Additive Effects of LiBH₄ and ZrCoH₃ on the Hydrogen Sorption of the Li-Mg-N‑H Hydrogen Storage System

LiBH₄ is an effective catalyst for the hydrogen sorption of the Li-Mg-N-H storage system. A combination of LiBH₄ with ZrCoH₃ was reported to be catalytically more effective. In this work, materials doped with LiBH₄ or ZrCoH₃ or a combination of ZrCoH₃ and LiBH₄ were characterized both in the as-prepared and in the cycled states. A comparison of the metathesis conversion, thermal behavior, kinetics, and phase evolution induced by H₂ cycling suggests that the two components function additively. While LiBH₄ facilitates the metathesis conversion in the first cycle and enhances kinetics during H₂ cycling by forming a quaternary complex hydride, ZrCoH₃ has at least a pulverizing effect in the material. The chemical environment and near order of the individual atoms of Zr and Co as well as the structural parameters of ZrCoH₃ were investigated by X-ray absorption and found to be unchanged during H₂ cycling

Monolithic Integration of a Silicon Nanowire Field-Effect Transistors Array on a Complementary Metal-Oxide Semiconductor Chip for Biochemical Sensor Applications

We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring <i>I</i>–<i>V</i> curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized nanowire FETs

Uranium Redox Transformations after U(VI) Coprecipitation with Magnetite Nanoparticles

Uranium redox states and speciation in magnetite nanoparticles coprecipitated with U­(VI) for uranium loadings varying from 1000 to 10 000 ppm are investigated by X-ray absorption spectroscopy (XAS). It is demonstrated that the U M₄ high energy resolution X-ray absorption near edge structure (HR-XANES) method is capable to clearly characterize U­(IV), U­(V), and U­(VI) existing simultaneously in the same sample. The contributions of the three different uranium redox states are quantified with the iterative transformation factor analysis (ITFA) method. U L₃ XAS and transmission electron microscopy (TEM) reveal that initially sorbed U­(VI) species recrystallize to nonstoichiometric UO_2+<i>x</i> nanoparticles within 147 days when stored under anoxic conditions. These U­(IV) species oxidize again when exposed to air. U M₄ HR-XANES data demonstrate strong contribution of U­(V) at day 10 and that U­(V) remains stable over 142 days under ambient conditions as shown for magnetite nanoparticles containing 1000 ppm U. U L₃ XAS indicates that this U­(V) species is protected from oxidation likely incorporated into octahedral magnetite sites. XAS results are supported by density functional theory (DFT) calculations. Further characterization of the samples include powder X-ray diffraction (pXRD), scanning electron microscopy (SEM) and Fe 2p X-ray photoelectron spectroscopy (XPS)

2,6-Bis(5-(2,2-dimethylpropyl)-1<i>H</i>-pyrazol-3-yl)pyridine as a Ligand for Efficient Actinide(III)/Lanthanide(III) Separation

The N-donor complexing ligand 2,6-bis­(5-(2,2-dimethylpropyl)-1<i>H</i>-pyrazol-3-yl)­pyridine (C5-BPP) was synthesized and screened as an extracting agent selective for trivalent actinide cations over lanthanides. C5-BPP extracts Am­(III) from up to 1 mol/L HNO₃ with a separation factor over Eu­(III) of approximately 100. Due to its good performance as an extracting agent, the complexation of trivalent actinides and lanthanides with C5-BPP was studied. The solid-state compounds [Ln­(C5-BPP)­(NO₃)₃(DMF)] (Ln = Sm­(III), Eu­(III)) were synthesized, fully characterized, and compared to the solution structure of the Am­(III) 1:1 complex [Am­(C5-BPP)­(NO₃)₃]. The high stability constant of log β₃ = 14.8 ± 0.4 determined for the Cm­(III) 1:3 complex is in line with C5-BPP’s high distribution ratios for Am­(III) observed in extraction experiments