We report on the development of a high‐resolution and highly efficient beamline for soft X‐ray resonant inelastic X‐ray scattering (RIXS) located at the Taiwan Photon Source. This beamline adopts an ...optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher‐order aberrations, as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum‐resolved RIXS measurements with scattering angles over a wide range. Several high‐precision instruments developed in‐house for this beamline are described briefly. The best energy resolution obtained from this AGM–AGS beamline was 12.4 meV at 530 eV, achieving a resolving power of 4.2 × 104, while the bandwidth of the incident soft X‐rays was kept at 0.5 eV. To demonstrate the scientific impact of high‐resolution RIXS, we present an example of momentum‐resolved RIXS measurements on a high‐temperature superconducting cuprate, i.e. La2–xSrxCuO4. The measurements reveal the A1g buckling phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge‐density waves.
The development of a high‐resolution and highly efficient beamline for soft X‐ray resonant inelastic X‐ray scattering (RIXS) located at the Taiwan Photon Source is reported.
Aims/hypothesis
Many of the effects of resveratrol are consistent with the activation of AMP-activated protein kinase (AMPK), silent information regulator T1 (SIRT1) and peroxisome ...proliferator-activated receptor (PPAR)γ co-activator 1α (PGC-1α), which play key roles in the regulation of lipid and glucose homeostasis, and in the control of oxidative stress. We investigated whether resveratrol has protective effects on the kidney in type 2 diabetes.
Methods
Four groups of male C57BLKS/J
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mice were used in this study. Resveratrol was administered via gavage to diabetic and non-diabetic mice, starting at 8 weeks of age, for 12 weeks.
Results
The
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mice treated with resveratrol had decreased albuminuria. Resveratrol ameliorated glomerular matrix expansion and inflammation. Resveratrol also lowered the NEFA and triacylglycerol content of the kidney, and this action was related to increases in the phosphorylation of AMPK and the activation of SIRT1–PGC-1α signalling and of the key downstream effectors, the PPARα–oestrogen-related receptor (ERR)-1α–sterol regulatory element-binding protein 1 (SREBP1). Furthermore, resveratrol decreased the activity of phosphatidylinositol-3 kinase (PI3K)–Akt phosphorylation and class O forkhead box (FOXO)3a phosphorylation, which resulted in a decrease in B cell leukaemia/lymphoma 2 (BCL-2)-associated X protein (BAX) and increases in BCL-2, superoxide dismutase (SOD)1 and SOD2 production. Consequently, resveratrol reversed the increase in renal apoptotic cells and oxidative stress, as reflected by renal 8-hydroxy-deoxyguanosine (8-OH-dG), urinary 8-OH-dG and isoprostane concentrations. Resveratrol prevented high-glucose-induced oxidative stress and apoptosis in cultured mesangial cells through the phosphorylation of AMPK and activation of SIRT1–PGC-1α signalling and the downstream effectors, PPARα–ERR-1α–SREBP1.
Conclusions/interpretation
The results suggest that resveratrol prevents diabetic nephropathy in
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mice by the phosphorylation of AMPK and activation of SIRT1–PGC-1α signalling, which appear to prevent lipotoxicity-related apoptosis and oxidative stress in the kidney.
Mammalian sirtuin 1 (SIRT1) has connected to an ever widening circle of activities that encompass cellular stress resistance, energy metabolism and tumorigenesis. However, underlying mechanisms ...leading to oncogenic SIRT1 overexpression are less understood. In this study, we identified SIRT1 regulatory microRNA (miRNA) and its function in hepatocellular carcinoma (HCC). Aberrant SIRT1 overexpression was demonstrated in a subset of human HCCs. SIRT1 knockdown suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins. This led to hypophosphorylation of pRb, which inactivated E2F/DP1 target gene transcription, and thereby caused significant increase of HCC cells to remain in the G1/S phase. A comprehensive miRNA profiling analysis indentified five putative endogenous miRNAs that are significantly downregulated in HCC. Ectopic expression of miRNA mimics evidenced miR-29c to suppress SIRT1 in HCC cells. Notably, ectopic miR-29c expression repressed cancer cell growth and proliferation, and it recapitulated SIRT1 knockdown effects in HCC cells. In addition, miR-29c expression was downregulated in a large cohort of HCC patients, and low expression of miR-29c was significantly associated with poor prognosis of HCC patients. Taken together, we demonstrated that miR-29c suppresses oncogenic SIRT1 by way of binding to 3'-untranslated region of SIRT1 mRNA causing translational inhibition in liver cancer cells. The loss or suppression of miR-29c may cause aberrant SIRT1 overexpression and promotes liver tumorigenesis. Overall, we suggest that miR-29c functions as a tumor suppressor by regulating abnormal SIRT1 activity in liver.
