Teflon-coated Wire Research Articles

Measurements of the chemical composition of cloudwater at a clean air site in central Scandinavia<sup>1</sup>

A total of 179 samples of cloudwater were obtained during the summers of 1983 and 1984 at a clean-air site in the mountains of central Scandinavia. Impaction of droplets on teflon-coated wires provided samples with a time resolution of 5-30 min. Supporting data include cloud liquid water content, rainwater composition, aerosol number concentration, wind speed and direction, and 48-h isobaric trajectories. Collected samples were analyzed for pH. Na + , K + , Mg 2+ . ,Ca +2 NH + 4 , CI - , NO - 3 , and SO 2 4 . A wide range of concentrations were encountered, with, for example. sulfate concentrations ranging from 1 to 1600 μeq 1 -1 . Transport of air from remote regions (north Atlantic Ocean, Arctic) is shown to be associated with the very low concentrations. while the high concentrations occurred in conjunction with transport from industrial regions in Europe. Median clean-air concentrations in Arctic air. calculated from cloudwater composition and liquid water content, were 3 pptv ammonia (gas and aerosol combined). 6 pptv nitrate (gas and aerosol), and 30 ng m -3 sulfate. DOI: 10.1111/j.1600-0889.1986.tb00186.x

Ventrolateral medullary surface blood flow determined by hydrogen clearance.

The H2 clearance technique was used to determine the blood flow of the postulated respiratory chemosensitive areas near the ventrolateral surface of the medulla. In 12 pentobarbital sodium-anesthetized cats, flow (mean +/- SD) was measured from 25-micron Teflon-coated platinum wire electrodes implanted to a depth of 0.3-0.7 mm. Flow (in ml X min-1 X 100 g-1, n = 35) was 52.8 +/- 28.5 in hypocapnia [arterial CO2 partial pressure (PaCO2) = 21.8 +/- 1.6 Torr], 57.8 +/- 27.5 in normocapnia (PaCO2 = 31.9 +/- 2.2 Torr), and 75.0 +/- 31.7 in hypercapnia (PaCO2 = 44.5 +/- 3.0 Torr). Flow determined from 15 electrodes in adjacent pyramidal tracts (white matter) was less at all levels of CO2; 22.9 +/- 12.3 in hypocapnia, 29.1 +/- 15.9 in normocapnia, and 33.9 +/- 13.9 in hypercapnia. In hypoxia [arterial O2 partial pressure (PaO2) = 39.9 +/- 6.3 Torr] ventrolateral surface flow rose to 87.9 +/- 47.6, and adjacent white matter flow was 35.8 +/- 15.6. These results indicate that flow in the postulated central chemoreceptor areas exceeds that of white matter and is sensitive to variations in PaCO2 and PaO2.

A simple method for fashioning small diameter concentric bipolar electrodes for stimulation of nervous tissues

A simple method for fashioning small diameter concentric bipolar stimulating electrodes by sputtering gold over Teflon-coated wire is described.

Strain measurements in floating ice platforms and their application to platform design

The use of the natural ice cover in the Canadian high arctic for offshore petroleum exploration has made possible the drilling of 10 exploratory wells at very reasonable cost. The natural ice is thickened in the loaded area by flooding and freezing in thin layers and required ice thicknesses are obtained using theory for laterally loaded elastic, homogenous plates on elastic foundations. The suitability of this type of theory, which assumes linear strain distribution through the section and a neutral axis at the middle plane, has been questioned, especially since the ice behaves as a visco–elastic material and creeps or strains with time.Resistance strain gauges made of 3 m long, 0.127 mm diameter Teflon-coated wire have been used the last two winters to measure strains in the ice platforms. They have worked well and during the winter and spring of 1978 strains at five different levels in an ice platform beneath the heavier loads were measured and recorded continuously for 62 days. Strain profiles were linear with the neutral axis 0.4 m above the middle plane of the 7.1 m thick platform. Maximum measured principal strains were 1300 με and maximum extrapolated extreme fibre strains were 2100 με, confirming that the strains are small. Stress and effective elastic modulus values are shown to decrease rapidly in the early stages of loading.

Guide wire thrombogenicity measured by fibrinopeptide A radioimmunoassay

A radioimmunoassay for measurement of canine fibrinopeptide A, which provides a quantitative index of thrombin action on canine fibrinogen, was applied to measurements of the thrombogenicity of angiographic guide wires. Benzalkonium-heparin-treated Teflon-coated, untreated Teflon-coated, and uncoated stainless steel wires were compared in an experiment in dogs which closely simulated the use of these wires in humans. During the first 4 min after insertion, the benzalkonium-heparin-treated Teflon-coated wire was associated with significantly greater systemic levels of fibrinopeptide A than were either Teflon-coated or stainless steel wires. Beyond 10 min, markedly increased levels of fibrinopeptide A were measured in association with these latter two wires compared to the benzalkonium-heparin-treated Teflon-coated wire. Both the early rises in fibrinopeptide A associated with the benzalkonium-heparin-treated Teflon-coated wire and the late increases in fibrinopeptide A associated with the Teflon-coated and uncoated stainless steel wires could be eliminated by prior systemic administration of low dose heparin (40U/kg). These studies suggest that, at least in regard to activation of the plasma clotting system, the benzalkonium-heparin treatment offered no advantages over the other wires tested in terms of reduced thrombogenicity within the critical 10 min following insertion. No difference could be discerned between uncoated stainless steel wires and Teflon-coated stainless steel guide wires in this test.

Correlation between intraluminal pressure of the oviduct and the electrical activity of the longitudinal peritoneal muscle in the rabbit.

