm, Lu)

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    The REPt2Al3 compounds of the late rare-earth metals (RE = Y, Dy&ndash;Tm) were found to crystallize isostructural. Single-crystal X-ray investigations of YPt2Al3 revealed an orthorhombic unit cell (a = 1080.73(6), b = 1871.96(9), c = 413.04(2) pm, wR2 = 0.0780, 942 F2 values, 46 variables) with space group Cmmm (oC48; q2pji2hedb). A comparison with the Pearson database indicated that YPt2Al3 forms a new structure type, in which the Pt and Al atoms form a [Pt2Al3]&delta;&minus; polyanion and the Y atoms reside in the cavities within the framework. Via a group-subgroup scheme, the relationship between the PrNi2Al3-type structure and the new YPt2Al3-type structure was illustrated. The compounds with RE = Dy&ndash;Tm were characterized by powder X-ray diffraction experiments. While YPt2Al3 is a Pauli-paramagnet, the other REPt2Al3 (RE = Dy&ndash;Tm) compounds exhibit paramagnetic behavior, which is in line with the rare-earth atoms being in the trivalent oxidation state. DyPt2Al3 and TmPt2Al3 exhibit ferromagnetic ordering at TC = 10.8(1) and 4.7(1) K and HoPt2Al3 antiferromagnetic ordering at TN = 5.5(1) K, respectively. Attempts to synthesize the isostructural lutetium compound resulted in the formation of Lu2Pt3Al4 (Ce2Ir3Sb4-type, Pnma, a = 1343.4(2), b = 416.41(8), c = 1141.1(2) pm), which could also be realized with thulium. The structure was refined from single-crystal data (wR2 = 0.0940, 1605 F2 values, 56 variables). Again, a polyanion with bonding Pt&ndash;Al interactions was found, and the two distinct Lu atoms were residing in the cavities of the [Pt3Al4]&delta;&ndash; framework. X-ray photoelectron spectroscopy (XPS) measurements were conducted to examine the electron transfer from the rare-earth atoms onto the polyanionic framework

    Nanoporous copper ribbons prepared by chemical dealloying of a melt-spun ZnCu alloy

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    Dealloying is a powerful and versatile method to fabricate three-dimensional nanoporous (np) materials with high surface area. In this work, we investigated the dealloying processes of Zn80Cu20 alloy ribbons in acidic and alkaline environments. Our results show that the nanostructure can be controlled by varying the nature of electrolyte solution, pH value, dealloying time, and temperature. In acidic media, the presence of chloride ions enhances the Cu surface mobility, leading to a faster coarsening and growth of ligaments during the dealloying process over time. In contrast, the surface diffusivity of Cu atoms in alkaline media is three orders lower than that in acid and results in a remarkably smaller ligament size due to the formation of Cu (hydr)oxide surface species. Cross-section analysis indicates that the dealloying process is largely controlled by interfacial processes. Interestingly, local Zn-rich regions were found near the surface in np-Cu ribbons dealloyed in 0.1 M HCl. This comprehensive study shows the influence of dealloying conditions on the morphology and residual Zn content of np-Cu ribbons as a model system for fabricating bicontinuous ligament-pore network materials with tailored structural and chemical properties for applications in electrochemical synthesis, sensors, and catalysis.Postprint (published version

    The L-Cysteine Desulfurase NFS1 Is Localized in the Cytosol where it Provides the Sulfur for Molybdenum Cofactor Biosynthesis in Humans

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    <div><p>In humans, the L-cysteine desulfurase NFS1 plays a crucial role in the mitochondrial iron-sulfur cluster biosynthesis and in the thiomodification of mitochondrial and cytosolic tRNAs. We have previously demonstrated that purified NFS1 is able to transfer sulfur to the C-terminal domain of MOCS3, a cytosolic protein involved in molybdenum cofactor biosynthesis and tRNA thiolation. However, no direct evidence existed so far for the interaction of NFS1 and MOCS3 in the cytosol of human cells. Here, we present direct data to show the interaction of NFS1 and MOCS3 in the cytosol of human cells using Förster resonance energy transfer and a split-EGFP system. The colocalization of NFS1 and MOCS3 in the cytosol was confirmed by immunodetection of fractionated cells and localization studies using confocal fluorescence microscopy. Purified NFS1 was used to reconstitute the lacking molybdoenzyme activity of the <i>Neurospora crassa nit-1</i> mutant, giving additional evidence that NFS1 is the sulfur donor for Moco biosynthesis in eukaryotes in general.</p> </div
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