Search

Abstract Background The National Chest Pain Center Program (NCPCP) is a nationwide, quality enhancement program aimed at raising the standard of care for patients experiencing acute chest pain in China. The benefits of chest pain center (CPC) accreditation on acute coronary syndrome have been demonstrated. However, there is no evidence to indicate whether CPC accreditation improves outcomes for patients with acute aortic dissection (AAD). Methods We conducted a retrospective observational study of patients with AAD from 1671 hospitals in China, using data from the NCPCP spanning the period from January 1, 2016 to December 31, 2022. The patients were divided into 2 groups: pre-accreditation and post-accreditation admissions. The outcomes examined included in-hospital mortality, misdiagnosis, and Stanford type A AAD surgery. Multivariate logistic regression was employed to explore the relationship between CPC accreditation and in-hospital outcomes. Furthermore, we stratified the hospitals based on their geographical location (Eastern/Central/Western regions) or administrative status (provincial/non-provincial capital areas) to assess the impact of CPC accreditation on AAD patients across various regions. Results The analysis encompassed a total of 40,848 patients diagnosed with AAD. The post-accreditation group exhibited significantly lower rates of in-hospital mortality and misdiagnosis (12.1% vs. 16.3%, P

In our study, we compared classical genetic algorithm (GA) and non-dominated sorting GA (NSGA) II to optimize LQR and sliding mode control (SMC) for an inverted pendulum. We aimed to identify the algorithm that best improves stability and peak performance. Our results clarified each algorithm’s unique strengths. The provement is shown in Matlab simulations.

This paper surveys the Linear Quadratic Estimation (LQE) and Model Predictive Control (MPC) discrete control methods applied to the Acrobot system. Both techniques aim to achieve and maintain a balanced position for the Acrobot. Through evaluation and comparison, we highlight their strengths, limitations, and potential applications, offering insights for future robotic control research.

This article aims to develop a new Adaptive Proportional Integral Derivative (PID) Nonsingular Dual Terminal Sliding Mode Control, designed for tracking the position of robot manipulators under disturbances and uncertainties. Compared with existing PID Nonsingular Fast Terminal Sliding Mode (PIDNFTSM) controllers, this work effectively avoids singularity problems in control while significantly enhancing the convergence speed of errors. An adaptive reaching law is proposed to estimate the bound information of the first derivative of lumped disturbance by regulating itself based on sliding variables. The overall system stability is proven by using the Lyapunov approach. Subsequent simulation results verify the effectiveness of the proposed controller regarding tracking error reduction, energy efficiency enhancements, and singularity avoidance.

This study investigates how binding/unbinding kinetics of a benzimidazole-derivative DNA inhibitor in E. coli cells depends on cell growth and physiology and demonstrates the effect of this coupling on drug efficacy.

This paper aims to develop a novel hierarchical recursive nonsingular terminal sliding mode controller (HRNTSMC), which is designed to stabilize the inverted pendulum (IP). In contrast to existing hierarchical sliding mode controllers (HSMC), the HRNTSMC significantly reduces the chattering problem in control input and improves the convergence speed of errors. In the HRNTSMC design, the IP system is first decoupled into pendulum and cart subsystems. Subsequently, a recursive nonsingular terminal sliding mode controller (RNTSMC) surface is devised for each subsystem to enhance the error convergence rate and attenuate chattering effects. Following this design, the HRNTSMC surface is constructed by the linear combination of the RNTSMC surfaces. Ultimately, the control law of the HRNTSMC is synthesized using the Lyapunov theorem to ensure that the system states converge to zero within a finite time. By invoking disturbances estimation, a linear extended state observer (LESO) is developed for the IP system. To validate the effectiveness, simulation results, including comparison with a conventional hierarchical sliding mode control (CHSMC) and a hierarchical nonsingular terminal sliding mode control (HNTSMC) are presented. These results clearly showcase the excellent performance of this approach, which is characterized by its strong robustness, fast convergence, high tracking accuracy, and reduced chattering in control input.

To evaluate optimizing processing conditions for bismuth ferrite BiFeO3 (BFO) thin films with thicknesses below 200 nm on Pt(111)/Ti/SiO2/Si substrates. The impact of the amorphous components, as well as defects and elemental composition changes and microstructure evolution (i.e., grain size) as regulated by the treatment temperatures (475–600°C) on the ferroelectric and dielectric properties are investigated. The current work shows that with the smallest grain size and the least defects amount achieved in the film annealed at 550°C, the conductivity is compressed greatly. Such a temperature will also allow adequate ferroelectric switching by reducing the amorphous components, which remain the majority below 500°C and thus reinforce the polarization switching. The leakage path is deduced via crystallized grains in BFO thin films instead of the remaining including grain boundaries and amorphous components. The best remanent polarization of ∼60.4 μC·cm‐2 from PUND measurements excluding the leakage contribution at 500 kV·cm−1 and an excellent fatigue property of 106 cycles are achieved. In addition, broadened fabrication temperatures for amorphous‐protected polycrystalline BFO thin films from 525 to 575°C, exhibiting superior ferroelectricity than most previously reported BFO thin films below 200 nm, either derived by chemical or physical methods. Ultimately, it is suggested that for leaky ferroelectrics such as BFO, optimal annealing temperature should balance the amorphous components by reducing the annealing temperature while maintaining adequate crystallization for ferroelectric switching. [ABSTRACT FROM AUTHOR]

