Cephradine drug release using electrospun chitosan nanofibers incorporated with halloysite nanoclay

The chitosan/polyvinyl alcohol/halloysite nanoclay (CS/PVA/HNC) loaded with cephradine drug electrospun nanofibers (NFs) were fabricated and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) techniques. FTIR analysis confirmed the hydrogen bonding between the polymer chain and the developed siloxane linkages. SEM analysis revealed the formation of uniform NFs having beads free and smooth surface with an average diameter in 50–200 nm range. The thermal stability of the NFs was increased by increasing the HNC concentration. The antimicrobial activity was examined against Escherichia coli and staphylococcus strains and the NFs revealed auspicious antimicrobial potential. The drug release was studied at pH 7.4 (in PBS) at 37 °C. The drug release analysis showed that 90% of the drug was released from NFs in 2 h and 40 min. Hence, the prepared NFs could be used as a potential drug carrier and release in a control manner for biomedical application.

Finite-time stabilization of port-controlled Hamiltonian systems with nonvanishing disturbances

This paper concerns the problem of finite-time stabilization of nonlinear port-controlled Hamiltonian systems subject to nonvanishing disturbances via a composite control manner. The composite controller is developed by combining the damping injection, the finite-time feedback control and the finite-time disturbance observer techniques. The key idea is that a finite-time disturbance observer is designed to estimate disturbances and the estimation of disturbances is employed to feedforward compensate the disturbances. Finite-time stability analysis for the augmented system is presented. An example of a nonlinear circuit system with simulation results demonstrates the effectiveness of the proposed method.

Design of 80000N·m Torsion Testing Machine

The article introduce the mechanical structure and the principles of 80000 N·m torsion testing machine, the structure and the principles of checking power unit of this kind of testing machines and the control manner and the principles of the electronic control system, than expound the benefits of the equipment and its application.

Simulation and Analyzing of Mechanical Smoke Exhaust in a High-Rise Building

The mechanical smoke exhaust is as acknowledged as an effective smoke control manner by making use of some necessary exhaust facilities. In this paper, a field model with a combination of a zone model were used to simulate the mechanical smoke exhaust in a loop corridor of the fire floor in a high-rise hotel, for the propose of evaluate fire safety of mechanical smoke exhaust. There were several factors are under discussion, as the arrangement of smoke vents, quantity of smoke vents, the volume of smoke exhaust, the position of the smoke vents and height of ceiling indoor, et al. The conclusions were obtained as followed. When two exhaust vents were set symmetrically in the loop corridor, one of which was located nearby the fire room, the smoke exhausted better. The volume of smoke exhaust per unit area with 60m3/h according to regulations, always could ensure safety of smoke exhaust.

Tripod-Type Piezoelectric Traveling Mechanism for Miniature Robot

A new piezoelectric in-plane traveling mechanism of miniature robot was proposed. It seems like a small tripod-type device and runs on stick-slip principle. There were three actuators acted as feet in the traveling mechanism. They were driven separately and controlled through a microcontroller unit to realize varied motion. Theoretically, the mechanism could revolve around any axis and translate along any direction under the appropriate control manner. Therefore, it was desired to serve as locomotive units for miniature robot, which perform various precise positioning tasks such as micromachining, micro-assembly etc.

Study on Electrospark Depositing & Welding Power Supply

The requirements of the power supply design are proposed based on the principle of discharge process in depositing & welding power supply, and a depositing & welding power system schematic is designed according to the requirements. The control manner of the power supply combines RLC (Resistance-Inductance-Capacitance) circuit with fast SCR, and the deposition and restoration can be achieved by using the NE555 circuit to trigger the fast silicon controlled rectifier. Furthermore, parameters such as voltage, capacitance, frequency, motion mode of electrode are probed into, a depositing & welding test is experimented and the waveform of the power supply are analyzed. According to the results of experiments and analysis, it is clear that the output of the power supply can meet the requirements of working successfully and achieve the required standard to do electrospark depositing and welding operations. However, the actual working electrospark frequency is lower than the trigger pulse frequency added on the fast SCR, which result in a lower efficiency in depositing & welding work. Main reasons for this situation is that the relative movement of the electrode and the work-piece can’ t guarantee the best conditions for electrospark and the fast SCR in circuit can’t be reliably turn-off fast. These research laid foundations for further electrospark depositing & welding power supply design and efficiency improvement.