Sadahiro Nakajima

Bio: Sadahiro Nakajima is an academic researcher from Hoya Corporation. The author has contributed to research in topics: Laser & Er:YAG laser. The author has an hindex of 6, co-authored 12 publications receiving 949 citations.

Laser surgical unit

Abstract: Apparatus monitors RF return current to maximize the AC signal of impedance at two return electrodes. A transformer with driving and driven windings isolates ESU and patient. At ends of the driving winding are signal and ground terminals joined to the return electrodes with capacitors returning current. An AC coupling capacitor at the signal terminal has a timing circuit in sync to the voltage wave and relative to impedance of the return electrodes. Microprocessing the voltage at the signal terminal of the driving winding watches impedance and determines if the RF return current path is adequate. Voltage detection within the timing circuit has a voltage shaping circuit. A voltage comparator after the voltage detection forms a square wave. A current detection circuit and a coupling capacitor allow AC flow to the driving winding. Current shaping circuit in the current detection circuit has a voltage comparator at the output to form a square wave. Phase detection at the voltage and current detection circuits outputs filters the phase difference that is sampled and held as DC input to a switch, with an output and a few inputs to DC voltages. Phase locking an oscillating voltage source directly and/or through the sample and hold or DC switch tunes oscillation frequency and maximizes the voltage detection circuit output. Monitoring the return current with a signal from the voltage detection circuit connected to an oscillating voltage that is phase locked to the current phase therein shows that no phase difference and maximum signal voltage occur simultaneously.

Medical laser treatment device

Abstract: A medical laser treatment device comprising a laser generation source and a laser handpiece which comprises a light-guiding fiber used to guide a laser beam irradiated from the laser generation source, a probe for guiding the laser beam having been guided by the fiber to an object to be irradiated, at least two independent air supply passages and at least one water supply passage, the laser handpiece being adapted such that the emission end of the light-guiding fiber is airtightly isolated from the incident end of the probe via a light-guiding shield plate to make the internal section of the light-guiding fiber airtight, to cool the emission end of the light-guiding fiber using dry gas supplied from the first air supply passage and to cool the incident end of the probe using gas supplied from the second air supply passage, and being also arranged such that water supplied from the water supply passage is blown out from the peripheral section of the leading end of the probe, thereby preventing the emission end of said light-guiding fiber from absorbing moisture and being heated.

[Effects of Er:YAG laser irradiation on human extracted teeth].

Abstract: The ablation effects of the Erbium:YAG laser (wave length: 2.94 microns) on the human extracted teeth were examined histopathologically. The enamel surface of the human extracted tooth was irradiated by the laser at 500 mJ, 1 pps or 3 pps: 3, 15, 30, 50 and 100 shots. After observation under a dissecting microscope, the teeth were placed in a demineralizing solution of 0.1 M lactate buffer with 6% hydroxyethyl cellulose (pH 4.5) in order to evaluate the acid resistance of the enamel adjacent to the ablated area. After 4 days, the degree of demineralization of the surrounding enamel was assessed by contact microradiography. The result showed that every irradiated tooth had a clear-cut defect, and almost all the teeth had acquired acid resistance at the enamel surrounding the ablated portion. The other experiment was carried out to estimate the effects of the Er:YAG laser through a contact probe. The enamel, dentin and cementum of the extracted teeth were irradiated at 39 mJ or 74 mJ, 10 pps; 10 shots. The teeth were observed under a dissecting microscope. The result clearly indicated that the Er:YAG laser guided by the contact probe could also produce a defect in the dental hard tissue. The above-mentioned findings suggested that the Er:YAG laser could pave the way for the cavity preparation with acid-resistant cavity margin.

Laser treatment device

Abstract: A laser treatment device provided with a laser light source, a laser-light transmitting optical fiber for transmitting laser light output from the laser light source and a probe for guiding the laser light transmitted by the laser-light transmitting optical fiber to an object to be irradiated. Further, the probe is constituted by a laser-light guiding optical fiber separated from the laser-light transmitting optical fiber. Moreover, a cooling chamber for cooling the optical fibers is provided in the neighborhood of an output end of the laser-light transmitting optical fiber, from which the transmitted laser light is output, and an input end of the laser-light guiding optical fiber, from which the laser light output by the laser-light transmitting optical fiber is input to the laser-light guiding optical fiber. Thereby, a medical treatment of a deep part of an affected or diseased region can be achieved without worsening the state of the exit of the laser-light transmitting optical-fiber. Moreover, the output end of the laser-light transmitting optical-fiber can be kept in a favorable condition even after the medical treatment of the deep part of the affected region. Thus there is no obstacle to the next treatment thereof.