This paper investigates firm heterogeneity in total factor productivity across Vietnam domestic private sector with sixteen manufacturing subindustries over the period 2010-2016, with a focus on labor size and based on total factor productivity (TFP); including TFP level, TFP distance, and TFP dispersion. Our results indicate that, in the private sector, labor heterogeneity on productivity are very dependent on specific manufacturing sectors, and on type of TFP. From an industrial policy perspective, there is hence productivity related reason on why Vietnamese policy makers should prefer large and extremely large firms over small and medium enterprises (SMEs) in some manufacturing and vice versa. Our results provide a support for both SMEs and large private consortiums, depending on specific manufacturing sectors. In addition, since there is a strong evidence to suggest that labor heterogeneity in TFP exists in some manufacturing sectors, the rationality behind policies to support SMEs and large firms at every manufacturing sectors seems to be questionable.

BackgroundMedical students are known to have higher levels of these issues than the general population but in Vietnam the effects of the pandemic on medical student mental health was not documented.ObjectivesTo estimate the prevalence and identify factors associated with self-reported anxiety disorder, depression, and perception of worsening mental health among Vietnamese medical students during the COVID-19 pandemic.MethodA cross-sectional study was conducted from April 7th to 29th, 2020. All students in Doctor of General Medicine, Doctor of Preventive Medicine, and Bachelor of Nursing tracks at Hanoi Medical University (3672 students) were invited to participate. Data were collected using an online questionnaire including demographic characteristics, Generalized Anxiety Disorder 7 items, Patient Health Questionnaire 9 items, Fear of COVID-19 scale, and question about worsening mental health status. Robust Poisson regression was used to assess the association between mental health status and associated factors.ResultsAmong 1583 students (43.1% response rate), the prevalence of students screened positive for anxiety disorder was 7.3%(95%C.I.:6.0-8.7), depression was 14.5%(95%C.I.:12.8-16.3), and perceiving worsening mental health was 6.9%(95%C.I.:5.7-8.3). In multivariable regression models, significant factors associated with self-reported anxiety disorder included being male (PR = 1.99,95%C.I.:1.35-2.92), difficulty in paying for healthcare services (PR = 2.05,95%C.I.:1.39-3.01), and high level of fear of COVID-19 (Q3:PR = 2.36,95%C.I.:1.38-4.02 and Q4:PR = 4.75,95%C.I.:2.65-8.49). Significant factors associated with self-reported depression were difficulty in paying for healthcare services (PR = 1.78,95%C.I.:1.37-2.30), and high level of fear of COVID-19 (Q3:PR = 1.41,95%C.I.:1.02-1.95 and Q4:PR = 2.23,95%C.I.:1.51-3.29). Significant factors associated with perceived worsening mental health status included having clinical experience (PR = 1.83,95%C.I.:1.17-2.88) and having atypical symptoms of COVID-19 (PR = 1.96,95%C.I.:1.31-2.94).ConclusionThe prevalence of self-reported depression, anxiety disorder, and worsening mental health among Vietnamese students during the first wave of COVID-19 was lower than in medical students in other countries. Further investigation is needed to confirm this finding.

ABSTRACT Various toxic compounds disrupt bacterial physiology. While bacteria harbor defense mechanisms to mitigate the toxicity, these mechanisms are often coupled to the physiological state of the cells and become ineffective when the physiology is severely disrupted. Here, we characterized such feedback by exposing Escherichia coli to protonophores. Protonophores dissipate the proton motive force (PMF), a fundamental force that drives physiological functions. We found that E. coli cells responded to protonophores heterogeneously, resulting in bimodal distributions of cell growth, substrate transport, and motility. Furthermore, we showed that this heterogeneous response required active efflux systems. The analysis of underlying interactions indicated the heterogeneous response results from efflux-mediated positive feedback between PMF and protonophores’ action. Our studies have broad implications for bacterial adaptation to stress, including antibiotics. IMPORTANCE An electrochemical proton gradient across the cytoplasmic membrane, alternatively known as proton motive force, energizes vital cellular processes in bacteria, including ATP synthesis, nutrient uptake, and cell division. Therefore, a wide range of organisms produce the agents that collapse the proton motive force, protonophores, to gain a competitive advantage. Studies have shown that protonophores have significant effects on microbial competition, host-pathogen interaction, and antibiotic action and resistance. Furthermore, protonophores are extensively used in various laboratory studies to perturb bacterial physiology. Here, we have characterized cell growth, substrate transport, and motility of Escherichia coli cells exposed to protonophores. Our findings demonstrate heterogeneous effects of protonophores on cell physiology and the underlying mechanism.

