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Tubing
Kinds of Tubing Selected AbstractsA New Multilevel Ground Water Monitoring System Using Multichannel TubingGROUND WATER MONITORING & REMEDIATION, Issue 4 2002Murray D. Einarson A new multilevel ground water monitoring system has been developed that uses custom-extruded flexible 1.6-inch (4.1 cm) outside-diameter (O.D.) multichannel HOPE tubing (referred to as Continuous Multichannel Tubing or CMT) to monitor as many as seven discrete zones within a single borehole in either unconsolidated sediments or bedrock. Prior to inserting the tubing in the borehole, ports are created that allow ground water to enter six outer pie-shaped channels (nominal diameter = 0.5 inch [1.3 cm]) and a central hexagonal center channel (nominal diameter = 0.4 inch [1 cm]) at different depths, facilitating the measurement of depth-discrete piezometric heads and the collection of depth-discrete ground water samples. Sand packs and annular seals between the various monitored zones can be installed using conventional tremie methods. Alternatively, bentonite packers and prepacked sand packs have been developed that are attached to the tubing at the ground surface, facilitating precise positioning of annular seals and sand packs. Inflatable rubber packers for permanent or temporary installations in bedrock aquifers are currently undergoing site trials. Hydraulic heads are measured with conventional water-level meters or electronic pressure transducers to generate vertical profiles of hydraulic head. Ground water samples are collected using peristaltic pumps, small-diameter bailers, inertial lift pumps, or small-diameter canister samplers. For monitoring hydrophobic organic compounds, the CMT tubing is susceptible to both positive and negative biases caused by sorption, desorption, and diffusion. These biases can be minimized by: (1) purging the channels prior to sampling, (2) collecting samples from separate 0.25-inch (0.64 cm) O.D. Teflon sampling tubing inserted to the bottom of each sampling channel, or (3) collecting the samples downhole using sampling devices positioned next to the intake ports. More than 1000 CMT multilevel wells have been installed in North America and Europe to depths up to 260 feet (79 m) below ground surface. These wells have been installed in boreholes created in unconsolidated sediments and bedrock using a wide range of drilling equipment, including sonic, air rotary, diamond-bit coring, hollow-stem auger, and direct push. This paper presents a discussion of three field trials of the system, demonstrating its versatility and illustrating the type of depth-discrete data that can be collected with the system. [source] Limiting light-induced lipid peroxidation and vitamin loss in infant parenteral nutrition by adding multivitamin preparations to IntralipidACTA PAEDIATRICA, Issue 3 2001KM Silvers Parenteral lipids are susceptible to light-induced peroxidation, particularly under phototherapy. Ascorbic acid is protective. The aim of this study was to investigate whether dark delivery tubing and/or coadministration of multivitamin preparations could prevent peroxidation of Intralipid without undue vitamin loss. In experiments carried out on the benchtop, lipid peroxidation occurred in ambient light and was more extensive under phototherapy. Dark tubing decreased peroxide formation, but only by about 65%. In simulated clinical conditions in which solutions were pumped through standard clear or dark minibore plastic tubing, Intralipid accumulated lipid peroxides as measured by the FOX assay (280 ,M) or as triglyceride hydroperoxides (52 ,M). Multivitamin preparations (MVIP or Soluvit/Vitlipid) inhibited peroxide formation almost completely, and were fully protective when used with dark tubing. There was loss of riboflavin (65% from Soluvit and 35% from MVIP) in clear tubing but this was decreased to 18% and 11%, respectively, in dark tubing. Ascorbate loss was 20% (MVIP) and 50% (Soluvit) and only slightly less in dark tubing. Ascorbate loss was also seen in the absence of Intralipid and is due to riboflavin-induced photo-oxidation. Conclusion: Multivitamin preparations protect Intralipid against light-induced formation of lipid hydroperoxides, and administering multivitamins with Intralipid via dark delivery tubing provides a practical way of preventing peroxidation of the lipid while limiting vitamin loss. This procedure should be considered for routine use as well as with phototherapy. [source] Does limb angular motion raise limb arterial pressure?ACTA PHYSIOLOGICA, Issue 3 2009D. D. Sheriff Abstract Aim:, Mechanical factors such as the muscle pump have been proposed to augment flow by several mechanisms. The potential for limb angular motion to augment local perfusion pressure (pressure = ½,r2,2, where , is the fluid density, r the radius and , the angular velocity) has been overlooked. We sought to test the hypothesis that limb angular motion augments limb arterial pressure. Methods:, Nine human subjects performed horizontal shoulder flexion (,±90° at 0.75 Hz for 30 s). We measured finger arterial pressure (photoplethysmography) in the moving (Trial 1) and non-moving arm (Trial 2) in separate trials along with the pressure (strain gauge) generated at the fingers within a length of water-filled tubing mounted on the moving arm in both trials. Results:, Arm swinging raised (P < 0.05) the mean pressure measured in the tubing by 11 ± 2 and 14 ± 2 mmHg (Trials 1 and 2 respectively). In response to exercise, the rise in mean finger arterial pressure in the swinging limb (18 ± 3 mmHg, Trial 1) exceeded (P < 0.05) the rise in the resting limb (8 ± 2 mmHg, Trial 2) by an amount similar to the 11 mmHg rise in pressure generated in the tubing in Trial 1. Conclusions:, We conclude that the swinging of a limb creates centrifugal force (a biomechanical centrifuge) which imparts additional pressure to the arteries, but