New insights into the molecular mechanism of intestinal fatty acid absorption

PubMed Central

Wang, Tony Y.; Liu, Min; Portincasa, Piero; Wang, David Q.-H.

2013-01-01

Background Dietary fat is the most important energy source of all the nutrients. Fatty acids, stored as triacylglycerols in the body, are an important reservoir of stored energy and derive primarily from animal fats and vegetable oils. Design Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, i.e., fatty acid transporters on the apical membrane of enterocytes. Results These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical-chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. Conclusions A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide. PMID:24102389

Ursodeoxycholic and deoxycholic acids: A good and a bad bile acid for intestinal calcium absorption.

PubMed

Rodríguez, Valeria; Rivoira, María; Marchionatti, Ana; Pérez, Adriana; Tolosa de Talamoni, Nori

2013-12-01

The aim of this study was to investigate the effect of ursodeoxycholic acid (UDCA) on intestinal Ca(2+) absorption and to find out whether the inhibition of this process caused by NaDOC could be prevented by UDCA. Chicks were employed and divided into four groups: (a) controls, (b) treated with 10mM NaDOC, (c) treated with 60 μg UDCA/100g of b.w., and (d) treated with 10mM NaDOC and 60 μg UDCA/100g of b.w. UDCA enhanced intestinal Ca(2+) absorption, which was time and dose-dependent. UDCA avoided the inhibition of intestinal Ca(2+) absorption caused by NaDOC. Both bile acids altered protein and gene expression of molecules involved in the transcellular pathway of intestinal Ca(2+) absorption, but in the opposite way. UDCA aborted the oxidative stress produced by NaDOC in the intestine. UDCA and UDCA plus NaDOC increased vitamin D receptor protein expression. In conclusion, UDCA is a beneficial bile acid for intestinal Ca(2+) absorption. Contrarily, NaDOC inhibits the intestinal cation absorption through triggering oxidative stress. The use of UDCA in patients with cholestasis would be benefited because of the protective effect on the intestinal Ca(2+) absorption, avoiding the inhibition caused by hydrophobic bile acids and neutralizing the oxidative stress. Copyright © 2013 Elsevier Inc. All rights reserved.

New insights into the molecular mechanism of intestinal fatty acid absorption.

PubMed

Wang, Tony Y; Liu, Min; Portincasa, Piero; Wang, David Q-H

2013-11-01

Dietary fat is one of the most important energy sources of all the nutrients. Fatty acids, stored as triacylglycerols (also called triglycerides) in the body, are an important reservoir of stored energy and derived primarily from animal fats and vegetable oils. Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, that is, fatty acid transporters on the apical membrane of enterocytes. These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide. © 2013 Stichting European Society for Clinical Investigation Journal Foundation. Published by John Wiley & Sons Ltd.

The gas-phase absorption spectrum of a neutral GFP model chromophore.

PubMed

Lammich, L; Petersen, M Axman; Nielsen, M Brøndsted; Andersen, L H

2007-01-01

We have studied the gas-phase absorption properties of the green fluorescent protein (GFP) chromophore in its neutral (protonated) charge state in a heavy-ion storage ring. To accomplish this we synthesized a new molecular chromophore with a charged NH(3) group attached to a neutral model chromophore of GFP. The gas-phase absorption cross section of this chromophore molecule as a function of the wavelength is compared to the well-known absorption profile of GFP. The chromophore has a maximum absorption at 415 +/- 5 nm. When corrected for the presence of the charged group attached to the GFP model chromophore, the unperturbed neutral chromophore is predicted to have an absorption maximum at 399 nm in vacuum. This is very close to the corresponding absorption peak of the protein at 397 nm. Together with previous data obtained with an anionic GFP model chromophore, the present data show that the absorption of GFP is primarily determined by intrinsic chromophore properties. In other words, there is strong experimental evidence that, in terms of absorption, the conditions in the hydrophobic interior of this protein are very close to those in vacuum.

[Removal of CO2 from simulated flue gas of power plants by membrane-based gas absorption processes].

PubMed

Yang, Ming-Fen; Fang, Meng-Xiang; Zhang, Wei-Feng; Wang, Shu-Yuan; Xu, Zhi-Kang; Luo, Zhong-Yang; Cen, Ke-Fa

2005-07-01

Three typical absorbents such as aqueous of aminoacetic acid potassium (AAAP), monoethanolamine (MEA) and methyldiethanolamine(MDEA) are selected to investigate the performance of CO2 separation from flue gas via membrane contactors made of hydrophobic hollow fiber polypropylene porous membrane. Impacts of absorbents, concentrations and flow rates of feeding gas and absorbent solution, cyclic loading of CO2 on the removal rate and the mass transfer velocity of CO2 are discussed. The results demonstrate that the mass transfer velocity was 7.1 mol x (m2 x s)(-1) for 1 mol x L(-1) MEA with flow rate of 0.1 m x s(-1) and flue gas with that of 0.211 m x s(-1). For 1 mol L(-1) AAAP with flow rate of 0.05 m x s(-1) and flue gas of 0.211 m x s(-1), CO2 removal rate (eta) was 93.2 % and eta was 98% for 4 mol x L(-1) AAAP under the same conditions. AAAP being absorbent, eta was higher than 90% in a wider range of concentrations of CO2. It indicates that membrane-based absorption process is a widely-applied and promising way of CO2 removal from flue gas of power plants, which not only appropriates for CO2 removal of flue gas of widely-used PF and NGCC, but also for that of flue gas of IGCC can be utilized widely in future.

Utilization of red mud and bagasse for production of gas absorption materials

NASA Astrophysics Data System (ADS)

Thang, Nguyen Hoc; Quyen, Pham Vo Thi Ha; Nhung, Le Thuy; Phong, Dang Thanh; Tuyen, Nguyen Ngoc Kim

2018-04-01

Gas treatment or/and gas absorption is field which has more investigation from researchers. They are finding optimal solutions from catalyst or synthesized materials to obtain the best benefit for factories and community. This study would like to introduce a method to synthesis the gas absorption materials responding requirements for the process of gas treatment. More specially, raw materials used to produce the materials are industrial waste impacting negatively on the environment. In which, red mud is solid waste of Bayer process from bauxite mining which is being the hard problem to have solutions for its management and utilization, and bagasse is industrial waste of sugar factories. Both red mud and bagasse were dried, ground, and sieved and then mixed with bentonite and water for forming by wet pressing method. Continuously, the mixtures were passed processes of heat treatment at 400°C. The final samples were tested physic-chemical properties and characterized for microstructure. The productions were also tested for gas absorption capacity with data obtained very positive in comparison with others.

Ultraviolet gas absorption and dust extinction toward M8

NASA Technical Reports Server (NTRS)

Boggs, Don; Bohm-Vitense, Erika

1990-01-01

Interstellar absorption lines are analyzed using high-resolution IUE spectra of 11 stars in the young cluster NGC 6530 located in the M8 region. High-velocity clouds at -35 km/s and -60 km/s are seen toward all cluster stars. The components arise in gases that are part of large interstellar bubbles centered on the cluster and driven by stellar winds of the most luminous members. Absorption lines of species of different ionization states are separated in velocity. The velocity stratification is best explained as a 'champagne' flow of ionized gas away from the cluster. The C IV/Si IV ratios toward the hotter cluster members are consistent with simple photoionization models if the gas-phase C/Si ratio is increased by preferential accretion onto dust grains. High ion column densities in the central cluster decline with distance from W93, suggesting that radiation from a hot source near W93 has photoionized gas in the central cluster.

Measurement of water absorption capacity in wheat flour by a headspace gas chromatographic technique.

PubMed

Xie, Wei-Qi; Yu, Kong-Xian; Gong, Yi-Xian

2018-04-17

The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiant energy absorption studies for laser propulsion. [gas dynamics

NASA Technical Reports Server (NTRS)

Caledonia, G. E.; Wu, P. K. S.; Pirri, A. N.

1975-01-01

A study of the energy absorption mechanisms and fluid dynamic considerations for efficient conversion of high power laser radiation into a high velocity flow is presented. The objectives of the study are: (1) to determine the most effective absorption mechanisms for converting laser radiation into translational energy, and (2) to examine the requirements for transfer of the absorbed energy into a steady flow which is stable to disturbances in the absorption zone. A review of inverse Bremsstrahlung, molecular and particulate absorption mechanisms is considered and the steady flow and stability considerations for conversion of the laser power to a high velocity flow in a nozzle configuration is calculated. A quasi-one-dimensional flow through a nozzle was formulated under the assumptions of perfect gas.

Energy absorption is reduced with oleic acid supplements in human short bowel syndrome.

PubMed

Compher, Charlene W; Kinosian, Bruce P; Rubesin, Stephen E; Ratcliffe, Sarah J; Metz, David C

2009-01-01

Oleic acid premeal supplements have been described as a method to trigger the ileal brake and thus lengthen transit time and the opportunity for nutrient absorption. The aims of this study were to determine whether oleic acid supplements would lengthen transit time and improve absorption of nutrients in study participants with short bowel syndrome as well as affect diarrhea or patient weight. A double-blind, controlled, random-order crossover trial was conducted in 8 study participants with longstanding and severe short bowel syndrome, employing blue food color appearance, breath hydrogen testing, and radio-opaque markers as measures of transit time. Absorption of energy, protein, fat, and fluid was conducted by classic nutrient balance methods. Diarrhea was estimated by daily stool weight and number of bowel actions. Although 8 patients were enrolled, only 7 completed the study. Transit time was not significantly different between oleic acid and placebo treatment, although peptide YY levels trended higher with the oleic acid treatment. Energy absorption was reduced 14% by oleic acid, significantly more than the 3% reduction by placebo. Fat, protein, and fluid absorption was not changed significantly. Neither diarrhea nor patient body weight was changed by oleic acid. Energy absorption is reduced by oleic acid supplements in severe short bowel syndrome. The study may have lacked power to determine whether oleic acid affects diarrhea or body weight.

Absorption of the laser radiation by the laser plasma with gas microjet targets

NASA Astrophysics Data System (ADS)

Borisevichus, D. A.; Zabrodskii, V. V.; Kalmykov, S. G.; Sasin, M. E.; Seisyan, R. P.

2017-01-01

An upper limit of absorption of the laser radiation in the plasma produced in a gas jet Xe target with the average density of (3-6) × 1018 cm-3 and the effective diameter of 0.7 mm is found. It is equal to ≈50% and remains constant under any variation in this range of densities. This result contradicts both theoretical assessments that have predicted virtually complete absorption and results of earlier experiments with the laser spark in an unlimited stationary Xe gas with the same density, where the upper limit of absorption was close to 100%. An analysis shows that nonlinearity of absorption and plasma nonequilibrium lead to the reduction of the absorption coefficient that, along with the limited size of plasma, can explain the experimental results.

Degradation of phytic acid in cereal porridges improves iron absorption by human subjects.

PubMed

Hurrell, Richard F; Reddy, Manju B; Juillerat, Marcel-A; Cook, James D

2003-05-01

Phytic acid in cereal-based and legume-based complementary foods inhibits iron absorption. Low iron absorption from cereal porridges contributes to the high prevalence of iron deficiency in infants from developing countries. The objective was to measure the influence of phytic acid degradation on iron absorption from cereal porridges. An exogenous phytase was used to fully degrade phytic acid during the manufacture of 9 roller-dried complementary foods based on rice, wheat, maize, oat, sorghum, and a wheat-soy blend. Iron absorption from the phytate-free and native phytate porridges prepared with water or milk (wheat only) was measured in adult humans with an extrinsic-label radioiron technique. Ascorbic acid was added to some porridges. When the foods were reconstituted with water, dephytinization increased iron absorption from rice porridge from 1.73% to 5.34% (P < 0.001), from oat from 0.33% to 2.79% (P < 0.0001), from maize from 1.80% to 8.92% (P < 0.0001), from wheat from 0.99% to 11.54% (P < 0.0001), from the wheat-soy blend without ascorbic acid from 1.15% to 3.75% (P < 0.005), and from the wheat-soy blend with ascorbic acid from 2.40% to 8.46% (P < 0.005). Reconstituting wheat porridge with milk instead of water markedly decreased or completely removed the enhancing effect of dephytinization on iron absorption in the presence and absence of ascorbic acid. Dephytinization did not increase iron absorption from high-tannin sorghum porridge reconstituted with water but increased iron absorption from low-tannin sorghum porridge by approximately 2-fold (P < 0.01). Phytate degradation improves iron absorption from cereal porridges prepared with water but not with milk, except from high-tannin sorghum.

AMMONIA ABSORPTION/AMMONIUM BISULFATE REGENERATION PILOT PLANT FOR FLUE GAS DESULFURIZATION

EPA Science Inventory

The report gives results of a pilot-plant study of the ammonia absorption/ammonium bisulfate regeneration process for removing SO2 from the stack gas of coal-fired power plants. Data were developed on the effects of such operating variable in the absorption of SO2 by ammoniacal l...

Ultrafast carrier dynamics of titanic acid nanotubes investigated by transient absorption spectroscopy.

PubMed

Wang, Li; Zhao, Hui; Pan, Lin Yun; Weng, Yu Xiang; Nakato, Yoshihiro; Tamai, Naoto

2010-12-01

Carrier dynamics of titanic acid nanotubes (phase of H2Ti2O5.H2O) deposited on a quartz plate was examined by visible/near-IR transient absorption spectroscopy with an ultraviolet excitation. The carrier dynamics of titanic acid nanotubes follows the fast trapping process which attributed to the intrinsic tubular structure, the relaxation of shallow trapped carriers and the recombination as a second-order kinetic process. Transient absorption of titanic acid nanotubes was dominated by the absorption of surface-trapped holes in visible region around 500 nm, which was proved by the faster decay dynamics in the presence of polyvinyl alcohol as a hole-scavenger. However, the slow relaxation of free carriers was much more pronounced in the TiO2 single crystals, as compared with the transient absorption spectra of titanic acid nanotubes under the similar excitation.

Repetitively Mode-Locked Cavity-Enhanced Absorption Spectroscopy (RML-CEAS) for Near-Infrared Gas Sensing

PubMed Central

Zheng, Chuantao; Wang, Yiding

2017-01-01

A Pound-Drever-Hall (PDH)-based mode-locked cavity-enhanced sensor system was developed using a distributed feedback diode laser centered at 1.53 µm as the laser source. Laser temperature scanning, bias control of the piezoelectric ceramic transducer (PZT) and proportional-integral-derivative (PID) feedback control of diode laser current were used to repetitively lock the laser modes to the cavity modes. A gas absorption spectrum was obtained by using a series of absorption data from the discrete mode-locked points. The 15 cm-long Fabry-Perot cavity was sealed using an enclosure with an inlet and outlet for gas pumping and a PZT for cavity length tuning. The performance of the sensor system was evaluated by conducting water vapor measurements. A linear relationship was observed between the measured absorption signal amplitude and the H2O concentration. A minimum detectable absorption coefficient of 1.5 × 10–8 cm–1 was achieved with an averaging time of 700 s. This technique can also be used for the detection of other trace gas species by targeting the corresponding gas absorption line. PMID:29207470

Post-discharge gas composition of a large-gap DBD in humid air by UV-Vis absorption spectroscopy

NASA Astrophysics Data System (ADS)

Moiseev, T.; Misra, N. N.; Patil, S.; Cullen, P. J.; Bourke, P.; Keener, K. M.; Mosnier, J. P.

2014-12-01

Large gap dielectric barrier discharges (DBD) provide non-thermal, non-equilibrium plasmas that can generate specific gas chemistry with enhanced bactericidal effects when working in humid air. The present study investigates the post-discharge gas composition of such plasmas operated in humid air using UV-Vis (200-800 nm) absorption spectroscopy. Absorbance spectra have been de-convoluted using direct deconvolution and iterative methods and results are correlated to the DBD electrical parameters. The high-voltage (56 and 70 kV rms) DBD plasma generated at 50 Hz frequency in a closed container over a 20 mm gap in air with relative humidity (RH) of 5-70% has been characterized by I-V and capacitive methods. The post-discharge gas composition at each RH is assessed by UV-Vis absorption spectroscopy for plasma exposure times of 15-120 s. The concentration of ozone and nitrogen oxides (O3, NO2, NO3, N2O4) increases with plasma exposure time but a strong decrease in [O3] levels is obtained with increase in RH. The decrease in [O3] and an abundance of nitrogen oxides is ascribed to high specific power densities in the closed container and to increasing RH levels. The absorbance residual following deconvolution shows a strong band at 230-270 nm consistent with the presence of pernitric acid (HNO4) and other HNOx (x = 1, 3) species. Humid air large gap DBD plasmas in closed containers generate along with O3, high levels of nitrogen oxides and HNOx (x = 1, 4) acids leading to increased bactericidal rates.

A randomised cross-over trial in healthy adults indicating improved absorption of omega-3 fatty acids by pre-emulsification

PubMed Central

Garaiova, Iveta; Guschina, Irina A; Plummer, Sue F; Tang, James; Wang, Duolao; Plummer, Nigel T

2007-01-01

Background The health benefits of increased intakes of omega-3 fatty acids are well established but palatability often presents a problem. The process of emulsification is used in the food industry to provide a wider spectrum of use, often with the result of increased consumption. Moreover, as emulsification is an important step in the digestion and absorption of fats, the pre-emulsification process may enhance digestion and absorption. In this study the levels of plasma fatty acid and triacylglycerol (TAG) following the ingestion of either an oil mixture or an emulsified oil mixture have been compared. Methods In this randomised cross-over study, 13 volunteers received the oil mixture and 11 received the oil emulsion as part of an otherwise fat free meal. Blood samples were collected at 0, 1.5, 3, 4.5, 6, 7.5 and 9 hours after ingestion of oil, separated and stored at -20°C. Plasma triacylglycerols were assessed spectrophotometrically and fatty acids were determined by gas chromatography. Following a washout period of twenty days the procedure was repeated with the assignments reversed. Results The postprandial plasma TAG and the C18:3 (n-6), C18:3(n-3), C20:5(n-3) and C22:6 (n-3) polyunsaturated fatty acid (PUFA) levels for the emulsified oil group were increased significantly (P = 0.0182; P = 0.0493; P = 0.0137; P < 0.0001; P = 0.0355 respectively) compared with the non-emulsified oil group. The C16:0 and C18:0 saturated fatty acids, the C18:1 (n-9) monounsaturated fatty acid and the C18:2 PUFA were not significantly different for the oil and emulsified oil groups. Conclusion Pre-emulsification of an oil mixture prior to ingestion increases the absorption of longer chain more highly unsaturated fatty acids (especially eicosapentaenoic acid and docosahexaenoic acid) but does not affect absorption of shorter chain less saturated fatty acids, suggesting that pre-emulsification of fish oils may be a useful means of boosting absorption of these beneficial fatty

Influence of short-chain fatty acids on iron absorption by proximal colon.

PubMed

Bouglé, D; Vaghefi-Vaezzadeh, N; Roland, N; Bouvard, G; Arhan, P; Bureau, F; Neuville, D; Maubois, J L

2002-09-01

Short-chain fatty acids produced by bacterial fermentation in the colon enhance the local absorption of cations, such as calcium, that could be used to improve the bioavailability of iron if a significant colonic absorption of iron were to occur. Iron (iron gluconate, 100 microM) absorption by the caecum of the rat was compared with that in proximal sites of the small bowel using the Ussing chamber model; the influence of probiotic bacteria (Propionibacterium freudenreichii) on iron absorption was assessed and compared with that of two of their fermentation products (acetic and propionic acids) using the Ussing chamber and the ligated colon with gamma emitting iron as experimental models. The caecum absorbed less iron than the duodenum, but significantly more than the jejunum and ileum. This occurred mainly through an enhanced mucosal transfer of iron uptake. Propionibacteria enhanced iron absorption from the proximal colon; the same effect was observed in the presence of viable bacteria, or the culture medium free of viable bacteria, or acetate and propionate or propionate alone. The proximal colon could be a significant site available for iron absorption; this absorption can be enhanced by local production of short-chain fatty acids such as propionate.

Chemical and spectral behavior of nitric acid in aqueous sulfuric acid solutions: Absorption spectrum and molar absorption coefficient of nitronium ion

NASA Astrophysics Data System (ADS)

Ershov, Boris G.; Panich, Nadezhda M.

2018-01-01

The chemical species formed from nitric acid in aqueous solutions of sulfuric acid (up to 18.0 mol L- 1) were studied by optical spectroscopy method. The concentration region of nitronium ion formation was identified and NO2+ ion absorption spectrum was measured (λmax ≤ 190 nm and ε190 = 1040 ± 50 mol- 1 L cm- 1).

Diode laser absorption sensors for gas-dynamic and combustion flows

NASA Technical Reports Server (NTRS)

Allen, M. G.

1998-01-01

Recent advances in room-temperature, near-IR and visible diode laser sources for tele-communication, high-speed computer networks, and optical data storage applications are enabling a new generation of gas-dynamic and combustion-flow sensors based on laser absorption spectroscopy. In addition to conventional species concentration and density measurements, spectroscopic techniques for temperature, velocity, pressure and mass flux have been demonstrated in laboratory, industrial and technical flows. Combined with fibreoptic distribution networks and ultrasensitive detection strategies, compact and portable sensors are now appearing for a variety of applications. In many cases, the superior spectroscopic quality of the new laser sources compared with earlier cryogenic, mid-IR devices is allowing increased sensitivity of trace species measurements, high-precision spectroscopy of major gas constituents, and stable, autonomous measurement systems. The purpose of this article is to review recent progress in this field and suggest likely directions for future research and development. The various laser-source technologies are briefly reviewed as they relate to sensor applications. Basic theory for laser absorption measurements of gas-dynamic properties is reviewed and special detection strategies for the weak near-IR and visible absorption spectra are described. Typical sensor configurations are described and compared for various application scenarios, ranging from laboratory research to automated field and airborne packages. Recent applications of gas-dynamic sensors for air flows and fluxes of trace atmospheric species are presented. Applications of gas-dynamic and combustion sensors to research and development of high-speed flows aeropropulsion engines, and combustion emissions monitoring are presented in detail, along with emerging flow control systems based on these new sensors. Finally, technology in nonlinear frequency conversion, UV laser materials, room

Methods for deacidizing gaseous mixtures by phase enhanced absorption

DOEpatents

Hu, Liang

2012-11-27

An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

Silicon on silicon dioxide slot waveguide evanescent field gas absorption sensor

NASA Astrophysics Data System (ADS)

Butt, M. A.; Khonina, S. N.; Kazanskiy, N. L.

2018-01-01

Several trace gases such as H2O, CO, CO2, NO, N2O, NO2 and CH4 strongly absorb in the mid-IR spectral region due to their fundamental rotational and vibrational transitions. In this work, we propose an evanescent field absorption gas sensor based on silicon/silicon dioxide slot waveguide at 3.39 μm for sensing of methane gas. These waveguides can provide the highest evanescent field ratio (EFR) > 47% with adequate dimensions. Higher EFR values often come at an expense of higher propagation losses. These waveguides have relatively higher losses as compared to conventional waveguides, such as rib and slab waveguides, as these fundamental losses are static and the proposed sensing mechanism is established on the incremental loss due to the absorption of the gas. Therefore, incident power can always be incremented to compensate the waveguide losses.

Plasmonic nanopatch array with integrated metal–organic framework for enhanced infrared absorption gas sensing

DOE PAGES

Chong, Xinyuan; Kim, Ki-joong; Zhang, Yujing; ...

2017-06-06

In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal–organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO 2) with high capacity. Additionally, experimental results show that this hybrid plasmonic–MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. Lastly, the demonstration of infrared absorption spectroscopy of CO 2 using the hybrid plasmonic–MOF device proves amore » promising strategy for future on-chip gas sensing with ultra-compact size.« less

Plasmonic nanopatch array with integrated metal–organic framework for enhanced infrared absorption gas sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chong, Xinyuan; Kim, Ki-joong; Zhang, Yujing

In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal–organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO 2) with high capacity. Additionally, experimental results show that this hybrid plasmonic–MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. Lastly, the demonstration of infrared absorption spectroscopy of CO 2 using the hybrid plasmonic–MOF device proves amore » promising strategy for future on-chip gas sensing with ultra-compact size.« less

Numerical simulation of infrared radiation absorption for diagnostics of gas-aerosol medium by remote sensing data

NASA Astrophysics Data System (ADS)

Voitsekhovskaya, O. K.; Egorov, O. V.; Kashirskii, D. E.; Shefer, O. V.

2015-11-01

Calculated absorption spectra of the mixture of gases (H2O, CO, CO2, NO, NO2, and SO2) and aerosol (soot and Al2O3), contained in the exhausts of aircraft and rocket engines are demonstrated. Based on the model of gas-aerosol medium, a numerical study of the spectral dependence of the absorptance for different ratios of gas and aerosol components was carried out. The influence of microphysical and optical properties of the components of the mixture on the spectral features of absorption of gas-aerosol medium was established.

Changes of lipid and fatty acid absorption induced by high dose of citric acid ester and lecithin emulsifiers.

PubMed

Sadouki, Mohamed; Bouchoucha, Michel

2014-09-01

To describe the effect of two food emulsifiers, lecithin (E322) and citric acid esters of mono-and diglycerides of fatty acids (E472c), on the intestinal absorption of lipids. The experiment was conducted on 24 male Wistar rats randomly assigned in three groups. For two groups of six rats, 30% of the lipid intake was replaced with lecithin (L) or citric acid ester of mono and diglycerides, (E); the remaining 12 rats were the control group (C). Diet and fecal fat analysis was used to determine the apparent lipid absorption (ALA) and fatty acids. ALA was significantly lower in the group E than in the groups C and L (p < 0.001). ALA of long saturated chain fatty acids decreased while the length of the carbon chains increased, and this decrease was higher in the group E. E472c emulsifier decreased the intestinal absorption of lipids.

Stark effect spectrophone for continuous absorption spectra monitoring. [a technique for gas analysis

NASA Technical Reports Server (NTRS)

Kavaya, M. J. (Inventor)

1981-01-01

A Stark effect spectrophone using a pulsed or continuous wave laser having a beam with one or more absorption lines of a constituent of an unknown gas is described. The laser beam is directed through windows of a closed cell while the unknown gas to be modified flows continuously through the cell between electric field plates disposed in the cell on opposite sides of the beam path through the cell. When the beam is pulsed, energy absorbed by the gas increases at each point along the beam path according to the spectral lines of the constituents of the gas for the particular field strengths at those points. The pressure measurement at each point during each pulse of energy yields a plot of absorption as a function of electric field for simultaneous detection of the gas constituents. Provision for signal averaging and modulation is included.

Novel Semi-Parametric Algorithm for Interference-Immune Tunable Absorption Spectroscopy Gas Sensing

PubMed Central

Michelucci, Umberto; Venturini, Francesca

2017-01-01

One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance and alignment of the optical elements, they are affected by temperature changes and mechanical disturbances, giving rise to a drift of the signal. In this work, we present a novel semi-parametric algorithm that allows the extraction of a signal, like the spectroscopic absorption line of a gas molecule, from a background containing arbitrary disturbances, without having to make any assumption on the functional form of these disturbances. The algorithm is applied first to simulated data and then to oxygen absorption measurements in the presence of strong fringes.To the best of the authors’ knowledge, the algorithm enables an unprecedented accuracy particularly if the fringes have a free spectral range and amplitude comparable to those of the signal to be detected. The described method presents the advantage of being based purely on post processing, and to be of extremely straightforward implementation if the functional form of the Fourier transform of the signal is known. Therefore, it has the potential to enable interference-immune absorption spectroscopy. Finally, its relevance goes beyond absorption spectroscopy for gas sensing, since it can be applied to any kind of spectroscopic data. PMID:28991161

Kinetics study of carbon dioxide absorption reaction into the promoted methyldiethanolamine solution

NASA Astrophysics Data System (ADS)

Sitorus, Yasmikha Tiurlan Susanti; Taurina, Hanna Sucita; Altway, Ali; Rahmawati, Yeni; Nurkhamidah, Siti

2017-05-01

The absorption of carbon dioxide (CO2) is important in the industrial world. In industries, especially petrochemical, oil, and natural gas sectors, separation process of CO2 gas which is a corrosive gas (acid gas) is required. So, the separation process of CO2 gas stream is important, one of the methods used to remove CO2 from the gas stream is reactive absorption process using the promoted methyldiethanolamine (MDEA) solution. Therefore, this study is aimed to obtain the reaction kinetics data of CO2 absorption in MDEA solution using arginine as a promoter. Arginine was chosen because of its amino acid molecule which is reactive, so it can accelerate the reaction rate of MDEA. Moreover, this study also made a comparison between the reactivity of MDEA solution using arginine and MDEA solution using other promoters (glycine and piperazine) for CO2 absorption. The method used is absorption using laboratory scale of Wetted Wall Column (WWC) equipment at 1 atm. This study provides the reaction kinetics data information in order to optimize the separation process of CO2 in the industrialized world. The experimental results show that CO2 absorption rate at 323.15 K without any additon of arginine is 2.33 × 10-7 kmol/sec. By addition of 0.5 and 1 wt% of arginine, the absorption rate becomes 4 × 10-7 kmol/sec (2 times larger) and 6 × 10-7 kmol/sec (3 times larger). These results show that the addition of arginine as a promoter can increase the absorption rate of CO2 in MDEA solution and cover the weaknesses of MDEA solution. Based on the experimental result, the reaction kinetics constant for arginine is 1.91 × 1025 exp (-12296/T) (m3/kmol.s). Although, arginine reaction rate constant is lower than glycine and piperazine.

Drug-nutrient interactions: inhibition of amino acid intestinal absorption by fluoxetine.

PubMed

Urdaneta, E; Idoate, I; Larralde, J

1998-05-01

Fluoxetine is one of the most widely used antidepressants and nowadays it is also being used to manage obesity problems. In our laboratory we demonstrated that the drug inhibited sugar absorption (Monteiro et al. 1993). The aim of the present work was to determine the effect of fluoxetine on intestinal leucine absorption. Using a procedure of successive absorptions in vivo the drug diminished amino acid absorption by 30% (P < 0.001). Experiments in vitro in isolated jejunum also revealed a reduction in leucine uptake of 37% (P < 0.001). In both cases fluoxetine only affected mediated transport without altering diffusion. In a preparation enriched in basolateral membrane, fluoxetine inhibited the Na+,K(+)-ATPase (EC 3.6.1.37) activity (55%; P < 0.001) in a non-competitive manner with an inhibition constant (Ki) value of 0.92 mM. Leucine uptake by brush-border membrane vesicles was diminished by the drug (a reduction of 48% was observed at 30s, P < 0.001); only the apical Na(+)-dependent transport system of the amino acid was modified and the inhibition was non-competitive. Leucine uptake in the presence of lysine indicated that transporter B was involved. These results suggest that fluoxetine reduces leucine absorption by its action on the basolateral and apical membrane of the enterocyte; the nutritional status of the patients under drug treatment may be affected as neutral amino acid absorption is decreased.

Trace gas absorption spectroscopy using laser difference-frequency spectrometer for environmental application

NASA Technical Reports Server (NTRS)

Chen, W.; Cazier, F.; Boucher, D.; Tittel, F. K.; Davies, P. B.

2001-01-01

A widely tunable infrared spectrometer based on difference frequency generation (DFG) has been developed for organic trace gas detection by laser absorption spectroscopy. On-line measurements of concentration of various hydrocarbons, such as acetylene, benzene, and ethylene, were investigated using high-resolution DFG trace gas spectroscopy for highly sensitive detection.

[Determination a variety of acidic gas in air of workplace by Ion Chromatography].

PubMed

Li, Shiyong

2014-10-01

To establish a method for determination of a variety of acid gas in the workplace air by Ion Chromatography. (hydrofluoric acid, hydrogen chloride or hydrochloric acid, sulfur anhydride or sulfuric acid, phosphoric acid, oxalic acid). The sample in workplace air was collected by the porous glass plate absorption tube containing 5 ml leacheate. (Sulfuric acid fog, phosphoric acid aerosol microporous membrane after collection, eluted with 5 ml of eluent.) To separated by AS14+AG14 chromatography column, by carbonate (2.0+1.0) mmol/L (Na(2)CO(3)-NaHCO(3)) as eluent, flow rate of 1 ml/min, then analyzed by electrical conductivity detector. The retain time was used for qualitative and the peak area was used for quantitation. The each ion of a variety of acid gas in the air of workplace were excellent in carbonate eluent separation. The linear range of working curve of 0∼20 mg/L. The correlation coefficient r>0.999; lower detection limit of 3.6∼115 µg/L; quantitative limit of 0.012∼0.53 mg/L; acquisition of 15L air were measured, the minimum detection concentration is 0.004 0∼0.13 mg/m(3). The recovery rate is 99.7%∼101.1%. In the sample without mutual interference ions. Samples stored at room temperature for 7 days. The same analysis method, the detection of various acidic gases in the air of workplace, simple operation, good separation effect, high sensitivity, high detection efficiency, easy popularization and application.

Functionalizing a Tapered Microcavity as a Gas Cell for On-Chip Mid-Infrared Absorption Spectroscopy

PubMed Central

Mandon, Julien; Harren, Frans J. M.; Wolffenbuttel, Reinoud F.

2017-01-01

Increasing demand for field instruments designed to measure gas composition has strongly promoted the development of robust, miniaturized and low-cost handheld absorption spectrometers in the mid-infrared. Efforts thus far have focused on miniaturizing individual components. However, the optical absorption path that the light beam travels through the sample defines the length of the gas cell and has so far limited miniaturization. Here, we present a functionally integrated linear variable optical filter and gas cell, where the sample to be measured is fed through the resonator cavity of the filter. By using multiple reflections from the mirrors on each side of the cavity, the optical absorption path is elongated from the physical μm-level to the effective mm-level. The device is batch-fabricated at the wafer level in a CMOS-compatible approach. The optical performance is analyzed using the Fizeau interferometer model and demonstrated with actual gas measurements. PMID:28878167

Connecting the Interstellar Gas and Dust Properties in Distant Galaxies Using Quasar Absorption Systems

NASA Technical Reports Server (NTRS)

Aller, Monique C.; Dwek, Eliahu; Kulkarni, Varsha P.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam; Lackey, Kyle; Dwek, Eli; Beiranvand, Nassim;

Absorption from a mixture of seventeen free amino acids by the isolated small intestine of the rat.

PubMed Central

Gardner, M L

1976-01-01

Absorption and secretion from a mixture of seventeen free amino acids has been measured in isolated perfused rat small intestine. 2. The absorption rate of an amino acid from this mixture is proportional to its concentration in the perfusate and independent of its chemical constitution. The constant of proportionality is the same as that previously observed when the perfusate contained peptides as well as amino acids. 3. Amino acids are concentrated, on average, sixfold during passage across the mucosa, and the free amino acid composition of the secretion into the tissue fluid is very similar to that of the luminal perfusate. 4. Peptides do not appear to be added to the tissue fluid during absorption of free amino acids. 5. It is concluded that the mechanisms for absorption of free amino acids are in general independent of those for absorption of peptides. PMID:1255532

Backscatter absorption gas imaging systems and light sources therefore

DOEpatents

Kulp, Thomas Jan [Livermore, CA; Kliner, Dahv A. V. [San Ramon, CA; Sommers, Ricky [Oakley, CA; Goers, Uta-Barbara [Campbell, NY; Armstrong, Karla M [Livermore, CA

2006-12-19

The location of gases that are not visible to the unaided human eye can be determined using tuned light sources that spectroscopically probe the gases and cameras that can provide images corresponding to the absorption of the gases. The present invention is a light source for a backscatter absorption gas imaging (BAGI) system, and a light source incorporating the light source, that can be used to remotely detect and produce images of "invisible" gases. The inventive light source has a light producing element, an optical amplifier, and an optical parametric oscillator to generate wavelength tunable light in the IR. By using a multi-mode light source and an amplifier that operates using 915 nm pump sources, the power consumption of the light source is reduced to a level that can be operated by batteries for long periods of time. In addition, the light source is tunable over the absorption bands of many hydrocarbons, making it useful for detecting hazardous gases.

Effect of tannic acid on iron absorption in straw-colored fruit bats (Eidolon helvum).

PubMed

Lavin, Shana R; Chen, Zhensheng; Abrams, Steven A

2010-01-01

Excessive absorption and subsequent storage of dietary iron has been found in a variety of captively held birds and mammals, including fruit bats. It is thought that feeding a diet that is low in iron can prevent the onset of this disease; however, manufacturing a diet with commonly available foodstuffs that contains a sufficiently low iron concentration is difficult. An alternative is to feed captive animals that may be susceptible to this disease potential iron chelators such as tannins that may bind to iron and block its absorption. Using stable isotope methods established in humans, we measured iron bioavailability in straw-colored fruit bats (Eidolon helvum) and tested whether tannic acid significantly reduced the extent of iron absorption. Regardless of dose, tannic acid significantly reduced iron absorption (by 40%) and in the absence of tannic acid, iron absorption was extensive in this species (up to 30%), more so than in humans. Species susceptible to iron storage disease may efficiently absorb iron in the gut regardless of iron status, and supplementing these species with tannic acid in captivity may provide an alternative or additional means of preventing the development of this disease. (c) 2009 Wiley-Liss, Inc.

Ultraviolet absorption by highly ionized halo gas near the Galactic center

NASA Technical Reports Server (NTRS)

Savage, B. D.; Massa, D.

1985-01-01

Initial results are presented for a program to survey highly ionized gas in the Milky Way disk and halo. High-resolution IUE (International Ultraviolet Explorer) far-UV spectra were obtained for 12 stars at galactocentric distances less than 6 kpc. The stars are 0.7-2.2 kpc away from the plane. Most of the spectra contain exceedingly strong and broad interstellar absorption lines of weakly and highly ionized atoms. In addition to the normally strong lines of Si IV and C IV, strong interstellar NV lines have been detected in the spectra of eight stars. The detection of NV absorption (amounting to more than 10 times the predicted NV) provides an important new constraint on models for the origin of Galactic halo gas. A Galactic fountain operating in the presence of known UV and EUV radiation might explain the observations.

Optical analysis of trapped Gas—Gas in Scattering Media Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Svanberg, S.

2010-01-01

An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. The technique investigates sharp gas spectral signatures, typically 10000 times sharper than those of the host material, in which the gas is trapped in pores or cavities. The presence of pores causes strong multiple scattering. GASMAS combines narrow-band diode-laser spectroscopy, developed for atmospheric gas monitoring, with diffuse media optical propagation, well-known from biomedical optics. Several applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, and this is also true for haemoglobin, making propagation possible in many natural materials. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities (frontal, maxillary and mastoideal) have been studied, demonstrating new possibilities for characterization and diagnostics. Transport of gas in porous media (diffusion) can be studied by first subjecting the material to, e.g., pure nitrogen, and then observing the rate at which normal, oxygen-containing air, reinvades the material. The conductance of the passages connecting a sinus with the nasal cavity can be objectively assessed by observing the oxygen gas dynamics when flushing the nose with nitrogen. Drying of materials, when liquid water is replaced by air and water vapour, is another example of dynamic processes which can be studied. The technique has also been extended to remote-sensing applications (LIDAR-GASMAS or Multiple-Scattering LIDAR).

The effect of amino acids on the intestinal absorption of immunoglobulins in the neonatal rat

PubMed Central

Bamford, D. R.; Donnelly, H.

1974-01-01

An in vitro preparation of 10-day-old rat intestine was used to examine the absorption of a number of amino acids and immunoglobulins. Evidence was obtained for the active absorption of alanine, leucine, methionine, histidine and lysine, but not for aspartic acid. A selective absorption of the homologous molecule was found in experiments where 131I-labelled rat and bovine IgG were presented to the ileum in 10-minute incubations. The greater uptake of rat IgG was unrelated to the relative rates of catabolism of the two molecules. Although the uptake of rat IgG was unaffected by 100 mM concentrations of neutral and acidic amino acids, the basic amino acids arginine and lysine significantly stimulated uptake. PMID:4854740

Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments.

PubMed

Kjær, Christina; Stockett, Mark H; Pedersen, Bjarke M; Nielsen, Steen Brøndsted

2016-12-01

The microenvironments in photosynthetic proteins affect the absorption by chlorophyll (Chl) pigments. It is, however, a challenge to disentangle the impact on the transition energies of different perturbations, for example, the global electrostatics of the protein (nonbonded environmental effects), exciton coupling between Chl's, conformational variations, and binding of an axial ligand to the magnesium center. This is needed to distinguish between the two most commonly proposed mechanisms for energy transport in photosynthetic proteins, relying on either weakly or strongly coupled pigments. Here, on the basis of photodissociation action spectroscopy, we establish that the redshift of the Soret absorption band due to binding of a negatively charged carboxylate (as present in aspartic acid and glutamic acid residues) is 0.1-0.2 eV for Chl a and b. This effect is almost enough to reproduce the well-known green color of plants and can account for the strong spectral variation between Chl's. The experimental data serve to benchmark future high-level calculations of excited-state energies. Finally, we demonstrate that complexes between Chl a and histidine, tagged by a quaternary ammonium ion, can be made in the gas phase by electrospray ionization, but more work is needed to produce enough ions for gas-phase spectroscopy.

[Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].

PubMed

Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

2009-08-01

The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection.

Effect of Acid-Base Equilibrium on Absorption Spectra of Humic acid in the Presence of Copper Ions

NASA Astrophysics Data System (ADS)

Lavrik, N. L.; Mulloev, N. U.

2014-03-01

The reaction between humic acid (HA, sample IHSS) and a metal ion (Cu2+) that was manifested as absorption bands in the range 210-350 nm was recorded using absorption spectroscopy. The reaction was found to be more effective as the pH increased. These data were interpreted in the framework of generally accepted concepts about the influence of acid-base equilibrium on the dissociation of salts, according to which increasing the solution pH increases the concentration of HA anions. It was suggested that [HA-Cu2+] complexes formed.

Combined NO/sub x//SO/sub 2/ removal from flue gas using ferrous chelates of SH-containing amino acids and alkali

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, D.K.; Chang, S.G.

1987-04-01

We report herein the use of ferrous chelates of SH-containing amino acids including cysteine, penicillamine, N-acetylcysteine, and N-acetylpenicillamine in neutral or alkaline solutions for the combined removal of NO and SO/sub 2/ in wet flue gas clean-up systems. These SH-containing amino acids not only can stabilize ferrous ions in alkaline solutions to promote the absorption of NO, but are also capable of rapidly reducing ferric ions formed during the scrubbing process back to ferrous ions. The disulfide form of the above amino acids can be reduced by SO/sub 2/ and H/sub 2/S to regenerate the starting monomeric species. The chemistrymore » relevant to the absorption of NO by the above ferrous chelates and the ligand regeneration process will be discussed.« less

Combined NO/sub x//SO/sub 2/ removal from flue gas using ferrous chelates of SH-containing amino acids and alkali

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, D.K.; Chang, S.G.

1987-01-01

We report herein the use of ferrous chelates of SH-containing amino acids including cysteine, penicillamine, N-acetylcysteine, and N-acetylpenicillamine in neutral or alkaline solutions for the combined removal of NO and SO/sub 2/ in wet flue gas clean-up systems. These SH-containing amino acids not only can stabilize ferrous ions in alkaline solutions to promote the absorption of NO, but are also capable of rapidly reducing ferric ions formed during the scrubbing process back to ferrous ions. The disulfide from of the above amino acids can be reduced by SO/sub 2/ and H/sub 2/S to regenerate the starting monomeric species. The chemistrymore » relevant to the absorption of NO by the above ferrous chelates and the ligand regeneration process will be discussed.« less

Transporter-targeted cholic acid-cytarabine conjugates for improved oral absorption.

PubMed

Zhang, Dong; Li, Dongpo; Shang, Lei; He, Zhonggui; Sun, Jin

2016-09-10

Cytarabine has a poor oral absorption due to its rapid deamination and poor membrane permeability. Bile acid transporters are highly expressed both in enterocytes and hepatocytes and to increase the oral bioavailability and investigate the potential application of cytarabine for liver cancers, a transporter- recognizing prodrug strategy was applied to design and synthesize four conjugates of cytarabine with cholic acid (CA), chenodeoxycholic acid (CDCA), hyodeoxycholic acid (HDCA) and ursodeoxycholic acid (UDCA). The anticancer activities against HepG2 cells were evaluated by MTT assay and the role of bile acid transporters during cellular transport was investigated in a competitive inhibition experiment. The in vitro and in vivo metabolic stabilities of these conjugates were studied in rat plasma and liver homogenates. Finally, an oral bioavailability study was conducted in rats. All the cholic acid-cytarabine conjugates (40μM) showed potent antiproliferative activities (up to 70%) against HepG2 cells after incubation for 48h. The addition of bile acids could markedly reduce the antitumor activities of these conjugates. The N(4)-ursodeoxycholic acid conjugate of cytarabine (compound 5) exhibited optimal stability (t1/2=90min) in vitro and a 3.9-fold prolonged half-life of cytarabine in vivo. More importantly, compound 5 increased the oral bioavailability 2-fold compared with cytarabine. The results of the present study suggest that the prodrug strategy based on the bile acid transporters is suitable for improving the oral absorption and the clinical application of cytarabine. Copyright © 2016 Elsevier B.V. All rights reserved.

Multi-gas interaction modeling on decorated semiconductor interfaces: A novel Fermi distribution-based response isotherm and the inverse hard/soft acid/base concept

NASA Astrophysics Data System (ADS)

Laminack, William; Gole, James

2015-12-01

A unique MEMS/NEMS approach is presented for the modeling of a detection platform for mixed gas interactions. Mixed gas analytes interact with nanostructured decorating metal oxide island sites supported on a microporous silicon substrate. The Inverse Hard/Soft acid/base (IHSAB) concept is used to assess a diversity of conductometric responses for mixed gas interactions as a function of these nanostructured metal oxides. The analyte conductometric responses are well represented using a combination diffusion/absorption-based model for multi-gas interactions where a newly developed response absorption isotherm, based on the Fermi distribution function is applied. A further coupling of this model with the IHSAB concept describes the considerations in modeling of multi-gas mixed analyte-interface, and analyte-analyte interactions. Taking into account the molecular electronic interaction of both the analytes with each other and an extrinsic semiconductor interface we demonstrate how the presence of one gas can enhance or diminish the reversible interaction of a second gas with the extrinsic semiconductor interface. These concepts demonstrate important considerations in the array-based formats for multi-gas sensing and its applications.

Effect of Feed Gas Flow Rate on CO2 Absorption through Super Hydrophobic Hollow Fiber membrane Contactor

NASA Astrophysics Data System (ADS)

Kartohardjono, Sutrasno; Alexander, Kevin; Larasati, Annisa; Sihombing, Ivander Christian

2018-03-01

Carbon dioxide is pollutant in natural gas that could reduce the heating value of the natural gas and cause problem in transportation due to corrosive to the pipeline. This study aims to evaluate the effects of feed gas flow rate on CO2 absorption through super hydrophobic hollow fiber contactor. Polyethyleneglycol-300 (PEG-300) solution was used as absorbent in this study, whilst the feed gas used in the experiment was a mixture of 30% CO2 and 70% CH4. There are three super hydrophobic hollow fiber contactors sized 6 cm and 25 cm in diameter and length used in this study, which consists of 1000, 3000 and 5000 fibers, respectively. The super hydrophobic fiber membrane used is polypropylene-based with outer and inner diameter of about 525 and 235 μm, respectively. In the experiments, the feed gas was sent through the shell side of the membrane contactor, whilst the absorbent solution was pumped through the lumen fibers. The experimental results showed that the mass transfer coefficient, flux, absorption efficiency for CO2-N2 system and CO2 loading increased with the feed gas flow rate, but the absorption efficiency for CO2-N2 system decreased. The mass transfer coefficient and the flux, at the same feed gas flow rate, decreased with the number of fibers in the membrane contactor, but the CO2 absorption efficiency and the CO2 loading increased.

Absorption of 5-aminosalicylic acid from colon and rectum.

PubMed Central

Bondesen, S; Schou, J B; Pedersen, V; Rafiolsadat, Z; Hansen, S H; Hvidberg, E F

1988-01-01

In order to clarify the characteristics of absorption of 5-aminosalicylic acid (5-ASA) from the colon, a neutral solution was instilled into the right part of the colon and the rectum, respectively, in six volunteers. A laxative (bisacodyl) and liquid meals were given prior to each instillation. No significant difference could be demonstrated between the two parts of the large bowel, but the absorption was considerably restricted compared with previous results obtained from the jejunum. The results confirm in a direct manner earlier observations on 5-ASA released from sulphasalazine. PMID:3358890

Intestinal absorption of the bile acid analogue 75Se-homocholic acid-taurine is increased in primary biliary cirrhosis, and reverts to normal during ursodeoxycholic acid administration

PubMed Central

Lanzini, A; De Tavonatti, M G; Panarotto, B; Scalia, S; Mora, A; Benini, F; Baisini, O; Lanzarotto, F

2003-01-01

Background: Whether ileal absorption of bile acid is up or downregulated in chronic cholestasis is still debated, and most evidence has come from animal studies. Aims: To compare ileal bile acid absorption in patients with primary biliary cirrhosis (PBC) and in healthy control subjects, and to assess the effect of ursodeoxycholic acid (UDCA). Patients: We studied 14 PBC patients before and during (n=11) UDCA administration, 14 healthy control subjects, and 14 Crohn’s disease patients (as disease controls). Methods: We used cholescintigraphy to measure retention in the enterohepatic circulation over five successive days of the bile acid analogue 75Se-homocholic acid-taurine (75SeHCAT) as an index of ileal bile acid absorption. Results were expressed as 75SeHCAT fractional turnover rate (FTR) and t½12. Results: 75SeHCAT FTR was 0.19 (0.11)/day, 0.34 (0.11)/day (p<0.001), and 0.83 (0.32)/day in PBC patients, healthy controls (p<0.0001), and Crohn’s patients (p<0.001), respectively, which increased to 0.36 (0.16)/day in PBC patients during UDCA treatment (p<0.005). 75SeHCAT t½12 was 4.8 (2.1) days in PBC patients, 2.2 (0.5) days (p<0.001) in healthy controls, and 1.0 (0.5) days (p<0.001) in Crohn’s disease patients. 75SeHCAT t½12 decreased to 2.2 (0.93) days (p< 0.001) in PBC patients during UDCA treatment. Conclusions: Our results support the concept that ileal bile acid absorption is upregulated in PBC patients, and that this effect may contribute towards damaging the cholestatic liver. This upregulation of bile acid absorption is abolished by UDCA. PMID:12912872

Intestinal absorption of the bile acid analogue 75Se-homocholic acid-taurine is increased in primary biliary cirrhosis, and reverts to normal during ursodeoxycholic acid administration.

PubMed

Lanzini, A; De Tavonatti, M G; Panarotto, B; Scalia, S; Mora, A; Benini, F; Baisini, O; Lanzarotto, F

2003-09-01

Whether ileal absorption of bile acid is up or downregulated in chronic cholestasis is still debated, and most evidence has come from animal studies. To compare ileal bile acid absorption in patients with primary biliary cirrhosis (PBC) and in healthy control subjects, and to assess the effect of ursodeoxycholic acid (UDCA). We studied 14 PBC patients before and during (n=11) UDCA administration, 14 healthy control subjects, and 14 Crohn's disease patients (as disease controls). We used cholescintigraphy to measure retention in the enterohepatic circulation over five successive days of the bile acid analogue (75)Se-homocholic acid-taurine ((75)SeHCAT) as an index of ileal bile acid absorption. Results were expressed as (75)SeHCAT fractional turnover rate (FTR) and t(1/2)12. (75)SeHCAT FTR was 0.19 (0.11)/day, 0.34 (0.11)/day (p<0.001), and 0.83 (0.32)/day in PBC patients, healthy controls (p<0.0001), and Crohn's patients (p<0.001), respectively, which increased to 0.36 (0.16)/day in PBC patients during UDCA treatment (p<0.005). (75)SeHCAT t(1/2)12 was 4.8 (2.1) days in PBC patients, 2.2 (0.5) days (p<0.001) in healthy controls, and 1.0 (0.5) days (p<0.001) in Crohn's disease patients. (75)SeHCAT t(1/2)12 decreased to 2.2 (0.93) days (p< 0.001) in PBC patients during UDCA treatment. Our results support the concept that ileal bile acid absorption is upregulated in PBC patients, and that this effect may contribute towards damaging the cholestatic liver. This upregulation of bile acid absorption is abolished by UDCA.

