A TSC signaling node at the peroxisome regulates mTORC1 and autophagy in response to ROS

Subcellular localization is emerging as an important mechanism for mTORC1 regulation. We report that the tuberous sclerosis complex (TSC) signaling node, TSC1, TSC2 and Rheb, localizes to peroxisomes, where it regulates mTORC1 in response to reactive oxygen species (ROS). TSC1 and TSC2 were bound by PEX19 and PEX5, respectively, and peroxisome-localized TSC functioned as a Rheb GAP to suppress mTORC1 and induce autophagy. Naturally occurring pathogenic mutations in TSC2 decreased PEX5 binding, abrogated peroxisome localization, Rheb GAP activity, and suppression of mTORC1 by ROS. Cells lacking peroxisomes were deficient in mTORC1 repression by ROS and peroxisome-localization deficient TSC2 mutants caused polarity defects and formation of multiple axons in neurons. These data identify a role for TSC in responding to ROS at the peroxisome, and identify the peroxisome as a signaling organelle involved in regulation of mTORC1

Searching for the nano-Hertz stochastic gravitational wave background with the Chinese Pulsar Timing Array Data Release I

Observing and timing a group of millisecond pulsars (MSPs) with high rotational stability enables the direct detection of gravitational waves (GWs). The GW signals can be identified from the spatial correlations encoded in the times-of-arrival of widely spaced pulsar-pairs. The Chinese Pulsar Timing Array (CPTA) is a collaboration aiming at the direct GW detection with observations carried out using Chinese radio telescopes. This short article serves as a `table of contents' for a forthcoming series of papers related to the CPTA Data Release 1 (CPTA DR1) which uses observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Here, after summarizing the time span and accuracy of CPTA DR1, we report the key results of our statistical inference finding a correlated signal with amplitude \log A_{\rm c}= -14.4 \,^{+1.0}_{-2.8} for spectral index in the range of $\alpha\in [-1.8, 1.5]$ assuming a GW background (GWB) induced quadrupolar correlation. The search for the Hellings-Downs (HD) correlation curve is also presented, where some evidence for the HD correlation has been found that a 4.6-$\sigma$ statistical significance is achieved using the discrete frequency method around the frequency of 14 nHz. We expect that the future International Pulsar Timing Array data analysis and the next CPTA data release will be more sensitive to the nHz GWB, which could verify the current results.Comment: 18 pages, 6 figures, submitted to "Research in astronomy and astrophysics" 22nd March 202

Hominin occupation of the Chinese Loess Plateau since about 2.1 million years ago

Considerable attention has been paid to dating the earliest appearance of hominins outside Africa. The earliest skeletal and artefactual evidence for the genus Homo in Asia currently comes from Dmanisi, Georgia, and is dated to approximately 1.77-1.85 million years ago (Ma)(1). Two incisors that may belong to Homo erectus come from Yuanmou, south China, and are dated to 1.7 Ma(2); the next-oldest evidence is an H. erectus cranium from Lantian (Gongwangling)-which has recently been dated to 1.63 Ma(3) and the earliest hominin fossils from the Sangiran dome in Java, which are dated to about 1.5-1.6 Ma(4). Artefacts from Majuangou III5 and Shangshazui(6) in the Nihewan basin, north China, have also been dated to 1.6-1.7 Ma. Here we report an Early Pleistocene and largely continuous artefact sequence from Shangchen, which is a newly discovered Palaeolithic locality of the southern Chinese Loess Plateau, near Gongwangling in Lantian county. The site contains 17 artefact layers that extend from palaeosol S15-dated to approximately 1.26 Ma-to loess L28, which we date to about 2.12 Ma. This discovery implies that hominins left Africa earlier than indicated by the evidence from Dmanisi

On the Origin of Tibetans and Their Genetic Basis in Adapting High-Altitude Environments

Since their arrival in the Tibetan Plateau during the Neolithic Age, Tibetans have been well-adapted to extreme environmental conditions and possess genetic variation that reflect their living environment and migratory history. To investigate the origin of Tibetans and the genetic basis of adaptation in a rigorous environment, we genotyped 30 Tibetan individuals with more than one million SNP markers. Our findings suggested that Tibetans, together with the Yi people, were descendants of Tibeto-Burmans who diverged from ancient settlers of East Asia. The valleys of the Hengduan Mountain range may be a major migration route. We also identified a set of positively-selected genes that belong to functional classes of the embryonic, female gonad, and blood vessel developments, as well as response to hypoxia. Most of these genes were highly correlated with population-specific and beneficial phenotypes, such as high infant survival rate and the absence of chronic mountain sickness

