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Sample records for gas distension technique

  1. Distensibility and pain of the uterine cervix evaluated by novel techniques.

    PubMed

    Gregersen, Hans; Hee, Lene; Liao, Donghua; Uldbjerg, Niels

    2016-07-01

    The article serves to review the literature on the human uterine cervix based on a new distension technology named functional luminal imaging probe. This technology was originally developed to study the biomechanical competence of the gastro-esophageal junction where it provides a geometric profile of the lumen during distension, which can be related to sensory data. We searched and reviewed publications on cervical distention from 2002. The functional luminal imaging probe technology has been used for studying the mechanical and mechano-sensory properties of the cervix in non-pregnant women. In early pregnant women and in term pregnant women, the technique provides geometric measurements from the whole cervical canal during distension, which changes dramatically during pregnancy. Furthermore, it has been demonstrated that the technique predicts the outcome of labor induction better than the Bishop score does. The functional luminal imaging probe technology has potential as a research tool as well as for clinical use in gynecology and obstetrics. PMID:26946059

  2. Photonic sensing of arterial distension

    PubMed Central

    Ruh, Dominic; Subramanian, Sivaraman; Sherman, Stanislav; Ruhhammer, Johannes; Theodor, Michael; Dirk, Lebrecht; Foerster, Katharina; Heilmann, Claudia; Beyersdorf, Friedhelm; Zappe, Hans; Seifert, Andreas

    2016-01-01

    Most cardiovascular diseases, such as arteriosclerosis and hypertension, are directly linked to pathological changes in hemodynamics, i.e. the complex coupling of blood pressure, blood flow and arterial distension. To improve the current understanding of cardiovascular diseases and pave the way for novel cardiovascular diagnostics, innovative tools are required that measure pressure, flow, and distension waveforms with yet unattained spatiotemporal resolution. In this context, miniaturized implantable solutions for continuously measuring these parameters over the long-term are of particular interest. We present here an implantable photonic sensor system capable of sensing arterial wall movements of a few hundred microns in vivo with sub-micron resolution, a precision in the micrometer range and a temporal resolution of 10 kHz. The photonic measurement principle is based on transmission photoplethysmography with stretchable optoelectronic sensors applied directly to large systemic arteries. The presented photonic sensor system expands the toolbox of cardiovascular measurement techniques and makes these key vital parameters continuously accessible over the long-term. In the near term, this new approach offers a tool for clinical research, and as a perspective, a continuous long-term monitoring system that enables novel diagnostic methods in arteriosclerosis and hypertension research that follow the trend in quantifying cardiovascular diseases by measuring arterial stiffness and more generally analyzing pulse contours. PMID:27699095

  3. Photonic sensing of arterial distension

    PubMed Central

    Ruh, Dominic; Subramanian, Sivaraman; Sherman, Stanislav; Ruhhammer, Johannes; Theodor, Michael; Dirk, Lebrecht; Foerster, Katharina; Heilmann, Claudia; Beyersdorf, Friedhelm; Zappe, Hans; Seifert, Andreas

    2016-01-01

    Most cardiovascular diseases, such as arteriosclerosis and hypertension, are directly linked to pathological changes in hemodynamics, i.e. the complex coupling of blood pressure, blood flow and arterial distension. To improve the current understanding of cardiovascular diseases and pave the way for novel cardiovascular diagnostics, innovative tools are required that measure pressure, flow, and distension waveforms with yet unattained spatiotemporal resolution. In this context, miniaturized implantable solutions for continuously measuring these parameters over the long-term are of particular interest. We present here an implantable photonic sensor system capable of sensing arterial wall movements of a few hundred microns in vivo with sub-micron resolution, a precision in the micrometer range and a temporal resolution of 10 kHz. The photonic measurement principle is based on transmission photoplethysmography with stretchable optoelectronic sensors applied directly to large systemic arteries. The presented photonic sensor system expands the toolbox of cardiovascular measurement techniques and makes these key vital parameters continuously accessible over the long-term. In the near term, this new approach offers a tool for clinical research, and as a perspective, a continuous long-term monitoring system that enables novel diagnostic methods in arteriosclerosis and hypertension research that follow the trend in quantifying cardiovascular diseases by measuring arterial stiffness and more generally analyzing pulse contours.

  4. Arterial Distensibility in Chronic Inflammatory Rheumatic Disorders

    PubMed Central

    Yildiz, Mustafa

    2010-01-01

    The pulse wave velocity (PWV), as an indicator of arterial distensibility, may play an important role in the stratification of patients based on the cardiovascular risk. PWV inversely correlates with arterial distensibility and relative arterial compliance. Decreased arterial distensibility alters arterial blood pressure and flow dynamics, and disturbes coronary perfusion. Systemic immune and inflammatory diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are associated with increased morbidity and mortality, predominantly due to adverse cardiovascular events. Systemic inflammation in these disorders may alter arterial compliance and arterial distensibility and, through this effect, lead to accelerated atherosclerosis. We have demonstrated an increase in the carotid-femoral (aortic) PWV that is a technique in which large artery elasticity is assessed from analysis of the peripheral arterial waveform, in patients with chronic inflammatory conditions such as RA, SLE, familial Mediterranean fever (FMF), Wegener’s granulomatosis (WG), sarcoidosis, psoriasis and psoriatic arthritis except Behçet’s disease (BD). In this review, the issue of arterial stiffness in RA, SLE, as well as WG, psoriasis, FMF, BD, sarcoidosis, systemic sclerosis (SS) and Takayasu's arteritis (TA) is overviewed. PMID:20461114

  5. Increased distensibility in dependent veins following prolonged bedrest.

    PubMed

    Kölegård, Roger; Mekjavic, Igor B; Eiken, Ola

    2009-07-01

    Displacement of blood to the lower portion of the body that follows a postural transition from recumbent to erect is augmented by a prolonged period of recumbency (bedrest). Information is scarce as to what extent this augmented blood-volume shift to dependent veins is attributable to increased distensibility of the veins. Accordingly, we studied the effect of 5 weeks of horizontal bedrest on the pressure-distension relationship in limb veins. Elevation of venous distending pressure was induced by exposure of the body except the tested limb to supra-atmospheric pressure with the subject seated in a pressure chamber with one arm, or supine with a lower leg, protruding through a hole in the chamber door. Diameter changes in response to an increase of intravenous pressure (distensibility) from 60 to about 140 mmHg were measured in the brachial and posterior tibial veins using ultrasonographic techniques. Prior to bedrest, the distensibility was substantially less in the tibial than in the brachial vein. Bedrest increased (P < 0.01) pressure distension in the tibial vein by 86% from 7 +/- 3% before to 13 +/- 3% after bedrest. In the brachial vein, bedrest increased (P < 0.05) pressure distension by 36% from 14 +/- 5% before to 19 +/- 5% after bedrest. Thus, removal of the gravity-dependent pressure components that act along the blood vessels in erect posture increases the distensibility of dependent veins.

  6. Rapid response gas injection technique.

    PubMed

    Komar, J J

    1978-10-01

    A unique gas injection technique has been developed which has rapid response and is capable of supplying gas flowrates up to 5 kg/s at pressures of 3.45 x 10(6) N/m(2). Rise times to equilibrium pressure varied from 7 to 15 ms over the operating range. The reliability, excellent repeatibility, and uniform pressure have shown the system to be superior to previously utilized expansion tube gas injection techniques associated with very short duration impulse test facilities. The achievement of precise timing control of the valve opening permitted a complex electronic sequencing of facility events. An additional feature of automatic gas supply shut-off resulted in significant cost savings when rare gases were used as injectants. PMID:18698978

  7. Abdominal Distension and Vascular Collapse.

    PubMed

    Cosentino, Gina; Uwaifo, Gabriel I

    2016-04-01

    We present the case of a 43-year-old gentleman who presented to the emergency room with acute abdominal distension, confusion and vascular collapse. The emergent radiologic imaging obtained showed massive bilateral adrenal enlargement, but despite the initial clinical suspicion of possible overwhelming sepsis and/or massive abdominal/intralesional hemorrhage, lab tests based obtained rapidly confirmed the diagnosis of acute Addisonian crisis which responded dramatically to adrenocorticoid hormone replacement therapy and aggressive fluid resuscitation. The patient's established history of metastatic lung cancer confirmed this as a case of metastatic massive bilateral adrenal metastases with an initial presentation of acute adrenal insufficiency which is uncommon in the setting of metastatic carcinomatosis but more typically associated with lymphomas. Recognition of this clinical possibility is vital to enable rapid diagnosis and consequent life saving therapy. PMID:27328473

  8. Radioactive-gas separation technique

    NASA Technical Reports Server (NTRS)

    Haney, R.; King, K. J.; Nellis, D. O.; Nisson, R. S.; Robling, P.; Womack, W.

    1977-01-01

    Cryogenic technique recovers gases inexpensively. Method uses differences in vapor pressures, melting points, and boiling points of components in gaseous mixture. Series of temperature and pressure variations converts gases independently to solid and liquid states, thereby simplifying separation. Apparatus uses readily available cryogen and does not require expensive refrigeration equipment.

  9. Neurohumoral inhibitory mechanism initiated by antral distension.

    PubMed Central

    Yamagishi, T; Debas, H T

    1981-01-01

    This study examines the effect of graded antral distension with acid (0.1 M HCl) or alkali (0.1 M NaHCO3) on pentagastrin-stimulated acid secretion in two groups of dogs. Group A consisted of six dogs provided with innervated antral pouch. In these dogs, the vagal branches to the fundus, as well as the extragastric vagal divisions (hepatic and celiac), were preserved. All of these animals had a gastric fistula in the main stomach, and in two a denervated fundic pouch or Heidenhain pouch was constructed in addition. Group B consisted of four dogs with an innervated antral pouch and gastric fistula. In this latter group, however, parietal cell vagotomy as well as extragastric vagotomy (division of the hepatic and celiac branches) was performed so that the only vagal communication was between the antrum and the CNS. Antral distension with acid caused significant inhibition of pentagastrin-stimulated acid secretion from both the gastric fistula and the Heidenhain pouch in Group A dogs. Antral acidification without distension did not inhibit. Alkaline antral distension in this group caused much less inhibition of acid secretion, but did cause significant increase in circulating immunoreactive gastrin. In Group B dogs, antral distension with neither acid nor alkali caused inhibition of pentagastrin-stimulated acid secretion, indicating that intact vagal supply to the oxyntic mucosa and/or to the extragastric abdominal organs is necessary for the inhibitory mechanism to operate. The results of this study suggest that: a) antral acidification per se does not inhibit pentagastrin-stimulated acid secretion; and b) antral distension with acid, and to a lesser extent with alkali, is inhibitory only if vagal innervation to the fundus and other abdominal viscera is preserved. The observations are compatible with the hypothesis that antral distension activates a neurohumoral inhibitory mechanism releasing the inhibitor reflexly from sites other than the antrum or CNS. PMID

  10. New technique for calibrating hydrocarbon gas flowmeters

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Puster, R. L.

    1984-01-01

    A technique for measuring calibration correction factors for hydrocarbon mass flowmeters is described. It is based on the Nernst theorem for matching the partial pressure of oxygen in the combustion products of the test hydrocarbon, burned in oxygen-enriched air, with that in normal air. It is applied to a widely used type of commercial thermal mass flowmeter for a number of hydrocarbons. The calibration correction factors measured using this technique are in good agreement with the values obtained by other independent procedures. The technique is successfully applied to the measurement of differences as low as one percent of the effective hydrocarbon content of the natural gas test samples.

  11. Esophagogastric junction distensibility in hiatus hernia.

    PubMed

    Lottrup, C; McMahon, B P; Ejstrud, P; Ostapiuk, M A; Funch-Jensen, P; Drewes, A M

    2016-07-01

    Hiatus hernia is known to be an important risk factor for developing gastroesophageal reflux disease. We aimed to use the endoscopic functional lumen imaging probe (EndoFLIP) to evaluate the functional properties of the esophagogastric junction. EndoFLIP assessments were made in 30 patients with hiatus hernia and Barrett's esophagus, and in 14 healthy controls. The EndoFLIP was placed straddling the esophagogastric junction and the bag distended stepwise to 50 mL. Cross-sectional areas of the bag and intra-bag pressures were recorded continuously. Measurements were made in the separate sphincter components and hiatus hernia cavity. EndoFLIP measured functional aspects such as sphincter distensibility and pressure of all esophagogastric junction components and visualized all hiatus hernia present at endoscopy. The lower esophageal sphincter in hiatus hernia patients had a lower pressure (e.g. 47.7 ± 13.0 vs. 61.4 ± 19.2 mm Hg at 50-mL distension volume) and was more distensible (all P < 0.001) than the common esophagogastric junction in controls. In hiatus hernia patients, the crural diaphragm had a lower pressure (e.g. 29.6 ± 10.1 vs. 47.7 ± 13.0 mm Hg at 50-mL distension volume) and was more distensible (all P < 0.001) than the lower esophageal sphincter. There was a significant association between symptom scores in patients and EndoFLIP assessment. Conclusively, EndoFLIP was a useful tool. To evaluate the presence of a hiatus hernia and to measure the functional properties of the esophagogastric junction. Furthermore, EndoFLIP distinguished the separate esophagogastric junction components in hiatus hernia patients, and may help us understand the biomechanics of the esophagogastric junction and the mechanisms behind hiatal herniation. PMID:25789842

  12. Uterine distension differentially affects remodelling and distensibility of the uterine vasculature in non-pregnant rats.

    PubMed

    Osol, George; Barron, Carolyn; Mandalà, Maurizio

    2012-01-01

    During pregnancy the mammalian uterine circulation undergoes significant expansive remodelling necessary for normal pregnancy outcome. The underlying mechanisms are poorly defined. The goal of this study was to test the hypothesis that myometrial stretch actively stimulates uterine vascular remodelling by developing a new surgical approach to induce unilateral uterine distension in non-pregnant rats. Three weeks after surgery, which consisted of an infusion of medical-grade silicone into the uterine lumen, main and mesometrial uterine artery and vein length, diameter and distensibility were recorded. Radial artery diameter, distensibility and vascular smooth muscle mitotic rate (Ki67 staining) were also measured. Unilateral uterine distension resulted in significant increases in the length of main uterine artery and vein and mesometrial segments but had no effect on vessel diameter or distensibility. In contrast, there were significant increases in the diameter of the radial arteries associated with the distended uterus. These changes were accompanied by reduced arterial distensibility and increased vascular muscle hyperplasia. In summary, this is the first report to show that myometrial stretch is a sufficient stimulus to induce significant remodelling of uterine vessels in non-pregnant rats. Moreover, the results indicate differential regulation of these growth processes as a function of vessel size and type.

  13. Pathologic aerophagia: a rare cause of chronic abdominal distension

    PubMed Central

    de Jesus, Lisieux Eyer; Cestari, Ana Beatriz C.S.S.; da Silva, Orli Carvalho; Fernandes, Marcia Antunes; Firme, Livia Honorato

    2015-01-01

    Objective: To describe an adolescent with pathologic aerophagia, a rare condition caused by excessive and inappropriate swallowing of air and to review its treatment and differential diagnoses. Case description: An 11-year-old mentally impaired blind girl presenting serious behavior problems and severe developmental delay with abdominal distension from the last 8 months. Her past history included a Nissen fundoplication. Abdominal CT and abdominal radiographs showed diffuse gas distension of the small bowel and colon. Hirschsprung's disease was excluded. The distention was minimal at the moment the child awoke and maximal at evening, and persisted after control of constipation. Audible repetitive and frequent movements of air swallowing were observed. The diagnosis of pathologic aerophagia associated to obsessive-compulsive disorder and developmental delay was made, but pharmacological treatment was unsuccessful. The patient was submitted to an endoscopic gastrostomy, permanently opened and elevated relative to the stomach. The distention was resolved, while maintaining oral nutrition. Comments: Pathologic aerophagia is a rare self-limiting condition in normal children exposed to high levels of stress and may be a persisting problem in children with psychiatric or neurologic disease. In this last group, the disease may cause serious complications. Pharmacological and behavioral treatments are ill-defined. Severe cases may demand surgical strategies, mainly decompressive gastrostomy. PMID:26100594

  14. Laboratory Testing of Volcanic Gas Sampling Techniques

    NASA Astrophysics Data System (ADS)

    Kress, V. C.; Green, R.; Ortiz, M.; Delmelle, P.; Fischer, T.

    2003-12-01

    results suggest that they are poor recorders of gas composition. Filter pack methods are somewhat better, but are more difficult to interpret than previously recognized. We suggest several refinements to the filter-pack technique that can improve accuracy. Giggenbach bottles remain the best method for volcanic gas sampling, despite the inherent difficulty and danger of obtaining samples in active volcanic environments. Relative merits of different alkali solutions and indicators are discussed.

  15. Hydrocarbon radical thermochemistry: Gas-phase ion chemistry techniques

    SciTech Connect

    Ervin, Kent M.

    2014-03-21

    Final Scientific/Technical Report for the project "Hydrocarbon Radical Thermochemistry: Gas-Phase Ion Chemistry Techniques." The objective of this project is to exploit gas-phase ion chemistry techniques for determination of thermochemical values for neutral hydrocarbon radicals of importance in combustion kinetics.

  16. Management Strategies for Abdominal Bloating and Distension

    PubMed Central

    Foley, Anna; Burgell, Rebecca; Barrett, Jacqueline S.

    2014-01-01

    Bloating and distension are among the most common gastrointestinal complaints reported by patients with functional gut disorders and by the general population. These 2 complaints are also among the most prevalent of the severe symptoms reported by patients with irritable bowel syndrome. Nonetheless, only a limited number of published studies have specifically addressed bloating; it is infrequently studied as a primary endpoint, and what little systematic information exists has often been garnered from the assessment of secondary endpoints or the dissection of composite endpoints. This lack of data, and our consequent limited understanding of the pathophysiology of bloating, had hampered the quest for effective and targeted therapies until recently. Advances in the knowledge of underlying mechanisms, particularly with regard to the roles of diet, poorly absorbed fermentable carbohydrates, dysbiosis of the gut bacteria, alterations in visceral hypersensitivity, and abnormal viscerosomatic reflexes, have enabled the development of improved treatment options. The most significant recent advance has been a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which significantly reduces patients’ symptoms and improves quality of life. Given the prevalence of bloating and its perceived severity, it is clear that further studies regarding the pathogenesis and treatment of this problem are needed. PMID:27551250

  17. Technique for Measuring Gas Conversion Factors

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Sprinkle, D. R.

    1986-01-01

    Technique for measuring calibration conversion factors for hydrocarbon mass flowmeters applied to widely used type of commercial thermal mass flowmeter for hydrocarbon gases. Values of conversion factors for two common hydrocarbons measured using this technique in good agreement with empirical values cited by manufacturer. Similar agreement expected for all other hydrocarbons. Technique based on Nernst theorem for matching partial pressure of oxygen in combustion product gases with that in normal air. Simple, quick, and relatively safe, particularly for toxic/poisonous hydrocarbons.

  18. A new technique for pumping hydrogen gas

    USGS Publications Warehouse

    Friedman, I.; Hardcastle, K.

    1970-01-01

    A system for pumping hydrogen gas without isotopic fractionation has been developed. The pump contains uranium metal, which when heated to about 80??C reacts with hydrogen to form UH3. The UH3 is heated to above 500??C to decompose the hydride and regenerate the hydrogen. ?? 1970.

  19. Aortic stiffness and distensibility among hypertensives.

    PubMed

    Meenakshisundaram, R; Kamaraj, K; Murugan, S; Thirumalaikolundusubramanian, P

    2009-09-01

    Hypertension is one among many factors that contribute to aortic stiffness, which has repercussions mainly on the heart. To assess aortic stiffness among essential hypertensives of South India and its relationship with gender. An analytical study was designed to assess aortic stiffness among 60 nonobese, nonalcoholic, nonsmoking, and non-caffeine consuming essential hypertensives without any overt illness or infection, and compared with 30 healthy age- and sex-matched nonhypertensives. They were assessed clinically and also by laboratory means. Their left ventricular mass (LV) and left ventricular ejection fraction (LVEF) were measured using Transthoracic echocardiogram. Aortic systolic and diastolic diameters were measured by using M-mode echocardiography during consecutive beats and averaged for each case. Finally, aortic stiffness was calculated. The data were analyzed statistically. Hypertensives were divided into Group I, consisting of patients with hypertension at least for 5 years, who were not adherent to medication, and Group II, consisting of patients with hypertension of duration between 6 months and 1 year. There were 20 males and 10 females in each group. There was no significant difference between the hypertensive groups and a control, normotensive, group with regard to BMI or total cholesterol. The means of LV mass (in grams), systolic BP (in mmHg), diastolic BP (in mmHg), aortic systolic diameter (in mm), aortic diastolic diameter (in mm), aortic distensibility (in mm), and aortic stiffness found in Group I, Group II, and controls were 105.8 +/- 23.8, 101.5 +/- 21, and 84 +/- 9.8; 138 +/- 14.2, 153 +/- 17.1, and 120 +/- 8.3; 90.5 +/- 11.6, 101.7 +/- 17.1, and 76.5 +/- 5; 30.85 +/- 2.6, 28.7 +/- 2.6, and 27.7 +/- 2.4; 28.7 +/- 2.2, 25.8 +/- 2.5, and 24.2 +/- 2.5; 2.14 +/- 0.3, 2.84 +/- 0.5, and 3.5 +/- 0.6; and 1.31 +/- 0.09, 1.14 +/- 0.1, and 1.04 +/- 0.08, respectively. The differences between the hypertensive groups and the control group were

  20. Quantification of pulmonary arterial wall distensibility using parameters extracted from volumetric micro-CT images

    NASA Astrophysics Data System (ADS)

    Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Dawson, Christopher A.

    1999-09-01

    Stiffening, or loss of distensibility, of arterial vessel walls is among the manifestations of a number of vascular diseases including pulmonary arterial hypertension. We are attempting to quantify the mechanical properties of vessel walls of the pulmonary arterial tree using parameters derived from high-resolution volumetric x-ray CT images of rat lungs. The pulmonary arterial trees of the excised lungs are filled with a contrast agent. The lungs are imaged with arterial pressures spanning the physiological range. Vessel segment diameters are measured from the inlet to the periphery, and distensibilities calculated from diameters as a function of pressure. The method shows promise as an adjunct to other morphometric techniques such as histology and corrosion casting. It possesses the advantages of being nondestructive, characterizing the vascular structures while the lungs are imaged rapidly and in a near-physiological state, and providing the ability to associate mechanical properties with vessel location in the intact tree hierarchy.

  1. Hyperpolarized Gas MRI: Technique and Applications

    PubMed Central

    McAdams, Holman P.; Kaushik, S. Sivaram; Driehuys, Bastiaan

    2015-01-01

    Synopsis Functional imaging today offers a rich world of information that is more sensitive to changes in lung structure and function than traditionally obtained pulmonary function tests. Hyperpolarized helium (3He) and xenon (129Xe) MR imaging of the lungs provided new sensitive contrast mechanisms to probe changes in pulmonary ventilation, microstructure and gas exchange. With the recent scarcity in the supply of 3He the field of hyperpolarized gas imaging shifted to the use of cheaper and naturally available 129Xe. Xenon is well tolerated and recent technical advances have ensured that the 129Xe image quality is on par with that of 3He. The added advantage of 129Xe is its solubility in pulmonary tissue, which allows exploring specific lung function characteristics involved in gas exchange and alveolar oxygenation. With a plethora of contrast mechanisms, hyperpolarized gases and 129Xe in particular, stands to be an excellent probe of pulmonary structure and function, and provide sensitive and non-invasive biomarkers for a wide variety of pulmonary diseases. PMID:25952516

  2. GAS CHROMATOGRAPHIC TECHNIQUES FOR THE MEASUREMENT OF ISOPRENE IN AIR

    EPA Science Inventory

    The chapter discusses gas chromatographic techniques for measuring isoprene in air. Such measurement basically consists of three parts: (1) collection of sufficient sample volume for representative and accurate quantitation, (2) separation (if necessary) of isoprene from interfer...

  3. Technique for measuring gas conversion factors

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Sprinkle, D. R. (Inventor)

    1985-01-01

    A method for determining hydrocarbon conversion factors for a flowmeter. A mixture of air, O2 and C sub x H sub y is burned and the partial paressure of O2 in the resulting gas is forced to equal the partial pressure of O2 in air. The flowrate of O2 flowing into the mixture is measured by flowmeter and the flowrate of C sub x H sub y flowing into the mixture is measured by the flowmeter conversion factor is to be determined. These measured values are used to calculate the conversion factor.

  4. A Precise Calibration Technique for Measuring High Gas Temperatures

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.; Schultz, Donald F.

    1999-01-01

    A technique was developed for direct measurement of gas temperatures in the range of 2050 K - 2700 K with improved accuracy and reproducibility. The technique utilized the low-emittance of certain fibrous Materials, and the uncertainty of the technique was limited by the uncertainty in the melting points of the materials, i.e., +/- 15 K. The materials were pure, thin, metal-oxide fibers whose diameters varied from 60 mm to 400 mm in the experiments. The sharp increase in the emittance of the fibers upon melting was utilized as indication of reaching a known gas temperature. The accuracy of the technique was confirmed by both calculated low emittance values of transparent fibers, of order 0.01, up to a few degrees below their melting point and by the fiber-diameter independence of the results. This melting-point temperature was approached by increments not larger than 4 K, which was accomplished by controlled increases of reactant flow rates in hydrogen-air and/or hydrogen- oxygen flames. As examples of the applications of the technique, the gas-temperature measurements were used (a) for assessing the uncertainty in infering gas temperatures from thermocouple measurements, and (b) for calibrating an IR camera to measure gas temperatures. The technique offers an excellent calibration reference for other gas-temperature measurement methods to improve their accuracy and reliably extending their temperature range of applicability.

  5. A Precise Calibration Technique for Measuring High Gas Temperatures

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.; Schultz, Donald F.

    2000-01-01

    A technique was developed for direct measurement of gas temperatures in the range of 2050 K 2700 K with improved accuracy and reproducibility. The technique utilized the low-emittance of certain fibrous materials, and the uncertainty of the technique was United by the uncertainty in the melting points of the materials, i.e., +/-15 K. The materials were pure, thin, metal-oxide fibers whose diameters varied from 60 microns to 400 microns in the experiments. The sharp increase in the emittance of the fibers upon melting was utilized as indication of reaching a known gas temperature. The accuracy of the technique was confirmed by both calculated low emittance values of transparent fibers, of order 0.01, up to a few degrees below their melting point and by the fiber-diameter independence of the results. This melting-point temperature was approached by increments not larger than 4 K, which was accomplished by controlled increases of reactant flow rates in hydrogen-air and/or hydrogen-oxygen flames. As examples of the applications of the technique, the gas-temperature measurements were used: (a) for assessing the uncertainty in inferring gas temperatures from thermocouple measurements, and (b) for calibrating an IR camera to measure gas temperatures. The technique offers an excellent calibration reference for other gas-temperature measurement methods to improve their accuracy and reliably extending their temperature range of applicability.

  6. Ethylene Trace-gas Techniques for High-speed Flows

    NASA Technical Reports Server (NTRS)

    Davis, David O.; Reichert, Bruce A.

    1994-01-01

    Three applications of the ethylene trace-gas technique to high-speed flows are described: flow-field tracking, air-to-air mixing, and bleed mass-flow measurement. The technique involves injecting a non-reacting gas (ethylene) into the flow field and measuring the concentration distribution in a downstream plane. From the distributions, information about flow development, mixing, and mass-flow rates can be dtermined. The trace-gas apparatus and special considerations for use in high-speed flow are discussed. A description of each application, including uncertainty estimates is followed by a demonstrative example.

  7. Feasibility of esophagogastric junction distensibility measurement during Nissen fundoplication.

    PubMed

    Ilczyszyn, A; Botha, A J

    2014-01-01

    Increased esophagogastric junction distensibility has been implicated in the development of gastroesophageal reflux disease (GERD). Previous authors have demonstrated a reduction in distensibility following anti-reflux surgery, but the changes during the operation are not clear. Our study aimed to ascertain the feasibility of measuring intraoperative distensibility changes and to assess if this would have potential to modify the operation. Seventeen patients with GERD were managed in a standardized manner consisting of preoperative assessment with symptom scoring, endoscopy, 24 hours pH studies, and manometry. Patients then underwent laparoscopic Nissen fundoplication with intraoperative distensibility measurement using an EndoFLIP EF-325 functional luminal imaging probe (Crospon Ltd, Galway, Ireland). This device utilizes impedance planimetry technology to measure cross-sectional area and distensibility within a balloon-tipped catheter. This is inflated at the esophagogastric junction to fixed distension volumes. Thirty-second median cross-sectional area and intraballoon pressure measurements were recorded at 30 and 40 mL balloon distensions. Measurement time points were initially after induction of anesthesia, after pneumoperitoneum, after hiatal mobilization, after hiatal repair, after fundoplication, and finally pre-extubation. Postoperatively, patients continued on protocol and were discharged after a two-night stay tolerating a sloppy diet. Patients with a hiatus hernia on high-resolution manometry had a significantly higher initial esophagogastric junction distensibility index (DI) than those without. Hiatus repair and fundoplication resulted in a significant overall reduction in the median DI from the initial to final recordings (30 mL balloon distension reduction of 3.26 mm(2) /mmHg (P = 0.0087), 40 mL balloon distension reduction of 2.39 mm(2) /mmHg [P = 0.0039]). There was also a significant reduction in the DI after pneumoperitoneum, hiatus

  8. Static gas analysis by a transient flow technique

    SciTech Connect

    Leckey, J.H.; Boeckmann, M.D.

    1988-07-01

    A technique is presented for using a residual gas analyzer (RGA) to analyze small concentrations of heavy gases in lighter gases in a static volume of <10 cm/sup 3/ . Passing the gas sample through a control valve causes it to enter the RGA chamber in molecular flow. This procedure results in fractionation that causes enrichment of the heavier gas during the evacuation of the sample, giving rise to a significantly higher heavy gas signal near the end of the evacuation, while maintaining low pressures in the RGA chamber that are required for linearity. This heavy gas enrichment near the end of the evacuation results in a significant reduction in its detection limit. Specific examples are presented for the analysis of argon in hydrogen and are compared to a gas-flow model of the system.

  9. Demonstration of landfill gas enhancement techniques in landfill simulators

    NASA Astrophysics Data System (ADS)

    Walsh, J. J.; Vogt, W. G.

    1982-02-01

    Various techniques to enhance gas production in sanitary landfills were applied to landfill simulators. These techniques include (1) accelerated moisture addition, (2) leachate recycling, (3) buffer addition, (4) nutrient addition, and (5) combinations of the above. Results are compiled through on-going operation and monitoring of sixteen landfill simulators. These test cells contain about 380 kg of municipal solid waste. Quantities of buffer and nutrient materials were placed in selected cells at the time of loading. Water is added to all test cells on a monthly basis; leachate is withdrawn from all cells (and recycled on selected cells) also on a monthly basis. Daily monitoring of gas volumes and refuse temperatures is performed. Gas and leachate samples are collected and analyzed on a monthly basis. Leachate and gas quality and quantity reslts are presented for the first 18 months of operation.

  10. The pathogenesis of bloating and visible distension in irritable bowel syndrome.

    PubMed

    Azpiroz, Fernando; Malagelada, Juan R

    2005-06-01

    Abdominal bloating is a relevant, troublesome, and poorly understood clinical problem. Despite its clinical importance, bloating remains substantially ignored, without proper clinical classification, known pathophysiology, and effective treatment. It is not even clear to what extent the complaints of individual patients correlate with objective evidence of abdominal distension, and this uncertainly regarding the subjective or objective origin of the complaints further adds to confusion. This article proposed a framework for investigating bloating, considering key factors potentially involved in its pathophysiology: distorted sensation, physical abdominal expansion, and abdominal wall dystony. Some data indicate that patients complaining of bloating have impaired transit and tolerance of intestinal gas loads. The problem does not seem to be too much gas,however, but rather abnormal responses to gas. Furthermore, abnormal control of abdominal muscle activity in these patients may contribute to objective distension. Bloating, like many other abdominal symptoms,probably represents a heterogeneous condition produced by a combination of pathophysiological mechanisms that differ among individual patients,resulting in a polymorphic clinical presentation.

  11. Arterial distensibility in children and teenagers: normal evolution and the effect of childhood vasculitis

    PubMed Central

    Cheung, Y; Brogan, P; Pilla, C; Dillon, M; Redington, A

    2002-01-01

    Background: Polyarteritis nodosa is a necrotising vasculitis of the medium sized and small muscular arteries. The inflammatory and subsequent reparative processes may alter the arterial mechanical properties. The effect of vasculitic damage on arterial distensibility has never been explored however. Aim: To determine the normal values and the effect of childhood vasculitis on arterial distensibility in children and teenagers. Methods: Distensibility of the brachioradial arterial segment was studied using pulse wave velocity (PWV ∝1/√distensibility), in 13 children with polyarteritis nodosa at a median age of 11.8 (range 4.9–16) years. As a control group, 155 healthy schoolchildren (6–18 years, 81 boys) were studied. PWV was assessed using a photoplethysmographic technique; blood pressure was measured by an automatic sphygmomanometer (Dinamap). Data from patients were expressed as z scores adjusted for age and compared to a population mean of 0 by a single sample t test. Determinants of PWV in normal children were assessed by univariate and multivariate linear regression analyses. Results: Age, height, weight, and systolic blood pressure correlated individually with the brachioradial PWV. Multivariate analysis identified age as the only independent determinant. Ten of the patients were in clinical remission, while three had evidence of disease activity at the time of study. The PWV in the patient group as a whole was significantly greater than those in healthy children (mean z score +0.99). Raised C reactive protein concentration (>2 mg/dl) in the three patients with active disease was associated with a higher PWV when compared to those in remission (z score +2.78 v +0.45). The diastolic blood pressure of the patients was higher than those of the controls (z score +1.04) while the systolic pressure was similar (z score -0.36). Conclusions: PWV in the brachioradial arterial segment increases gradually during childhood independent of body weight, height, mass

  12. Automated measurement of respiratory gas exchange by an inert gas dilution technique

    NASA Technical Reports Server (NTRS)

    Sawin, C. F.; Rummel, J. A.; Michel, E. L.

    1974-01-01

    A respiratory gas analyzer (RGA) has been developed wherein a mass spectrometer is the sole transducer required for measurement of respiratory gas exchange. The mass spectrometer maintains all signals in absolute phase relationships, precluding the need to synchronize flow and gas composition as required in other systems. The RGA system was evaluated by comparison with the Douglas bag technique. The RGA system established the feasibility of the inert gas dilution method for measuring breath-by-breath respiratory gas exchange. This breath-by-breath analytical capability permits detailed study of transient respiratory responses to exercise.

  13. Vessel distensibility and flow distribution in vascular trees.

    PubMed

    Krenz, Gary S; Dawson, Christopher A

    2002-04-01

    In a class of model vascular trees having distensible blood vessels, we prove that flow partitioning throughout the tree remains constant, independent of the nonzero driving flow (or nonzero inlet to terminal outlet pressure difference). Underlying assumptions are: (1) every vessel in the tree exhibits the same distensibility relationship given by D/D(0) = f(P) where D is the diameter which results from distending pressure P and D(0) is the diameter of the individual vessel at zero pressure (each vessel may have its own individual D(0). The choice of f(P) includes distensibilities often used in vessel biomechanics modeling, e.g., f(P) = 1 + alpha P or f(P) = b + (1-b) exp(-c P), as well as f(P) which exhibit autoregulatory behavior. (2) Every terminal vessel in the tree is subjected to the same terminal outlet pressure. (3) Bernoulli effects are ignored. (4) Flow is nonpulsatile. (5) Blood viscosity within any individual vessel is constant. The results imply that for a vascular tree consistent with assumptions 2-5, the flow distribution calculations based on a rigid geometry, e.g., D=D(0), also gives the flow distribution when assuming the common distensibility relationships.

  14. [Start of mastication by esophageal distension in sheep].

    PubMed

    Boivin, R; Bost, J; Peralta, F E

    1985-01-01

    Oesophageal wall distension was performed on standing conscious sheep by inflating a rubber balloon at four different levels inside the cervical and thoracic oesophagus. Although no retrograde oesophageal peristalsis was ever recorded, these stimulations were always followed by a conspicuous increase of parotid saliva secretion. They frequently induced the onset of chewing movements, whatever the level of the oesophageal distension. The cyclical reticular activity does not bear any relationship to the occurrence of the chewing movements. The masticatory response could be either of the "ON" or "ON - OFF" type, but most often of the "OFF" type. The response to thoracic oesophageal distension was suppressed by mid-cervical anaesthetic blockage of vagal conduction. A possible involvement of any sort of stimulation of the oral cavity was thus ruled out. The masticatory response to oesophageal distension is a reflex mechanism whose afferent pathway from the distal part lies in the vagal trunk. Such a reflex may participate early in the initiation of chewing movements during rumination, prior to the arrival of the regurgitated bolus into the mouth.

  15. Inverse-dispersion technique for assessing lagoon gas emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measuring gas emissions from treatment lagoons and storage ponds poses challenging conditions for existing micrometeorological techniques because of non-ideal wind conditions, such as those induced by trees and crops surrounding the lagoons, and lagoons with dimensions too small to establish equilib...

  16. Dynamic technique for measuring adsorption in a gas chromatograph

    NASA Technical Reports Server (NTRS)

    Deuel, C. L.; Hultgren, N. W.; Mobert, M. L.

    1973-01-01

    Gas-chromatographic procedure, together with mathematical analysis of adsorption isotherm, allows relative surface areas and adsorptive powers for trace concentrations to be determined in a few minutes. Technique may be used to evaluate relative surface areas of different adsorbates, expressed as volume of adsorbent/gram of adsorbate, and to evaluate their relative adsorptive power.

  17. Extended electrode technique. [gas metal arc welding of metal plates

    NASA Technical Reports Server (NTRS)

    Schaper, V. D.; Pollack, A.

    1972-01-01

    The extended electrode technique is a unique welding process which utilizes manual gas-metal-arc (GMAW) semi-automatic equipment and close, square butt joints to effectively produce a weld. The technique takes advantage of the resistance heating of the electode extension to effect the root pass. Weldments as large as 72-X30-X2-inch have been fabricated with this technique under normal shipyard welding conditions. Mechanical properties and explosion bulge tests indicate that satisfactory results are obtained with this process. Potential savings of approximately 50 percent can be achieved in flat welding and repair of heavy structural steel members.

  18. Practical Techniques for Modeling Gas Turbine Engine Performance

    NASA Technical Reports Server (NTRS)

    Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Jonathan S.

    2016-01-01

    The cost and risk associated with the design and operation of gas turbine engine systems has led to an increasing dependence on mathematical models. In this paper, the fundamentals of engine simulation will be reviewed, an example performance analysis will be performed, and relationships useful for engine control system development will be highlighted. The focus will be on thermodynamic modeling utilizing techniques common in industry, such as: the Brayton cycle, component performance maps, map scaling, and design point criteria generation. In general, these topics will be viewed from the standpoint of an example turbojet engine model; however, demonstrated concepts may be adapted to other gas turbine systems, such as gas generators, marine engines, or high bypass aircraft engines. The purpose of this paper is to provide an example of gas turbine model generation and system performance analysis for educational uses, such as curriculum creation or student reference.

  19. Alternative control techniques document. NOx emissions from stationary gas turbines

    SciTech Connect

    Snyder, R.B.

    1993-01-01

    The Alternative Control Techniques document describes available control technologies for reducing NOx emissions levels from stationary combustion gas turbines. Information on the formation of NOx and uncontrolled NOx emissions from gas turbines is included. Water injection, steam injection, and low-NOx combustors, used independently or in combination with selective catalytic reduction (SCR), are discussed. Achievable controlled NOx emissions levels, costs and cost effectiveness, and environmental impacts are presented and applicability to new equipment as well as retrofit applications is discussed. The application of these technologies to gas turbines operating in offshore platform applications is included. Information on the use of alternate fuels, catalytic combustion, and selective noncatalytic reduction (SNCR) to reduce NOx emissions is also briefly presented.

  20. Soil Gas Surveys: A cost-effective site assessment technique

    SciTech Connect

    Barker, G.W.; Brown, D.R.; Corgan, J.M.

    1995-12-01

    Accurate delineation of the extent of subsurface hydrocarbon contamination in soils and ground water is important when initiating a monitoring plan or considering remediation options at E&P sites. Traditional site-assessment techniques used to delineate subsurface hydrocarbon contaminants (e.g., soil boreholes, excavation, monitor well installation, etc.) can be expensive, time-consuming, and disruptive to local land use or production operations. Soil gas surveys can provide a rapid, cost-effective, nonobtrusive alternative to traditional site-assessment techniques.

  1. Advanced liner-cooling techniques for gas turbine combustors

    NASA Technical Reports Server (NTRS)

    Norgren, C. T.; Riddlebaugh, S. M.

    1985-01-01

    Component research for advanced small gas turbine engines is currently underway at the NASA Lewis Research Center. As part of this program, a basic reverse-flow combustor geometry was being maintained while different advanced liner wall cooling techniques were investigated. Performance and liner cooling effectiveness of the experimental combustor configuration featuring counter-flow film-cooled panels is presented and compared with two previously reported combustors featuring: splash film-cooled liner walls; and transpiration cooled liner walls (Lamilloy).

  2. Mechanism of UES relaxation initiated by gastric air distension.

    PubMed

    Lang, Ivan M; Medda, Bidyut K; Shaker, Reza

    2014-08-15

    The aim of this study was to determine the mechanism of initiation of transient upper esophageal sphincter relaxation (TUESR) caused by gastric air distension. Cats (n = 31) were decerebrated, EMG electrodes were placed on the cricopharyngeus, a gastric fistula was formed, and a strain gauge was sewn on the lower esophageal sphincter (n = 8). Injection of air (114 ± 13 ml) in the stomach caused TUESR (n = 18) and transient lower esophageal sphincter relaxation (TLESR, n = 6), and this effect was not significantly (P > 0.05) affected by thoracotomy. Free air or bagged air (n = 6) activated TLESR, but only free air activated TUESR. Closure of the gastroesophageal junction blocked TUESR (9/9), but not TLESR (4/4), caused by air inflation of the stomach. Venting air from distal esophagus during air inflation of the stomach prevented TUESR (n = 12) but did not prevent air escape from the stomach to the esophagus (n = 4). Rapid injection of air on the esophageal mucosa always caused TUESR (9/9) but did not always (7/9) cause an increase in esophageal pressure. The time delay between the TUESR and the rapid air pulse was significantly more variable (P < 0.05) than the time delay between the rapid air pulse and the rise in esophageal pressure. We concluded that the TUESR caused by gastric air distension is dependent on air escape from the stomach, which stimulates receptors in the esophagus, but is not dependent on distension of the stomach or esophagus, or the TLESR. Therefore, the TUESR caused by gastric air distension is initiated by stimulation of receptors in the esophageal mucosa.

  3. Transitional Flow in an Arteriovenous Fistula: Effect of Wall Distensibility

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Aliseda, Alberto

    2012-11-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis in patients with end-stage renal disease. Transitional flow and the subsequent pressure and shear stress fluctuations are thought to be causative in the fistula failure. Since 50% of fistulae require surgical intervention before year one, understanding the altered hemodynamic stresses is an important step toward improving clinical outcomes. We perform numerical simulations of a patient-specific model of a functioning fistula reconstructed from 3D ultrasound scans. Rigid wall simulations and fluid-structure interaction simulations using an in-house finite element solver for the wall deformations were performed and compared. In both the rigid and distensible wall cases, transitional flow is computed in fistula as evidenced by aperiodic high frequency velocity and pressure fluctuations. The spectrum of the fluctuations is much more narrow-banded in the distensible case, however, suggesting a partial stabilizing effect by the vessel elasticity. As a result, the distensible wall simulations predict shear stresses that are systematically 10-30% lower than the rigid cases. We propose a possible mechanism for stabilization involving the phase lag in the fluid work needed to deform the vessel wall. Support from an NIDDK R21 - DK08-1823.

  4. Combined biological and physicochemical waste-gas cleaning techniques.

    PubMed

    Rene, Eldon R; Veiga, María C; Kennes, Christian

    2012-01-01

    This review presents a general overview of physical, chemical and biological waste-gas treatment techniques such as adsorption, absorption, oxidation and biodegradation, focusing more extensively on combined processes. It is widely recognized that biological waste-gas treatment devices such as biofilters and biotrickling filters can show high performance, often reaching removal efficiencies above 90 % for pollutant concentrations below 5 g/m(3). However, for concentrations exceeding this limit and under transient shock-load conditions that are frequently encountered in industrial situations, a physicochemical gas cleaning process can sometimes be advantageously combined with a biological one. Besides improving the overall treatment efficiency, the non-biological, first-stage process could also serve as a load equalization system by reducing the pollutant load during periodic shock-loads, to levels that can easily be handled in the second-stage bioreactor. This article reviews the operational advantages of integrating different non-biological and biological processes, i.e., adsorption pre-treatment+bioreactor, bioreactor+adsorption post-treatment, absorption pre-treatment+bioreactor, UV pre-treatment+bioreactor, and bioreactor/bioreactor combinations, for waste-gas treatment, where different gas-phase pollutants have been tested.

  5. Does Measurement of Esophagogastric Junction Distensibility by EndoFLIP Predict Therapy-responsiveness to Endoluminal Fundoplication in Patients With Gastroesophageal Reflux Disease?

    PubMed Central

    Smeets, Fabiënne G M; Keszthelyi, Daniel; Bouvy, Nicole D; Masclee, Ad A M; Conchillo, José M

    2015-01-01

    Background/Aims In patients with gastroesophageal reflux disease (GERD), an increased esophagogastric junction (EGJ) distensibility has been described. Assessment of EGJ distensibility with the endoscopic functional luminal imaging probe (EndoFLIP) technique might identify patients responsive to transoral incisionless fundoplication (TIF), whereas postoperative measurement of EGJ distensibility might provide insight into the antireflux mechanism of TIF. Therefore, we investigated the value of the EndoFLIP technique in GERD patients treated by TIF. Methods Forty-two GERD patients underwent EGJ distensibility measurement before TIF using the EndoFLIP technique. In a subgroup of 25 patients, EndoFLIP measurement was repeated both postoperative and at 6 months follow-up. Treatment outcome was assessed according to esophageal acid exposure time (AET; objective outcome) and symptom scores (clinical outcome) 6 months after TIF. Results Multiple logistic regression analysis showed that preoperative EGJ distensibility (OR, 0.16; 95% CI, 0.03–0.78; P = 0.023) and preoperative AET (OR, 0.62; 95% CI, 0.42–0.90; P = 0.013) were independent predictors for objective treatment outcome but not for clinical outcome after TIF. The best cut-off value for objective outcome was 2.3 mm2/mmHg for preoperative EGJ distensibility and 11% for preoperative AET. EGJ distensibility decreased direct postoperative from 2.0 (1.2–3.3) to 1.4 (1.0–2.2) mm2/mmHg (P = 0.014), but increased to 2.2 (1.5–3.0) at 6 months follow-up (P = 0.925, compared to preoperative). Conclusions Preoperative EGJ distensibility and preoperative AET were independent predictors for objective treatment outcome but not for clinical outcome after TIF. According to our data, the EndoFLIP technique has no added value either in the preoperative diagnostic work-up or in the post-procedure evaluation of endoluminal antireflux therapy. PMID:25742904

  6. A novel technique for highly accurate gas exchange measurements

    NASA Astrophysics Data System (ADS)

    Kalkenings, R. K.; Jähne, B. J.

    2003-04-01

    The Heidelberg Aeolotron is a circular wind-wave facility for investigating air-sea gas exchange. In this contribution a novel technique for measuring highly accurate transfer velocities k of mass transfer will be presented. Traditionally, in mass balance techniques the constant of decay for gas concentrations over time is measured. The major drawback of this concept is the long time constant. At low wind speeds and a water height greater than 1 m the period of observation has to be several days. In a gas-tight facility such as the Aeolotron, the transfer velocity k can be computed from the concentration in the water body and the change of concentration in the gas space. Owing to this fact, transfer velocities are gained while greatly reducing the measuring times to less than one hour. The transfer velocity k of a tracer can be parameterized as k=1/β \\cdot u_* \\cdot Sc^n, with the Schmidt Number Sc, shear velocity u_* and the dimensionless transfer resistance β. The Schmidt Number exponent n can be derived from simultaneous measurements of different tracers. Since these tracers are of different Schmidt number, the shear velocity is not needed. To allow for Schmidt numbers spanning a hole decade, in our experiments He, H_2, N_2O and F12 are used. The relative accuracy of measuring the transfer velocity was improved to less than 2%. In 9 consecutive experiments conducted at a wind speed of 6.2 m/s, the deviation of the Schmidt number exponent was found to be just under 0.02. This high accuracy will allow precisely determining the transition of the Schmidt number exponent from n=2/3 to n=0.5 from a flat to wavy water surface. In order to quantify gas exchange not only the wind speed is important. Surfactants have a pronounced effect on the wave field and lead to a drastic reduction in the transfer velocity. In the Aeolotron measurements were conducted with a variety of measuring devices, ranging from an imaging slope gauge (ISG) to thermal techniques with IR

  7. Reflex control of intestinal gas dynamics and tolerance in humans.

    PubMed

    Harder, Hermann; Serra, Jordi; Azpiroz, Fernando; Malagelada, Juan-R

    2004-01-01

    Intestinal transit of gas is normally adapted to the luminal gas load, but in some patients impaired transit may lead to gas retention and symptoms. We hypothesized that intestinal gas transit is regulated by reflex mechanisms released by segmental distension at various gut levels. In 24 healthy subjects, we measured gas evacuation and perception of jejunal gas infusion (12 ml/min) during simultaneous infusion of duodenal lipids mimicking the postprandial caloric load (Intralipid, 1 kcal/min). We evaluated the effects of proximal (duodenal) distension (n = 8), distal (rectal) distension (n = 8), and sham distension, as control (n = 8). Duodenal lipid infusion produced gas retention (366 +/- 106 ml) with low abdominal perception (1.5 +/- 0.8 score). Distension of either the duodenum or rectum during lipid infusion expedited gas transit and prevented retention (-120 +/- 164 and -124 +/- 162 ml retention, respectively; P < 0.05 vs. control). However, the tolerance to the intestinal gas load differed markedly, depending on the site of distension; perception remained low during rectal distension (2.6 +/- 0.7 score; not significant vs. control) but increased during duodenal distension (4.4 +/- 0.7 score; P < 0.05 vs. control). We conclude that focal gut distension, either at proximal or distal sites, accelerates gas transit, but the symptomatic response depends on the site of stimulation.

  8. Unit vent airflow measurements using a tracer gas technique

    SciTech Connect

    Adams, D.G.; Lagus, P.L.; Fleming, K.M.

    1997-08-01

    An alternative method for assessing flowrates that does not depend on point measurements of air flow velocity is the constant tracer injection technique. In this method one injects a tracer gas at a constant rate into a duct and measures the resulting concentration downstream of the injection point. A simple equation derived from the conservation of mass allows calculation of the flowrate at the point of injection. Flowrate data obtained using both a pitot tube and a flow measuring station were compared with tracer gas flowrate measurements in the unit vent duct at the Callaway Nuclear Station during late 1995 and early 1996. These data are presented and discussed with an eye toward obtaining precise flowrate data for release rate calculations. The advantages and disadvantages of the technique are also described. In those test situations for which many flowrate combinations are required, or in large area ducts, a tracer flowrate determination requires fewer man-hours than does a conventional traverse-based technique and does not require knowledge of the duct area. 6 refs., 10 figs., 6 tabs.

  9. Noble Gas Measurement and Analysis Technique for Monitoring Reprocessing Facilities

    SciTech Connect

    Charlton, William S

    1999-09-01

    An environmental monitoring technique using analysis of stable noble gas isotopic ratios on-stack at a reprocessing facility was developed. This technique integrates existing technologies to strengthen safeguards at reprocessing facilities. The isotopic ratios are measured using a mass spectrometry system and are compared to a database of calculated isotopic ratios using a Bayesian data analysis method to determine specific fuel parameters (e.g., burnup, fuel type, fuel age, etc.). These inferred parameters can be used by investigators to verify operator declarations. A user-friendly software application (named NOVA) was developed for the application of this technique. NOVA included a Visual Basic user interface coupling a Bayesian data analysis procedure to a reactor physics database (calculated using the Monteburns 3.01 code system). The integrated system (mass spectrometry, reactor modeling, and data analysis) was validated using on-stack measurements during the reprocessing of target fuel from a U.S. production reactor and gas samples from the processing of EBR-II fast breeder reactor driver fuel. These measurements led to an inferred burnup that matched the declared burnup with sufficient accuracy and consistency for most safeguards applications. The NOVA code was also tested using numerous light water reactor measurements from the literature. NOVA was capable of accurately determining spent fuel type, burnup, and fuel age for these experimental results. Work should continue to demonstrate the robustness of this system for production, power, and research reactor fuels.

  10. Determination of membrane tension during balloon distension of intestine.

    PubMed

    Gregersen, H; Kassab, G S; Fung, Y C

    2004-09-01

    During the last decades, it has become increasingly common to make balloons distension in visceral organs in vivo. In particular this is true for studies of gastrointestinal motor function and biomechanics. Balloon distension is often used for assessment of small intestinal compliance and tension based on Laplace's law for cylindrical pressure pipes. This commonly used law is valid only when the balloon-distended intestine is cylindrical. Experimentally, it is seen that the diameter of the balloon-distended intestine is not a constant, but variable in the axial direction. Hence, it is necessary to improve Laplace's law for intestinal investigation. In this paper we develop the framework for determination of the tension distribution in circumferential and longitudinal direction during balloon distension. When the radii of curvature are measured from a photograph of the intestinal profile, then the membrane stress resultants can be computed everywhere in the intestine in contact with the balloon from the equations of equilibrium. The experimental data were obtained from small intestinal segments from five pigs and three guinea pigs. Papaverine was injected before the animals were sacrificed to relax the intestinal smooth muscle. The segments were immersed in a bath with calcium-free Krebs solution with dextran and EGTA. A balloon was distended in the lumen with pressures up to 15 cmH2O in the pigs and 10 cmH2O in the guinea pigs and radii were measured along the z-axis. The tension in circumferential direction had its maximum approximately 25% away from the middle of the balloon. The circumferential tension was 2-3 times higher than the longitudinal tension. In conclusion when we know the shape of the intestine, we can compute the circumferential and longitudinal components of tension. The large variation in tensions along the z axis must be considered when performing balloon distension studies in the gastrointestinal tract for studying physiological and

  11. TRIDENT flyer plate Impact technique: comparison to gas gun plate impact technique

    SciTech Connect

    Koller, Darcie D; Gray, III, George T; Luo, Sheng-Nian

    2009-03-01

    This report describes the details of a series of plate impact experiments that were conducted on a gas gun in an effort to validate a new technique for plate impact using the TRIDENT laser to launch thin flyers. The diagnostics fielded were VISAR and identical samples and impactors were used on both platforms. All experimenters agree that the VISAR results should have agreed between the two experimental platforms. The VISAR results did not agree across the platforms and experimenters offer explanations and implications for this outcome.

  12. New techniques will take the sting out of flue gas

    SciTech Connect

    Not Available

    1980-10-08

    A discussion covers some new techniques for reducing NO/sub x/ and/or sulfur dioxide emissions from stack gases, including the installation by Champlin Petroleum Co. of Exxon Research and Engineering Co.'s catalyst-free DeNox system, which relies on ammonia addition, at its Wilmington, California, refinery; UOP Inc.'s demonstration of the Shell Flue Gas Desulfurization (and NO/sub x/ removal) process at a Tampa, Florida, coal-fired unit owned by Tampa Electric Co.; and Sumitomo Chemical Co. Ltd.'s and Mitsui and Co. Ltd.'s plans to use Bergbau-Forschung G.m.b.H. technology, which removes both NO/sub x/ and sulfur dioxide.

  13. Perineal Distensibility Using Epi-no in Twin Pregnancies: Comparative Study with Singleton Pregnancies

    PubMed Central

    Kubotani, Juliana Sayuri; Moron, Antonio Fernandes; Zanetti, Miriam Raquel Diniz; Soares, Vanessa Cardoso Marques; Elito Júnior, Julio

    2014-01-01

    The aims of this study were to compare perineal distensibility between women with twin and singleton pregnancies and to correlate these women's perineal distensibility with anthropometric data. This prospective cross-sectional case-control study was conducted among nulliparous women, of whom 20 were pregnant with twins and 23 with a single fetus. Perineal distensibility was evaluated in the third trimester by means of Epi-no, which was introduced into the vagina and inflated up to the maximum tolerable limit. It was then withdrawn while inflated and its circumference was measured. The unpaired Student's t-test was used to compare perineal distensibility in the two groups and Pearson's correlation coefficient (r) was used to correlate the pregnant women's perineal distensibility with their anthropometric data. There was no difference in perineal distensibility between the twin group (16.51 ± 2.05 cm) and singleton group (16.13 ± 1.67 cm) (P = 0.50). There was a positive correlation between perineal distensibility and abdominal circumference (r = 0.36; P = 0.01). The greater the abdominal circumference was, the greater the perineal distensibility was, regardless of whether the pregnancy was twin or singleton. PMID:25006476

  14. Magnetic sensor for arterial distension and blood pressure monitoring.

    PubMed

    Ruhhammer, Johannes; Herbstritt, Tamara; Ruh, Dominic; Foerster, Katharina; Heilmann, Claudia; Beyersdorf, Friedhelm; Goldschmidtboeing, Frank; Seifert, Andreas; Woias, Peter

    2014-12-01

    A novel sensor for measuring arterial distension, pulse and pressure waveform is developed and evaluated. The system consists of a magnetic sensor which is applied and fixed to arterial vessels without any blood vessel constriction, hence avoiding stenosis. The measurement principle could be validated by in vitro experiments on silicone tubes, and by in vivo experiments in an animal model, thereby indicating the non-linear viscoelastic characteristics of real blood vessels. The sensor is capable to provide absolute measurements of the dynamically varying arterial diameter. By calibrating the sensor, a long-term monitoring system for continuously measuring blood pressure and other cardiovascular parameters could be developed based on the method described. This will improve diagnostics for high risk patients and enable a better, specific treatment.

  15. Hot gas stream application in micro-bonding technique

    NASA Astrophysics Data System (ADS)

    Andrijasevic, Daniela; Giouroudi, Ioanna; Smetana, Walter; Boehm, Stefan; Brenner, Werner

    2006-01-01

    This paper presents a new concept for bonding micro-parts with dimensions in the range of 50 μm to 300 μm. Two different kinds of adhesives - polyurethane adhesive foil and hot melt glue - were applied to a basic substrate by different techniques. The focused and concentrated hot gas stream softened glue which had been applied in a solid state. Micro-parts were then embossed in the softened glue, or covered and shielded by it. In this way, a rigid and compact bond was obtained after cooling. For the positioning of micro-parts (optical fibers), it has been necessary to manufacture adequate V-grooves. Finite element analyses using the ANSYS TM program package were performed in order to evaluate parameters which govern the heat transfer to the adhesive and substrate respectively. Experimental results are in good agreement with results obtained by the numerical simulations. The advantages of this new approach are small system size, low capital costs, simple usage, applicability to many material combinations, easy integration into existing production lines, etc.

  16. New fracturing techniques reduce tight gas sand completion problems

    SciTech Connect

    Bruce, P.L.; Hunter, J.L. ); Kuhlman, R.D. ); Weinheimer, D.D. )

    1992-10-12

    This paper reports on new fracturing stimulation technology which contributed to solving problems in completing tight gas sands in the Carthage Cotton Valley field in Texas. These technologies included improved fluid systems, computer-controlled proppant placement, multiple isotope radioactive logs, mechanical properties logs, and innovative casing design. Drilling activity in the Carthage field commenced on a large scale in 1978 and 1979. At that time, the Natural Gas Policy Act of 1978 (NGPA) first allowed higher gas prices. In 1980, low-permeability sandstones officially were classified as tight gas sands by the Federal Energy Regulatory Commission (FERC). This classification qualified the sands for NGPA incentive gas prices. After the Texas Railroad Commission (RRC) changed the field rules to 320 acre spacing, another round of development drilling began. In 1981 and 1982, Pennzoil drilled and completed 22 infill development wells before the gas market crashed in 1982.

  17. Low Cost Gas Turbine Off-Design Prediction Technique

    NASA Astrophysics Data System (ADS)

    Martinjako, Jeremy

    This thesis seeks to further explore off-design point operation of gas turbines and to examine the capabilities of GasTurb 12 as a tool for off-design analysis. It is a continuation of previous thesis work which initially explored the capabilities of GasTurb 12. The research is conducted in order to: 1) validate GasTurb 12 and, 2) predict off-design performance of the Garrett GTCP85-98D located at the Arizona State University Tempe campus. GasTurb 12 is validated as an off-design point tool by using the program to predict performance of an LM2500+ marine gas turbine. Haglind and Elmegaard (2009) published a paper detailing a second off-design point method and it includes the manufacturer's off-design point data for the LM2500+. GasTurb 12 is used to predict off-design point performance of the LM2500+ and compared to the manufacturer's data. The GasTurb 12 predictions show good correlation. Garrett has published specification data for the GTCP85-98D. This specification data is analyzed to determine the design point and to comment on off-design trends. Arizona State University GTCP85-98D off-design experimental data is evaluated. Trends presented in the data are commented on and explained. The trends match the expected behavior demonstrated in the specification data for the same gas turbine system. It was originally intended that a model of the GTCP85-98D be constructed in GasTurb 12 and used to predict off-design performance. The prediction would be compared to collected experimental data. This is not possible because the free version of GasTurb 12 used in this research does not have a module to model a single spool turboshaft. This module needs to be purchased for this analysis.

  18. Understanding soil-gas velocity leads to new sampling techniques

    SciTech Connect

    Roy, K.A.

    1989-12-01

    Predicting when periods of maximum vertical gas velocity occur for any geographic point mightily increases the sensitivity and reliability of detection. This article discusses sampling programs. Sampling programs can be completed during periods of maximum velocity, allowing field workers to collect the maximum amount of contaminant in trace-gas form per given unit of time.

  19. GRI-sponsored research tests gas measurement techniques

    SciTech Connect

    Kothari, K.M.; Gregor, J.G. )

    1991-09-01

    This paper reports on the Gas Research Institute (GRI) which is managing a comprehensive research and development (R and D) program in gas flow measurement to improve gas metering accuracy and to reduce operation and maintenance costs. A portion of the program is centered on construction of a Metering Research Facility (MRF) and collecting experimental data over a range of Reynolds numbers to determine the effects of upstream flow conditions on orifice and turbine meters. In addition, GRI is sponsoring the development of new concepts for energy content and energy rate measurement: a low-cost, low-power electronic flow measurement device and accurate gas mixtures for use with gas chromatographs and calorimeters.

  20. A Safe and Efficient Technique for the Production of HCl/DCl Gas

    ERIC Educational Resources Information Center

    Mayer, Steven G.; Bard, Raymond R.; Cantrell, Kevin

    2008-01-01

    We present a safe and efficient technique to generate HCl/DCl gas for use in the classic physical chemistry experiment that introduces students to ro-vibrational spectroscopy. The reaction involves thionyl chloride and a mixture of water and deuterium oxide to produce HCl/DCl gas with SO[subscript 2] gas as a byproduct. The entire reaction is…

  1. Evaluation of regional aortic distensibility using color kinesis.

    PubMed

    Kato, Yoshimasa; Kotoh, Keiju; Yamashita, Akio; Furuta, Hidetoshi; Shimazu, Chikasi; Misaki, Takurou

    2003-01-01

    Regional aortic stiffness cannot be evaluated by conventional methods. Regional aortic wall velocity during systole in the descending aorta was evaluated by using transesophageal echocardiography with color kinesis. The authors defined regional aortic distensibility (RAD) by considering pulse pressure, with RAD (microm/s/mm Hg) = (regional aortic wall velocity)/(pulse pressure). RAD was evaluated in 38 patients who had coronary artery disease (CAD) and 10 who did not. RAD decreased depending on aging (partial regression coefficient was -5.39 x 10(-1), p<0.001), and RAD was lower in the CAD group than that in the no-CAD group (p<0.05). In the CAD group, 19 patients had a single fixed plaque (4 calcified and 15 noncalcified plaques). RAD in the calcified plaque was lower than that in the noncalcified plaque (p<0.01), and RAD was lower in the noncalcified plaque than that in the no-plaque region (p<0.05). In noncalcified plaques, the relation between RAD and maximum intimal thickness had a significant correlation, r=0.7, p<0.001. The residual of RAD from the regression line was significantly larger in the calcified plaque than that in the noncalcified plaque (p<0.001). In conclusion, RAD can express increasing regional aortic wall stiffness brought about by arteriosclerosis quantitatively. Color kinesis provides information on characteristic difference between calcified and noncalcified plaque.

  2. Advancement and application of gas chromatography isotope ratio mass spectrometry techniques for atmospheric trace gas analysis

    NASA Astrophysics Data System (ADS)

    Giebel, Brian M.

    2011-12-01

    The use of gas chromatography isotope ratio mass spectrometry (GC-IRMS) for compound specific stable isotope analysis is an underutilized technique because of the complexity of the instrumentation and high analytical costs. However stable isotopic data, when coupled with concentration measurements, can provide additional information on a compounds production, transformation, loss, and cycling within the biosphere and atmosphere. A GC-IRMS system was developed to accurately and precisely measure delta13C values for numerous oxygenated volatile organic compounds having natural and anthropogenic sources. The OVOCs include methanol, ethanol, acetone, methyl ethyl ketone, 2-pentanone, and 3-pentanone. Guided by the requirements for analysis of trace components in air, the GC-IRMS system was developed with the goals of increasing sensitivity, reducing dead-volume and peak band broadening, optimizing combustion and water removal, and decreasing the split ratio to the IRMS. The technique relied on a two-stage preconcentration system, a low-volume capillary reactor and water trap, and a balanced reference gas delivery system. Measurements were performed on samples collected from two distinct sources (i.e. biogenic and vehicle emissions) and ambient air collected from downtown Miami and Everglades National Park. However, the instrumentation and the method have the capability to analyze a variety of source and ambient samples. The measured isotopic signatures that were obtained from source and ambient samples provide a new isotopic constraint for atmospheric chemists and can serve as a new way to evaluate their models and budgets for many OVOCs. In almost all cases, OVOCs emitted from fuel combustion were enriched in 13C when compared to the natural emissions of plants. This was particularly true for ethanol gas emitted in vehicle exhaust, which was observed to have a uniquely enriched isotopic signature that was attributed to ethanol's corn origin and use as an alternative

  3. Risk management technique for liquefied natural gas facilities

    NASA Technical Reports Server (NTRS)

    Fedor, O. H.; Parsons, W. N.

    1975-01-01

    Checklists have been compiled for planning, design, construction, startup and debugging, and operation of liquefied natural gas facilities. Lists include references to pertinent safety regulations. Methods described are applicable to handling of other hazardous materials.

  4. Pressure distension in leg vessels as influenced by prolonged bed rest and a pressure habituation regimen.

    PubMed

    Eiken, Ola; Mekjavic, Igor B; Kounalakis, Stylianos N; Kölegård, Roger

    2016-06-15

    Bed rest increases pressure distension in arteries, arterioles, and veins of the leg. We hypothesized that bed-rest-induced deconditioning of leg vessels is governed by the removal of the local increments in transmural pressure induced by assuming erect posture and, therefore, can be counteracted by intermittently increasing local transmural pressure during the bed rest. Ten men underwent 5 wk of horizontal bed rest. A subatmospheric pressure (-90 mmHg) was intermittently applied to one lower leg [pressure habituation (PH) leg]. Vascular pressure distension was investigated before and after the bed rest, both in the PH and control (CN) leg by increasing local distending pressure, stepwise up to +200 mmHg. Vessel diameter and blood flow were measured in the posterior tibial artery and vessel diameter in the posterior tibial vein. In the CN leg, bed rest led to 5-fold and 2.7-fold increments (P < 0.01) in tibial artery pressure-distension and flow responses, respectively, and to a 2-fold increase in tibial vein pressure distension. In the PH leg, arterial pressure-distension and flow responses were unaffected by bed rest, whereas bed rest led to a 1.5-fold increase in venous pressure distension. It thus appears that bed-rest-induced deconditioning of leg arteries, arterioles, and veins is caused by removal of gravity-dependent local pressure loads and may be abolished or alleviated by a local pressure-habituation regimen. PMID:27079693

  5. Pressure distension in leg vessels as influenced by prolonged bed rest and a pressure habituation regimen.

    PubMed

    Eiken, Ola; Mekjavic, Igor B; Kounalakis, Stylianos N; Kölegård, Roger

    2016-06-15

    Bed rest increases pressure distension in arteries, arterioles, and veins of the leg. We hypothesized that bed-rest-induced deconditioning of leg vessels is governed by the removal of the local increments in transmural pressure induced by assuming erect posture and, therefore, can be counteracted by intermittently increasing local transmural pressure during the bed rest. Ten men underwent 5 wk of horizontal bed rest. A subatmospheric pressure (-90 mmHg) was intermittently applied to one lower leg [pressure habituation (PH) leg]. Vascular pressure distension was investigated before and after the bed rest, both in the PH and control (CN) leg by increasing local distending pressure, stepwise up to +200 mmHg. Vessel diameter and blood flow were measured in the posterior tibial artery and vessel diameter in the posterior tibial vein. In the CN leg, bed rest led to 5-fold and 2.7-fold increments (P < 0.01) in tibial artery pressure-distension and flow responses, respectively, and to a 2-fold increase in tibial vein pressure distension. In the PH leg, arterial pressure-distension and flow responses were unaffected by bed rest, whereas bed rest led to a 1.5-fold increase in venous pressure distension. It thus appears that bed-rest-induced deconditioning of leg arteries, arterioles, and veins is caused by removal of gravity-dependent local pressure loads and may be abolished or alleviated by a local pressure-habituation regimen.

  6. Effects of octreotide on responses to colorectal distension in the rat

    PubMed Central

    Su, X; Burton, M; Gebhart, G

    2001-01-01

    BACKGROUND AND AIMS—It has been suggested that the analgesic effect of the somatostatin analogue octreotide in visceral pain involves peripheral mechanisms. We evaluated the effect of octreotide on responses to noxious colorectal distension in rats.
METHODS—In a behavioural study, pressor and electromyographic responses to colorectal distension were evaluated before and after intravenous or intrathecal administration of octreotide. In pelvic nerve afferent fibre recordings, responses of mechanosensitive fibres innervating the colon to noxious colorectal distension (80 mm Hg, 30 seconds) were tested before and after octreotide.
RESULTS—Octreotide was ineffective in attenuating responses to colorectal distension in either normal or acetic acid inflamed colon when administered intravenously but attenuated responses when given intrathecally. Administration of octreotide over a broad dose range (0.5 µg/kg to 2.4 mg/kg) did not alter responses of afferent fibres to noxious colorectal distension in untreated, or acetic acid or zymosan treated colons.
CONCLUSIONS—In the rat, octreotide has no peripheral (pelvic nerve) modulatory action in visceral nociception. The antinociceptive effect of octreotide in this model of visceral nociception is mediated by an action at central sites.


Keywords: octreotide; colorectal distension; electromyographic responses; afferent fibres; visceral pain; analgesic effect; rat PMID:11302968

  7. The influence of intraluminal thrombus on noninvasive abdominal aortic aneurysm wall distensibility measurement.

    PubMed

    Metaxa, Eleni; Kontopodis, Nikolaos; Vavourakis, Vasileios; Tzirakis, Konstantinos; Ioannou, Christos V; Papaharilaou, Yannis

    2015-04-01

    Abdominal aortic aneurysm wall distensibility can be estimated by measuring pulse pressure and the corresponding sac volume change, which can be obtained by measuring wall displacement. This approach, however, may introduce error if the role of thrombus in assisting the wall in bearing the pulse pressure loading is neglected. Our aim was to introduce a methodology for evaluating and potentially correcting this error in estimating distensibility. Electrocardiogram-gated computed tomography images of eleven patients were obtained, and the volume change between diastole and systole was measured. Using finite element procedures, we determined the equivalent pulse pressure loading that should be applied to the wall of a model where thrombus was digitally removed, to yield the same sac volumetric increase caused by applying the luminal pulse pressure to the model with thrombus. The equivalent instead of the measured pulse pressure was used in the distensibility expression. For a relative volumetric thrombus deposition (V ILT) of 50 %, a 62 % distensibility underestimation resulted when thrombus role was neglected. A strong linear correlation was observed between distensibility underestimation and V ILT. To assess the potential value of noninvasive wall distensibility measurement in rupture risk stratification, the role of thrombus on wall loading should be further investigated. PMID:25548097

  8. Comparing and assessing different measurement techniques for mercury in coal systhesis gas

    SciTech Connect

    Maxwell, D.P.; Richardson, C.F.

