A highly compressive effect would suppress the mixing of the shear layer in a convex wall jet. The spanwise distributed protrusions at the nozzle lip are employed to achieve mixing enhancement in this study. The mixing characteristics and enhancement mechanisms are numerically investigated by the delayed detached-eddy simulation method based on the two-equation shear-stress transport model. A widely applicable flow spatiotemporal analysis method, called proper orthogonal decomposition (POD), is used to gain further insight into the dynamical behaviours of the flow instability mode. The results reveal that the centrifugal effect maintains and amplifies the initial perturbations induced by the spanwise distributed heterogeneities, resulting in forced streamwise vortices. The instabilities induced by the streamwise vortices significantly increase the growth rate of the jet half-width and the shear layer vorticity thickness. The spanwise wavelength of the streamwise vortices is consistent with the spanwise distributed forced excitation. In addition, the spanwise meandering motion of the streamwise vortices is observed, which is usually associated with the streamwise travelling wave. This is further confirmed by the POD analysis of the spanwise velocity fluctuation in both stream-radial and stream-span sections. Also, the spatial distributions of the POD modes with the highest energy provide information on the secondary instability modes. Both sinuous and varicose types of disturbances are observed in the unforced jet, whereas the forced jet seems to be dominated by the sinuous type instability, which is more easily excited than the varicose type instability. Moreover, the turbulence intensity in the forced jet is also significantly enhanced as expected due to the earlier and stronger streamwise vortices and associated instabilities. The enhanced turbulent characteristics of the highly compressible condition tend to be isotropic, whereas in the unforced jet, it is anisotropic due to the strong compressibility suppressing the spanwise turbulent fluctuations.

We present the third data release from the Parkes Pulsar Timing Array (PPTA) project. The release contains observations of 32 pulsars obtained using the 64-m Parkes “Murriyang” radio telescope. The data span is up to 18 years with a typical cadence of 3 weeks. This data release is formed by combining an updated version of our second data release with ∼ 3 years of more recent data primarily obtained using an ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. We provide calibrated pulse profiles, flux-density dynamic spectra, pulse times of arrival, and initial pulsar timing models. We describe methods for processing such wide-bandwidth observations, and compare this data release with our previous release.

The supersonic jet over a convex wall is numerically investigated using the delayed detached-eddy simulation method based on the two-equation shear-stress transport model. The current study focuses on instabilities, turbulent statistics and the influence of compressibility effects. A widely applicable data-driven modal decomposition approach, called dynamic mode decomposition is used to gain further insight into the dynamical behaviours of the flow. The results demonstrate that streamwise vortices caused by the centrifugal force play significant roles in shear layer instabilities. The spanwise modulation of the streamwise vortices induces inflection points in the flow, resulting in secondary shear layer instability. This instability, which is sustained by the side-to-side sway of the streamwise vortices to obtain energy from the mean flow, dominates the rapid growth of the shear layer and turbulent stresses in the growth region. In the self-similar region, there is not only self-similarity of velocity profiles, but also self-similarity of normalized turbulent stresses. The compressibility effect significantly inhibits the growth of the shear layer and the formation of large-scale streamwise vortices. The investigation of turbulent stresses in the self-similar region with increasing convective Mach number indicates that the compressibility effect enhances turbulence anisotropy.

Recently, the collisionless pitch-angle scattering for relativistic runaway electrons (REs) in toroidal geometries such as tokamaks was discovered through a full orbit simulation approach (Liu et al., Nucl. Fusion, vol. 56, 2016, p. 064002), and it was then theoretically investigated that a new expression for the magnetic moment, including the second-order corrections, could essentially reproduce the so-called collisionless pitch-angle scattering process (Liu et al., Nucl. Fusion, vol. 58, 2018, p. 106018). In this paper, with synchrotron radiation, extensive numerical verification of the validity of the high-order guiding-centre theory is given for simulations involving REs by incorporating such an expression for the magnetic moment into our particle tracing code. A high-order guiding-centre simulation approach with synchrotron radiation (HGSA) is applied. Synchrotron radiation plays an essential role in the life cycle of REs. The energy of REs first increases and then becomes saturated until the electric field acceleration is balanced by the radiation dissipation. Unfortunately, the process cannot be simulated accurately with the standard guiding-centre model, i.e. the first-order guiding-centre model. Remarkably, it is found that the HGSA can effectively produce the fundamental process of REs. Since the time scale of the energy saturation of REs is close to seconds, the computational cost becomes significant. In order to save costs, it is necessary to estimate the time of energy saturation. An analytical estimate is derived for the time it takes for synchrotron drag to balance an accelerating electric field and the provided formula has been numerically verified. Test calculations reveal that HGSA is favourable for exploiting the dynamics of REs in tokamak plasmas.

