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A weak circumferential resolution of defects in the corner part of engineering components brings great challenges to quantitative non-destructive testing. Especially for the corner of carbon fiber reinforced plastics (CFRP), the complex wave propagation behaviors caused by the elastic anisotropy, laminate structure, and curved surface make the information of defects hard to be distinguished, which finally results in a poor imaging resolution. The surface adaptive ultrasonic (SAUL) method for CFRP corner is investigated, and an improved strategy, focusing in receiving (FiR) of SAUL signals is proposed here. With an isotropic plexiglass as a comparison, the effectiveness of FiR is verified by finite element simulations and experiments. The elastic properties of CFRP corner are accurately characterized and a finite element model is established. On this basis, the wave propagation behavior in the corner is studied, and the influence of the water distance h on the maximum amplitude (MAD) and signal-to-noise ratio (SNR) at the defect is analyzed. The results show that the structural noise can be eliminated, and the imaging quality and SNR can be improved by optimizing the h. After FiR, the maximum increase of defect amplitude is about 9.5 dB and 13.2 dB for plexiglass and CFRP, respectively. Meanwhile, the maximum relative error in length is reduced by 16.7% in plexiglass, and by 13.4% for the 3-mm delamination in CFRP. The strategy would be promising to improve the detection quality of the corner in curved components. [ABSTRACT FROM AUTHOR]

• This paper presents a solution methodology for the rotor system with bolted joint. • The presented solution methodology is verified by the Newmark method. • The 3X and 5X of the rotating frequency are found in the spectrum. • The rotating speed corresponding to 5X's peak precedes the critical speed. • The findings of spectral characteristics are verfied by the experimental test. The bolted joint is commonly used to connect several parts of aero-engine rotor system. Several papers have studied the nonlinear vibration responses of bolted rotor systems. However, the frequency spectrum characteristics of bolted rotor systems are not fully revealed. Aiming at this issue, this study develops a dynamic model of the bolted rotor system, where the piecewise stiffness characteristic is considered. A solution methodology is presented by incorporating the piecewise stiffness into the incremental harmonic balance method. The effects of unbalance and preload on the dynamic characteristics are discussed. Moreover, the stiffness and damping of the support structure and bolted joint are identified based on the particle swarm optimization algorithm and experimental results. Furthermore, the experimental study on a bolted rotor test rig is conducted to verify the accuracy of the identified parameters and the model. The simulation and experimental results indicate that 3X and 5X of the rotating frequency can be observed. Besides, the rotating speed corresponding to 5X's peak is different from the critical speed, and the peak of 5X precedes the primary resonance peak. [ABSTRACT FROM AUTHOR]

The similitude theory helps to understand the physical behaviors of large structures through scaled models. Several papers have studied the similitude of shock issues. However, the dynamic similitude for shock responses of coupled structures is rarely incorporated in open studies. In this paper, scaling laws are derived for the shock responses and spectra of coupled structures. In the presented scaling laws, the geometric distortion and energy loss are considered. The ability of the proposed scaling laws is demonstrated in the simulation and experimental cases. In both cases, the similitude prediction for the prototype's time-domain waveform and spectrum is conducted with the scaled model and scaling laws. The simulation and experimental cases indicate that the predicted shock responses and spectra agree well with those of the prototype, which verifies the proposed scaling laws for predicting shock responses. [ABSTRACT FROM AUTHOR]

The support structure of a rotor system is subject to vibration excitation, which results in the stiffness of the support structure varying with the excitation frequency (i.e., the dynamic stiffness). However, the dynamic stiffness and its effect mechanism have been rarely incorporated in open studies of the rotor system. Therefore, this study theoretically reveals the effect mechanism of dynamic stiffness on the rotor system. Then, the numerical study and experimental verification are conducted on the dynamic stiffness characteristics of a squirrel cage, which is a common support structure for aero-engine. Moreover, the static stiffness experiment is also performed for comparison. Finally, a rotor system model considering the dynamic stiffness of the support structure is presented. The presented rotor model is used to validate the results of the theoretical analysis. The results illustrate that the dynamic stiffness reduces the critical speed of the rotor system and may lead to a new resonance. [ABSTRACT FROM AUTHOR]

Similitude laws can be used to extrapolate the vibration characteristic of a small, inexpensive, and easily tested model into structural behavior for the full-size prototype. In this article, a systematic similitude approach is proposed to predict the natural frequency, mode shape, and vibration response of composite laminated plates. The emphasis of this article is to predict the vibration characteristic of composite laminated plates in an effective and convenient way. Sensitivity analysis (SA) is introduced to improve the prediction accuracy of natural frequency. For distortion similarity, the prediction accuracy is improved close to 5%. Modal assurance criterion (MAC) measures the consistency of mode shapes of the full-size prototype and scaled models. The influence of stacking sequence on mode consistency is investigated. Similitude based on virtual mode and statistical energy (SVMSE) is proposed to extrapolate the transient response of the prototype to simulate the shock environment, such as satellite–rocket separation, etc. In conclusion, the prediction accuracy of natural frequency, mode consistency, and response coincidence are considered comprehensively to extrapolate the vibration characteristic of the full-size laminated plates. [ABSTRACT FROM AUTHOR]

Simple Summary: Cancer remains a serious health problem owing to its high morbidity and mortality. Immunotherapy, represented by anti-programmed death-1D1/anti-PD-Ligand 1 treatments, has become one of the most important methods for cancer treatment. However, there are still some challenges in this method such as low response rate, limited therapeutic targets, and unclear underlying molecular mechanisms of immune checkpoints. Thus, in this review, we aim to focus on the proliferative role of fifteen immune checkpoints that occur in various tumors. This has provided more clarity on the functions and mechanisms of immune checkpoints in tumors, especially on their proliferation role. This may provide better insights in developing more therapeutic targets and strategies in tumor immunotherapy. Cancer remains a serious social health problem, and immunotherapy has become the major treatments in tumor treatment. Additionally, improving the efficiency and safety of treatment is necessary. Further, more therapy targets are warranted for future tumor treatments. In this review, in addition to examining the currently recognized role of immune regulation, we focus on the proliferative role of 15 immune checkpoints in various tumors, including PD1, PD-L1, FGL1, CD155, CD47, SIRPα, CD276, IDO1, SIGLEC-15, TIM3, Galectin-9, CD70, CD27, 4-1BBL, and HVEM. We managed to conclude that various immune checkpoints such as PD1/PD-L1, FGL1, CD155, CD47/SIRPα, CD276, and SIGLEC-15 all regulate the cell cycle, and specifically through Cyclin D1 regulation. Furthermore, a variety of signal pathways engage in proliferation regulation, such as P13K, AKT, mTOR, and NK-κB, which are also the most common pathways involved in the regulation of immune checkpoint proliferation. Currently, only PD1/PD-L1, CD47/SIRPα, TIM3/Galectin-9, and CD70/CD27 checkpoints have been shown to interact with each other to regulate tumor proliferation in pairs. However, for other immune checkpoints, the role of their receptors or ligands in tumor proliferation regulation is still unknown, and we consider the enormous potential in this area. An increasing number of studies have validated the various role of immune checkpoints in tumors, and based on this literature review, we found that most of the immune checkpoints play a dual regulatory role in immunity and proliferation. Therefore, the related pathways in proliferation regulation can served the role of therapy targets in tumor therapy. Further, great potential is displayed by IDO1, SIGLEC-15, 4-1BBL, and HVEM in tumor proliferation regulation, which may become novel therapy targets in tumor treatment. [ABSTRACT FROM AUTHOR]

