This paper studies the optimal control problem of random impulsive differential equations. Based on the influence of random impulse generation, we define a more reasonable performance index by ...setting the random function and obtain the HJB equation of random impulse. Using the basic analysis method and stochastic process theory, we prove that the value function satisfies the random impulse HJB equation, and the value function is the viscosity solution of the random impulse HJB. As an application, we present an example of optimal feedback control.
The antibacterial activity and acting mechanism of silver nanoparticles (SNPs) on Escherichia coli ATCC 8739 were investigated in this study by analyzing the growth, permeability, and morphology of ...the bacterial cells following treatment with SNPs. The experimental results indicated 10 μg/ml SNPs could completely inhibit the growth of 10⁷ cfu/ml E. coli cells in liquid Mueller-Hinton medium. Meanwhile, SNPs resulted in the leakage of reducing sugars and proteins and induced the respiratory chain dehydrogenases into inactive state, suggesting that SNPs were able to destroy the permeability of the bacterial membranes. When the cells of E. coli were exposed to 50 μg/ml SNPs, many pits and gaps were observed in bacterial cells by transmission electron microscopy and scanning electron microscopy, and the cell membrane was fragmentary, indicating the bacterial cells were damaged severely. After being exposed to 10 μg/ml SNPs, the membrane vesicles were dissolved and dispersed, and their membrane components became disorganized and scattered from their original ordered and close arrangement based on TEM observation. In conclusion, the combined results suggested that SNPs may damage the structure of bacterial cell membrane and depress the activity of some membranous enzymes, which cause E. coli bacteria to die eventually.
Background
Circulating tumor DNA (ctDNA) has emerged as a noninvasive biomarker for dynamically monitoring tumors. However, published data on perioperative ctDNA in patients with operable non–small ...cell lung cancer (NSCLC) are currently limited.
Methods
This prospective study recruited 123 patients with resectable stage I to IIIA NSCLC. Preoperative and postoperative plasma samples and tumor tissue samples were subjected to next‐generation sequencing with a panel of 425 cancer‐related genes. Peripheral blood samples were collected before surgery, postoperatively within 1 month, and every 3 to 6 months for up to 3 years.
Results
After 4 exclusions, 119 eligible patients were enrolled from June 2016 to February 2019. Presurgical ctDNA was detectable in 29 of 117 patients (24.8%) and was associated with inferior recurrence‐free survival (RFS; hazard ratio HR, 2.42; 95% CI, 1.11‐5.27; P = .022) and inferior overall survival (OS; HR, 5.54; 95% CI, 1.01‐30.35; P = .026). Similarly, ctDNA was detected in 12 of 116 first postsurgical samples (10.3%) and was associated with shorter RFS (HR, 3.04; 95% CI, 1.22‐7.58; P = .012). During surveillance after surgery, longitudinal ctDNA–positive patients (37 of 119; 31.1%) had significantly shorter RFS (HR, 3.46; 95% CI, 1.59‐7.55; P < .001) and significantly shorter OS (HR, 9.99; 95% CI, 1.17‐85.78; P = .010) in comparison with longitudinal ctDNA–negative patients. Serial ctDNA detection preceded radiologic disease recurrence by a median lead time of 8.71 months.
Conclusions
These results suggest that perioperative ctDNA analyses can predict recurrence and survival, and serial ctDNA analyses can identify disease recurrence/metastasis earlier than routine radiologic imaging in patients with resectable NSCLC.
Lay Summary
The utility of serial circulating tumor DNA (ctDNA) monitoring for predicting disease recurrence and survival for early‐stage non–small cell lung cancer (NSCLC) has not been well characterized.
The detection of ctDNA before and after surgery is associated with the identification of a high risk of disease recurrence and long‐term patient outcomes for resectable NSCLC.
Perioperative ctDNA analyses identify disease recurrence earlier than routine radiologic imaging. ctDNA analyses can detect minimal residual disease for resectable NSCLC and thus can facilitate early intervention.
Perioperative circulating tumor DNA (ctDNA) analyses identify disease recurrence earlier than routine radiologic imaging. ctDNA analyses can detect minimal residual disease for resectable non–small cell lung cancer and thus can facilitate early intervention.
The magnetic topological van der Waals materials family MnBi2Te4/(Bi2Te3)n have drawn markedly attention due to their novel multiple topological phases in different magnetic configurations. Recently, ...their close relative, the MnSb4Te7, was firstly synthesized in experiments (2021 Phys. Rev. Lett. 126 246601). To further explore the emergent properties of MnSb4Te7, we have systematically investigated the magnetic and topological characters under compressive strain and charge doping using first-principles calculations. We predict that MnSb4Te7 transits from an interlayer antiferromagnetic ground state to a ferromagnetic semimetal ground state with multiple Weyl points when compressive strained along c axis above 8% or charge doping before 0.1 hole/formula concentration. Notable anomalous Hall conductivity is also predicted. Meanwhile, the magnetic easy axis can be reoriented from out-of-plane to in-plane orientation when strain or electron doping is applied. The underlying magnetic exchange mechanism is also analyzed from our calculation results. Our work thus provides a feasible way to realize applications of the highly tunable magnetic-topological nature and a comprehensive theoretical understanding of this magnetic topological material.
The successful experimental syntheses of two-dimensional (2D) boron allotropes with intriguing properties have stimulated great interest in searching for novel low-dimensional boron. By using ...high-throughput first-principles calculations, we proposed a new stable 2D boron with a bilayer structure (P6̅-boron), composed of the building blocks of buckled B12 cluster. We showed the possibility of experimental syntheses of P6̅-boron on metal substrates and proposed a strategy to pursue for P6̅-boron by the B12 clusters self-assembly. Specifically, P6̅-boron possesses a topologically nontrivial Dirac nodal line, which is protected by the mirror-reflection symmetry. Furthermore, we employed a low-energy effective k·p model to prove the existence of the nodal line solution. In addition, the topological analysis of bonding suggests that the chemical bonds of P6̅-boron are all covalent rather than ionic bonds found in bilayer P6/mmm boron. We expect that our findings can favor the low-dissipation high-speed nanoelectronic devices based on 2D boron sheets.
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