Hierarchical finite-time cooperative control for teleoperation of networked disturbed mobile manipulators.

This paper investigates the teleoperation problem of networked disturbed mobile manipulators (NDMMs), in which the human operator remotely controls multiple slave mobile manipulators through a master manipulator. Each individual of the slave ones consisted of a nonholonomic mobile platform and a holonomic constrained manipulator that is mounted on the nonholonomic mobile platform. The cooperative control objective of the considered teleoperation problem includes: (1) synchronizing the states of the slave manipulators to the human-controlled master one; (2) forcing the mobile platforms of the slave ones to form a user-defined formation; (3) controlling the geometric center of all the platforms to track a reference trajectory. We present a hierarchical finite-time cooperative control (HFTCC) framework to achieve the cooperative control goal in a finite time. The presented framework includes the distributed estimator, the weight regulator and the adaptive local controller, where the estimator generates the estimated states of the desired formation and trajectory, the regulator selects the slave robot that the master one needs to track, as well as the presented adaptive local controller guarantees the finite-time convergence of the controlled states with model uncertainties and disturbances. Additionally, for improving the telepresence, a novel super twisting observer is presented to reconstruct the interaction force between the salve mobile manipulators and the remote operating environment on the master (i.e., the human) side. Finally, the effectiveness of the proposed control framework is demonstrated by several simulation results.

In vitro evaluation of anticancer nanomedicines based on doxorubicin and amphiphilic Y-shaped copolymers.

Four monomethoxy poly(ethylene glycol)-poly(L-lactide-co-glycolide)(2) (mPEG-P( LA-co-GA)(2)) copolymers were synthesized by ring-opening polymerization of L-lactide and glycolide with double hydroxyl functionalized mPEG (mPEG-(OH)(2)) as macroinitiator and stannous octoate as catalyst. The copolymers self-assembled into nanoscale micellar/vesicular aggregations in phosphate buffer at pH 7.4. Doxorubicin (DOX), an anthracycline anticancer drug, was loaded into the micellar/vesicular nanoparticles, yielding micellar/vesicular nanomedicines. The in vitro release behaviors could be adjusted by content of hydrophobic polyester and pH of the release medium. In vitro cell experiments showed that the intracellular DOX release could be adjusted by content of P(LA-co-GA), and the nanomedicines displayed effective proliferation inhibition against Henrietta Lacks's cells with different culture times. Hemolysis tests indicated that the copolymers were hemocompatible, and the presence of copolymers could reduce the hemolysis ratio of DOX significantly. These results suggested that the novel anticancer nanomedicines based on DOX and amphiphilic Y-shaped copolymers were attractive candidates as tumor tissular and intracellular targeting drug delivery systems in vivo, with enhanced stability during circulation and accelerated drug release at the target sites.

Cellular uptake and cytotoxicity of octahedral rhenium cluster complexes.

Cellular uptake behavior of a novel class of octahedral rhenium cluster compounds, hexahydroxo complexes K(4)[{Re(6)S(8)}(OH)(6)].8H(2)O (1) and K(4)[{Re(6)Se(8)}(OH)(6)].8H(2)O (2), was evaluated in human cervical adenocarcinoma HeLa cells. Confocal microscopy and flow cytometry studies demonstrated that rhenium cluster 1 was not internalized into cell, while rhenium cluster 2 was. Conjugation of a polymer to rhenium cluster 1, namely the derivative K(4)[{Re(6)S(8)}(OH)(5)L] (3) (L is amphiphilic diblock copolymer MPEG550-CH(2)CONH-GlyPheLeuGlyPheLeu-COO(-)), considerably enhanced cellular uptake in a concentration-dependent manner and was predominantly localized in the cytoplasm and nucleus upon incubation time. The uptake of rhenium cluster 2 was mediated by energy-dependent endocytosis, whereas rhenium cluster 3 was directly ingested into cells by cell-fusion-like mechanism. According to the cytotoxicity evaluation test, both rhenium clusters 2 and 3 did not exhibit acute cytotoxic effects up to 50 microM, at the practical concentration level of biological applications. It is, therefore, expected that the rhenium cluster complexes can be promising potential candidates as diagnostic agents for medical treatment.