Mössbauer and electron microscopy study of martensitic transformations in an Fe-Mn-Mo alloy

The kinetic, morphological, crystallographic, and magnetic characteristics of thermally induced martensites in Fe-13.4wt% Mn-5.2wt% Mo alloy were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Mössbauer spectroscopy. The experimental results reveal that two types of thermal-induced martensites, ? (hcp) and α′ (bcc) martensites, are formed in the as-quenched condition, and these transformations have athermal characters. Mo addition to the Fe-Mn alloy does not change the coexistence of ? and α′ martensites with the Mn content between 10wt% and 15wt%. Besides, Mössbauer spectra reveal a paramagnetic character with a singlet for the γ (fcc) austenite and ? martensite phases and a ferromagnetic character with a broad sextet for the α′ martensite phase. The volume fraction of α′ martensite forming in the quenched alloy is much more than that of the ? martensite.     

Cellular localization of androgen in the brain and pituitary after the injection of tritiated testosterone

Zusammenfassung Nach Injektion von³H-Testosteron wurde mit Hilfe der Trocken-Autoradiographie eine selektive Aufnahme und Speicherung von Radioaktivität in Kernen spezifischer Neurone im Hypothalamus, in der präoptisch-parolfaktorischen Region, im Septum, im Hippokampus und in der Amygdala beobachtet. Im Hypophysenvorderlappen war Radioaktivität in den Zellkernen von Basophilen nachweisbar. Die autoradiographischen Ergebnisse unterstützen das Konzept eines doppelten Androgen-Feedbacks auf der Ebene des Zentralnervensystems und der Hypophyse.

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We thank Mrs.Gerda Michalsky and Mrs.Anu Turnbull for their technical assistance. This study was supported by PHS grant No. AM1 929 to W.E.S. and a grant from the Rockefeller Foundation to the Laboratories for Reproductive Biology, Chapel Hill, North Carolina.     

Decoherence-protected quantum gates for a hybrid solid-state spin register

Protecting the dynamics of coupled quantum systems from decoherence by the environment is a key challenge for solid-state quantum information processing. An idle quantum bit (qubit) can be efficiently insulated from the outside world by dynamical decoupling, as has recently been demonstrated for individual solid-state qubits. However, protecting qubit coherence during a multi-qubit gate is a non-trivial problem: in general, the decoupling disrupts the interqubit dynamics and hence conflicts with gate operation. This problem is particularly salient for hybrid systems, in which different types of qubit evolve and decohere at very different rates. Here we present the integration of dynamical decoupling into quantum gates for a standard hybrid system, the electron-nuclear spin register. Our design harnesses the internal resonance in the coupled-spin system to resolve the conflict between gate operation and decoupling. We experimentally demonstrate these gates using a two-qubit register in diamond operating at room temperature. Quantum tomography reveals that the qubits involved in the gate operation are protected as accurately as idle qubits. We also perform Grover's quantum search algorithm, and achieve fidelities of more than 90% even though the algorithm run-time exceeds the electron spin dephasing time by two orders of magnitude. Our results directly allow decoherence-protected interface gates between different types of solid-state qubit. Ultimately, quantum gates with integrated decoupling may reach the accuracy threshold for fault-tolerant quantum information processing with solid-state devices.     

Cellular and subcellular localization of3H-estradiol or its metabolites in the pituitary of the neonatal female rat

Zusammenfassung Bei 2 Tage alten Ratten wurde markiertes Oestradiol-17 injiziert. Im Hypophysenvorderlappen waren weniger als 10% der Zellkerne markiert. Diese Zellen befanden sich vorwiegend in der Peripherie. Im Zwischen- und Hinterlappen fanden sich keine markierten Zellen. Eine Vorbehandlung mit nicht markiertem Oestradiol hemmte die nukleare Aufnahme der Radioaktivität, was beweist, dass diese mit Oestradiol oder dessen Metaboliten verbunden sein muss.     

Use of ionic liquid in leaching process of brass wastes for copper and zinc recovery

Brass ash from the industrial brass manufacturer in Turkey was leached using the solutions of ionic liquid (IL) 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO₄) at ambient pressure in the presence of hydrogen peroxide (H₂O₂) and potassium peroxymonosulfate (oxone) as the oxidants. Parameters affecting leaching efficiency, such as dissolution time, IL concentration, and oxidizing agent addition, were investigated. The results show that [bmim]HSO₄ is an efficient IL for the brass ash leaching, providing the dissolution efficiencies of 99% for Zn and 24.82% for Cu at a concentration of 50vol% [bmim]HSO₄ in the aqueous solution without any oxidant. However, more than 99% of zinc and 82% of copper are leached by the addition of 50vol% H₂O₂ to the [bmim]HSO₄ solution. Nevertheless, the oxone does not show the promising oxidant behavior in leaching using [bmim]HSO₄.     

Utilization of waste polyethylene terephthalate as a reducing agent in the reduction of iron ore composite pellets

The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate (PET), because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450°C for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron (iron nuggets) were reduction at 1450°C for 10 min using composite pellets containing 60% PET and 40% coke.     

Nuclear isomers in superheavy elements as stepping stones towards the island of stability

A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the 'island of stability'; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons--the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.