Acoustic resonances in cascade structures may cause structural damage and instability problems in aero-engines and other industrial plants; thus, developing corresponding prediction methods is important. However, works published in the open literature mostly focus on the special case of the stationary Parker modes and provide little knowledge into the rotating resonances in annular cascades, especially in the presence of non-zero background mean flows. This paper develops a three-dimensional semi-analytic model to study the acoustic resonances in an annular cascade in the presence of axial mean flow. The model applies an unsteady cascade response based on the three-dimensional lifting surface method to construct a matrix equation. Characteristic frequencies are solved in the complex domain by numerically searching for singular points. Both the oscillation frequency and the growth rate of the three-dimensional resonance modes are theoretically calculated for the first time under non-zero mean flow conditions. The results reveal an organised distribution with varying inter-blade phase angle and show obvious change with the background flow speed. It is found that the unsteady vortex shedding from the trailing edges of the cascade is a key factor influencing the dissipation rate of the resonance modes. In addition, the important effects of acoustic scattering by the cascade during resonances are examined, which qualitatively corroborate some previous experimental observations.

By integrating the theory of purposeful work behavior with the person-environment (P-E) fit literature, we employ a bilateral approach to examine how employee-supervisor congruence in purposeful work striving (i.e., achievement striving) influences employee voice behavior via an internal motivation mechanism (i.e., organizational identification). Using polynomial regressions with response surface modeling, we analyze data from 827 employees and their 197 supervisors in two studies. The results show that achievement-driven employees are more likely to speak up when employee-supervisor achievement striving is congruent, regardless of whether it is high or low. Furthermore, employee-supervisor congruence in achievement striving enhances employees’ felt oneness with the organization and organizational identification, which in turn fuels their voice behavior. We conclude with theoretical and practical implications.

Currently, there is an increasing demand for parallel mechanisms with fewer inputs and more outputs in aerospace, antennas, and recreational facilities. Therefore, this paper proposes a new parallel mechanism (PM) with a separation of constraints and drives, facilitating centralized drive management. Based on screw theory, the type synthesis of new parallel mechanisms with 3T (T representing translation), 3R (R representing revolute), 2T1R, and 2R1T is proposed. Three-degree-of-freedom (3-DOF) parallel mechanisms with fewer inputs and multiple outputs are proposed. Taking the 3RPS-PPPS parallel mechanism as an example, the closed-loop vector method is employed to solve for the lengths of actuated branches. A complete Jacobi matrix is constructed. The motion/force transmission performance of the 3RRS/PPPS parallel mechanism is better than the 3RRS parallel mechanism. Centralized management of drive branches greatly reduces the number of drives, making maintenance and repair easier. It has many application scenarios in antennas, recreational facilities, and other occasions.

Most natural and synthetic rubbers have inherently high flammability, a property which limits their uses. The aim of the present work was to study the effect of organo-montmorillonite (OMMT) and modified OMMT on the flame-retardance and mechanical properties of natural rubber (NR) composites. The OMMT was modified with hyper-branched polymer via condensation polymerization between the intercalation agent, N,N-di(2-hydroxyethyl)-N-dodecyl-N-methylammonium chloride, and the monomer, N,N-dihydroxyl-3-aminomethyl propionate. This modified OMMT was then reacted with phosphate, and a novel flame-retardant hyper-branched organic montmorillonite (FR-HOMMT) was thus obtained. The surface morphology, interlayer space, interlamellar structure, and thermal properties of these modified clays were investigated by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. The FR-HOMMT showed increased basal spacing and better thermal stabilities due to the different arrangement and thermal stability of the novel organic macromolecular surfactant. Natural rubber NR/OMMT and NR/FR-HOMMT composites were prepared by conventional compounding with OMMT and the phosphorus-based organo-montmorillonite. The cure characteristics, tensile strength, wear resistance, thermal stabilities, and flame-retardant properties were researched and compared. The best dispersion of this modified clay was observed for 20 phr (parts per hundred of rubber) of FR-HOMMT-filled composite, which resulted in the best mechanical performance with an increase of 47% in tensile strength, of 40% in elongation at break, and decrease of 140% in abrasion loss compared with 20 phr of the OMMT-filled matrix. A mechanism for reinforcing and flame retardance is proposed here. The 'anchor' effect caused by the hyper-branched polymer may decrease the number and size of the voids in the NR matrix, and thus increase the crack path during tensile drawing. Meanwhile, the flame retardance of the OMMT and the phosphate may increase the number of carbonaceous layers, thus inhibiting the degree of pyrolysis of the NR matrix during burning.