    1995-11-01

    Three mercury measurement techniques were performed on synthesis gas streams before and after an amine-based sulfur removal system. The syngas was sampled using (1) gas impingers containing a nitric acid-hydrogen peroxide solution, (2) coconut-based charcoal sorbent, and (3) an on-line atomic absorption spectrophotometer equipped with a gold amalgamation trap and cold vapor cell. Various impinger solutions were applied upstream of the gold amalgamation trap to remove hydrogen sulfide and isolate oxidized and elemental species of mercury. The results from these three techniques are compared to provide an assessment of these measurement techniques in reducing gas atmospheres.

  9. Peripheral venous distension elicits a blood pressure raising reflex in young and middle-aged adults.

    PubMed

    Matthews, Evan L; Brian, Michael S; Coyle, Dana E; Edwards, David G; Stocker, Sean D; Wenner, Megan M; Farquhar, William B

    2016-06-01

    Distension of peripheral veins in humans elicits a pressor and sympathoexcitatory response that is mediated through group III/IV skeletal muscle afferents. There is some evidence that autonomic reflexes mediated by these sensory fibers are blunted with increasing age, yet to date the venous distension reflex has only been studied in young adults. Therefore, we tested the hypothesis that the venous distension reflex would be attenuated in middle-aged compared with young adults. Nineteen young (14 men/5 women, 25 ± 1 yr) and 13 middle-aged (9 men/4 women, 50 ± 2 yr) healthy normotensive participants underwent venous distension via saline infusion through a retrograde intravenous catheter in an antecubital vein during limb occlusion. Beat-by-beat blood pressure, muscle sympathetic nerve activity (MSNA), and model flow-derived cardiac output (Q), and total peripheral resistance (TPR) were recorded throughout the trial. Mean arterial pressure (MAP) increased during the venous distension in both young (baseline 83 ± 2, peak 94 ± 3 mmHg; P < 0.05) and middle-aged adults (baseline 88 ± 2, peak 103 ± 3 mmHg; P < 0.05). MSNA also increased in both groups [young: baseline 886 ± 143, peak 1,961 ± 242 arbitrary units (AU)/min; middle-aged: baseline 1,164 ± 225, peak 2,515 ± 404 AU/min; both P < 0.05]. TPR (P < 0.001), but not Q (P = 0.76), increased during the trial. However, the observed increases in blood pressure, MSNA, and TPR were similar between young and middle-aged adults. Additionally, no correlation was found between age and the response to venous distension (all P > 0.05). These findings suggest that peripheral venous distension elicits a pressor and sympathetic response in middle-aged adults similar to the response observed in young adults. PMID:27053648

  10. GABAA receptors expression pattern in rat brain following low pressure distension of the stomach.

    PubMed

    Sabbatini, M; Molinari, C; Grossini, E; Piffanelli, V; Mary, D A S G; Vacca, G; Cannas, M

    2008-03-18

    It is known that gastric mechanoreceptor stimuli are widely integrated into neuronal circuits that involve visceral nuclei of hindbrain as well as several central brain areas. GABAergic neurons are widely represented in hindbrain nuclei controlling gastric motor functions, but limited information is available specifically about GABA(A)-responding neurons in brain visceral areas. The present investigation was designed to determine the central sensory neuronal pathways and their GABA(A)-alpha1 and -alpha3 receptor presenting neurons that respond to gastric mechanoreceptor stimulation within the entire rat brain. Low pressure gastric distension was used to deliver physiological mechanical stimuli in anesthetized rats, and different protocols of gastric distension were performed to mimic different stimulation patterns with and without sectioning vagal and/or splanchnic afferent nerves. Mapping of activated neurons was investigated using double colorimetric immunohistochemistry for GABA(A)-alpha1 or -alpha3 subunits and c-Fos. Following stomach distension, neurons expressing GABA(A) receptors with alpha1 or alpha3 subunits were detected. Low frequency gastric distension induced c-Fos expression in nucleus tractus solitarii (NTS) only, whereas in the high frequency gastric distension c-Fos positive nuclei were found in lateral reticular nucleus and in NTS in addition to some forebrain areas. In contrast, during the tonic-rapid gastric distension the neuronal activation was found in hindbrain, midbrain and forebrain areas. Moreover different protocols of gastric stimulation activated diverse patterns of neurons presenting GABA(A)-alpha1 or -alpha3 receptors within responding brain nuclei, which may indicate a probable functional significance of differential expression of GABA(A)-responding neurons. The same protocol of gastric distension performed in vagotomized rats has confirmed the primary role of the vagus in the response of activation of gastric brain areas, whereas

  11. Solvent-free microextraction techniques in gas chromatography.

    PubMed

    Laaks, Jens; Jochmann, Maik A; Schmidt, Torsten C

    2012-01-01

    Microextraction techniques represent a major part of modern sample preparation in the analysis of organic micropollutants. This article provides a short overview of recent developments in solvent-free microextraction techniques. From the first open-tubular trap techniques in the mid-1980s to recent packed-needle devices, different implementations of in-needle packings for microextraction are discussed with their characteristic benefits, shortcomings and possible sampling modes. Special emphasis is placed on methods providing full automation and solvent exclusion. In this context, in-tube extraction and the needle trap are discussed, with an overview of current research on new sorbent materials, together with the requirements for more efficient method development. PMID:22057686

  12. Sensor Data Qualification Technique Applied to Gas Turbine Engines

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey T.; Simon, Donald L.

    2013-01-01

    This paper applies a previously developed sensor data qualification technique to a commercial aircraft engine simulation known as the Commercial Modular Aero-Propulsion System Simulation 40,000 (C-MAPSS40k). The sensor data qualification technique is designed to detect, isolate, and accommodate faulty sensor measurements. It features sensor networks, which group various sensors together and relies on an empirically derived analytical model to relate the sensor measurements. Relationships between all member sensors of the network are analyzed to detect and isolate any faulty sensor within the network.

  13. Optimal sensor locations for the backward Lagrangian stochastic technique in measuring lagoon gas emission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the impact of gas concentration and wind sensor locations on the accuracy of the backward Lagrangian stochastic inverse-dispersion technique (bLS) for measuring gas emission rates from a typical lagoon environment. Path-integrated concentrations (PICs) and 3-dimensional (3D) wi...

  14. Offshore Adriatic marginal gas fields: An approach to the technique of reservoir development

    SciTech Connect

    Montanari, A.; Bolelli, V.; Piccoli, G.

    1986-01-01

    The application of accelerated gas blowdown and wire line techniques in reservoir development and exploitation is presented for an off-shore Adriatic marginal gas field. The approach discussed in this paper utilizes selective completion, very low reserves/production ratio, sequential production, Through Tubing Bridge Plug and Through Tubing Perforation techniques to avoid the use of costly workover rigs and to allow economically convenient exploitation of a structure which otherwise would have been abandoned.

  15. The clinical effect of hydraulic distension plus manual therapy on patients with frozen shoulder.

    PubMed

    Kwak, Kwang-Il; Kim, Eun-Kyung

    2016-08-01

    [Purpose] This study aimed to develop a clinical protocol for the treatment of frozen shoulder using applied hydraulic distension plus manual therapy. [Subjects and Methods] Patients were randomly assigned to 2 groups: 60 patients in group A were treated with hydraulic distension plus manual therapy, and 61 in group B were treated with hydraulic distension alone. Treatment effects were assessed using the Visual Analog Scale (VAS) (pain and satisfaction), and active range of motion of the shoulder (forward flexion, internal and external rotation) before treatments and at 2, 6, 12, 24 weeks, and 1 year after the last injections. [Results] Patients in group A achieved faster pain relief and better satisfaction than patients in group B during the 6 weeks after treatment. However, no significant difference in VAS was observed between the groups at final follow-up. AROM of the shoulder was improved at final follow-up in both groups. [Conclusion] Hydraulic distension plus manual therapy provided faster pain relief, a higher level of patient satisfaction, and an earlier improvement in AROM of the shoulder than hydraulic distension alone in patients with frozen shoulder. PMID:27630441

  16. Rectal reservoir and sensory function studied by graded isobaric distension in normal man.

    PubMed Central

    Akervall, S; Fasth, S; Nordgren, S; Oresland, T; Hultén, L

    1989-01-01

    The rectal expansion and concomitant sensory function on graded, isobaric, rectal distension within the interval 5-60 cm H2O was investigated in 36 healthy young volunteers. Anal pressure and electromyography (EMG) from the external anal sphincter were simultaneously recorded. Rectal distension caused an initial rapid expansion followed by transient, often repeated, reflex rectal contractions and a slow gradual increase of rectal volume. The maximal volume displaced by the first reflex rectal contraction was 18 (13) ml, which was less than 10% of the volume at 60 s. The pressure threshold for appreciation of rectal filling was 12 cm H2O (95% CL 5-15 cm H2O) and coincided with the threshold for rectoanal inhibition. Urge to defecate was experienced at 28 cm H2O (15-50 cm H2O) distension pressure, which was close to the threshold for maximal rectal contraction, also coinciding with the appearance of the external anal sphincter reflex. The interindividual variation of rectal volume on distension with defined pressures varied widely, indicating a considerable variation of rectal compliance in normal man. No correlation was found between rectal volume and sex or anthropometric variables. The relative variations in pressure thresholds for eliciting rectal sensation and rectoanal reflexes were less than the corresponding threshold volumes. It was concluded that the dynamic rectal response to distension reflects a well graded reflex adjustment ideal for a reservoir. PMID:2714682

  17. The clinical effect of hydraulic distension plus manual therapy on patients with frozen shoulder

    PubMed Central

    Kwak, Kwang-Il; Kim, Eun-Kyung

    2016-01-01

    [Purpose] This study aimed to develop a clinical protocol for the treatment of frozen shoulder using applied hydraulic distension plus manual therapy. [Subjects and Methods] Patients were randomly assigned to 2 groups: 60 patients in group A were treated with hydraulic distension plus manual therapy, and 61 in group B were treated with hydraulic distension alone. Treatment effects were assessed using the Visual Analog Scale (VAS) (pain and satisfaction), and active range of motion of the shoulder (forward flexion, internal and external rotation) before treatments and at 2, 6, 12, 24 weeks, and 1 year after the last injections. [Results] Patients in group A achieved faster pain relief and better satisfaction than patients in group B during the 6 weeks after treatment. However, no significant difference in VAS was observed between the groups at final follow-up. AROM of the shoulder was improved at final follow-up in both groups. [Conclusion] Hydraulic distension plus manual therapy provided faster pain relief, a higher level of patient satisfaction, and an earlier improvement in AROM of the shoulder than hydraulic distension alone in patients with frozen shoulder. PMID:27630441

  18. Local and remote lesions in horses subjected to small colon distension and decompression

    PubMed Central

    Faleiros, Rafael R.; Macoris, Delphim G.; Alves, Geraldo Eleno S.; Souza, Danielle G.; Teixeira, Mauro M.; Moore, Rustin M.

    2008-01-01

    The purpose of this study was to observe and characterize colonic and lung lesions in horses subjected to experimental distension and decompression of the small colon. Sixteen healthy adult horses were divided into 2 groups: 9 horses that were subjected to distension of the small colon by means of a latex balloon surgically implanted in the lumen and inflated to a pressure of 40 mm Hg for 4 h, and 7 horses in which the balloon was implanted but not inflated. Colonic biopsy specimens were collected before balloon implantation, at the end of the period of obstruction, and 1.5 and 12 h after decompression and were examined for hemorrhage, edema, and neutrophil infiltration; myeloperoxidase (MPO) activity and hemoglobin concentration were measured as well. At the end of the experiment, lung samples were also collected and examined for neutrophil accumulation and MPO activity. The mucosa was not affected by luminal distension; lesions were restricted to the seromuscular layer. Neutrophil accumulation and edema were observed in the samples from both groups of horses but were greater in those from the distension group, in which there was also hemorrhage, fibrin deposition, and increased MPO activity in the seromuscular layer. Similarly, there was greater accumulation of neutrophils in the lung samples from the distension group than in those from the sham-operated group, as determined by histologic evaluation and MPO assay. These findings provide new evidence of reperfusion injury and a systemic inflammatory response, followed by remote lesions, in horses with intestinal obstruction. PMID:18214165

  19. The clinical effect of hydraulic distension plus manual therapy on patients with frozen shoulder.

    PubMed

    Kwak, Kwang-Il; Kim, Eun-Kyung

    2016-08-01

    [Purpose] This study aimed to develop a clinical protocol for the treatment of frozen shoulder using applied hydraulic distension plus manual therapy. [Subjects and Methods] Patients were randomly assigned to 2 groups: 60 patients in group A were treated with hydraulic distension plus manual therapy, and 61 in group B were treated with hydraulic distension alone. Treatment effects were assessed using the Visual Analog Scale (VAS) (pain and satisfaction), and active range of motion of the shoulder (forward flexion, internal and external rotation) before treatments and at 2, 6, 12, 24 weeks, and 1 year after the last injections. [Results] Patients in group A achieved faster pain relief and better satisfaction than patients in group B during the 6 weeks after treatment. However, no significant difference in VAS was observed between the groups at final follow-up. AROM of the shoulder was improved at final follow-up in both groups. [Conclusion] Hydraulic distension plus manual therapy provided faster pain relief, a higher level of patient satisfaction, and an earlier improvement in AROM of the shoulder than hydraulic distension alone in patients with frozen shoulder.

  20. The clinical effect of hydraulic distension plus manual therapy on patients with frozen shoulder

    PubMed Central

    Kwak, Kwang-Il; Kim, Eun-Kyung

    2016-01-01

    [Purpose] This study aimed to develop a clinical protocol for the treatment of frozen shoulder using applied hydraulic distension plus manual therapy. [Subjects and Methods] Patients were randomly assigned to 2 groups: 60 patients in group A were treated with hydraulic distension plus manual therapy, and 61 in group B were treated with hydraulic distension alone. Treatment effects were assessed using the Visual Analog Scale (VAS) (pain and satisfaction), and active range of motion of the shoulder (forward flexion, internal and external rotation) before treatments and at 2, 6, 12, 24 weeks, and 1 year after the last injections. [Results] Patients in group A achieved faster pain relief and better satisfaction than patients in group B during the 6 weeks after treatment. However, no significant difference in VAS was observed between the groups at final follow-up. AROM of the shoulder was improved at final follow-up in both groups. [Conclusion] Hydraulic distension plus manual therapy provided faster pain relief, a higher level of patient satisfaction, and an earlier improvement in AROM of the shoulder than hydraulic distension alone in patients with frozen shoulder.

  1. Oral contrast agents for small bowel MRI: comparison of different additives to optimize bowel distension.

    PubMed

    Ajaj, Waleed; Goehde, Susanne C; Schneemann, Hubert; Ruehm, Stefan G; Debatin, Jörg F; Lauenstein, Thomas C

    2004-03-01

    The purpose of this study was to compare two osmotic carbohydrate sugar alcohols (mannitol 2.5% and sorbitol 2.5%, 2.0%, and 1.5% watery solutions) in combination with 0.2% locust bean gum (LBG) for small bowel distension for MR imaging. Small bowel distension was quantified on coronal 2D TrueFISP images by measuring the diameters of 16 small bowel loops in each of 12 healthy subjects (age range 31-55 years). Additionally, the grade of small bowel distension was rated qualitatively. Patient acceptance concerning nausea, vomiting, flatulence, and diarrhea was noted for each solution, and all results were compared by a Wilcoxon test or t test, respectively. The ingestion of water combined with LBG and either 2.5% mannitol or 2.0% sorbitol showed the best distension of the small bowel. The lowest side effect rate was observed following ingestion of sorbitol in a concentration of 2.0 and 1.5%. Based on these data, we recommend a combination of LBG and 2% sorbitol use for optimal bowel distension and minimal side effects resulting in enhanced patient acceptance. PMID:14634782

  2. Validity of using backward Lagrangian Stochastic technique in measuring trace gas emission from treatment lagoon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluates the accuracy of measuring trace gas emission from treatment lagoons using backward Lagrangian stochastic (bLs) technique. The bLs technique was originally developed for relatively homogeneous terrains without any obstacles causing significant windflow disturbance. The errors ass...

  3. Association of parity with carotid diameter and distensibility: multi-ethnic study of atherosclerosis.

    PubMed

    Vaidya, Dhananjay; Bennett, Wendy L; Sibley, Christopher T; Polak, Joseph F; Herrington, David M; Ouyang, Pamela

    2014-08-01

    Pregnancy and childbirth are associated with hemodynamic changes and vascular remodeling. It is not known whether parity is associated with later adverse vascular properties such as larger arterial diameter, wall thickness, and lower distensibility. We used baseline data from 3283 women free of cardiovascular disease aged 45 to 84 years enrolled in the population-based Multi-Ethnic Study of Atherosclerosis. Participants self-reported parity status. Ultrasound-derived carotid artery lumen diameters and brachial artery blood pressures were measured at peak-systole and end-diastole. Common carotid intima-media thickness was also measured. Regression models to determine the association of carotid distensibility coefficient, lumen diameter, and carotid intima-media thickness with parity were adjusted for age, race, height, weight, diabetes mellitus, current smoking, blood pressure medication use, and total and high-density lipoprotein cholesterol levels. The prevalence of nulliparity was 18%. In adjusted models, carotid distensibility coefficient was 0.09×10−5 Pa−1 lower (P=0.009) in parous versus nulliparous women. Among parous women, there was a nonlinear association with the greatest carotid distensibility coefficient seen in women with 2 live births and significantly lower distensibility seen in primiparas (P=0.04) or with higher parity >2 (P=0.005). No such pattern of association with parity was found for lumen diameter or carotid intima-media thickness. Parity is associated with lower carotid artery distensibility, suggesting arterial remodeling that lasts beyond childbirth. These long-term effects on the vasculature may explain the association of parity with cardiovascular events later in life.

  4. Influence of trimebutine on inflammation- and stress-induced hyperalgesia to rectal distension in rats.

    PubMed

    Lacheze, C; Coelho, A M; Fioramonti, J; Buéno, L

    1998-08-01

    The effects of trimebutine and its major metabolite, N-desmethyltrimebutine on inflammation- and stress-induced rectal hyperalgesia have been evaluated in rats fitted with electrodes implanted in the longitudinal striated muscle of the abdomen. Intermittent rectal distension was performed before and 3 days after induction of rectal inflammation by local infusion of trinitrobenzenesulphonic acid (in ethanol). Stress consisted of 2h partial restraint and rectal distension was performed before and 30min after the end of the partial restraint session. The animals were treated intraperitoneally with trimebutine or desmethyltrimebutine (5, 10 or 20mgkg(-1)) or vehicle 15min before rectal distension. Naloxone (1mgkg(-1)) or saline was injected subcutaneously before trimebutine and desmethyltrimebutine. Before treatment trimebutine at the highest dose (20mgkg(-1)) reduced the abdominal response to rectal distension for the highest volume of distension (1.6mL) whereas desmethyltrimebutine was inactive. After rectocolitis the abdominal response to rectal distension was enhanced and trimebutine at 5mgkg(-1) reduced and at 10 mgkg(-1) suppressed inflammation-induced hyperalgesia, an effect reversed by naloxone. Desmethyltrimebutine was inactive. Stress-induced hypersensitivity was attenuated or suppressed, or both, by trimebutine and desmethyltrimebutine at doses of 5, 10 or 20mgkg(-l); greater efficacy was observed for desmethyltrimebutine and the effects were not reversed by naloxone. It was concluded that trimebutine and desmethyltrimebutine are active against inflammation- and stress-induced rectal hyperalgesia but act differently. The effect of trimebutine on inflammation-induced hyperalgesia is mediated through opioid receptors. PMID:9751458

  5. Nongray gas analyses for reflecting walls utilizing a flux technique

    NASA Technical Reports Server (NTRS)

    Menart, J. A.; Lee, Haeok S.

    1993-01-01

    A flux formulation for a planar slab of molecular gas radiation bounded by diffuse reflecting walls is developed. While this formulation is limited to the planar geometry, it is useful for studying approximations necessary in modeling nongray radiative heat transfer. The governing equations are derived by considering the history of multiple reflections between the walls. Accurate solutions are obtained by explicitly accounting for a finite number of reflections and approximating the spectral effects of the remaining reflections. Four approximate methods are presented and compared using a single absorption band of H2O. All four methods reduce to an identical zeroth-order formulation, which accounts for all reflections approximately but does handle nonreflected radiation correctly. A single absorption band of CO2 is also considered using the best-behaved approximation for higher orders. A zeroth-order formulation is sufficient to predict the radiative transfer accurately for many cases considered. For highly reflecting walls, higher order solutions are necessary for better accuracy. Including all the important bands of H2O, the radiative source distributions are also obtained for two different temperature and concentration profiles.

  6. Application of conventional oil and gas drilling techniques to the production of gas from garbage

    SciTech Connect

    Giuliani, A.J.

    1980-01-01

    Although not a complete answer to the US's current energy problems, methane from sanitary landfills is one of the most economical substitute gas supplies. The methane-recovery state-of-the-art as applied at landfills now operating in California and New York and the construction of landfill wells and the various gas-extraction methods are discussed. Because landfill characteristics differ, the success of a methane-recovery operation depends on careful research, study, and initial testing of the specific site; additionally, cooperation is necessary at both government and industry levels. The most reliable route to utilization is to upgrade the landfill gas for blending with natural gas in a local distribution system or transmission line.

  7. Renal clearance studies of effect of left atrial distension in the dog.

    NASA Technical Reports Server (NTRS)

    Kinney, M. J.; Discala, V. A.

    1972-01-01

    Investigation of the water diuresis of left atrial distension in 16 dogs on the basis of clearance studies employing hydration, chronic and acute salt loading, deoxycorticosterone (DOCA) in excess, and distal tubular nephron blockade with diuretics. The diuresis was found in hydrated and salt-loaded dogs and was independent of DOCA and presumed renin depletion. It was not found in five dogs after distal tubular blockade. No significant reproducible saluresis was ever documented. The water diuresis was always stopped by exogenous vasopressin (seven dogs). Antidiuretic hormone inhibition with distal tubular nephron water permeability changes appears to be the sole mechanism of the diuresis of left atrial distension in the dog.

  8. The development of an electrochemical technique for in situ calibrating of combustible gas detectors

    NASA Technical Reports Server (NTRS)

    Shumar, J. W.; Lantz, J. B.; Schubert, F. H.

    1976-01-01

    A program to determine the feasibility of performing in situ calibration of combustible gas detectors was successfully completed. Several possible techniques for performing the in situ calibration were proposed. The approach that showed the most promise involved the use of a miniature water vapor electrolysis cell for the generation of hydrogen within the flame arrestor of a combustible gas detector to be used for the purpose of calibrating the combustible gas detectors. A preliminary breadboard of the in situ calibration hardware was designed, fabricated and assembled. The breadboard equipment consisted of a commercially available combustible gas detector, modified to incorporate a water vapor electrolysis cell, and the instrumentation required for controlling the water vapor electrolysis and controlling and calibrating the combustible gas detector. The results showed that operation of the water vapor electrolysis at a given current density for a specific time period resulted in the attainment of a hydrogen concentration plateau within the flame arrestor of the combustible gas detector.

  9. Effects of gas composition in headspace and bicarbonate concentrations in media on gas and methane production, degradability, and rumen fermentation using in vitro gas production techniques.

    PubMed

    Patra, Amlan Kumar; Yu, Zhongtang

    2013-07-01

    Headspace gas composition and bicarbonate concentrations in media can affect methane production and other characteristics of rumen fermentation in in vitro gas production systems, but these 2 important factors have not been evaluated systematically. In this study, these 2 factors were investigated with respect to gas and methane production, in vitro digestibility of feed substrate, and volatile fatty acid (VFA) profile using in vitro gas production techniques. Three headspace gas compositions (N2+ CO2+ H2 in the ratio of 90:5:5, CO2, and N2) with 2 substrate types (alfalfa hay only, and alfalfa hay and a concentrate mixture in a 50:50 ratio) in a 3×2 factorial design (experiment 1) and 3 headspace compositions (N2, N2 + CO2 in a 50:50 ratio, and CO2) with 3 bicarbonate concentrations (80, 100, and 120 mM) in a 3×3 factorial design (experiment 2) were evaluated. In experiment 1, total gas production (TGP) and net gas production (NGP) was the lowest for CO2, followed by N2, and then the gas mixture. Methane concentration in headspace gas after fermentation was greater for CO2 than for N2 and the gas mixture, whereas total methane production (TMP) and net methane production (NMP) were the greatest for CO2, followed by the gas mixture, and then N2. Headspace composition did not affect in vitro digestibility or the VFA profile, except molar percentages of propionate, which were greater for CO2 and N2 than for the gas mixture. Methane concentration in headspace gas, TGP, and NGP were affected by the interaction of headspace gas composition and substrate type. In experiment 2, increasing concentrations of CO2 in the headspace decreased TGP and NGP quadratically, but increased the concentrations of methane, NMP, and in vitro fiber digestibility linearly, and TMP quadratically. Fiber digestibility, TGP, and NGP increased linearly with increasing bicarbonate concentrations in the medium. Concentrations of methane and NMP were unaffected by bicarbonate concentration, but

  10. Leak testing of bubble-tight dampers using tracer gas techniques

    SciTech Connect

    Lagus, P.L.; DuBois, L.J.; Fleming, K.M.

    1995-02-01

    Recently tracer gas techniques have been applied to the problem of measuring the leakage across an installed bubble-tight damper. A significant advantage of using a tracer gas technique is that quantitative leakage data are obtained under actual operating differential pressure conditions. Another advantage is that leakage data can be obtained using relatively simple test setups that utilize inexpensive materials without the need to tear ducts apart, fabricate expensive blank-off plates, and install test connections. Also, a tracer gas technique can be used to provide an accurate field evaluation of the performance of installed bubble-tight dampers on a periodic basis. Actual leakage flowrates were obtained at Zion Generating Station on four installed bubble-tight dampers using a tracer gas technique. Measured leakage rates ranged from 0.01 CFM to 21 CFM. After adjustment and subsequent retesting, the 21 CFM damper leakage was reduced to a leakage of 3.8 CFM. In light of the current regulatory climate and the interest in Control Room Habitability issues, imprecise estimates of critical air boundary leakage rates--such as through bubble-tight dampers--are not acceptable. These imprecise estimates can skew radioactive dose assessments as well as chemical contaminant exposure calculations. Using a tracer gas technique, the actual leakage rate can be determined. This knowledge eliminates a significant source of uncertainty in both radioactive dose and/or chemical exposure assessments.

  11. Gas to particle conversion-gas exchange technique for direct analysis of metal carbonyl gas by inductively coupled plasma mass spectrometry.

    PubMed

    Nishiguchi, Kohei; Utani, Keisuke; Gunther, Detlef; Ohata, Masaki

    2014-10-21

    A novel gas to particle conversion-gas exchange technique for the direct analysis of metal carbonyl gas by inductively coupled plasma mass spectrometry (ICPMS) was proposed and demonstrated in the present study. The technique is based on a transfer of gas into particle, which can be directly analyzed by ICPMS. Particles from metal carbonyl gases such as Cr(CO)6, Mo(CO)6, and W(CO)6 are formed by reaction with ozone (O3) and ammonium (NH3) gases within a newly developed gas to particle conversion device (GPD). The reaction mechanism of the gas to particle conversion is based on either oxidation of metal carbonyl gas by O3 or agglomeration of metal oxide with ammonium nitrate (NH4NO3) which is generated by the reaction of O3 and NH3. To separate the reaction gases (remaining O3 and NH3) from the formed particles, a previously reported gas exchange device (GED) was used and the in argon stabilized analyte particles were directly introduced and measured by ICPMS. This new technique provided limits of detection (LOD) of 0.15 pL L(-1) (0.32 ng m(-3)), 0.02 pL L(-1) (0.07 ng m(-3)), and 0.01 pL L(-1) (0.07 ng m(-3)) for Cr(CO)6, Mo(CO)6, and W(CO)6, respectively, which were 4-5 orders of magnitude lower than those conventional applied for detecting these gases, e.g., gas chromatography with electron captured detector (GC-ECD) as well as Fourier transform-infrared spectroscopy (FT-IR). The achieved LODs were also similar or slightly better than those for ICPMS coupled to GC. Since the gas to particle conversion technique can achieve the direct measurement of metal carbonyl gases as well as the removal of reaction and ambient gases from metal carbonyl gases, the technique is considered to be well suited to monitor gas quality in semiconductor industry, engine exhaust gases, and or waste incineration products.

  12. Gas to particle conversion-gas exchange technique for direct analysis of metal carbonyl gas by inductively coupled plasma mass spectrometry.

    PubMed

    Nishiguchi, Kohei; Utani, Keisuke; Gunther, Detlef; Ohata, Masaki

    2014-10-21

    A novel gas to particle conversion-gas exchange technique for the direct analysis of metal carbonyl gas by inductively coupled plasma mass spectrometry (ICPMS) was proposed and demonstrated in the present study. The technique is based on a transfer of gas into particle, which can be directly analyzed by ICPMS. Particles from metal carbonyl gases such as Cr(CO)6, Mo(CO)6, and W(CO)6 are formed by reaction with ozone (O3) and ammonium (NH3) gases within a newly developed gas to particle conversion device (GPD). The reaction mechanism of the gas to particle conversion is based on either oxidation of metal carbonyl gas by O3 or agglomeration of metal oxide with ammonium nitrate (NH4NO3) which is generated by the reaction of O3 and NH3. To separate the reaction gases (remaining O3 and NH3) from the formed particles, a previously reported gas exchange device (GED) was used and the in argon stabilized analyte particles were directly introduced and measured by ICPMS. This new technique provided limits of detection (LOD) of 0.15 pL L(-1) (0.32 ng m(-3)), 0.02 pL L(-1) (0.07 ng m(-3)), and 0.01 pL L(-1) (0.07 ng m(-3)) for Cr(CO)6, Mo(CO)6, and W(CO)6, respectively, which were 4-5 orders of magnitude lower than those conventional applied for detecting these gases, e.g., gas chromatography with electron captured detector (GC-ECD) as well as Fourier transform-infrared spectroscopy (FT-IR). The achieved LODs were also similar or slightly better than those for ICPMS coupled to GC. Since the gas to particle conversion technique can achieve the direct measurement of metal carbonyl gases as well as the removal of reaction and ambient gases from metal carbonyl gases, the technique is considered to be well suited to monitor gas quality in semiconductor industry, engine exhaust gases, and or waste incineration products. PMID:25247610

  13. A Novel Repair Technique for the Internal Thermal Control System Dual-Membrane Gas Trap

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Patel, Vipul; Reeves, Daniel R.; Holt, James M.

    2005-01-01

    A dual-membrane gas trap is currently used to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas trap was designed to last for the entire lifetime of the ISS, and therefore was not designed to be repaired. However, repair of these gas traps is now a necessity due to contamination from the on-orbit ITCS fluid and other sources on the ground as well as a limited supply of flight gas traps. This paper describes a novel repair technique that has been developed that will allow the refurbishment of contaminated gas traps and their return to flight use.

  14. Multiple inert gas elimination technique by micropore membrane inlet mass spectrometry--a comparison with reference gas chromatography.

    PubMed

    Kretzschmar, Moritz; Schilling, Thomas; Vogt, Andreas; Rothen, Hans Ulrich; Borges, João Batista; Hachenberg, Thomas; Larsson, Anders; Baumgardner, James E; Hedenstierna, Göran

    2013-10-15

    The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired gas exchange. The gold standard for measuring VA/Q distributions is based on measurements of the elimination and retention of infused inert gases. Conventional multiple inert gas elimination technique (MIGET) uses gas chromatography (GC) to measure the inert gas partial pressures, which requires tonometry of blood samples with a gas that can then be injected into the chromatograph. The method is laborious and requires meticulous care. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) facilitates the handling of blood and gas samples and provides nearly real-time analysis. In this study we compared MIGET by GC and MMIMS in 10 piglets: 1) 3 with healthy lungs; 2) 4 with oleic acid injury; and 3) 3 with isolated left lower lobe ventilation. The different protocols ensured a large range of normal and abnormal VA/Q distributions. Eight inert gases (SF6, krypton, ethane, cyclopropane, desflurane, enflurane, diethyl ether, and acetone) were infused; six of these gases were measured with MMIMS, and six were measured with GC. We found close agreement of retention and excretion of the gases and the constructed VA/Q distributions between GC and MMIMS, and predicted PaO2 from both methods compared well with measured PaO2. VA/Q by GC produced more widely dispersed modes than MMIMS, explained in part by differences in the algorithms used to calculate VA/Q distributions. In conclusion, MMIMS enables faster measurement of VA/Q, is less demanding than GC, and produces comparable results.

  15. Current Techniques of Growing Algae Using Flue Gas from Exhaust Gas Industry: a Review.

    PubMed

    Huang, Guanhua; Chen, Feng; Kuang, Yali; He, Huan; Qin, An

    2016-03-01

    The soaring increase of flue gas emission had caused global warming, environmental pollution as well as climate change. Widespread concern on reduction of flue gas released from industrial plants had considered the microalgae as excellent biological materials for recycling the carbon dioxide directly emitted from exhaust industries. Microalgae also have the potential to be the valuable feedback for renewable energy production due to their high growth rate and abilities to sequester inorganic carbon through photosynthetic process. In this review article, we will illustrate important relative mechanisms in the metabolic processes of biofixation by microalgae and their recent experimental researches and advances of sequestration of carbon dioxide by microalgae on actual industrial and stimulate flue gases, novel photobioreactor cultivation systems as well as the perspectives and limitations of microalgal cultivation in further development.

  16. [A Detection Technique for Gas Concentration Based on the Spectral Line Shape Function].

    PubMed

    Zhou, Mo; Yang, Bing-chu; Tao, Shao-hua

    2015-04-01

    The methods that can rapidly and precisely measure concentrations of various gases have extensive applications in the fields such as air quality analysis, environmental pollution detection, and so on. The gas detection method based on the tunable laser absorption spectroscopy is considered a promising technique. For the infrared spectrum detection techniques, the line shape function of an absorption spectrum of a gas is an important parameter in qualitative and quantitative analysis of a gas. Specifically, how to obtain the line shape function of an absorption spectrum of a gas quickly and accurately is a key problem in the gas detection fields. In this paper we analyzed several existing line shape functions and proposed a method to calculate precisely the line shape function of a gas, and investigated the relation between the gas concentration and the peak value of a line shape function. Then we experimentally measured the absorption spectra of an acetylene gas in the wavelength range of 1,515-1,545 nm with a tunable laser source and a built-in spectrometer. With Lambert-Beer law we calculated the peak values of the line shape function of the gas at the given frequencies, and obtained a fitting curve for the line shape function in the whole waveband by using a computer program. Comparing the measured results with the calculated results of the Voigt function, we found that there was a deviation-between the experimental results and the calculated results. And we found that the measured concentration of the acetylene gas by using the fitting curve of the line shape function was more accurate and compatible with the actual situation. Hence, the empirical formula for the line shape function obtained from the experimental results would be more suitable for the concentration measurement of a gas. As the fitting curve for the line shape function of the acetylene gas has been deduced from the experiment, the corresponding peak values of the spectral lines can be

  17. Residual solvent testing: a review of gas-chromatographic and alternative techniques.

    PubMed

    B'Hymer, Clayton

    2003-03-01

    The purpose of this brief review is to describe and discuss some of the current analytic procedures including gas-chromatographic and alternative techniques for residual solvent testing. Residual solvents, or organic volatile impurities, are a potential toxic risk for pharmaceutic products and have been a concern of manufacturers for many years. Residual solvents have had official limits in the United States as set in USP XXV and by the FDA in 1997 and have been monitored by most pharmaceutical manufacturers extensively for more than two decades in both bulk and finished products. The chief method of analysis for residual solvents is gas chromatography, which is generally considered the preferred methodology. Sample introduction techniques include both static and dynamic headspace analysis, solid-phase microextraction, and direct injection of solution containing bulk drug substance or drug product into the gas chromatograph. Also, some alternative methodologies for residual solvent testing are discussed in this review. In conclusion, gas chromatograph-based procedures will continue to dominate residual solvent testing because of its specificity for identification of the solvent, but the use of alternative sample introduction techniques into a gas chromatograph will continue to expand in the near future.

  18. Contribution of multiple inert gas elimination technique to pulmonary medicine. 1. Principles and information content of the multiple inert gas elimination technique.

    PubMed Central

    Roca, J.; Wagner, P. D.

    1994-01-01

    This introductory review summarises four different aspects of the multiple inert gas elimination technique (MIGET). Firstly, the historical background that facilitated, in the mid 1970s, the development of the MIGET as a tool to obtain more information about the entire spectrum of VA/Q distribution in the lung by measuring the exchange of six gases of different solubility in trace concentrations. Its principle is based on the observation that the retention (or excretion) of any gas is dependent on the solubility (lambda) of that gas and the VA/Q distribution. A second major aspect is the analysis of the information content and limitations of the technique. During the last 15 years a substantial amount of clinical research using the MIGET has been generated by several groups around the world. The technique has been shown to be adequate in understanding the mechanisms of hypoxaemia in different forms of pulmonary disease and the effects of therapeutic interventions, but also in separately determining the quantitative role of each extrapulmonary factor on systemic arterial PO2 when they change between two conditions of MIGET measurement. This information will be extensively reviewed in the forthcoming articles of this series. Next, the different modalities of the MIGET, practical considerations involved in the measurements and the guidelines for quality control have been indicated. Finally, a section has been devoted to the analysis of available data in healthy subjects under different conditions. The lack of systematic information on the VA/Q distributions of older healthy subjects is emphasised, since it will be required to fully understand the changes brought about by diseases that affect the older population. PMID:8091330

  19. Detection of localized cable damage using a preionized gas technique. Final report

    SciTech Connect

    Vigil, R.A.; Jacobus, M.J.; Bustard, L.

    1994-10-01

    Because of the absence of a nearby, well-defined ground plane, performing electrical tests on unshielded cables installed in conduits is difficult. Experiments were run to develop a preionized gas troubleshooting technique to detect localized degradation of unshielded cables in conduits. This was achieved by introducing a readily ionizable gas like helium (or argon) in the conduit air space and then applying a moderately high voltage to the test cable, thus ionizing the gas surrounding the cable. Breakdown testing was performed on various types of damaged and undamaged cables. Other parameters necessary for practical implementation of the technique were also examined, including gas type, position of the cable with respect to the conduit wall, length of cable, conduit configuration, conduit size, and gas propagation in conduits. High potential testing of cables in the presence of preionized helium gas provides essentially the same information as high potential testing in water. A test criterion of 30 kVdc or 10 kVac would detect when 5-mils of insulation remain on one particular tested cable. No undamaged cable was noted to break down at these voltages. A high concentration of helium is required to perform the test, but this is easily attained with straightforward preparations. A cable with through-wall damage can easily be detected with a test criterion of approximately 1.5 kvac.

  20. Accuracy of vertical radial plume mapping technique in measuring lagoon gas emission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently, the U.S. Environmental Protection Agency (USEPA) posted a ground-based optical remote sensing method on its website called OTM 10 for measuring fugitive gas emission flux from area sources such as closed landfills. The OTM 10 utilizes the vertical radial plume mapping (VRPM) technique to c...

  1. Mississippi exploration field trials using microbial, radiometrics, free soil gas, and other techniques

    SciTech Connect

    Moody, J.S.; Brown, L.R.; Thieling, S.C.

    1995-12-31

    The Mississippi Office of Geology has conducted field trials using the surface exploration techniques of geomicrobial, radiometrics, and free soil gas. The objective of these trials is to determine if Mississippi oil and gas fields have surface hydrocarbon expression resulting from vertical microseepage migration. Six fields have been surveyed ranging in depth from 3,330 ft to 18,500 ft. The fields differ in trapping styles and hydrocarbon type. The results so far indicate that these fields do have a surface expression and that geomicrobial analysis as well as radiometrics and free soil gas can detect hydrocarbon microseepage from pressurized reservoirs. All three exploration techniques located the reservoirs independent of depth, hydrocarbon type, or trapping style.

  2. Application of the can technique and radon gas analyzer for radon exhalation measurements.

    PubMed

    Fazal-ur-Rehman; Al-Jarallah, M I; Musazay, M S; Abu-Jarad, F

    2003-01-01

    A passive "can technique" and an active radon gas analyzer with an emanation container were applied for radon exhalation rate measurements from different construction materials, viz. five marble seven ceramic and 100 granite tiles used in Saudi Arabia. The marble and ceramic tiles did not show detectable radon exhalation using the active radon gas analyzer system. However the granite tiles showed relatively high radon exhalations, indicating a relatively high uranium content. A comparison of the radon exhalation rates measured by the two techniques showed a linear correlation coefficient of 0.57. The radon exhalation rates from the granites varied from 0.02 to 6.58 Bqm(-2)h(-1) with an average of 1.35+/-1.40 Bqm(-2)h(-1). The geometric mean and the geometric standard deviation of the frequency distribution were found to be 0.80 and 3.1, respectively. The track density found on the nuclear track detectors in the can technique exposed to the granites, having high exhalation rates, varied linearly with exposure time with a linear correlation coefficient of 0.99. This experimental finding agrees with the theoretical prediction. The can technique showed sensitivity to low radon exhalation rates from ceramic, marble and some granite over a period of 2 months, which were not detectable by the active radon gas analyzer system. The reproducibility of data with both measuring techniques was found to be within a 7% deviation.

  3. Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique.

    PubMed

    Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef

    2015-09-01

    An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air.

  4. Molecular Rayleigh Scattering Techniques Developed for Measuring Gas Flow Velocity, Density, Temperature, and Turbulence

    NASA Technical Reports Server (NTRS)

    Mielke, Amy F.; Seasholtz, Richard G.; Elam, Kristie A.; Panda, Jayanta

    2005-01-01

    Nonintrusive optical point-wise measurement techniques utilizing the principles of molecular Rayleigh scattering have been developed at the NASA Glenn Research Center to obtain time-averaged information about gas velocity, density, temperature, and turbulence, or dynamic information about gas velocity and density in unseeded flows. These techniques enable measurements that are necessary for validating computational fluid dynamics (CFD) and computational aeroacoustic (CAA) codes. Dynamic measurements allow the calculation of power spectra for the various flow properties. This type of information is currently being used in jet noise studies, correlating sound pressure fluctuations with velocity and density fluctuations to determine noise sources in jets. These nonintrusive techniques are particularly useful in supersonic flows, where seeding the flow with particles is not an option, and where the environment is too harsh for hot-wire measurements.

  5. Measuring Buffer-Gas Pressure in Sealed Glass Cells: An Assessment of the KSK Technique.

    PubMed

    Driskell, Travis; Huang, Michael; Camparo, James

    2016-07-01

    In alkali rf-discharge lamps used for optical pumping in atomic clocks and magnetometers, a buffer-gas (Kr or Xe) allows electrons to extract energy from an rf-field, and these energized electrons eventually produce alkali resonant light. Contrary to naïve intuition, rf-discharge lamps can lose their noble-gas buffer over time. Recently, we began a long-term experimental program to better understand the mechanism of noble-gas loss in rf-discharge lamps, and needed a nondestructive means of measuring buffer-gas pressure changes in sealed glass cells. For this purpose, we settled on the Kazantsev, Smirnova, and Khutorshchikov (KSK) technique, which is based on inferring buffer-gas pressure from the collision shift of an alkali ground-state hyperfine transition frequency νhfs. Here, we discuss the basic KSK technique and two modifications that we have implemented for its improvement: use of a diode laser for optical pumping, and extrapolation of νhfs to zero magnetic field. Testing our system's long-term performance with a very low pressure reference cell (i.e., 3.3 torr Xe), we find a reproducibility of 0.2% and an absolute accuracy of 5%. Further, our systematic drift is less than 1 mtorr/month. PMID:26529755

  6. Measuring Buffer-Gas Pressure in Sealed Glass Cells: An Assessment of the KSK Technique.

    PubMed

    Driskell, Travis; Huang, Michael; Camparo, James

    2016-07-01

    In alkali rf-discharge lamps used for optical pumping in atomic clocks and magnetometers, a buffer-gas (Kr or Xe) allows electrons to extract energy from an rf-field, and these energized electrons eventually produce alkali resonant light. Contrary to naïve intuition, rf-discharge lamps can lose their noble-gas buffer over time. Recently, we began a long-term experimental program to better understand the mechanism of noble-gas loss in rf-discharge lamps, and needed a nondestructive means of measuring buffer-gas pressure changes in sealed glass cells. For this purpose, we settled on the Kazantsev, Smirnova, and Khutorshchikov (KSK) technique, which is based on inferring buffer-gas pressure from the collision shift of an alkali ground-state hyperfine transition frequency νhfs. Here, we discuss the basic KSK technique and two modifications that we have implemented for its improvement: use of a diode laser for optical pumping, and extrapolation of νhfs to zero magnetic field. Testing our system's long-term performance with a very low pressure reference cell (i.e., 3.3 torr Xe), we find a reproducibility of 0.2% and an absolute accuracy of 5%. Further, our systematic drift is less than 1 mtorr/month.

  7. Underwater-seal nasogastric tube drainage to relieve gastric distension caused by air swallowing.

    PubMed

    Solomon, A W; Bramall, J C; Ball, J

    2011-02-01

    Air swallowing can occur as a psychogenic phenomenon, because of abnormal anatomy, or during non-invasive positive pressure ventilation. Gross distension of the stomach with air can have severe consequences for the respiratory and gastrointestinal systems. We report the case of a 62-year-old man with severe dynamic hyperinflation due to chronic obstructive pulmonary disease, who developed respiratory failure requiring intubation a few hours after radical prostatectomy. Following a percutaneous tracheostomy and weaning of sedation on day six, his abdomen began to enlarge progressively. X-rays revealed massive gastric distension due to air swallowing, which continued despite all efforts to optimise therapy. The use of an underwater seal drainage system on a nasogastric tube improved ventilation and ultimately aided weaning from mechanical support.

  8. Microwave interferometry technique for obtaining gas interface velocity measurements in an expansion tube facility

    NASA Technical Reports Server (NTRS)

    Laney, C. C., Jr.

    1974-01-01

    A microwave interferometer technique to determine the front interface velocity of a high enthalpy gas flow, is described. The system is designed to excite a standing wave in an expansion tube, and to measure the shift in this standing wave as it is moved by the test gas front. Data, in the form of a varying sinusoidal signal, is recorded on a high-speed drum camera-oscilloscope combination. Measurements of average and incremental velocities in excess of 6,000 meters per second were made.

  9. Role of the gas flow parameters on the uniformity of films produced by PECVD technique

    SciTech Connect

    Martins, R.; Macarico, A.; Ferreira, I.; Fortunato, E.

    1997-07-01

    The aim of this work is to present an analytical model able to interpret the experimental data of the dependence of film's uniformity on the discharge pressure, gas flow and temperature used during the production of thin films by the plasma enhancement chemical vapor deposition technique, under optimized electrode's geometry and electric field distribution. To do so, the gas flow is considered to be quasi-incompressible and inviscous leading to the establishment of the electro-fluid-mechanics equations able to interpret the film's uniformity over the substrate area, when the discharge process takes place in the low power regime.

  10. The aging process modifies the distensibility of elastic but not muscular arteries.

    PubMed

    Bortolotto, L A; Hanon, O; Franconi, G; Boutouyrie, P; Legrain, S; Girerd, X

    1999-10-01

    Aging decreases the distensibility of large elastic arteries; however, the effects of age on the functional parameters of muscular, medium-sized arteries are not well determined. This study evaluated the consequences of aging on the functional parameters of the carotid and radial arteries in normotensive men. A total of 62 elderly subjects (aged 74+/-2 years) were compared with 87 young subjects (aged 35+/-3 years). Internal diameter and intima-media thickness (IMT) were measured by a high-resolution echo-tracking system to calculate distensibility and incremental elastic modulus (Einc). Although in the normal range, systolic and diastolic blood pressure levels were statistically different in the 2 groups at 128+/-19 and 74+/-13 mm Hg versus 121+/-27 and 71+/-18 mm Hg in the young and elderly subjects, respectively (P<0.05). At the carotid artery level, elderly subjects exhibited a greater IMT (742+/-144 versus 469+/-132 microm; P<0.01) and internal diameter (7067+/-828 versus 6062+/-1026 microm; P<0.01) than young subjects; elderly subjects also had lower distensibility (12+/-2 versus 21+/-2 kPa(-1) x 10(-3); P<0.01) and higher Einc (0.9+/-0.2 versus 0.7+/-0.3 kPa x 10(3); P<0.01). At the radial artery level, both IMT (240+/-42 versus 218+/-51 microm; P<0.01) and internal diameter (2685+/-432 versus 2491+/-444 microm; P<0.01) were greater in elderly subjects, but no differences in distensibility and Einc were observed between the 2 groups. All differences remained significant, even after adjusting for mean blood pressure. These results indicate that the increase of the internal diameter and IMT observed during the aging process can have opposite effects on the functional parameters of large elastic or medium-sized muscular arteries.

  11. Repeated Gastric Distension Alters Food Intake and Neuroendocrine Profiles in Rats

    PubMed Central

    Hargrave, Sara L.; Kinzig, Kimberly P.

    2011-01-01

    The consumption of a large food bolus leads to stomach distension. Gastric distension potently signals the termination of a meal by stimulating gastric mechanoreceptors and activating neuroendocrine circuitry. The ability to terminate a meal is altered in disorders such as bulimia nervosa (BN), binge-eating disorder (BED) and certain subtypes of obesity in which large quantities of food are frequently ingested. When a large meal is consumed, the stomach is rapidly stretched. We modeled this rapid distension of the stomach in order to determine if the neuroendocrine abnormalities present in these disorders, including increased gastric capacit3y, leptin dysregulation, and alterations in neuropeptide Y (NPY), and proopiomelanocortin (POMC) expression, were influenced by the rapid stretch aspect of repeatedly consuming a large meal. To test the effects of repeated gastric distension (RGD) on neuroendocrine factors involved in energy homeostasis, a permanent intra-gastric balloon was implanted in rats, and briefly inflated daily for 4 weeks. Though body weights and daily food intakes remained equivalent in RGD and control rats, a significant delay in the onset of feeding was present during the first and second, but not the third and fourth weeks of inflations. Despite equivalent body weights and daily caloric consumption, RGD animals had significantly decreased leptin levels (p < 0.05), and tended to have increased fasting arcuate NPY levels (p = 0.08), which were suppressed more than control animals following food intake (control and RGD decreases from baseline were 184.95% and 257.42%, respectively). NPY expression in the nucleus of the solitary tract followed a similar pattern. These data demonstrate that the act of regularly distending the stomach can have effects on the regulation of energy balance that are independent from those related to caloric consumption, and may be related to disorders such as BN, BED, and certain types of obesity in which meal termination

  12. Antinociceptive action against colonic distension by brain orexin in conscious rats.

    PubMed

    Okumura, Toshikatsu; Nozu, Tsukasa; Kumei, Shima; Takakusaki, Kaoru; Miyagishi, Saori; Ohhira, Masumi

    2015-02-19

    Increasing evidence has suggested that brain orexins are implicated in a wide variety of physiological functions. With regard to gastrointestinal functions, orexin-A acts centrally to regulate gastrointestinal functions such as gastric and pancreatic secretion, and gastrointestinal motility. Visceral sensation is also known as one of key gastrointestinal functions which are controlled by the central nervous system. Little is, however, known about a role of central orexin in visceral sensation. This study was therefore performed to clarify whether brain orexin may be involved in the process of visceral sensation. Visceral sensation was evaluated by colonic distension-induced abdominal withdrawal reflex (AWR) in conscious rats. Intracisternally administered orexin-A dose-dependently increased the threshold volume of colonic distension-induced AWR. In contrast, neither intraperitoneal injection of orexin-A nor intracisternal orexin-B altered the threshold volume. While intracisternal SB334867, an orexin 1 receptor antagonist, by itself failed to change the threshold volume, SB334867 injected centrally completely blocked the morphine-induced antinociceptive action against colonic distension. These results suggest for the first time that orexin-A specifically acts centrally in the brain to enhance antinociceptive response to colonic distension. We would furthermore suggest that endogenous orexin-A indeed mediates the antinociceptive effect of morphine on visceral sensation through the orexin 1 receptors. All these evidence might indicate that brain orexin plays a role in the pathophysiology of functional gastrointestinal disorders such as irritable bowel syndrome because visceral hypersensitivity of the gut is considered to play a vital role in the diseases.

  13. Primary distension of the guttural pouch lateral compartment secondary to empyema.

    PubMed Central

    Smyth, D A; Baptiste, K E; Cruz, A M; Naylor, J M

    1999-01-01

    A 6-year-old, 420-kg quarter horse gelding was presented with a 2-month history of difficulty swallowing and dyspnea. The horse was diagnosed with a right guttural pouch empyema with many large chondroids. Two surgeries were required to completely remove all the chondroids from what proved to be a primary distension of the guttural pouch lateral compartment. Images Figure 1. Figure 2. PMID:10563241

  14. Developing Repair Materials for Stress Urinary Incontinence to Withstand Dynamic Distension

    PubMed Central

    Hillary, Christopher J.; Roman, Sabiniano; Bullock, Anthony J.; Green, Nicola H; Chapple, Christopher R.; MacNeil, Sheila

    2016-01-01

    Background Polypropylene mesh used as a mid-urethral sling is associated with severe clinical complications in a significant minority of patients. Current in vitro mechanical testing shows that polypropylene responds inadequately to mechanical distension and is also poor at supporting cell proliferation. Aims and Objectives Our objective therefore is to produce materials with more appropriate mechanical properties for use as a sling material but which can also support cell integration. Methods Scaffolds of two polyurethanes (PU), poly-L-lactic acid (PLA) and co-polymers of the two were produced by electrospinning. Mechanical properties of materials were assessed and compared to polypropylene. The interaction of adipose derived stem cells (ADSC) with the scaffolds was also assessed. Uniaxial tensiometry of scaffolds was performed before and after seven days of cyclical distension. Cell penetration (using DAPI and a fluorescent red cell tracker dye), viability (AlamarBlue assay) and total collagen production (Sirius red assay) were measured for ADSC cultured on scaffolds. Results Polypropylene was stronger than polyurethanes and PLA. However, polypropylene mesh deformed plastically after 7 days of sustained cyclical distention, while polyurethanes maintained their elasticity. Scaffolds of PU containing PLA were weaker and stiffer than PU or polypropylene but were significantly better than PU scaffolds alone at supporting ADSC. Conclusions Therefore, prolonged mechanical distension in vitro causes polypropylene to fail. Materials with more appropriate mechanical properties for use as sling materials can be produced using PU. Combining PLA with PU greatly improves interaction of cells with this material. PMID:26981860

  15. Monte Carlo uncertainty analyses of a bLS inverse-dispersion technique for measuring gas emissions from livestock operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The backward Lagrangian stochastic (bLS) inverse-dispersion technique has been used to measure fugitive gas emissions from livestock operations. The accuracy of the bLS technique, as indicated by the percentages of gas recovery in various tracer-release experiments, has generally been within ± 10% o...

  16. Unusual well control techniques pay off. [Well drilling techniques in the Elgin gas condensate field, North Sea

    SciTech Connect

    Idelovici, J.L.

    1993-07-01

    Well control and completion operations were seriously complicated by an unusual pressure phenomena encountered while drilling an appraisal well through Jurassic sandstones in a high-pressure, high-temperature (HPHT), gas and condensate field located in the United Kingdom continental shelf. The HPHT sandstone reservoir is located in the Upper Jurassic Franklin formation. Unorthodox well-control techniques were used because it was determined that the abnormally high pressure was generated by a mechanical reaction of the rock under the effect of heavy mud and equivalent circulating density, rather than by entry into the wellbore of formation fluids. This paper reviews the complex drilling fluid control procedures which had to be utilized to maintain an open bore hole during drilling.

  17. Development of an in situ calibration technique for combustible gas detectors

    NASA Technical Reports Server (NTRS)

    Shumar, J. W.; Wynveen, R. A.; Lance, N., Jr.; Lantz, J. B.

    1977-01-01

    This paper describes the development of an in situ calibration procedure for combustible gas detectors (CGD). The CGD will be a necessary device for future space vehicles as many subsystems in the Environmental Control/Life Support System utilize or produce hydrogen (H2) gas. Existing calibration techniques are time-consuming and require support equipment such as an environmental chamber and calibration gas supply. The in situ calibration procedure involves utilization of a water vapor electrolysis cell for the automatic in situ generation of a H2/air calibration mixture within the flame arrestor of the CGD. The development effort concluded with the successful demonstration of in situ span calibrations of a CGD.

  18. Sabots, Obturator and Gas-In-Launch Tube Techniques for Heat Flux Models in Ballistic Ranges

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.; Wilder, Michael C.

    2013-01-01

    For thermal protection system (heat shield) design for space vehicle entry into earth and other planetary atmospheres, it is essential to know the augmentation of the heat flux due to vehicle surface roughness. At the NASA Ames Hypervelocity Free Flight Aerodynamic Facility (HFFAF) ballistic range, a campaign of heat flux studies on rough models, using infrared camera techniques, has been initiated. Several phenomena can interfere with obtaining good heat flux data when using this measuring technique. These include leakage of the hot drive gas in the gun barrel through joints in the sabot (model carrier) to create spurious thermal imprints on the model forebody, deposition of sabot material on the model forebody, thereby changing the thermal properties of the model surface and unknown in-barrel heating of the model. This report presents developments in launch techniques to greatly reduce or eliminate these problems. The techniques include the use of obturator cups behind the launch package, enclosed versus open front sabot designs and the use of hydrogen gas in the launch tube. Attention also had to be paid to the problem of the obturator drafting behind the model and impacting the model. Of the techniques presented, the obturator cups and hydrogen in the launch tube were successful when properly implemented

  19. Fabrication of uniformly cell-laden porous scaffolds using a gas-in-liquid templating technique.

    PubMed

    Takei, Takayuki; Aokawa, Ryuta; Shigemitsu, Takamasa; Kawakami, Koei; Yoshida, Masahiro

    2015-11-01

    Design of porous scaffolds in tissue engineering field was challenging. Uniform immobilization of cells in the scaffolds with high porosity was essential for homogeneous tissue formation. The present study was aimed at fabricating uniformly cell-laden porous scaffolds with porosity >74% using the gas-in-liquid foam templating technique. To this end, we used gelatin, microbial transglutaminase and argon gas as a scaffold material, cross-linker of the protein and porogen of scaffold, respectively. We confirmed that a porosity of >74% could be achieved by increasing the gas volume delivered to a gelatin solution. Pore size in the scaffold could be controlled by stirring speed, stirring time and the pore size of the filter through which the gas passed. The foaming technique enabled us to uniformly immobilize a human hepatoblastoma cell line in scaffold. Engraftment efficiency of the cell line entrapped within the scaffold in nude mice was higher than that of cells in free-form. These results showed that the uniformly cell-laden porous scaffolds were promising for tissue engineering.

  20. Inverse gas chromatography and other chromatographic techniques in the examination of engine oils.

    PubMed

    Fall, Jacek; Voelkel, Adam

    2002-09-01

    The emerging market of engine oils consists of a number of products from different viscosity and quality classes. Determination of the base oil used in manufacturing of the final product (engine oil) as well as estimation of mutual miscibility of oils and their solubility could be crucial problems. Inverse gas chromatography and other chromatographic techniques are presented as an interesting and fruitful extension of normalised standard analytical methods used in the oil industry. PMID:12385390

  1. Esophagogastric junction distensibility measurements during Heller myotomy and POEM for achalasia predict postoperative symptomatic outcomes

    PubMed Central

    Teitelbaum, Ezra N.; Soper, Nathaniel J.; Pandolfino, John E.; Kahrilas, Peter J.; Hirano, Ikuo; Boris, Lubomyr; Nicodème, Frédéric; Lin, Zhiyue; Hungness, Eric S.

    2015-01-01

    Background The functional lumen imaging probe (FLIP) is a novel diagnostic tool that can be used to measure esophagogastric junction (EGJ) distensibility. In this study we performed intraoperative FLIP measurements during laparoscopic Heller myotomy (LHM) and peroral esophageal myotomy (POEM) for treatment of achalasia and evaluated the relationship between EGJ distensibility and postoperative symptoms. Methods Distensibility index (DI) (defined as the minimum cross-sectional area at the EGJ divided by distensive pressure) was measured with FLIP at two time points during LHM and POEM: 1) at baseline after induction of anesthesia, and 2) after operation completion. Results Measurements were performed in 20 patients undergoing LHM and 36 undergoing POEM. Both operations resulted in an increase in DI, although this increase was larger with POEM (7±3.1 vs. 5.1±3.4mm2/mmHg, p<.05). The two patients (both LHM) with the smallest increases in DI (1 and 1.6mm2/mmHg) both had persistent symptoms postoperatively and, overall, LHM patients with larger increases in DI had lower postoperative Eckardt scores. In the POEM group, there was no correlation between change in DI and symptoms; however, all POEM patients experienced an increase in DI of >3mm2/mmHg. When all patients were divided into thirds based on final DI, none in the lowest DI group (<6mm2/mmHg) had symptoms suggestive of reflux (i.e., GerdQ score >7), as compared with 20% in the middle third (6–9mm2/mmHg) and 36% in the highest third (>9mm2/mmHg). Patients within an “ideal” final DI range (4.5–8.5 mm2/mmHg) had optimal symptomatic outcomes (i.e. Eckardt≤1 and GerdQ≤7) in 88% of cases, compared with 47% in those with a final DI above or below that range (p<.05). Conclusions Intraoperative EGJ distensibility measurements with FLIP were predictive of postoperative symptomatic outcomes. These results provide initial evidence that FLIP has the potential to act as a useful calibration tool during operations

  2. Distensibility and Strength of the Pelvic Floor Muscles of Women in the Third Trimester of Pregnancy

    PubMed Central

    Petricelli, Carla Dellabarba; Resende, Ana Paula Magalhães; Elito Júnior, Julio; Araujo Júnior, Edward; Alexandre, Sandra Maria; Zanetti, Miriam Raquel Diniz; Nakamura, Mary Uchiyama

    2014-01-01

    Objective. The objective of this study was to compare the role of the pelvic floor muscles between nulliparous and multiparous women in the third trimester of pregnancy, by analyzing the relationship between electrical activity (surface electromyography—EMG), vaginal palpation (modified Oxford scale), and perineal distensibility (Epi-no). Methods. This was an observational cross-sectional study on a sample of 60 healthy pregnant women with no cervical dilation, single fetus, gestational age between 35 and 40 weeks, and maternal age ranging from 15 to 40 years. The methods used were bidigital palpation (modified Oxford scale, graded 0–5), surface EMG (electrical activity during maximal voluntary contraction), and perineal distensibility (Epi-no device). The Pearson correlation coefficient (r) was used to analyze the Epi-no values and the surface EMG findings. The Kruskal-Wallis test was used to compare the median values from surface EMG and Epi-no, using the modified Oxford scale scores. Results. Among the 60 patients included in this study, 30 were nulliparous and 30 multiparous. The average maternal age and gestational age were 26.06 (±5.58) and 36.56 (±1.23), respectively. It was observed that nulliparous women had both higher perineal muscle strength (2.53 ± 0.57 versus 2.06 ± 0.64; P = 0.005) and higher electrical activity (45.35 ± 12.24 μV versus 35.79 ± 11.66 μV; P = 0.003), while among the multiparous women, distensibility was higher (19.39 ± 1.92 versus 18.05 ± 2.14; P = 0.013). We observed that there was no correlation between perineal distensibility and electrical activity during maximal voluntary contraction (r = − 0.193; P = 0.140). However, we found a positive relationship between vaginal palpation and surface electromyography (P = 0.008), but none between Epi-no values (P = 0.785). Conclusion. The electrical activity and muscle strength of the pelvic floor muscles of the multiparous women were damaged, in relation to the

  3. Characterization techniques for gas diffusion layers for proton exchange membrane fuel cells - A review

    NASA Astrophysics Data System (ADS)

    Arvay, A.; Yli-Rantala, E.; Liu, C.-H.; Peng, X.-H.; Koski, P.; Cindrella, L.; Kauranen, P.; Wilde, P. M.; Kannan, A. M.

    2012-09-01

    The gas diffusion layer (GDL) in a proton exchange membrane fuel cell (PEMFC) is one of the functional components that provide a support structure for gas and water transport. The GDL plays a crucial role when the oxidant is air, especially when the fuel cell operates in the higher current density region. There has been an exponential growth in research and development because the PEMFC has the potential to become the future energy source for automotive applications. In order to serve in this capacity, the GDL requires due innovative analysis and characterization toward performance and durability. It is possible to achieve the optimum fuel cell performance only by understanding the characteristics of GDLs such as structure, pore size, porosity, gas permeability, wettability, thermal and electrical conductivities, surface morphology and water management. This review attempts to bring together the characterization techniques for the essential properties of the GDLs as handy tools for R&D institutions. Topics are categorized based on the ex-situ and in-situ characterization techniques of GDLs along with related modeling and simulation. Recently reported techniques used for accelerated durability evaluation of the GDLs are also consolidated within the ex-situ and in-situ methods.

  4. Towards the development of rapid screening techniques for shale gas core properties

    NASA Astrophysics Data System (ADS)

    Cave, Mark R.; Vane, Christopher; Kemp, Simon; Harrington, Jon; Cuss, Robert

    2013-04-01

    Shale gas has been produced for many years in the U.S.A. and forms around 8% of total their natural gas production. Recent testing for gas on the Fylde Coast in Lancashire UK suggests there are potentially large reserves which could be exploited. The increasing significance of shale gas has lead to the need for deeper understanding of shale behaviour. There are many factors which govern whether a particular shale will become a shale gas resource and these include: i) Organic matter abundance, type and thermal maturity; ii) Porosity-permeability relationships and pore size distribution; iii) Brittleness and its relationship to mineralogy and rock fabric. Measurements of these properties require sophisticated and time consuming laboratory techniques (Josh et al 2012), whereas rapid screening techniques could provide timely results which could improve the efficiency and cost effectiveness of exploration. In this study, techniques which are portable and provide rapid on-site measurements (X-ray Fluorescence (XRF) and Infra-red (IR) spectroscopy) have been calibrated against standard laboratory techniques (Rock-Eval 6 analyser-Vinci Technologies) and Powder whole-rock XRD analysis was carried out using a PANalytical X'Pert Pro series diffractometer equipped with a cobalt-target tube, X'Celerator detector and operated at 45kV and 40mA, to predict properties of potential shale gas material from core material from the Bowland shale Roosecote, south Cumbria. Preliminary work showed that, amongst various mineralogical and organic matter properties of the core, regression models could be used so that the total organic carbon content could be predicted from the IR spectra with a 95 percentile confidence prediction error of 0.6% organic carbon, the free hydrocarbons could be predicted with a 95 percentile confidence prediction error of 0.6 mgHC/g rock, the bound hydrocarbons could be predicted with a 95 percentile confidence prediction error of 2.4 mgHC/g rock, mica content

  5. Adaptive polynomial chaos techniques for uncertainty quantification of a gas cooled fast reactor transient

    SciTech Connect

    Perko, Z.; Gilli, L.; Lathouwers, D.; Kloosterman, J. L.

    2013-07-01

    Uncertainty quantification plays an increasingly important role in the nuclear community, especially with the rise of Best Estimate Plus Uncertainty methodologies. Sensitivity analysis, surrogate models, Monte Carlo sampling and several other techniques can be used to propagate input uncertainties. In recent years however polynomial chaos expansion has become a popular alternative providing high accuracy at affordable computational cost. This paper presents such polynomial chaos (PC) methods using adaptive sparse grids and adaptive basis set construction, together with an application to a Gas Cooled Fast Reactor transient. Comparison is made between a new sparse grid algorithm and the traditionally used technique proposed by Gerstner. An adaptive basis construction method is also introduced and is proved to be advantageous both from an accuracy and a computational point of view. As a demonstration the uncertainty quantification of a 50% loss of flow transient in the GFR2400 Gas Cooled Fast Reactor design was performed using the CATHARE code system. The results are compared to direct Monte Carlo sampling and show the superior convergence and high accuracy of the polynomial chaos expansion. Since PC techniques are easy to implement, they can offer an attractive alternative to traditional techniques for the uncertainty quantification of large scale problems. (authors)

  6. New seismic reflection techniques applied to gas recognition in the Rharb Basin, Morocco

    SciTech Connect

    Jabour, H.; Dakki, M. )

    1994-07-01

    The Rharb basin in Morocco is a Tertiary foreland filled by clastic series during the Miocene and Pliocene. This terrigenous influx, derived from the prerif to the northeast and the Meseta to the south, is characterized by a sandy episode during much of the Messinian and the Tortonian. The sand deposits were probably related to the uplift and major erosion of a part of the prerif during the sliding of an olistostrome (prerif nappe). Although most of the wells drilled in the basin have encountered biogenic gas accumulations, the problem still facing exploration in the area is seismic resolution and thin-bed tuning analysis. Recent studies using high seismic resolution techniques have permitted the authors to gain a deep insight into the stratigraphy and depositional environment of the thin sand reservoirs and their fluid content. AVO stratigraphy, inversion of seismic traces into acoustic impedance traces and seismic attributes calculation, and computing provide a remarkable example of the possibilities of depicting the lateral and vertical evolution of reservoir facies and localizing biogenic gas accumulations. Out of five recent exploratory wells drilled based on this new technique, three encountered gas-bearing sands with economic potential. Fifty-three amplitude anomalies have been identified and await processing.

  7. Carotid artery intima-media thickness and distensibility in children and adolescents: reference values and role of body dimensions.

    PubMed

    Doyon, Anke; Kracht, Daniela; Bayazit, Aysun K; Deveci, Murat; Duzova, Ali; Krmar, Rafael T; Litwin, Mieczyslaw; Niemirska, Anna; Oguz, Berna; Schmidt, Bernhard M W; Sözeri, Betul; Querfeld, Uwe; Melk, Anette; Schaefer, Franz; Wühl, Elke

    2013-09-01

    Carotid intima-media thickness (cIMT) and carotid artery distensibility are reliable screening methods for vascular alterations and the assessment of cardiovascular risk in adult and pediatric cohorts. We sought to establish an international reference data set for the childhood and adolescence period and explore the impact of developmental changes in body dimensions and blood pressure (BP) on carotid wall thickness and elasticity. cIMT, the distensibility coefficient, the incremental modulus of elasticity, and the stiffness index β were assessed in 1155 children aged 6 to 18 years and sex-specific reference charts normalized to age or height were constructed from 1051 nonobese and nonhypertensive children. The role of body dimensions, BP, and family history, as well as the association between cIMT and distensibility, was investigated. cIMT increased and distensibility decreased with age, height, body mass index, and BP. A significant sex difference was apparent from the age of 15 years. Age- and height-normalized cIMT and distensibility values differed in children who are short or tall for their age. By stepwise multivariate analysis, standardized systolic BP and body mass index were independently positively associated with cIMT SD scores (SDS). Systolic BP SDS independently predicted all distensibility measures. Distensibility coefficient SDS was negatively and β SDS positively associated with cIMT SDS, whereas incremental modulus of elasticity was independent of cIMT. Morphological and functional aspects of the common carotid artery are particularly influenced by age, body dimensions, and BP. The reference charts established in this study allow to accurately compare vascular phenotypes of children with chronic conditions with those of healthy children.

  8. Estimating the gas and dye quantities for modified tracer technique measurements of stream reaeration coefficients

    USGS Publications Warehouse

    Rathbun, R.E.

    1979-01-01

    Measuring the reaeration coefficient of a stream with a modified tracer technique has been accomplished by injecting either ethylene or ethylene and propane together and a rhodamine-WT dye solution into the stream. The movement of the tracers through the stream reach after injection is described by a one-dimensional diffusion equation. The peak concentrations of the tracers at the downstream end of the reach depend on the concentrations of the tracers in the stream at the injection site, the longitudinal dispersion coefficient, the mean water velocity, the length of the reach, and the duration of the injection period. The downstream gas concentrations also depend on the gas desorption coefficients of the reach. The concentrations of the tracer gases in the stream at the injection site depend on the flow rates of the gases through the injection diffusers, the efficiency of the gas absorption process, and the stream discharge. The concentration of dye in the stream at the injection site depends on the flow rate of the dye solution, the concentration of the dye solution, and the stream discharge. Equations for estimating the gas flow rates, the quantities of the gases, the dye concentration, and the quantity of dye together with procedures for determining the variables in these equations are presented. (Woodard-USGS)

  9. Techniques for Equation-of-State Measurements on a Three-Stage Light-Gas Gun

    SciTech Connect

    REINHART,WILLIAM D.; CHHABILDAS,LALIT C.; THORNHILL,T.G.

    2000-09-14

    Understanding high pressure behavior materials is necessary in order to address the physical processes associated with hypervelocity impact events related to space science applications including orbital debris impact and impact lethality. Until recently the highest-pressure states in materials have been achieved from impact loading techniques from two-stage light gas guns with velocity limitations of approximately 81cm/s. In this paper, techniques that are being developed and implemented to obtain the needed shock loading parameters (Hugoniot states) for material characterization studies, namely shock velocity and particle velocity, will be described at impact velocities up to 11 kds. The determination of equation-of-state (EOS) and thermodynamic states of materials in the regimes of extreme high pressures is now attainable utilizing the three-stage launcher. What is new in this report is that these techniques are being implemented for use at engagement velocities never before attained utilizing two-stage light-gas gun technology. The design and test methodologies used to determine Hugoniot states are described in this paper.

