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This paper presents an investigation of the precise point positioning (PPP) performance of a combined solution from BDS-2 and BDS-3 satellites. To simultaneously process different BDS signal observations, i.e., B1/B1C, B2/B2a and B3C, undifferenced and uncombined observations with ionosphere delay constrained by the deterministic plus stochastic ionosphere model are used in the basic model. Special attention is paid to code bias and receiver clock parameters in the derivation of the observation model. The analysis is carried out using more than one-month data for BDS-2 and BDS-3 collected at the CANB, DWIN, KNDY and PETH stations in the Asia-Pacific region. The results suggest that compared with BDS-2 alone, the BDS-2 and BDS-3 solution provides significantly more accurate PPP, with increases of 28%, 21% and 5% in the up, north and east directions, respectively. In addition, the average root mean square error decreases to 0·21, 0·13 and 0·16 m for the three directions. Furthermore, the PPP convergence time for BDS-2 and BDS-3 is about 1·5 h and less than 1 h for the horizontal and vertical components, respectively, whereas that for BDS-2 alone is about 2·3 h for both directions.
Underground Nuclear Astrophysics in China (JUNA) will take the advantage of the ultra-low background in Jinping underground lab. High current accelerator with an ECR source and detectors were commissioned. JUNA plans to study directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. At the first period, JUNA aims at the direct measurements of 25Mg(p,γ)26 Al, 19F(p,α) 16 O, 13C(α, n) 16O and 12C(α,γ) 16O near the Gamow window. The current progress of JUNA will be given.
The influence of heat treatment (homogenization) on the microstructure, mechanical behavior, and soft magnetic properties of a face-centered cubic (fcc)-based high-entropy alloy (HEA), Fe29Co28Ni29Cu7Ti7, fabricated by casting, was investigated in detail. The as-cast Fe29Co28Ni29Cu7Ti7 HEA was composed of a primary fcc phase containing coherent dispersed L12 nanoprecipitates and trace amounts of a needle-like phase. The tensile yield strength (σ0.2), ultimate strength, and total elongation of the as-cast alloy are 917 MPa, 1060 MPa, and 1.8%, respectively. Following homogenization, the alloy having a single fcc phase shows a decrease of ∼ 55% in yield strength and a decrease of ∼ 36% in ultimate strength; however, the total elongation is increased from 1.8 to 52%. Saturation magnetization (Msat) is decreased from 111.54 to 110.34 Am2/kg, by contrast, coercivity (Hc) is increased from 266.65 to 966.89 A/m. The dissolution of precipitates and grain growth are mainly responsible for the changes in magnetic properties and mechanical behavior.
Cycle slip detection for single frequency Global Navigation Satellite System (GNSS) data is currently mainly based on measurement modelling or prediction, which cannot be effectively performed for kinematic applications and it is difficult to detect or repair small cycle slips such as half-cycle slips. In this paper, a new method that is based on the total differential of ambiguity and Least-Squares Adjustment (LSA) for cycle slip detection and repair is introduced and validated. This method utilises only carrier-phase observations to build an ambiguity function. LSA is then conducted for detecting and repairing cycle slips, where the coordinate and cycle slips are obtained successively. The performance of this method is assessed through processing short and long baselines in static and kinematic modes and the impact of linearization and atmospheric errors are analysed at the same time under a controlled variable method. The results indicate this method is very effective and reliable in detecting and repairing multiple cycle slips, especially small cycle slips.
Although many studies worldwide have focused on the relationship between vitamin D and insulin resistance, results remain controversial. Furthermore, concentrations of serum 25-hydroxyvitamin D (25(OH)D) in the Chinese population are unclear. We aimed to investigate vitamin D status and its correlation with insulin resistance among a Chinese adult population.
Serum 25(OH)D, fasting blood glucose, fasting insulin, glycated Hb (HbA1c) and other metabolic parameters were assessed. Neck circumference, waist circumference, hip circumference, weight and height were also measured. Lifestyle factors including smoking and drinking status were obtained. Diabetes mellitus was diagnosed by HbA1c according to the 2010 American Diabetes Association criteria.
Of 7200 residents included, 6597 individuals were ultimately analysed.
We enrolled 2813 males (mean age 52·7 (sd 13·5) years) and 3784 females (52·3 (sd 13·5) years); mean serum 25(OH)D concentration was 43·1 (sd 11·6) and 39·6 (sd 9·8) nmol/l, respectively. Additionally, 83·3 % of participants were 25(OH)D deficient. A significant difference in 25(OH)D was observed between males and females in winter and spring (P<0·001). Furthermore, 25(OH)D concentrations were inversely associated with the homeostasis model assessment of insulin resistance (HOMA-IR) in the overweight and pre-diabetic populations. After adjusting for several variables, 25(OH)D was significantly associated with HOMA-IR in winter. When 25(OH)D values were categorized into quartiles, HOMA-IR was significantly associated with decreasing 25(OH)D.
