Strontium titanate (SrTiO3) is the first and best known superconducting semiconductor. It exhibits an extremely low carrier density threshold for superconductivity, and possesses a phase diagram similar to that of high-temperature superconductors--two factors that suggest an unconventional pairing mechanism. Despite sustained interest for 50 years, direct experimental insight into the nature of electron pairing in SrTiO3 has remained elusive. Here we perform transport experiments with nanowire-based single-electron transistors at the interface between SrTiO3 and a thin layer of lanthanum aluminate, LaAlO3. Electrostatic gating reveals a series of two-electron conductance resonances-paired electron states--that bifurcate above a critical pairing field Bp of about 1-4 tesla, an order of magnitude larger than the superconducting critical magnetic field. For magnetic fields below Bp, these resonances are insensitive to the applied magnetic field; for fields in excess of Bp, the resonances exhibit a linear Zeeman-like energy splitting. Electron pairing is stable at temperatures as high as 900 millikelvin, well above the superconducting transition temperature (about 300 millikelvin). These experiments demonstrate the existence of a robust electronic phase in which electrons pair without forming a superconducting state. Key experimental signatures are captured by a model involving an attractive Hubbard interaction that describes real-space electron pairing as a precursor to superconductivity.
Transient receptor potential (TRP) cation-selective channels are an emerging class of proteins that are involved in a variety of important biological functions including pain transduction, thermosensation, mechanoregulation, and vasorelaxation. Utilizing a bioinformatics approach, we have identified the full-length human TRPM3 (hTRPM3) as a member of the TRP family. Following the identification of the founding member of this family, dTRP, which is from a Drosophila mutant with abnormal visual signal transduction (2), mammalian homologues have been cloned and all of them contain a six-transmembrane domain followed by a TRP motif (XWKFXR). Based on homology, they are divided into three subfamilies: TRPC (canonical), TRPV (vanilloid), and TRPM (melastatin) (3). Members of the TRPM subfamily have unusually long cytoplasmic tails at both ends of the channel domain, and some of the family members have an enzyme domain in the C-terminal region. Despite their similarities of structure, TRPMs have different ion-conductive properties, activation mechanisms, and putative biological functions. TRPM1 is down-regulated in metastatic melanomas (4). TRPM2 is a Ca 2ϩ -permeable channel that contains an ADP-ribose pyrophosphatase domain and can be activated by ADP-ribose, NAD (5, 6), and changes in redox status (7). The TRPM2 gene is mapped to the chromosome region linked to bipolar affective disorder, nonsyndromic hereditary deafness, Knobloch syndrome, and holosencephaly (8). Two splice variants of TRPM4 have been described. TRPM4a is predominantly a Ca 2ϩ -permeable channel (9); whereas TRPM4b conducts monovalent cations upon activation by changes in intracellular Ca 2ϩ (10). TRPM5 is associated with Beckwith-Wiedemann syndrome and a predisposition to neoplasias (11). TRPM7, another bifunctional protein, has kinase activity in addition to its ion channel activity. TRPM7 is regulated by Mg 2ϩ -ATP and/or inositol 1,4,5-disphosphate and is required for cell viability (12-14). TRPM8 is up-regulated in prostate cancer and other malignancies (15). Recently, it has been shown to be a receptor that senses cold stimuli (16,17).Using a bioinformatics approach, we have identified a member of the human TRPM subfamily that we have called hTRPM3, consistent with the unified TRP nomenclature (3). hTRPM3 contains long N and C termini, although it does not contain any additional enzymatic features. hTRPM3 mRNA is expressed primarily in kidney with lower levels in brain, testis, and spinal cord. When expressed in HEK 293 cells, hTRPM3 is co-localized with the plasma membrane and is capable of mediating Ca 2ϩ entry. This hTRPM3-mediated Ca 2ϩ conductance * The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.The nucleotide sequence (s)
The pharmacokinetics of a novel antipsychotic agent, risperidone, and the prolactin response were studied in 12 dextromethorphan-phenotyped healthy men after administration of 1 mg risperidone intravenously, intramuscularly, and orally. The formation of the equipotent major metabolite, 9-hydroxyrisperidone, exhibited CYP2D6-related polymorphism. The plasma area under the concentration-time curve from time zero to infinity ratio of 9-hydroxyrisperidone to risperidone averaged 3 (intravenous and intramuscular) and 6 (oral administration) in the extensive metabolizers and 0.2 in the poor metabolizers. Risperidone half-life was about 3 hours in extensive metabolizers and 22 hours in poor metabolizers. Risperidone absolute oral bioavailability was 66%. The pharmacokinetics of the active moiety (risperidone plus 9-hydroxyrisperidone) varied little among subjects (mean terminal half-life, 20 +/- 2 1/2 hours; absolute oral and intramuscular bioavailability, 100%). The prolactin response correlated best with the plasma active moiety, which showed little hysteresis. It is concluded that risperidone metabolic polymorphism on increased plasma prolactin is minimal and that the active moiety is clinically relevant.
Reports of emergent conductivity, superconductivity and magnetism have helped to fuel intense interest in the rich physics and technological potential of complex-oxide interfaces. Here we employ magnetic force microscopy to search for room-temperature magnetism in the well-studied LaAlO 3 /SrTiO 3 system. Using electrical top gating to control the electron density at the oxide interface, we directly observe the emergence of an in-plane ferromagnetic phase as electrons are depleted from the interface. Itinerant electrons that are reintroduced into the interface align antiferromagnetically with the magnetization at first screening and then destabilizing it as the conductive regime is approached. Repeated cycling of the gate voltage results in new, uncorrelated magnetic patterns. This newfound control over emergent magnetism at the interface between two non-magnetic oxides portends a number of important technological applications.
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