  10. Reconnaissance techniques for determining soil-gas radon concentrations: an example from Prince Georges County, Maryland

    USGS Publications Warehouse

    Reimer, G.M.

    1990-01-01

    Radon reconnaissance requires some special considerations because a large area must be covered in a short period of time and analyses must be made soon after collection because of Rn decay. A simple approach to collection and field analysis consists of a small-diameter probe pounded into the ground to a depth of at least 0.75 m. Analysis is by an alpha-scintillometer. Soil-gas samples collected along a traverse in Prince Georges County, Maryland, demonstrates the utility of the technique. The reconnaissance sampling revealed Rn soil-gas concentrations of up to 2500 pCi/L (picocuries per liter) indicating that the potential exists for indoor accumulations in excess of 4 pCi/L. -from Author

  11. A critical review on extraction techniques and gas chromatography based determination of grapevine derived sesquiterpenes.

    PubMed

    Petronilho, Sílvia; Coimbra, Manuel A; Rocha, Sílvia M

    2014-10-10

    Vitis vinifera L. (common grapevine) is considered one of the major world fruit crops based on the extent of cultivated land and on its economic value. Grapevine is composed by several different chemical compounds, including sesquiterpenic ones. Sesquiterpenic compounds play a significant role in varietal aromas, contributing to fruity and flowery odours, and are also well known for their potential health benefits. The advantages and drawbacks of different extraction and gas chromatographic techniques used for the determination of sesquiterpenic compounds are critically presented. Also, the future trends of sample preparation and gas chromatographic tools are discussed. This review provides the state-of-the-art and the technical know-how for the researchers who want to start studying sesquiterpenic compounds on complex matrices such as grapevine products.

  12. Clipping of TE-CO2 laser pulse using gas breakdown technique for high spatial resolution gas plume detection

    NASA Astrophysics Data System (ADS)

    Gasmi, Taieb

    2014-06-01

    High stability and energy-efficient TE-CO2 laser pulse clipper using gas breakdown techniques for high spatial resolution chemical plume detection is presented. The most dominant time constant, attributed to TE-CO2 unclipped laser pulses, is its nitrogen tail which extends for several microseconds beyond the gain-switched spike. Near-field scattered signal, produced by unclipped laser pulses, interferes with the weak signal backscattered from the long range and far field atmospheric aerosols which ultimately degrades the range resolution of LIDARS to some hundreds of meters. Short laser pulses can be obtained by various techniques such as mode locking, free induction decay, pulse slicing with electro-optic switched. However, output pulses from these require further amplification for any useful application due to their very low energy content. This problem is circumvented in this work by the use of a plasma clipper that achieves high range-resolved remote sensing in the atmosphere. Complete extinction of the nitrogen tail is obtained at pressures extending from 375 up to 1500 Torr for nitrogen and argon gases and approximately 105, for helium. Optimum pressures for helium, argon, and nitrogen, that provide the best stability of the transmitted energy and complete extinction of the nitrogen tail, are identified. Excellent range resolutions can be achieved with TE-CO2 laser-based LIDAR systems. Clipped laser pulses are also field tested.

  13. Investigation of a novel passivation technique for gas atomized magnesium powders

    NASA Astrophysics Data System (ADS)

    Steinmetz, Andrew Douglas

    Gas atomized magnesium powders are critical for the production of a wide variety of flares, tracer projectiles, and other munitions for the United States military, along with a growing number of applications in both alloying and powder metallurgy. Gas atomization of magnesium is performed by numerous companies worldwide, but represents a single point failure within the United States as there is only one domestic producer. These powders are pyrophoric and must be handled carefully and kept dry at all times. Recent studies have explored the ability of certain fluorine containing cover gases to protect molten magnesium in casting operations from excessive vaporization and burning by modifying the native oxide (MgO) through interaction with these gas atmospheres. The present study sought to adapt this melt protection strategy for use as an in-situ passivation technique that could be employed to form a protective reaction film during gas atomization of magnesium powders. This fluorinated oxide shell was intended to provide superior coverage and adherence to the underlying metal, which may improve the ability of powders to resist ignition at elevated temperatures and during powder handling. Two candidate gases were tested in this research, SF6 and NF3, and reaction films of both were produced on miniature melt samples in a controlled environment and characterized using auger electron spectroscopy and x-ray photoelectron spectroscopy. Ultimately, SF6 was chosen to conduct a small scale magnesium atomization experiment for verification of the fluorination reaction and to experimentally test the ignition temperature of these coated particles compared to other magnesium powders available today. This novel passivation technique was found to be far superior to magnesium's native oxide at resisting ignition and, thus, to reduce the hazard associated with handling and transport of magnesium powders for defense applications. If fully commercialized, this passivation method also

  14. Calibration of an optical condensate measurement technique using indirect static headspace gas chromatography.

    PubMed

    Hoke, P B; Loconto, P R; McGrath, J J

    2001-12-01

    Researchers in the Department of Mechanical Engineering seek to obtain a means to measure less than 3 mg of H2O that adheres to a metal surface as condensate. The objective is to calibrate optical reflectance measurements of an aluminum surface as a function of the condensate thickness present. Collaboration with the Hazardous Substance Research Center at Michigan State University results in the development of an indirect static headspace gas chromatographic technique capable of measuring H2O in low-milligram quantities. The technique utilizes manual headspace sampling, a megabore capillary column, and a flame ionization detector. A correlation of r2 = 0.999 is obtained for the calibration of the indirect measurement technique. The calibration of the analytical instrument demonstrates adequate precision (< +/- 50 microg at a 95% confidence interval) for such a heterogeneous sample. The calibration samples consist of a strip of aluminum metal, H2O, and pulverized calcium carbide to convert the H2O to acetylene. A scaled calibration technique is used to simplify handling trace water volumes. The surface reflectance measurements are found to correlate well (r2 = 0.935) with measurements of the condensate mass. This result facilitates the development of an optical mass-transfer measurement technique. This study focuses on the analytical method and its relationship with engineering research.

  15. [Effect of metoclopramide on gastric distension and lethal toxicity of cisplatin in mice].

    PubMed

    Lee, K E; Kubota, T; Sawamura, M; Kadowaki, K

    1986-05-01

    Mice treated with cisplatin (cDDP), were found to have considerably bloated stomachs presumably resulting from paralysis of gastric emptying without appetite suppression and emesis. Repeated administration of metoclopramide (MCP) not only reduced gastric distension, but also the number of toxic deaths after 13 mg/kg of cisplatin i.p. The mechanism of action by which MCP increased the resistance of mice to cDDP seemed to be alleviation of systemic dehydration by means of enhanced gastric emptying. PMID:3707151

  16. Evaluation of corrosion testing techniques for selection of corrosion resistant alloys for sour gas service

    SciTech Connect

    Bhavsar, R.B.; Hibner, E.L.

    1996-08-01

    Slow strain rate (SSR) and C-ring stress corrosion cracking (SCC) tests have historically been used to screen alloys for sour gas environments. The relevance of these testing techniques in predicting actual field corrosion behavior was evaluated for age-hardenable nickel base alloy 925 (UNS N09925) and alloy 718 (UNS N07718). While SSR testing provides an acceptable accelerated screening tool for ranking alloys in sour oil field environments, C-ring SCC testing ranks alloys higher in sour environments than SSR testing.

  17. Systematic comparison of static and dynamic headspace sampling techniques for gas chromatography.

    PubMed

    Kremser, Andreas; Jochmann, Maik A; Schmidt, Torsten C

    2016-09-01

    Six automated, headspace-based sample preparation techniques were used to extract volatile analytes from water with the goal of establishing a systematic comparison between commonly available instrumental alternatives. To that end, these six techniques were used in conjunction with the same gas chromatography instrument for analysis of a common set of volatile organic carbon (VOC) analytes. The methods were thereby divided into three classes: static sampling (by syringe or loop), static enrichment (SPME and PAL SPME Arrow), and dynamic enrichment (ITEX and trap sampling). For PAL SPME Arrow, different sorption phase materials were also included in the evaluation. To enable an effective comparison, method detection limits (MDLs), relative standard deviations (RSDs), and extraction yields were determined and are discussed for all techniques. While static sampling techniques exhibited sufficient extraction yields (approx. 10-20 %) to be reliably used down to approx. 100 ng L(-1), enrichment techniques displayed extraction yields of up to 80 %, resulting in MDLs down to the picogram per liter range. RSDs for all techniques were below 27 %. The choice on one of the different instrumental modes of operation (aforementioned classes) was thereby the most influential parameter in terms of extraction yields and MDLs. Individual methods inside each class showed smaller deviations, and the least influences were observed when evaluating different sorption phase materials for the individual enrichment techniques. The option of selecting specialized sorption phase materials may, however, be more important when analyzing analytes with different properties such as high polarity or the capability of specific molecular interactions. Graphical Abstract PAL SPME Arrow during the extraction of volatile analytes from the headspace of an aqueous sample.

  18. Systematic comparison of static and dynamic headspace sampling techniques for gas chromatography.

    PubMed

    Kremser, Andreas; Jochmann, Maik A; Schmidt, Torsten C

    2016-09-01

    Six automated, headspace-based sample preparation techniques were used to extract volatile analytes from water with the goal of establishing a systematic comparison between commonly available instrumental alternatives. To that end, these six techniques were used in conjunction with the same gas chromatography instrument for analysis of a common set of volatile organic carbon (VOC) analytes. The methods were thereby divided into three classes: static sampling (by syringe or loop), static enrichment (SPME and PAL SPME Arrow), and dynamic enrichment (ITEX and trap sampling). For PAL SPME Arrow, different sorption phase materials were also included in the evaluation. To enable an effective comparison, method detection limits (MDLs), relative standard deviations (RSDs), and extraction yields were determined and are discussed for all techniques. While static sampling techniques exhibited sufficient extraction yields (approx. 10-20 %) to be reliably used down to approx. 100 ng L(-1), enrichment techniques displayed extraction yields of up to 80 %, resulting in MDLs down to the picogram per liter range. RSDs for all techniques were below 27 %. The choice on one of the different instrumental modes of operation (aforementioned classes) was thereby the most influential parameter in terms of extraction yields and MDLs. Individual methods inside each class showed smaller deviations, and the least influences were observed when evaluating different sorption phase materials for the individual enrichment techniques. The option of selecting specialized sorption phase materials may, however, be more important when analyzing analytes with different properties such as high polarity or the capability of specific molecular interactions. Graphical Abstract PAL SPME Arrow during the extraction of volatile analytes from the headspace of an aqueous sample. PMID:27526093

  19. Involvement of the dopaminergic system in the central orexin-induced antinociceptive action against colonic distension in conscious rats.

    PubMed

    Okumura, Toshikatsu; Nozu, Tsukasa; Kumei, Shima; Takakusaki, Kaoru; Miyagishi, Saori; Ohhira, Masumi

    2015-09-25

    We have recently demonstrated that orexin acts centrally in the brain to induce antinociceptive action against colonic distension through orexin 1 receptors in conscious rats. Although the dopaminergic system can induce antinociceptive action for somatic pain, the association between changes in the dopaminergic system and visceral pain perception has not been investigated. In the present study, we hypothesized that the dopaminergic system may be involved in visceral nociception, and if so, the dopaminergic system may mediate the orexin-induced visceral antinociception. Visceral sensation was evaluated using the colonic distension-induced abdominal withdrawal reflex (AWR) in conscious rats. Intracisternal injection of D1 (SKF38398) or D2 (quinpirole) dopamine receptor agonist increased the threshold volume of colonic distension-induced AWR in a dose-dependent manner. Pretreatment with either the D1 or D2 dopamine receptor antagonist (SCH23390 or sulpiride, respectively) potently blocked the centrally injected orexin-A-induced antinociceptive action against colonic distension. These results suggest for the first time that dopaminergic signaling via D1 and D2 dopamine receptors in the brain may induce visceral antinociception and that the dopaminergic signaling may be involved in the central orexin-induced antinociceptive action against colonic distension.

  20. Gas temperature measurements using the dual-line detection Rayleigh scattering technique

    NASA Technical Reports Server (NTRS)

    Otugen, M. Volkan; Seasholtz, Richard G.; Annen, Kurt D.

    1992-01-01

    A new laser-induced Rayleigh scattering method is presented for the improved temperature diagnostics of gas flows. In the present technique, the two lines of a copper vapor laser are used to obtain the time and space resolved temperature. A single set of optics is used to form the optical probe and to collect the signal simultaneously from both the 510 nm and the 578 nm lines. The dual-line detection allows for the determination and removal of surface-scattered laser light from a Rayleigh signal thereby improving the applicability of Rayleigh scattering to near wall flows with a high degree of glare. An optical system using the dual-line detection technique is built, calibrated and tested in a hot air jet under various levels of background contamination. The results indicate that highly accurate temperature measurements are possible even when the laser-line background intensity, captured by the collecting optics, is five times that of the Rayleigh signal.

  1. Recent Developments in Monitoring of Gas and Ash in Volcanic Plumes by Remote Sensing Techniques

    NASA Astrophysics Data System (ADS)

    Arellano, S. R.

    2007-05-01

    Since the 1970s, a growing list of methods for the remote detection and measurement of the composition and dynamics of volcanic plumes has been available for volcanologists and atmospheric scientists. During the last decade of intensive volcanic activity in Ecuador, the use of spectroscopic techniques like COSPEC, DOAS or FTIR has become an important tool in routine volcano monitoring which has resulted in a better understanding of source and path processes related to volcanogenic gas and ash emissions with increasing spatial-temporal resolution capabilities. The most important developments achieved with these techniques include the incorporation of radiative transfer and diffusion modelling in automatic data processing routines. In addition, work is being done to identify and quantitatively estimate the presence of ash by means of UV spectroscopy. The use of these methods allowed us to follow the degassing process of Tungurahua volcano with unprecedented detail. A brief description of these improvements and their results are presented.

  2. New alnico magnets fabricated from pre-alloyed gas-atomized powder through diverse consolidation techniques

    SciTech Connect

    Tang, W.; Zhou, L.; Kassen, A. G.; Palasyuk, A.; White, E. M.; Dennis, K. W.; Kramer, M. J.; McCallum, R. W.; Anderson, I. E.

    2015-05-25

    Fine Alnico 8 spherical powder produced by gas atomization was consolidated through hot pressing (HP), hot isostatic pressing (HIP), and compression molding and subsequent sintering (CMS) techniques. The effects of different fabrication techniques and processing parameters on microstructure and magnetic properties were analyzed and compared. The HP, HIP, and CMS magnets exhibited different features in microstructures and magnetic properties. Magnetically annealed at 840°C for 10 min and subsequently tempered at 650°C for 5h and 580°C for 15h, the HIP sample achieved the best coercivity (Hcj =1845 Oe) due to spinodally decomposed (SD) phases with uniform and well-faceted mosaic morphology. As a result, the CMS sample had a lower Hcj than HIP and HP samples, but a higher remanence and thus the best energy product (6.5 MGOe) due to preferential grain alignment induced by abnormal grain growth.

  3. New alnico magnets fabricated from pre-alloyed gas-atomized powder through diverse consolidation techniques

    DOE PAGES

    Tang, W.; Zhou, L.; Kassen, A. G.; Palasyuk, A.; White, E. M.; Dennis, K. W.; Kramer, M. J.; McCallum, R. W.; Anderson, I. E.

    2015-05-25

    Fine Alnico 8 spherical powder produced by gas atomization was consolidated through hot pressing (HP), hot isostatic pressing (HIP), and compression molding and subsequent sintering (CMS) techniques. The effects of different fabrication techniques and processing parameters on microstructure and magnetic properties were analyzed and compared. The HP, HIP, and CMS magnets exhibited different features in microstructures and magnetic properties. Magnetically annealed at 840°C for 10 min and subsequently tempered at 650°C for 5h and 580°C for 15h, the HIP sample achieved the best coercivity (Hcj =1845 Oe) due to spinodally decomposed (SD) phases with uniform and well-faceted mosaic morphology. Asmore » a result, the CMS sample had a lower Hcj than HIP and HP samples, but a higher remanence and thus the best energy product (6.5 MGOe) due to preferential grain alignment induced by abnormal grain growth.« less

  4. Studying gas-sheared liquid film in horizontal rectangular duct with laser-induced fluorescence technique

    NASA Astrophysics Data System (ADS)

    Cherdantsev, Andrey; Hann, David; Azzopardi, Barry

    2013-11-01

    High-speed LIF-technique is applied to study gas-sheared liquid film in horizontal rectangular duct with 161 mm width. Instantaneous distributions of film thickness resolved in both longitudinal and transverse coordinates were obtained with a frequency of 10 kHz and spatial resolution from 0.125 mm to 0.04 mm. Processes of generation of fast and slow ripples by disturbance waves are the same as described in literature for downwards annular pipe flow. Disturbance waves are often localized by transverse coordinate and may have curved or slanted fronts. Fast ripples, covering disturbance waves, are typically horseshoe-shaped and placed in staggered order. Their characteristic transverse size is of order 1 cm and it decreases with gas velocity. Entrainment of liquid from film surface can also be visualized. Mechanisms of ripple disruption, known as ``bag break-up'' and ``ligament break-up,'' were observed. Both mechanisms may occur on the same disturbance waves. Various scenarios of droplet deposition on the liquid film are observed, including the impact, slow sinking and bouncing, characterized by different outcome of secondary droplets or entrapped bubbles. Number and size of bubbles increase greatly inside the disturbance waves. Both quantities increase with gas and liquid flow rates. EPSRC Programme Grant MEMPHIS (EP/K003976/1), and Roll-Royce UTC (Nottingham, for access to flow facility).

  5. Understanding Methane Emission from Natural Gas Activities Using Inverse Modeling Techniques

    NASA Astrophysics Data System (ADS)

    Abdioskouei, M.; Carmichael, G. R.

    2015-12-01

    Natural gas (NG) has been promoted as a bridge fuel that can smooth the transition from fossil fuels to zero carbon energy sources by having lower carbon dioxide emission and lower global warming impacts in comparison to other fossil fuels. However, the uncertainty around the estimations of methane emissions from NG systems can lead to underestimation of climate and environmental impacts of using NG as a replacement for coal. Accurate estimates of methane emissions from NG operations is crucial for evaluation of environmental impacts of NG extraction and at larger scale, adoption of NG as transitional fuel. However there is a great inconsistency within the current estimates. Forward simulation of methane from oil and gas operation sites for the US is carried out based on NEI-2011 using the WRF-Chem model. Simulated values are compared against measurements of observations from different platforms such as airborne (FRAPPÉ field campaign) and ground-based measurements (NOAA Earth System Research Laboratory). A novel inverse modeling technique is used in this work to improve the model fit to the observation values and to constrain methane emission from oil and gas extraction sites.

  6. The effect of age on the distensibility of the abdominal aorta of man.

    PubMed

    Newman, D L; Lallemand, R C

    1978-08-01

    The variation with age in distensibility and the dimensions of the abdominal aorta at the bifurcation have been measured in 43 fresh human cadavers. The age range was from birth to 69 years, both sexes being represented. Patients with vascular disease were excluded. Barium sulfate infused into the aorta through an iliac artery enabled the change in diameter to be measured from a roentgenogram with change in pressure. Incremental strain value could thus be calculated. Strain value increased from 0.02 at birth to a maximum at the end of the first decade of life and then decreased to less than 0.01 by the age of 70 years. Aortas in the age group of four to 11 years showed less stiffness with increasing pressure than at other ages. Variations of strain with age correlate with alterations in the ratio of aortic wall collagen to elastin in the young. An increase in the thickness of the wall and an atheroma, in response to prolonged hemodynamic stress, account for increased stiffness in the older age groups. Other age and disease factors may play a part, but further work is required in man to examine the role of relative wall thickness, elastic modulus and alteration in wall structure in determining the variation of aortic distensibility with age reported herein.

  7. [Ovarian tumour in a girl with chronic abdominal pain and distension].

    PubMed

    Loeffen, J L C M; Wijnen, M; Schijf, C P T; van Wieringen, P

    2006-03-25

    A 12-year-old girl presented with chronic abdominal pain and distension that had persisted for 6 and 3 months, respectively. The cause was a Sertoli-Leydig cell tumour originating in the left ovary. The cyst and ovary were resected. The patient recovered and was asymptomatic 2 years after the operation. Ovarian tumours are rarely seen in children. The sex cordstromal tumours constitute a heterogeneous subgroup. Two of the most frequently observed sex cord-stromal tumours are the juvenile granulosa cell tumour and the Sertoli-Leydig cell tumour. Even though these tumours may contain histologically malignant characteristics, their behaviour is usually benign. Clinical characteristics are endocrine symptoms, fatigue, chronic abdominal pain and abdominal distension. In addition, pressure from the tumour mass may result in symptoms in adjacent organ systems. Surgical excision is usually curative. Patients with advanced disease may benefit from adjuvant chemotherapy. Chronic abdominal pain is frequently observed in children and, in some rare cases, may be caused by ovarian tumours.

  8. Decreased carotid artery distensibility as a sign of early atherosclerosis in viscose rayon workers.

    PubMed

    Kotseva, K; Braeckman, L; Duprez, D; De Bacquer, D; De Buyzere, M; Van De Veire, N; Vanhoorne, M

    2001-06-01

    Carbon disulphide (CS(2)) is known to accelerate atherosclerosis and to increase the risk for cardiovascular diseases. To assess the effect of CS(2) on the functional (distensibility and compliance) and the structural (intima media thickness) properties of the common carotid artery, and blood pressure and lipid metabolism parameters, a cross-sectional study on 85 workers from a viscose rayon factory and 37 controls was carried out. Exposure to CS(2) was assessed by personal monitoring and was well below the threshold limit value-time weighted average. Carotid arterial wall properties were determined using a non-invasive ultrasound wall movement detector system. No significant effect of CS(2) on blood pressure, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol or triglycerides was found. Among the vascular parameters studied, only distensibility was significantly lower and heart rate was significantly higher in exposed subjects compared with the controls. In conclusion, occupational exposure to CS(2) may cause early alterations in arterial elastic properties in young individuals, and even before lipid and clinical findings have occurred, important functional changes in the vessel wall are present.

  9. From comic relief to real understanding; how intestinal gas causes symptoms.

    PubMed

    Quigley, E M M

    2003-12-01

    Gas content and transit appear to conspire with the motor and sensory responses of the gut to produce gas related symptoms, both in normal individuals and especially in patients with irritable bowel syndrome (IBS). In relation to gas in IBS, two questions need to be addressed: do IBS patients produce more gas and what are the relationships between intestinal gas and symptoms? The balance of evidence seems to indicate that distension is a real phenomenon in IBS and that such distension accurately reflects gas content. More problematic is extrapolation of the observations relating symptoms to gas transit and retention.

  10. Combined FTIR-micrometeorological techniques for long term measurements of greenhouse gas fluxes from agriculture

    NASA Astrophysics Data System (ADS)

    Petersen, A. K.; Griffith, D.; Harvey, M.; Naylor, T.; Smith, M.

    2009-04-01

    The exchange of trace gases between the biosphere and the atmosphere affects the atmospheric concentrations of gases such as methane, carbon dioxide, nitrous oxide, carbon monoxide, ammonia, volatile organic compounds, nitrogen dioxide and others. The quantification of the exchange between a biogenic system and the atmosphere is necessary for the evaluation of the impact of these interactions. This is of special interest for agricultural systems which can be sources or sinks of trace gases, and the measurement of the fluxes is necessary when evaluating both the environmental impact of agricultural activities and the impact of atmospheric pollution on agricultural production and sustainability. With the exception of CO2, micrometeorological measurements of the fluxes of greenhouse gases from agricultural activities are still mostly possible only in campaign mode due to the complexity and logistical requirements of the existing measurement techniques. This limitation precludes studies of fluxes which run for longer periods, for example over full seasonal or growing cycles for both animal- and crop-based agriculture. We have developed an instrument system for long-term flux measurements through a combination of micrometeorological flux measurement techniques such as Relaxed Eddy Accumulation (REA) and Flux-Gradient (FG) with the high precision multi-species detection capabilities of FTIR spectroscopy. The combined technique is capable of simultaneous flux measurements of N2O, CH4 and CO2 at paddock to regional scales continuously, over longer terms (months, seasonal cycles, years). The system was tested on a 3 weeks field campaign in NSW, Australia on a flat, homogeneous circular grass paddock with grazing cattle. The flux of the atmospheric trace gas CO2 was measured with three different micrometeorological techniques: Relaxed Eddy Accumulation, Flux-Gradient, and Eddy Correlation. Simultaneously, fluxes of CH4 and N2O were measured by REA and FG technique.

  11. Comparison of microbial and sorbed soil gas surgace geochemical techniques with seismic surveys from the Southern Altiplano, Bolivia

    SciTech Connect

    Aranibar, O.R.; Tucker, J.D.; Hiltzman, D.C.

    1995-12-31

    Yacimientos Petroliferos Fiscales Bolivianos (YPFB) undertook a large seismic evaluation in the southern Altiplano, Bolivia in 1994. As an additional layer of information, sorbed soil gas and Microbial Oil Survey Technique (MOST) geochemical surveys were conducted to evaluate the hydrocarbon microseepage potential. The Wara Sara Prospect had 387 sorbed soil gas samples, collected from one meter depth, and 539 shallow soil microbial samples, collected from 15 to 20 centimeter depth. The sorbed soil gas samples were collected every 500 meters and microbial samples every 250 meters along geochemical traverses spaced 1 km apart. The presence of anmalous hydrocarbon microseepage is indicated by (1) a single hydrocarbon source identified by gas crossplots, (2) the high gas values with a broad range, (3) the high overall gas average, (4) the clusters of elevated samples, and (5) the right hand skewed data distributions.

  12. Identification of capsaicin-sensitive rectal mechanoreceptors activated by rectal distension in mice.

    PubMed

    Spencer, N J; Kerrin, A; Singer, C A; Hennig, G W; Gerthoffer, W T; McDonnell, O

    2008-05-01

    Rodents detect visceral pain in response to noxious levels of rectal distension. However, the mechanoreceptors that innervate the rectum and respond to noxious levels of rectal distension have not been identified. Here, we have identified the mechanoreceptors of capsaicin-sensitive rectal afferents and characterized their properties in response to circumferential stretch of the rectal wall. We have also used the lethal spotted (ls/ls) mouse to determine whether rectal mechanoreceptors that respond to capsaicin and stretch may also develop in an aganglionic rectum that is congenitally devoid of enteric ganglia. In wild type (C57BL/6) mice, graded increases in circumferential stretch applied to isolated rectal segments activated a graded increase in firing of slowly-adapting rectal mechanoreceptors. Identical stimuli applied to the aganglionic rectum of ls/ls mice also activated similar graded increases in firing of stretch-sensitive rectal afferents. In both wild type and aganglionic rectal preparations, focal compression of the serosal surface using von Frey hairs identified mechanosensitive "hot spots," that were associated with brief bursts of action potentials. Spritzing capsaicin (10 microM) selectively onto each identified mechanosensitive hot spot activated an all or none discharge of action potentials in 32 of 56 identified hot spots in wild type mice and 24 of 62 mechanosensitive hot spots in the aganglionic rectum of ls/ls mice. Each single unit activated by both capsaicin and circumferential stretch responded to low mechanical thresholds (1-2 g stretch). No high threshold rectal afferents were ever recorded in response to circumferential stretch. Anterograde labeling from recorded rectal afferents revealed two populations of capsaicin-sensitive mechanoreceptor that responded to stretch: one population terminated within myenteric ganglia, the other within the circular and longitudinal smooth muscle layers. In the aganglionic rectum of ls/ls mice, only the

  13. Field comparison of disjunct and conventional eddy covariance techniques for trace gas flux measurements.

    PubMed

    Rinne, J; Douffet, T; Prigent, Y; Durand, P

    2008-04-01

    A field intercomparison experiment of the disjunct eddy covariance (DEC) and the conventional eddy covariance (EC) techniques was conducted over a grass field. The half-hourly water vapor fluxes measured by the DEC were within the estimated uncertainty from the fluxes measured by the EC. On the average there was a slight overestimation (<10%) of the fluxes measured by the DEC during the day and underestimation during the night as compared to the fluxes measured by the EC. As this bias does not appear in the simulated DEC measurements it is likely to be due to instrumental problems. The insensitivity of the quality of the fluxes measured by the DEC method to the deficiencies in the gas analysis shows the robustness of this new approach for measuring the surface-atmosphere exchange of trace gases.

  14. Differential correction technique for removing common errors in gas filter radiometer measurements.

    PubMed

    Wallio, H A; Chan, C C; Gormsen, B B; Reichle, H G

    1992-12-20

    The Measurement of Air Pollution from Satellites (MAPS) gas filter radiometer experiment was designed to measure CO mixing ratios in the Earth's atmosphere. MAPS also measures N(2)O to provide a reference channel for the atmospheric emitting temperature and to detect the presence of clouds. In this paper we formulate equations to correct the radiometric signals based on the spatial and temporal uniformity of the N(2)O mixing ratio in the atmosphere. Results of an error study demonstrate that these equations reduce the error in inferred CO mixing ratios. Subsequent application of the technique to the MAPS 1984 data set decreases the error in the frequency distribution of mixing ratios and increases the number of usable data points.

  15. Application of a new multiple fracturing technique to enhance gas production in Devonian shale

    SciTech Connect

    Cuderman, J.F.

    1984-01-01

    A new multiple fracturing technology has been applied in stimulating a Devonian shale gas well. In this new technique, propellants are used to obtain controlled pressurization of the wellbore to produce multiple fractures. The pressurization is controlled by suitable choice of propellants having different burn rates. The pressure risetime is the most important parameter governing fracture behavior. Methods are presented for specifying both the risetime and propellants to achieve it for Devonian shales. The Devonian shale stimulation was conducted in a 1040 m deep well in Meigs Co., Ohio. The experimental installation and hardware used are described together with results which include an increase in production from 190 m/sup 3//day to 623 m/sup 3//day. 7 references, 5 figures, 1 table.

  16. Simulation Based on Negative ion pair Techniques of Electric propulsion In Satellite Mission Using Chlorine Gas

    NASA Astrophysics Data System (ADS)

    Bakkiyaraj, R.

    R.Bakkiyaraj,Assistant professor,Government college of Engineering ,Bargur,Tamilnadu. *C.Sathiyavel, PG Student and Department of Aeronautical Engineering/Branch of Avionics, PSN college of Engineering and Technology,Tirunelveli,India. Abstract: Ion propulsion rocket system is expected to become popular with the development of ion-ion pair techniques because of their stimulated of low propellant, Design of repulsive between negative ions with low electric power and high efficiency. A Negative ion pair of ion propulsion rocket system is proposed in this work .Negative Ion Based Rocket system consists of three parts 1.ionization chamber 2. Repulsion force and ion accelerator 3. Exhaust of Nozzle. The Negative ions from electro negatively gas are produced by attachment of the gas ,such as chlorine with electron emitted from a Electron gun ionization chamber. The formulate of large stable negative ion is achievable in chlorine gas with respect to electron affinity (∆E). When a neutral chlorine atom in the gaseous form picks up an electron to form a cl- ion, it releases energy of 349 kJ/mol or 3.6 eV/atom. It is said to have an electron affinity of -349 kJ/mol ,the negative sign indicating that energy is released during this process .The distance between negative ions pair is important for the evaluation of the rocket thrust and is also determined by the exhaust velocity of the propellant. The mass flow rate of ions is related to the ion beam current. Accelerate the Negative ions to a high velocity in the thrust vector direction with a significantly intense grids and the exhaust of negative ions through Nozzle. The simulation of the ion propulsion system has been carried out by MATLAB. By comparing the simulation results with the theoretical and previous results, we have found that the proposed method is achieved of thrust value with low electric power for simulating the ion propulsion rocket system

  17. Technique for harvesting unicellular algae using colloidal gas aphrons. [Chlorella vulgaris

    SciTech Connect

    Honeycutt, S.S.; Wallis, D.A.; Sebba, F.

    1983-01-01

    A novel technique using colloidal gas aphron (CGA) dispersions has been investigated for harvesting Chlorella vulgaris, a unicellular green algae, from dilute suspension. CGA are very small gas bubbles, on the order of 25 ..mu..m in diameter, that are each encapsulated in an aqueous shell of surfactant solution. The process is based on the technology of CGA flotation, which involves the formation of algae-bubble complexes and their subsequent flotation to the surface. At neutral pH, the efficiency of algae removal was maximized when a cationic surfactant (lauryl pyridinium chloride) was used for CGA generation. At pH 10, both the cationic and anionic (sodium dodecyl benzene sulfonate) CGA dispersions yielded comparable removals. Addition of small quantities of alum (to 10/sup -4/M) improved removals using the cationic CGA, and at pH 10 this combination yielded the maximum removals that were achieved: 52.1% removal after a single application of CGA dispersion (1 to 1, dispersion to sample volume ratio), and 89.2% removal after an additional application. 12 references, 1 figure, 2 tables.

  18. Development of a technique for mercury speciation and quantification using gas chromatography/mass spectrometry

    SciTech Connect

    Barshick, S.A.; Barshick, C.M.; Britt, P.F.; Vance, M.A.; Duckworth, D.C.

    1997-07-01

    One element of concern to DOE is mercury. Mercury was used extensively at the DOE facilities in Oak Ridge, Tennessee from 1950 to 1963 in the process of making lithium deuteride, a component of nuclear weapons. Although both the inorganic and organometallic forms of mercury are toxic to humans, the organic compounds are often more toxic. Since the toxicity of mercury is a function of its chemical form, an understanding of the interactions between commercially discharged mercury, naturally occurring mercury, and the environment in which they are present is vital. In this report, the authors have been investigating gas chromatography/mass spectrometry (GC/MS) for the analysis of both the organometallic and inorganic forms of mercury in the same environmental sample (e.g., solutions, soils, and sludges). Although gas chromatography is the classical technique for analyzing organic molecules, (e.g., organometallic compounds) little has been done on the analysis of inorganic compounds. In a previous publication, the authors described how a solid phase microextraction (SPME) fiber could be used to sample organomercurials from aqueous samples. An alkylation reaction was then carried out to transform chemically mercury nitrate into dimethylmercury; subsequent GC/MS analysis of this compound permitted quantification of the inorganic constituent. Subsequently, several different alkylation reagents have been synthesized that methylate any inorganic mercury compound to methylmercury iodide. Here, the authors report results on alkylation reaction time and the effect of pH on the population of the product.

  19. Initial velocity of secondary ions from XY-TOF technique, simultaneous calibration by residual gas ionization

    NASA Astrophysics Data System (ADS)

    Jalowy, T.; Weber, Th; Dörner, R.; Farenzena, L.; Collado, V. M.; da Silveira, E. F.; Schmidt-Böcking, H.; Groeneveld, K. O.

    2004-01-01

    A crucial parameter to distinguish the prompt secondary ion emission from surfaces after particle impact from the delayed one is T0(m/q), the time-of-flight (TOF) of ions with a given mass m and charge q "emitted" with zero velocity. This quantity is also an important reference for the measurement of prompt ion emission velocity distribution. Presented is a novel and accurate method to determine T0(m/q), based on position sensitive XY-TOF analysis of residual gas ionization along the projectile trajectory, which is a low-pressure version of the traditional cloud chamber technique. Measurements using a mixture of He, Ne and Ar gases at low pressure (10-5 mbar) were performed to illustrate this new T0-gas target calibration method. Secondary ion emission of Hn+, CnHn+ and Li+ ions from C, Al and LiF targets, bombarded by MeV Ar0 and N0 projectiles, is analyzed. It is found that, in contrast to Li+, hydrogen and hydrocarbon ions are always promptly emitted. The initial velocity distribution of H2+ is determined and discussed.

  20. Nitric Oxide Synthase Promotes Distension-Induced Tracheal Venular Leukocyte Adherence

    PubMed Central

    Moldobaeva, Aigul; Rentsendorj, Otgonchimeg; Jenkins, John; Wagner, Elizabeth M.

    2014-01-01

    The process of leukocyte recruitment to the airways in real time has not been extensively studied, yet airway inflammation persists as a major contributor to lung pathology. We showed previously in vivo, that neutrophils are recruited acutely to the large airways after periods of airway distension imposed by the application of positive end-expiratory pressure (PEEP). Given extensive literature implicating products of nitric oxide synthase (NOS) in lung injury after ventilatory over-distension, we questioned whether similar mechanisms exist in airway post-capillary venules. Yet, endothelial nitric oxide has been shown to be largely anti-inflammatory in other systemic venules. Using intravital microscopy to visualize post-capillary tracheal venules in anesthetized, ventilated mice, the number of adherent leukocytes was significantly decreased in eNOS-/- mice under baseline conditions (2±1 cell/60 min observation) vs wild type (WT) C57BL/6 mice (7±2 cells). After exposure to PEEP (8 cmH2O for 1 min; 5 times), adherent cells increased significantly (29±5 cells) in WT mice while eNOS-/- mice demonstrated a significantly decreased number of adherent cells (11±4 cells) after PEEP. A similar response was seen when thrombin was used as the pro-inflammatory stimulus. In addition, mouse tracheal venular endothelial cells studied in vitro after exposure to cyclic stretch (18% elongation) or thrombin both demonstrated increased p-selectin expression that was significantly attenuated by NG-nitro-L-arginine methyl ester, N-acetylcysteine amide (NACA) and excess BH4. In vivo treatment with the ROS inhibitor NACA or co-factor BH4 abolished completely the PEEP-induced leukocyte adherence. These results suggest that pro-inflammatory stimuli cause leukocyte recruitment to tracheal endothelium in part due to eNOS uncoupling. PMID:25181540

  1. Alternative Techniques for Injecting Massive Quantities of Gas for Plasma Disruption Mitigation

    SciTech Connect

    Combs, Stephen Kirk; Meitner, Steven J; Caughman, John B; Commaux, Nicolas JC; Fehling, Dan T; Foust, Charles R; Jernigan, Thomas C; McGill, James M; Parks, P. B.; Rasmussen, David A

    2010-01-01

    Injection of massive quantities of noble gases or D2 has proven to be effective at mitigating some of the deleterious effects of disruptions in tokamaks. Two alternative methods that might offer some advantages over the present technique for massive gas injection are shattering massive pellets and employing closecoupled rupture disks. Laboratory testing has been carried out to evaluate their feasibility. For the study of massive pellets, a pipe gun pellet injector cooled with a cryogenic refrigerator was fitted with a relatively large barrel (16.5 mm bore), and D2 and Ne pellets were made and were accelerated to speeds of ~600 and 300 m/s, respectively. Based on the successful proof-of-principle testing with the injector and a special double-impact target to shatter pellets, a similar system has been prepared and installed on DIII-D, with preliminary experiments already carried out. To study the applicability of rupture disks for disruption mitigation, a simple test apparatus was assembled in the lab. Commercially available rupture disks of 1 in. nominal diameter were tested at conditions relevant for the application on tokamaks, including tests with Ar and He gases and rupture pressures of ~54 bar. Some technical and practical issues of implementing this technique on a tokamak are discussed.

  2. Monitoring the convergence and the stability of high-pressure gas storage cavities by echometric techniques

    SciTech Connect

    Denzau, H.; Erhardt, S.; Wierczeyco, E.

    1988-01-01

    To demonstrate the stability of high-pressure gas storage cavities and to monitor cavity convergence, a fully computerized echometric sonar technique was developed in the early eighties. Cavity surveys made by this technique at regular intervals in accordance with requirements imposed by mining authorities are necessary to monitor the stability of cavities as well as to predict cavity life and the effect of cavity convergence on the surface. Unlike conventional methods determining overall cavity closure, the new echometric sonar method allows the calculation of convergence as a function of depth by an intercomparison of data from different surveys. The first operation in the interpretation process is a numerical comparison of the data of vertical and horizontal cross-sections of two successive surveys. This operation will identify changes in the shape of a cavity which may occur if the cavity is leached in a steep-sloped salt dome. Following a verification of the computerized interpretation of the data, the volume of fall is calculated and cross-checked against the volume of rock deposited on the bottom of the cavity.

  3. Gas-liquid chromatographic headspace technique for determination of vinyl chloride in corn oil and three food-simulating solvents.

    PubMed

    Diachenko, G W; Breder, C V; Brown, M E; Dennison, J L

    1977-05-01

    A gas-liquid chromatographic headspace technique for the determination of vinyl chloride (VC) in corn oil, 50% ethanol, 3% acetic acid, and n-heptane is described. These food-simulating solvents and the corn oil are placed in septum-sealed bottles and heated to 90 degrees C, and aliquots of headspace vapor are injected into a gas-liquid chromatograph equipped with a flame ionization detector. VC may be quantitated at concentrations of 1 ppb or less. This technique was used to measure the migration of VC into corn oil and 50% ethanol from 2 unplasticized polyvinyl chloride sheets containing 0.28 and 0.44 ppm residual monomer.

  4. Application of plasma gas modulation technique for improvement of the measurement of Mn emission intensity in ICP-AES.

    PubMed

    Kubota, K; Wagatsuma, K

    2001-01-01

    A phase-sensitive detection technique associated with a digital lock-in amplifier was applied for an improvement of the detection in ICP-AES. The lock-in amplifier works as an extremely narrow band pass filter. It can pick up the modulated signal, which has the same frequency as the reference signal, from any noise and thus it can improve the signal-to-noise ratio. Modulation of the ICP can be performed by mixing small amounts of air to argon as the outer gas cyclically, because the emission intensities of ionic lines are enhanced by using the mixed gas. An electromagnetic valve, which is placed in the outer-gas flow path, causes periodic variation in the air gas in the outer-gas flow, and thus switching the valve on/off can modulate the ICP. By choosing the appropriate conditions, the addition of air gas enhances the emission intensity of ionic lines more than that of the background, thus leading to improved signal-to-background ratios. At the same time the lock-in amplifier further enhances the ionic emissions because it picks up only the modulated part of the signal. By applying the plasma gas flow modulation technique the detection and the determination limits of the Mn II 257.610 nm line are improved in comparison with the conventional method. A change in plasma shape corresponding to the modulation frequency is observed when the ICP is modulated. PMID:11225355

  5. Wellsite, laboratory, and mathematical techniques for determining sorbed gas content of coals and gas shales utilizing well cuttings

    USGS Publications Warehouse

    Newell, K.D.

    2007-01-01

    Drill cuttings can be used for desorption analyses but with more uncertainty than desorption analyses done with cores. Drill cuttings are not recommended to take the place of core, but in some circumstances, desorption work with cuttings can provide a timely and economic supplement to that of cores. The mixed lithologic nature of drill cuttings is primarily the source of uncertainty in their analysis for gas content, for it is unclear how to apportion the gas generated from both the coal and the dark-colored shale that is mixed in usually with the coal. In the Western Interior Basin Coal Basin in eastern Kansas (Pennsylvanian-age coals), dark-colored shales with normal (??? 100 API units) gamma-ray levels seem to give off minimal amounts of gas on the order of less than five standard cubic feet per ton (scf/ton). In some cuttings analyses this rule of thumb for gas content of the shale is adequate for inferring the gas content of coals, but shales with high-gamma-ray values (>150 API units) may yield several times this amount of gas. The uncertainty in desorption analysis of drill cuttings can be depicted graphically on a diagram identified as a "lithologic component sensitivity analysis diagram." Comparison of cuttings desorption results from nearby wells on this diagram, can sometimes yield an unique solution for the gas content of both a dark shale and coal mixed in a cuttings sample. A mathematical solution, based on equating the dry, ash-free gas-contents of the admixed coal and dark-colored shale, also yields results that are correlative to data from nearby cores. ?? 2007 International Association for Mathematical Geology.

  6. Use of the gas-filled-magnet technique for particle identification at low energies

    SciTech Connect

    Rehm, K.K.; Jiang, C.L.; Paul, M.

    1995-08-01

    Reaction studies of interest to astrophysics with radioactive ion beams will be done mainly in inverse reaction kinematics, i.e., heavy particles bombarding a hydrogen target. The low energy of the outgoing heavy reaction products makes particle identification with respect to mass and nuclear charge a major challenge. For the planned {sup 18}F(p,{alpha}) experiment one expects five different types of particles in the outgoing channels: {sup 18}F and {sup 18}O (from elastic scattering of {sup 18}F and {sup 18}O on {sup 12}C), {sup 15}O and {sup 15}N (from the {sup 18}F and {sup 18}O induced (p,{alpha}) reactions) and {sup 12}C recoils from the polypropylene target. While mass determination can be achieved easily by time-of-flight (TOF) measurements, a determination of the nuclear charge presents a challenge, especially if the energy of the particles is below 500 keV/u. We studied the gas-filled magnet technique for Z-identification of light ions between Z = 6-9. In a gas-filled magnet the particles move with an average charge state {bar q} which in one parameterization is given by {bar q} = Z ln(avZ{sup {alpha}})/ln(bZ{sup {beta}}) where Z is the nuclear charge of the ions and v their velocity. Introducing into the expression for the magnetic rigidity B{rho} = mv/{bar q} results in a Z dependence of B{rho} which is valid to very low velocities. As a magnet we used the Enge split-pole spectrograph which was filled with nitrogen gas at a pressure of 0.5 Torr. The particles were detected in the focal plane with a 50 x 10 cm{sup 2} parallel-grid-avalanche counter which measured TOF and magnetic rigidity. The mass and Z separation was tested with {sup 13}C and {sup 18}O beams at energies of about 600 keV/u and recoil particles ranging from {sup 12}C to {sup 19}F. The Z-separation obtained at these energies was {triangle}Z/Z = 0.28 which is sufficient to separate individual elements for Z < 10.

  7. A survey of tracer gas techniques for estimation airflow and effective volumes in single and multizone buildings

    SciTech Connect

    O'Neill, P.J.

    1990-10-01

    This paper briefly describes the development of tracer gas techniques. These techniques were introduced over 50 years ago and have evolved into a number of distinct methods. These methods are often tailored to a specific application or to obtain particular information about the flow and volume system. Single-zone techniques are utilized when the structure or zone is relatively well-mixed and can be characterized by a single concentration measurement. Areas or rooms within a single-family residence can sometimes be closely approximated as one well-mixed zone. Multizone techniques are required when the building is composed of two or more zones which communicate with one another through interzonal airflows. Commercial office buildings are usually multizone systems. This paper focuses on single and multiple gas tracer techniques. Traditionally, multizone systems have been analyzed by using a different tracer for each zone. These techniques require equipment capable of accurately injecting and detecting each of the tracers which can be cumbersome in large order systems. Recently, a number of methods have been proposed which use a single tracer gas to estimate flow and effective volumes in multizone systems. 24 refs., 2 figs., 1 tab.

  8. Beam-foil-gas spectroscopy - A technique for studying steady-state non-equilibrium processes.

    NASA Technical Reports Server (NTRS)

    Bickel, W. S.; Veje, E.; Carriveau, G.; Anderson, N.

    1971-01-01

    When a thin foil is inserted in the beam of a beam-gas experiment, the beam particle state populations are driven far from their beam-gas equilibrium values. Downstream from the foil, the 'new beam' and gas species interact to produce a new equilibrium, usually different from the beam-gas equilibrium. Experimental results are presented to demonstrate this effect and to show how relative cross-section measurements can be used to study the beam-foil interaction.

  9. Porosity of coal and shale: Insights from gas adsorption and SANS/USANS techniques

    SciTech Connect

    Mastalerz, Maria; He, Lilin; Melnichenko, Yuri B; Rupp, John A

    2012-01-01

    Two Pennsylvanian coal samples (Spr326 and Spr879-IN1) and two Upper Devonian-Mississippian shale samples (MM1 and MM3) from the Illinois Basin were studied with regard to their porosity and pore accessibility. Shale samples are early mature stage as indicated by vitrinite reflectance (R{sub o}) values of 0.55% for MM1 and 0.62% for MM3. The coal samples studied are of comparable maturity to the shale samples, having vitrinite reflectance of 0.52% (Spr326) and 0.62% (Spr879-IN1). Gas (N{sub 2} and CO{sub 2}) adsorption and small-angle and ultrasmall-angle neutron scattering techniques (SANS/USANS) were used to understand differences in the porosity characteristics of the samples. The results demonstrate that there is a major difference in mesopore (2-50 nm) size distribution between the coal and shale samples, while there was a close similarity in micropore (<2 nm) size distribution. Micropore and mesopore volumes correlate with organic matter content in the samples. Accessibility of pores in coal is pore-size specific and can vary significantly between coal samples; also, higher accessibility corresponds to higher adsorption capacity. Accessibility of pores in shale samples is low.

  10. Structural, morphological and gas sensing study of palladium doped tin oxide nanoparticles synthesized via hydrothermal technique

    NASA Astrophysics Data System (ADS)

    Singh, Davender; Kundu, Virender Singh; Maan, A. S.

    2015-11-01

    In this article pure and Pd-doped SnO2 (Pd:SnO2) nanoparticles with various mol% Pd have been synthesized by hydrothermal technique. To characterize the morphology, crystallinity, and structure of the SnO2 and Pd:SnO2 X-ray diffraction (XRD) and scanning electron microscope (SEM) studies were used. XRD analysis reveal that all nanoparticles of different doping concentration are highly polycrystalline in nature. Pd-doped SnO2 crystals existed mainly as tetragonal rutile structure. The particle size of the nanoparticles was calculated by using the Scherrer formula and was found in the range of 8-27 nm. The SEM images of the studied nanoparticles confirms the existence of very small, homogeneously distributed, spherical and extremely crystalline nanoparticles. EDX analysis confirms the presence of palladium. The Fourier transform infrared spectroscopy (FTIR) study confirmed the formation of Sn-O phase and hydrous nature of the pure and Pd-doped SnO2 nanoparticles. The gas sensing response of SnO2 and Pd:SnO2 nanoparticles was studied towards different reducing gases at different operating temperatures. Among all samples under study, 0.20% Pd-doped SnO2 exhibits best response towards different gases. 0.20% Pd-doped SnO2 shows maximum response 88% to ethanol, 80% to CO and 78% to H2 at concentration of 100 ppm respectively at different operating temperature within the measurement limit.

  11. Comparison of velocimetry techniques for turbulent structures in gas-puff imaging data.

    PubMed

    Sierchio, J M; Cziegler, I; Terry, J L; White, A E; Zweben, S J

    2016-02-01

    Recent analysis of Gas Puff Imaging (GPI) data from Alcator C-Mod found blob velocities with a modified tracking time delay estimation (TDE). These results disagree with velocity analysis performed using direct Fourier methods. In this paper, the two analysis methods are compared. The implementations of these methods are explained, and direct comparisons using the same GPI data sets are presented to highlight the discrepancies in measured velocities. In order to understand the discrepancies, we present a code that generates synthetic sequences of images that mimic features of the experimental GPI images, with user-specified input values for structure (blob) size and velocity. This allows quantitative comparison of the TDE and Fourier analysis methods, which reveals their strengths and weaknesses. We found that the methods agree for structures of any size as long as all structures move at the same velocity and disagree when there is significant nonlinear dispersion or when structures appear to move in opposite directions. Direct Fourier methods used to extract poloidal velocities give incorrect results when there is a significant radial velocity component and are subject to the barber pole effect. Tracking TDE techniques give incorrect velocity measurements when there are features moving at significantly different speeds or in different directions within the same field of view. Finally, we discuss the limitations and appropriate use of each of methods and applications to the relationship between blob size and velocity. PMID:26931844

  12. Comparison of velocimetry techniques for turbulent structures in gas-puff imaging data.

    PubMed

    Sierchio, J M; Cziegler, I; Terry, J L; White, A E; Zweben, S J

    2016-02-01

    Recent analysis of Gas Puff Imaging (GPI) data from Alcator C-Mod found blob velocities with a modified tracking time delay estimation (TDE). These results disagree with velocity analysis performed using direct Fourier methods. In this paper, the two analysis methods are compared. The implementations of these methods are explained, and direct comparisons using the same GPI data sets are presented to highlight the discrepancies in measured velocities. In order to understand the discrepancies, we present a code that generates synthetic sequences of images that mimic features of the experimental GPI images, with user-specified input values for structure (blob) size and velocity. This allows quantitative comparison of the TDE and Fourier analysis methods, which reveals their strengths and weaknesses. We found that the methods agree for structures of any size as long as all structures move at the same velocity and disagree when there is significant nonlinear dispersion or when structures appear to move in opposite directions. Direct Fourier methods used to extract poloidal velocities give incorrect results when there is a significant radial velocity component and are subject to the barber pole effect. Tracking TDE techniques give incorrect velocity measurements when there are features moving at significantly different speeds or in different directions within the same field of view. Finally, we discuss the limitations and appropriate use of each of methods and applications to the relationship between blob size and velocity.

  13. [The express mode of identification of agents of bacteriemias using the technique of gas chromatography-mass spectrometry].

    PubMed

    Popov, D A; Ovseyenko, S T; Osipov, G A; Vostrikova, T Yu

    2013-05-01

    The comparative evaluation was carried out concerning the effectiveness of generic identification of hemocultures using the technique of gas chromatography-mass spectrometry by comparison with data of common cultural method. The content of vials with positive hemoculture was analyzed using both the common microbiologic methods and the technique of gas chromatography-mass spectrometry with detection of markers of the most widespread agents of nosocomial bacteriemias: microorganisms of genus Staphylococcus, Enterococcus, Klebsiella, Escherichia, Serratia, Pseudomonas, Acinetobacter, Stenotrophomonas, Candida. The possibility of applying the technique of gas chromatography-mass spectrometry for generic express-identification of agents of bacteriemias was established. The full concurrence of results obtained by gas chromatography-mass spectrometry with the results of common bacteriologic method was revealed. The time saving of analysis during generic identification of hemocultures using gas chromatography-mass spectrometry up to three and less hours against 1.5-2 days in case of common approach. The established information can input into earlier start of etiotropic therapy under severe infections.

  14. Gas-phase thermal dissociation of uranium hexafluoride: Investigation by the technique of laser-powered homogeneous pyrolysis

    SciTech Connect

    Bostick, W.D.; McCulla, W.H.; Trowbridge, L.D.

    1987-04-01

    In the gas-phase, uranium hexafluoride decomposes thermally in a quasi-unimolecular reaction to yield uranium pentafluoride and atomic fluorine. We have investigated this reaction using the relatively new technique of laser-powered homogeneous pyrolysis, in which a megawatt infrared laser is used to generate short pulses of high gas temperatures under strictly homogeneous conditions. In our investigation, SiF/sub 4/ is used as the sensitizer to absorb energy from a pulsed CO/sub 2/ laser and to transfer this energy by collisions with the reactant gas. Ethyl chloride is used as an external standard ''thermometer'' gas to permit estimation of the unimolecular reaction rate constants by a relative rate approach. When UF/sub 6/ is the reactant, CF/sub 3/Cl is used as reagent to trap atomic fluorine reaction product, forming CF/sub 4/ as a stable indicator which is easily detected by infrared spectroscopy. Using these techniques, we estimate the UF/sub 6/ unimolecular reaction rate constant near the high-pressure limit. In the Appendix, we describe a computer program, written for the IBM PC, which predicts unimolecular rate constants based on the Rice-Ramsperger-Kassel theory. Parameterization of the theoretical model is discussed, and recommendations are made for ''appropriate'' input parameters for use in predicting the gas-phase unimolecular reaction rate for UF/sub 6/ as a function of temperature and gas composition and total pressure. 85 refs., 17 figs., 14 tabs.

  15. A new technique to estimate volcanic gas composition: plume measurements with a portable multi-sensor system

    NASA Astrophysics Data System (ADS)

    Shinohara, Hiroshi

    2005-05-01

    A portable multi-sensor system was developed to measure volcanic plumes in order to estimate the chemical composition and temperature of volcanic gases. The multi-sensor system consists of a humidity-temperature sensor, SO 2 electrochemical sensor, CO 2 IR analyzer, pump and flow control units, pressure sensor, data logger, and batteries; the whole system is light (˜5 kg) and small enough to carry in a medium-size backpack. Volcanic plume is a mixture of atmosphere and volcanic gas; therefore volcanic gas composition and temperature can be estimated by subtracting the atmospheric gas background from the plume data. In order to obtain the contrasting data of the plume and the atmosphere, measurements were repeated in and out of the plume. The multi-sensor technique was applied to measure the plume of Tarumae, Tokachi, and Meakan volcanoes, Hokkaido, Japan. Repeated measurements at each volcano gave a consistent composition with ±10-30% errors, depending on the stability of the background atmospheric conditions. Fumarolic gas samples were also collected at the Tokachi volcano by a conventional method, and we found a good agreement (the difference <10%) between the composition estimated by the multi-sensor technique and conventional method. Those results demonstrated that concentration ratios of major volcanic gas species (i.e., H 2O, CO 2, and SO 2) and temperature can be estimated by the new technique without any complicated chemical analyses even for gases emitted from an inaccessible open vent. Estimation of a more detailed gas composition can be also achieved by the combination of alkaline filter techniques to measure Cl/F/S ratios in the plume and other sensors for H 2S and H 2.

  16. Study on Indirect Measuring Technology of EAF Steelmaking Decarburization Rate by Off-gas Analysis Technique in Hot State Experiment

    NASA Astrophysics Data System (ADS)

    Dong, Kai; Liu, Wenjuan; Zhu, Rong

    2015-10-01

    In this paper, measurement method of EAF Steelmaking decarburization rate is studied. Because of the fuel gas blown and air mixed, the composition of hot temperature off-gas is measurand unreally, and the flow rate is unknown too, the direct measurement of EAF decarburization rate by furnace gas analysis is unrealized. Firstly, the off-gas generation process is discussed. After that, dynamic concentration of CO2, CO, and O2 in off-gas and EAF oxygen supply rate are monitored in real time. Finally, the concentration and volume flow rate of off-gas are obtained to measure the EAF decarburization rate indirectly. The results of the hot state experiments show that the decarburization rate in oxidization step can reach up to about 0.53 mol/s, and the forecasting carbon concentration is 1.14% corresponding to the average carbon concentration (1.43%) in finial metal samples. The measurement of decarburization rate by off-gas analysis technique can be reasonable in EAF production process.

  17. 3D Numerical study on the hollow profile polymer extrusion forming based on the gas-assisted technique

    NASA Astrophysics Data System (ADS)

    Ren, Z.; Huang, X. Y.; Liu, H. S.

    2016-07-01

    In this study, gas-assisted extrusion method was introduced into the extrusion of the hollow profiles. To validate the feasibility of the new extrusion method, 3D numerical simulation of the hollow profiles based on gas-assisted technique was carried out by using the finite element method. The Phan-Thien-Tanner (PTT) mode was selected as the construction equation. In the simulations, the physical field distributions of four different extrusion modes were obtained and analyzed. Results showed that the extrudate effect of traditional no gas- assisted mode was poor because the extrudate swell phenomenon is obvious and the physical field values are larger. For the gas-assisted of the inner wall, the extrudate swell of the melt was more obvious than that of the traditional no gas-assisted mode on account of the no-slip boundary condition on the outer wall. For the gas-assisted of the outer wall, the dimple effect of the inner wall is more obvious owing to the no-slip boundary condition on the inner wall. However, the extrusion effect of the double walls gas-assisted mode is very good because of the full-slip effect on the both walls.

  18. Neuroanatomic and behavioral correlates of urinary dysfunction induced by vaginal distension in rats.

    PubMed

    Palacios, J L; Juárez, M; Morán, C; Xelhuantzi, N; Damaser, M S; Cruz, Y

    2016-05-01

    The aim of the present study was to use a model of simulated human childbirth in rats to determine the damage to genitourinary structures and behavioral signs of urinary dysfunction induced by vaginal distension (VD) in female rats. In experiment 1, the length of the genitourinary tract and the nerves associated with it were measured immediately after simulated human delivery induced by VD or sham (SH) procedures. Electroneurograms of the dorsal nerve of the clitoris (DNC) were also recorded. In experiment 2, histological characteristics of the bladder and major pelvic ganglion of VD and SH rats were evaluated. In experiment 3, urinary parameters were determined in conscious animals during 6 h of dark and 6 h of light before and 3 days after VD or SH procedures. VD significantly increased distal vagina width (P < 0.001) and the length of the motor branch of the sacral plexus (P < 0.05), DNC (P < 0.05), and vesical nerves (P < 0.01) and decreased DNC frequency and amplitude of firing. VD occluded the pelvic urethra, inducing urinary retention, hematomas in the bladder, and thinness of the epithelial (P < 0.05) and detrusor (P < 0.01) layers of the bladder. Major pelvic ganglion parameters were not modified after VD. Rats dripped urine in unusual places to void, without the stereotyped behavior of micturition after VD. The neuroanatomic injuries after VD occur alongside behavioral signs of urinary incontinence as determined by a new behavioral tool for assessing micturition in conscious animals. PMID:26936873

  19. Effects of wall distensibility in hemodynamic simulations of an arteriovenous fistula.

    PubMed

    McGah, Patrick M; Leotta, Daniel F; Beach, Kirk W; Aliseda, Alberto

    2014-06-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is in part a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. The current study presents fluid-structure interaction (FSI) simulations of a patient-specific model of a mature arteriovenous fistula reconstructed from 3D ultrasound scans. The FSI results are compared with previously published data of the same model but with rigid walls. Ultrasound-derived wall motion measurements are also used to validate the FSI simulations of the wall motion. Very large time-averaged shear stresses, 10-15 Pa, are calculated at the fistula anastomosis in the FSI simulations, values which are much larger than what is typically thought to be the normal homeostatic shear stress in the peripheral vasculature. Although this result is systematically lower by as much as 50% compared to the analogous rigid-walled simulations, the inclusion of distensible vessel walls in hemodynamic simulations does not reduce the high anastomotic shear stresses to "normal" values. Therefore, rigid-walled analyses may be acceptable for identifying high shear regions of arteriovenous fistulae. PMID:24037281

  20. Effect of DSS-induced colitis on visceral sensitivity to colorectal distension in mice.

    PubMed

    Larsson, M H; Rapp, L; Lindström, E

    2006-02-01

    The present study aimed at evaluating the effect of dextran sodium sulphate (DSS)-induced colitis on visceral sensitivity, measured as the visceromotor response (VMR) to colorectal distension (CRD) in BALB/c and C57Bl/6 male mice. Inflammation was induced by the addition of 4% DSS to the drinking water for 5 (C57Bl/6) or 6-7 days (BALB/c). Parallel groups were used to monitor histopathological changes and visceral sensitivity. Pseudo-affective visceral pain responses were evoked using an increasing phasic CRD paradigm (10-60 mmHg) in conscious mice on predetermined days (pretreatment controls, 12, 16, 20, 30, 40 and 51). In both mouse strains, significant histopathological changes developed between days 2 and 5 of DSS treatment, and persisted until day 12 (P < 0.05). On day 15, inflammatory scores were reduced by about 50%. Despite evidence of inflammation in DSS-treated mice, no differences could be shown in the VMR to CRD between DSS-treated mice and controls at any time point tested. In addition, no differences were seen before and after DSS treatment in the same group of mice. In conclusion, these data suggest that DSS-induced colonic inflammation does not affect the visceral sensitivity to CRD, neither at short or long term, in BALB/c or C57Bl/6 male mice.

  1. Effects of Wall Distensibility in Hemodynamic Simulations of an Arteriovenous Fistula

    PubMed Central

    McGah, Patrick M.; Leotta, Daniel F.; Beach, Kirk W.; Aliseda, Alberto

    2013-01-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is in part a process to restore the mechanical stresses to some preferred level, i.e. mechanical homeostasis. The current study presents fluid-structure interaction (FSI) simulations of a patient-specific model of a mature arteriovenous fistula reconstructed from 3D ultrasound scans. The FSI results are compared with previously published data of the same model but with rigid walls. Ultrasound-derived wall motion measurements are also used to validate the FSI simulations of the wall motion. Very large time-averaged shear stresses, 10–15 Pa, are calculated at the fistula anastomosis in the FSI simulations, values which are much larger than what is typically thought to be the normal homeostatic shear stress in the peripheral vasculature. Although this result is systematically lower by as much as 50% compared to the analogous rigid-walled simulations, the inclusion of distensible vessel walls in hemodynamic simulations does not reduce the high anastomotic shear stresses to “normal” values. Therefore, rigid-walled analyses may be acceptable for identifying high shear regions of arteriovenous fistulae. PMID:24037281

  2. Distensibility of hepatic venous resistance sites and consequences on portal pressure.

    PubMed

    Greenway, C V; Lautt, W W

    1988-03-01

    Hepatic venous resistance was measured in cats anesthetized with pentobarbital sodium during changes in hepatic blood flow and in inferior vena cava (IVC) pressure, in an attempt to explain the variable and partial transmission of pressure from IVC to portal vein. Problems with earlier explanations based on a "vascular waterfall" or a "Starling resistor" are discussed. Our data and previously published data can be explained by the hypothesis that hepatic venous resistance decreases as the resistance site is distended by the pressure within the resistance vessels. The product of resistance and distending pressure was a constant. This constant equals the resistance at unit-distending pressure, and it is an index of active contraction of the resistance sites in acute experiments. It is increased during infusions of norepinephrine, and it is higher in innervated than in denervated livers. A distensible hepatic venous resistance is a passive mechanism for partial autoregulation of portal pressure. It also serves as a mechanism for regulation of the splanchnic capacitance response to changes in IVC pressure. PMID:3348424

  3. Chemometric Profile of Root Extracts of Rhodiola imbricata Edgew. with Hyphenated Gas Chromatography Mass Spectrometric Technique

    PubMed Central

    Tayade, Amol B.; Dhar, Priyanka; Kumar, Jatinder; Sharma, Manu; Chauhan, Rajinder S.; Chaurasia, Om P.; Srivastava, Ravi B.

    2013-01-01

    Rhodiola imbricata Edgew. (Rose root or Arctic root or Golden root or Shrolo), belonging to the family Crassulaceae, is an important food crop and medicinal plant in the Indian trans-Himalayan cold desert. Chemometric profile of the n-hexane, chloroform, dichloroethane, ethyl acetate, methanol, and 60% ethanol root extracts of R. imbricata were performed by hyphenated gas chromatography mass spectrometry (GC/MS) technique. GC/MS analysis was carried out using Thermo Finnigan PolarisQ Ion Trap GC/MS MS system comprising of an AS2000 liquid autosampler. Interpretation on mass spectrum of GC/MS was done using the NIST/EPA/NIH Mass Spectral Database, with NIST MS search program v.2.0g. Chemometric profile of root extracts revealed the presence of 63 phyto-chemotypes, among them, 1-pentacosanol; stigmast-5-en-3-ol, (3β,24S); 1-teracosanol; 1-henteracontanol; 17-pentatriacontene; 13-tetradecen-1-ol acetate; methyl tri-butyl ammonium chloride; bis(2-ethylhexyl) phthalate; 7,8-dimethylbenzocyclooctene; ethyl linoleate; 3-methoxy-5-methylphenol; hexadecanoic acid; camphor; 1,3-dimethoxybenzene; thujone; 1,3-benzenediol, 5-pentadecyl; benzenemethanol, 3-hydroxy, 5-methoxy; cholest-4-ene-3,6-dione; dodecanoic acid, 3-hydroxy; octadecane, 1-chloro; ethanone, 1-(4-hydroxyphenyl); α-tocopherol; ascaridole; campesterol; 1-dotriacontane; heptadecane, 9-hexyl were found to be present in major amount. Eventually, in the present study we have found phytosterols, terpenoids, fatty acids, fatty acid esters, alkyl halides, phenols, alcohols, ethers, alkanes, and alkenes as the major group of phyto-chemotypes in the different root extracts of R. imbricata. All these compounds identified by GC/MS analysis were further investigated for their biological activities and it was found that they possess a diverse range of positive pharmacological actions. In future, isolation of individual phyto-chemotypes and subjecting them to biological activity will definitely prove fruitful results in

  4. Measurement techniques investigated for detection of hydrogen chloride gas in ambient air

    NASA Technical Reports Server (NTRS)

    Gregory, G. L.

    1976-01-01

    Nine basic techniques are discussed, ranging from concentration (parts per million) to dosage only (parts per million-seconds) measurement techniques. Data for each technique include lower detection limit, response time, instrument status, and in some cases, specificity. Several techniques discussed can detect ambient hydrogen chloride concentrations below 1 part per million with a response time of seconds.

  5. Micro-CT image-derived metrics quantify arterial wall distensibility reduction in a rat model of pulmonary hypertension

    NASA Astrophysics Data System (ADS)

    Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Haworth, Steven T.; Dawson, Christopher A.

    2000-04-01

    We developed methods to quantify arterial structural and mechanical properties in excised rat lungs and applied them to investigate the distensibility decrease accompanying chronic hypoxia-induced pulmonary hypertension. Lungs of control and hypertensive (three weeks 11% O2) animals were excised and a contrast agent introduced before micro-CT imaging with a special purpose scanner. For each lung, four 3D image data sets were obtained, each at a different intra-arterial contrast agent pressure. Vessel segment diameters and lengths were measured at all levels in the arterial tree hierarchy, and these data used to generate features sensitive to distensibility changes. Results indicate that measurements obtained from 3D micro-CT images can be used to quantify vessel biomechanical properties in this rat model of pulmonary hypertension and that distensibility is reduced by exposure to chronic hypoxia. Mechanical properties can be assessed in a localized fashion and quantified in a spatially-resolved way or as a single parameter describing the tree as a whole. Micro-CT is a nondestructive way to rapidly assess structural and mechanical properties of arteries in small animal organs maintained in a physiological state. Quantitative features measured by this method may provide valuable insights into the mechanisms causing the elevated pressures in pulmonary hypertension of differing etiologies and should become increasingly valuable tools in the study of complex phenotypes in small-animal models of important diseases such as hypertension.

  6. Increased carotid intima-media thickness and reduced distensibility in human class III obesity: independent and differential influences of adiposity and blood pressure on the vasculature.

    PubMed

    Moore, Xiao L; Michell, Danielle; Lee, Sabrina; Skilton, Michael R; Nair, Rajesh; Dixon, John B; Dart, Anthony M; Chin-Dusting, Jaye

    2013-01-01

    Carotid intima-media-thickness (cIMT) and carotid distensibility (distensibility), structural and functional properties of carotid arteries respectively, are early markers, as well as strong predictors of cardiovascular disease (CVD). The characteristic of these two parameters in individuals with BMI>40.0 kg/m(2) (Class III obesity), however, are largely unknown. The present study was designed to document cIMT and distensibility in this population and to relate these to other factors with established association with CVD in obesity. The study included 96 subjects (65 with BMI>40.0 kg/m(2) and 31, age- and gender-matched, with BMI of 18.5 to 30.0 kg/m(2)). cIMT and distensibility were measured by non-invasive high resolution ultrasonography, circulatory CD133(+)/KDR(+) angiogenic cells and endothelial microparticles (EMP) by flow cytometry, and plasma levels of adipokines, growth factors and cytokines by Luminex immunoassay kits. The study results demonstrated increased cIMT (0.62±0.11 mm vs. 0.54±0.08 mm, P = 0.0002) and reduced distensibility (22.52±10.79 10(-3)kpa(-1)vs. 29.91±12.37 10(-3)kpa(-1), P<0.05) in individuals with BMI>40.0 kg/m(2). Both cIMT and distensibility were significantly associated with traditional CVD risk factors, adiposity/adipokines and inflammatory markers but had no association with circulating angiogenic cells. We also demonstrated, for the first time, elevated plasma EMP levels in individuals with BMI>40.0 kg/m(2). In conclusion, cIMT is increased and distensibility reduced in Class III obesity with the changes predominantly related to conventional CVD risk factors present in this condition, demonstrating that both cIMT and distensibility remain as CVD markers in Class III obesity. PMID:23342053

  7. Increased Carotid Intima-Media Thickness and Reduced Distensibility in Human Class III Obesity: Independent and Differential Influences of Adiposity and Blood Pressure on the Vasculature

    PubMed Central

    Moore, Xiao L.; Michell, Danielle; Lee, Sabrina; Skilton, Michael R.; Nair, Rajesh; Dixon, John B.; Dart, Anthony M.; Chin-Dusting, Jaye

    2013-01-01

    Carotid intima-media-thickness (cIMT) and carotid distensibility (distensibility), structural and functional properties of carotid arteries respectively, are early markers, as well as strong predictors of cardiovascular disease (CVD). The characteristic of these two parameters in individuals with BMI>40.0 kg/m2 (Class III obesity), however, are largely unknown. The present study was designed to document cIMT and distensibility in this population and to relate these to other factors with established association with CVD in obesity. The study included 96 subjects (65 with BMI>40.0 kg/m2 and 31, age- and gender-matched, with BMI of 18.5 to 30.0 kg/m2). cIMT and distensibility were measured by non-invasive high resolution ultrasonography, circulatory CD133+/KDR+ angiogenic cells and endothelial microparticles (EMP) by flow cytometry, and plasma levels of adipokines, growth factors and cytokines by Luminex immunoassay kits. The study results demonstrated increased cIMT (0.62±0.11 mm vs. 0.54±0.08 mm, P = 0.0002) and reduced distensibility (22.52±10.79 10−3kpa−1 vs. 29.91±12.37 10−3kpa−1, P<0.05) in individuals with BMI>40.0 kg/m2. Both cIMT and distensibility were significantly associated with traditional CVD risk factors, adiposity/adipokines and inflammatory markers but had no association with circulating angiogenic cells. We also demonstrated, for the first time, elevated plasma EMP levels in individuals with BMI>40.0 kg/m2. In conclusion, cIMT is increased and distensibility reduced in Class III obesity with the changes predominantly related to conventional CVD risk factors present in this condition, demonstrating that both cIMT and distensibility remain as CVD markers in Class III obesity. PMID:23342053

  8. Increased carotid intima-media thickness and reduced distensibility in human class III obesity: independent and differential influences of adiposity and blood pressure on the vasculature.