The majority of the Chinese population was vitamin D deficient and this deficiency was negatively associated with insulin resistance, particularly in the overweight and pre-diabetic populations. Moreover, these associations might be more evident in the winter.
Our previous studies have shown that vitamin A (VA) status is associated with antiviral immunity and pathogenic conditions in enterovirus 71 (EV71)-infected children. In the present study, we established an in vitro model to investigate the effects and potential mechanism of the antiviral activity of VA. Human monocytic U937 cells were cultured in vitro and infected with EV71. All-trans-retinoic acid (ATRA), the active metabolite of VA, and Ro 41-5253, a retinoic acid receptor-α (RAR-α) antagonist, were used as the experimental treatment agents. The percentage of EV71-infected cells and apoptosis induced by EV71 were determined using flow cytometry. The level of interferon-α (IFN-α) in the supernatants of the cultures was detected using ELISA. The expression of retinoid-induced gene I (RIG-I) and its downstream genes was examined with real-time quantitative PCR. The results indicated that ATRA reduced the percentage of EV71-infected cells and protected cells against EV71-induced apoptosis. Correspondingly, ATRA increased the production of IFN-α one of the most important antiviral cytokines, at both mRNA and protein levels in EV71-infected cells. In addition, the expression of RIG-I mRNA and its downstream genes was up-regulated by ATRA in EV71-infected cells. Ro 41-5253 abrogated the inhibitory effects of ATRA on EV71. The present findings suggest that ATRA is an interferon-inducing agent with antiviral activity against EV71 in vitro and that its actions are mediated at least in part by RAR-α activity and the RIG-I signalling pathway.
Dielectric capacitors for energy storage are of great importance in modern electronics and electric systems. It is a challenge to realize the high energy density while maintain the low dielectric loss. We investigated an ultra high breakdown electric field of 1.1 GV/m, which is approaching the intrinsic breakdown, in aromatic polythiourea, a new dielectric material that serves a high energy density of 23 J/cm3 as well as high charge-discharge efficiency above 90%. The molecular structure and film surface morphology were also studied, it was proved a polar amorphous phase and glass state material could significantly suppress the high field conduction to several orders smaller compared with regular polymer dielectric materials, which are usually semi-crystalline and in rubber phase.
Although moissanite has been found in various rocks, reliable primary moissanite has been reported only from kimberlites and meteorites. The Dabie Mountain moissanite reported in this paper is the first occurrence of primary moissanite hosted by serpentinite. It differs from synthetic silicon carbide in optical properties, inclusions and infrared spectrum. The biaxiality of the Dabie Mountain moissanite is thought to be the result of intracrystal deformation. In reference to the ultrahigh pressure (7—8 GPa) signature of exsolution of rod-like apatite, clinopyroxene and rutile in garnets, and magnetite lamellae in olivine reported in the Dabieshan, we inferred that the moissanite from the Dabie Mountains was probably generated at a depth of 180 km; and then subducted to a depth of 210—250 km, where the moissanite became biaxial before its exhumation.
Transmission electron microscopy (TEM), x-ray diffraction (XRD), photoluminescence (PL) and Raman scattering measurements were applied to study the correlation between the microstructure and physical properties of the GaN films grown by light radiation heating metalorganic chemical vapor deposition (LRH-MOCVD), using GaN buffer layer on sapphire substrates. When the density of the threading dislocation (TD) increases about one order of magnitude, the yellow luminescence (YL) intensity is strengthened from negligible to two orders of magnitude higher than the band edge emission intensity. The full width of half maximum (FWHM) of the GaN (0002) peak of the XRD rocking curve was widened from 11 min to 15 min, and in Raman spectra, the width of E2 mode is broadened from 5 cm−1 to 7 cm−1. A “zippers” structure at the interface of GaN/sapphire was observed by high-resolution electron microscope (HREM). Furthermore the origins of TD and relationship between physical properties and microstructures combining the growth conditions are discussed.
Transmission electron microscopy (TEM), x-ray diffraction (XRD), photoluminescence (PL) and Raman scattering measurements were applied to study the correlation between the microstructure and physical properties of the GaN films grown by light radiation heating metalorganic chemical vapor deposition (LRH-MOCVD), using GaN buffer layer on sapphire substrates. When the density of the threading dislocation (TD) increases about one order of magnitude, the yellow luminescence (YL) intensity is strengthened from negligible to two orders of magnitude higher than the band edge emission intensity. The full width of half maximum (FWHM) of the GaN (0002) peak of the XRD rocking curve was widened from 11 min to 15 min, and in Raman spectra, the width of E2 mode is broadened from 5 cm-1 to 7 cm-1. A “zippers” structure at the interface of GaN/sapphire was observed by high-resolution electron microscope (HREM). Furthermore the origins of TD and relationship between physical properties and microstructures combining the growth conditions are discussed.