The objective of this study was to understand and measure epigenetic changes associated with the occurrence of CHDs by utilizing the discordant monozygotic twin model. A unique set of monozygotic twins discordant for double-outlet right ventricles (DORVs) was used for this multiomics study. The cardiac and muscle tissue samples from the twins were subjected to whole genome sequencing, whole genome bisulfite sequencing, RNA-sequencing and liquid chromatography-tandem mass spectrometry analysis. Sporadic DORV cases and control fetuses were used for validation. Global hypomethylation status was observed in heart tissue samples from the affected twins. Among 36,228 differentially methylated regions (DMRs), 1097 DMRs involving 1039 genes were located in promoter regions. A total of 419 genes, and lncRNA–mRNA pairs involved 30 genes, and 62 proteins were significantly differentially expressed. Multiple omics integrative analysis revealed that five genes, including BGN, COL1A1, COL3A1, FBLN5, and FLAN, and three pathways, including ECM-receptor interaction, focal adhesion and TGF-β signaling pathway, exhibited differences at all three levels. This study demonstrates a multiomics profile of discordant twins and explores the possible mechanism of DORV development. Global hypomethylation might be associated with the risk of CHDs. Specific genes and specific pathways, particularly those involving ECM–receptor interaction, focal adhesion and TGF–β signaling, might be involved in the occurrence of CHDs.

How do corporate political ties impact firm performance in a transition economy? This topic has attracted wide attention in the strategy field. Accordingly, our study replicates a highly influential study, ‘Managerial ties and firm performance in a transition economy: The nature of a micro-macro link’ (Peng & Luo, 2000). The original study found that managerial political ties greatly improve organizational performance, and that this ‘micro-macro’ link varies across ownership types, business sectors, firm sizes, and industry growth rates. This replication study offers a hierarchical view of political ties by extending it from the individual to the organizational level and explores the complex link between the two levels of corporate political ties and firm performance. The results of a staged quasi-replication exercise show some similarities with the original study in the mechanism of corporate political ties on firm performance but, more importantly, reveal some key differences in the effect size and contingent effects. Furthermore, an extended test shows that corporate political ties are multilevel, and different levels of political ties vary in their mechanisms and effects on firm performance. The findings reveal temporal and contextual sensitivities of political ties studies in transition economies.

Breast milk leptin plays a potential role in preventing childhood obesity. However, the associations of breast milk leptin with maternal metabolism in pregnancy and dietary patterns during lactation are still unclear. We aimed to explore associations of breast milk leptin with maternal metabolic profiles in pregnancy and dietary patterns during lactation. A total of 332 participants were recruited for this retrospective cohort study. Breast milk samples were collected at approximately 6 weeks postpartum. Breast milk leptin and twenty-three metabolic profiles in pregnancy were measured in this study. A semi-quantitative FFQ was used to gather dietary information during lactation. Both principal component analysis and the diet balance index were used to derive dietary patterns. Among twenty-three maternal metabolic profiles, maternal serum glucose (β = 1·61, P = 0·009), γ-glutamyl transferase (β = 0·32, P = 0·047) and albumin (β = −2·96, P = 0·044) in pregnancy were correlated with breast milk leptin. All dietary patterns were associated with breast milk leptin. Given the joint effects of maternal metabolism in pregnancy and dietary patterns during lactation, only diet quality distance was significantly associated with leptin concentrations in breast milk (low level v. almost no diet problem: β = −0·46, P = 0·011; moderate/high level v. almost no diet problem: β = −0·43, P = 0·035). In conclusion, both maternal metabolism in pregnancy and dietary patterns during lactation were associated with breast milk leptin. Maternal diet balance during lactation was helpful to improve breast milk leptin concentration.

