Insights into Cronobacter sakazakii Biofilm Formation and Control Strategies in the Food Industry

Cronobacter sakazakii(C.sakazakii)is a foodborne opportunistic pathogen that can cause life-threatening invasive diseases,such as necrotizing enterocolitis,meningitis,and sepsis in infants.The potential risk of C.sakazakii contamination of powdered infant formula(PIF)is an issue that has attracted considerable attention from manufacturers,regulators,and consumers.C.sakazakii biofilms on the surfaces of equipment and in diverse food-production environments constitute a mode of cell growth that protects the pathogen from hostile environments,and are an important source of persistent contamination of food products.Bacterial biofilms are difficult to remove due to their resistant properties.Conventional cleaning and sterilizing procedures may be insufficient for biofilm control,and may lead to further biofilm development and dispersal.Consequently,novel control strategies are being developed,such as nanotechnology-based delivery systems,interspecies interactions,antimicrobial molecules of microbial origin,natural extracts,and phages.This review focuses on describing the mechanisms underlying the biofilm formation and behavior of C.sakazakii and discussing potential control strategies.

The Low-Frequency Oscillation Restrain Method Research of Converter-Fed Multi-Phase Induction Motor Propulsion system

The inverter-fed induction motor drive system may become unstable at low frequencies and light load, and phase current and speed of the induction motor may oscillate periodically, which will threaten safety and reliability of the system. This paper chooses nine-phase induction motor simulated propulsion system as the research object, small disturbance model of three-phase induction motor is built, and average equivalent model of the converter is built by introducing switch function. On the basis above, small disturbance mathematic model of the whole system is obtained. As for the limitation of parameters adjustment method of restrain low-frequency oscillation, the restrain method combining current close-loop with dead-time compensation is put forward. Finally, the proposed restrain method is verified respectively on the built simulation and experimental analogue platform. And the simulation and experimental results indicate that the proposed method can not only satisfy the requirement of low-frequency oscillation restraining, but also be expanded widely, and the stability of the system can get improved greatly.

Adaptive Output Tracking for Nonlinear Network Control Systems with Time-Delay

The problem of adaptive output tracking is researched for a class of nonlinear network control systems with parameter uncertainties and time-delay. In this paper, a new program is proposed to design a state-feedback controller for this system. For time-delay and parameter uncertainties problems in network control systems, applying the backstepping recursive method, and using Young inequality to process the time-delay term of the systems, a robust adaptive output tracking controller is designed to achieve robust control over a class of nonlinear time-delay network control systems. According to Lyapunov stability theory, Barbalat lemma and Gronwall inequality, it is proved that the designed state feedback controller not only guarantees the state of systems is uniformly bounded, but also ensures the tracking error of the systems converges to a small neighborhood of the origin. Finally, a simulation example for nonlinear network control systems with parameter uncertainties and time-delay is given to illustrate the robust effectiveness of the designed state-feedback controller.

Radiotherapy for small cell lung cancer in current clinical practice guidelines

Several guidelines including radiotherapy recommendations exist worldwide for the treatment of small cell lung cancer(SCLC).To evaluate the differences in radiotherapy recommendations we conducted a systematic review.PubMed and the sites of medical societies were searched for SCLC guidelines published in either English,Chi-nese,or Dutch.This was limited to January 2018 till February 2021 to only include up-to-date recommendations.Data was extracted and compared regarding the guideline’s development method and radiotherapy recommenda-tions.Eleven guidelines were identified(PubMed n=4,societies n=7)from Spain(n=1),Canada(n=1),America(n=3),United Kingdom(n=1),the Netherlands(n=1),and China(n=3),respectively.Nine guidelines assessed the strength of evidence(SOE)and specified the strength of recommendation(SOR),although methods were dif-ferent.The major radiotherapy recommendations are similar although differences exist in thoracic radiotherapy(TRT)dose,time,and volume.Controversial areas are TRT in resected stage I-IIA(pN1),prophylactic cranial irradiation(PCI)in resected as well as unresected stage I-IIA,stereotactic body radiation therapy(SBRT)in un-resected stage I-IIA,PCI time,and PCI versus magnetic resonance imaging(MRI)surveillance in stage IV.The existence of several overlapping guidelines for SCLC treatment indicates that guideline development is(unnec-essarily)repeated by different organizations or societies.Improvement could be made by better international collaboration to avoid duplicating unnecessary work,which would spare a lot of time and resources.Efforts should be made to work together on controversial or unknown fields.