Delivery Tube Research Articles

Pulsed air jet impingement heat transfer

Impingement heat transfer from a pulsing jet was studied experimentally. The pulsing jet was generated using a valve similar to a ball valve in design, which was rotated at a known frequency. Temporal average heat transfer characteristics of the jet were quantified using a thermographic infrared imaging technique, while the temporal characteristics of the flow were measured using hot-wire anemometry. Jet Reynolds numbers (based on time-average flow rate) in the range 4000–40,000 were investigated for pulsing jet frequencies ranging from the steady jet condition (zero frequency) to approximately 200 Hz. The experimental results indicate that, for the configuration studied, the heat transfer is degraded at all frequencies, generally in the range 0–20% relative to that of the steady jet at the same time-average flow rate. This is in spite of the significant increase in turbulence intensity for the pulsing jet. The power spectral density function for the pulsing jet reveals a dominant peak at the pulsing frequency, with secondary peaks believed to be due to natural frequency of the fluid delivery tubing downstream of the valve. The degradation in heat transfer for the pulsing jet is believed to be due to relatively small turbulent fluctuations superimposed on the instantaneous periodic flow.

Influence of delivery tube position on tube pressure and particle size distribution: A.S. Pedersen et al (Riso National Laboratory, Roskilde, Denmark)

Influence of delivery tube position on tube pressure and particle size distribution: A.S. Pedersen et al (Riso National Laboratory, Roskilde, Denmark)

Intravenous infusion conditions. Implications for pharmacokinetic monitoring.

Drugs are often given intravenously with an expectation that the predicted serum concentrations will be achieved rapidly. Routine pharmacokinetic monitoring of some drugs may be of limited value, unless the effect of intravenous drug delivery systems on serum concentrations is known. In vitro studies have demonstrated that the actual time for complete drug delivery can be markedly longer than predicted and is dependent inter alia on factors including the delivery device, flow rate, injection site, drug volume and tubing diameter. Studies in paediatric patients have shown that the serum concentrations of drugs, including aminoglycosides and chloramphenicol, are strongly influenced by intravenous drug delivery systems. Similarly, data from adult patients have indicated that a drug delivery system can affect serum concentrations of aminoglycosides. Some data are available about the pharmacokinetics of drugs delivered by newer devices, e.g. controlled release infusion systems, membrane devices and implanted pumps, but additional research is needed to determine their predictability of delivery and pharmacokinetics of commonly used drugs. To achieve optimal therapeutic outcomes in patients, it is crucial to understand the impact of an intravenous drug delivery system on serum concentrations and to develop guidelines for pharmacokinetic monitoring.

Black rubber or clear plastic delivery tubing for nitrous oxide: patient preference

Entonox (a 50:50 mixture of nitrous oxide in oxygen) is given via black rubber corrugated tubing in most obstetric units even though this has been superseded by clear plastic tubing in many operating theatres. This trial has shown that more women in labour preferred using plastic rather than black rubber tubing because it was lighter in weight and devoid of the unpleasant smell associated with the latter. Women also suffered a greater degree of dizziness while using the black rubber tubing. Clear plastic tubing seems a sensible alternative for the delivery of Entonox now that the risks associated with the build up of static charge have little importance. It is cheap, odourless and lightweight, it can be cut to any length, fits standard 22 mm connections, is easy to clean and although durable is potentially disposable.

Pressurization and aspiration phenomena at the tip of the metal delivery tube of an annular slit atomizer

Pressurization and aspiration phenomena at the tip of the metal delivery tube of an annular slit atomizer

Mathematical modelling of atom loss in delivery tubing

A mathematical model is presented to establish a relationship between the quantity of trace analyte vapor lost to the surface of delivery tubing and the tubing diameter, while in transit between stages of an instrument. Cold-vapor atomic absorption spectrometry for mercury, hydride generation techniques, and interfaces like the interface between electrothermal vaporization and inductively coupled plasma mass spectrometry all risk significant analyte loss before measurement. The results of this modelling substantiate the results of limited experimental work published elsewhere suggesting the use of the smallest possible tubing diameter for the delivery of atomic vapor through a tube. This diameter is calculable using Poiseuille's formula. Using this model, kinetic theory, and experimental data, the sticking probability for mercury on latex tubing is calculated to be approximately 1.6 × 10−6.

Instrumentation issues in collecting ear-canal acoustic distortion products.