A central goal within quantum optics is to realize efficient, controlled interactions between photons and atomic media. A fundamental limit in nearly all applications based on such systems arises ...from spontaneous emission, in which photons are absorbed by atoms and then rescattered into undesired channels. In typical theoretical treatments of atomic ensembles, it is assumed that this rescattering occurs independently, and at a rate given by a single isolated atom, which in turn gives rise to standard limits of fidelity in applications such as quantum memories for light or photonic quantum gates. However, this assumption can in fact be dramatically violated. In particular, it has long been known that spontaneous emission of a collective atomic excitation can be significantly suppressed through strong interference in emission between atoms. While this concept of “subradiance” is not new, thus far the techniques to exploit the effect have not been well understood. In this work, we provide a comprehensive treatment of this problem. First, we show that in ordered atomic arrays in free space, subradiant states acquire an elegant interpretation in terms of optical modes that are guided by the array, which only emit due to scattering from the ends of the finite system. We also go beyond the typically studied regime of a single atomic excitation and elucidate the properties of subradiant states in the many-excitation limit. Finally, we introduce the new concept of “selective radiance.” Whereas subradiant states experience a reduced coupling to all optical modes, selectively radiant states are tailored to simultaneously radiate efficiently into a desired channel while scattering into undesired channels is suppressed, thus enabling an enhanced atom-light interface. We show that these states naturally appear in chains of atoms coupled to nanophotonic structures, and we analyze the performance of photon storage exploiting such states. We find numerically that selectively radiant states allow for a photon storage error that scales exponentially better with the number of atoms than previously known bounds.
Quantum simulation with cold atoms in optical lattices is an attractive avenue for explorations of quantum many-body physics. A principal challenge in the field is to increase the energy and length ...scales in current set-ups, thereby reducing temperature and coherence-time requirements. Here, we present a new paradigm for high-density, two-dimensional optical lattices in photonic crystal waveguides. Specially engineered two-dimensional photonic crystals provide a practical platform to trap atoms and engineer their interactions in ways that surpass the limitations of current technologies and enable investigations of novel quantum many-body matter. Our schemes remove the constraint on the lattice constant set by the free-space optical wavelength in favour of deeply sub-wavelength atomic arrays. We further describe possibilities for atom-atom interactions mediated by photons in two-dimensional photonic crystal waveguides with energy scales several orders of magnitude larger than for exchange interactions in free-space lattices and with the capability to engineer strongly long-range interactions.
Kuroshio velocity structure and transport in the East China Sea (ECS) were investigated as part of a 23‐month study using inverted echo sounders and acoustic Doppler current profilers (ADCPs) along ...the regularly sampled PN‐line. Flow toward the northeast is concentrated near the continental shelf with the mean surface velocity maximum located 30 km offshore from the shelf break (taken as the 170 m isobath). There are two regions of southwestward flow: a deep countercurrent over the continental slope beneath the Kuroshio axis and a recirculation offshore which extends throughout the whole water column. There is a bimodal distribution to the depth of maximum velocity with occurrence peaks at the surface and 210 dbar. When the maximum velocity is located within the top 80 m of the water column, it ranges between 0.36 m/s and 2.02 m/s; when the maximum velocity is deeper than 80 m, it ranges between 0.31 m/s and 1.11 m/s. The 13‐month mean net absolute transport of the Kuroshio in the ECS is 18.5 ± 0.8 Sv (standard deviation, σ = 4.0 Sv). The mean positive and negative portions of this net flow are 24.0 ± 0.9 Sv and −5.4 ± 0.3 Sv, respectively.
The integration of nanophotonics and atomic physics has been a long-sought goal that would open new frontiers for optical physics, including novel quantum transport and many-body phenomena with ...photon-mediated atomic interactions. Reaching this goal requires surmounting diverse challenges in nanofabrication and atomic manipulation. Here we report the development of a novel integrated optical circuit with a photonic crystal capable of both localizing and interfacing atoms with guided photons. Optical bands of a photonic crystal waveguide are aligned with selected atomic transitions. From reflection spectra measured with average atom number N=1.1+/-0.4, we infer that atoms are localized within the waveguide by optical dipole forces. The fraction of single-atom radiative decay into the waveguide is Γ1D/Γ'≃(0.32±0.08), where Γ1D is the rate of emission into the guided mode and Γ' is the decay rate into all other channels. Γ1D/Γ' is unprecedented in all current atom-photon interfaces.
The chromium terephthalate MIL‐101 has been prepared rapidly and efficiently by using microwave‐assisted hydrothermal synthesis. The resulting material exhibits giant pores and very large surface ...areas and demonstrates a huge, rapid adsorption of benzene in both vapor (see figure) and liquid phases.
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