Elastic ring squeeze film damper (ERSFD) is extensively used in industrial rotating systems due to its excellent noise control and vibration suppression characteristics. However, the oil film sealing and leakage has a profound effect on the mechanical and vibration characteristics of the ERSFD and the ERSFD-rotor during operation. The sealing and leakage reduce the axial flow of the oil film, leading to changes in the initial boundary conditions of the flow field, which in turn affects the oil film pressure and damping coefficient of ERSFD. Meanwhile, the sealing causes an increase in the oil film force of ERSFD, which in turn affects the response of the rotor system. But there is relatively little research on the impact of sealing and leakage on the dynamic performances of ERSFD-rotor. In this paper, a mathematical model of ERSFD under different sealing conditions (no end seal, complete end seal, piston ring seal, O-ring seal) is established by changing the initial boundary equations of the flow field of ERSFD and the coupled solution of the Reynolds equation of ERSFD with different sealing and leakage boundary equations is realized. Then, the characteristics of oil film pressure and force of ERSFD under different sealing conditions is studied. After that, an ERSFD-rotor model considering oil film sealing and leakage is established based on displacement compatibility conditions and force balance principles. Meanwhile, the impact of sealing and leakage on the amplitude-frequency relation and sudden imbalance of an ERSFD combined support rotor is researched. The research results reveal that good sealing can significantly increase the damping of the system, thereby reducing the vibration amplitude of the ERSFD-rotor system. In addition, good sealing conditions can also shorten the transient process of sudden unbalanced excitation. Finally, the effectiveness of some simulation results was verified through experiments on the ERSFD rotor test bench. • This paper proposes a model of ERSFD under different sealing conditions by coupling different boundary equations. • The dynamic characteristics of oil film pressure and force of ERSFD under different sealing conditions are analyzed. • The impact of different sealing and leakage conditions on vibration amplitude and damping of ERSFD rotor is analyzed. • Experimental testing for the amplitude frequency response of ERSFD-rotor with no end seal is carried out. [ABSTRACT FROM AUTHOR]

In actual engineering practice of the variable stator vane (VSV) adjustment mechanism, it has been found that the deformation beyond design conditions of the kinematic chain formed from the linkage ring to the blades influences the motion accuracy of the mechanism the most. In this paper, the static stiffness model of the components system, formed from the linkage ring to the blades, is developed and then a motion compensation method based on the stiffness model is proposed. The correctness of the stiffness model is verified by the FEA method. With the model, influence factors such as blade quantity on the stiffness are characterized. In order to investigate the engineering applicability of the stiffness model, the motion compensation model is applied to the dynamic analysis and contrasts with the experimental results of two test benches designed based on the real VSV mechanisms. As a result, the validity of the stiffness model and the value of the proposed method are both well affirmed. • Deformable components are extracted to form the components system. • The components system stiffness is theoretically evaluated. • The concept of motion compensation based on the stiffness model is proposed. • The stiffness model is applied to the dynamic analysis of test rigs. • The proposed model is recognized through experiments. [ABSTRACT FROM AUTHOR]

The supporting structure's dynamic stiffness has an important influence on the rotor system. However, current research is mainly limited to the stiffness of a single supporting structure. A single supporting structure may not meet the requirements of the rotor system in some cases. Therefore, the method of solving dynamic stiffness of combined supporting structure is presented and compared with the traditional method based on the parallel stiffness formula. The correctness of the proposed method is verified experimentally. Then, the model of rotor system is established that takes into account the combined supporting structure's dynamic stiffness. Finally, the variation of rotor system's critical speeds and vibration response under the influence of dynamic stiffness is analyzed. An experiment is carried out to verify the influence of dynamic stiffness on the critical speeds. Furthermore, the critical speeds of rotor system will decrease under the influence of dynamic stiffness. • This paper presents a dynamic stiffness model of the combined supporting structure. • The accuracy of the proposed model is validated by experiment. • The rotor system model considering dynamic stiffness is established. • The effect of dynamic stiffness on the rotor system is verified by numerical and experimental studies. [ABSTRACT FROM AUTHOR]

The purpose of this article is to study the coupling effects of support stiffness on geometric scaling factor powers of the rotor-bearing system and predict vibration characteristics of a prototype by scaled models accurately. Associated to the least-squares–based similitude method, the discrete iteration method proposed evaluates the estimated scaling laws under variable (instable) powers and further broadens the restriction of boundary conditions in scaling laws, which is the main finding in this article. The discrete iteration method does not need to establish a physical model but directly uses input and output parameters to establish output scaling laws. The complete scaled model and geometric distorted model are selected as study cases to prove the effectiveness and accuracy of the discrete iteration method. The vibration characteristics of the rotor-bearing system are obtained by the finite element method with validation by experimental test for the natural characteristics. The comparison between the prediction results and those without the discrete iteration method shows that discrete iteration method can significantly improve the accuracy for predicting the prototype. [ABSTRACT FROM AUTHOR]

The boundary element method- (BEM-) based free field recovery technique (FFRT) has been proposed to recover the free field radiated by an arbitrarily shaped source from the mixed field that would be measured in a noisy environment. However, that technique requires that the boundary integral equation should be established on an enclosed hologram surface surrounding the source, which means that the hologram surface should be discretized into elements and the measurement points should be located on the nodes of the elements. For large-scale or mid-high frequency problems, it makes the total number of measurement points huge since it should obey the criterion of more than six elements per wavelength, which put forward very high requirements for holographic data measurement. To overcome this problem, a more flexible BEM-based FFRT without the restriction on the locations of measurement points is proposed in this study. In virtue of this, a three-dimensional scanning measurement method can be applied to acquire holographic data with high efficiency. The effectiveness of the proposed method is validated by two numerical simulations and an experiment. [ABSTRACT FROM AUTHOR]

This article presents a novel system identification method for the dynamic parametrical model of the rotor-bearing system based on the Nonlinear Auto-Regressive with exogenous inputs (NARX) model, where the physical parameter of the system appears as coefficients in the model. Customarily, the NARX model-based modeling techniques require random signals as input, which leads to the rotor-bearing system that cannot be modeled using such techniques. To solve this issue, an improved system identification method, defined as the frequency sweep system identification approach is proposed in this paper. Firstly, the frequency domain version modeling framework with a physical parameter is derived based on the traditional modeling framework of the dynamic parametrical model. And then, the candidate model term dictionary corresponding to the frequency domain version modeling framework is derived. The Predicted Residual Sums of Squares based Extended Forward Orthogonal Regression algorithm is applied to identify the dynamic parametrical model of the rotor system. The model obtained by using the proposed method is validated based on the Model Predicted Output method. Finally, an experimental case of the rotor-bearing test rig is demonstrated to show the feasibility of the proposed method for real-world scenarios. Both the numerical and experimental studies illustrating the feasibility of the proposed modeling method, which provides a reliable model for time-domain response prediction and dynamic analysis of the rotor system. [ABSTRACT FROM AUTHOR]