Viable, lyophilized lactobacilli do not increase iron absorption from a lactic acid-fermented meal in healthy young women, and no iron absorption occurs in the distal intestine.

PubMed

Bering, Stine; Sjøltov, Laila; Wrisberg, Seema S; Berggren, Anna; Alenfall, Jan; Jensen, Mikael; Højgaard, Liselotte; Tetens, Inge; Bukhave, Klaus

2007-11-01

Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, production of organic acids, or by the viable lactic acid bacteria. In this study the effect of a heat-inactivated lactic acid-fermented oat gruel with and without added viable, lyophilized Lactobacillus plantarum 299v on non-haem Fe absorption was investigated. Furthermore, Fe absorption in the distal intestine was determined. In a randomized, double-blinded crossover trial eighteen healthy young women aged 22 (SD 3) years with low Fe status (serum ferritin < 30 microg/l) were served the two test gruels, extrinsically labelled with 59Fe and served with two enterocoated capsules (containing 55Fe(II) and 55Fe(III), respectively) designed to disintegrate in the ileum. The meals were consumed on two consecutive days, e.g. in the order AA followed by BB in a second period. Non-haem Fe absorption was determined from 59Fe whole-body retention and isotope activities in blood samples. The concentrations of Fe, lactate, phytate, and polyphenols, and the pH were similar in the heat-inactivated lactic acid-fermented oat gruels with and without added L. plantarum 299v, and no difference in Fe absorption was observed between the test gruels (1.4 and 1.3%, respectively). Furthermore, no absorption of Fe in the distal intestine was observed. In conclusion, addition of viable, lyophilized lactobacillus to a heat-inactivated lactic acid-fermented oat gruel does not affect Fe absorption, and no absorption seems to occur in the distal part of the intestine from low Fe bioavailability meals in these women.

The Use of an Air-Natural Gas Flame in Atomic Absorption.

ERIC Educational Resources Information Center

Melucci, Robert C.

1983-01-01

Points out that excellent results are obtained using an air-natural gas flame in atomic absorption experiments rather than using an air-acetylene flame. Good results are obtained for alkali metals, copper, cadmium, and zinc but not for the alkaline earths since they form refractory oxides. (Author/JN)

Influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink in Jamaican children.

PubMed

Davidsson, L; Walczyk, T; Morris, A; Hurrell, R F

1998-05-01

The influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink (6.3 mg total Fe per serving) was evaluated with a stable-isotope technique in 20 6-7-y-old Jamaican children. Each child received two test meals labeled with 5.6 mg 57Fe and 3.0 mg 58Fe as ferrous sulfate on 2 consecutive days. Three different doses of ascorbic acid (0, 25, and 50 mg per 25-g serving) were evaluated in two separate studies by using a crossover design. Iron isotope ratios were measured by negative thermal ionization mass spectrometry. In the first study, iron absorption was significantly greater (P < 0.0001) after the addition of 25 mg ascorbic acid: geometric mean iron absorption was 1.6% (range: 0.9-4.2%) and 5.1% (2.2-17.3%) for the test meals containing 0 and 25 mg ascorbic acid, respectively. In the second study, a significant difference (P < 0.05) in iron absorption was observed when the ascorbic acid content was increased from 25 to 50 mg: geometric mean iron absorption was 5.4% (range: 2.7-10.8%) compared with 7.7% (range: 4.7-16.5%), respectively. The chocolate drink contained relatively high amounts of polyphenolic compounds, phytic acid, and calcium, all well-known inhibitors of iron absorption. The low iron absorption without added ascorbic acid shows that chocolate milk is a poor vehicle for iron fortification unless sufficient amounts of an iron-absorption enhancer are added. Regular consumption of iron-fortified chocolate milk drinks containing added ascorbic acid could have a positive effect on iron nutrition in population groups vulnerable to iron deficiency.

Absorption Kinetics of the Main Conjugated Linoleic Acid Isomers in Commercial-Rich Oil after Oral Administration in Rats.

PubMed

Rodríguez-Alcalá, Luís M; Ares, Irma; Fontecha, Javier; Martínez-Larrañaga, María-Rosa; Anadón, Arturo; Martínez, María-Aránzazu

2017-09-06

This study aimed to assess the oral absorption and plasma kinetics of two main isomers contained in commercial conjugated linoleic acid (CLA)-rich oil (Tonalin TG-80), rumenic acid (RA), and C18:2 trans-10, cis-12. The isomer plasma disposition after the single oral dose of 3000 mg of Tonalin TG-80/kg, containing 1200 mg/kg of each isomer, was studied in rats. The isomer plasma concentrations were determined by gas chromatography with flame ionization detection. The plasma kinetics showed rapid oral absorption of RA and C18:2 trans-10, cis-12 (t 1/2a 0.34 ± 0.09 and 0.53 ± 0.01 h) and slow elimination (t 1/2β 25.68 ± 3.29 and 18.12 ± 1.71 h); the maximal isomer plasma concentrations (C max ) of 8.48 ± 0.98 and 7.67 ± 0.80 μg mL -1 , respectively, were estimated at 2.08 ± 0.14 and 2.26 ± 0.11 h. Our results from a preclinical kinetic study in rats help to design future studies in humans for evaluating the CLA isomer dose-response.

Pinolenic Acid in Structured Triacylglycerols Exhibits Superior Intestinal Lymphatic Absorption As Compared to Pinolenic Acid in Natural Pine Nut Oil.

PubMed

Chung, Min-Yu; Woo, Hyunjoon; Kim, Juyeon; Kong, Daecheol; Choi, Hee-Don; Choi, In-Wook; Kim, In-Hwan; Noh, Sang K; Kim, Byung Hee

2017-03-01

The positional distribution pattern of fatty acids (FAs) in the triacylglycerols (TAGs) affects intestinal absorption of these FAs. The aim of this study was to compare lymphatic absorption of pinolenic acid (PLA) present in structured pinolenic TAG (SPT) where PLA was evenly distributed on the glycerol backbone, with absorption of pine nut oil (PNO) where PLA was predominantly positioned at the sn-3 position. SPT was prepared via the nonspecific lipase-catalyzed esterification of glycerol with free FA obtained from PNO. Lymphatic absorption of PLA from PNO and from SPT was compared in a rat model of lymphatic cannulation. Significantly (P < 0.05) greater amounts of PLA were detected in lymph collected for 8 h from an emulsion containing SPT (28.5 ± 0.7% dose) than from an emulsion containing PNO (26.2 ± 0.6% dose), thereby indicating that PLA present in SPT has a greater capacity for lymphatic absorption than PLA from PNO.

Gas separation using ultrasound and light absorption

DOEpatents

Sinha, Dipen N [Los Alamos, NM

2012-07-31

An apparatus and method for separating a chosen gas from a mixture of gases having no moving parts and utilizing no chemical processing is described. The separation of particulates from fluid carriers thereof has been observed using ultrasound. In a similar manner, molecular species may be separated from carrier species. It is also known that light-induced drift may separate light-absorbing species from carrier species. Therefore, the combination of temporally pulsed absorption of light with ultrasonic concentration is expected to significantly increase the efficiency of separation by ultrasonic concentration alone. Additionally, breaking the spatial symmetry of a cylindrical acoustic concentrator decreases the spatial distribution of the concentrated particles, and increases the concentration efficiency.

Determination of concentration and molar absorptivity of hypochlorous acid and hypobromous acid species by hydrogen peroxide titration

NASA Astrophysics Data System (ADS)

Uehara, H.; Arakaki, T.

2017-12-01

Hypochlorous acid and hypobromous acid (abbreviated as "HypoX acids") are the main ingredients of bleaching and bactericides. The HypoX acids change their chemical forms depending on environmental factors such as pH and various chemical reactions. For example, it has been reported that hypobromite ion in water changes to carcinogenic bromate by photochemical reaction with ultraviolet light. In this study, concentrations of HypoX acids were determined by UV-VIS absorbance measurement utilizing the fact that HypoX acids react with hydrogen peroxide and do not co-exist in the solution. The method for determining the concentration by titration with hydrogen peroxide can be carried out simpler and more efficiently than the DPD method or the current titration method generally used for chlorine concentration measurement. Molar absorptivity between 250 - 500 nm of HypoX acids, including their conjugate base species, was determined by solving theoretical acid-base formula including molar fraction of each chemical species at various pHs. Molar absorptivity of OCl- and OBr- between 250 - 500 nm was determined based on the concentrations obtained from titration with hydrogen peroxide and absorbance at pH > 10, where OCl- and OBr- dominate. Furthermore, the HypoX acids solutions were irradiated with a solar simulator, and the photolysis rate constants were obtained. Based on those values, the half-lives were calculated and the behavior of HypoX acids in the environment was elucidated.

Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

2016-07-01

Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

Measurement of nitrous acid (HONO) by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

NASA Astrophysics Data System (ADS)

Yi, Hongming; Maamary, Rabih; Gao, Xiaoming; Sigrist, Markus W.; Fertein, Eric; Chen, Weidong

2016-04-01

Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm-1 was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ~40 mm3) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by simultaneous measurements of direct HONO absorption spectra in a 109.5 m multipass cell using a distributed feedback (DBF) QCL. A minimum detection limit (MDL @ SNR=1) of 66 ppbv HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6×10-8 cm-1.W/Hz1/2. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding minimum detected absorption coefficient (SNR=1) is ~1.1×10-7 cm-1 (MDL: ~3 ppbv) in 1 s and ~1.1×10-8 cm-1 (MDL~330 pptv) in 150 s, respectively, with 1 W laser power. Acknowledgements The authors acknowledge financial supports from the CaPPA project (ANR-10-LABX-005) and the CPER CLIMIBIO program. References H. Yi, R. Maamary, X. Gao, M. W. Sigrist, E. Fertein, W. Chen, "Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy", Appl. Phys. Lett. 106 (2015) 101109

Semi-mechanistic modelling of ammonia absorption in an acid spray wet scrubber based on mass balance

USDA-ARS?s Scientific Manuscript database

A model to describe reactive absorption of ammonia (NH3) in an acid spray scrubber was developed as a function of the combined overall mass transfer coefficient K. An experimental study of NH3 absorption using 1% dilute sulphuric acid was carried out under different operating conditions. An empiric...

Absorption of ferulic acid from low-alcohol beer.

PubMed

Bourne, L; Paganga, G; Baxter, D; Hughes, P; Rice-Evans, C

2000-03-01

Flavonoids and monophenolic compounds have been well-described over recent years for their properties as antioxidants and scavengers of reactive oxygen and nitrogen species. A number of epidemiological studies implicate a role for flavonoids in reducing the risk of coronary heart disease. In particular, the focus has been on flavonol-rich fruit and vegetables and flavonoid-rich beverages, especially tea and red wine. Mechanisms of protection are unclear since the absorption, distribution, metabolism and elimination of dietary phenolics have not yet been extensively investigated. Here we report the bioavailability of ferulic acid, 4-hydroxy-3-methoxy-cinnamic acid, the major hydroxycinnamate in beer. Studies of the pharmacokinetics of urinary excretion of ferulic acid from low alcohol beer consumption in humans have been undertaken. The results show that ferulic acid is absorbed with a peak time for maximal excretion of ca. 8 h and the mean cumulative amount excreted is 5.8 +/- 3.2 mg. These findings are consistent with the uptake of ferulic acid from dietary sources, such as tomatoes, and suggest that ferulic acid is more bioavailable than individual dietary flavonoids and phenolics so far studied.

Genomic study of the absorption mechanism of p-coumaric acid and caffeic acid of extract of Ananas comosus L. leaves.

PubMed

Dang, Yun-jie; Zhu, Chun-yan

2015-03-01

Cardiac disease has emerged as the leading cause of death worldwide, and food rich in phenolic acids has drawn much attention as sources of active substances of hypolipidemic drug. Ananas comosus L. (pineapple) is one of the most popular tropical and subtropical fruits. Isolated from pineapple leaves, EAL(Extract of Ananas Comosus L. Leaves) is rich in phenolic acids, such as p-coumaric acid, caffeic acid, and other phenolics, highly relevant to the putative cardiovascular-protective effects, which suggests its potential to be a new plant medicine for treatment of cardiac disease, but little is known about absorption, distribution, metabolism, and excretion of EAL in animals or human beings. In this study, we employed cDNA microarray, Caco-2 cell lines, and rat intestinal model to explore the absorption behavior of p-coumaric acid and caffeic acid in EAL. The permeation of 2 substances was concentration and time dependent. Results also indicated that monocarboxylic acid transporter was involved in the transepithelial transport of p-coumaric acid and caffeic acid. © 2015 Institute of Food Technologists®

Gas trace detection with cavity enhanced absorption spectroscopy: a review of its process in the field

NASA Astrophysics Data System (ADS)

Liu, Siqi; Luo, Zhifu; Tan, Zhongqi; Long, Xingwu

2016-11-01

Cavity-enhanced absorption spectroscopy (CEAS) is a technology in which the intracavity absorption is deduced from the intensity of light transmitted by the high finesse optical cavity. Then the samples' parameters, such as their species, concentration and absorption cross section, would be detection. It was first proposed and demonstrated by Engeln R. [1] and O'Keefe[2] in 1998. This technology has extraordinary detection sensitivity, high resolution and good practicability, so it is used in many fields , such as clinical medicine, gas detection and basic physics research. In this paper, we focus on the use of gas trace detection, including the advance of CEAS over the past twenty years, the newest research progresses, and the prediction of this technology's development direction in the future.

Process for separating carbon dioxide from flue gas using sweep-based membrane separation and absorption steps

DOEpatents

Wijmans, Johannes G.; Baker, Richard W.; Merkel, Timothy C.

2012-08-21

A gas separation process for treating flue gases from combustion processes, and combustion processes including such gas separation. The invention involves routing a first portion of the flue gas stream to be treated to an absorption-based carbon dioxide capture step, while simultaneously flowing a second portion of the flue gas across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas to the combustor.

High reflected cubic cavity as long path absorption cell for infrared gas sensing

NASA Astrophysics Data System (ADS)

Yu, Jia; Gao, Qiang; Zhang, Zhiguo

2014-10-01

One direct and efficient method to improve the sensitivity of infrared gas sensors is to increase the optical path length of gas cells according to Beer-Lambert Law. In this paper, cubic shaped cavities with high reflected inner coating as novel long path absorption cells for infrared gas sensing were developed. The effective optical path length (EOPL) for a single cubic cavity and tandem cubic cavities were investigated based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) measuring oxygen P11 line at 763 nm. The law of EOPL of a diffuse cubic cavity in relation with the reflectivity of the coating, the port fraction and side length of the cavity was obtained. Experimental results manifested an increase of EOPL for tandem diffuse cubic cavities as the decrease of port fraction of the connecting aperture f', and the EOPL equaled to the sum of that of two single cubic cavities at f'<0.01. The EOPL spectra at infrared wavelength range for different inner coatings including high diffuse coatings and high reflected metallic thin film coatings were deduced.

Improving iron absorption from a Peruvian school breakfast meal by adding ascorbic acid or Na2EDTA.

PubMed

Davidsson, L; Walczyk, T; Zavaleta, N; Hurrell, R

2001-02-01

Iron-fortified school breakfasts have been introduced in Peru to combat childhood iron deficiency. We evaluated whether iron absorption from a school breakfast meal was improved by increasing the ascorbic acid content or by adding an alternative enhancer of iron absorption, Na2EDTA. In a crossover design, iron absorption from test meals was evaluated by erythrocyte incorporation of 58Fe and 57Fe. The test meals (wheat bread and a drink containing cereal, milk, and soy) contained 14 mg added Fe (as ferrous sulfate) including 2.0-2.6 mg 58Fe or 4.0-7.0 mg 57Fe. Geometric mean iron absorption increased significantly from 5.1% to 8.2% after the molar ratio of ascorbic acid to fortification iron was increased from 0.6:1 to 1.6:1 (P < 0.01; n = 9). Geometric mean iron absorption increased significantly from 2.9% to 3.8%, from 2.2% to 3.5%, and from 2.4% to 3.7% after addition of Na2EDTA at molar ratios relative to fortification iron of 0.3:1, 0.7:1, and 1:1, respectively, compared with test meals containing no added enhancers (P < 0.01; n = 10 for all). Iron absorption after addition of ascorbic acid (molar ratio 0.6:1) was not significantly different from that after addition of Na2EDTA (molar ratio 0.7:1). Ascorbic acid and Na2EDTA did not differ significantly in their enhancing effects on iron absorption at molar ratios of 0.6:1 to 0.7:1 relative to fortification iron. Additional ascorbic acid (molar ratio 1.6:1) increased iron absorption significantly. Increasing the molar ratio of Na2EDTA to fortification iron from 0.3:1 to 1:1 had no effect on iron absorption.

Pulsed laser linescanner for a backscatter absorption gas imaging system

DOEpatents

Kulp, Thomas J.; Reichardt, Thomas A.; Schmitt, Randal L.; Bambha, Ray P.

2004-02-10

An active (laser-illuminated) imaging system is described that is suitable for use in backscatter absorption gas imaging (BAGI). A BAGI imager operates by imaging a scene as it is illuminated with radiation that is absorbed by the gas to be detected. Gases become "visible" in the image when they attenuate the illumination creating a shadow in the image. This disclosure describes a BAGI imager that operates in a linescanned manner using a high repetition rate pulsed laser as its illumination source. The format of this system allows differential imaging, in which the scene is illuminated with light at least 2 wavelengths--one or more absorbed by the gas and one or more not absorbed. The system is designed to accomplish imaging in a manner that is insensitive to motion of the camera, so that it can be held in the hand of an operator or operated from a moving vehicle.

Ex Vivo and In Situ Evaluation of 'Dispelling-Wind' Chinese Medicine Herb-Drugs on Intestinal Absorption of Chlorogenic Acid.

PubMed

Zhai, Lixiang; Shi, Jun; Xu, Weitong; Heinrich, Michael; Wang, Jianying; Deng, Wenji

2015-12-01

This study aims to investigate the additive or synergistic effects and mechanism of intestinal absorption of extracts from two commonly used 'dispelling-wind' TCM botanical drugs [roots of Angelica dahurica (Hoffm.) Benth. & Hook. f. ex Franch. & Sav. (RAD) and Saposhnikovia divaricata (Turcz.) Schischk. (RSD)] using chlorogenic acid as a marker substance. Ex vivo everted intestinal sac and in situ single pass perfusion methods using rats were employed to investigate the effects of two TCM botanical drugs extracts on the intestinal absorption of chlorogenic acid. Both the extracts of RAD and RSD showed synergistic properties on the intestinal absorption of chlorogenic acid. The verapamil (a P-gp inhibitor) and intestinal dysbacteriosis model induced by norfloxacin increased the P(app) and K(a) of intestinal absorption of chlorogenic acid. These synergistic effects on intestinal absorption in a rat model can be correlated with the inhibition of P-gp and regulation of gut microbiota. This experimental approach has helped to better understand changes in the absorption of chlorogenic acid under different conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Using Willie's Acid-Base Box for Blood Gas Analysis

ERIC Educational Resources Information Center

Dietz, John R.

2011-01-01

In this article, the author describes a method developed by Dr. William T. Lipscomb for teaching blood gas analysis of acid-base status and provides three examples using Willie's acid-base box. Willie's acid-base box is constructed using three of the parameters of standard arterial blood gas analysis: (1) pH; (2) bicarbonate; and (3) CO[subscript…

Rare-gas impurities in alkali metals: Relation to optical absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meltzer, D.E.; Pinski, F.J.; Stocks, G.M.

1988-04-15

An investigation of the nature of rare-gas impurity potentials in alkali metals is performed. Results of calculations based on simple models are presented, which suggest the possibility of resonance phenomena. These could lead to widely varying values for the exponents which describe the shape of the optical-absorption spectrum at threshold in the Mahan--Nozieres--de Dominicis theory. Detailed numerical calculations are then performed with the Korringa-Kohn-Rostoker coherent-potential-approximation method. The results of these highly realistic calculations show no evidence for the resonance phenomena, and lead to predictions for the shape of the spectra which are in contradiction to observations. Absorption and emission spectramore » are calculated for two of the systems studied, and their relation to experimental data is discussed.« less

Scattered light and accuracy of the cross-section measurements of weak absorptions: Gas and liquid phase UV absorption cross sections of CH3CFCl2

NASA Technical Reports Server (NTRS)

Fahr, A.; Braun, W.; Kurylo, M. J.

1993-01-01

Ultraviolet absorption cross sections of CH3CFCl2(HCFC-141b) were determined in the gas phase (190-260 nm) and liquid phase (230-260 mm) at 298 K. The liquid phase absorption cross sections were then converted into accurate gas phase values using a previously described procedure. It has been demonstrated that scattered light from the shorter-wavelength region (as little as several parts per thousand) can seriously compromise the absorption cross-section measurement, particularly at longer wavelengths where cross sections are low, and can be a source of discrepancies in the cross sections of weakly absorbing halocarbons reported in the literature. A modeling procedure was developed to assess the effect of scattered light on the measured absorption cross section in our experiments, thereby permitting appropriate corrections to be made on the experimental values. Modeled and experimental results were found to be in good agreement. Experimental results from this study were compared with other available determinations and provide accurate input for calculating the atmospheric lifetime of HCFC-141b.

ISO ammonia line absorption reveals a layer of hot gas veiling Sgr B2

NASA Astrophysics Data System (ADS)

Ceccarelli, C.; Baluteau, J.-P.; Walmsley, M.; Swinyard, B. M.; Caux, E.; Sidher, S. D.; Cox, P.; Gry, C.; Kessler, M.; Prusti, T.

2002-02-01

We report the first results of the unbiased spectral high resolution survey obtained towards Sgr B2 with the Long Wavelength Spectrometer on board ISO. The survey detected more than one hundreds lines from several molecules. Ammonia is the molecule with the largest number (21) of detected lines in the survey. We detected NH3 transitions from levels with energies from 45 to 500 cm-1. The detected transitions are from both para and ortho ammonia and metastable and non-metastable levels. All the ammonia lines are in absortion against the FIR continuum of Sgr B2. With such a large number of detected lines in such a large range of energy levels, we could very efficiently constrain the main parameters of the absorbing gas layer. The gas is at (700 +/- 100) K and has a density lower than 104 cm-3. The total NH3 column density in the layer is (3+/- 1) x 1016 cm-2, equally shared between ortho and para ammonia. Given the derived relatively high gas temperature and ammonia column density, our observations support the hypothesis previously proposed of a layer of shocked gas between us and Sgr B2. We also discuss previous observations of far infrared line absorption from other molecules, like H2O and HF, in the light of this hot absorbing layer. If the absorption is done by the hot absorbing layer rather than by the warm envelope surrounding Sgr B2, as was previously supposed in order to interpret the mentioned observations, the derived H2O and HF abundances are one order of magitude larger than previously estimated. Yet, the present H2O and HF observations do not allow one to disentangle the absorption from the hot layer against the warm envelope. Our conclusions are hence that care should be applied when interpreting the absorption observations in Sgr B2, as the hot layer clearly seen in the ammonia transitions may substantially contribute to the absorption. ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The

Laser-absorption sensing of gas composition of products from coal gasification

NASA Astrophysics Data System (ADS)

Jeffries, Jay B.; Sur, Ritobrata; Sun, Kai; Hanson, Ronald K.

2014-06-01

A prototype in-situ laser-absorption sensor for the real-time composition measurement (CO, CH4, H2O and CO2) of synthesis gas products of coal gasification (called here syngas) was designed, tested in the laboratory, and demonstrated during field-measurement campaigns in a pilot-scale entrained flow gasifier at the University of Utah and in an engineering-scale, fluidized-bed transport gasifier at the National Carbon Capture Center (NCCC). The prototype design and operation were improved by the lessons learned from each field test. Laser-absorption measurements are problematic in syngas flows because efficient gasifiers operate at elevated pressures (10-50 atm) where absorption transitions are collision broadened and absorption transitions that are isolated at 1 atm become blended into complex features, and because syngas product streams can contain significant particulate, producing significant non-absorption scattering losses of the transmission of laser light. Thus, the prototype sensor used a new wavelength-scanned, wavelength-modulation spectroscopy strategy with 2f-detection and 1f-normalization (WMS-2f/1f) that can provide sensitive absorption measurements of species with spectra blended by collision broadening even in the presence of large non-absorption laser transmission losses (e.g., particulate scattering, beam steering, etc.). The design of the sensor for detection of CO, CH4, H2O and CO2 was optimized for the specific application of syngas monitoring at the output of large-scale gasifiers. Sensor strategies, results and lessons learned from these field measurement campaigns are discussed.

Lecithin inhibits fatty acid and bile salt absorption from rat small intestine in vivo.

PubMed

Saunders, D R; Sillery, J

1976-12-01

During digestion of a fatty meal, long chain free fatty acids (FFA) and lecithin are among the lipids solubilized in intestinal contents as mixed micelles with bile salts. We hypothesized that if lecithin were not hydrolyzed, the mixed micelles would be abnormal, and absorption of FFA and bile salts would be depressed. To test this hypothesis, isolated segments of rat small intestine were infused in vivo with micellar solutions of 2 mMolar linoleic acid and 10 mMolar taurocholate to which was added 3 mMolar 1-palmitoyl, 2-oleoyl lecithin (a common lecithin in bile and food), or 1-palmitoyl lysolecithin (the hydrolytic product of lecithin). Absorption of FFA and bile salt was measured under steady state conditions using a single-pass technique. Lecithin depressed the rate of FFA absorption by 40% (p less than 0.025) in jejunal and ileal segments whereas lysolecithin was associated with normal rates of FFA absorption. Lecithin also reduced taurocholate absorption from the ileum by 30% (p less than 0.05). These data support the idea that lecithin may depress FFA and bile salt absorption from the small intestine in pancreatic insufficiency.

Effect of three edible oils on the intestinal absorption of caffeic acid: An in vivo and in vitro study

PubMed Central

Prasadani, W. Chaturi; Senanayake, Chaturi M.; Jayathilaka, Nimanthi; Ekanayake, Sagarika

2017-01-01

Polyphenolic antioxidants are mainly absorbed through passive paracellular permeation regulated by tight junctions. Some fatty acids are known to modulate tight junctions. Fatty acids resulting from the digestion of edible oils may improve the absorption of polyphenolic antioxidants. Therefore, we explored the effect of three edible oils on the intestinal absorption of caffeic acid. Rats were fed with soybean oil and caffeic acid dissolved in distilled water. Caffeic acid contents in the plasma collected up to 1 hr were quantified. The experiment was repeated with coconut oil and olive oil. Component fatty acids of the oils were individually tested in vitro for their effect on permeability of caffeic acid using Caco-2 cell monolayers. Highest absorption of caffeic acid was observed in animals fed with coconut oil. In vitro transport percentages of caffeic acid in 2.5 mmol/L solutions of fatty acids were 22.01±0.12 (lauric), 15.30 ± 0.25 (myristic acid), 13.59 ± 0.35 (linoleic acid), 3.70 ± 0.09 (oleic acid) and 0.10–2.0 (all other fatty acids). Lauric acid and myristic acid are the two major fatty acids present in coconut oil. Therefore, these fatty acids may contribute to the higher absorption of caffeic acid in the presence of coconut oil. PMID:28617858

Determination of absorption coefficient based on laser beam thermal blooming in gas-filled tube.

PubMed

Hafizi, B; Peñano, J; Fischer, R; DiComo, G; Ting, A

2014-08-01

Thermal blooming of a laser beam propagating in a gas-filled tube is investigated both analytically and experimentally. A self-consistent formulation taking into account heating of the gas and the resultant laser beam spreading (including diffraction) is presented. The heat equation is used to determine the temperature variation while the paraxial wave equation is solved in the eikonal approximation to determine the temporal and spatial variation of the Gaussian laser spot radius, Gouy phase (longitudinal phase delay), and wavefront curvature. The analysis is benchmarked against a thermal blooming experiment in the literature using a CO₂ laser beam propagating in a tube filled with air and propane. New experimental results are presented in which a CW fiber laser (1 μm) propagates in a tube filled with nitrogen and water vapor. By matching laboratory and theoretical results, the absorption coefficient of water vapor is found to agree with calculations using MODTRAN (the MODerate-resolution atmospheric TRANsmission molecular absorption database) and HITRAN (the HIgh-resolution atmospheric TRANsmission molecular absorption database).

Determination of free and total sulfur(IV) compounds in coconut water using high-resolution continuum source molecular absorption spectrometry in gas phase.

PubMed

Oliveira, Michael L; Brandao, Geovani C; de Andrade, Jailson B; Ferreira, Sergio L C

2018-03-01

This work proposes a method for the determination of free and total sulfur(IV) compounds in coconut water samples, using the high-resolution continuum source molecular absorption spectrometry. It is based on the measurement of the absorbance signal of the SO 2 gas generate, which is resultant of the addition of hydrochloric acid solution on the sample containing the sulfating agent. The sulfite bound to the organic compounds is released by the addition of sodium hydroxide solution, before the generation of the SO 2 gas. The optimization step was performed using multivariate methodology involving volume, concentration and flow rate of hydrochloric acid. This method was established by the sum of the absorbances obtained in the three lines of molecular absorption of the SO 2 gas. This strategy allowed a procedure for the determination of sulfite with limits of detection and quantification of 0.36 and 1.21mgL -1 (for a sample volume of 10mL) and precision expressed as relative standard deviation of 5.4% and 6.4% for a coconut water sample containing 38.13 and 54.58mgL -1 of free and total sulfite, respectively. The method was applied for analyzing five coconut water samples from Salvador city, Brazil. The average contents varied from 13.0 to 55.4mgL -1 for free sulfite and from 24.7 to 66.9mgL -1 for total sulfur(IV) compounds. The samples were also analyzed employing the Ripper´s procedure, which is a reference method for the quantification of this additive. A statistical test at 95% confidence level demonstrated that there is no significant difference between the results obtained by the two methods. Copyright © 2017 Elsevier B.V. All rights reserved.

A multivariant study of the absorption properties of poly(glutaric-acid-glycerol) films

USDA-ARS?s Scientific Manuscript database

The solvent absorption into the matrix of poly(glutaric acid-glycerol) films made with or without either iminodiacetic acid, sugarcane bagasse, pectin, corn fiber gum or microcrystalline cellulose have been evaluated. The films were incubated in various solvent systems for 24h. The amounts of solve...

Water absorption, retention and the swelling characteristics of cassava starch grafted with polyacrylic acid.

PubMed

Witono, J R; Noordergraaf, I W; Heeres, H J; Janssen, L P B M

2014-03-15

An important application of starch grafted with copolymers from unsaturated organic acids is the use as water absorbent. Although much research has been published in recent years, the kinetics of water absorption and the swelling behavior of starch based superabsorbents are relatively unexplored. Also, water retention under mechanical strain is usually not reported. Cassava starch was used since it has considerable economic potential in Asia. The gelatinized starch was grafted with acrylic acid and Fenton's initiator and crosslinked with N,N'-methylenebisacrylamide (MBAM). Besides a good initial absorption capacity, the product could retain up to 63 g H2O/g under severe suction. The material thus combines a good absorption capacity with sufficient gel strength. The mathematical analysis of the absorption kinetics shows that at conditions of practical interest, the rate of water penetration into the gel is determined by polymer chain relaxations and not by osmotic driven diffusion. Copyright © 2013 Elsevier Ltd. All rights reserved.

MAPPING THE DYNAMICS OF COLD GAS AROUND SGR A* THROUGH 21 cm ABSORPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christian, Pierre; Loeb, Abraham, E-mail: pchristian@cfa.harvard.edu

2015-11-20

The presence of a circumnuclear stellar disk around Sgr A* and megamaser systems near other black holes indicates that dense neutral disks can be found in galactic nuclei. We show that depending on their inclination angle, optical depth, and spin temperature, these disks could be observed spectroscopically through 21 cm absorption. Related spectroscopic observations of Sgr A* can determine its HI disk parameters and the possible presence of gaps in the disk. Clumps of dense gas similar to the G2 could could also be detected in 21 cm absorption against Sgr A* radio emission.

Potential of single cationic amino acid molecule "Arginine" for stimulating oral absorption of insulin.

PubMed

Kamei, Noriyasu; Khafagy, El-Sayed; Hirose, Jun; Takeda-Morishita, Mariko

2017-04-15

We have reported that cell-penetrating peptides, such as oligoarginine, act as powerful absorption enhancers for the development of oral insulin delivery systems. However, the minimal essential sequence of oligoarginine that stimulates intestinal insulin absorption remains unclear. Therefore, the present study was conducted to clarify this minimum sequence of oligoarginine and to examine the effect of single cationic amino acid arginine on the intestinal and oral absorption of insulin. The results demonstrated that a remarkable enhancement of intestinal insulin absorption was observed after coadministration of insulin with l-arginine. The efficacy of d-forms of oligoarginine/arginine tended to decrease with a decreasing number of amino acid residues, whereas the effect of l-arginine was the strongest of any of the l-forms of oligoarginine/arginine. Interestingly, the effect of l-arginine was stronger than that of d-arginine at various concentrations, and the effect of other cationic amino acids such as lysine and histidine was relatively lower than that of arginine. In addition, no leakage of lactate dehydrogenase from the intestinal epithelium and no change in the transepithelial electrical resistance of a Caco-2 cell monolayer were detected after administration of l-arginine as the single amino acid, which suggests that there were no undesirable effects of arginine on the integrity of cell membranes and paracellular tight junctions. Oral administration study in mice demonstrated that the stronger hypoglycemic effects were observed after coadministration of insulin with l-arginine. In this study, we found that arginine is a key cationic amino acid for delivering insulin across intestinal epithelial barriers and hopefully accelerating the clinical development of oral insulin delivery systems. Copyright © 2017 Elsevier B.V. All rights reserved.

The Genealogical Tree of Ethanol: Gas-phase Formation of Glycolaldehyde, Acetic Acid, and Formic Acid

NASA Astrophysics Data System (ADS)

Skouteris, Dimitrios; Balucani, Nadia; Ceccarelli, Cecilia; Vazart, Fanny; Puzzarini, Cristina; Barone, Vincenzo; Codella, Claudio; Lefloch, Bertrand

2018-02-01

Despite the harsh conditions of the interstellar medium, chemistry thrives in it, especially in star-forming regions where several interstellar complex organic molecules (iCOMs) have been detected. Yet, how these species are synthesized is a mystery. The majority of current models claim that this happens on interstellar grain surfaces. Nevertheless, evidence is mounting that neutral gas-phase chemistry plays an important role. In this paper, we propose a new scheme for the gas-phase synthesis of glycolaldehyde, a species with a prebiotic potential and for which no gas-phase formation route was previously known. In the proposed scheme, the ancestor is ethanol and the glycolaldehyde sister species are acetic acid (another iCOM with unknown gas-phase formation routes) and formic acid. For the reactions of the new scheme with no available data, we have performed electronic structure and kinetics calculations deriving rate coefficients and branching ratios. Furthermore, after a careful review of the chemistry literature, we revised the available chemical networks, adding and correcting several reactions related to glycolaldehyde, acetic acid, and formic acid. The new chemical network has been used in an astrochemical model to predict the abundance of glycolaldehyde, acetic acid, and formic acid. The predicted abundance of glycolaldehyde depends on the ethanol abundance in the gas phase and is in excellent agreement with the measured one in hot corinos and shock sites. Our new model overpredicts the abundance of acetic acid and formic acid by about a factor of 10, which might imply a yet incomplete reaction network.

FIRST CONNECTION BETWEEN COLD GAS IN EMISSION AND ABSORPTION: CO EMISSION FROM A GALAXY–QUASAR PAIR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neeleman, Marcel; Prochaska, J. Xavier; Zwaan, Martin A.

2016-04-01

We present the first detection of molecular emission from a galaxy selected to be near a projected background quasar using the Atacama Large Millimeter/submillimeter Array (ALMA). The ALMA detection of CO(1−0) emission from the z = 0.101 galaxy toward quasar PKS 0439–433 is coincident with its stellar disk and yields a molecular gas mass of M{sub mol} ≈ 4.2 × 10{sup 9} M{sub ⊙} (for a Galactic CO-to-H{sub 2} conversion factor), larger than the upper limit on its atomic gas mass. We resolve the CO velocity field, obtaining a rotational velocity of 134 ± 11 km s{sup −1} and a resultant dynamical mass of ≥4 × 10{sup 10} M{sub ⊙}.more » Despite its high metallicity and large molecular mass, the z = 0.101 galaxy has a low star formation rate, implying a large gas consumption timescale, larger than that typical of late-type galaxies. Most of the molecular gas is hence likely to be in a diffuse extended phase, rather than in dense molecular clouds. By combining the results of emission and absorption studies, we find that the strongest molecular absorption component toward the quasar cannot arise from the molecular disk, but is likely to arise from diffuse gas in the galaxy’s circumgalactic medium. Our results emphasize the potential of combining molecular and stellar emission line studies with optical absorption line studies to achieve a more complete picture of the gas within and surrounding high-redshift galaxies.« less

Importance of the regiospecific distribution of long-chain saturated fatty acids on gut comfort, fat and calcium absorption in infants.

PubMed

Petit, Valérie; Sandoz, Laurence; Garcia-Rodenas, Clara L

2017-06-01

Gastrointestinal tolerance and fat and calcium (Ca) absorption are different between breast-fed (BF) and formula-fed (FF) infants. Certain components and/or structural particularities in human milk (HM), can contribute to favorable outcomes in BF infants. In HM, the long-chain saturated fatty acid (LCSFA) palmitic acid has a different stereospecific distribution (sn-2 position) compared to most infant formula (IF) (primarily sn-1, 3 positions), which may contribute to unfavorable outcomes. Evidence suggests palmitic acid is important in the formation of stool FA-mineral (or FA-Ca) soaps, associated with harder stools in FF infants. Partial replacement by structured palmitic acid-rich triacylglycerols (TAGs) promotes palmitic acid absorption. However, evidence for stool softening, improved fat absorption and reduced Ca excretion in stools is inconsistent. IFs with less palmitic acid can improve fat and Ca absorption, and stool consistency. The presence of other LCSFAs (myristic and stearic acids) in sn-1, 3 positions may also contribute to reduced absorption of fat and Ca, and stool hardness, in FF infants. Nevertheless, little attention has been given to modifying these other LCSFAs in IF. We review literature comparing the effect of HM and IF with different lipid compositions on stool patterns and/or fat and Ca absorption in healthy, term infants. Based on available data, we estimate a maximum level for sn-1, 3 LCSFAs of 13% of TAGs, under which fat and Ca absorption and stool consistency are improved. IF designed according to this threshold could efficiently improve nutrient absorption and stool patterns in healthy infants who cannot be breast-fed. Copyright © 2017 Elsevier Ltd. All rights reserved.

UV-Vis absorption spectra and electronic structure of merocyanines in the gas phase

NASA Astrophysics Data System (ADS)

Ishchenko, Alexander A.; Kulinich, Andrii V.; Bondarev, Stanislav L.; Raichenok, Tamara F.

2018-02-01

Gas-phase absorption spectra of a merocyanine vinylogous series have been studied for the first time. In vapour, their long-wavelength absorption bands were found to be considerably shifted hypsochromically, broader, more symmetrical, less intense, and their vinylene shift much smaller than even in low-polarity n-hexane. This indicates that in the gas phase their electronic structure closely approaches the nonpolar polyene limiting structure. The TDDFT calculations of the long-wavelength electronic transitions in the studied merocyanines in vacuo demonstrated good-to-excellent correlation - depending on the functional used - with the obtained experimental data. For comparison, the solvent effects was accounted for using the polarizable continuum model (PCM) with n-hexane and ethanol as low-polarity and high-polarity media, and compared with the UV-Vis spectral data in these solvents. In this case, the discrepancy between theory and experiment was much greater, increasing at that with the polymethine chain length.

Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses.

PubMed

Vasconcelos, Maydla Dos Santos; Passos, Wilson Espíndola; Lescanos, Caroline Honaiser; Pires de Oliveira, Ivan; Trindade, Magno Aparecido Gonçalves; Caires, Anderson Rodrigues Lima; Muzzi, Rozanna Marques

2018-01-01

The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.). The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB) and ∼90% (RSLB). The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2), about 49%, and the oleic monounsaturated (18  :  1), ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3), ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

Terahertz absorption in graphite nanoplatelets/polylactic acid composites

NASA Astrophysics Data System (ADS)

Bychanok, D.; Angelova, P.; Paddubskaya, A.; Meisak, D.; Shashkova, L.; Demidenko, M.; Plyushch, A.; Ivanov, E.; Krastev, R.; Kotsilkova, R.; Ogrin, F. Y.; Kuzhir, P.

2018-04-01

The electromagnetic properties of composite materials based on poly(lactic) acid (PLA) filled with graphite nanoplatelets (GNP) were investigated in the microwave (26–37 GHz) and terahertz (0.2–1 THz) frequency ranges. The maximum of the imaginary part of the dielectric permittivity was observed close to 0.6 THz for composites with 1.5 and 3 wt.% of GNP. The experimental data of complex dielectric permittivity of GNP/PLA composites was modelled using the Maxwell-Garnett theory. The effects of fine dispersion, agglomeration, and percolation in GNP-based composites on its electromagnetic constitutive parameters, presence, and position of THz absorption peak are discussed on the basis of the modeling results and experimental data. The unique combination of conductive and geometrical parameters of GNP embedded into the PLA matrix below the percolation threshold allow us to obtain the THz-absorptive material, which may be effectively used as a 3D-printing filament.

Effects of Radiative Emission and Absorption on the Propagation and Extinction of Premixed Gas Flames

NASA Technical Reports Server (NTRS)

Ju, Yiguang; Masuya, Goro; Ronney, Paul D.

1998-01-01

Premixed gas flames in mixtures of CH4, O2, N2, and CO2 were studied numerically using detailed chemical and radiative emission-absorption models to establish the conditions for which radiatively induced extinction limits may exist independent of the system dimensions. It was found that reabsorption of emitted radiation led to substantially higher burning velocities and wider extinction limits than calculations using optically thin radiation models, particularly when CO2, a strong absorber, is present in the unburned gas, Two heat loss mechanisms that lead to flammability limits even with reabsorption were identified. One is that for dry hydrocarbon-air mixtures, because of the differences in the absorption spectra of H2O and CO2, most of the radiation from product H2O that is emitted in the upstream direction cannot be absorbed by the reactants. The second is that the emission spectrum Of CO2 is broader at flame temperatures than ambient temperature: thus, some radiation emitted near the flame front cannot be absorbed by the reactants even when they are seeded with CO2 Via both mechanisms, some net upstream heat loss due to radiation will always occur, leading to extinction of sufficiently weak mixtures. Downstream loss has practically no influence. Comparison with experiment demonstrates the importance of reabsorption in CO2 diluted mixtures. It is concluded that fundamental flammability limits can exist due to radiative heat loss, but these limits are strongly dependent on the emission-absorption spectra of the reactant and product -gases and their temperature dependence and cannot be predicted using gray-gas or optically thin model parameters. Applications to practical flames at high pressure, in large combustion chambers, and with exhaust-gas or flue-gas recirculation are discussed.

Reactor for tracking catalyst nanoparticles in liquid at high temperature under a high-pressure gas phase with X-ray absorption spectroscopy.

PubMed

Nguyen, Luan; Tao, Franklin Feng

2018-02-01

Structure of catalyst nanoparticles dispersed in liquid phase at high temperature under gas phase of reactant(s) at higher pressure (≥5 bars) is important for fundamental understanding of catalytic reactions performed on these catalyst nanoparticles. Most structural characterizations of a catalyst performing catalysis in liquid at high temperature under gas phase at high pressure were performed in an ex situ condition in terms of characterizations before or after catalysis since, from technical point of view, access to the catalyst nanoparticles during catalysis in liquid phase at high temperature under high pressure reactant gas is challenging. Here we designed a reactor which allows us to perform structural characterization using X-ray absorption spectroscopy including X-ray absorption near edge structure spectroscopy and extended X-ray absorption fine structure spectroscopy to study catalyst nanoparticles under harsh catalysis conditions in terms of liquid up to 350 °C under gas phase with a pressure up to 50 bars. This reactor remains nanoparticles of a catalyst homogeneously dispersed in liquid during catalysis and X-ray absorption spectroscopy characterization.

Kinetic study of carbon dioxide absorption into glycine promoted diethanolamine (DEA)

NASA Astrophysics Data System (ADS)

Pudjiastuti, Lily; Susianto, Altway, Ali; IC, Maria Hestia; Arsi, Kartika

2015-12-01

In industry, especially petrochemical, oil and natural gas industry, required separation process of CO2 gas which is a corrosive gas (acid gas). This characteristic can damage the plant utility and piping systems as well as reducing the caloric value of natural gas. Corrosive characteristic of CO2 will appear in areas where there is a decrease in temperature and pressure, such as at the elbow pipe, tubing, cooler and injector turbine. From disadvantages as described above, then it is important to do separation process in the CO2 gas stream, one of the method for remove CO2 from the gas stream is reactive absorption using alkanolamine based solution with promotor. Therefore, this study is done to determine the kinetics constant of CO2 absorption in diethanolamine (DEA) solution using a glycine promoter. Glycine is chosen as a promoter because glycine is a primary amine compound which is reactive, moreover, glycine has resistance to high temperatures so it will not easy to degradable and suitable for application in industry. The method used in this study is absorption using laboratory scale wetted wall column equipment at atmospheric of pressure. This study will to provide the reaction kinetics data information in order to optimize the separation process of CO2 in the industrialized world. The experimental results show that rising temperatures from 303,15 - 328,15 K and the increase of concentration of glycine from 1% - 3% weight will increase the absorption rate of carbon dioxide in DEA promoted with glycine by 24,2% and 59,764% respectively, also the reaction kinetic constant is 1.419 × 1012 exp (-3634/T) (m3/kmol.s). This result show that the addition of glycine as a promoter can increase absorption rate of carbon dioxide in diethanolamine solution and cover the weaknesses of diethanolamine solution.

The absorption of protons with specific amino acids and carbohydrates by yeast

PubMed Central

Seaston, A.; Inkson, C.; Eddy, A. A.

1973-01-01

1. Proton uptake in the presence of various amino acids was studied in washed yeast suspensions containing deoxyglucose and antimycin to inhibit energy metabolism. A series of mutant strains of Saccharomyces cerevisiae with defective amino acid permeases was used. The fast absorption of glycine, l-citrulline and l-methionine through the general amino acid permease was associated with the uptake of about 2 extra equivalents of protons per mol of amino acid absorbed, whereas the slower absorption of l-methionine, l-proline and, possibly, l-arginine through their specific permeases was associated with about 1 proton equivalent. l-Canavanine and l-lysine were also absorbed with 1–2 equivalents of protons. 2. A strain of Saccharomyces carlsbergensis behaved similarly with these amino acids. 3. Preparations of the latter yeast grown with maltose subsequently absorbed it with 2–3 equivalents of protons. The accelerated rate of proton uptake increased up to a maximum value with the maltose concentration (Km=1.6mm). The uptake of protons was also faster in the presence of α-methylglucoside and sucrose, but not in the presence of glucose, galactose or 2-deoxyglucose. All of these compounds except the last could cause acid formation. The uptake of protons induced by maltose, α-methylglucoside and sucrose was not observed when the yeast was grown with glucose, although acid was then formed both from sucrose and glucose. 4. A strain of Saccharomyces fragilis that both fermented and formed acid from lactose absorbed extra protons in the presence of lactose. 5. The observations show that protons were co-substrates in the systems transporting the amino acids and certain of the carbohydrates. PMID:4587071

Primary gas thermometry by means of laser-absorption spectroscopy: determination of the Boltzmann constant.

PubMed

Casa, G; Castrillo, A; Galzerano, G; Wehr, R; Merlone, A; Di Serafino, D; Laporta, P; Gianfrani, L

2008-05-23

We report on a new optical implementation of primary gas thermometry based on laser-absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) nu1+2nu2(0)+nu3 transition in CO2 gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of approximately 1.6 x 10(-4).

Primary Gas Thermometry by Means of Laser-Absorption Spectroscopy: Determination of the Boltzmann Constant

NASA Astrophysics Data System (ADS)

Casa, G.; Castrillo, A.; Galzerano, G.; Wehr, R.; Merlone, A.; di Serafino, D.; Laporta, P.; Gianfrani, L.

2008-05-01

We report on a new optical implementation of primary gas thermometry based on laser-absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) ν1+2ν20+ν3 transition in CO2 gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of ˜1.6×10-4.

In vivo percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in humans: a summary.

PubMed

Wester, R C; Hui, X; Maibach, H I; Bell, K; Schell, M J; Northington, D J; Strong, P; Culver, B D

1998-01-01

Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry, which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10% in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percent dose, with flux and permeability constant (Kp) calculated at 0.009 microg/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percent dose, with flux and Kp calculated at 0.009 microg/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percent, with flux and Kp calculated at 0.01 microg/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

Far-ultraviolet absorption spectra of quasars: How to find missing hot gas and metals

NASA Technical Reports Server (NTRS)

Verner, D. A.; Tytler, David; Barthel, P. D.

1994-01-01

We show that some high-redshift QSO absorption systems that reveal only the H I Lyman series lines at wavelengths visible from the ground maybe a new class of ultra-high-ionization metal line systems, with metal lines in the far-UV region which is now being explored with satellites. At high temperatures or in intense radiation fields metal systems will not show the usual C IV absorption, and O VI will become the most prominent metal absorber. At still higher ionization, O IV also becomes weak and the strongest metal lines are from Ne VIII, Mg X and Si XII, which have doublets in the rangs 500-800 A. Hence very high ionization metal systems will not show metal lines in existing spectra. Recent X-ray observations show that galaxy halos contain hot gas, so we predict that far-UV spectra of QSOs will also show this gas.

Carbon Dioxide Absorption by the Imidazolium-Amino Acid Ionic Liquids, Kinetics, and Mechanism Approach.

PubMed

Rezaeian, Mojtaba; Izadyar, Mohammad; Nakhaei Pour, Ali

2018-06-25

The kinetics and mechanism of CO 2 absorption by ionic liquids (ILs) were studied, theoretically. The studied ILs are composed of 1-ethyl-3-methylimidazolium [Emim] + as the cation with a general formula of the [Emim][X] (X = Gly - , Ala - , Lys - , Arg - ). To investigate the alkyl chain length and the number of the amine group effects on the CO 2 absorption, different amino acid anions were chosen. On the basis of the enthalpy changes during CO 2 capture, a chemisorption nature is confirmed. An increase in the number of amine (-NH 2 ) groups in the ILs structures, facilitates the CO 2 absorption. According to kinetic results, the rate of CO 2 absorption by [Emim][Gly] is higher than that of [Emim][Ala]. This can be interpreted by a higher steric hindrance in [Emim][Ala] due to an additional methyl group in the amino acid chain. Donor-acceptor interactions and C-N bond formation were investigated by natural bond orbital analysis. Moreover, topological studies show a covalent nature for the C-N bond critical point that showing CO 2 capture is a chemisorption process. Finally, on the basis of kinetic energy results, donor-acceptor interaction and topological analysis, [Emim][Arg] is proposed as the best candidate for CO 2 absorption from the kinetic and thermodynamic viewpoints.

Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature

PubMed Central

Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

2016-01-01

Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons. PMID:26892255

Near-infrared incoherent broadband cavity enhanced absorption spectroscopy (NIR-IBBCEAS) for detection and quantification of natural gas components.