not the veins owing to the venous valves, which further widens the arterial,venous pressure difference. [source] The Liposuction Apparatus "Suspension Device": Hi-Plane LiposculptureDERMATOLOGIC SURGERY, Issue 6 2000Paul Weber MD Background The improvement of liposuction equipment and techniques has resulted in a cumbersome operating room array of aspirator hoses, irrigation/infiltration tubing, and the insulated command and control wiring of current ultrasonic or power liposuction devices. This situation is further complicated by the presence of a second surgeon, the concomitant use of additional traditional or ultrasonic cannulas, and the suction hose of a second aspirator. Objective To solve the problems of sterility and operating room organization, the authors describe a simple, releasable suspension design. Method This apparatus can be temporarily or permanently installed in minutes and is easily maintained to control numerous sterile hoses and wires required for certain liposuction procedures. Results This suspension method appeared to enhance the efficiency and ease of use by single and dual surgeons during cases utilizing ultrasonic and nonultrasonic cannulas. The time savings and ease of use was most noticeable in cases of dual surgeons using both ultrasonic and nonultrasonic systems simultaneously. In addition, surgical personnel were freed for other tasks. Single-surgeon, traditional liposuction was less notably facilitated in terms of speed and fewer personnel. However, wiring and tubing control is facilitated in any case. Conclusion A simple liposuction suspension system facilitates the liposuction procedure to varying degrees depending upon the number of surgeons and devices in simultaneous use. [source] A Single Ventilator for Multiple Simulated Patients to Meet Disaster SurgeACADEMIC EMERGENCY MEDICINE, Issue 11 2006Greg Neyman MD Objectives To determine if a ventilator available in an emergency department could quickly be modified to provide ventilation for four adults simultaneously. Methods Using lung simulators, readily available plastic tubing, and ventilators (840 Series Ventilator; Puritan-Bennett), human lung simulators were added in parallel until the ventilator was ventilating the equivalent of four adults. Data collected included peak pressure, positive end-expiratory pressure, total tidal volume, and total minute ventilation. Any obvious asymmetry in the delivery of gas to the lung simulators was also documented. The ventilator was run for almost 12 consecutive hours (5.5 hours of pressure control and more than six hours of volume control). Results Using readily available plastic tubing set up to minimize dead space volume, the four lung simulators were easily ventilated for 12 hours using one ventilator. In pressure control (set at 25 mm H2O), the mean tidal volume was 1,884 mL (approximately 471 mL/lung simulator) with an average minute ventilation of 30.2 L/min (or 7.5 L/min/lung simulator). In volume control (set at 2 L), the mean peak pressure was 28 cm H2O and the minute ventilation was 32.5 L/min total (8.1 L/min/lung simulator). Conclusions A single ventilator may be quickly modified to ventilate four simulated adults for a limited time. The volumes delivered in this simulation should be able to sustain four 70-kg individuals. While further study is necessary, this pilot study suggests significant potential for the expanded use of a single ventilator during cases of disaster surge involving multiple casualties with respiratory failure. [source] An accessible micro-capillary electrophoresis device using surface-tension-driven flowELECTROPHORESIS, Issue 9 2009Swomitra K. Mohanty Abstract We present a rapidly fabricated micro-capillary electrophoresis chip that utilizes surface-tension-driven flow for sample injection and extraction of DNA. Surface-tension-driven flow (i.e. passive pumping) [G. M. Walker et al., Lab. Chip. 2002, 2, 131,134] injects a fixed volume of sample that can be predicted mathematically. Passive pumping eliminates the need for tubing, valves, syringe pumps, and other equipment typically needed for interfacing with microelectrophoresis chips. This method requires a standard micropipette to load samples before separation, and remove the resulting bands after analysis. The device was made using liquid phase photopolymerization to rapidly fabricate the chip without the need of special equipment typically associated with the construction of microelectrophoresis chips (e.g. cleanroom) [A. K. Agarwal et al., J. Micromech. Microeng. 2006, 16, 332,340; S. K. Mohanty et al., Electrophoresis 2006, 27, 3772,3778]. Batch fabrication time for the device presented here was 1.5,h including channel coating time to suppress electroosmotic flow. Devices were constructed out of poly-isobornyl acrylate and glass. A standard microscope with a UV source was used for sample detection. Separations were demonstrated using Promega BenchTop 100,bp ladder in hydroxyl ethyl cellulose (HEC) and oligonucleotides of 91 and 118,bp were used to characterize sample injection and extraction of DNA bands. The end result was an inexpensive micro-capillary electrophoresis device that uses tools (e.g. micropipette, electrophoretic power supplies, and microscopes) already present in most labs for sample manipulation and detection, making it more accessible for potential end users. [source] Integration of continuous-flow sampling with microchip electrophoresis using poly(dimethylsiloxane)-based valves in a reversibly sealed deviceELECTROPHORESIS, Issue 14 2007Michelle W. Li Abstract Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39,nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n,=,10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90,s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions. [source] Nanowires for surface enlargement of narrow-bore fused-silica tubingELECTROPHORESIS, Issue 21-22 2004Andreas Woldegiorgis