In rotating machines, bolted joints are widely employed to connect adjacent disks to make multiple parts into an integrated one. The contact interface, subjected to tangential force introduced by unbalanced forces during normal operation, influencing the rotor dynamics, especially in the presence of relative speed, is of interest for investigations. However, there are little researches on the rotor dynamics considering the contact interface friction of the bolted disk joint. Thus, a dynamic model of the rotor-bearing system is established, which considers the friction at the contact interface between disks, nonlinear oil-film force, etc. The nonlinear dynamic phenomena of the rotor system were investigated using the fourth-order Runge–Kutta method. Bifurcation diagrams, vibration waveforms, frequency spectrums, shaft orbits, and Poincaré maps are used to demonstrate the diversity of the system responses. The results indicate that the rotor system exhibits a rich diversity motion states, such as periodic-1 motion, multiple periodic motion, and quasi-periodic motion. The parametric study about the effect of friction coefficient on rotor dynamics is also conducted in the present work, which shows that a larger friction coefficient will lead the system enters into an unstable motion state at high rotating speed, and make the system enters into multiple periodic bifurcations at a higher rotating speed. The corresponding results can contribute to the further understanding of the nonlinear dynamic characteristics of the bolted joint rotor-bearing system. [ABSTRACT FROM AUTHOR]

Background: As the birth policy has been adjusted from one-child-one-couple to universal two-child-one-couple in China, there is an increasing number of women undergoing a second pregnancy after a previous cesarean section (CS). Undertaking an elective repeat CS (ERCS) has been taken for granted and has thus become a major contributor to the increasing CS rate in China. Promoting trial of labor after CS (TOLAC) can reduce the CS rate without compromising delivery outcomes. This study aimed to investigate Chinese obstetricians' perspectives regarding TOLAC, and the factors associated with their decision-making regarding recommending TOLAC to pregnant women with a history of CS under the two-child policy.Methods: A cross-sectional survey was carried out between May and July 2018. Binary logistic regression was used to determine the factors associated with the obstetricians' intention to recommend TOLAC to pregnant women with a history of CS. The independent variables included sociodemographic factors and perceptions regarding TOLAC (selection criteria for TOLAC, basis underlying the selection criteria for TOLAC, and perceived challenges regarding promoting TOLAC).Results: A total of 426 obstetricians were surveyed, with a response rate of ≥83%. The results showed that 31.0% of the obstetricians had no intention to recommend TOLAC to pregnant women with a history of CS. Their decisions were associated with the perceived lack of confidence regarding undergoing TOLAC among pregnant women with a history of CS and their families (odds ratio [OR] = 2.31; 95% CI: 1.38-1.38); obstetricians' uncertainty about the safety of TOLAC for pregnant women with a history of CS (OR = 0.49; 95% CI: 0.27-0.96), and worries about medical lawsuits due to adverse delivery outcomes (OR = 0.14; 95% CI: 0.07-0.31). The main reported challenges regarding performing TOLAC were lack of clear guidelines for predicting or avoiding the risks associated with TOLAC (83.4%), obstetricians' uncertainty about the safety of TOLAC for women with a history of CS (81.2%), pregnant women's unwillingness to accept the risks associated with TOLAC (81.0%) or demand for ERCS (80.7%), and the perceived lack of confidence (77.5%) or understanding (69.7%) regarding undergoing TOLAC among pregnant women and their families.Conclusion: A proportion of Chinese obstetricians did not intend to recommend TOLAC to pregnant women with a history of CS. This phenomenon was closely associated with obstetricians' concerns about TOLAC safety and perceived attitudes of the pregnant women and their families regarding TOLAC. Effective measures are needed to help obstetricians predict and reduce the risks associated with TOLAC, clearly specify the indications for TOLAC, improve labor management, and popularize TOLAC in China. Additionally, public health education on TOLAC is necessary to improve the understanding of TOLAC among pregnant women with a history of CS and their families, and to improve their interactions with their obstetricians regarding shared decision making. [ABSTRACT FROM AUTHOR]

For the characterization of joint contact model of the variable stator vane (VSV) mechanism, the dry friction properties of joint materials must be taken into account. In this paper, the important parameters characterizing the joint contact model are experimentally tested, and then the characterized contact model containing the parameters is utilized for the dynamic analysis of a principle-level VSV mechanism test rig, including the dry friction rotary pair. Firstly, the friction tests and the vibration tests induced by the friction process are carried out. Then an ideal comprehensive dynamic model of the scaled system of VSV mechanism's single kinematic chain is established through the Lagrange multiplier method. The friction coefficient values obtained from the test are embedded into the contact force model considering friction factors and compared with other macro models. The accuracy of the hybrid contact model is verified through a one-shot contact-impact simulation and the corresponding displacement is measured for evaluation with accuracy of established ideal dynamic model. Finally, the influence of different driving methods on the dynamic characteristics of the system is analyzed. • Characterization of joint contact model considering friction based on experiment. • Dynamic model of scaled VSV mechanism is established. • Application joint contact model to dynamic analysis of scale mechanism. [ABSTRACT FROM AUTHOR]

Background: The COVID-19 pandemic has caused more than 462,417 deaths worldwide. A large number of patients with severe COVID-19 face death in hospital. Hospice care is truly a philosophy of care that delivers patient-centred care to the terminally ill and their families. Hospice care could provide many benefits for patients, families, and for hospice caregivers. The aim of this study is to investigate hospice care self-efficacy and identify its predictors among Chinese clinical medical staff in COVID-19 isolation wards of designated hospitals. Methods: A cross-sectional design was used. The Hospice Care Self-Efficacy, Self-Competence in Death Work Scale, Positive Aspects of Caregiving, and Simplified Coping Style Questionnaires were administered between February and April 2020. A total of 281 eligible medical staff responded to the questionnaires, with a response rate of ≥78.9%. Results: The mean score of hospice care self-efficacy was 47.04 (SD = 7.72). Self-efficacy was predicted by self-competence in death work (B = 0.433, P < 0.001), positive aspects of caregiving (B = 0.149, P = 0.027), positive coping (B = 0.219, P < 0.001), giving hospice care to dying or dead patients before fighting against COVID-19 (B = -1.487, P = 0.023), occupational exposure while fighting against COVID-19 (B = -5.244, P = 0.004), holding respect for life and professional sentiment as motivation in fighting against COVID-19 (B = 2.372, P = 0.031), and grade of hospital employment (B = -1.426, P = 0.024). The variables co-explained 58.7% variation of hospice care self-efficacy. Conclusion: Clinical nurses and physicians fighting COVID-19 reported a moderate level of hospice care self-efficacy during this pandemic. Exploring the traditional Chinese philosophy of life to learn from its strengths and make up for its weaknesses and applying it to hospice care may provide a new framework for facing death and dying during the COVID-19 pandemic. Continuous hospice care education to improve self-competence in death work, taking effective measures to mobilize positive psychological resources, and providing safer practice environments to avoid occupational exposure are also essential for the improvement of the hospice care self-efficacy of clinical nurses and physicians. These measures help caregivers deal effectively with death and dying while fighting against the COVID-19 pandemic. [ABSTRACT FROM AUTHOR]

The finite size of a sound-absorbing material may lead to inaccurate results when measuring the acoustical properties of the material using the free-field measurement methods. In this study, a method of estimating the acoustical properties of locally reactive finite materials is proposed by combining a sound field model established by the boundary element method with an iteration algorithm. The proposed method takes the finiteness of the material into account, meaning that the size effect is removed and accurate results can be obtained. Numerical simulations and experiments of two kinds of materials, including a rigid floor and a porous material, are carried out to verify the validity of the proposed method. Results demonstrate that the proposed method is effective in estimating the acoustical properties of these two kinds of materials. Besides, a detailed analysis of the influences of the sample size, the source location, and the receiving point position is done in the simulations. [ABSTRACT FROM AUTHOR]