PubMed

Prakash, Neeraj; Ramachandran, Arun; Varma, Ravi; Chen, Jun; Mazzoleni, Claudio; Du, Ke

2018-06-28

The principle of near-infrared incoherent broadband cavity enhanced absorption spectroscopy was employed to develop a novel instrument for detecting natural gas leaks as well as for testing the quality of natural gas mixtures. The instrument utilizes the absorption features of methane, butane, ethane, and propane in the wavelength region of 1100 nm to 1250 nm. The absorption cross-section spectrum in this region for methane was adopted from the HITRAN database, and those for the other three gases were measured in the laboratory. A singular-value decomposition (SVD) based analysis scheme was employed for quantifying methane, butane, ethane, and propane by performing a linear least-square fit. The developed instrument achieved a detection limit of 460 ppm, 141 ppm, 175 ppm and 173 ppm for methane, butane, ethane, and propane, respectively, with a measurement time of 1 second and a cavity length of 0.59 m. These detection limits are less than 1% of the Lower Explosive Limit (LEL) for each gas. The sensitivity can be further enhanced by changing the experimental parameters (such as cavity length, lamp power etc.) and using longer averaging intervals. The detection system is a low-cost and portable instrument suitable for performing field monitorings. The results obtained on the gas mixture emphasize the instrument's potential for deployment at industrial facilities dealing with natural gas, where potential leaks pose a threat to public safety.

Probing the extent and content of low ionization gas in galaxies: QSO absorption and HI emission

NASA Technical Reports Server (NTRS)

Womble, Donna S.

1993-01-01

The small projected separations of some QSO's and low-redshift galaxies provide unique opportunities to study the extent and content of gas in galaxies through observation of absorption in the QSO spectra. Observations of these systems provide valuable information on the connection between the absorbing gas and the galaxy, as well as detailed information on the morphology and environment of the galaxy itself. While there is direct evidence that galaxies can produce the intervening-type QSO absorption lines, over the past decade, the study of such 'QSO-galaxy pairs' (at low redshift) has been considered unsuccessful because new detections of absorption were seldom made. A fundamental problem concerning the relation between these low-redshift systems and those seen at moderate to high redshift remains unresolved. Direct and indirect measures of galaxy absorption cross sections at moderate to high redshifts (z is approximately greater than 20.5) are much larger than the optical and HI sizes of local galaxies. However, direct comparison of the low and moderate to high redshift systems is difficult since different ions are observed in different redshift regimes. Observations are presented for a new sample of QSO-galaxy pairs. Nine new QSO's which shine through nearby galaxies (on the sky-plane) were observed to search for CaII absorption in the QSO spectra at the foreground galaxy redshifts.

Effective optical path length for tandem diffuse cubic cavities as gas absorption cell

NASA Astrophysics Data System (ADS)

Yu, J.; Gao, Q.; Zhang, Y. G.; Zhang, Z. G.; Wu, S. H.

2014-12-01

Tandem diffuse cubic cavities designed by connecting two single diffuse cubic-shaped cavities, A and B, with an aperture (port fraction fap) in the middle of the connecting baffle was developed as a gas absorption cell. The effective optical path length (EOPL) was evaluated by comparing the oxygen absorption signal in the cavity and in air based on tunable diode laser absorption spectroscopy (TDLAS). Experimental results manifested an enhancement of EOPL for the tandem diffuse cubic cavities as the decrease of fap and can be expressed as the sum of EOPL of two single cubic cavities at fap < 0.01, which coincided well with theoretical analysis. The simulating EOPL was smaller than experimental results at fap > 0.01, which indicated that back scattering light from cavity B to cavity A cannot be ignored at this condition.

Acid gas scrubbing by composite solvent-swollen membranes

DOEpatents

Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

1988-01-01

A composite immobilized liquid membrane suitable for acid gas scrubbing is disclosed. The membrane is a solvent-swollen polymer and a microporous polymeric support, the solvent being selected from a class of highly polar solvents containing at least one atom selected from nitrogen, oxygen, phosphorous and sulfur, and having a boiling point of at least 100.degree. C. and a solubility parameter of from about 7.5 to about 13.5 (cal/cm.sup.3 -atm).sup.1/2. Such solvents are homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. Also disclosed are methods of acid gas scrubbing of high- and low-Btu gas effluents with such solvent-swollen membranes.

Acid gas scrubbing by composite solvent-swollen membranes

DOEpatents

Matson, S.L.; Lee, E.K.L.; Friesen, D.T.; Kelly, D.J.

1988-04-12

A composite immobilized liquid membrane suitable for acid gas scrubbing is disclosed. The membrane is a solvent-swollen polymer and a microporous polymeric support, the solvent being selected from a class of highly polar solvents containing at least one atom selected from nitrogen, oxygen, phosphorus and sulfur, and having a boiling point of at least 100 C and a solubility parameter of from about 7.5 to about 13.5 (cal/cm[sup 3]-atm)[sup 1/2]. Such solvents are homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. Also disclosed are methods of acid gas scrubbing of high- and low-Btu gas effluents with such solvent-swollen membranes. 3 figs.

Effects of an acidic beverage (Coca-Cola) on absorption of ketoconazole.

PubMed Central

Chin, T W; Loeb, M; Fong, I W

1995-01-01

Absorption of ketoconazole is impaired in patients with achlorhydria. The purpose of this study was to determine the effectiveness of a palatable acidic beverage (Coca-Cola Classic, pH 2.5) in improving the absorption of ketoconazole in the presence of drug-induced achlorhydria. A prospective, randomized, three-way crossover design with a 1-week wash-out period between each treatment was employed. Nine healthy nonsmoking, nonobese volunteers between 22 and 41 years old were studied. Each subject was randomized to receive three treatments: (A) ketoconazole 200-mg tablet with water (control), (B) omeprazole (60 mg) followed by ketoconazole (200 mg) taken with water, and (C) omeprazole (60 mg) followed by ketoconazole (200 mg) taken with 240 ml of Coca-Cola Classic. The pH values of gastric aspirates were checked after omeprazole was administered to confirm attainment of a pH of > 6. Multiple serum samples were obtained for measurements of ketoconazole concentrations by high-pressure liquid chromatography. The mean area under the ketoconazole concentration-time curve from zero to infinity for the control treatment (17.9 +/- 13.1 mg.h/liter) was significantly greater than that for treatment B (3.5 +/- 5.1 mg.h/liter; 16.6% +/- 15.0% of control). The mean peak concentration was highest for the control treatment (4.1 +/- 1.9 micrograms/ml), for which the mean peak concentration showed a significant increase over that for treatment B. The absorption of ketoconazole was reduced in the presence of omeprazole-induced achlorhydria. However, drug absorption was significantly increased, to approximately 65% of the mean for the control treatment, when the drug was taken with an acidic beverage, such as Coca-Cola. PMID:7486898

ISX is a retinoic acid-sensitive gatekeeper that controls intestinal β,β-carotene absorption and vitamin A production

PubMed Central

Lobo, Glenn P.; Hessel, Susanne; Eichinger, Anne; Noy, Noa; Moise, Alexander R.; Wyss, Adrian; Palczewski, Krzysztof; von Lintig, Johannes

2010-01-01

The uptake of dietary lipids from the small intestine is a complex process that depends on the activities of specific membrane receptors with yet unknown regulatory mechanisms. Using both mouse models and human cell lines, we show here that intestinal lipid absorption by the scavenger receptor class B type 1 (SR-BI) is subject to control by retinoid signaling. Retinoic acid via retinoic acid receptors induced expression of the intestinal transcription factor ISX. ISX then repressed the expression of SR-B1 and the carotenoid-15,15′-oxygenase Bcmo1. BCMO1 acts downstream of SR-BI and converts absorbed β,β-carotene to the retinoic acid precursor, retinaldehyde. Using BCMO1-knockout mice, we demonstrated increased intestinal SR-BI expression and systemic β,β-carotene accumulation. SR-BI-dependent accumulation of β,β-carotene was prevented by dietary retinoids that induced ISX expression. Thus, our study revealed a diet-responsive regulatory network that controls β,β-carotene absorption and vitamin A production by negative feedback regulation. The role of SR-BI in the intestinal absorption of other dietary lipids, including cholesterol, fatty acids, and tocopherols, implicates retinoid signaling in the regulation of lipid absorption more generally and has clinical implications for diseases associated with dyslipidemia.—Lobo, G. P., Hessel, S., Eichinger, A., Noy, N., Moise, A. R., Wyss, A., Palczewski, K., von Lintig, J. ISX is a retinoic acid-sensitive gatekeeper that controls intestinal β,β-carotene absorption and vitamin A production. PMID:20061533

The Clean Coal Technology Program 100 MWe demonstration of gas suspension absorption for flue gas desulfurization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, F.E.; Hedenhag, J.G.; Marchant, S.K.

1997-12-31

AirPol Inc., with the cooperation of the Tennessee Valley Authority (TVA) under a Cooperative Agreement with the United States Department of Energy, installed and tested a 10 MWe Gas Suspension Absorption (GSA) Demonstration system at TVA`s Shawnee Fossil Plant near Paducah, Kentucky. This low-cost retrofit project demonstrated that the GSA system can remove more than 90% of the sulfur dioxide from high-sulfur coal-fired flue gas, while achieving a relatively high utilization of reagent lime. This paper presents a detailed technical description of the Clean Coal Technology demonstration project. Test results and data analysis from the preliminary testing, factorial tests, airmore » toxics texts, 28-day continuous demonstration run of GSA/electrostatic precipitator (ESP), and 14-day continuous demonstration run of GSA/pulse jet baghouse (PJBH) are also discussed within this paper.« less

An Experimental and Computational Study of the Gas-Phase Acidities of the Common Amino Acid Amides.

PubMed

Plummer, Chelsea E; Stover, Michele L; Bokatzian, Samantha S; Davis, John T M; Dixon, David A; Cassady, Carolyn J

2015-07-30

Using proton-transfer reactions in a Fourier transform ion cyclotron resonance mass spectrometer and correlated molecular orbital theory at the G3(MP2) level, gas-phase acidities (GAs) and the associated structures for amides corresponding to the common amino acids have been determined for the first time. These values are important because amino acid amides are models for residues in peptides and proteins. For compounds whose most acidic site is the C-terminal amide nitrogen, two ions populations were observed experimentally with GAs that differ by 4-7 kcal/mol. The lower energy, more acidic structure accounts for the majority of the ions formed by electrospray ionization. G3(MP2) calculations predict that the lowest energy anionic conformer has a cis-like orientation of the [-C(═O)NH](-) group whereas the higher energy, less acidic conformer has a trans-like orientation of this group. These two distinct conformers were predicted for compounds with aliphatic, amide, basic, hydroxyl, and thioether side chains. For the most acidic amino acid amides (tyrosine, cysteine, tryptophan, histidine, aspartic acid, and glutamic acid amides) only one conformer was observed experimentally, and its experimental GA correlates with the theoretical GA related to side chain deprotonation.

Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

NASA Technical Reports Server (NTRS)

May, R. D.; Molina, L. T.; Webster, C. R.

1988-01-01

A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

Simultaneous high-speed gas property measurements at the exhaust gas recirculation cooler exit and at the turbocharger inlet of a multicylinder diesel engine using diode-laser-absorption spectroscopy.

PubMed

Jatana, Gurneesh S; Magee, Mark; Fain, David; Naik, Sameer V; Shaver, Gregory M; Lucht, Robert P

2015-02-10

A diode-laser-absorption-spectroscopy-based sensor system was used to perform high-speed (100 Hz to 5 kHz) measurements of gas properties (temperature, pressure, and H(2)O vapor concentration) at the turbocharger inlet and at the exhaust gas recirculation (EGR) cooler exit of a diesel engine. An earlier version of this system was previously used for high-speed measurements of gas temperature and H(2)O vapor concentration in the intake manifold of the diesel engine. A 1387.2 N m tunable distributed feedback diode laser was used to scan across multiple H(2)O absorption transitions, and the direct absorption signal was recorded using a high-speed data acquisition system. Compact optical connectors were designed to conduct simultaneous measurements in the intake manifold, the EGR cooler exit, and the turbocharger inlet of the engine. For measurements at the turbocharger inlet, these custom optical connectors survived gas temperatures as high as 800 K using a simple and passive arrangement in which the temperature-sensitive components were protected from high temperatures using ceramic insulators. This arrangement reduced system cost and complexity by eliminating the need for any active water or oil cooling. Diode-laser measurements performed during steady-state engine operation were within 5% of the thermocouple and pressure sensor measurements, and within 10% of the H(2)O concentration values derived from the CO(2) gas analyzer measurements. Measurements were also performed in the engine during transient events. In one such transient event, where a step change in fueling was introduced, the diode-laser sensor was able to capture the 30 ms change in the gas properties; the thermocouple, on the other hand, required 7.4 s to accurately reflect the change in gas conditions, while the gas analyzer required nearly 600 ms. To the best of our knowledge, this is the first implementation of such a simple and passive arrangement of high-temperature optical connectors as well

A lactic acid-fermented oat gruel increases non-haem iron absorption from a phytate-rich meal in healthy women of childbearing age.

PubMed

Bering, Stine; Suchdev, Seema; Sjøltov, Laila; Berggren, Anna; Tetens, Inge; Bukhave, Klaus

2006-07-01

Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, and formation of soluble complexes of Fe and organic acids. We tested the effect of an oat gruel fermented with Lactobacillus plantarum 299v on non-haem Fe absorption from a low-Fe bioavailability meal compared with a pasteurised, fermented oat gruel and non-fermented oat gruels. In a cross-over trial twenty-four healthy women with a mean age of 25 (sd 4) years were served (A) fermented gruel, (B) pasteurised fermented gruel, (C) pH-adjusted non-fermented gruel, and (D) non-fermented gruel with added organic acids. The meals were extrinsically labelled with 55Fe or 59Fe and consumed on 4 consecutive days, for example, in the order ABBA or BAAB followed by CDDC or DCCD in a second period. Fe absorption was determined from isotope activities in blood samples. The fermented gruel with live L. plantarum 299v increased Fe absorption significantly (P < 0.0001) compared with the pasteurised and non-fermented gruels. The lactic acid concentration in the fermented gruel was 19 % higher than in the pasteurised gruel, but the Fe absorption was increased by 50 %. In the gruel with organic acids, the lactic acid concentration was 52 % lower than in the pasteurised gruel, with no difference in Fe absorption. The fermented gruel increased non-haem Fe absorption from a phytate-rich meal in young women, indicating a specific effect of live L. plantarum 299v and not only an effect of the organic acids.

In vivo percutaneous absorption of boric acid, borax, and disodium octaborate tetrahydrate in humans compared to in vitro absorption in human skin from infinite and finite doses.

PubMed

Wester, R C; Hui, X; Hartway, T; Maibach, H I; Bell, K; Schell, M J; Northington, D J; Strong, P; Culver, B D

1998-09-01

Literature from the first half of this century report concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10%, in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percentage dose, with flux and permeability constant (Kp) calculated at 0.009 microgram/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percentage of dose, with flux and Kp calculated at 0.009 microgram/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percentage, with flux and Kp calculated at 0.01 microgram/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. In vitro human skin percentage of doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 micrograms/cm2/h and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05, 0.5, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microliters/cm2 volume. At 2 microliters/cm2 (the in vivo dosing volume), flux decreased some

Thermal Pressure in Diffuse H2 Gas Measured by Herschel [C II] Emission and FUSE UV H2 Absorption

NASA Astrophysics Data System (ADS)

Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.

2017-04-01

UV absorption studies with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite have made important observations of H2 molecular gas in Galactic interstellar translucent and diffuse clouds. Observations of the 158 μm [C II] fine-structure line with Herschel trace the same H2 molecular gas in emission. We present [C II] observations along 27 lines of sight (LOSs) toward target stars of which 25 have FUSE H2 UV absorption. Two stars have only HST STIS C II λ2325 absorption data. We detect [C II] 158 μm emission features in all but one target LOS. For three target LOSs that are close to the Galactic plane, | {\\text{}}b| < 1°, we also present position-velocity maps of [C II] emission observed by Herschel Heterodyne Instrument in the Far Infrared (HIFI) in on-the-fly spectral-line mapping. We use the velocity-resolved [C II] spectra observed by the HIFI instrument toward the target LOSs observed by FUSE to identify [C II] velocity components associated with the H2 clouds. We analyze the observed velocity integrated [C II] spectral-line intensities in terms of the densities and thermal pressures in the H2 gas using the H2 column densities and temperatures measured by the UV absorption data. We present the H2 gas densities and thermal pressures for 26 target LOSs and from the [C II] intensities derive a mean thermal pressure in the range of ˜6100-7700 K cm-3 in diffuse H2 clouds. We discuss the thermal pressures and densities toward 14 targets, comparing them to results obtained using the UV absorption data for two other tracers C I and CO. Our results demonstrate the richness of the far-IR [C II] spectral data which is a valuable complement to the UV H2 absorption data for studying diffuse H2 molecular clouds. While the UV absorption is restricted to the directions of the target star, far-IR [C II] line emission offers an opportunity to employ velocity-resolved spectral-line mapping capability to study in detail the clouds’ spatial and velocity structures.

Formaldehyde in Absorption: Tracing Molecular Gas in Early-Type Galaxies

NASA Astrophysics Data System (ADS)

Dollhopf, Niklaus M.; Donovan Meyer, Jennifer

2016-01-01

Early-Type Galaxies (ETGs) have been long-classified as the red, ellipsoidal branch of the classic Hubble tuning fork diagram of galactic structure. In part with this classification, ETGs are thought to be molecular and atomic gas-poor with little to no recent star formation. However, recent efforts have questioned this ingrained classification. Most notably, the ATLAS3D survey of 260 ETGs within ~40 Mpc found 22% contain CO, a common tracer for molecular gas. The presence of cold molecular gas also implies the possibility for current star formation within these galaxies. Simulations do not accurately predict the recent observations and further studies are necessary to understand the mechanisms of ETGs.CO traces molecular gas starting at densities of ~102 cm-3, which makes it a good tracer of bulk molecular gas, but does little to constrain the possible locations of star formation within the cores of dense molecular gas clouds. Formaldehyde (H2CO) traces molecular gas on the order of ~104 cm-3, providing a further constraint on the location of star-forming gas, while being simple enough to possibly be abundant in gas-poor ETGs. In cold molecular clouds at or above ~104 cm-3 densities, the structure of formaldehyde enables a phenomenon in which rotational transitions have excitation temperatures driven below the temperature of the cosmic microwave background (CMB), ~2.7 K. Because the CMB radiates isotropically, formaldehyde can be observed in absorption, independent of distance, as a tracer of moderately-dense molecular clouds and star formation.This novel observation technique of formaldehyde was incorporated for observations of twelve CO-detected ETGs from the ATLAS3D sample, including NGC 4710 and PGC 8815, to investigate the presence of cold molecular gas, and possible star formation, in ETGs. We present images from the Very Large Array, used in its C-array configuration, of the J = 11,0 - 11,1 transition of formaldehyde towards these sources. We report our

Molecular dynamics simulations of classical sound absorption in a monatomic gas

NASA Astrophysics Data System (ADS)

Ayub, M.; Zander, A. C.; Huang, D. M.; Cazzolato, B. S.; Howard, C. Q.

2018-05-01

Sound wave propagation in argon gas is simulated using molecular dynamics (MD) in order to determine the attenuation of acoustic energy due to classical (viscous and thermal) losses at high frequencies. In addition, a method is described to estimate attenuation of acoustic energy using the thermodynamic concept of exergy. The results are compared against standing wave theory and the predictions of the theory of continuum mechanics. Acoustic energy losses are studied by evaluating various attenuation parameters and by comparing the changes in behavior at three different frequencies. This study demonstrates acoustic absorption effects in a gas simulated in a thermostatted molecular simulation and quantifies the classical losses in terms of the sound attenuation constant. The approach can be extended to further understanding of acoustic loss mechanisms in the presence of nanoscale porous materials in the simulation domain.

Absorption of thiamine and nicotinic acid in the rat intestine during fasting and immobilization stress

NASA Technical Reports Server (NTRS)

Kirilyuk, O. G.; Khmelevskiy, Y. V.

1980-01-01

By perfusion of isolated sections of intestine with a solution containing thiamine at a concentration of 3.1 micromole, it was established that thiamine absorption in animals fasted for 72 hours decreased by 28 percent, whereas absorption increased by 12 percent in rats after 24 hour immobilization. After immobilization, absorption of label in the intestinal mucosa increased. Na K ATPase activity in the intestinal mucosa decreased by 10 percent during fasting, and it increased with immobilization of the animals. Activity of Na K ATPase in the intestinal mucosa cells determined the absorption rate of thiamine and nicotinic acid at the level of vitamin transport through the plasma membranes of the enterocytes.

Mass energy-absorption coefficients and average atomic energy-absorption cross-sections for amino acids in the energy range 0.122-1.330 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

More, Chaitali V., E-mail: chaitalimore89@gmail.com; Lokhande, Rajkumar M.; Pawar, Pravina P., E-mail: pravinapawar4@gmail.com

Mass attenuation coefficients of amino acids such as n-acetyl-l-tryptophan, n-acetyl-l-tyrosine and d-tryptophan were measured in the energy range 0.122-1.330 MeV. NaI (Tl) scintillation detection system was used to detect gamma rays with a resolution of 8.2% at 0.662 MeV. The measured attenuation coefficient values were then used to determine the mass energy-absorption coefficients (σ{sub a,en}) and average atomic energy-absorption cross sections (μ{sub en}/ρ) of the amino acids. Theoretical values were calculated based on XCOM data. Theoretical and experimental values are found to be in good agreement.

Formation of itraconazole-succinic acid cocrystals by gas antisolvent cocrystallization.

PubMed

Ober, Courtney A; Gupta, Ram B

2012-12-01

Cocrystals of itraconazole, an antifungal drug with poor bioavailability, and succinic acid, a water-soluble dicarboxylic acid, were formed by gas antisolvent (GAS) cocrystallization using pressurized CO(2) to improve itraconazole dissolution. In this study, itraconazole and succinic acid were simultaneously dissolved in a liquid solvent, tetrahydrofuran, at ambient conditions. The solution was then pressurized with CO(2), which decreased the solvating power of tetrahydrofuran and caused crystallization of itraconazole-succinic acid cocrystals. The cocrystals prepared by GAS cocrystallization were compared to those produced using a traditional liquid antisolvent, n-heptane, for crystallinity, chemical structure, thermal behavior, size and surface morphology, potential clinical relevance, and stability. Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy analyses showed that itraconazole-succinic acid cocrystals with physical and chemical properties similar to cocrystals produced using a traditional liquid antisolvent technique can be prepared by CO(2) antisolvent cocrystallization. The dissolution profile of itraconazole was significantly enhanced through GAS cocrystallization with succinic acid, achieving over 90% dissolution in less than 2 h. The cocrystals appeared stable against thermal stress for up to 4 weeks under accelerated stability conditions, showing only moderate decreases in their degree of crystallinity but no change in their crystalline structure. This study shows the utility of an itraconazole-succinic acid cocrystal for improving itraconazole bioavailability while also demonstrating the potential for CO(2) to replace traditional liquid antisolvents in cocrystal preparation, thus making cocrystal production more environmentally benign and scale-up more feasible.

BENCH-SCALE EVALUATION OF CALCIUM SORBENTS FOR ACID GAS EMISSION CONTROL

EPA Science Inventory

Calcium sorbents for acid gas emission control were evaluated for effectiveness in removing SO2/HCl and SO2/NO from simulated incinerator and boiler flue gases. All tests were conducted in a bench-scale reactor (fixed-bed) simulating fabric filter conditions in an acid gas remova...

Ca2+-driven intestinal HCO(3)(-) secretion and CaCO3 precipitation in the European flounder in vivo: influences on acid-base regulation and blood gas transport.

PubMed

Cooper, Christopher A; Whittamore, Jonathan M; Wilson, Rod W

2010-04-01

Marine teleost fish continuously ingest seawater to prevent dehydration and their intestines absorb fluid by mechanisms linked to three separate driving forces: 1) cotransport of NaCl from the gut fluid; 2) bicarbonate (HCO(3)(-)) secretion and Cl(-) absorption via Cl(-)/HCO(3)(-) exchange fueled by metabolic CO(2); and 3) alkaline precipitation of Ca(2+) as insoluble CaCO(3), which aids H(2)O absorption). The latter two processes involve high rates of epithelial HCO(3)(-) secretion stimulated by intestinal Ca(2+) and can drive a major portion of water absorption. At higher salinities and ambient Ca(2+) concentrations the osmoregulatory role of intestinal HCO(3)(-) secretion is amplified, but this has repercussions for other physiological processes, in particular, respiratory gas transport (as it is fueled by metabolic CO(2)) and acid-base regulation (as intestinal cells must export H(+) into the blood to balance apical HCO(3)(-) secretion). The flounder intestine was perfused in vivo with salines containing 10, 40, or 90 mM Ca(2+). Increasing the luminal Ca(2+) concentration caused a large elevation in intestinal HCO(3)(-) production and excretion. Additionally, blood pH decreased (-0.13 pH units) and plasma partial pressure of CO(2) (Pco(2)) levels were elevated (+1.16 mmHg) at the highest Ca perfusate level after 3 days of perfusion. Increasing the perfusate [Ca(2+)] also produced proportional increases in net acid excretion via the gills. When the net intestinal flux of all ions across the intestine was calculated, there was a greater absorption of anions than cations. This missing cation flux was assumed to be protons, which vary with an almost 1:1 relationship with net acid excretion via the gill. This study illustrates the intimate link between intestinal HCO(3)(-) production and osmoregulation with acid-base balance and respiratory gas exchange and the specific controlling role of ingested Ca(2+) independent of any other ion or overall osmolality in marine

Echinococcus granulosus: absorption of cycloleucine and alpha-aminoisobutyric acid by protoscoleces.

PubMed

Jeffs, S A; Arme, C

1986-02-01

Protoscoleces of Echinococcus granulosus absorb the amino acids cycloleucine and alpha-aminoisobutyric acid (AIB) by a combination of mediated uptake and diffusion. After correcting for the latter, values for Kt and Vmax of 0.124 mM and 0.947 nmoles/mg protein/2 min for cycloleucine were calculated; corresponding values for AIB were 0.039 mM and 0.139 nmoles/mg protein/2 min. Both amino acids were accumulated against a concentration gradient and a comparison of Kt and Ki values determined in mutual inhibition experiments suggested that both cycloleucine and AIB share a common uptake locus (loci). Cycloleucine uptake was pH-dependent and could be inhibited by a variety of other amino acids. Neither D- nor L-proline inhibited cycloleucine absorption but D-methionine, D-alanine, D-leucine, D-valine and D-serine were much more effective inhibitors than their L-counterparts.

Techno-economic Analysis of Acid Gas Removal and Liquefaction for Pressurized LNG

NASA Astrophysics Data System (ADS)

Lee, S. H.; Seo, Y. K.; Chang, D. J.

2018-05-01

This study estimated the life cycle cost (LCC) of an acid gas removal and a liquefaction processes for Pressurized LNG (PLNG) production and compared the results with the cost of normal LNG production. PLNG is pressurized LNG that is liquefied at a higher pressure and temperature than normal LNG. Due to the high temperature, the energy for liquefaction is reduced. The allowable CO2 concentration in PLNG is increased up to 3 mol% when the product pressure 25 bar. An amine process with 35 wt% of diethanolamine (DEA) aqueous solution and a nitrogen expansion cycle were selected for the acid gas removal and the liquefaction processes, respectively. Two types of CO2 concentration in the feed gas were investigated to analyze their impacts on the acid gas removal unit. When the CO2 concentration was 5 mol%, the acid gas removal unit was required for both LNG and PLNG production. However, the acid gas removal unit was not necessary in PLNG when the concentration was 0.5 mol% and the pressure was higher than 15 bar. The results showed that the LCC of PLNG was reduced by almost 35% relative to that of LNG when the PLNG pressure was higher than 15 bar.

Electron photodetachment from gas phase peptide dianions. Relation with optical absorption properties.

PubMed

Joly, Laure; Antoine, Rodolphe; Broyer, Michel; Lemoine, Jérôme; Dugourd, Philippe

2008-02-07

Electron detachment from peptide dianions is studied as a function of the laser wavelength. The first step for the detachment is a resonant electronic excitation of the dianions. Electronic excitation spectra are reported for three peptides, including gramicidin. A comparative study of the detachment yield for 13 peptides was performed at 260 nm and at 220 nm. At 260 nm, the detachment yield is mainly driven by the sum of the absorption coefficients of the aromatic amino acids that are contained in the peptide. At 220 nm, no direct relation is observed between the electron photodetachement yields and the sum of absorption efficiencies. At this wavelength, the sequence and the structure of the peptide may have an influence on the photodetachment process.

Acid-catalyzed condensed-phase reactions of limonene and terpineol and their impacts on gas-to-particle partitioning in the formation of organic aerosols.

PubMed

Li, Yong Jie; Cheong, Gema Y L; Lau, Arthur P S; Chan, Chak K

2010-07-15

We investigated the condensed-phase reactions of biogenic VOCs with C double bond C bonds (limonene, C(10)H(16), and terpineol, C(10)H(18)O) catalyzed by sulfuric acid by both bulk solution (BS) experiments and gas-particle (GP) experiments using a flow cell reactor. Product analysis by gas chromatography-mass spectrometry (GC-MS) showed that cationic polymerization led to dimeric and trimeric product formation under conditions of relative humidity (RH) <20% (in the GP experiments) and a sulfuric acid concentration of 57.8 wt % (in the BS experiments), while hydration occurred under conditions of RH > 20% (in the GP experiments) and sulfuric acid concentrations of 46.3 wt % or lower (in the BS experiments). Apparent partitioning coefficients (K(p,rxn)) were estimated from the GP experiments by including the reaction products. Only under extremely low RH conditions (RH < 5%) did the values of K(p,rxn) ( approximately 5 x 10(-6) m(3)/microg for limonene and approximately 2 x 10(-5) m(3)/microg for terpineol) substantially exceed the physical partitioning coefficients (K(p) = 6.5 x 10(-8) m(3)/microg for limonene and =2.3 x 10(-6) m(3)/microg for terpineol) derived from the absorptive partitioning theory. At RH higher than 5%, the apparent partitioning coefficients (K(p,rxn)) of both limonene and terpineol were in the same order of magnitude as the K(p) values derived from the absorptive partitioning theory. Compared with other conditions including VOC concentration and degree of neutralization (by ammonium) of acidic particles, RH is a critical parameter that influences both the reaction mechanisms and the uptake ability (K(p,rxn) values) of these processes. The finding suggests that RH needs to be considered when taking the effects of acid-catalyzed reactions into account in estimating organic aerosol formation from C double bond C containing VOCs.

Effect of ursodeoxycholic acid treatment on ileal absorption of bile acids in man as determined by the SeHCAT test.

PubMed

Eusufzai, S; Ericsson, S; Cederlund, T; Einarsson, K; Angelin, B

1991-09-01

The effects of urodeoxycholic acid on ileal absorption of bile acids and on serum bile acid and lipoprotein concentrations were studied. Eight healthy subjects were investigated. The gamma emitting bile acid analogue, SeHCAT, was given orally and its fractional catabolic rate and seven day retention were assessed by repeated external counting over the upper abdomen during the next seven days. Ursodeoxycholic acid was then given orally at a dose of 15 mg/kg/day for three weeks and the study was repeated during treatment. The fractional catabolic rate increased by 64% (mean (SD), 0.333 (0.159) v 0.203 (0.061)/day; p less than 0.05) and seven day retention decreased by 44% (15(10) v 27(10)%, p less than 0.001), indicating bile acid malabsorption. Total serum cholesterol fell from 5.79 (1.22) to 5.50 (1.18) mmol/l (p = 0.05), while serum ursodeoxycholic acid increased 22 fold (7.87 (2.67) v 0.34 (0.24) mumol/l, p less than 0.001). Five of the subjects continued taking 30 mg/kg/day of ursodeoxycholic acid for one week and showed an increase in fractional catabolic rate of 81% (0.300 (0.091) v 0.166 (0.037)/day; p less than 0.05) and a fall in seven day retention of 50% (16 (12) v 32 (8)%, p less than 0.01). There were significant reductions in total cholesterol (5.36 (1.71) v 6.08 (1.47) mmol/l; p less than 0.05) and low density lipoprotein cholesterol (3.70 (1.33) v 4.58 (1.16) mmol/l; p less than 0.05). The results support the concept tht ursodeoxycholic acid treatment interferes with the absorption of endogenous bile acids, and emphasise the beneficial effects of this treatment of lipoprotein concentrations in man.

Effect of ursodeoxycholic acid treatment on ileal absorption of bile acids in man as determined by the SeHCAT test.

PubMed Central

Eusufzai, S; Ericsson, S; Cederlund, T; Einarsson, K; Angelin, B

1991-01-01

The effects of urodeoxycholic acid on ileal absorption of bile acids and on serum bile acid and lipoprotein concentrations were studied. Eight healthy subjects were investigated. The gamma emitting bile acid analogue, SeHCAT, was given orally and its fractional catabolic rate and seven day retention were assessed by repeated external counting over the upper abdomen during the next seven days. Ursodeoxycholic acid was then given orally at a dose of 15 mg/kg/day for three weeks and the study was repeated during treatment. The fractional catabolic rate increased by 64% (mean (SD), 0.333 (0.159) v 0.203 (0.061)/day; p less than 0.05) and seven day retention decreased by 44% (15(10) v 27(10)%, p less than 0.001), indicating bile acid malabsorption. Total serum cholesterol fell from 5.79 (1.22) to 5.50 (1.18) mmol/l (p = 0.05), while serum ursodeoxycholic acid increased 22 fold (7.87 (2.67) v 0.34 (0.24) mumol/l, p less than 0.001). Five of the subjects continued taking 30 mg/kg/day of ursodeoxycholic acid for one week and showed an increase in fractional catabolic rate of 81% (0.300 (0.091) v 0.166 (0.037)/day; p less than 0.05) and a fall in seven day retention of 50% (16 (12) v 32 (8)%, p less than 0.01). There were significant reductions in total cholesterol (5.36 (1.71) v 6.08 (1.47) mmol/l; p less than 0.05) and low density lipoprotein cholesterol (3.70 (1.33) v 4.58 (1.16) mmol/l; p less than 0.05). The results support the concept tht ursodeoxycholic acid treatment interferes with the absorption of endogenous bile acids, and emphasise the beneficial effects of this treatment of lipoprotein concentrations in man. PMID:1916489

Modeling acid-gas generation from boiling chloride brines

PubMed Central

2009-01-01

Background This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Results Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150°C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental data from other studies. Conclusion The combination of reactive transport with multicomponent brine chemistry to study evaporation, boiling, and the potential for acid gas generation at the proposed Yucca Mountain repository is seen as an improvement relative to previously applied simpler batch evaporation models. This approach allows the evaluation of thermal, hydrological, and chemical (THC) processes in a coupled manner, and modeling of settings much more relevant to actual field conditions than the distillation experiment considered. The actual and modeled distillation

Ca2+-driven intestinal HCO3− secretion and CaCO3 precipitation in the European flounder in vivo: influences on acid-base regulation and blood gas transport

PubMed Central

Cooper, Christopher A.; Whittamore, Jonathan M.

2010-01-01

Marine teleost fish continuously ingest seawater to prevent dehydration and their intestines absorb fluid by mechanisms linked to three separate driving forces: 1) cotransport of NaCl from the gut fluid; 2) bicarbonate (HCO3−) secretion and Cl− absorption via Cl−/HCO3− exchange fueled by metabolic CO2; and 3) alkaline precipitation of Ca2+ as insoluble CaCO3, which aids H2O absorption). The latter two processes involve high rates of epithelial HCO3− secretion stimulated by intestinal Ca2+ and can drive a major portion of water absorption. At higher salinities and ambient Ca2+ concentrations the osmoregulatory role of intestinal HCO3− secretion is amplified, but this has repercussions for other physiological processes, in particular, respiratory gas transport (as it is fueled by metabolic CO2) and acid-base regulation (as intestinal cells must export H+ into the blood to balance apical HCO3− secretion). The flounder intestine was perfused in vivo with salines containing 10, 40, or 90 mM Ca2+. Increasing the luminal Ca2+ concentration caused a large elevation in intestinal HCO3− production and excretion. Additionally, blood pH decreased (−0.13 pH units) and plasma partial pressure of CO2 (Pco2) levels were elevated (+1.16 mmHg) at the highest Ca perfusate level after 3 days of perfusion. Increasing the perfusate [Ca2+] also produced proportional increases in net acid excretion via the gills. When the net intestinal flux of all ions across the intestine was calculated, there was a greater absorption of anions than cations. This missing cation flux was assumed to be protons, which vary with an almost 1:1 relationship with net acid excretion via the gill. This study illustrates the intimate link between intestinal HCO3− production and osmoregulation with acid-base balance and respiratory gas exchange and the specific controlling role of ingested Ca2+ independent of any other ion or overall osmolality in marine teleost fish. PMID:20130227

Experimental study of influence characteristics of flue gas fly ash on acid dew point

NASA Astrophysics Data System (ADS)

Song, Jinhui; Li, Jiahu; Wang, Shuai; Yuan, Hui; Ren, Zhongqiang

2017-12-01

The long-term operation experience of a large number of utility boilers shows that the measured value of acid dew point is generally lower than estimated value. This is because the influence of CaO and MgO on acid dew point in flue gas fly ash is not considered in the estimation formula of acid dew point. On the basis of previous studies, the experimental device for acid dew point measurement was designed and constructed, and the acid dew point under different smoke conditions was measured. The results show that the CaO and MgO in the flue gas fly ash have an obvious influence on the acid dew point, and the content of the fly ash is negatively correlated with the temperature of acid dew point At the same time, the concentration of H2SO4 in flue gas is different, and the acid dew point of flue gas is different, and positively correlated with the acid dew point.

Optical fiber evanescent absorption sensors for high-temperature gas sensing in advanced coal-fired power plants

NASA Astrophysics Data System (ADS)

Buric, Michael P.; Ohodnicky, Paul R.; Duy, Janice

2012-10-01

Modern advanced energy systems such as coal-fired power plants, gasifiers, or similar infrastructure present some of the most challenging harsh environments for sensors. The power industry would benefit from new, ultra-high temperature devices capable of surviving in hot and corrosive environments for embedded sensing at the highest value locations. For these applications, we are currently exploring optical fiber evanescent wave absorption spectroscopy (EWAS) based sensors consisting of high temperature core materials integrated with novel high temperature gas sensitive cladding materials. Mathematical simulations can be used to assist in sensor development efforts, and we describe a simulation code that assumes a single thick cladding layer with gas sensitive optical constants. Recent work has demonstrated that Au nanoparticle-incorporated metal oxides show a potentially useful response for high temperature optical gas sensing applications through the sensitivity of the localized surface plasmon resonance absorption peak to ambient atmospheric conditions. Hence, the simulation code has been applied to understand how such a response can be exploited in an optical fiber based EWAS sensor configuration. We demonstrate that interrogation can be used to optimize the sensing response in such materials.

Use of ferrous chelates of SH-containing amino acids and peptides for the removal of NO/sub x/ and SO/sub 2/ from flue gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, S.G.; Littlejohn, D.; Liu, D.K.

1988-11-01

The use of ferrous complexes of SH-containing amino acids and peptides for the removal of NO and SO/sub 2/ in wet flue gas clean-up systems is reported. The ferrous chelates investigated in the present study include those of cysteine, N-acetylcysteine, penicillamine, N-acetylpenicillamine, glutathine, and cysteinylglycine. Compared to conventional chelates such as EDTA, these thioamino acids/peptides not only can stabilize ferrous ion in alkaline solutions to promote the absorption of NO but are also capable of rapidly reducing any ferric ions formed during the scrubbing process back to ferrous ions so that continual absorption of NO can be achieved. In themore » case of ferrous cysteine and ferrous penicillamine, most of the absorbed NO is reduced to N/sub 2/. The disulfide form of several of the thioamino acids/peptides produced upon oxidation can be conveniently reduced by SO/sub 2/ and H/sub 2/S to regenerate the starting materials, thus making possible the recycling of the reagents.« less

Optical Absorptions of Oxygenated Carbon Chain Cations in the Gas Phase

NASA Astrophysics Data System (ADS)

Hardy, F.-X.; Rice, C. A.; Chakraborty, A.; Fulara, J.; Maier, J. P.

2016-06-01

The gas-phase electronic spectra of linear OC4O+ and a planar C6H2O+ isomer were obtained at a rotational temperature of ≈10 K. Absorption measurements in a 6 K neon matrix were followed by gas-phase observations in a cryogenic radiofrequency ion trap. The origin bands of the 1{}2{{{\\Pi }}}u ≤ftarrow X{}2{{{\\Pi }}}g transition of OC4O+ and the 1{}2A{}2 ≤ftarrow X{}2B1 of HCCC(CO)CCH+ lie at 417.31 ± 0.01 nm and 523.49 ± 0.01 nm, respectively. These constitute the first electronic spectra of oxygenated carbon chain cations studied under conditions that are relevant to the diffuse interstellar bands (DIBs), as both have a visible transition. The recent analysis of the 579.5 nm DIB indicates that small carriers, five to seven heavy atoms, continue to be possible candidates (Huang & Oka 2015). Astronomical implications are discussed regarding this kind of oxygenated molecules.

Real-Time Analysis of Isoprene in Breath by Using Ultraviolet-Absorption Spectroscopy with a Hollow Optical Fiber Gas Cell

PubMed Central

Iwata, Takuro; Katagiri, Takashi; Matsuura, Yuji

2016-01-01

A breath analysis system based on ultraviolet-absorption spectroscopy was developed by using a hollow optical fiber as a gas cell for real-time monitoring of isoprene in breath. The hollow optical fiber functions as an ultra-small-volume gas cell with a long path. The measurement sensitivity of the system was evaluated by using nitric-oxide gas as a gas sample. The evaluation result showed that the developed system, using a laser-driven, high-intensity light source and a 3-m-long, aluminum-coated hollow optical fiber, could successfully measure nitric-oxide gas with a 50 ppb concentration. An absorption spectrum of a breath sample in the wavelength region of around 200–300 nm was measured, and the measured spectrum revealed the main absorbing components in breath as water vapor, isoprene, and ozone converted from oxygen by radiation of ultraviolet light. The concentration of isoprene in breath was estimated by multiple linear regression. The regression analysis results showed that the proposed analysis system enables real-time monitoring of isoprene during the exhaling of breath. Accordingly, it is suitable for measuring the circadian variation of isoprene. PMID:27929387

Real-Time Analysis of Isoprene in Breath by Using Ultraviolet-Absorption Spectroscopy with a Hollow Optical Fiber Gas Cell.

PubMed

Iwata, Takuro; Katagiri, Takashi; Matsuura, Yuji

2016-12-05

A breath analysis system based on ultraviolet-absorption spectroscopy was developed by using a hollow optical fiber as a gas cell for real-time monitoring of isoprene in breath. The hollow optical fiber functions as an ultra-small-volume gas cell with a long path. The measurement sensitivity of the system was evaluated by using nitric-oxide gas as a gas sample. The evaluation result showed that the developed system, using a laser-driven, high-intensity light source and a 3-m-long, aluminum-coated hollow optical fiber, could successfully measure nitric-oxide gas with a 50 ppb concentration. An absorption spectrum of a breath sample in the wavelength region of around 200-300 nm was measured, and the measured spectrum revealed the main absorbing components in breath as water vapor, isoprene, and ozone converted from oxygen by radiation of ultraviolet light. The concentration of isoprene in breath was estimated by multiple linear regression. The regression analysis results showed that the proposed analysis system enables real-time monitoring of isoprene during the exhaling of breath. Accordingly, it is suitable for measuring the circadian variation of isoprene.

Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

NASA Astrophysics Data System (ADS)

Sun, Luming; Zhou, Hongyan; Ji, Tuo; Jiang, Peng; Liu, Bo; Liu, Wenjuan; Pan, Xiang; Shi, Xiheng; Wang, Jianguo; Wang, Tinggui; Yang, Chenwei; Zhang, Shaohua; Miller, Lauren P.

2017-04-01

In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ˜700 and ˜1400 km s-1 relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do not change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V-band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ˜700 km s-1 has a density in the range of 109 to 1010 cm-3 and a distance of ˜1 pc, and the gas with blueshift velocity of ˜1400 km s-1 has a density of 103 cm-3 and a distance of ˜1 kpc.

Light absorption by secondary organic aerosol from α-pinene: Effects of oxidants, seed aerosol acidity, and relative humidity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Chen; Gyawali, Madhu; Zaveri, Rahul A.

2013-10-25

It is well known that light absorption from dust and black carbon aerosols has a warming effect on climate while light scattering from sulfate, nitrate, and sea salt aerosols has a cooling effect. However, there are large uncertainties associated with light absorption and scattering by different types of organic aerosols, especially in the near-UV and UV spectral regions. In this paper, we present the results from a systematic laboratory study focused on measuring light absorption by secondary organic aerosols (SOAs) generated from dark α-pinene + O 3 and α-pinene + NO x + O 3 systems in the presence ofmore » neutral and acidic sulfate seed aerosols. Light absorption was monitored using photoacoustic spectrometers at four different wavelengths: 355, 405, 532, and 870 nm. Significant light absorption at 355 and 405 nm was observed for the SOA formed from α-pinene + O 3 + NO 3 system only in the presence of highly acidic sulfate seed aerosols under dry conditions. In contrast, no absorption was observed when the relative humidity was elevated to greater than 27% or in the presence of neutral sulfate seed aerosols. Organic nitrates in the SOA formed in the presence of neutral sulfate seed aerosols were found to be nonabsorbing, while the light-absorbing compounds are speculated to be aldol condensation oligomers with nitroxy organosulfate groups that are formed in highly acidic sulfate aerosols. Finally and overall, these results suggest that dark α-pinene + O 3 and α-pinene + NO x + O 3 systems do not form light-absorbing SOA under typical atmospheric conditions.« less

Development of a novel microemulsion for oral absorption enhancement of all-trans retinoic acid.

PubMed

Subongkot, Thirapit; Ngawhirunpat, Tanasait

2017-01-01

This study was aimed to develop a novel microemulsion that contained oleth-5 as a surfactant to enhance the oral absorption of all-trans retinoic acid (ATRA). The prepared microemulsion was evaluated for its particle size, shape, zeta potential, in vitro release, in vitro intestinal absorption, intestinal membrane cytotoxicity and stability. The obtained microemulsion was spherical in shape with a particle size of <200 nm and a negative surface charge. The in vitro release of the ATRA-loaded microemulsion was best fit with the zero-order model. This microemulsion significantly improved the intestinal absorption of ATRA. Confocal laser scanning microscopy analysis using a fluorescent dye-loaded microemulsion also confirmed the intestinal absorption result. The intestinal membrane cytotoxicity of the ATRA-loaded microemulsion did not differ from an edible oil (fish oil). Stability testing showed that the ATRA-loaded microemulsion was more stable at 25°C than 40°C.

Emergency membrane contactor based absorption system for ammonia leaks in water treatment plants.

PubMed

Shao, Jiahui; Fang, Xuliang; He, Yiliang; Jin, Qiang

2008-01-01

Abstract Because of the suspected health risks of trihalomethanes (THMs), more and more water treatment plants have replaced traditional chlorine disinfection process with chloramines but often without the proper absorption system installed in the case of ammonia leaks in the storage room. A pilot plant membrane absorption system was developed and installed in a water treatment plant for this purpose. Experimentally determined contact angle, surface tension, and corrosion tests indicated that the sulfuric acid was the proper choice as the absorbent for leaking ammonia using polypropylene hollow fiber membrane contactor. Effects of several operating conditions on the mass transfer coefficient, ammonia absorption, and removal efficiency were examined, including the liquid concentration, liquid velocity, and feed gas concentration. Under the operation conditions investigated, the gas absorption efficiency over 99.9% was achieved. This indicated that the designed pilot plant membrane absorption system was effective to absorb the leaking ammonia in the model storage room. The removal rate of the ammonia in the model storage room was also experimentally and theoretically found to be primarily determined by the ammonia suction flow rate from the ammonia storage room to the membrane contactor. The ammonia removal rate of 99.9% was expected to be achieved within 1.3 h at the ammonia gas flow rate of 500 m3/h. The success of the pilot plant membrane absorption system developed in this study illustrated the potential of this technology for ammonia leaks in water treatment plant, also paved the way towards a larger scale application.

Wavelength modulation diode laser absorption spectroscopy for high-pressure gas sensing

NASA Astrophysics Data System (ADS)

Sun, K.; Chao, X.; Sur, R.; Jeffries, J. B.; Hanson, R. K.

2013-03-01

A general model for 1 f-normalized wavelength modulation absorption spectroscopy with nf detection (i.e., WMS- nf) is presented that considers the performance of injection-current-tuned diode lasers and the reflective interference produced by other optical components on the line-of-sight (LOS) transmission intensity. This model explores the optimization of sensitive detection of optical absorption by species with structured spectra at elevated pressures. Predictions have been validated by comparison with measurements of the 1 f-normalized WMS- nf (for n = 2-6) lineshape of the R(11) transition in the 1st overtone band of CO near 2.3 μm at four different pressures ranging from 5 to 20 atm, all at room temperature. The CO mole fractions measured by 1 f-normalized WMS-2 f, 3 f, and 4 f techniques agree with calibrated mixtures within 2.0 %. At conditions where absorption features are significantly broadened and large modulation depths are required, uncertainties in the WMS background signals due to reflective interference in the optical path can produce significant error in gas mole fraction measurements by 1 f-normalized WMS-2 f. However, such potential errors can be greatly reduced by using the higher harmonics, i.e., 1 f-normalized WMS- nf with n > 2. In addition, less interference from pressure-broadened neighboring transitions has been observed for WMS with higher harmonics than for WMS-2 f.

Effects of simulated flue gas on components of Scenedesmus raciborskii WZKMT.

PubMed

Li, Xie-kun; Xu, Jing-liang; Guo, Ying; Zhou, Wei-zheng; Yuan, Zhen-hong

2015-08-01

Scenedesmus raciborskii WZKMT cultured with simulated flue gas was investigated. Cellular components, including total sugar, starch, chlorophyll, protein and lipid, were compared between simulated flue gas and 7% (v/v) CO2. Dissolution of SO2 and NO in simulated flue gas led to pH decrease and toxicity to microalgae cells. Furthermore, the death or aging of microalgae cells reduced the buffer capacity and caused decrease of simulated flue gas absorption. With 7% CO2, the highest total sugar and starch content could attain to 66.76% and 53.16%, respectively, which indicated S. raciborskii WZKMT is a desired feedstock candidate for bioethanol production. Microalgae growth and starch accumulation was inhibited, while cells produced more chlorophyll, protein and lipid when simulated flue gas was the carbon source. Fatty acids composition analysis indicated that there was no significant distinction on fatty acids relative content (fatty acid/TFA) between cells aerated using simulated flue gas and 7% CO2. Copyright © 2015 Elsevier Ltd. All rights reserved.

