Supernova Inelastic Neutrino-Nucleus Cross Sections from High-Resolution Electron Scattering Experiments and Shell-Model Calculations

Highly precise data on the magnetic dipole strength distributions from the Darmstadt electron linear accelerator for the nuclei 50Ti, 52Cr and 54Fe are dominated by isovector Gamow-Teller-like contributions and can therefore be translated into inelastic total and differential neutral-current neutrino-nucleus cross sections at supernova neutrino energies. The results agree well with large-scale shell-model calculations, validating this model.Comment: 5 pages, 4 figures, RevTeX 4, version accepted in Phys. Rev. Letter

Investigation of teacher’s health in a mixed-methods-design study using videography

Basierend auf dem Systemischen Anforderungs-Ressourcen-Modell (Becker, 2006) wurden in dieser Studie (1) im Mixed-Methods-Design die Gesundheit von 19 Lehrern untersucht, (2) Anforderungen und Ressourcen im Unterricht mittels Videografien erhoben und (3) in einer fallkontrastierenden Typenbildung trianguliert. Es zeigte sich, dass neben einem engagierten und disziplinierten Schülerverhalten, die Klassenführung - kombiniert mit einer hohen Sozialkompetenz - sowie die verwendeten Unterrichtsmethoden wichtige Ressourcen für Lehrer darstellen. (DIPF/Orig.)In this study the systemic demands-resources model (Becker, 2006) was applied (1) to investigate the health condition of teachers using a mixed-methods-design, (2) to ascertain the demands and resources during lessons using videography and (3) to triangulate the data in a case contrasting typification. It was observed that, in addition to the committed and disciplined behavior of students, classroom management combined with high social competence and the applied teaching methods represent crucial resources for teachers. (DIPF/Orig.

Novel liquid–liquid extraction and ion exchange processes for hydrometallurgical recovery of lithium, nickel and cobalt from lithium-ion battery waste leachate

Hydrometallurgy is a promising technology for recovering valuable key components such as Li, Ni and Co from spent lithium-ion batteries. In this thesis, flowsheets of alternative processing routes were developed to yield high-purity products with high recovery yields. Two hydrometallurgical separation processes were studied: i) the direct extraction of Li from lithium-ion battery waste leachate (LIBWL) and ii) the recovery and purification of a Li+Ni+Co mixture using continuous ion exchange. Batch equilibrium experiments and McCabe–Thiele analyses were carried out to develop a new solvent extraction process to directly recover Li from LIBWL. The employed extraction system, TBP/FeCl3 in kerosene with AlCl3 as a supplementary chloride source, selectively extracted 87.7% of Li in a single extraction stage. The novel processing route yielded 99.1% pure Li-stripping liquor with a Li concentration of 13.95 g L-1. The direct extraction of Li guarantees high recovery yields and is a viable alternative for the recovery of Li from LIBWL. The chelating resin Lewatit® MDS TP 260 with aminomethylphosphonic functional group selectively removed the impurities Al, Cu, Fe and Mn from LIBWL. Single-column experiments were carried out to design a continuous multicolumn ion exchange process. The continuously operated laboratory-scale SMB-type configuration processed 1.64 L (L h)-1 of leachate to yield 34.04 g (L h)-1 of pure Li+Ni+Co raffinate. Very high recovery yields of 100%, 99.2% and 96.9% for Li, Ni and Co were achieved and demonstrated superior performance over conventional state-of-the-art single-column ion exchange, solvent extraction and precipitation processes. Overall, the developed flowsheets allow for the processing of high-purity products and guarantee high recovery yields in lithium-ion battery (LIB) recycling. Future research could further explore novel alternative processing routes through clever choice of the chemical extraction system and the separation process configuration to overcome the conventional selectivity order and maintain high recovery yields in difficult hydrometallurgical separations

Orbital M1 versus E2 strength in deformed nuclei: A new energy weighted sum rule

Within the unified model of Bohr and Mottelson we derive the following linear energy weighted sum rule for low energy orbital 1$^+$ excitations in even-even deformed nuclei S_{\rm LE}^{\rm lew} (M_1^{\rm orb}) \cong (6/5) \epsilon (B(E2; 0^+_1 \rightarrow 2_1^+ K=0)/Z e^2^2) \mu^2_N with B(E2) the E2 strength for the transition from the ground state to the first excited state in the ground state rotational band, $$ the charge r.m.s. radius squared and $\epsilon$ the binding energy per nucleon in the nuclear ground state. It is shown that this energy weighted sum rule is in good agreement with available experimental data. The sum rule is derived using a simple ansatz for the intrinsic ground state wave function that predicts also high energy 1$^+$ strength at 2$\hbar \omega$ carrying 50\% of the total $m_1$ moment of the orbital M1 operator.Comment: REVTEX (3.0), 9 pages, RU924

