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To evaluate the effects of gestational weight gain (GWG) in the first trimester (GWG-F) and the rate of gestational weight gain in the second trimester (RGWG-S) on gestational diabetes mellitus (GDM), exploring the optimal GWG ranges for the avoidance of GDM in Chinese women.
A population-based prospective study was conducted. Gestational weight was measured regularly in every antenatal visit and assessed by the Institute of Medicine (IOM) criteria (2009). GDM was assessed with the 75-g, 2-h oral glucose tolerance test at 24–28 weeks of gestation. Multivariable logistic regression was performed to assess the effects of GWG-F and RGWG-S on GDM, stratified by pre-pregnancy BMI. In each BMI category, the GWG values corresponding to the lowest prevalence of GDM were defined as the optimal GWG range.
Pregnant women (n 1910) in 2017.
After adjusting for confounders, GWG-F above IOM recommendations increased the risk of GDM (OR; 95 % CI) among underweight (2·500; 1·106, 5·655), normal-weight (1·396; 1·023, 1·906) and overweight/obese women (3·017; 1·118, 8·138) compared with women within IOM recommendations. No significant difference was observed between RGWG-S and GDM (P > 0·05) after adjusting for GWG-F based on the previous model. The optimal GWG-F ranges for the avoidance of GDM were 0·8–1·2, 0·8–1·2 and 0·35–0·70 kg for underweight, normal-weight and overweight/obese women, respectively.
Excessive GWG in the first trimester, rather than the second trimester, is associated with increased risk of GDM regardless of pre-pregnancy BMI. Obstetricians should provide more pre-emptive guidance in achieving adequate GWG-F.
The microbiota–gut–brain axis, especially the microbial tryptophan (Trp) biosynthesis and metabolism pathway (MiTBamp), may play a critical role in the pathogenesis of major depressive disorder (MDD). However, studies on the MiTBamp in MDD are lacking. The aim of the present study was to analyze the gut microbiota composition and the MiTBamp in MDD patients.
We performed shotgun metagenomic sequencing of stool samples from 26 MDD patients and 29 healthy controls (HCs). In addition to the microbiota community and the MiTBamp analyses, we also built a classification based on the Random Forests (RF) and Boruta algorithm to identify the gut microbiota as biomarkers for MDD.
The Bacteroidetes abundance was strongly reduced whereas that of Actinobacteria was significantly increased in the MDD patients compared with the abundance in the HCs. Most noteworthy, the MDD patients had increased levels of Bifidobacterium, which is commonly used as a probiotic. Four Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologies (KOs) (K01817, K11358, K01626, K01667) abundances in the MiTBamp were significantly lower in the MDD group. Furthermore, we found a negative correlation between the K01626 abundance and the HAMD scores in the MDD group. Finally, RF classification at the genus level can achieve an area under the receiver operating characteristic curve of 0.890.
The present findings enabled a better understanding of the changes in gut microbiota and the related Trp pathway in MDD. Alterations of the gut microbiota may have the potential as biomarkers for distinguishing MDD patients form HCs.
Direct numerical simulation of the Navier–Stokes equations is carried out to investigate the interaction of a conical shock wave with a turbulent boundary layer developing over a flat plate at free-stream Mach number
and Reynolds number
, based on the upstream boundary layer momentum thickness. The shock is generated by a circular cone with half opening angle
. As found in experiments, the wall pressure exhibits a distinctive N-wave signature, with a sharp peak right past the precursor shock generated at the cone apex, followed by an extended zone with favourable pressure gradient, and terminated by the trailing shock associated with recompression in the wake of the cone. The boundary layer behaviour is strongly affected by the imposed pressure gradient. Streaks are suppressed in adverse pressure gradient (APG) zones, but re-form rapidly in downstream favourable pressure gradient (FPG) zones. Three-dimensional mean flow separation is only observed in the first APG region associated with the formation of a horseshoe vortex, whereas the second APG region features an incipient detachment state, with scattered spots of instantaneous reversed flow. As found in canonical geometrically two-dimensional wedge-generated shock–boundary layer interactions, different amplification of the turbulent stress components is observed through the interacting shock system, with approach to an isotropic state in APG regions, and to a two-component anisotropic state in FPG. The general adequacy of the Boussinesq hypothesis is found to predict the spatial organization of the turbulent shear stresses, although different eddy viscosities should be used for each component, as in tensor eddy-viscosity models, or in full Reynolds stress closures.