A dynamic model of the rotor-bearing system with bolted joint structure is set up based on the Lagrange's equations, which considers the bearing clearance, the gyroscopic effect and the initial deformation due to the non-uniform preload. The nonlinear dynamic responses of the system were obtained by using the Runge–Kutta–Fehlberg method, and then the influence of the radial bearing clearance on the nonlinear dynamic behaviors of the rotor system is studied by means of bifurcation diagram, frequency spectrum, shaft orbits and Poincaré maps. The results indicate that the larger bearing clearance will make the system enter into chaotic motion at a lower rotating speed. In addition, with the increase in bearing clearance, the duration of the chaotic motion becomes longer. Furthermore, the influence of initial deformation on the stability of the bolted joint rotor system with bearing clearance is studied. The results show that when the bearing clearance is present, the instability speed of the rotor system will gradually rise with the increase in initial deformation. Meanwhile, as the bearing clearance continuously increases, the regions of the chaotic motion become less and smaller, and the motion state should be completely changed under certain initial deformation. The related results can provide guidance for the optimization and design of the bolted joint rotor-bearing system. [ABSTRACT FROM AUTHOR]

C26H31N5NiO8, monoclinic, P21/n (no. 14), a = 12.554(3) Å, b = 12.401(3) Å, c = 18.718(5) Å, β = 107.844(3)°, V = 2774.0(12) Å3, Z = 4, Rgt(F) = 0.0438, wRref(F2) = 0.1175, T = 153(2) K. [ABSTRACT FROM AUTHOR]

The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km2. So far, sedimentary and geochemical characterizations have rarely been conducted on the shale in shallow (< 1000 m) areas in the southeastern part of the basin, but such characterizations can help identify the genesis of organic-rich shale and promote the prediction and recovery of shale oil. In this paper, several outcrop sections of the Chang 7 Member in the Tongchuan area were observed and sampled, and sedimentary and geochemical characterizations were conducted for the well-outcropped YSC section. The study results show that the Chang 7 Member shale is widely distributed laterally with variable thickness. The organic-rich shale is 7–25 m thick in total and exhibits obvious horizontal variation in mineral composition. In the eastern sections, the shale contains organic matter of Type II2–III and is low in thermal maturity, with high clay mineral content, low K-feldspar content, and no pyrite. In the western sections, the shale contains Type II1 organic matter and is low in thermal maturity, with high clay mineral, K-feldspar, and pyrite contents. The YSC section reveals three obvious intervals in vertical mineral composition and organic abundance. The Chang 7 Member organic-rich shale (TOC > 10%) contains mainly sapropelite and liptinite, with Type II kerogen. It is generally characterized by a hydrocarbon potential of more than 70 mg/g, low maturity, and shallow–semideep lacustrine facies. In the western sections, the shale, still in a low maturity stage, has a higher hydrocarbon potential and is optional for shale oil recovery. However, the Chang 7 Member shale in the study area is highly heterogeneous and its shale oil recovery is practical only in the organic-rich intervals. [ABSTRACT FROM AUTHOR]

Highlights • A kind of dynamic parametrical model is identified for the analysis and design on nonlinear systems. • An improved Extended Forward Orthogonal Regression algorithm is proposed to promote the efficiency in computation. • The proposed algorithm can circumvent the overfitting problem. • An iterative design that produces a sequence of suboptimal models is applied in the modeling process. Abstract In this study, the identification of a Nonlinear Auto-Regressive with exogenous inputs (NARX) model of nonlinear systems, where the physical parameters of interest for the system design appear explicitly as coefficients in the model, is studied. The model is a dynamic parametrical model, referred as the NARX model with parameters of interest for design (NARX-M-for-D). An improved algorithm, known as the Iterative Extended Forward Orthogonal Regression (IEFOR), is proposed to identify the NARX-M-for-D of nonlinear systems. Firstly, a common-structured model, referred to as the “initial model”, is established through the traditional Extended Forward Orthogonal Regression (EFOR) algorithm. Then an iterative process is applied to revise the initial model such to produce an improved model of the system, which is referred to as the “common model” in this study. Finally, functional relationships of the common model coefficients are established to determine the NARX-M-for-D of the system. Both the simulation and experimental studies are discussed to illustrate the application of the new algorithm. The results indicate that, by using the IEFOR algorithm, the established model can accurately predict the system out response and remain the merit of efficiency in computation. The new algorithm is expected to be applied in the identification of nonlinear systems in engineering practice. [ABSTRACT FROM AUTHOR]

The aim of the present study was to improve the conventional wire-guided localization biopsy (WGLB) of breast microcalcifications to overcome disadvantages associated with the procedure, including inaccurate localization and large specimen volume. The novel approach described in the present study was termed double wire-guided localization and rotary cutting biopsy (DWGLB). Prior to surgery, the precise localization of the lesions was assessed using two wires under the assistance of mammography X-ray and ultrasound, followed by complete excision of the lesions using a novel rotary cutting tool. The cylindrical specimen was placed on a scaled specimen holder for pathological examination. DWGLB was performed in 108 patients with the classification of as Breast Imaging Reporting and Data System score 4A. Percutaneous localization of the lesions guided by a mammography X-ray and ultrasound were successful in all 108 lesions (100%) with one puncture attempt. The lesions were precisely excised in all of 108 patients, and included 13 malignant lesions (DCIS of breast in 7 cases, DCIS with focal invasive carcinoma in 3 cases and invasive ductal carcinoma in 3 cases). The average distance of the BARD Dualok to the lesion was 4.1 mm; the average weight of specimens was 8.5 g. Compared with WGLB, DWGLB offers several advantages, including more accurate localization of lesions, a more standardized biopsy method and a smaller specimen volume. DWGLB can also provide the precise position of lesions in the specimen for further pathological examination. [ABSTRACT FROM AUTHOR]

To better suppress low-frequency vibrations of flexible manipulators induced by the rotation of motors and eccentricity, a novel type of tuned particle damper (TPD) is designed by combining the advantages of classical dynamic vibration absorber (DVA) and particle dampers (PD). Compared to traditional DVAs, this TPD can reduce additional mass and effectively broaden the frequency band of the DVA. Firstly, an equivalent theoretical model is established to describe the frequency tuning principle of the designed TPD. Based on the theory of a single particle damper, the equivalent damping and stiffness of the particles are calculated through an approximate approach. Then, a three-degree-of-freedom vibration model of the manipulator system with the TPD is built, and the dynamical characteristic of the primary resonance for the coupled system are analyzed by the perturbation method. Finally, the experimental platform is set up to verify the theoretical results. A manipulator is applied to test the low-frequency vibration absorption of the designed TPD, and the vibration suppression effect is discussed both in theoretical analysis and experiments. [ABSTRACT FROM AUTHOR]

This research proposes a novel type of variable stiffness tuned particle damper (TPD) for reducing vibrations in boring bars. The TPD integrates the developments of particle damping and dynamical vibration absorber, whose frequency tuning principle is established through an equivalent theoretical model. Based on the multiphase flow theory of gas-solid, it is effective to obtain the equivalent damping and stiffness of the particle damping. The dynamic equations of the coupled system, consisting of a boring bar with the TPD, are built by Hamilton's principle. The vibration suppression of the TPD is assessed by calculating the amplitude responses of the boring bar both with and without the TPD by the Newmark-beta algorithm. Moreover, an improvement is proposed to the existing gas-solid flow theory, and a comparative analysis of introducing the stiffness term on the damping effect is presented. The parameters of the TPD are optimized by the genetic algorithm, and the results indicate that the optimized TPD effectively reduces the peak response of the boring bar system. [ABSTRACT FROM AUTHOR]

