Synthese und Struktur einer neuen Form von CuNdW2O8: β-CuNdW2O8

Synthesis and Structure of a New Form of CuNdW₂O₈: β-CuNdW₂O₈ Single crystals of an unknown form of CuNdW₂O₈ were prepared and investigated by X-ray diffractometer technique [space group C? P₁; a = 6.1330; b = 6.0760; c = 5.0190 Å; α = 111.79°; β = 93.24°; γ = 111.20°; Z = 1]. β-CuNdW₂O₈ represents a new structure type characterized by WO₆ octahedral chains and O? Cu? O dumbbells. Its structure is discussed in respect to other copper tungstates.     

Quantitative three-dimensional microstructure of a solid oxide fuel cell cathode

Solid oxide fuel cells (SOFCs) are being actively developed world wide for clean and efficient electrical generation from fuels such as natural gas, hydrogen, coal, and gasoline. The cathode in state of the art SOFCs is typically a porous composite of electronically-conducting La_1?xSr_xMnO₃ (LSM) and ionically-conducting Y₂O₃-stabilized ZrO₂ (YSZ) that facilitates the critical oxygen reduction reaction. Here we describe the three-dimensional characterization and quantification of key structural parameters from an LSM-YSZ cathode, using imaging and volume reconstruction based on focused ion beam – scanning electron microscopy. LSM-YSZ-pore three-phase boundaries (TPBs) were identified. Approximately 1/3 of the TPBs were found to be electrochemically inactive, as they were on isolated LSM particles, yielding an active TPB density of 4.9 μm^?2. Cathode electrochemical modeling, which included a measured YSZ tortuosity of 3.4, yielded an effective TPB resistance of ≈2.5 × 10⁵ Ω cm at 800 °C.     

New limit on time-reversal violation in beta decay

We report the results of an improved determination of the triple correlation DP·(p(e)×p(v)) that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the standard model. Our result is D=[-0.96±1.89(stat)±1.01(sys)]×10(-4). The corresponding phase between gA and gV is ?AV=180.013°±0.028° (68% confidence level). This result represents the most sensitive measurement of D in nuclear β decay.     

Manipulating energy landscapes to tune ordering in biotemplated nanoparticle arrays

Two-dimensional non-close-packed crystals of the protein streptavidin, grown on phospholipid membranes, can serve as nanoscale templates capable of directing the formation of ordered nanoparticle arrays through site-specific electrostatic adsorption. Here we examine the effects of both interparticle and nanoparticle/lipid membrane electrostatic interactions on the degree of structural order exhibited by the templated nanoparticle array. Interparticle electrostatic repulsion is shown to have only marginal influence on nanoparticle ordering. In contrast, the degree of order exhibited by the templated array can be tuned by controlling the charge on the lipid membrane. Analysis of the local and global structure of arrays generated with negatively charged gold nanoparticles (～6 nm) indicate improved long-range order when the lipid membrane supporting the protein crystal is derived from cationic lipid molecules as opposed to zwitterionic phospholipids. Furthermore, as nanoparticle size is reduced (～3 nm), the presence of a charged lipid membrane is found to be essential, as smaller particles do not adhere to streptavidin crystals grown on zwitterionic membranes. These findings demonstrate that the composition of the lipid support can influence the efficacy of directed-assembly processes which utilize protein templates and are important results toward enhancing control over bottom-up nanofabrication applications.     

Zur Kristallstruktur von α-TlSmW2O8

Single crystals of -TlSm(WO₄)₂ were examined by X-ray diffractometer technique (space group C _2h ⁶ -C2/c;a=10.770,b=10.597,c=7.597 Å, =130.09°,Z=4). The coordination of W⁶⁺, Sm³⁺ and Tl⁺ are discribed and discussed.-TlSm(WO₄)₂ is isotypic to -KY(WO₄)₂.

     

Phase stability and lithium loading capacity in a liquid scintillation cocktail

Journal of Radioanalytical and Nuclear Chemistry - Liquid scintillation cocktails loaded with neutron capture agents such as 6Li are used in both neutron and neutrino detectors. For detectors...     

Time reversal and the neutron

We have measured the triple correlation $D\langle\vec J_n\rangle/J_n\cdot (\vec\beta_e\times\hat p_\nu)$ with a polarized cold-neutron beam (Mumm et al., Phys Rev Lett 107:102301, 2011; Chupp et al., Phys Rev C 86:035505, 2012). A non-zero value of D can arise due to parity-even-time-reversal-odd interactions that imply CP violation. Final-state effects also contribute to D at the level of 10^???5 and can be calculated with precision of 1 % or better. The D coefficient is uniquely sensitive to the imaginary part of the ratio of axial-vector and vector beta-decay amplitudes as well as to scalar and tensor interactions that could arise due to beyond-Standard-Model physics. Over 300 million proton-electron coincidence events were used in a blind analysis with the result D?=?[???0.94±1.89 (stat)±0.97(sys)]×10^???4. Assuming only vector and axial vector interactions in beta decay, our result can be interpreted as a measure of the phase of the axial-vector coupling relative to the vector coupling, $\phi_{\rm AV}= 180.012^\circ \pm 0.028^\circ$ . This result also improves constrains on certain non-VA interactions.     

Untersuchung von Milch und Milchprodukten

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