This study examines the relationship between filial piety (adult children's filial behaviours and attitudes as well as elderly mothers’ overall evaluation of children's filial piety) and elderly mothers’ reports of intergenerational ambivalence (positive feelings, negative feelings and combined ambivalence) in rural China. We analysed the data from a survey in 2016 covering 2,203 adult children and 802 elderly mothers in Sichuan Province using a two-level mixed-effects modelling analysis. The results indicate that most components of filial piety are associated with mothers’ ambivalence, in that less ambivalence was reported by mothers when their adult children provided more emotional support to, had less conflict with and were evaluated as more filial by their mothers. Interestingly, mothers demonstrated greater positive feelings when their children were more filial in behaviour and attitude, but they also reported greater negative feelings and ambivalence when their children were more obedient, implying that absolute obedience to elderly parents might no longer be accepted by people. These findings may provide further understanding about the correlation between the culture of filial piety and intergenerational relationships in rural China.
Repetitive motion planning and control (RMPC) is a significant issue in the research of redundant robot manipulators. Moreover, noise from rounding error, truncation error, and robot uncertainty is an important factor that greatly affects RMPC schemes. In this study, the RMPC of redundant robot manipulators in a noisy environment is investigated. By incorporating the proportional and integral information of the desired path, a new RMPC scheme with pseudoinverse-type (P-type) formulation is proposed. Such a P-type RMPC scheme possesses the suppression of constant and bounded time-varying noises. Comparative simulation results based on a five-link robot manipulator and a PUMA560 robot manipulator are presented to further validate the effectiveness and superiority of the proposed P-type RMPC scheme over the previous one.
Swelling deformation tests of Kunigel bentonite and its sand mixtures were performed in distilled water and NaCl solution. The salinity of NaCl solution has a significant impact on the swelling properties of bentonite, but not on its surface structure. The surface structure was characterized using the fractal dimension Ds. Based on the fractal dimension, a unique curve of the em–pe relationship (em is the void ratio of montmorillonite and pe is the effective stress) at full saturation was introduced to express the swelling deformation of bentonite–sand mixtures. In mixtures with a large bentonite content, the swelling deformation always followed the em–pe relationship. In mixtures with a small bentonite content, when the effective stress reached a threshold, the void ratio of montmorillonite em deviated from the unique em–pe curve due to the appearance of a sand skeleton. The threshold of vertical pressure for mixtures in different solutions and the maximum swelling strains were estimated using the em–pe relationship. The good agreement between estimates and experimental data suggest that the em–pe relationship might be an alternative method for predicting the swelling deformation of bentonite–sand mixtures in salt solution.
Residual strain often occurs in metal when it was subjected to the tension load, random vibration, or high impact. The mild steel was selected as the research object, and the feasibility of using nonlinear ultrasonic technique to characterize the residual strain was investigated in this paper. First, the mild steel specimens were stretched to several different kinds of stress, then the nonlinear effect as well as the microstrain of each sample was measured. The results indicate that the microstrain increases with increasing applied stress and reaches a maximum value of about 0.036% as the tensile stress increases to the elastic limit. Compared with the original specimen, the nonlinear parameter of tensile specimen gradually increased within the elastic limit. This result reveals that the variation of nonlinear parameter was related to microstrain in mild steel, because the microstructure observation demonstrated that the dislocation structure was basically unchanged within the elastic limit. This research indicates that the nonlinear ultrasonic method has the promising potential to characterize the microstrain in metals.