A search for ultraviolet circumstellar gas absorption features in alpha Piscis Austrinus (Fomalhaut), a possible Beta Pictoris-like system

NASA Technical Reports Server (NTRS)

Cheng, K.-P.; Bruhweiler, Fred C.; Kondo, Yoji

1994-01-01

Archival high-dispersion International Ultraviolet Explorer (IUE) spectra have been used to search for circumstellar gas absorption features in alpha PsA (A3 V), a nearby (6.7 pc) proto-planetary system candidate. Recent sub-millimeter mapping observations around the region of alpha PsA indicate a spatially resolved dust disk like the one seen around Beta Pic. To determine how closely this putative disk resembles that of Beta Pic, we have searched for signatures of circumstellar gaseous absorption in all the available IUE high-dispersion data of alpha PsA. Examination of co-added IUE spectra shows weak circumstellar absorptions from excited levels in the resonance multiplet of Fe II near 2600 A. We also conclude that the sharp C I feature near 1657 A, previously identified as interstellar absorption toward alpha PsA, likely has a circumstellar origin. However, because the weakness of these absorption features, we will consider the presence of circumstellar gas as tentative and should be verified by using the Goddard High-Resolution Spectrograph aboard the Hubble Space Telescope. No corresponding circumstellar absorption is detected in higher ionization Fe III and Al III. Since the collisionally ionized nonphotospheric Al III resonance absorption seen in Beta Pic is likely formed close to the stellar surface, its absence in the UV spectra of alpha PsA could imply that, in contrast with Beta Pic, there is no active gaseous disk infall onto the central star. In the alpha PsA gaseous disk, if we assume a solar abundance for iron and all the iron is in the form of Fe II, plus a disk temperature of 5000 K, the Fe II UV1 absorption at 2611.8743 A infers a total hydrogen column density along the line of sight through the circumstellar disk of N(H) approximately equals 3.8 x 10(exp 17)/cm.

Intestinal absorption and liver uptake of medium-chain fatty acids in non-anaesthetized pigs.

PubMed

Guillot, E; Vaugelade, P; Lemarchal, P; Rérat, A

1993-03-01

In order to study the rate of intestinal absorption and hepatic uptake of medium-chain fatty acids (MCFA), six growing pigs, mean body weight 65 kg, were fitted with a permanent fistula in the duodenum and with three catheters in the portal vein, carotid artery and hepatic vein respectively. Two electromagnetic flow probes were also set up, one around the portal vein and one around the hepatic artery. A mixture of octanoic and decanoic acids, esterified as medium-chain triacylglycerols, together with maltose dextrine and a nitrogenous fraction was continuously infused for 1 h into the duodenum. Samples of blood were withdrawn from the three vessels at regular intervals for 12 h and further analysed for their non-esterified octanoic and decanoic acid contents. The concentration of non-esterified octanoic and decanoic acids in the portal blood rose sharply after the beginning of each infusion and showed a biphasic time-course with two maximum values, one after 15 min and a later one between 75 and 90 min. Only 65% of octanoic acid infused into the duodenum and 54% of decanoic acid were recovered in the portal flow throughout each experiment. The amounts of non-esterified MCFA taken up per h by the liver were close to those absorbed from the gut via the portal vein within the same periods of time, showing that the liver is the main site of utilization of MCFA in pigs. These results have been discussed with a special emphasis laid on the possible mechanisms of the biphasic time-course of MCFA absorption and the incomplete recovery in the portal blood of the infused fatty acids.

Gas-phase Absorption of {{\\rm{C}}}_{70}^{2+} below 10 K: Astronomical Implications

NASA Astrophysics Data System (ADS)

Campbell, E. K.; Holz, M.; Maier, J. P.

2017-02-01

The electronic spectrum of the fullerene dication {{{C}}}702+ has been measured in the gas phase at low temperature in a cryogenic radiofrequency ion trap. The spectrum consists of a strong origin band at 7030 Å and two weaker features to higher energy. The bands have FWHMs of 35 Å indicating an excited state lifetime on the order of one-tenth of a picosecond. Absorption cross-section measurements yield (2 ± 1) × 10-15 cm2 at 7030 Å. These results are used to predict the depth of diffuse interstellar bands (DIBs) due to the absorption by {{{C}}}702+. At an assumed column density of 2 × 1012 cm-2 the attenuation of starlight at 7030 Å is around 0.4% and thus the detection of such a shallow and broad interstellar band would be difficult. The electronic spectrum of {{{C}}}602+ shows no absorptions in the visible. Below 4000 Å the spectra of C60, {{{C}}}60+ and {{{C}}}602+ are similar. The large intrinsic FWHM of the features in this region, ˜200 Å for the band near 3250 Å, make them unsuitable for DIB detection.

Fourier Transform Infrared Absorption Spectroscopy of Gas-Phase and Surface Reaction Products during Si Etching in Inductively Coupled Cl2 Plasmas

NASA Astrophysics Data System (ADS)

Miyata, Hiroki; Tsuda, Hirotaka; Fukushima, Daisuke; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2011-10-01

A better understanding of plasma-surface interactions is indispensable during etching, including the behavior of reaction or etch products, because the products on surfaces and in the plasma are important in passivation layer formation through their redeposition on surfaces. In practice, the nanometer-scale control of plasma etching would still rely largely on such passivation layer formation as well as ion-enhanced etching on feature surfaces. This paper presents in situ Fourier transform infrared (FTIR) absorption spectroscopy of gas-phase and surface reaction products during inductively coupled plasma (ICP) etching of Si in Cl2. The observation was made in the gas phase by transmission absorption spectroscopy (TAS), and also on the substrate surface by reflection absorption spectroscopy (RAS). The quantum chemical calculation was also made of the vibrational frequency of silicon chloride molecules. The deconvolution of the TAS spectrum revealed absorption features of Si2Cl6 and SiClx (x = 1-3) as well as SiCl4, while that of the RAS spectrum revealed relatively increased absorption features of unsaturated silicon chlorides. A different behavior was also observed in bias power dependence between the TAS and RAS spectra.

Development of a novel microemulsion for oral absorption enhancement of all-trans retinoic acid

PubMed Central

Subongkot, Thirapit; Ngawhirunpat, Tanasait

2017-01-01

This study was aimed to develop a novel microemulsion that contained oleth-5 as a surfactant to enhance the oral absorption of all-trans retinoic acid (ATRA). The prepared microemulsion was evaluated for its particle size, shape, zeta potential, in vitro release, in vitro intestinal absorption, intestinal membrane cytotoxicity and stability. The obtained microemulsion was spherical in shape with a particle size of <200 nm and a negative surface charge. The in vitro release of the ATRA-loaded microemulsion was best fit with the zero-order model. This microemulsion significantly improved the intestinal absorption of ATRA. Confocal laser scanning microscopy analysis using a fluorescent dye-loaded microemulsion also confirmed the intestinal absorption result. The intestinal membrane cytotoxicity of the ATRA-loaded microemulsion did not differ from an edible oil (fish oil). Stability testing showed that the ATRA-loaded microemulsion was more stable at 25°C than 40°C. PMID:28831254

Highly ionized gas absorption in the disk and halo toward HD 167756 at 3.5 kilometers per second resolution

NASA Technical Reports Server (NTRS)

Savage, Blair D.; Sembach, Kenneth R.; Cardelli, Jason A.

1994-01-01

High-resolution spectra of interstellar Si IV, C IV, and N V absorption lines along the 4 kpc path to the inner Galaxy star HD 167756 at z = -0.85 kpc are presented. The spectra were obtained with the echelle mode of Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) and have signal-to-noise ratios ranging from 23 to 38. The high resolution of the measurements full width at half maximum (FWHM = 3.5 km/s) results in fully resolved line profiles for the highly ionized gas absorption. The measurements provide information on the column density per unit velocity, N(v), as a function of velocity for Si IV, C IV, and N V. The C IV and N V profiles extend from -70 to +70 km/s, while the Si IV profiles extend from -40 to +70 km/s. The integrated logarithmic column densities are long N(Si IV) = 13.09 +/- 0.02, log N(C IV) = 13.83 +/- 0.02, and log N(N V) = 13.56 +/- 0.03. The N V profile is broad, asymmetric, and featureless, while the Si IV profile contains narrow absorption components near V(sub LSR) = -19, 0, +20, and +52 km/s with Doppler spread parameters, b about = 10-12 km/s. The C IV profile contains both broad and narrow structure. The high ion feature near +52 km/s is also detected in the low-ionization lines of Ca II, O I, Si II, and Fe II. The other narrow Si IV and C IV components occur within several km/s of components seen in low-ionization species. The sight line contains at least two types of highly ionized gas. One type gives rise to a broad N V profile, and the other results in the more structured Si IV profile. The C IV profile contains contributions from both types of highly ionized gas. The broad but asymmetric N V profile is well represented by a large Galactic scale height gas which is participating in Galactic rotation and has a combination of thermal and turbulent broadening with b(sub tot) about = 42 km/s. The C IV to N V abundance ratio of 1.0 +/- 0.3 for the gas implies T about 1.6 x 10(exp 5) K or about 8 x 10

Outskirts of Distant Galaxies in Absorption

NASA Astrophysics Data System (ADS)

Chen, Hsiao-Wen

QSO absorption spectroscopy provides a sensitive probe of both the neutral medium and diffuse ionized gas in the distant Universe. It extends 21 cm maps of gaseous structures around low-redshift galaxies both to lower gas column densities and to higher redshifts. Combining galaxy surveys with absorption-line observations of gas around galaxies enables comprehensive studies of baryon cycles in galaxy outskirts over cosmic time. This chapter presents a review of the empirical understanding of the cosmic neutral gas reservoir from studies of damped Lyα absorbers (DLAs). It describes the constraints on the star formation relation and chemical enrichment history in the outskirts of distant galaxies from DLA studies. A brief discussion of available constraints on the ionized circumgalactic gas from studies of lower column density Lyα absorbers and associated ionic absorption transitions is presented at the end.

Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Luming; Zhou, Hongyan; Ji, Tuo

In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ∼700 and ∼1400 km s{sup −1} relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do notmore » change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V -band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ∼700 km s{sup −1} has a density in the range of 10{sup 9} to 10{sup 10} cm{sup −3} and a distance of ∼1 pc, and the gas with blueshift velocity of ∼1400 km s{sup −1} has a density of 10{sup 3} cm{sup −3} and a distance of ∼1 kpc.« less

Observing random walks of atoms in buffer gas through resonant light absorption

NASA Astrophysics Data System (ADS)

Aoki, Kenichiro; Mitsui, Takahisa

2016-07-01

Using resonant light absorption, random-walk motions of rubidium atoms in nitrogen buffer gas are observed directly. The transmitted light intensity through atomic vapor is measured, and its spectrum is obtained, down to orders of magnitude below the shot-noise level to detect fluctuations caused by atomic motions. To understand the measured spectra, the spectrum for atoms performing random walks in a Gaussian light beam is computed, and its analytical form is obtained. The spectrum has 1 /f2 (f is frequency) behavior at higher frequencies, crossing over to a different, but well-defined, behavior at lower frequencies. The properties of this theoretical spectrum agree excellently with the measured spectrum. This understanding also enables us to obtain the diffusion constant, the photon cross section of atoms in buffer gas, and the atomic number density from a single spectral measurement. We further discuss other possible applications of our experimental method and analysis.

Modification of fish skin collagen film and absorption property of tannic acid.

PubMed

Liu, Haiying; Zhao, Lu; Guo, Shidong; Xia, Yu; Zhou, Peng

2014-06-01

Fish collagen is a biomacromolecule material and is usually used as a clarifying agent. However, fish collagen is not recyclable, and sedimentation usually occurs in the clarification process using fish collagen so that the filtration process is inevitable. This work aimed to provide a recyclable modified fish skin collagen film (MFCF) for adsorption of tannic acids. The collagen from channel catfish skin was extracted and used for preparation of the fish skin collagen film (FCF) and MFCF. The result indicated that the mechanical properties of MFCF were improved by addition of 2 ml/L glycerol, 6 ml/L polyvinyl alcohol (PVA) and 2 ml/L glutaraldehyde in 15 g/L collagen solution. As the most important property of adsorption material, the hydroscopicity of MFCF was only 54%, significantly lower than that of FCF (295%). Therefore, MFCF would not collapse in water. The infrared and thermal properties of MFCF were also investigated in this work. Results indicated that, in comparison to FCF, the physical and chemical properties of MFCF had been improved significantly. MFCF had higher shrink temperature (79.3 °C) and it did not collapse in distilled water at normal temperature. Furthermore, absorption and desorption properties of tannic acid were studied. MFCF showed good capability of absorption and desorption of tannic acid, which leaded to the suggestion that MFCF could have potential applications in adsorption material.

Ileal absorption of bile acids in patients with chronic cholestasis: SeHCAT test results and effect of ursodeoxycholic acid (UDCA).

PubMed

Chazouillères, O; Marteau, P; Haniche, M; Jian, R; Poupon, R

1996-12-01

The effect of cholestasis on ileal bile acid absorption is controversial in animal models (up- or down-regulation) and unknown in humans. We therefore studied values of the selena homotaurocholic acid (SeHCAT) test before and after long-term administration (>3 months, 13-15 mg/kg/day) of ursodeoxycholic acid (UDCA) in 27 patients with chronic cholestatic liver diseases (24 women, 3 men; mean age, 50 years; 24 primary biliary cirrhosis, 2 secondary biliary cirrhosis, 2 others). The control group consisted of 14 healthy volunteers. Seven-day SeHCAT percentage retention was identical in the 12 untreated cholestatic patients (serum bilirubin, 75+/-42 micromol/L, alkaline phosphatase, 4.2+/-1.0 N; mean+/-SEM) and in the control group (43.6+/-2.9 and 43.8+/-4.2%, respectively). In the 22 patients treated by UDCA for 38+/-8 months, SeHCAT percentage retention was 20.3+/-3.0%. In the seven patients with the SeHCAT test done before and after UDCA treatment (16+/-5 months), SeHCAT percentage retention decreased significantly under UDCA therapy (42.0+/-4.4 vs 19.4+/-4.1%; P < 0.02). We conclude that, in patients with chronic cholestasis (1) SeHCAT percentage retention is not altered-taken together with the known defect of biliary excretion, this lack of increase in SeHCAT percentage retention argues against up-regulation of bile acid ileal transport; and (2) UDCA treatment induces a decrease in the SeHCAT percentage retention-this effect may be related primarily to a decreased bile acid ileal absorption.

Correcting for trace gas absorption when retrieving aerosol optical depth from satellite observations of reflected shortwave radiation

NASA Astrophysics Data System (ADS)

Patadia, Falguni; Levy, Robert C.; Mattoo, Shana

2018-06-01

Retrieving aerosol optical depth (AOD) from top-of-atmosphere (TOA) satellite-measured radiance requires separating the aerosol signal from the total observed signal. Total TOA radiance includes signal from the underlying surface and from atmospheric constituents such as aerosols, clouds and gases. Multispectral retrieval algorithms, such as the dark-target (DT) algorithm that operates upon the Moderate Resolution Imaging Spectroradiometer (MODIS, on board Terra and Aqua satellites) and Visible Infrared Imaging Radiometer Suite (VIIRS, on board Suomi-NPP) sensors, use wavelength bands in window regions. However, while small, the gas absorptions in these bands are non-negligible and require correction. In this paper, we use the High-resolution TRANsmission (HITRAN) database and Line-By-Line Radiative Transfer Model (LBLRTM) to derive consistent gas corrections for both MODIS and VIIRS wavelength bands. Absorptions from H2O, CO2 and O3 are considered, as well as other trace gases. Even though MODIS and VIIRS bands are similar, they are different enough that applying MODIS-specific gas corrections to VIIRS observations results in an underestimate of global mean AOD (by 0.01), but with much larger regional AOD biases of up to 0.07. As recent studies have been attempting to create a long-term data record by joining multiple satellite data sets, including MODIS and VIIRS, the consistency of gas correction has become even more crucial.

Analysis of gas absorption to a thin liquid film in the presence of a zero-order chemical reaction

NASA Technical Reports Server (NTRS)

Rajagopalan, S.; Rahman, M. M.

1995-01-01

The paper presents a detailed theoretical analysis of the process of gas absorption to a thin liquid film adjacent to a horizontal rotating disk. The film is formed by the impingement of a controlled liquid jet at the center of the disk and subsequent radial spreading of liquid along the disk. The chemical reaction between the gas and the liquid film can be expressed as a zero-order homogeneous reaction. The process was modeled by establishing equations for the conservation of mass, momentum, and species concentration and solving them analytically. A scaling analysis was used to determine dominant transport processes. Appropriate boundary conditions were used to solve these equations to develop expressions for the local concentration of gas across the thickness of the film and distributions of film height, bulk concentration, and Sherwood number along the radius of the disk. The partial differential equation for species concentration was solved using the separation of variables technique along with the Duhamel's theorem and the final analytical solution was expressed using confluent hypergeometric functions. Tables for eigenvalues and eigenfunctions are presented for a number of reaction rate constants. A parametric study was performed using Reynolds number, Ekman number, and dimensionless reaction rate as parameters. At all radial locations, Sherwood number increased with Reynolds number (flow rate) as well as Ekman number (rate of rotation). The enhancement of mass transfer due to chemical reaction was found to be small when compared to the case of no reaction (pure absorption), but the enhancement factor was very significant when compared to pure absorption in a stagnant liquid film. The zero-order reaction processes considered in the present investigation included the absorption of oxygen in aqueous alkaline solutions of sodiumdithionite and rhodium complex catalyzed carbonylation of methanol. Present analytical results were compared to previous theoretical

Application of backscatter absorption gas imaging to the detection of chemicals related to drug production

NASA Astrophysics Data System (ADS)

Kulp, Thomas J.; Garvis, Darrel G.; Kennedy, Randall B.; McRae, Thomas G.

1991-08-01

The application of backscatter absorption gas imaging (BAGI) to the detection of gaseous chemical species associated with the production of illegal drugs is considered. BAGI is a gas visualization technique that allows the imaging of over 70 organic vapors at minimum concentrations of a few to several hundred ppm-m. Present BAGI capabilities at Lawrence Livermore National Laboratory and Laser Imaging Systems are discussed. Eighteen different species of interest in drug-law enforcement are identified as being detectable by BAGI. The chemical remote sensing needs of law enforcement officials are described, and the use of BAGI in meeting some of these needs is outlined.

Current Status Of The NAVSEA Backscatter Absorption Gas Imaging (BAGI) Development Project

NASA Astrophysics Data System (ADS)

Kulp, Thomas J.; Kennedy, Randall B.; Garvis, Darrel G.; McRae, Thomas G.; Stahovec, Joe

1989-07-01

During the last five years, work has been underway at the Lawrence Livermore National Laboratory (LLNL) to develop a method for imaging gas clouds that are normally invisible to the human eye. The effort was initiated to provide an effective means of locating leaks of hazardous vapors. Although conventional point or line-of-sight detectors are well suited to the measurement of gas concentrations, their utility in identifying the origin and direction of travel of gas plumes is limited. To obtain spatial information from sensors that provide only zero- or one-dimensional readings, either sequential readings at many different locations from a single device, or multiplexed simultaneous measurements from a sensor array must be taken. The former approach is time consuming and, therefore, impractical in emergency situations where rapid action is required. The latter is useful only in cases where the probability of a hazardous release is high enough to warrant the prior installation of a sensor network. Either method demands high measuremental precision and sufficient discrimination against both interfering gases and interfering sources of the target gas. Backscatter Absorption Gas Imaging (BAGI) is a new technique that makes gas clouds and their surroundings "visible" in a real-time video image. It is superior to conventional sensors in characterizing the spatial properties of gas clouds because it provides data that are inherently two-dimensional. Less measuremental precision is required by the BAGI technique because it conveys information as contrasts between different areas in an image rather than as absolute concentration values. Furthermore, the pictorial display of this information allows it to be rapidly assimilated by emergency-response teams. The size and orientation of the plume are evident through comparison with familiar objects that also appear in the image. Subtler evaluations can be made as well, such as the distinction between innocous and hazardous

Absorption of CO2 from modified flue gases of power generation Tarahan chemically using NaOH and Na2CO3 and biologically using microalgae

NASA Astrophysics Data System (ADS)

Purba, Elida; Agustina, Dewi; Putri Pertama, Finka; Senja, Fita

2018-03-01

This research was carried out on the absorption of CO2 from the modified flue gases of power generation Tarahan using NaOH (sodium hydroxide) and Na2CO3 (sodium carbonate). The operation was conducted in a packed column absorber and then the output gases from the packed column was fed into photo-bioreactor for biological absorption. In the photo-bioreactor, two species of microalgae, N. occulata and T. chuii, were cultivated to both absorb CO2 gas and to produce biomass for algal oil. The aims of this research were, first, to determine the effect of absorbent flow rate on the reduction of CO2 and on the decrease of output gas temperature, second, to determine the characteristics of methyl ester obtained from biological absorption process. Flow rates of the absorbent were varied as 1, 2, and 3 l/min. The concentrations of NaOH and Na2CO3 were 1 M at a constant gas flow rate of 6 l/min. The output concentrations of CO2 from the absorber was analyzed using Gas Chromatography 2014-AT SHIMADZU Corp 08128. The results show that both of the absorbents give different trends. From the absorption using NaOH, it can be concluded that the higher the flow rate, the higher the absorption rate obtained. The highest flow rate achieved maximum absorption of 100%. On the other hand, absorption with Na2CO3 revealed the opposite trend where the higher the flow rates the lower the absorption rate. The highest absorption using Na2CO3 was obtained with the lowest flow rate, 1 l/min, that was 45,5%. As the effect of flow rate on output gas temperature, the temperature decreased with increasing flow rates for both absorbents. The output gas temperature for NaOH and Na2CO3 were consecutively 35 °C and 31 °C with inlet gas temperature of 50°C. Absorption of CO2 biologically resulted a reduction of CO2 up to 60% from the input gas concentration. Algal oil was extracted with mixed hexane and chloroform to obtain algal oil. Extracted oil was transesterified to methyl ester using sodium

First steps towards a gas-phase acidity ladder for derivatized fullerene dications

NASA Astrophysics Data System (ADS)

Petrie, Simon; Javahery, Gholamreza; Bohme, Diethard K.

1993-03-01

C2+60 can be derivatized by gas-phase ion/molecule reactions with polar hydrogen-bearing molecules. The adduct dications so produced may then undergo proton transfer to neutrals. The occurrence or absence of proton transfer as a secondary process gives information on the gas-phase acidity of the dicationic species C60·(XH)2+in. We have performed studies using a selected-ion flow tube at 294 ± 2 K and 0.35 ± 0.01 Torr, and have used observed reactivity of such dicationic fullerene adducts to determine upper or lower limits to their apparent and absolute gas-phase acidities. We present also a rationale for assessing the proton-transfer reactivity of dications via the apparent gas-phase acidity of these species, rather than the traditional use of gas-phase basicities or proton affinities. We propose that further studies of proton transfer from polycharged fullerene adducts may provide considerable useful information to model the reactivity of polyprotonated proteins and other large molecular polycatiions which can now be produced by techniques such as electrospray ionization.

Photometric and fluorometric continuous kinetic assay of acid phosphatases with new substrates possessing longwave absorption and emission maxima.

PubMed

Koller, E; Wolfbeis, O S

1984-11-15

A direct and continuous kinetic method for the photometric and fluorometric determination of various acid phosphatases is described. It is based on new coumarin-derived phosphates, which after enzymatic hydrolysis undergo dissociation to form intensely colored and strongly fluorescent phenolate anions. The latter have absorption maxima ranging from 385 to 505 nm, and fluorescence maxima between 470 and 595 nm. The new substrates were compared with respect to their rate of enzymatic hydrolysis, optimum pH, and detection limits of acid phosphatase from potato and wheat germ. Detection limits of 0.001 unit/ml were found by photometry, and as low as 0.00006 unit/ml by fluorometry. The principal advantages of the new substrates over existing ones are longwave absorptions and emissions, large Stokes shifts, and the low pKa values of the corresponding phenols, thus allowing a direct and continuous assay of acid phosphatase even in weakly acidic solutions.

Acid effects on the measurement of mercury by cold vapor atomic absorption spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adeloju, S.B.; Mann, T.F.

1987-07-01

The influence of nitric, hydrochloric and sulfuric acids on the measurement of mercury by cold vapor atomic absorption spectrometry has been investigated. Small pre-reduction peaks associated with the instability of mercury were observed in solutions containing less than or equal to 12.5, < 2 and less than or equal to 12.5% v/v of each acid, respectively. Mercury was found to be most stable in greater than or equal to 2% v/v hydrochloric acid and the measured absorbance was not greatly influenced by varying concentration of the acid. The mercury absorbance measurements were more sensitive in solutions containing less than ormore » equal to 6.3% v/v hydrochloric acid than in similar concentrations of nitric and sulfuric acids. The use of the three acids as a digestion mixture result in serious interference from nitrogen oxides. The interference was removed by use of expelling agents such as urea and sulfamic acid or overcome by use of excess stannous chloride, prior to the reduction of mercury(II) ions. The determination of mercury in NBS albacore tuna using both of these approaches to overcome the interference problem proved to be successful.« less

Mechanistic understanding of the effect of PPIs and acidic carbonated beverages on the oral absorption of itraconazole based on absorption modeling with appropriate in vitro data.

PubMed

Fotaki, Nikoletta; Klein, Sandra

2013-11-04

Proton pump inhibitors (PPIs) are potent gastric acid suppressing agents and are among the most widely sold drugs in the world. However, even though these antisecretory agents are regarded as safe, they can alter the pharmacokinetics of coadministered drugs. Due to the suppression of gastric acid secretion, they can significantly alter the intragastric pH conditions and are thus likely to affect the bioavailability of coadministered drugs requiring an acidic gastric environment for dissolution and subsequent absorption. Among these drugs can be found itraconazole, a poorly soluble triazole-type antifungal compound. Based on observations reported in the literature, gastric pH alterations due to the coadministration of PPIs or acidic beverages can significantly decrease (PPI) or increase (e.g., Coca-Cola) the bioavailability of this compound. In the present work we estimated the fraction of itraconazole that can be absorbed (fabs) from Sporanox capsules or an itraconazole-HBenBCD complex formulation after oral administration with and without coadministration of a PPI or an acidic (carbonated) beverage. For this purpose, the sensitivity of the two formulations toward the impact of various gastric variations (pH, volume, and emptying rate) as they can result from such administration conditions was studied using solubility and dissolution experiments and a physiologically based absorption model. Simulating coadministration of the two formulations with a PPI resulted in a significant (∼ 10-fold) decrease in itraconazole fabs, indicating the pH to be essential for in vivo dissolution and subsequent absorption. The fabs of itraconazole after coadministration of an acidic beverage (Coca-Cola) was far lower than the fabs obtained for itraconazole alone and did not support the observations reported in the literature. These results clearly indicate that in contrast to PPIs, which seem to affect itraconazole bioavailability mainly via intragastric pH changes, coadministered

Identification of Fatty Acids and Aliphatic Hydrocarbons in Sarcina lutea by Gas Chromatography and Combined Gas Chromatography-Mass Spectrometry

PubMed Central

Tornabene, T. G.; Gelpi, E.; Oró, J.

1967-01-01

The composition and nature of the fatty acids and hydrocarbons of Sarcina lutea were elucidated by gas chromatography and by combined gas chromatography-mass spectrometry. The distribution of fatty acids found in S. lutea showed two families of pairs, or dyads, of saturated monocarboxylic acids (C12–C18) with and without methyl branching. These pairs of fatty acids showed a pattern of iso and anteiso structures for C13, C15, and C17, and iso and normal structures for C12, C14, and C16. Only the C18 showed unsaturation. The distribution of hydrocarbons in the range C22–C29 showed two families of tetrads of unsaturated aliphatic hydrocarbons all showing methyl branching. Each tetrad was composed of four isomers identified as two iso olefins and two anteiso olefins. The only difference between the tetrads pertaining to different families was found in the relative gas chromatographic retention times of the last two components of each group. PMID:6039356

Perfluorocarbon-associated gas exchange in normal and acid-injured large sheep.

PubMed

Hernan, L J; Fuhrman, B P; Kaiser, R E; Penfil, S; Foley, C; Papo, M C; Leach, C L

1996-03-01

We hypothesized that a) perfluorocarbon-associated gas exchange could be accomplished in normal large sheep; b) the determinants of gas exchange would be similar during perfluorocarbon-associated gas exchange and conventional gas ventilation; c)in large animals with lung injury, perfluorocarbon-associated gas exchange could be used to enhance gas exchange without adverse effects on hemodynamics; and d) the large animal with lung injury could be supported with an FIO2 of <1.0 during perfluorocarbon-associated gas exchange. Prospective, observational animal study and prospective randomized, controlled animal study. An animal laboratory in a university setting. Thirty adult ewes. Five normal ewes (61.0 +/- 4.0 kg) underwent perfluorocarbon-associated gas exchange to ascertain the effects of tidal volume, end-inspiratory pressure, and positive end-expiratory pressure (PEEP) on oxygenation. Respiratory rate, tidal volume, and minute ventilation were studied to determine their effects on CO2 clearance. Sheep, weighing 58.9 +/- 8.3 kg, had lung injury induced by instilling 2 mL/kg of 0.05 Normal hydrochloric acid into the trachea. Five minutes after injury, PEEP was increased to 10 cm H2O. Ten minutes after injury, sheep with Pao2 values of <100 torr (<13.3 kPa) were randomized to continue gas ventilation (control, n=9) or to institute perfluorocarbon-associated gas exchange (n=9) by instilling 1.6 L of unoxygenated perflubron into the trachea and resuming gas ventilation. Blood gas and hemodynamic measurements were obtained throughout the 4-hr study. Both tidal volume and end-inspiratory pressure influenced oxygenation in normal sheep during perfluorocarbon-associated gas exchange. Minute ventilation determined CO2 clearance during perfluorocarbon-associated gas exchange in normal sheep. After acid aspiration lung injury, perfluorocarbon-associated gas exchange increased PaO2 and reduced intrapulmonary shunt fraction. Hypoxia and intrapulmonary shunting were unabated

Intestinal absorption of medium chain fatty acids: in vivo studies in pigs devoid of exocrine pancreatic secretion.

PubMed

Guillot, E; Lemarchal, P; Dhorne, T; Rerat, A

1994-10-01

In order to study the influence of pancreatic enzyme secretion on the intestinal absorption of medium-chain fatty acids (MCFA), three growing pigs (mean body-weight 61 kg) with ligated and severed pancreatic ducts were fitted with a permanent fistula in the duodenum and with two catheters in the portal vein and carotid artery respectively. An electromagnetic flow probe was also set up around the portal vein. A mixture of octanoic and decanoic acids, esterified as medium-chain triacylglycerols, together with maltose dextrine and nitrogenous fraction was continuously infused for 1 h into the duodenum. Samples of blood were withdrawn from the two vessels at regular intervals of time for 8 h and further analysed for their non-esterified octanoic and decanoic acid contents. The concentrations of non-esterified octanoic and decanoic acid in the portal blood increased slowly after the beginning of each infusion, reaching about 10 times higher values than the basal level. Only 26% of octanoic acid infused in the duodenum and 27% of decanoic acid were recovered in the portal flow throughout each experiment. The possible mechanisms underlying the appearance of MCFA in the portal blood in the absence of pancreatic enzyme secretions and the importance of duodenal absorption of MCT in such physiological conditions have been discussed.

Determination of dichloroacetic acid and trichloroacetic acid in drinking water by acidic methanol esterification and headspace gas chromatography.

PubMed

Wang, Y H; Wong, P K

2005-05-01

A simple and rapid headspace method for gas chromatographic determination of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in drinking water was developed. Acidic methanol esterification followed by a headspace technique using a capillary column gas chromatograph (GC) equipped with an electron capture detector (ECD) was applied to determine the levels of DCAA and TCAA in drinking water. The major advantages of this method are the use of acidic methanol as the derivatization agent instead of the hazardous diazomethane, and esterification is carried out in water instead of organic solvent. DCAA and TCAA methyl esters produced in the reaction were determined directly by a headspace GC/ECD method. The linear correlation coefficients at concentrations ranging from 0 to 60 microg/L were 0.992 and 0.996 for DCAA and TCAA, respectively. The relative standard deviations (RSD, %) for the determination of DCAA and TCAA in drinking water were 15 and 21.3%, respectively (n=3). The detection limits of this method were 3 and 0.5 microg/L for DCAA and TCAA, respectively, and the recovery was 68-103.2% for DCAA and TCAA.

Changes in the absorption of bile acids after total colectomy in patients with an ileostomy or pouch-anal anastomosis.

PubMed

Nasmyth, D G; Johnston, D; Williams, N S; King, R F; Burkinshaw, L; Brooks, K

1989-03-01

Bile acid absorption was investigated using 75Se Taurohomocholate (SeHCAT) in controls and patients who had undergone total colectomy with either conventional ileostomy or pouch-anal anastomosis for ulcerative colitis or adenomatous polyposis. Whole-body retention of SeHCAT after 168 hours was greater in the controls than the patients who had undergone colectomy (P less than .05). Retention of SeHCAT did not differ significantly between patients with an ileostomy and patients with pouch-anal anastomosis, but patients with an ileostomy and ileal resection of more than 20 cm retained less SeHCAT than patients with a pouch-anal anastomosis (P less than .01). Analysis of fecal bile acids from ileostomies and pouches showed that bacterial metabolism of primary conjugated bile acids was greater in patients with a pouch. It was concluded that bile acid absorption was not significantly impaired by construction of a pouch compared with conventional ileostomy, but bacterial metabolism of bile acids was greater in the pouches.

Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

PubMed

Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

2016-02-01

The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress

PubMed Central

Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

2016-01-01

The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

Wavelength modulation spectroscopy--digital detection of gas absorption harmonics based on Fourier analysis.

PubMed

Mei, Liang; Svanberg, Sune

2015-03-20

This work presents a detailed study of the theoretical aspects of the Fourier analysis method, which has been utilized for gas absorption harmonic detection in wavelength modulation spectroscopy (WMS). The lock-in detection of the harmonic signal is accomplished by studying the phase term of the inverse Fourier transform of the Fourier spectrum that corresponds to the harmonic signal. The mathematics and the corresponding simulation results are given for each procedure when applying the Fourier analysis method. The present work provides a detailed view of the WMS technique when applying the Fourier analysis method.

New configurations of a heat recovery absorption heat pump integrated with a natural gas boiler for boiler efficiency improvement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Ming; Abdelaziz, Omar; Yin, Hongxi

2014-11-01

Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150 200 C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50 60more » C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural gas boilers for applications with process fluid return temperatures higher than or close to the dew point of the water vapor in the flue gas.« less

Diode-Laser Absorption Sensor for Line-of-Sight Gas Temperature Distributions

NASA Astrophysics Data System (ADS)

Sanders, Scott T.; Wang, Jian; Jeffries, Jay B.; Hanson, Ronald K.

2001-08-01

Line-of-sight diode-laser absorption techniques have been extended to enable temperature measurements in nonuniform-property flows. The sensing strategy for such flows exploits the broad wavelength-scanning abilities ( >1.7 nm ~ 30 cm-1 ) of a vertical cavity surface-emitting laser (VCSEL) to interrogate multiple absorption transitions along a single line of sight. To demonstrate the strategy, a VCSEL-based sensor for oxygen gas temperature distributions was developed. A VCSEL beam was directed through paths containing atmospheric-pressure air with known (and relatively simple) temperature distributions in the 200 -700 K range. The VCSEL was scanned over ten transitions in the R branch of the oxygen A band near 760 nm and optionally over six transitions in the P branch. Temperature distribution information can be inferred from these scans because the line strength of each probed transition has a unique temperature dependence; the measurement accuracy and resolution depend on the details of this temperature dependence and on the total number of lines scanned. The performance of the sensing strategy can be optimized and predicted theoretically. Because the sensor exhibits a fast time response ( ~30 ms) and can be adapted to probe a variety of species over a range of temperatures and pressures, it shows promise for industrial application.

The physical basis for absorption of light. [effects on wave functions of gas molecules and atoms

NASA Technical Reports Server (NTRS)

Pickett, H. M.

1979-01-01

The effects of light absorption on the wave functions of gas-phase molecules and atoms are investigated by high resolution spectral measurements of radiation emerging from a sample. A Stark-modulated sample of methyl fluoride was irradiated at the 102 GHz rotational transition and the emergent radiation was resolved by means of a spectrum analyzer. For signal oscillator frequencies below or above the molecular resonance by one modulation frequency, the amplitudes of the upper and lower modulation sidebands are found to be of nonuniform intensity, which is inconsistent with amplitude modulation. Emission due to polarization is, however, calculated to be consistent with the results observed, indicating that light absorption should be considered as a subtractive stimulated emission.

Determination of sulfur in kerosene by combustion and molecular absorption spectrometry in the gas phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruschak, M.L.; Syty, A.

1982-08-01

A technique of nonflame molecular adsorption in the gas phase developed for the determination of sulfite trapped in tetrachloromercurate, is described herein for application to the determination of total sulfur in kerosene. The burner head is removed from the atomic absorption spectrometer and replaced with a flow-through absorption cell. A special reaction vessel is used to evolve SO/sub 2/ from the sulfite in a precise and convenient manner. The transient absorbance caused by the SO/sub 2/, as it is carried through the absorption cell, is measured. Both spiked and unspiked samples of kerosene were analyzed, and the reproducibility of themore » repeated runs is evidenced by a relative standard deviation from the mean of 5% for the unspiked kerosene and 4% for the spiked kerosene. If the detection level is defined as that concentration of S which gives a % S twice the standard deviation from the mean yields, the detection limit for the present method is 0.002% S by weight in kerosene.« less

Natural gas pipeline leak detector based on NIR diode laser absorption spectroscopy.

PubMed

Gao, Xiaoming; Fan, Hong; Huang, Teng; Wang, Xia; Bao, Jian; Li, Xiaoyun; Huang, Wei; Zhang, Weijun

2006-09-01

The paper reports on the development of an integrated natural gas pipeline leak detector based on diode laser absorption spectroscopy. The detector transmits a 1.653 microm DFB diode laser with 10 mW and detects a fraction of the backscatter reflected from the topographic targets. To eliminate the effect of topographic scatter targets, a ratio detection technique was used. Wavelength modulation and harmonic detection were used to improve the detection sensitivity. The experimental detection limit is 50 ppmm, remote detection for a distance up to 20 m away topographic scatter target is demonstrated. Using a known simulative leak pipe, minimum detectable pipe leak flux is less than 10 ml/min.

Differential-optoacoustic absorption detector

NASA Technical Reports Server (NTRS)

Shumate, M. S.

1977-01-01

Two-cell spectrophone detects trace amounts of atmospheric pollutants by measuring absorption coefficients of gases with various laser sources. Device measures pressure difference between two tapered cells with differential manometer. Background signal is reduced by balanced window heating and balanced carrier gas absorption in two cells.

Detectability of cold streams into high-redshift galaxies by absorption lines

NASA Astrophysics Data System (ADS)

Goerdt, Tobias; Dekel, Avishai; Sternberg, Amiel; Gnat, Orly; Ceverino, Daniel

2012-08-01

Cold gas streaming along the dark matter filaments of the cosmic web is predicted to be the major source of fuel for disc buildup, violent disc instability and star formation in massive galaxies at high redshift. We investigate to what extent such cold gas is detectable in the extended circumgalactic environment of galaxies via Lyα absorption and selected low-ionization metal absorption lines. We model the expected absorption signatures using high-resolution zoom-in adaptive mesh refinement cosmological simulations. In the post-processing, we distinguish between self-shielded gas and unshielded gas. In the self-shielded gas, which is optically thick to Lyman continuum radiation, we assume pure collisional ionization for species with an ionization potential greater than 13.6 eV. In the optically-thin, unshielded gas, these species are also photoionized by the metagalactic radiation. In addition to absorption of radiation from background quasars, we compute the absorption line profiles of radiation emitted by the galaxy at the centre of the same halo. We predict the strength of the absorption signal for individual galaxies without stacking. We find that the Lyα absorption profiles produced by the streams are consistent with observations of absorption and emission Lyα profiles in high-redshift galaxies. Due to the low metallicities in the streams, and their low covering factors, the metal absorption features are weak and difficult to detect.

Gas-phase hydration of glyoxylic acid: Kinetics and atmospheric implications.

PubMed

Liu, Ling; Zhang, Xiuhui; Li, Zesheng; Zhang, Yunhong; Ge, Maofa

2017-11-01

Oxocarboxylic acids are one of the most important organic species found in secondary organic aerosols and can be detected in diverse environments. But the hydration of oxocarboxylic acids in the atmosphere has still not been fully understood. Neglecting the hydration of oxocarboxylic acids in atmospheric models may be one of the most important reasons for the significant discrepancies between field measurements and abundance predictions of atmospheric models for oxocarboxylic acids. In the present paper, glyoxylic acid, as the most abundant oxocarboxylic acids in the atmosphere, has been selected as an example to study whether the hydration process can occur in the atmosphere and what the kinetic process of hydration is. The gas-phase hydration of glyoxylic acid to form the corresponding geminal diol and those catalyzed by atmospheric common substances (water, sulfuric acid and ammonia) have been investigated at the CCSD(T)-F12/cc-pVDZ-F12//M06-2X/6-311++G(3df,3pd) level of theory. The contour map of electron density difference of transition states have been further analyzed. It is indicated that these atmospheric common substances can all catalyze on the hydration to some extent and sulfuric acid is the most effective reducing the Gibbs free energy of activation to 9.48 kcal/mol. The effective rate constants combining the overall rate constants and concentrations of the corresponding catalysts have shown that water and sulfuric acid are both important catalysts and the catalysis of sulfuric acid is the most effective for the gas-phase hydration of glyoxylic acid. This catalyzed processes are potentially effective in coastal regions and polluted regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gas-phase Absorptions of {{\\rm{C}}}_{42}{{\\rm{H}}}_{18}^{+} near 8300 Å below 10 K: Astronomical Implications

NASA Astrophysics Data System (ADS)

Campbell, E. K.; Maier, J. P.

2017-11-01

The gas-phase electronic spectrum of {{{C}}}42{{{H}}}18+ ({{HBC}}+) with an origin band at 8281 \\mathringA has been measured below 10 {{K}} by photofragmentation of helium complexes ({{{C}}}42{{{H}}}18+{--}{{He}}n) in a radiofrequency trap. {{HBC}}+ is a medium-sized polycyclic aromatic hydrocarbon (PAH) cation, and using an ion trapping technique it has been possible to record a high-quality gas-phase spectrum to directly compare with astronomical observations. No diffuse interstellar bands (DIBs) have been reported at the wavelengths of the strongest absorption bands in the {{{C}}}42{{{H}}}18+ spectrum. Measurement of absolute absorption cross sections in the ion trap allows upper limits to the column density of this ion to be {10}12 {{cm}}-2, indicating that even PAH cations of this size, which are believed to be stable in the interstellar medium, should be excluded as candidates for at least the strong DIBs.

Measurement of diffusion coefficients important in modeling the absorption rate of carbon dioxide into aqueous N-methyldiethanolamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowley, R.L.; Adams, M.E.; Marshall, T.L.

1997-03-01

Natural gas processors use amine treating processes to remove the acid gases H{sub 2}S and CO{sub 2} from gas streams. Absorption rates of gaseous CO{sub 2} into aqueous N-methyldiethanolamine (MDEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO{sub 2} in solution but very sensitive to the diffusion rate of bicarbonate and protonated MDEA ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. A numerical model was developed on the basis of these observations. The modelmore » was used to regress diffusion coefficients of bicarbonate and protonated amine, which must be equivalent by electroneutrality arguments, from measured absorption rates. Complete modeling of the absorption process also required data for the diffusion coefficient of MDEA in water. These were measured using a Taylor dispersion apparatus. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate and protonated MDEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % MDEA in water.« less

Simultaneous determination of docosahexaenoic acid and eicosapentaenoic acid in common seafood using ultrasonic cell crusher extraction combined with gas chromatography.

PubMed

Zhao, Juanjuan; Ren, Yan; Yu, Chen; Chen, Xiangming; Shi, Yanan

2017-02-01

An effective method for the simultaneous determination of docosahexaenoic acid and eicosapentaenoic acid in common seafood by gas chromatography was developed and validated. Total docosahexaenoic acid and eicosapentaenoic acid were extracted from seafood by ultrasonic cell crusher assisted extraction and methyl esterified for gas chromatography analysis in the presence of the internal standard. The linearity was good (r > 0.999) in 9.59 ∼ 479.5 μg/mL for docosahexaenoic acid and 9.56 ∼ 477.8 μg/mL for eicosapentaenoic acid. The intrarun and interrun precisions were both within 4.8 and 6.1% for the two analytes, while the accuracy was less than 5.8%. The developed method was applied for determination of docosahexaenoic acid and eicosapentaenoic acid in six kinds of seafood. The result showed the content of docosahexaenoic acid and eicosapentaenoic acid was all higher than 1 mg/g in yellow croaker, hairtail, venerupis philippinarum, mussel, and oyster. Our work may be helpful for dietary optimization and production of docosahexaenoic acid and eicosapentaenoic acid. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Variable absorption of clavulanic acid after an oral dose of 25 mg/kg of Clavubactin and Synulox in healthy cats.

PubMed

Vree, Tom B; Dammers, Erik; van Duuren, Eri

2002-05-21

The aims of this investigation were to calculate the pharmacokinetic parameters and to identify parameters, based on individual plasma concentration-time curves of amoxicillin and clavulanic acid in cats, that may govern the observed differences in absorption of both drugs. The evaluation was based on the data from plasma concentration-time curves obtained following a single-dose, open, randomised, two-way crossover phase-I study, each involving 24 female cats treated with two Amoxi-Clav formulations (formulation A was Clavubactin and formulation was B Synulox; 80/20 mg, 24 animals, 48 drug administrations). Plasma amoxicillin and clavulanic acid concentrations were determined using validated bioassay methods. The half-life of elimination of amoxicillin is 1.2 h (t1/2 = 1.24 +/- 0.28 h, Cmax = 12.8 +/- 2.12 microg/ml), and that of clavulanic acid 0.6 h (t1/2 = 0.63 +/- 0.16 h, Cmax = 4.60 +/- 1.68 microg/ml). There is a ninefold variation in the AUCt of clavulanic acid for both formulations, while the AUCt of amoxicillin varies by a factor of two. The highest clavulanic acid AUCt values indicate the best absorption; all other data indicate less absorption. Taking into account that the amoxicillin-to-clavulanic acid dose ratio in the two products tested was 4:1, the blood concentration ratios may actually vary much more, apparently without compromising the products" high efficacy against susceptible microorganisms.

Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yi, Hongming; Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 1125, 350 Shushanhu Road, Hefei, Anhui 230031; Maamary, Rabih

2015-03-09

Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm{sup −1} was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ∼40 mm{sup 3}) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by direct absorption spectroscopy involving a ∼109.5 mmore » multipass cell and a distributed feedback QCL. A minimum detection limit (MDL) of 66 ppbv (1 σ) HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6 × 10{sup −8 }cm{sup −1} W/Hz{sup 1/2}. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding 1σ minimum detected absorption coefficient is ∼1.1 × 10{sup −7 }cm{sup −1} (MDL ∼ 3 ppbv) in 1 s and ∼1.1 × 10{sup −8 }cm{sup −1} (MDL ∼ 330 pptv) in 150 s, respectively, with 1 W laser power.« less

Natural gas leak mapper

DOEpatents

Reichardt, Thomas A [Livermore, CA; Luong, Amy Khai [Dublin, CA; Kulp, Thomas J [Livermore, CA; Devdas, Sanjay [Albany, CA

2008-05-20

A system is described that is suitable for use in determining the location of leaks of gases having a background concentration. The system is a point-wise backscatter absorption gas measurement system that measures absorption and distance to each point of an image. The absorption measurement provides an indication of the total amount of a gas of interest, and the distance provides an estimate of the background concentration of gas. The distance is measured from the time-of-flight of laser pulse that is generated along with the absorption measurement light. The measurements are formated into an image of the presence of gas in excess of the background. Alternatively, an image of the scene is superimosed on the image of the gas to aid in locating leaks. By further modeling excess gas as a plume having a known concentration profile, the present system provides an estimate of the maximum concentration of the gas of interest.

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2011 CFR

2011-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment... procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas Engineers Handbook, Fuel.... In principle, this method consists of titrating hydrogen sulfide in a gas sample directly with a...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2010 CFR

2010-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment... procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas Engineers Handbook, Fuel.... In principle, this method consists of titrating hydrogen sulfide in a gas sample directly with a...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2012 CFR

2012-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment... procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas Engineers Handbook, Fuel.... In principle, this method consists of titrating hydrogen sulfide in a gas sample directly with a...

Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2

PubMed Central

Cummings, Beth; Hamilton, Michelle L.; Ciaffoni, Luca; Pragnell, Timothy R.; Peverall, Rob; Ritchie, Grant A. D.; Hancock, Gus

2011-01-01

The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations. PMID:21512147

Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2.

PubMed

Cummings, Beth; Hamilton, Michelle L; Ciaffoni, Luca; Pragnell, Timothy R; Peverall, Rob; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

2011-07-01

The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations.

Laser absorption phenomena in flowing gas devices

NASA Technical Reports Server (NTRS)

Chapman, P. K.; Otis, J. H.

1976-01-01

A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2013 CFR

2013-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment..., 2011 § 60.648 Optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas... dilute solutions are used. In principle, this method consists of titrating hydrogen sulfide in a gas...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2014 CFR

2014-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment..., 2011 § 60.648 Optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas... dilute solutions are used. In principle, this method consists of titrating hydrogen sulfide in a gas...

Metabolism of Penicillins to Penicilloic Acids and 6-Aminopenicillanic Acid in Man and Its Significance in Assessing Penicillin Absorption

PubMed Central

Cole, M.; Kenig, M. D.; Hewitt, Valerie A.

1973-01-01

Penicillins can be metabolized to penicilloic acids in man, the extent being dependent on the penicillin structure. In the phenoxy penicillin series, phenoxymethyl penicillin was found to be particularly unstable, but the higher homologues were more stable. In the isoxazolyl series, oxacillin was unstable, and progressive insertion of halogen in the phenyl ring increased stability. Ampicillin and amoxycillin showed some instability, ampicillin possibly being the more stable. After intramuscular administration, carbenicillin was very stable in the body, ampicillin was fairly stable, and benzyl penicillin was unstable. It is important to take into account the penicilloic acid content of urine when estimating total absorption of a penicillin. Increased stability in the body as well as slower renal clearance can lead to high concentrations in the serum. Penicilloic acids seemed to be more slowly cleared from the body than penicillins. The liver is probably the site of inactivation. PMID:4364176

Effect of different levels of an ascorbic acid and tea mixture on nonheme iron absorption from a typical Tunisian meal fed to healthy rats.

PubMed

Hamdauoui, M; Doghri, T; Tritar, B

1995-01-01

The aim of our study was to evaluate the bioavailability of iron from a typical Tunisian meal 'couscous' provided to healthy rats with or without appropriate mixtures of tea plus ascorbic acid and to search for the optimal amount of ascorbic acid able to overcome the inhibitory effect of tea prepared under realistic Tunisian circumstances. Our findings show that a tea decoction (100 mg/ml) reduced nonheme iron absorption from couscous by 50% (16.5 vs. 33.1%; p < 0.01). In contrast, administration of 20 mg ascorbic acid increased nonheme iron absorption from couscous by more than 100% (66.8 vs. 33.1%; p < 0.001). Administration of ascorbic acid (20 mg) in a tea decoction (100 mg/ml) completely counteracted the inhibiting effect of tea and significantly improved the nonheme iron absorption from couscous (34 vs. 33% in the control group; NS). The same effect was shown when 10 mg ascorbic acid was added to the tea decoction; however, 5 mg ascorbic acid was not able to overcome the inhibitory effect of tea on nonheme iron absorption from couscous (33.1 vs. 19.4%; p < 0.01). Our findings demonstrate that a molar ratio of ascorbic acid and tea equal or superior to 0.25 or 0.50 is necessary to overcome the inhibitory effect in rats of tea prepared under Tunisian circumstances. In relation to human nutrition, for Tunisians who regularly drink tea, we suggest a much greater amount of ascorbic acid than that normally recommended for normal subjects.

Increase of weakly acidic gas esophagopharyngeal reflux (EPR) and swallowing-induced acidic/weakly acidic EPR in patients with chronic cough responding to proton pump inhibitors.

