Topological transition and helicity conversion of vortex torus knots and links are studied using direct numerical simulations of the incompressible Navier–Stokes equations. We find three topological transitional routes (viz. merging, reconnection and transition to turbulence) in the evolution of vortex knots and links over a range of torus aspect ratios and winding numbers. The topological transition depends not only on the initial topology but also on the initial geometry of knots/links. For small torus aspect ratios, the initially knotted or linked vortex tube rapidly merges into a vortex ring with a complete helicity conversion from the writhe and link components to the twist. For large torus aspect ratios, the vortex knot or link is untied into upper and lower coiled loops via the first vortex reconnection, with a helicity fluctuation including loss of writhe and link, and generation of twist. Then, the relatively unstable lower loop can undergo a secondary reconnection to split into multiple small vortices with a similar helicity fluctuation. Surprisingly, for moderate torus aspect ratios, the incomplete reconnection of tangled vortex loops together with strong vortex interactions triggers transition to turbulence, in which the topological helicity decomposition fails due to the breakdown of vortex core lines.

This paper, in allusion to the limitations of traditional transfer alignment methods based on the external measurement equipment or the empirical model of angular deformation, proposes a rapid and accurate transfer alignment method without relying on the empirical angular deformation model. Firstly, the relationship between the actual angular deformation and the angular velocities measured by the gyroscopes in the master and slave inertial navigation systems (INSs) is derived to roughly estimate the angular deformation. Secondly, according to the error characteristics of gyroscopes, the error model of angular deformation is established. Thirdly, expanding the angular deformation error instead of the installation error angle, flexure angle and flexure angle rate into the state vector, a low-order transfer alignment filtering model independent of the empirical angular deformation model is established. The proposed method not only gets rid of the dependence on an empirical angular deformation model, but also realises the rapid and accurate initial alignment of the slave INS without adding any external measurement equipment. The simulations and experiments evidence the validity of the proposed transfer alignment method.

We propose an improved adjoint-based method for the reconstruction and prediction of the nonlinear wave field from coarse-resolution measurement data. We adopt the data assimilation framework using an adjoint equation to search for the optimal initial wave field to match the wave field simulation result at later times with the given measurement data. Compared with the conventional approach where the optimised initial surface elevation and velocity potential are independent of each other, our method features an additional constraint to dynamically connect these two control variables based on the dispersion relation of waves. The performance of our new method and the conventional method is assessed with the nonlinear wave data generated from phase-resolved nonlinear wave simulations using the high-order spectral method. We consider a variety of wave steepness and noise levels for the nonlinear irregular waves. It is found that the conventional method tends to overestimate the surface elevation in the high-frequency region and underestimate the velocity potential. In comparison, our new method shows significantly improved performance in the reconstruction and prediction of instantaneous surface elevation, surface velocity potential and high-order wave statistics, including the skewness and kurtosis.

Somatic cell nuclear transfer (SCNT) holds vast potential in agriculture. However, its applications are still limited by its low efficiency. Histone 3 lysine 9 trimethylation (H3K9me3) was identified as an epigenetic barrier for this. Histone demethylase KDM4D could regulate the level of H3K9me3. However, its effects on buffalo SCNT embryos are still unclear. Thus, we performed this study to explore the effects and underlying mechanism of KDM4D on buffalo SCNT embryos. The results revealed that compared with the IVF embryos, the expression level of KDM4D in SCNT embryos was significantly lower at 8- and 16-cell stage, while the level of H3K9me3 in SCNT embryos was significantly higher at 2-cell, 8-cell, and blastocyst stage. Microinjection of KDM4D mRNA could promote the developmental ability of buffalo SCNT embryos. Furthermore, the expression level of ZGA-related genes such as ZSCAN5B, SNAI1, eIF-3a, and TRC at the 8-cell stage was significantly increased. Meanwhile, the pluripotency-related genes like POU5F1, SOX2, and NANOG were also significantly promoted at the blastocyst stage. The results were reversed after KDM4D was inhibited. Altogether, these results revealed that KDM4D could correct the H3K9me3 level, increase the expression level of ZGA and pluripotency-related genes, and finally, promote the developmental competence of buffalo SCNT embryos.

The dependence of fishbone cycle on energetic particle intensity has been investigated in EAST low-magnetic-shear plasmas. It is observed that the fishbone mode growth rate, saturation amplitude as well as fishbone cycle frequency clearly increase with increasing neutral beam injection (NBI) power. Moreover, enhanced electron density and temperature perturbations as well as energetic particle loss were observed with greater injected NBI power. Simulation results using M3D-K code show that as the NBI power increases, the resonant frequency and the energy of the resonant particles become higher, and the saturation amplitude of the mode also changes, due to the non-perturbative energetic particle contribution. The relationship between the calculated energetic particle pressure ratio and fishbone cycle frequency is obtained as ${f_{\textrm{FC}}} = 2.2{(1000{\beta _{\textrm{ep,calc}}} - 0.1)^{5.9 \pm 0.5}}$. Results consistent with the experimental observations have been achieved based on a predator–prey model.

