Mechanical metamaterials are of tremendous research interest due to their unconventional properties that arise from unit microstructure. Shape‐reconfiguration is an effective method to realize ...programmability on various properties for different tasks of a structure or system, while existing researches focus on multiple degree‐of‐freedom (DOF) systems or limited configurations that morph along a single kinematic path. Here, starting from a one‐DOF Wohlhart polyhedron module, its interesting topological transformation is explored along multiple motion paths through kinematic bifurcations, accompanied by tunable mechanical properties, including Poisson's ratio, chirality, and stiffness. Furthermore, these modules are tessellated into 3D metamaterials to harness their reconfigurability to independently program the Poisson's ratios in orthogonal planes within a wide range of negative Poisson's ratio, positive Poisson's ratio, and even zero Poisson's ratio. This work opens up avenues for the design of programmable metamaterials based on the perspective of kinematic bifurcation generating from single DOF systems, which can readily be applied in shape‐morphing systems in various fields, such as flexible metamaterials, morphing architectures, and deployable structures.
A one‐degree‐of‐freedom reconfigurable module exhibits distinct topological transformation along multiple motion paths, accompanied by tunable mechanical properties, including Poisson's ratio, chirality, and stiffness. The modules are tessellated into 3D metamaterials to harness their reconfigurability to independently program the Poisson's ratios in orthogonal planes within a wide range of negative, positive, and even zero Poisson's ratios.
With the long-term mining activation and use of coal, ecological environment of mining area has been damaged to a certain extent. As one of the 13 large coal bases in China, Huainan coal mining area ...was selected to evaluate the ecosystem service value and ecological storage value. Remote sensing images of 2000, 2005, 2010 and 2015 based on Landsat series in Huainan mining area were employed to obtain the classification information of the surface. Referring to the existing research results, ecological service value was computed. By using a mining area ecological storage model, estimation of ecological storage were studied. Results showed that ecological service value and ecological storage both showed a downward trend. Finally, the paper put forward the comprehensive treatment countermeasures and remediation strategy of ecological environment.
This work presents a dynamics model of triboelectric nanogenerator (TENG) transducers, which connects the TENG structural mode and parameters, the motion input, the electrical signal output and the ...electrostatic force feedback. On this basis, a fast numerical method is proposed for the TENG performance prediction, and its numerical results are in good agreement with those of the finite element method (FEM). Furthermore, using this model, some important and interesting issues including the periodic input, the limiting output, and the similarity are discussed.
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•A dynamics model of TENGs is presented.•A periodic motion input leads to a periodic dynamic output.•A TENG has an upper electrical output limit independent of the input frequency and even of the TENG size.•Similarity exists in the phenomena in which TENGs move and generate electricity.
Flexible job-shop problem has been widely addressed in literature. Due to its complexity, it is still under consideration for research. This paper addresses flexible job-shop scheduling problem ...(FJSP) with three objectives to be minimized simultaneously: makespan, maximal machine workload, and total workload. Due to the discrete nature of the FJSP problem, conventional particle swarm optimization (PSO) fails to address this problem and therefore, a variant of PSO for discrete problems is presented. A hybrid discrete particle swarm optimization (DPSO) and simulated annealing (SA) algorithm is proposed to identify an approximation of the Pareto front for FJSP. In the proposed hybrid algorithm, DPSO is significant for global search and SA is used for local search. Furthermore, Pareto ranking and crowding distance method are incorporated to identify the fitness of particles in the proposed algorithm. The displacement of particles is redefined and a new strategy is presented to retain all non-dominated solutions during iterations. In the presented algorithm,
pbest
of particles are used to store the fixed number of non-dominated solutions instead of using an external archive. Experiments are performed to identify the performance of the proposed algorithm compared to some famous algorithms in literature. Two benchmark sets are presented to study the efficiency of the proposed algorithm. Computational results indicate that the proposed algorithm is significant in terms of the number and quality of non-dominated solutions compared to other algorithms in the literature.
Power option is such an option whose payoff is based on the price of the underlying asset raised to some power. Unlike Black–Scholes setting, we investigate the valuation of power options under the ...assumption that the underlying stock price is assumed to follow an uncertain differential equation, and derive the pricing formulas of power options for Liu’s uncertain stock model with the method of uncertain calculus based on uncertainty theory. Some numerical examples are given to illustrate the pricing formulas.