Method for increasing heat and shock resistance of phosphate laser glass

Abstract: PURPOSE: To increase the heat and shock resistance, etc. of the titled glass by coating a sol obtained by the hydrolysis and partial condensation of metal alkoxide, etc. on the surface of the phosphate laser glass, and heat-treating to form a vitreous film. CONSTITUTION: An organic metallic compd. such as metal alkoxide (e.g., ethyl silicate and sodium methylate) contg. a metallic element such as Si, B, Na, and Al which is capable of forming glass is dissolved into an organic solvent (e.g., ethyl alcohol and isopropanol). Then an appropriate amt. of water necessary for hydrolysis is added and agitated to carry out the hydrolysis and partial condensation. Then the obtained sol is coated on the surface of phosphate laser glass by immersion, etc., and the coated film is heat-treated to obtain a vitreous film. The heat and shock resistance and the breaking strength of the phosphate laser glass can be increased in this way. COPYRIGHT: (C)1985,JPO&Japio

Surgical Stapling Apparatus

Abstract: A surgical stapling device particularly suited for endoscopic procedures is described The device includes a handle assembly and an elongated body extending distally from the handle assembly The distal end of the elongated body is adapted to engage a disposable loading unit A control rod having a proximal end operatively connected to the handle assembly includes a distal end extending through the elongated body A control rod locking member is provided to prevent movement of the control rod until the disposable loading unit is fully secured to the elongated body of the stapling device

Surgical stapling instrument

Abstract: A surgical stapling instrument (1) comprises a body portion (2, 3), a handle (4) and a staple fastening assembly (8). The staple fastening assembly (8) includes a curved cartridge (10), which comprises at least one curved open row of staples, and a curved anvil (22), which is adapted to cooperate with the cartridge (10) for forming the ends of the staples exiting from the cartridge (10). The staple fastening assembly (8) is adapted to allow unobstructed access towards the concave inner faces of the cartridge (10) and the anvil (22). The cartridge (10) can be moved towards the anvil (22) from a spaced position for positioning tissue therebetween to a closed position for clamping the tissue. Preferably, a knife is contained within the cartridge (10) and is positioned such that there is at least one row of staples on at least one side of the knife.

Display screen or portion thereof with graphical user interface

Abstract: Newness and distinctiveness is claimed in the features of ornamentation as shown inside the broken line circle in the accompanying representation.

Surgical stapling instrument with an articulatable end effector

Abstract: A surgical instrument can comprise a channel configured to support a staple cartridge and, in addition, an anvil pivotable between open and closed positions relative to the channel. The surgical instrument can further comprise a cutting member configured to incise tissue positioned captured between the staple cartridge and the anvil and, in addition, means for stopping the cutting member prior to a distal end datum, wherein the distal end datum can be defined by the distal-most staple cavity in the staple cartridge. In such embodiments, the incision within the tissue may not extend beyond the portion of the tissue that has been stapled.

Articulating surgical stapling instrument incorporating a two-piece e-beam firing mechanism

Abstract: A surgical severing and stapling instrument, suitable for laparoscopic and endoscopic clinical procedures, clamps tissue within an end effector of an elongate channel pivotally opposed by an anvil. An E-beam firing bar moves distally through the clamped end effector to sever tissue and to drive staples on each side of the cut. The E-beam firing bar affirmatively spaces the anvil from the elongate channel to assure properly formed closed staples, especially when an amount of tissue is clamped that is inadequate to space the end effector. In particular, an upper pin of the firing bar longitudinally moves through an anvil slot and a channel slot is captured between a lower cap and a middle pin of the firing bar to assure a minimum spacing. Forming the E-beam from a thickened distal portion and a thinned proximal strip enhances manufacturability and facilitates use in such articulating surgical instruments.