In view of many problems associated with the availability of global navigation satellite system (GNSS) signals in high-altitude space, this paper presents a comprehensive and systematic analysis. First, the coverage and strength characteristics of GNSS signals in high-altitude space (i.e., space above the GNSS constellation) are presented, and the visibility of GNSS signals is evaluated by combining these two factors. Second, the geometric configuration and geometric dilution of precision (GDOP) of visible GNSS satellites are analysed. Then, the Doppler shift range of the GNSS signals is deduced based on the dynamic performance of high-altitude spacecraft. Finally, taking GaoFen-4 (GF-4) as the application object, the availability of GNSS signals is simulated and evaluated. GNSS signals in high-altitude space are generally weak, and the visible GNSS satellites are concentrated in the high-elevation range. The combination of main and side lobe signals and compatibility of multiple constellations can increase the number of visible satellites, improve the geometry configuration, reduce GDOP, and thus improve the availability of GNSS signals. The results of this research can provide technical support for the design and development of GNSS receivers suitable for high-altitude space.

A disruption database characterizing the current quench of disruptions with ITER-like tungsten divertor has been developed on EAST. It provides a large number of plasma parameters describing the predisruptive plasma, current quench time, eddy current, and mitigation by massive impurity injection, which shows that the current quench time strongly depends on magnetic energy and post-disruption electron temperature. Further, the energy balance and magnetic energy dissipation during the current quench phase has been well analysed. Magnetic energy is also demonstrated to be dissipated mainly by ohmic reheating and inductive coupling, and both of the two channels have great effects on current quench time. Also, massive gas injection is an efficient method to speed up the current quench and increase the fraction of impurity radiation.

Preoperative nutritional status plays an important role in predicting postoperative outcomes. Prognostic Nutritional Index (PNI) and Controlling Nutritional Status (CONUT) are good tools to assess patients’ nutritional status. They have been used in predicting outcomes in various malignancies, but few studies have focused on pancreatic adenocarcinoma (PDAC) patients. Totally, 306 PDAC patients were enrolled. The propensity score matching (PSM) method was introduced to eliminate the baseline inequivalence. Patients with different PNI (or CONUT) scores showed inequivalence baseline characteristics, and patients with compromised nutritional status were related with a more advanced tumour stage. After PSM, the baseline characteristics were well balanced. Both low PNI (≤45) and high CONUT (≥3) were independent risk factors for poor overall survival (P < 0·05), and the result remained the same after PSM. Survival analysis demonstrated both patients with low PNI and high CONUT score were associated with poorer survival, and the result remained the same after PSM. The results of AUC indicated that CONUT might have a higher sensitivity and specificity in predicting complications and survival. Preoperative low PNI (≤45) and high CONUT (≥3) scores might be reliable predictors of prognosis and surgical complications in PDAC patients. Compared with PNI, CONUT might be more effective.

Human milk fat is specially tailored to supply the developing infant with adequate and balanced nutrients. The present study aimed to quantify the composition of fatty acids, tocopherols and carotenoids in human milk, with special emphasis on the lactational changes. Colostrum, transitional and mature milk samples were collected longitudinally from the same forty-two healthy, well-nourished Chinese mothers. Fatty acids were quantified by GC with carotenoids (carotenes and xanthophylls) and tocopherols (α-, γ-tocopherol) determined by HPLC. Total fatty acid (TFA) content increased from 15·09 g/l in colostrum to 32·57 g/l in mature milk with the percentages of DHA and arachidonic acid (ARA) decreased. The ratio of n-6:n-3 PUFA and ARA:DHA remained constant during lactation at about 11:1 and 1·3:1, respectively. Both α-tocopherol and γ-tocopherol decreased over lactation with the ratio of α-:γ-tocopherol declined significantly from 7·21:1 to 4·21:1 (P < 0·001). Carotenoids all dropped from colostrum to mature milk as the less polar carotenes dropped by 88·67 %, while xanthophylls only dropped by 35·92 %. Lutein was predominated in both transitional and mature milk carotenoids (51·64–52·49 %), while colostrum carotenoids were mainly composed of lycopene (32·83 %) and β-carotene (30·78 %). The concentrations of tocopherols and xanthophylls but not carotenes were positively associated with TFA content in milk. These results suggested that colostrum and mature milk contained divergent lipid profiles and selective transfer mechanisms related to polarity might be involved. The present outcomes provide new insights for future breast-feeding studies, which also add in scientific evidences for the design of both initial and follow-on infant formulas.