C26H27ClN8NiO7, triclinic, P1̄ (no. 2), a = 9.893(2) Å, b = 11.503(2) Å, c = 13.295(3) Å, α = 78.77(3)°, β = 70.52(3)°, γ = 83.40(3)°, V = 1397.0(6) Å3, Z = 2, Rgt(F) = 0.0423, wRref(F2) = 0.1032, T = 153.15 K. [ABSTRACT FROM AUTHOR]

In recent decades, studies have reported that inflammation serves key roles in epilepsy and that high mobility group box protein-1 (HMGB1) may be involved in status epilepticus. However, it has not been reported whether HMGB1 participates in the pathogenesis of status epilepticus through the regulation of the p38 mitogen-activated protein kinase (p38MAPK) signalling pathway. In the present study, Sprague-Dawley rats were randomly divided into four groups as follows: Control, status epilepticus (SE), dimethyl sulfoxide treatment (DMSO + SE), and glycyrrhizin treatment (GL + SE) groups. Behavioural changes were then evaluated using the Racine score. In the hippocampus, the protein expression levels of HMGB1 were assessed using western blotting, the neuronal damage was evaluated using haematoxylin and eosin staining and transmission electron microscopy, and the activation of microglia was assessed using immunochemistry and immunofluorescence. The results demonstrated that, in the hippocampal region, HMGB1 existed in neurons and astrocytes and the protein expression levels of HMGB1, p38MAPK and phosphorylated-p38MAPK were significantly inhibited after treatment with GL. Furthermore, GL could alleviate neuronal injury in the CA1 region of the hippocampus and prevented HMGB1 translocation from the nucleus into the cytoplasm in these areas. These findings expand the understanding of how HMGB1 may participate in SE and lay a foundation for evaluation of HMGB1 as a drug target. [ABSTRACT FROM AUTHOR]

The Variable Stator Vane (VSV) mechanism is utilized to adjust the stator vane angles so as to delay the compressor stall. Establishing the dynamic model of the system, which is the basis to obtain different joint characteristics more in line with the real case, is worth analyzing. In this work, a comprehensive dynamic model of the scaled system of VSV mechanism's single kinematic chain by the Lagrange multiplier method is built, thus the spatial plane joint characteristic's effects on the behavior of the scaled system are investigated. Since a full-scale facility is unavailable for testing sometimes, the technique of similarity scaling is resorted to establishing the scaled principle-level model which has a certain relationship with the prototype in structure and material and so on. Then an example of the dynamic modeling procedure of the spatial RSSR mechanism included in the scaled model is presented with the aim of establishing a guide to model the whole system. Therefore, the equation of motion of the scale system is expediently established using some systematic method. Finally, inertial navigation sensors are used to measure the corresponding displacement for evaluation with accuracy of the established dynamic model. • Principle-level test rig design based on so-called similitude theory. • Dynamic model of scaled VSV mechanism is established. • The conformal contact model is applied, closer to the actual contact situation. • The rotation angle is measured using the inertial navigation system. • The rotation matrix of the rigid body based on the rotation axis vector is explained. [ABSTRACT FROM AUTHOR]

We study the destruction of heavy quarkonium due to the entropic force in a deformed AdS5 model. The effects of the deformation parameter on the interdistance and the entropic force are investigated. The influence of the deformation parameter on the quarkonium dissociation is analyzed. It is shown that the interdistance increases in the presence of the deformation parameter. In addition, the deformation parameter has the effect of decreasing the entropic force. These results imply that the quarkonium dissociates harder in a deformed AdS background than in a usual AdS background, in agreement with earlier findings. [ABSTRACT FROM AUTHOR]

Angular contact ball bearings are common basic components in rotating machinery. During the operation of the bearing, the rolling slips, resulting in contact sliding friction between it and the raceway, which in turn causes wear in the rolling element and increase in the radial clearance of the bearing. The increase in clearance also affects the stiffness of the bearing, which in turn affects the natural frequency and fatigue life of the bearing. At present, there are few studies on the influence of bearing wear (variation of clearance) on life. In this paper, the finite element model based on the theory of contact mechanics is established for the angular contact ball bearing with medium- and high-speed rotation, and the mechanical properties and fatigue life influenced by the internal action of the bearing are analyzed. The effects of radial load and deflection angle on the mechanical properties and fatigue life of the bearing are also studied. Based on the analysis results of bearing contact mechanical properties and clearance changes, the calculation method of bearing life under rolling element wear is established. The influence of the variation of clearance and preload clearance on bearing life is analyzed, and the optimal preload is obtained. The research results of this paper can provide a theoretical basis for optimizing the installation of angular contact ball bearings, reasonably determining the service conditions, and prolonging the service life of bearings, which is necessary for engineering practice. [ABSTRACT FROM AUTHOR]

Background: The optimal mode of delivery in twin pregnancies remains controversial. A recent randomized trial did not find any benefit of planned cesarean vs. vaginal delivery at 32–38 weeks gestation, but the trial was not powered to detect a moderate effect. We aimed to evaluate the impact of cesarean delivery on perinatal mortality and severe neonatal morbidity in twin pregnancies at ≥32 weeks through a large database exploration approach with the power to detect moderate risk differences. Methods: In a retrospective birth cohort study using the U.S. matched multiple births, 1995–2000 (the available largest multiple birth dataset), we compared perinatal outcomes in twins (n = 181,810 pregnancies) delivered at 32–41 weeks gestation without congenital anomalies. The primary outcome was a composite of perinatal death and severe neonatal morbidity. Cox regression was used to estimate the adjusted hazard ratio (aHR) controlling for the propensity to cesarean delivery, fetal characteristics (sex, birth weight, birth weight discordance, same-sex twin or not) and twin-cluster level dependence. Prospective risks were calculated using the fetuses-at-risk denominators. Results: The overall rates of the primary outcome were slightly lower in intended cesarean (6.20%) vs. vaginal (6.45%) deliveries. The aHRs of the primary outcome were in favor of vaginal delivery at 32 (aHR = 1.06, p = 0.03) or 33 (aHR = 1.22, p<0.001) weeks, neutral at 34–35 weeks, but in favor of cesarean delivery at 36 (aHR = 0.94, p = 0.004), 37, 38 and 39+ weeks (aHR: 0.72 to 0.78, all p<0.001). The lower risk of the primary outcome for cesarean vs. vaginal deliveries at 36+ weeks of gestation remained when the analyses were restricted to different-sex (dichorionic) twins (aHR = 0.84, 95% CI 0.80–0.88). Conclusion: Cesarean delivery may be beneficial for perinatal outcomes overall in twin pregnancies at ≥36 weeks gestation. [ABSTRACT FROM AUTHOR]

To efficiently deliver anti-cancer drug to tumor site and reduce its toxic side effects on normal tissues, a polyethylene glycol (PEG) shielding and tumor microenvironment triggering cascade pH-responsive hollow mesoporous silica nanoparticles (HMSNs) drug delivery system was fabricated. 3-(3, 4-dihydroxyphenyl) propionic acid (DHPA) functionalized beta-cyclodextrin (β-CD) was grafted onto the surfaces of HMSNs via boronic acid-catechol ester bonds. Then, PEG conjugated adamantane (Ada) was anchored on HMSNs-β-CD nanocarrier via host-gust interaction. Various techniques proved the successful fabrication of the system. The in vitro tests confirmed that the system was biocompatible. After the system permeating into tumor via enhanced permeability and retention (EPR) effect, the benzoic-imine bonds between the PEG and Ada were cleaved under weak acid condition in tumor microenvironment (pH 6.8), while the dissociated PEG protective layer facilitating cellular uptake of HMSNs system. Subsequently, the boronic acid-catechol ester bonds linkers further hydrolyzed under even low endosomal pH (4.5–6.5) condition for intracellular drug delivery, leading to efficient cell apoptosis. The in vivo results demonstrated that drug loaded HMSNs significantly inhibited tumor growth while only with minimal toxic side effects. The strategy provides new insight into the development of new generation of drug delivery carriers triggering by tumor microenvironment. [ABSTRACT FROM AUTHOR]

