Approximate optimal and safe coordination of nonlinear second-order multirobot systems with model uncertainties.

This paper investigates the approximate optimal coordination for nonlinear uncertain second-order multi-robot systems with guaranteed safety (collision avoidance) Through constructing novel local error signals, the collision-free control objective is formulated into an coordination optimization problem for nominal multi-robot systems. Based on approximate dynamic programming technique, the optimal value functions and control policies are learned by simplified critic-only neural networks (NNs). Then, the approximated optimal controllers are redesigned using adaptive law to handle the effects of robots' uncertain dynamics. It is shown that the NN weights estimation errors are uniformly ultimately bounded under proper conditions, and safe coordination of multiple robots can be achieved regardless of model uncertainties. Numerical simulations finally illustrate the effectiveness of the proposed controller.

Robust Near-Optimal Coordination in Uncertain Multiagent Networks With Motion Constraints.

This article addresses the robust coordination problem for nonlinear uncertain second-order multiagent networks with motion constraints, including velocity saturation and collision avoidance. A single-critic neural network-based approximate dynamic programming approach and exact estimation of unknown dynamics are employed to learn online the optimal value function and controller. By incorporating avoidance penalties into tracking variable, constructing a novel value function, and designing of suitable learning algorithms, multiagent coordination and collision avoidance are achieved simultaneously. We show that the developed feedback-based coordination strategy guarantees uniformly ultimately bounded convergence of the closed-loop dynamical stability and all underlying motion constraints are always strictly obeyed. The effectiveness of the proposed collision-free coordination law is finally illustrated using numerical simulations.

Parametric Neural Network-Based Model Free Adaptive Tracking Control Method and Its Application to AFS/DYC System.

This paper deals with adaptive nonlinear identification and trajectory tracking problem for model free nonlinear systems via parametric neural network (PNN). Firstly, a more effective PNN identifier is developed to obtain the unknown system dynamics, where a parameter error driven updating law is synthesized to ensure good identification performance in terms of accuracy and rapidity. Then, an adaptive tracking controller consisting of a feedback control term to compensate the identified nonlinearity and a sliding model control term to deal with the modeling error is established. The Lyapunov approach is synthesized to ensure the convergence characteristics of the overall closed-loop system composed of the PNN identifier and the adaptive tracking controller. Simulation results for an AFS/DYC system are presented to confirm the validity of the proposed approach.

An electrochemical immunosensor based on reduced graphene oxide/multiwalled carbon nanotubes/thionine/gold nanoparticle nanocomposites for the sensitive testing of follicle-stimulating hormone.

Follicle-Stimulating Hormone (FSH) is a kind of gonadotropin which can promote human reproduction and development. Abnormal FSH levels may lead to endocrine disorders and infertility. Sensitive determination of FSH is very significant for the clinical diagnosis of these diseases. Here, an electrochemical immunosensor based on a screen-printed electrode (SPE) was developed for the detection of FSH. Nanocomposites, compounded with reduced graphene oxide (rGO), multiwalled carbon nanotubes (MWCNTs), thionine (Thi) and gold nanoparticles (AuNPs), were used for increasing the specific surface area to adsorb molecules and amplify signals. The rGO/MWCNTs/Thi/AuNP nanocomposites, anti-FSH and BSA were successively assembled onto a SPE to fabricate the immunosensor. Electrochemical performance of the modified immunosensor was studied by differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). FSH testing was based on the principle that the insulating FSH antigen-antibody immunocomplex could retard the electron transfer of Thi which led to the decrease of the DPV current response. Under optimum conditions, the rGO/MWCNTs/Thi/AuNP modified immunosensor exhibited high sensitivity and accuracy for the determination of FSH in a linear range from 1 mIU mL-1 to 250 mIU mL-1, and the detection limit was 0.05 mIU mL-1 at a signal-to-noise ratio of 3. The immunosensor was successfully applied for the determination of quality serum samples with a recovery of 94.0-109.8%. The electrochemical immunosensor could be utilized for testing other gonadotropins.

Most Adult Intussusceptions are Caused by Tumors: A Single-Centre Analysis.

BACKGROUND: Adult intussusception is less common than paediatric intussusception. The aim of this study was to explore the clinical presentation, aetiology, diagnosis and treatment of adult intussusception. METHODS: Adults (>18 years) with intussusception treated by surgical or conservative measures were included from January 2005 to January 2018, and the manifestation, types, diagnosis and treatment of adult intussusception in our centre were reviewed. RESULTS: A total of 150 patients with adult intussusception were included in this study. The clinical manifestations included 111 cases (74%) of abdominal pain, 38 cases (25.3%) of bloody stool, 37 cases (24.7%) of bowel obstructions, 33 cases (22%) of abdominal distension, 29 cases (19.3%) of nausea and vomiting, 19 cases (12.7%) of an abdominal mass, and 12 cases (8.0%) of diarrhoea. The types of intussusception were classified into 36 cases (24%) of enteric intussusception, 87 cases (58%) of intestine-colon intussusception and 27 cases (18%) of colonic intussusception. Surgical intervention was applied in 139 cases (92.7%), including 115 patients who underwent open surgery, and laparoscopy-assisted surgery was performed in 24 patients. The main pathogenesis of intussusception was malignant tumors in 51 cases (36.7%) and benign tumors and polyps in 49 cases (35.3%). CONCLUSION: Malignant and benign tumors are the main causes of adult intussusception. Abdominal CT is the preferred evaluation method for the preoperative diagnosis of this condition. The choice of surgical procedure depends on the location and type of intussusception.