Abstract A method for preparation of silica nanowires with dimensions of d = 10,100 nm, l = 5,500 nm, is described. The nanostructured material is an integral part of the inner surface of narrow bore fused-silica capillary tubing. The wire preparation method is based on a decomposition of 2-chloro-1,1,2-trifluoroethyl methyl ether at elevated temperature and pressure. The silica bulk material is rearranged via a sustained silica-hydrogen fluoride chemistry, and reaction mechanisms for this process are proposed. The method is suitable for preparing long lengths of tubing with the modified surface. It is our belief that the texture of the capillary wall with its increased surface area is useful for applications such as microreactions, catalysis, and high-resolution pressure and/or electrodriven open-tubular liquid chromatography. [source] Field testing of equilibrium passive samplers to determine freely dissolved native polycyclic aromatic hydrocarbon concentrationsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2008Gerard Cornelissen Abstract Equilibrium passive samplers are promising tools to determine freely dissolved aqueous concentrations (CW,free) of hydrophobic organic compounds. Their use in the field, however, remains a challenge. In the present study on native polycyclic aromatic hydrocarbons (PAHs) in Oslo Harbor, Norway, two different passive sampler materials, polyoxymethylene (POM; thickness, 55 ,m [POM-55] and 500 ,m [POM-500]) and polydimethylsiloxane (PDMS; thickness, 200 ,m), were used to determine in the laboratory CW,free in sediment pore water (CPW,free), and the suitability of five passive samplers for determination of CW,free in overlying surface water was tested under field conditions. For laboratory determinations of CPW,free, both POM-55 and PDMS turned out to be suitable. In the field, the shortest equilibrium times (approximately one month) were observed for POM-55 and PDMS (thickness, 28 ,m) coatings on solid-phase microextraction fibers, with PDMS tubing as a good alternative. Low-density polyethylene (thickness, 100 ,m) and POM-500 did not reach equilibrium within 119 d in the field. Realistic values were obtained for dissolved organic carbon,water partition coefficients in the field (approximately one log unit under log KOW), which strengthened the conclusion that equilibrium was established in field-exposed passive samplers. At all four stations, chemical activity ratios between pore water and overlying water were greater than one for all PAHs, indicating that the sediment was a PAH diffusion source and that sediment remediation may be an appropriate treatment for PAH contamination in Oslo Harbor. [source] Effect of volatile hydrocarbon fractions on mobility and earthworm uptake of polycyclic aromatic hydrocarbons from soils and soil/lampblack mixturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2005Bill W. Bogan Abstract Studies were conducted to examine the mobility and bioavailability to earthworms (Eisenia fetida) of priority pollutant polycyclic aromatic hydrocarbons (PAH) in a suite of 11 soils and soil/lampblack mixtures obtained from former manufactured-gas plant sites. Contaminant mobility was assessed using XAD4 resins encapsulated in dialysis tubing, which were exposed to slurried soils for 15 d. These experiments showed that mobility of PAH in the different soils strongly correlated to the levels of volatile hydrocarbons (namely, gasoline- and diesel-range organics [GRO and DRO]) that existed in the soils as co-contaminants. Actual PAH bioavailability (as measured by earthworm PAH concentrations) also appeared to depend on GRO + DRO levels, although this was most evident at high levels of these contaminants. These findings are discussed in view of the effects of diesel-range organics on oil viscosity, assuming that the hydrocarbon contaminants in these soils exist in the form of distinct adsorbed oil phases. This study, therefore, extends correlations between carrier-oil viscosity and dissolved solute bioavailability, previously observed in a number of other in vitro and whole-organism tests (and in bacterial mutagenicity studies in soil), to multicellular organisms inhabiting contaminated-soil systems. [source] Controlled release experiments with nonylphenol in aquatic microcosmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Gerd Pfister Abstract A method of controlled release of technical nonylphenol (tNP) was developed to simulate realistic exposure in ecotoxicological studies on aquatic organisms. The direct addition of tNP from an aqueous stock solution into 50 ml of water led to a concentration decrease of 80 to 90% weight/volume (w/v) from nominal values within 48 h. The inclusion of tNP in semipermeable low-density polyethylene (LDPE) lay-flat tubing (controlled-release devices [CRDs]) of different length allowed a continuous release into pure water at a rate of about 30 ,g/cm2/d. Using CRDs in aquaria containing 15 L of 63-,m-filtered lake water, eight different concentrations with maxima between 38.1 and 326.7 ,g/L were maintained for 11 d. During a second experiment in 15-L aquaria, five replicates of three concentrations were maintained using CRDs of the same length. Concentrations after 38 d varied between 0.1 and 6.7, 26.1 and 41.9, and 49.9 and 76.0 ,g/L. In aquatic microcosms containing 230 L of lake water, a natural plankton community, 50 L of sediment, and macrophytes, seven different tNP concentrations (maxima 11,120.1 ,g/L) were maintained over 45 d using CRDs of different length. They were replaced after 14 and 25 d because release of tNP was slower than predicted from laboratory experiments. Concentrations in the top 1-cm sediment layer were on average 19 times higher during the dosing period than concentrations in the water at the same time. In the sediments, different levels of applications led to concentrations that differed less distinctly than in the water. This