Ear-canal cochlear otoacoustic emission acoustic distortion products (DPs) appear to provide a window into outer hair cell function and are becoming an important noninvasive cochlear evaluation research tool. If they are to become clinically useful, a better understanding of their production and measurement is needed. The magnitude of the DP depends on the acoustic load of the transducer as well as the cochlear input impedance. The ear-canal impedance and the ER-2 and ER-10B acoustic impedance have been measured and predictions of the reverse transfer function were made. Less well understood are observed standing waves in the ear canal at high frequencies. These may be controlled by insertion of the sound delivery tubes deep into the canal. Measurement of the DPs using an Ariel DSP-16 signal processing board is described in a portable PC-notebook configuration. DPs are approximately related to hearing level (HL) according to the formula DP=8−0.5 HL, where both DP and HL are in dB. Several different useful measurement paradigms that have been investigated will be described.

A remote delivery tube with an integral Joule–Thompson valve for the helium liquefier

Remote delivery tubes (RDTs) in Collins and similar types of helium liquefiers interconnect the liquefier with the storage dewar. In these liquefiers the Joule–Thompson (J–T) valve is separately situated in the liquefier cryostat. Therefore there is a regime of J–T heating during the initial cool down of the liquefier, since there is a time lag in reaching the inversion temperature for the J–T valve. The note describes the design, fabrication, and testing of a RDT with an integral J–T valve. A demountable copper cold seal working at a pressure of 15 bar was successfully tested. The J–T valve seat made of Cu-Cr-Zr alloy provided excellent sealing with the stainless-steel valve tip at liquid-helium temperatures. The testing of this RDT with integral J–T showed substantial reduction in cool down time for the liquefier as well as better control of the dewar pressures.

Bending tool for stainless-steel tubes using cryogenic technique

The design of a special bending tool which is used in the formation of 90° bends for the tube-in-tube helium flow passages of a remote delivery tube is described. The concentric thin walled stainless-steel tube assembly is filled with water and cryofrozen before they are clamped into the bending tool. The tubes are bent by pressing the tube using the bending lever over the guiding wheel. The split bush and split cone clamping arrangement ensures that there is no movement of the tubes during the bending operation. This procedure has yielded kink-free bends with good circularity.

Refilling the lens with an inflatable endocapsular balloon: surgical procedure in animal eyes

In this report we describe the surgical details involved in refilling the lenses of 13 rabbit and 3 primate eyes using an inflatable endocapsular balloon to restore accommodation. The procedure involves endocapsular phacoemulsification through a small "buttonhole" or "dumbbell" anterior capsulotomy or minicircular capsulotomy and the simultaneous preservation of capsular integrity, including the zonules and ciliary muscles. An inflatable balloon made of thin silicone membrane is then inserted into the empty capsular bag. A liquid silicone polymer is injected into the balloon through a delivery tube, and the empty capsular bag is refilled by the inflated balloon. The procedure was found to be reproducible, and an accommodation of 6 D was confirmed in one primate eye. Capsular opacification occurred, but the proliferation and migration of residual lens epithelial cells could be hindered by abundant refilling. This lens-refilling technique may provide restoration of accommodation in future cataract surgery.

Aspects of the life-cycle ofMagnibursatus caudofilamentosa(Reimer, 1971) Gibson & KØie, 1991 (digenea, hemiuroidea,derogenidae)

Abstract Magnibursatus caudofilamentosa (Reimer, 1971) Gibson & Køie, 1991 is a common hemiuroid digene-an in the buccal cavity of the stickleback Gasterosteus aculeatus L. in Denmark. Its cercaria, Cercaria caudofilamentosa Reimer, 1971, develops in daughter-sporocysts in the prosobranch Rissoa mem-branacea. The caudal cyst of the infective cercaria is provided anteriorly with a long, thin filament and opposite a posterior appendage with two shorter, sticky ribbons. When harpacticoid copepods manipulate the cercaria entangled in filamentous algae, the cercarial body is injected into the copepod haemocoel through the everted delivery tube. Three-week-old (18°C), unencysted metacercar-iae are infective to sticklebacks.

Aspects of the morphology and life cycle of Lecithocladium excisum (Digenea, Hemiuridae), a parasite of Scomber spp.

Previously undescribed motile cystophorous cercariae which develop in sporocyst-like germinal sacs in the bullomorph opisthobranch Philine aperta are experimentally shown to develop into Lecithocladium excisum (Digenea, Hemiuridae), a common stomach parasite of mackerel Scomber scombrus in the north-east Atlantic and adjacent seas. Between 3 and 8% of P. aperta from the northern Øresund, Denmark, were infected with cercariae of L. excisum. Ninety per cent were infected with Rhopalura sp. (Orthonectida). Copepods of the genera Acartia, Paracalanus, Pseudocalanus, Eurytemora and Oithona were experimentally infected. Pressure exerted by their mouth limbs caused delivery tube eversion and the injection of the eercarial body into the copepod haemocoel. The metacercariae did not grow in the above mentioned hosts at 12°C, but 590 μm long metacercariae developed within 22 days in laboratory-reared A. tonsa at 18°C. The ctenophore Pleurobrachia pileus and the holoplanktonic polychaete Tomopteris helgolandica, which were found to be naturally infected with metacercariae of L. excisum, may act as transport hosts.