    PubMed

    Moore, Xiao L; Michell, Danielle; Lee, Sabrina; Skilton, Michael R; Nair, Rajesh; Dixon, John B; Dart, Anthony M; Chin-Dusting, Jaye

    2013-01-01

    Carotid intima-media-thickness (cIMT) and carotid distensibility (distensibility), structural and functional properties of carotid arteries respectively, are early markers, as well as strong predictors of cardiovascular disease (CVD). The characteristic of these two parameters in individuals with BMI>40.0 kg/m(2) (Class III obesity), however, are largely unknown. The present study was designed to document cIMT and distensibility in this population and to relate these to other factors with established association with CVD in obesity. The study included 96 subjects (65 with BMI>40.0 kg/m(2) and 31, age- and gender-matched, with BMI of 18.5 to 30.0 kg/m(2)). cIMT and distensibility were measured by non-invasive high resolution ultrasonography, circulatory CD133(+)/KDR(+) angiogenic cells and endothelial microparticles (EMP) by flow cytometry, and plasma levels of adipokines, growth factors and cytokines by Luminex immunoassay kits. The study results demonstrated increased cIMT (0.62±0.11 mm vs. 0.54±0.08 mm, P = 0.0002) and reduced distensibility (22.52±10.79 10(-3)kpa(-1)vs. 29.91±12.37 10(-3)kpa(-1), P<0.05) in individuals with BMI>40.0 kg/m(2). Both cIMT and distensibility were significantly associated with traditional CVD risk factors, adiposity/adipokines and inflammatory markers but had no association with circulating angiogenic cells. We also demonstrated, for the first time, elevated plasma EMP levels in individuals with BMI>40.0 kg/m(2). In conclusion, cIMT is increased and distensibility reduced in Class III obesity with the changes predominantly related to conventional CVD risk factors present in this condition, demonstrating that both cIMT and distensibility remain as CVD markers in Class III obesity.

  9. Pore Scale and Continuum Modeling for Gas Flow Pattern obtained by Multi-Scale Optical Imaging Technique

    NASA Astrophysics Data System (ADS)

    Lazik, D.; Samani, S.; Geistlinger, H.

    2008-12-01

    A multi-scale optical imaging technique was developed allowing for the 2D observation of two phase flow in porous media at two different scales simultaneously: Using two coupled camera systems a 2D flow cell (0.5 x 0.5 m²) is recorded entirely at the bench scale and at the pore scale with a spatial resolution of 0.5 mm and 0.01 mm respectively. The technique is applied to study channelized gas flow in saturated 0.5mm glass beads. We analyze the phase distribution at the pore scale and derive a pixel-based method for the measurement of saturation at the larger scale. Pore-Scale-Models: Both a grain-size- and flow rate-dependent transition are observed in the gas flow pattern. Standard quasi-static criteria do not explain the experimental results, since they do not take into account the competition between stabilizing friction forces and destabilizing capillary and gravitational forces. Conceptualizing the steady state tortuous gas flow as core-annular flow and applying Hagen-Poiseuille flow for a straight capillary, we propose a flow rate and grain-size-dependent stability criterion (coherence condition) that accounts for the experimental results. Continuum Scale Models: The main objective of this paper is to test the validity of the continuum approach for two-fluid flow for macroscopic homogeneous media. Using a reasonable log-normal distribution of capillary radii that led to a matrix potential that fits the experimental steady-state capillary pressure, the continuum model (TOUGH2) was able to describe the functional form of the dynamical gas volume, an integral flow property, as a function of the flow rate for the 0.5mm glass beads. On the other hand, the continuum model fails to describe the spatial-temporal distribution of the gas flow. For the first time, we were able to quantify the plateau-like gas distribution using optical tomography. This result is in strong contradiction to the Gaussian-like distribution obtained from the continuum model. Both

  10. Neonatal lethality of neural crest cell-specific Rest knockout mice is associated with gastrointestinal distension caused by aberrations of myenteric plexus.

    PubMed

    Aoki, Hitomi; Hara, Akira; Oomori, Yoshiyuki; Shimizu, Yasutake; Yamada, Yasuhiro; Kunisada, Takahiro

    2014-10-01

    RE1-silencing transcription factor (REST), also known as NRSF (neuron-restrictive silencer factor), is a well-known transcriptional repressor of neural genes. Rest null mice have embryonic lethality which prevents further investigations of the functions of the Rest gene in vivo. We studied neonatal but not embryonic lethality that was characterized by gastrointestinal tract dilation in the neural crest cell (NCC)-specific Rest conditional knockout (CKO) mice. While no histological abnormalities except the thinning of the digestive tract as a consequence of the gas accumulation were found in the digestive tract of the mutant mice, they do not have proper gastric retention after oral dye administration and the reduction of acetylcholinesterase (AChE) activity in NCC-derived myenteric plexus in the stomach was detected. High CO2 concentration in the dilated digestive tract of the Rest CKO mice indicates a failure of gut function by underdeveloped cholinergic transmission in the enteric nervous system. The observed gastrointestinal distension phenotype provides a model for understanding the genetic and molecular basis of NCC defects in humans. PMID:25135772

  11. Comparison of inert-gas-fusion and modified Kjeldahl techniques for determination of nitrogen in niobium alloys

    NASA Technical Reports Server (NTRS)

    Merkle, E. J.; Graab, J. W.; Davis, W. F.

    1974-01-01

    This report compares results obtained for the determination of nitrogen in a selected group of niobium-base alloys by the inert-gas-fusion and the Kjeldahl procedures. In the inert-gas-fusion procedure the sample is heated to approximately 2700 C in a helium atmosphere in a single-use graphite crucible. A platinum flux is used to facilitate melting of the sample. The Kjeldahl method consisted of a rapid decomposition with a mixture of hydrofluoric acid, phosphoric acid, and potassium chromate; distillation in the presence of sodium hydroxide; and highly sensitive spectrophotometry with nitroprusside-catalyzed indophenol. In the 30- to 80-ppm range, the relative standard deviation was 5 to 7 percent for the inert-gas-fusion procedure and 2 to 8 percent for the Kjeldahl procedure. The agreement of the nitrogen results obtained by the two techniques is considered satisfactory.

  12. Nitriding molybdenum: Effects of duration and fill gas pressure when using 100-Hz pulse DC discharge technique

    NASA Astrophysics Data System (ADS)

    Ikhlaq, U.; R., Ahmad; Shafiq, M.; Saleem, S.; S. Shah, M.; Hussain, T.; A. Khan, I.; K., Abbas; S. Abbas, M.

    2014-10-01

    Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are used for the structural and morphological analysis of the nitrided layers. Vickers' microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar (1 bar = 105 Pa). A considerable increase in surface microhardness (approximately by a factor of 2) is observed for longer duration (10 h) and 2-mbar pressure. Longer duration (10 h) and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.

  13. Per-fluorinated sulfonic acid/PTFE copolymer studied by positron annihilation lifetime and gas permeation techniques

    NASA Astrophysics Data System (ADS)

    Mohamed, Hamdy F. M.; Abdel-Hady, E. E.; Ohira, A.

    2015-06-01

    The mechanism of gas permeation in per-fluorinated sulfonic acid/PTFE copolymer Fumapem® membranes for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Three different samples, Fumapem® F-950, F-1050 and F-14100 membranes with ion exchange capacity (IEC) = 1.05, 0.95 and 0.71 meq/g, respectively were used after drying. Free volume was quantified using the positron annihilation lifetime (PAL) technique and gas permeabilities were measured for O2 and H2 as function of temperature. Good linear correlation between the logarithm of the permeabilities at different temperatures and reciprocal free volume indicate that gas permeation in dry Fumapem® is governed by the free volume. Nevertheless permeabilities are much smaller than the corresponding flexible chain polymer with a similar free volume size due to stiff chains of the perfluoroethylene backbone.

  14. Acupuncture transcutaneous electrical nerve stimulation reduces discomfort associated with barostat-induced rectal distension: A randomized-controlled study

    PubMed Central

    Leung, Wing-Wa; Jones, Alice YM; Ng, Simon SM; Wong, Cherry YN; Lee, Janet FY

    2013-01-01

    AIM: To explore the effectiveness of acupuncture transcutaneous electrical nerve stimulation (Acu-TENS), a non-invasive modality in reduction of rectal discomfort during barostat-induced rectal distension. METHODS: Forty healthy subjects were randomized to receive 45 min of either Acu-TENS or placebo-TENS (no electrical output) over acupuncture points Hegu (large-intestine 4), Neiguan (pericardium 6) and Zusanli (stomach 36). A balloon catheter attached to a dual-drive barostat machine was then inserted into the subjects’ rectum. A step-wise (4 mmHg) increase in balloon pressure was induced until maximal tolerable or 48 mmHg. Visual analogue scale and a 5-point subjective discomfort scale (no perception, first perception of distension, urge to defecate, discomfort/pain and extreme pain) were used to assess rectal discomfort at each distension pressure. Blood beta-endorphin levels were measured before, immediately after intervention, at 24 mmHg and at maximal tolerable distension pressure. RESULTS: There was no difference in the demographic data and baseline plasma beta-endorphin levels between the two groups. Perception threshold levels were higher in the Acu-TENS group when compared to the placebo group, but the difference reached statistical significance only at the sensations “urge to defecate” and “pain”. The distension pressures recorded at the “urge to defecate” sensation for the Acu-TENS and placebo-TENS groups were 28.0 ± 4.5 mmHg and 24.6 ± 5.7 mmHg, respectively (P = 0.043); and the pressures recorded for the “pain” sensation for these two groups were 36.0 ± 4.2 mmHg and 30.5 ± 4.3 mmHg respectively (P = 0.002). Compared to the placebo group, a higher number of participants in the Acu-TENS group tolerated higher distension pressures (> 40 mmHg) (65% in Acu-TENS vs 25% in placebo, P = 0.02). The plasma beta-endorphin levels of the Acu-TENS group were significantly higher than that of the placebo group at barostat inflation pressure of

  15. New Natural Gas Storage and Transportation Capabilities Utilizing Rapid Methane Hydrate Formation Techniques

    SciTech Connect

    Brown, T.D.; Taylor, C.E.; Bernardo, M.

    2010-01-01

    Natural gas (methane as the major component) is a vital fossil fuel for the United States and around the world. One of the problems with some of this natural gas is that it is in remote areas where there is little or no local use for the gas. Nearly 50 percent worldwide natural gas reserves of ~6,254.4 trillion ft3 (tcf) is considered as stranded gas, with 36 percent or ~86 tcf of the U.S natural gas reserves totaling ~239 tcf, as stranded gas [1] [2]. The worldwide total does not include the new estimates by U.S. Geological Survey of 1,669 tcf of natural gas north of the Arctic Circle, [3] and the U.S. ~200,000 tcf of natural gas or methane hydrates, most of which are stranded gas reserves. Domestically and globally there is a need for newer and more economic storage, transportation and processing capabilities to deliver the natural gas to markets. In order to bring this resource to market, one of several expensive methods must be used: 1. Construction and operation of a natural gas pipeline 2. Construction of a storage and compression facility to compress the natural gas (CNG) at 3,000 to 3,600 psi, increasing its energy density to a point where it is more economical to ship, or 3. Construction of a cryogenic liquefaction facility to produce LNG, (requiring cryogenic temperatures at <-161 °C) and construction of a cryogenic receiving port. Each of these options for the transport requires large capital investment along with elaborate safety systems. The Department of Energy's Office of Research and Development Laboratories at the National Energy Technology Laboratory (NETL) is investigating new and novel approaches for rapid and continuous formation and production of synthetic NGHs. These synthetic hydrates can store up to 164 times their volume in gas while being maintained at 1 atmosphere and between -10 to -20°C for several weeks. Owing to these properties, new process for the economic storage and transportation of these synthetic hydrates could be envisioned

  16. Effect of nonsteroidal anti-inflammatory drugs on colorectal distension-induced visceral pain

    PubMed Central

    Baskın, Veysel; Bilge, S. Sırrı; Bozkurt, Ayhan; Akyüz, Bahar; Ağrı, Arzu Erdal; Güzel, Hasan; İlkaya, Fatih

    2016-01-01

    Objectives: To investigate nonsteroidal anti-inflammatory drugs effectiveness in colorectal distension (CRD)-induced visceral pain model. Materials and Methods: Male Sprague–Dawley (250–300 g) rats were anesthetized with ketamine (50 mg/kg, intraperitoneally [i.p.]) and chlorpromazine (25 mg/kg, i.p.). Two bipolar Teflon-coated Ni/Cr wire electrodes (80-M diameter) were placed in the abdominal external oblique muscle for the recording of electromyography. Jugular vein catheter was placed for the administration of drugs. CRD method was applied to evaluate of visceral pain. All drugs (paracetamol, meloxicam, metamizole, and dexketoprofen) administered intravenously. Results: Paracetamol 200, 400, and 600 mg/kg did not change the visceromotor response (VMR) when compare with the control group. Meloxicam 2 and 4 mg/kg showed no effect but at doses of 6 mg/kg meloxicam significantly ([51.9 ± 6.4%] [P < 0.001]) decreased VMR compared with the control group. Metamizole 200 mg/kg did not change responses but dose of 400 and 600 mg/kg metamizole reduced VMR. Dexketoprofen 2 and 4 mg/kg did not cause a change in VMR but 6 mg/kg dose significantly reduced response compared with the control group ([43.9 ± 3.9%, 36.8 ± 2.8%, 34.8 ± 2.5%, 42.1 ± 4.8%, 40.7 ± 3.5%, 36.4 ± 2.7%, and 26.1 ± 2.2%]; from 10 min to 70 min, respectively, [P < 0.05]). Conclusion: Metamizole, dexketoprofen and meloxicam show antinociceptive effect with different duration of action on CRD-induced visceral pain model. This condition can be explained due to different chemical structures and different mechanisms which play a role in modulation of pain. PMID:27114637

  17. Effect of ageing on left ventricular compliance and distensibility in healthy sedentary humans

    PubMed Central

    Fujimoto, Naoki; Hastings, Jeffrey L; Bhella, Paul S; Shibata, Shigeki; Gandhi, Nainesh K; Carrick-Ranson, Graeme; Palmer, Dean; Levine, Benjamin D

    2012-01-01

    Healthy, but sedentary ageing leads to marked atrophy and stiffening of the heart, with substantially reduced cardiac compliance; but the time course of when this process occurs during normal ageing is unknown. Seventy healthy sedentary subjects (39 female; 21–77 years) were recruited from the Dallas Heart Study, a population-based, random community sample and enriched by a second random sample from employees of Texas Health Resources. Subjects were highly screened for co-morbidities and stratified into four groups according to age: G21−34: 21–34 years, G35−49: 35–49 years, G50−64: 50–64 years, G≥65: ≥65 years. All subjects underwent invasive haemodynamic measurements with right heart catheterization to define Starling and left ventricular (LV) pressure–volume curves. LV end-diastolic volumes (EDV) were measured by echocardiography at baseline, −15 and −30 mmHg lower-body negative pressure, and 15 and 30 ml kg−1 saline infusion with simultaneous measurements of pulmonary capillary wedge pressure. There were no differences in heart rate or blood pressures among the four groups at baseline. Baseline EDV index was smaller in G≥65 than other groups. LV diastolic pressure–volume curves confirmed a substantially greater LV compliance in G21−34 compared with G50−64 and G≥65, resulting in greater LV volume changes with preload manipulations. Although LV chamber compliance in G50−64 and G≥65 appeared identical, pressure–volume curves were shifted leftward, toward a decreased distensibility, with increasing age. These results suggest that LV stiffening in healthy ageing occurs during the transition between youth and middle-age and becomes manifest between the ages of 50 to 64. Thereafter, this LV stiffening is followed by LV volume contraction and remodelling after the age of 65. PMID:22331419

  18. Analysis of chemical signals in red fire ants by gas chromatography and pattern recognition techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The combination of gas chromatography and pattern recognition (GC/PR) analysis is a powerful tool for investigating complicated biological problems. Clustering, mapping, discriminant development, etc. are necessary to analyze realistically large chromatographic data sets and to seek meaningful relat...

  19. Formation of single-wall carbon nanotubes in Ar and nitrogen gas atmosphere by using laser furnace technique

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Asai, N.; Kataura, H.; Achiba, Y.

    2007-07-01

    The formation of single-wall carbon nanotubes (SWNTs) by using laser vaporization technique in different ambient gas atmosphere was investigated. SWNTs were prepared with Rh/Pd (1.2/1.2 atom%)-carbon composite rod in Ar and nitrogen gas atmosphere, respectively. Raman spectra of raw carbon materials including SWNTs and photoluminescence mapping of dispersed SWNTs in a surfactant solution demonstrate that the diameter distribution of SWNTs prepared in Ar atmosphere is narrower than those obtained by using CVD technique (e.g. HiPco nanotube), even when the ambient temperature is as high as 1150 ?C. It was also found that nitrogen atmosphere gives wider diameter distribution of SWNTs than that obtained with Ar atmosphere. Furthermore, the relative yield of fullerenes (obtained as byproducts) is investigated by using HPLC (high-performance liquid chromatography) technique. It was found that the relative yield of higher fullerenes becomes lower, when nitrogen is used as an ambient gas atmosphere. Based on these experimental findings, a plausible formation mechanism of SWNTs is discussed.

  20. A simple technique for continuous measurement of time-variable gas transfer in surface waters

    USGS Publications Warehouse

    Tobias, C.R.; Böhlke, J.K.; Harvey, J.W.; Busenberg, E.

    2009-01-01

    Mass balance models of dissolved gases in streams, lakes, and rivers serve as the basis for estimating wholeecosystem rates for various biogeochemical processes. Rates of gas exchange between water and the atmosphere are important and error-prone components of these models. Here we present a simple and efficient modification of the SF6 gas tracer approach that can be used concurrently while collecting other dissolved gas samples for dissolved gas mass balance studies in streams. It consists of continuously metering SF 6-saturated water directly into the stream at a low rate of flow. This approach has advantages over pulse injection of aqueous solutions or bubbling large amounts of SF6 into the stream. By adding the SF 6 as a saturated solution, we minimize the possibility that other dissolved gas measurements are affected by sparging and/or bubble injecta. Because the SF6 is added continuously we have a record of changing gas transfer velocity (GTV) that is contemporaneous with the sampling of other nonconservative ambient dissolved gases. Over a single diel period, a 30% variation in GTV was observed in a second-order stream (Sugar Creek, Indiana, USA). The changing GTV could be attributed in part to changes in temperature and windspeed that occurred on hourly to diel timescales.

  1. A simple technique for continuous measurement of time-variable gas transfer in surface waters

    USGS Publications Warehouse

    Bohlke, Johnkarl F.; Harvey, Judson W.; Busenberg, Eurybiades; Tobias, Craig R.

    2009-01-01

    Mass balance models of dissolved gases in streams, lakes, and rivers serve as the basis for estimating wholeecosystem rates for various biogeochemical processes. Rates of gas exchange between water and the atmosphere are important and error-prone components of these models. Here we present a simple and efficient modification of the SF6 gas tracer approach that can be used concurrently while collecting other dissolved gas samples for dissolved gas mass balance studies in streams. It consists of continuously metering SF6-saturated water directly into the stream at a low rate of flow. This approach has advantages over pulse injection of aqueous solutions or bubbling large amounts of SF6 into the stream. By adding the SF6 as a saturated solution, we minimize the possibility that other dissolved gas measurements are affected by sparging and/or bubble injecta. Because the SF6 is added continuously we have a record of changing gas transfer velocity (GTV) that is contemporaneous with the sampling of other nonconservative ambient dissolved gases. Over a single diel period, a 30% variation in GTV was observed in a second-order stream (Sugar Creek, Indiana, USA). The changing GTV could be attributed in part to changes in temperature and windspeed that occurred on hourly to diel timescales.

  2. Dual SAW sensor technique for determining mass and modulus changes in thin silicate films during gas adsorption

    SciTech Connect

    Hietala, S.L.; Hietala, V.M.; Brinker, C.J.

    2000-01-10

    Surface acoustic wave (SAW) sensors, which are sensitive to a variety of surface changes, have been widely used for chemical and physical sensing. The ability to control or compensate for the many surface forces has been instrumental in collecting valid data. In cases where it is not possible to neglect certain effects, such as frequency drift with temperature, methods such as the dual sensor technique have been utilized. This paper describes a novel use of a dual sensor technique, using two sensor materials, Quartz and GaAs, to separate out the contributions of mass and modulus of the frequency change during gas adsorption experiments. The large modulus change in the film calculated using this technique, and predicted by the Gassmann equation, provide a greater understanding of the challenges of SAW sensing.

  3. Application of Condition-Based Monitoring Techniques for Remote Monitoring of a Simulated Gas Centrifuge Enrichment Plant

    SciTech Connect

    Hooper, David A; Henkel, James J; Whitaker, Michael

    2012-01-01

    This paper presents research into the adaptation of monitoring techniques from maintainability and reliability (M&R) engineering for remote unattended monitoring of gas centrifuge enrichment plants (GCEPs) for international safeguards. Two categories of techniques are discussed: the sequential probability ratio test (SPRT) for diagnostic monitoring, and sequential Monte Carlo (SMC or, more commonly, particle filtering ) for prognostic monitoring. Development and testing of the application of condition-based monitoring (CBM) techniques was performed on the Oak Ridge Mock Feed and Withdrawal (F&W) facility as a proof of principle. CBM techniques have been extensively developed for M&R assessment of physical processes, such as manufacturing and power plants. These techniques are normally used to locate and diagnose the effects of mechanical degradation of equipment to aid in planning of maintenance and repair cycles. In a safeguards environment, however, the goal is not to identify mechanical deterioration, but to detect and diagnose (and potentially predict) attempts to circumvent normal, declared facility operations, such as through protracted diversion of enriched material. The CBM techniques are first explained from the traditional perspective of maintenance and reliability engineering. The adaptation of CBM techniques to inspector monitoring is then discussed, focusing on the unique challenges of decision-based effects rather than equipment degradation effects. These techniques are then applied to the Oak Ridge Mock F&W facility a water-based physical simulation of a material feed and withdrawal process used at enrichment plants that is used to develop and test online monitoring techniques for fully information-driven safeguards of GCEPs. Advantages and limitations of the CBM approach to online monitoring are discussed, as well as the potential challenges of adapting CBM concepts to safeguards applications.

  4. Estimation of VOC emissions from produced-water treatment ponds in Uintah Basin oil and gas field using modeling techniques

    NASA Astrophysics Data System (ADS)

    Tran, H.; Mansfield, M. L.; Lyman, S. N.; O'Neil, T.; Jones, C. P.

    2015-12-01

    Emissions from produced-water treatment ponds are poorly characterized sources in oil and gas emission inventories that play a critical role in studying elevated winter ozone events in the Uintah Basin, Utah, U.S. Information gaps include un-quantified amounts and compositions of gases emitted from these facilities. The emitted gases are often known as volatile organic compounds (VOCs) which, beside nitrogen oxides (NOX), are major precursors for ozone formation in the near-surface layer. Field measurement campaigns using the flux-chamber technique have been performed to measure VOC emissions from a limited number of produced water ponds in the Uintah Basin of eastern Utah. Although the flux chamber provides accurate measurements at the point of sampling, it covers just a limited area of the ponds and is prone to altering environmental conditions (e.g., temperature, pressure). This fact raises the need to validate flux chamber measurements. In this study, we apply an inverse-dispersion modeling technique with evacuated canister sampling to validate the flux-chamber measurements. This modeling technique applies an initial and arbitrary emission rate to estimate pollutant concentrations at pre-defined receptors, and adjusts the emission rate until the estimated pollutant concentrations approximates measured concentrations at the receptors. The derived emission rates are then compared with flux-chamber measurements and differences are analyzed. Additionally, we investigate the applicability of the WATER9 wastewater emission model for the estimation of VOC emissions from produced-water ponds in the Uintah Basin. WATER9 estimates the emission of each gas based on properties of the gas, its concentration in the waste water, and the characteristics of the influent and treatment units. Results of VOC emission estimations using inverse-dispersion and WATER9 modeling techniques will be reported.

  5. Investigation Of A Mercury Speciation Technique For Flue Gas Desulfurization Materials

    EPA Science Inventory

    Most of the synthetic gypsum generated from wet flue gas desulfurization (FGD) scrubbers is currently being used for wallboard production. Because oxidized mercury is readily captured by the wet FGD scrubber, and coal-fired power plants equipped with wet scrubbers desire to bene...

  6. Size Estimation and Time Evolution of Large Size Rare Gas Clusters by Rayleigh Scattering Techniques

    NASA Astrophysics Data System (ADS)

    Liu, Bing-Chen; Zhu, Pin-Pin; Li, Zhao-Hui; Ni, Guo-Quan; Xu, Zhi-Zhan

    2002-05-01

    Large rare gas clusters Arn, Krn and Xen were produced at room temperature in the process of supersonic adiabatic expansion. The cluster size is examined by a Rayleigh scattering experiment. Power variations of the average cluster size 0256-307X/19/5/316/art16 with the gas backing pressure P0 give size scaling as 0256-307X/19/5/316/art16 ∝P02.0, resulting in the largest cluster sizes which are estimated in the present work to be about 1.5×104, 2.6×104 and 4.0×104 atoms (the corresponding diameters of the cluster spheres are about 9, 13 and 17 nm) for Ar, Kr and Xe, respectively. A time resolving Rayleigh scattering experiment was conducted to investigate the time evolution of cluster formation and decay processes. A surprising two-plateau structure of the time evolution characteristic of cluster formation and decay processes of Kr and Xe clusters was revealed as compared with a ``normal'' single structure for the case of Ar gas. In the second plateau, the intensity of the scattered light is enhanced greatly, by even as much as 62 times, over that in the first plateau, indicating a significant increase in cluster size. This finding supports the importance of nuclei in the gas condensation process and may be helpful for further insight into the phenomenon of clustering.

  7. Investigation of entrainment and thermal properties of a cryogenic dense-gas cloud using optical measurement techniques.

    PubMed

    Kunsch, J P; Rösgen, T

    2006-09-01

    Cryogenic dense-gas clouds have been investigated in a heavy-gas channel under controlled source and ambient conditions. Advantage is taken from new, non-intrusive optical measurement techniques (e.g. image correlation velocimetry, ICV, and background oriented Schlieren, BOS) providing detailed pictures of the temperature and velocity field in relevant regions of the cloud. The ice particles in the cloud, formed by nucleation, represent a natural seeding to be used as tracers, which have the advantage of behaving passively. Two layers can be identified in a cryogenic gas cloud: a lower cold layer, which is visible due to the presence of ice particles, and an invisible upper layer, where the ice particles have melted, mostly due to heat addition by air entrainment into the upper layer. A two-layer model has been applied to a generic element of the cloud, where detailed experimental data regarding velocity and temperature are available. Thermal- and dilution behaviour can be interpreted by means of the model which is presented in detail. A global entrainment parameter is deduced allowing a simple comparison with existing experimental information obtained by other traditional experimental techniques. The numerical values of the present entrainment parameter agree well with the correlations proposed by other authors. Thermal effects, such as heat transfer from the ground, appear to be very important. In addition, the visible height of the cloud can be predicted in relative good agreement with the experimental observations, by means of a thermal balance including the phase transition of the ice particles.

  8. A new technique for measuring gas conversion factors for hydrocarbon mass flowmeters

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Sprinkle, D. R.

    1983-01-01

    A technique for measuring calibration conversion factors for hydrocarbon mass flowmeters was developed. It was applied to a widely used type of commercial thermal mass flowmeter for hydrocarbon gases. The values of conversion factors for two common hydrocarbons measured using this technique are in good agreement with the empirical values cited by the manufacturer. Similar agreements can be expected for all other hydrocarbons. The technique is based on Nernst theorem for matching the partial pressure of oxygen in the combustion product gases with that in normal air. It is simple, quick and relatively safe--particularly for toxic/poisonous hydrocarbons.

  9. Estimating fermentation characteristics and nutritive value of ensiled and dried pomegranate seeds for ruminants using in vitro gas production technique

    PubMed Central

    Taher-Maddah, M.; Maheri-Sis, N.; Salamatdoustnobar, R.; Ahmadzadeh, A.

    2012-01-01

    The purpose of this study was to determine the chemical composition and estimation of fermentation characteristics and nutritive value of ensiled and dried pomegranate seeds using in vitro gas production technique. Samples were collected, mixed, processed (ensiled and dried) and incubated in vitro with rumen liquor taken from three fistulated Iranian native (Taleshi) steers at 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h. The results showed that ensiling lead to significant increase in gas production of pomegranate seeds at all incubation times. The gas volume at 24 h incubation, were 25.76 and 17.91 ml/200mg DM for ensiled and dried pomegranate seeds, respectively. The gas production rate (c) also was significantly higher for ensiled groups than dried (0.0930 vs. 0.0643 ml/h). The organic matter digestibility (OMD), metabolizable energy (ME), net energy for lactation (NEL) and short chain fatty acids (SCFA) of ensiled pomegranate seeds were significantly higher than that of dried samples (43.15%, 6.37 MJ/kg DM, 4.43 MJ/kg DM, 0.5553 mmol for ensiled samples vs. 34.62%, 5.10 MJ/kg DM, 3.56 MJ/kg DM, 0.3680 mmol for dried samples, respectively). It can be concluded that ensiling increases the nutritive value of pomegranate seeds. PMID:26623290

  10. Yb-doped large-mode-area laser fiber fabricated by halide-gas-phase-doping technique

    NASA Astrophysics Data System (ADS)

    Peng, Kun; Wang, Yuying; Ni, Li; Wang, Zhen; Gao, Cong; Zhan, Huan; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2015-06-01

    In this manuscript, we designed a rare-earth-halide gas-phase-doping setup to fabricate a large-mode-area fiber for high power laser applications. YbCl3 and AlCl3 halides are evaporated, carried respectively and finally mixed with usual host gas material SiCl4 at the hot zone of MCVD system. Owing to the all-gas-phasing reaction process and environment, the home-made Yb-doped fiber preform has a homogeneous large core and modulated refractive index profile to keep high beam quality. The drawn fiber core has a small numerical aperture of 0.07 and high Yb concentration of 9500 ppm. By using a master oscillator power amplifier system, nearly kW-level (951 W) laser output power was obtained with a slope efficiency of 83.3% at 1063.8 nm, indicating the competition and potential of the halide-gas-phase-doping technique for high power laser fiber fabrication.

  11. Inhibitory Effects and Sympathetic Mechanisms of Distension in the Distal Organs on Small Bowel Motility and Slow Waves in Canine.

    PubMed

    Song, Jun; Yin, Jieyun; Chen, Jiande D Z

    2015-12-01

    Rectal distension (RD) is known to induce intestinal dysmotility. Few studies were performed to compare effects of RD, colon distension (CD) and duodenal distension (DD) on small bowel motility. This study aimed to investigate effects and underlying mechanisms of distensions in these regions on intestinal motility and slow waves. Eight dogs chronically implanted with a duodenal fistula, a proximal colon fistula, and intestinal serosal electrodes were studied in six sessions: control, RD, CD, DD, RD + guanethidine, and CD + guanethidine. Postprandial intestinal contractions and slow waves were recorded for the assessment of intestinal motility. The electrocardiogram was recorded for the assessment of autonomic functions. (1) Isobaric RD and CD suppressed intestinal contractions (contractile index: 6.0 ± 0.4 with RD vs. 9.9 ± 0.9 at baseline, P = 0.001, 5.3 ± 0.2 with CD vs. 7.7 ± 0.8 at baseline, P = 0.008). Guanethidine at 3 mg/kg iv was able to partially block the effects. (2) RD and CD reduced the percentage of normal intestinal slow waves from 92.1 ± 2.8 to 64.2 ± 3.4 % (P < 0.001) and from 90 ± 2.7 to 69.2 ± 3.7 % (P = 0.01), respectively. Guanethidine could eliminate these inhibitory effects. (3) DD did not induce any changes in small intestinal contractions and slow waves (P > 0.05). (4) The spectral analysis of the heart rate variability showed that both RD and CD increased sympathetic activity (LF) and reduced vagal activity (HF) (P < 0.05). Isobaric RD and CD could inhibit postprandial intestinal motility and impair intestinal slow waves, which were mediated via the sympathetic pathway. However, DD at a site proximal to the measurement site did not seem to impair small intestinal contractions or slow waves.

  12. Photoacoustic Techniques for Trace Gas Sensing Based on Semiconductor Laser Sources

    PubMed Central

    Elia, Angela; Lugarà, Pietro Mario; Di Franco, Cinzia; Spagnolo, Vincenzo

    2009-01-01

    The paper provides an overview on the use of photoacoustic sensors based on semiconductor laser sources for the detection of trace gases. We review the results obtained using standard, differential and quartz enhanced photoacoustic techniques. PMID:22303143

  13. Laser Frequency Stabilization for Coherent Lidar Applications using Novel All-Fiber Gas Reference Cell Fabrication Technique

    NASA Technical Reports Server (NTRS)

    Meras, Patrick, Jr.; Poberezhskiy, Ilya Y.; Chang, Daniel H.; Levin, Jason; Spiers, Gary D.

    2008-01-01

    Compact hollow-core photonic crystal fiber (HC-PCF)gas frequency reference cell was constructed using a novel packaging technique that relies on torch-sealing a quartz filling tube connected to a mechanical splice between regular and hollow-core fibers. The use of this gas cell for laser frequency stabilization was demonstrated by locking a tunable diode laser to the center of the P9 line from the (nu)1+(nu)3 band of acetylene with RMS frequency error of 2.06 MHz over 2 hours. This effort was performed in support of a task to miniaturize the laser frequency stabilization subsystem of JPL/LMCT Laser Absorption Spectrometer (LAS) instrument.

  14. Chemical composition and the nutritive value of pistachio epicarp (in situ degradation and in vitro gas production techniques)

    PubMed Central

    Bakhshizadeh, Somayeh; Taghizadeh, Akbar; Janmohammadi, Hossein; Alijani, Sadegh

    2014-01-01

    The nutritive value of pistachio epicarp (PE) was evaluated by in situ and in vitro techniques. Chemical analysis indicated that PE was high in crude protein (11.30%) and low in neutral detergent fiber (26.20%). Total phenols, total tannins, condensed tannins and hydrolysable tannins contents in PE were 8.29%, 4.48%, 0.49% and 3.79%, respectively. Ruminal dry matter and crude protein degradation after 48 hr incubation were 75.21% and 82.52%, respectively. The gas production volume at 48 hr for PE was 122.47 mL g-1DM. As a whole, adding polyethylene glycol (PEG) to PE increased (p < 0.05) gas production volumes, organic matter digestibility and the metabolizable energy that illustrated inhibitory effect of phenolics on rumen microbial fermentation and the positive influence of PEG on digestion PE. The results showed that PE possessed potentials to being used as feed supplements. PMID:25568691

  15. Solid phase micro extraction - A new technique coupled with gas chromatograph for chloroethene analysis from aqueous samples

    SciTech Connect

    Xu, N.; Sewell, G.W.

    1996-10-01

    Once the chloroethenes (tetrachloroethene and trichloroethene) contamination occurs in the subsurface environment, they tend to retain and form a Pollution plum in the aquifer because of their recalcitrance to aerobic oxidation. Currently, the most promising bioremediation method for chlorinated compounds is through anaerobic reductive biotransformation, in which each chlorine is replaced by a hydrogen. To study the biodegradation process, it is essential to monitor tetrachloroethene and its degradation daughter products frequently. An analytical method has been modified for chloroethene analysis by gas chromatography. Solid Phase Micro Extraction technique has been used to extract aqueous sample onto a fiber and then to desorb the sample directly into a gas chromatograph injection port. The total run time is less than 17 minutes.

  16. Flat plate film cooling measurement using PSP and gas chromatograph techniques

    SciTech Connect

    Zhang, L.J.; Fox, M.

    1999-07-01

    The use of pressure sensitive paint (PSP) to measure film cooling effectiveness is demonstrated in a high speed wind tunnel using a flat plate. To validate this technology, gas chromatography was used to measure film cooling effectiveness from the same plate. Four (4) blowing ratios 0.5, 0.75, 1.0 and 1.5 were tested using the two methods. The flow stream turbulence effect was not studied and the free stream turbulence intensity was fixed at 4.0%. The PSP was calibrated at various temperatures as well as at various pressures before testing. The test results on the flat plate indicate that the PSP method of measuring film cooling effectiveness is far superior than the traditional gas chromatography method. The better spatial resolution and two dimensionality of the pressure sensitive paint method offers a great potential for its application in film cooling measurements.

  17. Measuring fuel contamination using high speed gas chromatography and cone penetration techniques

    SciTech Connect

    Farrington, S.P.; Bratton, W.L.; Akard, M.L.

    1995-10-01

    Decision processes during characterization and cleanup of hazardous waste sites are greatly retarded by the turnaround time and expense incurred through the use of conventional sampling and laboratory analyses. Furthermore, conventional soil and groundwater sampling procedures present many opportunities for loss of volatile organic compounds (VOC) by exposing sample media to the atmosphere during transfers between and among sampling devices and containers. While on-site analysis by conventional gas chromatography can reduce analytical turnaround time, time-consuming sample preparation procedures are still often required, and the potential for loss of VOC is not reduced. This report describes the development of a high speed gas chromatography and cone penetration testing system which can detect and measure subsurface fuel contamination in situ during the cone penetration process.

  18. Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment

    USGS Publications Warehouse

    Steinheimer, T.R.; Pereira, W.E.; Johnson, S.M.

    1981-01-01

    A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds was accomplished by capillary gas chromatography/mass spectrometry techniques. More than 50 compounds were identified; these include saturated hydrocarbons, olefins, aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, and oxygenated compounds such as aldehydes and ketones. The role of bed sediments as a source or sink for organic pollutants is discussed. ?? 1981.

  19. multiplex gas chromatography: A novel analytical technique for future planetary studies

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.; Carle, G. C.; Phillips, J. B.

    1986-01-01

    Determination of molecular species comprised of the biogenic elements in the atmospheres of planets and moons of the solar system is one the foremost requirements of the exobiologist studying chemical evolution and the origin of life. Multiplex chromatography is a technique where many samples are pseudo-randomly introduced to the chromatograph without regard to elution of preceding components. The resulting data are then reduced using mathematical techniques such as cross correlation or Fourier Transforms. To demonstrate the utility of this technique for future solar system exploration, chemical modulators were developed. Several advantages were realized from this technique in combination with these modulators: improvement in detection limits of several orders of magnitude, improvement in the analysis of complex mixtures by selectively modulating some of the components present in the sample, increase in the number of analyses that can be conducted in a given period of time, and reduction in the amount of expendables needed to run an analysis. In order to apply this technique in a real application, methane in ambient air was monitored continuously over a period of one week. By using ambient air as its own carrier all expendables beyond power were eliminated.

  20. A Remote Sensing Technique For Combustion Gas Temperature Measurement In Black Liquor Recovery Boilers

    NASA Astrophysics Data System (ADS)

    Charagundla, S. R.; Semerjian, H. G.

    1986-10-01

    A remote sensing technique, based on the principles of emission spectroscopy, is being developed for temperature measurements in black liquor recovery boilers. Several tests have been carried out, both in the laboratory and at a number of recovery boilers, to characterize the emission spectra in the wavelength range of 300 nm to 800 nm. These tests have pointed out the potential for temperature measurements using the line intensity ratio technique based on a pair of emission lines at 404.4 nm and 766.5 nm observed in the recovery boiler combustion zone; these emission lines are due to potassium, a common constituent found in all the black liquors. Accordingly, a fiber optics based four-color system has been developed. This in-situ, nonintrusive temperature measurement technique, together with some of the more recent results, is described in this paper.

  1. Innovative Techniques of Multiphase Flow in Pipeline System for Oil-Gas Gathering and Transportation with Energy-Saving and Emission-Reduction

    NASA Astrophysics Data System (ADS)

    Bai, Bofeng; Guo, Liejin; Zhang, Shaojun; Zhang, Ximin; Gu, Hanyang

    2010-03-01

    Multiphase flow measurement, desanding, dehumidification and heat furnace are critical techniques for the oil and gas gathering and transportation, which influnce intensively the energy-saving and emission-reduction in the petroleum industry. Some innovative techniques were developed for the first time by the present research team, including an online recognation instrument of multiphase flow regime, a water fraction instrument for multuphase flow, a coiled tube desanding separator with low pressure loss and high efficiency, a supersonic swirling natural gas dehumifier, and a vacuum phase-change boiler. With an integration of the above techniques, a new oil gas gathering and transpotation system was proposed, which reduced the establishment of one metering station and several transfer stations compared with the tranditional system. The oil and gas mixture transpotation in single pipes was realized. The improved techniques were applied in the oilfields in China and promoted the productivity of the oilfields by low energy consumption, low emissions, high efficiency and great security.

  2. Optoelectronic technique for the characterization of high concentration gas-solid suspension.

    PubMed

    Cutolo, A; Rendina, I; Arena, U; Marzocchella, A; Massimilla, L

    1990-03-20

    We describe a simple technique for measuring high (up to 0.16) time-averaged solids volumetric concentration in a two-phase flow. The technique is based on a properly modified version of the forward scattering of laser light. It is useful in a variety of practical configurations, and, in particular, it is instrumental in the diagnostics of particle flow in the free board of bubbling fluidized beds and in the circulating fluidized beds. A fallout of this work is the measurement of the extinction coefficient of the solid material tested.

  3. A Gas Dynamics Method Based on The Spectral Deferred Corrections (SDC) Time Integration Technique and The Piecewise Parabolic Method (PPM)

    SciTech Connect

    Samet Y. Kadioglu

    2011-12-01

    We present a computational gas dynamics method based on the Spectral Deferred Corrections (SDC) time integration technique and the Piecewise Parabolic Method (PPM) finite volume method. The PPM framework is used to define edge averaged quantities which are then used to evaluate numerical flux functions. The SDC technique is used to integrate solution in time. This kind of approach was first taken by Anita et al in [17]. However, [17] is problematic when it is implemented to certain shock problems. Here we propose significant improvements to [17]. The method is fourth order (both in space and time) for smooth flows, and provides highly resolved discontinuous solutions. We tested the method by solving variety of problems. Results indicate that the fourth order of accuracy in both space and time has been achieved when the flow is smooth. Results also demonstrate the shock capturing ability of the method.

  4. Pressure drops in a distensible model of end-to-side anastomosis in systemic-to-pulmonary shunts.

    PubMed

    Migliavacca, Francesco; Pennati, Giancarlo; Di Martino, Elena; Dubini, Gabriele; Pietrabissa, Riccardo

    2002-06-01

    The modified Blalock-Taussig shunt is a surgical procedure used as a palliation to treat complex congenital heart defects. It consists of an interposing prosthetic tube between the innominate/subclavian artery and the right pulmonary artery. Previous experience indicates that the pressure drop across the shunt is affected by the pulmonary pressure at the distal anastomosis combined with the distensibility of the anastomosis. In this study, a computational fluid-structure interaction approach is presented to investigate the haemodynamic behaviour. Steady-state fluid dynamics and structural analyses were carried out using commercial codes based on the finite element method (FIDAP and ABAQUS) coupled by means of a purposely-developed procedure to transfer boundary conditions. Both prosthetic tube and artery walls were characterised by non-linear material properties. Three different pulmonary pressures (2, 5 and 15 mmHg) and two volume flow rates (0.4 and 0.8 l/min) were investigated. Results indicate that the effects of distensibility at the distal anastomosis on the shunt pressure drop are relevant only when the distal anastomosis on the shunt pressure drop are relevant only when the distal anastomosis is not fully distended, which occurs when the pulmonary pressure is lower than 5 mmHg.

  5. A high-resolution numerical technique for inviscid gas-dynamic problems with weak solutions

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Warming, R. F.; Harten, A.

    1982-01-01

    The shock resolution of Harten's (1982) second-order explicit method for one-dimensional hyperbolic conservation laws is investigated for a two-dimensional gas-dynamic problem. The possible extension to a high resolution implicit method for both one- and two-dimensional problems is also investigated. Applications of Harten's method to the quasi-one-dimensional nozzle problem with two nozzle shapes (divergent and convergent-divergent) and the two-dimensional shock-reflection problem resulted in high shock resolution steady-state numerical solutions.

  6. Experiences with a new soil gas technique for detecting petroleum pollution

    SciTech Connect

    Mazac, O.; Landa, I.; Rohde, J.R.; Kelly, W.E.; Blaha, J.H.

    1996-12-31

    This paper presents field experiences obtained with a new technology for detecting petroleum pollution in soil and ground water based on in situ determination of hydrocarbon concentrations in soil air. Ecoprobe is a new soil gas device from RS-Dynamics in the Czech Republic. The rugged waterproof device is equipped with a built-in computer-controlled semiconductor sensor. Three case histories are presented that demonstrate the use of the equipment under typical conditions. Two case histories present the use of the device under typical field conditions; the third case history compares results from the Ecoprobe and a commercial photoionization detector (PID) device.

  7. Gas Chromatographic-Mass Spectrometric Analysis of Volatiles Obtained by Four Different Techniques from Salvia rosifolia Sm. and Evaluation for Biological Activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Volatile constituents from the aerial parts of Salvia rosifolia Sm. (Lamiaceae), endemic to Turkey, were obtained by four different isolation techniques and then analyzed by gas chromatography (GC/FID) and gas chromatography – mass spectrometry (GC/MS) methods. Also in scope of the present work, the...

  8. Non-destructive evaluation techniques, high temperature ceramic component parts for gas turbines

    NASA Technical Reports Server (NTRS)

    Reiter, H.; Hirsekorn, S.; Lottermoser, J.; Goebbels, K.

    1984-01-01

    This report concerns studies conducted on various tests undertaken on material without destroying the material. Tests included: microradiographic techniques, vibration analysis, high-frequency ultrasonic tests with the addition of evaluation of defects and structure through analysis of ultrasonic scattering data, microwave tests and analysis of sound emission.

  9. Investigation of solid polymer electrolyte gas sensor with different electrochemical techniques

    NASA Astrophysics Data System (ADS)

    Strzelczyk, A.; Jasinski, G.; Chachulski, B.

    2016-01-01

    In this work solid polymer electrolyte (SPE) amperometric sulphur dioxide sensor is investigated. Nafion was used as a membrane electrode and 1M sulphuric acid as an internal electrolyte. Sensor response to sulphur dioxide was measured. Besides traditional constant voltage amperometry also different electrochemical techniques were used. Results obtained by these methods are compared.

  10. Gas-phase NMR technique for studying the thermolysis of materials: thermal decomposition of ammonium perfluorooctanoate.

    PubMed

    Krusic, Paul J; Roe, D Christopher

    2004-07-01

    The kinetics of the thermal decomposition of ammonium perfluorooctanoate (APFO) has been studied by high-temperature gas-phase nuclear magnetic resonance spectroscopy over the temperature range 196-234 degrees C. We find that APFO cleanly decomposes by first-order kinetics to give the hydrofluorocarbon 1-H-perfluoroheptane and is completely decomposed (>99%) in a matter of minutes at the upper limit of this temperature range. Based on the temperature dependence of the measured rate constants, we find that the enthalpy and entropy of activation are DeltaH++ = 150 +/- 11 kJ mol(-1) and DeltaS++ = 3 +/- 23 J mol(-)(1) deg(-1). These activation parameters may be used to calculate the rate of APFO decomposition at the elevated temperatures (350-400 degrees C) at which fluoropolymers are processed; for example, at 350 degrees C the half-life for APFO is estimated to be less than 0.2 s. Our studies provide the fundamental parameters involved in the decomposition of the ammonium salt of perfluorooctanoic acid and indicate the utility of gas-phase NMR for thermolysis studies of a variety of materials that release compounds that are volatile at the temperature of decomposition and that contain an NMR-active nucleus.

  11. Realization of a multipath ultrasonic gas flowmeter based on transit-time technique.

    PubMed

    Chen, Qiang; Li, Weihua; Wu, Jiangtao

    2014-01-01

    A microcomputer-based ultrasonic gas flowmeter with transit-time method is presented. Modules of the flowmeter are designed systematically, including the acoustic path arrangement, ultrasound emission and reception module, transit-time measurement module, the software and so on. Four 200 kHz transducers forming two acoustic paths are used to send and receive ultrasound simultaneously. The synchronization of the transducers can eliminate the influence caused by the inherent switch time in simple chord flowmeter. The distribution of the acoustic paths on the mechanical apparatus follows the Tailored integration, which could reduce the inherent error by 2-3% compared with the Gaussian integration commonly used in the ultrasonic flowmeter now. This work also develops timing modules to determine the flight time of the acoustic signal. The timing mechanism is different from the traditional method. The timing circuit here adopts high capability chip TDC-GP2, with the typical resolution of 50 ps. The software of Labview is used to receive data from the circuit and calculate the gas flow value. Finally, the two paths flowmeter has been calibrated and validated on the test facilities for air flow in Shaanxi Institute of Measurement & Testing. PMID:23809902

  12. A technique to control mercury from flue gas: The Thief Process

    SciTech Connect

    O'Dowd, W.J.; Pennline, H.W.; Freeman, M.C.; Granite, E.J.; Hargis, R.A.; Lacher, C.J.; Karash, A.

    2006-12-01

    The Thief Process is a mercury removal process that may be applicable to a broad range of pulverized coal-fired combustion systems. This is one of several sorbent injection technologies under development by the U.S. Department of Energy for capturing mercury from coal-fired electric utility boilers. A unique feature of the Thief Process involves the production of a thermally activated sorbent in situ at the power plant. The sorbent is obtained by inserting a lance, or thief, into the combustor, in or near the flame, and extracting a mixture of partially combusted coal and gas. The partially combusted coal or sorbent has adsorptive properties suitable for the removal of vapor-phase mercury at flue gas temperatures that are typical downstream of a power plant preheater. One proposed scenario, similar to activated carbon injection (ACI), involves injecting the extracted sorbent into the downstream ductwork between the air preheater and the particulate collection device of the power plant. Initial laboratory-scale and pilot-scale testing, using an eastern bituminous coal, focused on the concept validation. Subsequent pilot-scale testing, using a Powder River Basin (PRB) coal, focused on the process development and optimization. The results of the experimental studies, as well as an independent experimental assessment, are detailed. In addition, the results of a preliminary economic analysis that documents the costs and the potential economic advantages of the Thief Process for mercury control are discussed.

  13. CdS QDs-chitosan microcapsules with stimuli-responsive property generated by gas-liquid microfluidic technique.

    PubMed

    Chen, Yanjun; Yao, Rongyi; Wang, Yifeng; Chen, Ming; Qiu, Tong; Zhang, Chaocan

    2015-01-01

    This article describes a straightforward gas-liquid microfluidic approach to generate uniform-sized chitosan microcapsules containing CdS quantum dots (QDs). CdS QDs are encapsulated into the liquid-core of the microcapsules. The sizes of the microcapsules can be conveniently controlled by gas flow rate. QDs-chitosan microcapsules show good fluorescent stability in water, and exhibit fluorescent responses to chemical environmental stimuli. α-Cyclodextrin (α-CD) causes the microcapsules to deform and even collapse. More interestingly, α-CD induces obvious changes on the fluorescent color of the microcapsules. However, β-cyclodextrin (β-CD) has little influence on the shape and fluorescent color of the microcapsules. Based on the results of scanning electron microscopy, the possible mechanism about the effects of α-CD on the chitosan microcapsules is analyzed. These stimuli-responsive microcapsules are low-cost and easy to be prepared by gas-liquid microfluidic technique, and can be applied as a potential micro-detector to chemicals, such as CDs.

  14. Isotopic and Geochemical Investigation of Two Distinct Mars Analog Environments Using Evolved Gas Techniques in Svalbard, Norway

    NASA Technical Reports Server (NTRS)

    Stern, Jennifer Claire; Mcadam, Amy Catherine; Ten Kate, Inge L.; Bish, David L.; Blake, David F.; Morris, Richard V.; Bowden, Roxane; Fogel, Marilyn L.; Glamoclija, Mihaela; Mahaffy, Paul R.; Steele, Andrew; Amundsen, Hans E. F.

    2013-01-01

    The 2010 Arctic Mars Analog Svalbard Expedition (AMASE) investigated two distinct geologic settings on Svalbard, using methodologies and techniques to be deployed on Mars Science Laboratory (MSL). AMASErelated research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions. The Sample Analysis at Mars (SAM) instrument suite on MSL includes pyrolysis ovens, a gas-processing manifold, a quadrupole mass spectrometer (QMS), several gas chromatography columns, and a Tunable Laser Spectrometer (TLS). An integral part of SAM development is the deployment of SAM-like instrumentation in the field. During AMASE 2010, two parts of SAM participated as stand-alone instruments. A Hiden Evolved Gas Analysis- Mass Spectrometer (EGA-QMS) system represented the EGA-QMS component of SAM, and a Picarro Cavity Ring Down Spectrometer (EGA-CRDS), represented the EGA-TLS component of SAM. A field analog of CheMin, the XRD/XRF on MSL, was also deployed as part of this field campaign. Carbon isotopic measurements of CO2 evolved during thermal decomposition of carbonates were used together with EGA-QMS geochemical data, mineral composition information and contextual observations made during sample collection to distinguish carbonates formation associated with chemosynthetic activity at a fossil methane seep from abiotic processes forming carbonates associated with subglacial basaltic eruptions. Carbon and oxygen isotopes of the basalt-hosted carbonates suggest cryogenic carbonate formation, though more research is necessary to clarify the history of these rocks.

  15. Studying gas-sheared liquid film in horizontal rectangular duct with LIF technique: droplets deposition and bubbles entrapment

    NASA Astrophysics Data System (ADS)

    Cherdantsev, Andrey; Hann, David; Azzopardi, Barry

    2014-11-01

    High-speed laser-induced fluorescence technique is applied to study gas-sheared liquid film in horizontal rectangular duct (width 161 mm). Instantaneous distributions of film thickness over an area of 50*20 mm are obtained with frequency 10 kHz and spatial resolution 40 μm. The technique is also able to detect droplets entrained from film surface and gas bubbles entrapped by the liquid film. We focus on deposition of droplets onto film surface and dynamics of bubbles. Three scenarios of droplet impact are observed: 1) formation of a cavern, which is similar to well-known process of normal droplet impact onto still liquid surface; 2) ``ploughing,'' when droplet is sinking over long distance; 3) ``bouncing,'' when droplet survives the impact. The first scenario is often accompanied by entrainment of secondary droplets; the second by entrapment of air bubbles. Numerous impact events are quantitatively analyzed. Parameters of the impacting droplet, the film surface before the impact, the evolution of surface perturbation due to impact and the outcome of the impact (droplets or bubbles) are measured. Space-time trajectories of individual bubbles have also been obtained, including velocity, size and concentration inside the disturbance waves and in the base film region. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  16. Component greenhouse gas fluxes and radiative balance from two deltaic marshes in Louisiana: Pairing chamber techniques and eddy covariance

    NASA Astrophysics Data System (ADS)

    Krauss, Ken W.; Holm, Guerry O.; Perez, Brian C.; McWhorter, David E.; Cormier, Nicole; Moss, Rebecca F.; Johnson, Darren J.; Neubauer, Scott C.; Raynie, Richard C.

    2016-06-01

    Coastal marshes take up atmospheric CO2 while emitting CO2, CH4, and N2O. This ability to sequester carbon (C) is much greater for wetlands on a per area basis than from most ecosystems, facilitating scientific, political, and economic interest in their value as greenhouse gas sinks. However, the greenhouse gas balance of Gulf of Mexico wetlands is particularly understudied. We describe the net ecosystem exchange (NEEc) of CO2 and CH4 using eddy covariance (EC) in comparison with fluxes of CO2, CH4, and N2O using chambers from brackish and freshwater marshes in Louisiana, USA. From EC, we found that 182 g C m-2 yr-1 was lost through NEEc from the brackish marsh. Of this, 11 g C m-2 yr-1 resulted from net CH4 emissions and the remaining 171 g C m-2 yr-1 resulted from net CO2 emissions. In contrast, -290 g C m2 yr-1 was taken up through NEEc by the freshwater marsh, with 47 g C m-2 yr-1 emitted as CH4 and -337 g C m-2 yr-1 taken up as CO2. From chambers, we discovered that neither site had large fluxes of N2O. Sustained-flux greenhouse gas accounting metrics indicated that both marshes had a positive (warming) radiative balance, with the brackish marsh having a substantially greater warming effect than the freshwater marsh. That net respiratory emissions of CO2 and CH4 as estimated through chamber techniques were 2-4 times different from emissions estimated through EC requires additional understanding of the artifacts created by different spatial and temporal sampling footprints between techniques.

  17. Bird interactions with offshore oil and gas platforms: review of impacts and monitoring techniques.

    PubMed

    Ronconi, Robert A; Allard, Karel A; Taylor, Philip D

    2015-01-01

    Thousands of oil and gas platforms are currently operating in offshore waters globally, and this industry is expected to expand in coming decades. Although the potential environmental impacts of offshore oil and gas activities are widely recognized, there is limited understanding of their impacts on migratory and resident birds. A literature review identified 24 studies and reports of bird-platform interactions, most being qualitative and half having been peer-reviewed. The most frequently observed effect, for seabirds and landbirds, is attraction and sometimes collisions associated with lights and flares; episodic events have caused the deaths of hundreds or even thousands of birds. Though typically unpredictable, anecdotally, it is known that poor weather, such as fog, precipitation and low cloud cover, can exacerbate the effect of nocturnal attraction to lights, especially when coincidental with bird migrations. Other effects include provision of foraging and roosting opportunities, increased exposure to oil and hazardous environments, increased exposure to predators, or repulsion from feeding sites. Current approaches to monitoring birds at offshore platforms have focused on observer-based methods which can offer species-level bird identification, quantify seasonal patterns of relative abundance and distribution, and document avian mortality events and underlying factors. Observer-based monitoring is time-intensive, limited in spatial and temporal coverage, and suffers without clear protocols and when not conducted by trained, independent observers. These difficulties are exacerbated because deleterious bird-platform interaction is episodic and likely requires the coincidence of multiple factors (e.g., darkness, cloud, fog, rain conditions, occurrence of birds in vicinity). Collectively, these considerations suggest a need to implement supplemental systems for monitoring bird activities around offshore platforms. Instrument-based approaches, such as radar

  18. A smog chamber comparison of a microfluidic derivatization measurement of gas-phase glyoxal and methylglyoxal with other analytical techniques

    NASA Astrophysics Data System (ADS)

    Pang, X.; Lewis, A. C.; Richard, A.; Baeza-Romero, M. T.; Adams, T. J.; Ball, S. M.; Daniels, M. J. S.; Goodall, I. C. A.; Monks, P. S.; Peppe, S.; Ródenas García, M.; Sánchez, P.; Muñoz, A.

    2013-06-01

    A microfluidic lab-on-a-chip derivatization technique has been developed to measure part per billion volume (ppbV) mixing ratios of gaseous glyoxal (GLY) and methylglyoxal (MGLY), and the method compared with other techniques in a smog chamber experiment. The method uses o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) as a derivatization reagent and a microfabricated planar glass micro-reactor comprising an inlet, gas and fluid splitting and combining channels, mixing junctions, and a heated capillary reaction microchannel. The enhanced phase contact area-to-volume ratio and the high heat transfer rate in the micro-reactor result in a fast and highly efficient derivatization reaction, generating an effluent stream ready for direct introduction to a gas chromatograph-mass spectrometer (GC-MS). A linear response for GLY was observed over a calibration range 0.7 to 400 ppbV, and for MGLY of 1.2 to 300 ppbV, when derivatized under optimal reaction conditions. The method detection limits (MDLs) were 80 pptV and 200 pptV for GLY and MGLY respectively, calculated as 3 times the standard deviation of the S/N of the blank sample chromatograms. These MDLs are below or close to typical concentrations in clean ambient air. The feasibility of the technique was assessed by applying the methodology under controlled conditions to quantify of α-dicarbonyls formed during the photo-oxidation of isoprene in a large scale outdoor atmospheric simulation chamber (EUPHORE). Good general agreement was seen between microfluidic measurements and Fourier Transform Infra Red (FTIR), Broad Band Cavity Enhanced Absorption Spectroscopy (BBCEAS) and a detailed photochemical chamber box modelling calculation for both GLY and MGLY. Less good agreement was found with Proton-Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) and Solid Phase Microextraction (SPME) derivatization methods for MGLY measurement.

  19. Pros, cons of techniques used to calculate oil, gas finding costs

    SciTech Connect

    Gaddis, D.; Brock, H.; Boynton, C. )

    1992-06-01

    A major problem facing the U.S. petroleum industry is the higher average finding costs that now exist within the U.S. compared with the average finding costs outside the U.S. It has been argued that federal lands and offshore areas need to be open for drilling in order to reduce average finding costs in the U.S. This article analyzes the strengths and weaknesses of conventional techniques for determining finding costs. Our goal is a finding costs measure that is a reliable indicator of future profitability.

  20. Challenges to Laser-Based Imaging Techniques in Gas Turbine Combustor Systems for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Locke, Randy J.; Anderson, Robert C.; Zaller, Michelle M.; Hicks, Yolanda R.

    1998-01-01

    Increasingly severe constraints on emissions, noise and fuel efficiency must be met by the next generation of commercial aircraft powerplants. At NASA Lewis Research Center (LeRC) a cooperative research effort with industry is underway to design and test combustors that will meet these requirements. To accomplish these tasks, it is necessary to gain both a detailed understanding of the combustion processes and a precise knowledge of combustor and combustor sub-component performance at close to actual conditions. To that end, researchers at LeRC are engaged in a comprehensive diagnostic investigation of high pressure reacting flowfields that duplicate conditions expected within the actual engine combustors. Unique, optically accessible flame-tubes and sector rig combustors, designed especially for these tests. afford the opportunity to probe these flowfields with the most advanced, laser-based optical diagnostic techniques. However, these same techniques, tested and proven on comparatively simple bench-top gaseous flame burners, encounter numerous restrictions and challenges when applied in these facilities. These include high pressures and temperatures, large flow rates, liquid fuels, remote testing, and carbon or other material deposits on combustor windows. Results are shown that document the success and versatility of these nonintrusive optical diagnostics despite the challenges to their implementation in realistic systems.

  1. A smog chamber comparison of a microfluidic derivatisation measurement of gas-phase glyoxal and methylglyoxal with other analytical techniques

    NASA Astrophysics Data System (ADS)

    Pang, xiaobing; Lewis, Alastair; Rickard, Andrew R.; Baeza-Romero, Maria Teresa; Adams, Thomas J.; Ball, Stephen M.; Goodall, Iain C. A.; Monks, Paul S.; Peppe, Salvatore; Ródenas García, Milagros; Sánchez, Pilar; Muñoz, Amalia

    2014-05-01

    A microfluidic lab-on-a-chip derivatisation technique has been developed to measure part per billion (ppbV) mixing ratios of gaseous glyoxal (GLY) and methylglyoxal (MGLY), and the method is compared with other techniques in a smog chamber experiment. The method uses o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) as a derivatisation reagent and a microfabricated planar glass micro-reactor comprising an inlet, gas and fluid splitting and combining channels, mixing junctions, and a heated capillary reaction microchannel. The enhanced phase contact area-to-volume ratio and the high heat transfer rate in the micro-reactor result in a fast and highly efficient derivatisation reaction, generating an effluent stream ready for direct introduction to a gas chromatograph-mass spectrometer (GC-MS). A linear response for GLY was observed over a calibration range 0.7 to 400 ppbV, and for MGLY of 1.2 to 300 ppbV, when derivatised under optimal reaction conditions. The analytical performance shows good accuracy (6.6 % for GLY and 7.5 % for MGLY), suitable precision (< 12.0 %) and method detection limits (MDLs) (75 pptV for GLY and 185 pptV for MGLY) with a time resolution of 30 minutes. These MDLs are below or close to typical concentrations of these compounds observed in ambient air. The microfluidic derivatisation technique would be appropriate for ambient α-dicarbonyl measurements in a range of field environments based on its performance in a large-scale outdoor atmospheric simulation chamber (EUPHORE). The feasibility of the technique was assessed by applying the methodology to quantify of α-dicarbonyls formed during the photo-oxidation of isoprene in the EUPHORE chamber. Good correlations were found between microfluidic measurements and Fourier Transform InfraRed spectroscopy (FTIR) with the correlation coefficient (r2) of 0.84, Broad Band Cavity Enhanced Absorption Spectroscopy (BBCEAS) (r2 = 0.75), solid phase micro extraction (SPME) (r2 = 0.89), and a

  2. Characterization of Atypical Off-Flavor Compounds in Natural Cork Stoppers by Multidimensional Gas Chromatographic Techniques.

    PubMed

    Slabizki, Petra; Fischer, Claus; Legrum, Charlotte; Schmarr, Hans-Georg

    2015-09-01

    Natural cork stoppers with sensory deviations other than the typical cork taint were subgrouped according to their sensory descriptions and compared with unaffected control cork stoppers. The assessment of purge and trap extracts obtained from corresponding cork soaks was performed by heart-cut multidimensional gas chromatography-olfactometry (MDGC-O). The identification of compounds responsible for atypical cork taint detected in MDGC-O was further supported with additional multidimensional GC analysis in combination with mass spectrometric detection. Geosmin and 2-methylisoborneol were mainly found in cork stoppers described as moldy and cellarlike; 3-isopropyl-2-methoxypyrazine and 3-isobutyl-2-methoxypyrazine were found in cork stoppers described with green attributes. Across all cork subgroups, the impact compound for typical cork taint, 2,4,6-trichloroanisole (TCA), was present and is therefore a good marker for cork taint in general. Another potent aroma compound, 3,5-dimethyl-2-methoxypyrazine (MDMP), was also detected in each subgroup, obviously playing an important role with regard to the atypical cork taint. Sensory deviations possibly affecting the wine could be generated by MDMP and its presence should thus be monitored in routine quality control.

  3. Investigation of a mercury speciation technique for flue gas desulfurization materials

    SciTech Connect

    Lee, J.Y.; Cho K.; Cheng L.; Keener, T.C.; Jegadeesan G.; Al-Abed, S.R.

    2009-08-15

    Most of the synthetic gypsum generated from wet flue gas desulfurization (FGD) scrubbers is currently being used for wallboard production. Because oxidized mercury is readily captured by the wet FGD scrubber, and coal-fired power plants equipped with wet scrubbers desire to benefit from the partial mercury control that these systems provide, some mercury is likely to be bound in with the FGD gypsum and wallboard. In this study, the feasibility of identifying mercury species in the FGD gypsum and wallboard samples was investigated using a large sample size thermal desorption method and samples from power plants in Pennsylvania. Potential candidates of pure mercury standards including mercuric chloride, mercurous chloride, mercury oxide, mercury sulfide, and mercuric sulfate were analyzed to compare their results with those obtained from FGD gypsum and dry wallboard samples. Although any of the thermal evolutionary curves obtained from these pure mercury standards did not exactly match with those of the FGD gypsum and wallboard samples, it was identified that Hg{sub 2}Cl{sub 2} and HgCl{sub 2} could be candidates. An additional chlorine analysis from the gypsum and wallboard samples indicated that the chlorine concentrations were approximately 2 orders of magnitude higher than the mercury concentrations, suggesting possible chlorine association with mercury. 21 refs., 5 figs., 3 tabs.

  4. Investigation of a mercury speciation technique for flue gas desulfurization materials.

    PubMed

    Lee, Joo-Youp; Cho, Kyungmin; Cheng, Lei; Keener, Tim C; Jegadeesan, Gautham; Al-Abed, Souhail R

    2009-08-01

    Most of the synthetic gypsum generated from wet flue gas desulfurization (FGD) scrubbers is currently being used for wallboard production. Because oxidized mercury is readily captured by the wet FGD scrubber, and coal-fired power plants equipped with wet scrubbers desire to benefit from the partial mercury control that these systems provide, some mercury is likely to be bound in with the FGD gypsum and wallboard. In this study, the feasibility of identifying mercury species in the FGD gypsum and wallboard samples was investigated using a large sample size thermal desorption method. Potential candidates of pure mercury standards including mercuric chloride (HgCl2), mercurous chloride (Hg2Cl2), mercury oxide (HgO), mercury sulfide (HgS), and mercuric sulfate (HgSO4) were analyzed to compare their results with those obtained from FGD gypsum and dry wallboard samples. Although any of the thermal evolutionary curves obtained from these pure mercury standards did not exactly match with those of the FGD gypsum and wallboard samples, it was identified that Hg2Cl2 and HgCl2 could be candidates. An additional chlorine analysis from the gypsum and wallboard samples indicated that the chlorine concentrations were approximately 2 orders of magnitude higher than the mercury concentrations, suggesting possible chlorine association with mercury.

  5. Structural, morphological and gas sensing study of zinc doped tin oxide nanoparticles synthesized via hydrothermal technique

    NASA Astrophysics Data System (ADS)

    Singh, Davender; Kundu, Virender Singh; Maan, A. S.

    2016-07-01

    The pure and Zn-doped SnO2 nanoparticles were prepared successfully by hydrothermal route on large scale having different doping concentration of zinc from 0 to 0.20%. The calcined nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) for structural and morphological studies. XRD analyses reveal that the nanoparticles of these doping concentrations are polycrystalline in nature and existed as tetragonal rutile structure, SEM study of images confirms the existence of very small, homogeneously distributed, and spherical nanoparticles. The particles size of the nanoparticles was calculated by Scherrer formula and was found in the range of 9-21 nm. The presence of dopant (i.e. zinc) and formation of Sn-O phase and hydrous nature of Zn-doped SnO2 nanoparticles are confirmed by EDX and FTIR study. The gas sensing properties of pure and Zn-doped SnO2 nanoparticles were investigated for various concentrations of methanol, ethanol and acetone at different operating temperatures and it has been found that with doping concentration of zinc (x = 0.20%) shows the maximum response 78% to methanol, 65% to ethanol and 62% to acetone respectively at different operating temperature within the measurement limit for a concentration of 100 ppm of each gases.

  6. Investigation of a mercury speciation technique for flue gas desulfurization materials.

    PubMed

    Lee, Joo-Youp; Cho, Kyungmin; Cheng, Lei; Keener, Tim C; Jegadeesan, Gautham; Al-Abed, Souhail R

    2009-08-01

    Most of the synthetic gypsum generated from wet flue gas desulfurization (FGD) scrubbers is currently being used for wallboard production. Because oxidized mercury is readily captured by the wet FGD scrubber, and coal-fired power plants equipped with wet scrubbers desire to benefit from the partial mercury control that these systems provide, some mercury is likely to be bound in with the FGD gypsum and wallboard. In this study, the feasibility of identifying mercury species in the FGD gypsum and wallboard samples was investigated using a large sample size thermal desorption method. Potential candidates of pure mercury standards including mercuric chloride (HgCl2), mercurous chloride (Hg2Cl2), mercury oxide (HgO), mercury sulfide (HgS), and mercuric sulfate (HgSO4) were analyzed to compare their results with those obtained from FGD gypsum and dry wallboard samples. Although any of the thermal evolutionary curves obtained from these pure mercury standards did not exactly match with those of the FGD gypsum and wallboard samples, it was identified that Hg2Cl2 and HgCl2 could be candidates. An additional chlorine analysis from the gypsum and wallboard samples indicated that the chlorine concentrations were approximately 2 orders of magnitude higher than the mercury concentrations, suggesting possible chlorine association with mercury. PMID:19728491

  7. Measuring emissions from oil and natural gas well pads using the mobile flux plane technique.

    PubMed

    Rella, Chris W; Tsai, Tracy R; Botkin, Connor G; Crosson, Eric R; Steele, David

    2015-04-01

    We present a study of methane emissions from oil and gas producing well pad facilities in the Barnett Shale region of Texas, measured using an innovative ground-based mobile flux plane (MFP) measurement system, as part of the Barnett Coordinated Campaign.1 Using only public roads, we measured the emissions from nearly 200 well pads over 2 weeks in October 2013. The population of measured well pads is split into well pads with detectable emissions (N = 115) and those with emissions below the detection limit of the MFP instrument (N = 67). For those well pads with nonzero emissions, the distribution was highly skewed, with a geometric mean of 0.63 kg/h, a geometric standard deviation of 4.2, and an arithmetic mean of 1.72 kg/h. Including the population of nonemitting well pads, we find that the arithmetic mean of the well pads sampled in this study is 1.1 kg/h. This distribution implies that 50% of the emissions is due to the 6.6% highest emitting well pads, and 80% of the emissions is from the 22% highest emitting well pads.

  8. Techniques for obtaining detailed heat transfer coefficient measurements within gas turbine blade and vane cooling passages

    NASA Astrophysics Data System (ADS)

    Clifford, R. J.; Jones, T. V.; Dunnne, S. T.