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 transition metal compound catalysts have been taken a great part in renewable energy conversion and storage systems. Herein, we report the uniform CoFe2O4 nanoparticles with abundant oxygen vacancies and specific active surface exposed through the simple hydrothermal reaction for improving the electrocatalytic performance and stability. They show good electrocatalytic performance for hydrogen evolution reaction in 0.5 M H2SO4 with an onset potential of 20 mV, the overpotential of 45 mV (at j = 10 mA/cm2), and remarkable long-term stability more than 100 h at different current densities and better oxygen reduction reaction activity with lower overpotential in 0.1 M KOH. Moreover, the home-made primary Zn–air batteries, using CoFe2O4 nanoparticles as an air–cathode display the high open-circuit voltage of 1.47 V and the maximum power density of 142 mW/cm2. The two-series-connected batteries fabricated by CoFe2O4 nanoparticles can support a light-emitting diode to work for more than 48 h.

We propose a hybrid spectral element method for fractional two-point boundary value problem (FBVPs) involving both Caputo and Riemann-Liouville (RL) fractional derivatives. We first formulate these FBVPs as a second kind Volterra integral equation (VIEs) with weakly singular kernel, following a similar procedure in [16]. We then design a hybrid spectral element method with generalized Jacobi functions and Legendre polynomials as basis functions. The use of generalized Jacobi functions allow us to deal with the usual singularity of solutions at t = 0. We establish the existence and uniqueness of the numerical solution, and derive a hptype error estimates under L2(I)-norm for the transformed VIEs. Numerical results are provided to show the effectiveness of the proposed methods.

Why do authoritarian regimes try to improve the quality of their governance? In the absence of democratic institutions to monitor, reward and punish their performance, authoritarian politicians are normally expected to seek their self-interest through corruption and rewards to cronies, rather than providing for the public welfare. However, the Chinese state has actively promoted improved governance in recent years, with greater attention to quality of life issues to balance the primary focus on sustaining rapid economic growth. This paper analyses intra-national variation in the provision of public goods in urban China and the impact of public goods on regime support. Does better governance lead to higher levels of public support for the regime, even in the absence of democratic elections? Our evidence suggests that it does, with a greater impact for the local level than for the centre.

Current evidence of the relationship between diets and Fe status is mostly derived from studies in developed countries with Western diets, which may not be translatable to Chinese with a predominantly plant-based diet. We extracted data that were nationally sampled from the 2009 wave of China Health and Nutrition Survey; dietary information was collected using 24-h recalls combined with a food inventory for 3 consecutive days. Blood samples were collected to quantify Fe status, and log-ferritin, transferrin receptor and Hb were used as Fe status indicators. In total, 2905 (1360 males and 1545 females) adults aged 18–50 years were included for multiple linear regression and stratified analyses. The rates of Fe deficiency and Fe-deficiency anaemia were 1·6 and 0·7 % for males and 28·4 and 10·7 % for females, respectively. As red meat and haem Fe consumption differed about fifteen to twenty times throughout the five groups, divided by quintiles of animal protein intake per 4·2 MJ/d, only Fe status as indicated by log-ferritin (P=0·019) and transferrin receptor (P=0·024) concentrations in males was shown to be higher as intakes of animal foods increased. Log-ferritin was positively associated with intakes of red meat (B=0·3 %, P=0·01) and haem Fe (B=12·3 %, P=0·010) in males and with intake of non-haem Fe in females (B=2·2 %, P=0·024). We conclude that diet has a very limited association with Fe status in Chinese adults consuming a traditional Chinese diet, and a predominantly plant-based diet may not be necessarily responsible for poor Fe status.

In this study, hematite nanoparticles (α-Fe2O3 NPs) were synthesized by hydrothermal method, with morphologies (e.g., nanorhombohedra, nanobars, and nanospheres) facilely tuned by changing the concentrations of glycol in the hydrothermal solution. Then a low-cost and scalable electrophoretic deposition method was used to fabricate nanostructured α-Fe2O3 films as photoanodes for solar hydrogen generation. It was found that the film of α-Fe2O3 nanobars showed the highest photoelectrochemical (PEC) performance compared to those films of α-Fe2O3 nanorhombohedra and nanospheres, with photocurrent density reaching 0.7 mA/cm2 at 0.6 V versus Ag/AgCl. This PEC improvement may be related to the smaller diameters of nanobars shortening the carrier migration distance, reducing the recombination rate of photo-generated carriers. Moreover, all the α-Fe2O3 films showed much higher PEC performances with surface modified by Sn4+, mainly due to the reduced surface charge recombination, as the Sn4+ doped overlayer passivated surface defects. For the film of α-Fe2O3 nanobars, the photocurrent density was increased by 100%, reaching 1.4 mA/cm2 at 0.6 V versus Ag/AgCl.

The Qiangtang Metamorphic Belt (QMB) was considered to have either formed in situ by amalgmation of the North and South Qiangtang blocks or been underthrust from the Jinsha suture and exhumed in the interior of a single ‘Qiangtang Block’. A new Sphaeroschwagerina fusuline fauna discovered in the Raggyorcaka Lake area supports the interpretation that the North and South Qiangtang blocks were separated by a wide ocean during Asselian (Early Permian) time, indicating that the QMB was formed by the suturing of the Palaeotethys Ocean along the Longmu Co-Shuanghu suture.