We consider the stability of laminar high-Reynolds-number flow through a planar channel formed by a rigid wall and a heavy compliant wall under longitudinal tension with motion resisted by structural damping. Numerical simulations indicate that the baseline state (with Poiseuille flow and a flat wall) exhibits two unstable normal modes: the Tollmien–Schlichting (TS) mode and a surface-based mode which manifests as one of two flow-induced surface instabilities (FISI), known as travelling wave flutter (TWF) and static divergence (SD), respectively. In the absence of wall damping the system is unstable to TWF, where the neutrally stable wavelength becomes shorter as the wall mass increases. With wall damping, TWF is restricted to long wavelengths through interaction with the most unstable centre mode, while for wall damping greater than a critical value the system exhibits an SD mode with a two branch neutral stability curve; the critical conditions along the upper and lower branches are constructed in the limit of large wall damping. We compute the Reynolds–Orr and activation energy descriptions of these neutrally stable FISI by continuing the linear stability analysis to the following order in perturbation amplitude. We find that both FISI are primarily driven by the working of normal stress on the flexible wall, lower-branch SD has negative activation energy, while upper-branch SD approaches zero activation energy in the limit of large wall damping. Finally, we elucidate interaction between TS and TWF modes for large wall mass, resulting in stable islands within unstable regions of parameter space.

Patients with cirrhosis experience worse health-related quality of life (HRQoL), and attempts are warranted further exploration of modifiable factors to improve HRQoL. Data on the impact of malnutrition risk on HRQoL among cirrhosis are limited; thus, we aimed to strengthen understanding by clarifying the relationship between nutritional status and low HRQoL in patients with decompensated cirrhosis. Consecutive inpatients with cirrhosis attending our department within a tertiary hospital were studied. Generic health profiles and malnutrition risk were evaluated by the EuroQol-5D (EQ-5D) and Royal Free Hospital-Nutritional Prioritizing Tool (RFH-NPT) score, respectively. Multiple linear regression analysis was used to determine association of malnutrition risk with low HRQoL. In this cohort of 364 patients with median age of 64 years and 49·5 % male, 55·5 % of the study population reported impairment pertinent to HRQoL in at least one dimension in terms of the EQ-5D. Moreover, malnutrition risk (RFH-NPT score: β coefficient = −0·114, P = 0·038) was proved to be independently associated with poor HRQoL in multiple analysis, after adjustment for significant variables like age, BMI and markers of decompensation. Notably, we found that health dimensions representing physical function (i.e. mobility, self-care and usual activities) are substantially affected, while malnourished patients reported less frequencies of complaints in other domain such as anxiety/depression. In conclusion, the risk of malnutrition assessed by the RFH-NPT score is independently associated with low HRQoL. It is operational to improve HRQoL by identifying patients at high malnutrition risk and providing timely nutrition treatment.

In the last five years, the number of periodic variable stars has increased by two million. We used the ZTF DR2 data to find and build a catalog that includes 780,000 periodic variable stars. These periodic variable stars were classified into 11 types, which greatly complemented the variable stars in Galactic disk. Based on the latest ZTF DR16 data, we found 2 million variable candidates. We trained a machine learner to classify variable stars, and the learner had a prediction accuracy of 94%. Using millions of variable stars, we carried out studies to optimize the period–luminosity relations and the Galactic structure and the extinction law. With the future China Space Station Telescope, millions of variable stars in the Local Group will be discovered. They help to study the structure of our Local Group and also to cross-check the distance ladders based on different variable stars.

One novel trend in reducing aero-engine noise is to utilize the silent flight mechanism of owls by applying perforations on fan stator vanes. Consequently, the establishment of relevant theoretical models is of particular interest. The current efforts made in this regard are just targeting the features based on two-dimensional models without including the three-dimensionality. In this paper, we present a three-dimensional solution for acoustic scattering by annular perforated cascades, and the dipole source corresponding to the unsteady pressure loading on the vanes is identified as the dominant sound source. By the singularity method, the acoustic response is obtained with the soft boundary condition applied on the vane surfaces. It is found that considerable noise reduction can be achieved for rotor–stator interaction with a modest uniform porosity, and accordingly two mechanisms are proposed to understand the effect of porosity on propagating sound. The first is that the perforations allowing a normal velocity across the vane reduce the unsteady loading induced by the incident disturbances. The second is that the three-dimensional interactions among the dipole sources at different positions are also dampened by the soft boundaries, thus the distribution of the unsteady pressure loading on the vanes will also change significantly compared to hard-vane cases. Non-uniform distributions of porosity are investigated further, indicating that perforations in the vane upstream area are more effective in reducing propagating noise. Our method is fully three-dimensional and capable of investigating non-uniform porosity, and thus is able to provide useful guidance for future soft vane designs.