Correlations between the intraluminal pressure of the oviduct isthmu s and the electrical activity of the longitudinal peritoneal muscle surrounding the oviduct were studied in vivo in the rabbit. The electrical activity of the longitudinal peritoneal muscle was measured by implanted teflon-coated wire electrodes and the intraluminal pressure was measured by balloon-tipped catheters. A correlation between the spikes of electrical activity recorded in the peritoneal muscle and bursts of increased liminal pressure was found. The results suggest that the spontaneous increases in intraluminal pressure is the result of contractions of the longitudinal peritoneal muscle rather than the result of oviductal contractions in themselves.

Thrombogenicity of guide wires

Three patients undergoing retrograde left ventricular catheterization experienced cerebral emboli with catastrophic neurologic consequences. In each instance, a Teflon-coated guide wire was used to facilitate passage through the aortic valve. This finding led to a detailed investigation of the procedures and materials used. The thrombogenicity of both Teflon and stainless steel guide wires was determined in 10 mongrel dogs. Clot formation was readily identified within a few minutes on all guide wires. In each instance clotting was significantly less on steel than on Teflon-coated wires ( P Although our experiments may not be directly applicable to man, we recommend that the increased thrombogenicity of Teflon-coated wires be considered, When such wires are needed, they should be used with caution and preferably only in the descending aorta for brief periods, or in conjunction with systemic hepatization.

A Corona-Discharge Method of Producing Shrink-Resistant Wool and Mohair

A pilot-scale corona reactor that produces a high-power corona for rapid treatment of wool or mohair top was built and tested. The maximum production rate is 43 lb/hr for a 2-sec. treatment. Power consumption of the 14×24-in. corona cell is 4.5 kw at 16,150 v-2070 Hz but is greatly reduced with fractional reductions in voltage. During operation, electrode temperature is controlled by circulating thermostatted air over the back of the electrodes, which have heat-dissipating fins. Control of the corona-field atmosphere permits treatment over a wide range of humidity and chlorine con centration. The web is transported by either a single Teflon-coated wire belt or a double belt system consisting of a wire belt and a Teflon-impregnated fiberglass belt, the choice depending on processing conditions and type of fiber. Operating characteristics of the reactor are described, as well as the improvement in shrinkage resistance and spin nability that corona treatment imparts to wool and mohair.

Catheter tip deflector system for selective bronchography.

Percutaneous transcricothyroid membrane catheterization of the bronchial tree for bronchographic examination is simple and safe (5). For entrance into small subsegmental branches, catheters of various curvatures are required. It is often necessary to exchange various preshaped catheters when studying several subsegmental branches, thus prolonging the procedure and increasing the possibility of complications. The use of a catheter tip deflector system obviates the need for such substitution. Following the introduction of guides for angiography (4, 6), application of these technics for controlling catheters in bronchography was suggested (7). The use of a catheter tip deflector system2 is ideally suited for regulating and varying the curvature of any catheter following its percutaneous introduction through the cricothyroid membrane. The system consists of a tip-deflector handle and a short (35 cm) Teflon-coated wire (O.D. 1.14 mm). The tip-deflecting guide wire allows controlled curvature from 0 to 180° and has excellent rotational torque control. A soft, pliable, thin-walled polyethylene catheter material is used (6.3–7.1 F).2 Larger sizes might be employed for bronchial brushing technics. Technic Preoperative medication for the average patient includes codeine 1 gr, Benadryl 50 mg, and atropine 1/120 gr intramuscularly, one-half hour prior to the examination. Breakfast or lunch is withheld, depending upon the time of the examination. The procedure is carried out with aseptic technic and with the patient in the upright position. The skin is prepared with tincture of quaternary ammonium antiseptic 1:500. The skin over the cricothyroid membrane is infiltrated with 1 ml of 2 per cent lidocaine, using a 25-gauge needle. The cricothyroid membrane is punctured with a 21-gauge needle, and 2 ml of lidocaine is instilled into the trachea. A 3-mm stab wound is made in the skin overlying the cricothyroid membrane with a No. 11 Bard Parker blade (Fig. 1, A). A 16-gauge 11/2-inch thin-walled needle with a 50° curve2 is employed to puncture the cricothyroid membrane (Fig. 1, B). Puncture is facilitated by grasping the larynx firmly between the thumb and forefinger of the left hand and using gentle pressure to insert the curved tracheal needle. The needle is inserted as far as the hub, and air is withdrawn to ensure that the tip is free in the lumen of the trachea. An additional 2 ml of 2 per cent lidocaine is now instilled into the trachea. While the hub of the needle is held in the left hand, the soft end of the guide wire (60 cm fixed core, O.D. 0.889 mm, Teflon-coated) is inserted through the needle into the trachea for a distance of approximately 10 cm (Fig. 1, C). The curved tracheal needle is then withdrawn over the guide wire with the right hand, and the wire is kept in place with the thumb and forefinger of the left hand (Fig. 1, D).

Central-venous-pressure monitoring. Localization of a catheter with teflon wire.

SAFETY and accuracy in central-venous-pressure monitoring require accurate placement of the catheter tip in or near the superior vena cava. This can be accomplished in any hospital that owns a 1-channel electrocardiogram. A teflon-coated wire is placed inside a catheter so that the tip of the wire protrudes 1 or 2 mm.; the proximal end of the wire is connected to the left-arm lead of the electrocardiogram by an alligator clip (Fig. 1). The catheter, with its contained wire, is introduced to a median basilic vein percutaneously or by incision; as the catheter is advanced, the electrocardiogram is used to . . .