Building insulation materials have a significant effect on the reduction of heating/cooling energy consumptions of buildings. From a life cycle perspective, the comparison of different types of insulation materials should consider the building energy consumption together with the environmental emissions during the manufacturing, production, transportation, using and recycling phases of insulation materials. However, this comparison suffers from many sources of uncertainty, especially the parameter identification of insulation materials. In this study, a life cycle inventory analysis model is established and applied to compare the life cycle performance of eight types of insulation materials in an uncertain framework. For each parameter, a probability density function is explicitly specified through a parameter identification process, and the data uncertainty is propagated by Monte-Carlo simulation, the inventory analysis results are transformed from a concrete value into a probability distribution around a mean value, and sensitivity analysis is implemented to identify uncertainty and variability affecting produced the life cycle assessment (LCA). The simulation results revealed that physical parameters have a significant contribution to the uncertainty of the insulation materials, especially for life cycle energy consumption of glass wool, the maximum value may even be quadrupled compares to the minimum value. The decision maker may change the choice of insulation materials when data uncertainty is taken into consideration in LCA. [ABSTRACT FROM AUTHOR]

For the applicability of dynamic similitude models of thin walled structures, such as engine blades, turbine discs, and cylindrical shells, the dynamic similitude design of typical thin walled structures is investigated. The governing equation of typical thin walled structures is firstly unified, which guides to establishing dynamic scaling laws of typical thin walled structures. Based on the governing equation, geometrically complete scaling law of the typical thin walled structure is derived. In order to determine accurate distorted scaling laws of typical thin walled structures, three principles are proposed and theoretically proved by combining the sensitivity analysis and governing equation. Taking the thin walled annular plate as an example, geometrically complete and distorted scaling laws can be obtained based on the principles of determining dynamic scaling laws. Furthermore, the previous five orders’ accurate distorted scaling laws of thin walled annular plates are presented and numerically validated. Finally, the effectiveness of the similitude design method is validated by experimental annular plates. [ABSTRACT FROM AUTHOR]

Background: Maternal smoking has been associated with elevated risk of type 2 diabetes among the offspring in adulthood. The mechanisms underlying this fetal “programming” effect remain unclear. The present study sought to explore whether maternal smoking affects metabolic health biomarkers in fetuses/newborns. Methods: In a prospective singleton pregnancy cohort (n = 248), we compared metabolic health biomarkers in the newborns of smoking and non-smoking mothers. Outcomes included cord plasma insulin, proinsulin, insulin-like growth factor I (IGF-I), IGF-II, leptin and adiponectin concentrations, glucose-to-insulin ratio (an indicator of insulin sensitivity) and proinsulin-to-insulin ratio (an indicator of β-cell function). Results: Independent of maternal (glucose tolerance, age, ethnicity, parity, education, body mass index, alcohol use) and infant (sex, gestational age, birth weight z score, mode of delivery, cord blood glucose concentration) characteristics, the newborns of smoking mothers had lower IGF-I concentrations (mean: 6.7 vs. 8.4 nmol/L, adjusted p = 0.006), and marginally higher proinsulin-to-insulin ratios (0.94 vs. 0.72, adjusted p = 0.06) than the newborns of non-smoking mothers. Cord plasma insulin, proinsulin, IGF-II, leptin and adiponectin concentrations and glucose-to-insulin ratios were similar in the newborns of smoking and non-smoking mothers. Conclusions: Maternal smoking was associated with decreased fetal IGF-I levels, and borderline lower fetal β-cell function. Larger cohort studies are required to confirm the latter finding. The preliminary findings prompt the hypothesis that these early life metabolic changes may be involved in the impact of maternal smoking on future risk of metabolic syndrome related disorders in the offspring. [ABSTRACT FROM AUTHOR]

Hydroxyl (OH) radicals generated in wire–plate pulsed corona discharge (PCD) were detected by laser-induced fluorescence (LIF). In this paper, the 2-D distribution of OH radicals and the time-resolved development of the streamers in humidified nitrogen were recorded by an intensified charge-coupled device camera. The results indicate that the OH-LIF signals could not be detected when secondary streamer was absent in PCD with low input energy. Input energy, which varies with the configuration of wire–plate reactor and applied voltage, significantly affected the spatial distribution of OH radicals. [ABSTRACT FROM PUBLISHER]

Abstract: In this study, a type of intracellular redox-triggered hollow mesoporous silica nanoreservoirs (HMSNs) with tumor specificity was developed in order to deliver anticancer drug (i.e., doxorubicin (DOX)) to the target tumor cells with high therapeutic efficiency and reduced side effects. Firstly, adamantanamine was grafted onto the orifices of HMSNs using a redox-cleavable disulfide bond as an intermediate linker. Subsequently, a synthetic functional molecule, lactobionic acid-grafted-β-cyclodextrin (β-CD-LA), was immobilized on the surface of HMSNs through specific complexation with the adamantyl group, where β-CD served as an end-capper to keep the loaded drug within HMSNs. β-CD-LA on HMSNs could also act as a targeting agent towards tumor cells (i.e., HepG2 cells), since the lactose group in β-CD-LA is a specific ligand binding with the asialoglycoprotein receptor (ASGP-R) on HepG2 cells. In vitro studies demonstrated that DOX-loaded nanoreservoirs could be selectively endocytosed by HepG2 cells, releasing therapeutic DOX into cytoplasm and efficiently inducing the apoptosis and cell death. In vivo investigations further confirmed that DOX-loaded nanoreservoirs could permeate into the tumor sites and actively interact with tumor cells, which inhibited the tumor growth with the minimized side effect. On the whole, this drug delivery system exhibits a great potential as an efficient carrier for targeted tumor therapy in vitro and in vivo. [Copyright &y& Elsevier]

Breast cancer (BC) is a malignant disease and the most commonly diagnosed cancer in women. Numerous studies have previously verified the important role of long non-coding RNAs in a number of biological processes in BC. In the present study, analysis of The Cancer Genome Atlas database and reverse transcription-quantitative PCR demonstrated that LOC102724163 expression levels were significantly upregulated in BC tissues compared to matched adjacent normal tissues and were associated with an unfavorable prognosis in patients with BC. Gain or loss of function assays indicated that overexpression of LOC102724163 significantly increased tumorgenicity in vivo and cell migration, proliferation and invasion in vitro. In the mechanistical aspect, LOC102724163 sponged microRNA (miR)-508-5p to elevate MUC19 expression. Additionally, rescue assays ascertained the function of the LOC102724163/miR-508-5p/MUC19 axis in the proliferation and invasion of BC cells. To the best of our knowledge, this is the first study to have demonstrated that LOC102724163 may act as a competing endogenous RNA to control MUC19 expression levels by competitively sponging miR-508-5p to modulate BC progression. Therefore, the present study has provided new insights into BC diagnosis and treatment. [ABSTRACT FROM AUTHOR]