method is suitable for exposing aquatic organisms continuously to constant, ecologically relevant concentrations of NP and represents an improvement over previous dosing methods in which exposure varied. [source] Two-thumb vs Two-finger Chest Compression in an Infant Model of Prolonged Cardiopulmonary ResuscitationACADEMIC EMERGENCY MEDICINE, Issue 10 2000Michele L. Dorfsman MD Abstract. Objective: Previous experiments in the authors swine lab have shown that cardiopulmonary resuscitation (CPR) using two-thumb chest compression with a thoracic squeeze (TT) produces higher blood and perfusion pressures when compared with the American Heart Association (AHA)-recommended two-finger (TF) technique. Previous studies were of short duration (1-2 minutes). The hypothesis was that TT would be superior to TF during prolonged CPR in an infant model. Methods: This was a prospective, randomized crossover experiment in a laboratory setting. Twenty-one AHA-certified rescuers performed basic CPR for two 10-minute periods, one with TT and the other with TF. Trials were separated by 2-14 days, and the order was randomly assigned. The experimental circuit consisted of a modified manikin with a fixed-volume arterial system attached to a neonatal monitor via an arterial pressure transducer. The arterial circuit was composed of a 50-mL bag of normal saline solution (air removed) attached to the manikin chest plate and connected to the transducer with a 20-gauge intravenous catheter and tubing. Rescuers were blinded to the arterial pressure tracing. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were recorded in mm Hg, and pulse pressures (PPs) were calculated. Data were analyzed with two-way repeated-measures analysis of variance. Sphericity assumed modeling, with Greenhouse-Geisser and Huynh-Feldt adjustments, was applied. Results: Marginal means for TT SBP (68.9), DBP (17.6), MAP (35.3), and PP (51.4) were higher than for TF SBP (44.8), DBP (12.5), MAP (23.3), and PP (32.2). All four pressures were significantly different between the two techniques (p , 0.001). Conclusion: In this infant CPR model, TT chest compression produced higher MAP, SBP, DBP, and PP when compared with TF chest compression during a clinically relevant duration of prolonged CPR. [source] A fatigue and creep study in austenitic stainless steel 316L used in exhaust pipes of naval gas turbinesFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2004R. F. MARTINS ABSTRACT Exhaust pipes of naval gas turbines are made of thin wall tubing of stainless steel grade AISI 316L. The tubes are fabricated by butt welding of different sections with longitudinal and circumferential joints. The plate thickness is about 4.0 mm, and the working temperature varies between 600 °C and 400 °C in the critical zones of the pipe, in the lower and central areas, respectively. The loadings in the tube induce high-temperature fatigue and creep-fatigue cracks have nucleated and propagated in the tube near some welded joints. The paper presents FCGR data obtained in CT specimens of used material taken from the pipes and tested at RT, 335, 500 and 600 °C. Preliminary creep data obtained in tension, in thin-sheet specimens (about 4 mm thickness), also taken from the conduct wall and tested at 500, 550 and 600 °C are also given. These results are crucial to perform a fatigue-creep interaction life assessment of the critical parts of the structure in the near future. Finally, the paper presents results of research work to investigate carbide precipitation and formation in virgin thin-sheet specimens subjected to several types of thermal exposures. In some cases, 3,4 d was the time interval between exposures. Grain size measurements were carried out together with microstructural observations in the SEM. The influence of time, temperature and time interval between thermal exposures was assessed comparing the microstructures. [source] Response of soil surface CO2 flux in a boreal forest to ecosystem warmingGLOBAL CHANGE BIOLOGY, Issue 4 2008DUSTIN R. BRONSON Abstract Soil surface carbon dioxide (CO2) flux (RS) was measured for 2 years at the Boreal Soil and Air Warming Experiment site near Thompson, MB, Canada. The experimental design was a complete random block design that consisted of four replicate blocks, with each block containing a 15 m × 15 m control and heated plot. Black spruce [Picea mariana (Mill.) BSP] was the overstory species and Epilobium angustifolium was the dominant understory. Soil temperature was maintained (,5 °C) above the control soil temperature using electric cables inside water filled polyethylene tubing for each heated plot. Air inside a 7.3-m-diameter chamber, centered in the soil warming plot, contained approximately nine black spruce trees was heated ,5 °C above control ambient air temperature allowing for the testing of soil-only warming and soil+air warming. Soil surface CO2 flux (RS) was positively correlated (P < 0.0001) to soil temperature at 10 cm depth. Soil surface CO2 flux (RS) was 24% greater in the soil-only warming than the control in 2004, but was only 11% greater in 2005, while RS in the soil+air warming treatments was 31% less than the control in 2004 and 23% less in 2005. Live fine root mass (< 2 mm diameter) was less in the heated than control treatments in 2004 and statistically less (P < 0.01) in 2005. Similar root mass between the two heated treatments suggests that different heating methods (soil-only vs. soil+air warming) can affect the rate of decomposition. [source] Macro- and Micro-Purge Soil-Gas Sampling Methods for the Collection of Contaminant VaporsGROUND WATER MONITORING & REMEDIATION, Issue 1 2009Brian A. Schumacher Purging influence on soil-gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., system volume) for temporary probes in fine-grained soils, was evaluated at three different field sites. A macro-purge sampling system consisted of a standard, hollow, 3.2-cm outer