Diphosphine-induced chiral propeller arrangement of gold nanoclusters for singlet oxygen photogeneration

In this study, 1,2-bis(diphenylphosphino)ethane (dppe) ligands are used to synthesize gold nanoclusters with an icosahedral Au-13 core. The nanoclusters are characterized and formulated as [Au-13(dppe)5Cl(2)]Cl-3 using synchrotron radiation X-ray diffraction, UV/Vis absorption spectroscopy, electrospray ionization mass spectrometry, and density functional theory (DFT) calculations. The bidentate feature of dppe ligands and the positions of coordinating surface gold atoms induce a helical arrangement that forms a propeller-like structure, which reduces the symmetry of the gold nanocluster to C-1. Therefore, dppe ligands perform as a directing agent to create chiral an ansa metallamacrocycle [Au-13(dppe)(5)Cl-2](3+) nanocluster, as confirmed by simulated electronic circular dichroism spectrum. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap of the [Au-13(dppe)(5)Cl-2](3+) cluster is determined as approx. 1.9 eV, and further confirmed by ultraviolet photoemission spectroscopy analysis and DFT simulation. Furthermore, the photoactivity of [Au-13(dppe)(5)Cl-2](3+) is investigated, with the nanocluster shown to possess near-infrared photoluminescence properties, which can be employed for O-1(2) photogeneration. The quantum yield of O-1(2) photogeneration using the [Au-13(dppe)(5)Cl-2](3+) nanocluster is up to 0.71, which is considerably higher than those of anthracene (an organic dye), and Au-25 and Au-38 nanoclusters

Optimal error regions for quantum state estimation

10.1088/1367-2630/15/12/123026New Journal of Physics15

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Air-Stable Direct Bandgap Perovskite Semiconductors: All-Inorganic Tin-Based Heteroleptic Halides A_<i>x</i>SnCl_<i>y</i>I_<i>z</i> (A = Cs, Rb)

Semiconducting halide perovskites are a class of materials with exciting photoelectronic properties. Compared to the widely studied hybrid organic–inorganic perovskites, the all-inorganic derivatives are less well understood even as they promise high inherent stability. Currently, such materials are limited due to the fact that there is a very narrow choice of inorganic cations that can stabilize the desirable perovskite structure. Herein we report on the synthesis and characterization of novel all-inorganic tin-based perovskites and perovskitoids that can be stabilized by the heteroleptic coordination of chloride and iodide anions, Cs₂SnCl₂I₂ (<b>1</b>) and Cs_2.38Rb_1.62Sn₃Cl₈I₂ (<b>2</b>), consist of two-dimensional (2D) layers of [SnCl₄I₂]^4– octahedra with different connectivity modes. Compound <b>1</b> is an <i>n</i> = 1 Ruddlesden–Popper type perovskite adopting the tetragonal archetype structure (<i>I</i>4/<i>mmm</i> space group; a = 5.5905(3) Å, c = 18.8982(13) Å), while compound <b>2</b> crystallizes as an orthorhombic modification (<i>Cmcm</i> space group; a = 5.6730(11) Å, b = 25.973(5) Å, c = 16.587(3) Å) with corrugated layers. The crystal chemistry changes drastically when Cs⁺ is replaced by the smaller Rb⁺ cation which leads to the isolation of the low dimensional compounds Rb₃SnCl₃I₂ (<b>3a</b>), Rb₃SnCl_2.33I_2.67 (<b>3b</b>) and Rb₇Sn_4.25Cl₁₂I_3.5 (<b>4</b>), thus illustrating the importance of the A-cation size in the formation of perovskites. The 2D perovskites show wide band gaps and relatively large resistivities, associated with their chemical stability against the oxidation of Sn²⁺. The chemical stability is coupled with remarkable electronic properties that derive from the perovskite structure. DFT calculations suggest that both compounds are direct band gap semiconductors with large bandwidths, consistently with the experimentally determined band gaps of <i>E</i>_g = 2.62 and 2.81 eV for <b>1</b> and <b>2</b>, respectively. The combination of stability and favorable electronic structure in heteroleptic-halide perovskites presents a new direction toward the realization of functional devices made exclusively from inorganic perovskites