Quantized controller for a class of uncertain nonlinear systems with dead-zone nonlinearity.

In this paper, a quantized controller is designed for a class of uncertain nonlinear systems subjected to unknown disturbances and unknown dead-zone nonlinearity. A general class of strict feedback nonlinear systems is taken as the plant to design the controller. Here, each differential equation of the system is considered to have unknown parameters and time-varying disturbances. The maximum upper bound of the disturbances is estimated instead of estimating each disturbance. This novel idea reduces the computational cost in handling the disturbances in uncertain systems. The tuning functions are constructed to estimate the unknown system parameter and maximum upper bound of the disturbances. It is considered that the actuator dead-zone nonlinearity is bounded by an unknown parameter and incorporated to design the final quantized controller. A backstepping technique is applied to design the tuning functions and controller that stabilizes the uncertain system. The stability of the proposed controller is proved using the Lyapunov stability based theory. The obtained MATLAB simulation test results verify the designed proposed controller.

Donor-acceptor substituted cyclopropane to butanolide and butenolide natural products: enantiospecific first total synthesis of (+)-hydroxyancepsenolide.

An oxygen substituted donor-acceptor cyclopropane (DAC) is used as a common intermediate in the enantiospecific collective total synthesis of butanolide- and butenolide-based natural products like (+)-juruenolide C and D, (+)-blastmycinone, (+)-antimycinone, and (+)-ancepsenolide. Enantiospecific first total syntheses of (+)-hydroxyancepsenolide and its acetate are achieved confirming their absolute stereochemistry.

Characteristics of long-term cultures of avian primordial germ cells and gonocytes.

Avian cell lines derived from germinal crescent primordial germ cells and gonadal gonocytes with long-term proliferative capacity in vitro and their subsequent rates of colonization and germline transmission are described. In general, male cultures proliferate more rapidly than female cultures although both can be developed into cell lines of >2 × 10(6) cells, at which time, they can be grown indefinitely and a cell bank can be established. All the cell lines injected into embryos transmitted through the germline with the percentage of germline transmission of both male and female cell lines varying from single digits to the high 90s. The derivation of these primordial germ cell and gonadal cell lines and the subsequent robustness of germline transmission validates these cells as suitable for establishment of lines of chickens bearing novel genetic modifications.

Management of complex long bone nonunions using limb reconstruction system.

BACKGROUND: Management of complex nonunions is difficult due to the presence of infection, deformities, shortening and multiple surgeries in the past. Complex nonunions are traditionally managed by Ilizarov fixation. The disadvantages of Ilizarov are poor patient compliance, inconvenience of the frame and difficult frame construction. We conducted a study on 30 long bone complex nonunions treated by the limb reconstruction system (LRS). MATERIALS AND METHODS: Between April 2009 and September 2012, we treated 30 cases of complex nonunion of long bone with the LRS. 28 were male and 2 females. Average shortening was 5.06 cm and 14 cases presented with infected implants. Initially we managed with implant removal, radical debridement followed by fixation with the LRS. In 16 cases, corticotomy and lengthening was done. The average duration of treatment was 9.68 months. We compressed the fracture site at the rate of 0.25 mm per day for 1-2 weeks and distracted the corticotomy at the rate of 1 mm/day till lengthening was achieved. RESULT: The union occurred in 89.28% cases and eradication of infection in 91.66% cases. Average lengthening done was 4.57 cm. We had 79% excellent, 11% good and 10% poor bony result and fnctional result was excellent in 40% cases, good in 50% and failure in 10% cases using ASAMI scoring system. CONCLUSION: LRS is an alternative to the Ilizarov fixation in their management of complex nonunion of long bones. It is less cumbersome to the patient and more surgeon and patient friendly.