Differences in pipe wall microstructure at various positions throughout the wall thickness of high strength aluminum alloy thick-wall pipes produced by reverse hot extrusion were investigated. The microstructures of the inner wall (IW), outer wall (OW), and half wall (HW) were compared. Further, heterogeneity in the mechanical properties of the pipe throughout the wall thickness was also investigated. Results revealed that the volume fraction of precipitation was highest at the HW position because of the higher Zn and Mg contents. Further, approximately 26% of grains were recrystallized in the OW position due to the greater strain during extrusion, while the recrystallization fractions of the IW and HW positions were 13% and 21%, respectively. The effects of precipitation strengthening and deformation strengthening contribute to the highest ultimate tensile strength and Vickers hardness of the HW position, and to the higher elongation of the IW and OW positions.

The overuse of antibiotics and the rapid emergence of antibiotic resistance prompted the launch of an antimicrobial stewardship programme in 2011. This study aimed to investigate the trends and correlations between antibiotic consumption and resistance of Staphylococcus aureus in a tertiary hospital of northwest China from 2010 to 2016. Trends were analysed by linear regression, and correlations were assessed by an autoregressive integrated moving average model. The total consumption of antibiotics halved during the 7-year study period, while the rates of resistance of S. aureus decreased significantly or remained stable; methicillin-resistant S. aureus (MRSA) declined markedly, from 73.3% at the beginning of the study to 41.4% by the end. This latter decrease was significantly correlated with the consumption of several classes of antibiotics. In conclusion, reduction in antibiotic use impacted significantly on resistance rates and contributed to a decline in MRSA prevalence.

Thermal-mechanical design is a time-consuming process even at its preliminary design stage. This is due to the large number of components and boundary condition data, the complexity of the geometry, and the iterative nature of the design process. The conventional design process separates the geometric and physical models and results in considerable human interventions during the design process. By assigning the breakpoints to engine assembly features as internal parameters, this article reports a novel feature-based design approach where the associated boundary conditions are represented parametrically along the feature geometric contours. They are updated automatically as per the geometrical changes, including topological changes, and hence bridging the gap between the geometric and physical models. The current approach enables data re-use of both the geometries and physical information from previous engine designs to generate new designs, dispensing with the excessive human interventions. Although the methodology is generic and applicable to other design scenarios, its capability is demonstrated in this article by some representative challenging industrial applications, sitting in the 2D preliminary gas-turbine design domain. The test cases show that the method can significantly reduce the time-cost of the iterative thermal-mechanical design flow.

Autophagy process in Toxoplasma gondii plays a vital role in regulating parasite survival or death. Thus, once having an understanding of certain effects of autophagy on the transformation of tachyzoite to bradyzoite this will allow us to elucidate the function of autophagy during parasite development. Herein, we used three TgAtg proteins involved in Atg8 conjugation system, TgAtg3, TgAtg7 and TgAtg8 to evaluate the autophagy level in tachyzoite and bradyzoite of Toxoplasma in vitro based on Pru TgAtg7-HA transgenic strains. We showed that both TgAtg3 and TgAtg8 were expressed at a significantly lower level in bradyzoites than in tachyzoites. Importantly, the number of parasites containing fluorescence-labelled TgAtg8 puncta was significantly reduced in bradyzoites than in tachyzoites, suggesting that autophagy is downregulated in Toxoplasma bradyzoite in vitro. Moreover, after treatment with drugs, bradyzoite-specific gene BAG1 levels decreased significantly in rapamycin-treated bradyzoites and increased significantly in 3-MA-treated bradyzoites in comparison with control bradyzoites, indicating that Toxoplasma autophagy is involved in the transformation of tachyzoite to bradyzoite in vitro. Together, it is suggested that autophagy may serve as a potential strategy to regulate the transformation.

Nanocolloidal crystals (NCCs) have promising applications in optical and photonic devices. However, it is critical to mechanically reinforce NCCs for device reliability, since as-synthesized NCCs are fragile due to weak interparticle bonding. Thermal sintering is currently the most common reinforcement technique; however, this method could induce serious cracking and is not suitable for temperature-sensitive materials. In this study, by characterizing silica NCCs reinforced through sintering and alumina atomic layer deposition (ALD), we find that the ALD treatment is much more effective for hardening, stiffening, and more importantly toughening NCCs. Thermally sintered NCCs are prone to indentation-induced cracking due to large residual tensile stress, significantly impairing the toughness. In contrast, the ALD treatment toughens NCCs by much over 300%. Our finding provides insights for reinforcing and toughening various nanoparticle-based and nanoporous materials.