Near-IR retinal laser Doppler velocimetry and flowmetry: new delivery and detection techniques

In laser Doppler velocimetry and flowmetry of the human ocular fundus, near infrared diode lasers, coupled with avalanche photodiode detectors, offer much improved signal-to-noise ratio compared to He-Ne laser delivery and photomultiplier tube detection. The increased signal-to-noise ratio is achieved through increased retinal irradiance and better quantum efficiency of the avalanche photodiode in the near infrared. Furthermore, the small size of the diode lasers allows delivery of two individually steerable beams for simultaneous measurements in different parts of the fundus. Applications are given as illustrations of the capabilities of the system: retinal laser Doppler velocimetry in humans without need for pupil dilatation and optic nerve head laser Doppler flowmetry in the cat using flicker as a stimulus to induce blood flow changes.

Early-Season Control of Chinch Bugs in Corn with Soil Insecticides, 1989

Abstract Pioneer 3320’ field corn was planted for Tests I—III on 6 Apr and for Test IV on 19 Apr in loessial silt loam (Gigger-Gilbert complex) at the Macon Ridge branch of the LSU Northeast Research Station. Granular insecticides were applied at planting using a 2-row John Deere Model 71 Flexi-Planter, modified to carry 1-pt jars of insecticide. Jars were inverted above funnels connected by flexible delivery tubes to either a 7-inch band or an in-furrow application. The diam of a single central fole in the lid of each jar, in combination with tractor speed, determined the rate of insecticide flow. Banded insecticides were applied in front of the press wheel and further incorporated by a drag chain attached to the rear of the planter. Liquid insecticides were applied using a carbon dioxode pressurized planter-mounted sprayer dispensing insecticide from 2-liter plastic bottles. Application pressure was 50 psi using a Tee Jet no. 11004 nozzle. Banded sprays were applied as 8-inch bands across the open seed furrow ahead of the press wheel. For in-furrow spray applications, nozzles were rotated 90° and the spray directed into the open seed furrow A drag chain behind the press wheel provided slight additional incorporation after closure of the seed furrow. Tests were conducted in a randomized complete block design with 4 replications, each treatment consisting of 2, 40-ft rows spaced 36 inches apart. Efficacy of insecticide treatments against chinch bugs in corn were determined by counting the number of chinch bugs/10 randomly selected plants in each insecticide plot (5 plants/row × 2 rows/plot × 4 replications) The number of chinch bug-damaged plants per 40 row ft was also counted in each insecticide plot (2 rows/plots × 4 replications). Data are reported as mean number of chinch bugs/10 plants and mean number of damaged plants/40 row ft.

Chinch Bug Control in Sorghum with Liquid and Granular Soil Insecticides, 1989

Abstract Funks G522 DR' grain sorghum was planted 21 Aug in loessial silt loam (Gigger-Gilbert complex) at the Macon Ridge branch of the LSU Northeast Research Station, adjacent to a recently harvested corn field to take advantage of chinch bugs seeking fresh vegetation on which to feed and produce the final fall generation. Granular insecticides were applied at planting using a 2-row John Deere Model 71 Flexi-Planter, modified to carry 1-pt jars of insecticide. Jars were inverted above funnels connected by flexible delivery tubes to either a 7-inch band or an in-furrow applicator. The diameter of a single central hole in the lid of each jar, in combination with tractor speed, determined the rate of insecticide flow. Banded insecticides were applied in front of the press wheel and further incorporated by a drag chain attached to the rear of the planter. Liquid insecticides were applied using a carbon dioxide pressurized planter-mounted sprayer dispensing insecticide from 2-liter plastic bottles. Application pressure was 50 psi using a Tee Jet #11004 nozzle. Banded sprays were applied as 8-inch bands across the open seed furrow ahead of the press wheel. For in-furrow spray applications, nozzles were rotated 90 degrees and spray directed into the open seed furrow. A drag chain behind the press wheel provided slight additional incorporation after closure of the seed furrow. A randomized complete block design with 4 replications was used, and each treatment consisted of two 40-ft rows spaced 36 inches apart. Efficacy of insecticide treatments against chinch bugs in sorghum were determined by counting the number of chinch bugs/10 randomly selected plants in each insecticide plot (5 plants/row × 2 rows/plot × 4 replications). The number of plants/40 ft of row was also counted in each insecticide plot (2 rows/plot × 4 replications). Data are reported as mean number of chinch bugs/10 plants and mean number of plants/40 ft of row.