This paper proposes a robust protection technology to enhance the grid-connected capability of the doubly fed induction generator (DFIG) based on wind turbines (WTs) under low voltage ride through (LVRT) conditions. The proposed method to control the rotor side converter (RSC) and grid side converter (GSC) uses proportional–integral (PI) controllers. The protection devices are the static compensator (STATCOM), crowbar, series dynamic resistor (SDR), and DC-chopper, with the proposed method to control STATCOM using proportional–integral (PI) controllers and the proposed method to control the rest of the protection devices based on the allowable threshold values of rotor current and DC-link voltage. The protection coordination strategy between them is proposed to avoid the disconnection between the rotor circuit and grid, maintain the DC-link at constant voltage, enhance the dynamic response of WT, and improve the voltage response at the point of common coupling (PCC) of WT. The DFIG-WT of 2 MW-575 V connecting to the 34-bus IEEE network is carried out to verify the effectiveness of the proposed method under the conditions of symmetrical and asymmetrical faults, and the LVRT requirements of the Spanish grid code are considered. The obtained simulation results using the PSCAD/EMTDC software show that the rotor current, DC-link voltage, voltage PCC, and power oscillation damping are significantly improved compared to not using it or applying the conventional method based on passivity theory. Therefore, the LVRT capability of the proposed DFIG-WT system is significantly enhanced, and it has enough ability to continue to provide electrical energy to the power network. [ABSTRACT FROM AUTHOR]

Surface modified nano-flake Cu powder was prepared by plasma assisted ball milling by adding stearic acid as a process agent and its tribological properties were tested. The results indicate that the Cu particle exhibiting an excellent superplasticity has severe plastic deformation induced by a synergistic effect of plasma high-rate heating and electroplasticity, and the 20nm-thick flake-like Cu particles are obtained after 5h milling time of plasma milling. These nano-flake Cu particles owning oleophobicity characteristics exhibit good dispersion in the 40CA marine lubricating oil due to that the surface of Cu nano-flake adsorbs and chemically bonds with some non-polar groups under the plasma assisted ball milling with stearic acid. The severe deformation of the nano-flake Cu particles displaying high activation are easily adsorbed and spread on the surface of the friction counterpart in the process of sliding, which promotes a better wear resistance for compound lubricant with nano-flake Cu addition. Under a high rotating speed and excessive load, the nano-flake Cu powder provides excellent friction-reducing and self-repairing characters and improves the anti-wear performance under an extreme pressure condition.

In this experimental investigation, a core–shell-structured nano-lubricating additive was synthesized utilizing the dielectric barrier discharge plasma (DBDP)-assisted ball grinding technique for a duration of 5 h. The microstructural analysis of the nano-TiO2 powder was performed employing advanced methods such as X-ray diffraction (XRD) and thermogravimetry–differential scanning calorimetry (TG-DSC). The initial particle size of TiO2 was refined from 1 μm to a range of 150–200 nm, resulting in a remarkable increase in lattice distortion rate by 88.2% and an oil affinity enhancement of 200%. Through the introduction of CTAB's oil-compatible group onto the surface of nano-TiO2 particles, a modified layer with a thickness of 21 nm possessing superior thermal stability and an activation energy (Ea) of 600 kJ/mol was successfully produced. Molecular dynamics simulations were conducted to elucidate the mechanism underlying the surface modification of nano-TiO2 powder facilitated by DBDP-assisted ball grinding, thereby revealing the pivotal role of electrostatic forces in the organic modification of the TiO2 surface. It was found that electrostatic forces dominantly govern the cetyl trimethyl ammonium bromide (CTAB)–TiO2 composite interface model, contributing to 70% of the total energy with a maximum energy proportion of −187.84 kcal/mol. To evaluate the lubrication performance of the composite oil samples under boundary lubrication conditions, comprehensive assessments were carried out using the four-ball method and reciprocating friction experiments. The results demonstrated noteworthy enhancements in viscosity index, dynamic viscosity, and oil film thickness within the composite oil samples. Particularly, the composite oil containing 0.5 wt % TiO2@CTAB exhibited outstanding extreme pressure resistance, manifesting a significant reduction of 41.7% in the average friction coefficient, a considerable increase of 25.8% in wear spot diameter, and a substantial elevation of 66.9% in maximum nonseizure load. Compared to the base oil, the incorporation of 0.5 wt % TiO2@CTAB led to a notable increment of 34.7% in oil film thickness, 6.7% in dynamic viscosity, and 9% in viscosity index. In the tribological experiment simulating marine diesel engines, the friction coefficient witnessed a remarkable reduction by 65.8%, accompanied by a substantial decrease of 54.1% in wear rate. This noteworthy improvement in boundary lubrication conditions of the friction pair effectively mitigated friction and wear. For comprehensive characterization of the wear marks, energy-dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS) techniques were employed to analyze the physical structure and chemical composition. The implementation of TiO2@CTAB nano-lubricating additives resulted in nanobearing and deposition effects, leading to a reduction in contact area and surface roughness, thereby facilitating the restoration of the friction pairs. These findings possess significant implications for extending the service life of diesel engines and ensuring safe navigation. Furthermore, these studies underscore the considerable potential of core–shell-structured TiO2@CTAB for widespread application in diesel engines. [ABSTRACT FROM AUTHOR]