diameter (OD) drive probe with a retractable sampling point attached to an appropriate length of 0.48-cm inner diameter (ID) Teflon® tubing. The macro-purge sampling system had a purge system volume of 24.5 mL at a 1-m depth. In contrast, the micro-purge sampling systems were slightly different between the field sites and consisted of a 1.27-cm OD drive rod with a 0.10-cm ID stainless steel tube or a 3.2-cm OD drive rod with a 0.0254-cm inner diameter stainless steel tubing resulting in purge system volumes of 1.2 and 7.05 mL at 1-m depths, respectively. At each site and location within the site, with a few exceptions, the same contaminants were identified in the same relative order of abundances indicating the sampling of the same general soil atmosphere. However, marked differences in VOC concentrations were identified between the sampling systems, with micro-purge samples having up to 27 times greater concentrations than their corresponding macro-purge samples. The higher concentrations are the result of a minimal disturbance of the ambient soil atmosphere during purging. The minimal soil-gas atmospheric disturbance of the micro-purge sampling system allowed for the collection of a sample that is more representative of the soil atmosphere surrounding the sampling point. That is, a sample that does not contain an atmosphere that has migrated from distance through the geologic material or from the surface in response to the vacuum induced during purging soil-gas concentrations. It is thus recommended that when soil-gas sampling is conducted using temporary probes in fine-grained soils, the sampling system use the smallest practical ID soil-gas tubing and minimize purge volume to obtain the soil-gas sample with minimal risk of leakage so that proper decisions, based on more representative soil-gas concentrations, about the site can be made. [source] A Case Study of Soil-Gas Sampling in Silt and Clay-Rich (Low-Permeability) SoilsGROUND WATER MONITORING & REMEDIATION, Issue 1 2009Todd A. McAlary Soil-gas sampling and analysis is a common tool used in vapor intrusion assessments; however, sample collection becomes more difficult in fine-grained, low-permeability soils because of limitations on the flow rate that can be sustained during purging and sampling. This affects the time required to extract sufficient volume to satisfy purging and sampling requirements. The soil-gas probe tubing or pipe and sandpack around the probe screen should generally be purged prior to sampling. After purging, additional soil gas must be extracted for chemical analysis, which may include field screening, laboratory analysis, occasional duplicate samples, or analysis for more than one analytical method (e.g., volatile organic compounds and semivolatile organic compounds). At present, most regulatory guidance documents do not distinguish between soil-gas sampling methods that are appropriate for high- or low-permeability soils. This paper discusses permeability influences on soil-gas sample collection and reports data from a case study involving soil-gas sampling from silt and clay-rich soils with moderate to extremely low gas permeability to identify a sampling approach that yields reproducible samples with data quality appropriate for vapor intrusion investigations for a wide range of gas-permeability conditions. [source] A New Multilevel Ground Water Monitoring System Using Multichannel TubingGROUND WATER MONITORING & REMEDIATION, Issue 4 2002Murray D. Einarson A new multilevel ground water monitoring system has been developed that uses custom-extruded flexible 1.6-inch (4.1 cm) outside-diameter (O.D.) multichannel HOPE tubing (referred to as Continuous Multichannel Tubing or CMT) to monitor as many as seven discrete zones within a single borehole in either unconsolidated sediments or bedrock. Prior to inserting the tubing in the borehole, ports are created that allow ground water to enter six outer pie-shaped channels (nominal diameter = 0.5 inch [1.3 cm]) and a central hexagonal center channel (nominal diameter = 0.4 inch [1 cm]) at different depths, facilitating the measurement of depth-discrete piezometric heads and the collection of depth-discrete ground water samples. Sand packs and annular seals between the various monitored zones can be installed using conventional tremie methods. Alternatively, bentonite packers and prepacked sand packs have been developed that are attached to the tubing at the ground surface, facilitating precise positioning of annular seals and sand packs. Inflatable rubber packers for permanent or temporary installations in bedrock aquifers are currently undergoing site trials. Hydraulic heads are measured with conventional water-level meters or electronic pressure transducers to generate vertical profiles of hydraulic head. Ground water samples are collected using peristaltic pumps, small-diameter bailers, inertial lift pumps, or small-diameter canister samplers. For monitoring hydrophobic organic compounds, the CMT tubing is susceptible to both positive and negative biases caused by sorption, desorption, and diffusion. These biases can be minimized by: (1) purging the channels prior to sampling, (2) collecting samples from separate 0.25-inch (0.64 cm) O.D. Teflon sampling tubing inserted to the bottom of each sampling channel, or (3) collecting the samples downhole using sampling devices positioned next to the intake ports. More than 1000 CMT multilevel wells have been installed in North America and Europe to depths up to 260 feet (79 m) below ground surface. These wells have been installed in boreholes created in unconsolidated sediments and bedrock using a wide range of drilling equipment, including sonic, air rotary, diamond-bit coring, hollow-stem auger, and direct push. This paper presents a discussion of three field trials of the system, demonstrating its versatility and illustrating the type of depth-discrete data that can be collected with