As a saturable absorption material, the heterostructure with the van der Waals structure has been paid much attention in material science. In general, the heterogeneous combination is able to ...neutralize, or even exceed, the individual material's advantages in some aspects. In this paper, which describes the magnetron sputtering deposition method, the tapered fiber is coated by the MoS2-WS2 heterostructure, and the MoS2-WS2 heterostructure saturable absorber (SA) is fabricated. The modulation depth of the prepared MoS2-WS2 heterostructure SA is measured to be 19.12%. Besides, the theoretical calculations for the band gap and carrier mobility of the MoS2-WS2 heterostructure are provided. By employing the prepared SA, a stable and passively erbium-doped fiber laser is implemented. The generated pulse duration of 154 fs is certified to be the shortest among all fiber lasers based on transition mental dichalcogenides. Results in this paper provide the new direction for the fabrication of ultrafast photon modulation devices.
Time crystals, a phase showing spontaneous breaking of time-translation symmetry, has been an intriguing subject for systems far away from equilibrium. Recent experiments found such a phase in both ...the presence and the absence of localization, while in theories localization by disorder is usually assumed a priori. In this work, we point out that time crystals can generally exist in systems without disorder. A series of clean quasi-one-dimensional models under Floquet driving are proposed to demonstrate this unexpected result in principle. Robust time crystalline orders are found in the strongly interacting regime along with the emergent integrals of motion in the dynamical system, which can be characterized by level statistics and the out-of-time-ordered correlators. We propose two cold atom experimental schemes to realize the clean Floquet time crystals, one by making use of dipolar gases and another by synthetic dimensions.
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Photorespiration is required in C
plants to metabolize toxic glycolate formed when ribulose-1,5-bisphosphate carboxylase-oxygenase oxygenates rather than carboxylates ribulose-1,5-bisphosphate. ...Depending on growing temperatures, photorespiration can reduce yields by 20 to 50% in C
crops. Inspired by earlier work, we installed into tobacco chloroplasts synthetic glycolate metabolic pathways that are thought to be more efficient than the native pathway. Flux through the synthetic pathways was maximized by inhibiting glycolate export from the chloroplast. The synthetic pathways tested improved photosynthetic quantum yield by 20%. Numerous homozygous transgenic lines increased biomass productivity by >40% in replicated field trials. These results show that engineering alternative glycolate metabolic pathways into crop chloroplasts while inhibiting glycolate export into the native pathway can drive increases in C
crop yield under agricultural field conditions.
NLRP6, a member of the nucleotide-binding domain, leucine-rich repeat-containing (NLR) innate immune receptor family, has been reported to participate in inflammasome formation. Activation of ...inflammasome triggers a caspase-1–dependent programming cell death called pyroptosis. However, whether NLRP6 induces pyroptosis has not been investigated. In this study, we showed that NLRP6 overexpression activated caspase-1 and gasdermin-D and then induced pyroptosis of human gingival fibroblasts, resulting in release of proinflammatory mediators interleukin (IL)–1β and IL-18. Moreover, NLRP6 was highly expressed in gingival tissue of periodontitis compared with healthy controls. Porphyromonas gingivalis, which is a commensal bacterium and has periodontopathic potential, induced pyroptosis of gingival fibroblasts by activation of NLRP6. Together, we, for the first time, identified that NLRP6 could induce pyroptosis of gingival fibroblasts by activation of caspase-1 and may play a role in periodontitis.
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The prevalence of diabetes in China is among the highest in the world. For this reason, findings from the 2016 Global Burden of Disease (GBD) study were used to calculate the burden of hyperglycaemia ...and diabetes in China.
Following the general analytical strategy used in GBD 2016, diabetes prevalence and mortality were analyzed by age and gender. Trends in disability-adjusted life years (DALYs) due to diabetes were assessed in 33 province-level administrative units from 1990 to 2016, and similar data were provided for chronic kidney disease (CKD) related to diabetes and, as an overall summarizing measure, for hyperglycaemia expressed as high fasting plasma glucose (HFPG).
From 1990 to 2016, all-age prevalence of diabetes rose from 3.7% to 6.6%, and all-age diabetes and diabetes-related CKD mortality rates increased by 63.5% and 33.3%, respectively, with both rates increasing more rapidly in diabetes patients aged 15–49 years than in any other age groups. In 2016, HFPG became China's sixth leading cause of DALYs, and the attributable DALYs burden was 1802.3/100,000 population. Although the number of diabetes DALYs increased by 95% from 1990 to 2016, age-standardized diabetes DALYs rates increased by only 2.3%. Also, from 1990 to 2016, rates of age-standardized DALYs due to diabetes decreased in 14 provinces, but increased in 19 provinces. High BMI Scores and diets low in whole grains, nuts and seeds were the most important risk factors for diabetes in 2016.
