Persistence, extinction and practical exponential stability of impulsive stochastic competition models with varying delays

This paper studies the persistence, extinction and practical exponential stability of impulsive stochastic competition models with time-varying delays. The existence of the global positive solutions is investigated by the relationship between the solutions of the original system and the equivalent system, and the sufficient conditions of system persistence and extinction are given. Moreover, our study shows the following facts: (1) The impulsive perturbation does not affect the practical exponential stability under the condition of bounded pulse intensity. (2) In solving the stability of non-Markovian processes, it can be transformed into solving the stability of Markovian processes by applying Razumikhin inequality. (3) In some cases, a non-Markovian process can produce Markovian effects. Finally, numerical simulations obtained the importance and validity of the theoretical results for the existence of practical exponential stability through the relationship between parameters, pulse intensity and noise intensity

Antibiotic-Induced Disruption of Gut Microbiota Alters Local Metabolomes and Immune Responses

Gut microbiome plays an essential role in modulating host immune responses. However, little is known about the interaction of microbiota, their metabolites and relevant inflammatory responses in the gut. By treating the mice with three different antibiotics (enrofloxacin, vancomycin, and polymixin B sulfate), we aimed to investigate the effects of different antibiotics exposure on gut microbiota, microbial metabolism, inflammation responses in the gut, and most importantly, pinpoint the underlying interactions between them. Although the administration of different antibiotics can lead to different effects on mouse models, the treatment did not affect the average body weight of the mice. A heavier caecum was observed in vancomycin treated mice. Treatment by these three antibiotics significantly up-regulated gene expression of various cytokines in the colon. Enrofloxacin treated mice seemed to have an increased Th1 response in the colon. However, such a difference was not found in mice treated by vancomycin or polymixin B sulfate. Vancomycin treatment induced significant changes in bacterial composition at phylum and family level and decreased richness and diversity at species level. Enrofloxacin treatment only induced changes in composition at family presenting as an increase in Prevotellaceae and Rikenellaceae and a decrease in Bacteroidaceae. However, no significant difference was observed after polymixin B sulfate treatment. When compared with the control group, significant metabolic shift was found in the enrofloxacin and vancomycin treated group. The metabolic changes mainly occurred in Valine, leucine, and isoleucine biosynthesis pathway and beta-Alanine metabolism in enrofloxacin treated group. For vancomycin treatment metabolic changes were mainly found in beta-Alanine metabolism and Alanine, aspartate and glutamate metabolism pathway. Moreover, modifications observed in the microbiota compositions were correlated with the metabolite concentrations. For example, concentration of pentadecanoic acid was positively correlated with richness of Rikenellaceae and Prevotellaceae and negatively correlated with Enterobacteriaceae. This study suggests that the antibiotic-induced changes in gut microbiota might contribute to the inflammation responses through the alternation of metabolic status, providing a novel insight regarding a complex network that integrates the different interactions between gut microbiota, metabolic functions, and immune responses in host

An ultrasound-assisted deposition of NiO nanoparticles on TiO2 nanotube arrays for enhanced photocatalytic activity

An ultrasound-assisted deposition technique was adopted to construct NiO nanoparticles on TiO2 nanotube arrays (NiO-TiO2 NTAs) which were prepared by three-step electrochemical anodization in an ethylene glycol system. The NiO nanoparticles were found to deposit on the surface of the highly oriented TiO2 nanotubes. NiO-TiO2 NTAs exhibited improved photochemical capability under UV irradiation. Compared with TiO 2 NTAs, a more than 2.56-fold enhancement in photocurrent response was achieved using the NiO-TiO2 NTAs. The maximum incident photon to charge carrier generation efficiency (IPCE) values of NiO-TiO2 NTAs and TiO2 NTAs were 83.5% and 22.2%, respectively. The photocatalytic activities of NiO-TiO2 NTAs were evaluated by the photodegradation of methylene blue (MB) aqueous solution. The kinetic constant of photocatalytic degradation of MB using NiO-TiO2 NTAs prepared by ultrasonic deposition for 1.0 h was 1.9 times higher than that using TiO2 NTAs. The enhanced photocurrent response and photocatalytic activity with NiO-TiO 2 NTAs were attributed to the formation of the NiO-TiO2 p-n junctions. ? 2014 the Partner Organisations

Silicon-Encapsulated Hollow Carbon Nanofiber Networks as Binder-Free Anodes for Lithium Ion Battery

Silicon-encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites) were successfully synthesized by dip-coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As-synthesized hollow Si/C composites show excellent electrochemical performance when they are used as binder-free anodes for Li-ion batteries (LIBs). In particular, when the concentration of resol/ethanol solution is 3.0%, the product exhibits a large capacity of 841 mAh g−1 in the first cycle, prominent cycling stability, and good rate capability. The discharge capacity retention of it was ~90%, with 745 mAh g−1 after 50 cycles. The results demonstrate that the hollow Si/C composites are very promising as alternative anode candidates for high-performance LIBs