Paediatric Mycoplasma pneumoniae pneumonia (MPP) is a major cause of community-acquired pneumonia in China. Data on epidemiology of paediatric MPP from China are little known. This study retrospectively collected data from June 2006 to June 2016 in Beijing Children's Hospital, Capital Medical University of North China and aims to explore the epidemiological features of paediatric MPP and severe MPP (SMPP) in North China during the past 10 years. A total of 27 498 paediatric patients with pneumonia were enrolled. Among them, 37.5% of paediatric patients had MPP. In this area, an epidemic took place every 2–3 years at the peak, and the positive rate of MPP increased during these peak years over time. The peak age of MPP was between the ages of 6 and 10 years, accounting for 75.2%, significantly more compared with other age groups (χ2 = 1384.1, P < 0.0001). The epidemics peaked in September, October and November (χ2 = 904.9, P < 0.0001). Additionally, 13.0% of MPP paediatric patients were SMPP, but over time, the rate of SMPP increased, reaching 42.6% in 2016. The mean age of paediatric patients with SMPP (6.7 ± 3.0 years old) was younger than that of patients with non-SMPP (7.4 ± 3.2 years old) (t = 3.60, P = 0.0001). The prevalence of MPP and SMPP is common in China, especially in children from 6 to 10 years old. Paediatric patients with SMPP tend to be younger than those with non-SMPP. MPP outbreaks occur every 2–3 years in North China. September, October and November are the peak months, unlike in South China. Understanding the epidemiological characteristics of paediatric MPP can contribute to timely treatment and diagnosis, and may improve the prognosis of children with SMPP.
Culture, mainly defined as values and beliefs, has recently attracted much attention in economics. Cultural practices receive less attention, as emphasized in anthropology. We argue that the notion of ‘ritual’ can enrich economic research on culture as a specific form of socially standardized interactions that create shared contexts and emotions to build mutual trust and community. China is an important case in point, because ritual is a central concern in common interpretations of traditional Chinese culture. We look at practices of Chinese entrepreneurs that activate rituals in various settings. We conclude that these phenomena can be analytically condensed in the cultural complex of a ‘ritual economy’.
The preparation of three-dimensional honeycomb nitrogen-doped carbon materials (3D-HNCMs) which can be used as electrode materials for supercapacitors is reported. The composites with the 3D honeycomb structure exhibited better electrochemical performance, and the structure and properties were proved by various means, such as SEM, TEM, IR, N2 sorption, XRD and XPS. Used as electrode materials for supercapacitors in the KOH electrolyte, 3D-HNCMs displayed a significantly high specific capacitance (409 F/g at a current of 0.5 A/g). Moreover, the 3D-HNCM electrode exhibited superior electrochemical performance, such as excellent cycling stability (98% capacitance retention after 10,000 cycles), a maximum energy density of 15.37 W h/kg, a maximum power density of 40.3 kW/kg, and low equivalent series resistance (2.1 Ω). Particularly, the electrochemical characteristic of 3D-HNCMs could be attributed to the synergistic effect of a high surface area, unique microporous and mesoporous structure, and nitrogen atom doping. These carbon materials with unique structure are promising electrode materials for future supercapacitor application.
Robots often need to accomplish some complex tasks such as surveillance, response and obstacle avoidance. In this paper, a dynamic search method is proposed to generate optimal robot trajectories satisfying complex task requirement in uncertain environment. The LTL-A* algorithm is presented to generate a global optimal path and the A* algorithm is provided to modify the global optimal path. The task is specified by a linear temporal logic (LTL) formula, and a weighted transition system according to the known information in uncertain environment is modeled to describe the robot motion. Subsequently, a product automaton is constructed by combining the transition system with the task requirement. Based on the product automaton, the LTL-A* algorithm is proposed to generate a global optimal path. The local path planning based on the A* algorithm is employed to deal with the environment change during the process of tracking the global optimal path for the robot. The results of the simulation and experiments show that the proposed method can not only meet the complex task requirement in uncertain environment but also improve the search efficiency.
The status-legitimacy hypothesis proposes that low-status groups are more inclined to justify the status quo as fair and legitimate than high-status groups. Although there are some research evidences for this hypothesis, many studies have found the opposite result, that disadvantaged groups are more dissatisfied with the social system. To resolve this disagreement, this article integrates relevant ideas and empirical research in three aspects. First, the conceptual approach emphasises that the controversy is a result of different operational definitions of social status and system justification in previous studies. The second approach, focusing on moderator variables, proposes that the disputes over past studies are probably due to moderator variables, which can influence the relationship between status and system justification. The third approach, based on psychological mechanisms, proposes that system justification theory cannot completely explain the psychological underpinnings of status differences in system justification, and in order to clarify this, it is necessary to explore other psychological processes. Future studies should continue to examine the mediation mechanisms and boundary conditions of the status-legitimacy hypothesis and may try to establish a nonlinear hypothesis. Moreover, researchers should also pay attention to the application of experimental methods and big-data methods.