The dual-rotor system has been widely used in aero-engines and has the characteristics of large axial size, the interaction between the high-pressure rotor and low-pressure rotor, and stiffness nonlinearity of bolted joints. However, the testing of a full-scale dual-rotor system is expensive and time-consuming. In this paper, the scaling relationships for the dual-rotor system with bolted joints are proposed for predicting the responses of full-scale structure, which are developed by generalized and fundamental equations of substructures (shaft, disk, and bolted joints). Different materials between prototype and model are considered in the derived scaling relationships. Moreover, the effects of bolted joints on the dual-rotor system are analyzed to demonstrate the necessity for considering bolted joints in the similitude procedure. Furthermore, the dynamic characteristics for different working conditions (low-pressure rotor excitation, high-pressure rotor excitation, two frequency excitations, and counter-rotation) are predicted by the scaled model made of a relatively cheap material. The results show that the critical speeds, vibration responses, and frequency components can be predicted with good accuracy, even though the scaled model is made of different materials. [ABSTRACT FROM AUTHOR]

Pulsed corona discharge has been proved to be effective in the treatment of gas pollutions ejected from flue gas. In this paper, chemical characteristics of pulsed corona discharge plasma and its application of nitric oxide (NO) conversion process are investigated with different gas mixtures. The NO conversion efficiency increases with the increasing oxygen concentration and relative humidity, which can be achieved up to 98.3% when oxygen concentration is 21.3%, while the single pulse energy is only 0.29 J. Possible reaction pathways of the NO conversion process in the plasma generated by different gases are also proposed. In the pulse corona discharge, the NO conversion process is mainly governed by reactions with oxygen-derived radicals. OH radical is considered to be the most important radical in NO oxidation process in H2O/N2 mixture. However, it has a little influence on NO conversion in rich oxygen atmosphere. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the hydrodynamic and thermal performance of nanofluids in the region of thermal developing laminar mixed convection. Single-phase approach was employed to evaluate the pumping power and heat transfer coefficient, i.e., no novel mechanism other than the renewing thermophysical properties of nanofluids was involved. An aggregation-mechanism-based methodology was introduced and verified to well unify the rheological and thermal properties of nanofluids. In comparing the pumping power savings, critical differences between forced convection and mixed convection were found: nanofluids are more favorable for application to mixed convection. Criteria for nanofluid forced-mixed transition have been discussed and presented to help the decision of whether a flow can be viewed as mixed flow. [Copyright &y& Elsevier]

• This paper proposes a method to obtain scaling laws for rotor systems. • This paper proposes frequency adjustment laws for predicting responses in non-resonant state. • The proposed method provides several scaling laws in whole range of rotating speed. • Experimental testing for vibration responses of prototype and model is carried out. • The proposed method can improve prediction accuracy compared with existing methods. Similitude theory provides the necessary conditions to predict the structural responses of the full-scale prototype through the scaled model, and is widely used in full-scale experiments of large structures. However, the prediction accuracy is insufficient in partial similitude. Aiming at this issue, this paper proposes the frequency adjustment laws to predict vibration responses of full-scale rotor in non-resonant state, since the rotating machinery usually works in non-resonant state. On this basis, a partial similitude method is presented by combining the frequency adjustment laws with the current method. The proposed method provides several scaling laws in the whole range of rotating speed, while only one scaling factor is used to predict the vibration responses in existing methods. The accuracy of the proposed method is verified by the numerical and experimental case studies, where the geometrical distortion is considered. In the numerical case study, the scaling laws of a rotor system are obtained by the proposed method and existing methods. The predicted results of the proposed method are compared with those of the existing methods. It is found the proposed method accurately predicts the displacements and accelerations of prototypes through those of scaled model. Moreover, the proposed method achieves a higher accuracy. The experimental study carries out the testing for the prototype and model test rigs. The experimental results show that the proposed method provides better results in predicting the displacement and acceleration compared with the existing methods. The proposed method allows designers to design a scaled model and to reproduce the vibratory behavior of the full-size prototype, which reduces the difficulty, costs and time of experimental test. Moreover, the proposed partial similitude method has a better performance than the existing methods. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: In circumpolar countries such as Canada,northern regions represent a unique geographical entity climatically, socioeconomically and environmentally.There is a lack of comparative data on birth outcomes among Indigenous and non-Indigenous subpopulations within northern regions and compared with southern regions.Methods: A cohort study of all births by maternal mother tongue to residents of northern (2616 First Nations(North American Indians), 2388 Inuit and 5006 non-Indigenous) and southern (2563 First Nations, 810 643non-Indigenous) Quebec, 1991-2000.Results: Compared with births to southern non-Indigenous mother tongue women, births to northern women of all three mother tongue groups were at substantially elevated risks of infant death (adjusted OR (aOR) 1.7-2.9), especially post neonatal death (aOR2.2-4.4) after controlling for maternal education, age,marital status and parity. The risk elevation in perinatal death was greater for southern First Nations (aOR 1.6)than for northern First Nations (aOR 1.2). Infant macrosomia was highly prevalent among First Nations in Quebec, especially in the north (31% vs 24% in the south). Within northern regions, Inuit births were at highest risk of preterm delivery (aOR 1.4) and infant death (aOR 1.6).Conclusion: All northern infants (First Nations, Inuit or non-Indigenous) were at substantially elevated risk of infant death in Quebec, despite a universal health insurance system. Southern First Nations newborns have not benefited from the more advanced perinatal care facilities in southern regions. Environmental influences may partly account for the very high prevalence of macrosomia among First Nations in northern Quebec. [ABSTRACT FROM AUTHOR]

The wire–plate pulsed corona discharge reactor has been regarded as the plasma reactor with highest efficiency for controlling pollutants such as NO and \SO2 in flue gas with high-voltage and short-duration positive pulsed corona discharge. A laboratory-scale pulsed corona discharge reactor with wire–plate electrode configuration is established for optimizing the geometry structure of the wire–plate plasma reactor. In this paper, three different methods are used to optimize the wire-to-wire distance and wire-to-plate distance of the plasma reactor. There are experiments with different conditions including various electrical parameters, streamer parameters, and NO oxidation efficiency. The same results are obtained from all the three experiments. The results indicate that short wire-to-plate distance should be adopted to increase the input energy of the plasma reactor but not too short to cause spark discharge in the reactor. Moreover, the wire-to-wire distance should be at least twice as large as wire-to-plate distance, to reduce the interferences between adjacent wire electrodes. [ABSTRACT FROM PUBLISHER]

In this paper, the dynamical performance of polishing robot working in unstructured environment is investigated. Structure mechanism and operating principle of a polishing robot are introduced firstly, and its dynamical model is established. Then, a S-shaped acceleration-deceleration path planning method and a human-simulated intelligent control (HSIC) strategy are proposed. The S-shaped acceleration-deceleration path planning method is to switch the magnitude and direction of the abrupt velocities between motion sections in order to improve the work efficiency, the smoothness of movement and the processing accuracy. The HSIC control strategy is built based on the unstructured environment information measured by ultrasonic sensors, in which the appropriate programs prepared in advance are determined according to the size and sign of both the control error and its change rate. Simulation results show that the intelligent control strategy combining with optimum path planning method are effective to reduce the structure vibration, to improve the stability and the control accuracy of the polishing robot system. [ABSTRACT FROM AUTHOR]