Diabetes and hyperglycaemia constitute a huge health burden in China. The substantial increase in diabetes-related burden represents an ongoing challenge, given the rapidly ageing Chinese population. Thus, a targeted control and preventative strategy needs to be developed at risk factor level to reduce this burden.
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The potential importance of the angular momentum which is gained by accreting white dwarfs (WDs) has been increasingly recognized in the context of Type Ia supernova (SN Ia) single-degenerate model. ...The expectation that the spin of the WD can delay the explosion should help the single-degenerate model to be consistent with the observed properties of most SNe Ia, in particular by avoiding hydrogen contamination. In this paper, we attempt to study the most prominent single-degenerate supersoft (WD + MS) channel when the rotation of accreting WDs is considered. We present a detailed binary population synthesis study to examine the predicted population of SNe Ia for this channel. For our standard model, we find that 77 per cent of these SNe Ia explode with WD masses which are low enough to be supported by solid-body rotation ( ≤ 1.5 M⊙); this is a substantially higher proportion than found by previous work. Only 2 per cent have WD explosion masses ≥2.0 M⊙; these require the initial WD mass to be larger than 1.0 M⊙. We further discuss the possible origin of the diversity of SNe Ia from the pre- and post-accretion properties of the WDs in this population. We also suggest that some SN Ia progenitors with substantial circumstellar hydrogen, including some apparent Type IIn SNe, might be related to WDs which required support from differential rotation to avoid explosion, since these can still be accreting from hydrogen-rich donors with a relatively high mass-transfer rate at the time of the SN explosion.
The performance of four sections of a full-scale embankment constructed on soft soil is examined using a fully coupled and fully three-dimensional finite element analysis. The four sections had ...similar embankment loadings but different improvement options (one unimproved, one with pile-support only, one with a single layer geotextile-reinforced platform and pile-support, and one with two layers of geogrid-reinforced platform and pile-support). Like the field data, the numerical results show that the inclusion of piles decreases the settlement at the subsoil surface to 52% of that for the unimproved section, and the addition of a single layer of geotextile reinforcement (J = 800 kN/m) further reduced settlement to only 31% of that of the unimproved section. The effects of geosynthetic reinforcement and multiple layers of reinforcement on the performance of the pile-supported embankment are discussed. The relative load transfer is calculated using eight existing methods and they are compared with the field measurements and numerical results.
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An 8‐week feeding trial was conducted to evaluate the effects of fish meal (FM) replacement by rice protein concentrate (RPC) with supplementation of microcapsule lysine (ML) or crystalline lysine ...(CL) on growth performance, muscle development and flesh quality of blunt snout bream. Four isonitrogenous and isoenergetic diets were formulated, including FM diet (containing 50 g/kg FM), RPC diet (FM replaced by RPC), MRPC diet (FM replaced by RPC with ML supplementation) and CRPC diet (FM replaced by RPC with CL supplementation). Fish fed FM diet had significantly higher weight gain, feed efficiency, protein efficiency ratio and nitrogen and energy utilization than that of RPC group, but showed no statistical difference with other treatments. In addition, fish fed RPC diet showed higher muscle fibre frequency in the 20‐ to 50‐μm class but lower >50‐μm class and higher cooking loss than that of the other groups. Furthermore, no significant difference was found in whole‐body proximate compositions, frequency distribution of <20‐μm‐diameter fibres, texture, muscle content, collagen, pH 24 hr post‐mortem and sensory quality. The results showed that RPC supplemented with ML or CL could replace fishmeal without any adverse effects on growth performance and flesh quality for blunt snout bream.