    1983-03-01

    Techniques developed jointly by Rolls-Royce Bristol and Oxford University for determining detailed heat transfer distributions inside turbine blade and vane cooling passages are reviewed. Use is made of a low temperature phase change paint to map the heat flux distributions within models of the cooling passages; the paints change from an opaque coating to a clear liquid at a well-defined melting point. In this way the surface temperature history of a model subjected to transient convective heating is recorded. The heat transfer coefficient distribution is deduced from this history using a transient conduction analysis within the model. Results are presented on detailed heat transfer coefficient distributions within a variety of cooling passages; and data obtained from a comprehensive study of a typical engine multipass cooling geometry are examined.

  9. Determination of Synthetic Cathinones in Urine Using Gas Chromatography-Mass Spectrometry Techniques.

    PubMed

    Hong, Wei-Yin; Ko, Ya-Chun; Lin, Mei-Chih; Wang, Po-Yu; Chen, Yu-Pen; Chiueh, Lih-Ching; Shih, Daniel Yang-Chih; Chou, Hsiu-Kuan; Cheng, Hwei-Fang

    2016-01-01

    In recent years, the abuse of synthetic cathinones has increased considerably. This study proposes a method, based on gas chromatography/mass spectrometry (GC-MS), to analyze and quantify six synthetic cathinones in urine samples: mephedrone (4-MMC), methylone (bk-MDMA), butylone, ethylone, pentylone and methylenedioxypyrovalerone (MDPV). In our procedure, the urine samples undergo solid-phase extraction (SPE) and derivatization prior to injection into the GC-MS device. Separation is performed using a HP-5MS capillary column. The use of selective ion monitoring (SIM mode) makes it is good sensitivity in this method, and the entire analysis process is within 18 min. In addition, the proposed method maintains linearity in the calibration curve from 50 to 2,000 ng/mL (r(2) > 0.995). The limit of detection of this method is 5 ng/mL, with the exception of MDPV (20 ng/mL); the limit of quantification is 20 ng/mL, with the exception of MDPV (50 ng/mL). In testing, the extraction performance of SPE was between 82.34 and 104.46%. Precision and accuracy results were satisfactory <15%. The proposed method was applied to six real urine samples, one of which was found to contain 4-MMC and bk-MDMA. Our results demonstrate the efficacy of the proposed method in the identification of synthetic cathinones in urine, with regard to the limits of detection and quantification. This method is highly repeatable and accurate. PMID:26410364

  10. A comparison of rigid registration methods for prostate localization on CBCT and the dependence on rectum distension

    NASA Astrophysics Data System (ADS)

    Boydev, C.; Pasquier, D.; Derraz, F.; Peyrodie, L.; Taleb-Ahmed, A.; Thiran, J. P.

    2014-03-01

    We evaluated automatic three-dimensional intensity-based rigid registration (RR) methods for prostate localization on CBCT scans and studied the impact of rectum distension on registration quality. 106 CBCT scans of 9 prostate patients were used. Each one was registered to the planning computed tomography (CT) scan using different methods: (a) global registration, (b) pelvis bony structure registration, (c) bony registration refined by a local prostate registration using the CT clinical target volume (CTV) expanded with 1, 3, 5, 8, 10, 12, 15 or 20-mm margin. Automatic CBCT contours were generated after propagation of the manual CT contours. To evaluate results, a radiation oncologist was asked to manually delineate the CTV on the CBCT scans (gold standard). The Dice similarity coefficients between propagated and manual CBCT contours were calculated.

  11. Comparison of Techniques for Non-Intrusive Fuel Drop Size Measurements in a Subscale Gas Turbine Combustor

    NASA Technical Reports Server (NTRS)

    Zaller, Michelle; Anderson, Robert C.; Hicks, Yolanda R.; Locke, Randy J.

    1999-01-01

    In aviation gas turbine combustors, many factors, such as the degree and extent of fuel/air mixing and fuel vaporization achieved prior to combustion, influence the formation of undesirable pollutants. To assist in analyzing the extent of fuel/air mixing, flow visualization techniques have been used to interrogate the fuel distributions during subcomponent tests of lean-burning fuel injectors. Discrimination between liquid and vapor phases of the fuel was determined by comparing planar laser-induced fluorescence (PLIF) images, elastically-scattered light images, and phase/Doppler interferometer measurements. Estimates of Sauter mean diameters are made by ratioing PLIF and Mie scattered intensities for various sprays, and factors affecting the accuracy of these estimates are discussed. Mie calculations of absorption coefficients indicate that the fluorescence intensities of individual droplets are proportional to their surface areas, instead of their volumes, due to the high absorbance of the liquid fuel for the selected excitation wavelengths.

  12. Advanced analytical techniques for the extraction and characterization of plant-derived essential oils by gas chromatography with mass spectrometry.

    PubMed

    Waseem, Rabia; Low, Kah Hin

    2015-02-01

    In recent years, essential oils have received a growing interest because of the positive health effects of their novel characteristics such as antibacterial, antifungal, and antioxidant activities. For the extraction of plant-derived essential oils, there is the need of advanced analytical techniques and innovative methodologies. An exhaustive study of hydrodistillation, supercritical fluid extraction, ultrasound- and microwave-assisted extraction, solid-phase microextraction, pressurized liquid extraction, pressurized hot water extraction, liquid-liquid extraction, liquid-phase microextraction, matrix solid-phase dispersion, and gas chromatography (one- and two-dimensional) hyphenated with mass spectrometry for the extraction through various plant species and analysis of essential oils has been provided in this review. Essential oils are composed of mainly terpenes and terpenoids with low-molecular-weight aromatic and aliphatic constituents that are particularly important for public health.

  13. Sn and Cu oxide nanoparticles deposited on TiO2 nanoflower 3D substrates by Inert Gas Condensation technique

    NASA Astrophysics Data System (ADS)

    Kusior, A.; Kollbek, K.; Kowalski, K.; Borysiewicz, M.; Wojciechowski, T.; Adamczyk, A.; Trenczek-Zajac, A.; Radecka, M.; Zakrzewska, K.

    2016-09-01

    Sn and Cu oxide nanoparticles were deposited by Inert Gas Condensation (IGC) technique combined with dc magnetron sputtering onto nanoflower TiO2 3D substrates obtained in the oxidation process of Ti-foil in 30% H2O2. Sputtering parameters such as insertion length and Ar/He flow rates were optimized taking into account the nanostructure morphology. Comparative studies with hydrothermal method were carried out. Surface properties of the synthesized nanomaterials were studied by Scanning Electron Microscopy, SEM, Atomic Force Microscopy, AFM, and X-ray Photoelectron Spectroscopy, XPS. X-ray diffraction, XRD and Raman spectroscopy were performed in order to determine phase composition. Impedance spectroscopy demonstrated the influence of nanoparticles on the electrical conductivity.

  14. Fuel Injector Patternation Evaluation in Advanced Liquid-Fueled, High Pressure, Gas Turbine Combustors, Using Nonintrusive Optical Diagnostic Techniques

    NASA Technical Reports Server (NTRS)

    Locke, R. J.; Hicks, Y. R.; Anderson, R. C.; Zaller, M. M.

    1998-01-01

    Planar laser-induced fluorescence (PLIF) imaging and planar Mie scattering are used to examine the fuel distribution pattern (patternation) for advanced fuel injector concepts in kerosene burning, high pressure gas turbine combustors. Three diverse fuel injector concepts for aerospace applications were investigated under a broad range of operating conditions. Fuel PLIF patternation results are contrasted with those obtained by planar Mie scattering. Further comparison is also made for one injector with data obtained through phase Doppler measurements. Differences in spray patterns for diverse conditions and fuel injector configurations are readily discernible. An examination of the data has shown that a direct determination of the fuel spray angle at realistic conditions is also possible. The results obtained in this study demonstrate the applicability and usefulness of these nonintrusive optical techniques for investigating fuel spray patternation under actual combustor conditions.

  15. Ambient Atmospheric Hydrocarbon Content as Determined by Gas Chromatographic Techniques from Rural Tidewater Virginia in Late Spring 1974

    NASA Technical Reports Server (NTRS)

    Copeland, G. E.; Davis, R.; Maroulis, P.; Bandy, A. R.; Denyszyn, R.; Kindle, E. C.

    1975-01-01

    In an attempt to ascertain the naturally generated hydrocarbon contribution to the air quality of the Hampton Roads region of Tidewater Virginia, a series of 27 air samples was obtained in two rural locations during late spring of 1974. These samples were analyzed for their hydrocarbon content (carbon number range C5 to C10) using gas chromatographic techniques. The thirty different hydrocarbon species were identified and monitored in the experiment. Preliminary analysis of the data indicates an average concentration of 397 parts per billion by weight (carbon) for the total non-methane hydrocarbon loading for C5 to C10 during the experiment. This value exceeds the National Primary Air Quality Standards as set by the Environmental Protection Agency.

  16. A smog chamber comparison of a microfluidic derivatisation measurement of gas-phase glyoxal and methylglyoxal with other analytical techniques

    NASA Astrophysics Data System (ADS)

    Pang, X.; Lewis, A. C.; Rickard, A. R.; Baeza-Romero, M. T.; Adams, T. J.; Ball, S. M.; Daniels, M. J. S.; Goodall, I. C. A.; Monks, P. S.; Peppe, S.; Ródenas García, M.; Sánchez, P.; Muñoz, A.

    2014-02-01

    A microfluidic lab-on-a-chip derivatisation technique has been developed to measure part per billion (ppbV) mixing ratios of gaseous glyoxal (GLY) and methylglyoxal (MGLY), and the method is compared with other techniques in a smog chamber experiment. The method uses o-(2, 3, 4, 5, 6-pentafluorobenzyl) hydroxylamine (PFBHA) as a derivatisation reagent and a microfabricated planar glass micro-reactor comprising an inlet, gas and fluid splitting and combining channels, mixing junctions, and a heated capillary reaction microchannel. The enhanced phase contact area-to-volume ratio and the high heat transfer rate in the micro-reactor resulted in a fast and highly efficient derivatisation reaction, generating an effluent stream ready for direct introduction to a gas chromatograph-mass spectrometer (GC-MS). A linear response for GLY was observed over a calibration range 0.7 to 400 ppbV, and for MGLY of 1.2 to 300 ppbV, when derivatised under optimal reaction conditions. The analytical performance shows good accuracy (6.6% for GLY and 7.5% for MGLY), suitable precision (<12.0%) with method detection limits (MDLs) of 75 pptV for GLY and 185 pptV for MGLY, with a time resolution of 30 min. These MDLs are below or close to typical concentrations of these compounds observed in ambient air. The feasibility of the technique was assessed by applying the methodology to quantify α-dicarbonyls formed during the photo-oxidation of isoprene in the EUPHORE chamber. Good correlations were found between microfluidic measurements and Fourier Transform InfraRed spectroscopy (FTIR) with a correlation coefficient (r2) of 0.84, Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS) (r2 = 0.75), solid phase micro extraction (SPME) (r2 = 0.89), and a photochemical chamber box modelling calculation (r2 = 0.79) for GLY measurements. For MGLY measurements, the microfluidic technique showed good agreement with BBCEAS (r2 = 0.87), SPME (r2 = 0.76), and the modeling simulation (r2 = 0.83), FTIR

  17. Delta13C analyses of calcium carbonate: Comparison between the GasBench and elemental analyzer techniques.

    PubMed

    Skrzypek, Grzegorz; Paul, Debajyoti

    2006-01-01

    Measurements of stable carbon isotopic composition (delta13C) of carbonates or carbonate-rich soils are seldom performed in a continuous-flow isotope ratio mass spectrometer (IRMS) using an elemental analyzer (EA) as an online sample preparation device. Such analyses are routinely carried out with an external precision better than 0.1 per thousand using a GasBench II (GB) sample preparation device coupled online with a continuous-flow IRMS. In this paper, we report and compare delta13C analyses (86 total analyses) of calcium carbonates obtained by using both the GB and the EA. Using both techniques, the delta13C compositions of two in-house carbonate standards (MERCK carbonate and NR calcite) and ten selected carbonate-rich paleosol samples (of variable CaCO3 content) were analyzed, and data are reported in the VPDB scale calibrated against international standards, NBS 18 and 19. For the in-house standards analyzed by both techniques, a precision better than 0.08 per thousand is achieved. The analytical errors (1sigma) computed from multiple analyses of the delta13C of both the MERCK and NR obtained by the above two techniques are nearly identical. In general, the 1sigma (internal error) of paleosol analyses obtained in the GB is better than 0.06 per thousand, whereas that for the analyses in the EA (three repetitive analyses of the same sample) varies in the range 0.05-0.21 per thousand. However, for paleosols having more than 85% CaCO3, 1sigma is better than 0.15 per thousand (similar to the instrument precision), and in this case the delta13C(VPDB) of samples obtained by the GB is similar to that obtained by the EA. Our results suggest that the delta13C of pure calcium carbonate samples can also be analyzed using the EA technique.

  18. Influence of Rain Tree Pod Meal Supplementation on Rice Straw Based Diets Using In vitro Gas Fermentation Technique.

    PubMed

    Anantasook, N; Wanapat, M

    2012-03-01

    The objective of this study was to determine the roughage to concentrate (R:C) ratio with rain tree pod meal (RPM) supplementation on in vitro fermentation using gas production technique. The experiment design was a 6×4 factorial arrangement in a CRD. Factor A was 6 levels of R:C ratio (100:0, 80:20, 60:40, 40:60, 20:80 and 0:100) and factor B was 4 levels of RPM (0, 4, 8 and 12 mg). It was found that gas kinetic, extent rate (c) was linearly increased (p<0.01) with an increasing level of concentrate while cumulative gas production (96 h) was higher in R:C of 40:60. In addition, interaction of R:C ratio and RPM level affected NH3-N and IVDMD and were highest in R:C of 0:100 with 0, 4 mg of RPM and 40:60 with 8 mg of RPM, respectively. Moreover, interaction of R:C ratio and RPM level significantly increased total volatile fatty acids and propionate concentration whereas lower acetate, acetate to propionate ratios and CH4 production in R:C of 20:80 with 8 mg of RPM. Moreover, the two factors, R:C ratio and RPM level influenced the protozoal population and the percentage of methanogens in the total bacteria population. In addition, the use of real-time PCR found that a high level of concentrate in the diet remarkably decreased three cellulolytic bacteria numbers (F. succinogenes, R. flavefaciens and R. albus). Based on this study, it is suggested that the ratio of R:C at 40:60 and RPM level at 12 mg could improve ruminal fluid fermentation in terms of reducing fermentation losses, thus improving VFA profiles and ruminal ecology.

  19. Diagnostics and Control of Natural Gas-Fired furnaces via Flame Image Analysis using Machine Vision & Artificial Intelligence Techniques

    SciTech Connect

    Shahla Keyvan

    2005-12-01

    A new approach for the detection of real-time properties of flames is used in this project to develop improved diagnostics and controls for natural gas fired furnaces. The system utilizes video images along with advanced image analysis and artificial intelligence techniques to provide virtual sensors in a stand-alone expert shell environment. One of the sensors is a flame sensor encompassing a flame detector and a flame analyzer to provide combustion status. The flame detector can identify any burner that has not fired in a multi-burner furnace. Another sensor is a 3-D temperature profiler. One important aspect of combustion control is product quality. The 3-D temperature profiler of this on-line system is intended to provide a tool for a better temperature control in a furnace to improve product quality. In summary, this on-line diagnostic and control system offers great potential for improving furnace thermal efficiency, lowering NOx and carbon monoxide emissions, and improving product quality. The system is applicable in natural gas-fired furnaces in the glass industry and reheating furnaces used in steel and forging industries.

  20. Correction of Dynamic Errors of a Gas Sensor Based on a Parametric Method and a Neural Network Technique

    PubMed Central

    Roj, Jerzy

    2016-01-01

    The paper presents two methods of dynamic error correction applied to transducers used for the measurement of gas concentration. One of them is based on a parametric model of the transducer dynamics, and the second one uses the artificial neural network (ANN) technique. This article describes research of the dynamic properties of the gas concentration measuring transducer with a typical sensor based on tin dioxide. Its response time is about 8 min, which may be not acceptable in many applications. On the basis of these studies, a parametric model of the transducer dynamics and an adequate correction algorithm has been developed. The results obtained in the research of the transducer were also used for learning and testing ANN, which were implemented in the dynamic correction task. Despite the simplicity of the used models, both methods allowed a significant reduction of the transducer’s response time. For the algorithm based on the parametric model the response time was shorter by approximately eight-fold (reduced up to 40–80 s, i.e., about 2–4 sample periods), whereas with the use of an ANN the output signal was practically fixed after a time equal to one sampling period, i.e., 20 s. In addition, the use of ANN has allowed reducing the impact of the transducer dynamic non-linearity on the correction effectiveness. PMID:27517933

  1. Characterization of thermal desorption with the Deans-switch technique in gas chromatographic analysis of volatile organic compounds.

    PubMed

    Ou-Yang, Chang-Feng; Huang, Ying-Xue; Huang, Ting-Jyun; Chen, Yong-Shen; Wang, Chieh-Heng; Wang, Jia-Lin

    2016-09-01

    This study presents a novel application based on the Deans-switch cutting technique to characterize the thermal-desorption (TD) properties for gas chromatographic (GC) analysis of ambient volatile organic compounds (VOCs). Flash-heating of the sorbent bed at high temperatures to desorb trapped VOCs to GC may easily produce severe asymmetric or tailing GC peaks affecting resolution and sensitivity if care is not taken to optimize the TD conditions. The TD peak without GC separation was first examined for the quality of the TD peak by analyzing a standard gas mixture from C2 to C12 at ppb level. The Deans switch was later applied in two different stages. First, it was used to cut the trailing tail of the TD peak, which, although significantly improved the GC peak symmetry, led to more loss of the higher boiling compounds than the low boiling ones, thus suggesting compound discrimination. Subsequently, the Deans switch was used to dissect the TD peak into six 30s slices in series, and an uneven distribution in composition between the slices were found. A progressive decrease in low boiling compounds and increase in higher boiling ones across the slices indicated severe inhomogeneity in the TD profile. This finding provided a clear evidence to answer the discrimination problem found with the tail cutting approach to improve peak symmetry. Through the use of the innovated slicing method based on the Deans-switch cutting technique, optimization of TD injection for highly resolved, symmetric and non-discriminated GC peaks can now be more quantitatively assessed and guided. PMID:27492597

  2. Characterization of thermal desorption with the Deans-switch technique in gas chromatographic analysis of volatile organic compounds.

    PubMed

    Ou-Yang, Chang-Feng; Huang, Ying-Xue; Huang, Ting-Jyun; Chen, Yong-Shen; Wang, Chieh-Heng; Wang, Jia-Lin

    2016-09-01

    This study presents a novel application based on the Deans-switch cutting technique to characterize the thermal-desorption (TD) properties for gas chromatographic (GC) analysis of ambient volatile organic compounds (VOCs). Flash-heating of the sorbent bed at high temperatures to desorb trapped VOCs to GC may easily produce severe asymmetric or tailing GC peaks affecting resolution and sensitivity if care is not taken to optimize the TD conditions. The TD peak without GC separation was first examined for the quality of the TD peak by analyzing a standard gas mixture from C2 to C12 at ppb level. The Deans switch was later applied in two different stages. First, it was used to cut the trailing tail of the TD peak, which, although significantly improved the GC peak symmetry, led to more loss of the higher boiling compounds than the low boiling ones, thus suggesting compound discrimination. Subsequently, the Deans switch was used to dissect the TD peak into six 30s slices in series, and an uneven distribution in composition between the slices were found. A progressive decrease in low boiling compounds and increase in higher boiling ones across the slices indicated severe inhomogeneity in the TD profile. This finding provided a clear evidence to answer the discrimination problem found with the tail cutting approach to improve peak symmetry. Through the use of the innovated slicing method based on the Deans-switch cutting technique, optimization of TD injection for highly resolved, symmetric and non-discriminated GC peaks can now be more quantitatively assessed and guided.

  3. Effect of fedotozine on the cardiovascular pain reflex induced by distension of the irritated colon in the anesthetized rat.

    PubMed

    Langlois, A; Diop, L; Rivière, P J; Pascaud, X; Junien, J L

    1994-12-27

    The effect of fedotozine was evaluated in a model of colonic hypersensibility to balloon distension in anesthetized rats. Acetic acid (0.6%, intracolonically) significantly enhanced the hypotension reflex response to colonic distension (P < 0.05). At a noxious pain pressure (75 mm Hg), fedotozine ((+)-(-1R)-1-phenyl-1-[(3,4,5- trimethoxy)benzyloxymethyl]-N,N-dimethyl-n-propylamine) had no effect at 0.6 and 1 mg/kg i.v. in saline-treated rats and higher doses were required to produce antinociception (ED50 = 2.57 mg/kg i.v.). By contrast, fedotozine at 0.6 and 1 mg/kg i.v. displayed 38 and 54% antinociception (P < 0.05) respectively, in acetic acid-treated animals, leading to a decrease in its ED50 (1.15 mg/kg i.v.). Similar results were obtained with (+/-)-trans-N-methyl-N-[2-(pyrrolidinyl)-cyclohexyl]benzo[b]-thiophene- 4-acetamide (PD-117,302), a kappa-opioid receptor agonist, while the antinociceptive action of morphine and a kappa-opioid receptor agonist, trans-(+/-)-3,4-dichloro-N-methyl-N-(2-[1- pyrrolidinyl]cyclohexyl)benzenacetamide ((+/-)-U-50,488H), was identical in control and acetic acid-treated animals. Nor-binaltorphimine, a selective kappa-opioid receptor antagonist, reversed the enhanced antinociceptive activity of fedotozine and PD-117,302. It is concluded that acetic acid induces colonic hypersensibility to painful mechanical stimuli and that some but not all kappa-opioid receptor ligands can have enhanced efficacy in this pathological situation. PMID:7705424

  4. Removal Dynamics of Nitric Oxide (NO) Pollutant Gas by Pulse-Discharged Plasma Technique

    PubMed Central

    Zhang, Lianshui; Wang, Xiaojun; Lai, Weidong; Cheng, Xueliang; Zhao, Kuifang

    2014-01-01

    Nonthermal plasma technique has drawn extensive attentions for removal of air pollutants such as NOx and SO2. The NO removal mechanism in pulse discharged plasma is discussed in this paper. Emission spectra diagnosis indicates that the higher the discharge voltage is, the more the NO are removed and transformed into O, N, N2, NO2, and so forth. Plasma electron temperature Te is ranged from 6400 K at 2.4 kV discharge voltage to 9500 K at 4.8 kV. After establishing a zero-dimensional chemical reaction kinetic model, the major reaction paths are clarified as the electron collision dissociation of NO into N and O during discharge and followed by single substitution of N on NO to form N2 during and after discharge, compared with the small fraction of NO2 formed by oxidizing NO. The reaction directions can be adjusted by N2 additive, and the optimal N2/NO mixing ratio is 2 : 1. Such a ratio not only compensates the disadvantage of electron competitive consumption by the mixed N2, but also heightens the total NO removal extent through accelerating the NO oxidization process. PMID:24737985

  5. [Artificial humidification of inspired gas--status of knowledge and technique].

    PubMed

    Henze, D; Menzel, M; Radke, J

    1997-01-01

    Artificial humidification of inspired air serves to maintain or restore physiological heat and moisture conditions in the bronchial system in intubated or tracheotomized patients. The need to condition the respiratory gases in these patients is undisputed. The present paper reviews the pathophysiology and methods of the artificial active and passive humidifying of inspired gases. The various advantages and disadvantages of the individual methods and techniques of humidifying inspired gases are compared and discussed. Present-day medical knowledge indicates that passive artificial humidifying of respiratory gases (heat and moisture exchanger, HME) is adequate to meet most requirements for warming and moistening the inspiratory air in patients whose upper airways are devoid of natural conditioning of respiratory gases in consequence of intubation and tracheotomy. This applies to artificial ventilation in prehospital situations, artificial ventilation in anaesthesia and long-term artificial ventilation on the intensive care unit. With appropriate restrictions, the respiratory air of patients who breathe spontaneously via an artificial air vent (e.g. tracheal cannula) can also be conditioned by HME.

  6. Use of Immunohistochemistry Techniques in Patients Exposed to Sulphur Mustard Gas

    PubMed Central

    Ghanei, Mostafa; Chilosi, Marco; Mohammad Hosseini Akbari, Hassan; Motiei-Langroudi, Rouzbeh; Harandi, Ali Amini; Shamsaei, Hassan; Bahadori, Moslem; Tazelaar, Henry D.

    2011-01-01

    We performed a pathologic study with further using an immunohistochemical technique (using anti-p63 and anti-CK5) on tissues obtained by open lung biopsy from 18 patients with previous exposure to sulphur mustard (SM) as case group and 8 unexposed patients (control group). The most frequent pathologic diagnosis was constrictive bronchiolitis (44.4%), followed by respiratory (22.2%) and chronic cellular bronchiolitis (16.7%) in the case group, and hypersensitivity bronchiolitis (50%) in the control group. The pathologic diagnoses were significantly different in the case and control groups (P = 0.042). In slides stained by anti-p63 and anti-CK5, the percent of stained cells and the mean number of epithelial cells were lower in the case group in comparison to the control group. This difference was significant for the mean number of cells stained by anti-CK5 (P = 0.042). Furthermore, there was a significant correlation between pathologic diagnosis and total number of cells and mean number of cells stained with anti-p63 and anti-CK5 (P  value = 0.002, <0.001, 0.044). These results suggest that constrictive bronchiolitis may be the major pathologic consequence of exposure to SM. Moreover, decrease of p63 in respiratory tissues affected by SM may suggest the lack of regenerative capacity in these patients. PMID:21776342

  7. Use of immunohistochemistry techniques in patients exposed to sulphur mustard gas.

    PubMed

    Ghanei, Mostafa; Chilosi, Marco; Mohammad Hosseini Akbari, Hassan; Motiei-Langroudi, Rouzbeh; Harandi, Ali Amini; Shamsaei, Hassan; Bahadori, Moslem; Tazelaar, Henry D

    2011-01-01

    We performed a pathologic study with further using an immunohistochemical technique (using anti-p63 and anti-CK5) on tissues obtained by open lung biopsy from 18 patients with previous exposure to sulphur mustard (SM) as case group and 8 unexposed patients (control group). The most frequent pathologic diagnosis was constrictive bronchiolitis (44.4%), followed by respiratory (22.2%) and chronic cellular bronchiolitis (16.7%) in the case group, and hypersensitivity bronchiolitis (50%) in the control group. The pathologic diagnoses were significantly different in the case and control groups (P = 0.042). In slides stained by anti-p63 and anti-CK5, the percent of stained cells and the mean number of epithelial cells were lower in the case group in comparison to the control group. This difference was significant for the mean number of cells stained by anti-CK5 (P = 0.042). Furthermore, there was a significant correlation between pathologic diagnosis and total number of cells and mean number of cells stained with anti-p63 and anti-CK5 (P  value = 0.002, <0.001, 0.044). These results suggest that constrictive bronchiolitis may be the major pathologic consequence of exposure to SM. Moreover, decrease of p63 in respiratory tissues affected by SM may suggest the lack of regenerative capacity in these patients. PMID:21776342

  8. Component greenhouse gas fluxes and radiative balance from two deltaic marshes in Louisiana: Pairing chamber techniques and eddy covariance

    USGS Publications Warehouse

    Krauss, Ken W.; Holm, Guerry O.; Perez, Brian C.; McWhorter, David E.; Cormier, Nicole; Moss, Rebecca; Johnson, Darren; Neubauer, Scott C; Raynie, Richard C

    2016-01-01

    Coastal marshes take up atmospheric CO2 while emitting CO2, CH4, and N2O. This ability to sequester carbon (C) is much greater for wetlands on a per-area basis than from most ecosystems, facilitating scientific, political, and economic interest in their value as greenhouse gas sinks. However, the greenhouse gas balance of Gulf of Mexico wetlands is particularly understudied. We describe the net ecosystem exchange (NEEc) of CO2 and CH4 using eddy covariance (EC) in comparison with fluxes of CO2, CH4, and N2O using chambers from brackish and freshwater marshes in Louisiana, USA. From EC, we found that 182 g C m-2 y-1 was lost through NEEc from the brackish marsh. Of this, 11 g C m-2 y-1 resulted from net CH4 emissions and the remaining 171 g C m-2 y-1 resulted from net CO2 emissions. In contrast, -290 g C m2 y-1 was taken up through NEEc by the freshwater marsh, with 47 g C m-2 y-1 emitted as CH4 and -337 g C m-2 y-1 taken up as CO2. From chambers, we discovered that neither site had large fluxes of N2O. Sustained-flux greenhouse gas accounting metrics indicated that both marshes had a positive (warming) radiative balance, with the brackish marsh having a substantially greater warming effect than the freshwater marsh. That net respiratory emissions of CO2 and CH4 as estimated through chamber techniques were 2-4 times different from emissions estimated through EC requires additional understanding of the artifacts created by different spatial and temporal sampling footprints between techniques.

  9. CHARACTERIZATION OF CONDITIONS OF NATURAL GAS STORAGE RESERVOIRS AND DESIGN AND DEMONSTRATION OF REMEDIAL TECHNIQUES FOR DAMAGE MECHANISMS FOUND THEREIN

    SciTech Connect

    J.H. Frantz Jr; K.G. Brown; W.K. Sawyer; P.A. Zyglowicz; P.M. Halleck; J.P. Spivey

    2004-12-01

    The underground gas storage (UGS) industry uses over 400 reservoirs and 17,000 wells to store and withdrawal gas. As such, it is a significant contributor to gas supply in the United States. It has been demonstrated that many UGS wells show a loss of deliverability each year due to numerous damage mechanisms. Previous studies estimate that up to one hundred million dollars are spent each year to recover or replace a deliverability loss of approximately 3.2 Bscf/D per year in the storage industry. Clearly, there is a great potential for developing technology to prevent, mitigate, or eliminate the damage causing deliverability losses in UGS wells. Prior studies have also identified the presence of several potential damage mechanisms in storage wells, developed damage diagnostic procedures, and discussed, in general terms, the possible reactions that need to occur to create the damage. However, few studies address how to prevent or mitigate specific damage types, and/or how to eliminate the damage from occurring in the future. This study seeks to increase our understanding of two specific damage mechanisms, inorganic precipitates (specifically siderite), and non-darcy damage, and thus serves to expand prior efforts as well as complement ongoing gas storage projects. Specifically, this study has resulted in: (1) An effective lab protocol designed to assess the extent of damage due to inorganic precipitates; (2) An increased understanding of how inorganic precipitates (specifically siderite) develop; (3) Identification of potential sources of chemical components necessary for siderite formation; (4) A remediation technique that has successfully restored deliverability to storage wells damaged by the inorganic precipitate siderite (one well had nearly a tenfold increase in deliverability); (5) Identification of the types of treatments that have historically been successful at reducing the amount of non-darcy pressure drop in a well, and (6) Development of a tool that can

  10. Technique of estimation of actual strength of a gas pipeline section at its deformation in landslide action zone

    SciTech Connect

    Tcherni, V.P.

    1996-12-31

    The technique is given which permits determination of stress and strain state (SSS) and estimation of actual strength of a section of a buried main gas pipeline (GP) in the case of its deformation in a landslide action zone. The technique is based on the use of three-dimensional coordinates of axial points of the deformed GP section. These coordinates are received by a full-scale survey. The deformed axis of the surveyed GP section is described by the polynomial. The unknown coefficients of the polynomial can be determined from the boundary conditions at points of connection with contiguous undeformed sections as well as by use of minimization methods in mathematical processing of full-scale survey results. The resulting form of GP section`s axis allows one to determine curvatures and, accordingly, bending moments along all the length of the considered section. The influence of soil resistance to longitudinal displacements of a pipeline is used to determine longitudinal forces. Resulting values of bending moments and axial forces as well as the known value of internal pressure are used to analyze all necessary components of an actual SSS of pipeline section and to estimate its strength by elastic analysis.

  11. Characterization of an array of Love-wave gas sensors developed using electrospinning technique to deposit nanofibers as sensitive layers.

    PubMed

    Matatagui, D; Fernández, M J; Fontecha, J; Sayago, I; Gràcia, I; Cané, C; Horrillo, M C; Santos, J P

    2014-03-01

    The electrospinning technique has allowed that very different materials are deposited as sensitive layers on Love-wave devices forming a low cost and successful sensor array. Their excellent sensitivity, good linearity and short response time are reported in this paper. Several materials have been used to produce the nanofibers: polymers as Polyvinyl alcohol (PVA), Polyvinylpyrrolidone (PVP) and Polystirene (PS); composites with polymers as PVA+SnCl4; combined polymers as PS+Poly(styrene-alt-maleic anhydride) (PS+PSMA) and metal oxides (SnO2). In order to test the array, well-known chemical warfare agent simulants (CWAs) have been chosen among the volatile organic compounds due to their importance in the security field. Very low concentrations of these compounds have been detected by the array, such as 0.2 ppm of DMMP, a simulant of sarin nerve gas, and 1 ppm of DPGME, a simulant of nitrogen mustard. Additionally, the CWA simulants used in the experiment have been discriminated and classified using pattern recognition techniques, such as principal component analysis and artificial neural networks.

  12. Characterization of an array of Love-wave gas sensors developed using electrospinning technique to deposit nanofibers as sensitive layers.

    PubMed

    Matatagui, D; Fernández, M J; Fontecha, J; Sayago, I; Gràcia, I; Cané, C; Horrillo, M C; Santos, J P

    2014-03-01

    The electrospinning technique has allowed that very different materials are deposited as sensitive layers on Love-wave devices forming a low cost and successful sensor array. Their excellent sensitivity, good linearity and short response time are reported in this paper. Several materials have been used to produce the nanofibers: polymers as Polyvinyl alcohol (PVA), Polyvinylpyrrolidone (PVP) and Polystirene (PS); composites with polymers as PVA+SnCl4; combined polymers as PS+Poly(styrene-alt-maleic anhydride) (PS+PSMA) and metal oxides (SnO2). In order to test the array, well-known chemical warfare agent simulants (CWAs) have been chosen among the volatile organic compounds due to their importance in the security field. Very low concentrations of these compounds have been detected by the array, such as 0.2 ppm of DMMP, a simulant of sarin nerve gas, and 1 ppm of DPGME, a simulant of nitrogen mustard. Additionally, the CWA simulants used in the experiment have been discriminated and classified using pattern recognition techniques, such as principal component analysis and artificial neural networks. PMID:24468389

  13. Determination of the threshold odor concentration of main odorants in essential oils using gas chromatography-olfactometry incremental dilution technique.

    PubMed

    Benzo, Maurizio; Gilardoni, Gianluca; Gandini, Carlo; Caccialanza, Gabriele; Vita Finzi, Paola; Vidari, Giovanni; Abdo, Susana; Layedra, Patricia

    2007-05-25

    An essential oil, obtained by steam distillation of Clinopodium tomentosum (Kunth) Govaerts (Lamiaceae), collected in Ecuador, was analyzed by gas chromatography-olfactometry (GC-O) and GC-MS techniques. To our knowledge, the composition of this essential oil is described here for the first time, both from the chemical and olfactometric viewpoints. A preliminary analysis by GC-MS and using Kovats' retention indexes, lead to characterize and quantify the oil constituents, while GC-O was then applied for the identification of the main odorants. By the incremental dilution method (AEDA, CHARM Analysis), applied to the GC-O technique, the flavor dilution (FD) chromatogram was obtained. In order to calculate the TOC values of the main odorants, the relationship between the odorant concentration at the sniffing port and that one in the injected solution was established. This relationship was calculated by comparing the injected amount with the TOC value of a reference compound (limonene), obtained by dynamic dilution olfactometry. A good agreement was found between calculated and measured TOC values of few odorants.

  14. Development of a tunable diode laser absorption sensor for online monitoring of industrial gas total emissions based on optical scintillation cross-correlation technique.

    PubMed

    Zhang, Zhirong; Pang, Tao; Yang, Yang; Xia, Hua; Cui, Xiaojuan; Sun, Pengshuai; Wu, Bian; Wang, Yu; Sigrist, Markus W; Dong, Fengzhong

    2016-05-16

    We report the first application of gas total emission using a DFB diode laser for gas concentration measurements combined with two LEDs for gas velocity measurements. In situ gas total emissions and particle density measurements in an industrial pipeline using simultaneous tunable diode laser absorption spectroscopy (TDLAS) and optical scintillation cross-correlation technique (OSCC) are presented. Velocity mean values obtained are 7.59 m/s (OSCC, standard deviation is 1.37 m/s) and 8.20 m/s (Pitot tube, standard deviation is 1.47 m/s) in a steel plant pipeline for comparison. Our experiments demonstrate that the combined system of TDLAS and OSCC provides a new versatile tool for accurate measurements of total gas emissions. PMID:27409967

  15. Scrotal distension after endoscopic harvesting of the saphenous vein in patients with inguinal hernia.

    PubMed

    Najam, Osman; Krishnamoorthy, Bhuvana; Kadir, Isaac; Karagounis, Apostolos Paul; Waterworth, Paul; Fildes, James E; Yonan, Nizar

    2011-08-01

    The great saphenous vein remains the most commonly used conduit for coronary artery bypass grafting. The endoscopic vein harvesting technique is widely used due to reduced postoperative complications. We present the case of 5 patients with a history of inguinal hernia undergoing coronary artery bypass grafting, which resulted in CO2 infiltration through the deep inguinal ring and into the scrotum leading to acute scrotal enlargement. Due to the risk of impediment of vascular blood supply and necrosis, endoscopic vein harvesting was withdrawn, and the vein was harvested by using the bridging technique. Postoperatively, severe contusion, inflammation, and erythematous vesicular eruption resulted in a lengthened hospital stay.

  16. Simulation Based on Ion-Ion Plasma Techniques of Electric propulsion In Mars Mission Using Chlorine Gas

    NASA Astrophysics Data System (ADS)

    Sathiyavel, C.

    Abstract:The recently(Nov-5/2013) launched Mangalyan by the Indian space Research Organization (ISRO) to Mars orbit with Mankalyan contained by small liquid engine(MMH+N2O4).This will take long time to reach the Mars orbit that is around the 9 Months. Bi-Propellant rocket system has good thrust but low specific impulse and velocity. In future we need a rocket with good high specific impulse and high velocity of rocket system, to reduce the trip time to Mars. Electric propulsion rocket system is expected to become popular with the development of ion-ion pair techniques because this needs low propellant, Design thrust range is 1.5 N with high efficiency. An ion - ion pair of Electric propulsion rocket system is proposed in this work. Ion-Ion(positive ion- negative ion) Based Rocket system consists of three parts 1.The negative ionization stage with electro negative propellant 2. Ion-Ion plasma formation and ion accelerator 3. Exhaust of Nozzle. The Negative ions from electro negative gas are produced by adding up the gas, such as chlorine with electron emitted from an Electron gun ionization chamber. The formulate of large stable negative ion is achievable in chlorine gas with respect to electron affinity (∆E). When a neutral chlorine atom in the gaseous form picks up an electron to form a Cl- ion, it releases energy of 3.6eV. The negative ion density becomes several orders of magnitude larger than that of the electrons, hence forming ion-ion (positive ion - negative ion) plasma at the periphery of the discharge. The distance between ion- ions is important for the evaluate the rocket thrust and it also that the distance is determined by the exhaust velocity of the propellant. Accelerate the ion-ion plasma to a high velocity in the thrust vector direction via electron gun and the exhaust of ions through Nozzle. The simulation of the ion propulsion system has been carried out by MATLAB. By comparing the simulation results with the theoretical and previous results, we

  17. Uncertainty in anticipation of uncomfortable rectal distension is modulated by the autonomic nervous system--a fMRI study in healthy volunteers.

    PubMed

    Rubio, Amandine; Van Oudenhove, Lukas; Pellissier, Sonia; Ly, Huynh Giao; Dupont, Patrick; de Micheaux, Hugo Lafaye; Tack, Jan; Dantzer, Cécile; Delon-Martin, Chantal; Bonaz, Bruno

    2015-02-15

    The human brain responds both before and during the application of aversive stimuli. Anticipation allows the organism to prepare its nociceptive system to respond adequately to the subsequent stimulus. The context in which an uncomfortable stimulus is experienced may also influence neural processing. Uncertainty of occurrence, timing and intensity of an aversive event may lead to increased anticipatory anxiety, fear, physiological arousal and sensory perception. We aimed to identify, in healthy volunteers, the effects of uncertainty in the anticipation of uncomfortable rectal distension, and the impact of the autonomic nervous system (ANS) activity and anxiety-related psychological variables on neural mechanisms of anticipation of rectal distension using fMRI. Barostat-controlled uncomfortable rectal distensions were preceded by cued uncertain or certain anticipation in 15 healthy volunteers in a fMRI protocol at 3T. Electrocardiographic data were concurrently registered by MR scanner. The low frequency (LF)-component of the heart rate variability (HRV) time-series was extracted and inserted as a regressor in the fMRI model ('LF-HRV model'). The impact of ANS activity was analyzed by comparing the fMRI signal in the 'standard model' and in the 'LF-HRV model' across the different anticipation and distension conditions. The scores of the psychological questionnaires and the rating of perceived anticipatory anxiety were included as covariates in the fMRI data analysis. Our experiments led to the following key findings: 1) the subgenual anterior cingulate cortex (sgACC) is the only activation site that relates to uncertainty in healthy volunteers and is directly correlated to individual questionnaire score for pain-related anxiety; 2) uncertain anticipation of rectal distension involved several relevant brain regions, namely activation of sgACC and medial prefrontal cortex and deactivation of amygdala, insula, thalamus, secondary somatosensory cortex, supplementary

  18. Study of the Behaviors of Gunshot Residues from Spent Cartridges by Headspace Solid-Phase Microextraction-Gas Chromatographic Techniques.

    PubMed

    Chang, Kah Haw; Yew, Chong Hooi; Abdullah, Ahmad Fahmi Lim

    2015-07-01

    Gunshot residues, produced after shooting activity, have acquired their importance in analysis due to the notoriety of firearms-related crimes. In this study, solid-phase microextraction was performed to extract the headspace composition of spent cartridges using 85-μm polyacrylate fiber at 66°C for 21 min. Organic compounds, that is, naphthalene, 2,6-dinitrotoluene, 2,4-dinitrotoluene, diphenylamine, and dibutyl phthalate were detected and analyzed by gas chromatography-flame ionization detection technique. Evaluation of chromatograms for diphenylamine, dibutyl phthalate, and naphthalene indicates the period after a gunshot was discharged, whether it was 1 days, 2-4 days, <5 days, 10 days, 20 days, or more than 30 days ago. This study revealed the potential effects of environmental factors such as occasional wind blow and direct sunlight on the estimation of time after spent cartridges were discharged. In conclusion, we proposed reliable alternative in analyzing the headspace composition of spent cartridges in a simulated crime scene. PMID:25771708

  19. Low-cost gas sensors produced by the graphite line-patterning technique applied to monitoring banana ripeness.

    PubMed

    Manzoli, Alexandra; Steffens, Clarice; Paschoalin, Rafaella T; Correa, Alessandra A; Alves, William F; Leite, Fábio L; Herrmann, Paulo S P

    2011-01-01

    A low-cost sensor array system for banana ripeness monitoring is presented. The sensors are constructed by employing a graphite line-patterning technique (LPT) to print interdigitated graphite electrodes on tracing paper and then coating the printed area with a thin film of polyaniline (PANI) by in-situ polymerization as the gas-sensitive layer. The PANI layers were used for the detection of volatile organic compounds (VOCs), including ethylene, emitted during ripening. The influence of the various acid dopants, hydrochloric acid (HCl), methanesulfonic acid (MSA), p-toluenesulfonic acid (TSA) and camphorsulfonic acid (CSA), on the electrical properties of the thin film of PANI adsorbed on the electrodes was also studied. The extent of doping of the films was investigated by UV-Vis absorption spectroscopy and tests showed that the type of dopant plays an important role in the performance of these low-cost sensors. The array of three sensors, without the PANI-HCl sensor, was able to produce a distinct pattern of signals, taken as a signature (fingerprint) that can be used to characterize bananas ripeness. PMID:22163963

  20. Low-Cost Gas Sensors Produced by the Graphite Line-Patterning Technique Applied to Monitoring Banana Ripeness

    PubMed Central

    Manzoli, Alexandra; Steffens, Clarice; Paschoalin, Rafaella T.; Correa, Alessandra A.; Alves, William F.; Leite, Fábio L.; Herrmann, Paulo S. P.

    2011-01-01

    A low-cost sensor array system for banana ripeness monitoring is presented. The sensors are constructed by employing a graphite line-patterning technique (LPT) to print interdigitated graphite electrodes on tracing paper and then coating the printed area with a thin film of polyaniline (PANI) by in-situ polymerization as the gas-sensitive layer. The PANI layers were used for the detection of volatile organic compounds (VOCs), including ethylene, emitted during ripening. The influence of the various acid dopants, hydrochloric acid (HCl), methanesulfonic acid (MSA), p-toluenesulfonic acid (TSA) and camphorsulfonic acid (CSA), on the electrical properties of the thin film of PANI adsorbed on the electrodes was also studied. The extent of doping of the films was investigated by UV-Vis absorption spectroscopy and tests showed that the type of dopant plays an important role in the performance of these low-cost sensors. The array of three sensors, without the PANI-HCl sensor, was able to produce a distinct pattern of signals, taken as a signature (fingerprint) that can be used to characterize bananas ripeness. PMID:22163963

  1. Gas-phase ion chemistry of Cr(. eta. sup 6 -arene)(CO) sub 3 complexes by FTMS techniques

    SciTech Connect

    Operti, L.; Vaglio, G.A. ); Gord, J.R.; Freiser, B.S. )

    1991-01-01

    The gas-phase reactivities of eight Cr({eta}{sup 6}-arene)(CO){sub 3} complexes (arene = toluene, mesitylene, PhCOOOMe, PhCOMe, PhCOEt, PhCO-n-Pr, PhCO-t-Bu, PhCH{sub 2}COMe) have been studied by FTMS techniques. Self-condensation processes occur that follow different reaction pathways when the coordinated arene is a hydrocarbon or a phenyl ketone. PhCOOOMe and PhCH{sub 2}COMe show an intermediate behavior. Reactions with free arenes or propene give substitution of the carbonyl groups, yielding Cr(arene)(arene{prime}){sup +} and Cr(arene)(propene){sup +}, respectively. The extent to which displacement takes place depends on the nature of the original coordinated arene and is higher when it contains a CO group. With suitable free arenes as reagent gases, arene displacement is also observed, producing Cr(arene{prime}){sub 2}{sup +}. The formation of the disubstituted ions depends, once again, on the nature of the coordinated arene as well as on the relative bond energy of Cr{sup +}-arene{prime} with respect to Cr{sup +}-arene. CID experiments have been performed in order to obtain a sequence of relative binding energies of the arenes to Cr{sup +}. The results are consistent with the electronic and steric properties of the arene ligands, which affect the Cr{sup +}-arene bond strength.

  2. Low-cost gas sensors produced by the graphite line-patterning technique applied to monitoring banana ripeness.

    PubMed

    Manzoli, Alexandra; Steffens, Clarice; Paschoalin, Rafaella T; Correa, Alessandra A; Alves, William F; Leite, Fábio L; Herrmann, Paulo S P

    2011-01-01

    A low-cost sensor array system for banana ripeness monitoring is presented. The sensors are constructed by employing a graphite line-patterning technique (LPT) to print interdigitated graphite electrodes on tracing paper and then coating the printed area with a thin film of polyaniline (PANI) by in-situ polymerization as the gas-sensitive layer. The PANI layers were used for the detection of volatile organic compounds (VOCs), including ethylene, emitted during ripening. The influence of the various acid dopants, hydrochloric acid (HCl), methanesulfonic acid (MSA), p-toluenesulfonic acid (TSA) and camphorsulfonic acid (CSA), on the electrical properties of the thin film of PANI adsorbed on the electrodes was also studied. The extent of doping of the films was investigated by UV-Vis absorption spectroscopy and tests showed that the type of dopant plays an important role in the performance of these low-cost sensors. The array of three sensors, without the PANI-HCl sensor, was able to produce a distinct pattern of signals, taken as a signature (fingerprint) that can be used to characterize bananas ripeness.

  3. Effects of sensor location and the atmospheric stability on the accuracy of an inverse-dispersion technique for lagoon gas emission measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measuring gas emission rates from wastewater lagoons and storage ponds using currently available micrometeorological techniques can be an arduous task because typical lagoon environments contain a variety of obstructions (e.g., berm, trees, buildings) to wind flow. These non-homogeneous terrain cond...

  4. Portomesenteric venous gas in a 2-week-old Holstein calf.

    PubMed

    Hirsch, Gaelle; Silva, Goncalo; zur Linden, Alex; Needham, Hank; Arroyo, Luis G

    2013-10-01

    A 2-week-old Holstein Friesian female calf was presented with profuse diarrhea and abdominal distension. Clinicopathological findings included marked hypoproteinemia, hypoglycemia and leucopenia, mild hyperlactatemia, and hyperfibrinogenemia. On abdominal ultrasonography, features were consistent with portomesenteric venous gas (PVG), a rare condition reported in the medical literature. The PVG in this calf was associated with severe gastrointestinal illness and sepsis.

  5. Sample Processing technique onboard ExoMars (MOMA) to analyze organic compounds by Gas Chromatography-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Buch, A.; Freissinet, C.; Sternberg, R.; Szopa, C.; Coll, P. J.; Brault, A.; Pinnick, V.; Siljeström, S.; Raulin, F.; Steininger, H.; Goesmann, F.; MOMA Team

    2011-12-01

    With the aim of separating and detecting organic compounds from Martian soil onboard the Mars Organic Molecule Analyzer (MOMA) experiment of the ExoMars 2018 upcoming joint ESA/NASA mission, we have developed three different space compatible sample preparation techniques compatible with space missions, able to extract and analyze by GC-MS a wide range of volatile and refractory compounds, including chirality analysis. Then, a sample processing utilizing three derivatization/extraction reactions has been carried out. The first reaction is based on a silyl reagent N-Methyl-N- (Tert-Butyldimethylsilyl)trifluoroacetamide (MTBSTFA) [1], the second one, N,N-Dimethylformamide Dimethylacetal (DMF-DMA) [2,3] is dedicated to the chirality detection and the third one is a thermochemolysis based on the use of tetramethylammoniumhydroxide (TMAH). The sample processing system is performed in an oven, dedicated to the MOMA experiment containing the solid sample (50-100mg). The internal temperature of the oven ranges from 20 to 900 °C. The extraction step is achieved by using thermodesorption in the range of 100 to 300°C for 5 to 20 min. Then, the chemical derivatization of the extracted compounds is performed directly on the soil sample by using a derivatyization capsule which contains a mixture of MTBSTFA-DMF or DMF-DMA solution when enantiomeric separation is required. By decreasing the polarity of the targeted molecules, this step allows their volatilization at a temperature below 250°C without any thermal degradation. Once derivatized, the volatile target molecules are trapped in a chemical trap and promptly desorbed into the gas chromatograph coupled to a mass spectrometer. Thermochemolysis is directly performed in the oven at 400°C during 5 min with a 25% (w/w) methanol solution of tetramethylammonium hydroxide (TMAH). Then, pyrolysis in the presence of TMAH allows both an efficient cleavage of polar bonds and the subsequent methylation of COOH, OH and NH2 groups, hence

  6. Evaluating of scale-up methodologies of gas-solid spouted beds for coating TRISO nuclear fuel particles using advanced measurement techniques

    NASA Astrophysics Data System (ADS)

    Ali, Neven Y.

    The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking (RPT) to measure in three-dimension (3D) solids velocity and their turbulent parameters. The measured local parameters and the analysis of the results obtained in this work validate our new methodology of scale up of gas-solid spouted beds by comparing for the similarity the phases' holdups and the dimensionless solids velocities and their turbulent parameters that are non-dimensionalized using the minimum spouting superficial gas velocity. However, the scale-up methodology of gas-solid spouted beds that is based on matching dimensionless groups has not been validated for hydrodynamics similarity with respect to the local parameters such as phases' holdups and dimensionless solids velocities and their turbulent parameters. Unfortunately, this method was validated in the literature by only measuring the global parameters. Thus, this work confirms that validation of the scale-up methods of gas-solid spouted beds for hydrodynamics similarity should reside on measuring and analyzing the local hydrodynamics parameters.

  7. A novel Fast Gas Chromatography based technique for higher time resolution measurements of speciated monoterpenes in air

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

    2013-12-01

    Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C10-C15 BVOC composition of single plant emissions may be characterised within a ~ 14 min analysis time. Moreover, in situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an ~ 11 min chromatographic separation time (increasing to ~ 19 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). This corresponds to a two- to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC linalool in ambient air. During this field deployment within a suburban forest ~ 30 km west of central Tokyo, Japan, the

  8. Mutually supportive use of stable isotope and gas chromatography techniques to understand ecohydrological interactions in dryland environments

    NASA Astrophysics Data System (ADS)

    Puttock, A.; Brazier, R. E.; Dungait, J. A. J.; Bol, R.; Dixon, E. R.; Macleod, C. J. A.

    2012-04-01

    Many drylands globally are experiencing extensive vegetation change. In the semi-arid Southwestern United States, this change is characterised by the encroachment of woody vegetation into environments previously dominated by grassland (Van Auken. 2009). The transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al. 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage and an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. This project uses an ecohydrological approach, monitoring natural rainfall-runoff events and resulting water and sediment fluxes over six bounded plots with different vegetation coverage at the Sevilleta National Wildlife Refuge, New Mexico, USA. The experiment takes advantage of a shift in the photosynthetic pathway of dominant vegetation from C3 piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand through a C4 pure-grass (Bouteloua eriopoda) to C3 shrub (Larrea tridentate). This allows for the utilisation of natural abundance tracing techniques, specifically stable 13C isotope and gas chromatography lipid biomarker analyses. Results collected during the 2010 and 2011 monsoon seasons will be presented, using biogeochemical signatures, to trace and partition fluvial soil organic matter and carbon fluxes during runoff generating rainfall events. Results show that biogeochemical signatures specific to individual plant species can be used to define the provenance of carbon, quantifying whether more Pinus edulis-Juniperus monosperma derived carbon is mobilised from the upland plots, or whether more Larrea tridentata carbon is lost when compared to bouteloa eripoda losses in the lowlands. Results also show that biogeochemical signatures vary with event characteristics, raising the possibility of using these tracing

  9. Continuous monitoring of soil gas efflux with Forced Diffusion (FD) chamber technique in a tundra ecosystem, Alaska

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Park, S. J.; Lee, B. Y.

    2015-12-01

    Continuous measurements of soil carbon dioxide (CO2) efflux provide essential information about the soil carbon budget in response to an abruptly changing climate at Arctic and Subarctic scales. The Forced Diffusion (FD) chamber technique has a gas permeable membrane, which passively regulates the mixing of atmosphere and soil air in the chamber, in place of the active pumping system inside a regular dynamics efflux chamber system (Risk et al., 2011). Here the system has been modified the sampling routine to eliminate the problem of sensor drift. After that, we deployed the FD chamber system in a tundra ecosystem over the discontinuous permafrost regime of Council, Alaska. The representative understory plants are tussock (17 %), lichen (32 %), and moss (51 %), within a 40 נ40 m plot at an interval of five meters (81 points total) for efflux-measurement by dynamic chamber. The FD chamber monitored soil CO2 efflux from moss, lichen, and tussock regimes at an interval of 30 min during the growing season of 2015. As the results, mean soil CO2 effluxes in sphagnum moss, lichen, and tussock were 1.98 ± 1.10 (coefficient of variance: 55.8 %), 3.34 ± 0.84 (CV: 25.0 %), and 5.32 ± 1.48 (CV: 27.8 %) gCO2/m2/d, respectively. The difference between the 30-min efflux interval and the average efflux of three 10-min intervals is not significant for sphagnum (n = 196), lichen (n = 918), and tussock (n = 918) under a 95 % confidence level. The deploying interval was then set to 30 min and synchronized with eddy covariance tower data. During the deployment period of 2015, soil CO2 efflux over moss, lichen, and tussock using the FD chamber system were 44 ± 24, 73 ± 18, and 117 ± 33 gCO2/m2/period, respectively. Using the dynamic chamber, mean ecosystem respiration (Re) ranges for moss, lichen, and tussock were 2.2-2.6, 1.8-2.0, and 3.3-3.6 gCO2/m2/d, respectively, during June and July of 2015. These techniques provide the representativeness of spatiotemporal variation of soil

  10. A review on risk assessment techniques for hydraulic fracturing water and produced water management implemented in onshore unconventional oil and gas production.

    PubMed

    Torres, Luisa; Yadav, Om Prakash; Khan, Eakalak

    2016-01-01

    The objective of this paper is to review different risk assessment techniques applicable to onshore unconventional oil and gas production to determine the risks to water quantity and quality associated with hydraulic fracturing and produced water management. Water resources could be at risk without proper management of water, chemicals, and produced water. Previous risk assessments in the oil and gas industry were performed from an engineering perspective leaving aside important social factors. Different risk assessment methods and techniques are reviewed and summarized to select the most appropriate one to perform a holistic and integrated analysis of risks at every stage of the water life cycle. Constraints to performing risk assessment are identified including gaps in databases, which require more advanced techniques such as modeling. Discussions on each risk associated with water and produced water management, mitigation strategies, and future research direction are presented. Further research on risks in onshore unconventional oil and gas will benefit not only the U.S. but also other countries with shale oil and gas resources.

  11. A review on risk assessment techniques for hydraulic fracturing water and produced water management implemented in onshore unconventional oil and gas production.

    PubMed

    Torres, Luisa; Yadav, Om Prakash; Khan, Eakalak

    2016-01-01

    The objective of this paper is to review different risk assessment techniques applicable to onshore unconventional oil and gas production to determine the risks to water quantity and quality associated with hydraulic fracturing and produced water management. Water resources could be at risk without proper management of water, chemicals, and produced water. Previous risk assessments in the oil and gas industry were performed from an engineering perspective leaving aside important social factors. Different risk assessment methods and techniques are reviewed and summarized to select the most appropriate one to perform a holistic and integrated analysis of risks at every stage of the water life cycle. Constraints to performing risk assessment are identified including gaps in databases, which require more advanced techniques such as modeling. Discussions on each risk associated with water and produced water management, mitigation strategies, and future research direction are presented. Further research on risks in onshore unconventional oil and gas will benefit not only the U.S. but also other countries with shale oil and gas resources. PMID:26386446

  12. Estimating regional greenhouse gas fluxes: An uncertainty analysis of planetary boundary layer techniques and bottom-up inventories

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of regional greenhouse gas (GHG) fluxes is essential for establishing mitigation strategies and evaluating their effectiveness. Here, we used multiple top-down approaches and multiple trace gas observations at a tall tower to estimate GHG regional fluxes and evaluate the GHG fluxes de...

  13. Regular physical activity is associated with improved small artery distensibility in young to middle-age stage 1 hypertensives.

    PubMed

    Saladini, Francesca; Benetti, Elisabetta; Mos, Lucio; Mazzer, Adriano; Casiglia, Edoardo; Palatini, Paolo

    2014-12-01

    The aim of the present study was to investigate the association of physical activity with small artery elasticity in the early stage of hypertension. We examined 366 young-to-middle-age stage 1 hypertensives (mean blood pressure 145.6±10.3/92.5±5.8 mmHg), divided into two categories of physical activity, sedentary (n=264) and non-sedentary (n=102) subjects. The augmentation index was measured using the Specaway DAT System. Small artery compliance (C2) was measured by applanation tonometry, at the radial artery, with an HDI CR2000 device. After 6 years of follow-up, arterial distensibility assessment was repeated in 151 subjects. Heart rate was lower in active than in sedentary subjects (71.2±8.9 vs 76.6±9.7 bpm, p<0.001). After adjusting for age, sex, heart rate, smoking, and blood pressure, C2 was higher (8.0±2.6 vs 6.4±3.0 ml/mmHg × 100, p=0.008) in non-sedentary than in sedentary patients. The augmentation index was smaller in the former (8.8±20.1 vs 16.8±26.5%, p=0.044) but the difference lost statistical significance after further adjustment for blood pressure. After 6 years, C2 was still higher in the non-sedentary than sedentary subjects. In addition, an improvement in the augmentation index accompanied by a decline in total peripheral resistance was found in the former. These data show that regular physical activity is associated with improved small artery elasticity in the early phase of hypertension. This association persists over time and is independent of blood pressure and heart rate.

  14. At high cardiac output, diesel exhaust exposure increases pulmonary vascular resistance and decreases distensibility of pulmonary resistive vessels.

    PubMed

    Wauters, Aurélien; Vicenzi, Marco; De Becker, Benjamin; Riga, Jean-Philippe; Esmaeilzadeh, Fatemeh; Faoro, Vitalie; Vachiéry, Jean-Luc; van de Borne, Philippe; Argacha, Jean-François

    2015-12-15

    Air pollution has recently been associated with the development of acute decompensated heart failure, but the underlying biological mechanisms remain unclear. A pulmonary vasoconstrictor effect of air pollution, combined with its systemic effects, may precipitate decompensated heart failure. The aim of the present study was to investigate the effects of acute exposure to diesel exhaust (DE) on pulmonary vascular resistance (PVR) under resting and stress conditions but also to determine whether air pollution may potentiate acquired pulmonary hypertension. Eighteen healthy male volunteers were exposed to ambient air (AA) or dilute DE with a particulate matter of <2.5 μm concentration of 300 μg/m(3) for 2 h in a randomized, crossover study design. The effects of DE on PVR, on the coefficient of distensibilty of pulmonary vessels (α), and on right and left ventricular function were evaluated at rest (n = 18), during dobutamine stress echocardiography (n = 10), and during exercise stress echocardiography performed in hypoxia (n = 8). Serum endothelin-1 and fractional exhaled nitric oxide were also measured. At rest, exposure to DE did not affect PVR. During dobutamine stress, the slope of the mean pulmonary artery pressure-cardiac output relationship increased from 2.8 ± 0.5 mmHg · min · l (-1) in AA to 3.9 ± 0.5 mmHg · min · l (-1) in DE (P < 0.05) and the α coefficient decreased from 0.96 ± 0.15 to 0.64 ± 0.12%/mmHg (P < 0.01). DE did not further enhance the hypoxia-related upper shift of the mean pulmonary artery pressure-cardiac output relationship. Exposure to DE did not affect serum endothelin-1 concentration or fractional exhaled nitric oxide. In conclusion, acute exposure to DE increased pulmonary vasomotor tone by decreasing the distensibility of pulmonary resistive vessels at high cardiac output. PMID:26497960

  15. Electrocardiogram-Gated 320-Slice Multidetector Computed Tomography for the Measurement of Pulmonary Arterial Distensibility in Chronic Thromboembolic Pulmonary Hypertension

    PubMed Central

    Kasai, Hajime; Sugiura, Toshihiko; Tanabe, Nobuhiro; Sakurai, Yoriko; Yahaba, Misuzu; Matsuura, Yukiko; Shigeta, Ayako; Kawata, Naoko; Sakao, Seiichiro; Kasahara, Yasunori; Tatsumi, Koichiro

    2014-01-01

    Background We aimed to study whether pulmonary arterial distensibility (PAD) correlates with hemodynamic parameters in chronic thromboembolic pulmonary hypertension (CTEPH) using electrocardiogram (ECG)-gated 320-slice multidetector computed tomography (MDCT). Methods and Findings ECG-gated 320-slice MDCT and right heart catheterization (RHC) was performed in 53 subjects (60.6±11.4 years old; 37 females) with CTEPH. We retrospectively measured the minimum and maximum values of the cross sectional area (CSA) of the main pulmonary artery (mainPA), right pulmonary artery (rtPA), and left pulmonary artery (ltPA) during one heartbeat. PAD was calculated using the following formula: PAD = [(CSAmaximum−CSAminimum)/CSAmaximum]×100(%). The correlation between hemodynamic parameters and PAD was assessed. Mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) were 40.8±8.7 mmHg and 8.3±3.0 wood units, respectively. PAD values were as follows: mainPA (14.0±5.0%), rtPA (12.8±5.6%), and ltPA (9.7±4.6%). Good correlations existed between mainPAD, with mPAP (r = −0.594, p<0.001) and PVR (r = −0.659, p<0.001). The correlation coefficients between rtPAD and ltPAD with pulmonary hemodynamics were all lower or equal than for mainPAD. Conclusions PAD measured using ECG-gated 320-slice MDCT correlates with pulmonary hemodynamics in subjects with CTEPH. The mainPA is suitable for PAD measurement. PMID:25365168

  16. Effect of Bladder Distension on Dose Distribution of Intracavitary Brachytherapy for Cervical Cancer: Three-Dimensional Computed Tomography Plan Evaluation

    SciTech Connect

    Cengiz, Mustafa Guerdalli, Salih; Selek, Ugur; Yildiz, Ferah; Saglam, Yuecel; Ozyar, Enis; Atahan, I. Lale

    2008-02-01

    Purpose: To quantify the effect of bladder volume on the dose distribution during intracavitary brachytherapy for cervical cancer. Methods and Patients: The study was performed on 10 women with cervical cancer who underwent brachytherapy treatment. After insertion of the brachytherapy applicator, the patients were transferred to the computed tomography unit. Two sets of computed tomography slices were taken, including the pelvis, one with an empty bladder and one after the bladder was filled with saline. The target and critical organs were delineated by the radiation oncologist and checked by the expert radiologist. The radiotherapy plan was run on the Plato planning system, version 14.1, to determine the dose distributions, dose-volume histograms, and maximal dose points. The doses and organ volumes were compared with the Wilcoxon signed ranks test on a personal computer using the Statistical Package for Social Sciences, version 11.0, statistical program. Results: No significant difference regarding the dose distribution and target volumes between an empty or full bladder was observed. Bladder fullness significantly affected the dose to the small intestine, rectum, and bladder. The median of maximal doses to the small intestine was significantly greater with an empty bladder (493 vs. 284 cGy). Although dosimetry revealed lower doses for larger volumes of bladder, the median maximal dose to the bladder was significantly greater with a full bladder (993 vs. 925 cGy). The rectal doses were also affected by bladder distension. The median maximal dose was significantly lower in the distended bladder (481vs. 628 cGy). Conclusions: Bladder fullness changed the dose distributions to the bladder, rectum, and small intestine. The clinical importance of these changes is not known and an increase in the use of three-dimensional brachytherapy planning will highlight the answer to this question.

  17. At high cardiac output, diesel exhaust exposure increases pulmonary vascular resistance and decreases distensibility of pulmonary resistive vessels.

    PubMed

    Wauters, Aurélien; Vicenzi, Marco; De Becker, Benjamin; Riga, Jean-Philippe; Esmaeilzadeh, Fatemeh; Faoro, Vitalie; Vachiéry, Jean-Luc; van de Borne, Philippe; Argacha, Jean-François

    2015-12-15

    Air pollution has recently been associated with the development of acute decompensated heart failure, but the underlying biological mechanisms remain unclear. A pulmonary vasoconstrictor effect of air pollution, combined with its systemic effects, may precipitate decompensated heart failure. The aim of the present study was to investigate the effects of acute exposure to diesel exhaust (DE) on pulmonary vascular resistance (PVR) under resting and stress conditions but also to determine whether air pollution may potentiate acquired pulmonary hypertension. Eighteen healthy male volunteers were exposed to ambient air (AA) or dilute DE with a particulate matter of <2.5 μm concentration of 300 μg/m(3) for 2 h in a randomized, crossover study design. The effects of DE on PVR, on the coefficient of distensibilty of pulmonary vessels (α), and on right and left ventricular function were evaluated at rest (n = 18), during dobutamine stress echocardiography (n = 10), and during exercise stress echocardiography performed in hypoxia (n = 8). Serum endothelin-1 and fractional exhaled nitric oxide were also measured. At rest, exposure to DE did not affect PVR. During dobutamine stress, the slope of the mean pulmonary artery pressure-cardiac output relationship increased from 2.8 ± 0.5 mmHg · min · l (-1) in AA to 3.9 ± 0.5 mmHg · min · l (-1) in DE (P < 0.05) and the α coefficient decreased from 0.96 ± 0.15 to 0.64 ± 0.12%/mmHg (P < 0.01). DE did not further enhance the hypoxia-related upper shift of the mean pulmonary artery pressure-cardiac output relationship. Exposure to DE did not affect serum endothelin-1 concentration or fractional exhaled nitric oxide. In conclusion, acute exposure to DE increased pulmonary vasomotor tone by decreasing the distensibility of pulmonary resistive vessels at high cardiac output.

  18. PIGC™ - A low cost fugitive emissions and methane detection system using advanced gas filter correlation techniques for local and wide area monitoring

    NASA Astrophysics Data System (ADS)

    Lachance, R. L.; Gordley, L. L.; Marshall, B. T.; Fisher, J.; Paxton, G.; Gubeli, J. F.

    2015-12-01

    Currently there is no efficient and affordable way to monitor gas releases over small to large areas. We have demonstrated the ability to accurately measure key greenhouse and pollutant gasses with low cost solar observations using the breakthrough sensor technology called the "Pupil Imaging Gas Correlation", PIGC™, which provides size and complexity reduction while providing exceptional resolution and coverage for various gas sensing applications. It is a practical implementation of the well-known Gas Filter Correlation Radiometry (GFCR) technique used for the HALOE and MOPITT satellite instruments that were flown on successful NASA missions in the early 2000s. This strong space heritage brings performance and reliability to the ground instrument design. A methane (CH4) abundance sensitivity of 0.5% or better of ambient column with uncooled microbolometers has been demonstrated with 1 second direct solar observations. These under $10 k sensors can be deployed in precisely balanced autonomous grids to monitor the flow of chosen gasses, and infer their source locations. Measureable gases include CH4, 13CO2, N2O, NO, NH3, CO, H2S, HCN, HCl, HF, HDO and others. A single instrument operates in a dual operation mode, at no additional cost, for continuous (real-time 24/7) local area perimeter monitoring for the detection of leaks for safety & security needs, looking at an artificial light source (for example a simple 60 W light bulb placed 100 m away), while simultaneously allowing solar observation for quasi-continuous wide area total atmospheric column scanning (3-D) for environmental monitoring (fixed and mobile configurations). The second mode of operation continuously quantifies the concentration and flux of specific gases over different ground locations, determined the amount of targeted gas being released from the area or getting into the area from outside locations, allowing better tracking of plumes and identification of sources. This paper reviews the

  19. Predictive Value of Carotid Distensibility Coefficient for Cardiovascular Diseases and All-Cause Mortality: A Meta-Analysis

    PubMed Central

    Yuan, Chuang; Wang, Jing; Ying, Michael

    2016-01-01

    Aims The aim of the present study is to determine the pooled predictive value of carotid distensibility coefficient (DC) for cardiovascular (CV) diseases and all-cause mortality. Background Arterial stiffness is associated with future CV events. Aortic pulse wave velocity is a commonly used predictor for CV diseases and all-cause mortality; however, its assessment requires specific devices and is not always applicable in all patients. In addition to the aortic artery, the carotid artery is also susceptible to atherosclerosis, and is highly accessible because of the surficial property. Thus, carotid DC, which indicates the intrinsic local stiffness of the carotid artery and may be determined using ultrasound and magnetic resonance imaging, is of interest for the prediction. However, the role of carotid DC in the prediction of CV diseases and all-cause mortality has not been thoroughly characterized, and the pooled predictive value of carotid DC remains unclear. Methods A meta-analysis, which included 11 longitudinal studies with 20361 subjects, was performed. Results Carotid DC significantly predicted future total CV events, CV mortality and all-cause mortality. The pooled risk ratios (RRs) of CV events, CV mortality and all-cause mortality were 1.19 (1.06–1.35, 95%CI, 9 studies with 18993 subjects), 1.09 (1.01–1.18, 95%CI, 2 studies with 2550 subjects) and 1.65 (1.15–2.37, 95%CI, 6 studies with 3619 subjects), respectively, for the subjects who had the lowest quartile of DC compared with their counterparts who had higher quartiles. For CV events, CV mortality and all-cause mortality, a decrease in DC of 1 SD increased the risk by 13%, 6% and 41% respectively, whereas a decrease in DC of 1 unit increased the risk by 3%, 1% and 6% respectively. Conclusions Carotid DC is a significant predictor of future CV diseases and all-cause mortality, which may facilitate the identification of high-risk patients for the early diagnosis and prompt treatment of CV diseases

  20. Propylation technique for the simultaneous determination of tetraalkyllead and ionic alkyllead species by gas chromatography/atomic absorption spectrometry

    SciTech Connect

    Radojevic, M.; Allen, A.; Rapsomanikis, S.; Harrison, R.M.

    1986-03-01

    The only technique capable of simultaneous determination of R/sub 4/Pb and ionic alkyllead compounds involves extraction into an organic solvent in the presence of sodium diethyldithiocarbamate (NaDDTC) and derivatizations of ionic species to R/sub 4/Pb forms using a butylating Grignard reagent (n-butylmagnesium chloride) followed by GC/AAS analysis. This technique has been applied to many environmental samples with some degree of success, although for many less polluted samples even greater sensitivity is required. In this communication the authors present an improved and novel derivatization technique of the simultaneous determination R/sub 4/Pb and ionic alkyllead species involving extraction into n-hexane and propylation to the tetraalkyllead form using propylmagnesium chloride with GC/electrothermal AAS analysis. The technique is compared to the previously reported butylation method, and procedures of extract concentration are investigated. 11 references, 2 figures, 1 table.