PubMed

Kawamura, O; Shimoyama, Y; Hosaka, H; Kuribayashi, S; Maeda, M; Nagoshi, A; Zai, H; Kusano, M

2011-05-01

Gastro-esophageal reflux disease (GERD)-related chronic cough (CC) may have multifactorial causes. To clarify the characteristics of esophagopharyngeal reflux (EPR) events in CC patients whose cough was apparently influenced by gastro-esophageal reflux (GER), we studied patients with CC clearly responding to full-dose proton pump inhibitor (PPI) therapy (CC patients). Ten CC patients, 10 GERD patients, and 10 healthy controls underwent 24-h ambulatory pharyngo-esophageal impedance and pH monitoring. Weakly acidic reflux was defined as a decrease of pH by >1 unit with a nadir pH >4. In six CC patients, monitoring was repeated after 8 weeks of PPI therapy. The number of each EPR event and the symptom association probability (SAP) were calculated. Symptoms were evaluated by a validated GERD symptom questionnaire. Weakly acidic gas EPR and swallowing-induced acidic/weakly acidic EPR only occurred in CC patients, and the numbers of such events was significantly higher in the CC group than in the other two groups (P < 0.05, respectively). Symptom association probability analysis revealed a positive association between GER and cough in three CC patients. Proton pump inhibitor therapy abolished swallowing-induced acidic/weakly acidic EPR, reduced weakly acidic gas EPR, and improved symptoms (all P < 0.05). Most patients with CC responding to PPI therapy had weakly acidic gas EPR and swallowing-induced acidic/weakly acidic EPR. A direct effect of acidic mist or liquid refluxing into the pharynx may contribute to chronic cough, while cough may also arise indirectly from reflux via a vago-vagal reflex in some patients. © 2011 Blackwell Publishing Ltd.

A search for intervening HI absorption

NASA Astrophysics Data System (ADS)

Reeves, Sarah N.; Sadler, Elaine M.; Allison, James R.; Koribalski, Baerbel S.; Curran, Stephen J.

2013-03-01

HI absorption-line studies provide a unique probe of the gas distribution and kinematics in galaxies well beyond the local universe (z ≳ 0.3). HI absorption-line surveys with next-generation radio telescopes will provide the first large-scale studies of HI in a redshift regime which is poorly understood. However, we currently lack the understanding to infer galaxy properties from absorption-line observations alone. To address this issue, we are conducting a search for intervening HI absorption in a sample of 20 nearby galaxies. Our aim is to investigate how the detection rate varies with distance from the galaxy. We target sight-lines to bright continuum sources, which intercept known gas-rich galaxies, selected from the HIPASS Bright Galaxy Catalogue (Koribalski et al. 2004). In our pilot sample, six galaxies with impact parameters < 20 kpc, we do not detect any absorption lines - although all are detected in 21cm emission. This indicates that an absorption non-detection cannot simply be interpreted as an absence of neutral gas - see Fig. 1. Our detection rate is low compared to previous surveys e.g. Gupta et al. (2010). This is, at least partially, due to the high resolution of the observations reducing the flux of the background source, which will also be an issue in future surveys, such as ASKAP-FLASH.

Evaluation of gas cooling for pressurized phosphoric acid fuel cell stacks

NASA Technical Reports Server (NTRS)

Farooque, M.; Skok, A. J.; Maru, H. C.; Kothmann, R. E.; Harry, R. W.

1983-01-01

Gas cooling is a more reliable, less expensive and a more simple alternative to conventional liquid cooling for heat removal from the phosphoric acid fuel cell (PAFC). The feasibility of gas cooling has already been demonstrated in atmospheric pressure stacks. This paper presents theoretical and experimental investigation of gas cooling for pressurized PAFC. Two approaches to gas cooling, Distributed Gas Cooling (DIGAS) and Separated Gas Cooling (SGC) were considered, and a theoretical comparison on the basis of cell performance indicated SGC to be superior to DIGAS. The feasibility of SGC was experimentally demonstrated by operating a 45-cell stack for 700 hours at pressure, and determining thermal response and the effect of other related parameters.

Do we still need to collect stool? Evaluation of visualized fatty acid absorption: experimental studies using rats.

PubMed

Chiba, T; Ohi, R

1998-01-01

Short-gut syndrome is likely to impair enteric fat utilization. This study was undertaken to develop a clinical test of lipid absorption without fecal collection. The absorption of enterally fed radioactive long-chain fatty acid, beta-methyl-p-(123I)-iodophenylpentadecanoic acid was investigated with continuous chyle collection in rats. The changes in excretion and time-dependent biodistribution of radioactivity of the enterally fed agent were assessed in normal control animals. Similarly, sequential urinary excretion and biodistribution were studied along with scintigraphy using sham-operated and short-gut animals. Approximately 64% of the enterally fed radioactivity was recovered in the collected chyle (24 hours). A comparison of normal control, sham-operated, and short-gut animals showed significantly less urinary and greater fecal excretions of radioactivity in short-gut animals. With the use of sequential scintigraphy, the small intestine, whole-body soft tissues, and urinary bladder were well visualized in sham-operated animals, whereas the large intestine and feces were demonstrated earlier in short-gut animals. Our results suggest that enteral feeding of the agent might be feasible for determining lipid absorption from the the dynamic changes of radioactivity in visualized abdominal organs and in urine.

Lotus Seed Resistant Starch Regulates Gut Microbiota and Increases Short-Chain Fatty Acids Production and Mineral Absorption in Mice.

PubMed

Zeng, Hongliang; Huang, Cancan; Lin, Shan; Zheng, Mingjing; Chen, Chuanjie; Zheng, Baodong; Zhang, Yi

2017-10-25

Lotus seed resistant starch, known as resistant starch type 3 (LRS3), was orally administered to mice to investigate its effects on the gut microbiota, short-chain fatty acids (SCFAs) production, and mineral absorption. The results showed that mice fed LRS3 displayed a lower level of gut bacterial diversity than other groups. The numbers of starch-utilizing and butyrate-producing bacteria, such as Lactobacillus and Bifidobacterium and Lachnospiraceae, Ruminococcaceae, and Clostridium, respectively, in mice increased after the administration of medium and high doses of LRS3, while those of Rikenellaceae and Porphyromonadaceae decreased. Furthermore, SCFAs and lactic acid in mice feces were affected by LRS3, and lactate was fermented to butyrate by gut microbiota. LRS3 enhanced the intestinal absorption of calcium, magnesium, and iron, and this was dependent on the type and concentration of SCFAs, especially butyrate. Thus, LRS3 promoted the production of SCFAs and mineral absorption by regulating gut microbiota in mice.

Conversion of laser energy to gas kinetic energy

NASA Technical Reports Server (NTRS)

Caledonia, G. E.

1975-01-01

Techniques for the gas phase absorption of laser radiation for conversion to gas kinetic energy are discussed. Absorption by inverse Bremsstrahlung, in which laser energy is converted at a gas kinetic rate in a spectrally continuous process, is briefly described, and absorption by molecular vibrational rotation bands is discussed at length. High pressure absorption is proposed as a means of minimizing gas bleaching and dissociation, the major disadvantages of the molecular absorption process. A band model is presented for predicting the molecular absorption spectra in the high pressure absorption region and is applied to the CO molecule. Use of a rare gas seeded with Fe(CO)5 for converting vibrational modes to translation modes is described.

Gas absorption/desorption temperature-differential engine

NASA Technical Reports Server (NTRS)

Miller, C. G.

1981-01-01

Continuously operating compressor system converts 90 percent of gas-turbine plant energy to electricity. Conventional plants work in batch mode, operating at 40 percent efficiency. Compressor uses metal hydride matrix on outside of rotating drum to generate working gas, hydrogen. Rolling valve seals allow continuous work. During operation, gas is absorbed, releasing heat, and desorbed with heat gain. System conserves nuclear and fossil fuels, reducing powerplant capital and operating costs.

Heat and Mass Transfer of Ammonia Gas Absorption into Falling Liquid Film on a Horizontal Tube

NASA Astrophysics Data System (ADS)

Inoue, Norihiro; Yabuuchi, Hironori; Goto, Masao; Koyama, Shigeru

Heat and mass transfer coefficients during ammonia gas absorption into a falling liquid film formed by distilled water on a horizontal tube were obtained experimentally. The test absorber consists of 200 mm i.d., 600 mm long stainless steel shell, a 1 7.3 mm o.d., 14.9 mm i.d. stainless steel test tube with 600 mm working length mounted along the axis of shell, and a 12.7 mm o.d. pipe manifold of supplying the absorbent. In this paper, it was clear that heat and mass transfer coefficient could be enhanced by increasing the flow rate of absorbent and temperature difference between inlet absorbent and ammonia gas, also heat driven by the temperature difference have an effect on heat transfer of the fa1ling liquid film and mass transfer of vapor side. And the new correlation of heat transfer in dimensionless form was proposed by the temperature difference which was considered heat driven of vapor and liquid film side using a interface temperature of vapor and liquid phase. The new correlations of mass transfer on a interface of vapor and liquid phase in dimensionless form were proposed by using effect factors could be suppose from absorption phenomena.

Tailored Algorithm for Sensitivity Enhancement of Gas Concentration Sensors Based on Tunable Laser Absorption Spectroscopy.

PubMed

Vargas-Rodriguez, Everardo; Guzman-Chavez, Ana Dinora; Baeza-Serrato, Roberto

2018-06-04

In this work, a novel tailored algorithm to enhance the overall sensitivity of gas concentration sensors based on the Direct Absorption Tunable Laser Absorption Spectroscopy (DA-ATLAS) method is presented. By using this algorithm, the sensor sensitivity can be custom-designed to be quasi constant over a much larger dynamic range compared with that obtained by typical methods based on a single statistics feature of the sensor signal output (peak amplitude, area under the curve, mean or RMS). Additionally, it is shown that with our algorithm, an optimal function can be tailored to get a quasi linear relationship between the concentration and some specific statistics features over a wider dynamic range. In order to test the viability of our algorithm, a basic C 2 H 2 sensor based on DA-ATLAS was implemented, and its experimental measurements support the simulated results provided by our algorithm.

Explaining the differential solubility of flue gas components in ionic liquids from first-principle calculations.

PubMed

Prasad, B Ram; Senapati, Sanjib

2009-04-09

Flue gas is greatly responsible for acid rain formation and global warming. New generation ionic liquids (ILs) have potential in controlling the flue gas emissions, as they acquire high absorptivity for the component gases SO(2), CO(2), etc. The association of the IL-gas interactions to the absorptivity of gas molecules in ILs is, however, poorly understood. In this paper, we present a molecular level description of the interactions of ILs with SO(2), CO(2), and N(2) and show its implications to the differential gas solubility. Our results indicate that the IL anion-gas interactions play a key role in deciding the gas solubility in ILs, particularly for polar gases such as SO(2). On the other hand, regular solution assumption applies to N(2) solubility. In accordance with the previous theoretical and experimental findings, our results also imply that the IL anions dominate the interactions with gas molecules while the cations play a secondary role and the underlying fluid structures of the ILs remain unperturbed by the addition of gas molecules.

Abundances of O, Mg, S, Cr, Mn, Ti, NI and Zn from absorption lines of neutral gas in the Large Magellanic Cloud in front of R136

NASA Astrophysics Data System (ADS)

de Boer, K. S.; Fitzpatrick, E. L.; Savage, B. D.

1985-11-01

The authors have searched six high-dispersion IUE spectra of R136 for weak absorption lines of C I, O I, Mg I, Mg II, Si I, Si II, P I, Cl I, Cr II, Mn II, Fe I, Ni II, Zn II, CO and C2. The absorption detected is from neutral gas in front of the 30 Doradus H II region. For the first time abundances of Mg, Cr, Mn, Ti, Ni, and Zn are determined for an extragalactic system. The LMC abundances from the absorption lines are a factor of 2 to 3 below those of the Milky Way, in agreement with general results from emission line studies. The density and temperature of the neutral gas are estimates from the observed excitation and ionization at approximately n(H) = 300 cm-3 and T = 100K, implying a gas pressure of about 3×104cm-3K.

Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

NASA Astrophysics Data System (ADS)

Pak, A.; Dewald, E. L.; Landen, O. L.; Milovich, J.; Strozzi, D. J.; Berzak Hopkins, L. F.; Bradley, D. K.; Divol, L.; Ho, D. D.; MacKinnon, A. J.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moore, A. S.; Schneider, M. B.; Town, R. P. J.; Hsing, W. W.; Edwards, M. J.

2015-12-01

Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.

Inhibition of methane and natural gas hydrate formation by altering the structure of water with amino acids.

PubMed

Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Cho, Seong Jun; Lee, Ju Dong; Lee, Kun-Hong

2016-08-16

Natural gas hydrates are solid hydrogen-bonded water crystals containing small molecular gases. The amount of natural gas stored as hydrates in permafrost and ocean sediments is twice that of all other fossil fuels combined. However, hydrate blockages also hinder oil/gas pipeline transportation, and, despite their huge potential as energy sources, our insufficient understanding of hydrates has limited their extraction. Here, we report how the presence of amino acids in water induces changes in its structure and thus interrupts the formation of methane and natural gas hydrates. The perturbation of the structure of water by amino acids and the resulting selective inhibition of hydrate cage formation were observed directly. A strong correlation was found between the inhibition efficiencies of amino acids and their physicochemical properties, which demonstrates the importance of their direct interactions with water and the resulting dissolution environment. The inhibition of methane and natural gas hydrate formation by amino acids has the potential to be highly beneficial in practical applications such as hydrate exploitation, oil/gas transportation, and flow assurance. Further, the interactions between amino acids and water are essential to the equilibria and dynamics of many physical, chemical, biological, and environmental processes.

Inhibition of methane and natural gas hydrate formation by altering the structure of water with amino acids

PubMed Central

Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Cho, Seong Jun; Lee, Ju Dong; Lee, Kun-Hong

2016-01-01

Natural gas hydrates are solid hydrogen-bonded water crystals containing small molecular gases. The amount of natural gas stored as hydrates in permafrost and ocean sediments is twice that of all other fossil fuels combined. However, hydrate blockages also hinder oil/gas pipeline transportation, and, despite their huge potential as energy sources, our insufficient understanding of hydrates has limited their extraction. Here, we report how the presence of amino acids in water induces changes in its structure and thus interrupts the formation of methane and natural gas hydrates. The perturbation of the structure of water by amino acids and the resulting selective inhibition of hydrate cage formation were observed directly. A strong correlation was found between the inhibition efficiencies of amino acids and their physicochemical properties, which demonstrates the importance of their direct interactions with water and the resulting dissolution environment. The inhibition of methane and natural gas hydrate formation by amino acids has the potential to be highly beneficial in practical applications such as hydrate exploitation, oil/gas transportation, and flow assurance. Further, the interactions between amino acids and water are essential to the equilibria and dynamics of many physical, chemical, biological, and environmental processes. PMID:27526869

Inhibition of methane and natural gas hydrate formation by altering the structure of water with amino acids

NASA Astrophysics Data System (ADS)

Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Cho, Seong Jun; Lee, Ju Dong; Lee, Kun-Hong

2016-08-01

Natural gas hydrates are solid hydrogen-bonded water crystals containing small molecular gases. The amount of natural gas stored as hydrates in permafrost and ocean sediments is twice that of all other fossil fuels combined. However, hydrate blockages also hinder oil/gas pipeline transportation, and, despite their huge potential as energy sources, our insufficient understanding of hydrates has limited their extraction. Here, we report how the presence of amino acids in water induces changes in its structure and thus interrupts the formation of methane and natural gas hydrates. The perturbation of the structure of water by amino acids and the resulting selective inhibition of hydrate cage formation were observed directly. A strong correlation was found between the inhibition efficiencies of amino acids and their physicochemical properties, which demonstrates the importance of their direct interactions with water and the resulting dissolution environment. The inhibition of methane and natural gas hydrate formation by amino acids has the potential to be highly beneficial in practical applications such as hydrate exploitation, oil/gas transportation, and flow assurance. Further, the interactions between amino acids and water are essential to the equilibria and dynamics of many physical, chemical, biological, and environmental processes.

High-quality electromagnetically-induced absorption resonances in a buffer-gas-filled vapour cell

NASA Astrophysics Data System (ADS)

Brazhnikov, D. V.; Ignatovich, S. M.; Vishnyakov, V. I.; Skvortsov, M. N.; Andreeva, Ch; Entin, V. M.; Ryabtsev, I. I.

2018-02-01

Magneto-optical subnatural-linewidth resonances of electromagnetically-induced absorption (EIA) in an alkali vapour cell have been experimentally studied. The observation configuration includes using two counter-propagating pumps and probe light waves with mutually orthogonal linear polarizations, exciting an open optical transition in the 87Rb D 1 line in the presence of argon buffer gas. The EIA signals registered in a probe-wave transmission reach an unprecedented contrast of about 135% with respect to the wide ‘Doppler’ absorption pedestal and 29% with respect to the level of background transmission signal. These contrast values correspond to a relatively small resonance full width at half maximum of about 7.2 mG (5.2 kHz). The width of the narrowest EIA resonance observed is about 2.1 mG (1.5 kHz). To our knowledge, such a large relative contrast at the kHz-width is the record result for EIA resonances. In general, the work has experimentally proved that the magneto-optical scheme used has very good prospects for various quantum technologies (quantum sensors of weak magnetic fields, optical switches and other photonic elements).

High-Speed Multiplexed Spatiotemporally Resolved Measurements of Exhaust Gas Recirculation Dynamics in a Multi-Cylinder Engine Using Laser Absorption Spectroscopy.

PubMed

Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

2016-04-01

The need for more environmentally friendly and efficient energy conversion is of paramount importance in developing and designing next-generation internal combustion (IC) engines for transportation applications. One effective solution to reducing emissions of mono-nitrogen oxides (NOx) is exhaust gas recirculation (EGR), which has been widely implemented in modern vehicles. However, cylinder-to-cylinder and cycle-to-cycle variations in the charge-gas uniformity can be a major barrier to optimum EGR implementation on multi-cylinder engines, and can limit performance, stability, and efficiency. Precise knowledge and fine control over the EGR system is therefore crucial, particularly for optimizing advanced engine concepts such as reactivity controlled compression ignition (RCCI). An absorption-based laser diagnostic was developed to study spatiotemporal charge-gas distributions in an IC engine intake manifold in real-time. The laser was tuned to an absorption band of carbon dioxide (CO2), a standard exhaust-gas marker, near 2.7 µm. The sensor was capable of probing four separate measurement locations simultaneously, and independently analyzing EGR fraction at speeds of 5 kHz (1.2 crank-angle degree (CAD) at 1 k RPM) or faster with high accuracy. The probes were used to study spatiotemporal EGR non-uniformities in the intake manifold and ultimately promote the development of more efficient and higher performance engines. © The Author(s) 2016.

Influence of polarity of solvents on IR absorption and Raman spectra of ascorbic acid

NASA Astrophysics Data System (ADS)

Kutsenko, S. A.; Danyaeva, Y. S.; Maximova, S. V.

2018-04-01

The results of numerical calculations of IR absorption and Raman spectra of ascorbic acid in polar and nonpolar solutions are presented. The dependence of the change in the total energy and the dipole moment of the molecule on the characteristics of the solvents was investigated using the two solvation models. Spectral bands and the corresponding structural groups of the molecule are found, the characteristics of which are most vulnerable to solvents.

In vitro prediction of gastrointestinal absorption of novel β-hydroxy-β-arylalkanoic acids using PAMPA technique.

PubMed

Savić, Jelena; Dobričić, Vladimir; Nikolic, Katarina; Vladimirov, Sote; Dilber, Sanda; Brborić, Jasmina

2017-03-30

Prediction of gastrointestinal absorption of thirteen newly synthesized β-hydroxy-β-arylalkanoic acids (HAA) and ibuprofen was performed using PAMPA test. The highest values of PAMPA parameters (%T and P app ) were calculated for 1C, 1B and 2C and these parameters were significantly lower in comparison to ibuprofen. QSPR analysis was performed in order to identify molecular descriptors with the highest influence on %T and -logP app and to create models which could be used for the design of novel HAA with improved gastrointestinal absorption. Obtained results indicate that introduction of branched side chain, as well as introduction of substituents on one phenyl ring (which disturb symmetry of the molecule) could have positive impact on gastrointestinal absorption. On the basis of these results, six novel HAA were designed and PAMPA parameters %T and -logP app were predicted by use of selected QSPR models. Designed derivatives should have better gastrointestinal absorption than HAA tested in this study. Copyright © 2017 Elsevier B.V. All rights reserved.

The influence of the sennosides on absorption of glycyrrhetic acid in rats.

PubMed

Mizuhara, Yasuharu; Takizawa, Yukiho; Ishihara, Kazuhisa; Asano, Takayuki; Kushida, Hirotaka; Morota, Takashi; Kase, Yoshio; Takeda, Shuichi; Aburada, Masaki; Nomura, Masaaki; Yokogawa, Koichi

2005-10-01

In the course of our clinical studies of Kampo medicine (traditional Japanese medicines), we observed the pharmacokinetic interactions between two herbs. When Onpito (TJ-8117, Kampo medicine) containing licorice and rhubarb was administered orally to human subjects, we observed that the AUC(0-lim) and Cmax of glycyrrhetic acid (GA) in plasma were lower than those treated with other Kampo medicines containing licorice. In this study, we demonstrate the pharmacokinetic interactions of GA derived from glycyrrhizinic acid (GL) in licorice and anthraquinones derived from rhubarb. To our knowledge, this is the first report to investigate the pharmacokinetic interactions between two herbs. When GL was orally co-administrated to rats with a non-effective dose of sennoside A having purgative activity, the AUC(0-lim) and Cmax of GA decreased. In addition, sennoside A did not affect the metabolism of GL by the intestinal bacteria in vitro. In the examination using an in situ loop of rat colon, the remaining ratio of GA rose drastically by the co-administration of sennoside A, sennidin A and rhein. Observed inhibition activity of these anthraquinones on GA absorption depended on the concentration of the components added. The maximum inhibition ratio was approximately 75% by rhein, 60% by sennoside A and 25% by sennidin A. We conclude that the decrease of the pharmacokinetic parameters of GA in human plasma observed in the clinical study of TJ-8117 is attributable to an interactive action of absorption from the intestinal tract by anthraquinones contained in or derived from rhubarb.

Discovery of Hα Absorption in the Unusual Broad Absorption Line Quasar SDSS J083942.11+380526.3

NASA Astrophysics Data System (ADS)

Aoki, Kentaro; Iwata, Ikuru; Ohta, Kouji; Ando, Masataka; Akiyama, Masayuki; Tamura, Naoyuki

2006-11-01

We discovered Hα absorption in the broad Hα emission line of an unusual broad absorption line quasar, SDSS J083942.11+380526.3, at z=2.318, through near-infrared spectroscopy with the Cooled Infrared Spectrograph and Camera for OHS (CISCO) on the Subaru telescope. The presence of nonstellar Hα absorption is known only in the Seyfert galaxy NGC 4151 to date; thus, our discovery is the first case for quasars. The Hα absorption line is blueshifted by 520 km s-1 relative to the Hα emission line, and its redshift almost coincides with those of UV low-ionization metal absorption lines. The width of the Hα absorption (~340 km s-1) is similar to those of the UV low-ionization absorption lines. These facts suggest that the Hα and low-ionization metal absorption lines are produced by the same low-ionization gas, which has a substantial amount of neutral gas. The column density of the neutral hydrogen is estimated to be ~1018 cm-2 by assuming a gas temperature of 10,000 K from the analysis of the curve of growth. The continuum spectrum is reproduced by a reddened [E(B-V)~0.15 mag for the SMC-like reddening law] composite quasar spectrum. Furthermore, the UV spectrum of SDSS J083942.11+380526.3 shows a remarkable similarity to that of NGC 4151 in its low state, suggesting that the physical condition of the absorber in SDSS J083942.11+380526.3 is similar to that of NGC 4151 in the low state. As proposed for NGC 4151, SDSS J083942.11+380526.3 may also be seen through the edge of the obscuring torus. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Effect of 1,4-cyclohexanediol on percutaneous absorption and penetration of azelaic acid.

PubMed

Li, Nan; Su, Qian; Tan, Fengping; Zhang, Jerry

2010-03-15

The objective of this study is to investigate the effect of 1,4-cyclohexanediol as a retardant on the percutaneous absorption and penetration of azelaic acid. Hairless rat skin was mounted on Franz diffusion cells and treated with topical formulations containing solubilized azelaic acid with and without 1,4-cyclohexanediol. The skin was separated into stratum corneum and the deeper skin layers. The azelaic acid collected in receptor medium and each layer at the end of each time point was extracted and quantified. A significant decrease in flux across the skin suggests a penetration retardation effect of 1,4-cyclohexanediol (42.50 microg/cm(2)/h in the presence of vs. 76.25 microg/cm(2)/h in the absence of) at active loading level of 1.13 mg/cm(2). The penetration retardation effect was also observed at higher active loading level (2.82 mg/cm(2)). Furthermore, presence of 1,4-cyclohexanediol in the topical formulation did not reduce the skin and epidermal retention of azelaic acid, suggesting its potential use in the development of superior topical formation for reducing potential systematic side effect while maintaining therapeutic efficiency. 2009 Elsevier B.V. All rights reserved.

Sustainable synthesis of aldehydes, ketones or acids from neat alcohols using nitrogen dioxide gas, and related reactions.

PubMed

Naimi-Jamal, M Reza; Hamzeali, Hamideh; Mokhtari, Javad; Boy, Jürgen; Kaupp, Gerd

2009-01-01

Benzylic alcohols are quantitatively oxidized by gaseous nitrogen dioxide to give pure aromatic aldehydes. The reaction gas mixtures are transformed to nitric acid, which renders the processes free of waste. The exothermic gas-liquid or gas-solid reactions profit from the solubility of nitrogen dioxide in the neat benzylic alcohols. The acid formed impedes further oxidation of the benzaldehydes. The neat isolated benzaldehydes and nitrogen dioxide quantitatively give the benzoic acids. Solid long-chain primary alcohols are directly and quantitatively oxidized with nitrogen dioxide gas to give the fatty acids in the solid state. The oxidations with ubiquitous nitrogen dioxide are extended to solid heterocyclic thioamides, which gives disulfides, and to diphenylamine, which gives tetraphenylhydrazine. These sustainable (green) specific oxidation procedures produce no dangerous residues from the oxidizing agent or from auxiliaries.

Coronal gas in the galaxy. II. A statistical analysis of O VI absorptions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenkins, E.B.

Results from the survey of interstellar O VI by Jenkins and by Jenkins and Meloy are analyzed to synthesize a global description of the properties of the coronal gas. Tests for correlations of column densities or velocities with properties of the target stars showed no evidence for a circumstellar origin for the absorption lines. An overall average density n (O VI) =2.8 x 10/sup -8/ cm/sup -3/ was found in the galactic plane, with a decrease which approximately follows exp (-z/300 pc) away from the plane.Fluctuations in column densities over various lines of sight suggest that existence of six hotmore » gas regions kpc/sup -/1, randomly distributed in space, each with an O VI column density of about 10/sup 13/ cm/sup -2/. These regions account for an average density n (O VI) =2.1 x 10/sup -8/ cm/sup -3/; the remaining 7 x 10/sup -9/ cm/sup -3/ is produced by more sparsely distributed but thicker parcels of hot gas which are seen toward 10% of the stars. The statistics of radial velocity centroids and widths support the interpretation of distinct domains; each region has an internal velocity dispersion consistent with a Doppler broadening of a plasma at T> or approx. =2 x 10/sup 5/ K (near the characteristic temperature for a maximum concentration of O VI in collisional equilibrium), while the regions themselves move about with a dispersion of radial velocities equal to 26 km s/sup -1/. Systematic motions of gas away from the galactic plane could not be seen, however.Excursions from the normal O VI per unit distance have no perceptible anicorrelation with deviations in reddening by cool interstellar coulds: a fact which suggests that the average filling factor of O VI gas is less than 20% if coronal gas really displaces the cooler material and does not have large variations in density and temperature.« less

Advances in Methane Isotope Measurements via Direct Absorption Spectroscopy with Applications to Oil and Gas Source Characterization

NASA Astrophysics Data System (ADS)

Yacovitch, T. I.; Herndon, S. C.; Roscioli, J. R.; Petron, G.; Shorter, J. H.; Jervis, D.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Kolb, C. E., Jr.

2015-12-01

Instrumental developments in the measurement of multiple isotopes of methane (12CH4, 13CH4 and 12CH3D) are presented. A first generation 8-micron instrument quantifies 12CH4 and 13CH4 at a 1-second rate via tunable infrared direct absorption spectroscopy (TILDAS). A second generation instrument uses two 3-micron intraband cascade lasers in an Aerodyne dual laser chassis for simultaneous measurement of 12CH4, 13CH4 and 12CH3D. Sensitivity and noise performance improvements are examined. The isotopic signature of methane provides valuable information for emission source identification of this greenhouse gas. A first generation spectrometer has been deployed in the field on a mobile laboratory along with a sophisticated 4-tank calibration system. Calibrations are done on an agressive schedule, allowing for the correction of measured isotope ratios to an absolute isotope scale. Distinct isotopic signatures are found for a number of emission sources in the Denver-Julesburg Basin: oil and gas gathering stations, compressor stations and processing plants; a municipal landfill, and dairy/cattle operations. The isotopic signatures are compared with measured ethane/methane ratios. These direct absorption measurements have larger uncertainties than samples measured via gas chromatography-mass spectrometry, but have several advantages over canister sampling methods: individual sources of short duration are easier to isolate; calibrated isotope ratio results are available immediately; replicate measurements on a single source are easily performed; and the number of sources sampled is not limited by canister availability and processing time.

Absorption, fluorescence, and acid-base equilibria of rhodamines in micellar media of sodium dodecyl sulfate

NASA Astrophysics Data System (ADS)

Obukhova, Elena N.; Mchedlov-Petrossyan, Nikolay O.; Vodolazkaya, Natalya A.; Patsenker, Leonid D.; Doroshenko, Andrey O.; Marynin, Andriy I.; Krasovitskii, Boris M.

2017-01-01

Rhodamine dyes are widely used as molecular probes in different fields of science. The aim of this paper was to ascertain to what extent the structural peculiarities of the compounds influence their absorption, emission, and acid-base properties under unified conditions. The acid-base dissociation (HR+ ⇄ R + H+) of a series of rhodamine dyes was studied in sodium n-dodecylsulfate micellar solutions. In this media, the form R exists as a zwitterion R±. The indices of apparent ionization constants of fifteen rhodamine cations HR+ with different substituents in the xanthene moiety vary within the range of pKaapp = 5.04 to 5.53. The distinct dependence of emission of rhodamines bound to micelles on pH of bulk water opens the possibility of using them as fluorescent interfacial acid-base indicators.

Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

PubMed

Svensson, Tomas; Lewander, Märta; Svanberg, Sune

2010-08-02

We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

[Absorption of Uranium with Tea Oil Tree Sawdust Modified by Succinic Acid].

PubMed

Zhang, Xiao-feng; Chen, Di-yun; Peng, Yan; Liu, Yong-sheng; Xiong, Xue-ying

2015-05-01

In order to explore how the modification of succinic acid improves the adsorption of tea oil tree sawdust for uranium, the tea oil tree sawdust was modified by succinic acid, after the pretreatments of crushing, screening, alkalization and acidification. Infrared analysis indicated carboxylic acid groups and ester groups were added to the sawdust after modification, and scanning electron microscope demonstrated after modification the appearance of tea oil tree sawdust was transferred from the structure like compact and straight stripped into the structure like loose and wrinkled leaves, which meant modification increased its inner pores. By the static experiments, effects of reaction time between adsorbent and solvent, dosage of adsorbent, temperature, pH value and initial concentration of uranium were investigated. The results showed that after the modification by succinic acid, the absorption rate of tea oil tree sawdust for uranium increased significantly by about 20% in 12.5 mg · L(-1) initial concentration uranium solution. Adsorption equilibrium was achieved within 180 min, and the kinetic data can be well described by the pseudo-second-order kinetic model. The experimental adsorption isotherm followed the Langmuir and Freundlich models. In addition, the maximum adsorption amounts of tea oil tree sawdust after modification calculated from Langmuir equation raised from 21.413 3 to 31.545 7 mg · g(-1) at 35°C and pH 4.0.

Combined experimental and computational investigation of the absorption spectra of E- and Z-cinnamic acids in solution: The peculiarity of Z-cinnamics.

PubMed

Salum, María L; Arroyo Mañez, Pau; Luque, F Javier; Erra-Balsells, Rosa

2015-07-01

Cinnamic acids are present in all kinds of plant tissues and hence in herbs and derived medicines, cosmetics and foods. The interest in their role in plants and their therapeutic applications has grown exponentially. Because of their molecular structure they can exist in E- and Z-forms, which are both found in plants. However, since only the E-forms are commercially available, very few in vitro and in vivo studies of the Z-form have been reported. In this work the physico-chemical properties of Z-cinnamic acids in solution have been examined by means of UV-absorption spectroscopy and high-level quantum mechanical computations. For each isomer similar absorption spectra were obtained in methanol and acetonitrile. However, distinct trends were found for Z- and E forms of cinnamic acids in water, where a higher hypsochromic shift of the Z-isomer relative to the E-form was observed. In general the wavelength of maximal absorption of the Z-form is dramatically blue shifted (-30 to -40 nm) to λ<280 nm, while a slightly blue shift of the absorption maxima for the corresponding E-form (+3 to -4 nm) was observed. This difference is associated with the non-planar, largely distorted, Z-structure and to the almost complete flat structure of the E-form. The results provide a basis for the study of functional and biotechnological roles of cinnamic acids and for the analysis of samples containing mixture of both geometric isomers. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pak, A.; Dewald, E. L.; Landen, O. L.

2015-12-15

Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are usedmore » to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.« less

Multi-component removal in flue gas by aqua ammonia

DOEpatents

Yeh, James T [Bethel Park, PA; Pennline, Henry W [Bethel Park, PA

2007-08-14

A new method for the removal of environmental compounds from gaseous streams, in particular, flue gas streams. The new method involves first oxidizing some or all of the acid anhydrides contained in the gas stream such as sulfur dioxide (SO.sub.2) and nitric oxide (NO) and nitrous oxide (N.sub.2O) to sulfur trioxide (SO.sub.3) and nitrogen dioxide (NO.sub.2). The gas stream is subsequently treated with aqua ammonia or ammonium hydroxide which captures the compounds via chemical absorption through acid-base or neutralization reactions. The products of the reactions can be collected as slurries, dewatered, and dried for use as fertilizers, or once the slurries have been dewatered, used directly as fertilizers. The ammonium hydroxide can be regenerated and recycled for use via thermal decomposition of ammonium bicarbonate, one of the products formed. There are alternative embodiments which entail stoichiometric scrubbing of nitrogen oxides and sulfur oxides with subsequent separate scrubbing of carbon dioxide.

Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

PubMed Central

Li, Yanan; Jiang, Han; Huang, Guangrong

2017-01-01

Iron (Fe) is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements. PMID:28617327

Ammonia gas sensing behavior of tanninsulfonic acid doped polyaniline-TiO₂ composite.

PubMed

Bairi, Venu Gopal; Bourdo, Shawn E; Sacre, Nicolas; Nair, Dev; Berry, Brian C; Biris, Alexandru S; Viswanathan, Tito

2015-10-16

A highly active tannin doped polyaniline-TiO₂ composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI)-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO₂ in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO₂. Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM) surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO₂ and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm) of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO₂ composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported.

Simultaneous absorption of CO2 and H2S into aqueous blends of N-methyldiethanolamine and diethanolamine.

PubMed

Mandald, Bishnupada; Bandyopadhyay, Shyamalendu S

2006-10-01

Removal of CO2 from gaseous streams by absorption with chemical reaction in the liquid phase is usually employed in industry as a method to retain atmospheric CO2 to combat the greenhouse effect. A broad spectrum of alkanolamines and, more recently, their mixtures are being employed for the removal of acid gases such as CO2, H2S, and COS from natural and industrial gas streams. In this research, simultaneous absorption of CO2 and H2S into aqueous blends of N-methyldiethanolamine and diethanolamine is studied theoretically and experimentally. The effect of contact time, temperature, and amine concentration on the rate of absorption and the selectivity were studied by absorption experiments in a wetted wall column at atmospheric pressure and constant feed gas ratio. The diffusion-reaction processes for CO2 and H2S mass transfer in blended amines are modeled according to Higbie's penetration theory with the assumption that all reactions are reversible. A rigorous parametric sensitivity test is done to quantify the effects of possible errors in the pertinent model parameters on the prediction accuracy of the absorption rates and enhancement factors. Model results based on the kinetics-equilibrium-mass transfer coupled model developed in this work are found to be in good agreement with the experimental results of rates of absorption of CO2 and H2S into (MDEA + DEA + H2O).

Indirect Gas Species Monitoring Using Tunable Diode Lasers

DOEpatents

Von Drasek, William A.; Saucedo, Victor M.

2005-02-22

A method for indirect gas species monitoring based on measurements of selected gas species is disclosed. In situ absorption measurements of combustion species are used for process control and optimization. The gas species accessible by near or mid-IR techniques are limited to species that absorb in this spectral region. The absorption strength is selected to be strong enough for the required sensitivity and is selected to be isolated from neighboring absorption transitions. By coupling the gas measurement with a software sensor gas, species not accessible from the near or mid-IR absorption measurement can be predicted.

Design and development of a probe-based multiplexed multi-species absorption spectroscopy sensor for characterizing transient gas-parameter distributions in the intake systems of I.C. engines

DOE PAGES

Jatana, Gurneesh; Geckler, Sam; Koeberlein, David; ...

2016-09-01

We designed and developed a 4-probe multiplexed multi-species absorption spectroscopy sensor system for gas property measurements on the intake side of commercial multi-cylinder internal-combustion (I.C.) engines; the resulting cycle- and cylinder-resolved concentration, temperature and pressure measurements are applicable for assessing spatial and temporal variations in the recirculated exhaust gas (EGR) distribution at various locations along the intake gas path, which in turn is relevant to assessing cylinder charge uniformity, control strategies, and CFD models. Furthermore, the diagnostic is based on absorption spectroscopy and includes an H 2O absorption system (utilizing a 1.39 m distributed feedback (DFB) diode laser) for measuringmore » gas temperature, pressure, and H 2O concentration, and a CO 2 absorption system (utilizing a 2.7 m DFB laser) for measuring CO 2 concentration. The various lasers, optical components and detectors were housed in an instrument box, and the 1.39- m and 2.7- m lasers were guided to and from the engine-mounted probes via optical fibers and hollow waveguides, respectively. The 5kHz measurement bandwidth allows for near-crank angle resolved measurements, with a resolution of 1.2 crank angle degrees at 1000 RPM. Our use of compact stainless steel measurement probes enables simultaneous multi-point measurements at various locations on the engine with minimal changes to the base engine hardware; in addition to resolving large-scale spatial variations via simultaneous multi-probe measurements, local spatial gradients can be resolved by translating individual probes. Along with details of various sensor design features and performance, we also demonstrate validation of the spectral parameters of the associated CO 2 absorption transitions using both a multi-pass heated cell and the sensor probes.« less

Differences in the intramolecular structure of structured oils do not affect pancreatic lipase activity in vitro or the absorption by rats of (n-3) fatty acids.

PubMed

Porsgaard, Trine; Xu, Xuebing; Göttsche, Jesper; Mu, Huiling

2005-07-01

The fatty acid composition and intramolecular structure of dietary triacylglycerols (TAGs) influence their absorption. We compared the in vitro pancreatic lipase activity and the lymphatic transport in rats of fish oil and 2 enzymatically interesterified oils containing 10:0 and (n-3) PUFAs of marine origin to investigate whether the positional distribution of fatty acids influenced the overall bioavailability of (n-3) PUFAs in the body. The structured oils had the (n-3) PUFA either mainly at the sn-1,3 position (LML, M = medium-chain fatty acid, L = long-chain fatty acid) or mainly at the sn-2 position (MLM). Oils were administered to lymph-cannulated rats and lymph was collected for 24 h. The fatty acid composition as well as the lipid class distribution of lymph samples was determined. In vitro pancreatic lipase activity was greater when fish oil was the substrate than when the structured oils were the substrates (P < 0.001 at 40 min). This was consistent with a greater 8-h recovery of total fatty acids from fish oil compared with the 2 structured oils (P < 0.05). The absorption profiles of MLM and LML in rats and their in vitro rates of lipase activity did not differ. This indicates that the absorption rate is highly influenced by the lipase activity, which in turn is affected by the fatty acid composition and intramolecular structure. The lipid class distribution in lymph collected from the 3 groups of rats did not differ. In conclusion, the intramolecular structure did not affect the overall absorption of (n-3) PUFAs.

Food Ingredients That Inhibit Cholesterol Absorption

PubMed Central

Jesch, Elliot D.; Carr, Timothy P.

2017-01-01

Cholesterol is a vital component of the human body. It stabilizes cell membranes and is the precursor of bile acids, vitamin D and steroid hormones. However, cholesterol accumulation in the bloodstream (hypercholesterolemia) can cause atherosclerotic plaques within artery walls, leading to heart attacks and strokes. The efficiency of cholesterol absorption in the small intestine is of great interest because human and animal studies have linked cholesterol absorption with plasma concentration of total and low density lipoprotein cholesterol. Cholesterol absorption is highly regulated and influenced by particular compounds in the food supply. Therefore, it is desirable to learn more about natural food components that inhibit cholesterol absorption so that food ingredients and dietary supplements can be developed for consumers who wish to manage their plasma cholesterol levels by non-pharmacological means. Food components thus far identified as inhibitors of cholesterol absorption include phytosterols, soluble fibers, phospholipids, and stearic acid. PMID:28702423

Organic absorption gas-fired residential heat pump

NASA Astrophysics Data System (ADS)

Murphy, K. P.

The development program of a system utilizing a new absorption pair, R133a (CF3CH2Cl) as the refigerant, and ETFE (ethyletra-hydrofurfury lether) as the absorber fluid, is described. A diagram of the basic configuration is shown. The cooling mode and the heating mode are discussed. Six units of an early hardware design were constructed and tested. Two of these units were placed in home heating service during the 1980-81 season. A market evaluation of the business potential of the absorption system was made, identifying location and size of the likely market for such a system. A performance simulation analysis was performed for seven cities in the US. From these, general characteristics of the areas having the greatest performance benefits were established.

A fast code for channel limb radiances with gas absorption and scattering in a spherical atmosphere

NASA Astrophysics Data System (ADS)

Eluszkiewicz, Janusz; Uymin, Gennady; Flittner, David; Cady-Pereira, Karen; Mlawer, Eli; Henderson, John; Moncet, Jean-Luc; Nehrkorn, Thomas; Wolff, Michael

2017-05-01

We present a radiative transfer code capable of accurately and rapidly computing channel limb radiances in the presence of gaseous absorption and scattering in a spherical atmosphere. The code has been prototyped for the Mars Climate Sounder measuring limb radiances in the thermal part of the spectrum (200-900 cm-1) where absorption by carbon dioxide and water vapor and absorption and scattering by dust and water ice particles are important. The code relies on three main components: 1) The Gauss Seidel Spherical Radiative Transfer Model (GSSRTM) for scattering, 2) The Planetary Line-By-Line Radiative Transfer Model (P-LBLRTM) for gas opacity, and 3) The Optimal Spectral Sampling (OSS) for selecting a limited number of spectral points to simulate channel radiances and thus achieving a substantial increase in speed. The accuracy of the code has been evaluated against brute-force line-by-line calculations performed on the NASA Pleiades supercomputer, with satisfactory results. Additional improvements in both accuracy and speed are attainable through incremental changes to the basic approach presented in this paper, which would further support the use of this code for real-time retrievals and data assimilation. Both newly developed codes, GSSRTM/OSS for MCS and P-LBLRTM, are available for additional testing and user feedback.

Pepsi® or Coke®? Influence of acid on dasatinib absorption.

PubMed

Knoebel, Randall W; Larson, Richard A

2018-03-01

Dasatinib is a second generation ABL kinase inhibitor used in the management of chronic myeloid leukemia or Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL). Dasatinib's bioavailability is highly dependent on gastric pH. When proton-pump inhibitors (PPIs) are co-administered with dasatinib, absorption is significantly reduced. Cola intake at the time of drug administration has been demonstrated to lead to relevant increases in the bioavailability for other acid labile drugs during PPI treatment. This manuscript reviews the relevant literature supporting a strategy of temporarily lowering the gastric pH with a carbonated beverage at the time of drug administration. The use of cola provides an easy to implement way to significantly improve dasatinib bioavailability, especially during concomitant use of a PPI.

Conversion of laser energy to gas kinetic energy

NASA Technical Reports Server (NTRS)

Caledonia, G. E.

1976-01-01

Techniques for the gas phase absorption of laser radiation for ultimate conversion to gas kinetic energy are discussed. Particular emphasis is placed on absorption by the vibration rotation bands of diatomic molecules at high pressures. This high pressure absorption appears to offer efficient conversion of laser energy to gas translational energy. Bleaching and chemical effects are minimized and the variation of the total absorption coefficient with temperature is minimal.

The Scaled SLW model of gas radiation in non-uniform media based on Planck-weighted moments of gas absorption cross-section

NASA Astrophysics Data System (ADS)

Solovjov, Vladimir P.; Andre, Frederic; Lemonnier, Denis; Webb, Brent W.

2018-02-01

The Scaled SLW model for prediction of radiation transfer in non-uniform gaseous media is presented. The paper considers a new approach for construction of a Scaled SLW model. In order to maintain the SLW method as a simple and computationally efficient engineering method special attention is paid to explicit non-iterative methods of calculation of the scaling coefficient. The moments of gas absorption cross-section weighted by the Planck blackbody emissive power (in particular, the first moment - Planck mean, and first inverse moment - Rosseland mean) are used as the total characteristics of the absorption spectrum to be preserved by scaling. Generalized SLW modelling using these moments including both discrete gray gases and the continuous formulation is presented. Application of line-by-line look-up table for corresponding ALBDF and inverse ALBDF distribution functions (such that no solution of implicit equations is needed) ensures that the method is flexible and efficient. Predictions for radiative transfer using the Scaled SLW model are compared to line-by-line benchmark solutions, and predictions using the Rank Correlated SLW model and SLW Reference Approach. Conclusions and recommendations regarding application of the Scaled SLW model are made.

Measurements of water molecule density by tunable diode laser absorption spectroscopy in dielectric barrier discharges with gas-water interface

NASA Astrophysics Data System (ADS)

Tachibana, Kunihide; Nakamura, Toshihiro; Kawasaki, Mitsuo; Morita, Tatsuo; Umekawa, Toyofumi; Kawasaki, Masahiro

2018-01-01

We measured water molecule (H2O) density by tunable diode-laser absorption spectroscopy (TDLAS) for applications in dielectric barrier discharges (DBDs) with a gas-water interface. First, the effects of water temperature and presence of gas flow were tested using a Petri dish filled with water and a gas injection nozzle. Second, the TDLAS system was applied to the measurements of H2O density in two types of DBDs; one was a normal (non-inverted) type with a dielectric-covered electrode above a water-filled counter electrode and the other was an inverted type with a water-suspending mesh electrode above a dielectric-covered counter electrode. The H2O density in the normal DBD was close to the density estimated from the saturated vapor pressure, whereas the density in the inverted DBD was about half of that in the former type. The difference is attributed to the upward gas flow in the latter type, that pushes the water molecules up towards the gas-water interface.

Improving intestinal absorption and oral bioavailability of curcumin via taurocholic acid-modified nanostructured lipid carriers.

PubMed

Tian, Cihui; Asghar, Sajid; Wu, Yifan; Chen, Zhipeng; Jin, Xin; Yin, Lining; Huang, Lin; Ping, Qineng; Xiao, Yanyu

2017-01-01

The expression of multiple receptors on intestinal epithelial cells enables an actively targeted carrier to significantly enhance the oral delivery of payloads. Conjugating the receptors' ligands on the surfaces of a particulate-delivery system allows site-specific targeting. Here, we used taurocholic acid (TCA) as a ligand for uptake of nanostructured lipid carriers (NLCs) mediated by a bile-acid transporter to improve oral bioavailability of curcumin (Cur). First, synthesis of TCA-polyethylene glycol 100-monostearate (S100-TCA) was carried out. Then, the physical and chemical properties of S100-TCA-modified Cur-loaded NLCs (Cur-TCA NLCs) with varying levels of S100-TCA modifications were investigated. Small particle size (<150 nm), high drug encapsulation (>90%), drug loading (about 3%), negative ζ-potential (-7 to -3 mV), and sustained release were obtained. In situ intestinal perfusion studies demonstrated improved absorption rate and permeability coefficient of Cur-TCA NLCs. Depending on the degree of modification, Cur-TCA NLCs displayed about a five- to 15-fold higher area under the curve in rats after oral administration than unmodified Cur NLCs, which established that the addition of S100-TCA to the NLCs boosted absorption of Cur. Further investigations of TCA NLCs might reveal a bright future for effective oral delivery of poorly bioavailable drugs.

Isothermal absorption of soluble gases by atmospheric nanoaerosols

NASA Astrophysics Data System (ADS)

Elperin, T.; Fominykh, A.; Krasovitov, B.; Lushnikov, A.

2013-01-01

We investigate mass transfer during the isothermal absorption of atmospheric trace soluble gases by a single droplet whose size is comparable to the molecular mean free path in air at normal conditions. It is assumed that the trace reactant diffuses to the droplet surface and then reacts with the substances inside the droplet according to the first-order rate law. Our analysis applies a flux-matching theory of transport processes in gases and assumes constant thermophysical properties of the gases and liquids. We derive an integral equation of Volterra type for the transient molecular flux density to a liquid droplet and solve it numerically. Numerical calculations are performed for absorption of sulfur dioxide (SO2), dinitrogen trioxide (N2O3), and chlorine (Cl2) by liquid nanoaerosols accompanied by chemical dissociation reaction. It is shown that during gas absorption by nanoaerosols, the kinetic effects play a significant role, and neglecting kinetic effects leads to a significant overestimation of the soluble gas flux into a droplet during the entire period of gas absorption.

Isothermal absorption of soluble gases by atmospheric nanoaerosols.

PubMed

Elperin, T; Fominykh, A; Krasovitov, B; Lushnikov, A

2013-01-01

We investigate mass transfer during the isothermal absorption of atmospheric trace soluble gases by a single droplet whose size is comparable to the molecular mean free path in air at normal conditions. It is assumed that the trace reactant diffuses to the droplet surface and then reacts with the substances inside the droplet according to the first-order rate law. Our analysis applies a flux-matching theory of transport processes in gases and assumes constant thermophysical properties of the gases and liquids. We derive an integral equation of Volterra type for the transient molecular flux density to a liquid droplet and solve it numerically. Numerical calculations are performed for absorption of sulfur dioxide (SO(2)), dinitrogen trioxide (N(2)O(3)), and chlorine (Cl(2)) by liquid nanoaerosols accompanied by chemical dissociation reaction. It is shown that during gas absorption by nanoaerosols, the kinetic effects play a significant role, and neglecting kinetic effects leads to a significant overestimation of the soluble gas flux into a droplet during the entire period of gas absorption.

Investigation of Gas-Sensing Property of Acid-Deposited Polyaniline Thin-Film Sensors for Detecting H2S and SO2

PubMed Central

Dong, Xingchen; Zhang, Xiaoxing; Wu, Xiaoqing; Cui, Hao; Chen, Dachang

2016-01-01

Latent insulation defects introduced in manufacturing process of gas-insulated switchgears can lead to partial discharge during long-time operation, even to insulation fault if partial discharge develops further. Monitoring of decomposed components of SF6, insulating medium of gas-insulated switchgear, is a feasible method of early-warning to avoid the occurrence of sudden fault. Polyaniline thin-film with protonic acid deposited possesses wide application prospects in the gas-sensing field. Polyaniline thin-film sensors with only sulfosalicylic acid deposited and with both hydrochloric acid and sulfosalicylic acid deposited were prepared by chemical oxidative polymerization method. Gas-sensing experiment was carried out to test properties of new sensors when exposed to H2S and SO2, two decomposed products of SF6 under discharge. The gas-sensing properties of these two sensors were compared with that of a hydrochloric acid deposited sensor. Results show that the hydrochloric acid and sulfosalicylic acid deposited polyaniline thin-film sensor shows the most outstanding sensitivity and selectivity to H2S and SO2 when concentration of gases range from 10 to 100 μL/L, with sensitivity changing linearly with concentration of gases. The sensor also possesses excellent long-time and thermal stability. This research lays the foundation for preparing practical gas-sensing devices to detect H2S and SO2 in gas-insulated switchgears at room temperature. PMID:27834895

In silico prediction of drug dissolution and absorption with variation in intestinal pH for BCS class II weak acid drugs: ibuprofen and ketoprofen.