Level density and gamma strength function in 162-Dy from inelastic 3-He scattering

Complementary measurements have been performed for the level density and gamma strength function in 162-Dy using inelastic 3-He scattering. Comparing these results to previous measurements using the 163-Dy(3-He,alpha) reaction, reveals that the measured quantities above 1.5 MeV do not depend significantly on the nuclear reaction chosen.Comment: 15 pages, including 7 figure

Level density and thermal properties in rare earth nuclei

A convergent method to extract the nuclear level density and the gamma-ray strength function from primary gamma-ray spectra has been established. Thermodynamical quantities have been obtained within the microcanonical and canonical ensemble theory. Structures in the caloric curve and in the heat capacity curve are interpreted as fingerprints of breaking of Cooper pairs and quenching of pairing correlations. The strength function can be described using models and common parameterizations for the E1, M1 and pygmy resonance strength. However, a significant decrease of the pygmy resonance strength at finite temperatures has been observed.Comment: 15 pages including 8 figures. Proceedings article for the conference Nuclear Structure and Related Topics, Dubna, Russia, June 6-10, 200

Extended M1 sum rule for excited symmetric and mixed-symmetry states in nuclei

A generalized M1 sum rule for orbital magnetic dipole strength from excited symmetric states to mixed-symmetry states is considered within the proton-neutron interacting boson model of even-even nuclei. Analytic expressions for the dominant terms in the B(M1) transition rates from the first and second $2^+$ states are derived in the U(5) and SO(6) dynamic symmetry limits of the model, and the applicability of a sum rule approach is examined at and in-between these limits. Lastly, the sum rule is applied to the new data on mixed-symmetry states of 94Mo and a quadrupole d-boson ratio $nd(0^+_1)/nd(2^+_2) \approx 0.6$ is obtained in a largely parameter-independent wayComment: 19 pages, 3 figures, Revte

The mycotoxin phomoxanthone A disturbs the form and function of the inner mitochondrial membrane.

Mitochondria are cellular organelles with crucial functions in the generation and distribution of ATP, the buffering of cytosolic Ca2+ and the initiation of apoptosis. Compounds that interfere with these functions are termed mitochondrial toxins, many of which are derived from microbes, such as antimycin A, oligomycin A, and ionomycin. Here, we identify the mycotoxin phomoxanthone A (PXA), derived from the endophytic fungus Phomopsis longicolla, as a mitochondrial toxin. We show that PXA elicits a strong release of Ca2+ from the mitochondria but not from the ER. In addition, PXA depolarises the mitochondria similarly to protonophoric uncouplers such as CCCP, yet unlike these, it does not increase but rather inhibits cellular respiration and electron transport chain activity. The respiration-dependent mitochondrial network structure rapidly collapses into fragments upon PXA treatment. Surprisingly, this fragmentation is independent from the canonical mitochondrial fission and fusion mediators DRP1 and OPA1, and exclusively affects the inner mitochondrial membrane, leading to cristae disruption, release of pro-apoptotic proteins, and apoptosis. Taken together, our results suggest that PXA is a mitochondrial toxin with a novel mode of action that might prove a useful tool for the study of mitochondrial ion homoeostasis and membrane dynamics

Magnetic Dipole Sum Rules for Odd-Mass Nuclei

Sum rules for the total- and scissors-mode M1 strength in odd-A nuclei are derived within the single-j interacting boson-fermion model. We discuss the physical content and geometric interpretation of these sum rules and apply them to ^{167}Er and ^{161}Dy. We find consistency with the former measurements but not with the latter.Comment: 13 pages, Revtex, 1 figure, Phys. Rev. Lett. in pres

First observation of scissors mode states in an odd-mass nucleus

Nuclear resonance fluorescence experiments are reported to search for enhanced M1 scissors mode states in the deformed odd-mass nucleus Dy163. A concentration of dipole strengths near 3 MeV excitation energy is found, which fits nicely into the systematics observed for M1 excitations in the neighboring even-even Dy isotopes. The observed strength distribution and the decay branching ratios are discussed in the context of the interacting boson-fermion model.Dirección General de Investigación Científica y Técnica PB89-063