Fibronectin type III domain-containing protein 5 (FNDC5) is a transmembrane protein and the precursor of irisin, which serves as a systemic exerkine/myokine with multiple origins. Since its discovery in 2012, this hormone-like polypeptide has rapidly evolved to a component significantly involved in a gamut of metabolic dysregulations and various liver diseases. After a decade of extensive investigation on FNDC5/irisin, we are still surrounded by lots of open questions regarding its diagnostic and therapeutic values. In this review, we first concentrated on the structure–function relationship of FNDC5/irisin. Next, we comprehensively summarised the current knowledge and research findings regarding pathogenic roles/therapeutic applications of FNDC5/irisin in the context of non-alcoholic fatty liver disease, fibrosis, liver injury due to multiple detrimental insults, hepatic malignancy and intrahepatic cholestasis of pregnancy. Moreover, the prominent molecules involved in the underlying mechanisms and signalling pathways were highlighted. As a result, emerging evidence reveals FNDC5/irisin may act as a proxy for diagnosing liver disease pathology, a sensitive biomarker for assessing damage severity, a predisposing factor for surveilling illness progression and a treatment option with protective/preventive impact, all of which are highly dependent on disease grading and contextually pathological features.

Over-the-rotor liner exhibits the potential to further attenuate turbofan noise, but the physics involved remain to be explored. In this paper, a three-dimensional coupled singularity method is proposed to investigate the flow-acoustic coupling effects of axially overlapping annular rotor and finite-length liner in subsonic flow. The formulation adopts the orthogonal basis expansion of the generated disturbances in terms of the hard-walled duct modes. The sound scatterings at the rotor and the liner are then characterized, respectively, by the underdetermined dipole and monopole distributions. We derive a simultaneous solution to the coupled unsteady rotor and liner responses, which ensures that the resultant perturbed field satisfies both the impermeable boundary condition on the blade surfaces and the impedance boundary condition on the lined wall. The effect of a perforated porous-material liner on the wake–rotor interaction tones is investigated. The analysis reveals that for the sound field of varying mode and frequency characteristics, moving the inlet liner to the over-the-rotor location generally leads to limited loss or even an increase of upstream sound absorption, along with additional acoustic benefits in the aft duct. The flow-acoustic coupling between the axially overlapping rotor and liner is shown to alleviate significantly the unsteady blade loading and meanwhile intensify the fluid particle oscillation through the acoustically treated wall. Sound source reduction and sound dissipation enhancement are thus identified as the governing noise attenuation mechanisms. Finally, we extend the analysis to provide insights into the effectiveness of over-the-rotor acoustic treatment with shortened axial length.

The mumps resurgence has frequently been reported around the world in recent years, especially in many counties mumps vaccines have been widely used. This study aimed to describe the spatial epidemiological characteristics of mumps in Jiangsu, and provide a scientific basis for the implementation and adjustment of strategies to prevent and control mumps. The epidemiological characteristics were described with ratio or proportion. Spatial autocorrelation, Tango's flexible spatial scan statistics, and Kulldorff's elliptic spatiotemporal scan statistics were applied to identify the spatial autocorrelation, detect hot and cold spots of mumps incidence, and aggregation areas. A total of 172 775 cases were reported from 2004 to 2020 in Jiangsu. The general trend of mumps incidence is declining with a bimodal seasonal distribution identified mainly in summer and winter, respectively. Children aged 5–10 years old are the main risk group. A migration trend of hot spots from southeast to northwest over time was found. Similar high-risk aggregations were detected in the northwestern parts through spatial-temporal analysis with the most likely cluster time frame around 2019. Local medical and health administrations should formulate and implement targeted health care policies and allocate health resources more appropriately corresponding to the epidemiological characteristics of mumps.