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By using the 'standard pair' technique of pairing stars of almost nil and high extinction but otherwise with almost identical stellar parameters from the Sloan Digital Sky Survey (SDSS), and ...combining this information with photometry from the SDSS, Galaxy Evolution Explorer (GALEX), Two Micron All Sky Survey (2MASS) and Wide-field Infrared Survey Explorer (WISE) photometry ranging from the far ultraviolet (UV) to the mid-infrared (mid-IR), we measure dust reddening in the FUV − NUV, NUV − u, u − g, g − r, r − i, i − z, z − J, J − H, H − Ks, Ks − W1 and W1 − W2 colours for thousands of Galactic stars. The measurements, together with the E(B − V) values given by Schlegel et al., allow us to derive the observed, model-free reddening coefficients for these colours. The results are compared with previous measurements and with the predictions of various Galactic reddening laws. We find that (i) the dust reddening map of Schlegel et al. overestimates E(B − V) by about 14 per cent, consistent with the recent work of Schlafly et al. and Schlafly & Finkbeiner; (ii) after accounting for the differences in reddening normalization, the newly deduced reddening coefficients for colours FUV − NUV, NUV − u, u − g, g − r, r − i, i − z, z − J, J − H and H − Ks differ by respectively −1640, 15.5, 12.6, −0.8, 3.4, −0.7, 3.5, 2.5 and 1.4 per cent from the predictions of the Fitzpatrick reddening law for an assumed total-to-selective extinction ratio R(V) = 3.1, and by respectively −1730, 13.0 , 8.1, 10.0, 8.0, −13.5, −1.7, −6.7 and −17.1 per cent from the predictions of the CCM reddening law; and (iii) all the new reddening coefficients, except those for NUV − u and u − g, favour the R(V) = 3.1 Fitzpatrick reddening law over the R(V) = 3.1 CCM and O'Donnell reddening laws. Using the Ks-band extinction coefficient predicted by the R(V) = 3.1 Fitzpatrick law and the observed reddening coefficients, we deduce new extinction coefficients for the FUV, NUV, u, g, r, i, z, J, H, W1 and W2 passbands. We recommend that the new reddening and extinction coefficients should be used in the future and that the Fitzpatrick reddening law in the UV should probably be updated. We stress, however, that the FUV- and NUV-band coefficients should be used with caution, given their relatively large measurement uncertainties. Finally, potential applications of the 'standard pair' technique with the upcoming LAMOST Galactic surveys are discussed.
Metal hydride clusters have historically been studied to unravel their aesthetically pleasing molecular structures and interesting properties, especially toward hydrogen related applications. Central ...to this work is the hydride ligand, H¯, the smallest closed-shell spherical anion known. Two new developments in polyhydrido nanocluster chemistry include the determination of heretofore unknown hydride coordination modes and novel structural constructs, and conversion from the molecular entities to rhombus-shaped copper nanoparticles (CuNPs). These advances, together with hydrogen evolution and catalysis, have provided both experimentalists and theorists with a rich scientific directive to further explore. The isolation of hexameric {(Ph3P)CuH}6 (Stryker reagent) could be regarded as the springboard for the recent emergence of polyhydrido copper cluster chemistry due to its utilization in a variety of organic chemical transformations. The stability of clusters of various nuclearity was improved through phosphine, pyridine, and carbene type ligands. Our focus lies with the isolation of novel copper (poly)hydride clusters using mostly the phosphor-1,1-dithiolato type ligands. We found such chalcogen-stabilized clusters to be exceptionally air and moisture stable over a wide range of nuclearities (Cu7 to Cu32). In this Account, we (i) report on state-of-the-art copper hydride cluster chemistry, especially with regards to the diverse and novel structural types generally, and newly discovered hydride coordination modes in particular, (ii) demonstrate the indispensable power of neutron diffraction for the unambiguous assignment and location of hydride ligand(s) within a cluster, and (iii) prove unique transformations that can occur not only between well characterized high nuclearity clusters, but also how such clusters can transform to uniquely shaped nanoparticles of several nanometers in diameter through copper hydride reduction. The increase in the number of low- to high-nuclearity hydride clusters allows for different means by which they can be classified. We chose a classification based on the coordination mode of hydride ligand within the cluster. This includes copper clusters associated with bridging (μ2-H) and capping (μ3-H) hydride modes, followed by an interstitial (μ4-H) hydride mode that was introduced for the first time into octa- and hepta-nuclear copper clusters stabilized by dichalcogen-type ligands. This breakthrough provided a means to explore higher nuclearity polyhydrido nanoclusters, which contain both capping (μ3-H) and interstitial (μ(4–6)-H) hydrides. The presence of bidentate ligands having mixed S/P dative sites led to air- and moisture-stable copper hydride nanoclusters. The formation of rhombus-shaped nanoparticles (CuNPs) from copper polyhydrides in the presence of excess borohydrides suggests the presence of metal hydrides as intermediates during the formation of nanoparticles.
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