Coaxial Alignment Research Articles

Laser angioplasty: controlled delivery of argon laser energy.

A laser catheter system that integrates balloon and fiberoptic technologies was evaluated. In vitro tissue studies were conducted to compare the tissue response to laser irradiation from a bare optical fiber (undiverged light beam) and from a fiber with an optical assembly (diverged light beam). An in vivo study of occluded and unoccluded canine femoral arteries examined coaxial alignment of the diverged light beam and the resultant thermal effects. In the in vitro studies, a diverged laser light beam effected maximum tissue ablation (mean crater diameter, 1.81 mm +/- 0.44) at a distance of only 3 mm from the optical fiber tip. The in vivo study demonstrated the ability of a specially designed balloon catheter to align the diverged laser beam coaxially within the arterial lumen. This laser catheter system successfully avoids the risks of inadequate tissue removal and perforation.

Steerable fiberoptic catheter delivery of laser energy in atherosclerotic rabbits

Imprecision in guiding and positioning is a recurring problem with fiberoptic delivery of laser energy (E) in small arteries. Manipulation can produce mechanical perforation of the vessel, and noncoaxial alignment can result in thermal perforation at relatively low laser energy levels. A No. 4.5 French single-lumen catheter was designed to accommodate both a steerable guidewire and an optical fiber. It was passed, under fluoroscopic control, into the abdominal aorta in 18 atherosclerotic rabbits. Argon laser energy was delivered coaxially at three sites in each of 14 rabbits (total = 42 sites); four rabbits were controls. Laser power levels (1 to 6 W) and exposure times (20 to 60 seconds) were varied. Energy level in joules (J) was calculated for each exposure. Saline flush at 25 ml/min was delivered through the catheter during laser exposures. Angiographic or microscopic evidence of vessel perforation was observed at 10 sites (E = 174 ± 108 J). Another six sites exhibited microscopic laser effect only, without evidence of vessel perforation (E = 155 ± 91 J). The remaining 26 sites exhibited no effects of laser energy (E = 117 ± 92 J). No angiographically visible perforation occurred with E < 120 J. This study suggests that a fiberoptic catheter with steerable guidewire allows safer intravascular manipulation of optical fibers, improves coaxial alignment in the arterial lumen, and may permit substantial laser energy delivery into atherosclerotic arteries.

Inclusion Complexation of Prostaglandin F2α with γ-Cyclodextrin in Solution and Solid Phases

A solid complex of prostaglandin F2α (dinoprost) with γ-cyclodextrin in a molar ratio of 1:1 was obtained on the basis of the Bs-type phase solubility diagram. The mode of interaction in the solid state was studied by powder X-ray diffractometry, thermal analysis, and carbon-13 cross polarization/magic angle spinning nuclear magnetic resonance (13C-CP/MAS-NMR) spectrometry. The X-ray diffraction and NMR data suggested that prostaglandin F2α is included in the cylindrical channels formed by coaxial alignment of γ-cyclodextrin molecules to give a channel type structure. Dissolution and thermal behaviors of the prostaglandin F2α-γ-cyclodextrin complex were examined and compared with the drug itself. The result indicated that the γ-cyclodextrin complex may have great utility as a rapidly dissolving form of prostaglandin F2α with improved thermal stability.

Magnetic Field for Radiating and Receiving Loops Placed on Parallel Planes

In the calibration of radio receivers and field-intensity meters, a radiating loop and a receiving loop under test are mainly located either in a coaxial or coplane to each other. A formula to obtain the average magnetic-field strength incident on a receiving loop is derived for the case where the radiating and receiving loop antennas have a certain deviation on a parallel plane from the coaxial or coplanar alignment of the loops. In order to expand the uniform region of the magnetic field around the test point, the distribution of the magnetic field is investigated by using this formula for some alignments where the four (or less) radiating loops and a receiving loop lie on parallel planes to each other. It is obvious that the uniform regions are improved by factors of about 10 or 16 by increasing a radiating loop to two or four loops, respectively.

Support arrangement for a flexible sound generating diaphragm

A support arrangement for readily mounting the diaphragm of a piezoelectric transducer on a desired node ring, the diaphragm having coaxially mounted thereon a circular piezoceramic element having a diameter substantially the same as that of the node ring. A substantially rigid support member and a clamping spider have annular means thereon also having the same diameter as that of the node ring such that the periphery of the piezoceramic element acts as a guide means by cooperating with one of the annular mounting means to assure coaxial alignment of the diaphragm, the support members, and the clamping spider. The support members and the clamping spider are snapped together to rapidly and accurately provide the diaphragm mounting on the desired node ring.