The solidification of undercooled Ni–3.3 wt% B alloy was studied by high-speed video analysis and microstructural analysis. For moderate initial undercooling (ΔTp = 75 K), the solidification interface for primary phase transformation manifests a shape of a planar dendrite, and possesses an constant growth velocity, for eutectic transformation whereas the interface presents multi-dendrite shape and spasmodic growth, so that a constant velocity cannot describe the interface exactly. These differences suggest that primary phase solidification is controlled by far-distance diffusion while eutectic solidification by short-distance diffusion. For large initial undercooling (ΔTp = 262 K), a kinds of large “white dendrites”, which is in fact composed of multiple phases, were found in the microstructure, from inside to outside of which, the eutectic phase changes from dot phases (anomalous structure) to irregular eutectic and then to regular eutectic, indicating that the center of “white dendrites” may be the nucleation zone of eutectic reaction.

Solidification of undercooled Ni–4.5 wt% B alloy melt was investigated by glass fluxing and cyclic superheating. A maximum melt undercooling up to ΔTp = 283 K has been achieved. If ∆Tp < 175 ± 10 K, the primary solidification is L → Ni3B; the structure consists of Ni3B dendrite + lamellar eutectic; the phase sizes and fractions depend on ∆Tp. If ∆Tp ≥ 175 ± 10 K, the primary solidification is L → Ni/Ni23B6; the structure consists of the dot-phase region + the anomalous eutectic/network boundary; the phase fractions mainly depend on ∆Tr; the dot phases are determined as rod eutectic and dot precipitates, while the network boundary is the divorced eutectic. The solidification pathways show that there is a common critical nucleation temperature, 1227 ± 10 K, for metastable eutectic reaction in hypoeutectic and hypereutectic Ni–Ni3B alloys.

Solidification of undercooled Ni–3.3 wt% B alloy melt was investigated by glass fluxing. If ΔTe < 140 ± 10 K, two recalescences appear, indicating that stable eutectic reaction occurs; if ΔTe ≥ 140 ± 10 K, three recalescences can be observed, indicating that metastable eutectic reaction occurs. Analysis indicates that the phase fractions of the as-solidified structure can be predicted by the recalescence delay times in the cooling curves. High-speed video images show that the solidification interface of primary solidification changes from single dendritic shape to spherical shape with increasing ΔTp; the interface of eutectic solidification changes from many small “dendrites” to a single large one with increasing ΔTe; the interface of residual liquid solidification changes from many small rings to a single large one with increasing ΔTr. The growth velocity of eutectic solidification suggests a coupled growth at small and moderate undercoolings and decoupled growth at large undercooling, whereas that of residual liquid solidification cannot be interpreted by the available models.

KLa2Ti3O9.5 and KLa2Ti3O9.5:Er3+ nanocrystals were successfully synthesized using a hydrothermal method and a subsequent calcination treatment. The band gap (Eg) of the KLa2Ti3O9.5 nanocrystals was calculated to be about 2.56 eV by means of the reflectance diffusion technique. Under 980-nm excitation, the KLa2Ti3O9.5:Er3+ nanocrystals emitted intense green (2H11/2/4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) upconversion (UC) luminescence. In comparison with pure KLa2Ti3O9.5, the KLa2Ti3O9.5:Er3+ nanocrystals exhibited a higher activity for water splitting into H2 under simulated solar light irradiation. We suggest that the enhancement of photocatalytic activity is related to the Brunauer-Emmett-Teller (BET) surface area and UC luminescence of KLa2Ti3O9.5:Er3+.

Novel hydrogels composed of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) macromolecules were formed by photopolymerization. PFS chains bearing acrylate side groups were copolymerized with NIPAM and N,N’-methylenebisacrylamide in tetrahydrofuran in a predetermined ratio under ultraviolet light-emitting diode (UV-LED) irradiation at a wavelength of 365 nm, in the presence of a photoinitiator. Crosslinking occurred smoothly, providing homogeneous hydrogels. The equilibrium swelling ratio, rheology and morphology of these hybrid PNIPAM-PFS-based hydrogels were investigated. In-situ fabrication of silver nanoparticles inside the hydrogel network via reduction of silver nitrate by the PFS chains led to hydrogel composites. These composites showed strong antimicrobial activity while maintaining a high biocompatibility with cells.