On the life history and functional morphology of Halipegus occidualis (Trematoda: Hemiuridae), with emphasis on the cystophorous cercaria stage

The cystophorous cercariae of Halipegus occidualis develop in rediae in the pulmonate snail, Helisoma anceps. Fully developed cercariae are shed from the snail and remain motionless on pond substrata. Manipulation of the caudal appendage by feeding microcrustaceans (copepods and ostracods) results in instantaneous eversion of the delivery tube within the cyst, through which the cercarial body is expelled into the crustacean hemocoel, wherein mesocercariae develop. Morphological and field evidence indicates that mesocercariae become metacercariae in the intestine of several species of larval odonate nymphs when they prey upon microcrustacea. The life cycle is completed when green frogs, Rana clamitans, ingest infected odonates. Phase contrast microscopy, scanning and transmission electron microscopy reveal that the tegument of the cercarial body is covered by microvilli, but internally lacks cellular and tissue differentiation. The apical portion of the delivery tube is covered by glandular papillae and the tip possesses a spined structure. Both represent modifications facilitating penetration and anchorage of the delivery tube through the crustacean intestine. While within the cyst, the body of the cercaria appears to be in a state of anhydrobiosis, an adaptation which presumably prolongs the life of this infective stage and enhances the temporal opportunity for transmission to microcrustacean hosts.

On the morphology and life-history of Hemiurus luehei Odhner, 1905 (Digenea: Hemiuridae)

Previously undescribed cystophorous cercariae which develop in sporocyst germinal sacs in the tectibranch opisthobranch Philine denticulata (Adams) are shown to be cercariae of Hemiurus luehei Odhner, 1905 (Hemiuridae), a common stomach parasite of clupeid and salmonid fishes off the Atlantic coast of Europe, in the Baltic and the Mediterranean Sea. The free-swimming cercariae are seized by calanoid copepods. Temora longicornis (Müller) and Acartia tonsa Dana acted as suitable experimental intermediate hosts. Pressure by the copepod mouth appendages causes delivery tube eversion and the injection of the cercarcial body into the haemocoel. Sagitta sp. was found naturally infected with a metacercaria of H. luehei. The cystophorous cercaria and metacercaria are described using light and scanning electron microscopy. Adults from herring were examined under the stereoscan electron microscope.

Dynamic response characteristics of an impinging‐jet amperometric detector

AbstractA dynamic response experiment at an impinging‐jet detector indicated that laminar flow in the straight delivery tube was modified by mixing stages in the electrode channel and its connections. The response obtained, resulting from this final dispersion, defines an effective detection volume of 7 μL. In a practical flow injection line made from a number of connectors, coils, and so on, this small volume ensured that the detector described here, which incorporated a well‐activated glassy carbon electrode, would not be expected to contribute significantly to the overall dispersion.

Bain circuit delivery tube obstructions

Bain circuit delivery tube obstructions

Evaluation of a new high capacity, all-tantalum molecular-beam-epitaxy arsenic cracker furnace

A novel effusion furnace for the production of As2 from As4 by combined thermal and catalytic cracking has been evaluated in a Varian GEN II molecular-beam epitaxy (MBE) system. The furnace consists of two temperature zones with a one-piece all-tantalum combined crucible, delivery tube, and cracking zone. Ta baffles are inserted into the cracking zone. Thermal isolation of the ‘‘warm’’ sublimation zone and the ‘‘hot’’ cracking zone is achieved by water or liquid nitrogen cooling of the sublimation zone. With the cracking zone at 1500 °C and no power to the 200 cc capacity sublimator, the sublimation zone rises to only 75 °C. Cracking of As4 begins at about 750 °C and saturates at about 900 °C. The As flux stabilizes in about 1.25 h. Installation of the cracker furnace in a position previously used for the old As effusion furnace resulted in considerable outgassing due to the previous condensation of As and trapped impurities on the cryoshroud around the mouth of the old furnace. Soon after installation, growth of nominally undoped GaAs in the As4 mode (by holding the cracking zone at 400 °C) gave background doping concentrations of p=2×1014/cm3, but the first attempts at growth of nominally undoped GaAs with As2 gave high n-type background doping levels due to the outgassing mentioned above. A combination of secondary ion mass spectroscopy (SIMS) and photoluminescence analysis showed decreased C and increased S in the As2 grown layers. Following mechanical scraping and extended thermal cleaning of the shroud area around the cracking zone, the residual As2 background doping dropped dramatically (to high 1013/cm3) while still remaining n type. Material and device benefits we have observed for As2 grown GaAs and (Al,Ga)As are: slightly improved surface morphology, decreased C incorporation, increased doping efficiency in (Al,Ga)As:Si, greatly improved low-temperature photoluminescence, and excellent heterojunction acoustic charge transport (HACT) device results.