OBJECTIVE -- Offspring of mothers with impaired glucose tolerance are far more likely to develop type 2 diabetes. We tested the hypothesis that maternal glucose tolerance in pregnancy affects fetal insulin sensitivity or β-cell function. RESEARCH DESIGN AND METHODS-- In a prospective singleton pregnancy cohort study, we analyzed glucose, insulin, and proinsulin concentrations in maternal blood at the 50-g oral glucose tolerance test (OGTT) at 24-28 weeks of gestation and in venous cord blood (n = 248). The cord blood glucose-to-insulin ratio and proinsulin concentration were used as indicators of fetal insulin sensitivity and the proinsulin-to-insulin ratio was used as an indicator of fetal β-cell function. RESULTS -- Higher OGTT blood glucose levels were associated with significantly lower cord plasma glucose-to-insulin ratios (r = -0.31, P < 0.001) and higher proinsulin concentrations (r = 0.31, P < 0.001) but not with proinsulin-to-insulin ratios. In a comparison of gestational diabetic (n = 26) versus euglycemic pregnancy, cord blood glucose-to-insulin ratios were substantially lower (geometric mean 10.1 vs. 20.0 mg/dl/µU/ml; P < 0.001), whereas proinsulin concentrations were much higher (24.4 vs. 13.8 pmol/l; P < 0.001), despite similar cord blood glucose concentrations indicating adequate management of diabetes. The differences remained significant after controlling for pre-pregnancy and fetal adiposity, family history of diabetes, gestational age, and other potential confounders. Significant changes in the glucose-to-insulin ratio and proinsulin concentration were also observed in obese (n = 31) mothers, but the differences became not statistically significant after adjustment for maternal glucose tolerance and fetal adiposity. CONCLUSIONS- Maternal glucose intolerance may impair fetal insulin sensitivity (but not β-cell function) and consequently "program" the susceptibility to type 2 diabetes. [ABSTRACT FROM AUTHOR]

In this study, a novel variable-stiffness structure (VSS) featuring temperature-dependent characteristics is introduced for the optical payload of the Jilin1-GF04X satellite, which has an image resolution of 0.3 m. The VSS, constructed from polyurethane material, was engineered to operate at room temperature (22 °C) during the rocket launch phase in order to withstand adverse dynamic conditions. Additionally, the structure was designed to function at a higher temperature (35 °C) while in orbit to improve the efficiency of microvibration isolation. The assessment of the suppression capabilities of the presented vibration isolator, as compared to the present carbon fiber structure, was conducted through an integrated analysis. Ground-based microvibration tests were subsequently carried out to evaluate the capacity of the VSS for adjusting its stiffness and damping properties. The results showed that the maximum amplitude of pixel offset reduced by 27.6% at 35 °C compared to 22 °C, confirming the efficacy of the structure. • A variable-stiffness structure (VSS) featuring temperature-dependent characteristics is proposed. • The dynamic properties of polyurethane materials are characterized using the fractional derivative constitutive equation. • The integrated model is established by the optical model, structural model, control model of the satellite and the perturbations of the flywheel. • Ground-based microvibration tests are carried out to evaluate the capacity of the VSS for adjusting its stiffness and damping properties. [ABSTRACT FROM AUTHOR]

Background: Bone marrow mesenchymal stem cells (BMSCs) can undergo inadequate osteogenesis or excessive adipogenesis as they age due to changes in the bone microenvironment, ultimately resulting in decreased bone density and elevated risk of fractures in senile osteoporosis. This study aims to investigate the effects of osteocyte senescence on the bone microenvironment and its influence on BMSCs during aging. Results: Primary osteocytes were isolated from 2-month-old and 16-month-old mice to obtain young osteocyte-derived extracellular vesicles (YO-EVs) and senescent osteocyte-derived EVs (SO-EVs), respectively. YO-EVs were found to significantly increase alkaline phosphatase activity, mineralization deposition, and the expression of osteogenesis-related genes in BMSCs, while SO-EVs promoted BMSC adipogenesis. Neither YO-EVs nor SO-EVs exerted an effect on the osteoclastogenesis of primary macrophages/monocytes. Our constructed transgenic mice, designed to trace osteocyte-derived EV distribution, revealed abundant osteocyte-derived EVs embedded in the bone matrix. Moreover, mature osteoclasts were found to release osteocyte-derived EVs from bone slices, playing a pivotal role in regulating the functions of the surrounding culture medium. Following intravenous injection into young and elderly mouse models, YO-EVs demonstrated a significant enhancement of bone mass and biomechanical strength compared to SO-EVs. Immunostaining of bone sections revealed that YO-EV treatment augmented the number of osteoblasts on the bone surface, while SO-EV treatment promoted adipocyte formation in the bone marrow. Proteomics analysis of YO-EVs and SO-EVs showed that tropomyosin-1 (TPM1) was enriched in YO-EVs, which increased the matrix stiffness of BMSCs, consequently promoting osteogenesis. Specifically, the siRNA-mediated depletion of Tpm1 eliminated pro-osteogenic activity of YO-EVs both in vitro and in vivo. Conclusions: Our findings suggested that YO-EVs played a crucial role in maintaining the balance between bone resorption and formation, and their pro-osteogenic activity declining with aging. Therefore, YO-EVs and the delivered TPM1 hold potential as therapeutic targets for senile osteoporosis. [ABSTRACT FROM AUTHOR]

Spacecraft are subjected to a harsh and complex dynamic environment during launch and on-orbit operation, necessitating the use of vibration isolation techniques to protect the onboard components and the payload from harmful vibration. Moreover, the stringent requirements for modern spacecraft's payload stability and pointing accuracy have fueled research for higher-performance vibration isolation. Consequently, a number of vibration isolation systems based on active, passive, semi-active, and hybrid isolation methods have been proposed. This study employed a systematic literature review methodology to examine the most recent methods for vibration isolation in spacecraft, taking into account both whole-spacecraft vibration isolation (WSVI) and microvibration isolation (MVI) and primarily referencing works published in the literature between 2012 and 2022. The review highlighted current research trends in vibration isolation methods and implementation strategies reported in the literature, as well as the status of research on WSVI and MVI. The findings suggest that more research was conducted in the domain of MVI compared to WSVI, with passive techniques accounting for about 42 % of the articles reviewed. This could be attributed to the advances made in smart materials, metamaterials, and the quasi-zero-stiffness concept to address the shortcomings of traditional passive isolators. To this end, remarks on the limitations of the current studies and future prospects were highlighted. [ABSTRACT FROM AUTHOR]

In this paper, some important properties of orthogonal polynomials of two variables are investigated. The concepts of invariant factor for orthogonal polynomials of two variables are introduced. The presented results include Stieltjies type theorems for multivariate orthogonal polynomials and the corresponding asymptotic expansion formulas. [Copyright &y& Elsevier]

The organic-rich shale of the Qingshankou Formation (K2qn) is the most important target in the Songliao Basin. The relationship between lithofacies and source rock quality, however, is still controversial. Core observation, thin section identification, X-ray diffraction, organic geochemistry, and other analytical methods were adopted to investigate the petrology and its effects on hydrocarbon potential of the Qingshankou shale. Based on the differences in minerals, bioclastic, and fabric of laminae, four main lithofacies were defined as: (i) felsic shale (FS), (ii) clay shale (CS), (iii) bio-bearing shale (BS), and (iv) mixed shale (MS). The clay minerals content in the CS (average: 46.72 wt%) and MS (average: 41.11 wt%) was higher than that in FS (average: 39.97 wt%) and BS (average: 35.48 wt%). This classification allows the following comparative quantification of total organic carbon (TOC) content to be differentiated: CS > BS > MS > FS. Geochemical analysis indicated that the oil generation potential of the CS was the best, and the hydrocarbons generated from CS might migrate and accumulate in other lithofacies. All this knowledge could shed light on the lithofacies classification in shale systems with high clay mineral content, and may provide references for sweet spotting of the Qingshankou Formation in the Songliao Basin. [ABSTRACT FROM AUTHOR]