  1. Laser technique in management of laryngomalacia

    NASA Astrophysics Data System (ADS)

    Shah, Udayan K.; McGuirt, William F., Jr.; Wetmore, Ralph F.; Healy, Gerald B.

    1998-07-01

    Laryngomalacia is the most common cause of newborn stridor. Management can usually be accomplished without surgery. When surgery is necessary, the carbon dioxide (CO2) laser plays an essential role in enabling precise, hemostatic dissection. The authors present their application of the CO2 laser with microspot control for laser correction of laryngomalacia, with emphasis upon the use of the Boston University suspension system to achieve external suspension of the larynx and the bivalved laryngoscope to achieve tissue distension. Review of indications, technique and results is shared to detail the utility of the CO2 laser in supraglottoplasty.

  2. Data acquisition techniques for exploiting the uniqueness of the time-of-flight mass spectrometer: Application to sampling pulsed gas systems

    NASA Technical Reports Server (NTRS)

    Lincoln, K. A.

    1980-01-01

    Mass spectra are produced in most mass spectrometers by sweeping some parameter within the instrument as the sampled gases flow into the ion source. It is evident that any fluctuation in the gas during the sweep (mass scan) of the instrument causes the output spectrum to be skewed in its mass peak intensities. The time of flight mass spectrometer (TOFMS) with its fast, repetitive mode of operation produces spectra without skewing or varying instrument parameters and because all ion species are ejected from the ion source simultaneously, the spectra are inherently not skewed despite rapidly changing gas pressure or composition in the source. Methods of exploiting this feature by utilizing fast digital data acquisition systems, such as transient recorders and signal averagers which are commercially available are described. Applications of this technique are presented including TOFMS sampling of vapors produced by both pulsed and continuous laser heating of materials.

  3. Effect of support materials on supported platinum catalyst prepared using a supercritical fluid deposition technique and their catalytic performance for hydrogen-rich gas production from lignocellulosic biomass.

    PubMed

    Kaya, Burçak; Irmak, Sibel; Hesenov, Arif; Erbatur, Oktay; Erkey, Can

    2012-11-01

    A number of supported Pt catalysts have been prepared by supercritical carbon dioxide deposition technique using various supports. The reduction of Pt precursor to metal performed by heat treatment under nitrogen flow. The prepared catalysts were evaluated for gasification of wheat straw biomass hydrolysates and glucose solution for hydrogen-rich gas production. The activities of the catalysts were highly affected by distribution, amount and particle sizes of platinum on the support. In general carbon-based supported Pt catalysts exhibited better catalytic activity compared to other supports to be used. Compared to biomass hydrolysate feed, gasification of glucose always resulted in higher volume of gas mixture, however, hydrogen selectivity was decreased in all catalyst except multi-walled carbon nanotube. The deposition of Pt particles inner side of that support makes the large organic substrates inaccessible to reach and react with those metal particles.

  4. Gas-phase spectroscopy and anharmonic vibrational analysis of the 3-residue peptide Z-Pro-Leu-Gly-NH2 by the laser desorption supersonic jet technique

    NASA Astrophysics Data System (ADS)

    Ishiuchi, Shun-ichi; Yamada, Kohei; Chakraborty, Shamik; Yagi, Kiyoshi; Fujii, Masaaki

    2013-06-01

    The electronic excitation and infrared (IR) spectra of a capped tri-peptide, Z-PLG-NH2 (Z = benzyloxycarbonyl, P = Pro, L = Leu, G = Gly), were measured in the gas phase by using the laser desorption supersonic jet technique. By measuring an ultraviolet-ultraviolet hole burning spectrum, it was found that Z-PLG-NH2 has the maximum three conformers in the gas phase, but that the population is mainly distributed to a single conformation. Molecular dynamics simulations and density functional theory calculations well-reproduced the observed IR spectrum, except for splitting of the NH stretching bands by a β-turn structure that corresponds to a global minimum structure. Anharmonic vibrational analysis by vibrational quasi-degenerate perturbation theory (VQDPT) successfully reproduced the anharmonic splitting, and confirmed the assignments.

  5. Fe3O4/γ-Fe2O3 nanoparticle multilayers deposited by the Langmuir-Blodgett technique for gas sensors application.

    PubMed

    Capone, S; Manera, M G; Taurino, A; Siciliano, P; Rella, R; Luby, S; Benkovicova, M; Siffalovic, P; Majkova, E

    2014-02-01

    Fe3O4/γ-Fe2O3 nanoparticles (NPs) based thin films were used as active layers in solid state resistive chemical sensors. NPs were synthesized by high temperature solution phase reaction. Sensing NP monolayers (ML) were deposited by Langmuir-Blodgett (LB) techniques onto chemoresistive transduction platforms. The sensing ML were UV treated to remove NP insulating capping. Sensors surface was characterized by scanning electron microscopy (SEM). Systematic gas sensing tests in controlled atmosphere were carried out toward NO2, CO, and acetone at different concentrations and working temperatures of the sensing layers. The best sensing performance results were obtained for sensors with higher NPs coverage (10 ML), mainly for NO2 gas showing interesting selectivity toward nitrogen oxides. Electrical properties and conduction mechanisms are discussed.

  6. Generation and characterization of plasma channels in gas puff targets using soft X-ray radiography technique

    SciTech Connect

    Wachulak, P. W. Bartnik, A.; Jarocki, R.; Fok, T.; Węgrzyński, Ł.; Kostecki, J.; Szczurek, M.; Jabczyński, J.; Fiedorowicz, H.

    2014-10-15

    We present our recent results of a formation and characterization of plasma channels in elongated krypton and xenon gas puff targets. The study of their formation and temporal expansion was carried out using a combination of a soft X-ray radiography (shadowgraphy) and pinhole camera imaging. Two high-energy short laser pulses were used to produce the channels. When a pumping laser pulse was shaped into a line focus, using cylindrical and spherical lenses, the channels were not produced because much smaller energy density was deposited in the gas puff target. However, when a point focus was obtained, using just a spherical lens, the plasma channels appeared. The channels were up to 9 mm in length, had a quite uniform density profile, and expanded in time with velocities of about 2 cm/μs.

  7. Three-dimensional measurement of a gas flow temperature field using far-infrared band CT techniques

    NASA Astrophysics Data System (ADS)

    Zhang, Zhimin; Wang, Peng; Li, Shujing

    2014-01-01

    Emission spectral tomography (EST) can be utilized to reconstruct three-dimensional (3D) physical parameter distributions of gas flow fields. Mostly, the radiant energy of the visual and near-infrared bands is received by a video camera in EST, so it is difficult to examine a low/medium-temperature gas flow field by normal EST. However, the far-infrared radiant energy of a low/medium-temperature gas flow field is strong enough to be received by a far-infrared detector. Based on EST, a far-infrared band computed tomography (FICT) approach is proposed that focuses on far-infrared spectral emission and band emission tomography. Both low- and medium-temperature blackbody furnaces were adopted to calibrate the relation between infrared thermal image intensity and radiant exitance. The 3D temperature reconstruction of an alcohol blow lamp was carried out. According to the results of multiple measurements, the relative error of the FICT approach is less than 20%. The experimental results prove the feasibility of the FICT approach.

  8. Evaluation of optimum roughage to concentrate ratio in maize stover based complete rations for efficient microbial biomass production using in vitro gas production technique

    PubMed Central

    Reddy, Y. Ramana; Kumari, N. Nalini; Monika, T.; Sridhar, K.

    2016-01-01

    Aim: A study was undertaken to evaluate the optimum roughage to concentrate ratio in maize stover (MS) based complete diets for efficient microbial biomass production (EMBP) using in vitro gas production technique. Materials and Methods: MS based complete diets with roughage to concentrate ratio of 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, and 30:70 were formulated, and 200 mg of oven-dried sample was incubated in water bath at 39°C along with media (rumen liquor [RL] - buffer) in in vitro gas syringes to evaluate the gas production. The gas produced was recorded at 8 and 24 h of incubation. In vitro organic matter digestibility (IVOMD), metabolizable energy (ME), truly digestible organic matter (TDOM), partitioning factor (PF), and EMBP were calculated using appropriate formulae. Ammonia nitrogen and total volatile fatty acids (TVFAs) production were analyzed in RL fluid-media mixture after 24 h of incubation. Results: In vitro gas production (ml) at 24 h incubation, IVOMD, ME, TDOM, TVFA concentration, and ammonia nitrogen production were increased (p<0.01) in proportion to the increase in the level of concentrate in the diet. Significantly (p<0.01) higher PF and EMBP was noticed in total mixed ration with roughage to concentrate ratio of 60:40 and 50:50 followed by 70:30 and 40:60. Conclusion: Based on the results, it was concluded that the MS can be included in complete rations for ruminants at the level of 50-60% for better microbial biomass synthesis which in turn influences the performance of growing sheep. PMID:27397985

  9. Quantification of OH and HO2 radicals during the low-temperature oxidation of hydrocarbons by Fluorescence Assay by Gas Expansion technique

    PubMed Central

    Blocquet, Marion; Schoemaecker, Coralie; Amedro, Damien; Herbinet, Olivier; Battin-Leclerc, Frédérique; Fittschen, Christa

    2013-01-01

    •OH and •HO2 radicals are known to be the key species in the development of ignition. A direct measurement of these radicals under low-temperature oxidation conditions (T = 550–1,000 K) has been achieved by coupling a technique named fluorescence assay by gas expansion, an experimental technique designed for the quantification of these radicals in the free atmosphere, to a jet-stirred reactor, an experimental device designed for the study of low-temperature combustion chemistry. Calibration allows conversion of relative fluorescence signals to absolute mole fractions. Such radical mole fraction profiles will serve as a benchmark for testing chemical models developed to improve the understanding of combustion processes. PMID:24277836

  10. A novel fully automated on-line coupled liquid chromatography-gas chromatography technique used for the determination of organochlorine pesticide residues in tobacco and tobacco products.

    PubMed

    Qi, Dawei; Fei, Ting; Sha, Yunfei; Wang, Leijun; Li, Gang; Wu, Da; Liu, Baizhan

    2014-12-29

    In this study, a novel fully automated on-line coupled liquid chromatography-gas chromatography (LC-GC) technique was reported and applied for the determination of organochlorine pesticide residues (OCPs) in tobacco and tobacco products. Using a switching valve to isolate the capillary pre-column and the analytical column during the solvent evaporation period, the LC solvent can be completely removed and prevented from reaching the GC column and the detector. The established method was used to determinate the OCPs in tobacco samples. By using Florisil SPE column and employing GPC technique, polarity impurities and large molecule impurities were removed. A dynamic range 1-100ng/mL was achieved with detection limits from 1.5 to 3.3μg/kg. The method exhibited good repeatability and recoveries. This technology may provide an alternative way for trace analysis of complex samples.

  11. A Dual-Line Detection Rayleigh Scattering Diagnostic Technique for the Combustion of Hydrocarbon Fuels and Filtered UV Rayleigh Scattering for Gas Velocity Measurements

    NASA Technical Reports Server (NTRS)

    Otugen, M. Volkan

    1997-01-01

    Non-intrusive techniques for the dynamic measurement of gas flow properties such as density, temperature and velocity, are needed in the research leading to the development of new generation high-speed aircraft. Accurate velocity, temperature and density data obtained in ground testing and in-flight measurements can help understand the flow physics leading to transition and turbulence in supersonic, high-altitude flight. Such non-intrusive measurement techniques can also be used to study combustion processes of hydrocarbon fuels in aircraft engines. Reliable, time and space resolved temperature measurements in various combustor configurations can lead to a better understanding of high temperature chemical reaction dynamics thus leading to improved modeling and better prediction of such flows. In view of this, a research program was initiated at Polytechnic University's Aerodynamics Laboratory with support from NASA Lewis Research Center through grants NAG3-1301 and NAG3-1690. The overall objective of this program has been to develop laser-based, non-contact, space- and time-resolved temperature and velocity measurement techniques. In the initial phase of the program a ND:YAG laser-based dual-line Rayleigh scattering technique was developed and tested for the accurate measurement of gas temperature in the presence of background laser glare. Effort was next directed towards the development of a filtered, spectrally-resolved Rayleigh/Mie scattering technique with the objective of developing an interferometric method for time-frozen velocity measurements in high-speed flows utilizing the uv line of an ND:YAG laser and an appropriate molecular absorption filter. This effort included both a search for an appropriate filter material for the 266 nm laser line and the development and testing of several image processing techniques for the fast processing of Fabry-Perot images for velocity and temperature information. Finally, work was also carried out for the development of

  12. Development and evaluation of gappy-POD as a data reconstruction technique for noisy PIV measurements in gas turbine combustors

    NASA Astrophysics Data System (ADS)

    Saini, Pankaj; Arndt, Christoph M.; Steinberg, Adam M.

    2016-07-01

    Low signal-to-noise in particle image velocimetry (PIV) measurements in systems such as high pressure gas turbine combustors can result in significant data gaps that negatively affect subsequent analysis. Here, gappy proper orthogonal decomposition (GPOD) is evaluated as a method of filling such missing data. Four GPOD methods are studied, including a new method that utilizes a median filter (MF) to adaptively select whether a local missing data point is updated after each iteration. These methods also are compared against local Kriging interpolation. The GPOD methods are tested using PIV data without missing vectors that were obtained in atmospheric pressure swirl flames. Parameters studied include the turbulence intensity, amount of missing data, and the amount of noise in the valid data. Two criteria to check for GPOD convergence also were investigated. The MF method filled in the missing data with the lowest error across all parameters tested, with approximately one-third the computational cost of Kriging. Furthermore, the accuracy of MF GPOD was relatively insensitive to the quality of the convergence criterion. Therefore, compared to the three other GPOD methods and Kriging interpolation, the MF GPOD method is an effective method for filling missing data in PIV measurements in the studied gas turbine combustor flows.

  13. Structural, nanomechanical, field emission and ammonia gas sensing properties of nitrogenated amorphous carbon films deposited by filtered anodic jet carbon arc technique.

    PubMed

    Tripathi, R K; Panwar, O S; Srivastava, A K; Rawal, Ishpal; Chockalingam, Sreekumar

    2014-07-01

    This paper reports the effect of substrate bias on the structural, nanomechanical, field emission and ammonia gas sensing properties of nitrogenated amorphous carbon films embedded with nanocrystallites (a-C: N: nc) deposited by a filtered anodic jet carbon arc (FAJCA) technique. The films are characterized by X-ray diffraction, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopic analysis, Raman spectroscopy, nanoindentation, field emission and ammonia gas sensing measurements. The properties of the films obtained are found to depend on the substrate bias. The maximum hardness (H)=42.7 GPa, elastic modulus (E)=330.4 GPa, plastic index parameter (H/E)=0.129 and elastic recovery (% ER)=74.4% have been obtained in a-C: N: nc films deposited at -60 V substrate bias which show the lowest ID/IG=0.43, emission threshold (ET)=4.9 V/µm accompanied with the largest emission current density (Jmax)=1 mA/cm(2) and field enhancement factor (β)=1805.6. The gas sensing behavior of the a-C: N: nc film has been tested by measuring the change in electrical resistance of the sample in ammonia environment at room temperature with the fast response and recovery time as 29 and 66.9s, respectively.

  14. A miniaturised electron ionisation time-of-flight mass spectrometer that uses a unique helium ion removal pulsing technique specifically for gas analysis.

    PubMed

    Qing, Jiang; Huang, Zhengxu; Zhang, Yan; Zhu, Hui; Tan, Guobin; Gao, Wei; Yang, Peng-yuan

    2013-06-21

    A miniaturised reflectron time-of-flight mass spectrometer combined with an electron ionisation ion source has been developed for the analysis of gases. An entirely new helium ion removal pulsing technique in this mass spectrometer is used to achieve an improved performance for the first time. The helium carrier gas, which enters into the source along with the gaseous sample, is simultaneously ionised and then orthogonally introduced into the time-of-fight mass analyser. Once the relatively light helium ions in the ion packet become extremely close to the reflectron plate (B-plate for short in this article), a modulated pulse is instantaneously applied on the B-plate and a negative reflectron voltage is set to the B-plate and lasts for a very short period, during which all the helium ions are directly bumped into the B-plate and subsequently removed. The helium ion removal pulsing technique can efficiently avoid saturation of the micro-channel plate caused by too many helium ions. A compact and durable instrument is designed, which has a mass resolving resolution greater than 400 FWHM for online gas analysis. The technology may also be further developed to remove other ions for TOF mass spectrometry.

  15. Comparison of mass spectrometry-based electronic nose and solid phase microextraction gas chromatography-mass spectrometry technique to assess infant formula oxidation.

    PubMed

    Fenaille, François; Visani, Piero; Fumeaux, René; Milo, Christian; Guy, Philippe A

    2003-04-23

    Two headspace techniques based on mass spectrometry detection (MS), electronic nose, and solid phase microextraction coupled to gas chromatography-mass spectrometry (SPME-GC/MS) were evaluated for their ability to differentiate various infant formula powders based on changes of their volatiles upon storage. The electronic nose gave unresolved MS fingerprints of the samples gas phases that were further submitted to principal component analysis (PCA). Such direct MS recording combined to multivariate treatment enabled a rapid differentiation of the infant formulas over a 4 week storage test. Although MS-based electronic nose advantages are its easy-to-use aspect and its meaningful data interpretation obtained with a high throughput (100 samples per 24 h), its greatest disadvantage is that the present compounds could not be identified and quantified. For these reasons, a SPME-GC/MS measurement was also investigated. This technique allowed the identification of saturated aldehydes as the main volatiles present in the headspace of infant milk powders. An isotope dilution assay was further developed to quantitate hexanal as a potential indicator of infant milk powder oxidation. Thus, hexanal content was found to vary from roughly 500 and 3500 microg/kg for relatively non-oxidized and oxidized infant formulas, respectively.

  16. Departures from local thermodynamic equilibrium in cutting arc plasmas derived from electron and gas density measurements using a two-wavelength quantitative Schlieren technique

    SciTech Connect

    Prevosto, L.; Mancinelli, B.; Artana, G.; Kelly, H.

    2011-03-15

    A two-wavelength quantitative Schlieren technique that allows inferring the electron and gas densities of axisymmetric arc plasmas without imposing any assumption regarding statistical equilibrium models is reported. This technique was applied to the study of local thermodynamic equilibrium (LTE) departures within the core of a 30 A high-energy density cutting arc. In order to derive the electron and heavy particle temperatures from the inferred density profiles, a generalized two-temperature Saha equation together with the plasma equation of state and the quasineutrality condition were employed. Factors such as arc fluctuations that influence the accuracy of the measurements and the validity of the assumptions used to derive the plasma species temperature were considered. Significant deviations from chemical equilibrium as well as kinetic equilibrium were found at elevated electron temperatures and gas densities toward the arc core edge. An electron temperature profile nearly constant through the arc core with a value of about 14000-15000 K, well decoupled from the heavy particle temperature of about 1500 K at the arc core edge, was inferred.

  17. Room Temperature Ammonia Gas Selectivity Studies On SnO2 Ultra Thin Film Prepared By Langmuir-Blodgett Technique

    NASA Astrophysics Data System (ADS)

    Choudhury, Sipra; Betty, C. A.; Girija, K. G.

    2010-12-01

    Interaction of various reducing and oxidizing gases with ultrathin SnO2 film at room temperature has been studied to investigate the selectivity of SnO2 film towards ammonia. SnO2 thin films show no response with O2, H2, CO, ethanol and methane. In presence of H2S and SO2 gases conductivity of the film increases where as film conductivity decreases with ammonia and NO2. With ammonia gas, the response is fast and >90% recovery takes place within 30 min where as with NO2_recovery is partial. The impedance study shows distinctly different frequency dependent responses towards NH3 and NO2 indicating specificity to ammonia in presence of NO2.

  18. Two techniques for temporal pulse compression in gas-filled hollow-core kagomé photonic crystal fiber.

    PubMed

    Mak, K F; Travers, J C; Joly, N Y; Abdolvand, A; Russell, P St J

    2013-09-15

    We demonstrate temporal pulse compression in gas-filled kagomé hollow-core photonic crystal fiber (PCF) using two different approaches: fiber-mirror compression based on self-phase modulation under normal dispersion, and soliton effect self-compression under anomalous dispersion with a decreasing pressure gradient. In the first, efficient compression to near-transform-limited pulses from 103 to 10.6 fs was achieved at output energies of 10.3 μJ. In the second, compression from 24 to 6.8 fs was achieved at output energies of 6.6 μJ, also with near-transform-limited pulse shapes. The results illustrate the potential of kagomé-PCF for postprocessing the output of fiber lasers. We also show that, using a negative pressure gradient, ultrashort pulses can be delivered directly into vacuum.

  19. Fourier transform-infrared spectroscopy and Gas chromatography-mass spectroscopy: reliable techniques for analysis of Parthenium mediated vermicompost.

    PubMed

    Rajiv, P; Rajeshwari, Sivaraj; Venckatesh, Rajendran

    2013-12-01

    Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectroscopy have been carried out to investigate the chemical composition of Parthenium mediated vermicompost. Four different concentrations of Parthenium and cow dung mixtures were vermicomposted using the earthworms (Eudrilus eugeniae). FT-IR spectra reveal the absence of Parthenin toxin (sesquiterpene lactone) and phenols in vermicompost which was obtained from high concentration of cow dung mixed treatments. GC-MS analysis shows no phenolic compounds and predominant level of intermediate metabolites such as 4,8,12,16-Tetramethylheptadecan-4-olide (7.61%), 2-Pentadecanone, 6,10,14-trimethyl- (5.29%) and Methyl 16-methyl-heptadecanoate (4.69%) during the vermicomposting process. Spectral results indicated that Parthenin toxin and phenols can be eradicated via vermicomposting if mixed with appropriate quantity of cow dung.

  20. Fourier transform-infrared spectroscopy and Gas chromatography-mass spectroscopy: Reliable techniques for analysis of Parthenium mediated vermicompost

    NASA Astrophysics Data System (ADS)

    Rajiv, P.; Rajeshwari, Sivaraj; Venckatesh, Rajendran

    2013-12-01

    Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectroscopy have been carried out to investigate the chemical composition of Parthenium mediated vermicompost. Four different concentrations of Parthenium and cow dung mixtures were vermicomposted using the earthworms (Eudrilus eugeniae). FT-IR spectra reveal the absence of Parthenin toxin (sesquiterpene lactone) and phenols in vermicompost which was obtained from high concentration of cow dung mixed treatments. GC-MS analysis shows no phenolic compounds and predominant level of intermediate metabolites such as 4,8,12,16-Tetramethylheptadecan-4-olide (7.61%), 2-Pentadecanone, 6,10,14-trimethyl- (5.29%) and Methyl 16-methyl-heptadecanoate (4.69%) during the vermicomposting process. Spectral results indicated that Parthenin toxin and phenols can be eradicated via vermicomposting if mixed with appropriate quantity of cow dung.

  1. Strategies and methodologies to develop techniques for computer-assisted analysis of gas phase formation during altitude decompression

    NASA Technical Reports Server (NTRS)

    Powell, Michael R.; Hall, W. A.

    1993-01-01

    It would be of operational significance if one possessed a device that would indicate the presence of gas phase formation in the body during hypobaric decompression. Automated analysis of Doppler gas bubble signals has been attempted for 2 decades but with generally unfavorable results, except with surgically implanted transducers. Recently, efforts have intensified with the introduction of low-cost computer programs. Current NASA work is directed towards the development of a computer-assisted method specifically targeted to EVA, and we are most interested in Spencer Grade 4. We note that Spencer Doppler Grades 1 to 3 have increased in the FFT sonogram and spectrogram in the amplitude domain, and the frequency domain is sometimes increased over that created by the normal blood flow envelope. The amplitude perturbations are of very short duration, in both systole and diastole and at random temporal positions. Grade 4 is characteristic in the amplitude domain but with modest increases in the FFT sonogram and spectral frequency power from 2K to 4K over all of the cardiac cycle. Heart valve motion appears to characteristic display signals: (1) the demodulated Doppler signal amplitude is considerably above the Doppler-shifted blow flow signal (even Grade 4); and (2) demodulated Doppler frequency shifts are considerably greater (often several kHz) than the upper edge of the blood flow envelope. Knowledge of these facts will aid in the construction of a real-time, computer-assisted discriminator to eliminate cardiac motion artifacts. There could also exist perturbations in the following: (1) modifications of the pattern of blood flow in accordance with Poiseuille's Law, (2) flow changes with a change in the Reynolds number, (3) an increase in the pulsatility index, and/or (4) diminished diastolic flow or 'runoff.' Doppler ultrasound devices have been constructed with a three-transducer array and a pulsed frequency generator.

  2. Automated chamber technique for gaseous flux measurements: Evaluation of a photoacoustic infrared spectrometer-trace gas analyzer

    NASA Astrophysics Data System (ADS)

    Yamulki, S.; Jarvis, S. C.

    1999-03-01

    Experiments were made in order to evaluate the accuracy and sensitivity of a photoacoustic infrared trace gas analyzer (TGA) in conjunction with an automatic opening and closing chamber system developed for near-continuous (2 min intervals) soil gaseous flux measurements. Humidity interference tests on N2O, CH4, and CO2 concentrations measured by the TGA were carried out, and the results showed a linear interference, with correction factors of 3 × 10-5x, 1.9 × 10-3x and 4.4 × 10-3x(x = H2O vapor ppm), respectively. CO2 interference on N2O and CH4 signals were also linear, with average correction factors of 2.8 × 10-4x and 6 × 10-5 x (x = CO2 ppm), respectively. Laboratory intercomparisons between the TGA and GC measurements of N2O and CH4 standards showed good agreement (R2 > 0.993), indicating the accuracy of the TGA for measurement of these gases at concentrations up to 100 and 40 ppm N2O and CH4, respectively. The relatively rapid measurement time for up to five gases simultaneously in 2 min, linearity, and ease of operation of the TGA represent major advantages compared to gas chromatography (GC). The automated chamber system provides a continuous measurement of fluxes with minimum disturbance to the soil environment enclosed by the chamber and provides the means, for example, of quantifying diurnal variability. In situ measurements of N2O-N and CH4-C fluxes with a sensitivity <10 g ha-1 d-1 (11.6 ng m-2 s-1), as well as of CO2 and water vapor (H2O), can be measured by the TGA when used with the automated system, and fluxes at background levels (i.e., from unfertilized soils) can be determined.

  3. Estimating regional greenhouse gas fluxes: an uncertainty analysis of planetary boundary layer techniques and bottom-up inventories

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Lee, X.; Griffis, T. J.; Baker, J. M.; Xiao, W.

    2014-10-01

    Quantification of regional greenhouse gas (GHG) fluxes is essential for establishing mitigation strategies and evaluating their effectiveness. Here, we used multiple top-down approaches and multiple trace gas observations at a tall tower to estimate regional-scale GHG fluxes and evaluate the GHG fluxes derived from bottom-up approaches. We first applied the eddy covariance, equilibrium, inverse modeling (CarbonTracker), and flux aggregation methods using 3 years of carbon dioxide (CO2) measurements on a 244 m tall tower in the upper Midwest, USA. We then applied the equilibrium method for estimating CH4 and N2O fluxes with 1-month high-frequency CH4 and N2O gradient measurements on the tall tower and 1-year concentration measurements on a nearby tall tower, and evaluated the uncertainties of this application. The results indicate that (1) the flux aggregation, eddy covariance, the equilibrium method, and the CarbonTracker product all gave similar seasonal patterns of the regional CO2 flux (105-106 km2, but that the equilibrium method underestimated the July CO2 flux by 52-69%. (2) The annual budget varied among these methods from -54 to -131 g C-CO2 m-2 yr-1, indicating a large uncertainty in the annual CO2 flux estimation. (3) The regional CH4 and N2O emissions according to a top-down method were at least 6 and 2 times higher than the emissions from a bottom-up inventory (Emission Database for Global Atmospheric Research), respectively. (4) The global warming potentials of the CH4 and N2O emissions were equal in magnitude to the cooling benefit of the regional CO2 uptake. The regional GHG budget, including both biological and anthropogenic origins, is estimated at 7 ± 160 g CO2 equivalent m-2 yr-1.

  4. Identification of potential antioxidant compounds in the essential oil of thyme by gas chromatography with mass spectrometry and multivariate calibration techniques.

    PubMed

    Masoum, Saeed; Mehran, Mehdi; Ghaheri, Salehe

    2015-02-01

    Thyme species are used in traditional medicine throughout the world and are known for their antiseptic, antispasmodic, and antitussive properties. Also, antioxidant activity is one of the interesting properties of thyme essential oil. In this research, we aim to identify peaks potentially responsible for the antioxidant activity of thyme oil from chromatographic fingerprints. Therefore, the chemical compositions of hydrodistilled essential oil of thyme species from different regions were analyzed by gas chromatography with mass spectrometry and antioxidant activities of essential oils were measured by a 1,1-diphenyl-2-picrylhydrazyl radical scavenging test. Several linear multivariate calibration techniques with different preprocessing methods were applied to the chromatograms of thyme essential oils to indicate the peaks responsible for the antioxidant activity. These techniques were applied on data both before and after alignment of chromatograms with correlation optimized warping. In this study, orthogonal projection to latent structures model was found to be a good technique to indicate the potential antioxidant active compounds in the thyme oil due to its simplicity and repeatability.

  5. Development of a portable mass spectrometer characterized by discontinuous sample gas introduction, a low-pressure dielectric barrier discharge ionization source, and a vacuumed headspace technique.

    PubMed

    Kumano, Shun; Sugiyama, Masuyuki; Yamada, Masuyoshi; Nishimura, Kazushige; Hasegawa, Hideki; Morokuma, Hidetoshi; Inoue, Hiroyuki; Hashimoto, Yuichiro

    2013-05-21

    The present study has attempted to downscale a mass spectrometer in order to make it portable and enable onsite analysis with it. The development of a small mass spectrometer required the use of a compact pump whose displacement was small, decreasing the sensitivity of that spectrometer. To get high sensitivity with a small mass spectrometer, we have integrated novel techniques: a highly sensitive ionization source and efficient extraction of sample vapor. The low-pressure dielectric barrier discharge ionization (LP-DBDI) source made it possible to increase the conductance between the source and the mass analyzer, compared with ambient ionization sources, enhancing the efficiency of the ion transfer from the ionization source to the mass analyzer. We have also developed a vacuumed headspace method efficiently transporting the sample vapor to the ionization source. The sensitivity was further enhanced by also using a discontinuous sample gas introduction technique. A prototype portable mass spectrometer using those novel techniques was found to be sensitive enough to detect 0.1 ppm methamphetamine, 1 ppm amphetamine, 1 ppm 3,4-methylenedioxymethamphetamine, and 10 ppm cocaine in liquid.

  6. Field testing of fugitive dust control techniques at a uranium mill tailings pile - 1982 Field Test, Gas Hills, Wyoming.

    SciTech Connect

    Elmore, M.R.; Hartley, J.N.

    1983-12-01

    A field test was conducted on a uranium tailings pile to evaluate the effectiveness of 15 chemical stabilizers for control of fugitive dust from uranium mill tailings. A tailings pile at the Federal American Partners (FAP) Uranium Mill, Gas Hills, Wyoming, was used for the field test. Preliminary laboratory tests using a wing tunnel were conducted to select the more promising stabilizers for field testing. Fourteen of the chemical stabilizers were applied with a field spray system pulled behind a tractor; one--Hydro Mulch--was applied with a hydroseeder. A portable weather station and data logger were installed to record the weather conditions at the test site. After 1 year of monitoring (including three site visits), all of the stabilizers have degraded to some degree; but those applied at the manufacturers' recommended rate are still somewhat effective in reducing fugitive emissions. The following synthetic polymer emulsions appear to be the more effective stabilizers: Wallpol 40-133 from Reichold Chemicals, SP-400 from Johnson and March Corporation, and CPB-12 from Wen Don Corporation. Installed costs for the test plots ranged from $8400 to $11,300/ha; this range results from differences in stabilizer costs. Large-scale stabilization costs of the test materials are expected to range from $680 to $3600/ha based on FAP experience. Evaluation of the chemical stabilizers will continue for approximately 1 year. 2 references, 33 figures, 22 tables.

  7. Development of a new measurement technique for the investigation of end-gas autoignition and engine knock

    SciTech Connect

    Stiebels, B.; Schreiber, M.; Sadat Sakak, A.

    1996-09-01

    Two intensified CCD cameras were used in sequence to record the natural flame light during knocking combustion via a fused silica window, which was fitted to the cylinder head of a one-cylinder four-stroke SI-engine. This arrangement enabled acquisition of two images per cycle. While the first camera was triggered by the rapid rise of the cylinder pressure at the beginning of engine knock, the second camera was activated at a prescribed time of delay. Due to the high sensitivity of the intensified CCD cameras, extremely short exposure times of 100 to 250 ns proved to be sufficient. Extensive measurements for two different combustion chamber configurations were made at different engine speeds. The octane rating was varied by mixing the primary reference fuels i-octane and n-heptane in different proportions. The experiments clearly show that engine knock was locally induced by spontaneous ignition in the end-gas region rather than acceleration of the primary flame. The location and mode of the ensuing secondary propagation wave varied over a wide range, depending among other factors on octane rating and thermodynamic conditions. Flame velocities measured directly after the onset of knock indicate that the propagation mode of the reaction wave is somewhere between deflagration and developing detonation.

  8. Development of a gas chromatography-mass spectrometry technique to diagnose white snakeroot (Ageratina altissima) poisoning in a cow.

    PubMed

    Meyerholtz, Kimberly A; Burcham, Grant N; Miller, Margaret A; Wilson, Christina R; Hooser, Stephen B; Lee, Stephen T

    2011-07-01

    An 8-year-old, crossbred beef cow was referred to the Indiana Animal Disease Diagnostic Laboratory at Purdue University for a complete necropsy in October 2009. The cow was the sixth to die in a 7-day period. Affected cows were reportedly stumbling and became weak, excitable, and recumbent. Histologically, myonecrosis was severe in the skeletal muscles and mild in the heart and tongue. According to the submitter, exposure to a poisonous plant was suspected, and a plant specimen received from this case was identified as white snakeroot (Ageratina altissima). Using the white snakeroot specimen, a gas chromatography-mass spectrometry analytical method for the detection of tremetone and dehydrotremetone (2 components of white snakeroot) was developed. Both tremetone and dehydrotremetone were detected in the plant specimen. Dehydrotremetone was recovered from the liver, while neither component was recovered in the rumen content. In the past, because of the lack of standard reference material, the diagnosis of white snakeroot poisoning was based mainly on history of exposure and the presence of the plant in the rumen. The analytical method described herein can be used to document exposure to tremetone or dehydrotremetone in cases of suspected white snakeroot poisoning when coupled with the appropriate clinical signs and lesions. PMID:21908322

  9. Thermal degradation behavior of waste video cards using thermogravimetric analysis and pyrolysis gas chromatography/mass spectrometry techniques.

    PubMed

    Duan, Huabo; Li, Jinhui

    2010-05-01

    The thermal degradation characteristics of a printed circuit board assembly (PCBA), specifically video cards from waste computers, was studied using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). The video-card waste was dismantled into substrate, integrated circuits (ICs), and plastic slots for comparable investigation. The results by TGA revealed that the initial temperature at which degradation began was 300 degrees C for substrate, but it was 330 degrees C for ICs and plastic slots. For a given type of scrap, the initial temperature leading to degradation is the same under air and N2 atmosphere. However, the degradation rate was lower using air than N2 during the weight-loss stage. Further Py-GC/MS application revealed that pyrolysis products derived from substrate consisted mainly of acetone, bromotoluene, and phenol that came from the brominated epoxy resins present in substrate. Unlike substrate, the relative amounts of some products (e.g., phenol) were higher in the ICs, and cyclotetrasiloxane was released; these were released from the phenolic resins and Si mixture present in that type of waste. Benzoic acid, rather than acetone or phenol, was the main product released from plastic slots. It was proved that this scrap was a mixture of various polyesters, cracking of which predicatively generated aromatic products. The results will be useful in developing pyrolysis or starved-air incineration systems for thermosetting plastic and PCBA waste and helpful to control pollution during the treatment of this waste.

  10. Gas chromatography

    NASA Astrophysics Data System (ADS)

    Guiochon, Georges; Guillemin, Claude L.

    1990-11-01

    Gas chromatography is a powerful separation technique for gas and vapor mixtures. Combining separation and on-line detection permits accurate quantitative analysis of complex mixtures, including traces of compounds down to parts per trillions in some particular cases. The importance of gas chromatography in quality control and process control in the chemical and drug industry, in environmental pollution investigations and in clinical analysis is critical. The principles of the technique are discussed, the main components of a gas chromatograph are described and some idea of the importance of the applications is given.

  11. Structural, magnetic and gas sensing properties of nanosized copper ferrite powder synthesized by sol gel combustion technique

    NASA Astrophysics Data System (ADS)

    Sumangala, T. P.; Mahender, C.; Barnabe, A.; Venkataramani, N.; Prasad, Shiva

    2016-11-01

    Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300-800 °C and were either furnace cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2 emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800 °C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500 ppm ethanol in the case of a furnace cooled sample calcined at 800 °C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite.

  12. Rarefied gas dynamics: Theoretical and computational techniques; International Symposium, 16th, Pasadena, CA, July 10-16, 1988, Technical Papers

    SciTech Connect

    Muntz, E.P.; Weaver, D.P.; Campbell, D.H.

    1989-01-01

    Among the areas covered are kinetic theory, discrete kinetic theory, direct simulations, numerical techniques, and flowfields. The topics discussed include various problems for the Boltzman equation, such as initial and boundary values, the collision integral, and stationary flows. Discrete-velocity gases, molecular dynamics calculations of transport properties, and multispeed cellular automation are among the topics discussed within the framework of the discrete kinetic theory. Attention is given to numerical methods in rarefied gasdynamics, statistical fluctuations in Monte Carlo calculations, and rarefield normal shocks. Emphasis is placed on numerical solutions for the Boltzman equation, as well as on Monte Carlo solutions. Three-dimensional flows, hypersonic flows, transitional flows, and wake flows are also analyzed.

  13. Estimation of spatial apportionment of greenhouse gas emissions for the UK using boundary layer measurements and inverse modelling technique

    NASA Astrophysics Data System (ADS)

    Polson, D.; Fowler, D.; Nemitz, E.; Skiba, U.; McDonald, A.; Famulari, D.; Di Marco, C.; Simmons, I.; Weston, K.; Purvis, R.; Coe, H.; Manning, A. J.; Webster, H.; Harrison, M.; O'Sullivan, D.; Reeves, C.; Oram, D.

    2011-02-01

    A technique is described to independently validate the national emission inventories produced using the methodology of the Intergovernmental Panel on Climate Change (IPCC). A boundary layer budget approach is applied to the United Kingdom and an inverse modelling technique is used to derive total and spatial apportionment of emissions for CO, CO 2, CH 4, N 2O, HFC-134a, HCFC-141b, HCFC-142b and HCFC-22. During the summer of 2005 and September 2006 an aircraft circumnavigating the UK was used to collect data upwind and downwind of the UK coast. The concentration measurements were inverted to produce mapped emissions of the UK. The modelled overall CO flux (2900 ± 107 kt yr -1) and spatial apportionment throughout the UK are remarkably consistent with the official UK NAEI (National Atmospheric Emission Inventory) inventory. The CO 2 total emissions (620 ± 105 Mt yr -1) and spatial apportionment are also close to the NAEI. However for N 2O and CH 4, the estimated annual fluxes, 500 ± 370 kt yr -1 and 3500 (range 0-8000 kt yr -1) respectively, are larger than the NAEI albeit with significant uncertainty. Emissions of four halocarbon compounds were also calculated with total emissions of 3.1 ± 0.4 kt yr -1 for HFC-134a, 0.9 ± 0.6 kt yr -1 for HCFC-141b, 0.56 ± 0.2 kt yr -1 for HCFC-142b and 3.8 ± 1.0 kt yr -1 for HCFC-22 consistent with other published data.

  14. Aortic distensibility is reduced during intense lower body negative pressure and is related to low frequency power of systolic blood pressure.

    PubMed

    Phillips, Aaron A; Bredin, Shannon S D; Cote, Anita T; Drury, C Taylor; Warburton, Darren E R

    2013-03-01

    As sympathetic activity approximately doubles during intense lower body negative pressure (LBNP) of -60 mmHg or greater, we examined the relationship between surrogate markers of sympathetic activation and central arterial distensibility during severe LBNP. Eight participants were exposed to progressive 8-min stages of LBNP of increasing intensity (-20, -40, -60, and -80 mmHg), while recording carotid-femoral pulse wave velocity (cPWV), stroke volume (SV), heart rate, and beat-by-beat blood pressure. The spectral power of low frequency oscillations in SBP (SBP(LF)) was used as a surrogate indicator of sympathetically modulated vasomotor modulation. Total arterial compliance (C) was calculated as C = SV/pulse pressure. Both cPWV and C were compared between baseline, 50 % of the maximally tolerated LBNP stage (LBNP(50)), and the maximum fully tolerated stage of LBNP (LBNP(max)). No change in mean arterial pressure (MAP) occurred over LBNP. An increase in cPWV (6.5 ± 2.2; 7.2 ± 1.4; 9.0 ± 2.5 m/s; P = 0.004) occurred during LBNP(max). Over progressive LBNP, SBP(LF) increased (8.5 ± 4.6; 9.3 ± 5.8; 16.1 ± 12.9 mmHg(2); P = 0.04) and C decreased significantly (18.3 ± 6.8; 14.3 ± 4.1; 11.6 ± 4.8 ml/mmHg × 10; P = 0.03). The mean correlation (r) between cPWV and SBP(LF) was 0.9 ± 0.03 (95 % CI 0.79-0.99). Severe LBNP increased central stiffness and reduced total arterial compliance. It appears that increased sympathetic vasomotor tone during LBNP is associated with reduced aortic distensibility in the absence of changes in MAP.

  15. Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric datasets

    NASA Astrophysics Data System (ADS)

    Wyche, K. P.; Monks, P. S.; Smallbone, K. L.; Hamilton, J. F.; Alfarra, M. R.; Rickard, A. R.; McFiggans, G. B.; Jenkin, M. E.; Bloss, W. J.; Ryan, A. C.; Hewitt, C. N.; MacKenzie, A. R.

    2015-01-01

    Highly non-linear dynamical systems, such as those found in atmospheric chemistry, necessitate hierarchical approaches to both experiment and modeling in order, ultimately, to identify and achieve fundamental process-understanding in the full open system. Atmospheric simulation chambers comprise an intermediate in complexity, between a classical laboratory experiment and the full, ambient system. As such, they can generate large volumes of difficult-to-interpret data. Here we describe and implement a chemometric dimension reduction methodology for the deconvolution and interpretation of complex gas- and particle-phase composition spectra. The methodology comprises principal component analysis (PCA), hierarchical cluster analysis (HCA) and positive least squares-discriminant analysis (PLS-DA). These methods are, for the first time, applied to simultaneous gas- and particle-phase composition data obtained from a comprehensive series of environmental simulation chamber experiments focused on biogenic volatile organic compound (BVOC) photooxidation and associated secondary organic aerosol (SOA) formation. We primarily investigated the biogenic SOA precursors isoprene, α-pinene, limonene, myrcene, linalool and β-caryophyllene. The chemometric analysis is used to classify the oxidation systems and resultant SOA according to the controlling chemistry and the products formed. Furthermore, a holistic view of results across both the gas- and particle-phases shows the different SOA formation chemistry, initiating in the gas-phase, proceeding to govern the differences between the various BVOC SOA compositions. The results obtained are used to describe the particle composition in the context of the oxidized gas-phase matrix. An extension of the technique, which incorporates into the statistical models data from anthropogenic (i.e. toluene) oxidation and "more realistic" plant mesocosm systems, demonstrates that such an ensemble of chemometric mapping has the potential to be

  16. Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric data sets

    NASA Astrophysics Data System (ADS)

    Wyche, K. P.; Monks, P. S.; Smallbone, K. L.; Hamilton, J. F.; Alfarra, M. R.; Rickard, A. R.; McFiggans, G. B.; Jenkin, M. E.; Bloss, W. J.; Ryan, A. C.; Hewitt, C. N.; MacKenzie, A. R.

    2015-07-01

    Highly non-linear dynamical systems, such as those found in atmospheric chemistry, necessitate hierarchical approaches to both experiment and modelling in order to ultimately identify and achieve fundamental process-understanding in the full open system. Atmospheric simulation chambers comprise an intermediate in complexity, between a classical laboratory experiment and the full, ambient system. As such, they can generate large volumes of difficult-to-interpret data. Here we describe and implement a chemometric dimension reduction methodology for the deconvolution and interpretation of complex gas- and particle-phase composition spectra. The methodology comprises principal component analysis (PCA), hierarchical cluster analysis (HCA) and positive least-squares discriminant analysis (PLS-DA). These methods are, for the first time, applied to simultaneous gas- and particle-phase composition data obtained from a comprehensive series of environmental simulation chamber experiments focused on biogenic volatile organic compound (BVOC) photooxidation and associated secondary organic aerosol (SOA) formation. We primarily investigated the biogenic SOA precursors isoprene, α-pinene, limonene, myrcene, linalool and β-caryophyllene. The chemometric analysis is used to classify the oxidation systems and resultant SOA according to the controlling chemistry and the products formed. Results show that "model" biogenic oxidative systems can be successfully separated and classified according to their oxidation products. Furthermore, a holistic view of results obtained across both the gas- and particle-phases shows the different SOA formation chemistry, initiating in the gas-phase, proceeding to govern the differences between the various BVOC SOA compositions. The results obtained are used to describe the particle composition in the context of the oxidised gas-phase matrix. An extension of the technique, which incorporates into the statistical models data from anthropogenic (i

  17. Simultaneous determination of sorbic and benzoic acids in milk products using an optimised microextraction technique followed by gas chromatography.

    PubMed

    Abedi, Abdol-Samad; Mohammadi, Abdorreza; Azadniya, Ebrahim; Mortazavian, Amir Mohammad; Khaksar, Ramin

    2014-01-01

    A rapid and reliable method for direct determination of sorbic and benzoic acids in milk products was developed by dispersive liquid-liquid microextraction (DLLME) and gas chromatography with flame ionisation detector (GC-FID). A response surface methodology (RSM) based on a central composite design (CCD) was applied for optimisation of the main variables, such as volume of extraction and dispersive solvents, pH and salt effect. The primary extraction of sorbic and benzoic acids were performed in 8 mL NaOH (0.1 M) in a closed-vessel system. Carrez solutions (potassium hexaferrocyanide and zinc acetate) were used for protein sedimentation. The best simultaneous extraction efficiency was identified using acetone and 1-octanal as dispersive and extraction solvents, respectively. For DLLME, central composite design resulted in the optimised values of microextraction parameters as follows: 475 µL of dispersive and 60 µL of extraction solvents, 2 g NaCl at pH 2.5. Under optimum conditions, the calibration curve was linear over the range 0.1-50 μg mL(-1) and the square of correlation coefficient (R(2)) was 0.9992 for sorbic acid and 0.9994 for benzoic acid. Relative standard deviation (RSD %) was 6.1% and 3.1% (n = 5) for sorbic and benzoic acids, respectively. Limits of detection were 150 ng g(-1) for sorbic acid and 140 ng g(-1) for benzoic acid and recoveries were 88% and 103.7% respectively. Good reproducibility (RSD %), short extraction time and no matrix interference were advantages of the proposed method which was successfully applied to the determination of sorbic and benzoic acids in milk products. PMID:24397823

  18. A Novel Optimization Technique to Improve Gas Recognition by Electronic Noses Based on the Enhanced Krill Herd Algorithm.

    PubMed

    Wang, Li; Jia, Pengfei; Huang, Tailai; Duan, Shukai; Yan, Jia; Wang, Lidan

    2016-01-01

    An electronic nose (E-nose) is an intelligent system that we will use in this paper to distinguish three indoor pollutant gases (benzene (C₆H₆), toluene (C₇H₈), formaldehyde (CH₂O)) and carbon monoxide (CO). The algorithm is a key part of an E-nose system mainly composed of data processing and pattern recognition. In this paper, we employ support vector machine (SVM) to distinguish indoor pollutant gases and two of its parameters need to be optimized, so in order to improve the performance of SVM, in other words, to get a higher gas recognition rate, an effective enhanced krill herd algorithm (EKH) based on a novel decision weighting factor computing method is proposed to optimize the two SVM parameters. Krill herd (KH) is an effective method in practice, however, on occasion, it cannot avoid the influence of some local best solutions so it cannot always find the global optimization value. In addition its search ability relies fully on randomness, so it cannot always converge rapidly. To address these issues we propose an enhanced KH (EKH) to improve the global searching and convergence speed performance of KH. To obtain a more accurate model of the krill behavior, an updated crossover operator is added to the approach. We can guarantee the krill group are diversiform at the early stage of iterations, and have a good performance in local searching ability at the later stage of iterations. The recognition results of EKH are compared with those of other optimization algorithms (including KH, chaotic KH (CKH), quantum-behaved particle swarm optimization (QPSO), particle swarm optimization (PSO) and genetic algorithm (GA)), and we can find that EKH is better than the other considered methods. The research results verify that EKH not only significantly improves the performance of our E-nose system, but also provides a good beginning and theoretical basis for further study about other improved krill algorithms' applications in all E-nose application areas. PMID

  19. A Novel Optimization Technique to Improve Gas Recognition by Electronic Noses Based on the Enhanced Krill Herd Algorithm

    PubMed Central

    Wang, Li; Jia, Pengfei; Huang, Tailai; Duan, Shukai; Yan, Jia; Wang, Lidan

    2016-01-01

    An electronic nose (E-nose) is an intelligent system that we will use in this paper to distinguish three indoor pollutant gases (benzene (C6H6), toluene (C7H8), formaldehyde (CH2O)) and carbon monoxide (CO). The algorithm is a key part of an E-nose system mainly composed of data processing and pattern recognition. In this paper, we employ support vector machine (SVM) to distinguish indoor pollutant gases and two of its parameters need to be optimized, so in order to improve the performance of SVM, in other words, to get a higher gas recognition rate, an effective enhanced krill herd algorithm (EKH) based on a novel decision weighting factor computing method is proposed to optimize the two SVM parameters. Krill herd (KH) is an effective method in practice, however, on occasion, it cannot avoid the influence of some local best solutions so it cannot always find the global optimization value. In addition its search ability relies fully on randomness, so it cannot always converge rapidly. To address these issues we propose an enhanced KH (EKH) to improve the global searching and convergence speed performance of KH. To obtain a more accurate model of the krill behavior, an updated crossover operator is added to the approach. We can guarantee the krill group are diversiform at the early stage of iterations, and have a good performance in local searching ability at the later stage of iterations. The recognition results of EKH are compared with those of other optimization algorithms (including KH, chaotic KH (CKH), quantum-behaved particle swarm optimization (QPSO), particle swarm optimization (PSO) and genetic algorithm (GA)), and we can find that EKH is better than the other considered methods. The research results verify that EKH not only significantly improves the performance of our E-nose system, but also provides a good beginning and theoretical basis for further study about other improved krill algorithms’ applications in all E-nose application areas. PMID

  20. Synthesis and characterization of nano-structured molybdenum-iron intermetallics by gas-solid reaction technique

    NASA Astrophysics Data System (ADS)

    El-Geassy, A. A.; Seetheraman, S.

    2016-03-01

    Ammonium molybdate and ferrous oxalate were used for the synthesis of nano-structured Mo-Fe intermetallics. Co-precipitation technique was applied to produce Mo/Fe precursors containing 58/42, 72/28 and 30/70 mass% respectively. The different phases formed were identified by XRD. The macro- and microstructures were microscopically examined by Reflected Light Microscope (RLM) and Scanning Electron Microscope (SEM) coupled with Electron Dispersion Spectroscopy (EDS). TG-DTA-DSC technique was applied to follow up the behavior of precursors up to 900oC (10K/min.). Endothermic peaks were detected at 97.8, 196.9 and 392.7oC due to the decomposition reactions to produce MoO3 and Fe2O3. The exothermic peak resulted at 427.8oC is due to the solid state reaction between these oxides to form Fe2(MoO4)3. Precursors were isothermally reduced at 600-850oC in a flow of purified H2 and the O2-weight loss from the reduction reactions was continuously recorded as a function of time. The isothermal reduction behavior of precursors was investigated. The structures of reduced products and the different phases formed were investigated and correlated with the reduction conditions. At >60% reduction extents, Fe2(MoO4)3] phase was first reduced to Fe2MoO3O8 before the formation of FeMo, while FeMoO4 and MoO2 were reduced to FeMo and Mo. In precursors containing higher content of Fe2O3, FeMo, Fe3Mo and Fe phases were produced. The visual observation of reduced samples showed that the volume was gradually shrinking with rise in temperature up to 800oC and beyond which a measurable swelling was observed reaching about 170% at 900oC.

  1. CuO SnO2 element as hydrogen sulfide gas sensor prepared by a sequential electron beam evaporation technique

    NASA Astrophysics Data System (ADS)

    Kumar, Rajesh; Khanna, Atul; Tripathi, Pragya; Nandedkar, R. V.; Potdar, S. R.; Chaudhari, S. M.; Bhatti, S. S.

    2003-10-01

    CuO-SnO2 thin film elements were prepared by sequential evaporation of Sn and Cu metals in high vacuum conditions by an electron beam evaporation technique and subsequent oxidation of the metallic bilayer under flowing oxygen conditions. The electrical properties of the thin film element were studied by a two probe method in the temperature range 110-220°C. On exposing the CuO-SnO2 thin films to a H2S-air mixture, it is observed that the resistance decreases by several thousand times. The H2S sensitivity of the thin film element was measured at three sensor operating temperatures. While the sensitivity decreased with an increase in temperature, both the response and recovery times improved with increasing temperature. The sensor element was selective to H2S gas and did not show any sensitivity to hydrogen and ethanol. The extraordinarily high sensitivity to H2S gas is attributed to the outstanding promoter action of CuO along with the unique porous structure of the thin film element as revealed by scanning electron microscopy studies.

  2. Assessment of inhalation and ingestion doses from exposure to radon gas using passive and active detecting techniques

    SciTech Connect

    Ismail, A. H.; Jafaar, M. S.

    2011-07-01

    The aim of this study was to assess an environmental hazard of radon exhalation rate from the samples of soil and drinking water in selected locations in Iraqi Kurdistan, passive (CR-39NTDs) and active (RAD7) detecting techniques has been employed. Long and short term measurements of emitted radon concentrations were estimated for 124 houses. High and lower radon concentration in soil samples was in the cities of Hajyawa and Er. Tyrawa, respectively. Moreover, for drinking water, high and low radon concentration was in the cities of Similan and Kelak, respectively. A comparison between our results with that mentioned in international reports had been done. Average annual dose equivalent to the bronchial epithelium, stomach and whole body in the cities of Kelak and Similan are estimated, and it was varied from 0.04{+-}0.01 mSv to 0.547{+-}0.018 mSv, (2.832{+-}0.22)x10{sup -5} to (11.972{+-}2.09)x10{sup -5} mSv, and (0.056 {+-}0.01) x10{sup -5} to (0.239{+-}0.01)x10{sup -5} mSv, respectively. This indicated that the effects of dissolved radon on the bronchial epithelium are much than on the stomach and whole body. (authors)

  3. Synergistic Effects of a Combination of Cr2O3-Functionalization and UV-Irradiation Techniques on the Ethanol Gas Sensing Performance of ZnO Nanorod Gas Sensors.

    PubMed

    Park, Sunghoon; Sun, Gun-Joo; Jin, Changhyun; Kim, Hyoun Woo; Lee, Sangmin; Lee, Chongmu

    2016-02-01

    There have been very few studies on the effects of combining two or more techniques on the sensing performance of nanostructured sensors. Cr2O3-functionalized ZnO nanorods were synthesized using carbothermal synthesis involving the thermal evaporation of a mixture of ZnO and graphite powders followed by a solvothermal process for Cr2O3-functionalization. The ethanol gas-sensing properties of multinetworked pristine and Cr2O3-functionalized ZnO nanorod sensors under UV illumination were examined to determine the effects of combining Cr2O3-ZnO heterostructure formation and UV irradiation on the gas-sensing properties of ZnO nanorods. The responses of the pristine and Cr2O3-functionalized ZnO nanorod sensors to 200 ppm of ethanol at room temperature by UV illumination at 2.2 mW/cm(2) were increased by 3.8 and 7.7 times, respectively. The Cr2O3-functionalized ZnO nanorod sensor also showed faster response/recovery and better selectivity than those of the pristine ZnO nanorod sensor at the same ethanol concentration. This result suggests that a combination heterostructure formation and UV irradiation had a synergistic effect on the gas-sensing properties of the sensor. The synergistic effect might be attributed to the catalytic activity of Cr2O3 for ethanol oxidation as well as to the increased change in conduction channel width accompanying adsorption and desorption of ethanol under UV illumination due to the presence of Cr2O3 nanoparticles in the Cr2O3-functionalized ZnO nanorod sensor. PMID:26751000

  4. Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hui-Hui, Xia; Rui-Feng, Kan; Jian-Guo, Liu; Zhen-Yu, Xu; Ya-Bai, He

    2016-06-01

    An improved algebraic reconstruction technique (ART) combined with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional (2D) distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid, and after that point, the number of projection rays has little influence on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method. In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed, and the capability of this new method is evaluated by using appropriate assessment parameters. By using this new approach, not only the concentration reconstruction accuracy is greatly improved, but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation. Finally, a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles. This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205151), the National Key Scientific Instrument and Equipment Development Project of China (Grant

  5. Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hui-Hui, Xia; Rui-Feng, Kan; Jian-Guo, Liu; Zhen-Yu, Xu; Ya-Bai, He

    2016-06-01

    An improved algebraic reconstruction technique (ART) combined with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional (2D) distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid, and after that point, the number of projection rays has little influence on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method. In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed, and the capability of this new method is evaluated by using appropriate assessment parameters. By using this new approach, not only the concentration reconstruction accuracy is greatly improved, but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation. Finally, a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles. This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205151), the National Key Scientific Instrument and Equipment Development Project of China (Grant

  6. Investigation of the characteristics of biofilms grown in gas-phase biofilters with and without ozone injection by CLSM technique.

    PubMed

    Saingam, Prakit; Xi, Jinying; Xu, Yang; Hu, Hong-Ying

    2016-02-01

    Recently, ozone injection technique was developed as a novel biomass control method to reduce bed clogging in biofilters treating volatile organic compounds (VOCs). However, the effects of ozone on the characteristics of biofilms are still unknown. In this study, two identical lab-scale biofilters treating gaseous toluene were operated in parallel except that one was continuously injected with 200 mg/m(3) ozone. Four glass slides were placed inside each biofilter on day 57 and then were taken out sequentially after 1, 2, 4, and 6 weeks of cultivation. The biofilms grown on the glass slides were stained by the ViaGram™ Red + Bacterial Gram Stain and Viability Kit and observed through the confocal laser scanning microscopy (CLSM). According to the CLSM images of 1, 2, and 4 weeks, the ozonated biofilm was significantly thinner than the control biofilm, which demonstrated that ozone could effectively control the biomass in the biofilter. For the biofilter without ozone injection, the ratios of viable cells (0.51~0.89) and the ratios of Gram-positive bacteria (0.22~0.57) both decreased within 4 weeks of cultivation. The CLSM image analysis results also demonstrated that a continuous injection of 200 mg/m(3) ozone was able to significantly enhance the ratio of viable cells to 0.77~0.97 and allow the dominance of Gram-positive bacteria in the biofilms with the ratio 0.46~0.88 instead of Gram-negative bacteria. For the 6-week samples, the biofilm thickness of the control system was reduced significantly which indicated the detachment of accumulated biofilms might occur in the samples without ozone.

  7. Theoretical approach for enhanced mass transfer effects in duct flue gas desulfurization processes. Topical report for Task 4, Novel techniques

    SciTech Connect

    Jozewicz, Wojciech; Rochelle, G.T.

    1991-09-17

    Novel techniques designed for the enhancement of Ca(OH){sub 2} utilization in dry-sorbent injection (DSI) and duct-spray drying (DSD) were investigated in the Long Time Differential Reactor (LTDR), Short Time Differential Reactor (STDR), and 50-cfm pilot plant. At 2000-ppm SO{sub 2} and 60 percent relative humidity, the presence of up to 30-percent initial free moisture significantly increased sorbent reactivity with SO{sub 2}, compared to sorbent with equilibrium amount of moisture. The conversion decreased when the initial free moisture increased beyond 30--50 percent. The initial free moisture content and corresponding level of maximum sorbent conversion with SO{sub 2} varied with the surface area of the sorbent. Sorbent moisture capacity tests indicated that agglomeration of damp calcium silicate sorbent was a function of sorbent pore volume. Critical moisture content was increasing with specific surface area. Very little improvement in SO{sub 2} removal was obtained by DSI recycle operation downstream of humidification. Significant enhancement was achieved by DSI recycle upstream of humidification. Grinding of DSI solids with and without fly ash resulted in significant increase of surface area and pore volume and resulting reactivity with SO{sub 2}. Organic buffer additives were tested as potential enhancement of Ca(OH){sub 2} utilization during the DSD process. Bench-scale results suggested that organic acids should be effective additives to enhance SO{sub 2} in slurry if SO{sub 2} absorption was controlled significantly by liquid film resistance. Pilot-plant tests did not demonstrate significant enhancement of Ca(OH){sub 2} conversion during spray drying as a result of buffer additives. Grinding of simulated DSD solids resulted in significant enhancement of Ca(OH){sub 2} reactivity with SO{sub 2}.

  8. Identification of phases in gas-atomised droplets by combination of neutron and X-ray diffraction techniques with atom probe tomography.

    PubMed

    Calvo-Dahlborg, M; Chambreland, S; Bao, C M; Quelennec, X; Cadel, E; Cuvilly, F; Dahlborg, U

    2009-04-01

    Powders of Al(68.5)Ni(31.5) alloy have been produced by gas atomisation and sieved in different grain size families. The resulting families have been analysed by combined neutron and X-ray diffraction in order to investigate the structure and identify the existing phases at the surface and in the bulk of the grains. The weight fraction of the identified phases (Al(3)Ni(2), Al(3)Ni and Al) has been estimated from a profile refinement with the FULLPROF computer codes. An additional phase was observed but could not be identified in the diffraction patterns. Starting from grains less than 5mum in diameter, samples have been shaped by annular focused ion beam into needles that were suitable for atom probe investigations. The structure and morphologies observed by different techniques are compared and discussed. It has also been possible to estimate the crystallite sizes and the strains corresponding to the different phases present in the powders from the refinement of the ND patterns. In addition to Al(3)Ni(2) and Al(3)Ni, a phase of composition close to the nominal one of the alloy was observed in the atom probe measurements. This phase could be one of the decagonal ones referred to in the literature. Small particles of composition close to Al(82)Ni(18) are attributed to the metastable Al(9)Ni(2) phase. The achieved conclusions demonstrate the complementarity of X-ray and neutron diffraction techniques and atom probe tomography to analyse complex structures.

  9. Multiclass pesticide analysis in fruit-based baby food: A comparative study of sample preparation techniques previous to gas chromatography-mass spectrometry.

    PubMed

    Petrarca, Mateus H; Fernandes, José O; Godoy, Helena T; Cunha, Sara C

    2016-12-01

    With the aim to develop a new gas chromatography-mass spectrometry method to analyze 24 pesticide residues in baby foods at the level imposed by established regulation two simple, rapid and environmental-friendly sample preparation techniques based on QuEChERS (quick, easy, cheap, effective, robust and safe) were compared - QuEChERS with dispersive liquid-liquid microextraction (DLLME) and QuEChERS with dispersive solid-phase extraction (d-SPE). Both sample preparation techniques achieved suitable performance criteria, including selectivity, linearity, acceptable recovery (70-120%) and precision (⩽20%). A higher enrichment factor was observed for DLLME and consequently better limits of detection and quantification were obtained. Nevertheless, d-SPE provided a more effective removal of matrix co-extractives from extracts than DLLME, which contributed to lower matrix effects. Twenty-two commercial fruit-based baby food samples were analyzed by the developed method, being procymidone detected in one sample at a level above the legal limit established by EU.

  10. Gas Chromatography.

    ERIC Educational Resources Information Center

    Karasek, Francis W.; And Others

    1984-01-01

    This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

  11. Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes

    NASA Astrophysics Data System (ADS)

    Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

    2015-04-01

    Volcanoes are a large source for several reactive atmospheric trace gases including sulphur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulphur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometers at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. Due to the lack of analytical approaches for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr etc.) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their specificationtheir species and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study, the first application of a 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated gas diffusion denuder (Huang and Hoffmann, 2008) on volcanic gases proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (Br2 and BrO(H)), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with bromine gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Choosing a flow rate of 500 mL-min-1 and a denuder length of 0.5 m a nearly quantitative collection efficiency was achieved. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography

  12. Adaptive Image-Guided Radiotherapy (IGRT) Eliminates the Risk of Biochemical Failure Caused by the Bias of Rectal Distension in Prostate Cancer Treatment Planning: Clinical Evidence

    SciTech Connect

    Park, Sean S.; Yan Di; McGrath, Samuel; Dilworth, Joshua T.; Liang Jian; Ye Hong; Krauss, Daniel J.; Martinez, Alvaro A.; Kestin, Larry L.

    2012-07-01

    Purpose: Rectal distension has been shown to decrease the probability of biochemical control. Adaptive image-guided radiotherapy (IGRT) corrects for target position and volume variations, reducing the risk of biochemical failure while yielding acceptable rates of gastrointestinal (GI)/genitourinary (GU) toxicities. Methods and Materials: Between 1998 and 2006, 962 patients were treated with computed tomography (CT)-based offline adaptive IGRT. Patients were stratified into low (n = 400) vs. intermediate/high (n = 562) National Comprehensive Cancer Network (NCCN) risk groups. Target motion was assessed with daily CT during the first week. Electronic portal imaging device (EPID) was used to measure daily setup error. Patient-specific confidence-limited planning target volumes (cl-PTV) were then constructed, reducing the standard PTV and compensating for geometric variation of the target and setup errors. Rectal volume (RV), cross-sectional area (CSA), and rectal volume from the seminal vesicles to the inferior prostate (SVP) were assessed on the planning CT. The impact of these volumetric parameters on 5-year biochemical control (BC) and chronic Grades {>=}2 and 3 GU and GI toxicity were examined. Results: Median follow-up was 5.5 years. Median minimum dose covering cl-PTV was 75.6 Gy. Median values for RV, CSA, and SVP were 82.8 cm{sup 3}, 5.6 cm{sup 2}, and 53.3 cm{sup 3}, respectively. The 5-year BC was 89% for the entire group: 96% for low risk and 83% for intermediate/high risk (p < 0.001). No statistically significant differences in BC were seen with stratification by RV, CSA, and SVP in quartiles. Maximum chronic Grades {>=}2 and 3 GI toxicities were 21.2% and 2.9%, respectively. Respective values for GU toxicities were 15.5% and 4.3%. No differences in GI or GU toxicities were noted when patients were stratified by RV. Conclusions: Incorporation of adaptive IGRT reduces the risk of geometric miss and results in excellent biochemical control that is

  13. Structural characterization and X-ray analysis by Williamson-Hall method for Erbium doped Aluminum Nitride nanoparticles, synthesized using inert gas condensation technique

    NASA Astrophysics Data System (ADS)

    Pandya, Sneha G.; Corbett, Joseph P.; Jadwisienczak, Wojciech M.; Kordesch, Martin E.

    2016-05-01

    We have synthesized AlN nanoparticles (NPs) doped in-situ with Er (AlN:Er) using inert gas condensation technique. Using x-ray diffraction (XRD) peak broadening analysis with the Williamson-Hall (W-H) Uniform Deformation Model (UDM) the crystallite size of the NPs and the strain in NPs were found to be 80±38 nm and 3.07×10-3±0.9×10-3 respectively. In comparison, using the Debye-Scherrer's (DS) formula, we have inferred that the crystallite size of the NPs was 23±6 nm and the average strain was 4.3×10-3±0.4×10-3. The scanning electron microscopy images show that the NPs are spherical and have an average diameter of ∼300 nm. The crystallite size is smaller than the size of the NPs revealing their polycrystalline behavior. In addition, the NPs strain, stress and energy density were also calculated using W-H analysis combined with the Uniform Deformation Stress Model (UDSM) and the Uniform Deformation Energy Density Model (UDEDM). Suggested by the spherical geometry and polycrystalline nature of the AlN NPs, the strain computed from UDM, UDSM and UDEDM were in agreement confirming an isotropic mechanical nature of the particle. Luminescence measurements revealed the temperature dependence of the optical emission of the Er3+ ions, confirming the use of AlN:Er NPs for nano-scale temperature sensing.

  14. Successful field evaluation of the efficiency of a gas gravity drainage process by applying recent developments in Sponge coring technique in a major oil field

    SciTech Connect

    Durandeau, M.; El-Emam, M.; Anis, A.H.; Fanti, G.

    1995-11-01

    This paper describes the application and integration of new technologies and recent developments in Sponge coring and presents the methodology used to carry out successfully the various phases of well designed Sponge coring project, including the coring phase, the on-site measurements and the full evaluation of the Sponge core samples. A field case is presented where a Sponge coring project was accomplished to obtain accurate fluids distribution and evaluate the gas gravity drainage efficiency in one of the Arab D sub-reservoirs of a major oil field offshore Abu Dhabi. A Sponge coring technology team was created to optimize the methodology used during Sponge coring an minimize the uncertainties which persisted on some of the previous operations. The effectiveness of the technique is discussed, with comparison to open hole logs and SCAL data. Realistic petrophysical parameters were obtained from non-invaded, native-state core samples. The effective oil saturation obtained from the Sponge core analysis results showed that the gravity segregation mechanism has been very active and efficient to recover the oil in the reservoir.

  15. Simple Techniques For Assessing Impacts Of Oil And Gas Operations On Federal Lands - A Field Evaluation At Big South Fork National River And Recreation Area, Scott County, Tennessee

    USGS Publications Warehouse

    Otton, James K.; Zielinski, Robert A.

    2000-01-01

    Simple, cost-effective techniques are needed for land managers to assess the environmental impacts of oil and gas production activities on public lands so that sites may be prioritized for further, more formal assessment or remediation. These techniques should allow the field investigator to extend the assessment beyond the surface disturbances documented by simple observation and mapping using field-portable instruments and expendable materials that provide real-time data. The principal contaminants of current concern are hydrocarbons, produced water, and naturally occurring radioactive materials (NORM). Field investigators can examine sites for the impacts of hydrocarbon releases using a photoionization detector (PID) and a soil auger. Volatile organic carbon (VOC) in soil gases in an open auger hole or in the head space of a bagged and gently warmed auger soil sample can be measured by the PID. This allows detection of hydrocarbon movement in the shallow subsurface away from areas of obvious oil-stained soils or oil in pits at a production site. Similarly, a field conductivity meter and chloride titration strips can be used to measure salts in water and soil samples at distances well beyond areas of surface salt scarring. Use of a soil auger allows detection of saline subsoils in areas where salts may be flushed from the surface soil layers. Finally, a microRmeter detects the presence of naturally occurring radioactive materials (NORM) in equipment and soils. NORM often goes undetected at many sites although regulations limiting NORM in equipment and soils are being promulgated in several States and are being considered by the USEPA. With each technique, background sampling should be done for comparison with impacted areas. The authors examined sites in the Big South Fork National River and Recreation Area in November of 1999. A pit at one site at the edge of the flood plain of a small stream had received crude oil releases from a nearby tank. Auger holes down

  16. Sensation and gas dynamics in functional gastrointestinal disorders.

    PubMed

    Malagelada, J-R

    2002-07-01

    Our current knowledge of motor and sensory functions in the human gut is critically reviewed, showing how the two may interact to produce symptoms in patients with functional gastrointestinal disorders. A local stimulus is necessary to activate the pathogenetic symptom generation process, and in many patients abnormal pooling of gas at various or extensive sites in the bowel and focal gut distension may provide the local stimulus, compounded by spatial summation phenomena and conscious visceral hypersensitivity. The interplay of these mechanisms results in the clinical expression of symptoms.

  17. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    PubMed

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents.

  18. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    PubMed

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents. PMID:27185056

  19. Optimizing C{sup 4+} and C{sup 5+} beams of the Kei2 electron cyclotron resonance ion source using a special gas-mixing technique

    SciTech Connect

    Drentje, A.G.; Muramatsu, M.; Kitagawa, A.