PubMed

Tsume, Yasuhiro; Langguth, Peter; Garcia-Arieta, Alfredo; Amidon, Gordon L

2012-10-01

The FDA Biopharmaceutical Classification System guidance allows waivers for in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms only for BCS class I. Extensions of the in vivo biowaiver for a number of drugs in BCS class III and BCS class II have been proposed, in particular, BCS class II weak acids. However, a discrepancy between the in vivo BE results and in vitro dissolution results for BCS class II acids was recently observed. The objectives of this study were to determine the oral absorption of BCS class II weak acids via simulation software and to determine if the in vitro dissolution test with various dissolution media could be sufficient for in vitro bioequivalence studies of ibuprofen and ketoprofen as models of carboxylic acid drugs. The oral absorption of these BCS class II acids from the gastrointestinal tract was predicted by GastroPlus™. Ibuprofen did not satisfy the bioequivalence criteria at lower settings of intestinal pH of 6.0. Further the experimental dissolution of ibuprofen tablets in a low concentration phosphate buffer at pH 6.0 (the average buffer capacity 2.2 mmol l (-1) /pH) was dramatically reduced compared with the dissolution in SIF (the average buffer capacity 12.6 mmol l (-1) /pH). Thus these predictions for the oral absorption of BCS class II acids indicate that the absorption patterns depend largely on the intestinal pH and buffer strength and must be considered carefully for a bioequivalence test. Simulation software may be a very useful tool to aid the selection of dissolution media that may be useful in setting an in vitro bioequivalence dissolution standard. Copyright © 2012 John Wiley & Sons, Ltd.

Absorption and emission behaviour of trans- p-coumaric acid in aqueous solutions and some organic solvents

NASA Astrophysics Data System (ADS)

Putschögl, M.; Zirak, P.; Penzkofer, A.

2008-01-01

The absorption and fluorescence behaviour of trans- p-coumaric acid ( trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form ( p-CAH 2) and the single anionic form ( p-CAH -) at low pH (p Kna ≈ 4.9), and between the single anionic and the double anionic form ( p-CA 2-) at high pH (p Kaa ≈ 9.35). In the organic solvents studied trans- p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans- p-coumaric acid in aqueous solution is ϕF ≈ 1.4 × 10 -4 for the neutral and the single anionic form, while it is ϕF ≈ 1.3 × 10 -3 for the double anionic form. For trans- p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 × 10 -5 (acetonitrile) to 1.5 × 10 -4 (glycerol) were measured. The fluorescence spectra are 7700-10,000 cm -1 Stokes shifted in aqueous solution, and 5400-8200 cm -1 Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA 2-, solvent-assisted intra-molecular charge-transfer or ππ ∗ to nπ ∗ transfer and internal conversion for p-CAH 2 and p-CAH -). The solvent dependence of the first ππ ∗ electronic transition frequency and of the fluorescence Stokes shift of p-CAH 2 is discussed in terms of polar solute-solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted.

Effects of solvent polarity on the absorption and fluorescence spectra of chlorogenic acid and caffeic acid compounds: determination of the dipole moments.

PubMed

Belay, Abebe; Libnedengel, Ermias; Kim, Hyung Kook; Hwang, Yoon-Hwae

2016-02-01

The effects of solvent polarity on absorption and fluorescence spectra of biologically active compounds (chlorogenic acid (CGA) and caffeic acids (CA)) have been investigated. In both spectra pronounced solvatochromic effects were observed with shift of emission peaks larger than the corresponding UV-vis electronic absorption spectra. From solvatochromic theory the ground and excited-state dipole moments were determined experimentally and theoretically. The differences between the excited and ground state dipole moment determined by Bakhshiev, Kawski-Chamma-Viallet and Reichardt equations are quite similar. The ground and excited-state dipole moments were determined by theoretical quantum chemical calculation using density function theory (DFT) method (Gaussian 09) and were also similar to the experimental results. The HOMO-LUMO energy band gaps for CGA and CFA were calculated and found to be 4.1119 and 1.8732 eV respectively. The results also indicated the CGA molecule is more stable than that of CFA. It was also observed that in both compounds the excited state possesses a higher dipole moment than that of the ground state. This confirms that the excited state of the hydroxycinnamic compounds is more polarized than that of the ground state and therefore is more sensitive to the solvent. Copyright © 2015 John Wiley & Sons, Ltd.

In Silico Prediction of Drug Dissolution and Absorption with variation in Intestinal pH for BCS Class II Weak Acid Drugs: Ibuprofen and Ketoprofen§

PubMed Central

Tsume, Yasuhiro; Langguth, Peter; Garcia-Arieta, Alfredo; Amidon, Gordon L.

2012-01-01

The FDA Biopharmaceutical Classification System guidance allows waivers for in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms only for BCS class I. Extensions of the in vivo biowaiver for a number of drugs in BCS Class III and BCS class II have been proposed, particularly, BCS class II weak acids. However, a discrepancy between the in vivo- BE results and in vitro- dissolution results for a BCS class II acids was recently observed. The objectives of this study were to determine the oral absorption of BCS class II weak acids via simulation software and to determine if the in vitro dissolution test with various dissolution media could be sufficient for in vitro bioequivalence studies of ibuprofen and ketoprofen as models of carboxylic acid drugs. The oral absorption of these BCS class II acids from the gastrointestinal tract was predicted by GastroPlus™. Ibuprofen did not satisfy the bioequivalence criteria at lower settings of intestinal pH=6.0. Further the experimental dissolution of ibuprofen tablets in the low concentration phosphate buffer at pH 6.0 (the average buffer capacity 2.2 mmol L-1/pH) was dramatically reduced compared to the dissolution in SIF (the average buffer capacity 12.6 mmol L -1/pH). Thus these predictions for oral absorption of BCS class II acids indicate that the absorption patterns largely depend on the intestinal pH and buffer strength and must be carefully considered for a bioequivalence test. Simulation software may be very useful tool to aid the selection of dissolution media that may be useful in setting an in vitro bioequivalence dissolution standard. PMID:22815122

Piezoelectric-tuned microwave cavity for absorption spectrometry

DOEpatents

Leskovar, Branko; Buscher, Harold T.; Kolbe, William F.

1978-01-01

Gas samples are analyzed for pollutants in a microwave cavity that is provided with two highly polished walls. One wall of the cavity is mechanically driven with a piezoelectric transducer at a low frequency to tune the cavity over a band of microwave frequencies in synchronism with frequency modulated microwave energy applied to the cavity. Absorption of microwave energy over the tuned frequencies is detected, and energy absorption at a particular microwave frequency is an indication of a particular pollutant in the gas sample.

The inhibitory effect of milk on the absorption of dietary phenolic acids and the change in human plasma antioxidant capacity through a mechanism involving both milk proteins and fats.

PubMed

Zhang, Hao; Jiang, Lu; Guo, Huiyuan; Sun, Jing; Liu, Xianting; Liu, Ruihai; Ding, Qingbo; Ren, Fazheng

2013-07-01

We assessed the effects of milk proteins and fats, alone and in combination, on the absorption of phenolic acids and the change in plasma antioxidant capacity after jujube juice intake in humans. Twenty volunteers received the following four treatments each in a 4 × 4 Latin square design with a minimum 1 week interval: 200 mL of jujube juice plus 200 mL of (1) water; (2) whole milk; (3) skimmed milk; or (4) milk fat. The results showed that skimmed milk extended the time to reach maximum increase of plasma phenolic acids concentrations and plasma antioxidant capacity. However, neither the skimmed milk nor the milk fat had a significant effect on the absorption of phenolic acids. In contrast, whole milk significantly reduced the absorption of phenolic acids and the increase in plasma antioxidant capacity (p < 0.05). In vitro results suggested the formation of complexes during digestion that involved milk proteins, milk fats, and phenolic acids, which were responsible for the inhibitory effect of whole milk. Milk proteins and fats together, but not alone, are responsible for the inhibitory effect of milk on the absorption of phenolic acids and the change in plasma antioxidant capacity. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Removal of Sulfur Dioxide from Flue Gas Using the Sludge Sodium Humate

PubMed Central

Hu, Guoxin

2013-01-01

This study shows the ability of sodium humate from alkaline treatment sludge on removing sulfur dioxide (SO2) in the simulated flue gas. Experiments were conducted to examine the effect of various operating parameters, like the inlet SO2 concentration or temperature or O2, on the SO2 absorption efficiency and desulfurization time in a lab-scale bubbling reactor. The sludge sodium humate in the supernatant after alkaline sludge treatment shows great performance in SO2 absorption, and such efficiency can be maintained above 98% with 100 mL of this absorption solution at 298 K (flue gas rate of 0.12 m3/h). The highest SO2 absorption by 1.63 g SHA-Na is 0.946 mmol in the process, which is translated to 0.037 g SO2 g−1 SHA-Na. The experimental results indicate that the inlet SO2 concentration slightly influences the SO2 absorption efficiency and significantly influences the desulfurization time. The pH of the absorption solution should be above 3.5 in this process in order to make an effective desulfurization. The products of this process were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. It can be seen that the desulfurization products mainly contain sludge humic acid sediment, which can be used as fertilizer components. PMID:24453875

Probing Lewis Acid-Base Interactions with Born-Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum of p-Nitroaniline in Supercritical CO2.

PubMed

Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

2015-07-02

The structure and dynamics of p-nitroaniline (PNA) in supercritical CO2 (scCO2) at T = 315 K and ρ = 0.81 g cm(-3) are investigated by carrying out Born-Oppenheimer molecular dynamics, and the electronic absorption spectrum in scCO2 is determined by time dependent density functional theory. The structure of the PNA-scCO2 solution illustrates the role played by Lewis acid-base (LA-LB) interactions. In comparison with isolated PNA, the ν(N-O) symmetric and asymmetric stretching modes of PNA in scCO2 are red-shifted by -17 and -29 cm(-1), respectively. The maximum of the charge transfer (CT) absorption band of PNA in scSCO2 is at 3.9 eV, and the predicted red-shift of the π → π* electronic transition relative to the isolated gas-phase PNA molecule reproduces the experimental value of -0.35 eV. An analysis of the relationship between geometry distortions and excitation energies of PNA in scCO2 shows that the π → π* CT transition is very sensitive to changes of the N-O bond distance, strongly indicating a correlation between vibrational and electronic solvatochromism driven by LA-LB interactions. Despite the importance of LA-LB interactions to explain the solvation of PNA in scCO2, the red-shift of the CT band is mainly determined by electrostatic interactions.

Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Lijing; Xu Xiangyu; Evans, David G.

2010-05-15

An MgAl-NO{sub 3}-layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filledmore » with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO{sub 3}-LDH in the 7-25 {mu}m range, particularly in the key 9-11 {mu}m range required for application in agricultural plastic films. - Graphical abstract: Intercalation of iminodiacetic acid (IDA) anions in a MgAl-NO{sub 3}-layered double hydroxide host leads to an enhancement of its infrared absorbing ability for application in agricultural plastic films.« less

Vacuum ultraviolet detector for gas chromatography.

PubMed

Schug, Kevin A; Sawicki, Ian; Carlton, Doug D; Fan, Hui; McNair, Harold M; Nimmo, John P; Kroll, Peter; Smuts, Jonathan; Walsh, Phillip; Harrison, Dale

2014-08-19

Analytical performance characteristics of a new vacuum ultraviolet (VUV) detector for gas chromatography (GC) are reported. GC-VUV was applied to hydrocarbons, fixed gases, polyaromatic hydrocarbons, fatty acids, pesticides, drugs, and estrogens. Applications were chosen to feature the sensitivity and universal detection capabilities of the VUV detector, especially for cases where mass spectrometry performance has been limited. Virtually all chemical species absorb and have unique gas phase absorption cross sections in the approximately 120-240 nm wavelength range monitored. Spectra are presented, along with the ability to use software for deconvolution of overlapping signals. Some comparisons with experimental synchrotron data and computed theoretical spectra show good agreement, although more work is needed on appropriate computational methods to match the simultaneous broadband electronic and vibronic excitation initiated by the deuterium lamp. Quantitative analysis is governed by Beer-Lambert Law relationships. Mass on-column detection limits reported for representatives of different classes of analytes ranged from 15 (benzene) to 246 pg (water). Linear range measured at peak absorption for benzene was 3-4 orders of magnitude. Importantly, where absorption cross sections are known for analytes, the VUV detector is capable of absolute determination (without calibration) of the number of molecules present in the flow cell in the absence of chemical interferences. This study sets the stage for application of GC-VUV technology across a wide breadth of research areas.

Method for mapping a natural gas leak

DOEpatents

Reichardt, Thomas A [Livermore, CA; Luong, Amy Khai [Dublin, CA; Kulp, Thomas J [Livermore, CA; Devdas, Sanjay [Albany, CA

2009-02-03

A system is described that is suitable for use in determining the location of leaks of gases having a background concentration. The system is a point-wise backscatter absorption gas measurement system that measures absorption and distance to each point of an image. The absorption measurement provides an indication of the total amount of a gas of interest, and the distance provides an estimate of the background concentration of gas. The distance is measured from the time-of-flight of laser pulse that is generated along with the absorption measurement light. The measurements are formatted into an image of the presence of gas in excess of the background. Alternatively, an image of the scene is superimposed on the image of the gas to aid in locating leaks. By further modeling excess gas as a plume having a known concentration profile, the present system provides an estimate of the maximum concentration of the gas of interest.

Inhibitory effect and mechanism of acarbose combined with gymnemic acid on maltose absorption in rat intestine

PubMed Central

Luo, Hong; Wang, Le Feng; Imoto, Toshiaki; Hiji, Yasutake

2001-01-01

AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1 g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P < 0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3 h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1 g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA, which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination. PMID:11819725

Thermal decarboxylation of acetic acid: Implications for origin of natural gas

USGS Publications Warehouse

Kharaka, Y.K.; Carothers, W.W.; Rosenbauer, R.J.

1983-01-01

Laboratory experiments on the thermal decarboxylation of solutions of acetic acid at 200??C and 300??C were carried out in hydrothermal equipment allowing for on-line sampling of both the gas and liquid phases for chemical and stable-carbon-isotope analyses. The solutions had ambient pH values between 2.5 and 7.1; pH values and the concentrations of the various acetate species at the conditions of the experiments were computed using a chemical model. Results show that the concentrations of acetic acid, and not total acetate in solution, control the reaction rates which follow a first order equation based on decreasing concentrations of acetic acid with time. The decarboxylation rates at 200??C (1.81 ?? 10-8 per second) and 300??C (8.17 ?? 10-8 per second) and the extrapolated rates at lower temperatures are relatively high. The activation energy of decarboxylation is only 8.1 kcal/mole. These high decarboxylation rates, together with the distribution of short-chained aliphatic acid anions in formation waters, support the hypothesis that acid anions are precursors for an important portion of natural gas. Results of the ??13C values of CO2, CH4, and total acetate show a reasonably constant fractionation factor of about 20 permil between CO2 and CH4 at 300??C. The ??13C values of CO2 and CH4 are initially low and become higher as decarboxylation increases. ?? 1983.

Infrared laser spectroscopic trace gas sensing

NASA Astrophysics Data System (ADS)

Sigrist, Markus

2016-04-01

-lived species like nitrous acid (HONO) with a QCL-based QEPAS system where the small gas sampling volume and hence short gas residence time are of particular importance [3]. A true analysis of gas mixtures has been performed with a widely tunable DFG system in a medical application that could also be adapted to atmospheric species [4]. It is demonstrated that a laser-based narrowband system with broad tunability combined with an appropriate detection scheme is feasible for the chemical analysis of multi-component gas mixtures even with an a priori unknown composition. Most recent examples will further confirm the great potential of infrared laser-based devices for trace species sensing. References 1. D. Marinov and M.W. Sigrist: "Monitoring of road-traffic emission with mobile photoacoustic system", Photochem. and Photobiol. Sciences 2, 774-778 (2003) 2. J.M. Rey, M. Fill, F. Felder and M.W. Sigrist: "Broadly tunable mid-infrared VECSEL for multiple components hydrocarbons gas sensing", Appl. Phys. B 117, 935-939 (2014) 3. H. Yi, R. Maamary, X. Gao, M.W. Sigrist, E. Fertein, and W. Chen: "Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy", Appl. Phys. Lett. 106, 101109 (2015) 4. M. Gianella and M.W. Sigrist: "Chemical Analysis of Surgical Smoke by Infrared Laser Spectroscopy", Appl. Phys. B 109, 485-496 (2012)

Method for the routine quantitative gas chromatographic analysis of major free fatty acids in butter and cream.

PubMed

Woo, A H; Lindsay, R C

1980-07-01

A rapid quantiative method was developed for routine analysis of the major, even carbon-numbered free fatty acids in butter and cream. Free fatty acids were isolated directly from intact samples by a modified silicic acid-potassium hydroxide arrestant column and were separated by gas chromatography with a 1.8 m x 2 mm inner diameter glass column packed with 10% neopentyl glycol adipate on 80/100 Chromosorb W. Purified, formic acid-saturated carrier gas was required for minimal peak tailing and extended column life. The accuracy and reproducibility of the mmethod was established through quantitative recovery studies of free fatty acid mixtures, free fatty acids added to butter, and replicate analysis of butter and cream samples.

Absorption and emission spectra of Li atoms trapped in rare gas matrices

NASA Astrophysics Data System (ADS)

Wright, J. J.; Balling, L. C.

1980-10-01

Pulsed-dye-laser excitation has been used to investigate the optical absorption and emission spectra of Li atoms trapped in Ar, Kr, and Xe matrices at 10 °K. Attempts to stabilize Li atoms in a Ne matrix at 2 °K were unsuccessful. Results for all three rare gases were qualitatively the same. White light absorption scans showed a single absorption with three peaks centered near the free-atom 2s→2p transition wavelength. The intensity of fluorescence produced by dye-laser excitation within this absorption band was measured as a function of emission wavelength. Excitation of the longest- and shortest-wavelength absorption peaks produced identical emission profiles, but no distinct fluorescence signal was detected when the laser was tuned to the central absorption peaks, indicating that the apparent absorption triplet is actually the superposition of a singlet and a doublet absorption originating from two different trapping sites. No additional absorption bands were detected.

Effect of ionization and vehicle on skin absorption and penetration of azelaic acid.

PubMed

Li, Nan; Wu, Xiaohong; Jia, Weibu; Zhang, Michelle C; Tan, Fengping; Zhang, Jerry

2012-08-01

The aim of this study is to investigate the effect of ionization and vehicle of topical formulations on skin absorption and penetration of azelaic acid (AZA). In vitro transport of AZA was determined for two topical formulations containing AZA with pH values of 3.9 and 4.9, respectively. FINACEA(®) (15% AZA gel), a US Food and Drug Administration approved drug for treatment of acne and rosacea, was also used for comparison. Release profile and flux of AZA were determined in an in vitro hairless mouse skin model using Franz Diffusion Cell. The data have shown that a higher concentration of AZA is retained in the epidermis/dermis layer and the whole skin for the formulation with pH = 4.9 as compared to that with pH = 3.9 at an active loading level of 2.82 mg/cm(2). In addition, the flux of ionized species of AZA in the pH 4.9 formulation (128.4 ± 35.9 μg/cm(2)/h) is approximately five-fold greater than that in the pH 3.9 formulation (27.7 ± 4.0 μg/cm(2)/h). The results suggest that the ionized AZA penetrates through the skin and accounts for majority of the total flux. This study has demonstrated that the penetration and absorption of AZA show a strong pH- and vehicle-dependency. Solubilization is the rate-limiting step in percutaneous absorption of AZA.

Effects of emulsified octadecanic acids on gas production and cellulolysis by the rumen anaerobic fungus, Piromyces communis M014.

PubMed

Kim, Chang-H; Lee, Shin J; Ha, Jong K; Kim, Wan Y; Lee, Sung S

2008-02-01

Responses of the rumen anaerobic fungus, Piromyces communis M014, to octadecanic long-chain fatty acids (LCFAs) were evaluated by measuring total and hydrogen gas productions, filter paper (FP) cellulose degradation and polysaccharidase enzyme activities. Octadecanic acids (stearic acid, C(18:0); oleic acid, C(18:1); linoleic acid, C(18:2) and linolenic acid, C(18:3)) were emulsified by ultrasonication under anaerobic conditions, and added to the medium at the level of 0.001%. When P. communis M014 was grown in culture with stearic and oleic acids, the cumulative gas production, FP cellulose digestion and enzyme activities were significantly (p<0.05) increased in the early incubation times relative to those for the control. However, the addition of linolenic acid inhibited all of the investigated parameters, including cellulose degradation, enzyme activities and gas production, up to 168h incubation. These results indicated that stearic and oleic acids tended to have stimulatory effects on fungal cellulolysis, whereas linolenic acid caused a significant (p<0.05) inhibitory effect on cellulolysis by the rumen fungus. The fungus, P. communis M014, can biohydrogenate C(18) unsaturated fatty acids to escape from their toxic effects. Therefore, in this study, the results indicated that the more highly the added C(18) LCFA to the fungal culture was unsaturated, the higher the inhibition of gas production and cellulase enzyme activity was.

Nitrogen dioxide absorption in aqueous sodium sulfite

NASA Astrophysics Data System (ADS)

Shen, Chen Hua

The Clean Air Act of 1990 requires additional reduction of acid gases, sulfur dioxide, and nitrogen oxides released into the atmosphere from coal-fired electric power plants. In the case of older existing power plants, a possible retrofit strategy is to oxidize nitric oxide (NO, the major constituent of NOsbX in flue gas) to nitrogen dioxide (NOsb2) by the addition of methanol or other hydrocarbons into the duct at an optimum temperature regime. NOsb2 can then be removed by either modifying existing SOsb2 control equipment or by adding a limestone (CaCOsb3) slurry scrubbing process. Limestone reacts with SOsb2 to from CaSOsb3, and the free sulfite (SO{sb3sp{=}}) in the solution is reactive toward NOsb2. The focus of this research is to study the reaction between NOsb2 and aqueous sulfite at elevated temperature and in the presence of gas phase Osb2. The removal of NOsb2 by limestone slurry scrubbing involves the reaction between NOsb2 and SO{sb3sp{=}}, bisulfite (HSO{sb3sp{-}}) and water. The reactions between NOsb2 and SO{sb3sp{=}}/HSO{sb3sp{-}} are first order in both reactants, while the NOsb2-water reaction is second order in NOsb2 concentration. The rate constants of the above reactions and the NOsb2-thiosulfate (Ssb2O{sb3sp{=}}) reaction were determined at 55sp°C. SO{sb3sp{=}} was found to be the most reactive toward NOsb2, while the contribution of chemical reaction still dominated in the absorption of NOsb2 into water. The effect of gas phase SOsb2 and Osb2, and liquid phase additives such as Ssb2O{sb3sp{=}}, Casp{++}, Mgsp{++}, and Clsp{-} on NOsb2 absorption was also investigated. The absorption of NOsb2 catalyzes free radical reactions that lead to sulfite oxidation. A semi-empirical model was proposed to relate the rate of sulfite oxidation to the rate of NOsb2 absorption. Thiosulfate inhibits sulfite oxidation by providing an alternative route for the termination of the free radical reactions, and a fundamental model was derived to quantify the effect

ALMA observations of molecular absorption in four directions toward the Galactic bulge

NASA Astrophysics Data System (ADS)

Liszt, H.; Gerin, M.

2018-02-01

Context. Alma Cycle 3 observations serendipitously showed strong absorption from diffuse molecular gas in the Galactic bulge at -200 km s-1 < v < -140 km s-1 toward the compact extragalactic continuum source J1744-3116 at (l, b) = -2.13∘, - 1.00∘. Aims: We aimed to test whether molecular gas in the bulge could also be detected toward the three other, sufficiently strong mm-wave continuum sources seen toward the bulge at |b| < 3∘. Methods: We took absorption profiles of HCO+ (1-0), HCN(1-0), C2H(1-0), CS(2-1) and H13CO+(1-0) in ALMA Cycle 4 toward J1713-3418, J1717-3341, J1733-3722 and J1744-3116. Results: Strong molecular absorption from disk gas at |ν| ≲ 30 km s-1 was detected in all directions, and absorption from the 3 kpc arm was newly detected toward J1717 and J1744. However, only the sightline toward J1744 is dominated by molecular gas overall and no other sightlines showed molecular absorption from gas deep inside the bulge. No molecular absorption was detected toward J1717 where H I emission from the bulge was previously known. As observed in HCO+, HCN, C2H and CS, the bulge gas toward J1744 at v < -135 km s-1 has chemistry and kinematics like that seen near the Sun and in the Milky Way disk generally. We measured isotopologic ratios N(HCO+)/N(H13CO+) > 51(3σ) for the bulge gas toward J1744 and 58 ± 9 and 64 ± 4 for the disk gas toward J1717 and J1744, respectively, all well above the value of 20-25 typical of the central molecular zone. Conclusions: The kinematics and chemistry of the bulge gas observed toward J1744 more nearly resemble that of gas in the Milky Way disk than in the central molecular zone.

Fast spatially resolved exhaust gas recirculation (EGR) distribution measurements in an internal combustion engine using absorption spectroscopy.

PubMed

Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

2015-09-01

Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. The study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.

Fast Spatially Resolved Exhaust Gas Recirculation (EGR) Distribution Measurements in an Internal Combustion Engine Using Absorption Spectroscopy

DOE PAGES

Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E.; ...

2015-09-01

One effective method of reducing NO x emissions while improving efficiency is exhaust gas recirculation (EGR) in internal combustion engines. But, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder nonuniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. Furthermore, a sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO 2 concentration at various locationsmore » in the intake manifold. Our study employed mid-infrared light sources tuned to an absorption band of CO 2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.« less

Toxic Acid Gas Absorber Design Considerations for Air Pollution Control in Process Industries

ERIC Educational Resources Information Center

Manyele, S. V.

2008-01-01

This paper analyses the design parameters for an absorber used for removal of toxic acid gas (in particular sulfur dioxide) from a process gas stream for environmental health protection purposes. Starting from the equilibrium data, Henry's law constant was determined from the slope of the y-x diagram. Based on mass balances across the absorber,…

Oxalic acid does not influence nonhaem iron absorption in humans: a comparison of kale and spinach meals.

PubMed

genannt Bonsmann, S Storcksdieck; Walczyk, T; Renggli, S; Hurrell, R F

2008-03-01

To evaluate the influence of oxalic acid (OA) on nonhaem iron absorption in humans. Two randomized crossover stable iron isotope absorption studies. Zurich, Switzerland. Sixteen apparently healthy women (18-45 years, <60 kg body weight), recruited by poster advertizing from the staff and student populations of the ETH, University and University Hospital of Zurich, Switzerland. Thirteen subjects completed both studies. Iron absorption was measured based on erythrocyte incorporation of (57)Fe or (58)Fe 14 days after the administration of labelled meals. In study I, test meals consisted of two wheat bread rolls (100 g) and either 150 g spinach with a native OA content of 1.27 g (reference meal) or 150 g kale with a native OA content of 0.01 g. In study II, 150 g kale given with a potassium oxalate drink to obtain a total OA content of 1.27 g was compared to the spinach meal. After normalization for the spinach reference meal absorption, geometric mean iron absorption from wheat bread rolls with kale (10.7%) did not differ significantly from wheat rolls with kale plus 1.26 g OA added as potassium oxalate (11.5%, P=0.86). Spinach was significantly higher in calcium and polyphenols than kale and absorption from the spinach meal was 24% lower compared to the kale meal without added OA, but the difference did not reach statistical significance (P>0.16). Potassium oxalate did not influence iron absorption in humans from a kale meal and our findings strongly suggest that OA in fruits and vegetables is of minor relevance in iron nutrition.

Real-time trace gas sensor using a multimode diode laser and multiple-line integrated cavity enhanced absorption spectroscopy.

PubMed

Karpf, Andreas; Rao, Gottipaty N

2015-07-01

We describe and demonstrate a highly sensitive trace gas sensor based on a simplified design that is capable of measuring sub-ppb concentrations of NO2 in tens of milliseconds. The sensor makes use of a relatively inexpensive Fabry-Perot diode laser to conduct off-axis cavity enhanced spectroscopy. The broad frequency range of a multimode Fabry-Perot diode laser spans a large number of absorption lines, thereby removing the need for a single-frequency tunable laser source. The use of cavity enhanced absorption spectroscopy enhances the sensitivity of the sensor by providing a pathlength on the order of 1 km in a small volume. Off-axis alignment excites a large number of cavity modes simultaneously, thereby reducing the sensor's susceptibility to vibration. Multiple-line integrated absorption spectroscopy (where one integrates the absorption spectra over a large number of rovibronic transitions of the molecular species) further improves the sensitivity of detection. Relatively high laser power (∼400  mW) is used to compensate for the low coupling efficiency of a broad linewidth laser to the optical cavity. The approach was demonstrated using a 407 nm diode laser to detect trace quantities of NO2 in zero air. Sensitivities of 750 ppt, 110 ppt, and 65 ppt were achieved using integration times of 50 ms, 5 s, and 20 s respectively.

Slow light enhanced gas sensing in photonic crystals

NASA Astrophysics Data System (ADS)

Kraeh, Christian; Martinez-Hurtado, J. L.; Popescu, Alexandru; Hedler, Harry; Finley, Jonathan J.

2018-02-01

Infrared spectroscopy allows for highly selective and highly sensitive detection of gas species and concentrations. Conventional gas spectrometers are generally large and unsuitable for on-chip applications. Long absorption path lengths are usually required and impose a challenge for miniaturization. In this work, a gas spectrometer is developed consisting of a microtube photonic crystal structure. This structure of millimetric form factors minimizes the required absorption path length due to slow light effects. The microtube photonic crystal allows for strong transmission in the mid-infrared and, due to its large void space fraction, a strong interaction between light and gas molecules. As a result, enhanced absorption of light increases the gas sensitivity of the device. Slow light enhanced gas absorption by a factor of 5.8 in is experimentally demonstrated at 5400 nm. We anticipate small form factor gas sensors on silicon to be a starting point for on-chip gas sensing architectures.

Speciation of sulfur in humic and fulvic acids using X-ray absorption near-edge structure (XANES) spectroscopy

NASA Astrophysics Data System (ADS)

Morra, Matthew J.; Fendorf, Scott E.; Brown, Paul D.

1997-02-01

Sulfur species in soils and sediments have previously been determined indirectly using destructive techniques. A direct and more accurate method for S speciation would improve our understanding of S biogeochemistry. X-ray absorption near edge structure (XANES) spectroscopy was performed on purified humic and fulvic acids from terrestrial and aquatic environments. This methodology allows direct determination of S species using the relationship that exists with the energy required for core electron transitions and in some cases, correlation with additional spectral features. Soil, peat, and aquatic humic acids were dominated by sulfonates with an oxidation state of +5, but also contained ester-bonded sulfates with an oxidation state of +6. Leonardite humic acid contained ester-bonded sulfate and an unidentified S compound with an oxidation state of +4.0. In contrast, high-valent S in soil, peat, and aquatic fulvic acids was exclusively in the form of sulfonic acids. Reduced S species were also present in both humic and fulvic acids. XANES is a valuable method for the speciation of S in humic materials and of potential use in S speciation of unfractionated soils.

Gas Phase Absorption Spectroscopy of C+60 and C+70 in a Cryogenic Ion Trap: Comparison with Astronomical Measurements

NASA Astrophysics Data System (ADS)

Campbell, E. K.; Holz, M.; Maier, J. P.; Gerlich, D.; Walker, G. A. H.; Bohlender, D.

2016-05-01

Recent low-temperature laboratory measurements and astronomical observations have proved that the fullerene cation {{{C}}}60+ is responsible for four diffuse interstellar bands (DIBs). These absorptions correspond to the strongest bands of the lowest electronic transition. The gas phase spectrum below 10 {{K}} is reported here for the full wavelength range encompassed by the electronic transition. The absorption spectrum of {{{C}}}70+, with its origin band at 7959.2 {{\\mathringA }}, has been obtained under similar laboratory conditions. Observations made toward the reddened star {HD} 183143 were used in a specific search for the absorption of these fullerene cations in diffuse clouds. In the case of {{{C}}}60+, one further band in the astronomical spectrum at 9348.5 \\mathringA is identified, increasing the total number of assigned DIBs to five. Numerous other {{{C}}}60+ absorptions in the laboratory spectrum are found to lie below the astronomical detection limit. Special emphasis is placed on the laboratory determination of absolute absorption cross-sections. For {{{C}}}60+ this directly yields a column density, N({{{C}}}60+), of 2× {10}13 {{{cm}}}-2 in diffuse clouds, without the need to rely on theoretical oscillator strengths. The intensity of the {{{C}}}70+ electronic transition in the range 7000-8000 Å is spread over many features of similar strength. Absorption cross-section measurements indicate that even for a similar column density, the individual absorption bands of {{{C}}}70+ will be too weak to be detected in the astronomical spectra, which is confirmed giving an upper limit of 2 {{m\\mathringA }} to the equivalent width. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

Evidence of In Vivo Absorption of Lactate and Modulation of Short Chain Fatty Acid Absorption from the Reticulorumen of Non-Lactating Cattle Fed High Concentrate Diets.

PubMed

Qumar, Muhammad; Khiaosa-Ard, Ratchaneewan; Pourazad, Poulad; Wetzels, Stefanie U; Klevenhusen, Fenja; Kandler, Wolfgang; Aschenbach, Jörg R; Zebeli, Qendrim

2016-01-01

Short-chain fatty acids (SCFAs) and lactate are endproducts of rumen fermentation and important energy sources for the host ruminant. Because their rapid accumulation results in ruminal acidosis, enhancement of the absorption of SCFA and lactate across reticuloruminal wall is instrumental in increasing energy supply and preventing ruminal acidosis in cattle. This study investigated whether the reticuloruminal absorption of SCFAs and lactate was altered by different strategies of high concentrate feeding. Eight rumen-cannulated, non-lactating Holstein cows were fed a forage-only diet (baseline) and then gradually adapted over 6 d to a 60% concentrate level. Thereafter, this concentrate-rich diet was fed for 4 wk either continuously (Con; n = 8) or interruptedly (Int; n = 8). Absorption of SCFAs and lactate was determined in vivo from the experimental buffer introduced into the washed reticulorumen. The buffer contained acetate, propionate, butyrate and lactate at a concentration of 60, 30, 10 and 5 mmol/L, respectively and Cr-EDTA as a marker for correcting ruminal water fluxes. The reticuloruminal absorption after 35 and 65 min of buffer incubation was measured at the baseline, after 1 wk of 60% concentrate feeding in the interrupted model (Int-1) and after 4 wk of concentrate feeding in both feeding models (Int-4 and Con-4). Data showed that the absorption rates of individual and total SCFAs during the first 35 min of incubation of Con-4 were highest (~1.7 times compared to baseline), while Int-1 and Int-4 were similar to respective baseline. Lactate was not absorbed during forage-only baseline and 1-wk concentrate feeding, but after 4-wk feeding of concentrates in both models. In conclusion, SCFAs absorption across the reticulorumen of non-lactating cattle was enhanced by the 4-wk continuous concentrate feeding, which seems to be more advantageous in terms of rumen acidosis prevention compared to the interrupted feeding model. The study provides evidence of

Evidence of In Vivo Absorption of Lactate and Modulation of Short Chain Fatty Acid Absorption from the Reticulorumen of Non-Lactating Cattle Fed High Concentrate Diets

PubMed Central

Qumar, Muhammad; Khiaosa-ard, Ratchaneewan; Pourazad, Poulad; Wetzels, Stefanie U.; Klevenhusen, Fenja; Kandler, Wolfgang; Aschenbach, Jörg R.; Zebeli, Qendrim

2016-01-01

Short-chain fatty acids (SCFAs) and lactate are endproducts of rumen fermentation and important energy sources for the host ruminant. Because their rapid accumulation results in ruminal acidosis, enhancement of the absorption of SCFA and lactate across reticuloruminal wall is instrumental in increasing energy supply and preventing ruminal acidosis in cattle. This study investigated whether the reticuloruminal absorption of SCFAs and lactate was altered by different strategies of high concentrate feeding. Eight rumen-cannulated, non-lactating Holstein cows were fed a forage-only diet (baseline) and then gradually adapted over 6 d to a 60% concentrate level. Thereafter, this concentrate-rich diet was fed for 4 wk either continuously (Con; n = 8) or interruptedly (Int; n = 8). Absorption of SCFAs and lactate was determined in vivo from the experimental buffer introduced into the washed reticulorumen. The buffer contained acetate, propionate, butyrate and lactate at a concentration of 60, 30, 10 and 5 mmol/L, respectively and Cr-EDTA as a marker for correcting ruminal water fluxes. The reticuloruminal absorption after 35 and 65 min of buffer incubation was measured at the baseline, after 1 wk of 60% concentrate feeding in the interrupted model (Int-1) and after 4 wk of concentrate feeding in both feeding models (Int-4 and Con-4). Data showed that the absorption rates of individual and total SCFAs during the first 35 min of incubation of Con-4 were highest (~1.7 times compared to baseline), while Int-1 and Int-4 were similar to respective baseline. Lactate was not absorbed during forage-only baseline and 1-wk concentrate feeding, but after 4-wk feeding of concentrates in both models. In conclusion, SCFAs absorption across the reticulorumen of non-lactating cattle was enhanced by the 4-wk continuous concentrate feeding, which seems to be more advantageous in terms of rumen acidosis prevention compared to the interrupted feeding model. The study provides evidence of

Gas chromatographic determination of carboxylic acid chlorides and residual carboxylic acid precursors used in the production of some penicillins.

PubMed

Lauback, R G; Balitz, D F; Mays, D L

1976-05-01

An improved gas chromatographic method is described for the simultaneous determination of carboxylic acid chlorides and related carboxylic acids used in the production of some commercial semisynthetic penicillins. The acid chloride reacts with diethylamine to form the corresponding diethylamide. Carboxylic acid impurities are converted to trimethylsilyl esters. The two derivatives are separated and quantitated in the same chromatographic run. This method, an extension of the earlier procedure of Hishta and Bomstein (1), has been applied to the acid chlorides used to make oxacillin, cloxacillin, dicloxacillin, and methicillin (Figure 1); it shows promise of application to other acid chlorides. The determination is more selective than the usual titration methods, which do not differentiate among acids with similar pK's. Relative standard deviations of the acid chloride determination are 1.0-2.5%. Residual carboxylic acid can be repetitively determined within a range of 0.6% absolute.

Fiber optic gas sensor

NASA Technical Reports Server (NTRS)

Chen, Peng (Inventor); Buric, Michael P. (Inventor); Swinehart, Philip R. (Inventor); Maklad, Mokhtar S. (Inventor)

2010-01-01

A gas sensor includes an in-fiber resonant wavelength device provided in a fiber core at a first location. The fiber propagates a sensing light and a power light. A layer of a material is attached to the fiber at the first location. The material is able to absorb the gas at a temperature dependent gas absorption rate. The power light is used to heat the material and increases the gas absorption rate, thereby increasing sensor performance, especially at low temperatures. Further, a method is described of flash heating the gas sensor to absorb more of the gas, allowing the sensor to cool, thereby locking in the gas content of the sensor material, and taking the difference between the starting and ending resonant wavelengths as an indication of the concentration of the gas in the ambient atmosphere.

A Study of the Skin Absorption of Ethylbenzene in Man

PubMed Central

Dutkiewicz, Tadeusz; Tyras, Halina

1967-01-01

The absorption of ethylbenzene through the skin of the hand and the forearm in men was investigated experimentally. Both the absorption of liquid ethylbenzene and the absorption from aqueous solutions were studied. The rate of absorption of liquid ethylbenzene was 22 to 33 mg./cm.2/hr, and the rates from aqueous solutions were 118 and 215 μg./cm.2/hr from mean concentrations of 112 and 156 mg./litre. The mandelic acid excreted in urine was equivalent to about 4·6% of the absorbed dose—much less than after lung absorption. Urinary mandelic acid does not provide a reliable index of absorption when there is simultaneous skin and lung exposure. PMID:6073092

40 CFR 60.5408 - What is an optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure?

Code of Federal Regulations, 2013 CFR

2013-07-01

... measuring hydrogen sulfide in acid gas-Tutwiler Procedure? 60.5408 Section 60.5408 Protection of Environment... § 60.5408 What is an optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure... of titrating hydrogen sulfide in a gas sample directly with a standard solution of iodine. (b...

40 CFR 60.5408 - What is an optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure?

Code of Federal Regulations, 2014 CFR

2014-07-01

... measuring hydrogen sulfide in acid gas-Tutwiler Procedure? 60.5408 Section 60.5408 Protection of Environment... § 60.5408 What is an optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure... of titrating hydrogen sulfide in a gas sample directly with a standard solution of iodine. (b...

Random-hole optical fiber evanescent-wave gas sensing.

PubMed

Pickrell, G; Peng, W; Wang, A

2004-07-01

Research on development of optical gas sensors based on evanescent-wave absorption in random-hole optical fibers is described. A process to produce random-hole optical fibers was recently developed that uses a novel in situ bubble formation technique. Gas molecules that exhibit characteristic vibrational absorption lines in the near-IR region that correspond to the transmission window for silica optical fiber have been detected through the evanescent field of the guided mode in the pore region. The presence of the gas molecules in the holes of the fiber appears as a loss at wavelengths that are characteristic of the particular gas species present in the holes. An experimental setup was constructed with these holey fibers for detection of acetylene gas. The results clearly demonstrate the characteristic absorptions in the optical spectra that correspond to the narrow-line absorptions of the acetylene gas, and this represents what is to our knowledge the first report of random-hole fiber gas sensing in the literature.

Ammonia Gas Sensing Behavior of Tanninsulfonic Acid Doped Polyaniline-TiO2 Composite

PubMed Central

Bairi, Venu Gopal; Bourdo, Shawn E.; Sacre, Nicolas; Nair, Dev; Berry, Brian C.; Biris, Alexandru S.; Viswanathan, Tito

2015-01-01

A highly active tannin doped polyaniline-TiO2 composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI)-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO2 in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO2. Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM) surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO2 and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm) of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO2 composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported. PMID:26501291

Predicting phenolic acid absorption in Caco-2 cells: a theoretical permeability model and mechanistic study.

PubMed

Farrell, Tracy L; Poquet, Laure; Dew, Tristan P; Barber, Stuart; Williamson, Gary

2012-02-01

There is a considerable need to rationalize the membrane permeability and mechanism of transport for potential nutraceuticals. The aim of this investigation was to develop a theoretical permeability equation, based on a reported descriptive absorption model, enabling calculation of the transcellular component of absorption across Caco-2 monolayers. Published data for Caco-2 permeability of 30 drugs transported by the transcellular route were correlated with the descriptors 1-octanol/water distribution coefficient (log D, pH 7.4) and size, based on molecular mass. Nonlinear regression analysis was used to derive a set of model parameters a', β', and b' with an integrated molecular mass function. The new theoretical transcellular permeability (TTP) model obtained a good fit of the published data (R² = 0.93) and predicted reasonably well (R² = 0.86) the experimental apparent permeability coefficient (P(app)) for nine non-training set compounds reportedly transported by the transcellular route. For the first time, the TTP model was used to predict the absorption characteristics of six phenolic acids, and this original investigation was supported by in vitro Caco-2 cell mechanistic studies, which suggested that deviation of the P(app) value from the predicted transcellular permeability (P(app)(trans)) may be attributed to involvement of active uptake, efflux transporters, or paracellular flux.

Application of FIGAERO (Filter Inlet for Gases and AEROsol) coupled to a high resolution time of flight chemical ionization mass spectrometer to field and chamber organic aerosol: Implications for carboxylic acid formation and gas-particle partitioning from monoterpene oxidation

NASA Astrophysics Data System (ADS)

Lopez-Hilfiker, F.; Mohr, C.; Ehn, M.; Rubach, F.; Mentel, T. F.; Kleist, E.; Wildt, J.; Thornton, J. A.

2013-12-01

We present measurements of a large suite of gas and particle phase carboxylic acid containing compounds made with a Filter Inlet for Gas and AEROsol (FIGAERO) coupled to a high resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. A prototype operated with acetate negative ion proton transfer chemistry was deployed on the Julich Plant Atmosphere Chamber to study a-pinene oxidation, and a modified version was deployed at the SMEAR II forest station in Hyytiälä, Finland and SOAS, in Brent Alabama. We focus here on results from JPAC and Hyytiälä, where we utilized the same ionization method most selective towards carboxylic acids. In all locations, 100's of organic acid compounds were observed in the gas and particles and many of the same composition acids detected in the gas-phase were detected in the particles upon temperature programmed thermal desorption. Particulate organics detected by FIGAERO are highly correlated with organic aerosol mass measured by an AMS, providing additional volatility and molecular level information about collected aerosol. The fraction of a given compound measured in the particle phase follows expected trends with elemental composition, but many compounds would not be well described by an absorptive partitioning model assuming unity activity coefficients. Moreover the detailed structure in the thermal desorption signals reveals a contribution from thermal decomposition of large molecular weight organics and or oligomers with implications for partitioning measurements and model validation

Systematic review: Helicobacter pylori infection and impaired drug absorption.

PubMed

Lahner, E; Annibale, B; Delle Fave, G

2009-02-15

Impaired acid secretion may affect drug absorption and may be consequent to corporal Helicobacter pylori-gastritis, which may affect the absorption of orally administered drugs. To focus on the evidence of impaired drug absorption associated with H. pylori infection. Data sources were the systematic search of MEDLINE/EMBASE/SCOPUS databases (1980-April 2008) for English articles using the keywords: drug malabsorption/absorption, stomach, Helicobacter pylori, gastritis, gastric acid, gastric pH, hypochlorhydria, gastric hypoacidity. Study selection was made from 2099 retrieved articles, five studies were identified. Data were extracted from selected papers, investigated drugs, study type, main features of subjects, study design, intervention type and results were extracted. In all, five studies investigated impaired absorption of l-dopa, thyroxine and delavirdine in H. pylori infection. Eradication treatment led to 21-54% increase in l-dopa in Parkinson's disease. Thyroxine requirement was higher in hypochlorhydric goitre with H. pylori-gastritis and thyrotropin levels decreased by 94% after treatment. In H. pylori- and HIV-positive hypochlorhydric subjects, delavirdine absorption increased by 57% with orange juice administration and by 150% after eradication. A plausible mechanism of impaired drug absorption is decreased acid secretion in H. pylori-gastritis patients. Helicobacter pylori infection and hypochlorhydria should be considered in prescribing drugs the absorption of which is potentially affected by intragastric pH.

Simultaneous high efficiency capture of CO.sub.2 and H.sub.2S from pressurized gas

DOEpatents

Gal, Eli; Krishnan, Gopala N.; Jayaweera, Indira S.

2016-10-11

Low-cost and energy-efficient CO.sub.2 and H.sub.2S capture is provided obtaining greater than 99.9% capture efficiency from pressurized gas. The acid species are captured in an ammonia solution, which is then regenerated by stripping the absorbed species. The solution can capture as much as 330 grams of CO.sub.2 and H.sub.2S per 1000 gram of water and when regenerated it produces pure pressurized acid gas containing more than 99.7% CO.sub.2 and H2S. The absorption of the acid species is accomplished in two absorbers in-series, each having multiple stages. More than 95% of the acid species are captured in the first absorber and the balance is captured in the second absorber to below 10 ppm concentration in the outlet gas. The two absorbers operate at temperatures ranging from 20-70 degrees Celsius. The two absorbers and the main stripper of the alkaline solution operate at similar pressures ranging from 5-200 bara.

LED-Absorption-QEPAS Sensor for Biogas Plants

PubMed Central

Köhring, Michael; Böttger, Stefan; Willer, Ulrike; Schade, Wolfgang

2015-01-01

A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors; it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors. PMID:26007746

Evaluation of Gas-Cooled Pressurized Phosphoric Acid Fuel Cells for Electric Utility Power Generation

NASA Technical Reports Server (NTRS)

Faroque, M.

1983-01-01

Gas cooling is a more reliable, less expensive and a more simple alternative to conventional liquid cooling for heat removal from the phosphoric acid fuel cell (PAFC). The feasibility of gas-cooling was already demonstrated in atmospheric pressure stacks. Theoretical and experimental investigations of gas-cooling for pressurized PAFC are presented. Two approaches to gas cooling, Distributed Gas-Cooling (DIGAS) and Separated Gas-Cooling (SGC) were considered, and a theoretical comparison on the basis of cell performance indicated SGC to be superior to DIGAS. The feasibility of SGC was experimentally demonstrated by operating a 45-cell stack for 700 hours at pressure, and determining thermal response and the effect of other related parameters.

Near UV-Visible electronic absorption originating from charged amino acids in a monomeric protein† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc00880e

PubMed Central

Prasad, Saumya; Mandal, Imon; Singh, Shubham; Paul, Ashim; Mandal, Bhubaneswar

2017-01-01

Electronic absorption spectra of proteins are primarily characterized over the ultraviolet region (185–320 nm) of the electromagnetic spectrum. While recent studies on peptide aggregates have revealed absorption beyond 350 nm, monomeric proteins lacking aromatic amino acids, disulphide bonds, and active site prosthetic groups are expected to remain optically silent beyond 250 nm. Here, in a joint theoretical and experimental investigation, we report the distinctive UV-Vis absorption spectrum between 250 nm [ε = 7338 M–1 cm–1] and 800 nm [ε = 501 M–1 cm–1] in a synthetic 67 residue protein (α3C), in monomeric form, devoid of aromatic amino acids. Systematic control studies with high concentration non-aromatic amino acid solutions revealed significant absorption beyond 250 nm for charged amino acids which constitute over 50% of the sequence composition in α3C. Classical atomistic molecular dynamics (MD) simulations of α3C reveal dynamic interactions between multiple charged sidechains of Lys and Glu residues present in α3C. Time-dependent density functional theory calculations on charged amino acid residues sampled from the MD trajectories of α3C reveal that the distinctive absorption features of α3C may arise from two different types of charge transfer (CT) transitions involving spatially proximal Lys/Glu amino acids. Specifically, we show that the charged amino (NH3+)/carboxylate (COO–) groups of Lys/Glu sidechains act as electronic charge acceptors/donors for photoinduced electron transfer either from/to the polypeptide backbone or to each other. Further, the sensitivity of the CT spectra to close/far/intermediate range of encounters between sidechains of Lys/Glu owing to the three dimensional protein fold can create the long tail in the α3C absorption profile between 300 and 800 nm. Finally, we experimentally demonstrate the sensitivity of α3C absorption spectrum to temperature and pH-induced changes in protein structure. Taken together, our

Acid Gas Stability of Zeolitic Imidazolate Frameworks: Generalized Kinetic and Thermodynamic Characteristics

DOE PAGES

Bhattacharyya, Souryadeep; Han, Rebecca; Kim, Wun -Gwi; ...