Retinal pigment epithelium (RPE) cells are vital for retinal health. However, they are susceptible to injury with ageing and exposure to excessive light, including UV (100–380 nm) and visible (380–760 nm) radiation. To evaluate the protective effect of blueberry anthocyanins on RPE cells, in vitro cell models of replicative senescent and light-induced damage were established in the present study. After purification and fractionation, blueberry anthocyanin extracts (BAE) were yielded with total anthocyanin contents of 31·0 (sd 0·5) % and were used in this study. Replicative senescence of RPE cells was induced by repeatedly passaging cells from the fourth passage to the tenth. From the fifth passage, cultured RPE cells began to enter a replicative senescence, exhibiting reduced cell proliferation along with an increase in the number of β-galactosidase-positive cells. RPE cells maintained high cell viability (P < 0·01) and a low (P < 0·01) percentage of β-galactosidase-positive cells when treated with 0·1 μg/ml BAE. In contrast, after exposure to 2500 (sd 500) lx light (420–800 nm) for 12 h, RPE cells in the positive control (light exposure, no BAE treatment) exhibited premature senescence, low (P < 0·01) cell viability and increased (P < 0·01) vascular endothelial growth factor (VEGF) release compared with negative control cells, which were not subjected to light irradiation and BAE exposure. Correspondingly, BAE is beneficial to RPE cells by protecting these cells against light-induced damage through the suppression of ageing and apoptosis as well as the down-regulation of the over-expressed VEGF to normal level. These results demonstrate that BAE is efficacious against senescence and light-induced damage of RPE cells.

Increasing attention has been paid to Spirulina for its potential clinical uses. The present study investigated the protection by dietary Spirulina platensis against d-galactosamine (d-GalN)- and acetaminophen (APAP)-induced hepatitis in ICR mice. Mice in each group (n 6) were fed with a standard diet (American Institute of Nutrition (AIN)-93G), a positive control diet containing 0·5 % butylated hydroxytoluene (BHT), or a diet containing 3, 6 or 9 % S. platensis for 1 week. On the last day the mice were treated with d-GalN (300 mg/kg body weight, intraperitoneally) or APAP (150 mg/kg body weight, intraperitoneally) and 24 h later the mice were killed. The doses of both 6 and 9 % S. platensis were found to significantly alleviate the increase of serum glutamate oxaloacetoacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) activities in d-GalN- or APAP-intoxicated mice. The observation was very similar to that of the positive control groups. Two more experiments were carried out to investigate the involvement of thiobarbituric acid-reactive substances (TBARS) and IL-18 in the suppression of 6 % S. platensis on d-GalN- and APAP-induced hepatitis. The significant increase of GOT and GPT activities was found to be accompanied with the elevation of hepatic TBARS level, IL-18 mRNA expression and serum IL-18 concentration, and was significantly alleviated by supplementation with 6 % S. platensis in diets. These results showed that dietary S. platensis could provide a significant protection against d-GalN- and APAP-induced liver injuries, and IL-18 and lipid peroxidation might be involved in the protective influence of S. platensis.

The genetic diversities of 72 individuals from three wild Lenok populations of Mudanjiang River (MD), Yalujiang River (YL) and Wusulijiang River (WSL) in the northeast of China were analysed using amplified fragment length polymorphism (AFLP) markers. The results showed that 541 polymorphic loci out of 559 were amplified by 12 primer pairs and the percentage of polymorphic loci was 96.78%. Shannon indices for the MD, YL and WSL populations were 0.3988±0.2913, 0.3254±0.3037, 0.2125±0.2862, respectively, and Nei's gene diversity indices were 0.2737±0.2062, 0.2229±0.2129, 0.1446±0.1985, respectively. The average total genetic diversity (Ht) was 0.3512±0.0.0208 and the average genetic diversity within populations (Hs) was 0.2137±0.0152. Among the three populations, the average genetic distance (Dst) was 0.1375 and the gene differentiation coefficient (Gst) was 0.3914. The genetic diversity was 60.85% within populations and 39.15% among populations. The gene flow index (Nm) was 0.7776. The analysis of molecular variance (AMOVA) indicated that the average fixation index (Fst) was 0.55336. The variance was 55.16% within populations and 44.84% among populations. The highest polymorphism ratio was in the MD group and the lowest in the WSL group.