the system. [source] Use of neural networks for the prediction of frictional drag and transmission of axial load in horizontal wellboresINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2003Tanvir Sadiq Abstract The use of mud motors and other tools to accomplish forward motion of the bit in extended reach and horizontal wells allows avoiding large amounts of torque caused by rotation of the whole drill string. The forward motion of the drill string, however, is resisted by excessive amount of friction. In the presence of large compressive axial loads, the drill pipe or coiled tubing tends to buckle into a helix in horizontal boreholes. This causes additional frictional drag resisting the transmission of axial load (resulting from surface slack-off force) to the bit. As the magnitude of the frictional drag increases, a buckled pipe may become ,locked-up' making it almost impossible to drill further. In case of packers, the frictional drag may inhibit the transmission of set-up load to the packer. A prior knowledge of the magnitude of frictional drag for a given axial load and radial clearance can help avoid lock-up conditions and costly failure of the tubular. In this study a neural network model, for the prediction of frictional drag and axial load transmission in horizontal wellbores, is presented. Several neural network architectures were designed and tested to obtain the most accurate prediction. After cross-validation of the Back Propagation Neural Network (BPNN) algorithm, a two-hidden layer model was chosen for simultaneous prediction of frictional drag and axial load transmission. A comparison of results obtained from BPNN and General Regression Neural Network (GRNN) algorithms is also presented. Copyright © 2002 John Wiley & Sons, Ltd. [source] Two-phase flow convective condensation of refrigerant mixtures under gas/liquid injectionINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2005Samuel M. Sami Abstract The influence of gas/liquid injection on two-phase flow condensation heat transfer characteristics of some refrigerant mixtures in horizontal enhanced surface tubing is presented. Correlations were proposed to predict the impact of the gas/liquid injection on the heat transfer characteristics such as average heat transfer coefficient of R-507, R-404A, R-410A, and R-407C in two-phase flow condensation inside enhanced surface tubing. The data also revealed that gas, liquid and gas/liquid injection is beneficial at certain gas/liquid injection ratios to the heat transfer coefficient depending upon the Reynolds number and the condensation point of the refrigerant mixtures in question. It was also evident that the proposed condensation correlations and the experimental data were applicable to the entire heat and mass flux, investigated in the present study under gas/liquid injection conditions. The deviation between the experimental and predicted under gas/liquid injection were less than ± 10, for the majority of data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Influence of magnetic field on two-phase flow convective boiling of some refrigerant mixturesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2005Samuel M. Sami Abstract In this paper, an experimental study on the influence of magnetohydrodynamic (MHD) on heat transfer characteristics of two-phase flow boiling of some refrigerant mixtures in air/refrigerant horizontal enhanced surface tubing is presented. Correlations were proposed to predict the impact of MHD on the heat transfer characteristics such as average heat transfer coefficients, and pressure drops of R-507, R-404A, R-410A, and R-407C in two-phase flow boiling inside enhanced surface tubing. In addition, it was found that the refrigerant mixture's pressure drop is a weak function of the mixture's composition. It was also evident that the proposed correlations for predicting the heat transfer characteristics were applicable to the entire heat and mass flux, investigated in the present study. The deviation between the experimental and predicted value using new and improved correlations for the heat transfer coefficient and pressure drop were less than ±20%, for the majority of data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of magnetic field on the performance of new refrigerant mixturesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2003Samuel M. Sami Abstract Performance test results of new alternative refrigerant mixtures such as R-410A, R-507, R-407C, and R-404A under various conditions of magnetic field are discussed, analysed and presented. The test results were obtained using an air-source heat pump set-up with enhanced surface tubing under various magnetic field conditions. Performance tests were conducted according to the ARI/ASHRAE Standards. The test results demonstrated that as magnetic field force increases, compressor head pressure and discharge temperature slightly increase as well as less liquid refrigerant is boiling in the compressor shell. This has a positive effect in protecting the compressor. The effect of magnetic field on mixture behaviour varies from one mixture to another depending upon the mixture's composition and its boiling point. Furthermore, the use of magnetic field appears to have a positive influence on the system COP as well as thermal capacities of condenser and evaporator. Copyright © 2002 John Wiley & Sons, Ltd. [source] Study of liquid injection impact on the performance of new refrigerant mixturesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2003Samuel M. Sami Abstract In this paper, the test results of liquid injection impact on the performance of new alternative refrigerant mixtures such as: R-410A, R-507, R-407C and R-404A are discussed, analysed and presented. The test results were obtained using an air-source heat pump set-up with enhanced surface tubing under various liquid injection ratios. Performance tests were conducted according to the