2018-05-29

Here, acid gases such as SO 2 and CO 2 are present in many environments in which the use of nanoporous metal-organic frameworks (MOFs) is envisaged. Among metal-organic frameworks, zeolitic imidazolate frameworks (ZIFs) have been extensively explored as membranes or adsorbents. However, there is little systematic knowledge of the effects of acid gas exposure on the structure of ZIFs, in particular the mechanistic aspects of ZIF degradation by acid gases as well as the effects of ZIF crystal topology and linker composition on their stability. Here we present a generalized and quantitative investigation of the kinetic and thermodynamic acid gasmore » stability of a diverse range of ZIF materials. The stability of 16 ZIFs (of SOD, RHO, ANA, and GME topologies) under different environments – humid air, liquid water, and acid gases CO 2 and SO 2 (dry, humid, and aqueous) – are investigated by a suite of experimental and computational methods. The kinetics of ZIF degradation under exposure to humid SO 2 is studied in detail, and effective rate constants for acid gas degradation of ZIFs are reported for the first time. Remarkably, the kinetics of degradation of the diverse ZIFs correlate strongly with the linker pKa and ZIF water adsorption in a manner contrary to that expected from previous predictions in the literature. Furthermore, we find that the material ZIF-71 (RHO topology) shows much higher stability relative to the other ZIFs in humid SO 2 and CO 2 environments.« less

Acid Gas Stability of Zeolitic Imidazolate Frameworks: Generalized Kinetic and Thermodynamic Characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharyya, Souryadeep; Han, Rebecca; Kim, Wun -Gwi

Here, acid gases such as SO 2 and CO 2 are present in many environments in which the use of nanoporous metal-organic frameworks (MOFs) is envisaged. Among metal-organic frameworks, zeolitic imidazolate frameworks (ZIFs) have been extensively explored as membranes or adsorbents. However, there is little systematic knowledge of the effects of acid gas exposure on the structure of ZIFs, in particular the mechanistic aspects of ZIF degradation by acid gases as well as the effects of ZIF crystal topology and linker composition on their stability. Here we present a generalized and quantitative investigation of the kinetic and thermodynamic acid gasmore » stability of a diverse range of ZIF materials. The stability of 16 ZIFs (of SOD, RHO, ANA, and GME topologies) under different environments – humid air, liquid water, and acid gases CO 2 and SO 2 (dry, humid, and aqueous) – are investigated by a suite of experimental and computational methods. The kinetics of ZIF degradation under exposure to humid SO 2 is studied in detail, and effective rate constants for acid gas degradation of ZIFs are reported for the first time. Remarkably, the kinetics of degradation of the diverse ZIFs correlate strongly with the linker pKa and ZIF water adsorption in a manner contrary to that expected from previous predictions in the literature. Furthermore, we find that the material ZIF-71 (RHO topology) shows much higher stability relative to the other ZIFs in humid SO 2 and CO 2 environments.« less

Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Barry M.; McCaffrey, John G., E-mail: john.mccaffrey@nuim.ie

2016-01-28

Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y{sup 1}P←a{sup 1}S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅more » RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm{sup −1}). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr{sub 2} while this transition is quenched in Ba{sub 2}. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba{sub 2} indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications.« less

Thermal Boundary Layer Effects on Line-of-Sight Tunable Diode Laser Absorption Spectroscopy (TDLAS) Gas Concentration Measurements.

PubMed

Qu, Zhechao; Werhahn, Olav; Ebert, Volker

2018-06-01

The effects of thermal boundary layers on tunable diode laser absorption spectroscopy (TDLAS) measurement results must be quantified when using the line-of-sight (LOS) TDLAS under conditions with spatial temperature gradient. In this paper, a new methodology based on spectral simulation is presented quantifying the LOS TDLAS measurement deviation under conditions with thermal boundary layers. The effects of different temperature gradients and thermal boundary layer thickness on spectral collisional widths and gas concentration measurements are quantified. A CO 2 TDLAS spectrometer, which has two gas cells to generate the spatial temperature gradients, was employed to validate the simulation results. The measured deviations and LOS averaged collisional widths are in very good agreement with the simulated results for conditions with different temperature gradients. We demonstrate quantification of thermal boundary layers' thickness with proposed method by exploitation of the LOS averaged the collisional width of the path-integrated spectrum.

Laser Absorption spectrometer instrument for tomographic 2D-measurement of climate gas emission from soils

NASA Astrophysics Data System (ADS)

Seidel, Anne; Wagner, Steven; Dreizler, Andreas; Ebert, Volker

2014-05-01

One of the most intricate effects in climate modelling is the role of permafrost thawing during the global warming process. Soil that has formerly never totally lost its ice cover now emits climate gases due to melting processes[1]. For a better prediction of climate development and possible feedback mechanisms, insights into physical procedures (like e.g. gas emission from underground reservoirs) are required[2]. Therefore, a long-term quantification of greenhouse gas concentrations (and further on fluxes) is necessary and the related structures that are responsible for emission need to be identified. In particular the spatial heterogeneity of soils caused by soil internal structures (e.g. soil composition changes or surface cracks) or by surface modifications (e.g. by plant growth) generate considerable complexities and difficulties for local measurements, for example with soil chambers. For such situations, which often cannot be avoided, a spatially resolved 2D-measurement to identify and quantify the gas emission from the structured soil would be needed, to better understand the influence of the soil sub-structures on the emission behavior. Thus we designed a spatially scanning laser absorption spectrometer setup to determine a 2D-gas concentration map in the soil-air boundary layer. The setup is designed to cover the surfaces in the range of square meters in a horizontal plane above the soil to be investigated. Existing field instruments for gas concentration or flux measurements are based on point-wise measurements, so structure identification is very tedious or even impossible. For this reason, we have developed a tomographic in-situ instrument based on TDLAS ('tunable diode laser absorption spectroscopy') that delivers absolute gas concentration distributions of areas with 0.8m × 0.8m size, without any need for reference measurements with a calibration gas. It is a simple and robust device based on a combination of scanning mirrors and reflecting foils, so

New formulation of chemical peeling agent: 30% salicylic acid in polyethylene glycol. Absorption and distribution of 14C-salicylic acid in polyethylene glycol applied topically to skin of hairless mice.

PubMed

Ueda, Setsuko; Mitsugi, Koichi; Ichige, Kazumi; Yoshida, Kenji; Sakuma, Tomoko; Ninomiya, Shin-ichi; Sudou, Tetsuji

2002-04-01

Salicylic acid is used in chemical peeling procedures. However, they have caused many side effects, even salicylism. To achieve a salicylic acid peeling that would be safer for topical use, we recently developed a new formulation consisting of 30% salicylic acid in polyethylene glycol (PEG) vehicle. In an extension of our previous research, we studied the absorption of 30% salicylic acid labeled with 14C in PEG vehicle applied topically to the intact and damaged skin of male hairless mice. An ointment containing 3 mg salicylic acid in 10 mg vehicle was applied to both groups. In animals with intact skin, 1 h after application the plasma concentration of radioactivity was 1665.1 ng eq/ml, significantly lower than the 21437.6 ng eq/ml observed in mice with damaged skin. Microautoradiograms of intact skin showed that the level of radioactivity in the cornified cell layer was similar at 6 h after application. However, in damaged skin, the overall level of radioactivity showed a decrease by 3 h after application. In the carcasses remaining after the treated intact and damaged skin had been removed, 0.09 and 11.38% of the applied radioactivity remained, respectively. These findings confirm that 30% salicylic acid in PEG vehicle is little absorbed through the intact skin of hairless mice, and suggest that salicylism related to absorption through the skin of quantities of topically applied salicylic acid is not likely to occur in humans with intact skin during chemical peeling with this preparation. This new preparation of 30% salicylic acid in PEG vehicle is believed to be safe for application as a chemical peeling agent.

Bile acids: analysis in biological fluids and tissues

PubMed Central

Griffiths, William J.; Sjövall, Jan

2010-01-01

The formation of bile acids/bile alcohols is of major importance for the maintenance of cholesterol homeostasis. Besides their functions in lipid absorption, bile acids/bile alcohols are regulatory molecules for a number of metabolic processes. Their effects are structure-dependent, and numerous metabolic conversions result in a complex mixture of biologically active and inactive forms. Advanced methods are required to characterize and quantify individual bile acids in these mixtures. A combination of such analyses with analyses of the proteome will be required for a better understanding of mechanisms of action and nature of endogenous ligands. Mass spectrometry is the basic detection technique for effluents from chromatographic columns. Capillary liquid chromatography-mass spectrometry with electrospray ionization provides the highest sensitivity in metabolome analysis. Classical gas chromatography-mass spectrometry is less sensitive but offers extensive structure-dependent fragmentation increasing the specificity in analyses of isobaric isomers of unconjugated bile acids. Depending on the nature of the bile acid/bile alcohol mixture and the range of concentration of individuals, different sample preparation sequences, from simple extractions to group separations and derivatizations, are applicable. We review the methods currently available for the analysis of bile acids in biological fluids and tissues, with emphasis on the combination of liquid and gas phase chromatography with mass spectrometry. PMID:20008121

EVIDENCE FOR PHOTOIONIZATION-DRIVEN BROAD ABSORPTION LINE VARIABILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Tinggui; Yang, Chenwei; Wang, Huiyuan

2015-12-01

We present a qualitative analysis of the variability of quasar broad absorption lines using the large multi-epoch spectroscopic data set of the Sloan Digital Sky Survey Data Release 10. We confirm that variations of absorption lines are highly coordinated among different components of the same ion or the same absorption component of different ions for C iv, Si iv, and N v. Furthermore, we show that the equivalent widths (EWs) of the lines decrease or increase statistically when the continuum brightens or dims. This is further supported by the synchronized variations of emission and absorption-line EWs when the well-established intrinsicmore » Baldwin effect for emission lines is taken into account. We find that the emergence of an absorption component is usually accompanied by the dimming of the continuum while the disappearance of an absorption-line component is accompanied by the brightening of the continuum. This suggests that the emergence or disappearance of a C iv absorption component is only the extreme case, when the ionic column density is very sensitive to continuum variations or the continuum variability the amplitude is larger. These results support the idea that absorption-line variability is driven mainly by changes in the gas ionization in response to continuum variations, that the line-absorbing gas is highly ionized, and in some extreme cases, too highly ionized to be detected in UV absorption lines. Due to uncertainties in the spectroscopic flux calibration, we cannot quantify the fraction of quasars with asynchronized continuum and absorption-line variations.« less

The effects of 18β-glycyrrhetinic acid and glycyrrhizin on intestinal absorption of paeoniflorin using the everted rat gut sac model.

PubMed

He, Rui; Xu, Yongsong; Peng, Jingjing; Ma, Tingting; Li, Jing; Gong, Muxin

2017-01-01

Paeoniflorin (PF), the main active component of Shaoyao-Gancao-tang, possesses significantly antinociceptive effects and many other pharmacological activities. However, its poor intestinal absorption results in low bioavailability. Therefore, enhancing PF absorption plays a vital role in exerting its therapeutic effect. Shaoyao combined with Gancao exhibited a synergistic effect. The enhancement of PF absorption through the interaction of its constituents in intestinal absorption would be greatly implicated. The present study aimed at investigating the effects of glycyrrhizin, the main constituent of Gancao, and its main metabolite, 18β-glycyrrhetinic acid (18β-GA), on the intestinal absorptive behavior of PF, and the role of P-glycoprotein (P-gp) in PF absorption using the in vitro everted rat gut sac model. The results demonstrated that 1 mM of 18β-GA significantly increased PF absorption in both the jejunum and the ileum, while 100 μM of 18β-GA only promoted the ileum absorption and had no obvious effect on the jejunum absorption. The effect of glycyrrhizin on intestinal PF absorption was related to concentrations. One mM of glycyrrhizin significantly increased PF absorption in the jejunum after 45 min and in the ileum after 90 min. But 100 μM of glycyrrhizin had an inhibitory effect in the jejunum and no effect in the ileum before 60 min. Moreover, verapamil, the well-known P-gp inhibitor, could significantly enhance the PF absorption. In conclusion, the influence of 18β-GA and glycyrrhizin on the PF absorption was related to concentrations and intestinal segments. This might be involved in the intervention of efflux transport of PF mediated by intestinal P-gp.

BASIC STUDIES IN PERCUTANEOUS ABSORPTION.

DTIC Science & Technology

FATTY ACIDS, *SKIN(ANATOMY), ABSORPTION, ALKYL RADICALS, AMIDES, DIFFUSION, ELECTRON MICROSCOPY, HUMIDITY, LABORATORY ANIMALS, LIPIDS, ORGANIC SOLVENTS, PENETRATION, PRIVATION, PROTEINS, RATS, TEMPERATURE, WATER

Detection of martian amino acids by chemical derivatization coupled to gas chromatography: in situ and laboratory analysis.

PubMed

Rodier, C; Vandenabeele-Trambouze, O; Sternberg, R; Coscia, D; Coll, P; Szopa, C; Raulin, F; Vidal-Madjar, C; Cabane, M; Israel, G; Grenier-Loustalot, M F; Dobrijevic, M; Despois, D

2001-01-01

If there is, or ever was, life in our solar system beyond the Earth, Mars is the most likely place to search for. Future space missions will have then to take into account the detection of prebiotic molecules or molecules of biological significance such as amino acids. Techniques of analysis used for returned samples have to be very sensitive and avoid any chemical or biological contamination whereas in situ techniques have to be automated, fast and low energy consuming. Several possible methods could be used for in situ amino acid analyses on Mars, but gas chromatography would likely be the most suitable. Returned samples could be analyzed by any method in routine laboratory use such as gas chromatography, already successfully performed for analyses of organic matter including amino acids from martian meteorites. The derivatization step, which volatilizes amino acids to perform both in situ and laboratory analysis by gas chromatography, is discussed here. c2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Microwave absorptivity by sulfuric acid in the Venus atmosphere derived from the Venus Express Radio Science Experiment VeRa

NASA Astrophysics Data System (ADS)

Oschlisniok, J.; Pätzold, M.; Häusler, B.; Tellmann, S.; Bird, M.; Andert, T.; Remus, S.; Krüger, C.; Mattei, R.

2011-10-01

Earth's nearest planetary neighbour Venus is shrouded within a roughly 22 km thick three-layered cloud deck, which is located approximately 48 km above the surface and extends to an altitude of about 70 km. The clouds are mostly composed of sulfuric acid. The latter is responsible for a strong absorption of radio signals at microwaves, which is observed in radio occultation experiments. The absorption of the radio signal intensity is used to determine the abundance of H2SO4. This way a detailed study of the H2SO4 height distribution within the cloud deck is possible. The Venus Express spacecraft is orbiting Venus since 2006. The Radio Science Experiment VeRa onboard probes the atmosphere with radio signals at 3.4 cm (X-Band) and 13 cm (S-Band). Absorptivity profiles of the 3.4 cm radio wave and the resulting vertical sulfuric acid profiles in the cloud region of Venus' atmosphere are presented. The three-layered structure and a distinct latitudinal variation of H2SO4 are observed. Convective atmospheric motions within the equatorial latitudes, which transport absorbing material from lower to higher altitudes, are clearly visible. Results of the Venus Monitoring Camera (VMC) and the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) are compared with the VeRa results.

Development of a high-efficiency, gas-fired, absorption heat pump for residental and small-commercial applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, B.A.

1990-09-01

The purpose of the total project is to develop a gas-fired absorption heat pump for residential and small-commercial applications that will produce at least 1.6 Btu of heating and 0.7 Btu of cooling per Btu of heat content in the gas being burned. The primary technology advances that can be used to attain the new goals are higher efficiency cycles, increased flue efficiency, and better fluids. Flue efficiency technology is well developed, and fan-assisted combustion systems with condensing heat exchangers can limit flue and insulation losses to the 10% range. If this 10% loss assumption is made, the resulting targetmore » cycle COPs are 1.78 in heating mode and 0.78 in cooling mode at the ARI rating conditions. The objective of Phase 1 was to analyze working fluids and absorption-cycle concepts that are capable of performing at the target COPs and are potentially competitive with existing space-conditioning products in cost, operating life, and reliability. Six advanced cycles were evaluated with ammonia/water as the fluid pair. Then additional analysis was performed with other fluid pairs to determine whether cycle ranking would change depending on which fluid was used. It was concluded that the preferred cycle/fluid was the generator-absorber heat exchange (GAX) cycle using ammonia/water as the fluid pair. A cost estimate made by an independent manufacturing engineering firm for a residential heat pump based on the cycle/fluid combination determined that the GAX heat pump could be cost competitive with existing products. 20 refs., 28 figs., 2 tabs.« less

Significance of Ca-soap formation for calcium absorption in the rat.

PubMed Central

Gacs, G; Barltrop, D

1977-01-01

The significance of calcium soap formation in the inhibition of calcium absorption has been studied in rats. 47Ca labelled soaps of fatty acids were introduced into the duodenum and the absorption of calcium measured after four hours in a whole body counter. The absorption of calcium was inversely correlated with the chain length of the fatty acid varying from 1% for Ca-stearate to 60% for Ca-hexanoate. Increasing the degree of unsaturation of the fatty acid was accompanied by increased calcium absorption. The availability of calcium for absorption from the soaps was correlated with their solubility in 1% aqueous Na-tauroglycocholate. The percentages of calcium as soap in the small intestine and the faeces after intragastric administration of calcium and fats were similar, which suggests that the faecal content of calcium soaps is an index of intestinal soap formation. Soap formation was negligible when CaCl2 was given with tristearate, triolaeate, or tridecanoate and no depression of calcium absorption was observed. Calcium absorption was markedly impaired by the addition of phosphates at a Ca/P ratio of 1:1 irrespective of the presence of neutral fats. Stearic acid resulted in significant soap formation and reduced calcium absorption. The degree of Ca-soap formation and the inhibition of calcium absorption were well correlated. The results suggest that, although calcium soap formation may markedly depress calcium absorption in the rat, no significant soap formation takes place when fats are given in the form of triglycerides. PMID:838405

Carbon Dioxide Absorption Heat Pump

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor)

2002-01-01

A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO2 from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO2 gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

Kinetics of amino acid and glucose absorption following pancreatic diversion in the pig

NASA Technical Reports Server (NTRS)

Rerat, A.; Calmes, R.; Corring, T.; Vaissade, P.

1996-01-01

An experiment was conducted in the pig to determine the consequences of deprivation of exocrine pancreatic secretion on the composition and quantity of nutrients absorbed after intake of a balanced diet. Five growing pigs (53.8 kg body weight) were fitted with permanent catheters in the portal vein and the carotid artery and with an electromagnetic flow probe around the portal vein to measure the exchanges between the blood and the intestinal lumen. They were also fitted with a permanent catheter in the duct of Wirsung to educe the exocrine pancreatic secretion and another one in the duodenum in order to reintroduce it. In each animal, glucose, amino-N and amino acid absorption as well as insulin and glucagon production were measured over a period of 10 h after the meal (semi-purified diet based on purified starch and containing 180 g fish meal/kg, DM content of the meal 731 g), either in the presence of pancreatic juice (group C: immediate reintroduction), or in the absence of pancreatic juice (group D: deprivation). The deprivation of pancreatic juice provoked a marked depression in the absorption of glucose (D 67.9 (SEM 27.9) g/10 h, C 437.7 (SEM 39.5) g/10 h, P < 0.001), and of amino-N (D 7.55 (SEM 0.54) g/10 h, C 15.80 (SEM 0.79) g/10 h, P < 0.001). The composition of the mixture of amino acids in the portal blood was only slightly modified: only the levels of histidine (P < 0.05) and of valine (P < 0.06, NS) decreased in the absence of pancreatic juice. Insulin production was much lower (by 64%, P < 0.05) in the absence of pancreatic juice whereas that of glucagon was not affected.

Improved dissolution and absorption of ketoconazole in the presence of organic acids as pH-modifiers.

PubMed

Adachi, Masashi; Hinatsu, Yuta; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Nakatani, Manabu; Wada, Koichi; Yamamoto, Akira

2015-08-30

Formulation development of poorly water-soluble compounds can be challenging because of incomplete dissolution that causes low and variable bioavailability. Enhancing compound solubility is important and many techniques have been investigated to that end, but they require specific materials and machinery. This study investigates the incorporation of a pH-modifier as a method to increase compound solubility and uses ketoconazole (KZ), which is weakly basic (pKa: 6.5), as a model compound. Organic acids are effective pH-modifiers and are generally used in pharmaceutical industries. We successfully obtained granules containing variable organic acids (KZ/acid granule) using a high-shear mixer. Dissolution tests of the KZ/acid granule resulted in highly enhanced solubility under non-sink conditions. Adding water-soluble acids, such as citric acid (CA) and tartaric acid, resulted in more than 8-fold higher dissolution at pH 6.0 compared to that of KZ only. The granules containing citric acid (KZ/CA granule) improved the dissolution of KZ after oral administration to rats under low gastric acid conditions, where the bioavailability of the KZ/CA granules at elevated gastric pH was comparable with that of KZ only at gastric acidic pH. The incorporation of organic acids would result in effective therapeutic outcomes independent of gastric pH in patients. In addition, higher bioavailability of KZ was observed after oral administration of KZ/CA granules under gastric acidic pH conditions than that of KZ alone. Thus, CA improved the dissolution and absorption rate of KZ after oral administration. Copyright © 2015 Elsevier B.V. All rights reserved.

Response surface method for modeling the removal of carbon dioxide from a simulated gas using water absorption enhanced with a liquid-film-forming device.

PubMed

Nguyen, Diem-Mai Kim; Imai, Tsuyoshi; Dang, Thanh-Loc Thi; Kanno, Ariyo; Higuchi, Takaya; Yamamoto, Koichi; Sekine, Masahiko

2018-03-01

This paper presents the results from using a physical absorption process to absorb gaseous CO 2 mixed with N 2 using water by producing tiny bubbles via a liquid-film-forming device (LFFD) that improves the solubility of CO 2 in water. The influence of various parameters-pressure, initial CO 2 concentration, gas-to-liquid ratios, and temperature-on the CO 2 removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method (RSM) with a central composite design (CCD). Based on the analysis, a high efficiency of CO 2 capture can be reached in conditions such as low pressure, high CO 2 concentration at the inlet, low gas/liquid ratio, and low temperature. For instance, the highest removal efficiency in the RSM-CCD experimental matrix of nearly 80% occurred for run number 20, which was conducted at 0.30MPa, CO 2 concentration of 35%, gas/liquid ratio of 0.71, and temperature of 15°C. Furthermore, the coefficients of determination, R 2 , were 0.996 for the removal rate and 0.982 for the absorption rate, implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values. The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO 2 capture in air pollution treatment. Copyright © 2017. Published by Elsevier B.V.

Floquet theory of microwave absorption by an impurity in the two-dimensional electron gas

NASA Astrophysics Data System (ADS)

Chepelianskii, Alexei D.; Shepelyansky, Dima L.

2018-03-01

We investigate the dynamics of a two-dimensional electron gas (2DEG) under circular polarized microwave radiation in the presence of dilute localized impurities. Inspired by recent developments on Floquet topological insulators we obtain the Floquet wave functions of this system which allow us to predict the microwave absorption and charge density responses of the electron gas; we demonstrate how these properties can be understood from the underlying semiclassical dynamics even for impurities with a size of around a magnetic length. The charge density response takes the form of a rotating charge density vortex around the impurity that can lead to a significant renormalization of the external microwave field which becomes strongly inhomogeneous on the scale of a cyclotron radius around the impurity. We show that this inhomogeneity can suppress the circular polarization dependence which is theoretically expected for microwave induced resistance oscillations but which was not observed in experiments on semiconducting 2DEGs. Our explanation for this so far unexplained polarization independence has close similarities with the Azbel'-Kaner effect in metals where the interaction length between the microwave field and conduction electrons is much smaller than the cyclotron radius due to skin effect generating harmonics of the cyclotron resonance.

Laser engines operating by resonance absorption.

PubMed

Garbuny, M; Pechersky, M J

1976-05-01

The coherence properties and power levels of lasers available at present lend themselves to the remote operation of mechanical engines by resonance absorption in a working gas. Laser radiation is capable of producing extremely high temperatures in a gas. Limits to the achievable temperatures in the working gas of an engine are imposed by the solid walls and by loss of resonance absorption due to thermal saturation, bleaching, and dissociation. However, it is shown that by proper control of the laser beam in space, time, and frequency, as well as by choice of the absorbing gas, these limits are to a great extent removed so that very high temperatures are indeed attainable. The working gas is largely monatomic, preferably helium with the addition of a few volume percent of an absorber. Such a gas mixture, internally heated, permits an optimization of the expansion ratio, with resulting thermal efficiencies and work ratios, not achievable in conventional engines. A relationship between thermal efficiency and work ratio is derived that is quite general for the optimization condition. The performance of laser piston engines, turbines, and the Stirling cycle based on these principles is discussed and compared with conventional engine operation. Finally, a brief discussion is devoted to the possibility and concepts for the direct conversion of selective vibrational or electronic excitation into mechanical work, bypassing the translational degrees of freedom.

Are non-linearity effects of absorption important for MAX-DOAS observations?

NASA Astrophysics Data System (ADS)

Pukite, Janis; Wang, Yang; Wagner, Thomas

2017-04-01

For scattered light observations the absorption optical depth depends non-linearly on the trace gas concentrations if their absorption is strong. This is the case because the Beer-Lambert law is generally not applicable for scattered light measurements due to many (i.e. more than one) light paths contributing to the measurement. While in many cases a linear approximation can be made, for scenarios with strong absorption non-linear effects cannot always be neglected. This is especially the case for observation geometries with spatially extended and diffuse light paths, especially in satellite limb geometry but also for nadir measurements as well. Fortunately the effects of non-linear effects can be quantified by means of expanding the radiative transfer equation in a Taylor series with respect to the trace gas absorption coefficients. Herewith if necessary (1) the higher order absorption structures can be described as separate fit parameters in the DOAS fit and (2) the algorithm constraints of retrievals of VCDs and profiles can be improved by considering higher order sensitivity parameters. In this study we investigate the contribution of the higher order absorption structures for MAX-DOAS observation geometry for different atmospheric and ground properties (cloud and aerosol effects, trace gas amount, albedo) and geometry (different Sun and viewing angles).

Spatially Resolved HCN Absorption Features in the Circumnuclear Region of NGC 1052

NASA Astrophysics Data System (ADS)

Sawada-Satoh, Satoko; Roh, Duk-Gyoo; Oh, Se-Jin; Lee, Sang-Sung; Byun, Do-Young; Kameno, Seiji; Yeom, Jae-Hwan; Jung, Dong-Kyu; Kim, Hyo-Ryoung; Hwang, Ju-Yeon

2016-10-01

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s-1, redshifted by 149 and 212 km s-1 with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 1015-1016 cm-2, assuming an excitation temperature of 100-230 K. The absorption features show high optical depth localized on the receding jet side, where the free-free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.

Atmospheric photochemistry at a fatty acid-coated air-water interface

NASA Astrophysics Data System (ADS)

Rossignol, Stéphanie; Tinel, Liselotte; Bianco, Angelica; Passananti, Monica; Brigante, Marcello; Donaldson, D. James; George, Christian

2016-08-01

Although fatty acids are believed to be photochemically inert in the actinic region, complex volatile organic compounds are produced during illumination of an air-water interface coated solely with a monolayer of carboxylic acid. When aqueous solutions containing nonanoic acid (NA) at bulk concentrations that give rise to just over a monolayer of NA coverage are illuminated with actinic radiation, saturated and unsaturated aldehydes are seen in the gas phase, and more highly oxygenated products appear in the aqueous phase. This chemistry is probably initiated by triplet-state NA molecules excited by direct absorption of actinic light at the water surface. Because fatty acids-covered interfaces are ubiquitous in the environment, such photochemical processing will have a substantial impact on local ozone and particle formation.

[THE PHYSICAL CHEMICAL, BIOLOGICAL BASICS OF CELLS ABSORPTION OF UNESTERIFIED FATTY ACIDS; ALBUMIN, CAVEOLIN, CLATHRIN AND LIPID-BINDING PROTEINS OF CYTOPLASM (THE LECTURE)].

PubMed

Titov, V N; Shoibonov, B B

2016-03-01

From aposition of phylogenetic theory of general pathology, obesity and metabolic syndrome are pathology of fatty cells. However, the first is a pathology of phylogenetically early visceral fatty cells of omentum. They supply with substratum of energy realization of biologic function of trophology, homeostasis, endoecology and adaptation. The visceral fatty cells of omentum have no receptors to insulin and synthesize adaptively insulin and they are not characterized by biologic reaction of proliferation. The obesity is a pathology of late in phylogenesis subcutaneous adpocytes. They are insulin-dependent and supply with substratum of energy realization of one biologic function of locomotion--movement at the expense of constriction of cross-striated miocytes. The adipocytes in terms of adaptation synthesize humoral mediator adponectin and actively implement biologic function of proliferation. Under both aphysiologic conditions increases passive by gradient of concentration, absorption by cells albumin-unbound free fatty acids in unionized form in micellae's composition. The passive aphysiologic absorption of free fatty acids by cells which under intracellular compartmentalization don't oxidize mitochondria results in synthesis, accumulation of triglycerides in cytoplasm of cells which don't implement it physiologically. The aphysiologic absorption of free fatty acids by cells, their etherification in triglyceride, in particular, in phylogenetically late β-cells of islets and either late cardiomyocytes which fatty acids don't synthesize de novo results in development of aphysiologic processes and disorder of function. From position of biology, these cells in vivo are subjected to loss similar to apoptosis. The formation of corpuscles of apoptosis compromise biologic function of endoecology activating biologic reaction of inflammation.

What Drives the Outflows in Broad Absorption Line QSOs?

NASA Technical Reports Server (NTRS)

Begelman, Mitchell C.

1997-01-01

We have made progress in the areas related to the propulsion and confinement of gas responsible for broad absorption troughts in QSOs: Radiative Acceleration in BALQSOs; The "Ghost" of Lyman (alpha); and Magnetic Confinement of Absorbing Gas.

Hydrophobic amino acids as a new class of kinetic inhibitors for gas hydrate formation

PubMed Central

Sa, Jeong-Hoon; Kwak, Gye-Hoon; Lee, Bo Ram; Park, Da-Hye; Han, Kunwoo; Lee, Kun-Hong

2013-01-01

As the foundation of energy industry moves towards gas, flow assurance technology preventing pipelines from hydrate blockages becomes increasingly significant. However, the principle of hydrate inhibition is still poorly understood. Here, we examined natural hydrophobic amino acids as novel kinetic hydrate inhibitors (KHIs), and investigated hydrate inhibition phenomena by using them as a model system. Amino acids with lower hydrophobicity were found to be better KHIs to delay nucleation and retard growth, working by disrupting the water hydrogen bond network, while those with higher hydrophobicity strengthened the local water structure. It was found that perturbation of the water structure around KHIs plays a critical role in hydrate inhibition. This suggestion of a new class of KHIs will aid development of KHIs with enhanced biodegradability, and the present findings will accelerate the improved control of hydrate formation for natural gas exploitation and the utilization of hydrates as next-generation gas capture media. PMID:23938301

Recent Selected Ion Flow Tube (SIFT) Studies Concerning the Formation of Amino Acids in the Gas Phase

NASA Technical Reports Server (NTRS)

Jackson, Douglas M.; Adams, Nigel G.; Babcock, Lucia M.

2006-01-01

Recently the simplest amino acid, glycine, has been detected in interstellar clouds, ISC, although this has since been contested. In order to substantiate either of these claims, plausible routes to amino acids need to be investigated. For gas phase synthesis, the SIFT technique has been employed to study simple amino acids via ion-molecule reactions of several ions of interstellar interest with methylamine, ethylamine, formic acid, acetic acid, and methyl formate. Carboxylic acid type ions were considered in the reactions involving the amines. In reactions where the carboxylic acid and methyl formate neutrals were studied, the reactant ions were primarily amine ion fragments. It was observed that the amines and acids preferentially fragment or accept a proton whenever energetically possible. NH3(+), however, uniquely reacted with the neutrals via atom abstraction to form NH4(+). These studies yielded a body of data relevant to astrochemistry, supplementing the available literature. However, the search for gas phase routes to amino acids using conventional molecules has been frustrated. Our most recent research investigates the fragmentation patterns of several amino acids and several possible routes have been suggested for future study.

CO2 Absorption from Biogas by Glycerol: Conducted in Semi-Batch Bubble Column

NASA Astrophysics Data System (ADS)

puji lestari, Pratiwi; Mindaryani, Aswati; Wirawan, S. K.

2018-03-01

Biogas is a renewable energy source that has been developed recently. The main contents of Biogas itself are Methane and carbon dioxide (CO2) where Methane is the main component of biogas with CO2 as the highest impurities. The quality of biogas depends on the CO2 content, the lower CO2 levels, the higher biogas quality. Absorption is one of the methods to reduce CO2 level. The selections of absorbent and appropriate operating parameters are important factors in the CO2 absorption from biogas. This study aimed to find out the design parameters for CO2 absorption using glycerol that represented by the overall mass transfer coefficient (KLa) and Henry’s constant (H). This study was conducted in semi-batch bubble column. Mixed gas was contacted with glycerol in a bubble column. The concentration of CO2 in the feed gas inlet and outlet columns were analysed by Gas Chromatograph. The variables observed in this study were superficial gas velocity and temperatures. The results showed that higher superficial gas velocity and lower temperature increased the rate of absorption process and the amount of CO2 absorbed.

[Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

PubMed

Zheng, Hui-jie; Quan, Wei; Liu, Xiang; Chen, Yao; Lu, Ji-xi

2015-02-01

High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

Limiting Short-term Noise versus Optical Density in a Direct Absorption Spectrometer for Trace Gas Detection

NASA Astrophysics Data System (ADS)

Jervis, D.

2016-12-01

Field-deployable trace gas monitors are important for understanding a multitude of atmospheric processes: from forest photosynthesis and respiration [1], to fugitive methane emissions [2] and satellite measurement validation [3]. Consequently, a detailed knowledge of the performance limitations of these instruments is essential in order to establish reliable datasets. We present the short-term ( >1 Hz) performance of a long-pass direct absorption spectrometer as a function of the optical density of the absorption transition being probed. In particular, we identify fluctuations in the laser intensity as limiting the optical density uncertainty to 4x10-6/√Hz for weak transitions, and noise in the laser drive current as limiting the fractional noise in the optical density to 4x10-5/√Hz for deep transitions. We provide numerical and analytical predictions for both effects, as well as using the understanding of this phenomena to estimate how noise on neighboring strong and weak transitions couple to each other. All measurements were performed using the Aerodyne Research TILDAS Monitor, but are general to any instrument that uses direct absorption spectroscopy as a detection method. Wehr, R., et al. "Seasonality of temperate forest photosynthesis and daytime respiration." Nature 534.7609 (2016): 680-683. Conley, S., et al. "Methane emissions from the 2015 Aliso Canyon blowout in Los Angeles, CA." Science 351.6279 (2016): 1317-1320. Emmons, L. K., et al. "Validation of Measurements of Pollution in the Troposphere (MOPITT) CO retrievals with aircraft in situ profiles." Journal of Geophysical Research: Atmospheres 109.D3 (2004).

Haematological, blood gas and acid-base values in the Galgo Español (Spanish greyhound).

PubMed

Mesa-Sanchez, I; Zaldivar-Lopez, S; Couto, C G; Gamito-Gomez, A; Granados-Machuca, M M; Lopez-Villalba, I; Galan-Rodriguez, A

2012-07-01

Haematologic profiles, electrolyte concentrations, blood gas values and acid-base balance have been studied and reported in healthy greyhounds; however, there is only one study published on blood gas values in Galgos Españoles. Because of their purported common origins with greyhounds (same group and class), it was hypothesised that Galgos Españoles also have differences in haematologic values, electrolyte concentrations, blood gas values and acid-base balance compared to other non-sporting breeds. Venous blood samples from 30 Galgos Españoles and 20 dogs from different breeds were collected, and complete blood counts, electrolyte concentrations, blood gas values and acid-base balance were measured. From the 24 parameters analysed, 5 had statistically significant differences (P<0·05). Galgos Españoles had higher haematocrit (P<0·001), haemoglobin concentration (P=0·003), erythrocyte count (P=0·016) and pH (P=0·03), and lower platelet count (P=0·005), than those in other-breed dogs. These results confirm that significant haematologic differences exist in Galgos Españoles when compared with other dogs, although these differences are not as striking as in greyhounds. Practitioners need to be aware of these breed-specific differences in order to make accurate diagnoses in Galgos Españoles. © 2012 British Small Animal Veterinary Association.

Fatty Acid and Carbon Isotopic Evidence for type I Methanotrophs in Microbial Mats from a Shallow Marine Gas Seep, Coal Oil Point, CA.

NASA Astrophysics Data System (ADS)

Ding, H.; Valentine, D.

2005-12-01

To study the microbial community in a Southern California seep field, sediment and bacterial mat samples were collected from natural gas-bearing and gas-free surfaces at two distinct seeps in the Coal Oil Point seep field, offshore Santa Barbara. Fatty acids in these samples were extracted, analyzed and identified. Using gas chromatography (GC), more than 30 different fatty acids were separated. Generally, fatty acid concentrations in natural gas-bearing samples were about 5-fold higher compared to gas-free samples. Using gas chromatography mass sepctrometry (GC-MS), all separated fatty acids were identified in each sample. The major constituents included saturated 14:0, 16:0, 18:0, branched i-15, a-15 and unsaturated 16:1 and 18:1 series fatty acids. GC-IRMS (isotope ratio mass spectrometry) analysis provided the 13C of all major fatty acids and some 16:1 series fatty acids were found to be more depleted than -40% in samples associated with gas seepage. After treatment with dimethyl disufide (DMDS), the 16:1 series fatty acids were resolved into five distinct components, including common composition 16:1(7), bacterial specific i-16:1(7) and typical biomarkers of type I methnotrophs 16:1(8), 16(6) and 16:1(5), suggesting an important role for methnotrophs in seep sediments and microbial mats. These results provide evidence for the activity of type I methanotrophic bacteria in microbial mats and surficial sediments at the Coal Oil Point seep field, and have implications for methane cycling in this and other seep

Synthesis and characterization of porous silicon gas sensors

NASA Astrophysics Data System (ADS)

abbas, Roaa A.; Alwan, Alwan M.; Abdulhamied, Zainab T.

2018-05-01

In this work, photo-electrochemical etching process of n-type Silicon of resistivity(10 Ω.cm) and (100) orientation, using two illumination sources IR and violet wavelength in HF acid have been used to produce PSi gas detection device. The fabrication process was carried out at a fixed etching current density of 25mA/cm2 and at different etching time (5, 10, 15 and 20) min and (8, 16, 24, and 30) min. Two configurations of gas sensor configuration planer and sandwich have been made and investigated. The morphological properties have been studied using SEM,the FTIR measurement show that the (Si-Hx) and (Si-O-Si) absorption peak were increases with increasing etching time,and Photoluminescence properties of PSi layer show decrease in the peak of PL peak toward the violet shift. The gas detection process is made on the CO2 gas at different operating temperature and fixed gas concentration. In the planner structure, the gas sensing was measured through, the change in the resistance readout as a function to the exposure time, while for sandwich structure J-V characteristic have been made to determine the sensitivity.

Gas-particle partitioning of alcohol vapors on organic aerosols.

PubMed

Chan, Lap P; Lee, Alex K Y; Chan, Chak K

2010-01-01

Single particle levitation using an electrodynamic balance (EDB) has been found to give accurate and direct hygroscopic measurements (gas-particle partitioning of water) for a number of inorganic and organic aerosol systems. In this paper, we extend the use of an EDB to examine the gas-particle partitioning of volatile to semivolatile alcohols, including methanol, n-butanol, n-octanol, and n-decanol, on levitated oleic acid particles. The measured K(p) agreed with Pankow's absorptive partitioning model. At high n-butanol vapor concentrations (10(3) ppm), the uptake of n-butanol reduced the average molecular-weight of the oleic acid particle appreciably and hence increased the K(p) according to Pankow's equation. Moreover, the hygroscopicity of mixed oleic acid/n-butanol particles was higher than the predictions given by the UNIFAC model (molecular group contribution method) and the ZSR equation (additive rule), presumably due to molecular interactions between the chemical species in the mixed particles. Despite the high vapor concentrations used, these findings warrant further research on the partitioning of atmospheric organic vapors (K(p)) near sources and how collectively they affect the hygroscopic properties of organic aerosols.

Acidic sweep gas with carbonic anhydrase coated hollow fiber membranes synergistically accelerates CO2 removal from blood.

PubMed

Arazawa, D T; Kimmel, J D; Finn, M C; Federspiel, W J

2015-10-01

The use of extracorporeal carbon dioxide removal (ECCO2R) is well established as a therapy for patients suffering from acute respiratory failure. Development of next generation low blood flow (<500 mL/min) ECCO2R devices necessitates more efficient gas exchange devices. Since over 90% of blood CO2 is transported as bicarbonate (HCO3(-)), we previously reported development of a carbonic anhydrase (CA) immobilized bioactive hollow fiber membrane (HFM) which significantly accelerates CO2 removal from blood in model gas exchange devices by converting bicarbonate to CO2 directly at the HFM surface. This present study tested the hypothesis that dilute sulfur dioxide (SO2) in oxygen sweep gas could further increase CO2 removal by creating an acidic microenvironment within the diffusional boundary layer adjacent to the HFM surface, facilitating dehydration of bicarbonate to CO2. CA was covalently immobilized onto poly (methyl pentene) (PMP) HFMs through glutaraldehyde activated chitosan spacers, potted in model gas exchange devices (0.0151 m(2)) and tested for CO2 removal rate with oxygen (O2) sweep gas and a 2.2% SO2 in oxygen sweep gas mixture. Using pure O2 sweep gas, CA-PMP increased CO2 removal by 31% (258 mL/min/m(2)) compared to PMP (197 mL/min/m(2)) (P<0.05). Using 2.2% SO2 acidic sweep gas increased PMP CO2 removal by 17% (230 mL/min/m(2)) compared to pure oxygen sweep gas control (P<0.05); device outlet blood pH was 7.38 units. When employing both CA-PMP and 2.2% SO2 sweep gas, CO2 removal increased by 109% (411 mL/min/m(2)) (P<0.05); device outlet blood pH was 7.35 units. Dilute acidic sweep gas increases CO2 removal, and when used in combination with bioactive CA-HFMs has a synergistic effect to more than double CO2 removal while maintaining physiologic pH. Through these technologies the next generation of intravascular and paracorporeal respiratory assist devices can remove more CO2 with smaller blood contacting surface areas. A clinical need exists for more

Gas-Phase Amidation of Carboxylic Acids with Woodward’s Reagent K Ions

PubMed Central

Peng, Zhou; Pilo, Alice L.; Luongo, Carl A.; McLuckey, Scott A.

2015-01-01

Gas-phase amidation of carboxylic acids in multiply-charged peptides is demonstrated via ion/ion reactions with Woodward’s reagent K (wrk) in both positive and negative mode. Woodward’s reagent K, N-ethyl-3-phenylisoxazolium-3′-sulfonate, is a commonly used reagent that activates carboxylates to form amide bonds with amines in solution. Here, we demonstrate that the analogous gas-phase chemistry occurs upon reaction of the wrk ions and doubly protonated (or doubly deprotonated) peptide ions containing the carboxylic acid functionality. The reaction involves the formation of the enol ester intermediate in the electrostatic complex. Upon collisional activation, the ethyl amine on the reagent is transferred to the activated carbonyl carbon on the peptide, resulting in the formation of an ethyl amide (addition of 27 Da to the peptide) with loss of a neutral ketene derivative. Further collision-induced dissociation (CID) of the products and comparison with solution-phase amidation product confirms the structure of the ethyl amide. PMID:26122523

Influence of the gas-liquid flow configuration in the absorption column on photosynthetic biogas upgrading in algal-bacterial photobioreactors.

PubMed

Toledo-Cervantes, Alma; Madrid-Chirinos, Cindy; Cantera, Sara; Lebrero, Raquel; Muñoz, Raúl

2017-02-01

The potential of an algal-bacterial system consisting of a high rate algal pond (HRAP) interconnected to an absorption column (AC) via recirculation of the cultivation broth for the upgrading of biogas and digestate was investigated. The influence of the gas-liquid flow configuration in the AC on the photosynthetic biogas upgrading process was assessed. AC operation in a co-current configuration enabled to maintain a biomass productivity of 15gm -2 d -1 , while during counter-current operation biomass productivity decreased to 8.7±0.5gm -2 d -1 as a result of trace metal limitation. A bio-methane composition complying with most international regulatory limits for injection into natural gas grids was obtained regardless of the gas-liquid flow configuration. Furthermore, the influence of the recycling liquid to biogas flowrate (L/G) ratio on bio-methane quality was assessed under both operational configurations obtaining the best composition at an L/G ratio of 0.5 and co-current flow operation. Copyright © 2016 Elsevier Ltd. All rights reserved.

SPATIALLY RESOLVED HCN ABSORPTION FEATURES IN THE CIRCUMNUCLEAR REGION OF NGC 1052

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sawada-Satoh, Satoko; Roh, Duk-Gyoo; Oh, Se-Jin

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s{sup −1}, redshifted by 149 and 212 km s{sup −1} with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 10{sup 15}–10{sup 16} cm{sup −2}, assuming an excitation temperature ofmore » 100–230 K. The absorption features show high optical depth localized on the receding jet side, where the free–free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.« less

Nonequilibrium gas absorption in rotating permeable media

NASA Astrophysics Data System (ADS)

Baev, V. K.; Bazhaikin, A. N.

2016-08-01

The absorption of ammonia, sulfur dioxide, and carbon dioxide by water and aqueous solutions in rotating permeable media, a cellular porous disk, and a set of spaced-apart thin disks has been considered. The efficiency of cleaning air to remove these impurities is determined, and their anomalously high solubility (higher than equilibrium value) has been discovered. The results demonstrate the feasibility of designing cheap efficient rotor-type absorbers to clean gases of harmful impurities.

Percutaneous absorption of several chemicals, some pesticides included, in the red-winged blackbird

USGS Publications Warehouse

Rogers, J.G.; Cagan, R.H.; Kare, M.R.

1974-01-01

Percutaneous absorption in vivo through the skin of the feet of the red-winged blackbird (Agelaius phoeniceus) has been investigated. Absorption after 18-24 hours exposure to 0.01 M solutions of salicylic acid, caffeine, urea, 2,4-D, dieldrin, diethylstilbesterol, and DDT was measured. Of these, only DDT and diethylstilbesterol were not absorbed to a measurable degree. The solvents ethanol, dimethylsulfoxide (DMSO), and vegetable oil were compared with water in their effects on the absorption ofcaffeine, urea, and salicylic acid. Ethanol, DMSO,and oil each decreased percutaneous absorption of salicylic acid. DMSO increased absorption of caffeine, and ethanol had no effect on it. Neither DMSO nor ethanol affected penetration of urea. Partition coefficients (K) (epidermis/water) were determined for all seven penetrants. Compounds with higher values of K showed lower percutaneous absorption. These findings suggest that K may be useful to predict percutaneous absorption in vivo. It appears unlikely that percutaneous absorption contributes greatly to the body burden of 2,4-D and dieldrin in A. phoeniceus.

VARIATIONS BETWEEN DUST AND GAS IN THE DIFFUSE INTERSTELLAR MEDIUM. II. SEARCH FOR COLD GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reach, William T.; Heiles, Carl; Bernard, Jean-Philippe, E-mail: wreach@sofia.usra.edu

2017-01-01

The content of interstellar clouds, in particular the inventory of diffuse molecular gas, remains uncertain. We identified a sample of isolated clouds, approximately 100 M {sub ⊙} in size, and used the dust content to estimate the total amount of gas. In Paper I, the total inferred gas content was found significantly larger than that seen in 21 cm emission measurements of H i. In this paper we test the hypothesis that the apparent excess “dark” gas is cold H i, which would be evident in absorption but not in emission due to line saturation. The results show that theremore » is not enough 21 cm absorption toward the clouds to explain the total amount of “dark” gas.« less

Infrared gas phase study on plasma-polymer interactions in high-current diffuse dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Liu, Y.; Welzel, S.; Starostin, S. A.; van de Sanden, M. C. M.; Engeln, R.; de Vries, H. W.

2017-06-01

A roll-to-roll high-current diffuse dielectric barrier discharge at atmospheric pressure was operated in air and Ar/N2/O2 gas mixtures. The exhaust gas from the discharge was studied using a high-resolution Fourier-transform infrared spectrometer in the range from 3000 to 750 cm-1 to unravel the plasma-polymer interactions. The absorption features of HxNyOz, COx, and HCOOH (formic acid) were identified, and the relative densities were deduced by fitting the absorption bands of the detected molecules. Strong interactions between plasma and polymer (Polyethylene-2,6-naphthalate, or PEN) in precursor-free oxygen-containing gas mixtures were observed as evidenced by a high COx production. The presence of HCOOH in the gas effluent, formed through plasma-chemical synthesis of COx, turns out to be a sensitive indicator for etching. By adding tetraethylorthosilicate precursor in the plasma, dramatic changes in the COx production were measured, and two distinct deposition regimes were identified. At high precursor flows, a good agreement with the precursor combustion and the COx production was observed, whereas at low precursor flows an etching-deposition regime transpires, and the COx production is dominated by polymer etching.

2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. AIR FILTERS AND SWIPES ARE DISSOLVED WITH ACIDS AND THE REMAINING RESIDUES ARE SUSPENDED IN NITRIC ACID SOLUTION. THE SOLUTION IS PROCESSED THROUGH THE ATOMIC ABSORPTION SPECTROPHOTOMETER TO DETECT THE PRESENCE AND LEVELS OF BERYLLIUM. - Rocky Flats Plant, Health Physics Laboratory, On Central Avenue between Third & Fourth Streets, Golden, Jefferson County, CO

Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

USGS Publications Warehouse

Goerlitz, D.F.; Lamar, William L.

1967-01-01

A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2

Preparing ultrafine PbS powders from the scrap lead-acid battery by sulfurization and inert gas condensation

NASA Astrophysics Data System (ADS)

Xia, Huipeng; Zhan, Lu; Xie, Bing

2017-02-01

A novel method for preparing ultrafine PbS powders involving sulfurization combined with inert gas condensation is developed in this paper, which is applicable to recycle Pb from lead paste of spent lead-acid batteries. Initially, the effects of the evaporation and condensation temperature, the inert gas pressure, the condensation distance and substrate on the morphology of as-obtained PbS ultrafine particles are intensively investigated using sulfur powders and lead particles as reagents. Highly dispersed and homogeneous PbS nanoparticles can be prepared under the optimized conditions which are 1223 K heating temperature, 573 K condensation temperature, 100 Pa inert gas pressure and 60 cm condensation distance. Furthermore, this method is successfully applied to recycle Pb from the lead paste of spent lead acid battery to prepare PbS ultrafine powders. This work does not only provide the theoretical fundamental for PbS preparation, but also provides a novel and efficient method for recycling spent lead-acid battery with high added-value products.

Low-frequency radio absorption in Cassiopeia A

NASA Astrophysics Data System (ADS)

Arias, M.; Vink, J.; de Gasperin, F.; Salas, P.; Oonk, J. B. R.; van Weeren, R. J.; van Amesfoort, A. S.; Anderson, J.; Beck, R.; Bell, M. E.; Bentum, M. J.; Best, P.; Blaauw, R.; Breitling, F.; Broderick, J. W.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; de Geus, E.; Deller, A.; van Dijk, P. C. G.; Duscha, S.; Eislöffel, J.; Garrett, M. A.; Grießmeier, J. M.; Gunst, A. W.; van Haarlem, M. P.; Heald, G.; Hessels, J.; Hörandel, J.; Holties, H. A.; van der Horst, A. J.; Iacobelli, M.; Juette, E.; Krankowski, A.; van Leeuwen, J.; Mann, G.; McKay-Bukowski, D.; McKean, J. P.; Mulder, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pekal, R.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H. J. A.; Rothkaehl, H.; Schwarz, D. J.; Smirnov, O.; Soida, M.; Steinmetz, M.; Tagger, M.; Thoudam, S.; Toribio, M. C.; Vocks, C.; van der Wiel, M. H. D.; Wijers, R. A. M. J.; Wucknitz, O.; Zarka, P.; Zucca, P.