Goaty flavor and poor consistency may impact consumer acceptance of fermented goat milk. The undesirable characteristics can mainly be attributed to the presence of short-medium chain free fatty acid (SM-FFA) especially C6-C10 fatty acids and low αs1-casein content in goat milk. This study aimed to investigate the effects of polymerized whey protein (PWP) on goaty flavor as well as the texture properties of fermented goat milk in comparison with β-cyclodextrin (β-CD). Samples were evaluated on sensory properties, SM-FFA contents, texture, and apparent viscosity. Compared with control, the fatty acids contents (C6, C8, C10) decreased significantly in fermented goat milk with 0·5% β-CD (22, 71, 54%, respectively) and with 0·7% PWP (45, 58, 71%, respectively). There was a synergistic effect of 0·3% β-CD and 0·6% PWP in decreasing the contents of SM-FFA (C6, C8, C10) sharply by 89, 90, 79%. Under the same percentage of addition, yogurts made with β-CD showed a higher (P < 0·05) apparent viscosity than those with PWP. However, the addition of PWP could increase the texture parameters of fermented goat milk (P < 0·05). Combination of PWP and β-CD presented a more desirable texture and consistency in fermented goat milk. Results indicated that polymerized whey protein can be used to reduce the goaty flavor and improve the texture of fermented goat milk.
We previously reported four heterozygous missense mutations of MYH7, KCNQ1, MYLK2, and TMEM70 in a single three-generation Chinese family with dual Long QT and hypertrophic cardiomyopathy phenotypes for the first time. However, the clinical course among the family members was various, and the potential myocardial dysfunction has not been investigated.
The objective of this study was to investigate the echocardiographic and electrocardiographic characteristics in a genetic positive Chinese family with hypertrophic cardiomyopathy and further to explore the association between myocardial dysfunction and electric activity, and the identified mutations.
A comprehensive echocardiogram – standard two-dimensional Doppler echocardiography and three-dimensional speckle tracking echocardiography – and electrocardiogram were obtained for members in this family.
As previously reported, four missense mutations – MYH7-H1717Q, KCNQ1-R190W, MYLK2-K324E, and TMEM70-I147T – were identified in this family. The MYH7-H1717Q mutation carriers had significantly increased left ventricular mass indices, elevated E/e’ ratio, deteriorated global longitudinal stain, but enhanced global circumferential and radial strain compared with those in non-mutation patients (all p<0.05). The KCNQ1-R190W carriers showed significantly prolonged QTc intervals, and the MYLK2-K324E mutation carriers showed inverted T-waves (both p<0.05). However, the TMEM70-I147T mutation carriers had similar echocardiography and electrocardiographic data as non-mutation patients.
Three of the identified four mutations had potential pathogenic effects in this family: MYH7-H1717Q was associated with increased left ventricular thickness, elevated left ventricular filling pressure, and altered myocardial deformation; KCNQ1-R190W and MYLK2-K324E mutations were correlated with electrocardiographic abnormalities reflected in long QT phenotype and inverted T-waves, respectively.
In this paper, the kinematic accuracy problem caused by geometric errors of a 2(3HUS+S) parallel manipulator is described. The kinematic equation of the manipulator is obtained by establishing a D–H (Denavit–Hartenberg) coordinate system. A D–H transformation matrix is used as the error-modeling tool, and the kinematic error model of the manipulator integrating manufacturing and assembly errors is established based on the perturbation theory. The iterative Levenberg–Marquardt algorithm is used to identify the geometric errors in the error model. According to the experimentally measured attitudes, the kinematic calibration process is simulated using MATLAB software. The simulation and experiment results show that the attitude errors of the moving platforms after calibration are reduced compared with before the calibration, and the kinematic accuracy of the manipulator is significantly improved. The correctness and effectiveness of the error model and the kinematic calibration method of the 2(3HUS+S) parallel manipulator for simulation of hip joint motion are verified.
Single-crystal-like TiO2 is claimed to be a very promising material among various catalysts. In this study, the (N,F)-co-doped single-crystal-like TiO2 was prepared by a new molten mixing process in which the mixed nitrates were used both as a morphology modifier and an N-doping agent at the same time. The prepared samples also had well-developed (001) facet due to the addition of HF. The HF can also be an F doping agent to the material. The co-doping of N and F can diminish the band gap of TiO2 from 3.05 to 2.93 eV, therefore visible light can be used effectively by the material. In addition, NO and fluorine ions existing on the surface of the sample can also help its photocatalyticity. Therefore, the photocatalytic performance of the as-prepared sample was effectively improved.
