Performance-Based Distributed Control of Multiagent Systems: A Dual Phase Approach.

In this article, we investigate the distributed tracking control problem for networked uncertain nonlinear strict-feedback systems with unknown time-varying gains under a directed interaction topology. A dual phase performance-guaranteed approach is established. In the first phase, a fully distributed robust filter is constructed for each agent to estimate the desired trajectory with prescribed performance such that the control directions of all agents are allowed to be nonidentical. In the second phase, by establishing a novel lemma regarding Nussbaum function, a new adaptive control protocol is developed for each agent based on backstepping technique, which not only steers the output to track the corresponding estimated signal asymptotically with arbitrarily prescribed transient response but also extends the application scope of the proposed control scheme largely since the unknown control gains are allowed to be time-varying and even state-dependent. In such a way, the underlying problem is tackled with the output tracking error converging into an arbitrarily preassigned residual set exhibiting an arbitrarily predefined convergence rate. Besides, all the internal signals are ensured to be semi-globally ultimately uniformly bounded (SGUUB). Finally, two examples are provided to illustrate the effectiveness of the co-designed scheme.

Engineering and Purification of Microcin C7 Variants Resistant to Trypsin and Analysis of Their Biological Activity.

Microcin C7 (McC) as a viable form of antimicrobial has gained substantial attention due to its distinctive antimicrobial activity, by targeting aspartyl tRNA synthetase. McC can be a potential solution against pathogenic microbial infections in the postantibiotic era. However, considering that degradation by digestive enzymes can disrupt the function of this peptide in the gastrointestinal tract, in this study, we attempt to design McC variants to overcome several barriers that may affect its stability and biological activity. The mccA gene encoding the McC peptide precursor was mutated and 12 new McC variants with trypsin resistance were found. The Yej+rimL- strain was used as an indicator to determine the minimum inhibitory concentrations (MICs). The results showed that three variants, including R2A, R2T and R2Q, among 12 variants formed by the replacement of the second arginine of the McC peptide with different amino acids, were resistant to trypsin and had an outstanding antimicrobial ability, with MIC values of 12.5, 25, and 25 µg/mL, respectively. Taken together, our findings show that the engineering of the site-directed mutagenesis of McC significantly enhances McC trypsin resistance and maintains a great antimicrobial activity.

Immunomodulatory Effects of Microcin C7 in Cyclophosphamide-Induced Immunosuppressed Mice.

Microcin C7 (McC) as a viable immunomodulator peptide can be a potential solution for pathogenic microbial infection in the post-antibiotic era and has gained substantial attention. This study was designed to evaluate the immunomodulatory activity of Microcin C7 in a cyclophosphamide (CTX)-induced immunodeficient mouse model. We show that Microcin C7 treatment significantly alleviated the CTX-caused body weight loss, improved the feed and water consumption to improve the state of the mice, and elevated the absolute number and proportion of peripheral blood lymphocytes as well as the level of hemoglobulin. We further aim to characterize the phenotypes of the immune function and intestinal health profiles. The results demonstrate that Microcin C7 treatment increased serum levels of immunoglobulin A (IgA), IgG, interleukin 6, and hemolysin, promoted splenic lymphocyte proliferation induced by concanavalin A and LPS, and enhanced the phagocytosis of peritoneal macrophages immunized by sheep red blood cells. Additionally, Microcin C7 treatment decreased levels of diamine oxidase and d-lactate, ameliorated CTX-induced intestinal morphological damage, and increased the levels of zonula occluden 1, occludin, claudin-1, mucin 2, and secretary IgA in the jejunum and colon. Moreover, Microcin C7 administration is sufficient to reverse CTX-induced intestinal microbiota dysbiosis by increasing the number of Lactobacillus and Bifidobacterium, decreasing the number of Escherichia coli in colonic contents. Collectively, our results demonstrate that Microcin C7 may have protective and immunomodulatory functions and could be a potential candidate used in animal feed, functional foods, and immunological regimens..

Global Consensus Tracking Control for High-Order Nonlinear Multiagent Systems With Prescribed Performance.

In this article, we investigate the prescribed performance tracking control problem for high-order nonlinear multiagent systems (MASs) under directed communication topology and unknown control directions. Different from most existing prescribed performance consensus control methods where certain initial conditions are needed to be satisfied, here the restriction related to the initial conditions is removed and global tracking result irrespective of initial condition is established. Furthermore, output consensus tracking is achieved asymptotically with arbitrarily prescribed transient performance in spite of the directed topology and unknown control directions. Our development benefits from the performance function and prescribed-time observer. Both theoretical analysis and numerical simulation confirm the validity of the developed control scheme.

Effects of Drinking Water Temperature and Flow Rate during Cold Season on Growth Performance, Nutrient Digestibility and Cecum Microflora of Weaned Piglets.

Although water is one of the most important nutrients and is essential for various physiological processes within the body, it does not receive adequate consideration when ensuring optimal nutrition and growth performance in piglets. This study was conducted to investigate the effects of drinking water temperature (DWT) and flow rate (DWF) on growth performance, nutrient digestibility and cecum microflora in weaned piglets during cold weather. Sixty-four piglets with an average body weight of 8.60 ± 0.5 kg were allotted into four groups with four replicates in each group and four pigs in each replicate. The DWT and DWF were set for each group as follows: (1) 13 °C + 300 mL/min, (2) 13 °C + 700 mL/min, (3) 30 °C + 300 mL/min and (4) 30 °C + 700 mL/min, respectively. All groups were fed the same diet during the 28 d trial. The body weight at day 0 and day 29, as well as daily feed intake, were recorded. Diarrhea severity was assessed every day. Fresh fecal samples were collected for four consecutive days at the end of the experiment for the digestibility test. Cecum content was collected after sacrifice for microbial composition analysis. The results indicated that: (1) DWT at 30 °C promoted the average daily gain (ADG) of weaned piglets considerably (p = 0.043) and decreased feed to weight ratio when compared with DWT at 13 °C (p = 0.045). DWF had no substantial effect on the growth performance of piglets (p > 0.05). (2) The 30 °C DWT groups had higher apparent digestibility of crude protein, crude fat and energy than the 13 °C DWT groups (p < 0.05), while DWF had no significant effect on the apparent digestibility of nutrients (p > 0.05). (3) DWT at 30 °C increased the Bacteroidetes abundance and decreased the Proteobacteria abundance in cecum digesta. The change in these two factors may be related to a decrease in diarrhea and the improvement of growth performance. Different DWF had no substantial effect on the cecum microbial structure. To sum up, providing a DWT of 30 °C to weaned piglets in cold weather reduced the abundance of harmful bacteria in the cecum and improved the apparent nutrient digestibility, which is beneficial for maintaining a healthy intestinal microenvironment and promoting growth performance. A lower DWF of 300 mL/min had no adverse effect on growth performance. Therefore, a combination of 30 °C + 300 mL/min is recommended for weaned piglets during cold weather for the consideration of animal welfare and production efficiency.