Experimental Study on the Permeability of SAP Modified Concrete.

To study the permeability of superabsorbent polymer (SAP) modified concrete and the effect of internal pore characteristics on the permeability of concrete specimens, the results of the water penetration under pressure test, the mercury intrusion porosimetry (MIP) test, and scanning electron microscopy (SEM) of SAP concrete were obtained and analyzed. The research shows that the addition of an appropriate amount of SAP can effectively improve the anti-permeability performance of concrete. After adding 0.2~0.6% SAP of cement quality to concrete, the penetration height value was reduced by 35~45%, the porosity was increased by 21-95%, and the tortuosity is increased by 14-15%, and all indicators show regular changes with the increase in SAP usage. Adding SAP to concrete changes the internal connection state of concrete, thereby further improving its impermeability by reducing the capillary pressure and changing the shape of the pores. The liquid permeation resistance is increased by the "threshold effect" inside concrete; this "threshold effect" is caused by the addition of SAP.

Integrated metabonomic-proteomic analysis reveals the effect of glucose stress on metabolic adaptation of Lactococcus lactis ssp. lactis CICC23200.

A combined proteomic and metabonomic approach was used to investigate the metabolism of Lactococcus lactis ssp. lactis subjected to glucose stress treatment. A proteomic method was used to determine 1,427 altered proteins, including 278 proteins with increased expression and 255 proteins with decreased expression. A metabonomic approach was adopted to identify 98 altered metabolites, including 62 metabolites with increased expression and 26 metabolites with decreased expression. The integrated analysis indicated that the RNA and DNA mismatch repair process and energy metabolism were enhanced in response to high-glucose stress in L. lactis. Lactococcus lactis responded to glucose stress by up-regulating oxidoreductase activity, which acted on glycosyl bonds, hydrolase activity, and organic acid transmembrane transporter activity. This led to an improvement in the metabolic flux from glucose to pyruvate, lactate, acetate, and maltose. Down-regulation of amino acid transmembrane transporter, aminoacyl-transfer RNA ligase, hydroxymethyl-, formyl-, and related transferase activities resulted in a decrease in the nitrogen metabolism-associated metabolic pathway, which might be related to inhibition of the production of biogenic amines. Overall, we highlight the response of metabolism to glucose stress and provide potential possibilities for the reduced formation of biogenic amines in improved level of sugar in the dairy fermentation industry. Moreover, according to the demand for industrial production, sugar concentration in fermented foods should be higher, or lower, than a set value that is dependent on bacterial strain and biogenic amine yield.

Preoperative Plasma Fibrinogen and Serum Albumin Score Is an Independent Prognostic Factor for Resectable Stage II-III Gastric Cancer.

BACKGROUND: Radical gastrectomy with D2 lymphadenectomy is recognized as the standard treatment for resectable advanced gastric cancer. Preoperative fibrinogen and albumin measurements may bring clinical benefits in terms of providing advanced notice of a poor prognosis or recurrence in patients undergoing radical resection. The aim of this study was to identify markers that are predictive of a poor prognosis prior to surgery. METHODS: Eight hundred forty-two consecutive patients who underwent curative radical gastrectomy at our hospital between 2008 and 2012 were retrospectively reviewed. Based on plasma fibrinogen and serum albumin levels, preoperative fibrinogen and albumin scores (Fib-Alb scores) were investigated, and the prognostic significance was determined. RESULTS: The patients were classified according to a Fib-Alb score of 0 (n = 376), 1 (n = 327), or 2 (n = 139). When the correlation between the response rate and the change in the Fib-Alb score was investigated, the response rate was significantly lower in patients with an increased Fib-Alb score than in the other patients. In the survival analysis, patients in the Fib-Alb high-score group exhibited significantly worse recurrence-free survival (RFS) (P = 0.030) than patients in the other groups. A multivariate analysis using clinical stage and the change in the Fib-Alb score as covariates revealed that a change in the Fib-Alb score (Fib-Alb score 1, HR: 1.31, 95% CI: 1.03-1.66, P = 0.028; Fib-Alb score 2, HR: 1.61, 95% CI: 1.20-2.17, P = 0.001) was a significant independent predictive factor for RFS. CONCLUSIONS: The prognosis of patients with high fibrinogen and low albumin levels is poor. The Fib-Alb score was shown to be an independent prognostic factor for postoperative recurrence in gastric cancer patients who underwent radical gastrectomy.

A paper-based electrochemical immunosensor with reduced graphene oxide/thionine/gold nanoparticles nanocomposites modification for the detection of cancer antigen 125.

A paper-based electrochemical immunosensor was developed for the detection of cancer antigen 125 (CA125) by screen-printing technique. The reduced graphene oxide/thionine/gold nanoparticles (rGO/Thi/AuNPs) nanocomposites were compounded and coated onto the working electrode of immunosensor for CA125 antibody (anti-CA125) immobilization and detection signal amplification. The detection principle was based on the fact that the immunocomplex formed by specify binding of CA125 antibody and antigen could reduce the current response of thionine, which was proportional to the corresponding concentration of CA125 antigen. The immunoassay results showed that the linear range of CA125 was from 0.1 U mL-1 to 200 U mL-1 with the limit of detection (LOD) of 0.01 U mL-1 at signal to noise of 3. Quality control serum samples measured by our proposed immunosensor showed acceptable agreement with traditional ELISA method with the relative error less than 8.05%. The immunosensor exhibited good electrochemical performance with high reproducibility, reliability, stability and accuracy. The proposed immunosensor could be used for the determination of CA125 and had the potential for point-of-care testing (POCT) of other tumor marker.