Nanotechnology has been considered as a promising strategy for diagnosis and treatment of various diseases. However, the stability and circulation times of the conventional nano-carriers, such as liposomes and micelles, are still unsatisfied. Perfluorocarbons (PFCs) are biologic inert synthetic materials, which are highly hydrophobic and have a tendency to self-aggregation. Additionally, PFCs themselves can act as 19F magnetic resonance imaging agents and oxygen carriers. Thus, the construction of the fluorinated carriers will not only improve the stability of the carriers, but also endow them with additional functions. Here we review the recent advances of PFC-based nanosystems for diagnosis and treatment of diseases.
For the first time, an experiment has been conducted to investigate synthetic jet laminar vortex rings impinging onto porous walls with different geometries by time-resolved particle image velocimetry. The geometry of the porous wall is changed by varying the hole diameter on the wall (from 1.0 mm to 3.0 mm) when surface porosity is kept constant (
). The finite-time Lyapunov exponent and phase-averaged vorticity field derived from particle image velocimetry data are presented to reveal the evolution of the vortical structures. A mechanism associated with vorticity cancellation is proposed to explain the formation of downstream transmitted vortex rings; and both the vortex ring trajectory and the time-mean flow feature are compared between different cases. It is found that the hole diameter significantly influences the evolution of the flow structures on both the upstream and downstream sides of the porous wall. In particular, for a porous wall with a small hole diameter (
, 0.10 and 0.133), the transmitted finger-type jets will reorganize into a well-formed transmitted vortex ring in the downstream flow. However, for the case of a large hole diameter of
, the transmitted vortex ring is not well formed because of insufficient vorticity cancellation. Additionally, the residual vorticity gradually evolves into discrete jet-like structures downstream, which further weaken the intensity of the transmitted vortex ring. Consequently, the transmitted flow structures for the
case would lose coherence more easily (or probably even transition to turbulence), resulting in a faster decay of the axial velocity and stronger entrainment of the transmitted jet. For all porous wall cases, the velocity profile of the transmitted jet exhibits self-similar behaviour in the far field (
), which agrees well with the velocity distribution of free synthetic jets. With the help of the control-volume approach, the time-mean drag of the porous wall is evaluated experimentally for the first time. It is shown that the porous wall drag increases with the decrease in the hole diameter. Moreover, for a porous wall with a small hole diameter (
, 0.10 and 0.133), it appears that the porous wall drag mainly derives from the viscous effect. However, as
increases to 0.20, the form drag associated with the porous wall geometry becomes significant.
Excited by the great success of metal halide perovskites in the optoelectronic and electro-optic fields and the interesting emerging physics (Rashba splitting, quantum anomalous hall effect) of layered metal halides, metal halides have recently been attracting significant attentions from both research and industrial communities. It is shown that most progresses have been made when these materials are obtained at reduced dimensions. Among several growth methods, vapor phase epitaxy has been demonstrated with a universal control on morphology, phase, and composition. We thus believe that a thorough understanding on the physical properties and on the growth of general metal halide compounds at reduced dimensions would be very beneficial in the study of recent perovskites and layered metal halide materials. This review covers the physical properties of most studied metal halides and summarizes the vapor phase epitaxial growth knowledge collected in the past century. We hope that this comprehensive review could be helpful in designing new physical properties and in planning growth parameters for emerging metal halide crystals.
We discuss an efficient preconditioner and iterative numerical method to solve large complex linear algebraic systems of the form (W + iT)u = c, where W and T are symmetric matrices, and at least one of them is nonsingular. When the real part W is dominantly stronger or weaker than the imaginary part T, we propose a block multiplicative (BM) preconditioner or its variant (VBM), respectively. The BM and VBM preconditioned iteration methods are shown to be parameter-free, in terms of eigenvalue distributions of the preconditioned matrix. Furthermore, when the relationship between W and T is obscure, we propose a new preconditioned BM method (PBM) to overcome this difficulty. Both convergent properties of these new iteration methods and spectral properties of the corresponding preconditioned matrices are discussed. The optimal value of iteration parameter for the PBM method is determined. Numerical experiments involving the Helmholtz equation and some other applications show the effectiveness and robustness of the proposed preconditioners and corresponding iterative methods.