2018-05-01

Context. Cassiopeia A is one of the best-studied supernova remnants. Its bright radio and X-ray emission is due to shocked ejecta. Cas A is rather unique in that the unshocked ejecta can also be studied: through emission in the infrared, the radio-active decay of 44Ti, and the low-frequency free-free absorption caused by cold ionised gas, which is the topic of this paper. Aims: Free-free absorption processes are affected by the mass, geometry, temperature, and ionisation conditions in the absorbing gas. Observations at the lowest radio frequencies can constrain a combination of these properties. Methods: We used Low Frequency Array (LOFAR) Low Band Antenna observations at 30-77 MHz and Very Large Array (VLA) L-band observations at 1-2 GHz to fit for internal absorption as parametrised by the emission measure. We simultaneously fit multiple UV-matched images with a common resolution of 17″ (this corresponds to 0.25 pc for a source at the distance of Cas A). The ample frequency coverage allows us separate the relative contributions from the absorbing gas, the unabsorbed front of the shell, and the absorbed back of the shell to the emission spectrum. We explored the effects that a temperature lower than the 100-500 K proposed from infrared observations and a high degree of clumping can have on the derived physical properties of the unshocked material, such as its mass and density. We also compiled integrated radio flux density measurements, fit for the absorption processes that occur in the radio band, and considered their effect on the secular decline of the source. Results: We find a mass in the unshocked ejecta of M = 2.95 ± 0.48 M⊙ for an assumed gas temperatureof T = 100 K. This estimate is reduced for colder gas temperatures and, most significantly, if the ejecta are clumped. We measure the reverse shock to have a radius of 114″± 6″ and be centred at 23:23:26, +58:48:54 (J2000). We also find that a decrease in the amount of mass in the unshocked ejecta

H I absorption in nearby compact radio galaxies

NASA Astrophysics Data System (ADS)

Glowacki, M.; Allison, J. R.; Sadler, E. M.; Moss, V. A.; Curran, S. J.; Musaeva, A.; Deng, C.; Parry, R.; Sligo, M. C.

2017-05-01

H I absorption studies yield information on both active galactic nucleus (AGN) feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for H I absorption in a sample of 66 compact radio sources at 0.040 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak optical depths (3-87 per cent). Of the detections, 71 per cent exhibit asymmetric, broad (ΔvFWHM > 100 km s-1) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disc. Comparing mid-infrared colours of our galaxies with H I detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic discs. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of H I content within the host galaxy. This sample extends previous H I surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

Interaction of Gas Phase Oxalic Acid with Ammonia and its Atmospheric Implications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Xiu-Qiu; Liu, Yi-Rong; Huang, Teng

Oxalic acid is believed to play an important role in the formation and growth of atmospheric organic aerosols. However, as a common organic acid, the understanding of the larger clusters formed by gas phase oxalic acid with multiple ammonia molecules is incomplete. In this work, the structural characteristics and thermodynamics of oxalic acid clusters with up to six ammonia molecules have been investigated at the PW91PW91/6-311++G(3df,3pd) level of theory. We found that oxalic acid forms relatively stable clusters with ammonia molecules, and that ionization events play a key role. The analyses of the thermodynamics and atmospheric relevance indicate that themore » heterodimer (H2C2O4)(NH3) shows an obvious relative concentration in the atmosphere, and thus likely participates in new particle formation. However, with increasing number of ammonia molecules, the concentration of clusters decreases gradually. Additionally, clusters of oxalic acid with ammonia molecules are predicted to form favorably in low temperature conditions and show high Rayleigh scattering intensities.« less

Shock tube measurements of the optical absorption of triatomic carbon, C3

NASA Technical Reports Server (NTRS)

Jones, J. J.

1977-01-01

The spectral absorption of C3 has been measured in a shock tube using a test gas mixture of acetylene diluted with argon. The absorption of a pulsed xenon light source was measured by means of eight photomultiplier channels to a spectrograph and an accompanying drum camera. The postshock test gas temperature and pressure were varied over the range 3300-4300 K and 0.36 to 2.13 atmospheres, respectively. The results showed appreciable absorption from C3 for the wavelength range 300 to 540 nanometers. The computed electronic oscillator strength varied from 0.12 to 0.06 as a function of temperature.

The mid-IR Absorption Cross Sections of α- and β-NAT (HNO3 · 3H2O) in the range 170 to 185 K and of metastable NAD (HNO3 · 2H2O) in the range 172 to 182 K

NASA Astrophysics Data System (ADS)

Iannarelli, R.; Rossi, M. J.

2015-11-01

Growth and Fourier transform infrared (FTIR) absorption in transmission of the title nitric acid hydrates have been performed in a stirred flow reactor (SFR) under tight control of the H2O and HNO3 deposition conditions affording a closed mass balance of the binary mixture. The gas and condensed phases have been simultaneously monitored using residual gas mass spectrometry and FTIR absorption spectroscopy, respectively. Barrierless nucleation of the metastable phases of both α-NAT (nitric acid trihydrate) and NAD (nitric acid dihydrate) has been observed when HNO3 was admitted to the SFR in the presence of a macroscopic thin film of pure H2O ice of typically 1 µm thickness. The stable β-NAT phase was spontaneously formed from the precursor α-NAT phase through irreversible thermal rearrangement beginning at 185 K. This facile growth scheme of nitric acid hydrates requires the presence of H2O ice at thicknesses in excess of approximately hundred nanometers. Absolute absorption cross sections in the mid-IR spectral range (700-4000 cm-1) of all three title compounds have been obtained after spectral subtraction of excess pure ice at temperatures characteristic of the upper troposphere/lower stratosphere. Prominent IR absorption frequencies correspond to the antisymmetric nitrate stretch vibration (ν3(NO3-)) in the range 1300 to 1420 cm-1 and the bands of hydrated protons in the range 1670 to 1850 cm-1 in addition to the antisymmetric O-H stretch vibration of bound H2O in the range 3380 to 3430 cm-1 for NAT.

Relocation of blood gas laboratory to the emergency department helps decrease lactic acid values.

PubMed

Brazg, Jared; Huang, Phyllis; Weiner, Corey; Singh, Guneet; Likourezos, Antonios; Salem, Linda; Dickman, Eitan; Marshall, John

2018-03-20

Emergency physicians often rely on Lactic Acid (LA) values to make important clinical decisions. Accuracy of LA values improve when blood gas analysis is performed in the emergency department (ED) as opposed to a satellite laboratory (SL). To investigate an association between blood gas laboratory location and accuracy of ED lactic acid samples. The study team evaluated lactic acid values from venous and arterial blood gas samples drawn between June 1, 2015 and September 30, 2016. The study was exempt from institutional review board approval. Samples were separated into two groups: those which were drawn prior to and after relocation of the blood gas laboratory to the ED. The data, including patient demographic characteristics, acute illness severity indices, and blood gas results were compared within and between each group using t-test for continuous variables and chi-square test for categorical variables. The primary outcome was the mean lactate value measured in the SL group in 2015 compared to the ED group in 2016. Potassium and creatinine values were measured between the two groups as secondary outcomes. Of the 21,595 consecutive samples drawn, 10,363 samples were from the SL group and 11,232 from the ED group. The SL group included 5458 (52.7%) women; mean (SD) age was 61.8 (21.0). The ED group contained 5860 (52.2%) women; mean (SD) age was 61.7 (20.5). Mean Emergency Severity Index (ESI) were the same in each group at 2.31 and rates of Systemic Inflammatory Response Syndrome (SIRS) were also equivalent in each group at 22.2%. Significant differences were found between LA values in the SL group (mean 2.21mmol/L) and in the ED group (mean 1.99mmol/L) with a p value of <0.0001. There was a small statistical significance between the difference in potassium values in the SL group (mean 3.98meq/L) compared to the ED Group (mean 3.96meq/L) with a p value of 0.022. No significant difference was found between the creatinine values. These results suggest that mean

Relocation of blood gas laboratory to the emergency department helps decrease lactic acid values.

PubMed

Brazg, Jared; Huang, Phyllis; Weiner, Corey; Singh, Guneet; Likourezos, Antonios; Salem, Linda; Dickman, Eitan; Marshall, John

2018-03-12

Emergency Physicians often rely on Lactic Acid (LA) values to make important clinical decisions. Accuracy of LA values improve when blood gas analysis is performed in the emergency department (ED) as opposed to a satellite laboratory (SL). To investigate an association between blood gas laboratory location and accuracy of ED lactic acid samples. The study team evaluated lactic acid values from venous and arterial blood gas samples drawn between June 1, 2015 and September 30, 2016. The study was exempt from institutional review board approval. Samples were separated into two groups: those which were drawn prior to and after relocation of the blood gas laboratory to the ED. The data, including patient demographic characteristics, acute illness severity indices, and blood gas results were compared within and between each group using t-test for continuous variables and chi-square test for categorical variables. The primary outcome was the mean lactate value measured in the SL group in 2015 compared to the ED group in 2016. Potassium and creatinine values were measured between the two groups as secondary outcomes. Of the 21,595 consecutive samples drawn, 10,363 samples were from the SL group and 11,232 from the ED group. The SL group included 5458 (52.7%) women; mean (SD) age was 61.8 (21.0). The ED group contained 5860 (52.2%) women; mean (SD) age was 61.7 (20.5). Mean Emergency Severity Index (ESI) were the same in each group at 2.31 and rates of Systemic Inflammatory Response Syndrome (SIRS) were also equivalent in each group at 22.2%. Significant differences were found between LA values in the SL group (mean 2.21mmol/L) and in the ED group (mean 1.99mmol/L) with a p value of <0.0001. There was a small statistical significance between the difference in potassium values in the SL group (mean 3.98meq/L) compared to the ED Group (mean 3.96meq/L) with a p value of 0.022. No significant difference was found between the creatinine values. These results suggest that mean

Rumen morphometrics and the effect of digesta pH and volume on volatile fatty acid absorption.

PubMed

Melo, L Q; Costa, S F; Lopes, F; Guerreiro, M C; Armentano, L E; Pereira, M N

2013-04-01

The effects of rumen digesta volume and pH on VFA absorption and its relation to rumen wall morphology were evaluated. Nine rumen cannulated cows formed 3 groups based on desired variation in rumen morphology: The High group was formed by Holsteins yielding 25.9 kg milk/d and fed on a high-grain total mixed ration (TMR); the Medium group by Holstein-Zebu crossbreds yielding 12.3 kg milk/d and fed on corn silage, tropical pasture, and a commercial concentrate; and the Dry group by nonlactating grazing Jerseys fed exclusively on tropical pasture. Within each group, a sequence of 3 ruminal conditions was induced on each cow in 3 × 3 Latin Squares, with 7-d periods: high digesta volume and high pH (HVHP), low volume and high pH (LVHP), and low volume and low pH (LVLP). Rumen mucosa was biopsied on the first day of Period 1. Ruminal morphometric variables evaluated were mitotic index, absorptive surface and papillae number per square centimeter of wall, area per papillae, papillae area as a percentage of absorptive surface, and epithelium, keratinized layer, and nonkeratinized layer thickness. There was marked variation in rumen morphology among the groups of cows. Grazing Jerseys had decreased rumen wall absorptive surface area and basal cells mitotic index, and increased thickness of the epithelium and of the keratin layer compared with cows receiving concentrates. Mean rumen pH throughout the 4 h sampling period was: 6.78 for HVHP, 7.08 for LVHP, and 5.90 for LVLP (P < 0.01). The capacity of the rumen wall to absorb VFA was estimated by the Valerate/CrEDTA technique. The fractional exponential decay rate for the ratio of valeric acid to Cr (k Val/Cr) was determined by rumen digesta sampling at 20-min intervals during 4 h, after the mixing of markers and the return of the evacuated ruminal content. The k Val/Cr values for treatments HVHP, LVHP, and LVLP were, respectively: 19.6, 23.9, and 35.0 %/h (SEM = 2.01; P = 0.21 for contrast HVHP vs. LVHP and P < 0.01 for

Laser absorption spectroscopy - Method for monitoring complex trace gas mixtures

NASA Technical Reports Server (NTRS)

Green, B. D.; Steinfeld, J. I.

1976-01-01

A frequency stabilized CO2 laser was used for accurate determinations of the absorption coefficients of various gases in the wavelength region from 9 to 11 microns. The gases investigated were representative of the types of contaminants expected to build up in recycled atmospheres. These absorption coefficients were then used in determining the presence and amount of the gases in prepared mixtures. The effect of interferences on the minimum detectable concentration of the gases was measured. The accuracies of various methods of solution were also evaluated.

Effect of acute exposure to ergot alkaloids on short-chain fatty acid absorption and barrier function of isolated bovine ruminal epithelium

USDA-ARS?s Scientific Manuscript database

Ergot alkaloids present in endophyte-infected tall fescue are the causative agents for fescue toxicosis in cattle. Ergot alkaloids have been shown to cause a reduction in blood flow to the rumen epithelium as well as a decrease in short-chain fatty acid (SCFA) absorption from the washed rumen of ste...

OAS proteins and cGAS: unifying concepts in sensing and responding to cytosolic nucleic acids.

PubMed

Hornung, Veit; Hartmann, Rune; Ablasser, Andrea; Hopfner, Karl-Peter

2014-08-01

Recent discoveries in the field of innate immunity have highlighted the existence of a family of nucleic acid-sensing proteins that have similar structural and functional properties. These include the well-known oligoadenylate synthase (OAS) family proteins and the recently identified OAS homologue cyclic GMP-AMP (cGAMP) synthase (cGAS). The OAS proteins and cGAS are template-independent nucleotidyltransferases that, once activated by double-stranded nucleic acids in the cytosol, produce unique classes of 2'-5'-linked second messenger molecules, which - through distinct mechanisms - have crucial antiviral functions. 2'-5'-linked oligoadenylates limit viral propagation through the activation of the enzyme RNase L, which degrades host and viral RNA, and 2'-5'-linked cGAMP activates downstream signalling pathways to induce de novo antiviral gene expression. In this Progress article, we describe the striking functional and structural similarities between OAS proteins and cGAS, and highlight their roles in antiviral immunity.

Terahertz gas sensing based on time-domain-spectroscopy using a hollow-optical fiber gas cell

NASA Astrophysics Data System (ADS)

Suzuki, T.; Katagiri, T.; Matsuura, Y.

2018-02-01

Terahertz gas sensing system based on time-domain spectroscopy (THz-TDS) using a hollow-optical fiber gas cell is proposed. A hollow optical fiber functions as a long-path and low-volume gas cell and loading a dielectric layer on the inside of the fiber reduces the transmission loss and the dielectric layer also protects the metal layer of the fiber from deterioration. In the fabrication process, a polyethylene tube with a thin wall is drawn from a thick preform and a metal layer is formed on the outside of the tube. By using a 34-cm long fiber gas cell, NH3 gas with a concentration of 8.5 % is detected with a good SN ratio. However, the absorption peaks of NH3 and water vapor appeared at around 1.2 THz are not separated. To improve the frequency resolution in Fourier transformation, the time scan width that is decided by the scanning length of linear stage giving a time delay in the probing THz beam is enlarged. As a result, the absorption peaks at around 1.2 THz are successfully separated. In addition, by introducing a longer fiber gas cell of 60-cm length, the measurement sensitivity is improved and an absorption spectrum of NH3 gas with a concentration of 0.5 % is successfully detected.

In vitro percutaneous absorption studies and in vivo evaluation of anti-inflammatory activity of essential fatty acids (EFA) from fish oil extracts.

PubMed

Puglia, Carmelo; Tropea, Salvatore; Rizza, Luisa; Santagati, Natale Alfredo; Bonina, Francesco

2005-08-11

The aim of the present study was to evaluate the in vitro percutaneous absorption and the in vivo anti-inflammatory activity of EPA and DHA fatty acids from three oily extracts, obtained by acetonic extractions from the entrails of different varieties of Mediterranean fishes such as mackerel (Scomber scombrus), sardine (Sardina pilchardus) and horse mackerel (Trachurus mediterraneus). In the first part of our research, we focused our attention on the characterization of the oily extracts to determine their omega-3 polyunsaturated fatty acid content, then, we evaluated the in vitro percutaneous absorption through excised human skin (stratum corneum/epidermis membranes; SCE) of EPA and DHA contained in the extracts. In the second part, the fish oil which guaranteed the best in vitro permeation profile of these omega-3 fatty acids was studied in order to evaluate its inhibiting ability towards the in vivo UVB-induced skin erythema. From the results obtained, all the fish oils tested in this study presented significant amounts of omega-3 fatty acids EPA and DHA, and particularly sardine oil extract showed higher concentrations of these substances compared to the other two fish oils. The in vitro experiments revealed interesting fluxes of these compounds from sardine extract through the stratum corneum/epidermis membranes and an appreciable anti-inflammatory activity against UVB-induced erythema in human volunteers was also observed.

Distribution, synthesis, and absorption of kynurenic acid in plants.

PubMed

Turski, Michal P; Turska, Monika; Zgrajka, Wojciech; Bartnik, Magdalena; Kocki, Tomasz; Turski, Waldemar A

2011-05-01

Kynurenic acid (KYNA) is an endogenous antagonist of the ionotropic glutamate receptors and the α7 nicotinic acetylcholine receptor as well as an agonist of the G-protein-coupled receptor GPR35. In this study, KYNA distribution and synthesis in plants as well as its absorption was researched. KYNA level was determined by means of the high-performance liquid chromatography with fluorescence detection. KYNA was found in leaves, flowers, and roots of tested medicinal herbs: dandelion (Taraxacum officinale), common nettle (Urtica dioica), and greater celandine (Chelidoniummajus). The highest concentration of this compound was detected in leaves of dandelion--a mean value of 0.49 µg/g wet weight. It was shown that KYNA can be synthesized enzymatically in plants from its precursor, L-kynurenine, or absorbed by plants from the soil. Finally, the content of KYNA was investigated in 21 herbal tablets, herbal tea, herbs in sachets, and single herbs in bags. The highest content of KYNA in a maximum daily dose of herbal medicines appeared in St. John's wort--33.75 µg (tablets) or 32.60 µg (sachets). The pharmacological properties of KYNA and its presence in high concentrations in medicinal herbs may suggest that it possesses therapeutic potential, especially in the digestive system and should be considered a new valuable dietary supplement. © Georg Thieme Verlag KG Stuttgart · New York.

Effects of dietary sulfur concentration and forage-to-concentrate ratio on ruminal fermentation, sulfur metabolism, and short-chain fatty acid absorption in beef heifers.

PubMed

Amat, S; McKinnon, J J; Penner, G B; Hendrick, S

2014-02-01

This study evaluated the effects of dietary S concentration and forage-to-concentrate ratio (F:C) on ruminal fermentation, S metabolism, and short-chain fatty acid (SCFA) absorption in beef heifers. Sixteen ruminally cannulated heifers (initial BW 628 ± 48 kg) were used in a randomized complete block design with a 2 × 2 factorial treatment arrangement. The main factors included F:C (4% forage vs. 51% forage, DM basis) and the S concentration, which was modified using differing sources of wheat dried distillers grains with solubles (DDGS) to achieve low- and high-S diets (LS = 0.30% vs. HS = 0.67% S on a DM basis). Elemental S was also added to increase the S content for the HS diets. Serum sulfate concentration from blood, sulfide (S(2-)), and SCFA concentrations from ruminal fluid, hydrogen sulfide (H2S) concentration from the ruminal gas cap, and urinary sulfate concentration were determined. Continuous rumen pH and SCFA (acetate, butyrate, and propionate) absorption were measured. There were no interactions between S concentration and F:C. The F:C did not affect DMI (P = 0.26) or ruminal S metabolite concentrations (P ≥ 0.19), but ruminal pH was lower (P < 0.01) and SCFA absorption was greater (P < 0.01) for low F:C diets. Heifers fed HS diets had less DMI (P < 0.01) but greater ruminal pH (P < 0.01), greater concentrations of ruminal H2S (P < 0.01) and serum sulfate (P < 0.01), and greater urinary sulfate concentration (P < 0.01) and output (P < 0.01) relative to heifers fed LS diets. Ruminal H2S was positively correlated with serum sulfate (r = 0.89; P < 0.01). Ruminal acetate concentration was not affected (P = 0.26) by dietary S concentration. Heifers fed the HS diet had lower (P = 0.01) ruminal propionate concentration and tended to have lower (P = 0.06) butyrate concentration than heifers fed the LS diet. Ruminal acetate was greater (P = 0.01) and butyrate was less (P < 0.01) with the high F:C diet than the low F:C diet. Both HS (P = 0.06) and low F

European Regional Climate Zone Modeling of a Commercial Absorption Heat Pump Hot Water Heater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Vishaldeep; Shen, Bo; Keinath, Chris

2017-01-01

High efficiency gas-burning hot water heating takes advantage of a condensing heat exchanger to deliver improved combustion efficiency over a standard non-condensing configuration. The water heating is always lower than the gas heating value. In contrast, Gas Absorption Heat Pump (GAHP) hot water heating combines the efficiency of gas burning with the performance increase from a heat pump to offer significant gas energy savings. An ammonia-water system also has the advantage of zero Ozone Depletion Potential and low Global Warming Potential. In comparison with air source electric heat pumps, the absorption system can maintain higher coefficients of performance in coldermore » climates. In this work, a GAHP commercial water heating system was compared to a condensing gas storage system for a range of locations and climate zones across Europe. The thermodynamic performance map of a single effect ammonia-water absorption system was used in a building energy modeling software that could also incorporate the changing ambient air temperature and water mains temperature for a specific location, as well as a full-service restaurant water draw pattern.« less

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of antimony by automated-hydride atomic absorption spectrophotometry

USGS Publications Warehouse

Brown, G.E.; McLain, B.J.

1994-01-01

The analysis of natural-water samples for antimony by automated-hydride atomic absorption spectrophotometry is described. Samples are prepared for analysis by addition of potassium and hydrochloric acid followed by an autoclave digestion. After the digestion, potassium iodide and sodium borohydride are added automatically. Antimony hydride (stibine) gas is generated, then swept into a heated quartz cell for determination of antimony by atomic absorption spectrophotometry. Precision and accuracy data are presented. Results obtained on standard reference water samples agree with means established by interlaboratory studies. Spike recoveries for actual samples range from 90 to 114 percent. Replicate analyses of water samples of varying matrices give relative standard deviations from 3 to 10 percent.

In vitro assessment of potential intestinal absorption of some phenolic families and carboxylic acids from commercial instant coffee samples.

PubMed

López-Froilán, R; Ramírez-Moreno, E; Podio, N S; Pérez-Rodríguez, M L; Cámara, M; Baroni, M V; Wunderlin, D A; Sánchez-Mata, M C

2016-06-15

Coffee is one of the most consumed beverages in the world, being a source of bioactive compounds as well as flavors. Hydroxycinnamic acids, flavonols, and carboxylic acids have been studied in the samples of instant coffee commercialized in Spain. The studies about contents of food components should be complemented with either in vitro or in vivo bioaccessibility studies to know the amount of food components effectively available for functions in the human body. In this sense, a widely used in vitro model has been applied to assess the potential intestinal absorption of phenolic compounds and organic acids. The contents of hydroxycinnamic acids and flavonols were higher in instant regular coffee samples than in the decaffeinated ones. Bioaccessible phenolic compounds in most analyzed samples account for 20-25% of hydroxycinnamic acids and 17-26% of flavonols. This could mean that a great part of them can remain in the gut, acting as potential in situ antioxidants. Quinic, acetic, pyroglutamic, citric and fumaric acids were identified in commercial instant coffee samples. Succinic acid was found in the coffee blend containing chicory. All carboxylic acids showed a very high bioaccessibility. Particularly, acetic acid and quinic acid were found in higher contents in the samples treated with the in vitro simulation of gastrointestinal processes, compared to the original ones, which can be explained by their cleavage from chlorogenic acid during digestion. This is considered as a positive effect, since quinic acid is considered as an antioxidant inducer.

Are carboxyl groups the most acidic sites in amino acids? Gas-phase acidities, photoelectron spectra, and computations on tyrosine, p-hydroxybenzoic acid, and their conjugate bases.

PubMed

Tian, Zhixin; Wang, Xue-Bin; Wang, Lai-Sheng; Kass, Steven R

2009-01-28

Deprotonation of tyrosine in the gas phase was found to occur preferentially at the phenolic site, and the conjugate base consists of a 70:30 mixture of phenoxide and carboxylate anions at equilibrium. This result was established by developing a chemical probe for differentiating these two isomers, and the presence of both ions was confirmed by photoelectron spectroscopy. Equilibrium acidity measurements on tyrosine indicated that deltaG(acid)(o) = 332.5 +/- 1.5 kcal mol(-1) and deltaH(acid)(o) = 340.7 +/- 1.5 kcal mol(-1). Photoelectron spectra yielded adiabatic electron detachment energies of 2.70 +/- 0.05 and 3.55 +/- 0.10 eV for the phenoxide and carboxylate anions, respectively. The H/D exchange behavior of deprotonated tyrosine was examined using three different alcohols (CF3CH2OD, C6H5CH2OD, and CH3CH2OD), and incorporation of up to three deuterium atoms was observed. Two pathways are proposed to account for these results, and all of the experimental findings are supplemented with B3LYP/aug-cc-pVDZ and G3B3 calculations. In addition, it was found that electrospray ionization of tyrosine from a 3:1 (v/v) CH3OH/H2O solution using a commercial source produces a deprotonated [M-H]- anion with the gas-phase equilibrium composition rather than the structure of the ion that exists in aqueous media. Electrospray ionization from acetonitrile, however, leads largely to the liquid-phase (carboxylate) structure. A control molecule, p-hydroxybenzoic acid, was found to behave in a similar manner. Thus, the electrospray conditions that are employed for the analysis of a compound can alter the isomeric composition of the resulting anion.

Chemometric Approach to the Calibration of Light Emitting Diode Based Optical Gas Sensors Using High-Resolution Transmission Molecular Absorption Data.

PubMed

Mahbub, Parvez; Leis, John; Macka, Mirek

2018-05-15

Modeling the propagation of light from LED sources is problematic since the emission covers a broad range of wavelengths and thus cannot be considered as monochromatic. Furthermore, the lack of directivity of such sources is also problematic. Both attributes are characteristic of LEDs. Here we propose a HITRAN ( high-resolution transmission molecular absorption database) based chemometric approach that incorporates not-perfect-monochromaticity and spatial directivity of near-infrared (NIR) LED for absorbance calculations in 1-6% methane (CH 4 ) in air, considering CH 4 as a model absorbing gas. We employed the absorbance thus calculated using HITRAN to validate the experimentally measured absorbance of CH 4 . The maximum error between the measured and calculated absorbance values were within 1%. The approach can be generalized as a chemometric calibration technique for measuring gases and gas mixtures that absorb emissions from polychromatic or not-perfect-monochromatic sources, provided the gas concentration, optical path length, as well as blank and attenuated emission spectra of the light source are incorporated into the proposed chemometric approach.

A study of the cool gas in the Large Magellanic Cloud. I. Properties of the cool atomic phase - a third H i absorption survey

NASA Astrophysics Data System (ADS)

Marx-Zimmer, M.; Herbstmeier, U.; Dickey, J. M.; Zimmer, F.; Staveley-Smith, L.; Mebold, U.

2000-02-01

The cool atomic interstellar medium of the Large Magellanic Cloud (LMC) seems to be quite different from that in the Milky Way. In a series of three papers we study the properties of the cool atomic hydrogen in the LMC (Paper I), its relation to molecular clouds using SEST-CO-observations (Paper II) and the cooling mechanism of the atomic gas based on ISO-[\\CII]-investigations (Paper III). In this paper we present the results of a third 21 cm absorption line survey toward the LMC carried out with the Australia Telescope Compact Array (ATCA). 20 compact continuum sources, which are mainly in the direction of the supergiant shell LMC 4, toward the surroundings of 30 Doradus and toward the eastern steep \\HI\\ boundary, have been chosen from the 1.4 GHz snapshot continuum survey of Marx et al. We have identified 20 absorption features toward nine of the 20 sources. The properties of the cool \\HI\\ clouds are investigated and are compared for the different regions of the LMC taking the results of Dickey et al. (survey 2) into account. We find that the cool \\HI\\ gas in the LMC is either unusually abundant compared to the cool atomic phase of the Milky Way or the gas is clearly colder (\\Tc\\ ~ 30 K) than that in our Galaxy (\\Tc\\ ~ 60 K). The properties of atomic clouds toward 30 Doradus and LMC 4 suggest a higher cooling rate in these regions compared to other parts of the LMC, probably due to an enhanced pressure near the shock fronts of LMC 4 and 30 Doradus. The detected cool atomic gas toward the eastern steep \\HI\\ boundary might be the result of a high compression of gas at the leading edge. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

Properties of low-redshift QSO absorption systems - QSO-galaxy pairs

NASA Technical Reports Server (NTRS)

Womble, Donna S.

1993-01-01

The chance proximity of QSOs and galaxies provides unique opportunities to probe the extent and content of gas in the foreground galaxies through evaluation of the incidence and strength of absorption lines in the spectra of the background QSOs. Recent results on the observed properties of these low-redshift, heavy-element absorption systems are summarized. These results are discussed in the context of the galaxy morphologies and environments and are briefly compared with Galactic absorption and with the inferred properties of higher-redshift QSO absorption systems.

A flexible gas flow reaction cell for in situ x-ray absorption spectroscopy studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroner, Anna B., E-mail: anna.kroner@diamond.ac.uk; Gilbert, Martin; Duller, Graham

2016-07-27

A capillary-based sample environment with hot air blower and integrated gas system was developed at Diamond to conduct X-ray absorption spectroscopy (XAS) studies of materials under time-resolved, in situ conditions. The use of a hot air blower, operating in the temperature range of 298-1173 K, allows introduction of other techniques e.g. X-ray diffraction (XRD), Raman spectroscopy for combined techniques studies. The flexibility to use either quartz or Kapton capillaries allows users to perform XAS measurement at energies as low as 5600 eV. To demonstrate performance, time-resolved, in situ XAS results of Rh catalysts during the process of activation (Rh K-edge,more » Ce L{sub 3}-edge and Cr K-edge) and the study of mixed oxide membrane (La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3−δ}) under various partial oxygen pressure conditions are described.« less

Cold parsec-scale gas in a zabs ˜ 0.1 sub-damped Lyman α with disparate H2 and 21-cm absorption

NASA Astrophysics Data System (ADS)

Dutta, R.; Srianand, R.; Muzahid, S.; Gupta, N.; Momjian, E.; Charlton, J.

2015-04-01

We present a detailed analysis of a H2-bearing metal-rich sub-damped Lyman α system at zabs = 0.10115 towards the radio-loud quasar J0441-4313, at a projected separation of ˜7.6 kpc from a star-forming galaxy. The H2, {C I}} and {Na I} absorption are much stronger in the redder of the two components seen in the Hubble Space Telescope/Cosmic Origins Spectrograph spectrum. The best single-component fit to the strong H2 component gives log N(H2) = 16.61 ± 0.05. However, possible hidden saturation in the medium-resolution spectrum can allow for log N(H2) to be as high as 18.9. The rotational excitation temperature of H2 in this component is 133^{+33}_{-22} K. Photoionization models suggest 30-80 per cent of the total N(H I) is associated with the strong H2 component that has a density ≤100 cm-3 and is subject to a radiation field that is ≤0.5 times the Galactic mean field. The Very Long Baseline Array 1.4 GHz continuum image of the radio source contains only 27 per cent of the arcsecond scale emission. Using a previously published spectrum, no 21-cm absorption is found to be associated with the strong H2 component. This suggests that either the N(H I)) associated with this component is ≤50 per cent of the total N(H I)) or the gas covering factor is ≤0.27. This is consistent with the results of the photoionization model that uses ultraviolet radiation due to stars in the associated galaxy. The 21-cm absorption previously reported from the weaker H2 component suggests a spin temperature of ≤90 K, at odds with the weakness of H2, {C I} and {Na I} absorption in this component. From the inferred physical and chemical conditions, we suggest that the gas may be tracing a recent metal-rich outflow from the host galaxy.

Measurement of gas viscosity using photonic crystal fiber

NASA Astrophysics Data System (ADS)

Gao, R.-K.; Sheehe, S. L.; Kurtz, J.; O'Byrne, S.

2016-11-01

A new measurement technique for gas viscosity coefficient is designed and demonstrated using the technique of tunable diode laser absorption spectroscopy (TDLAS). Gas flow is driven by a pressure gradient between two gas cells, through a photonic crystal fiber (PCF) surrounded by a furnace for temperature adjustment. PCF with 20-micron diameter affords physical space for gas-light interaction and provides a basis for gas viscosity measurement by determining the time for flow to exit a capillary tube under the influence of a pressure gradient. Infrared radiation from a diode laser is coupled into the fiber to be guided through the gas, and the light attenuation due to absorption from the molecular absorbing species is measured by a photo detector placed at the exit of the fiber. A numerical model from Sharipov and Graur describing local number density distribution in a unsteady state is applied for the determination of gas viscosity, based on the number density of gas measured by the absorption of the laser light, using the Beer-Lambert law. The measurement system is confirmed by measuring the viscosity of CO2 as a reference gas.

Intestinal absorption of an arginine-containing peptide in cystinuria

PubMed Central

Asatoor, A. M.; Harrison, B. D. W.; Milne, M. D.; Prosser, D. I.

1972-01-01

Separate tolerance tests involving oral intake of the dipeptide, L-arginyl-L-aspartate, and of a corresponding free amino acid mixture, were carried out in a single type 2 cystinuric patient. Absorption of aspartate was within normal limits, whilst that of arginine was normal after the peptide but considerably reduced after the amino acid mixture. The results are compared with the increments of serum arginine found in eight normal subjects after the oral intake of the free amino acid mixture. Analyses of urinary pyrrolidine and of tetramethylenediamine in urine samples obtained after the two tolerance tests in the patient support the view that arginine absorption was subnormal after the amino acid mixture but within normal limits after the dipeptide. PMID:5045711

ELECTRIC POWER GENERATION USING A PHOSPHORIC ACID FUEL CELL ON A MUNICIPAL SOLID WASTE LANDFILL GAS STREAM

EPA Science Inventory

The report gives results of tests to verify the performance of a landfill gas pretreatment unit (GPU) and a phorsphoric acid fuel cell system. The complete system removes contaminants from landfill gas and produces electricity for on-site use or connection to an electric grid. Th...

Structured triacylglycerol containing behenic and oleic acids suppresses triacylglycerol absorption and prevents obesity in rats.

PubMed

Kojima, Makiko; Tachibana, Nobuhiko; Yamahira, Takashi; Seino, Satoshi; Izumisawa, Ayako; Sagi, Nobuo; Arishima, Toshiharu; Kohno, Mitsutaka; Takamatsu, Kiyoharu; Hirotsuka, Motohiko; Ikeda, Ikuo

2010-07-24

Dietary 1(3)-behenoyl-2,3(1)-dioleoyl-rac-glycerol (BOO) has been reported to inhibit pancreatic lipase activity in vitro and suppress postprandial hypertriacylglycerolemia in humans. In the present study, the anti-obesity activities of BOO and its inhibitory effects on lymphatic triacylglycerol (TAG) absorption were investigated in rats. In Experiment 1, rats were fed either BOO or soybean oil (SO) diet for 6 weeks. In the BOO diet, 20% of SO was replaced with an experimental oil rich in BOO. In Experiments 2 and 3, rats cannulated in the thoracic duct were administered an emulsions containing trioleoylglycerol (OOO) or an oil mixture (OOO:BOO, 9:1). Tri[1-14C]oleoylglycerol (14C-OOO) was added to the emulsions administered in Experiment 3. No observable differences were detected in food intake or body weight gain between the BOO and SO groups in Experiment 1. Plasma and liver TAG concentrations and visceral fat weights were significantly lower in the BOO group than in the SO group. The apparent absorption rate of fat was significantly lower in the BOO group than in the SO group. In Experiment 2, the lymphatic recovery of oleic and behenic acids was significantly lower at 5 and 6 h after BOO administration than after OOO administration. In Experiment 3, the lymphatic recovery of 14C-OOO was significantly lower at 5 and 6 h after BOO administration than after OOO administration. These results suggest that BOO prevents deposition of visceral fat and hepatic TAG by lowering and delaying intestinal absorption of TAG.

Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

DOE PAGES

Patel, Mogon; Bowditch, Martin; Jones, Ben; ...

2012-12-08

Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. In these studies, a Scout-EN TM heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time during storage at 75°C under vacuum conditions (< 1mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cmmore » -1, respectively. We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.« less

Acid monomer analysis in waterborne polymer systems by targeted labeling of carboxylic acid functionality, followed by pyrolysis - gas chromatography.

PubMed

Brooijmans, T; Okhuijsen, R; Oerlemans, I; Schoenmakers, P J; Peters, R

2018-05-14

Pyrolysis - gas chromatography - (PyGC) is a common method to analyse the composition of natural and synthetic resins. The analysis of acid functionality in, for example, waterborne polyacrylates and polyurethanes polymers has proven to be difficult due to solubility issues, inter- and intramolecular interaction effects, lack of detectability in chromatographic analysis, and lack of thermal stability. Conventional analytical techniques, such as PyGC, cannot be used for the direct detection and identification of acidic monomers, due to thermal rearrangements that take place during pyrolysis. To circumvent this, the carboxylic acid groups are protected prior to thermal treatment by reaction with 2-bromoacetophenone. Reaction conditions are investigated and optimised wrt. conversion measurements. The aproach is applied to waterborne polyacryalates and the results are discussed. This approach enables identification and (semi)quantitative analysis of different acid functionalities in waterborne polymers by PyGC. Copyright © 2018 Elsevier B.V. All rights reserved.

Surface Lewis acid-base properties of polymers measured by inverse gas chromatography.

PubMed

Shi, Baoli; Zhang, Qianru; Jia, Lina; Liu, Yang; Li, Bin

2007-05-18

Surface Lewis acid-base properties are significant for polymers materials. The acid constant, K(a) and base constant, K(b) of many polymers were characterized by some researchers with inverse gas chromatography (IGC) in recent years. In this paper, the surface acid-base constants, K(a) and K(b) of 20 kinds of polymers measured by IGC in recent years are summarized and discussed, including seven polymers characterized in this work. After plotting K(b) versus K(a), it is found that the polymers can be encircled by a triangle. They scatter in two regions of the triangle. Four polymers exist in region I. K(b)/K(a) of the polymers in region I are 1.4-2.1. The other polymers exist in region II. Most of the polymers are relative basic materials.

How gas cools (or, apples can fall up)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1987-01-01

This primer on gas cooling systems explains the basics of heat exchange within a refrigeration system, the principle of reverse-cycle refrigeration, and how a gas-engine-driven heat pump can provide cooling, additional winter heating capacity, and hot water year-round. Gas cooling equipment available or under development include natural gas chillers, engine-driven chillers, and absorption chillers. In cogeneration systems, heat recovered from an engine's exhaust and coolant may be used in an absorption chiller to provide air-conditioning. Gas desiccant cooling systems may be used in buildings and businesses that are sensitive to high humidity levels.

Nutritional value of protein hydrolysis products (oligopeptides and free amino acids) as a consequence of absorption and metabolism kinetics

NASA Technical Reports Server (NTRS)

Rerat, A.

1995-01-01

When pigs were submitted to duodenal infusion of solutions containing a large percentage of small peptides (PEP) or free amino acids with the same pattern (AAL) amino acids appear in the portal blood more rapidly and more uniformly after infusion of PEP then after infusion of AAL, with the notable exception of methionine for which the opposite was true. These differences were lowered when a carbohydrate (maltose dextrin) was present in the solution, but nevertheless remained significant for the first hour after the infusion. The long-term (8-hour) uptake of free amino acids into the liver and the peripheral tissues differed in profile according to the nature of the duodenal infusion. Peripheral uptake was appreciably less well balanced after infusion of free amino acids (deficiency of threonine and phenylalanine) than after infusion of small peptides (deficiency of methionine). Accordingly, in the rat, under conditions of discontinuous enteral nutrition the mixture of small peptides was of greater nutritive value than the mixture of free amino acids. It thus appears that the absorption kinetics which results in important variations in the temporal distribution of free amino acids in the tissues may be at the origin of transitory imbalances in tissue amino acid uptake, and as a result of a lower nutritive value.

Comparison of chemical-use between hydraulic fracturing, acidizing, and routine oil and gas development

DOE PAGES

Stringfellow, William T.; Camarillo, Mary Kay; Domen, Jeremy K.; ...

2017-04-19

The potential hazards and risks associated with well-stimulation in unconventional oil and gas development (hydraulic fracturing, acid fracturing, and matrix acidizing) have been investigated and evaluated and federal and state regulations requiring chemical disclosure for well-stimulation have been implemented as part of an overall risk management strategy for unconventional oil and gas development. Similar evaluations for chemicals used in other routine oil and gas development activities, such as maintenance acidizing, gravel packing, and well drilling, have not been previously conducted, in part due to a lack of reliable information concerning on-field chemical-use. In this study, we compare chemical-use between routinemore » activities and the more closely regulated well-stimulation activities using data collected by the South Coast Air Quality Monitoring District (SCAQMD), which mandates the reporting of both unconventional and routine on-field chemical-use for parts of Southern California. Analysis of this data shows that there is significant overlap in chemical-use between so-called unconventional activities and routine activities conducted for well maintenance, well-completion, or rework. A comparison within the SCAQMD shows a significant overlap between both types and amounts of chemicals used for well-stimulation treatments included under State mandatory-disclosure regulations and routine treatments that are not included under State regulations. A comparison between SCAQMD chemical-use for routine treatments and state-wide chemical-use for hydraulic fracturing also showed close similarity in chemical-use between activities covered under chemical disclosure requirements (e.g. hydraulic fracturing) and many other oil and gas field activities. The results of this study indicate regulations and risk assessments focused exclusively on chemicals used in well-stimulation activities may underestimate potential hazard or risk from overall oil field chemical-use.« less

Comparison of chemical-use between hydraulic fracturing, acidizing, and routine oil and gas development

PubMed Central

Camarillo, Mary Kay; Domen, Jeremy K.; Shonkoff, Seth B. C.

2017-01-01

The potential hazards and risks associated with well-stimulation in unconventional oil and gas development (hydraulic fracturing, acid fracturing, and matrix acidizing) have been investigated and evaluated and federal and state regulations requiring chemical disclosure for well-stimulation have been implemented as part of an overall risk management strategy for unconventional oil and gas development. Similar evaluations for chemicals used in other routine oil and gas development activities, such as maintenance acidizing, gravel packing, and well drilling, have not been previously conducted, in part due to a lack of reliable information concerning on-field chemical-use. In this study, we compare chemical-use between routine activities and the more closely regulated well-stimulation activities using data collected by the South Coast Air Quality Monitoring District (SCAQMD), which mandates the reporting of both unconventional and routine on-field chemical-use for parts of Southern California. Analysis of this data shows that there is significant overlap in chemical-use between so-called unconventional activities and routine activities conducted for well maintenance, well-completion, or rework. A comparison within the SCAQMD shows a significant overlap between both types and amounts of chemicals used for well-stimulation treatments included under State mandatory-disclosure regulations and routine treatments that are not included under State regulations. A comparison between SCAQMD chemical-use for routine treatments and state-wide chemical-use for hydraulic fracturing also showed close similarity in chemical-use between activities covered under chemical disclosure requirements (e.g. hydraulic fracturing) and many other oil and gas field activities. The results of this study indicate regulations and risk assessments focused exclusively on chemicals used in well-stimulation activities may underestimate potential hazard or risk from overall oil field chemical-use. PMID

Comparison of chemical-use between hydraulic fracturing, acidizing, and routine oil and gas development.

PubMed

Stringfellow, William T; Camarillo, Mary Kay; Domen, Jeremy K; Shonkoff, Seth B C

2017-01-01

The potential hazards and risks associated with well-stimulation in unconventional oil and gas development (hydraulic fracturing, acid fracturing, and matrix acidizing) have been investigated and evaluated and federal and state regulations requiring chemical disclosure for well-stimulation have been implemented as part of an overall risk management strategy for unconventional oil and gas development. Similar evaluations for chemicals used in other routine oil and gas development activities, such as maintenance acidizing, gravel packing, and well drilling, have not been previously conducted, in part due to a lack of reliable information concerning on-field chemical-use. In this study, we compare chemical-use between routine activities and the more closely regulated well-stimulation activities using data collected by the South Coast Air Quality Monitoring District (SCAQMD), which mandates the reporting of both unconventional and routine on-field chemical-use for parts of Southern California. Analysis of this data shows that there is significant overlap in chemical-use between so-called unconventional activities and routine activities conducted for well maintenance, well-completion, or rework. A comparison within the SCAQMD shows a significant overlap between both types and amounts of chemicals used for well-stimulation treatments included under State mandatory-disclosure regulations and routine treatments that are not included under State regulations. A comparison between SCAQMD chemical-use for routine treatments and state-wide chemical-use for hydraulic fracturing also showed close similarity in chemical-use between activities covered under chemical disclosure requirements (e.g. hydraulic fracturing) and many other oil and gas field activities. The results of this study indicate regulations and risk assessments focused exclusively on chemicals used in well-stimulation activities may underestimate potential hazard or risk from overall oil field chemical-use.

Comparison of chemical-use between hydraulic fracturing, acidizing, and routine oil and gas development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stringfellow, William T.; Camarillo, Mary Kay; Domen, Jeremy K.

The potential hazards and risks associated with well-stimulation in unconventional oil and gas development (hydraulic fracturing, acid fracturing, and matrix acidizing) have been investigated and evaluated and federal and state regulations requiring chemical disclosure for well-stimulation have been implemented as part of an overall risk management strategy for unconventional oil and gas development. Similar evaluations for chemicals used in other routine oil and gas development activities, such as maintenance acidizing, gravel packing, and well drilling, have not been previously conducted, in part due to a lack of reliable information concerning on-field chemical-use. In this study, we compare chemical-use between routinemore » activities and the more closely regulated well-stimulation activities using data collected by the South Coast Air Quality Monitoring District (SCAQMD), which mandates the reporting of both unconventional and routine on-field chemical-use for parts of Southern California. Analysis of this data shows that there is significant overlap in chemical-use between so-called unconventional activities and routine activities conducted for well maintenance, well-completion, or rework. A comparison within the SCAQMD shows a significant overlap between both types and amounts of chemicals used for well-stimulation treatments included under State mandatory-disclosure regulations and routine treatments that are not included under State regulations. A comparison between SCAQMD chemical-use for routine treatments and state-wide chemical-use for hydraulic fracturing also showed close similarity in chemical-use between activities covered under chemical disclosure requirements (e.g. hydraulic fracturing) and many other oil and gas field activities. The results of this study indicate regulations and risk assessments focused exclusively on chemicals used in well-stimulation activities may underestimate potential hazard or risk from overall oil field chemical-use.« less

DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Espada, D.; Matsushita, S.; Sakamoto, K.

2010-09-01

We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dishmore » observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas. Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.« less

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed through a Nonuniform Interstellar Medium

NASA Astrophysics Data System (ADS)

Huang, X.; Aldering, G.; Biederman, M.; Herger, B.

2017-11-01

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (≳ 10 {pc}) will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent widths, and of extinction, would be small. As a result, we conclude that nonuniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power-law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed Through Non-uniform Interstellar Medium

NASA Astrophysics Data System (ADS)

Huang, Xiaosheng; Aldering, Gregory; Biederman, Moriah; Herger, Brendan

2018-01-01

For Type Ia supernovae (SNe Ia) observed through a non-uniform interstellar medium (ISM) in its host galaxy, we investigate whether the non-uniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (>~ 10 pc) will translate to much smaller fluctuations on the scales of a SN photosphere. Therefore the typical amplitude of time variation due to non-uniform ISM, of absorption equivalent widths and of extinction, would be small. As a result, we conclude that non-uniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

Feasibility study of NaOH regeneration in acid gas removal unit using membrane electrolysis

NASA Astrophysics Data System (ADS)

Taufany, Fadlilatul; Pratama, Alvian; Romzuddin, Muhammad

2017-05-01

The world's energy demand is increasing with the development of human civilization. Due to limited energy resource, after 2020 fossil fuels thus is predicted will be replaced by renewable resources. Taking an example, one of the potential renewable energy to be considered is biogas, as its high content of methane, which can be produced via the fermentation process of the organic compounds under controlled anaerobic environment by utilizing the methanogen bacteria. However, prior the further use, this biogas must be purified from its impurities contents, i.e. acid gas of CO2 and H2S, up to 4% and 16 ppmv, respectively, in the acid gas removal unit. This such of purification efforts, will significantly increase the higher heating value of biogas, approximately from 600 to 900 Btu/Scf. During the purification process in this acid gas removal unit, NaOH solution is used as a liquid absorbent to reduce those acid gases content, in which the by-product of alkali salt (brine) was produced as waste. Here we report the feasibility study of the NaOH regeneration process in acid gas removal unit via membrane electrolysis technology, in which both the technical and economic aspects are taken account. To be precise in procedure, the anode semi-cell was filled with the brine solution, while the cathode semi-cell was filled with demineralized water, and those electrodes were separated by the cation exchange membrane. Furthermore, the applied potential was varied ranging from 5, 10, 15 and to 20 V, while the concentration of KCl electrolyte solutions were varied ranging from 0.01, 0.05, 0.1, and to 0.03 M. This study was conducted under controlled temperatures of 30 and 50 °C. Here we found that the % sodium recovery was increased along with the applied potential, temperature, and the decrease in KCl electrolyte concentration. We found that the best results, by means of the highest % sodium recovery, i.e. 97.26 %, was achieved under the experimental condition of temperature at 30

Rapid alternative absorption of dietary long-chain fatty acids with upregulation of intestinal glycosylated CD36 in liver cirrhosis.

PubMed

Yamamoto, Yasunori; Hiasa, Yoichi; Murakami, Hidehiro; Ikeda, Yoshio; Yamanishi, Hirofumi; Abe, Masanori; Matsuura, Bunzo; Onji, Morikazu

2012-07-01

Dietary long-chain fatty acid (LCFA) intake is an important risk factor for hepatic inflammation and hepatocarcinogenesis. An alternate route of dietary LCFA absorption has been suggested in patients with liver cirrhosis (LC). We aimed to determine this alternate route and to identify its mechanism. Twenty healthy control subjects and 47 patients with LC-n = 23 with portal hypertension [PH(+)LC] and 24 without portal hypertension [PH(-)LC)]-were enrolled. [¹³C]Palmitate (an LCFA) and octanoate (a medium-chain fatty acid [MCFA]) were administered by using gastrointestinal endoscopy. Breath ¹³CO₂ was measured to quantify metabolized fatty acids. We also examined intestinal specimens of patients in these groups. A more rapid increase in metabolized palmitate, which showed a pattern similar to that of octanoate metabolism, was observed in patients with LC than in healthy control subjects. The increase in the PH(-)LC group was higher than that in the PH(+)LC group. However, the concentration of metabolized palmitate increased with treatment of the PH(+)LC group with a portal-systemic shunt. Morphologic changes such as expanded lymph and blood vessels were present, and glycosylated CD36 increased in the jejunum of the PH(+)LC group. This group had high serum concentrations of glucagon-like peptide-2. These data suggest that dietary LCFAs, similar to MCFAs, are absorbed via blood vessels in patients with LC. Rapid absorption of LCFAs by an alternative method occurred in patients with LC. This altered LCFA processing is likely related to upregulation of intestinal glycosylated CD36 and could contribute to pathogenesis in patients with LC.

Gas-heat-pump development

NASA Astrophysics Data System (ADS)

Creswick, F. A.

Incentives for the development of gas heat pumps are discussed. Technical progress made on several promising technologies was reviewed. The status of development of gas-engine-driven heat pumps, the absorption cycle for the near- and long-term gas heat pump systems, the Stirling engine, the small Rankine-cycle engines, and gas-turbine-driven heat pump systems were briefly reviewed. Progress in the US, Japan, and Europe is noted.