ARI/ASHRAE standards. The performance data demonstrated that as liquid injection ratio increases, compressor head pressure and discharge temperature decrease. This has a positive effect in protecting the compressor. The effect of liquid injection on mixture behaviour varies from one mixture to another depending upon the mixture's composition. Furthermore, liquid injection appears to have a significant influence on R-410A behaviour compared to the other mixtures in question. Copyright © 2002 John Wiley & Sons, Ltd. [source] Prevention of urethral stricture in insertion of an inflatable penile prosthesisINTERNATIONAL JOURNAL OF UROLOGY, Issue 2 2008Sung Won Lee Objective: The aim of this study was to find the mechanism that causes urethral stricture with a view to preventing its occurrence after implantation of a three-piece inflatable penile prosthesis. Methods: When implanting a three-piece inflatable penile prosthesis, we draw two longitudinal lines parallel to the long axis of the proximal cylinder and the tubing leading from each cylinder into the cavernosal space, to prevent 360 degree rotation of the cylinder. Results: From September 1993 to February 2007, a total 86 three-piece penile prosthesis implantations were carried out in 70 patients. Urethral stricture occurred in 5.8% (5/86) of the prosthesis operations. Fifteen three-piece penile prosthesis reinsertions were carried out in 17.4% (15/86) of the prosthesis recipients. Conclusions: A successful outcome was achieved in the patients who received penile implantation with the three-piece penile prosthesis that were marked with longitudinal lines. The rotation of the cylinder may cause compression on the urethra from the tubing leading from the cylinder or pump crossing over the urethra and resulting in urethral stricture. The drawing of longitudinal lines at the proximal cylinder and tubing leading from the cylinder could prevent the urethral stricture induced by tubes that are twisted by rotation of the cylinder. [source] Fullerene-Promoted Singlet-Oxygen Photochemical Oxygenations in Glass-Polymer Microstructured ReactorsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2008Tommaso Carofiglio Abstract In this paper we report the fabrication of thiolene-based microstructured reactors (MRs) that have been specifically designed to include solid-supported reagents within the microchannels network. We propose a convenient solution to realize reversible press-fit, leak-proof interconnects that greatly simplify the MR coupling to the external environment such as capillary tubing, sample reservoirs and pumps. The MRs have been used to carry out the oxidation of ,-terpinene and methionine using [60]fullerene, covalently linked to Tentagel® and silica gel matrices, as a singlet oxygen sensitizer. High conversions have been observed for both substrates although, in the case of ,-terpinene, a partial photodegradation of the endo -peroxide product was detected. Interestingly, in the case of methionine, a quantitative conversion to the corresponding sulfoxides was achieved in about 40 seconds, using low-power, white LED illumination. The reaction time is considerably shorter when compared to the batch procedure that requires, for the same process, about one hour illumination and the use of a 300-W tungsten halogen lamp. [source] The chick chorioallantoic membrane as a novel in vivo model for the testing of biomaterialsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002T.I. Valdes Abstract Current in vivo models for testing biomaterials are time and labor intensive as well as expensive. This article describes a new approach for testing biomaterials in vivo using the chorioallantoic membrane (CAM) of the developing chicken embryo, as an alternative to the traditional mammalian models. Fertilized chicken eggs were incubated for 4 days, at which time a small window was cut in the shell of the egg. After 1 week of incubation, the CAM received several test materials, including the endotoxin LPS, a cotton thread and a Silastic tubing. One day and 1 week later, the tissue response to the test materials was assessed using gross, histological, and scanning electron microscope evaluations. The inflammatory response of the chorioallantoic membrane to biomaterials was fully characterized and found to be similar to that of the mammalian response and was also seen to vary according to test materials. We also found that the structure and geometry of the test materials greatly influenced the incorporation of the samples in the CAM. The similarity of the tissue response of the CAM with the mammalian models, plus the low cost, simplicity, and possibility to continuously visualize the test site through the shell window make this animal model particularly attractive for the rapid in vivo screening of biomaterials. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 273,282, 2002 [source] Separation of chiral mixtures in real SMB units: The FlexSMB-LSRE®AICHE JOURNAL, Issue 1 2010Pedro Sá Gomes Abstract In this work, a procedure for the separation of a racemic mixture of guaifenesin onto a chiral stationary phase (Chiralpak AD), by means of Simulated Moving Bed (SMB) technology, is presented in four major steps: (1) search for the suitable stationary and mobile phases; (2) determination of sorption parameters and validation by frontal analysis; (3) modeling and design of the SMB unit; and (4) operation and demonstration. A major emphasis is given to the common deviations that "real" SMB units present when compared with the theoretical apparatus (due to tubing and equipment dead volumes, switching time asymmetries and delays, pumps flow rates variations). These deviations are analyzed before and after the design and construction of the FlexSMB-LSRE® unit, a new flexible unit, hereby presented. A detailed model that takes into account tubing and equipment dead volumes, as well as switching time asymmetries and delay, was