    2006-03-15

    With the prototype electron cyclotron resonance ion source for the next carbon therapy facility in Japan a series of measurements has been performed in order (a) to find the best condition for producing high beam currents of C{sup 4+} ions, and (b) to study the effect of 'special' gas mixing by using a chemical compound as a feed gas. The effect would then appear as an increase in high charge state production in this case of C{sup 5+} ions. In 'regular' gas-mixing experiments it is well known that an isotopic phenomenon occurs: a heavier isotope of the mixing gas is increasing the production of high charge states of the beam gas ions. A similar isotopic effect has been found in the present experiment: with deuterated methane (CD{sub 4} gas) the C{sup 5+} beam currents are about 10% higher than with regular methane (CH{sub 4} gas). The 'mixing-gas' ratio D (or H) to C can be decreased by choosing, e.g., butane gas; in this case the isotopic effect for C{sup 5+} production is even stronger (>15%). For production of C{sup 4+} ions the isotopic effect appears to be absent. Clearly this is related to the much easier production. It turns out that the relative amount of carbon is much more important: butane gives about 10% higher C{sup 4+}-ion currents than methane.

  20. The antinociceptive effects of intravenous tianeptine in colorectal distension-induced visceral pain in rats: the role of 5-HT₃ receptors.

    PubMed

    Bilge, S Sırrı; Bozkurt, Ayhan; Ilkaya, Fatih; Ciftcioğlu, Engin; Kesim, Yüksel; Uzbay, Tayfun I

    2012-04-15

    Tianeptine is an unusual tricyclic antidepressant drug. In this study, we aimed to investigate the antinociceptive effect of tianeptine on visceral pain in rats and to determine whether possible antinociceptive effect of tianeptine is mediated by serotonergic (5-HT(2,3)) and noradrenergic (α(1,2)) receptor subtypes. Male Sprague Dawley rats (250-300 g) were supplied with a venous catheter, for drug administrations, and enameled nichrome electrodes, for electromyography, at external oblique musculature. Colorectal distension (CRD) was employed as the noxious visceral stimulus and the visceromotor response (VMR) to CRD was quantified electromyographically before and 5, 15, 30, 60, 90 and 120 min after tianeptine administration. Antagonists were administered 10 min before tianeptine for their ability to change tianeptine antinociception. Intravenous administration of tianeptine (2.5-20 mg/kg) produced a dose-dependent reduction in VMR. Administration of 5-HT(3) receptor antagonist ondansetron (0.5, 1 and 2 mg/kg), but not 5-HT(2) receptor antagonist ketanserine (0.5, 1 and 2 mg/kg), reduced the antinociceptive effect of tianeptine (10mg/kg). In addition, administration of α(1)-adrenoceptor antagonist prazosin (1 mg/kg) or α(2)-adrenoceptor antagonist yohimbine (1 mg/kg) did not cause any significant effect on the tianeptine-induced antinociception. Our data indicate that intravenous tianeptine exerts a pronounced antinociception against CRD-induced visceral pain in rats, and suggests that the antinociceptive effect of tianeptine appears to be mediated in part by 5-HT(3) receptors, but does not involve 5-HT(2) receptors or α-adrenoceptors.

  1. The effect of distension pressure on endothelial injury and vasodilatation response in saphenous vein grafts: conversion of a bypass graft to a dead pipe

    PubMed Central

    Gur, Ozcan; Yuksel, Volkan; Tastekin, Ebru; Huseyin, Serhat; Gur, Demet Ozkaramanli; Canbaz, Suat

    2014-01-01

    Introduction Endothelial damage caused by high pressure applied for spasm relaxation during graft preparation is one of the most plausible theories explaining early graft failure. Aim of the study We aimed to demonstrate the extent of endothelial damage in saphenous vein grafts distended to different pressure levels by using immunohistochemical methods and in vitro tissue baths. Material and methods Saphenous vein grafts (SVGs) of 25 patients who underwent isolated elective CABG surgery were used in this study. By using a specific mechanism, SVGs were distended to five different pressure levels for two minutes: 0 mmHg, 50 mmHg, 100 mmHg, 200 mmHg, 300 mmHg. In vitro tissue baths and immunohistochemical examinations were performed. Results None of the grafts distended to 300 mmHg pressure were functional in the tissue bath system. The relaxation response to carbachol of SVGs distended to 0, 50, 100 and 200 mmHg was 97.87 ± 4.47%, 98.52 ± 3.95%, 93.78 ± 3.64%, and 30.87 ± 4.11%, respectively. There were no statistically significant differences in terms of relaxation responses between samples distended to 0, 50, and 100 mmHg (p = 0.490). The relaxation response of samples distended to 200 mmHg was significantly decreased (p = 0.021). The endothelia of samples distended to 0 mmHg were almost intact in CD31 staining. Endothelial cell loss occurred at all tested distension pressures at different degrees. Conclusion In vitro and immunohistochemical studies revealed that distending an SVG used for coronary artery bypass grafting with pressures of 100 mmHg or less results in less endothelial damage and increases graft patency. PMID:26336407

  2. Is serotonin in enteric nerves required for distension-evoked peristalsis and propulsion of content in guinea-pig distal colon?

    PubMed

    Sia, T C; Flack, N; Robinson, L; Kyloh, M; Nicholas, S J; Brookes, S J; Wattchow, D A; Dinning, P; Oliver, J; Spencer, N J

    2013-06-14

    Recent studies have shown genetic deletion of the gene that synthesizes 5-HT in enteric neurons (tryptophan hydroxylase-2, Tph-2) leads to a reduction in intestinal transit. However, deletion of the Tph-2 gene also leads to major developmental changes in enteric ganglia, which could also explain changes in intestinal transit. We sought to investigate this further by acutely depleting serotonin from enteric neurons over a 24-h period, without the confounding influences induced by genetic manipulation. Guinea-pigs were injected with reserpine 24h prior to euthanasia. Video-imaging and spatio-temporal mapping was used to record peristalsis evoked by natural fecal pellets, or slow infusion of intraluminal fluid. Immunohistochemical staining for 5-HT was used to detect the presence of serotonin in the myenteric plexus. It was found that endogenous 5-HT was always detected in myenteric ganglia of control animals, but never in guinea-pigs treated with reserpine. Interestingly, peristalsis was still reliably evoked by either intraluminal fluid, or fecal pellets in reserpine-treated animals that also had their entire mucosa and submucosal plexus removed. In these 5-HT depleted animals, there was no change in the frequency of peristalsis or force generated during peristalsis. In control animals, or reserpine treated animals, high concentrations (up to 10 μM) of ondansetron and SDZ-205-557, or granisetron and SDZ-205-557 had no effect on peristalsis. In summary, acute depletion of serotonin from enteric nerves does not prevent distension-evoked peristalsis, nor propulsion of luminal content. Also, we found no evidence that 5-HT3 and 5-HT4 receptor activation is required for peristalsis, or propulsion of contents to occur. Taken together, we suggest that the intrinsic mechanisms that generate peristalsis and entrain propagation along the isolated guinea-pig distal colon are independent of 5-HT in enteric neurons or the mucosa, and do not require the activation of 5-HT3 or 5

  3. The antinociceptive effects of intravenous tianeptine in colorectal distension-induced visceral pain in rats: the role of 5-HT₃ receptors.

    PubMed

    Bilge, S Sırrı; Bozkurt, Ayhan; Ilkaya, Fatih; Ciftcioğlu, Engin; Kesim, Yüksel; Uzbay, Tayfun I

    2012-04-15

    Tianeptine is an unusual tricyclic antidepressant drug. In this study, we aimed to investigate the antinociceptive effect of tianeptine on visceral pain in rats and to determine whether possible antinociceptive effect of tianeptine is mediated by serotonergic (5-HT(2,3)) and noradrenergic (α(1,2)) receptor subtypes. Male Sprague Dawley rats (250-300 g) were supplied with a venous catheter, for drug administrations, and enameled nichrome electrodes, for electromyography, at external oblique musculature. Colorectal distension (CRD) was employed as the noxious visceral stimulus and the visceromotor response (VMR) to CRD was quantified electromyographically before and 5, 15, 30, 60, 90 and 120 min after tianeptine administration. Antagonists were administered 10 min before tianeptine for their ability to change tianeptine antinociception. Intravenous administration of tianeptine (2.5-20 mg/kg) produced a dose-dependent reduction in VMR. Administration of 5-HT(3) receptor antagonist ondansetron (0.5, 1 and 2 mg/kg), but not 5-HT(2) receptor antagonist ketanserine (0.5, 1 and 2 mg/kg), reduced the antinociceptive effect of tianeptine (10mg/kg). In addition, administration of α(1)-adrenoceptor antagonist prazosin (1 mg/kg) or α(2)-adrenoceptor antagonist yohimbine (1 mg/kg) did not cause any significant effect on the tianeptine-induced antinociception. Our data indicate that intravenous tianeptine exerts a pronounced antinociception against CRD-induced visceral pain in rats, and suggests that the antinociceptive effect of tianeptine appears to be mediated in part by 5-HT(3) receptors, but does not involve 5-HT(2) receptors or α-adrenoceptors. PMID:22348811

  4. Respiratory variation in aortic flow peak velocity and inferior vena cava distensibility as indices of fluid responsiveness in anaesthetised and mechanically ventilated children

    PubMed Central

    Achar, Shreepathi Krishna; Sagar, Maddani Shanmukhappa; Shetty, Ranjan; Kini, Gurudas; Samanth, Jyothi; Nayak, Chaitra; Madhu, Vidya; Shetty, Thara

    2016-01-01

    Background and Aims: Dynamic parameters such as the respiratory variation in aortic flow peak velocity (ΔVpeak) and inferior vena cava distensibility index (dIVC) are accurate indices of fluid responsiveness in adults. Little is known about their utility in children. We studied the ability of these indices to predict fluid responsiveness in anaesthetised and mechanically ventilated children. Methods: This prospective study was conducted in 42 children aged between one to 14 years scheduled for elective surgery under general endotracheal anaesthesia. Mechanical ventilation was initiated with a tidal volume of 10 ml/kg. ΔVpeak, dIVC and stroke volume index (SVI) were measured before and after volume expansion (VE) with 10 ml/kg of crystalloid using transthoracic echocardiography. Patients were considered to be responders (R) and non-responders (NR) when SVI increased to either ≥15% or <15% after VE. ΔVpeak and dIVC were analysed between R and NR. Results: The best cut-off value for ΔVpeak as defined by the receiver operator characteristics (ROC) curve analysis was 12.2%, for which sensitivity, specificity, positive predictive value and negative predictive value were 100%, 94%, 96% and 100%, respectively, the area under the curve was 0.975. The best cut-off value for dIVC as defined by the ROC curve analysis was 23.5%, for which sensitivity, specificity, positive predictive value and negative predictive value were 91%, 89%, 91% and 89%, respectively, the area under the curve was 0.95. Conclusion: ΔVpeak and dIVC are reliable indices of fluid responsiveness in children. PMID:27013751

  5. Parallel decrease in arterial distensibility and in endothelium-dependent dilatation in young women with a history of pre-eclampsia.

    PubMed

    Pàez, Olga; Alfie, José; Gorosito, Marta; Puleio, Pablo; de Maria, Marcelo; Prieto, Noemì; Majul, Claudio

    2009-10-01

    Pre-eclampsia not only complicates 5 to 8% of pregnancies but also increases the risk of maternal cardiovascular disease and mortality later in life. We analyzed three different aspects of arterial function (pulse wave velocity, augmentation index, and flow-mediated dilatation), in 55 nonpregnant, normotensive women (18-33 years old) according to their gestational history: 15 nulliparous, 20 with a previous normotensive, and 20 formerly pre-eclamptic pregnancy. Former pre-eclamptic women showed a significantly higher augmentation index and pulse wave velocity (P < 0.001 and P < 0.05, respectively) and lower flow-mediated dilatation (p = 0.01) compared to control groups. In contrast, sublingual nitroglycerine elicited a comparable vasodilatory response in the three groups. The augmentation index correlated significantly with pulse wave velocity and flow-mediated dilatation (R = 0.28 and R = -0.32, respectively, P < 0.05 for both). No significant correlations were observed between augmentation index or flow-mediated dilatation with age, body mass index (BMI), brachial blood pressure, heart rate, or metabolic parameters (plasma cholesterol, glucose, insulin, or insulin resistance). Birth weight maintained a significantly inverse correlation with the augmentation index (R = -0.51, p < 0.002) but not with flow-mediated dilatation. Our findings revealed a parallel decrease in arterial distensibility and endothelium-dependent dilatation in women with a history of pre-eclampsia compared to nulliparous women and women with a previous normal pregnancy. A high augmentation index was the most consistent alteration associated with a history of pre-eclampsia. The study supports the current view that the generalized arterial dysfunction associated with pre-eclampsia persists subclinically after delivery.

  6. Is serotonin in enteric nerves required for distension-evoked peristalsis and propulsion of content in guinea-pig distal colon?

    PubMed

    Sia, T C; Flack, N; Robinson, L; Kyloh, M; Nicholas, S J; Brookes, S J; Wattchow, D A; Dinning, P; Oliver, J; Spencer, N J

    2013-06-14

    Recent studies have shown genetic deletion of the gene that synthesizes 5-HT in enteric neurons (tryptophan hydroxylase-2, Tph-2) leads to a reduction in intestinal transit. However, deletion of the Tph-2 gene also leads to major developmental changes in enteric ganglia, which could also explain changes in intestinal transit. We sought to investigate this further by acutely depleting serotonin from enteric neurons over a 24-h period, without the confounding influences induced by genetic manipulation. Guinea-pigs were injected with reserpine 24h prior to euthanasia. Video-imaging and spatio-temporal mapping was used to record peristalsis evoked by natural fecal pellets, or slow infusion of intraluminal fluid. Immunohistochemical staining for 5-HT was used to detect the presence of serotonin in the myenteric plexus. It was found that endogenous 5-HT was always detected in myenteric ganglia of control animals, but never in guinea-pigs treated with reserpine. Interestingly, peristalsis was still reliably evoked by either intraluminal fluid, or fecal pellets in reserpine-treated animals that also had their entire mucosa and submucosal plexus removed. In these 5-HT depleted animals, there was no change in the frequency of peristalsis or force generated during peristalsis. In control animals, or reserpine treated animals, high concentrations (up to 10 μM) of ondansetron and SDZ-205-557, or granisetron and SDZ-205-557 had no effect on peristalsis. In summary, acute depletion of serotonin from enteric nerves does not prevent distension-evoked peristalsis, nor propulsion of luminal content. Also, we found no evidence that 5-HT3 and 5-HT4 receptor activation is required for peristalsis, or propulsion of contents to occur. Taken together, we suggest that the intrinsic mechanisms that generate peristalsis and entrain propagation along the isolated guinea-pig distal colon are independent of 5-HT in enteric neurons or the mucosa, and do not require the activation of 5-HT3 or 5

  7. Hepatic portal venous gas and "the aquarium sign" due to intussusception in kawasaki disease.

    PubMed

    Singh, Upendra N; Kapoor, Aditya; Aggarwal, Amita; Kumar, Sudeep; Poddar, Ujjal

    2012-09-01

    The presence of hepatic portal venous gas (HPVG) may be secondary to bowel necrosis, mechanical distension, or intraabdominal sepsis. We describe an unusual and hitherto unreported presence of HPVG manifesting as gas embolization and the unique "aquarium sign" in a patient of Kawasaki's disease. Continuous passage of bubble-like echoes flowing from the hepatic portal venous system into the inferior vena cava and right-sided chambers of heart was noted on echocardiography. The patient was treated with intravenous immune-globulins and made an uneventful recovery.

  8. Simple Techniques For Assessing Impacts Of Oil And Gas Operations On Public Lands: A Field Evaluation Of A Photoionization Detector (PID) At A Condensate Release Site, Padre Island National Seashore, Texas

    USGS Publications Warehouse

    Otton, James K.; Zielinski, Robert A.

    2001-01-01

    Simple, cost-effective techniques are needed for land managers to assess the environmental impacts of oil and gas production activities on public lands, so that sites may be prioritized for remediation or for further, more formal assessment. Field-portable instruments provide real-time data and allow the field investigator to extend an assessment beyond simply locating and mapping obvious disturbances. Field investigators can examine sites for the presence of hydrocarbons in the subsurface using a soil auger and a photoionization detector (PID). The PID measures volatile organic compounds (VOC) in soil gases. This allows detection of hydrocarbons in the shallow subsurface near areas of obvious oil-stained soils, oil in pits, or dead vegetation. Remnants of a condensate release occur in sandy soils at a production site on the Padre Island National Seashore in south Texas. Dead vegetation had been observed by National Park Service personnel in the release area several years prior to our visit. The site is located several miles south of the Malaquite Beach Campground. In early 2001, we sampled soil gases for VOCs in the area believed to have received the condensate. Our purpose in this investigation was: 1) to establish what sampling techniques might be effective in sandy soils with a shallow water and contrast them with techniques used in an earlier study; and 2) delineate the probable area of condensate release. Our field results show that sealing the auger hole with a clear, rigid plastic tube capped at the top end and sampling the soil gas through a small hole in the cap increases the soil VOC gas signature, compared to sampling soil gases in the bottom of an open hole. This sealed-tube sampling method increases the contrast between the VOC levels within a contaminated area and adjacent background areas. The tube allows the PID air pump to draw soil gas from the volume of soil surrounding the open hole below the tube in a zone less influenced by atmospheric air

  9. Impact of the Application Technique on Nitrogen Gas Emissions and Nitrogen Budgets in Case of Energy Maize Fertilized with Biogas Residues

    NASA Astrophysics Data System (ADS)

    Andres, Monique; Fränzke, Manuel; Schuster, Carola; Kreuter, Thomas; Augustin, Jürgen

    2014-05-01

    Despite an increasing cultivation of energy maize fertilized with ammonia-rich biogas residues (BR), little is known about the impact of the application technique on gaseous nitrogen (N) losses as well as N budgets, indicative of N use efficiency. To contribute to closing this knowledge gap we conducted a field experiment supplemented by a laboratory incubation study. The field experiment was carried out in Dedelow, located in the Northeastern German Lowlands and characterized by well-drained loamy sand (haplic luvisol). Two treatments with different application technique for BR fertilization - i) trail hoses and ii) injection - were compared to an unfertilized control (0% N). Seventy percent of the applied N-BR was assumed to be plant-available. In 2013, biweekly nitrous oxide (N2O) measurements were conducted during the time period between BR application and maize harvest (18.04.-11.09.2013; 147 days) using non-flow-through non-steady-state chamber measurements. To quantify soil Nmin status, soil samples were taken from 0-30 cm soil depth in the spring (before fertilization) and autumn (after maize harvest). Immediately after BR application, ammonia (NH3) volatilization was measured intensively using the open dynamic chamber Dräger-Tube method. Export of N due to harvest was determined via plant N content (Nharvest). Based on the measured N gas fluxes, N soil and plant parameters, soil N budgets were calculated using a simple difference approach. Values of N output (Nharvest, NN2O_cum and NNH3_cum) are subtracted from N input values (Nfertilizer and Nmin_autumnminus Nmin_spring). In order to correctly interpret N budgets, other N fluxes must be integrated into the budget calculation. Apart from soil-based mobilization and immobilization turnover processes and nitrate leaching, this applies specifically to N2 losses due to denitrification. Therefore, we measured the N2 emissions from laboratory-incubated undisturbed soil cores (250 cm3) by means of the helium

  10. Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro- or nanochannel: heat flux predictions using combined molecular dynamics and Monte Carlo techniques.

    PubMed

    Nedea, S V; van Steenhoven, A A; Markvoort, A J; Spijker, P; Giordano, D

    2014-05-01

    The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and reflected molecules in molecular dynamics and used as effective coefficients in Maxwell-like boundary conditions in Monte Carlo simulations. Hydrophobic and hydrophilic wall interactions are studied, and the effect of the gas-surface interaction potential on the heat flux and other characteristic parameters like density and temperature is shown. The heat flux dependence on the accommodation coefficient is shown for different fluid-wall mass ratios. We find that the accommodation coefficient is increasing considerably when the mass ratio is decreased. An effective map of the heat flux depending on the accommodation coefficient is given and we show that MC heat flux predictions using Maxwell boundary conditions based on the accommodation coefficient give good results when compared to pure molecular dynamics heat predictions. The accommodation coefficients computed for a dilute gas for different gas-wall interaction parameters and mass ratios are transferred to compute the heat flux predictions for a dense gas. Comparison of the heat fluxes derived using explicit MD, MC with Maxwell-like boundary conditions based on the accommodation coefficients, and pure Maxwell boundary conditions are discussed. A map of the heat flux dependence on the accommodation coefficients for a dense gas, and the effective accommodation coefficients for different gas-wall interactions are given. In the end, this approach is applied to study the gas-surface interactions of argon and xenon molecules on a platinum surface. The derived accommodation coefficients are compared with values of experimental results. PMID:25353885

  11. Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro- or nanochannel: heat flux predictions using combined molecular dynamics and Monte Carlo techniques.

    PubMed

    Nedea, S V; van Steenhoven, A A; Markvoort, A J; Spijker, P; Giordano, D

    2014-05-01

    The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and reflected molecules in molecular dynamics and used as effective coefficients in Maxwell-like boundary conditions in Monte Carlo simulations. Hydrophobic and hydrophilic wall interactions are studied, and the effect of the gas-surface interaction potential on the heat flux and other characteristic parameters like density and temperature is shown. The heat flux dependence on the accommodation coefficient is shown for different fluid-wall mass ratios. We find that the accommodation coefficient is increasing considerably when the mass ratio is decreased. An effective map of the heat flux depending on the accommodation coefficient is given and we show that MC heat flux predictions using Maxwell boundary conditions based on the accommodation coefficient give good results when compared to pure molecular dynamics heat predictions. The accommodation coefficients computed for a dilute gas for different gas-wall interaction parameters and mass ratios are transferred to compute the heat flux predictions for a dense gas. Comparison of the heat fluxes derived using explicit MD, MC with Maxwell-like boundary conditions based on the accommodation coefficients, and pure Maxwell boundary conditions are discussed. A map of the heat flux dependence on the accommodation coefficients for a dense gas, and the effective accommodation coefficients for different gas-wall interactions are given. In the end, this approach is applied to study the gas-surface interactions of argon and xenon molecules on a platinum surface. The derived accommodation coefficients are compared with values of experimental results.

  12. Regional alveolar pressure during periodic flow. Dual manifestations of gas inertia.

    PubMed Central

    Allen, J L; Frantz, I D; Fredberg, J J

    1985-01-01

    We measured pressure excursions at the airway opening and at the alveoli (PA) as well as measured the regional distribution of PA during forced oscillations of six excised dog lungs while frequency (f[2-32 Hz]), tidal volume (VT [5-80 ml]), and mean transpulmonary pressure (PL [25, 10, and 6 cm H2O]) were varied. PA's were measured in four alveolar capsules glued to the pleura of different lobes. The apex-to-base ratio of PA's was used as an index of the distribution of dynamic lung distension. At low f, there was slight preferential distension of the lung base which was independent of VT, but at higher f, preferential distension of the lung apex was found when VT's were small, whereas preferential distension of the lung base was found when VT's approached or exceeded dead space. These VT-related changes in distribution at high frequencies seem to depend upon the branching geometry of the central airways and the relative importance of convective momentum flux vs. unsteady inertia of gas residing therein, which, in this study, we showed to be proportional to the ratio VT/VD*, where VD* is an index of dead space. Furthermore, they imply substantial alteration in the distribution of ventilation during high frequency ventilation as f, VT, and PL vary. The data also indicate that alveolar and airway opening pressure costs per unit flow delivered at the airway opening exhibit weakly nonlinear behavior and that resonant amplification of PA's, which has been described previously for the case of very small VT's, persists but is damped as VT's approach dead space values. PMID:4031066

  13. Data reduction analysis and application technique development for atmospheric trace gas constituents derived from remote sensors on satellite or airborne platforms

    NASA Technical Reports Server (NTRS)

    Casas, J. C.; Campbell, S. A.

    1981-01-01

    The applicability of the gas filter correlation radiometer (GFCR) to the measurement of tropospheric carbon monoxide gas was investigated. An assessment of the GFRC measurement system to a regional measurement program was conducted through extensive aircraft flight-testing of several versions of the GFRC. Investigative work in the following areas is described: flight test planning and coordination, acquisition of verifying CO measurements, determination and acquisition of supporting meteorological data requirements, and development of supporting computational software.

  14. Determination of C1-C5 alkyl nitrates in rain, snow, white frost, lake, and tap water by a combined codistillation head-space gas chromatography technique. Determination of Henry's law constants by head-space GC.

    PubMed

    Hauff, K; Fischer, R G; Ballschmiter, K

    1998-12-01

    Alkyl nitrates with a chain length up to five carbon atoms have been determined in snow, white frost, and surface water. The samples were taken in the vicinity of Ulm, Germany, a region in central Europe. The determination of C1-C5-alkyl nitrates in water samples was achieved with a new water codistillation enrichment technique directly coupled with on-column head-space gas chromatography. The concentrations of the short chain alkyl nitrates in the different forms of wet deposition range from 89 ng L-1 for 1-propyl nitrate down to 35 ng L-1 for 1-pentyl nitrate. C1-C5-alkyl nitrates in wet depositions were also directly determined by static head-space gas chromatography. Gas-water partition coefficients KGW (Henry's law constant H) were determined by head-space gas chromatography and secondly by calculating the Henry's law constant by the ratio of vapor pressure to water solubility. The gas-water partition constants (dimensionless) or Henry's law constants range from KGW = 0.038 (H = 93 Pa m3 mol-1) for 1-propyl nitrate up to KGW = 0.122 (H = 302 Pa m3 mol-1) for 2-pentyl nitrate.

  15. Effects of Bladder Distension on Organs at Risk in 3D Image-Based Planning of Intracavitary Brachytherapy for Cervical Cancer

    SciTech Connect

    Kim, Robert Y.; Shen Sui; Lin Huiyi; Spencer, Sharon A.; De Los Santos, Jennifer

    2010-02-01

    Purpose: To investigate the effects of bladder distension on organs at risk (OARs) in the image-based planning of intracavitary brachytherapy for cervical cancer. Methods and Materials: Thirteen patients with cancer of the cervix were treated with high-dose radiation brachytherapy (800 cGy/fraction for 3 fractions). For the three-dimensional (3D) analysis, pelvic CT scans were obtained from patients with indwelling catheters in place (defined as empty bladder) and from patients who received 180-cc injections of sterile water in their bladders (defined as full bladder). To compare the International Commission on Radiation Units and Measurements (ICRU) point doses with 3D-volume doses, the volume dose was defined by using two different criteria, D{sub 2cc} (the minimum dose value in a 2.0-cm{sup 3} volume receiving the highest dose) and D{sub 50%} (the dose received by 50% of the volume of the OAR) for OARs. Results: The bladder D{sub 2cc} was located more cranially in the bladder base and was distributed in multiple spots in 46% of patients. The rectal D{sub 2cc} was located in the area of the ICRU point as a single 'hot spot.' For patients with a full bladder, the mean bladder D{sub 2cc} increased from 634 to 799 cGy (28.8%, p = 0.002). However, the bowel D{sub 2cc} decreased from 475 to 261 cGy (45.0%, p < 0.001). There were no substantial differences in rectal and sigmoid D{sub 2cc} values. However, the mean D{sub 50%} values of both the bladder and the bowel decreased from 108 to 80 cGy (23.7%, p < 0.001) and from 282 to 221 cGy (19.7%, p = 0.004) with a full bladder, respectively. Conclusions: An increase in bladder volume resulted in a significant reduction in bowel D{sub 2cc} values at the expense of an increase in bladder D{sub 2cc} values. Treatment with a distended bladder is preferable to protect the bowel.

  16. A nitro-arginine derivative of trimebutine (NO2-Arg-Trim) attenuates pain induced by colorectal distension in conscious rats.

    PubMed

    Distrutti, Eleonora; Mencarelli, Andrea; Renga, Barbara; Caliendo, Giuseppe; Santagada, Vincenzo; Severino, Beatrice; Fiorucci, Stefano

    2009-05-01

    Irritable bowel syndrome (IBS) is characterized by dysfunction of the afferent pathways that may lead to visceral hypersensitivity. Trimebutine is a weak opioid receptor agonist used in the treatment of IBS. We report on the effects of a novel derivative in which trimebutine has been salified with nitro-arginine(NO2-Arg-Trim), in modulating nociception to colorectal distension (CRD) in intact and post-colitis rats,an animal model that mimics some features of IBS. Colorectal sensitivity and pain were assessed by measuring the abdominal withdrawal score (AWR) during CRD. Healthy rats were treated with vehicle,trimebutine (10 mg/kg i.p.) or NO2-Arg-Trim (4, 8 and 16 mg/kg i.p.). Post-colitis, allodynic rats were investigated 4 weeks after colitis induction. Treating healthy rats with NO2-Arg-Trim resulted in a dose-dependent attenuation of CRD-induced nociception and in an inhibition of CRD-induced overexpression of spinal cFOS mRNA. NO2-Arg-Trim-induced antinociception was reversed by the opioid receptor antagonist naloxone and by the NO synthase-cGMP pathway inhibitor methylene blue, while L-NAME had no effect.The antinociceptive effect of NO2-Arg-Trim was maintained in a rodent model of post-inflammatory allodynia. In this setting,NO2-Arg-Trim but not trimebutine, significantly down-regulated the spinal cFOS mRNA expression and increased blood concentrations of NO2 +NO3. Moreover, the expression of several genes involved in inflammation and pain, as IL-1beta, TNFalpha, COX2 and iNOS, was up-regulated in colonic tissue from post-colitis rats and NO2-Arg-Trim, but not trimebutine, effectively reversed this effect. In summary, these data suggest that NO2-Arg-Trim inhibits nociception induced by CRD in both healthy and post-colitis, allodynic rats. The NO2-arginine moiety interacts with the opioid agonist trimebutine to potentiate its analgesic activity. This study provides evidence that NO2-arginine derivative of trimebutine might have beneficial effect in the

  17. Comparison of trans-perineal ultrasound-guided pressure augmented saline colostomy distension study and conventional contrast radiographic colostography in children with anorectal malformation

    PubMed Central

    Ekwunife, Okechukwu Hyginus; Umeh, Eric Okechukwu; Ugwu, Jideofor Okechukwu; Ebubedike, Uzoamaka Rufina; Okoli, Chinedu Christian; Modekwe, Victor Ifeanyichukwu; Elendu, Kelechi Collins

    2016-01-01

    Background: In children with high and intermediate anorectal malformation, distal colostography is an important investigation done to determine the relationship between the position of the rectal pouch and the probable site of the neo-anus as well as the presence or absence of a fistula. Conventionally, this is done using contrast with fluoroscopy or still X-ray imaging. This, however, has the challenges of irradiation, availability and affordability, especially in developing countries. This study compared the accuracy of trans-perineal ultrasound-guided pressure augmented saline colostomy distension study (SCDS) with conventional contrast distal colostography (CCDC) in the determination of the precise location of the distal rectal pouch and in detecting the presence and site of fistulous communication between the rectum and the urogenital tract was studied. Materials and Methods: Trans-perineal ultrasound-guided pressure augmented SCDS, CCDC and intra-operative measurements were done sequentially for qualified infants with anorectal malformation and colostomy. Pouch skin distance and presence or absence of recto urinary or genital fistula was measured prospectively in each case. Statistical significance was inferred at P-value of <0.01. Results: There were thirteen infants, 9 males and 4 females. The age at onset of investigation ranged from 2 to 12 months with a median value of 9 months. Using paired t-test at a confidence interval of 95%, the P value when SCDS values are compared with CCDC is 0.19; and 0.06 when SCDS was compared with intra-operative measurements. Hence, there is no statistical difference as P > 0.01. On its ability to detect presence or absence of a fistula: SCDS had a sensitivity of 50.0%, specificity of 100.0%, accuracy of 69.2%, negative predictive value of fistulas of 55.6% and a positive predictive value of fistulas of 100.0%. Conclusion: Ultrasound-guided pressure augmented SCDS can safely and reliably be used to assess the distal colonic

  18. A gas-jet transport and catcher technique for on-line production of radioactive ion beams using an electron cyclotron resonance ion-source

    NASA Astrophysics Data System (ADS)

    Naik, V.; Chakrabarti, A.; Bhattacharjee, M.; Karmakar, P.; Bandyopadhyay, A.; Bhattacharjee, S.; Dechoudhury, S.; Mondal, M.; Pandey, H. K.; Lavanyakumar, D.; Mandi, T. K.; Dutta, D. P.; Kundu Roy, T.; Bhowmick, D.; Sanyal, D.; Srivastava, S. C. L.; Ray, A.; Ali, Md. S.

    2013-03-01

    Radioactive ion beams (RIB) have been produced on-line, using a gas-jet recoil transport coupled Electron Cyclotron Resonance (ECR) ion-source at the VECC-RIB facility. Radioactive atoms/molecules carried through the gas-jet were stopped in a catcher placed inside the ECR plasma chamber. A skimmer has been used to remove bulk of the carrier gas at the ECR entrance. The diffusion of atoms/molecules through the catcher has been verified off-line using stable isotopes and on-line through transmission of radioactive reaction products. Beams of 14O (71 s), 42K (12.4 h), 43K (22.2 h), and 41Ar (1.8 h) have been produced by bombarding nitrogen and argon gas targets with proton and alpha particle beams from the K130 cyclotron at VECC. Typical measured intensity of RIB at the separator focal plane is found to be a few times 103 particles per second (pps). About 3.2 × 103 pps of 1.4 MeV 14O RIB has been measured after acceleration through a radiofrequency quadrupole linac. The details of the gas-jet coupled ECR ion-source and RIB production experiments are presented along with the plans for the future.

  19. Analytical techniques for selection of repair-or-replace options for cast-iron gas piping systems--Phase I. Topical report, March 1985-June 1986

    SciTech Connect

    Kulkarni, R.B.; Golabi, K.; Chuang, J.

    1986-01-01

    A Cast Iron Maintenance Optimization System (CIMOS) was developed to identify failure-prone segments of cast-iron gas-piping systems and to determine the most-economical timing for replacing specific segments of such piping systems. The CIMOS provides a practical analytical tool that can be used by the gas industry to: (a) estimate probabilities of breaks and leaks on different cast-iron piping-system segments; (b) evaluate whether it is more economical (in terms of total current and future expected costs) to replace any given pipeline segment in the current year or to continue maintaining it with repairs as needed; (c) find the optimal group of pipeline segments to be replaced, and their priority order, for any designated budget; and (d) select the most cost-effective repair policy for those segments which would not be replaced. The CIMOS was fully developed and tested by one gas utility.

  20. Empirical Methods for Detecting Regional Trends and Other Spatial Expressions in Antrim Shale Gas Productivity, with Implications for Improving Resource Projections Using Local Nonparametric Estimation Techniques

    USGS Publications Warehouse

    Coburn, T.C.; Freeman, P.A.; Attanasi, E.D.

    2012-01-01

    The primary objectives of this research were to (1) investigate empirical methods for establishing regional trends in unconventional gas resources as exhibited by historical production data and (2) determine whether or not incorporating additional knowledge of a regional trend in a suite of previously established local nonparametric resource prediction algorithms influences assessment results. Three different trend detection methods were applied to publicly available production data (well EUR aggregated to 80-acre cells) from the Devonian Antrim Shale gas play in the Michigan Basin. This effort led to the identification of a southeast-northwest trend in cell EUR values across the play that, in a very general sense, conforms to the primary fracture and structural orientations of the province. However, including this trend in the resource prediction algorithms did not lead to improved results. Further analysis indicated the existence of clustering among cell EUR values that likely dampens the contribution of the regional trend. The reason for the clustering, a somewhat unexpected result, is not completely understood, although the geological literature provides some possible explanations. With appropriate data, a better understanding of this clustering phenomenon may lead to important information about the factors and their interactions that control Antrim Shale gas production, which may, in turn, help establish a more general protocol for better estimating resources in this and other shale gas plays. ?? 2011 International Association for Mathematical Geology (outside the USA).

  1. An improved algorithm of image processing technique for film thickness measurement in a horizontal stratified gas-liquid two-phase flow

    NASA Astrophysics Data System (ADS)

    Kuntoro, Hadiyan Yusuf; Hudaya, Akhmad Zidni; Dinaryanto, Okto; Majid, Akmal Irfan; Deendarlianto

    2016-06-01

    Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methods and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (hL) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works.

  2. Evalution of seismic amplitude versus offset techniques for the direct detection of gas reservoirs. Phase 2. Increasing the use of amplitude versus offset techniques in the continental United States. Annual report, December 1993-December 1994

    SciTech Connect

    Peddy, C.P.

    1995-06-01

    This annual report describes a study evaluating the amplitude versus offset technique in the Gulf Coast (Phase I) and Mid-Continent (Phase II) regions of the United States. This report covers the technology transfer of the results of Phase I.

  3. Temperature-programmed technique accompanied with high-throughput methodology for rapidly searching the optimal operating temperature of MOX gas sensors.

    PubMed

    Zhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, Dawen

    2014-09-01

    A combinatorial high-throughput temperature-programmed method to obtain the optimal operating temperature (OOT) of gas sensor materials is demonstrated here for the first time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temperature-dependent conductivity curves were obtained by scanning this gas sensor library from 300 to 700 K in different atmospheres (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temperature-programmed method and a conventional method showed good agreement in measured OOT. PMID:25090138

  4. Water quality studied in areas of unconventional oil and gas development, including areas where hydraulic fracturing techniques are used, in the United States

    USGS Publications Warehouse

    Susong, David D.; Gallegos, Tanya J.; Oelsner, Gretchen P.

    2012-01-01

    The U.S. Geological Survey (USGS) John Wesley Powell Center for Analysis and Synthesis is hosting an interdisciplinary working group of USGS scientists to conduct a temporal and spatial analysis of surface-water and groundwater quality in areas of unconventional oil and gas development. The analysis uses existing national and regional datasets to describe water quality, evaluate water-quality changes over time where there are sufficient data, and evaluate spatial and temporal data gaps.

  5. Measurement of N2, N2O, NO, and CO2 emissions from soil with the gas-flow-soil-core technique.

    PubMed

    Wang, Rui; Willibald, Georg; Feng, Qi; Zheng, Xunhua; Liao, Tingting; Brüggemann, Nicolas; Butterbach-Bahl, Klaus

    2011-07-15

    Here we describe a newly designed system with three stand-alone working incubation vessels for simultaneous measurements of N(2), N(2)O, NO, and CO(2) emissions from soil. Due to the use of a new micro thermal conductivity detector and the redesign of vessels and gas sampling a so-far unmatched sensitivity (0.23 μg N(2)-N h(-1) kg(-1) ds or 8.1 μg N(2)-N m(-2) h(-1)) for detecting N(2) gas emissions and repeatability of experiments could be achieved. We further tested different incubation methods to improve the quantification of N(2) emission via denitrification following the initialization of soil anaerobiosis. The best results with regard to the establishment of a full N balance (i.e., the changes in mineral N content being offset by simultaneous emission of N gases) were obtained when the anaerobic soil incubation at 25 °C was preceded by soil gas exchange under aerobic conditions at a lower incubation temperature. The ratios of N and C gas emission changed very dynamically following the initialization of anaerobiosis. For soil NO(3)(-) contents of 50 mg N kg(-1) dry soil (ds) and dissolved organic carbon (DOC) concentrations of approximately 300 mg C kg(-1) ds, the cumulative emissions of N(2), N(2)O, and NO were 24.3 ± 0.1, 12.6 ± 0.4, and 10.1 ± 0.3 mg N kg(-1) ds, respectively. Thus, N gas emissions accounted (on average) for 46.2% (N(2)), 24.0% (N(2)O), and 19.2% (NO) of the observed changes in soil NO(3)(-). The maximum N(2) emission reached 1200 μg N h(-1) kg(-1) ds, whereas the peak emissions of N(2)O and NO were lower by a factor of 2-3. The overall N(2):N(2)O and NO:N(2)O molar ratios were 1.6-10.0 and 1.6-2.3, respectively. The measurement system provides a reliable tool for studying denitrification in soil because it offers insights into the dynamics and magnitude of gaseous N emissions due to denitrification under various incubation conditions.

  6. A giant gas-filled abdominal mass in an elderly female: a case report.

    PubMed

    Chong, Hoi Man Deon; Lee, Fung Yee Janet; Lo, Anthony; Li, Chak Man Jimmy

    2011-08-21

    We report an extremely rare case of gas-filled abdominal mass caused by an ovarian teratoma fistulating to the sigmoid colon. The patient was an 85-year-old female, who presented with severe abdominal distension. Urgent computed tomography scan showed a huge abdominal mass with air fluid level and fecal matter inside. Communication between the mass and the sigmoid colon was suspected. She underwent emergency laparotomy. The mass was resected with the involved segment of colon. Pathology confirmed squamous cell carcinoma arising from mature cystic teratoma of the ovary.

  7. Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique.

    PubMed

    Seresinhe, T; Madushika, S A C; Seresinhe, Y; Lal, P K; Orskov, E R

    2012-10-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental

  8. Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique.

    PubMed

    Seresinhe, T; Madushika, S A C; Seresinhe, Y; Lal, P K; Orskov, E R

    2012-10-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental

  9. Effects of Tropical High Tannin Non Legume and Low Tannin Legume Browse Mixtures on Fermentation Parameters and Methanogenesis Using Gas Production Technique

    PubMed Central

    Seresinhe, T.; Madushika, S. A. C.; Seresinhe, Y.; Lal, P. K.; Ørskov, E. R.

    2012-01-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it’s highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental

  10. Nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA) of liposomes: applicability of the technique for nano vesicle batch control

    PubMed Central

    Weiss, Victor U.; Urey, Carlos; Gondikas, Andreas; Golesne, Monika; Friedbacher, Gernot; von der Kammer, Frank; Hofmann, Thilo; Andersson, Roland; Marko-Varga, György; Marchetti-Deschmann, Martina

    2016-01-01

    Liposomes are biodegradable nanoparticle vesicles consisting of a lipid bilayer encapsulating an aqueous core. Entrapped cargo material is shielded from the extra-vesicular medium and sustained release of encapsulated material can be achieved. However, application of liposomes as nano-carriers demands their characterization concerning size and size distribution, particle-number concentration, occurrence of vesicle building blocks in solution and determination of the resulting vesicle encapsulation capacity. These questions can be targeted via gas-phase electrophoretic mobility molecular analysis (GEMMA) based on a nano electrospray (nES) charge-reduction source. This instrument separates single-charged nanoparticles in the gas-phase according to size in a high-laminar sheath-flow by means of an orthogonal, tunable electric field. nES GEMMA analysis enables to confirm liposome integrity after passage through the instrument (in combination with atomic force microscopy) as well as to exclude vesicle aggregation. Additionally, nanoparticle diameters at peak apexes and size distribution data are obtained. Differences of hydrodynamic and dry particle diameter values, as well as the effect of number- and mass-based concentration data analysis on obtained liposome diameters are shown. Furthermore, the repeatability of liposome preparation is studied, especially upon incorporation of PEGylated lipids in the bilayer. Finally, the instruments applicability to monitor mechanical stress applied to vesicles is demonstrated. PMID:27549027

  11. Bridging operational shut-downs of the ammonia washer of a plant operating according to the semi-direct technique for the removal of ammonia from coking oven gas

    SciTech Connect

    Diemer, P.

    1985-07-23

    A process and system are disclosed for the bridging of operational standstills of an ammonia washer of a plant operating according to the semi-direct technique for the removal of ammonia from coking oven gas. During the operational standstills of the ammonia washer, the ammonia is washed out from the coking oven gas in a secondary cooler constituting three parts, an upper part (Wash Stage I) provided with stripped water from an ammonia still, a middle part (wash stage II) provided with gas water, and a lower part (wash stage III) provided with circulation water. All of the waters provided for the secondary cooler are collected in its sump, and after a separation of the circulation water necessary for the Wash Stage III, it is split into two partial streams, one serving for the recovery of stripped water for Wash Stage I and which is led into an ammonia still provided only with water vapor and the other partial stream is led into an ammonia still provided with water vapor and alkali. Also disclosed is a system containing a secondary cooler defining three vertically disposed sections of metal mesh beds.

  12. Dense Molecular Gas in the First Galactic Quadrant: A New Distance Estimation Technique and the Molecular Cloud Clump Mass Function, Physical Properties, and Galactic Distribution from the Bolocam Galactic Plane Survey

    NASA Astrophysics Data System (ADS)

    Glenn, Jason; Ellsworth-Bowers, Timothy; Bolocam Galactic Plane Survey

    2015-01-01

    Large submillimeter and millimeter Galactic dust continuum surveys of the Milky Way, such as the Bolocam Galactic Plane Survey (BGPS), Hi-GAL, ATLAS-GAL, and JCMT-JPS cumulatively have discovered 105 cores, clumps, and other structures in Galactic molecular clouds. Robust distance measurements to these structures are needed to enable the large range of quantitative astrophysics that these surveys promise, such as physical properties of clumps, the clump mass function, and the three-dimensional distribution of dense gas and star formation in the Milky Way. We have developed a technique for deriving distances to continuum-identified molecular cloud clumps employing kinematic distances and a suite of distance estimators for breaking kinematic distance ambiguities. Application to the BGPS has yielded 3,700 distance probability density functions (DPDFs) and 1,800 well-constrained distances (typical σdist ≈ 0.5 kpc). These have been used to determine sizes and masses of molecular cloud clumps, derive the clump mass function, and map the three-dimensional distribution of dense gas in the first Galactic quadrant. Among the interesting results are a mass function intermediate between molecular clouds and the stellar initial mass function and inter-arm star formation. Next, we plan to apply the technique to Hi-GAL, which covers the entire Galactic plane and whose submilllimeter maps provide for temperature and bolometric luminosity measurements of cloud structures.

  13. Right Pulmonary Artery Distensibility Index (RPAD Index). A field study of an echocardiographic method to detect early development of pulmonary hypertension and its severity even in the absence of regurgitant jets for Doppler evaluation in heartworm-infected dogs.

    PubMed

    Venco, Luigi; Mihaylova, Liliya; Boon, June A

    2014-11-15

    Despite the term "heartworm disease" Dirofilaria immitis infection in dogs should be considered a pulmonary arterial disease that might only involve the right heart structures in its late stage. Chronic infection by adult heartworms in dogs results in proliferative endoarteritis leading to progressively increasing pulmonary artery pressure due to reduced elasticity. Elasticity allows the pulmonary arteries to stretch in response to each pulse and helps maintain a relatively constant pressure in the arteries despite the pulsating nature of the blood flow. Pulmonary artery distensibility for both acute and chronic pulmonary hypertension has been investigated in humans using MRI and has been correlated with the severity of hypertension and its outcome and treatment response. The aim of the present study was to investigate whether echocardiographic measurement of the percentage change in diameter of the right pulmonary artery in systole and diastole (distensibility) may be of value in assessing the presence and severity of pulmonary hypertension in heartworm-infected dogs. The Right Pulmonary Artery Distensibility Index (RPAD Index) (which is calculated as the difference in diameter of the right pulmonary artery in systole and diastole) was calculated in healthy and naturally infected heartworm-positive dogs. The right pulmonary artery was chosen because it is usually affected earlier and to a greater degree. Data were obtained from healthy heartworm-free dogs without any clinical, radiographic, or echocardiographic signs of pulmonary hypertension; naturally infected heartworm-positive dogs in different stages of the disease in which pulmonary pressure could be measured by Doppler echocardiography (using tricuspid and or pulmonary regurgitation velocity and pressure gradient); and naturally infected heartworm-positive dogs in different stages of the disease (with or without tricuspid and or pulmonary regurgitation) in which the pulmonary pressure was measured

  14. Identification of organic sulfur compounds in coal bitumen obtained by different extraction techniques using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometric detection.

    PubMed

    Machado, Maria Elisabete; Fontanive, Fernando Cappelli; de Oliveira, José Vladimir; Caramão, Elina Bastos; Zini, Cláudia Alcaraz

    2011-11-01

    The determination of organic sulfur compounds (OSC) in coal is of great interest. Technically and operationally these compounds are not easily removed and promote corrosion of equipment. Environmentally, the burning of sulfur compounds leads to the emission of SO(x) gases, which are major contributors to acid rain. Health-wise, it is well known that these compounds have mutagenic and carcinogenic properties. Bitumen can be extracted from coal by different techniques, and use of gas chromatography coupled to mass spectrometric detection enables identification of compounds present in coal extracts. The OSC from three different bitumens were tentatively identified by use of three different extraction techniques: accelerated solvent extraction (ASE), ultrasonic extraction (UE), and supercritical-fluid extraction (SFE). Results obtained from one-dimensional gas chromatography (1D GC) coupled to quadrupole mass spectrometric detection (GC-qMS) and from two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC × GC-TOFMS) were compared. By use of 2D GC, a greater number of OSC were found in ASE bitumen than in SFE and UE bitumens. No OSC were identified with 1D GC-qMS, although some benzothiophenes and dibenzothiophenes were detected by use of EIM and SIM modes. GC × GC-TOFMS applied to investigation of OSC in bitumens resulted in analytical improvement, as more OSC classes and compounds were identified (thiols, sulfides, thiophenes, naphthothiophenes, benzothiophenes, and benzonaphthothiophenes). The roof-tile effect was observed for OSC and PAH in all bitumens. Several co-elutions among analytes and with matrix interferents were solved by use of GC × GC.

  15. Inter-laboratory calibration of natural gas round robins for δ2H and δ13C using off-line and on-line techniques

    USGS Publications Warehouse

    Dai, Jinxing; Xia, Xinyu; Li, Zhisheng; Coleman, Dennis D.; Dias, Robert F.; Gao, Ling; Li, Jian; Deev, Andrei; Li, Jin; Dessort, Daniel; Duclerc, Dominique; Li, Liwu; Liu, Jinzhong; Schloemer, Stefan; Zhang, Wenlong; Ni, Yunyan; Hu, Guoyi; Wang, Xiaobo; Tang, Yongchun

    2012-01-01

    Compound-specific carbon and hydrogen isotopic compositions of three natural gas round robins were calibrated by ten laboratories carrying out more than 800 measurements including both on-line and off-line methods. Two-point calibrations were performed with international measurement standards for hydrogen isotope ratios (VSMOW and SLAP) and carbon isotope ratios (NBS 19 and L-SVEC CO2). The consensus δ13C values and uncertainties were derived from the Maximum Likelihood Estimation (MLE) based on off-line measurements; the consensus δ2H values and uncertainties were derived from MLE of both off-line and on-line measurements, taking the bias of on-line measurements into account. The calibrated consensus values in ‰ relative to VSMOW and VPDB are: NG1 (coal-related gas): Methane: δ2HVSMOW = − 185.1‰ ± 1.2‰, δ13CVPDB = − 34.18‰ ± 0.10‰ Ethane: δ2HVSMOW = − 156.3‰ ± 1.8‰, δ13CVPDB = − 24.66‰ ± 0.11‰ Propane: δ2HVSMOW = − 143.6‰ ± 3.3‰, δ13CVPDB = − 22.21‰ ± 0.11‰ i-Butane: δ13CVPDB = − 21.62‰ ± 0.12‰ n-Butane: δ13CVPDB = − 21.74‰ ± 0.13‰ CO2: δ13CVPDB = − 5.00‰ ± 0.12‰ NG2 (biogas): Methane: δ2HVSMOW = − 237.0‰ ± 1.2‰, δ13CVPDB = − 68.89‰ ± 0.12‰ NG3 (oil-related gas): Methane: δ2HVSMOW = − 167.6‰ ± 1.0‰, δ13CVPDB = − 43.61‰ ± 0.09‰ Ethane: δ2HVSMOW = − 164.1‰ ± 2.4‰, δ13CVPDB = − 40.24‰ ± 0.10‰ Propane: δ2HVSMOW = − 138.4‰ ± 3.0‰, δ13CVPDB = − 33.79‰ ± 0.09‰ All of the assigned values are traceable to the international carbon isotope standard of VPDB and hydrogen isotope standard of VSMOW.

  16. Application of the 15N gas-flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    NASA Astrophysics Data System (ADS)

    Sgouridis, Fotis; Stott, Andrew; Ullah, Sami

    2016-03-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilized agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in-house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps and a copper-based reduction furnace, and allows the analysis of small gas injection volumes (4 µL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Preconcentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N gas-flux method was adapted for application in natural and semi-natural land use types (peatlands, forests, and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. The minimum detectable flux rates were 4 µg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. Total denitrification rates measured by the acetylene inhibition technique in the same land use types correlated (r = 0.58) with the denitrification rates measured under the 15N gas-flux method, but were underestimated by a factor of 4, and this was partially attributed to the incomplete inhibition of N2O reduction to N2, under a relatively high soil moisture content, and/or the catalytic NO decomposition in the presence of acetylene. Even though relatively robust for in situ denitrification measurements, methodological

  17. A new technique for the strengthening of aluminum tungsten inert gas weld metals: using carbon nanotube/aluminum composite as a filler metal.

    PubMed

    Fattahi, M; Nabhani, N; Rashidkhani, E; Fattahi, Y; Akhavan, S; Arabian, N

    2013-01-01

    The effect of multi-walled carbon nanotube (MWCNT) on the mechanical properties of aluminum multipass weld metal prepared by the tungsten inert gas (TIG) welding process was investigated. High energy ball milling was used to disperse MWCNT in the aluminum powder. Carbon nanotube/aluminum composite filler metal was fabricated for the first time by hot extrusion of ball-milled powders. After welding, the tensile strength, microhardness and MWCNT distribution in the weld metal were investigated. The test results showed that the tensile strength and microhardness of weld metal was greatly increased when using the filler metal containing 1.5 wt.% MWCNT. Therefore, according to the results presented in this paper, it can be concluded that the filler metal containing MWCNT can serve as a super filler metal to improve the mechanical properties of TIG welds of Al and its alloys.

  18. A new technique for the strengthening of aluminum tungsten inert gas weld metals: using carbon nanotube/aluminum composite as a filler metal.

    PubMed

    Fattahi, M; Nabhani, N; Rashidkhani, E; Fattahi, Y; Akhavan, S; Arabian, N

    2013-01-01

    The effect of multi-walled carbon nanotube (MWCNT) on the mechanical properties of aluminum multipass weld metal prepared by the tungsten inert gas (TIG) welding process was investigated. High energy ball milling was used to disperse MWCNT in the aluminum powder. Carbon nanotube/aluminum composite filler metal was fabricated for the first time by hot extrusion of ball-milled powders. After welding, the tensile strength, microhardness and MWCNT distribution in the weld metal were investigated. The test results showed that the tensile strength and microhardness of weld metal was greatly increased when using the filler metal containing 1.5 wt.% MWCNT. Therefore, according to the results presented in this paper, it can be concluded that the filler metal containing MWCNT can serve as a super filler metal to improve the mechanical properties of TIG welds of Al and its alloys. PMID:23948441

  19. Measurement of the local aortic stiffness by a non-invasive bioelectrical impedance technique.

    PubMed

    Collette, Mathieu; Lalande, Alain; Willoteaux, Serge; Leftheriotis, Georges; Humeau, Anne

    2011-04-01

    Aortic stiffness measurement is well recognized as an independent predictor of cardiovascular mortality and morbidity. Recently, a simple method has been proposed for the evaluation of the local aortic stiffness (AoStiff) using a non-invasive bioelectrical impedance (BI) technique. This approach relies on a novel interpretation of the arterial stiffness where AoStiff is computed from the measurement of two new BI variables: (1) the local aortic flow resistance (AoRes) exerted by the drag forces onto the flow; (2) the local aortic wall distensibility (AoDist). Herein, we propose to detail and compare these three indices with the reference pulse wave velocity (PWV) measurement and the direct assessment of the aortic drag forces (DF) and distensibility (DS) obtained by the magnetic resonance imaging technique. Our results show a significant correlation between AoStiff and PWV (r = 0.79; P < 0.0001; 120 patients at rest; mean age 44 ± 16 years), and also between AoRes and DF (r = 0.95; P = 0.0011) and between AoDist and DS (r = 0.93; P = 0.0022) on eight patients at rest (mean age 52 ± 19 years). These first results suggest that local aortic stiffness can be explored reliably by the BI technique.

  20. Subsea Target Measurement Technique of High Resolution Multi-Beam Sonar System -A Case Study of Ocean Oil & Gas Production Platform and Pipeline Detection

    NASA Astrophysics Data System (ADS)

    Ding, J.; Tang, Q.; Zhou, X.

    2015-12-01

    Abstract: with fast development of modern science and technology, subsea pipeline detection means have been increasingly improved which have not only improved detection efficiency, but also extremely advanced the detection precision. The article has integrated the performance characteristics of high resolution multi-beam measurement system in recent years, which has introduced the relevant technique and detection achievement of subsea pipeline detecting (especially for exposed pipeline) by detection cases. The final detection result has been verified that high resolution multi-beam measurement system could accurately detect subsea minisize target object, which has provided the technical reference with popularization and application of new characteristics.

  1. Inverse gas chromatography as a technique for the characterization of the performance of Mn/Zr mixed oxides as combustion catalysts.

    PubMed

    Cuervo, Montserrat R; Díaz, Eva; de Rivas, Beatriz; López-Fonseca, Rubén; Ordóñez, Salvador; Gutiérrez-Ortiz, José I

    2009-11-01

    Adsorption of different volatile organic compounds (trichloroethylene, TCE; 1,2-dichloroethane, DCE; n-hexane) over different manganese-zirconia mixed oxides (Mn(x)Zr(1-x)O(2)) - widely used as combustion catalysts - was studied by inverse gas chromatography. Adsorption isotherms (calculated in the Henry region), adsorption enthalpies (DeltaH(ads)), and dispersive (gamma(S)(D)) and specific (I(sp)) components of the surface energy have been determined at infinite dilution for the investigated compounds. Both the adsorption enthalpy and the specificity of the interaction of TCE and DCE over Mn(x)Zr(1-x)O(2) catalysts depend strongly on manganese content. Thus, the adsorption strength of the reactants over the active sites is closely related with both the surface acidity and the accessibility of the lattice oxygen. A great influence of the specific interaction on the catalytic pattern has been also noticed. Since I(sp) depends on the redox properties, it has been proved that the specific interaction is determined by the presence of bulk Mn(3)O(4), which hinders the mobility of the oxygen lattice, and MnO(x), with the contrary effect. Finally, the selectivity to oxidation products has been correlated with both the enthalpy of adsorption and the specific interaction parameter, decreasing the selectivity to HCl with the increase of the enthalpy of adsorption.

  2. Structural, morphological, gas sensing and photocatalytic characterization of MoO3 and WO3 thin films prepared by the thermal vacuum evaporation technique

    NASA Astrophysics Data System (ADS)

    Arfaoui, A.; Touihri, S.; Mhamdi, A.; Labidi, A.; Manoubi, T.

    2015-12-01

    Thin films of molybdenum trioxide and tungsten trioxide were deposited on glass substrates using a simplified thermal evaporation under vacuum method monitored by heat treatment in flowing oxygen at 500 °C for 1 h. The structural and morphological properties of the films were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy. The X-ray diffraction analysis shows that the films of MoO3 and WO3 were well crystallized in orthorhombic and monoclinic phase respectively with the crystallites preferentially oriented toward (2 0 0) direction parallel a-axis for both samples. In literature, we have shown in previous papers that structural and surface morphology of metal thin films play an important role in the gas detection mechanism. In this article, we have studied the response evolution of MoO3 and WO3 thin films sensors ethanol versus time, working temperature and the concentration of the ethanol. It was found that these films had high sensitivity to ethanol, which made them as a good candidate for the ethanol sensor. Finally, the photocatalytic activity of the samples was evaluated with respect to the degradation reaction of a wastewater containing methylene blue (MB) under UV-visible light irradiation. The molybdenum trioxide exhibits a higher degradation rate than the tungsten trioxide thin films under similar experimental conditions.

  3. Determination of the triacylglycerol fraction in fish oil by comprehensive liquid chromatography techniques with the support of gas chromatography and mass spectrometry data.

    PubMed

    Beccaria, Marco; Costa, Rosaria; Sullini, Giuseppe; Grasso, Elisa; Cacciola, Francesco; Dugo, Paola; Mondello, Luigi

    2015-07-01

    Fish oil made from menhaden (Brevoortia tyrannus) can be used as a dietary supplement for the presence of high levels of the long-chained omega-3 fatty acids, viz. epentaenoic and docosahexanoic. In this work, for the first time, two different multidimensional approaches were developed and compared, in terms of peak capacity, for triacylglycerol characterization. In particular, silver ion chromatography with a silver-ion column and non-aqueous reverse-phase liquid chromatography with a C18 column were tested in both comprehensive (stop-flow) and off-line modes. The use of mass spectra attained by atmospheric pressure chemical ionization for both LC approaches, and the fatty acids methyl esters profile of menhaden oil obtained by gas chromatography analysis, greatly supported the elucidation of the triacylglycerol content in menhaden oil. The off-line approach afforded a better separation and, thus, higher peak capacity to allow identifying and semiquantifying more than 250 triacylglycerols. Such a huge number has never been reported for a menhaden oil sample.The main disadvantage of such an approach over the stop-flow one was the longer analysis time, mainly attributable to solvent exchange between the two dimensions. PMID:25963648

  4. Recent advances in experimental techniques to probe fast excited-state dynamics in biological molecules in the gas phase: dynamics in nucleotides, amino acids and beyond

    PubMed Central

    Staniforth, Michael; Stavros, Vasilios G.

    2013-01-01

    In many chemical reactions, an activation barrier must be overcome before a chemical transformation can occur. As such, understanding the behaviour of molecules in energetically excited states is critical to understanding the chemical changes that these molecules undergo. Among the most prominent reactions for mankind to understand are chemical changes that occur in our own biological molecules. A notable example is the focus towards understanding the interaction of DNA with ultraviolet radiation and the subsequent chemical changes. However, the interaction of radiation with large biological structures is highly complex, and thus the photochemistry of these systems as a whole is poorly understood. Studying the gas-phase spectroscopy and ultrafast dynamics of the building blocks of these more complex biomolecules offers the tantalizing prospect of providing a scientifically intuitive bottom-up approach, beginning with the study of the subunits of large polymeric biomolecules and monitoring the evolution in photochemistry as the complexity of the molecules is increased. While highly attractive, one of the main challenges of this approach is in transferring large, and in many cases, thermally labile molecules into vacuum. This review discusses the recent advances in cutting-edge experimental methodologies, emerging as excellent candidates for progressing this bottom-up approach. PMID:24204191

  5. Recent advances in experimental techniques to probe fast excited-state dynamics in biological molecules in the gas phase: dynamics in nucleotides, amino acids and beyond.

    PubMed

    Staniforth, Michael; Stavros, Vasilios G

    2013-11-01

    In many chemical reactions, an activation barrier must be overcome before a chemical transformation can occur. As such, understanding the behaviour of molecules in energetically excited states is critical to understanding the chemical changes that these molecules undergo. Among the most prominent reactions for mankind to understand are chemical changes that occur in our own biological molecules. A notable example is the focus towards understanding the interaction of DNA with ultraviolet radiation and the subsequent chemical changes. However, the interaction of radiation with large biological structures is highly complex, and thus the photochemistry of these systems as a whole is poorly understood. Studying the gas-phase spectroscopy and ultrafast dynamics of the building blocks of these more complex biomolecules offers the tantalizing prospect of providing a scientifically intuitive bottom-up approach, beginning with the study of the subunits of large polymeric biomolecules and monitoring the evolution in photochemistry as the complexity of the molecules is increased. While highly attractive, one of the main challenges of this approach is in transferring large, and in many cases, thermally labile molecules into vacuum. This review discusses the recent advances in cutting-edge experimental methodologies, emerging as excellent candidates for progressing this bottom-up approach.

  6. Gas chromatography in space.

    PubMed

    Akapo, S O; Dimandja, J M; Kojiro, D R; Valentin, J R; Carle, G C

    1999-05-28

    Gas chromatography has proven to be a very useful analytical technique for in situ analysis of extraterrestrial environments as demonstrated by its successful operation on spacecraft missions to Mars and Venus. The technique is also one of the six scientific instruments aboard the Huygens probe to explore Titan's atmosphere and surface. A review of gas chromatography in previous space missions and some recent developments in the current environment of fiscal constraints and payload size limitations are presented.

  7. Gas chromatography in space

    NASA Technical Reports Server (NTRS)

    Akapo, S. O.; Dimandja, J. M.; Kojiro, D. R.; Valentin, J. R.; Carle, G. C.

    1999-01-01

    Gas chromatography has proven to be a very useful analytical technique for in situ analysis of extraterrestrial environments as demonstrated by its successful operation on spacecraft missions to Mars and Venus. The technique is also one of the six scientific instruments aboard the Huygens probe to explore Titan's atmosphere and surface. A review of gas chromatography in previous space missions and some recent developments in the current environment of fiscal constraints and payload size limitations are presented.

  8. Active cleaning technique device

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    The objective of this program was to develop a laboratory demonstration model of an active cleaning technique (ACT) device. The principle of this device is based primarily on the technique for removing contaminants from optical surfaces. This active cleaning technique involves exposing contaminated surfaces to a plasma containing atomic oxygen or combinations of other reactive gases. The ACT device laboratory demonstration model incorporates, in addition to plasma cleaning, the means to operate the device as an ion source for sputtering experiments. The overall ACT device includes a plasma generation tube, an ion accelerator, a gas supply system, a RF power supply and a high voltage dc power supply.

  9. Spectroscopic Techniques for Atmospheric Analysis

    SciTech Connect

    Bililign, Solomon

    2009-07-06

    Several analytical and optical techniques for atmospheric analysis are discussed. Environmental constraints for real world applications are mentioned. Special emphasis is given to the cavity ring Down Spectroscopy as a very sensitive method for atmospheric trace gas detection is described.

  10. Short communication: Use of a portable, automated, open-circuit gas quantification system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions in Holstein cows fed ad libitum or restricted.

    PubMed

    Dorich, C D; Varner, R K; Pereira, A B D; Martineau, R; Soder, K J; Brito, A F

    2015-04-01

    The objective of this study was to measure enteric CH4 emissions using a new portable automated open-circuit gas quantification system (GQS) and the sulfur hexafluoride tracer technique (SF6) in midlactation Holstein cows housed in a tiestall barn. Sixteen cows averaging 176 ± 34 d in milk, 40.7 ± 6.1 kg of milk yield, and 685 ± 49 kg of body weight were randomly assigned to 1 out of 2 treatments according to a crossover design. Treatments were (1) ad libitum (adjusted daily to yield 10% orts) and (2) restricted feed intake [set to restrict feed by 10% of baseline dry matter intake (DMI)]. Each experimental period lasted 22d, with 14 d for treatment adaptation and 8d for data and sample collection. A common diet was fed to the cows as a total mixed ration and contained 40.4% corn silage, 11.2% grass-legume haylage, and 48.4% concentrate on a dry matter basis. Spot 5-min measurements using the GQS were taken twice daily with a 12-h interval between sampling and sampling times advanced 2h daily to account for diurnal variation in CH4 emissions. Canisters for the SF6 method were sampled twice daily before milking with 4 local background gas canisters inside the barn analyzed for background gas concentrations. Enteric CH4 emissions were not affected by treatments and averaged 472 and 458 g/d (standard error of the mean = 18 g/d) for ad libitum and restricted intake treatments, respectively (data not shown). The GQS appears to be a reliable method because of the relatively low coefficients of variation (ranging from 14.1 to 22.4%) for CH4 emissions and a moderate relationship (coefficient of determination = 0.42) between CH4 emissions and DMI. The SF6 resulted in large coefficients of variation (ranging from 16.0 to 111%) for CH4 emissions and a poor relationship (coefficient of determination = 0.17) between CH4 emissions and DMI, likely because of limited barn ventilation and high background gas concentration. Research with improved barn ventilation systems or

  11. Short communication: Use of a portable, automated, open-circuit gas quantification system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions in Holstein cows fed ad libitum or restricted.

    PubMed

    Dorich, C D; Varner, R K; Pereira, A B D; Martineau, R; Soder, K J; Brito, A F

    2015-04-01

    The objective of this study was to measure enteric CH4 emissions using a new portable automated open-circuit gas quantification system (GQS) and the sulfur hexafluoride tracer technique (SF6) in midlactation Holstein cows housed in a tiestall barn. Sixteen cows averaging 176 ± 34 d in milk, 40.7 ± 6.1 kg of milk yield, and 685 ± 49 kg of body weight were randomly assigned to 1 out of 2 treatments according to a crossover design. Treatments were (1) ad libitum (adjusted daily to yield 10% orts) and (2) restricted feed intake [set to restrict feed by 10% of baseline dry matter intake (DMI)]. Each experimental period lasted 22d, with 14 d for treatment adaptation and 8d for data and sample collection. A common diet was fed to the cows as a total mixed ration and contained 40.4% corn silage, 11.2% grass-legume haylage, and 48.4% concentrate on a dry matter basis. Spot 5-min measurements using the GQS were taken twice daily with a 12-h interval between sampling and sampling times advanced 2h daily to account for diurnal variation in CH4 emissions. Canisters for the SF6 method were sampled twice daily before milking with 4 local background gas canisters inside the barn analyzed for background gas concentrations. Enteric CH4 emissions were not affected by treatments and averaged 472 and 458 g/d (standard error of the mean = 18 g/d) for ad libitum and restricted intake treatments, respectively (data not shown). The GQS appears to be a reliable method because of the relatively low coefficients of variation (ranging from 14.1 to 22.4%) for CH4 emissions and a moderate relationship (coefficient of determination = 0.42) between CH4 emissions and DMI. The SF6 resulted in large coefficients of variation (ranging from 16.0 to 111%) for CH4 emissions and a poor relationship (coefficient of determination = 0.17) between CH4 emissions and DMI, likely because of limited barn ventilation and high background gas concentration. Research with improved barn ventilation systems or

  12. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    NASA Astrophysics Data System (ADS)

    Sgouridis, F.; Ullah, S.; Stott, A.

    2015-08-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Pre-concentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. For our chamber design (volume / surface = 8:1) and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. The N2 flux ranged between 2.4 and 416.6 μg N m-2 h-1, and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N2O flux was on average 20 to 200 times lower than the N2 flux, while the denitrification product ratio (N2O/N2 + N2O) was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique under the same field conditions

  13. Longitudinal displacement of the carotid wall and cardiovascular risk factors: associations with aging, adiposity, blood pressure and periodontal disease independent of cross-sectional distensibility and intima-media thickness.

    PubMed

    Zahnd, Guillaume; Vray, Didier; Sérusclat, André; Alibay, Djhianne; Bartold, Mark; Brown, Alex; Durand, Marion; Jamieson, Lisa M; Kapellas, Kostas; Maple-Brown, Louise J; O'Dea, Kerin; Moulin, Philippe; Celermajer, David S; Skilton, Michael R

    2012-10-01

    The recently discovered longitudinal displacement of the common carotid arterial wall (i.e., the motion along the same plane as the blood flow), may be associated with incident cardiovascular events and represents a novel and relevant clinical information. At present, there have only been a few studies that have been conducted to investigate this longitudinal movement. We propose here a method to assess noninvasively the wall bi-dimensional (two-dimensional [2-D], cross-sectional and longitudinal) motion and present an original approach that combines a robust speckle tracking scheme to guidance by minimal path contours segmentation. Our method is well suited to large clinical population studies as it does not necessitate strong imaging prerequisites. The aim of this study is to describe the association between the longitudinal displacement of the carotid arterial wall and cardiovascular risk factors, among which periodontal disease. Some 126 Indigenous Australians with periodontal disease, an emerging risk factor, and 27 healthy age- and sex-matched non-indigenous control subjects had high-resolution ultrasound scans of the common carotid artery. Carotid intima-media thickness and arterial wall 2-D motion were then assessed using our method in ultrasound B-mode sequences. Carotid longitudinal displacement was markedly lower in the periodontal disease group than the control group (geometric mean (IQR): 0.15 mm (0.13) vs. 0.42 mm (0.30), respectively; p < 0.0001), independent of cardiovascular risk factors, cross-sectional distensibility and carotid intima-media thickness (p < 0.0001). A multivariable model indicated that the strongest correlates of carotid longitudinal displacement in adults with periodontal disease were age (β-coefficient = -.235, p = .03), waist (β-coefficient = -.357, p = 0.001), and pulse pressure (β-coefficient = .175, p = 0.07), independent of other cardiovascular risk factors, cross-sectional distensibility and pulse wave velocity. Carotid

  14. Residual gas analyzer calibration

    NASA Technical Reports Server (NTRS)

    Lilienkamp, R. H.

    1972-01-01

    A technique which employs known gas mixtures to calibrate the residual gas analyzer (RGA) is described. The mass spectra from the RGA are recorded for each gas mixture. This mass spectra data and the mixture composition data each form a matrix. From the two matrices the calibration matrix may be computed. The matrix mathematics requires the number of calibration gas mixtures be equal to or greater than the number of gases included in the calibration. This technique was evaluated using a mathematical model of an RGA to generate the mass spectra. This model included shot noise errors in the mass spectra. Errors in the gas concentrations were also included in the valuation. The effects of these errors was studied by varying their magnitudes and comparing the resulting calibrations. Several methods of evaluating an actual calibration are presented. The effects of the number of gases in then, the composition of the calibration mixture, and the number of mixtures used are discussed.

