Recent studies consistently support a hypoxia response in the adipose tissue in obese animals. The observations have led to the formation of an exciting concept, adipose tissue hypoxia (ATH), in the ...understanding of major disorders associated with obesity. ATH may provide cellular mechanisms for chronic inflammation, macrophage infiltration, adiponectin reduction, leptin elevation, adipocyte death, endoplasmic reticulum stress and mitochondrial dysfunction in white adipose tissue in obesity. The concept suggests that inhibition of adipogenesis and triglyceride synthesis by hypoxia may be a new mechanism for elevated free fatty acids in the circulation in obesity. ATH may represent a unified cellular mechanism for a variety of metabolic disorders and insulin resistance in patients with metabolic syndrome. It suggests a new mechanism of pathogenesis of insulin resistance and inflammation in obstructive sleep apnea. In addition, it may help us to understand the beneficial effects of caloric restriction, physical exercise and angiotensin II inhibitors in the improvement of insulin sensitivity. In this review article, literatures are reviewed to summarize the evidence and possible cellular mechanisms of ATH. The directions and road blocks in the future studies are analyzed.
Strontium optical lattice clocks have the potential to simultaneously interrogate millions of atoms with a high spectroscopic quality factor of 4 × 1017. Previously, atomic interactions have forced a ...compromise between clock stability, which benefits from a large number of atoms, and accuracy, which suffers from density-dependent frequency shifts. Here we demonstrate a scalable solution that takes advantage of the high, correlated density of a degenerate Fermi gas in a three-dimensional (3D) optical lattice to guard against on-site interaction shifts. We show that contact interactions are resolved so that their contribution to clock shifts is orders of magnitude lower than in previous experiments. A synchronous clock comparison between two regions of the 3D lattice yields a measurement precision of 5 × 10−19 in 1 hour of averaging time.
Superconducting Dome in a Gate-Tuned Band Insulator Ye, J. T.; Zhang, Y. J.; Akashi, R. ...
Science (American Association for the Advancement of Science),
11/2012, Letnik:
338, Številka:
6111
Journal Article
Recenzirano
A dome-shaped superconducting region appears in the phase diagrams of many unconventional superconductors. In doped band insulators, however, reaching optimal superconductivity by the fine-tuning of ...carriers has seldom been seen. We report the observation of a superconducting dome in the temperature—carrier density phase diagram of MoS₂, an archetypal band insulator. By quasi-continuous electrostatic carrier doping achieved through a combination of liquid and solid gating, we revealed a large enhancement in the transition temperature T c occurring at optimal doping in the chemically inaccessible low-carrier density regime. This observation indicates that the superconducting dome may anse even in doped band insulators.
Tungsten diselenide (WSe2) and related transition metal dichalcogenides exhibit interesting optoelectronic properties owing to their peculiar band structures originating from the valley degree of ...freedom. Although the optical generation and detection of valley polarization has been demonstrated, it has been difficult to realize active valley-dependent functions suitable for device applications. We report an electrically switchable, circularly polarized light source based on the material's valley degree of freedom. Our WSe2-based ambipolar transistors emit circularly polarized electroluminescence from p-i-n junctions electrostatically formed in transistor channels. This phenomenon can be explained qualitatively by the electron-hole overlap controlled by the in-plane electric field. Our device demonstrates a route to exploit the valley degree of freedom and the possibility to develop a valley-optoelectronics technology.
In Cooper pairs--pairs of electrons responsible for the exotic properties of superconductors--the two electrons' spins typically point in opposite directions. A strong-enough external magnetic field ...will destroy superconductivity by making the spins point in the same direction. Lu et al. observed a two-dimensional superconducting state in the material MoS2 that was surprisingly immune to a magnetic field applied in the plane of the sample (see the Perspective by Suderow). The band structure of MoS2 and its spin-orbit coupling conspired to create an effective magnetic field that reinforced the electron pairing, with spins aligned perpendicular to the sample. Science, this issue p. 1353; see also p. 1316 The Zeeman effect, which is usually detrimental to superconductivity, can be strongly protective when an effective Zeeman field from intrinsic spin-orbit coupling locks the spins of Cooper pairs in a direction orthogonal to an external magnetic field. We performed magnetotransport experiments with ionic-gated molybdenum disulfide transistors, in which gating prepared individual superconducting states with different carrier dopings, and measured an in-plane critical field Bc2 far beyond the Pauli paramagnetic limit, consistent with Zeeman-protected superconductivity. The gating-enhanced Bc2 is more than an order of magnitude larger than it is in the bulk superconducting phases, where the effective Zeeman field is weakened by interlayer coupling. Our study provides experimental evidence of an Ising superconductor, in which spins of the pairing electrons are strongly pinned by an effective Zeeman field.
It has been reported that irisin regulated exercise-mediated adipocyte browning; however, the systematical effects of irisin on the metabolism of glucose and lipid in diabetes are largely unknown. In ...the present study, we investigated the role and underlying mechanism of irisin in glucose utilization and lipid metabolism in diabetic mice.
A mouse model of diabetes was established by feeding C57BL/6 mice with high-fat diet. The diabetic mice were then treated with irisin. To mimic type 2 diabetes in vitro, myocytes and hepatocytes were cultured in a medium of high glucose and high fat. Glucose uptake, fatty acid oxidation and the expression of related protein were evaluated.
Irisin improved glucose tolerance and glucose uptake as evidenced by increased (18)F-FDG accumulation and GLUT4 translocation in diabetic skeletal muscle. Irisin also increased glucose uptake in myocytes cultured in high glucose/high fatty acid medium. In contrast, irisin reduced the expression of PEPCK and G6Pase, which are involved in gluconeogenesis, in diabetic liver. Consistently, irisin reduced fat weight and serum total cholesterol and triglyceride levels in diabetic mice, but increased acetyl coenzyme A carboxylase-β phosphorylation in muscle tissue and uncoupling protein 1 expression in fat tissue. In addition, irisin increased the oxidation of fatty acid in myocytes. Knockdown of the adenosine monophosphate (AMP)-activated protein kinase (AMPK) attenuated the effects of irisin on glucose uptake and fatty acid β-oxidation in myocytes. Similarly, inhibition of AMPK by a specific inhibitor reduced the effects of irisin on PEPCK and G6Pase expression in hepatocytes.
Our results suggest that irisin has an essential role in glucose utilization and lipid metabolism, and irisin is a promising pharmacological target for the treatment of diabetes and its complications.
Scaffolds that couple electrical and elastic properties may be valuable for cardiac cell function. However, existing conductive materials do not mimic physiological properties. We prepared and ...characterized a tunable, hybrid hydrogel scaffold based on Au nanoparticles homogeneously synthesized throughout a polymer templated gel. Conductive gels had Young’s moduli more similar to myocardium relative to polyaniline and polypyrrole, by 1–4 orders of magnitude. Neonatal rat cardiomyocytes exhibited increased expression of connexin 43 on hybrid scaffolds relative to HEMA with or without electrical stimulation.
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