Dynamic loudspeaker having magnetic assembly adhesively bonded within a surrounding basket

A loudspeaker is constructed by circumferentially bonding a magnetic assembly in coaxial alignment rearward within a frame and installing an acoustic radiator assembly at a forward end of the frame, the acoustic radiator assembly having a cylindrical member about which a voice coil is wound, the cylindrical member extending rearward into an annular flux gap in the magnetic assembly such that the voice coil is disposed in proper alignment within the annular flux gap by virtue of the cylindrical member bearing against a mating surface of the magnetic assembly, thereby bringing the acoustic radiator assembly into substantially coaxial alignment with respect to the frame to facilitate suspension thereof at the forward end of the frame.

Modified Soil Strain Gage

While it appears that the greatest effort regarding in-situ monitoring of soils has been directed as stress measurements, strain monitoring is of equal importance. The reason for the past emphasis on stress measurement is obviously due to inherent difficulties associated with strain measurements in a discrete particulate mass such as soil. Recently, however, a new technique for soil strain measurement has appeared and has resulted in a commercially available system marketed by Bison Instruments, Inc., of Minneapolis, Minn. The procedure utilizes a pair of sensors that are disk-shaped coils placed free floating in the soil in parallel and coaxial alignment. The separation distance between the coils is sensed by their mutual inductance. An inductance bride produces a voltage that varies as a function of strain, since a change in spacing of the coils from the initial value produces a bridge unbalance. An external instrument package contains the necessary driving, amplification, balancing, readout, calibration controls, and a self-contained power supply.

Transcervical tubal occlusion with a steerable hysteroscope: Implantation of devices into extirpated human uteri

A new steerable fiberoptic hysteroscope particularly useful in visualizing the tubal ostia has been evaluated in 61 extirpated uteri. The efficacy and safety of this hysteroscope were shown. The feasibility of deploying occlusive devices into the intramural portion of the tubes with the steerable hysteroscope was demonstrated. Whether these devices or modifications thereof will prove to be superior to other currently tested methods of occlusion, e.g., caustics, plastics, or cautery under in vivo conditions, remains to be established. The steerability of the hysteroscope has advantage irrespective of the method to achieve transcervical tubal occlusion as it allows coaxial alignment of the delivery.

Coaxial Alignment of Laser Beams for Perturbation Experiments

An instrument is described for the coaxial alignment of two laser beams, one of which is a continuous wave helium-neon laser, the other one a pulsed neodynium glass laser. The helium-neon laser beam is aligned such that it propagates in the axis of the pulsed laser beam and thus permits observation of changes before, during, and after the occurrence of the pulsed laser event. Although the design emphasized the 1.35-mu sidebands of the neodymium laser, most tests were conducted at 1.06 mu, where neodymium in glass ordinarily operates. A residual nonlinearly polarized component of the pulsed laser light caused considerable disturbance in the detection circuit and prevented low level detection of perturbation effects.

Complexes of Starchy Materials with Organic Compounds

The crystal structure of γ-cyclodextrin complexes with several organic compounds have been investigated by X-ray powder method. A two-dimensional tetragonal unit cell having a=b=27.2Å and a two-dimensional hexagonal unit cell having a=b=32.7Å, were reasonably proposed for hydrated and anhydrous γ-dextrin complexes, respectively. The change of the crystal structure caused by dehydration seemed to be resulted from the change of the packing arrangement of circular cylinders that are made by coaxial alignment of the dextrin molecules. Results obtained were tentatively applied to consider the 81-helical configuration of amylose.

Large Size Non-Rotating High-Intensity Carbons and Their Application to Motion Picture Projection&lt;!--&lt;xref ref-type="other" rid="fn1-10.5594_J10092"&gt;*&lt;/xref&gt;--&gt;

The high-intensity, direct-current arc between small, copper-coated carbons operated in coaxial alignment without rotation with a reflector optical system has achieved a widespread and growing popularity over the past few years for theatrical projection of motion pictures. This type of light-source has now been extended to include larger carbons and higher currents. These larger carbons of this type with the proper optical system will give substantially higher light on the motion picture screen. — Fundamental facts about the arc behavior and the conditions necessary to obtain stable and steady operation with these larger carbons are described. The correlation of the luminous characteristics of the arc with the optical system is reviewed. The performance of a new arc with a suitable optical system is given from the standpoint of offering possibilities for projection. Carbon consumption rates, arc current and voltage, and light on the screen are discussed.