A traditional flat-panel spectrometer does not allow high-resolution observation and miniaturization simultaneously. In this study, a compact, high-resolution cross-dispersion spectrometer was ...designed based on the theoretical basis of echelle grating for recording an infrared spectrum. To meet the high-resolution observation and miniaturization design requirements, a reflective immersion grating was used as the primary spectroscopic device. To compress the beam aperture of the imaging system, the order-separation device of the spectrometer adopted toroidal uniform line grating, which had both imaging and dispersion functions in the spectrometer. The aberration balance condition of the toroidal uniform line grating was analyzed based on the optical path difference function of the concave grating, and dispersion characteristics of the immersed grating and thermal design of the infrared lens were discussed based on the echelle grating. An immersion echelle spectrometer optical system consisting of a culmination system, an immersed echelle grating, and a converged system was used. The spectrometer was based on the asymmetrical Czerny-Turner and Littrow mount designs, and it was equipped with a 320 × 256 pixel detector array. The designed wavelength range was 3.7–4.8 μm, the F-number was 4, and the central wavelength resolution was approximately 30,000. An infrared cooling detector was used. The design results showed that, in the operating band range, the root implied that the square diameter of the spectrometer spot diagram was less than 30 μm, the energy was concentrated in a pixel size range, and the spectrometer system design met the requirements.
ObjectivesThis study was to investigate the colonisation rate of Group B Streptococcus (GBS) during pregnancy, and to evaluate the influence of GBS colonisation on pregnancy outcomes.DesignA ...retrospective cohort study.SettingData of 47 380 pregnant women from 2016 to 2022 were collected from the Maternal and Child Health Hospital of Huadu District, Guangzhou City, China.ParticipantsA total of 15 040 pregnant women were eligible for this study, of which 32 340 were excluded due to non-native pregnant women, in vitro fertilization infants, malformed fetuses, habitual abortion, abortions due to poor reproductive or obstetrical history, artificial insemination, umbilical cord torsion, and other diseases during pregnancy.Primary outcome measuresThe incidence rates of GBS colonisation and premature delivery, fetal distress, premature rupture of membranes (PROM), low birth weight (LBW), abortion and stillbirth.ResultsOf the 15 040 pregnant women included in this study, 1445 developed GBS colonisation, with a prevalence of 9.61% (95% CI, 9.15 to 10.09). Advanced maternal age (≥35 years) predisposed women to GBS colonisation, and the occurrence of GBS colonisation varied among different ethnic groups. Our data revealed that fetal distress, PROM and LBW were more common in pregnant women colonised with GBS than in pregnant women not colonised with GBS. The incidence for premature delivery, fetal distress, PROM and LBW in infants of pregnant women colonised with GBS was 41.0% (OR=1.410, 95% CI, 1.134 to 1.753), 282.5% (OR=3.825, 95% CI, 3.185 to 4.593), 14.9% (OR=1.149, 95% CI, 1.005 to 1.313), and 29.7% (OR=1.297, 95% CI, 1.010 to 1.664), respectively.ConclusionsGBS colonisation was relatively low in pregnant women in Guangzhou. Women of advanced maternal age were more prone to GBS colonisation, and pregnant women colonised with GBS were more predisposed to fetal distress, PROM and LBW.
Aim
To explore the association between common pregnancy complications and low birth weight (LBW) neonates in preterm birth.
Methods
The study included 1764 pregnant women who experienced a single ...birth prematurely at a city hospital in Guangzhou, China between January 1, 2017 and December 31, 2019. A total of 874 normal birth weight neonates and 890 LBW neonates were included. Multivariate logistic regression analysis was conducted to identify and measure risk factors; two‐tailed test was applied, with a p ≤ 0.05 considered statistically significant.
Results
Hypertension was the primary risk factor of LBW in preterm neonates, odds ratio (OR) = 2.912 (p < 0.001; 95% confidence interval CI, 2.044–4.149), followed by hypothyroidism, OR = 1.807 (p = 0.046; 95% CI, 1.012–3.226), placental abruption, OR = 1.759 (p = 0.049; 95% CI, 1.002–3.087), reproductive tract infection, OR = 1.746 (p < 0.001; 95% CI, 1.325–2.301), abnormal amniotic fluid volume, OR = 1.737 (p = 0.003; 95% CI, 1.202–2.501), and fetal distress OR = 1.690 (p = 0.012; 95% CI, 1.120–2.551).