  15. Effect of changes in intra-abdominal pressure on diameter, cross-sectional area, and distensibility of the lower esophageal sphincter of healthy dogs as determined by use of an endoscopic functional luminal imaging probe.

    PubMed

    Mayhew, Philipp D; Pitt, Kathryn A; Steffey, Michele A; Culp, William T N; Kass, Philip H; Marks, Stanley L

    2016-08-01

    OBJECTIVE To evaluate the effect of intra-abdominal pressure (IAP) on morphology and compliance of the lower esophageal sphincter (LES) by use of impedance planimetry in healthy dogs and to quantify the effect of changes in IAP. ANIMALS 7 healthy, purpose-bred sexually intact male hound-cross dogs. PROCEDURES Dogs were anesthetized, and cross-sectional area (CSA), minimal diameter (MD), LES length, LES volume, and distensibility index (DI) of the LES were evaluated by use of an endoscopic functional luminal imaging probe. For each dog, measurements were obtained before (baseline) and after creation of a pneumoperitoneum at an IAP of 4, 8, and 15 mm Hg. Order of the IAPs was determined by use of a randomization software program. RESULTS CSA and MD at 4 and 8 mm Hg were not significantly different from baseline measurements; however, CSA and MD at 15 mm Hg were both significantly greater than baseline measurements. The LES length and LES volume did not differ significantly from baseline measurements at any IAP. The DI differed inconsistently from the baseline measurement but was not substantially affected by IAP. CONCLUSIONS AND CLINICAL RELEVANCE Pneumoperitoneum created with an IAP of 4 or 8 mm Hg did not significantly alter LES morphology in healthy dogs. Pneumoperitoneum at an IAP of 15 mm Hg caused a significant increase in CSA and MD of the LES. Compliance of the LES as measured by the DI was not greatly altered by pneumoperitoneum at an IAP of up to 15 mm Hg. PMID:27463542

  16. Dismantling techniques

    SciTech Connect

    Wiese, E.

    1998-03-13

    Most of the dismantling techniques used in a Decontamination and Dismantlement (D and D) project are taken from conventional demolition practices. Some modifications to the techniques are made to limit exposure to the workers or to lessen the spread of contamination to the work area. When working on a D and D project, it is best to keep the dismantling techniques and tools as simple as possible. The workers will be more efficient and safer using techniques that are familiar to them. Prior experience with the technique or use of mock-ups is the best way to keep workers safe and to keep the project on schedule.

  17. Application of linear multivariate calibration techniques to identify the peaks responsible for the antioxidant activity of Satureja hortensis L. and Oliveria decumbens Vent. essential oils by gas chromatography-mass spectrometry.

    PubMed

    Samadi, Naser; Masoum, Saeed; Mehrara, Bahare; Hosseini, Hossein

    2015-09-15

    Satureja hortensis L. and Oliveria decumbens Vent. are known for their diverse effects in drug therapy and traditional medicine. One of the most interesting properties of their essential oils is good antioxidant activity. In this paper, essential oils of aerial parts of S. hortensis L. and O. decumbens Vent. from different regions were obtained by hydrodistillation and were analyzed by gas chromatography-mass spectrometry (GC-MS). Essential oils were tested for their free radical scavenging activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to identify the peaks potentially responsible for the antioxidant activity from chromatographic fingerprints by numerous linear multivariate calibration techniques. Because of its simplicity and high repeatability, orthogonal projection to latent structures (OPLS) model had the best performance in indicating the potential antioxidant compounds in S. hortensis L. and O. decumbens Vent. essential oils. In this study, P-cymene, carvacrol and β-bisabolene for S. hortensis L. and P-cymene, Ç-terpinen, thymol, carvacrol, and 1,3-benzodioxole, 4-methoxy-6-(2-propenyl) for O. decumbens Vent. are suggested as the potentially antioxidant compounds. PMID:26262598

  18. Application of linear multivariate calibration techniques to identify the peaks responsible for the antioxidant activity of Satureja hortensis L. and Oliveria decumbens Vent. essential oils by gas chromatography-mass spectrometry.

    PubMed

    Samadi, Naser; Masoum, Saeed; Mehrara, Bahare; Hosseini, Hossein

    2015-09-15

    Satureja hortensis L. and Oliveria decumbens Vent. are known for their diverse effects in drug therapy and traditional medicine. One of the most interesting properties of their essential oils is good antioxidant activity. In this paper, essential oils of aerial parts of S. hortensis L. and O. decumbens Vent. from different regions were obtained by hydrodistillation and were analyzed by gas chromatography-mass spectrometry (GC-MS). Essential oils were tested for their free radical scavenging activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to identify the peaks potentially responsible for the antioxidant activity from chromatographic fingerprints by numerous linear multivariate calibration techniques. Because of its simplicity and high repeatability, orthogonal projection to latent structures (OPLS) model had the best performance in indicating the potential antioxidant compounds in S. hortensis L. and O. decumbens Vent. essential oils. In this study, P-cymene, carvacrol and β-bisabolene for S. hortensis L. and P-cymene, Ç-terpinen, thymol, carvacrol, and 1,3-benzodioxole, 4-methoxy-6-(2-propenyl) for O. decumbens Vent. are suggested as the potentially antioxidant compounds.

  19. Remote Raman measurement techniques

    NASA Technical Reports Server (NTRS)

    Leonard, D. A.

    1981-01-01

    The use of laser Raman measurement techniques in remote sensing applications is surveyed. A feasibility index is defined as a means to characterize the practicality of a given remote Raman measurement application. Specific applications of Raman scattering to the measurement of atmospheric water vapor profiles, methane plumes from liquid natural gas spills, and subsurface ocean temperature profiles are described. This paper will survey the use of laser Raman measurement techniques in remote sensing applications using as examples specific systems that the Computer Genetics Corporation (CGC) group has developed and engineered.

  20. Gas Interference in Sucker Rod Pump

    NASA Astrophysics Data System (ADS)

    Samad, Abdus

    2010-10-01

    Commonly used artificial lift or dewatering system is sucker rod pump and gas interference of the pump is the biggest issue in the oil and gas industry. Gas lock or fluid pound problems occur due to the gas interference when the pump has partially or completely unfilled plunger barrel. There are several techniques available in the form of patents to solve these problems but those techniques have positive as well as negative aspects. Some of the designs rely on the leakage and some of the designs rely on the mechanical arrangements etc to break the gas lock. The present article compares the existing gas interference handling techniques.

  1. The feasibility of computational modelling technique to detect the bladder cancer.

    PubMed

    Keshtkar, Ahmad; Mesbahi, Asghar; Rasta, S H; Keshtkar, Asghar

    2010-01-01

    A numerical technique, finite element analysis (FEA) was used to model the electrical properties, the bio impedance of the bladder tissue in order to predict the bladder cancer. This model results showed that the normal bladder tissue have significantly higher impedance than the malignant tissue that was in opposite with the impedance measurements or the experimental results. Therefore, this difference can be explained using the effects of inflammation, oedema on the urothelium and the property of the bladder as a distensible organ. Furthermore, the different current distributions inside the bladder tissue (in histological layers) in normal and malignant cases and finally different applied pressures over the bladder tissue can cause different impedances for the bladder tissue. Finally, it is believed that further studies have to be carried out to characterise the human bladder tissue using the electrical impedance measurement and modelling techniques.

  2. Development of a new Laser Photofragmentation/Fluorescent Assay by Gas Expansion (LP/FAGE) technique for the quantification of tropospheric nitrous acid (HONO) at low parts-per-trillion mixing ratios

    NASA Astrophysics Data System (ADS)

    Mielke, L. H.; Lew, M.; Bottorff, B.; Berke, A.; Raff, J. D.; Stevens, P. S.; Dusanter, S.

    2013-12-01

    Determining the full oxidative capacity of the atmosphere is vital to understanding the production of secondary pollutants such as ozone and secondary organic aerosols and for regulating the lifetime of pollutants leading to climate change. The hydroxyl radical is the primary oxidant of volatile organic compounds (VOCs) in the troposphere. Nocturnal nitrous acid (HONO) is an important radical reservoir species and releases OH upon photolysis the next morning. In addition, recent studies have indicated higher than expected mixing ratios of HONO in the daytime. As daytime HONO mixing ratios usually maximize at only a couple hundred part-per-trillion, it is important to have a technique that is accurate, sensitive, and precise. Here we outline an instrumental technique called Laser Photofragmention/Fluorescent Assay by Gas Expansion (LP/FAGE). Ambient air is drawn through an inlet composed of a 1' diameter metal disk with a 0.025' cylindrically bored hole where it undergoes expansion into a cell held at ~3 torr. Fiber coupled laser emission (YILF: 355 nm, 2.2 W) induces photofragmentation of HONO to OH and NO whereby the OH is quantified by the FAGE technique using a fiber coupled 308 nm (6 mW) laser emission. The 355 nm and 308 nm emission are single pass, collinear, and separated only by the time delay of the pulses. To differentiate ambient OH from HONO-generated-OH, a shutter is used to block the 355 nm laser emission for a given period of time. Fluorescence from OH vs. fluorescence from interfering species can be differentiated by scanning on and off a specific rovibronic feature in the OH absorbance spectra. In this presentation we outline the instrumental technique, including its calibration in which effluent from an HCl permeation device is humidified and passed over a bed of sodium nitrate coated glass beads. The calibrator output is varied from 1 to several tens of parts-per-billions (ppb) and is detected using a chemiluminescence NOx analyzer. The

  3. Safer Liquid Natural Gas

    NASA Technical Reports Server (NTRS)

    1976-01-01

    After the disaster of Staten Island in 1973 where 40 people were killed repairing a liquid natural gas storage tank, the New York Fire Commissioner requested NASA's help in drawing up a comprehensive plan to cover the design, construction, and operation of liquid natural gas facilities. Two programs are underway. The first transfers comprehensive risk management techniques and procedures which take the form of an instruction document that includes determining liquid-gas risks through engineering analysis and tests, controlling these risks by setting up redundant fail safe techniques, and establishing criteria calling for decisions that eliminate or accept certain risks. The second program prepares a liquid gas safety manual (the first of its kind).

  4. Halogen speciation in volcanic plumes - Development of compact denuder sampling techniques with in-situ derivatization followed by gas chromatography-mass spectrometry and their application at Mt. Etna, Mt. Nyiragongo and Mt. Nyamulagira in 2015.

    NASA Astrophysics Data System (ADS)

    Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

    2016-04-01

    products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography-mass spectrometry gives a limit of detection below 1 ng of bromine. The method was applied in 2015 on volcanic gas plumes at Mt. Etna (Italy), Mt. Nyiragongo and Mt. Nyamulagira (DR Congo) giving reactive bromine mixing ratios from 0.3 ppb (Nyiragongo) up to 22 ppb (Etna, NEC). Compared with total halogen data derived by alkaline trap sampling (Raschig-tube) and ion-chromatography analysis the reactive bromine mixing ratios allow the investigation of the conversion of HBr into reactive species due to plume chemistry with progressing plume age. The new method will be described in detail and the first results on the reactive halogen to total halogen output will be discussed (for bromine and chlorine) and compared to earlier volcanic plume chemistry model studies. References Bobrowski, N. and G. Giuffrida: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009. Solid Earth, 3, 433-445, 2012 Bobrowski, N., R. von Glasow, A. Aiuppa, S. Inguaggiato, I. Louban, O. W. Ibrahim and U. Platt: Reactive halogen chemistry in volcanic plumes. J. Geophys. Res., 112, 2007 Donovan A., V. Tsanev, C. Oppenheimer and M. Edmonds: Reactive halogens (BrO and OClO) detected in the plume of Soufrière Hills Volcano during an eruption hiatus. Geochem. Geophys. Geosyst., 15, 3346-3363, 2014 Rüdiger, J., N. Bobrowski, T. Hoffmann (2015), Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes (EGU2015-2392-2), EGU General Assembly 2015

  5. One-step multiple component isolation from the oil of Crinitaria tatarica (Less.) Sojak. by preparative capillary gas with characterization by spectroscopic and spectrometric techniques and evaluation of biological activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the present work multiple component isolation from the oil of Crinitaria tatarica (Less.) Sojak. by Preparative Capillary Gas Chromatography (PCGC) with characterization by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy have been carried out. Gas chromatography (GC-FID) ...

  6. Decomposition techniques

    USGS Publications Warehouse

    Chao, T.T.; Sanzolone, R.F.

    1992-01-01

    Sample decomposition is a fundamental and integral step in the procedure of geochemical analysis. It is often the limiting factor to sample throughput, especially with the recent application of the fast and modern multi-element measurement instrumentation. The complexity of geological materials makes it necessary to choose the sample decomposition technique that is compatible with the specific objective of the analysis. When selecting a decomposition technique, consideration should be given to the chemical and mineralogical characteristics of the sample, elements to be determined, precision and accuracy requirements, sample throughput, technical capability of personnel, and time constraints. This paper addresses these concerns and discusses the attributes and limitations of many techniques of sample decomposition along with examples of their application to geochemical analysis. The chemical properties of reagents as to their function as decomposition agents are also reviewed. The section on acid dissolution techniques addresses the various inorganic acids that are used individually or in combination in both open and closed systems. Fluxes used in sample fusion are discussed. The promising microwave-oven technology and the emerging field of automation are also examined. A section on applications highlights the use of decomposition techniques for the determination of Au, platinum group elements (PGEs), Hg, U, hydride-forming elements, rare earth elements (REEs), and multi-elements in geological materials. Partial dissolution techniques used for geochemical exploration which have been treated in detail elsewhere are not discussed here; nor are fire-assaying for noble metals and decomposition techniques for X-ray fluorescence or nuclear methods be discussed. ?? 1992.

  7. Use of Cutting-Edge Horizontal and Underbalanced Drilling Technologies and Subsurface Seismic Techniques to Explore, Drill and Produce Reservoired Oil and Gas from the Fractured Monterey Below 10,000 ft in the Santa Maria Basin of California

    SciTech Connect

    George Witter; Robert Knoll; William Rehm; Thomas Williams

    2005-09-29

    This project was undertaken to demonstrate that oil and gas can be drilled and produced safely and economically from a fractured Monterey reservoir in the Santa Maria Basin of California by employing horizontal wellbores and underbalanced drilling technologies. Two vertical wells were previously drilled in this area with heavy mud and conventional completions; neither was commercially productive. A new well was drilled by the project team in 2004 with the objective of accessing an extended length of oil-bearing, high-resistivity Monterey shale via a horizontal wellbore, while implementing managed-pressure drilling (MPD) techniques to avoid formation damage. Initial project meetings were conducted in October 2003. The team confirmed that the demonstration well would be completed open-hole to minimize productivity impairment. Following an overview of the geologic setting and local field experience, critical aspects of the application were identified. At the pre-spud meeting in January 2004, the final well design was confirmed and the well programming/service company requirements assigned. Various design elements were reduced in scope due to significant budgetary constraints. Major alterations to the original plan included: (1) a VSP seismic survey was delayed to a later phase; (2) a new (larger) surface hole would be drilled rather than re-enter an existing well; (3) a 7-in. liner would be placed into the top of the Monterey target as quickly as possible to avoid problems with hole stability; (4) evaluation activities were reduced in scope; (5) geosteering observations for fracture access would be deduced from penetration rate, cuttings description and hydrocarbon in-flow; and (6) rather than use nitrogen, a novel air-injection MPD system was to be implemented. Drilling operations, delayed from the original schedule by capital constraints and lack of rig availability, were conducted from September 12 to November 11, 2004. The vertical and upper curved sections were

  8. Use of Cutting-Edge Horizontal and Underbalanced Drilling Technologies and Subsurface Seismic Techniques to Explore, Drill and Produce Reservoired Oil and Gas from the Fractured Monterey Below 10,000 ft in the Santa Maria Basin of California

    SciTech Connect

    George Witter; Robert Knoll; William Rehm; Thomas Williams

    2006-06-30

    This project was undertaken to demonstrate that oil and gas can be drilled and produced safely and economically from a fractured Monterey reservoir in the Santa Maria Basin of California by employing horizontal wellbores and underbalanced drilling technologies. Two vertical wells were previously drilled in this area with heavy mud and conventional completions; neither was commercially productive. A new well was drilled by the project team in 2004 with the objective of accessing an extended length of oil-bearing, high-resistivity Monterey shale via a horizontal wellbore, while implementing managed-pressure drilling (MPD) techniques to avoid formation damage. Initial project meetings were conducted in October 2003. The team confirmed that the demonstration well would be completed open-hole to minimize productivity impairment. Following an overview of the geologic setting and local field experience, critical aspects of the application were identified. At the pre-spud meeting in January 2004, the final well design was confirmed and the well programming/service company requirements assigned. Various design elements were reduced in scope due to significant budgetary constraints. Major alterations to the original plan included: (1) a VSP seismic survey was delayed to a later phase; (2) a new (larger) surface hole would be drilled rather than re-enter an existing well; (3) a 7-in. liner would be placed into the top of the Monterey target as quickly as possible to avoid problems with hole stability; (4) evaluation activities were reduced in scope; (5) geosteering observations for fracture access would be deduced from penetration rate, cuttings description and hydrocarbon in-flow; and (6) rather than use nitrogen, a novel air-injection MPD system was to be implemented. Drilling operations, delayed from the original schedule by capital constraints and lack of rig availability, were conducted from September 12 to November 11, 2004. The vertical and upper curved sections were

  9. USE OF CUTTING-EDGE HORIZONTAL AND UNDERBALANCED DRILLING TECHNOLOGIES AND SUBSURFACE SEISMIC TECHNIQUES TO EXPLORE, DRILL AND PRODUCE RESERVOIRED OIL AND GAS FROM THE FRACTURED MONTEREY BELOW 10,000 FT IN THE SANTA MARIA BASIN OF CALIFORNIA

    SciTech Connect

    George Witter; Robert Knoll; William Rehm; Thomas Williams

    2005-02-01

    This project was undertaken to demonstrate that oil and gas can be drilled and produced safely and economically from a fractured Monterey reservoir in the Santa Maria Basin of California by employing horizontal wellbores and underbalanced drilling technologies. Two vertical wells were previously drilled in this area by Temblor Petroleum with heavy mud and conventional completions; neither was commercially productive. A new well was drilled by the project team in 2004 with the objective of accessing an extended length of oil-bearing, high-resistivity Monterey shale via a horizontal wellbore, while implementing managed-pressure drilling (MPD) techniques to avoid formation damage. Initial project meetings were conducted in October 2003. The team confirmed that the demonstration well would be completed open-hole to minimize productivity impairment. Following an overview of the geologic setting and local field experience, critical aspects of the application were identified. At the pre-spud meeting in January 2004, the final well design was confirmed and the well programming/service company requirements assigned. Various design elements were reduced in scope due to significant budgetary constraints. Major alterations to the original plan included: (1) a VSP seismic survey was delayed to a later phase; (2) a new (larger) surface hole would be drilled rather than re-enter an existing well; (3) a 7-in. liner would be placed into the top of the Monterey target as quickly as possible to avoid problems with hole stability; (4) evaluation activities were reduced in scope; (5) geosteering observations for fracture access would be deduced from penetration rate, cuttings description and hydrocarbon in-flow; and (6) rather than use nitrogen, a novel air-injection MPD system was to be implemented. Drilling operations, delayed from the original schedule by capital constraints and lack of rig availability, were conducted from September 12 to November 11, 2004. The vertical and upper

  10. Miscellaneous Techniques

    NASA Astrophysics Data System (ADS)

    Jha, Shyam N.

    Nondestructive way of determining the food quality is the need of the hour. Till now major methods such as colour measurements and their modeling; machine vision systems; X-ray, CT and MRI; NIR spectroscopy; electronic nose and tongue; and ultrasonic technology have been discussed in detail. These techniques, in general, are considered to be sophisticated and costly, and therefore probably are not being adopted as fast as it should be. I am however of the reverse opinion. While going through these techniques, it has been seen that majority of quality parameters have been measured and correlated with the signals obtained using different equipment.

  11. Gas gangrene

    MedlinePlus

    Tissue infection - Clostridial; Gangrene - gas; Myonecrosis; Clostridial infection of tissues; Necrotizing soft tissue infection ... Gas gangrene is most often caused by bacteria called Clostridium perfringens. It also can be caused by ...

  12. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  13. Gas separating

    DOEpatents

    Gollan, Arye Z. [Newton, MA

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  14. Remote Leak Detection: Indirect Thermal Technique

    NASA Technical Reports Server (NTRS)

    Clements, Sandra

    2002-01-01

    Remote sensing technologies are being considered for efficient, low cost gas leak detection. Eleven specific techniques have been identified for further study and evaluation of several of these is underway. The Indirect Thermal Technique is one of the techniques that is being explored. For this technique, an infrared camera is used to detect the temperature change of a pipe or fitting at the site of a gas leak. This temperature change is caused by the change in temperature of the gas expanding from the leak site. During the 10-week NFFP program, the theory behind the technique was further developed, experiments were performed to determine the conditions for which the technique might be viable, and a proof-of-concept system was developed and tested in the laboratory.

  15. Selected microgravity combustion diagnostic techniques

    NASA Technical Reports Server (NTRS)

    Griffin, Devon W.; Greenberg, Paul S.

    1993-01-01

    During FY 1989-1992, several diagnostic techniques for studying microgravity combustion have moved from the laboratory to use in reduced-gravity facilities. This paper discusses current instrumentation for rainbow schlieren deflectometry and thermophoretic sampling of soot from gas jet diffusion flames.

  16. Electrochemical Techniques

    SciTech Connect

    Chen, Gang; Lin, Yuehe

    2008-07-20

    Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.

  17. Pulse waveform analysis of arterial compliance: relation to other techniques, age, and metabolic variables.

    PubMed

    Resnick, L M; Militianu, D; Cunnings, A J; Pipe, J G; Evelhoch, J L; Soulen, R L; Lester, M A

    2000-12-01

    To assess the physiologic and clinical relevance of newer noninvasive measures of vascular compliance, computerized arterial pulse waveform analysis (CAPWA) of the radial pulse was used to calculate two components of compliance, C1 (capacitive) and C2 (oscillatory or reflective), in 87 normotensive (N1BP, n = 20), untreated hypertensive (HiBP, n = 21), and treated hypertensive (HiBP-Rx, n = 46) subjects. These values were compared with two other indices of compliance, the ratio of stroke volume to pulse pressure (SV/PP) and magnetic resonance imaging (MRI)-based aortic distensibility; and were also correlated with demographic and biochemical values. The HiBP subjects displayed lower C1 (1.34 +/- 0.09 v. 1.70 +/- 0.11 mL/mm Hg, significance [sig] = .05) and C2 (0.031 +/- 0.003 v 0.073 +/- 0.02 mL/mm Hg, sig = .005) than N1BP subjects. This was not true for C1 (1.64 +/- 0.08 mL/mm Hg) and C2 (0.052 +/- 0.005 mL/mm Hg) values in HiBP-Rx subjects. The C1 (r = 0.917, P < .0001) and C2 (r = 0.677, P < .0001) were both closely related to SV/PP, whereas C1 (r = 0.748, P = .002), but not C2, was significantly related to MRI-determined aortic distensibility. Among other factors measured, age exerted a strong negative influence on both C1 (r = -0.696, P < .0001) and C2 (r = -0.611, P < .0001) compliance components. Positive correlations were observed between C1 (r = 0.863, P = .006), aortic distensibility (r = 0.597, P = .19) and 24-h urinary sodium excretion, and between C1- and MR spectroscopy-determined in situ skeletal muscle intracellular free magnesium (r = 0.827, P = .006), whereas C2 was inversely related to MRI-determined abdominal visceral fat area (r = -0.512, P = .042) and fasting blood glucose (r = -0.846, P = .001). Altogether, the close correspondence between CAPWA, other compliance techniques, and known cardiovascular risk factors suggests the clinical relevance of CAPWA in the assessment of altered vascular function in hypertension. PMID:11130766

  18. Gas Blowing: Mass Transfer in Gas and Melt

    NASA Astrophysics Data System (ADS)

    Sortland, Øyvind Sunde; Tangstad, Merete

    2014-09-01

    Metallurgical routes for solar grade silicon production are being developed as alternatives to chemical processes for their potential to achieve cost reductions, increased production volume, and reduced environmental and safety concerns. An important challenge in the development of metallurgical routes relates to the higher impurity concentrations in the silicon product, particularly for boron and other elements that are not efficiently segregated in solidification techniques. The reactive gas refining process is studied for its potential to remove boron below the solar grade silicon target concentration in a single step by blowing steam and hydrogen gas jets onto the melt surface. Boron in a silicon melt is extracted to HBO gas in parallel to active oxidation of silicon. The literature is not unified regarding the rate determining step in this process. Relevant theories and equations for gas blowing in induction furnaces are combined and used to explain mass transfer in experiments. Mass transfer in the melt and gas is investigated by comparing resistance and induction heating of the melt, and varying gas flow rate, crucible diameter, diameter of the gas lance, and the position of the gas lance above the melt surface. The rate of boron removal is found to increase with increasing gas flow rate and crucible diameter. A relatively high fraction of the reactive gas is utilized in the process, and supply of steam in the bulk gas is the only identified rate determining step.

  19. Western Gas Sands Subprogram

    SciTech Connect

    Not Available

    1983-12-01

    The Western Gas Sands Subprogram (WGSS) is a multidisciplinary research effort within the US Department of Energy program on Unconventional Gas Recovery. The subprogram, managed by DOE's Morgantown Energy Technology Center, is directed towards the development of tight (very low permeability) lenticular gas sands in the western United States. The purpose of the subprogram is to demonstrate the feasibility of economically producing natural gas from low-permeability reservoirs. The subprogram has two broad goals: (1) to reduce the uncertainty of the reservoir production potential and (2) to improve the extraction technology. With input from the gas industry, universities, and geologic and engineering consulting firms, the WGSS was broadened to include more fundamental research and development. Consequently, for the last five years it has focused on improving diagnostic instrumentation, geophysical and engineering interpretation, and stimulation techniques. Integrated geologic studies of the three priority basins containing tight sands and selected by DOE as research targets have also been pursued as part of this new effort. To date, the following tentative conclusions have evolved: Permeability of the tight gas sands can be as much as three to four orders of magnitude lower than conventional gas deposits. Nineteen western geologic basins and trends containing significant amounts of tight gas have been identified. Gas resources in the priority geologic basins are Piceance Basin, 49 tcf., Uinta Basin, 20 tcf., and Greater Green River Basin, 136 tcf. The presence of natural micro-fractures within the production zone of a reservoir and the effective propped length of hydraulically-induced fractures are the critical parameters for successful development of tight sand resources. 8 figures.

  20. Western gas sands

    SciTech Connect

    Not Available

    1985-03-01

    The purpose of this research is to demonstrate the feasibility of economically producing natural gas from low-permeability reservoirs. Two broad research goals have been defined: (1) reducing the uncertainty of the reservoir production potential, and (2) improving the extraction technology. These goals are being pursued by conducting research and encouraging industrial efforts in developing the necessary technology, including: (1) providing fundamental research into the nature of tight, lenticular gas sands and the technologies for diagnosing and developing them: (2) developing and verifying the technology for effective gas production; and (3) promoting the transfer of research products and technology advances to the gas industry in usable forms. The focus of the research for the last several years has been improving diagnostic instrumentation for reservoir and stimulation performance evaluation, geophysical and engineering interpretation, and stimulation techniques. Integrated geologic studies of three basins containing tight lenticular sands, which were selected by DOE as priority research targets, have also been pursued as part of this new effort. To date, the following tentative conclusions have been formed: Permeability of the tight gas sands can be as much as three to four orders of magnitude lower than that of conventional gas deposits. Nineteen western geologic basins and trends containing significant volumes of tight gas have been identified. Gas resources in the priority geologic basins have been estimated - Piceance Basin 49 Tcf.; Greater Green River Basin, 136 Tcf.; Uinta Basin, 20 Tcf. Presence of natural micro-fractures within a reservoir and the effective propped length of hydraulically induced fratures are the critical parameters for successful development of tight sand resources. Stimulation technology at the present time is insufficient to efficiently recover gas from lenticular tight reservoirs. 8 figs., 3 tabs.

  1. Slip length measurement of gas flow.

    PubMed

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-16

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas. PMID:27505860

  2. Slip length measurement of gas flow

    NASA Astrophysics Data System (ADS)

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-01

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

  3. Slip length measurement of gas flow.

    PubMed

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-16

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

  4. Retained gas inventory comparison

    SciTech Connect

    BARTON, W.B.

    1999-05-18

    Gas volume data derived from four different analytical methods were collected and analyzed for comparison to volumes originally used in the technical basis for the Basis for Interim Operations (BIO). The original volumes came from Hodgson (1996) listed in the reference section of this document. Hodgson (1996) screened all 177 single and double-shell tanks for the presence of trapped gas in waste via two analytical methods: Surface Level Rise (SLR), and Barometric Pressure Effect (BPE). More recent gas volume projections have been calculated using different analytical techniques along with updates to the parameters used as input to the SLR and BPE models. Gas volumes derived from new analytical instruments include those as measured by the Void Fraction Instrument (VFI) and Retained Gas Sampler (RGS). The results of this comparison demonstrate that the original retained gas volumes of Hodgson (1996) used as a technical basis in developing the BIO were conservative, and were conservative from a safety analysis standpoint. These results represent only comparisons to the original reported volumes using the limited set of newly acquired data that is available.

  5. Gas vesicles.

    PubMed Central

    Walsby, A E

    1994-01-01

    The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins. Images PMID:8177173

  6. Gas magnetometer

    DOEpatents

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2016-05-03

    Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.

  7. Gas separating

    DOEpatents

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  8. Gas separating

    DOEpatents

    Gollan, A.Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  9. The CARIBU gas catcher

    NASA Astrophysics Data System (ADS)

    Savard, G.; Levand, A. F.; Zabransky, B. J.

    2016-06-01

    The CARIBU upgrade of the ATLAS facility provides radioactive beams of neutron-rich isotopes for experiments at low and Coulomb barrier energies. It creates these beam using a large RF gas catcher that collects and cools fission fragments from an intense 252 Cf fission source and transforms them into a low-emittance monoenergetic beam. This beam can then be purified, reaccelerated and delivered to experiments. This technique is fast and universal, providing access to all fission fragment species independently of their chemical properties. The CARIBU gas catcher has been built to operate at high ionization density and in the presence of the contamination from the source. A brief overview of the CARIBU concept is given below, together with a more detailed description of the CARIBU gas catcher and the performance it has now achieved.

  10. Multiplex gas chromatography

    NASA Technical Reports Server (NTRS)

    Valentin, Jose R.

    1990-01-01

    The principles of the multiplex gas chromatography (GC) technique, which is a possible candidate for chemical analysis of planetary atmospheres, are discussed. Particular attention is given to the chemical modulators developed by present investigators for multiplex GC, namely, the thermal-desorption, thermal-decomposition, and catalytic modulators, as well as to mechanical modulators. The basic technique of multiplex GC using chemical modulators and a mechanical modulator is demonstrated. It is shown that, with the chemical modulators, only one gas stream consisting of the carrier in combination with the components is being analyzed, resulting in a simplified instrument that requires relatively few consumables. The mechanical modulator demonstrated a direct application of multiplex GC for the analysis of gases in atmosphere of Titan at very low pressures.

  11. Ambient air contamination: Characterization and detection techniques

    NASA Technical Reports Server (NTRS)

    Nulton, C. P.; Silvus, H. S.

    1985-01-01

    Techniques to characterize and detect sources of ambient air contamination are described. Chemical techniques to identify indoor contaminants are outlined, they include gas chromatography, or colorimetric detection. Organics generated from indoor materials at ambient conditions and upon combustion are characterized. Piezoelectric quartz crystals are used as precision frequency determining elements in electronic oscillators.

  12. Technique of transanal endoscopic microsurgery.

    PubMed

    Buess, G; Kipfmüller, K; Hack, D; Grüssner, R; Heintz, A; Junginger, T

    1988-01-01

    Sessile adenomas are predominantly localized in the rectum and lower sigma. Surgical removal is indicated but often implies an invasive surgical procedure. Using conventional transanal surgical techniques, only the lower rectum can be reached and there are high rates of recurrence. The new technique combines an endoscopic view of the rectum under gas insufflation via a stereoscopic telescope with conventional surgical preparation and suturing. Adenomas can be excised using the mucosectomy technique or full-thickness-excision, whereas carcinomas should be excised using full-thickness excision with a sufficient border of healthy mucosa. In carcinomas of the sacral cavity, we remove the retrorectal fat up to the fascia of Waldeyer, including the regional lymph nodes. Transanal endoscopic microsurgery is the most economical and tissue-saving surgical technique for the removal of rectal adenomas and early rectal carcinomas.

  13. Molecular wake shield gas analyzer

    NASA Technical Reports Server (NTRS)

    Hoffman, J. H.

    1980-01-01

    Techniques for measuring and characterizing the ultrahigh vacuum in the wake of an orbiting spacecraft are studied. A high sensitivity mass spectrometer that contains a double mass analyzer consisting of an open source miniature magnetic sector field neutral gas analyzer and an identical ion analyzer is proposed. These are configured to detect and identify gas and ion species of hydrogen, helium, nitrogen, oxygen, nitric oxide, and carbon dioxide and any other gas or ion species in the 1 to 46 amu mass range. This range covers the normal atmospheric constituents. The sensitivity of the instrument is sufficient to measure ambient gases and ion with a particle density of the order of one per cc. A chemical pump, or getter, is mounted near the entrance aperture of the neutral gas analyzer which integrates the absorption of ambient gases for a selectable period of time for subsequent release and analysis. The sensitivity is realizable for all but rare gases using this technique.

  14. Radon assay and purification techniques

    SciTech Connect

    Simgen, Hardy

    2013-08-08

    Radon is a source of background in many astroparticle physics experiments searching for rare low energy events. In this paper an overview about radon in the field is given including radon detection techniques, radon sources and material screening with respect to radon emanation. Finally, also the problem of long-lived radioactive {sup 222}Rn-daughters and the question of gas purification from radon is addressed.

  15. Use of a portable, automated, open-circuit gas quantification system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions in Holstein cows fed ad libitum or restricted

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sulfur hexafluoride tracer technique (SF**6) is a commonly used method for measuring CH**4 enteric emissions in ruminants. Studies using SF**6 have shown large variation in CH**4 emissions data, inconsistencies in CH**4 emissions across studies, and potential methodological errors. Therefore, th...

  16. Passive gas separator and accumulator device

    DOEpatents

    Choe, H.; Fallas, T.T.

    1994-08-02

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gas-liquid mixture is provided. The cylindrical filter utilizes the principle that surface tension in the pores of the filter prevents gas bubbles from passing through. As a result, the gas collects in the interior region of the filter and coalesces to form larger bubbles in the center of the device. The device is particularly suited for use in microgravity conditions since the swirlers induce a centrifugal force which causes liquid to move from the inner region of the filter, pass the pores, and flow through the outlet of the device while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen which is enclosed by the cylindrical gas separation filter. The screen has pores that are larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the gas separation filter. The device is initially filled with a gas other than that which is to be separated. This technique results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region of the separation device with a ruptured disc which can be ruptured when the device is activated for use. 3 figs.

  17. Well log evaluation of gas hydrate saturations

    USGS Publications Warehouse

    Collett, T.S.

    1998-01-01

    The amount of gas sequestered in gas hydrates is probably enormous, but estimates are highly speculative due to the lack of previous quantitative studies. Gas volumes that may be attributed to a gas hydrate accumulation within a given geologic setting are dependent on a number of reservoir parameters; one of which, gas-hydrate saturation, can be assessed with data obtained from downhole well logging devices. The primary objective of this study was to develop quantitative well-log evaluation techniques which will permit the calculation of gas-hydrate saturations in gas-hydrate-bearing sedimentary units. The "standard" and "quick look" Archie relations (resistivity log data) yielded accurate gas-hydrate and free-gas saturations within all of the gas hydrate accumulations assessed in the field verification phase of the study. Compressional wave acoustic log data have been used along with the Timur, modified Wood, and the Lee weighted average acoustic equations to calculate accurate gas-hydrate saturations in all of the gas hydrate accumulations assessed in this study. The well log derived gas-hydrate saturations calculated in the field verification phase of this study, which range from as low as 2% to as high as 97%, confirm that gas hydrates represent a potentially important source of natural gas.

  18. Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Hansen, Patrick; Whisnant, C. Steven

    2010-02-01

    To prepare frozen-spin HD targets for photonuclear physics at JLab, high purity HD is required. Commercially available gas is only ˜98% HD. To reach the purity required to make nuclear targets, the gas is distilled at low temperature to remove the H2 and D2 impurities. To monitor the distillation process and correlate the gas purity with the spin relaxation times, a low temperature gas chromatograph system has been developed that produces good separation of H2, HD and D2. The system uses a PLOT 5A column in a mixture of LN2 and i-pentane at temperatures between 110K and 135K. With this system, the relative concentrations can be determined with uncertainties of ˜10%. The chromatography process and the resulting chromatograms will be discussed. )

  19. Volcanic Gas

    MedlinePlus

    ... Hazards Tephra/Ash Lava Flows Lahars Volcanic Gas Climate Change Pyroclastic Flows Volcanic Landslides Preparedness Volcano Hazard Zones ... Please see our discussion of volcanic gases and climate change for additional information. Hydrogen sulfide (H 2 S) is ...

  20. Gas Chromatography.

    ERIC Educational Resources Information Center

    Cram, Stuart P.; And Others

    1980-01-01

    Selects fundamental developments in theory, methodology, and instrumentation in gas chromatography (GC). A special section reviews GC in the People's Republic of China. Over 1,000 references are cited. (CS)

  1. Gas Analyzer

    NASA Astrophysics Data System (ADS)

    1989-01-01

    The M200 originated in the 1970's under an Ames Research Center/Stanford University contract to develop a small, lightweight gas analyzer for Viking Landers. Although the unit was not used on the spacecraft, it was further developed by The National Institute for Occupational Safety and Health (NIOSH). Three researchers from the project later formed Microsensor Technology, Inc. (MTI) to commercialize the analyzer. The original version (Micromonitor 500) was introduced in 1982, and the M200 in 1988. The M200, a more advanced version, features dual gas chromatograph which separate a gaseous mixture into components and measure concentrations of each gas. It is useful for monitoring gas leaks, chemical spills, etc. Many analyses are completed in less than 30 seconds, and a wide range of mixtures can be analyzed.

  2. Noncircular orifice holes and advanced fabrication techniques for liquid rocket injectors. Phase 3: Analytical and cold-flow experimental evaluation of rectangular concentric tube injector elements for gas/liquid application. Phase 4: Analytical and experimental evaluation of noncircular injector elements for gas/liquid and liquid/liquid application

    NASA Technical Reports Server (NTRS)

    Mchale, R. M.

    1974-01-01

    Results are presented of a cold-flow and hot-fire experimental study of the mixing and atomization characteristics of injector elements incorporating noncircular orifices. Both liquid/liquid and gas/liquid element types are discussed. Unlike doublet and triplet elements (circular orifices only) were investigated for the liquid/liquid case while concentric tube elements were investigated for the gas/liquid case. It is concluded that noncircular shape can be employed to significant advantage in injector design for liquid rocket engines.

  3. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  4. Modified MBE hardware and techniques and role of gallium purity for attainment of two dimensional electron gas mobility >35×106 cm2/V s in AlGaAs/GaAs quantum wells grown by MBE

    NASA Astrophysics Data System (ADS)

    Gardner, Geoffrey C.; Fallahi, Saeed; Watson, John D.; Manfra, Michael J.

    2016-05-01

    We provide evidence that gallium purity is the primary impediment to attainment of ultra-high mobility in a two-dimensional electron gas (2DEG) in AlGaAs/GaAs heterostructures grown by molecular beam epitaxy (MBE). The purity of gallium can be enhanced dramatically by in-situ high temperature outgassing within an operating MBE. Based on analysis of data from an initial growth campaign in a new MBE system and modifications employed for a 2nd growth campaign, we have produced 2DEGs with low temperature mobility μ in excess of 35×106 cm2/V s at density n=3.0×1011/cm2 and μ=18×106 cm2/V s at n=1.1×1011/cm2. Our 2nd campaign data indicate that gallium purity remains the factor currently limiting μ<40×106 cm2/V s. We describe strategies to overcome this limitation.

  5. Passive gas separator and accumulator device

    DOEpatents

    Choe, Hwang; Fallas, Thomas T.

    1994-01-01

    A separation device employing a gas separation filter and swirler vanes for separating gas from a gasliquid mixture is provided. The cylindrical filter utilizes the principle that surface tension in the pores of the filter prevents gas bubbles from passing through. As a result, the gas collects in the interior region of the filter and coalesces to form larger bubbles in the center of the device. The device is particularly suited for use in microgravity conditions since the swirlers induce a centrifugal force which causes liquid to move from the inner region of the filter, pass the pores, and flow through the outlet of the device while the entrained gas is trapped by the filter. The device includes a cylindrical gas storage screen which is enclosed by the cylindrical gas separation filter. The screen has pores that are larger than those of the filters. The screen prevents larger bubbles that have been formed from reaching and interfering with the pores of the gas separation filter. The device is initially filled with a gas other than that which is to be separated. This technique results in separation of the gas even before gas bubbles are present in the mixture. Initially filling the device with the dissimilar gas and preventing the gas from escaping before operation can be accomplished by sealing the dissimilar gas in the inner region of the separation device with a ruptured disc which can be ruptured when the device is activated for use.

  6. Well log evaluation of gas hydrate saturations

    USGS Publications Warehouse

    Collett, Timothy S.

    1998-01-01

    The amount of gas sequestered in gas hydrates is probably enormous, but estimates are highly speculative due to the lack of previous quantitative studies. Gas volumes that may be attributed to a gas hydrate accumulation within a given geologic setting are dependent on a number of reservoir parameters; one of which, gas-hydrate saturation, can be assessed with data obtained from downhole well logging devices. The primary objective of this study was to develop quantitative well-log evaluation techniques which will permit the calculation of gas-hydrate saturations in gas-hydrate-bearing sedimentary units. The `standard' and `quick look' Archie relations (resistivity log data) yielded accurate gas-hydrate and free-gas saturations within all of the gas hydrate accumulations assessed in the field verification phase of the study. Compressional wave acoustic log data have been used along with the Timur, modified Wood, and the Lee weighted average acoustic equations to calculate accurate gas-hydrate saturations in this study. The well log derived gas-hydrate saturations calculated in the field verification phase of this study, which range from as low as 2% to as high as 97%, confirm that gas hydrates represent a potentially important source of natural gas.

  7. Harmonization of the quantitative determination of volatile fatty acids profile in aqueous matrix samples by direct injection using gas chromatography and high-performance liquid chromatography techniques: Multi-laboratory validation study.

    PubMed

    Raposo, Francisco; Borja, Rafael; Cacho, Jesús A; Mumme, Jan; Mohedano, Ángel F; Battimelli, Audrey; Bolzonella, David; Schuit, Anthony D; Noguerol-Arias, Joan; Frigon, Jean-Claude; Peñuela, Gustavo A; Muehlenberg, Jana; Sambusiti, Cecilia

    2015-09-25

    The performance parameters of volatile fatty acids (VFAs) measurements were assessed for the first time by a multi-laboratory validation study among 13 laboratories. Two chromatographic techniques (GC and HPLC) and two quantification methods such as external and internal standard (ESTD/ISTD) were combined in three different methodologies GC/ESTD, HPLC/ESTD and GC/ISTD. Linearity evaluation of the calibration functions in a wide concentration range (10-1000mg/L) was carried out using different statistical parameters for the goodness of fit. Both chromatographic techniques were considered similarly accurate. The use of GC/ISTD, despite showing similar analytical performance to the other methodologies, can be considered useful for the harmonization of VFAs analytical methodology taking into account the normalization of slope values used for the calculation of VFAs concentrations. Acceptance criteria for VFAs performance parameters of the multi-laboratory validation study should be established as follows: (1) instrument precision (RSDINST≤1.5%); (2) linearity (R(2)≥0.998; RSDSENSITIVITY≤4%; REMAX≤8%; REAVER≤ 3%); (3) precision (RSD≤1.5%); (4) trueness (recovery of 97-103%); (5) LOD (≤3mg/L); and (6) LOQ (10mg/L).

  8. Removal of a sex toy under general anaesthesia using a bimanual-technique and Magill’s forceps: A case report

    PubMed Central

    Obinwa, Obinna; Robertson, Ian; Stokes, Maurice

    2015-01-01

    Introduction Phallic objects may cause large bowel obstruction if not promptly removed. A bi-manual technique with the aid of a Magill’s forceps is presented here. Presentation of case A 68-year-old man presented to the emergency department with severe lower abdominal discomfort, distension and inability to pass urine, flatus or bowel motions. He had inserted a phallic object in the rectum 10 hours prior to presentation and had been unable to remove same. Abdominal examination was remarkable for distension with tenderness also elicited suprapubically and in the left iliac fossa. The foreign body was barely palpable per rectum. Plain radiographs showed prominent left-sided colonic segments. Following the trial of a manual attempt at removal in the emergency department, a decision was made to remove this under anaesthesia due to worsening symptoms. The phallic object was successfully removed under general anaesthesia using bi-manual manipulation assisted by a pair of Magill’s forceps. Discussion The method of removal of phallic objects varies from one individual case to another. In the presence of obstruction, a quick decision must be made for removal under general anaesthesia and the patient will also need to be consented for laparotomy. Previous literature described a “cork-in-bottle” technique using myomectomy screws as well as use of single-incision laparoscopic surgery (SILS) ports for removal of phallic objects. Conclusion Extraction of phallic objects requires ingenuity. We describe another minimally invasive technique of removal that adds to the literature, thereby limiting the need for laparotomy and open removal of foreign bodies. PMID:26322821

  9. Tissue-specific metabolite profiling of Cyperus rotundus L. rhizomes and (+)-nootkatone quantitation by laser microdissection, ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and gas chromatography-mass spectrometry techniques.

    PubMed

    Jaiswal, Yogini; Liang, Zhitao; Guo, Ping; Ho, Hing-Man; Chen, Hubiao; Zhao, Zhongzhen

    2014-07-23

    Cyperus rotundus L. is a plant species commonly found in both India and China. The caused destruction of this plant is of critical concern for agricultural produce. Nevertheless, it can serve as a potential source of the commercially important sesquiterpenoid (+)-nootkatone. The present work describes comparative metabolite profiling and (+)-nootkatone content determination in rhizome samples collected from these two countries. Laser dissected tissues, namely, the cortex, hypodermal fiber bundles, endodermis, amphivasal vascular bundles, and whole rhizomes were analyzed by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). Gas chromatography-mass spectrometry (GC-MS) analysis was used for profiling of essential oil constituents and quantitation of (+)-nootkatone. The content of (+)-nootkatone was found to be higher in samples from India (30.47 μg/10 g) compared to samples from China (21.72 μg/10 g). The method was validated as per International Conference on Harmonisation (ICH) guidelines (Q2 R1). The results from this study can be applied for quality control and efficient utilization of this terpenoid-rich plant for several applications in food-based industries. PMID:24938835

  10. Line gas sampling system ensures accurate analysis

    SciTech Connect

    Not Available

    1992-06-01

    Tremendous changes in the natural gas business have resulted in new approaches to the way natural gas is measured. Electronic flow measurement has altered the business forever, with developments in instrumentation and a new sensitivity to the importance of proper natural gas sampling techniques. This paper reports that YZ Industries Inc., Snyder, Texas, combined its 40 years of sampling experience with the latest in microprocessor-based technology to develop the KynaPak 2000 series, the first on-line natural gas sampling system that is both compact and extremely accurate. This means the composition of the sampled gas must be representative of the whole and related to flow. If so, relative measurement and sampling techniques are married, gas volumes are accurately accounted for and adjustments to composition can be made.

  11. Experimental Techniques for Thermodynamic Measurements of Ceramics

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Putnam, Robert L.; Navrotsky, Alexandra

    1999-01-01

    Experimental techniques for thermodynamic measurements on ceramic materials are reviewed. For total molar quantities, calorimetry is used. Total enthalpies are determined with combustion calorimetry or solution calorimetry. Heat capacities and entropies are determined with drop calorimetry, differential thermal methods, and adiabatic calorimetry . Three major techniques for determining partial molar quantities are discussed. These are gas equilibration techniques, Knudsen cell methods, and electrochemical techniques. Throughout this report, issues unique to ceramics are emphasized. Ceramic materials encompass a wide range of stabilities and this must be considered. In general data at high temperatures is required and the need for inert container materials presents a particular challenge.

  12. Finding and Producing Oil and Gas

    ERIC Educational Resources Information Center

    Geotimes, 1974

    1974-01-01

    Condenses the current research in exploration for gas and oil as described at a symposium at Case Western Reserve University. Briefly discusses reserves, oil exploration and extraction techniques. (BR)

  13. Prosthetic mesh "slim-cigarette like" for laparoscopic repair of ventral hernias: a new technique without transabdominal fixation sutures.

    PubMed

    Canton, S A; Merigliano, S; Pasquali, C

    2016-06-01

    Prosthetic mesh rolled up and fixed with stitches like a slim cigarette ("slim-mesh") for laparoscopic ventral hernia (VH) repair is an new technique which allows an easy intraperitoneally introduction, distension and circumferential fixation of a prosthetic mesh without transabdominal fixation sutures even for meshes larger than 16 cm up to 30 cm for the "slim-mesh" repair of wide ventral hernias. We report the technique of laparoscopic repair of VH with "slim-mesh". This technique enables an easy intra-peritoneally introduction of the mesh through the trocar because it reduces consistently its size, it allows a rapid intra-abdominal handling of the mesh and a fast and easy fixation for VH repair. The average time of surgery with "slim-mesh" for treatment of all 28 VH was 97 min ranging from 57 to 160 min. The average time for the repair of the 24 VH smaller than 10 cm was 91 and 135 min for the four VH larger than 10-22 cm. This new surgical technique leads to a reduction of surgical risks avoiding the use of transfascial sutures with the associated complications. This new surgical procedure in our experience is fast, safe, simple and also easily reproducible by surgeons in laparoscopic training. This technique may be used in wide VH (larger than 10-22 cm) that generally require open surgery.

  14. Gas sensor

    DOEpatents

    Schmid, Andreas K.; Mascaraque, Arantzazu; Santos, Benito; de la Figuera, Juan

    2014-09-09

    A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.

  15. Laser and gas centrifuge enrichment

    NASA Astrophysics Data System (ADS)

    Heinonen, Olli

    2014-05-01

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  16. Laser and gas centrifuge enrichment

    SciTech Connect

    Heinonen, Olli

    2014-05-09

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  17. Gas-influx detection with MWD technology

    SciTech Connect

    Bryant, T.M.; Grosso, D.S.; Wallace, S.N. )

    1991-12-01

    This paper describes a new gas-influx detection technique that monitors the acoustic responses of annular measurement-while-drilling (MWD) pulses to provide a rapid, early warning of the development of potential gas-kick situations. The technique has been evaluated in both water- and oil-based muds during about 40 gas-kick simulations at two full-scale testing facilities. Free gas is identified by amplitude attenuation and phase delay of MWD fundamentals and their harmonic frequencies. Detection is independent of influx location because the entire length of the annulus between the bit nozzles and a surface-pressure transducer is sampled. Detection of potential gas-kick situations generally occurred within minutes of influx initiation, before any significant gas expansion. Some tests also evaluated a downhole MWD mud-resistivity sensor. Results indicated that both these techniques, and particularly the pulse acoustics, can provide unequivocal confirmation of gas and an earlier warning of gas-kick situations than conventional kick- detection techniques.

  18. Isolation and recovery of selected polybrominated diphenyl ethers from human serum and sheep serum: coupling reversed-phase solid-phase disk extraction and liquid-liquid extraction techniques with a capillary gas chromatographic electron capture negative ion mass spectrometric determinative technique.

    PubMed

    Loconto, Paul R; Isenga, David; O'Keefe, Michael; Knottnerus, Mark

    2008-01-01

    Polybrominated diphenyl ethers (PBDEs) are isolated and recovered with acceptable percent recoveries from human serum via liquid-liquid extraction and column chromatographic cleanup and fractionation with quantitation using capillary gas chromatography-mass spectrometry with electron capture negative ion and selected ion monitoring. PBDEs are found in unspiked serum. An alternative sample preparation approach is developed using sheep serum that utilizes a formic acid pre-treatment followed by reversed-phase solid-phase disk extraction and normal-phase solid-phase cleanup using acidified silica gel that yields>50% recoveries. When these percent recoveries are combined with a minimized phase ratio for human serum and very low instrument detection limits, method detection limits below 500 parts-per-trillion are realized.

  19. A solid phase microextraction coating based on ionic liquid sol-gel technique for determination of benzene, toluene, ethylbenzene and o-xylene in water samples using gas chromatography flame ionization detector.

    PubMed

    Sarafraz-Yazdi, Ali; Vatani, Hossein

    2013-07-26

    Ionic liquid mediated sol-gel sorbents for head-space solid phase microextraction (HS-SPME) were developed for the extraction of benzene, toluene, ethylbenzene and o-xylene (BTEX) compounds from water samples in ultra-trace levels. The analytes were subsequently analyzed with gas chromatography coupled to flame ionization detector (GC-FID). Three different coating fibers were prepared including: poly(dimethylsiloxane) (PDMS), coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a higher temperature than decomposition temperature of ionic liquid (PDMS-IL-HT) and coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a lower temperature than decomposition temperature of ionic liquid (PDMS-IL-LT). Prepared fibers demonstrate many advantages such as high thermal and chemical stabilities due to the chemical bonding of the coatings with the silanol groups on the fused-silica surface fiber. These fibers have shown long life time up to 180 extractions. The scanning electron micrographs of the fibers surfaces revealed that addition of ionic liquid into the sol solution during the sol-gel process increases the fiber coating thickness, affects the form of fiber structure and also leaves high pores in the fiber surface that cause high surface area and therefore increases sample capacity of the fibers. The important parameters that affect the extraction efficiency are desorption temperature and time, sample volume, extraction temperature, extraction time, stirring speed and salt effect. Therefore these factors were investigated and optimized. Under optimal conditions, the dynamic linear range with PDMS-IL-HT, PDMS and PDMS-IL-LT fibers were 0.3-200,000; 50-200,000 and 170-150,000pgmL(-1) and the detection limits (S/N=3) were 0.1-2 and 15-200 and 50-500pgmL(-1), and limit of quantifications (S/N=10) were 0.3-8 and 50-700 and 170-1800, respectively. The relative

  20. GAS SEAL

    DOEpatents

    Monson, H.; Hutter, E.

    1961-07-11

    A seal is described for a cover closing an opening in the top of a pressure vessel that may house a nuclear reactor. The seal comprises a U-shaped trough formed on the pressure vessel around the opening therein, a mass of metal in the trough, and an edge flange on the cover extending loosely into the trough and dipping into the metal mass. The lower portion of the metal mass is kept melted, and the upper portion, solid. The solid pontion of the metal mass prevents pressure surges in the vessel from expelling the liquid portion of the metal mass from the trough; the liquld portion, thus held in place by the solid portion, does not allow gas to go through, and so gas cannot escape through shrinkage holes in the solid portion.

  1. Volcanic gas

    USGS Publications Warehouse

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  2. Food consumption and digestion time estimation of spotted scat, Scatophagus argus, using X-radiography technique

    NASA Astrophysics Data System (ADS)

    Hashim, Marina; Abidin, Diana Atiqah Zainal; Das, Simon K.; Ghaffar, Mazlan Abd.

    2014-09-01

    The present study was conducted to investigate the food consumption pattern and gastric emptying time using x-radiography technique in scats fish, Scatophagus argus feeding to satiation in laboratory conditions. Prior to feeding experiment, fish of various sizes were examined their stomach volume, using freshly prepared stomachs ligatured at the tips of the burret, where the maximum amount of distilled water collected in the stomach were measured (ml). Stomach volume is correlated with maximum food intake (Smax) and it can estimate the maximum stomach distension by allometric model i.e volume=0.0000089W2.93. Gastric emptying time was estimated using a qualitative X-radiography technique, where the fish of various sizes were fed to satiation at different time since feeding. All the experimental fish was feed into satiation using radio-opaque barium sulphate (BaSO4) paste injected in the wet shrimp in proportion to the body weight. The BaSO4 was found suitable to track the movement of feed/prey in the stomach over time and gastric emptying time of scats fish can be estimated. The results of qualitative X-Radiography observation of gastric motility, showed the fish (200 gm) that fed to maximum satiation meal (circa 11 gm) completely emptied their stomach within 30 - 36 hrs. The results of the present study will provide the first baseline information on the stomach volume, gastric emptying of scats fish in captivity.

  3. Food consumption and digestion time estimation of spotted scat, Scatophagus argus, using X-radiography technique

    SciTech Connect

    Hashim, Marina; Abidin, Diana Atiqah Zainal; Das, Simon K.; Ghaffar, Mazlan Abd.

    2014-09-03

    The present study was conducted to investigate the food consumption pattern and gastric emptying time using x-radiography technique in scats fish, Scatophagus argus feeding to satiation in laboratory conditions. Prior to feeding experiment, fish of various sizes were examined their stomach volume, using freshly prepared stomachs ligatured at the tips of the burret, where the maximum amount of distilled water collected in the stomach were measured (ml). Stomach volume is correlated with maximum food intake (S{sub max}) and it can estimate the maximum stomach distension by allometric model i.e volume=0.0000089W{sup 2.93}. Gastric emptying time was estimated using a qualitative X-radiography technique, where the fish of various sizes were fed to satiation at different time since feeding. All the experimental fish was feed into satiation using radio-opaque barium sulphate (BaSO{sub 4}) paste injected in the wet shrimp in proportion to the body weight. The BaSO{sub 4} was found suitable to track the movement of feed/prey in the stomach over time and gastric emptying time of scats fish can be estimated. The results of qualitative X-Radiography observation of gastric motility, showed the fish (200 gm) that fed to maximum satiation meal (circa 11 gm) completely emptied their stomach within 30 - 36 hrs. The results of the present study will provide the first baseline information on the stomach volume, gastric emptying of scats fish in captivity.

  4. Technique of Functional and Motility Test: How to Perform Biofeedback for Constipation and Fecal Incontinence

    PubMed Central

    Lee, Hyo Jeong; Jung, Kee Wook

    2013-01-01

    Biofeedback therapy is an instrument-based learning process centered on operant conditioning. The goal of biofeedback therapy in defecatory disorders is to strengthen the pelvic floor muscles, retrain rectal sensation and coordinate pelvic floor muscles during evacuation. Biofeedback therapy, in a broader sense, includes education, counseling, and diaphragmatic muscle training as well as exercise, sensory, and coordination training. For dyssynergic defecation, biofeedback therapy is a well-known and useful treatment option that had response rates of approximately 70-80% in randomized controlled trials. Biofeedback therapy for dyssynergic defecation consists of improving the abdominal push effort together with biofeedback technique-guided pelvic floor relaxation followed by simulated defecation and/or sensory training. For fecal incontinence, the results of a randomized controlled trial, which had a response rate of 76%, indicated that biofeedback therapy is useful in selected patients who fail to respond to conservative treatment and that training to enhance rectal discrimination of sensation may be helpful in reducing fecal incontinence. The focus of biofeedback therapy for fecal incontinence is on exercising external sphincter contractions under instant feedback, either alone or synchronously with rectal distension and/or sensory training. Biofeedback therapy is a safe treatment that may produce durable improvement beyond the active treatment period; however, a well-designed study to establish a standard protocol for biofeedback therapy is needed. This review discusses the technique of biofeedback therapy to achieve the goal and clinical outcomes for constipation and fecal incontinence. PMID:24199015

  5. Technique of functional and motility test: how to perform biofeedback for constipation and fecal incontinence.

    PubMed

    Lee, Hyo Jeong; Jung, Kee Wook; Myung, Seung-Jae

    2013-10-01

    Biofeedback therapy is an instrument-based learning process centered on operant conditioning. The goal of biofeedback therapy in defecatory disorders is to strengthen the pelvic floor muscles, retrain rectal sensation and coordinate pelvic floor muscles during evacuation. Biofeedback therapy, in a broader sense, includes education, counseling, and diaphragmatic muscle training as well as exercise, sensory, and coordination training. For dyssynergic defecation, biofeedback therapy is a well-known and useful treatment option that had response rates of approximately 70-80% in randomized controlled trials. Biofeedback therapy for dyssynergic defecation consists of improving the abdominal push effort together with biofeedback technique-guided pelvic floor relaxation followed by simulated defecation and/or sensory training. For fecal incontinence, the results of a randomized controlled trial, which had a response rate of 76%, indicated that biofeedback therapy is useful in selected patients who fail to respond to conservative treatment and that training to enhance rectal discrimination of sensation may be helpful in reducing fecal incontinence. The focus of biofeedback therapy for fecal incontinence is on exercising external sphincter contractions under instant feedback, either alone or synchronously with rectal distension and/or sensory training. Biofeedback therapy is a safe treatment that may produce durable improvement beyond the active treatment period; however, a well-designed study to establish a standard protocol for biofeedback therapy is needed. This review discusses the technique of biofeedback therapy to achieve the goal and clinical outcomes for constipation and fecal incontinence.

  6. Measurements of 222Rn, 220Rn, and CO2 Emissions in Natural CO2 Fields in Wyoming: MVA Techniques for Determining Gas Transport and Caprock Integrity

    SciTech Connect

    Kaszuba, John; Sims, Kenneth

    2014-09-30

    An integrated field-laboratory program evaluated the use of radon and CO2 flux measurements to constrain source and timescale of CO2 fluxes in environments proximate to CO2 storage reservoirs. By understanding the type and depth of the gas source, the integrity of a CO2 storage reservoir can be assessed and monitored. The concept is based on correlations of radon and CO2 fluxes observed in volcanic systems. This fundamental research is designed to advance the science of Monitoring, Verification, and Accounting (MVA) and to address the Carbon Storage Program goal of developing and validating technologies to ensure 99 percent storage performance. Graduate and undergraduate students conducted the research under the guidance of the Principal Investigators; in doing so they were provided with training opportunities in skills required for implementing and deploying CCS technologies. Although a final method or “tool” was not developed, significant progress was made. The field program identified issues with measuring radon in environments rich in CO2. Laboratory experiments determined a correction factor to apply to radon measurements made in CO2-bearing environments. The field program also identified issues with radon and CO2-flux measurements in soil gases at a natural CO2 analog. A systematic survey of radon and CO2 flux in soil gases at the LaBarge CO2 Field in Southwest Wyoming indicates that measurements of 222Rn (radon), 220Rn (thoron), and CO2 flux may not be a robust method for monitoring the integrity of a CO2 storage reservoir. The field program was also not able to correlate radon and CO2 flux in the CO2-charged springs of the Thermopolis hydrothermal system. However, this part of the program helped to motivate the aforementioned laboratory experiments that determined

  7. Gas reburning technologies

    SciTech Connect

    Booth, M.

    1996-11-01

    Natural gas reburning technologies are outlined. The following topics are discussed: the reburning process, EER gas reburning experience, gas reburning NOx control overview, Hennepin (tangential) long term test, second generation gas reburning, integrating gas reburning and SNCR, advanced gas reburning process, second generation advanced reburning improvements, and second generation advanced reburning configurations.

  8. Reciprocity theory of gas surface interactions

    NASA Astrophysics Data System (ADS)

    Agbormbai, Adolf A.

    1989-11-01

    Since the Direct Simulation Monte Carlo (DSMC) method has established itself as a standard technique for numerically computing rarefied gas flows, it follows that to develop the theory of rarefied gas dynamics a framework for its fundamental microscopic processes needs to be formulated, i.e., intermolecular collisions and gas surface interactions, which lead to rigorous statistical models that can be utilized in the code. In this report attention is focussed on the mechanism of gas surface interactions. A reciprocity theory for it, which leads to models that can be utilized in the DSMC code, is formulated.

  9. Determination of gas volume trapped in a closed fluid system

    NASA Technical Reports Server (NTRS)

    Hunter, W. F.; Jolley, J. E.

    1971-01-01

    Technique involves extracting known volume of fluid and measuring system before and after extraction, volume of entrapped gas is then computed. Formula derived from ideal gas laws is basis of this method. Technique is applicable to thermodynamic cycles and hydraulic systems.

  10. Asymmetric membranes for gas separations

    SciTech Connect

    Finken, H.

    1985-01-01

    Recent membrane developments for gaseous mixture separations are compared to the development of reverse osmosis membranes for water desalination. The goals of these developments have been the search for ideal permselective polymeric materials, techniques for producing ultrathin membrane layers free of imperfections and transforming gelled reverse osmosis membranes into solid gas permeation membranes. A novel approach to meeting the basic requirements of high permselectivity is attempted by altering the physical polymer structure within the membrane prior to application for gas separation. The influence of these physical interactions on membrane properties is presented. 47 references, 11 figures, 6 tables.

  11. Review of air flow measurement techniques

    SciTech Connect

    McWilliams, Jennifer

    2002-12-01

    Airflow measurement techniques are necessary to determine the most basic of indoor air quality questions: ''Is there enough fresh air to provide a healthy environment for the occupants of the building?'' This paper outlines airflow measurement techniques, but it does not make recommendations for techniques that should be used. The airflows that will be discussed are those within a room or zone, those between rooms or zones, such as through doorways (open or closed) or passive vents, those between the building and outdoors, and those through mechanical air distribution systems. Techniques that are highlighted include particle streak velocimetry, hot wire anemometry, fan pressurization (measuring flow at a given pressure), tracer gas, acoustic methods for leak size determination, the Delta Q test to determine duct leakage flows, and flow hood measurements. Because tracer gas techniques are widely used to measure airflow, this topic is broken down into sections as follows: decay, pulse injection, constant injection, constant concentration, passive sampling, and single and multiple gas measurements for multiple zones.

  12. Fuel gas conditioning process

    DOEpatents

    Lokhandwala, Kaaeid A.

    2000-01-01

    A process for conditioning natural gas containing C.sub.3+ hydrocarbons and/or acid gas, so that it can be used as combustion fuel to run gas-powered equipment, including compressors, in the gas field or the gas processing plant. Compared with prior art processes, the invention creates lesser quantities of low-pressure gas per unit volume of fuel gas produced. Optionally, the process can also produce an NGL product.

  13. Genesis Noble Gas Measurements

    NASA Technical Reports Server (NTRS)

    Hohenberg, Charles M.

    2005-01-01

    The original thrust of our Genesis funding was to extend and refine the noble gas analytical capabilities of this laboratory to improve the precision and accuracy of noble gas measurements in order to optimize the scientific return from the Genesis Mission. This process involved both instrumental improvement (supplemented by a SRLIDAP instrument grant) and refinement of technique. The Genesis landing mishap shifted our emphasis to the irregular aluminum heat shield material from the flat collector wafers. This has required redesign of our laser extraction cells to accommodate the longer focal lengths required for laser extraction from non-flat surfaces. Extraction of noble gases from solid aluminum surfaces, rather than thin coatings on transparent substrates has required refinement of controlled-depth laser ablation techniques. Both of these bring new problems, both with potentially higher blanks form larger laser cells and the larger quantities of evaporated aluminum which can coat the sapphire entrance ports. This is mainly a problem for the heavy noble gases where larger extraction areas are required, necessitating the new aluminum vapor containment techniques described below. With the Genesis Mission came three new multiple multiplier noble gas mass spectrometers to this laboratory, one built solely by us (Supergnome-M), one built in collaboration with Nu-Instruments (Noblesse), and one built in collaboration with GVI (Helix). All of these have multiple multiplier detection sections with the Nu-Instruments using a pair of electrostatic quad lenses for isotope spacing and the other two using mechanically adjustable positions for the electron multipliers. The Supergnome-M and Noblesse are installed and running. The GVI instrument was delivered a year late (in March 2005) and is yet to be installed by GVI. As with all new instruments there were some initial development issues, some of which are still outstanding. The most serious of these are performance issues

  14. The Noble Gas Fingerprint in a UK Unconventional Gas Reservoir

    NASA Astrophysics Data System (ADS)

    McKavney, Rory; Gilfillan, Stuart; Györe, Domokos; Stuart, Fin

    2016-04-01

    In the last decade, there has been an unprecedented expansion in the development of unconventional hydrocarbon resources. Concerns have arisen about the effect of this new industry on groundwater quality, particularly focussing on hydraulic fracturing, the technique used to increase the permeability of the targeted tight shale formations. Methane contamination of groundwater has been documented in areas of gas production1 but conclusively linking this to fugitive emissions from unconventional hydrocarbon production has been controversial2. A lack of baseline measurements taken before drilling, and the equivocal interpretation of geochemical data hamper the determination of possible contamination. Common techniques for "fingerprinting" gas from discrete sources rely on gas composition and isotopic ratios of elements within hydrocarbons (e.g. δ13CCH4), but the original signatures can be masked by biological and gas transport processes. The noble gases (He, Ne, Ar, Kr, Xe) are inert and controlled only by their physical properties. They exist in trace quantities in natural gases and are sourced from 3 isotopically distinct environments (atmosphere, crust and mantle)3. They are decoupled from the biosphere, and provide a separate toolbox to investigate the numerous sources and migration pathways of natural gases, and have found recent utility in the CCS4 and unconventional gas5 industries. Here we present a brief overview of noble gas data obtained from a new coal bed methane (CBM) field, Central Scotland. We show that the high concentration of helium is an ideal fingerprint for tracing fugitive gas migration to a shallow groundwater. The wells show variation in the noble gas signatures that can be attributed to differences in formation water pumping from the coal seams as the field has been explored for future commercial development. Dewatering the seams alters the gas/water ratio and the degree to which noble gases degas from the formation water. Additionally the

  15. Gas lift systems make ideal offshore workers

    SciTech Connect

    1999-05-01

    With a low initial installation cost and small footprint, gas lift systems are well suited for offshore installations where compressed gas is usually already available. These systems are used on multiple and slimhole completions and handle sandy conditions well. They are also used to kick off wells that will flow naturally once the heavier completion fluids leave the production string. Gas lift itself is a mature workaday technology. Measurement and control of gas flow is an area of intense development in gas lift technology. One new control method involves production of multiple completions through a single wellbore. Typically, gas lift valves are opened and closed through tubing pressure. But downhole measurement technology does not yet yield information good enough for stable gas lift control of multiple completions. Gas lift is proving to be a useful AL technique in conjunction with electric submersible pumps (ESP). Located above the ESP pump, the gas lift can reduce the head and allow greater flow. This is helpful when small casing restricts the size of the downhole ESP pump. Wells can usually be produced by the gas lift alone in case of ESP failure, or by replacing the ESP where schedules, high repair costs or low prices rule out repair.

  16. TEA laser gas mixture optimization

    NASA Astrophysics Data System (ADS)

    Lipchak, W. Michael; Luck, Clarence F.

    1982-11-01

    The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO2 TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.

  17. TEA laser gas mixture optimization

    SciTech Connect

    Lipchak, W.M.; Luck, C.F.

    1982-11-01

    The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO/sub 2/ TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.

  18. Oil and Gas Exploration Planning using VOI Technique

    NASA Astrophysics Data System (ADS)

    Peskova, D. N.; Sizykh, A. V.; Rukavishnikov, V. S.

    2016-03-01

    Paper deals with actual problem about making decisions during field development. The main aim was to apply method “Value of information” in order to estimate the necessity of field exploration works and show the effectiveness of this method. The object of analysis - field X, which is located in the Eastern Siberia. The reservoir is B13 formation of Vend age. The Field has complex structure, and divided into blocks by faults. During evaluation of the project, main uncertainties and oil in place were obtained for three blocks of the field. According to uncertainty analysis, it was suggested to drill a new exploration well, and value of information method was applied to estimate results from this exploration works. Economic evaluation of the value of information method was made by choosing optimal development strategy. According to the obtained results, drilling of the exploration wells for blocks 1 and 3 of the field X is a good decision, while drilling a well in the second block is risky and not recommended. Also using the value of information, optimal well locations were advised - well l_le for the first block, and well 33 for the third block.

  19. Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Qian, Michael C.

    Gas chromatography (GC) has many applications in the analysis of food products. GC has been used for the determination of fatty acids, triglycerides, cholesterol, gases, water, alcohols, pesticides, flavor compounds, and many more. While GC has been used for other food components such as sugars, oligosaccharides, amino acids, peptides, and vitamins, these substances are more suited to analysis by high performance liquid chromatography. GC is ideally suited to the analysis of volatile substances that are thermally stable. Substances such as pesticides and flavor compounds that meet these criteria can be isolated from a food and directly injected into the GC. For compounds that are thermally unstable, too low in volatility, or yield poor chromatographic separation due to polarity, a derivatization step must be done before GC analysis. The two parts of the experiment described here include the analysis of alcohols that requires no derivatization step, and the analysis of fatty acids which requires derivatization. The experiments specify the use of capillary columns, but the first experiment includes conditions for a packed column.

  20. The radiocarbon hydroxyl technique

    NASA Technical Reports Server (NTRS)

    Campbell, Malcolm J.; Sheppard, John C.

    1994-01-01

    The Radiocarbon Technique depends upon measuring the rate of oxidation of CO in an essentially unperturbed sample of air. The airborne technique is slightly different. Hydroxyl concentrations can be calculated directly; peroxyl concentrations can be obtained by NO doping.