used to study and compare different dead volumes design and compensating strategies. It is shown that all these approaches can be converged into a switching time compensating strategy. This approach served to predict the experimental operating conditions and run a classical SMB experiment, which afterwards was compared with the simulated profiles obtained for the FlexSMB-LSRE® unit. The result of the separation was guaifenesin enantiomers with purities above 98% and a productivity value of 23 genantiomer/(dm3 CSP day). © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Functional characterization of prostaglandin F2, receptor in the spinal cord for tactile pain (allodynia)JOURNAL OF NEUROCHEMISTRY, Issue 2 2003Tadatoshi Muratani Abstract Prostaglandin F2, (PGF2,) binds to its receptor (FP) to increase the intracellular-free calcium concentration ([Ca2+]i) by coupling of FP with Gq protein. Spinal intrathecal administration of PGF2, to mouse induces touch-evoked pain (mechanical allodynia), in which capsaicin-insensitive primary afferent A,-fibres and N -methyl- d -aspartate receptor ,4 subunit are involved. FP in the spinal cord, however, was not well characterized. Here, we showed constitutive expression of FP mRNA in mouse spinal cord, and functionally characterized spinal FP-expressing cells which were involved in PGF2, -induced mechanical allodynia. The method for repetitive administration of oligodeoxyribonucleotides through tubing to conscious mice was established for mechanical allodynia evaluation. We identified an antisense oligodeoxyribonucleotide targeting FP mRNA, causing both disappearance of PGF2, -induced mechanical allodynia and decrease of FP mRNA. With saline-administered mice, PGF2, rapidly increased [Ca2+]i of the cells in the deeper layer of the dorsal horn. In contrast, when the FP antisense oligodeoxyribonucleotide was repeatedly administered, the population of PGF2, -responsive cells in the slices reduced, and PGF2, -induced [Ca2+]i increase of these cells diminished. These data strongly suggested that, in the dorsal horn of the spinal cord, there are the FP-expressing cells which are involved in PGF2, -induced mechanical allodynia. [source] Safe Criteria and Procedure for Kangaroo Care With Intubated Preterm InfantsJOURNAL OF OBSTETRIC, GYNECOLOGIC & NEONATAL NURSING, Issue 5 2003FAAN professor, Susan M. Ludington-Hoe CNM Kangaroo care (KC) was safely conducted with mechanically ventilated infants who weighed less than 600 grams and were less than 26 weeks gestation at birth. These infants, ventilated for at least 24 hours at the time of the first KC session, were considered stable on the ventilator at low settings (intermittent mandatory ventilation < 35 breaths per minute and FiO2 < 50%), had stable vital signs, and were not on vasopressors. A protocol for implementation of KC with ventilated infants that uses a standing transfer, with two staff members assisting to minimize the possibility of extubation, is presented. Also discussed is the positioning of the ventilator tubing during KC. This protocol was implemented without any accidental extubation throughout an experimental research study. The criteria and protocol were compared to those available in published reports and revealed many similar elements, providing additional support for the recommended protocol. No adverse events occurred with the criteria and protocol reported here, suggesting that they can be adopted for broader use. [source] Release-modulating factors strongly affecting steroid diffusion from silicone elastomer,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2004Harold A. Nash Abstract Investigations were undertaken to determine the cause of decreases over time in the release rate from levonorgestrel (LNG) implants consisting of silicone elastomer tubing filled with crystalline steroid. Emptying and refilling with the same steroid partially restored release rate. Surprisingly, a further increment in release rates was attained if the tubing was briefly irrigated with methanol before refill. Fractional crystallization showed that release-modulating factors could be concentrated in mother liquors and were initially present as impurities. Boiling LNG in ethanol or methanol produced a number of release-modulating factors of which the most prominent was also found in one production lot of LNG. It was identified as 6,-hydroxy-levonorgestrel (6,-OH-LNG). Added to LNG at the 2% level, 6,-OH-LNG decreased the release rate by 27%. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:2420,2430, 2004 [source] PULSES OF PHOSPHATE PROMOTE DOMINANCE OF THE TOXIC CYANOPHYTE CYLINDROSPERMOPSIS RACIBORSKII IN A SUBTROPICAL WATER RESERVOIR,JOURNAL OF PHYCOLOGY, Issue 3 2009Amanda J. Posselt The role of dissolved inorganic phosphorus (DIP) in promoting dominance of the toxic nitrogen (N)-fixing cyanobacterium Cylindrospermopsis raciborskii (Wo,osz.) Seenayya et Subba Raju was examined in a subtropical water reservoir, Lake Samsonvale (=North Pine reservoir). A novel in situ bioassay approach, using dialysis tubing rather than bottles or bags, was used to determine the change in C. raciborskii dominance with daily additions of DIP. A statistically significant increase in dominance of C. raciborskii was observed when DIP was added at two concentrations (0.32 ,M and 16 ,M) in a daily pulse over a 4 d period in three separate experiments in the summer of 2006/2007. There was an increase in both C. raciborskii cell concentrations and biovolume in two DIP treatments, but not in the ammoniacal N + DIP treatment. In addition, overall phytoplankton cell concentrations increased with DIP addition, indicating that Lake Samsonvale was DIP limited at the time of experiments. Given the bioassay response, it is likely that dominance of C. raciborskii could increase in Lake Samsonvale with periodic injections of DIP such as inflow events. [source] | ||||||||||||||||||||||||||||||||||