Conclusion
Preventing risk factors, such as hypertension, hypothyroidism, and reproductive tract infections, during pregnancy may reduce the incidence of LBW neonates.
Adipose derived stem cells (ADSCs) are popular in regenerative medicine due to their easy availability, low immunogenicity and lack of controversy regarding their ethical debate use. Although ADSCs ...can repair nerve damage, the oxidative microenvironment of damaged tissue can induce apoptosis of transplanted stem cells, which weakens the therapeutic efficacy of ADSCs. Resveratrol (Res) is a type of natural polyphenol compound that regulates the proliferation, senescence and differentiation of stem cells. Therefore, we investigated whether incubation of ADSCs with Res improves their to promote peripheral nerve regeneration. ADSCs were cultured in vitro and treated with H
O
to establish an apoptosis model. The control, H
O
and Res groups were set up. The cell survival rate was detected by the CCK-8 method. The TUNEL assay was used to detect the apoptosis of the cells. qRT‒PCR was used to analyze the expression of apoptosis-related mRNA, and the effect of Res on the proliferation of ADSCs was investigated. In vivo, 40 SD rats were randomly divided into the control, model, ADSCs and ADSC + Res groups, with 13 rats in each group. The sciatic nerve injury rat model was established by the clamp method. Gait was observed on Days 7, 14, 21, and 28. Sciatic nerve regeneration was detected on Day 28. Res had no effect on the proliferation of ADSCs, and the TUNEL assay confirmed that Res pretreatment could significantly improve H
O
-induced apoptosis in ADSCs. Compared with the control group, caspase-3, Bax and Bcl-2 expression levels were significantly increased in the H
O
group. Compared with the H
O
group caspase-3 and Bax expression levels were significantly decreased, and Bcl-2 expression levels were significantly increased in ADSCs + Res group. At 4 weeks after surgery, the functional index of the sciatic nerve in the ADSCs + Res group was significantly higher than that in the model group. On Day 28, the average density of the sciatic nerve myelin sheath in the ADSCs + Res group was significantly increased compared with that in the model group, and Nissl staining showed that the number of motor neurons in the spinal cord was significant compared with that in the model group. Compared with the control group, the wet weight ratio of gastrocnemius muscle and muscle fiber area in ADSCs + Res group were significantly increased. Res enhanced the ability of ADSCs to promote sciatic nerve regeneration in rats.
Mycoplasma gallisepticum (MG) can cause chronic respiratory disease (CRD) in chickens, which has a significant negative economic impact on the global poultry sector. Respiratory flora is the guardian ...of respiratory health, and its disorder is closely related to respiratory immunity and respiratory diseases. As a common probiotic in the chicken respiratory tract, Lactobacillus salivarius (L. salivarius) has potential antioxidant, growth performance enhancing, and anti-immunosuppressive properties. However, the specific mechanism through which L. salivarius protects against MG infection has not yet been thoroughly examined. This study intends to investigate whether L. salivarius could reduce MG-induced tracheal inflammation by modulating the respiratory microbiota and metabolites. The results indicated that L. salivarius reduced MG colonization significantly and alleviated the anomalous morphological changes by using the MG-infection model. L. salivarius also reduced the level of Th1 cell cytokines, increased the level of Th2 cell cytokines, and ameliorated immune imbalance during MG infection. In addition, L. salivarius improved the mucosal barrier, heightened immune function, and suppressed the Janus kinase/Signal transducer, and activator of transcription (JAK/STAT) signaling pathway. Notably, MG infection changed the composition of the respiratory microbiota and metabolites, and L. salivarius therapy partially reversed the aberrant respiratory microbiota and metabolite composition. Our results highlighted that these findings demonstrated that L. salivarius played a role in MG-mediated inflammatory damage and demonstrated that L. salivarius, by altering the respiratory microbiota and metabolites, could successfully prevent MG-induced inflammatory injury in chicken trachea.
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