Observation of self-polarization in BSA protected Au20 clusters.

Bovine serum albumin (BSA)-protected gold clusters (atomicity âˆ¼ 20), prepared using a wet chemical route, show strong dipolar radiative transition with a gap energy of 1.93 eV due to the high oscillator strength, as confirmed by the emission studies. Self-arrangement of the clusters with fixed atomicity yields a low dispersive dielectric and electric self-polarization nature. The electrical hysteresis loop measurements returned a remanent polarization of 0.05 µC cm-2, which can be correlated with the dipolar orientation (activation energy âˆ¼ 45.32 meV), originating from the structure-dependent deformation of the charge density.

Theoretical analysis of magnetically propelled microrobots in the cardiovascular system.

The field of medical microrobotics is rapidly progressing; however, it is particularly challenging to control microrobots inside blood vessels. In this paper, the magnetic propulsion of a microrobot in pulsating flow is investigated. Regarding this task, the advantages of a reduced blood flow velocity are examined. The required magnetic field gradient in relation to the size of the microrobot is theoretically analyzed and compared to that for propulsion during reduced blood flow velocity. Quantitative and qualitative advantages together with the practical challenges are discussed.

Direct observation of back energy transfer in blue phosphorescent materials for organic light emitting diodes by time-resolved optical waveguide spectroscopy.

We demonstrate a high-sensitive transient absorption technique for detection of excited states in an organic thin film by time-resolved optical waveguide spectroscopy. By using a laser beam as a probe light, we detect small change in the transient absorbance which is equivalent to 10-7 absorbance unit in a conventional method. This technique was applied to organic thin films of blue phosphorescent materials for organic light emitting diodes. We directly observed the back energy transfer from emitting guest molecules to conductive host molecules.

Electromagnetic drive of microrobot geometrically constrained in blood vessel.

We propose new electromagnetic actuation of a microrobot by utilizing geometric constraints in a blood vessel. In our concept, a microrobot travels in a vascular network while keeping the contact to the vascular wall. In the paper, forces working on the microrobot are modeled in two dimensions, and conditions to propel the microrobot while pushing it against the vascular wall are described. The design of the microrobot composed of three permanent magnets is also presented. The feasibility of the 2D actuation of the microrobot was confirmed using an experimental setup composed of four pairs of coils generating both uniform magnetic fields and uniform magnetic field gradients. Finally, the model was extended to 3D in order to investigate 3D actuation of the microrobot.

Microsurgical skill assessment: toward skill-based surgical robotic control.

A surgical skill assessment system was developed to quantify microsurgical skills. Infrared optical makers, an inertial measurement unit, and strain gauges were mounted on tweezers to record surgical tasks. In preliminary experiments, the tool tip trajectory, acceleration, and applied force were measured and microsurgery videos were evaluated by three expert surgeons. The preliminary results indicated the feasibility of the system by showing the significant difference between unskilled and skilled surgeons.

Control of fracture reduction robot using force/torque measurement.

We have developed a surgical robotic system for femoral fracture reduction employing indirect traction. Indirect traction in fracture reduction is a generally used surgical method for preventing complications such as bone splits caused by high stress on bones. For traction, a patient's foot is gripped by a jig and pulled to the distal side. Indirect traction has the advantage of distributing bone stress by utilizing a strong traction force; however, this procedure does not accurately control the proper positioning of fractured fragments when a surgical robot is used. The human leg has knee and an ankle joints, and thus robotic motion presents problems in not being able to directly propagate reduction motion to a fractured femoral fragment, rendering control of bone position difficult. We propose a control method for fracture reduction robots using external force/torque measurements of the human leg to achieve precise fracture reduction. Results showed that the proposed method reduced repositioning error from 6.8 mm and 15.9 degrees to 0.7 mm and 5.3 degrees, respectively.

An antimicrotubule agent, TZT-1027, does not induce neuropathologic alterations which are detected after administration of vincristine or paclitaxel in animal models.

One of the major dose-limiting toxicities induced by antimicrotubule antitumor agents such as vinca alkaloids and taxanes is peripheral neuropathy. The neurotoxicity of TZT-1027 (a dolastatin 10 derivative antimicrotubule agent) was thus assessed using the animal models for antimicrotubule agent-induced neurotoxicity. Rabbits were intravenously given TZT-1027 or vincristine weekly for 5 weeks. In the mouse study, TZT-1027, vincristine or paclitaxel was intravenously given every 2 days and/or weekly. Despite the neuropathologic evidence such as myelinated axonal and fiber degeneration in the peripheral nerves and in the sensory tracts of the spinal cord following the treatment with vincristine or paclitaxel, no drug-induced alteration was observed in the TZT-1027 groups. Although there are reports that some other dolastatin derivatives with antimicrotubule activity showed no neurotoxic potential in humans, the present study represents the first demonstration in experimental animals that a dolastatin derivative has no, or at least a lower, neurotoxic potential compared to other antimicrotubule agents.

[Tele-micro-surgery system].

This paper describes a master-slave type tele-micro-surgical system with an intelligent user interface. To enhance the accuracy and the rigidity of the slave-manipulator, multi-circular guides were adopted for the degrees of rotational freedom. To increase the operability of the system, an "anti-shadow" technique was used and the 3D relative information was presented on a 2D display. Furthermore, the anti-shadow was processed using a real-time tracking vision system to guide the slave-manipulator to the target position automatically. Multi-axis force information was converted into auditory information to transmit the reality of the surgical field. It took approximately 25 minutes to suture a 1 mm diameter artificial micro-blood-vessel using the system. The carotid artery of a rat with a diameter of 0.3 mm was also successfully sutured.

Optical switching of a metal-clad waveguide with a ferroelectric liquid crystal.

Optical switching based on waveguide optics with a ferroelectric liquid crystal (FLC) is reported. The FLC cell was prepared as a prism coupler on which the liquid-crystal layer was sandwiched between two gold cladding layers. The role of the gold layer was examined, and the optimum thickness of the top gold layer for obtaining high contrast was determined by use of the Fresnel equation. Various optical modulations of reflectivity were predicted on the basis of theoretical calculation, taking into account the molecular reorientation of the FLC, and examined at an appropriate angle of incidence and rotational angle of the FLC cell with respect to the plane of incidence.